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2001

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Articles 1141 - 1170 of 1795

Full-Text Articles in Engineering

Malicious Hackers: A Framework For Analysis And Case Study, Laura J. Kleen Mar 2001

Malicious Hackers: A Framework For Analysis And Case Study, Laura J. Kleen

Theses and Dissertations

Recent years have seen an increase in the number and severity of Information Operations (IO) attacks upon DoD resources. At a higher level, the US as a whole has come under cyber attack by individuals and groups seeking thrills, monetary gain, publicity for their causes, and myriad other goals. This effort develops a first cut model of individual hacker mentality that can be utilized to improve threat assessment, mitigate Information Assurance (IA) vulnerabilities, and improve risk assessment. Further, it is a first step toward automated characterization of Information Warfare (IW) attacks based upon hacker types. All hackers are not the …

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Using Statistical Process Control Methods To Classify Pilot Mental Workload, Terence Y. Kudo Mar 2001

Using Statistical Process Control Methods To Classify Pilot Mental Workload, Terence Y. Kudo

Theses and Dissertations

The problem of classifying pilot mental workload is important to the United States Air Force. Pilots are more subject to errors and G-induced loss of consciousness during periods of mental overload and task saturation. Often the result is the loss of aircraft, and in extreme cases, the loss of the pilot's life. Current research efforts use different psychophysiological features to classify pilot mental workload. These include cardiac, ocular, respiratory, and brain activity measures. The focus of this effort is to apply statistical process control methodology on different psychophysiological features in an attempt to classify pilot mental workload. The control charts …

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Redundant Wavelet-Based Image Restoration Using A Prior Information, Mary K. Marcum Mar 2001

Redundant Wavelet-Based Image Restoration Using A Prior Information, Mary K. Marcum

Theses and Dissertations

Reconnaissance missions and satellites collect hundreds of images loaded with valuable information to be utilized by the Air Force. Intelligence operations must analyze these images to extract the information needed to help commanders make important decisions. No matter how obtained, images of this type are often degraded by noise due to disruptions such as atmospheric disturbances, optical system variations, motion, and large distance from the sensor to the source. This noise must be removed effectively to improve the quality of these images and ensure that the information contained in them can be correctly extracted. The Air Force relies on the …

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The Effect Of Improving The Logistics Pipeline On Supply Support Of Aerospace Expeditionary Forces, Steven L. Martinez Mar 2001

The Effect Of Improving The Logistics Pipeline On Supply Support Of Aerospace Expeditionary Forces, Steven L. Martinez

Theses and Dissertations

One of the biggest considerations for an Aerospace Expeditionary Force (AEF), in terms of cost and airlift requirement, is the use of aircraft spares kits to support combat operations. To date, these kits are built on the assumption that there would be no resupply for the first 30 days of a contingency. However, with more efficient transportation and information resources available today, it seems logical that resupply would occur much more quickly. If so, the Air Force should be able to trim its wartime stocks of aircraft spares. This thesis investigated the effect of improving the logistics pipeline on the …

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The Development Of A Finite Element Program To Model High Cycle Fatigue In Isotropic Plates, William C. Shipman Mar 2001

The Development Of A Finite Element Program To Model High Cycle Fatigue In Isotropic Plates, William C. Shipman

Theses and Dissertations

As part of a joint AFRL/DAGSI turbine blade research effort, a computer program has been developed that uses a von Karman large-deflection two-dimensional finite element approximation to determine stress levels and patterns in isotropic thin plates. The dynamic loading of various plates has been carried out in order to model a high cycle fatigue situation. The research considered the various effects of mode shapes, resident frequency, non-linear cyclic effect, endurance limits, and stress variations within a high cycle fatigue environment. Two main initiatives were taken. First, a transient analysis tool was developed that calculates stress and displacement patterns over a …

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Using Direct-Sequenced Spread Spectrum In A Wired Local Area Network, Robert J. Bonner Mar 2001

