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Full-Text Articles in Engineering

Automated Quadrilateral Coarsening By Ring Collapse, Mark William Dewey Mar 2008

Automated Quadrilateral Coarsening By Ring Collapse, Mark William Dewey

Theses and Dissertations

In most finite element analysis, a uniform mesh is not the optimum way to model the problem. Mesh adaptation is the ability to modify a finite element model to include regions of the mesh with higher and lower node density. Mesh adaptation has received extensive study in both computational mechanics and computer graphics to increase the resolution or accuracy of the solution in specific areas. The algorithm developed in this thesis, the Automated Quadrilateral Coarsening by Ring Collapse (AQCRC) algorithm, provides a unique solution to allow conformal coarsening of both structured and unstructured quadrilateral finite element meshes. The algorithm is …

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Parallel Processing Of Reactive Transport Models Using Openmp, Jared D. Mclaughlin Mar 2008

Parallel Processing Of Reactive Transport Models Using Openmp, Jared D. Mclaughlin

Theses and Dissertations

Transport codes are beginning to be parallelized in order to allow more complex add-ons, such as geochemical packages, to utilize finer, more accurate grids, and to reduce solution times making stochastic and Monte Carlo simulations more feasible. Most codes parallelized via MPI (message passing interface) offer good results, but require the development of a new parallel code. OpenMP, the shared-memory standard, offers incremental parallelization, allowing sequential codes to remain relatively intact with minimal changes or additions. OpenMP allows speedup to be seen on personal computers with dual processors or greater, unlike some other parallelization approaches that require a supercomputer. An …

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Development Of A Quality Improvement Method For International Manufacturing, Andrew J. Strong Mar 2008

Development Of A Quality Improvement Method For International Manufacturing, Andrew J. Strong

Theses and Dissertations

Many companies are entering the international manufacturing arena. The continued expansion of the global market suggests that international manufacturing will grow. Among other concerns, the difficulty of producing high quality in some countries suggests that it is critical that companies using international locations for manufacturing find methods to better monitor and improve quality. The purpose of this research was to develop and test a method for quality improvement in an offshore environment. This method would be specifically applicable to a third-party logistics company (3PL), where the 3PL is a United States company that brokers manufacturing in China, networks to multiple …

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Robust Parameterization Schema For Cax Master Models, Courtney L. Berglund Mar 2008

Robust Parameterization Schema For Cax Master Models, Courtney L. Berglund

Theses and Dissertations

Today's engineering companies rely heavily on an engineer's ability to use computers to analyze and optimize designs. With this use of computers in the design process, products undergo multiple design iterations between preliminary concept and final form. This in turn results in Computer Aided Design (CAD) models being passed from one discipline to the next. In attempts to keep consistency within the design process, an industry wide shift towards the use of CAD master models is taking place. With this change to master models, manufacturing and engineering development companies are attempting to more fully employ the use of parametrics in …

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An Analysis Of Construction Cost And Schedule Performance, Michael J. Beach Mar 2008

An Analysis Of Construction Cost And Schedule Performance, Michael J. Beach

Theses and Dissertations

Cost and schedule performance are widely accepted in the literature and in industry as effective measures of the success of the project management effort expended. Earned Value Analysis (EVA) offers many metrics to objectively measure cost and schedule performance of many different types of projects. The author utilized EVA to objectively measure the cost and schedule performance of completed United States Air Force (AF) Military Construction (MILCON projects from 1990 to 2005. The impact of Major Command (MAJCOM), Construction Agent (CA), and facility type (CATCODE) and the combination of these variables on the EVA metrics of Cost Performance Index (CPI), …

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Satisficing Theory And Non-Cooperative Games, Matthew S. Nokleby Mar 2008

