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Articles 1981 - 2010 of 2584

Full-Text Articles in Engineering

Evaluation Of Utility Relocation Costs And Best Management Practices, Michael Reinke Dec 2010

Evaluation Of Utility Relocation Costs And Best Management Practices, Michael Reinke

All Theses

In recent years, the SCDOT has experienced a significant variation in estimated costs for the relocation of utilities on many projects. This has led to cost overruns and caused concerns for the district engineers responsible for the projects. Through meetings with SCDOT personnel and utility company representatives it was determined that a standardized cost estimate form combined with improved change order management and cost management strategies was needed. Recently submitted estimates were analyzed and rated by a panel on multiple criteria to generate a list of 'poor', 'good', and 'excellent' estimates. The 'excellent' estimates provided insight into the development of …

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Mass And Assembly Time Reduction For Future Generation Automotive Vehicles Based On Existing Vehicle Model, Essam Namouz Dec 2010

Mass And Assembly Time Reduction For Future Generation Automotive Vehicles Based On Existing Vehicle Model, Essam Namouz

All Theses

This research presents method for evaluating the lightweightedness of a vehicle and an approach for vehicle assembly time savings potential developed through a case study. The Lazy Part Identification method for mass reduction specifically addresses those components whose primary purpose is to aid in manufacturing and assembly rather than to provide end-user function. Seven specific laziness indicators are described and illustrated: rigid-to-rigid connection, support for a flexible, non-moving part, positioning feature, duplicate geometry, fastener, bridging system, and material flow restriction. These indicators are used to evaluate individual vehicle components as part of a proposed method for identifying mass reduction potential. …

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Analysis Of Alternative Manufacturing Processes For Lightweight Biw Designs, Using Analytical Hierarchy Process, Srinath Vijayakumar Dec 2010

Analysis Of Alternative Manufacturing Processes For Lightweight Biw Designs, Using Analytical Hierarchy Process, Srinath Vijayakumar

All Theses

The main objective of the analysis was to investigate the forming of Body in White (BIW) panels using alternative processes most suitable for replacing the conventional press working process in order to achieve a reduction in the total mass of the vehicle body structure. The selection of the alternatives was guided by multi criteria decision making tool, the Analytic Hierarchy Process (AHP). Here the alternatives were selected based on their relative importance to the different manufacturing attributes considered. The selected processes were applied to the manufacturing of different parts of BIW indicated in the BOM along with suggestion of the …

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Circuit Modules For Cmos High-Power Short Pulse Generators, Yongtao Geng Dec 2010

Circuit Modules For Cmos High-Power Short Pulse Generators, Yongtao Geng

All Theses

High-power short electrical pulses are important for high-performance functionality integration, such as the development of microelectromechanical/nanoelectromechanical systems (MEMS/NEMS), system on chip (SoC) and lab on chip (LoC). Many of these applications need high-power (low impedance load) short electrical pulses, in addition to CMOS digital intelligence. Therefore, it is of great interest to develop new circuit techniques to generate high-power high-voltage short electrical pulses on-chip.
Results on pulse forming line (PFL) based CMOS pulse generator studies are reported. Through simulations, the effects of PFL length, switch speed and switch resistance on the output pulses are clarified. CMOS pulse generators are modeled …

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Determining The Global Maximum Biofuel Production Potential Without Conflicting With Food And Feed Consumption, Watcharapol Pumkaew Dec 2010

Determining The Global Maximum Biofuel Production Potential Without Conflicting With Food And Feed Consumption, Watcharapol Pumkaew

All Theses

This study tries to resolve the competition between food and biofuel by balancing the allocation between food and feed areas and biofuel areas for the entire world. The maximum energy production is calculated by determining the theoretical amount of energy that can be grown, once food and feed consumption is taken into account, based on the assumption that unprotected grass and woody lands and forest lands can be converted into cultivated lands. The total optimum land area for biofuel energy, 4,926.49 Mha, consists of corn, rapeseed, sugar beet, sugar cane, and grasses. When considering energy conversion efficiency, the maximum energy …

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Molecular Physics Of Electrical Double Layers In Electrochemical Capacitors, Guang Feng Dec 2010

