Publications

Karmakar, NC, Yang, Y & Rahim, A 2018, Microwave Sleep Apnoea Monitoring, Springer, Germany.
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This book presents the design, development and field trials of radio frequency based wireless monitoring system for sleep apnoea patients. It contains 4 major areas including general background of wireless monitoring technology and MIMO in wireless body area network (WBAN), microwave hardware designs, virtual MIMO in WBAN and hardware system level implementation and field trials. At components level, this book presents the design theory, process and examples of bandpass filters, lowpass filters, low profile patch antennas, power amplifiers and oscillators which are the key elements in transducer designs in the body area network and cooperative communication wireless sensor network system. At system level, this book features the hardware integration, field trial and network coding techniques. This book also gives a presentation of virtual MIMO applications, e.g. MIMO implementation using FPGA, correlation coefficient measurement and correlation coefficient measurement. The book will create impact in the fields of wireless monitoring technology in biomedical engineering, which have been growing exponentially.

Abeywickrama, HV, Jayawickrama, BA, He, Y & Dutkiewicz, E 2018, 'Comprehensive energy consumption model for unmanned aerial vehicles, based on empirical studies of battery performance', IEEE Access, vol. 6, pp. 58383-58394.
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© 2018 IEEE. Unmanned aerial vehicles (UAVs) are fast gaining popularity in a wide variety of areas and are already being used for a range of tasks. Despite their many desirable features, a number of drawbacks hinder the potential of UAV applications. As typical UAVs are powered by on-board batteries, limited battery lifetime is identified as a key limitation in UAV applications. Thus, in order to preserve the available energy, planning UAV missions in an energy efficient manner is of utmost importance. For energy efficient UAV mission planning, it is necessary to predict the energy consumption of specific UAV manoeuvring actions. Accurate energy prediction requires a reliable and realistic energy consumption model. In this paper, we present a consistent and complete energy consumption model for UAVs based on empirical studies of battery usage for various UAV activities. We considered the impact of different flight scenarios and conditions on UAV energy consumption when developing the proposed model. The energy consumption model presented in this paper can be readily used for energy efficient UAV mission planning.

Abolhasan, M, Abdollahi, M, Ni, W, Jamalipour, A, Shariati, N & Lipman, J 2018, 'A Routing Framework for Offloading Traffic from Cellular Networks to SDN-based Multi-Hop Device-to-Device Networks', IEEE Transactions on Network and Service Management, vol. 15, no. 4, pp. 1516-1531.
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IEEE Device-to-Device (D2D) Communications are set to form an integral part of future 5G wireless networks. D2D communications have a number of benefits such as improving energy efficiency and spectrum utilization. Until now much of the D2D research in LTE and 5G-type network scenarios have focused on direct (one-hop) communications between two adjacent mobile devices. In this paper, we propose a new routing framework called Virtual Ad hoc Routing Protocol (VARP). This framework introduces significant advantages such as better security, lower routing overheads, and higher scalability, when compared to conventional ad hoc routing protocols. It also reduces traffic overhead in LTE networks using multi-hop D2D communications under management of a SDN-controller. Further, it enables the development of various types of routing protocols for different networking scenarios. To this end, a source-routing based protocol was developed on top of VARP, referred to as VARP-S. We present a detailed analytical study of routing overhead in the VARP-S protocol, as compared to overhead analysis of our previous proposed Hybrid SDN Architecture for wireless distributed networks (HSAW)IEEENetworkMehran. Our results show that VARP-S, compared to HSAW, achieves higher network scalability and lower power consumption for mobile nodes.

Alam, M, Jan, MA, Shu, L, He, X & Chen, Y 2018, 'Editorial: Current and Future Trends in Wireless Communications Protocols and Technologies', Mobile Networks and Applications, vol. 23, no. 3, pp. 377-381.
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Alam, M, Rayes, A, He, X, Atiquzzaman, M, Lloret, J & Tsang, KF 2018, 'Guest Editorial Introduction to the Special Issue on Dependable Wireless Vehicular Communications for Intelligent Transportation Systems (ITS)', IEEE Transactions on Intelligent Transportation Systems, vol. 19, no. 3, pp. 949-952.
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Aldebei, KW, He, X, Jia, W & Weichang Yeh 2018, 'SUDMAD: Sequential and unsupervised decomposition of a multi-author document based on a hidden markov model', Journal of the Association for Information Science and Technology, vol. 69, no. 2, pp. 201-214.
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Decomposing a document written by more than one author into sentences based on authorship is of great significance due to the increasing demand for plagiarism detection, forensic analysis, civil law (i.e., disputed copyright issues), and intelligence issues that involve disputed anonymous documents. Among existing studies for document decomposition, some were limited by specific languages, according to topics or restricted to a document of two authors, and their accuracies have big room for improvement. In this paper, we consider the contextual correlation hidden among sentences and propose an algorithm for Sequential and Unsupervised Decomposition of a Multi‐Author Document (SUDMAD) written in any language, disregarding topics, through the construction of a Hidden Markov Model (HMM) reflecting the authors' writing styles. To build and learn such a model, an unsupervised, statistical approach is first proposed to estimate the initial values of HMM parameters of a preliminary model, which does not require the availability of any information of author's or document's context other than how many authors contributed to writing the document. To further boost the performance of this approach, a boosted HMM learning procedure is proposed next, where the initial classification results are used to create labeled training data to learn a more accurate HMM. Moreover, the contextual relationship among sentences is further utilized to refine the classification results. Our proposed approach is empirically evaluated on three benchmark datasets that are widely used for authorship analysis of documents. Comparisons with recent state‐of‐the‐art approaches are also presented to demonstrate the significance of our new ideas and the superior performance of our approach.

Alzoubi, Y, Gill, AQ & Moulton, B 2018, 'A measurement model to analyze the effect of agile enterprise architecture on geographically distributed agile development', Journal of Software Engineering Research and Development, vol. 6, no. 4.
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Ara, P, Yu, K, Cheng, S, Dutkiewicz, E & Heimlich, MC 2018, 'Human Abdomen Path-Loss Modeling and Location Estimation of Wireless Capsule Endoscope Using Round-Trip Propagation Loss', IEEE Sensors Journal, vol. 18, no. 8, pp. 3266-3277.
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© 2001-2012 IEEE. A highly accurate location estimation of a capsule endoscope in the gastrointestinal tract in the range of several millimeters is a challenging task, as radio-frequency signals encounter high power loss and a highly dynamic channel propagation environment. Therefore, an accurate path-loss model is required for the development of accurate localization algorithms. This paper presents an in-body path-loss model for the human abdomen region at 2.4 GHz. To develop the path-loss model, electromagnetic simulations using the finite-difference time-domain method were carried out on three different anatomical human models from the Virtual Family. A mathematical expression for the path-loss model was proposed based on analysis of the measured loss at different capsule locations inside the small intestine. The proposed path-loss model is a good approximation to model in-body RF propagation, since real measurements are not completely practical for the capsule-endoscope subject. Based on the proposed path-loss model, the article also presents the 2-D location estimation of a capsule endoscope inside the small intestine using the trilateration method as well as the non-linear least squares algorithm. It is shown that with 90% probability, the location estimation error is less than 4 cm.

Arslanagic, S & Ziolkowski, RW 2018, 'Highly Subwavelength, Superdirective Cylindrical Nanoantenna (vol 120, 237401, 2018)', PHYSICAL REVIEW LETTERS, vol. 121, no. 24.
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Arslanagić, S & Ziolkowski, RW 2018, 'Highly Subwavelength, Superdirective Cylindrical Nanoantenna.', Physical review letters, vol. 120, no. 23, pp. 237401-237401.
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A superdirective cylindrical nanoantenna is demonstrated with a multilayered cylindrical metamaterial-inspired structure. Targeting specific scattering coefficients for the dipole and higher-order modes, the ideal limit of needle radiation is demonstrated. A five-layer system is optimized to demonstrate its approach to the theoretical directivity bound. While the resulting structure is scalable to any frequency regime, its highly subwavelength overall size (λ_{0}/10) takes advantage of combinations of positive and negative permittivity materials in the optical regime.

Babar, A, Bunker, D & Gill, AQ 2018, 'Investigating the Relationship between Business Analysts’ Competency and IS Requirements Elicitation: A Thematic-analysis Approach', Communications of the Association for Information Systems, vol. 42, no. 1, pp. 334-362.
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Bah, AO, Qin, P-Y, Ziolkowski, RW, Cheng, Q & Guo, YJ 2018, 'Realization of an Ultra-thin Metasurface to Facilitate Wide Bandwidth, Wide Angle Beam Scanning.', Scientific reports, vol. 8, no. 1.
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A wide bandwidth, ultra-thin, metasurface is reported that facilitates wide angle beam scanning. Each unit cell of the metasurface contains a multi-resonant, strongly-coupled unequal arm Jerusalem cross element. This element consists of two bent-arm, orthogonal, capacitively loaded strips. The wide bandwidth of the metasurface is achieved by taking advantage of the strong coupling within and between its multi-resonant elements. A prototype of the proposed metasurface has been fabricated and measured. The design concept has been validated by the measured results. The proposed metasurface is able to alleviate the well-known problem of impedance mismatch caused by mutual coupling when the main beam of an array is scanned. In order to validate the wideband and wide scanning ability of the proposed metasurface, it is integrated with a wideband antenna array as a wide angle impedance matching element. The metasurface-array combination facilitates wide angle scanning over a 6:1 impedance bandwidth without the need for bulky dielectrics or multi-layered structures.

Bargi, A, Xu, YD & Piccardi, M 2018, 'AdOn HDP-HMM: An Adaptive Online Model for Segmentation and Classification of Sequential Data', IEEE Transactions on Neural Networks and Learning Systems, pp. 3953-3968.
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Bowden, R & Veitch, D 2018, 'Finding the Right Tree: Topology Inference Despite Spatial Dependences', IEEE Transactions on Information Theory, vol. 64, no. 6, pp. 4594-4609.
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© 1963-2012 IEEE. Network tomographic techniques have almost exclusively been built on a strong assumption of mutual independence of link processes. We introduce model classes for link loss processes with non-Trivial spatial dependencies, for which the tree topology is nonetheless identifiable from leaf measurements using multicast probing. We show that these classes are large in a well-defined sense, and we provide an algorithm, SLTD, capable of returning the correct topology with certainty in the limit of infinite data.

Canning, J 2018, 'Water photonics, non-linearity, and anomalously large electro-optic coefficients in poled silica fibers', MRS COMMUNICATIONS, vol. 8, no. 1, pp. 29-34.
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Chen, SL, Qin, PY, Lin, W & Guo, YJ 2018, 'Pattern-Reconfigurable Antenna with Five Switchable Beams in Elevation Plane', IEEE Antennas and Wireless Propagation Letters, vol. 17, no. 3, pp. 454-457.
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© 2017 IEEE. Pattern-reconfigurable antennas with multiple switchable beams, especially with both boresight and endfire directions, are highly desired for wireless communications. In this letter, a novel pattern-reconfigurable antenna is proposed that provides an efficient solution. By reconfiguring parasitic striplines placed around a radiating dipole and reflecting metal pieces under the dipole using p-i-n diodes, the antenna main beam can be switched to five directions in the elevation plane, approximately from-90(left endfire),-45 , 0 (boresight),+45 to +90(right endfire). The proposed antenna operates at 2.45 GHz with dimensions of about 0.57λ× 0.45\lambda×, 0.28λ. An antenna prototype is fabricated and measured. For all five directional beams, the measured S-{11}| values are below 13 dB, and the measured realized gains range from 5.2 to 6.5 dBi. They agree reasonably well with the simulated ones.

Cheng, P, Chen, Z, Zhang, JA, Li, Y & Vucetic, B 2018, 'A Unified Precoding Scheme for Generalized Spatial Modulation', IEEE Transactions on Communications, vol. 66, no. 6, pp. 2502-2514.
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© 1972-2012 IEEE. Generalized spatial modulation (GSM) activates Nt (1 ≤ nt < Nt) available transmit antennas, and information is conveyed through nt modulated symbols as well as the index of the nt activated antennas. GSM strikes an attractive tradeoff between spectrum efficiency and energy efficiency. Linear precoding that exploits channel state information at the transmitter enhances the system error performance. For GSM with nt=1 (the traditional SM), the existing precoding methods suffer from high computational complexity. On the other hand, GSM precoding for nt ≥ 2 is not thoroughly investigated in the open literature. In this paper, we develop a unified precoding design for GSM systems, which universally works for all nt values. Based on the maximum minimum Euclidean distance criterion, we find that the precoding design can be formulated as a large-scale nonconvex quadratically constrained quadratic program problem. Then, we transform this challenging problem into a sequence of unconstrained subproblems by leveraging augmented Lagrangian and dual ascent techniques. These subproblems can be solved in an iterative manner efficiently. Numerical results show that the proposed method can substantially improve the system error performance relative to the GSM without precoding and features extremely fast convergence rate with a very low computational complexity.

Cui, Q, Gu, Y, Ni, W, Zhang, X, Tao, X, Zhang, P & Liu, RP 2018, 'Preserving Reliability of Heterogeneous Ultra-Dense Distributed Networks in Unlicensed Spectrum', IEEE Communications Magazine, vol. 56, no. 6, pp. 72-78.
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© 1979-2012 IEEE. This article investigates the prominent dilemma between capacity and reliability in heterogeneous ultra-dense distributed networks, and advocates a new measure of effective capacity to quantify the maximum sustainable data rate of a link while preserving the quality of service of the link in such networks. Recent breakthroughs are brought forth in developing the theory of the effective capacity in heterogeneous ultra-dense distributed networks. Potential applications of the effective capacity are demonstrated on the admission control, power control, and resource allocation of such networks, with substantial gains revealed over existing technologies. This new measure is of particular interest to ultra-dense deployment of the emerging 5G wireless networks in the unlicensed spectrum, leveraging the capacity gain brought by the use of the unlicensed band and the stringent reliability sustained by 5G in future heterogeneous network environments.

Dai, M, Cheng, S & He, XS 2018, 'Hybrid generative–discriminative hash tracking with spatio-temporal contextual cues', Neural Computing and Applications, vol. 29, no. 2, pp. 389-399.
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Visual object tracking is of a great application value in video monitoring systems. Recent work on video tracking has taken into account spatial relationship between the targeted object and its background. In this paper, the spatial relationship is combined with the temporal relationship between features on different video frames so that a real-time tracker is designed based on a hash algorithm with spatio-temporal cues. Different from most of the existing work on video tracking, which is regarded as a mechanism for image matching or image classification alone, we propose a hierarchical framework and conduct both matching and classification tasks to generate a coarse-to-fine tracking system. We develop a generative model under a modified particle filter with hash fingerprints for the coarse matching by the maximum a posteriori and a discriminative model for the fine classification by maximizing a confidence map based on a context model. The confidence map reveals the spatio-temporal dynamics of the target. Because hash fingerprint is merely a binary vector and the modified particle filter uses only a small number of particles, our tracker has a low computation cost. By conducting experiments on eight challenging video sequences from a public benchmark, we demonstrate that our tracker outperforms eight state-of-the-art trackers in terms of both accuracy and speed.

Ding, C, Sun, H-H, Ziolkowski, RW & Guo, YJ 2018, 'A Dual Layered Loop Array Antenna for Base Stations With Enhanced Cross-Polarization Discrimination', IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, vol. 66, no. 12, pp. 6975-6985.
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Dinh, H, Niyato, D, Nguyen, D, Dutkiewicz, E, Wang, P & Zhu, H 2018, 'A Dynamic Edge Caching Framework for Mobile 5G Networks', IEEE Wireless Communications, pp. 1-9.
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Mobile edge caching has emerged as a new paradigm to provide computing, networking resources, and storage for a variety of mobile applications. That helps achieve low latency, high reliability, and improve efficiency in handling a very large number of smart devices and emerging services (e.g., IoT, industry automation, virtual reality) in mobile 5G networks. Nonetheless, the development of mobile edge caching is challenged by the decentralized nature of edge nodes, their small coverage, limited computing, and storage resources. In this article, we first give an overview of mobile edge caching in 5G networks. After that, its key challenges and current approaches are discussed. We then propose a novel caching framework. Our framework allows an edge node to authorize the legitimate users and dynamically predicts and updates their content demands using the matrix factorization technique. Based on the prediction, the edge node can adopt advanced optimization methods to determine optimal content to store so as to maximize its revenue and minimize the average delay of its mobile users. Through numerical results, we demonstrate that our proposed framework provides not only an effective caching approach, but also an efficient economic solution for the mobile service provider.

Esmaili, N, Piccardi, M, Kruger, B & Girosi, F 2018, 'Analysis of healthcare service utilization after transport-related injuries by a mixture of hidden Markov models', PLoS ONE, vol. 13, no. 11, pp. 1-20.
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Fan, X, He, X, Xiang, C, Puthal, D, Gong, L, Nanda, P & Fang, G 2018, 'Towards System Implementation and Data Analysis for Crowdsensing BasedOutdoor RSS Maps', IEEE Access, vol. 6.
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With the explosive usage of smart mobile devices, sustainable access to wireless networks (e.g., WiFi) has become a pervasive demand. Most mobile users expect seamless network connection with low cost. Indeed, this can be achieved by using an accurate received signal strength (RSS) map of wireless access points. While existing methods are either costly or unscalable, the recently emerged mobile crowdsensing (MCS) paradigm is a promising technique for building RSS maps. MCS applications leverage pervasive mobile devices to collaboratively collect data. However, the heterogeneity of devices and the mobility of users could cause inherent noises and blank spots in collected dataset. In this paper, we study (1) how to tame the sensing noises from heterogenous mobile devices, and (2) how to construct accurate and complete RSS maps with random mobility of crowdsensing participants. First, we build a mobile crowdsensing system called iMap to collect RSS measurements with heterogeneous mobile devices. Second, through observing experimental results, we build statistical models of sensing noises and derive different parameters for each kind of mobile device. Third, we present the signal transmission model with measurement error model, and we propose a novel signal recovery scheme to construct accurate and complete RSS maps. The evaluation results show that the proposed method can achieve 90% and 95% recovery rate in geographic coordinate system and polar coordinate system, respectively.

Feng, X, Wan, W, Xu, RYD, Perry, S, Li, P & Zhu, S 2018, 'A novel spatial pooling method for 3D mesh quality assessment based on percentile weighting strategy', Computers & Graphics, vol. 74, pp. 12-22.
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Feng, X, Wan, W, Xu, RYD, Perry, S, Zhu, S & Liu, Z 2018, 'A new mesh visual quality metric using saliency weighting-based pooling strategy', Graphical Models, vol. 99, pp. 1-12.
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© 2018 Elsevier Inc. Several metrics have been proposed to assess the visual quality of 3D triangular meshes during the last decade. In this paper, we propose a mesh visual quality metric by integrating mesh saliency into mesh visual quality assessment. We use the Tensor-based Perceptual Distance Measure metric to estimate the local distortions for the mesh, and pool local distortions into a quality score using a saliency weighting-based pooling strategy. Three well-known mesh saliency detection methods are used to demonstrate the superiority and effectiveness of our metric. Experimental results show that our metric with any of three saliency maps performs better than state-of-the-art metrics on the LIRIS/EPFL general-purpose database. We generate a synthetic saliency map by assembling salient regions from individual saliency maps. Experimental results reveal that the synthetic saliency map achieves better performance than individual saliency maps, and the performance gain is closely correlated with the similarity between the individual saliency maps.

Feng, XIANG, Wan, W, Richard Yi Da Xu, Chen, H, Li, P & Sánchez, JA 2018, 'A perceptual quality metric for 3D triangle meshes based on spatial pooling', Frontiers of Computer Science, vol. 12, no. 4.
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Galvao, JR, Biffe Di Renzo, A, Esber Schaphauser, P, Dutra, G, Dreyer, UJ, Kalinowski, A, Canning, J, Zamarreno, CR, Cardozo Da Silva, JC & Martelli, C 2018, 'Optical fiber bragg grating instrumentation applied to horse gait detection', IEEE Sensors Journal, vol. 18, no. 14, pp. 5778-5785.
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© 2001-2012 IEEE. This paper presents two in vivo instrumentation techniques to study the different types of gait of horses performing athletics using fiber Bragg gratings (FBG). These techniques can be used as an auxiliary tool in the early diagnosis of injuries related to the horse's locomotor system, mainly in the distal portion of the digit, one of the most common causes of retirement when they are athletes. Therefore, the first technique presented consists of the fixation of FBGs without encapsulation, directly on the dorsal wall of the hoof in each of the limbs. In the second technique presented, the FBG sensor is encapsulated in a prototype developed using a composite material reinforced with carbon fiber in a horseshoe shape. The second technique is associated with digital image processing (DIP) for better visualization of the deformation and compression forces that act upon the limbs. The first method showed sensitivity to detection of the digit compression against the ground, being able to identify walking patterns. The second technique, with the encapsulated sensor elements, also allows the capture of characteristic signals of gait, such as step walk, trot, and gallop under training conditions. Both, FBG sensor interrogation and DIP, analysis techniques have proven good performance and promising results for the clinical and biomechanical study and medical evaluations of horses even during dynamic training and competitions.

Gao, X, Zhang, T, Du, J & Guo, YJ 2018, 'Design, modelling and simulation of a monolithic high-T c superconducting terahertz mixer', Superconductor Science and Technology, vol. 31, no. 11.
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© 2018 IOP Publishing Ltd. This paper presents a novel concept and design of a full monolithic integrated high-T c superconducting (HTS) Josephson junction terahertz (THz) harmonic mixer coupled with a circularly polarized (CP) antenna. The fully on-chip mixer device is very compact in size and utilizes the CP antenna to enhance the polarization orientation flexibility in coupling THz radiation. Electromagnetic simulations are carried out to optimize the coupling efficiency and axial ratio of the THz CP antenna, and the signal transmission and isolation characteristics of the monolithic circuit. An equivalent circuit model of the HTS THz mixer is then established and simulation is performed based on our previously measured step-edge Josephson junction characteristics to evaluate the device performance and validate the concept of design. The results show that a superior performance could be achieved from such a monolithic HTS mixer device, which is significantly better than any HTS THz harmonic mixers reported to date.

Gill, AQ, Henderson-Sellers, B & Niazi, M 2018, 'Scaling for agility: A reference model for hybrid traditional-agile software development methodologies', Information Systems Frontiers: a journal of research and innovation, vol. 20, no. 2, pp. 315-341.
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The adoption of agility at a large scale often requires the integration of agile and non-agile development elements for architecting a hybrid adaptive methodology. The challenge is ”which elements or components (agile or non-agile) are relevant to develop the context-aware hybrid adaptive methodology reference architecture?” This paper addresses this important challenge and develops a hybrid adaptive methodology reference architecture model using a qualitative constructive empirical research approach. In this way, we have uncovered the agility, abstraction, business value, business policy, rules, legal, context and facility elements or components that have not been explicitly modelled or discussed in International Standards (IS) such as the ISO/IEC 24744 metamodel. It is anticipated that a context-aware hybrid adaptive methodology can be architected by using the proposed context-aware hybrid adaptive methodology reference architecture elements for a particular situation when using a situational method engineering approach.

Guo, J, Yang, T, Yuan, J & Zhang, JA 2018, 'A novel linear physical-layer network coding scheme for Y-Channel without transmitter CSI', IEEE Transactions on Vehicular Technology, vol. 67, no. 10, pp. 10049-10053.
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© 1967-2012 IEEE. We propose a novel linear physical-layer network coding (NC) scheme for a fading Y-channel without channel state information at transmitters. In this three-user scheme, each user intends to realize a full data exchange with the other two users via a relay. Instead of directly decoding the users' messages from the received signal, the relay determines NC generator matrices and reconstructs linear NC codewords from its received signals to facilitate the information exchange. We present an explicit solution for NC generator matrices that minimize the NC error probability at high SNRs. We also present and prove an approximation of the NC error probability of the proposed scheme at high SNRs. Numerical results show that the proposed scheme outperforms existing ones, and its performance can be well characterized by the approximation.

Guo, J, Yuan, J & Zhang, J 2018, 'An Achievable Throughput Scaling Law of Wireless Device-to-Device Caching Networks with Distributed MIMO and Hierarchical Cooperations', IEEE Transactions on Wireless Communications, vol. 17, no. 1, pp. 492-505.
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© 2002-2012 IEEE. In this paper, we propose a new caching scheme for a random wireless device-to-device (D2D) network of n nodes with local caches, where each node intends to download files from a prefixed library via D2D links. Our proposed caching delivery includes two stages, employing distributed MIMO and hierarchical cooperations, respectively. The distributed MIMO is applied to the first stage between source nodes and neighbors of the destination node. The induced multiplexing gain and diversity gain increase the number of simultaneous transmissions, improving the throughput of the network. The hierarchical cooperations are applied to the second stage to facilitate the transmissions between the destination node and its neighbors. The two stages together exploit spatial degrees of freedom as well as spatial reuse. We develop an uncoded random caching placement strategy to serve this cooperative caching delivery. Analytical results show that the average aggregate throughput of the network scales almost linearly with n, with a vanishing outage probability. Furthermore, we derive an explicit expression of the optimal throughput as a function of system parameters, such as pathloss factor under a target outage probability. Analytical and numerical results demonstrate that our proposed scheme outperforms existing ones when the local cache size is limited.

Guo, P, Liu, M, Wu, J, Xue, Z & He, X 2018, 'Energy-Efficient Fault-Tolerant Scheduling Algorithm for Real-Time Tasks in Cloud-Based 5G Networks', IEEE Access, vol. 6, pp. 53671-53683.
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© 2013 IEEE. Green computing has become a hot issue for both academia and industry. The fifth-generation (5G) mobile networks put forward a high request for energy efficiency and low latency. The cloud radio access network provides efficient resource use, high performance, and high availability for 5G systems. However, hardware and software faults of cloud systems may lead to failure in providing real-time services. Developing fault tolerance technique can efficiently enhance the reliability and availability of real-time cloud services. The core idea of fault-tolerant scheduling algorithm is introducing redundancy to ensure that the tasks can be finished in the case of permanent or transient system failure. Nevertheless, the redundancy incurs extra overhead for cloud systems, which results in considerable energy consumption. In this paper, we focus on the problem of how to reduce the energy consumption when providing fault tolerance. We first propose a novel primary-backup-based fault-tolerant scheduling architecture for real-time tasks in the cloud environment. Based on the architecture, we present an energy-efficient fault-tolerant scheduling algorithm for real-time tasks (EFTR). EFTR adopts a proactive strategy to increase the system processing capacity and employs a rearrangement mechanism to improve the resource utilization. Simulation experiments are conducted on the CloudSim platform to evaluate the feasibility and effectiveness of EFTR. Compared with the existing fault-tolerant scheduling algorithms, EFTR shows excellent performance in energy conservation and task schedulability.

Guo, YJ, Xu, KD, Liu, Y & Tang, X 2018, 'Novel Surface Plasmon Polariton Waveguides with Enhanced Field Confinement for Microwave-Frequency Ultra-Wideband Bandpass Filters', IEEE ACCESS, vol. 6, pp. 10249-10256.
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Han, L, Liu, S, Han, S, Jia, W & Lei, J 2018, 'Owner based malware discrimination', Future Generation Computer Systems, vol. 80, pp. 496-504.
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© 2016 Elsevier B.V. A piece of malware code can be harmful in one's system but totally harmless in another's. In this paper, we point out that the detection of malicious code or software is actually a matter of discrimination which depends on the owners of the computer systems. We propose an owner based malicious software discrimination model, named as Unlimited Register Machine of Owners (URMO). First, we characterize and analyze the limitations of existing discrimination techniques in theory by using the discrimination model of Unlimited Register Machine (URM) and then move on to construct the URMO discrimination model by giving the two important elements of malicious behavior: an operation and the object of the operation. The relationship between an operation and the object of the operation is fundamental to solving the relativity of the discrimination problem about malice, which is also the advantage of the URMO model. Finally, by applying the model to discriminate real-world malware and comparing it with existing popular antivirus software, we demonstrate the effectiveness and superior performance of the URMO model.

He, Y, Jayawickrama, BA, Dutkiewicz, E, Srikanteswara, S & Mueck, M 2018, 'Priority Access and General Authorized Access Interference Mitigation in the Spectrum Access System', IEEE Transactions on Vehicular Technology, vol. 67, no. 6, pp. 4969-4983.
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© 1967-2012 IEEE. To meet the capacity needs of next generation wireless communications, the U.S. Federal Communications Commission has recently introduced the spectrum access system. Spectrum is shared between three tiers - incumbents, priority access licensees (PAL), and general authorized access (GAA) licensees. When the incumbents are absent, PAL and GAA share the spectrum under the constraint that GAA ensure the interference to PAL is no more than $-$40 dBm with at least 99% confidence. We consider the scenario where locations are not shared between PAL and GAA. We propose a PAL-GAA cochannel interference mitigation technique that does not expose base station locations. Our approach relies on GAA sharing the distribution and maximum number of transmitters in a finite area. We show how PAL can derive the distribution of the aggregate interference using the probability density function and characteristic function, and notify GAA about the exclusion zones in space that will guarantee that the interference requirement is met. We also propose a numerical approximation using inverse fast Fourier and discrete Fourier transforms. Analytically calculated distribution aligns well with the numerical results. Additionally, we formulate an optimization problem for the optimal exclusion zone size. We analytically prove convexity of the problem. Our approach reduces the exclusion zone size by over 42%, which gives significantly more spectral opportunities to GAA in the spatial domain.

Hou, ZJ, Yang, Y, Chiu, L, Zhu, X & Xue, Q 2018, 'Wideband Millimeter-Wave On-Chip Quadrature Coupler with Improved In-Band Flatness in 0.13-μm SiGe Technology', IEEE Electron Device Letters, vol. 39, no. 5, pp. 652-655.
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© 1980-2012 IEEE. This letter proposes a compact and broadband quadrature coupler with a center frequency of 55 GHz, which consists of a 90° broadside coupled-line to support the differential signal propagation and two T-type L-C networks to support the common signal propagation. To analyze the proposed coupler, an equivalent circuit model is provided for estimation of the distributed and lumped component values. The measured results of the proposed on-chip quadrature coupler show that the return loss and isolation are greater than 20 dB with a bandwidth of 105%, while the insertion loss is about -0.85 dB. The magnitude imbalances are less than 1 dB within the bandwidth of 56% and the phase differences are with ±1° errors within the bandwidth of 96.9%. The chip size, excluding the test pads, is only 0.31 × 0.22 mm2.

Hou, ZJ, Yang, Y, Chiu, L, Zhu, X, Dutkiewicz, E, Vardaxoglou, JC & Xue, Q 2018, 'A W-Band Balanced Power Amplifier Using Broadside Coupled Strip-Line Coupler in SiGe BiCMOS 0.13-&#x03BC;m Technology', IEEE Transactions on Circuits and Systems I: Regular Papers.
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IEEE Load-variation insensitivity, for impedance matching between power amplifiers (PAs) and transmitting antennas, contributes to challenging the design of millimeter-wave wireless systems. In this paper, a W-band two-way balanced PA based on a compact quadrature coupler with a broadside coupled strip-line (BCSL) as the core is presented to enhance the load-variation insensitivity and stability. The proposed coupler is truly broadband with low amplitude and phase imbalance. The proposed $W$-band balanced PA achieves higher power-added efficiency (PAE) and unsaturated output power Psat over wide frequency bandwidth. The W-band balanced PA is implemented in a 0.13- & #x03BC;m SiGe BiCMOS process and achieves a measured Psat of 16.3 dBm and a peak PAE of 14.1 & #x0025; at 100 GHz (with 1.6-V power supply). The measured Psat with 1-dB bandwidth is from 91 to 102 GHz. The measured results present the feasibility of the compact quadrature coupler. The total chip surface area (with pads) is 0.64 mm & #x00B2;, where the size of the proposed quadrature coupler area is only 0.04 mm & #x00B2;.

Hou, ZJ, Yang, Y, Zhu, X, Li, YC, Dutkiewicz, E & Xue, Q 2018, 'A Compact and Low-Loss Bandpass Filter Using Self-Coupled Folded-Line Resonator With Capacitive Feeding Technique', IEEE Electron Device Letters, vol. 39, no. 10.
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IEEE This letter proposes a compact and low-loss on-chip bandpass filter (BPF) design in (Bi)-CMOS technology. The proposed BPF consists of a self-coupled folded-line resonator (SCFLR) and a pair of metal-insulator-metal (MIM) capacitors. The proposed resonator has a property of flexible self-resonant-frequency (SRF) to form a transmission zero (TZ), which is analyzed in details by a simplified LC equivalent circuit. Moreover, the parametric studies of the feeding capacitance for the proposed BPF design have been performed to demonstrate the tenability of the resonant frequency. For verification, the proposed BPF is fabricated in a standard 0.13-μm (Bi)-CMOS technology. The measured results show that the proposed BPF has a notch with 25.4 dB suppression at 65 GHz and an insertion loss of 1.66 dB in the passband. The chip size of the device, excluding the test pads, is only 0.009mm2 (0.11 × 0.086mm2).

Hu, KZ, Tang, MC, Li, M & Ziolkowski, RW 2018, 'Compact, Low-Profile, Bandwidth-Enhanced Substrate Integrated Waveguide Filtenna', IEEE Antennas and Wireless Propagation Letters, vol. 17, no. 8, pp. 1552-1556.
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© 2011 IEEE. In this letter, a compact, low-profile, bandwidth-enhanced, dual-cavity substrate integrated waveguide (SIW) filtenna is demonstrated. Two SIW cavities are stacked vertically on top of each other. A complementary split-ring resonator slot is etched in the top surface of the uppermost cavity, causing the top surface to act as a patch antenna. The operational impedance bandwidth is significantly enhanced by merging the three resonances that arise from this configuration. One is introduced by the patch, and the other two are inherently generated by the two cavities. A metallized coupling post is introduced from the ground plane through both cavities to the upper surface to excite the fundamental resonant mode of the patch, as well as to electromagnetically couple the two cavities. The optimized filtenna was fabricated by a standard printed circuit board technology and tested. It has a low profile λ 0 and a compact size 0.62λ 0×0.62λ0 at its center frequency, f0=2.95GHz. The measured results agree well with their simulated values. They demonstrate a 6.3% fractional bandwidth, a maximum realized gain of 6.73 dBi, a flat gain profile within its passband, and an excellent out-of-band selectivity.

Ismaiel, B, Abolhasan, M, Ni, W, Smith, D, Franklin, D & Jamalipour, A 2018, 'Analysis of effective capacity and throughput of polling-based device-to-device networks', IEEE Transactions on Vehicular Technology, vol. 67, no. 9, pp. 8656-8666.
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© 1967-2012 IEEE. Next-generation wireless networks will give rise to heterogeneous networks by integrating multiple wireless access technologies to provide seamless mobility to mobile users with high-speed wireless connectivity. Device-to-device (D2D) communication has proven to be a promising technology that can increase the capacity and coverage of wireless networks. The D2D communication was first introduced in long-term evolution advanced (LTE-A) and has gained immense popularity for the offloading traffic using the licensed and unlicensed band. Challenges arise from resource allocation, provision of quality-of-service (QoS), and the quantification of capacity in an unlicensed band due to the distributed nature of Wi-Fi. In this paper, we propose an analytical performance model for the scalable MAC protocol (SC-MP) in which a resource allocation mechanism is based on the IEEE 802.11 point coordinated function to access the Wi-Fi channel for voice and video/multimedia traffic. In the SC-MP, D2D communication is applied to further offload the video/multimedia traffic. In particular, this paper establishes a three-state semi-Markovian model to derive a closed-form expression of effective capacity in terms of transmission rate and quality-of-service. Further, the SC-MP is analytically modeled using the four-state traditional Markov model to derive the saturation throughput. The analytical results are validated through simulations, hence, proving the appropriateness of the model.

Ismaiel, B, Abolhasan, M, Ni, W, Smith, D, Franklin, D, Dutkiewicz, E, Krunz, MM & Jamalipour, A 2018, 'PCF-based LTE Wi-Fi aggregation for coordinating and offloading the cellular traffic to D2D network', IEEE Transactions on Vehicular Technology, vol. 67, no. 12, pp. 12193-12203.
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© 2018 IEEE. Device-to-device (D2D) communication is a promising technology towards 5G networks. D2D communication can offload traffic using licensed/unlicensed band by establishing a direct communication between two users without traversing the base station or core network. However, one of the major challenges of D2D communication is resource allocation and guaranteeing quality-of-service (QoS). In this paper, we establish an optimal queuing scheduling and resource allocation problem for three-tier heterogeneous network based on LTE Wi-Fi aggregation, to offload voice/multimedia traffic from licensed band to unlicensed band using scalable MAC protocol (SC-MP) under various static delay constraints. The access mechanism used for Wi-Fi in SC-MP is point coordination function, which further offloads the multimedia traffic using D2D communication in unlicensed band. Resource allocation and optimal joint queuing scheduling problems are formulated with diverse QoS guarantee between licensed and unlicensed band to minimize the bandwidth of licensed band. Furthermore, an iterative algorithm is proposed to express the nonconvex problem as a series of subproblems based on block coordinate descent and difference of two convex functions (D.C) program. We have simulated the proposed scheme using two scenarios: Voice traffic using licensed band and voice traffic using both licensed and unlicensed band, whereas multimedia traffic uses unlicensed band for both the scenarios. The simulation results show that both the schemes perform better than the existing scheme and scenario 2 outperforms scenario 1.

Jan, MA, Nanda, He, XS & Liu, RP 2018, 'A Sybil Attack Detection Scheme for a Forest Wildfire Monitoring Application', Future Generation Computer Systems: the international journal of grid computing: theory, methods and applications, vol. 80, pp. 613-626.
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Wireless Sensor Networks (WSNs) have experienced phenomenal growth over the past decade. They are typically deployed in human-inaccessible terrains to monitor and collect time-critical and delay-sensitive events. There have been several studies on the use of WSN in different applications. All such studies have mainly focused on Quality of Service (QoS) parameters such as delay, loss, jitter, etc. of the sensed data. Security provisioning is also an important and challenging task lacking in all previous studies. In this paper, we propose a Sybil attack detection scheme for a cluster-based hierarchical network mainly deployed to monitor forest wildfire. We propose a two-tier detection scheme. Initially, Sybil nodes and their forged identities are detected by high-energy nodes. However, if one or more identities of a Sybil node sneak through the detection process, they are ultimately detected by the two base stations. After Sybil attack detection, an optimal percentage of cluster heads are elected and each one is informed using nomination packets. Each nomination packet contains the identity of an elected cluster head and an end user’s specific query for data collection within a cluster. These queries are user-centric, on-demand and adaptive to an end user requirement. The undetected identities of Sybil nodes reside in one or more clusters. Their goal is to transmit high false-negative alerts to an end user for diverting attention to those geographical regions which are less vulnerable to a wildfire. Our proposed approach has better network lifetime due to efficient sleep–awake scheduling, higher detection rate and low false-negative rate.

