Engineering Commons^™

Characterization Of Gan Thin Films Grown By Rf Magnetron Sputtering For Fabrication Of An Algan/Gan Hemt Biosensor, Rocio Yolanda Garza

Theses and Dissertations - UTB/UTPA

Radio-Frequency (RF) Magnetron Sputtering has been used to grow GaN thin films for future fabrication of an AlGaN/GaN HEMT biosensor. A GaN target was sputtered at various parameters on silicon and sapphire substrates, at room temperature and at elevated temperature using substrate heating and post deposition annealing treatment. The research conducted investigates the effects of sputtering gas (Argon or Nitrogen gas), RF power (40W or 50W), and pressure (4mT – 30mT) on the structural properties of the thin films. Imaging tools such as the Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDS), X-ray Diffractometer (XRD), and …

Seeds Of Solutions™: An Economical & Efficient Approach Towards Power Engineering Education, Eli Alvarez

Theses and Dissertations - UTB/UTPA

Power demands are set to increase over the next twenty years; however, research shows that there may be a shortage of power engineers due to an appreciable percentage of the current power engineer workforce retiring, insufficient enrollment in power engineering programs and a lack of emphasis in power engineering at the university level. This thesis provides supporting research for future power demands, workforce and faculty shortages. Using temporary research in modern learning / teaching styles, student / teacher perceptions, educational trends and regional course offerings, this thesis describes a learning approach towards power engineering education. Designed specifically for universities with …

A 129nw Neural Amplifier And Gm-C Filter For Eeg Using Gm/Id Methodology, Samuel A. Gallegos

Theses and Dissertations - UTB/UTPA

This Thesis presents a low-power analog front-end amplifier and Gm-C filter for biomedical sensing applications, specifically for Electroencephalogram (EEG) use. The proposed neural amplifier uses a supply voltage of 1.8V, it has a mid-band gain of 40.75dB, and consumes a total current of 71.82nA, for a total dissipated power of 129.276nW. Also presented is the design of a 3rd order Butterworth Low Pass Gm-C Filter which makes use of 14.7nS transconductors; the proposed filter has a pass band suitable for EEG recording use (1-100Hz). The amplifier and filter utilize current sources without bias resistances which provide 56nA and (1.154nA x …

Applications Of Magnetostrictive Materials In The Real-Time Monitoring Of Vehicle Suspension Components, Raul Estrada

Theses and Dissertations - UTB/UTPA

The purpose of this project is to explore applications of magnetostrictive materials for real-time monitoring of railroad suspension components, in particular bearings. Monitoring of such components typically requires the tracking of temperature vibration and load. In addition, real-time, long-term monitoring can be greatly facilitated through the use of wireless, self-powered sensors. Magnetostrictive materials, such as Terfenol-D, have the potential to address both requirements. Currently, piezoelectrics are used for many load and energy harvesting applications; however, they are fragile and are difficult to use for static load measurements. Magnetostrictive metals are tougher, and their property of variable permeability when stressed can …

Dynamic Wireless Power Transfer System For The Unmanned Aerial Vehicles, Tae Sup Lee

Open Access Theses

UAVs have limitless applications to help our daily lives for the autonomous operations. UAVs have a limited power capacity due to weight constraints and are therefore not able to travel long distances. Ground stations for recharging UAVs throughout different points can increase the flight time of the UAVs with the current UAV battery capacity. This study investigates how the wireless charging system for the ground station can be made more robust when there are misalignments. The wireless charging system is monitored by an Arduino, micro controller, to assess the current condition of charging. The Arduino is able to change the …

Realization And Evaluation Of A 3-Degrees-Of-Freedom Mouse Model, Udayan Umapathi

Open Access Theses

Kinesiology research has shown that translation and rotation are inseparable actions in the real world. Motivated by this fact, this thesis explores a model for the computer mouse, the new addition being rotational input about vertical axis of a mouse. We realize our model through Mushaca, a 3-degrees-of-freedom mouse (3DOF mouse) that can sense rotation, in addition to sensing XY planar translation. The thesis presents two realizations of Mushaca - namely a MEMS version that uses accelerometer and gyroscope, and an optical sensor version that uses two optical sensors. Through a controlled user study we try to find out if …

Quartz-Mems: Wet Chemical Etching Assisted By Electromagnetic Energy Sources For The Development Of Quartz Crystal To Be Used For Microelectromechanical Systems, William J. Clower

