Engineering Commons^™

Development Of Vs Profiles And Site Periods In The Mexico City Basin, Landon Joel Woodfield

Graduate Theses and Dissertations

This study presents dynamic site characterization measurements at 25 sites within the Mexico City Basin. The primary focus of the testing was along the western edge of the Mexico City Basin. At each site, active source Multi-channel Analysis of Surface Waves (MASW) arrays and passive source Microtremor Array Measurements (MAM) L-arrays and circular arrays were used to acquire dispersion data. Horizontal to Vertical Spectral Ratio (HVSR) data was collected to determine site periods at each location. These experimental dispersion data and site periods were fit using a joint inversion of Rayleigh and Love wave dispersion data and HVSR site period …

Numerically Modeling Steel Continuous Bridges For Early Age Concrete Deck Cracking, Abdul Aziz Nabil Salah

Graduate Theses and Dissertations

Early age bridge deck cracking is a common problem throughout the United States. Early age cracking develops shortly after the deck is poured. It reduces the serviceability and lifespan of bridges. Early age cracking can be typically attributed to either of two factors, 1) construction practices, and 2) shrinkage. The Arkansas Department of Transportation (ARDOT) has experienced early age bridge deck cracking. ARDOT currently specifies a sequence deck pour on most of their bridges; however, contractors prefer continuous deck pours because of ease and construction time. During the period of this TRC1903 research project, ARDOT has only approved a few …

Numerical Simulations Of Spread Foundations Supported On Stone Columns Using The Discrete Element Method, Anibal Enrique Santos Marin

Graduate Theses and Dissertations

The implementation of stone columns as a ground improvement technique has become more popular in geotechnical construction practice as a result of their ability to improve strength, stiffness and permeability characteristics of weak clayey soil deposits. There are several analytical and empirical approaches to estimate the bearing capacity of stone column foundation systems; however, there is notable variation in the performance of these existing methods when compared with full-scale experimental results. For very weak cohesive soils (i.e., undrained shear strength less than 15 kPa), the use of conventional stone columns becomes restricted because of the insufficient confinement that these types …

Best Practices For Asphalt Emulsion Particle Size Analyses Using A Coulter Counter, Logan P. Kiihnl

Graduate Theses and Dissertations

As asphalt pavements develop distresses, pavement preservation, maintenance, and rehabilitation treatments are used to mitigate distresses and extend the life of the pavement. Many of these treatments utilize asphalt emulsion. Previous research has linked particle size to material properties including viscosity and storage stability. General statements have also been made about particle size influencing emulsion performance while other researchers have identified a trend between particle size and prime coat penetration. Even though literature discusses the importance of particle size, there is little guidance on the best practices of asphalt emulsion particle size analyses, specifically with a Coulter counter.

Data collected …

Development Of Multi-Axial Fatigue Retrofits For Lock Gate Components, Logan Verkamp

Graduate Theses and Dissertations

Lock gates are essential infrastructure components to the United State (US) supply chain. They create large cost savings and environmental benefits when compared with traditional methods of transport (freight and rail). Because of the large quantity of goods and dependence on these shipping chains, the US economy can be drastically affected by an unexpected gate closure. Unfortunately, many lock gates within the US have reached or exceeded their designed life. Due to the intensity of cyclic loads and the environment, fatigue cracks have become a prominent issue. Developed cracks near the pintle region (a joint which the gate rotates and …

Using Robotics And Engineering Design Inquiries To Optimize Learning For Middle Level Teachers: A Case Study, Iman Chafik Chahine, Norman Robinson Iii, Kimbeni Mansion

Publications & Research

This exploratory case study reports findings on 20 middle-level science and mathematics teachers’ perceptions of the effectiveness of a one-year project in which teachers engaged in using robotics and engineering design inquiries in their classrooms. Principled by Bandura’s Social Learning Theory (SLT) and using mixed methods approaches, the study measured teachers' efficacy through the Mathematics Teaching Efficacy Belief Instrument (MTEBI) and observation logs before and after the program. The results of this study showed statistically significant differences between PRE MTEBI and POST MTEBI scores. Furthermore, five themes emerged that illuminated potential affordances and constraints that teachers perceive as opportunities and …

