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Articles 11221 - 11250 of 11490
Full-Text Articles in Engineering
A Fully Coupled, Automated Formation Control System For Dissimilar Aircraft In Maneuvering Formation Flight, Paul R. Rohs
A Fully Coupled, Automated Formation Control System For Dissimilar Aircraft In Maneuvering Formation Flight, Paul R. Rohs
Theses and Dissertations
This study developed a fully automated formulation control system, capable of controlling a number of like or dissimilar aircraft in maneuvering formation flight. C-130 fixed wing aircraft and H-53 helicopters were modelled in various formulations and simulated through a mix of maneuvers. External formation guidance was assumed as a single data burst of nominal function guidance commands and separation distances for each wing aircraft in the formation. No communication was assumed between formation aircraft. Wing aircraft track lead aircraft maneuvering with an ideal on-board sensor, maneuvering to maintain relative position. It was determined that lead aircraft inputs must be attenuated …
Green's Function Approach To The Atmospheric Albedo Neutron Transport Problem, Donald R. Culp Jr.
Green's Function Approach To The Atmospheric Albedo Neutron Transport Problem, Donald R. Culp Jr.
Theses and Dissertations
This study investigated the reflection of neutron radiation off of the earth's upper atmosphere, with the goal of generating a quick-running computer algorithm to estimate the albedo free field flux at any point above the atmosphere. This thesis involved analytic development in the construction of the algorithm and employed Monte Carlo simulation for generating the energy and angle distributions of the reflected radiation. The Green's function approach to modeling the neutron transport process involved approximating each energy bin of the source spectrum as a Dirac pulse in energy and summing the contribution from each source bin. The computer program integrates …
Calculated Point Defect Properties Of The Intermetallic Compounds Nickel Titanium (Niti) And Iron Titanium (Feti), Russell T. Lutton
Calculated Point Defect Properties Of The Intermetallic Compounds Nickel Titanium (Niti) And Iron Titanium (Feti), Russell T. Lutton
Theses and Dissertations
Atomistic simulation with a modified version of the DYNAMO code was used to calculate the point defect properties of the intermetallic compounds nickel titanium and iron titanium. The calculated energies are believed to be experimentally accurate to within +/- 0.1 eV. Vacant Ni or Fe lattice sites were preferred and had energies of 6.356 eV for NiTi and 5.899 eV for FeTi. Removing a Ti atom resulted in a neighboring antisite defect caused by migration of a Ni or Fe atom into the vacant Ti site. These configurations had energies of 7.024 eV for NiTi and 6.336 eV for FeTi. …
Mapping Efficient Numerical Methods To The Solution Of Multiple Objective Linear Programs, Michael A. Shields
Mapping Efficient Numerical Methods To The Solution Of Multiple Objective Linear Programs, Michael A. Shields
Theses and Dissertations
This investigation was initiated to increase the speed, accuracy and capacity of m-simplex algorithms for solving multiple objective linear programming problems. Specifically, improvements were sought through the application of general numerical techniques. It soon became apparent that the m- simplex algorithm, like the simplex algorithm, is heavily dependent upon the technology of solving related systems of linear equations. The numerical arguments for the application of LU triangular matrix factorization techniques to simplex computations are well known. OF special significance to m-simplex performance is the case of rank-k updates to basis factorizations. A stable and efficient LU approach to the rank-k …
New Modified Anderson-Darling And Cramer-Von Mises Goodness-Of-Fit Tests For A Normal Distribution With Specified Parameters, Goksel Kahya
New Modified Anderson-Darling And Cramer-Von Mises Goodness-Of-Fit Tests For A Normal Distribution With Specified Parameters, Goksel Kahya
Theses and Dissertations
This thesis improves the powers of the Anderson-Darling and Cramer-von Mises goodness-of-fit tests using the mean rank and the median rank plotting positions. A Monte Carlo simulation of 5000 repetitions is used to generate the critical values from n =4 through n =80 for certain significance levels. An extensive power study is performed to compare the powers of the modified tests to the known tests for the uniform, the exponential, the double exponential, the lognormal, and the Weibull distributions. The power of the A-D tests modified by the median rank plotting and the mean rank plotting position are approximately 0.01% …
A Goodness-Of-Fit Test For A Family Of Two Parameter Weibulls With Known Shape Using Minimum Distance Estimation Of Parameters, John S. Crown
A Goodness-Of-Fit Test For A Family Of Two Parameter Weibulls With Known Shape Using Minimum Distance Estimation Of Parameters, John S. Crown
Theses and Dissertations
This research is to produce a modified Anderson-Darling goodness of fit test for the Weibull distribution when the location parameter is found by minimum distance estimation, the shape parameter is assumed known, and the MLE is used for the scale parameter. The critical values for the Anderson-Darling test are generated via Monte Carlo simulation when both the Anderson-Darling and Cramer-Von Mises distance statistics are minimized. These critical values are then used for a power study. The Monte Carlo simulation used 5000 repetitions for sample sizes of 5,8,12,15,16,20 and 25 with the Weibull shape parameter of . 5(.5)4.0. The power study …
