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2011

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Articles 4561 - 4590 of 5801

Full-Text Articles in Engineering

Spatio-Temporal Negotiation Protocols, Yi Luo Jan 2011

Spatio-Temporal Negotiation Protocols, Yi Luo

Electronic Theses and Dissertations

Canonical problems are simplified representations of a class of real world problems. They allow researchers to compare algorithms in a standard setting which captures the most important challenges of the real world problems being modeled. In this dissertation, we focus on negotiating a collaboration in space and time, a problem with many important real world applications. Although technically a multi-issue negotiation, we show that the problem can not be represented in a satisfactory manner by previous models. We propose the "Children in the Rectangular Forest" (CRF) model as a possible canonical problem for negotiating spatio-temporal collaboration. In the CRF problem, …

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Cfd Analysis Of A Uni-Directional Impulse Turbine For Wave Energy Conversion, Carlos Alberto Velez Jan 2011

Cfd Analysis Of A Uni-Directional Impulse Turbine For Wave Energy Conversion, Carlos Alberto Velez

Electronic Theses and Dissertations

Ocean energy research has grown in popularity in the past decade and has produced various designs for wave energy extraction. This thesis focuses on the performance analysis of a uni-directional impulse turbine for wave energy conversion. Uni-directional impulse turbines can produce uni-directional rotation in bi-directional flow, which makes it ideal for wave energy extraction as the motion of ocean waves are inherently bi-directional. This impulse turbine is currently in use in four of the world’s Oscillating Wave Columns (OWC). Current research to date has documented the performance of the turbine but little research has been completed to understand the flow …

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Reliability Study Of Ingap/Gaas Heterojunction Bipolar Transistor Mmic Technology By Characterization, Modeling And Simulation, Xiang Liu Jan 2011

Reliability Study Of Ingap/Gaas Heterojunction Bipolar Transistor Mmic Technology By Characterization, Modeling And Simulation, Xiang Liu

Electronic Theses and Dissertations

Recent years have shown real advances of microwave monolithic integrated circuits (MMICs) for millimeter-wave frequency systems, such as wireless communication, advanced imaging, remote sensing and automotive radar systems, as MMICs can provide the size, weight and performance required for these systems. Traditionally, GaAs pseudomorphic high electron mobility transistor (pHEMT) or InP based MMIC technology has dominated in millimeter-wave frequency applications because of their high fT and fmax as well as their superior noise performance. But these technologies are very expensive. Thus, for low cost and high performance applications, InGaP/GaAs heterojunction bipolar transistors (HBTs) are quickly becoming the preferred technology to …

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Labeled Sampling Consensus A Novel Algorithm For Robustly Fitting Multiple Structures Using Compressed Sampling, Carl J. Messina Jan 2011

Labeled Sampling Consensus A Novel Algorithm For Robustly Fitting Multiple Structures Using Compressed Sampling, Carl J. Messina

Electronic Theses and Dissertations

The ability to robustly fit structures in datasets that contain outliers is a very important task in Image Processing, Pattern Recognition and Computer Vision. Random Sampling Consensus or RANSAC is a very popular method for this task, due to its ability to handle over 50% outliers. The problem with RANSAC is that it is only capable of finding a single structure. Therefore, if a dataset contains multiple structures, they must be found sequentially by finding the best fit, removing the points, and repeating the process. However, removing incorrect points from the dataset could prove disastrous. This thesis offers a novel …

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Data-True Characterization Of Neuronal Models, Jose Suarez Jan 2011

Data-True Characterization Of Neuronal Models, Jose Suarez

Electronic Theses and Dissertations

In this thesis, a weighted least squares approach is initially presented to estimate the parameters of an adaptive quadratic neuronal model. By casting the discontinuities in the state variables at the spiking instants as an impulse train driving the system dynamics, the neuronal output is represented as a linearly parameterized model that depends on filtered versions of the input current and the output voltage at the cell membrane. A prediction errorbased weighted least squares method is formulated for the model. This method allows for rapid estimation of model parameters under a persistently exciting input current injection. Simulation results show the …

