Engineering Commons^™

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 …

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 …

Traffic Assignment For Risk Averse Drivers In A Stochastic Network, Ruey L. Cheu, Vladik Kreinovich, Srinivasa R. Manduva

Departmental Technical Reports (CS)

Most traffic assignment tasks in practice are performed by using deterministic network (DN) models, which assume that the link travel time is uniquely determined by a link performance function. In reality, link travel time, at a given link volume, is a random variable. Such stochastic network (SN) models are not widely used because the traffic assignment algorithms are much more computationally complex and difficult to understand by practitioners. In this paper, we derive an equivalent link disutility (ELD) function, for the case of risk averse drivers in a SN, without assuming any distribution of link travel time. We further derive …

Capacity Estimation Of Two-Sided Type C Weaves On Freeway, Phong Thanh Vo

Civil Engineering Dissertations - Archive

A weaving section is a common design on major highway facilities that has been an interest to researchers for years. Weaving areas are characterized by frequent lane changes, which significantly reduce the capacity of the freeway system. The 2000 Highway Capacity Manual (HCM) defined weaving capacity as "any combination of flows that causes the density to reach the LOS E/F boundary condition of 43 pcpmpl for freeways" based on configuration, number of lanes in the weaving section, free-flow speed, length of the weave, and volume ratio (VR). However, no research has been focused on the two-sided type C weaves, which …

Development Of Quality-Aware Video Systems And Nmr Spectrum Registration, Basavaraj Hiremath

Electrical Engineering Theses - Archive

The work introduces a novel concept of Quality-Aware Video (QAV) System and demonstrates its successful implementation. During the course, it develops algorithms for reduced reference video quality assessment and for data hiding. The idea here is to extract quality defining features of the video sequence and embed them in the original video without causing any perceptual changes to obtain QAV. Such a QAV can then be exposed to distortions and adverse attacks that affect the perceptual quality of the video. At the receiving end, the algorithm extracts the quality features of the distorted video, decode the original video quality features, …

Modeling Isotropic Organs Using Beam Models For The Haptic Simulation Of Blunt Dissections Of Bile Duct, Vishal Dalmiya

Electrical Engineering Theses - Archive

Haptic modeling of organs using existing approaches is still not realistic and/or real time. We propose and develop the mathematical foundation of a new approach to modeling organs using beams. Beams are well known entities in Civil and Structural engineering. We develop their mathematical properties in the context of organ characteristics. The real time advantage arises from the fact that a single beam implementation eliminates hundreds, if not thousands of mass springs from the traditional mass spring models and, thousands of polygons from the finite element method (FEM). Even more importantly, our derivation works for both large and small deflections. …

Detection And Opportunistic Spectrum Access In Sensor Networks, Hung Dinh Ly

Electrical Engineering Theses - Archive

This thesis examines target detection problems in Radar Sensor Networks (RSN) and opportunistic spectrum access problem in Cognitive Sensor Networks (CSN). First, studies on the Space-Time Adaptive Processing (STAP) and radar waveform design are provided. Investigation into the target detection performance gain of RSN when STAP and radar waveform design are combined in RSN is then performed. Studies in this thesis show that detection performance of RSN using our proposal is superior to that of a single radar system using STAP only. To further studies on target detection, the multi-target detection problem in RSN is also examined. Signal, interference, and …

Modeling And Simulation Of Cardiovascular Systems, Thomas Wischgoll

Computer Science and Engineering Faculty Publications

No abstract provided.

