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Articles 2161 - 2190 of 4850

Full-Text Articles in Engineering

Optimization-Based Path Planning For Separation Assurance On Small Unmanned Aircraft, Matthew Duffield, Andrew Ning, Timothy Mclain Jan 2016

Optimization-Based Path Planning For Separation Assurance On Small Unmanned Aircraft, Matthew Duffield, Andrew Ning, Timothy Mclain

Faculty Publications

This paper presents a time-based path planning optimizer for separation assurance for unmanned aircraft systems (UAS). Given Automatic Dependent Surveillance-Broadcast (ADS-B) as a sensor, intruder information such as position, velocity, and identification information is available at ranges on the order of 50 nautical miles. Such long-range intruder detection facilitates path planning for separation assurance, but also poses computational challenges. The time-based path optimizer presented in this paper provides a path-planning method that takes advantage of long-range ADS-B information and addresses the associated challenges. It is capable of long-range path planning and, due to the convex formulation, is computationally efficient enough …

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Parameterized Vertical-Axis Wind Turbine Wake Model Using Cfd Vorticity Data, Andrew Ning, Eric Tingey Jan 2016

Parameterized Vertical-Axis Wind Turbine Wake Model Using Cfd Vorticity Data, Andrew Ning, Eric Tingey

Faculty Publications

In order to analyze or optimize a wind farm layout, reduced-order wake models are often used to estimate the interactions between turbines. While many such models exist for horizontal-axis wind turbines, for vertical-axis wind turbines (VAWTs) a simple parametric wake model does not exist. Using computational fluid dynamic (CFD) simulations we computed vorticity in a VAWT wake, and parameterized the data based on normalized downstream positions, tip-speed ratio, and solidity to predict a normalized wake velocity deficit. When compared to CFD, which takes about a day to run one simulation, the reduced-order model predicts the velocity deficit at any location …

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Landing Zone Determination For Autonomous Rotorcraft In Surveillance Applications, Timothy Mclain, Gary J. Ellingson, Justin Mackay Jan 2016

Landing Zone Determination For Autonomous Rotorcraft In Surveillance Applications, Timothy Mclain, Gary J. Ellingson, Justin Mackay

Faculty Publications

This paper presents an approach for finding possible landing sites for a rotorcraft from an inertially referenced point-cloud model of the environment. To identify potential landing sites that are suitably flat and level, a grid-based random sample consensus algorithm separates the terrain map into discrete areas for plane-fitting analysis. Landing sites are selected that satisfy constraints on flatness and levelness while optimizing the surveillance target’s visibility. Flight test results are presented from a small multirotor aircraft flying over a scale-model cityscape. Results from real-time landing-site experiments are presented and discussed.

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A Comparison Of Simple Global Kinetic Models For Coal Devolatilization With The Cpd Model, Andrew Richards, Thomas H. Fletcher Jan 2016

A Comparison Of Simple Global Kinetic Models For Coal Devolatilization With The Cpd Model, Andrew Richards, Thomas H. Fletcher

Faculty Publications

Simulations of coal combustors and gasifiers generally cannot incorporate the complexities of advanced pyrolysis models, and hence there is interest in evaluating simpler models over ranges of temperature and heating rate that are applicable to the furnace of interest. In this paper, six different simple model forms are compared to predictions made by the Chemical Percolation Devolatilization (CPD) model. The model forms included three modified one-step models, a simple two-step model, and two new modified two-step models. These simple model forms were compared over a wide range of heating rates (5000 to 106 K/s) at final temperatures up to …

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Independent Effects Of Surface And Gas Temperature On Coal Fly Ash Deposition In Gas Turbines At Temperatures Up To 1400 C, Robert Laycock, Thomas H. Fletcher Jan 2016

Independent Effects Of Surface And Gas Temperature On Coal Fly Ash Deposition In Gas Turbines At Temperatures Up To 1400 C, Robert Laycock, Thomas H. Fletcher

