Al-soeidat, M, Lu, DDC & Zhu, J 2019, 'An Analog BJT-Tuned Maximum Power Point Tracking Technique for PV Systems', IEEE Transactions on Circuits and Systems II: Express Briefs.
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IEEE In this paper, an analog, BJT-tuned voltage reference maximum power point tracking (MPPT) method for photovoltaic (PV) modules is proposed. Conventional fixed voltage reference method is the simplest method for tracking, but it does not obtain good MPPT efficiency because the maximum power point (MPP) voltage changes at different insolation levels. In reality, an approximately linear slope is formed when connecting the MPPs measured from the highest insolation level to the lowest. Utilizing this characteristic, a bipolar junction transistor (BJT), which has a similar electrical property, is used to implement a variable voltage reference that improves the accuracy of the MPP voltage when the insolation changes. The proposed circuit is simple, easy to implement and it can track the maximum power point very quickly without the need for a digital controller or PID controller. Hence, the circuit’s cost and complexity are reduced. Experimental results are given to verify the feasibility of the proposed MPPT method.
Angeloski, A, Cortie, MB, Scott, JA, Bordin, DM & McDonagh, AM 2019, 'Conversion of single crystals of a nickel(II) dithiocarbamate complex to nickel sulfide crystals', INORGANICA CHIMICA ACTA, vol. 487, pp. 228-233.
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Angeloski, A, Rawal, A, Bhadbhade, M, Hook, JM, Schurko, RW & Mcdonagh, AM 2019, 'An Unusual Mercury(II) Diisopropyldithiocarbamate Coordination Polymer', CRYSTAL GROWTH & DESIGN, vol. 19, no. 2, pp. 1125-1133.
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Bedward, TM, Xiao, L & Fu, S 2019, 'Application of Raman spectroscopy in the detection of cocaine in food matrices', Australian Journal of Forensic Sciences, vol. 51, no. 2, pp. 209-219.
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© 2017 Australian Academy of Forensic Sciences While modern methodologies for the smuggling of illicit substances often tend towards more elaborate inventions, the simple practice of concealing cocaine hydrochloride within food matrices is becoming increasingly popular. This study was conducted to develop and optimize a Raman spectroscopic method capable of identifying and quantifying cocaine hydrochloride concealed within food matrices. Samples of cocaine hydrochloride were concealed within baking powder, cake mix and white rum, with identification of the drug achieved through a combination of manual and automated detection methods and comparison with a digital spectral library. Principal component analysis (PCA) and partial least squares regression (PLSR) were employed to qualitatively and quantitatively examine the collected spectra, allowing for traces of cocaine hydrochloride found within each matrix to be identified and quantified. For each of the solid matrices, Raman spectroscopy enabled rapid, non-invasive, and unambiguous identification of the concealed drug. For the white rum samples, due to strong matrix interference, full spectrum matching was not possible, but presumptive identification of cocaine in the samples was achieved at 100%. No false positives or miss-identified samples were recorded, Results of the PLSR analysis showed potential, however difficulties in obtaining accurate concentrations served to limit the method’s use in quantitative analysis.
Cao, Y, Wang, L, Shen, C, Wang, C, Hu, X & Wang, G 2019, 'An electrochemical sensor on the hierarchically porous Cu-BTC MOF platform for glyphosate determination', SENSORS AND ACTUATORS B-CHEMICAL, vol. 283, pp. 487-494.
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Chen, Y, Zhang, W, Zhou, D, Tian, H, Su, D, Wang, C, Stockdale, D, Kang, F, Li, B & Wang, G 2019, 'Co-Fe mixed metal phosphide nanocubes with highly interconnected-pore architecture as an efficient polysulfide mediator for lithium-sulfur batteries', ACS Nano.
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Copyright © 2019 American Chemical Society. Lithium-sulfur (Li-S) batteries have been regarded as one of the most promising candidates for next-generation energy storage owing to their high energy density and low cost. However, the practical deployment of Li-S batteries has been largely impeded by the low conductivity of sulfur, the shuttle effect of polysulfides, and the low areal sulfur loading. Herein, we report the synthesis of uniform Co-Fe mixed metal phosphide (Co-Fe-P) nanocubes with highly interconnected-pore architecture to overcome the main bottlenecks of Li-S batteries. With the highly interconnected-pore architecture, inherently metallic conductivity, and polar characteristic, the Co-Fe-P nanocubes not only offer sufficient electrical contact to the insulating sulfur for high sulfur utilization and fast redox reaction kinetics but also provide abundant adsorption sites for trapping and catalyzing the conversion of lithium polysulfides to suppress the shuttle effect, which is verified by both the comprehensive experiments and density functional theory calculations. As a result, the sulfur-loaded Co-Fe-P (S@Co-Fe-P) nanocubes delivered a high discharge capacity of 1243 mAh g -1 at 0.1 C and excellent cycling stability for 500 cycles with an average capacity decay rate of only 0.043% per cycle at 1 C. Furthermore, the S@Co-Fe-P electrode showed a high areal capacity of 4.6 mAh cm -2 with superior stability when the sulfur loading was increased to 5.5 mg cm -2 . More impressively, the prototype soft-package Li-S batteries based on S@Co-Fe-P cathodes also exhibited superior cycling stability with great flexibility, demonstrating their great potential for practical applications.
Choi, S, Seo, DH, Kaiser, MR, Zhang, C, van der Laan, T, Han, ZJ, Bendavid, A, Guo, X, Yick, S, Murdock, AT, Su, D, Lee, BR, Du, A, Dou, SX & Wang, G 2019, 'WO3 nanolayer coated 3D-graphene/sulfur composites for high performance lithium/sulfur batteries', JOURNAL OF MATERIALS CHEMISTRY A, vol. 7, no. 9, pp. 4596-4603.
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Deng, J, Yu, X, Qin, X, Zhou, D, Zhang, L, Duan, H, Kang, F, Li, B & Wang, G 2019, 'Co–B Nanoflakes as Multifunctional Bridges in ZnCo 2 O 4 Micro-/Nanospheres for Superior Lithium Storage with Boosted Kinetics and Stability', Advanced Energy Materials, vol. 9, no. 14.
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© 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Transition metal oxides hold great promise as high-energy anodes in next-generation lithium-ion batteries. However, owing to the inherent limitations of low electronic/ionic conductivities and dramatic volume change during charge/discharge, it is still challenging to fabricate practically viable compacted and thick TMO anodes with satisfactory electrochemical performance. Herein, with mesoporous cobalt–boride nanoflakes serving as multifunctional bridges in ZnCo 2 O 4 micro-/nanospheres, a compacted ZnCo 2 O 4 /Co–B hybrid structure is constructed. Co–B nanoflakes not only bridge ZnCo 2 O 4 nanoparticles and function as anchors for ZnCo 2 O 4 micro-/nanospheres to suppress the severe volume fluctuation, they also work as effective electron conduction bridges to promote fast electron transportation. More importantly, they serve as Li + transfer bridges to provide significantly boosted Li + diffusivity, evidenced from both experimental kinetics analysis and density functional theory calculations. The mesopores within Co–B nanoflakes help overcome the large Li + diffusion barriers across 2D interfaces. As a result, the ZnCo 2 O 4 /Co–B electrode delivers high gravimetric/volumetric/areal capacities of 995 mAh g −1 /1450 mAh cm −3 /5.10 mAh cm −2 , respectively, with robust rate capability and long-term cyclability. The distinct interfacial design strategy provides a new direction for designing compacted conversion-type anodes with superior lithium storage kinetics and stability for practical applications.