Jan, MA, Tan, Z, He, X & Ni, W 2018, 'Moving towards highly reliable and effective sensor networks', Ad-Hoc and Sensor Wireless Networks, vol. 40, no. 3-4, pp. 163-168.
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Wireless Sensor Networks (WSNs) have been the preferred choice for the design and deployment of next generation monitoring and control systems [1]. In these networks, the sensor nodes forward their sensed data towards a centralized base station. The neighboring nodes frequently sense correlated data and forward towards the base station, using disjoints multiple paths [2]. As a result, the area around the base station becomes congested with all the traffic converging towards it. Apart from packet lost due to congestion, a significant number of packets are lost due to interference, packet collision, node failure and transmission errors [3]. For a successful monitoring of the deployed environment, the critical data collected by the sensor nodes need to be reliably and effectively delivered to the base station. Given the error-prone nature of the wireless links, ensuring reliable transmission of data from resource-constrained sensor nodes towards the base station continues to be one of the major challenges in the field of WSNs [4]. Retransmission and redundancy are classified as the two main approaches to achieve data transmission reliability in WSNs. However, retransmission and redundancy techniques perform better when using hop-by-hop transmission approach as compared to end-to-end transmission. Using hop-by-hop approach introduces in-node processing overhead and incurs high overall latency in reporting data to the base station. As a result, hybrid approaches need to be adopted to ensure highly reliable and effective data transmission towards the base stations in WSNs. The specific objective of this special issue is to collect high quality research articles with solid background in both theoretical and practical aspects of reliability and effectiveness for WSNs. This special issue focuses on various topics pertaining to reliable and effective communication such as, fault-tolerance, energy-efficiency, topology control, load-balancing, propagation pathloss, co-channe...

Jayawickrama, BA, He, Y, Dutkiewicz, E & Mueck, MD 2018, 'Scalable Spectrum Access System for Massive Machine Type Communication', IEEE NETWORK, vol. 32, no. 3, pp. 154-160.
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Ji, LY, Qin, PY & Guo, YJ 2018, 'Wideband Fabry-Perot Cavity Antenna with a Shaped Ground Plane', IEEE Access, vol. 6, pp. 2291-2297.
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© 2013 IEEE. This paper proposes a novel approach to broaden the 3-dB gain bandwidth of Fabry-Perot cavity (FPC) antennas by utilizing a shaped ground plane. The shaped ground plane is flat in the middle to accommodate the source antenna, and then angled up in the shape of trapezoids. Compared with an FPC antenna with a traditional flat ground plane, the 3-dB gain bandwidth of the one with a shaped ground plane is improved from 11% to 20.2% with the maximum realized gain and the 10-dB impedance bandwidth almost unchanged. To validate the feasibility of the proposed approach, an FPC antenna prototype has been designed, fabricated, and measured. It consists of a U-slot rectangular microstrip patch antenna as the source, a Rogers RT6006 superstrate as the partially reflective surface, and the proposed shaped ground plane. Measured results on input reflection coefficients and radiation patterns agree well with simulated ones. Therefore, this new approach can be an effective way to enhance the gain bandwidth without increasing the cavity profile or using multi-layer superstrate structures.

Ju, M, Ding, C, Zhang, D & Guo, YJ 2018, 'Gamma-correction-based visibility restoration for single hazy images', IEEE Signal Processing Letters, vol. 25, no. 7, pp. 1084-1088.
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© 1994-2012 IEEE. In this letter, a concise gamma-correction-based dehazing model (GDM) is proposed. This GDM explicitly describes the inner relationship between the gamma correction (GC) and the traditional scattering model. Combined with the existing priori constraints, GDM is further approximated into a one-dimensional (1-D) function to seek the only unknown constant that is used for haze removal. Using the determined constant, the scene albedo can be recovered, eliminating the haze from single hazy images. The proposed GDM is able to suppress the halo/blocking artifacts in the recovered results due to the scene albedo, which is less sensitive to the determined constant. Simulation results on different types of benchmark images verify that the proposed technique outperforms state-of-the-art methods in terms of both recovery, quality, and real-time performance.

Karmokar, DK, Guo, YJ, Qin, PY, Chen, SL & Bird, TS 2018, 'Substrate integrated waveguide-based periodic backward-to-forward scanning leaky-wave antenna with low cross-polarization', IEEE Transactions on Antennas and Propagation, vol. 66, no. 8, pp. 3846-3856.
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© 1963-2012 IEEE. For many leaky-wave antennas (LWAs), it is challenging to realize beam scanning through broadside. A problem is the presence of an open stopband (OSB), which restricts radiation in the broadside direction. In this paper, a novel substrate integrated waveguide (SIW)-based LWA is described to overcome the OSB problem and provide beam scanning continuously from the backward to the forward direction from a conventional periodic LWA. It is demonstrated that the n =-1 spatial harmonic can be excited efficiently from an SIW LWA and enables broadside radiation. However, it was found in our initial design that when the beam scans through the broadside, the cross-polarization level increases significantly compared to the beam close to the backfire direction. A technique is developed to reduce the cross-polarization level. As a result, a new antenna configuration is created. The antenna design has been realized and measured to validate the concept. The measured beam scanning range of the prototype is from -74° to +45° (119° of beam scanning) when the frequency sweeps from 7.625 to 11 GHz, and the measured cross-polarization level is 20.8 dB low at the main beam direction for the broadside beam.

Khan, AA, Abolhasan, M & Ni, W 2018, 'An evolutionary game theoretic approach for stable and optimized clustering in vanets', IEEE Transactions on Vehicular Technology, vol. 67, no. 5, pp. 4501-4513.
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© 1967-2012 IEEE. Discovering and maintaining efficient routes for data dissemination in vehicular ad hoc networks (VANETs) has proven to be a very challenging problem. Clustering is one of the control protocols used to provide efficient and stable routes for data dissemination. However, the rapid changes in network topology in VANETs creates frequent cluster reformation, which can seriously affect route stability. We propose a novel evolutionary game theoretic (EGT) framework to automate the clustering of nodes and nominations of cluster heads, to achieve cluster stability in VANETs. The equilibrium point is proven analytically and the stability is also tested using Lyapunov function. The performance of the proposed evolutionary game is empirically investigated with different cost functions using static and mobile scenarios. The simulation results demonstrate the effectiveness and robustness of our proposed EGT approach for different populations and speeds, thus reducing the overhead of frequent cluster reformation in VANETs.

Kong, F, Sun, X, Guo, YJ, Leung, VCM, Zhu, Q & Zhu, H 2018, 'Queue-aware power consumption minimization in two-tier heterogeneous networks', IEEE Transactions on Vehicular Technology, vol. 67, no. 9, pp. 8875-8889.
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© 1967-2012 IEEE. In this paper, we study the network average power consumption minimization problem in a two-tier heterogeneous network by optimally tuning the activation ratio of micro base stations (BSs) under the quality of service (QoS) constraints of the network mean queueing delay and the network signal-to-interference ratio (SIR) coverage. With the consideration of dynamic packets arrivals, each BS can either be busy or be idle depending on its queueing status. The network performance is thus critically determined by the traffic intensity of each BS. With the assumption of universal frequency reuse, the average traffic intensity of each tier is characterized by a set of fixed-point equations, which can be solved by a proposed iterative method. By using the approximation that BSs of the same tier have the same SIR coverage, the cumulative distribution function of the traffic intensity of each tier is further obtained. On that basis, the network average power consumption per area, the network mean queueing delay, and the network SIR coverage are characterized. Numerical results demonstrate that if the idle power coefficient is below a certain threshold, then the optimal activation ratio equals the one to minimize the network average power consumption per area; otherwise, the optimal activation ratio can be obtained according to the QoS constraints. It is further shown that universal frequency reuse outperforms spectrum partitioning in terms of both the network average power consumption and the network SIR coverage in the considered scenario.

Kusakunniran, W, Wu, Q, Ritthipravat, P & Zhang, J 2018, 'Hard exudates segmentation based on learned initial seeds and iterative graph cut', COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE, vol. 158, pp. 173-183.
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Lai, W, Ni, W, Wang, H & Liu, RP 2018, 'Analysis of Average Packet Loss Rate in Multi-Hop Broadcast for VANETs', IEEE Communications Letters, vol. 22, no. 1, pp. 157-160.
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© 2017 IEEE. Multi-hop relay can effectively improve the average packet loss rate (PLR) of vehicular ad hoc networks within a particular zone of interest. Challenges arise from analyzing the average PLR affected by distributed relay selections, which depend on the mobility of vehicles, the wireless channel conditions, and media access control (MAC). In this letter, we propose an average PLR analysis model taking into account the above three factors. However, the closed-form expression for the average PLR is intractable mainly due to the multiple integral of the joint distance distribution integrating with the channel conditions and vehicle mobility. An explicit expression for the upper bound of the average PLR is obtained by using Taylor series expansion, Holder's inequality, and the relay probability relaxation, which can facilitate the selection of the parameters at the physical and MAC layers for a better PLR. Simulation results validate our analyses.

Li, HS, Fan, P, Xia, HY, Song, S & He, X 2018, 'The quantum Fourier transform based on quantum vision representation', Quantum Information Processing, vol. 17, no. 12.
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© 2018, Springer Science+Business Media, LLC, part of Springer Nature. Quantum Fourier transform (QFT) plays a key role in many quantum algorithms, but the existing circuits of QFT are incomplete and lacking the proof of correctness. Furthermore, it is difficult to apply QFT to the concrete field of information processing. Thus, we firstly investigate quantum vision representation (QVR) and develop a model of QVR. Then, we design four complete circuits of QFT and inverse QFT and describe the functions of their components. Meanwhile, we prove the correctness of the four complete circuits using formula derivation. Next, 2D QFT and 3D QFT based on QVR are proposed for the first time. Experimental results with simulation show the proposed QFTs are valid and useful in processing quantum images and videos. In conclusion, this paper develops a complete framework of QFT based on QVR and provides a feasible scheme for QFT to be applied in quantum vision information processing.

Li, H-S, Fan, P, Xia, H-Y, Song, S & He, X 2018, 'The multi-level and multi-dimensional quantum wavelet packet transforms.', Scientific reports, vol. 8, no. 1, pp. 13884-13884.
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The classical wavelet packet transform has been widely applied in the information processing field. It implies that the quantum wavelet packet transform (QWPT) can play an important role in quantum information processing. In this paper, we design quantum circuits of a generalized tensor product (GTP) and a perfect shuffle permutation (PSP). Next, we propose multi-level and multi-dimensional (1D, 2D and 3D) QWPTs, including a Haar QWPT (HQWPT), a D4 QWPT (DQWPT) based on the periodization extension and their inverse transforms for the first time, and prove the correctness based on the GTP and PSP. Furthermore, we analyze the quantum costs and the time complexities of our proposed QWPTs and obtain precise results. The time complexities of HQWPTs is at most 6 on 2n elements, which illustrates high-efficiency of the proposed QWPTs. Simulation experiments demonstrate that the proposed QWPTs are correct and effective.

Li, K, Ni, W, Duan, L, Abolhasan, M & Niu, J 2018, 'Wireless Power Transfer and Data Collection in Wireless Sensor Networks', IEEE Transactions on Vehicular Technology, vol. 67, no. 3, pp. 2686-2697.
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© 1967-2012 IEEE. In a rechargeable wireless sensor network, the data packets are generated by sensor nodes at a specific data rate, and transmitted to a base station. Moreover, the base station transfers power to the nodes by using wireless power transfer (WPT) to extend their battery life. However, inadequately scheduling WPT and data collection causes some of the nodes to drain their battery and have their data buffer overflow, whereas the other nodes waste their harvested energy, which is more than they need to transmit their packets. In this paper, we investigate a novel optimal scheduling strategy, called EHMDP, aimin g to minimize data packet loss from a network of sensor nodes in terms of the nodes' energy consumption and data queue state information. The scheduling problem is first formulated by a centralized MDP model, assuming that the complete states of each node are well known by the base station. This presents the upper bound of the data that can be collected in a rechargeable wireless sensor network. Next, we relax the assumption of the availability of full state information so that the data transmission and WPT can be semidecentralized. The simulation results show that, in terms of network throughput and packet loss rate, the proposed algorithm significantly improves the network performance.

Li, L, Liu, Z & Zhang, J 2018, 'Unsupervised image co-segmentation via guidance of simple images', Neurocomputing, vol. 275, pp. 1650-1661.
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© 2017 Elsevier B.V. This paper proposes a novel image co-segmentation method, which aims to segment the common objects in a group of images. The proposed method takes advantages of the reliability of simple images and successfully improves the performance. The images are first ranked by the complexities based on their saliency maps. Then, the simple images, in which objects are common and easy to be segmented, are selected and processed to obtain their segmentation results, these segmentation results are taken as the samples of the targeted objects. Finally, the remaining complicated images are segmented with the guidance of the samples. The experiments on the iCoseg dataset demonstrate the outperformance and robustness of the proposed method.

Li, M, Liu, Y & Guo, YJ 2018, 'Shaped Power Pattern Synthesis of a Linear Dipole Array by Element Rotation and Phase Optimization Using Dynamic Differential Evolution', IEEE ANTENNAS AND WIRELESS PROPAGATION LETTERS, vol. 17, no. 4, pp. 697-701.
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Li, M, Yang, Y, Xu, KD, Zhu, X & Wong, SW 2018, 'Microwave On-Chip Bandpass Filter Based on Hybrid Coupling Technique', IEEE Transactions on Electron Devices, vol. 65, no. 12, pp. 5453-5459.
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© 2018 IEEE. In this paper, a novel on-chip circuit design approach is proposed using hybrid coupling technique. Taking advantage of this technique, a microwave bandpass filter (BPF) is proposed as a design example for proof of concept. Based on stub-loaded stepped-impedance transmission lines and folded stepped-impedance meander line from different metal layers, the proposed BPF can generate three transmission zeros (TZs) and two transmission poles (TPs), which are excited through the hybrid mutual couplings between the inductive and capacitive metals. To understand the principle of this configuration, an equivalent LC-circuit model is presented and simplified, of which the TZs and TPs of the proposed BPF are estimated by the extracted transfer function. The calculated results exhibit good agreements with the simulated and measured ones. In addition, the bandwidth and center frequency of the proposed BPF can be tuned flexibly. Finally, to further demonstrate the feasibility of this approach in practice, the structure is implemented and fabricated in a commercial 0.13- μm SiGe (Bi)-CMOS technology. The measurement results show that the proposed BPF, whose chip size is 0.39 mm × 0.45 mm (excluding the test pads), can realize a wide bandwidth from 19.7 to 33.2 GHz with a return loss of 15.8 dB and insertion loss of 3.8 dB at the center frequency of 26.5 GHz.

Li, W, Liu, BM, Liu, D, Liu, RP, Wang, P, Luo, S & Ni, W 2018, 'Unified Fine-grained Access Control for Personal Health Records in Cloud Computing.', IEEE journal of biomedical and health informatics.
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Attribute-based encryption has been a promising encryption technology to secure personal health records (PHRs) sharing in cloud computing. PHRs consist of the patient data often collected from various sources including hospitals and general practice centres. Different patients' access policies have a common access sub-policy. In this paper, we propose a novel attribute-based encryption scheme for fine-grained and flexible access control to PHRs data in cloud computing. The scheme generates shared information by the common access sub-policy which is based on different patients' access policies. Then the scheme combines the encryption of PHRs from different patients. Therefore, both time consumption of encryption and decryption can be reduced. Medical staff require varying levels of access to PHRs. The proposed scheme can also support multi-privilege access control so that medical staff can access the required level of information while maximizing patient privacy. Through implementation and simulation, we demonstrate that the proposed scheme is efficient in terms of time. Moreover, We prove the security of the proposed scheme based on security of the ciphertext-policy attribute-based encryption scheme.

Li, X, Shankaran, R, Orgun, MA, Fang, G & Xu, Y 2018, 'Resource Allocation for Underlay D2D Communication with Proportional Fairness', IEEE Transactions on Vehicular Technology, vol. 67, no. 7, pp. 6244-6258.
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© 1967-2012 IEEE. As an emerging paradigm, device-to-device (D2D) communication has the capability to complement and enhance the conventional cellular network by offering high spectral and energy efficiency. However, the problem of cochannel interference makes the resource allocation very complex and challenging in underlay D2D communication networks. This paper proposes a novel joint power control and resource scheduling scheme to enhance both the network throughput and the users' fairness of the underlay D2D communication networks. Unlike other previous work in this area, our scheme aims at maximizing the sum of all users' proportional fairness functions, while simultaneously taking into account factors such as fairness, signal-to-interference-plus-noise ratio requirements, and severe interference. The proposed scheme offers a practical solution because it works for lengthy time slots, a realistic scenario for the underlay D2D communication system. We also take into consideration the time-varying feature of user's channel condition in our proposed solution. Numerical results confirm that our proposed scheme not only dramatically improves the system throughput, but also boosts the system fairness while guaranteeing the Quality-of-Service levels of all D2D users and cellular users.

Lian, J-W, Ban, Y-L, Zhu, J-Q, Liu, Y & Kang, K 2018, 'SIW Multibeam Antenna Based on Modified Horn Beam-Forming Network', IEEE ANTENNAS AND WIRELESS PROPAGATION LETTERS, vol. 17, no. 10, pp. 1866-1870.
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Liberal, I, Ederra, I & Ziolkowski, RW 2018, 'Quantum antenna arrays: The role of quantum interference on direction-dependent photon statistics', Physical Review A, vol. 97, no. 5.
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© 2018 American Physical Society. We investigate the role of quantum interference phenomena on the characteristics of the fields radiated by an array of quantum emitters. In analogy to, but distinct from, classical outcomes, we demonstrate that the array geometry empowers control over direction-dependent photon statistics of arbitrary order. Our formulation enables the recognition of configurations providing spatial correlations with no classical counterpart. For example, we identify a system in which the angular distribution of the average number of photons is independent of the number and position of the emitters, while its higher-order photon statistics exhibit a directional behavior. These results extend our understanding of the fields generated by ensembles of quantum emitters, with potential applications to nonclassical light sources.

Lin, C, Ge, Y, Bird, TS & Liu, K 2018, 'Circularly Polarized Horns Based on Standard Horns and a Metasurface Polarizer', IEEE Antennas and Wireless Propagation Letters, vol. 17, no. 3, pp. 480-484.
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© 2017 IEEE. A method for designing circularly polarized (CP) horn antenna is proposed, which is based on a standard pyramidal horn with a linear-to-circular polarization transformer. A compact transparent metasurface transformer is first designed to perform linear-to-circular polarization transformation, and then this is inserted in a linearly polarized standard pyramidal horn to create a CP horn. To validate the CP horn design, both simulations and experiments were conducted and good agreement was obtained. The CP performance achieved a 3 dB axial-ratio bandwidth of 7.4%, a maximum gain reduction of 1.1 dB without altering the horn's original size for a light increase in weight and at a small cost increase.

Lin, JY, Wong, SW, Wu, YM, Zhu, L, Yang, Y & He, Y 2018, 'A New Concept and Approach for Integration of Three-State Cavity Diplexer Based on Triple-Mode Resonators', IEEE Transactions on Microwave Theory and Techniques, vol. 66, no. 12, pp. 5272-5279.
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© 2018 IEEE. A novel concept and approach for integration of a three-state diplexer (TSD) by utilizing the triple-mode cavity resonators is proposed in this paper. The proposed TSD has the inherent nature of three frequency channels, two of which can be utilized for duplexing channels by exciting one port as the input in each state. Meanwhile, three fundamental modes, namely, TE 011 , TE 101 , and TM 110 , are excited in the triple-mode resonators (TMRs) to control these three frequency channels. Without utilizing any junction networks for impedance matching, the required values of the external quality factors and coupling coefficients can be extracted to meet the relevant Chebyshev responses in the three bands of the TSD, simultaneously. Owing to the modal orthogonality among the three fundamental modes, high isolation among these three frequency channels can be effectively achieved. For proof of concept, two design examples of the TSD structures are presented with different topologies. For both examples, four and six TMRs are adopted, respectively, where the predicted three frequency channels of the TSD can be successfully excited with excellent channel isolations. The fabricated prototype shows good agreement between the simulated and measured results verifying the feasibility of the proposed design methodology.

Lin, JY, Wong, SW, Zhu, L, Yang, Y, Zhu, X, Xie, ZM & He, Y 2018, 'A Dual-Functional Triple-Mode Cavity Resonator with the Integration of Filters and Antennas', IEEE Transactions on Antennas and Propagation, vol. 66, no. 5, pp. 2589-2593.
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© 1963-2012 IEEE. A novel concept for the two-in-one design with the integration of filters and antennas, using a single cavity, is presented in this communication. Basically, a triple-mode resonator (TMR) is utilized as a common feeder to achieve filtering and radiating functions at three different frequency bands. Each of the three bands adopts one of the three fundamental modes, namely, TE011, TE101, and TM110, in a single TMR to realize the relevant functions. Owing to the modal orthogonality of these fundamental modes, high isolation can be effectively realized among these three channels. Based on the proposed TMR, three different prototypes are designed for different applications. For the first prototype, the structure of a dual-band filter plus an antenna is presented using a second-order TMR. Based on the combination of a duplexer plus an antenna, the second prototype is attained. To further explore the function of the proposed TMR, the structure of a filter plus a dual-polarization antenna is depicted as the third prototype. For verification, the third prototype is fabricated and tested. Good agreement between the simulated and the measured results is achieved, which proves the feasibility of the proposed design methodology.

Lin, SJ, Yu, JG, Ni, W & Liu, RP 2018, 'Decoupling 5G Network Control: Centralised Coordination and Distributed Adaptation', INTERNATIONAL JOURNAL OF COMPUTERS COMMUNICATIONS & CONTROL, vol. 13, no. 2, pp. 192-204.
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Lin, W & Wong, H 2018, 'Wideband polarization and pattern reconfigurable antennas', Dianbo Kexue Xuebao/Chinese Journal of Radio Science, vol. 33, no. 3, pp. 293-300.
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Copyright © 2018 by Editorial Department of Chinese Journal of Radio Science The research on reconfigurable antennas becomes more and more popular recently along with the rapid development of modern wireless communication systems. Reconfigurable antennas will facilitate to increase the wireless channel capacity, to avoid polarization mismatch, and to enhance the radiation coverage. This paper will present four reconfigurable antenna designs that realize the wideband polarization and pattern reconfigurability. First, a wideband multi-linear polarizations reconfigurable antenna is introduced, that is based on the L-shaped probe fed patch radiators. Multiple L-shaped structure is adopted to realize the reconfigurability. Second, based on the same methodology, a wideband circular polarization reconfigurable antenna is developed via an output switchable power divider. Expect for the polarization reconfigurable antennas, this paper also presents two pattern reconfigurable antennas that achieve switchable conical-beam and broadside radiations. The former one utilizes the combination of a wideband monopolar patch antenna and an L-probe fed patch antenna. The latter one adopts an annular-slotted patch antenna fed by an excitation reconfigurable feed network. All the antennas discussed above exhibit wide bandwidth, low profile, stable realized gain and desired reconfigurability.

Lin, W & Ziolkowski, RW 2018, 'Electrically Small, Low-Profile, Huygens Circularly Polarized Antenna', IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, vol. 66, no. 2, pp. 636-643.
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Lin, W, Chen, SL, Ziolkowski, RW & Guo, YJ 2018, 'Reconfigurable, Wideband, Low-Profile, Circularly Polarized Antenna and Array Enabled by an Artificial Magnetic Conductor Ground', IEEE Transactions on Antennas and Propagation, vol. 66, no. 3, pp. 1564-1569.
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© 1963-2012 IEEE. A reconfigurable, wideband, and low-profile circular polarization (CP) antenna is presented. Its wideband CP reconfigurability is realized by incorporating RF switches into a cross-bowtie radiator. A compact, wide bandwidth, and polarization-independent artificial magnetic conductor ground plane is developed to minimize the overall profile of the antenna while maintaining its wide bandwidth. The simplicity of this single-element design facilitates the realization of a reconfigurable, wide bandwidth CP array that achieves higher directivity without changing its overall profile. Prototypes of the single element and of a 1 × 4 array of these elements were fabricated and tested. The measured results for both prototypes are in good agreement with their simulated values, validating their design principles. They are low profile with a height ∼ 0.05 λ0. The array exhibits a wide fractional operational bandwidth: 1.65 GHz (21.7%), and a high realized gain: 13 dBic. Since they would enhance their channel capacity and avoid polarization mismatch issues, these reconfigurable CP antenna systems are very suitable for modern wireless systems.

Lin, W, Wong, H & Ziolkowski, RW 2018, 'Circularly Polarized Antenna with Reconfigurable Broadside and Conical Beams Facilitated by a Mode Switchable Feed Network', IEEE Transactions on Antennas and Propagation, vol. 66, no. 2, pp. 996-1001.
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© 1963-2012 IEEE. A pattern-reconfigurable slot-augmented patch antenna is reported that radiates circularly polarized (CP) fields and is switchable between a broadside and a conical radiating mode. Two novel design strategies were adopted to realize these advantageous performance characteristics. First, a mode switchable feed network which includes a set of eight L-probes was developed that facilitates the proper excitation of either the patch's TM11 or TM21 mode and yields symmetric radiation patterns. Second, their operating bands were made to overlap by augmenting this patch with an annular slot. Consequently, the radiation pattern is easily switched between the broadside and the conical modes within the overlapping operational bandwidths. A prototype was fabricated and tested. The measured results are in good agreement with their simulated values, verifying the design concepts. The measured operating bandwidth, 7.8% from 2.45 to 2.65 GHz, was determined from the overlap of the impedance and axial ratio bandwidths for both modes. The measured realized gain values are stable for both radiating states within this operational bandwidth, the broadside (conical) peak value being 8.5 dBic (5.8 dBic). The CP pattern reconfigurability of this antenna with its favorable performance characteristics makes it an ideal candidate for many RFID and satellite communication applications.

Liu, Y, Bai, J, Xu, KD, Xu, Z, Han, F, Liu, QH & Jay Guo, Y 2018, 'Linearly Polarized Shaped Power Pattern Synthesis With Sidelobe and Cross-Polarization Control by Using Semidefinite Relaxation', IEEE Transactions on Antennas and Propagation, vol. 66, no. 6, pp. 3207-3212.
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© 1963-2012 IEEE. In this communication, the problem of synthesizing a linearly polarized shaped power pattern with accurate control on both sidelobe and cross-polarization (XP) levels is considered. For a user-defined desired polarization direction, the definitions of realizable co-polarization (COP) and XP directions for an arbitrary propagation direction in the shaped pattern are presented. With the help of such definitions, the considered problem is formulated as finding appropriate excitations so as to produce a shaped power pattern in which the realizable COP component meets prescribed lower and upper bounds, the realizable XP component and the total power pattern are less than their upper bounds in the regions of interest. The semidefinite relaxation method in the literature is then extended to solve this vectorial pattern synthesis problem. The proposed method can include the mutual coupling and platform effects by using vectorial active element patterns of an antenna array. A set of synthesis examples with different array geometries and radiation requirements are conducted to validate the effectiveness and advantages of the proposed method.

Liu, Y, Cheng, J, Xu, KD, Yang, S, Liu, QH & Guo, YJ 2018, 'Reducing the number of elements in the synthesis of a broadband linear array with multiple simultaneous frequency-invariant beam patterns', IEEE Transactions on Antennas and Propagation, vol. 66, no. 11, pp. 5838-5848.
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© 2018 IEEE. The problem of reducing the number of elements in a broadband linear array with multiple simultaneous crossover frequency-invariant (FI) patterns is considered. Different from the single FI pattern array case, every element channel in the multiple FI pattern array is divided and followed by multiple finite-impulse-response (FIR) filters, and each of the multiple FIR filters has a set of coefficients. In this situation, a collective filter coefficient vector and its energy bound are introduced for each element, and then the problem of reducing the number of elements is transformed as minimizing the number of active collective filter coefficient vectors. In addition, the radiation characteristics including beam pointing direction, mainlobe FI property, sidelobe level, and space-frequency notching requirement for each of the multiple patterns can be formulated as multiple convex constraints. The whole synthesis method is implemented by performing an iterative second-order cone programming (SOCP). This method can be considered as a significant extension of the original SOCP for synthesizing broadband sparse array with single FI pattern. Numerical synthesis results show that the proposed method by synthesizing multiple discretized crossover FI patterns can save more elements than the original iterative SOCP by using a single continuously scannable FI pattern for covering the same space range. Moreover, even for multiple FI-patterns case with complicated space-frequency notching, the proposed method is still effective in the reduction of the number of elements.

Luo, Y, Pan, J, Zhang, JA & Huang, S 2018, 'Worst-case performance optimization beamformer with embedded array’s active pattern', International Journal of Antennas and Propagation, vol. 2018.
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Copyright © 2018 Yuyue Luo et al. This paper proposes an adaptive array beamforming method by embedding antennas’ active pattern in the worst-case performance optimization algorithm. This method can significantly reduce the beamformer’s performance degradation caused by inconsistency between hypothesized ideal array models and practical ones. Simulation and measured results consistently demonstrate the robustness and effectiveness of the proposed method in dealing with array manifold mismatches.

Lyu, X, Ni, W, Tian, H, Liu, RP, Wang, X, Giannakis, GB & Paulraj, A 2018, 'Distributed Online Optimization of Fog Computing for Selfish Devices With Out-of-Date Information', IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS, vol. 17, no. 11, pp. 7704-7717.
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Lyu, X, Ren, C, Ni, W, Tian, H & Liu, RP 2018, 'Distributed Optimization of Collaborative Regions in Large-Scale Inhomogeneous Fog Computing', IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS, vol. 36, no. 3, pp. 574-586.
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Lyu, X, Ren, C, Ni, W, Tian, H, Liu, RP & Guo, YJ 2018, 'Multi-Timescale Decentralized Online Orchestration of Software-Defined Networks', IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS, vol. 36, no. 12, pp. 2716-2730.
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Lyu, X, Tian, H, Ni, W, Zhang, Y, Zhang, P & Liu, RP 2018, 'Energy-Efficient Admission of Delay-Sensitive Tasks for Mobile Edge Computing', IEEE Transactions on Communications, vol. 66, no. 6, pp. 2603-2616.
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© 1972-2012 IEEE. Task admission is critical to delay-sensitive applications in mobile edge computing, but is technically challenging due to its combinatorial mixed nature and consequently limited scalability. We propose an asymptotically optimal task admission approach which is able to guarantee task delays and achieve (1 - ∈)-approximation of the computationally prohibitive maximum energy saving at a time-complexity linearly scaling with devices. ∈ is linear to the quantization interval of energy. The key idea is to transform the mixed integer programming of task admission to an integer programming (IP) problem with the optimal substructure by pre-admitting resource-restrained devices. Another important aspect is a new quantized dynamic programming algorithm which we develop to exploit the optimal substructure and solve the IP. The quantization interval of energy is optimized to achieve an [O(∈),O(1/∈)]-tradeoff between the optimality loss and time complexity of the algorithm. Simulations show that our approach is able to dramatically enhance the scalability of task admission at a marginal cost of extra energy, as compared with the optimal branch and bound method, and can be efficiently implemented for online programming.

Ma, X, Liang, J, Liu, R, Ni, W, Li, Y, Li, R, Ma, W & Qi, C 2018, 'A Survey on Data Storage and Information Discovery in the WSANs-Based Edge Computing Systems.', Sensors (Basel, Switzerland), vol. 18, no. 2.
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In the post-Cloud era, the proliferation of Internet of Things (IoT) has pushed the horizon of Edge computing, which is a new computing paradigm with data are processed at the edge of the network. As the important systems of Edge computing, wireless sensor and actuator networks (WSANs) play an important role in collecting and processing the sensing data from the surrounding environment as well as taking actions on the events happening in the environment. In WSANs, in-network data storage and information discovery schemes with high energy efficiency, high load balance and low latency are needed because of the limited resources of the sensor nodes and the real-time requirement of some specific applications, such as putting out a big fire in a forest. In this article, the existing schemes of WSANs on data storage and information discovery are surveyed with detailed analysis on their advancements and shortcomings, and possible solutions are proposed on how to achieve high efficiency, good load balance, and perfect real-time performances at the same time, hoping that it can provide a good reference for the future research of the WSANs-based Edge computing systems.

Ma, X, Liu, Y, Da Xu, K, Zhu, C & Liu, QH 2018, 'Synthesising multiple-pattern sparse linear array with accurate sidelobe control by the extended reweighted L1-norm minimisation', Electronics Letters, vol. 54, no. 9, pp. 548-550.
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© The Institution of Engineering and Technology 2018. The problem of synthesising a sparse linear array with multiple patterns is formulated as an extended reweighted ℓ1-norm minimisation with multiple convex constraints. Synthesis results show that the proposed method can find the common sparse element positions with optimised excitations for multiple-pattern requirements, and the mainlobe, sidelobe as well as nulling region for each pattern can be accurately controlled.

Mezzadri, F, Janzen, FC, Martelli, G, Canning, J, Cook, K & Martelli, C 2018, 'Optical-Fiber Sensor Network Deployed for Temperature Measurement of Large Diesel Engine', IEEE Sensors Journal, vol. 18, no. 9, pp. 3654-3660.
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© 2001-2012 IEEE. This paper presents a method to measure the temperature of the fixed and mobile bearings of a crankshaft in a large diesel engine using optical fiber Bragg gratings (FBGs). The FBG sensor development and the encapsulation with stainless-steel tube are described. The sensors were tested in a large diesel engine in full operation and the results demonstrate the efficiency of the proposed temperature measurement method in monitoring the crankshaft bearings. It is possible to anticipate fault signals with proper processing of temperature data.

Mishra, SK, Puthal, D, Rodrigues, JJPC, Sahoo, B & Dutkiewicz, E 2018, 'Sustainable Service Allocation Using a Metaheuristic Technique in a Fog Server for Industrial Applications', IEEE Transactions on Industrial Informatics, vol. 14, no. 10, pp. 4497-4506.
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© 2005-2012 IEEE. Reducing energy consumption in the fog computing environment is both a research and an operational challenge for the current research community and industry. There are several industries such as finance industry or healthcare industry that require a rich resource platform to process big data along with edge computing in fog architecture. As a result, sustainable computing in a fog server plays a key role in fog computing hierarchy. The energy consumption in fog servers depends on the allocation techniques of services (user requests) to a set of virtual machines (VMs). This service request allocation in a fog computing environment is a nondeterministic polynomial-time hard problem. In this paper, the scheduling of service requests to VMs is presented as a bi-objective minimization problem, where a tradeoff is maintained between the energy consumption and makespan. Specifically, this paper proposes a metaheuristic-based service allocation framework using three metaheuristic techniques, such as particle swarm optimization (PSO), binary PSO, and bat algorithm. These proposed techniques allow us to deal with the heterogeneity of resources in the fog computing environment. This paper has validated the performance of these metaheuristic-based service allocation algorithms by conducting a set of rigorous evaluations.

Movassaghi, S, Smith, DB, Abolhasan, M & Jamalipour, A 2018, 'Opportunistic spectrum allocation for interference mitigation amongst coexisting wireless body area networks', ACM Transactions on Sensor Networks, vol. 14, no. 2.
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© 2018 ACM. Wireless Body Area Networks (WBANs) are seen as the enabling technology for developing new generations of medical applications, such as remote health monitoring. As such it is expected that WBANs will predominantly transport mission-critical and delay sensitive data. A key strategy towards building a reliable WBAN is to ensure such networks are highly immune to interference. To achieve this, new and intelligent wireless spectrum allocation strategies are required not only to avoid interference, but also to make best-use of the limited available spectrum. This article presents a new spectrum allocation scheme referred to as Smart Channel Assignment (SCA), which maximizes the resource usage and transmission speed by deploying a partially-orthogonal channel assignment scheme between coexisting WBANs as well as offering a convenient tradeoff among spectral reuse efficiency, transmission rate, and outage. Detailed analytical studies verify that the proposed SCA strategy is robust to variations in channel conditions, increase in sensor node-density within each WBAN, and an increase in number of coexisting WBANs.

Mueller, A, Ziolkowski, RW, Kim, J, Blokhina, E, Dragoman, M & Bozzi, M 2018, 'Special Section Proposal Tunable Devices for Modern Communications: Materials, Integration, Modeling, and Applications', IEEE ACCESS, vol. 6, pp. 42368-42372.
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Nan, Y, Huang, X & Guo, YJ 2018, 'Generalized Continuous Wave Synthetic Aperture Radar for High Resolution and Wide Swath Remote Sensing', IEEE Transactions on Geoscience and Remote Sensing, vol. 56, no. 12, pp. 7217-7229.
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Nguyen, DN, Dutkiewicz, E & Krunz, MM 2018, 'Harvesting Short-lived White Spaces via Opportunistic Traffic Offloading between Mobile Service Providers', IEEE Transactions on Cognitive Communications and Networking, vol. 4, no. 3, pp. 635-647.
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Currently, Wi-Fi (IEEE 802.11) is the most widely adopted wireless technology for mobile traffic offloading at hot spots. Despite its great success, Wi-Fi is constrained by the over-crowded unlicensed spectrum, which leads to poor user experience, especially in urban areas. This paper introduces an opportunistic cooperation framework that allows mobile service providers (MSPs) to offload traffic onto each other's network by harvesting short-lived spectrum/resources of cellular systems. Specifically, through traffic offloading, MSPs aim to maximize their profit while maintaining their quality of service (QoS) commitments. For that purpose, we model the strategic cooperation between MSPs as a stochastic Markov game in which the dynamics of resource availability and user behaviors are captured via a Markov decision process. We prove that the game is irreducible and admits a Nash Equilibrium at which all MSPs benefit from traffic offloading. A practical algorithm that uses only local information to govern traffic offloading at MSPs is then developed. Numerical simulations show that by designing appropriate profit sharing contracts, our proposed algorithm can achieve almost the same performance as that of a socially optimal solution. The derived traffic offloading strategies not only improve QoS and revenue for MSPs, but also can be used to guide MSPs on when to turn off their base stations while the traffic volume is light (e.g., during nighttime).

