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Theses/Dissertations

Air Force Institute of Technology

1996

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An Object-Oriented Discrete-Event Simulation System For Hierarchical Parallel Simulations, Kenneth W. Stauffer Dec 1996

An Object-Oriented Discrete-Event Simulation System For Hierarchical Parallel Simulations, Kenneth W. Stauffer

Theses and Dissertations

The purpose of this research is to design and implement an object-oriented discrete-event simulation system which supports hierarchically constructed players in a parallel or distributed environment. This system design considers modularity and portability so additional modules may be implemented to experiment with new algorithms for both partitioning and synchronization. A simulation system which meets these requirements was partially implemented on an eight-node Intel Hypercube in C. A desired goal was to maintain the functionality of the existing BattleSim application. Test cases used measure the performance and correct operation of the new simulation architecture using a BattleSim subclass. Test results prove …

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Student Modeling In An Intelligent Tutoring System, Jeremy E. Thompson Dec 1996

Student Modeling In An Intelligent Tutoring System, Jeremy E. Thompson

Theses and Dissertations

This thesis explores a new approach to modeling the student in an intelligent tutoring system (ITS), by providing a student model which learns new solutions from the student. A prototype of the new approach to ITS is demonstrated in the Euclidean geometry domain. Complete C++, CLIPS, and Tcl/Tk code listings are included in the appendices for reference. Adaptable multiple software agents were targeted for implementation, based on current literature. However, the student model is found to be maintainable without multiple software agents, while still allowing for tracking several possible solution paths when monitoring student solutions. This capability contradicts previous research …

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On Unifying Time And Uncertainty: The Probabilistic Temporal Network, Joel D. Young Dec 1996

On Unifying Time And Uncertainty: The Probabilistic Temporal Network, Joel D. Young

Theses and Dissertations

Complex real-world systems consist of collections of interacting processes/events. These processes change over time in response to both internal and external stimuli as well as to the passage of time. Many domains such as real-time systems diagnosis, (mechanized) story understanding, planning and scheduling, and financial forecasting require the capability to model complex systems under a unified framework to deal with both time and uncertainty. Existing uncertainty representations and existing temporal models already provide rich languages for capturing uncertainty and temporal information, respectively. Unfortunately, these partial solutions have made it extremely difficult to unify time and uncertainty in a way that …

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Modeling And Simulation Of Optical Characteristics Of Microelectromechanical Mirror Arrays, Peter C. Roberts Dec 1996

Modeling And Simulation Of Optical Characteristics Of Microelectromechanical Mirror Arrays, Peter C. Roberts

Theses and Dissertations

MEMS (Micro-Electro-Mechanical Systems) micromirror devices can be used to control the phase of a propagating light wavefront, and in particular to correct aberrations that may be present in the wavefront, due to either atmospheric turbulence or any other type of fixed or time and space varying aberrations. In order to shorten the design cycle of MEMS micromirror devices, computer software is developed to create, from MEMS micromirror device design data, a numerical model of the MEMS device. The model is then used to compute the far field diffraction pattern of a wavefront reflected from the device, and to predict the …

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Pulse Coupled Neural Networks For The Segmentation Of Magnetic Resonance Brain Images, Shane L. Abrahamson Dec 1996

Pulse Coupled Neural Networks For The Segmentation Of Magnetic Resonance Brain Images, Shane L. Abrahamson

Theses and Dissertations

This research develops an automated method for segmenting Magnetic Resonance (MR) brain images based on Pulse Coupled Neural Networks (PCNN). MR brain image segmentation has proven difficult, primarily due to scanning artifacts such as interscan and intrascan intensity inhomogeneities. The method developed and presented here uses a PCNN to both filter and segment MR brain images. The technique begins by preprocessing images with a PCNN filter to reduce scanning artifacts. Images are then contrast enhanced via histogram equalization. Finally, a PCNN is used to segment the images to arrive at the final result. Modifications to the original PCNN model are …

