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Articles 2821 - 2850 of 3180

Full-Text Articles in Engineering

Combining The Wind Power Generation System With Energy Storage Equipments, Ming-Shun Lu Jan 2008

Combining The Wind Power Generation System With Energy Storage Equipments, Ming-Shun Lu

Electrical Engineering Theses - Archive

With the advance in wind turbine technologies, the cost of wind energy becomes competitive with other fuel-based generation resources. Due to the price hike of the fossil fuel and the concern of the global warming, the development of wind power has rapidly progressed over the last decade. The annual growth rate of the wind generation installation has exceeded 26% since 1990s. Many countries have set goal for high penetration levels of wind generations. Recently, several large-scale wind generation projects have been implemented all over the world. It is economically beneficial to integrate very large amounts of wind capacity in power …


Hybrid Video Coding Design With Variable Size Integer Transforms And Structural Similarity, Att Kruafak Jan 2008

Hybrid Video Coding Design With Variable Size Integer Transforms And Structural Similarity, Att Kruafak

Electrical Engineering Dissertations - Archive

This research proposes a block-based video codec design with two objectives. The first goal is to propose a method for intraframe that improves the rate-distortion (peak signal-to-noise ratio versus bit rate) of a fixed-size transform encoder. The proposed method uses three integer transform sizes (4x4), (8x8), and (16x16). The codec also adopts H.264-like spatial prediction to intraframe encoding. For simplicity of the design, Huffman variable-length code is used as entropy encoding. For intraframe encoding, the simulations show rate-distortion improvement over JPEG and JPEG2000. In some test sequences, the simulations also show improvement over H.264 (baseline profile at low complexity mode …


Complex Directional Wavelet Transforms: Representation, Statistical Modeling And Applications, An Phuoc Nhu Vo Jan 2008

Complex Directional Wavelet Transforms: Representation, Statistical Modeling And Applications, An Phuoc Nhu Vo

Electrical Engineering Dissertations - Archive

The thesis presents an new image decomposition for feature extraction, which is called the pyramidal dual-tree directional filter bank (PDTDFB). The image representation has an overcomplete ratio of less than 8/3 and uses a separable filter bank implementation structure. We discuss how to utilize both magnitude and phase information obtained from the PDTDFB for the purpose of texture image retrieval. The relative phase, which is the difference of phases between two adjacent complex coefficients, has a linear relationship with the angle of dominant orientation within a subband. This information is incorporated to form a new feature vector called CDFB-RP. Another …


Data Mining-Driven Approahces For Process Monitoring And Diagnosis, Thuntee Sukchotrat Jan 2008

Data Mining-Driven Approahces For Process Monitoring And Diagnosis, Thuntee Sukchotrat

Industrial, Manufacturing, and Systems Engineering Dissertations - Archive

The objective of this dissertation is to develop a new set of efficient process monitoring and diagnostic tools through their integration with data mining algorithms. Statistical process control (SPC) is one of the most widely used techniques for quality control. Although traditional SPC tools are effective in simple manufacturing processes that generate a small volume of independent data, these tools falter when confronted by the large streams of complex and correlated data found in modern manufacturing systems. As the limitations of SPC methodology become increasingly obvious in the face of ever more complex manufacturing processes, data mining, because of its …


The Thermal Effects Of Self Heating Of Transistors On Analog Amplifier Design And Evaluation, Kamal Ranjan Sinha Jan 2008

The Thermal Effects Of Self Heating Of Transistors On Analog Amplifier Design And Evaluation, Kamal Ranjan Sinha

Electrical Engineering Dissertations - Archive

Electrothermal effects play a major role in the performance of modern silicon-on-insulator (SOI) bipolar junction transistors (BJTs). This research work examines the influence of electrothermal feedback within a single device and within a circuit composed of such devices. Specifically, the frequency-domain thermal effects of self-heating in SOI BJTs on the performance of analog integrated circuits, with emphasis on current mirrors, and current-feedback operational amplifiers (CFOA), are investigated through analytical formulation, simulation, and measurement.For the extensive analysis and characterization of self-heating thermal effects, the Vertical Bipolar Inter-Company (VBIC) models for SOI BJTs are developed from fundamental physical device considerations. Extensive simulations …


