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Air Force Institute of Technology

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Articles 5041 - 5070 of 5699

Full-Text Articles in Engineering

Interactive Control Of A Parallel Simulation From A Remote Graphics Workstation, Douglas C. Looney Dec 1993

Interactive Control Of A Parallel Simulation From A Remote Graphics Workstation, Douglas C. Looney

Theses and Dissertations

Modern military commanders are faced with an overwhelming amount of intelligence data concerning the disposition of engaging forces, The sheer volume of data produced for a single planning scenario is an obstacle to the user as well as the computer. Today’s commander requires a real-time, three- dimensional representation of the battlefield in order to assimilate the data for the management of a conflict. Parallel computation is required to complete the processing of this information in a timely manner. A network protocol is required to link the interface with the parallel simulation. The of this study is to improve user interaction …

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Design Of A Parallel Discrete Event Simulation Coprocessor, Jacob L. Berlin Dec 1993

Design Of A Parallel Discrete Event Simulation Coprocessor, Jacob L. Berlin

Theses and Dissertations

A Parallel Discrete Event Simulation Coprocessor was designed to off- load the synchronization overhead from the processors executing the application. In a multiprocessor architecture, one coprocessor executes the synchronization routines for each host processor. Speedup can be achieved when the host processor executes the application and the coprocessor concurrently executes synchronization routines. The coprocessor uses a programmable microcode control store to guarantee flexibility in the synchronization routines. The coprocessor uses an Extreme Search Associative Memory to support fast Next Event Queue NEQ management. This associative memory uses bit-serial word-parallel search logic to provide 01 insert and retrieval time of events …

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Integration And Enhancement Of The Saber Wargame, Karl S. Mathias Dec 1993

Integration And Enhancement Of The Saber Wargame, Karl S. Mathias

Theses and Dissertations

The Saber wargame is a theater-level air/land battle wargame written in Ada that is being developed for the Air Force Wargaming Center at Maxwell AFB, AL. This thesis documents how the user interface and simulation engine were integrated. Integration was accomplished by developing a portable object-oriented database system (OODBMS) interface. The interface was implemented in Ada and tied to an OODBMS also written in Ada. Using the interface, both subsystems were able to work from a consistent database and exchange information. The user interface was enhanced by converting it from the Software Technology for Adaptable Reliable Systems Ada/X Window System …

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Evaluation Of Moderate Angle Of Attack Roll Of A Dual Engine, Thrust Vectoring Aircraft Using Quantitative Feedback Theory, Kevin E. Boyum Dec 1993

Evaluation Of Moderate Angle Of Attack Roll Of A Dual Engine, Thrust Vectoring Aircraft Using Quantitative Feedback Theory, Kevin E. Boyum

Theses and Dissertations

This thesis develops an innovative approach to the design of a flight control system for performing the large-amplitude velocity vector roll maneuver at high angles of attack AOAs. A six degree of freedom aircraft model is developed from the fundamental nine-state equations of motion using a modified linearization technique. The MIMO multiple-input multiple-output Quantitative Feedback Theory QFT robust control design technique is then used to jointly address the system nonlinearities present in this maneuver and the changes in the system parameters due to changes in flight condition, treating them as structured uncertainty in the design of a three-axis rate-commanded control …

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A Study Of Two Dimensional Tapered Periodic Edge Treatments To Reduce Wideband Edge Diffraction, Russell A. Burleson Dec 1993

A Study Of Two Dimensional Tapered Periodic Edge Treatments To Reduce Wideband Edge Diffraction, Russell A. Burleson

Theses and Dissertations

This is a brief summary of a study to reduce diffraction from an infinite two dimensional edge using tapered periodic surfaces. The concept is to use the impedance characteristics of a periodic surface to create a tapered impedance much like a tapered resistance commonly used for diffraction reduction. This approach has several advantages over. tapered resistive treatments to include ease of fabrication, better engineering control of the impedance and negligible loss absorbed by the ta per. In this study, four periodic tapers were design, built and tested. These tapers were also modeled using a variety of numerical techniques. The results …

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Incorporation Of Carrier Phase Global Positioning System Measurements Into The Navigation Reference System For Improved Performance, Neil P. Hansen Dec 1993

