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Articles 4111 - 4140 of 4850

Full-Text Articles in Engineering

Design Of Compact Polymer Mach-Zender Interferometer And Ring Resonator With Air Trench Structures, Seunghyun Kim, Jianhua Jiang, Gregory P. Nordin May 2006

Design Of Compact Polymer Mach-Zender Interferometer And Ring Resonator With Air Trench Structures, Seunghyun Kim, Jianhua Jiang, Gregory P. Nordin

Faculty Publications

We discuss the design of a compact ring resonator (RR) and Mach-Zehnder interferometer (MZI) in a low-refractive-index-contrast waveguide material system through the use of air trenches. A narrow air trench at the intersection of one input and two output waveguides can function as a high-efficiency splitter, while wider air trenches operate as waveguide bends. We first discuss the design of individual splitters and bends and then show how they can be used to realize a compact MZI and RR. The RR has a footprint of only 70 X 100 um, and its optical efficiency at the drop wavelengths is 86%. …

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In-Situ Testing Of A Carbon/Epoxy Isotruss Reinforced Concrete Foundation Pile, Sarah Richardson Apr 2006

In-Situ Testing Of A Carbon/Epoxy Isotruss Reinforced Concrete Foundation Pile, Sarah Richardson

Theses and Dissertations

This thesis focuses on the field performance of IsoTruss®-reinforced concrete beam columns for use in driven piles. Experimental investigation included one instrumented carbon/epoxy IsoTruss®-reinforced concrete pile (IRC pile) and one instrumented steel-reinforced concrete pile (SRC pile) which were driven into a clay profile at a test site. These two piles, each 30 ft (9 m) in length and 14 in (36 cm) in diameter, were quasi-statically loaded laterally until failure. Behavior was predicted using three different methods: 1) a commercial finite difference-based computer program called Lpile; 2) a Winkler foundation model; and, 3) a simple analysis based on fundamental mechanics …

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Increasing Speed Limit Compliance In Reduced-Speed School Zones, Kelly Grant Ash Apr 2006

Increasing Speed Limit Compliance In Reduced-Speed School Zones, Kelly Grant Ash

Theses and Dissertations

Reduced-speed school zones greatly improve the safety of young children commuting to and from school and provide larger gaps in traffic for children to cross the street. The main focus of this study was to determine effective methods for increasing speed compliance in reduced-speed school zones. This objective was accomplished through an in-depth literature review, a public opinion survey of Utah drivers, and an evaluation of the effects of speed monitoring displays (SMDs) in school zones. The main focus of the literature review was to determine how to increase and maintain speed limit compliance within school zones. Information about the …

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Forest Fire Monitoring Using Multiple Unmanned Air Vehicles, Timothy Mclain, Randal W. Beard, Ryan S. Holt, Joseph W. Egbert, Justin M. Bradley, Clark N. Taylor Apr 2006

Forest Fire Monitoring Using Multiple Unmanned Air Vehicles, Timothy Mclain, Randal W. Beard, Ryan S. Holt, Joseph W. Egbert, Justin M. Bradley, Clark N. Taylor

Faculty Publications

The ability to gather and process information on the condition of forest fires is essential to fighting the fires in a cost-effective, safe, and efficient manner. While high-altitude, long-endurance (HALE) unmanned air vehicles (UAVs) are currently used for fire surveillance; they are an expensive and scarce resource. As a proposed alternative, low-altitude, short-endurance (LASE) UAVs offer lower costs, quicker response times, and high- resolution information. In recent years, advances in solid-state sensor and autopilot technology have made LASE UAVs a feasible alternative. This paper overviews a current research project conducted by Brigham Young University and NASA Ames. In the project, …

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Assessing The Economic Impacts Of Transportation Improvement Projects, Andrew L. Stewart Mar 2006

Assessing The Economic Impacts Of Transportation Improvement Projects, Andrew L. Stewart

