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Articles 5311 - 5340 of 5698
Full-Text Articles in Engineering
Development Of The Air Module For The Work Information Management System. Environmental Subsystem (Wims-Es), Robert A. Cantwell, Jonathan S. Davis
Development Of The Air Module For The Work Information Management System. Environmental Subsystem (Wims-Es), Robert A. Cantwell, Jonathan S. Davis
Theses and Dissertations
The primary objective of this research was to develop the air module for the Work Information Management System Environmental Subsystem (WIMSES). The air module will provide Air Force environmental managers with a management information system (MIS) to control the growing amount of air pollution data required to stay in compliance with the newly amended Clean Air Act. To develop the air module, the Air Force's air pollution management requirements were researched first. These requirements were then compared to the capabilities of existing air pollution MISs used in the Department of Defense, the Environmental Protection Agency, and in commercial industry. The …
A Model Action Plan To Reduce The Use And Release Of Cfcs In Air- Conditioning And Refrigeration Systems, David W. Andrews, Daniel P. Ellert-Beck
A Model Action Plan To Reduce The Use And Release Of Cfcs In Air- Conditioning And Refrigeration Systems, David W. Andrews, Daniel P. Ellert-Beck
Theses and Dissertations
This study investigated methods to reduce the use and release of chlorofluorocarbon (CFC) refrigerants and evaluated alternatives to CFCS in air- conditioning and refrigeration systems. A life cycle cost (LCC) analysis formed the basis for evaluation. A literature review examined applicable CFC directives, containment methods, replacement refrigerants, and alternative processes. The results of the LCC analysis showed that maintaining the existing CFC system was always the least costly alternative. When forced to replace a CFC reciprocating package unit, the best replacement was a non-CFC reciprocating unit. The most practical replacement for reciprocating chillers was a new reciprocating chiller for systems …
A Study In Use And Management Of De/Anti-Icing Constituents With Regard To New Storm Water Legislation, Darren P. Gibbs, Bruce L. Willing
A Study In Use And Management Of De/Anti-Icing Constituents With Regard To New Storm Water Legislation, Darren P. Gibbs, Bruce L. Willing
Theses and Dissertations
This research identified management practices of airfield and aircraft de/anti-icing constituents which may be implemented to deal with new storm water legislation. Storm water regulations require that deicing operations obtain a NPDES permit for discharges into storm water runoff which may mandate the use of Best Management Practices. An FAA civilian airport survey and a USAF survey were used, with a literature search, to identify practices of de/anti- icing constituents. Four major constituents are used-glycol, urea, calcium magnesium acetate, and sodium formate. Concerns of uncontrolled release of the constituents include high BOD rates, nitrate and nitrite enrichment, impaired aesthetic water …
A Comparison Of Aircraft Maintenance Organizational Structures, Wesley C. Davis, Sanford Walker
A Comparison Of Aircraft Maintenance Organizational Structures, Wesley C. Davis, Sanford Walker
Theses and Dissertations
This study compares the aircraft maintenance structure being implemented by General Merrill A. McPeak with that of the previous structure typified by TACR 66-5. Historical aircraft data is used to compare organizational structures. Data from the USAF and USN is used to build regression models to determine if organizational structure contributes to combat capability. Statistical tests are used to determine if a significant difference exists between the two organizational structures. Regression analysis and comparison of the results lead the researchers to conclude that a significant difference exists in the performance measures of COMO and Objective Wing organizations. While many reasons …
Change In Self-Efficacy As A Measure Of Training Effectiveness At Squadron Officer School, Edward J. Berghorn, Michael Lewis
Change In Self-Efficacy As A Measure Of Training Effectiveness At Squadron Officer School, Edward J. Berghorn, Michael Lewis
Theses and Dissertations
The purpose of this research was to determine the effect of the US air Force Squadron Officer School (SOS) training curriculum by measuring students' self-efficacy before and after training. The authors verified through the literature that an individual's personal assessment of his self-efficacy was associated with task understanding and performance. Then self-efficacy questions were generated (for each of the four SOS curriculum areas) for an individual to assess his ability to perform a behavior related to a particular SOS learning objective. Demographic questions were also developed and combined with the self- efficacy questions to form pretest (before SOS training) and …
Pollution Prevention, An Investment Decision Model To Assess Financial Feasibility For Application To Air Force Processes, Debra S. Rankin, Clare R. Mendelsohn
Pollution Prevention, An Investment Decision Model To Assess Financial Feasibility For Application To Air Force Processes, Debra S. Rankin, Clare R. Mendelsohn
Theses and Dissertations
