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Theses and Dissertations

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Articles 2431 - 2460 of 2733

Full-Text Articles in Computer Sciences

Implementation Of An Ada95 Crosscompiler For The Real-Time Executive For Military Systems (Rtems), Kendall M. Lemley Jr. Dec 1996

Implementation Of An Ada95 Crosscompiler For The Real-Time Executive For Military Systems (Rtems), Kendall M. Lemley Jr.

Theses and Dissertations

This thesis represents a continuation of the assessment of the Unified Telerobotics Architecture Project (UTAP), a proposed Air Force standard. This architecture was developed by the NASA Jet Propulsion Laboratory and the National Institute of Standards under contract to the Air Force Materiel Command Robotics and Automation Center of Excellence at Kelly AFB, Texas. Due to operating system constraints, the only UTAP implementation to date has required a separate software interface layer, adding complexity and overhead to the overall system, while reducing portability. This thesis proposes a long term effort to design and implement UTAP-compliant application software devoid of this …

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Simworx: An Ada Distributed Simulation Application Framework Supporting Hla And Dis, Earl C. Pilloud Dec 1996

Simworx: An Ada Distributed Simulation Application Framework Supporting Hla And Dis, Earl C. Pilloud

Theses and Dissertations

This research consisted of the analysis, design, and implementation of a reusable application framework for distributed simulation which is compliant with both the DoD High Level Architecture (HLA) for Modeling and Simulation and the Distributed Interactive Simulation (DIS) standards. The goal was to create an Ada-based system for experimentation in distributed simulation. A subsidiary goal was to integrate the system with an existing Air Force Institute of Technology (AFIT) application framework for virtual simulations, Easy_Sim. The application framework was designed using object oriented techniques to enable experimenters to customize it via inheritance extension. The application framework, named SimWorx, consists of …

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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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Speaker Recognition By Hidden Markov Models And Neural Networks, Erik J. Zeek Dec 1996

Speaker Recognition By Hidden Markov Models And Neural Networks, Erik J. Zeek

Theses and Dissertations

As humans, we develop the ability to identify people by their voice at an early age. Getting computers to perform the same task has proven to be an interesting problem. Speaker recognition involves two applications, speaker identification and speaker verification. Both applications are examined in this effort. Two methods are employed to perform speaker recognition. The first is an enhancement of hidden Markov models. Rather than alter some part of the model itself, a single-layer perceptron is added to perform neural post-processing. The second solution is the novel application of an enhanced Feature Space Trajectory Neural Network to speaker recognition. …

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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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The Development Of A Scenario Translator For Distributed Simulations, Heon-Gyu Park Dec 1996

The Development Of A Scenario Translator For Distributed Simulations, Heon-Gyu Park

Theses and Dissertations

There exists a variety of simulation generation and analysis products which have differing purposes and functions designed to simulate a real military battlefield. Due to the particular purpose of each simulation it is impractical to use one scenario of a simulation directly with another simulation without a translator since there is no standard scenario format. In the current environment interoperability between simulations is becoming more important in large scale simulations and distributed exercises. The Scenario File Translator (SFT) provides an easy and accurate way to create a scenario from a heterogeneous simulation. The SFT can load and save the three …

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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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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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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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Artificial Cochlea Design Using Micro-Electro-Mechanical Systems, George C. Dalton Ii Dec 1996

Artificial Cochlea Design Using Micro-Electro-Mechanical Systems, George C. Dalton Ii

Theses and Dissertations

The use of Micro-Electro-Mechanical Systems (MEMS) in the design of an artificial cochlea is investigated in depth. Interdigitated finger (comb), cantilever, bridge, and mirror resonators are presented as possible devices used to implement the artificial cochlea. These resonators are demonstrated to be extremely high Q devices, capable of being tuned with a simple DC bias. This suggests a possible change to existing cochlea models that claim highly complex AC feedback as being responsible for changes in the damping of the basilar membrane. The new cochlea model presented here, using MEMS to approximate the tuning of the basilar membrane, may be …

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Solar System Modeler: A Distributed, Virtual Environment For Space Visualization And Gps Navigation, Gary E. Williams Dec 1996

Solar System Modeler: A Distributed, Virtual Environment For Space Visualization And Gps Navigation, Gary E. Williams

Theses and Dissertations

The Solar System Modeler (SM) extends the Space Modeler developed in 1994. It provides a virtual environment enabling an explorer to dynamically investigate near Earth satellites, deep space probes, planets, moons, and other celestial phenomena. The explorer navigates the virtual environment via mouse selected options from menu panels while wearing a tracked, head mounted display (HMD). Alternatively, a monitor may replace the HMD and keyboard controls replace head tracking. The SM's functionality is extended by the ability to broadcast simulated GPS satellite transmissions in compliance with Distributed Interactive Simulation (DIS) protocol standards. The transmissions include information found in true GPS …

