Open Access. Powered by Scholars. Published by Universities.®

Electrical and Computer Engineering Commons™

Open Access. Powered by Scholars. Published by Universities.®

University of Texas at Arlington

Discipline
Keyword
Publication Year
Publication
Publication Type
File Type

Articles 541 - 570 of 656

Full-Text Articles in Electrical and Computer Engineering

Wireless Devices For Medical Applications, Thermpon Ativanichayaphong Nov 2007

Wireless Devices For Medical Applications, Thermpon Ativanichayaphong

Electrical Engineering Dissertations - Archive

The deployment of medical electronics in healthcare plays a significant role to overcome many problems in disease treatment and diagnosis. For advanced applications, wireless solutions are preferred. The wireless technologies offer a new dimension of therapy or diagnosis, when wires are often bulky, unsafe, uncomfortable or even impossible to be deployed in some circumstances. The wireless communication devices can be categorized into two groups, active and passive, depending on the power sources operating electronics. The active devices draw powers from a battery, while the others harvest powers from external or internal sources. In this work, two medical applications are studied …

Go to article

High Grade Control Of Linear Induction Motor Drives, Haidong Yu Nov 2007

High Grade Control Of Linear Induction Motor Drives, Haidong Yu

Electrical Engineering Dissertations - Archive

Linear induction machines (LIM) have been widely utilized in military, transportation, aerospace due to the impressive advantages such as simple configuration, easy maintenance and high acceleration/deceleration. However, the existence of trailing eddy current effect and magnetic asymmetry effect undermines the expected functionality of vector control even though LIM inherent similarities from its rotary counterpart. As a result, it has been a focal research area to either improve the performance of vector control for LIM or develop a new high grade control strategy. Therefore, the in-depth knowledge of electromagnetic behavior of LIM is necessary. From both finite element analysis (FEA) and …

Go to article

Time-Varying Feedback Systems Design Via Diophantine Equation Order Reduction, Shr-Hua Wu Oct 2007

Time-Varying Feedback Systems Design Via Diophantine Equation Order Reduction, Shr-Hua Wu

Electrical Engineering Dissertations - Archive

Diophantine equation plays an important role in the design and synthesis of feedback compensators. Many methods have been developed to solve the Diophantine equation. This dissertation develops a new systematic approach of solving a linear time-varying Diophantine equation. This approach is based upon successively reducing the order of the Diophantine equation by Euclidean algorithm. Euclidean algorithm for solving for both time-invariant and time-varying Diophantine equations for directly determining both the quotient and the remainder associated with the division of one polynomial by another is presented. The coprimeness (right or left) of two Polynomial Differential Operators is needed to guarantee, in …

Go to article

Medium Access Control(Mac) Layer Design And Data Query Processing For Wireless Sensor Networks, Qingchun Ren Sep 2007

Medium Access Control(Mac) Layer Design And Data Query Processing For Wireless Sensor Networks, Qingchun Ren

Electrical Engineering Dissertations - Archive

In this dissertation, there are four main aspects included: energy reservation on MAC layer, secure improvement for DoS attacks on MAC layer, query processing with uncertainty for sensor database systems, and throughput maximization on MAC layer for ultra wideband communication systems. In energy reservation, we proposed asynchronous MAC (A-MAC) protocol and asynchronous schedule-based MAC (ASMAC) protocol. A-MAC and ASMAC protocols are attractive due to their suitabilities for multihop networks and capabilities of removing accumulative clock-drifts without any network synchronization. Moreover, we build a traffic-strength- and network-density-based model to adjust essential algorithm parameters adaptively. In secure problem, we proposed a secure …

Go to article

Cmos Vco & Lna Implemented By Air-Suspended On-Chip Rf Mems Inductors, Varun K. Shenoy Aug 2007

Cmos Vco & Lna Implemented By Air-Suspended On-Chip Rf Mems Inductors, Varun K. Shenoy

