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 56 for “"Dual-Frequency"”.
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Characterisation of a dual frequency conversion superheterodyne receiver
This dissertation starts off with a brief introduction of the SKA project, and explain how it relates to the KAT project. Then certain receiver design techniques and parameters will be discussed together with receiver design trade-offs will be presented. This dissertation will then focus on the …
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Improved Ionospheric Correction for Dual Frequency and Differential GPS Positioning Methods
… of the gradients was taken into account. The dual frequency correction scheme uses the dispersive nature of the ionosphere to eliminate the ionospheric range error. Nevertheless, the dual frequency model cannot totally remove the effect of the ionosphere as it does introduce some …
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Basis of the theory and interpretation of the dual frequency method
Includes bibliographical references (pages 173-174).
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Wideband and fast THz spectrometer using dual-frequency-comb on CMOS
… gas mixture analysis. Here, a 220-to-320 GHz dual-frequency-comb spectrometer in 65-nm bulk CMOS is presented, along with a systematic analysis on fundamental issues of rotational spectrometer, including the impacts of various noise mechanisms, gas cell, molecular properties, detection …
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A power electronic approach to improved dual-frequency vibration energy harvesting
… harvested power. Previous work demonstrating dual-frequency vibration energy harvesting used a piezoelectric harvester loaded with analog-controlled power electronics but was unable to cancel the parasitic output capacitance typical of piezoelectric harvesters at both frequencies. This thesis …
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Integration and testing of a digital transceiver for a dual frequency, pulse-doppler radar
… of a digital transceiver system for a dual-band, polarimetric radar, which is to form part of the NeXtRAD multistatic radar. NeXtRAD is being developed as an instrument for research into the behaviour of clutter and targets as observed by multistatic radars. The Pentek Cobalt model …
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Development and modeling of a dual-frequency microwave burn rate measurement system for solid rocket propellant
A dual-frequency microwave bum rate measurement system for solid rocket motors has been developed and is described. The system operates in the X-band (8.2-12.4 Ghz) and uses two independent frequencies operating simultaneously to measure the instantaneous bum rate in a solid rocket motor. Modeling …
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Evaluations of microphysical parameterizations in retrieval algorithms for snowfall particle size distributions from dual frequency radar measurements
Dual Frequency Ku and Ka radar measurements from the Global Precipitation Measurement (GPM) satellite have the potential for novel retrievals of snowfall precipitation from space. These retrievals are dependent on assumptions that relate the maximum measured dimension of a snowflake to its mass and …
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Sources of difference frequency sound in a dual-frequency imaging system with implications for monitoring thermal surgery
(cont.) parametric effect, which can be considered an imaging artifact. Additionally, it may be possible to use the nonlinear interaction of scattered waves to form images that rely on the presence of small scatterers; a technique that may be enhanced with the use of contrast agents containing …
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Cross validation of observations from the GPM dual-frequency precipitation radar and dual-polarization S-band ground radars
… Measurement (GPM) Mission Satellite with dual polarization S-Band Ground Radars. The GPM mission is a joint venture by the NASA and the JAXA. The radar on board the core observatory is a dual-frequency precipitation radar (DPR) capable of simultaneously operating at 13.6 GHz (Ku band) and …
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Examining striped bass (Morone saxatilis) predation on hatchery raised Chinook salmon (Oncorhynchus tshawytscha) using dual frequency identification sonar
… to be reducing numbers of Chinook recruitment. Dual-Frequency Identification Sonar (DIDSON) was used to capture video-like images to enumerate and estimate sizes of potential predators in the area. Stomach analysis was used to obtain consumption rate data and a simple model was used to estimate …
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Improving active remote sensing retrievals of snowfall at microwave wavelengths: an emphasis on the global precipitation measurement mission’s dual-frequency precipitation radar
… the Global Precipitation Measurement mission’s Dual-frequency Precipitation Radar (GPM-DPR). Initial evaluations of the retrieval of near-surface snowfall from GPM-DPR against the common global snowfall reference (i.e., CloudSat) showed large discrepancies between the two radar retrieval …
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An Approach For Use of Dual Frequency Identification Sonar (DIDSON) to Quantify Behavioral Aspects of Piscivory at Ecologically Relevant Time and Space Scales
… prey at the scale of meters to tens of meters. Dual- Frequency Identification Sonar, or DIDSON, is a high-resolution acoustic camera operating in the MHz range that provides detailed continuous video-like imaging of objects out to 30 m range. This technology can be used to observe predator-prey …
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An acoustic bubble density measurement technique for surface ship waters
The Dual Frequency Pump Method of acoustically determining point by point bubble cloud densities was studied to determine the practicality of using this acoustic technique to determine bubble densities in surface ship wakes. The dual frequency technique of acoustically detecting bubbles utilizes a …
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Design and characterization of a UHF diplexer/antenna combination
… such functionality. With antennas operating in dual frequency and diplexers which separate the signals, dual-frequency signals can be effectively transferred through the wireless communication systems simultaneously. In this thesis, we simulate and characterize the behavior of antenna and …
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Optimal estimation of ionosphere-induced group delays of global positioning satellite signals during launch, orbit and re-entry
… group delay. In the past, a single-state, dual-frequency filter has been used to estimate the ionospheric delay for authorized users. Although sufficient for terrestrial receivers for which the ionospheric delay changes very slowly, such a filter is inadequate for space-based missions in …
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Limitations and Improvement of Subcarrier Multiplexed Systems over Optical Fiber
… dependent on the fiber dispersion and subcarrier frequency. This power fading is manifested during the direct detection of the subcarrier system using a square-law photodetector. Using a modified optical local oscillator to coherently detect the subcarrier channel this power fading can be …
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Spatial control of cavitation in therapeutic ultrasound
… its near field. In this study, we make use of dual-frequency methods to preferentially lower the cavitation threshold at the focus relative to the rest of the field. One family of dual-frequency driving waveforms is evaluated in a bubble model incorporating rectified diffusion. Theoretical …
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High Birefringence And Low Viscosity Liquid Crystals
… LCs, negative dielectric anisotropic LCs, and dual- frequency LCs. For the positive dielectric anisotropic LCs, we have developed some high birefringence isothiocyanato tolane LC compounds with birefringence ~0.4, and super high birefringence isothiocyanato biphenyl-bistolane LC compounds with …
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