Thermal Characterization Of Dielectrically Isolated Bipolar Junction Transistor, Daewoo Kim Jan 2008

Thermal Characterization Of Dielectrically Isolated Bipolar Junction Transistor, Daewoo Kim

Electrical Engineering Dissertations - Archive

Since the integrated circuit (IC) was invented in 1960, the operating speed of semiconductor devices has steadily increased and the number of semiconductor devices in an IC chip has grown by a size reduction of the devices. This trend has lead to the rapid increase of power consumption and heat generation. As a result of this increase, thermal characterization of semiconductor devices has become more important.It is especially important to consider thermal characteristics of the dielectrically isolated complementary bipolar junction transistor (DIBJT) which offers many advantages. However, a major disadvantage of this device is an increase in self-heating. Because the …


Functional Data Analysis For Environmental And Biomedical Problems, Chivalai Temiyasathit Jan 2008

Functional Data Analysis For Environmental And Biomedical Problems, Chivalai Temiyasathit

Industrial, Manufacturing, and Systems Engineering Dissertations - Archive

Vast amounts of data are being generated due to the development of sensing technology. Among those, one of the common types of data usually found in various discipline is the functional data. Because the functional data are generally collected in a wide area of interest over a relatively long period, such analyses should take into account both temporal and spatial characteristics. Furthermore, combinations of observations from multiple locations, each with a large number of serially correlated values, lead to a situation that poses a great challenge to analytical and computational capabilities. In contrast, data obtained from medical and biomedical researches …


Thermal Effects And Analysis On Analog Integrated Circuit Design, Ardasheir Sayek Rahman Jan 2008

Thermal Effects And Analysis On Analog Integrated Circuit Design, Ardasheir Sayek Rahman

Electrical Engineering Theses - Archive

Analog circuit design is an art of circuit designing. With technology becoming more advance and size of devices shrinking, circuit designing has becoming a real chance for the designers to meet up the demands in the market. Density of device transistor is rapidly increasing leading to thermal runaway issues and increasing operational speed of the transistors. Thus transistors are more sensitive to temperature changes, therefore requiring a more sensitive and accurate modeling of the thermal effects of the device as well as its adjacent devices. This research is on the thermal modeling of dielectric bipolar junction devices. It looks into …


Studies On Field Stabilization Methods To Prevent Surficial Slope Failures Of Earth Fill Dams, Venkata S. Dronamraju Jan 2008

Studies On Field Stabilization Methods To Prevent Surficial Slope Failures Of Earth Fill Dams, Venkata S. Dronamraju

Civil Engineering Dissertations - Archive

Surficial failures are occurring frequently on the slopes of earthfill dams which are predominantly rainfall induced. Desiccation cracks form on the slope surface during dry environment which accelerates infiltration during rainfall. Infiltration causes increase of pore water pressures and saturation of soil mass in top layer resulting in surficial failures. Numerous surficial failures occurred on the slope of earthfill dams maintained by The United States Army Corps. of Engineers. The current research is undertaken at the University of Texas at Arlington with an objective of exploring the best field stabilization method to mitigate these surficial failures.Two sites, Joe Pool Dam …


Combined Scalability Coding Based On The Scalable Extension Of H.264/Avc, Sangseok Park Jan 2008

Combined Scalability Coding Based On The Scalable Extension Of H.264/Avc, Sangseok Park

Electrical Engineering Dissertations - Archive

Fine-grain scalability (FGS) based on significant and refinement coding is one of the ways to achieve quality scalability by providing a graceful quality degradation through truncations of the FGS enhancement layer. This approach is useful for video conferencing and telephony on wireless networks, which need to ensure real-time and low-delay conditions since they are subject to serious bit rate fluctuations. The simplification of FGS is proposed to reduce the overall complexity for the Progressive Refinement (PR) slice. The one pass scanning structure is introduced to simplify the coding pass of the FGS layers and the code type method is also …


Visualizing The Flow Induced By An Air Curtain Over A Mannequin Using Stereo Particle Image Velocimetry, John Edward Fernandes Jan 2008

Visualizing The Flow Induced By An Air Curtain Over A Mannequin Using Stereo Particle Image Velocimetry, John Edward Fernandes

