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Articles 2131 - 2160 of 2584

Full-Text Articles in Engineering

A Genetic Approach To Voltage Collapse Mitigation, Dwarakesh Nallan Chakravartula Dec 2009

A Genetic Approach To Voltage Collapse Mitigation, Dwarakesh Nallan Chakravartula

All Theses

The objective of this thesis is to provide an efficient and accurate corrective solution to a system that is on verge of voltage collapse. This thesis describes, in detail, the development of an optimization scheme that aims to alleviate power system instability and voltage collapse condition based on the principles of an evolutionary approach called Genetic Algorithm. The state of a system is determined using a voltage stability identifier termed Collapse Proximity Index (CPI) and the critical loading condition is identified. Applying principles of Genetic Algorithm, the critical system is brought back to a stable operating region. The sequential procedure …

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Identifying The Optimum Process Parameters Of Precision Glass Molding For Aspherical Lenses, Waqas Iqbal Dec 2009

Identifying The Optimum Process Parameters Of Precision Glass Molding For Aspherical Lenses, Waqas Iqbal

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The purpose of this research is to determine the optimum process parameters for the Precision Glass Molding (PGM) Process using Manufacturing Design, Design of Experiments and Metrology (for measuring the geometry of lenses). First, a custom machine is designed and manufactured which can carry out Precision Glass Lens Molding Experiments. This machine is then modified to improve temperature, position and force control. A literature review is performed to obtain data for process parameters that have been used in previous PGM studies. The collected data is then used in Design of Experiments to create twenty seven experiments that determine the optimum …

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Identifying And Comparing Key Process Attributes For Sustainable Building Delivery In India And The U.S., Prashanth Palanisamy Dec 2009

Identifying And Comparing Key Process Attributes For Sustainable Building Delivery In India And The U.S., Prashanth Palanisamy

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India is a rapidly developing nation with the associated brisk pace of construction. More sustainable building practices for construction in India would have social, environmental, and economic benefits. However, the key process attributes for successfully planning, designing, and constructing sustainable buildings in India are largely undefined. Other projects in India would benefit from a rigorous identification of these key process attributes which could help leapfrogging the sustainable building delivery in India to the best available practices.
Sustainable buildings require different delivery processes than traditional buildings; this can lead to process wastes due to unfamiliarity or incompatibility of the processes. These …

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The Design Of An Ic Half Precision Floating Point Arithmetic Logic Unit, Balaji Kannan Dec 2009

The Design Of An Ic Half Precision Floating Point Arithmetic Logic Unit, Balaji Kannan

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A 16 bit floating point (FP) Arithmetic Logic Unit (ALU) was designed and implemented in 0.35µm CMOS technology. Typical uses of the 16 bit FP ALU include graphics processors and embedded multimedia applications.
The ALU of the modern microprocessors use a fused multiply add (FMA) design technique. An advantage of the FMA is to remove the need for a comparator which is required for a normal FP adder. The FMA consists of a multiplier, shifters, adders and rounding circuit. A fast multiplier based on the Wallace tree configuration was designed. The number of partial products was greatly reduced by the …

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2-D And 3-D Assessment Of Cambered And Symmetric Airfoils: A Cfd Study, Tuncay Kamas Dec 2009

2-D And 3-D Assessment Of Cambered And Symmetric Airfoils: A Cfd Study, Tuncay Kamas

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A two dimensional and three dimensional computational study has been carried out respectively regarding aerodynamic forces affecting a symmetric airfoil, NACA0015 and a cambered airfoil, NACA2414. The negative lift (down force) and drag forces were predicted through the simulation of airflows over inverted rear-wings in different configurations namely; varying incidences i.e. angles of attack of the airfoils, two dimensional cross section of the inverted rear wings to be mounted on back of a car, and varying speeds of initial airflow.
The downforce increases as the angle of attack increases however, if an inverted rear wing is fixed on a car …

