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2005

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Articles 2731 - 2760 of 3074

Full-Text Articles in Engineering

New Optimal High Efficiency Dsp-Based Digital Controller Design For Super High-Speed Permanent Magnet Synchronous Motor, Limei Zhao Jan 2005

New Optimal High Efficiency Dsp-Based Digital Controller Design For Super High-Speed Permanent Magnet Synchronous Motor, Limei Zhao

Electronic Theses and Dissertations

This dissertation investigates digital controller and switch mode power supply design for super high-speed permanent magnet synchronous motors (PMSM). The PMSMs are a key component for the miniaturic cryocooler that is currently under development at the University of Central Florida with support from NASA Kennedy Space Center and the Florida Solar Energy Center. Advanced motor design methods, control strategies, and rapid progress in semiconductor technology enables production of a highly efficient digital controller. However, there are still challenges for such super high-speed controller design because of its stability, high-speed, variable speed operation, and required efficiency over a wide speed range. …

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Infrared Thermography And High Accuracy Gps For Automated Asphalt Crack Detection, Tarek M. Abdel-Monem Jan 2005

Infrared Thermography And High Accuracy Gps For Automated Asphalt Crack Detection, Tarek M. Abdel-Monem

Electronic Theses and Dissertations

Roads are major public assets. The USA spends billions of dollars each year on road construction and maintenance. To keep these roads in a healthy condition and for better planning and allocation of maintenance budgets, knowledge of distressed locations is needed. Roads develop cracks when they are subjected to stresses that exceed their designed criteria or their materials properties. Early detection and repair of cracks has proven to be the most cost-effective strategy in limiting the damage to roads and reducing expenditures. Various methodologies of crack detection were developed and significant techniques were made in the last few years. One …

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The Effects Of Electrode Geometry On Current Pulse Caused By Electrical Discharge Over An Ultra-Fast Laser Filament, Matthew Bubelnik Jan 2005

The Effects Of Electrode Geometry On Current Pulse Caused By Electrical Discharge Over An Ultra-Fast Laser Filament, Matthew Bubelnik

Electronic Theses and Dissertations

The time-resolved electrical conductivity of a short-pulse generated plasma filament in air was studied. Close-coupled metal electrodes were used to discharge the stored energy of a high-voltage capacitor and the resulting microsecond-scale electrical discharge was measured using fast current sensors. Significant differences in the time dependence of the current were seen with the two electrode geometries used. Using sharp-tipped electrodes additional peaks in the time-resolved conductivity were seen, relative to the single peak seen with spherical electrodes. We attribute these additional features to secondary electron collisional ionization brought about by field enhancement at the tips. Additional discrepancies in the currents …

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Assessing The Impact Of University Technology Incubator Practices On Client Performance, Thomas O'Neal Jan 2005

Assessing The Impact Of University Technology Incubator Practices On Client Performance, Thomas O'Neal

Electronic Theses and Dissertations

This research is designed to distinguish and describe or explain incubator practices that affect the performance of incubator clients of university technology incubator programs. The research focuses on understanding which practices significantly contribute to increasing job creation for the firms located in university based technology incubators. An increasing number of communities are embracing economic development strategies that target the high tech sector with high wage, high value jobs as a way to diversify their economies and boost local and regional economies. New economic development strategies include the notion of a creation strategy or "growing your own" instead of relying on …

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Advances In The Opto-Mechanical Design And Alignment Of The Hehsi Imaging Spectrometer Based On A Sagnac Interferometer, Michael Stuart Schreiber Jan 2005

Advances In The Opto-Mechanical Design And Alignment Of The Hehsi Imaging Spectrometer Based On A Sagnac Interferometer, Michael Stuart Schreiber

Electronic Theses and Dissertations

The High Efficiency HyperSpectral Imager (HEHSI) is a Fourier Transform hyperspectral imager based on a Sagnac interferometer. This thesis research concentrates on the design upgrade and calibration of HEHSI from a proof of concept instrument to a prototype field instrument. Stability is enhanced by removing degrees of freedom and alignment is enhanced by providing for in-situ adjustments. The use of off the shelf components allows for reduced development time and cost constraints. HEHSI is capable of multiple configurations to accommodate sensors and optics with specialized capabilities for multiple wavelength ranges and viewing conditions. With a spectral response of 400 to …

