Physical Sciences and Mathematics Commons^™

Term Reduction Using Directed Congruence Closure, L Paul Chew

Computer Science Technical Reports

Many problems in computer science can be described in terms of reduction rules that tell how to transform terms. Problems that can be handled in this way include interpreting programs, implementing abstract data types, and proving certain kinds of theorems. A terms is said to have a normal form if it can be transformed, using the reduction rules, into a term to which no further reduction rules apply. In this paper, we extend the Congruence Closure Algorithm, an algorithm for finding the consequences of a finite set of equations, to develop Directed Congruence Closure, a technique for finding the normal …

Planar Graphs And Sparse Graphs From Efficient Motion Planning In The Plane, L Paul Chew

Computer Science Technical Reports

Given a source, a destination, and a number of obstacles in the plane, the Motion Planning Program is to determine the best path to move an object (a robot) from the source to the destination without colliding with any of the obstacles. For us, motion is restricted to the plane, the robot is represented by a point, and the obstacles are represented by a set of polygons with a total of n vertices among all the polygonal obstacles.

Applying The Take-Grant Protection Model, Matt Bishop

Computer Science Technical Reports

The Take-Grant Protection Model has in the past been used to model multilevel security hierarchies and simple protection systems. The models are extended to include theft of rights and sharing of information, and additional security policies are examined. The analysis suggests that in some cases the basic rules of the Take-Grant Protection Model should be augmented to represent the policy properly; when appropriate, such modifications are made and their effects with respect to the policy and its Take-Grant representations are discussed.

A Proactive Password Checker, Matt Bishop

Computer Science Technical Reports

Password selection has long been a difficult issue; traditionally, passwords are either assigned by the computer or chosen by the user. When the computer does the assignments, the passwords are often hard to remember; when the User makes the selection, the passwords are often easy to guess. This paper describes a technique, and a mechanism, to allow users to select passwords which to them are easy to remember but to others would be very difficult to guess. The technique is site, user, and group configurable, and allows rapid changing of constraints impossed upon the passwords. Although experience with this technique …

Administrator's Guide To The Digital Signature Facility "Rover", Matt Bishop

Computer Science Technical Reports

This document describes the installation and maintenance of the rover utility, which provides a digital signature capability for internet messages.

Finding Optimal Quorum Assigments For Distributed Databases, Donald B. Johnson, Larry Raab

Computer Science Technical Reports

Replication has been studied as a method of increasing the availability of a data item in a distributed database subject to component failures and consequent partitioning. The potential for partitioning requires that a protocol be employed which guarantees that any access to a data item is aware of the most recent update to that data item. By minimizing the number of access requests denied due to this constraint, we maximize availability. In the event that all access requests are reads, placing one copy of the data item at each site clearly leads to maximum availability. The other extreme, all access …

Effects Of Replication On Data Availability, Donald B. Johnson, Larry Raab

Computer Science Technical Reports

In this paper we examine the effects of replication on the availability of data in a large network. This analysis differs from previous analyses in that it compares the performance of a dynamic consistency control protocol not only to that of other consistency control protocols, but also to the performance of non-replication and to an upper bound on data availability. This analysis also differes in that we gather extensive simulations on large networks subject to partitions at realistically high component reliabilities. We examine the dynamic consistency protocol presented by Jajodia and Mutchler [9, 12] and by Long and Paris[18] along …

A Simulation Testbed For Image Compression Algorithms, Andrew Francis Laine

All Computer Science and Engineering Research

This paper presents an overview of the design and development of a real-time (30 frames/sec) simulation testbed for evaluating and comparing image compression algorithms. The system was motivated by the need to visualize the performance of a novel compression algorithm when operating on moving pictures originating from "live" video sources. The simulation utilities are designed to exploit the parallelism of a Pixar Image Computer and high-throughput of a parallel disk assembly. The design of two key utilities are discussed: (1) A program to format precomputed four channel (RGBA) 256 X 256 color frames onto a parallel disk assembly. (2) A …