Hardware Upgrade Of A Segmented Drum Assay System, Claude A. Irvine
Hardware Upgrade Of A Segmented Drum Assay System, Claude A. Irvine
Theses and Dissertations
This paper describes the conversion of a DEC PDP-11/05 computer system, previously used in Canberra's Model 2220B segmented gamma scanner, with an IBM PC. Two tasks necessary for completion of the project involved reestablishing communications with a Canberra Series 35+ multi-channel analyzer and a scan table controller. An additional serial/parallel card was installed in the PC to reinstate comunications with the multi-channel analyzer. For computer control of scan table controller operations a digital input/output card was used along with an external electromechanical relay board; when implemented together this hardware setup replaces functions that were normally processed through a motion control …
The Development Of An Officer Training School Board Score Prediction Method Using A Multi-Board Approach, Sandra C. Niemi
The Development Of An Officer Training School Board Score Prediction Method Using A Multi-Board Approach, Sandra C. Niemi
Theses and Dissertations
One phase in the Officer Training School (OTS) selection process is meeting a selection board. Recruiting Services (HQ ATC/RS) currently uses a regression model (based on data from one board) to evenly distribute 'quality' among the different panels in the selection boards. HQ ATC/RS wanted a method of predicting board scores based on data from multiple boards. This study used the results from eighteen boards and 9215 applicants to develop and validate a multi-board regression model for each of five application categories. Comparisons between the two models showed mixed results. In two categories, non- rated operations and technical, the single-board …
A Prototype Meta-Language And Automated Translator For Decision Analysis Problem Formulation, Jerry R. Puyear
A Prototype Meta-Language And Automated Translator For Decision Analysis Problem Formulation, Jerry R. Puyear
Theses and Dissertations
This thesis research effort develops a prototype meta-language for decision analysis problem description and automated software to translate the meta-language into a format useable by decision analysis software solvers. MELDA, the metalanguage developed, makes use of special symbols to provide a succinct language for the automation environment yet provides the means for user comprehension. Complete syntax and implementation rules are included. The MELADA translator software developed, DAT, stores the data given by MELADA in a file using prototype standard format, DASF, designed to hold all required data to solve a problem. DAT provides error checking and a message output file. …
Locating Direction Finders In A Generalized Search And Rescue Network, Jean M. Steppe
Locating Direction Finders In A Generalized Search And Rescue Network, Jean M. Steppe
Theses and Dissertations
A multiobjective linear programming approach is applied to the problem of locating receiving stations and HFDF receivers in a search and rescue network in order to maximize the expected number of distress signals that are geolocated. The multiobjective formulation is made up of two contrasting objectives: one maximizes the expected accurate lines of bearing, and one minimizes the excess coverage in the network. The individual objectives are weighted and combined into a composite objective function. The resulting problem is expressed as a two-stage network flow problem and is solved using SAS LP with a limited number of binary variables. The …
An Interactive Life Cycle Cost Forecasting Tool, John A. Gibson Iv
An Interactive Life Cycle Cost Forecasting Tool, John A. Gibson Iv
Theses and Dissertations
Enhancements were applied to an existing tool designed to estimate life cycle costs. These enhancements provide greater ease of data manipulation, additional options in developing models, and the ability to make modifications to suit the needs of the user. Life cycle costs can be generated quickly and easily. Analysis proved the amount of work done by the computer could be reduced with no loss of information. Additionally, the paths available to the user are shown graphically through flow charts--aiding in the learning process. The efforts of the user can now be directed towards developing models instead of spending those efforts …
Enhancements To Pcrsm, Laurie M. Rouillard
Enhancements To Pcrsm, Laurie M. Rouillard
Theses and Dissertations
The purpose of this study was to enhance the capability of PCRSM, a personal computer based decisions support system, to perform response surface methodology. PCRSM was enhanced to allow the printing of graphical displays such as residual plots and to provide the capability to decode the regression equation back to the original variables. Reverse documentation of the prototype was also developed to describe the interfacing of the individual executable modules and development environment. Response surface methodology is a group of statistical tools used to analyze the relationships between predictors (input variables) and responses (output variables).
