Engineering Commons^™

Regulation Issues And Prediction Of Natural Estrogen Loads For Wastewater Treatment Plants, Michelle E. Jarvie

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

No abstract provided.

Design And Manufacturing Of Functionally Graded Materials With Polymer Chain And Nano-Reinforcement Orientation For Compressive Applications, Sanjay Varma Kalidindi

Theses and Dissertations - UTB/UTPA

Functionally Graded Materials for compressive applications were designed and manufactured by tailoring the properties of Pure Polyethylene (PE) and Vapor Grown Carbon Nanofiber (VGCNF) Reinforced PE Composites. Properties of NRPC have been extensively studied. Properties are dependent on parameters such as the reinforcement/matrix interaction; reinforcement volume fraction, orientation, dispersion, and packing, and the final matrix microstructure. However, there is limited literature on their properties under compression loading. Compression strength studies for high density PE reinforced with VGCNF for different fiber volume fraction (0%, 5%, 10% and 15%) were carried out. The role of interface and alignment was studied. Samples were …

Electrorheology Of Fullerene Suspensions, Maricela Lizcano

Theses and Dissertations - UTB/UTPA

Electrorheological fluids are suspension materials whose rheological behavior changes with an applied voltage. In particular, the material changes from a fluid to a solid behavior with an applied voltage and reverses to its original state when the voltage is removed. This function classifies ER fluids as smart materials. ER fluids may be developed and used as mechanical devices with no mechanical parts such as pumps, actuators, and dampers. Until recently, research was concentrated with micro-particle suspension fluids. This research project investigates the electrorheology of carbon nano-particle suspension.

Comparison Of Sliding Mode And State-Feedback Control Applied To A Partially Treated Actively Constrained Layer Damped (Acld) Beam, Jose J. Rodriguez

Theses and Dissertations - UTB/UTPA

In this research, a sliding mode control (SMC) was utilized in the control of a partially treated, actively constrained layer damped (ACLD), Timoshenko beam model. The resulting vibration control was compared to the vibration control achieved by a state-feedback linear quadratic regulator (LQR) for several loading conditions. An observer was designed and model order reduction (MOR) was performed to achieve a simplified, efficient, and more controllable finite element system model. As a result of model simplification, modeling errors in the form of unstructured uncertainties were introduced into the system. It was determined that the SMC and LQR achieved similar vibration …

A Stochastic Production Cost Model For Remanufacturing Systems, Gaurang S. Patel

Theses and Dissertations - UTB/UTPA

Growing environmental concern throughout this decade coupled with enforced legislation, customer expectations and economic incentives have forced increasing number of manufacturers to take back their products from end user. Managing this reverse flow of products is called reverse logistics. The stochastic nature of returned products complicates the production planning for remanufacturing systems in reverse logistics. In this thesis a stochastic production cost model, considering various costs associated under different situations for remanufacturing systems of returned products is developed. A search algorithm method is recommended to determine optimal production run size, production rate and space for remanufacturing systems in reverse logistics. …

The Optimization Of Amplifiers For Uwb Applications, Kyoung D. Kim

Theses and Dissertations - UTB/UTPA

Optimizations of 0.18 μm and 0.5 μm MOSFET amplifiers without using inductors for UWB applications are presented. A 3 dB bandwidth from 3.1 GHz to 9.9 GHz with minimum 9.6 dB of transducer gain at 10.6 GHz and approximate 92.8 mWatts of total power consumption are achieved. The source and load impedances were 50 ohms. Also, the number of capacitors and resistors has been minimized. To predict characteristics more precisely, the pad capacitance is added to the output port. In addition, a different feedback topology is presented which gives a lower Noise Figure with maximum 7.73 dB at 10.6 GHz …

Moving And Stationary Target Acquisition Radar Image Enhancement Through Polynomial Windows, Rajarajeswari Devarajulu

