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Articles 2041 - 2070 of 4850

Full-Text Articles in Engineering

A Better Way To Build Plant Models, Dean Holzworth, Hamish Brown, Neil Huth Jul 2016

A Better Way To Build Plant Models, Dean Holzworth, Hamish Brown, Neil Huth

International Congress on Environmental Modelling and Software

The plant modelling framework (PMF) in the next generation of APSIM enables plant models to be constructed in a novel, more reliable and robust manner. It provides a library of small processes that can be aggregated into bigger processes which in turn can be combined into larger constructs, ultimately forming a plant model. The user interface supports a workflow that allows the model builder to collate and store experimental data, construct the model (by process aggregation), create and run simulations of the experimental data and graphically view the performance of the model. The model builder can then iteratively modify the …

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Towards Standard Variable Names For Environmental Chemistry: Semantic Mediation And Extensions To The Csdms Standard Names, Scott Dale Peckham Jul 2016

Towards Standard Variable Names For Environmental Chemistry: Semantic Mediation And Extensions To The Csdms Standard Names, Scott Dale Peckham

International Congress on Environmental Modelling and Software

When a model needs to obtain the values of its input variables from another model or from a data file, it is necessary to reliably match the internal vocabularies of the coupled resources (e.g. models or data sets). In addition, spatial regridding, time interpolation and unit conversion may be required. In order to automate this semantic matching and variable exchange process in a model coupling framework, the internal vocabularies of the resources to be coupled must be mapped to a controlled vocabulary in a hub-and-spoke manner. The CSDMS Standard Names provide a domain-independent set of conventions and rules for constructing …

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How Modellers Frame Uncertainty In Scientific Publications: Review And Reflections, Joseph H.A. Guillaume, Casey Helgeson, Sondoss Elsawah, Anthony J. Jakeman, Matti Kummu Jul 2016

How Modellers Frame Uncertainty In Scientific Publications: Review And Reflections, Joseph H.A. Guillaume, Casey Helgeson, Sondoss Elsawah, Anthony J. Jakeman, Matti Kummu

International Congress on Environmental Modelling and Software

Uncertainty is recognised as an essential issue in environmental modelling. As modellers, we notably use a variety of tools and techniques within an analysis, for example related to uncertainty quantification and model validation. We also address uncertainty by how we present results. For example, experienced modellers are careful to distinguish robust conclusions from those that need further work, and the precision of quantitative results is tailored to their accuracy. In doing so, the modeller frames how uncertainty should be interpreted by their audience. This is an area which extends beyond modelling to fields such as philosophy of science, semantics, discourse …

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Modelling Combinations Of Economic Instruments To Eliminate Depletion In The Alto Guadalentín Aquifer (Se Spain), David Martínez-Granados, Javier Calatrava Jul 2016

Modelling Combinations Of Economic Instruments To Eliminate Depletion In The Alto Guadalentín Aquifer (Se Spain), David Martínez-Granados, Javier Calatrava

International Congress on Environmental Modelling and Software

This paper analyses the cost-effectiveness of combining several policy instruments to address the problem of non-renewable pumping in the Alto Guadalentín aquifer in Southeast Spain, one of the most extreme cases of aquifer depletion in Europe. Their economic impact is assessed using a partial equilibrium non-linear mathematical programming model that maximises the farm net margin resulting from the use of the available water resources for irrigation in the area. Our results show that all the alternatives have significant economic impacts, although the future availability of desalinised resources would notably mitigate them, as farmers can substitute groundwater with desalinised water. …

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The Effects Of Antenna Coupling In A Mimo Radar System, Benjamin T. Arnold Jul 2016

The Effects Of Antenna Coupling In A Mimo Radar System, Benjamin T. Arnold

Theses and Dissertations

A mathematical model for a multiple-input multiple-output radar system is presented. The model is used to track signals through the system in order to identify the impact of antenna array mutual coupling on radar system performance. Simulations using the model provide quantitative assessment of the performance degradation as a function of antenna coupling strength. Specifically, the results show that coupling can cause a target to appear at an angle notably different than its actual angle and can cause an increase in the side lobe level. A compensation technique is presented that completely removes these effects for practical levels of coupling. …