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Or-05-6-4: Relating Human Productivity And Annoyance To Indoor Noise Criteria Systems: A Low Frequency Analysis, Erica Eileen Bowden, Lily M. Wang Jan 2005

Or-05-6-4: Relating Human Productivity And Annoyance To Indoor Noise Criteria Systems: A Low Frequency Analysis, Erica Eileen Bowden, Lily M. Wang

Durham School of Architectural Engineering and Construction: Faculty Publications

A number of indoor noise criteria systems are used to quantify the background noise in a built environment, including Noise Criteria (NC), Balanced Noise Criteria (NCB), Room Criteria (RC), Room Criteria Mark II (RC Mark II), A-weighted Equivalent Sound Pressure Level (LAeq), and others. An on-going debate exists in the acoustical community over which criterion is the most appropriate to use in the variety of ambient noise situations encountered. In an effort to quantitatively support the use of individual criterion, this project subjectively correlates these various criteria with human task performance and perception. Eleven subjects participated in a …

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A New Hybrid Diffractive Photo-Mask Technology, Jin Won Sung Jan 2005

A New Hybrid Diffractive Photo-Mask Technology, Jin Won Sung

Electronic Theses and Dissertations

In the field of photolithography for micro-chip manufacturing, the photo-mask is used to print desired patterns on a proper photo-resist on wafer. The most common type of photo-mask is binary amplitude mask made an opaque layer of chrome. The principle and potential application of hybrid photo-mask with diffractive phase element and binary amplitude is presented in this dissertation paper from both numerical modeling and experimental research. The first important application is the characterization of aberration in the stepper system using hybrid diffractive photo-mask. By utilizing multiple diffractive illumination conditions, it is possible to characterize Zernike wave front aberration coefficients up …

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Spectral Signature Modification By Application Of Infrared Frequency-Selective Surfaces, Brian Monacelli Jan 2005

Spectral Signature Modification By Application Of Infrared Frequency-Selective Surfaces, Brian Monacelli

Electronic Theses and Dissertations

It is desirable to modify the spectral signature of a surface, particularly in the infrared (IR) region of the electromagnetic spectrum. To alter the surface signature in the IR, two methods are investigated: thin film application and antenna array application. The former approach is a common and straightforward incorporation of optically-thin film coatings on the surface designated for signature modification. The latter technique requires the complex design of a periodic array of passive microantenna elements to cover the surface in order to modify its signature. This technology is known as frequency selective surface (FSS) technology and is established in the …

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Liquid Crystal Optics For Communications, Signal Processing And 3-D Microscopic Imaging, Sajjad Khan Jan 2005

Liquid Crystal Optics For Communications, Signal Processing And 3-D Microscopic Imaging, Sajjad Khan

Electronic Theses and Dissertations

This dissertation proposes, studies and experimentally demonstrates novel liquid crystal (LC) optics to solve challenging problems in RF and photonic signal processing, freespace and fiber optic communications and microscopic imaging. These include free-space optical scanners for military and optical wireless applications, variable fiber-optic attenuators for optical communications, photonic control techniques for phased array antennas and radar, and 3-D microscopic imaging. At the heart of the applications demonstrated in this thesis are LC devices that are non-pixelated and can be controlled either electrically or optically. Instead of the typical pixel-by-pixel control as is custom in LC devices, the phase profile across …

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Procedures For The Estimation Of Pavement And Bridge Preservation Costs For Fiscal Planning And Programming, Kumares C. Sinha, Samuel Labi, Marcela Rodriguez, Gabriel U. Tine, Rucci Dutta Jan 2005

Procedures For The Estimation Of Pavement And Bridge Preservation Costs For Fiscal Planning And Programming, Kumares C. Sinha, Samuel Labi, Marcela Rodriguez, Gabriel U. Tine, Rucci Dutta

