Engineering Commons^™

Horizontal Diversity In Test Generation For High Fault Coverage, Arbab Alamgir, Abu Khari Bin A'Ain, Norlina Paraman, Usman Ullah Sheikh, Ian Grout

Turkish Journal of Electrical Engineering and Computer Sciences

Determination of the most appropriate test set is critical for high fault coverage in testing of digital integrated circuits. Among black-box approaches, random testing is popular due to its simplicity and cost effectiveness. An extension to random testing is antirandom that improves fault detection by maximizing the distance of every subsequent test pattern from the set of previously applied test patterns. Antirandom testing uses total Hamming distance and total cartesian distance as distance metrics to maximize diversity in the testing sequence. However, the algorithm for the antirandom test set generation has two major issues. Firstly, there is no selection criteria …

Reconstructing Insect Pursuit Flight Kinematics In The Wild, Haribabu Boddeeti

Graduate Research Theses & Dissertations

With their agile maneuvers and aerodynamic feats, flying insects continue to inspire the design, sensing, and control of unmanned aerial vehicles. Among the different behaviors that such insects perform, the mating pursuit stands out in terms of the high speeds and quick turns that each insect performs during the chase. Despite their frequent occurrence in nature, pursuit events between mating insects are rarely analyzed. This is because mating events are difficult to film in the wild or elicit in laboratory settings. The long-term goal of this research is to quantify the kinematics of flying insects in pursuit. The specific objective …

Fundamental Studies Of Chemical Stability And Carrier Process In Hybrid Perovskite Materials, Jue Gong

Graduate Research Theses & Dissertations

This dissertation comprehensively studies the optoelectronic properties of organic-inorganic hybrid perovskites to fundamentally answer their foundations of outstanding performance on solar cells, photodetectors, nanowire lasers and other optoelectronic applications. Specifically, a novel type of charge carrier-lattice interaction was discovered in perovskite methylammonium lead iodide (CH3NH3PbI3), where photoluminescence lifetime of photoinduced carriers is strongly dependent on the rotational frequency of CH3NH3+, as modulated via substitution of hydrogens with deuterium atoms in the organic cation. In addition, two-dimensional Ruddlesden-Popper perovskite (CH3NH3)2Pb(SeCN)2I2 was first synthesized and characterized in the field, and its photoluminescence properties were systematically examined. The existence of intensive photoluminescence peak …

Investigating The Effects Of Orientation Control Of Graphene Nanoplatelet Suspensions By A Magnetic Field On The Viscosity Of A Nanofluid System, Radhika Iyer

Graduate Research Theses & Dissertations

In this investigation, the rheological behavior of paraffin oil containing diamagnetic suspensions is characterized under varying magnetic field conditions. The particles suspended in the white paraffin oil at mass concentrations of 0.1, 0.3, 0.5, 0.7 and 1% m/m are two-dimensional graphene nanoplatelets with an average thickness of 2 – 8 nm. Rheological experiments were conducted using a Brookfield DV2T viscometer with a modified cylindrical spindle over the range of shear rates between 192 s-1 to 1928 s-1. A Neodymium N42 ring magnet with a surface strength of 1.32 T generated the magnetic field conditions for the rheological experiments and was …

Driving Under Weather: An Exploration Of The Traveling Salesman Problem With Probabilistic Unfavorable Driving Conditions, Andrew Wright

Graduate Research Theses & Dissertations

Inclement weather has a visceral impact on transportation systems, but it has been made undeniably clear. Reliable ground transportation is absolutely fundamental in global logistics, and the need to deliver goods to customers in a timely manner has never been more important. The field of operations research offers some quality logistics problems with the foresight to provide efficient transportation solutions. One of the most prevalent problems in operations research is the Traveling Salesman Problem (TSP). Although much research has gone into solving the classic TSP and some of its variants, none have been truly dedicated to integrating meteorological sciences.

