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2010

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Articles 3931 - 3960 of 5375

Full-Text Articles in Engineering

Innovations In ¹H Mr Tissue Oximetry: New Probes And Pulses, Ujjawal Rastogi Jan 2010

Innovations In ¹H Mr Tissue Oximetry: New Probes And Pulses, Ujjawal Rastogi

Bioengineering Theses - Archive

Low oxygenation level (hypoxia) of tissue leads to cellular dysfunction, damage and poor response to therapy. Quantitative measurement of tissue oxygenation is critical not only for the study of tissue physiology, but could also help improve efficacy of therapeutic procedures. Our group has previously developed and implemented a novel approach to quantify oxygen tension in tissue using ¹H MRI, known as “PISTOL” (Proton Imaging of Siloxanes to map Tissue Oxygenation Levels). It exploits a linear relationship between the longitudinal relaxation rate (R1) and oxygen tension (pO₂) of a reporter molecule (probe). Due to close proximity of fat (~ 1 ppm) …

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A Study Of The Physiological Effects Of Sleep Apnea On Cerebral Blood Flow Velocity, Gauri Bhave Jan 2010

A Study Of The Physiological Effects Of Sleep Apnea On Cerebral Blood Flow Velocity, Gauri Bhave

Bioengineering Theses - Archive

It is estimated that sleep apnea is prevalent in the US in about 18 million people. The prevalence rate is approximately 6% in the US. Sleep apnea reduces the quality of life of patients. Sleep apnea is characterized by repetitive pauses in breathing during sleep. Recent studies also show loss of gray matter in people diagnosed with sleep apnea. To study the physiological effects of sleep apnea on cerebral blood flow velocity (CBFV), CBFV was measured in subjects simulating apnea. Sixteen volunteers (29 ± 5 yr and BMI 24.1±4.8, 9M and 7F) were recruited as control subjects. We measured CBFV …

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An Investigation Of Peripheral Blood Volume And Oxygen Saturation Change In Obstructive Sleep Apnea, Swathi Iyer Jan 2010

An Investigation Of Peripheral Blood Volume And Oxygen Saturation Change In Obstructive Sleep Apnea, Swathi Iyer

Bioengineering Theses - Archive

Obstructive sleep apnea (OSA) is a type of sleep disordered breathing in which the airway collapse partially or fully and causes arousal to resume breathing. In a 2009 National sleep foundation poll of 1000 people, 63% of men and 50% of the females showed signs of sleep apnea. It also showed that subjects with sleep apnea have high risk of high blood pressure, stroke and mental disorders such as depression especially in female. Also by another group of researcher it has been shown that the prevalence of OSA is 4% in male and 2% in female. It has been also …

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In Vivo Tracking Of Mesenchymal Stem Cell Recruitment To Tissue Scaffolds, Manwu Sun Jan 2010

In Vivo Tracking Of Mesenchymal Stem Cell Recruitment To Tissue Scaffolds, Manwu Sun

Bioengineering Theses - Archive

The term "Stem cells" has been extensively used to describe precursor undifferentiated cells that have the capacity to self-renew and can also give rise to multiple tissue types. Many studies have been shown improved functional outcome after treated with stem cell therapy. However, almost all of these investigations were analyzed based on histological evaluations which are time-consuming, expensive and fail to provide 3 dimensional and real-time information about stem cell responses. Therefore, there is a need for the development of new method to investigate the migration of stem cells in vivo. Recent evidence supports that fluorescence imaging system offer both …

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Attenuation Based Quantification Of Interstitial Lung Disease Using High Resolution Computed Tomography And Correlation With Pulmonary Function Tests, Snehal S. Watharkar Jan 2010

Attenuation Based Quantification Of Interstitial Lung Disease Using High Resolution Computed Tomography And Correlation With Pulmonary Function Tests, Snehal S. Watharkar