JTRP Technical Reports

Facility preservation generally refers to the set of activities that are carried out to keep a facility in usable condition until the next reconstruction activity. For fiscal planning and programming, it is necessary to know the expected costs of preservation projects and how long they would last. Such information, coupled with minimum standards and facility inventory data enable estimation of overall monetary needs for bridge and pavement preservation, and would assist INDOT in undertaking appropriate programming and attendant financial planning over the long term. However, detailed engineering analyses are not possible every year because of the time and effort involved, …

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Its Strategies For Minimization Of Fine Particulates, Ahmed S. Soliman, Robert Bertram Jacko, Barry K. Partridge Jan 2005

Its Strategies For Minimization Of Fine Particulates, Ahmed S. Soliman, Robert Bertram Jacko, Barry K. Partridge

JTRP Technical Reports

The purpose of the study was to quantify the impact of traffic conditions such as free flow and congestion on local air quality. The Borman Expressway in Northwest Indiana is considered a test-bed for this research due to the high volume of class-9-truck traffic traveling on it, as well as the existing and continuing installation of the Intelligent Transportation System (ITS) to improve the traffic management along the highway stretch. An empirical Traffic-Air-Quality model (TAQ model) was developed to estimate the PM2.5 emission factors (g/mi) based solely on the measured traffic parameters such as average speed, average acceleration and truck …

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Configuration Methodology For Traffic-Responsive Plan Selection: A Global Perspective, Montasir M. Abbas, Nadeem A. Chaudhary, Geza Pesti, Anuj Sharma Jan 2005

Configuration Methodology For Traffic-Responsive Plan Selection: A Global Perspective, Montasir M. Abbas, Nadeem A. Chaudhary, Geza Pesti, Anuj Sharma

Department of Civil and Environmental Engineering: Faculty Publications

Although several studies have shown the potential great benefits of traffic-responsive plan selection (TRPS) control, time-of-day operation continues to be the primary method used to select patterns for signal control applications. This practice could be largely attributed to the minimal guidelines available on the setup of the TRPS mode. An innovative framework for TRPS system setup is provided, and guidelines for implementing TRPS in a simplified manner are shown. The guidelines, developed at Texas Transportation Institute (TTI), use a comprehensive approach that incorporates a multiobjective evolutionary algorithm and a supervised discriminant analysis. Engineers can directly implement the guidelines presented as …

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The Effect Of Post-9/ 11 Security Requirements On Aviation Higher Education And Aviation Higher Education Student Attitudes Toward The United States, Richard G. Ham, Sr. Jan 2005

The Effect Of Post-9/ 11 Security Requirements On Aviation Higher Education And Aviation Higher Education Student Attitudes Toward The United States, Richard G. Ham, Sr.

Theses and Dissertations

This study investigates the effect of security measures implemented as a result of the terrorist attacks of September 11, 2001 on aviation higher education and how the measures affected aviation higher education students' attitudes toward the United States. The underlying premise of the study is that international persistence represents the ultimate indicator of economic and cultural effect on higher education while international student attitudes provide insight into possible causes of eroding international relationships that lead to terrorism. This is a sequential mixed methods study using a qualitative interview pilot study as the foundation, followed by a quantitative survey and ending …

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Numerical Analysis Of Heat Transfer In Pulsating Turbulent Flow In A Pipe, Xuefeng Wang, Nengli Zhang Jan 2005

Numerical Analysis Of Heat Transfer In Pulsating Turbulent Flow In A Pipe, Xuefeng Wang, Nengli Zhang

Department of Mechanical and Materials Engineering: Faculty Publications

Convection heat transfer in pulsating turbulent flow with large velocity oscillating amplitudes in a pipe at constant wall temperature is numerically studied. A low-Reynolds-number (LRN) k–ε turbulent model is used in the turbulence modeling. The model analysis indicates that Womersley number is a very important parameter in the study of pulsating flow and heat transfer. Flow and heat transfer in a wide range of process parameters are investigated to reveal the velocity and temperature characteristics of the flow. The numerical calculation results show that in a pulsating turbulent flow there is an optimum Womersley number at which heat transfer is …

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Learning Games Programming With Dalek World., Bryan Duggan, Hugh Mcatamney, Fredrick Mtenzi Jan 2005

