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Articles 2401 - 2430 of 4566

Full-Text Articles in Engineering

Effects Of Flight Factors On Pilot Performance, Workload, And Stress At Final Approach To Landing Phase Of Flight, Kyongsun Lee Jan 2010

Effects Of Flight Factors On Pilot Performance, Workload, And Stress At Final Approach To Landing Phase Of Flight, Kyongsun Lee

Electronic Theses and Dissertations

Since human errors are one of the major causes of flight accidents, the design and operation of the modern aircraft system deals with them seriously. Particularly, the pilot workload on aviation causes human errors. Whenever new procedures are introduced and operated, the aircraft capabilities have been checked in every aspect. However, there has been little study on the impact of the new procedures such as LDLP, SCDA, SATS, and Steep Angle approach on the pilot performance, workload, and stress. In this study, different methods have been tried to understand the relationship between new procedures and the pilots in terms of …

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Phoneme-Based Video Indexing Using Phonetic Disparity Search, Carlos Leon Barth Jan 2010

Phoneme-Based Video Indexing Using Phonetic Disparity Search, Carlos Leon Barth

Electronic Theses and Dissertations

This dissertation presents and evaluates a method to the video indexing problem by investigating a categorization method that transcribes audio content through Automatic Speech Recognition (ASR) combined with Dynamic Contextualization (DC), Phonetic Disparity Search (PDS) and Metaphone indexation. The suggested approach applies genome pattern matching algorithms with computational summarization to build a database infrastructure that provides an indexed summary of the original audio content. PDS complements the contextual phoneme indexing approach by optimizing topic seek performance and accuracy in large video content structures. A prototype was established to translate news broadcast video into text and phonemes automatically by using ASR …

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Modeling And Simulation Of Soft Bodies, Jaruwan Mesit Jan 2010

Modeling And Simulation Of Soft Bodies, Jaruwan Mesit

Electronic Theses and Dissertations

As graphics and simulations become more realistic, techniques for approximating soft body objects, that is, non-solid objects such as liquids, gases, and cloth, are becoming increasingly common. The proposed generalized soft body method encompasses some specific cases of other existing models enabling simulation of a variety of soft body materials by parameter adjustment. This research presents a general method of soft body model and simulation in which parameters for body control, surface deformation, volume control, and gravitation, can be adjusted to simulate different types of soft bodies. In this method, the soft body mesh structure maintains configuration among surface points …

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Power Metal-Oxide-Semiconductor Field-Effect Transistor With Strained Silicon And Silicon Germanium Channel, Shan Sun Jan 2010

Power Metal-Oxide-Semiconductor Field-Effect Transistor With Strained Silicon And Silicon Germanium Channel, Shan Sun

Electronic Theses and Dissertations

With the development of modern electronics, the demand for high quality power supplies has become more urgent than ever. For power MOSFETs, maintaining the trend of reducing on-state resistance (conduction loss) without sacrificing switching performance is a severe challenge. In this work, our research is focused on implementing strained silicon and silicon germanium in power MOFETs to enhance carrier mobility, thus achieving the goal of reducing specific on-state resistance. We propose an N-channel super-lattice trench MOSFET, a P-channel sidewall channel trench MOSFET and P-Channel LDMOS with strained Si/SiGe channels. A set of fabrication processes highly compatible with conventional Si technology …

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The Next Generation Botnet Attacks And Defenses, Ping Wang Jan 2010

The Next Generation Botnet Attacks And Defenses, Ping Wang

Electronic Theses and Dissertations

A "botnet" is a network of compromised computers (bots) that are controlled by an attacker (botmasters). Botnets are one of the most serious threats to today’s Internet; they are the root cause of many current Internet attacks, such as email spam, distributed denial of service (DDoS) attacks , click fraud, etc. There have been many researches on how to detect, monitor, and defend against botnets that have appeared and their attack techniques. However, it is equally important for us to investigate possible attack techniques that could be used by the next generation botnets, and develop effective defense techniques accordingly in …

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Computational Hurricane Hazard Analysis A Performance Based Engineering View, Christopher Michael Vanek Jan 2010