Faculty Publications

Deposition of coal fly ash in gas turbines has been studied to support the concept of integrated gasification combined cycle (IGCC). Although particle filters are used in IGCC, small amounts of ash particles less than 5 microns in diameter enter the gas turbine. Previous deposition experiments in the literature have been conducted at temperatures up to about 1288 C. However, few tests have been conducted that reveal the independent effects of gas and surface temperature, and most have been conducted at gas temperatures lower than 1400 C. The independent effects of gas and surface temperature on particle deposition in a …

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Optical Approach To Resin Formulation For 3d Printed Microfluidics, Hua Gong, Michael Beauchamp, Steven Perry, Adam T. Woolley, Gregory P. Nordin Dec 2015

Optical Approach To Resin Formulation For 3d Printed Microfluidics, Hua Gong, Michael Beauchamp, Steven Perry, Adam T. Woolley, Gregory P. Nordin

Faculty Publications

Microfluidics imposes different requirements on 3D printing compared to many applications because the critical features for microfluidics consist of internal microvoids. Resins for general 3D printing applications, however, are not necessarily formulated to meet the requirements of microfluidics and minimize the size of fabricated voids. In this paper we use an optical approach to guide custom formulation of resins to minimize the cross sectional size of fabricated flow channels as exemplars of such voids. We focus on stereolithgraphy (SL) 3D printing with Digital Light Processing (DLP) based on a micromirror array and use a commercially available 3D printer. We develop …

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Use Of Personality Profile Assessments In The Construction Industry, Brian Richard Childs Dec 2015

Use Of Personality Profile Assessments In The Construction Industry, Brian Richard Childs

Theses and Dissertations

Various industries are using personality profile assessments as tools to help reduce employee turnover. Employee turnover is a continuing challenge in the construction industry that has negative effects on construction companies. Research found that it was difficult to know if companies in the construction industry are using personality profile assessments as a tool to help reduce employee turnover. After understanding that other industries were using personality profile assessments in their hiring, promoting, team building and leadership development to reduce turnover, it was desired to understand if the construction industry was doing the same. This research performed a survey among the …

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A Pilot Study To Determine The Performance Of Tension Lap Splices In Reinforced Masonry Made With Light-Weight Grout, Brandon Richard Corbett Dec 2015

A Pilot Study To Determine The Performance Of Tension Lap Splices In Reinforced Masonry Made With Light-Weight Grout, Brandon Richard Corbett

Theses and Dissertations

The use of light-weight building materials in modern construction has resulted in efficient designs and considerable cost savings by reducing structural weight and supporting sections. This has only been possible because of many years of research to better understand the properties of the light-weight material, and its structural behaviors. However, light-weight grout is a relatively new building material in reinforced masonry construction and little is known about its structural properties. The main objective of this study was to determine if the use of light-weight grout would impact the performance of reinforcing steel, specifically development length, in masonry construction.The research included …

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Rubidium Packaging For On-Chip Spectroscopy, Cameron Louis Hill Dec 2015

Rubidium Packaging For On-Chip Spectroscopy, Cameron Louis Hill

Theses and Dissertations

This thesis presents rubidium packaging methods for integration using anti-resonant reflecting optical waveguides (ARROWs) on a planar chip. The atomic vapor ARROW confines light through rubidium vapor, increases the light-vapor interaction length, decreases the size of the atomic cell to chip scales, and opens up possibilities for waveguide systems on chips for additional optoelectronic devices. Rubidium vapor packaging for long-life times are essential for realizing feasibly useful devices. Considerations of outgassing, leaking and chemical compatibilities of materials in rubidium vapor cells lead to an all-metal design. The effect of these characteristics on the rubidium D2 line spectra is considered.

