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Arribot- An Enabler For Studying Mobile Wireless Sensor Networks, Jaymala Suresh Ghadigaonkar Dec 2006

Arribot- An Enabler For Studying Mobile Wireless Sensor Networks, Jaymala Suresh Ghadigaonkar

Electrical Engineering Theses - Archive

The objective of this thesis is to structure a mobile wireless sensor network using low cost, custom made robotic platforms. Over the years, several projects have proved that the performance of a static wireless sensor network (WSN) is greatly enhanced by using mobile WSN for applications like adaptive exploration or in search and rescue missions where the network topology changes with changes in the environment. A low cost, mobile wireless sensor node known as the ARRI BOT has been designed to contribute along with other robotic platforms in structuring an ingenious mobile wireless sensor network (MSWN). The ARRI BOT has …

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Physical Layer And Application Layer Issues Of Wireless Sensor Networks, Lingming Wang Dec 2006

Physical Layer And Application Layer Issues Of Wireless Sensor Networks, Lingming Wang

Electrical Engineering Dissertations - Archive

The potential for collaborative, robust networks of wireless sensors has attracted a great deal of research attention. For the most part, this is due to the compelling applications that wireless sensor networks will enable. Location sensing, environmental observation and surveillance, medical monitoring and a lot other applications are all gaining interest. However, wireless sensor network poses a large number of challenges. Among all, one of the most important challenges is design sensor networks that have long network lifetime, which will become especially difficult due to the energy-constrained nature of the sensor nodes. In this thesis, we focus on physical and …

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Synthesis And Characterization Of Multifunctional Oxides For Force And Gas Sensors, Vaneet Sharma Dec 2006

Synthesis And Characterization Of Multifunctional Oxides For Force And Gas Sensors, Vaneet Sharma

Material Science and Engineering Theses - Archive

In this research work, the piezoresistivity phenomena in multifunctional oxides of La0.8Sr0.2MnO3 (LSMO) and composites of LSMO - (Ce0.12Zr0.88)O2 has been investigated for force and gas sensor applications in harsh environments including automobile and aerospace industry. In these applications, there is a need of material with high mechanical strength with multi sensing capabilities. The inherent sensing capabilities allow the material to be implemented at variety of platforms. Previously, LSMO polycrystalline ceramics have been studied as a cathode material in solid oxide fuel cells (SOFC). Owing to its colossal magnetoresistance properties, this material has also been extensively studied for use in …

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Branch-And-Cut-And-Price Methods For Logistics Problems With Limited Risk, Hee-Su Hwang Dec 2006

Branch-And-Cut-And-Price Methods For Logistics Problems With Limited Risk, Hee-Su Hwang

Industrial, Manufacturing, and Systems Engineering Dissertations - Archive

There exist many uncertainties in a logistics system, such as unknown demand, unsteady fuel cost, machine breakdowns, and accidents to name a few. Logistics management is difficult because logistics managers must solve a global optimization problem, which includes eliminating as much uncertainty as possible, finding effective methods of managing uncertainty, and operating the entire logistics system effectively. To cope with uncertainty, many efforts have been made for vehicle routing problems. On the contrary, traditional ship-scheduling models ignore uncertainty, even in highly volatile markets. We present a set-packing model that limits risk using a quadratic variance constraint. After generating first-order linear …

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Les For Wing Tip Vortex Around An Airfoil, Jiangang Cai Dec 2006

Les For Wing Tip Vortex Around An Airfoil, Jiangang Cai

Mathematics Dissertations - Archive

The wing tip vortex is very important because of its effects on the noise generation, blade/vortex interactions on helicopter blades, propeller cavitations on ships, and other fields. The objective of this work is to use the numerical simulation with high order accuracy and high resolution to investigate the formation and the near field evolution of a wing tip vortex at high Reynolds number. The computational domain includes a rectangular half-wing with a NACA 0012 airfoil section, a rounded wing tip and the surrounding boundaries. The wing has an aspect ratio of 0.75. The angle of attack is 10 degrees. The …

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Fiber Based Non-Linear Excitation Fluorescence Microscopy, Priyanka Amrita Jillella Dec 2006

Fiber Based Non-Linear Excitation Fluorescence Microscopy, Priyanka Amrita Jillella

Bioengineering Theses - Archive

Non-linear excitation fluorescence microscopy is a high resolution, non-invasive biological imaging technique capable of imaging both in vitro and in vivo at the depths of several hundred microns. The goal of the thesis work is to contribute towards a fiber based non-linear excitation fluorescence microscopy system that we plan to build for our lab, which would later on be integrated with the OCT imaging setup and the DIC microscope. This thesis work involves filling in the key components in the microscopy system. These key components are; femtosecond pulse diagnosis, study of dispersion in optical media, dispersion free femtosecond pulse delivery …