Prioritized Anomaly Catalog Generation Using Model-Based Reasoning, Jake Hedlund

Computer Science and Engineering Master's Theses

Anomaly management—the detection, diagnosis, and resolution of anomalies in a system—is traditionally performed using experiential techniques which are quickly computed, but poorly structured. Newer model-based approaches are more systematic and higher performing but are computationally expensive, which is a particular challenge for execution in an operational environment. This paper builds on a novel system to pre-compute model-based anomaly symptoms to enable quick retrieval and diagnosis in operational settings. New additions to this system include a simplified model interface, anomaly likelihoods associated with each component, and easier interpretation of results. The implemented system has been used successfully to detect and diagnose …

Multiscale Modeling And Simulation Of Clutter In Isar Imaging, Jon Mitchell

Electrical Engineering Dissertations - Archive

Clutter is common in applications of radar imaging and can adversely impact target imaging by contributing scattered energy that is not accounted for in target signal models. One potential source of clutter is moving foliage in the vicinity of the target, such as a target embedded in a forest. ISAR imaging of moving clutter results in an equivalent current image that changes over each imaging sample. The stochastic nature of this clutter equivalent current presents challenges in detecting and imaging a weak embedded target using traditional algorithms. This dissertation proposes a multiscale model and analysis method to characterize the multiscale …

Distributed Optimal Policies For Multi-Agent Systems Under Uncertainties, Mushuang Liu

Electrical Engineering Dissertations - Archive

Multi-agent systems (MAS) have attracted increasing attention in the past years due to their wide applications in mobile robots, sensor networks, autonomous driving systems, etc. Along with this trend, developing distributed optimal policies for MAS under uncertainties has become indispensable. Multi-dimensional uncertainties often modulate system dynamics in a complicated fashion, which leads to computational challenges for real-time control. In many practical MAS, each agent also has its own interest to optimize beyond a global objective. Developing distributed optimal control for agents with self-interests is needed. To address the above challenges, this dissertation contributes in two major directions for MAS: 1) …

Plasma Electrolytic Oxidation Of Titanium Under Constant Applied Voltage, Joshua Paul Twaddle

Material Science and Engineering Theses - Archive

Plasma Electrolytic Oxidation (PEO) is a method capable of applying nonmetallic coatings to metallic substrates submerged in electrolyte via a plasma development under high voltage. The PEO technique is particularly useful in the coating of materials such as Ti-, Al-, and Mg-based alloys. In this study, the effects of varying processing voltage and time on oxide coating characteristics formed on pure titanium surfaces was investigated. First, it was necessary to prove that the selected electrolyte type and concentration could produce PEO coatings in a predictable fashion. Experiments were performed with constant current density by constantly controlling the voltage, so the …

Heat Transfer Measurements And Enhancement For Materials And Processes In Polymer Extrusion Based Additive Manufacturing, Hardikkumar Mangaldas Prajapati

Mechanical and Aerospace Engineering Dissertations - Archive

Additive manufacturing (AM) is a burgeoning method for manufacturing over the subtractive manufacturing methodologies. Among the various method of polymer additive manufacturing the fused deposition modeling (FDM) also known as 3D printing is the most popular technique. In this technique, a rastering extruder dispenses a thermoplastic material on to a bed at a temperature greater than its glass transition temperature to build the part. Due to the additive nature of the process, AM introduces several challenges related to functional properties such as strength, thermal conductivity, etc of the eventual part. Measurement of thermal conductivity of additively manufactured polymer samples in …

Reinitiation Mode Study Of Highly Irregular Detonation, Nandakumar Vijayakumar

Mechanical and Aerospace Engineering Dissertations - Archive

The propagation of detonation waves is governed by their stability characteristics. Interest in highly unstable detonation grew when early experiments revealed limits of operation to be directly proportional to the stability of detonation. This research focuses on reinitiation pathways of highly irregular self-sustaining detonation. This is an important aspect of stability which is not yet fully understood, while many possible mechanisms have been proposed in the literature. First, a one-dimensional instability model simulation was performed using a global one-step chemistry mechanism to understand the different unstable modes by increasing the activation energy of a mixture of hydrogen and oxygen. The …

Measurement And Optimization Of Thermal Transport Phenomena For Weld Strength Improvement In Polymer Extrusion Based Additive Manufacturing, Darshan Babu Ravoori

