Open Access. Powered by Scholars. Published by Universities.®

Engineering Commons™

Open Access. Powered by Scholars. Published by Universities.®

Theses and Dissertations

Discipline
Institution
Keyword
Publication Year

Articles 7711 - 7740 of 11510

Full-Text Articles in Engineering

Automated Methods For Fiber Diameter Measurement Of Fibrous Scaffolds, Anna Bulysheva Dec 2009

Automated Methods For Fiber Diameter Measurement Of Fibrous Scaffolds, Anna Bulysheva

Theses and Dissertations

The purpose of this work was to develop an automated method of measuring fiber diameters of electrospun scaffolds from scanning electron microscopy images of these scaffolds. Several automated methods were developed and evaluated by comparison to known values and data obtained via the standard manual method. Simulated images with known diameters were used as test images to evaluate the accuracy of each measurement technique. Eight scanning electron microscopy images were also used for the evaluation of the automated methods compared to the standard manual method. All diameter measurements were made in pixels. Five new automated methods coded in MATLAB were …

Go to article

Efficient Implementation Of Raid-6 Encoding And Decoding On A Field Programmable Gate Array (Fpga), David Jacob Dec 2009

Efficient Implementation Of Raid-6 Encoding And Decoding On A Field Programmable Gate Array (Fpga), David Jacob

Theses and Dissertations

RAID-6 is a data encoding scheme used to provide single drive error detection and dual drive error correction for data redundancy on an array of disks. Here we present a thorough study of efficient implementations of RAID-6 on field programmable gate arrays (FPGAs). Since RAID-6 relies heavily on Galois Field Algebra (GFA), an efficient implementation of a GFA FPGA library is also presented. Through rigorous performance analysis, this work shows the most efficient ways to tradeoff FPGA resources and execution time when implementing GFA functions as well as RAID-6 encoding and decoding.

Go to article

Experimental And Numerical Investigation On Pyroelectric Energy Scavenging, Jingsi Xie Dec 2009

Experimental And Numerical Investigation On Pyroelectric Energy Scavenging, Jingsi Xie

Theses and Dissertations

Pyroelectric energy scavenging is the process of converting wasted energy from a system to power another one, based on the pyroelectric effect of piezoelectric materials. Pyroelectrically generated power is a function of the surface of material, the pyroelectric coefficient, and the temporal temperature gradient. In the current project, a simple model is developed to predict the power generation based on the temporal change in temperature of material. In addition, a model is validated with experimental measurements from several piezoelectric materials. It is shown that energy generation can be enhanced by using piezoelectric materials with significantly higher pyroelectric coefficients such as …

Go to article

Prediction Of Fluid Viscosity Through Transient Molecular Dynamic Simulations, Jason Christopher Thomas Dec 2009

Prediction Of Fluid Viscosity Through Transient Molecular Dynamic Simulations, Jason Christopher Thomas

Theses and Dissertations

A novel method of calculating viscosity from molecular dynamics simulations is developed, benchmarked, and tested. The technique is a transient method which has the potential to reduce CPU requirements for many conditions. An initial sinusoidal velocity profile is overlaid upon the peculiar velocities of the individual molecules in an equilibrated simulation. The transient relaxation of this initial velocity profile is then compared to the corresponding analytical solution of the momentum equation by adjusting the viscosity-related parameters in the constitutive equation that relate the shear rate to the stress tensor. The newly developed Transient Molecular Dynamics (TMD) method was tested for …

Go to article

The Effect Of Flowable Fill On The Lateral Resistance Of Driven-Pile Foundations, Dustin David Miner Dec 2009

The Effect Of Flowable Fill On The Lateral Resistance Of Driven-Pile Foundations, Dustin David Miner

Theses and Dissertations

Flowable fill was used to strengthen the soft soil surrounding piles and behind the pile cap. The flowable fill placed beneath the pile cap surrounding the piles showed no appreciable increase in lateral resistance, this was partially due to the fact that the flowable fill placed had an unconfined compressive strength of 30 psi. Flowable fill was also used to replace a 12 ft wide, 6 ft thick, and 6 ft deep zone consisting of an average 475 psf clay that was adjacent to a 9-pile group in 3x3 pile configuration capped with a 9 ft x 9 ft x …

