Engineering Commons^™

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 …

Peer To Peer Digital Rights Management Using Blockchain, James Rinaldi

University of the Pacific Theses and Dissertations

Content distribution networks deliver content like videos, apps, and music to users through servers deployed in multiple datacenters to increase availability and delivery speed of content. The motivation of this work is to create a content distribution network that maintains a consumer’s rights and access to works they have purchased indefinitely. If a user purchases content from a traditional content distribution network, they lose access to the content when the service is no longer available. The system uses a peer to peer network for content distribution along with a blockchain for digital rights management. This combination may give users indefinite …

Evaluation Of The Rotr 1: An Innovative Device To Reactively Strengthen The Shoulder, Bradley Tomio Yet Kong Hirayama

University of the Pacific Theses and Dissertations

This study assesses the effectiveness of an innovative shoulder training and rehabilitation device, the Rotr 1. The device uses mechanically created motion to disturb the balance of muscular forces around the shoulder, thereby facilitating dynamic training of the muscles. The hypothesis is that random disturbances provided by the device would potentially in-crease shoulder muscle activation as users try to resist the device’s motion. To test the efficacy of the device, shoulder muscle activation from two groups (ten non-athletes and seven athletes), was assessed in three different shoulder positions and four different exercise conditions (aka configurations). Muscle activation of seven different …

Trochoidal Milling Of Alsicp With Cvd Diamond Coated End Mills, Tony Nguyen

University of the Pacific Theses and Dissertations

Metal matrix composites have seen a rise in demand within the last decade. Aluminum alloy reinforced with silicon carbide particles is a type of particle metal matrix composite that has seen applications in the aerospace, ground transportation, and electronics industry. However, the abrasive SiC particles have made this material difficult to machine through conventional machining strategies. This research will focus on using computer aided manufacturing with trochoidal tool paths to maximize machining productivity and extend the tool life of CVD diamond coated end mills. The focus of this research will be on AlSiCp with a high volume fraction of reinforcement …

Applications Of Low Field Magnetic Resonance Imaging, Muhammad Waqas

University of the Pacific Theses and Dissertations

Magnetic resonance imaging is a non-invasive imaging modality that is used to produce detailed images of soft tissues within the human body. Typically, MRI scanners used in the clinical setting are high field systems because they have a magnetic field strength greater than 1.5 Tesla. The high magnetic field offers the benefit of high spatial resolution and high SNR. However, low filed systems can also produce high resolution MR images with the added benefit of imaging stiffer samples. In this study, a low field 0.5 T MR system was used to image various samples to demonstrate the capability of the …

Moderating Effects Of Age And Experience On The Factors Influencing The Actual Usage Of Cloud Computing, Shailja Tripathi

Journal of International Technology and Information Management

Cloud computing technology (CCT) has attracted extensive attention of organizations to enhance their agility, flexibility and competitive advantage. Successful implementation of CCT depends on its acceptance and useby senior IT managers in the organizations. This study proposes an extended technology acceptance model (TAM) to predict actual CCT usage by the managers. A questionnaire is used to collect the needful data. Exploratory and confirmatory factor analyses are performed to analyze the factor structure and measurement model. Structural equation modeling is used to analyze the structural model. The results supported all the hypotheses of the model. The moderating effect of experience and …

The Silver Lining: A Novel, Inkjet-Printed Mesh Coplanar-Slot Antenna For The Uhf Band, Anastasios C. Karles

UROP Posters

The Federal Communications Commission (FCC) is opening up frequencies within the television range (400MHz to 700MHz) of the Ultra High Frequency (UHF) band for use in emerging technologies, such as cognitive radio networks and machine-to-machine communication. In order for manufacturers to produce affordable antennas that can be used in these emerging technologies, inexpensive antennas are required that meet these new spectrum needs. This paper presents a mesh coplanar-slot bowtie patch antenna fabricated using commercially available inkjet-printing technology. Two antennas were fabricated: a 27x21cm copper FR4 antenna with .25mm lines and a 27x21cm silver antenna with 2mm lines fabricated using inkjet-printing. …

The Role Of Microenvironment Reagent Solubility On Reaction Kinetics Of 4-Nitrophenol Reduction, Michael P. Zeevi, Andrew Harrison, Christina Tang

UROP Posters

The Role of Microenvironment Reagent Solubility on Reaction Kinetics of 4-Nitrophenol Reduction

Michael Zeevi¹ with Andrew Harrison¹ and Christina Tang, PhD¹

¹Department of Chemical and Life Science Engineering, VCU School of Engineering

Introduction: Nanoparticles are of increasing interest due to their high surface area to volume ratio, as well as that they enable fine-tuning of the reaction microenvironment. Through flash nanoprecipitation, core-shell polymer nanoreactors were formed by directed self-assembly. Using the reduction of 4-nitrophenol as a model reduction reaction, we investigated the effect of reagent solubility in the nanoreactor microenvironment’s on nanoreactor kinetics.