Doctoral Dissertations

Quartz crystal resonators have been the most commonly used timing devices to date. Today's timing market requires devices to be as small as possible and consume smaller amounts of energy. Because of the market demand, many startup companies have formed to develop silicon resonators as timing devices. Silicon resonators have poor noise and temperature performance (due to its linear temperature versus frequency coefficient). At the moment the only advantage that silicon resonators have over quartz crystal resonators is a small form factor. The photolithography processing method currently being used in industry is a very tedious task, requiring multiple etching steps …

Cluster Computer Simulation Of Buffer Sharing Schemes Under Bursty Traffic Load, Javier Castillo

Theses and Dissertations - UTB/UTPA

In this thesis it is first analyzed the effect that different Average Burst Length, buffer size or number of ports have on the performance in terms of packet loss ratio on shared memory network switches using Complete Sharing as baseline for the memory allocation scheme. Three different shared memory allocation schemes - Sharing with a Minimum Allocation (SMA), Sharing with Maximum Queue lengths (SMXQ), and Dynamic Threshold (DT) - are then analyzed under varied traffic conditions in order to determine the best configuration for each tested scenario. Having determined the best configuration for each individual scheme under all the tested …

Particle Swarm Optimization Using Multiple Neighborhood Connectivity And Winner Take All Activation Applied To Biophysical Models Of Inferior Colliculus Neurons, Brandon S. Coventry

Open Access Theses

Age-related hearing loss is a prevalent neurological disorder, affecting as many as 63% of adults over the age of 70. The inability to hear and understand speech is a cause of much distress in aged individuals and is becoming a major public health concern as age-related hearing loss has also been correlated with other neurological disorders such as Alzheimer's dementia. The Inferior Colliculus (IC) is a major integrative auditory center, receiving excitatory and inhibitory inputs from several brainstem nuclei. This complex balance of excitation and inhibition gives rise to complex neural responses, which are measured in terms of firing rate …

Improved Random Demodulator For Compressed Sensing Applications, Sathya Narayanan Hariharan

Open Access Theses

The advances in the field of signal processing have led to the continuous increase in the bandwidth of signals. Sampling these signals becomes harder and harder due to the increased bandwidth. This brings in need for a complex high rate ADCs to meet the Nyquist rate which is the minimum rate to avoid aliasing. For a given increase in bandwidth, there has to be a corresponding increase in the sampling rate of ADC. This might not be possible in the near future at the current rate of increase in bandwidth. Hence, there is a need to replace the current Nyquist …

Optical Position Sensing In Free Space Optical Communication, Muhammad Salman Bashir

Open Access Theses

In this thesis the performance of three estimators, (center of gravity, template matching and maximum likelihood (MLE)) to estimate the center of the beam on a photoemissive receiver array in a Free Space Optics (FSO) system, is compared in terms of mean square error. Simulations have been conducted in Matlab by generating a two dimensional nonhomogeneous Poisson process, and, mean square error is computed for three estimators. The cases of continuous and discrete arrays are also considered for various levels of signal-to-noise (SNR) ratio. Simulations have shown that the MLE gives the least mean squared error and especially performs significantly …

A Lightweight N-Cover Algorithm For Diagnostic Fail Data Minimization, Shraddha Ghanshyam Bodhe

Open Access Theses

The increasing design complexity of modern ICs has made it extremely difficult and expensive to test them comprehensively. As the transistor count and density of circuits increase, a large volume of fail data is collected by the tester for a single failing IC. The diagnosis procedure analyzes this fail data to give valuable information about the possible defects that may have caused the circuit to fail. However, without any feedback from the diagnosis procedure, the tester may often collect fail data which is potentially not useful for identifying the defects in the failing circuit. This not only consumes tester memory …

Integration And Implementation Of High-Voltage Energy Storage Sub-System For A Parallel-Through-The-Road Plug-In Hybrid Electric Vehicle, Bilwa A. Jadhav

Open Access Theses

With research showing an alarming rate of increase in global warming and thus causing dangerous instabilities in the weather, a strong push has been initiated to reduce greenhouse gas emissions. Transportation being one of the top offenders in greenhouse gas emissions, has led the drive for improving the efficiency of the modern automobile. One of the current strategies for reducing the emissions produced by the transportation sector is hybrid vehicles powered from both a fuel such as gasoline, diesel, or hydrogen; and electricity. This merger has proven to be effective at decreasing harmful emissions including, carbon dioxide (CO 2 ) …

An Analytical And Experimental Biosensor For Human Mig Using Algan/Gan Based Hemt Devices, Hector Trevino Ii