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An Incremental Language Conversion Method To Convert C++ Into Ada95, Ding-Yuan Sheu Dec 1996

An Incremental Language Conversion Method To Convert C++ Into Ada95, Ding-Yuan Sheu

Theses and Dissertations

This thesis develops a methodology to incrementally convert a legacy object oriented C++ application into Ada95. Using the experience of converting a graphic application, called Remote Debriefing Tool (RDT), in the Graphics Lab of the Air Force Institute of Technology (AFIT), this effort defined a process to convert a C++ application into Ada95. The methodology consists of five phases: (1) reorganizing the software application, (2) breaking mutual dependencies, (3) creating package specifications to interface the existing C++ classes, (4) converting C++ code into Ada programs, and (5) embellishing. This methodology used the GNAT's C++ low level interface capabilities to support …

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Whose Information Is It Anyway? An Argument For Information Stewardship, Trevor W. Plant Dec 1996

Whose Information Is It Anyway? An Argument For Information Stewardship, Trevor W. Plant

Theses and Dissertations

Information is an important resource for businesses and government, with information quality influencing decision quality, and highlighting our need to manage our information well: as a resource. Information Resource Management (IRM) has as its goal the management of information as a resource, but has not been implemented with the level of success expected. Problems with the implementation of IRM are indicated by the presence of redundant or inconsistent data, inability to share information across systems, and difficulty finding the information on systems. We propose that these difficulties are related to behaviours linked to perceived ownership of corporate information by organisational …

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Data-Driven Process Discovery: A Discrete Time Algebra For Relational Signal Analysis, David M. Conrad Dec 1996

Data-Driven Process Discovery: A Discrete Time Algebra For Relational Signal Analysis, David M. Conrad

Theses and Dissertations

This research presents an autonomous and computationally tractable method for scientific process analysis, combining an iterative algorithmic search and a recognition technique to discover multivariate linear and non-linear relations within experimental data series. These resultant data-driven relations provide researchers with a potentially real-time insight into experimental process phenomena and behavior. This method enables the efficient search of a potentially infinite space of relations within large data series to identify relations that accurately represent process phenomena. Proposed is a time series transformation that encodes and compresses real-valued data into a well-defined, discrete-space of 13 primitive elements where comparative evaluation between variables …

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Inference Algorithm Performance And Selection Under Constrained Resources, Brett J. Borghetti Dec 1996

Inference Algorithm Performance And Selection Under Constrained Resources, Brett J. Borghetti

Theses and Dissertations

Knowing that reasoning over probabilistic networks is, in general, NP-hard, and that most reasoning environments have limited resources, we need to select algorithms that can solve a given problem as fast as possible. This thesis presents a method for predicting the relative performance of reasoning algorithms based on the domain characteristics of the target knowledge structure. Armed with this knowledge, the research shows how to choose the best algorithm to solve the problem. The effects of incompleteness of the knowledge base at the time of inference is explored, and requirements for reasoning over incompleteness are defined. Two algorithms for reasoning …

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An Investigation Of Instantaneous Plume Rise From Rocket Exhaust, Paul F. Sand Dec 1996

An Investigation Of Instantaneous Plume Rise From Rocket Exhaust, Paul F. Sand

Theses and Dissertations

Rocket launches at Vandenburg Air Force Base and Cape Canaveral Air Station produce exhaust clouds containing several toxic by-products, including HC1 and A12O3. These clouds rise to atmospheric stabilization heights, and then start dispersing and diffusing through the air. Upon reaching the ground, concentration levels of the toxins may present a human health risk. To predict these risks and concentration levels, range officials use a computer program titled the Rocket Effluent Exhaust Diffusion Model (REEDM). The version currently in use has been shown to underpredict the stabilization height of the exhaust cloud. This thesis examines the theory and algorithms used …

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Analysis And Simulation Of A New Code Tracking Loop For Gps Multipath Mitigation, Mark C. Laxton Dec 1996

