Engineering Commons^™

Computational Studies Of Ion Transport In Polymer Electrolytes, Hui Wu

Doctoral Dissertations

Improving ionic conductivity and lithium mobility in polymer electrolytes is important for their practical use for battery electrolytes. In this study, a combination of molecular dynamics and Monte Carlo simulations was used to bring insight into lithium ion transport in poly(ethylene oxide) (PEO) with plasticizers and also next to alumina solid surface doped with lithium salt. The simulations were performed using a moderately high molecular weight polymer (Mn = 10,000 g/mol) at an EO:Li ratio of 15. For the plasticized system, the PEO with LiN(CF3SO 2)2 (LiTFSI) was mixed with 10 wt% plasticizers that included either cyclic ethylene carbonate …

Role Of Ammonia In The Activiation Of Methanol Dehydrogenase/Cytochrome C(L) Enzyme, Ancy Kunjumon

Doctoral Dissertations

Recent advancement in enzyme catalysis has opened ways to design efficient biocatalysts, bio-sensors and bio-fuel cells. An in-depth knowledge about the mechanism of the reaction taking place within the enzymes is of great importance to achieve these goals. In this dissertation, various computation methods are applied to investigate the mechanism behind enzyme catalysis in the presence of compounds called activators.

Methanol dehydrogenase (MDH) is a well-known bio-catalyst that can oxidize excess of methanol from the environment to formaldehyde. The enzyme works well within the bacterial environment, but under in vitro, it loses activity. Ammonia is used as an activator …

Experimental And Numerical Evaluation Of Cured In Place Pipe Lining System For High Temperature Applications In Sewer Pipes, Shaurav Z. Alam

Doctoral Dissertations

Some of the older cities across North America and Europe had been using steam driven HVAC systems since beginning of the last century. Consolidated Edison (Con Ed.) of New York operates the New York City steam system, the largest commercial district heating system in the world, with more than 100 miles of transmission and distribution pipes serving Manhattan Island. Other steam district systems exist in San Francisco, Harrisburg, Minneapolis, Pittsburgh, San Diego, and Detroit, some dating back to 1903. In those cities the sewer pipes are used as venues for discharging the waste steam condensate from the HVAC system.

The …

Plasma-Activated Fusion Bonding For Vacuum Encapsulation Of Microdevices, Joel Soman

Doctoral Dissertations

A fabrication process for vacuum-encapsulating PZT microcantilevers was designed in this dissertation. Initially, a low temperature wafer-bonding recipe was optimized with the help of plasma-activation. Conventional direct fusion bonding temperature was reduced from 400°C to 85°C, and final thermal annealing temperature and time of 1000°C for 4 hours (hr) were significantly reduced to 300°C and 1 hr respectively. Tensile tests conducted on dies diced from the bonded wafer stack revealed bond strengths of 22.15 MPa, which was close to the bulk fracture strength of 24 MPa for silicon. Near infrared images of the wafer stack showed no debonded regions at …

Passive Micromixers And Organic Electrochemical Transistors For Biosensor Applications, Senaka Krishna Kanakamedala

Doctoral Dissertations

Fluid handling at the microscale has greatly affected different fields such as biomedical, pharmaceutical, biochemical engineering and environmental monitoring due to its reduced reagent consumption, portability, high throughput, lower hardware cost and shorter analysis time compared to large devices. The challenges associated with mixing of fluids in microscale enabled us in designing, simulating, fabricating and characterizing various micromixers on silicon and flexible polyester substrates. The mixing efficiency was evaluated by injecting the fluids through the two inlets and collecting the sample at outlet. The images collected from the microscope were analyzed, and the absorbance of the color product at the …

Introducing Porous Silicon As A Sacrificial Material To Obtain Cavities In Substrate Of Soi Wafers And A Getter Material For Mems Devices, Wajihuddin Mohammad

Doctoral Dissertations

Microelectromechanical system (MEMS) resonators have been a subject of research for more than four decades. The reason is the huge potential they possess for frequency applications. The use of a MEMS resonator as the timing element has an experimental history and huge progress has been made in this direction. Vacuum encapsulated MEMS resonators are required for high precision frequency control. Hence, a device with a high quality factor and durability is needed. In this effort, a new process for producing a cavity in the substrate of Silicon on insulator (SOI) MEMS devices and augmenting it with a getter using porous …

Modeling And Control For Heave Dynamics Of A Flexible Wing Micro Aerial Vehicle Distributed Parameter System, Lisa M. Kuhn

Doctoral Dissertations

In recent years, much research has been motivated by the idea of biologically-inspired flight. It is a conjecture of the United States Air Force that incorporating characteristics of biological flight into air vehicles will significantly improve the maneuverability and performance of modern aircraft. Although there are studies which involve the aerodynamics, structural dynamics, modeling, and control of flexible wing micro aerial vehicles (MAVs), issues of control and vehicular modeling as a whole are largely unexplored. Modeling with such dynamics lends itself to systems of partial differential equations (PDEs) with nonlinearities, and limited control theory is available for such systems.

