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

Engineering Commons™

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

Brigham Young University

Discipline
Keyword
Publication Year
Publication
Publication Type
File Type

Articles 3691 - 3720 of 4850

Full-Text Articles in Engineering

Lamina Emergent Torsion (Let) Joint, Joseph O. Jacobsen, Guimin Chen, Larry L. Howell, Spencer P. Magleby Jul 2009

Lamina Emergent Torsion (Let) Joint, Joseph O. Jacobsen, Guimin Chen, Larry L. Howell, Spencer P. Magleby

Faculty Publications

Part of the challenge in designing compliant mechanisms is finding suitable joints that provide the needed motion and force-deflection characteristics. The Lamina Emergent Torsional (LET) Joint is presented as a compliant joint suited for applications where large angular rotation is desired, but high off-axis stiffness is not as critical. The joint is introduced and the equations necessary for determining the force-deflection characteristics are presented. Since the LET Joint can be fabricated from a single planar layer, it is well suited for macro and micro applications. Illustrative examples are provided with devices fabricated from materials as diverse as steel, polypropylene, and …

Go to article

An Investigation Of Middle School Student Interest, Perception, And Attitude Toward Technology And Engineering, Kari Marie Cook Jul 2009

An Investigation Of Middle School Student Interest, Perception, And Attitude Toward Technology And Engineering, Kari Marie Cook

Theses and Dissertations

The purpose of this study was to investigate middle school student perception and attitude toward technology and engineering and to better understand how the gender of the teacher, gender of the student, and information provided in technology classes affected their perception and attitude. To accomplish this, the Technology Attitude Scale, and the Pupil's Attitudes Toward Technology—United States assessment instruments were used to form the basis of a new survey instrument focused on technology and engineering perception, use, and interest. The new survey instrument is called the Technology and Engineering Attitude Scale (TEAS) survey. Multiple 7th grade technology engineering classes from …

Go to article

Offset Qpsk In Siso And Mimo Environments, Xiaoyu Dang Jul 2009

Offset Qpsk In Siso And Mimo Environments, Xiaoyu Dang

Theses and Dissertations

We demonstrate how the performance of offset quadrature phase-shift keying (OQPSK) and its variants of Feher-patented QPSK (FQPSK) and Shaped Offset QPSK (SOQPSK) (collectively known as the ARTM Tier-1 waveforms) in single input single output (SISO) system could change with the channel fading parameters. The bit error rate expression of offset QSPK and ATRM Tier-1 waveforms over the aeronautical telemetry multipath channel has been derived. Simulations show that for the case of a single multipath ray, the BER gets worse with increasing Γ for a fixed delay, and that the BER has a quasi-periodic property for fixed Γ and increasing …

Go to article

Obstacle Avoidance, Visual Automatic Target Tracking, And Task Allocation For Small Unmanned Air Vehicles, Jeffery Brian Saunders Jul 2009

Obstacle Avoidance, Visual Automatic Target Tracking, And Task Allocation For Small Unmanned Air Vehicles, Jeffery Brian Saunders

Theses and Dissertations

Recent developments in autopilot technology have increased the potential use of micro air vehicles (MAVs). As the number of applications increase, the demand on MAVs to operate autonomously in any scenario increases. Currently, MAVs cannot reliably fly in cluttered environments because of the difficulty to detect and avoid obstacles. The main contribution of this research is to offer obstacle detection and avoidance strategies using laser rangers and cameras coupled with computer vision processing. In addition, we explore methods of visual target tracking and task allocation. Utilizing a laser ranger, we develop a dynamic geometric guidance strategy to generate paths around …

Go to article

Radio Frequency Interference Mitigation On The Very Small Array, Alan Joseph Stemmons Jul 2009

Radio Frequency Interference Mitigation On The Very Small Array, Alan Joseph Stemmons