Bioengineering Theses - Archive

Interstitial lung disease (ILD) is a chronic and progressive pulmonary disease of the lung parenchyma resulting in fibrotic scar formation of the pulmonary alveoli. The pathologic changes in the lung result in restrictive impairment of lung function. High resolution computed tomography (HRCT) of the chest has become an essential technique in diagnosing and assessing the extent of ILD. Clinical evaluation by HRCT is usually qualitative, leading to inter-observer variability particularly in detecting early disease. We propose a quantitative attenuation-based analysis to standardize the assessment of regional lung disease. We hypothesize that early ILD is associated with greater regional heterogeneity than …

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A Micromechanics Model Of Thermal Expansion Coefficient In Fiber Reinforced Composites, Nittapon Srisuk Jan 2010

A Micromechanics Model Of Thermal Expansion Coefficient In Fiber Reinforced Composites, Nittapon Srisuk

Mechanical and Aerospace Engineering Theses - Archive

Fiber reinforced composites are widely used for the various applications in the aerospace, automotive, infrastructures and sporting goods industries. The evaluations of its mechanical and thermal properties are needed for accurate estimation of their structural response. In this study, a mathematical closed-form expression of unit cell model was developed to estimate the coefficient of thermal expansion (CTE) along longitudinal and transverse directions of unidirectional lamina. Unlike the previous models, the present model takes into consideration of the fiber configuration and volume fraction of each constituent in the unit cell. In addition, the model is also able to obtain the stresses …

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Dynamic Thermal Management Of Multi Core Processors Using Core Hopping, Avinash Raghu Jan 2010

Dynamic Thermal Management Of Multi Core Processors Using Core Hopping, Avinash Raghu

Mechanical and Aerospace Engineering Theses - Archive

Multi core processors are the order of the day today. The demand for greater levels of performance and the consequent increase in design complexity have rendered the single core processor obsolete and resulted in more cores being put onto a single chip. Processors incorporating more than 4 cores on a chip are dubbed many core processors. This, while improving performance, has lead to increased power densities. Also, the power distribution across the die surface is not uniform. These factors together, result in heat being concentrated at specific points on the die surface, called `hot spots'.The increase in die temperature results …

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Mean Pressure Measurements Of Micro-Vortex Generator At Mach 2.5, Yusi Shih Jan 2010

Mean Pressure Measurements Of Micro-Vortex Generator At Mach 2.5, Yusi Shih

Mechanical and Aerospace Engineering Theses - Archive

Shock wave/boundary layer interactions (SBLIs) are always an important issue for high-speed vehicles. SBLIs reduce the performance of aerodynamic surfaces and engine inlets, amongst a number of adverse effects. Micro-vortex generators (MVGs) are a potential flow control method that has seen intense investigation recently and have even been implemented in actual configurations at low speeds. The present research is focused on the mean pressures at Mach 2.5 around an MVG. Experiments were performed with a baseline flat plate and also with two MVG configurations (70 and 45 trailing edge) mounted ahead of a 5° ramp. In the present study MVGs …

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Axial Wave Propagation In Truncated Cones, Bhumil A. Diwanji Jan 2010

Axial Wave Propagation In Truncated Cones, Bhumil A. Diwanji

Mechanical and Aerospace Engineering Theses - Archive

While dealing with problems of impact analysis, where the force is dependent on the time, one can use the transient analysis to compute the response. Transient wave propagation has drawn interest from a long time mainly because of the way structural members behave when subjected to high rates of loading. Solutions to these problems find applications in the design of various mechanical equipments, or any situation where rigid objects are impacting on structural members.The first part of this study deals with the axial wave propagation in cones of different apex angles using transient analysis in ANSYS. The results from the …

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Fiber-Optic Pressure Sensor For Time-Of-Flight Measurements In A Shock Wave, Karthikeyan Jagadevan Jan 2010

Fiber-Optic Pressure Sensor For Time-Of-Flight Measurements In A Shock Wave, Karthikeyan Jagadevan

Mechanical and Aerospace Engineering Theses - Archive

Fiber-optic sensors are widely employed to detect pressures and temperatures precisely. In particular, MEMS-based Ber-optic sensors are immune to electromagnetic interference but may have limitations at high temperatures as encountered in combustors. To ensure high-temperature survivability, such sensors may be bondedanodically. This project explains the development of a Ber-optic pressure sensor utilizing intensity based principle whereby a fused silica optical window was glued to the tungsten carbide enclosure. The development was estimated to determine high pressures of up to at least 3.5 MPa (507 psi). The sensor is designed to capture the pressure pulse and the time-of-flight (TOF) of a …

