Engineering Commons^™

Study Of Interaction Between Indium Species And Dna In The Formation Of Dna -Templated Nanowires, Shivashankar Suryanarayanan

Doctoral Dissertations

A primary goal of semiconductor industry is to improve device performance and capability by downscaling feature size and upscaling packaging density. As optical-lithography, the mainstream technology for microfabrication, is being stretched to its limit, new unconventional fabrication techniques are being explored as alternatives. A "Bottom-up" approach for manufacturing is emerging as an answer to limitations posed by the traditional "Top-down" approach. Nanowires, bearing the potential of being the basic building blocks for such an approach, are gaining tremendous attention in nanoelectronics. Metal nanowires fabricated using DNA as templates have potential for precise control of length, diameter and positioning. However, wires …

Design And Development Of Microcantilever As A Platform For Moisture Sensing, Qi Chen

Doctoral Dissertations

Ultra-sensitive and selective moisture sensors are needed in various industries for processing control or environmental monitoring. As an outstanding sensor platform, microcantilevers have potential application in moisture detection due to their advantages, such as low-level moisture detection limits, high accuracy, quick response time, high reproducibility, good recovery rate and low in cost. Our research results will lead to the first of its kind for the commercialization of a microcantilever-based moisture sensor used for industrial and household applications. The novelty of the present work is the development of SiO2 and Si cantilevers, which were fabricated using developed processes and modified with …

Development Of An Integrated Opto-Electric Biosensor To Dynamically Examine Cytometric Proliferation And Cytotoxicity, Chang Kyoung Choi

Doctoral Dissertations

My doctoral research has focused on the development of microscale optical techniques for examining micro/bio fluidics. Preliminary work measured the velocity field in a microchannel, by optical slicing, using Confocal Laser Scanning Microscopy (CLSM). Next, Optical Serial Sectioning Microscopy (OSSM) was applied to examine thermometry by detecting the free Brownian motion of nano-particles suspended in mediums at different temperatures. An extension of this work used objective-based Total Internal Reflection Fluorescence Microscopy (TIRFM) to examine the hindered Brownian motion of nano-particles that were very close to a solid surface (within 1 mm).

An optically transparent and electrically conductive Indium Tin Oxide …

Spinning Carbon Fiber Precursors From 1-Butyl-3-Methylimidazolium Chloride Cellulose Solutions, Rhea J. Gelderloos-Sammons

Doctoral Dissertations

Cellulose is an abundant natural renewable polymer that is used in the production of many materials. However, limited processibility and reduced solubility have restricted its use in fibers, films, and other products. Ionic liquids (IL) show promise as a new class of cellulose solvents.

The primary goal of this research was to spin highly oriented and highly crystalline cellulose fibers from an IL solution. These fibers, in addition to their environmentally advantageous processing, have potential as precursors for carbon fibers. The IL selected for this study was 1-butyl-3-methylimidazolium chloride, ([C₄mim]Cl). An elongational flow spinning technique was used to …

Differentiated Intrusion Detection And Svdd-Based Feature Selection For Anomaly Detection, Inho Kang

Doctoral Dissertations

Most of existing intrusion detection techniques treat all types of attacks equally without any differentiation of the risk they pose to the information system. However, certain types of attacks are more harmful than others and their detection is critical to protection of the system. This study proposes a novel differentiated anomaly detection method that can more precisely detect intrusions of specific types of attacks.

Although many researchers have been developed many efficient intrusion detection methods, fewer efforts have been made to extract effective features for host-based intrusion detection. In this study, we propose a new framework based on new viewpoints …

A Study Of Fabrication Of Ultra-High Resolution Nano Devices Through Electron Beam Lithography Process And Its Application To Electron – Optical Systems, Jihoon Kim

Doctoral Dissertations

Today’s semiconductor industry has been significantly changing in its techniques and processes for the fabrication of devices and accordingly, there has been dramatic increase in performance and a reduction in cost. To obtain still higher device performances and still further cost reduction, the dimensions of patterns in integrated circuits should be as small as possible and the 3-dimensional accuracy of multidimensional semiconductor structures should be also achieved as well. The manufacturing of smaller feature dimensions and 3-dimensional devices has been enabled by developments in lithography – the technology which transfers designed patterns onto the silicon wafer. Especially, electron beam lithography …

Design And Evaluation Of A Non-Intrusive Corn Population Sensor, Haizhou Li

Doctoral Dissertations

Specific objectives of this study were to develop, prototype, and test a corn population sensor. Both intrusive mechanical and non-intrusive capacitive techniques have been used to develop the stalk population sensors in previous research. However, neither could generate consistent performance. The mechanical method required high maintenance and resulted in significant underestimations of stalk counts. The performance of capacitive systems was limited by inadequate sensing distance, especially at low stalk moisture levels.