Faster Circuits And Shorter Formulas For Multiple Addition, Multiplication And Symmetric Boolean Functions, Michael Paterson, Uri Zwick, Nicholas Pippenger

All HMC Faculty Publications and Research

A general theory is developed for constructing the shallowest possible circuits and the shortest possible formulas for the carry-save addition of n numbers using any given basic addition unit. More precisely, it is shown that if BA is a basic addition unit with occurrence matrix N, then the shortest multiple carry-save addition formulas that could be obtained by composing BA units are of size n1p+o(1)/, where p is the unique real number for which the Lp norm of the matrix N equals 1. An analogous result connects the delay matrix M of the basic addition unit BA and the minimal …

Using Metrics To Quantify Development, Harlan D. Mills, P. B. Dyson

The Harlan D. Mills Collection

No abstract provided.

Highland: A Graph-Based Parallel Processing Environment For Heterogeneous Local Area Networks, Ralph W. Wilkerson, Douglas E. Meyer

Computer Science Faculty Research & Creative Works

No abstract provided.

Role Of Term Symmetry In E-Completion Procedures, Ralph W. Wilkerson, Blayne E. Mayfield

Computer Science Faculty Research & Creative Works

No abstract provided.

Dawgs - A Distributed Compute Server Utilizing Idle Workstations, Henry Clark, Bruce M. Mcmillin

Computer Science Faculty Research & Creative Works

A collection of powerful workstations interconnected by a local area network can be utilized as compute servers when left idle by their owners. DAWGS allows users to submit jobs for execution on an idle workstation somewhere on a local area network. DAWGS uses a distributed scheduler and a bidding scheme to determine on which machine to run a process. DAWGS can properly redirect all the I/O of a remotely executing process and can checkpoint and then subsequently restart the process, even if the restart is on a different machine than the checkpoint. Our method is different from other work in …

Computational Intelligence In Cad/Cam Applications, Chaman Sabharwal, Thomas G. Melson, Martin D. Fraser

Computer Science Faculty Research & Creative Works

This paper presents a fundamental, direct, and powerful approach to the surface/surface intersection problem in CAD/CAM applications. The algorithm is designed and implemented in three steps: a) Preprocessing- locate the potentially intersecting sections of the surfaces and decompose the surfaces into surface elements within specified flatness tolerance; b) Intersection- decompose the possibly intersecting pairs of surface elements into continuous surface triangulations to find the approximate intersections between the pairs of surface elements; c) Postprocessing-assemble the intersection primitives into curves of intersection, refine the accuracy of computed intersection points, and compact the intersection curves. This surface/surface intersection algorithm is applicable to …

Distributed Evaluation Of An Iterative Function For All Object Pairs On A Simd Hypercube, Fikret Erçal

Computer Science Faculty Research & Creative Works

An efficient distributed algorithm for evaluating an iterative function on all pairwise combinations of C objects on an SIMD hypercube is presented. The algorithm achieves uniform load distribution and minimal, completely local interprocessor communication.

An Expert System To Convert Knowledge-Based Geological Engineering Systems Into Fortran, Ralph W. Wilkerson, Jill J. Cress

Computer Science Faculty Research & Creative Works

A knowledge-based geographic information system (KBGIS) for geological engineering map (GEM) production was developed in GoldWorks, an expert system development shell. Using this shell, the geological engineer is able to develop a rule base for a particular application that results in a valid GEM. However, this implementation failed as a practical production system due to the excessive execution time required to produce a GEM. To solve this problem, a conversion expert system was developed which accepted, as input, a KBGIS and produced, as output, the equivalent Fortran code. Two major objectives are accomplished as a result of this system: GEN …

An Experimental Study On Reject Ratio Prediction For Vlsl Circuits: Kokomo Revisited, Dharam Vir Das, Sharad C. Seth, Paul T. Wagner, John Anderson, Vishwani Agrawal