Satisficing Theory And Non-Cooperative Games, Matthew S. Nokleby

Theses and Dissertations

Satisficing game theory is an alternative to traditional non-cooperative game theory which offers increased flexibility in modeling players' social interactions. However, satisficing players with conflicting attitudes may implement dysfunctional behaviors, leading to poor performance. In this thesis, we present two attempts to "bridge the gap" between satisficing and non-cooperative game theory. First, we present an evolutionary method by which players adapt their attitudes to increase raw payoff, allowing players to overcome dysfunction. We extend the Nash equilibrium concept to satisficing games, showing that the evolutionary method presented leads the players toward an equilibrium in their attitudes. Second, we introduce the …

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Real-Time Forward Urban Environment Perception For An Autonomous Ground Vehicle Using Computer Vision And Lidar, Christopher Richard Greco Mar 2008

Real-Time Forward Urban Environment Perception For An Autonomous Ground Vehicle Using Computer Vision And Lidar, Christopher Richard Greco

Theses and Dissertations

The field of autonomous vehicle research is growing rapidly. The Congressional mandate for the military to use unmanned vehicles has, in large part, sparked this growth. In conjunction with this mandate, DARPA sponsored the Urban Challenge, a competition to create fully autonomous vehicles that can operate in urban settings. An extremely important feature of autonomous vehicles, especially in urban locations, is their ability to perceive their environment. The research presented in this thesis is directed toward providing an autonomous vehicle with real-time data that efficiently and compactly represents its forward environment as it navigates an urban area. The information extracted …

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The Concept Design Of A Split Flow Liquid Hydrogen Turbopump, Michael A. Arguello Mar 2008

The Concept Design Of A Split Flow Liquid Hydrogen Turbopump, Michael A. Arguello

Theses and Dissertations

An initial design of a split flow liquid hydrogen turbopump for the Dual Expander Aerospike Nozzle (DEAN) upper stage engine was completed. The engine nozzle is an annular aerospike. The engine cycle requires a combustion chamber pressure of 1,740 psia. The DEAN is designed to deliver 57,200 lbf of thrust and 472 seconds of Isp. The turbopump design was completed using a meanline software tool. The design consists of a single piece rotor, with a two-stage pump and radial inflow turbine. The turbopump flow rates are 15.1 and 7.55 lbm/s into the first and second stage, respectively. The first and …

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An Experimental Technique For Developing Intermediate Strain Rates In Ductile Metals, Hugh E. Gardenier Iv Mar 2008

An Experimental Technique For Developing Intermediate Strain Rates In Ductile Metals, Hugh E. Gardenier Iv

Theses and Dissertations

Quantifying the strain-rate sensitive dynamic properties of structural materials is an important area of research in the solid mechanics field. Property evaluation is typically accomplished using dynamic tests which involve rapid loading or impact of specimens. In these tests, inertial forces and wave propagation make it difficult to accurately record the material response to a loading condition at an equivalent location. Furthermore, these tests typically generate high strain rates (in excess of 103 s−1) and an experimental method for generating rates of strain in the intermediate strain rate regime which is relatively simple, low cost, and reliable …

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Discrete Counting Of Short Lived Isotopes With Low Background Detectors, David E. Mather Mar 2008

Discrete Counting Of Short Lived Isotopes With Low Background Detectors, David E. Mather

Theses and Dissertations

We consider radiation counting experiments used to measure quantities of materials that are short-lived with respect to the count durations. The HPS 13.31 statistical analysis seriously overestimates the uncertainty when the quantity and background are very low. We consider the case in which the objective is to quantify the number of atoms, n, that were present in a sample when it was drawn. Mathews and Gerts [JRNC, 2008] analyzed this case and developed formulas for the probability distribution of n, in order to develop experiment design processes that minimize the smallest detectable quantity of material, thus maximizing sensitivity for the …

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Analysis Of Multi-Layered Materials Under High Velocity Impact Using Cth, Jason K. Lee Mar 2008

Analysis Of Multi-Layered Materials Under High Velocity Impact Using Cth, Jason K. Lee

