Physical Sciences and Mathematics Commons^™

Study Of Transport Properties Of Inas Using Monte Carlo Simulation, Satyanadh Gundimada

Electrical & Computer Engineering Theses & Dissertations

The present research is aimed at ascertaining the usefulness of InAs semiconductor material for single photon avalanche photo detectors operating in the Geiger mode at 2 μm wavelengths. InAs is considered as the material suitable for the purpose because of its less bandgap and lower effective mass of the electrons when compared to other semiconductor materials presently in use. Hence, theoretically transient transport properties of bulk InAs are superior and the velocity overshoot phenomena stronger. InAs is a relatively less explored material when compared to other materials like GaAs. The choice of the material is justified with thorough exploration of …

Yet Another Algorithm For Pitch Tracking (Yaapt), Kavita Kasi

Electrical & Computer Engineering Theses & Dissertations

This thesis presents a pitch detection algorithm that is extremely robust for both high quality and telephone speech. The kernel method for this algorithm is the Normalized Cross Correlation (NCCF) reported by David Talkin [16]. Major innovations include: processing of the original acoustic signal and a nonlinearly processed version of the signal to partially restore very weak F0 components; intelligent peak picking to select multiple F0 candidates and assign merit factors; and, incorporation of highly robust pitch contours obtained from smoothed versions of low frequency portions of spectrograms. Dynamic programming is used to find the ''best" pitch track among all …

Development Of An Efficient Ti:Sapphire Laser Transmitter For Atmospheric Ozone Lidar Measurements, Khaled A. Elsayed

Electrical & Computer Engineering Theses & Dissertations

The impetus of this work was to develop an all solid-state Ti:sapphire laser transmitter to replace the current dye lasers that could provide a potentially compact, robust, and highly reliable laser transmitter for differential absorption lidar measurements of atmospheric ozone. Two compact, high-energy pulsed, and injection-seeded Ti:sapphire lasers operating at a pulse repetition frequency of 30 Hz and wavelengths of 867 nm and 900 nm, with M² of 1.3, have been experimentally demonstrated and compared to model results. The Ti:sapphire lasers have shown the required output beam quality at maximum output pulse energy, 115 mJ at 867 nm and …

Reflection-High Energy Electron Diffraction Study Of Si(100) Homoepitaxy By Femtosecond Pulsed Laser Deposition, Mohammed S. Hegazy

Electrical & Computer Engineering Theses & Dissertations

The dynamics of femtosecond pulsed laser deposition (fsPLD) of Si(!00)-1 x I and Si(!00)-2x I homoepitaxy are studied by in situ reflection high-energy electron diffraction (RHEED) and ex situ atomic force microscopy (AFM). The effects of substrate temperature, laser fluence and the pressure of a passive gas on the Si(!00)-1 x I growth mode are discussed. It is shown that films grow following the Volmer-Weber (3D) growth mode. The substrate temperature largely affects the morphology of the grown film. Below ~ 400 °C (at laser fluence of~ 1.9 J/cm²), randomly oriented 3D clusters are grown. This is shown …

Improvements In Wavelength Modulation Spectroscopy Using Ratios Of Higher Harmonics, James Michael Barrington

Electrical & Computer Engineering Theses & Dissertations

Experiments in Wavelength Modulation Spectroscopy have been conducted at Old Dominion University since 1996. The method provides a highly sensitive, nonintrusive method of probing gases. Research has concentrated on effectively modeling the higher harmonic shapes that are measured experimentally. Accurately modeling these signals will result in the ability to reliably extract the information contained in transition line shapes.

In order to accurately depict the signals, the theory must be thoroughly understood. This thesis develops the theory of Wavelength Modulation Spectroscopy from two aspects: a direct Fourier series expansion of a time varying intensity profile and through communication theory. In addition, …

Embedded Software Programming To Develop A Command Line User Interface For Monitoring And Debugging A Manually Driven Gas Regulator Control System, Syed N. Hyder

Electrical & Computer Engineering Theses & Dissertations

This thesis presents a complete embedded programming model and software codes for a command-line user interface for CONCOA's gas regulator control system. Control Corporation of America (CONCOA) manufactures high-pressure gas regulators, which mechanically control the pressure at their outlets. Since the control system is based on mechanical regulators, adding or stopping gas flow from the system can cause manifold fluctuation that could further cause the pressure to rise or fall with time. The main motivation for developing a command line user interface is to provide a centralized computer control to monitor and debug the gas regulator control system electronically by …

Robust Face Representation And Recognition Under Low Resolution And Difficult Lighting Conditions, Mohammad Moinul Islam

Electrical & Computer Engineering Theses & Dissertations

This dissertation focuses on different aspects of face image analysis for accurate face recognition under low resolution and poor lighting conditions. A novel resolution enhancement technique is proposed for enhancing a low resolution face image into a high resolution image for better visualization and improved feature extraction, especially in a video surveillance environment. This method performs kernel regression and component feature learning in local neighborhood of the face images. It uses directional Fourier phase feature component to adaptively lean the regression kernel based on local covariance to estimate the high resolution image. For each patch in the neighborhood, four directional …

A Formal Object Model For Layered Networks To Support Verification And Simulation, Rasha M. B. E. Morsi

Electrical & Computer Engineering Theses & Dissertations

This work presents an abstract formal model of the interconnection structure of the Open Systems Interconnection Reference Model (OSI-RM) developed using Object-Oriented modeling principles permitting it to serve as a re-usable platform in supporting the development of simulations and formal methods applied to layered network protocols. A simulation of the object model using MODSIM III was developed and Prototype Verification System (PVS) was used to show the applicability of the object model to formal methods by formally specifying and verifying a Global Systems for Mobile communications (GSM) protocol. This application has proved to be successful in two aspects. The first …

Traffic Simulation Using Arena, Shanti Yelamanchi

Electrical & Computer Engineering Theses & Dissertations

Many traffic simulation tools exist for developing traffic simulations; these tools can be divided broadly into two categories — macro simulation tools and micro simulation tools. These two categories of simulation tools are directed at modeling the extremes of traffic systems: very large systems and very small systems. There is a class of intermediate-sized transportation networks for which neither category of simulation tools might perform adequately. Additionally these specialized traffic simulation tools have a high learning curve. For developing medium sized traffic simulations in a short period of time, one might choose to use a familiar general-purpose discrete event simulation …