Go to article

Studies Of Coal Nitrogen Release Chemistry For Oxyfuel Combustion And Chemical Additives, John M. Sowa Nov 2009

Studies Of Coal Nitrogen Release Chemistry For Oxyfuel Combustion And Chemical Additives, John M. Sowa

Theses and Dissertations

Pollution is one of the greatest concerns with pulverized coal combustion. With tightening standards on pollution emissions, more information is needed to create better design models. Burner modifications are the most efficient changes that can be made to assure sufficient carbon burnout and low NOx emissions. Experiments were performed in the BYU Flat Flame Burner (FFB) lab, operating under fuel rich conditions for pyrolysis experiments and fuel lean conditions for char oxidation experiments. Effects of temperature, coal rank, residence time, and post flame oxygen content on mass release, nitrogen release, and reactivity were examined. Elemental and Inductively coupled plasma (ICP) …

Go to article

Performance Of A Full-Scale Lateral Foundation With Fine And Coarse Gravel Backfills Subjected To Static, Cyclic, And Dynamic Lateral Loads, Joshua M. Pruett Nov 2009

Performance Of A Full-Scale Lateral Foundation With Fine And Coarse Gravel Backfills Subjected To Static, Cyclic, And Dynamic Lateral Loads, Joshua M. Pruett

Theses and Dissertations

Full-scale lateral load tests were performed on a pile cap with five backfill conditions: no backfill, densely compacted fine gravel, loosely compacted fine gravel, densely compacted coarse gravel, and loosely compacted coarse gravel. Static loads, applied by hydraulic load actuators, were followed by low-frequency, actuator-driven cyclic loads as well as higher frequency dynamic loads from an eccentric mass shaker. Passive resistance from the backfill significantly increased the lateral capacity of the pile cap. Densely compacted backfill materials contributed about 70% of the total system resistance, whereas loosely compacted backfill materials contributed about 40%. The mobilized passive resistance occurred at displacement-to-height …

Go to article

A Study Of Electricians' Preferences Of Pvc And Alternative Conduit Materials In The State Of Utah, Robert Andrus Nov 2009

A Study Of Electricians' Preferences Of Pvc And Alternative Conduit Materials In The State Of Utah, Robert Andrus

Theses and Dissertations

Polyvinyl Chloride, commonly known as PVC is a common and effective construction material. PVC is also one of the most common types of plastic. In 2008, global production and consumption of PVC was approximately 34.5 million tons. The construction industry is responsible for about 70% of the world's consumption of PVC. The largest construction use of PVC is for pipe and conduit. Modern construction, especially structures built for data services depend heavily upon PVC conduit for underground pathways to distribute electricity and data. PVC is also at the center of a fierce effort by environmental groups who would like to …

Go to article

Impact Of Large Gravity Loads On Buckling Restrained Braced Frame Performance, Mark Thurgood Matthews Nov 2009

Impact Of Large Gravity Loads On Buckling Restrained Braced Frame Performance, Mark Thurgood Matthews

Theses and Dissertations

The Buckling Restrained Braced Frame (BRBF) is used in steel structures as a lateral load resisting system for seismic events. In typical design procedure the impact of gravity loads acting on BRBFs is neglected and the beams and columns of the structure are designed to resist all gravity loads. In actuality BRBFs are supporting portions of gravity loads acting on the structure which may be changing the overall performance of BRBFs. The purpose of this study is to determine the impact of large gravity loads on BRBF performance. This is done using finite element analysis to test two different structures …

Go to article

An Improved Cube Cell Assembly For The Use With High Pressure/High Temperature Cubic Apparatus In Manufacturing Polycrystalline Diamond Compact Inserts, Kevin Christian Bach Nov 2009

An Improved Cube Cell Assembly For The Use With High Pressure/High Temperature Cubic Apparatus In Manufacturing Polycrystalline Diamond Compact Inserts, Kevin Christian Bach

Theses and Dissertations

The goal for this research was to reduce the current manufacturing cost of the polycrystalline diamond compact (PDC) inserts utilized in the natural gas and oil drilling industry while not reducing their current performance. Polycrystalline Diamond is added to the tungsten-carbide (WC) substrates commonly utilized in these applications because of its greater wear and thermal resistance. With the current cube cell design for the high-pressure/high-temperature apparatus, it is necessary to bond an extra WC substrate to the polycrystalline diamond insert to achieve the sizes generally ordered by the customers. The problem of bonding the extra WC substrate was solved by …

