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2002

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Articles 991 - 1020 of 1792

Full-Text Articles in Engineering

Periodic Methods For Controlling A Satellite In Formation, Erin Y. Carraher Mar 2002

Periodic Methods For Controlling A Satellite In Formation, Erin Y. Carraher

Theses and Dissertations

Precise position determination and control is necessary to accomplish proposed satellite formation flying missions of ground movement target indication and synthetic aperture radar. This thesis combines the estimation and control techniques of past AFIT theses with various time-varying and time-invariant LQG control methods. Linear time-invariant control is ideal for on-board satellite estimation and control applications, freeing-up the satellite's limited computational capacity. Using a dynamics frame transformation from the nodal frame to an orbital frame, a higher fidelity, time-periodic model produced nearly identical results for either time-varying or time-invariant control for many scenarios. Scenarios included initial perturbations in the radial, in-track, …

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Beyond A-76: How To Achieve The Goals Without The Pain, Kurt A. Chelf Mar 2002

Beyond A-76: How To Achieve The Goals Without The Pain, Kurt A. Chelf

Theses and Dissertations

The Department of Defense has determined that Outsourcing and Privatization is key to reducing operating costs and subsequently providing the fiscal dollars necessary to modernize the U.S. Armed Forces. In an effort to achieve this goal, the DoD has mandated that the Air Force study at least 5% of its manning positions for possible conversion to contract. This mandate effects over 200,000 positions throughout the department. Office of Management and Budget (OMB) Circular, Number A-76, Performance Of Commercial Activities dictates the process used to study the appropriateness of these conversions. This thesis explores the usefulness and applicability of this process, …

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Task Load And Automation Use In An Uncertain Environment, Mark A. Daly Mar 2002

Task Load And Automation Use In An Uncertain Environment, Mark A. Daly

Theses and Dissertations

The purpose of this research was to investigate the effects that user task load level has on the relationship between an individual's trust in and subsequent use of a system's automation. Automation research has demonstrated a positive correlation between an individual's trust in and subsequent use of the automation. Military decision-makers trust and use information system automation to make many tactical judgments and decisions. In situations of information uncertainty (information warfare environments), decision-makers must remain aware of information reliability issues and temperate their use of system automation if necessary. An individual's task load may have an effect on his use …

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An Analysis Of The Knowledge And Skill Levels Required To Effectively Support Analytical Cost Decisions In Source Selections, Anthony L. Smith Mar 2002

An Analysis Of The Knowledge And Skill Levels Required To Effectively Support Analytical Cost Decisions In Source Selections, Anthony L. Smith

Theses and Dissertations

We analyze these three factors (education, experience, and training) in an effort to identify the knowledge and skills necessary for cost analysts to possess to be effective members of cost panel evaluation teams during source selections. This research effort assesses whether the cost panel members and senior Air Force acquisition military and civilian personnel associate the levels of education, experience, and training as being key factors in fulfilling cost analysts duties while supporting the selection of a source in the government procurement process. To accomplish this objective, a literature review, personal interviews, and questionnaires were utilized. Descriptive statistics and hypothesis …

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A Collaborative Visualization Framework Using Jini™ Technology, Chad M. Harris Mar 2002

A Collaborative Visualization Framework Using Jini™ Technology, Chad M. Harris

Theses and Dissertations

It is difficult to achieve mutual understanding of complex information between individuals that are separated geographically. Two well-known techniques commonly used to deal with this difficultly are collaboration and information visualization. This thesis develops a generic flexible framework that supports both collaboration and information visualization. It introduces the Collaborative Visualization Environment (COVE) framework, which simplifies the development of real-time synchronous multi-user applications by decoupling the elements of collaboration from the application. This allows developers to focus on building applications and leave the difficulties of collaboration (i.e., concurrency controls, user awareness, session management, etc.) to the framework. The framework uses an …

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Smart Structures For Control Of Optical Surfaces, D. Michael Sobers Jr. Mar 2002

Smart Structures For Control Of Optical Surfaces, D. Michael Sobers Jr.