Gao, X, Feng, J, Su, D, Ma, Y, Wang, G, Ma, H & Zhang, J 2019, 'In-situ exfoliation of porous carbon nitride nanosheets for enhanced hydrogen evolution', Nano Energy, vol. 59, pp. 598-609.
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© 2019 Elsevier Ltd The development of water splitting technology is severely impeded by the limited strategies for preparing efficient photocatalyst with optimal structure. Herein, a facile structure and doping engineering strategy is proposed to obtain the atomic-thin mesoporous graphite carbon nitride (g-C 3 N 4 ) nanosheets with a large specific surface area of 212.5 m 2 g −1 , an ultra-large pore volume of 1.55 cm 3 g −1 , high C and O contents of ∼51.4 and 4.8% via an acid-assisted exfoliation route without any hard templates. The theoretical calculation reveals that the introduction of additional C/O atoms into g-C 3 N 4 matrix would boost the charge transfer rate and charge separation efficiency due to the enhanced electronic polarization effect (Bader Charge) and shortened bond lengths. Additionally, the electronic conductivity is demonstrated to be enhanced due to the formation of delocalized π-bonding both experimentally and theoretically. The synergic contribution of textural and electronic features renders an excellent photoelectrochemical (PEC) performance with 50–60 times larger photocurrent in comparison with the pristine g-C 3 N 4 and high hydrogen evolution rates of 830.1 and 115.5 μmol g −1 h −1 under the solar- and visible-light irradiation, respectively. This in-situ exfoliation approach demonstrates a facile yet efficient method to synthesize highly porous carbon nitride materials with optimal structure and composition for efficient water splitting.
Han, C, Shi, R, Zhou, D, Li, H, Xu, L, Zhang, T, Li, J, Kang, F, Wang, G & Li, B 2019, 'High-Energy and High-Power Nonaqueous Lithium-Ion Capacitors Based on Polypyrrole/Carbon Nanotube Composites as Pseudocapacitive Cathodes', ACS Applied Materials and Interfaces.
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© 2019 American Chemical Society. The energy density of present lithium-ion capacitors (LICs) is greatly hindered by the limited specific capacities of porous carbon electrodes. Herein, we report the development of a nonaqueous LIC system by integrating two reversible electrode processes, that is, anion doping/undoping in a core-shell structured polypyrrole/carbon nanotube (Ppy@CNT) composite cathode and Li + intercalation/deintercalation in a Fe 3 O 4 @carbon (C) anode. The hybrid Ppy@CNT is utilized as a promising pseudocapacitive cathode for nonaqueous LIC applications. The Ppy provides high pseudocapacitance via the doping/undoping reaction with PF 6- anions. Meanwhile, the CNT backbone significantly enhances the electrical conductivity. The as-developed composite delivers noteworthy capacities with exceptional stability (98.7 mA h g -1 at 0.1 A g -1 and retains 89.7% after cycling at 3 A g -1 for 1000 times in Li-half cell), which outperforms state-of-art porous carbon cathodes in present LICs. Furthermore, when paired with Fe 3 O 4 @C anodes, the as-developed LICs demonstrate a superior energy density of 101.0 W h kg -1 at 2709 W kg -1 and still maintain 70 W h kg -1 at an increased power density of 17 186 W kg -1 . The findings of this work provides new knowledge on the cathode materials for LICs.
He, T, Zhu, J, Lu, DDC & Zheng, L 2019, 'Modified Model Predictive Control for Bidirectional Four-Quadrant EV Chargers with Extended Set of Voltage Vectors', IEEE Journal of Emerging and Selected Topics in Power Electronics, vol. 7, no. 1, pp. 274-281.
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© 2013 IEEE. This paper presents a modified model predictive control (MMPC) for bidirectional power flow control between the electric vehicle (EV) chargers and the main grid. In contrast to the conventional finite control set MPC which selects an optimal switching state from eight possible voltage vectors, the proposed MMPC is based on the application of an optimal voltage vector chosen from an extended set of 20 modulated voltage vectors with a fixed duty ratio. To reduce the computational burden introduced by the increased number of voltage sets, a preselection algorithm is developed for the MMPC method. Six voltage vectors are preselected from the 20 sectors. Due to the increased number of the voltage space vectors, the grid currents and active and reactive power performance can be improved by using the proposed MMPC scheme. Both the conventional and proposed methods are compared through experimental test results of a two-level three-phase off-board EV charger.
Jafari, M, Malekjamshidi, Z & Zhu, J 2019, 'A magnetically coupled multi-port, multi-operation-mode micro-grid with a predictive dynamic programming-based energy management for residential applications', International Journal of Electrical Power & Energy Systems, vol. 104, no. January 2019, pp. 784-796.
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This paper presents the development of a residential micro-grid topology based on a combination of common magnetic and electrical buses. The magnetic bus interfaces two low voltage dc buses linking a PV and a fuel cell to a high voltage dc bus connected to a grid-tied single-phase bidirectional inverter. A battery is used to store the surplus energy of the system and stabilise the dc voltage of the fuel cell bus. A synchronised bus voltage balance (SBVB) technique is used to reduce the conduction losses and increase the soft switching operation range of the converters. To improve the maximum power point tracking (MPPT) performance and system efficiency, appropriate control techniques and compensation blocks are designed. The proposed micro-grid is able to operate in multiple grid-connected and off-grid operation modes according to a predictive 2D dynamic programming-based energy management. A mode selection and transition strategy is developed to select the appropriate operation mode and smooth the mode transition. A detailed study of the micro-grid including steady-state operation, small signal modelling, controller design, and energy management is presented. A prototype of the system is developed, and experimental tests are conducted for an energy management scenario.
Jafari, M, Malekjamshidi, Z & Zhu, J 2019, 'Copper Loss Analysis of a Multi-winding High-frequency Transformer for a Magnetically-coupled Residential Micro-grid', IEEE Transactions on Industry Applications, vol. 55, no. 1, pp. 283-297.
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Improvements in characteristics of magnetic materials and switching devices have provided the feasibility of replacing the electrical buses with high-frequency magnetic links in small-scale micro-grids. This can effectively reduce the number of voltage conversion stages, size and cost of the micro-grid, and isolate the sources and loads. To optimally design the magnetic link, an accurate evaluation of copper loss of the windings considering both the current waveforms and parasitic effects are required. This paper studies the copper loss analysis of a three-winding high-frequency magnetic link for residential micro-grid applications. Due to the non-sinusoidal nature of the voltages and currents, the loss analysis is carried out on a harmonic basis taking into account the variations of phase shift, duty ratio and amplitude of the waveforms. The high-frequency parasitic phenomena including the skin and proximity effects are taken into account. The maximum and minimum copper loss operating conditions of the magnetic link and their dependency on the phase shift angle and the duty ratio of the connected waveforms are studied. A prototype of the micro-grid including the magnetic link is developed to validate the theoretical analysis, evaluate the micro-grid efficiency and perform the loss breakdown.
Jafari, M, Malekjamshidi, Z & Zhu, J 2019, 'Design and development of a multi-winding high-frequency magnetic link for grid integration of residential renewable energy systems', Applied Energy, vol. 242, pp. 1209-1225.