Nguyen, DN, Krunz, M & Dutkiewicz, E 2018, 'Full-duplex MIMO Radios: A Greener Networking Solution', IEEE Transactions on Green Communications and Networking, vol. 2, no. 3, pp. 652-665.
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Nguyen, DTN, Teo, STT, Grover, SL & Nguyen, NP 2018, 'Respect, bullying, and public sector work outcomes in Vietnam', Public Management Review.
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© 2018, © 2018 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group. This article examines empirical links between a subordinate’s felt recognition respect from his/her supervisor, the subordinate’s appraisal respect for that supervisor, and bullying, work engagement, and organizational citizenship behaviour in Vietnam’s public sector. Data from 274 employees in six branches of a public sector agency were used to test the hypothesized model. Within Vietnam’s public sector, the followers who receive recognition respect from the leaders have greater appraisal respect for their leaders, experience less bullying, and reveal higher work engagement and organizational citizenship behaviour. This article theoretically and empirically contributes to the respect literature developed in the Western context.

Ni, W, Zhang, A, Fang, Z, Abolhasan, M, Liu, RP & Guo, YJ 2018, 'Analysis of Finite Buffer in Two-Way Relay: A Queueing Theoretic Point-of-View', IEEE Transactions on Vehicular Technology, vol. 67, no. 4, pp. 3690-3694.
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IEEE The impact of a finite relay buffer on the throughput of two-way relay is analyzed from a new queueing theoretic point-of-view. Distinctively from recent Markov model based analyses, the proposed queueing theoretic analysis is able to infer closed-form expressions, shed valuable insights, and point out limitations in existing analyses based on Markov models. Validated by simulations, our queueing theoretic analysis reveals that the throughput is increasingly insusceptible to the size of the relay buffer, as the buffer enlarges. Moreover, locking the relay in transmitting XORed packets can hardly improve the throughput, especially under balanced channel conditions. This is due to the fact that the relay queues are stabilized non-empty and hence, XORed packets are forwarded in most cases.

Niazi, M, Mishra, A & Gill, AQ 2018, 'What Do Software Practitioners Really Think About Software Process Improvement Project Success? An Exploratory Study', Arabian Journal for Science and Engineering, vol. 43, no. 12, pp. 7719-7735.
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© 2018, King Fahd University of Petroleum & Minerals. Software practitioners have always shown a significant interest in implementing software process improvement (SPI) initiatives to ensure the delivery of quality products. Software industry and SPI methodologies have evolved over a period of time; however, still many SPI initiatives have not been successful. There is a need to understand software practitioners’ perspectives on SPI success which can be helpful for tailoring or improving effective situation-specific SPI methodologies. This research presents an exploratory study of Turkish software development organizations. The main research question is: What software practitioners’ really think about SPI project success. This study was conducted with 27 Turkish software development organizations to identity and analyse important SPI factors that contribute to the success of SPI projects. The results reveal that professional growth, increased professional recognition, project planning, monitoring of project risks, providing technical support, adoption of current technologies, strong leadership and commitment are among the highest ranked factors that contribute towards the success of SPI initiatives. The findings of this research provide a foundation for further work in tailoring and improving situation-specific SPI methodologies for software project environments.

Nicholson, KJ, Baum, TC, Ziolkowski, RW, Ghorbani, K & Bain, G 2018, 'Tomographic Characterization of a Multifunctional Composite High-Impedance Surface', IEEE Transactions on Microwave Theory and Techniques, vol. 66, no. 6, pp. 2904-2913.
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© 1963-2012 IEEE. The performance of a multifunctional composite high-impedance surface (HIS) has been evaluated using the coherent Doppler tomography (CDT) and finite-impulse response (FIR) filtering techniques. A combination of embroidery and advanced laser manufacturing processes were used to fabricate the conformable multifunctional glass fiber reenforced polymer HIS. The CDT method was utilized because it enabled the generation of a high-resolution tomographic map of the HIS reflectivity. Tomograms generated at high incidence angles (>80° from normal) were used to localize and FIR filter unwanted scattering associated with the ground plane edges and HIS transition regions. The resulting scattered fields from a defect (metallic block positioned in the center of the tomogram) were then used to gain a significantly distinctive insight into the HIS scattering properties. Furthermore, unlike traditional methods for characterizing HISs, the CDT and FIR methods presented herein are applicable to electrically large and conformal HISs.

Pham, T, Farrell, R, Dooley, J, Dutkiewicz, Nguyen, D & Le-Nam Tran 2018, 'Efficient Zero-forcing Precoder Design for Weighted Sum-rate Maximization with Per-antenna Power Constraint', IEEE Transactions on Vehicular Technology, vol. 67, no. 4, pp. 3640-3645.
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This paper proposes an efficient (semi-closed-form) zero-forcing (ZF) precoder design for the weighted sum-rate maximization problem under per-antenna power constraint (PAPC). Existing approaches for this problem are based on either interior-point methods that do not favorably scale with the problem size or subgradient methods that are widely known to converge slowly. To address these shortcomings, our proposed method is derived from three elements: minimax duality, alternating optimization (AO), and successive convex approximation (SCA). Specifically, the minimax duality is invoked to transform the considered problem into an equivalent minimax problem, for which we then recruit AO and SCA to find a saddle point, which enables us to take advantages of closed-form expressions and hence achieve fast convergence rate. Moreover, the complexity of the proposed method scales linearly with the number of users, compared to cubically for the standard interior-point methods. We provide an analytical proof for the convergence of the proposed method and numerical results to demonstrate its superior performance over existing approaches. Our proposed method offers a powerful tool to characterize the achievable rate region of ZF schemes under PAPC for massive multiple-input multiple-output.

Pham, TT, Nguyen, D, Dutkiewicz, E, Center, JR, Eisman, JA & Nguyen, T 2018, 'A Profiling analysis of contributions of cigarette smoking, dietary calcium intakes, and physical activity to fragility fracture in the elderly', Nature Scientific Reports, vol. 8, no. 1.
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Pupatwibul, P, Banjar, AR, Hossain, MI, Braun, R & Moulton, B 2018, 'A Novel Software-Defined Networking Controller: the Distributed Active Information Model (DAIM)', International Journal of Electronics and Telecommunications, vol. 64, pp. 209-216.
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Qin, C, Ni, W, Tian, H, Liu, RP & Guo, YJ 2018, 'Joint Beamforming and User Selection in Multiuser Collaborative MIMO SWIPT Systems with Non-negligible Circuit Energy Consumption', IEEE Transactions on Vehicular Technology, vol. 67, no. 5, pp. 3909-3923.
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IEEE Multi-antenna beamforming has potential to improve the efficiency of simultaneous wireless information and power transfer (SWIPT). Existing designs are focused on the downlink of multiple-input-single-output under the assumption of single-antenna users and negligible energy consumption in users’ circuitry, despite the fact that using multiple antennas on the user side can further improve system efficiency. In this paper, novel multiuser collaborative multiple-input-multiple-output (MIMO) SWIPT systems are studied under the assumption of non-negligible circuit energy consumption. Particularly, we convexify and maximize the uplink sum rate of active users, while maintaining the quality of service (QoS) of their downlink data. The beamformers and durations of both links, and the power splitting factors of individual users are jointly optimized, using semidefinite programming and golden search. Further, the selection of active users is optimized, where all users are assumed to be active in the beginning and those detrimental to the sum-rate maximization are continually deactivated. Evident from simulations, the proposed approaches can eliminate the need for computationally prohibitive combinatorial integer programming at a marginal cost of the sum rate.

Qin, P, Chen, S & Guo, YJ 2018, 'Recent Advances in Reconfigurable Antennas at University of Technology Sydney', Journal of Communications and Information Networks, vol. 3, no. 1, pp. 15-20.
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Qin, PY, Ji, LY, Chen, SL & Guo, YJ 2018, 'Dual-Polarized Wideband Fabry-Perot Antenna with Quad-Layer Partially Reflective Surface', IEEE Antennas and Wireless Propagation Letters, vol. 17, no. 4, pp. 551-554.
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© 2002-2011 IEEE. A new quad-layer partially reflective surface (PRS) is presented in this letter for dual-polarized Fabry-Perot (FP) cavity antennas with an improved gain bandwidth. Four layers of metallic square rings are printed on each side of two dielectric substrates separated by an air gap of about λ/27 (λ is the wavelength in the open air) at 5.5 GHz. The total profile of the FP cavity is about λ /2. By properly choosing the dimensions of square rings and the distance between the two substrates, the phase of the reflection coefficient of the PRS increases with the operating frequency, demonstrating a broadband property. In order to validate the performance of the proposed PRS, a dual-polarized FP antenna is designed, which has peak realized gains of 14.7 and 15.5 dBi with 1 dB bandwidths of more than 10% for two polarizations. Furthermore, the input reflection coefficients are lower than -15 dB in the 5.05-5.8 GHz band, and the isolation of the dual-polarized modes is more than 30 dB.

Qumer Gill, A, Loumish, A, Riyat, I & Han, S 2018, 'DevOps for information management systems', VINE Journal of Information and Knowledge Management Systems, vol. 48, no. 1, pp. 122-139.
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© 2018, Emerald Publishing Limited. Purpose: Development and operations (DevOps) is complex in nature. Organizations are unsure how to effectively establish a DevOps capability for the continuous delivery of information management systems. This paper aims to compile and analyze DevOps by applying the well-known systematic literature review (SLR) approach. This review is intended to provide a knowledge base to support the informed, effective and less risky adoption of DevOps for information management systems. Design/methodology/approach: In this qualitative research study, the SLR method was applied to identify 3,790 papers, of which, 32 relevant papers were selected and reviewed. Findings: The results are organized using the well-known ISO/IEC 24744 metamodel elements: people (roles), process, technology and artifacts. In total 11 major roles, 6 processes, 23 technologies, 5 artifacts and 7 challenges (including 6 corresponding solutions) were found. DevOps engineer is becoming a newly identified role. Continuous delivery pipeline and continuous improvement are the most highlighted major DevOps processes. Build system technology is becoming the key focus of DevOps. Finally, major challenges are around people and culture and the misunderstanding of DevOps. Potential research areas are: DevOps analytics, artifacts and tool–chain integration. Research limitations/implications: The research findings will serve as a resource for both practitioners and researchers who have interest in the research and adoption of DevOps for information management systems. Originality/value: This paper provides a comprehensive systematic review of the body of knowledge to support the ongoing research and adoption of emerging trends of DevOps for information management systems.

Rao, T, Xu, M & Liu, H 2018, 'Generating affective maps for images', Multimedia Tools and Applications, vol. 77, no. 13, pp. 17247-17267.
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© 2017, Springer Science+Business Media, LLC. Affective image analysis, which estimates humans’ emotion reflection on images, has attracted increasing attention. Most of the existing methods focus on developing efficient visual features according to theoretical and empirical concepts, and extract these features from an image as a whole. However, analyzing emotion from an entire image, can only extract the dominant emotion conveyed by the whole image, which ignores the affective differences existing among different regions within the image. This may reduce the performance of emotion recognition, and limit the range of possible applications. In this paper, we are the first to propose the concept of affective map, by which image emotion can be represented at region-level. In an affective map, the value of each pixel represents the probability of the pixel belonging to a certain emotion category. Two popular application exemplars, i.e. affective image classification and visual saliency computing, are explored to prove the effectiveness of the proposed affective map. Analyzing detailed image emotion at a region-level, the accuracy of affective image classification has been improved 5.1% on average. The Area Under the Curve (AUC) of visual saliency detection has been improved 15% on average.

Rouzbehi, K, Yazdi, SSH & Moghadam, NS 2018, 'Power Flow Control in Multi-Terminal HVDC Grids Using a Serial-Parallel DC Power Flow Controller', IEEE ACCESS, vol. 6, pp. 56934-56944.
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Shariati, N, Scott, JR, Schreurs, D & Ghorbani, K 2018, 'Multi-tone Excitation Analysis in RF Energy Harvesters -Considerations and Limitations', IEEE Internet of Things Journal, vol. 5, no. 4, pp. 2804-2816.
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The effect of multitone excitation on the dc response of a voltage-doubler radio frequency energy harvester is analyzed. Theoretical analysis as well as frequency and time domain (TD) simulations were conducted to clarify the findings. Measurements were also carried out to validate the results. The measured, simulations and theoretical results are in good agreement. This paper focuses on evaluating the performance of a voltage doubler rectifier under multitone excitation (input power is the same in the single-tone and multitone case). Based on TD and harmonic balance simulations, theoretical and measurement analyses, it is evident that the application of multiple tones simultaneously within the matched frequency band and with the same average available power results in a lower average output dc power when compared with the single-tone case with the same input power. This trend is evident over a broad low input power range of -50 to -10 dBm (0.01-100 μW).

Shen, W, Wu, Y, Yuan, J, Duan, L, Zhang, J & Jia, Y 2018, 'Robust Distracter-Resistive Tracker via Learning a Multi-Component Discriminative Dictionary', IEEE Transactions on Circuits and Systems for Video Technology.
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IEEE Discriminative dictionary learning (DDL) provides an appealing paradigm for appearance modeling in visual tracking. However, most existing DDL based trackers cannot handle drastic appearance changes, especially for scenarios with background cluster and/or similar object interference. One reason is that they often suffer from the loss of subtle visual information which is critical to distinguish an object from distracters. In this paper, we explore the use of deep features extracted from the Convolutional Neural Networks (CNNs) to improve the object representation and propose a robust distracter-resistive tracker via learning a multi-component discriminative dictionary. The proposed method exploits both the intra-class and the interclass visual information to learn shared atoms and the classspecific atoms. By imposing several constraints into the objective function, the learned dictionary is reconstructive, compressive and discriminative, thus can better distinguish an object from the background. In addition, our convolutional features (deep features extracted from CNNs) have structural information for object localization and balance the discriminative power and semantic information of the object. Tracking is carried out within a Bayesian inference framework where a joint decision measure is used to construct the observation model. To alleviate the drift problem, the reliable tracking results obtained online are accumulated to update the dictionary. Both the qualitative and quantitative results on the CVPR2013 benchmark, the VOT2015 dataset and the SPOT dataset demonstrate that our tracker achieves better performance over the state-of-the-art approaches.

Shi, L, Yang, T, Cai, K, Chen, P & Guo, T 2018, 'On MIMO Linear Physical-Layer Network Coding: Full-Rate Full-Diversity Design and Optimization', IEEE Transactions on Wireless Communications, vol. 17, no. 5, pp. 3498-3511.
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© 2002-2012 IEEE. This paper considers a multiuser communication network, where a receiver is set to compute functions of the messages from K users. All user nodes and the receiver are equipped with multi-antenna. We propose a space-time (ST) coded multiple-input multiple-output (MIMO) linear physical-layer network coding (LPNC) scheme that promises full-rate and full-diversity, while achieving the maximum coding gain of LPNC. In the proposed framework, the users' messages are encoded by the same linear dispersion ST code and transmitted simultaneously. The receiver exploits the MIMO LPNC mapping in reconstructing an arbitrary number of linearly network-coded (NC) messages. We derive the NC generator matrix that leads to the greatest coding gain and minimized error probability at the receiver. On top of that, we analytically show that the proposed ST coded LPNC scheme guarantees the full-diversity and full-rate transmission. The proposed method applies to a wide range of network configurations. Two case studies on: (1) MIMO two-way relay network and (2) MIMO multiple-access relay network are presented in this paper. For both case studies, numerical results are shown to demonstrate the performance improvement of the proposed scheme over conventional schemes by more than 4 dB, while the full-rate and full-diversity behaviors are in line with our analysis.

Simorangkir, RBVB, Yang, Y, Esselle, KP & Zeb, BA 2018, 'A Method to Realize Robust Flexible Electronically Tunable Antennas Using Polymer-Embedded Conductive Fabric', IEEE Transactions on Antennas and Propagation, vol. 66, no. 1, pp. 50-58.
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© 1963-2012 IEEE. A new approach to realize robust, flexible, and electronically tunable wearable antennas is presented. Conductive fabric is used to form the conducting parts of the antenna on a polydimethylsiloxane (PDMS) substrate. Then the antenna and the lumped (active and passive) elements, required for electronic tuning and RF choking, are fully encapsulated with additional layers of PDMS. As a concept demonstration, a new frequency-reconfigurable antenna has been designed and fabricated. The details of the prototype manufacturing process are described. Two UWB human muscle equivalent phantoms were also fabricated for testing purposes. Furthermore, the antenna was subjected to several investigations on its RF performance (both in free space and on a flat phantom) and mechanical stability. The latter includes bending tests on several locations on a human-body shaped phantom and washing in a household washing machine. Good agreement between predicted and experimental results (both in free space and on the phantom) is observed, validating the proposed concept. The tests demonstrated that lumped components and other antenna parts remained intact and in working order even under extreme bending (to a bending radius of 28 mm) and after washing, thus maintaining the overall antenna performance including good frequency reconfigurability from 2.3 to 2.68 GHz. To the best of our knowledge, all these features have never been demonstrated in previously published electronically tunable antennas.

Simorangkir, RBVB, Yang, Y, Hashmi, RM, Bjorninen, T, Esselle, KP & Ukkonen, L 2018, 'Polydimethylsiloxane-Embedded Conductive Fabric: Characterization and Application for Realization of Robust Passive and Active Flexible Wearable Antennas', IEEE Access, vol. 6, pp. 48102-48112.
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© 2013 IEEE. We present our study on polydimethylsiloxane (PDMS)-embedded conductive fabric, which we propose as a simple yet effective solution to the challenging issue of poor PDMS-metal adhesion, allowing for a relatively easy realization of robust flexible antennas for wearable applications. The method combines the use of conductive fabric as a radiator with PDMS, which acts as the substrate and a protective encapsulation simultaneously. For the first time, a holistic study on the mechanical and electrical properties of the proposed combination of materials is presented thoroughly using a number of fabricated samples. As concept demonstrations, a microstrip patch and a reconfigurable patch antenna are fabricated using the proposed technique to validate the idea. The inclusion of a PDMS-ceramic composite as part of the antenna's substrate, which leads to over 50% reduction in the size compared with a pure PDMS, is also demonstrated to showcase further the versatility of the proposed technique. The fabricated antennas are tested in several wearable scenarios and consistent performance including reconfigurability is obtained even after the antennas are exposed to harsh environments, i.e., extreme bending and machine-washing.

Siyari, P, Krunz, M & Nguyen, D 2018, 'Power Games for Secure Communications in Single-stream MIMO Interference Networks', IEEE Transactions on Wireless Communications, vol. 17, no. 9, pp. 5759-5773.
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We propose a distributed interference management method for a single-stream MIMO interference network that is tapped by an external eavesdropper. Along with its information signal, each legitimate transmitter creates a bogus signal, known as transmit-based friendly jamming (TxFJ), to confuse the eavesdropper. Although generating TxFJ protects the link from eavesdropping, it creates interference at other unintended but legitimate links. Using non-cooperative game theory, we design a distributed method for maximizing the sum of secrecy rates. Each link is a player in the game. It seeks to maximize its secrecy rate subject to a given information-rate constraint and power budget. The strategy profile of each player is to control the amount of TxFJ it generates. Because a pure non-cooperative game may not have Nash equilibria that result in (Pareto-)optimal secrecy sum-rate, we propose a modified price-based game, in which each link is penalized for generating interference on other legitimate links. Under the exact knowledge of eavesdropping channels, we show that the price-based game has a comparable secrecy sum-rate to a centralized approach. We then relax the assumption of knowledge of eavesdropping channels and leverage mixed-strategy games to provide robust solutions to the distributed secrecy sum-rate maximization problem.

Soldani, D, Guo, YJ, Barani, B, Mogensen, P, I, C-L & Das, SK 2018, '5G FOR ULTRA-RELIABLE LOW-LATENCY COMMUNICATIONS', IEEE NETWORK, vol. 32, no. 2, pp. 6-7.
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Song, Z, Chu, Q, Ye, L, Liu, Y, Zhu, C & Liu, QH 2018, 'High-performance polarization beam splitter based on anisotropic plasmonic nanostructures', Applied Physics B: Lasers and Optics, vol. 124, no. 9.
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© 2018, Springer-Verlag GmbH Germany, part of Springer Nature. We propose an alternative design of efficient and compact polarization beam splitters for wide-angle and polarization-sensitive incidence of electromagnetic waves at near-infrared frequencies. The designed system is constructed by depositing periodic metallic strips on top and bottom of a continuous metal film. Based on the optimization of structure parameters, the whole system can suppress transmission (~ 0%) for one polarization and enhance transmission for another polarization (~ 95%). This phenomenon of anisotropic transmission can be attributed to different performances of impedance along different polarization directions. This device may find applications in optical components and polarization filter.

Sun, HH, Zhu, H, Ding, C & Guo, YJ 2018, 'Wideband Planarized Dual-Linearly-Polarized Dipole Antenna and Its Integration for Dual-Circularly-Polarized Radiation', IEEE Antennas and Wireless Propagation Letters, vol. 17, no. 12, pp. 2289-2293.
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© 2002-2011 IEEE. A planarized dual-linearly-polarized (dual-LP) antenna and an integrated dual-circularly-polarized (dual-CP) antenna are proposed in this letter. For the dual-LP antenna, two groups of dipoles are fed by two balun-included feed networks to achieve ±45° polarizations. The feed networks and the radiators are printed on two sides of a substrate, forming a fully planar structure. Taking advantage of its planar configuration, the dual-LP antenna is further integrated with a wideband coupler to realize dual-CP radiation. The coupler is bent and squeezed into the space between the radiators and the reflector, leading to a compact structure. Both the dual-LP antenna and the dual-CP antenna have very stable radiation performances across a wide operating band >66%.

Sutton, G, Zeng, J, Liu, R, Ni, W, Nguyen, D, Jayawickrama, B, Huang, X, Abolhasan, M & Zhang, Z 2018, 'Enabling Ultra-Reliable and Low Latency Communications through Unlicensed Spectrum', IEEE Network, vol. 32, no. 2, pp. 70-77.
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In this article, we aim to address the question of how to exploit the unlicensed spectrum to achieve URLLC. Potential URLLC PHY mechanisms are reviewed and then compared via simulations to demonstrate their potential benefits to URLLC. Although a number of important PHY techniques help with URLLC, the PHY layer exhibits an intrinsic trade-off between latency and reliability, posed by limited and unstable wireless channels. We then explore MAC mechanisms and discuss multi-channel strategies for achieving low-latency LTE unlicensed band access. We demonstrate, via simulations, that the periods without access to the unlicensed band can be substantially reduced by maintaining channel access processes on multiple unlicensed channels, choosing the channels intelligently, and implementing RTS/CTS.

Sutton, GJ, Liu, RP & Guo, YJ 2018, 'Delay and Reliability of Load-Based Listen-Before-Talk in LAA', IEEE Access, vol. 6, pp. 6171-6182.
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© 2013 IEEE. With the release of the 5 GHz unlicensed spectrum has emerged licensed-Assisted access, in which long-Term evolution (LTE) operators compete with Wi-Fi users for a share of the unlicensed spectrum so as to augment their licensed spectrum. Subsequently, there has been the need to develop a LTE channel access mechanism that enables harmonious coexistence between Wi-Fi and LTE. Load-based listen-before-Talk (LB-LBT) has been adopted as this LTE channel access mechanism by the 3rd Generation Partnership Project (3GPP). Theoretical modelling of LB-LBT schemes has focused on throughput and fair channel-Time sharing between Wi-Fi and LTE technologies. We explore a LB-LBT scheme that belongs to LBT category 4, as recommended by the 3GPP, and develop a model for the distribution of the medium access control (MAC) delays experienced by the Wi-Fi packets and LTE frames. The model, validated by simulations, reveals design insights that can be used to dynamically adjust the LB-LBT parameters not only to achieve channel-Time fairness, but also to guarantee MAC-delay bounds, with specified probability.

Takalkar, M, Xu, M, Wu, Q & Chaczko, Z 2018, 'A survey: facial micro-expression recognition', Multimedia Tools and Applications, vol. 77, no. 15, pp. 19301-19325.
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© 2017 Springer Science+Business Media, LLC Facial expression recognition plays a crucial role in a wide range of applications of psychotherapy, security systems, marketing, commerce and much more. Detecting a macro-expression, which is a direct representation of an ‘emotion,’ is a relatively straight-forward task. Playing a pivotal role as macro-expressions, micro-expressions are more accurate indicators of a train of thought or even subtle, passive or involuntary thoughts. Compared to macro-expressions, identifying micro-expressions is a much more challenging research question because their time spans are narrowed down to a fraction of a second, and can only be defined using a broader classification scale. This paper is an all-inclusive survey-cum-analysis of the various micro-expression recognition techniques. We analyze the general framework for micro-expression recognition system by decomposing the pipeline into fundamental components, namely face detecting, pre-processing, facial feature detection and extraction, datasets, and classification. We discuss the role of these elements and highlight the models and new trends that are followed in their design. Moreover, we provide an extensive analysis of micro-expression recognition systems by comparing their performance. We also discuss the new deep learning features that can, in the near future, replace the hand-crafted features for facial micro-expression recognition. This survey has been developed, focusing on the methodologies applied, databases used, performance regarding recognition accuracy and comparing these to distil the gaps in the efficiencies, future scope, and research potentials. Through this survey, we intend to look into this problem and develop a comprehensive and efficient recognition scheme. This study allows us to identify open issues and to determine future directions for designing real-world micro-expression recognition systems.

Tang, J, Liu, H, Zhang, Q, Ren, B & Liu, Y 2018, 'Miniaturized Multiband HTS Bandpass Filter Design Using a Single-Perturbed Multimode Resonator with Multitransmission Zeros', IEEE Transactions on Applied Superconductivity, vol. 28, no. 4.
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© 2018 IEEE. This paper presents a miniaturized quint-band high-temperature superconducting (HTS) bandpass filter (BPF) based on a single-perturbed multimode resonator (PMMR). By properly adjusting the lengths and the position of the perturbation line in a PMMR, the intrinsic resonance modes can be controlled, which is advantageous for multiband design. The source-load coupling, spurlines, and matching stubs on feedlines are introduced to improve impedance matching and to generate multitransmission zeros, so that enhanced isolation and harmonics suppression can be realized. A low insertion loss (IL) within each band is obtained by using an HTS technology. The filter is fabricated on an MgO substrate with the YBCO thin films, and measured at the temperature of 77 K. The passband measurement is consistent with the simulation, which verifies five passbands located at 0.56, 1.52, 3.8, 4.7, and 5.3 GHz, respectively. A low-measured IL with less than 0.2 dB level is obtained due to the application of a superconducting technology. The proposed HTS BPF owns the great merits of a simple structure, a miniature size (0.008λg2), an enhanced upper stopband, and a low IL.

Tang, MC, Chen, X, Li, M & Ziolkowski, RW 2018, 'Particle swarm optimized, 3-d-printed, wideband, compact hemispherical antenna', IEEE Antennas and Wireless Propagation Letters, vol. 17, no. 11, pp. 2031-2035.
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© 2002-2011 IEEE. A three-dimensional (3-D)-printed, wideband, compact hemispherical-shaped antenna is presented. It consists of a driven strip monopole and several parallel near-field resonant parasitic (NFRP) strips that reside on the surfaces of a hemispherical shell. The monopole strip lies on the interior surface; the NFRP strips lie on the exterior one. This arrangement facilitates the requisite stable near-field capacitive coupling between them over a wide frequency range. The particle swarm optimization algorithm is used to define the lengths and locations of these NFRP strips to achieve its optimized operational bandwidth around 700 MHz given its compact size. The hemispherical shell was 3-D printed with acrylonitrile butadiene styrene resin; the strips were applied to it with silver paste. This prototype was tested. The measured results, in agreement with their simulated values, demonstrate that it achieves a 17.97% -10 dB fractional impedance bandwidth over which stable realized gain values, near 3.5 dBi, are attained. With its low-cost fabrication and attractive performance characteristics, this 3-D printed antenna is suitable for indoor multipath wireless communication systems.

Tang, MC, Chen, Y, Shi, T & Ziolkowski, RW 2018, 'Bandwidth-enhanced, compact, near-field resonant parasitic filtennas with sharp out-of-band suppression', IEEE Antennas and Wireless Propagation Letters, vol. 17, no. 8, pp. 1483-1487.
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© 2002-2011 IEEE. The designs, simulations, and measurements of a class of compact, bandwidth-enhanced filtennas are reported. Our design strategy is illustrated by separately designing a monopole and a bandpass filter to operate primarily in their respective fundamental modes. By combining these elements and manipulating the mutual coupling between them, an enhanced impedance bandwidth filtenna is realized. This strategy is applied to augment metamaterial-inspired near-field resonant parasitic antennas with filters. Simulations of these filtenna systems demonstrate that one can maintain stable radiation performance characteristics no matter how one arranges their component configurations, i.e., their relative positions and orientations. A selected filtenna design prototype was fabricated and tested. The good agreement between the simulated and measured results validates these design principles.

Tang, M-C, Wu, Z, Shi, T & Ziolkowski, RW 2018, 'Electrically Small, Low-Profile, Planar, Huygens Dipole Antenna With Quad-Polarization Diversity', IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, vol. 66, no. 12, pp. 6772-6780.
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Tang, MC, Wu, Z, Shi, T, Zeng, H, Lin, W & Ziolkowski, RW 2018, 'Dual-linearly polarized, electrically small, low-profile, broadside radiating, huygens dipole antenna', IEEE Transactions on Antennas and Propagation, vol. 66, no. 8, pp. 3877-3885.
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© 1963-2012 IEEE. A dual-linearly polarized, electrically small, low-profile, broadside radiating Huygens dipole antenna is presented, that is, an advanced combination of electric and magnetic near-field resonant parasitic elements. Its prototype was fabricated and tested. The measured results are in good agreement with their simulated values. At 1.515 GHz, the prototype is electrically small ( ka = 0.904 ) and low profile ( 0.0483\lambda -{0} ). It exhibits high port isolation and a large front-to-back ratio (FTBR). The isolation between its two ports is demonstrated to be over 25.8 dB within its -10 dB fractional impedance bandwidth, 0.46%. When port 1 (port 2) is excited, the peak realized gain is 2.03 dBi (2.15 dBi) strictly along the broadside direction with a 12.4 dB (12.1 dB) FTBR.

Tang, MC, Zhou, B, Duan, Y, Chen, X & Ziolkowski, RW 2018, 'Pattern-Reconfigurable, Flexible, Wideband, Directive, Electrically Small Near-Field Resonant Parasitic Antenna', IEEE Transactions on Antennas and Propagation, vol. 66, no. 5, pp. 2271-2280.
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© 1963-2012 IEEE. A pattern-reconfigurable, flexible, wideband, directive, electrically small near-field resonant parasitic (NFRP) antenna is presented. The antenna consists of a pair of Egyptian axe dipole NFRP elements, together with a pair of shaped metallic strips that act as the driven element and are fed by a coaxial cable. These NFRP and driven elements are designed to achieve compactness. Two pairs of p-i-n diodes are integrated into the driven element to enable the pattern reconfigurability. The antenna has two switchable directive endfire states, each pointed in direct opposition to the other. Examples of the evolution of the antenna are used to illustrate its operating principles. A prototype of the optimized design operating in a frequency range centered at 1.8 GHz was fabricated and measured. The simulation and experimental results are in good agreement. The antenna exhibits a wide 13.1% impedance bandwidth and a 4.42 dBi peak realized gain in both pattern-reconfigurable states while maintaining its electrically small size: ka ∼ 0.94. The flexibility of this antenna is demonstrated under different bending conditions by mounting it on cylinders with several different radii, and the results confirm that its performance characteristics are maintained under all of them.

Usman, M, Jan, MA, He, X & Alam, M 2018, 'Performance evaluation of High Definition video streaming over Mobile Ad Hoc Networks', Signal Processing, vol. 148, pp. 303-313.
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© 2018 Video Service Providers (VSPs) can collect and analyze an enormous amount of multimedia data from various cloud storage centers using real-time big data systems for supporting various online customers. The infrastructure-less nature of Mobile Ad Hoc Networks (MANETs) makes the video streaming a challenging task for VSPs. High packet-loss probability in MANETs can create a notable distortion in the received video quality. In this paper, High Definition (HD) videos are streamed over MANETs. First, a transmission model is designed followed by a distortion model to estimate network distortions, such as packet-loss rate and end-to-end delay. Based on the proposed models, a video streaming framework is designed to efficiently utilize the available bandwidth in MANETs, minimize the network distortions, and improve Quality of Service (QoS). Later, an Error Concealment (EC) technique is used to conceal the lost/dropped video frames to improve the Quality of Experience (QoE). Experimental results show that our proposed video streaming framework outperforms the state-of-the-art routing protocols designed for MANETs, such as Destination-Sequenced Distance Vector (DSDV) and Optimized Link Sate Routing (OLSR) protocols. In the end, both subjective and objective evaluations are performed to evaluate the perceptual quality of the concealed video data.

Usman, M, Jan, MA, He, X & Chen, J 2018, 'A Mobile Multimedia Data Collection Scheme for Secured Wireless Multimedia Sensor Networks', IEEE Transactions on Network Science and Engineering.
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IEEE Wireless Multimedia Sensor Networks (WMSNs) produce an enormous amount of big multimedia data. Due to large size, Multimedia Sensor Nodes (MSNs) cannot store generated multimedia data for a long time. In this scenario, mobile sinks can be utilized for data collection. However, due to vulnerable nature of wireless networks, there is a need for an efficient security scheme to authenticate both MSNs and mobile sinks. In this paper, we propose a scheme to protect an underlying WMSN during mobile multimedia data collection. The proposed scheme is a two-layer scheme. At the first layer, all MSNs are distributed into small clusters, where each cluster is represented by a single Cluster Head (CH). At the second layer, all CHs verify identities of mobile sinks before sharing multimedia data. Authentication at both layers ensures a secure data exchange. We evaluate the performance of proposed scheme through extensive simulation results. The simulation results prove that the proposed scheme performs better as compared to existing state-of-the-art approaches in terms of resilience and handshake duration. The proposed scheme is also analyzed in terms of authentication rate, data freshness, and packet delivery ratio, and has shown a better performance.

Usman, M, Yang, N, Jan, MA, He, X, Xu, M & Lam, KM 2018, 'A Joint Framework for QoS and QoE for Video Transmission over Wireless Multimedia Sensor Networks', IEEE Transactions on Mobile Computing, vol. 17, no. 4.
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With the emergence of Wireless Multimedia Sensor Networks (MWSNs), the distribution of multimedia contents have now become a reality. Without proper management, the transmission of multimedia data over WMSNs affects the performance of networks due to excessive packets dropping. The existing studies on Quality of Service (QoS) mostly deal with simple WSNs and as such do not account for an increasing number of sensor nodes and an increasing volume of data. In this paper, we propose a novel framework to support QoS in WMSNs along with a light weight Error Concealment (EC) scheme. The EC schemes play a vital role to enhance Quality of Experience (QoE) by maintaining an acceptable quality at the receiving ends. The main objectives of the proposed framework are to maximise the network throughput and to cover-up the effects produced by dropped video packets. To control the data rate, Scalable Video Coding (SVC) is applied at multimedia sensor nodes with variable Quantization Parameters (QPs). Multipath routing is exploited to support real-time video transmission. Experimental results show that the proposed framework can efficiently adjust large volumes of video data under certain network distortions and can effectively conceal dropped/corrupted video frames by producing better objective measurements.

Van Huynh, N, Hoang, DT, Lu, X, Niyato, D, Wang, P & Kim, DI 2018, 'Ambient Backscatter Communications: A Contemporary Survey', Communications Surveys and Tutorials, IEEE Communications Society, vol. 20, no. 4.
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IEEE Recently, ambient backscatter communications has been introduced as a cutting-edge technology which enables smart devices to communicate by utilizing ambient radio frequency (RF) signals without requiring active RF transmission. This technology is especially effective in addressing communication and energy efficiency problems for low-power communications systems such as sensor networks. It is expected to realize numerous Internet-of-Things (IoT) applications. Therefore, this paper aims to provide a contemporary and comprehensive literature review on fundamentals, applications, challenges, and research efforts/progress of ambient backscatter communications. In particular, we first present fundamentals of backscatter communications and briefly review bistatic backscatter communications systems. Then, the general architecture, advantages, and solutions to address existing issues and limitations of ambient backscatter communications systems are discussed. Additionally, emerging applications of ambient backscatter communications are highlighted. Finally, we outline some open issues and future research directions.

Van Huynh, N, Hoang, DT, Niyato, D, Wang, P & Kim, DI 2018, 'Optimal Time Scheduling for Wireless-Powered Backscatter Communication Networks', IEEE Wireless Communications Letters, vol. 7, no. 5, pp. 820-823.
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© 2012 IEEE. This letter introduces a novel wireless-powered backscatter communication system which allows sensors to utilize RF signals transmitted from a dedicated RF energy source to transmit data. In the proposed system, when the RF energy source transmits RF signals, the sensors are able to backscatter the RF signals to transmit data to the gateway and/or harvest energy from the RF signals for their operations. By integrating backscattering and energy harvesting techniques, we can optimize the network throughput of the system. In particular, we first formulate the time scheduling problem for the system, and then propose an optimal solution using convex optimization to maximize the overall network throughput. Numerical results show a significant throughput gain achieved by our proposed design over two other baseline schemes.

Vo, A, Nguyen, D, Pham, T, Ha, K & Dutkiewicz, E 2018, 'Subject-Independent ERP-based Brain-Computer Interfaces', IEEE Transactions on Neural Systems and Rehabilitation Engineering, vol. 26, no. 4, pp. 719-728.
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Brain–computer interfaces (BCIs) are desirable for people to express their thoughts, especially those with profound disabilities in communication. The classification of brain patterns for each different subject requires an extensively time-consuming learning stage specific to that person, in order to reach satisfactory accuracy performance. The training session could also be infeasible for disabled patients as they may not fully understand the training instructions. In this paper, we propose a unified classification scheme based on ensemble classifier, dynamic stopping, and adaptive learning. We apply this scheme on the P300-based BCI, with the subjectindependent manner, where no learning session is required for new experimental users. According to our theoretical analysis and empirical results, the harmonized integration of these three methods can significantly boost up the average accuracy from 75.00% to 91.26%, while at the same time reduce the average spelling time from 12.62 to 6.78 iterations, approximately to two-fold faster. The experiments were conducted on a large public dataset which had been used in other related studies. Direct comparisons between our work with the others’ are also reported in details.

