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Articles 1 - 19 of 19
Full-Text Articles in Engineering
Optimal Basis For Ultrasound Rf Apertures: Applications To Real-Time Compression And Beamforming, Sharmin Kibria
Optimal Basis For Ultrasound Rf Apertures: Applications To Real-Time Compression And Beamforming, Sharmin Kibria
Masters Theses 1911 - February 2014
Modern medical ultrasound machines produce enormous amounts of data, as much as several gigabytes/sec in some systems. The challenges of generating, storing, processing and reproducing such voluminous data has motivated researchers to search for a feasible compression scheme for the received ultrasound radio frequency (RF) signals. Most of this work has concentrated on the digitized data available after sampling and A/D conversion. We are interested in the possibility of compression implemented directly on the received analog RF signals; hence, we focus on compression of the set of signals in a single receive aperture. We first investigate the model-free approaches to …
Compressive Parameter Estimation With Emd, Dian Mo
Compressive Parameter Estimation With Emd, Dian Mo
Masters Theses 1911 - February 2014
In recent years, sparsity and compressive sensing have attracted significant attention in parameter estimation tasks, including frequency estimation, delay estimation, and localization. Parametric dictionaries collect signals for a sampling of the parameter space and can yield sparse representations for the signals of interest when the sampling is sufficiently dense. While this dense sampling can lead to high coherence in the dictionary, it is possible to leverage structured sparsity models to prevent highly coherent dictionary elements from appearing simultaneously in a signal representation, alleviating these coherence issues. However, the resulting approaches depend heavily on a careful setting of the maximum allowable …
Integration And Measurements Of A Ka-Band Interferometric Radar In An Airborne Platform, Rockwell B. Schrock
Integration And Measurements Of A Ka-Band Interferometric Radar In An Airborne Platform, Rockwell B. Schrock
Masters Theses 1911 - February 2014
The Topographic Interferometry Mapping Mission (TIMMi) instrument is a unique millimeter wave interferometric radar system operating at 35 GHz (Ka-band). It was constructed in part to advance the technology readiness level of NASA’s Surface Water and Ocean Topography (SWOT) mission, a spaceborne platform that will globally map the altimetry of Earth’s water to gain insight into surface water interactions and dynamics. Previous ground deployments of TIMMi were successful in demonstrating the abilities of the system from a stationary platform. The next logical step was to move TIMMi closer to space by installing it on an airborne platform prove its capability …
Interference Cancellation In Wideband Receivers Using Compressed Sensing, Tejaswi C. Peyyeti
Interference Cancellation In Wideband Receivers Using Compressed Sensing, Tejaswi C. Peyyeti
Masters Theses 1911 - February 2014
Previous approach for narrowband interference cancellation based on compressed sensing (CS) in wideband receivers uses orthogonal projections to project away from the interference. This is not effective in the presence of nonlinear LNA (low noise amplifier) and finite bit ADCs (analog-to-digital converters) due to the fact that the nonidealities present will result in irresolvable intermodulation components and corrupt the signal reconstruction. Cancelling out the interferer before reaching the LNA thus becomes very important. A CS measurement matrix with randomly placed zeros in the frequency domain helps in this regard by removing the effect of interference when the signal measurements are …
Activity Intent Recognition Of The Torso Based On Surface Electromyography And Inertial Measurement Units, Zhe Zhang
Masters Theses 1911 - February 2014
This thesis presents an activity mode intent recognition approach for safe, robust and reliable control of powered backbone exoskeleton. The thesis presents the background and a concept for a powered backbone exoskeleton that would work in parallel with a user. The necessary prerequisites for the thesis are presented, including the collection and processing of surface electromyography signals and inertial sensor data to recognize the user’s activity. The development of activity mode intent recognizer was described based on decision tree classification in order to leverage its computational efficiency. The intent recognizer is a high-level supervisory controller that belongs to a three-level …
Implementation Of Dual-Polarization On An Airborne Scatterometer And Preliminary Data Quality, Jason Dvorsky
Implementation Of Dual-Polarization On An Airborne Scatterometer And Preliminary Data Quality, Jason Dvorsky
Masters Theses 1911 - February 2014
The Imaging Wind and RAin Profiler (IWRAP) is an airborne scatterometer system built and operated by University of Massachusetts Amherst's Microwave Remote Sensing Laboratory (MIRSL). The radar is seasonally deployed aboard one of the two National Oceanic and Atmospheric Administration (NOAA) WP-3D Orion ``Hurricane Hunter'' aircraft based out of MacDill AFB in Tampa, Florida. IWRAP is a dual-frequency, Ku- and C-band, scatterometer that uses two conically scanning antennas to estimate the ocean surface wind vectors as well as intervening rain profiles. Data that is gathered with IWRAP is used to improve current Geophysical Model Functions (GMF) or to help derive …
The Measurement Of Internal Temperature Anomalies In The Body Using Microwave Radiometry And Anatomical Information: Inference Methods And Error Models, Tamara V. Sobers
The Measurement Of Internal Temperature Anomalies In The Body Using Microwave Radiometry And Anatomical Information: Inference Methods And Error Models, Tamara V. Sobers
Masters Theses 1911 - February 2014
The ability to observe temperature variations inside the human body may help in detecting the presence of medical anomalies. Abnormal changes in physiological parameters (such as metabolic and blood perfusion rates) cause localized tissue temperature change. If the anatomical information of an observed tissue region is known, then a nominal temperature profile can be created using the nominal physiological parameters. Temperature-varying radiation emitted from the human body can be captured using microwave radiometry and compared to the expected radiation from nominal temperature profiles to detect anomalies. Microwave radiometry is a passive system with the ability to capture radiation from tissue …