Theses and Dissertations

In that a transportation system can influence an economy for good or bad a system that enhances economic vitality becomes a crucial element in maintaining or developing economic prosperity. To provide a methodology to include economic development impacts of transportation improvement projects in the decision making process and the tools and alternatives available are here explored. Primary contributions of this document are results of a literature review, transportation professional and decision maker survey, economic modeling tool evaluation, and development of approach alternatives. The following thesis introduces the purpose and need for the given research, the procedure that was followed, the …

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Full Scale Static Lateral Load Test Of A 9 Pile Group In Sand, Dustin Shaun Christensen Mar 2006

Full Scale Static Lateral Load Test Of A 9 Pile Group In Sand, Dustin Shaun Christensen

Theses and Dissertations

Much research has been done to study the effects of spacing in laterally loaded pile groups and how the pile spacing affects lateral resistance of the piles. In this test a 9-pile group of steel piles was installed in a 3x3 configuration in sand. The piles were spaced from center-to-center at a distance of 5.65 pile diameters in the direction of the load. The pile group was laterally loaded and instrumented to collect deflection, load, and strain data. A separate single pile was similarly instrumented and tested for comparison to the pile group. The soil profile consisted of a top …

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Full-Scale-Lateral-Load Test Of A 1.2 M Diameter Drilled Shaft In Sand, Amy Jean Taylor Mccall Mar 2006

Full-Scale-Lateral-Load Test Of A 1.2 M Diameter Drilled Shaft In Sand, Amy Jean Taylor Mccall

Theses and Dissertations

The soil-structure interaction models associated with laterally loaded deep foundations have typically been based on load tests involving relatively small diameter foundations. The lateral soil resistance for larger diameter foundations has been assumed to increase linearly with diameter; however, few, if any load tests have been performed to confirm this relationship. To better understand the lateral resistance of large diameter deep foundations in sand, a series of full scale, cyclic, lateral load tests were performed on two 1.2 m diameter drilled shafts and a 0.324 m diameter steel pipe pile in sand. Although the tests involve two different foundation types, …

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The Storage Of Parametric Data In Product Lifecycle Management Systems, Jonathan Gary Lund Mar 2006

The Storage Of Parametric Data In Product Lifecycle Management Systems, Jonathan Gary Lund

Theses and Dissertations

Product development companies are continually seeking methods to increase efficiency while maintaining quality. Distributed development is also more important than ever before as industries globalize. These forces have driven firms to adopt formal data management practices that allow groups and individuals to work from singular, centralized data source that are secure, reliable, and support collaboration. This thesis proposes a methodology to leverage globalized infrastructures for the efficient storage of product variations. The methodology is proved through a working prototype using the market leader in Product Lifecycle Management (PLM) systems, Teamcenter Engineering. First, paradigms are set forth for the storage of …

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Development Of A Strain Energy Storage Mechanism Using Tension Elements To Enhance Golf Club Performance, Marc A. Whitezell Mar 2006

Development Of A Strain Energy Storage Mechanism Using Tension Elements To Enhance Golf Club Performance, Marc A. Whitezell

Theses and Dissertations

The development of current golf club designs has followed an evolutionary process starting with the original wooden heads of a hundred years ago, to the thin-walled, hollow body titanium heads of today. Current designs utilize what has become known as the trampoline effect to increase the efficiency of the ball-club impact, which has a number of limiting factors that restrict clubhead performance. These limitations provided the motivation for this research to explore new mechanisms by which the efficiency of the ball club impact could be increased. In particular this research focuses on the development of compliant mechanisms to increase club …

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Improving Steering Module Efficiency For Incremental Loading Finite Element Numeric Models, Ryan L. Kitchen Mar 2006

Improving Steering Module Efficiency For Incremental Loading Finite Element Numeric Models, Ryan L. Kitchen

Theses and Dissertations

Engineers frequently use computerized numeric models to calculate and predict water levels and current patterns for rivers, bays, and other bodies of water. This computation often involves an iterative process known as incremental loading that can cause frustration and consume a lot of time. Although the steering module in the Surface-water Modeling System (SMS) automates incremental loading to minimize user interaction, it can still be very time consuming. This thesis examines the steering module and the incremental loading process to improve its efficiency. Specifically, the RMA2 and FESWMS models are utilized. Two methods of improving efficiency are examined. The first …