Theses and Dissertations - UTB/UTPA

The Fourier transform involved in synthetic aperture radar (SAR) imaging causes undesired sidelobes which obscure weak backscatters and affect the image clarity. These sidelobes can be suppressed without deteriorating the image resolution by smoothing functions known as windowing or apodization. Recently, the theory of orthogonal polynomials has gained considerable attention in signal processing applications. The window functions that are derived from the orthogonal polynomials have interesting sidelobe roll-off properties for better sidelobe apodization, hence it can be used for radar image enhancement. In this work, a new window is constructed from Jacobi orthogonal polynomials and its performance in SAR imaging …

Composite Mechanical Property Enhancement Through The Use Of Y-End Shaped Short Fibers, Jin Tan

Theses and Dissertations - UTB/UTPA

This study uses Finite Element Analysis (FEA) to predict the mechanical property enhancement of the composites reinforced by end-shaped short fibers with different aspect ratios and volume fractions at microscale. Fibers used include conventional straight short fibers (CSSF), dumbbell-end shaped short fibers (DSSF), bone-end shaped short fibers (BSSF) and Y-end shaped short fibers (YSSF) with various lengths and angles. The critical distances between neighboring fiber ends for FEA modeling were theoretically deduced and numerically verified. This study has never been done before and the results fill a gap to this field.

In conclusion, planar-end Y-shaped short fiber reinforced composites showed …

Application Of Polyelectrolyte Layer-By-Layer Nano-Assembly For Surface Modification, Encapsulation And Controlled Release, Nikhil Anil Pargaonkar

Doctoral Dissertations

In this study, we applied the traditional Electrostatic layer-by-layer (ELBL) assembly procedure to fabricate nanothin films over flat surfaces, and modify particle surfaces to influence the drug particle size, and drug release. The ELBL assembly has previously been applied to fabricate multilayer nano-scale thin films, but its ability to instantaneously influencing particle size is unique. Other unique observations such as influence on drug release as a result of polymer complexation, and thermal changes occurring during layer fabrication are recorded.

The ELBL self-assembly process was applied to produce dexamethasone particles layered with various polyelectrolyte layer combinations. These combinations were further applied …

Design And Performance Evaluation Of Switching Architectures For High-Speed Internet, Alvaro Munoz

Theses and Dissertations - UTB/UTPA

The motivation for this thesis is the desire to build faster and scalable routers that efficiently handle the exponential traffic growth in the Internet. The Internet forwards information through a mesh of routers and switches, which has to keep up with the increasing demands of traffic. Shared-memory based switches are known to provide the best throughput-delay performance for a given memory size. In this thesis performance of commonly used memory-sharing schemes for the shared memory switches are evaluated under balanced and unbalanced bursty traffic. The scalability of shared-memory switches has been a research issue for quite sometime. One approach is …

Extension Of Stereolithography Mold Life Using Gas-Assisted Injection Molding, Dilip Bose Ramalingam Nagarajan

Theses and Dissertations - UTB/UTPA

Stereolithography (SL) molds show great promise for injection molding of limited number of parts, greatly reducing the time to product and production cost. However, they present challenges to designers because of their strength, thermal characteristics and shorter lifetimes compared to metal molds. Gas-assisted injection molding (GAIM) has been used to alleviate the problems of distortion and thermal damage. The use of GAIM makes it possible to produce a large number of parts compared to conventional injection molding in epoxy molds with higher quality. In this research solid models of the mold with different part geometry were created using CAD and …

The Use Of Confidence Intervals For The Control Limits Of X¯ And S Control Charts, Daniel A. Lopez

Theses and Dissertations - UTB/UTPA

This research focuses on the variation observed on the control limits of X¯ and S control charts, due to the sampling schemes. In previous studies it has been shown that the estimated control limits derived by a small number of subgroups does not help in setting up reliable control limits. It has also been shown that estimating control limits from a large number of subgroups is not a feasible option. In this research quantile tables will be derived by sampling from the standard normal distribution and used to explain the effects of sampling on the control limits. The tables will …

Biosensing With Microcantilever-Based Sensors, Xiaodong Yan

Doctoral Dissertations

Microcantilevers provide an ideal platform for biosensors. The micron-sized transducer brings several advantages, such as high sensitivity, small sample quantity for analysis, portability, implantable sensor devices, and the ability to be mass produced and integrated into standard microelectronic processing technologies like complementary metal oxide seminconductors (CMOS).