Mechanical and Aerospace Engineering Dissertations - Archive

Additive manufacturing (AM) processes involve layer-by-layer addition of material to fabricate a 3-dimensional part. AM offers significant design and manufacturing flexibility compared to traditional manufacturing approaches. The major challenge in polymer-based additive manufacturing (AM) is that printed parts often have poor thermal/structural properties. These properties depend on weld strength of filaments and which intern depends on the degree of healing/neck growth between deposited polymers. The major contribution of this dissertation is understanding the importance of heat transfer during the printing process on the polymer neck growth and presented with techniques to improve the thermal and structural strength of finished part. …

Design And Optimization Of Thermal Management Approaches In Data Center Applications, Rajesh Kasukurthy

Mechanical and Aerospace Engineering Dissertations - Archive

In the present day to day life, Internet of Things (IOT) is everything, i.e., Internet and telecommunication is needed for almost every task of our life, which require data centers. These data centers provide various facilities such as, data processing, storage, transmission, maintenance, operations etc., To perform these tasks, a huge amount of power is consumed, which in turn generates large amount of heat. As these data centers are to be made operational throughout the year, cooling of data centers is of utmost importance. The continued increase in heat flux at the chip level due to new and robust technology …

Computational Study Of Air-Cooled Servers With Improved Ducting And Chassis Re-Design, Himanshu Girishchandra Modi

Mechanical and Aerospace Engineering Theses - Archive

In recent years there has been a phenomenal increase in cloud computing, net-working, virtualization, and storage which has led to an increase in demand for data centers. To meet this demand, there is a need for the latest computing nodes which causes an increase in power consumption. The cooling system occupy almost 40% portion of total energy consumption. Per ASHRAE TC 9.9, IT equipment needs to operate within recommended and allowable temperatures and humidity zone based on the circumstances. As the inlet air temperature increases, fan power consumption increases too and the Central Processing Units (CPUs) and high heat-generating components …

Experimental Study Of Dynamic Cooling Of Racks Using Flow Control Devices, Fnu Akash

Mechanical and Aerospace Engineering Theses - Archive

A data center is a cluster of multiple servers that a company uses to store and process large amounts of data. Due to never-ending demands, the processor densities are increasing every day. A higher processor density would result in the servers heating up more than it would normally creating a need for an efficient cooling system. On an average a water-cooled system would consume up to 40% of the total power required by a data center. Studies are being conducted on improving the overall efficiency of the system by either improving the thermal properties of the system or by improving …

Modeling, Fabrication, And Characterization Of Porous Inconel 718 Structures Using Selective Laser Melting Process, Srihari Srivathsan

Mechanical and Aerospace Engineering Theses - Archive

Bio-inspired cellular structures are of great interest these days for many applications, from engineering research to industries. Honeycomb, Body-Centered Cubic with/without Z-struts (BCC-Z/ BCC), Face Centered Cubic with/without Z-struts (FCC-Z/ FCC), and Triply Periodic Minimal Surface (TPMS) such as Gyroid, Diamond, and Schwartz lattices are the most common bio-inspired lattice structures. These structures can be tailored based on their structural organization resulting in superior materials with lightweight properties, adequate strength, and low stiffness. Thankfully, additive manufacturing (AM) has made the fabrication of these complex cellular materials realistic. However, the use of AM could lead to several defects, such as damaged …

Cfd Analysis On Liquid Cooled Cold Plate Using Copper Nanoparticles, Sarthak Agarwal

Mechanical and Aerospace Engineering Theses - Archive

In today’s world, most data centres have multiple racks with numerous servers in each of them. The high amount of heat dissipation has become the largest server-level cooling problem for the data centres. The higher dissipation required, the higher is the total energy required to run the data centre. Although still the most widely used cooling methodology, air cooling has reached its cooling capabilities especially for High-Performance Computing data centres. Liquid-cooled servers have several advantages over their air-cooled counterparts, primarily of which are high thermal mass, lower maintenance and eventually lower costs by maintenance by labour. Nano-fluids have been used …

Prediction And Validation Of Continuous Fiber Stiffened Plates Manufactured With Continuous Fiber Fabrication, Nabeel Ahmed Khan

