Engineering Commons^™

An Improved Contact Method For Multi-Material Eulerian Hydrocodes, Kenneth Cline Walls

All ETDs from UAB

Realistic and accurate modeling of contact for problems involving large deformations and severe distortions presents a host of computational challenges. Due to their natural description of surfaces, Lagrangian finite element methods are traditionally used for problems involving sliding contact. However, problems such as those involving ballistic penetrations, blast-structure interactions, and vehicular crash dynamics, can result in elements developing large aspect ratios, twisting, or even inverting. For this reason, Eulerian, and by extension Arbitrary Lagrangian-Eulerian (ALE), methods have become popular. However, additional complexities arise when these methods permit multiple materials to occupy a single finite element. Multi-material Eulerian formulations in computational …

Constant Pv Output By Using Dual Converters For Dc Application, Abdullah Masoud Alghamdi

All ETDs from UAB

The energy from solar panels can be improved to extract more power by using DC-DC converters operating in continuous mode. DC-DC converters which generate fixed DC voltage were selected to observe the photovoltaic operation at maximum power point (MPP). In this thesis, a boost converter and a buck converter are cascaded to step-up then step down voltage from a photovoltaic (PV) array with changeable voltage, irradiance, and temperature, to a 24 V DC. The filtering parameters of the converter were computed and the means which is used as a switch is a metal oxide semiconductor field effect transistor (MOSFET) with …

Design Of A Compact, Fully-Autonomous 433 Mhz Tunable Antenna For Wearable Wireless Sensor Applications, John Buckley, Kevin Mccarthy, Domenico Gaetano, Loizos Loizou, Brendan O'Flynn, Cian O'Mathuna

Articles

The authors present the design of a tunable 433 MHz antenna that is tailored for wearable wireless sensor applications. This study first presents a detailed analysis of the measured impedance characteristics of a chosen antenna under test (AUT) in varying proximity to a human test subject. Instead of limiting the analysis to the head and hand only, this analysis measures the AUT impedance at varying distances from 11 different body positions. A novel antenna equivalent circuit model is then developed that enables both the free-space and total on-body AUT impedance variation to be rapidly computed using a circuit simulator instead …

Low Trade-Off Security Schemes To Detect And Neutralize Malicious Modifications In Nano-Cmos Based Integrated Circuits, Nagendra Gunti

All ETDs from UAB

Security of Integrated electronics is threatened by the vulnerabilities such as the globalization of the Integrated Circuits (ICs) industry, where a computing chip can be manufactured anywhere in the world. Without trusted foundries, the systems they de- velop cannot necessarily be expected to perform as specified due to the susceptibility to attack by a malicious adversary. The threats which arise from malicious modifica- tions to the IC based computing hardware, can disable the system, leak information or produce malfunctions and also provide a back door entry to embedded systems like Cy- ber Physical System (CPS) or can even deny providing …

A Transfer Matrix Approach To Aid In The Design And Optimization Of Hybrid Advanced Passive Structures For Enhancing Photovoltaic Efficiency, James Walshe, Sarah Mccormack, Hind Ahmed, John Doran

Conference Papers

The addition of a luminescent down-shifting (LDS) layer directly onto a photovoltaic (PV) cell introduces additional loss mechanisms within the system. The combination of non-ideal photo-luminescent materials encapsulated within a limited range of viable host materials, with the increased reflection losses arising from the newly created interface represent losses which must be overcome for LDS to offer an enhancement to the underlying cells efficiency. Exploiting the interaction between the highly enhanced electric fields established close to a metal nanoparticles (MNP’s) surface is one route aimed at mitigating the poor optical properties of the luminophore-host combinations available. Alternative approaches, aimed at …

Calculating The Envelope Correlation Coefficient Directly From Spherical Modes Spectrum, Adam Narbudowicz, Max Ammann, R. Cornelius, D. Heberling

Conference Papers

This paper proposes an improved technique to calculate the Envelope Correlation Coefficient (ECC) by directly using the spherical mode spectrum of the antenna under test. The technique avoids errors due to numerical pattern integration and simplifies post-processing for near-field measurements. The technique is successfully tested on two different antenna types, in the total number of four MIMO configurations.

