Computer Sciences Commons^™

Vertex-Edge Pseudo-Visibility Graphs: Characterization And Recognition, Joseph O'Rourke, Ileana Streinu

Computer Science: Faculty Publications

We extend the notion of polygon visibility graphs to pseudo-polygons defined on generalized configurations of points. We consider both vertex-to-vertex, as well as vertex-to-edge visibility in pseudo-polygons. We study the characterization and recognition problems for vertex-edge pseudo-visibility graphs. Given a bipartite graph G satisfying three simple properties, which can all be checked in polynomial time, we show that we can define a generalized configuration of points and a pseudo-polygon on it, so that its vertex-edge pseudo-visibility graph is G. This provides a full characterization of vertex-edge pseudo-visibility graphs and a polynomial-time algorithm for the decision problem. It also implies that …

Webassess, Justin Anthony Brown

Theses : Honours

This project and research has resulted in the development of a World Wide Web (WWW) based testing system. WEBassess can be accessed and used from any point in the world that has a connection to the WWW. The WEBassess system allows for the creation and completion of tests through the WWW interface. Scoring and feedback of submitted tests is completely automated, allowing students to see their test result immediately, including visual indicators for correct and incorrect answers. These test results may then be viewed by academic staff, showing complete test details, such as unit code, test title, score, percentage, date …

Adaptive Multicast Routing In Wormhole Networks, Ran Libeskind-Hadas, Tom Hehre '96, Andrew Hutchings '98, Mark Reyes '98, Kevin Watkins '97

All HMC Faculty Publications and Research

Multicast communication has applications in a number of fundamental operations in parallel computing. An effective multicast routing algorithm must be free from both livelock and deadlock while minimizing communication latency. We describe two classes of multicast wormhole routing algorithms that employ the multi-destination wormhole hardware mechanism proposed by Lin et al. [12] and Panda et al. [17]. Specific examples of these classes of algorithms are described and experimental results suggests that such algorithms enjoy low communication latencies across a range of network loads.

A Concurrency Control Algorithm For An Open And Safe Nested Transaction Model, Sanjay Kumar Madria

Computer Science Faculty Research & Creative Works

We present a concurrency control algorithm for an open and safe nested transaction model. We use prewrite operations in our model to increase the concurrency. Prewrite operations are modeled as subtransactions in the nested transaction tree. The subtransaction which initiates prewrite subtransactions are modelled as recovery point subtransaction. The recovery point subtransaction can release their locks before its ancestors commit. Thus, our model increases the concurrency in comparison to other nested transaction models. Our model is useful an environment of long-running transactions common in object oriented databases, computer aided design and in the software development process

Timestamp-Based Approach For The Detection And Resolution Of Mutual Conflicts In Distributed Systems, Sanjay Kumar Madria

Computer Science Faculty Research & Creative Works

We present a timestamp based algorithm for the detection of both write-write and read-write conflicts for a single file in distributed systems during network partitions. Our algorithm allows operations to occur in different network partitions simultaneously. When the sites from different partitions merge, the algorithm detects and resolves both read-write and write-write conflicts without taking into account the semantics of the transactions. Once the conflicts have been detected some reconciliation steps for the resolution of conflicts have also been proposed. Our algorithm will be useful in real-time systems where timeliness of operations is more important than response time (delayed commit)

The Effects Of User Interface Metaphors On The Learnability Of Computer Systems By Field Dependent And Field Independent Computer Users, Robert N. Urwiler Jr.

CCAC Theses and Dissertations

This study was designed to assess the differences in the learning performance (speed and accuracy) with which field dependent and field independent subjects could complete a set of checkbook management tasks using software employing a user interface making strong use of common checkbook management metaphors versus software employing an interface adhering to a defacto industry standard-based graphical user interface design guideline. It was hypothesized that both field dependent and field independent users would complete tasks more quickly and accurately using both user interface types.

From a population of traditional and non-traditional college students, 64 individuals volunteered to participate in the …

The Topology Dependence Of Charged Particle Multiplicities In Three-Jet Events, R. Barate, M. Thulasidas

Research Collection School Of Computing and Information Systems

A study of individual jet and whole-event charged particle multiplicities in three-jet events measured in e + e − annihilation at the Z reveals a significant topology dependence. Mean jet multiplicities are inadequately described by jet energies; interjet angles must also be specified. Quantitative tests suggest that it is necessary to use transversemomentum- like scales to describe the data.

