Engineering Commons^™

A Stochastic Approach For Pavement Condition Projections And Budget Needs For The Mtc Pavement Management System, Rafael Arturo Ramirez Flores

Open Access Theses & Dissertations

Pavement management decision-making is the most important task for officials in transportation agencies, who develop maintenance and rehabilitation programs. Information about historical pavement network performance is needed for decision-making; pavement management systems (PMS) provide means to organize road network data to improve the pavement network condition. PMS have prediction performance models to forecast the future condition of the pavement networks with information required for decision-making; these models can be deterministic or probabilistic. Pavement performance deterministic models are commonly used in PMS, but they do not consider the uncertainty in forecasting pavement performance. Pavement performance depends on many random factors like …

Recovery Of Nutrient Nitrogen From Municipal Wastewater Residuals By Gas Membrane Separation, Evelyn Rios

Open Access Theses & Dissertations

There are relatively high amounts of ammonia returned to the headworks of a municipal wastewater plant that are extracted from the dewatering process. This ammonia load contributes to a significant oxygen demand in the secondary treatment, requiring greater air blower energy costs. This goal of this research was to evaluate the feasibility of the recovery of an ammonium sulfate product from belt press filtrate. The objectives of this research were to: (1) analyze wastewater treatment average monthly data flows and constituents with respect to ammonia nitrification, (2) the evaluate the technical performance of a two sage gas-separation membrane for recovering …

Novel Classification Of Slow Movement Objects In Urban Traffic Environments Using Wideband Pulse Doppler Radar, Berta Rodriguez Hervas

Open Access Theses & Dissertations

Every year thousands of people are involved in traffic accidents, some of which are fatal. An important percentage of these fatalities are caused by human error, which could be prevented by increasing the awareness of drivers and the autonomy of vehicles. Since driver assistance systems have the potential to positively impact tens of millions of people, the purpose of this research is to study the micro-Doppler characteristics of vulnerable urban traffic components, i.e. pedestrians and bicyclists, based on information obtained from radar backscatter, and to develop a classification technique that allows automatic target recognition with a vehicle integrated system. For …

Performance Life Of Various Hot Mix Asphalt Mixtures In Texas, Danniel David Rodriguez

Open Access Theses & Dissertations

Typically, pavement engineers in subjectively estimate the service lives of various hot-mix asphalt (HMA) mixtures as part of the life-cycle cost analysis considering the staged design and rehabilitation of flexible pavements. This study proposes the performance lives for the various dense-graded (conventional) mixtures, stone-matrix asphalts (SMA), permeable friction courses (PFC), performance design mixtures and other mixtures placed in Texas. A necessary and significant aspect of the approach involved data mining and merging several pavement management databases (Letting Database, DCIS and PMIS) to obtain mixture longevity data along with historical PMIS information. The product of the linking process resulted in the …

Accuracy And Precision Evaluation Of Traffic Speed Pavement Deflection Devices, Jorge Velarde

Open Access Theses & Dissertations

Pavement structural adequacy is considered an important aspect of the pavement management activities and can be incorporated by using surface pavement deflections. Continuous deflection technology, which has been around for several years, can potentially supplant single point deflection measurements provided by the Falling Weight Deflectometer (FWD). Previous studies have evaluated the traffic speed deflection devices (TSDD) accuracy and precision by comparing their results with FWD measurements. Although appropriate correlations and indices to compensate for the differences in load have been made, a direct comparison under the same loading conditions has not been reported in the literature.

The goal of this …

Development Of A Novel Hybrid Unified Viscoplastic Constitutive Model, Luis Alejandro Varela Jimenez

Open Access Theses & Dissertations

Gas turbines are now days used in power plants for power generation and for propulsion in the aerospace industry. In these applications gas turbines are exposed to severe temperature and pressure variations during operating cycles. These severe operating conditions exposed the turbineâ??s components to multiple deformation mechanisms which degrade the material and eventually lead to failure of the components. Nickel based and austenitic super alloys are candidate material used for these applications due to its high strength and corrosion resistance at elevated temperatures. At such temperature levels, candidate materials exhibit a rate-dependent or viscoplastic behavior which difficult the prediction or …

