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2006

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Articles 1 - 30 of 3737

Full-Text Articles in Engineering

Energy-Constrained Quality Optimization For Secure Image Transmission In Wireless Sensor Networks, Wei Wang, Dongming Peng, Honggang Wang, Hamid Sharif, Hsiao-Hwa Chen Dec 2006

Energy-Constrained Quality Optimization For Secure Image Transmission In Wireless Sensor Networks, Wei Wang, Dongming Peng, Honggang Wang, Hamid Sharif, Hsiao-Hwa Chen

Faculty Publications from the Department of Electrical and Computer Engineering

Resource allocation for multimedia selective encryption and energy efficient transmission has not been fully investigated in literature for wireless sensor networks (WSNs). In this article, we propose a new cross-layer approach to optimize selectively encrypted image transmission quality in WSNs with strict energy constraint. A new selective image encryption approach favorable for unequal error protection (UEP) is proposed, which reduces encryption overhead considerably by controlling the structure of image bitstreams. Also, a novel cross-layer UEP scheme based on cipher-plain-text diversity is studied. In this UEP scheme, resources are unequally and optimally allocated in the encrypted bitstream structure, including data position ...


Upper Extremity Dynamics During Lofstrand Crutch-Assisted Gait In Children With Myelomeningocele, Brooke A. Slavens, Jamie Frantz, Peter F. Sturm, Gerald F. Harris Dec 2006

Upper Extremity Dynamics During Lofstrand Crutch-Assisted Gait In Children With Myelomeningocele, Brooke A. Slavens, Jamie Frantz, Peter F. Sturm, Gerald F. Harris

Biomedical Engineering Faculty Research and Publications

Background/Objective:

We present a 3-dimensional biomechanical model of the upper extremities to characterize joint dynamics during 2 patterns of Lofstrand crutch-assisted gait in children with myelomeningocele. The upper extremity model incorporates recommendations by the International Society of Biomechanics.

Methods:

A Vicon motion analysis system (14 cameras) captured the marker patterns. Instrumented crutches measured reaction forces. Five subjects with L3 or L4 level myelodysplasia (aged 9.8 ± 1.6 years) were analyzed during reciprocal and swing-through Lofstrand crutch-assisted gait.

Results:

The mean walking speed, cadence, and stride length were greatest during swing-through gait. Although the gait patterns had different morphologies ...


Afci Quarterly Input: Unlv October 1 Through December 31, 2006, Harry Reid Center For Environmental Studies. Nuclear Science And Technology Division Dec 2006

Afci Quarterly Input: Unlv October 1 Through December 31, 2006, Harry Reid Center For Environmental Studies. Nuclear Science And Technology Division

Transmutation Research Program Reports (TRP)

Quarterly report highlighting research projects, activities and objectives of the Transmutation Research Program at the Nuclear Science & Technology Division, Harry Reid Research Center.

The University of Nevada, Las Vegas supports the AFCI through research and development of technologies for economic and environmentally sound refinement of spent nuclear fuel. The UNLV program has four components: infrastructure, international collaboration, student-based research, and management and program support.


A "Divide-And-Conquer" Strategy For Nde Signal Inversion In Gas Transmission Pipelines, Justin Gary Bram Dec 2006

A "Divide-And-Conquer" Strategy For Nde Signal Inversion In Gas Transmission Pipelines, Justin Gary Bram

Theses and Dissertations

Signal inversion in nondestructive evaluation (NDE) applications is a critical step before remediation decisions are made. The accuracy and confidence of the signal inversion results therefore play a key role in evaluating the effectiveness of the NDE procedure. Conventional NDE signal inversion algorithms that employ artificial neural networks treat all geometric regions of the NDE signal equally. Consequently, when the inversion algorithm is presented with input data that is significantly different from the training data, the performance of the network deteriorates significantly. This thesis presents a superior alternative for NDE signal inversion. Different geometric regions of the NDE signature are ...


