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Articles 7231 - 7260 of 11510

Full-Text Articles in Engineering

Failing Drop Co2 Deposition (Desublimation) Heat Exchanger For The Cryogenic Carbon Capture Process, David William James Jun 2011

Failing Drop Co2 Deposition (Desublimation) Heat Exchanger For The Cryogenic Carbon Capture Process, David William James

Theses and Dissertations

Cryogenic carbon capture removes CO2 and other pollutants from flue and waste stream gases produced from the combustion of fossil fuels such as coal, natural gas, and oil and the production of cement. A transient, 1-dimensional numerical model was developed to study the temperature profile within a counter-current surface CO2 desublimation-falling liquid or solid heat exchanger. Effects of desublimation heat and mass transfer as well as convective and conductive heat transfer relationships were taken into account. Experiments show that CO2 can be captured on a falling spherical particle when appropriate column operating conditions are met.

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Experimental Characterization Of Baffle Plate Influence On Turbulent And Cavitation Induced Vibrations In Pipe Flow, Gavin J. Holt Jun 2011

Experimental Characterization Of Baffle Plate Influence On Turbulent And Cavitation Induced Vibrations In Pipe Flow, Gavin J. Holt

Theses and Dissertations

Turbulent and cavitation induced pipe vibration is a large problem in industry often resulting in pipe failures. This thesis provides an experimental investigation on turbulent flow and cavitation induced pipe vibration caused by sharp edged baffle plates. Due to large pressure losses across a baffle plate, cavitation can result. Cavitation can be destructive to pipe flow in the form of induced pipe wall vibration and cavitation inception. Incipient and critical cavitation numbers are design points that are often used in designing baffle plate type geometries. This investigation presents how these design limits vary with the influencing parameters by exploring a …

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Multi-Year Arctic Sea Ice Classification Using Quikscat, Aaron M. Swan Jun 2011

Multi-Year Arctic Sea Ice Classification Using Quikscat, Aaron M. Swan

Theses and Dissertations

Long term trends in Arctic sea ice are of particular interest with regard to global temperature, climate change, and industry. This thesis uses microwave scatterometer data from QuikSCAT and radiometer data to analyze intra- and interannual trends in first-year and multi-year Arctic sea ice. It develops a sea ice type classification method. The backscatter of first-year and multi-year sea ice are clearly identifiable and are observed to vary seasonally. Using an average of the annual backscatter trends obtained from QuikSCAT, a classification of multi-year ice is obtained which is dependent on the day of the year (DOY). Validation of the …

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Microstructure And Transport Properties Of Porous Li-Ion Electrodes, David E. Stephenson Jun 2011

Microstructure And Transport Properties Of Porous Li-Ion Electrodes, David E. Stephenson

Theses and Dissertations

The goal of this work is to understand the relationships between electrode microstructure and mass transport resistances. One can use this information to predict cell performance from fundamental principles. This work includes new types of particle-scale 3D models for correlating and predicting the effects of electrode microstructure on both ionic and electronic transport. The 3D models imitate the sub-micrometer-scale arrangement of active material particles, carbon, binder, and pores and use FIB/SEM images as a basis for parameterization. The 3D models are based respectively on the statistical mechanics techniques of molecular dynamics and Monte Carlo. The approach closely related to molecular …

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Hexahedral Mesh Refinement Using An Error Sizing Function, Gaurab Paudel Jun 2011

Hexahedral Mesh Refinement Using An Error Sizing Function, Gaurab Paudel

Theses and Dissertations

The ability to effectively adapt a mesh is a very important feature of high fidelity finite element modeling. In a finite element analysis, a relatively high node density is desired in areas of the model where there are high error estimates from an initial analysis. Providing a higher node density in such areas improves the accuracy of the model and reduces the computational time compared to having a high node density over the entire model. Node densities can be determined for any model using the sizing functions based on the geometry of the model or the error estimates from the …

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The Passive Load-Bearing Capacity Of The Human Lumbar Spine In The Neutral Standing Posture, Shaun B. Jeffs May 2011

