Open Access. Powered by Scholars. Published by Universities.®

Digital Commons Network™

Open Access. Powered by Scholars. Published by Universities.®

Computer Sciences

Institution
Keyword
Publication Year
Publication
Publication Type
File Type

Articles 61561 - 61590 of 63753

Full-Text Articles in Entire DC Network

Enhanced Animation Of Parallel Algorithms, Michael D. Lack Dec 1991

Enhanced Animation Of Parallel Algorithms, Michael D. Lack

Theses and Dissertations

Algorithm animation is a visualization method used to enhance understanding of the functioning of an algorithm or program. Visualization is used for many purposes, including education, algorithm research, performance analysis, and program debugging. This research, which follows from previous work, examines algorithm animation requirements for the various visualization purposes and extends the capabilities of an existing facilities, the AFIT algorithm Animation Research Facility (AAARF). The structure of AAARF is summarised and its visualization capabilities presented, analysed and compared with other similar packages. This research focuses on the parallel data requirements of the AAARF users, and the meaningful display of large …

Go to article

Graph-Based Visualization Of Formal Specification And Domain Specific Languages, Randel K. Langloss Dec 1991

Graph-Based Visualization Of Formal Specification And Domain Specific Languages, Randel K. Langloss

Theses and Dissertations

This research develops and implements Visual Refine, a graph-based visualization system, for the Refine wide-spectrum formal specification language and environment developed and marketed by Reasoning Systems, Inc. Refine specifications are represented in the Refine object base as abstract syntax trees (AST). Using these AST representations, one-to-one mappings are defined between nodes of the AST and the graphical icons of Visual Refine. Visual Refine uses these mappings to implement a set of formal transformations. Each transformation is encapsulated within a Refine rule, and this set of rules form the Visual Refine transformation system. The Visual Refine transformation system, in conjunction with …

Go to article

Establishing A Methodology For Evaluation And Selecting Computer Aided Software Engineering Tools For A Defined Software Engineering Environment At The Air Force Institute Of Technology School Of Engineering, Jody L. Mattingly Dec 1991

Establishing A Methodology For Evaluation And Selecting Computer Aided Software Engineering Tools For A Defined Software Engineering Environment At The Air Force Institute Of Technology School Of Engineering, Jody L. Mattingly

Theses and Dissertations

This thesis identifies the software engineering environment (SEE) as it exists at the Air Force Institute of Technology (AFIT) School of Engineering. It also describes the software process model employed and the software development methods presented as part of the curriculum. Based on this information, criteria was established to evaluate computer aided software engineering (CASE) tools being considered for integration into the SEE. Each criterion was weighted to indicate its importance when selecting CASE tools. The criteria were further used to establish a methodology to be used to evaluate and select the CASE tools under consideration as well as future …

Go to article

Improved Task Scheduling For Parallel Simulations, Andrew E. Mcnear Dec 1991

Improved Task Scheduling For Parallel Simulations, Andrew E. Mcnear

Theses and Dissertations

The objective of this investigation is to design, analyze, and validate the generation of optimal schedules for simulation systems. Improved performance in simulation execution times can greatly improve the return rate of information provided by such simulations resulting in reduced development costs of future computer/electronic systems. Optimal schedule generation of precedence-constrained task systems including iterative feedback systems such as VHDL or war gaming simulations for execution on a parallel computer is known to be N P-hard. Efficiently parallelizing such problems takes full advantage of present computer technology to achieve a significant reduction in the search times required. Unfortunately, the extreme …

Go to article

A Spatially Partitioned Parallel Simulation Of Colliding Objects, Robert S. Moser Dec 1991

A Spatially Partitioned Parallel Simulation Of Colliding Objects, Robert S. Moser

Theses and Dissertations

This study investigated the application of a conservative synchronization paradigm to the classical, distributed pool balls simulation executed on an eight node, Intel iPSC/2 hypercube. Wieland's concept of spatial partitioning and limited data replication was used. Analysis has shown that 100% parallelization of execution is possible in a conservative environment via assignment of multiple sectors to nodes. Two conservative formulations for minimum safe time were derived. A tradeoff exists between scalability and efficiency. Optimum sectoring prediction has been shown possible through application of linear regression techniques. The results of this research reveal that a conservative approach to distributed, discrete event …

Go to article

Three-Dimensional Medical Image Registration Using A Patient Space Correlation Technique, Patrick J. Rizzuto Jr. Dec 1991

Three-Dimensional Medical Image Registration Using A Patient Space Correlation Technique, Patrick J. Rizzuto Jr.