Using Direct-Sequenced Spread Spectrum In A Wired Local Area Network, Robert J. Bonner

Theses and Dissertations

Code division multiple access provides an ability to share channel bandwidth amongst users at the same time. Individual user performance is not degraded with the addition of more users, unlike traditional Ethernet. Using direct sequenced spread spectrum in a wired local area network, network performance is improved. For a network in overload conditions, individual station throughput is increased by nearly 212% while mean end-to-end delay was reduced by 800%. The vast improvement demonstrated by this research has the capability to extend legacy-cabling infrastructures for many years to come while easily accommodating new bandwidth intensive multimedia applications.

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Modeling Information Assurance, Joseph E. Beauregard Mar 2001

Modeling Information Assurance, Joseph E. Beauregard

Theses and Dissertations

The ever-increasing speed of information systems allows decision-makers around the world to gather, process, and disseminate information almost instantaneously. However, with this benefit there comes a price. Information is valuable and therefore a target to those who do not have it or wish to destroy it. The Internet has allowed information to flow freely, but it has also made information vulnerable to many forms of corruption. The U. S. military controls much of the world's most sensitive information, and since it cannot sacrifice losing the speed at which this information is currently processed and disseminated, it must find a way …

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Using Gps As A Reference System To Hit A Moving Target, Daryl J. Burnette Mar 2001

Using Gps As A Reference System To Hit A Moving Target, Daryl J. Burnette

Theses and Dissertations

The Affordable Moving Surface Target Engagement (AMSTE) project attempts to develop affordable solutions to the precise moving target surface target engagement problem. Up to this point, most of the error analysis performed for the AMSTE project has been at the error variance level, generating root-sum-square (RSS) total errors from error budgets consisting of constant error variances. In reality, the level of error for both Global Positioning System (GPS) positioning and radar targeting systems is highly dependent upon the given situation (such as the distance between sensor and target, the altitude differences, etc.) This research generates a more comprehensive model of …

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The Effects Of Budgetary Constraints, Multiple Strategy Selection, And Rationality On Equilibrium Attainment In An Information Warfare Simulation, Steven W. Tait Mar 2001

The Effects Of Budgetary Constraints, Multiple Strategy Selection, And Rationality On Equilibrium Attainment In An Information Warfare Simulation, Steven W. Tait

Theses and Dissertations

Information warfare (IW) has developed into a significant threat to the national security of the United States. Our critical infrastructures, linked together by information systems, are increasingly vulnerable to information attack. This study seeks to understand some of those factors which affect the ability of an individual to make accurate decisions in an IW environment. The study used game theory to analyze the behavior of decision-makers within an IW simulation. The IW game model is based on a set of games known as infinitely repeated games of incomplete information. It uses the Bayesian Nash equilibrium concept to determine the strategy …

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Minimum Distance Estimation For Time Series Analysis With Little Data, Hakan Tekin Mar 2001

Minimum Distance Estimation For Time Series Analysis With Little Data, Hakan Tekin

Theses and Dissertations

Minimum distance estimate is a statistical parameter estimate technique that selects model parameters that minimize a good-of-fit statistic. Minimum distance estimation has been demonstrated better standard approaches, including maximum likelihood estimators and least squares, in estimating statistical distribution parameters with very small data sets. This research applies minimum distance estimation to the task of making time series predictions with very few historical observations. In a Monte Carlo analysis, we test a variety of distance measures and report the results based on many different criteria. Our analysis tests the robustness of the approach by testing its ability to make predictions when …

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A Verification And Validation Assessment Of Rapid Availability Prototyping For Testing Operational Readiness, Gurhan Tarman Mar 2001

A Verification And Validation Assessment Of Rapid Availability Prototyping For Testing Operational Readiness, Gurhan Tarman