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Neomycin Enhances Glutaraldehyde Crosslinking And Glycosaminoglycan Stability In Bioprosthetic Heart Valves, Vincent Friebe Dec 2009

Neomycin Enhances Glutaraldehyde Crosslinking And Glycosaminoglycan Stability In Bioprosthetic Heart Valves, Vincent Friebe

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The native heart valve will open and close an astonishing 3 billion times in the average lifetime, implicating immense biomechanical ramifications that necessitate near-flawless structure and functional behavior. Deviations from this idyllic function as a result of heart valve disease (HVD) affect millions of individuals worldwide and result in over 275,000 heart valve replacements worldwide every year. Glutaraldehyde (GLUT) cross-linked porcine aortic heart valves, a common type of bioprosthetic heart valve (BHV), are used frequently in these valve replacement surgeries. The native valve leaflets entail a tri-composite design of type I collagen, elastin and glycosaminoglycans (GAGs), each of which are …

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Principal Component Thermography For Steady Thermal Perturbation Scenarios, Rohit Parvataneni Dec 2009

Principal Component Thermography For Steady Thermal Perturbation Scenarios, Rohit Parvataneni

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The work focuses on the qualitative enhancement of Thermographic Inspection data using Principal Component Analysis technique. A new processing tool named Economical Singular Value Decomposition (SVD) is proposed for analyzing the infrared image sequences acquired from the test specimen.
Experiments are carried out on test sample using thermal excitation modalities such as flash, halogen and induction to create temperature variations. The infrared (IR) image sequence containing the information about the sample is captured using IR cameras. The acquired IR image sequences are processed using the proposed Economical SVD which projects the matrix of raw pixel values of image sequence into …

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Experimental Characterization Of Stress Relaxation In Glass, Hemanth Kadali Dec 2009

Experimental Characterization Of Stress Relaxation In Glass, Hemanth Kadali

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Glass viscoelasticity has gained importance in recent years as glass lens molding appeared as a valuable alternative to the traditional grinding and polishing process for manufacturing glass lenses. In the precision lens molding process, knowledge of viscoelastic properties of glass in the transition region, which affect the stress relaxation behavior, is required to precisely predict the final size and shape of molded lenses. The purpose of this study is to establish a step-by-step procedure for characterizing the viscoelastic behavior of glass in the glass transition region using a finite term Prony series of a Generalized Maxwell model. This study focuses …

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Interactive Perception For Cluttered Environments, Robert Willimon Dec 2009

Interactive Perception For Cluttered Environments, Robert Willimon

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Robotics research tends to focus upon either non-contact sensing or machine manipulation, but not both. This paper explores the benefits of combining the two by addressing the problem of extracting and classifying unknown objects within a cluttered environment, such as found in recycling and service robot applications. In the proposed approach, a pile of objects lies on a flat background, and the goal of the robot is to sift through the pile and classify each object so that it can be studied further. One object should be removed at a time with minimal disturbance to the other objects. We propose …

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Comparing Problem-Based Learning And Lecture As Methods To Teach Whole-Systems Design To Engineering Students, Michael Dukes Dec 2009

Comparing Problem-Based Learning And Lecture As Methods To Teach Whole-Systems Design To Engineering Students, Michael Dukes

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The objective of this research is to compare problem-based learning and lecture as methods to teach whole-systems design to engineering students. A case study, Appendix A, exemplifying successful whole-systems design was developed and written by the author in partnership with the Rocky Mountain Institute. Concepts to be tested were then determined, and a questionnaire was developed to test students' preconceptions. A control group of students was taught using traditional lecture methods, and a sample group of students was taught using problem-based learning methods. After several weeks, the students were given the same questionnaire as prior to the instruction, and the …

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Charging Kinetics Of Electric Double Layer Capacitors, Clint Cagle Dec 2009