Analysis And Simulation Of A New Code Tracking Loop For Gps Multipath Mitigation, Mark C. Laxton

Theses and Dissertations

This thesis proposes a new direct sequence spread spectrum (DS/SS) code phase tracking loop which mitigates the effects of multipath interference on code phase tracking error; such errors can translate to significant range measurement errors in DS/SS ranging systems such as Global Positioning System (GPS). The new code tracking loop, called the modified RAKE delay lock loop (MRDLL), uses maximum likelihood (ML) signal parameter estimation to determine the amplitude, carrier phase, and relative propagation delay of both a direct path and a reflected signal; a multiple correlator code phase tracking loop then exploits these ML signal estimates to remove the …

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Estimation Of Satellite Orientation From Space Surveillance Imagery Measured With An Adaptive Optics Telescope, Gregory E. Wood Dec 1996

Estimation Of Satellite Orientation From Space Surveillance Imagery Measured With An Adaptive Optics Telescope, Gregory E. Wood

Theses and Dissertations

The use of the matched filter to automatically estimate the pose of a Low Earth Orbiting satellite from imagery taken with an adaptive optics telescope is explored. This work represents the first effort to solve the satellite pose estimation problem while considering the broad range of atmospheric turbulence levels and target visual magnitudes that are encountered in ground based space surveillance operations. Several Algorithms are examined in an effort to determine the performance bounds on the matched filter for this application. Results are given over an extremely wide range of seeing conditions. These results are weighted based on historical data …

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Exploring The Policy Issues Of Electronic Freedom Of Information Act Requests Through The Use Of The Government Information Locator Service, Lori A. Rogers Dec 1996

Exploring The Policy Issues Of Electronic Freedom Of Information Act Requests Through The Use Of The Government Information Locator Service, Lori A. Rogers

Theses and Dissertations

This study provides a preliminary view of the policy issues involved with allowing electronic Freedom of Information Act (FOIA) requests through the use of the Government Information Locator Service. The author used an exploratory, qualitative methodology consisting of an extensive literature review and a self-administered questionnaire that was sent to 54 Air Force (AF) FOIA managers. The literature review revealed that an informed citizenry is critical to a democratic society. To ensure its citizens have the opportunity to stay informed, Congress has enacted and amended laws to protect public access to federal information. The primary benefits of electronic FOIA requests …

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Automated Document Conversion: A Manager's Perspective, Fredrick W. Knaak Iii Dec 1996

Automated Document Conversion: A Manager's Perspective, Fredrick W. Knaak Iii

Theses and Dissertations

Technological advances in our workplaces have made electronic documents pervasive throughout the USAF, DoD, and civilian world. Managers are recognizing the need to establish electronic document management systems to handle these diverse forms of documents. Unfortunately, they have been faced with essentially "reinventing the wheel," when it comes to determining which types of paper-based documents are best suited to conversion to an electronic format. There is also a lack of clearly identifiable cost factors associated with automated document conversion (ADC) for managers to use when conducting an economic analysis of a potential imaging application. This thesis addresses the problem of …

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Microelectromechanical Isolation Of Acoustic Wave Resonators, James R. Reid Jr. Dec 1996

Microelectromechanical Isolation Of Acoustic Wave Resonators, James R. Reid Jr.

Theses and Dissertations

Microelectromechainical systems (MEMS) is a rapidly expanding field of research into the design and fabrication of actuated mechanical systems on the order of a few micrometers to a few millimeters. MEMS potentially offers new methods to solve a variety of engineering problems. A large variety of MEMS systems including flip-up platforms, scanning micromirrors, and rotating micromirrors are developed to demonstrate the types of MEMS that can be fabricated. The potential of MEMS for reducing the vibration sensitivity of surface acoustic wave and surface transverse wave resonators is then evaluated. A micromachined vibration isolation system is designed and modeled. A fabrication …

