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Articles 1 - 30 of 153
Full-Text Articles in Engineering
Mechanisms Of Lifetime Improvement In Thermal Barrier Coatings With Hf And/Or Y Modification Of Cmsx-4 Superalloy Substrates, Jing Liu
Electronic Theses and Dissertations
In modern turbine engines for propulsion and energy generation, thermal barrier coating (TBCs) protect hot-section blades and vanes, and play a critical role in enhancing reliability, durability and operation efficiency. In this study, thermal cyclic lifetime and microstructural degradation of electron beam physical vapor deposited (EB-PVD) Yttria Stabilized Zirconia (YSZ) with (Ni,Pt)Al bond coat and Hf- and/or Y- modified CMSX-4 superalloy substrates were examined. Thermal cyclic lifetime of TBCs was measured using a furnace thermal cycle test that consisted of 10-minute heat-up, 50-minute dwell at 1135C, and 10-minute forced-air-quench. TBC lifetime was observed to improve from 600 cycles to over …
Recognizing Teamwork Activity In Observations Of Embodied Agents, Linus Jan Luotsinen
Recognizing Teamwork Activity In Observations Of Embodied Agents, Linus Jan Luotsinen
Electronic Theses and Dissertations
This thesis presents contributions to the theory and practice of team activity recognition. A particular focus of our work was to improve our ability to collect and label representative samples, thus making the team activity recognition more efficient. A second focus of our work is improving the robustness of the recognition process in the presence of noisy and distorted data. The main contributions of this thesis are as follows: We developed a software tool, the Teamwork Scenario Editor (TSE), for the acquisition, segmentation and labeling of teamwork data. Using the TSE we acquired a corpus of labeled team actions both …
Network Performance Management Using Application-Centric Key Performance Indicators, Susan Mcgill
Network Performance Management Using Application-Centric Key Performance Indicators, Susan Mcgill
Electronic Theses and Dissertations
The Internet and intranets are viewed as capable of supplying "Anything, Anywhere, Anytime" and e-commerce, e-government, e-community, and military C4I are now deploying many and varied applications to serve their needs. Network management is currently centralized in operations centers. To assure customer satisfaction with the network performance they typically plan, configure and monitor the network devices to insure an excess of bandwidth, that is overprovision. If this proves uneconomical or if complex and poorly understood interactions of equipment, protocols and application traffic degrade performance creating customer dissatisfaction, another more application-centric, way of managing the network will be needed. This research …
Thermodynamic Studies On The Synthesis Of Nitrides And Epitaxial Growth Of Ingan, Zinki Monga
Thermodynamic Studies On The Synthesis Of Nitrides And Epitaxial Growth Of Ingan, Zinki Monga
Electronic Theses and Dissertations
Nitride semiconductor materials have been used in a variety of applications, such as LEDs, lasers, photovoltaic cells and medical applications. If incandescent bulbs could be replaced by white GaN LEDs, they would not only provide compactness and longer lifetime, but this would also result in huge energy savings. A renewed interest in InGaN emerged recently after it was discovered that the band gap for InN is 0.7eV, instead of the previously published value of 1.9eV. Thus InGaN solid solutions cover almost the whole visible spectrum, from a band gap of 3.34eV for GaN and 0.7eV for InN. Hence, InGaN can …
Learning Geometry-Free Face Re-Lighting, Thomas Brendan Moore
Learning Geometry-Free Face Re-Lighting, Thomas Brendan Moore
Electronic Theses and Dissertations
The accurate modeling of the variability of illumination in a class of images is a fundamental problem that occurs in many areas of computer vision and graphics. For instance, in computer vision there is the problem of facial recognition. Simply, one would hope to be able to identify a known face under any illumination. On the other hand, in graphics one could imagine a system that, given an image, the illumination model could be identified and then used to create new images. In this thesis we describe a method for learning the illumination model for a class of images. Once …
Comparison Of Thm Formation During Disinfection: Ferrate Versus Free Chlorine For Different Source Waters, Adhem Mukattash