Charging Kinetics Of Electric Double Layer Capacitors, Clint Cagle

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A recent increase in the popularity of EDLCs and AC-EOF has necessitated a deeper understanding of the structure and charging kinetics of electrical double layers (EDLs) at electrode-electrolyte interfaces. Here, the charging kinetics of EDLs in nanoscale EDLCs is studied by a circuit model, a Poisson-Nernst-Planck (PNP) mo del, and molecular dynamics (MD) simulations. The results of the MD simulations demonstrate a linear charging behavior of EDLs near planar electrodes for both aqueous and organic electrolytes at charging below 90% and time larger than tens of picoseconds. Additionally, we will show that the circuit and PNP models are capable of …

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Investigation Of The Thermoelectric Behavior And Structure Formation Of (Pbte/Agsbte2)-Silver Chalcogenide Mixtures, Yisha Wang Dec 2009

Investigation Of The Thermoelectric Behavior And Structure Formation Of (Pbte/Agsbte2)-Silver Chalcogenide Mixtures, Yisha Wang

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Sustainable energy research is currently on the forefront of scientific exploration and energy conservation and the development of new energy production techniques are both crucial for our long lasting stable future. Accordingly, thermoelectric materials will be a significant energy conservation and production source. The state-of -the-art thermoelectric materials can be used to collect the wasted heat and converted to power, which is the future for the green power generation.
PbTe is considered a state-of-the-art thermoelectric material, which has been extensively studied. It forms in the NaCl structure and it is a semiconductor with a room temperature gap value of 0.29 …

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Filtering Noise Caused By Sensor Selection For An Ultra-Wide Band Position Tracking System, Danyan Ganjali Dec 2009

Filtering Noise Caused By Sensor Selection For An Ultra-Wide Band Position Tracking System, Danyan Ganjali

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A filter designed to be optimal for alternating multi-sensor tracking systems is presented. This filter can be used on ultra-wide band position tracking systems such as the Ubisense system. In this thesis, a comprehensive evaluation of the accuracy of the Ubisense tracking system in a multi-room building is given. Then the multi-modality of the noise distribution of such a system is shown. A multi-sensor tracking system is then simulated and a Kalman filter is used to filter the measurements. It is shown that the Kalman filter is not optimal for such a system and the need for a filter that …

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Design And Analysis Of Alternating Spoke Pair Concepts For A Non-Pneumatic Tire With Reduced Vibration At High Speed Rolling, Shashank Bezgam Dec 2009

Design And Analysis Of Alternating Spoke Pair Concepts For A Non-Pneumatic Tire With Reduced Vibration At High Speed Rolling, Shashank Bezgam

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Recently, Michelin has invented an innovative non-pneumatic tire which has potential for improved handling, grip, comfort, and less rolling resistance when compared to a traditional pneumatic tire. The non-pneumatic wheel is manufactured from a molding process with integrated shear ring and collapsible spokes designed to provide optimal uniform ground contact patch with low rolling resistance. The shear band is constructed from a polyurethane material with imbedded inextensible reinforcements. During high speed rolling in initial testing, the original prototype showed high noise levels at frequencies above 100 Hz. A possible source of noise could be due to vibration initiated from the …

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Robust Parameter Design And Finite Element Analysis For A Non-Pneumatic Tire With Low Vibration, Amarnath Proddaturi Dec 2009

Robust Parameter Design And Finite Element Analysis For A Non-Pneumatic Tire With Low Vibration, Amarnath Proddaturi

All Theses

During rolling of a non-pneumatic tire, vibration may be produced by the interaction of collapsible spokes with a shear deformable ring as they enter the contact region, buckle and then snap back into a state of tension. Other potential sources of vibration include the interaction of tire tread with the ground and ring vibration. In the present work, a systematic study of the effects of key geometric design parameters is presented using Taguchi's Robust Parameter Design Method and Orthogonal Arrays.
In the present work, a 2D planar finite element model with geometric non-linearity and explicit time-stepping is used to simulate …

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Vehicle-Infrastructure Integration (Vii) Enabled Plug-In Hybrid Electric Vehicles (Phevs) For Traffic And Energy Management, Xueying Kang Dec 2009