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Peak Stress Of Composite Multiple-Hole Laminates With And Without Patch, Sakthivel Selvaraj Jan 2010

Peak Stress Of Composite Multiple-Hole Laminates With And Without Patch, Sakthivel Selvaraj

Mechanical and Aerospace Engineering Theses - Archive

In repairing of composite structures, the damage in the composite laminate is usually removed in the form of circular cutouts which results in holes in the laminate. Then a patch laminate is adhesively bonded to the damaged composite laminate. The presence of holes in any structures creates a high stress concentration at the edge of the hole which indeed reduces the life of the structure. The primary objective of this study is to investigate the high stress of the damaged laminate with different hole patterns and the effect of having single and double patches with various configurations on these hole …

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Computational Model For Transient And Steady State Analysis Of A 1-Dimensional Auto-Thermal Reformer, Srikanth Honavara Prasad Jan 2010

Computational Model For Transient And Steady State Analysis Of A 1-Dimensional Auto-Thermal Reformer, Srikanth Honavara Prasad

Mechanical and Aerospace Engineering Theses - Archive

This study presents a 1-dimensional mathematical model of steam reformer to be used with high temperature solid oxide fuel cell (SOFC). Steam reforming (SR) is widely used in industries to produce hydrogen from hydrocarbons. There are various physical processes associated with chemical reactions in the SR of methane such as mass, heat and momentum transport. In this study a one-dimensional SR reactor with built-in preheater and mixing chamber connected to fuel gas and steam reservoirs is modeled and analyzed. The main part of the reformer is a metallic tube with catalyst coating on the inner walls, and it can be …

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Concurrent Masters Degrees Across The Atlantic: Innovations, Issues And Insights, Michael Dyrenfurth, Mike Murphy, Gary Bertoline, Robert Herrick, Kathryne Newton, Gareth O'Donnell, Donal Mchale, Nuria Castell, Miquel Barcelo, Didac Balas, Maria Ribera Sancho, Jordi Garcia Jan 2010

Concurrent Masters Degrees Across The Atlantic: Innovations, Issues And Insights, Michael Dyrenfurth, Mike Murphy, Gary Bertoline, Robert Herrick, Kathryne Newton, Gareth O'Donnell, Donal Mchale, Nuria Castell, Miquel Barcelo, Didac Balas, Maria Ribera Sancho, Jordi Garcia

Conference papers

Atransatlantic degree consortium to implement a four-semester dual masters degree initiative across a three-institution consortium consisting of Purdue University (USA), the Technological University Dublin (DIT), and the Universitat Politècnica de Catalunya (Spain) is presented in this paper.

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Quality Indicators For Engineering And Technology Education, Michael Dyrenfurth, Mike Murphy, Gary Bertoline Jan 2010

Quality Indicators For Engineering And Technology Education, Michael Dyrenfurth, Mike Murphy, Gary Bertoline

Conference papers

In recent years the development and use of university rankings, comparisons, and/or league tables has become popular and several methodologies are now frequently used to provide a comparative ranking of universities. These rankings are often based on research and publication activity and also not uncommonly focus on indicators that can be measured rather than those that should be measured. Further, the indicators are generally examined for the university as a whole rather than for university divisions, departments or programs. Implicit also is that placement in the rankings is indicative of quality. This paper provides an overview of the methodologies used …

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Self-Assembly Of Polystyrene Nanospheres And Its Applications As Templates For Plasmonic Structures, Shih-Hsin Chang Jan 2010

Self-Assembly Of Polystyrene Nanospheres And Its Applications As Templates For Plasmonic Structures, Shih-Hsin Chang