Comparison Of Thm Formation During Disinfection: Ferrate Versus Free Chlorine For Different Source Waters, Adhem Mukattash
Electronic Theses and Dissertations
The objective of the study was to compare the trihalomethanes (THMs) produced from ferrate with hypochlorite and to determine how different the THM production would be for a given degree of disinfection (3 log reduction in Heterotrophic Plate Count (HPC)). Different water samples were collected from Lake Claire, Atlantic Ocean, and secondary effluent from an advanced wastewater treatment plant. THM formation was determined using a standard assay over 7 days at room temperature. In addition samples were tested for Total Coliform Escherichia coli (TC/E.coli), and heterotrophic bacteria using HPC by spreadplating on R2A agar. Dissolved organic carbon (DOC) was measured …
Mass Customization Strategies And Their Relationship To Lean Production In The Homebuilding Industry, Isabelina Nahmens
Mass Customization Strategies And Their Relationship To Lean Production In The Homebuilding Industry, Isabelina Nahmens
Electronic Theses and Dissertations
Current housing trends point to an increasing interest from homebuyers to demand houses that reflect their personal and unique styles, and which are individually configured according to these needs (NAHB, 2004). These homebuyers in turn are unwilling to settle for standard models that sacrifice what they really want in a home. At the same time this creates pressure on builders who are reluctant to sacrifice production efficiencies by deviating from standard models. Such customization desired by demanding customers can disrupt the entire estimating, production, delivery and management process, making it even more difficult to manage homebuilding efficiently and effectively. The …
Target Element Sizes For Finite Element Tidal Models From A Domain-Wide, Localized Truncation Error Analysis Incorporating Botto, Denwood Parrish
Target Element Sizes For Finite Element Tidal Models From A Domain-Wide, Localized Truncation Error Analysis Incorporating Botto, Denwood Parrish
Electronic Theses and Dissertations
A new methodology for the determination of target element sizes for the construction of finite element meshes applicable to the simulation of tidal flow in coastal and oceanic domains is developed and tested. The methodology is consistent with the discrete physics of tidal flow, and includes the effects of bottom stress. The method enables the estimation of the localized truncation error of the nonconservative momentum equations throughout a triangulated data set of water surface elevation and flow velocity. The method's domain-wide applicability is due in part to the formulation of a new localized truncation error estimator in terms of complex …
A Hybrid Routing Protocol For Communications Among Nodes Withhigh Relative Speed In Wireless Mesh Networks, Nikolaos Peppas
A Hybrid Routing Protocol For Communications Among Nodes Withhigh Relative Speed In Wireless Mesh Networks, Nikolaos Peppas
Electronic Theses and Dissertations
Wireless mesh networks (WMN) is a new promising wireless technology which uses already available hardware and software components. This thesis proposes a routing algorithm for military applications. More specifically, a specialized scenario consisting of a network of flying Unmanned Aerial Vehicles (UAVs) executing reconnaissance missions is investigated. The proposed routing algorithm is hybrid in nature and uses both reactive and proactive routing characteristics to transmit information. Through simulations run on a specially built stand alone simulator, based on Java, packet overhead, delivery ratio and latency metrics were monitored with respect to varying number of nodes, node density and mobility. The …
Dynamic Speed Monitoring System Effectiveness On Sharp Curves, Vasu Tavasna Persaud
Dynamic Speed Monitoring System Effectiveness On Sharp Curves, Vasu Tavasna Persaud
Electronic Theses and Dissertations
The design of rural interchanges is of critical concern due to the need for the safe transition of vehicles from one high speed roadways to another and vice versa. This transition is accomplished by entry and exit ramps of various forms. The southbound entry loop ramp at the US 27/ US 192 trumpet interchange in Polk County, Florida does not provide such safe transition since historically there has been a high incidence of vehicular off-tracking. The geometry of the southbound entry ramp coupled with high approach speeds are two of the contributing factors. Due to the high cost of interchange …