Wireless Physical-Layer Security Performance Of Uwb Systems, Miyong Ko
Wireless Physical-Layer Security Performance Of Uwb Systems, Miyong Ko
Masters Theses 1911 - February 2014
Traditionally, spread-spectrum systems have been employed to provide low probability-of-intercept (LPI) and low probability-of-detection (LPD) performances at the physical layer, but the messages transmitted over such a system are still encrypted with a powerful cipher to protect their secrecy. Our challenge is to find a solution to provide an additional level of security at the physical layer so that simple systems such as RFID tags with limited resources can be secure without using standard encryption. It has recently been suggested that the cryptographic security of the system can be enhanced by exploiting physical properties of UWB signals. With an eavesdropper …
On The Retrieval Of The Beam Transverse Wind Velocity Using Angles Of Arrival From Spatially Separated Light Sources, Shiril Tichkule
On The Retrieval Of The Beam Transverse Wind Velocity Using Angles Of Arrival From Spatially Separated Light Sources, Shiril Tichkule
Masters Theses 1911 - February 2014
For optical propagation through the turbulent atmosphere, the angle of arrival (AOA) cross-correlation function obtained from two spatially separated light sources carries information regarding the transverse wind velocity averaged along the propagation path. Two methods for the retrieval of the beam transverse horizontal wind velocity, v_t, based on the estimation of the time delay to the peak and the slope at zero lag of the AOA cross-correlation function, are presented. Data collected over a two week long experimental campaign conducted at the Boulder Atmospheric Observatory (BAO) site near Erie, CO was analyzed. The RMS difference between 10 s estimates of …
Inversion Of Marine Radar Imagery To Surface Realizations And Dual-Polarization Analysis, Brian Paulsen
Inversion Of Marine Radar Imagery To Surface Realizations And Dual-Polarization Analysis, Brian Paulsen
Masters Theses 1911 - February 2014
The ocean influences global weather patterns, stores and transports heat, and supports entire ecosystems. An area of interest is the relationship between the observed backscattered power received by a surface-based marine radar and the ocean surface topography. Current methods for obtaining surface elevation maps involve either in situ devices, which only provide point measurements, or an interferometric radar, which can be costly. During the late 1990's and early 2000's a radar was built at UMass, called the Focused Phased Array Imaging Radar II (FOPAIR II), and deployed at a several locations. A method is discussed to determine a transfer function …
Addressing/Exploiting Transceiver Imperfections In Wireless Communication Systems, Lihao Wang
Addressing/Exploiting Transceiver Imperfections In Wireless Communication Systems, Lihao Wang
Masters Theses 1911 - February 2014
This thesis consists of two research projects on wireless communication systems. In the first project, we propose a fast inphase and quadrature (I/Q) imbalance compensation technique for the analog quadrature modulators in direct conversion transmitters. The method needs no training sequence, no extra background data gathering process and no prior perfect knowledge of the envelope detector characteristics. In contrast to previous approaches, it uses points from both the linear and predictable nonlinear regions of the envelope detector to hasten convergence. We provide a least mean square (LMS) version and demonstrate that the quadrature modulator compensator converges.
In the second project, …
Automated Detection And Counting Of Pedestrians On An Urban Roadside, Gayatri D. Prabhu
Automated Detection And Counting Of Pedestrians On An Urban Roadside, Gayatri D. Prabhu
Masters Theses 1911 - February 2014
This thesis implements an automated system that counts pedestrians with 85% accuracy. Two approaches have been considered and evaluated in terms of count accuracy, cost and ease of deployment. The first approach employs the Autoscope Solo Terra, a traffic camera which is widely used to monitor vehicular traffic. The Solo Terra supports an image processing-based detector that counts the number of objects crossing user-defined areas in the captured image. The count is updated based on the amount of movement across the selected regions. Therefore, a second approach has been considered that uses a histogram of oriented gradients (HoG), an advanced …
Development, Deployment, And Characterization Of A Ku-Band Interferometer, Anthony Swochak
Development, Deployment, And Characterization Of A Ku-Band Interferometer, Anthony Swochak
Masters Theses 1911 - February 2014
Space-borne radar interferometry provides a global vantage point to understand climate change, global weather phenomenon, and other Earth dynamics. For climate change observations, space-borne interferometers can be utilized to relate ocean topography to temperature, thus providing a global map of ocean temperatures. Since the oceans are in constant motion, a single-pass interferometer is needed to successfully make these measurements of ocean height. The feasibility of a single-pass measurement is dependent on the physical size of the instrument, hence it is cheaper and more practical to launch a small, light weight instrument into space. Since instrument size scales inversely with operating …
Calibration Of The Umass Advanced Multi-Frequency Radar, Matthew Mclinden
Calibration Of The Umass Advanced Multi-Frequency Radar, Matthew Mclinden
Masters Theses 1911 - February 2014
The Advanced Multi-Frequency Radar is a three-frequency system designed and built by the University of Massachusetts Microwave Remote Sensing Lab (MIRSL). The radar has three frequencies, Ku-band (13.4 GHz), Ka-band (35.6 GHz), and W-band (94.92GHz). The additional information gained from additional frequencies allows the system to be sensitive to a wide range of atmospheric and precipitation particle sizes, while increasing the ability to derive particle microphysics from radar retrievals.