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Simplified Performance-Based Analysis For Seismic Slope Displacements, Marlem Lucia Astorga Mejia Jul 2016

Simplified Performance-Based Analysis For Seismic Slope Displacements, Marlem Lucia Astorga Mejia

Theses and Dissertations

Millions of lives have been lost over the years as a result of the effects of earthquakes. One of these devastating effects is slope failure, more commonly known as landslide. Over the years, seismologists and engineers have teamed up to better record data during an earthquake. As technology has advanced, the data obtained have become more refined, allowing engineers to use the data in their efforts to estimate earthquakes where they have not yet occurred. Several methods have been proposed over time to utilize the earthquake data and estimate slope displacements. A pioneer in the development of methods to estimate …

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Comparison Of Airfoil Precomputational Analysis Methods For Optimization Of Wind Turbine Blades, Ryan Barrett, Andrew Ning Jul 2016

Comparison Of Airfoil Precomputational Analysis Methods For Optimization Of Wind Turbine Blades, Ryan Barrett, Andrew Ning

Faculty Publications

The objective of this research was to develop and compare various airfoil precomputational parameterization and analysis techniques for aerostructural optimization of wind turbine blades. The airfoils along the blade were added as optimization design variables through pre-computational parameterization methods using thickness-to-chord ratios and blended airfoil family factors. The airfoils' aerodynamic performance was analyzed with three methods of increasing fidelity: a panel method (XFOIL), Navier-Stokes based computational fluid dynamics (RANS CFD), and wind tunnel data. The optimizations minimized mass over annual energy production (m/AEP) and thereby approximated the minimization of cost of energy. The results were compared to the NREL 5-MW …

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Cushioned Extended-Periphery Avoidance: A Reactive Obstacle Avoidance Plugin, Timothy Mclain, James Jackson, David Wheeler Jun 2016

Cushioned Extended-Periphery Avoidance: A Reactive Obstacle Avoidance Plugin, Timothy Mclain, James Jackson, David Wheeler

Faculty Publications

While collision avoidance and flight stability are generally a micro air vehicle’s (MAVs) highest priority, many map-based path planning algorithms focus on path optimality, often assuming a static, known environment. For many MAV applications a robust navigation solution requires responding quickly to obstacles in dynamic, tight environments with non- negligible disturbances. This article first outlines the Reactive Obstacle Avoidance Plugin framework as a method for leveraging map-based algorithms while providing low-latency, high-bandwidth response to obstacles. Further, we propose and demonstrate the effectiveness of the Cushioned Extended- Periphery Avoidance (CEPA) algorithm. By representing recent laser scans in the current body-fixed polar …

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Rosflight: A Lightweight, Inexpensive Mav Research And Development Tool, Timothy Mclain, James Jackson, Gary J. Ellingson Jun 2016

Rosflight: A Lightweight, Inexpensive Mav Research And Development Tool, Timothy Mclain, James Jackson, Gary J. Ellingson

Faculty Publications

To accelerate research and development of the autonomous capabilities of micro aerial vehicles we have developed flight control framework, ROSflight, as a research tool. ROSflight makes development of autopilot code easier and more efficient by minimizing the use of embedded systems, incorporating the Robot Operating System and using off-the-shelf and open-source hardware and software. Motivation and applications for use in the research community are discussed. Analysis of loop rate and communication bandwidth are presented as well as results from flight demonstration of two multi-rotor aircraft.

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An Investigation Of The Impact A Rov Competition Curriculum Has On Student Interest In Stem, Specifically Technology And Engineering, Daniel Gordon Bates Jun 2016

An Investigation Of The Impact A Rov Competition Curriculum Has On Student Interest In Stem, Specifically Technology And Engineering, Daniel Gordon Bates

Student Works

This research investigates the impact a Remotely Operated Vehicle (ROV) program has on student interest in, and perception of, technology and engineering (sTEm). ROV programs embed areas of science, technology, engineering and math (STEM) into their curriculum; however, emphasis for this study is placed on interest and perception of the "T" and "E" of STEM. Although there are many articles detailing the benefits of ROV programs, there is little empirical data documenting the impact on student interest and perception of sTEm. This study outlines the background of a few major ROV programs in the U.S.; specifically Utah Underwater Robotics (UUR), …