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Applications Of Ultra Wideband, Liang-An Wei Nov 2006

Applications Of Ultra Wideband, Liang-An Wei

Electrical Engineering Theses - Archive

Ultra wideband (UWB) is a new wireless communication system. It utilizes transmission signal at wide bandwidths. With wider bandwidth, it can provide for new useful applications. The first chapter in this thesis discusses the features and advantages of the UWB. Chapters 2 and 3 present two proposed UWB applications. Chapter 2 presents the use of UWB in shipping containers. The security of shipping containers is an urgent issue for globally. UWB can provide a solution to secure containers. Our goal is to develop a system to enhance the transmission signals. In comparison with other system designs, our waveguide approach satisfies …

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Simulation And E-Beam Patterning Of Single Electron Transistor, Karan Deep Nov 2006

Simulation And E-Beam Patterning Of Single Electron Transistor, Karan Deep

Electrical Engineering Theses - Archive

Electron beam lithography is gaining widespread use as semiconductor industry. Current optical lithography techniques are limited to resolution of few hundreds of nanometers and suffer from diffraction problems. The focus of this thesis is to pattern single electron transistors (SET) using electron beam lithography on silicon and silicon on insulator (SOI) substrate which can be further processed to form working SET device. We used different types of e-beam resists like UVN 30, PMMA and HSQ to define source, drain and island for SET. We demonstrated the use of RIE and Deep RIE to etch silicon by using resist as etch …

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Thermal Enhancement Of Stacked Dies Using Thermal Vias, Baekyoung Sung Nov 2006

Thermal Enhancement Of Stacked Dies Using Thermal Vias, Baekyoung Sung

Mechanical and Aerospace Engineering Theses - Archive

Following Moore's law, the number of transistors on a die continues to rise and has recently exceeded a billion on high end processors. In light of the convergence of technology, power requirements is becoming a serious concern even on low density interconnect systems such as cellular phones and personal digital assistants. Also, in order to minimize foot prints, the recent trend in packaging is stacking. The stacking, however, creates challenges in cooling and especially if one is to include logic in the stack. The primary heat flow path for stacking is through the substrate and as the number of stacks …

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Phase Locked Loop For Radiation Hardened Environment, Jer-Fu Dennis Wu Nov 2006

Phase Locked Loop For Radiation Hardened Environment, Jer-Fu Dennis Wu

Electrical Engineering Theses - Archive

This thesis describes a Phase Locked Loop (PLL) design for operation within a radiation environment. Specific design architecture and techniques were implemented to help mitigate radiation effects that degrade PLL performance. This thesis presents several elements of a rad-hard PLL that were developed to solve this challenge, such as a very wideband coupling coefficient LC VCO that has a much higher frequency tuning range than conventional varactor based LC VCOs. The PLL consists a Phase and Frequency Detector (PFD), a rail to rail charge pump, a loop filter, the quadrature LC tank Voltage Controlled Oscillator (VCO), a Current Mode Logic …

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Connections: Library News For Library Staff Vol. 3, Issue 11, University Of Texas At Arlington Library Nov 2006

Connections: Library News For Library Staff Vol. 3, Issue 11, University Of Texas At Arlington Library

Connections: Library News for Library Staff

The purpose of Connections was to build community within UTA Library staff by reminding people of upcoming events and dates, introducing new staff members, celebrating a department's achievements, and writing about other items of interest.

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Models And Algorithms To Determine Cerebral Activation Using Near Infrared Spectroscopy, Monica Suresh Allen Nov 2006

Models And Algorithms To Determine Cerebral Activation Using Near Infrared Spectroscopy, Monica Suresh Allen

Electrical Engineering Dissertations - Archive

The specific aims of this dissertation were to develop: (1) Correlations between experimental protocols and oxygenated, deoxygenated, and total hemoglobin concentrations in the brain (2) Mathematical models to associate blood flow and oxygen consumption rate of the activated brain regions with measured hemodynamic changes (3) A phantom that models brain vasculature compliance to validate developed mathematical models in a controlled setup. The primary imaging modality used in the experimentation phase of this research was near infrared spectroscopy. Previously published multimodality measurements were also used to validate the mathematical models. The single compartment Windkessel model was extended to describe flow-volume dynamics …

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Expressions For Bond Stress Of A Tension Splice In Steel Reinforced Concrete, Jkumar Gopalarathnam Oct 2006