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© 2019 Elsevier Ltd Recent advances in magnetic material characteristics and solid-state semiconductors have provided the feasibility of replacing the electrical buses with the high-frequency multi-winding magnetic links in small-scale renewable energy systems. This effectively reduces the number of conversion stages and improves the system's efficiency, cost, and size. Other advantages are galvanic isolation between the ports, bidirectional power flow capability and flexibility in energy management and control. Despite the advantages, design and development of the multi-winding magnetic links is relatively complex and based on computationally expensive numerical methods. Furthermore, the non-sinusoidal nature of voltage and currents, high-frequency parasitic effects and nonlinearity of magnetic material characteristics increase the design complexity. In this paper, the reluctance network modeling as a fast analytical method is used to design a three winding magnetic link. The core and copper losses of the designed component are evaluated taking into account duty ratio, amplitude and phase shift of the non-sinusoidal excitation voltage and currents. The thermal analysis is carried out using an accurate thermal-electric model. A prototype of the magnetic link was developed for application in a residential renewable energy system using amorphous magnetic materials. A set of experimental tests are conducted to measure the electrical parameters, magnetic characteristics, core loss, copper loss and temperature rise of the designed component and the results are compared to the specifications to validate the design procedure.
Jafari, M, Malekjamshidi, Z, Lu, DDC & Zhu, J 2019, 'Development of a Fuzzy-Logic-Based Energy Management System for a Multi-Port Multi-Operation Mode Residential Smart Micro-grid', IEEE Transactions on Power Electronics.
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IEEE In this paper a grid-tied residential smart micro-grid topology is proposed which integrates energies of a PV, a fuel cell and a battery bank to supply the local loads through a combination of electric and magnetic buses. In contrast to multiple-converter based micro-grids with a common electric bus, using a multi-port converter with a common magnetic bus can effectively reduce the number of voltage conversion stages, size and cost of the micro-grid and isolates the conversion ports. The resultant topology utilizes a centralized system level control which leads to the faster and more flexible energy management. The proposed micro-grid is able to operate in multiple grid-connected and off-grid operation modes. A fuzzy controlled energy management unit is designed to select the appropriate operation mode considering both real-time and long-term-predicted data of the system. A mode transition process is designed to smooth the mode variation by using a state transition diagram and bridging modes. To improve the micro-grid operation performance, appropriate control techniques such as synchronized bus-voltage balance are used. A prototype of the proposed micro-grid is developed and experimentally tested for three different energy management scenarios. Energy distribution and energy cost analysis are performed to validate the proposed control method.
Jafari, M, Malekjamshidi, Z, Zhu, J & Khooban, MH 2019, 'Novel Predictive Fuzzy Logic-Based Energy Management System for Grid-connected and Off-grid Operation of Residential Smart Micro-grids', IEEE Journal of Emerging and Selected Topics in Power Electronics.
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IEEE In this paper, a novel energy management system with two operating horizons is proposed for a residential micro-grid application. The micro-grid utilises the energies of a photovoltaic (PV), a fuel cell and a battery bank to supply the local loads through a combination of electric and magnetic buses. The proposed micro-grid operates in a large number of grid-connected and off-grid operation modes. The energy management system includes a long-term data prediction unit based on a 2D dynamic programming and a short-term fuzzy controller. The long-term prediction unit is designed to determine the appropriate variation range of the battery state of charge and fuel cell state of hydrogen. The efficiency performance of the micro-grid components, predicted energy generation and demand, energy cost and the system constraints are taken into account. The resultant data then is sent to the short-term fuzzy controller which determines the operation mode of the micro-grid based on the real-time condition of the micro-grid elements. A prototype of the proposed micro-grid including the energy management system is developed, and experimental tests are conducted for three different energy management scenarios. The proposed management technique is validated through energy distribution and cost analysis.
Kang, Z, Wu, C, Dong, L, Liu, W, Mou, J, Zhang, J, Chang, Z, Jiang, B, Wang, G, Kang, F & Xu, C 2019, '3D Porous Copper Skeleton Supported Zinc Anode toward High Capacity and Long Cycle Life Zinc Ion Batteries', ACS SUSTAINABLE CHEMISTRY & ENGINEERING, vol. 7, no. 3, pp. 3364-3371.
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Khan, SA, Guo, Y & Zhu, J 2019, 'Model Predictive Observer Based Control for Single-Phase Asymmetrical T-Type AC/DC Power Converter', IEEE Transactions on Industry Applications, vol. 55, no. 2, pp. 2033-2044.
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© 1972-2012 IEEE. This paper presents a robust control strategy for the control of single-phase five-level asymmetrical T-type ac/dc power converter. A cascaded control scheme consisting of a finite control set model predictive control (FCS-MPC) with an extended state observer (ESO) is proposed to govern the converter. In this scheme, a proportional integral (PI) controller combined with an ESO-based disturbance observer is employed as an external control loop. This control loop dynamically modifies the active power reference to realize the desired operating point of the system state (converter output voltage). The proposed control system presents a high degree of disturbance rejection capability and robustness against the external disturbances to the converter, whereas the conventional PI control performance suffers in the presence of these disturbances. In this paper, the inner current tracking loop is accomplished by an FCS-MPC algorithm. This algorithm is derived to force the input currents to track the reference values while realizing a user-defined reactive power and maintaining balanced voltages in the series-connected capacitors. Theoretical analysis and the design procedure of the proposed control system are presented. Finally, experimental studies are conducted to verify the effectiveness of the proposed control scheme.
Khan, SA, Islam, MR, Guo, Y & Zhu, J 2019, 'An Amorphous Alloy Magnetic-Bus-Based SiC NPC Converter with Inherent Voltage Balancing for Grid-Connected Renewable Energy Systems', IEEE Transactions on Applied Superconductivity, vol. 29, no. 2.
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© 2002-2011 IEEE. This paper presents an amorphous alloy magnetic-bus-based neutral point clamped (NPC) converter for grid-connected renewable generation systems. In the proposed system, the amorphous alloy high-frequency high-power density multi-winding magnetic bus generates balanced dc supplies for the five-level (5L) NPC converter for high-quality power conversion. Compared to the traditional NPC converter topologies, the proposed magnetic-bus-based architecture does not require any control circuit for voltage balancing of the series connected capacitors. The magnetic bus inherently overcomes galvanic isolation issues and may reduce the size of the boosting inductor. In this paper, a finite control set model predictive control algorithm is derived to control the grid-connected 5L-NPC inverter for multilevel voltage synthesizing, while achieving the user-defined active and reactive power values. To verify the proposed concept, a simulation model is developed and analyzed in MATLAB/Simulink environment. To validate the technology, a scale d-down prototype test platform is developed in the laboratory with silicon carbide switching devices, which achieves high blocking voltage, low power dissipation, high switching frequency, and high-Temperature operation. Based on the simulation and the experimental results, it is expected that the proposed converter will have a great potential for widespread application in renewable generation systems including superconducting generator-based wind turbines.
Khan, SA, Islam, R, Guo, Y & Zhu, J 2019, 'A New Isolated Multi-Port Converter With Multi-Directional Power Flow Capabilities for Smart Electric Vehicle Charging Stations', IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY, vol. 29, no. 2.
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Kusuma, KD, Griffith, R, Harry, EJ, Bottomley, AL & Ung, AT 2019, 'In silico Analysis of FtsZ Crystal Structures Towards a New Target for Antibiotics', Australian Journal of Chemistry.
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© 2018 CSIRO. The bacterial cell division protein FtsZ is conserved in most bacteria and essential for viability. There have been concerted efforts in developing inhibitors that target FtsZ as potential antibiotics. Key to this is an in-depth understanding of FtsZ structure at the molecular level across diverse bacterial species to ensure inhibitors have high affinity for the FtsZ target in a variety of clinically relevant pathogens. In this study, we show that FtsZ structures differ in three ways: (1) the H7 helix curvature; (2) the dimensions of the interdomain cleft; and (3) the opening/closing mechanism of the interdomain cleft, whereas no differences were observed in the dimensions of the nucleotide-binding pocket and T7 loop. Molecular dynamics simulation may suggest that there are two possible mechanisms for the process of opening and closing of the interdomain cleft on FtsZ structures. This discovery highlights significant differences between FtsZ structures at the molecular level and this knowledge is vital in assisting the design of potent FtsZ inhibitors.