Theses and Dissertations

Radio astronomical synthesis imaging arrays can create images with resolution much higher than can single dish telescopes. However, one of the biggest problems that imaging arrays face is radio frequency interference (RFI). This interference corrupts signals and prevents accurate image creation. Therefore, it is necessary to remove this interference. This thesis discusses the synthesis imaging procedure and array spatial filter­ing methods to remove interference, including Multiple Sidelobe Canceller (MSC), Subspace Projection (SP), and Cross­-Subspace Projection (CSP). The CLEAN algorithm, an image restoration technique, is also discussed. Various improvements to the VSA are discussed, including upgrades to the hardware and software …

Go to article

Development Of Methods To Propagate Energy Density And Predict Farfield Directivity Using Nearfield Acoustic Holography, Scott Richard Woolston Jul 2009

Development Of Methods To Propagate Energy Density And Predict Farfield Directivity Using Nearfield Acoustic Holography, Scott Richard Woolston

Theses and Dissertations

Acoustical-based imaging systems have found merit in determining the behavior of vibrating structures. This thesis focuses on the continued development of the nearfield acoustic holography (NAH) approach. Conventional NAH consists of first measuring the pressure field on a two-dimensional conformal surface and then propagating this data back to the vibrating structure to obtain information about the source, such as the normal velocity distribution. Recent work has been done which incorporates particle velocity information into the traditional NAH measurements to reduce the number of measurements required. This advancement has made NAH a more affordable tool for acoustical imaging and sound field …

Go to article

Design And Analysis Of A Dual-Mode Cascaded-Loop Frequency Synthesizer, Xiongliang Lai Jul 2009

Design And Analysis Of A Dual-Mode Cascaded-Loop Frequency Synthesizer, Xiongliang Lai

Theses and Dissertations

A new architecture for a frequency synthesizer with adjustable output frequency range and channel spacing is introduced. It is intended for the generation of closely spaced frequency channels in the GHz range while producing minimal spurious phase noise components. The architecture employs two independent phase-locked loops that are driven in cascade by a single reference oscillator. The approach provides fine resolution and wide bandwidth as well as low phase noise and should find application in many contemporary communication systems. The synthesizer can be operated in either of two different modes: nonfractional and mini-denominator fractional modes. The architecture produces no fractional …

Go to article

An Investigation Of Utah Technology Education Teachers' Acceptance Of An Emphasis On Engineering Education Content, Douglas Ron Livingston Jul 2009

An Investigation Of Utah Technology Education Teachers' Acceptance Of An Emphasis On Engineering Education Content, Douglas Ron Livingston

Theses and Dissertations

The purpose of this study is to collect information documenting Utah technology education teachers' acceptance of an emphasis on engineering content in technology education. The Stages of Concern Questionnaire (SoCQ) was used to determine the level of acceptance of this change. It was found that a majority of technology and education teachers are more concerned about other unidentified tasks, activities or initiatives than they are about the addition of engineering content to their classes. They were also shown to be concerned with being able to organize, manage, and schedule the change effectively and were found to be least concerned about …

Go to article

Optimized Distribution Of Strength In Buckling-Restrained Brace Frames In Tall Buildings, Graham Thomas Oxborrow Jul 2009

Optimized Distribution Of Strength In Buckling-Restrained Brace Frames In Tall Buildings, Graham Thomas Oxborrow

Theses and Dissertations

Nonlinear time history analysis is increasingly being used in the design of tall steel structures, but member sizes still must be determined by a designer before an analysis can be performed. Often the distribution of story strength is still based on an assumed first mode response as determined from the Equivalent Lateral Force (ELF) procedure. For tall buckling restrained braced frames (BRBFs), two questions remain unanswered: what brace distribution will minimize total brace area, while satisfying story drift and ductility limits, and is the ELF procedure an effective approximation of that distribution? In order to investigate these issues, an optimization …

Go to article

Cross-Correlation-Based Texture Analysis Using Kinematically Simulated Ebsd Patterns, Joshua Peter Kacher Jul 2009

Cross-Correlation-Based Texture Analysis Using Kinematically Simulated Ebsd Patterns, Joshua Peter Kacher

