Piccardi, M, Cinotti, TS & Zuffi, S 1995, 'A preliminary performance evaluation of the Quadrics architecture with the DARPA image understanding benchmark' in High-Performance Computing and Networking, Springer Berlin Heidelberg, pp. 124-129.
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Bateman, DG, Mohan, AS, Hay, SG & Bird, TS 1995, 'Method of moments analysis of offset-reflector antennas', Electronics Letters, vol. 31, no. 22, pp. 1889-1890.
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The authors apply the method of moments to analyse the surface currents and radiation patterns of offset-reflector antennas. For a small disk, the convergence of the techniques is compared with an exact solution. The results presented for an offset refle
Cucchiara, R, Distefano, L & Piccardi, M 1995, 'Detection of Circular Objects by Wave Propagation on a Mesh-Connected Computer', Journal of Parallel and Distributed Computing, vol. 31, no. 1, pp. 77-87.
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Circular objects can be detected in low-contrast and/or blurred images by propagating intensity values according to a two-dimensional wave equation and then finding peaks generated by constructive interference. The paper proposes a parallel algorithm for
Guo, YJ 1995, 'Phase efficiency of the reflective array antenna', IEE Proceedings - Microwaves, Antennas and Propagation, vol. 142, no. 2, pp. 115-115.
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Guo, YJ & Barton, S 1995, 'Analysis of one-dimensional zonal reflectors', IEEE Transactions on Antennas and Propagation, vol. 43, no. 4, pp. 385-389.
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A one-dimensional zonal reflector is a conducting surface which is uniform in one direction and has a zonal profile in the other. Similar to a cylindrical reflector, it converts a cylindrical wave from a line-source into an outgoing plane wave. In this paper, the radiation performance of such reflectors with TM-wave illumination is analyzed by the method of moments (MoM). The influence of corner diffraction and zoning on the sidelobe level is investigated. Three types of configurations are considered, which include the parabolic zonal reflector and two stepwise zonal reflectors of different configurations. It is found that corner diffraction makes a significant contribution to the sidelobe level, but zoning intrinsically raises the far-out sidelobes. Numerical results show that the near-in sidelobes of the stepwise zonal reflector can be significantly decreased by adjusting the geometrical configuration. © 1995 IEEE
Guo, YJ & Barton, SK 1995, 'Phase correcting zonal reflector incorporating rings', IEEE Transactions on Antennas and Propagation, vol. 43, no. 4, pp. 350-355.
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An array of Conducting elements printed on a grounded dielectric substrate functions as an electromagnetic phase shifter. With a fixed substrate and a given operating frequency, the phase shift is determined by the array parameters. In the paper, the spectral domain moment method model for analyzing homogeneous reflective phase shifters with conducting rings as elements is presented, and numerical and experimental results are given. A novel phase correcting Fresnel zonal reflector based on this model is reported. A 43% maximum antenna efficiency and -22 dB sidelobe level were measured in X-band. The bandwidth of the reflector is estimated to be greater than 10%. © 1995 IEEE
Piccardi, M, Cinotti, TS & Zuffi, S 1995, 'A preliminary performance evaluation of the Quadrics architecture with the DARPA image understanding benchmark', Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics), vol. 919, pp. 124-129.
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This work presents a preliminary performance evaluation of the Quadrics SIMD massively parallel computer in the execution of a suite of image processing algorithms. The suite is extracted from the low-level and intermediate-level processing sections of the widely-used DARPA Image Understanding benchmark for parallel computers. Implementation issues are briefly described and data partitioning and mapping is addressed. Measurements carried out on two different machine configurations are reported and compared with the performance of other well-known parallel systems.
Simonian, A & Veitch, D 1995, 'A Bene s formula for the fractional Brownian storage'.
Fuente, MP, Guo, YJ, Wilkinson, TA & Barton, SK 1970, 'Direct sequence spread spectrum radio LANs', IEE Colloquium (Digest).
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The performance of direct sequence spread spectrum (DSSS) ISM band Radio Local Area Networks (RLANs) using BPSK modulation and matched filter receivers is investigated. Short and long pseudonoise (PN) spreading sequences, a Barker code and an M- sequence, have been employed in both differential and coherent systems operating in a Rayleigh fading multipath channel with different delay spreads. A channel estimator was designed to perform the system synchronization and control the receiver in order to mitigate the multipath fading and time-dispersion effects by using various multipath diversity techniques. It is found that with low delay spreads the short sequence leads to much better system performance than the long one. It is also shown that use of coherent instead of differential techniques increases the maximum tolerable delay spread.
Gillies, DAG, Johnson, IR, Guo, YJ, Barton, SK & Wilkinson, TA 1970, 'Synchronization techniques for radio LANs', IEE Colloquium (Digest).
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The HIPERLAN system will operate in the 5 GHz and the 17 GHz bands at a data rate of >23.5 Msymbols. Access to the radio medium is assumed to be asynchronous and the medium to be a Rayleigh fading channel. These would need a robust, synchronization mechanism, so that both timing instants in the receiver can be chosen and equalization performed to mitigate the effects of the time dispersive channel. Results show that the codes perform well under moderately severe channel conditions. An optimum 16 bit sequence was selected for appending to the start of frame synchronization sequence to make up for the full 48 bit training sequence. The added sequence preserves the desired correlation function properties of low sidelobes and zero imaginary part.
Guo, YJ & Barton, SK 1970, 'Flat printed lens and reflector antennas', IEE Conference Publication, pp. 253-256.
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The performance of the printed single and double layer phase correcting arrays is theoretically investigated. The latest development of the single printed reflector is also reported. The effective design of a practical size single printed reflector for the reception of direct broadcasting by satellite is discussed, The reflector encompasses three full Fresnel zones and a quarter wave zone, with a 59.4 cm- diameter and 0.8 focal length to diameter ratio. A 43% optimum antenna efficiency and a bandwidth of greater than 10% are determined. The close-in sidelobes of the antenna are around -22dB and the far-out sidelobes are lower than -30dB.