Electrical Engineering Theses - Archive

In this thesis, a CMOS 2.4 GHz Low noise amplifier (LNA) and Voltage-controlled oscillator (VCO) was designed and simulated. These circuits were designed to operate in the 2.4GHz Industrial Scientific Medicine (ISM) band and to achieve Bluetooth and Wifi standard specifications. High-Q RF MEMS air-suspended circular spiral inductors are used in both circuits. High-Q inductors give the circuit better performance parameters including higher gain, lower noise figure and narrower bandwidth. The integration of these RF MEMS inductors onto RF circuit chips was carried out using the UV-LIGA technique and an additive pattern transfer technique such as electroplating. The LNA maintains …

Go to article

Spatially Resolving Spectrometer For Characterisation Of Broad-Area Laser Diodes, Sheldon Fernandes Aug 2007

Spatially Resolving Spectrometer For Characterisation Of Broad-Area Laser Diodes, Sheldon Fernandes

Electrical Engineering Theses - Archive

The mode pattern of the BALD (Broad-Area Laser Diode) is characterized and measured using a 1-GHz resolution double-pass spectrometer. The design of spectrometer allowed also a spatial discrimination with 1mkm resolution. The construction and design of the double-pass grating is analyzed and discussed. A matrix approach is developed for the double-pass measurement arrangement. The developed procedure of analysis of spatially resolved spectra provides unique information about broad-area laser diode active medium and cavity geometry and potentially will help to predict the reliability of the laser diode. The developed model is based on paraxial approximation. The laser diode modes are measured …

Go to article

Fabrication Of A Silicon Single Electron Transistor, Sharukh Roomy Chinoy Aug 2007

Fabrication Of A Silicon Single Electron Transistor, Sharukh Roomy Chinoy

Electrical Engineering Theses - Archive

Single electronics has bright prospects because of its high scalability. The single electron transistor (SET) which utilizes these principles could replace the current workhorse of the industry, the MOSFET. The SET is plagued with limitations such as, a low operating temperature, background charge issues, a low voltage gain and high output impedance. The current generation SET devices have overcome most of the aforementioned issues but use highly complicated fabrication techniques. Electron beam lithography was used to pattern device structures on silicon-on-insulator (SOI) wafers with a hydrogen silsesquioxane (HSQ) system being the resist. The silicon was then etched using HSQ as …

Go to article

A Potential Field Approach To Multiple Robot Formation Control, Rohit Santosh Talati Aug 2007

A Potential Field Approach To Multiple Robot Formation Control, Rohit Santosh Talati

Electrical Engineering Theses - Archive

A special case of cooperative control for mobile robots is considered - formation control. A potential field based algorithm is developed in which geometric, communication and information centric influences are considered and allowed to deform the formation. Control is accomplished in a leader-follower(s) method. One leader robot defines the overall trajectory and follower nodes individually and autonomously maintain the formation while simultaneously moving toward a goal position. The particular nodes considered are the ARRIbots developed at the Distributed and Intelligence and Autonomy Lab (DIAL) in the Automation and Robotic and Research Institute (ARRI), which are non-holonomic differential-drive wheeled robots. In …

Go to article

Discrete Event Controller: Application Using Dynamic Resource Allocation, Abhishek Trivedi Aug 2007

Discrete Event Controller: Application Using Dynamic Resource Allocation, Abhishek Trivedi

Electrical Engineering Theses - Archive

This work consists of developing a Discrete Event Controller with Dynamic Resource Allocation, simulating it and than applying it on a test-bed using robots and static sensor nodes. These are the contributions made: 1. Interfacing the Garcia robot with Mica2/Cricket Sensor. 2. Implementing Obstacle Avoidance and Path planning on Garcia Robot for navigational purposes. 3. Localizing the Garcia Robot with the help of Cricket sensor and controlling it from the Base Station to perform assigned tasks. 4. Simulating a Discrete Event Controller which dynamically coordinates multiple missions and simultaneously performing dynamic resource assignment and solving any shared resource conflicts. 5. …

Go to article

Optimized Class-E Rf Power Amplifier Design In Bulk Cmos, Tao Wang Aug 2007

Optimized Class-E Rf Power Amplifier Design In Bulk Cmos, Tao Wang

Electrical Engineering Theses - Archive

The telecommunication market calls for the integration of complicated wireless applications. To build RF power amplifiers in CMOS remains challenging due to the nonideal effects in CMOS. The aim of this thesis is to provide an optimized yet explicit design method for the Class-E amplifiers in CMOS. Taking the finite DC feed inductor into consideration, a simple but accurate numerical design method is proposed by applying polynomial interpolation. Combining with a practical design stategy for nonideal transistors of finite conductance and parasitic capacitances, a two-staged Class-E power amplifier is implemented in 0.18um CMOS. The simulation results show that this power …