In this research, the sensitivity of the capacitive sensor was optimized for corn stalks. This system utilized a single-sided capacitive sensor, Wien bridge oscillator, phase-locked loop, and an operational …

Intrinsically Evolvable Artificial Neural Networks, Saumil Girish Merchant

Doctoral Dissertations

Dedicated hardware implementations of neural networks promise to provide faster, lower power operation when compared to software implementations executing on processors. Unfortunately, most custom hardware implementations do not support intrinsic training of these networks on-chip. The training is typically done using offline software simulations and the obtained network is synthesized and targeted to the hardware offline. The FPGA design presented here facilitates on-chip intrinsic training of artificial neural networks. Block-based neural networks (BbNN), the type of artificial neural networks implemented here, are grid-based networks neuron blocks. These networks are trained using genetic algorithms to simultaneously optimize the network structure and …

Photogrammetry In Traffic Accident Reconstruction, Lara Lynn O’Shields

Doctoral Dissertations

The aim of this research is to utilize PhotoModeler, a closerange photogrammetry software package, in various traffic accident reconstruction applications. More specifically, three distinct studies were conducted: 1.) vehicle crush measurement, 2.) road curve measurement, and 3.) an evaluation of common traffic accident reconstruction measurement methodologies.

The first study applied the photogrammetric process to controlled crash information generated by the National Highway Traffic Safety Administration (NHTSA). A statistical procedure known as bootstrapping was utilized to generate distributions from which the variability was examined. The “within” subject analysis showed that 44.8% of the variability is due to the technique itself and …

Investigation Of Non-Conventional Bio-Derived Fuels For Hybrid Rocket Motors, Scott Grayson Putnam

Doctoral Dissertations

Non-conventional bio-derived fuels have been evaluated for use in hybrid rocket motors. Tests were conducted at combustion pressures in the range of 100 – 220 psig and thrust levels of 40 – 170 newtons. Beeswax was tested with oxygen as the oxidizer and showed a regression rate at least three times as high as traditional hybrid propellant combinations such as hydroxyl-terminated polybutadiene (HTPB) and liquid oxygen (LOX). This provides the promise of a high thrust hybrid rocket motor using a simple, single port geometry and overcomes the main weakness of traditional hybrid rocket motor propellants, which are low regression rates. …

Investigation Of Magnetic Field Dependent Electroluminescence And Charge Injection In Organic Light Emitting Diodes, Yue Wu

Doctoral Dissertations

After 20 years of development, conjugated polymers have been extensively applied in organic light emitting diodes (OLED), solar cells, transistors, and chemical or bio-sensors. Recently it is discovered that magnetic field can tune the electroluminescence intensity and conductivity in OLEDs, leading to the development of organic magneto-optoelectronics. However, the underlying mechanisms are still unclear.

In this dissertation, we investigated a wide range of conjugated polymers and low molecular weight molecules and proposed that the magnetic field effect on electroluminescence and magnetoresistance arise from the magnetic field enhanced polaron pair dissociation and reduced triplet-charge reaction. The final magnetic field effects are …

Application Of Particulate-Filled Composite (Pfc) Theory To Hot-Mix Asphalt (Hma) Mixtures, Xiang Shu

Doctoral Dissertations

Dynamic modulus (|E*|) of HMA mixtures is one of the fundamental engineering properties measured by the Simple Performance Tester (SPT) and has been incorporated as a basic input parameter in the American Association of State Highway and Transportation Officials (AASHTO) 2002 Mechanistic-Empirical (M-E) Design Guide for flexible pavement design. Although direct laboratory testing and empirical equations (such as the Witczak model and the Hirsch model) provide two ways to obtain the values of dynamic modulus of HMA mixtures, a predictive model based on the microstructure of HMA mixtures is more desirable.

