Engineering Commons^™

Evaluating The Impact Of Adopting 3d Printing Services On The Retailers, Sharareh Rajaei Dehkordi

Dissertations

As additive manufacturing technology becomes more responsive to consumers’ demand, one important question for the retailers is whether they should provide 3D printing services in their brick-and-mortar store in addition to the traditional off-the-shelf product? If so, what should be the retailers pricing scheme to achieve a higher profit? What should be the optimal inventory level of off-the-shelf products? What is the optimal capacity of 3D printers? In this study, stochastic models are examined to capture the joint optimal 3D product price and capacity of 3D printers to maximize retailer’s expected profit while considering consumer product choices. Moreover, a stochastic …

Comparative Analysis Of The Dissolution Performance Of Aspirin Tablets In The Usp Apparatus 2 And In A Minivessel Dissolution System, Annmarie C. Walker

Theses

Dissolution testing is a critical component of quality control procedures in the pharmaceutical industry in order to ensure that the final solid dosage forms have consistent dissolution properties. Dissolution tests are also routinely conducted to evaluate the in-vitro performance of solid dosage forms during pharmaceutical development, to aid in the behavior of formulations, and to optimize drug release from dosage forms.

The use of compendial dissolution test apparatus and techniques, such as the USP 2 (Paddle), to characterize the dissolution performance of oral drug delivery system is an established area of pharmaceutical science. However, this method is not always appropriate, …

Electrical Properties Of Metal/Wse2structures, Zeel Rajiv Gandhi

Theses

The formation of low resistance metal contacts on two-Dimensional layer (2-D) of WSe2 is a big challenge. In this research, a comparative study is presented on the electrical properties of metal/WSe2 Schottky barrier diodes with various metals such as Au, In, Al, and Ga in the temperature range of 80K to 400K well within the domain of thermionic emission theory.

Topics covered here include the factors that determine the Schottky barrier height, the device capacitance, and its current-voltage (I-V) characteristics. I-V curves for different metals on WSe2 are analyzed as function of temperature. Barrier height is determined from Au-nWSe2 Schottky …

Carbon Fiber Electrodes For In Vivo Neural Recording, Esma Cetinkaya

Theses

Multi-channel micro electrodes for neural recording is a growing field that thrives on novel materials and fabrication techniques offered by micro fabrication technology. The material and the design of microelectrodes have a critical role on the quality of neural signals recorded. The neural signals collected by chronic implantation of these devices in experimental animals reveal new information about the brain functions and guide the development of new diagnostic and treatment options for neurological disorders.

Ideally, a microelectrode should meet two important criteria: longevity after implantation and minimal tissue insult. Carbon fibers` high tensile strength and flexibility allow fabrication of micro-scale …

Formulation Of Uv Curable Resins Utilized In Vat Photo Polymerization For The Additive Manufacturing Of Gun Propulsion Charge In 3d Printers, David T. Bird

Theses

Formulating resins for Additive Manufacturing (AM), utilizing UV laser stereolithography, is a new technique that makes it possible for the fabrication of complex geometries with high dimensional resolution. This layer by layer photopolymerization approach spans various industrial sectors from adhesives, inks and optical fibers to nanotechnology and biomaterials. UV curable resins such as epoxides, vinyl ethers and other acrylates are important monomers that offer effective mediums for energetic materials, and the potential exists to develop environmentally friendly formulations with suspended energetic materials at various solids loading levels.