School of Computing: Faculty Publications

Assuring product quality is becoming increasingly more important for the semiconductor chip manufacturers. The reject ratio (defect level) provides a simple and accurate measure of a product's quality. However, measuring the reject ratio of tested chips is often not feasible or accurate. Statistical techniques for reject ratio prediction provide a possible way out of this dilemma. In this paper, we report on an experiment to verify the accuracy of reject ratio predictions by the available approaches. The data collection effort includes instrumenting the wafer probe test to obtain chip failures as a function of applied vectors and running a fault …

Data Acquisition And Control Program For Chromatographic And Spectroscopic Studies, M. Keith Hudson, William G. Hood, Robert Henson

Journal of the Arkansas Academy of Science

An IBMPC compatible computer was interfaced to an Ithaco 3962 lock-in-amplifier. The computer controlled the functions of the lock-in-amplifier, acquired and stored data, and allowed for real time or off-line processing of data. Computer/amplifier connection was made via RS-232-C serial interface. Programmed in Microsoft Quick BASIC, the computer assumed the role of a dedicated chromatographic integrator. This reduced the overall instrumentation expense by eliminating a dedicated chromatographic integrator. The computer program supplied much greater flexibility in control and data interpretation. To show its utility, the program was applied to a study of the infrared emission from a flame upon the …

Impact Of Microprocessor Protected Mode Programming On Undergraduate Education N Engineering Technology, Robert L. Douglas

Journal of the Arkansas Academy of Science

No abstract provided.

A Statistical Theory Of Digital Circuit Testability, Sharad C. Seth, Vishwani D. Agrawal, Hassan Farhat

School of Computing: Faculty Publications

When test vectors are applied to a circuit, the fault coverage increases. The rate of increase, however, could be circuit dependent. A relation between the average fault coverage and circuit testability is developed in this paper. The statistical formulation allows computation of coverage for deterministic and random vectors. We discuss the following applications of this analysis: determination of circuit testability from fault simulation, coverage prediction from testability analysis, prediction of test length, and test generation by fault sampling.

High-Level Microprogramming: An Optimising C Compiler For A Processing Element Of A Cad Accelerator, Paul Kenyon, Prathima Agrawal, Sharad C. Seth

School of Computing: Faculty Publications

The development of a high-level language compiler for a micro-programmable processing element (PE) in the MARS multicomputer is described. MARS, an MIMD message passing machine, was designed to speed up VLSI CAD and similar other non-numerical applications. The need for sup port of a high-level language at the PE level of a multicomputer is considered, and the choice of C as an appropriate programming language is justified. Special features found in VLSI processors are examined along with compiler support for them.

Conventional re-targetable compiler techniques are shown to be inadequate for the highly concurrent micro-programmable PE. These techniques must be …

An Underwater Science And Resource Database Management System And Proposed Applications To Marine Geographic Information Systems, Ivar Babb

Marine Affairs Theses and Major Papers

The National Undersea Research Program (NURP) is a federally-funded program that provides scientists with modern in situ technology that allows them to conduct research that goes beyond the constraints of traditional oceanographic methodology. NURP is comprised of five regional centers that administer underwater science, and through the principal investigators that are supported generate a vast quantity of diverse data. This data and information bank consists of the following: raw environmental data, logistical data, locational data, information about the scientists, video and still photograph documentation, and publication information. This paper describes the theory behind the implementation of a Database Management System …

The Use Of Remote Sensing Techniques And Geographic Information Systems By Coastal Managers In Rhode Island, Margaret H. Sano

Marine Affairs Theses and Major Papers

Planners and managers must understand the physical and anthropogenic changes taking place within the coastal zone to provide effective management. Remote sensing techniques and Geographic Information Systems (GIS) are excellent tools for contributing data and analytical capabilities to identify possible conflicts within the coastal zone. This study examines the potential and actual use of these technologies by coastal managers within Rhode Island. Potential usage is discussed in terms of the range of data available and the feasibility of using the data for coastal problems. Also, GIS capabilities in Rhode Island are explored. Finally a survey designed to measure the actual …