Lei, G, Liu, C, Li, Y, Chen, D, Guo, Y & Zhu, J 2019, 'Robust Design Optimization of a High-Temperature Superconducting Linear Synchronous Motor Based on Taguchi Method', IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY, vol. 29, no. 2.
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Li, G, Hu, J, Li, Y & Zhu, J 2019, 'An Improved Model Predictive Direct Torque Control Strategy for Reducing Harmonic Currents and Torque Ripples of Five Phase Permanent Magnet Synchronous Motors', IEEE Transactions on Industrial Electronics.
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IEEE Five phase permanent magnet synchronous motors (PMSMs) offer merits of high fault tolerant capability and high torque per rms ampere, and thus, are suitable for applications like aerospace and electric vehicles (EVs). However, the complex machine model causes difficulties in controller design. Besides, having 32 voltage vectors with various effects on currents and torque, the selection of the optimal switching state becomes a challenge to achieve a performance trade-off. This paper proposes an improved model predictive direct torque control (MPDTC) strategy consisting of a quadratic evaluation method (QEM) and a harmonic voltage elimination method (HVEM). In QEM, the preliminary vector is firstly chosen from the vectors of the outer decagon according to a cost function for torque and flux regulation. This preliminary vector, composed of three sets of different amplitudes, is further synthesized according to the error between the actual toque/flux and the references. In this way, the optimal voltage vector can be obtained without significantly increasing the computational burden. In HVEM, by subtracting the harmonics voltage component from the vector determined previously in QEM, the final voltage vector is obtained for mitigating stator harmonic currents. The proposed control strategy is compared with the conventional MPDTC approach. The results confirm the effectiveness of the proposed methods with good steady-state performance while maintaining quick dynamic responses.
Li, N, Fu, X, Zhu, J, Lin, M, Yang, G, Kong, Y & Hao, L 2019, 'Hybrid-Excited Series Permanent Magnet Axial Field Flux Switching Memory Machine', IEEE Transactions on Applied Superconductivity, vol. 29, no. 2.
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© 2002-2011 IEEE. This paper presents a novel axial field flux switching memory (AFFSM) machine, which integrates series permanent magnet (SPM) and an additional dc field winding for improving the flux regulation capability. The configuration and the operation principle of the SPM-AFFSM machine are presented. The design considerations for the SPM and the dc field winding are discussed. The voltage regulation capability and torque-speed characteristics of the SPM-AFFSM machine are investigated by 3-D FEA. Finally, a prototype is developed for experimental verification. The measured results verify structural validity and the finite-element predictions.
Li, P, Guo, X, Wang, S, Zang, R, Li, X, Man, Z, Li, P, Liu, S, Wu, Y & Wang, G 2019, 'Two-dimensional Sb@TiO2-x nanoplates as a high-performance anode material for sodium-ion batteries', JOURNAL OF MATERIALS CHEMISTRY A, vol. 7, no. 6, pp. 2553-2559.
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Li, T, Xu, J, Wang, C, Wu, W, Su, D & Wang, G 2019, 'The latest advances in the critical factors (positive electrode, electrolytes, separators) for sodium-sulfur battery', Journal of Alloys and Compounds, vol. 792, pp. 797-817.
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© 2019 The sodium-sulfur (Na/S) batteries have caused widespread concern owing to the advantages of low cost and high energy density, these advantages make them promising in the large-scale energy storage system. But the research progress in this field is still at the beginning stage and confronts with tough challenges, for example, the low sulfur conductivity and polysulfide shuttle effect. Considering Na/S battery is a complicated system whose reaction mechanism between sulfur and sodium is different from the operating temperatures, positive electrode hosts and electrolytes, thus a comprehensive understanding about the electrochemistry of the Na/S batteries that operating in high-temperature, intermediate-temperature and room-temperature is necessary. In addition, the critical factors (positive electrodes, electrolytes, separators) associated with the development of high energy density and high performance Na/S battery, it also need to be analysed for the successful application in the near future. In this review, the working methods of high-temperature Na/S (HT-Na/S) battery, intermediate-temperature Na/S (IT-Na/S) battery and room-temperature Na/S (RT-Na/S) battery will be compared, and also focus on the latest progress of positive electrodes, electrolytes and separators in Na/S batteries. Finally, we provide an outlook on the state of the art for the production of more efficient and reliable Na/S batteries with rational technique.
Li, X, Wang, S, Tang, X, Zang, R, Li, P, Li, P, Man, Z, Li, C, Liu, S, Wu, Y & Wang, G 2019, 'Porous Na3V2(PO4)(3)/C nanoplates for high-performance sodium storage', JOURNAL OF COLLOID AND INTERFACE SCIENCE, vol. 539, pp. 168-174.
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Liu, Y, Xu, W, Zhu, J & Blaabjerg, F 2019, 'Sensorless Control of Standalone Brushless Doubly Fed Induction Generator Feeding Unbalanced Loads in a Ship Shaft Power Generation System', IEEE Transactions on Industrial Electronics, vol. 66, no. 1, pp. 739-749.
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© 1982-2012 IEEE. The standalone brushless doubly fed induction generator (BDFIG) has demonstrated excellent energy-saving performance in ship shaft power generation applications. As a standalone system, it exhibits unbalanced terminal voltages and poor performance under unbalanced loads. However, the existing control scheme of grid-connected BDFIGs cannot be directly applied to stabilize the amplitude and frequency of terminal voltage when the rotor speed and electrical load vary. This paper presents a new sensorless control scheme for the standalone BDFIG under unbalanced load conditions in the ship shaft power generation system. A second-order generalized integrator-based quadrature signal generator is introduced to realize the rotor speed observer for the standalone BDFIG feeding unbalanced loads. The compensation method of negative-sequence power winding voltage is proposed to eliminate the negative-sequence component of the unbalanced power winding voltage. Comprehensive experiments are carried out on a prototype BDFIG with and without the compensation of negative-sequence power winding voltage. The good performance of the proposed sensorless control scheme is verified by the experimental test results.
Luo, CQ, Ling, FCC, Rahman, MA, Phillips, M, Ton-That, C, Liao, C, Shih, K, Lin, J, Tam, HW, Djurišić, AB & Wang, SP 2019, 'Surface polarity control in ZnO films deposited by pulsed laser deposition', Applied Surface Science, vol. 483, pp. 1129-1135.
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© 2019 Elsevier B.V. We demonstrate a simple and inexpensive method of surface polarity control of ZnO grown by pulsed laser deposition (PLD). The polarity control is achieved in a straightforward way by changing the thickness of MgO buffer layer. The Zn- and O-polar ZnO films possess very distinct growth rate, electron concentration and mobility as well as different defect structures. These different structural and electronic properties result in significant differences in surface reactivity and device performance. For example, Pd Schottky diodes fabricated onto the O-polar ZnO film exhibit lower barrier height and ideality factor compared with the equivalent Zn-polar devices, while methylammonium lead iodide perovskite films are readily formed on O-terminated and rapidly decompose on Zn-terminated surfaces. This can be attributed to higher photocatalytic activity of Zn-terminated surface, as well as higher surface coverage of adsorbed hydroxyl groups. Consequently, our results indicate that polarity engineering to obtain favorable O-terminated surface can result in improved performance of ZnO-containing optoelectronic devices, while Zn-terminated surfaces could be of interest for photocatalytic and sensing applications.