Theses and Dissertations

The development of lightweight, large-aperture optics is of vital importance to the Department of Defense and the US Air Force for advancing remote sensing applications and improving current capabilities. Synthetic polymer optics offer weight and flexibility advantages over current generation glass mirrors, but require active control to maintain tight surface figure tolerances. This research explores the feasibility of using imbedded piezoelectric materials to control optical surfaces. Membrane-based and stiff piezo-controlled mirrors were constructed to develop and validate control techniques. Test results verified that surface control on the order of tens of wavelengths is possible using these systems.

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Evaluating Air Force Civil Engineer's Current Automated Information Systems, Edward P. Phillips Mar 2002

Evaluating Air Force Civil Engineer's Current Automated Information Systems, Edward P. Phillips

Theses and Dissertations

Almost every organization has some form of information system where data is captured and stored for later use. The Air Force civil engineering organization is no exception and is in the process of transitioning from the Interim Work Information Management System (WIMS) to the Automated Civil Engineer System (ACES). This research focused on users perceptions of both database and data importance to determine if significant differences existed between various user sub-groups. The research also attempted to identify the most frequently reported problems regarding system usage. The methods of analysis of variance and content analysis were used to answer the research …

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An Analysis Of Horizontal Flow Treatment Well Applicability For The Treatment Of Chlorinated Solvent Contaminated Groundwater At United States Forces Korea Installations, Michael R. Staples Mar 2002

An Analysis Of Horizontal Flow Treatment Well Applicability For The Treatment Of Chlorinated Solvent Contaminated Groundwater At United States Forces Korea Installations, Michael R. Staples

Theses and Dissertations

Past research has shown that there is a rising public concern with environmental issues in the Republic of Korea (ROK). As Korean government and public interest in the environment grow, there is likely to be increased pressure to remediate environmental contamination at United States Department of Defense (DoD) installations in Korea. Impacting DoD's ability to remediate contaminated sites overseas is the fact that limited environmental funds must compete with high priority mission requirements. Thus, particularly at overseas bases, there is an urgent need for inexpensive and effective groundwater remediation technologies. Horizontal Flow Treatment Well (HFTW) systems have been demonstrated in …

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Evaluation Of Civil Engineering Operations Flight Competitive Sourcing Standards And Metrics, Ty A. Randall Mar 2002

Evaluation Of Civil Engineering Operations Flight Competitive Sourcing Standards And Metrics, Ty A. Randall

Theses and Dissertations

The Performance Work Statement (PWS), which defines the requirements and shapes the outcome of the activity under contract, and the Quality Assurance Surveillance Plan (QASP), which is vital in identifying what is to be evaluated, become critical documents as the Air Force enters into more competitive sourcing contracts. Currently, contractors and Most Efficient Organizations (MEO) are evaluated by the QASP based upon the requirements found in the PWS. It is imperative the PWS and QASP documents have adequate performance metrics and that they are applied appropriately to evaluate the contractor or MEO. This research collected PWS and QASP documents from …

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Comparative Energy And Cost Analysis Between Conventional Hvac Systems And Geothermal Heat Pump Systems, David D. Vanderburg Mar 2002

Comparative Energy And Cost Analysis Between Conventional Hvac Systems And Geothermal Heat Pump Systems, David D. Vanderburg

Theses and Dissertations

To sustain the United States current affluence and strength, the U.S. Government has encouraged energy conservation through executive orders, federal and local laws, and consumer education. A substantial reduction in U.S. energy consumption could be realized by using geothermal heat pumps to heat and cool buildings throughout the U.S., though initial installation cost are a deterrent. This thesis uses Monte Carlo simulation to predict energy consumption, life cycle cost and payback period for the vertical closed-loop ground source heat pump (GSHP) relative to conventional heating ventilation and air conditioning (HVAC) systems: air-source heat pumps (ASHP), air-cooled air conditioning with either …

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Empirical Analysis Of Various Multi-Dimensional Knapsack Heuristics, Yong Kun Cho Mar 2002

Empirical Analysis Of Various Multi-Dimensional Knapsack Heuristics, Yong Kun Cho