Computational Hurricane Hazard Analysis A Performance Based Engineering View, Christopher Michael Vanek

Electronic Theses and Dissertations

Widespread structural damage to critical facilities such as levees, buildings, dams and bridges during hurricanes has exemplified the need to consider multiple hazards associated with hurricanes as well as the potential for unacceptable levels of performance even if failure is not observed. These inadequate standards warrant the use of more accurate methods to describe the anticipated structural response, and damage for extreme events often termed performance based engineering (PBE). Therefore PBE was extended into the field of hurricane engineering in this study. Application of performance-based principles involves collection of the numerous hazards data from sources such as historical records, laboratory …

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Reactive Control Of Autonomous Dynamical Systems, Jiangmin Chunyu Jan 2010

Reactive Control Of Autonomous Dynamical Systems, Jiangmin Chunyu

Electronic Theses and Dissertations

This thesis mainly consists of five independent papers concerning the reactive control design of autonomous mobile robots in the context of target tracking and cooperative formation keeping with obstacle avoidance in the static/dynamic environment. Technical contents of this thesis are divided into three parts. The first part consists of the first two papers, which consider the target-tracking and obstacle avoidance in the static environment. Especially, in the static environment, a fundamental issue of reactive control design is the local minima problem(LMP) inherent in the potential field methods(PFMs). Through introducing a state-dependent planned goal, the first paper proposes a switching control …

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Fabrication Of Integrated Optofluidic Circuits In Chalcogenide Glass Using Femtosecond Laser Direct Writing, Troy P. Anderson Jan 2010

Fabrication Of Integrated Optofluidic Circuits In Chalcogenide Glass Using Femtosecond Laser Direct Writing, Troy P. Anderson

Electronic Theses and Dissertations

Femtosecond laser direct writing (FLDW) is a versatile process that uses focused femtosecond pulses to modify the physical structure of a material, which can result in a shift of optical properties such as the linear and nonlinear refractive index. If the photon energy of the femtosecond pulses lies below the material bandgap, nonlinear absorption rather than linear absorption becomes the dominant mechanism of energy transfer to the material. In this manner, a focused femtosecond pulse train can be used to fabricate functional features such as optical waveguides, diffractive optical elements, or micro-fluidic elements within the volume of a transparent medium. …

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Nonlinear Absorption And Free Carrier Recombination In Direct Gap Semiconductors, Peter D. Olszak Jan 2010

Nonlinear Absorption And Free Carrier Recombination In Direct Gap Semiconductors, Peter D. Olszak

Electronic Theses and Dissertations

Nonlinear absorption of Indium Antimonide (InSb) has been studied for many years, yet due to the complexity of absorption mechanisms and experimental difficulties in the infrared, this is still a subject of research. Although measurements have been made in the past, a consistent model that worked for both picosecond and nanosecond pulse widths had not been demonstrated. In this project, temperature dependent two-photon (2PA) and free carrier absorption (FCA) spectra of InSb are measured using femtosecond, picosecond, and nanosecond IR sources. The 2PA spectrum is measured at room temperature with femtosecond pulses, and the temperature dependence of 2PA and FCA …

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An Uncertainty Quantification Of The Variation Of Internal Heat Transfer Coefficients And The Effect On Airfoil Life, Jan H. Marsh Jan 2010

An Uncertainty Quantification Of The Variation Of Internal Heat Transfer Coefficients And The Effect On Airfoil Life, Jan H. Marsh

Electronic Theses and Dissertations

Uncertainty in accurately knowing applied internal heat transfer coefficients inside of a cooling passage can lead to variability in predicting low cycle fatigue life of a turbine vane or blade. Under-predicting a life value for a turbine part can have disastrous effects on the engine as a whole, and can negate efforts in innovative design for advanced cooling techniques for turbine components. Quantification of this fatigue life uncertainty utilizing a computational framework is the primary objective of this thesis. Through the use of probabilistic design methodologies a process is developed to simulate uncertainties of internal heat transfer coefficient, which are …

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Plasmon Enhanced Near-Field Interactions In Surface Coupled Nanoparticle Arrays For Integrated Nanophotonic Devices, Amitabh Ghoshal Jan 2010