Theses and Dissertations

The development and example applications of a new EBSD-based texture analysis system are presented. This new system uses the cross-correlation function to compare two EBSD patterns at a number of corresponding regions in each pattern to calculate the deformation gradient tensor. Bragg's Law-based simulated EBSD patterns are used as reference patterns in the cross-correlation method to enable the measurements of absolute elastic strain and lattice orientation at discrete points in a crystalline sample. The resolution limits of this new method are explored using a variety of computational and physical experiments. The simulated pattern method is estimated to be able to …

Go to article

Applications Of Variation Analysis Methods To Automotive Mechanisms, Robert C. Leishman Jun 2009

Applications Of Variation Analysis Methods To Automotive Mechanisms, Robert C. Leishman

Theses and Dissertations

Variation analysis, or tolerance analysis as it is sometimes called, is typically used to predict variation in critical dimensions in assemblies by calculating the stack-up of the contributing component variations. It is routinely used in manufacturing and assembly environments with great success. Design engineers are able to account for the small changes in dimensions that naturally occur in manufacturing processes, in equipment, and due to operators and still ensure that the assemblies will meet the design specifications and required assembly performance parameters. Furthermore, geometric variation not only affects critical fits and clearances in static assemblies, it can also cause variation …

Go to article

Evaluation Of The Benefits Of Oxy-Combustion On Emissions From A Compression Ignition Engine, Thomas A. Salt Jun 2009

Evaluation Of The Benefits Of Oxy-Combustion On Emissions From A Compression Ignition Engine, Thomas A. Salt

Theses and Dissertations

In this research the benefits of applying oxy-combustion in a diesel engine to reduce NOx and particulate emissions were evaluated. The addition of oxygen to the intake in conjunction with exhaust gas recirculation (EGR) was shown to reduce NOx without an increase in particulate. Indicated specific NOx and particulate emissions for oxygen-enhanced EGR (O-EGR) and EGR without oxygen addition (normal or N-EGR) were compared at three engine loads. NOx emissions correlated with flame temperature for both N-EGR and O-EGR but were slightly lower at a given flame temperature for O-EGR. Flame temperature reduction for N-EGR was primarily through dilution of …

Go to article

Slip Lined Culvert Retrofit And Fish Passage, Joseph Ray Webb Jun 2009

Slip Lined Culvert Retrofit And Fish Passage, Joseph Ray Webb

Theses and Dissertations

Culverts throughout the country are approaching or are past their original design lives. These ‘baby boomer’ culverts will need to be repaired, rehabilitated, or replaced. Because entire culvert replacement is so expensive and intrusive, alternate measures to extend the culvert project life are growing increasingly popular. One such method is slip lining, where a ‘sleeve’ is installed within an existing culvert barrel and stabilized. Plastic pipe sleeves are very popular for slip lining primarily because the plastic material's lower Manning's roughness values allow for the culvert capacity to be maintained despite a reduction in culvert size. Unfortunately, the reduced friction …

Go to article

Investigation Of Additives For Use In Electroless Plating Solutions For Fabrication Of Nanowires, Elliott J. Bird Jun 2009

Investigation Of Additives For Use In Electroless Plating Solutions For Fabrication Of Nanowires, Elliott J. Bird

Theses and Dissertations

This study focused on improvement of electroless plating methods by use of particular bath additives. The techniques developed here can enable us to plate very thin layers selectively on a nonconductive substrate and thus create metallized features on a nanoscale. Through the development of such bottom-up techniques this work contributes a key technology to achieving self-assembled nanocircuits. The use of additives in an electroless plating environment can modify the barriers to nucleation (or seeding) and growth. Two additives, namely 3-mercapto-1-propanesulfonic Acid (MPS) and 1,3-propanedisulfonic acid (PDS), notably increased the selectivity of electroless metallization on chemically modified surfaces, which can be …

Go to article

Automated All-Quadrilateral Mesh Adaptation Through Refinement And Coarsening, Bret D. Anderson Jun 2009

Automated All-Quadrilateral Mesh Adaptation Through Refinement And Coarsening, Bret D. Anderson

