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 1203 for “"high power"”.
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High-power fibre lasers
This thesis reports on the experimental study of high-power, high-energy, cladding-pumped, rare-earth (Yb3+, Er3+/Yb3+)-doped fibre lasers. Some of the main capabilities of fibre lasers such as: High brightness and thermal properties were exploited for the development of a variety of continuous …
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High power superluminescent light-emitting diodes
… minimising facet reflectivity. The result is a high-power, directional light source with a broad, smooth emission spectrum. The combination of high-power, high spatial coherence and low temporal coherence initially saw SLEDs used in specialist applications such as sources for fibre-optic …
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Nonlinear oscillations in high power systems
… to investigate on nonlinear phenomena affecting high power systems and on the strategies adopted to model them. In the first chapter the attention is focused on two big areas of high power systems: power electronics and systems/devices used to sustain plasma fusion. Although it is common that …
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High power X-band RF test stand development and high power testing of the CLIC crab cavity
… the development and operation of multiple high power X-band RF test facilities for high gradient acceleration and deflecting structures at CERN, as re-quired for the e+ e- collider research programme CLIC (Compact Linear Collider). Signif-icant improvements to the control system and …
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Wideband high-power transmission line pulse transformers
Geometric transformers are often used in radar and communications systems to transition between signal driving and radiating elements that terminate in significantly different geometries with unity input/output impedance. This work demonstrates the design and construction process of a geometric …
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Stability Analysis of a High-Power Microgrid
… perform the modeling and stability analysis of a high-power microgrid with multiple parallel-and grid connected voltage source converters using the system parameters from the high-power microgrid testbed at the National Center for Reliable Electric Power Transmission (NCREPT) at the University of …
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Modeling optically activated high power semiconductor switches
… electric field observed in the operation of a high power photoconductive semiconductor switch. The model solves the continuity equations for electrons, holes, and traps, the energy equation for the lattice, Poisson's equation, and a circuit equation. Physical effects in the model include …
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Development of a high power density rotor
High specific power electric machines are crucial to enabling electric and hybrid-electric aircraft. In order to meet this need, a high specific power electric machine with an unconventional topology is being developed. The topology creates mechanical challenges including expansion due to high speed, …
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High power wide bandgap cascode switching circuits
Emerging wide bandgap (WBG) power transistors are capable of improving the efficiency of mains voltage power electronic circuits. Several commercial WBG transistors are now available, but all exhibit undesirable gate drive characteristics. The cascode circuit has been suggested as a solution to …
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Anode Materials for High Power Microwave Devices
… energy relates to devices capable of generating highly focused energy sources, including lasers, particle beams and microwaves. Extensive research is continuingly conducted into such devices’ frequency spectrum in order to increase their power levels to develop new applications. However, one area …
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The design of high power ultrasonic transducers
… is to investigate the design and construction of high power ultrasound transducers as well as some of the effects of high power ultrasound. The two design approaches that are researched and applied are the equivalent circuit method and Finite Element Method (FEM). These methods are used in …
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All-semiconductor High Power Mode-locked Laser System
… % clock phase stability for large variations in power, bit rate and optical carrier frequency of the input data and therefore is suitable for applications in ultrafast optical packet switching. All-optical timing synchronization of 180-Gb/s data streams has been demonstrated using a MS-GC DFB …
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Advanced waveguides for high power optical fibre sources
… of wavelength-selective waveguide structures for high-power Nd<sup>3+</sup>- and Yb<sup>3+</sup>-doped fibre lasers. Cladding-pumped high-power fibre lasers based on these novel waveguide designs and operating at desired unconventional wavelengths were investigated through numerical simulations …
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High-power diode-pumped ytterbium-doped fibre-laser
… laser and a Q-switched laser. During this work, highly efficient side launching systems were developed. These allowed coupling of more than 70% of the pump light into the doped fibre and gave as good lasing efficiency as end-pumping system. The pump and the signal were also well separated in two …
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High power high efficiency multiple-beam klystron design
… investigation and optimisation methods used. The high desired efficiency of 80% requires low perveance beams, to achieve the specification output power 20 beams are needed. The choice of cavity used in the interaction structure of a klystron has a large impact on its size and efficiency. To …
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High power ultra-short pulse Quantum-dot lasers
… an external cavity configuration is presented. A high peak power of 17.7 W was generated from the quantum-dot laser as a result of the tapered geometry of the gain section of the laser has led to successful application of such device for two-photon imaging. Dual-wavelength mode-locking is …
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Plasma Dynamics in a High-Power Helicon Source
… (NBIs) will provide most of the heating power by accelerating negative ions to energies of 1 MeV, where they are then neutralised to penetrate the magnetic confinement fields. Negative ions, as opposed to positive ions, are required due to their higher neutralisation efficiency at these …
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