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The Effect Of Projectile Nose Shape On The Formation Of The Water Entry Cavity, Jeremy Conrad Ellis Jun 2016

The Effect Of Projectile Nose Shape On The Formation Of The Water Entry Cavity, Jeremy Conrad Ellis

Theses and Dissertations

This research focuses on the effect of several convex and concave nose shapes on cavity formation for both hydrophilic and hydrophobic projectiles. It specifically investigates the effect of convex shape on the threshold velocity for cavity formation as well as the effect of concave shapes on cavity formation in terms of impact velocity, geometry of the concave shape and wettability of the projectile. For the convex cases, the streamlined axisymmetric shape significantly increases the threshold velocity when cavities form and is most pronounced for the ogive and cone. The study demonstrates that measuring the wetting angle and impact velocity is …

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Jezik: A Cognitive Translation System Employing A Single, Visible Spectrum Tracking Detector, Davor Bzik Jun 2016

Jezik: A Cognitive Translation System Employing A Single, Visible Spectrum Tracking Detector, Davor Bzik

Student Works

A link between eye movement mechanics and the mental processing associated with text reading has been established in the past. The pausing of an eye gaze on a specific word within a sentence reflects correctness or fluency of a translated text. A cognitive translation system has been built employing a single, inexpensive web camera without the use of infrared illumination. It was shown that the system translates the text, detects rarely occurring and out-of-context words from eye gaze information, and provides solutions in real time while the user is still reading. The solutions are in form of a translation, definition …

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Modeling And Control Of A Tailsitter With A Ducted Fan, Matthew Elliott Argyle Jun 2016

Modeling And Control Of A Tailsitter With A Ducted Fan, Matthew Elliott Argyle

Student Works

There are two traditional aircraft categories: fixed-wing which have a long endurance and a high cruise airspeed and rotorcraft which can take-off and land vertically. The tailsitter is a type of aircraft that has the strengths of both platforms, with no additional mechanical complexity, because it takes off and lands vertically on its tail and can transition the entire aircraft horizontally into high-speed flight. In this dissertation, we develop the entire control system for a tailsitter with a ducted fan. The standard method to compute the quaternion-based attitude error does not generate ideal trajectories for a hovering tailsitter for some …

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Non-Schmid Effects And Criteria For Dislocation Nucleation On Different Slip Systems At Grain Boundaries, Richard Durtschi Wyman Jun 2016

Non-Schmid Effects And Criteria For Dislocation Nucleation On Different Slip Systems At Grain Boundaries, Richard Durtschi Wyman

Theses and Dissertations

Criteria for grain boundary dislocation nucleation are developed. A bicrystal containing two grain boundaries is placed under varying triaxial stress states using molecular dynamics. The local resolved shear, normal, and co-slip stresses needed for grain boundary dislocation nucleation are found. A framework is developed to detect the slip system grain boundary dislocation nucleation occurs on. A survey of the different ways grain boundary dislocation nucleation occurs in the sample shows a single grain boundary can nucleate dislocations in a rich variety of ways. Using the nucleation system and resolved stress values, criteria for grain boundary dislocation nucleation on different slip …

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Duplicate With Choose: Using Statistics For Fault Mitigation, Jon-Paul Anderson Jun 2016

Duplicate With Choose: Using Statistics For Fault Mitigation, Jon-Paul Anderson

Theses and Dissertations

This dissertation presents a novel technique called duplicate with choose (DWCh) which is a modification of the fault detection technique duplicate with compare (DWC). DWCh adds a smart decider block to DWC that monitors the duplicated circuits and decides which circuit is fault free when a fault occurs. If chosen correctly, DWCh is able to mask faults at a lower cost than conventional techniques like TMR.This dissertation derives reliability expressions for DWCh showing that under ideal conditions its reliability exceeds the most commonly used fault masking technique for spacecraft, triple modular redundancy. For non-ideal conditions, DWCh provides a lower cost …