Molecular Physics Of Electrical Double Layers In Electrochemical Capacitors, Guang Feng

All Dissertations

At present, electrochemical capacitors (ECs) are emerging as a novel type of energy storage devices and have attracted remarkable attention, due to their key characteristics, such as high power density and excellent durability. However, the moderate energy density of ECs restricts their widespread deployment in everyday technology. To surmount this limitation, four strategies are adopted: (1) to reduce the total system mass, (2) to increase the specific surface area of electrodes, (3) to enhance normalized capacitance, and (4) to expand the range of potentials applied on electrodes. The implementation of these approaches critically relies on the fundamental understanding of physical …

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An Investigation Of Metaheuristics Using Path- Relinking On The Quadratic Assignment Problem, Thashika Rupasinghe Dec 2010

An Investigation Of Metaheuristics Using Path- Relinking On The Quadratic Assignment Problem, Thashika Rupasinghe

All Dissertations

The Quadratic Assignment Problem (QAP) is a widely researched, yet complex, combinatorial optimization problem that is applicable in modeling many real-world problems. Specifically, many optimization problems are formulated as QAPs. To resolve QAPs, the recent trends have been to use metaheuristics rather than exact or heuristic methods, and many researchers have found that the use of hybrid metaheuristics is actually more effective. A newly proposed hybrid metaheuristic is path relinking (PR), which is used to generate solutions by combining two or more reference solutions. In this dissertation, we investigated these diversification and intensification mechanisms using QAP. To satisfy the extensive …

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Circuit Modules For Broadband Cmos Six-Port Systems, Chaojiang Li Dec 2010

Circuit Modules For Broadband Cmos Six-Port Systems, Chaojiang Li

All Dissertations

This dissertation investigates four circuit modules used in a CMOS integrated six-port measurement system. The first circuit module is a wideband power source generator, which can be implemented with a voltage controlled ring oscillator. The second circuit module is a low-power 0.5 GHz - 20.5 GHz power detector with an embedded amplifier and a wideband quasi T-coil matching network. The third circuit module is a six-port circuit, which can be implemented with distributed or lumped- lement techniques. The fourth circuit module is the phase sifter used as calibration loads. The theoretical analysis, circuit design, simulated or experimental verifications of each …

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Comprehensive Thermal Modeling Of Power Split Hybrid Power-Train And Electronics, Abdel Mayyas Dec 2010

Comprehensive Thermal Modeling Of Power Split Hybrid Power-Train And Electronics, Abdel Mayyas

All Dissertations

Hybrid electric vehicle (HEV) uses both internal combustion engine (ICE) with an electric system. The combination of the electric power train with the ICE is intended to achieve both better fuel economies than the conventional vehicles and better performance. Several types of HEV exist with different layouts. Recent HEVs' make use of regenerative braking, which converts the vehicles' kinetic energy into electric energy instead of wasting it as heat as conventional brakes do. A hybrid-electric is more fuel efficient than ICE and has less environmental impact.
The new HEV with its new Key Characteristics and Configurations (i.e. Mechanical complexity, Multiple …

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Packet Error Rate Predictive Model For Sensor Radios On Fast Rotating Structures, Lei Tang Dec 2010

Packet Error Rate Predictive Model For Sensor Radios On Fast Rotating Structures, Lei Tang

All Dissertations

Wireless sensing technologies have raised widespread interests in the applications for monitoring fast rotating or moving machinery structures in manufacturing environments. Over the past five years, a few wireless sensor systems have been implemented and proven to feasibly work under fast rotation conditions. However, few of these studies evaluated data transmission performance of the wireless communication systems. Although the manufacturing environments are known to be harsh for wireless communication, in many cases, an excellent data throughput is critical for such systems. Conventional statistical methods for studying wireless communication channels are not sufficient in this specific field.
This dissertation presents systematic …

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High Frequency Ferromagnetic Inductive Elements For On-Chip Integration And Their Magnetization Dynamics, Hanqiao Zhang Dec 2010

High Frequency Ferromagnetic Inductive Elements For On-Chip Integration And Their Magnetization Dynamics, Hanqiao Zhang