Optimizing The Design Of Multimodal User Interfaces, Leah Reeves
Optimizing The Design Of Multimodal User Interfaces, Leah Reeves
Electronic Theses and Dissertations
Due to a current lack of principle-driven multimodal user interface design guidelines, designers may encounter difficulties when choosing the most appropriate display modality for given users or specific tasks (e.g., verbal versus spatial tasks). The development of multimodal display guidelines from both a user and task domain perspective is thus critical to the achievement of successful human-system interaction. Specifically, there is a need to determine how to design task information presentation (e.g., via which modalities) to capitalize on an individual operator's information processing capabilities and the inherent efficiencies associated with redundant sensory information, thereby alleviating information overload. The present effort …
A Neat Approach To Genetic Programming, Adelein Rodriguez
A Neat Approach To Genetic Programming, Adelein Rodriguez
Electronic Theses and Dissertations
The evolution of explicitly represented topologies such as graphs involves devising methods for mutating, comparing and combining structures in meaningful ways and identifying and maintaining the necessary topological diversity. Research has been conducted in the area of the evolution of trees in genetic programming and of neural networks and some of these problems have been addressed independently by the different research communities. In the domain of neural networks, NEAT (Neuroevolution of Augmenting Topologies) has shown to be a successful method for evolving increasingly complex networks. This system's success is based on three interrelated elements: speciation, marking of historical information in …
Image-Space Approach To Real-Time Realistic Rendering, Musawir Shah
Image-Space Approach To Real-Time Realistic Rendering, Musawir Shah
Electronic Theses and Dissertations
One of the main goals of computer graphics is the fast synthesis of photorealistic image of virtual 3D scenes. The work presented in this thesis addresses this goal of speed and realism. In real-time realistic rendering, we encounter certain problems that are difficult to solve in the traditional 3-dimensional geometric space. We show that using an image-space approach can provide effective solutions to these problems. Unlike geometric space algorithms that operate on 3D primitives such as points, edges, and polygons, image-space algorithms operate on 2D snapshot images of the 3D geometric data. Operating in image-space effectively decouples the geometric complexity …
Optimization Models For Emergency Relief Shelter Planning For Anticipated Hurricane Events, Abeer Tarief Sharawi
Optimization Models For Emergency Relief Shelter Planning For Anticipated Hurricane Events, Abeer Tarief Sharawi
Electronic Theses and Dissertations
Natural disasters, specifically hurricanes, can cause catastrophic loss of life and property. In recent years, the United States has endured significant losses due to a series of devastating hurricanes (e.g., Hurricanes Charley and Ivan in 2004, and Hurricanes Katrina and Wilma in 2005). Several Federal authorities report that there are weaknesses in the emergency and disaster planning and response models that are currently employed in practice, thus creating a need for better decision models in emergency situations. The current models not only lack fast communication with emergency responders and the public, but are also inadequate for advising the pre-positioning of …
Behavior Of Variable-Length Genetic Algorithms Under Random Selection, Harold Stringer
Behavior Of Variable-Length Genetic Algorithms Under Random Selection, Harold Stringer
Electronic Theses and Dissertations
In this work, we show how a variable-length genetic algorithm naturally evolves populations whose mean chromosome length grows shorter over time. A reduction in chromosome length occurs when selection is absent from the GA. Specifically, we divide the mating space into five distinct areas and provide a probabilistic and empirical analysis of the ability of matings in each area to produce children whose size is shorter than the parent generation's average size. Diversity of size within a GA's population is shown to be a necessary condition for a reduction in mean chromosome length to take place. We show how a …
A Multi-Layer Fpga Framework Supporting Autonomous Runtime Partial Reconfiguration, Heng Tan
A Multi-Layer Fpga Framework Supporting Autonomous Runtime Partial Reconfiguration, Heng Tan
