Digital Commons Network^™

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 …

Free Wake Potential Flow Vortex Wind Turbine Modeling: Advances In Parallel Processing And Integration Of Ground Effects, Nathaniel B. Develder

Masters Theses 1911 - February 2014

Potential flow simulations are a great engineering type, middle-ground approach to modeling complex aerodynamic systems, but quickly become computationally unwieldy for large domains. An N-body problem with N-squared interactions to calculate, this free wake vortex model of a wind turbine is well suited to parallel computation. This thesis discusses general trends in wind turbine modeling, a potential flow model of the rotor of the NREL 5MW reference turbine, various forms of parallel computing, current GPU hardware, and the application of ground effects to the model. In the vicinity of 200,000 points, current GPU hardware was found to be nearly 17 …

Post Hoc Indoor Localization Based On Rss Fingerprint In Wlan, Hao Huang

Masters Theses 1911 - February 2014

In the investigation of crimes committed by wireless users, one of the key goals is to determine the location of the mobile device at the time of the crime. Since this happens during the investigative phase after the crime is committed, we term this the post hoc geographical localization estimation problem. In this thesis, we introduce the post hoc geographical localization estimation problem and present approaches for its solution based on radio frequency (RF) fingerprinting. Motivated by the goal of establishing a crime's location with enough accuracy to obtain a search warrant, our focus is on locating a criminal mobile …

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 …

Towards Accessible, Usable Knowledge Frameworks In Engineering, Jeffrey Mcpherson

Masters Theses 1911 - February 2014

A substantial amount of research has been done in the field of engineering knowledge management, where countless ontologies have been developed for various applications within the engineering community. However, despite the success shown in these research efforts, the techniques have not been adopted by industry. This research aims to uncover the reasons for the slow adoption of engineering knowledge frameworks, namely ontologies, in industry.

There are two projects covered in this thesis. The first project is the development of a cross-domain ontology for the Biomesh Project, which spans the fields of mechanical engineering, biology, and anthropology. The biology community is …

Resource Allocation And Pricing In Virtual Wireless Networks, Xin Chen

Masters Theses 1911 - February 2014

The Internet architecture has proven its success by completely changing people’s lives. However, making significant architecture improvements has become extremely difficult since it requires competing Internet Service Providers to jointly agree. Re- cently, network virtualization has attracted the attention of many researchers as a solution to this ossification problem. A network virtualization environment allows multiple network architectures to coexist on a shared physical resource. However, most previous research has focused on network virtualization in a wired network en- vironment. It is well known that wireless networks have become one of the main access technologies. Due to the probabilistic nature of …

Bi-Directional Vector Variable Gain Amplifier For An X-Band Phased Array Radar Application, Arash Mashayekhi

Masters Theses 1911 - February 2014

This thesis presents the design, layout, and measurements of a bi-directional amplifier with variable vector (in-phase / quadrature) gain control that will be part of an electronically steered phased array system. The electronically steered phased array has many advantages over the conventional mechanically steered antennas including rapid scanning of the beam and adaptively creating nulls in desired locations. The 10-bit bi-directional Vector Variable Gain Amplifier (VVGA) is part of the transmit and receive module of each antenna element where transmit and receive functionality is determined through a simple switch. The VVGA performs amplification of the IF IQ pair by an …