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Theses and Dissertations

Theses/Dissertations

1997

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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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The Rational Resolution Analysis: A Generalization Of Multi-Resolution Analyses With Application To To The Specific Emitter Identification Problem, Bruce P. Anderson Dec 1997

The Rational Resolution Analysis: A Generalization Of Multi-Resolution Analyses With Application To To The Specific Emitter Identification Problem, Bruce P. Anderson

Theses and Dissertations

The rational resolution analysis RRA is introduced and developed as a generalization of the integer, dilation multiresolution analyses MRA developed by Mallat and Meyer. Rational dilation factors are achieved by relaxing the condition on MRAs that successive approximation spaces be embedded. Conditions for perfect reconstruction are discussed and it is shown that perfect reconstruction is possible with specific constraints on the scaling function the scaling filter must have its roots on the unit circle. Furthermore, the required arrangement of the roots indicate the scaling function must be derived from a B-spline of some degree. It is proven the only compactly …

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An Incompleteness Handling Methodology For Validation Of Bayesian Knowledge Bases, David J. Bawcom Dec 1997

An Incompleteness Handling Methodology For Validation Of Bayesian Knowledge Bases, David J. Bawcom

Theses and Dissertations

The PESKI (Probabilities, Expert Systems, Knowledge, and Inference) system attempts to address some of the problems in expert system design through the use of the Bayesian Knowledge Base (BKB) representation. Knowledge gathered from a domain expert is placed into this framework and inferencing is performed over it. However, by the nature of BKBs, not all knowledge is incorporated, i.e. the representation need not be a complete representation of all combinations and possibilities of the knowledge, as this would be impractical in many real-world systems. Therefore, inherent in such a system is the problem of incomplete knowledge, or spaces within the …

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Developing A Corpus Specific Stoplist Using Quantitative Comparison, Craig N. Berg Dec 1997

Developing A Corpus Specific Stoplist Using Quantitative Comparison, Craig N. Berg

Theses and Dissertations

We have become overwhelmed with electronic information and it seems our situation is not going to improve. It is becoming increasingly common for people to work with information on a daily basis. We seem to spend more and more time looking for information, and it is taking longer because more information is available. This thesis will look at how we can provide faster access to the information we want to find. Today's requirements are closely related to searching for information using queries. At the heart of the query process is the removal of search terms having little or no significance …

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The Fate And Transport Of Airborne Jp-4 And Jp-8 Aerosol During Cold Startup, Bradford Eugene Buckman Dec 1997

The Fate And Transport Of Airborne Jp-4 And Jp-8 Aerosol During Cold Startup, Bradford Eugene Buckman

Theses and Dissertations

During cold startup (engine warm-up) procedures at northern tier bases, fuel aerosol (JP-4 and JP-8) is emitted before complete combustion of the fuel occurs. The time necessary for complete combustion to occur may be as long as 10 minutes. Hence, during these first few minutes, aerosol is emitted at relatively high concentrations. This research investigates the principle behavior of the emitted aerosol: advection, dispersion, evaporation, and settling. Using previous work in fuel jettisoning and evaporation as a foundation, this thesis investigates the physical factors affecting the airborne concentration of fuel aerosol at different times, the amount of fuel aerosol reaching …

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Microelectromechanical Scanner Using A Vertical Cavity Surface Emitting Laser, Joseph G. Bouchard Jr. Dec 1997

Microelectromechanical Scanner Using A Vertical Cavity Surface Emitting Laser, Joseph G. Bouchard Jr.

Theses and Dissertations

Optical scanners play a prominent role in the commercial and military industries. The scanner's size, cost and reliability are critical characteristics. In this research a microoptical scanning system was fabricated by incorporating a vertical cavity surface emitting laser (VCSEL) onto a surface machined microelectromechanical die. The micro optics for laser beam steering includes a 135 deg mirror, a Fresnel lens, a lateral scanning rotating mirror, and a vertical scanning fan mirror. The VCSEL was attached to the die by solder and electrical connection was provided by wire bonding. Based on far field measurements the scanner had a lateral scan angle …

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Visualization And Animation Of A Missile/Target Encounter, Jeffrey T. Bush Dec 1997

Visualization And Animation Of A Missile/Target Encounter, Jeffrey T. Bush

Theses and Dissertations

Existing missile/target encounter modeling and simulation systems focus on improving probability of kill models. Little research has been done to visualize these encounters. These systems can be made more useful to the engineers by incorporating current computer graphics technology for visualizing and animating the encounter. Our research has been to develop a graphical simulation package for visualizing both endgame and full fly-out encounters. Endgame visualization includes showing the interaction of a missile, its fuze cone proximity sensors, and its target during the final fraction of a second of the missile/target encounter. Additionally, this system displays dynamic effects such as the …