Theses and Dissertations

Since the multidimensional knapsack problems are NP-hard problems, the exact solutions of knapsack problems often need excessive computing time and storage space. Thus, heuristic approaches are more practical for multidimensional knapsack problems as problems get large. This thesis presents the results of an empirical study of the performance of heuristic solution procedures based on the coefficients correlation structures and constraint slackness settings. In this thesis, the three representative greedy heuristics, Toyoda, Senju and Toyoda, and Loulou and Michaelides’ methods, are studied. The purpose of this research is to explore which heuristic of the three representative greedy heuristics performs best under …

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Statistical Error Analysis Of A Doa Estimator For A Pcl System Using The Cramer-Rao Bound Theorem, Kerim Say Mar 2002

Statistical Error Analysis Of A Doa Estimator For A Pcl System Using The Cramer-Rao Bound Theorem, Kerim Say

Theses and Dissertations

Direction of Arrival (DOA) estimation of signals has been a popular research area in Signal Processing. DOA estimation also has a significant role in the object location process of Passive Coherent Location (PCL) systems. PCL systems have been in open literature since 1986 and their applications are not as clearly understood as the DOA estimation problem. However, they are the focus of many current research efforts and show much promise. The purpose of this research is to analyze the DOA estimation errors in a PCL system. The performance of DOA estimators is studied using the Cramer-Rao Bound (CRB) Theorem. The …

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Determination Of The Possible Locations Of The Receiver On A Passive Coherent Location System, Considering The Effects Of The Terrain And The Atmospheric Conditions, Carlos A. Meier Mar 2002

Determination Of The Possible Locations Of The Receiver On A Passive Coherent Location System, Considering The Effects Of The Terrain And The Atmospheric Conditions, Carlos A. Meier

Theses and Dissertations

It has always been an issue for an armed force, or government, to obtain complete radar coverage over an area of interest. Generally, this objective remains unaccomplished due to geographical, technical, and/or operational reasons (meaning topographic obstacles, transmitted power, extreme isolation, hierarchy of objectives, etc.) The fact of having vast areas of territory beyond radar coverage can be decisive in an armed conflict. With the recent resurgence of bistatic radar theory and applications, now in the form of Passive Coherent Location (PCL) systems, using existing signal sources (TC and Radio Stations) it is possible to decrease the blind zones of …

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The Analysis Of Sophisticated Direction Of Arrival Estimation Methods In Passive Coherent Locators, Ahmet Ozcetin Mar 2002

The Analysis Of Sophisticated Direction Of Arrival Estimation Methods In Passive Coherent Locators, Ahmet Ozcetin

Theses and Dissertations

In passive coherent locators (PCL) systems, noise and the precision of direction of arrival (DOA) estimation are key issues. This thesis addresses the implementation of sophisticated DOA estimation methods, in particular the multiple signal classification (MUSIC) algorithm, the conventional beam forming (CBF) algorithm, and the algebraic constant modulus algorithm (ACMA). The goal is to compare the ACMA to the MUSIC, and CBF algorithms for application to PCL. The results and analysis presented here support the use of constant modulus information, where available, as an important addition to DOA estimation. The ACMA offers many simple solutions to noise and separation related …

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Flight Control Failure Detection And Control Redistribution Using Multiple Model Adaptive Estimation With Filter Spawning, Michael L. Torres Jr. Mar 2002

Flight Control Failure Detection And Control Redistribution Using Multiple Model Adaptive Estimation With Filter Spawning, Michael L. Torres Jr.