HMA mixtures consist of three phases: aggregate, …

Analysis Of Simulated Electromyography (Emg) Signals Using Integrated Computer Muscle Model, Mohammad Abdul Ahad

Doctoral Dissertations

Introduction

Electromyography (EMG) is a technique used to study the activity of muscle through detection and analysis of the electrical signals generated during muscular contractions. Electromyographic activity is recorded from skeletal muscles to obtain information about their anatomy and physiology. Electromyography, in interplay with various anatomical techniques, provides the present knowledge of the structural organization and the nervous control of muscle. EMG is the prime source of information about the status of the neuromuscular system, and EMG has developed into a diagnostic tool that allows the clinician to follow changes in nerve and muscle caused by neuromuscular diseases.

EMG provides …

Study On Infrastructure Materials Using Neutron Radiography And Diffraction, Xin Luo

Doctoral Dissertations

Advanced nondestructive neutron technology has been utilized to study fundamental issues in the Lost Foam Casting (LFC) process and in the mechanical behavior of infrastructure materials.

Time lapsed neutron radiography combined with digital image processing was used to investigate the real-time LFC process. Behavior and characteristics of the pyrolysis front in the LFC processes were discussed. Evidence shows that neutron radiography offers new insights into the pyrolysis front and the dynamics of the processes involved with the casting. Behavior and characteristics of the pyrolysis front and the molten metal interface in the LFC processes were revealed. The proposed approach will …

Personalized Health Monitoring Using Evolvable Block-Based Neural Networks, Wei Jiang

Doctoral Dissertations

This dissertation presents personalized health monitoring using evolvable block-based neural networks. Personalized health monitoring plays an increasingly important role in modern society as the population enjoys longer life. Personalization in health monitoring considers physiological variations brought by temporal, personal or environmental differences, and demands solutions capable to reconfigure and adapt to specific requirements. Block-based neural networks (BbNNs) consist of 2-D arrays of modular basic blocks that can be easily implemented using reconfigurable digital hardware such as field programmable gate arrays (FPGAs) that allow on-line partial reorganization. The modular structure of BbNNs enables easy expansion in size by adding more blocks. …

A Finite Difference Method For Studying Thermal Deformation In A Three-Dimensional Microsphere Exposed To Ultrashort-Pulsed Lasers, Xudong Du

Doctoral Dissertations

Ultrashort-pulsed lasers with pulse durations on the order of sub-picoseconds to femtoseconds possess the capabilities in limiting the undesirable spread of the thermal process zone in a heated sample which have been attracting worldwide interest in science and engineering. Success of ultrashort-pulsed lasers in real application relies on: (1) well characterized pulse width, intensity and experimental techniques; (2) reliable microscale heat transfer models; and (3) prevention of thermal damage. Laser damage by ultrashort-pulsed lasers occurs after the heating pulse is over since the pulse duration time is extremely short and the heat flux is essentially limited to the region within …

Development And Analysis Of An Internet Browsing Utilizing The Overscan Technique For Persons With Physical Disabilities, Patrick Paul Clerkin

Doctoral Dissertations

Persons with a severe disability often use scanning as an indirect selection technique for operating augmentative and alternative communication aids and computer access. For information that can be organized in advance, including lists of communication elements such as words and phrases, users often employ rate enhancing scanning methods like the row-column scanning technique. However, row-column scanning requires selection elements to be grouped into defined rows and columns, and therefore does not work well with Internet browsing due to the non-grouped layout of HTML pages.