Saber: A Theater Level Wargame, William F. Mann Iii
Saber: A Theater Level Wargame, William F. Mann Iii
Theses and Dissertations
This thesis provides a foundation to build a new theater level computerized wargame for the Air Force Wargaming Center, Maxwell AFB, AL to replace the Theater War Exercise (TWX), also known as Agile. Given a recently developed land battle, this thesis' effort links US Air Force doctrine with a conceptual model's framework and designs a new air battle module. The integration of both the air and land battles forms a new game, Saber. This thesis redefines the ground combat units of the land battle, and adds theater air defense units, bases and aircraft packages. This thesis introduces stochastic attrition between …
Analysis Of The Effects Of The Commander's Battle Positioning On Unit Combat Performance, Thomas I. Pratt
Analysis Of The Effects Of The Commander's Battle Positioning On Unit Combat Performance, Thomas I. Pratt
Theses and Dissertations
The purpose of this study was to determine the effect of the Commander's battle positioning on unit combat performance. Research was focused on analyzing the location of the Battalion/Task Force Commander during daytime deliberate attacks conducted at the U.S. Army's National Training Center, Fort Irwin, CA. Forty battles, from January 1986 to September 1989, provided the basis for this study. Information that described the Commander's location, a general description of the battle, and unit measures of effectiveness, was collected for each battle and put in a format that allowed for ease of analysis. This study database was explored using numerous …
A Network Flow And Goal Programming Approach To Modeling The Impact Of Pre-Accession Training To The Trained Personnel Requirements Process, William J. Beveridge
A Network Flow And Goal Programming Approach To Modeling The Impact Of Pre-Accession Training To The Trained Personnel Requirements Process, William J. Beveridge
Theses and Dissertations
HQ ATC was tasked to analyze the impact of pre-accession training to the Trained Personnel Required (TPR) and training production process. Pre- accession training is a policy of providing contracted initial skills training to enlistees prior to entering basic military training. The purpose of this study was to develop a method to model the impact of pre-accession training. A network modeling and goal programming approach was used. Comparisons between the current training policy and a pre-accession training policy were made. Sensitivity was conducted on the impact of a balk rate on the new policy. The balk rate is the percent …
A Study Of Variables To Help Predict Navigator Training Success And Classification, Gary A. Hagler
A Study Of Variables To Help Predict Navigator Training Success And Classification, Gary A. Hagler
Theses and Dissertations
This study attempted to build statistical models which could possibly be used to help predict an individual's final outcome of pass or fail from Undergraduate Navigator Training (UNT). Also, the research tried to develop models to help place a potential trainee into one of the three training tracks at UNT. The variables studied were test scores from a computerized testing device which measured psychomotor and cognitive skills of individuals entering training. The Air Force Officers Qualifying Test (AFOQT) scores were also variables considered. Data was from 317 trainees from the years 1988 to 1990. Discriminant analysis was applied in an …
A Solution Methodology For The Variable-Level Scheduling Problem, Dennis R. Benson
A Solution Methodology For The Variable-Level Scheduling Problem, Dennis R. Benson
Theses and Dissertations
This study looked at a specific scheduling problem for a Department of Defense agency. A heuristic algorithms was developed to solve a general variable-level scheduling problem and was applied to this specific problem. This heuristic used linear programming and integer programming to find the minimum number of weekly billable hours for five alternative schedules. The best alternative schedule was further developed into a spreadsheet designed, squad level, master schedule. The result of this study was a proposed schedule that would save the United States government 8.2% of their security costs for this one part of the governmental agency. These savings …
The Utility Of Elliptical And Circular Confidence Regions For Hfdf Receivers, Paul T. Nemec
The Utility Of Elliptical And Circular Confidence Regions For Hfdf Receivers, Paul T. Nemec
Theses and Dissertations
This thesis investigates HFDF confidence region (CR) shape exhibited by geolocations in a search-and-rescue context. In Phase I, a Keeney-Raiffa multiattribute utility function was developed which allowed an analytical measure of preference between elliptical and equivalent- probability circular CRs. Phase II utilized a likelihood approach to establish CR shape for sample operational geolocations having multiple points of bearing intersections. For 12 sample Phase I geolocations, the elliptical CR always had higher utility than its corresponding circular CR. For accepted sample geolocations, a preference condition was developed whereby a circular CR would only be preferred over the corresponding elliptical CR if …
Multicriteria Network Routing Of Tactical Aircraft In A Threat Radar Environment, Ernst K. Isensee
