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2012

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Articles 4921 - 4950 of 6303

Full-Text Articles in Engineering

Simulation Of A Capacitive Micromachined Ultrasonic Transducer With A Parylene Membrane And Graphene Electrodes, David Sadat Jan 2012

Simulation Of A Capacitive Micromachined Ultrasonic Transducer With A Parylene Membrane And Graphene Electrodes, David Sadat

Electronic Theses and Dissertations

Medical ultrasound technology accounts for over half of all imaging tests performed worldwide. In comparison to other methods, ultrasonic imaging is more portable and lower cost, and is becoming more accessible to remote regions where traditionally no medical imaging can be done. However, conventional ultrasonic imaging systems still rely on expensive PZT-based ultrasound probes that limit broader applications. In addition, the resolution of PZT based transducers is low due to the limitation in hand-fabrication methods of the piezoelectric ceramics. Capacitive Micromachined Ultrasonic Transducers (CMUTs) appears as an alternative to the piezoelectric (PZT) ceramic based transducer for ultrasound medical imaging. CMUTs …

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Towards Evolving More Brain-Like Artificial Neural Networks, Sebastian Risi Jan 2012

Towards Evolving More Brain-Like Artificial Neural Networks, Sebastian Risi

Electronic Theses and Dissertations

An ambitious long-term goal for neuroevolution, which studies how artificial evolutionary processes can be driven to produce brain-like structures, is to evolve neurocontrollers with a high density of neurons and connections that can adapt and learn from past experience. Yet while neuroevolution has produced successful results in a variety of domains, the scale of natural brains remains far beyond reach. In this dissertation two extensions to the recently introduced Hypercube-based NeuroEvolution of Augmenting Topologies (HyperNEAT) approach are presented that are a step towards more brain-like artificial neural networks (ANNs). First, HyperNEAT is extended to evolve plastic ANNs that can learn …

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Brightness Temperature Calibration Of Sac-D/Aquarius Microwave Radiometer (Mwr), Sayak Krishna Biswas Jan 2012

Brightness Temperature Calibration Of Sac-D/Aquarius Microwave Radiometer (Mwr), Sayak Krishna Biswas

Electronic Theses and Dissertations

The Aquarius/SAC-D joint international science mission, between the National Aeronautics and Space Administration (NASA) of United States and the Argentine Space Agency (Comision Nacional de Actividades Espaciales, CONAE), was launched on a polarorbiting satellite on June 10, 2011. This mission of discovery will provide measurements of the global sea surface salinity, which contributes to understanding climatic changes in the global water cycle and how these variations influence the general ocean circulation. The Microwave Radiometer (MWR), a three channel Dicke radiometer operating at 23.8 GHz H-Pol and 36.5 GHz V-& H-Pol provided by CONAE, will complement Aquarius (NASA’s L-band radiometer/scatterometer) by …

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Setpad: A Sketch-Based Tool For Exploring Discrete Math Set Problems, Travis Cossairt Jan 2012

Setpad: A Sketch-Based Tool For Exploring Discrete Math Set Problems, Travis Cossairt

Electronic Theses and Dissertations

We present SetPad, a new application prototype that lets computer science students explore discrete math problems by sketching set expressions using pen-based input. Students can manipulate the expressions interactively with the tool via pen or multi-touch interface. Likewise, discrete mathematics instructors can use SetPad to display and work through set problems via a projector to better demonstrate the solutions to the students. We discuss the implementation and feature set of the application, as well as results from both an informal perceived usefulness evaluation for students taking a computer science foundation exam in addition to a formal user study measuring the …

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Fate Of Coated Zinc Oxide In Municipal Solid Waste Landfills, Stephanie Carbone Bolyard Jan 2012

Fate Of Coated Zinc Oxide In Municipal Solid Waste Landfills, Stephanie Carbone Bolyard

Electronic Theses and Dissertations

Given the increase in nanomaterial (NM) use in consumer products and the large fraction of waste placed in landfills worldwide, the probability of these products reaching municipal solid waste (MSW) landfills at the end of their useful life is high. Since nanotechnology use is still in its early stages, there are currently no regulations pertaining to the disposal of NMs and their fate in MSW landfills is still unknown. Understanding the fate of NMs in MSW landfills is vital to ensure the proper handling of these novel materials from cradle to grave; such research will provide information on how these …

