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Air Force Institute of Technology

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Articles 2311 - 2340 of 2678

Full-Text Articles in Physical Sciences and Mathematics

A Study Of Cumulative Trauma Disorders Of The Upper Extremities And Occupation In Wright-Patterson Adir Force Base Civilian Personnel, Scott T. Hillstead Sep 1995

A Study Of Cumulative Trauma Disorders Of The Upper Extremities And Occupation In Wright-Patterson Adir Force Base Civilian Personnel, Scott T. Hillstead

Theses and Dissertations

This study utilized a case-control methodology to describe and analyze the 115 cases of occupational illnesses reported by civilian employees of Wright-Patterson Air Force Base (AFB) between 1990 and 1995. Determining if a statistically significant association existed between age and duration of employment risk factors and cumulative trauma disorders (CTDs) was a primary objective. The frequency of CTDs among the various organizations at Wright-Patterson AFB are also described. The research could not prove the existence of a significant association for the 44 subjects and 176 controls matched on occupational group. However, the demographic and other descriptive results may form a …

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Calibration Of The System Evaluation And Estimation Of Resources Software Estimation Model (Seer-Sem) For The Air Force Space And Missile Systems Center (Smc), Kolin D. Rathmann Sep 1995

Calibration Of The System Evaluation And Estimation Of Resources Software Estimation Model (Seer-Sem) For The Air Force Space And Missile Systems Center (Smc), Kolin D. Rathmann

Theses and Dissertations

This study examined whether calibration of the SEER-SEM impacted the effort estimates generated by the model for software developments- A historical database was provided by the Space and Missile System's Center Los Angeles, and used as the model's input data. The data was stratified into four usable platforms, military ground command and-control, military ground signal processing, military specification avionics, and military mobile. Each platform's data sets were split, the majority of points for calibration of the model, and the rest for model validation. The accuracy of SEER to this particular data set is limited, yet the model did respond to …

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Ohmic Contact To Ion Implanted Gallium Arsenide Antimonide For Application To Indium Aluminum Arsenide-Gallium Arsenide Antimonide Heterostructure Insulated-Gate Field Effect Transistors, Kenneth G. Merkel Ii Jul 1995

Ohmic Contact To Ion Implanted Gallium Arsenide Antimonide For Application To Indium Aluminum Arsenide-Gallium Arsenide Antimonide Heterostructure Insulated-Gate Field Effect Transistors, Kenneth G. Merkel Ii

Theses and Dissertations

The p-channel In0.52Al0.48As-GaAs1-xSbx heterostructure insulated-gate field effect transistor (p-HIGFET) is a candidate for complementary integrated circuits due to superior cutoff characteristics and low gate leakage current. Advancement of the In0.52Al0.48As-GaAs1-xSbx p-HIGFET requires improved source-drain design. Five main tasks were accomplished to achieve this goal. First, thermal limits of the In0.52Al0.48As-GaAs0.51Sb0.49 HIGFET were investigated. Second, the temperature dependence of band gap and impurity energies were determined for beryllium doped In0.52Al0.48. Third, high acceptor concentrations were obtained …

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Optimal Wavefront Reconstruction For A Coherent Diffracted Field, William W. Arrasmith Jun 1995

Optimal Wavefront Reconstruction For A Coherent Diffracted Field, William W. Arrasmith

Theses and Dissertations

In sheared coherent beam interferometric imaging, an estimate of the average reflectivity profile of the object can be computed from measurements of point to point phase differences in the far field interference pattern and a suitable phase reconstruction technique. The phase difference information is encoded in the irradiance of three identical, shifted and superimposed speckled laser beam patterns. A minimum variance phase reconstruction technique is presented to estimate the phase of the field in the measurement plane from the phase differences and evaluate its performance. Prior knowledge of the phase covariance is used in the minimum variance reconstructor. Analytic calculations …