Theses and Dissertations

The routine clinical use of three-dimensional data provided by modern medical imaging procedures is often impeded by the difficulty in accurately correlating the resultant volume datasets. These data are frequently obtained at different times using the same modality, or images of the same patient are sometimes produced using more than one imaging modality. In order to analyze the similarities and differences between such images, it is necessary for the medical imaging data to be spatially aligned using a process known as image registration. This research investigated a structure-based image registration technique based upon simple, three-dimensional relationships among user identified landmarks. …

Go to article

Design Of Style-V — A Translator To Convert Standard Vhdl Into A Stylized Form For Automated Microcode Generation, Dennis A. Rumbley Dec 1991

Design Of Style-V — A Translator To Convert Standard Vhdl Into A Stylized Form For Automated Microcode Generation, Dennis A. Rumbley

Theses and Dissertations

This thesis provides an analysis and preliminary design of Style V, a source-to-source computer language translator. Style-V converts IEEE standard VHDL into a special style of VHDL defined for a commercial tool, the Integrated Design Automation System (IDAS). Thirteen mappings between standard VHDL and the IDAS subset were identified. The mappings were analyzed using Domain Analysis and Modern Structured Analysis techniques. Four processes covering several of the mappings were completely analyzed. One mapping to convert CASE statements to IF statements was implemented. Since the IDAS restricts designs to bit logic, a method for representing multilevel logic with bit logic was …

Go to article

Effect Of Spatial Locality Prefetching On Structural Locality, Dirk D. Schalch Dec 1991

Effect Of Spatial Locality Prefetching On Structural Locality, Dirk D. Schalch

Theses and Dissertations

The purpose of this research was to analyze the effect that spatial locality prefetching in cache memory has on the structural locality of program memory referencing behavior. To examine this, a software simulator was built to model a proposed two-level cache memory subsystem. The proposed subsystem was designed to use spatial locality prefetching to exploit the structural locality contained in executing computer workloads. New memory referencing models were developed to incorporate the combined use of structural locality and spatial locality prefetching. From these models, equations were derived to predict the hit rates for both caches. Combined with the state transition …

Go to article

An Application Of The Object-Oriented Paradigm To A Flight Simulator, Dennis J. Simpson Dec 1991

An Application Of The Object-Oriented Paradigm To A Flight Simulator, Dennis J. Simpson

Theses and Dissertations

This thesis describes the object-oriented software development techniques that were used to analyze, design and implement a flight simulator. The objective of this thesis was to present a comprehensive object-oriented software development methodology and show how it was used in constructing an actual application. An extensive review of current object-oriented practices is presented along with the methods that were used to take the flight simulator from analysis to design and through to implementation. The description of the methodology concentrates upon the design and implementation phases of the object-oriented software lifecycle. Examples from the design of the flight simulator demonstrate how …

Go to article

A Hybrid Approach To Battlefield Parallel Discrete Event Simulation, Steven R. Soderholm Dec 1991

A Hybrid Approach To Battlefield Parallel Discrete Event Simulation, Steven R. Soderholm

Theses and Dissertations

This thesis describes a method of parallelizing a battlefield discrete event simulation. The method combines elements of conservative time synchronization together with elements of optimistic computation and local rollback on a message passing hardware architecture. The battle simulation features aircraft moving in a battle area and launching missiles at enemy aircraft. Aircraft are randomly grouped into logical process (LPs), and a single LP is assigned to each processor. Aircraft state information is replicated across all LPs. Only the LP with the minimum next event time can execute safely. While one LP is executing safely all other LPs are precomputing their …

Go to article

Parallelizing Serial Code For A Distributed Processing Environment With An Application To High Frequency Electromagnetic Scattering, Paul R. Work Dec 1991

Parallelizing Serial Code For A Distributed Processing Environment With An Application To High Frequency Electromagnetic Scattering, Paul R. Work

Theses and Dissertations

This thesis investigates the parallelization of existing serial programs in computational electromagnetics for use in a parallel environment. Existing Algorithms for calculating the radar cross section of a object are covered, and a ray-tracing code is chosen for implementation on a parallel machine. Current parallel architectures are introduced and a suitable parallel machine is selected for the implementation of the chosen ray tracing algorithm. The standard techniques for the parallelization of serial code are discussed, including load balancing and decomposition considerations, and appropriate methods for the parallelization effort are selected. A load balancing algorithm is modified to increase the efficiency …