Theses and Dissertations

Multi-layer armor containing ceramic and metallic layers has become more common in the past two decades. Typically, ceramics have high compressive strength which combined with their low density make them highly desirable for armor applications. This research effort numerically simulates high velocity impact of cylindrical projectiles on multi-layer metallic and ceramic targets of finite thickness. The impact of the projectile occurs normal to the surface of the target. The projectiles used are made of either S7 tool steel or tungsten. The targets consist of either rolled homogeneous armor, 4340 steel and boron carbide ceramic or rolled homogeneous armor and boron …

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On-Board Thermal Management Of Waste Heat From A High-Energy Device, Nathan D. Klatt Mar 2008

On-Board Thermal Management Of Waste Heat From A High-Energy Device, Nathan D. Klatt

Theses and Dissertations

The use of on-board high-energy devices such as megawatt lasers and microwave emitters requires aircraft system integration of thermal devices to either rid waste heat or utilize it in other areas of the aircraft. Non-chemical lasers are among the most challenging applications due to the low cooling temperature requirements (67 °F) and high waste heat generation times of order 20 s. (Microwave devices will be cooled at 157.7 °F.) One plan calls for the rapidly generated waste energy to be stored prior to peripheral utilization, with subsequent removal of the heat over a 5-10 minute span. A method is presented …

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Computational Design Of Upperstage Chamber, Aerospike, & Cooling Jacket For Dual-Expander Rocket Engine, David F. Martin Ii Mar 2008

Computational Design Of Upperstage Chamber, Aerospike, & Cooling Jacket For Dual-Expander Rocket Engine, David F. Martin Ii

Theses and Dissertations

To increase the performance of the current US satellite launch capability, new rocket designs must be undertaken. One concept that has been around since the 50s but yet to be utilized on a launch platform is the aerospike, or plug nozzle. The aerospike nozzle concept demonstrates globally better performance compared to a conventional bell nozzle, since the expansion of the jet is not bounded by a wall and therefore can adjust to the environment by changing the outer jet boundary. A dual-expander aerospike nozzle (DEAN) rocket concept would exceed the Integrated High Payoff Rocket Propulsion Technology initiative (IHPRPT) phase three …

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Optimal Guidance Of A Relay Mav For Isr Support Beyond Line-Of-Sight, John H. Hansen Mar 2008

Optimal Guidance Of A Relay Mav For Isr Support Beyond Line-Of-Sight, John H. Hansen

Theses and Dissertations

This thesis developed guidance laws to optimally position a relay Micro-UAV (MAV) to provide an operator with real-time Intelligence, Surveillance, and Reconnaissance (ISR) by relaying communication and video signals when there is no line-of-sight between the operator at the base and the rover MAV performing the ISR mission. The ISR system consists of two MAVs, the Relay and the Rover, and a Base. The Relay strives to position itself to minimize the radio frequency (RF) power required for maintaining communications between the Rover and the Base, while the Rover performs the ISR mission, which may maximize the required RF power. …

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Finite Element Simulation Methods For Dry Sliding Wear, Aaron J. Chmiel Mar 2008

Finite Element Simulation Methods For Dry Sliding Wear, Aaron J. Chmiel

Theses and Dissertations

The Holloman High Speed Test Track is a rocket sled track for testing at hypersonic velocities. However, there are customers that desire to test at even greater velocities. In order to achieve higher velocities there are several phenomena that must be overcome. One important phenomenon is wear of the shoe that holds the sled on the rail. This research is a look at the feasibility of using finite element analysis to predict the wear of the shoe during a test run down the track. Two methods are investigated, one is a macro-scale, incremental method utilizing traditional wear equations from Archard, …

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Filtered Rayleigh Scattering Measurements In A Buoyant Flow Field, Steven M. Meents Mar 2008

Filtered Rayleigh Scattering Measurements In A Buoyant Flow Field, Steven M. Meents