This research develops a Pollution Prevention Investment Decision Model (PPIDM) to evaluate the financial feasibility of pollution prevention alternatives. The PPIDM provides managers with simple, systematic, and flexible guidelines for making accurate and expedient decisions when considering pollution prevention alternatives. The model illustrates that a comprehensive analysis is not always necessary. The PPIDM gives managers the flexibility to adjust the economic feasibility criteria based on top management's perceptions of the political environment. When top management places a very high value on political considerations, economic criteria is insignificant and the project may be implemented immediately without further analysis. The PPIDM takes …
Development And Application Of A Methodology For Evaluating Type Ii Expired Shelf Life Hazardous Material Generation In The United States Air Force, Jennifer Putz
Theses and Dissertations
The Pollution Prevention Act of 1990, Air Force Directive 19-4, and the Air Force Pollution Prevention Plan require installations to reduce the amounts of hazardous waste generated. To meet the requirements set forth in these documents, each waste stream containing a hazardous waste needs to be identified and characterized for changes in policies or procedures that would reduce the hazardous waste generated. This research develops a methodology to determine the amount of materials with a type II shelf life that is disposed of as hazardous waste because the shelf life expired while the material was in base supply storage. This …
A Study Of Configuration Management At Headquarters Logistics Command (Royal Australian Air Force), John F. Turner
A Study Of Configuration Management At Headquarters Logistics Command (Royal Australian Air Force), John F. Turner
Theses and Dissertations
The purpose of this research was to provide insight into configuration management at the Royal Australian Air Force's Headquarters Logistics Command (HQLC) by determining whether current configuration management practices have any impact on HQLC's ability to meet its mission of providing logistics support. The research begins with a review of RAAF configuration management policy and procedures as applicable to in-service systems or technical equipment. A case study is used to investigate problems associated with inadequate configuration management being experienced by one HQLC engineering section, and to identify subsequent effects on engineering logistics capability. The case study results are used to …
Autonomous Face Segmentation, Kevin P. Gay
Autonomous Face Segmentation, Kevin P. Gay
Theses and Dissertations
The purpose of this study was to implement an autonomous face segmentor as the front end to a face recognition system on a Sun SPARCStation2. Face recognition performance criteria, specifically, the capabilities to isolate and resize faces in an image to a consistent scale, were analyzed to determine current practical limitations. Face images were acquired using a S-VHS camcorder. Segmentation was accomplished using motion detection and predefined rules. Tests were run to determine the suitable of the autonomous segmentor as the front-end to a face recognition system. The segmentation system developed consistently located faces and rescaled those faces to a …
Multi-Ion Ambipolar Diffusion, Thomas E. Gist
Multi-Ion Ambipolar Diffusion, Thomas E. Gist
Theses and Dissertations
The continuity and momentum equations for electrons and multiple ion species are solved analytically and numerically using a new model for ambipolar diffusion. The general form of the model is valid for any quasi-neutral plasma for which the diffusion approximation is appropriate, including positive or negative ions, arbitrary geometries, and time dependence. The model provides criteria for determining when single ion diffusion theory is appropriate for describing multi-ion discharges, when a multi-ion proportional model is appropriate, and when a multi-ion nonproportional model is necessary. An expression is developed which provides a necessary condition for proportionality and provides the proportionality constant …
Development Of An Analog Mimo Quantitative Feedback Theory (Qft) Cad Package, Richard R. Sating
Development Of An Analog Mimo Quantitative Feedback Theory (Qft) Cad Package, Richard R. Sating
Theses and Dissertations
This thesis describes the development of an analog MIMO Quantitative Feedback Theory (QFT) CAD package for the automation of the multivariable control design process. The CAD package is capable of carrying a design from problem setup through the design process to a frequency domain analysis of the compensated MIMO system. The package automates the selection of the weighting matrix, formation of the square effective plants, the polynomial matrix inverse required to form the equivalent plants, generation of stability, tracking, disturbance, gamma, and composite bounds, loop shaping, design of the prefilter elements, and the frequency domain analysis of the completed design. …
Neutron Fluence And Dose From A Varian Clinic 1800 Accelerator, Richard A. Jackson
Neutron Fluence And Dose From A Varian Clinic 1800 Accelerator, Richard A. Jackson
Theses and Dissertations
