Electrical and Computer Engineering Commons^™

Simplifying Embedded System Development Through Whole-Program Compilers, William Patrick Mccartney

ETD Archive

As embedded systems embrace ever more complicated microcontrollers, they present both new capability and new complexity. To simplify their development, some lessons of computer application development will translate with additional work. This thesis offers one such translation. It shows how whole-program compilers - those that broadly analyze a program's entire source code - can achieve performance gains and remove faults in embedded system applications. In so doing, this yields a novel stackless threading system named UnStacked C. UnStacked C enables cooperative multithreading without the risk of stack overflows in embedded system applications. We also propose a novel preemption system called …

Free Space Optical Communications With High Intensity Laser Power Beaming, Daniel Edward Raible

ETD Archive

This research demonstrates the feasibility of utilizing high intensity laser power beaming (HILPB) systems as a conduit for robust free-space optical communications over large distances and in challenging atmospheric conditions. The uniqueness of vertical multi-junction (VMJ) photovoltaic cells used in HILPB systems in their ability to receive and to convert at high efficiency, very high intensity laser light of over 200 W/cm2, presents a unique opportunity for the development of the robust free space optical communication system by modulating information signals onto the transmitted high intensity photonic energy. Experiments were conducted to investigate and validate several optical communications concepts. A …

Partial-Data Interpolation During Arcing Of An X-Ray Tube In A Computed Tomography Scanner, Jaisingh Rajwade

ETD Archive

X-ray tubes are used in computed tomography (CT) scanners as the energy source for generation of images. These tubes occasionally tend to arc, an undesired phenomenon where high current surges through the tube. During the time that the x-ray tube recovers to full voltage after an arc, image data is being collected. Normally this data, acquired at less than full voltage, is discarded and interpolation is performed over the arc duration. However, this is not ideal and some residual imperfections in images, called artifacts, still remain. Proposed here is an algorithm that corrects for improper tube voltage, allowing previously discarded …

Dynamic Harmonic Domain Modeling Of Flexible Alternating Current Transmission System Controllers, Bharat Gnvsr Vyakaranam

ETD Archive

Flexible alternating current transmission system (FACTS) and multi-line FACTS controllers play an important role in electrical power transmission systems by improving power quality and increasing power transmission capacity. These controllers are nonlinear and highly complex when compared to mechanical switches. Consequently, during transient conditions, it is very difficult to use conventional time and frequency domain techniques alone to determine the precise dynamic behavior of the harmonics introduced into the system by these controllers. In particular, the time-varying nature of the harmonic components is not captured by these techniques. The contribution of this work to the state of power systems analysis …

Intelligent Controls For A Semi-Active Hydraulic Prosthetic Knee, Timothy Allen Wilmot

ETD Archive

We discuss open loop control development and simulation results for a semi-active above-knee prosthesis. The control signal consists of two hydraulic valve settings. These valves control a rotary actuator that provides torque to the prosthetic knee. We develop open loop control using biogeography-based optimization (BBO), which is a recently developed evolutionary algorithm, and gradient descent. We use gradient descent to show that the control generated by BBO is locally optimal. This research contributes to the field of evolutionary algorithms by demonstrating that BBO is successful at finding optimal solutions to complex, real-world, nonlinear, time varying control problems. The research contributes …

The Relational Database: A New Static Analysis Tool?, Adam M. Dutko

ETD Archive

Code comprehension is pivotal to reducing errors in software. Reading source code improves code comprehension and enables effective fixes but as a code base grows meta-data become increasingly important. Static Analysis techniques provide an avenue for software developers to learn more about their code through meta-data while also helping them safely detect potential errors in their source. Unfortunately, many Static Analysis tools have a steep learning curve and are limited in scope. This thesis seeks to make Static Analysis accessible and extensible by asking what ubiquitous tools like SQL and relational databases can offer and what they cannot. We begin …

Efficient Time Of Arrival Calculation For Acoustic Source Localization Using Wireless Sensor Networks, Prashanth G. Reddy

ETD Archive

Acoustic source localization is a very useful tool in surveillance and tracking applications. Potential exists for ubiquitous presence of acoustic source localization systems. However, due to several significant challenges they are currently limited in their applications. Wireless Sensor Networks (WSN) offer a feasible solution that can allow for large, ever present acoustic localization systems. Some fundamental challenges remain. This thesis presents some ideas for helping solve the challenging problems faced by networked acoustic localization systems. We make use of a low-power WSN designed specifically for distributed acoustic source localization. Our ideas are based on three important observations. First, sounds emanating …

Implementing A Piezoelectric Transformer For A Ferroelectric Phase Shifter Circuit, Anthony M. Roberts

ETD Archive

No abstract provided.