Go to article

Vision-Based Precision Landings Of A Tailsitter Uav, Paul Travis Millet Nov 2009

Vision-Based Precision Landings Of A Tailsitter Uav, Paul Travis Millet

Theses and Dissertations

We present a method of performing precision landings of a vertical take-off and landing (VTOL) unmanned air vehicle (UAV) with the use of an onboard vision sensor and information about the aircraft's orientation and altitude above ground level (AGL). A method for calculating the 3-dimensional location of the UAV relative to a ground target of interest is presented as well as a navigational controller to position the UAV above the target. A method is also presented to prevent the UAV from moving in a way that will cause the ground target of interest to go out of view of the …

Go to article

Mechanical Structures Resisting Anterior Instability In A Computational Glenohumeral Joint Model, Kevin Elmore Nov 2009

Mechanical Structures Resisting Anterior Instability In A Computational Glenohumeral Joint Model, Kevin Elmore

Theses and Dissertations

The glenohumeral joint is the most dislocated joint in the body due to the lack of bony constraints and dependence on soft tissue, primarily muscles and ligaments, to stabilize the joint. The goal of this study was to develop a computational model of the glenohumeral joint whereby joint behavior was dictated by articular contact, ligamentous constraints, muscle loading, and external perturbations. Validation of this computational model was achieved by comparing predicted results from the model to the results of a cadaveric experiment in which the relative contribution of muscles and ligaments to anterior joint stability was examined. The results showed …

Go to article

In-Plane, All-Photonic Transduction Method For Silicon Photonic Microcantilever Array Sensors, Jong Wook Noh Nov 2009

In-Plane, All-Photonic Transduction Method For Silicon Photonic Microcantilever Array Sensors, Jong Wook Noh

Theses and Dissertations

We have invented an in-plane all-photonic transduction method for photonic microcantilever arrays that is scalable to large arrays for sensing applications in both bio- and nanotechnology. Our photonic transduction method utilizes a microcantilever forming a single mode rib waveguide and a differential splitter consisting of an asymmetric multimode waveguide and a Y-branch waveguide splitter. The differential splitter's outputs are used to form a differential signal that has a monotonic response to microcantilever deflection. A differential splitter using an amorphous silicon strip-loaded multimode rib waveguide is designed and fabricated to demonstrate the feasibility of the in-plane photonic transduction method. Our initial …

Go to article

An Evaluation Of Quikscat Uhr Wind Product's Effectiveness In Determining Selected Tropical Cyclone Characteristics, Faozi Said Nov 2009

An Evaluation Of Quikscat Uhr Wind Product's Effectiveness In Determining Selected Tropical Cyclone Characteristics, Faozi Said

Theses and Dissertations

While the standard wind product (L2B) available operationally in near-real time from SeaWinds on QuikSCAT is only 25 km in resolution, QuikSCAT data can be enhanced to yield a 2.5 km ultra-high resolution (UHR) product. The latter can be used to help estimate Tropical Cyclone (TC) characteristics such as TC eye center and wind radii. Two studies are conducted in this thesis, in which QuikSCAT UHR wind product's effectiveness in estimating these TC characteristics is evaluated. First, a comparison is made between the analyst's choice of eye location based on UHR images and interpolated best-track position. In this analysis, the …

Go to article

Gan Heterojunction Fet Device Fabrication, Characterization And Modeling, Qian Fan Nov 2009

Gan Heterojunction Fet Device Fabrication, Characterization And Modeling, Qian Fan

Theses and Dissertations

This dissertation is focused on the research efforts to develop the growth, processing, and modeling technologies for GaN-based Heterojunction Field Effect Transistors (HFETs). The interest in investigating GaN HFETs is motivated by the advantageous material properties of nitride semiconductor such as large band gap, large breakdown voltage, and high saturation velocity, which make it very promising for the high power and microwave applications. Although enormous progress has been made on GaN transistors in the past decades, the technologies for nitride transistors are still not mature, especially concerning the reliability and stability of the device. In order to improve the device …