Theses and Dissertations - UTB/UTPA

An amperometric biosensor using AlGaN/GaN based HEMT devices is constructed experimentally and validated through analytical and numerical techniques for detection of a key protein in allograft rejection (Human MIG/CXCL9). The prototype developed provides a reliable sensing platform that will allow label-free and marker-free detection. By exploiting characteristics unique to AlGaN/GaN based HEMT devices, a floating gate configuration is employed to allow reliable sensing without the need for any reference electrode. Self-assembled monolayers (SAM) are formed at the gate surface by using a crosslinker (DSP) to allow for appropriate immobilization of target antibodies. A theoretical analytical and numerical model is developed …

Distributed Formation Tracking Control Of Multiple Car-Like Robots, Chunyu Chen

Theses and Dissertations - UTB/UTPA

In this thesis, distributed formation tracking control of multiple car-like robots is studied. Each vehicle can communicate and send or receive states information to or from a portion of other vehicles. The communication topology is characterized by a graph. Each vehicle is considered as a vertex in the graph and each communication link is considered as an edge in the graph. The unicycles are modeled firstly by both kinematic systems. Distributed controllers for vehicle kinematics are designed with the aid of graph theory. Two control algorithms are designed based on the chained-form system and its transformation respectively. Both algorithms achieve …

Developing A Hardware Platform For A Low-Power, Low-Cost, Size-Constrained Biomechanical Telemetry System, Aditya Balasubramanian

Open Access Theses

As sport-related traumatic brain injuries face increasing attention from the media and the general public, the need to be able to detect brain injury quickly, inexpensively and accurately is more important than ever. Commercially-available event-based systems exist that claim to achieve this goal; however, they collect little to no continuous-time data and primarily indicate when a pre-determined acceleration threshold has been exceeded under the unvalidated assumption that a potentially concussive blow has occurred. Recent findings by the Purdue Neurotrauma Group (PNG) have indicated that repeated exposure to both concussive and subconcussive blows can result in cumulative trauma disorder. To track …

Integrated Dc-Dc Boost Converters Using Cmos Silicon On Sapphire Technology, Imaduddin Mohammad

Open Access Theses

With the recent advancements in semiconductor manufacturing towards smaller, faster and more efficient microelectronic systems, the problems of increasing leakage current and reduced breakdown voltage in bulk-CMOS transistors have become substantial in the sub-100-nanometer era. The Peregrine UltraCMOS Silicon-on-Sapphire (SOS) technology that uses highly-insulating sapphire substrate as insulator was introduced to meet the continually growing need for higher performance RF products. The electrically isolated circuit elements in the UltraCMOS technology lead to increased switching speeds and lower power consumption due to reduced junction and parasitic capacitances. Furthermore, the growing need for high-speed switching applications such as boosting a lower voltage …

Properties Of Ambiguity Functions, John Mulcahy-Stanislawczyk

Open Access Theses

The use of ambiguity functions in radar signal design and analysis is very common. Understanding the various properties and meanings of ambiguity functions allow a signal designer to understand the time delay and doppler shift properties of a given signal. Through the years, several different versions of the ambiguity function have been used.

Each of these functions essentially have the same physical meaning; however, the use of different functions makes it difficult to be sure that certain properties hold for different formulations. This work proves several parallel properties of two versions of the asymmetric ambiguity function, the symmetric ambiguity function, …

Computer Modeling And Simulation Of Implantable Medical Device Heating Due To Mri Gradient Coil Fields, Bryan David Stem

Open Access Theses

For patients with implantable medical devices, the ability to safely undergo MRI scanning is critical to ensuring the highest standard of care. The gradient coils of an MRI generate kilohertz frequency, time varying magnetic fields. These magnetic fields induce a voltage on the external case of metallic, implantable medical devices through electromagnetic induction. Since the magnetic field generated by a gradient coil is time varying, the induced voltage results in the flow of eddy currents which can cause heating effects. These heating effects have been successfully modeled using ANSYS Maxwell and ANSYS Mechanical software packages.

The multi-physics simulation and solution …

Comparison Of A Sierpinski Gasket Monopole Antenna To Bow-Tie Antennas Based Off The Fractal Iterative Shapes, Kyle Nathan Murg

Open Access Theses

Antennas are an integral part of mobile devices. Recently, the demand for smaller phones has increased requiring smaller components within the device. This leads to problems with performance and limitations of RF systems within mobile devices including antennas which have been affected by the size thus affected frequency output. In this thesis, fractal theory will be utilized to compare the performance of the Sierpinski Gasket Monopole antenna to single band antennas to see if this is a viable substitute in mobile applications. By utilizing simulations and physical antennas, the performance will be observed at each frequency band and compared.