Theses and Dissertations

Throughout the world, new techniques are developed to test and evaluate systems. The Department of Defense and the US Air Force conduct numerous studies into the reliability and maintainability of current and future weapons systems in an effort to understand the reliability, maintainability, and availability (RM&A) costs of these systems. Furthermore, they must verify RM&A characteristics of systems, which are still in the development phase. The Air Force Operational Test and Evaluation Center (AFOTEC) is responsible for testing new equipment to ensure their RM&A characteristics meet specifications. Rapid Availability Prototyping for Testing Operational Readiness (RAPTOR) is the software tool developed …

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A Reactive Tabu Search Metaheuristic Extension Of The Air Refueling Tanker Assignment Problem, Umit Hilmi Tekelioglu Mar 2001

A Reactive Tabu Search Metaheuristic Extension Of The Air Refueling Tanker Assignment Problem, Umit Hilmi Tekelioglu

Theses and Dissertations

The Combined Mating and Ranging Planning System (CMARPS) is the system used by AMC to schedule air refueling for deployments from the continental U.S. to other parts of the world. The tool developed by Capehart (2000) got results similar to CMARPS in less time. Capehart's tool allows AMC to input several receiver groups consisting of various aircraft types and numbers. Each receiver group contains a point of origin and destination, with the option of providing one waypoint along the path, a ready to load date (RLD) and required delivery date (RDD). The user is also able to specify the locations …

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A Case Study Analysis Of The Overhead Rate Impact Model Used During The C-5 Maintenance Source Selection, William N. Ward Mar 2001

A Case Study Analysis Of The Overhead Rate Impact Model Used During The C-5 Maintenance Source Selection, William N. Ward

Theses and Dissertations

The Overhead Rate Impact (ORI) model was used during the C-5 Maintenance source selection to evaluate the impact the new workload would have on the existing overhead rates. The objectives of this research study were to evaluate the ORI model and to identify the lessons learned from this source selection. To accomplish these objectives, interviews were conducted with members of the source selection team who were on the Cost Integrated Product Team (IPT). The experts were asked to identify the strengths and weaknesses of the ORI model and to make recommendation on how to improve the model. This study identified …

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An Analysis Of Total System Performance Responsibility In Air Force Acquisitions, Christopher P. White Mar 2001

An Analysis Of Total System Performance Responsibility In Air Force Acquisitions, Christopher P. White

Theses and Dissertations

This research examined how well the goals and objectives of total system performance responsibility (TSPR) are being met. The research was sparked by the rise of implementing TSPR as an element of an acquisition strategy in many weapon and information systems. Acquisition professionals use TSPR to decrease total ownership cost, improve system performance, and optimize public-private support capabilities while maintaining operational flexibility. However, while the number of programs that use or plan to implement TSPR or some form of contractor support and sustainment continues to increase, little research has been conducted concerning the effectiveness of TSPR as an element of …

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Technology Selection For Enhancing F-16 Capability: An Analysis Using Value Focused Thinking, Cihangir Yay Mar 2001

Technology Selection For Enhancing F-16 Capability: An Analysis Using Value Focused Thinking, Cihangir Yay

Theses and Dissertations

This study, with support of the Aeronautical Systems center, builds a scientific decision support system intended for Air Combat Command. Past decision-making techniques are discussed and their limitations are explained. Two multiattribute decision-making techniques, analytical hierarch process and value focused thinking, are studied. Due to limitations of analytical hierarchy process, value focused thinking is accepted as the best fit for our problem. A value hierarchy model is developed using value focused thinking for selecting the most beneficiary F-16 engine modifications depending on Air Combat Command values. Ten modifications are ranked using value model to validate the process. Cost is involved …

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Quantitative Validation Of A Model Of Chlorinated Ethene Natural Attenuation, Harold C. Young Mar 2001

Quantitative Validation Of A Model Of Chlorinated Ethene Natural Attenuation, Harold C. Young