Implementation Of An Advanced Controller On A Torsional Mechanism, Chintan Trivedi

ETD Archive

The hardware implementation of an active disturbance rejection controller (ADRC) is presented in the thesis for a mechanical torsional plant. ADRC is a novel disturbance rejection control technique that is not completely dependent on mathematical models of physical systems. In ADRC framework external disturbances, system uncertainties, and internal dynamics of the system are estimated as a generalized disturbance by an extended state observer and the generalized disturbance is effectively canceled by a PD controller. A torsional plant represents a class of rotational systems. Its control challenges are the vibrations caused by mass imbalance, centrifugal imbalance, and the imbalance caused by …

Multi-Antenna Non-Line-Of-Sight Identification Techniques For Target Localization In Mobile Ad-Hoc Networks, Wenjie Xu

Dissertations, Master's Theses and Master's Reports - Open

Target localization has a wide range of military and civilian applications in wireless mobile networks. Examples include battle-field surveillance, emergency 911 (E911), traffc alert, habitat monitoring, resource allocation, routing, and disaster mitigation. Basic localization techniques include time-of-arrival (TOA), direction-of-arrival (DOA) and received-signal strength (RSS) estimation. Techniques that are proposed based on TOA and DOA are very sensitive to the availability of Line-of-sight (LOS) which is the direct path between the transmitter and the receiver. If LOS is not available, TOA and DOA estimation errors create a large localization error. In order to reduce NLOS localization error, NLOS identifcation, mitigation, and …

A Midsummer Night’S Dream (With Flying Robots), Robin Murphy, Dylan Shell, Amy Guerin, Brittany Duncan, Benjamin Fine, Kevin Pratt, Takis Zourntos

School of Computing: Faculty Publications

Seven flying robot “fairies” joined human actors in the Texas A&M production of William Shakespeare’s A Midsummer Night’s Dream. The production was a collaboration between the departments of Computer Science and Engineering, Electrical and Computer Engineering, and Theater Arts. The collaboration was motivated by two assertions. First, that the performing arts have principles for creating believable agents that will transfer to robots. Second, the theater is a natural testbed for evaluating the response of untrained human groups (both actors and the audience) to robots interacting with humans in shared spaces, i.e., were believable agents created? The production used two types …

Performance Analysis Of Mimo-Sess With Alamouti Scheme Over Rayleigh Fading Channels, Shichuan Ma, Lim Nguyen, Yaoqing Lamar Yang, Won Mee Jang

Department of Electrical and Computer Engineering: Faculty Publications

Self-encoded spread spectrum (SESS) is a novel modulation technique that acquires its spreading sequence from the random input data stream rather than through the use of the traditional pseudo-noise code generator. It has been incorporated with multiple-input multiple-output (MIMO) systems as a means to combat fading in wireless channels. In this paper, we present the analytical study of the bit-error rate (BER) performance of MIMO-SESS systems under Rayleigh fading. The BER expressions are derived in closed form, and the veracity of the analysis is confirmed by numerical calculations that demonstrate excellent agreement with simulation results. The performance analysis shows that …

All-Dielectric Invisibility Cloaks Made Of Batio3-Loaded Polyurethane Foam, Di Bao, Khalid Z. Rajab, Yang Hao, Efthymios Kallos, Wenxuan Tang, Christos Argyropoulos, Yongzhe Piao, Shoufeng Yang

Department of Electrical and Computer Engineering: Faculty Publications

Transformation optics has led the way in the development of electromagnetic invisibility cloaks from science fiction to engineering practice. Invisibility cloaks have been demonstrated over a wide range of the electromagnetic spectrum, and with a variety of different fabrication techniques. However, all previous schemes have relied on the use of metamaterials consisting of arrays of sub-wavelength inclusions. We report on the first cloaking structure made of a high-k dielectric-loaded foam mixture. A polyurethane foam mixed with different ratios of barium titanate is used to produce the required range of permittivities, and the invisibility cloak is demonstrated to work for all …

Energy Efficiency And Goodput Analysis In Two-Way Wireless Relay Networks, Qing Chen, M. Cenk Gursoy

Department of Electrical and Computer Engineering: Faculty Publications

In this paper, we study two-way relay networks (TWRNs) in which two source nodes exchange their information via a relay node indirectly in Rayleigh fading channels. Both Amplify-and-Forward (AF) and Decode-and-Forward (DF) techniques have been analyzed in the TWRN employing a Markov chain model through which the network operation is described and investigated in depth. Automatic Repeat-reQuest (ARQ) retransmission has been applied to guarantee the successful packet delivery. The bit energy consumption and goodput expressions have been derived as functions of transmission rate in a given AF or DF TWRN. Numerical results are used to identify the optimal transmission rates …

