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Articles 55801 - 55830 of 57999

Full-Text Articles in Physical Sciences and Mathematics

Porting Chorus To The Pa-Risc: Booting, Jon Inouye, Ravi Konuru, Jonathan Walpole, Marion Hakanson Jan 1992

Porting Chorus To The Pa-Risc: Booting, Jon Inouye, Ravi Konuru, Jonathan Walpole, Marion Hakanson

Computer Science Faculty Publications and Presentations

We started out with the low level Tut (HP-CX 2.0) boot code. One of our goals was to reuse as much of this code as possible, which would reduce the amount of low level code we would have to debug. This was very important, especially fiince the RP 9000/834 has a very complex I/O architecture and we lacked any sophisticated debugging tools. Writing the PA-Chorus boot code involved modifying the Tut code to match the Chorus startup sequence. In the remainder of this section, we present an overview of the PA-RISC boot mechanisms and the Chorus startup sequence. Sectlon 2 …


Porting Chorus To The Pa-Risc: Building, Debugging, Testing And Validation, Ravi Konuru, Marion Hakanson, Jon Inouye, Jonathan Walpole Jan 1992

Porting Chorus To The Pa-Risc: Building, Debugging, Testing And Validation, Ravi Konuru, Marion Hakanson, Jon Inouye, Jonathan Walpole

Computer Science Faculty Publications and Presentations

This document is part of a series of reports describing the design decisions made in porting the Chorus Operating System to the Hewlett-Packard 9000 Series 800 workstation. This document describes the environment for building the Chorus kernel, the various kernel tests, and the debugging environment used for porting the Chorus operating system to the HP PA-RISC.

The information contained in this paper will be of interest to people who wish to:

• Use the PA-Chorus kernel for development and/or modification, • Know about the build environment for Chorus kernel on PA-RISC, • Know about the PA-Chorus approach to debugging, • …


Porting Chorus To The Pa-Risc: Project Overview, Jonathan Walpole, Marion Hakanson, Jon Inouye, Ravi Konuru Jan 1992

Porting Chorus To The Pa-Risc: Project Overview, Jonathan Walpole, Marion Hakanson, Jon Inouye, Ravi Konuru

Computer Science Faculty Publications and Presentations

This document is part of a series of reports describing the design decisions made in porting the Chorus Operating System to the Hewlett-Packard 9000 Series 800 workstation. This document presents an overview of the project, and outlines the other reports in the series and the relationships between them.


Porting Chorus To The Pa-Risc: Virtual Memory Manager, Jon Inouye, Marion Hakanson, Ravi Konuru, Jonathan Walpole Jan 1992

Porting Chorus To The Pa-Risc: Virtual Memory Manager, Jon Inouye, Marion Hakanson, Ravi Konuru, Jonathan Walpole

Computer Science Faculty Publications and Presentations

This document describes the port ofthe Chorus virtual memory manager to the Hewlett-Packard Precision Architecture rusc (PA-RISC) workstation. The information contained in this paper will be of interest to people who:

• intend to port the Chorus virtual memory section. • intend to port a virtual memory design to the Hewlett-Packard PA-RISC.

The reader is strongly encouraged to read the following PA-Chorus documents before reading this document:

• Technical Report CSE-92-3, Porting Chorus to the PA-RISC: Project Overview


Measurement Of Τ Decays Involving Η Mesons, M. Artuso, M. Thulasidas Jan 1992

Measurement Of Τ Decays Involving Η Mesons, M. Artuso, M. Thulasidas

Research Collection School Of Computing and Information Systems

No abstract provided.


On Sources In Comparability Graphs, With Applications, Stephan Olariu Jan 1992

On Sources In Comparability Graphs, With Applications, Stephan Olariu

Computer Science Faculty Publications

We characterize sources in comparability graphs and show that our result provides a unifying look at two recent results about interval graphs.


Isospin Mass Splittings From Precision Measurements Of D*-D Mass Differences, D. Bortoletto, Manoj Thulasidas Jan 1992

Isospin Mass Splittings From Precision Measurements Of D*-D Mass Differences, D. Bortoletto, Manoj Thulasidas

Research Collection School Of Computing and Information Systems

Using the decay modes, D*+→D+π0 and D*0→D0π0, we have measured the D*+−D+ and D*0−D0 mass differences to be 140±0.08±0.06 and 142.12±0.05±0.05 MeV, respectively. Combining these measurements with the Particle Data Group average for the D*+−D0 mass difference, we obtain isospin mass splittings for D*+−Dusp*0 and D+−D0 of 3.32±0.08±0.05 and 4.80±0.10 ±0.06 MeV. We discuss the implications of these measurements for models of isospin mass differences and model-dependent estimates of fD.