Plasmon Enhanced Near-Field Interactions In Surface Coupled Nanoparticle Arrays For Integrated Nanophotonic Devices, Amitabh Ghoshal

Electronic Theses and Dissertations

The current thrust towards developing silicon compatible integrated nanophotonic devices is driven by need to overcome critical challenges in electronic circuit technology related to information bandwidth and thermal management. Surface plasmon nanophotonics represents a hybrid technology at the interface of optics and electronics that could address several of the existing challenges. Surface plasmons are electronic charge density waves that can occur at a metal-dielectric interface at optical and infrared frequencies. Numerous plasmon based integrated optical devices such as waveguides, splitters, resonators and multimode interference devices have been developed, however no standard integrated device for coupling light into nanoscale optical circuits …

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New Laser Technologies Analysis Of Quantum Dot And Lithographic Laser Diodes, Abdullah Demir Jan 2010

New Laser Technologies Analysis Of Quantum Dot And Lithographic Laser Diodes, Abdullah Demir

Electronic Theses and Dissertations

The first part of this dissertation presents a comprehensive study of quantum dot (QD) lasers threshold characteristics. The threshold temperature dependence of a QD laser diode is studied in different limits of p-doping, hole level spacing and inhomogeneous broadening. Theoretical analysis shows that the threshold current of a QD laser in the limit of uniform QDs is not temperature independent and actually more temperature sensitive than the quantum well laser. The results also explain the experimental trends of negative characteristic temperature observed in QD lasers and clarify how the carrier distribution mechanisms inside and among the QDs affect the threshold …

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Reconfigurable Architecture For H.264/Avc Variable Block Size Motion Estimation Based On Motion Activity And Adaptive Search Range, Sumedha Kodipyaka Jan 2010

Reconfigurable Architecture For H.264/Avc Variable Block Size Motion Estimation Based On Motion Activity And Adaptive Search Range, Sumedha Kodipyaka

Electronic Theses and Dissertations

Motion Estimation (ME) technique plays a key role in the video coding systems to achieve high compression ratios by removing temporal redundancies among video frames. Especially in the newest H.264/AVC video coding standard, ME engine demands large amount of computational capabilities due to its support for wide range of different block sizes for a given macroblock in order to increase accuracy in finding best matching block in the previous frames. We propose scalable architecture for H.264/AVC Variable Block Size (VBS) Motion Estimation with adaptive computing capability to support various search ranges, input video resolutions, and frame rates. Hardware architecture of …

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Application Of Antenna Synthesis And Digital Signal Processing Techniques For Active Millimeter-Wave Imaging Systems, Wilson Ariel Caba Jan 2010

Application Of Antenna Synthesis And Digital Signal Processing Techniques For Active Millimeter-Wave Imaging Systems, Wilson Ariel Caba

Electronic Theses and Dissertations

Millimeter-wave imaging has gathered attention in recent years for its ability to penetrate clothing, thin layers of soils, and certain construction materials. However, image quality remains a challenge that needs to be addressed. One way of improving image quality is by increasing the dimensions of the collecting aperture. A sparse array can be used to synthesize a larger aperture with a limited set of relatively small detectors. In this research we design, build, and test a test-bed having an active source at 94 GHz and an array of coherent detectors, mounted on arms that extend radially on a rotary table. …

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Modeling And Design Of A Photonic Crystal Chip Hosting A Quantum Network Made Of Single Spins In Quantum Dots That Interact Via Single Photons, Hubert P. Seigneur Jan 2010

Modeling And Design Of A Photonic Crystal Chip Hosting A Quantum Network Made Of Single Spins In Quantum Dots That Interact Via Single Photons, Hubert P. Seigneur

Electronic Theses and Dissertations

In this dissertation, the prospect of a quantum technology based on a photonic crystal chip hosting a quantum network made of quantum dot spins interacting via single photons is investigated. The mathematical procedure to deal with the Liouville-Von Neumann equation, which describes the time-evolution of the density matrix, was derived for an arbitrary system, giving general equations. Using this theoretical groundwork, a numerical model was then developed to study the spatiotemporal dynamics of entanglement between various qubits produced in a controlled way over the entire quantum network. As a result, an efficient quantum interface was engineered allowing for storage qubits …