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Impurity And Interdiffusion In The Magnesium-Aluminum System, Sarah Tiffany Brennan Jan 2011

Impurity And Interdiffusion In The Magnesium-Aluminum System, Sarah Tiffany Brennan

Electronic Theses and Dissertations

Magnesium alloys offer a base of lightweight engineering materials for electronic, military and transportation applications where weight reduction is crucial for higher efficiency. Understanding fundamental diffusion behavior in Mg alloys elicits better materials properties through the optimization of processing techniques and heat treatments, whose material responses are affected by diffusion. The main objective of this study is to provide a clear, comprehensive description of the diffusion behavior in the technically important magnesium-aluminum binary metallic system. In this study, diffusion in the Mg-Al system was observed through solid diffusion couples and thin film specimens in the temperature range of 673-523K. The …

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Robustness Analysis For Turbomachinery Stall Flutter, Md Moinul Forhad Jan 2011

Robustness Analysis For Turbomachinery Stall Flutter, Md Moinul Forhad

Electronic Theses and Dissertations

Flutter is an aeroelastic instability phenomenon that can result either in serious damage or complete destruction of a gas turbine blade structure due to high cycle fatigue. Although 90% of potential high cycle fatigue occurrences are uncovered during engine development, the remaining 10% stand for one third of the total engine development costs. Field experience has shown that during the last decades as much as 46% of fighter aircrafts were not mission-capable in certain periods due to high cycle fatigue related mishaps. To assure a reliable and safe operation, potential for blade flutter must be eliminated from the turbomachinery stages. …

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High Linearity 5.8 Ghz Power Amplifier With An Internal Linearizer, Yiheng Wang Jan 2011

High Linearity 5.8 Ghz Power Amplifier With An Internal Linearizer, Yiheng Wang

Electronic Theses and Dissertations

A 5.8 GHz RF Power Amplifier (PA) is designed and fabricated in this work, which has very high linearity through a built-in linearizer. The PA is designed, post-layout simulated by Agilent Advanced Design System (ADS) software and fabricated by Win-Semiconductors 0.15µm pHEMT process technology. The post-layout simulation results illustrate the power amplifier can obtained an output power of 23.98 dBm, a power gain of 32.28 dB and a power added efficiency (PAE) of 29% at saturation region, the 3rd intermodulation distortion (IMD3) of -37.7 dBc at 0 dBm input power is attained when operation frequency is 5.8 GHz. We finally …

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Models To Estimate Arrival Counts And Staffing Requirements In Nonstationary Queueing Systems Applied To Long Distance Road Races, Lindon P. Fairweather Jan 2011

Models To Estimate Arrival Counts And Staffing Requirements In Nonstationary Queueing Systems Applied To Long Distance Road Races, Lindon P. Fairweather

Electronic Theses and Dissertations

We examine the problem of staffing refreshment stations at a long distance road race. A race is modeled as a mixed queueing network in which the required number of servers at each service station has to be estimated. Two models to represent the progress of runners along a long distance road race course are developed. One model is a single-class model that allows a road race manager to staff service stations assuming the runners are identical to those in some historical dataset. Another model is a multi-class simulation model that allows a road race manager to simulate a race of …

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2008 Emissions Inventory Of Central Florida, Jessica Leigh Ross Jan 2011

2008 Emissions Inventory Of Central Florida, Jessica Leigh Ross

Electronic Theses and Dissertations

An emissions inventory of VOCs, NOx, and CO2 was conducted for three central Florida counties – Orange, Seminole, and Osceola (OSO) – for calendar year 2008. The inventory utilized three programs: MOBILE6, NONROAD2005, and EDMS (Emissions and Dispersion Modeling System) to model on‐road mobile, non‐road mobile, and airport emissions, respectively. Remaining point and area source data was estimated from the Florida Department of Environmental Protection (FDEP) and the U.S. Environmental Protection Agency’s (U.S. EPA) 2008 emissions inventory. The previous OSO emissions inventory was done in 2002 and in the six years between inventories, there have been changes in population, commerce, …

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Rain Rate Retrieval Algorithm For Aquarius/Sac-D Microwave Radiometer, Rosa Ana Menzerotolo Jan 2011

