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Articles 1 - 30 of 145
Full-Text Articles in Engineering
Synthesis, Structure, And Catalytic Properties Of Size-Selected Platinum Nanoparticles, Simon Armando Covone
Synthesis, Structure, And Catalytic Properties Of Size-Selected Platinum Nanoparticles, Simon Armando Covone
Electronic Theses and Dissertations
The use of heterogeneous catalysis is well established in chemical synthesis, energy, and environmental engineering applications. Supported Pt nanoparticles have been widely reported to act as catalysts in a vast number of chemical reactions. In this report, the performance of Pt/ZrO2 nanocatalyst for the decomposition of methanol, ethanol, 2-propanol, and 2-butanol is investigated. The potential of each alcohol for the production of H2 and other relevant products in the presence of a catalyst is studied. All the alcohols studied show some decomposition activity below 200°C which increased with increasing temperature. In all cases, high selectivity towards H2 formation is observed. …
Characterization Of Aluminum Doped Zinc Oxide Thin Films For Photovoltaic Applications, Bojanna P. Shantheyanda
Characterization Of Aluminum Doped Zinc Oxide Thin Films For Photovoltaic Applications, Bojanna P. Shantheyanda
Electronic Theses and Dissertations
Growing demand for clean source of energy in the recent years has increased the manufacture of solar cells for converting sun energy directly into electricity. Research has been carried out around the world to make a cheaper and more efficient solar cell technology by employing new architectural designs and developing new materials to serve as light absorbers and charge carriers. Aluminum doped Zinc Oxide thin film, a Transparent conductive Oxides (TCO) is used as a window material in the solar cell these days. Its increased stability in the reduced ambient, less expensive and more abundance make it popular among the …
Analysis And Optimization Of A Solar Thermal Collector With Integrated Storage, Monica Bonadies
Analysis And Optimization Of A Solar Thermal Collector With Integrated Storage, Monica Bonadies
Electronic Theses and Dissertations
Solar energy, a topic popular in the United States during the oil embargo of the 1970’s, has become a relevant topic once more with the current focus on reducing greenhouse emissions. Solar thermal energy in particular has become popular as it uses existing steam turbine technology to produce electricity, with the benefit of using solar energy to produce steam rather than coal or nuclear heat sources. Solar thermal can also be used at lower temperatures to heat water for pools or for residential use. While this energy source has its benefits, it has the problem of being opportunistic – the …
Experimental And Theoretical Approaches To Characterization Of Electronic Nonlinearities In Direct-Gap Semiconductors, Claudiu Cirloganu
Experimental And Theoretical Approaches To Characterization Of Electronic Nonlinearities In Direct-Gap Semiconductors, Claudiu Cirloganu
Electronic Theses and Dissertations
The general goal of this dissertation is to provide a comprehensive description of the limitations of established theories on bound electronic nonlinearities in direct-gap semiconductors by performing various experiments on wide and narrow bandgap semiconductors along with developing theoretical models. Nondegenerate two-photon absorption (2PA) is studied in several semiconductors showing orders of magnitude enhancement over the degenerate counterpart. In addition, three-photon absorption (3PA) is studied in ZnSe and other semiconductors and a new theory using a Kane 4-band model is developed which fits new data well. Finally, the narrow gap semiconductor InSb is studied with regard to multiphoton absorption, free-carrier …
A Decision Support System Methodology For The Selection Of Rapid Prototyping Technologies For Investment-Cast Gas Turbine Parts, Angela Gallagher
A Decision Support System Methodology For The Selection Of Rapid Prototyping Technologies For Investment-Cast Gas Turbine Parts, Angela Gallagher
Electronic Theses and Dissertations
In the power generation sector, more specifically, the gas turbine industry, competition has forced the lead time-to-market for product advancements to be more important than ever. For design engineers, this means that product design iterations and final product development must be completed within both critical time windows and budgetary constraints. Therefore, two areas that have received significant attention in the research and in practice are: (1) rapid prototyping technology development, and (2) rapid prototyping technology selection. Rapid prototyping technology selection is the focus of this research. In practice, selecting the rapid prototyping method that is acceptable for a specific design …