Mechanical and Aerospace Engineering Theses - Archive

Air curtains find widespread applications in today's world, such as in malls, supermarkets, airports, cold storage, etc., to allow easy pedestrian movement between two different environments. There is interest in understanding the flow induced by traffic through the air curtain in terms of energy efficiency and the ability to provide isolation from contaminants and airborne pathogens. To develop an understanding of the flow, an initial exploratory study was performed using a static mannequin. A stereo particle image velocimetry (SPIV) system was set up to map the flow of the air curtain, installed on top of the doorway, over a mannequin. …


Characterization Of Thermal Challenges In Electronics : Leakage Current, Co-Architectural Design And Rack Level Cooling, Uthaman Raju Jan 2008

Characterization Of Thermal Challenges In Electronics : Leakage Current, Co-Architectural Design And Rack Level Cooling, Uthaman Raju

Mechanical and Aerospace Engineering Theses - Archive

Since the advent of transistors and integrated circuits the complexity and functionality of the electronic products has gone up. In line with this, the scaling of the products is catching up at all levels of packaging. Current electronics era is driven by a mantra - "Miniaturization". Recently the number of transistors on high end microprocessor has exceeded a billon mark. The design at board level becomes sophisticated to meet the growing demands. All of these lead to thermal and reliability challenges. A good thermal design is one which makes sure that the chip is operating at its rated frequency or …


Novel Stabilization Methods For Sulfate And Non-Sulfate Soils, Chakkrit Sirivitmaitrie Jan 2008

Novel Stabilization Methods For Sulfate And Non-Sulfate Soils, Chakkrit Sirivitmaitrie

Civil Engineering Dissertations - Archive

Expansive soils are commonly found in arid and semi-arid climate zone. These soils typically exhibit moderate to high plasticity, low to moderate strength, and high swell and shrinkage characteristic which in turn result in more swelling problems when the soil absorbs water. Both low strength characteristic and volumetric movements weaken the subgrade soils that they may lead to structural distress on road pavements. This research project was conducted at the City of Arlington, Texas. Soils in Arlington are known to be highly expansive. The expansive soils consist of both sulfate-rich soils and non-sulfate soils. This research project was conducted to …


Mechanism Of Nanoparticle And Nanotube-Induced Cell Death, Syed Khaja Sohaebuddin Jan 2008

Mechanism Of Nanoparticle And Nanotube-Induced Cell Death, Syed Khaja Sohaebuddin

Bioengineering Theses - Archive

Recent advances in nanotechnology have lead to synthesis of high-quality nanoparticles which exhibit unique physical and chemical properties. The novel properties of these nanoparticles are widely being applied for diagnostic and therapeutic purposes and enable new means of biosensing and targeted drug delivery. However, increasing evidence has suggested that some nanoparticles may cause detrimental effects on cells and tissues. Using titanium oxide (TiO2) nanoparticles (5-10 nm diameter), silicon oxide (SiO2) nanoparticles (30 nm diameter), and multi-walled carbon nanotubes (MWCNTs) of different diameters (<8 nm, 20-30 nm, >50 nm), 0.5-2 µm in length as test subjects, we evaluated the in vitro interaction of these …


Integration Of Hyperspectral Imaging System For Optimized Data Acquisition And Control To Revolutionized Pathology Applications, Dipen Rana Jan 2008

Integration Of Hyperspectral Imaging System For Optimized Data Acquisition And Control To Revolutionized Pathology Applications, Dipen Rana

Bioengineering Theses - Archive

Detecting and measuring the interactions and expression levels of tumor markers in a cancerous cell are quintessential in prognosis and management of cancer. These have propagated the need to develop better microscopic imaging techniques to understand the cellular structure and its functional behavior. Pathologist use techniques such immunohistochemistry and in situ hybridization to measure and detect these tumor marker expression levels. Fluorophores are used in these techniques as fluorescent tags to identify the tumor markers. These fluorophores have unique absorption and emission spectrum, making them useful to not only identify but also quantify the concentration levels of these markers. This …


Synthesis And Characterization Of Crosslinked Urethane Doped Polyesters For Vascular Tissue Engineering, Jagannath Dey Jan 2008

Synthesis And Characterization Of Crosslinked Urethane Doped Polyesters For Vascular Tissue Engineering, Jagannath Dey