Electronic Theses and Dissertations
Partial reconfiguration is a unique capability provided by several Field Programmable Gate Array (FPGA) vendors recently, which involves altering part of the programmed design within an SRAM-based FPGA at run-time. In this dissertation, a Multilayer Runtime Reconfiguration Architecture (MRRA) is developed, evaluated, and refined for Autonomous Runtime Partial Reconfiguration of FPGA devices. Under the proposed MRRA paradigm, FPGA configurations can be manipulated at runtime using on-chip resources. Operations are partitioned into Logic, Translation, and Reconfiguration layers along with a standardized set of Application Programming Interfaces (APIs). At each level, resource details are encapsulated and managed for efficiency and portability during …
Vacancy Engineered Doped And Undoped Nanocrystalline Rare Earth Oxide Particles For High Temperature Oxidation Resistant Coating, Ranjith Thanneeru
Vacancy Engineered Doped And Undoped Nanocrystalline Rare Earth Oxide Particles For High Temperature Oxidation Resistant Coating, Ranjith Thanneeru
Electronic Theses and Dissertations
Rare earth oxides with trivalent lattice dopants have been of great interest to researchers in the recent years due to its potential applications in catalysis and high temperature protective coatings. The ability to store oxygen in rare earths is the basis for catalysis because of the ability to change valence states which causes the presence of intrinsic oxygen vacancies in the crystal lattice. Although, several doped-rare earth oxide systems in micron scale have been investigated, the doping effect in cerium oxide nanoparticles with well characterized particle size has not been studied. The doping of ceria at that small size can …
Microwave Synthesis Of Nanocrystalline Hydroxy Apatite And Comparison Of Its Biomechanical Properties With Tio2 Structures, Saurabh Verma
Microwave Synthesis Of Nanocrystalline Hydroxy Apatite And Comparison Of Its Biomechanical Properties With Tio2 Structures, Saurabh Verma
Electronic Theses and Dissertations
Nanocrystalline hydroxyapatite (HAp) powder of size 10-20 nm was synthesized applying microwave radiation using calcium nitrate tetrahydrate and sodium phosphate dibasic anhydrous as the starting materials. Microwave power of 600 W and Ca/P ratio of 1.66 in the starting chemicals served as the major factors in the synthesis of nanocrystalline HAp powder. Phase composition and evolution were studied using X-ray diffraction (XRD) technique. Morphology, agglomeration and particle-size of the synthesized powder were studied using Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) techniques. Energy Dispersive Spectrum (EDS) was used to determine the elemental composition of the powder. Thermal properties …
Plasma Processing For Retention Of Nanostructures, Viswanathan Venkatachalapathy
Plasma Processing For Retention Of Nanostructures, Viswanathan Venkatachalapathy
Electronic Theses and Dissertations
Plasma spray processing is a technique that is used extensively in thermal barrier coatings on gas and steam turbine components, biomedical implants and automotive components. Many processing parameters are involved to achieve a coating with certain functionality. The coating could be required to function as thermal barrier, wear resistant, corrosion resistant or a high temperature oxidation resistant coating. Various parameters, such as, nozzle and electrode design, powder feeding system, spray distances, substrate temperature and roughness, plasma gas flow rates and others can greatly alter the coating quality and resulting performance. Feedstock (powder or solution precursor) composition and morphology are some …
Shock-Tube Investigation Of Ignition Delay Times Of Blends Of Methane And Ethane With Oxygen, Brian Christopher Walker
Shock-Tube Investigation Of Ignition Delay Times Of Blends Of Methane And Ethane With Oxygen, Brian Christopher Walker
Electronic Theses and Dissertations
The combustion behavior of methane and ethane is important to the study of natural gas and other alternative fuels that are comprised primarily of these two basic hydrocarbons. Understanding the transition from methane-dominated ignition kinetics to ethane-dominated kinetics for increasing levels of ethane is also of fundamental interest toward the understanding of hydrocarbon chemical kinetics. Much research has been conducted on the two fuels individually, but experimental data of the combustion of blends of methane and ethane is limited to ratios that recreate typical natural gas compositions (up to ~20% ethane molar concentration). The goal of this study was to …