The objective of this research is to investigate and develop modification methods of microcanitlevers for biosensing applications.

Two microcantilever modification methods were investigated. They are self-assembly monolayer method and layer-by-layer method. A fundamental procedure for modification of microcantilevers using the layer-by-layer approach was developed for the first time in this research. These modification methods …

Countermeasures Against Scour At Bridge Abutments, Hua Li

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

Scour at bridge abutments can cause damage or failure of bridges and result in excessive repairs, loss of accessibility, or even death. To mitigate abutment scour, both clear-water and live-bed laboratory experiments in a compound channel were performed using parallel walls and spur dikes as countermeasures, respectively. In addition, collars were tested under clear-water conditions only. It was found that both parallel walls and spur dikes can efficiently protect the abutment from scour provided that they are properly designed. Design guidelines were discussed for both countermeasures. Preliminary clear-water tests of collars as countermeasures against scour showed some promising results although …

Rf Cmos Receiver Front-End Using A Reflex Amplifier, Radovan Kuzet

Theses and Dissertations - UTB/UTPA

A concept for an RF-CMOS receiver with reflex topology is developed and tested, using OrCad as the primary design and simulation tool. The main idea of the reflex topology is to reuse a Low Noise Amplifier (LNA) stage in the circuit and thus eliminate one high power consumption stage. A Gilbert cell is used for down conversion, with the benefit of low noise and low power while maintaining gain. A set of passive diplexers allows reuse of the LNA at the RF and IF. The complete circuit was simulated using 0.18 micron and 0.5 micron AMI technology. Parameters for the …

The Development Of Web-Based Aerobic And Anaerobic And Muscle Static Work Capacity Modules Using Legacy Cycle Approach, Anant Ravindra Deshpande

Theses and Dissertations - UTB/UTPA

The Legacy cycle is an instructional model that emphasizes inquiry. Learners are faced with progressively complex challenges. For each challenge, learners generate initial thoughts on how they might react to the challenges. In this thesis, a web based instructional method that evaluates interactivity and motivation is presented. The system presented in the thesis helps student to integrate the use of legacy cycle approach in the regular study of aerobic and anaerobic and muscle static work capacity modules. The thesis also focuses on developing modules which contain challenges encompassing various sections, which helps student as an asynchronous learning tool, intended for …

Dynamic Mechanical And Thermal Analysis Of Aligned Vapor Grown Carbon Nanofibers Reinforced Polyethylene, Jose Jaime Taha-Tijerina

Theses and Dissertations - UTB/UTPA

Dynamic-mechanical and thermal characterization of aligned vapor grown carbon-nanofibers (VGCNFs)-reinforced high-density polyethylene (HDPE) has been performed. VGCNFs with diameters ranging from 50–200nm were used. Nanofibers were purified to remove amorphous carbon and metal catalyst, resulting in deagglomeration, and creating an open network that allowed polymer infiltration during mixing. High-shear mixing was used to disperse and distribute the nanofibers uniformly within the matrix. Extensional flow at different draw ratios (λ) was used to obtain anisotropic nanoreinforced composite (NC) tapes. Dynamic Mechanical Analysis (DMA) showed a dual increase, in storage and loss modulus, with draw ratio. This behavior is attributed to the …

Adaptive Optimal Control Design For Stable Vibration Attenuation Of Active Constrained Layer Damping Beam Structure, Tatyana G. Korotkova-Egan

Theses and Dissertations - UTB/UTPA

Vibration suppression using active constrained layer damping (ACLD) has proven to be an invaluable means for improving the performance of a wide variety of engineering systems. The ACLD creates the hybrid of active and passive damping, attaining favorably high damping characteristics, while at the same time, combines unattractive attributes of both treatments, such as stability sensitivity. Control efforts are needed to achieve an adequate performance of the structures treated with ACLD. The purpose of this research is to investigate theoretically and numerically the adaptive optimal controller of the constrained layer damped beam system, using the classical three-layered distributed-parameter model that …