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Structure And Properties Of Polymer-Derived Sibcn Ceramics, Yaohan Chen Jan 2012

Structure And Properties Of Polymer-Derived Sibcn Ceramics, Yaohan Chen

Electronic Theses and Dissertations

Polymer-derived ceramics (PDCs) are a unique class of multifunctional materials synthesized by thermal decomposition of polymeric precursors. Due to their unique and excellent properties and flexible manufacturing capability, PDC is a promising technology to prepare ceramic fibers, coatings, composites and micro-sensors for high-temperature applications. However, the structure-property relationships of PDCs have not been well understood. The lack of such understandings drastically limited the further developments and applications of the materials. In this dissertation, the structure and properties of amorphous polymer-derived silicon carbonitride (SiCN) and silicoboron carbonitride (SiBCN) have been studied. The SiCN was obtained using commercially available polysilazane as pre-ceramic …

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Networking And Security Solutions For Vanet Initial Deployment Stage, Baber Aslam Jan 2012

Networking And Security Solutions For Vanet Initial Deployment Stage, Baber Aslam

Electronic Theses and Dissertations

Vehicular ad hoc network (VANET) is a special case of mobile networks, where vehicles equipped with computing/communicating devices (called "smart vehicles") are the mobile wireless nodes. However, the movement pattern of these mobile wireless nodes is no more random, as in case of mobile networks, rather it is restricted to roads and streets. Vehicular networks have hybrid architecture; it is a combination of both infrastructure and infrastructure-less architectures. The direct vehicle to vehicle (V2V) communication is infrastructure-less or ad hoc in nature. Here the vehicles traveling within communication range of each other form an ad hoc network. On the other …

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Developing Surface Engineered Liquid Crystal Droplets For Sensing Applications, Tanmay Bera Jan 2012

Developing Surface Engineered Liquid Crystal Droplets For Sensing Applications, Tanmay Bera

Electronic Theses and Dissertations

Diagnosis plays a very crucial role in medicine and health care, which makes biosensors extremely important in modern technological context. Till date, various types of biosensors have been developed that are capable of detecting a wide range of biologically important species with great sensitivity and selectivity. However, most of these sensing units require highly sophisticated instrumentation and often lack the desired portability. Liquid crystal (LC) droplets, on the other hand, are a new type of functional material that are finding increasing research attention as a new sensing unit due to their tunable optical property, high surface area, portability and cost-effectiveness. …

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Modeling Annual Water Balance In The Seasonal Budyko Framework, Negin Alimohammadi Jan 2012

Modeling Annual Water Balance In The Seasonal Budyko Framework, Negin Alimohammadi

Electronic Theses and Dissertations

In this thesis, the role of soil water storage change on the annual water balance is evaluated based on observations at a large number of watersheds located in a spectrum of climate regions, and an annual water balance model is developed at the seasonal scale based on Budyko hypthesis. The annual water storage change is quantified based on water balance closure given the available data of precipitation, runoff, and evaporation estimated from remote sensing data and meteorology reanalysis. The responses of annual runoff, evaporation, and storage change to the interannual variability of precipitation and potential evaporation are then analyzed. Both …

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Investigation Of Tactile Displays For Robot To Human Communication, Daniel Barber Jan 2012

Investigation Of Tactile Displays For Robot To Human Communication, Daniel Barber

Electronic Theses and Dissertations

Improvements in autonomous systems technology and a growing demand within military operations are spurring a revolution in Human-Robot Interaction (HRI). These mixed-initiative human-robot teams are enabled by Multi-Modal Communication (MMC), which supports redundancy and levels of communication that are more robust than single mode interaction. (Bischoff & Graefe, 2002; Partan & Marler, 1999). Tactile communication via vibrotactile displays is an emerging technology, potentially beneficial to advancing HRI. Incorporation of tactile displays within MMC requires developing messages equivalent in communication power to speech and visual signals used in the military. Toward that end, two experiments were performed to investigate the feasibility …