A Study Of Equatorial Ionopsheric Variability Using Signal Processing Techniques, Xiaoni Wang
A Study Of Equatorial Ionopsheric Variability Using Signal Processing Techniques, Xiaoni Wang
Electronic Theses and Dissertations
The dependence of equatorial ionosphere on solar irradiances and geomagnetic activity are studied in this dissertation using signal processing techniques. The statistical time series, digital signal processing and wavelet methods are applied to study the ionospheric variations. The ionospheric data used are the Total Electron Content (TEC) and the critical frequency of the F2 layer (foF2). Solar irradiance data are from recent satellites, the Student Nitric Oxide Explorer (SNOE) satellite and the Thermosphere Ionosphere Mesosphere Energetics Dynamics (TIMED) satellite. The Disturbance Storm-Time (Dst) index is used as a proxy of geomagnetic activity in the equatorial region. The results are summarized …
Cognitive Learning From Computer-Based Information Systems By Incorporating Knowledge Construction Interventions, Wajdi Wazzan
Cognitive Learning From Computer-Based Information Systems By Incorporating Knowledge Construction Interventions, Wajdi Wazzan
Electronic Theses and Dissertations
The aim of the present study was to develop and empirically evaluate different categories of instructional activities, which stimulate the generation and construction of knowledge on the part of an individual student. These generative activities are primed by prompts or scaffolds, which can easily be inserted into specific curriculum addressing any domain of knowledge. To assess the manner in which the knowledge construction interventions influence the learning outcomes from computerized information systems, we have developed an online computer-based information system that describes the functions and mechanisms associated with the bus system of the US army Abrams M1A2 tank. Seven versions …
Assessment Of The Contribution Of Game-Based Simulation In The Advancement Of Individual Soldier Intelligence Gathering Skills, Carlos Wiley
Assessment Of The Contribution Of Game-Based Simulation In The Advancement Of Individual Soldier Intelligence Gathering Skills, Carlos Wiley
Electronic Theses and Dissertations
Self-directed Learning Internet Modules based on gaming technology are making tremendous strides as tools to current training system for our military services. Currently, the US Army is testing the Every Soldier is a Sensor Simulation software (ES3) as part of the Every Soldiers a Sensor program that focuses on intelligence gathering and maintaining situational awareness. The primary training goal of this simulation is the training of individual soldiers on conducting "Active Surveillance" and "Threat Indicator Identification" where the soldier is an active participant in the process. Traditional training in intelligence gathering is based largely on cold war models. As a …
A Comparison And Evaluation Of Common Pid Tuning Methods, Justin Youney
A Comparison And Evaluation Of Common Pid Tuning Methods, Justin Youney
Electronic Theses and Dissertations
The motivation behind this thesis is to consolidate and evaluate the most common Proportional Integral Derivative (PID) controller tuning techniques used in industry. These are the tuning techniques used when the plant transfer function is not known. Many of these systems are poorly tuned because such consolidated information is not easily found in one single source such as this thesis. Once one of the tuning methods are applied almost always there will be further fine tuning needed to bring the system into the required design criteria. The purpose here is to find out which tuning technique will yield the lowest …
Augmentation In Visual Reality (Avr), Yunjun Zhang
Augmentation In Visual Reality (Avr), Yunjun Zhang
Electronic Theses and Dissertations
Human eyes, as the organs for sensing light and processing visual information, enable us to see the real world. Though invaluable, they give us no way to "edit" the received visual stream or to "switch" to a different channel. The invention of motion pictures and computer technologies in the last century enables us to add an extra layer of modifications between the real world and our eyes. There are two major approaches to modifications that we consider here, offline augmentation and online augmentation. The movie industry has pushed offline augmentation to an extreme level; audiences can experience visual surprises that …