In …

A Deterministic Method Of Predicting Long-Term Pile Capacity In Cohesive Soils After The Dissipation Of Excess Pore Water Pressure, Eric J. Steward

Doctoral Dissertations

Pile setup or freeze is a phenomenon where the bearing capacity of a pile increases over time both during and after the dissipation of pore pressure and the stabilization of lateral earth pressure. Driven piles gain capacity after installation because of the dissipation of excess pore pressure and soil aging. Incorporating accurate setup prediction into the design of the piles can significantly reduce the cost of many projects by reducing the size or number of required piles. Various simple, empirical mathematical models have been developed to predict pile setup. However, these models are often unreliable, resulting in very conservative designs. …

Nanofabrication Of Halloysite-Pcl Composite Scaffolds And Functionalization Of Titanium For Tissue Regeneration, Shraddha Parshottambhai Patel

Doctoral Dissertations

Major medical needs may be achieved through regenerative medicine. Nanotechnology has triggered a research revolution in many important areas such as the biomedical sciences and bioengineering at the molecular level which has grown significantly due to the availability of new analytical applications and tools based on nanotechnology. Clinical conditions and diseases being targeted by nanotechnology research include burns, Alzheimer's and Parkinson's disease, implant failure, improved wound healing, birth defects, osteoporosis and congestive heart defects. Therapeutic use of growth factors and drugs to stimulate the production and/or function of endogenous cells represents a key area of regenerative medicine. The development of …

Design, Behavior, And Performance Of Precast Concrete Bridge Barriers, Walid Rajab Alaywan

Doctoral Dissertations

The guidelines proposed by the NCHRP Report 350 pertaining to the safety of roadway hardware devices necessitated the evaluation of those devices. This study deals with the strength evaluation of precast concrete bridge railing.

A literature review was performed before the start of the study. Though many articles, reports, and publications were found regarding the testing of cast-in-place concrete barriers, such similar publications pertaining to precast concrete bridge railing were almost non-existent.

The theoretical work was performed using the yield line theory to predict the strength of the precast barrier. Though the theory was developed for cast-in-place barriers where the …

Predicting Deterioration Rate Of Culvert Structures Utilizing A Markov Model, Chenguang Yang

Doctoral Dissertations

A culvert is typically a hydraulic passage, normally placed perpendicular to the road alignment, which connects the upstream and downstream sections underneath an embankment, while also providing structural support for earth and traffic loads. The structural condition of culverts continues to deteriorate due to aging, limited maintenance budgets, and increased traffic loads. Maintaining the performance of culverts at acceptable levels is a priority for the U.S. Department of Transportation (DOT), and an effective maintenance of culvert structures can be greatly improved by introducing asset management practices. A priority list generated by traditional condition assessment might not provide optimum solutions, and …

Ultrasonic Assisted Layer-By-Layer Assembly For Stable Nanocolloids Of Curcumin And Paclitaxel, Zhiguo Zheng

Doctoral Dissertations

Researchers have been trying to fight cancer with synthesis of new bioactive compounds but many of these novel drugs have low solubility in water and it is difficult to deliver them into a patient's body. One way of solving this particular problem is to use nanoscale drug delivery systems. In this dissertation, we describe using an ultrasonic assisted layer-by-layer encapsulation process to prepare anti-cancer drugs with 50∼200 nm particle size with designed coating to achieve sustained release and target delivery.

Two methods for systematic manufacture of low solubility anti-cancer drug nanoparticles were proposed: I) Top-down approach to breakdown larger drug …

Advanced Thermal Models For Improved Design Of Counter Flow Microchannel Heat Exchangers, Bobby Mathew

Doctoral Dissertations

Theoretical models of counter flow microchannel heat exchangers subjected to scaling and secondary effects are developed in this dissertation. The scaling effects studied include axial heat conduction and viscous dissipation, while the secondary effects considered in this dissertation is that of external heat transfer via heat flux and temperature. The theoretical models developed are one-dimensional and consist primarily of ordinary governing equations that describe the axial variation of hot and cold fluid. For the case of axial heat conduction, the axial variation of wall temperature is also modeled. The models are dependent on various factors, such as Reynolds number, Prandtl …

An Integrated Circuit/Microsystem/Nano-Enhanced Four Species Radiation Sensor For Inexpensive Fissionable Material Detection, Randy Paul Waguespack