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Molecular Articulation In Response To Interactive Atomic Forces In Docker, Todd R. Kellett Dec 1996

Molecular Articulation In Response To Interactive Atomic Forces In Docker, Todd R. Kellett

Theses and Dissertations

Molecular docking aids in the design of materials supporting the current and future needs of the warfighter by simulating the real-world results of combining molecules. Specifically, it supports research and development in novel non-linear optical materials for laser-hardening and other advanced optical applications. Potential uses for these materials range from personnel and optical system laser protection to holographic information displays. DOCKER, our baseline docking system, minimizes the computational overhead of the simulation by modeling the molecules as rigid objects. This simplification can cause DOCKER's solutions to disagree with the real-world results, because molecules flex as they react to one another …

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Survivability Analysis Of The Iridium Low Earth Orbit Satellite Network, Douglas K. Stenger Dec 1996

Survivability Analysis Of The Iridium Low Earth Orbit Satellite Network, Douglas K. Stenger

Theses and Dissertations

This thesis evaluates the survivability of the proposed Iridium Low Earth Orbit (LEO) Satellite Network. In addition to the complete Iridium constellation, three degraded Iridium constellations are analyzed. This analysis occurs via the use of simulation models, which are developed to use three dynamic routing algorithms over three loading levels. The Iridium network models use a common set of operating assumptions and system environments. The constellation survivability was determined by comparing packet rejection rates, hop' counts, and average end to end delay performance between the various network scenarios. It was concluded that, based on the established scenarios, the proposed Iridium …

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Elicitation Of Formal Software Specifications From An Object-Oriented Domain Model, Timothy Karagias Dec 1996

Elicitation Of Formal Software Specifications From An Object-Oriented Domain Model, Timothy Karagias

Theses and Dissertations

The ability to provide automated support for the generation of formal software specifications would lead to decreased software development time. By eliciting the needed information from a software developer and harvesting the proper parts of a domain model, a software specifications document could be created. This research establishes the feasibility of producing customized software specifications based on an object-oriented domain model. The research was conducted in three phases. The first phase was to define the requirements for the Elicitor Harvester. Those requirements were balanced between the capabilities of the existing Knowledge Based Software Engineering (KBSE) software used at AFIT and …

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A Specific Network Link And Path Likelihood Prediction Tool, Gary K. Moy Dec 1996

A Specific Network Link And Path Likelihood Prediction Tool, Gary K. Moy

Theses and Dissertations

Communications have always been a crucial part of any military operation. As the pace of warfare and the technological complexity of weaponry have increased, so has the need for rapid information to assess battlefield conditions. Message passing across a network of communication nodes allowed commanders to communicate with their forces. It is clear that an accurate prediction of communication usage through a network will provide commanders with useful intelligence of friendly and unfriendly activities. Providing a specific network link and path likelihood prediction tool gives strategic military commanders additional intelligence information and enables them to manage their limited resources more …

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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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Practical Implementation Of Multiple Model Adaptive Estimation Using Neyman-Pearson Based Hypothesis Testing And Spectral Estimation Tools, Peter D. Hanlon Sep 1996

Practical Implementation Of Multiple Model Adaptive Estimation Using Neyman-Pearson Based Hypothesis Testing And Spectral Estimation Tools, Peter D. Hanlon

Theses and Dissertations

This study investigates and develops various modifications to the Multiple Model Adaptive Estimation (MMAE) algorithm. The standard MMAE uses a bank of Kalman filters, each based on a different model of the system. Each of the filters predict the system response, based on its system model, to a given input and form the residual difference between the prediction and sensor measurements of the system response. Model differences in the input matrix, output matrix, and state transition matrix, which respectively correspond to an actuator failure, sensor failure, and an incorrectly modeled flight condition for a flight control failure application, were investigated …

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The Design Of A Financial Management Database System, Edward G. Leszynski Sep 1996

The Design Of A Financial Management Database System, Edward G. Leszynski

Theses and Dissertations

This research led to the design and development of a financial management database system for the Aeronautical Systems Center (AS C) Environmental Management (EM) Systems Program Office (SPO), which has the responsibility of managing the environmental contracts for the Government-Owned, Contractor-Operated (GOCO) plants that are owned by the Air Force. This thesis investigated the various 'development strategies' and 'methodologies' described in the Management Information Systems literature in order to devise an end-user development strategy capable of meeting the EM SPO's requirements. In addition, the information requirements, conceptual design and prototyping, and procedures phases of the System Development Life Cycle (SDLC) …

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Background Graphics: A Decision-Making Hindrance Or Enhancement?, David L. Peeler Jr. Sep 1996

Background Graphics: A Decision-Making Hindrance Or Enhancement?, David L. Peeler Jr.