Ann-Based Adaptive Pi Control For Wind Turbine With Doubly Fed Induction Generator, Baohua Dong, Sohrab Asgarpoor, Wei Qiao

Department of Electrical and Computer Engineering: Faculty Publications

This paper focuses on developing a novel algorithm which dynamically optimizes the controllers of doubly fed induction generator (DFIG) driven by a wind turbine (WT) to increase DFIG transient performance in all wind speed conditions. Particle swarm optimization (PSO) is proposed to optimize parameters of PI controllers of DFIG’s rotor side/grid side converters (RSC/GSC) at different wind speeds in order to maximize the damping ratios of the system eigenvalues in small signal stability analysis. Based on the optimal values and the wind speed data set, an artificial neural network (ANN) is designed, trained, and it has the ability to quickly …

Throughput Analysis Of Buffer-Constrained Wireless Systems In The Finite Blocklength Regime, M. Cenk Gursoy

Department of Electrical and Computer Engineering: Faculty Publications

In this paper, wireless systems operating under queueing constraints in the form of limitations on the buffer violation probabilities are considered. The throughput of wireless systems operating under such constraints is captured by the effective capacity formulation. It is assumed that finite blocklength codes are employed for transmission. Under this assumption, a recent result on the channel coding rate in the finite blocklength regime is incorporated into the analysis and the throughput achieved with such codes in the presence of queueing constraints is identified. Interactions between the effective rate, queueing constraints, error probabilities, and blocklength values are investigated. In particular, …

Self-Reconfigurable Multicell Batteries, Taesic Kim, Wei Qiao, Liyan Qu

Department of Electrical and Computer Engineering: Faculty Publications

The traditional multicell battery design usually employs a fixed configuration to connect multiple cells in series and parallel during operation in order to achieve the required voltage and current. However, this fixed configuration results in low reliability, low fault tolerance, and non-optimal energy conversion efficiency. This paper proposes a novel self reconfigurable, multicell battery design. The proposed multicell battery can automatically configure itself according to the dynamic load/storage demand and the condition of each cell. The proposed battery can self-heal from failure or abnormal operation of single or multiple cells, self-balance from cell state variations, and self-optimize to achieve the …

Raiphy: Phylogenetic Classification Of Metagenomics Samples Using Iterative Refinement Of Relative Abundance Index Profiles, Ozkan U. Nalbantoglu, Samuel F. Way, Steven H. Hinrichs, Khalid Sayood

Department of Electrical and Computer Engineering: Faculty Publications

Background: Computational analysis of metagenomes requires the taxonomical assignment of the genome contigs assembled from DNA reads of environmental samples. Because of the diverse nature of microbiomes, the length of the assemblies obtained can vary between a few hundred bp to a few hundred Kbp. Current taxonomic classification algorithms provide accurate classification for long contigs or for short fragments from organisms that have close relatives with annotated genomes. These are significant limitations for metagenome analysis because of the complexity of microbiomes and the paucity of existing annotated genomes.

Results: We propose a robust taxonomic classification method, RAIphy, that …

Energy Efficiency In The Low-Snr Regime Under Queueing Constraints And Channel Uncertainty, Deli Qiao, M. Cenk Gursoy, Senem Velipasalar

Department of Electrical and Computer Engineering: Faculty Publications

Energy efficiency of fixed-rate transmissions is studied in the presence of queueing constraints and channel uncertainty. It is assumed that neither the transmitter nor the receiver has channel side information prior to transmission. The channel coefficients are estimated at the receiver via minimum mean-square-error (MMSE) estimation with the aid of training symbols. It is further assumed that the system operates under statistical queueing constraints in the form of limitations on buffer violation probabilities. The optimal fraction of power allocated to training is identified. Spectral efficiency–bit energy tradeoff is analyzed in the low-power and wideband regimes by employing the effective capacity …

A Directional Gamma Ray Detector Using A Single Chip Computational Sensor, Nathan R. Schemm, Sina Balkir, Michael W. Hoffman, Mark Bauer

Department of Electrical and Computer Engineering: Faculty Publications

This paper presents the design and test results of a computational radiation sensor system based on a single chip solution that can determine the direction of gamma rays emitted from a radiation source. The overall system is formed by merging a sensor section with a compact and low power computational radiation sensor section. The sensor section houses three NaI gamma ray detectors arranged in a spatial configuration that allows for direction finding. The computational sensor is based on a single chip solution developed by authors that houses multiple low power sensor front ends, event driven analog-to-digital converters, and a dedicated …