Expressions For Bond Stress Of A Tension Splice In Steel Reinforced Concrete, Jkumar Gopalarathnam

Civil Engineering Theses - Archive

The aim of the research is to develop expressions for the bond stress at a tension splice in reinforced concrete. Many experiments have been conducted inorder to ascertain the relationship between appropriate variables and develop an expression to evaluate the bond stress. The scope of this research is to use existing experimental data to establish a relation and develop an expression. Before the preprocessing begins, the data are organized into different categories such as bottom, top and side bars, and bars with transverse reinforcement. The existing experimental data is evaluated for statistical validation. It is then subjected to individual and …

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Connections: Library News For Library Staff Vol. 3, Issue 10, University Of Texas At Arlington Library Oct 2006

Connections: Library News For Library Staff Vol. 3, Issue 10, University Of Texas At Arlington Library

Connections: Library News for Library Staff

The purpose of Connections was to build community within UTA Library staff by reminding people of upcoming events and dates, introducing new staff members, celebrating a department's achievements, and writing about other items of interest.

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Monitoring And Fault Diagnosis Of Multiconverter Power Electronic Systems, Ranjit Jayabalan Sep 2006

Monitoring And Fault Diagnosis Of Multiconverter Power Electronic Systems, Ranjit Jayabalan

Electrical Engineering Dissertations - Archive

Over the recent years the electric loads in automobiles have increased considerably due to advancements in high-power semiconductor based converters. However, with increasing electrical and electrically driven loads, there have been increasing concerns on system reliability. Faults occurring in such application specific solid state converters can lead to fatal consequences as compared to their mechanical counter parts. Thus, it is vital to identify faults in such systems to develop necessary safety techniques and methodologies. Detailed analysis of faults processes has indicated the need to act quickly following a device failure to prevent propagation of faults that may lead to catastrophic …

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Connections: Library News For Library Staff Vol. 3, Issue 9, University Of Texas At Arlington Library Sep 2006

Connections: Library News For Library Staff Vol. 3, Issue 9, University Of Texas At Arlington Library

Connections: Library News for Library Staff

The purpose of Connections was to build community within UTA Library staff by reminding people of upcoming events and dates, introducing new staff members, celebrating a department's achievements, and writing about other items of interest.

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Self-Assembly Of Nanoparticles In Photonic Crystal Cavities For Optoelectronic Devices, Geetha Thiruvengadam Aug 2006

Self-Assembly Of Nanoparticles In Photonic Crystal Cavities For Optoelectronic Devices, Geetha Thiruvengadam

Material Science and Engineering Theses - Archive

Photonic crystals (PhC) offer many advantages in optoelectronics field. The focus of this thesis is to investigate a self assembly process for the formation of thin film based one-dimensional PhC and the integration of nanoparticles with two-dimensional PhC. Nanoparticles like SiO2, TiO2, PolyStyrene, and PbSe (with different surface properties) were subjected to different experiments. Various techniques, such as spin coating, immersion technique, evaporation induced assembly technique, have been carried out by varying parameters like time, temperature, position of the substrate, etc.,. An optimized method for the fabrication of 1D PhC was found to be evaporation induced Self-Assembly method by varying …

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Uncertainty Characterization Of Orbital Debris, Jolanta Matusewicz Aug 2006

Uncertainty Characterization Of Orbital Debris, Jolanta Matusewicz

Mechanical and Aerospace Engineering Theses - Archive

The increase of orbital debris in the low Earth orbit is a concern for the space industry. Spacecraft and satellites are at risk of collision with orbital debris. Collisions can damage sensitive components or result in catastrophic failure. Organizations such as the United States Space Command are responsible for tracking orbital debris using ground based sensor sites located around the world. Orbit determination techniques are used to estimate the position and velocity of the orbit using range, azimuth, and elevation measurements obtained from the sensors. Nine sensors from the Space Surveillance Network are simulated to track a debris object in …

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Analysis And Design Of A Piezoelectric Micro-Actuator, Po-Shiun Chen Aug 2006

Analysis And Design Of A Piezoelectric Micro-Actuator, Po-Shiun Chen

Mechanical and Aerospace Engineering Theses - Archive

Micro-grippers are usually fabricated of silicon using traditional semiconductor manufacturing processes and actuated based on thermal energy input causing their temperature to substantially increase and render unsuitable for certain applications such as biological tissue handling. In this research work, the design of a micro-gripper using piezoelectric ceramics (PZT) is presented as an alternative to silicon based micro gripper. The design procedure utilized ANSYS, a Finite Element Method based software tool to verify simple PZT models and subsequently evaluate the stroke for a family of configurations. The configurations were further explored and optimized considering that the fabrication would be performed using …