This thesis details the calibration of data from the Canadian CloudSat/CALIPSO Validation Project (C3VP) held during January 2007 in Ontario, Canada. The calibration used internal calibration path data and was confirmed …
Optical Lithography Simulation Using Wavelet Transform, Rance Rodrigues
Optical Lithography Simulation Using Wavelet Transform, Rance Rodrigues
Masters Theses 1911 - February 2014
Optical lithography is an indispensible step in the process flow of Design for Manufacturability (DFM). Optical lithography simulation is a compute intensive task and simulation performance, or lack thereof can be a determining factor in time to market. Thus, the efficiency of lithography simulation is of paramount importance. Coherent decomposition is a popular simulation technique for aerial imaging simulation. In this thesis, we propose an approximate simulation technique based on the 2D wavelet transform and use a number of optimization methods to further improve polygon edge detection. Results show that the proposed method suffers from an average error of less …
Data Fusion For The Problem Of Protein Sidechain Assignment, Yang Lei
Data Fusion For The Problem Of Protein Sidechain Assignment, Yang Lei
Masters Theses 1911 - February 2014
In this thesis, we study the problem of protein side chain assignment (SCA) given
multiple sources of experimental and modeling data. In particular, the mechanism
of X-ray crystallography (X-ray) is re-examined using Fourier analysis, and a novel
probabilistic model of X-ray is proposed for SCA's decision making. The relationship
between the measurements in X-ray and the desired structure is reformulated in terms
of Discrete Fourier Transform (DFT). The decision making is performed by developing
a new resolution-dependent electron density map (EDM) model and applying
Maximum Likelihood (ML) estimation, which simply reduces to the Least Squares
(LS) solution. Calculation of the …
Information Theoretic Identification And Compensation Of Nonlinear Devices, Sepideh Dolatshahi
Information Theoretic Identification And Compensation Of Nonlinear Devices, Sepideh Dolatshahi
Masters Theses 1911 - February 2014
Breaking the anonymity of different wireless users with the purpose of decreasing internet crime rates is addressed in this thesis by considering radiometric identification techniques.
Minute imperfections and non-idealities in the different transmitter components, especially the inherent nonlinearity in power amplifiers, result in variations in their Volterra series representations which could be utilized as a signature.
For a two user scenario, signal processing algorithms based on generalized likelihood ratio test(GLRT) and the classical likelihood ratio test are introduced and the resulting receiver decision rules and performance curves are presented. These algorithms consider the high signal to noise ratio(SNR) case where …
System Performance Of Absolute Quartz-Crystal Barometers With Sub-Microbar Precision, Ganesh Kumar Subramanian Ananthanarayanan
System Performance Of Absolute Quartz-Crystal Barometers With Sub-Microbar Precision, Ganesh Kumar Subramanian Ananthanarayanan
Masters Theses 1911 - February 2014
In this thesis, the performance of absolute quartz-crystal barometers is presented, and their ability to measure, with sub-microbar precision, atmospheric pressure fluctuations with periods as short as a few seconds is demonstrated. The first observations of ocean-generated atmospheric infrasound with periods of about 5 s and sub-microbar amplitudes, called microbaroms, using single absolute barometers are presented. These barometers can measure microbaroms with amplitudes down to 50 nanobars and the 1-h estimates of microbarom amplitudes calculated from data collected independently with three collocated barometers differed by only a few nanobars. The observed microbaroms have amplitudes between 0.2 microbars and 1 microbar …
Miniaturization Of Microstrip Patch Antennas For Gps Applications, Steven S. Holland
Miniaturization Of Microstrip Patch Antennas For Gps Applications, Steven S. Holland
Masters Theses 1911 - February 2014
The desire to incorporate multiple frequency bands of operation into personal communication devices has led to much research on reducing the size of antennas while maintaining adequate performance. GPS is one such application, where dual frequency operation, bandwidth and circular polarization pose major challenges when using traditional miniaturization techniques. Various loading methods have been studied to reduce the resonant frequency of the antenna – high permittivity dielectric loading, slot loading and cavity loading – while examining their effects on bandwidth and gain. The objective of this thesis is to provide guidelines on what is achievable using these miniaturization methods and …