Mechanical and Aerospace Engineering Theses - Archive

The purpose of this thesis was to develop an analytical method for predicting the structural properties of continuous fiber stiffened plates, which was then validated both experimentally and via finite element analysis. The MarkForged Mark Two 3D printer enables parts to be printed with continuous carbon fibers embedded within them. A manufacturing process was developed for printing stiffened grids with our without skins, with continuous fiber reinforcement on the top and bottom of the stiffening ribs, which allows bending stiffness can be maximized. An orthotropic grid was printed using Continues Filament Fabrication (CFF), an additive manufacturing process that embeds reinforcing …

Stirred Suspension Bioreactor Differentiation Of Human Mesenchymal Stem Cells Into Smooth Muscle Cells, Chris Slavin

Biomedical Engineering Undergraduate Honors Theses

Human mesenchymal stem cells (hMSCs) are a promising candidate for cellular therapies due to their multipotency, self-renewal capacity, and immunomodulatory properties. However, their isolation is a difficult and potentially painful process with very low yield, and traditional static mammalian cell culture techniques are too slow and expensive for large scale growth and differentiation of stem cells to be practical. Current research is focused on improving methods for cultivating hMSCs in stirred suspension bioreactors (SSBs), but little work has been done with regard to their differentiation in dynamic conditions such as those in SSBs. Differentiation at a large scale would increase …

The Response Of Astrocytes To Mechanical Stimuli, Courtney Bahan

Biomedical Engineering Undergraduate Honors Theses

Traumatic brain injuries are a common cause of injury and result from a blow to the head whether it be blunt, penetrating, or inertial. TBIs are typically obtained in a fall, while playing a sport, or in a car crash. TBIs can be diagnosed as mild (commonly referred to as a concussion), moderate, or severe based upon their score from the Glasgow coma scale. TBIs can also lead to other risks such as epilepsy or Alzheimer’s Disease as well as increasing the risk of suffering another TBI. Astrocytes are heterogeneous glial cells in the brain that alter their response based …

Photobiomodulation And Stem Cell Differentiation: Application To Modulate Adipogenesis Through Cellular And Nuclear Morphology, Andrew Redmond Mccolloch

Bioengineering Dissertations - Archive

Mesenchymal stem cells (MSCs) are of great interest in regenerative medicine due to their capability to self-renew and differentiate to various lineages. Typically, differentiation to specific cell types has relied on the use of growth factors and other reagents to provide an environment conducive to the desired cell type. More recently, orthogonal cues other than chemical factors have been elucidated to regulate the lineage commitment. For example, the cell shape, cellular mechanics and substrate stiffness have been found to play a role in determining the fate of MSCs. However, it remains still elusive how the morphological and mechanical changes in …

Study Of Upregulation Of Drug Resistance In H460 Lung Cancer Cells Via Microchannel Device, Nowmi Haider

Bioengineering Theses - Archive

Metastasis is the main reason of high mortality rates in cancer patients. Treating these patients becomes difficult once the cancer has metastasized, especially due to their drug resistance. Drug resistance is a common problem that occurs when treating cancer patients, as in most cancer types, the cells are capable of drug efflux. This makes treatments like chemotherapy ineffective. Therefore, it is important to find alternative methods of treatment that can effectively kill drug resistant cancer cells. Lung cancer is one type of cancer that is the second most diagnosed cancer in the U.S. In this study, microchannels were used to …

Experimental And 3d Finite Element Analyses Of Invert-Removed Circular Corrugated Metal Pipe Culverts Renewed With Polymer Spray-Applied Pipe Lining, Samrat Raut

Civil Engineering Theses - Archive

Corrugated metal pipes (CMPs) are one of the widely used culvert structures in the American highway system. Compared to other types of culverts, CMPs have shorter design life, and many CMP culverts have reached or exceeded their design life. Therefore, renewal or replacement of those CMPs is needed to ensure the safety and service of the highways. Since replacements of these culverts are costly, renewalis less costly and has been on the focus in this decade. Different rehabilitation methods have been proposed by different DOTs and the researchers from open-cut methods to trenchless technology. Since open-cut methods disturb the operation …

Flexural Load Capacity Of Heat-Treated Concrete Mixed With Recycled Glass Aggregate And Glass Pozzolan, Enrique Gonzalez Tapia