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An Assessment Of Ecological Processes In The Apalachicola Estuarine System, Florida, Daina Smar Jan 2012

An Assessment Of Ecological Processes In The Apalachicola Estuarine System, Florida, Daina Smar

Electronic Theses and Dissertations

The following is a compilation of field data collected in 2011 and 2012 in Apalachicola, FL as part of a five year study assessing the ecological effects of sea level rise in the northern Gulf of Mexico. Many coastal communities, both natural and developed, will soon be working to mitigate the effects of sea level rise, if they are not already doing so. This thesis investigates the natural patterns of the Apalachicola estuarine system through the collection and analysis of in situ water, sediment, and biomass samples. Additionally, results of the field samples are presented and recommendations for additional sampling …

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Experimental Study And Modeling Of Mechanical Micro-Machining Of Particle Reinforced Heterogeneous Materials, Jian Liu Jan 2012

Experimental Study And Modeling Of Mechanical Micro-Machining Of Particle Reinforced Heterogeneous Materials, Jian Liu

Electronic Theses and Dissertations

This study focuses on developing explicit analytical and numerical process models for mechanical micro-machining of heterogeneous materials. These models are used to select suitable process parameters for preparing and micro-machining of these advanced materials. The material system studied in this research is Magnesium Metal Matrix Composites (Mg-MMCs) reinforced with nano-sized and micro-sized silicon carbide (SiC) particles. This research is motivated by increasing demands of miniaturized components with high mechanical performance in various industries. Mg-MMCs become one of the best candidates due to its light weight, high strength, and high creep/wear resistance. However, the improved strength and abrasive nature of the …

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Algorithms For Rendering Optimization, Jared Johnson Jan 2012

Algorithms For Rendering Optimization, Jared Johnson

Electronic Theses and Dissertations

This dissertation explores algorithms for rendering optimization realizable within a modern, complex rendering engine. The first part contains optimized rendering algorithms for ray tracing. Ray tracing algorithms typically provide properties of simplicity and robustness that are highly desirable in computer graphics. We offer several novel contributions to the problem of interactive ray tracing of complex lighting environments. We focus on the problem of maintaining interactivity as both geometric and lighting complexity grows without effecting the simplicity or robustness of ray tracing. First, we present a new algorithm called occlusion caching for accelerating the calculation of direct lighting from many light …

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Aerodynamic Characteristics Of A Gas Turbine Exhaust Diffuser With An Accompanying Exhaust Collection System, Bryan Bernier Jan 2012

Aerodynamic Characteristics Of A Gas Turbine Exhaust Diffuser With An Accompanying Exhaust Collection System, Bryan Bernier

Electronic Theses and Dissertations

The effects of an industrial gas turbine’s Exhaust Collector Box (ECB) geometry on static pressure recovery and total pressure loss were investigated in this study experimentally and computationally. This study aims to further understand how exit boundary conditions affect the performance of a diffuser system as well as the accuracy of industry standard computational models. A design of experiments approach was taken using a Box-Behnken design method for investigating three geometric parameters of the ECB. In this investigation, the exhaust diffuser remained constant through each test, with only the ECB being varied. A system performance analysis was conducted for each …

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Risk Management In Reservoir Operations In The Context Of Undefined Competitive Consumption, Yunus Salami Jan 2012

Risk Management In Reservoir Operations In The Context Of Undefined Competitive Consumption, Yunus Salami

Electronic Theses and Dissertations

Dams and reservoirs with multiple purposes require effective management to fully realize their purposes and maximize efficiency. For instance, a reservoir intended mainly for the purposes of flood control and hydropower generation may result in a system with primary objectives that conflict with each other. This is because higher hydraulic heads are required to achieve the hydropower generation objective while relatively lower reservoir levels are required to fulfill flood control objectives. Protracted imbalances between these two could increase the susceptibility of the system to risks of water shortage or flood, depending on inflow volumes and operational policy effectiveness. The magnitudes …

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Computational Methods For Analyzing Rna Folding Landscapes And Its Applications, Yuan Li Jan 2012

Computational Methods For Analyzing Rna Folding Landscapes And Its Applications, Yuan Li