Theses and Dissertations

This thesis presents a new approach to conformal all-quadrilateral mesh adaptation. In finite element modeling applications, it is often desirable to modify the node density of the mesh; increasing the density in some parts of the mesh to provide more accurate results, while decreasing the density in other parts to reduce computation time. The desired node density is typically determined by a sizing function based on either the geometry of the model or the results of a finite element solution. Although there are numerous mesh adaptation methods currently in use, including initial adaptive mesh generation, node redistribution, and adaptive mesh …

Go to article

Dynamics And Control Of Cable-Drogue System In Aerial Recovery Of Micro Air Vehicles Based On Gauss's Principle, Liang Sun, Randal W. Beard, Mark B. Colton, Timothy W. Mclain Jun 2009

Dynamics And Control Of Cable-Drogue System In Aerial Recovery Of Micro Air Vehicles Based On Gauss's Principle, Liang Sun, Randal W. Beard, Mark B. Colton, Timothy W. Mclain

Faculty Publications

This paper presents a new concept for aerial recovery of Micro Air Vehicles (ARMAVs) using a large mothership and a recovery drogue. The mothership drags a drogue attached to a cable and the drogue is controlled to match the flight patten of the MAV. This paper uses Gauss’s Principle to derive the dynamic model of the cable-drogue systems. A controllable drogue plays a key role in recovering MAVs in windy conditions. We develop a control approach for the drogue using its drag coefficient. Simulation results based on multilink cable-drogue systems present the feasibility of the aerial recovery concept and the …

Go to article

An Internal Representation For Adaptive Online Parallelization, Koy D. Rehme May 2009

An Internal Representation For Adaptive Online Parallelization, Koy D. Rehme

Theses and Dissertations

Future computer processors may have tens or hundreds of cores, increasing the need for efficient parallel programming models. The nature of multicore processors will present applications with the challenge of diversity: a variety of operating environments, architectures, and data will be available and the compiler will have no foreknowledge of the environment until run time. Adaptive Online Parallelization (ADOPAR) is a unifying framework that attempts to overcome diver sity by separating discovery and packaging of parallelism. Scheduling for execution may then occur at run time when diversity may best be resolved. This work presents a compact representation of parallelism based …

Go to article

Frequency Response Of The Skin On The Head And Neck During Production Of Selected Speech Sounds, Jacob B. Munger May 2009

Frequency Response Of The Skin On The Head And Neck During Production Of Selected Speech Sounds, Jacob B. Munger

Theses and Dissertations

Vibration within the vocal tract during speech is transmitted through body tissue to the skin surface and can be used to transmit speech. Achieving quality speech signals using skin vibration is desirable but problematic, primarily due to the different sources of sound during speech. The objective of this study was to characterize the frequency content of speech signals at various locations on the head and neck. Signals were recorded using accelerometers attached to 15 locations on the heads and necks of 14 males and 10 females as well as a microphone to record audible speech. The subjects produced several isolated …

Go to article

Economic Development Criteria And Project Prioritization, Jason Scott Mcgee May 2009

Economic Development Criteria And Project Prioritization, Jason Scott Mcgee

Theses and Dissertations

To provide a more in-depth analysis of potential roadway projects, the Utah Department of Transportation (UDOT) desired a method of evaluating projects according to their economic potential without using potentially costly computer models or excessive data collection. Brigham Young University (BYU) was retained to research and recommend criteria for the economic development criteria in the project-prioritization process. A literature review was first undertaken to better understand the transportation-economic development relationship. Using the literature review, combined with the information from the Economic Development Corporation of Utah, the Governor's Office of Planning and Budget, the Governor's Office of Economic Development, and a …

Go to article

Understanding Performance--Limiting Mechanisms In Li-Ion Batteries For High-Rate Applications, Indrajeet Vilasrao Thorat Apr 2009

Understanding Performance--Limiting Mechanisms In Li-Ion Batteries For High-Rate Applications, Indrajeet Vilasrao Thorat