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Biomedical Data Interpolation For 3-D Visualization, Ming-Chung Chen Jun 1995

Biomedical Data Interpolation For 3-D Visualization, Ming-Chung Chen

Theses and Dissertations

Medical imaging devices that produce three-dimensional data usually produce the data in the form of image slices. In such images, the resolution in z direction is lower than in x and y directions. Before extracting and displaying objects in such images, an interpolated 3-D gray-scale volume image can be generated via image interpolation techniques to fill in the missing information. The subject of this thesis is the applying three different interpolation techniques to generate intermediate slices and comparing their qualities. The three interpolation techniques are linear interpolation, cubic spline interpolation, and Fourier interpolation. We also apply the CT image matching …

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The Mathematics Of Measuring Capabilities Of Artificial Neural Networks, Martha A. Carter Jun 1995

The Mathematics Of Measuring Capabilities Of Artificial Neural Networks, Martha A. Carter

Theses and Dissertations

Researchers rely on the mathematics of Vapnik and Chervonenkis to capture quantitatively the capabilities of specific artificial neural network (ANN) architectures. The quantifier is known as the V-C dimension, and is defined on functions or sets. Its value is the largest cardinality 1 of a set of vectors in Rd such that there is at least one set of vectors of cardinality 1 such that all dichotomies of that set into two sets can be implemented by the function or set. Stated another way, the V-C dimension of a set of functions is the largest cardinality of a set, such …

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Optimal Mixed-Norm Control Synthesis For Discrete-Time Linear Systems, David R. Jacques Jun 1995

Optimal Mixed-Norm Control Synthesis For Discrete-Time Linear Systems, David R. Jacques

Theses and Dissertations

A mixed-norm approach to control synthesis for discrete time linear systems is developed. Specifically, the problem of minimizing the H2 norm of a transfer function, subject to a combination of ℓ1 and-or H∞ norm constraints on dissimilar but related transfer functions is considered. The uniqueness of the optimal solution is shown, and numerical methods for approximating the optimal solution to within arbitrary accuracy are developed. These methods generally result in high order compensators which can not be implemented in most practical applications. In response to this, a numerical method is developed which solves for suboptimal solutions of …

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Physiologically-Based Pharmacokinetic Modeling Of Skin Absorption Using Dermal Subcompartments, Richard L. Bookout Jr. Jun 1995

Physiologically-Based Pharmacokinetic Modeling Of Skin Absorption Using Dermal Subcompartments, Richard L. Bookout Jr.

Theses and Dissertations

Dermal penetration of chemicals and drugs is important to both toxicologists and pharmacologists. Drug developers try to enhance and environmental professionals try to limit penetration of chemicals through the skin. Both can use predictive biologically-based mathematical models to assist in understanding the processes involved. When these models are based on physiological and biochemical parameters which can be measured in the laboratory, they can be extremely useful. Appropriately validated models based on first principles can be predictive of human exposures when the processes involved are adequately understood. In this thesis we develop four new physiologically-based pharmacokinetic (PBPK) models to predict blood …

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A Robust Method Of Solving Nonlinear Boundary Value Problems Via Modified Compromise Programming, John L. Zornick May 1995

A Robust Method Of Solving Nonlinear Boundary Value Problems Via Modified Compromise Programming, John L. Zornick

Theses and Dissertations

This study is an extension of Ng's previous work in which goal programming was used to determine an approximate solution to a boundary value problem. This approach follows the same basic approach developed by Ng in which the method of collocation was recast as a compromise programming model. Hence, instead of solving a system of simultaneous nonlinear equations, one seeks a compromise solution which minimizes (in a weighted residual sense) a vector norm of the differential equation residuals. A difference in this approach is that it makes use of a genetic algorithm as the optimizing engine as opposed to the …

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Estimation Of The Captive-Carry Survival Function For The Advanced Medium Range Air-To-Air Missile (Amraam), David R. Denhard Mar 1995