Electronic Theses and Dissertations

Non-protein-coding RNAs play critical regulatory roles in cellular life. Many ncRNAs fold into specific structures in order to perform their biological functions. Some of the RNAs, such as riboswitches, can even fold into alternative structural conformations in order to participate in different biological processes. In addition, these RNAs can transit dynamically between different functional structures along folding pathways on their energy landscapes. These alternative functional structures are usually energetically favored and are stable in their local energy landscapes. Moreover, conformational transitions between any pair of alternate structures usually involve high energy barriers, such that RNAs can become kinetically trapped by …

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High Performance Low Voltage Power Mosfet For High-Frequency Synchronous Buck Converters, Boyi Yang Jan 2012

High Performance Low Voltage Power Mosfet For High-Frequency Synchronous Buck Converters, Boyi Yang

Electronic Theses and Dissertations

Power management solutions such as voltage regulator (VR) mandate DC-DC converters with high power density, high switching frequency and high efficiency to meet the needs of future computers and telecom equipment. The trend towards DC-DC converters with higher switching frequency presents significant challenges to power MOSFET technology. Optimization of the MOSFETs plays an important role in improving low-voltage DC-DC converter performance. This dissertation focuses on developing and optimizing high performance low voltage power MOSFETs for high frequency applications. With an inherently large gate charge, the trench MOSFET suffers significant switching power losses and cannot continue to provide sufficient performance in …

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Systems Analysis For Urban Water Infrastructure Expansion With Global Change Impact Under Uncertainties, Cheng Qi Jan 2012

Systems Analysis For Urban Water Infrastructure Expansion With Global Change Impact Under Uncertainties, Cheng Qi

Electronic Theses and Dissertations

Over the past decades, cost-effectiveness principle or cost-benefit analysis has been employed oftentimes as a typical assessment tool for the expansion of drinking water utility. With changing public awareness of the inherent linkages between climate change, population growth and economic development, the addition of global change impact in the assessment regime has altered the landscape of traditional evaluation matrix. Nowadays, urban drinking water infrastructure requires careful long-term expansion planning to reduce the risk from global change impact with respect to greenhouse gas (GHG) emissions, economic boom and recession, as well as water demand variation associated with population growth and migration. …

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A Retrospective Analysis And Field Study Of Nanotechnology Related Ergonomic Risk In Industries Utilizing Nanomaterials, Wanda Greaves-Holmes Jan 2012

A Retrospective Analysis And Field Study Of Nanotechnology Related Ergonomic Risk In Industries Utilizing Nanomaterials, Wanda Greaves-Holmes

Electronic Theses and Dissertations

The National Science Foundation estimates that two million skilled nanotechnology workers will be needed world wide by 2015 – one million of them in the United States (2001). In the absence of scientific clarity about the potential health effects of occupational exposure to nanoparticles, guidance in decision making about hazards, risk, and controls takes on new importance. Currently, guiding principles on personal protective equipment for workers who come in contact with nanomaterials have not been standardized universally. Utilizing the NASATLX, this dissertation investigates the adequacy and shortcomings of research efforts that seek to determine whether or not occupational exposure to …

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Design, Characterization And Analysis Of Electrostatic Discharge (Esd) Protection Solutions In Emerging And Modern Technologies, Wen Liu Jan 2012

Design, Characterization And Analysis Of Electrostatic Discharge (Esd) Protection Solutions In Emerging And Modern Technologies, Wen Liu

Electronic Theses and Dissertations

Electrostatic Discharge (ESD) is a significant hazard to electronic components and systems. Based on a specific processing technology, a given circuit application requires a customized ESD consideration that includes the devices’ operating voltage, leakage current, breakdown constraints, and footprint. As new technology nodes mature every 3-5 years, design of effective ESD protection solutions has become more and more challenging due to the narrowed design window, elevated electric field and current density, as well as new failure mechanisms that are not well understood. The endeavor of this research is to develop novel, effective and robust ESD protection solutions for both emerging …

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Evaporation, Precipitation Dynamics And Instability Of Acoustically Levitated Functional Droplets, Abhishek Saha Jan 2012

