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Articles 1171 - 1200 of 1334

Full-Text Articles in Civil and Environmental Engineering

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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Modeling Biodegradation Of Chlorinated Groundwater Contaminants Under Iron-Reducing Conditions Of A Constructed Wetland: A System Dynamics Approach, Max E. Johnson Mar 2001

Modeling Biodegradation Of Chlorinated Groundwater Contaminants Under Iron-Reducing Conditions Of A Constructed Wetland: A System Dynamics Approach, Max E. Johnson

Theses and Dissertations

The purpose of this study is to determine and explore the fundamental processes associated with biodegradation of chlorinated ethenes in iron-reducing conditions of a constructed wetland and to evaluate the impacts of changing conditions (both natural and engineer-controlled) on the system. The modeler uses a system dynamics approach to construct a model that represents behavior in the iron-reducing environment. The model incorporates hematite, a form of oxidized iron (Fe3+), as the electron acceptor in microbial biodegradation in the system. Vinyl chloride, cis-dichloroethene, and trans-dichloroethene are known to anaerobically degrade to carbon dioxide in the presence of oxidized iron. …

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A System Dynamics Approach To Modeling Temperature Effects In Solid Waste, David A. Jokinen Mar 2001

A System Dynamics Approach To Modeling Temperature Effects In Solid Waste, David A. Jokinen

Theses and Dissertations

The amount of municipal solid waste discarded to landfills is continually increasing even with extensive recycling efforts. The need to understand the behavior of waste in landfills is increased due to the decreasing number of active landfills, communities' concern to the potential hazards associated with landfills, and companies or installations with landfills on-site need to understand landfill behavior comply with new legislation concerning design and detecting hazardous material movement of-site. This research is focused on increasing the understanding of landfill behavior by examining the effects of temperature in a landfill system. A system dynamics approach was used in this research …

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Chromate Content Bias As A Function Of Particle Size In Aircraft Primer Paint Overspray, David B. Novy Mar 2001

Chromate Content Bias As A Function Of Particle Size In Aircraft Primer Paint Overspray, David B. Novy

Theses and Dissertations

Spray painting operations using chromate-containing primer paints produce particles which may expose workers to strontium chromate. Chromate contains hexavalent chromium (Cr(VI)) which is a confirmed human carcinogen. It is suspected that the smaller particles contain disproportionately less Cr(VI) than larger particles. In order to determine if a bias in chromate content exists, paint particles were collected and separated based on particle size and the Cr(VI) concentration was determined. Aviation primer paint from the DeSoto and Deft companies was sprayed in a booth and seven-stage cascade impactors were used to separate particles.

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A Model For Palladium Catalyzed Destruction Of Chlorinated Ethenes In Contaminated Groundwater, Christopher M. Stoppel Mar 2001

A Model For Palladium Catalyzed Destruction Of Chlorinated Ethenes In Contaminated Groundwater, Christopher M. Stoppel

Theses and Dissertations

Groundwater contamination by chlorinated ethenes is a widespread environmental problem. Conventional remediation technologies have shortcomings that have prompted further research into the development of novel treatment technologies. A palladium/ alumina catalyst in the presence of dissolved molecular hydrogen (referred to hereafter as a PD/H2 system) has been demonstrated to rapidly destroy chlorinated ethene contaminated groundwater. First-order kinetics have been used to model chlorinated ethene destruction in a PD/H2 reactor. However, catalyst deactivation and regeneration are important processes that also need to be modeled in order to better understand their effect on treatment efficiency. This study presents a model …

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Decision Analysis Methodology To Evaluate Integrated Solid Waste Management Alternatives For A Remote Alaskan Air Station, Mark J. Shoviak Mar 2001

Decision Analysis Methodology To Evaluate Integrated Solid Waste Management Alternatives For A Remote Alaskan Air Station, Mark J. Shoviak