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Solid-State Impact-Ionization Multiplier, Hong-Wei Lee Mar 2006

Solid-State Impact-Ionization Multiplier, Hong-Wei Lee

Theses and Dissertations

This dissertation presents an innovative solid-state current amplifier based on impact-ionization. Unlike avalanche photodetectors which use the same amplification principle, this device can be integrated with any external current source. A discrete amplifier was built on a silicon surface using standard CMOS fabrication processes including lithography, oxidation, ion implantation, diffusion, chemical wet etching, metal deposition, annealing, and rapid thermal processing. Testing was performed by connecting the device to a silicon photodiode, indium-gallium-arsenide photodiodes, and a function generator to demonstrate its compatibility with arbitrary current sources. Current gains above 100 along with pre-amplified leakage currents of less than 10 nA were …

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Human Interfaces For Cooperative Control Of Multiple Vehicle Systems, Jisang Sun Mar 2006

Human Interfaces For Cooperative Control Of Multiple Vehicle Systems, Jisang Sun

Theses and Dissertations

This thesis presents a human interface which helps users efficiently allocate multiple unmanned ground vehicles (UGVs) cooperating to accomplish timing-sensitive missions in an urban environment. The urban environment consists of obstacles and a hazardous region. The obstacles represent a "no-go zone" while the hazardous region represents a high-risk area. The main object of this problem is to minimize the team operational cost while satisfying timing constraints. Operational costs for individual vehicles are based on risk and power consumption, and are calculated using path length and vehicle velocity. In this thesis, three types of timing constraints are considered: simultaneous arrival, tight …

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Encryption Of Computer Peripheral Devices, Kelly Robert Norman Mar 2006

Encryption Of Computer Peripheral Devices, Kelly Robert Norman

Theses and Dissertations

Computer peripherals, such as keyboards, scanners, printers, cameras, and Personal Data Assistants (PDAs) typically communicate with a host PC via an unencrypted protocol, leaving them vulnerable to eavesdropping techniques, such as keyloggers. An encryption system was developed that is simple enough to be used in peripherals that do not have large amounts of processing power and memory. A software driver loaded in the operating system of the host computer communicates with a simple 8-bit microcontroller in the peripheral device. The driver handles key generation, key exchange, and provides decrypted data to the operating system. A key exchange protocol allows the …

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Cracking And Roughness Of Asphalt Pavements Constructed Using Cement-Treated Base Materials, Jonathan Russell Hanson Mar 2006

Cracking And Roughness Of Asphalt Pavements Constructed Using Cement-Treated Base Materials, Jonathan Russell Hanson

Theses and Dissertations

While cement treatment is a proven method for improving the strength and durability of soils and aggregates, cement hydration causes shrinkage strains in the cement-treated base (CTB) that can lead to reflection cracking in asphalt surfaces. Cracking may then cause increased pavement roughness and lead to poor ride quality. The overall purpose of this research was to utilize data collected through the Long-Term Pavement Performance (LTPP) program to investigate the use and classification of CTB layers and evaluate the relative impact of cement content on the development of roughness and cracking in asphalt concrete (AC) pavements constructed using CTB layers. …

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Effect Of Co On No And N2o Conversions In Nonthermal Argon Plasma, Morris D. Argyle, Gui-Bing Zhao, Maciej Radosz Mar 2006

Effect Of Co On No And N2o Conversions In Nonthermal Argon Plasma, Morris D. Argyle, Gui-Bing Zhao, Maciej Radosz

Faculty Publications

200-600 ppm of CO inhibit NO conversion in nonthermal Ar plasma, but do not produce N2O. However, 1.01% of CO has no effect on NO conversion, but produces N2O. In general, N2O conversion in Ar plasma decreases with increasing CO concentration. These experimental results cannot be explained by charge transfer reactions of Ar+. Selectivity analysis of all excited states of Ar possibly contributing to NOX conversion without and with CO suggests that only AR(3P2) contributes to NOX conversion and CO dissociation. A kinetic model of 43 reactions is required to model NO Conversion or N2O conversion in Ar without CO, …

