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Theses and Dissertations

1997

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Institution
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Concept Vectors: A Synthesis Of Concept Mapping And Matrices For Knowledge Representation In Intelligent Tutoring Systems, Mark L. Dyson Dec 1997

Concept Vectors: A Synthesis Of Concept Mapping And Matrices For Knowledge Representation In Intelligent Tutoring Systems, Mark L. Dyson

Theses and Dissertations

A review of the literature relating to intelligent tutoring systems (ITS) reveals that the bulk of research to date is focused on the student, and on methods for representing the knowledge itself. From student models to learning schemas to presentation methods, comparatively little attention has been paid to the problem of educators attempting to build viable lesson plans for use in an ITS environment--yet when this problem is addressed in the literature, it is recognized as a potentially daunting one. This thesis addresses the problem of ITS lesson plan development by proposing a practical, computable approach for knowledge engineering that …

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An Investigation Of The Relationship Between Perception Levels Of Prime Beef Training And Readiness Task Confidence, D. Wade Lawrence Dec 1997

An Investigation Of The Relationship Between Perception Levels Of Prime Beef Training And Readiness Task Confidence, D. Wade Lawrence

Theses and Dissertations

This thesis examined the readiness training perception levels and task self-confidence of CE Prime BEEF personnel, and investigated the relationships between these two constructs. A heuristic model was developed which hypothesized that since previous research has shown that perception of training affects self-efficacy, and that self-efficacy affects performance, it may be inferred that training perception ultimately affects task performance. Surveys were sent to the target population to gather demographic data, perceptions of Prime BEEF readiness training and task confidence in both self and unit. Despite an improvement in perceptions over the past 12 years, results showed somewhat mediocre perception levels …

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An Analysis Of Early Software Reliability Improvement Techniques, John G. Leonard, Ric K. Nordgren Dec 1997

An Analysis Of Early Software Reliability Improvement Techniques, John G. Leonard, Ric K. Nordgren

Theses and Dissertations

This research explores early life cycle software reliability prediction models or techniques to predict the reliability of software prior to writing code, and a method for increasing or improving the reliability of software products early in the development life cycle. Five prediction models and two development techniques are examined. Each model is statically analyzed in terms of availability of data early in the life cycle, ease of data collection, and whether data is currently collected. One model and the two techniques satisfied those requirements and are further analyzed for their ability to predict or improve software reliability. While the researchers …

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An Investigation Of Plume Rise From Titan Iv Rocket Launches, Joseph D. Brands Dec 1997

An Investigation Of Plume Rise From Titan Iv Rocket Launches, Joseph D. Brands

Theses and Dissertations

Space launches at Cape Canaveral Air Station (CCAS) and Vandenberg Air Force Base (vAFB) produce exhaust ground clouds from the solid rocket boosters and liquid hypergolic fuels containing several toxic substances. In order to estimate the health effects that would be imposed upon the public by scheduled launches, range safety officials rely on the Rocket Exhaust Effluent Diffusion Model to predict ground level concentrations of these substances. A drawback to the REEDM is its underprediction of the initial ground clouds stabilization height. This underprediction causes an overprediction of the ground level toxic substance concentrations. This thesis focused on increasing the …

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Heavy Metal Toxicity In Bioremediation: Microbial Cultures And Microscopy, Jason B. Goodbody Dec 1997

Heavy Metal Toxicity In Bioremediation: Microbial Cultures And Microscopy, Jason B. Goodbody

Theses and Dissertations

This research employed a variety of microscopy and spread plating techniques to observe the effects of heavy metal treatments on a toluene-selected bacterial population. Microbial colonies were cultured on spread plates and the resulting numbers were compared to respiration data. The mechanisms of reproduction were demonstrated to be more sensitive to metal treatments than were the mechanisms of respiration. Phase contrast, Gram stain, fluorescent microscopy, were used to compare and document a wide variety of bacteria resulting from different metal treatments as well as from environmental changes within the source bioreactor. The removal of sensitive bacteria and the selection of …