Estimation Of The Captive-Carry Survival Function For The Advanced Medium Range Air-To-Air Missile (Amraam), David R. Denhard

Theses and Dissertations

This thesis considers the problem of estimating the survival function of an item (probability that the item functions for a time greater than a given time t) from sampling data subject to partial right censoring (a portion of the items in the sampling data have not yet been observed to fail). Specifically the thesis describes several parametric and non-parametric statistical models that can be used when the sampling data is subject to partial right censoring. These models are applied to the case of estimating the captive-carry survival function of the AIM-120A Advanced Medium Range Air-to-Air Missile (AMRAAM).

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Nonlinear Time Series Analysis, James A. Stewart Mar 1995

Nonlinear Time Series Analysis, James A. Stewart

Theses and Dissertations

This thesis applies neural network feature selection techniques to multivariate time series data to improve prediction of a target time series. Two approaches to feature selection are used. First, a subset enumeration method is used to determine which financial indicators are most useful for aiding in prediction of the S&P 500 futures daily price. The candidate indicators evaluated include RSI, Stochastics and several moving averages. Results indicate that the Stochastics and RSI indicators result in better prediction results than the moving averages. The second approach to feature selection is calculation of individual saliency metrics. A new decision boundary-based individual saliency …

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A Decision Model For Environmental Assessment Of Process Waste Products, Kyle F. Byard Mar 1995

A Decision Model For Environmental Assessment Of Process Waste Products, Kyle F. Byard

Theses and Dissertations

Environmental managers must compare the potential impacts of waste products when deciding upon courses of action. The estimation and comparison of these impacts is a subjective process, and few methods of comprehensive, quantitative comparison of waste products currently exist. The intent of this study is to develop a decision methodology to evaluate the environmental impacts of waste products and to score them for comparison. The method will follow established system design principles and incorporate significant characteristics of the waste material. Scores derived to represent the environmental impacts of materials will then he analyzed employing statistical and probabilistic methods to assess …

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Multipoint Quadratic Approximation For Numerical Optimization, Michael A. Blaylock Mar 1995

Multipoint Quadratic Approximation For Numerical Optimization, Michael A. Blaylock

Theses and Dissertations

A quadratic approximation for nonlinear functions is developed in order to realize computational savings in solving numerical optimization problems. Function and gradient information accumulated from multiple design points during the iteration history is used in estimating the Hessian matrix. The approximate Hessian matrix is the available for a second order Taylor series approximation to the functions of interest. Several truss and frame models will be used to demonstrate the effectiveness of the new Multipoint Quadratic Approximation (MQA) in solving structural optimization problems.

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Groundwater Model Parameter Estimation Using Response Surface Methodology, Richard M. Cotman Mar 1995

Groundwater Model Parameter Estimation Using Response Surface Methodology, Richard M. Cotman

Theses and Dissertations

This thesis examined the use of response surface methodology (RSM) to estimate the parameters of a finite-element groundwater model. An existing two-dimensional, steady-state flow model of a fractured carbonate groundwater system in southwestern Ohio served as the calibration target data set. A Plackett-Burman screening design showed that only four of the ten hydraulic conductivity zones significantly contributed to the output of the finite-element model. Also, the effective porosity parameter did not significantly affect the model's output. Using only the four significant hydraulic conductivity parameters; four two-level, four-factor designed experiments were conducted to exploit the first-order response surface defined by a …

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A New Goodness-Of-Fit Test For The Gamma Distribution Based On Sample Spacings From Complete And Censored Samples, Huseyin Duman Mar 1995

A New Goodness-Of-Fit Test For The Gamma Distribution Based On Sample Spacings From Complete And Censored Samples, Huseyin Duman