Electrically Small Antenna With Switchless Pattern Reconfiguration, Adam Narbudowicz, Max Ammann, Dirk Heberling

Conference Papers

An electrically small pattern reconfigurable antenna is proposed. It allows adjustment of the radiation pattern by applying a phase shift between its two ports. The structure is a cylinder with λ/5 diameter. Simulated results show good operation at 2.44 GHz and three different radiation patterns are demonstrated by applying three different phase shifts. The antenna's principles of operation and limitations are explained based on the theory of spherical modes.

Easy-To-Deploy Lc-Loaded Dipole And Monopole Antennas For Cubesat, Korbinian Schraml, Adam Narbudowicz, Suramate Chalermwisutkul, Dirk Heberling, Max Ammann

Conference Papers

This paper proposes a new approach to reduce weight and complexity of VHF/UHF cubesat antennas by utilizing a dual band antenna, rather than standard two-antenna system routinely implemented in cubesats. Three systems are compared: A standard system with separate transmit/receive dipoles, a dual-band dipole for both transmit and receive and a dual-band monopole, which uses the body of 1U cubesat (10 × 10 × 10cm) as a “groundplane”. Additionally it is demonstrated that with appropriate feed the dipole might be used in monopole configuration in case of deployment system malfunction.

Axial Ratio Correction For Gnss Antennas In Asymetrically Coupled Environments, Adam Narbudowicz, Max Ammann, Dirk Heberling

Conference Papers

The paper demonstrates a technique to correct the axial ratio of dual-fed circularly-polarized antennas in the presence of strong coupling with surrounding components or asymmetrically reduced ground plane. It demonstrated - based on a standard GPS L1 patch antenna - that for certain situations a phase shift of up to 135° may be beneficial compared to the routinely used 90°, allowing for AR improvement from 7.8 dB (for 90°) to 2.1 dB (135°).

Object Detection And Path Detection System For Autonomous Terrain Vehicles, Avinash Kumar Singh

All ETDs from UAB

Every year’s thousands of people died in road accidents worldwide. The autonomous vehicles provide a better solution for this kind of situations. The autonomous vehicles move freely in an outer environment and perform different types of tasks according to the condition. The moving object detection in real time and perform the action are always considering important part in autonomous vehicles. To demonstrate the concept of the autonomous vehicle, we design an autonomous all-terrain vehicle model. In this thesis, we used the two types of distance measurement sensors i.e. Ultrasonic and Sharp Infrared sensors. These sensors are connected to the Arduino …

Experiences Of Public Agency Managers When Making Outsourcing Decisions, Shakeel Baig

Walden Dissertations and Doctoral Studies

Managers in state transportation agencies in the United States must frequently choose between using the talents and abilities of in-house staff or outsourcing for road and bridge design projects. Budgetary crises have strongly affected funding for transportation infrastructure. Facing budgetary pressures to suppress costs, managers must frequently make the choice of outsourcing a project or performing it in-house. Yet, decision-making models for these decisions are inadequate. The purpose of this phenomenological study was to explore and describe the lived experiences of public agency managers when making decisions to outsource the core government functions such as road and bridge design projects. …

Scheduling Strategies For Construction Project Managers Toward On Time Delivery, Paul Shamp

Walden Dissertations and Doctoral Studies

Construction management projects involve complex, dynamic environments resulting in uncertainty and risk, compounded by demanding time constraints. Research indicated project managers have struggled to identify best practices for scheduling construction projects via critical path methodologies while searching for tools to increase timely job completions and budget profits. The purpose of this single case study was to explore the strategies that construction project managers used to manage scheduled construction project delivery on time. The constructivist philosophical worldview was used as the framework for this study. Data were collected from semistructured interviews from 7 project managers from 5 different construction companies selected …

Reconceptualizing Pedagogical And Curricular Knowledge Development Through Making, Steven Greenstein, Justin Olmanson