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Countering The Effects Of Measurement Noise During The Identification Of Dynamical Systems, Odell R. Reynolds Dec 1996

Countering The Effects Of Measurement Noise During The Identification Of Dynamical Systems, Odell R. Reynolds

Theses and Dissertations

Sensor noise is an unavoidable fact of life when it comes to measurements on physical systems, as is the case in feedback control. Therefore, it must be properly addressed during dynamic system identification. In this work, a novel approach is developed toward the treatment of measurement noise in dynamical systems. This approach hinges on proper stochastic modeling, and it can be adapted easily to many different scenarios, where it yields consistently good parameter estimates. The Generalized Minimum Variance algorithm developed and used in this work is based on the theory behind the minimum variance identification process, and the estimate produced …

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Multidisciplinary And Multiobjective Optimization In Conceptual Design For Mixed-Stream Turbofan Engines, Luc J. J. P. Nadon Dec 1996

Multidisciplinary And Multiobjective Optimization In Conceptual Design For Mixed-Stream Turbofan Engines, Luc J. J. P. Nadon

Theses and Dissertations

Despite major advances in design tools such as engine cycle analysis software and computer aided design, conceptual gas turbine engine design is essentially a trial-and-error process based on the experience of engineers. Modern optimization concepts, such as multidisciplinary optimization (MDO), and multiobjective optimization (MOO), linked with sequential quadratic programming (SQP) methods and genetic algorithms (GA), were applied to the conceptual engine design process to automate the conceptual design phase. Robust integrated computer codes were created to find the optimal values of eight engine parameters in order to minimize fuel usage, aircraft cost and engine annulus area over a given mission. …

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Residual Strength And Fatigue Characterization Of Scs-6/Ti-6-4, Sang-Myung Lee Dec 1996

Residual Strength And Fatigue Characterization Of Scs-6/Ti-6-4, Sang-Myung Lee

Theses and Dissertations

Metal matrix composite have potential in a variety of aerospace applications, but they should be better understood before they can be employed. Despite the many studies that have contributed to characterizing the fatigue response of titanium alloy MMCs, few have researched the residual strength. The purpose of this study was to investigate the residual strength and the frequency effects on the residual strength of an unidirectional laminate of SCS-6/Ti-6-4, a titanium alloy matrix based composite under tension-tension, load-controlled conditions at elevated temperatures and different frequencies. Specimens were fatigued at frequencies of 1 and 0.01Hz, and at maximum stress of 900MPa …

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Demonstrating Optical Aberration Correction With A Mems Micro-Mirror Device, Shaun R. Hick Dec 1996

Demonstrating Optical Aberration Correction With A Mems Micro-Mirror Device, Shaun R. Hick

Theses and Dissertations

This research conducted the first demonstrated use of a micro-electro-mechanical structure (MEMS) mirror array to correct a static optical aberration. A well-developed technique in adaptive optics imaging systems uses a deformable mirror to reflect the incident wave front to the imaging stage of the system. By matching the surface of the deformable mirror to the shape of the wave front phase distortion, the reflected wave front will be less aberrated before it is imaged. Typical adaptive optics systems use piezo-electric actuated deformable mirrors. This research used an electrostatically actuated, segmented mirror array, constructed by standard MEMS fabrication techniques, to investigate …

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Refined Genetic Algorithms For Polypeptide Structure Prediction, Charles E. Kaiser Jr. Dec 1996

Refined Genetic Algorithms For Polypeptide Structure Prediction, Charles E. Kaiser Jr.

