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 48 for “"Multi-Beam"”.
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Control of a multi-beam antenna using a genetic algorithm
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1995.
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Multi-beam Antenna Arrays for Base Stations in Cellular Communication Systems
Multi-beam antennas will play an increasingly important role in future communications systems such as the fifth generation (5G) and sixth generation cellular systems. There will also be a shift to higher frequencies where more spectrum is available to accommodate wide-band high data rate systems. …
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Multi-wavelength, multi-beam, photonic based sensor for object discrimination and positioning
… is much more sensitive to vibrations than a multi-beam stationary optic approach. Mirror device scanners are slow, bulky and expensive and being inherently mechanical they wear out as a result of acceleration, cause deflection errors and require regular calibration. Multi-wavelength laser …
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Multi-view microscopy and multi-beam manipulation for high-resolution optical imaging
… provide high and isotropic resolution. In the Multi Imaging AxisMicroscope (MIAM) four objective lenses are used to both image the sample and to manipulate it with optical forces. The Selective Plane Illumination Microscope (SPIM) is especially well suited for large biological samples and …
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Fabrication of Novel Three-Dimensional Photonic Crystals Using Multi-Beam Interference Lithography
… an interference lithography experiment. A four-beam setup with beams originating in opposite hemispheres and linear polarizations is found to generate a structure with diamond symmetry and a large complete photonic band gap. Band gap studies on structures that possess both high band gap and high …
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Resolution improvement in optical microscopy by use of multi-beam interferometric illumination
… light patterns generated by interference of multiple coherent beams that converge in a cone. The corresponding sequence of brightness values, measured by a single photodetector (e.g., a single pixel of a CCD), encodes the target's sub-pixel contrast pattern. Fourier domain components at …
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Beamforming and scan pattern performance evaluation of rotating maritime multi-beam phased array surveillance radar
… to test and evaluate the effect of different beamforming and scan patterns on the detection performance of different possible targets in the maritime environment per antenna rotation. MATLAB, with various Phased Array Toolbox objects, was used as the platform to create the simulation model. A …
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A Scheme for Ultra-Fast Computed Tomography Based on Stationary Multi-Beam X-ray Sources
… blurring and radiation dose. The conceptual multi-source interior CT scheme has provided a potential solution to reduce motion artifacts and radiation exposure. This dissertation work conducted multi-facet investigations on a novel multi-source interior CT architecture (G. Cao, et. al, IEEE …
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Image reconstruction and imaging configuration optimization with a novel nanotechnology enabled breast tomosynthesis multi-beam X-ray system
… and imaging configuration for a new multi-beam parallel digital breast tomosynthesis prototype system. Several commonly used algorithms from the typical image reconstruction models which were used for iso-centric tomosynthesis systems were investigated for our multi-beam parallel …
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Microwave Radiometer (MWR) Evaluation of Multi-Beam Satellite Antenna Boresight Pointing Using Land-Water Crossings, for the Aquarius/SAC-D Mission
… For this reason, knowledge of the MWR antenna beam footprint geolocation is crucial to mission success. In particular, this thesis addresses an on-orbit validation of the MWR antenna beam pointing, using calculated MWR instantaneous field of view (IFOV) centers, provided in the CONAE L-1B …
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IP Mobile Multicast over Next Generation Satellite Networks. Design and Evaluation of a Seamless Mobility Framework for IP Multicast Communications over a Multi-beam Geostationary Satellite Network
… unrivalled advantages in supporting IP multicast applications. A new generation of satellite systems that support regenerative on-board processors and multiple spot beam technology have opened new possibilities of implementing IP multicast communication over satellites. These new …
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Directional UAV swarming: a network perspective
… swarming from a network perspective. Generally, multiple UAVs could form a swarming network. Each UAV serves as a network node. The links between UAVs are regarded as network data links. In Chapter 2, we will design a novel 2-layer MAC: We will design the upper MAC layer, which supports the …
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Novel Segment Deformable Mirror Based Adaptive Attenuator Used In Wavelength Division Multiplexed Optical Communications Network
In wavelength division multiplexed (WDM) optical communication networks, signals are amplified periodically by optical amplifiers. Since the gain profiles of optical amplifiers are not flat, equalizers are usually used to maintain signal powers at different wavelengths in equal to avoid crosstalk …
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Advanced Design Methodologies and Novel Applications of Reflectarray Antennas
… proposed with low-loss features at infrared. • Multi-beam reflectarray antennas are studied and it is demonstrated that by optimizing the phase of the elements, a desirable multi-beam performance can be achieved using a single-feed. Local and global phase-only optimization techniques have been …
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Analysis and design of linear-to-circular polarising reflector antennas exploiting periodic metallodielectric arrays
… solution to reduce the number of reflectors in multi-beam antennas in single-feed-per beam architectures while providing circular polarisation for the downlink/uplink. The first part of the thesis is concerned with the analysis of single reflector antennas, focusing on their depolarisation …
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Static Metasurfaces Reflectors with Independent & Complete Control of Magnitude & Phase
… in several different surfaces, such as a multi-beam steering surface, capable of directing two different beams of different relative magnitudes and also having different beam-widths. A single beam surface capable of producing a single beam output with varying magnitudes, from almost …
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Rapid remote determination of hydrographic data for modified surf Index calculations and naval applications
… divers, shore-based personnel, sonar (single, multi-beam, and side-scan), and remotely operated vehicles (ROVs).
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Low-Complexity Structured Neural Networks and Their Usage in Image and Signal Processing
… encryption, and also adaptive wideband multi-beam beamforming. The first neural network architecture, named DCTrix-Net, replaces conventional spatial con- volution with highly sparse factorization of the discrete Cosine transform (DCT) complemented by Toeplitz-structured weight …
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Late cenozoic shallow marine diamond placers off the northern Sperrgebiet, Namibia
… geophysical survey data (Sidescan Sonar and Multi-beam Bathymetry), the deposition of diamonds at these sites were modelled in GIS-based reconstructions. The diamond size frequency distribution (SFO) of the Shallow Marine (0 to -30 m) deposits in the study area is similar to the proximal …
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Double-gated field emission arrays
… such as flat panel displays, mass storage and multi-beam electron beam lithography. This project fabricates and characterizes double-gated field emission devices with high aspect ratio. One of the gates extracts the electrons while the second gate focuses the electrons into small spots. High …
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