The Passive Load-Bearing Capacity Of The Human Lumbar Spine In The Neutral Standing Posture, Shaun B. Jeffs

Theses and Dissertations

The human lumbar spine has been shown to support compressive loads of 1000 N in standing and walking, and up to many thousands of Newtons in strenuous activities such as lifting. The literature presents a number of biomechanical models that seek to replicate the load-carrying capacity of the spine while adhering to physiological constraints. While many of these models provide invaluable insights into the mechanisms governing spinal stability, there is a nearly universal disregard for the magnitude of the muscle forces required in the neutral standing posture. In compliance with constraints on metabolic cost and muscle fatigue, muscle activations in …

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Soap Bubbles And Solid Spheres: Collisions And Interactions, Joshua A. Bryson May 2011

Soap Bubbles And Solid Spheres: Collisions And Interactions, Joshua A. Bryson

Theses and Dissertations

Under the right conditions, a moving sphere may successfully enter, and leave, a soap bubble without rupturing that bubble. The physics behind this phenomena are not well understood, nor the limiting factors (such as sphere size, speed, etc.). This work, investigating this phenomenon using high speed photography, has produced several results which are presented. First, several distinct regimes, noted while photographing the interactions between the spheres and the bubbles, are classified and discussed. Next a probabilistic examination of the soap bubbles rupture by the moving spheres is presented. Then a conjecture for the limiting sphere sizes and speeds is presented. …

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Model-Guided Systems Metabolic Engineering Of Clostridium Thermocellum, Christopher Gowen May 2011

Model-Guided Systems Metabolic Engineering Of Clostridium Thermocellum, Christopher Gowen

Theses and Dissertations

Metabolic engineering of microorganisms for chemical production involves the coordination of regulatory, kinetic, and thermodynamic parameters within the context of the entire network, as well as the careful allocation of energetic and structural resources such as ATP, redox potential, and amino acids. The exponential progression of “omics” technologies over the past few decades has transformed our ability to understand these network interactions by generating enormous amounts of data about cell behavior. The great challenge of the new biological era is in processing, integrating, and rationally interpreting all of this information, leading to testable hypotheses. In silico metabolic reconstructions are versatile …

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The Presentation And Perception Of Virtual Textures Through A Haptic Matrix Display Device, Patrick Headley May 2011

The Presentation And Perception Of Virtual Textures Through A Haptic Matrix Display Device, Patrick Headley

Theses and Dissertations

Dynamic, refreshable tactile displays offer a method of displaying graphical information to people who are blind or visually impaired. Texture, which is already used as an effective method to present graphical information in physical tactile diagrams, conceivably constitutes the best way to present graphics through a tactile display. This thesis presents the design of a new low-cost haptic matrix display device capable of displaying graphical information through virtual textures. The perception of virtual textures through the display is examined through three main experiments. The first two experiments examine the perception of square wave gratings through the device. The final experiment …

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Development Of Physiologic Contact Models For Articular Surfaces, John Owen May 2011

Development Of Physiologic Contact Models For Articular Surfaces, John Owen

Theses and Dissertations

The superficial tangential zone (STZ) plays a significant role in normal articular cartilage’s ability to support loads and retain fluids. To date, tissue engineering efforts have not replicated normal STZ function in cartilage repairs. Finite element models were developed to examine the STZ’s role in normal and repaired articular surfaces under different contact conditions. Models were developed by incrementally adding improvements which culminated in contact loading of curved models by permeable and impermeable rigid surfaces and a normal cartilage layer. In the normal STZ, permeability was strain-dependent on volumetric strain; tension-compression nonlinearity modeled collagen behavior. Nonlinear geometry accounted for finite …

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A Novel P300 Speller With Motor Imagery Embedded In A Traditional Oddball Paradigm., Vaishnavi Karnad May 2011

A Novel P300 Speller With Motor Imagery Embedded In A Traditional Oddball Paradigm., Vaishnavi Karnad