A Heterogeneous Multiscale Method For Poroelasticity, Paul M. Delgado

Open Access Theses & Dissertations

In this Thesis, we develop and analyze a heterogeneous multiscale model for coupled fluid flow and solid deformation in porous media based on operator splitting and finite volume method. The splitting method results in two elliptic multiscale PDE's in the form of a reaction diffusion equation and a linear elasticity equation. We extend our previous multiscale method from 1D to higher dimensions and develop new approaches for the inclusion of mixed boundary conditions and source terms. We derive an error estimate for our multiscale method and analyze the stability of our splitting method. We also test the effectiveness of our …

Exploratory Study Of Seasonal Indoor Bioaerosols And The Associated Health Outcomes In Low-Income Communities In El Paso, Texas, 2014, Eric Martinez

Open Access Theses & Dissertations

Introduction: Structural degradation, moisture levels, and building failures can influence poor indoor air quality and create a good environment for bioaerosols. People spend much of their time indoors and can potentially be exposed to these bioaerosols. Several studies have correlated exposures to high concentrations of bioaerosols to various health problems, severe allergies, asthma, or other respiratory illness. Objectives: The objectives of this study are to describe bioaerosol concentrations, meteorological factors, and health outcomes during the summer and fall seasons; characterize bioaerosols (bacteria and fungi) collected in low-income communities; compare bioaerosol concentrations by season; compare meteorological factors to bioaerosol concentrations by …

Development Of Rigorous Electromagnetic Simulation Tools For Anisotropic Structures, Jose Luis Enriquez

Open Access Theses & Dissertations

Many times, mankind's creative nature has pushed the envelope beyond what was deemed physically possible at the time. People have engineered ways for us to fly, communicate across the globe in seconds, landed on the moon, and more recently discovered ways to make an object invisible. Unfortunately, there are times that this creativeness is hindered by funding, access to required tools or a combination of both. While this work cannot provide funding, it does provide a tool that one could use to model and simulate a variety of media. The media can vary from devices already being implemented to more …

Skin Detection In Hyperspectral Images, Stephanie Sanchez

Open Access Theses & Dissertations

Hyperspectral imagers collect information of the scene being imaged at close contiguous bands in the electromagnetic spectrum at high spectral resolutions. Hyperspectral images are organized in a data cube where the x and y axes contain spatial information and the z-axis contains spectral information. The number of applications for these imagers has grown over the years as they are now used in various fields (i.e. agriculture, surveillance, chemical imaging, environmental, medical, etc.). Many algorithms are described in the literature for skin detection in color imagery. However increased detection accuracy, in particularly over cluttered backgrounds, and of small targets and in …

Neighbor Discovery In Mobile Ad Hoc Networks, Esau Enrique Ruiz-Gaistardo

Open Access Theses & Dissertations

Neighbor Discovery (ND) is the process that initializes a reliable communication between one-hop neighbors in mobile ad hoc networks (MANETs). This process consists of scheduled exchanges of control messages, called â??Hello Messagesâ?? (HMs) between one-hop neighbors. HMs build bidirectional links that are used to announce the topology information. Each node uses ND and the topology information to populate its routing tables and to communicate with every other node in the network. In MANETs, ND process is a permanent process to discover one-hop neighbors. It is based on two parameters: 1) ND message interval (the period of time in between sending …

Carbon Based Nano-Composite Materials For Energy Storage Applications, Gerardo Rodriguez Melo

Open Access Theses & Dissertations

Energy storage systems and devices are an integral part of advanced electronic technology. Electronic technology is ever-advancing, but in order to do so, it must be supported by all its systems. The energy storage system is one key system that may dictate the performance and limitation of such electronics. Thus, research emphasis on energy storage devices has been on improving the performance of energy storage devices, such as: improved energy and power density, increased stability and cycle life, as well as reduced costs. Lithium-ion-batteries, and supercapacitors offer the potential to meet energy storage demands and to be improved further upon. …

Reaction Of Liquid Aluminium- Samarium Alloys With B4c At Ultra High Temperatures, Sanjay Shantha-Kumar