Go to article

Evaluation And Applications Of Gas Sensors, Hung Viet Cao Aug 2007

Evaluation And Applications Of Gas Sensors, Hung Viet Cao

Electrical Engineering Theses - Archive

Gas sensors are used widely for environmental and biomedical uses. This work focuses on verifying specifications of commercial-off-the-shelf (COTS) gas sensors and their particular applications. The first chapter in this thesis gives a literature review on gas sensors, especially metal-oxide based sensors and their advantages. The second chapter focuses on evaluation of COTS NO2 sensors. The purpose is to establish a characterization method to evaluate gas sensors. I have evaluated three COTS metal-oxide based NO2 sensors and a COTS electrochemical sensor for comparison. Four different tests have been implemented to investigate the sensitivity, humidity effects, temperature effects, and selectivity for …

Go to article

Design And Simulation Of An Accurate Breast Biopsy System, Sumit Tandon Aug 2007

Design And Simulation Of An Accurate Breast Biopsy System, Sumit Tandon

Electrical Engineering Theses - Archive

Core needle biopsy is a non-invasive technique for confirming breast and prostate cancer. Over the years, several non-real time image guided systems have been developed to guide the needle to the target lesion/tumor. Frequently used methods are those employing x-ray, ultrasound, MRI or x-ray fluoroscopy to guide the needle during biopsy. However, these methods suffer from the disadvantages that they are non-real time or the imaging technique is two dimensional or ionizing. Our broad objective is to develop a visually guided, haptic assisted breast biopsy system (henceforth called ViHAB) using real time 3D ultrasound imaging and haptic guidance. The system …

Go to article

Polymer-Based Rf Mems Devices, Jianqun Wang Aug 2007

Polymer-Based Rf Mems Devices, Jianqun Wang

Electrical Engineering Dissertations - Archive

The radio frequency micro-electro-mechanical system (RF MEMS) technology is rapidly transitioning from the research stage to commercial applications. Reducing material and fabrication costs, realizing IC compatibility, and improving the RF performance have been main focal points of many recent works. In this dissertation, we target at developing a RF MEMS methodology which realizes CMOS compatibility, cost effectiveness and high performance at the same time. The current RF MEMS devices are mostly constructed on quartz and III-V compound materials to achieve low RF losses. These approaches proved to have excellent RF performance. However these materials are expensive and unable to be …

Go to article

Model Reference Adaptive Control Using Stacked Identifiers, Weider Chung Aug 2007

Model Reference Adaptive Control Using Stacked Identifiers, Weider Chung

Electrical Engineering Dissertations - Archive

Model reference adaptive control is a major design method for controlling plants with uncertain parameters. The primary objective of this dissertation is to develop a new design approach for the model reference adaptive control of a single-input single-output linear time-invariant plant. The proposed method, called the "Model reference adaptive control using stacked identifiers," uses a stacked identifier structure that is new to the field of adaptive control. The goal is to make the output of the plant asymptotically track the output of the first identifier, and then driving the output of the first identifier to track that of the second …

Go to article

1/F Noise In Hafnium Based High-K Gate Dielectric Mosfets And A Review Of Modeling, Siva Prasad Devireddy Aug 2007

1/F Noise In Hafnium Based High-K Gate Dielectric Mosfets And A Review Of Modeling, Siva Prasad Devireddy

Electrical Engineering Dissertations - Archive

For next generation MOSFETs, the constant field scaling rule dictates a reduction in the gate oxide thickness among other parameters. Consequently, gate leakage current becomes a serious issue with very thin SiO2 that is conventionally used as gate dielectric since it is the native oxide for Si substrate. This has driven an industry wide search for suitable alternate 'high-k' gate dielectric that has a high value of relative permittivity compared to SiO2 thereby presenting a physically thicker barrier for tunneling carriers while providing a high gate capacitance. Consequently, it is essential to study the properties of these novel materials and …