Theses and Dissertations

Eareckson Air Station (AS), a remote U.S. Air Force installation, faces the complex decision of selecting a new municipal solid waste (MSW) management strategy to replace its current non-compliant system. This research effort applies value-focused thinking and multiattribute preference theory to decision analysis techniques to produce a multiple-objective decision analysis model that captures all of the site's MSW goals, objectives, and concerns in order to facilitate the evaluation of MSW management strategies available. The model ranks 40 specific MSW management alternatives, which were developed in accordance with the decision-maker's assumptions and constraints, based on how well they meet Eareckson's overall …

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An Analysis Of Civil Engineer Officer Contingency Training, Rusty J. Vaira Mar 2001

An Analysis Of Civil Engineer Officer Contingency Training, Rusty J. Vaira

Theses and Dissertations

The primary objective of this research was to investigate the current overall civil engineer officer contingency training program and determine if civil engineer officers think it is adequately preparing them to perform in a contingency environment. In accomplishing this objective, this research explored the perceptions that officers have about the contingency training that is available through three primary training programs (Home Station Training, Silver Flag training, and Civil Engineer and Services School training). The overall intent of the author was to gauge how the officers feel about their contingency training and offer some suggestions on how to improve the training. …

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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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Differences In Civil Engineer Perceptions Of Change Based On Prior Training And Experience, Steven W. Lo Mar 2001

Differences In Civil Engineer Perceptions Of Change Based On Prior Training And Experience, Steven W. Lo

Theses and Dissertations

The Department of Defense (DoD) and the United States Air Force (USAF) have moved toward an aggressive stance to competitively source and privatize (CS&P) support functions as much as possible. This move is intended to shrink support costs and redirect the savings to force and equipment modernization. In addition, the USAF hopes to realize improved services, gain access to technology, share risks with contractors, and allow its forces to focus on the core competencies. In order to implement OS&P, the USAF communicates information through two major pathways, passive and active. Passive communication is similar to traditional classroom learning where information …

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Determining The Value Of Groundwater Contamination Source Removal: A Methodology, Benjamin C. Recker Mar 2001

Determining The Value Of Groundwater Contamination Source Removal: A Methodology, Benjamin C. Recker

Theses and Dissertations

Subsurface contamination by industrial chemicals is one of the most prevalent and costly environmental problems facing the United States government. This contamination problem must be managed to protect human health and the environment. Two basic strategies are used to deal with subsurface contamination: source removal and contaminant containment. While much cost and performance data are available for individual technologies associated with each of these strategies, there have been very few studies that have examined the benefits of implementing source removal technologies in order to reduce contaminant containment (and hopefully total) costs. This study examines the tradeoff between extent of source …

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Modeling Chlorinated Ethene Removal In The Methanogenic Zone Of Constructed Wetlands: A System Dynamics Approach, Randall L. Roberts Mar 2001

Modeling Chlorinated Ethene Removal In The Methanogenic Zone Of Constructed Wetlands: A System Dynamics Approach, Randall L. Roberts

Theses and Dissertations

The purpose of this study is to gain understanding of the dynamics of the processes that degrade Perchloroethene (PCE) to ethene, within the confines of the methanogenic zone of a constructed wetland. A system dynamics modeling approach is used. This model is focused on determining conditions that will enhance contaminant degradation. The chemical and biological processes within the methanogenic zone of a wetland system are extremely complex and dynamic processes. The model is broken up into three simultaneous processes: dechlorination, methanogenesis, and fermentation. The system behavior of the methanogenic zone can be adequately described by the classical formulations of representative …

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Life-Cycle Cost Analysis: A Computer Aided Tool For The Egyptian Construction Industry, Ahmed Mohamed Ahmed Ibrahim Jan 2001

Life-Cycle Cost Analysis: A Computer Aided Tool For The Egyptian Construction Industry, Ahmed Mohamed Ahmed Ibrahim

Theses and Dissertations

The construction industry can be considered as an indication of economical status of any country.