The goals of this study were (1) to verify calibration factors determined by previous experiment for relating counts from activated gold foils to neutron fluences, and (2) to use the method to determine neutron fluences under various operating conditions of the Varian Clinac 1800 (18-MeV) electron accelerator at the WPAFB Medical Center. For comparison similar measurements were made of the CGM Saturne 1 at Kettering Memorial Hospital, Dayton, Ohio. Cadmium-difference pairs in a standard graphite pile were employed to verify the counting efficiency of the Geiger-Mueller beta counting system used to count the foil activity. They were also used to …
Multiple Model Adaptive Estimation Applied To The Vista F-16 With Actuator And Sensor Failures, Timothy E. Menke
Multiple Model Adaptive Estimation Applied To The Vista F-16 With Actuator And Sensor Failures, Timothy E. Menke
Theses and Dissertations
A Multiple Model Adaptive Estimation (MMAE) algorithm is applied to the Variable Stability In-flight Simulator Test Aircraft (VISTA) F-16 at a low dynamic pressure flight condition (0.4 Mach at 20000 ft). A complete F-16 flight control system is modeled containing the longitudinal and lateral-directional axes. Single and dual actuator and sensor failures are simulated including: complete actuator failures, partial actuator failures, complete sensor failures, increased sensor noise, sensor biases, dual complete actuator failures, dual complete sensor failures, and combinations of actuator and sensor failures. Failure scenarios are examined in both maneuvering and straight and level flight conditions. The system performance …
A Modal Analysis And Modelling Of A Lightly Damped Large Space Structure, Scott E. George
A Modal Analysis And Modelling Of A Lightly Damped Large Space Structure, Scott E. George
Theses and Dissertations
This study involves the modification to the PACOSS Dynamic Test Article to create a lightly damped representative large space structure with closely spaced, low frequency modes. An experimental modal analysis is performed to recharacterize the low frequency flexible vibration modes. A finite element model is created using MSC/NASTRAN to predict low frequency behavior using both real eigenvalue analysis and frequency response analysis. Then a reduced order model is created and fine-tuned to represent the dynamics of the structure for the identified low frequency modes.
A Method For Determining Schedule Delay Information In A Channel Cargo Route Network Schedule, Justin E. Moul
A Method For Determining Schedule Delay Information In A Channel Cargo Route Network Schedule, Justin E. Moul
Theses and Dissertations
This research develops a method for measuring schedule effectiveness by determining the amounts of enroute, cargo delay caused by a given aircraft mission schedule. The method is designed to generate information which helps identify flights for which different scheduling might decrease overall cargo delay in the entire network, given that all non-scheduling factors are held constant. The research uses a simplified twelve-airport cargo route network to test the methodology.
Wing Rock Prediction Method For A High Performance Fighter Aircraft, Robert C. Nolan Ii
Wing Rock Prediction Method For A High Performance Fighter Aircraft, Robert C. Nolan Ii
Theses and Dissertations
This study is a limited investigation of the nonlinear aircraft behavior known as wing rock. An eight state F-15 model is analyzed using bifurcation theory. The wing rock onset point is identified and small perturbation analysis is used to linearize the equations of motion about this point. The eigenstructure of the model is analyzed and is used to identify the stability modes involved in this motion. A procedure is developed to predict wing rock onset and frequency and the critical stability derivatives involved in this motion are identified. The developed procedure is applied to existing F-4J data and a flight …
Strategic Deterrence In The Post-Start Era, David C. Mccormick
Strategic Deterrence In The Post-Start Era, David C. Mccormick
Theses and Dissertations
With the Soviet Union's fall there have been widespread calls for drastic reductions in the United States military's strategic nuclear forces. Although a major threat to the United States has been greatly reduced, the number of strategic targets will not decrease as rapidly as the number of available weapons. This research considers how the United States should think about strategic forces in the rapidly changing world order of the 1990s. An extensive literature review of deterrence concepts and conventional weapons capabilities is conducted with special attention paid to the role that precision guided munitions played in the 1991 Persian Gulf …
Comparison Of Synchronization Techniques For The Afit Direct Sequence Spread Spectrum System, Edward A. Bednar
Comparison Of Synchronization Techniques For The Afit Direct Sequence Spread Spectrum System, Edward A. Bednar
Theses and Dissertations
The purpose of this study is to analyze and evaluate the performance of several code synchronization methods that could be used in the Air Force Institute of Technology's (AFIT) Direct-Sequence Spread Spectrum (DSSS) communication system. These methods include the sliding correlator, transmitted reference, sequential estimation, and three types of matched filters. The matched filters are the baseband matched filter, delay line matched filter, and the convolver. The criteria used for the evaluation of these synchronization methods are theoretical synchronization times and probability of bit-error. Advantages and disadvantages of each synchronization method are described and a method is recommended to be …