Developing techniques for UV curing formulations of highly loaded energetic suspensions is a …

Computational And Experimental Determination Of The Mixing Efficiency Of A Microfluidic Serpentine Micromixer, Siril Arockiam

Theses

In microfluidics, efficiency and mixing time are the greatest disadvantages. These parameters hinder the application of microfluidic devices for biochemical and immunological assays. However, once these disadvantages have been overcome by optimizing the parameters of the microfluidic device, it becomes the important analytical tool. In this experiment, various designs of microfluidic devices have been both simulated using COMSOL software, and experimentally verified to obtain the optimized parameter such as depth and velocity for better mixing efficiency. The COMSOL model has been validated by comparing the results with fluorescent images data of the experiment. The microfluidic device is built with Adhesive …

A Novel E-Voting System With Diverse Security Features, Haijun Pan

Dissertations

Internet-based E-voting systems can offer great benefits over traditional voting machines in areas, such as protecting voter and candidate privacy, providing accurate vote counting, preventing voter fraud, and shortening the time of vote counting. This dissertation introduces, establishes and improves Internet-based E-voting systems on various aspects of the voting procedure. In addition, our designs also enable voters to track their votes which is a very important element in any elections.

Our novel Internet-based E-voting system is based on the following realistic assumptions: (1) The election authorities are not 100% trustworthy; (2) The E-voting system itself is not 100% trustworthy; (3) …

Appointment Planning And Scheduling In Primary Care, Babak Hoseini

Dissertations

The Affordable Care Act (ACA) puts greater emphasis on disease prevention and better quality of care; as a result, primary care is becoming a vital component in the health care system. However, long waits for the next available appointments and delays in doctors offices combined with no-shows and late cancellations have resulted in low efficiency and high costs.

This dissertation develops an innovative stochastic model for patient planning and scheduling in order to reduce patients’ waiting time and optimize primary care providers’ utility. In order to facilitate access to patients who request a same-day appointment, a new appointment system is …

Machine Learning Based Digital Image Forensics And Steganalysis, Guanshuo Xu

Dissertations

The security and trustworthiness of digital images have become crucial issues due to the simplicity of malicious processing. Therefore, the research on image steganalysis (determining if a given image has secret information hidden inside) and image forensics (determining the origin and authenticity of a given image and revealing the processing history the image has gone through) has become crucial to the digital society.

In this dissertation, the steganalysis and forensics of digital images are treated as pattern classification problems so as to make advanced machine learning (ML) methods applicable. Three topics are covered: (1) architectural design of convolutional neural networks …

Aerosol Transport By Coughing In A Depressurized And Air-Conditioned Chamber, Bo Zhang

Dissertations

Expiratory droplets from human coughing in an air-conditioned environment have always been considered to be potential carriers of pathogens, responsible for respiratory disease transmission. The air movement/circulation and ambient conditions such as pressure and temperature are all key factors of aerosol transport. To study the transmission of disease by human coughing in a depressurized air-conditioned chamber, there are many technical challenges, including the following: 1) the study of simulating human coughing; 2) the collection of aerosol generated by coughing; 3) the CFD simulation of coughing-induced aerosol transport in an air-conditioned chamber; 4) the validation of such a CFD simulation by …

An Artificial Neural Network Model For Predicting Freeway Work Zone Delays With Big Data, Bo Du

Dissertations

Lane closures due to road reconstruction and maintenance have resulted in a major source of non-recurring congestion on freeways. It is extremely important to accurately quantify the associated mobility impact so that a cost-effective work zone schedule and an efficient traffic management plan can be developed. Therefore, the development of a sound model for predicting delays or road users is desirable.

A comprehensive literature review on existing work zone delay prediction models (i.e., deterministic queuing model and shock wave model) is conducted in this study, which explores the advantages, disadvantages, and limitations of different modeling approaches. The performance of those …

Silicon-Germanium Nanowire Heterojunctions: Optical And Electrical Properties, Xiaolu Wang

Dissertations

Semiconductor nanowires are quasi-one-dimensional objects with unique physical properties and strong potential in nanophotonics, nanoelectronics, biosensing, and solar cell devices. The next challenge in the development of nanowire functional structures is the nanowire axial heterojunctions, especially lattice mismatched heterojunctions. Si and Ge have a considerable lattice mismatch of ~ 4.2% as well as a mismatch in the coefficient of thermal expansion, and the formation of a Si_1-xGe_x transition layer at the heterointerface creates a non-uniform strain and modifies the band structures of the adjacent Si and Ge nanowire segments. These nanostructures are produced by catalytic chemical …