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The Art And Science Of Discontinuous Innovation: A Case Study In Product Reinvention, Daniel C. Smoot Mar 2006

The Art And Science Of Discontinuous Innovation: A Case Study In Product Reinvention, Daniel C. Smoot

Theses and Dissertations

Divergence of new and old technologies is a source of tremendous innovation potential. As the dizzying pace of technological innovation accelerates indefinitely into tomorrow, not only do new paths diverge exponentially; doors already opened are increasingly abandoned for the allure of things undiscovered. Mature, late-stage life-cycle products left behind in today's fast-paced world open the floodgates to reinvention. This paper tests the hypothesis that innovativeness can be encouraged through the learning and application of universal innovation principles and processes. The implications of this research area are far-reaching. If innovation can be encouraged, then it can likely be taught. If it …

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The Role Of The Architect: Changes Of The Past, Practices Of The Present, And Indications Of The Future, Chad B. Jones Mar 2006

The Role Of The Architect: Changes Of The Past, Practices Of The Present, And Indications Of The Future, Chad B. Jones

Theses and Dissertations

For centuries the architect was the master builder; the one who was responsible for both the design and the construction of a project with sufficient construction expertise to oversee the project from inception to completion. Eventually, complexity of projects required a higher level of specialization leading to the separation of the designer and the builder. Since that separation, the role of the designer, or architect, has continued to shift and evolve. In recent history, the architect has been the one selected by a building owner, at the inception of the project, as the professional who is able to assist and …

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Automated Manipulation For The Lotus Filament Winding Process, Jeffrey V. Anderson Mar 2006

Automated Manipulation For The Lotus Filament Winding Process, Jeffrey V. Anderson

Theses and Dissertations

The filament-winding process produces quality consistent composite parts for many industries. Filament winding allows for consistent quality parts by automating the winding process. A recent development of filament winding is the Lotus process. The Lotus process reverses conventional filament winding by leaving the mandrel stationary and winding composite fiber around the mandrel. The automated Lotus filament-winding machine is controlled by four-axis control manipulating the Lotus ring around a fixed mandrel. This allows Lotus filament winding to wind parts that do not have a linear axis. Lotus filament winding is in its early stages of development. As a second step in …

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Flight Testing Small, Electric Powered Unmanned Aerial Vehicles, Jon N. Ostler Mar 2006

Flight Testing Small, Electric Powered Unmanned Aerial Vehicles, Jon N. Ostler

Theses and Dissertations

Flight testing methods are developed to find the drag polar for small UAVs powered by electric motors with fixed-pitch propellers. Wind tunnel testing was used to characterize the propeller-motor efficiency. The drag polar was constructed using data from flight tests. The proposed methods were implemented for a small UAV. A drag polar was found for this aircraft with CDo equal to 0.021, K1 equal to 0.229, and K2 equal to -0.056. This drag polar was then used to find the following performance parameters; maximum velocity, minimum velocity, velocity for maximum range, velocity for maximum endurance, maximum rate of climb, maximum …

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Analysis Of Viscous Drag Reduction And Thermal Transport Effects For Microengineered Ultrahydrophobic Surfaces, Jason W. Davies Mar 2006

Analysis Of Viscous Drag Reduction And Thermal Transport Effects For Microengineered Ultrahydrophobic Surfaces, Jason W. Davies

Theses and Dissertations

One approach recently proposed for reducing the frictional resistance to liquid flow in microchannels is the patterning of micro-ribs and cavities on the channel walls. When treated with a hydrophobic coating, the liquid flowing in the microchannel wets only the top surfaces of the ribs, and does not penetrate into the cavities, provided the pressure is not too high. The net result is a reduction in the surface contact area between channel walls and the flowing liquid. For micro-ribs and cavities that are aligned normal to the channel axis (principal flow direction), these micropatterns form a repeating, periodic structure. This …