Civil Engineering Theses - Archive

This research focuses on determining the effects of adding glass aggregate and glass pozzolan to concrete that has been exposed to high temperatures. Previous work, based on finding the recommended proportions of recycled components for optimum results, was done to analyze the effects of adding recycled glass components to concrete. Based on those studies, a replacement ratio of 30% glass aggregates and 20% glass pozzolan was used in this project. The compressive strength of concrete has been extensively studied and has been shown to increase in strength when glass components are used in their correct proportions. Less research has been …

Experimental Study Of Flexural Behavior Of Preflex Sfrc-Encased Steel Joist Composite Beams, Niraj Narendra Bankatlal Bora

Civil Engineering Theses - Archive

This study investigates the behavior of encased steel composite beams in straight and preflex beams, constructed and tested at Civil Engineering Laboratory Building (CELB). Upwards camber is provided in the steel sections in steel angles and HSS tube in the composite beam encased in Steel fibers reinforced concrete (SFRC). Experimental procedure has been performed to study the flexural behavior of composite steel joists encased in SFRC. Compressive strength, tensile strength and modulus of rupture are computed. The physical properties of steel fiber reinforced concrete are calculated through testing at the UTA Civil Engineering Laboratory Building. Eighteen cylindrical (4”x8”) specimens, eighteen …

Experimental And Numerical Study Of Process Parameters Effects Towards Part Quality And Porosity During Powder Bed Additive Manufacturing Processes., Subin Shrestha

Electronic Theses and Dissertations

Powder bed additive manufacturing (PB-AM) process utilizes an electron beam or a laser as a heat source to melt the metallic powder particles. These processes have the capability of freeform fabrication, however certain defects such as porosity, high surface roughness, etc. would hinder its application. It is important to understand the effect of the process parameters and the underlying physical phenomena, which lead to the formation of such defects. In this regard, a three-dimensional (3D) thermo-fluid model is developed to study the effect of beam speed on the surface morphology during powder bed electron beam additive fabrication (PB-EBAF). Besides, the …

Medusa: A Low-Cost, 16-Channel Neuromodulation Platform With Arbitrary Waveform Generation, Fnu Tala, Benjamin C. Johnson

Electrical and Computer Engineering Faculty Publications and Presentations

Neural stimulation systems are used to modulate electrically excitable tissue to interrogate neural circuit function or provide therapeutic benefit. Conventional stimulation systems are expensive and limited in functionality to standard stimulation waveforms, and they are bad for high frequency stimulation. We present MEDUSA, a system that enables new research applications that can leverage multi-channel, arbitrary stimulation waveforms. MEDUSA is low cost and uses commercially available components for widespread adoption. MEDUSA is comprised of a PC interface, an FPGA for precise timing control, and eight bipolar current sources that can each address up to 16 electrodes. The current sources have a …

Comparison Of Mpi And Spark For Data Science Applications, Manvi Saxena, Shweta Jha, Saba Khan, John Rodgers, Peggy Lindner, Edgar Gabriel

Engineering Management and Systems Engineering Faculty Research & Creative Works

Data Science applications represent a growing fraction of the scientific computing workload, many of them written in Python. The goal of this paper is to compare two popular parallel programming models, namely MPI and Apache Spark for Python based Data Science applications. The paper presents communication and file I/O microbenchmarks to evaluate the MPI support for Python applications and uses two applications use-cases from Natural Language Processing to compare the performance of the MPI and the Spark versions. Our results indicate that the MPI version shows better scalability and performance than the PySpark version of the code. On the other …

The Development Of On-Chip Optofluidic Droplet Lasers, Han Zhang

Electrical Engineering Dissertations - Archive

Optofluidic lasers have been an emerging field for the applications of biological sensing and diagnosis, chemical sensing, and point-of-care devices. Droplets, as optical cavities, confines whispering gallery modes with high quality factors in small volumes. Optofluidic droplet lasers have brought the droplet-based microfluidics and droplets as micro-resonators to one platform, showing potentials on applications in highly sensitive bio/chemical detection, tunable lasers, cell tracking and tissue imaging. Until now, optofluidic droplet lasers can be categorized into two types, static droplet lasers and droplet lasers on the flow. Static droplet lasers offer long lifetime for biosensing, while droplet lasers on the flow …