Go to article

Variability In Construction Of Cement-Treated Base Layers: Probabilistic Analysis Of Pavement Life Using Mechanistic-Empirical Approach, Tyler J. Rogers Nov 2009

Variability In Construction Of Cement-Treated Base Layers: Probabilistic Analysis Of Pavement Life Using Mechanistic-Empirical Approach, Tyler J. Rogers

Theses and Dissertations

The primary objective of this research was to quantify the improvement in service life of a flexible pavement constructed using full-depth reclamation (FDR) in conjunction with cement stabilization when specified reductions in the spatial variability of specific construction-related parameters are achieved. This study analyzed pavement data obtained through field and laboratory testing of a reconstruction project in northern Utah. Data analyses included multivariate regression, Monte Carlo simulation, and mechanistic-empirical analyses of a model pavement structure. The results of the research show a steadily increasing trend in 28-day unconfined compressive strength of the cement-treated base (CTB) layer with increasing reductions in …

Go to article

Automated Calibration Of The Gssha Watershed Model: A Look At Accuracy And Viability For Routine Hydrologic Modeling, Kayson M. Shurtz Nov 2009

Automated Calibration Of The Gssha Watershed Model: A Look At Accuracy And Viability For Routine Hydrologic Modeling, Kayson M. Shurtz

Theses and Dissertations

The goal of hydrologic models is to accurately predict a future event of a given magnitude. Historic data are often used to calibrate models to increase their ability to forecast accurately. The GSSHA model is a distributed model that uses physical parameters and physics based computations to compute water flow from cell to cell based on a 2 dimensional grid. The goal of calibration is to obtain good estimates for the actual parameters of the watershed. These parameters should then transfer to other storm events of different magnitudes more easily than an empirical model. In conducting this research three watersheds …

Go to article

Slab-Coupled Optical Fiber Sensors For Electric Field Sensing Applications, Richard S. Gibson Nov 2009

Slab-Coupled Optical Fiber Sensors For Electric Field Sensing Applications, Richard S. Gibson

Theses and Dissertations

This dissertation presents the creation of slab coupled optical sensors (SCOS) for electric field sensing applications. SCOS devices utilize the benefits of an optical fiber system for high bandwidth and low electromagnetic interference. These sensors are fabricated by means of mode coupling between a small section of D-shaped optical fiber (D-fiber) with a multi-mode electro-optic slab waveguide. Electric field detection is accomplished by monitoring the behavior of the resonances, seen as transmission dips in the D-fiber transmission, as they shift with electric fields. The novelties of SCOS devices include their small compact nature, potential for sensor multiplexing and a dielectric …

Go to article

Improving Accuracy In Microwave Radiometry Via Probability And Inverse Problem Theory, Derek Lavell Hudson Nov 2009

Improving Accuracy In Microwave Radiometry Via Probability And Inverse Problem Theory, Derek Lavell Hudson

Theses and Dissertations

Three problems at the forefront of microwave radiometry are solved using probability theory and inverse problem formulations which are heavily based in probability theory. Probability theory is able to capture information about random phenomena, while inverse problem theory processes that information. The use of these theories results in more accurate estimates and assessments of estimate error than is possible with previous, non-probabilistic approaches. The benefits of probabilistic approaches are expounded and demonstrated. The first problem to be solved is a derivation of the error that remains after using a method which corrects radiometric measurements for polarization rotation. Yueh [1] proposed …

Go to article

Dilute Sulfuric Acid Pretreatment Of Switchgrass In Microwave Reactor For Biofuel Conversion: An Investigation Of Yields, Kinetics,, Oscar Martin Nov 2009

Dilute Sulfuric Acid Pretreatment Of Switchgrass In Microwave Reactor For Biofuel Conversion: An Investigation Of Yields, Kinetics,, Oscar Martin

Theses and Dissertations

Lignocellulosic materials provide a raw material source for biofuel conversion and offer several advantages over fossil fuels- usage of a renewable resource, reduced greenhouse emissions, a decreased dependence on foreign oil, and stimulation of the agricultural sector. However, a primary technological challenge in converting lignocellulosic biomass into fuel is overcoming the recalcitrance of its matrix to enzymatic hydrolysis. To overcome these problems for chemical processing, naturally occurring cellulose biomass must be pretreated before it can be further processed using enzymatic hydrolysis or bioconversion. The goal of this work was to develop a model that predicts the glucose yield (pretreatment and …