Theses and Dissertations

Filtered Rayleigh Scattering (FRS) is a non-intrusive, laser-based flow characterization technique that consists of a narrow linewidth laser, a molecular absorption filter, and a high resolution camera behind the filter to record images. Gases of different species have different molecular scattering cross-sections that become apparent as they pass through the interrogating laser light source, and this difference is used to discriminate between the different gaseous components. This study focuses on the behavior of a buoyant helium jet exiting horizontally into ambient air, and more specifically this jet’s tendency to form side lobes that are discharged from the core fluid under …

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A Static Aeroelastic Analysis Of A Flexible Wing Mini Unmanned Aerial Vehicle, Nathan A. Pitcher Mar 2008

A Static Aeroelastic Analysis Of A Flexible Wing Mini Unmanned Aerial Vehicle, Nathan A. Pitcher

Theses and Dissertations

The static aeroelastic behavior of the Nighthawk mini unmanned aerial vehicle is examined using a combined experimental and computational approach. Three wings are examined. In order of increasing stiffness they are: a flexible wing, a stiff wing, and a fictitious rigid wing with zero deflection. Photogrammetry is used during wind tunnel testing to measure the average deflected shape of the flexible and stiff wings during flight. The independent variables during wind tunnel tests are angle of attack (ranging from −5.1° through 13.4°) and velocity, which is 20 mph, 30 mph, and 40 mph. Roll angle and yaw angle are control …

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Biomimetic Micro Air Vehicle Testing Development And Small Scale Flapping-Wing Analysis, Craig E. Svanberg Mar 2008

Biomimetic Micro Air Vehicle Testing Development And Small Scale Flapping-Wing Analysis, Craig E. Svanberg

Theses and Dissertations

The purpose of this research was to develop testing methods capable of analyzing the performance of a miniature flapping-wing mechanism that can later be adapted to a biomimetic micro air vehicle (MAV). Three small scale flapping mechanisms capable of single plane flapping, flapping with active pitch control, and flapping/pitch with out-of-plane movement were designed using SolidWorks. The flapping-only model was fabricated on an Objet Eden 500V 3-dimensional printer. The flapping mechanism was mounted on an aluminum plate supported by air bearings, and thrust was measured for a variety of conditions. The testing was conducted using wings composed of carbon fiber …

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Analyzing Carbohydrate-Based Regenerative Fuel Cells As A Power Source For Unmanned Aerial Vehicles, Olek Wojnar Mar 2008

Analyzing Carbohydrate-Based Regenerative Fuel Cells As A Power Source For Unmanned Aerial Vehicles, Olek Wojnar

Theses and Dissertations

Based on current capabilities, we examine the feasibility of creating a carbohydrate-based regenerative fuel cell (CRFC) as the primary power source for unmanned aerial vehicles (UAV) for long endurance missions where station keeping is required. A CRFC power system is based on a closed-loop construct where carbohydrates are generated from zooxanthellae, algae that create excess carbohydrates during photosynthesis. The carbohydrates are then fed to a carbohydrate fuel cell where electric power is generated for the UAV’s propulsion, flight control, payload, and accessory systems. The waste products from the fuel cell are used by the zooxanthellae to create more carbohydrates, therefore …

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Minimizing Secular J2 Perturbation Effects On Satellite Formations, Jonathan W. Wright Mar 2008

Minimizing Secular J2 Perturbation Effects On Satellite Formations, Jonathan W. Wright

Theses and Dissertations

The purpose of this thesis is to examine the secular effects of the J2 oblateness perturbation on close proximity satellites. The main objective is to analyze the deputy’s position and velocity with respect to the chief and adjust the initial conditions of the deputy in an attempt to minimize the secular effects of J2 perturbations. Previous work has provided a method of obtaining a closed form solution for J2 invariance with co-planar orbits. Therefore, this work will primarily consider deputy orbits that experience motion outside of the chief’s orbital plane. Upon determining the required initial conditions, the …