Theses and Dissertations

Chlorinated ethenes are among the most prevalent groundwater contaminants at hazardous waste sites nationwide. In an attempt to manage the risks posed by these contaminants, while controlling costs, monitored natural attenuation (MNA) is being considered as a remediation strategy at many sites. MNA relies on naturally occurring physical, chemical, and biological processes in the subsurface to reduce the risk posed by the contamination. The implementation of MNA, however, requires a detailed understanding of these processes, and how they impact contamination at a particular site. One way to gain this understanding is through contaminant fate and transport modeling. In this study, …

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The Distributer's Three-Dimensional Pallet-Packing Problem: A Human Intelligence-Based Heuristic Approach, Erhan Baltacioglu Mar 2001

The Distributer's Three-Dimensional Pallet-Packing Problem: A Human Intelligence-Based Heuristic Approach, Erhan Baltacioglu

Theses and Dissertations

The Distributor's Pallet Packing Problem is to load a set of distinct boxes with given dimensions on pallets or in containers to maximize volume utilization. This problem is still in its early stages of research, but there is a high level of interest in developing effective models to solve this NP-hard problem to reduce the time, energy and other resources spent in packing pallets. In its search to improve operations, the Air Force is also making an effort to solve this problem. Building an analytical model and developing a genetic algorithm approach have been tried, but the problem needs more …

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Photoluminescence Of Single Quantum Well Structures In Gallium Arsenide, Christian A. Bartholomew Mar 2001

Photoluminescence Of Single Quantum Well Structures In Gallium Arsenide, Christian A. Bartholomew

Theses and Dissertations

The continued development of state-of the-art semiconductor technologies and devices by the United States Air Force and the Department of Defense requires accurate and efficient techniques to evaluate and model these new materials. Of particular interest to the Air Force are quantum well structures which can be used for small-scale laser sources in fly-by-light applications, as efficient infrared countermeasures to heat-seeking missiles, or as advanced seekers in optically guided missiles. This thesis provides the initial experimental procedures and data necessary to begin producing accurate yet robust models. Although carrier effective masses could not be evaluated using hot-electron photoluminescence, photoluminescence excitation …

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Optical And Etching Studies Of Native Aluminum Oxide Layers For Use In Microcavity Photonic Devices, William L. Bernhard Mar 2001

Optical And Etching Studies Of Native Aluminum Oxide Layers For Use In Microcavity Photonic Devices, William L. Bernhard

Theses and Dissertations

Optical communication and computing systems are required to meet future information transfer and processing needs. Microcavity devices serve as an enabling technology to implement and integrate optoelectronic systems. It is important to understand the optical and mechanical properties of materials utilize within microcavity devices. Only then is it possible to accurately model and analyze structures. Microcavity structures incorporating a high aluminum content AlGaAs layers are designed, grown, processed, and measured. The processing of these devices includes the conversion of high aluminum-content AlGaAs layers to native aluminum oxide (AlO) layers through the process of thermal oxidation. This selective conversion of microcavity …

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The Use Of Systems Engineering Processes And Tools To Develop A System Dynamic Simulation Model Of Engineering Support During The Development Phase Of An Acquisition Program, Jason E. Bartolomei Mar 2001

The Use Of Systems Engineering Processes And Tools To Develop A System Dynamic Simulation Model Of Engineering Support During The Development Phase Of An Acquisition Program, Jason E. Bartolomei

Theses and Dissertations

Due to the increase of system complexity and the existing draw down of manpower allocations, today's acquisitions environment desperately needs a systems approach to decision making. Many studies have been performed to model the entire government acquisition environment. Due to the high degree of aggregation, front line decision-makers have had no use for the information these models provide. This research focuses on the Air Force's largest functional support element in aircraft systems development, engineering. I will only consider one phase of the government acquisition cycle the Engineering, Manufacturing, and Development (EMD). This is the development cycle, which begins with initial …

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Robust Multi-Scenario Optimization Of An Air Expeditionary Force Structure Applying Scatter Search To The Combat Forces Assessment Model, Gokay Bulut Mar 2001