Theses and Dissertations

This thesis studies a new goodness-of-fit test for the gamma distribution with known shape parameter. This test statistic, Z*, is based on spacings from complete or censored samples. The size of samples varied between 5 and 35. The critical value tables were generated for the Z* test statistic for complete and censored samples. The critical values were obtained for five different significance levels: 0.20 0.15, 0.10, 0.05, and 0.01. An extensive power study, containing 50,000 Monte Carlo runs was conducted using nine alternative distributions, Ha. It was observed that the Z* test statistic was more powerful against certain …

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Analysis Of Heads-Up Display Quickening Versus Handling Qualities, Gary M. Konnert Mar 1995

Analysis Of Heads-Up Display Quickening Versus Handling Qualities, Gary M. Konnert

Theses and Dissertations

This study investigated an analytical means of selecting the quickening time constant for the standardized Heads-Up Display flight path marker. The theoretically determined time constant allowed a faster, less resource intensive means of selecting the quickening time constant. The theoretically best time constant for pilot-aircraft handling qualities was equal to the airframe pitch attitude high frequency zero time constant, Tθ2. Flight test indicated an empirical, more labor intensive method yielded better handling qualities, even though paper analysis indicated the theoretical method was better. The theoretically determined time constant gave slightly lower handling qualities. but was less costly to …

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Acquiring Consistent Knowledge For Bayesian Forests, Darwyn O. Banks Mar 1995

Acquiring Consistent Knowledge For Bayesian Forests, Darwyn O. Banks

Theses and Dissertations

This thesis develops a methodology and a tool for knowledge acquisition with the new probabilistic knowledge representation-the Bayesian Forest. It establishes the structure of the Knowledge Acquisition and Maintenance module of the Probabilities. Expert Systems, Knowledge and Inference (PESKI) architecture. The tool, MACK, is designed to be used directly by the domain expert(s) rather than by knowledge engineer(s), and thus supports automated knowledge acquisition. This research determines and implements the constraints necessary to ensure the consistency of Bayesian Forest knowledge bases as data is both acquired and subsequently maintained. The impact to the PESKI architecture of time-dependent information and default …

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An Improved Solution Methodology For The Arsenal Exchange Model (Aem), Jeffery D. Weir Mar 1995

An Improved Solution Methodology For The Arsenal Exchange Model (Aem), Jeffery D. Weir

Theses and Dissertations

The purpose of this research was to design a solution methodology for the Arsenal Exchange Model (AEM) that is faster and contains less precision error than the current one. The current solution methodology modifies some of the original constraints and uses a computationally slow matrix inverter. The improved methodology uses a revised simplex algorithm to first solve a subproblem having only the weapon constraints generated by the AEM. Given this optimal allocation, hedge constraints and target constraints that are violated by the current solution are added to the original subproblem. A dual simplex algorithm is used to find the optimal …

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Formal Foundations For The Specification Of Software Architecture, Mark J. Gerken Mar 1995

Formal Foundations For The Specification Of Software Architecture, Mark J. Gerken

Theses and Dissertations

This investigation establishes a formal foundation for software architecture that allows for the specification of large, non-trivial software systems using well founded, consistency preserving construction techniques. Two fundamental problems were addressed: how to define and express architectures formally using the concept of theories, and how architecture theories can be practically applied in specification construction. The initial stages of this investigation sought to establish a formal, mathematical relationship between functional specifications of behavior and specifications defining system structure. Experimental results lead to the conclusion that architectures defining the structure of functional operations can be defined using functional logic, but more complex …

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Teaching Accommodation Task Skills: From Human Demonstration To Robot Control Via Artificial Neural Networks, Paul V. Whalen Mar 1995

Teaching Accommodation Task Skills: From Human Demonstration To Robot Control Via Artificial Neural Networks, Paul V. Whalen

Theses and Dissertations

A simple edge-mating task, performed automatically by accommodation control, was used to study the feasibility of using data collected during a human demonstration to train an artificial neural network (ANN) to control a common robot manipulator to complete similar tasks. The 2-dimensional (planar) edge-mating task which aligns a peg normal to a fiat table served as the basis for the investigation. A simple multi-layered perceptron (MLP) ANN with a single hidden layer and linear output nodes was trained using the back-propagation algorithm with momentum. The inputs to the ANN were the planar components of the contact force between the peg …