Wang, N, Li, HW, Ding, C, Shi, LY, Jia, HZ, Ren, ZD & Zhao, ZY 2018, 'A Double-Voltage-Controlled Effective Thermal Conductivity Model of Graphene for Thermoelectric Cooling', IEEE Transactions on Electron Devices, vol. 65, no. 3, pp. 1185-1191.
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© 1963-2012 IEEE. Graphene provides a new opportunity for thermoelectric study based on its unique heat transfer behavior controllable by a gate voltage. In this paper, an effective thermal conductivity model of graphene for thermoelectric cooling is proposed. The model is based on a double-voltage-control mechanism. According to the law of Fourier heat conduction, an effective thermal conductivity model of the proposed thermoelectric cooling device is derived taking a tunable external voltage into account. Then, a gate voltage is used which can change graphene's thermoelectric characteristics. To verify the correctness and effectiveness of the proposed model, a circuit simulation model using HSPICE is built based on the thermoelectric duality. The simulation results from HSPICE and the calculated results from the mathematic model show good agreements with each other. This paper provides a novel precisely controlling method for thermoelectric cooling.

Wang, TQ & Huang, X 2018, 'Fractional Reverse Polarity Optical OFDM for High Speed Dimmable Visible Light Communications', IEEE Transactions on Communications, vol. 66, no. 4, pp. 1565-1578.
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© 1972-2012 IEEE. In this paper, fractional reverse polarity optical orthogonal frequency division multiplexing (FRPO-OFDM) is studied to enable dimming compatible visible light communications. The scheme combines a layered asymmetrically clipped optical OFDM (ACO-OFDM) sequence with an information-carrying brightness control sequence (BCS) in the form of M -ary pulse position modulation. We derive the expressions of the FRPO-OFDM signal and its achievable brightness level, and develop an effective detector which can recover information from both sequences based on maximum likelihood detection. We show that when the detector is to be implemented, the use of multi-layer ACO-OFDM imposes strong periodicity on the BCS, which leads to a trade-off between spectral efficiency and brightness resolution for dimming control. It is shown that high spectral efficiency can be achieved with practical dimming requirements. Simulation results show that the extra information carried by the BCS can be decoded with extremely low bit error rate and thus has negligible impacts on the demodulation of the ACO-OFDM signal, when the system nonlinearity is not dominating.

Wang, TQ, Li, H & Huang, X 2018, 'Interference Cancellation for Layered Asymmetrically Clipped Optical OFDM With Application to Optical Receiver Design', JOURNAL OF LIGHTWAVE TECHNOLOGY, vol. 36, no. 11, pp. 2100-2113.
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Wang, W, Hoang, DT, Niyato, D, Wang, P & Kim, DI 2018, 'Stackelberg game for distributed time scheduling in RF-powered backscatter cognitive radio networks', IEEE Transactions on Wireless Communications, vol. 17, no. 8, pp. 5606-5622.
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© 2002-2012 IEEE. In this paper, we study the transmission strategy adaptation problem in an RF-powered cognitive radio network, in which hybrid secondary users are able to switch between the harvest-then-transmit mode and the ambient backscatter mode for their communication with the secondary gateway. In the network, a monetary incentive is introduced for managing the interference caused by the secondary transmission with imperfect channel sensing. The sensing-pricing-transmitting process of the secondary gateway and the transmitters is modeled as a single-leader-multi-follower Stackelberg game. Furthermore, the follower sub-game among the secondary transmitters is modeled as a generalized Nash equilibrium problem with shared constraints. Based on our theoretical discoveries regarding the properties of equilibria in the follower sub-game and the Stackelberg game, we propose a distributed, iterative strategy searching scheme that guarantees the convergence to the Stackelberg equilibrium. The numerical simulations show that the proposed hybrid transmission scheme always outperforms the schemes with fixed transmission modes. Furthermore, the simulations reveal that the adopted hybrid scheme is able to achieve a higher throughput than the sum of the throughput obtained from the schemes with fixed transmission modes.

Wang, W, Tafti, GF, Ding, M, Luo, Y, Tian, Y, Wang, S, Karpisz, T, Canning, J, Cook, K & Peng, GD 2018, 'Structure formation dynamics in drawing silica photonic crystal fibres', Frontiers of Optoelectronics, vol. 11, no. 1, pp. 69-76.
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© 2018, Higher Education Press and Springer-Verlag GmbH Germany, part of Springer Nature. The special features of photonic crystal fibres (PCFs) are achieved by their air hole structures. PCF structure is determined and formed by its origin preform design and drawing process. Therefore, structure formation dynamics in drawing PCF is important for the fabrication of PCF achieving desirable structure and thus the intended feature. This paper will investigate structure formation dynamics of PCF drawing in relation to key parameters and conditions, such as hole dimension, temperature, pressure, etc.

Wang, Y, Wang, Z, Jia, W, He, X & Jiang, M 2018, 'Joint Learning of Body and Part Representation for Person Re-Identification', IEEE Access, vol. 6, pp. 44199-44210.
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© 2013 IEEE. Person re-identification (ReID), aiming to identify people among multiple camera views, has attracted an increasing attention due to the potential of application in surveillance security. Large variations in subjects' postures, view angles, and illuminating conditions as well as non-ideal human detection significantly increase the difficulty of person ReID. Learning a robust metric for measuring the similarity between different person images is another under-addressed problem. In this paper, following the recent success of part-based models, in order to generate a discriminative and robust feature representation, we first propose to learn global and weighted local body-part features from pedestrian images. Then, in the training phase, angular loss and part-level classification loss are employed jointly as a similarity measure to train the network, which significantly improves the robustness of the resultant network against feature variance. Experimental results on several benchmark data sets demonstrate that our method outperforms the state-of-the-art methods.

Wang, Y, Zhang, J, Liu, Z, Wu, Q, Zhang, Z & Jia, Y 2018, 'Depth Super-Resolution on RGB-D Video Sequences with Large Displacement 3D Motion', IEEE Transactions on Image Processing, vol. 27, no. 7, pp. 3571-3585.
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© 1992-2012 IEEE. To enhance the resolution and accuracy of depth data, some video-based depth super-resolution methods have been proposed, which utilizes its neighboring depth images in the temporal domain. They often consist of two main stages: motion compensation of temporally neighboring depth images and fusion of compensated depth images. However, large displacement 3D motion often leads to compensation error, and the compensation error is further introduced into the fusion. A video-based depth super-resolution method with novel motion compensation and fusion approaches is proposed in this paper. We claim that 3D nearest neighboring field (NNF) is a better choice than using positions with true motion displacement for depth enhancements. To handle large displacement 3D motion, the compensation stage utilized 3D NNF instead of true motion used in the previous methods. Next, the fusion approach is modeled as a regression problem to predict the super-resolution result efficiently for each depth image by using its compensated depth images. A new deep convolutional neural network architecture is designed for fusion, which is able to employ a large amount of video data for learning the complicated regression function. We comprehensively evaluate our method on various RGB-D video sequences to show its superior performance.

Wang, Z & Piccardi, M 2018, 'Minimum-risk temporal alignment of videos', Multimedia Tools and Applications, vol. 77, no. 12, pp. 14891-14906.
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Temporal alignment of videos is an important requirement of tasks such as video comparison, analysis and classification. Most of the approaches proposed to date for video alignment leverage dynamic programming algorithms whose parameters are manually tuned. Conversely, this paper proposes a model that can learn its parameters automatically by minimizing a meaningful loss function over a given training set of videos and alignments. For learning, we exploit the effective framework of structural SVM and we extend it with an original scoring function that suitably scores the alignment of two given videos, and a loss function that quantifies the accuracy of a predicted alignment. The experimental results from four video action datasets show that the proposed model has been able to outperform a baseline and a state-of-the-art algorithm by a large margin in terms of alignment accuracy.

Wong, JKW, Ge, J & He, SX 2018, 'Digitisation in facilities management: A literature review and future research directions', Automation in Construction, vol. 92, pp. 312-326.
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© 2018 Elsevier B.V. Research into digital technology (DT) in construction practices has gained widespread attention. While the application of different DTs in facility management (FM) has been growing, to date, there is no holistic review of the various DT developments and research into FM. A total of 120 academic journal papers, conference proceedings and other technical notes published on the subject, mainly between 2004 and 2017, were reviewed in this paper. The applications of various major DTs, including 1) building information modelling (BIM), 2) reality capture technology (including 3D laser scanning, point cloud), 3) the Internet of Things (IoT) (including radio frequency identification (RFID) and sensor network technologies) and 4) geographic information system (GIS), were reviewed and scrutinised. The review identified a number of possibilities for future research into DT in FM, including, enhancing the interoperability of data, improving the accuracy of point cloud data for developing as-built models for existing facilities, and generating effective BIM/GIS asset database integration. It is hoped that this review and the future directions highlighted in this paper will assist researchers in identifying the areas where further research efforts are most required and in identifying which future directions would be most helpful for digital FM research.

Wong, SW, Zheng, BL, Lin, JY, Zhang, ZC, Yang, Y, Zhu, L & He, Y 2018, 'Design of Three-State Diplexer Using a Planar Triple-Mode Resonator', IEEE Transactions on Microwave Theory and Techniques, vol. 66, no. 9, pp. 4040-4046.
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© 1963-2012 IEEE. A highly integrated three-state diplexer (TSD) on a single planar elliptical structure is for the first time presented in this paper. Three resonant modes are investigated in a planar elliptical resonator, e.g., two TM11 degenerate modes and one TM21 mode. These three resonant modes are designed to form three filtering channels, which are further combined to generate three states of a diplexer, namely, TSD. The planar elliptical triple-mode resonator is fed by three microstrip lines to form a triple-mode TSD. In order to validate the concept, the designed planar TSD is fabricated and measured. The measured results are in good agreement with the simulated ones.

Wu, K, Ni, W, Su, T, Liu, RP & Guo, YJ 2018, 'Fast and Accurate Estimation of Angle-of-Arrival for Satellite-Borne Wideband Communication System', IEEE Journal on Selected Areas in Communications, vol. 36, no. 2, pp. 314-326.
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© 1983-2012 IEEE. Accurate estimation of angle-of-arrival (AoA) is critical to wideband satellite communications, but is susceptible to receive noises and can be ambiguous due to space/cost-effective hybrid antenna array designs with localized analog phased subarrays. As a matter of fact, there has yet to be an unambiguous estimator even for narrow-band systems. This paper proposes a new design of subarray-specific time-varying phase shifts, which enables unambiguous and noise-tolerant estimation of AoA in localized hybrid arrays. Particularly, the new phase shifts deliver deterministic phase changes in the cross-correlations of receive signals between subarrays, and enable the cross-correlations to be coherently accumulated across subarrays and sub-carriers to eliminate ambiguities and tolerate noises. Another important contribution of the paper is that we optimize the frequency interval for coherent accumulation across sub-carriers, leveraging between estimation errors, and accumulation gains. Evident from simulations, our approach is able to dramatically improve the estimation accuracy by orders of magnitudes with significantly reduced requirements of complexities and training symbols, as compared with the state of the art. The approach is robust against noises, with estimation errors asymptotically achieving a rigorously developed lower bound.

Wu, K, Ni, W, Su, T, Liu, RP & Guo, YJ 2018, 'Robust Unambiguous Estimation of Angle-of-Arrival in Hybrid Array With Localized Analog Subarrays', IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS, vol. 17, no. 5, pp. 2987-3002.
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Wu, L, Xu, M, Zhu, G, Wang, J & Rao, T 2018, 'Appearance features in Encoding Color Space for visual surveillance', Neurocomputing, vol. 308, pp. 21-30.
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© 2018 Elsevier B.V. Person re-identification and visual tracking are two important tasks in video surveillance. Many works have been done on appearance modeling for these two tasks. However, existing feature descriptors are mainly constructed on three-channel color spaces, such like RGB, HSV and XYZ. These color spaces somehow enable meaningful representation for color, yet may lack distinctiveness for real-world tasks. In this paper, we propose a multi-channel Encoding Color Space (ECS), and consider the color distinction with the design of image feature descriptor. In order to overcome the illumination variation and shape deformation, we design features on the basis of the Encoding Color Space and Histogram of Oriented Gradient (HOG), which enables rich color-gradient characteristics. Additionally, we extract Second Order Histogram (SOH) on the descriptor constructed to capture abstract information with layout constrains. Exhaustive experiments are performed on datasets VIPeR, CAVIAR, CUHK01 and Visual Tracking Benchmark. Experimental results on these datasets show that our feature descriptors could achieve promising performance.

Xia, H, Zhuge, R, Li, H, Song, S, Jiang, F & Xu, M 2018, 'Single image rain removal via a simplified residual dense network', IEEE Access, vol. 6, pp. 66522-66535.
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© 2013 IEEE. The single-image rain removal problem has attracted tremendous interests within the deep learning domains. Although deep learning based de-raining methods outperform many conventional methods, there are still unresolved issues in regards to improving the performance. In this paper, we propose a simplified residual dense network (SRDN) to improve the de-raining performance and cut down the computation time. Inspired by the image processing domain knowledge that a rainy image can be decomposed into a base (low-pass) layer and a detail (high-pass) layer, we train our network by directly learning the residual between the detail layer of rainy images and the detail layer of clean images. It can both significantly reduce the mapping range from input to output and easily employ the image enhancement operation to handle the heavy rain with hazy looks. Instead of designing a deeper network structure to increase the learning ability of network, we propose a simplified dense block to explore more effective information between layers and, hence, reduce the computation time of network. Experiments on both synthetic and real-world images demonstrate that our SRDN network can achieve competitive results in comparison with the benchmarked and conventional approaches for single-image rain removal.

Xiao, L, Zhang, Y, Zhang, J, Wang, Q & Li, Y 2018, 'Combining HWEBING and HOG-MLBP features for pedestrian detection', The Journal of Engineering, vol. 2018, no. 16, pp. 1421-1426.
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Xie, H, He, Z & Veitch, D 2018, 'Disturbance observer-based visual servoing for multirotor unmanned aerial vehicles', Automatisierungstechnik, vol. 66, no. 3.
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This paper presents a disturbance observer based input saturated visual servoing law for a quadrotor unmanned aerial vehicle (UAV). The controller regulates the 4D relative pose, i. e., 3D translational and yaw motion, between the vehicle and a planar horizontal visual target in an environment with external disturbances. A feedforward control is used to compensate the lumped disturbance consisting of both system uncertainties and external disturbances. The feedback control part is based on a nested saturation control, which is used to bound the orientation of the UAV and therefore helps to keep the visual target in the camera’s field of view. Simulation results are provided to demonstrate controller performance.

Xu, H, Xu, KD, Nie, W & Liu, YH 2018, 'A Coplanar Waveguide Fed UWB Antenna using Embedded E-shaped Structure with WLAN Band-rejection', Frequenz, vol. 72, no. 7-8, pp. 325-332.
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© 2018 Walter de Gruyter GmbH, Berlin/Boston. A compact coplanar waveguide (CPW)-fed ultra-wideband (UWB) monopole antenna using embedded E-shaped structure with wireless local area network (WLAN) band-rejection is presented. The introduction of this E-shaped structure working as the radiator can enhance the impedance bandwidth of the UWB antenna without increasing the overall size. For preventing the interference from WLAN system, a pair of L-shaped stubs are connected to the ground of UWB antenna to create the rejected band. The center frequency of this rejected band is about 5.5 GHz with the rejection range of 5.2∼5.8 GHz. Good agreement can be observed between the simulated and measured results.

Xu, J-X, Zhang, XY, Li, H-Y & Yang, Y 2018, 'Narrowband Single-Pole Double-Throw Filtering Switch Based on Dielectric Resonator', IEEE MICROWAVE AND WIRELESS COMPONENTS LETTERS, vol. 28, no. 7, pp. 594-596.
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Xu, KD, Bai, Y, Zhu, C & Liu, Y 2018, 'Design of filtering power divider with high frequency selectivity', Microwave and Optical Technology Letters, vol. 60, no. 7, pp. 1649-1653.
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© 2018 Wiley Periodicals, Inc. A novel controllable wideband filtering power divider (FPD) with sharp roll-off skirt and good isolation is presented in this article. By introducing a pair of coupled lines and several uniformed quarter-wavelength microstrip lines to the power divider, a wide flat passband with good selectivity is achieved. A resistor is then arranged between the 2 coupled line structures to obtain good isolation. Even-mode and odd-mode approach is applied to deduce the design equations of the proposed FPD. The center frequency can be adjusted flexibly by simply controlling the length of the coupled lines and the other microstrip lines. Eventually, the proposed power divider centered at 2.3 GHz with a fractional bandwidth of 75% is fabricated and measured for verification. The measured minimum in-band insertion loss is 0.3 dB, while the isolation is better than 20 dB. Good agreement is shown between the simulated and measured results.

Xu, KD, Li, D, Liu, Y & Liu, QH 2018, 'Printed Quasi-Yagi Antennas Using Double Dipoles and Stub-Loaded Technique for Multi-Band and Broadband Applications', IEEE Access, vol. 6, pp. 31695-31702.
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© 2013 IEEE. Double dipoles on a single-layer substrate are utilized to construct a triple-mode printed quasi-Yagi antenna for the multi-band and broadband antenna applications. A stub-loaded dipole generating two resonant modes (i.e., lower dual-mode dipole) is allocated on the underside of a simple dipole (i.e., upper single-mode dipole) introducing the third resonant mode. Using these three resonant modes, three compact printed quasi-Yagi antennas, i.e., tri-band, dual-band, and broadband printed quasi-Yagi antennas, are designed with the same antenna prototype but different parameter values. Seen from the measured results, all of these three antennas have good unidirectional radiations, high radiation efficiencies, and low cross-polarization levels at the operating frequencies within the impedance bandwidths.

Xu, KD, Li, M, Liu, Y, Yang, Y & Liu, QH 2018, 'Design of Triplexer Using E-Stub-Loaded Composite Right-/Left-Handed Resonators and Quasi-Lumped Impedance Matching Network', IEEE ACCESS, vol. 6, pp. 18814-18821.
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Xu, KD, Luo, Z, Liu, Y & Liu, QH 2018, 'High-selectivity single-ended and balanced bandpass filters using ring resonators and coupled lines loaded with multiple stubs', AEU - International Journal of Electronics and Communications, vol. 96, pp. 193-198.
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© 2018 Elsevier GmbH High-selectivity single-ended and balanced bandpass filters (BPFs) using dual-mode ring resonators and coupled lines loaded with multiple stubs are proposed in this paper. With the help of the loaded short-circuited and open-circuited stubs, six deep transmission zeros (TZs) from 0 to 2f 0 (f 0 : center frequency of the passband) can be realized in both of single-ended and balanced BPFs to improve the stopband suppressions. The functions of the loaded short/open stubs and calculated analysis of TZs’ positions have been presented. For further demonstration, two examples of single-ended BPF and balanced BPF with high common-mode suppression are designed and fabricated, whose center frequencies are both at 2.1 GHz. Their measured 3-dB fractional bandwidths are 23.7% and 24.7% (differential-mode), respectively. The simulated results and measurements of these two filters are in good agreement.

Xu, KD, Xu, H, Liu, Y, Li, J & Liu, QH 2018, 'Microstrip Patch Antennas with Multiple Parasitic Patches and Shorting Vias for Bandwidth Enhancement', IEEE Access, vol. 6, pp. 11624-11633.
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© 2013 IEEE. Two novel microstrip patch antennas with multiple parasitic patches and shorting vias have been presented for the bandwidth enhancement. Based on the conventional triangular patch antenna, two more resonances can be obtained with the introduction of multiple parasitic patches, and consequently, the antenna bandwidth can be broadened. Parametric analysis of the patches has been studied for the verification of bandwidth enhancement. An example of the proposed antenna with multiple parasitic patches is designed, fabricated, and tested. The measured bandwidth with vert S11}vert < -10 dB ranges from 5.46 to 6.27 GHz (13.8%), and good far-field radiation patterns can be obtained within the frequency band. In addition, two shorting vias are inserted into the above proposed antenna to decrease the input impedance, resulting in further bandwidth enhancement of the antenna. This antenna is fabricated and tested as well, which achieves a measured 10-dB impedance bandwidth of 17.4% from 5.5 to 6.55 GHz.

Xu, KD, Zhang, F, Liu, Y & Liu, QH 2018, 'Bandpass Filter Using Three Pairs of Coupled Lines with Multiple Transmission Zeros', IEEE Microwave and Wireless Components Letters, vol. 28, no. 7, pp. 576-578.
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© 2001-2012 IEEE. A novel but very simple bandpass filter using just three pairs of coupled lines with multiple transmission zeros (TZs) and transmission poles is proposed in this letter. The filter structure can be seen as the two one-wavelength ring resonators coupled each other with \lambda -{g}/4 coupled length and sandwiched between the 3\lambda -{g}/4 input and output feedlines. Good out-of-band suppression and sharp roll-off skirts can be realized by multiple fixed and tunable TZs without complicated coupling scheme. For further demonstration, a filter example with center frequency at f-{0}= 2.1 GHz is implemented with generation of eight TZs at the frequency range from 0 to 2f-{0} for theoretically calculated certification. Good agreement between simulation and measured results validates the design method.

Xu, KD, Zhang, F, Liu, Y & Nie, W 2018, 'High selectivity seventh-order wideband bandpass filter using coupled lines and open/shorted stubs', Electronics Letters, vol. 54, no. 4, pp. 223-225.
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© The Institution of Engineering and Technology 2018 A compact seventh-order wideband bandpass filter (BPF) with sharp roll-off skirts using coupled lines and open stubs (OSs)/shorted stubs (SSs) is proposed. Seven transmission poles in the passband and four deep transmission zeros from 0 to 2f0 (f0 denotes centre frequency of the passband) can be realised with the help of half-wavelength OSs and quarter-wavelength SSs. For demonstration, a wideband BPF prototype is designed, fabricated with a measured 3-dB fractional bandwidth of 78% (1.22–2.77 GHz) and transition band roll-off rates of over 175 dB/GHz. Good agreement between the simulations and measurements validates the design method.

Yan, B, Zhao, Q, Wang, Z & Zhang, J 2018, 'Adaptive decomposition-based evolutionary approach for multiobjective sparse reconstruction', Information Sciences, vol. 462, pp. 141-159.
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© 2018 Elsevier Inc. This paper aims at solving the sparse reconstruction (SR) problem via a multiobjective evolutionary algorithm. Existing multiobjective evolutionary algorithms for the SR problem have high computational complexity, especially in high-dimensional reconstruction scenarios. Furthermore, these algorithms focus on estimating the whole Pareto front rather than the knee region, thus leading to limited diversity of solutions in knee region and waste of computational effort. To tackle these issues, this paper proposes an adaptive decomposition-based evolutionary approach (ADEA) for the SR problem. Firstly, we employ the decomposition-based evolutionary paradigm to guarantee a high computational efficiency and diversity of solutions in the whole objective space. Then, we propose a two-stage iterative soft-thresholding (IST)-based local search operator to improve the convergence. Finally, we develop an adaptive decomposition-based environmental selection strategy, by which the decomposition in the knee region can be adjusted dynamically. This strategy enables to focus the selection effort on the knee region and achieves low computational complexity. Experimental results on simulated signals, benchmark signals and images demonstrate the superiority of ADEA in terms of reconstruction accuracy and computational efficiency, compared to five state-of-the-art algorithms.

Yang, L, Liu, Y, Zhu, C, Liu, L & Liu, QH 2018, 'Synthesis of frequency-invariant patterns by the fast multitask compressive sensing', IEEJ Transactions on Electrical and Electronic Engineering, vol. 13, no. 1, pp. 175-176.
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© 2017 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. A new method for the synthesis of wideband frequency-invariant pencil-beam patterns with nonuniformly spaced linear arrays is proposed. This scheme is designed under the framework of fast multitask compressive sensing. The minimum spacing between antenna elements can be controlled to make sure that the obtained arrays are physically realizable. The results achieved are comparable to those obtained by the state-of-the-art techniques. © 2017 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

Yang, N, Fan, X, Puthal, D, He, X, Nanda, P & Guo, S 2018, 'A Novel Collaborative Task Offloading Scheme for Secure and Sustainable Mobile Cloudlet Networks', IEEE Access, vol. 6.
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OAPA With the advancement of wireless networking technologies and communication infrastructures, mobile cloud computing has emerged as a pervasive paradigm to execute computing tasks for capacity-limited mobile devices. More specifically, at the network edge, the resource-rich and trusted cloudlet system can provide in-proximity computing services by executing the workloads for nearby devices. Nevertheless, there are chances for malicious users to generate DDoS (Distributed Denial-of-Service) flooding tasks to overwhelm cloudlet servers and block computing services from legitimate users. Load balancing is one of the most effective methods to solve DDoS attacks in distributed networks. However, existing solutions require overall load information to achieve load balancing in cloudlet networks, making it costly in both communication and computation. To achieve more efficient and low-cost load balancing, we propose CTOM, a novel Collaborative Task Offloading scheMe to avoid DDoS attacks for secure and sustainable mobile cloudlet networks. The proposed solution is based on the balls-and-bins theory and it can balance the task loads with extremely limited information. The CTOM reduces the number of overloaded cloudlets smoothly, thus handling the potential DDoS attacks in mobile cloudlet networks. Extensive simulations and evaluation demonstrate that, the proposed CTOM outperforms the conventional random and proportional allocation schemes in reducing the task gaps between maximum load and minimum load among mobile cloudlets by 65% and 55%, respectively.

Yang, T, Ding, C, Ziolkowski, RW & Guo, YJ 2018, 'Circular hole ENZ photonic crystal fibers exhibit high birefringence.', Optics express, vol. 26, no. 13, pp. 17264-17278.
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-A novel photonic crystal fiber (PCF) design that yields very high birefringence is proposed and analyzed. Its significantly enhanced birefringence is achieved by filling selected air holes in the cladding with an epsilon-near-zero (ENZ) material. Extensive simulation results of this asymmetric material distribution in the lower THz range demonstrate that the reported PCF has a birefringence above 0.1 and a loss below 0.01 cm-1 over a wide band of frequencies. Moreover, it exhibits near zero dispersion at 0.75 THz for both the X- and Y-polarization modes and a birefringence equal to 0.28. This THz PCF is then scaled successfully to optical frequencies. While the high birefringence is maintained, this optical PCF has a very high loss in its Y-polarization mode and, consequently, yields single-polarization single-mode (SPSM) propagation, exhibiting near zero dispersion at the optical telecom wavelength of 1.55 μm. The ideal ENZ materials used for these conceptual models are replaced with realistic ones for both the THz and optical PCF designs. With the currently available ENZ materials, the realistic PCFs still have a high birefringence, but with higher losses compared to the idealized results. Future developments of ENZ materials that achieve lower loss properties will mitigate this issue in any frequency band of high interest.

Yang, T, Ding, C, Ziolkowski, RW & Jay Guo, Y 2018, 'A Scalable THz Photonic Crystal Fiber with Partially-Slotted Core That Exhibits Improved Birefringence and Reduced Loss', Journal of Lightwave Technology, vol. 36, no. 16, pp. 3408-3417.
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© 1983-2012 IEEE. A photonic crystal fiber (PCF) based on high resistivity silicon is reported that exhibits high birefringence, low loss, and flat dispersion characteristics across a wide bandwidth in the THz regime. Except for the center region, which remains the background dielectric, its core is occupied by a set of rectangular air slots. The material and configuration lead to high birefringence and low loss. The simulation results, which include the material losses, indicate that a birefringence value of 0.82 and a total loss of 0.011 cm-1, including the effective material loss and confinement losses, are achieved at 1.0 THz. These values are a factor of ten times higher and four times lower, respectively, than many recent designs. The numerical analyses also demonstrate that the reported PCF can be scaled to any desired portion of the THz regime, while maintaining a similar birefringence, simply by changing the lattice constant. This 'scalable' characteristic is shown to be applicable to other PCF designs. It could facilitate a novel way of testing THz fibers, i.e., it suggests that one only needs to test the preform to validate the performance of the fiber at higher frequencies. This outcome would significantly reduce the design complexity and the costs of PCF testing.

Yang, W, Li, J, Zheng, H & Xu, RYD 2018, 'A Nuclear Norm Based Matrix Regression Based Projections Method for Feature Extraction', IEEE Access, vol. 6, pp. 7445-7451.
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© 2013 IEEE. In the traditional graph embedding framework, the graph is usually built by k-NN or r-ball. Since it is difficult to manually set the parameters k and r in the high-dimensional space, sparse representation-based methods are usually introduced to automatically build the graphs. In recent years, nuclear norm-based matrix regression (NMR) has been proposed for face recognition using the low rank structural information (i.e., the image matrix-based error model). Inspired by NMR, we give a NMR-based projections (NMRP) method for feature extraction and recognition. The experiments on FERET and extended Yale B face databases show that NMR can be used to build the graph while NMRP is an effective feature extraction method.

Yang, X, Qin, PY, Liu, Y, Yin, YZ & Guo, YJ 2018, 'Analysis and Design of a Broadband Multifeed Tightly Coupled Patch Array Antenna', IEEE Antennas and Wireless Propagation Letters, vol. 17, no. 2, pp. 217-220.
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© 2017 IEEE. In this letter, a multifeed tightly coupled patch array antenna capable of broadband operation is analyzed and designed. First, an antenna array composed of infinite elements with each element excited by a feed is proposed. To produce specific polarized radiation efficiently, a new patch element is proposed, and its characteristics are studied based on a 2-port network model. Full-wave simulation results show that the infinite antenna array exhibits both a high efficiency and desirable radiation pattern in a wide frequency band (10 dB bandwidth) from 1.91 to 5.35 GHz (94.8%). Second, to validate its outstanding performance, a realistic finite 4 × 4 antenna prototype is designed, fabricated, and measured in our laboratory. The experimental results agree well with simulated o nes, where the frequency bandwidth (VSWR < 2) is from 2.5 to 3.8 GHz (41.3%). The inherent compact size, light weight, broad bandwidth, and good radiation characteristics make this array antenna a promising candidate for future communication and advanced sensing systems.

Yang, Y & Zhu, X 2018, 'A Wideband Reconfigurable Antenna with 360° Beam Steering for 802.11ac WLAN Applications', IEEE Transactions on Antennas and Propagation, vol. 66, no. 2, pp. 600-608.
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© 1963-2012 IEEE. A novel 360° beam steering patch antenna with parasitic elements is presented in this paper. The designed antenna consists of a radiating patch and six parasitic elements, each of which is connected through a group of shorting vias controlled by p-i-n diode switches. By switching on the desired groups of the shorting vias, the electric field distribution inside substrate cavity appears at the desired beam direction. Rotationally switching on the groups of the shorting vias, the performance of 360° beam scanning is realized. To further understand operating mechanism, the antenna is modeled with equivalent circuit in terms of the on and off status of a sector of the antenna, which can be used as a design guide for shorting-vias-controlled reconfigurable microstrip patch antennas. The fabricated antenna achieves a bandwidth of 14.5%, a peak gain of 10 dBi, and the efficiency of 80.5%. The achieved beamwidths are 42° and 97° in azimuth and elevation planes, respectively. With an ability of being steered around zenith axis at six directions, the scanned beam range covers the entire 360°. The physical dimension is only 2.5 λ g for the size and 0.5λ g for the profile. This antenna operates from 5.1 to 5.9 GHz and has significant meaning in the IEEE 802.11ac wireless local area network applications due to its capabilities of generating 360° steered beams.

Yang, Y, Li, Z, Wang, S, Chen, X, Wang, J & Guo, YJ 2018, 'Miniaturized High-Order-Mode Dipole Antennas Based on Spoof Surface Plasmon Polaritons', IEEE Antennas and Wireless Propagation Letters, vol. 17, no. 12, pp. 2409-2413.
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© 2002-2011 IEEE. A miniaturization method for antennas is developed based on spoof surface plasmon polaritons (SSPPs). With a large phase constant on the SSPPs transmission line, the guide wavelength can be dramatically reduced, with great potential on the miniaturization application of antennas. By introducing a miniaturization factor M, the relationship between M and the phase constant on the SSPPs dipole is studied, providing guidance to the design of miniaturized SSPPs dipoles. Then, SSPPs dipoles operating at 2.4 GHz are designed, including both the odd-And even-resonance dipoles. Simple feeding structures are developed for the odd-And even-resonance dipoles, respectively, and particularly for the even-resonance mode to realize a transition from 50 Ω to very large input impedance of the dipole. The miniaturized SSPPs dipoles operating at the 1st, 2nd, 3rd, and 4th modes are fabricated. The measured reflection coefficients and radiation patterns show good agreements with the simulated results. It can be concluded that the dipole lengths for these modes are reduced by 8%, 11%, 10%, and 13%, respectively, compared with the conventional printed dipoles on the same substrate.

Yang, Y, Zhu, H, Zhu, X & Xue, Q 2018, 'A Low-Loss Bandpass Filter using Edge-Coupled Resonator with Capacitive Feeding in (Bi)-CMOS Technology', IEEE Electron Device Letters, vol. 39, no. 6, pp. 787-790.
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© 1980-2012 IEEE. In this Letter, a flexible approach for low-loss on-chip bandpass filter (BPF) design in CMOS technology is presented. The proposed approach takes the advantages of a combination of an edge-coupled electromagnetic structure, namely resonator, and a pair of metal-insulator-metal capacitors for BPF implementation. To demonstrate the insight of the approach, the designed resonator is analyzed in details by means of a simplified equivalent LC-circuit model. Then, the impact on the BPF design due to the variations of the feeding capacitance is investigated. To prove the concept, both the resonator and BPF are fabricated in a standard 0.13- μ m CMOS technology. The measured results show that the designed resonator can generate a notch with 20-dB attenuation at 59.4 GHz, while the BPF has a center frequency of 35.4 GHz with an insertion loss of 1.7 dB. The chip size of both devices, excluding the test pads, is only 0.039 mm2(0.15 × 0.26 mm2).

Yang, Y, Zhu, X & Xue, Q 2018, 'Design of an Ultracompact On-Chip Bandpass Filter Using Mutual Coupling Technique', IEEE Transactions on Electron Devices, vol. 65, no. 3, pp. 1087-1093.
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© 1963-2012 IEEE. In this paper, design of an ultracompact bandpass filter (BPF) in GaAs technology without compromising its electrical performance is investigated by means of both theoretical analysis and electromagnetic simulation. In particular, the relationship between the external quality factor and the coupling coefficient of the second-order BPF is formulized to better understand the principle of the mutual coupling effect. To prove the concept, the designed filter is implemented in a commercial 0.1-μm GaAs technology. A step-by-step design guideline is elaborated. The BPF has not only the merits of ultracompactness, but also remarkable insertion loss (IL) compared with other state-of-The-Art on-chip designs. The measurement results show that the 1-dB bandwidth of the BPF is from 28 to 36 GHz, while the IL is less than 1 dB at 29.5 GHz. In addition, more than 40-dB rejection is achieved from 56 to 69 GHz. The size of the filter is only 230 × 280 μm2, excluding the pads, which is equivalent to 0.074 × 0.09 λg μm2} at 28 GHz. To the best of our knowledge, the proposed design is known to be the most compact one in the open literature using GaAs technologies.

Ye, L, Sui, K, Liu, Y, Zhang, M & Huo Liu, Q 2018, 'Graphene-based hybrid plasmonic waveguide for highly efficient broadband mid-infrared propagation and modulation', Optics Express, vol. 26, no. 12, pp. 15935-15947.
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© 2018 Optical Society of America. In this paper, a graphene-based hybrid plasmonic waveguide is proposed for highly efficient broadband surface plasmon polariton (SPP) propagation and modulation at mid-infrared (mid-IR) spectrum. The hybrid plasmonic waveguide is composed of a monolayer graphene sheet in the center, a polysilicon gating layer, and two inner dielectric buffer layers and two outer parabolic-ridged silicon substrates symmetrically placed on both sides of the graphene. Owing to the unique parabolic-ridged waveguide structure, the light-graphene interaction and subwavelength SPPs confinement of the fundamental SPP mode for the hybrid waveguide can be significantly increased. Under the graphene chemical potential of 1.0 eV, the proposed waveguide can achieve outstanding SPP propagation performance with long propagation length of 12.1-16.7 μm and small normalized mode area of ~10 −4 in the frequency range of 10-20 THz, exhibiting more than one order smaller in the normalized mode area while remaining the propagation length almost the same level with respect to the hybrid plasmonic waveguide without parabolic ridges. By tuning the graphene chemical potential from 0.1 to 1.0 eV, we demonstrate the waveguide has a modulation depth greater than 51% for the frequency ranging from 10 to 20 THz and reaches a maximum of nearly 100% at the frequency higher than 18 THz. Benefitting from the excellent broadband mid-IR propagation and modulation performance, the graphene-based hybrid plasmonic waveguide may open up a new way for various mid-IR waveguides, modulators, interconnects and optoelectronic devices.

Yuan, W, Wu, N, Yan, C, Li, Y, Huang, X & Hanzo, L 2018, 'A low-complexity energy-minimization-based SCMA detector and its convergence analysis', IEEE Transactions on Vehicular Technology, vol. 67, no. 12, pp. 12398-12403.
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© 2018 IEEE. Sparse code multiple access (SCMA) has emerged as a promising non-orthogonal multiple access technique for the next-generation wireless communication systems. Since the signal of multiple users is mapped to the same resources in SCMA, its detection imposes a higher complexity than that of the orthogonal schemes, where each resource slot is dedicated to a single user. In this paper, we propose a low-complexity receiver for SCMA systems based on the radical variational free energy framework. By exploiting the pairwise structure of the likelihood function, the Bethe approximation is utilized for estimating the data symbols. The complexity of the proposed algorithm only increases linearly with the number of users, which is much lower than that of the maximum a posteriori detector associated with exponentially increased complexity. Furthermore, the convergence of the proposed algorithm is analyzed, and its convergence conditions are derived. Simulation results demonstrate that the proposed receiver is capable of approaching the error probability performance of the conventional message-passing-based receiver.

Yuan, X, Feng, Z, Xu, W, Ni, W, Zhang, JA, Wei, Z & Liu, RP 2018, 'Capacity Analysis of UAV Communications: Cases of Random Trajectories', IEEE Transactions on Vehicular Technology, vol. 67, no. 8, pp. 7564-7576.
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© 1967-2012 IEEE. This paper analyzes the link capacity between autonomous unmanned aerial vehicles (UAVs) with random three-dimensional (3-D) trajectories. This is distinctively different from existing works typically under the assumption of either two-dimensional (2-D) or deterministic trajectories, and particularly interesting to applications such as surveillance and air combat. The key idea is that we geometrically derive the probability distributions of the UAV-to-UAV (U2U) distances which, by exploiting the Jensen's inequality, can be translated to the closed-form bounds for the capacity between UAVs, and between UAVs and ground stations. Another important aspect is that we extrapolate the idea to dense UAV networks, and analyze the impact of network densification, imperfect channel state information, and interference from ground transmitters on the capacity. Corroborated by simulations, our analysis shows that a U2U link with random 2-D trajectories is superior in terms of capacity due to its short average link distance. It is also revealed that a UAV-to-ground link can incur substantially lower capacity than a U2U link even in the case the 3-D coverage of the UAVs is the same, as the result of its longer average link length.