Evaporation, Precipitation Dynamics And Instability Of Acoustically Levitated Functional Droplets, Abhishek Saha

Electronic Theses and Dissertations

Evaporation of pure and binary liquid droplets is of interest in thermal sprays and spray drying of food, ceramics and pharmaceutical products. Understanding the rate of heat and mass transfer in any drying process is important not only to enhance evaporation rate or vapor-gas mixing, but also to predict and control the final morphology and microstructure of the precipitates. Acoustic levitation is an alternative method to study micron-sized droplets without wall effects, which eliminates chemical and thermal contamination with surfaces. This work uses an ultrasonic levitation technique to investigate the vaporization dynamics under radiative heating, with focus on evaporation characteristics, …

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Coupled Usage Of Discrete Hole And Transpired Film For Better Cooling Performance, Michael Torrance Jan 2012

Coupled Usage Of Discrete Hole And Transpired Film For Better Cooling Performance, Michael Torrance

Electronic Theses and Dissertations

Electricity has become so ingrained in everyday life that the current generation has no knowledge of life without it. The majority of power generation in the United States is the result of turbines of some form. With such widespread utilization of these complex rotating machines, any increase in efficiency translates into improvements in the current cost of energy. These improvements manifest themselves as reductions in greenhouse emissions or possible savings to the consumer. The most important temperature regarding turbine performance is the temperature of the hot gas entering the turbine, denoted turbine inlet temperature. Increasing the turbine inlet temperature allows …

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Biogeochemical Cycling And Nutrient Control Strategies For Groundwater At Stormwater Infiltration Basins, Andrew M. O'Reilly Jan 2012

Biogeochemical Cycling And Nutrient Control Strategies For Groundwater At Stormwater Infiltration Basins, Andrew M. O'Reilly

Electronic Theses and Dissertations

Elevated concentrations of nutrients, particularly nitrate, in groundwater and springs in Florida are a growing resource management concern. Stormwater infiltration basins, which are a common stormwater management practice in the well-drained karst terrain areas of Florida, are a potentially important source of nutrients to the groundwater system because stormwater exits the basin by only evaporation or infiltration. To better understand the biogeochemical processes integrating stormwater infiltration impacts on groundwater resources in a field-scale setting, a combination of hydrologic, soil chemistry, water chemistry, dissolved and soil gas, isotope, and microbiological data was collected from 2007 through 2010 at two stormwater infiltration …

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Microscopic Assessment Of Transportation Emissions On Limited Access Highways, Hatem Abou-Senna Jan 2012

Microscopic Assessment Of Transportation Emissions On Limited Access Highways, Hatem Abou-Senna

Electronic Theses and Dissertations

On-road vehicles are a major source of transportation carbon dioxide (CO2) greenhouse gas emissions in all the developed countries, and in many of the developing countries in the world. Similarly, several criteria air pollutants are associated with transportation, e.g., carbon monoxide (CO), nitrogen oxides (NOx), and particulate matter (PM). The need to accurately quantify transportation-related emissions from vehicles is essential. Transportation agencies and researchers in the past have estimated emissions using one average speed and volume on a long stretch of roadway. With MOVES, there is an opportunity for higher precision and accuracy. Integrating a microscopic traffic simulation model (such …

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A Microwave Radiometer Roughness Correction Algorithm For Sea Surface Salinity Retrieval, Yazan Henry Hejazin Jan 2012

A Microwave Radiometer Roughness Correction Algorithm For Sea Surface Salinity Retrieval, Yazan Henry Hejazin

Electronic Theses and Dissertations

The Aquarius/SAC-D is an Earth Science remote sensing satellite mission to measure global Sea Surface Salinity (SSS) that is sponsored by the NASA and the Argentine Space Agency (CONAE). The prime remote sensor is the Aquarius (AQ) L-band radiometer/scatterometer, which measures the L-band emitted blackbody radiation (brightness temperature) from the ocean. The brightness temperature at L-band is proportional to the ocean salinity as well as a number of physical parameters including ocean surface wind speed. The salinity retrieval algorithm make corrections for all other parameters before retrieving salinity, and the greatest of these is the increased brightness temperature due to …