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Response Surface Methodology As A Sensitivity Tool In Decision Analysis, David A. Meyers Mar 1995

Response Surface Methodology As A Sensitivity Tool In Decision Analysis, David A. Meyers

Theses and Dissertations

The purpose of this study is to evaluate response surface methodology as a sensitivity analysis tool in the area of decision analysis. The advent of low-cost personal computer software, such as DPLTM, has created an accessible tool with the ability to frame and solve influence diagrams for decision problems. This study provides a comparison of current sensitivity analysis techniques vs those made possible through response surface methodology (RSM). Sensitivity analysis alternatives are demonstrated on a decision problem concerning the evaluation of force structure options for the Department of Defense. Sensitivity analysis is performed on both one-way and two-way perturbations of …

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The Effect Of Repeatedly Sampling An Embedded Metamodel On The Simulation Response, John Kent Patterson Mar 1995

The Effect Of Repeatedly Sampling An Embedded Metamodel On The Simulation Response, John Kent Patterson

Theses and Dissertations

This study investigated the effect on simulation output of repeatedly sampling an embedded metamodel. A metamodel is said to be embedded within a simulation if it is used to replace a submodule of that simulation. Replacing a deterministic module with an embedded deterministic metamodel poses no apparent mathematical problems. However, using a deterministic metamodel to replace a stochastic simulation component could require additional corrective actions. This research was performed in two phases. The first phase dealt with a set of tandem queues. It was shown that as each queue was sequentially replaced with a metamodel, the total system variance was …

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Spatial Time-Series: Pollution Pattern Recognition Under Irregular Interventions, Samuel A. Wright Mar 1995

Spatial Time-Series: Pollution Pattern Recognition Under Irregular Interventions, Samuel A. Wright

Theses and Dissertations

The Fernald Environmental Restoration Management Corporation (FERMCO) has noted the introduction of arsenic contamination to groundwater around the area of the groundwater recovery system, which captures uranium contaminated groundwater. The introduction of arsenic occurs during high levels of pumping and is particularly sensitive to the western two of the five pumps. Auto-Regressive Moving Average (ARMA) and Spatial-Temporal ARMA (STARMA) empirical analyses are used to model the level of arsenic contamination found through time. The intervention of varied levels of pumping is modeled with a transfer function using analytic techniques to create a causal intervention transfer function input series to give …

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Analysis And Extension Of Model-Based Software Executives, Keith E. Lewis Jan 1995

Analysis And Extension Of Model-Based Software Executives, Keith E. Lewis

Theses and Dissertations

This research developed a comprehensive description of the simulation environment of Architect, a domain-oriented application composition system being developed at the Air Force Institute of Technology to explore new software engineering technologies. The description combines information from several previous research efforts and Architect's source code into a single, comprehensive document. A critical evaluation of the simulation environment was also performed, identifying improvements and modifications that enhance Architecture's application execution capabilities by reducing complexity and execution time. The analysis was then taken one step further and presented extensions to the current simulation environment. The extensions included investigating the feasibility of mixed-mode …

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Visage: Improving The Ballistic Vulnerability Modeling And Analysis Process, Brett F. Grimes Jan 1995

Visage: Improving The Ballistic Vulnerability Modeling And Analysis Process, Brett F. Grimes

Theses and Dissertations

The purpose of this thesis was to improve the process of modeling and analyzing ballistic vulnerability data. This was accomplished by addressing two of the more urgent needs of vulnerability analysts; the ability to display fault tree data and to edit target descriptions. A vulnerability data visualization program called VISAGE was modified to meet these needs. VISAGE was originally created to preview static shotline plots and subsequently grew into a full-featured visualization package for vulnerability target descriptions and analyses data. The next logical step in the programs evolution was to include the needed editing and fault tree display capabilities. The …

