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Computer Sciences Commons™

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1997

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Articles 391 - 407 of 407

Full-Text Articles in Computer Sciences

Compositional Programming Abstractions For Mobile Computing, Peter J. Mccann, Gruia-Catalin Roman Jan 1997

Compositional Programming Abstractions For Mobile Computing, Peter J. Mccann, Gruia-Catalin Roman

All Computer Science and Engineering Research

Recent advances in wireless networking technology and the increasing demand for ubiquitous, mobile connectivity demonstrate the importance of providing reliable systems for managing reconfiguration and disconnection of components. Design of such systems requires tools and techniques appropriate to the task. Many formal models of computation, including UNITY, are not adequate for expressing reconfiguration and disconnection and are therefore inappropriate vehicles for investigating the impact of mobility on the construction of modular and composable systems. Algebraic formalisms such as the pi-calculus have been proposed for modeling mobility. This paper addresses the question of whether UNITY, a state-based formalism with a foundation …

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Design And Implementation Of A New Connection Admission Control Algorithm Using A Multistate Traffic Source Model, Robert Engel Jan 1997

Design And Implementation Of A New Connection Admission Control Algorithm Using A Multistate Traffic Source Model, Robert Engel

All Computer Science and Engineering Research

This report develops a practical method for connection admission control in ATM networks. The method is based on a virtual cell loss probability criterion, is designed to handle heterogeneous traffic types and allows each traffic source to be described by an individual finite-state model with as many states as are needed to describe the source traffic. To make connection admission decisions with respect to individual links, an aggregate finite state model is computed from the individual models and used to estimate the virtual cell loss probabilities. To reduce the computational requirements for maintaining the aggregate traffic model, the aggregate model …

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The Design And Performance Of A Real-Time Corba Event Service, Timothy H. Harrison, David L. Levine, Douglas C. Schmidt Jan 1997

The Design And Performance Of A Real-Time Corba Event Service, Timothy H. Harrison, David L. Levine, Douglas C. Schmidt

All Computer Science and Engineering Research

The CORBA Event Service provides a flexible model for asynchronous communication among objects.However, the standard CORBA Event Service specification lacks important features required by real-time applications. For instance, operational flight programs for fighter aircraft have complex real-time processing requirements. This paper describes the design and performance of an object-oriented, real-time implementation of the CORBA Event Service that is designed to meet these requirements. This paper makes three contributions to the design and performance measurement of object-oriented real-time systems. First, it illustrates how to extend the CORBA Event Service so that it is suitable for real-time systems. These extensions support periodic …

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An Error Control Scheme For Large-Scale Multicast Applications, Christos Papadopoulos, Guru Parulkar, George Varghese Jan 1997

An Error Control Scheme For Large-Scale Multicast Applications, Christos Papadopoulos, Guru Parulkar, George Varghese

All Computer Science and Engineering Research

Retransmission based error control for large scale multicast applications is difficult because of two main problems: request implosion and lack of local recovery. Existing schemes (SRM, RMTP, TMTP, LBRRM) have good solutions to request implosion, but only approximate solutions (e.g., based on scoped multicast) for the local recovery problem. Our scheme achieves finer grain fault recovery by exploiting new forwarding services that allow us to create a dynamic hierarchy of receivers. We use a new paradigm, where routers provide a more refined form of multicasting (that may be useful to other applications), that enables local recovery. The new services, however, …

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The Programmers' Playground Application Management System User Guide, William M. Shapiro, T. Paul Mccartney, E.F. Berkley Shands Jan 1997

The Programmers' Playground Application Management System User Guide, William M. Shapiro, T. Paul Mccartney, E.F. Berkley Shands

All Computer Science and Engineering Research

Application Management permits the advertising, launching, and configuring of distributed applications created using the Programmers' Playground. Applications can be documented and made available to end-users through the use of application pages on the World Wide Web. The launching and configuring of applications is performed by a brokerage system consisting of an applicatoin broker and one or more hierarchies of module launchers. This document describes how to setup and use the components of the Application Management system.

