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 20 of 28 for “"beam pattern"”.
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A beam pattern design procedure for multidimensional sonar arrays employing minimum variance beamforming
This paper develops a beam pattern design procedure for general multidimensional irregular sonar arrays that incorporates the not well understood effects of array geometry into the design process. The procedure is implemented by generating a "penalty function" in a spectral covariance function …
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Surface-emitting distributed feedback terahertz quantum-cascade phase-locked laser arrays
A new approach to achieve high-power, symmetric beam-pattern, single-mode THz emission from metal-metal waveguide quantum-cascade laser is proposed and implemented. Several surface-emitting distributed feedback terahertz lasers are coupled through the connection phase sectors between them. Through …
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Evaluation of Discomfort Glare and Pavement Marking Material Visibility for Eleven Headlamp Configurations
… the study. Two baseline conditions, halogen low beam (HLB) and high-intensity discharge (HID) were measured both individually and in combination with three levels of UV-A. In addition, three other headlamp configurations were evaluated. Discomfort glare was measured subjectively for each headlamp …
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Self-Optimizing Metamaterial Antennas
… most promising attribute is software-controlled beam steering - this antenna does not require moving parts and is still able to receive or transmit data without interruption to a moving, non-geosynchronous satellite (for example, a satellite in low Earth orbit, medium Earth orbit, or highly …
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Optimization of transmit/receive array topology in 3D acoustic imaging
… as well as simple transmit and receive array beam patterns reveals desirable beam pattern properties that can be achieved with very dense arrays. As high element numbers in acoustic arrays are cumbersome with respect to manufacture and signal processing, techniques for reduction of array …
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Optical Three-Dimensional Image Matching Using Holographic Information
… techniques of matched 3-D objects for optical pattern recognition. We first describe the 3-D matching technique based on two-pupil optical heterodyne scanning. A hologram of the 3-D reference object is first created and then represented as one pupil function with the other pupil function being …
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Latency Study and System Design Guidelines for Cooperative LTE-DSRC Vehicle-to-Everything (V2X) Communications including Smart Antenna
… can perform dynamical appropriate azimuth pattern by having different weights of each element. The later section includes (1) identifying beam pattern parameters based on locations of a vehicular transmitter and fixed receivers and (2) an approach to find weights of each element of linear …
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Optimal linear array heading in a directional noise field
… heading of the array centers the ambiguous beam of the array at a different true bearing. Therefore, each heading of the array will receive a different ambient noise level. An optimal heading can be obtained which maximizes the SNR received by the array. For all possible headings the beam …
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Learning-Based Control for Optically Trapped Non-Spherical Particles
… near the focal point of a sharply focused laser beam. Since the inception of optical trapping in 1986, it has enabled many scientific discoveries at the small scale. Many optical trapping applications involve trapping spherical objects such as cells or spherical beads attached as handles to …
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Analysis of Quasi-Optical Components for Far-Infrared Astronomy
… known as CST. They were used to predict the beam pattern of corrugated horns including the effects of likely manufacturing errors. NUI Maynooth's Vector Network Analyser was used to confirm the results obtained by the simulations. The results in this thesis show that variations in corrugated …
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Digital projection photochemical etching for gray-scale semiconductor applications
… to focus a substantially de-magnified image beam pattern onto the semiconductor sample, where the projected image itself is used to catalyze and define the etching. The discussion begins with a thorough introduction and literature review to cover the fundamental mechanisms behind the …
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Analysis of 2-axis pencil beam sonar microbathymetric measurements of mine burial at the Martha's Vineyard Coastal Observatory
… 16 total object investigation. A 2-axis pencil beam sonar was deployed concurrently with the mine to obtain microbathymetric measurements of the scour pit development and the progression of mine burial. Data correction techniques to correct for beam pattern induced bathymetry errors and a …
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Collision Avoidance Using a Low-Cost Forward-Looking Sonar for Small AUVs
… sonar system with a limited number of beams. We describe a high-fidelity sonar model and simulation environment that was developed to aid in the design of the sonar system. The simulator achieves real-time visualization through ray tracing and approximation, and can be used to assess …
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Design and implementation of a dual polarised L-band parabolic dish antenna for NeXtRAD
… of the return loss, cross polarisation, gain, beamwidth and beam pattern of the antenna in both planes of polarisation. These results have been recorded, analysed and compared to those found through simulations.
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New frontiers in THz quantum cascade lasers
… power levels sufficient for real-time imaging of beam pattern and fast spectral measurements without requiring expensive cryogenically cooled detectors. The combination of TEC-cooled THz QCLs with room-temperature cameras and detectors enables portable systems that are operable outside the …
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Analysis of 2-axis pencil beam sonar microbathymetric measurements of mine burial at the Martha’s Vineyard Coastal Observatory
… 16 total object investigation. A 2-axis pencil beam sonar was deployed concurrently with the mine to obtain microbathymetric measurements of the scour pit development and the progression of mine burial. Data correction techniques to correct for beam pattern induced bathymetry errors and a …
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Analysis of 2-axis pencil beam sonar microbathymetric measurements of mine burial at the Martha's Vineyard Coastal Observatory
… 16 total object investigation. A 2-axis pencil beam sonar was deployed concurrently with the mine to obtain microbathymetric measurements of the scour pit development and the progression of mine burial. Data correction techniques to correct for beam pattern induced bathymetry errors and a …
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A Prototype Platform for Array Feed Development
… efficiency was measured at 64%, but adaptive beamformers can slightly perturb this value through distortions in the beam pattern. This phenomenon, called pattern rumble, effectively reduced the sensitivity of the radio telescope, and was measured by comparing the SNRs of adaptive beamformers …
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Integrated broadband microphotonic beamformer for adaptive nulling in smart antennas
… arrays capable of adaptively adjusting the beam pattern, thereby enhancing the desired signals (beam steering) and suppressing the interference signals (null steering), which is also known as Space Division Multiple Access (SDMA). SDMA systems allow significant improvement in the area of …
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Composite Right-Left Handed Stripline Structures for Antenna Array Feed Networks
… and possible reduction of radiating beam pattern distortions.</p> <p>A via-less composite right/left-handed stripline unit cell is introduced as an option to attain right/left-handed performance in stripline with a via-less fabrication process that is not sensitive to drill …
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