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Mems Packaging: Fluxless Soldering And Reliability Assessment, Amit L. Patil Aug 2006

Mems Packaging: Fluxless Soldering And Reliability Assessment, Amit L. Patil

Mechanical and Aerospace Engineering Theses - Archive

This thesis presents process development and reliability assessment of the fluxless packaging of the MEMS devices. This packaging consists of metallized Kovar package with side wall of same material and circular holes for the optical fiber interconnect between the microstructures on the chip and the macro-environment. The back of the MEMS chip and the soldering part of the optical fiber is metallized. A thin solder perform is placed between the chip and the metallized package to attach the chip and a circular solder perform is used to attach the fiber to the metal substrate. The soldering process is fluxless hence …

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Spacecraft Formation Flight: Analysis Of The Perturbed J2-Modified Hill-Clohessy-Wiltshire Equations, Jeffery Scott Ginn Aug 2006

Spacecraft Formation Flight: Analysis Of The Perturbed J2-Modified Hill-Clohessy-Wiltshire Equations, Jeffery Scott Ginn

Mechanical and Aerospace Engineering Theses - Archive

With the recent technological gains made in satellite design and manufacturing, there has been great interest in utilizing a cluster of satellites to perform the same tasks performed by larger satellites. Historically, this has been done utilizing the Clohessy-Wiltshire equations, or the Hill's equations, as a benchmark for understanding the physics of the relative motion between two spacecraft. A variety of different models have been derived and implemented to study the relative motion dynamics since the Hill-Clohessy-Wiltshire (HCW) equations. Some of these models, like the HCW equations, are linearized and have analytical solutions. These models make the underlying physics due …

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Effect Of Crac Location On A Fixed Rack Layout Of A Data Center, Vishwas Bedekar Aug 2006

Effect Of Crac Location On A Fixed Rack Layout Of A Data Center, Vishwas Bedekar

Mechanical and Aerospace Engineering Theses - Archive

Microprocessor driven escalation of thermal management needs has resulted in significant cooling challenges at the data center facility level, which can house thousands and tens of thousands of heat producing processors. Raised floor air ducting is the most common configuration, where chilled air from the air conditioning units is forced into the room via a under floor plenum and through perforated tiles on the floor. The hot air from the racks finds its way to the top of the air conditioning units and is then cooled and blown into the under floor plenum. The temperature at inlet of the racks …

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Preparation And Characterization Of Doped Zinc Oxide, Yogeeswaran Ganesan Aug 2006

Preparation And Characterization Of Doped Zinc Oxide, Yogeeswaran Ganesan

Material Science and Engineering Theses - Archive

Cathodic electrodeposition was used to prepare thin films of ZnO doped with Cd, from oxygenated KCl electrolyte containing ZnCl2 and CdCl2 in various molar ratios ranging from 0 mM to 5.0 mM each. Evidence for doping was obtained from X-ray powder diffraction, diffuse reflectance, chronopotentiometry, and X-ray photoelectron spectroscopy data. The Cd-doped ZnO samples showed a superior photoresponse relative to undoped ZnO. Cadmium- and indium-doped ZnO were prepared by combustion synthesis using CdCl2 and InCl3 as dopant precursors along with zinc nitrate and urea as the combustion mixture. The doped samples were compared and contrasted with undoped ZnO using scanning …

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Characterization Of Cemented And Fiber-Reinforced Rap Aggregate Materials For Base/ Sub-Base Applications, Carlos A. Ordonez Aug 2006

Characterization Of Cemented And Fiber-Reinforced Rap Aggregate Materials For Base/ Sub-Base Applications, Carlos A. Ordonez

Civil Engineering Theses - Archive

The engineering product known as RAP is a bonded base and sub-base material produced by the process of blending crushed recycled construction and demolition waste and debris to specified gradation requirements, and by bonding these with a fine silica Portland cement matrix at optimum moisture for compaction density. RAP has a great potential as an economically, environmentally, and structurally sound alternative to non-bonded materials conventionally used for base/sub-base applications in pavement engineering. The present work is aimed at thoroughly testing the engineering properties of RAP product in order to assess its suitability as a structurally sound and environmentally safe material, …

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Flow Rate Measurement Of In Situ Perfusion Through The Aqueous Humor Outflow Network, Noel Ortiz Lawrence Aug 2006

Flow Rate Measurement Of In Situ Perfusion Through The Aqueous Humor Outflow Network, Noel Ortiz Lawrence