Toward A Real-Time Celestial Body Information System, Brian Mitchell Guise
Toward A Real-Time Celestial Body Information System, Brian Mitchell Guise
Electronic Theses and Dissertations
The National Aeronautics and Space Administration maintains a challenging schedule of planned and on-going space exploration missions that extend to the outer reaches of our galaxy. New missions represent a huge investment, in terms of actual costs for equipment and support infrastructure, and personnel training. The success of a mission is critical considering both the monetary investment, and for manned missions, the lives which are put at risk. Tragedies involving Challenger, Columbia, Apollo 7, and the near tragedy of Apollo 13 exemplify that space exploration is a dangerous endeavor, posing extreme environmental conditions on both equipment and personnel. NASA, the …
Tuning The Properties Of Nanomaterials As Function Of Surface And Environment, Ajay Karakoti
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 …
A Study Of Factors Contributing To Self-Reported Anomalies In Civil Aviation, Chris Andrzejczak
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 …
Concentric Layout, A New Scientific Data Layout For Matrix Data Set In Hadoop File System, Lu Cheng
Concentric Layout, A New Scientific Data Layout For Matrix Data Set In Hadoop File System, Lu Cheng
Electronic Theses and Dissertations
The data generated by scientific simulation, sensor, monitor or optical telescope has increased with dramatic speed. In order to analyze the raw data speed and space efficiently, data preprocess operation is needed to achieve better performance in data analysis phase. Current research shows an increasing tread of adopting MapReduce framework for large scale data processing. However, the data access patterns which generally applied to scientific data set are not supported by current MapReduce framework directly. The gap between the requirement from analytics application and the property of MapReduce framework motivates us to provide support for these data access patterns in …
Reactive Control Of Autonomous Dynamical Systems, Jiangmin Chunyu
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 …
Learning From Geometry In Learning For Tactical And Strategic Decision Domains, Jason Gauci
Learning From Geometry In Learning For Tactical And Strategic Decision Domains, Jason Gauci
Electronic Theses and Dissertations
Artificial neural networks (ANNs) are an abstraction of the low-level architecture of biological brains that are often applied in general problem solving and function approximation. Neuroevolution (NE), i.e. the evolution of ANNs, has proven effective at solving problems in a variety of domains. Information from the domain is input to the ANN, which outputs its desired actions. This dissertation presents a new NE algorithm called Hypercube-based NeuroEvolution of Augmenting Topologies (HyperNEAT), based on a novel indirect encoding of ANNs. The key insight in HyperNEAT is to make the algorithm aware of the geometry in which the ANNs are embedded and …
Text Versus Verbal Real-Time Feedback During Simulation-Based Training Of Higher-Order Cognitive Skills, C L. Fiorella
Text Versus Verbal Real-Time Feedback During Simulation-Based Training Of Higher-Order Cognitive Skills, C L. Fiorella
Electronic Theses and Dissertations
A crucial component of instructional design for simulation-based training systems involves optimizing the presentation of complex material in order to maximize knowledge acquisition and application. One approach toward facilitating the learning of this complex information is to instantiate instructional strategies within the training systems themselves. However, there are few established guidelines in place which are meant specifically for real-time guidance strategies within simulation-based environments. Consequently, this study aims to apply findings from the literature on instructional information presentation to drive decisions for how to most effectively provide real-time feedback during training of simulated decision-making tasks. Research has shown that presenting …
Effects Of Flight Factors On Pilot Performance, Workload, And Stress At Final Approach To Landing Phase Of Flight, Kyongsun Lee
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 …
Phoneme-Based Video Indexing Using Phonetic Disparity Search, Carlos Leon Barth
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 …
Modeling And Simulation Of Soft Bodies, Jaruwan Mesit