All Dissertations

The dissertation focuses on the broadband characterization of magnetization dynamics of submicron (200-550 nm wide, 10 µm long, 100 nm thick) and micron (2-10 µm wide, 100 µm long, 100 nm thick) size patterned ferromagnetic material (Permalloy, Py) with low frequency and microwave measurement methods. Particularly the ferromagnetic resonance (FMR), damping process, magnetization reversal, mag-noise, and 1/f noise in different pattern geometry, DC current and external magnetic field bias situations are investigated. In addition to simple microwave transmission line measurements, a sensitive on-chip microwave interferometer is proposed and fabricated by means of nano-fabrication techniques. The FMR properties of an individual …

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Pulsed-Laser Direct Writing Of Biological Materials, Yafu Lin Dec 2010

Pulsed-Laser Direct Writing Of Biological Materials, Yafu Lin

All Dissertations

Laser direct writing, developed based on modified laser-induced forward transfer (LIFT), has been emerging as one of the most promising biofabrication techniques. While some studies have been conducted to investigate laser direct writing of biological materials, there are some key challenges such as mechanisms of bubble formation, droplet formation and process-induced cell injury that have not been well elucidated. The objective of this dissertation is to study laser-induced droplet formation dynamics and process-induced cell injury in pulsed-laser direct writing of biological materials, and improve the existing laser direct-write techniques.
Phase explosion is identified as the dominant bubble formation mechanism in …

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Modulated Properties Of Fully Absorbable Bicomponent Meshes, Shawn Peniston Dec 2010

Modulated Properties Of Fully Absorbable Bicomponent Meshes, Shawn Peniston

All Dissertations

Current meshes used for soft-tissue repair are mostly composed of single component, nonabsorbable yarn constructions, limiting the ability to modulate their properties. This situation has left the majority of soft tissue repair load-bearing applications to suffer distinctly from undesirable features associated, in part, with mesh inability to (1) possess short-term stiffness to facilitate tissue stability during the development of wound strength; (2) gradually transfer the perceived mechanical load as the wound builds mechanical integrity; and (3) provide compliance with load transfer to the remodeling and maturing mesh/tissue complex. The likelihood of long-term complications is reduced for fully absorbable systems with …

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Predictive Energy Management In Connected Vehicles: Utilizing Route Information Preview For Energy Saving, Chen Zhang Dec 2010

Predictive Energy Management In Connected Vehicles: Utilizing Route Information Preview For Energy Saving, Chen Zhang

All Dissertations

This dissertation formulates algorithms that use preview information of road terrain and traffic flow for reducing energy use and emissions of modern vehicles with conventional or hybrid powertrains. Energy crisis, long term energy deficit, and more restrictive environmental protection policies require developing more efficient and cleaner vehicle powertrain systems. An alternative to making advanced technology engines or electrifying the vehicle powertrain is utilizing ambient terrain and traffic information in the energy management of vehicles, a topic which has not been emphasized in the past. Today's advances in vehicular telematics and advances in GIS (Geographic Information System), GPS (Global Positioning Systems), …

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Order Picking And Storage Using Stackable Pallets In A Warehouse, Ahmed Hassan Aly Dec 2010

Order Picking And Storage Using Stackable Pallets In A Warehouse, Ahmed Hassan Aly

All Dissertations

Quarter Billion dollars could be saved annually by double stacking pallets. A forklift storing 100 double stacked pallets saves 2.5 working hours versus single pallets. More than one billion pallets and cases handled between Wal-Mart distribution centers according to BEA White Paper (2006) [1], assume only 500 million were stackable pallets. This translates to 12.5 million working hours. If a forklift driver earns $20 per hour, then $250 million can be saved.
Moreover, handling double stacked pallets takes up to 46 % of total time to pick and store. This is a significant element that was ignored in literature. All …

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Utilizing Copper(I) Catalyzed Azide-Alkyne Huisgen 1,3-Dipolar Cycloaddition For The Surface Modification Of Colloidal Particles With Electroactive And Emissive Moieties, Parul Rungta Dec 2010