An Architecture For Intelligent Health Assessment Enabled Ieee 1451 Compliant Smart Sensors, Donald Albert Nickles Dec 2006

An Architecture For Intelligent Health Assessment Enabled Ieee 1451 Compliant Smart Sensors, Donald Albert Nickles

Theses and Dissertations

As systems become increasingly complex and costly, potential failure mechanisms and indicators are numerous and difficult to identify, while the cost of loss is very expensive - human lives, replacement units, and impacts to national security. In order to ensure the safety and long-term reliability of vehicles, structures, and devices attention must be directed toward the assessment and management of system health. System health is the key component that links data, information, and knowledge to action. Integrated Systems Health Management (ISHM) doctrine calls for comprehensive real-time health assessment and management of systems where the distillation of raw data into information takes ...


Data Fusion Of Complementary Information From Parietal And Occipital Event Related Potentials For Early Diagnosis Of Alzheimer's Disease, Nicholas Stepenosky Dec 2006

Data Fusion Of Complementary Information From Parietal And Occipital Event Related Potentials For Early Diagnosis Of Alzheimer's Disease, Nicholas Stepenosky

Theses and Dissertations

The number of the elderly population affected by Alzheimer's disease is rapidly rising. The need to find an accurate, inexpensive, and non-intrusive procedure that can be made available to community healthcare providers for the early diagnosis of Alzheimer's disease is becoming an increasingly urgent public health concern. Several recent studies have looked at analyzing electroencephalogram signals through the use of many signal processing techniques. While their methods show great promise, the final outcome of these studies has been largely inconclusive. The inherent difficulty of the problem may be the cause of this outcome, but most likely it is ...


Multiresolution Wavelet Analysis Of Event-Related Eeg Potentials Using Ensemble Of Classifier Data Fusion Techniques For Early Diagnosis Of Alzheimer's Disease, Apostolos Topalis Dec 2006

Multiresolution Wavelet Analysis Of Event-Related Eeg Potentials Using Ensemble Of Classifier Data Fusion Techniques For Early Diagnosis Of Alzheimer's Disease, Apostolos Topalis

Theses and Dissertations

The recent advances and knowledge in medicine and nutrition have greatly improved our average life expectancy. An unfortunate consequence of this longer life span, however, is a dramatic increase in the number of individuals suffering from dementia, and more specifically, from Alzheimer's disease (AD). Furthermore, AD remains under-diagnosed and under-treated until its more severe stages due to lack of standard diagnostic tools available to community clinics. A search for biomarkers that will allow early diagnosis of the disease is therefore necessary to develop effective medical treatments. Such a biomarker should be non-invasive, simple to obtain, safe, inexpensive, accurate, and ...


Boosted Ensemble Algorithm Strategically Trained For The Incremental Learning Of Unbalanced Data, Michael David Muhlbaier Dec 2006

Boosted Ensemble Algorithm Strategically Trained For The Incremental Learning Of Unbalanced Data, Michael David Muhlbaier

Theses and Dissertations

Many pattern classification problems require a solution that needs to be incrementally updated over a period of time. Incremental learning problems are often complicated by the appearance of new concept classes and unbalanced cardinality in training data. The purpose of this research is to develop an algorithm capable of incrementally learning from severely unbalanced data. This work introduces three novel ensemble based algorithms derived from the incremental learning algorithm, Learn++. Learn++.NC is designed specifically for incrementally learning New Classes through dynamically adjusting the combination weights of the classifiers' decisions. Learn++.UD handles Unbalanced Data through ...


Use Of Principal Component Analysis With Linear Predictive Features In Developing A Blind Snr Estimation System, Matthew James Marbach Dec 2006

Use Of Principal Component Analysis With Linear Predictive Features In Developing A Blind Snr Estimation System, Matthew James Marbach

Theses and Dissertations

Signal-to-noise ratio is an important concept in electrical communications, as it is a measurable ratio between a given transmitted signal and the inherent background noise of a transmission channel. Currently signal-to-noise ratio testing is primarily performed by using an intrusive method of comparing a corrupted signal to the original signal and giving it a score based on the comparison. However, this technique is inefficient and often impossible for practical use because it requires the original signal for comparison. A speech signal's characteristics and properties could be used to develop a non-intrusive method for determining SNR, or a method that ...