A Study Of Τ Decays Involving Η And Ω Mesons, D. Buskulic, M. Thulasidas

Research Collection School Of Computing and Information Systems

The 132 pbt - 1 of data collected by ALEPH from 1991 to 1994 have been used to analyze η and ω production in τ decays. The following branching fractions have been measured: B(τ−→ντωh−)=(1.91±0.07±0.06)×10−2,B(τ−→ντωh−)=(1.91±0.07±0.06)×10−2, B(τ−→ντωh−π0)=(4.3±0.6±0.5)×10−3,B(τ−→ντωh−π0)=(4.3±0.6±0.5)×10−3, B(τ−→ντηK−)=(2.9+1.3−1.2±0.7)×10−4,B(τ−→ντηK−)=(2.9−1.2+1.3±0.7)×10−4, B(τ−→ντηh−π0)=(1.8±0.4±0.2)×10−3B(τ−→ντηh−π0)=(1.8±0.4±0.2)×10−3 and the 95% C.L. limit B(τ− → ντηπt -) t - 4 has been obtained. The ωπt- and ηπt -π0 rates and dynamics are found in agreement with the predictions made from e+e∼ - annihilation data with the help of isospin invariance (CVC).

Response Surface Methodology: An Analytical Method For Locating Migrated Contaminant Sources, Orlando J. Dona Jr.

Theses and Dissertations

The use and storage of hazardous chemicals at U.S. military facilities often adversely affect the groundwater when contaminants infiltrate the subsurface as a result of leaks and accidental spills. These contaminants, if not located and remediated in a relatively short time, may move and settle unpredictably, essentially creating a source some distance from the original leak or spill. An example of this phenomenon is found with migrating dense nonaqueous phase liquid (DNAPL) contaminants. Although various methods for estimating the present day locations of these migrated contaminants are in use, accurately pinpointing the source of contaminants remains a difficult problem in …

The Effects Of Human-Computer Communication Mode, Task Complexity, And Desire For Control On Performance And Discourse Organization In An Adaptive Task, Cristina Bubb-Lewis

Psychology Theses & Dissertations

The present study examined how different communication patterns affected task performance with an adaptive interface. A Wizard-of-Oz simulation (Gould, Conti, & Hovanyecz, 1983) was used to create the impression of a talking and listening computer that acted as a teammate to help participants interact with a computer application.

Four levels of communication mode were used which differed in the level of restriction placed on human-computer communication. In addition, participants completed two sets of tasks (simple and complex). Further, a personality trait, Desire for Control (DC), was measured and participants were split into high and low groups for analysis. Dependent measures …

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, Volume 13, Number 1, January 1997, College Of Engineering And Computer Science, Wright State University

BITs and PCs Newsletter

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

Multiprocessor Out-Of-Core Ffts With Distributed Memory And Parallel Disks, Thomas H. Cormen, Jake Wegmann, David M. Nicol

Computer Science Technical Reports

This paper extends an earlier out-of-core Fast Fourier Transform (FFT) method for a uniprocessor with the Parallel Disk Model (PDM) to use multiple processors. Four out-of-core multiprocessor methods are examined. Operationally, these methods differ in the size of "mini-butterfly" computed in memory and how the data are organized on the disks and in the distributed memory of the multiprocessor. The methods also perform differing amounts of I/O and communication. Two of them have the remarkable property that even though they are computing the FFT on a multiprocessor, all interprocessor communication occurs outside the mini-butterfly computations. Performance results on a small …

Learning In A Fuzzy Logic Robot Controller, Doug Blank, J. O. Ross

Computer Science Faculty Research and Scholarship

No abstract provided.

Development And Evaluation Of Interactive Courseware For Visualization Of Graph Data Structure And Algorithms, Thomas E. Beutel

CCAC Theses and Dissertations

The primary goal of this dissertation was to develop and pilot test interactive, multimedia courseware which would facilitate learning the abstract structures, operations, and concepts associated with graph and network data structures in Computer Science. Learning objectives and prerequisites are presented in an introduction section of the courseware and a variety of learning activities are provided including tutorials, animated demonstrations, interactive laboratory sessions, and self-tests. Courseware development incorporated principles and practices from software engineering, instructional design, and cognitive learning theories. Implementation utilized an easy-to-use authoring tool, NeoBook Professional (1994), to create the overall framework and the user interfaces, and Microsoft …

A Proposed Solution For Word-Recognition Deficit In The Computer Environment, Hyacinth Williams