Department of Teaching, Learning, and Teacher Education: Faculty Publications

While making is typically tethered to narratives of entrepreneurship and business, it can provide a gateway to meaningful interaction and deepened understanding of both content and pedagogy. In this article we provide descriptions of two courses—one each at the pre-service and in-service levels—that engage teachers in making and design practices that we hypothesized would inform their pedagogical and curricular thinking. With a focus on the design of new tools to support teaching and learning through the use of human-centered design practices and digital fabrication technologies, these courses have teachers exploring at the intersection of content, pedagogy, and making. Specifically, they …

Characterization & Extraction Of Extracellular Matrix From Porcine Adipose Tissue, Rahulkumar Kantibhia Bhoi

Open Access Theses & Dissertations

Tissue in particular extracellular matrix(ECM) plays a vital role in the growth and the function of each cell types and promote tissue regeneration and repair an impair organs. Many techniques have been developed so far to decellularized porcine tissue for the purpose to use as regenerative medicine and in tissue engineering. We aimed to optimized a method to decellularized porcine tissue while effectively eliminating xenogeneic epitopes, lipids and to retain necessary component of it intact without disrupting ECM. We have developed 2-week protocol to optimize well preserved ECM component that may keep xenogeneic biomaterial for tissue engineering and regenerative medicine. …

Theoretical Acoustic Absorber Design Approach For Lox/Lch4 Pintle Injector Rocket Engines, Jonathan Candelaria

Open Access Theses & Dissertations

Liquid rocket engines, or LREs, have served a key role in space exploration efforts. One current effort involves the utilization of liquid oxygen (LOX) and liquid methane (LCH4) LREs to explore Mars with in-situ resource utilization for propellant production. This on-site production of propellant will allow for greater payload allocation instead of fuel to travel to the Mars surface, and refueling of propellants to travel back to Earth. More useable mass yields a greater benefit to cost ratio. The University of Texas at El Paso's (UTEP) Center for Space Exploration and Technology Research Center (cSETR) aims to further advance these …

Studies On Woven Carbon/Vinyl Ester Composites: Environmental Effects, Joining And Hybridization, Ricardo Garcia

Open Access Theses & Dissertations

The incessant demand for fiber reinforced polymer composites, or FRPCs, in industrial applications which desire materials that possess high strength-to-weight ratios, generates a theory-to-practice void which must be filled with scientific research. In this Thesis, woven carbon/vinyl ester composites are studied under a wide spectrum of settings and conditions. The adverse effects of sea water environment and arctic temperatures on such mentioned composites are explored in the form of moisture uptake, impact on flexural modulus, strength and structural damage. It was found that sea water saturation in general degrades the flexural strength up to 19.45%, and arctic exposure and combined …

Compressive Vector Reconstruction: Hypothesis For Blind Image Deconvolution, Alonso Orea Amador

Open Access Theses & Dissertations

Alternative imaging devices propose to acquire and compress images simultaneously. These devices are based on the compressive sensing (CS) theory. A reduction in the measurement required for reconstruction without a post-compression sub-system allows imaging devices to become simpler, smaller, and cheaper. In this research, we propose a new algorithm to compress and reconstruct blurred images for CS imaging devices. Blur effect in images is common due to relative motion, lens, limited aperture dimensions, lack of focus, and/or atmospheric turbulence. Our intention is to compress a blurred image with CS techniques and then reconstruct a blur-free version using the proposed algorithm. …

Structural And Electrical Characterization Of Tin Oxide Resistive Switching, Arka Talukdar

Open Access Theses & Dissertations

Resistive switching in metal oxide is a phenomenon in which the metal oxide changes its resistance upon application of electric field and thus giving two states; high resistance state (HRS) and low resistance state (LRS). Many metal oxides have been investigated however very little is known about unipolar resistive switching in SnO2 though it has shown excellent resistive switching characteristics. Defects in the material play a vital role in resistive switching of the metal oxides. In this work, the role of defects in resistive switching of SnO2 are investigated in Ti/SnO2/Au structures. Two methods were used to control the concentration …

Redesign Of A Volume Adjustable Transtibial Prosthetic Socket, Samuel Terrazas Quezada

Open Access Theses & Dissertations

Recent research and development in prosthetics have aimed at improving socket designs and components to mimic more efficiently the human body. One such innovation is the Aperture Socket, a low-cost volume adjustable prosthetic socket. During the validation stage of its development, the Aperture Socket successfully demonstrated that it could compensate for volume changes, but various improvements on use and comfort were identified. This project develops and tests a redesign of the Aperture Socket previously developed for amputees in developing countries and subsequently patented and licensed to LIMBS International, Inc.