Yuan, X, Feng, Z, Xu, W, Wei, Z & Liu, R 2018, 'Secure Connectivity Analysis in Unmanned Aerial Vehicle Networks', Frontiers of Information Technology and Electronic Engineering, vol. 19, no. 3, pp. 409-422.
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The distinctive characteristics of unmanned aerial vehicle networks (UAVNs), including highly dynamic network topology, high mobility, and open-air wireless environments, may make UAVNs vulnerable to attacks and threats. In this study, we propose a novel trust model for UAVNs that is based on the behavior and mobility pattern of UAV nodes and the characteristics of inter-UAV channels. The proposed trust model consists of four parts: direct trust section, indirect trust section, integrated trust section, and trust update section. Based on the trust model, the concept of a secure link in UAVNs is formulated that exists only when there is both a physical link and a trust link between two UAVs. Moreover, the metrics of both the physical connectivity probability and the secure connectivity probability between two UAVs are adopted to analyze the connectivity of UAVNs. We derive accurate and analytical expressions of both the physical connectivity probability and the secure connectivity probability using stochastic geometry with or without Doppler shift. Extensive simulations show that compared with the physical connection probability with or without malicious attacks, the proposed trust model can guarantee secure communication and reliable connectivity between UAVs and enhance network performance when UAVNs face malicious attacks and other security risks.

Zeng, J, Lv, T, Liu, RP, Su, X, Peng, M, Wang, C & Mei, J 2018, 'Investigation on Evolving Single-Carrier NOMA into Multi-Carrier NOMA in 5G', IEEE Access, vol. 6, pp. 48268-48288.
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© 2013 IEEE. Non-orthogonal multiple access (NOMA) is one promising technology, which provides high system capacity, low latency, and massive connectivity, to address several challenges in the fifth-generation wireless systems. In this paper, we first reveal that the NOMA techniques have evolved from single-carrier NOMA (SC-NOMA) into multi-carrier NOMA (MC-NOMA). Then, we comprehensively investigated on the basic principles, enabling schemes and evaluations of the two most promising MC-NOMA techniques, namely sparse code multiple access (SCMA) and pattern division multiple access (PDMA). Meanwhile, we consider that the research challenges of SCMA and PDMA might be addressed with the stimulation of the advanced and matured progress in SC-NOMA. Finally, yet importantly, we investigate the emerging applications, and point out the future research trends of the MC-NOMA techniques, which could be straightforwardly inspired by the various deployments of SC-NOMA.

Zeng, J, Peng, J, Liu, RP & Su, X 2018, 'Comments on "Cross-Tier Cooperation for Optimal Resource Utilization in Ultra-Dense Heterogeneous Networks"', IEEE Transactions on Vehicular Technology, vol. 67, no. 11, pp. 11307-11308.
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© 2018 IEEE. Two adaptive dedicated channel allocation algorithms, namely dynamic dedicated channel partitioning (D2CP) and dynamic dedicated channel partitioning with cooperation (D2CP-C), were proposed in [1] to improve the system throughput of ultra-dense networks (UDN). However, due to the incorrect use of the geometric-arithmetic mean inequality theorem, the average system throughput could not be guaranteed to be optimal. In this letter, we study the proposed D2CP and D2CP-C algorithms in UDN and deduce the average system throughput. Consequently, we prove that the equal resource allocation strategy proposed in [1] is strictly not optimal.

Zha, X, Ni, W, Wang, X, Liu, RP, Guo, YJ, Niu, X & Zheng, K 2018, 'The impact of link duration on the integrity of distributed mobile networks', IEEE Transactions on Information Forensics and Security, vol. 13, no. 9, pp. 2240-2255.
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© 2005-2012 IEEE. A major challenge in distributed mobile networks is network integrity, resulting from short link duration and severe transmission collisions. This paper analyzes the impact of link duration and transmission collisions on a range of on-the-fly authentication protocols, which operate based on predistributed keys and can instantly verify and forward messages. All unexpired messages within a link duration can be verified retrospectively, once the keys are matched on-the-air. We develop a new general 4D Markov model which, apart from the first three dimensions modeling a cycle of the protocols, is able to unprecedentedly capture unexpired messages between cycles in the fourth dimension. Validated by simulation, our analysis reveals that the on-the-fly authentication is efficient under short link duration, but is susceptible to transmission collisions. The authentication requires holistic cross-layer designs of retransmission and rekeying. The proposed model is able to facilitate the design of the protocol parameters, which allows the protocols to significantly outperform the state of the art.

Zhang, G, Piccardi, M & Zare Borzeshi, E 2018, 'Sequential Labeling With Structural SVM Under Nondecomposable Losses', IEEE Transactions on Neural Networks and Learning Systems, pp. 4177-4188.
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IEEE Sequential labeling addresses the classification of sequential data, which are widespread in fields as diverse as computer vision, finance, and genomics. The model traditionally used for sequential labeling is the hidden Markov model (HMM), where the sequence of class labels to be predicted is encoded as a Markov chain. In recent years, HMMs have benefited from minimum-loss training approaches, such as the structural support vector machine (SSVM), which, in many cases, has reported higher classification accuracy. However, the loss functions available for training are restricted to decomposable cases, such as the 0-1 loss and the Hamming loss. In many practical cases, other loss functions, such as those based on the F & #x2081; measure, the precision/recall break-even point, and the average precision (AP), can describe desirable performance more effectively. For this reason, in this paper, we propose a training algorithm for SSVM that can minimize any loss based on the classification contingency table, and we present a training algorithm that minimizes an AP loss. Experimental results over a set of diverse and challenging data sets (TUM Kitchen, CMU Multimodal Activity, and Ozone Level Detection) show that the proposed training algorithms achieve significant improvements of the F & #x2081; measure and AP compared with the conventional SSVM, and their performance is in line with or above that of other state-of-the-art sequential labeling approaches.

Zhang, H & Xu, M 2018, 'Recognition of Emotions in User-Generated Videos with Kernelized Features', IEEE Transactions on Multimedia, vol. 20, no. 10, pp. 2824-2835.
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© 1999-2012 IEEE. Recognition of emotions in user-generated videos has attracted increasing research attention. Most existing approaches are based on spatial features extracted from video frames. However, due to the broad affective gap between spatial features of images and high-level emotions, the performance of existing approaches is restricted. To bridge the affective gap, we propose recognizing emotions in user-generated videos with kernelized features. We reformulate the equation of the discrete Fourier transform as a linear kernel function and construct a polynomial kernel function based on the linear kernel. The polynomial kernel is applied to spatial features of video frames to generate kernelized features. Compared with spatial features, kernelized features show superior discriminative capability. Moreover, we are the first to apply the sparse representation method to reduce the impact of noise contained in videos; this method helps contribute to performance improvement. Extensive experiments are conducted on two challenging benchmark datasets, that is, VideoEmotion-8 and Ekman-6. The experimental results demonstrate that the proposed method achieves state-of-the-art performance.

Zhang, J, Wu, Q, Shen, C, Zhang, J & Lu, J 2018, 'Multilabel Image Classification with Regional Latent Semantic Dependencies', IEEE Transactions on Multimedia, vol. 20, no. 10, pp. 2801-2813.
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© 1999-2012 IEEE. Deep convolution neural networks (CNNs) have demonstrated advanced performance on single-label image classification, and various progress also has been made to apply CNN methods on multilabel image classification, which requires annotating objects, attributes, scene categories, etc., in a single shot. Recent state-of-the-art approaches to the multilabel image classification exploit the label dependencies in an image, at the global level, largely improving the labeling capacity. However, predicting small objects and visual concepts is still challenging due to the limited discrimination of the global visual features. In this paper, we propose a regional latent semantic dependencies model (RLSD) to address this problem. The utilized model includes a fully convolutional localization architecture to localize the regions that may contain multiple highly dependent labels. The localized regions are further sent to the recurrent neural networks to characterize the latent semantic dependencies at the regional level. Experimental results on several benchmark datasets show that our proposed model achieves the best performance compared to the state-of-the-art models, especially for predicting small objects occurring in the images. Also, we set up an upper bound model (RLSD+ft-RPN) using bounding-box coordinates during training, and the experimental results also show that our RLSD can approach the upper bound without using the bounding-box annotations, which is more realistic in the real world.

Zhang, J, Zareapoor, M, He, X, Shen, D, Feng, D & Yang, J 2018, 'Mutual information based multi-modal remote sensing image registration using adaptive feature weight', Remote Sensing Letters, vol. 9, no. 7, pp. 646-655.
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Multi-module images registration is a challenging task in image processing, and more especially in the field of remote sensing. In this letter, we strive to present a novel mutual information scheme for image registration in remote sensing scenario based on feature map technique. We firstly take saliency detection advantages to extract geographic pattern, and then utilize the efficient Laplacian of Gaussian(LOG) and Guided Filter methods to construct a new feature map based on different characteristic of multi-channel images. To avoid practical traps of sub-optimization, we propose an novel mutual information(MI) algorithm based on an adapted weight strategy. The proposed model divides an image into patches and assigns weighted values according to patch similarities in order to solve the optimization problem, improve accuracy and enhance performance. Note that, our proposed method incorporates the LOG and Guided Filter methods into image registration for the first time to construct a new feature map based on differences and similarities strategy. Experiments are conducted over island and coastline scenes, and reveal that our hybrid model has a significant performance and outperforms the state-of-the-art methods in remote sensing image registration

Zhang, JA, Chen, Z, Cheng, P & Huang, X 2018, 'Sub-optimal Implementation of Sparse Bayesian Learning with Reduced Complexity', Signal Processing, pp. 153-158.
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Zhang, T, Bao, J, Cai, Z, Yang, Y, Zhu, H, Zhu, X & Dutkiewicz, E 2018, 'A C-Band Compact Wideband Bandpass Filter with High Selectivity and Improved Return Loss', IEEE Microwave and Wireless Components Letters, vol. 28, no. 9, pp. 777-779.
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© 2001-2012 IEEE. In this letter, a C-band compact wideband bandpass filter (BPF) with high selectivity and improved return loss (RL) is proposed. Two pairs of short-circuited stubs are employed on a transmission-line model to generate three transmission poles and two transmission zeros (TZs), where the odd-and even-mode analysis is used to analyze the resonant frequencies of the BPF. By applying the transversal signal-interference technique, two additional TZs can be generated in the upper and lower stopbands, respectively. The measured results show that the 3-dB fractional bandwidth is 62.8% at the center frequency of 5 GHz. The RL and the insertion loss within the passband are better than 22 and 0.6 dB, respectively. Moreover, the roll-off rate is up to 100 dB/GHz.

Zhang, T, Gao, X, Du, J & Guo, YJ 2018, 'Full em Design Method for HTS MMIC Josephson Mixers', IEEE Transactions on Applied Superconductivity, vol. 28, no. 4.
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© 2002-2011 IEEE. We report the full electromagnetic (EM) design and simulation method, and applied it to develop a 34-GHz high-temperature superconducting (HTS) microwave monolithic integrated circuit Josephson mixer. The mixer is modeled in EM simulation software, high-frequency simulation structural simulator, with the junction area modeled as an excitation port with frequency-dependent impedance. Impedance matching between the junction and RF/IF ports is then optimized accordingly. Module design is carried out for the optimized HTS Josephson mixer, and the cavity resonance issue is investigated and eliminated. The HTS mixer module was experimentally developed and measured to verify the simulation. The measured frequency response of the conversion gain agrees with the simulation results of combined RF and IF transmission loss.

Zhang, T, Jia, W, Gong, C, Sun, J & Song, X 2018, 'Semi-supervised dictionary learning via local sparse constraints for violence detection', Pattern Recognition Letters, vol. 107, pp. 98-104.
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© 2017 Elsevier B.V. In this paper, we propose a novel semi-supervised learning framework for violence detection in video surveillance. With this framework, a classifier which distinguishes violent behavior from normal behavior can be trained using inexpensive unlabeled data with the assistance of human operators. Our approach can learn a single dictionary and a predictive linear classifier jointly. Specifically, we integrate the reconstruction error of labeled and unlabeled data, representation constraints and the coefficient incoherence into an objective function for dictionary learning, which enhances the representative and discriminative power of the established dictionary. This has contributed to that the dictionary and the classifier learned from the labeled set yield very small generalization error on unseen data. Experimental results on benchmark datasets have demonstrated the effectiveness of our approach in violence detection.

Zhang, T, Li, J, Jia, W, Sun, J & Yang, H 2018, 'Fast and robust occluded face detection in ATM surveillance', Pattern Recognition Letters, vol. 107, pp. 33-40.
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© 2017 Elsevier B.V. Crimes with respect to ATMs (Automatic Teller Machines) have attracted more and more attention, where criminals deliberately cover their faces in order to avoid being identified. This paper proposes a fast and robust face occlusion detection algorithm for ATM surveillance, which is demonstrated to be effective and efficient to handle arbitrarily occluded faces. In this algorithm, we innovatively propose to make use of the Omega shape formed by the head and shoulder of the person for head localization to tackle severe face occlusion. For this purpose, we first construct a novel energy function for elliptical head contour detection. Then, we develop a fast and robust head tracking algorithm, which utilizes the gradient and shape cues in a Bayesian framework. Lastly, to verify whether a detected head is occluded or not, we propose to fuse information from both skin color and face structure using the AdaBoost algorithm. Experimental results on real world data show that our proposed algorithm can achieve 98.64% accuracy on face detection and 98.56% accuracy on face occlusion detection, even though there are severe occlusions in faces, at a speed of up to 12 frames per second.

Zhang, T, Zou, J & Jia, W 2018, 'Fast and robust road sign detection in driver assistance systems', Applied Intelligence, vol. 48, no. 11, pp. 4113-4127.
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© 2018, Springer Science+Business Media, LLC, part of Springer Nature. Road sign detection plays a critical role in automatic driver assistance systems. Road signs possess a number of unique visual qualities in images due to their specific colors and symmetric shapes. In this paper, road signs are detected by a two-level hierarchical framework that considers both color and shape of the signs. To address the problem of low image contrast, we propose a new color visual saliency segmentation algorithm, which uses the ratios of enhanced and normalized color values to capture color information. To improve computation efficiency and reduce false alarm rate, we modify the fast radial symmetry transform (RST) algorithm, and propose to use an edge pairwise voting scheme to group feature points based on their underlying symmetry in the candidate regions. Experimental results on several benchmarking datasets demonstrate the superiority of our method over the state-of-the-arts on both efficiency and robustness.

Zhang, X, Lin, J, Chen, Z, Sun, F, Zhu, X & Fang, G 2018, 'An Efficient Neural-Network-Based Microseismic Monitoring Platform for Hydraulic Fracture on an Edge Computing Architecture.', Sensors (Basel, Switzerland), vol. 18, no. 6.
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Microseismic monitoring is one of the most critical technologies for hydraulic fracturing in oil and gas production. To detect events in an accurate and efficient way, there are two major challenges. One challenge is how to achieve high accuracy due to a poor signal-to-noise ratio (SNR). The other one is concerned with real-time data transmission. Taking these challenges into consideration, an edge-computing-based platform, namely Edge-to-Center LearnReduce, is presented in this work. The platform consists of a data center with many edge components. At the data center, a neural network model combined with convolutional neural network (CNN) and long short-term memory (LSTM) is designed and this model is trained by using previously obtained data. Once the model is fully trained, it is sent to edge components for events detection and data reduction. At each edge component, a probabilistic inference is added to the neural network model to improve its accuracy. Finally, the reduced data is delivered to the data center. Based on experiment results, a high detection accuracy (over 96%) with less transmitted data (about 90%) was achieved by using the proposed approach on a microseismic monitoring system. These results show that the platform can simultaneously improve the accuracy and efficiency of microseismic monitoring.

Zhang, X, Lv, T, Ni, W, Cioffi, JM, Beaulieu, NC & Guo, YJ 2018, 'Energy-efficient caching for scalable videos in heterogeneous networks', IEEE Journal on Selected Areas in Communications, vol. 36, no. 8, pp. 1802-1815.
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© 1983-2012 IEEE. By suppressing repeated content deliveries, wireless caching has the potential to substantially improve the energy efficiency (EE) of the fifth-generation communication networks. In this paper, we propose two novel energy-efficient caching schemes in heterogeneous networks, namely, scalable video coding (SVC)-based fractional caching and SVC-based random caching, which can provide on-demand video services with different perceptual qualities. We derive the expressions for successful transmission probabilities and ergodic service rates. Based on the derivations and the established power consumption models, the EE maximization problems are formulated for the two proposed caching schemes. By taking logarithmic approximations of the l0-norm, the problems are efficiently solved by the standard gradient projection method. Numerical results validate the theoretical analysis and demonstrate the superiority of our proposed caching schemes, compared to three benchmark strategies.

Zhang, Z, Chen, J, Wu, Q & Shao, L 2018, 'GII Representation-based cross-view gait recognition by discriminative projection with list-wise constraints', IEEE Transactions on Cybernetics, vol. 48, no. 10, pp. 2935-2947.
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© 2017 IEEE. Remote person identification by gait is one of the most important topics in the field of computer vision and pattern recognition. However, gait recognition suffers severely from the appearance variance caused by the view change. It is very common that gait recognition has a high performance when the view is fixed but the performance will have a sharp decrease when the view variance becomes significant. Existing approaches have tried all kinds of strategies like tensor analysis or view transform models to slow down the trend of performance decrease but still have potential for further improvement. In this paper, a discriminative projection with list-wise constraints (DPLC) is proposed to deal with view variance in cross-view gait recognition, which has been further refined by introducing a rectification term to automatically capture the principal discriminative information. The DPLC with rectification (DPLCR) embeds list-wise relative similarity measurement among intraclass and inner-class individuals, which can learn a more discriminative and robust projection. Based on the original DPLCR, we have introduced the kernel trick to exploit nonlinear cross-view correlations and extended DPLCR to deal with the problem of multiview gait recognition. Moreover, a simple yet efficient gait representation, namely gait individuality image (GII), based on gait energy image is proposed, which could better capture the discriminative information for cross view gait recognition. Experiments have been conducted in the CASIA-B database and the experimental results demonstrate the outstanding performance of both the DPLCR framework and the new GII representation. It is shown that the DPLCR-based cross-view gait recognition has outperformed the-state-of-the-art approaches in almost all cases under large view variance. The combination of the GII representation and the DPLCR has further enhanced the performance to be a new benchmark for cross-view gait recognition.

Zhao, H, Zhang, C, Zhang, B, Duan, P & Yang, Y 2018, 'Decomposition-based sub-problem optimal solution updating direction-guided evolutionary many-objective algorithm', Information Sciences, vol. 448-449, pp. 91-111.
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© 2018 Elsevier Inc. The many-objective optimization problem (MaOP) is a common problem in the fields of engineering and scientific computing. It requires the optimization of multiple conflicting objectives. Due to the complexity of the MaOP, its optimization requires considerable amounts of time and computation resources to execute. Moreover, demand for a general optimization method for different types of MaOPs is becoming increasingly urgent. In this paper, the reference-vector-guided evolutionary algorithm (RVEA) is modified to accelerate the optimization speed and to improve its adaptability. To achieve more rapid convergence, a sub-problem optimal solution updating direction-guided variation strategy is developed to replace the original variation strategy of the RVEA. A comparative experiment on the typical test suites verifies that the proposed method offers preferable performance. Our experiment shows that the performance of the OD-RVEA declines when optimizing MaOPs with irregular Pareto fronts (PFs). To address this issue, an adaptive reference vector adjustment strategy is designed as a means of enhancing the optimization capabilities of MaOPs with irregular PFs by adjusting the distribution of reference vectors. Our comparative experiment on test cases that involve irregular PFs shows that the algorithm that applies this strategy outperforms the algorithm that applies fixed reference vectors.

Zhao, J, Mao, X & Zhang, J 2018, 'Learning deep facial expression features from image and optical flow sequences using 3D CNN', Visual Computer, vol. 34, no. 10, pp. 1461-1475.
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© 2018, Springer-Verlag GmbH Germany, part of Springer Nature. Facial expression is highly correlated with the facial motion. According to whether the temporal information of facial motion is used or not, the facial expression features can be classified as static and dynamic features. The former, which mainly includes the geometric features and appearance features, can be extracted by convolution or other learning filters; the latter, which are aimed to model the dynamic properties of facial motion, can be calculated through optical flow or other methods, respectively. When 3D convolutional neural networks (CNNs) are introduced, the extraction of two different types of features mentioned above becomes easy. In this paper, one 3D CNN architecture is presented to learn the static and dynamic features from facial image sequences and extract high-level dynamic features from optical flow sequences. Two types of dense optical flow, which contain the tracking information of facial muscle movement, are calculated according to different image pair construction methods. One is the common optical flow, and the other is an enhanced optical flow which is called accumulative optical flow. Four components of each type of optical flow are used in experiments. Three databases, two acted databases and one nearly realistic database, are selected to conduct the experiments. The experiments on the two acted databases achieve state-of-the-art accuracy, and indicate that the vertical component of optical flow has an advantage over other components in recognizing facial expression. The experimental results on the three selected databases show that more discriminative features can be learned from image sequences than from optical flow or accumulative optical flow sequences, and the accumulative optical flow contains more motion information than optical flow if the frame distance of the image pairs used to calculate them is not too large.

Zhao, N, Yang, X, Ren, A, Zhang, Z, Zhao, W, Hu, F, Ur Rehman, M, Abbas, H & Abolhasan, M 2018, 'Antenna and Propagation Considerations for Amateur UAV Monitoring', IEEE Access, vol. 6.
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© 2013 IEEE. The broad application spectrum of unmanned aerial vehicles is making them one of the most promising technologies of Internet of Things era. Proactive prevention for public safety threats is one of the key areas with vast potential of surveillance and monitoring drones. Antennas play a vital role in such applications to establish reliable communication in these scenarios. This paper considers line-of-sight and non-line-of-sight threat scenarios with the perspective of antennas and electromagnetic wave propagation.

Zheng, BL, Wong, SW, Feng, SF, Zhu, L & Yang, Y 2018, 'Multi-Mode Bandpass Cavity Filters and Duplexer With Slot Mixed-Coupling Structure', IEEE Access, vol. 6, pp. 16353-16362.
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© 2018 IEEE. The quasi-elliptic multi-mode bandpass cavity filters and duplexer with slot mixed-coupling structure are proposed in this paper. A single metal cavity embedded with a rectangular-shaped slot-cut metal plate is utilized to constitute a multi-mode bandpass filter with a few features including wide passband, low profile and controllable transmission zeros (TZs). In this paper, the slot-cut metal plane serves as the multi-mode resonators. In detail, the slot on the metal plane functions as the circuit element to move the higher order modes within the reasonable frequency-band, while serving as a mixed-coupling structure to generate out-of-band transmission zeros. To demonstrate the multiple-mode capability in filter design, the dual-mode, triple-mode, and quadruple-mode filters are developed by appropriately allocating a few TZs in the upper stopbands using the proposed slot mixed-coupling approach, namely, Type-I filters. Next, a quadruple-mode cavity filter with both lower and higher TZs is designed, namely, Type-II filter, which is further applied for the exploration of a duplexer. Finally, the filter and duplexer prototypes are fabricated and measured. The measurement results are found in good agreement with the simulated ones.

Zheng, D, Zhang, H, Zhang, JA & Wang, G 2018, 'Consensus of multi-agent systems with faults and mismatches under switched topologies using a delta operator method', NEUROCOMPUTING, vol. 315, pp. 198-209.
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Zhong, Y, Dutkiewicz, E, Yang, Y, Zhu, X, Zhou, Z & Jiang, T 2018, 'Internet of Mission-Critical Things: Human and Animal Classification—A Device-Free Sensing Approach', IEEE Internet of Things Journal, vol. 5, no. 5, pp. 3369-3377.
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IEEE The well-known Internet-of-things is recently being considered for critical missions, such as search and rescue, surveillance and border patrol. One of the most critical issues that these applications are currently facing is how to correctly distinguish between human and animal targets in a cost-effective way. In this work, we present a relatively low-cost but robust approach that uses a combination of device-free sensing and machine-learning technologies to tackle this issue. In order to validate the feasibility of the presented approach, a variety of data is collected in a cornfield using impulse-radio ultra-wideband transceivers. These data are then used to investigate the influence of different statistical properties of the RF signal on the accuracy of human/animal target classification. Based on the probability density function of different statistical properties, two distinguishing features for target classification are found, namely standard deviation and root mean spread delay spread. Using them, the impact on the classification accuracy due to different classifiers, number of training samples and different values of signal-to-noise ratio is extensively verified. Even with the worst case, the classification accuracy of the system is still better than 91targets (including goats and dogs), which indicates that the presented approach has a great potential to be deployed in the near future.

Zhong, Y, Yang, Y, Zhu, X, Huang, Y, Dutkiewicz, E, Zhou, Z & Jiang, T 2018, 'Impact of Seasonal Variations on Foliage Penetration Experiment: A WSN-Based Device-Free Sensing Approach', IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING, vol. 56, no. 9, pp. 5035-5045.
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Zhou, S, Lin, J-Y, Wong, S-W, Deng, F, Zhu, L, Yang, Y, He, Y & Tu, Z-H 2018, 'Spoof Surface Plasmon Polaritons Power Divider with large Isolation.', Scientific reports, vol. 8, no. 1.
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Periodic corrugated metal structure is designed to support and propagate spoof surface plasmon polaritons (SSPPs) wave in the microwave frequencies. In this paper, firstly a plasmonic waveguide consisting of oval-ring shaped cells is proposed with the performance of high transmission efficiency in a wide frequency range. The coplanar waveguides (CPWs) with 50 Ω impedance are adopted to feed the energies or extract signals at both ends of the plasmonic waveguide. Then a well-isolated power divider is constructed based on the SSPPs waveguides aiming to equally split the energy of the SSPPs wave into two equal parts. The stepped-impedances are co-designed with the three input/output ports of the power divider to achieve the impedance-matching between the SSPPs waveguides and the coplanar waveguides. Besides, a single resistor is placed in the middle of two symmetrical half oval-rings to realize the isolation between the two output ports over the spectrum of 4.5-7.5 GHz. Finally, both plasmonic waveguide and the power divider are fabricated and tested to verify the predicted characteristics.

Zhou, Y, Zheng, K, Ni, W & Liu, RP 2018, 'Elastic Switch Migration for Control Plane Load Balancing in SDN', IEEE ACCESS, vol. 6, pp. 3909-3919.
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Zhu, H & Abbosh, AM 2018, 'A Compact Tunable Directional Coupler with Continuously Tuned Differential Phase', IEEE Microwave and Wireless Components Letters, vol. 28, no. 1, pp. 19-21.
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© 2001-2012 IEEE. A tunable directional coupler with outputs that have continuously tuned phase difference and constant magnitude is presented. The initial design is based on a 3-dB branch-line coupler with two arms having variable electrical lengths. To realize the variable-length lines, a novel concept of tunable phase shifting unit, which includes a pair of inductor-varactor loaded coupled lines, is proposed. By controlling the shifting phase of the two arms, the differential phase (i.e., the phase difference between the two output ports) can be tuned continuously. Explicit relation between the objective differential phase of the device and the required shifting phase of those units is analyzed and explained. To validate the design, a prototype is built, simulated, and tested. The experimental and predicted results agree well and show that the device can realize arbitrary and continuously tunable differential phase from 45° to 135°. The overall size of the design is only 0.18 λ{g} \times 0.24 λ{g} , which is extremely compact compared with using a cascaded coupler-phase shifters and is thus suitable for miniaturized wireless systems.

Zhu, H, Abbosh, AM & Guo, L 2018, 'Planar in-phase filtering power divider with tunable power division and controllable band for wireless communication systems', IEEE Transactions on Components, Packaging and Manufacturing Technology, vol. 8, no. 8, pp. 1458-1468.
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© 2011-2012 IEEE. A wideband in-phase power divider with tunable power division ratio (PDR) and filtering response is presented. The proposed design is quite compact and consists of a three-line coupled structure and loaded with a pair of varactor-loaded short-ended stubs at two output terminations. A variable power division is realized by tuning the coupling factors between the centerline and sidelines of the three-line coupled structure using a pair of varactors. A varactor at the center of the loaded short-ended stub and another one connecting the end of the stub to the ground is used to control the center frequency and band of operation. A prototype is modeled using the microstrip technique and then simulated and tested. The experimental result indicates a tunability of PDR from 0.5:1 to 2:1 across wideband range of 60% and a controllable band from 35% to 63.2%, with 13% center frequency tunability, sharp passband cutoff selectivity, as well as harmonic suppression to more than 6 GHz (4 times the center frequency). Moreover, the overall loss is around 1-1.2 dB; the isolation is more than 14 dB, whereas the differential phase is less than 7° in all the investigated cases.

Zhu, H, Sun, HH, Jones, B, Ding, C & Guo, YJ 2018, 'Wideband Dual-Polarized Multiple Beam-Forming Antenna Arrays', IEEE Transactions on Antennas and Propagation.
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IEEE Wideband multi-beam antenna arrays based on three-beam Butler matrices are presented in this paper. The proposed beam-forming arrays are particularly suited to increasing the capacity of 4G long-term evolution (LTE) base stations. Although dual-polarized arrays are widely used in LTE base stations, analogue beam-forming arrays have not been realized before, due to the huge challenge of achieving wide operating bandwidth and stable array patterns. To tackle these problems, for the first time, we present a novel wideband multiple beam-forming antenna array based on Butler matrices. The described beam-forming networks produce three beams but the methods are applicable to larger networks. The essential part of the beam-forming array is a wideband three-beam Butler matrix, which comprises quadrature couplers and fixed wideband phase shifters. Wideband quadrature and phase shifters are developed using striplines, which provide the required power levels and phase differences at the outputs. To achieve the correct beamwidth and to obtain the required level of crossover between adjacent beams, beam-forming networks consisting of augmented three-beam Butler matrices using power dividers are presented to expand the number of output ports from three to five or six. Dual-polarized, three-beam antenna arrays with five and six elements covering LTE band are developed. Prototypes comprising beam-forming networks and arrays are tested according to LTE base station specification. The test results show close agreement with the simulation ones and compliance with LTE requirements. The designs presented are applicable to a wide range of wideband multi-beam arrays.

Zhu, H, Yang, Y, Zhu, X, Sun, Y & Wong, SW 2018, 'Miniaturized resonator and bandpass filter for silicon-based monolithic microwave and millimeter-wave integrated circuits', IEEE Transactions on Circuits and Systems I: Regular Papers, vol. 65, no. 12, pp. 4062-4071.
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© 2018 IEEE. This paper introduces a unique approach for the implementation of a miniaturized on-chip resonator and its application for the first-order bandpass filter (BPF) design. This approach utilizes a combination of a broadside-coupling technique and a split-ring structure. To fully understand the principle behind it, simplified LC equivalent-circuit models are provided. By analyzing these models, guidelines for implementation of an ultra-compact resonator and a BPF are given. To further demonstrate the feasibility of using this approach in practice, both the implemented resonator and the filter are fabricated in a standard 0.13-μm (Bi)-CMOS technology. The measured results show that the resonator can generate a resonance at 66.75 GHz, while the BPF has a center frequency at 40 GHz and an insertion loss of 1.7 dB. The chip size of both the resonator and the BPF, excluding the pads, is only 0.012mm2 (0.08 × 0.144 mm2).

Zhu, H, Zhu, X, Yang, Y & Xue, Q 2018, 'Design of Wideband Third-Order Bandpass Filters Using Broadside-Coupled Resonators in 0.13-μm (Bi)-CMOS Technology', IEEE Transactions on Microwave Theory and Techniques, vol. 66, no. 12, pp. 5593-5604.
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© 2018 IEEE. In this paper, two third-order bandpass filters (BPFs) designed for millimeter-wave applications are presented. Unlike previously published ones, the proposed designs use a "cell-based" approach, which utilizes identical broadside-coupled resonators (BCRs) with series and shunt capacitors. The capacitors are mainly used as J -inverters to achieve the desired frequency responses. To fully understand the operational mechanism of the presented approach, both the BCR and BPFs are analyzed using the simplified LC-equivalent circuit models. To prove the concept, both BPFs are implemented in a standard 0.13- μm silicon-germanium bipolar complementary metal-oxide-semiconductor technology. According to the on-wafer measurement results, the BPFs exhibit the excellent performance including flat in-band responses with relatively large harmonic suppression. The first design has a 1-dB bandwidth from 23.9 to 39.7 GHz with an insertion loss of 3.9 dB at the center frequency of 31 GHz. The stopband attenuation is better than 45 dB at 58 GHz. The 1-dB bandwidth of the second design covers from 26.7 to 44.3 GHz with an insertion loss of 3.1 dB at the center frequency of 35 GHz, and stopband attenuation up to 35 dB is achieved at 59 GHz. Both designs occupy an identical area of 0.073 mm 2 (0.248×0.294 mm 2 ), excluding the G-S-G testing pads.

Zhu, J, Li, S, Deng, L, Zhang, C, Yang, Y & Zhu, H 2018, 'Broadband tunable terahertz polarization converter based on a sinusoidally-slotted graphene metamaterial', Optical Materials Express, vol. 8, no. 5, pp. 1164-1173.
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© 2018 Optical Society of Americaunder. A new wideband sinusoidally-slotted graphene-based cross-polarization converter (CPC) is proposed in this paper. The proposed polarization converter can realize a broadband terahertz polarization conversion from 1.28 to 2.13-THz with a polarization conversion ratio (PCR) of more than 0.85. Taking advantage of the gradient width modulation of the graphene-based unit structure, the continuous plasmon resonances are excited at the edges of the sinusoidal slot. Therefore, the proposed converter can achieve a broadband polarization conversion in a simplified structure. Furthermore, the polarization conversion characteristics of the CPC are insensitive to the incident angle. The PCR remains more than 0.85 with little bandwidth degradation even as the incident angle increases to as high as 50°. More importantly, the operating bandwidth and the magnitude of the PCR can be tuned easily by adjusting the chemical potential and the electron scattering times of the graphene. In a way, we believe this kind of graphene-based polarization converter can enrich the polarization conversion community for realizing broadband and tunable polarization conversion.

Zhu, J, Li, S, Liao, S, Yang, Y & Zhu, H 2018, '60 GHz Substrate-Integrated-Waveguide-Fed Patch Antenna Array with Quadri-Polarization', IEEE Transactions on Antennas and Propagation, vol. 66, no. 12, pp. 7406-7411.
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© 1963-2012 IEEE. This communication presents a new design of a quadri-polarization-agile aperture-coupled patch antenna array for 60 GHz applications. Four polarization states, namely, vertical linear polarization, horizontal linear polarization, left-hand circular polarization (LHCP), and right-hand circular polarization (RHCP) can be flexibly reconfigured by dynamically switching the excitation of the corresponding port. More importantly, as the LP and CP radiations are achieved by using differential feeding and sequential-rotation feeding, respectively, the array exhibits wide impedance and axial ratio (AR) bandwidths, high polarization purity as well as symmetrical pattern with the main beam fixed at boresight. The-10 dB impedance bandwidths are better than 11.6% (57-64 GHz) for the four polarization states. The measured AR bandwidths are from 58 to more than 64 GHz for both the LHCP and RHCP. The good radiation performance together with the quadri-polarization-agile capability of this new array, as demonstrated in the communication, underlines its suitability for the future 5G communication systems, especially in a multipath propagation environment.

Zhu, J, Liao, S, Yang, Y, Li, S & Xue, Q 2018, '60 GHz Dual-Circularly Polarized Planar Aperture Antenna and Array', IEEE Transactions on Antennas and Propagation, vol. 66, no. 2, pp. 1014-1019.
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© 1963-2012 IEEE. This communication presents new designs of dual-circularly polarized (CP) planar aperture antenna and array for 60 GHz applications. First, a four-port planar aperture antenna with its feeding network is developed that exhibits wide impedance bandwidth, dual-CP radiation as well as high gain. Then, based on the proposed antenna, a new scheme of building a dual-CP array is proposed. With this new scheme that combines the power splitting network and series feeding method, four sequentially fed antenna elements are successfully combined to form a CP radiation array. The experimental results show that the -10 dB impedance bandwidths of the antenna and the array are more than 18.2% (55-66 GHz). While the 3 dB axial ratio bandwidths are from 54.2 to 64.3 GHz (17.2%) for the antenna and from 54.8 to 65 GHz (17%) for the array. The maximum gains achieved are 13.7 and 17.85 dBic for the antenna and array, respectively.

Zhu, J, Yang, Y & Li, S 2018, 'A photo-excited broadband to dual-band tunable terahertz prefect metamaterial polarization converter', Optics Communications, vol. 413, pp. 336-340.
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© 2018 Elsevier B.V. A new and simple design of photo-excited broadband to dual-band tunable terahertz (THz) metamaterial cross polarization converter is proposed in this paper. The tunable converter is a sandwich structure with the center-cut cross-shaped metallic patterned structure as a resonator, the middle dielectric layer as a spacer and the bottom metallic film as the ground. The conductivity of the photoconductive semiconductor (Silicon) filled in the gap of the cross-shaped metallic resonator can be tuned by the incident pump power, leading to an easy modulation of the electromagnetic response of the proposed converter. The results show that the proposed cross-polarization converter can be tuned from a broadband with polarization conversion ratio (PCR) beyond 95% (1.86–2.94 THz) to dual frequency bands (fl=1.46 THz & fh=2.9 THz). The conversion peaks can reach 99.9% for the broadband and, 99.5% (fl) and 99.7% (fh) for the dual-band, respectively. Most importantly, numerical simulations demonstrate that the broadband/dual-band polarization conversion mechanism of the converter originates from the localized surface plasmon modes, which make the design simple and different from previous designs. With these good features, the proposed broadband to dual-band tunable polarization converter is expected to be used in widespread applications.

Zhu, M, He, B & Wu, Q 2018, 'Single Image Dehazing Based on Dark Channel Prior and Energy Minimization', IEEE Signal Processing Letters, vol. 25, no. 2, pp. 174-178.
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Ziolkowski, RW 2018, 'Advances in Reconfigurable Antenna Systems Facilitated by Innovative Technologies', IEEE Access, vol. 6, pp. 5780-5794.
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© 2013 IEEE. Future fifth generation (5G) wireless platforms will require reconfigurable antenna systems to meet their performance requirements in compact, light-weight, and cost-effective packages. Recent advances in reconfigurable radiating and receiving structures have been enabled by a variety of innovative technology solutions. Examples of reconfigurable partially reflective surface antennas, reconfigurable filtennas, reconfigurable Huygens dipole antennas, and reconfigurable feeding network-enabled antennas are presented and discussed. They represent novel classes of frequency, pattern, polarization, and beam-direction reconfigurable systems realized by the innovative combinations of radiating structures and circuit components.