Theses and Dissertations

This thesis investigated the influence, if any, of background graphics on the decision making process. Specifically the hypotheses tested the affect of background graphics on a decision makers accuracy and confidence. A literature review revealed an abundance of graphic research but little reference to the use of background graphics. Using guidelines previously created for high integrity graphics, a timed 2 x 2 factorial experimental design was developed to compare the responses to both traditional graphics and those treated with background graphics. One hundred forty-seven subjects, all employees of the United States Air Force or defense contractors were involved in the …

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Development Of A Standard Set Of Indicators And Metrics For Artificial Intelligence (Ai) And Expert System (Es) Software Development Efforts, Derek F. Cossey Sep 1996

Development Of A Standard Set Of Indicators And Metrics For Artificial Intelligence (Ai) And Expert System (Es) Software Development Efforts, Derek F. Cossey

Theses and Dissertations

The purpose of this research was to identify a standard set of indicators and metrics that can be used by program managers to improve their abilities to direct development efforts involving Artificial Intelligence (AI) and Expert Systems (ES). This research addresses two objectives. The first objective is to identify an appropriate set of software indicators and metrics to be used by government program offices for the management of development efforts involving software systems for AI and ES. The second objective is to demonstrate how the resources of the National Software Data and Information Repository (NSDIR) can be used in order …

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Calibration Of The Softcost-R Software Cost Model To The Space And Missile Systems Center (Smc) Software Database (Swdb), Steven V. Southwell Sep 1996

Calibration Of The Softcost-R Software Cost Model To The Space And Missile Systems Center (Smc) Software Database (Swdb), Steven V. Southwell

Theses and Dissertations

The rising number and importance of Department of Defense software developments, when combined with declining defense budgets, has resulted in a critical need to accurately plan and manage software development costs and schedules. Unfortunately, the increasing size, complexity, and diversity of these software developments has made accurate estimating problematic. Uncalibrated software cost models have not generally produced reliable results due to generic default parameters and improper usage. The default parameters cannot hope to accurately represent and predict the wide variability of software efforts to which the models are being applied. However, some of the models have achieved improved accuracy by …

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Calibration Of The Checkpoint Model To The Space And Missile Systems Center (Smc) Software Database (Swdb), Karen R. Mertes Sep 1996

Calibration Of The Checkpoint Model To The Space And Missile Systems Center (Smc) Software Database (Swdb), Karen R. Mertes

Theses and Dissertations

This study analyzed the effect of calibration on the performance of the CHECKPOINT Version 2.3.1 software cost estimating model. Data used for input into the model were drawn from the FY 95 USAF SMC Software Database (SWDB) Version 2.1. A comparison was made between the model's accuracy before and after calibration. This was done using records which were not used in calibration, referred to as validation points. A comparison of calibration points, both before and after, was done in order to assess whether calibration results in more consistency within the data set used. Six measures such as magnitude of relative …

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Formal Transformations From Graphically-Based Object-Oriented Representations To Theory-Based Specifications, Scott A. Deloach Jun 1996

Formal Transformations From Graphically-Based Object-Oriented Representations To Theory-Based Specifications, Scott A. Deloach

Theses and Dissertations

Formal software specification has long been touted as a way to increase the quality and reliability of software; however, it remains an intricate, manually intensive activity. An alternative to using formal specifications is to use graphically-based, semi-formal specifications such as those used in many object-oriented specification methodologies. While semi-formal specifications are generally easier to develop and understand, they lack the rigor and precision of formal specification techniques. The basic premise of this investigation is that formal software specifications can be constructed using correctness preserving transformations from graphically-based object-oriented representations. In this investigation, object-oriented specifications defined using Rumbaugh's Object Modeling Technique …

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A Methodology For Reengineering Relational Databases To An Object-Oriented Database, Pedro A. Linhares Lima Jun 1996

A Methodology For Reengineering Relational Databases To An Object-Oriented Database, Pedro A. Linhares Lima

Theses and Dissertations

This research proposes and evaluates a methodology for reengineering a relational database to an object-oriented database. We applied this methodology to reengineering the Air Force Institute of Technology Student Information System (AFITSIS) as our test case. With this test case, we could verify the applicability of the proposed methodology, especially because AFITSIS comes from an old version of Oracle RDBMS. We had the opportunity to implement part of the object model using an object-oriented database, and we present some peculiarities encountered during this implementation. The most important result of this research is that it demonstrated that the proposed methodology can …