Luo, L, Zhang, H, Song, L, Liu, L, Yi, X, Tan, M, Song, J, Wang, G & Wang, F 2019, 'Phase transition induced synthesis of one dimensional In1-xZnxOy heterogeneous nanofibers for superior lithium ion storage', APPLIED SURFACE SCIENCE, vol. 470, pp. 340-347.
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Mahamedi, B, Eskandari, M, Fletcher, JE & Zhu, J 2019, 'Sequence-Based Control Strategy with Current Limiting for the Fault Ride-Through of Inverter-Interfaced Distributed Generators', IEEE Transactions on Sustainable Energy.
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IEEE Three-phase three-leg inverters comprise the majority of inverters that are integrated into power grids. They can develop positive- and negative-sequence components under unbalanced conditions including asymmetrical faults, but not zero sequence. This indicates that a sequence-based control strategy is required for a comprehensive control of inverter currents and voltages, hence positive- and negative-sequence components must be controlled separately with their own dedicated controllers. Given this critical need, a sequence-based control technique for grid-forming and grid-feeding inverter-interfaced distributed generators (IIDG) is proposed. As a necessary part of the fault ride-through (FRT) capability of IIDGs, a current limiter is developed which can limit inverter currents at a pre-defined threshold for both balanced and unbalanced faults/voltage sags. Whilst the current regulators work in the synchronous reference frame with simple PI controllers, the limiter works in natural reference frame and thus treats each phase current separately, which results in current limiting at the threshold for all phases. The advantage of the proposed limiter is that it virtually acts instantaneously such that the inverter current can be limited from the start of the disturbance. The simulation results in MATLAB/SIMULINK reveal promising performance of the proposed control strategy with the proposed current limiting.
Malekjamshidi, Z, Jafari, M, Zhu, J & Xiao, D 2019, 'Bidirectional power flow control with stability analysis of the matrix converter for microgrid applications', International Journal of Electrical Power and Energy Systems, vol. 110, pp. 725-736.
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© 2019 Elsevier Ltd In this paper, the importance of the matrix converter stabilization in bidirectional power flow control is investigated. A stabilization technique for matrix converters based on a combination of the damping resistor and the input digital filter is proposed. The suggested technique is applied to a direct matrix converter employed as an interface between two power sources as the main grid and a microgrid to realize a stable four-quadrant power flow control process. The control method is based on the voltage oriented control strategy using anti-windup proportional-integral controllers. The stability analysis using the small-signal model of the converter is presented and simulated numerically. The proposed stabilization and bidirectional power flow control methods are validated by experimental tests on a prototype.
Man, Z, Li, P, Zhou, D, Zang, R, Wang, S, Li, P, Liu, S, Li, X, Wu, Y, Liang, X & Wang, G 2019, 'High-performance lithium-organic batteries by achieving 16 lithium storage in poly(imine-anthraquinone)', JOURNAL OF MATERIALS CHEMISTRY A, vol. 7, no. 5, pp. 2368-2375.
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Meng, L, Ren, Y, Zhou, Z, Li, C, Wang, C & Fu, S 2019, 'Monodisperse silica nanoparticle suspension for developing latent blood fingermarks', Forensic Sciences Research, pp. 1-9.
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Miao, H, Teng, Z, Wang, C, Chong, H & Wang, G 2019, 'Recent Progress in Two-Dimensional Antimicrobial Nanomaterials', CHEMISTRY-A EUROPEAN JOURNAL, vol. 25, no. 4, pp. 929-944.
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Rahman, MA, Islam, MR, Muttaqi, KM, Guo, Y, Zhu, J, Sutanto, D & Lei, G 2019, 'A Modified Carrier-Based Advanced Modulation Technique for Improved Switching Performance of Magnetic-Linked Medium-Voltage Converters', IEEE Transactions on Industry Applications, vol. 55, no. 2, pp. 2088-2098.
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© 1972-2012 IEEE. The high-frequency magnetic link is gaining popularity due to its lightweight, small volume, and inherent voltage balancing capability. Those features can simplify the utilization of a multilevel converter (MLC) for the integration of renewable energy sources to the grid with compact size and exert economic feasibility. The modulation and control of the MLC are crucial issues, especially for grid-connected applications. To support the grid, the converter may need to operate in an overmodulation (OVM) region for short periods depending upon the loading conditions. This OVM operation of the converter causes increased harmonic losses and adverse effects on the overall system efficiency. On top of that, the size and cost of filtering circuitry become critical to eliminate the unwanted harmonics. In this regard, a modified OVM scheme with phase-disposed carriers for a grid-connected high-frequency magnetic-link-based cascaded H-bridge (CHB) MLC is proposed for the suppression of harmonics and the reduction of converter loss. Furthermore, with the proposed OVM technique, the voltage gain with the modulation index can be increased up to the range which is unlikely to be achieved using the classical ones. Extensive simulations are carried out with a 2.24 MVA permanent magnet synchronous generator based wind energy conversion system, which is connected to the 11 kV ac grid through a high-frequency magnetic-link and a five-level CHB MLC. A scaled down laboratory prototype is implemented to validate the performance of the converter.
Sahu, TS, Choi, S, Jaumaux, P, Zhang, J, Wang, C, Zhou, D & Wang, G 2019, 'Squalene-derived sulfur-rich copolymer@ 3D graphene-carbon nanotube network cathode for high-performance lithium-sulfur batteries', POLYHEDRON, vol. 162, pp. 147-154.
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Sarker, PC, Islam, MR, Guo, Y, Zhu, J & Lu, HY 2019, 'State-of-The-Art Technologies for Development of High Frequency Transformers with Advanced Magnetic Materials', IEEE Transactions on Applied Superconductivity, vol. 29, no. 2.
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© 2002-2011 IEEE. With the development of advanced soft magnetic materials of high-saturation flux density and low specific core loss and semiconductor power devices, the high-frequency transformer (HFT) has received significant attention in recent years for its widespread emerging applications. The optimal design of high-power-density HFTs for high-performance energy conversion systems is, however, a multiphasic problem that needs special considerations on various aspects such as core material selection, minimization of parasitic components, and thermal management. This paper presents a comprehensive review on advancement of soft magnetic materials for high-power-density magnetic devices and advanced technologies for characterizations and optimal design of HFTs. The future research and development trends are also discussed.
Shi, X, Zhu, J, Li, L & Lu, DDC 2019, 'Model-Predictive-Based Duty Cycle Control with Simplified Calculation and Mutual Influence Elimination for AC/DC Converter', IEEE Journal of Emerging and Selected Topics in Power Electronics, vol. 7, no. 1, pp. 504-514.
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© 2013 IEEE. The single-vector-based model-predictive-based direct power control (MPDPC) is commonly used for control of three-phase full-bridge ac/dc converters, but it could only select the best switching vector to be implemented. Due to the limited number of voltage vectors in a two-level three-phase converter, the sampling frequency needs to be high to achieve an acceptable performance. Also, it bears variable switching frequency that causes spread spectrum nature of harmonics. In this paper, a three-vector-based simplified model predictive duty cycle control (SMPDCC) is proposed. The adjacent two nonzero vectors are selected by evaluating the effects of each vector pairs based on the revised cost function. The duration calculation is simplified compared with the conventional predictive duty cycle control (CPDCC) by allocating a control period in reciprocal proportion with the corresponding cost function value of the selected vectors. Besides, the negative duration issue of CPDCC could be completely avoided and the mutual influence elimination ability could be realized. A comparative study with MPDPC and CPDCC has been conducted to verify the superiority of the proposed scheme by the simulation and experimental results. It shows that the SMPDCC has the advantages of lower power ripple, fixed switching frequency, lower total harmonic distortion, and mutual influence elimination ability.