The …

Development Of A Multi-Robot Testbed For Direct Human-Swarm Interaction, Venkata Satya Kiran Maridi

Graduate Research Theses & Dissertations

Robotic swarms are well suited for missions that involve covering large areas such as environmental monitoring, search-and-rescue operations, as well as those that require fusing information from multiple sources such as target tracking and machine inspection. However, navigating a swarm of robots effectively requires performing higher-level functions that are typically executed by humans such as commanding them to stay close and guiding them along with a preplanned route. In this context, the ability of multiple robots to stay together autonomously significantly reduces the cognitive load on a human operator. The goal of this thesis is to design and build a …

Theoretical Study Of Laser-Assisted Machining On Silicon Nitride Hollow Ceramic Cylinder Using Finite Element Method, Mudassar Hussain Ansari Mohammed

Graduate Research Theses & Dissertations

The most commonly used technique for machining ceramics is diamond grinding. It accounts for up to 75% of the manufacturing costs resulting in high cost of the product. An LED bulb offering increased brightness, energy saving and long life by using ceramic integration to LED chips costs around 10 times to a normal LED bulb. Complex geometries used in electronics, medical surgeries, aerospace, and automobile industries require the use of costly molds or powder metallurgy for low batch production which does not justify the cost. Laser Assisted Machining (LAM) is a process that uses a laser to locally heat the …

Biomechanical Exposures Of Neck And Shoulder In Virtual Reality, Sai Akhil Penumudi

Graduate Research Theses & Dissertations

Virtual Environment pose certain potential postural discomfort or pain of the neck and shoulder that could be different from a real environment. There has been a lack of ergonomic guidelines for the Virtual Reality (VR) usage with the hand gesture interaction. The purpose of this study was to evaluate the effect of the vertical target locations on biomechanical exposures of the neck and shoulder and task performance during VR interactions. Twenty subjects performed standardized pointing and painting tasks with five different target locations (15° upward, neutral, 15° downward, 30° downward, and self-selected). Users’ postures, gravitational moments, muscle activities of the …

Implementation Of Systems-Level Learning In A Community College Mechatronics Program, Margie N. Porter

Graduate Research Theses & Dissertations

This is a qualitative case study of the complete implementation of systems-level learning (SLL) pedagogy throughout a mechatronics engineering department in a community college in the United States. SLL was developed from the German engineering apprenticeship model, resulting in engineering graduates with what our German counterparts call Handlungskompetenz. Graduates of these programs have the flexibility to quickly adapt to new engineering systems and situations in a self-directed way without months of on-the-job training. This skill is related to adaptive expertise and is not the type of skill traditionally taught to engineering students.

Chronological and descriptive analyses were performed on semi-structured …

Evaluating The Role Of Energy Demand Prediction And Renewable Energy Utilization On Energy Dependency Management: A Generic System Dynamics Model, Emad Rabiei Hosseinabad

Graduate Research Theses & Dissertations

Supplying energy has become one of the biggest concerns of developed countries due to the growing energy needs in the last decades. Security of energy supply has forced countries to rely more on energy imports from external sources, and become energy dependent to a greater extent. Utilizing available renewable energy resources has been characterized as a reliable indicator to mitigate energy dependency in countries as well as securing the supplying of energy-based needs in the future. This research explores the impact of renewable energies as trustful resources in mitigating energy imports form external sources with investigation of its viability with …

Surface Engineering And Monomer Design For Light-Mediated Ring Opening Metathesis Polymerization, Ishan A. Fursule

Theses and Dissertations--Chemical and Materials Engineering

Stimuli-responsive materials are changing the landscape of actuated materials, optoelectronics, molecular machines, solar cells, temporary memory storage, and biomedical materials. Specifically, photo-responsive polymers have gained acceleration in research and application since the last two decades in the form of a surface coating and micro-patterns. Light as a stimulus can be coherent, mono or polychromatic, tunable for power (intensity) and energy (wavelength), and has precise spatiotemporal control. Conventional surface coating techniques such as spin coating are unable to impart properties to the coatings in terms of sturdiness, homogeneity, uniformity over the complex surface, post deposition modification, and process efficiency. Also, in …

Understanding Carbohydrate Recognition Mechanisms In Non-Catalytic Proteins Through Molecular Simulations, Abhishek A. Kognole

Theses and Dissertations--Chemical and Materials Engineering

Non-catalytic protein-carbohydrate interactions are an essential element of various biological events. This dissertation presents the work on understanding carbohydrate recognition mechanisms and their physical significance in two groups of non-catalytic proteins, also called lectins, which play key roles in major applications such as cellulosic biofuel production and drug delivery pathways. A computational approach using molecular modeling, molecular dynamic simulations and free energy calculations was used to study molecular-level protein-carbohydrate and protein-protein interactions. Various microorganisms like bacteria and fungi secret multi-modular enzymes to deconstruct cellulosic biomass into fermentable sugars. The carbohydrate binding modules (CBM) are non-catalytic domains of such enzymes that …

Application Of Process Systems Engineering Tools And Methods To Fermentation-Based Biorefineries, Kwabena Darkwah