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Environmental Degradation Of Oxidation Resistant And Thermal Barrier Coatings For Fuel-Flexible Gas Turbine Applications, Prabhakar Mohan Jan 2010

Environmental Degradation Of Oxidation Resistant And Thermal Barrier Coatings For Fuel-Flexible Gas Turbine Applications, Prabhakar Mohan

Electronic Theses and Dissertations

The development of thermal barrier coatings (TBCs) has been undoubtedly the most critical advancement in materials technology for modern gas turbine engines. TBCs are widely used in gas turbine engines for both power-generation and propulsion applications. Metallic oxidation-resistant coatings (ORCs) are also widely employed as a stand-alone protective coating or bond coat for TBCs in many high-temperature applications. Among the widely studied durability issues in these high-temperature protective coatings, one critical challenge that received greater attention in recent years is their resistance to high-temperature degradation due to corrosive deposits arising from fuel impurities and CMAS (calcium-magnesium-alumino-silicate) sand deposits from air …

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Simulation For Commercial Driver License Third Party Tester Testing, Henry Truong Jan 2010

Simulation For Commercial Driver License Third Party Tester Testing, Henry Truong

Electronic Theses and Dissertations

The advance of technology is thought to help ease the myriad tasks that are usually involved in operating equipment. Training and testing in modern times have been replacing with simulation technologies that mimic the actual live operations and testing. Many successful stories of flight simulation come from military fighter aircraft and commercial pilot programs. The possibilities of safety in saving lives, economic incentive in reducing the operational cost and reducing the carbon footprint via simulation makes simulation worth looking into. These considerations quickly boosted the transfer from live training operations to virtual and simulation, as were easily adopted in the …

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Laser Plasma Radiation Studies For Droplet Sources In The Extreme Ultraviolet, Reuvani Kamtaprasad Jan 2010

Laser Plasma Radiation Studies For Droplet Sources In The Extreme Ultraviolet, Reuvani Kamtaprasad

Electronic Theses and Dissertations

The advancement of laboratory based Extreme Ultraviolet (EUV) radiation has escalated with the desire to use EUV as a source for semiconductor device printing. Laser plasmas based on a mass-limited target concept, developed within the Laser Plasma Laboratory demonstrate a much needed versatility for satisfying rigorous source requirements. This concept produces minimal debris concerns and allows for the attainment of high repetition rates as well as the accommodation of various laser and target configurations. This work demonstrates the generation of EUV radiation by creating laser plasmas from mass-limited targets with indium, tin, and antimony doped droplets. Spectral emission from the …

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Transfer And Development Length Of Strands In Post-Tensioned Members After Anchor Head Failure, Elie El Zghayar Jan 2010

Transfer And Development Length Of Strands In Post-Tensioned Members After Anchor Head Failure, Elie El Zghayar

Electronic Theses and Dissertations

Post-tensioning tendons in segmental bridge construction are often only anchored within the deviator and pier segments. The effectiveness of the post-tensioning (PT) system is therefore dependent on proper functioning of the anchorages. On August 28, 2000 a routine inspection of the Mid-Bay Bridge (Okaloosa County, Florida) revealed corrosion in numerous PT tendons. Moreover, one of the 19-strand tendons was completely slacked, with later inspection revealing a corrosion-induced failure at the pier anchor location. Anchorage failure caused all PT force to transfer to the steel duct located within the pier segment that in turn slipped and caused the tendon to go …

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Experimental And Cfd Investigations Of Lifted Tribrachial Flames, Zhiliang Li Jan 2010

Experimental And Cfd Investigations Of Lifted Tribrachial Flames, Zhiliang Li

Electronic Theses and Dissertations

Experimental measurements of the lift-off velocity and lift-off height, and numerical simulations were conducted on the liftoff and stabilization phenomena of laminar jet diffusion flames of inert-diluted C3H8 and CH4 fuels. Both non-reacting and reacting jets were investigated, including effects of multi-component diffusivities and heat release (buoyancy and gas expansion). The role of Schmidt number for non-reacting jets was investigated, with no conclusive Schmidt number criterion for liftoff previously known in similarity solutions. The cold-flow simulation for He-diluted CH4 fuel does not predict flame liftoff; however, adding heat release reaction leads to the prediction of liftoff, which is consistent with …

