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 34 for “"50 MHz"”.
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A 50 MHz frequency synthesizer with a 1 Hz resolution
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1988.
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Characteristics of blood vessel wall and atherosclerosis using high frequency ultrasound signals
… and processing techniques for high frequency (50 Mhz) focused ultrasound probe to characterize small tissue specimens such as vessel wall of a few mm thickness. We attempted characterization of normal and atherosclerotic tissue specimens using 50 MHz ultrasound. Techniques for measurement of …
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Very-high-frequency low-voltage power delivery
… operating at very high frequencies (VHF, 30-300 MHz) for low-voltage applications. Contributions include development of a new VHF frequency multiplier inverter suitable for step-down power conversion, and a Si CMOS switched-capacitor step-down rectifier. These are applied to develop a prototype …
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Effect of Nitroxides and Molecular Oxygen on Proton Relaxation Rates in Aqueous Systems and in Lipids
… to proton Larmor frequencies of 0.01 to 50 MHz), as a function of temperature. The resulting data, nuclear magnetic relaxation dispersion (NMRD) profiles, provide insights into mechanisms of relaxation as well as empirical values that relate to a variety of clinical and experimental NMR …
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A High Performance DSP Based System Architecture for Motor Drive Control
… achieves fast speed performance by using the 50 MHz TMS320C25 DSP and specialized digital hardware to perform data acquisition and output control tasks usually performed in software. The peripheral hardware has been designed for easy interface to many types of motor drive systems, to make the …
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Mesospheric wind estimation with the Jicamarca MST radar
… to probe the equatorial mesosphere by scattering 50 MHz pulse transmissions from mesospheric turbulent layers; the pulse returns are detected by the radar antenna and subsequently spectral analyzed. This thesis describes the Jicamarca radar con figuration used for mesospheric Doppler wind …
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Dynamic Element Matching Techniques For Delta-Sigma ADCs With Large Internal Quantizers
… digital path is under 7 ns, thus permitting a 50 MHz clock frequency for the overall ADC.</p>
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NeXtRAD antenna design: X-Band dual polarised conical horn antenna
… include peak power handling of 400 W over a 50 MHz instantaneous bandwidth and the facility to be mounted on a standard tripod. The dissertation begins by introducing NeXtRAD, a radar project developed jointly by UCL and UCT, outlines the objective of the study and lists all the requirements …
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Probing Collective Motions and Hydration Dynamics of Biomolecules by a Wide Range Dielectric Spectroscopy
… based on the complex dielectric response from 50 MHz up to 2 THz by using the system we developed. Comparing these assets of various proteins in different classes helps us shed light on the macromolecular dynamics in a biologically relevant water environment.
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Optimization of a helicon plasma source for maximum density with minimal ion heating
… wave measurements in the range from 100 kHz to 50 MHz are also presented for a wide range of plasma parameters. The data show a clear transition between RF power coupling to the plasma to create density and coupling to heat ions. The transition from plasma production to ion heating indicates …
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Design and implementation of a dual polarised L-band parabolic dish antenna for NeXtRAD
… required to handle a peak power of 1.5 kW over a 50 MHz bandwidth and be able to withstand environmental factors such as wind while mounted on a tripod. This dissertation forms part of the larger NeXtRAD project and as such, the antenna design requirements have been set based on the wider system …
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Electrochemical Synthesis of Soft Magnetic Alloys and Laminates for High Frequency Field Application
… at high frequencies, particularly above 100 MHz. Such design improves the efficiency of power delivery in applications like voltage regulators, MEMS, and digital-to-analog devices. This study outlines the development and fabrication of multilayer laminate and bulk alloys. Using a combination …
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Wideband direct conversion IQ modulators in indium phosphide DHBT technology
… modulation across carrier frequencies from 50 MHz to 26 GHz, a more than 3x increase in bandwidth compared to other IQ modulators covering the cellular band. Chapter 1 of this work provides an introduction to IQ modulation and an overview of the function of the IQ modulator in its target …
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Techniques for low jitter clock multiplication
… measured performance (for a 1.6 GHz output and 50 MHz reference) demonstrated an overall jitter of 0.93 ps rms, and estimated random and deterministic jitter of 0.68 ps rms and 0.76 ps peak-to-peak, respectively. The proposed MDLL architecture is especially suitable for digital ICs, since its …
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Generalized Terminal Modeling of Electro-Magnetic Interference
… The accuracy of the model is confirmed up to 100 MHz in simulation and at least 50 MHz for experimental validation.
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Backscatter and Attenuation Characterization of Ventricular Myocardium
… myocardium. The hearts were interrogated using a 50 MHz transducer that enabled finer spatial resolution than could be achieved at more typical clinical frequencies. Ultrasonic data analyses demonstrated different patterns and relative levels of backscatter and attenuation from the myocardium of …
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Longitudinal impedance of a prototype kicker magnet system
… KAON Factory was measured from 0.3 to 200 MHz using the coaxial wire method. The method consists of transforming the aperture of the kicker magnet under test into a coaxial structure by inserting a central conductor so that the transmission coefficient can be measured. The longitudinal …
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Characteristics of ocean gravity waves off the Cape South West coast
… basis of twice daily spectral measurements at 5 mHz intervals. The wave events, which include generation of swell from near South Georgia, (54°S, 37°W), have been compared with the South African Weather Bureau synoptic charts in order to identify generation centres. Repeated energy values near …
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Attosecond timing jitter modelocked lasers and ultralow phase noise photonic microwave oscillators
… over previous results. Timing jitter of 1 00-MHz Cr:LiSAF lasers is measured with a single-crystal balanced optical cross-correlator to be -30 as from 10 kHz to 50 MHz. Pump intensity noise coupled into phase noise through the self-steepening effect proves to be the major noise source. The …
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