Theses and Dissertations--Chemical and Materials Engineering

Biofuels produced from lignocellulosic biomass via the fermentation platform are sustainable energy alternatives to fossil fuels. Process Systems Engineering (PSE) uses computer-based tools and methods to design, simulate and optimize processes. Application of PSE tools to the design of economic biorefinery processes requires the development of simulation approaches that can be integrated with existing, mature PSE tools used to optimize traditional refineries, such as Aspen Plus. Current unit operation models lack the ability to describe unsteady state fermentation processes, link unsteady state fermentation with in situ separations, and optimize these processes for competing factors (e.g., yield and productivity). This work …

Design And Analysis Of Curcumin Conjugated Poly(Beta-Amino Ester) Networks For Controlled Release In Oxidative Stress Environments, Carolyn T. Jordan

Theses and Dissertations--Chemical and Materials Engineering

Oxidative stress, the imbalance of free radical generation with antioxidant defenses, leads to cellular inflammation, apoptosis and cell death. This compromised environment results in debilitating diseases, such as oral mucositis (OM), atherosclerosis, and ischemia/reperfusion injury. Antioxidant therapeutics has been a proposed strategy to ameliorate these imbalances and maintain homeostatic environments. However, the success of these approaches, specifically curcumin, has been limited due to characteristics such as hydrophobicity and high reactivity when released as bolus doses to contest to oxidative stress induced diseases. The development of a controlled release system to aid in protection of the antioxidant capacity of curcumin, as …

The Development Of Microfluidic Devices For The Production Of Safe And Effective Non-Viral Gene Delivery Vectors, Jason Matthew Absher

Theses and Dissertations--Chemical and Materials Engineering

Including inherited genetic diseases, like lipoprotein lipase deficiency, and acquired diseases, such as cancer and HIV, gene therapy has the potential to treat or cure afflicted people by driving an affected cell to produce a therapeutic protein. Using primarily viral vectors, gene therapies are involved in a number of ongoing clinical trials and have already been approved by multiple international regulatory drug administrations for several diseases. However, viral vectors suffer from serious disadvantages including poor transduction of many cell types, immunogenicity, direct tissue toxicity and lack of targetability. Non-viral polymeric gene delivery vectors (polyplexes) provide an alternative solution but are …

Combinatorial Screening Approach In Developing Non-Equiatomic High Entropy Alloys, Azin Akbari

Theses and Dissertations--Chemical and Materials Engineering

High entropy alloys (HEA) are a relatively new group of alloys first introduced in 2004. They usually contain 5 to 6 different principle elements. Each of these elements comprise 5-35 at. % of the chemical composition of the alloy. There is a growing interest in the research community about the development of these alloys as well as their engineering applications. Some HEAs have interesting properties that have made them well suited for higher temperature applications, particularly refractory uses, while some have been shown to maintain their mechanical properties even at cryogenic temperatures.

Initially, the HEA research was focused on developing …

A Microstructure-Based Model Validated Experimentally For Quantification Of Short Fatigue Crack Growth In Three-Dimensions, Pei Cai

Theses and Dissertations--Chemical and Materials Engineering

Built on the recent successes in understanding the crystallographic mechanism for short fatigue crack (SFC) growth across a grain boundary (GB) and developing an experimental method to quantify the GB resistance against short crack growth, a microstructure-based model was developed in this study to simulate the growth behaviors of SFCs in 3-D, by taking into account both the driving force and resistance along at each point along the crack front in an alloy. It was found that the GB resistance was a Weibull function of the minimum twist angle of crack deflection at the boundary in AA2024-T3 Al alloys. In …

Defect Chemistry And Transport Properties Of Solid State Materials For Energy Storage Applications, Xiaowen Zhan

Theses and Dissertations--Chemical and Materials Engineering

Replacing organic liquid electrolytes with nonflammable solid electrolytes can improve safety, offer higher volumetric and gravimetric energy densities, and lower the cost of lithium-ion batteries. However, today’s all-solid-state batteries suffer from low Li-ion conductivity in the electrolyte, slow Li-ion transport across the electrolyte/electrode interface, and slow solid-state Li-ion diffusion within the electrode. Defect chemistry is critical to understanding ionic conductivity and predicting the charge transport through heterogeneous solid interfaces. The goal of this dissertation is to analyze and improve solid state materials for energy storage applications by understanding their defect structure and transport properties.

