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 30 for “"pulse power"”.
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Polymer Composite Dielectric Materials For Pulse Power Applications
… for high energy density storage systems for pulse power applications. Although electrochemical capacitors offer high energy and power density, their rate capability is limited by mass transfer and faradaic reaction rates - a critical issue for delivering intense pulsed power. Polymer …
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Development of high energy density dielectrics for pulse power applications
<p>"Pulsed power applications require large dielectrics (> 10" diameter and ~0.125 thick) with high breakdown strength (BDS). The presence of porosity and increasing grain size lowers the BDS. Testing conditions such as sample thickness, electrode area, electrode design, and form of applied voltage …
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Design and Implementation of High Efficiency, High Power Density Front-End Converter for High Voltage Capacitor Charger
Pulse power system is widely used for medical, industrial and military applications. The operational principle of the pulse power system is that the energy from the input source is stored in the capacitor bank or superconducting inductive device through a dc-dc converter. Then, when a discharging …
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Local and global SAR constrained large tip angle 3D kT̳-points parallel transmit pulse design at 7 T
… can be mitigated through radio frequency (RF) pulse design with conventional single-channel RF systems, but at the cost of impractically long pulses. Parallel transmit (pTx) systems with multiple independent and simultaneous RF transmit channels achieve transmit field inhomogeneity mitigation …
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Pulsed laser ablation deposition and optical characterization of hexagonal-wurtzite silicon
… and to deposit larger hexagonal crystals, a new pulsed laser ablation system with variable parameters was assembled and tested. Deposition expenments were performed in high vacuum with different laser pulse power. Raman spectroscopy showed that the new system successfully produces …
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Distributed optical-fibre sensors for monitoring mechanical strain and disturbance
… non-linearity was carried out, showing that the pulse power is limited by the need to prevent spectral broadening due to self-phase modulation, which adds noise to the sensor output. <br/><br/>Applying the findings of these investigations, further field trials and laboratory tests were carried …
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Distributed fibre sensing using microwave heterodyne detection of spontaneous Brillouin backscatter
… applications, due to the dependence of both the power and the frequency shift of the scattered radiation on these two quantities. Simultaneous temperature and strain sensing is possible if both the power and frequency shift are measured. Much work has been published which presents either power or …
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An attampt to measure the electron temperature of a Xenon Chloride excimer laser discharge plasma by Thomson scattering
… transverse discharge laser to the short, high power Nd:YAG pulse to within 5 ns. Attempts were made to determine the electron velocity distribution of the discharge plasma of this Xenon Chloride laser using the method of Thomson scattering. The Thomson scattering parameter a was 0.22. A short, …
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Optimization of solvent suppression sequences for NMR analysis of aqueous solutions
… environment, pre-saturation solvent suppression pulse sequences are frequently employed to avoid interference from the overbearing solvent signal. However, these sequences generally require extensive re-adjustment of NMR parameters between samples. For this reason, the EXCEPT (EXponentially …
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Optically Controlled High Power High Speed Wide Band Gap Devices
… the past few years in the areas of wide bandgap power electronics for high speed, high power and high efficiency switches which enable innovative approaches to compact pulse power system design and implementation. In the area of high speed pulse technology, optical techniques are clearly superior …
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Techno-economic modelling and optimization of second life battery packs, with a particular focus on accommodating inhomogeneities and module-to-module variations
… characterization is conducted using Hybrid Pulse Power Characterization (HPPC) tests, with a second-order equivalent circuit model (ECM) achieving a maximum error of 2% and an integrated thermal model with a 15% error. One of the key contributions of this research is the development of a …
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Organic Template-Assisted Synthesis & Characterization of Active Materials for Li-ion Batteries
… interested in adapting the Li-ion battery in the power trains of Plug-in Hybrid Electric Vehicles (PHEV) to improve fuel efficiency. Materials currently used for Li-ion batteries are LiCoO2 (LCO) and graphite—the first materials successfully integrated by Sony into Li-ion batteries. However, due …
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Studies of Spectral Modification in Intense Laser Pulse-Plasma Interactions
Laser pulses propagating through plasma undergo spectral broadening through local energy exchange with driven plasma waves. During propagation, a high power laser pulse drives large amplitude plasma waves, depleting the pulse energy. At the same time, the large amplitude plasma wave provides a …
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Degradation Mechanisms and Applications in Ion Intercalation Materials
… Furthermore, I analyze and design improved pulse diagnostics using hybrid pulse power characterization (HPPC) methods to extract physical microscopic degradation mechanisms from electrode-level responses. Overall, I set up a consistent framework modeling degradation from single particle to …
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The Fundamental Resonant Frequency and Radiation Characteristics of Wide Angle Conical Antennas
Of recent interest for simple compact pulse power systems is the self-resonant wide-angle conical antenna. In its typical application, this antenna will radiate a transient damped sine wave pulse whose center frequency is the fundamental resonant frequency of the antenna. In order to properly …
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Electrochemical Model Based Fault Diagnosis of Lithium Ion Battery
… current input profile extracted from the hybrid pulse power characterization (HPPC) cycle simulation of a hybrid electric vehicle (HEV). A partial differential algebraic equation (PDAE) observer was utilized to obtain the estimated voltage, which was used to generate the residuals. Analysis of …
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An Investigation of Tungsten-Based Z-Pinch Planar Wire Array and Benchmarking Experiments
… primarily carried out on Zebra, the 1.0-1.7 MA pulse power generator located at the University of Nevada, Reno (UNR) Physics Department's Nevada Terawatt Facility (NTF), which creates plasmas with typical radiationemission quantum energies up to 2 MeV. This radiation is studied using an …
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Magnetic Switches as Active Device Replacements for Harsh Environments
This thesis explores the use of the archetypical pulsed power magnetic switching devices in alternative and novel methods. The primary motivator for investigating these applications are for the purpose of simplifying electrohydraulic drill and electrocrushing designs meant for extreme environment …
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Investigation into the use of high-efficiency switched-mode class E power amplifiers for high-dynamic range pulse-mode applications
… is operated in either a continuous wave or a pulsed mode where the transmitter is periodically turned on for a portion of time. These systems commonly use a power amplifier in the transmitter to raise the power level of the transmitted signal to a value sufficient to meet system sensitivity …
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Laser-induced plasmas in air for pulsed broadband cavity-enhanced absorption spectroscopy
A pulsed laser-induced plasma (LIP) was generated in ambient air inside a high-finesse near-concentric optical cavity. The broadband optical plasma emission was successfully sustained within the cavity and the light leaking from the cavity was used to measure broadband absorption spectra of gaseous …
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