Incorporation Of Carrier Phase Global Positioning System Measurements Into The Navigation Reference System For Improved Performance, Neil P. Hansen

Theses and Dissertations

In order to quantify the performance and accuracy of existing navigation systems, the U.S. Air Force has been using the Completely Integrated Reference Instrumentation System (CIRIS) as a baseline. CIRIS combines information from an inertial navigation unit, a barometric altimeter, and a range/range-rate system of ground transponders to obtain a navigation solution. This research explores the possibilities of enhancing CIRIS by adding measurements obtained from the Global Position System (GPS). Pure pseudorange measurement updates to the CIRIS Extended Kalman Filter form the basis of the Navigation Reference System (NRS). Applying differential corrections to the pseudorange measurements forms the basis of …

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Analysis And Simulation Of A Gps Receiver Design Using Combined Delay-Lock And Modified Tanlock Loops, George D. Harris Dec 1993

Analysis And Simulation Of A Gps Receiver Design Using Combined Delay-Lock And Modified Tanlock Loops, George D. Harris

Theses and Dissertations

The purpose of this thesis was to investigate the performance of two types of tracking loops used in Global Positioning System (GPS) receivers. The first loop, the Delay-Lock Loop (DLL), is responsible for maintaining synchronization with the received PN sequence. The second loop, the Modified Tanlock Loop (MTLL), is responsible for maintaining synchronization with the carrier signal. The performance of the two loops is investigated first separately then their performance is evaluated when operated together. This thesis is an investigation on the ability of these two loops to overcome corruption of the input signal due to noise. Expanding the dynamic …

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Investigation Into Model-Based Fuzzy Logic Control, Michael W. Logan Dec 1993

Investigation Into Model-Based Fuzzy Logic Control, Michael W. Logan

Theses and Dissertations

This thesis investigates the feasibility of a proposed hybrid linear/Fuzzy controller for nonlinear plants. The proposed controller concept is based on the use of multiple linearizations of a nonlinear plant, which describe the dynamics of perturbations about equilibrium points throughout the desired envelope of operation. A bank of linear compensators is developed, each corresponding to a linearized plant about a different equilibrium. The multiple control signals generated by the bank of compensators are then weighted and summed using Fuzzy Logic to produce a composite control perturbation signal, which is used to drive the nonlinear plant. Experiments were conducted to test …

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An Analysis Of Fm Jamming And Noise Quality Measures, Timothy N. Taylor Dec 1993

An Analysis Of Fm Jamming And Noise Quality Measures, Timothy N. Taylor

Theses and Dissertations

This thesis provides a description of FM-by-noise jamming, both at RF and at the output of the radar receiver, in terms of spectra, time-domain waveforms, and univariate probability density of amplitude. Particular emphasis is given to the case where the peak frequency deviation of the FM modulator is sufficiently small that Woodward's Theorem does not provide a good approximation of the RF spectrum. Additionally, noise quality measures which have been used to measure noise quality of radar jammers are considered theoretically and experimentally, and it is concluded that a noise measure which incorporates both a spectral measure and a probability …

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Prototype Space Fabrication Platform, James A. Bessel, James M. Ceney, David M. Crean, Edward A. Ingham, David J. Pabst Dec 1993

Prototype Space Fabrication Platform, James A. Bessel, James M. Ceney, David M. Crean, Edward A. Ingham, David J. Pabst

Theses and Dissertations

Current plans for constructing large structures in space entail fabricating the primary components, such as truss segments, on the ground and assembling them in space. This process requires an exorbitant number of support missions, and methods to minimize the number must be considered. Whenever the space shuttle is launched, its external tank is jettisoned and destroyed prior to reaching orbit. This aerospace grade aluminum structure can be carried into orbit and utilized extrusively. The Prototype Space Fabrication Platform SFP fabricates aluminum materials, reduced from external tanks, into functional trusses. The trusses are strong and can be used as the primary …

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Design Analysis Of A Combined Optical-Ladar Deep-Space Surveillance Satellite, Bradley K. Fournier Dec 1993

Design Analysis Of A Combined Optical-Ladar Deep-Space Surveillance Satellite, Bradley K. Fournier