Methods: The standard …

Using Crosslinked Hyaluronic Acid (Ha) And Collagen Scaffolds With Sustained Brain-Derived Neurotrophic Factor (Bdnf) Release For Post-Sci Nerve Regeneration, Panth Doshi

UROP Posters

Traumatic events resulting in spinal cord injuries (SCIs) often leave people paralyzed or with partial loss of motor function. The physical disabilities arising from traumatic events prevent people from functioning at the same level as pre-injury. My work aims to identify a plausible method to overcome the inhibitory post-SCI environment and to regenerate nervous tissue in order to restore neural function and, subsequently, motor function. I identified components of a new, hypothetical nerve scaffold based on the immune response after SCIs and the efficacy of currently used scaffolds for nerve regeneration. Hyaluronic acid (HA) polymer scaffolds and collagen-based scaffolds are …

A Time-Efficient Cmos-Memristive Programmable Circuit Realizing Logic Functions In Generalized And-Xor Structures, Muayad Aljafar, Marek Perkowski, John M. Acken, Robin Tan

Electrical and Computer Engineering Faculty Publications and Presentations

This paper describes a CMOS-memristive Programmable Logic Device connected to CMOS XOR gates (mPLD-XOR) for realizing multi-output functions well-suited for two-level {NAND, AND, NOR, OR}-XOR based design. This structure is a generalized form of AND-XOR logic where any combination of NAND, AND, NOR, OR, and literals can replace the AND level. For mPLD-XOR, the computational delay, which is measured as the number of clock cycles, equals the maximum number of inputs to any output XOR gate of a function assuming that the number of XOR gates is large enough to calculate the outputs of the function simultaneously. The input levels …

Subspace Clustering Using Ensembles Of K-Subspaces, John Lipor, David Hong, Yan Shuo Tan, Laura Balzano

Electrical and Computer Engineering Faculty Publications and Presentations

Subspace clustering is the unsupervised grouping of points lying near a union of low-dimensional linear subspaces. Algorithms based directly on geometric properties of such data tend to either provide poor empirical performance, lack theoretical guarantees, or depend heavily on their initialization. We present a novel geometric approach to the subspace clustering problem that leverages ensembles of the K-subspaces (KSS) algorithm via the evidence accumulation clustering framework. Our algorithm, referred to as ensemble K-subspaces (EKSS), forms a co-association matrix whose (i,j)th entry is the number of times points i and j are clustered together by several runs of KSS with random …

Utilizing Data Mining Techniques And Ensemble Learning To Predict Development Of Surgical Site Infections In Gynecologic Cancer Patients, John R. Mcdonough

Graduate Dissertations and Theses

Surgical site infections are costly to both patients and hospitals, increase patient mortality, and are the most common form of a hospital acquired infection. Gynecological cancer surgery patients are already at higher risk of developing an infection due to the suppression of their immune system. This research leverages popular data mining techniques to create a prediction model to identify high risk patients. Implemented techniques include logistic regression, naive Bayes, recursive partitioning and regression trees, random forest, feed forward neural network, k-nearest neighbor, and support vector machines with linear kernel. Weighted stacked generalization was implemented to improve upon the individual base …

Image Series Prediction Via Convolutional Recurrent Neural Networks With Limited Training Data, Zao Zhang

Graduate Dissertations and Theses

This thesis focuses on developing deep learning algorithms that can be used to forecast the image series under limited training data. Specifically, we study the problem of using a pine tree's existing appearance images to predict its future appearance images.

Side-Information For Steganography Design And Detection, Tomas Denemark

Graduate Dissertations and Theses

Today, the most secure steganographic schemes for digital images embed secret messages while minimizing a distortion function that describes the local complexity of the content. Distortion functions are heuristically designed to predict the modeling error, or in other words, how difficult it would be to detect a single change to the original image in any given area. This dissertation investigates how both the design and detection of such content-adaptive schemes can be improved with the use of side-information.

We distinguish two types of side-information, public and private: Public side-information is available to the sender and at least in part also …

Annual Report 2017-2018, Depaul University College Of Computing And Digital Media

CDM Annual Reports

LETTER FROM THE DEAN

I am pleased to share with you the College of Computing and Digital Media’s (CDM) 2017-18 annual report, highlighting the many achievements across our community. It was a big year. We began offering five new programs (two bachelor’s, two master’s, and one PhD) across our three schools, in addition to several new certificate programs through our Institute for Professional Development. We built new, cutting-edge spaces to support these and other programs— most notably a 4,500 square-foot makerspace, a robotics and medical engineering lab, an augmented and virtual reality lab, and plans for a cyber-physical systems project …

Effects Of Predation On The Biochemical Constituents Of The Bleached Soft Coral Sinularia Polydactyla, Carley Elizabeth Cole

Honors Theses

Climate change can indirectly affect the level of predation on soft corals. As sea temperatures rise, more and more bleaching events are occurring, which can affect the production of chemical defenses and the concentrations of the biochemical constituents that make up the soft corals. These changes may make the soft corals more attractive to predators. This phenomenon is suggested by the environmental stress theory (EST), which states that under stressful conditions, more of an organism's energy is allocated to survival rather than to other factors, such as reproduction or predator deterrence. To test the effect of predation on already bleached …

Technique For The Synthesis Of Difluorinated Organic Molecules Using Magnesium Bases, Cassidy S. Baldwin

Honors Theses

The presence of fluorine in organic molecules can confer biological advantages which are often exploited in drug development. For example, fluorine has been shown to limit drug metabolism and enhance drug distribution. However, the development of fluorinated pharmaceutics poses synthetic challenges. These challenges are especially pronounced when developing molecules with a difluoromethyl group. One difluoromethyl functional group of particular interest is the α,α-difluoro-β-amino carbonyl group, which has been seen in potential drug leads. The previous methods of accessing this group are inefficient and complex. The goal of this project was to develop a new technique to access this group by …