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Articles 3481 - 3510 of 4180
Full-Text Articles in Engineering
An Investigation Of Size Exclusion And Diffusion Controlled Membrane Fouling, Colin Michael Hobbs
An Investigation Of Size Exclusion And Diffusion Controlled Membrane Fouling, Colin Michael Hobbs
Electronic Theses and Dissertations
The reduction of membrane productivity (i.e. membrane fouling) during operation occurs in virtually all membrane applications. Membrane fouling originates from the method by which membranes operate: contaminants are rejected by the membrane and retained on the feed side of the membrane while treated water passes through the membrane. The accumulation of these contaminants on the feed side of the membrane results in increased operating pressures, increased backwashing frequencies, increased chemical cleaning frequencies, and increased membrane replacement frequencies. The most significant practical implication of membrane fouling is increased operating and maintenance costs. As such, membrane fouling must be properly managed to …
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.
Lattice Boltzmann Simulation To Study Single And Multi Bubble Dynamics, Amit Gupta
Lattice Boltzmann Simulation To Study Single And Multi Bubble Dynamics, Amit Gupta
Electronic Theses and Dissertations
In recent years, the lattice Boltzmann method (LBM) has emerged as a powerful tool that has replaced conventional macroscopic techniques like Computational Fluid Dynamics (CFD) in many applications. The LBM starts from meso- and microscopic Boltzmann's kinetic equation to determine macroscopic fluid dynamics. The origins of LBM can be drawn back to lattice gas cellular automata (LGCA); however it lacks Galilean invariance and creates statistical noise in the system. LBM on the other hand does away from these drawbacks of LGCA, and is easy to implement in complex geometries and can be used to study microscopic flow behavior in complex …
Buffer Techniques For Stochastic Resource Constrained Project Scheduling With Stochastic Task Insertions Problems, Jennifer Grey
Buffer Techniques For Stochastic Resource Constrained Project Scheduling With Stochastic Task Insertions Problems, Jennifer Grey
Electronic Theses and Dissertations
Project managers are faced with the challenging task of managing an environment filled with uncertainties that may lead to multiple disruptions during project execution. In particular, they are frequently confronted with planning for routine and non-routine unplanned work: known, identified, tasks that may or may not occur depending upon various, often unpredictable, factors. This problem is known as the stochastic task insertion problem, where tasks of deterministic duration occur stochastically. Traditionally, project managers may include an extra margin within deterministic task times or an extra time buffer may be allotted at the end of the project schedule to protect the …
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 …
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 …
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 …
High Current Density Low Voltage Isolated Dc-Dc Converterswith Fast Transient Response, Liangbin Yao
High Current Density Low Voltage Isolated Dc-Dc Converterswith Fast Transient Response, Liangbin Yao
Electronic Theses and Dissertations
With the rapid development of microprocessor and semiconductor technology, industry continues to update the requirements for power supplies. For telecommunication and computing system applications, power supplies require increasing current level while the supply voltage keeps decreasing. For example, the Intel's CPU core voltage decreased from 2 volt in 1999 to 1 volt in 2005 while the supply current increased from 20A in 1999 to up to 100A in 2005. As a result, low-voltage high-current high efficiency dc-dc converters with high power-density are demanded for state-of-the-art applications and also the future applications. Half-bridge dc-dc converter with current-doubler rectification is regarded as …
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 …
Self-Assembled Lipid Tubules: Structures, Mechanical Properties, And Applications., Yue Zhao
Self-Assembled Lipid Tubules: Structures, Mechanical Properties, And Applications., Yue Zhao
Electronic Theses and Dissertations
Self-assembled lipid tubules are particularly attractive for inorganic synthesis and drug delivery because they have hollow cylindrical shapes and relatively rigid mechanical properties. In this thesis work, we have synthesized lipid tubules of 1,2-bis(tricosa-10,12-dinoyl)-sn-glycero-3-phosphocholine (DC8,9PC) by self-assembly and polymerization in solutions. We demonstrate for the first time that both uniform and modulated molecular tilt orderings exist in the tubule walls, which have been predicted by current theories, and therefore provide valuable supporting evidences for self-assembly mechanisms of chiral molecules. Two novel methods are developed for studying the axial and radial deformations of DC8,9PC lipid tubules. Mechanical properties of DC8,9PC tubules …
Bluetooth-Base Worm Modeling And Simulation, Haiou Xiang
Bluetooth-Base Worm Modeling And Simulation, Haiou Xiang
Electronic Theses and Dissertations
Bluetooth is one of the most popular technologies in the world in the new century. Meanwhile it attracts attackers to develop new worm and malicious code attacking Bluetooth wireless network. So far the growth of mobile malicious code is very fast and they have become a great potential threat to our society. In this thesis, we study Bluetooth worm in Mobile Wireless Network. Firstly we investigate the Bluetooth technology and several previously appeared Bluetooth worms, e.g. "Caribe","Comwar", and we find the infection cycle of a Bluetooth worm. Next, we develop a new simulator, Bluetooth Worm simulator (BTWS), which simulates Bluetooth …