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Exact Learning Of Discretized Geometric Concepts, Nader H. Bshouty, Paul W. Goldberg, Sally A. Goldman, H. David Mathias Jan 1997

Exact Learning Of Discretized Geometric Concepts, Nader H. Bshouty, Paul W. Goldberg, Sally A. Goldman, H. David Mathias

All Computer Science and Engineering Research

We first present an algorithm that uses membership and equivalence queries to exactly identify a discretized geometric concept defined by the unioin of m axis-parallel boxes in d-dimensional discretized Euclidean space where each coordinate can have n discrete values. This algorithm receives at most md counterexamples and uses time and membership queries polynomial in m and log(n) for any constant d. Furthermore, all equivalence queries can be formulated as the union of O(mdlog(m)) axis-parallel boxes. Next, we show how to extend our algorithm to efficiently learn, from only equivalence queries, any discretized geometric concept generated from any number of halfspaces …

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Dynamic Flow Switching: A New Communication Service For Atm Networks, Qiyong Bian, Kohei Shimoto, Jonathan Turner Jan 1997

Dynamic Flow Switching: A New Communication Service For Atm Networks, Qiyong Bian, Kohei Shimoto, Jonathan Turner

All Computer Science and Engineering Research

This paper presents a new communication service for ATM networks that provides one-way, adjustable rate, on-demand communication channels. The proposed dynamic flow service is designed to operate within a multi-service cell switched network that supports both conventional switched virtual circuits and IP packet routing and is designed to complement those services. It is particularly well suited to applications that transmit substantial amounts of data (a few tens of kilobytes or more) in fairly short time periods (up to a few seconds). Much of the current world-wide web traffic falls within this domain. Like IP packet networks, the new service permits …

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Sequence Assembly Validation By Restriction Digest Fingerprint Comparison, Eric C. Rouchka, David J. States Jan 1997

Sequence Assembly Validation By Restriction Digest Fingerprint Comparison, Eric C. Rouchka, David J. States

All Computer Science and Engineering Research

DNA sequence analysis depends on the accurate assembly of fragment reads for the determination of a consensus sequence. Genomic sequences frequently contain repeat elements that may confound the fragment assembly process, and errors in fragment assembly, and errors in fragment assembly may seriously impact the biological interpretation of the sequence data. Validating the fidelity of sequence assembly by experimental means is desirable. This report examines the use of restriction digest analysis as a method for testing the fidelity of sequence assembly. Restriction digest fingerprint matching is an established technology for high resolution physical map construction, but the requirements for assembly …

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Reducing Web Latencies Using Precomputed Hints, Girish P. Chandranmenon, George Varghese Jan 1997

Reducing Web Latencies Using Precomputed Hints, Girish P. Chandranmenon, George Varghese

All Computer Science and Engineering Research

Current network technology is bandwidth-rich but latency-poor; thus round-trip delays will dominate access latency for web traffic. We describe four new techniques that reduce the round-trips needed for web accesses. The techniques are based on the paradigm of preprocessing a web page to collect information about links and inline data in the page. Stored Address Binding almost always eliminates the DNS lookup (which can cost seconds) at the start of a transaction. In Informed Server Proxying, a server tells its client that it has cached pages referenced in a page the client just retrieved; this allows the client to retrieve …

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Measurement Of The Τ Lepton Lifetime With The Three-Dimensional Impact Parameter Method, R. Barate, M. Thulasidas Jan 1997

Measurement Of The Τ Lepton Lifetime With The Three-Dimensional Impact Parameter Method, R. Barate, M. Thulasidas

Research Collection School Of Computing and Information Systems

A new method is presented for the measurement of the mean lepton lifetime using events in which are pair-produced and both's decay to hadrons.