Experimental Evaluation Of Incorporating Digital And Analog Integrated Circuit Die On A Common Substrate Utilizing Silicon-Hybrid Wafer-Scale Integration Technology, Philip C. Reamy
Theses and Dissertations
The objective of this research effort was to investigate the implementation of analog circuits in a wafer scale integration system. A test circuit composed of analog and digital subsystems was designed and tested through simulation. IC die containing this test circuit were utilized in the WSI system fabrication. Preliminary investigations were conducted to evaluate the potential improvements to the IC die mounting procedure, a key step in fabricating functional WSI systems. These investigations demonstrated a procedure which produced repeatable results in achieving acceptable planarization of IC die and host substrate surfaces. These investigations also demonstrated the successful application of a …
Development Of A Stratified Plate Model For Composite Panels, Alan L. Lesmerises
Development Of A Stratified Plate Model For Composite Panels, Alan L. Lesmerises
Theses and Dissertations
A new model for composites represents a composite panel as an alternating stack of isotropic matrix and orthotropic fiber-dominated layers. An energy approach results in a set of partial differential equations and boundary conditions where the mechanical properties of the matrix and fibers appear separately. Two solution methods are developed. The first, called Strata Theory is developed for general applications, while the second, called the Exact Stratified Plate, is used as a benchmark for comparison to Strata Theory. Both solutions assume zero gradients of displacement through the thickness of a fiber layer. They are compared for an isotropic material and …
Effects Of Facility Configurations And Scheduling Techniques On Aircraft Throughput For Warner Robins Alc Paint/Depaint Facilities, David V. Mcelveen
Effects Of Facility Configurations And Scheduling Techniques On Aircraft Throughput For Warner Robins Alc Paint/Depaint Facilities, David V. Mcelveen
Theses and Dissertations
The purpose of this research was to determine the effects of configuration options and dispatching rules on aircraft throughput for the WR- ALC paint/depaint facilities. A simulation model was constructed and used for this analysis as the primary means to conduct the research. The dispatching rules considered were first come first served, largest number in queue, shortest processing time, and a look ahead heuristic. Due to a reduction in the number of paint aircraft, no configuration option differing from the baseline significantly affected aircraft throughput. Dispatching rules were also found to produce no significant differences on aircraft throughput. Configuration options …
Quantifying The Impact Of The Acquisition Professional Development Program Certification Requirements On The Air Force Institute Of Technology, Paul A. Nicholson
Quantifying The Impact Of The Acquisition Professional Development Program Certification Requirements On The Air Force Institute Of Technology, Paul A. Nicholson
Theses and Dissertations
The purpose of this research is to determine the impact of implementing the Acquisition Professional Development Program on the Air Force Institute of Technology. APDP is part of a DOD-wide effort to decrease inefficiency in the procurement process. The program encompasses a tri-level certification process based on experience, training, and educational standards. APDP serves as a guideline for professional development of acquisition personnel from entry to senior level management. Many of the courses required for certification are offered through AFIT School of Systems and Logistics. Integrating the new educational requirements as a standard for career development is expected to produce …
An Analysis Of Escort Formations, Mustafa Ilhan
An Analysis Of Escort Formations, Mustafa Ilhan
Theses and Dissertations
This study used computer simulation to investigate escort fighter formations unknown interceptor threat environment. A USAF computer simulation model, TAC, was used to simulate air combat between the escorts and the interceptors in several different combat scenarios. The escort formations were defined by the vertical and horizontal distances of the escort fighters from the main strike body. Interceptors were characterized as one of two types of fighters with dissimilar aircraft frames and missile firing ranges. A central composite design was used to mathematically model the effect of escort formations and interceptor type on the survivability of the bombers and escorts. …
An Improved Scheduling Algorithm For Eglin Afb Test Ranges, Jeffrey S. Antes
An Improved Scheduling Algorithm For Eglin Afb Test Ranges, Jeffrey S. Antes
Theses and Dissertations
This research develops an algorithm that integrates into an existing computerized scheduling system to improve the mission scheduling function for Eglin AFB test ranges. The primary objective of this research was to design an improved computerized scheduling aid. The measure of performance for this approach is the number of missions scheduled using this aid as compared to current Eglin capabilities. Constructive heuristics are used in the algorithm to schedule missions according to critical resource groups while ensuring mission priority is not violated. The success of this new interactive scheduling algorithm is measured against a schedule produced by the current computer …
