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 1052 for “"high efficiency"”.
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High efficiency thermophotovoltaic microgenerators
… (1000{1200°C) microburner coupled to a high emissivity, high selectivity PhC selective emitter and low bandgap TPV cells. The PhC emitter and low bandgap cells minimize total microgenerator mass by enabling simultaneous high eciency and high power density, even at moderate temperatures …
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High efficiency gas-solid chromatographic columns
A study of two types of high efficiency gas chromatographic columns was conducted. The first type (micropacked) can be defined as columns having an internal diameter less than 1 mm and a particle/column diameter ratio between 0.1 and O.3 and a packing density comparable to conventional packed …
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High-efficiency Transformerless PV Inverter Circuits
… converter is the most essential part for the efficiency and function performance. In recent years, there have been quite a few new transformerless PV inverters topologies, which eliminate the traditional line frequency transformers to achieve lower cost and higher efficiency, and maintain …
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Signal conditioning for high efficiency : wireless transmission
… wider band-width channels and improved spectrum efficiency to achieve the specified LTE-advanced 100Mbps (mobile) and 1Gbps (fixed) wireless transmission target rate. The next generation of wireless basestations will also need to be powered from renewable sources, particularly in developing …
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Spectrum management for high efficiency photonic devices
Spectrum management holds great promise for high-performance photonics devices. Optical elements that split, up- or down-convert the available light to a specified spectrum can result in higher efficiencies in various devices such as photovoltaic cells, photodetectors, and electronic displays. In …
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High Efficiency Topologies for Dual Voltage Inputs
… to update their policies to require better efficiency in appliance power supplies. Additionally, consumer demand and economic drives in the last few decades have reduced the power supply cost and size. Another emerging trend in recent years is creating a single power supply design that can …
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Towards a high-efficiency micro-thermophotovoltaic generator
Hydrocarbon fuels have such a high energy density that even a relatively inefficient converter of chemical energy into electrical can significantly exceed the energy density of state- of-the-art batteries. This work attempts to do exactly this on a millimeter scale by means of thermophotovoltaic …
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Techniques for high-efficiency outphasing power amplifiers
A trade-off between linearity and efficiency exists in conventional power amplifiers (PAs). The outphase amplifying concept overcomes this trade-off by enabling the use of high efficiency, non-linear power amplifiers for linear amplification. However, the efficiency improvement is limited by the …
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Designing a high-efficiency hydrostatic bicycle transmission
… designed and built in an attempt to measure the efficiency of these devices at approximate cycling speeds. A theoretical model was also developed to help predict losses using a wider range of operational parameters. Due to shortcomings of the experiment design, the measured efficiencies were on …
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Development of a high efficiency dilute gasoline engine
Development of a High Efficiency Dilute Gasoline Engine (HEDGE) and control system for use in the Challenge X design competition encompasses the body of this work. The HEDGE concept embodies running an engine on gasoline at Diesel-like compression ratios. This is accomplished through extreme …
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High Slew Rate High-efficiency Dc-dc Converter
… proposed to improve VR transient response at high slew rate load, which engages in transient periods operating in MHZ to inject high slew rate current in step up load and recovers energy in step down load. Main VR operates in low switching frequency mainly providing DC current. Parallel ATVC …
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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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GreenMap: MapReduce with ultra-high-efficiency power delivery
… work in green computing has focused on improving efficiency for computation units such as CPU’s or servers, little attention has been paid to power delivery structures, such as voltage converters, which takes 10-20% of total energy consumption even before any computation takes place. Recently, a …
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Circuit implementations for high-efficiency video coding tools
High-Efficiency Video Coding (HEVC) is planned to be the successor video standard to the popular Advanced Video Coding (H.264/AVC) with a targeted 2x improvement in compression at the same quality. This improvement comes at the cost of increased complexity through the addition of new coding tools …
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Development of a high-efficiency solar micro-inverter
… are connected to the grid through a single high-power inverter. However, an alternative approach is to connect each solar module directly to the grid through a micro-inverter. This approach makes the system robust to single module failures and results in better power tracking. This project …
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High efficiency photodetection below the quantum noise limit
Two low-noise, high quantum efficiency, high bandwidth photodetectors have constructed to form a balanced homodyne detector to detect squeezed light. The detectors have quantum efficiencies of 85% and 90%, a bandwidth of 1MHz, and a dark noise of ... at 1MHz.
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High efficiency pulse motor drive for robotic propulsion
The goal of this research is to improve the power efficiency of robotic locomotion through the use of series elastic actuation, with a focus on swimming motion. To achieve high efficiency, electromechanical drives need to be actuated at high speed and low torque. However, in many robots, the drives …
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Investigations of a potential high-efficiency thermoelectric generator
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1996.
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