Utilizing Copper(I) Catalyzed Azide-Alkyne Huisgen 1,3-Dipolar Cycloaddition For The Surface Modification Of Colloidal Particles With Electroactive And Emissive Moieties, Parul Rungta

All Dissertations

The development of charge–transporting and fluorescing colloidal particles that can be directly printed into electroluminescent devices may result in a broad impact on the use of electrical energy for illumination. The objective of this work was to design and synthesize electroactive & fluorescing colloidal particles; establish their optical, electronic, and thermodynamic properties; and transition them into a device format for potential applications. The original intended application of this work was to build “better” colloidally–based organic light emitting devices (OLEDs) by creating functional particles with superior electrical and optical performance relative to commercially available technologies, but through the course of the …

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Modeling Microbial And Nutrient Dynamics In Zero-Discharge Aquaculture Systems, Kendall Kirk Dec 2010

Modeling Microbial And Nutrient Dynamics In Zero-Discharge Aquaculture Systems, Kendall Kirk

All Dissertations

A finite element, finite difference model was developed to predict nutrient and microbial dynamics in recirculating aquaculture systems. Total ammonia nitrogen, nitrite, nitrate, chemical oxygen demand, and dissolved oxygen concentrations are predicted in addition to growth and decay of algae, Nitrosomonas, Nitrobacter, denitrifying heterotrophs, and aerobic heterotrophs. Inputs to the model include temperature, photosynthetically available radiation, feed application rate, pH, aeration/mixing energy, water exchange configuration, water exchange rate, tilapia biomass, and dissolved oxygen concentration. Up to 10 exchanged units may be included, user-definable as continuous stirred tank reactors or sequencing batch reactors. Demonstration of the model's utility was demonstrated through …

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Assortment Planning For Multiple Quality Levels Using Locational Choice, Mark Mcelreath Dec 2010

Assortment Planning For Multiple Quality Levels Using Locational Choice, Mark Mcelreath

All Dissertations

Assortment planning is the process in which a retailer selects a product line to offer to customers and is a key determinant of a retailer's profit. We consider the assortment planning problem using a locational choice model for customer product selection and allow for both horizontal and vertical product differentiation. When the distribution of customer preference is unimodal, the optimal solutions for this problem are unknown. We propose two solution philosophies for generating product assortments. First, we introduce a metaheuristic representation for the problem and test the performance of three metaheuristic techniques. We suggest that a tabu search or genetic …

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Novel Vascular Grafts Based On Polyphenol-Stabilized Acellular Tissue Scaffolds, Ting-Hsien Chuang Dec 2010

Novel Vascular Grafts Based On Polyphenol-Stabilized Acellular Tissue Scaffolds, Ting-Hsien Chuang

All Dissertations

The Cardiovascular diseases (CVDs) continue to be the leading cause of morbidity and mortality worldwide. The most common form of CVDs is occlusion of blood flow thus limiting blood supply to specific tissues or organs. Atherosclerosis is a leading cause of coronary heart disease and stroke, which were responsible for more than 25% of deaths in 2004.
The demand for vascular graft is huge. In United States alone, approximately 500,000 coronary artery bypass graft surgeries are performed annually. Synthetic polymers such as Dacron and ePTFE have been successfully applied in large diameter blood vessel prosthesis; however, for small diameter (inner …

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Effect Of Impurities On Performance Of Proton Exchange Membrane Fuel Cell Components, Kitiya Hongsirikarn Dec 2010

Effect Of Impurities On Performance Of Proton Exchange Membrane Fuel Cell Components, Kitiya Hongsirikarn

All Dissertations

It is believed that proton–exchange membrane fuel cells (PEMFCs) are going to be exploited as power generation devices for stationary, automotive, and portable applications in the near future because of their high performance and environmental friendliness. Up to the present, wide spread utilization of PEMFCs is not viable because of their cost and durability in the presence of fuel and oxidant stream impurities. These impurities include NH3, hydrocarbons, CO, CO2, halogenated compounds, cations, etc. The objective of this research was to investigate the effect of these harmful contaminants containing in the H2 fuel stream on …

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A Study Of The Statistics Of The Air/Water Interfacial Temperature Field During Mixed Convection Heat Transfer, Jie Kou Dec 2010