Theses and Dissertations

This work presents novel modeling and experimental techniques that provide insight into liquid-phase mass transport and electron transfer processes in lithium-ion batteries. These included liquid-phase ionic mass transport (conduction and diffusion), lithium diffuion in the solid phase and electronic transport in the solid phase. Fundamental understanding of these processes is necessary to efficiently design and optimize lithium-ion batteries for different applications. To understand the effect of electrode structure on the electronic resistance of the cathode, we tested power performance of cathodes with combinations of three different carbon conductivity additives: vapor-grown carbon fibers (CF), carbon black (CB) and graphite (GR). With …

Go to article

Real-Time Optical Flow Sensor Design And Its Application On Obstacle Detection, Zhaoyi Wei Apr 2009

Real-Time Optical Flow Sensor Design And Its Application On Obstacle Detection, Zhaoyi Wei

Theses and Dissertations

Motion is one of the most important features describing an image sequence. Motion estimation has been widely applied in structure from motion, vision-based navigation and many other fields. However, real-time motion estimation remains a challenge because of its high computational expense. The traditional CPU-based scheme cannot satisfy the power, size and computation requirements in many applications. With the availability of new parallel architectures such as FPGAs and GPUs, applying these new technologies to computer vision tasks such as motion estimation has been an active research field in recent years. In this dissertation, FPGAs have been applied to real-time motion estimation …

Go to article

Ultrasonic Drug Delivery To Tumors Via Stealth Liposomes, Peter Jones, Ghaleb A. Husseini, William G. Pitt, Beverly L. Roeder Apr 2009

Ultrasonic Drug Delivery To Tumors Via Stealth Liposomes, Peter Jones, Ghaleb A. Husseini, William G. Pitt, Beverly L. Roeder

Faculty Publications

Our research develops ultrasonically-controlled drug delivery systems. Previous micellar drug carriers released the drug upon ultrasonication. We have developed a liposomal drug carrier that is even more effective upon insonation in reducing tumors.

Go to article

Cad-Centric Dynamic Workflow Generation, Travis L. Kenworthy Apr 2009

Cad-Centric Dynamic Workflow Generation, Travis L. Kenworthy

Theses and Dissertations

CAD systems are important design tools that enable the designer to conceptualize, visualize, analyze, and manufacture a design (Shahin 2008). Although high-end CAD systems provide several built-in design applications, the users of CAD often select various custom or proprietary non-CAD analyses that constrain, optimize, or evaluate their designs. An efficient method is needed to perform trade studies from within the CAD environment. Methods have been developed to meet the challenges associated with this need. The methods have been implemented in a program, called the Process Integrator, which resides in a CAD system and allows the user to perform trade studies …

Go to article

A Numerical Model Of The Friction Stir Plunge, Stanford Wayne Mcbride Apr 2009

A Numerical Model Of The Friction Stir Plunge, Stanford Wayne Mcbride

Theses and Dissertations

A Lagrangian finite-element model of the plunge phase of the friction stir welding process was developed to better understand the plunge. The effects of both modeling and experimental parameters were explored. Experimental friction stir plunges were made in AA 7075-T6 at a plunge rate of 0.724 mm/s with spindle speeds ranging from 400 to 800 rpm. Comparable plunges were modeled in Forge2005. Various simulation parameters were explored to assess the effect on temperature prediction. These included the heat transfer coefficient between the tool and workpiece (from 0 to 2000 W/m-K), mesh size (node counts from 1,200 to 8,000), and material …

Go to article

Payload Directed Flight Of Miniature Air Vehicles, Randal W. Beard, Clark Taylor, Jeff Saunders, Ryan Holt, Timothy W. Mclain Apr 2009

Payload Directed Flight Of Miniature Air Vehicles, Randal W. Beard, Clark Taylor, Jeff Saunders, Ryan Holt, Timothy W. Mclain

Faculty Publications

This paper describes three applications of payload directed flight using miniature air vehicles: vision-based road following, vision-based target tracking, and vision-based mapping. A general overview of each application is given, followed by simulation and flight-test results. Results demonstrate the viability of utilizing electo-optical video imagery to directly control the air vehicle flight path to enhance performance relative to the sensing objective.