Go to article

Development Of Rapid Die Wear Test Method For Assessment Of Die Life And Performance In Stamping Of Advanced/Ultra High Strength Steel (A/Uhss) Sheet Materials, Omer Necati Cora Nov 2009

Development Of Rapid Die Wear Test Method For Assessment Of Die Life And Performance In Stamping Of Advanced/Ultra High Strength Steel (A/Uhss) Sheet Materials, Omer Necati Cora

Theses and Dissertations

Automotive companies are actively pursuing to increase the use of high-strength-lightweight alloys such as aluminum, magnesium, and advanced/ultra high-strength steels (A/UHSS) in body panel and structural part applications to achieve fuel efficiency while satisfying several environmental and safety concerns. A/UHSS sheet materials with higher strength and crashworthiness capabilities, in comparison to mild steel alloys, are considered as a near-term (i.e., ~5 years) choice of material for body and structural components due to their relatively low cost when compared with other lightweight materials such as aluminum and magnesium. However, A/UHSS materials present an increased level of die wear and springback in …

Go to article

Design And Development Of A Pvdf Sensor To Monitor Intracranial Pressure (Icp), Vivek Vijaywargi Nov 2009

Design And Development Of A Pvdf Sensor To Monitor Intracranial Pressure (Icp), Vivek Vijaywargi

Theses and Dissertations

Monitoring ICP non-invasively is a challenge. A novel method to measure ICP using actuators and sensors has been proposed where the skull is vibrated at high frequencies and the receiving signal is measured at the surface eyelid. A design of experiments approach is used to develop the sensor part of the ICP monitoring device so that gain can be maximized using factors such as area, thickness, electrode, and applied pressure. Statistical analysis showed that thickness has the biggest effect on overall gain. Numerical analysis confirmed these results. In addition, sensor packaging is optimized to minimize dampening of the signal and …

Go to article

Investigate Correlations Of Microstructures, Mechanical Properties And Fsw Process Variables In Friction Stir Welded High Strength Low Alloy 65 Steel, Lingyun Wei Nov 2009

Investigate Correlations Of Microstructures, Mechanical Properties And Fsw Process Variables In Friction Stir Welded High Strength Low Alloy 65 Steel, Lingyun Wei

Theses and Dissertations

The present study focuses on developing a relationship between process variables, mechanical properties and post weld microstructure in Friction Stir Welded HSLA 65 steel. Fully consolidated welds can be produced in HSLA 65 steel by PCBN Convex-Scrolled-Shoulder-Step-Spiral (CS4) tool over a wide range of parameters. Microstructures in the nugget center (NC) are dominated by lath bainite and a few polygonal/allotriomorphic grain boundary ferrites. FSW dependent variables are related to FSW independent variables by non-linear relationship. Heat input is identified to be the best parameter index to correlate with microstructures. With increasing heat input, the volume of bainite is reduced, the …

Go to article

Optimizing The Release And Methylation Of Bacterial Endospore Dipicolinic Acid, Aaron N. Nackos Nov 2009

Optimizing The Release And Methylation Of Bacterial Endospore Dipicolinic Acid, Aaron N. Nackos

Theses and Dissertations

Rapid, portable detection of biological threat agents such as Bacillus anthracis endospores (“spores”) is extremely important given the real and perceived threats of bioterrorism. Gas chromatography-mass spectrometry (GC-MS) is an excellent general means for chemical detection, although special sample preparation and specialized equipment are required to employ GC-MS for detecting biological agents such as spores in the field. A GC sample introduction probe consisting of a helical wire that can be retracted inside a syringe needle, called a coiled wire filament (CWF), was employed as a simple, passively-heated means to introduce the mixture of spores plus reagents for thermochemolysis methylation …

Go to article

Mechanical Behavior And Length Adaptation Of Rabbit Bladder Smooth Muscle, Atheer Almasri Oct 2009

Mechanical Behavior And Length Adaptation Of Rabbit Bladder Smooth Muscle, Atheer Almasri