Vehicle-Infrastructure Integration (Vii) Enabled Plug-In Hybrid Electric Vehicles (Phevs) For Traffic And Energy Management, Xueying Kang

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Vehicle Infrastructure Integration (VII) program (also known as IntelliDrive) has proven the potential to improve transportation conditions by enabling the communication between vehicles and infrastructure, which provides a wide range of applications in transportation safety and mobility. Plug-in hybrid electric vehicles (PHEVs) that utilize both electrical and gasoline energy are a commercially viable technology with potential to contribute to both sustainable development and environmental conservation through increased fuel economy and reduced emissions. Considering positive potentials of PHEVs and VII in ITS, a framework that integrates PHEVs with VII technology was created in this research utilizing vehicle-to-vehicle and vehicle-to-infrastructure communications for …

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Monitoring Co Concentration In Fuel Cells Using Microcantilever Sensors, Tugba Demir Dec 2009

Monitoring Co Concentration In Fuel Cells Using Microcantilever Sensors, Tugba Demir

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Estimating the concentration of gases including carbon monoxide (CO) in the hydrogen fuel exiting the reformer and entering the fuel cell is imperative. A high concentration of CO can cause fuel-cell catalyst poisoning, which permanently destroys the cell. Current practices call for utilizing expensive and bulky spectral analyzers to achieve this task. In addition to their high cost, these methodologies, undoubtedly, hinder the portability and self-containment of the cell. To overcome these problems and achieve the desired objectives of a portable, self-contained, and real-time measurement module, this thesis presents and experimentally investigates a new enabling technology based on utilizing an …

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Relationships Between Lane Change Performance And Open-Loop Handling Metrics, Robert Powell Dec 2009

Relationships Between Lane Change Performance And Open-Loop Handling Metrics, Robert Powell

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This work deals with the question of relating open-loop handling metrics to driver-in-the-loop performance (closed-loop). The goal is to allow manufacturers to reduce cost and time associated with vehicle handling development. A vehicle model was built in the CarSim environment using kinematics and compliance, geometrical, and flat track tire data. This model was then compared and validated to testing done at Michelin's Laurens Proving Grounds using open-loop handling metrics. The open-loop tests conducted for model validation were an understeer test and swept sine or random steer test. Four commonly used handling metrics (steady state yaw rate gain, yaw rate damping …

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Friction Stir Welding Process And Material Microstructure Evolution Modeling In 2000 And 5000 Series Of Aluminum Alloys, Harshavardhan Yalavarthy Dec 2009

Friction Stir Welding Process And Material Microstructure Evolution Modeling In 2000 And 5000 Series Of Aluminum Alloys, Harshavardhan Yalavarthy

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Interactions between the rotating and advancing pin-shaped tool (terminated at one end with a circular-cylindrical shoulder) with the clamped welding-plates and the associated material and heat transport during a Friction Stir Welding (FSW) process are studied computationally using a fully-coupled thermo-mechanical finite-element analysis. To surmount potential numerical problems associated with extensive mesh distortions/entanglement, an Arbitrary Lagrangian Eulerian (ALE) formulation was used which enabled adaptive re-meshing (to ensure the continuing presence of a high-quality mesh) while allowing full tracking of the material free surfaces. To demonstrate the utility of the present computational approach, the analysis is applied to the cases of …

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Evaluation Of An Online Intelligent Transportation System (Its) Asset Management System, Tahera Anjuman Dec 2009

Evaluation Of An Online Intelligent Transportation System (Its) Asset Management System, Tahera Anjuman

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Intelligent Transportation System (ITS) enhances the performance of modern transportation systems by improving the reliability of travel times and reducing the risk of collisions and injuries. Recently, many public agencies have expressed a need for an ITS asset management system that will effectively and efficiently meet their requirements of managing associated resources, which often includes technologically sophisticated devices, computer hardware and software, and communications infrastructure. To address this need, the author evaluated different asset management systems for their potential efficacy to support public agencies requirements for an ITS asset management system. These requirements were identified through a nationwide survey of …