Learning Games Programming With Dalek World., Bryan Duggan, Hugh Mcatamney, Fredrick Mtenzi

Conference papers

From September 2005 the School of Computing in the DIT will offer an elective in computer games programming to final year computer science students. This paper demonstrates how students will learn games programming by developing a 3D FPS (First Person Shooter) called Dalek World. Dalek World is developed using Microsoft Visual Studio in C++ and was originally developed by the authors to learn games programming techniques themselves. In developing Dalek World, students will learn Euclidian geometry, 3D graphics programming, object orientated game design, level loading, physics, collision detection, the A* algorithm, perception and enemy AI using finite state machines.

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The Tribological Role Of Energy Efficiency Within Society, Matthew Siniawski Jan 2005

The Tribological Role Of Energy Efficiency Within Society, Matthew Siniawski

Mechanical Engineering Faculty Works

No abstract provided.

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The Effect Of Cu-Doping On The Magnetic And Transport Properties Of La₀.₇Sr₀.₃Mno₃, M. S. Kim, Jinbo Yang, Qingsheng Cai, X.-D. Zhou, William B. Yelon, Paul Ernest Parris, William Joseph James Jan 2005

The Effect Of Cu-Doping On The Magnetic And Transport Properties Of La₀.₇Sr₀.₃Mno₃, M. S. Kim, Jinbo Yang, Qingsheng Cai, X.-D. Zhou, William B. Yelon, Paul Ernest Parris, William Joseph James

Physics Faculty Research & Creative Works

The effects of Cu-doping on the structural, magnetic, and transport properties of La0.7Sr0.3Mn1xCuxO3 (0<=x<=0.20) have been studied using neutron diffraction, magnetization, and magnetoresistance (MR) measurements. All samples show the rhombohedral structure with the R[overline 3]c space-group from 10 K to room temperature (RT). Neutron diffraction data suggest that some of the Cu ions have a Cu3+ state in these compounds. The substitution of Mn by Cu affects the MnO bond length and Mn-O-Mn bond angle resulting from the minimization of the distortion of the MnO6 octahedron. Resistivity measurements show that a metal to insulator transition occurs for the x>=0.15 samples. The x=0.15 sample shows the highest MR([approximate]80%), which might result from the co-existence of Cu3-Cu2+ and the dilution effect of Cu-doping on the double exchange interaction

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Haptic-Based Dental Procedure Training Simulator, Cristian Luciano Jan 2005

Haptic-Based Dental Procedure Training Simulator, Cristian Luciano

Link Foundation Modeling, Simulation and Training Fellowship Reports

Since the beginning of the last century, simulators have been widely used in military and aviation. Recently, the use of simulation in medicine and dentistry has brought the attention of the research community, looking for efficient ways to increase patient's safety by improving surgeon's and dentist's skills. Traditionally, plastic mannequins and cadavers were used to train medical and dental students. However, the lack of details and differences on material properties (in the case of mannequins), and high costs and ethical issues (in the case of cadavers)- supported by the lately improvements of virtual reality, haptics and robotics - have increased …

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Creating Geo-Specific Road Databases For A Real-Time Interactive Driving Simulator, Dahai Guo Jan 2005

Creating Geo-Specific Road Databases For A Real-Time Interactive Driving Simulator, Dahai Guo

Link Foundation Modeling, Simulation and Training Fellowship Reports

Geo-specific road database development is important to a driving simulation system and a very labor intensive process. Road databases for driving simulation need high resolution and accuracy. Even though commercial software is available on the market, a lot of manual work still has to be done when the road crosssectional profile is not uniform. This research deals with geo-specific road databases development, especially for roads with non-uniform cross sections. In this research, the United States Geographical Survey (USGS) road information is used with aerial photos to accurately extract road boundaries, using image segmentation and data compression techniques. Image segmentation plays …

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Performance Enhancement Of The Wirewalker Wave-Powered Profiler, Jonathan Pompa Jan 2005