Experimental Comparison Of Bidding And Drafting Load Sharing Protocols, Andrew Ross, Bruce M. Mcmillin

Computer Science Faculty Research & Creative Works

In recent years, a dramatic rise in the number of personal workstations interconnected via local area networks has occurred in the workplace. These can be organized as distributed computing systems. The combined computing power of these systems are often greater than mainframes of a decade ago, and usually less expensive. There is a growing interest in harnessing this often-underutilized power. Researchers are focusing their attention on remote execution of processes as one solution. An additional topic of research is to balance a workload among a series of computers. Remote execution is made possible because the distributed operating system provides migration …

Human-Machine Interface For Tactical Air Traffic Control Communications, Alan Mastin

UNF Graduate Theses and Dissertations

This thesis proposes the design for a prototype device that would be used by Air Traffic Controllers in the radar environment to input tactical Air Traffic Control (ATC) instructions to be sent to aircraft via the Mode S digital data link network. The purpose of the device is to reduce the time required to issue instructions and to eliminate misunderstandings that occur when instructions are issued over voice transmission frequencies. The purpose of this thesis was to develop the device in the most ergonomically suited manner based on the air traffic controller's communications requirements. Digital communications systems include both airborne …

Adaptive Histogram Equalization, A Parallel Implementation, Charles W. Kurak Jr.

UNF Graduate Theses and Dissertations

Adaptive Histogram Equalization (AHE) has been recognized as a valid method of contrast enhancement. The main advantage of AHE is that it can provide better contrast in local areas than that achievable utilizing traditional histogram equalization methods. Whereas traditional methods consider the entire image, AHE utilizes a local contextual region.

However, AHE is computationally expensive, and therefore time-consuming. In this work two areas of computer science, image processing and parallel processing, are combined to produce an efficient algorithm. In particular, the AHE algorithm is implemented with a Multiple-Instruction-Multiple-Data (MIMD) parallel architecture. It is proposed that, as MIMD machines become more …

Linda Implementations Using Monitors And Message Passing, Alan L. Leveton

UNF Graduate Theses and Dissertations

Linda is a new parallel programming language that is built around an interprocess communication model called generative communication that differs from previous models in specifying that shared data be added in tuple form to an environment called tuple space, where a tuple exists independently until some process chooses to use it. Interesting properties arise from the model, including space and time uncoupling as well as structured naming. We delineate the essential Linda operations, then discuss the properties of generative communication. We are particularly concerned with implementing Linda on top of two traditional parallel programming paradigms - process communication through globally …

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, January 1990, College Of Engineering And Computer Science, Wright State University

BITs and PCs Newsletter

A fourteen page newsletter created by the Wright State University College of Engineering and Computer Science that addresses the current affairs of the college.

Pipelining Data Compression Algorithms, R. L. Bailey, R. Mukkamala

Computer Science Faculty Publications

Many different data compression techniques currently exist. Each has its own advantages and disadvantages. Combining (pipelining) multiple data compression techniques could achieve better compression rates than is possible with either technique individually. This paper proposes a pipelining technique and investigates the characteristics of two example pipelining algorithms. Their performance is compared with other well-known compression techniques.

Educational Software Development Using Hypertext And Expert System Software Concepts, Siripong Malasri, Roger R. Easson

Journal of the Arkansas Academy of Science

This paper presents two computer software concepts: hypertext and expert systems; which are useful for educational software development. Good educational software enhances the learning process and offers opportunities for faculty to provide additional materials for independent studies, which would otherwise be impossible, due to the limited time and incredible growing rate of technological progress. The hypertext concept offers the students a non-linear learning style, while the expert system concept provides explanation facilities for students to probe the logic of the systems. Both approaches are extremely useful for educational software. With the proper tools, the courseware can be implemented easily and …