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A Study Of Factors Contributing To Self-Reported Anomalies In Civil Aviation, Chris Andrzejczak Jan 2010

A Study Of Factors Contributing To Self-Reported Anomalies In Civil Aviation, Chris Andrzejczak

Electronic Theses and Dissertations

A study investigating what factors are present leading to pilots submitting voluntary anomaly reports regarding their flight performance was conducted. The study employed statistical methods, text mining, clustering, and dimensional reduction techniques in an effort to determine relationships between factors and anomalies. A review of the literature was conducted to determine what factors are contributing to these anomalous incidents, as well as what research exists on human error, its causes, and its management. Data from the NASA Aviation Safety Reporting System (ASRS) was analyzed using traditional statistical methods such as frequencies and multinomial logistic regression. Recently formalized approaches in text …

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Control Strategy For Maximizing Power Conversion Efficiency And Effectiveness Of Three Port Solar Charging Station For Electric Vehicles, Christopher Hamilton Jan 2010

Control Strategy For Maximizing Power Conversion Efficiency And Effectiveness Of Three Port Solar Charging Station For Electric Vehicles, Christopher Hamilton

Electronic Theses and Dissertations

Recent trends in the energy sector have provided opportunities in the research of alternative energy sources and optimization of systems that harness these energy sources. With the rising cost of fossil fuel and rising concern about detrimental effects that fossil fuel consumption has on the environment, electric vehicles are becoming more prevalent. A study put out in 2009 gives a prediction that in the year 2025, 20% of new vehicles will be PHEVs.[1] As energy providers become more concerned about a growing population and diminishing energy source, they are looking into alternative energy sources such as wind and solar power. …

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Thermal Performance Of Cryogenic Multilayer Insulation At Various Layer Spacings, Wesley Louis Johnson Jan 2010

Thermal Performance Of Cryogenic Multilayer Insulation At Various Layer Spacings, Wesley Louis Johnson

Electronic Theses and Dissertations

Multilayer insulation (MLI) has been shown to be the best performing cryogenic insulation system at high vacuum (less than 10-3 torr), and is widely used on spaceflight vehicles. Over the past 50 years, many numerous investigations of MLI have yielded a general understanding of the many variables associated with MLI. MLI has been shown to be a function of variables such as warm boundary temperature, the number of reflector layers, and the spacer material in between reflectors, the interstitial gas pressure and the interstitial gas. Because conduction between reflectors increases with the thickness of the spacer material, and yet the …

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Interaction Between Secondary Flow & Film Cooling Jets Of A Realistic Annular Airfoil Cascade (High Mach Number), Cuong Quoc Nguyen Jan 2010

Interaction Between Secondary Flow & Film Cooling Jets Of A Realistic Annular Airfoil Cascade (High Mach Number), Cuong Quoc Nguyen

Electronic Theses and Dissertations

Film cooling is investigated on a flat plate both numerically and experimentally. Conical shaped film hole are investigated extensively and contribute to the current literature data, which is extremely rare in the open public domain. Both configuration of the cylindrical film holes, with and without a trench, are investigated in detail. Design of experiment technique was performed to find an optimum combination of both geometrical and fluid parameters to achieve the best film cooling performance. From this part of the study, it shows that film cooling performance can be enhanced up to 250% with the trenched film cooling versus non-trenched …

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Design Of Low-Capacitance And High-Speed Electrostatic Discharge (Esd) Devices For Low-Voltage Protection Applications, You Li Jan 2010

Design Of Low-Capacitance And High-Speed Electrostatic Discharge (Esd) Devices For Low-Voltage Protection Applications, You Li

Electronic Theses and Dissertations

Electrostatic discharge (ESD) is defined as the transfer of charge between bodies at different potentials. The electrostatic discharge induced integrated circuit damages occur throughout the whole life of a product from the manufacturing, testing, shipping, handing, to end user operating stages. This is particularly true as microelectronics technology continues shrink to nano-metric dimensions. The ESD related failures is a major IC reliability concern and results in a loss of millions dollars to the semiconductor industry each year. Several ESD stress models and test methods have been developed to reproduce the real world ESD discharge events and quantify the sensitivity of …