Open Access Theses & Dissertations

Reactive studies between a packed bed of B4C and Al-Sm-Me (Me = Ti, Zr, Hf) alloy melts were carried out under a pseudo-isopiestic thermodynamic system. A graphite enclosure isolated the system under a temperature gradient with one end reaching temperatures greater than 1800 K and the opposite end of the graphite enclosure contains liquid Al with temperatures approximating 950 K. The liquid Al establishes an oxygen potential to control oxidation of very reactive elements (i.e., Al, Sm and Ti). The Al-Sm-Me alloy infuses into a packed bed of B4C reacting exothermically to form borides and carbides depending on the thermodynamic …

High Temperature Oxidation Of Nb-Cr-Mo-Si-B Alloys, Kathryn S. Thomas

Open Access Theses & Dissertations

It has been the trend to use nickel based superalloys in high temperature applications, however higher temperatures are required in the effort to enhance the efficiency of such components as jet turbine engines. The melting temperature of the nickel based superalloy limits the extent to which temperature can be raised as these materials are typically used at temperatures within 200 degrees of their melting point. Refractory metal based systems are attractive due to their high melting points, low densities, and good high temperature strength. However, in such cases as niobium, poor oxidation resistance limits the widespread use of such alloys. …

Single And Multiple Objective Biomass-To-Biofuel Supply Chain Optimization Considering Environmental Impacts, Claudia Evangelina Valles Sosa

Open Access Theses & Dissertations

Bioenergy has become an important alternative source of energy to alleviate the reliance on petroleum energy. Bioenergy offers diminishing climate change by reducing Green House Gas Emissions, as well as providing energy security and enhancing rural development. The Energy Independence and Security Act mandate the use of 21 billion gallons of advanced biofuels including 16 billion gallons of cellulosic biofuels by the year 2022. It is clear that Biomass can make a substantial contribution to supply future energy demand in a sustainable way. However, the supply of sustainable energy is one of the main challenges that mankind will face over …

Defeating Anisotropy In Material Extrusion 3d Printing Via Materials Development, Ángel Ramón Torrado Pérez

Open Access Theses & Dissertations

Additive Manufacturing technologies has been in continuous development for more than 35 years. Specifically, the later denominated Material Extrusion Additive Manufacturing (MEAM), was first developed by S. Scott Crump around 1988 and trademarked later as Fused Deposition Modeling (FDM). Although all of these technologies have been around for a while, it was not until recently that they have been more accessible to everyone. Today, the market of 3D printers covers all ranges of price, from very specialized, heavy and expensive machines, to desktop printers of only a few cubic inches in volume. Until recently, FDM technology had remained somewhat stagnant …

A Methodology For Physically-Based Contact And Meniscus Properties In Rigid-Body Computational Knee Modeling, Stephen Wilson

Open Access Theses & Dissertations

Determining natural inner knee mechanics is a longstanding goal for researchers with applications to prevention and treatment of knee trauma and osteoarthritis. Physical testing has only provided limited information of knee mechanics due to technical challenges and cost. Modeling has been used for decades to obtain some of this otherwise inaccessible information, and recently finite element analysis (FEA) has become a popular means to this end. However, FEA requires time intensive mesh-creation and has large computational requirements. Ideally, model creation should be easy and simulations should be fast to allow for sensitivity analysis. Although allowing easier model creation and offering …

Modeling Of The Response Of A Memcapacitor For An Impulse, Step, Ramp, And Sinusiodal Inputs, Ghassan Khalil Kachmar

Open Access Theses & Dissertations

Micro-Electro-Mechanical Systems, or MEMS, is a technology of very small scale devices. The dimensions of MEMS can vary from below one micron to several millimeters. MEMS have some mechanical functionalities such as the moving plate of a parallel plate capacitor (memcapacitor). MEMS researchers and developers have demonstrated an extremely large number of microsensors for almost every possible sensing modality including temperature, pressure, inertial forces, and chemical species. The equation of motion of the moving plate of a memcapacitor is governed by a non-linear differential equation with no known exact solution. Most research into determining the theoretical response of a memcapacitor …

Low Power Design Techniques For Data Acquisition, Praveen Kumar Palakurthi

Open Access Theses & Dissertations

Semiconductor technology advancement continues to lead to smaller device geometries. Digital circuits have benefited from the technology scaling whereas analog circuits often suffer in terms of performance and noise immunity. As functionality continues to be integrated onto systems-on-chips, analog circuits consume increasingly more power than digital circuits and the objective of this Dissertation is to explore low power techniques in the context of both digital and analog circuits residing on the same silicon real estate.

