For airborne radar, there are usually insufficient independent and identically distributed (IID) training data because of geometric considerations and terrain variations. The rank reduction technique is one of the most effective approaches to circumvent this problem. In this study, we investigate four reduced-rank spacetime adaptive detectors for airborne radar, namely, the reduced-rank sample-matrix-inversion (RR-SMI), the reduced-rank adaptive matched filter (RR-AMF), the reduced-rank adaptive coherence estimator (RR-ACE), and the reduced-rank generalized likelihood ratio test (RR-GLRT). Their asymptotic analytical probabilities of detection (PD's) and false alarm (PFA's) are all derived. These detectors all asymptotically attain a constant false alarm rate (CFAR). It is shown that these four reduced-rank detectors exhibit detection performance which is better than or comparable to that of two existing reduced-rank detectors, proposed by Reed and Gau (RG1 and RG2). Moreover, these four reduced-rank detectors are more robust to change in power of clutter and noise than RG1 and RG2.
Abstract-The general principles of design and development of microwave absorbing materials are discussed and analysed in respect to 26-37 GHz frequency range (Ka-band). Dispersive composite materials based on carbon nanotubes in epoxy resin matrix are produced, and their electromagnetic responses are investigated in Ka-band. Both theoretical and experimental results demonstrate that presented composites may be used as compact effective absorbers in 26-37 GHz range.
SUMMARYThe static behaviour of spherical shallow shells bonded with piezoelectric actuators and subjected to electrical loading are studied in this paper by using the di erential quadrature element method (DQEM). Geometrical non-linear e ects are considered. Detailed formulations for the DQ circular spherical shallow shell element and the DQ annular spherical shallow shell element are given for the ÿrst time. Numerical studies are performed to evaluate the e ects of actuator size, thickness and boundary conditions. Very accurate results are obtained by the DQEM. Based on the results reported in this paper, one may conclude that the DQEM is a useful tool for obtaining solutions for smart materials and structures exhibiting geometric non-linear behaviours. Thickness e ects cannot be neglected when the actuator thickness is comparable to that of the base material. Snap-through may occur when the applied voltage reaches a critical value even without mechanical loading for certain geometric conÿgurations.
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