The Effects Of Nationality In The Intercultural Relationship In A Maquila Environment, Cultural Dimensions A Practical Approach, Daniel Martin Reynoso Ortiz

Theses and Dissertations - UTB/UTPA

The Maquiladora Industry has enhanced economic development in the U.S. and Mexico border region. Initially, investors came to set up assembly lines requiring a small amount of technical skill; however, increases in the technological level of products have created the need for companies to require more technical expertise from their staff. Today, the requirement is for the design or redesign of some of their products and the manufacturing processes required to make these products. This brings managerial problems in dealing with technical people in cross cultural environments. These problems deal with staffing issues such as getting the right people and …

Development Of New Heat Sink Technology For High-Density Microprocessors, Pedro Lopez Jr.

Theses and Dissertations - UTB/UTPA

This study investigates the performance of existing heat sinks and compares it with two heat-exchanger prototypes: aluminum-foam heat sink and PCM (phase-change material)-filled heat sink. Kapton flexible heaters are used to replicate the heat produced by a computer's CPU (central processing unit). A number of thermocouples are connected between the heater and the heat sink being used to measure the component's temperature. The thermocouples are also connected to a data acquisition card to collect the data using a LabVIEW program. The values obtained are compared to data published in literature to validate the experiments and the setup. This setup is …

Analysis Of Lifting Performance Capacity Through An Integrated Learning Curve Model, Jose Roel Flores

Theses and Dissertations - UTB/UTPA

Physical fitness specific to job demands is necessary for jobs that require moderate or heavy effort. Fitness training is needed not just when a new job is learned but also when an individual has been away from the job for a few weeks and returns to perform the task. The basic problem is to have a good understanding of the dynamics of performance capacities to establish training and retraining regimes to prevent overexertion. To obtain this, a better understanding of the behavior of performance capacity over time is necessary. A performance capacity training regimen was designed for tasks that required …

Analysis Of Performance Capacity Of Hand Grip Through An Integrated Learning Curve Model, Miguel Torres

Theses and Dissertations - UTB/UTPA

There are few activities or work task in the manufacturing industry that does not involve grip strength. That is why it is in the best interest of the manufacturing industry to have an understanding of the optimum grip strength gain capacity over time that would lead to better performance, accuracy and most of all prevent hand grip related injuries. For that reason, this thesis was concentrated in discovering a possible basic working model for estimating grip strength over time for a specific grip strength activity. The first step was to observe the trend characteristics of the strength gain data over …

Expert System Development For Hard Disk Drive Failure Analysis, Fernando Rodriguez Rosas

Theses and Dissertations - UTB/UTPA

The Computer's Hard Disk Drive is a complex high technology device, diagnosis of a failure is difficult even using sophisticated test equipments. These Drives are expensive and returning a new one when it fails within the warranty period is not an option. The failed drive must be tested and repaired. In the repair process the analysis and diagnosis of the failures is a key point in the process where decisions regarding the repair process that the failed Drive will follow. Therefore, there is a requirement to perform an effective analysis and provide an accurate diagnosis. The standard system utilized for …

Human Reliability Analysis In The Performance Of Advanced Cardiac Life Support Tasks, Lucia Veronica Rosas

Theses and Dissertations - UTB/UTPA

Error reduction in the performance of medical emergency situations is an area of great concern in today's society. This is specially the case when the situation involves a cardiac arrhythmia. These situations are generally categorized as Advanced Cardiac Life Support (ACLS) events. The American Heart Association provides the proper procedures that practitioners of ACLS should follow to provide care to patients presenting heart arrhythmia problems. These situations occur inside and outside the hospital, outside the hospital being the most critical ones considering the limitation of equipment and availability of qualified care. Errors made by the practitioners of ACLS in this …

Effects Of Diabetes And Aging On Posture And Acceleration Thresholds During Lateral Translations, Samantha Jean Richerson

Doctoral Dissertations

Research objectives. One source of falls in the elderly may be an inability to sufficiently adjust to transient postural perturbations or slips. Identifying useful predictors of fall potential, as well as factors that affect the ability of an individual to detect a movement of the standing support surface may provide insight into postural stability and methods to increase stability in elders. To do this, acceleration thresholds to short, precise, lateral platform translations and the resultant psychophysical responses of adults with early Type 2 diabetes to age-matched controls and young adults were measured.