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Laboratory Resilient Modulus Measurements Of Aggregate Base Materials In Utah, Kirk David Jackson Dec 2015

Laboratory Resilient Modulus Measurements Of Aggregate Base Materials In Utah, Kirk David Jackson

Theses and Dissertations

The Utah Department of Transportation (UDOT) has fully implemented the Mechanistic-Empirical Pavement Design Guide for pavement design but has been using primarily level-three design inputs obtained from correlations to aggregate base materials developed at the national level. UDOT was interested in investigating correlations between laboratory measurements of resilient modulus, California bearing ratio (CBR), and other material properties specific to base materials commonly used in Utah; therefore, a statewide testing program was needed. The objectives of this research were to 1) determine the resilient modulus of several representative aggregate base materials in Utah and 2) investigate correlations between laboratory measurements of …

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Springback Force Considerations In Compliant Haptic Interfaces, Dallin R. Swiss Dec 2015

Springback Force Considerations In Compliant Haptic Interfaces, Dallin R. Swiss

Theses and Dissertations

This thesis investigates the potential benefits and challenges of using compliant mechanisms in the design of haptic interfaces. The benefits and challenges are presented with an emphasis on their inherent springback behavior and an active compensation approach. Design criteria for compliant mechanism joint candidates are reviewed and several joints are surveyed. Quantitative calculations of axial stiffness and maximum stress for five candidates are presented. Generalized analytical models of springback force and compensation torque are created to simulate the implementation of each joint candidate in a two degree-of-freedom planar pantograph. We use these models in the development and discussion of an …

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Elucidating The Mechanisms Of Rate-Dependent Deformation At Ambient Temperatures In A Model Metallic Glass, Matthew Bradley Harris Dec 2015

Elucidating The Mechanisms Of Rate-Dependent Deformation At Ambient Temperatures In A Model Metallic Glass, Matthew Bradley Harris

Theses and Dissertations

In this work, the Shear Transformation Zone (STZ) dynamics model is adapted to capture the transitions between different regimes of flow serration in the deformation map of metallic glass. This was accomplished by scaling the STZ volume with a log-linear fit to the strain rate, and also adjusting the activation energy of an STZ with a log-linear fit to maintain constant yield strength at differing strain rates. Twelve simulations are run at each of six different strain rates ranging from 10-5 to 100 s-1, and statistics are collected on simulation behavior and shear band nucleation and …

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Effects Of Various Mobility Aids On Lower-Extremity Muscle Activity, Michael Ryan Sanders Dec 2015

Effects Of Various Mobility Aids On Lower-Extremity Muscle Activity, Michael Ryan Sanders

Theses and Dissertations

Millions of people each year spend some portion of their time using mobility aids to facilitate periods of non-weight bearing ambulation. The use of these devices changes the loading conditions of the lower extremities, which may result in skeletal muscle adaptations. The purpose of this work was to evaluate the effects of 3 types of mobility aids on lower-extremity muscle activity. Evaluation was based on 1) measured muscle activation signals using electromyography (EMG), and 2) measured joint kinematics and ground reaction forces, which were used to predict muscle forces. 16 healthy subjects (7 female, 9 male), ages 18-27 participated in …

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An Automated Tool For High Resolution Visualization Applied To Transient Watershed Models, Noah Robert Taylor Dec 2015

An Automated Tool For High Resolution Visualization Applied To Transient Watershed Models, Noah Robert Taylor

Theses and Dissertations

Numeric hydrologic models can aid in water resource management by providing predictive simulations of water behavior. As computers become more advanced, the models developed also become more complex using more data to represent larger areas for forecasting hydrologic behavior. Unfortunately, as the simulations use more data, the output often becomes difficult to manage and share without investing time and effort into setting up server environments or decreasing the quality of the output to compensate for an efficient and effective user experience. A proposed solution to facilitate the accessibility of massive hydrologic model output is through the web-based visualization tool developed …

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Configuration Scrubbing Architectures For High-Reliability Fpga Systems, Aaron Gerald Stoddard Dec 2015

Configuration Scrubbing Architectures For High-Reliability Fpga Systems, Aaron Gerald Stoddard

Theses and Dissertations

Field Programmable Gate Arrays (FPGAs) are being used more frequently in space applications because of their reconfigurability and intensive processing capabilities. FPGAs in environments like space are susceptible to ionizing radiation which can cause Single Event Upsets (SEUs) in the FPGA's configuration memory. These upsets may cause the programmed user design on the FPGA to deviate from its normal behavior. Space missions cannot afford to allow important data processing applications to become corrupted due to these radiation upsets.Configuration scrubbing is an upset mitigation technique that detects and corrects upsets in an FPGA's configuration memory. Configuration scrubbing periodically monitors an FPGA's …