The Effects Of Foreign Accent And Language On Reaction Time And Accuracy In An Air Traffic Control Task, Rosabelle Suarez

Master's Theses - Daytona Beach

The present study examines the effect of foreign accent interference with the ability to execute commands presented in speech format. The objective of this study was to demonstrate that a foreign accent influences performance. Participants were between 18 and 40 years of age. Half of the participants were native speakers of Spanish who began learning English as a second language via the classroom setting. The other half were native English-speaking with little or no exposure to the Spanish language. The experimental design was similar to an aviation scenario where participants listened to simulated ATC procedural commands and execute them on …

Love Canal Tragedy, Alicia Saunte Phillips, Yung-Tse Hung, Paul A. Bosela

Civil and Environmental Engineering Faculty Publications

The purpose of this environmental failure case study paper is to provide educational materials for environmental engineering courses dealing with design and operation of landfills for hazardous waste. In 1978, it was discovered that hazardous waste had contaminated homes and schools in the Love Canal area, a former chemical landfill which became a 15 acre neighborhood of the City of Niagara Falls, New York. On August 7, 1978, the United States President Jimmy Carter declared a federal emergency at the Love Canal. The Love Canal became the first man-made disaster to receive such a designation based on a variety of …

Dynamic Chracteristics And Stability Analysis Of Muncipal Solid Waste In Bioreactor Landfills, Mohamed Adil Haque

Civil Engineering Dissertations - Archive

Bioreactor landfills are operated to enhance refuse decomposition, gas production, and waste stabilization. The major aspect of bioreactor landfill operation is the recirculation of generated leachate back through the refuse mass. Due to the accelerated decomposition and settlement of solid waste, bioreactor landfills are gaining popularity as an alternative to the conventional landfill designed under Subtitle D regulations. However, recirculation of leachate or addition of water to accelerate the waste decomposition changes the biodegradation and geotechnical characteristics of waste mass. Our understanding of changes in engineering characteristics of solid waste with accelerated decomposition is limited. There is a need to …

Our Legacy Of Neglect: The Longfellow Bridge And The Cost Of Deferred Maintenance, David Westerling, Steve Poftak

Civil Engineering Faculty Publications

The Longfellow Bridge, connecting Boston and Cambridge, is in bad shape, due not only to its age and the ravages of our weather, but also to a troubling and persistent lack of maintenance. Fixing the bridge, in effect paying the bill for our unwillingness to maintain it, is estimated to cost at least $180 million, with the potential for cost overruns reaching into the hundreds of millions. The neglect of the Longfellow Bridge is symptomatic of a problem that encompasses almost all the assets owned by the Commonwealth.

Experiments On Rotational Restraint Of Sheathing, Benjamin W. Schafer

American Iron and Steel Institute (AISI) Specifications, Standards, Manuals and Research Reports (1946 - present)

No abstract provided.

Brillouin-Zone Unfolding Of Perfect Supercells Having Nonequivalent Primitive Cells Illustrated With A Si/Ge Tight-Binding Parameterization, Timothy B. Boykin, Neerav Kharche, Gerhard Klimeck

Birck and NCN Publications

Numerical calculations of nanostructure electronic properties are often based on a nonprimitive rectangular unit cell, because the rectangular geometry allows for both highly efficient algorithms and ease of debugging while having no drawback in calculating quantum dot energy levels or the one-dimensional energy bands of nanowires. Since general nanostructure programs can also handle superlattices, it is natural to apply them to these structures as well, but here problems arise due to the fact that the rectangular unit cell is generally not the primitive cell of the superlattice, so that the resulting E(k) relations must be unfolded to obtain the primitive- …

In Vivo Quantitation Of Rare Circulating Tumor Cells By Multiphoton Intravital Flow Cytometry, Wei He, Haifeng Wang, Lynn C. Hartmann, Ji-Xin Cheng, Phillip S. Low

Other Nanotechnology Publications

Quantitation of circulating tumor cells (CTCs) constitutes an emerging tool for the diagnosis and staging of cancer, assessment of response to therapy, and evaluation of residual disease after surgery. Unfortunately, no existing technology has the sensitivity to measure the low numbers of tumor cells (< 1 CTC per ml of whole blood) that characterize minimal levels of disease. We present a method, intravital flow cytometry, that noninvasively counts rare CTCs in vivo as they flow through the peripheral vasculature. The method involves i.v. injection of a tumor-specific fluorescent ligand followed by multiphoton fluorescence imaging of superficial blood vessels to quantitate the flowing CTCs. Studies in mice with metastatic tumors demonstrate that CTCs can be quantitated weeks before metastatic disease is detected by other means. Analysis of whole blood samples from cancer patients further establishes that human CTCs can be selectively labeled and quantitated when present at approximate to 2 CTCs per ml, opening opportunities for earlier assessment of metastatic disease.