Go to article

Formalization And Validation Of An Sadt Specification Through Executable Simulation In Vhdl, Daniel L. Eickmeier Dec 1991

Formalization And Validation Of An Sadt Specification Through Executable Simulation In Vhdl, Daniel L. Eickmeier

Theses and Dissertations

Formalizing an informal requirements specification, such as SADT, and executing the formal specification in a simulation environment, such as VHDL, provides a requirements analyst a means to validate the behavior of a specification early in the development life cycle. This research effort investigated and demonstrated the feasibility and benefit of transforming an SADT specification of a system into an equivalent VHDL executable simulation. Both non-time related behavior and concurrent, real-time related behavior is addressed. First, a decision table extension to SADT is created so that detailed, executable behavior can be specified. Next a mapping from SADT to VHDL is defined. …

Go to article

Robotic Tactile Sensors Fabricated From A Monolithic Silicon Integrated Circuit And A Piezoelectric Polyvinylidene Fluoride Thin Film, Craig S. Dyson Dec 1991

Robotic Tactile Sensors Fabricated From A Monolithic Silicon Integrated Circuit And A Piezoelectric Polyvinylidene Fluoride Thin Film, Craig S. Dyson

Theses and Dissertations

The purpose of this research effort was to design, fabricate, and test a tactile sensor system consisting of an external high impedance switch circuit, an external multiplexing circuit, and a tactile sensor IC. In order to accomplish this objective, a hardware design and selection process was implemented along with a logical test methodology. An external multiplexer circuit samples all of the array elements in 50 ms. The current prototype sensor has linearity spanning loads of 0.8 g to 135 g, a load resolution of 20 g, and a maximum bandwidth of 25 Hz. Using an elementary shape recognition algorithm the …

Go to article

Control Of A Large Flexible Space Structure Using Multiple Model Adaptive Algorithms, John A. Gustafson Dec 1991

Control Of A Large Flexible Space Structure Using Multiple Model Adaptive Algorithms, John A. Gustafson

Theses and Dissertations

The development and performance of moving-bank multiple model adaptive estimation (MMAE) and control (MMAC) algorithms for quelling vibrations induced in the SPICE 2 space structure are analyzed in this thesis. The structure consists of a large platform and a smaller platform connected by three legs in a tripod fashion. The model supplied by Phillips Laboratory, Kirtland AFB is used to develop a truth model and multiple reduced ordered filter models. The filter models are developed from modal analysis and internally balanced techniques. Deviations of the line-of-sight vector from the center of the large platform to the center of the smaller …

Go to article

Real Imagery As A Three Dimensional Display, Juan C. Echeverry Dec 1991

Real Imagery As A Three Dimensional Display, Juan C. Echeverry

Theses and Dissertations

This research effort implemented two 3-D display designs to assess their performance and effect on an observer's depth perception. Both 3-D displays produced real images for the observer to view. The first display setup combined a lens relay with a two concave mirror projector. The second display setup combined the two concave mirror projector with a diffuser. The lens relay/ two concave mirror projector combination was successful in imaging a source from the CRT to a point in space above the two mirror system. The problem was that the observer could not assess the image location by just looking at …

Go to article

An Investigation Of The Application Of Artificial Neural Networks To Adaptive Optics Imaging Systems, Andrew H. Suzuki Dec 1991

An Investigation Of The Application Of Artificial Neural Networks To Adaptive Optics Imaging Systems, Andrew H. Suzuki

Theses and Dissertations

Recurrent and feedforward artificial neural networks are developed as wavefront reconstructors. The recurrent neural network studied is the Hopfield neural network and the feedforward neural network studied is the single layer perceptron artificial neural network. The recurrent artificial neural network input features are the wavefront sensor slope outputs and neighboring actuator feedback commands. The feedforward artificial neural network input features are just the wavefront sensor slope outputs. Both artificial neural networks use their inputs to calculate deformable mirror actuator commands. The effects of training are examined.