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Straight Line Braking Performance Of A Road Vehicle With Non Linear Tire Stiffness Formulation, Anup Khekare Dec 2009

Straight Line Braking Performance Of A Road Vehicle With Non Linear Tire Stiffness Formulation, Anup Khekare

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The capability of a road vehicle equipped with an Anti-Lock Braking System (ABS) to come to a safe stop depends on factors such as dynamic force between tire and road, surface adhesion coefficient, and the vertical profile of the road. When in panic, a driver's reaction is to step hard on the brakes to make the vehicle stop as soon as possible. Although the use of modern technologies such as ABS and Electronic Stability Control (ESC) have reduced the number of accidents significantly, any further improvement in stopping distance would only complement these technologies.
Michelin has undertaken the development of …

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Biological Treatment To Remove Color And Toxicity Of Effluent From The Manufacturing Of Navipol Yellow Gr, Larry French Dec 2009

Biological Treatment To Remove Color And Toxicity Of Effluent From The Manufacturing Of Navipol Yellow Gr, Larry French

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Navipol Yellow GR is an organic solvent azo dye manufactured by Sunbelt Corp. in Rock Hill, SC. The effluent generated from the manufacturing of this dye is highly colored, toxic, and contains trace solvents consisting of mixed xylene isomers and ethyl benzene. Traditional wastewater treatment systems are unable to remove the color and toxicity from the effluent. This study investigated using a sequential anaerobic / aerobic treatment system to decrease color and toxicity of the dye effluent. The anaerobic phase used bacteria cultures of Pseudomonas aeruginosa, Bacillus subtilis, Enterococcus faecalis, or Enterobacter aerogenes to decrease the color of the dye. …

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Mechanical And Chemical Characterization Of Biological Composite Structures, Bonnie Zimmerman Dec 2009

Mechanical And Chemical Characterization Of Biological Composite Structures, Bonnie Zimmerman

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A better understanding of the bioresponse of naturally occurring systems will help
to optimize the engineering of synthetic biomaterials. The aim of this thesis was to
characterize the mechanical and chemical behavior of two distinct biological composite
systems, human teeth and wool fibers. These mechanical and chemical properties were
also studied as a function of natural structure and environmental conditions.
Human teeth are composite systems consisting primarily of hydroxylapatite and
protein. This project investigated how the use of clinical dental treatments and
procedures, such as whitening and etching, affects mechanical properties. Analysis of
nanoindentation with the Oliver-Pharr model provided elastic …

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Efficient Analysis Of Loaded Cylindrical Monopole Antennas, Adam Schreiber Dec 2009

Efficient Analysis Of Loaded Cylindrical Monopole Antennas, Adam Schreiber

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In this dissertation is presented a collection of papers focusing on enhancing the efficiency of integral equation solutions of antennas. A method of incorporating network principles into the method of moments is developed. Scattering parameters are determined for two structures: a coaxial-guide/radial-guide junction present in coaxial feeds of monopole and dipole antennas, and a folded coaxial guide junction proposed as part of an inductive load below the feed of the antenna. There is excellent agreement among the data obtained from the proposed method, independent MoM solutions not incorporating network principles, and measurements. An investigation into electrically switching a folded coaxial …

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Wide Area Monitoring And Control, Manish Patel Dec 2009

Wide Area Monitoring And Control, Manish Patel

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Today's interconnected power system is deregulated for wholesale power transfers. In 1996 Federal Energy Regulatory Commission provided open access of the transmission network to utilities. Since then utilities are transferring power over long distances to bring reliable and economical electric supply to their customers. As the number of wholesale power transactions taking place over an interconnected system are increasing, system operators in control areas are forced to monitor the grid on a large scale to operate it reliably. Before scheduling such a large scale power transactions, it is necessary to make sure that such transaction will not violate system operating …