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Branched And Spiral Organic Nanotubes Based On The Self-Assembly Of Bile Acids, Xuejun Zhang Jan 2010

Branched And Spiral Organic Nanotubes Based On The Self-Assembly Of Bile Acids, Xuejun Zhang

Electronic Theses and Dissertations

The self-assembly of chiral amphiphilic molecules in aqueous solutions is of particular interest because the chirality of individual molecules is often expressed in their supermolecular structures. Self-assembled tubes made of chiral amphiphilic molecules represent useful supramolecular architectures which hold promise as controlled release vehicles for drug delivery, encapsulates for functional molecules, and nanoreactors for chemical reactions. Lithocholic acid (LCA) is a secondary bile acid with the concentration being identical to that of cholesterol in the hepatic bile and gallbladder. It has a rigid, nearly planar hydrophobic steroid nucleus, with four hydrogen atoms and one hydroxyl group directed toward the concave …

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Tuning The Properties Of Nanomaterials As Function Of Surface And Environment, Ajay Karakoti Jan 2010

Tuning The Properties Of Nanomaterials As Function Of Surface And Environment, Ajay Karakoti

Electronic Theses and Dissertations

Nanotechnology has shaped the research and development in various disciplines of science and technology by redefining the interdisciplinary research. It has put the materials science at the forefront of technology by allowing the researchers to engineer materials with properties ranging from electronics to biomedical by using materials as diverse as ceramics to just plain carbon. These exceptional properties are achieved by minimizing the dimension of particles in such smaller domains that the boundary between the individual atoms, ions or cluster of particles is very small. This results in a change in conventional properties of particles from continuum physics to quantum …

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Researches On Reverse Lookup Problem In Distributed File System, Junyao Zhang Jan 2010

Researches On Reverse Lookup Problem In Distributed File System, Junyao Zhang

Electronic Theses and Dissertations

Recent years have witnessed an increasing demand for super data clusters. The super data clusters have reached the petabyte-scale can consist of thousands or tens of thousands storage nodes at a single site. For this architecture, reliability is becoming a great concern. In order to achieve a high reliability, data recovery and node reconstruction is a must. Although extensive research works have investigated how to sustain high performance and high reliability in case of node failures at large scale, a reverse lookup problem, namely finding the objects list for the failed node remains open. This is especially true for storage …

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Experimental Studies Of Liquefaction And Densification Of Liquid Oxygen, Jonathan Koert Partridge Jan 2010

Experimental Studies Of Liquefaction And Densification Of Liquid Oxygen, Jonathan Koert Partridge

Electronic Theses and Dissertations

Rocketry employs cryogenic refrigeration to increase the density of propellants, such as oxygen, and stores the propellant as a liquid. In addition to propellant liquefaction, cryogenic refrigeration can also conserve propellant and provide propellant subcooling and densification. Previous studies analyzed vapor conditioning of a cryogenic propellant, which occurred by either a heat exchanger positioned in the vapor or by using the vapor as the working fluid in a refrigeration cycle. This study analyzes the refrigeration effects of a heat exchanger located beneath the vapor-liquid interface of liquid oxygen. This study predicts the mass liquefaction rate and heat transfer coefficient for …

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Evaluating The Benefits Of 3d Stereo In Modern Video Games, Tad Litwiller Jan 2010

Evaluating The Benefits Of 3d Stereo In Modern Video Games, Tad Litwiller

Electronic Theses and Dissertations

We present a study that investigates user performance benefits of 3D stereo in modern video games. Based on an analysis of several video games that are best suited for use with commercial 3D stereo drivers and vision systems, we chose five modern titles focusing on racing, first person shooter, third person shooter, and sports game genres. For each game, quantitative and qualitative measures were taken to determine if users performed better and learned faster in the experimental group (3D stereo display) than in the control group (2D display). A game experience pre-questionnaire was used to classify participants into beginner, intermediate, …

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