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Articles 1 - 7 of 7
Full-Text Articles in Engineering
Protection And Disturbance Mitigation Of Next Generation Shipboard Power Systems, Marounfa Djibo
Protection And Disturbance Mitigation Of Next Generation Shipboard Power Systems, Marounfa Djibo
Electrical & Computer Engineering Theses & Dissertations
Today, thanks to modern advances mainly in the power electronics field, megawatt-level electric drives and magnetic levitation are being integrated into the marine power grids. These technologies operate based on Direct Current (DC) power which require Alternating Current (AC) to DC conversion within the current grid. Medium-voltage Direct Current (MVDC) and Flywheel Energy Storage Systems (FESS) are the next state-of-the-art technologies that researchers are leaning on to produce, convert, store, and distribute power with improved power quality, reliability, and flexibility. On the other hand, with the extensive integration of high-frequency power electronic converters, system stability analysis and the true system …
Wiener-Fliess Composition Of Formal Power Series: Additive Static Feedback And Shuffle Rational Series, Subbarao Venkatesh Guggilam
Wiener-Fliess Composition Of Formal Power Series: Additive Static Feedback And Shuffle Rational Series, Subbarao Venkatesh Guggilam
Electrical & Computer Engineering Theses & Dissertations
The problem statement for this dissertation is two-fold. The first problem considered is when does a Chen-Fliess series in an additive static feedback connection with a formal static map yield a closed-loop system with a Chen-Fliess series expansion? This work proves that such a closed-loop system always has a Chen-Fliess series representation. Furthermore, an algorithm based on the Hopf algebras for the shuffle group and the dynamic output feedback group is designed to compute the generating series of the closed-loop system. It is proved that the additive static feedback connection preserves local convergence and relative degree, but a counterexample shows …
Enhancing Thermal Stability Of Perovskite Solar Cells With A Polymer Through Grain Boundary Passivation, Tanzila Tasnim Ava
Enhancing Thermal Stability Of Perovskite Solar Cells With A Polymer Through Grain Boundary Passivation, Tanzila Tasnim Ava
Electrical & Computer Engineering Theses & Dissertations
Organic-inorganic halide perovskite solar cells have emerged as a promising photovoltaic technology due to their superb power conversion efficiency (PCE) and very low material costs. While perovskite solar cells are expected to eventually compete with existing silicon-based solar cells on the market, their long-term stability has become a major bottleneck. In particular, perovskite films are found to be very sensitive to external factors such as air, UV light, light soaking, thermal stress and others. Among these stressors, light, oxygen and moisture-induced degradation can be slowed by integrating barrier or interface layers within the device architecture. However, the most representative perovskite …
Security Improvements For The Automatic Identification System, Robert E. Litts
Security Improvements For The Automatic Identification System, Robert E. Litts
Electrical & Computer Engineering Theses & Dissertations
The Automatic Identification System (AIS) is used aboard the vast majority of sea-going vessels in the world as a collision avoidance tool. Currently, the AIS operates without any security features, which make it vulnerable to exploits such as spoofing, hijacking, and replay attacks by malicious parties. This paper examines the work that has been done so far to improve AIS security, as well as the approaches taken on similar problems in the aircraft and vehicular mobile ad-hoc network (MANET) industries. The first major contribution of this paper is the implementation of a Software Defined Radio (SDR) AIS transmitter and receiver …
Electrostatic Design And Characterization Of A 200 Kev Photogun And Wien Spin Rotator, Gabriel G. Palacios Serrano
Electrostatic Design And Characterization Of A 200 Kev Photogun And Wien Spin Rotator, Gabriel G. Palacios Serrano
Electrical & Computer Engineering Theses & Dissertations
High-energy nuclear physics experiments at the Jefferson Lab Continuous Electron Beam Accelerator Facility (CEBAF) require high spin-polarization electron beams produced from strained super-lattice GaAs photocathodes activated to negative electron affinity in a high voltage photogun operating at 130 kV dc. A pair of Wien filter spin rotators in the injector provides precise control of the electron beam polarization at the end station target. An upgrade of the CEBAF injector to better support the upcoming Moller experiment requires increasing the electron beam energy to 200 keV, resulting in better transmission through injector apertures and improved photocathode lifetime. In addition, the energy …
Specification, Control, And Applications Of Z-Source Circuit Breakers For The Protection Of Dc Power Networks, Sagar Bhatta
Specification, Control, And Applications Of Z-Source Circuit Breakers For The Protection Of Dc Power Networks, Sagar Bhatta
Electrical & Computer Engineering Theses & Dissertations
There is a highly-increasing demand for the DC power transmission and distribution in modern power systems for the integration of newly-installed renewable energy resources and storage systems to the existing utilities. Application of DC power systems in electric ships, battery energy devices, high-voltage DC networks, smart grids, electric vehicles, microgrids, and wind farms is a recent trend that is being highly investigated. The fault protection of DC systems is an essential but challenging issue that needs careful attention to maintain system operation reliability and device safety. In this research, the specification, control, and application of Z-source breakers (ZCBs) are investigated …
Commissioning & Characterization Of Magnetized Gridded Thermionic Electron Source, Mark Stefani
Commissioning & Characterization Of Magnetized Gridded Thermionic Electron Source, Mark Stefani
Electrical & Computer Engineering Theses & Dissertations
Collaborative efforts to design and fabricate a magnetized gridded thermionic electron source have been conducted between Xelera and Jefferson Lab. Commissioning and characterization of an electron gun fabricated by Xelera was performed to benchmark the viability of future electron source designs and capabilities. The work involved simulation, installation, trouble-shooting, modifications of the design, commissioning, characterization, and magnetization of the electron beam produced. A specially designed cavity as well as novel diagnostic tools and methods were developed, implemented, and experimentally tested. Finally, the gun was used to demonstrate a previously unachieved current of magnetized electron beam from a gridded thermionic source …