Bioengineering Theses - Archive

Traditional crosslinked polyester elastomers are inherently weak, and the strategy of increasing crosslink density to improve their mechanical properties makes them brittle materials. Biodegradable polyurethanes, although strong and elastic, do not fare well in dynamic environments due to the onset of permanent deformation. The design and development of a soft, strong and completely elastic (100% recovery from deformation) material for tissue engineering still remains a challenge. Herein, we report the synthesis and evaluation of a new class of biodegradable elastomers, crosslinked polyurethane-doped polyesters (CUPEs), which is able to satisfy the need for soft, strong, and elastic biomaterials. Tensile strength of …


Development Of Novel Multilayered Particles For Drug Delivery And Cell Isolation Applications, Bhanuprasanth Koppolu Jan 2008

Development Of Novel Multilayered Particles For Drug Delivery And Cell Isolation Applications, Bhanuprasanth Koppolu

Bioengineering Theses - Archive

The objective of this work is to develop multilayered nanoparticles for drug delivery and cell isolation applications. These particles principally consist of three layers; biodegradable polymer, thermo sensitive polymer and magnetic materials. For drug delivery, multilayered nanoparticles (MLNP) consisting of a magnetic core and two encompassing shells made up of temperature sensitive polymer, poly (N-isopropylacrylamide) (PNIPAAm), and biodegradable polymer, poly(D, L lactide-co-glycolide) (PLGA), were developed for targeted and controlled drug delivery. The PNIPAAm layer was immobilized onto magnetic nanoparticles (MNPs) via a silane coupling agent, Vinyltrimethoxysilane (VTMS), and free radical polymerization. These particles were then encapsulated with PLGA using a …


Unmanned Aerial Vehicle Routing With Limited Risk, Siriwat Visoldilokpun Jan 2008

Unmanned Aerial Vehicle Routing With Limited Risk, Siriwat Visoldilokpun

Industrial, Manufacturing, and Systems Engineering Dissertations - Archive

Due to safety and uninhabitable surrounding environments, long range Unmanned Aerial Vehicles (UAVs) have become an increasingly popular option in both scientific and military applications. With troubling oil prices, a logistic planner requires an efficient method to identify an optimal routing solution. The solution should not only optimize the bottom line objective but must also control variations in an operation.We study the UAV routing problem with limited risk (URPR) in which the considered risk is a fuel burn variance caused by wind variation. The URPR determines the optimal route that minimizes total expected fuel burn to visit all assigned targets …


Synthesis, Structure And Characterization Of Silver Doped Diamond Like Carbon Thin Films, Pankaj Jyoti Hazarika Dec 2007

Synthesis, Structure And Characterization Of Silver Doped Diamond Like Carbon Thin Films, Pankaj Jyoti Hazarika

Material Science and Engineering Theses - Archive

Diamond like carbon (DLC) films have gained grounds in the biomedical field as an inert, biocompatible, low friction and wear resistant coating and are widely used in heart valves, coronary artery stents, dental implants, knee prosthesis and other vascular devices. In addition, Ag nanoparticles/films can prevent the formation of biofilm on biomedical implants by degrading the metabolic activities like permeability and respiration and also impair DNA replicability. Thus, Ag-doped DLC (Ag-DLC) can serve as a multifunctional bio coating combining desirable antibacterial and physical/ mechanical characteristics. In the present study, Ag-DLC films were synthesized utilizing a hybrid Plasma CVD and Magnetron …


Synthesis And Characterization Of Ferromagnetic Nanoparticles, Kazuaki Yano Dec 2007

Synthesis And Characterization Of Ferromagnetic Nanoparticles, Kazuaki Yano

Material Science and Engineering Theses - Archive

Ferromagnetic nanoparticles and their bimagnetic nanoparticles with uniform size distribution have drawn great attention in the past decades because of their unique magnetic properties and potential applications in high density recording media, exchange-spring permanent magnets and biotechnology. In this thesis, synthesis and characterization of ferromagnetic nanoparticles (FePt, Sm-Co system) and bimagnetic nanoparticles (FePt/Fe3O4, FePt/Au) are reported. FePt nanoparticles with different sizes and compositions were successfully synthesized via chemical synthesis. FePt particle size was tuned to a range of from 3 nm to 8 nm with 1 nm accuracy by changing the surfactant to Pt precursor ratio. By optimizing the amount …