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Optimized Design Methodology Of Cavity-Backed Microstrip Antennas With Dielectric Overlays, Douglas J. Hermes Dec 1997

Optimized Design Methodology Of Cavity-Backed Microstrip Antennas With Dielectric Overlays, Douglas J. Hermes

Theses and Dissertations

The optimized design methodology implemented in this research employs a design methodology, namely Response Surface Methodology (RSM), that is relatively new to the electromagnetics field. The design methodology used a full factorial designed experiment, a Hybrid Finite Element Method (HFEM) analysis code, a cubic spline empirical model, an Analysis of Variance (ANOVA) test, and a simplex optimization code to successfully measure, predict, analyze, and optimize average antenna gain and antenna input impedance for a cavity backed microstrip antenna with dielectric overlays. Based on HFEM results from the full factorial designed experiment, a cubic spline empirical model successfully predicted average antenna …

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Micro-Electromechanical Switches For Micro-Satellite Power Transfer, Glen A. Kading Dec 1997

Micro-Electromechanical Switches For Micro-Satellite Power Transfer, Glen A. Kading

Theses and Dissertations

In the past few years, microelectromechanical systems (MEMS) have emerged as a promising new technology with tremendous application potential. One of the possible implementations of MEMS technology is in the development of micro-satellites. It should be possible to mass-produce micro-satellites at a fraction of the cost of one conventional satellite. In order for satellites to be robust, a method of transferring power to systems must be addressed. As micro-satellites are made with conventional integrated circuit technologies at a very small scale, a means of transferring power on a similar scale will be investigated. This research addresses the issue of the …

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Mobilization Of Trace Elements In Aquifers By Biodegradation Of Hydrocarbon Contaminants, Scott L. Kearney Dec 1997

Mobilization Of Trace Elements In Aquifers By Biodegradation Of Hydrocarbon Contaminants, Scott L. Kearney

Theses and Dissertations

This study had two objectives: (1) to determine the extent of metal mobility within petroleum-contaminated aquifers, (2) to determine if biodegradation of petroleum hydrocarbons can explain metal mobility. The approach reviewed analytical results from 2305 groundwater sampling events, taken from 958 wells, located at 136 sites found at 53 Air Force installations. The study showed that high levels of metals are present at petroleum hydrocarbon sites where metals would not generally be expected. Of the metals with drinking water maximum contaminant levels (MCLs), mercury and silver were detected the least frequently. Barium and copper were detected at the sites, but …

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A Mammographic Registration Method Based On Optical Flow And Multiresolution Computing, Kevin A. Lee Dec 1997

A Mammographic Registration Method Based On Optical Flow And Multiresolution Computing, Kevin A. Lee

Theses and Dissertations

Mammography is a potent weapon in the fight against Breast Cancer, due in large part to its widespread availability and low cost. Despite the fact that mammography can detect small lesions as early as two years before they become palpable on physical exam, between 10 and 30 percent of cancerous lesions go undetected during evaluation by the radiologist. One approach to improving detection rates involves comparing mammograms of the same breast from successive years. Since most forms of breast cancer develop slowly, multiple view techniques might be able to detect subtle changes indicative of cancerous growth. This thesis proposes a …

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Requirements, Design And Prototype Of A Virtual User Interface For The Afit Virtual Spaceplane, John M. Lewis Dec 1997

Requirements, Design And Prototype Of A Virtual User Interface For The Afit Virtual Spaceplane, John M. Lewis

Theses and Dissertations

The United States Air Force is evaluating the feasibility of designing a military spaceplane capable of accomplishing military objectives from a low earth orbit and atmospheric flight regimes. Current efforts are involved in determining the scientific, operational, and budgetary constraints associated with this concept. This thesis looks at the exploration of new interface techniques associated with the design of a virtual spaceplane and is a subset of the overall virtual spaceplane effort which will assist researchers in determining the feasibility of a military spaceplane. Interface techniques are integrated into a virtual user interface that is designed to accommodate expected operations …