Theses and Dissertations

A Brain Computer Interface (BCI) provides a means, to control external devices, through the electrical activity of the brain, bypassing motor movement. Recent years have seen an increase in the application of P300 cognitive potential as a control and/or communication signal for the motor restoration in paralyzed patients, such as those in the later stages of ALS (Amyotrophic lateral sclerosis). Although many of these patients are in locked-in state i.e. where motor control is not possible, their cognition is known to remain intact. The P300 speller paradigm explored in this study relying on this cognition represented by the P300 peak …

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Vapor Transport And Aerosol Dynamics In The Respiratory Airways, Geng Tian May 2011

Vapor Transport And Aerosol Dynamics In The Respiratory Airways, Geng Tian

Theses and Dissertations

Predicting vapor transport and aerosol dynamics in the respiratory airways is important for analyzing both environmental exposure and respiratory drug delivery. A large number of analytical models, computational studies, and experiments on vapor and aerosol transport in the respiratory tract have been conducted previously. However, a number of critical questions remain unanswered. In this study, computational fluid dynamics (CFD) is primarily employed with frequent comparisons to existing and new experimental data sets to address previously unanswered issues related to the transport of vapors and aerosol in the respiratory tract. The three objectives of this study are further described below. Objective …

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A Parallel Genetic Algorithm For Placement And Routing On Cloud Computing Platforms, Jacob A. Berlier May 2011

A Parallel Genetic Algorithm For Placement And Routing On Cloud Computing Platforms, Jacob A. Berlier

Theses and Dissertations

The design and implementation of today's most advanced VLSI circuits and multi-layer printed circuit boards would not be possible without automated design tools that assist with the placement of components and the routing of connections between these components. In this work, we investigate how placement and routing can be implemented and accelerated using cloud computing resources. A parallel genetic algorithm approach is used to optimize component placement and the routing order supplied to a Lee's algorithm maze router. A study of mutation rate, dominance rate, and population size is presented to suggest favorable parameter values for arbitrary-sized printed circuit board …

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Investigations On The Micro-Scale Surface Interactions At The Tool And Workpiece Interface In Micro-Manufacturing Of Bipolar Plates For Proton Exchange Membrane Fuel Cells, Mevlut Fatih Peker May 2011

Investigations On The Micro-Scale Surface Interactions At The Tool And Workpiece Interface In Micro-Manufacturing Of Bipolar Plates For Proton Exchange Membrane Fuel Cells, Mevlut Fatih Peker

Theses and Dissertations

Micro-forming studies have been more attractive in recent years because of miniaturization trend. One of the promising metal forming processes, micro-stamping, provides durability, strength, surface finish, and low cost for metal products. Hence, it is considered a prominent method for fabricating bipolar plates (BPP) with micro-channel arrays on large metallic surfaces to be used in Proton Exchange Membrane Fuel Cells (PEMFC). Major concerns in micro-stamping of high volume BPPs are surface interactions between micro-stamping dies and blank metal plates, and tribological changes. These concerns play a critical role in determining the surface quality, channel formation, and dimensional precision of bipolar …

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Investigations On The Effect Of Manufacturing On The Contact Resistance Behavior Of Metallic Bipolar Plates For Polymer Electrolyte Membrane Fuel Cells, Cabir Turan May 2011

Investigations On The Effect Of Manufacturing On The Contact Resistance Behavior Of Metallic Bipolar Plates For Polymer Electrolyte Membrane Fuel Cells, Cabir Turan

Theses and Dissertations

Polymer electrolyte membrane fuel cells (PEMFCs) have emerged as a strong and promising candidate to replace internal combustion engines (ICE) due their high efficiency, high power density and near-zero hazardous emissions. However, their commercialization waits for solutions to bring about significant cost-reductions and significant durability for given power densities. Bipolar plate (BPP) with its multi-faceted functions is one of the essential components of the PEMFC stacks. Stainless steel alloys are considered promising materials of choice for bipolar plate (BPP) applications in polymer electrolyte membrane fuel cells (PEMFC) due to their relatively low cost and commercial availability in thin sheets. Stainless …