Theses and Dissertations

In the current research, the MMAE with Filter Spawning and Control Redistribution (MMAE/FS/CR) are used together to identify failures and apply appropriate corrections. This effort explores the performance of the MMAE/FS/CR in different regions of the flight envelope using model and gain scheduling. The MMAE/FS/CR is able to detect complete and partial actuator/surface failures, as well as complete sensor failures. Once the actuator/surface failure is identified and the effectiveness is determined in the case of partial failures, proper control is applied in order to accomplish the desired pilot command. Improvements in the algorithm are required in order to enhance the …

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Microdot - A Four-Bit Microcontroller Designed For Distributed Low-End Computing In Satellites, Anthony R. Woodcock Mar 2002

Microdot - A Four-Bit Microcontroller Designed For Distributed Low-End Computing In Satellites, Anthony R. Woodcock

Theses and Dissertations

Many satellites are an integrated collection of sensors and actuators that require dedicated real-time control. For single processor systems, additional sensors require an increase in computing power and speed to provide the multi-tasking capability needed to service each sensor. Faster processors cost more and consume more power, which taxes a satellite's power resources and may lead to shorter satellite lifetimes. An alternative design approach is a distributed network of small and low power microcontrollers designed for space that handle the computing requirements of each individual sensor and actuator. The design of microdot, a four-bit microcontroller for distributed low-end computing, is …

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A Direct Sequence Code-Division Multiple-Access Local Area Network Model, James R. Rapallo Jr. Mar 2002

A Direct Sequence Code-Division Multiple-Access Local Area Network Model, James R. Rapallo Jr.

Theses and Dissertations

The United States Air Force relies heavily on computer networks for every-day operations. The medium access control (MAC) protocol currently used by most local area (LAN) permits a single station to access the network at a time (e.g. CSMA/CD or Ethernet). This limits network throughput to, at most, the maximum transmission rate of a single node with overhead neglected. Significant delays are observed when a LAN is overloaded by multiple users attempting to access the common medium. In CSMA/CD, collisions are detected and the data sent by the nodes involved are delayed and transmitted at a later time. The retransmission …

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Evaluation And Mission-Specific Optimization Of Satellite Packet Telemetry Protocol For Use On Dod Flight Test Ranges, Beth A. Trapp Mar 2002

Evaluation And Mission-Specific Optimization Of Satellite Packet Telemetry Protocol For Use On Dod Flight Test Ranges, Beth A. Trapp

Theses and Dissertations

The DoD test range community has come to the realization that its telemetry abilities are obsolete. Efforts are therefore underway to improve telemetry systems at DoD test ranges. The overall objective of this project was to evaluate the practical use of the CCSDS packet telemetry protocol in DoD test ranges and determine the configuration that would maximize performance based on mission requirements. A secondary objective was to compare the CCSDS and ATM protocols in order to substantiate further exploration of using ATM in future DoD telemetry systems. Modeling and simulation of the CCSDS protocol showed a correlation between three CCSDS …

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Wavelet Domain Communication System (Wdcs): Packet-Based Wavelet Spectral Estimation And M-Ary Signaling, Marion Jay F. Lee Mar 2002

Wavelet Domain Communication System (Wdcs): Packet-Based Wavelet Spectral Estimation And M-Ary Signaling, Marion Jay F. Lee

Theses and Dissertations

A recently proposed Wavelet Domain Communication System (WDCS) using transform domain processing demonstrated excellent interference avoidance capability under adverse environmental conditions. This work extends previous results by: 1) incorporating a wavelet packet decomposition technique, 2) demonstrating M-Ary signaling capability, and 3) providing increased adaptivity over a larger class of interference signals. The newly proposed packet-based WDCS is modeled and its performance characterized using MATLAB®. In addition, the WDCS response to two scenarios simulating Doppler effects and physical separation of transceivers are obtained. The fundamental metric for analysis and performance evaluation is bit error rate (Pb). Relative to …

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An Analysis Of Airfield Throughput At Elmendorf Air Force Base Using The Airfield Simulation Tool, Andrew C. Jones Mar 2002

An Analysis Of Airfield Throughput At Elmendorf Air Force Base Using The Airfield Simulation Tool, Andrew C. Jones

Theses and Dissertations

This study sought to describe Turkish defense offsets in foreign procurements. Located at the epicenter of regions fraught with crisis, Turkey is a secular, democratic, liberal country sharing western moral values. With the tradition of its 1,000 years of statehood, its constitutional order, and its strong armed forces, Turkey is a center of power that can affect delicate balances of power in the region. Offsets started to become an important way of obtaining industrial and technological benefits when importing military equipment in the early and mid-1980s. Offset deals remain an important aspect of Turkish arms importing policy and offset applications …