Robust Multi-Scenario Optimization Of An Air Expeditionary Force Structure Applying Scatter Search To The Combat Forces Assessment Model, Gokay Bulut

Theses and Dissertations

Modern Times' bring change in all areas of life. Even the rate of change has changed, and is still changing to increase it's enormous speed even more. Newer and more challenging questions face the military analysts everyday putting a question mark at the end of their last answer. Recently, the question of how to structure a robust air force to meet the requirements of competing, uncertain future scenarios has been keeping them busy. The new world order does not tolerate only being able to respond to a single scenario anymore, which once was considered a hard problem. Who knows what …

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Electronic Quenching Of The A(0+U) State Of Bi2, Joseph L. Cox Mar 2001

Electronic Quenching Of The A(0+U) State Of Bi2, Joseph L. Cox

Theses and Dissertations

Temporally-resolved laser induced fluorescence ofhigh vibrational levels in Bi2 A(0+u) above and below the predissociation limit of v'=22 were investigated by observing total fluorescence from a wavelength tunable, pulsed dye laser. Electronic quenching ofBi2 A(0+u) by five collision partners (Ne, Ar, Kr, Xe, N2) was examined for four vibrational levels (v'=22,23,24,25). Electronic quenching by a sixth collision partner (He) was examined for eight vibrational levels (v'=18 through 25). The quenching from stable vibrational levels (v'≤22) was independent ofvibrational quantum number. A significant increase in quenching occurs for the predissociated level …

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Aircraft Maintenance Performance: The Effects Of The Functional Decentralization Of On-Equipment Maintenance, Mark A. Commenator Mar 2001

Aircraft Maintenance Performance: The Effects Of The Functional Decentralization Of On-Equipment Maintenance, Mark A. Commenator

Theses and Dissertations

The Air Force has implemented various aircraft maintenance organizational structures. The implementation of the Objective Wing in the early 1990s was the latest occurrence of reorganization. This research looks at the effect of the type of aircraft maintenance organizational structure on aircraft maintenance performance. The type of organizational structure was defined by the functional centralization of the on-equipment maintenance. Aircraft maintenance performance was measured using TNMCM rates, fix rates, repeat/recur rates, man-hours per flying hour, and scheduling effectiveness rates. Three F-15 wings and three F-16 wings were selected to compare the changes in aircraft maintenance performance and to determine if …

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Environmental Disturbance Modeling For Large Inflatable Space Structures, Donald J. Davis Mar 2001

Environmental Disturbance Modeling For Large Inflatable Space Structures, Donald J. Davis

Theses and Dissertations

Tightening space budgets and stagnating spacelift capabilities are driving the Air Force and other space agencies to focus on inflatable technology as a reliable, inexpensive means of deploying large structures in orbit. Recent improvements in rigidization techniques make the use these inflatable structures feasible for a growing number of missions. For many of these missions, the primary design requirement is dimensional accuracy of the structure. Finite element analysis offers a means of predicting structural behavior in orbit. The analysis requires knowledge of external loads. This thesis examines the environmental disturbances which act upon large, orbiting structures. Calculations are made on …

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Numerical Study Of Optical Delay In Semiconductor Multilayer Distributed Bragg Reflector And Tunable Microcavity Structures, Michael I. K. Etan Mar 2001

Numerical Study Of Optical Delay In Semiconductor Multilayer Distributed Bragg Reflector And Tunable Microcavity Structures, Michael I. K. Etan

Theses and Dissertations

The Air Force has a growing need for the greater bandwidth, speed, and flexibility offered by optical communication links. Future space systems and airborne platforms will most likely use optical signals for efficient power transmission and to minimize the possibility of spoofing and eavesdropping. Tunable optical delays play an important role in the implementation of free space optical communication links. The primary challenge in implementing these systems is the active maintenance of coherent wave fronts across the system's optical aperture. For space applications, this aperture may he hundreds of meters in diameter. Spatial segmentation of a large aperture into smaller …