Shi, X, Zhu, J, Li, L, Lu, DDC, Zhang, J & Yang, H 2019, 'Predictive Duty Cycle Control with Reversible Vector Selection for Three-Phase AC/DC Converters', IEEE Transactions on Power Electronics.
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IEEE The conventional predictive duty cycle control (CPDCC) of three-phase full-bridge AC/DC converters selects adjacent non-zero vector pair based on the grid-voltage vector location, then the duration for each vector is calculated. Though the vector selection method is quite simple, it has a significant disadvantage that the values of calculated durations could be frequently less than zero due to non-optimal vector selection, which results in high current harmonics and power notches. It could be improved with improved predictive duty cycle control (IPDCC) by reselecting the non-zero vector pair when negative duration exists, however, the whole vector selection and calculation procedure are repeated. By theoretical verification that the power variation rates of reversible vector pair are symmetrical with respect to that of zero vector, this paper proposes the reversible predictive duty cycle control (RPDCC) simply by replacing the original vector with its opposite vector and the recalculation of vector duration is eliminated compared with IPDCC. Thus the calculation effort is almost not increased compared with CPDCC while system performance is significantly improved. The proposed control is theoretically derived and verified with the simulation and experimental results showing that RPDCC has better steady and dynamic performance than CPDCC and IPDCC methods.
Shi, Z, Sun, X, Cai, Y, Yang, Z, Lei, G, Guo, Y & Zhu, J 2019, 'Torque Analysis and Dynamic Performance Improvement of a PMSM for EVs by Skew Angle Optimization', IEEE Transactions on Applied Superconductivity, vol. 29, no. 2.
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© 2018 IEEE. In this paper, a permanent magnet synchronous machine (PMSM) for electric vehicles (EVs) is studied. Since EVs need to face some low speed road conditions, it is necessary to drive the machine to maintain a stable torque at low speed. The stator skew slot is often adopted to reduce torque ripple; however, it declines the output torque at same time. Besides, the difference between positive rotation performance and negative rotation performance, which caused by the skew slot are often ignored. Through the finite element analysis, the cogging torque and dynamic performance of the PMSM at different skew angle are studied. Moreover, the different influence of slot skew angle on positive and negative rotation performance is studied. Then, the optimum skew angle of the PMSM is studied through comprehensive consideration. Finally, the cogging torque of the prototype is verified to be less than 2 N·m through the experiment.
Song, J, Guo, X, Zhang, J, Chen, Y, Zhang, C, Luo, L, Wang, F & Wang, G 2019, 'Rational design of free-standing 3D porous MXene/rGO hybrid aerogels as polysulfide reservoirs for high-energy lithium-sulfur batteries', JOURNAL OF MATERIALS CHEMISTRY A, vol. 7, no. 11, pp. 6507-6513.
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Tang, X, Zhou, D, Li, P, Guo, X, Wang, C, Kang, F, Li, B & Wang, G 2019, 'High-Performance Quasi-Solid-State MXene-Based Li-I Batteries', ACS CENTRAL SCIENCE, vol. 5, no. 2, pp. 365-373.
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Teng, Z, Yang, N, Lv, H, Wang, S, Hu, M, Wang, C, Wang, D & Wang, G 2019, 'Edge-Functionalized g-C3N4 Nanosheets as a Highly Efficient Metal-free Photocatalyst for Safe Drinking Water', CHEM, vol. 5, no. 3, pp. 664-680.
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Tian, H, Shao, H, Chen, Y, Fang, X, Xiong, P, Sun, B, Notten, PHL & Wang, G 2019, 'Ultra-stable sodium metal-iodine batteries enabled by an in-situ solid electrolyte interphase', NANO ENERGY, vol. 57, pp. 692-702.
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Wang, S, Wang, Y, Liu, C, Lei, G, Guo, Y & Zhu, J 2019, 'Comparative Study of Linear Superconductivity Machine with Different Stator and Winding Configurations', IEEE Transactions on Applied Superconductivity, vol. 29, no. 2.
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IEEE Compared with rotary electrical machine in linear drive applications, linear machine without rotary-linear motion conversion equipment can have higher force density and efficiency. Linear superconductivity machine (LSM) consists of high performance superconducting magnet instead of permanent magnet can offer very high force density and efficiency compared with other linear machines, such as linear induction machine, linear permanent magnet machine and so on. In this paper, LSM with different stators and winding configurations are investigated, specifically LSMs with concentrated winding or distributed winding and unilateral side stator or bilateral side stator. The electromagnetic parameters and performance of these LSMs are calculated and compared by using the finite element method (FEM), then the main difference of various design methods in LSM have been concluded.
Wang, Z, Luo, C, Anwand, W, Wagner, A, Butterling, M, Rahman, MA, Phillips, MR, Ton-That, C, Younas, M, Su, S & Ling, FC-C 2019, 'Vacancy cluster in ZnO films grown by pulsed laser deposition', SCIENTIFIC REPORTS, vol. 9.
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Wei, X, Cheng, M, Zhu, J, Yang, H & Luo, R 2019, 'Finite-Set Model Predictive Power Control of Brushless Doubly Fed Twin Stator Induction Generator', IEEE Transactions on Power Electronics, vol. 34, no. 3, pp. 2300-2311.
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© 1986-2012 IEEE. This paper presents a finite-set model predictive power control (FS-MPPC) method for the brushless doubly fed twin stator induction generator (BDFTSIG) in variable speed constant frequency generation applications. The FS-MPPC controller is developed in a general reference frame from which all other reference frames can be deduced readily. The invariant feature of the predictive power model in various reference frames contributes to the reference frame-free characteristic of the developed FS-MPPC controller, enabling its application more flexible and universal. Besides, the arduous process of control winding flux estimation is avoided in the FS-MPPC controller by choosing state variables that are easy to be obtained. Moreover, the influence of rotor circuit that has long been neglected in the existing controllers for the brushless doubly fed induction machines is embedded within the predictive power model and inherently considered in the FS-MPPC controller, which contributes to accurate power control of the BDFTSIG. Furthermore, the feasibility and effectiveness of the developed FS-MPPC controller regarding different power levels and grid fault conditions are briefly discussed. Finally, numerical simulations and experimental tests are carried out, which demonstrates the effectiveness of the developed FS-MPPC controller.
Wu, T, Lu, K, Zhu, J, Lei, G, Guo, Y & Tang, S 2019, 'Calculation of Eddy Current Loss in a Tubular Oscillatory LPMSM Using Computationally Efficient FEA', IEEE Transactions on Industrial Electronics.
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IEEE In some special oscillatory applications, especially those operated at high speeds, the eddy current loss of linear permanent magnet (PM) synchronous machine (LPMSM) should be fully considered because the loss might be large and concentrated in PMs during the oscillation period. This paper presents a loss analysis method based on computationally efficient finite element analysis (CE-FEA) for a 20 Hz oscillatory tubular LPMSM. Since the mover speed varies with time, an equally-divided model in 1/4 period is introduced to calculate the average PM eddy current loss. The flux density curves in PMs are calculated at 18 intervals by the CE-FEA, through which the change rate of magnetic flux density is analyzed, considering both the entering and leaving effects and coil end effects. The calculation results show that the eddy current loss is obviously concentrated in PMs near the two ends of coils. The calculation results at a speed of 3.6 m/s obtained by the CE-FEA and 2D&3D time-stepping FEAs are compared to validate the accuracy. Finally, the proposed method is validated by the experimental test results on a prototype LPMSM.