Formulation And Dissolution Of Polymer Strip Films For The Delivery Of Poorly Water-Soluble Drug Nanoparticles, Scott Matthew Krull

Dissertations

Polymer films have emerged as a promising platform for delivery of pharmaceutical products in recent years due to simplified processing, greater flexibility, and improved patient compliance over traditional solid dosage forms. However, the large majority of efforts have focused on incorporation of water-soluble drugs. The objective of this dissertation is to explore the robustness and versatility of the strip film platform for delivery of poorly water-soluble drug nanoparticles to ultimately develop a predictive model for drug release from such films.

The robustness of the polymer strip film platform to successfully deliver a variety of poorly water-soluble drug nanoparticles without the …

Field Induced Assembly Of Particulate Systems, Kinnari Shah

Dissertations

The primary focus of the first part of this dissertation is to study the AC field-driven assembly of monodisperse silica and glass particles on liquid - liquid interface and forming a liquid film of uniform thickness having arrangement of particles on it. This liquid film with arrangement of regular particles can be converted into a solid film by curing top UV curable liquid. Here, electric field is used as a tool to facilitate AC field-driven assembly. The work describes the assembly of different size of regular particles and effective development of solid film.

It is also shown that particles of …

Optimization Of The Front End Of Cdte Solar Cells, Yunfei Chen

Dissertations

The front end of CdTe solar cells consists of two layers: a transparent conducting oxide (TCO) layer and a window layer. New wider band gap materials, ZnMgO are being used to replace CdS as the window layer for the purpose of removing blue loss. For ZnMgO, three important parameters, including the atomic Mg content (x), thickness (t), and doping concentration (n) can play important roles on the performance of CdTe solar cells. In this dissertation, systematic simulation, by solar cell capacitance simulator (SCAPS), and experiments are used to investigate the influences of these …

Co2 Reduction Over Noble Metal/Carbon Nanotube Catalyst, Yuan Zhu

Dissertations

Carbon nanotube-based Pt/Pd and Ru catalysts, independently synthesized by a microwave reaction technique, show good catalytic activity for CO2 reduction in the contexts of dry reforming (DR) of methane (CH₄ + CO₂ -> 2CO + 2H₂) and reverse water gas shift (RWGS) (H2 + CO₂ -> CO + H₂O). Reaction temperatures range from 773 to 973 K, with system pressure at 30 psig. The feed molar ratios CH4/CO₂ and CO₂/H₂ are varied from 0.5 to 2.0. Reactant conversions in DR and RWGS are strongly influenced by temperature and feed …

Assessment Of Nanocomposites Vs. Amorphous Solid Dispersions For Dissolution Enhancement Of Bcs Class Ii Drugs, Meng Li

Dissertations

Nanoparticle-based formulations (nanocomposites) and amorphous solid dispersions, shortly ASDs, are two major pharmaceutical formulation platforms used for the bioavailability enhancement of poorly water-soluble drugs. While they both have several advantages-disadvantages, a scientific comparative assessment of their drug release performance and dissolution mechanisms at different drug doses is not available. With the goal of addressing this issue, the dissertation aims to achieve three major objectives: (1) develop a processing-formulation understanding of wet media milling process for fast-efficient production of drug nanoparticles in stable nanosuspension form, (2) elucidate the impact of various classes dispersants on drug release rate and mechanisms during the …

Modeling Subconcussive And Cumulative Subconcussive Impacts Using A Lateral Fluid Percusion Injury Device, Todd Long

Dissertations

Repetitive mTBI and concussion are a major risk factor for developing long-term cognitive and behavioral impairments. Curiously, cumulative head injuries sustained over an individuals’ career, involving contact activities (e.g. athletes and military personnel), are beginning to be implicated in long-term consequences, such as dementia. Recently, chronic traumatic encephalopathy (CTE) has gained momentum in the science and medical community as a neurodegenerative disease of repetitive head injuries. CTE was observed at autopsy of former athletes that did not closely correlate with a clinical history of concussion. Thus, suggesting cumulative subconcussive insults may induce long-term damage.