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An Investigation Of The Impact A Rov Competition Curriculum Has On Student Interest In Stem, Specifically Technology And Engineering, Daniel Gordon Bates Jun 2016

An Investigation Of The Impact A Rov Competition Curriculum Has On Student Interest In Stem, Specifically Technology And Engineering, Daniel Gordon Bates

Theses and Dissertations

This research investigates the impact a Remotely Operated Vehicle (ROV) program has on student interest in, and perception of, technology and engineering (sTEm). ROV programs embed areas of science, technology, engineering and math (STEM) into their curriculum; however, emphasis for this study is placed on interest and perception of the "T" and "E" of STEM. Although there are many articles detailing the benefits of ROV programs, there is little empirical data documenting the impact on student interest and perception of sTEm. This study outlines the background of a few major ROV programs in the U.S.; specifically Utah Underwater Robotics (UUR), …

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Optimum Pick Point Locations For Straight, Singly Symmetric Steel Plate Girders, J. Andrew Pratt Jun 2016

Optimum Pick Point Locations For Straight, Singly Symmetric Steel Plate Girders, J. Andrew Pratt

Theses and Dissertations

Optimal pick point location is discovered in order to have the full buckling capacity of a suspended, non-prismatic, singly symmetric plate girders. The results show that a significant increase in stability occurs at the pick point location of 0.25L, where L is the span length. This recommendation can be utilized in the field to save construction cost and time because of how simplistic it is to use. A finite element software, ABAQUS 6.14, is used to determine the buckling capacities at different pick point locations and of different cross sections. The dimension of the cross sections and span lengths for …

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Cooperative Estimation For A Vision-Based Multiple Target Tracking System, Joshua Y. Sakamaki Jun 2016

Cooperative Estimation For A Vision-Based Multiple Target Tracking System, Joshua Y. Sakamaki

Theses and Dissertations

In this thesis, the Recursive-Random Sample Consensus (R-RANSAC) algorithm is applied to a vision-based, cooperative target tracking system. Unlike previous applications, which focused on a single camera platform tracking targets in the image frame, this work uses multiple camera platforms to track targets in the inertial or world frame. The process of tracking targets in the inertial frame is commonly referred to as geolocation.In practical applications sensor biases cause the geolocated target estimates to be biased from truth. The method for cooperative estimation developed in this thesis first estimates the relative rotational and translational biases that exist between tracks from …

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Typical And Darkened Portland Cement Concrete Pavement: Temperature, Moisture, And Roughness Analyses, Tenli Waters Jun 2016

Typical And Darkened Portland Cement Concrete Pavement: Temperature, Moisture, And Roughness Analyses, Tenli Waters

Theses and Dissertations

The objectives of this research were to 1) investigate the effects of lower concrete albedo on the thermal behavior of concrete pavement by directly comparing temperatures and moisture contents of typical and darkened concrete pavements and 2) investigate changes in roughness of both typical and darkened concrete pavements as a result of changes in temperature and moisture gradients. The scope of the research included instrumentation, testing, and analysis of typical and darkened concrete pavements constructed in northern Utah.Procedures related to field testing included infrared thermography, thermocouple readings, sensor data collection, and roughness surveys. Elevation surveys and albedo measurements were also …

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Modeling And Control Of A Tailsitter With A Ducted Fan, Matthew Elliott Argyle Jun 2016

Modeling And Control Of A Tailsitter With A Ducted Fan, Matthew Elliott Argyle

Theses and Dissertations

There are two traditional aircraft categories: fixed-wing which have a long endurance and a high cruise airspeed and rotorcraft which can take-off and land vertically. The tailsitter is a type of aircraft that has the strengths of both platforms, with no additional mechanical complexity, because it takes off and lands vertically on its tail and can transition the entire aircraft horizontally into high-speed flight. In this dissertation, we develop the entire control system for a tailsitter with a ducted fan. The standard method to compute the quaternion-based attitude error does not generate ideal trajectories for a hovering tailsitter for some …

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Novel Techniques For Rapid Cardiac Perfusion Magnetic Resonance Imaging With Whole Heart Coverage, Haonan Wang Jun 2016