Theses and Dissertations

This research determines the performance requirements of a combined optical LADAR space-based system in order to detect and track deep-space satellites from a near-earth orbit satellite. The research derives the necessary equations to compare both direct and heterodyne detection techniques. The selection of the candidate laser systems is based on current space developed LADAR technology. The selection of the detector, detector size, and optic size are determined in order to maximize the signal-to-noise ratio. The analysis includes the effects of beam truncation, obscuration, pixel geometry, and background radiance. The results indicate that the direct detection technique with a GaA1As semiconductor …

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Hyperspectral Analysis Of Space Objects: Signal To Noise Evaluation, Daniel Hrovat Dec 1993

Hyperspectral Analysis Of Space Objects: Signal To Noise Evaluation, Daniel Hrovat

Theses and Dissertations

Hyperspectral analysis of space objects is being considered as a means of enhancing Space Object Identification. SOI capabilities. This study develops a mathematical simulation based on fundamental radiometry principles to evaluate the feasibility of hyperspectral analysis of space objects. The study uses Signal to Noise Ratio SNR as the basis for the feasibility evaluation, and addresses the question Is there enough target signal in narrow wavelength bandwidths to conduct hyperspectral measurements of space objects The analysis characterizes the target signal and noise sources using fundamental radiometry, and develops a flexible radiometry model which calculates the target signal count rate, and …

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System Design Analysis Of A Lightweight Laser Satellite Terminal, Brian C. Page Dec 1993

System Design Analysis Of A Lightweight Laser Satellite Terminal, Brian C. Page

Theses and Dissertations

This study investigated the technological feasibility of a man- portable satellite laser communications system. Areas of interest were an end- to-end system analysis on the communications link evaluation of atmospheric effects and evaluation of semi-conductor lasers as the laser source. A literature search revealed that satellite laser communication research is primarily directed at inter-satellite links. There have been some proposed systems for space-to-ground laser communications systems, but they all utilize large fixed ground stations. The focus of this research effort is directed at a small man-portable ground station capitalizing on recent advances in semiconductor laser devices. Baseline satellite communication systems …

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Automating Satellite Range Scheduling, S. Michael Schalck Dec 1993

Automating Satellite Range Scheduling, S. Michael Schalck

Theses and Dissertations

The objective of this study was to develop a computer based satellite range scheduling SRS algorithm to create a 24 hour satellite support schedule. The algorithms goal was to schedule as many satellite support requests as possible. An iterative heuristic approach was used to schedule satellite support requests in three successive sub problems. The first sub problem involves scheduling low altitude satellite support requests using a mixed integer programming approach. The next two sub problems each involve scheduling 12 hour blocks of medium and high altitude satellite support requests, again using a mixed integer programming approach. Fourteen 24 hour schedules …

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An Evaluation Of The Software Engineering Institute's Capability Maturity Model As A Framework For Software Process Improvement At Three Air Logistics Centers, Brian G. Hermann, Raymond J. Lewis Jr. Dec 1993

An Evaluation Of The Software Engineering Institute's Capability Maturity Model As A Framework For Software Process Improvement At Three Air Logistics Centers, Brian G. Hermann, Raymond J. Lewis Jr.

Theses and Dissertations

This research sought to determine whether a relationship exists between the maturity level of the software process, as determined by the Software Engineering Institutes Capability Maturity Model SEI CMM, and the actual success of particular software projects at three US Air Force Air Logistics Centers. Project success is defined in terms of cost, schedule, and quality criteria. In addition, each organizations acceptance of the SEI assessment as well as its effectiveness in setting up follow-on process improvement programs were evaluated. Finally, the process improvement programs were reviewed individually inasmuch as these programs are the mechanisms for achieving improved quality, lower …

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An Assessment Of The Appropriateness To The Royal Australian Air Force Of A Masters Level Professional Program In Information Systems, Ralph G. L. Kettle, Joseph R. Taylor Dec 1993

An Assessment Of The Appropriateness To The Royal Australian Air Force Of A Masters Level Professional Program In Information Systems, Ralph G. L. Kettle, Joseph R. Taylor