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Characterization And Validation Of The Gp-3 Experimental Radar System, Benjamin L. Crossley Mar 2001

Characterization And Validation Of The Gp-3 Experimental Radar System, Benjamin L. Crossley

Theses and Dissertations

The experimental GP-3 radar system was originally designed and built under contract for the Air Force Research Laboratory (AFRL). AFRL sought AFIT's support in characterizing the as delivered' performance of the GP-3. This research effort focused exclusively on software modifications and hardware validations related to the GP-3 post-processing mode. As modified, tested, and validated, the GP-3's post-processing mode is now fully operational. The GP-3 is capable of transmitting and receiving bandlimited (3.5 MHz) waveforms at X-Band frequencies. System characterization tests included, noise performance and frequency response. System noise performance characterization permitted establishment of the receiver 'noise floor' and enabled determination …

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Aircrew Ionizing Doses From Nuclear Weapon Bursts, Fred E. Garcia Ii Mar 2001

Aircrew Ionizing Doses From Nuclear Weapon Bursts, Fred E. Garcia Ii

Theses and Dissertations

Total radioactive doses to aircrew members have been calculated in the past using different methods. The methodologies include smearing models, disk-tosser codes, and puff models. This study uses output data from the Hazard Prediction and Assessment Capability (HPAC) code as input into a FORTRAN program written by the author to calculate total dose to aircrew members through sky-shine and cabin ingestion. A description of the input parameters and new project setup in the Nuclear Weapon (NWPN) module within HPAC is given. The various aspects of controlling the project and plotting the data are also described. This information is presented essentially …

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Broadband Application Of High Impedance Ground Planes, Keven J. Golla Mar 2001

Broadband Application Of High Impedance Ground Planes, Keven J. Golla

Theses and Dissertations

Electrical conductors have long been the only materials available to antenna designers for reflecting structures. However, recently reported high impedance ground plane (HIGP) structures offer an alternative by creating image currents and reflections, within a limited frequency stop-band, that are in-phase with a source rather than out-of-phase as for a perfect electric conducting (PEC) surface. Also, the high impedance structures suppress surface waves while surface waves propagate on PEC surfaces. This research explores broadband antenna applications for HIGP structures. A broadband surface mount antenna is applied to both a homogeneous narrowband HIGP and a spatially varying broadband HIGP design. Measurements …

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Vibration Suppression Of A Rotationally Periodic Structure Using An Adaptive/Ppf Control Law, Mark J. Keller Mar 2001

Vibration Suppression Of A Rotationally Periodic Structure Using An Adaptive/Ppf Control Law, Mark J. Keller

Theses and Dissertations

For a compressor disk, effective vibration suppression requires broadband control, and the elimination of inter-blade coupling forces. Previous researchers achieved this using an active/passive piezoelectric shunt network. Unfortunately, optimal tuning of the shunt requires prior knowledge of the coupling strength, which is not well defined. This thesis uses an adaptive parameter estimator to eliminate the inter-blade coupling forces. In addition, the passive shunt is replaced with an analogous positive position feedback method. The resulting control law was used on a simulated four and eight bladed system. While substantial reductions in system response were achieved for the Adaptive/PPF control technique, the …

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Weapon System Environmental Life Cycle Cost Methodologies And Models, William H. Kale Iii Mar 2001

Weapon System Environmental Life Cycle Cost Methodologies And Models, William H. Kale Iii

Theses and Dissertations

Major Defense Acquisition Programs (MDAP) cost billions of dollars and have 30 to 50 year life spans. Numerous (federal, state, etc.) laws, Environmental Protection Agency regulations, and Executive Orders have driven DoD to develop and implement significant environmental policies within the past ten to fifteen years. Congressional mandate now requires each MDAP to evaluate its environmental life cycle cost (ELCC) to minimize these costs. This research focuses on the current methodologies and models used to predict and calculate the ELCC of a MDAP. This thesis analyzed the difficulties associated with using ELCC methodologies and models and examined several case studies …

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