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Advancements In The Solid-State Impact-Ionization Multiplier (Sim) Through Theory, Simulation And Design, Michael S. Johnson Apr 2011

Advancements In The Solid-State Impact-Ionization Multiplier (Sim) Through Theory, Simulation And Design, Michael S. Johnson

Theses and Dissertations

This dissertation outlines the study and development of a Solid-state Impact-ionization Multiplier (SIM). The SIM is a stand-alone current amplifier designed with optical detection systems in mind. The SIM amplifies signals utilizing impact ionization as a source of gain. The SIM is fabricated on silicon in order to take advantage of its favorable impact ionization coefficients. Utilizing silicon in impact ionization based gain devices makes low noise and high gains attainable. Because it is a stand-alone device, it can be wired to an arbitrary current source making it capable of receiving an input from photodiodes of any material. This makes …

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Design And Implementation Of An Eye Blink Controlled Human Computer Interface, Poonam Gwalani Apr 2011

Design And Implementation Of An Eye Blink Controlled Human Computer Interface, Poonam Gwalani

Theses and Dissertations

Advances in Human Computer Interface (HCI) have made this area of research important for improving the standard of living for people with disabilities. An eye blink system is presented to allow people with disabilities to control a standard computer mouse. This system is designed for people who are paralytic with no control over their arms, speech, and anyone who is restricted to only the control of eye and head movements. This system is based on infrared reflectivity to capture and analyze real time eye blink signal of the user. It uses simple economical hardware electronics to emulate the functionality of …

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The Program Pathing Trust Model For Critical System Process Authorization, Robert Dahlberg Apr 2011

The Program Pathing Trust Model For Critical System Process Authorization, Robert Dahlberg

Theses and Dissertations

Since computers are relied upon to run critical infrastructures – from nuclear power plants to electronic battlefield simulations – the concept of a “trusted” or tamperproof system has become even more important. Some applications have become so critical that it is imperative that they run as intended, without interference. The consequences of these systems not running as intended could be catastrophic. This research offers a solution for a key element for protecting these critical servers – validating process invocation sequences. The purpose of this research is to increase operating system security by detecting, validating, and enforcing process invocation sequences within …

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Experimental Study Of Liquid Squeeze-Flow As It Relates To Human Voice Production, Daniel Victor Lo Forte Apr 2011

Experimental Study Of Liquid Squeeze-Flow As It Relates To Human Voice Production, Daniel Victor Lo Forte

Theses and Dissertations

Approximately 7.5 million people suffer from voice disorders in the United States. Previous studies indicate that the quality of the fluid layer that coats the vocal folds appears to be different for people with voice disorders than for people whose voice is considered normal. These studies suggest that the composition and/or physical properties of the fluid layer may contribute to voice disorders. Despite these findings, little research has been undertaken to investigate the role of the fluid layer on voice, and in almost all cases, the fluid layer is considered to be insignificant. The purpose of this research was to …

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3d Functional Modeling Of Dbs Efficacy And Development Of Analytical Tools To Explore Functional Stn, Deepak Kumbhare Apr 2011

3d Functional Modeling Of Dbs Efficacy And Development Of Analytical Tools To Explore Functional Stn, Deepak Kumbhare

Theses and Dissertations

Introduction: Exploring the brain for optimal locations for deep brain stimulation (DBS) therapy is a challenging task, which can be facilitated by analysis of DBS efficacy in a large number of patients with Parkinson’s disease (PD). The Unified Parkinson's Disease Rating Scale (UPDRS) scores indicate the DBS efficacy of the corresponding stimulation location in a particular patient. The spatial distribution of these clinical scores can be used to construct a functional model which closely models the expected efficacy of stimulation in the region. Designs and Methods: In this study, different interpolation techniques were investigated that can appropriately model the DBS …

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Characterization Of The Initial Flow Rate Of Information During Reverse Engineering, Nicole Anderson Apr 2011