Go to article

Evaluation Of Full-Depth Reclamation On Strength And Durability Of Pavement Base Layers, Benjamin Earl Griggs Mar 2009

Evaluation Of Full-Depth Reclamation On Strength And Durability Of Pavement Base Layers, Benjamin Earl Griggs

Theses and Dissertations

The purpose of this research was to determine the effect of full-depth reclamation (FDR) on the strength and durability of aggregate base layers in a coordinated approach involving both field and laboratory testing. Field comparisons between the pre-reclamation neat base and post-reclamation blended base were supplemented with laboratory experiments conducted to determine the effects of reclaimed asphalt pavement (RAP) content, compaction effort, and heating on the strength and durability of roadways reconstructed using FDR with a portable asphalt recycling machine (PARM). Also, the effect of reclamation on the spatial uniformity of the pavement structures was explored by comparing variability in …

Go to article

Laser Levitation Of Solid Particles For Combustion And Gasification Applications, Skigh E. Lewis Mar 2009

Laser Levitation Of Solid Particles For Combustion And Gasification Applications, Skigh E. Lewis

Theses and Dissertations

This dissertation details theoretical and experimental work in the development of a novel combustion diagnostic: laser levitation of solid particles. Theoretical analyses of the forces involved in the suspension of solid particles in a laser beam provide a comprehensive description of the levitation mechanism. Experimental work provides extensive observations and data that describe each of the forces involved, including results from detailed models. Theoretical models establish that a free-convective drag force, light scattering, photon momentum, and other minor forces contribute to the trapping mechanism. The theory quantitatively predicts particle temperature and magnitudes of each of the forces involved. Experimental measurements …

Go to article

The Utilization Of Light Gauge Steel In Residential Construction On The State Of Utah, Matthew Zaugg Perkins Mar 2009

The Utilization Of Light Gauge Steel In Residential Construction On The State Of Utah, Matthew Zaugg Perkins

Theses and Dissertations

This thesis researched why light gauge steel framing members are not used more in single-family residential construction. A survey was designed to extract information from licensed contractors in Utah on uses of light gauge steel framing members in residential homes. The purpose of the research was to discover what Utah builder's perception was concerning light gauge steel framing. Also, the researcher tried to learn a little about the contractors to see if there was a correlation between contractors that used light gauge steel and those that did not. Names of licensed general building contractors and residential contractors and their contact …

Go to article

An Investigative Study Of The Difficulties Experienced By Engineers Transitioning Into Leadership/Management Positions, Joseph Alan Wilde Mar 2009

An Investigative Study Of The Difficulties Experienced By Engineers Transitioning Into Leadership/Management Positions, Joseph Alan Wilde

Theses and Dissertations

The traditional engineering career has been defined by two career paths: technical and managerial. An entry level engineer typically did not elect his/her career path until at least five years into a career. This meant that only a portion of engineers needed to learn management and leadership skills and then usually not until in the professional environment. Since this career distinction was not made until years into an engineer's professional life universities were not developing leadership/management skills in their students. Times have changed. With the globalization of the economy, and the increased competition in the marketplace, companies have realized that …

Go to article

Second-Order Structural Analysis With One Element Per Member, Jesse William Lyon Mar 2009

Second-Order Structural Analysis With One Element Per Member, Jesse William Lyon

Theses and Dissertations

In this thesis, formulas for the local tangent stiffness matrix of a plane frame member are derived by differentiating the member resistance vector in the displaced position. This approach facilitates an analysis using only one element per member. The formulas are checked by finite difference. The derivation leads to the familiar elastic and geometric stiffness matrices used by other authors plus an additional higher order geometric stiffness matrix. Contributions of each of the three sub-matrices to the tangent stiffness matrix are studied on both the member and structure levels through two numerical examples. These same examples are analyzed three different …

Go to article

First Prev Next Last