Bioengineering Theses - Archive

A system was developed to measure the instantaneous perfusate flow rate through the aqueous humor outflow network of a human eye, while under constant pressure. The system monitors real-time weight changes of a perfusate reservoir associated with perfusate flow through the aqueous humor outflow network. The recorded weight changes of the reservoir are used as an indicator of flow rates. Methods to determine time and flow rate resolution and to control for evaporation were also developed. The system is capable of measuring flow on a uL/min scale; determined by the following model, which also includes a range of uncertainty (implies …

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Detection Of Sleep Disordered Breathing Using Electroencephalography, Priya Xavier Aug 2006

Detection Of Sleep Disordered Breathing Using Electroencephalography, Priya Xavier

Bioengineering Theses - Archive

This study investigates the application of Electroencephalography (EEG) to detect Sleep disordered breathing (SDB) using power spectral analysis. A preliminary study was performed on 13 subjects (ages: 49.08 ± 8.82) previously diagnosed with OSA. Power spectral analysis was performed and centered on apnea/hypopnea event terminations. The normalized power changes between the frequency bands delta, theta, alpha and sigma were calculated using the Welch Averaging Periodogram method between 10 s of EEG data before the event termination and 10 s of EEG data after event termination. A significant decrease in normalized delta power and a significant increase in normalized theta, alpha …

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Characterization And Feasibility Study Of A Near Infrared Ccd Imager For Monitoring Tumor Hemodynamics, Manan Goel Aug 2006

Characterization And Feasibility Study Of A Near Infrared Ccd Imager For Monitoring Tumor Hemodynamics, Manan Goel

Bioengineering Theses - Archive

Prostate cancer is one of the most common types of cancers diagnosed among North American men. Chemotherapy is generally used to target advanced metastatic prostate cancer. Near infrared spectroscopy (NIRS) has been previously investigated to monitor the hemodynamic changes in rat prostate tumors; however, the previous study with NIRS is limited by its spatial resolution. The goal of this study is to characterize an NIR, CCD imager and to explore the feasibility of using the CCD imager to non-invasively monitor hemodynamic changes in rat prostate tumors during gas intervention. Firstly, studies were conducted to characterize the CCD imager and understand …

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Impact Of A Pre-Combustion Retrofit Device On Vehicular Emissions: A Case Study, Sri Harsha Kanukolanu Aug 2006

Impact Of A Pre-Combustion Retrofit Device On Vehicular Emissions: A Case Study, Sri Harsha Kanukolanu

Civil Engineering Theses - Archive

Vehicular emissions are a major cause of air pollution in the cities worldwide. Increased numbers of vehicles and the vehicle miles traveled by them every year means that the emissions are going to have a detrimental effect on the life and environment of this planet. Various control strategies are employed by the transportation and air quality managers at the state and regional levels to improve the ambient air quality. This research was conducted as part of the North Central Texas Council of Governments' Aftermarket Technology and Fuel Additive Research Program, its effort to make the DFW region's air cleaner. The …

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Effectiveness Of Signal Coordination As An Emission Reduction Measure For Vehicles, Rajashi I. Parikh Aug 2006

Effectiveness Of Signal Coordination As An Emission Reduction Measure For Vehicles, Rajashi I. Parikh

Civil Engineering Theses - Archive

Air Pollution is a significant health and environmental concern. Vehicular emissions are major contributors to many air pollution problems. There is growing interest in reducing carbon dioxide emission because of the alarming increase in the pollution caused by petroleum resulting global warming issue. Various studies have found that U.S vehicles emit half of the CO2 emitted from vehicle all over the world. Dallas Fort Worth is a non-attainment area for ozone and it is required to achieve NAAQS standards by 2010. NOx and VOCs from the automobile are a major precursor of ozone formation in the atmosphere. Traffic signal retiming …

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Assessment Of Soil-Water Retention Properties Of Lime And Cement Treated Clays, Harshavardhan Reddy Thudi Aug 2006

Assessment Of Soil-Water Retention Properties Of Lime And Cement Treated Clays, Harshavardhan Reddy Thudi

Civil Engineering Theses - Archive

The soil-water characteristic curve (SWCC) of unsaturated soils has considerable importance in the analysis of geotechnical engineering problems involving soils that remain under partially saturated conditions throughout any given year. The SWCC reflects the behavior of unsaturated soils with regard to its hydraulic conductivity, shear strength, and volume change behavior. Numerous investigations have been undertaken in recent decades to extend the unsaturated soil mechanics principles into conventional engineering practice. The soil-water characteristic curve (SWCC) has become a widely used experimental means for assessing fundamental properties of unsaturated soils for a wide range of suction values. However, a limited number of …

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