Novel Techniques For Rapid Cardiac Perfusion Magnetic Resonance Imaging With Whole Heart Coverage, Haonan Wang

Theses and Dissertations

Magnetic Resonance Imaging (MRI) is a non-invasive medical imaging method that is used in the diagnosis of many common diseases. Compared to other medical imaging modalities, MRI has the ability to provide high-resolution 2D and 3D images in arbitrary orientations, without the use of potentially damaging ionizing radiation. Myocardial perfusion MRI is a promising non- invasive clinical way to detect cardiac disease. It can also provide quantitative analysis for blood flow within the heart. However, MRI requires longer scan times to acquire images at comparable resolutions to some other imaging modalities. Increasing image resolution, both spatially and temporally, is very …

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Jezik: A Cognitive Translation System Employing A Single, Visible Spectrum Tracking Detector, Davor Bzik Jun 2016

Jezik: A Cognitive Translation System Employing A Single, Visible Spectrum Tracking Detector, Davor Bzik

Theses and Dissertations

A link between eye movement mechanics and the mental processing associated with text reading has been established in the past. The pausing of an eye gaze on a specific word within a sentence reflects correctness or fluency of a translated text. A cognitive translation system has been built employing a single, inexpensive web camera without the use of infrared illumination. It was shown that the system translates the text, detects rarely occurring and out-of-context words from eye gaze information, and provides solutions in real time while the user is still reading. The solutions are in form of a translation, definition …

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Thermal And Convective Loading Methods For Releasing Hydrophobic Therapeutics From Contact Lenses, Ryan Ruben Horne Jun 2016

Thermal And Convective Loading Methods For Releasing Hydrophobic Therapeutics From Contact Lenses, Ryan Ruben Horne

Theses and Dissertations

This thesis investigates the feasibility of loading silicone hydrogel (SiHy) contact lenses with two different hydrophobic therapeutics, latanoprost and DMPC (1,2-dimyristoyl-sn-glycero-3-phosphocholine), for treatment of glaucoma and hyperemia respectively. The two methods of loading were 1) thermal loading in an aqueous medium and 2) convective loading in a solution of n-propanol. Dailies Total1® lenses prepared in this manner were tested for their loading and their release into artificial tears. Continuous release over 1-4 days at therapeutic levels is achievable from thermal loading of DMPC, convective loading of DMPC, and convective loading of latanoprost. The DMPC loading processes can be naturally integrated …

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A Quantitative Approach To The Identification And Prediction Of Supply Chain Agility, David A. Sheffield Jun 2016

A Quantitative Approach To The Identification And Prediction Of Supply Chain Agility, David A. Sheffield

Theses and Dissertations

As the product-release cycle in the tech industry speeds up, there is more pressure on manufacturers to bring new products to market faster than ever. This puts a great deal of pressure on the suppliers of capital equipment used to manufacture these tech products. The supply chain agility of these suppliers is increasingly important. The purpose of this study is three-fold (1) to develop a methodology that can be used by any firm for measuring and ranking the agility of suppliers and finding the root causes of supplier agility, (2) to develop the first-ever fully quantitative measure of supply chain …

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Multi-Sensor Robust Relative Estimation Framework For Gps-Denied Multirotor Aircraft, Tim Mclain, Daniel P. Koch, Kevin M. Brink Jun 2016

Multi-Sensor Robust Relative Estimation Framework For Gps-Denied Multirotor Aircraft, Tim Mclain, Daniel P. Koch, Kevin M. Brink

Faculty Publications

An estimation framework is presented that improves the robustness of GPS-denied state estimation to changing environmental conditions by fusing updates from multiple view-based odometry algorithms. This allows the vehicle to utilize a suite of complementary exteroceptive sensors or sensing modalities. By estimating the vehicle states relative to a local coordinate frame collocated with an odometry keyframe, observability of the relative state is maintained. A description of the general framework is given, as well as the specific equations for a multiplicative extended Kalman filter with a multirotor vehicle. Experimental results are presented that demonstrate the ability of the proposed algorithm to …

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Dynamic Liquefied Natural Gas (Lng) Processing With Energy Storage Applications, Farhad Fazlollahi Jun 2016

