Engineering Commons^™

Application Of Solar Water Heaters For Industrial Use, Lucas T. Atkins

Theses and Dissertations

Solar water heating is a technology that is mainly used for domestic water heating in residential homes. In most applications, the idea is to make a home “off the grid” in that there is no requirement for outside infrastructure or need for energy utility to provide power to this home. This falls in line with the trend of “going green” in an effort to reduce energy use, increase efficiency, or reduce emissions and other harmful byproducts.

This technology can be adapted to reduce the energy costs of industrial manufacturing plants. By eliminating the need for certain sections of a process …

Graphene-Fibers Hybrid Structures As Adsorbents For Heavy Metal Ions In Aqueous Solutions, Dulce C. Capitanachi

Theses and Dissertations

The project focuses on the study of graphene-fiber hybrid structures for adsorption of heavy metal ions in aqueous solutions. Polyvinyl alcohol-based graphene–fiber structures were created using centrifugal spinning and a carbonization process.

Characterization methods of the graphene–fiber hybrid structures (GFHS) include SEM, FTIR, TGA, and EDX. Single-step batch-type adsorption studies were performed to analyze the interaction of Cu (II) and Pb (II) ions onto GFHS surface. Different heavy metal ion concentrations were used, as well as a variation of pH values. Elemental analysis of the adsorbent’s surface after filtration experiments was studied by EDX and spectroscopy to verify the presence …

Design And Testing Of A Modular Laser System With Laser Machining And Bioprinting Capabilities, Jesus Gonzalez

Theses and Dissertations

This thesis introduces the applications of ultrafast lasers while focusing on their bioprinting capabilities. A custom system was designed to utilize a femtosecond laser for 2D and 3D applications. The characteristics of lasers allow them to be efficiently used in machining, 3D printing, research, and more. Their power and precision allow them to be used for delicate work such as bioprinting. Bioprinting is a field holding great potential to benefit society. Studies conducted over the years prove its usefulness in printing cells and biomaterials, while showing there is still much to improve upon before being able to print fully functioning …

Evaluation Of The Most Significant Factors Influencing The Production Rates Of Highway Construction Activities, Angelica M. Neira

Theses and Dissertations

The utilization of realistic production rates is key for the accurate estimation of the contract time in highway projects. Several factors have an impact on production rates and change the total duration of construction projects. To organize and complete projects in a timely, quality and financially responsible manner, projects need to be scheduled carefully. Schedulers and planners of the Texas Department of Transportation (TxDOT) have been noticing that the estimated timelines are far from the reality and want to investigate if external factors can be the cause of this discrepancy. Some of the factors considered in this study are the …

An Advanced Approach For Contract Time Determination In Highway Projects, Cuauhtemoc Torres Cantu

Theses and Dissertations

In project management, finishing a project on schedule is one of the most important aspects. The Texas Department of Transportation (TxDOT) has been experiencing delays in some projects that can be accounted to an inaccurate project time estimation process. This research presents the development of a user-friendly and comprehensive computer-based contract time determination system. The enhanced system implements probabilistic scheduling techniques such as Program Evaluation and Review Technique, and Monte Carlo Simulation. Additionally, the application of a lognormal two-point PERT method is explored in this study. The new system proposes the use of a database of production rates based on …

Energy Harvesting Techniques To Power Onboard Railway Bearing Condition Monitoring Systems, Jacob Nathaniel Bensen

Theses and Dissertations

Limitations of the standard wayside hotbox detection system as a method to identify failing railway bearings severely inhibit the reliability and safety of rail transport. An onboard bearing condition monitoring system would address and ameliorate the issues present in the current detection system. The onboard system would provide more frequent and reliable information regarding bearing condition. For the system to succeed in reducing maintenance time and preventing bearing failure, a method of providing the system with sufficient energy to power its instrumentation is necessary. The instrumentation location environment poses a significant challenge. The device must be placed on the steel …

Parametric Study Of Selective Laser Alloying Of Elemental Titanium And Boron Powders Using An Automated Deposition Mechanism, Julian V. Gonzalez

Theses and Dissertations

An automatic powder deposition and leveling mechanism was designed and constructed to assist in surface roughness experiments for titanium-boron samples. Previously developed energy models and x-ray diffraction analysis was used to confirm the creation of titanium diboride samples. To study TiB2 at different energy values, a 52 (2 factors, 5 levels) factorial design was used and carried out under an argon atmosphere, through the AM250 laser melting system. Two experimental runs were carried out and a total of 50 samples were assigned a surface roughness measurement through the Dektak XT profilometer. Graphically and with statistical analysis, the data was determined …

A Study Of Human Balance And Coordination Using A Head Mounted Display, Daniel Gracia De Luna

Theses and Dissertations

Virtual Reality (VR) is growing with new technologies and applications. The new technologies help the user to feel more immersed in virtual environments, but interaction and immersion is an area that has not been well studied. Immersion is the feeling and reaction of users while they are in a virtual environment. This investigation is focused on the study of the human balance and coordination when human subjects are inside a virtual environment. Over 60 subjects are studied under an experiment, where their trajectory is captured and analyzed to identify possible differences or similitudes between male and female subjects.