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Development And Validation Of An Experimental Test Rig For Electrohydrodynamic Enhancement Of Forced Convective Heat Transfer, William T. Caldwell Dec 1997

Development And Validation Of An Experimental Test Rig For Electrohydrodynamic Enhancement Of Forced Convective Heat Transfer, William T. Caldwell

Theses and Dissertations

This report details the development of a facility for the experimental investigation of electrohydrodynamic (EHD) enhancement of forced convection heat transfer. The test facility was developed for the Thermal and Transparencies Laboratory (TATLAB), Air Force Research Laboratory (AFRL), for use in future research into the applicability of EHD for the miniaturization of Air Force heat exchangers. During this research, a closed l6op, medium scale electrohydrodynamic test rig was developed and brought online. The test fluid loop was integrated with a data acquisition and parameter control system. Basic loop and fluid performance testing was accomplished through the use of a 3mm …

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Fatigue Behavior Of A Quasi-Isotropic Graphite/Epoxy Laminate Embedded With A Piezoelectric Sensor, Jon M. Coleman Dec 1997

Fatigue Behavior Of A Quasi-Isotropic Graphite/Epoxy Laminate Embedded With A Piezoelectric Sensor, Jon M. Coleman

Theses and Dissertations

This study primarily investigated the mechanical effects of embedding piezoelectric sensors on the tensile and fatigue strength of a quasi-isotropic, carbon-epoxy laminate. A secondary focus was the investigation of the sensor degradation under tensile loading. A [0 | ±45 | 90]s laminate was fabricated from Hercules AS4/3501-6 pre-preg tape. Specimens were first tested monotonically to obtain an average ultimate tensile strength and to detail the progression of damage. The fatigue tests were tension-tension, R=0.1, 10 Hz, constant amplitude. Results indicated that the embedded piezoelectric sensors did not have a significant effect on the tensile strength of the laminate. Specimens …

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The One With The Most Information Wins? The Quest For Information Superiority, Stacy M. Clements Dec 1997

The One With The Most Information Wins? The Quest For Information Superiority, Stacy M. Clements

Theses and Dissertations

The escalation of interest in information as a corporate resource is reflected in the military's quest for information superiority. A volume of directives, articles, and doctrine is appearing to meet the unique challenges presented by information as a resource. Discussions of how to achieve information superiority have given rise to investigations of such related concepts as information warfare and information operations, with associated taxonomies and ideas of how to use information capabilities for attack and defense. This thesis examines information superiority and the related concepts, and examines current information technology initiatives in order to discern the characteristics which can aid …

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Get Your Hands Out Of My Drawers: A Survey Of Information Ownership And Stewardship At The Air Force Institute Of Technology, Keith E. Kolekofski Jr. Dec 1997

Get Your Hands Out Of My Drawers: A Survey Of Information Ownership And Stewardship At The Air Force Institute Of Technology, Keith E. Kolekofski Jr.

Theses and Dissertations

Despite beliefs in the benefits of good Information Resources Management (IRM) practices, executives still find their organizations plagued by outdated, inconsistent, and unavailable information. This information is often stored in disparate, standalone systems spread throughout the business. The Air Force Institute of Technology (AFIT) fails to reap the synergistic benefits of shared information despite its bounty of information systems and proclamations for IRM principles. Previous researcher postulated that this disconnect may be explained, in part, by an ownership attitude at the functional level. Empirical evidence gathered from a survey of AFIT's members failed to support Plant's hypothesis. Exploratory factor analysis …

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Usaf Pilot Perceptions Of Workload Assessment In A Combat Or High-Threat Environment, Kadircan Kottas Dec 1997

Usaf Pilot Perceptions Of Workload Assessment In A Combat Or High-Threat Environment, Kadircan Kottas

Theses and Dissertations

This study analyzed the self-reported survey responses of 219 Air Force Pilots concerning their perceptions of workload assessment in a combat or a high threat environment. The first objective of this study was to determine and compare the combat workload factors of varying importance in combat workload assessment by aircraft and mission type flown. The second objective was to examine the pilots' perception of combat mission inflight workload. A stepwise regression model to predict the pilots' perceptions of inflight workload using pilots' characteristics data was explored. Research conclusion varied among aircraft types. Combat workload items indicated as distractingly important were …

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Creating Origen Models, Gregory D. Louden Dec 1997

Creating Origen Models, Gregory D. Louden

Theses and Dissertations

The purpose of this study was to develop a methodology for creating problem dependent cross section libraries for ORIGEN (Oak Ridge Isotope Generation and Depletion Code). The Air Force Technical Applications Center (AFTAC) has a requirement to classify spent nuclear fuel. The ORIGEN codes provide generic models of commercial nuclear reactor designs that are not adequate for the detailed analysis required by AFTAC. After comparing the methods that ORIGEN2 an ORIGEN-S use to develop burnup dependent cross section libraries, the research focused on developing a methodology for creating new ORIGEN-S models. Models of the Ohio State University Research Reactor were …