The Morphology Of Convex Polygons, Stephan Olariu Jan 1992

The Morphology Of Convex Polygons, Stephan Olariu

Computer Science Faculty Publications

A simple polygon P is said to be unimodal if for every vertex of P, the Euclidian distance function to the other vertices of P is unimodal. The study of unimodal polygons has emerged as a fruitful area of computational and discrete geometry. We study unimodality properties of a number of special convex polygons from the morphological point of view. In particular, we establish a hierarchy among three classes of convex polygons in terms of their unimodality properties.


A Tree Representation For P4-Sparse Graphs, B. Jamison, Stephan Olariu Jan 1992

A Tree Representation For P4-Sparse Graphs, B. Jamison, Stephan Olariu

Computer Science Faculty Publications

A graph G is P4-sparse if no set of five vertices in G induces more than one chordless path of length three. P4-sparse graphs generalize both the class of cographs and the class of P4-reducible graphs. We give several characterizations for P4-sparse graphs and show that they can be constructed from single-vertex graphs by a finite sequence of operations. Our characterization implies that the P4-sparse graphs admit a tree representation unique up to isomorphism. Furthermore, this tree representation can be obtained in polynomial time.


Design And Analysis Techniques For Concurrent Blackboard Systems, John William Mcmanus Jan 1992

Design And Analysis Techniques For Concurrent Blackboard Systems, John William Mcmanus

Dissertations, Theses, and Masters Projects

Blackboard systems are a natural progression of Artificial Intelligence based systems into a more powerful problem solving technique. They provide a way for several highly specialized knowledge sources to cooperate to solve large, complex problems. Blackboard systems incorporate the concepts developed by rule-based and expert systems programmers and include the ability to add conventionally coded knowledge sources. The small and specialized knowledge sources are easier to develop and test, and are hosted on hardware specifically suited to the task that they are solving.;Designing and developing blackboard systems is a difficult process. The designer is attempting to balance several conflicting goals …


Verification Of Fault-Tolerant Clock Synchronization Systems, Paul S. Miner Jan 1992

Verification Of Fault-Tolerant Clock Synchronization Systems, Paul S. Miner

Dissertations, Theses, and Masters Projects

No abstract provided.


Code Generation Using A Backtracking Lr Parser, Laurie Anne Smith King Jan 1992

Code Generation Using A Backtracking Lr Parser, Laurie Anne Smith King

Dissertations, Theses, and Masters Projects

Although the parsing phase of the modern compiler has been automated in a machine independent fashion, the diversity of computer architectures inhibits automating the code generation phase. During code generation, some intermediate representation of a source program is transformed into actual machine instructions. The need for portable compilers has driven research towards the automatic generation of code generators.;This research investigates the use of a backtracking LR parser that treats code generation as a series of tree transformations.


High Performance Issues In Image Processing And Computer Vision, Jingyuan Zhang Jan 1992

High Performance Issues In Image Processing And Computer Vision, Jingyuan Zhang

Computer Science Theses & Dissertations

Typical image processing and computer vision tasks found in industrial, medical, and military applications require real-time solutions. These requirements have motivated the design of many parallel architectures and algorithms. Recently, a new architecture called the reconfigurable mesh has been proposed. This thesis addresses a number of problems in image processing and computer vision on reconfigurable meshes.

We first show that a number of low-level descriptors of a digitized image such as the perimeter, area, histogram and median row can be reduced to computing the sum of all the integers in a matrix, which in turn can be reduced to computing …


Program Maintenance And Code Reuse: Object Oriented Versus Procedure Oriented Programming, Beiramali Moradi Jan 1992

Program Maintenance And Code Reuse: Object Oriented Versus Procedure Oriented Programming, Beiramali Moradi

Theses

The purpose of this thesis is to address the problem of the increasing cost of program maintenance in the data processing world. On average, programmers today spend 60% of their time in program maintenance and that figure is increasing at an estimated rate of 1 % each year. The cost is staggering and almost every business would like to find ways of reducing maintenance costs. One way to help reduce maintenance and development costs is to improve code reusability. Both maintenance programming and code reusability are the focus of this thesis.