The first phase of this study was the creation of various …

Image Data Mining For Quality Control Of Nanofiber Reinforced Piezoelectric Nanocomposites Based On Sem Images, Zhonghua Hu

Open Access Theses & Dissertations

Recently, portable and wireless nano-scaled devices have been widely used in environmental monitoring, medical implants, defense technology, industrial safety, and personal electronics, such as the nanowire-based gas and chemical sensors and programmable nanowire circuit for nano-processors. There has been an increasing demand for high energy density capacitors that can be engineered for various applications in advanced devices. In it, piezoelectric nanofiber materials play critical role in producing new products. A piezo-ceramic polymer composite contains a polymer of high dielectric strength and high permittivity ceramic inclusions, making it well suited as a high energy density capacitor. Furthermore, the research shows that …

Renewable Energy Systems Optimization Using Monte Carlo Simulation And Evolutionary Algorithms, Nicolas Lopez

Open Access Theses & Dissertations

This Dissertation explores the Renewable Energy Integration Problem, and proposes a Genetic Algorithm embedded with a Monte Carlo simulation to solve large instances of the problem that are impractical to solve via full enumeration. The Renewable Energy Integration Problem is defined as finding the optimum set of components to supply the electric demand to a hybrid

microgrid. The components considered are solar panels, wind turbines, diesel generators, electric batteries, connections to the power grid and converters, which can be inverters and/or rectifiers. The methodology developed is explained as well as the combinatorial formulation. In addition, 2 case studies of a …

Design And Development Of A Foil Application Tool For A Foil Embedding Process In The Multi3d Manufacturing System, Betty Elizabeth Mckenzie

Open Access Theses & Dissertations

Additive manufacturing (AM) encompasses different technologies, including material extrusion 3D printing, a technology commonly referred to as fused deposition modeling (FDM), which is the focus of the work described in this manuscript. Additive manufacturing is a growing technology with many applications in numerous fields from the air force to medical offices. FDM is a process that uses thermoplastics, in this case polycarbonate (PC), where the PC is heated and selectively dispensed in a layer-by-layer process to create a 3D printed part. Currently, FDM systems have advantages over subtractive manufacturing or machining because cavities and other components (e.g., microchips, valves, and …

Development And Verification Of A Lab-Scale Green Propellant Hybrid Motor System, Shyamal Patel

Open Access Theses & Dissertations

Hybrid rocket propulsion offers the potential to combine advantages of both solid and liquid propellant systems, but low regression rates hinder their practicality. The suggested use of hydroxylammonium nitrate (HAN) based propellants in hybrids offers the potential for developing high impulse motors with low development and production costs. In this paper, I present the development of a small-scale system used to measure the regression rate of a hybrid motor. The system can accommodate fuel grains 5 cm long with an outer diameter of 6 cm and can implement the various decomposition gases needed for HAN. The motor firings of hydroxyl …

Molecular Dynamics Studies Of Crystal Growth Phenomena In Cdte Based Heterostructures, Rodolfo Aguirre Ii

Open Access Theses & Dissertations

Cadmium telluride (CdTe) is a material used to make solar cells because it absorbs the sunlight very efficiently and converts it into electricity. However, CdTe modules suffer from degradation of 1% over a period of 1 year. Improvements on the efficiency and stability can be achieved by designing better materials at the atomic scale. Experimental techniques to study materials at the atomic scale, such as Atomic Probe Tomography (APT) and Transmission Electron Microscope (TEM) are expensive and time consuming. On the other hand, Molecular Dynamics (MD) offers an inexpensive and fast computer simulation technique to study the growth evolution of …

Evaluation Of Mechanical Parameters Of Contaminated Road Base And Railway Ballast, Prajwol Tamrakar

Open Access Theses & Dissertations

This Dissertation comprises two topics in the area of transportation geotechnics that focus on the evaluation of stiffness parameters of contaminated road base and railway ballast. The abstracts of these two studies are provided in the following two paragraphs.