Efficient Algorithms For Correlation Pattern Recognition, Pradeep Ragothaman
Efficient Algorithms For Correlation Pattern Recognition, Pradeep Ragothaman
Electronic Theses and Dissertations
The mathematical operation of correlation is a very simple concept, yet has a very rich history of application in a variety of engineering fields. It is essentially nothing but a technique to measure if and to what degree two signals match each other. Since this is a very basic and universal task in a wide variety of fields such as signal processing, communications, computer vision etc., it has been an important tool. The field of pattern recognition often deals with the task of analyzing signals or useful information from signals and classifying them into classes. Very often, these classes are …
The Nature Of Turbulence In A Narrow Apex Angle Isosceles Triangular Duct, Vaidyanathan Krishnan
The Nature Of Turbulence In A Narrow Apex Angle Isosceles Triangular Duct, Vaidyanathan Krishnan
Electronic Theses and Dissertations
An experimental investigation was performed to ascertain the nature of turbulence in a narrow apex angle isosceles triangular duct. The study involved the design and construction of a low noise, low turbulence wind tunnel that had an isosceles triangular test section with an apex angle of 11.5[degrees]. Experiments involved the measurement of velocity fluctuations using hot wire anemometry and wall pressure fluctuations using a condenser microphone. Measurement of the velocity fluctuations reconfirms the coexistence of laminar and turbulent regions at a given cross section for a range of Reynolds numbers. The laminar region is concentrated closer to the apex while …
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 …
Zinc Cadmium Sulphide And Zinc Sulphide As Alternative Heterojunction Partners For Cigs2 Solar Cells, Bhaskar Kumar
Zinc Cadmium Sulphide And Zinc Sulphide As Alternative Heterojunction Partners For Cigs2 Solar Cells, Bhaskar Kumar
Electronic Theses and Dissertations
Devices with ZnCdS/ZnS heterojunction partner layer have shown better blue photon response due to higher band gap of these compounds as compared to devices with CdS heterojunction partner layer. CdS heterojunction partner layer has shown high photovoltaic conversion efficiencies with CIGS absorber layer while efficiencies are lower with CuIn1-xGaxS2 (CIGS2). A negative conduction band offset has been observed for CdS/CIGS2 as compared to near flat conduction band alignment in case of CdS/CIGS devices, which results in higher interface dominated recombination. Moreover, it has been predicted that optimum band offsets for higher efficiency solar cells may be achieved for cells with …
Graph Theoretic Modeling: Case Studies In Redundant Arrays Of Independent Disks And Network Defense, Sanjeeb Nanda
Graph Theoretic Modeling: Case Studies In Redundant Arrays Of Independent Disks And Network Defense, Sanjeeb Nanda
Electronic Theses and Dissertations
Graph theoretic modeling has served as an invaluable tool for solving a variety of problems since its introduction in Euler's paper on the Bridges of Königsberg in 1736 . Two amongst them of contemporary interest are the modeling of Redundant Arrays of Inexpensive Disks (RAID), and the identification of network attacks. While the former is vital to the protection and uninterrupted availability of data, the latter is crucial to the integrity of systems comprising networks. Both are of practical importance due to the continuing growth of data and its demand at increasing numbers of geographically distributed locations through the use …
Evaluation Of The Amazon Rain Forest As A Distributed Target For Satellite Microwave Radiometer Calibration, Nishant Patel
Evaluation Of The Amazon Rain Forest As A Distributed Target For Satellite Microwave Radiometer Calibration, Nishant Patel
Electronic Theses and Dissertations
For over three decades, satellite radars have used the Amazon tropical rain forest as a stable homogeneous and isotropic scattering target for calibration. This thesis extends previous work to consider the use of the Amazon as a blackbody target for passive microwave inter-satellite calibration. The characterization of a natural target for radiometric calibration is a formidable task due to the difficulty in obtaining an absolute brightness temperature standard. Previously, multi-frequency microwave brightness temperatures measured by the Tropical Rainfall Measuring Mission Microwave Imager (TMI) were used to provide multi-year observations in local time windows. Our approach differs in that we will …
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 …
Coalition Formation And Teamwork In Embodied Agents, Majid Ali Khan
Coalition Formation And Teamwork In Embodied Agents, Majid Ali Khan
Electronic Theses and Dissertations
Embodied agents are agents acting in the physical world, such as persons, robots, unmanned air or ground vehicles and so on. These types of agents are subject to spatio-temporal constraints, which do not exist for agents acting in a virtual environment. The movement of embodied agents is limited by obstacles and maximum velocity, while their communication is limited by the transmission range of their wireless devices. This dissertation presents contributions to the techniques of coalition formation and teamwork coordination for embodied agents. We considered embodied agents in three different settings, each of them representative of a class of practical applications. …