Random Feature Subspace Ensemble Based Approaches For The Analysis Of Data With Missing Features, Hussein Syed Mohammed Dec 2006

Random Feature Subspace Ensemble Based Approaches For The Analysis Of Data With Missing Features, Hussein Syed Mohammed

Theses and Dissertations

Missing data in real world applications is not an uncommon occurrence. It is not unusual for training, validation or field data to have missing features in some (or even all) of their instances, as bad sensors, failed pixels, malfunctioning equipment, unexpected noise causing signal saturation, data corruption, and so on, are all familiar scenarios in many practical applications.

In this thesis, the feasibility of an ensemble of classifiers trained on a feature subset space is investigated as an effective and practical solution for the missing feature problem. Two ensemble of classifiers approach motivated by the Random Subspace Method are proposed ...


The Unbalanced Classification Problem: Detecting Breaches In Security, Paul Evangelista Dec 2006

The Unbalanced Classification Problem: Detecting Breaches In Security, Paul Evangelista

West Point ETD

This research proposes several methods designed to improve solutions for security classification problems. The security classification problem involves unbalanced, high-dimensional, binary classification problems that are prevalent today. The imbalance within this data involves a significant majority of the negative class and a minority positive class. Any system that needs protection from malicious activity, intruders, theft, or other types of breaches in security must address this problem. These breaches in security are considered instances of the positive class. Given numerical data that represent observations or instances which require classification, state of the art machine learning algorithms can be applied. However, the ...


Wave Propagation In Nanofibers, Xiangfa Wu, Yuris A. Dzenis Dec 2006

Wave Propagation In Nanofibers, Xiangfa Wu, Yuris A. Dzenis

Faculty Publications from Nebraska Center for Materials and Nanoscience

Surface effect on the longitudinal and flexural wave propagation in straight nanofibers/nanowires is studied within the framework of continuum mechanics. Modified Euler-Bernoulli and Rayleigh-Love rod equations and modified Timoshenko beam equation were developed to take into account the surface effect. It was found that surface tension/stress plays appreciable influence on the wave propagation in nanofibers/nanowires at very small diameters. Wave dispersion relations were presented in closed form, and numerical calculations were performed to show the variation of the phase velocity with the wave number at varying surface property and fiber diameter. The given results can be used ...


Synthesis And Characterization Of Hydrated Rubidium Thio-Hydroxosilicogermanates Using Mechanochemical Hydrothermal Synthesis, Carly R. Nelson, Sarah Olson, Steven A. Poling, Steve W. Martin Dec 2006

Synthesis And Characterization Of Hydrated Rubidium Thio-Hydroxosilicogermanates Using Mechanochemical Hydrothermal Synthesis, Carly R. Nelson, Sarah Olson, Steven A. Poling, Steve W. Martin

Materials Science and Engineering Publications

The synthesis, structure, and proton conductivity of the hydrated thio-hydroxosilicogermanates RbzGexSi1-xSz(OH)4-z·yH2O (2 ≤ z ≤ 3; 0 < y < 1.7) are reported. X-ray diffraction indicates that the z = 2 materials are amorphous and show no unreacted starting materials, which is consistent with the mechanochemical hydrothermal evaporation−precipitation synthesis method. Infrared spectroscopy shows a fully reacted system where both silicon and germanium central anions have vibrational modes at 950, 780, 667, and 450 cm-1 associated with asymmetric modes for Si−O, Ge−O, Si−S, and Ge−S chemical bonds, respectively. O−H stretching and bending modes are present at ...


Interface Characteristics Of Vertically Aligned Carbon Nanofibers For Interconnect Applications, Yusuke Ominami, Quoc Ngo, Makoto Suzuki, Alexander J. Austin, Cary Y. Yang, Alan M. Cassell, Jun Li Dec 2006

Interface Characteristics Of Vertically Aligned Carbon Nanofibers For Interconnect Applications, Yusuke Ominami, Quoc Ngo, Makoto Suzuki, Alexander J. Austin, Cary Y. Yang, Alan M. Cassell, Jun Li

Electrical and Computer Engineering

The authors characterize the detailed interface structure of Ni-catalyzed vertically aligned carbon nanofibers (CNFs) prepared by plasma-enhanced chemical vapor deposition for interconnect applications. Stacked graphitic layers and cup-shape structures of CNFs around the interface region have been observed using high-resolution scanning transmission electron microscopy. The interaction between the Ni catalyst and Ti layer dramatically affects the CNF structure during initial growth. The effect of interface nanostructures on contact resistance is also discussed.