Go to article

Sequences Of Near-Optimal Feedforward Neural Networks, Pramod Lakshmi Narasimha Aug 2007

Sequences Of Near-Optimal Feedforward Neural Networks, Pramod Lakshmi Narasimha

Electrical Engineering Dissertations - Archive

In order to facilitate complexity optimization in feedforward networks, several integrated growing and pruning algorithms are developed. First, a growing scheme is reviewed which iteratively adds new hidden units to full-trained networks. Then, a non-heuristic one-pass pruning technique is reviewed, which utilizes orthogonal least squares. Based upon pruning, a one-pass approach is developed for producing the validation error versus network size curve. Then, a combined approach is devised in which grown networks are pruned. As a result, the hidden units are ordered according to their usefulness, and less useful units are eliminated. In several examples, it is shown that networks …

Go to article

Optimization Of Coupling From A Sub-Wavelength Metal Nanoaperture To A Gaussian Mode, Muthiah Annamalai Aug 2007

Optimization Of Coupling From A Sub-Wavelength Metal Nanoaperture To A Gaussian Mode, Muthiah Annamalai

Electrical Engineering Theses - Archive

We model the surface resonance effects in a 1D-array of corrugations on a metal-dielectric film with a sub-wavelength nanoaperture, following the earlier work by Moreno et-al [Moreno:2003]. We are interested in computing the coupling of the highly-directional light field emerging from the metal nanoaperture to the lowest-order Gaussian mode. We follow the approach by Vasilyev [Vasilyev:2005], to compute the coupling to a fundamental Gaussian mode. We have developed an optimization routine to compute the field emission patterns from a metal nanoaperture, resonant wavelength and transmission coupling to fundamental Gaussian mode for various geometrical parameters of the metal nanoastructure. We optimize …

Go to article

Development Of Quality-Aware Video Systems And Nmr Spectrum Registration, Basavaraj Hiremath Jul 2007

Development Of Quality-Aware Video Systems And Nmr Spectrum Registration, Basavaraj Hiremath

Electrical Engineering Theses - Archive

The work introduces a novel concept of Quality-Aware Video (QAV) System and demonstrates its successful implementation. During the course, it develops algorithms for reduced reference video quality assessment and for data hiding. The idea here is to extract quality defining features of the video sequence and embed them in the original video without causing any perceptual changes to obtain QAV. Such a QAV can then be exposed to distortions and adverse attacks that affect the perceptual quality of the video. At the receiving end, the algorithm extracts the quality features of the distorted video, decode the original video quality features, …

Go to article

Modeling Isotropic Organs Using Beam Models For The Haptic Simulation Of Blunt Dissections Of Bile Duct, Vishal Dalmiya Jul 2007

Modeling Isotropic Organs Using Beam Models For The Haptic Simulation Of Blunt Dissections Of Bile Duct, Vishal Dalmiya

Electrical Engineering Theses - Archive

Haptic modeling of organs using existing approaches is still not realistic and/or real time. We propose and develop the mathematical foundation of a new approach to modeling organs using beams. Beams are well known entities in Civil and Structural engineering. We develop their mathematical properties in the context of organ characteristics. The real time advantage arises from the fact that a single beam implementation eliminates hundreds, if not thousands of mass springs from the traditional mass spring models and, thousands of polygons from the finite element method (FEM). Even more importantly, our derivation works for both large and small deflections. …

Go to article

Detection And Opportunistic Spectrum Access In Sensor Networks, Hung Dinh Ly Jul 2007

Detection And Opportunistic Spectrum Access In Sensor Networks, Hung Dinh Ly

Electrical Engineering Theses - Archive

This thesis examines target detection problems in Radar Sensor Networks (RSN) and opportunistic spectrum access problem in Cognitive Sensor Networks (CSN). First, studies on the Space-Time Adaptive Processing (STAP) and radar waveform design are provided. Investigation into the target detection performance gain of RSN when STAP and radar waveform design are combined in RSN is then performed. Studies in this thesis show that detection performance of RSN using our proposal is superior to that of a single radar system using STAP only. To further studies on target detection, the multi-target detection problem in RSN is also examined. Signal, interference, and …

