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 21 for “"Total efficiency"”.
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Wireless transfer of electric power
… 60W of power over a distance of 2m with 45% efficiency. In our second experiment, we designed a system which can transfer power from a single source to two devices, each 2m away, with 60% total efficiency. We also developed a quantitative model of our helical resonators which predicted the …
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An Automated Optimal Design of a Fan Blade Using an Integrated CFD/MDO Computer Environment
… as the blade geometry which produces the maximum total efficiency subject to specified constraints on the volume flow rate (CFM) and rotational rate (RPM) of the fan.</p>
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Compact Trench-Based Silicon-on-Insulator Rib Waveguide 90-Degree and 105-Degree Bend and Splitter Design
… size with low loss for different bending angle. Total efficiency is about 92.9% (90 degree bend), 89.3% (105 degree bend), 92% (90 degree splitter) and 84% (90 degree splitter) respectively.
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Scalloped Leading Edge Vaned Diffuser Analysis for a Compact High Pressure Ratio Centrifugal Compressor
… ratios of microturbines leads to low thermal efficiency, which results in very high fuel consumption. Higher operating pressure ratios in microturbines could vastly improve their current fuel efficiency. This thesis focuses on developing a compact, single stage 8:1 pressure ratio centrifugal …
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Syntheses, Structures and Properties of Metal-Organic Frameworks
… powdered activated carbon, which shows increased efficiency when modified with halogen functional groups such as bromine. Metal-organic frameworks (MOFs) have potential applications in mercury capture due to their fantastic properties such as high porosity and high thermal stability. More …
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Hollow Plume Mitigation of a High-Efficiency Multistage Plasma Thruster
… at Thales Electron Devices in Germany. This High Efficiency Multistage Plasma Thruster, or HEMPT, has promising lifetime capabilities due to its plasma confinement system. However, the permanent magnet system that offers this and other benefits also creates a hollow plume, where ions are …
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Testing new potential fuels for ion electrospray propulsion systems
… s) without a statistically significant drop in total efficiency. Future work could include the collection of time of flight data in the negative firing mode, as well as higher precision retarding potential data in both positive and negative polarities. Additional measures could also be taken to …
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Fairness and optimality in trading
… a novel approach to address the issues of efficiency and fairness when multiple portfolios are rebalanced simultaneously. A fund manager who rebalances multiple portfolios needs to not only optimize the total efficiency, i.e., maximize net risk-adjusted return, but also guarantee that …
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Transformer Shielding Technique for Common Mode Noise Reduction in Switch Mode Power Supplies
… are widely used in different applications. High efficiency and high power density are two driving forces for power supply systems. However, high dv/dt and di/dt in switch mode power supplies will cause severe EMI noise issue. In a typical front-end converter, the EMI filter usually occupies 1/3 …
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Divergent Plume Reduction of a High-Efficiency Multistage Plasma Thruster
<p>High Efficiency Multistage Plasma Thrusters (HEMPTs) are a relatively new form of electric propulsion that show promise for use on a variety of missions and have several advantages over their older EP competitors. One such advantage is their long predicted lifetime and minimal wall erosion due …
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Development and simulation of a cylindrical cusped-field thruster and a diagnostics tool for plasma-materials interactions
… of the DCFT. Specifically, the predicted nominal total efficiency ranged from 25 to 35 percent, providing 4-9 mN of thrust at a fixed xenon mass flow rate of 4.0 sccm, whilst consuming 90-400 W of power and with a corresponding nominal specific impulse of 1050 to 1800 s. Preliminary observations …
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Electrospray Thrusters in Chemical-Electric Multimode Propulsion for Small Satellites
… µN, a specific impulse of 600-750 seconds, and a total efficiency of 18-22%, depending on current setpoint. We find that ASCENT is slightly volatile in high vacuum, which causes time-dependent losses in efficiency and specific impulse from gradual propellant evaporation. This volatility may also …
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Flow Interaction Between Turbomachine Blade Row and Flow Resistance Medium
… increases the fan static pressure rise and fan total pressure rise. Regarding energy usage, the fan's total efficiency benefits from the interaction, while static efficiency stays no change because most of the benefit goes to swirl dynamic pressure. The HRM resistance homogeneity study suggests …
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Flow and separation of the oil from compressor discharge to external separator
… has a side effect on the heat transfer and total efficiency. Oil separator is an important component to reduce the amount of oil circulating in the system and to keep the oil in the compressor. Though commonly applied in the industry, oil separator still needs a systematic design guideline. …
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A Unified Turbine Preliminary Design Study
… with fixed cone angle and radius ratio. Both total to static and total to total efficiency was presented as a function of loading coefficient and duty flow coefficient instead of the typically used non dimensional speed and diameter. This was done in order to help aid in the aerodynamic …
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Optimization of an industrial centrifugal blower using gradient-free and gradient-based (adjoint) approaches
… avec pour objectif d’améliorer l’efficacité totale. Les équations de Navier-Stokes en moyenne de Reynolds sont fermées par le modèle SST k − ω pour simuler tous les écoulements turbulents considérés dans cette thèse. La méthode du processus gaussien (GP) conçoit le CB le plus efficace avec …
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On the Evaluation of Common Design Metrics for the Optimization of Non-Axisymmetric Endwall Contours for a 1-stage Turbine Rotor
… modelling, was necessary. Altogether, a total of 8 endwall designs were produced - 6 using a single metric each as the basis of their objective functions (the ‘simple’ designs) and a further 2 so-called ‘compound’ designs. Of the simple designs, the best performing endwalls in terms of …
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INNOVATION AND OPTIMIZATION OF THE HYDROGEN TRANSPORT AND DISTRIBUTION CHAIN AS A GREEN AND RENEWABLE ENERGY VECTOR
… were compared in terms of ohmic resistance, efficiency and energy consumption. Among the Nafion® membranes tested, Nafion® 212 exhibited superior performance due to its lower thickness and higher ion-exchange capacity, resulting in reduced energy consumption. The system maintained high …
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The Turgo impulse turbine : a CFD based approach to the design improvement with experimental validation
… a coarse mesh which slightly under predicts the efficiency but was suitable for comparing designs and a fine mesh which gave mesh independent results. The fine mesh took over 4 times longer to solve rendering it unfeasible for optimisation purposes and it was therefore used only at key points to …
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Design and Analysis of Biomimetic Medusa Robots
… for a multitude of reasons including: efficiency, good room for payload, and a wide range of sizes and morphology. Shape memory alloy (SMA) actuators were selected as the primary source of actuation for the propulsion of the artificial jellyfish node. These actuators offer high power …
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