Today's most commonly used programming language style is procedure …


Bounds On Constraint Weight Parameters Of Hopfield Networks For Stability Of Optimization Problem Solutions, Gursel Serpen Jan 1992

Bounds On Constraint Weight Parameters Of Hopfield Networks For Stability Of Optimization Problem Solutions, Gursel Serpen

Electrical & Computer Engineering Theses & Dissertations

The purpose of the presented research is to study the convergence characteristics of Hopfield network dynamics. The relation between constraint weight parameter values and the stability of solutions of constraint satisfaction and optimization problems mapped to Hopfield networks is investigated. A theoretical development relating constraint weight parameter values to solution stability is presented. The dependency of solution stability on constraint weight parameter values is shown employing an abstract optimization problem. A theorem defining bounds on the constraint weight parameter magnitudes for solution stability of constraint satisfaction and optimization problems is proved. Simulation analysis on a set of optimization and constraint …


An Investigation Of Ibm Pc Computer Viruses Infection Rates And Types In A Western Australian Environment, Boon Guan Lee Jan 1992

An Investigation Of Ibm Pc Computer Viruses Infection Rates And Types In A Western Australian Environment, Boon Guan Lee

Theses : Honours

In recent years computer viruses have become increasingly significant as a form of computer abuse. By virtue of their reproductive capability, computer viruses can have cumulative and potentially catastrophic effects to the many people who use those affected computers. There is a growing concern in the computing community about these forms of electronic vandalism. This concern arises from the possible damage to stored information on which the work depends and the ensuing disruption of the work-place. Although the vandalism or purposeful abuse by introducing computer viruses to computer systems was originally mainly an American experience, research reports published by the …


Application Of Expert System Techniques For Award Implementation, Seng-Choon Yeoh Jan 1992

Application Of Expert System Techniques For Award Implementation, Seng-Choon Yeoh

Theses : Honours

This paper describes a pilot expert system project, PESWEA, developed in conjunction with The Western Australian Government Railways Commission (Westrail), to locate and implement an expert system pilot solution to the problems and complexities of the awards. The paper will outline the process used to develop and implement a solution to a business requirement. In particular, the methodologies for the project, shell selection, and knowledge acquisition will be presented and discussed. The fundamentals of expert systems will be discussed to provide the reader an insight into the technology. In addition, this paper reviews the literature relevant to the research questions. …


How To Encrypt /Usr/Dict/Words In About A Second, Peter Su, Matt Bishop Jan 1992

How To Encrypt /Usr/Dict/Words In About A Second, Peter Su, Matt Bishop

Computer Science Technical Reports

We present an implementation of the Data Encryption Standard on the Connection Machine architecture. The DES encryption algorithm is ideally suited to the Connection Machine because it consists of bit serial operations, and thousands of encryptions can be done in parallel, independently of one another. Thus, our code encrypts passwords about ten times faster than the fastest competition that we know about. In addition, the nature of the Connection Machine's architecture is such that some of the optimizations that make DES run much faster on conventional architectures have no effect on the performance of the Connection Machine. Our comparison of …


A Comparison Of The Effects Of Reading From A Vdu And From Paper As Measured In Terms Of Reading Speed And Comprehension, Elizabeth Payumo Jan 1992

A Comparison Of The Effects Of Reading From A Vdu And From Paper As Measured In Terms Of Reading Speed And Comprehension, Elizabeth Payumo

Theses: Doctorates and Masters

This study investigates the legibility and visual effects of eight combinations of font and colour on VDU and two different fonts on paper. Forty subjects, sixteen females and twenty-four males, were exposed to three of the ten different conditions, one in each of the set of readings, on either VDU or paper. They were asked to read different sets of stories in each condition on different days where each condition lasted for approximately two hours. Reading speed and comprehension scores were measured in every story read in the set of stories. The change of mood and physical symptoms states of …


The A.D.E. Taxonomy Of Spreadsheet Application Development, Maria Jean Hall Jan 1992

The A.D.E. Taxonomy Of Spreadsheet Application Development, Maria Jean Hall

Theses: Doctorates and Masters

Spreadsheets are a major application in end-user computing, one of the fastest growing areas of computing. Studies have shown that 30% of spreadsheet applications contain errors. As major decisions are often made with the assistance of spreadsheets, the control of spreadsheet applications is a matter of concern to enduser developers, managers, EDP auditors and computer professionals.