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Evaluating Long-Term Land Cover Changes For Malheur Lake, Oregon Using Envi And Arcgis, Ryan Joseph Woods Dec 2015

Evaluating Long-Term Land Cover Changes For Malheur Lake, Oregon Using Envi And Arcgis, Ryan Joseph Woods

Theses and Dissertations

Land cover change over time can be a useful indicator of variations in a watershed, such as the patterns of drought in an area. I present a case study using remotely sensed images from Landsat satellites for over a 30-year period to generate classifications representing land cover categories, which I use to quantify land cover change in the watershed areas that contribute to Malheur, Mud, and Harney Lakes. I selected images, about every 4 to 6 years from late June to late July, in an attempt to capture the peak vegetation growth and to avoid cloud cover. Complete coverage of …

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Shaking Table Testing To Evaluate Effectiveness Of Prefabricated Vertical Drains For Liquefaction Mitigation, Caleb Robert Oakes Dec 2015

Shaking Table Testing To Evaluate Effectiveness Of Prefabricated Vertical Drains For Liquefaction Mitigation, Caleb Robert Oakes

Theses and Dissertations

This study was designed to evaluate the ability of vertical drains to prevent liquefaction and limit associated settlement. Drain performance was investigated using full-scale tests with vertical drains in liquefiable sand using a laminar shear box with acceleration time histories applied at the base. Performance of the sand box with drains in these tests was compared with performance of the sane box without drains in previous tests. The test data was also used to create case histories which can be used for further research and calibration of computer models. Although some investigations regarding vertical drains have been performed with centrifuge …

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Numerical Analysis Of Passive Force On Skewed Bridge Abutments, Zifan Guo Dec 2015

Numerical Analysis Of Passive Force On Skewed Bridge Abutments, Zifan Guo

Theses and Dissertations

Accounting for seismic forces and thermal expansion in bridge design requires an accurate passive force-deflection relationship for the abutment wall. Current design codes make no allowance for skew effects on passive force; however, large scale field tests indicate that there is a substantial reduction in peak passive force as skew angle increases. A reduction in passive force also reduces the transverse shear resistance on the abutment. The purpose of this study is to validate three-dimensional model using PLAXIS 3D, against large scale test results performed at Brigham Young University and to develop a set of calibrated finite element models. The …

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Galvanic Corrosion Of Magnesium Coupled To Steel At High Cathode-To-Anode Area Ratios, Dila Ram Banjade Dec 2015

Galvanic Corrosion Of Magnesium Coupled To Steel At High Cathode-To-Anode Area Ratios, Dila Ram Banjade

Theses and Dissertations

In this study, the impact of galvanic coupling of magnesium to steel on the corrosion rate, surface morphology, and surface film formation was investigated. In particular, the role of self-corrosion was quantified as previous studies showed discrepancies between model predictions and experimental results that were likely due to significant self-corrosion. This experimental study examined the corrosion of Mg coupled to steel in 5 wt% NaCl at cathode-to-anode area ratios that ranged from 5 to 27. Results showed that self-corrosion was significant and accounted for, on average, one-third of total corrosion. Moreover, self-corrosion varied with time and cathode size, and was …

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Enhanced-Resolution Processing And Applications Of The Ascat Scatterometer, Richard D. Lindsley Dec 2015

Enhanced-Resolution Processing And Applications Of The Ascat Scatterometer, Richard D. Lindsley

Theses and Dissertations

The ASCAT scatterometer measures the Earth surface microwave radar backscatter in order to estimate the near-surface winds over the oceans. While the spatial resolution of the conventional applications is sufficient for many purposes, other geoscience applications benefit from an improved spatial resolution. Specialized algorithms may be applied to the scatterometer data in order to reconstruct the radar backscatter on a high-resolution grid. Image reconstruction requires the spatial response function (SRF) of each measurement, which is not reported with the measurement data. To address this need, I precisely model the SRF incorporating (1) the antenna beam response, (2) the processing performed …