Rain Rate Retrieval Algorithm For Aquarius/Sac-D Microwave Radiometer, Rosa Ana Menzerotolo

Electronic Theses and Dissertations

Microwave radiometers are used to measure blackbody microwave emissions emitted by natural targets. Radiative transfer theory provides a well founded physical relationship between the atmosphere and surface geophysical parameters and the brightness temperature measured by these radiometers. The atmospheric brightness temperature is proportional to the integral of the microwave absorption of water vapor, oxygen, and liquid water between the top of the atmosphere and the surface. Inverse radiative transfer models use to retrieve the water vapor, cloud liquid and oxygen content in the atmosphere are very well known; however, the retrieval of rain rate in the atmosphere is still a …

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Field Implementation Of Polyacrylamide For Runoff From Construction Sites, Rafiqul Islam Chowdhury Jan 2011

Field Implementation Of Polyacrylamide For Runoff From Construction Sites, Rafiqul Islam Chowdhury

Electronic Theses and Dissertations

Polyacrylamide (PAM) is often used a part of a treatment train for the treatment of stormwater to reduce its turbidity. This study investigated the application of PAM within various treatment systems for a construction site environment. The general concept is to introduce hydraulic principles when placing PAM blocks within an open channel in order to yield high mixing energies leading to high turbidity removal efficiency. The first part of the study observed energy variation using a hydraulic flume for three dissimilar configurations. The flume was ultimately used to determine which configuration would be most beneficial when transposed into field-scale conditions. …

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Effect Of Acetic Or Citric Acid Ultrafiltration Recycle Streams On Coagulation Processes, Christopher C. Boyd Jan 2011

Effect Of Acetic Or Citric Acid Ultrafiltration Recycle Streams On Coagulation Processes, Christopher C. Boyd

Electronic Theses and Dissertations

Integrating ultrafiltration (UF) membranes in lieu of traditional media filters within conventional surface water coagulation-flocculation-sedimentation processes is growing in popularity. UF systems are able to produce low turbidity filtered water that meets newer drinking water standards. For typical drinking water applications, UF membranes require periodic chemically enhanced backwashes (CEBs) to maintain production; and citric acid is a common chemical used for this purpose. Problems may arise when the backwash recycle stream from a citric acid CEB is blended with raw water entering the coagulation basin, a common practice for conventional surface water plants. Citric acid is a chelating agent capable …

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Optimal Detour Planning Around Blocked Construction Zones, Mutasem Jardaneh Jan 2011

Optimal Detour Planning Around Blocked Construction Zones, Mutasem Jardaneh

Electronic Theses and Dissertations

Construction zones are traffic way areas where construction, maintenance or utility work is identified by warning signs, signals and indicators, including those on transport devices that mark the beginning and end of construction zones. Construction zones are among the most dangerous work areas, with workers facing workplace safety challenges that often lead to catastrophic injuries or fatalities. In addition, daily commuters are also impacted by construction zone detours that affect their safety and daily commute time. These problems represent major challenges to construction planners as they are required to plan vehicle routes around construction zones in such a way that …

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Modeling, Design And Fabrication Of Orthogonal And Psuedo-Orthogonal Frequency Coded Saw Wireless Spread Spectrum Rfid Sensor Tags, Nancy Saldanha Jan 2011

Modeling, Design And Fabrication Of Orthogonal And Psuedo-Orthogonal Frequency Coded Saw Wireless Spread Spectrum Rfid Sensor Tags, Nancy Saldanha

Electronic Theses and Dissertations

Surface acoustic wave (SAW) sensors offer a wireless, passive sensor solution for use in numerous environments where wired sensing can be expensive and infeasible. Single carrier frequency SAW sensor embodiments such as delay lines, and resonators have been used in single sensor environments where sensor identification is not a necessity. The orthogonal frequency coded (OFC) SAW sensor tag embodiment developed at UCF uses a spread spectrum approach that allows interrogation in a multi-sensor environment and provides simultaneous sensing and sensor identi- fication. The SAW device is encoded via proper design of multiple Bragg reflectors at differing frequencies. To enable accurate …