Go to article

Caching And Writeback Policies In Parallel File Systems, David Kotz, Carla Schlatter Ellis Dec 1991

Caching And Writeback Policies In Parallel File Systems, David Kotz, Carla Schlatter Ellis

Dartmouth Scholarship

Improvements in the processing speed of multiprocessors are outpacing improvements in the speed of disk hardware. Parallel disk I/O subsystems have been proposed as one way to close the gap between processor and disk speeds. Such parallel disk systems require parallel file system software to avoid performance-limiting bottlenecks. We discuss cache management techniques that can be used in a parallel file system implementation. We examine several writeback policies, and give results of experiments that test their performance.

Go to article

A Case Study In Software Reuse: The Rntds Architecture, Barry J. Stevens Dec 1991

A Case Study In Software Reuse: The Rntds Architecture, Barry J. Stevens

Computer Science Theses & Dissertations

It has been asserted that the most significant gains in software productivity will come from increased levels of software reuse. Some economic models for predicting savings through software reuse exist, but none are based on actual project experience. This paper surveys those models and presents the results of a case study, the Restructured Naval Tactical Data Systems (RNTDS) architecture, in the light of those models. According to the models, software reuse via the RNTDS architecture has enabled the production of fourteen major computer programs at five to twenty-one percent of the cost to create them without software reuse. Organizational characteristics …

Go to article

Practical Prefetching Techniques For Parallel File Systems, David Kotz, Carla Schlatter Ellis Dec 1991

Practical Prefetching Techniques For Parallel File Systems, David Kotz, Carla Schlatter Ellis

Dartmouth Scholarship

Parallel disk subsystems have been proposed as one way to close the gap between processor and disk speeds. In a previous paper we showed that prefetching and caching have the potential to deliver the performance benefits of parallel file systems to parallel applications. In this paper we describe experiments with practical prefetching policies, and show that prefetching can be implemented efficiently even for the more complex parallel file access patterns. We test these policies across a range of architectural parameters.

Go to article

Knowledge-Based Systems Approach For Offshore Safety Training, B. S. Lee, Venky Shankararaman Dec 1991

Knowledge-Based Systems Approach For Offshore Safety Training, B. S. Lee, Venky Shankararaman

Research Collection School Of Computing and Information Systems

A number of training methods has been used within the offshore industry to impart safety knowledge and safe operating skills. In this paper a Knowledge-Based Safety Training architecture is proposed. The architecture uses both expert system and hypertext methods and is also applicable to plants other than offshore platforms. Special attention is given to the types of knowledge dealt with in safety training and how to represent this knowledge and teach it using various teaching strategies.

Go to article

Documentation Requirements For Software Maintenance, Timothy S. Mcarthur Dec 1991

Documentation Requirements For Software Maintenance, Timothy S. Mcarthur

Theses and Dissertations

This study investigated the requirement for documentation during the maintenance phase of the software life cycle. Without proper documentation, maintenance personnel are not able to effectively understand the design of a software system and spend many hours performing design recovery before any type of maintenance can be performed. A review of existing information showed a wide range of opinion among the experts in the field of software maintenance and was not conclusive. A survey of Air Force software maintenance personnel was then conducted to determine the need, availability, and tailoring results of the documents listed on DOD-STD 2167A. The analysis …

Go to article

Reducing Requirements Errors Through The Use Of Computer-Aided Software Engineering (Case) Tools And During Requirements Analysis, Marvin B. Key Jr. Dec 1991

Reducing Requirements Errors Through The Use Of Computer-Aided Software Engineering (Case) Tools And During Requirements Analysis, Marvin B. Key Jr.

Theses and Dissertations

This study investigated whether using CASE tools in the requirements analysis phase of software development reduced the software coding errors attributable to requirement analysis. A survey of the population gathered data as to the current practices and efforts in the use of CASE tools. The data was gathered in two groups: a control group and a sample group. The data was analyzed by group and in various combinations to obtain a greater understanding into population trends and tendencies. The results of the research indicate that the Air Force does not use CASE tools to any great extent. Also, error and …

Go to article

Design And Application Of An Object Oriented Graphical Database Management System For Synthetic Environments, John A. Brunderman Dec 1991

Design And Application Of An Object Oriented Graphical Database Management System For Synthetic Environments, John A. Brunderman

Theses and Dissertations

The Air Force Institute of Technology (AFIT) is investigating the use of synthetic environments for military applications under the sponsorship of Rome Laboratories (RL). Areas under investigation include mission planning, battle management and flight simulation. The work reported in this thesis focuses on the object-oriented design and implementation of the Graphical Database Management System (GDMS) used to support research in these areas. GDMS provides the data structures, file format and algorithms to manage and render hierarchical, three-dimensional, polygonal models. Flexibility and adaptability were key factors in its design. A secondary objective of this research was to demonstrate the functionality of …