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Performance Study Of A Brazilian Air Force Data Communications Network, Oswaldo Zanelli Jun 1996

Performance Study Of A Brazilian Air Force Data Communications Network, Oswaldo Zanelli

Theses and Dissertations

This thesis consists of a performance analysis of two network models using different protocols, the X.25 and Asynchronous Transfer Mode (ATM). X.25 is currently used in the data communications network infrastructure in the Brazilian Air Force. ATM is a high speed network technology. Simulations of both models were performed to compare the two technologies. This study examines the traffic load that each network can handle while still providing a good quality of service (QoS). The X.25 network model proved to have a sufficient capacity to handle the projected workload, but it presented a low QoS when a more intense traffic …

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Generalized Hidden Filter Markov Models Applied To Speaker Recognition, John M. Colombi Mar 1996

Generalized Hidden Filter Markov Models Applied To Speaker Recognition, John M. Colombi

Theses and Dissertations

Classification of time series has wide Air Force, DoD and commercial interest, from automatic target recognition systems on munitions to recognition of speakers in diverse environments. The ability to effectively model the temporal information contained in a sequence is of paramount importance. Toward this goal, this research develops theoretical extensions to a class of stochastic models and demonstrates their effectiveness on the problem of text-independent (language constrained) speaker recognition. Specifically within the hidden Markov model architecture, additional constraints are implemented which better incorporate observation correlations and context, where standard approaches fail. Two methods of modeling correlations are developed, and their …

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A Generic Intelligent Architecture For Computer-Aided Training Of Procedural Knowledge, Freeman A. Kilpatrick Jr. Mar 1996

A Generic Intelligent Architecture For Computer-Aided Training Of Procedural Knowledge, Freeman A. Kilpatrick Jr.

Theses and Dissertations

Intelligent Tutoring System (ITS) development is a knowledge-intensive task, suffering from the same knowledge acquisition bottleneck that plagues most Artificial Intelligence (AI) systems. This research presents an architecture that requires knowledge only in the form of a shallow knowledge base and a simulation to produce a training system. The knowledge base provides the basic procedural knowledge while the simulation provides context. The remainder of the knowledge required for training is learned through the interaction of these components in a state-space scenario exploration process and inductive machine learning. These knowledge components are used only at the interface level, allowing the internal …

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Application Of Autoregressive Moving Average Linear Prediction Filters To The Characterization Of Solar Wind-Magnetosphere Coupling, Carter N. Borst Jan 1996

Application Of Autoregressive Moving Average Linear Prediction Filters To The Characterization Of Solar Wind-Magnetosphere Coupling, Carter N. Borst

Theses and Dissertations

Linear prediction filtering techniques have been used in studying the coupling processes between the solar wind and magnetosphere. The magnetosphere is a complex, dynamic system with at least two independent coupling methods for energy input, driven and unloading. Linear models were built and tested on the Bargatze data set, consisting of over 70 days of geomagnetic indices and solar wind data ordered in 34 intervals of increasing geomagnetic activity. Linear filtering techniques employing single-and multiple-input, autoregressive models predicted values of the magnetic index AL from solar wind data. The impulse response curves of the AL-coupling function groups showed amplitude peaks …

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Objectism 3.0: A Software Architecture For The Development Of Portable Visual Simulation Applications, Shawn M. Hannan Dec 1995

Objectism 3.0: A Software Architecture For The Development Of Portable Visual Simulation Applications, Shawn M. Hannan

Theses and Dissertations

A visual simulation software architecture is a reusable design for visual simulation applications. This thesis effort was the third stage in an ongoing refinement of such an architecture, named ObjectSim. The primary goals of this stage were to improve the architecture by eliminating its dependence on two platform-specific graphics libraries (named GL and Performer, from Silicon Graphics, Inc.), and to examine the potential for expanding the architecture to accommodate distributed simulations. The effort resulted in a new version of the architecture which allows the development of visual simulation applications which take full advantage of the aforementioned libraries without calling those …

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Probabilistic Knowledge Base Validation, Howard T. Gleason Dec 1995

Probabilistic Knowledge Base Validation, Howard T. Gleason

Theses and Dissertations

Our work develops a new methodology and tool for the validation of probabilistic knowledge bases throughout their lifecycle. The methodology minimizes user interaction by automatically modifying incorrect knowledge; only the occurrence of incomplete knowledge involves interaction. These gains are realized by combining and modifying techniques borrowed from rule-based and artificial neural network validation strategies. The presented methodology is demonstrated through BVAL, which is designed for a new knowledge representation, the Bayesian Knowledge Base. This knowledge representation accommodates incomplete knowledge while remaining firmly grounded in probability theory.

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