Investigating the etiology of subconcussive and …

Characterization Of Microporous Ectfe Membranes Exposed To Different Liquid Media And ?-Radiation And Nanoparticle Microfiltration Through Such Membranes, Na Yao

Dissertations

Microporous polymeric membranes are used in a variety of applications for separations, purification as well as barrier function. A major application is for microfiltration (MF). Changes in the properties of MF membranes exposed to acids, bases and organic solvents are of interest in semiconductor processing as well as in membrane contactor applications. Microfiltration membranes used for sterilization in beverage, biotechnology and pharmaceutical industries are sterilized by gamma radiation among others. Irradiation-induced degradation in membrane properties should be known. A variety of fluoropolymer-based microporous membranes are available with varying properties. Ethylene chlorotrifluoroethylene (ECTFE) membranes are a new addition and are of …

Erosion Behavior And Scour Risk Of Extremely Coarse Streambeds, Abolfazl Bayat

Dissertations

Bridge scour, which is the erosion of soil and rock around bridge abutments and piers, is the principal cause of bridge failure in the United States and around the world. Previous investigations of scour have focused mostly on fine sediments such as sand, silt, and small gravel, because such alluvium underlies a majority of bridges. The erosion resistance of coarser sediments has received limited attention to date, even though they dominate many small to medium-size rivers in the northern tiers of the United States, Europe, and Asia. This study focuses on the scour behavior of extremely coarse particles (ECP), namely …

Simulation, Performance And Interference Analysis Of Multi-User Visible Light Communication Systems, Adel Aldalbahi

Dissertations

The emergence of new physical media such as optical wireless, and the ability to aggregate these new media with legacy networks motivate the study of heterogeneous network performance, especially with respect to the design of protocols to best exploit the characteristics of each medium.

This study considers Visible Light Communications (VLC), which is expected to coexist with legacy and future radio frequency (RF) media. While most of the research on VLC has been done on optimizing the physical medium, research on higher network layers is only beginning to gain attention, requiring new analyses and tools for performance analysis.

The first …

Estimating Vehicles Emissions At Signalized Intersections In The Highway Capacity Manual, Yuanyuan Fan

Dissertations

Over the past decades, motor vehicle volumes have continued to increase at a high rate. As a result, engineers in the transportation field not only need more robust knowledge of traffic operation control and transportation planning, but more attention is also needed to understand and estimate the influences that this increasing volume of vehicles has on the environment, especially the influence on air quality. The EPA has stated that reducing carbon monoxide (CO) from vehicle emissions is the most significant way to control air pollution from the transportation sector.

The Highway Capacity Manual is a national and international resource that …

Interaction Of Voluntary Activity And Functional Electrical Stimulation In The Upper Extremity As A Method For Short-Term Alteration Of Corticospinal Excitability And Force Control, Katherine Maia Gerton

Theses

Repetitive movement training (RMT) is a well-established method for rehabilitating functional movement. However, many stroke survivors are not able to participate in RMT for the necessary duration to produce results due to rapid muscle fatigue or inability to perform the desired movement at all. Often, functional electrical stimulation (FES) is applied passively, as a rehabilitative therapy, to stroke subjects who are unable to participate in RMT. The effects of voluntary contraction and FES are not well understood for the upper extremity following a stroke. This experiment was designed to elucidate the mechanisms of functional and neurophysiological changes associated with combining …

Spatial And Temporal Deformation Pattern Of The Brain From Blunt Trauma, Abdus Ali

Theses

It is widely accepted that under extreme loadings the soft tissue of the brain will deform inside the skull, creating large amounts of both stress and strain on the tissue. This can result in a focal injury, or in the case of acceleration and deceleration, diffuse injuries. Any attempt at understanding the underlying mechanisms and effects of TBI, have to start by focusing on what is actually occurring within the brain. The objective of this experiment is to record differences in the spatial and temporal patterns of deformation within the brain during blunt trauma when changing impact parameters. A linear …