Dynamic Liquefied Natural Gas (Lng) Processing With Energy Storage Applications, Farhad Fazlollahi

Theses and Dissertations

The cryogenic carbon capture™ (CCC) process provides energy- and cost-efficient carbon capture and can be configured to provide an energy storage system using an open-loop natural gas (NG) refrigeration system, which is called energy storing cryogenic carbon capture (CCC-ES™). This investigation focuses on the transient operation and especially on the dynamic response of this energy storage system and explores its efficiency, effectiveness, design, and operation. This investigation included four tasks.The first task explores the steady-state design of four different natural gas liquefaction processes simulated by Aspen HYSYS. These processes differ from traditional LNG process in that the CCC process vaporizes …

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Investigation Of Structural Capacity Of Geogrid-Reinforced Aggregate Base Materials In Flexible Pavements, Eric J. Sweat Jun 2016

Investigation Of Structural Capacity Of Geogrid-Reinforced Aggregate Base Materials In Flexible Pavements, Eric J. Sweat

Theses and Dissertations

The installation of geogrid as a means of extending the service life of a roadway or reducing the required base course thickness of a pavement structure has become increasingly popular. The realization of these benefits depends largely on the degree to which the geogrid reinforcement leads to an increase in the stiffness of the aggregate base course layer. The objective of this research was to investigate the structural capacity of geogrid-reinforced aggregate base materials in flexible pavements through full-scale testing. The scope involved field testing at two sites in northern Utah that each included five different geogrid-reinforced sections and five …

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Quantifying Computer Vision Model Quality Using Various Processing Techniques, Samantha Anna Ruggles Jun 2016

Quantifying Computer Vision Model Quality Using Various Processing Techniques, Samantha Anna Ruggles

Theses and Dissertations

Recently, the use of unmanned aerial vehicles (UAVs) has increased in popularity across several industries. Most notable, however, is the impact that this technology has had in research at academic institutions worldwide. As the technology for UAVs has improved, with that comes easier to operate, more accessible equipment. UAVs have been used in various types of applications and are quickly becoming a preferred method of studying and analyzing a site. Currently, the most common use of a UAV is to monitor a location of interest to a researcher that is difficult to gain access to otherwise. The UAV can be …

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Nerve Regeneration Using Lysophosphatidylcholine And Nerve Growth Factor, Ryan Lavar Wood Jun 2016

Nerve Regeneration Using Lysophosphatidylcholine And Nerve Growth Factor, Ryan Lavar Wood

Theses and Dissertations

Peripheral nerve damage affects hundreds of thousands of people every year. This study tested the effectiveness of using lysophosphatidylcholine (LPC) in combination with nerve growth factor (NGF) to increase the healing rate of damaged left sciatic nerves in female rats. The rats were randomly divided into eight groups: Sham, Right Sciatic, Crush, LPC, LPC-NGF, Crush- LPC, Crush-NGF, and Crush-LPC-NGF. The healing of the nerves was measured by monitoring gait, electrophysiological parameters (compound muscle action potential amplitudes and nerve conductance velocities) and morphological parameters (total fascicular area, total myelinated fiber counts, fiber densities, fiber diameters, and g-ratio). Gait and electrophysiological parameters …

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Design And Analysis Of Two Compliant Mechanism Designs For Use In Minimally Invasive Surgical Instruments, Jason Lon Dearden Jun 2016

Design And Analysis Of Two Compliant Mechanism Designs For Use In Minimally Invasive Surgical Instruments, Jason Lon Dearden

Theses and Dissertations

Minimally invasive surgery (MIS) has several advantages over traditional methods. Scaling MIS instruments to smaller sizes and increasing their performance will enable surgeons to offer new procedures to a wider range of patients. In this work, two compliant mechanism-based minimally invasive surgical instrument wrist or gripper mechanisms are designed and analyzed.The cylindrical cross-axis flexural pivot (CCAFP) is a single-degree-of-freedom wrist mechanism that could be combined with existing gripper mechanisms to create a multi-degree-of freedom instrument. The simplicity of the CCAFP mechanism facilitates analysis and implementation. The flexures of the CCAFP are integral with the instrument shaft, enabling accessories to be …

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