Reduced Loss Through Improved Fabrication For Single Air Interface Bends In Polymer Waveguides, S. Kim, Gregory P. Nordin, Y. Lin, J. Cardenas Dec 2006

Reduced Loss Through Improved Fabrication For Single Air Interface Bends In Polymer Waveguides, S. Kim, Gregory P. Nordin, Y. Lin, J. Cardenas

Faculty Publications

We have previously demonstrated high efficiency small-area 45° single air interface waveguide bends in a perfluorocyclobutyl (PFCB) material system [Opt. Express 12, 5314 (2004)]. In this paper we show how the loss per bend can be decreased through improved bend interface position accuracy and sidewall smoothness. This is achieved with electron-beam lithography (EBL) in a scanning electron microscope (SEM) at the cost of increased fabrication complexity compared to our previous work based on a UV contact mask aligner. Using the EBL-based fabrication process, the measured loss per bend decreases from 0.33 dB/bend to 0.124 dB/bend (97 ...


Elastic Degradable Polyurethanes For Biomedical Applications, Changhong Zhang Dec 2006

Elastic Degradable Polyurethanes For Biomedical Applications, Changhong Zhang

All Theses

Several series of polyurethanes were synthesized with linear or crosslinked structures by using different synthesis routes. Two studies are mentioned: (1) the synthesis of degradable polyurethanes with linear structure and the investigation of the elasticity and cytophilicity of the materials as function of the chain extender, and (2) the synthesis and the investigation of the biocompatibility, degradation, hydrophilicity and mechanical properties of the polyurethane-based hydrogels with crosslinked structure.


Evidence Of Long-Wavelength Collective Excitations In Magnetic Superlattices, Nikolay I. Polushkin, Steven A. Michalski, Lanping Yue, Roger D. Kirby Dec 2006

Evidence Of Long-Wavelength Collective Excitations In Magnetic Superlattices, Nikolay I. Polushkin, Steven A. Michalski, Lanping Yue, Roger D. Kirby

Faculty Publications: Materials Research Science and Engineering Center

We report on a mechanism of dynamic dipolar coupling in magnetic superlattices via long-wavelength nonevanescent fields. In the spin excitation spectra of our heterophase stripe structures, such interactions mediate a singlet ↔ doublet crossover in the frequency regime driven by the orientation of an external static field. This crossover is a new feature observed in collective behavior of superlattices, though there is some analogy of this phenomenon with birefringence taking place in optical superlattices. We envision applying the collective effects described here in microwave photonic devices.


Use Of Friction Stir Processing And Friction Stir Welding For Nitinol Medical Devices, Blair London, Murray Mahoney, Alan Pelton Dec 2006

Use Of Friction Stir Processing And Friction Stir Welding For Nitinol Medical Devices, Blair London, Murray Mahoney, Alan Pelton

Materials Engineering

Metallic materials may be joined utilizing a friction stir processing technique. The friction stir processing technique utilizes a shaped, rotating tool to move material from one side of the joint to be welded to the other without liquefying the base material.


Structuring Emperical Methods For Reuse And Efficiency In Product Development Processes, Marshall Edwin Bare Dec 2006

Structuring Emperical Methods For Reuse And Efficiency In Product Development Processes, Marshall Edwin Bare

Theses and Dissertations

Product development requires that engineers have the ability to predict product performance. When product performance involves complex physics and natural phenomena, mathematical models are often insufficient to provide accurate predictions. Engineering companies compensate for this deficiency by testing prototypes to obtain empirical data that can be used in place of predictive models. The purpose of this work is to provide techniques and methods for efficient use of empirical methods in product development processes. Empirical methods involve the design and creation of prototype hardware and the testing of that hardware in controlled environments. Empirical methods represent a complete product development sub-cycle ...