Theses and Dissertations

Accurate and reliable prediction of macromolecular structures has eluded researchers for nearly 40 years. Prediction via energy minimization assumes the native conformation has the globally minimal energy potential. An exhaustive search is impossible since for molecules of normal size, the size of the search space exceeds the size of the universe. Domain knowledge sources, such as the Brookhaven PDB can be mined for constraints to limit the search space. Genetic algorithms (GAs) are stochastic, population based, search algorithms of polynomial (P) time complexity that can produce semi-optimal solutions for problems of nondeterministic polynomial (NP) time complexity such as PSP. Three …

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A Test-Case Based Approach To Bayesian Knowledge Base Incompleteness Detection And Correction, Louise J. Lyle Dec 1996

A Test-Case Based Approach To Bayesian Knowledge Base Incompleteness Detection And Correction, Louise J. Lyle

Theses and Dissertations

This work develops tools and techniques to identify particular Bayesian Knowledge Base (BKB) incompletenesses, and to modify the existing knowledge-base (KB) structure to correct these problems. The methodology performs manually or automatically, informing the user of either problems causing the incompleteness, or of details resulting from the automatic knowledge-base correction. The proposed methodology is designed for integration with BVAL, to augment BVAL's validation techniques.

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Integrating The Capability Maturity Model For Software And The Quality Air Force Criteria, Marshall B. Messamore Dec 1996

Integrating The Capability Maturity Model For Software And The Quality Air Force Criteria, Marshall B. Messamore

Theses and Dissertations

As defense budgets decrease and it is required to do more with less, the Air Force has chosen to use the Malcolm Baldrige National Quality Award (MBNQA) as the basis for implementing quality principles. The Air Force program is known as Quality Air Force (QAF), and the criteria are referred to as the QAF criteria DEPA95b. At about the same time the Department of the Air Force implemented QAF, the software leaders in the Air Force adopted the Capability Maturity Model for Software (CMM) as the internal standard for Air Force software organizations MOSE9l. Software organizations strapped with both sets …

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Dynamic Relevance Filtering In Asynchronous Transfer Mode-Based Distributed Interactive Simulation Exercises, David T. Hightower Dec 1996

Dynamic Relevance Filtering In Asynchronous Transfer Mode-Based Distributed Interactive Simulation Exercises, David T. Hightower

Theses and Dissertations

As Distributed Interactive Simulation (DIS) exercises continue to grow in scale, the need to support a large number of players has become apparent. The demands on the network and the simulation hosts in large exercises, though, have proved to be prohibitive, requiring significant computational overhead to filter through the information and extract what is relevant to a particular simulation. Some mechanism is needed to reduce irrelevant network traffic received by a system, while increasing the bandwidth available for the DIS exercise. Previous research efforts in this area have centered primarily on fixed geographic partitions of the battlespace to reduce the …

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Collaborative Workspaces Within Distributed Virtual Environments, William D. Wells Dec 1996

Collaborative Workspaces Within Distributed Virtual Environments, William D. Wells

Theses and Dissertations

In warfare, be it a training simulation or actual combat, a commander's time is one of the most valuable and fleeting resources of a military unit. Thus, it is natural for a unit to have a plethora of personnel to analyze and filter information to the decision-maker. This dynamic exchange of ideas between analyst and commander is currently not available within the distributed interactive simulation (DIS) community. This lack of exchange limits the usefulness of the DIS experience to the commander and his troops. This thesis addresses the commander's isolation problem through the integration of a collaborative workspace within AFIT's …

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A Software Architecture For Computer Generated Forces In Complex Distributed Virtual Environments, Vincent B. Zurita Dec 1996

A Software Architecture For Computer Generated Forces In Complex Distributed Virtual Environments, Vincent B. Zurita

Theses and Dissertations

Complex Distributed Virtual Environments (DVEs) present an outstanding opportunity for the Department of Defense to train geographically separated units within a single realistic threat environment with minimal logistical considerations or safety concerns. To increase the fidelity of these simulations, minimize cost, and thereby maximize the training potential, DVEs must be populated with a realistic number of Computer Generated Forces (CGFs). These are currently expensive to design and build due to a lack of standard COF architectures. A solution to this problem is presented in the form of a CGF Architecture that is applicable to CGFs that model any weapon system. …

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A Decision Support Model For Municipal Solid Waste Recycling At United States Air Force Installations, Gergory A. Williams Dec 1996