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Applying Flywheel Energy Storage To Solar Electric Orbital Transfers, Mark W. Marasch Dec 1997

Applying Flywheel Energy Storage To Solar Electric Orbital Transfers, Mark W. Marasch

Theses and Dissertations

This study investigated the application of flywheel energy storage to minimum time, constant thrust orbital maneuvers using electric propulsion. The advantages of using stored energy to continue electric thruster operations while in eclipse were explored. The boundary value problems for several schemes of energy use were examined, and numerical solutions were found. Results of simulations utilizing energy storage were compared to results without energy storage. Schemes incorporating energy storage were found to have advantages in terms of propellant mass used, time spent in transit, and deliverable payload.

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Information Superiority: Outsourcing An Air Force Core Competency?, Hugh J. Mcterman Dec 1997

Information Superiority: Outsourcing An Air Force Core Competency?, Hugh J. Mcterman

Theses and Dissertations

The information age is upon us. More businesses are relying on access to immediate and accurate information just to survive in the global marketplace. This reliance has caused most companies to take a closer look at what core business the firm is actually in, how information impacts those strategic areas, and how best to obtain the needed information. Joint Vision 2010 identifies information superiority as the foundation for joint war fighting doctrine and concepts moving toward the year 2010. This thesis explores the perceived relationship between the core competency requirements for information superiority and the tasks defined for the Air …

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Using Cross-Eye Techniques To Counter Radio Frequency Agile Monopulse Processing, Gregory J. Meyer Dec 1997

Using Cross-Eye Techniques To Counter Radio Frequency Agile Monopulse Processing, Gregory J. Meyer

Theses and Dissertations

The purpose of this research was to evaluate how current cross-eye techniques protect an airborne platform versus a pulse-to-pulse Radio Frequency (RF) agile monopulse processing threat and, if necessary, develop a new cross-eye techniques to counter this threat. This research evaluates how both current retrodirective cross-eye techniques and an original technique, namely synchronized cross-eye, hide the true skin return in the time and frequency domain while preserving the necessary phase interferometric effects at the threat radar location. Existing retrodirective cross-eye techniques are inadequate to counter the RF agile threat due to propagation delays. Using modeling and simulation, the research shows …

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Atmospheric Induced Errors In Space-Time Adaptive Processing, Vinod D. Naga Dec 1997

Atmospheric Induced Errors In Space-Time Adaptive Processing, Vinod D. Naga

Theses and Dissertations

This thesis examines the effects of atmospheric turbulence-induced phase perturbations on the performance of ground-based Space-Time Adaptive Processing (STAP) systems. Both Fully Adaptive Joint Domain Optimum and Partially Adaptive Factored-Time Space processing methods are examined. This thesis concentrates on the turbulence effects on STAP applied to ground-based arrays. This thesis further focuses on the capability of STAP to resolve targets at low elevation angles in the presence of turbulence. Only clutter interference and receiver noise are considered. Turbulence effects on the EM phase-front are calculated for turbulence strength Cn(2) values ranging from 5.0 x 10(exp -14) m-2/3 to 5.0 x …

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Scattering From Dielectric Bodies, Jeffery M. Parks Dec 1997

Scattering From Dielectric Bodies, Jeffery M. Parks

Theses and Dissertations

The purpose of this study was to develop an RCS measured database of non-PEC targets and provide an example of its use to validate a code, 3D-RCIE. RCS prediction codes that handle penetrable materials require measured data to determine their accuracy. The materials used for this research include polyethylene and polyurethane with dielectric constants around 2.3 and 1.03, respectively. The polyethylene targets include a mini-arrow, ogive, conesphere, conesphere with a gap, sphere, and a large and small cube. The cubes were the only targets made from the polyurethane foam. Additionally, r-card was applied to the cubes and mini-arrow. The material …