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Characterizing The Effects Of Capillary Flow During Liquid Composite Molding, Michael Ray Morgan Dec 2015

Characterizing The Effects Of Capillary Flow During Liquid Composite Molding, Michael Ray Morgan

Theses and Dissertations

As the aerospace industry continues to incorporate composites into its aircraft, there will be a need for alternative solutions to the current autoclaving process. Liquid composite molding (LCM) has proven to be a promising alternative, producing parts at faster rates and reduced costs while retaining aerospace grade quality. The most important factor of LCM is controlling the resin flow throughout the fiber reinforcement during infusion, as incomplete filling of fibers is a major quality issue as it results in dry spots or voids. Void formation occurs at the resin flow front due to competition between viscous forces and capillary pressure. …

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Stochastic Simulation Of Lagrangian Particle Transport In Turbulent Flows, Guangyuan Sun Dec 2015

Stochastic Simulation Of Lagrangian Particle Transport In Turbulent Flows, Guangyuan Sun

Theses and Dissertations

This dissertation presents the development and validation of the One Dimensional Turbulence (ODT) multiphase model in the Lagrangian reference frame. ODT is a stochastic model that captures the full range of length and time scales and provides statistical information on fine-scale turbulent-particle mixing and transport at low computational cost. The flow evolution is governed by a deterministic solution of the viscous processes and a stochastic representation of advection through stochastic domain mapping processes. The three algorithms for Lagrangian particle transport are presented within the context of the ODT approach. The Type-I and -C models consider the particle-eddy interaction as instantaneous …

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Overview Of Estimation Methods For Industrial Dynamic Systems, John Hedengren, Ammon Eaton Nov 2015

Overview Of Estimation Methods For Industrial Dynamic Systems, John Hedengren, Ammon Eaton

Faculty Publications

Measurement technology is advancing in the oil and gas industry. Factors such as wireless transmitters, reduced cost of measurement technology, and increased regulations that require active monitoring tend to increase the number of available measurements. There is a clear opportunity to distill the recent flood of measurements into relevant and actionable information. Common methods to do this include a filtered bias update, implicit dynamic feedback, Kalman filtering, and moving horizon estimation. The purpose of these techniques is to validate measurements and align imperfect mathematical models to the actual process. Additionally, they can determine a best-estimate of the current state of …

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Aerodynamic Improvement Of The Byu Supermileage Vehicle, Sayan Dobronsky Nov 2015

Aerodynamic Improvement Of The Byu Supermileage Vehicle, Sayan Dobronsky

Theses and Dissertations

The purpose of this thesis work was to design a new shape for the BYU Supermileage vehicle in order to improve its fuel efficiency. Computational Fluid Dynamics (CFD) was used to obtain the coefficient of drag (CD) and drag area of the current baseline vehicle at a Reynolds number of 1.6x10^6 and 8.7x10^5. Then a new shape was developed using mesh morphing software. The new shape was imported into the CFD program and the drag figures and airflow plots from the modified design were compared with the baseline vehicle. Scale models of the vehicles were also printed using a 3D …

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Integrating Process Mining With Discrete-Event Simulation Modeling, Siyao Liu Nov 2015

Integrating Process Mining With Discrete-Event Simulation Modeling, Siyao Liu

Theses and Dissertations

Discrete-event simulation (DES) is an invaluable tool which organizations can use to help better understand, diagnose, and optimize their operational processes. Studies have shown that for the typical DES exercise, the greatest amount of time is spent on developing an accurate model of the process that is to be studied. Process mining, a similar field of study, focuses on using historical data stored in software databases to accurate recreate and analyze business processes. Utilizing process mining techniques to help rapidly develop DES models can drastically reduce the amount of time spent building simulation models, which ultimately will enable organizations to …

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Deriving System Vulnerabilities Using Log Analytics, Matthew Somers Higbee Nov 2015