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In Situ Treatment Of Chlorinated Ethene-Contaminated Groundwater Using Horizontal Flow Treatment Wells, Derek R. Ferland Mar 2000

In Situ Treatment Of Chlorinated Ethene-Contaminated Groundwater Using Horizontal Flow Treatment Wells, Derek R. Ferland

Theses and Dissertations

The limitations of conventional containment technologies for groundwater contaminated with chlorinated solvents have motivated development of innovative technologies to achieve national groundwater remediation objectives. One inn9vative technology that is currently under development involves metal reductants or catalysts to chemically destroy the dissolved chlorinated solvent. Models are important tools that can be used to help transition this technology to the field. Model studies can be used to gain understanding about the technology, help determine when the prospective technology might work for a given site, and design full-scale field applications.

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Cost Analysis Between Saber And Design Bid Build Construction, Elwood Henry Mar 2000

Cost Analysis Between Saber And Design Bid Build Construction, Elwood Henry

Theses and Dissertations

The purpose of this research was to perform a cost analysis between DBB and SABER construction. The research involved traveling to Wright-Patterson and Holloman Air Force Bases to gather project information on comparable projects completed by both methods. There were a total of 46 projects collected from both bases. A methodology was developed to compare the projects completed. Projects were divided into categories containing similar types of construction. Data from the project was then used to calculate a unit cost for the project. Project comparability was demonstrated by showing the projects constructed by each method completed a similar type and …

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Modeling The Effect Of Nonlinear And Rate-Limited Sorption On The Natural Attenuation Of Chlorinated Ethenes, Peter P. Feng Mar 2000

Modeling The Effect Of Nonlinear And Rate-Limited Sorption On The Natural Attenuation Of Chlorinated Ethenes, Peter P. Feng

Theses and Dissertations

Chlorinated solvents like tetrachloroethene (PCE) and trichloroethene (TCE) are the most common detected groundwater contaminants at Department of Defense installations in the United States. Unfortunately, technologies conventionally used to remediate chlorinated solvent-contaminated groundwater often fall short of achieving regulatory goals. Natural attenuation of chlorinated solvents offers an alternative remediation strategy that may achieve goals. However, the processes involved with natural attenuation are not fully understood, and this lack of understanding has hindered acceptance of natural attenuation by regulatory agencies. This study involved use of a numerical model that incorporated the physical, chemical, and biological processes thought to be relevant to …

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Use Of Genetic Algorithms To Characterize Groundwater Contamination Source Areas, Chaz M. Williamson Mar 2000

Use Of Genetic Algorithms To Characterize Groundwater Contamination Source Areas, Chaz M. Williamson

Theses and Dissertations

In this work, genetic algorithms (GAs) were used to help interpret tracer breakthrough curves from partitioning interwell tracer tests (PITTs) conducted at Hill AFB, Utah by researchers from the University of Florida. Two transport models were developed to simulate tracer transport in the test cells. One model assumed the cell consisted of multiple layers, and that transport in each layer could he described by the one-dimensional advective/dispersive equation. The second model also assumed multiple layers, and modeled transport in the individual layers as advective transport through 100 tubes. Transport times were represented by a stochastic (lognormal) distribution. The model solutions …

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Effects Of Moisture Content In Solid Waste Landfills, Craig P. Eck Mar 2000

Effects Of Moisture Content In Solid Waste Landfills, Craig P. Eck

Theses and Dissertations

Solid waste landfills are an extremely complex and heterogeneous environment. Modeling the biodegradation processes within a landfill must involve an understanding of how environmental factors affect these processes. Arguably, the most important environmental factor influencing biodegradation processes is solid waste moisture content. This research effort, which is an extension of a system dynamics model previously presented by Colborn (1997) and amended by Benter (1999), attempts to understand and model the effects of moisture content on waste degradation and landfill gas generation. The new moisture structure that was added to the previous models provides a better representation of the impact of …

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Analysis Of The Air Force Iso 14001 Pilot Study Conducted By Dod, Rodney C. Harris Mar 2000

Analysis Of The Air Force Iso 14001 Pilot Study Conducted By Dod, Rodney C. Harris