On The Near Field Mean Flow Structure Of Transverse Jets Issuing Into A Supersonic Freestream, Dean Anthony Dickmann Dec 2007

On The Near Field Mean Flow Structure Of Transverse Jets Issuing Into A Supersonic Freestream, Dean Anthony Dickmann

Mechanical and Aerospace Engineering Dissertations - Archive

The near field mean flow structure of transverse jets issuing from a surface into supersonic crossflow is examined using numerical methods and separation topology. The Navier-Stokes solver Falcon, developed at Lockheed Martin, was used to simulate the interaction between the jet and freestream over a flat plate and a generic missile body. The near field flow structure included a l bow shock upstream of the jet interacting with the approaching boundary layer that forms a pair of horseshoe vortices while another l- structure closer to the jet formed a second pair of horseshoe vortices. As the jet was turned downstream …


Methodologies For Automated Microassembly, Mohammad A. Mayyas Dec 2007

Methodologies For Automated Microassembly, Mohammad A. Mayyas

Mechanical and Aerospace Engineering Dissertations - Archive

The development of micromachining technologies has provided wide applications in micro sensing and actuation. However, most of the demonstrated devices are selectively constructed by fabrication processes that are limited to complexity, configuration, dimension, and material variation. The monolithic fabrication has limitations and does not allow the inclusion of multiple components of incompatible processes. Therefore, the construction of 3D microstructures by heterogeneous microassembly is an alternate manufacturing route. In deterministic, monitored or controlled microassembly there has been considerable research in developing, analyzing and applying distributed algorithms for sensor and sensorless based assembly processes. Meso-scale teleoperated work-cells supported by Nano manipulators have …


Thermal Enhancement Of Stacked Dice Replacing Wire Bonds With Through Silicon Vias At Location Of Die Pads, Venkata Chepuri Krishna Teja Dec 2007

Thermal Enhancement Of Stacked Dice Replacing Wire Bonds With Through Silicon Vias At Location Of Die Pads, Venkata Chepuri Krishna Teja

Mechanical and Aerospace Engineering Theses - Archive

Through Silicon vias can offer quick time to market of circuits designed in a modular manner and can also be used to customize the product according to the needs of the customers. This gives a way to avoid both excess inventory risks and larger footprints. A through silicon via could be described as, a vertical component through which a backside interconnect for a pair of bonded wafers forming a wafer stack is ultimately cut into a number of stacked dice. Various embodiments have been patented [1, 2] but implementation of these architectures can be inhibited based on thermal, mechanical and …


Numerical Simulation Of Magnetohydrodynamics, Takahiro Sonoda Dec 2007

Numerical Simulation Of Magnetohydrodynamics, Takahiro Sonoda

Mechanical and Aerospace Engineering Theses - Archive

Use of electromagnetic fields has been shown to be an effective way to control the behavior of electrically conducting fluids. Specifically, the modification of the boundary layer profile with electromagnetic fields can yield performance improvements such as reduced drag and improved heat transfer. Though this approach has been demonstrated computationally and experimentally with conducting liquids (i.e. seawater), application to aerodynamic devices operating in air has not seen the same success. Through the use of numerical simulation and eventually optimization, we hope to develop efficient designs that are effective for boundary layer control for low temperature conducting gases (non-thermal plasmas). The …


An Experimental Study On Thermal Bonding Effects Of Pmma Based Micro-Devices Using Hot Embossing, Varun Sood Dec 2007

An Experimental Study On Thermal Bonding Effects Of Pmma Based Micro-Devices Using Hot Embossing, Varun Sood

Mechanical and Aerospace Engineering Theses - Archive

Basic configuration and functioning of various subsystems of a developed HEMM system for thermal bonding are discussed. The bond strength and micro channel geometry degradations dependence on controlled process parameters in thermal bonding using hot embossing has been investigated. The process parameters examined were bonding temperature, bonding or applied load and holding time. Polymeric substrates with different feature dimensions and thickness were embossed and bonded using hot embossing technology. The feature dimensions before and after bonding were examined to assess the geometry changes as functions of the bonding process. This assessment could provide guidance during the design phase of micro-fluidic …