Go to article

Wireless Sensor Network Lifetime Analysis And Energy Efficient Techniques, Haining Shu Jul 2007

Wireless Sensor Network Lifetime Analysis And Energy Efficient Techniques, Haining Shu

Electrical Engineering Dissertations - Archive

Wireless microsensor networks is one of the most important technologies for the 21st century. In distributed sensor networks energy-aware techniques are used to reduce energy consumption. Various sensor network applications have taken energy efficiency into consideration. This thesis report focuses on a new approach based on fuzzy logic systems to analyze the lifetime of a wireless sensor network. It demonstrates that a type-2 fuzzy membership function (MF), i.e., a Gaussian MF with uncertain standard deviation (std) is most appropriate to model a single node lifetime in wireless sensor networks. This research studies two basic sensor placement schemes: square-grid and hex-grid. …

Go to article

Power Control And Multi-Target Identification In Cognitive Wireless Networks, Hong-Sam Thi Le Jul 2007

Power Control And Multi-Target Identification In Cognitive Wireless Networks, Hong-Sam Thi Le

Electrical Engineering Theses - Archive

Recent research results have shown that cognitive wireless networks (CWN) have the potential to alleviate spectrum scarcity problem resulting from current policies for radio resource allocation management and dramatically improve the overall performance of communication systems. Unlike conventional wireless networks, which lack the flexibility and adaptation in their operations, CWNs exploit cognitive radio technology which provides cognitive wireless devices with the ability to sense the situation, adapt to the environment and take appropriate actions correspondingly. There have been many challenges in building a fully functional CWN. New developments and approaches need to be proposed to allow radio users to share …

Go to article

Wireless Sensor Network Testbed: Measurement And Analysis, Rahul Pramod Sawant May 2007

Wireless Sensor Network Testbed: Measurement And Analysis, Rahul Pramod Sawant

Electrical Engineering Theses - Archive

Energy conservation is critical in Wireless Sensor Networks. Replacing or recharging batteries is not an option for sensors deployed in hostile environments. Generally communication electronics in the sensor utilizes most energy. This thesis studies the effect of changing the transmission power and baud rate on transmission distance. Using Shannon channel capacity formula and Log - Distance Path Loss Model, transmission distance is shown to be related to transmit power and baud rate. Extensive empirical readings are taken to confirm the above relation. The path loss exponent got as a result of data fitting is within the acceptable range for wireless …

Go to article

Electromagnetically Actuated Devices For Optical Coherence Tomography Applications, Hans P. Hu May 2007

Electromagnetically Actuated Devices For Optical Coherence Tomography Applications, Hans P. Hu

Electrical Engineering Dissertations - Archive

A fast optical scanning device has always been desired for numerous applications such as biomedical imaging, optical communications, and variety of sensing and actuating applications. This dissertation presents a new scanning device operated using external magnetic field with low cost, high function versatility, low field strength, and low power consumption. The design architecture of this device shows its potential for in vivo application with an advantage that addresses the concern of safety. Materials properties are examined using alternating gradient magnetometer(AGM) to verify its performance. Pressure and temperature invariant fabrication processes are implemented to make this device without complicated equipments. The …

Go to article

Discrete-Time Control Algorithms And Adaptive Intelligent Systems Designs, Asma Azmi Al-Tamimi May 2007

Discrete-Time Control Algorithms And Adaptive Intelligent Systems Designs, Asma Azmi Al-Tamimi

Electrical Engineering Dissertations - Archive

In this work, approximate dynamic programming (ADP) designs based on adaptive critic structures are developed to solve the discrete-time optimal control problems in which the state and action spaces are continuous. This work considers linear discrete-time systems as well as nonlinear discrete-time systems that are affine in the input. This research resulted in forward-in-time reinforcement learning algorithms that converge to the solution of the Generalized Algebraic Riccati Equation (GARE) for linear systems. For the nonlinear case, a forward-in-time reinforcement learning algorithm is presented that converges to the solution of the associated Hamilton-Jacobi Bellman equation (HJB). The results in the linear …