Go to article

Logic Programming In Digital Circuit Design, Joseph W. Eicher Dec 1991

Logic Programming In Digital Circuit Design, Joseph W. Eicher

Theses and Dissertations

The design of large, complex digital circuitry requires highly skilled engineers. Much of the time spent by these engineers in the design phase involves tasks that are repetitive, tedious, and slow. If these repetitive tasks are automated, the engineer can spend more time managing the design process and produce a better-quality design in less time. Logic programming can be used to automate design tasks, even those that require a high degree of skill. This thesis investigates several aspects of the digital circuit design process that involve pattern-matching paradigms suitable for encoding in the logic programming language Prolog.

Go to article

A Cache Design To Exploit Structural Locality, Curtis M. Winstead Dec 1991

A Cache Design To Exploit Structural Locality, Curtis M. Winstead

Theses and Dissertations

A design and VHDL implementation of a content-addressable memory (CAM) to exploit structural locality is the subject of this research. The concept of structural locality is that memory locations are referenced in the same order as they were previously referenced. Therefore, if memory locations that exhibit structural locality can be made available to the CPU (Center Processing Unit) through a fast data store, an increase in speed of the computer system can be realized. The CAM's purpose is to store memory references in the order they were used by the CPU and prefetch these locations to a smaller on- chip …

Go to article

An Animated Graphical Postprocessor For The Saber Wargame, Gary W. Klabunde Dec 1991

An Animated Graphical Postprocessor For The Saber Wargame, Gary W. Klabunde

Theses and Dissertations

One of the most cost effective ways to learn and home the skills necessary to conduct and win a war is through the use of realistic computer simulations of conflict, or wargames. The Saber wargame was developed for just this purpose. Saber is a multisided, theater-level simulation developed by the Air Force Institute of Technology for the Air Force Wargaming Center. It models conventional, nuclear, and chemical warfare between aggregated air and ground forces. To aid in the realism, the effects of logistics, satellites, weather, and intelligence are represented. Saber provides an avenue for senior level joint service officers to …

Go to article

Face Recognition With The Karhunen-Loeve Transform, Pedro F. Suarez Dec 1991

Face Recognition With The Karhunen-Loeve Transform, Pedro F. Suarez

Theses and Dissertations

The major goal of this research was to investigate machine recognition of faces. The approach taken to achieve this goal was to investigate the use of Karhunen-Loe've Transform (KLT) by implementing flexible and practical code. The KLT utilizes the eigenvectors of the covariance matrix as a basis set. Faces were projected onto the eigenvectors, called eigenfaces, and the resulting projection coefficients were used as features. Face recognition accuracies for the KLT coefficients were superior to Fourier based techniques. Additionally, this thesis demonstrated the image compression and reconstruction capabilities of the KLT. This theses also developed the use of the KLT …

Go to article

Optimal Parallel Algorithms For Periods, Palindromes And Squares (Preliminary Version), Alberto Apostolico, Dany Breslauer, Zvi Galil Nov 1991

Optimal Parallel Algorithms For Periods, Palindromes And Squares (Preliminary Version), Alberto Apostolico, Dany Breslauer, Zvi Galil

Department of Computer Science Technical Reports

No abstract provided.

Go to article

Gcache: A Generalized Caching Mechanism, Douglas E. Comer, Shawn Ostermann Nov 1991

Gcache: A Generalized Caching Mechanism, Douglas E. Comer, Shawn Ostermann

Department of Computer Science Technical Reports

No abstract provided.

Go to article

Representation Requirements For Supporting Knowledge-Based Construction Of Decision-Models In Medicine, Tze-Yun Leong Nov 1991

Representation Requirements For Supporting Knowledge-Based Construction Of Decision-Models In Medicine, Tze-Yun Leong

Research Collection School Of Computing and Information Systems

This paper analyzes the medical knowledge required for formulating decision models in the domain of pulmonary infectious diseases (PIDs) with acquired immunodeficiency syndrome (AIDS). Aiming to support dynamic decision-modeling, the knowledge characterization focuses on the ontology of the clinical decision problem. Relevant inference patterns and knowledge types are identified.

Go to article

First Prev Next Last