Theses and Dissertations

This study assessed the appropriateness, to the Royal Australian Air Force RAAF, of a graduate professional program in Information Systems (IS) based on the Association for Computing Machinery’s ACM curriculum model. The ACM curriculum model is an archetype of graduate education in IS. Programs based on this model produce graduates with knowledge, skills, and abilities (KSAs) that are required by IS practitioners. The usefulness of twenty KSAs that underlie the ACM curriculum model were evaluated by 33 incumbents of RAAF information Systems Agencies and Directorate of Communications and Information Systems - Air Force. Although uncertain about the educational background suited …

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Characterization Of Fatigue Damage In A Metal Matrix Composite (Scs-6/ Ti-15-3) At Elevated Temperature, Brian P. Sanders Nov 1993

Characterization Of Fatigue Damage In A Metal Matrix Composite (Scs-6/ Ti-15-3) At Elevated Temperature, Brian P. Sanders

Theses and Dissertations

The fatigue characteristics of a unidirectional titanium based metal matrix composite (MMC) were investigated at elevated temperature (427°C). A hybrid strain controlled loading mode was used to subject the 0° and 90° laminas to fatigue. Along with the fatigue tests, microscopy and analytical modeling ware also conducted. This combination of activities led to defining the initiation and progression of damage and deformation in the MMC. Hen loading was parallel to the fiber on, the fatigue behavior was initially dominated by creep deformation of the matrix. Then, depending on the maximum strain, specimen failure was the result either fiber fractures or …

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Crew Scheduling Of Space Operations Squadrons (Sops), Marianne Idzi Nov 1993

Crew Scheduling Of Space Operations Squadrons (Sops), Marianne Idzi

Theses and Dissertations

The mission of Space Operations Squadrons is continuous support of military satellite systems. The scheduling problem associated with conducting continuous operations is threefold. The first problem is finding cyclical crew shift schedules that meet daily manning requirements, adhere to current regulations, contain a minimum number of workshift changes during consecutive duty days, and maximize the non-duty time allowed between duty shifts. The second problem is to establish a sea of criteria to evaluate alternative shift schedules. Finally, the third problem is to minimize the number of personnel required to meet the scheduling requirements stated in the first problem. This study …

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A Nonlinear Three-Dimensional Micromechanics Model For Fiber-Reinforced Laminated Composites, David D. Robertson Nov 1993

A Nonlinear Three-Dimensional Micromechanics Model For Fiber-Reinforced Laminated Composites, David D. Robertson

Theses and Dissertations

In this study, a three-dimensional micromechanics model is developed. The present capabilities of the model include both unidirectional and laminated composite layups with various types of nonlinear analysis such as a thermoelastic-plastic analysis employing the Prandtl-Reuss flow relations, a thermoviscoplastic analysis using Bodner-Partom unified constitutive theory, and an interfacial damage progression scheme based on a statistical interfacial failure criteria. Such nonlinearities are critical factors during thermomechanical fatigue TMF loading of high temperature composites. Solutions were obtained and extensive comparisons performed with existing micromechanics models, finite element analysis, and experiment with excellent results. In addition, the analysis was developed to require …

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The Application Of Simulated Annealing To Stochastic Systems, Charles B. Warrender Nov 1993

The Application Of Simulated Annealing To Stochastic Systems, Charles B. Warrender

Theses and Dissertations

Simulated Annealing was used to optimize three constrained simulation models. For each of these models, seven different acceptance functions were evaluated and compared against the performance of Local Search. These comparisons demonstrated the affect that different acceptance functions have on the performance of the algorithm. The performance was measured by the average solution quality and average efficiency obtained from several runs. The first model facilitated the implementation of Simulated Annealing using the SLAM simulation language. The configuration space was small, described by only two decision variables. It demonstrated the viability of using Simulated Annealing to optimize the variable settings in …

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Photoluminescence Spectroscopy Of Zinc Germanium Diphosphide (Zngep2), Jack E. Mccrae Sep 1993

Photoluminescence Spectroscopy Of Zinc Germanium Diphosphide (Zngep2), Jack E. Mccrae