Zuo, Y, Wu, Q, An, P & Shang, X 2018, 'Integrated cosparse analysis model with explicit edge inconsistency measurement for guided depth map upsampling', Journal of Electronic Imaging, vol. 27, no. 4.
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© 2018 SPIE and IS & T. A low-resolution depth map can be upsampled through the guidance from the registered high-resolution color image. This type of method is so-called guided depth map upsampling. Among the existing methods based on Markov random field (MRF), either data-driven or model-based prior is adopted to construct the regularization term. The data-driven prior can implicitly reveal the relation between color-depth image pair by training on external data. The model-based prior provides the anisotropic smoothness constraint guided by high-resolution color image. These types of priors can complement each other to solve the ambiguity in guided depth map upsampling. An MRF-based approach is proposed that takes both of them into account to regularize the depth map. Based on analysis sparse coding, the data-driven prior is defined by joint cosparsity on the vectors transformed from color-depth patches using the pair of learned operators. It is based on the assumption that the cosupports of such bimodal image structures computed by the operators are aligned. The edge inconsistency measurement is explicitly calculated, which is embedded into the model-based prior. It can significantly mitigate texture-copying artifacts. The experimental results on Middlebury datasets demonstrate the validity of the proposed method that outperforms seven state-of-the-art approaches.

Zuo, Y, Wu, Q, Zhang, J & An, P 2018, 'Explicit Edge Inconsistency Evaluation Model for Color-guided Depth Map Enhancement', IEEE Transactions on Circuits and Systems for Video Technology.
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Color-guided depth enhancement is to refine depth maps according to the assumption that the depth edges and the color edges at the corresponding locations are consistent. In the methods on such low-level vision task, Markov Random Fields (MRF) including its variants is one of major approaches, which has dominated this area for several years. However, the assumption above is not always true. To tackle the problem, the state-of-the-art solutions are to adjust the weighting coefficient inside the smoothness term of MRF model. These methods are lack of explicit evaluation model to quantitatively measure the inconsistency between the depth edge map and the color edge map, so it cannot adaptively control the efforts of the guidance from the color image for depth enhancement leading to various defects such as texture-copy artifacts and blurring depth edges. In this paper, we propose a quantitative measurement on such inconsistency and explicitly embed it into the smoothness term. The proposed method demonstrates the promising experimental results when compared with benchmark and the state-of-the-art methods on Middlebury datasets, ToF-Mark datasets and NYU datasets.

Zuo, Y, Wu, Q, Zhang, J & An, P 2018, 'Minimum Spanning Forest with Embedded Edge Inconsistency Measurement Model for Guided Depth Map Enhancement', IEEE Transactions on Image Processing, vol. 27, no. 8, pp. 4145-4159.
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© 1992-2012 IEEE. Guided depth map enhancement based on Markov random field (MRF) normally assumes edge consistency between the color image and the corresponding depth map. Under this assumption, the low-quality depth edges can be refined according to the guidance from the high-quality color image. However, such consistency is not always true, which leads to texture-copying artifacts and blurring depth edges. In addition, the previous MRF-based models always calculate the guidance affinities in the regularization term via a non-structural scheme, which ignores the local structure on the depth map. In this paper, a novel MRF-based method is proposed. It computes these affinities via the distance between pixels in a space consisting of the minimum spanning trees (forest) to better preserve depth edges. Furthermore, inside each minimum spanning tree, the weights of edges are computed based on the explicit edge inconsistency measurement model, which significantly mitigates texture-copying artifacts. To further tolerate the effects caused by noise and better preserve depth edges, a bandwidth adaption scheme is proposed. Our method is evaluated for depth map super-resolution and depth map completion problems on synthetic and real data sets, including Middlebury, ToF-Mark, and NYU. A comprehensive comparison against 16 state-of-the-art methods is carried out. Both qualitative and quantitative evaluations present the improved performances.

Abeywickrama, HV, Jayawickrama, BA, He, Y & Dutkiewicz, E 2018, 'Potential field based inter-UAV collision avoidance using virtual target relocation', IEEE Vehicular Technology Conference, pp. 1-5.
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© 2018 IEEE. Unmanned Aerial Vehicles (UAV) are becoming popular in a range of areas. This has given rise to the concept of UAV swarms, where multiple UAVs act together to achieve a common task. With multiple UAVs flying in close proximity to each other, sharing the same airspace, the risk of inter-UAV collisions increases. It's important to avoid these collisions while having minimal impact on the UAV system. We propose a novel Potential Field Method (PFM) based algorithm for inter-UAV collision avoidance which considerably reduces the total time taken by the UAV system to achieve its goal. We control the collision avoidance actions of the UAVs by virtually relocating their targets. The positions of the virtual targets are calculated to minimize the collision probability, based on a probability function we introduced. The proposed algorithm reduces the total system time approximately by 20\% as opposed to the traditional PFM.

Ajayan, AR, Al-Doghman, F & Chaczko, Z 2018, 'Visualizing Multimodal Big Data Anomaly Patterns in Higher-Order Feature Spaces', 2018 26th International Conference on Systems Engineering (ICSEng), International Conference on Systems Engineering, IEEE, Sydney, NSW, Australia.
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The world today, as we know it, is profuse with information about humans and objects. Datasets generated by cyber-physical systems are orders of magnitude larger than their current information processing capabilities. Tapping into these big data flows to uncover much deeper perceptions into the functioning, operational logic and smartness levels attainable has been investigated for quite a while. Knowledge Discovery & Representation capabilities across mutiple modalities holds much scope in this direction, with regards to their information holding potential. This paper investigates the applicability of an arithmetic tool Tensor Decompositions and Factorizations in this scenario. Higher order datasets are decomposed for Anomaly Pattern capture which encases intelligence along multiple modes of data flow. Preliminary investigations based on data derived from Smart Grid Smart City Project are compliant with our hypothesis. The results proved that Abnormal patterns detected in decomposed Tensor factors encompass deep information energy content from Big Data as efficiently as other Pattern Extraction and Knowledge Discovery frameworks, while salvaging time and resources.

Al-Doghman, F, Chaczko, Z & Brookes, W 2018, 'Adaptive Consensus-based Aggregation for Edge Computing', 2018 26th International Conference on Systems Engineering (ICSEng), International Conference on Systems Engineering, IEEE, Sydney, Australia.
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Alzughaibi, A & Chaczko, Z 2018, 'A precise human detection model using combination of feature extraction techniques in a dynamic environment', International Conference Image and Vision Computing New Zealand, pp. 1-6.
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© 2017 IEEE. This research paper presents a Machine Learning-based human detection model focusing on improving precision of human movement conditions in video frames. The problem is addressed by focusing on pre-processing and an efficient feature extraction methodology. Combination of features are extracted, including histograms of gradients (HoG), histograms of colors (HoC), and histograms of bars (HoB). These featuresets are combined to form the finall feature vector that describes the human shape, and the Support Vector Machine (SVM)-based classifier is used for classification purposes. Improving the precision will allow the human movement detector to make better detections by reducing false positives and missed detections, which are the problems faced by current detection techniques. Training of the algorithm is done using the INRIA dataset and tested on sequences depicting conditions of moving humans in different environments. In the testing phase, the search space is reduced using an upper body detector, which is done using haar features. The reduced space is used to carry out human detection using the proposed feature extraction technique. The proposed detector approach performs well, and the number of missed detections are reduced. However, some false detections are still performed, but this is due the fact that some objects resemble humans. The proposed model is benchmarked with the current state-of-the-art detectors using a challenging test dataset, which is used to test the performance. The Receiver Operating Characteristic (ROC) curves for the precision-recall and true-positive rates are plotted to compare and evaluate the results. The proposed model outperforms most of the current state-of-the-art detectors.

Amirgholipour, S, He, X, Jia, W, Wang, D & Zeibots, M 2018, 'A-CCNN: Adaptive CCNN for Density Estimation and Crowd Counting', 2018 25th IEEE International Conference on Image Processing (ICIP), Athens, Greece, pp. 948-952.
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Bah, AO, Ziolkowski, RW, Qin, PY & Guo, YJ 2018, 'Design and Analysis of a Wide Angle Impedance Matching Metasurface for Wideband Antenna Arrays', IEEE, European Conference on Antennas and Propagation, London.
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A wide bandwidth, low profile, double sided, wide angle impedance matching metasurface is reported. It alleviates the well-known problem of impedance mismatch caused by mutual coupling when an array is in its scan mode. Each unit cell of the metasurface contains two multi-resonant, tightly-coupled unequal arm Jerusalem cross elements on the top and bottom sides of a thin substrate. Each element consists of two orthogonal capacitively loaded strips. The wide bandwidth of the metasurface is achieved by tightly coupling these multi-resonant elements. The metasurface is capable of facilitating wide angle scanning over a 6:1 impedance bandwidth without the need for bulky dielectrics or multi-layered structures.

Bautista, MG, Hora, J & Dutkiewicz, E 2018, 'Design Methodology of a Miniaturized Millimetre Wave Integrated Passive Resonator Using (Bi)-CMOS Technology', ISCIT 2018 - 18th International Symposium on Communication and Information Technology, pp. 275-277.
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© 2018 IEEE. In this paper, a design methodology of a miniaturized passive resonator implemented in SiGe technology is presented. The planar structure is implemented using the topmost metal layer of the process technology to minimize the conductor loss and achieved a compact size. The physical dimension is carefully tuned to optimize the coupling capacitance between the horizontal and vertical space between each metal strip. The principle of a spiral meander line structure has been studied and applied in the new miniaturization technique develop in this paper.

Bautista, MG, Zhang, XP, Zhu, X & Dutkiewicz, E 2018, 'Design of On-Chip Edge-Coupled Resonator and Its Application for Bandpass Filter in CMOS Technology', ISCIT 2018 - 18th International Symposium on Communication and Information Technology, pp. 137-140.
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© 2018 IEEE. In this work, the design of a compact on-chip edge-coupled resonator is presented. To understand the insight of the presented resonator, a simplified LC-equivalent circuit model is provided, and electromagnetic simulation is utilized for performance optimization. To demonstrate the potential of the presented resonator, a bandpass filter design example is also given. By taking advantage of using metal-insulator-metal capacitors, a compact filter can be designed. For proving of concept, both the presented resonator and filter are implemented and fabricated using standard CMOS technology. A good agreement between simulation and measurement has been achieved. The measured results show that the filter has a resonance at 35.4 GHz with an insertion loss of 1.7 dB and greater than-10 dB of return loss. The miniaturized chip area of both the resonator and the BPF, excluding the pads, is only 0.039 mm 2 (0.15 × 0.26 mm 2 ).

Bou Ghantous, G & Gill, AQ 2018, 'DevOps Reference Architecture for Multi-Cloud IOT Applications', International Conference on Business Informatics, IEEE, Vienna, Austria..
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There is a growing interest among organizations in adopting DevOps approach for IoT (Internet of Things) applications. However, the challenge is: how to apply DevOps when a multi-cloud heterogeneous environment is required for IoT application. This paper aims to addresses this important challenge and proposes a DevOps Reference Architecture (DRA) to deploy IoT-applications on multi-cloud. The proposed architecture is evaluated by the means of a case study, which involves deploying an IoT application on the chosen set of clouds. The results of this initial evaluation indicate that the proposed architecture would help practitioners and researchers to understand the usefulness and applicability of DevOps approach on multi-cloud platform for automating IoT application deployment.

Braun, R, Miller, G, Chaczko, Z & Brookes, W 2018, 'First experiences of Studios in the new Data Engineering program', 2018 17th International Conference on Information Technology Based Higher Education and Training (ITHET), IEEE, pp. 1-5.

Cai, H, Jiang, H, Huang, X, Yang, J & He, X 2018, 'Violence detection based on spatio-temporal feature and fisher vector', Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics), Chinese Conference on Pattern Recognition and Computer Vision, Springer, Guangzhou, China, pp. 180-190.
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© Springer Nature Switzerland AG 2018. A novel framework based on local spatio-temporal features and a Bag-of-Words (BoW) model is proposed for violence detection. The framework utilizes Dense Trajectories (DT) and MPEG flow video descriptor (MF) as feature descriptors and employs Fisher Vector (FV) in feature coding. DT and MF algorithms are more descriptive and robust, because they are combinations of various feature descriptors, which describe trajectory shape, appearance, motion and motion boundary, respectively. FV is applied to transform low level features to high level features. FV method preserves much information, because not only the affiliations of descriptors are found in the codebook, but also the first and second order statistics are used to represent videos. Some tricks, that PCA, K-means++ and codebook size, are used to improve the final performance of video classification. In comprehensive consideration of accuracy, speed and application scenarios, the proposed method for violence detection is analysed. Experimental results show that the proposed approach outperforms the state-of-the-art approaches for violence detection in both crowd scenes and non-crowd scenes.

Cai, Z, Lin, J, Zhang, T, Yang, Y, Liu, Y & Tang, X 2018, 'A low phase noise VCO employing tunable stubs loaded nested split-ring resonator', 2018 Australian Microwave Symposium, AMS 2018 - Conference Proceedings, Australian Microwave Symposium, IEEE, Brisbane, QLD, Australia, pp. 57-58.
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© 2018 IEEE. In this paper, a low phase noise VCO employing tunable stubs loaded nested split-ring resonator (SLNSRR) has been proposed By loading anti-pair varactors at each side of the SLNSRR, the center frequency of the SLNSRR filter can be tuned from 1.82 GHz to 2.18 GHz. In the oscillator design, the tunable SLNSRR filter is used as a frequency stable element to select the oscillation frequency while keeping the low phase noise performance. To validate the method, an L-band to S-band VCO is designed, fabricated and measured. The measured results show that the proposed VCO has a frequency tuning range from 1.787 GHz to 2.117 GHz with a 16.9 % bandwidth. Over this frequency range, the phase noises measured at 1 MHz frequency offset are better than -113.49 dBc/Hz.

Cai, Z, Tang, X, Zhang, T & Yang, Y 2018, 'An X-band Low Phase Noise Oscillator with High Harmonic Suppression Using SIW Quarter-Wavelength Resonator', IEEE MTT-S International Microwave Symposium Digest, IEEE/MTT-S International Microwave Symposium, IEEE, Philadelphia, PA, USA, pp. 427-430.
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© 2018 IEEE. This paper presents a low phase noise oscillator with high harmonic suppression employing a pair of substrate integrated waveguide (SIW) quarter-wavelength resonators (QWR) in the feedback loop of the oscillator. By tuning the width of the SIW-QWR based filter, the stopband bandwidth can be extended while maintaining the high group delay in the passband. Taking advantages of the proposed SIW-QWR, an X-band low phase noise oscillator with the second and third harmonic suppression is designed, fabricated and tested. The measured results show that the oscillator operates at 8.08 GHz with -2.14 dBm output power. The second and third harmonic suppression of the presented oscillator can reach to 39.23 dB and 67.64 dB, respectively, with a single SIW-QWR filter. The phase noise performance of the proposed oscillator are -109.94 dBc/Hz at 100 kHz frequency offset and - 130.36 dBc/Hz at 1 MHz frequency offset, respectively.

Canning, J 2018, '3D printing, photonics and the IoT', https://www.osapublishing.org/conference.cfm?meetingid=89&yr=2018, Conf. lasers & Electro-Optics Pac. Rim, OSA, Hong Kong.
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3D-printing is changing the way research is being conducted. By enabling the ready demonstration of prototype devices and instruments, 3D printing accelerates the adaptation of IoT technologies going beyond simple, latency-enhancing sensors. Prototyping and custom packaging is easier, rapid and increasingly low cost, circumventing traditional approaches, disrupting manufacture. Direct 3D printing of transmission and optical technologies such as optical fibres and waveguides is revolutionising research, enabling accessible and affordable capability to a much wider audience space.

Canning, J 2018, '3D Printing, Photonics and the IoT', Emerging Innovation Summit 2018, Melbourne.
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Personnel https://eis18.org/speakers.html

Canning, J 2018, 'Photonics and Space', DEfence Innovation Network on Space Workshop, Sydney.

Canning, J 2018, 'Photonics in Smart Sensing Networks', IEEE, IEEE Int. Conf. on Systems Engineering, IEEE, Sydney.
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Canning, J 2018, 'Top up and top down: self-assembling and 3D printing custom photonic waveguides and components”, (KEYNOTE),', International Conference on Emerging Advanced Nanomaterials,, Newcastle.
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https://www.newcastle.edu.au/events/faculty-of-engineering-and-built-environment/3rd-international-conference-on-emerging-advanced-nanomaterials

Canning, J & Cook, K 2018, 'Monitoring Australian Utility Poles', Asia Pacific Optical Sensors, Matsue Japan.
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Canning, J, Baccini, D, Hinckley, S, Cook, K, Allwood, G, Wild, G, Davies, J & Banos, C 2018, 'Gamma irradiation effects in photonic crystal fibre Bragg gratings', http://aip2018.org.au/wp-content/uploads/2018/12/AIPCongress2018_Program-as-at-101218.pdf, Australian Institute of Physics (AIP) Congress,, Perth.
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Canning, J, Bhattacharya, S, Biswas, P & Bandyopadhyay, S 2018, 'Investigations on annealing for optimal Bragg grating Regeneration', Asia Commun. & Phot. Conf, Hangzhou China.
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Canning, J, Cook, K, Flanagan, P, Luo, Y & Peng, G-D 2018, '3D Printing Ribs, Fibres and Things INVITED', Asia Commun. & Phot. Conf.,, Hangzhou China.
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http://www.acp2018.net/uploadfile/2018/1023/20181023010106561.pdf

Canning, J, Flanagan, P & Cook, K 2018, '3D Printed Photonic Ribs: a new platform for devices, sensors and more', Asia Pacific Optical Sensors, Matsue, Japan.
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Recent progress in the field of 3D-printed photonic devices and their tremendous potential in sensing applications is reviewed. This truly disruptive technology has led to the realization of polymer optical fibres made from 3D-printed preforms, planar rib waveguides, lens arrays and prisms, all precursors for coming 3D printing of silica and other components.

Canning, J, Golzan, M & Ast, S 2019, 'The Photonics IoT and Health', Asia Pacific Opt. Sensors, Matsue Japan.
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Canning, J, Luo, Y, Chu, Y, Cook, K, Tafti, G, Wang, S, Tian, Y & Peng, G-D 2018, 'Spun High Birefringence Bismuth/Erbium Co-Doped Photonic Crystal Fibre with Broadband Polarized Emission', Asia Communications and Photonics Conference, IEEE, Hangzhou, China.
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https://www.osa.org/en-us/meetings/global_calendar/events/asia_communications_and_photonics_conference/

Canning, J, Tafti, G, Wang, W, Luo, Y, Cook, K & Peng, G-D 2018, 'Simple modelling of structured optical fibre drawing', https://www.osapublishing.org/conference.cfm?meetingid=57&yr=2018, Optical Fibre Sensors, Laussanne.
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Cao, Y & Veitch, D 2018, 'Network Timing, Weathering the 2016 Leap Second', Proceedings - IEEE INFOCOM, pp. 1826-1834.
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© 2018 IEEE. We collect high resolution timing packet data from 459 public Stratum-1 NTP servers during the leap second event of Dec. 2016, including all those participating in the NTP Pool Project, using a testbed with GPS and atomic clock synchronized DAG cards. We report in detail on a wide variety of anomalous behaviors found both at the NTP protocol level, and in the detailed timestamp performance of the server clocks themselves, which can last days or even weeks after the event. Overall, only 37.3% of servers had Adequate performance overall.

Casareo, K & Chaczko, Z 2018, 'Beacon-Based Localization Middleware for Tracking in Medical and Healthcare Environments', International Symposium on Medical Information and Communication Technology, ISMICT.
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© 2018 IEEE. This research paper proposes a Middleware model for a Localization System that may be applied in Healthcare environments such as Hospitals or Nursing Homes to track staff, patients, visitors and equipment. It investigates literature regarding indoor localization methods and limitations to determine a suitable algorithm that may be implemented in an infrastructure oriented software. The methodology used to build and test the software is explained. It then illustrates the concept of the Localization Middleware and how it might be used when deployed indoor premises, inside such rooms as a hospital wards, In terms of the functional responsibilities, it is expected to offer an effective implementation of the distance measurement algorithm for Received Signal Strength and the Linear Least-Squares localization algorithm. The simulations of the localization algorithm with the given simulation results are looking promising. However, the real-time tests demonstrated that the range measurement was insufficiently precise to be reliable. Given a more accurate and reliable distance measurement, a more precise localization result could be attained.

Chaczko, Z, Carrion Gordon, L & Bozejko, W 2017, 'The Metamodel of Heritage Preservation for Medical Big Data', Computer Aided Systems Theory – EUROCAST 2017 (LNCS), International Conference on Computer Aided Systems Theory, Spronger, Las Palmas de Gran Canaria, Spain, pp. 366-371.
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At present the real challenge of Digital Data Preservation concerns methods of keeping all important attributes of the data and preserving their originality. The key is to keep the living part of the data. It is the essence of the Heritage concept. The Heritage is about the concrete data the concept gives the interconnection to other aspects of the reality. Nowadays the physical value and the aspects of items complete the relevance of information. But the question is what is heritage and which parameters defining the artifact or the information as a heritage? The context and the interpretation of data is the answer. The heritage term is defining as the crucial and central part of the presented research. Big data analytics in healthcare is evolving into a promising field for providing insight from very large data sets and improving outcomes while reducing costs.

Chaczko, Z, Kale, A, Santana-Rodriguez, JJ & Suarez-Araujo, CP 2018, 'Towards an IOT Based System for Detection and Monitoring of Microplastics in Aquatic Environments', INES 2018 - IEEE 22nd International Conference on Intelligent Engineering Systems, Proceedings, pp. 000057-000062.
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© 2018 IEEE. Monitoring presence of micro-plastics in the ocean and fresh waters is an important research topic due to a need to preserve marine ecosystem. Microplastics represent threats to living organisms, producing harmful effects, ultimately also having an impact on humans through the food-chain. Use of laboratory-based and in situ techniques do help in investigating density and scale of this kind of pollutants. The in-situ sensing techniques are gaining popularity due to automation and continuous availability. These techniques though need an accurate hardware and efficient computing model to achieve desired success. Here, we propose an IoT based system called 'SmartIC' using specialized sensors and intelligent computing tools, specifically designed for in-situ monitoring of microplastics in natural aquatic environments. This paper is focused on system architecture, monitoring process and outline of experimental work. The initial research provides very promising results. A further course of the investigation with validation will be conducted in future to establish the proposed system completely.

Chaczko, Z, Klempous, R, Nikodem, J & Rozenblit, J 2018, '24/7 Model of Collaborative Engineering', INES 2018 - IEEE 22nd International Conference on Intelligent Engineering Systems, Proceedings, pp. 000013-000014.
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© 2018 IEEE. This paper presents a short overview of pioneering work on the 24/7 model of collaborative engineering and its practical applications in software development domain. The primary goal of the approach was to enable students, engineers and researchers to practice collaboration in virtual space. The secondary goal was to learn how to cooperatively manage and execute engineering projects more efficiently and on-time. The model relies on collaborative and consensus based agreements among geographically distributed institutions. These institutions agree to participate in cooperative and continuous (24/7) mode of operation where participating teams execute interdisciplinary tasks across different geographic, temporal and cultural zones. The interest in various collaborative models is steadily increasing. The idea has been adopted by many sectors of the industry, research and education, allowing for smart logistics and transportation, interdisciplinary product development, manufacturing design, global monitoring, international enterprise collaboration and many other applications. This paper explains the key concepts, the methodology, projects undertaken and tools developed during many years of collaboration between several prestigious educational institutions.

Chaczko, Z, Slehar, S & Shnoudi, T 2018, 'Game-Theory Based Cognitive Radio Policies for Jamming and Anti-Jamming in the IoT', International Symposium on Medical Information and Communication Technology, ISMICT.
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© 2018 IEEE. The Cognitive Radio can be considered as a mandatory part of the Internet of Things applications. It helps to solve the sacristy issues in the frequency bands of the wireless network component of the technology. However, the security problem is the primary challenge that needs to be carefully mitigated. Specifically, defending the Cognitive Radio mechanism against the jamming attacks. The aim this research paper is to investigate and provide a reliable and adaptive Cognitive Radio protection methods against the jamming attacks. Thus, improving the performance of the wireless network of IoT technology, enhancing the bandwidth and solving the issue of the sacristy of the frequency bands. The mentioned objectives will be accomplished by the aid of the game theory which is modelled as an anti-jamming game and by adapting the multi-arm bandit (MAB) policies. However, to solve the sacristy issue in the frequency band spectrum of the cognitive radio, some MAB policies were adapted such as Upper Confidence Bound (UCB), Thompson Sampling and Kullback-Leibler Upper Confidence Bound (KL-UCB). The results show some improvements and enhancements to the sacristy problem in the frequency band spectrum. To conclude, the Thompson Sampling MAB policy was the best to be adapted for solving the problem, as it resulted with lowest regrets and highest rewards compared to the other MAB policies.

Chaczko, Z, Wazirali, R, Gordon, LC & Bożejko, W 2018, 'Steganographic data heritage preservation using sharing images app', Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics), pp. 150-156.
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© Springer International Publishing AG 2018. With the advent of smartphones, we have the ability to take a photo and upload it to the internet whenever we desire. Hence, it may be of key importance to include metadata of the image for heritage preservation. This project focuses on heritage concepts and their importance in every evolving and changing digital domain where system solutions have to be sustainable, sharable, efficient and suitable to the basic user needs. Steganography provides a feasible and viable solution to ensure secure heritage preservation of the multimedia content. By embedding information directly into the image, the information about the image will never be lost, as it is not separated from its original source. The aim of the paper is to demonstrate this aspect via an image sharing app that allows users to exchange messages and personalized information that is embedded in the image such that it is inaccessible without knowing their keys.

Chehrazad, S, Aghdasi, HS, Shariati Moghadam, N & Abolhasan, M 2018, 'Addressing coverage problem in wireless sensor networks based on evolutionary algorithms'.

Chemalamarri, VD, Braun, R, Lipman, J & Abolhasan, M 2018, 'A Multi-agent Controller to enable Cognition in Software Defined Networks', 2018 28th International Telecommunication Networks and Applications Conference (ITNAC), IEEE, pp. 1-5.
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Chen, SL, Lin, W, Qin, PY, Jay Guo, Y & Ziolkowski, RW 2018, 'A novel low-profile wideband reconfigurable CP antenna array', IET Conference Publications.
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© Institution of Engineering and Technology.All Rights Reserved. For future wireless communications, cost-effective, low-profile circular polarization (CP) antennas with wide bandwidth and high directivity are highly desirable to increase system capacity and suppress polarization mismatch. In this paper, a wideband circular polarization antenna array integrated with a polarization-independent artificial magnetic conductor (AMC) is reported that meets the demands. First, a wideband CP reconfigurable antenna with a pair of cross-bowtie radiators and a metal ground is presented to achieve a fractional bandwidth of 35.9%. By replacing the metal ground with a polarization-independent AMC ground, the antenna profile is reduced from 0.25λ0 to 0.05λ0 with only a slight bandwidth decrease. A wideband CP reconfigurable 4-element linear array is achieved using four of those elements. It is low profile (0.05 λ0), and has a wide operating bandwidth (21.7%), and a high realized gain (13 dBic).

Chen, X, Kong, X & Xu, M 2018, 'Road Vehicle Recognition Using Magnetic Sensing Feature Extraction and Classification'.
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Cheng, P, Chen, Z, Zhang, JA, Li, Y & Vucetic, B 2018, 'Low-complexity precoding for spatial modulation', IEEE Vehicular Technology Conference, pp. 1-5.
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© 2017 IEEE. In this paper, we investigate linear precoding for spatial modulation (SM) over multiple-input-multiple-output (MIMO) fading channels. With channel state information available at the transmitter, our focus is to maximize the minimum Euclidean distance among all candidates of SM symbols. We prove that the precoder design is a large-scale non-convex quadratically constrained quadratic program (QCQP) problem. However, the conventional methods, such as semi-definite relaxation and iterative concave-convex process, cannot tackle this challenging problem effectively or efficiently. To address this issue, we leverage augmented Lagrangian and dual ascent techniques, and transform the original large-scale non-convex QCQP problem into a sequence of subproblems. These subproblems can be solved in an iterative manner efficiently. Numerical results show that the proposed method can significantly improve the system error performance relative to the SM without precoding, and features extremely fast convergence rate with very low computational complexity.

Cheng, Q, Nguyen, D, Dutkiewicz, E & Mueck, MD 2018, 'Protecting Operational Information of Incumbent and Secondary Users in FCC Spectrum Access System', International Conference on Communications, IEEE, Kansas City, MO, USA.
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Both Federal Communications Commission (FCC) and European Telecommunications Standards Institute (ETSI) support dynamic spectrum access (DSA) as an enabling technology for spectrum sharing. To effectively realize DSA in practice, users (from both defense and civil sectors) are required to share their (radio) operational information. That risks exposing their security, privacy, and business plan to unintended agents. In this paper, taking FCC's spectrum access system (SAS) as a study case, we propose a privacy-preserving scheme for DSA by leveraging encryption and obfuscation methods (PSEO). To implement PSEO, we propose an interference calculation scheme that allows users to calculate interference budget without revealing their operation information (e.g., antenna height, transmit power, location...), referred to as blind interference calculation method (BICM). BICM also reduces the computing overhead of PSEO, compared with FCC's SAS by moving interference budgeting tasks to local users and calculating it in an offline manner. Extensive detailed analysis and simulations show that our proposed PSEO is able to better protect all users' operational privacy, guaranteeing efficient spectrum utilization with less online overhead, compared with state of the art approaches.

Cook, K & Canning, J 2018, '3D printed photonics INVITED', Asia Pacific Opt. Sensors, Auckland NZ.
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Recent progress in the field of 3D-printed photonic devices and their tremendous potential in sensing applications is reviewed. This truly disruptive technology has led to the realization of polymer optical fibres made from 3D-printed preforms, planar rib waveguides, lens arrays and prisms, all precursors for coming 3D printing of silica and other components.

Debabrata Karmokar, K & Jay Guo, Y 2018, 'Continuous Backward-to-Forward Beam-Scanning Conformal Leaky-Wave Antenna', Proceedings of the 2018 IEEE 7th Asia-Pacific Conference on Antennas and Propagation, APCAP 2018, pp. 72-73.
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© 2018 IEEE. A periodic substrate integrated waveguide (SIW) structure based conformal leaky-wave antenna (LWA) is presented. The LWA is capable of scanning its beam from near backfire, backward endfire, through the broadside to the forward direction. The-10-dB reflection coefficient bandwidth of the antenna is 7.428-10.47 GHz. The gain of the antenna is greater than 10 dBi throughout the beam scan range from-84° to +19°with a variation of source frequency from 7.3 to 10.3 GHz.

Diao, Y, Li, M, Sun, W, Wingleung, S, Cai, Y, Zhu, F & Yang, Y 2018, 'Safety Consideration for Emerging Wireless Technologies-Evaluations of Temperature Rise in Eyes for RF Radiations up to 10 GHz', International Symposium on Medical Information and Communication Technology, ISMICT.
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© 2018 IEEE. The study of temperature rise distribution in the human eye under plane electromagnetic wave exposure up to 10 GHz is presented in this paper. The effects of different frequencies and different blood perfusion rates of sclera to thermal calculations are investigated by finite difference method. The results reveal that the changes in the thermal parameter produce a maximum relative standard deviation of ~15% in the temperature rise in lens.

Ding, C, Sun, H, Guo, YJ & Ziolkowski, RW 2018, 'A general design and optimization method of tightly-coupled cross-dipoles for base station', IET Conference Publications.
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© 2018 Institution of Engineering and Technology.All Rights Reserved. This paper investigates the working mechanism of dual-polarized tightly-coupled cross-dipoles that are widely used in cellular base station applications. The effects of couplings between sub-dipoles on the performance indexes of concern are observed. A theory of considering this type of cross-dipole as an array is proposed and validated. The proposed theory explains why a stable radiation pattern can be achieved by this kind of structure. The array model can be used to guide the introduction and optimization of a simplified cross-dipole structure for base station application.

Dinh, H, Niyato, D, Wang, P, Domenico, AD & Strinati, EC 2018, 'Optimal Cross Slice Orchestration for 5G Mobile Services'.
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5G mobile networks encompass the capabilities of hosting a variety of services such as mobile social networks, multimedia delivery, healthcare, transportation, and public safety. Therefore, the major challenge in designing the 5G networks is how to support different types of users and applications with different quality-of-service requirements under a single physical network infrastructure. Recently, network slicing has been introduced as a promising solution to address this challenge. Network slicing allows programmable network instances which match the service requirements by using network virtualization technologies. However, how to efficiently allocate resources across network slices has not been well studied in the literature. Therefore, in this paper, we first introduce a model for orchestrating network slices based on the service requirements and available resources. Then, we propose a Markov decision process framework to formulate and determine the optimal policy that manages cross-slice admission control and resource allocation for the 5G networks. Through simulation results, we show that the proposed framework and solution are efficient not only in providing slice-as-a-service based on the service requirements, but also in maximizing the provider's revenue.

Dinh, H, Niyato, D, Wang, P, Wang, S, Nguyen, D & Dutkiewicz, E 2018, 'A Stochastic Programming Approach for Risk Management in Mobile Cloud Computing', IEEE Wireless Communications and Networking Conference, IEEE, Barcelona, Spain.
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The development of mobile cloud computing has brought many benefits to mobile users as well as cloud service providers. However, mobile cloud computing is facing some challenges, especially security-related problems due to the growing number of cyberattacks which can cause serious losses. In this paper, we propose a dynamic framework together with advanced risk management strategies to minimize losses caused by cyberattacks to a cloud service provider. In particular, this framework allows the cloud service provider to select appropriate security solutions, e.g., security software/hardware implementation and insurance policies, to deal with different types of attacks. Furthermore, the stochastic programming approach is adopted to minimize the expected total loss for the cloud service provider under its financial capability and uncertainty of attacks and their potential losses. Through numerical evaluation, we show that our approach is an effective tool in not only dealing with cyberattacks under uncertainty, but also minimizing the total loss for the cloud service provider given its available budget.

Dong, L, Niyato, D, Kim, DI & Hoang, DT 2017, 'A joint scheduling and content caching scheme for energy harvesting access points with multicast', 2017 IEEE Global Communications Conference, GLOBECOM 2017 - Proceedings, IEEE Global Communications Conference, Singapore, Singapore, pp. 1-6.
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© 2017 IEEE. In this work, we investigate a system where users are served by an access point that is equipped with energy harvesting and caching mechanism. Focusing on the design of an efficient content delivery scheduling, we propose a joint scheduling and caching scheme. The scheduling problem is formulated as a Markov decision process and solved by an on-line learning algorithm. To deal with large state space, we apply the linear approximation method to the state-Action value functions, which significantly reduces the memory space for storing the function values. In addition, the preference learning is incorporated to speed up the convergence when dealing with the requests from users that have obvious content preferences. Simulation results confirm that the proposed scheme outperforms the baseline scheme in terms of convergence and system throughput, especially when the personal preference is concentrated to one or two contents.

dos Santos, AP & Chaczko, Z 2018, 'Blockchain: Status-Quo, Enablers and Inhibitors', 2018 26th International Conference on Systems Engineering (ICSEng), International Conference on Systems Engineering, IEEE, Sydney, Australia.
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Dreyer, U, Di Renzo, AB, de Bastos, TP, da Silva, MJ, Pipa, D, Janeczko, C, Zamarreño, CR, Weber, G, Loyola, M, Martelli, G & Canning, J 2018, 'Wired Horses', Optics InfoBase Conference Papers, Advanced Photonics, Zurich, Switzerland.
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© 2018 The Author(s). Horses are empowered by using a specialized network of optical fiber sensors integrated to augmented reality technology which enhances their communication with the rider/owner during training, racing and possibly entire life.

Fan, X, He, X, Puthal, D, Chen, S, Xiang, C, Nanda, P & Rao, X 2018, 'CTOM: Collaborative Task Offloading Mechanism for Mobile Cloudlet Networks', International Conference on Communications, IEEE, Kansas City, MO, USA.
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Feng, J, Hasan Shehab, S, Yang, Y, Karmakar, NC & Gupta, S 2018, 'A Design and Implementation of an Ambulatory Electrocardiogram (ECG) Acquisition Circuit for Emergency Application', 2018 12th International Symposium on Medical Information and Communication Technology (ISMICT), 2018 12th International Symposium on Medical Information and Communication Technology (ISMICT), IEEE.
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Gamal, M, Abolhasan, M, Lipman, J, Liu, RP & Ni, W 2018, 'Multi Objective Resource Optimisation for Network Function Virtualisation Requests', 2018 26TH INTERNATIONAL CONFERENCE ON SYSTEMS ENGINEERING (ICSENG 2018), 26th International Conference on Systems Engineering (ICSEng), IEEE, Univ Technol Sydney, Sydney, AUSTRALIA.

Gao, X, Du, J, Zhang, T & Guo, YJ 2018, '0.34-THz High-Temperature Superconducting Josephson-Junction Mixer with Superior Noise and Conversion Performance', International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz, International Conference on Infrared, Millimeter, and Terahertz Waves, IEEE, Nagoya, Japan.
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© 2018 IEEE. We present, in this work, a new thin-film antenna-coupled high-temperature superconducting (HTS) Josephson-junction terahertz (THz) mixer that demonstrates superior performance at frequencies around 0.34 THz. A novel dual-meander-slot thin-film antenna is designed to significantly improve the antenna-junction impedance matching and thus more efficient coupling of the THz signal power. Theoretical and experimental investigations are carried out to evaluate the mixer performance. This mixer can be applied to the sensitive THz wireless receivers.

Gao, X, Zhang, T, Du, J & Guo, YJ 2018, '300-GHz Dual-Beam Frequency-Selective On-Chip Antenna for High-T-c Superconducting Receivers', 2018 INTERNATIONAL SYMPOSIUM ON ANTENNAS AND PROPAGATION (ISAP), International Symposium on Antennas and Propagation (ISAP), IEEE, Busan, SOUTH KOREA.

