Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 17 of 17 for “"beampattern"”.
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Deep Learning-Driven Modeling of Dynamic Acoustic Sensing in Biommetic Soft Robotic Pinnae
… neural networks capable of predicting the beampattern (acoustic radiation pattern) of a soft-robotic pinna as function of its actuator states. The pinna model geometry is derived from a tomographic scan of the right ear of the greater horseshoe bat (textit{Rhinolophus ferrumequinum}. Three …
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Transmit Signal Design for MIMO Radar and Massive MIMO Channel Estimation
… scheme which trades o waveform diversity for beampattern directivity. Time-division beamforming consists of a linear precoder that provides direct control of the transmit beampattern and is able to form multiple transmit beams in a single pulse. The MIMO receive ambiguity function, which …
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Biodiversity and dynamics of direction finding accuracy in bat biosonar
… distributed over direction and frequency through beampattern functions that have diverse and often complicated geometries. This complexity could be used by the animals to determine the direction of incoming sounds based on spectral signatures. The present study in its first part has investigated …
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Acoustic vector-sensor array performance
… arrays. It characterizes the vector-sensor array beampattern with and without modeling errors, or "mism;atch." It also develops a hybrid Cramer-Rao bound for direction-of-arrival estimation under mismatch. The results are analyzed, compared to Monte-Carlo simulations, and explored for insight.
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Antenna beamforming for infrastructureless wireless networks
… wireless networks. Based on examination of the beampattern for a uniform circular antenna array (UCAA) utilizing beamforming under a constraint on maximum average transmit power, we approximate achievable user data rates as a function of the number of antenna elements, and we examine the …
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Analysis of Bat Biosonar Beampatterns: Biodiversity and Dynamics
… interface between the bat and its environment. Beampatterns describe this interface as joint time-frequency transfer functions which vary across spatial direction. This dissertation considers bat biosonar shape diversity and shape dynamics manifest as beampatterns. In the first part, the …
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Non-Rayleigh scattering by a randomly oriented elongated scatterer
… prolate spheroid that is randomly located in a beampattern are investigated from physics-based principles both analytically and by Monte Carlo methods. This is a direct-path geometry in which reflections from neighboring boundaries are not a factor. The center of the prolate spheroid is assumed …
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Non-Rayleigh scattering by a randomly oriented elongated scatterer
… prolate spheroid that is randomly located in a beampattern are investigated from physics-based principles both analytically and by Monte Carlo methods. This is a direct-path geometry in which reflections from neighboring boundaries are not a factor. The center of the prolate spheroid is assumed …
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Comparison of the Role of Beamwidth in Biological and Engineered Sonar
… 23 engineered sonar systems and from numerical beampattern predictions for 151 emission and reception elements (noseleaves and pinnae) from bat biosonar. Beamwidth data from these sources is compared to the beamwidth of a planar ellipsoidal transducer as a reference. The results show that …
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Foliage Echoes and Sensing in Natural Environments
… leaf density, where the first two determine the beampattern of each leaf. Compared with echoes collected from real trees, the simulation echoes are qualitatively accurate, i.e., they match in waveforms and also first-order statistics. Since the ground truth is known in the model, the three …
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Array Signal Processing for Communications from High Altitude Platforms and Other Applications
… structure is proposed to generate arbitrary beampattern footprints. A vertical antenna array forming ring-shaped cells is shown to improve the coverage performance and reduce system complexity. In the adaptive beamforming scenario, the minimum variance distortionless response (MVDR) …
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Investigation of Dynamic Ultrasound Reception in Bat Biosonar Using a Biomimetic Pinna Model
… pinnae, they were able to reproduce numerical beampattern predictions that have been obtained for deforming horseshoe bat pinnae in a qualitative fashion. The dynamically deformable biomimetic pinna shapes were estimated to increase the sensory encoding capacity of the device by unit[80]{%} …
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Resilient Waveform Design for OFDM-MIMO Communication Systems
… radar poses many advantages including superior beampattern and improvement in SNR gain. We combine this radar architecture with a projection-based algorithm that allows the radar waveform to project onto the null space of the interference channel of MIMO communications system, thus enabling the …
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Interference Mitigation by Reconfigurable Adaptive Antenna Array
… consider the large array thinning for open-loop beampattern synthesis with the goal of achieving a desired pattern. To this end, three iterative soft-thresholding based optimization algorithms are proposed and compared. Third, we discuss the problem of optimum array configuration for enhanced DOA …
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Spectrum Sharing between Radar and Communication Systems
… estimate of target's angle of arrival, and beampattern of radar are studied for performance degradation. The results show minimal degradation in radar performance and reduction in exclusion zones, thus, showing the efficacy of the proposed approach.
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Dynamic Emission Baffle Inspired by Horseshoe Bat Noseleaves
… changes. Narrow outlet produced an isotropic beampattern and concave baffle had a significant time-variant and frequency-variant effect with just a small displacement. All those results cast light on the possible functions of the biological morphology and provided new thoughts on the …
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Machine Learning Approaches for Biosonar Systems: Investigating Dynamic Sensing in Complex Natural Environments
… with 97.8% accuracy, demonstrating that linear beampattern variations survive projection onto random clutter backgrounds. This finding established the foundation for information encoding through morphological diversity. Building on these linear effects, the second component investigated whether …