Theses and Dissertations

Zinc germanium diphosphide (ZnGeP2) is a chalcopyrite semiconductor with strong nonlinear optical properties and potential application to Air Force interests. The characteristics of this material have been studied using photoluminescence (PL) spectroscopy. The PL spectrum is dominated by transitions from the conduction band to a deep acceptor level, and features in the spectrum suggest that more than one transition is being observed. The PL is partially polarized, and the degree of polarization appears to differ for each feature in the spectrum. The relative PL intensity of these features are seen to depend upon the wavelength of the excitation …

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A Parametric Regression Of The Cost Of Base Realignment Action (Cobra) Model, Douglas D. Hardman, Michael S. Nelson Sep 1993

A Parametric Regression Of The Cost Of Base Realignment Action (Cobra) Model, Douglas D. Hardman, Michael S. Nelson

Theses and Dissertations

This study develops a parametric model that is capable of generating accurate estimates of the costs to close Air Force installations. The new model is based upon, but much simpler to use than, the Cost of Base Realignment Action (COBRA) model. COBRA is an economic cost analysis model that requires a minimum of 250 inputs and as many as 700 inputs. The new parametric model requires just 10 input variables and was developed using least squares multiple regression. Comparison of the new parametric model to COBRA indicates that it captures 91 percent of the variance in cost estimates generated by …

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Application Of The Simplified Dow Chemical Company Relative Ranking Hazard Assessment Method For Air Combat Command Bases, Raymond A. Sable Sep 1993

Application Of The Simplified Dow Chemical Company Relative Ranking Hazard Assessment Method For Air Combat Command Bases, Raymond A. Sable

Theses and Dissertations

This study investigates the possibility of determining the hazard potential of chemicals on Air Force bases using a relative ranking hazard assessment method. Hazard assessment includes identification of hazards and evaluation of the hazards. Title III of the Superfund Amendments and Reauthorization Act of 1986 requires hazard assessments by all facilities with extremely hazardous substances to prepare release prevention plans. The purpose of the hazard assessments is to provide information to improve the spill prevention, control and countermeasures plans and to identify the substances with the highest hazard potential. Using the results from the hazard assessments, bases cam prepare plans …

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Research And Development Project Selection Tools: Probing Wright Laboratory's Project Selection Methods And Decision Criteria Using The Lateral Airfoil Concept, James E. Barger Sep 1993

Research And Development Project Selection Tools: Probing Wright Laboratory's Project Selection Methods And Decision Criteria Using The Lateral Airfoil Concept, James E. Barger

Theses and Dissertations

This research accomplished three major tasks. First it examined familiarity and usage rates for fifteen published R&D project selection methods in the context of a larger general issue, the Air Force's ability to develop and exploit technology. Wright Laboratory served as the focus for the research effort and displayed a greater tendency to use formal methods in 1993 than was shown in prior research. The laboratory's overall preference for simpler models like Checklist, Scoring, and Sorting led to a recommendation that authors familiar with the other techniques communicate them in engineering and management vernacular. Secondly, the study introduced a technological …

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Benchmarking Practices Of Air Cargo Carriers: A Case Study Approach, Mila D. Abalateo, Joni R. Lee Sep 1993

Benchmarking Practices Of Air Cargo Carriers: A Case Study Approach, Mila D. Abalateo, Joni R. Lee

Theses and Dissertations

This research effort used the benchmarking process and a case study methodology to determine what the Air Force can learn from commercial air cargo carriers. A literature search showed that the U.S. air cargo industry leaders are United Parcel Service, Federal Express, Emery Air Freight, Airborne Freight, DHL Airways, and Burlington Air Express. In addition, the 436th Aerial Port Squadron at Dover AFB, Delaware was chosen as the Air Force representative in the benchmarking study. Observations of air cargo operations and interviews with operational managers or applicable experts familiar with air cargo operations were conducted at each carrier's hub and …

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Schedule Estimating Relationships For The Engineering And Manufacturing Development Of Bomber, Transport, Tanker And Surveillance Aircraft Systems, D. Scott Boyd, Brian D. Mundt Sep 1993

Schedule Estimating Relationships For The Engineering And Manufacturing Development Of Bomber, Transport, Tanker And Surveillance Aircraft Systems, D. Scott Boyd, Brian D. Mundt