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Comparative Analysis Of Leasing Versus Buying General Purpose Vehicles (Sedan) In The Korean Air Force, Jung J. Kim Mar 2002

Comparative Analysis Of Leasing Versus Buying General Purpose Vehicles (Sedan) In The Korean Air Force, Jung J. Kim

Theses and Dissertations

Elmendorf Air Force Base (AFB) is one of the two key ERS airfields for the Pacific Theater. The condition of en route airfields has recently come to the attention of the DoD and the GAO. Delays at these airfields may cause personnel and equipment to arrive late in theater. Fuel systems at Elmendorf AFB are currently being improved, but the GAO questions whether these improvements will help the throughput. As well as being an en route airfield, Elmendorf is also an important Interim Brigade Combat Team (IBCT) APOE for Fort Richardson. The IBCT is designed to operate in small-scale contingency …

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Characterization Of The Optical And Electrical Properties Of Proton-Irradiated 4h-Silicon Carbide, Heather C. Crockett Mar 2002

Characterization Of The Optical And Electrical Properties Of Proton-Irradiated 4h-Silicon Carbide, Heather C. Crockett

Theses and Dissertations

Epitaxial n-type 4H-silicon carbide (SiC) is irradiated with 2 MeV protons to evaluate the dislocation damage effects on the optical and electrical characteristics of the material. Semiconductor materials with a high tolerance to radiation fields have applications in several aerospace power and satellite systems. SiC is under investigation due to its potential for such space material applications. The optical properties of the material are investigated using temperature-dependent photoluminescence (PL) and the effects of proton irradiation on the electrical properties are evaluated using current-voltage measurements and constant-voltage deep level transient spectroscopy (CV-DLTS). Subsequent high-temperature thermal annealing and recovery of the irradiated …

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Selecting Salient Features In High Feature To Exemplar Ratio Conditions, Ismail Aslan Mar 2002

Selecting Salient Features In High Feature To Exemplar Ratio Conditions, Ismail Aslan

Theses and Dissertations

A key tenet to the Air Force's vision of Global Vigilance, Reach, and Power is the ability to project power via the use of aerial refueling. Scheduling of limited tanker resources is a major concern for Air Mobility Command (AMC). Currently the Combined Mating and Ranging Planning System (CMARPS) is used to plan aerial refueling operations, however due to the complex nature of the program and the length of time needed to run a scenario, the need for a simple tool that runs in much shorter time is desired. Ant colony algorithms are recently developed heuristics for finding solutions to …

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Identifying Enlisted Stay And Leave Population Characteristics With Discriminant Analysis, Zabrina Y. Hoggard Mar 2002

Identifying Enlisted Stay And Leave Population Characteristics With Discriminant Analysis, Zabrina Y. Hoggard

Theses and Dissertations

The research contribution of this thesis is the first known integrated architecture and feature selection algorithm for Radial Basis Neural Networks (RBNNs). The objective is to apply the network iteratively to determine the final architecture and feature set used to evaluate a problem. Additionally, this thesis compares three different classification techniques, Discriminant Analysis (DA), Feed-Forward Neural Networks (FFN) and RBNNs against several hard to solve problems. These problems were used to evaluate general classifier performance as well as the performance of the feature selection techniques. This thesis describes the classification techniques as well as the measures used to evaluate them. …

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An Integrated Architecture And Feature Selection Algorithm For Radial Basis Neural Networks, Timothy D. Flietstra Mar 2002

An Integrated Architecture And Feature Selection Algorithm For Radial Basis Neural Networks, Timothy D. Flietstra

Theses and Dissertations

There are two basic ways to control an Unmanned Combat Aerial Vehicle (UCAV) as it searches for targets: allow the UCAV to act autonomously or employ man-in-the-loop control. There are also two target sets of interest: fixed or mobile targets. This research focuses on UCAV-based targeting of mobile targets using man-in-the-loop control. In particular, the interest is in how levels of satellite signal latency or signal degradation affect the ability to accurately track, target, and attack mobile targets. This research establishes a weapon effectiveness model assessing targeting inaccuracies as a function of signal latency and/or signal degradation. The research involved …