A Study Of The Statistics Of The Air/Water Interfacial Temperature Field During Mixed Convection Heat Transfer, Jie Kou

All Dissertations

Heat transfer across an air/water interface is of particular importance to limnology, oceanography and some industrial applications. The relationship between the statistics of the air/water interfacial temperature field and the interfacial heat flux is poorly understood, particularly for the mixed convection condition, which is a common heat transfer mechanism for small inland lakes. The few studies that have been conducted under mixed convection conditions have been limited to an uncontrolled surfactant condition (tap water). Therefore, in this dissertation research two sets of experiments for wind speeds from 0 to 4 m/s were conducted: controlled surfactant contaminated conditions (with oleyl alcohol) …

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Evaluation Of Factors That Modulate Cellular Adipogenesis For Breast Tissue Engineering Strategies, Cheryl Gomillion Dec 2010

Evaluation Of Factors That Modulate Cellular Adipogenesis For Breast Tissue Engineering Strategies, Cheryl Gomillion

All Dissertations

It is estimated that this year more than 200,000 women in the United States will be diagnosed with breast cancer. Treatment for most occurrences of breast cancer will often include surgical removal of the tumorigenic tissue, resulting in a soft tissue defect within the subcutaneous tissue of the skin. Post-surgical reconstruction methods are often sought by patients to restore the aesthetic function of the breast via cellular or non-cellular methods; however, because of complications associated with currently used methods for breast reconstruction, researchers are investigating tissue engineering methods to produce viable autologous adipose tissue for breast reconstruction.
Previous research in …

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Production And Characterization Of Aramid Copolymer Fibers For Use In Cut Protection, Jeffrey Moreland Dec 2010

Production And Characterization Of Aramid Copolymer Fibers For Use In Cut Protection, Jeffrey Moreland

All Dissertations

High-performance fibers such as para-aramids are used extensively in gloves for cut protection. However, the inherent cut resistance of these fibers and the relationship between cut resistance and other material properties is not known. To better understand cut resistance at the material level, an experiment was conducted using a lab-scale wet spinning system to produce and characterize aramid copolymer fibers.
To facilitate the use of lab-scale equipment, the experiment was conducted as a four-factor split-plot response surface design. The four treatment factors studied were solvent concentration in the coagulation bath, the amount of salt in the coagulation bath, the degree …

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Studies Relevant To The Design Of Reliable Automotive Electronics, Hua Zeng Dec 2010

Studies Relevant To The Design Of Reliable Automotive Electronics, Hua Zeng

All Dissertations

This dissertation describes three independent studies related to the design of reliable automotive electronics. The topics covered are: the estimation of the radiated emissions from power bus structures, EM propagation of tire pressure monitoring systems (TPMS), and examinations of corrosion-induced faults in a connector.
The first chapter describes a method for estimating the maximum possible radiated emissions from a printed circuit board power bus. An analysis based on a lossy cavity model is performed to determine the maximum possible radiated field corresponding to a given power bus noise voltage. A closed-form expression relating the maximum power bus noise voltage to …

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Development Of A Physical Windkessel Module To Re-Create In Vivo Vascular Flow Impedance For In Vitro Experiments, Ethan Kung, Charles A. Taylor Nov 2010

Development Of A Physical Windkessel Module To Re-Create In Vivo Vascular Flow Impedance For In Vitro Experiments, Ethan Kung, Charles A. Taylor

Publications

To create and characterize a physical Windkessel module that can provide realistic and predictable vascular impedances for in vitro flow experiments used for computational fluid dynamics validation, and other investigations of the cardiovascular system and medical devices. We developed practical design and manufacturing methods for constructing flow resistance and capacitance units. Using these units we assembled a Windkessel impedance module and defined its corresponding analytical model incorporating an inductance to account for fluid momentum. We tested various resistance units and Windkessel modules using a flow system, and compared experimental measurements to analytical predictions of pressure, flow, and impedance. The resistance …

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Non-Contact Spatially Constrained Optical Scanning Methods Applied For Depth, Width And Gap Measurements, Konda Reddy Thotti Reddy Aug 2010