Characterization Of The Initial Flow Rate Of Information During Reverse Engineering, Nicole Anderson

Theses and Dissertations

The future of companies that are founded on the development of new and innovative products is threatened when competitors reverse engineer and imitate the products. If the original developers could predict how long it would take a competitor to reverse engineer a product, it may be possible for them to delay, if not prevent, that competitor's entry into the market. Metrics and measures have been developed that can estimate the time it would take an individual to reverse engineer a product. The main purpose of these metrics and measures is to help designers determine how quickly a competitor could reverse …

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Three-Dimensional Numerical Simulations Of Liquid Laminar Flow Over Superhydrophobic Surfaces With Post Geometries, Abolfazl Amin Apr 2011

Three-Dimensional Numerical Simulations Of Liquid Laminar Flow Over Superhydrophobic Surfaces With Post Geometries, Abolfazl Amin

Theses and Dissertations

Frictional resistance reduction of liquid flow over surfaces has recently become a more important topic of research in the field of fluid dynamics. Scientific and technological progress and continued interest in nano and micro-technology have required new developments and approaches related to reducing frictional resistance, especially in liquid flow through nano and micro-channels. The application of superhydrophobic surfaces could be very effective in achieving the desired flow through such small channels. Superhydrophobic surfaces are created by intentionally creating roughnesses on the surface and applying a uniform hydrophobic coating to the entire surface. Liquid droplet tests have revealed that because of …

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Return On Investment Analysis For Implementing Barriers To Reverse Engineering And Imitation, Darren C. Knight Apr 2011

Return On Investment Analysis For Implementing Barriers To Reverse Engineering And Imitation, Darren C. Knight

Theses and Dissertations

Reverse engineering (extracting information about a product from the product itself) is a competitive strategy for many firms and is often costly to innovators. Recent research has proven metrics for estimating the reverse engineering time and barrier and has shown that products can strategically be made more difficult to reverse engineer, thus protecting the innovator. Reverse engineering, however, is only the first phase of attempting to duplicate a product. Imitating – the process of discovering how to physically reproduce the performance of the reverse engineered product in one or more of its performance areas – is the second and final …

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Experimental Investigation Of Steel Pipe Pile To Concrete Cap Connections, Ryan S. Eastman Apr 2011

Experimental Investigation Of Steel Pipe Pile To Concrete Cap Connections, Ryan S. Eastman

Theses and Dissertations

Piles are often used to resist vertical and lateral loads when shallow foundations are inadequate or uneconomical. A critical part in designing pile foundations is the pile-to-cap connection. When a moment resisting connection is desired, reinforcement is typically used between the pile and the cap. A pile-to-cap connection with sufficient pile embedment depth, however, may provide similar results. One model that is currently used to determine the capacity of a pile-to-cap connection was developed by Marcakis and Mitchell for steel members embedded in concrete. This model considers an embedment mechanism that resists rotation at the connection. Recent testing has shown, …

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Factors Affecting The Strength Of Road Base Stabilized With Cement Slurry Or Dry Cement In Conjunction With Full-Depth Reclamation, Paul A. Dixon Apr 2011

Factors Affecting The Strength Of Road Base Stabilized With Cement Slurry Or Dry Cement In Conjunction With Full-Depth Reclamation, Paul A. Dixon

Theses and Dissertations

Full-depth reclamation (FDR) in conjunction with cement stabilization is an established practice for rehabilitating deteriorating asphalt roads. Conventionally, FDR uses dry cement powder applied with a pneumatic spreader, creating undesirable fugitive cement dust. The cement dust poses a nuisance and, when inhaled, a health threat. Consequently, FDR in conjunction with conventional cement stabilization cannot generally be used in urban areas. To solve the problem of fugitive cement dust, the use of cement slurry, prepared by combining cement powder and water, has been proposed to allow cement stabilization to be utilized in urban areas. However, using cement slurry introduces several factors …