Material Science and Engineering Dissertations - Archive

Monodispersed colloidal polystyrene spheres have been self-assembled into various structures as templates for the fabrication of different nanostructures. Two unique self-assembly processes have been developed and systematically investigated. A method to make the multi-layer and mono-layer close-packed structure by means of capillary-convective force has been developed. By directly visualizing the self-assembling process using optical microscopy, a mechanism based on the 2-D crystal formation and 3-D repulsive force model has been proposed to explain the process. A vertical deposition technique to produce nanosphere crystal structure with single orientation on hydrophilic glass substrate has also been developed. Using a lithographically patterned substrate …

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Modeling Studies To Assess Long Term Settlement Of Light Weight Aggregate Embankment, Seema Kalla Jan 2010

Modeling Studies To Assess Long Term Settlement Of Light Weight Aggregate Embankment, Seema Kalla

Civil Engineering Theses - Archive

Expanded clay and shale (ECS) is a low weight material derived from clay and shale, and has been used in large quantities throughout the world. Very few studies have been performed to investigate the behavior of ECS and how it can reduce the settlements of embankments when used as a fill material. This thesis presents research findings of numerical modeling to assess the long term settlements of ECS embankment on a soft clay deposit and supports both pavement and traffic loading. Observed settlements near the pavement of a light weight ECS embankment built on soft clay indicated that this material …

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Field Investigations On Performance Of Short Drilled Shafts Under Inclined Loading, Richard S. Williammee Jr Jan 2010

Field Investigations On Performance Of Short Drilled Shafts Under Inclined Loading, Richard S. Williammee Jr

Civil Engineering Theses - Archive

In the Kaufman County area within the Texas Department of Transportation's Dallas District, several short drilled shaft foundations supporting three-cable median barrier systems wereobserved to be distressed during severe winter storm conditions in late 2006 through early 2007. A research study was initiated at UT Arlington to determine and understand the mechanisms causing these shaft failures. The ends of the three-cable median barrier systems are fastened to a single drilled shaft foundation. In general, these shafts are short in depth and of the same dimensions, diameter, and depth. They are typically used in all soil conditions. This paper presents the …

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Effect Of Frame Shape And Geometry On The Global Behavior Of Rigid And Hybrid Frame Under Earthquake Excitations, S.M. Ashfaqul Hoq Jan 2010

Effect Of Frame Shape And Geometry On The Global Behavior Of Rigid And Hybrid Frame Under Earthquake Excitations, S.M. Ashfaqul Hoq

Civil Engineering Theses - Archive

The primary focus of this study is to present a shape which will improve building performance in earthquake excitations. The investigation started with 3-, 9-, 12- and 20-story rectangular frame. The seismic performance is observed for different earthquake data with different frequency content. Then, the Rhombus shape is introduced to compare with the Rectangular shape frames, keeping the height-to-width ratio and loading same. For the first part of the investigation, deflection and member forces are compared between rhombus and rectangular shape considering all connections rigid. In the second part of the study partially restrained connections are introduced in mid levels …

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Investigation Of The Lower Bound Compressive And Flexural Strengths Of Conventional Concrete And Clay Masonry, Benchmark Henry Harris Jan 2010

Investigation Of The Lower Bound Compressive And Flexural Strengths Of Conventional Concrete And Clay Masonry, Benchmark Henry Harris

Civil Engineering Theses - Archive

Conventional masonry is a handcrafted product in which units are placed by hand in a mortar bedding that is prepared during construction. TMS 402 Building Code Requirements for Masonry Structures (also referred to by the industry as the Masonry Standards Joint Committee or MSJC) and referenced standards consequently permit a range of various field conditions so as to allow practical construction (1). The primary objective of the testing program was to measure a statistically significant number of test results to investigate the lower bound compressive and flexural strengths of conventional concrete and clay masonry under simulated field conditions.96 compression tests …

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Effect Of Leachate Recirculation On Methane Generation Of A Bioreactor Landfill, Shahed R. Manzur Jan 2010

Effect Of Leachate Recirculation On Methane Generation Of A Bioreactor Landfill, Shahed R. Manzur