Wu, W, Qi, W, Zhao, Y, Tang, X, Qiu, Y, Su, D, Fan, H & Wang, G 2019, 'Hollow CeO2 spheres conformally coated with graphitic carbon for highperformance supercapacitor electrodes', APPLIED SURFACE SCIENCE, vol. 463, pp. 244-252.
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Wu, W, Zhao, Y, Li, S, He, B, Liu, H, Zeng, X, Zhang, J & Wang, G 2019, 'P doped MoS 2 nanoplates embedded in nitrogen doped carbon nanofibers as an efficient catalyst for hydrogen evolution reaction', Journal of Colloid and Interface Science, vol. 547, pp. 291-298.
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© 2019 Elsevier Inc. Two-dimensional (2D) molybdenum sulfide (MoS 2 ) is considered as a promising catalyst for hydrogen evolution reaction (HER), originated from its abundant hydrogen evolution active sites. However, the HER performance of MoS 2 is currently hindered by the limited exposed density of the active sites and low conductivity. Herein, we report a facile and scalable electrospinning technique to fabricate 2D MoS 2 nanoplates doped with phosphorus within one-dimensional nitrogen doped-carbon nanofibers (NCNFs-MoS 2 |P) as a highly efficient HER catalyst. The space-confined growth with the presence of NCNFs avoided the stacking and aggregation of the MoS 2 nanoplates, resulting in more exposed edge sites. The introduction of phosphorus atoms further activated the surface of MoS 2 and enhanced the electron transfer. The overpotential of NCNFs-MoS 2 |P reached 98 mV at 10 mA cm −2 , exhibiting excellent HER catalytic activity. Besides, almost no decay was observed after the stability test (5000 cycles or 20 h). The density functional calculations (DFT) elucidated that the incorporation of phosphorus atoms significantly improved the electrical conductivity and decreased the H adsorption energy barrier on MoS 2 , leading to a high catalytic performance of NCNFs-MoS 2 |P.
Xiong, P, Ma, R, Wang, G & Sasaki, T 2019, 'Progress and perspective on two-dimensional unilamellar metal oxide nanosheets and tailored nanostructures from them for electrochemical energy storage', Energy Storage Materials.
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© 2018 Elsevier B.V. Research on molecularly thin two-dimensional (2D) nanosheets has experienced significant progress since the discovery of graphene. Due to the high tunability of the structure, composition, and functionality, a great number of recent studies have focused on 2D ultrathin metal oxides, which have shown promising perspectives in many fields, including electrochemical energy storage. In this review, we focus on recent advances in 2D genuine unilamellar metal oxide nanosheets delaminated from their layered parent precursors and overview nanostructured materials based on these nanosheets for electrochemical energy storage applications. In particular, new, molecular-scale integrated superlattice structures fabricated by facile solution-based strategies using 2D unilamellar metal oxide nanosheets as building blocks are highlighted as emerging electrode materials to provide ultimately enhanced performance. Finally, current opportunities and future challenges for research into 2D unilamellar metal oxide nanosheets are proposed and outlined.
Xu, W, Dian, R, Liu, Y, Hu, D & Zhu, J 2019, 'Robust Flux Estimation Method for Linear Induction Motors Based on Improved Extended State Observers', IEEE Transactions on Power Electronics, vol. 34, no. 5, pp. 4628-4640.
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IEEE Flux estimation is of great importance for high performance linear induction motor (LIM) drives. However, due to the end effects of LIMs, the mutual inductance and secondary resistance are seriously varied with the operation condition changing, and the flux estimation suffers from these LIM parameter variations. To alleviate the influence of these parameter variations, this paper proposes a new flux estimation algorithm based on two improved extended state observers (ESOs) with expanded bandwidth for observing disturbances. One of them is specially designed to observe the ac disturbance at certain frequency. Taking advantage of the improved ESOs, the robustness of the flux observer to parameter deviations can be significantly strengthened, and the vector control strategy based on this new flux observer can achieve better dynamic performance. Lastly, the effectiveness of the proposed method is validated by both simulation and experimental results on an LIM prototype.
Yang, J, Bao, W, Jaumaux, P, Zhang, S, Wang, C & Wang, G 2019, 'MXene-Based Composites: Synthesis and Applications in Rechargeable Batteries and Supercapacitors', Advanced Materials Interfaces, vol. 6, no. 8.
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© 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim The family of 2D transition metal carbides, nitrides, and carbonitrides (collectively called MXenes) is rapidly studied since the initial synthesis of Ti 3 C 2 T x (MXene). The surface of MXenes etched by hydrofluoric acid has hydrophilic groups (F, OH, and O), which leads the surface to be negatively charged. Consequently, the negatively charged surface can facilitate the compounding of MXenes with other positively charged materials and prevent MXenes from aggregating with some negatively charged substances, thus promoting the formation of a stable dispersion. The MXene-based composites have better electrochemical performance than both precursors due to synergistic effects. This review elaborates and discusses the development of MXene-based composites. It is aimed to summarize the various methods of fabricating MXene-based composites. The applications of MXene-based composites in batteries and supercapacitors are presented along with analysis of their excellent electrochemical performances. Finally, the authors propose the approach for further enhancing the electrochemical performances of MXene-based composite electrode materials.
Yang, T, Liu, Y, Yang, D, Deng, B, Ling, CD, Liu, H, Wang, G, Guo, Z & Zheng, R 2019, 'Bimetallic metal-organic frameworks derived Ni-Co-Se@C hierarchical bundle-like nanostructures with high-rate pseudocapacitive lithium ion storage', Energy Storage Materials, vol. 17, pp. 374-384.
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© 2018 Metal-organic frameworks and its derivates have attracted much attention for energy storage application. In this work, three-dimensional bimetallic metal-organic frameworks with novel hierarchical bundle-like micro/nanostructure were synthesized at room temperature for the first time. After initial carbonization and subsequent selenization, hierarchical porous Ni-Co-Se nanoparticles embedded in 3D carbon network with a high surface area that obviously inherited the original morphology of the bimetallic metal organic frameworks. The resulting materials demonstrated superior performance as the anode in lithium ion batteries (LIBs): they provide high reversible Li-storage capacity, excellent cyclability (2061 mA h/g after 300 cycles) and high rate performance (493 mA h/g at 8 A/g). The features of Ni-Co-Se@C electrode include the synergistic effect of two metal selenides species for Li-storage, well-designed hierarchical porous bundle-like structure, steady carbon network and as-formed size-reduced particles after initial cycle process. These features not only enhanced the electronic properties and alleviated the volume variation of metal selenides during the repeated cycles, but also produced more active sites for lithium storage and a shorter lithium diffusion pathway to expedite the fast charge transfer and preserve a stable SEI layer, resulting in outstanding lithium storage performance. In addition, the pseudocapacitive behaviour contributes much to the high energy storage of lithium ions. These results uncover a facile methodology for the design of well-organized MOFs and transition metal dichalcogenides with 3D hierarchical structures.
Yang, T, Yang, D, Mao, Q, Liu, Y, Bao, L, Chen, Y, Xiong, Q, Ji, Z, Ling, CD, Liu, H, Wang, G & Zheng, R 2019, 'In-situ synthesis of Ni-Co-S nanoparticles embedded in novel carbon bowknots and flowers with pseudocapacitance-boosted lithium ion storage', NANOTECHNOLOGY, vol. 30, no. 15.