The performance of a flexible pavement depends on the mechanical characteristics of its unbound granular base layer. The mechanical characteristics such as stiffness and deformation resistance depend on many factors such as the material gradation, fines content, moisture content, physical properties of coarse aggregate and more. The base materials are often contaminated by the excessive fines that is caused by improper …

Design Of A 2000 Lbf Lox/Lch4 Throttleable Rocket Engine For A Vertical Lander, Israel Lopez

Open Access Theses & Dissertations

Liquid oxygen (LOX) and liquid methane (LCH4) has been recognized as an attractive rocket propellant combination because of its in-situ resource utilization (ISRU) capabilities, namely in Mars. ISRU would allow launch vehicles to carry greater payloads and promote missions to Mars. This has led to an increasing interest to develop spacecraft technologies that employ this propellant combination.

The UTEP Center for Space Exploration and Technology Research (cSETR) has focused part of its research efforts to developing LOX/LCH4 systems. One of those projects includes the development of a vertical takeoff and landing vehicle called JANUS. This vehicle will employ a LOX/LCH4 …

Microstructure And Mechanical Properties Of Sputter-Deposited Nanocrystalline W1-Ymoyo3 Thin Films, Gabriel Lopez

Open Access Theses & Dissertations

Currently, there is a wide-spread interest in the design and development of indium (In) free transparent conductive oxides (TCOs) for utilization in photovoltaics and optoelectronics. Tungsten oxide (WO3)-based materials are being explored for their utilization in solar cells, photo-electrochemical cells (PECs), electrochromic (EC) "smart windows," information displays, variable reflectance mirrors, and photo-detector materials. Designing ternary compounds or composite/hybrid structures coupled with tailoring the nano-architectures of WO3-based materials has been considered to be attractive develop potential candidates with enhanced performance. In this context, in this Thesis work, an attempt is made to prepare W-Mo-O nanocomposite films, which can be considered as …

Classification Of Radar Jammer Fm Signals Using A Neural Network Approach, Ariadna Estefania Mendoza

Open Access Theses & Dissertations

A Neural Network (NN) used to classify radar signals is proposed for the purpose of military survivability and lethality analysis. The goal of the NN is to correctly differentiate Frequency-Modulated (FM) signals from Additive White Gaussian Noise (AWGN) using limited signal pre-processing. The FM signals used to test the NN approach are the linear or chirp FM and the power-law FM. Preliminary simulations using the moments of the signals in the time and frequency domain yielded better results in the frequency domain, suggesting that time domain training would not be as effective frequency domain training. To test this hypoThesis, we …

Design And Development Of A Delivery System For Green Ionic Monopropellants And Testing Of A 22n Thruster, Jaclyn Mona Mejia

Open Access Theses & Dissertations

LMP-103S and AFM-315E are emerging propellants that are less toxic to the environment than the propellants currently being used in spacecraft propulsion. Both propellants are a blend of liquid fuel, oxidizer and a majority percent of water. The diluted solutions enable the capability to handle and store the propellants with fewer requirements; for this reason, it decreases the overall cost of the propellants since it needs less precautions. The Missile Defense Agency (MDA) awarded the University of Texas at El Paso (UTEP) a contract to further research green propellants and eventually replace Hydrazide.

Healthcare Utilization Awareness And Labor Monitoring Methodology: A Theoretical I.M.S.E. Approach To Risk Minimization And Human Metrics Capturing In The Nursing Workforce, Luis Reyes

Open Access Theses & Dissertations

The healthcare industry is so complex and dynamic that the development of any tool designed to promote positive patient outcomes nearly requires the developer to be an actual healthcare practitioner. Many healthcare tools exists that initially give the perception that there will be no future requirements that may hinder the tools' integrity, but more often than not, the unexpected occurs. The future is one unpredictable element of life that most engineers wish they could capture with optimal precision. I.M.S.E. (Industrial, Manufacturing and Systems Engineering) applications do not assist with fortune telling, but they do assist with creating robust tools designed …