Electrostatically Actuated Double Wall Carbon Nanotubes To Include Intertube Van Der Waals Forces, Ezequiel Juarez Ocanas

Theses and Dissertations

This work deals with the amplitude-frequency and amplitude-voltage responses of parametric and primary resonances of electrostatically actuated double-walled carbon nanotubes (DWCNTs). Nonlinear forces acting on the DWCNT are intertube van der Waals and electrostatic forces. Soft AC excitation and small viscous damping are assumed. In coaxial vibration, the outer and inner carbon nanotubes move together (in-phase), maintaining their geometric concentricity; while in noncoaxial vibration, the CNTs move in opposite direction (out-of-phase). Modal coordinate transformation is formulated. The Harmonic Balance Method (HBM) is used to find the free response solutions of the DWCNT. The Reduced Order Model (ROM) method is also …

Assessment Of Some Of The Common Practices Used In Scheduling Highway Projects, Jennifer Reyes

Theses and Dissertations

There are several factors documented in the literature that can affect the accuracy of estimated project durations in highway construction, such as weather, location, and soil conditions. Recently, the Texas Department of Transportation (TxDOT) raised a concern regarding some of the practices used when estimating the contract time for projects. This research presents an assessment of the effect that two practices identified have on the estimated project duration. These two practices include: 1) the estimated lead/lag times in project schedules and 2) scheduling with only critical or controlling activities. The effect of these practices is measured, primarily, by using four …

An Experimental Study Of Thrust Augmentation With Asymmetrical Nozzle Driven Pulsed Ejector, Orlando Rodriguez

Theses and Dissertations

With the emergence of V/STOL vehicles and unmanned aircrafts has come the resurgence of thrust augmentation through an ejector. The use of an ejector has many benefits such as being lightweight and simple design to manufacture. In this study a hot steady jet and a cold steady/unsteady jet was tested. The hot steady jet was produced by a JetCAT PX-180 rxi with a two-inch diameter nozzle exit. The hot steady jet was compared to the cold free steady and unsteady cases. The cold jet was tested under free steady and unsteady condition, as well as steady and unsteady ejector conditions. …

Development Of Prognostics Techniques For Surface Defect Growth In Railroad Bearing Rolling Elements, Nancy De Los Santos

Theses and Dissertations

One of the major causes of failure in railroad bearings used in freight service is rolling contact fatigue (RCF). RCF is due to subsurface inclusions which are a result from impurities in the steel that is used to fabricate the bearings. Once the bearings initiate subsurface fatigue cracks, they will then propagate upward and initiate spalling of the rolling surfaces. These spalls will begin small and continuously propagate with operation as this induces additional crack forming and spalling. Studies have indicated that bearing temperature is not a good indicator of spall initiation. In many cases, the temperature of the bearing …

Experimental Study Of Condensation In Different 3d Printed Regenerators In A Thermoacoustic Cooler, Aibek Bekkulov

Theses and Dissertations

Thermoacoustics (TA) deals with the conversion of heat into sound and vice versa. Device that converts heat into acoustic work is called TA heat engine, while the device that transfers energy from a low temperature reservoir to a high temperature one by utilizing acoustic work is called TA cooler. A simple construction of TA cooler includes an acoustic speaker, a resonator tube and a regenerator stack in which the temperature gradient is being imposed. Such a TA cooler has several advantages over traditional compression/expansion cooling machine such as its simplicity of the construction, high reliability and lack of toxic refrigerants. …

Biomechanics Of Lower Limb During The Golf Swing Using Opensim Modeling, Andrew B. Butler

Theses and Dissertations

The purpose of this research is to investigate the biomechanics of the lower-limb using an inverse dynamics model. Experimental data, recorded by an integrated Motion Analysis – Force Plate System in the UTRGV Biomechanics Laboratory, is used to determine ground reaction forces and marker trajectories. OpenSim, a graphical musculoskeletal and computational platform, is used to model the body in three dimensions. The human body is modeled as a 12-segment linkage, consisting of 23 degrees-of-freedom and 92 muscles. The experimental data for the Biomechanics Laboratory is imported in OpenSim. Then, joint angles, generalized coordinates & accelerations of lower-limb segments, muscle forces, …

Security Assessment Of Select Computer Systems Under Distributed Denial Of Service Attacks Performed By Botnets, Hugo Armando Herrera Martinez

Theses and Dissertations

With the passage of time Internet connectivity has been found on more electronic devices than in previous decades. This continuous development may be perceived as a double-edged sword. While the world becomes more Internet-connected and quality of life increases, the lack of proper security protocols in some of these electronic devices permits illegitimate parties to take control of them for their own malicious purposes.