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Ye, X, Yang, Z, Zhu, J & Guo, Y 2019, 'Modeling and Operation of a Bearingless Fixed-Pole Rotor Induction Motor', IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY, vol. 29, no. 2.
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Yu, X, Yu, ZY, Zhang, XL, Zheng, YR, Duan, Y, Gao, Q, Wu, R, Sun, B, Gao, MR, Wang, G & Yu, SH 2019, '"superaerophobic" Nickel Phosphide Nanoarray Catalyst for Efficient Hydrogen Evolution at Ultrahigh Current Densities', Journal of the American Chemical Society, vol. 141, no. 18, pp. 7537-7543.
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Copyright © 2019 American Chemical Society. The design of highly efficient non-noble-metal electrocatalysts for large-scale hydrogen production remains an ongoing challenge. We report here a Ni 2 P nanoarray catalyst grown on a commercial Ni foam substrate, which demonstrates an outstanding electrocatalytic activity and stability in basic electrolyte. The high catalytic activity can be attributed to the favorable electron transfer, superior intrinsic activity, and the intimate connection between the nanoarrays and their substrate. Moreover, the unique "superaerophobic" surface feature of the Ni 2 P nanoarrays enables a remarkable capability to withstand internal and external forces and release the in situ generated H 2 bubbles in a timely manner at large current densities (such as >1000 mA cm -2 ) where the hydrogen evolution becomes vigorous. Our results highlight that an aerophobic structure is essential to catalyze gas evolution for large-scale practical applications.
Zhang, F, Xiong, P, Guo, X, Zhang, J, Yang, W, Wu, W, Liu, H & Wang, G 2019, 'A nitrogen, sulphur dual-doped hierarchical porous carbon with interconnected conductive polyaniline coating for high-performance sodium-selenium batteries', Energy Storage Materials.
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© 2019 Elsevier B.V. Sodium-selenium (Na-Se) battery has been emerging as a new rechargeable energy storage system with high capacity, low cost and high rate capability. However, the shuttling of polyselenides from the cathode to the anode causes dramatic capacity decay, severely impeding their practical applications. Herein, we report a combinational strategy of nitrogen and sulphur dual-doped hierarchical porous carbon with interconnected conductive polyaniline (PANI) coating to incorporate Se as stable cathodes (i-PANI@NSHPC/Se) for Na-Se batteries. Ex situ characterizations and density functional theory (DFT) calculations demonstrate that the i-PANI@NSHPC/Se cathode can provide both physical diffusion barrier and strong chemical affinity for polyselenides. In addition, the interconnected conductive polyaniline network enhances the conductivity for electrons and ions. With this strategy, the i-PANI@NSHPC/Se cathode delivered a high reversible capacity of 617 mAh g −1 after 200 cycles at 0.2C with a low capacity decay rate of 0.013% per cycle and an excellent rate capability at 20 C. Importantly, stable cycling performances were achieved with high capacities at different Se areal mass loadings (1.2, 2.3, 3.5 mg cm −2 ). This work could provide an efficient approach for developing Na-Se batteries with high active material mass loading, high rate capacity and long cycle life.
Zhang, J, Sade, H, Zhao, Y, Murdock, AT, Bendavid, A, Lellouche, J-P, Wang, G & Han, Z 2019, 'Conformal carbon coating on WS2 nanotubes for excellent electrochemical performance of lithium-ion batteries.', Nanotechnology, vol. 30, no. 3, pp. 035401-035401.
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WS2 nanotubes with carbon coatings in a core-shell structure (i.e. WS2@C) are synthesized through a facile method based on the Lewis acid-activated thioglycosylation chemistry. The obtained WS2@C shows a conformal coverage of conductive amorphous carbon on the surface of WS2 after thermal treatment, with the thickness of carbon layer being controlled by adjusting the molar ratios of saccharide to nanotube during the synthesis process. When applied in lithium-ion batteries, the WS2@C structures show higher reversible capacity of 638 mAh g-1 at a current density of 500 mA g-1 and significantly improved cycling stability as compared to the pristine WS2 nanotubes. Post-mortem examinations of the electrode materials reveal that the carbon coatings could preserve the morphology of WS2 nanotubes and assist in forming stable solid electrolyte interface layers, leading to enhanced cycling stability. As such, the WS2@C structures show great potential in the application of lithium-ion batteries for achieving excellent electrochemical performances.
Zhang, J, Sun, B, Zhao, Y, Tkacheva, A, Liu, Z, Yan, K, Guo, X, McDonagh, AM, Shanmukaraj, D, Wang, C, Rojo, T, Armand, M, Peng, Z & Wang, G 2019, 'A versatile functionalized ionic liquid to boost the solution-mediated performances of lithium-oxygen batteries', NATURE COMMUNICATIONS, vol. 10.
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Zhao, D, Chen, Z, Yang, W, Liu, S, Zhang, X, Yu, Y, Cheong, W-C, Zheng, L, Ren, F, Ying, G, Cao, X, Wang, D, Peng, Q, Wang, G & Chen, C 2019, 'MXene (Ti3C2) Vacancy-Confined Single-Atom Catalyst for Efficient Functionalization of CO2', JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, vol. 141, no. 9, pp. 4086-4093.
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Zhao, S, Yan, K, Munroe, P, Sun, B & Wang, G 2019, 'Construction of Hierarchical K1.39Mn3O6 Spheres via AlF3 Coating for High-Performance Potassium-Ion Batteries', ADVANCED ENERGY MATERIALS, vol. 9, no. 10.
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Zhao, Y, Wang, S, Liu, H, Guo, X, Zeng, X, Wu, W, Zhang, J & Wang, G 2019, 'Porous Mo 2 C nanorods as an efficient catalyst for the hydrogen evolution reaction', Journal of Physics and Chemistry of Solids, vol. 132, pp. 230-235.
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© 2019 Elsevier Ltd Generate hydrogen fuel from electrochemical water splitting has been considered as a promising approach. However, to obtain the low-cost and high performance catalysts towards hydrogen evolution reaction (HER)which can be applied in both alkaline and acid solution remains a challenge. Herein, we synthesized an active and stable HER catalyst composed of Mo 2 C nanocrystals embedded in the nanocarbon layers (Mo 2 C@C)by using MoO 3 nanorods as precursor. Benefiting from the porous one dimensional structure and ultrafine Mo 2 C nanocrystals, Mo 2 C@C exhibits high HER catalytic activity for 10 mA cm −2 with the overpotential of 119 mV in 1 M KOH solution and 170 mV in 0.5 M H 2 SO 4 solution, respectively. Moreover, Mo 2 C@C displays long durability during the HER process with almost no decay and maintains the porous one dimensional architecture after the HER stability test. This study offers the guideline for the further design and fabrication of the nanostructured HER electrocatalysts in wide pH range.
Zhou, D, Tkacheva, A, Tang, X, Sun, B, Shanmukaraj, D, Li, P, Zhang, F, Armand, M & Wang, G 2019, 'Stable Conversion Chemistry-Based Lithium Metal Batteries Enabled by Hierarchical Multifunctional Polymer Electrolytes with Near-Single Ion Conduction', ANGEWANDTE CHEMIE-INTERNATIONAL EDITION, vol. 58, no. 18, pp. 6001-6006.
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Zhu, G, Liu, X, Li, L, Chen, H, Tong, W & Zhu, J 2019, 'Cooling System Design of a High-Speed PMSM Based on a Coupled Fluidic-Thermal Model', IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY, vol. 29, no. 2.
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