Biostability In Drinking Water Distribution Systems In A Changing Water Quality Environment Using Corrosion Inhibitors, Bingjie Zhao
Biostability In Drinking Water Distribution Systems In A Changing Water Quality Environment Using Corrosion Inhibitors, Bingjie Zhao
Electronic Theses and Dissertations
In this study, the bacterial growth dynamics of 14 pilot drinking water distribution systems were studied in order to observe water quality changes due to corrosion inhibitor addition. Empirical models were developed to quantity the effect of inhibitor type and dose on bacterial growth (biofilm and bulk water). Water and pipe coupon samples were taken and examined during the experiments. The coupons were exposed to drinking water at approximately 20°C for at least 5 weeks to allow the formation of a measurable quasi- steady-state biofilm. Bulk water samples were taken every week. In this study, two simple but practical empirical …
An Analysis Of Misclassification Rates For Decision Trees, Mingyu Zhong
An Analysis Of Misclassification Rates For Decision Trees, Mingyu Zhong
Electronic Theses and Dissertations
The decision tree is a well-known methodology for classification and regression. In this dissertation, we focus on the minimization of the misclassification rate for decision tree classifiers. We derive the necessary equations that provide the optimal tree prediction, the estimated risk of the tree's prediction, and the reliability of the tree's risk estimation. We carry out an extensive analysis of the application of Lidstone's law of succession for the estimation of the class probabilities. In contrast to existing research, we not only compute the expected values of the risks but also calculate the corresponding reliability of the risk (measured by …
Magnetics Design For High Current Low Voltage Dc/Dc Converter, Hua Zhou
Magnetics Design For High Current Low Voltage Dc/Dc Converter, Hua Zhou
Electronic Theses and Dissertations
With the increasing demand for small and cost efficient DC/DC converters, the power converters are expected to operate with high efficiency. Magnetics components design is one of the biggest challenges in achieving the higher power density and higher efficiency due to the significant portion of magnetics components volume in the whole power system. At the same time, most of the experimental phenomena are related to the magnetics components. So, good magnetics components design is one of the key issues to implement low voltage high current DC/DC converter. Planar technology has many advantages. It has low profile construction, low leakage inductance …
Optimization Of Zonal Wavefront Estimation And Curvature Measurements, Weiyao Zou
Optimization Of Zonal Wavefront Estimation And Curvature Measurements, Weiyao Zou
Electronic Theses and Dissertations
Optical testing in adverse environments, ophthalmology and applications where characterization by curvature is leveraged all have a common goal: accurately estimate wavefront shape. This dissertation investigates wavefront sensing techniques as applied to optical testing based on gradient and curvature measurements. Wavefront sensing involves the ability to accurately estimate shape over any aperture geometry, which requires establishing a sampling grid and estimation scheme, quantifying estimation errors caused by measurement noise propagation, and designing an instrument with sufficient accuracy and sensitivity for the application. Starting with gradient-based wavefront sensing, a zonal least-squares wavefront estimation algorithm for any irregular pupil shape and size …
Entire Load Efficiency And Dynamic Performance Improvements For Dc-Dc Converters, Osama Abdel-Rahman
Entire Load Efficiency And Dynamic Performance Improvements For Dc-Dc Converters, Osama Abdel-Rahman
Electronic Theses and Dissertations
The scope of this work can be summarized by three main aspects of DC-DC power converters. The first aspect is soft switching topologies to improve conversion efficiency for On-Board Converters or Point of load (POL) converters, the second aspect is load adaptive control techniques to improve all load efficiency for battery powered DC-DC converters that are applied to mobile devices, and the third aspect is dynamic performance improvement techniques to improve load transient in voltage regulators. Topologies and control techniques for DC-DC converters are presented after reviewing loads powering requirements and steady-state and transients design challenges.