Civil Engineering Theses - Archive

Municipal solid waste (MSW) disposal is of current concern due to the green-house effect and rising temperature all around the globe. Landfill gas is generated from aerobic & anaerobic biodegradation of organic materials in municipal solid waste (MSW) landfill. Along with leachate, generation of Methane happens to be a by-product of the entire biodegradation process in MSW landfills. Conventional landfilling or dry cell concept minimizes the amount of moisture infiltration into the waste. In contrast, Enhanced Leachate Recirculation (ELR) or bioreactor operation facilitates leachate recirculation and distribution through the landfill that leads both reduction of time for waste stabilization and …

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Parameter Estimation In Heat Transfer And Elasticity Using Trained Pod-Rbf Network Inverse Methods, Craig Rogers Jan 2010

Parameter Estimation In Heat Transfer And Elasticity Using Trained Pod-Rbf Network Inverse Methods, Craig Rogers

Electronic Theses and Dissertations

In applied mechanics it is always necessary to understand the fundamental properties of a system in order to generate an accurate numerical model or to predict future operating conditions. These fundamental properties include, but are not limited to, the material parameters of a specimen, the boundary conditions inside of a system, or essential dimensional characteristics that define the system or body. However in certain instances there may be little to no knowledge about the systems conditions or properties; as a result the problem cannot be modeled accurately using standard numerical methods. Consequently, it is critical to define an approach that …

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Gravity-Induced Wrinkling In Subscale, Singly Curved Parabolic Gossamer Membrane, Jack Leifer, David C. Jones, Adam M. Cook Jan 2010

Gravity-Induced Wrinkling In Subscale, Singly Curved Parabolic Gossamer Membrane, Jack Leifer, David C. Jones, Adam M. Cook

Engineering Faculty Research

No abstract provided.

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Particle Separation Through Taylor-Couette Flow And Dielectrophoretic Trapping, Christopher Paul Bock Jan 2010

Particle Separation Through Taylor-Couette Flow And Dielectrophoretic Trapping, Christopher Paul Bock

Electronic Theses and Dissertations

As the world population approaches seven billion, a greater strain is put on the resources necessary to sustain life. One of the most basic and essential resources is water and while two thirds of the earth is covered by water, the majority is either salt water (oceans and seas) or it is too contaminated to drink. The purpose of this project is to develop a portable device capable of testing whether a specific source of water (i.e. lake, river, well…) is potable. There are numerous filtration techniques that can remove contaminants and make even the dirtiest water clean enough for …

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Modeling And Design Of Multi-Port Dc/Dc Converters, Zhijun Qian Jan 2010

Modeling And Design Of Multi-Port Dc/Dc Converters, Zhijun Qian

Electronic Theses and Dissertations

In this dissertation, a new satellite platform power architecture based on paralleled three-port DC/DC converters is proposed to reduce the total satellite power system mass. Moreover, a fourport DC/DC converter is proposed for renewable energy applications where several renewable sources are employed. Compared to the traditional two-port converter, three-port or four-port converters are classified as multi-port converters. Multi-port converters have less component count and less conversion stage than the traditional power processing solution which adopts several independent two-port converters. Due to their advantages multi-port converters recently have attracted much attention in academia, resulting in many topologies for various applications. But …

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Correlation Between Preparation Parameters And Properties Of Molybdenum Back Contact Layer For Cigs Thin Film Solar Cells, Eigo Takahashi Jan 2010

Correlation Between Preparation Parameters And Properties Of Molybdenum Back Contact Layer For Cigs Thin Film Solar Cells, Eigo Takahashi

Electronic Theses and Dissertations

Molybdenum (Mo) thin film back contact layers for thin film CuIn(1-x)GaxSe2 (CIGS) solar cells were deposited onto soda lime glass substrates using a direct current (DC) planar magnetron sputtering deposition technique. Requirements for the Mo thin film as a back contact layer for CIGS solar cells are various. Sheet resistance, contact resistance to the CIGS absorber, optical reflectance, surface morphology, and adhesion to the glass substrate are the most important properties that the Mo thin film back contact layer must satisfy. Experiments were carried out under various combinations of sputtering power and working gas pressure, for it is well known …

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Experimental Studies Of The Heat Transfer Characteristics Of Silica Nanoparticle Water-Based Dispersion In Pool Boiling Using Nichrome Flat Ribbons And Wires, Diane Marie Vazquez Jan 2010