Performance Enhancement Of The Wirewalker Wave-Powered Profiler, Jonathan Pompa

Link Foundation Ocean Engineering and Instrumentation Fellowship Reports

The Wire-Walker is a wave-powered vertical profiler made for carrying oceanographic instruments. It cycles continuously through the depth range set by the user, providing a traveling platform for sensors. To achieve high data resolution in time varying environments, the Wire-Walker was redesigned from its original configuration for higher profiling speed. Improvements were made to the WireWalker profiler by using a numerical simulation of the system dynamics. Each physical parameter was varied in the model to find its effect on the profiling speed. Using the guidelines from the modeling experiment, a new WireWalker was constructed and tested in the ocean. The …

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Electromechanical Characterization Of Poly(Dimethyl Siloxane) Based Electroactive Polymers, Wrutu Deepak Parulkar Jan 2005

Electromechanical Characterization Of Poly(Dimethyl Siloxane) Based Electroactive Polymers, Wrutu Deepak Parulkar

Theses and Dissertations

The main objectives of this thesis are 1) to evaluate the effect of cross-linking polar cyano phenyl (CN) groups on poly (dimethyl siloxane) (PDMS) and 2) to characterize the electromechanical properties of the resulting CN-PDMS blend as an electroactive actuator. Materials responding to an external stimulus are referred to as electroactive materials. There are several phenomena, which govern the mechanism in these materials, such as piezoelectricity, Maxwell's effect, ferroelectricity, electrostriction to name a few. These electroactive materials can be employed in several applications such as biomedical devices, robots, MEMs, aerospace vehicles, where the application is governed by the specific mechanism. …

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Making Sense Of Nanocrystal Lattice Fringes, P. Fraundorf, Wentao Qin, Peter Moeck, Eric Mandell Jan 2005

Making Sense Of Nanocrystal Lattice Fringes, P. Fraundorf, Wentao Qin, Peter Moeck, Eric Mandell

Physics Faculty Publications and Presentations

The orientation dependence of thin-crystal lattice fringes can be gracefully quantified using fringe-visibility maps, a direct-space analog of Kikuchi maps [Nishikawa and Kikuchi, Nature (London) 121, 1019 (1928)]. As in navigation of reciprocal space with the aid of Kikuchi lines, fringe-visibility maps facilitate acquisition of crystallographic information from lattice images. In particular, these maps can help researchers to determine the three-dimensional lattice of individual nanocrystals, to 'fringe-fingerprint' collections of randomly oriented particles, and to measure local specimen thickness with only a modest tilt. Since the number of fringes in an image increases with maximum spatial-frequency squared, these strategies (with help …

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Large Scale Visualization Of Pulsed Vortex Generator Jets, Kenneth Jay Moore Jr. Jan 2005

Large Scale Visualization Of Pulsed Vortex Generator Jets, Kenneth Jay Moore Jr.

Browse all Theses and Dissertations

The use of small jets of air has proven to be an effective means of flow control on low Reynolds number turbine blades. Pulsing of these jets has also shown benefits in reducing the amount of air needed to achieve the same level of flow control. An experiment using Hot Wire Anemometry and Particle Image Velocimetry (PIV) has been used to investigate how these pulsed jets interact with the boundary layer to help keep the flow attached. A 25x scaled jet in a flat plate has been utilized. The 25.4 mm diameter jet has a pitch angle of 30° and …

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Nano-Coatings On Carbon Structures For Interfacial Modification, Rajasekhar Venkata Pulikollu Jan 2005

Nano-Coatings On Carbon Structures For Interfacial Modification, Rajasekhar Venkata Pulikollu

Browse all Theses and Dissertations

Surface modification of materials is a rapidly growing field as structures become smaller, more integrated and complex. It opens up the possibility of combining the optimum bulk properties of a material with optimized surface properties such as enhanced bonding, corrosion resistance, reactivity, stress transfer, and thermal, optical or electrical behavior. Therefore, surface functionalization or modification can be an enabling step in a wide variety of modern applications. In this dissertation several surface modification approaches on carbon foam and carbon nano-fibers will be discussed. These are recently developed sp 2 graphitic carbon based structures that have significant potential in aerospace, automotive …

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Pattern Recognition Via Machine Learning With Genetic Decision-Programming, Carl C. Hoff Jan 2005