Modeling, Design And Evaluation Of Networking Systems And Protocols Through Simulation, Daniel Jonathan Lacks
Modeling, Design And Evaluation Of Networking Systems And Protocols Through Simulation, Daniel Jonathan Lacks
Electronic Theses and Dissertations
Computer modeling and simulation is a practical way to design and test a system without actually having to build it. Simulation has many benefits which apply to many different domains: it reduces costs creating different prototypes for mechanical engineers, increases the safety of chemical engineers exposed to dangerous chemicals, speeds up the time to model physical reactions, and trains soldiers to prepare for battle. The motivation behind this work is to build a common software framework that can be used to create new networking simulators on top of an HLA-based federation for distributed simulation. The goals are to model and …
A Method Of Content-Based Image Retrieval For The Generation Of Image Mosaics, Michael Snead
A Method Of Content-Based Image Retrieval For The Generation Of Image Mosaics, Michael Snead
Electronic Theses and Dissertations
An image mosaic is an artistic work that uses a number of smaller images creatively combined together to form another larger image. Each building block image, or tessera, has its own distinctive and meaningful content, but when viewed from a distance the tesserae come together to form an aesthetically pleasing montage. This work presents the design and implementation of MosaiX, a computer software system that generates these image mosaics automatically. To control the image mosaic creation process, several parameters are used within the system. Each parameter affects the overall mosaic quality, as well as required processing time, in its own …
Extending Distributed Temporal Protocol Logic To A Proof Based Framework For Authentication Protocols, Shahabuddin Muhammad
Extending Distributed Temporal Protocol Logic To A Proof Based Framework For Authentication Protocols, Shahabuddin Muhammad
Electronic Theses and Dissertations
Running critical applications, such as e-commerce, in a distributed environment requires assurance of the identities of the participants communicating with each other. Providing such assurance in a distributed environment is a difficult task. The goal of a security protocol is to overcome the vulnerabilities of a distributed environment by providing a secure way to disseminate critical information into the network. However, designing a security protocol is itself an error-prone process. In addition to employing an authentication protocol, one also needs to make sure that the protocol successfully achieves its authentication goals. The Distributed Temporal Protocol Logic (DTPL) provides a language …
Redistribution Of Manganese Ion Implanted In Silicon, Arun Kumar Shunmugavelu
Redistribution Of Manganese Ion Implanted In Silicon, Arun Kumar Shunmugavelu
Electronic Theses and Dissertations
Ion implantation and the subsequent redistribution of manganese atoms in Czochralski Silicon (Cz-Si) and Floating Zone Silicon (Fz-Si) due to thermal annealing between 300 C and 1000 C is studied using Secondary Ion Mass Spectroscopy. The samples ion implanted at 340 C showed multiple peak formation above 900 C. This was not observed for the samples ion implanted at room temperature. Cz-Si and Fz-Si showed similar redistribution profiles.
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 …
Steady State And Dynamic Analysis And Optimization Of Single-Stage Power Factor Correction Converters, Khalid Rustom
Steady State And Dynamic Analysis And Optimization Of Single-Stage Power Factor Correction Converters, Khalid Rustom
Electronic Theses and Dissertations
With the increased interest in applying Power Factor Correction (PFC) to off-line AC-DC converters, the field of integrated, single-stage PFC converter development has attracted wide attention. Considering the tens of millions of low-to-medium power supplies manufactured each year for today's rechargeable equipment, the expected reduction in cost by utilizing advanced technologies is significant. To date, only a few single-stage topologies have made it to the market due to the inherit limitations in this structure. The high voltage and current stresses on the components led to reduced efficiency and an increased failure rate. In addition, the component prices tend to increase …
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 …
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 …
Methods Of Extrapolating Low Cycle Fatigue Data To High Stress Amplitudes, David Charles Radonovich
Methods Of Extrapolating Low Cycle Fatigue Data To High Stress Amplitudes, David Charles Radonovich
Electronic Theses and Dissertations
Modern gas turbine component design applies much effort into prediction and avoidance of fatigue. Advances in the prediction of low-cycle fatigue (LCF) cracks will reduce repair and replacement costs of turbine components. These cracks have the potential to cause component failure. Regression modeling of low-cycle fatigue (LCF)test data is typically restricted for use over the range of the test data. It is often difficult to characterize the plastic strain curve fit constants when the plastic strain is a small fraction of the total strain acquired. This is often the case with high strength, moderate ductility Ni-base superalloys. The intent of …
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 …