Methods. Using an innovative SLIP-FALLS platform, …

Microreactor System With Immobilized Enzyme On Polydimethylsiloxane (Pdms) Polymers, Zonghuan Lu

Doctoral Dissertations

Microsystems, specifically microreactors, open the gate to new, improved analytical techniques while offering many advantages for a large number of applications in chemical engineering, pharmacy, medicine, and biotechnology. This study explored the feasibility of fabrication of microreactors using polydimethylsiloxane (PDMS) as a support for enzyme immobilization. Urease enzyme was used for catalyzing the conversion of urea to ammonia.

PDMS (polydimethylsiloxane) is a silicone-based elastomeric polymer. Traditional micromanufacturing technology was employed for reactor mold fabrication. The mold was fabricated based on photolithography techniques, and SU-8 photoresist was used to construct reactor structure templates. The resulting silicon-wafer based reactor molds were then …

Selected Chemoautotrophic Processes In Wastewater Treatment: Low Temperature Nitrification Inhibition By An Azo Dye And Biofiltration For Odor Control Of Hydrogen Sulfide, Ronald W. Martin Jr.

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

Biochemical processes by chemoautotrophs such as nitrifiers and sulfide and iron oxidizers are used extensively in wastewater treatment. The research described in this dissertation involved the study of two selected biological processes utilized in wastewater treatment mediated by chemoautotrophic bacteria: nitrification (biological removal of ammonia and nitrogen) and hydrogen sulfide (H2S) removal from odorous air using biofiltration.

A municipal wastewater treatment plant (WWTP) receiving industrial dyeing discharge containing the azo dye, acid black 1 (AB1) failed to meet discharge limits, especially during the winter. Dyeing discharge mixed with domestic sewage was fed to sequencing batch reactors at 22oC and 7oC. …

Reaction Control In Quiescent Systems Of Free-Radical Retrograde-Precipitation Polymerization, Vijaya Raghavan Tirumala

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

Free-radical retrograde-precipitation polymerization, FRRPP in short, is a novel polymerization process discovered by Dr. Gerard Caneba in the late 1980s. The current study is aimed at gaining a better understanding of the reaction mechanism of the FRRPP and its thermodynamically-driven features that are predominant in controlling the chain reaction.

A previously developed mathematical model to represent free radical polymerization kinetics was used to simulate a classic bulk polymerization system from the literature. Unlike other existing models, such a sparse-matrix-based representation allows one to explicitly accommodate the chain length dependent kinetic parameters.

Extrapolating from the past results, mixing was experimentally shown …

Switching Decisions For Diversity Antennas Using Autoregressive Techniques, Sebastian Mani Puthenpurayil

Theses and Dissertations - UTB/UTPA

Decision-making on switching for diversity antennas has been given considerable attention in recent times in mobile radio communications. Due to multipath propagation of radio waves the signals undergo a phenomenon known as fading and there will be considerable reduction in the average signal strength. By having multiple antennas in the receiver or transmitter the signal strength can be improved by switching back and forth to the antenna that has the maximum signal strength. In this thesis we have used linear prediction method for making decisions on which antenna gives the maximum signal strength. Linear prediction is applied on a single …

Modular Machine Learning Methods For Computer-Aided Diagnosis Of Breast Cancer, Mia Kathleen Markey '94

Doctoral Dissertations

The purpose of this study was to improve breast cancer diagnosis by reducing the number of benign biopsies performed. To this end, we investigated modular and ensemble systems of machine learning methods for computer-aided diagnosis (CAD) of breast cancer. A modular system partitions the input space into smaller domains, each of which is handled by a local model. An ensemble system uses multiple models for the same cases and combines the models' predictions.

Five supervised machine learning techniques (LDA, SVM, BP-ANN, CBR, CART) were trained to predict the biopsy outcome from mammographic findings (BIRADS™) and patient age based on a …