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Two Dimensional Friction Stir Welding Model With Experimental Validation, Charles Blake Owen Mar 2006

Two Dimensional Friction Stir Welding Model With Experimental Validation, Charles Blake Owen

Theses and Dissertations

The performance of a coupled viscoplastic model of FSW has been evaluated over a variety of tool RPMs and feed rates. Initial results suggested that further optimization of the material parameters and an additional ability to model the thermal recovery of the material would improve the overall performance of the model. Therefore, an experimental/numeric approach was taken to improve and quantitatively compare the performance of the model based upon the thermal profile of the workpiece. First, an experimental method for obtaining real-time temperature measurements during Friction Stir Processing (FSP) of 304L Stainless Steel was developed. The focus of the method …

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Medium Access Control And Networking Protocols For The Intra-Body Network, Eric Thomas Stucki Mar 2006

Medium Access Control And Networking Protocols For The Intra-Body Network, Eric Thomas Stucki

Theses and Dissertations

Biomedical applications offer an exciting growth opportunity for wireless sensor networks. However, radio frequency communication is problematic in hospital environments that are susceptible to interference in the industrial, scientific, and medical (ISM) bands. Also, RF is inherently insecure as eavesdroppers can easily pick up signals. The Intra-Body Network (IBNet) proposes a novel communication model for biomedical sensor networks. It seeks the convenience of wireless communication while avoiding interference and privacy concerns associated with RF. IBNet's solution is to utilize a subject's own body tissue as a transmission medium. Assuming that transmissions are contained within the body, IBNet solves otherwise complex …

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Automatic Geometric Data Migration Throughout Views Of A Model Fidelity Family, Hans L. Soderquist Mar 2006

Automatic Geometric Data Migration Throughout Views Of A Model Fidelity Family, Hans L. Soderquist

Theses and Dissertations

Changes in geometric model parameters are constant throughout the design process. Each group in an organization needs different model information at varying times during the design process. As a result many different models of the same part or assembly arise for the needs and use of each group in each design phase (from conceptual design to full product definition). When one group makes changes to a model, those changes need to be reflected in all of the models which describe the product in all groups and design phases in order for those changes to be verified against all design criteria …

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Learning Real-Time A* Path Planner For Unmanned Air Vehicle Target Sensing, Jason K. Howlett, Timothy W. Mclain, Michael A. Goodrich Mar 2006

Learning Real-Time A* Path Planner For Unmanned Air Vehicle Target Sensing, Jason K. Howlett, Timothy W. Mclain, Michael A. Goodrich

Faculty Publications

This paper presents a path planner for sensing closely-spaced targets from a fixed-wing unmanned air vehicle (UAV) having a specified sensor footprint. The planner is based on the learning real-time A* (LRTA*) search algorithm and produces dynamically feasible paths that accomplish the sensing objectives in the shortest possible distance. A tree of candidate paths that span the area of interest is created by assembling primitive turn and straight sections of a specified step size in a sequential fashion from the starting position of the UAV. An LRTA* search of the tree produces feasible paths any time during its execution and …

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Piezoresistive Feedback For Decreased Response Time Of Mems Thermal Actuators, Robert K. Messenger, Timothy W. Mclain, Larry L. Howell Mar 2006

Piezoresistive Feedback For Decreased Response Time Of Mems Thermal Actuators, Robert K. Messenger, Timothy W. Mclain, Larry L. Howell

Faculty Publications

Feedback control is commonly used in positioning systems to improve dynamic response, disturbance rejection, accuracy, and repeatability. Similar benefits can be expected for microelectromechanical systems (MEMS) that are used for positioning applications. Sensing at the micro level poses significant challenges. Most of these challenges are associated with the small size of the devices and the small motions and forces which are of interest. In many situations, applying the macro system paradigm, where the sensor is a component that is added to the system, leads to unacceptable results. At the macro level, sensors are typically small relative to the systems they …

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Variation Analysis Of Involute Spline Tooth Contact, Brian J. De Caires Feb 2006