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Constrained Model Predictive Control Of A Nonlinear Aerospace System, Christopher M. Shearer Dec 1997

Constrained Model Predictive Control Of A Nonlinear Aerospace System, Christopher M. Shearer

Theses and Dissertations

Recent research efforts have applied the receding horizon Model Predictive Control (MPC) strategy to linearized high performance aerospace systems. The research contained in this thesis used these recent results in order to apply the MPC strategy to a nonlinear high performance aerospace system, specifically an F-16 fighter aircraft model. The model was commanded to follow dynamic trajectories of roll angle and altitude. Further, adaptive constraint techniques were used to improve system tracking. To accomplish these tasks, code and block diagrams were generated using the commercial software packages of Matlab and Simulink. Numerous simulations were conducted with the goal of achieving …

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An Examination Of Multi-Tier Designs For Legacy Data Access, Michael L. Acker Dec 1997

An Examination Of Multi-Tier Designs For Legacy Data Access, Michael L. Acker

Theses and Dissertations

This work examines the application of Java and the Common Object Request Broker Architecture (CORBA) to support access to remote databases via the Internet. The research applies these software technologies to assist an Air Force distance learning provider in improving the capabilities of its World Wide Web-based correspondence system. An analysis of the distance learning provider's operation revealed a strong dependency on a non-collocated legacy relational database. This dependency limits the distance learning provider's future web-based capabilities. A recommendation to improve operation by data replication is proposed, and the implementation details are provided for two alternative test systems that support …

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Pseudorandom Code Generation For Communication And Navigation System Applications, John F. Brendle Jr. Dec 1997

Pseudorandom Code Generation For Communication And Navigation System Applications, John F. Brendle Jr.

Theses and Dissertations

This research project investigated the design, construction and evaluation of a pseudorandom code generator for communication and navigation system applications. These types of codes include spreading codes, Gold codes, Jet Propulsion Laboratory (JPL) ranging codes, syncopated codes, and nonlinear codes. Such waveforms are typically used in communication and navigation system applications. The code generator uses the Stanford Telecom STEL-1032 Pseudorandom Number (PRN) coder. A coder interface was designed and constructed for manual data entry to the registers of the PRN coder. The code generator is capable of independently clocking and generating all possible codes with lengths up to 4,294,967,295 bits. …

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Modeling Uptake And Translocation Of Lead (Pb) In Maize For The Purposes Of Phytoextraction, Mark A. Brennan Dec 1997

Modeling Uptake And Translocation Of Lead (Pb) In Maize For The Purposes Of Phytoextraction, Mark A. Brennan

Theses and Dissertations

Phytoextraction is a remediation technology that uses plants to remove heavy metals from soil. This technology has the potential to decrease the costs of remediating contaminated sites by several orders of magnitude compared to traditional technologies. To effectively implement this technology requires an understanding of the plant processes that control uptake and translocation of metals from the soil. Currently these processes are poorly understood, and especially so for Pb. The purpose of this thesis was to gain insights concerning the plant mechanisms that control uptake and translocation of Pb and how these mechanisms interact to control levels of Pb accumulation …

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Orbit Estimation Using Track Compression And Least Squares Differential Correction, Vincent J. Chioma Dec 1997

Orbit Estimation Using Track Compression And Least Squares Differential Correction, Vincent J. Chioma

Theses and Dissertations

This thesis develops two methods of compressing a track of radar observations of a satellite into a single state vector and associated covariance matrix, and a method of estimating orbits using results from multiple tracks. The track compression uses least squares differential correction to determine a state vector at the central observation time. The resulting state vectors and covariance matrices are then used to estimate the satellite's orbit, also using least squares differential correction. Numerical integration using two-body, J2 and an atmospheric drag model is used to represent the dynamics. This orbit estimation produces a state vector which includes …