The application of appropriate controls to the spreadsheet development process requires prior categorisation of the spreadsheet application. The special-purpose A.D.E. (Application, Development, Environment) taxonomy of spreadsheet application development was evolved by mathematical taxonomic methods to categorise spreadsheet development projects to facilitate their management and …


A Study Of The Methodologies Currently Available For The Maintenance Of The Knowledge-Base In An Expert System, Kai Teh Jan 1992

A Study Of The Methodologies Currently Available For The Maintenance Of The Knowledge-Base In An Expert System, Kai Teh

Theses: Doctorates and Masters

This research studies currently available maintenance methodologies for expert system knowledge bases and taxonomically classifies them according to the functions they perform. The classification falls into two broad categories. These are: (1) Methodologies for building a more maintainable expert system knowledge base. This section covers techniques applicable to the development phases. Software engineering approaches as well as other approaches are discussed. (2) Methodologies for maintaining an existing knowledge base. This section is concerned with the continued maintenance of an existing knowledge base. It is divided into three subsections. The first subsection discusses tools and techniques which aid the understanding of …


Electronic Branching Ratio Of The Lepton, R. Ammar, Manoj Thulasidas Jan 1992

Electronic Branching Ratio Of The Lepton, R. Ammar, Manoj Thulasidas

Research Collection School Of Computing and Information Systems

Using data accumulated by the CLEO I detector operating at the Cornell Electron Storage Ring, we have measured the ratio R=Γ(τ→eν¯eντ)Γ1 where Γ1 is the τ decay rate to final states with one charged particle. We find R=0.2231±0.0044±0.0073 where the first error is statistical and the second is systematic. Together with the measured topological one-charged-particle branching fraction, this yields the branching fraction of the τ lepton to electrons, Be=0.192±0.004±0.006.


Measurement Of The Tau Lepton Electronic Branching Fraction, D. Akerib, M. Thulasidas Jan 1992

Measurement Of The Tau Lepton Electronic Branching Fraction, D. Akerib, M. Thulasidas

Research Collection School Of Computing and Information Systems

The tau lepton electron branching fraction has been measured with the CLEO II detector at the Cornell Electron Storage Ring as Be=0.1749±0.0014±0.0022, with the first error statistical and the second systematic. The measurement involves counting electron-positron annihilation events in which both taus decay to electrons, and normalizing to the number of tau-pair decays expected from the measured luminosity. Detected photons in these events constitute a definitive observation of tau decay radiation.


Constrained Completion: Theory, Implementation, And Results, Daniel Patrick Murphy Jan 1992

Constrained Completion: Theory, Implementation, And Results, Daniel Patrick Murphy

Doctoral Dissertations

"The Knuth-Bendix completion procedure produces complete sets of reductions but can not handle certain rewrite rules such as commutativity. In order to handle such theories, completion procedure were created to find complete sets of reductions modulo an equational theory. The major problem with this method is that it requires a specialized unification algorithm for the equational theory. Although this method works well when such an algorithm exists, these algorithms are not always available and thus alternative methods are needed to attack problems. A way of doing this is to use a completion procedure which finds complete sets of constrained reductions. …


Query Optimization In Oodb, Hwee Hwa Pang, Hongjun Lu, Beng Chin Ooi Jan 1992

Query Optimization In Oodb, Hwee Hwa Pang, Hongjun Lu, Beng Chin Ooi

Research Collection School Of Computing and Information Systems

In object-oriented databases, relationships are generally maintained explicitly. The partial result of a retrieved object can be used to efficiently retrieve related objects. Instead of optimizing joins as in relational database systems, pointer chasing is optimized in object-oriented database systems. Further, semantics inherent in the object-oriented database, like superclass-subclass relationships and composite-component relationships between object classes, must be realised. In this paper, we describe our initial result in query optimization in an object-oriented database system. Semantic query transformation is used to preprocess the query. semantically optimized query is then translated into a query evaluation plan which comprises method invocations that …


High Performance Memory System Pct:Ep0199134, Robert Iannucci Dec 1991

High Performance Memory System Pct:Ep0199134, Robert Iannucci

Robert A Iannucci

No abstract provided.


On The Dirichlet Problem For The Degenerate Real Monge Ampère Equation, Bert Wachsmuth Dec 1991

On The Dirichlet Problem For The Degenerate Real Monge Ampère Equation, Bert Wachsmuth

Bert Wachsmuth

No abstract provided.


A Capacity Theory Of Comprehension: Individual Differences In Working Memory, Marcel Just, Patricia Carpenter Dec 1991

A Capacity Theory Of Comprehension: Individual Differences In Working Memory, Marcel Just, Patricia Carpenter

Marcel Adam Just

No abstract provided.


Unix And Security: The Influences Of History, Eugene H. Spafford Dec 1991

Unix And Security: The Influences Of History, Eugene H. Spafford

Department of Computer Science Technical Reports

No abstract provided.


Three Letters On Computer Security And Society, Eugene H. Spafford Dec 1991

Three Letters On Computer Security And Society, Eugene H. Spafford

Department of Computer Science Technical Reports

No abstract provided.