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Multicriteria Mission Route Planning Using A Parallel A* Search, Michael S. Gudaitis Dec 1994

Multicriteria Mission Route Planning Using A Parallel A* Search, Michael S. Gudaitis

Theses and Dissertations

The Mission Route Planning (MRP) Problem falls into the general class of multicriteria path search problems. Multiple criteria are evaluated to select an optimal aircraft mission route through a hostile environment. Criteria for distance travelled and radar exposure are combined into a single cost function for route evaluation. Radar calculations are performed dynamically. The A* search algorithm is applied to the MRP problem, and a parallel implementation is developed and tested. A unique combination of distributed OPEN lists with a global CLOSED list strategy produced fast execution times on the Paragon. Test cases for scenarios with 15 radars took less …

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Generalized Probabilistic Reasoning And Empirical Studies On Computational Efficiency And Scalability, Eric P. Baenen Dec 1994

Generalized Probabilistic Reasoning And Empirical Studies On Computational Efficiency And Scalability, Eric P. Baenen

Theses and Dissertations

Expert Systems are tools that can be very useful for diagnostic purposes, however current methods of storing and reasoning with knowledge have significant limitations. One set of limitations involves how to store and manipulate uncertain knowledge: much of the knowledge we are dealing with has some degree of uncertainty. These limitations include lack of complete information, not being able to model cyclic information and limitations on the size and complexity of the problems to be solved. If expert systems are ever going to be able to tackle significant real world problems then these deficiencies must be corrected. This paper describes …

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Unification Of Larch And Z-Based Object Models To Support Algebraically-Based Design Refinement: The Larch Perspective, Catherine J. Lin Dec 1994

Unification Of Larch And Z-Based Object Models To Support Algebraically-Based Design Refinement: The Larch Perspective, Catherine J. Lin

Theses and Dissertations

This research describes the feasibility of developing object-oriented LARCH specifications, part of a dual approach for formally extending object-oriented analysis models using LARCH and Z. The first phase consisted of two steps establishing a set of transformation heuristics for algebraically representing object models and implementing a robust LARCH parser. The LARCH parser produced abstract syntax trees ASTs of objects forming the basis for analyzing the similarities and differences between Z-based and LARCH-based object representations. The second phase used the analysis of LARCH and Z to identify fundamental core constructs in the languages and abstract syntax trees. These core constructs consisted …

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Modeiing Operational Task Assignment In Air Force Wing Command And Control, Robert J. Hunt Dec 1994

Modeiing Operational Task Assignment In Air Force Wing Command And Control, Robert J. Hunt

Theses and Dissertations

This research investigated the feasibility of applying software engineering technology to the Air Force wing command and control (C2) domain. As part of this research, domain analysis and object-oriented techniques were investigated and a specific approach was chosen to analyze the domain. Analysis of the domain resulted in an object-oriented domain model that captured the key objects, operations, and associations, and behavior of wing C2. The domain model was used to design and implement a prototype software tool that enables wing decision makers to assign resources to mission tasks and to make assessments about automation's impact on wing C2 operations.

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Improving Intrusion Detection In Unix-Based Networks, David R. Landry Dec 1994

Improving Intrusion Detection In Unix-Based Networks, David R. Landry

Theses and Dissertations

Computer security has not kept pace with the rapid growth of networked systems. Through its connection to the Internet, the Department of Defense is vulnerable to computer-based attacks. Current intrusion detection systems are still unproven, too complicated, or too costly for most system security officers to implement. The attack methods used by system intruders are known and can be represented as groups of commands called attack signatures. This thesis investigates methods for detecting intruders by monitoring command usage. Testing was conducted in both controlled and uncontrolled circumstances. With controlled testing, it was shown that 7 of the 11 signatures could …

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