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Multiple Model Adaptive Estimation And Control Redistribution Performance On The Vista F-16 During Partial Actuator Impairments, Curtis S. Clark Dec 1997

Multiple Model Adaptive Estimation And Control Redistribution Performance On The Vista F-16 During Partial Actuator Impairments, Curtis S. Clark

Theses and Dissertations

Multiple Model Adaptive Estimation with Control Reconfiguration (MMAE/CR) capability to estimate and compensate for partial actuator failures, or "impairments" is investigated using the high-fidelity, nonlinear, six-degree-of-freedom, VISTA F-16 simulation which currently resides on the Simulation Rapid-Prototyping Facility (SRF). After developing a model for inserting partial actuator impairments into the VISTA F-16 truth model, research begins with a battery of single actuator impairment tests. This stage of research explores the capability of the existing MMAE algorithm to estimate single, partial actuator impairments, and helps to define refinements and expansions needed in the MMAE algorithm for the second phase of research: the …

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Organizational Support Of Internet Technology Infusion: An Exploratory Analysis., Anthony J. Davis Dec 1997

Organizational Support Of Internet Technology Infusion: An Exploratory Analysis., Anthony J. Davis

Theses and Dissertations

This thesis identifies managerial, organizational, and individual attributes which influence Internet technology infusion. Infusion can be defined as the incorporation of a technology into an organization's key processes. As infusion increases, the extended, integrative and emergent use of the technology increases, leading to increased leveraging of the technology. A survey was distributed to 1100 Air Force members throughout four Major Commands, divided into 600 officers and 500 enlisted. The analysis used Structural Equation Modeling to test models relating managerial, organizational and individual constructs as positive influences on infusion. Findings in the officer group indicate executive involvement and participation, policy, receptivity …

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Photoluminescence Study Of Gan Implanted With Erbium And Erbium-Oxygen, Lori R. Everitt Dec 1997

Photoluminescence Study Of Gan Implanted With Erbium And Erbium-Oxygen, Lori R. Everitt

Theses and Dissertations

Erbium emits at 1540 nm, which propagates well through fiber optic cables. This work studies the photoluminescence (PL) from GaN, GaN implanted with Er alone, and GaN implanted with both Er and O as functions of excitation laser energy and sample temperature. When the exciton bound to a neutral donor recombined, a photon was emitted at 3.47 eV. A photon emitted at 3.457 eV may have been evidence of the recombination of an exciton bound to a neutral acceptor. Second, the Er-ion transitions were observed in two groups around 0.805 and 1.25 eV. The PL intensity was measured at four …

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Pollution Prevention Process Influences In The Weapon System Acquisition Life Cycle, Tedmond B. Grady Dec 1997

Pollution Prevention Process Influences In The Weapon System Acquisition Life Cycle, Tedmond B. Grady

Theses and Dissertations

This research develops a system structure for the pollution prevention acquisition process and uses system dynamics modeling to develop management strategies that optimize life cycle cost. The structure of the pollution prevention acquisition process is developed by identifying primary influences and mechanisms and determining how they interact within the acquisition process. The model structure is based on the premise that rising total projected Life Cycle Cost (LCC) would provide an incentive to perform pollution prevention changes to reduce the overall LCC cost. The model successfully produces the expected reasonable behavior and confidence in the model structure is achieved using standard …

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Secondary Data Support And Non-Homogeneities In Space-Time Adaptive Processing, Todd B. Hale Dec 1997

Secondary Data Support And Non-Homogeneities In Space-Time Adaptive Processing, Todd B. Hale

Theses and Dissertations

One of the primary problems with the application of Space-Time Adaptive Processing (STAP) techniques is secondary data support for the interference plus noise covariance matrix estimate. Reed has shown the required secondary data support to achieve performance within 3 dB of optimal SINR is approximately equal to twice the degrees of freedom (DOF) used in the algorithm. Reed proved this rule for Sample Matrix Inversion (SMI) techniques. A concern arises when applying this rule to a newer class of reduced dimension STAP algorithms that do not fall under the SMI umbrella. This thesis focuses on the Cross Spectral Metric (CSM) …