Doctoral Dissertations

Small scale radiation detectors sensitive to alpha, beta, electromagnetic, neutron radiation are needed to combat the threat of nuclear terrorism and maintain national security. There are many types of radiation detectors on the market, and the type of detector chosen is usually determined by the type of particle to be detected. In the case of fissionable material, an ideal detector needs to detect all four types of radiation, which is not the focus of many detectors. For fissionable materials, the two main types of radiation that must be detected are gamma rays and neutrons. Our detector uses a glass or …

Development Of Approximating Functions To Model And Predict The Properties Of Fresh And Hardened Fly Ash-Based Geopolymer Concrete, Eleazar Ivan Diaz Loya

Doctoral Dissertations

The manuscript presented herein is based on the investigation of the mechanical properties of fly ash-based geopolymer concrete and their link to fly ash (FA) characteristics. A database of 32 FA samples was created. Each FA sample was analyzed in terms of chemical composition, crystallographic properties and particle size distribution. The mechanical performance of geopolymer concrete (GPC) made from each FA sample was evaluated in terms of density, setting time, compressive and flexural strength, static elastic modulus and Poisson's ratio. It is worth mentioning that the author has already published preliminary results of this study (Diaz and Allouche, 2010; Diaz …

Manipulating Cellular Growth Responses To Patterning, Apoptotic, And Environmental Cues, James N. Mcnamara

Doctoral Dissertations

In this work, various methods of controlling cell growth are examined. Cell-cell interaction, apoptotic cues, three dimensional scaffolds, and non-adherent environments are evaluated for their ability to affect the differentiation, morphology, and growth rate of different cell types. Previous work has shown that cell growth and cell morphology can be influenced by patterns of polymers coated on surfaces in two dimensions, designated here as the x and y dimensions of a standard Cartesian coordinate system. Tissue engineering and regenerative medicine studies have shown limited success in modifying growth in the third, z dimension. This work considers not only the x, …

A Modeling And Simulation Framework For Electrokinetic Nanoparticle Treatment, James Phillips

Doctoral Dissertations

The focus of this research is to model and provide a simulation framework for the packing of differently sized spheres within a hard boundary. The novel contributions of this dissertation are the cylinders of influence (COI) method and sectoring method implementations. The impetus for this research stems from modeling electrokinetic nanoparticle (EN) treatment, which packs concrete pores with differently sized nanoparticles. We show an improved speed of the simulation compared to previously published results of EN treatment simulation while obtaining similar porosity reduction results. We mainly focused on readily, commercially available particle sizes of 2 nm and 20 nm particles, …

Sub Pixel Analysis And Processing Of Sensor Data For Mobile Target Intelligence Information And Verification, Theresa Allen Williams

Doctoral Dissertations

This dissertation introduces a novel process to study and analyze sensor data in order to obtain information pertaining to mobile targets at the sub-pixel level. The process design is modular in nature and utilizes a set of algorithmic tools for change detection, target extraction and analysis, super-pixel processing and target refinement. The scope of this investigation is confined to a staring sensor that records data of sub-pixel vehicles traveling horizontally across the ground. Statistical models of the targets and background are developed with noise and jitter effects. Threshold Change Detection, Duration Change Detection and Fast Adaptive Power Iteration (FAPI) Detection …

Data Mining Based Learning Algorithms For Semi-Supervised Object Identification And Tracking, Michael P. Dessauer

Doctoral Dissertations

Sensor exploitation (SE) is the crucial step in surveillance applications such as airport security and search and rescue operations. It allows localization and identification of movement in urban settings and can significantly boost knowledge gathering, interpretation and action. Data mining techniques offer the promise of precise and accurate knowledge acquisition techniques in high-dimensional data domains (and diminishing the “curse of dimensionality” prevalent in such datasets), coupled by algorithmic design in feature extraction, discriminative ranking, feature fusion and supervised learning (classification). Consequently, data mining techniques and algorithms can be used to refine and process captured data and to detect, recognize, classify, …

Investigation Of Microbubble/Droplet Formation In Cross-Flow And Co-Flow Micro Devices, Tom J. John

Doctoral Dissertations

The primary goal of the work presented in this dissertation is to generate microbubbles of a diameter of less than 15μm inside micro channels. In order to achieve this detailed understanding, the facts and limitations behind the generation of microbubbles inside a micro channel are determined from existing literature. The major limitations of the current bubble/droplet generators are found to be the bubble confinement effect, the merging of bubbles, the difficulty in determining bubble diameter and the need for smaller channels to generate smaller bubbles. A device eliminating these drawbacks is conceptualized, and its feasibility is studied using COMSOL® and …