CCAC Theses and Dissertations

Most college students with reading disabilities have difficulty with word recognition. The purpose of this study was to use an investigator-made cue word list to increase low word recognition skills among college students while creating slides for a university curriculum using a simple presentation tool. The investigator randomly divided fourteen subjects into two groups. One group received the treatment and the other did not. Subjects received fifty minutes to complete a five-slide presentation. The investigator used four different data collection processes for data collection. Beyond this, the investigator presented the results using rank correlation. Results from this study indicated that …

Optimizing The Performance Of The Corba Internet Inter-Orb Protocol Over Atm, Aniruddha Gokhale, Douglas C. Schmidt

All Computer Science and Engineering Research

The Internet Inter-ORB Protocol (IIOP) enables heterogeneous CORBA-compliant Object Request Brokers (ORBs) to interoperate over TCP/IP networks. The IIOP uses the Common Data Representation (CDR) transfer syntax to map CORBA Interface Definition Langauge (IDL) data types into a bi-canonical wire format. Due to the excessive marshaling/demarshaling overhead, data copying, and high-levels of function call overhead, conventional implementation of IIOP protocols yield poor performance over high-speed networks. To meet the demands of emerging distributed multimedia applications, CORBA-compliant ORBs must support both interoperable and highly efficient IIOP implementations. This paper provides two contributions to the study and design of high performance CORBA …

Expressing Code Mobility In Mobile Unity, Gian Pietro Picco, Gruia-Catalin Roman, Peter J. Mccann

All Computer Science and Engineering Research

Advancements in network technology have led to the emergence of new computing paradigms that challenge established programming practices by employing weak forms of consistency and dynamic forms of binding. Code mobility, for instance, allows for invocation-time binding between a code fragment and the location where it executes. Similarly, mobile computing allows hosts (and the software they execute) to alter their physical location. Despite apparent similarities, the two paradigms are distinct in their treatment of location and movement. This paper seeks to uncover a common foundation for the two paradigms by exploring the manner in which stereotypical forms of code mobility …

Symmetrical Routes And Reverse Path Congestion Control, Rajib Ghosh, George Varghese

All Computer Science and Engineering Research

We describe new mechanisms to deal with asymmetries that arise in routing protocols. We show how to avoid route asymmetries (due to non-unique shortest paths) by adding random integer link costs. We show in detail how RIP can be modified to avoid route asymmetry with high probability, without affecting either its efficiency or performance metrics such as convergence time. Symmetrical intra-domain routing also makes possible a new form of congestion control that we call Reverse Path Congestion Control (RPCC). We show, using simulations, that RPCC can augment existing TCP congestion control mechanisms to improve start up behavior and to avoid …

End-User Visualization And Manipulation Of Distributed Aggregate Data, T. Paul Mccartney, Kenneth J. Goldman

All Computer Science and Engineering Research

Aggregate visualization and manipulation enables the viewing and interaction of dynamically changing data sets in a graphically meaningful way. However, off-the-shelf applications typically provide only limited ways to view static aggregates and generally to not support manipulation of aggregate data through the resulting visualization. To be fully dynamic, an aggregate visualization should be customizable to suit the individual's needs and should allow end-users to modify the data through direct manipulation. This paper describes a software system that empowers end-users to create interactive aggregate visualizations through a visual language interface. Included are mechanisms for specifying how aggregate data is processed from …

Reasoning About Code Mobility With Mobile Unity, Gian Pietro Picco, Gruia-Catalin Roman, Peter J. Mccann

All Computer Science and Engineering Research

Advancements in network technology have led to the emergence of new computing paradigms that challenge established programming practices by employing weak forms of consistency and dynamic forms of binding. Code mobility, for instance, allows for invocation-time binding between a code fragment and the location where it executes. Similarly, mobile computing allows hosts (and the software they execute) to alter their physical location. Despite apparent similarities, the two paradigms are distinct in their treatment of location and movement. This paper seeks to uncover a common foundation for the two paradigms by exploring the manner in which stereotypical forms of code mobility …

Using Snapshot Streams To Support Visual Exploration, Delbert Hart, Eileen Kraemer, Gruia-Catalin Roman

All Computer Science and Engineering Research

The non-determinism, complexity, and size of distributed software systems present significant difficulties for designers and maintainers. Visualization can help alleviate these difficulties through interactive exploratory tools that allow both novice and experienced users to investigate a distributed computation using a common tool set. Essential to the success of a visual exploration tool is the ability to provide accurate representations of global states. This paper is concerned with the use of snapshots in support of interactive visual exploration of distributed computations. The nature of the visualization process requires snapshots that (1) are consecutive, thus facilitating smooth animation of state changes, (2) …

Mobile Unity: A Language And Logic For Concurrent Mobile Systems, Peter J. Mccann, Gruia-Catalin Roman