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A Reconfigurable Superscalar Architecture, Christopher B. Mayer Dec 1997

A Reconfigurable Superscalar Architecture, Christopher B. Mayer

Theses and Dissertations

The invention of the Field Programmable Gate Array (FPGA) has led to a number of interesting developments. One is the idea of providing custom hardware support for applications running on a computer. These reconfigurable computers have been shown to decrease the execution time for some applications. Based on past results, attention has subsequently turned to using reconfigurable computing in general-purpose computers (e.g. desktop and workstation environments). This thesis develops a design for just such a computer. The design, FPGADLX, is based on a hypothetical superscalar computer running the DLX instruction set and is generic enough in principle to be adapted …

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Cepstral Processing For Gps Multipath Detection And Mitigation, Charles D. Ormsby Dec 1997

Cepstral Processing For Gps Multipath Detection And Mitigation, Charles D. Ormsby

Theses and Dissertations

This work presents a novel approach to code phase multipath mitigation for Global Positioning System (GPS) receivers. It uses the power and complex cepstra for multipath detection and mitigation prior to code phase tracking by a standard non-coherent delay lock loop. Cepstral theory is presented to demonstrate how multipath reflection delays can be detected through the use of the power cepstrum. Filtering can then be performed on the complex cepstrum to remove multipath effects in the cepstral domain. Finally, an inverse complex cepstrum is calculated yielding a theoretically multipath free direct path estimate in the time domain. Simulations are presented …

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Speaker Verification In The Presence Of Channel Mismatch Using Gaussian Mixture Models, Robert B. Reid Dec 1997

Speaker Verification In The Presence Of Channel Mismatch Using Gaussian Mixture Models, Robert B. Reid

Theses and Dissertations

A channel compensation method is sought for use in speaker identification (ID) and verification applications under matched and mismatched training and testing conditions. This work expands on previous work on matched conditions by investigating three techniques on matched and mismatched conditions using the TIMIT and NTIMIT speech databases. First, previous results on 168 speakers are reproduced for matched conditions using Gaussian mixture models (GMM) and mel-frequency cepstral coefficients. Next, cepstral mean subtraction with band limiting (CMSBL) is investigated. The third method, developed in this thesis uses a modified Wiener filtering approach to channel compensation. New GMMs are created for each …

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A Wire Antenna Designed For Space Wave Radiation Over The Earth Using A Genetic Algorithm, Brian S. Sandlin Dec 1997

A Wire Antenna Designed For Space Wave Radiation Over The Earth Using A Genetic Algorithm, Brian S. Sandlin

Theses and Dissertations

A wire antenna is designed for optimal performance at low elevation angles in the presence of a lossy half-space. A simple genetic algorithm (GA) and GENOCOP III software are each integrated with Numerical Electromagnetics Code Version 4.1 (NEC4.1) to optimize a wire antenna geometry for multiple objectives: power gain, azimuthal symmetry, and input impedance. The performance of the two versions of the integrated GA are compared. Several of the resulting antennas are analyzed, and an antenna is proposed for use in a Remote Intrusion Monitoring System (RIMS). Simulations suggest that the proposed antenna, which is well-matched, offers a significant increase …

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Information Resource Management: An Analysis Of The Critical Skills, Training Sources, And Training Adequacy As Perceived By Air Force Communications And Information Officers, Donald A. Schmidt Dec 1997

Information Resource Management: An Analysis Of The Critical Skills, Training Sources, And Training Adequacy As Perceived By Air Force Communications And Information Officers, Donald A. Schmidt

Theses and Dissertations

This study explores what Information Resource Management (IRM) skills are required as perceived by the Air Force officers performing IRM duties. The following questions set the stage for this research: (1) What does current literature say about the required skills needed for IRM professionals? (2) What IRM skills do officers in the field perceive as important to the IRM mission? (3) What is the primary source of any IRM training received by the officers? (4) How adequate was this training, if any? The results suggest that Air Force officers have a grasp of IRM concepts and know what skills are …

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An Analysis Of The Use Of Social Processes During Computer Use, Shawna R. Wimpy Dec 1997

An Analysis Of The Use Of Social Processes During Computer Use, Shawna R. Wimpy

Theses and Dissertations

This study investigated the claim that people use social processes relating to other humans when interacting with computers. A laboratory study (n = 38) manipulated two team factors, identity and interdependence and a stereotype activation effect to two labels, generalist and specialist. Subjects for this study were military members or civilians working for the military. The results show that none of the subjects reported being influenced by team or stereotype manipulations as given in self-reports. Incongruent to these findings, the behavioral data demonstrated that subjects were influenced by stereotype labels. There were no interaction effects between team factors and stereotype …