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Modeling The Pre-Positioning Of Air Force Precision Guided Munitions, Daniel P. Johnstone Mar 2002

Modeling The Pre-Positioning Of Air Force Precision Guided Munitions, Daniel P. Johnstone

Theses and Dissertations

There exist factors that play a major role in an enlisted Airman's decision to either stay on active duty in the Air Force or separate. The current force structure of the U.S. Air Force and increased loss of enlisted personnel is a major concern as we look at maintaining manpower to meet the needs of the Air Force. The Air Force is reacting to this low retention problem by increasing the bonuses for initial enlistments and reenlistments, home basing, increasing quality of life for Air Force personnel with enlisted dormitory plus-ups, and under AEF personnel have increased predictability of deployment. …

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Robust Sensitivity Analysis For Multi-Attribute Deterministic Hierarchical Value Models, Yucel R. Kahraman Mar 2002

Robust Sensitivity Analysis For Multi-Attribute Deterministic Hierarchical Value Models, Yucel R. Kahraman

Theses and Dissertations

The Air Force's ability to deploy, employ, and sustain operations in forward locations is a key to mission success. An integral part of this strategy is equipment pre-positioning, to include: vehicles, aircraft support, consumable inventory, and munitions. This research focuses on defining and developing a model to aid decision makers with the afloat pre-positioning and deployment of munitions in an effort to ensure that the right weapons are available when, and where needed. This research places a particular focus on the strategic, global pre-positioning of the Afloat Pre-positioning Fleet (APF) in an effort to minimize the overall response time involved …

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Parameter Study For Optimizing The Mass Of A Space Nuclear Power System Radiation Shield, Benjamin R. Kowash Mar 2002

Parameter Study For Optimizing The Mass Of A Space Nuclear Power System Radiation Shield, Benjamin R. Kowash

Theses and Dissertations

A parameter study was conducted for a space nuclear reactor radiation shield. The focus of this research was to explore alternatives to current radiation shield designs to reduce the mass while maintaining the same shielding performance. MCNP4C was used to determine the parameters necessary to build an optimum shield. A design known as the split scatter shield offered some potential for reductions in shield mass. In theory, less material is required for this type of shield, which uses thin shield sections to scatter radiation away from the dose plane. The parameters for this shield design are the shield geometry, number …

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An Interactive Decision Support System For Scheduling Fighter Pilot Training, Cuong T. Nguyen Mar 2002

An Interactive Decision Support System For Scheduling Fighter Pilot Training, Cuong T. Nguyen

Theses and Dissertations

The U.S. Air Force is developing Modular Aircraft Support System (MASS) program to replace the current Aerospace Ground Equipment (AGE). AGE supplies electricity, nitrogen, hydraulics and other support equipment to maintenance activities at the flight line. Current AGE makes up one-third of the deployment footprint. AGE is also mostly aircraft specific, and has reliability problems. The MASS alternative focuses on modularity based on a plug-and-play approach. The technological improvements and possible reduction in the footprint make MASS a good alternative. The AF has to determine now, whether MASS can supply similar functionality and decrease the deployment footprint to theater, while …

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Modeling And Analysis Of Multicommodity Network Flows Via Goal Programming, Matthew A. Scott Mar 2002

Modeling And Analysis Of Multicommodity Network Flows Via Goal Programming, Matthew A. Scott

Theses and Dissertations

In this research we focused on the mobility system modeled by the AMC mobility planner's calculator (AMPCALC). We developed AMPCALC as a user-friendly tool and allow the user to easily carry out strategic airlift, air refueling and aeromedical evacuation calculations that are covered in Air Force Pamphlet 10-1403. In this study, Excel software and its macro language, Visual Basic for Application, are our two main tools. In the methodology of the thesis we examined fundamental aspects of the mobility system in AMPCALC. We discussed formulation logic of the mobility cycle. We presented ramp use optimization and tanker optimization processes. We …

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