I have investigated defect chemistry of …

Mixed Matrix Flat Sheet And Hollow Fiber Membranes For Gas Separation Applications, Nicholas W. Linck

Theses and Dissertations--Chemical and Materials Engineering

Mixed matrix membranes (MMM) offer one potential path toward exceeding the Robeson upper bound of selectivity versus permeability for gas separation performance while maintaining the benefits of solution processing. Many inorganic materials, such as zeolites, metal-organic frameworks, or carbon nanotubes, can function as molecular sieves, but as stand-alone membranes are brittle and difficult to manufacture. Incorporating them into a more robust polymeric membrane matrix has the potential to mitigate this issue.

In this work, phase inversion polymer solution processing for the fabrication and testing of asymmetric flat sheet mixed matrix membranes was employed with CVD-derived multiwall carbon nanotubes (MWCNTs) dispersed …

The Formation Mechanism Of Α-Phase Dispersoids And Quantification Of Fatigue Crack Initiation By Experiments And Theoretical Modeling In Modified Aa6061 (Al-Mg-Si-Cu) Alloys, Gongwang Zhang

Theses and Dissertations--Chemical and Materials Engineering

AA6061 Al alloys modified with addition of Mn, Cr and Cu were homogenized at temperatures between 350 ^ºC and 550 ^ºC after casting. STEM experiments revealed that the formation of α-Al(MnFeCr)Si dispersoids during homogenization were strongly affected by various factors such as heating rate, concentration of Mn, low temperature pre-nucleation treatment and homogenization temperature. Through analysis of the STEM results using an image software Image-Pro, the size distributions and number densities of the dispersoids formed during different annealing treatments were quantitatively measured. It was revealed that increasing the heating rate or homogenization temperature led to a reduction of …

Synthesis And Characterization Of Magnesium - Titanium Composites By Severe Plastic Deformation, Baleegh Alobaid

Theses and Dissertations--Chemical and Materials Engineering

Magnesium alloys are widely used in engineering applications, including aerospace and automobile industries, due to their desirable properties, such as lower density, high damping capacity, relatively high thermal conductivity, good machinability, and recyclability. Researchers have, therefore, been developing new magnesium materials. However, mechanical and corrosion properties are still limiting many commercial applications of magnesium alloys. In this Ph.D. thesis research, I developed Mg-Ti composite materials to offer some solutions to further improve the mechanical behavior of magnesium, such as titanium-magnesium (Ti-Mg) claddings, Mg-Ti multilayers, and Ti particle enforced Mg alloys. Low cost manufacturing processes, such as hot roll-bonding (RB) and …

Synthesis Of Biologically-Inspired Nanofiltration Membranes Using Protected, Mutated, And Simulated Aquaporins, Priyesh Ashokrao Wagh

Theses and Dissertations--Chemical and Materials Engineering

Gram-negative bacterial cells are surrounded by a cell membrane which protects the cell and controls the transport of nutrients and waste products in and out of the cells at a fast rate. This rapid transport of nutrients and wastes through the cell membrane is made possible by channel proteins called porins. Various types of porins present in the cell membrane have specific functions depending on their selectivity towards different nutrients, and channel proteins selective towards water are called aquaporins. These proteins restrict the passage of all entities except water molecules and they provide a fast transport rate of water molecules …

Surface Functionalization Via Photoinitiated Radical Polymerization For Rare Cell Isolation And Mechanical Protection, Calvin Frank Cahall

Theses and Dissertations--Chemical and Materials Engineering

Surface functionalization of living cells for cell therapeutics has gained substantial momentum in the last two decades. From encapsulating islets of Langerhans, to cell laden gels for tissue scaffolds, to individual cell encapsulation in thin hydrogels, to surface adhesives and inert surface camouflage, modification of living cell surfaces has a wide array of important applications. Here we use hydrogel encapsulation of individual cells as a mode of protection from mechanical forces for high throughput cell printing, and chemical stimuli for the isolation of rare cells in blood.

In the first study, we review methods of surface functionalization and establish a …

The Physical Behavior And Characterization Of Nanoporous Silicon And Dispenser Cathode Surfaces, Tyler Lucius Corey Maxwell

Theses and Dissertations--Chemical and Materials Engineering

Nanostructured materials have received a surge of interest in recent years since it has become apparent that reducing the size of a material often leads to heightened mechanical behavior. From a fundamental standpoint, this stems from the confinement of dislocations. Applications in microelectromechanical devices, lithium ion batteries, gas sensing and catalysis are realized by combining the improvements in mechanical behavior from material size reduction with the heightened chemical activity offered by materials with a high surface-area-to-volume ratio. In this study, films of nanoporous Si-Mg were produced through magnetron sputtering, followed by dealloying using an environmentally benign process with distilled water. …