This thesis studies the impact of compromised Internet-connected devices on commonly used server operating systems: Microsoft’s Windows Server 2012 R2 Datacenter, Windows Server 2016 Datacenter, and Apple’s macOS 10.13.6 High Sierra deployed on Apple’s Mac Pro …

Development Of Flexible Photo-Mechanoluminescent Polymeric Based Systems, Carlos Hernandez

Theses and Dissertations

The project focuses on the creation of nanofiber systems with enhanced photo-mechanoluminescent response and high mechanical flexibility to further enhance promising optical applications. Lanthanide-Polyvinyl Di-Fluoride fiber systems were created using centrifugal spinning and characterized using SEM, FTIR, XPS, DSC, XRD, and PL. Fibers luminescence response was gotten when induced by ultraviolet light and the application of an impact force.

Polymeric Pvdf Fibers For Piezoelectric Applications In Energy Harvesting, Misael E. Martinez

Theses and Dissertations

This work focuses on developing and characterizing the piezoelectric response of Cerium doped Polyvinylidene Fluoride (PVDF) fine fibers and the effects of dopants and alignment on the formation of the β-phase and consequently on the piezoelectric performance. Six sets of fiber mats were prepared varying the concentration (2.5–7.5wt%) of Cerium (III) Nitrate-Hexahydrate and Ammonium-Cerium (IV) Sulfate-Dihydrate. Fiber mats were developed using the Forcespinning® technique and the angular velocity and dopant concentration were adjusted to obtain a synergy between fiber yield and fiber diameter. Fourier Transform Infrared Spectroscopy showed a significant enhancement in the PVDF β-phase and inhibition of the non-polar …

Dehumidification Water Quality Analysis Of The South Texas Gulf Of Mexico, Erik Esteban Castillo

Theses and Dissertations

This project is to introduce a new methodology for environmental research that analyzes humidity from a water treatment perspective. This is done by using a household dehumidifier, which extracts the excess humidity in a given space, to harvest the samples. The dehumidifier was used outside to act as an Atmospheric Water Generator (AWG), which is the process of extracting water from the atmosphere. When AWG is placed near shoreline, then it's classified as a Desalinated Atmospheric Water Generator (DAWG) since it extracts distilled seawater water-vapors. The methodology for DAWG analyzed turbidity in the humidity on SPI, indicating to meet {<.15} TCEQ turbidity water quality standard. The turbidity also showed to have an adverse relation to weather conditions. There is an open market in research on this topic, where the methodology for DAWG can offer answers. This project identifies DAWG as being a sustainable source of potable water for a municipality.

Blockchain Technology Based Supply Chain Systems And Supply Chain Performance: A Resource-Based View, Madhavi Latha Nandi

Theses and Dissertations

Blockchain technology (BCT) is set to transform firms’ present ways of managing supply chains. This thesis explores how the efforts by firms to integrate BCT into their supply chain systems and activities, can enable certain supply chain capabilities and subsequently, improve supply chain performance. Using an abductive research approach, qualitative content analyses of 126 cases of firms’ efforts in BCT-based supply chain systems (BCT-SCS) across multiple industries are conducted to identify the BCT-enabled supply chain capabilities and their performance outcomes. Findings reveal that the present BCT-SCS efforts are mainly oriented towards improving the operational-level capabilities namely, information sharing and coordination …

Secondary Resonances Of Electrostatically Actuated Mems Cantilevers, Christopher I. Reyes

Theses and Dissertations

In this work the behavior of micro-electromechanical (MEMS) cantilever resonators is investigated. The cantilever resonators are electrostatically actuated with hard AC voltage resulting in nine distinct resonances cases including super and subharmonic resonances. The amplitude frequency and amplitude voltage bifurcation diagrams are obtained for each of the nine resonance cases. Reduced order models (ROMs) are developed to include one and two modes of vibration. Three different methods are used to solve the ROMs namely 1) the method of multiple scales (MMS), which is a perturbation method used for one mode of vibration, 2) the homotopy analysis method (HAM), which is …

An Evaluation Of Wastewater Pumping Station Facilities Using Statistical Techniques In Analyzing Each For Rehabilitation Design And To Improve The Adverse Environmental Affects, Zenaida S. Guerrero

Theses and Dissertations

The objective of this research project is to develop two evaluation models, one using excel to provide a design criterion for wastewater pumping stations in collecting design parameters and information effecting efficiency and performance of the pumps. Secondly, to develop a linear regression model for these parameters giving a correlation between dependent and independent variables to verify adverse environmental aspects. This study is based in the City of Weslaco, pertaining to the north waste watershed. The parameters collected are age, efficiency, service area, total dynamic head, existing conditions, monthly sanitary sewer over flow work orders, precipitation data, population by service …

Design Of A Bedside Walker-Cane Hybrid To Aid Senior Adults Avoid Falls During Night Walks, Jorge L. Gutierrez

Theses and Dissertations

The objective of this research and development work is to design a device to help senior adults prevent fall during night walks indoors. The problem of elders falling at a night setting was found to be caused by the multiple environmental and medical conditions. The target demographic was found to be seniors from age 65 and older. Several occupational therapists and two physical therapists were consulted to gain knowledge on elders' behavior, possible improvements on current existing devices, and feedback regarding the early prototype built. Several products and patents were researched with a lack of findings on similar products that …