This work attempts to develop an improved scanning technique for Internet browsing by designing interfaces to …

Polymer Light Emitting Diodes Based On Polyfluorenes, Quishu Zhang

Doctoral Dissertations

This dissertation is devoted to the study on Polymer Light-Emitting Diodes (PLEDs) based on polyfluorenes (PFs), a promising class of semiconductive polymers for Light-Emitting Diode (LED) applications. Recently Light Emitting Polymers (LEPs) have clearly made their entry into display technology by virtue of their potential application for large-area flat-panel displays with the advantages of low cost, wide viewing angle, fast switching time, high efficiency, low driving voltage, as well as their flexibility and adaptability. Compared to inorganic materials, the efficiency of PLEDs is, however, still low. And for the application of PFs in PLEDs, an undesired longwavelength emission band is …

Fabrication And Application Of Conducting Polymer Micro- And Nano-Patterns, Anirban Chakraborty

Doctoral Dissertations

Conducting polymers, since their discovery, have attracted significant attention due to their promise of replacing silicon and metals in building devices. They have been shown to have wide applications for biological and chemical sensing as well as for electronic devices. Previous and current efforts have concentrated on building devices of a specific function. When multiple micropatterns of different conducting polymers are fabricated on a common substrate, a versatile microsystem can be envisioned. The existing conducting polymer patterning techniques present some technical challenges of degradation, low throughput, low resolution, depth of field, and residual layer in producing conducting polymer microstructures. To …

Nonlinear Dynamical Analysis Of Brain Electrical Activity Due To Exposure To Weak Environmentally Relevant Electromagnetic Fields, Erik Alfonso Nilsen

Doctoral Dissertations

The reports dealing with the effects of weak electromagnetic fields (EMFs) on brain electrical activity have been inconsistent. We suspected that the use of linear models and their associated methods accounted for some of the variability, and we explored the issue by using a novel approach to study the effects of EMFs on the electroencephalogram (EEG) from rabbits and humans. The EEG was embedded in phase space and local recurrence plots were calculated and quantified to permit comparisons between exposed and control epochs from individual subjects. Statistically significant alterations in brain activity were observed in each subject when exposed to …

Computer Simulation And Human Experiment On The Laplacian Electrocardiogram (Ecg), Ting Chen

Doctoral Dissertations

The electrocardiogram (ECG) provides useful global temporal assessment of cardiac activity, but has limited spatial capabilities. Laplacian electrocardiogram (LECG) and body surface Laplacian mapping (BSLM), improvements over ECG provides high spatiotemporal distributed information about cardiac electrical activation.

This project was divided into two parts: computer simulation and human experiment. In the computer simulation, a comparison of the performance of the tripolar and bipolar as well as spline LECG and BSLMs for localizing and imaging the cardiac electrical activation has been investigated. A simple planar surface model and a simplified eccentric heart-torso sphere-cylinder homogeneous volume conductor model were developed. Multiple dipoles …

Rational Design And Investigation Of Polypeptide Multilayer Films And Capsules, Ling Zhang

Doctoral Dissertations

Three major concerns in the science of materials today are control over structure and function at the molecular level, biodegradability, and scalability of production. Polymeric materials, notably polyelectrolyte multilayer films, have shown considerable promise in all these areas, and for rational development of multifunctionality. Polypeptides constitute an especially interesting class of polyelectrolyte, given their inherent biodegradability, means of control over structure, methods of large-scale synthesis, and ability to encode biological information. Relatively little is known, however, about polypeptide multilayer films, despite recent advances in the general area.

In this dissertation, ten heteropolypeptides were designed and synthesized by Fmoc chemistry. These …

An Intermediate-Layer Lithography Method For Producing Metal Micron/Nano Patterns And Conducting Polymer-Based Microdevices, Xinchuan Liu

Doctoral Dissertations

Metals have been widely used in the areas of integration circuit (IC) and microelectromechanical systems (MEMS) fields as materials for gates, contact pads, interconnects, corrosion resistance coatings, rectifying contacts, redundancy memories, heating elements, mechanical parts, magnetic component, etc. due to their good properties, such as high electrical conductivity and good thermal conductivity. Conducting polymers, because of their promising potential to replace silicon and metals in building devices, have attracted great attention in recent decades.