Stabilisation Of Rail Tracks And Underlying Soft Soil Formations, Buddhima Indraratna, Mohamed A. Shahin, Cholachat Rujikiatkamjorn Dec 2006

Stabilisation Of Rail Tracks And Underlying Soft Soil Formations, Buddhima Indraratna, Mohamed A. Shahin, Cholachat Rujikiatkamjorn

Faculty of Engineering - Papers (Archive)

Construction of rail tracks requires appropriate improvement techniques for ballast and underlying soft formation soil, both of which deform and degrade progressively under heavy train loads. This paper aims to demonstrate and discuss some major aspects in relation to stabilisation of ballasted rail tracks overlaying soft formation soils. The use of geocomposites (i.e. bonded geogrid-geotextile layers) for enhancing the performance of rail tracks is described, with the aim of achieving reduced track settlement, increased resilient modulus and decreased ballast degradation. The effects of increasing the confining pressure on rail tracks in regard to particle breakage are studied using laboratory ...


Wavefront Curvature Sensing From Image Projections, Jonathan C. Buffington Dec 2006

Wavefront Curvature Sensing From Image Projections, Jonathan C. Buffington

Theses and Dissertations

This research outlines the development and simulation of a signal processing approach to real time wavefront curvature sensing in adaptive optics. The signal processing approach combines vectorized Charge Coupled Device (CCD) read out with a wavefront modal estimation technique. The wavefront sensing algorithm analyzes vector projections of image intensity data to provide an estimate of the wavefront phase as a combination of several low order Zernike polynomial modes. This wavefront sensor design expands on an existing idea for vector based tilt sensing by providing the ability to compensate for additional modes. Under the proposed wavefront sensing approach, the physical wavefront ...


Carbon Monoxide Mass Transfer In A Syngas Mixture, Amir Kapic, Samuel T. Jones, Theodore J. Heindel Dec 2006

Carbon Monoxide Mass Transfer In A Syngas Mixture, Amir Kapic, Samuel T. Jones, Theodore J. Heindel

Mechanical Engineering Publications

A myoglobin assay for measuring concentrations of dissolved carbon monoxide (CO) from an artificial synthesis gas blend (20% CO, 18% CO2, 52% N2, and 10% H2) was utilized to determine volumetric CO−water mass-transfer rates in a 0.211-m-diameter stirred-tank reactor (STR). The data are well correlated using the power density and superficial gas velocity, but this correlation is valid only for this STR size. A gas−liquid scale-up model developed for dissolved oxygen mass-transfer rates using air was used to develop a CO−liquid scale-up model for syngas fermentation. The model is applicable in the STR hydrodynamic range associated ...


The Piezoresistive Effect In Microflexures, Gary K. Johns Dec 2006

The Piezoresistive Effect In Microflexures, Gary K. Johns

Theses and Dissertations

The objective of this research is to present a new model for predicting the piezoresistive effect in microflexures experiencing bending stresses. A linear model describing piezoresistivity exists for members in pure tension and compression. Extensions of this model to more complex loading conditions do not match experimental results. An accurate model of piezoresistivity in complex loading conditions would expand the design possibilities of piezoresistive devices. A new model to predict piezoresistive effects in tension, compression, and more complex loading conditions is proposed. The focus of this research is to verify a unidirectional form of this proposed model for microflexures in ...


Dynamics And Structures Of Segregation In A Dense, Vibrating Granular Bed, Jin Sun, Francine Battaglia, Shankar Subramaniam Dec 2006

Dynamics And Structures Of Segregation In A Dense, Vibrating Granular Bed, Jin Sun, Francine Battaglia, Shankar Subramaniam

Mechanical Engineering Publications

We study the rise dynamics of a large particle in a granular bed under vertical vibration using molecular dynamics simulations. Systematic variation of the particle properties and external wall friction in the simulations shows that the large particle rising is very sensitive to external wall friction. The dynamical response of the granular bed with wall friction is shown to include an expansion stage and a compression stage within one cycle. With wall friction, large-scale force networks bearing larger-than-average forces are found in the compression stage. However, without wall friction, large strong force networks do not exist. The distribution of normal ...


Validation Of An Inertial Sensor System For Quantifying Knee Function, Aaron Koslin Dec 2006

Validation Of An Inertial Sensor System For Quantifying Knee Function, Aaron Koslin

All Theses

Gait analysis has become a useful tool for clinicians in evaluating the progression of pathologies through functional analysis. The high cost and dedicated laboratories associated with the traditional camera-based motion analysis systems present the need for an alternative system. Direct measurement of kinetic parameters using inertial sensors (gyroscopes and accelerometers), in place of indirect calculations from position data obtained using cameras, has been shown effective in resolving important gait parameters.
In order to directly compare gait parameters obtained using inertial sensors and a camera system, data was simultaneously collected from both systems for seven test subjects during normal gait. Three ...