Quantifying The Cognitive, Symptomatic And Neuroendocrine Impact Of The Coriolis Illusion; A Countermeasure For Motion Sickness, Catherine Grandizio

Master's Theses - Daytona Beach

When pilots are unable to accurately perceive the position and motion of their bodies, they are spatially disoriented. Spatial disorientation is often induced by aviation illusions, and its consequences include dizziness, confusion, nausea and fatigue. The present research evaluated the severity of cognitive, neuroendocrine and subjective symptoms of the Coriolis illusion, induced by a spatial disorientation flight training device. Also, the research examined the effectiveness of a mild, ground-based countermeasure, similar to the Coriolis illusion, in reducing the occurrence and severity of symptoms. In the early stages of data analysis, there appeared to be a significant impact of the Coriolis …

Microthruster Experimental Analysis, Amy Denise Richards

Master's Theses - Daytona Beach

The purpose of this study was to design an experimental apparatus that could accurately test and measure the thrust efficiency of conical shaped microthrusters with varying divergence half angles. The experimental apparatus measured the thrust of micronozzles for various feed pressures in vacuum (to duplicate in space operation) as well as ambient. Calibration experiments confirmed the force measurement accuracy of the setup while gas thrust experiments were used to help determine the most efficient divergence half angle. Thrust results were compared to findings from two separate scientific studies that sought to optimize microthruster nozzles using CFD software.

Processing And Properties Of Palm Oil-Based Rigid Polyurethane Foam, S Chuayjuljit, T Sangpakdee, O Saravari

Journal of Metals, Materials and Minerals

Rigid polyurethane (PU) foam has been prepared from palm oil-derived polyol. The polyol was synthesized by transesterification reaction of palm oil and pentaerythritol using calcium oxide as a catalyst. The obtained palm oil-based polyol was reacted with commercial polymeric diphenylmethane diisocyanate in the presence of water (blowing agent), N,N-dimethylcyclohexylamine (catalyst) and polydimethylsiloxane (surfactant) to produce rigid PU foam. The effects of the amount of the catalyst and surfactant on foam properties (i.e. density, compressive strength and thermal behaviors) were studied. It was found that the density of the foams decreased whereas the compressive strength increased with the increasing amount of …

Removal Of Adsorbed Moisture On Iron Powders By Rice Husk Ash, T Luangvaranunt, S Jearwun, K Kondoh

Journal of Metals, Materials and Minerals

Rice husk ash was proposed to be used for removal of adsorbed moisture on iron powders to enhance their flow characteristic. It was produced by burning of rice husk at 700°C for 1 h, using a slowly increasing of heating rate (5°C/min). The burning condition was determined from thermal gravitation analysis of rice husk. The obtained rice husk ash contained 99.7% amorphous silica with large specific surface area of 295 m2 /g. Rice husk ash was effective in removal of adsorbed moisture on iron powders. Adsorption characteristic was found to be isothermal monolayer adsorption. The treated iron powders can be …

Wireless Sensor Network Lifetime Analysis And Energy Efficient Techniques, Haining Shu

Electrical Engineering Dissertations - Archive

Wireless microsensor networks is one of the most important technologies for the 21st century. In distributed sensor networks energy-aware techniques are used to reduce energy consumption. Various sensor network applications have taken energy efficiency into consideration. This thesis report focuses on a new approach based on fuzzy logic systems to analyze the lifetime of a wireless sensor network. It demonstrates that a type-2 fuzzy membership function (MF), i.e., a Gaussian MF with uncertain standard deviation (std) is most appropriate to model a single node lifetime in wireless sensor networks. This research studies two basic sensor placement schemes: square-grid and hex-grid. …

Power Control And Multi-Target Identification In Cognitive Wireless Networks, Hong-Sam Thi Le