Multicriteria Network Routing Of Tactical Aircraft In A Threat Radar Environment, Ernst K. Isensee
Theses and Dissertations
Real-time route planning for tactical aircraft has established a requirement for analytical tools which prescribe optimal solutions. The Air Force Electronic Warfare Center has developed a computerized routing aid which enhances the ability to plan tactical flight missions under real-time constraints. The decision aid known as the Improved Many-on-Many (IMOM) allows the user to subjectively evaluate flight routes within enemy radar coverages. However, the mission planner is required to intuitively assesses the survivability risks associated for each user defined route. As an alternative to this method, the deterministic procedures of dynamic programming and the shortest path algorithms offer techniques which …
Incorporating Value Systems In Strategic Force Analysis, Nancy D. Snyder
Incorporating Value Systems In Strategic Force Analysis, Nancy D. Snyder
Theses and Dissertations
Deterring potential Soviet aggression depends on our ability to hold at risk those assets they value most. This research investigates target valuation as an added dimension to force structure analysis. An extensive literature review is followed by the development and demonstration of a methodology defining development and use target values. The literature review covers arms control concepts to give a foundation for an important use of force structure analysis. It also covers measures of effectiveness. The final part of the review is comprised of definitions of perspectives on nuclear war. The methodology defines motivations for force structuring in the form …
Effects Of Colocation And Non-Colocation Of Sensors And Actuators On Flexible Structures, W. C. Lee
Effects Of Colocation And Non-Colocation Of Sensors And Actuators On Flexible Structures, W. C. Lee
Theses and Dissertations
This thesis compares the performance and robustness of colocated and non-colocated sensor/actuator pairs. Linear quadratic Gaussian and loop transfer recovery (LOG/LTR) procedures are used to design optimum controllers for three example problems. The first example is a single motion degree-of-freedom system having motion only about one axis. This type of system does not have any right half plane zeros for the non-colocated case; however, the thesis shows it behaves as a non minimum phase system. The second example is a Bernoulli-Euler beam which does not have RHP zeros. An optimum LOG/LTR controller can not improve the robustness of non minimum …
A Prolog-Based System For Hardware Verification, Kevin L. Sparks
A Prolog-Based System For Hardware Verification, Kevin L. Sparks
Theses and Dissertations
With the expanding number of components provided on a single digital chip, verification of digital designs is becoming a major problem. The more circuits one places on a single chip, the greater the number of input/output combinations which need to be checked. A paper by Barrow in 1984 discusses a Prolog-based hierarchical formal verification system which he calls VERIFY. Barrow provided a lot of information on what VERIFY can and cannot do, and on projected enhancements. He does not, however, mention how VERIFY actually performs the task of formal verification. This thesis will provide a description of one possible implementation …
Sensitivity Analysis For The Selection Of Linear Quadratic Regulator Weighing Parameters Q And R For Active Vibration Suppression Of A Cantilevered Beam, Steven L. Story
Sensitivity Analysis For The Selection Of Linear Quadratic Regulator Weighing Parameters Q And R For Active Vibration Suppression Of A Cantilevered Beam, Steven L. Story
Theses and Dissertations
There has been much interest during the past decade to develop and launch large space structures. The high cost of launching material into orbit will require that these structures be assembled in space using light weight elements which are vulnerable to dynamic excitations. Active control may be necessary to rapidly attenuate large amplitude vibrations. The active vibration control system is usually designed after the structure has been optimized. The integrated design of the control system and the structure may provide additional weight savings. This thesis presents a sensitivity analysis of the structure/ control optimization problem. The structure used is an …
A Common Interface Real-Time Multiprocessor Operating System For Embedded Systems, Michael S. Rottman
A Common Interface Real-Time Multiprocessor Operating System For Embedded Systems, Michael S. Rottman
Theses and Dissertations
Large real time applications such as aerospace avionics systems, battle management, and factory automation place many demands and constraints on the computing system not found in other applications. Software development is hindered by software dependence on the computer architecture and the lack of portability between systems. This thesis specifies and designs a real time multiprocessor operating system (RTMOS) that implements a consistent programming model, enabling the development of real time parallel software independent of the target architecture. The RTMOS defines the core functionality required to demonstrate the programming model. The RTMOS functional requirements are specified using Structured Analysis and Design …
An Environmentally Controlled Chamber For The Study Of Radon Detection, William R. Wharton Jr.