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Incremental Lifecycle Validation Of Knowledge-Based Systems Through Commonkads, Feras Batarseh Jan 2011

Incremental Lifecycle Validation Of Knowledge-Based Systems Through Commonkads, Feras Batarseh

Electronic Theses and Dissertations

This dissertation introduces a novel validation method for knowledge-based systems (KBS). Validation is an essential phase in the development lifecycle of knowledge-based systems. Validation ensures that the system is valid, reliable and that it reflects the knowledge of the expert and meets the specifications. Although many validation methods have been introduced for knowledge-based systems, there is still a need for an incremental validation method based on a lifecycle model. Lifecycle models provide a general framework for the developer and a mapping technique from the system into the validation process. They support reusability, modularity and offer guidelines for knowledge engineers to …

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Super-Adiabatic Combustion In Porous Media With Catalytic Enhancement For Thermoelectric Power Conversion, Kyle Thomas Mueller Jan 2011

Super-Adiabatic Combustion In Porous Media With Catalytic Enhancement For Thermoelectric Power Conversion, Kyle Thomas Mueller

Electronic Theses and Dissertations

The combustion of ultra-lean fuel to air mixtures provides an efficient way to convert the chemical energy of hydrocarbons into useful power. Conventional burning techniques of a mixture have defined flammability limits beyond which a flame cannot self-propagate due to heat losses. Matrix stabilized porous medium combustion is an advanced technique in which a solid porous matrix within the combustion chamber accumulates heat from the hot gaseous products and preheats incoming reactants. This heat recirculation extends the standard flammability limits and allows the burning of ultra-lean fuel mixtures, conserving energy resources, or the burning of gases of low calorific value, …

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A Novel Experimental Approach Using A Reconfigurable Test Setup For Complex Nonlinear Dynamic Systems, Aaron Rank Jan 2011

A Novel Experimental Approach Using A Reconfigurable Test Setup For Complex Nonlinear Dynamic Systems, Aaron Rank

Electronic Theses and Dissertations

Experimental nonlinear dynamics is an important area of study in the modern engineering field, with engineering applications in structural dynamics, structural control, and structural health monitoring. As a result, the discipline has experienced a great influx of research efforts to develop a versatile and reliable experimental methodology. A technical challenge in many experimental studies is the procurement of a device that exhibits the desired nonlinear behavior. As a result, many researchers have longed for a versatile, but accurate, testing methodology that has complete freedom to simulate a wide range of nonlinearities and stochastic behaviors. The objective of this study is …

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Class F And Inverse Class F Power Amplifier Subject To Electrical Stress Effect, Giji Skaria Jan 2011

Class F And Inverse Class F Power Amplifier Subject To Electrical Stress Effect, Giji Skaria

Electronic Theses and Dissertations

This study investigated the Class F and inverse Class F RF power amplifier operating at 5.8 GHz. The major challenging issue in design and implementation of CMOS power transistor is the breakdown voltage especially in sub-micron CMOS technologies. In order to eliminate this problem a Cascode topologies were implemented to reduce the Drain-toSource voltage (stress). A Cascode Class F & Inverse Class F RF power amplifier were designed, and optimized in order to improve efficiency and reliability using 0.18µm CMOS technology process. A 50% decrease in the stress has been achieved in the Cascode class-F and Inverse class F amplifiers. …

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Measuring And Improving Internet Video Quality Of Experience, Mukundan Venkataraman Iyengar Jan 2011

Measuring And Improving Internet Video Quality Of Experience, Mukundan Venkataraman Iyengar

Electronic Theses and Dissertations

Streaming multimedia content over the IP-network is poised to be the dominant Internet traffic for the coming decade, predicted to account for more than 91% of all consumer traffic in the coming years. Streaming multimedia content ranges from Internet television (IPTV), video on demand (VoD), peer-to-peer streaming, and 3D television over IP to name a few. Widespread acceptance, growth, and subscriber retention are contingent upon network providers assuring superior Quality of Experience (QoE) on top of todays Internet. This work presents the first empirical understanding of Internet’s video-QoE capabilities, and tools and protocols to efficiently infer and improve them. To …