A Decision Support Model For Municipal Solid Waste Recycling At United States Air Force Installations, Gergory A. Williams

Theses and Dissertations

The United States Air Force requires each installation to operate a municipal solid waste recycling program. Two inherently conflicting objectives, waste material diversion and financial result, have been established for the program. Reducing landfill disposal is the primary objective, but the incentive for profit is strong because each installation can retain profits from the program. Installations can be divided into two distinct areas, commercial and residential, based on the waste stream composition and funding. Structuring of the recycling program is often done in an ad-hoc manner. A decision support model was developed to evaluate four methods for each area. The …

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Modeling Plant Uptake Of Metal In Constructed Wetlands Supported By Experimentally Derived Uptake Rates, Michael B. Peake Dec 1996

Modeling Plant Uptake Of Metal In Constructed Wetlands Supported By Experimentally Derived Uptake Rates, Michael B. Peake

Theses and Dissertations

Many communities and Air Force installations are using constructed wetlands to filter trace metals from their stormwater runoff. Constructed wetlands are attractive to industry for runoff mitigation because they are relatively cheap to build and operate and require little or no energy for operation. The purpose of this research project is to develop quantitative concepts for understanding the dynamics of metal uptake in constructed wetland plants by constructing a system dynamics model supported by experimental observation and offer environmental managers a tool to simulate, under a broad range of conditions, long term wetland exposure to stormwater runoff contaminated with trace …

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Evaluating The Hazardous Materials (Hazmat) Pharmacy Among Air Force Majcoms Using Waste Reductions And Activity Indicators, W. Edward Iseman Jr. Dec 1996

Evaluating The Hazardous Materials (Hazmat) Pharmacy Among Air Force Majcoms Using Waste Reductions And Activity Indicators, W. Edward Iseman Jr.

Theses and Dissertations

The Hazardous Materials (HazMat) Pharmacy has been designed as an environmentally friendly vehicle to handle, store, dispense, track, recycle, and dispose of hazardous materials in the Air Force. This thesis effort proposed a method in which valuable feedback for the pharmacy can be obtained. Because it is still in the early stages of implementation, there has been little feedback on the pharmacy. An activity index that uses a variable most closely associated with the generation of hazardous waste in a MAJCOM is proposed. Using an aircraft maintenance related variable, like maximum take-off weight, the fluctuations in mission over time can …

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Adaptive Neural Network Controller For Atm Traffic, Jeffrey E. Larson Dec 1996

Adaptive Neural Network Controller For Atm Traffic, Jeffrey E. Larson

Theses and Dissertations

Broadband-Integrated Services Digital Networks (B-ISDN), along with Asynchronous Transfer Mode (ATM), were designed to meet the requirements of modern communication networks to handle multiple users and a wide variety of diverse traffic including voice, data and video. ATM responds to requests for admission to the network by analyzing whether or not the grade of service (GOS) requirement, specified in the admission request, can be guaranteed without violating the GOS guaranteed to traffic already accepted into the network. The GOS is typically a parameter such as cell loss rate (CLR), average delay, or some other measurement associated with network performance. In …

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Performance Analysis Of Dynamic Routing Protocols In A Low Earth Orbit Satellite Data Network, Richard F. Janoso Dec 1996

Performance Analysis Of Dynamic Routing Protocols In A Low Earth Orbit Satellite Data Network, Richard F. Janoso

Theses and Dissertations

Modern warfare is placing an increasing reliance on global communications. Currently under development are several Low Earth Orbit (LEO) satellite systems that propose to deliver voice and data traffic to subscribers anywhere on the globe. However, very little is known about the performance of conventional routing protocols under orbital conditions where the topology changes on a scale of minutes rather than days. This thesis compares two routing protocols in a LEO environment. One (Extended Bellman-Ford) is a conventional terrestrial routing protocol, while the other (Darting) is a new protocol which has been proposed as suitable for use in LEO networks. …

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