An Environmentally Controlled Chamber For The Study Of Radon Detection, William R. Wharton Jr.
Theses and Dissertations
A system was developed to dynamically control and monitor the environment and radon concentration within a glovebox chamber for the study of radon. The system is designed around a personal computer workstation which automates the entire system. The radon concentration is determined by monitoring the count rate from radon and its progeny which are continuously circulated from the radon chamber through a Lucas Cell detection system. This information is then used as a base for controlling a radon injection system. When the concentration within the glovebox drops, the system injects a precisely-measured volume of high activity radon gas into the …
An Assessment Of The Accuracy Of Semi-Empirical Quantum Chemistry Calculations Of The Mechanical Properties Of Polymers, James R. Shoemaker
An Assessment Of The Accuracy Of Semi-Empirical Quantum Chemistry Calculations Of The Mechanical Properties Of Polymers, James R. Shoemaker
Theses and Dissertations
The ultimate mechanical properties of polymers, assuming perfect morphology, will be limited by the mechanical properties of a single, ideal polymer chain. Previous calculations of polymer chain moduli using semi- empirical (SE) quantum chemistry methods have resulted in modulus values much higher than experimentally measured. This study investigated the error in the calculated inherent to the method of calculation by comparing SE results for C-C bond potentials in two well characterized polymers, polyethylene and polydiacetylene. It was found that the SE calculation systematically overpredicted bond stiffness in these polymers by approximately 25% to 30%. This is the upper limit on …
Agility: Presentation And Flight Test Methods For The Operational Fighter Pilot, William R. Langdon
Agility: Presentation And Flight Test Methods For The Operational Fighter Pilot, William R. Langdon
Theses and Dissertations
This thesis develops both metrics and flight test techniques to measure agility. During development of both the agility metrics and the flight test techniques, previous work conducted by the agility community and the Flight Test Center at Edwards Air Force Base was used as a lessons learned tool to insure favorable results. Both simulator and flight testing was performed to validate the flight test techniques. During simulator testing several problems with the original flight test techniques were noted. Flight testing on the pitch agility flight test technique solved most of its problems but problems found during roll testing in the …
Optimal Iterative Task Scheduling For Parallel Simulations, Joann M. Sartor
Optimal Iterative Task Scheduling For Parallel Simulations, Joann M. Sartor
Theses and Dissertations
The ultimate purpose of this research is to reduce the time needed for execution of parallel computer simulations. In particular, the impact of task assignment strategies is determined for parallel VHDL circuit simulations. The classical scheduling problem, which assigns n precedence-constrained tasks to m processors is NP-complete in all but the simplest cases. The problem of assigning simulation tasks is further complicated by the iterative nature of computer simulations: each task is required to execute multiple times as the simulation executes. This investigation develops a polynomial-time algorithm (the level strategy) which provides optimal assignment for iterative systems with specific constraints. …
Construction, Calibration And Use Of A Neutron Time-Of-Flight Spectrometer, Charles L. Wood
Construction, Calibration And Use Of A Neutron Time-Of-Flight Spectrometer, Charles L. Wood
Theses and Dissertations
The energy spectrum of a 5 curie Pu-Be neutron source is determined by use of a neutron time-of-flight spectrometer. This spectrometer measures the time it takes for a neutron to travel between two plastic scintillator detectors. Using a fixed distance for travel, a time spectrum is generated which is then unfolded into the energy spectrum of the source. The different aspects of equipment selection, connection and calibration of the system are described. With the resolved spectrum the energy resolution of the spectrometer is determined by using a Monte Carlo simulation of the experimental set-up. A dual- parameter experiment is conducted …
Development Of An Angular Distribution Function For The Study Of Atomic Lattice Structures Used In Atomistic Simulation, David Wesley
Development Of An Angular Distribution Function For The Study Of Atomic Lattice Structures Used In Atomistic Simulation, David Wesley
Theses and Dissertations
An angular distribution function (ADF) was developed as a tool to be used in atom simulation. The ADF lets us easily distinguish between different lattice structures for systems of atoms by looking at the distribution of bond angles. The ADF is also a useful tool for determining the amount of order in a system. First, model structures of simple cubic, FCC, BCC, and diamond were developed. Then, the ADF was used on these model structures so that a set of model graphs of the ADF could be used to compare to real systems. Finally, simulated systems of Ferric Titanate, Nickel …