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A System Dynamics Model Of The Bioavailability Of Metals In Constructed Wetland Sediment, Timothy S. Wood Dec 1997

A System Dynamics Model Of The Bioavailability Of Metals In Constructed Wetland Sediment, Timothy S. Wood

Theses and Dissertations

Constructed wetlands used for storm water treatment accumulate metals primarily in their sediment. This sediment has the potential to produce toxic effects in benthic organisms at some period in time. Bioavailability of metals in sediment is directly linked to pore water metal activity. The mechanisms that influence pore water metal activity are included in physical, chemical, and biological processes. A system dynamics model was developed to represent these processes and the major influences affecting pore water metal activity in a treatment wetland receiving storm water influent. The model structure and behavior was tested and validated using several system dynamics validation …

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Reactive Quantum Scattering In Two Dimensions, Roy S. Calfas Dec 1997

Reactive Quantum Scattering In Two Dimensions, Roy S. Calfas

Theses and Dissertations

In an effort to develop a more efficient time dependent approach for calculating scattering matrix elements, absorbing boundary conditions are combined together with the channel packet method. As an introduction to scattering, scattering matrix elements are presented for a one-dimensional square well and a one-dimensional potential consisting of a Gaussian well with symmetric Gaussian barriers. Next, the combination of the channel packet method together with absorbing boundary conditions yields an order of magnitude savings in the time necessary to compute the correlation function for the collinear H+H

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The Virtual Spaceplane: Integrating Multiple Motion Models And Hypertext In A Virtual Environment, Troy Johnson Dec 1997

The Virtual Spaceplane: Integrating Multiple Motion Models And Hypertext In A Virtual Environment, Troy Johnson

Theses and Dissertations

The Air Force is currently investigating the possibility of developing a manned vehicle capable of operating in space. This Military Spaceplane (MSP) will be capable of ascent to low-earth orbit and maneuvering while in orbit. The goal of this research involved creating the Virtual Spaceplane (VSP), a virtual environment (VE) simulator for the MSP. This thesis examines two ideas significant to virtual environments and cockpit design: multiple motion models and hypertext in a VE. Movement in a VE has traditionally been modeled using a single motion model. Little work has been done to allow a change of the motion model …

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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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Metabolic Inhibition Of A Toluene-Enriched Microbial Population Due To Lead (Pb2+): Verification Of A Free Metal Ion Toxicity Model, Patrick J. S. Marbas Dec 1997

Metabolic Inhibition Of A Toluene-Enriched Microbial Population Due To Lead (Pb2+): Verification Of A Free Metal Ion Toxicity Model, Patrick J. S. Marbas

Theses and Dissertations

A dissolved oxygen probe and an ion specific electrode were used to study the lead-induced metabolic inhibition in a toluene-enriched microbial population. Predicted toxicity values were compared to the actual toxicity responses using a free metal ion toxicity model (TM) which linked metabolic inhibition with lead activity. Experimentally derived values for the model parameters (lead activity and a lead distribution coefficient) were used in the TM. It was postulated that cellular metabolism is disrupted by the conformational changes to the cell's plasma membrane produced by lead ion adsorption. The predicted toxicity values were higher than the actual toxicity response. This …

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Fpga Processor Implementation For The Forward Kinematics Of The Umdh, Steven M. Parmley Dec 1997

Fpga Processor Implementation For The Forward Kinematics Of The Umdh, Steven M. Parmley

Theses and Dissertations

The focus of this research was on the implementation of a forward kinematic algorithm for the Utah MIT Dexterous Hand (UMDH). Specifically, the algorithm was synthesized from mathematical models onto a Field Programmable Gate Array (FPGA) processor. This approach is different from the classical, general purpose microprocessor design where all robotic controller functions including forward Kinematics are executed serially from a compiled programming language such as C. The compiled code and subsequent real time operating system must be stored on some form of nonvolatile memory, typically magnetic media such as a fixed or hard disk drive, along with other computer …

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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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Spontaneous Emission In Microcavity Lasers, Dustin Philip Ziegler Dec 1997

Spontaneous Emission In Microcavity Lasers, Dustin Philip Ziegler

Theses and Dissertations

An understanding of spontaneous emission processes within microcavities is crucial in addressing the need to make tomorrow's microlasers more efficient. One approach to improving the device efficiency is to reduce the threshold input energy at which lasing begins to occur. It has been suggested that the threshold in a microcavity laser can be decreased by increasing the fraction of spontaneous emission into the lasing mode, this can be accomplished by preferentially coupling the gain medium of the laser to the electromagnetic cavity mode of interest. It therefore becomes necessary to understand the mechanism by which this coupling takes place. This …

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