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Detecting, Tracking, And Recognizing Activities In Aerial Video, Vladimir Reilly Jan 2012

Detecting, Tracking, And Recognizing Activities In Aerial Video, Vladimir Reilly

Electronic Theses and Dissertations

In this dissertation, we address the problem of detecting humans and vehicles, tracking them in crowded scenes, and finally determining their activities in aerial video. Even though this is a well explored problem in the field of computer vision, many challenges still remain when one is presented with realistic data. These challenges include large camera motion, strong scene parallax, fast object motion, large object density, strong shadows, and insufficiently large action datasets. Therefore, we propose a number of novel methods based on exploiting scene constraints from the imagery itself to aid in the detection and tracking of objects. We show, …

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Optimization Of Process Parameters For Faster Deposition Of Cuin1-Xgaxs2 And Cuin1-Xgaxse2-Ysy Thin Film Solar Cells, Ashwani Kaul Jan 2012

Optimization Of Process Parameters For Faster Deposition Of Cuin1-Xgaxs2 And Cuin1-Xgaxse2-Ysy Thin Film Solar Cells, Ashwani Kaul

Electronic Theses and Dissertations

Thin film solar cells have the potential to be an important contributor to the world energy demand in the 21st century. Among all the thin film technologies, CuInGaSe2 (CIGS) thin film solar cells have achieved the highest efficiency. However, the high price of photovoltaic (PV) modules has been a major factor impeding their growth for terrestrial applications. Reduction in cost of PV modules can be realized by several ways including choosing scalable processes amenable to large area deposition, reduction in the materials consumption of active layers, and attaining faster deposition rates suitable for in-line processing. Selenization-sulfurization of sputtered metallic Cu-In-Ga …

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Complex-Valued Adaptive Digital Signal Enhancement For Applications In Wireless Communication Systems, Ying Liu Jan 2012

Complex-Valued Adaptive Digital Signal Enhancement For Applications In Wireless Communication Systems, Ying Liu

Electronic Theses and Dissertations

In recent decades, the wireless communication industry has attracted a great deal of research efforts to satisfy rigorous performance requirements and preserve high spectral efficiency. Along with this trend, I/Q modulation is frequently applied in modern wireless communications to develop high performance and high data rate systems. This has necessitated the need for applying efficient complex-valued signal processing techniques to highly-integrated, multi-standard receiver devices. In this dissertation, novel techniques for complex-valued digital signal enhancement are presented and analyzed for various applications in wireless communications. The first technique is a unified block processing approach to generate the complex-valued conjugate gradient Least …

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Application And Optimization Of Membrane Processes Treating Brackish And Surficial Groundwater For Potable Water Production, Jayapregasham Tharamapalan Jan 2012

Application And Optimization Of Membrane Processes Treating Brackish And Surficial Groundwater For Potable Water Production, Jayapregasham Tharamapalan

Electronic Theses and Dissertations

The research presented in this dissertation provides the results of a comprehensive assessment of the water treatment requirements for the City of Sarasota. The City’s drinking water supply originates from two sources: (1) brackish groundwater from the Downtown well field, and (2) Floridan surficial groundwater from the City’s Verna well field. At the time the study was initiated, the City treated the brackish water supply using a reverse osmosis process that relied on sulfuric acid for pH adjustment as a pretreatment method. The Verna supply was aerated at the well field before transfer to the City’s water treatment facility, either …

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Effluent Water Quality Improvement Using Silt Fences And Stormwater Harvesting, Ikiensinma Gogo-Abite Jan 2012

Effluent Water Quality Improvement Using Silt Fences And Stormwater Harvesting, Ikiensinma Gogo-Abite

Electronic Theses and Dissertations

Construction sites are among the most common areas to experience soil erosion and sediment transport due to the mandatory foundation tasks such as excavation and land grubbing. Thus, temporary sediment barriers are installed along the perimeter to prevent sediment transport from the site. Erosion and sediment transport control measures may include, but not limited to, physical and chemical processes such as the use of a silt fence and polyacrylamide product. Runoff from construction sites and other impervious surfaces are routinely discharged into ponds for treatment before being released into a receiving water body. Stormwater harvesting from a pond for irrigation …

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