As natural signals are in analog form, a necessity exists to convert these into digital form and then back again in order to exploit the …

Spectral Radiation Analysis Of Premixed Oxy-Syngas And Oxy-Methane Flames, Naznin Jahan Afrose

Open Access Theses & Dissertations

Oxy-fuel combustion has potential to be an impeccable enhancement of current combustion techniques. For a hydrocarbon burning with oxygen the resulting exhaust stream is composed mainly of carbon dioxide and water vapor. This exhaust allows for easier carbon capture and sequestration since the water can be condensed out. Another advantage is the significant reduction of NOx since much of the nitrogen found in air-combustion systems is eliminated. These processes also provide a higher theoretical efficiency which is advantageous. Although beneficial many of the exhaust gas products radiative characteristics are unknown. Motivated by this, this paper focuses on the spectral radiation …

Hydrodynamic Cavitation As A Method For Cell Disruption, Christopher Caviglia

Open Access Theses & Dissertations

Development of new renewable technologies is an important driver in the scientific community.

As atmospheric carbon dioxide levels increase and the dependence on a finite amount of fossil fuel remains, the need for sustainable forms of energy is ever growing. Research in the field of renewable biofuels has pointed researchers toward the naturally occurring, robust, lipid- producing microorganism; microalgae. Its ability to sequester carbon and yield high lipid production has made it very attractive to renewable research. It has the potential to produce up to 10 times the oil, per acre, than competing biofuel feedstocks. However, an energy efficient method …

Design And Analysis Of A Novel Latch System Implementing Fiber-Reinforced Composite Materials, Francisco Guevara

Open Access Theses & Dissertations

The use of fiber-reinforced composite materials have increased in the last four decades in high technology applications due to their exceptional mechanical properties and low weight. In the automotive industry carbon fiber have become popular exclusively in luxury cars because of its high cost. However, Carbon-glass hybrid composites offer an effective alternative to designers to implement fiber-reinforced composites into several conventional applications without a considerable price increase maintaining most of their mechanical properties. A door latch system is a complex mechanism that is under high loading conditions during car accidents such as side impacts and rollovers. Therefore, the Department of …

Novel Engineered Nanomaterials For Water Remediation And Gas Adsorption: Graphene Oxide And Carbon Nanotubes Decorated With Metal-Organic Frameworks And Magnetic Nanoparticles, Vahid Jabbari

Open Access Theses & Dissertations

In the current study, a series of novel magnetic and non-magnetic hybrid nanocomposites based on metal-organic frameworks (MOFs) of M3(BTC)2 (M: Ni, Cu, Zn, and Cd), graphene oxide (GrO), and carbon nanotubes (CNTs), and Fe3O4 magnetic nanoparticles (MNPs) were developed via a green, simple and versatile solvothermal method at which GrO and CNT were used as platform to grow the MOFs and Fe3O4 MNPs over them. The as-synthesized nanocomposites were characterized by XRD, SEM, TEM, XPS, IR, Raman, TGA, and N2 adsorption/desorption isotherms. Morphological analysis confirmed successful growth of nano-size Fe3O4 MNPs and M3(BTC)2 MOFs over GrO and CNT platforms. …

A Cell Formation Algorithm For Sequential Processes With Alternative Machine Selection In The Automotive Lighting Industry, Victor Manuel Loya Garnica

Open Access Theses & Dissertations

At the present time, there are more than 12 big companies dedicated to design and produce OEM lighting systems for cars and trucks. The manufacturing processes for headlamps, tail lamps and any other exterior vehicle lighting are very common in the auto industry. Still, every automotive lamp assembly is different from brand to brand and even between the different vehicle models. Indeed, there are car headlamps with less than 30 sub-components and others with up to 300 elements. This implies creating diverse part numbers which share or hold varying manufacturing methods within a specific facility. Management of the plant resources …