Theses and Dissertations

The Department of Defense (DoD) conducted an ISO 14001 pilot study with the primary goal of determining how ISO 14001 could help DoD organizations reduce risks, improve compliance with environmental regulations, enhance stewardship, contain costs, and meet emerging regulatory requirements. This thesis analyzed the pilot study, specifically looking at the ISO 14001 implementation at three Air Force installations participating in the study. The research objectives were to identify factors that affect implementation of ISO 14001, compare the implementation strategies used by the bases, and develop propositions for Air Force managers to consider when implementing ISO 14001. Interviews of key personnel, …

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The Influence Of Outsourcing On Job Satisfaction And Turnover Intentions Of Air Force Civil Engineer Company Grade Officers, James F. Kennedy Mar 2000

The Influence Of Outsourcing On Job Satisfaction And Turnover Intentions Of Air Force Civil Engineer Company Grade Officers, James F. Kennedy

Theses and Dissertations

A survey was distributed to 865 active duty Air Force Civil Engineer company grade officers (CGOs) assigned to locations throughout the world. The survey was designed to assess the CGOs' current job satisfaction and their intentions towards making a career out of the Air Force. Additionally, the survey measured the CGOs' perceptions of outsourcing, and how they feel that it will influence the Civil Engineer career field. Relationships were evaluated between the perceptions of outsourcing and job satisfaction, and between job satisfaction and turnover intentions. Overall, Civil Engineer CGOs reported a slightly positive level of satisfaction and a negative perception …

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Empirical Evaluation Of The Civil Engineer Career Pyramid And Career Guidance, Travis K. Leighton Mar 2000

Empirical Evaluation Of The Civil Engineer Career Pyramid And Career Guidance, Travis K. Leighton

Theses and Dissertations

Air Force civil engineer officers rely on published guidance to assist in establishing their career objectives. This thesis uses empirical data to evaluate the published Air Force career guidance. The data set is comprised of complete duty histories from all active duty lieutenant colonels in the civil engineer career field. The guidance implies a career path to become a civil engineer squadron commander but provides no empirical validation. This thesis follows a rigorous procedure to objectively evaluate the Air Force guidance. The guidance is translated into 24 research questions based on its main tenets. Each duty occurrence is categorized by …

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Boundary Control For Automated Sweeping Of Finite Element Meshes, Robert A. Kerr Dec 1999

Boundary Control For Automated Sweeping Of Finite Element Meshes, Robert A. Kerr

Theses and Dissertations

Finite element analysis depends greatly upon a high-quality mesh to be able to provide reasonably accurate answers to engineering problems. Models that need to be analyzed using finite element analysis are becoming increasingly more complex, and correspondingly harder to mesh with good quality. Skew is one quality metric which can cause problems with finite element analyses. This thesis explains how skew is calculated, discusses two common sources of skew: multiply-linked surfaces with interval constraints, and biased edge meshes. Two methods of lessening skew in surface meshes are then presented: the skew control algorithm, and the curve morphing algorithm. These algorithms …

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Interval Matching And Control For Hexahedral Mesh Generation Of Swept Volumes, Jason F. Shepherd Apr 1999

Interval Matching And Control For Hexahedral Mesh Generation Of Swept Volumes, Jason F. Shepherd

Theses and Dissertations

Surface meshing algorithms require certain relationships among the number of intervals on the curves that bound the surface. Assigning the number of intervals to all of the curves in the model such that all relationships are satisfied is called interval assignment. Volume meshing algorithms also require certain relationships among the numbers of intervals on each of the curves on the volume. These relationships are not always captured by surface meshing requirements. This thesis presents a news technique for automatically identifying volume constraints. In this technique, volume constraints are grouped with surface constraints and are solved simultaneously. A sweepable volume has …

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Concept Design And Optimization Of Msw Management System, James R. Palmer Mar 1999

Concept Design And Optimization Of Msw Management System, James R. Palmer

Theses and Dissertations

The maximum recovery of recyclables from municipal solid waste (MSW) using material recovery facility (MRF) technologies is determined. Two waste streams at Spangdahlem AB, Germany are analyzed; stationary container wastes and commingled recyclables. Three schemes are considered, one for each waste stream, and one for both. Multi-criteria decision making is the methodology. The criteria are recovery and annual benefit minus cost (B-C). Recovery is determined using the recovery factor transfer function of Diaz et al. (1982). Each technology, or unit operation, in a sequence is independent because particle size distribution of each waste component is considered. B-C is based on …