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 …
Optimization Of Process Parameters For Reduced Thickness Cigses Thin Film Solar Cells, Shirish A. Pethe
Optimization Of Process Parameters For Reduced Thickness Cigses Thin Film Solar Cells, Shirish A. Pethe
Electronic Theses and Dissertations
With the advent of the 21st century, one of the serious problems facing mankind is harmful effects of global warming. Add to that the ever increasing cost of fuel and the importance of development of clean energy resources as alternative to fossil fuel has becomes one of the prime and pressing challenges for modern science and technology in the 21st century. Recent studies have shown that energy related sources account for 50% of the total emission of carbon dioxide in the atmosphere. All research activities are focused on developing various technologies that are capable of converting sunlight into electricity with …
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 …
Extreme Ultraviolet Spectral Streak Camera, John Michael Szilagyi
Extreme Ultraviolet Spectral Streak Camera, John Michael Szilagyi
Electronic Theses and Dissertations
The recent development of extreme ultraviolet (EUV) sources has increased the need for diagnostic tools, and has opened up a previously limited portion of the spectrum. With ultrafast laser systems and spectroscopy moving into shorter timescales and wavelengths, the need for nanosecond scale imaging of EUV is increasing. EUV’s high absorption has limited the number of imaging options due to the many atomic resonances in this spectrum. Currently EUV is imaged with photodiodes and X-ray CCDs. However photodiodes are limited in that they can only resolve intensity with respect to time and X-ray CCDs are limited to temporal resolution in …
Accelerated Life Testing Of Subsea Equipment Under Hydrostatic Pressure, Amar Raja Thiraviam
Accelerated Life Testing Of Subsea Equipment Under Hydrostatic Pressure, Amar Raja Thiraviam
Electronic Theses and Dissertations
Accelerated Life Testing (ALT) is an effective method of demonstrating and improving product reliability in applications where the products are expected to perform for a long period of time. ALT accelerates a given failure mode by testing at amplified stress level(s) in excess of operational limits. Statistical analysis (parameter estimation) is then performed on the data, based on an acceleration model to make life predictions at use level. The acceleration model thus forms the basis of accelerated life testing methodology. Well established accelerated models such as the Arrhenius model and the Inverse Power Law (IPL) model exist for key stresses …
Computational Hurricane Hazard Analysis A Performance Based Engineering View, Christopher Michael Vanek
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 …
The Next Generation Botnet Attacks And Defenses, Ping Wang
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 …
Film Cooling With Wake Passing Applied To An Annular Endwall, Nghia Trong Tran
Film Cooling With Wake Passing Applied To An Annular Endwall, Nghia Trong Tran
Electronic Theses and Dissertations
Advancement in turbine technology has far reaching effects on today's society and environment. With more than 90% of electricity and 100% of commercial air transport being produced by the usage of gas turbine, any advancement in turbine technology can have an impact on fuel used, pollutants and carbon dioxide emitted to the environment. Within the turbine engine, fully understanding film cooling is critical to reliability of a turbine engine. Film cooling is an efficient way to protect the engine surface from the extremely hot incoming gas, which is at a temperature much higher than allowable temperature of even the most …
Branched And Spiral Organic Nanotubes Based On The Self-Assembly Of Bile Acids, Xuejun Zhang
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 …
Researches On Reverse Lookup Problem In Distributed File System, Junyao Zhang
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 …
Assessment Of Aquifer Storage And Recovery Impact On Phosphorus Stability In Lake Sediment, Sha Liu
Assessment Of Aquifer Storage And Recovery Impact On Phosphorus Stability In Lake Sediment, Sha Liu
Electronic Theses and Dissertations
Lake Okeechobee, the second largest natural freshwater lake in the United States, had experienced a historical drought in 2007-2008 and the inflow to Lake Okeechobee has been reduced by 40% of the average daily mean between warm phase and cold phase due to the impact of Atlantic Multidecadal Oscillation in the past six decades. To cope with this water resources management problem, the US Army Corps of Engineers (USACE) proposed the largest national implementation plan of aquifer storage and recovery (ASR) project in the Kissimmee River Basin. Routine operation of ASR will deliver recovered water from ASR wells into the …