Electrical Engineering Theses - Archive

Recent research results have shown that cognitive wireless networks (CWN) have the potential to alleviate spectrum scarcity problem resulting from current policies for radio resource allocation management and dramatically improve the overall performance of communication systems. Unlike conventional wireless networks, which lack the flexibility and adaptation in their operations, CWNs exploit cognitive radio technology which provides cognitive wireless devices with the ability to sense the situation, adapt to the environment and take appropriate actions correspondingly. There have been many challenges in building a fully functional CWN. New developments and approaches need to be proposed to allow radio users to share …

Convergence Or Divergence: Technology Policies And User Expectations

ACUTA: Other Publications

The Forum

Since 1997, the annual ACUTA Forum for Strategic Leadership in Communications Technology has provided a unique opportunity for campus leaders to exchange ideas and discuss issues relevant to the use of technology in meeting the goals of higher education. Held in conjunction with ACUTA's Annual Conference and Exhibtion, this forum brings together men and women of vision, foresight, and authority to discuss strategic directions for the campus of the future.

Goals

• To provide a venue for the examination of issue and challenges facing the higher education community as we grapple with planning, financing, and implementing technology on our …

Nebraska Blueprint - Summer 2007

Nebraska Blueprint (Student Publication)

Table of Contents:

Engineering Alumni Join Peace Corps: Volunteers give back to society by teaching others applicable engineering skills. by Natasha Richardson
Graduate’s Career Lets him Explore Sea and Space: Don Skoumal has notable achievements and involvement in NASA’s Sea Launch Project. by Brian Neilson
Applying Nanotechnology to Tanks: Dean David Allen’s research is helping make tanks lighter and stronger. by Kellie Troxel
A Treatment for Hemophilia Could Start Here: Researchers look for a new treatment to combat this dangerous blood disorder. by Michaela McBride
10 Ways to Get the Most out of Engineering at UNL: A soon-to-be graduate gives …

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 …

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 …

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 …

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 …

Method Of Measuring Permittivity Of Composite Materials With Hexagonal Ferrite Inclusions, Alexander A. Kitaytsev, Gulnur N. Zhumabayeva, Marina Koledintseva

Electrical and Computer Engineering Faculty Research & Creative Works

A new simple method for measuring complex permittivity of substantially lossy composite materials is presented. In this method, a sample of the material under study should completely fill in the cross-section of the single-mode transmission line (waveguide), and the length of the sample must be an integer of a half-wavelength in the waveguide filled with this material. The oscillator frequency is swept linearly, the minima of the reflection coefficient are measured, and then analytical formulas are used to calculate real and imaginary parts of permittivity. The method was tested on magneto- dielectric samples containing hexagonal ferrite powders, as well on …

Online Reinforcement Learning-Based Neural Network Controller Design For Affine Nonlinear Discrete-Time Systems, Qinmin Yang, Jagannathan Sarangapani

Electrical and Computer Engineering Faculty Research & Creative Works

In this paper, a novel reinforcement learning neural network (NN)-based controller, referred to adaptive critic controller, is proposed for general multi-input and multi- output affine unknown nonlinear discrete-time systems in the presence of bounded disturbances. Adaptive critic designs consist of two entities, an action network that produces optimal solution and a critic that evaluates the performance of the action network. The critic is termed adaptive as it adapts itself to output the optimal cost-to-go function and the action network is adapted simultaneously based on the information from the critic. In our online learning method, one NN is designated as the …

Predictive Modeling Of The Effects Of Skew And Imbalance On Radiated Emi From Cables, J. Chen, James L. Drewniak, Richard E. Dubroff, James L. Knighten, Jun Fan, J. Flavin

Electrical and Computer Engineering Faculty Research & Creative Works

This paper provides an approach for predicting the effects of skew and imbalance on radiated emission of cables inside a commercial 19-inch rack-based cabinet. Scattering parameters (S-parameters) for two sets of cable assembly are measured with a four-port vector network analyzer (VNA) and converted into mixed mode S-parameters. Time-domain input signals with different slew rates and different amount of skew are transferred into frequency-domain using fast Fourier transform (FFT). The spectra of radiation emission associated with different inputs are then estimated.