Biomechanical Evaluation Of Friction-Reducing Devices For Transferring Patients, Veera Aneesh Kuppam

Graduate Research Theses & Dissertations

Professional caregivers and nurses are prone to a greater risk of work-related musculoskeletal disorders, which is primarily related to manual patient handling. In common various transfer devices are used to transfer patients, the efficacy of friction-reducing devices in reducing biomechanical stress in the low back and upper extremities has not been systematically evaluated. Twenty professional caregivers performed standardized lateral pulling, pushing and sliding up tasks with selected transfer devices (draw sheet, slide sheet, slide board, and air-assisted transfer device). Caregivers’ hand-pull force, shoulder, and trunk posture, shoulder moment, muscle activity in wrist flexor, wrist extensor, biceps, triceps, trapezius, and erector …

Minimizing Total Number Of Tardy Jobs In Two-Stage Flow Shop Using Simulated Annealing And Column Generation, Shashwot Uprety

Graduate Research Theses & Dissertations

This research considers a scheduling problem where jobs need to be grouped in batches and scheduled in a two-stage flow shop with batch processing machines. The jobs are batched in such a way that machine capacity is not violated. The batches are scheduled in such a way to reduce the total number of tardy jobs. The problem under study, denoted as F2 | Batch | ΣUi in scheduling literature, has received less attention. The problem under study is NP-hard. Consequently, commercial solvers used to solve mathematical formulations to find an optimal solution require prohibitively long run times.

In this thesis, …

Morphological And Energetic Effects On Charge Transport In Conjugated Polymers And Polymer-Nanowire Composites, Zhiming Liang

Theses and Dissertations--Chemistry

Organic semiconductors have wide applications in organic-based light-emitting diodes, field-effect transistors, and thermoelectrics due to the easily modified electrical and optical properties, excellent mechanical flexibility, and solution processability. To fabricate high performance devices, it is important to understand charge transport mechanisms, which are mainly affected by material energetics and material morphology. Currently it is difficult to control the charge transport properties of new organic semiconductors and organic-inorganic nanocomposites due to our incomplete understanding of the large number of influential variables. Molecular doping of π-conjugated polymers and surface modification of nanowires are two means through which charge transport can be manipulated. …

Comparative Study Of Cv3 Carbonaceous Chondrites Allende And Bali Using Micro-Raman Spectroscopy And Sem/Eds, Raka Paul

All Graduate Theses, Dissertations, and Other Capstone Projects

The birth of the solar system (over 4 billion years) is speculated to have happened from a nebula, swirling and compacting in localized regions to eventually form the Sun and planets. This complex process consists of numerous changes and intermediary steps, yet to be fully understood. Carbonaceous chondritic meteorites are relics of that process and therefore have potential to reveal information about the formation history. Several theories have been formulated linking their composition to planet formation. This study focusses on two carbonaceous chondritic specimens, Allende and Bali, both of the group CV and petrologic type 3. CV meteorites are abundant …

Preventing Osteoarthritis By Targeting The Transforming Growth Factor Beta Signaling Pathway, Robert Dalton Chavez

All ETDs from UAB

Osteoarthritis (OA) is characterized by degenerated cartilage. In age-related OA, the molecular mechanisms that initiate cartilage erosion are not well defined. However, transforming growth factor beta (TGF-β) signaling is attenuated in the cartilage of patients with age-related OA and therefore may play a role in the disease. Degenerated cartilage has a rough surface and exhibits changes in stiffness. Proteoglycan 4 (PRG4), also known as lubricin, helps lubricate the surface of cartilage, and 3’-phosphoadenosine 5’-phosphosulfate synthase 2 (PAPSS2) helps maintain the stiffness of cartilage. Both PRG4 and PAPSS2 are regulated by TGF-β and down-regulated in OA cartilage. The present research elucidated …

Impact Of Mortgage Characteristics On Retail Mortgage Transaction Completion Time, Kareem Atalla Tannous

Walden Dissertations and Doctoral Studies

In the mortgage industry, many mortgage lenders cannot manage mortgage workflow systems while meeting and exceeding organizational objectives. Organizations with an above-industry average turnaround time (ATT) to complete a retail mortgage transaction (RMT) from origination to funding experience revenue losses. Grounded in the proposition that mortgage loan purpose (MLP), mortgage loan type (MLT), and subject property type (SPT) impact ATT to complete an RMT, the purpose of this causal-comparative study was to assess the impact of MLP, MLT, and SPT on ATT to complete an RMT. Using archival data records (N = 146) from a selected mortgage institution in the …