Gong, Y, Li, Z, Zhang, J, Liu, W, Zheng, Y & Kirsch, C 2018, 'Network-wide Crowd Flow Prediction of Sydney Trains via customized Online Non-negative Matrix Factorization', The 27th ACM International Conference on Information and Knowledge Management, Turin, Italy.
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Gorski, T, Bednarski, J & Chaczko, Z 2018, 'Blockchain-based renewable energy exchange management system', 2018 26th International Conference on Systems Engineering (ICSEng), International Conference on Systems Engineering, IEEE, Sydney, Australia, Australia.
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Guo, D, Zhao, W, Cui, Y, Wang, Z, Chen, S & Zhang, J 2018, 'Siamese network based features fusion for adaptive visual tracking', Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics), pp. 759-771.
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© Springer Nature Switzerland AG 2018. Visual object tracking is a popular but challenging problem in computer vision. The main challenge is the lack of priori knowledge of the tracking target, which may be only supervised of a bounding box given in the first frame. Besides, the tracking suffers from many influences as scale variations, deformations, partial occlusions and motion blur, etc. To solve such a challenging problem, a suitable tracking framework is demanded to adopt different tracking scenes. This paper presents a novel approach for robust visual object tracking by multiple features fusion in the Siamese Network. Hand-crafted appearance features and CNN features are combined to mutually compensate for their shortages and enhance the advantages. The proposed network is processed as follows. Firstly, different features are extracted from the tracking frames. Secondly, the extracted features are employed via Correlation Filter respectively to learn corresponding templates, which are used to generate response maps respectively. And finally, the multiple response maps are fused to get a better response map, which can help to locate the target location more accurately. Comprehensive experiments are conducted on three benchmarks: Temple-Color, OTB50 and UAV123. Experimental results demonstrate that the proposed approach achieves state-of-the-art performance on these benchmarks.

Ha, M, Pham, T, Nguyen, D & Dutkiewicz, E 2018, 'Non-Laboratory-Based Risk Factors for Automated Heart Disease Detection', International Symposium on Medical Information and Communication Technology (ISMICT), Sydney, Australia.
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Haider, N, Ali, A, He, Y & Dutkiewicz, E 2018, 'Performance Analysis of Full Duplex D2D in Opportunistic Spectrum Access', ISCIT 2018 - 18th International Symposium on Communication and Information Technology, pp. 383-388.
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© 2018 IEEE. Opportunistic Spectrum Access (OSA) allows an efficient use of spectrum based on share-it or use-it principle and can be a viable solution for the challenging problem of spectrum scarcity. Emerging systems have been proposed for OSA, where primary users (PU) have guaranteed interference protection from secondary users (SU). The potential of Full Duplex (FD) and Device-To-device (D2D) technologies in 5G has proven to be promising for increasing data rates and network capacity. In this article using stochastic geometry and random graphs, we model and assess the D2D operations in full Duplex/half Duplex mode for SUs, while protecting the PU's transmission by defining the exclusion zone (EZ). Depending on the location and transmit power of D2D users, the induced aggregate interference should not violate the interference threshold for EZ of PUs. For this, we characterize the interference from D2D links and derive the probability for successful D2D users for half-duplex and full duplex modes. Analyses is further supported by extensive simulations results.

Han, Z 2018, 'Performance Analysis and Application of Mobile Blockchain', 2018 International Conference on Computing, Networking and Communications, ICNC 2018, Maui, HI, USA, pp. 642-646.
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© 2018 IEEE. Mobile security has become more and more important due to the boom of mobile commerce (m-commerce). However, the development of m-commerce is facing many challenges regarding data security problems. Recently, blockchain has been introduced as an effective security solution deployed successfully in many applications in practice, such as, Bitcoin, cloud computing, and Internet-of-Things. In this paper, we introduce a new m-commerce application using blockchain technology, namely, MobiChain, to secure transactions in the m-commerce. Especially, in the MobiChain application, the mining processes can be executed efficiently on mobile devices using our proposed Android core module. Through real experiments, we evaluate the performance of the proposed model and show that blockchain will be an efficient security solution for future m-commerce.

Hoang, DT, Niyato, D & Wang, P 2018, 'Optimal cost-based cyber insurance policy management for mobile services', IEEE Vehicular Technology Conference, pp. 1-5.
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© 2017 IEEE. This paper introduces a cyber insurance policy management for the mobile networks in which if a mobile user agrees to purchase an insurance policy from an insurer, the loss of the mobile user, i.e., the insured, will be covered by the insurance policy when the risks happen. To protect mobile users from cyber attacks, the insurer can deploy security protection solutions, e.g., anti-virus software or personal firewall, to the insureds, thereby reducing the risks for mobile users. However, when the solutions are deployed, they will incur a certain cost to the insurer. Therefore, we propose a stochastic optimization based on the reserve state of the insurer and the number of active mobile users to determine whether the protection solutions should be deployed or not to maximize the revenue for the insurer. The performance evaluation reveals that the optimal policy can achieve significantly higher revenue than those of baseline schemes for the insurer. Alternatively, the coalitional game is studied to share the reward among the insurers, and we show that the insurers can gain higher individual rewards through the cooperation.

Huang, D-Y, Zhao, S, Schuller, BW, Yao, H, Tao, J, Xu, M, Xie, L, Huang, Q & Yang, J 2018, 'ASMMC-MMAC 2018', 2018 ACM Multimedia Conference on Multimedia Conference - MM '18, 2018 ACM Multimedia Conference, ACM Press.
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Huang, H, Xu, J, Zhang, J, Wu, Q & Kirsch, C 2018, 'Railway Infrastructure Defects Recognition using Fine-grained Deep Convolutional Neural Networks', 2018 Digital Image Computing: Techniques and Applications (DICTA), Digital Image Computing: Techniques and Applications, IEEE, Canberra, Australia.
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Jauregi Unanue, I, Garmendia Arratibel, L, Zare Borzeshi, E & Piccardi, M 2018, 'English-Basque Statistical and Neural Machine Translation', Language Resources and Evaluation Conference, Miyazaki, Japan, pp. 880-885.
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Jauregi Unanue, I, Zare Borzeshi, E & Piccardi, M 2018, 'A Shared Attention Mechanism for Interpretation of Neural Automatic Post-Editing Systems', Workshop on Neural Machine Translation and Generation, Melbourne, Australia, pp. 11-17.
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Automatic post-editing (APE) systems aim to correct the systematic errors made by machine translators. In this paper, we propose a neural APE system that encodes the source (src) and machine translated (mt) sentences with two separate encoders, but leverages a shared attention mechanism to better understand how the two inputs contribute to the generation of the post-edited (pe) sentences. Our empirical observations have showed that when the mt is incorrect, the attention shifts weight toward tokens in the src sentence to properly edit the incorrect translation. The model has been trained and evaluated on the official data from the WMT16 and WMT17 APE IT domain English-German shared tasks. Additionally, we have used the extra 500K artificial data provided by the shared task. Our system has been able to reproduce the accuracies of systems trained with the same data, while at the same time providing better interpretability.

Kempegowda, SM & Chaczko, Z 2018, 'Essential Skill of Enterprise Architect Practitioners for Digital Era', 2018 26th International Conference on Systems Engineering (ICSEng), International Conference on Systems Engineering, IEEE, Sydney, Australia.
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Kempegowda, SM & Chaczko, Z 2018, 'Industry 4.0 Complemented with EA Approach: A Proposal for Digital Transformation Success', 2018 26th International Conference on Systems Engineering (ICSEng), International Conference on Systems Engineering, IEEE, Sydney, Australia.
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Kempegowda, SM & Chaczko, Z 2018, 'The optimum number of Principles ideal for Enterprise Architecture practice', 2018 26th International Conference on Systems Engineering (ICSEng), International Conference on Systems Engineering, IEEE, Sydney, Australia.
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Khan, AA, Abolhasan, M & Ni, W 2018, '5G next generation VANETs using SDN and fog computing framework', CCNC 2018 - 2018 15th IEEE Annual Consumer Communications and Networking Conference, IEEE Annual Consumer Communications & Networking Conference, IEEE, Las Vegas, NV, USA, pp. 1-6.
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© 2018 IEEE. The growth of technical revolution towards 5G Next generation networks is expected to meet various communication requirements of future Intelligent Transportation Systems (ITS). Motivated by the consumer needs for variety of ITS applications, bandwidth, high speed and ubiquity, researches are currently exploring different network architectures and techniques, which could be employed in Next generation ITS. To provide flexible network management, control and high resource utilization in Vehicular Ad-hoc Networks (VANETs) on large scale, a new hierarchical 5G Next generation VANET architecture is proposed. The key idea of this holistic architecture is to integrate the centralization and flexibility of Software Defined Networking (SDN) and Cloud-RAN (CRAN), with 5G communication technologies, to effectively allocate resources with a global view. Moreover, a fog computing framework (comprising of zones and clusters) has been proposed at the edge, to avoid frequent handovers between vehicles and RSUs. The transmission delay, throughput and control overhead on controller are analyzed and compared with other architectures. Simulation results indicate reduced transmission delay and minimized control overhead on controllers. Moreover, the throughput of proposed system is also improved.

Klempous, R, Berenguel, M, Chaczko, Z, Rozenblit, JW & Nikodem, J 2018, 'Vitae Summary: Contributions of Prof. Klempous', INES 2018 - IEEE 22nd International Conference on Intelligent Engineering Systems, Proceedings, pp. 000011-000012.
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© 2018 IEEE. This brief paper presents an overview of the main achievements of Prof. R. Klempous in his collaborations with the Automatic Control, Robotics an Mechatronics research group of CIESOL Center at Universidad de Almeria and the Platforma Solar de Almería, Department of Electrical and Computer Engineering, University of Arizona, Tucson and University of Technology, Sydney.

Lancry, M, Cook, K, Pallare´s-Aldeiturriaga, D, Lopez-Higuera, JM, Poumellec, B & Canning, J 2018, 'Raman spectroscopic study of Bragg gratings regeneration', Optics InfoBase Conference Papers.
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© 2018 The Author(s). Fibre Bragg grating regeneration involves, at its simplest, the annealing and resurrection of a seed FBG through thermal annealing. Micro-Raman spectroscopy provides evidence that inscribing the seed structure has changed the thermal history of the glass so that whilst the annealing is identical in all areas, the local glass relaxation is different in the UV irradiated regions. Notably, there is a significant decrease of the D1 and D2 defects bands within the core and the inner cladding of regenerated FBG revealing the complex nature of this two- or three materials system.

Le, AT, Nan, Y, Tran, LC, Huang, X, Guo, YJ & Vardaxoglou, JCY 2018, 'Analog Least Mean Square Loop for Self-Interference Cancellation in Generalized Continuous Wave SAR', In Proceedings of the IEEE 88th Vehicular Technology Conference, IEEE 88th Vehicular Technology Conference, Chicago, US.
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Li, H, Wang, Q, Huang, X & Guo, YJ 2018, 'Matrix Normalization Based ZF Hybrid Precoded Multi-User MIMO mmWave Systems with Massive Array', 2018 IEEE 88th Vehicular Technology Conference, Chicargo, USA.
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Li, M, Cai, YX, Bautista, MG, Yang, Y & Zhu, X 2018, 'Broadband on-chip bandpass filter using ring resonator with capacitive loading', 2018 Australian Microwave Symposium, AMS 2018 - Conference Proceedings, Australian Microwave Symposium, Brisbane, QLD, Australia, pp. 55-56.
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© 2018 IEEE. Design of a broadband on-chip bandpass filter (BPF) using grounded ring resonator with capacitive loading technique is presented in this paper. To prove the concept, a standard 0.13-μm (Bi)-CMOS technology is selected for implementation. To understand how to effectively optimize the designed BPF, parametric studies against some critical parameters are given by means of EM simulation. Finally, the implemented filter is fabricated. The measured results show that the BPF has a center frequency at 33 GHz with a bandwidth of 42.4%. The minimum insertion loss is 2.6 dB, while the stopband rejection is maintained to be better than 20 dB beyond 58 GHz. The chip, excluding the pads, is very compact at only 0.03 mm2 (0.11 × 0.28 mm2).

Li, Z, Yao, L, Nie, P, Zhang, D & Xu, M 2018, 'Multi-rate Gated Recurrent Convolutional Networks for Video-Based Pedestrian Re-Identification', The Thirty-Second AAAI Conference on Artificial Intelligence (AAAI-18), The 32nd AAAI Conference on Artifical Intelligence, New Orleans, Lousiana, USA.

Li, Z, Zhang, J, Wu, Q & Kirsch, C 2018, 'Field-regularised factorization machines for mining the maintenance logs of equipment', Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics), pp. 172-183.
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© Springer Nature Switzerland AG 2018. Failure prediction is very important for railway infrastructure. Traditionally, data from various sensors are collected for this task. Value of maintenance logs is often neglected. Maintenance records of equipment usually indicate equipment status. They could be valuable for prediction of equipment faults. In this paper, we propose Field-regularised Factorization Machines (FrFMs) to predict failures of railway points with maintenance logs. Factorization Machine (FM) and its variants are state-of-the-art algorithms designed for sparse data. They are widely used in click-through rate prediction and recommendation systems. Categorical variables are converted to binary features through one-hot encoding and then fed into these models. However, field information is ignored in this process. We propose Field-regularised Factorization Machines to incorporate such valuable information. Experiments on data set from railway maintenance logs and another public data set show the effectiveness of our methods.

Liao, Q, Xu, M, Wang, D & Holewa, H 2018, 'FINE-GRAINED CATEGORIZATION BY DEEP PART-COLLABORATION CONVOLUTION NET', 2018 INTERNATIONAL CONFERENCE ON DIGITAL IMAGE COMPUTING: TECHNIQUES AND APPLICATIONS (DICTA), International Conference on Digital Image Computing - Techniques and Applications (DICTA), IEEE, Canberra, AUSTRALIA, pp. 667-674.

Lil, M, Lin, JY, Yang, Y, Zhu, X & Wong, SW 2018, 'A New Approach of Individually Control of Shorting Posts for Pattern Reconfigurable Antenna Designs', 2018 IEEE International Conference on Computational Electromagnetics, ICCEM 2018, International Conference on Computational Electromagnetics, IEEE, Chengdu, China.
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© 2018 IEEE. This paper presents a recently proposed novel approach for pattern reconfigurable antenna designs. Individually associating a shorting post with an RF switch, the shorting post can be simply connected to the ground by turning the switch on or disconnected to the ground by turning the switch off. This approach has been successfully validated through two recently reported designs, for the implementations of transverse magnetic TM mode reconfiguration and 360° beam-steering.

Lin, JY, Li, MZ, Wong, SW, Yang, Y & Zhu, X 2018, 'A cavity triple-mode filter with excitation of L-shape model', 2018 Australian Microwave Symposium, AMS 2018 - Conference Proceedings, Australian Microwave Symposium, IEEE, Brisbane, Australia, pp. 17-18.
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© 2018 IEEE. A triple-mode cavity filter with narrow passband realized in a single rectangular metal cavity without any tune crews, coupling apertures, iris, and corner cuts is proposed in this paper, while three resonant modes are classified as a TM mode and a pair of TE modes, which are excited by two metal probes in one single cavity. At both the upper and lower stop-bands, two transmission zeros are created to achieve a considerable out-of-band suppression. To prove the concept, a prototype is fabricated by using the silver plated aluminum technology demonstrating a measured fractional bandwidth of 3.6% at the center frequency of 2.53 GHz. The measured and simulated results are presented in good agreement.

Lin, W & Ziolkowski, RW 2018, 'Dual-Functional Electrically Small Huygens Antenna System', 2018 INTERNATIONAL SYMPOSIUM ON ANTENNAS AND PROPAGATION (ISAP), International Symposium on Antennas and Propagation (ISAP), IEEE, Busan, SOUTH KOREA.
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Lin, W & Ziolkowski, RW 2018, 'Eletrically-Small Rectenna with Huygens Radiation Pattern for Wireless Power Transfer Applications', 2018 IEEE ANTENNAS AND PROPAGATION SOCIETY INTERNATIONAL SYMPOSIUM ON ANTENNAS AND PROPAGATION & USNC/URSI NATIONAL RADIO SCIENCE MEETING, IEEE-Antennas-and-Propagation-Society International Symposium on Antennas and Propagation / USNC/URSI National Radio Science Meeting, IEEE, Boston, MA, pp. 311-312.
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Lin, W, Ziolkowski, RW & Tang, MC 2018, 'Circularly polarized electrically small antennas for emerging wireless applications', IET Conference Publications.
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© Institution of Engineering and Technology.All Rights Reserved. This paper introduces three circularly-polarized (CP) electrically small antennas for emerging wireless applications including wireless power transfer (WPT), Internet-of-Things (IoT), and Device-to-Device (D2D) communications in future fifth generation (5G) systems. First, an electrically small Huygens CP (HCP) antenna operating at L-band frequencies is presented that is facilitated by two near-field resonant parasitic (NFRP) elements, a crossed Egyptian axe dipole (EAD) pair and a crossed capacitively loaded loop (CLL) pair. The HCP antenna is electrically small (ka = 0.73), low profile (~ 0.04°0), and has decent cardioid-shaped radiation patterns with a broad half power beamwidth (>120°). It is attractive for many WPT and body-centric wireless sensor network applications. Second, with the rapid development of 5G wireless networks, a corresponding 28 GHz electrically small HCP antenna is reported. The overall size of this antenna is only p (1.5)2 × 1 ˜ 7 mm3 (ka = 0.94), which can be readily integrated into the various compact platforms anticipated for 5G IoT devices. Third, unlike the above two antennas that radiate uni-directional patterns, a compact 28 GHz omni-directional CP (OCP) antenna is presented for D2D communications in future 5G systems. It is electrically small (ka = 0.95), easy to fabricate, and its performance characteristics cover the entire FCC-specified 5G, 27.5 to 28.35 GHz band.

Lin, W, Ziolkowski, RW & Wong, H 2018, 'Pattern reconfigurable techniques for LP and CP antennas with the broadside and conical beams', IET Conference Publications.
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© Institution of Engineering and Technology.All Rights Reserved. This paper presents two pattern reconfigurable techniques to realize linear (LP) and circular (CP) broadside and conical-beam switchable radiation patterns from a single antenna. First, a wideband monopolar patch and a L-probe fed patch were organically integrated together to achieve a wideband (2.25 to 2.85 GHz) broadside and conical-beam pattern reconfigurable system that radiates LP radiation. Radiation coverage and wireless channel capacity were improved significantly making the reported LP antenna a good candidate as a ceiling mounted antenna for indoor wireless communications. On the other hand, a circularly-polarized (CP) broadside and conical-beam reconfigurable antenna would be preferred for satellite communications. To realize it, we successfully excited both the TM11 and TM21 modes on a circular patch with an annular slot antenna. A reconfigurable feeding network was designed to provide the correct excitations for these two modes. CP switchable broadside and conical radiated beams were realized within the same overlapping frequency ranges from 2.45 to 2.65 GHz. Both the LP and CP antennas were fabricated and tested. Experimental results show good agreement with their simulated performance characteristics. Very good radiation performance was obtained.

Luo, X, Su, Z, Guo, J, Zhang, G & He, X 2018, 'Trusted guidance pyramid network for human parsing', MM 2018 - Proceedings of the 2018 ACM Multimedia Conference, Seoul, pp. 654-662.
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© 2018 Association for Computing Machinery. Human parsing has a wide range of applications. However, none of the existing methods can productively solve the issue of label parsing fragmentation due to confused and complicated annotations. In this paper, we propose a novel Trusted Guidance Pyramid Network (TGPNet) to address this limitation. Based on a pyramid architecture, we design a Pyramid Residual Pooling (PRP) module setting at the end of a bottom-up approach to capture both global and local level context. In the top-down approach, we propose a Trusted Guidance Multi-scale Supervision (TGMS) that efficiently integrates and supervises multi-scale contextual information. Furthermore, we present a simple yet powerful Trusted Guidance Framework (TGF) which imposes global-level semantics into parsing results directly without extra ground truth labels in model training. Extensive experiments on two public human parsing benchmarks well demonstrate that our TGPNet has a strong ability in solving label parsing fragmentation problem and has an obtained improvement than other methods.

Luo, Z, Xu, KD, Cai, Y & Liu, Y 2018, 'Fourth-Order Bandpass Filter Using Dual-Mode Ring Resonator and Parallel-Coupled Lines', 2018 IEEE International Conference on Computational Electromagnetics, ICCEM 2018.
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© 2018 IEEE. A fourth-order bandpass filter using dual-mode ring resonator and parallel-coupled lines loaded with half-wavelength open stubs is presented in this paper. Six transmission zeros (TZs) and four transmission poles (TPs) from 0 to 2f0(f0 denotes center frequency of the filter passband) can be achieved with the help of two open stubs and open coupled lines, where two TZs are generated by the loaded two open stubs. Finally, a verified physical layout of the proposed filter is designed and simulated with good frequency selectivity, whose ADS and HFSS simulations are in good agreement.

Makhdoom, I, Abolhasan, M & Ni, W 2018, 'Blockchain for IoT: The Challenges and aWay Forward', SciTePress, Proceedings of the 15th International Joint Conference on e-Business and Telecommunications - Volume 2: SECRYPT, INSTICC, Porto, Portugal.
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Bitcoin has revolutionized the decentralized payment system by excluding the need for a trusted third party, reducing the transaction (TX) fee and time involved in TX confirmation as compared to a conventional banking system. The underlying technology of Bitcoin is Blockchain, which was initially designed for financial TXs only. However, due to its decentralized architecture, fault tolerance and cryptographic security benefits such as user anonymity, data integrity and authentication, researchers and security analysts around the world are focusing on the Blockchain to resolve security and privacy issues of IoT. But at the same time, default limitations of Blockchain, such as latency in transaction confirmation, scalability concerning Blockchain size and network expansion, lack of IoT-centric transaction validation rules, the absence of IoT-focused consensus protocols and insecure device integration are required to be addressed before it can be used securely and efficiently in an IoT environment. Therefore, in this paper we analyze some of the existing consensus protocols used in various Blockchain-based applications, with a focus on investigating significant limitations in TX (Transaction) validation and consensus mechanism that make them inappropriate to be implemented in Blockchain-based IoT systems. We also propose a way forward to address these issues.

Malik, N, Nanda, P, Arora, A, He, X & Puthal, D 2018, 'Blockchain Based Secured Identity Authentication and Expeditious Revocation Framework for vehicular Networks', IEEE Computer Society, The 17th IEEE International Conference On Trust, Security And Privacy In Computing And Communications (IEEE TrustCom-18), New York.
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Mehar, AM, Gill, AQ & Matawie, K 2018, 'Analytical Model for Residential Predicting Energy Consumption', International Conference on Business Informatics, Vienna, Austria..

More, FJ & Chaczko, Z 2018, 'Non-invasive Methods in the Detection of Coronary Artery Disease', 2018 26th International Conference on Systems Engineering (ICSEng), International Conference on Systems Engineering, IEEE, Sydney, Australia.
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Nanda, A, Nanda, P, He, X, Puthal, D & Jamdagni, A 2018, 'A Novel Hybrid Authentication Model for Geo Location Oriented Routing in Dynamic Wireless Mesh Networks', Proceedings of the 51st Hawaii International Conference on System Sciences 2018, International Conference on System Sciences, Hawaii, USA, pp. 5532-5541.
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Authentication is an essential part of any network and plays a pivotal role in ensuring the security of a network by preventing unauthorised devices/users access to the network. As dynamic wireless mesh networks are evolving and being accepted in various fields, there is a strong need to improve the security of the network. It’s features like self-organizing and self-healing make it great but get undermined when rigid authentication schemes are used. We propose a hybrid authentication scheme for such dynamic mesh networks under three specified scenarios; full authentication, quick authentication and new node authentication. The proposed schemes are applied on our previous works on dynamic mesh routing protocol, Geo location Oriented Routing Protocol (GLOR Simulation results show our proposed scheme is efficient in terms of resource utilization as well as defending against security threats.

Nguyen, H, Dinh, H, Nguyen, D, Dutkiewicz, E, Niyato, D & Wang, P 2018, 'Reinforcement Learning Approach for RF-Powered Cognitive Radio Network with Ambient Backscatter', IEEE Global Communications Conference, UAE.
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Nguyen, K, Dinh, H, Niyato, D, Wang, P, Nguyen, D & Dutkiewicz, E 2018, 'Cyberattack Detection in Mobile Cloud Computing: A Deep Learning Approach', IEEE Wireless Communications and Networking Conference (WCNC), Barcelona, Spain.
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Nguyen, T, Nguyen, H, Dinh, H, Nguyen, D & Dutkiewicz, E 2018, 'Offloading Energy Efficiency with Delay Constraint for Cooperative Mobile Edge Computing Networks', IEEE Global Communications Conference, UAE.
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Ni, Z, Zhang, JA, Yang, K, Gao, F & Gao, Z 2018, 'Codebook Based Minimum Subspace Distortion Hybrid Precoding for Millimeter Wave Systems', Globecom 2018, Abu Dhabi, UAE.
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Pham, T, Nguyen, D, Dutkiewicz, E, McEwan, A, Leong, P & Fuglevand, A 2018, 'Feature Analysis for Discrimination of Motor Unit Action Potentials', International Symposium on Medical Information and Communication Technology, Sydney, Australia.
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Poostchi, H & Piccardi, M 2018, 'Cluster Labeling by Word Embeddings and WordNet’s Hypernymy', https://www.aclweb.org/anthology/U18-1, Annual Workshop of The Australasian Language Technology Association, Dunedin, New Zealand.
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Cluster labeling is the assignment of representative labels to clusters of documents or words. Once assigned, the labels can play an important role in applications such as navigation, search and document classification. However, finding appropriately descriptive labels is still a challenging task. In this paper, we propose various approaches for assigning labels to word clusters by leveraging word embeddings and the synonymy and hypernymy relations in the WordNet lexical ontology. Experiments carried out using the WebAP document dataset have shown that one of the approaches stand out in the comparison and is capable of selecting labels that are reasonably aligned with those chosen by a pool of four human annotators.

Poostchi, H, Zare Borzeshi, E & Piccardi, M 2018, 'BiLSTM-CRF for Persian Named-Entity RecognitionArmanPersoNERCorpus: the First Entity-Annotated Persian Dataset', Language Resources and Evaluation Conference, Miyazaki, Japan, pp. 4427-4431.
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Qin, PY, Guo, YJ & Ji, LY 2018, 'Reconfigurable partially reflective surface antennas', 2017 IEEE 6th Asia-Pacific Conference on Antennas and Propagation, APCAP 2017 - Proceeding, pp. 1-3.
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© 2017 IEEE. In this paper, the research of reconfigurable partially reflective surface (PRS) antennas at University of Technology Sydney (UTS) is introduced. Two reconfigurable PRS antennas are described that can achieve beam scanning and wideband polarization switch, respectively.

Rafiei, A, Abolhasan, M, Franklin, DR, Safaei, F, Smith, S & Ni, W 2017, 'Cooperative recovery of coverage holes in WSNs via disjoint spanning trees', 2017, 11th International Conference on Signal Processing and Communication Systems, ICSPCS 2017 - Proceedings, International Conference on Signal Processing and Communication Systems, IEEE, Gold Coast, QLD, Australia, pp. 1-10.
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© 2017 IEEE. Large scale coverage holes (CHs) resulting from correlated node failures, can significantly degrade quality of service and also jeopardise the integrity of WSNs. In the absence of centralised control, the distributed relocation of deployed nodes becomes a promising solution especially in harsh and hostile environments. In this paper, a distributed method is proposed that enables a network to partially or entirely repair itself through a collection of distributed movements of disjoint spanned trees (DS-Trees) towards the CHs. DS-Trees are spanned based on the nodes distances from the CHs, which are autonomously perceived by the nodes and their one-hop neighbours. DS-Trees around the CHs are spanned in a downstream style outwards from the holes, as nodes select their parents based on the minimum distance to the CH from their neighbours; nodes then decide whether or not to follow the movements of their DS-Trees parents. To examine the efficiency of the proposed model, its performance is compared with two Voronoi-based and one force-based node relocation algorithms. Results show that the proposed DS-Tree model either outperforms or matches the alternative approaches across a wide range of scenarios.

Ranglund, OJ, Haave, H, Venemyr, GO, Vold, T & Braun, R 2018, 'Gaming and scenario building: A student active approach to learning', Proceedings of the European Conference on Games-based Learning, pp. 526-531.
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© 2018, Dechema e.V. All rights reserved. Students like to learn from gaming if the game has a learning objective they can recognize. In this paper we present research done at a course in a Bachelor in Crisis Management and Communication at The Inland Norway University of Applied Sciences. The course consists of several two-day seminars. The assignment was handed out at the first seminar. The objective of the assignment was to develop a playable scenario for one of three platforms; Rayvn, HoloLens and Virtual Battle Space3-platform (VBS3). On the VBS3-platform from Bohemia Interactive Solutions, a town is programmed with houses, vehicles, avatars, hospitals, and a number of other features. The town is called “Lyngvik”, and all bad things happen here; fires, landslides, explosions, to mention a few. Rayvn is an incident management tool. This text based tool was interesting to test out as a tool also for the simulating/gaming. HoloLens from Microsoft was maybe the most spectacular tool to test. The 3D view and possibilities this tool offered as a tool for executing a crisis management situation was highly interesting. The students were offered advising sessions to make sure that the scenarios were playable for the tools chosen. Our data are collected from researcher’s observations, and interviews with the students. These qualitative ways of collecting data during the two-day gaming session, gave us valuable insight into how this way of offering education provided the students with a safe and fun arena to learn more from. The preliminary results have been very positive. Even if the students were hesitant when receiving the assignment, the engagement they showed when gaming and simulating, were unmistakably. Technical issues with the VBS3-platform sometimes broke flow as the game needed restarting. Also, there were students that were unfamiliar with how to move avatars and vehicles. They learned this during the session. These are issues we need to take into account, ...

Seifollahi, S, Piccardi, M & Zare Borzeshi, E 2017, 'A semi-supervised hidden Markov topic model based on prior knowledge', Data Mining, The 15th Australasian Data Mining Conference, Springer, Melbourne, VIC, Australia,, pp. 265-276.
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A topic model is an unsupervised model to automatically discover the topics discussed in a collection of documents. Most of the existing topic models only use bag-of-words representations or single-word distributions and do not consider relations between words in the model. As a consequence, these models may generate topics which are not in good agreement with human-judged topic coherence. To mitigate this issue, we present a topic model which employs topically-related knowledge from prior topics and words’ co-occurrence/relations in the collection. To incorporate the prior knowledge, we leverage a two-staged semi-supervised Markov topic model. In the first stage, we estimate a transition matrix and a low-dimensional vocabulary for the final topic model. In the second stage, we produce the final topic model where the topic assignment is performed following a Markov chain process. Experiments on real text documents from a major compensation agency demonstrate improvements of both the PMI score measure and the topic coherence.

Shariati Moghadam, N, Chehrazad, S, Aghdasi, HS & Abolhasan, M 2018, 'Addressing coverage problem in wireless sensor networks based on evolutionary algorithms'.

Shen, J, Wang, Y & Zhang, J 2018, 'Memory optimized Deep Dense Network for Image Super-resolution'.
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Shen, J, Zhang, J & Wang, Y 2018, 'Deep Bi-Dense Networks for Image Super-Resolution', Digital Image Computing: Techniques and Applications, Canberra.
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Shi, L, Cai, K, Yang, T & Wang, T 2018, 'Linear network coded wireless caching', 2018 IEEE International Conference on Communications Workshops, ICC Workshops 2018 - Proceedings, pp. 1-6.
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© 2018 IEEE. This paper studies a K × M multiple-input multiple-output (MIMO) wireless caching that consists of a library, K base stations (BSs), and Mellintrf users, where each BS and user are equipped with NT and NR antennas respectively. Consider that each BS has a local cache that can prefetch some popular data requested by users from the library. We propose a linear network coding (NC) assisted wireless caching, considering the finite cache size and the variability of the user requests. In the cache placement phase, we design a joint NC caching function at K BSs to store linear combinations of messages from the library. In the content delivery phase, each user can successfully decode its requested messages by the receiver shaping and reverse NC operation. Our analytical results verify that, without any shared caching messages at different BSs, the proposed caching scheme is compatible with distinct user requests. In particular, for a 2×2 MIMO wireless caching network, the proposed caching scheme can achieve a higher total degree of freedom (DoF) of min(2NT, 2NR)-1 while consuming a smaller cache size, compared with the existing caching scheme.

Shi, T, Tang, MC & Ziolkowski, RW 2018, 'The Design of a Compact, Wide Bandwidth, Non-Foster-Based Substrate Integrated Waveguide Filter', Proceedings of the 2018 IEEE 7th Asia-Pacific Conference on Antennas and Propagation, APCAP 2018, pp. 54-56.
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© 2018 IEEE. A compact, wideband, half-mode substrate integrated waveguide (HM-SIW) filter with internal non-Foster element is demonstrated. First, its passive version is simulated and measured. Next, by integrating an ideal tunable capacitor at the end of the central stub of the HM-SIW resonator, the frequency-agile characteristic of the tunable HM-SIW filter is investigated. Finally, a negative impedance converter (NIC) is developed to replace this tunable capacitor to design a new nonFoster filter. The non-Foster-based HM-SIW filter was realized. Its measured results indicate that it has an operational fractional bandwidth of 10.8% and an electrical size 0.118 × 0.292 λ g 2, which is a 3.93 times bandwidth increase and a 12% electrical size reduction compared to its passive, fixed capacitance version.

Shi, Z, Xu, M, Pan, Q, Yan, B & Zhang, H 2018, 'LSTM-based Flight Trajectory Prediction', International Joint Conference on Neural Networks, Rio de Janeiro, Brazil.
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Shi, Z, Zhang, JA, Xu, Y & Fang, G 2018, 'Human Activity Recognition Using Deep Learning Networks with Enhanced Channel State information', Abu dabhi, UAE.
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Silva, MLD, Martelli, C & Canning, J 1970, 'Refractive Index Measurement using Diffraction in Photonic Crystal Fibers', Latin America Optics and Photonics Conference, Latin America Optics and Photonics Conference, OSA, Lima, Peru.
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Simorangkir, RBVB, Feng, S, Sayem, AS, Esselle, KP & Yang, Y 2018, 'PDMS-Embedded Conductive Fabric: A Simple Solution for Fabricating PDMS-Based Wearable Antennas with Robust Performance', International Symposium on Medical Information and Communication Technology, ISMICT.
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© 2018 IEEE. A new and simple fabrication method to realize robust flexible wearable antennas by combining conductive fabric and polydimethylsiloxane (PDMS) is proposed. The conductive fabric acts as the conductive part of the antenna, while PDMS acts as the substrate as well as the encapsulation layers. The method takes advantage of the porous structure of the conductive fabric and the initial liquid form of PDMS to attain a significantly strong integration between the two, leading to a robust PDMS-based wearable antenna. A number of patch antennas have been designed, fabricated, and tested to validate the proposed concept and the results are presented, showing robust performance. The fabricated prototypes have a resonance frequency approximately at 2.46 GHz with a 10 dB return-loss bandwidth ranging from 3.3 to 5.7%.

Simorangkir, RBVB, Li, M, Yang, Y, Xu, K, Esselle, K & Dutkiewicz, E 2018, '360-degree polarization scanning with the diversity of boresight and conical patterns switching', IET Conference Publications, European Conference on Antennas and Propagation, London, UK.
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© 2018 Institution of Engineering and Technology.All Rights Reserved. A novel reconfigurable antenna with the capability of 360-degree polarization scanning and the diversity of boresight and conical radiation patterns switching is presented in this paper. Each shorting-post is connected and controlled by a PIN diode to achieve the desired distribution of electric field null(s) in the substrate, where transverse magnetic (TM) modes switching between TM11 and TM02 can be accordingly realized corresponding to boresight and conical patterns. The antenna is analyzed in a cavity model, which, in terms of electric field, theoretically explains the generation of TM11 and TM02 resonant modes, and provides the audience with an innovative method of designing pattern reconfigurable antennas for the applications such as multiple-input and multiple-output (MIMO), wireless body sensor network (WBSN), Wi-Fi and WiMAX. The proposed antenna is with a competitive radius of 0.32 λg. The antenna structure is very easy to be fabricated. The measurement shows that the antenna can realize a boresight and conical pattern reconfiguration at 2.4 GHz with a gain of 6 dBi and efficiency of 86.7% (boresight mode), and 4.39 dBi and efficiency of 82.4% (conical mode).

Simorangkir, RBVB, Yang, Y & Esselle, KP 2018, 'Robust implementation of flexible wearable antennas with PDMS-embedded conductive fabric', IET Conference Publications, London, UK.
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© Institution of Engineering and Technology.All Rights Reserved. In this paper, a new approach to fabricate a robust flexible body-worn antenna is introduced. It combines conductive fabric, used as the radiator, with polydimethylsiloxane (PDMS) utilized as the substrate as well as the encapsulation of the antenna. The mechanical and electrical characteristics of PDMS-embedded conductive fabric structures are firstly investigated, followed by the general steps of the antenna fabrication process. As concept demonstrations, two designs, dual-band dual-mode and frequency-reconfigurable patch antennas, have been fabricated. Experimental investigations on the antennas' RF performance (both in free space and on a muscle phantom) and mechanical stability are also demonstrated. The latter includes bending on human's arm-shaped phantom and machine-washing tests. The results demonstrated that the proposed method is applicable for realization of robust, flexible, not only passive but also active, wearable antennas.

Suarez-Rodriguez, C, Jayawickrama, BA, Bader, F, Dutkiewicz, E & Heimlich, M 2018, 'REM-based handover algorithm for next-generation multi-tier cellular networks', IEEE Wireless Communications and Networking Conference, WCNC, IEEE Wireless Communications and Networking Conference, IEEE, Barcelona, Spain, pp. 1-6.
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© 2018 IEEE. The strongest-cell criterion has been extensively used for handover algorithms during the last cellular-network generations. When network topologies become multi-layered, it results in abrupt behaviors such as the ping-pong effect as a consequence of the power gap between tiers and their irregular deployment. This effect not only affects users' quality of experience but also introduces a significant network overhead. Therefore, we propose an original handover algorithm based on predicted incomplete channel states from a Radio Environment Map to reduce this effect. The proposed algorithm is user triggered, network assisted, and fully backward compatible with LTE-A. Moreover, we evaluate the performance of our proposed algorithm against LTE-A in a two-tier cellular network for different user speeds following the guidelines outlined by the 3GPP on diverse matters (channel, mobility, wrapping, etc.). When applying realistic timing, our results reveal a highly substantial improvement in the number of ping-pong handovers regardless of the handover policy adopted in comparison to LTE-A without sacrificing users' experience; for instance, we obtain at least an order of magnitude decrease in the ping-pong rate at the expense of losing less than 9 percent in spectral efficiency.