Theses and Dissertations

Overactive bladder (OAB), involuntary contractions during bladder filling, is a common condition affecting 17% of the adult population worldwide, and in the U.S. ranks ahead of diabetes in a list of the 10 most common chronic disorders (Mullins 2009). Mechanical mechanisms contributing to OAB are not completely understood and because of the unique function and broad volume range of the bladder, there may be mechanical characteristics that distinguish detrusor smooth muscle (DSM) in bladder from other smooth muscles. Recent studies have shown that the length-passive tension curve in DSM exhibits adjustable passive stiffness (APS) characterized by a passive curve that …

Go to article

Sensitivity Analysis And Calibration Of The Alligator Cracking Model In The Mechanistic-Empirical Pavement Design Guide Using Regional Data, Vivek Jha Oct 2009

Sensitivity Analysis And Calibration Of The Alligator Cracking Model In The Mechanistic-Empirical Pavement Design Guide Using Regional Data, Vivek Jha

Theses and Dissertations

The models used in the mechanistic-empirical pavement design guide (M-EPDG) were calibrated using the data from all across the United States. The alligator cracking model uses traffic, material and structural data along with local and global calibration factors to calculate the number of axles to failure and the damage index. Both of which are further used to calculate the fatigue cracking in the pavement with the help of regression coefficients and calibration constants. However, as these coefficients and constants were developed using the national database, the model might not predict the fatigue behavior of the pavement accurately for a particular …

Go to article

The Design And Validation Of A Computational Rigid Body Model Of The Elbow., Edward Spratley Oct 2009

The Design And Validation Of A Computational Rigid Body Model Of The Elbow., Edward Spratley

Theses and Dissertations

The use of computational modeling is an effective and inexpensive way to predict the response of complex systems to various perturbations. However, not until the early 1990s had this technology been used to predict the behavior of physiological systems, specifically the human skeletal system. To that end, a computational model of the human elbow joint was developed using computed topography (CT) scans of cadaveric donor tissue, as well as the commercially available software package SolidWorks™. The kinematic function of the joint model was then defined through 3D reconstructions of the osteoarticular surfaces and various soft-tissue constraints. The model was validated …

Go to article

Development Of A Mechanical Cavopulmonary Assist Device For The Failing Fontan Patients, Jugal Kapadia Oct 2009

Development Of A Mechanical Cavopulmonary Assist Device For The Failing Fontan Patients, Jugal Kapadia

Theses and Dissertations

The long term objective of this research is to develop a collapsible, percutaneously inserted, axial flow blood pump to improve blood flow in the cavopulmonary circulation. Through this research, the experimental evaluation of five blood pump prototypes and hemolysis testing of one blood pump prototype were performed. All prototypes demonstrated acceptable hydraulic performance. A comparison of the experimental results with numerical predictions demonstrated a 10-20% deviation, an acceptable range per industry standard. Hemolysis testing of a four bladed adult blood pump showed plasma free hemoglobin level of 20.04 mg/dL and maximum NIH (normalized index of hemolysis) level was 0.017 g/100L. …

Go to article

Research In Information Technology: Analysis Of Existing Graduate Research, Christopher John Cole Oct 2009

Research In Information Technology: Analysis Of Existing Graduate Research, Christopher John Cole

Theses and Dissertations

Information Technology is an academic discipline that is well recognized by the academic community. There is an increasing number of schools offering degrees in Information Technology and has there is an official curriculum published with the ACM/IEEE computing Curriculum. A concern with Information Technology as an academic discipline is that it does not have a clearly defined set of research issues which are not studied by any other discipline. One way to propose this set of issues is to perform a “bottom-up” analysis and gather research in IT that has already been published. This research can then be analyzed for …

Go to article

Automated Data Import And Revision Management In A Product Lifecycle Management Environment, Brad Walton Brooks Oct 2009

Automated Data Import And Revision Management In A Product Lifecycle Management Environment, Brad Walton Brooks

Theses and Dissertations

A method has been created that addresses the issues that prohibit the conversion of product artifacts into a secure, efficient and reliable Product Lifecycle Management (PLM) environment. These issues include automatic import of data into a PLM system and revision control of such data. A test case is shown which specifically addresses these issues as they pertain to the management of both legacy and new engineering data in a PLM system.

Go to article

First Prev Next Last