A Decision-Theoretic Approach To Recommending Action In The Air-To- Ground Aircraft Of The Future, Garrison H. Flemings
A Decision-Theoretic Approach To Recommending Action In The Air-To- Ground Aircraft Of The Future, Garrison H. Flemings
Theses and Dissertations
Designers of air-to-ground fighters of the future should consider including decision support systems to relieve pilots of some of the present workload. Those decision support systems should use utility theory. This work reviews two techniques of utility theory (decision trees and influence diagrams) and a new technique due to Morlan (probability ratio nets). The work includes a proposed structure for action recommendation systems in air-to-ground fighters of the future. The work describes an implementation of probability ratio nets. The work demonstrates the value of decision theory to air-to-ground fighters of the future by way of solving an example problem and …
A Response Surface Methodology Study Of Ferroelectric Memory Devices, Kevin C. Smith
A Response Surface Methodology Study Of Ferroelectric Memory Devices, Kevin C. Smith
Theses and Dissertations
Fatigue in ferroelectric memory devices was studied. The application of fatigue pulses to a ferroelectric sample was controlled by the RT-66 Ferroelectric Tester, a variation of the Sawyer-Tower circuit. The RT-66 also controlled data collection following the fatiguing process. Seven variables were evaluated for their potential- affect on fatigue. A sequence of fatigue tests, which varied the settings of these variables, was developed using Response Surface Methodology (RSM) experimental designs. Least-squares regression models were developed once a particular RSM set of design experiments was completed. These models were evaluated using RSM tools, and the analysis of these models allowed the …
A Sensitivity Analysis Of Circular Error Probable Approximation Techniques, Peter Puhek
A Sensitivity Analysis Of Circular Error Probable Approximation Techniques, Peter Puhek
Theses and Dissertations
Several algebraic CEP estimates models were examined in this study. Each assumes that the crossrange and downrange miss distances of the sample data follow a bivariate normal distribution. The analysis determined the sensitivities of these models to changes in the parameters of sample size, bias, correlation, and ellipticity. The accuracy of each model is expressed in terms of relative error, and the parameter regions in which a certain method dominated as the most accurate were noted. In general, it was found that bias was the most significant parameter in determining the best CEP method. A simple method, based on the …
Implementation And Analysis Of Np-Complete Algorithms On A Distributed Memory Computer, Joel S. Garmon
Implementation And Analysis Of Np-Complete Algorithms On A Distributed Memory Computer, Joel S. Garmon
Theses and Dissertations
The purpose of this research is to explore methods used to parallelize NP-complete problems and the degree of improvement that can be realized using different methods of load balancing. A serial and four parallel A* branch and bound algorithms were implemented and executed on an Intel iPSC/2 hypercube computer. One parallel algorithm used a global, or centralized, list to store unfinished work and the other three parallel algorithms used a distributed list to store unfinished work locally on each processor. the three distributed list algorithms are: without load balancing, with load balancing, and with load balancing and work distribution. The …
Development Of A System For Survey Of Radon Concentration Of The Dayton Area Using A Liquid Scintillation Counter And Analysis Of The Data, Taewon Kim
Theses and Dissertations
A system to do a large scale survey was developed. The data obtained from the survey was analyzed using a database. The database incorporated an equation for converting cpm into radon concentration pCi/ℓ). The equation of conversion, protocol for measuring radon concentration, survey form, and a database program were modified (from previous theses) or developed for this thesis. The elution time constant, adsorption time constant, and calibration factor were calculated for equation of conversion. Two surveys were during the course of the thesis. On the first survey, the arithmetic average radon concentration with standard error of the mean was 2.9 …
Model Of A Nuclear Thermal Test Pipe Using Athena, Mark J. Dibben
Model Of A Nuclear Thermal Test Pipe Using Athena, Mark J. Dibben
Theses and Dissertations
Nuclear thermal propulsion offers significant improvements in rocket engine specific impulse over rockets employing chemical propulsion. The computer code ATHENA (Advanced Thermal Hydraulic Energy Network Analyzer) was used in a parametric analysis of fuelpipe. The fuelpipe is an annular particle bed fuel element of the reactor with radially inward flow of hydrogen through it. The outlet temperature of the hydrogen is parametrically related to key effects, including the effect of reactor power at two different pressure drops, the effect of the power coupling factor of the Annular Core Research Reactor, and the effect of hydrogen flow. Results show that the …