Theses and Dissertations

This study developed parametric schedule estimating relationships (SERs) for the engineering and manufacturing development (EMD) phase for nontactical aircraft systems. The potential value of this nontraditional approach to estimating schedule duration has been established by previous applications to tactical aircraft, air-launched munitions, and office buildings. Prior research suggested acquisition strategy parameters to be significant schedule drivers. For this study, data on EMD milestone dates and potential schedule drivers were collected on 56 bomber, transport, tanker, and surveillance aircraft systems. Several SERs were developed for these systems using linear regression analysis. The EMD phase was divided into subphases based on significant …

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Benchmark Production Scheduling Problems For Job Shops With Interactive Constraints, Stewart W. James, Bruno A. Mediate Jr. Sep 1993

Benchmark Production Scheduling Problems For Job Shops With Interactive Constraints, Stewart W. James, Bruno A. Mediate Jr.

Theses and Dissertations

United States Air Force (USAF) depots have expressed interest in utilizing DISASTER production scheduling software to schedule their maintenance operations. DISASTER attempts to increase system throughput by building effective schedules for system, constraint resources. However, when a system contains multiple, interactive constraints, DISASTER builds the constraint schedules one at a time. Since each successive schedule must adhere to timing restrictions imposed by previous constraint schedules, the quality of the schedules produced by DISASTER is dependent upon the sequence in which the constraints are scheduled. This thesis first developed a set of benchmark problems which provide a diversity of scheduling scenarios. …

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An Analysis Of The Performance-Risk Trade-Off In Source Selection Decision Making, Richard G. Pierce, Jeffrey E. Wainwright Sep 1993

An Analysis Of The Performance-Risk Trade-Off In Source Selection Decision Making, Richard G. Pierce, Jeffrey E. Wainwright

Theses and Dissertations

Each year the Air Force awards weapon system contracts worth billions of dollars using the source selection process. In the source selection, performance and risk assessments are evaluated to determine the best proposal; the proposal that gives the best overall value. The purpose of this research was to investigate the performance/risk trade-off in the source selection decision making process. The study also examined the effect individual risk propensities and the nature of item being evaluated have on the performance/risk trade-off decisions. Air Force acquisition personnel stationed at Aeronautical Systems Center, Wright-Patterson AFB, OH, who had participated in a source selection …

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Scheduling A Medium-Sized Manufacturing Shop: A Simulation Study, Daniel J. Mcfeely Sep 1993

Scheduling A Medium-Sized Manufacturing Shop: A Simulation Study, Daniel J. Mcfeely

Theses and Dissertations

This study examined the application of simple-to-use, low cost scheduling methods to the operating environment of a medium-sized manufacturing shop. Computer simulation was used to evaluate eighteen different scheduling algorithms, each the result of the combination of a loading and a sequencing rule; due date setting was not considered since due dates are exogenously set. The loading rules investigated were Minimum Machine Required, Lowest Average WIP, and Lowest Average Aggregate Priority Level. The sequencing rules investigated were Priority, EDD, FIS, SPT, Slack, and Slack Ratio. The scheduling algorithms were evaluated against performance measures of mean tardiness, mean flowtime, mean percentage …

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A Refinement Of Risk Analysis Procedures For Trichloroethylene Through The Use Of Monte Carlo Method In Conjunction With Physiologically Based Pharmacokinetic Modeling, William J. Cronin Iv, Eric J. Oswald Sep 1993

A Refinement Of Risk Analysis Procedures For Trichloroethylene Through The Use Of Monte Carlo Method In Conjunction With Physiologically Based Pharmacokinetic Modeling, William J. Cronin Iv, Eric J. Oswald

Theses and Dissertations

This study refines risk analysis procedures for trichloroethylene (TCE) using a physiologically based pharmacokinetic (PBPK) model in conjunction with the Monte Carlo method. The Monte Carlo method is used to generate random sets of model parameters, based on the mean, variance, and distribution types. The procedure generates a range of exposure values for human excess lifetime cancer risk of lxl0 (exp-6), based on the upper and lower bounds and the mean of a 95% confidence interval. Risk ranges were produced for both ingestion and inhalation exposures. Results are presented in a graphical format to reduce reliance on qualitative discussions of …

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