Subject And Group Level Changes And Comparison In Functional Connectivity Under Low Vs. High Cognitively Demanding Naturalistic Viewing Conditions Using Fmri, Rakibul Hafiz

Theses

Resting State fMRI is used extensively for analysing brain regions. fMRI is also used to determine task induced activations from cerebral networks. This study involves both rest and task activation data and implements statistical methods applied on Blood Oxygenation Level Dependent (BOLD) signals. The conventional task based designs are very specific and may not reflect day to day activities. The two task conditions in this study are watching a movie called INSCAPE with low cognitive load and segments of contextual Hollywood movies under continuous and natural conditions.

The aim is to investigate individual and group level Functional Connectivity changes between …

Iterative Learning Control For Improved Tracking Of Fluid Percussion Injury Device, Steve Susanibar

Theses

Traumatic brain injury (TBI) afflicts over 10 million people around the world. Injury to the brain can occur from a variety of physical insults and the degree of disability can greatly vary from person to person. It is likely that the wide range of TBI outcomes may be due to the magnitude, direction, and forces of biomechanical insult acting on the head during such TBI events. Lateral Fluid Percussion (FPI) brain injury is one of the most commonly used and well-characterized experimental models of TBI. A Fluid Percussion Injury (FPI) device in the laboratory is used to replicate the injury …

Numerical Simulation For Identification Of Insects Using A Cw Lidar System, Christo Videlov

Theses

Mosquitos are the most common vector of disease in the world, causing millions of deaths a year. While curing the diseases they cause is one approach to this problem, another could be to avoid the mosquitos in the first place. Knowing their flight patterns, location, and population in one area could aid in this. Additionally, classifying the mosquitos in an area would be helpful. The age and sex of the mosquito is important to find as they affect the chances of the insect carrying diseases such as malaria or yellow fever.

Many current methodologies to monitor insects are based on …

Study On The Dispersion Of Particles At A Fluid-Liquid Interface And Its Application In Hydrophilous Pollination, Naga Aditya Musunuri

Dissertations

This dissertation work describes the physics of particle adsorption and the spontaneous dispersion of powders that occurs when they come in contact with a fluid-liquid interface and its application in hydrophilous pollination of Ruppia Maritima, an aquatic plant. The dispersion of particles can occur so quickly that it appears explosive, especially for small particles on the surface of mobile liquids like water. PIV (Particle Image Velocimetry) measurements show that the adsorption of a spherical particle at the interface causes an axisymmetric streaming flow about the vertical line passing through the particle center. The fluid directly below the particle rises upward, …

Mobile Cloud Computing And Network Function Virtualization For 5g Systems, Ali Al-Shuwaili

Dissertations

The recent growth of the number of smart mobile devices and the emergence of complex multimedia mobile applications have brought new challenges to the design of wireless mobile networks. The envisioned Fifth-Generation (5G) systems are equipped with different technical solutions that can accommodate the increasing demands for high date rate, latency-limited, energy-efficient and reliable mobile communication networks.

Mobile Cloud Computing (MCC) is a key technology in 5G systems that enables the offloading of computationally heavy applications, such as for augmented or virtual reality, object recognition, or gaming from mobile devices to cloudlet or cloud servers, which are connected to wireless …

Fast Estimation Model Of Pressure-Temperature Response For Planning Focused Ultrasound Surgery, Tariq Mohammad Arif

Dissertations

High Intensity Focused Ultrasound (HIFU) is becoming a widely accepted modality for extracorporeal non-invasive hyperthermia and surgical procedures. Since ultrasonic transducers need to operate in various challenging body locations, the arrangement of their array elements can be optimized to improve the capability of controlling focus intensity. In the first part of this dissertation, patterns of pressure field variations with several selected design variables (kerf, transducer element’s number and element’s width-height) are studied. These patterns indicate that there is a more suitable shape and arrangement of transducer elements in a specified area to achieve highest possible pressure. In order to obtain …