Traditional photolithography methods are often used to pattern metals and conducting polymers. However, it cannot be used to fabricate nano patterns because the minimum feature size …

An Integrated Fuzzy Inference Based Monitoring, Diagnostic, And Prognostic System, Dustin R. Garvey

Doctoral Dissertations

To date the majority of the research related to the development and application of monitoring, diagnostic, and prognostic systems has been exclusive in the sense that only one of the three areas is the focus of the work. While previous research progresses each of the respective fields, the end result is a variable "grab bag" of techniques that address each problem independently. Also, the new field of prognostics is lacking in the sense that few methods have been proposed that produce estimates of the remaining useful life (RUL) of a device or can be realistically applied to real-world systems. This …

A Programmable Frequency Divider Having A Wide Division Ratio Range, And Close-To-50% Output Duty-Cycle, Mo Zhang

Doctoral Dissertations

In Radio Frequency (RF) integrated circuit design field, programmable dividers are getting more and more attentions in recent years. A programmable frequency divider can divide an input frequency by programmable ratios [1]. It is a key component of a frequency synthesizer. It also can be used to generate variable clock-signals for: switched-capacitor filters (SCFs), digital systems with different power-states, as well as multiple clock-signals on the same system-on-a-chip (SOC). These circuits need high performance programmable frequency dividers, operating at high frequencies and having wide division ratio ranges, with binary division ratio controls and 50% output duty-cycle.

Different types of programmable …

Modular Dc-Dc Converters, Faisal Habib Khan

Doctoral Dissertations

DC-DC converter is one of the mostly used power electronic circuits, and it has applications in various areas ranging from portable devices to aircraft power system. Various topologies of dc-dc converters are suitable for different applications. In high power applications such as the bi-directional dc-dc converter for dual bus system in new generation automobiles, several topologies can be considered as a potential candidate. Regardless of the topology used for this application, the reliability of the converter can be greatly enhanced by introducing redundancy of some degree into the system. Using redundancy, uninterrupted operation of the circuit may be ensured when …

Plastic Deformation And Annealing Of Zr- And Cu- Based Bulk Metallic Glasses, Sujing Xie

Doctoral Dissertations

Plastic deformation in crystalline metals occurs by the motion and multiplication of lattice defects called dislocations, resulting in strain hardening. Metallic glasses, in contrast, lack long-range order; therefore, dislocation-mediated plasticity is not possible in these materials. Metallic glasses undergo plastic deformation through the nucleation and propagation of defects called shear bands, which cause strain softening.

This strain softening can be recovered after annealing, i.e., annealing makes the plastically strained metallic glasses harder, in sharp contrast to the annealing-induced softening typically observed in crystalline metals. During annealing, hardness initially recovers more rapidly in heavily deformed specimens than in lightly deformed ones, …

Process And Temperature Compensated Wideband Injection Locked Frequency Dividers And Their Application To Low-Power 2.4-Ghz Frequency Synthesizers, Rajagopal Vijayaraghavan

Doctoral Dissertations

There has been a dramatic increase in wireless awareness among the user community in the past five years. The 2.4-GHz Industrial, Scientific and Medical (ISM) band is being used for a diverse range of applications due to the following reasons. It is the only unlicensed band approved worldwide and it offers more bandwidth and supports higher data rates compared to the 915-MHz ISM band. The power consumption of devices utilizing the 2.4-GHz band is much lower compared to the 5.2-GHz ISM band. Protocols like Bluetooth and Zigbee that utilize the 2.4-GHz ISM band are becoming extremely popular.

Bluetooth is an …

A Dynamic Study Of An Earth Orbiting Tether Propulsion System, Stephen Edward Stasko

Doctoral Dissertations

Commercial expansion beyond Earth orbit demands efficient, low cost and regular access to space that is not given by current launch systems. An alternative to rocketry has been proposed in the use of tethers as a method of in-space propulsion. One possible implementation of tether propulsion involves the use of a long, vertically oriented tether orbiting the Earth. A suborbital launch vehicle will deliver a payload to the tether’s lower tip, which will then be carried up its length by an elevator car to the upper tip, where the payload is released on a transfer orbit. The orbiting space elevator …

Analysis And Optimization Of Partial Length, Constrained Damping Layers, Shing-Jia Tang

Doctoral Dissertations

A laminated beam with constrained damping layers is analyzed. The normal strain in the longitudinal direction and shear strain in the viscoelastic layer is considered. Hamilton’s principle is used to derive equations of motion and boundary conditions. A 6th order equation is used to describe the portion of the beam covered with a constrained damping layer and a 4th order equation is used to describe the remainder of the beam. The characteristic equations are solved numerically with a gradient-based optimization method in order to determine normalized loss factor values. The loss parameter (normalized loss factor) is shown to be a …