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Nanocomposite High Displacement Strain Gauges For Use In Human-Machine Interfaces: Applications In Hand Pose Determination, Thomas B. Calkins Apr 2011

Nanocomposite High Displacement Strain Gauges For Use In Human-Machine Interfaces: Applications In Hand Pose Determination, Thomas B. Calkins

Theses and Dissertations

Conductive nanocomposites are finding many uses as multi-functional materials. One recent development involves the creation of high displacement strain gauges, which have potential applications in a variety of engineering roles. The piezoresistive nature of the gauges makes possible their strain sensing capability. The intent of this research is to show that specific High Displacement Strain Gauges can successfully be used in one human-machine interface application that will demonstrate their potential for a range of other human-machine interface applications. This will be shown in the development of these sensors to accomplish hand pose determination. The flexible and inexpensive gauges are attached …

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Field Algae Measurements Using Empirical Correlations At Deer Creek Reservoir, Ryan A. Stephens Apr 2011

Field Algae Measurements Using Empirical Correlations At Deer Creek Reservoir, Ryan A. Stephens

Theses and Dissertations

Deer Creek Reservoir in Utah has a history of high algae concentrations. Despite recent nutrient reduction efforts, seasonal algae continue to present problems. Cost effective, accurate, and comprehensive monitoring is important to understand the reservoir processes driving this problem and characterizing the algae spatial and temporal distributions are an important part of this effort. Current laboratory methods for accurately measuring algae are expensive and time consuming and are based on water samples taken in the field and transported to the laboratory. This approach only provides data for relatively few point samples because of the time and expense of sample collection …

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Modeling, Design, And Testing Of An Underwater Microactuation System Using A Standard Mems Foundry Process, Gregory L. Holst Apr 2011

Modeling, Design, And Testing Of An Underwater Microactuation System Using A Standard Mems Foundry Process, Gregory L. Holst

Theses and Dissertations

This work presents the modeling, design, and testing of an underwater microactuation system. It is composed of several thermomechanical in-plane microactuators (TIM) integrated with a ratchet system to provide long displacements and high forces to underwater microelectromechanical systems (MEMS). It is capable of actuating a 200µN load 110µm. It is a two-layer silicon MEMS device fabricated with a MEMS fabrication process, PolyMUMPS. This work also shows the development of an elliptic integral model to analyze the compliant fixed-guided beams in the TIM and gives new insight into the buckling behavior, reaction forces, and displacement of the beams. The derivation, verification, …

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A Multifaceted Sedimentological Analysis On Hobble Creek, Andrew S. Dutson Apr 2011

A Multifaceted Sedimentological Analysis On Hobble Creek, Andrew S. Dutson

Theses and Dissertations

Due to the endangerment of the June sucker (Chasmistes liorus), the lower two miles of Hobble Creek, Utah has been the focus of several restoration efforts. The portion of the creek between Interstate 15 and Utah Lake has been moved into a more "natural" channel and efforts are now being made to expand restoration to the east side of the freeway. This thesis reports on three different parts of a sedimentological analysis performed on Hobble Creek. The first part is a data set that contains information about the particle size distribution on the bed of Hobble Creek between …

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An Analysis Of Analytical Methods To Produce A Varying Angular Output From A Constant Angular Input Using Gearsets, Isaac R. Jones Apr 2011

An Analysis Of Analytical Methods To Produce A Varying Angular Output From A Constant Angular Input Using Gearsets, Isaac R. Jones

Theses and Dissertations

Research in developing a Positively Engaged Continuously Variable Transmission (PECVT) has been underway at Brigham Young University for some time. The inherent problems associated with embodiments of this type of transmission, namely the Non-Integer Tooth Problem (NITP), have been identified. This research is focused on the development of a Positively Engaged Piecewise Continuous Transmission (PEPCT), which is a subset of the PECVT. This document describes the hypothesis and analysis of using non-circular gearsets to overcome the NITP. This proposed solution enables a varying angular output from a constant angular input. In this research two analytical methods were evaluated based on …

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