Deriving System Vulnerabilities Using Log Analytics, Matthew Somers Higbee

Theses and Dissertations

System Administrators use many of the same tactics that are implemented by hackers to validate the security of their systems, such as port scanning and vulnerability scanning. Port scanning is slow, and can be highly inaccurate. After a scan is complete, the results of the scan must be cross checked with a vulnerability database to discover if any vulnerabilities are present. While these techniques are useful, they have severe limitations. System Administrators have full access to all of their machines. They should not have to rely exclusively on port scanning them from the outside of their machines to check for …

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High-Efficiency Passive And Active Phased Arrays And Array Feeds For Satellite Communications, Zhenchao Yang Nov 2015

High-Efficiency Passive And Active Phased Arrays And Array Feeds For Satellite Communications, Zhenchao Yang

Theses and Dissertations

Satellite communication (Satcom) services are used worldwide for voice, data, and video links due to various appealing features. Parabolic reflector antennas are typically used to serve a cost effective scheme for commercial applications. However, mount degradation, roof sag, and orbital decay motivate the need for beam steering. Limited scan range beam steering opens a third option for electronic beam steering with lower cost than full aperture phased arrays and higher tracking speed and accuracy than mechanical-only steering.Multiple high efficiency passive patch array feeds were designed, fabricated, and measured, including a 2x2 MSA array, a stacked shorted annular patch antenna, and …

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A Compact Phased Array Radar For Uas Sense And Avoid, Jonathan Cullinan Spencer Nov 2015

A Compact Phased Array Radar For Uas Sense And Avoid, Jonathan Cullinan Spencer

Theses and Dissertations

As small unmanned aerial systems (UAS) are introduced into the national airspace, measures must be introduced to ensure that they do not interfere with manned aviation and other UAS. Radar provides an attractive solution because of its inherent range accuracy and because it works in diverse weather and lighting conditions. Traditional radar systems, however, are large and high power and do not meet the size, weight and power (SWaP) constraints imposed by UAS, and fully integrated automotive solution do not provide the necessary range. This thesis proposes a compact radar system that meets both the SWaP and range requirements for …

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Prediction And Validation Of External Cooling Loop Cryogenic Carbon Capture (Ccc-Ecl) For Full-Scale Coal-Fired Power Plant Retrofit, Mark J. Jensen, Christopher S. Russell, David Bergerson, Christopher D. Hoeger, David J. Frankman, Christopher S. Bence, Larry Lin Baxter Nov 2015

Prediction And Validation Of External Cooling Loop Cryogenic Carbon Capture (Ccc-Ecl) For Full-Scale Coal-Fired Power Plant Retrofit, Mark J. Jensen, Christopher S. Russell, David Bergerson, Christopher D. Hoeger, David J. Frankman, Christopher S. Bence, Larry Lin Baxter

Faculty Publications

Bench-scale experiments and Aspen Plus (TM) simulations document full-scale, steady-state performance of the external cooling loop cryogenic carbon capture (CCC-ECL) process for a 550 MWe coal-fired power plant. The baseline CCC-ECL process achieves 90% CO2 capture, and has the potential to capture 99+ % of CO2, SO2, PM, NO2, Hg, and most other noxious species. The CCC-ECL process cools power plant flue gas to 175 K, at which point solid CO2 particles desublimate as the flue gas further cools to 154K. Desublimating flue gas cools in a staged column in direct contact with a cryogenic liquid and produces a CO2-lean …

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Design And Manufacture Of Mesoscale Robot-Actuated Surgical Instruments, Clayton L. Grames Nov 2015

Design And Manufacture Of Mesoscale Robot-Actuated Surgical Instruments, Clayton L. Grames

Theses and Dissertations

Minimally Invasive Surgery (MIS) is a growing field including both laparoscopic androbotic operations. Surgeons and engineers are making continual efforts to reduce the negative effects of procedures on patients. Reducing the size of the surgical instruments is one effective method pursued in this effort. When the instruments approach 3 mm in diameter, they reach a threshold where the entry incisions can be small enough that no scar is left on the patient. Laparoscopic instruments on this scale exist but typically lack wrist articulation and only have 1 degree of freedom (DoF). Alternatively, robotic surgical instruments can achieve high levels of …

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