Experimental Studies Of The Heat Transfer Characteristics Of Silica Nanoparticle Water-Based Dispersion In Pool Boiling Using Nichrome Flat Ribbons And Wires, Diane Marie Vazquez

Electronic Theses and Dissertations

This work deals with a study of enhanced critical heat flux (CHF) and burnout heat flux (BHF) in pool boiling of water with suspended silica nanoparticles using ribbon-type and wire heaters. Previously our group and other researchers have reported three-digit percentage increase in critical heat flux in silica nanofluids. This study investigates the effect of various heater surface dimensions and cross-sectional shapes on pool boiling heat transfer characteristics of water and water-based nanofluids. CHF and BHF were analyzed for circular and rectangular cross-section nichrome wires and ribbons of increasing sizes in the range of 0.32mm to 2.38mm width, approaching a …

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The Development Of A Human-Centric Fuzzy Mathematical Measure Of Human Engagement In Interactive Multimedia Systems And Applications, Chandre Butler Jan 2010

The Development Of A Human-Centric Fuzzy Mathematical Measure Of Human Engagement In Interactive Multimedia Systems And Applications, Chandre Butler

Electronic Theses and Dissertations

The utilization of fuzzy mathematical modeling for the quantification of the Human Engagement is an innovative approach within Interactive Multimedia applications (mainly video-based games designed to entertain or train participants on intended topics of interest) that can result in measurable and repeatable results. These results can then be used to generate a cogent Human Engagement definition. This research is designed to apply proven quantification techniques and Industrial/Systems Engineering methodologies to nontraditional environments such as Interactive Multimedia. The outcomes of this research will provide the foundation, initial steps and preliminary validation for the development of a systematic fuzzy theoretical model to …

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High-Density And High-Efficiency Soft Switching Modular Bi-Directional Dc-Dc Converter For Hybrid Electric Vehicles, John Elmes Jan 2010

High-Density And High-Efficiency Soft Switching Modular Bi-Directional Dc-Dc Converter For Hybrid Electric Vehicles, John Elmes

Electronic Theses and Dissertations

This dissertation1 presents the design of a high-density and high-efficiency soft-switching bi-directional DC-DC converter for hybrid-electric vehicles. The converter operates in a new bidirectional interleaved variable-frequency quasi-square-wave (QSW) mode, which enables high efficiency, high switching frequency, and high power-density. The converter presented utilizes a new variable frequency interleaving approach which allows for each module to operate in an interleaved position while allowing for tolerance in inductance and snubber capacitor values. The variable frequency interleaved soft-switching operation paired with a high-density nanocrystalline inductor and high-density system structure results in a very high performance converter, well exceeding that of the current technology. …

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Robust Dialog Management Through A Context-Centric Architecture, Victor C. Hung Jan 2010

Robust Dialog Management Through A Context-Centric Architecture, Victor C. Hung

Electronic Theses and Dissertations

This dissertation presents and evaluates a method of managing spoken dialog interactions with a robust attention to fulfilling the human user’s goals in the presence of speech recognition limitations. Assistive speech-based embodied conversation agents are computer-based entities that interact with humans to help accomplish a certain task or communicate information via spoken input and output. A challenging aspect of this task involves open dialog, where the user is free to converse in an unstructured manner. With this style of input, the machine’s ability to communicate may be hindered by poor reception of utterances, caused by a user’s inadequate command of …

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Heat Transfer In Multi-Layer Energetic Nanofilm On Composites Substrate, Navid Amini Manesh Jan 2010

Heat Transfer In Multi-Layer Energetic Nanofilm On Composites Substrate, Navid Amini Manesh

Electronic Theses and Dissertations

The main purpose of this work is to find a physical and numerical description related to the reaction of the multilayer nano energetic material (nEM) in dense film. Energy density of nEM is much higher than the conventional energetic material; therefore, nEM finds more applications in propulsions, thermal batteries, material synthesis, nano igniters, waste disposals, and power generations. The reaction model of a multilayer nEM in a dense film of aluminum and copper oxide deposits on a composite substrate of silica/silicon is studied and solved in different stages. The two main interests in this study are propagation speed and maximum …

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