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Heat Transfer Study Of A Triple Row Impingement Channel At Large Impingement Heights, Roberto Claretti Jan 2011

Heat Transfer Study Of A Triple Row Impingement Channel At Large Impingement Heights, Roberto Claretti

HIM 1990-2015

Advanced cooling techniques are required to increase the Brayton cycle temperature ratio necessary for the increase of the overall cycle's efficiency. Current turbine components are cooled with an array of internal cooling channels in the midchord section of the blade, pin fin arrays at the trailing edge and impingement channels in the leading edge. Impingement channels provide the designer with high convective coefficients on the target surface. Increasing the heat transfer coefficient of these channels has been a subject of research for the past 20 years. In the current study, a triple row impingement channel is studied with a jet …

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Effect Of Rib Aspect Ratio On Heat Transfer And Friction In Rectangular Channels, Lucky Vo Tran Jan 2011

Effect Of Rib Aspect Ratio On Heat Transfer And Friction In Rectangular Channels, Lucky Vo Tran

HIM 1990-2015

The heat transfer and friction augmentation in the fully developed portion of a 2:1 aspect ratio rectangular channel with orthogonal ribs at channel Reynolds numbers of 20,000, 30,000, and 40,000 is studied both experimentally and computationally. Ribs are applied to the two opposite wide walls. The rib aspect ratio is varied systematically at 1, 3, and 5, with a constant rib height and constant rib pitch (rib-pitch-to-rib-height ratio of 10). The purpose of the study is to extend the knowledge of the performance of rectangular channels with ribs to include high aspect ratio ribs. The experimental investigation is performed using …

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Study Of Esd Effects On Rf Power Amplifiers, Raju, Divya Narasimha Jan 2011

Study Of Esd Effects On Rf Power Amplifiers, Raju, Divya Narasimha

Electronic Theses and Dissertations

Today, ESD is a major consideration in the design and manufacture of ICs. ESD problems are increasing in the electronics industry because of the increasing trend toward higher speed and smaller device sizes. There is growing interest in knowing the effects of ESD protection circuit on the performance of semiconductor integrated circuits (ICs) because of the impact it has on core RF circuit performance. This study investigated the impact of ESD protection circuit on RF Power amplifiers. Even though ESD protection for digital circuits has been known for a while, RF-ESD is a challenge. From a thorough literature search on …

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Encapsulated Nanostructured Phase Change Materials For Thermal Management, Yan Hong Jan 2011

Encapsulated Nanostructured Phase Change Materials For Thermal Management, Yan Hong

Electronic Theses and Dissertations

A major challenge of developing faster and smaller microelectronic devices is that high flux of heat needs to be removed efficiently to prevent overheating of devices. The conventional way of heat removal using liquid reaches a limit due to low thermal conductivity and limited heat capacity of fluids. Adding solid nanoparticles into fluids has been proposed as a way to enhance thermal conductivity of fluids, but recent results show inconclusive anomalous enhancements in thermal conductivity. A possible way to improve heat transfer is to increase the heat capacity of liquid by adding phase change nanoparticles with large latent heat of …

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Statistical Analysis When The Data Is An Image: Eliciting Student Thinking About Sampling And Variability, Tamara J. Moore, Margret Hjalmarson, Robert Delmas Jan 2011

Statistical Analysis When The Data Is An Image: Eliciting Student Thinking About Sampling And Variability, Tamara J. Moore, Margret Hjalmarson, Robert Delmas

School of Engineering Education Faculty Publications

Within statistics education, there is a growing interest in understanding students' application of understanding about variability and sampling given the relative lack of research in either area (Shaughnessy, 2007). The task examined in this paper elicited students' knowledge of these concepts within a small-group problem solving task completed by teams of first-year engineering students. In the Nanoroughness task, teams of students designed a procedure for quantifying the roughness of a material surface using digital images generated by atomic force microscopy. The procedure required students to apply statistical methods in order to aggregate the data. The focus of this article is …

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Real-Time Beamforming Using High-Speed Fpgas At The Allen Telescope Array, William C. Barott, Oren Milgrome, Melvyn Wright, David Macmahon, Tom Kilsdonk, Peter Backus, Matt Dexter Jan 2011

