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Full-Text Articles in Engineering
Coupled Electromagnetic And Thermal Analysis And Design Optimization Of Synchronous Electric Machines, Yi Wang
Theses and Dissertations
A new technique for coupling the electromagnetic, thermal, and air-flow analysis is proposed for electronically controlled synchronous machines. A computationally efficient finite element analysis (CE-FEA) technique is employed for the electromagnetic field analysis. An equivalent circuit network is used for thermal and air-flow analysis. An iterative algorithm, which exploits the fact that the type of machines studied have very low rotor losses and also a relatively reduced dependency of core losses with temperature and load, has been developed. The overall computational time is significantly reduced in comparison with the conventional coupling method, such that the new technique is highly suitable …
Coordinated Control Of Power Electronic Converters In An Autonomous Microgrid, Gholamreza Dehnavi
Coordinated Control Of Power Electronic Converters In An Autonomous Microgrid, Gholamreza Dehnavi
Theses and Dissertations
Advances in power electronics and generation technologies have increased the viability of distributed generation systems. A microgrid is a special category of distributed generation systems that is distinguished by its size and the ability to operate independently as an islanded system. As long as a microgrid is connected to a large grid, quality of the voltage is supported by the main grid and each power source connected to the microgrid generates independently. In contrast, in the islanded operation of microgrids and in electrical islands such as shipboard distribution systems, dynamics are strongly dependent on the connected sources and on the …
Doppler-Only Multistatic Radar, Dustin G. Mixon
Doppler-Only Multistatic Radar, Dustin G. Mixon
Theses and Dissertations
In order to estimate the position and velocity of a target, most multistatic radar systems require multiple independent target measurements, such as angle-of-arrival, time-of-arrival, and Doppler information. Though inexpensive and reliable, Doppler-only systems have not been widely implemented due to the inherent nonlinear problem of determining a target’s position and velocity from their measurements. We solve this problem. In particular, we first establish the lack of observability in the Doppler-only bistatic system, thereby demonstrating the need for multiple transmitters and/or receivers. Next, for a multistatic system with a sufficient number of transmitter-receiver pairs, we invoke classical optimization techniques, such as …
A Wire Antenna Designed For Space Wave Radiation Over The Earth Using A Genetic Algorithm, Brian S. Sandlin
A Wire Antenna Designed For Space Wave Radiation Over The Earth Using A Genetic Algorithm, Brian S. Sandlin
Theses and Dissertations
A wire antenna is designed for optimal performance at low elevation angles in the presence of a lossy half-space. A simple genetic algorithm (GA) and GENOCOP III software are each integrated with Numerical Electromagnetics Code Version 4.1 (NEC4.1) to optimize a wire antenna geometry for multiple objectives: power gain, azimuthal symmetry, and input impedance. The performance of the two versions of the integrated GA are compared. Several of the resulting antennas are analyzed, and an antenna is proposed for use in a Remote Intrusion Monitoring System (RIMS). Simulations suggest that the proposed antenna, which is well-matched, offers a significant increase …
Effects Of Near-Field Scatterers On Space-Time Adaptive Processing, Jonathan W. Fitton
Effects Of Near-Field Scatterers On Space-Time Adaptive Processing, Jonathan W. Fitton
Theses and Dissertations
Near-field scatterers, such as the wing of an airplane, can affect the ability of the processor to null out clutter and jammer signals. The target, clutter, and jammer signals will reflect off the near-field scatterers into the array and appear to be coming from a direction different from their true sources. This thesis develops a theoretical model for the direct path and scattered path signals from the target, clutter, and jamming signals. The optimum weight vector, normally computed using the steering vector to the target and the covariance matrix of the undesired signals, must now include the effects of the …
Secondary Data Support And Non-Homogeneities In Space-Time Adaptive Processing, Todd B. Hale
Secondary Data Support And Non-Homogeneities In Space-Time Adaptive Processing, Todd B. Hale
Theses and Dissertations
One of the primary problems with the application of Space-Time Adaptive Processing (STAP) techniques is secondary data support for the interference plus noise covariance matrix estimate. Reed has shown the required secondary data support to achieve performance within 3 dB of optimal SINR is approximately equal to twice the degrees of freedom (DOF) used in the algorithm. Reed proved this rule for Sample Matrix Inversion (SMI) techniques. A concern arises when applying this rule to a newer class of reduced dimension STAP algorithms that do not fall under the SMI umbrella. This thesis focuses on the Cross Spectral Metric (CSM) …