Derivation Of The Dynamics Equations For Receiver Aircraft In Aerial Refueling, Jayme Lynn Waishek Dec 2007

Derivation Of The Dynamics Equations For Receiver Aircraft In Aerial Refueling, Jayme Lynn Waishek

Mechanical and Aerospace Engineering Theses - Archive

This thesis describes the derivation of a new set of nonlinear, 6--DOF equations of motion of a receiver aircraft undergoing an aerial refueling, including the effect of time-varying mass and inertia properties associated with the fuel transfer and the tanker's vortex induced wind effect. Since the center of mass of the receiver is time--varying during the fuel transfer, the equations are written in a reference frame that is geometrically fixed in the aircraft. Due to the fact that aerial refueling simulation and control deal with the position and orientation of the receiver relative to the tanker, the equations of motion …


Trends Of Vehicular Emissions For Clean Air Associates Precombustion Retrofit Device, Jaya Vani Nagireddi Dec 2007

Trends Of Vehicular Emissions For Clean Air Associates Precombustion Retrofit Device, Jaya Vani Nagireddi

Civil Engineering Theses - Archive

The research study objective was to find if there was any reduction in onboard exhaust emissions from a light duty passenger car (2007 Dodge Charger) with a Clean Air Catalytic Converter manufactured by Clean Air Associates, Inc. The research was conducted by the Civil and Environmental Engineering Department, University of Texas at Arlington as part of the North Central Texas Council of Governments Aftermarket Technology and Fuel Additive Research Program. Initially, emissions of pollutants were measured without the Clean Air Associates' retrofit device, called Baseline testing. A Horiba OBS-1300 On-Board System measured concentrations of the pollutants NOx, CO, CO2 and …


Modeling Unsaturated Soil Response Under Suction-Controlled Multi-Axial Stress States, Arthit Laikram Dec 2007

Modeling Unsaturated Soil Response Under Suction-Controlled Multi-Axial Stress States, Arthit Laikram

Civil Engineering Dissertations - Archive

In this research work, a novel suction-controlled true triaxial testing apparatus has been developed to test 3-in (7.5-cm) side, cubical specimens of unsaturated soil under controlled-suction states for a wide range of stress paths that are not easily achievable in a conventional cylindrical apparatus. The equipment is a mixed-boundary type of device, with the specimen seated on top of a high-air-entry ceramic disk and between five flexible (latex) membranes on the remaining sides of the cube. The new cell is an upgraded, more elaborate version of the one previously reported by Hoyos (1998), featuring two independent pore-air and pore-water pressure …


Suppressing Delta-I Noise In Mcml Circuits In Mixed Signal Environment, Ritesh Jayant Mehta Dec 2007

Suppressing Delta-I Noise In Mcml Circuits In Mixed Signal Environment, Ritesh Jayant Mehta

Electrical Engineering Theses - Archive

This work addresses the problem of simultaneous switching noise (SSN) in mixed signal environment. It is shown that the Metal Oxide Semiconductor Current Mode Logic (MCML) can be used to minimize the SSN. In short channel devices, Drain Induced Barrier Lowering (DIBL) effect causes the current mismatch problem. It is seen that this current mismatch problem aggravates SSN. Basic logic gates were designed using MCML topology at 5 Gbps. Parasitic model was introduced at power supply lines and substrate to study the behaviour of these logic gates in the presence of parasitics. Interpolation type delay cells were used to suppress …


Stress Distribution And Strength Prediction Of Composite Laminates With Multiple Holes, Brian Esp Dec 2007

Stress Distribution And Strength Prediction Of Composite Laminates With Multiple Holes, Brian Esp

Mechanical and Aerospace Engineering Dissertations - Archive

The major purpose of this study was to investigate failure of composite laminates with multiple unloaded holes in close proximity. The least square boundary collocation method for anisotropic materials was utilized to determine the state of stress. The approach utilized collocation on both the internal and external boundaries, making it relatively easy to implement. The method compared favorably to both published and finite element solutions. A failure prediction approach for an infinite, symmetric and balanced laminate, with two holes in close proximity was presented. The baseline material for consideration was IM7/977-3, a carbon fiber/epoxy lamina. The failure prediction method was …