All Computer Science and Engineering Research

Traditionally, a distributed system has been viewed as a collection of fixed computational elements connected by a static network. Prompted by recent advances in wireless communications rechnology, the emerging field of mobile computing is challenging these assumptions by providing mobile hosts with connectivity that may change over time, raising the possibility that hosts may be called upon to operate while only weakly connected to or while completely disconnected from other hosts. We define a concurrent mobile system as one where independently executing coponents may migrate through some space during the course of the computation, and where the pattern of connectivity …

Architectural Choices In Large Scale Atm Switches, Jonathan Turner, Naoaki Yamanaka

All Computer Science and Engineering Research

The rapid development of Asynchronous Transfer Mode technology in the last 10-15 years has stimulated renewed interest in the design and analysis of switching systems, leading to new ideas for system designs and new insights into the performance and evaluation of such systems. As ATM moves closer to realizing the vision of ubiquitous broadband ISDN services, the design of switching systems takes on growing importance. This paper seeks to clarify the key architectural issues for ATM switching system design and provides a survey of the current state-of-the-art.

Dialogue And Deliberation, Ronald P. Loui, Diana M. Moore

All Computer Science and Engineering Research

Formal accounts of negotiation tend to invoke the strategic models of conflict which have been impressively developed by game theorists in this half-century. For two decades, however, research on artificial intelligence (AI) has produced a different formal picture of the agent and of the rational deliberations of agents. AI's models are not based simply on intensities of preference and quantities of probability. AI's models consider that agents use language in various ways, that agents use and convey knowledge, that agents plan, search, focus, and argue. Agents can choose their language, apply their knowledge, change their plans, continue their search, shift …

Noise-Tolerant Parallel Learning Of Geometric Concepts, Nader H. Bshouty, Sally A. Goldman, H. David Mathias

All Computer Science and Engineering Research

We present several efficient parallel algorithms for PAC-learning geometric concepts in a constant-dimensional space. The algorithms are robust even against malicious classification noise of any rate less than 1/2. We first give an efficient noise-tolerant parallel algorithm to PAC-learn the class of geometric concepts defined by a polynomial number of (d-1)-dimensional hyperplanes against an arbitrary distribution where each hyperplane has a slope from a set of known slopes. We then describe how boosting techniques can be used so that our algorithms' dependence on {GREEK LETTER} and {DELTA} does not depend on d. Next we give an efficient noise-tolerant parallel algorithm …

Alchourron's Defeasible Conditionals And Defeasible Reasoning, Fernando Tohme, Ronald P. Loui

All Computer Science and Engineering Research

No abstract provided.

Eliding The Arguments Of Cases, Ronald P. Loui, Jeff Norman

All Computer Science and Engineering Research

No abstract provided.

End-User Visualization And Manipulation Of Aggregate Data, T. Paul Mccartney, Kenneth J. Goldman

All Computer Science and Engineering Research

Aggregate visualization and manipulation enables the viewing and interaction of dynamically changing data sets in a graphically meaningful way. However, off-the-shelf applications generally provide only limited ways to view aggregates. To be truly effective to the end-user, an aggregate visualization should be customizable to suit the individual's needs. This paper describes a software system that empowers end-users to create interactive aggregate visualizations through direct manipulation. Included are mechanisms for specifying how aggregate data is processed from multiple sources, providing functionality similar to project, select, join, and cross product of relational databases. Visualization of distributed data sets is emphasized.

Euphoria Reference Manual, T. Paul Mccartney, Kenneth J. Goldman

All Computer Science and Engineering Research

EUPHORIA is a user interface management system that enables end-users to create direct manipulation graphical user interfaces (GUIs) through interactive drawing. Used in conjunction with The Programmers' Playground, a distributed programming environment, end-users can dynamically create and associate GUI components with an underlying application without programming, This document describes EUPHORIA's functionality.

Building Interactive Distributed Applications In C++ With The Programmers' Playground, Kenneth J. Goldman, Joe Hoffert, T. Paul Mccartney, Jerome Plun, Todd Rogers

All Computer Science and Engineering Research

The objective of The Programmers' Playground, described in this manual, is to provide a development environment and underlying support for end-user construction of distributed multimedia applications from reusable self-describing software components. Playground provides a set of software tools and a methodology for simplifying the design and construction of applications that interact with each other and with people in a distributed computer system. This manual explains how to write interactive distributed applications using Playground. The only background necessary to get started is an understanding of basic data structures and control constructs in C++. If you already know C++, then with the …