Real-Time Beamforming Using High-Speed Fpgas At The Allen Telescope Array, William C. Barott, Oren Milgrome, Melvyn Wright, David Macmahon, Tom Kilsdonk, Peter Backus, Matt Dexter

Department of Electrical Engineering and Computer Science - Daytona Beach

The Allen Telescope Array (ATA) at the Hat Creek Radio Observatory (HCRO) is a wide‐field panchromatic radio telescope currently consisting of 42 offset‐Gregorian antennas each with a 6 m aperture, with plans to expand the array to 350 antennas. Through unique back‐end hardware, the ATA performs real‐time wideband beamforming with independent subarray capabilities and customizable beam shaping. The beamformers enable science observations requiring the full gain of the array, time domain (nonintegrated) output, and interference excision or orthogonal beamsets. In this paper we report on the design of this beamformer, including architecture and experimental results. Furthermore, we address some practical …

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An Investigation On Fast And Frugal Model For New Project Screening, Antonie J. Jetter, Fatima M. Albar Jan 2011

An Investigation On Fast And Frugal Model For New Project Screening, Antonie J. Jetter, Fatima M. Albar

Engineering and Technology Management Faculty Publications and Presentations

Research in psychology is increasingly interested in decision-makers' use of heuristics or rules of thumb because they have accuracies close to more complex decision rules and seem particularly useful in difficult decision-making contexts when uncertainty is high and speed is of the essence. One particularly difficult decision setting is the fuzzy front-end of new product development because a large number of product ideas need to be screened to identify the few that should be developed further. This process is currently poorly supported through decision tools and mainly occurs on the basis of managerial “gut-feel”. This study explores managerial “gut-feel” by …

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Density Determination Of Tristructural-Isotropic Nuclear Fuel Using Multiple Projection X-Ray Radiography, Frank Angelo Strantz Jan 2011

Density Determination Of Tristructural-Isotropic Nuclear Fuel Using Multiple Projection X-Ray Radiography, Frank Angelo Strantz

Masters Theses

"Effective methods of enhancing the safety and efficiency of the nuclear power industry embolden its perception and economic viability. Fuel reliability is an essential component of the prosperity of next generation high temperature reactors; as such, an equally dependable quality control method is mandatory. Tristructural-isotropic (TRISO) fuel, the fuel developed for use in these reactors, utilizes density measurement of coating layers as a standard for quality control. Common methods of measuring density, such as sink-float and ceramography are destructive, and as such generate radioactive waste, take a relatively long time to prepare samples, rely on a low sampling rate to …

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Hardened Concrete Properties And Durability Assessment Of High Volume Fly Ash Concrete, Kyle Marie Marlay Jan 2011

Hardened Concrete Properties And Durability Assessment Of High Volume Fly Ash Concrete, Kyle Marie Marlay

Masters Theses

"Concrete is produced more than any other material in the world. Sustainable construction is extremely important in today's industry and fly ash is the leading material for sustainable concrete design. The addition of fly ash improves many fresh and hardened concrete properties. However, the slow hydration process associated with fly ash makes the use of the material in large amounts undesirable in conventional construction. This study evaluated the hardened concrete and durability performance of several high-volume fly ash (HVFA) concrete mixes. The various HVFA concrete mixes evaluated within this study consisted of 70 percent replacement of portland cement by weight …

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Hall-Effect Thruster Surface Properties Investigation, David George Zidar Jan 2011

Hall-Effect Thruster Surface Properties Investigation, David George Zidar

Masters Theses

"Surface properties of Hall-effect thruster channel walls play an important role in the performance and lifetime of the device. Physical models of near-wall effects are beginning to be incorporated into thruster simulations, and these models must account for evolution of channel surface properties due to thruster operation. Results from this study show differences in boron nitride channel surface properties from beginning-of-life and after 100's of hours of operation. Two worn thruster channels of different boron nitride grades are compared with their corresponding pristine and shadow-shielded samples. Pristine HP grade boron nitride surface roughness is 9000±700 Å, while the worn sample …

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