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Analysis Of Cost Growth In Us Air Force Base Support Function Contracts, James S. Romasz Mar 1999

Analysis Of Cost Growth In Us Air Force Base Support Function Contracts, James S. Romasz

Theses and Dissertations

The United States Air Force (USAF) has outsourced a significant portion of their activities defined as commercial activities and plans to aggressively outsource more in the future. The USAF outsources its commercial activities in the form of multi-year contracts to the private sector. Cost growth (either negative or positive) has been experienced by most of these contracts. This research effort performed a review of current literature and used statistical analysis to clarify the issue: what are the causes, and extent of cost growth in USAF base-support-function contracts?. From the literature, it can be concluded that changes to the statement of …

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Expeditious Methods For Site Characterization And Risk Assessment At Department Of Defense Hazardous Waste Sites In The Republic Of Korea, Dean H. Hartman Mar 1999

Expeditious Methods For Site Characterization And Risk Assessment At Department Of Defense Hazardous Waste Sites In The Republic Of Korea, Dean H. Hartman

Theses and Dissertations

The overall goal of this research was to provide Department of Defense (DoD) decision-makers in the Republic of Korea (ROK) with preferred innovative site characterization technologies and risk assessment methods to meet their needs in obtaining hazardous waste site data and then prioritizing those sites for remediation based upon risk. The study examined the following: primary sources and types of existing contamination at DoD installations in the ROK; available site characterization data; criteria to be used in selecting innovative site characterization technologies; costs and capabilities of the innovative site characterization technologies; risk assessment or risk-based corrective action (RBCA) methods available …

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Exploring The Management Of Outsourcing And The Determination Of Civil Engineering Minimum Manning Numbers In Order To Optimize Air Force Benefits, David J. Anason Mar 1999

Exploring The Management Of Outsourcing And The Determination Of Civil Engineering Minimum Manning Numbers In Order To Optimize Air Force Benefits, David J. Anason

Theses and Dissertations

This thesis investigates the relationship between peacetime and wartime tasks for Air Force Civil Engineering career fields in regard to outsourcing. Relevant literature in civilian sector outsourcing techniques is then studied to determine how they decide on what to outsource and what to keep insourced. Peacetime tasks performed by individual career fields are correlated with the wartime tasks to determine if there is any valuable wartime training gained from the completion of peacetime work orders. Several interviews completed with Air Force Civil Engineer readiness experts to evaluate an importance factor for each career field wartime mission. This importance factor and …

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Substrate Availability In Solid Waste Landfills, Brian D. Benter Mar 1999

Substrate Availability In Solid Waste Landfills, Brian D. Benter

Theses and Dissertations

Numerous models exist to both predict and represent the many biological activities that occur in the modern landfill. These different models use varying methods of characterizing what is happening, what is thought to happen, or what should be happening based on both empirical data and theoretical reasoning. The model presented here is an extension of the system dynamics model originally presented by Colborn in 1997. The revamped model presents a different perspective on what happens as solid organic waste is transformed to simpler substances. This new view involves a bacterial population performing hydrolysis whose growth is limited by the amount …

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The Determinants Of Locational Choice For Air Force Military Renters: Implications For Policy, Eldrick L. Hill Mar 1999

The Determinants Of Locational Choice For Air Force Military Renters: Implications For Policy, Eldrick L. Hill

Theses and Dissertations

Housing allowances and military family housing make up approximately $7 billion dollars of the budget for the Department of Defense (DoD). The military uses a Housing Market Analysis (HMA) to determine rental housing availability around its installations. This thesis describes and analyzes the locational choices of military renters. This thesis examines 16 bases in the continental U.S. using military and census data. It is concluded that the locational preferences of military renters vary inversely with distance from their duty location and this needs to be accounted for when assessing the availability of military rental housing. The implications of military renter …

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