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Modeling Gps Satellite Orbits Using Kam Tori, Rachel M. Derbis Mar 2008

Modeling Gps Satellite Orbits Using Kam Tori, Rachel M. Derbis

Theses and Dissertations

Global Positioning System (GPS) satellite orbits are modeled using Kolmogorov, Arnold, Moser (KAM) tori. Precise Global Positioning System satellite locations are analyzed using Fourier transforms to identify the three basis frequencies in an Earth Centered, Earth Fixed (ECEF) rotating reference frame. The three fundamental frequencies are 1) the anomalistic frequency, 2) a combination of earth’s rotational frequency and the nodal regression rate, and 3) the apsidial regression rate. A KAM tori model fit to the satellite data could be used to predict future satellite locations. This model would allow rapid determination with fewer computational requirements than the typical method of …

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Demonstration Of A Strategy To Perform Two-Dimensional Diode Laser Tomography, Ryan N. Givens Mar 2008

Demonstration Of A Strategy To Perform Two-Dimensional Diode Laser Tomography, Ryan N. Givens

Theses and Dissertations

Demonstration of a strategy to perform two-dimensional diode laser tomography using a priori knowledge from symmetry arguments and computational fluid dynamic (CFD) calculations is presented for a flat flame burner. The strategy uses an optimization technique to determine flame diameter and location using a vector quantization approach. Next, the variance in a training set, produced from CFD calculations, is captured using principal components analysis. The information in the training set allows interpolation between beam paths resulting in temperature and density maps. Finally, the TDLAS temperature and density maps are shown to agree with traditional thermocouple measurements of the flat flame …

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Evaluation Of The Applicability Of The Interactive Highway Safety Design Model To Safety Audit Of Two-Lane Rural Highways, Kaitlin Chuo Mar 2008

Evaluation Of The Applicability Of The Interactive Highway Safety Design Model To Safety Audit Of Two-Lane Rural Highways, Kaitlin Chuo

Theses and Dissertations

The Interactive Highway Safety Design Model (IHSDM) is a suite of software developed by the Federal Highway Administration (FHWA) for monitoring and analyzing two-lane rural highways in the United States. As IHSDM is a fairly "young" program a limited amount of research has been conducted to evaluate its practicability and reliability. To determine if IHSDM can be adopted into the engineering decision making process in Utah, a study was conducted under the supervision of the Utah Department of Transportation (UDOT) to evaluate its applicability to audit safety of two-lane rural highways in Utah. IHSDM consists of six modules: Policy Review …

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Thermal Characterization Of A Hall Effect Thruster, Alex M. Bohnert Mar 2008

Thermal Characterization Of A Hall Effect Thruster, Alex M. Bohnert

Theses and Dissertations

The thermal characteristics of a Hall thruster directly influence thruster and spacecraft design. High temperatures affect the magnetic coil capabilities and cause higher insulator erosion rates, influencing both thruster performance and lifetime. The Hall thruster transfers heat through both radiation and conduction, and the spacecraft must handle this additional thermal energy. An infrared camera provides a non-intrusive method to analyze the thermal characteristics of an operational Hall thruster. This thesis contains the thermal analysis of a Busek Co. Inc. 200 W Hall thruster, using a FLIR ThermaCAM SC640 infrared camera. The Space Propulsion Analysis and System Simulator Laboratory at the …

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Crew Exploration Vehicle (Cev) Skip Entry Trajectory, Emre Kaya Mar 2008

Crew Exploration Vehicle (Cev) Skip Entry Trajectory, Emre Kaya

Theses and Dissertations

This research effort develops a program using MATLAB® to solve the equations of motion for the atmospheric reentry of the Crew Exploration Vehicle (CEV) which is assumed to be in the phase of a lunar return trajectory that could be initiated any time during the mission. The essential reason for this research is to find a solution for the problem of an unplanned lunar return in addition to the normal procedures. Unlike Apollo type missions, the CEV would still be able to land on any preplanned available landing sites without any additional delay. In Apollo type missions, the return phase …