Pattern Recognition Via Machine Learning With Genetic Decision-Programming, Carl C. Hoff

Browse all Theses and Dissertations

In the intersection of pattern recognition, machine learning, and evolutionary computation is a new search technique by which computers might program themselves. That technique is called genetic decision-programming. A computer can gain the ability to distinguish among the things that it needs to recognize by using genetic decision-programming for pattern discovery and concept learning. Those patterns and concepts can be easily encoded in the spines of a decision program (tree or diagram). A spine consists of two parts: (1) the test-outcome pairs along a path from the program's root to any of its leaves and (2) the conclusion in that …

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Bs News Jan 2005

Bs News

Building Services Engineering

No abstract provided.

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Investigation Of Surface States And Device Surface Charging In Nitride Materials Using Scanning Kelvin Probe Microscopy, Mohammed Shahriar Sabuktagin Jan 2005

Investigation Of Surface States And Device Surface Charging In Nitride Materials Using Scanning Kelvin Probe Microscopy, Mohammed Shahriar Sabuktagin

Theses and Dissertations

In this work Scanning Kelvin Probe Microscopy (SKPM) was used to characterize surface states and device surface charging in nitride materials. Samples grown by Molecular Beam Epitaxy (MBE), Metal Organic Chemical Vapor Deposition (MOCVD) and Hydride Vapor Phase Epitaxy (HVPE) typically show a high surface band bending of about 1 eV. In an n-type sample with 3X1017 cm-3 carrier concentration, 1 eV upward band bending corresponds to 1.7X1012 cm-2 trapped charge density in the surface states. Under continuous ultraviolet (UV) illumination up to 0.6 eV surface photo voltage effect could be observed in some samples, which further indicates that surface …

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Real Time Frequency Analysis Of Signals From Lasso Catheter For Radiofrequency Ablation During Atrial Fibrillation, Prashant Yadav Jan 2005

Real Time Frequency Analysis Of Signals From Lasso Catheter For Radiofrequency Ablation During Atrial Fibrillation, Prashant Yadav

Theses and Dissertations

Real time spectrum analysis of signals obtained through lasso catheter during radiofrequency ablation of pulmonary vein was performed to determine the channel with dominant frequency. Threshold algorithm was used for signals which could be classified as type I and type II AF. Type III AF Signals which were highly fractionated or differentiated were evaluated for frequency content by performing Fast Fourier Transform. Data from Seven patients was collected and an episode of 180 ± 40 seconds was recorded and analyzed for each pulmonary vein that showed electrical activation. Frequency spectra for one second segment of signal for each channel were …

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Heat Transfer Model For The Ignition Of Metal Powder On A Heated Filament, Trent Stanton Ward Jan 2005

Heat Transfer Model For The Ignition Of Metal Powder On A Heated Filament, Trent Stanton Ward

Theses

The thermal processes leading to ignition of metal powders in environments that experience rapid temperature changes are currently poorly understood. In this research, a methodology for studying and quantification of such processes is developed. In the experimental case study, the ignition temperature of Mg powder coated on the surface of an electrically heated filament is detected optically at different heating rates. To interpret the results, a heat transfer model has been developed for a multilayer powder coating on top of an electrically heated filament. The coating is modeled using a hexagonal close packed geometry and the heat transfer equations are …

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Microwave Processing Of Fiber Reinforced Composites (Optimization Of Glass Reinforced Epoxy Curing Process), Mohamed Osama Ali Jan 2005

Microwave Processing Of Fiber Reinforced Composites (Optimization Of Glass Reinforced Epoxy Curing Process), Mohamed Osama Ali

Theses

Microwave curing of polymer matrix composites has proven to be an attractive substitute for conventional thermal curing. Industrial applications are currently developed including telecommunications, aerospace, food industry, enhancement concrete setting, composites manufacturing, and many others. Many universities and research centers around the globe are endeavoring to make use of this technology to the most. Common research objectives include homogeneity of the cure, the acceleration of cure kinetics, cure reaction mechanism, and enhancement of mechanical properties. In order to efficiently utilize this form of energy, precise control over power, temperature, and time were applied to achieve set goals: reduce cure time …

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