Non-Contact Spatially Constrained Optical Scanning Methods Applied For Depth, Width And Gap Measurements, Konda Reddy Thotti Reddy

All Theses

The thesis presents the non-contact laser projection based systems utilized for quantifying the feature dimensions like width, depth and air gaps. Laser diode, Charge coupled device (CCD) and post-processing software using image processing tools are the major components of the non-contact measurement systems. The study involves two methods where the first method comprises of active laser-based triangulation and morphological edge detection for depth and width measurement applications. The second method uses edge detection technique and Dynamic Field of View (DFOV) for gap detection and tracking. Using the developed techniques, the case studies are conducted with smooth plastic fenders with induced …

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Combined Musculo-Skeletal Multi-Body Dynamics/Finite Element Analysis Of Several Ergonomics And Bio-Mechanics Problems, Xin Xie Aug 2010

Combined Musculo-Skeletal Multi-Body Dynamics/Finite Element Analysis Of Several Ergonomics And Bio-Mechanics Problems, Xin Xie

All Theses

Within this thesis, two ergonomics (i.e. seating comfort and long-distance driving fatigue problems) and two structural bio-mechanics (i.e. femur-fracture fixation and radius-fracture fixation) problems are investigated using musculo-skeletal multi-body dynamics and finite element computational analyses.
Within the seating comfort problem analyzed, a complete-body finite element model is constructed and used to assess the effect of seat geometry and seating posture on the feel of comfort experienced by a seated human.
Within the long-distance driving fatigue problem, musculo-skeletal analysis is employed to assess the extent of fatigue experienced by a driver through the evaluation of level of activity of his/her various …

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Selection Of Channel-Access And Routing Protocols For Mobile Ad Hoc Networks With Frequency-Agile Radios And Directional Antennas, Rebekah Schloemann Aug 2010

Selection Of Channel-Access And Routing Protocols For Mobile Ad Hoc Networks With Frequency-Agile Radios And Directional Antennas, Rebekah Schloemann

All Theses

In this thesis, ad hoc networks with frequency-agile radios utilizing omni-directional and directional antennas form the basis of study. This work focuses on the selection of channel-access and routing protocols for these networks. Findings demonstrate that protocol selection must occur jointly in order to increase the efficient utilization of available spectrum while achieving maximum network performance.
In this thesis, we investigate several channel-access methods that provide different ways of selecting one of the heterogeneous non-overlapping channels for transmission. We also investigate a modification of least-resistance routing that accounts for the variations in transmission channels. Through simulation, we find that better …

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Microstructure Modification Of Cu0.2ag2.8sbsete2 Through, Sloan Lindsey Aug 2010

Microstructure Modification Of Cu0.2ag2.8sbsete2 Through, Sloan Lindsey

All Theses

Cu0.2Ag2.8SbSeTe2 is new potential thermoelectric compound that exhibits very low thermal conductivity and a region of glass-like thermal conductivity. The compound phase segregates into AgSbTe2 and Ag2Te phases with Se and Cu acting as isoelectronic dopants. Backscatter SEM imaging is used to study the resulting microstructure. Normally cast samples exhibit cracks forming near the interfaces of the two phases. In this work we show that the cracks are caused by a low temperature monoclinic to cubic phase transition that occurs in the Ag2Te phase. We demonstrate that through rapid quenching we can control the size and shape of the phase …

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Structural Bioinformatics Based Method For Predicting The Initial Adsorbed Protein Orientation On A Surface, Aby Thyparambil Aug 2010

Structural Bioinformatics Based Method For Predicting The Initial Adsorbed Protein Orientation On A Surface, Aby Thyparambil

All Theses

In any molecular simulation of protein-surface interaction, the selection of the initial orientation with which the protein would interact with the surface must be first made and is found to be critical in the determination of the bioactive state of the adsorbed protein. While various molecular simulation methods have been developed to identify the preferred orientation, these methods are generally computationally expensive and time consuming, especially for large molecules thereby motivating the current study.
The computational implementation for identifying a preferred orientation was done in MATLAB¨ and directly addresses the current research problem by assuming the protein to be rigid …

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