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 36 for “"Low-impedance"”.
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Stable, high-force, low-impedance robotic actuators for human-interactive machines
… aids, must exhibit desired mechanical endpoint impedance while simultaneously producing large forces. In most practical robot configurations, this requires actuators with high force-to-weight ratios and low intrinsic impedance. This thesis explores several approaches to improve the tradeoff …
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A high aspect-ratio silicon substrate-via technology and applications
… microwave and millimeter-wave ICs to provide low impedance ground connections. As silicon RFICs strive for high-frequency operation, it becomes increasingly important to reduce all extrinsic parasitics. Of particular concern is the MOSFET source or BJT emitter impedance, which greatly affects …
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Characterization and analysis of an MRI compatible robot design for wrist psychophysics and rehabilitation
… which drive a non-ferrous, MRI compatible, low impedance hydraulic fluid transmission, consisting of two pairs of custom designed and fabricated vane motors. This thesis details the characterization and redesign of this robot, with emphasis placed upon the hydraulic system.
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Design of Lower Legs of Mithra, a High-Performance Backdrivable Humanoid Robot
… capable of mimicking human movement. A series of low-impedance, high-torque actuator systems were developed with the goal of creating lightweight, powerful, and robust motion. The structure of Mithra's legs mimics the human structure in leg segment length and weight proportions. Detailed design …
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Implementation of viscoelastic Hopkinson bars
… blast or impact events. Testing these soft or low impedance materials using metallic bars in a split Hopkinson pressure bar setup, poor signal to noise ratios and impedance mismatching occur. One solution is to use polymeric Hopkinson bars. In this dissertation, Polycarbonate, Polymethyl …
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Flexible sensors for high-quality recording and human-computer interface
… signals from animals. We have developed low impedance flexible electronic devices for high SNR recording in the motor cortex of rats: With a simple direct sputtering method, we can reduce the impedance of flexible Pt microelectrodes by 5-9-fold and reduce the thermal noise from both in …
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Gallium Nitride phononic crystal resonator
… to transmission line or tethered resonators by allowing a low-impedance path for drive and sense electrodes. GaN resonators are demonstrated with wide-band suppression of spurious modes, f -Q product up to 3.06 x 1012, and resonator coupling coefficient k2.eff up to 0.23%. (filter BW up to 0.46%). …
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Avaliação da estabilidade de tensão em sistemas com elos de corrente contínua em redes eletricamente próximas
… inverter stations interconnected by relatively low impedance.
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A method for characterization of single-event latchup technologies as a function of geometric variation
… bipolar transistors capable of creating low-impedance paths between the power supply rails known as the “latchup” state. Latchup is destructive and requires a power cycle to restore operation. Latchup can be stimulated by ionizing radiation such as a high-energy proton or heavy-ions from …
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A high speed wearable system for body coupled communication
… communication utilizes the inside of the body's low impedance at frequencies on the order of 100 MHz to send signals over that channel and receive the signals at another location on the body. It is also a lower power and more secure wireless option than radio transmission. This thesis presents a …
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Reservoir Delineation Using Bandwidth Extension and Phase Decomposition
… upper slope Niger Delta oil field are commonly below seismic temporal resolution. Although conventional seismic amplitude and amplitude-variation-with-offset are good indicators of oil-filled reservoir rock in this area, they do not necessarily show the vertical distribution of reservoir and may …
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Through-substrate interconnects for 3-D integration and RF systems
… Separately, silicon has been supplanting GaAs in low-end, consumer RF applications. Improving the high-frequency performance of silicon by reducing ground inductance will project silicon technology into high-end RF and mm-wave applications. Furthermore, silicon-based systems allow for integration …
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Design for ESD Reliability in High-Frequency Mixed-Signal Integrated Circuits
… electrostatic discharge (HED) provides a low impedance discharge path for any ESD event. The estimation of maximum PG voltage in digital circuits is critical to determine an optimal topology of protection circuits subject to noise constraints. Experimental results demonstrate the …
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An ankle robot for a modular gait rehabilitation system
… the Newman Lab for Hu- man Rehabilitation uses low impedance robots, such as the MIT-MANUS, to provide assistive therapy in a repeatable and measurable fashion. A system is now being designed to assist gait rehabilitation using a series of lower extremity and pelvis robots that can be used …
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A surface electrode array-based system for functional electrical stimulation
… discomfort associated with stimulation through a low impedance electrode was compared with that experienced during stimulation with a high impedance electrode. The high impedance electrode allowed 9% more current to be passed for an equivalent sensation to that experienced with the low impedance …
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Improvement of Sigma Voltage Regulator - A New Power Architecture
With lower output voltage (lower than 1V) and higher output current (more than 160A) required in the near future, the voltage regulators for the microprocessors, a kind of special power supplies are facing more and more critical challenges to achieve high efficiency and high power density. 90% plus …
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Impedance Characterization and Modeling of Subcellular to Micro-Sized Au, Pt, TiN, and ITO Electrodes With PEDOT:PSS-Coating For Bioelectrical Interfaces
… interfaces with high biocompatibility, low-impedance, and long-term chemical and mechanical stability are of paramount importance in numerous biological and biomedical applications. For meticulous monitoring of biological parameters, there is a rapidly growing interest in sensing at …
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Prototype Of Coupling Unit Network For Power Line Communications
… is inherently unpredictable due to interference, low signaling impedance and the highly linear operating environment that PLC transmitters require. The coupling unit in the PLC system acts as a filter and eliminates the harmful AC signal from interfering with the broadband signals. A coupling unit …
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Electrical Manipulation of Spin Dynamics in Ferromagnetic Multi-layers
… on the simulation-based optimization of the low-impedance microwave resonators fabricated from 80 nm-thick Nb layers on 430 µm thick sapphire substrates and the various coupling effects present in the system. The simulation results are analysed using an equivalent circuit model to extract …
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Advancing the Performance of a Switched-Mode Radio Frequency Power Generation Architecture
… at the operating frequency in order to limit the impedance distortion seen in power combining owing to these parasitics. It is then explored how to best design the combiner to achieve high efficiency at low impedance distortion. The second aspect of the thesis is to develop an interface for the …
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