E-Quality Design Of Experiments For Structural Electronics, Oscar Murga

Open Access Theses & Dissertations

Additive Manufacturing (AM) is a technology utilized for creating complex parts by adding layers of material in order to create a three dimensional functional part. This technology has been pushed to a new level of functionality where mechanical parts are combined with electronic components to create Three-Dimensional Structural Electronics (3DSE) systems. This new technology has been used to replace Printed Circuit Boards (PCB), for 3D SE are light weight and can be created in any desired shape. Computer Aided Design (CAD) software is used to design the part and a Fused Deposition Modeling (FDM) machine is used to 3D print …

A Methodology For Use Of Digital Image Correlation For Hot Mix Asphalt Testing, Estefany Ramos

Open Access Theses & Dissertations

Digital Image Correlation (DIC) is a relatively new technology which aids in the measurement of material properties without the need for installation of sensors. DIC is a noncontact measuring technique that requires the specimen to be marked with a random speckled pattern and to be photographed during the test. The photographs are then post-processed based on the location of the pattern throughout the test. DIC can aid in calculating properties that would otherwise be too difficult even with other measuring instruments.

The objective of this Thesis is to discuss the methodology and validate the use of DIC in different hot …

A Rapid Approach For Considering Nonlinear Response Of Flexible Pavements Under Fwd And Estimation Of Remaining Lives Of Pavements, Shahabaldin Shirazi

Open Access Theses & Dissertations

Most mechanistic empirical pavement analyses are based on the layered elastic models where the stress sensitivity of geomaterials and their nonlinearity are either ignored or accounted for indirectly. Advanced numerical models, such as finite element models, are required to consider the nonlinear nature of the geomaterials. Existing pavements are often tested with the Falling Weight Deflectometer (FWD) to estimate the input moduli to the layered elastic models in order to estimate remaining life and structural capacity of pavements. It has been more than 30 years that FWD tests are being performed to measure structural adequacy of pavements. Backcalculation is the …

Acoustic Emission Characteristics Of Damage Accumulation In Kevlar® 49 Composites, Eduardo Andrade

Open Access Theses & Dissertations

Acoustic emission (AE) data attained during tensile testing of epoxy impregnated Kevlar® 49 (K/Ep) composite strands were reduced and analyzed to monitor progressive damage accumulation during the approach to tensile failure. The K/Ep material tested in this study was chosen due to its similarity to the material-of-construction used in composite overwrapped pressure vessels (COPVs) used on the NASA Space Shuttle Orbiter. Insight into the progressive microstructural degradation of K/Ep strands was gained by monitoring AE event rate and energy. Source location based on energy attenuation and arrival time data was used to differentiate between significant AE attributable to microstructural damage …

Evaluating Methods Of Field-Based 3d Visualization And Their Application To Mapping Metamorphic Terranes: An Example From The Panamint Mountains, California, Jade Ashley Brush

Open Access Theses & Dissertations

Field geology has traditionally relied on 2D, paper-based workflows, but digital mapping techniques are rapidly replacing these outdated methods because they allow for more efficient and accurate mapping. This research applies digital mapping techniques and two terrestrially-based 3D visualization technologies, photogrammetry and Light Detection and Ranging (LiDAR), to the study of metamorphic terranes in the Panamint Mountains, California. This study reports on the spatial accuracy of TINs (triangulated irregular networks) generated from both photogrammetry and ground-based LiDAR using a terrestrial laser scanner (TLS) and discusses how spatial accuracy can be increased. Two levels of comparison were used to test spatial …

Evaluation Of Point Of Use Drinking Water Treatment Systems For Colonias In The Southwest United States, Isaac Campos Flores

Open Access Theses & Dissertations

Clean drinking water is often taken for granted in first world countries, such as the United States. However, thousands of colonias residents (settlements in the Southwest US that lack access to basic infrastructure) still lack access to clean drinking water. Such is the case in the Paso Del Norte Region. In Doña Ana County, NM, and El Paso County, TX, colonia residents typically rely on shallow domestic wells and hauled water, respectively. However, both water sources can pose health concerns from elevated total dissolved solids and microbiological contamination. With connection to centralized water treatment and distribution still years away, colonias …