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Development Of A System To Determine The Economically Optimal Combination Of Housing For An Air Force Installation, Johnathan E. Hendrix Dec 1997

Development Of A System To Determine The Economically Optimal Combination Of Housing For An Air Force Installation, Johnathan E. Hendrix

Theses and Dissertations

The United States Military is faced with the decision of how to house its military members and their families. The three options available to house these families are: 1) utilize existing on-base housing; 2) build new on-base housing; or, 3) compensate a military family monetarily to find housing off-base. This research focused on the development of a tool to all the decision maker in determining what combination of the three options is economically optimal for an individual Air Force Installation. The model developed incorporates the costs associated to the local area and conditions at the specific installation to determine the …

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Optimal Orbit Insertion Strategies Using Combined High And Low Thrust Propulsion Systems, Darren W. Johnson Dec 1997

Optimal Orbit Insertion Strategies Using Combined High And Low Thrust Propulsion Systems, Darren W. Johnson

Theses and Dissertations

Low thrust electric propulsion systems are becoming sufficiently mature to consider their use as primary propulsion for orbital transfer in place of high thrust chemical systems. Instead of facing an either/or situation, it may be advantageous to use both types. This effort demonstrates a technique for finding orbital transfer strategies that use both high and low thrust propulsion systems and which result in optimal tradeoffs of the performance parameters cost of orbit insertion, total orbit transfer time, and available spacecraft mass at final orbit. These performance parameters are calculated as a function of the fraction of orbit transfer from Low …

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User Location Determination Strategy In A Low Earth Orbit Satellite Network, Jaehee Lee Dec 1997

User Location Determination Strategy In A Low Earth Orbit Satellite Network, Jaehee Lee

Theses and Dissertations

Recently, many Low Earth Orbit (LEO) satellite systems have been proposed for the purpose of global communication and one of those systems is planned to start the commercial service in 1998. These LEO satellite systems are providing most of current communication services (voice, fax, data, paging, and even real time video service) without any limitation on place and time. However, little is published about their detail system methodology on user tracking and managing schemes. This thesis presents two user location tracking algorithms in a LEO environment. One (Gateway Approach) is the most likely approach under present system proposals, while the …

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An Examination Of Elements Necessary For Transfer Of An Environmental Remediation Technology From Full-Scale Demonstration To Implementation, Glenn C. Mandalas Dec 1997

An Examination Of Elements Necessary For Transfer Of An Environmental Remediation Technology From Full-Scale Demonstration To Implementation, Glenn C. Mandalas

Theses and Dissertations

The fact that an innovative environmental remediation technology has been proven feasible in a full scale evaluation does not assure that the technology will be implemented. A number of regulatory, economic, and institutional barriers may impede the transition of a remediation technology from full scale demonstration to implementation. This research explores these barriers, suggesting means to overcome them. Regulators, technology users, and other remediation decision makers apply the nine criteria specified in the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA) to evaluate the applicability of an innovative remediation technology at uncontrolled hazardous waste sites. These criteria consider such things …

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Ethical Issues In A Networked Environment, Kristen G. Sallberg Dec 1997

Ethical Issues In A Networked Environment, Kristen G. Sallberg

Theses and Dissertations

The research objective was to provide a preliminary understanding of how USAF computer users perceive the ethical considerations of computer networks and how the USAF is addressing ethical issues of networked environments. A survey was undertaken to explore questions of ethics in the use of information networks. The literature review explored issues of ethics in the private sector and USAF guidance regarding use of official government resources. The sample population consisted of military members stationed at Wright-Patterson Air Force Base Ohio. The responses regarding certain attitudes about behaviors and actions in a networked environment were consistent overall. A significant difference …

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