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Hydrogel Compositions For Nonviral Gene Delivery, Eunhee Cho Dec 2009

Hydrogel Compositions For Nonviral Gene Delivery, Eunhee Cho

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The incorporation of nonviral vectors into biomaterial matrices has been employed to improve localization at the implant site and to protect from loss by clearance or extracellular barriers. However, several limitations such as detrimental crosslinking mechanisms, uncontrolled burst release require improved design of matrix-based gene delivery systems that provides sustained and controlled vector release as well as overcomes extracellular barriers to gene transfer in proximity to target cells. The long-term objective of this dissertation project is to provide the basis for the eventual creation of tissue engineering scaffolds that combine structural and biological activity through the creation of composite materials …

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The Development Of A Mesenchymal Stem Cell Based Bone Graft System, Sarina Sinclair Dec 2009

The Development Of A Mesenchymal Stem Cell Based Bone Graft System, Sarina Sinclair

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Greater than 5.5 million fractures are sustained by Americans each year, accounting for more than 500,000 bone graft surgeries. Bone grafts are the second most transplanted material, surpassed only by blood. The current 'gold standard' for bone grafting involves harvesting bone material from the patient's iliac crest, due to its osteoinductive properties. Unfortunately, the surgery required to harvest material from the iliac crest causes additional pain for the patient, relies on a limited amount of available bone tissue, and results in, on average, a 30% rate of donor site morbidity. Both natural and synthetic substitutes have been developed to avoid …

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An Investigation On The Use And Flexibility Of Genetic Algorithms For Logistic Regression, Sara Yoder Dec 2009

An Investigation On The Use And Flexibility Of Genetic Algorithms For Logistic Regression, Sara Yoder

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Social scientists and other users of large data sets often desire a model to predict the probability that some condition exists, such as the probability that a person has diabetes or that a credit card transaction will be fraudulent. In general, this can be done by data mining techniques, which allow multiple records of data composed of numerous independent variables and one dependent variable to be examined in a statistical fashion to make a predictive model. One particular technique used is logistic regression. Logistic regression forms a predictive model based on a set of independent variables by assigning coefficients to …

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Human Error In Mining: A Multivariable Analysis Of Mining Accidents/Incidents In Queensland, Australia And The United States Of America Using The Human Factors Analysis And Classification System Framework, Jessica Patterson Dec 2009

Human Error In Mining: A Multivariable Analysis Of Mining Accidents/Incidents In Queensland, Australia And The United States Of America Using The Human Factors Analysis And Classification System Framework, Jessica Patterson

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Historically, mining has been viewed as an inherently high-risk industry. Nevertheless, the introduction of new technology and a heightened concern for safety has yielded marked reductions in accident and injury rates over the last several decades. In an effort to further reduce these rates, the human factors associated with incidents/accidents need to be addressed. A modified version of the Human Factors Classification and Analysis System (HFCAS-MI) was used to analyze lost time accidents and high-potential incidents from across Queensland, Australia and fatal accidents from the United States of America (USA) to identify human factor trends and system deficiencies within mining. …

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Probabilistic Remediation Evaluation Model For Chlorinated Solvents Considering Uncertainty, Hailian Liang Dec 2009

Probabilistic Remediation Evaluation Model For Chlorinated Solvents Considering Uncertainty, Hailian Liang

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The complex processes and expensive costs of source and plume remediation of dense, non-aqueous phase liquid (DNAPL) complicate the decision-making process for site remediation. Selection of remediation alternatives has been a big challenge due to the lack of tools that simultaneously evaluate the effectiveness of source and plume remediation and access the uncertainties in all major parameters. In this research, a new probabilistic remediation model, Probabilistic Remediation Evaluation Model for Chlorinated solvents sites (PREMChlor), has been developed. This is achieved through linking the analytical model REMChlor to a Monte Carlo modeling simulation package GoldSim via a FORTRAN Dynamic Link Library …

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