Influence Of Socio-Economic And Demographic Factors On Crashes In Rural South Carolina At Sub-County Level, Sunil Jakhadi Dec 2006

Influence Of Socio-Economic And Demographic Factors On Crashes In Rural South Carolina At Sub-County Level, Sunil Jakhadi

All Theses

State of South Carolina ranks high in the fatality rates. The state is a predominately a rural state with more percentage of rural roads. This research focuses on the statistical variation of crash rates between the county and block-group, especially rural once to the state. Also, it focuses on the possibility of various socio-economic and demographic characters influence on the high crash rates particularly in rural South Carolina.
Crash database for the year 2004 was acquired from South Carolina Department of Transportation and was processed by the research team at Clemson University. This processed database was imported into GIS. Spatial ...


Effect Of South Caroline Belt Law On Safety Belt Use, Sourabh Patki Dec 2006

Effect Of South Caroline Belt Law On Safety Belt Use, Sourabh Patki

All Theses

A number of factors and accessories help save lives and prevent injuries to road users, yet safety belts have become synonymous with automobile safety today, unlike any accessory before or since their introduction in automobiles. However, the scientific advances in automobile safety, followed by the acceptance of the necessity for safety in automobiles by both the manufacturers and the population, finally leading to the introduction of safety features and their incorporation within the laws occurred over a much longer span, continuing even today. Today's Safety movement aims at increasing safety belt using an awareness campaigns, accompanied by enforcement. Safety ...


Life Cycle Cost Analysis Of Pavements: State-Of-The-Practice, Zeynep Guven Dec 2006

Life Cycle Cost Analysis Of Pavements: State-Of-The-Practice, Zeynep Guven

All Theses

Life Cycle Cost Analysis (LCCA) is performed by transportation agencies in the design phase of transportation projects in order to be able to implement more economical strategies, to support decision processes in pavement type selection (flexible or rigid) and also to assess the relative costs of different rehabilitation options within each type of pavement. However, most of the input parameters are inherently uncertain. In order to implement the LCCA process in a reliable and trustworthy manner, this uncertainty must be addressed. This thesis summarizes a through research that aims at improving the existing LCCA approach for South Carolina Department of ...


Statistical Methods For Kinetic Modeling Of Fischer Tropsch Synthesis On A Supported Iron Catalyst, Brian L. Critchfield Dec 2006

Statistical Methods For Kinetic Modeling Of Fischer Tropsch Synthesis On A Supported Iron Catalyst, Brian L. Critchfield

Theses and Dissertations

Fischer-Tropsch Synthesis (FTS) is a promising technology for the production of ultra-clean fuels and chemical feedstocks from biomass, coal, or natural gas. Iron catalysts are ideal for conversion of coal and biomass. However, precipitated iron catalysts used in slurry-bubble column reactors suffer from high attrition resulting in difficulty separating catalysts from product and increased slurry viscosity. Thus, development of an active and selective-supported iron catalyst to manage attrition is needed. This thesis focuses on the development of a supported iron catalyst and kinetic models of FTS on the catalyst using advanced statistical methods for experimental design and analysis. A high ...


Optimizing Production Methods For Artifical Silk Proteins Through Bioreactor And Purification Studies Of Recombinant Proteins Expressed From Pichia Pastoris, Aaron Ramey Dec 2006

Optimizing Production Methods For Artifical Silk Proteins Through Bioreactor And Purification Studies Of Recombinant Proteins Expressed From Pichia Pastoris, Aaron Ramey

All Theses

Advancements in the field of biomaterials are being made to produce an artificial silk fiber. A gene was constructed which utilized components from both the dragline silk of Nephila clavipes and nematode collagen. For this engineered protein, the yeast strain Pichia pastoris was chosen to be the host organism. Previous research has shown P. pastoris to have comparatively low amounts of specific protein productivity. Therefore, this problem must be compensated for by obtaining extremely high cell densities. The main focus of this study was to optimize the fermentation parameters of transgenic yeast cultures within a bioreactor in order to increase ...