Analysis Of The Florida's Showcase Green Envirohome Water/Wastewater Systems And Development Of A Cost-Benefit Green Roof Optimization Model, Brian Rivera
Electronic Theses and Dissertations
The Florida Showcase Green Envirohome (FSGE) incorporates many green technologies. FSGE is built to meet or exceed 12 green building guidelines and obtain 8 green building certificates. The two-story 3292 ft2 home is a "Near Zero-Loss Home", "Near Zero-Energy Home", "Near Zero-Runoff Home", and "Near Zero-Maintenance Home". It is spawned from the consumer-driven necessity to build a home resistant to hurricanes, tornadoes, floods, fire, mold, termites, impacts, and even earthquakes given up to 500% increase in insurance premiums in natural disaster zones, the dwindling flexibility and coverage of insurance policies, and rising energy, water and maintenance costs (FSGE 2008). The …
Designing Of Energy Efficient Indoor Environments Using A Localized Radial Basis Function Meshless Method, Victor Huayamave
Designing Of Energy Efficient Indoor Environments Using A Localized Radial Basis Function Meshless Method, Victor Huayamave
Electronic Theses and Dissertations
Around the world, the energy over consumption issue has been one of the key socio-economic and political challenges, which has drastically worsened over the last few years. Over the years engineers and environmentalists have proposed several approaches to improve energy efficiency. One is to reduce energy demand by improving consumption habits and a second approach is to introduce the use of a "greener" concept by using biomaterials in a diverse and more efficient manner in engineering construction to create energy efficient environments. This work will investigate the effects of using "green" stabilized earth materials to provide and enhance thermal regulation …
Vaporization Characteristics Of Pure And Blended Biofuel Droplet Injected Into Hot Stream Of Air, Abhishek Saha
Vaporization Characteristics Of Pure And Blended Biofuel Droplet Injected Into Hot Stream Of Air, Abhishek Saha
Electronic Theses and Dissertations
The combustion dynamics and stability are dependent on the quality of mixing and vaporization of the liquid fuel in the pre-mixer. The vaporization characteristics of different blends of biofuel droplets injected into the air stream in the pre-mixer are modeled in this current study. The focus of this work is on the blended alternate fuels which are lately being considered for commercial use. Two major alternate fuels analyzed are ethanol and Rapeseed Methyl Esters (RME). Ethanol is being used as a substitute for gasoline, while RME is an alternative for diesel. In the current work, the vaporization characteristics of a …
Analyzing Instructtion Based Cache Replacement Policies, Ping Xiang
Analyzing Instructtion Based Cache Replacement Policies, Ping Xiang
Electronic Theses and Dissertations
The increasing speed gap between microprocessors and off-chip DRAM makes last-level caches (LLCs) a critical component for computer performance. Multi core processors aggravate the problem since multiple processor cores compete for the LLC. As a result, LLCs typically consume a significant amount of the die area and effective utilization of LLCs is mandatory for both performance and power efficiency. We present a novel replacement policy for last-level caches (LLCs). The fundamental observation is to view LLCs as a shared resource among multiple address streams with each stream being generated by a static memory access instruction. The management of LLCs in …
Episodic Memory Model For Embodied Conversational Agents, Miguel Elvir
Episodic Memory Model For Embodied Conversational Agents, Miguel Elvir
Electronic Theses and Dissertations
Embodied Conversational Agents (ECA) form part of a range of virtual characters whose intended purpose include engaging in natural conversations with human users. While works in literature are ripe with descriptions of attempts at producing viable ECA architectures, few authors have addressed the role of episodic memory models in conversational agents. This form of memory, which provides a sense of autobiographic record-keeping in humans, has only recently been peripherally integrated into dialog management tools for ECAs. In our work, we propose to take a closer look at the shared characteristics of episodic memory models in recent examples from the field. …