Variation Analysis Of Involute Spline Tooth Contact, Brian J. De Caires

Theses and Dissertations

The purpose of this thesis is to provide an in-depth understanding of tooth engagement in splined couplings based on variations in clearances between mating teeth. It is standard practice to assume that 25-50% of the total spline teeth in a coupling are engaged due to variations from manufacture. Based on the assumed number of teeth engaged, the load capability of a splined coupling is determined. However, due to the variations in tooth geometry from manufacuture, the number of teeth actually engaged is dependent on the applied load and the tooth errors. The variations result in sequential tooth engagement with increasing …

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A Plastic-Based Thick-Film Li-Ion Microbattery For Autonomous Microsensors, Qian Lin Feb 2006

A Plastic-Based Thick-Film Li-Ion Microbattery For Autonomous Microsensors, Qian Lin

Theses and Dissertations

This dissertation describes the development of a high-power, plastic-based, thick-film lithium-ion microbattery for use in a hybrid micropower system for autonomous microsensors. A composite porous electrode structure and a liquid state electrolyte were implemented in the microbatteries to achieve the high power capability and energy density. The use of single-walled carbon nanotubes (SWNTs) was found to significantly reduce the measured resistance of the cathodes that use LiAl0.14Mn1.86O4 as active materials, increase active material accessibility, and improve the cycling and power performance without the need of compression. Optimized uncompressed macro cathodes were capable of delivering power densities greater than 50 mW/cm2, …

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The Comet Assay To Determine The Mode Of Cell Death For The Ultrasonic Delivery Of Doxorubicin To Human Leukemia (Hl-60 Cells) From Pluronic P105 Micelles, Ghaleb A. Husseini, Kim L. O'Neill, William G. Pitt Feb 2006

The Comet Assay To Determine The Mode Of Cell Death For The Ultrasonic Delivery Of Doxorubicin To Human Leukemia (Hl-60 Cells) From Pluronic P105 Micelles, Ghaleb A. Husseini, Kim L. O'Neill, William G. Pitt

Faculty Publications

This notes examines the mode of cell death of HL-60 cells exposed to 70 kHz and 1.3 W/cm2 in the presence of 1% Pluronic P105 and 1.67 μg/ml doxorubicin (Dox). The cells were ultrasonicated for 30, 60 and 120 minutes. They were then lysed, electrophorised, stained using propidium iodide, and their DNA profile captured using a fluorescent microscope. The gradual DNA damage observed and the comet tails captured after 1 and 2 hours of insonation suggest that the mode of cell killing is apoptosis.

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Settling-Time Improvements In Positioning Machines Subject To Nonlinear Friction Using Adaptive Impulse Control, Tim Hakala Jan 2006

Settling-Time Improvements In Positioning Machines Subject To Nonlinear Friction Using Adaptive Impulse Control, Tim Hakala

Theses and Dissertations

A new method of adaptive impulse control is developed to precisely and quickly control the position of machine components subject to friction. Friction dominates the forces affecting fine positioning dynamics. Friction can depend on payload, velocity, step size, path, initial position, temperature, and other variables. Control problems such as steady-state error and limit cycles often arise when applying conventional control techniques to the position control problem. Studies in the last few decades have shown that impulsive control can produce repeatable displacements as small as ten nanometers without limit cycles or steady-state error in machines subject to dry sliding friction. These …

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Remote Terrain Navigation For Unmanned Air Vehicles, Stephen R. Griffiths Jan 2006

Remote Terrain Navigation For Unmanned Air Vehicles, Stephen R. Griffiths

Theses and Dissertations

There are many applications for which small unmanned aerial vehicles (SUAVs) are well suited, including surveillance, reconnaissance, search and rescue, convoy support, and short-range low-altitude perimeter patrol missions. As technologies for microcontrollers and small sensors have improved, so have the capabilities of SUAVs. These improvements in SUAV performance increase the possibility for hazardous missions through mountainous and urban terrain in the successful completion of many of these missions. The focus of this research was on remote terrain navigation and the issues faced when dealing with limited onboard processing and limited payload and power capabilities. Additional challenges associated with canyon and …

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