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Determination Of Static And Dynamic Stability Derivatives Using Beggar, Michael E. Bartowitz Mar 2008

Determination Of Static And Dynamic Stability Derivatives Using Beggar, Michael E. Bartowitz

Theses and Dissertations

The static and dynamic pitch and roll stability derivatives of a finned, axisymmetric missile known as the Basic Finner were examined using a Computational Fluid Dynamics (CFD) approach. Stability derivatives are used to characterize vehicle motion, and knowledge of them is critical to the design of stable uncontrolled vehicles and control systems for controlled vehicles. Using CFD to characterize the motion of new munition designs has the potential to improve overall performance and reduce research and testing costs. The present analysis simulated forced oscillation and free oscillation of the Basic Finner model using the Air Force SEEK EAGLE Office's Beggar …

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A Comparison Of Moiré Interferometry And Digital Image Correlation, Ryan J. Davidson Mar 2008

A Comparison Of Moiré Interferometry And Digital Image Correlation, Ryan J. Davidson

Theses and Dissertations

This research effort studied the effect of subset size and step size on the spatial resolution and accuracy of Digital Image Correlation (DIC). In addition, DIC was compared with moiré interferometry in an attempt to give future researchers guidance on which method would be appropriate for their research. Strains fields were calculated from displacement fields measured by each method. The strain fields were then compared. The main findings of the research were that: increased subset sizes caused a smoothing of data; increased step sizes reduced the resolution of the data; DIC is an accurate displacement measurement technique; the spatial resolution …

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Characterization And Control Of Carbon Dioxide Seed Particle Image Velocimetry, Bartt G. Greene Mar 2008

Characterization And Control Of Carbon Dioxide Seed Particle Image Velocimetry, Bartt G. Greene

Theses and Dissertations

Particle Image Velocimetry (PIV) data was acquired in two separate supersonic wind tunnels with carbon dioxide (CO2) particles utilized as the seed material. Previous work in clean seeding showed CO2 could be used as seed material to produce velocity maps. This research provides the first quantitative assessment of particle response, particle size control via purge gas, and scalability using CO2 particles. A variety of feed tube and shroud configurations, in combination with varying volumetric flow rates of purge air were measured using a laser diffraction device. The CO2 particles were injected into the stilling chamber …

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Demonstrative Maneuvers For Aircraft Agility Predictions, David M. Hall Mar 2008

Demonstrative Maneuvers For Aircraft Agility Predictions, David M. Hall

Theses and Dissertations

This study was motivated by a need to develop a reliable method of predicting the agility characteristics of various aircraft. To fully investigate the agility of an aircraft, maneuvers which push the limits of an aircraft’s maneuvering capabilities must be simulated. In these cases, classic trajectory optimization techniques either require too many assumptions for a realistic solution or require a good guess of the final solution before the problem is even attempted. This study investigated both the utility of pseudospectral optimization methods for robust trajectory optimization as well as the potential for demonstrating differences in aircraft agility characteristics of several …

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Direct Initiation Through Detonation Branching In A Pulsed Detonation Engine, Alexander R. Hausman Mar 2008

Direct Initiation Through Detonation Branching In A Pulsed Detonation Engine, Alexander R. Hausman

Theses and Dissertations

Pulsed Detonation Engines are currently limited in operating frequency to the order of 40 Hz due to lengthy ignition and deflagration to detonation transition (DDT) times. An experimental study is conducted to determine the requirements necessary to eliminate these constraints through the concept of direct initiation. A branched detonation crossover setup is constructed and the operational requirements are determined. This research demonstrates the ability to directly initiate a detonation in a vacant tube from a detonation obtained through detonation branching. Using a hydrogen-air mixture, a tail-to-head detonation branching is achieved in which a detonation is seen to propagate from a …

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