Suarez-Rodriguez, C, Jayawickrama, BA, He, Y, Bader, F & Heimlich, M 2017, 'Performance analysis of REM-based handover algorithm for multi-tier cellular networks', IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC, Annual International Symposium on Personal, Indoor, and Mobile Radio Communications, IEEE, Montreal, QC, Canada, pp. 1-6.
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© 2017 IEEE. The advent of 5G networks, where a plethora of spectrum-sharing schemes are expected to be adopted as an answer to the ever-growing users' need for data traffic, will require addressing mobility ubiquitously. The trend initiated with the deployment of heterogeneous networks and past standards will give way to a multi-tiered network where different services will coexist, such as device-to-device, vehicle-to-vehicle or massive-machine communications. Because of the high variability in the cell sizes given the different transmit powers, the classical handover process, which relies solely on measurements, will lead to an unbearable network overhead as a consequence of the high number of handovers. The use of spatial databases, also known as radio environment maps (REM), was first introduced as a tool to detect opportunistic spectrum access opportunities in cognitive radio applications. Since then, REM usage has been widely expanded to cover deployment optimization, interference management or resource allocation to name a few. In this paper, we introduce a handover algorithm that can predict the best network connection for the current user's trajectory from a radio environment map. We consider a geometric approach to derive the handover and handover-failure regions and compare the current handover algorithm used in Long-Term Evolution with our proposed one. Results show a drastic reduction in the number of handovers while maintaining a trade-off between the ping-pong handover and the handover-failure probabilities.

Sun, H, Ding, C & Guo, YJ 2018, 'A wideband base station antenna with reduced beam squint', IET Conference Publications.
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© 2018 Institution of Engineering and Technology.All Rights Reserved. This paper presents the design procedure, theoretical analysis, and experimental results of a novel wideband dual-polarized base station antenna. The proposed antenna consists of four electric folded dipoles arranged in an octagon shape that are excited simultaneously for each polarization. It provides the ±45° slant-polarized radiation that meets all the required specifications for base station antenna elements. Experimental results show that the proposed dual-polarized antenna has a wide bandwidth of 46.4% from 1.69 GHz to 2.71 GHz with 15 dB return loss. Across this wide bandwidth, the variations of the half-power-beamwidths (HPBWs) of the two polarizations are all within 66.5° ± 5.5°, port-to-port isolation is > 30 dB, the cross-polarization discrimination (XPD) is > 20 dB and, most importantly, the beam squint is < 4° with a maximum 10° down-tilt.

Sun, H, Ding, C, Bird, TS & Guo, YJ 2018, 'A base station antenna element with simple structure but excellent performance', 2018 Australian Microwave Symposium, AMS 2018 - Conference Proceedings, Australian Microwave Symposium, IEEE, Brsibane, QLD, Australia, pp. 35-36.
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© 2018 IEEE. A ±45° dual-polarized concentrically arranged dipole antenna is proposed for base station applications. The simple, robust antenna consists of four simple dipoles arranged in a square above a flat reflector. Two specially designed feeding networks for the two polarizations are proposed to simultaneously excite the four dipoles. Without shaping the reflector, the combination of four dipoles provides a stable radiation pattern across a wide bandwidth. Measured results show that the proposed antenna has an input reflection coefficient ≤ -14 dB from 1.71 to 2.71 GHz for both polarizations. Across this wide bandwidth (45.2%), the half-power-beamwidths (HPBWs) of the two polarizations remain very stable in the range from 60.5° to 69.5°. High port-to-port isolation ≥ 30 dB and low cross-polarization level ≤ -20 dB are achieved over the entire operating band.

Sun, H, Ding, C, Yang, T, Guo, YJ & Qin, P 2018, 'A wideband base station antenna with stable radiation pattern', 2018 Australian Microwave Symposium, AMS 2018 - Conference Proceedings, Australian Microwave Symposium, Brisbane, QLD, Australia, pp. 5-6.
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© 2018 IEEE. This paper presents the configuration and experimental results of a novel wideband dual-polarized base station antenna with superior performance. The proposed antenna consists of four electric folded dipoles arranged in an octagon shape that are excited simultaneously for each polarization. Experimental results show that this element has a wide bandwidth of 46.4% from 1.69 GHz to 2.71 GHz with ≥ 15 dB return loss. Across this wide band, the variations of the half-power-beamwidths (HPBWs) of the two polarizations are all within 66.5° ± 5.5°, the port-to-port isolation is > 28 dB, and the cross-polarization discrimination (XPD) is > 25 dB.

Ta, SX, Park, I & Ziolkowski, RW 2018, 'Reconfigurable circularly polarized cross-dipole antenna with a near-field resonant parasitic element', IET Conference Publications.
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© Institution of Engineering and Technology.All Rights Reserved. This paper presents a polarization switchable circularly polarized (CP) antenna that consists of a compact single-feed crossed dipole loaded with a near-field resonant parasitic (NFRP) element. This antenna is placed above a metallic reflector to enhance its gain and broadside radiation pattern. A meander line with an arrowhead-shaped ending was applied to all arms of the crossed dipole and NFRP elements for compactness. By adjusting the end size of the NFRP element, the antenna was capable of switching its polarization from right-hand circular polarization to left-hand circular polarization and vice versa. The reconfigurability is realized by controlling the ON/OFF states of 8 PIN-diodes, which are inserted into the arrowhead endings of the NFRP element. For the RHCP mode, the antenna yields a |S11| < -10 dB bandwidth of 1.465-1.665 GHz and a 3-dB axial ratio (AR) bandwidth of 1.535-1.590 GHz. For the LHCP mode, the antenna yields a |S11| < -10 dB bandwidth of 1.50-1.69 GHz and a 3-dB AR bandwidth of 1.545-1.585 GHz. Moreover, in both modes, the antenna yields a good broadside radiation pattern with a gain of > 6.0 dBic and a radiation efficiency of > 70% across its operational bandwidth.

Tang, MC, Chen, X, Duan, Y, Shi, T, Li, M & Ziolkowski, RW 2018, 'Designs of Compact, Flexible, Directive, Near-Field Resonant Parasitic (NFRP) Antennas', Proceedings of the 2018 IEEE 7th Asia-Pacific Conference on Antennas and Propagation, APCAP 2018, pp. 25-27.
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© 2018 IEEE. The designs of compact, low-profile, planar, flexible, directive, quasi-Yagi antennas are presented. By placing near-field resonant parasitic (NFRP) elements around the basic driven dipoles, these NFRP antennas achieve compactness, high efficiency and high directivity. The NFRP elements act either as director or reflector elements, empowering the antenna with desirable quasi-Yagi performance characteristics. These NFRP antennas are fabricated using thin substrates which can be bent without enduring any structure damage. The flexibility of these antennas is investigated under two bending conditions by mounting them on different radii cylinders. These antennas can be used in many advanced applications such as intelligent transportation system (ITS) and wearable devices.

Tang, MC, Shi, T & Ziolkowski, RW 2018, 'A 28-GHz, multi-layered, circularly polarized, electrically small, Huygens source antenna', IEEE International Symposium on Electromagnetic Compatibility, pp. 1-3.
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© 2017 IEEE. A 28 GHz, multi-layered, circularly-polarized (CP), Huygens source electrically small antenna (ESA) is presented. The CP radiation is realized by integrating two orthogonal linearly polarized Huygens source EASs into one with an asymmetrical arc strip feed providing the necessary 90° phase difference. Finally, the CP Huygens source ESA exhibits the properties: ka = 0.942; 1.41% FBW-10dB with a 0.47% 3-dB axial ratio (AR) fractional bandwidth; and peak realized gain, FTBR, and radiation efficiency values are 2.03 dBi, 26.72 dB, and 73.4%, respectively. To confirm its efficacy for on-body applications, the specific absorption rate (SAR) values of the Huygens source ESA is evaluated and found to be very low.

Tang, MC, Wang, Y, Chen, Y & Ziolkowski, RW 2018, 'Designs of Compact, Planar, Wideband, Monopole Filtennas with Near-Field Resonant Parasitic Elements', 2018 IEEE International Conference on Computational Electromagnetics, ICCEM 2018.
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© 2018 IEEE. Two planar efficient wideband, electrically small monopole filtennas are presented. The first one directly evolves from a common planar capacitively loaded loop (CLL)-based filter possessing a flat realized gain response within the operational band and good band-edge selectivity. The second filtenna consists of a driven element augmented with a CLL structure and with slots etched into its ground plane. It expands the fractional impedance bandwidth of the first case from 6.28 percent up to 7.9 percent. It also has a gain response that remains flat over its operational bandwidth and even higher band-edge selectivity. Both filtennas are electrically small with ka less than 1. The experimental results, which are in good agreement with their simulated values, demonstrate that both filtennas exhibit excellent impedance matching, high radiation efficiency, flat gain response, and steep skirts at both band edges. Moreover, they produce monopole radiation patterns that are uniform and nearly omnidirectional in their H-planes.

Todd, A, Baum, TC, Nicholson, KJ, Ziolkowski, RW & Ghorbani, K 2018, 'Towards Carbon Based Artificial Impedance Surfaces for Conformal Aerospace Applications', 2018 48th European Microwave Conference, EuMC 2018, pp. 1017-1020.
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© 2018 European Microwave Association. Conformal load-bearing smart skins (CLSS) provide the unique ability to integrate complex electrical systems into aerospace composite materials. This paper provides a preliminary investigation into the patterning of Artificial Impedance Surfaces (AIS) on these materials as they are well suited to develop conformal meta-surfaces (MTS). In particular, a composite veil material has been patterned using laser ablation and has been transferred directly onto a resin pre-impregnated (pre-preg) structural glass material. The new patterning technique was found suitable for the creation of fine geometric features with a resolution of approximately mathbf{100} mumathbf{m}. The material has been characterized by a reflected magnitude and phase measurement.

Tofigh, F, Mao, G, Lipman, J & Abolhasan, M 2018, 'Crowd Density Mapping Based on Wi-Fi Measurements on Train Platforms', 2018 12TH INTERNATIONAL CONFERENCE ON SIGNAL PROCESSING AND COMMUNICATION SYSTEMS (ICSPCS), International Conference on Signal Processing and Communication Systems, IEEE, Cairns, Australia.
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Crowd distribution is a challenging issue in the management and design levels. This paper provides a passive method to derive the crowd density distribution using Wi-Fi measurements on a real scenario. Six WiFi access points (AP) are deployed in the platform 2/3 of Redfern station, Sydney to monitor the platform for a week. Based on the probability maps that are built using RSSI measurements and prior knowledge, the crowd distribution is calculated on the platform and its results are compared with distributions acquired from CCTV images. Final density heat maps are in good agreement with the acquired results from CCTV cameras.

Umair, A, Nanda, P, He, X & Choo, K-KR 2018, 'User Relationship Classification of Facebook Messenger Mobile Data using WEKA', Springer, Lecture Notes in Computer Science, 12th International Conference on Network and System Security, Hong Kong.
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Mobile devices are a wealth of information about its user and their digital and physical activities (e.g. online browsing and physical location). Therefore, in any crime investigation artifacts obtained from a mobile device can be extremely crucial. However, the variety of mobile platforms, applications (apps) and the significant size of data compound existing challenges in forensic investigations. In this paper, we explore the potential of machine learning in mobile forensics, and specifically in the context of Facebook messenger artifact acquisition and analysis. Using Quick and Choo (2017)’s Digital Forensic Intelligence Analysis Cycle (DFIAC) as the guiding framework, we demonstrate how one can acquire Facebook messenger app artifacts from an Android device and an iOS device (the latter is , using existing forensic tools. Based on the acquired evidence, we create 199 data-instances to train WEKA classifiers (i.e. ZeroR, J48 and Random tree) with the aim of classifying the device owner’s contacts and determine their mutual relationship strength.

Vold, T, Haave, H, Ranglund, OJS, Venemyr, GO, Bakken, BT, Kiønig, L & Braun, R 2018, 'Flipped Gaming-testing three simulation games', 2018 17th International Conference on Information Technology Based Higher Education and Training (ITHET), IEEE, pp. 1-6.

Vu, L, Thuy, HV, Nguyen, QU, Ngoc, TN, Nguyen, DN, Hoang, DT & Dutkiewicz, E 2018, 'Time Series Analysis for Encrypted Traffic Classification: A Deep Learning Approach', ISCIT 2018 - 18th International Symposium on Communication and Information Technology, pp. 121-126.
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© 2018 IEEE. We develop a novel time series feature extraction technique to address the encrypted traffic/application classification problem. The proposed method consists of two main steps. First, we propose a feature engineering technique to extract significant attributes of the encrypted network traffic behavior by analyzing the time series of receiving packets. In the second step, we develop a deep learning-based technique to exploit the correlation of time series data samples of the encrypted network applications. To evaluate the efficiency of the proposed solution on the encrypted traffic classification problem, we carry out intensive experiments on a raw network traffic dataset, namely VPN-nonVPN, with three conventional classifier metrics including Precision, Recall, and F1 score. The experimental results demonstrate that our proposed approach can significantly improve the performance in identifying encrypted application traffic in terms of accuracy and computation efficiency.

Vu, T, Nguyen, D & Dutkiewicz, E 2018, '2D Proactive Uplink Resource Allocation Algorithm for Event Based MTC Applications', IEEE Wireless Communications and Networking Conference (WCNC), IEEE, Barcelona, Spain.
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We propose a two dimension (2D) proactive uplink resource allocation (2D-PURA) algorithm that aims to reduce the delay/latency in event-based machine-type communications (MTC) applications. Specifically, when an event of interest occurs at a device, it tends to spread to the neighboring devices. Consequently, when a device has data to send to the base station (BS), its neighbors later are highly likely to transmit. Thus, we propose to cluster devices in the neighborhood around the event, also referred to as the disturbance region, into rings based on the distance from the original event. To reduce the uplink latency, we then proactively allocate resources for these rings. To evaluate the proposed algorithm, we analytically derive the mean uplink delay, the proportion of resource conservation due to successful allocations, and the proportion of uplink resource wastage due to unsuccessful allocations for 2D-PURA algorithm. Numerical results demonstrate that the proposed method can save over 16.5 and 27 percent of mean uplink delay, compared with the 1D algorithm and the standard method, respectively.

Wang, H, Nguyen, D, Dinh, H, Dutkiewicz, E & Cheng, Q 2018, 'Real-Time Crowdsourcing Incentive for Radio Environment Maps: A Dynamic Pricing Approach', IEEE Global Communications Conference, UAE.
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Wang, Z, Xu, M, Ning, Y, Wang, R & Huang, H 2018, 'RF-MVO: Simultaneous 3D Object Localization and Camera Trajectory Recovery Using RFID Devices and a 2D Monocular Camera', International Conference on Distributed Computing Systems, IEEE, Vienna, Austria.
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Most of the existing RFID-based localization systems cannot well locate RFID-tagged objects in a 3D space. Limited robot-based RFID solutions require reader antennas to be carried by a robot moving along an already-known trajectory at a constant speed. As the first attempt, this paper presents RFMVO, which fuses battery-free RFID and monocular visual odometry to locate stationary RFID tags in a 3D space and recover an unknown trajectory of reader antennas binding with a 2D monocular camera. The proposed hybrid system exhibits three unique features. Firstly, since the trajectory of a 2D monocular camera can only be recovered up to an unknown scale factor, RF-MVO combines the relative-scale camera trajectory with depth-enabled RF phase to estimate an absolute scale factor and spatially incident angles of an RFID tag. Secondly, we propose a joint optimization algorithm consisting of coarse-to-fine angular refinement, 3D tag localization and parameter nonlinear optimization, to improve real-time performance. Thirdly, RFMVO can determine the effect of relative tag-antenna geometry on the estimation precision, providing optimal tag positions and absolute scale factors. Our experiments show that RF-MVO can achieve 6.23cm tag localization accuracy in a 3D space and 0.0158 absolute scale factor estimation accuracy for camera trajectory recovery.

Wu, Z, Tang, M-C & Ziolkowski, RW 2018, 'Design of Dual Linearly Polarized, Electrically Small, Low-Profile, Broadside Radiating, Huygens Source Antenna', 2018 IEEE INTERNATIONAL WORKSHOP ON ANTENNA TECHNOLOGY (IWAT), IEEE International Workshop on Antenna Technology (iWAT), IEEE, Nanjing, PEOPLES R CHINA.
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Xi, Y, Zheng, J, He, X, Jia, W & Li, H 2018, 'Beyond Context: Exploring Semantic Similarity for Tiny Face Detection', 2018 25th IEEE International Conference on Image Processing (ICIP), Athens, Greece, pp. 1907-1911.
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Xu, KD, Li, W & Liu, Y 2018, 'Dual-Frequency SIW cavity-backed slot antenna using two high-order modes', 2017 IEEE 6th Asia-Pacific Conference on Antennas and Propagation, APCAP 2017 - Proceeding, pp. 1-3.
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© 2017 IEEE. In this paper, a novel dual-frequency substrate integrated waveguide (SIW) cavity-backed slot antenna using two high-order modes is presented. Determined by the locations and types of the feeding and radiator, the high-order hybrid mode (superposition of TM310 and TM130) and another higher-order mode TM320 in SIW cavity are excited by an inductive window for dual-band application in K-band. The simulated results of the proposed antenna show that the 10-dB impedance bandwidths at resonant frequencies of 21.2 and 26.1 GHz are 400 MHz and 800 MHz, and the realized gains at boresight direction are around 10.7 and 11.9 dBi, respectively. Including its high gain, the designed dual-frequency antenna has the advantages of high front-to-back ratio and low cross polarization level.

Yang, J, Lin, W & Wong, H 2018, 'Wideband CP Polarization and Pattern Reconfigurable Antennas', 2018 IEEE International Conference on Computational Electromagnetics, ICCEM 2018, International Conference on Computational Electromagnetics, IEEE, Chengdu, China.
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© 2018 IEEE. This paper gives an review of innovative wideband CP polarization and pattern reconfigurable antennas. First, two wideband CP reconfigurable antennas with the broadside radiation patterns are presented. One design was realized by four sequentially-rotated monopoles with an output reconfigurable feed network. Another design adopted L-probes fed square patch that reduced the profile to 0.1 λ0. Second, rather than producing the broadside radiation pattern, a wideband CP reconfigurable wheel-shaped antenna with the conical-beam pattern is introduced, which is intended for geostationary satellite applications. Third, in addition to the polarization reconfigurability, a wideband CP antenna with switchable broadside and conical-beam patterns is presented, which excites both TMn and TM-21 modes on an annular slotted circular patch radiator. All the above CP polarization and pattern reconfigurable antennas are attractive for the emerging wireless communication systems, especially the satellite communication systems.

Yang, T, Ding, C, Ziolkowski, RW & Guo, YJ 2018, 'High birefringent ENZ photonic crystal fibers', Proceedings of the International Conference on Numerical Simulation of Optoelectronic Devices, NUSOD, International Conference on Numerical Simulation of Optoelectronic Devices, Hong Kong, China, pp. 85-86.
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© 2018 IEEE. A novel photonic crystal fiber (PCF) design that has a simple circular air hole configuration is reported that yields a very high birefringence. The enhanced birefringence is achieved by filling a select number of the air holes in its cladding with an epsilon-near-zero (ENZ) material to break the index symmetry of its X- A nd Y-polarization states. Comparisons of initial numerical simulations based on ideal ENZ materials and then those based on realistic ones demonstrate that the high birefringence property is still maintainable with currently available ENZ materials.

Yang, Y, Xu, M, Wu, W, Zhang, R & Peng, Y 2018, '3D Multiview Basketball Players Detection and Localization Based on Probabilistic Occupancy', 2018 INTERNATIONAL CONFERENCE ON DIGITAL IMAGE COMPUTING: TECHNIQUES AND APPLICATIONS (DICTA), International Conference on Digital Image Computing - Techniques and Applications (DICTA), IEEE, Canberra, AUSTRALIA, pp. 267-274.

Yang, Y, Zhu, H, Zhu, X & Xue, Q 2018, 'Integrated Third-Order Millimeter-Wave On-Chip Bandpass Filter using 0.13-μm SiGe Bi-CMOS Technology', IEEE MTT-S International Microwave Symposium Digest, pp. 1095-1098.
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© 2018 IEEE. This paper introduces an on-chip third-order bandpass filter (BPF) for millimeter-wave (mm-wave) applications. The proposed BPF is composed of three identical broadside-coupled meander-line resonators (BCMLR) which are jointly connected by three MIM capacitors through aT-shape network. The MIM capacitors are used as J-inverters for the implementation of the third-order BPF in order to achieve the desired multiple transmission poles and zeros across the passband and stopband, correspondingly. To fully understand the operational mechanism of the proposed high-order structure, the resonator and the proposed BPF are analyzed using an LC- equivalent circuit model for further investigation of the distribution of the transmission poles and zeros in terms of the metal inductance and MIM capacitance. To prove the concept, the proposed BPF prototype is implemented in a commercial 0.13-l.lm SiGe (Bi)-CMOS process. According to the results obtained from on-wafer measurement, three transmission poles and three transmission zeros are clearly observed. Noticeably, the proposed BPF exhibits excellent performances including a flat in-band response (less than 1 dB attenuation) from 26.7 GHz to 44.3 GHz with a measured insertion loss of 3.1 dB at the center frequency of 35.5 GHz and stopband attenuation up to 35 dB at 59 GHz. The chip size is 0.016 mm2(0.066 × 0.236 mm-), excluding the GSG pads.

Yao, L, Kusakunniran, W, Wu, Q, Zhang, J & Tang, Z 2018, 'Robust CNN-based Gait Verification and Identification using Skeleton Gait Energy Image', 2018 Digital Image Computing: Techniques and Applications (DICTA), Digital Image Computing: Techniques and Applications, IEEE, Canberra, Australia.
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Yao, Y, Zhang, J, Shen, F, Yang, W, Hua, XS & Tang, Z 2018, 'Extracting privileged information from untagged corpora for classifier learning', IJCAI International Joint Conference on Artificial Intelligence, pp. 1085-1091.
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© 2018 International Joint Conferences on Artificial Intelligence. All right reserved. The performance of data-driven learning approaches is often unsatisfactory when the training data is inadequate either in quantity or quality. Manually labeled privileged information (PI), e.g., attributes, tags or properties, is usually incorporated to improve classifier learning. However, the process of manually labeling is time-consuming and labor-intensive. To address this issue, we propose to enhance classifier learning by extracting PI from untagged corpora, which can effectively eliminate the dependency on manually labeled data. In detail, we treat each selected PI as a subcategory and learn one classifier for per subcategory independently. The classifiers for all subcategories are then integrated together to form a more powerful category classifier. Particularly, we propose a new instance-level multi-instance learning (MIL) model to simultaneously select a subset of training images from each subcategory and learn the optimal classifiers based on the selected images. Extensive experiments demonstrate the superiority of our approach.

Yu, G, Wang, X, Zha, X, Zhang, JA & Liu, R 2018, 'An Optimized Round-Robin Scheduling of Speakers for Peers-to-Peers-based Byzantine Faulty Tolerance', GlobeCom 2018, Abu Dhabi.
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Yu, Z & Chaczko, Z 2018, 'Optimization of IMU Indoor Localization with Wireless Sensors', International Conference on Computer and Communications, China, Chengdu.

Yuan, W, Shi, Q, Wu, N, Guo, Q & Huang, X 2018, 'Gaussian message passing based passive localization in the presence of receiver detection failures', IEEE Vehicular Technology Conference, pp. 1-5.
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© 2018 IEEE. This paper considers the issue of passive localization based on time of arrival (TOA) measurement in the presence of receiver detection failures. In passive localization, the signal sent from the transmitter is reflected or relayed by «passive» target and then received at several distributed receivers. The target's position can be determined by collecting range mea- surements from all receivers. With a linearized model for range measurements, we build a factor graph model and implement Gaussian message passing algorithm to obtain target location and detect link failures. The Cramer-rao bound (CRB) is also derived to evaluate the performance of proposed algorithm. Simulation results verify the effectiveness of proposed factor graph approach.

Zhang, F, Xu, KD & Liu, Y 2018, 'Compact Bandpass Filter Using Two Ring Resonators and Two Open Stubs', 2018 Cross Strait Quad-Regional Radio Science and Wireless Technology Conference, CSQRWC 2018.
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© 2018 IEEE. A compact bandpass filter (BPF) using two ring resonators and two open stubs is proposed, where fifth-order passband with twelve transmission zeros at the stopband is realized. For demonstration, a filter example with center frequency of 2.04 GHz and 3 dB fractional bandwidth of 18.6% is designed. Good performance including high selectivity in the passband and sharp stopband rejection for the filter has been realized.

Zhang, F, Xu, KD, Cai, Y, Li, M & Liu, Y 2018, 'Bandpass Filter Using Dual Series-Cascaded Ring Resonators with Multiple Transmission Zeros', 2018 IEEE International Conference on Computational Electromagnetics, ICCEM 2018.
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© 2018 IEEE. Compact dual series-cascaded ring resonators comprised of three parallel-coupled lines are proposed for design of fifth-order bandpass filter (BPF) with multiple transmission zeros. Two pairs of ±b3λg/4 parallel-coupled lines are cascaded to a pair of ±bλg/4 parallel-coupled lines to construct dual ring resonators, which can achieve a high-performance BPF with five transmission poles and eight transmission zeros. For further demonstration, a filter example centered at 2.08 GHz is designed with source-load cross coupling to obtain nine transmission zeros.

Zhang, H, Huang, X & Guo, YJ 2018, 'Low-Complexity Digital Modem Implementation for High-Speed Point-To-Point Wireless Communications', ISCIT 2018 - 18th International Symposium on Communication and Information Technology, pp. 171-175.
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© 2018 IEEE. A low-complexity digital modem is presented in this paper for achieving high-speed and wideband point-To-point (P2P) wireless communications. By combining multiple functionalities into the transmitter and receiver filters, the signal processing complexity in the digital baseband can be significantly reduced. The structures and the implementation using field programmable gate array (FPGA) for the transmitter and receiver filters are described in details. Pre-equalization for reducing the impact of practical channel frequency response can be easily incorporated into the transmitter filter structure. The experimental test results using a 20 Gigabits per second (Gbps) digital modem prototype demonstrate the satisfactory performance with low FPGA resource usage.

Zhang, J, Wu, Q, Shen, C, Zhang, J, Lu, J & van den Hengel, A 2018, 'Goal-Oriented Visual Question Generation via Intermediate Rewards', Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics), pp. 189-204.
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© 2018, Springer Nature Switzerland AG. Despite significant progress in a variety of vision-and-language problems, developing a method capable of asking intelligent, goal-oriented questions about images is proven to be an inscrutable challenge. Towards this end, we propose a Deep Reinforcement Learning framework based on three new intermediate rewards, namely goal-achieved, progressive and informativeness that encourage the generation of succinct questions, which in turn uncover valuable information towards the overall goal. By directly optimizing for questions that work quickly towards fulfilling the overall goal, we avoid the tendency of existing methods to generate long series of inane queries that add little value. We evaluate our model on the GuessWhat?! dataset and show that the resulting questions can help a standard ‘Guesser’ identify a specific object in an image at a much higher success rate.

Zhang, J, Yao, Y, Fumin, S, Wankou, Y, Pu, H & Zhenmin, T 2018, 'Discovering and Distinguishing Multiple Visual Senses for Polysemous Words', https://aaai.org/Library/AAAI/aaai18contents.php, The Thirty-Second AAAI Conference on Artificial Intelligence, The AAAI Press, New Orleans, pp. 523-530.
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To reduce the dependence on labeled data, there have been increasing research efforts on learning visual classifiers by exploiting web images. One issue that limits their performance is the problem of polysemy. To solve this problem, in this work, we present a novel framework that solves the problem of polysemy by allowing sense-specific diversity in search results. Specifically, we first discover a list of possible semantic senses to retrieve sense-specific images. Then we merge visual similar semantic senses and prune noises by using the retrieved images. Finally, we train a visual classifier for each selected semantic sense and use the learned sense-specific classifiers to distinguish multiple visual senses. Extensive experiments on classifying images into sense-specific categories and re-ranking search results demonstrate the superiority of our proposed approach.

Zhang, J, Zhang, J, Wu, Q, Wu, Q, Xu, J, Lu, J, Phua, R, Curr, K & Tang, Z 2018, 'Historical image annotation by exploring the tag relevance', Proceedings - 4th Asian Conference on Pattern Recognition, ACPR 2017, pp. 646-651.
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© 2017 IEEE. Historical images usually contain enormous historical research value and are highly related to the history objects, events and background stories etc. Therefore, annotating these images always requires selecting tags within a large set. In this paper, we propose to annotate historical images by exploring the tag relevance. We measure the tag relevance from three different perspectives, including its visual relevance, its dependencies with other tags and its relationship with location based meta-data. By using tag relevance as guidance, we generate three tag sub-sets and use them to fulfill the annotation. Experimental results on the benchmark dataset indicate the significance of exploring the tag relevance by comparing with the baseline experiments.

Zhang, L, Xu, J, Zhang, J & Gong, Y 2018, 'Information Enhancement for Travelogues via a Hybrid Clustering Model'.
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Zhang, P, Wu, Q, Xu, J & Jian, Z 2018, 'Long-Term Person Re-identification Using True Motion from Videos', Winter Conference on Applications of Computer Vision, IEEE, Lake Tahoe, NV, USA, pp. 494-502.
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Zhang, T, Lin, J, Bao, J, Cai, Z & Yang, Y 2018, 'Design of voltage-controlled oscillator with compact size and wide tuning range', 2018 Australian Microwave Symposium, AMS 2018 - Conference Proceedings, Australian Microwave Symposium, Brisbane, QLD, Australia, pp. 59-60.
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© 2018 IEEE. In this paper, a novel frequency-tunable filter based low noise voltage-controlled oscillator (VCO) is proposed. The proposed tunable filter consists of a T-type resonator with four varactors and a pair of short-ended stubs connected with feedlines. High-Q can be achieved by introducing a transmission zero on the upper stopband, which can reduce the phase noise of the VCO. The whole size of the tunable filter is 0.002λ2g. The proposed VCO was fabricated and measured indicating a promising frequency-tuning range from 2.2 to 3.2 GHz with the second harmonic suppression level of better than 22 dB. The measured phase noise is -88-91.44dBc/Hz at 100KHz offset.

Zhang, T, Yang, Z, Xu, Y, Yang, B & Jia, W 2018, 'Discriminative dictionary learning with local constraints for face recognition with occlusion', Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics), pp. 733-744.
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© Springer Nature Switzerland AG 2018. Facial occlusion, such as sunglasses, mask etc., is one important factor that affects the accuracy of face recognition. Unfortunately, faces with occlusion are quite common in the real world. In recent years, sparse coding becomes a hotspot of dealing with face recognition problem under different illuminations. The basic idea of sparse representation-based classification is a general classification scheme in which the training samples of all classes were taken as the dictionary to represent the query face image, and classified it by evaluating which class leads to the minimal reconstruction error of it. However, how to balance the shared part and class-specific part in the learned dictionary is not a trivial task. In this paper we make two contributions: (i) we present a new occlusion detection method by introducing sparse representation-based classification model; (ii) we propose a new sparse model which incorporates the representation-constrained term and the coefficients incoherence term. Experiments on benchmark face databases demonstrate the effectiveness and robustness of our method, which outperforms state-of-the-art methods.

Zhang, T, Yin, J, Cai, Z, Yang, Y & Bao, J 2018, 'X-Band Low Phase Noise Oscillator Based on Hybrid SIW Cavity Resonator', 2018 IEEE International Conference on Computational Electromagnetics, ICCEM 2018, IEEE International Conference on Computational Electromagnetics, IEEE, Chengdu, China.
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© 2018 IEEE. In this paper, a compact X-band low phase noise oscillator based on a hybrid SIW cavity resonator is presented. This proposed resonator is composed of a circular waveguide cascaded by two rectangular waveguides. Two pairs of holes are embedded into the resonator to improve the Q-factor. Owing to the existence of discontinuous metal side walls, the fundamental mode TM-110 of the circular waveguide can be applied to design the oscillation frequency of the oscillator. The fabricated oscillator has been demonstrated to oscillate at 9.5 GHz. The phase noise is less than-112.84 dBc/Hz at 100 kHz offset with 1.67 dBm output power, exhibiting the figure of merit (FOM) of-202.06 dBc/Hz.

Zhang, Z, Wu, Q, Wang, Y & Chen, F 2018, 'Fine-grained and semantic-guided visual attention for image captioning', Proceedings - 2018 IEEE Winter Conference on Applications of Computer Vision, WACV 2018, pp. 1709-1717.
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© 2018 IEEE. Soft-attention is regarded as one of the representative methods for image captioning. Based on the end-to-end CNN-LSTM framework, it tries to link the relevant visual information on the image with the semantic representation in the text (i.e. captioning) for the first time. In recent years, there are several state-of-the-art methods published, which are motivated by this approach and include more elegant fine-tune operation. However, due to the constraints of CNN architecture, the given image is only segmented to fixed-resolution grid at a coarse level. The overall visual feature created for each grid cell indiscriminately fuses all inside objects and/or their portions. There is no semantic link among grid cells, although an object may be segmented into different grid cells. In addition, the large-area stuff (e.g. sky and beach) cannot be represented in the current methods. To tackle the problems above, this paper proposes a new model based on the FCN-LSTM framework which can segment the input image into a fine-grained grid. Moreover, the visual feature representing each grid cell is contributed only by the principal object or its portion in the corresponding cell. By adopting the pixel-wise labels (i.e. semantic segmentation), the visual representations of different grid cells are correlated to each other. In this way, a mechanism of fine-grained and semantic-guided visual attention is created, which can better link the relevant visual information with each semantic meaning inside the text through LSTM. Without using the elegant fine-tune, the comprehensive experiments show promising performance consistently across different evaluation metrics.

Zhang, Z, Wu, Q, Wang, Y & Chen, F 2018, 'Size-Invariant Attention Accuracy Metric for Image Captioning with High-Resolution Residual Attention', 2018 Digital Image Computing: Techniques and Applications (DICTA), Digital Image Computing: Techniques and Applications, IEEE, Canberra, Australia.
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Zhou, Y, Ni, W, Zheng, K, Liu, RP & Yang, Y 2018, 'Node-centric route mutation for large-scale SDN based on 3D earth mover's distance model', 2017 17th International Symposium on Communications and Information Technologies, ISCIT 2017, pp. 1-6.
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© 2017 IEEE. Exploiting software-defined networking techniques, randomly and instantly mutating routes can disguise strategically important infrastructure, and protect the integrity of data networks. Route mutation has been to date formulated as NP-complete constraint satisfaction problems where feasible sets of routes need to be generated with exponential computational complexities, limiting algorithmic scalability to large-scale networks. In this paper, we propose a novel node-centric route mutation method which interprets route mutation as a signature matching problem. We formulate the route mutation problem as a three-dimensional earth mover's distance (EMD) model and solve it by using a binary branch and bound method. Considering the scalability, we further propose a heuristic method yields significantly lower computational complexities with marginal loss of robustness against eavesdropping. Simulation results show that our proposed methods can effectively disguise key infrastructure by reducing the difference of historically accumulative traffic among different switches. With significantly reduced complexities, our algorithms are of particular interest to safeguard large-scale networks.

Zhu, H & Abbosh, AM 2018, 'Wideband tunable reflection-type phase shifter using high-directivity directional coupler', 2018 Australian Microwave Symposium, AMS 2018 - Conference Proceedings, Australian Microwave Symposium (AMS), IEEE, Brisbane, QLD, Australia, pp. 49-50.
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© 2018 IEEE. A wideband tunable phase shifter that uses the concept of reflection-type phase shifter is proposed. The device is based on a tunable high-directivity directional coupler. The coupler uses two pairs of interconnected coupled-lines with suitable coplanar-waveguide transmission lines embedded within the ground plane. The tuning is realized by using two varactors and two inductors connected to two terminals of the coupler. Full-wave simulation is performed using co-simulation within ADS momentum using accurate SPICE model of the tuning elements. Moreover, a prototype is fabricated and tested. The tested results reveal that the proposed design can achieve wide operating bandwidth (105% fractional bandwidth) with 40° tuning phase.

Zhu, J, Chu, CH, Deng, L, Zhang, C, Yang, Y & Li, S 2018, 'Mm-wave high gain cavity-backed aperture-coupled patch antenna array', IEEE Access, pp. 44050-44058.
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© 2013 IEEE. A wideband and high gain cavity-backed 4 × 4 patch antenna array is proposed in this paper. Each patch antenna element of the array is enclosed by a rectangular cavity and differentially-fed by the slot underneath. By optimizing the geometry of the radiating patch and the cavity, a very uniform E-field distribution at the antenna aperture is achieved, leading to the high array aperture efficiency and thus the gain. Taking advantages of the higher-order substrate integrated cavity excitation, the elements of the array are efficiently fed with the same amplitude and phase in a simplified feeding mechanism instead of the conventional bulky and lossy power-splitter-based feeding network. Measured results show the antenna bandwidth is from 56 to 63.1-GHz (16.1%) with the peak gain reaching 21.4 dBi. The radiation patterns of the array are very stable over the entire frequency band and the cross-polarizations are as low as -30 dB. These good characteristics demonstrate that the proposed array can be a good candidate for the future 60-GHz communication system applications.

Ziolkowski, RW 2018, 'Metamaterial-inspired Compact Directive Antenna Systems', 2018 12th International Congress on Artificial Materials for Novel Wave Phenomena, METAMATERIALS 2018, pp. 468-470.
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© 2018 IEEE. Huygens dipole and multipole antennas are briefly reviewed. These electrically small systems provide enhanced directivity, a feature highly desired for current and future wireless platforms. The design, simulation, fabrication, and measurement results for the Huygens dipole antennas are discussed. The Huygens multipole antenna concepts are described. These brief examinations will be greatly expanded upon during my presentation.

Ziolkowski, RW 2018, 'Metamaterial-inspired Electrically Small Platforms: Enhanced Directivity Properties', 2018 IEEE ANTENNAS AND PROPAGATION SOCIETY INTERNATIONAL SYMPOSIUM ON ANTENNAS AND PROPAGATION & USNC/URSI NATIONAL RADIO SCIENCE MEETING, IEEE-Antennas-and-Propagation-Society International Symposium on Antennas and Propagation / USNC/URSI National Radio Science Meeting, IEEE, Boston, MA, pp. 873-874.
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Kaine, S, Rawling, MJ, Josserand, E, Boersma, M, Johns, K & Ryan, R Commonwealth Senate Education and Employment Committee 2018, 'Submission to Inquiry into the Exploitation of General and Specialist Cleaners Working in Retail chains for contracting or subcontracting cleaning companies' Centre for Business and Social Innovation UTS, pp. 1-8, Canberra.

Gill, AQ 2018, 'SECURE INFORMATION ARCHITECTURE: SECURITY BY DESIGN'.
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ACS & DAMA Joint Professional Development event 2018