Go to article

Performance Analysis Of Dpsk Systems With Mimo Employing Egc Over Wireless Fading Channels, Iyad Al Falujah May 2007

Performance Analysis Of Dpsk Systems With Mimo Employing Egc Over Wireless Fading Channels, Iyad Al Falujah

Electrical Engineering Dissertations - Archive

The proliferation of digital wireless communication services has increased the congestion of the available radio spectrum. In addition to that, wireless communications are encountered by multipath channel fading. To alleviate the scarcity of the radio spectrum and multipath channel fading, attention in this dissertation is placed on differentially coherent phase shift keying (DPSK) systems with equal gain combining (EGC) diversity reception. DPSK systems are capable of achieving high spectral efficiency with adequate performance over wireless fading channels. Several wireless communication systems have adopted DPSK such as the time division multiple access (TDMA) version of the North American Digital Cellular (NADC) …

Go to article

H-Infinity Output Feedback Control: Application To Unmanned Aerial Vehicle, Jyotirmay Gadewadikar May 2007

H-Infinity Output Feedback Control: Application To Unmanned Aerial Vehicle, Jyotirmay Gadewadikar

Electrical Engineering Dissertations - Archive

This dissertation presents new necessary and sufficient conditions for static output-feedback control of linear time-invariant systems using the H-Infinity approach. Simplified conditions are derived which only require the solution of two coupled matrix design equations. It is shown that the static output-feedback H-Infinity solution does not generally yield a well-defined saddle point for the zero sum differential game; conditions are given under which it does. This work presents a simplified parameterization of all H-Infinity static state-feedback controllers in terms of a single algebraic Riccati equation and a free parameter matrix. As a special case, necessary and sufficient conditions for the …

Go to article

Ccbdi Readout Circuit For Ybacuo Micromachined Microbolometers, Sandeep Kumar May 2007

Ccbdi Readout Circuit For Ybacuo Micromachined Microbolometers, Sandeep Kumar

Electrical Engineering Dissertations - Archive

Semiconducting YBaCuO (Yttrium-Barium-Copper-Oxide) as a new uncooled microbolometer material is evaluated for CMOS compatibility. By not requiring cryogenic cooling, the self-supporting semiconducting YBaCuO micromachined microbolometers have found an attractive application for thermal detection with substantial reduction in system cost, size, weight and power consumption as compared to cooled photon detectors. The lower thermal conductance of the microbolometers to the substrate provides good sensitivity for infrared detection. The CCBDI (Constant Current Buffered Direct Injection) readout circuit is designed to work with a traditional frame rate of 30Hz and as a novel approach improves the performance of uncooled IR cameras by a …

Go to article

Design, Fabrication And Assembly Of 3-D Microstructures, Ping Zhang May 2007

Design, Fabrication And Assembly Of 3-D Microstructures, Ping Zhang

Electrical Engineering Dissertations - Archive

The primary goal of a micro-electro-mechanical system (MEMS) is to integrate electronics, sensors and actuators into a tiny system, which can be easily fabricated and packaged. Currently there is no standard process for manufacturing all the sub-components since a lot of them are made from different materials and fabrication technologies. Therefore, there is a great interest to develop a reliable manufacturing approach that allows for the integration of multiple micro devices on a single chip. This work describes two approaches to achieve this heterogeneous integration: (1) hybrid material integration by introducing new materials into a well-known self-assembly platform (PolyMUMPs) to …

Go to article

Thermal Effects On Analog Integrated Circuit Design, Md Mahbub Hossain May 2007

Thermal Effects On Analog Integrated Circuit Design, Md Mahbub Hossain

Electrical Engineering Dissertations - Archive

Analog Integrated Circuit design (IC) is a big challenge in this modern age. Thermal effect has a substantial role in analog ICs performance. Thermal effects on analog IC design have been investigated in this dissertation project. National Semiconductor Corporation's Vertical Bipolar Inter-Company (VBIC) model of dielectrically isolated bipolar junction transistors (DIBJT) with VIP10 and VIP11 processes have been used for the research. These devices are used for the high speed IC design. Self-heat generated inside these devices is confined within the device and degrades the device performance. In addition, the thermal characteristic of a device surrounded by the multiple adjacent …

Go to article

First Prev Next Last