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Antiplane Shear Of A Strip Containing A Staggered Array Of Rigid Line Inclusions, G. Kerr, G. Melrose, J. Tweed Jan 1997

Antiplane Shear Of A Strip Containing A Staggered Array Of Rigid Line Inclusions, G. Kerr, G. Melrose, J. Tweed

Mathematics & Statistics Faculty Publications

Motivated by the increased use of fibre-reinforced materials, we illustrate how the effective elastic modulus of an isotropic and homogeneous material can be increased by the insertion of rigid inclusions. Specifically we consider the two-dimensional antiplane shear problem for a strip of material. The strip is reinforced by introducing two sets of ribbon-like, rigid inclusions perpendicular to the faces of the strip. The strip is then subjected to a prescribed uniform displacement difference between its faces, see Figure 1. it should be noted that the problem posed is equivalent to that of the uniform antiplane shear problem for an infinite …

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Improved Measurement Of The Bd0 -B̄D0 Oscillation Frequency, D. Buskulic, M. Thulasidas Jan 1997

Improved Measurement Of The Bd0 -B̄D0 Oscillation Frequency, D. Buskulic, M. Thulasidas

Research Collection School Of Computing and Information Systems

The time dependence of B0 d {B 0 d oscillations is measured by the ALEPH experiment at LEP, using three techniques, two of which are updates of previous measurements. In all cases the charge of the decaying b quark and its decay time are measured in one hemisphere of the event; the quark charge at production is tagged mainly using the opposite hemisphere. The first method uses the charge correlation between a D and a lepton in the opposite hemisphere; if no lepton is present, the produced quark charge is determined from the hemisphere charges. In the second method, the …

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Lyceum: A Multi-Protocol Digital Library Gateway, Ming-Hokng Maa, Michael L. Nelson, Sandra L. Esler Jan 1997

Lyceum: A Multi-Protocol Digital Library Gateway, Ming-Hokng Maa, Michael L. Nelson, Sandra L. Esler

Computer Science Faculty Publications

Lyceum is a prototype scalable query gateway that provides a logically central interface to multi-protocol and physically distributed, digital libraries of scientific and technical information. Lyceum processes queries to multiple syntactically distinct search engines used by various distributed information servers from a single logically central interface without modification of the remote search engines. A working prototype (http://www.larc.nasa.gov/lyceum/) demonstrates the capabilities, potentials, and advantages of this type of meta-search engine by providing access to over 50 servers covering over 20 disciplines.

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Time-Optimal Tree Computations On Sparse Meshes, D. Bhagavathi, V. Bokka, H. Gurla, S. Olariu, J. L. Schwing Jan 1997

Time-Optimal Tree Computations On Sparse Meshes, D. Bhagavathi, V. Bokka, H. Gurla, S. Olariu, J. L. Schwing

Computer Science Faculty Publications

The main goal of this work is to fathom the suitability of the mesh with multiple broadcasting architecture (MMB) for some tree-related computations. We view our contribution at two levels: on the one hand, we exhibit time lower bounds for a number of tree-related problems on the MMB. On the other hand, we show that these lower bounds are tight by exhibiting time-optimal tree algorithms on the MMB. Specifically, we show that the task of encoding and/or decoding n-node binary and ordered trees cannot be solved faster than Ω(log n) time even if the MMB has an infinite …

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Hardware Interfacing In The Broadcast Industry Using Simple Network Management Protocol (Snmp), Walter H. Schuller Jr. Jan 1997

Hardware Interfacing In The Broadcast Industry Using Simple Network Management Protocol (Snmp), Walter H. Schuller Jr.

UNF Graduate Theses and Dissertations

Communication between various broadcast equipment plays a major role in the daily operation of a typical broadcast facility. For example, editing equipment must interface with tape machines, production switchers must interface with font generators and video effect equipment, and satellite ground controllers must interface with satellite dishes and receivers. Communication between these devices may be a simple hardware handshake configuration or a more elaborate software based communications via serial or parallel interfacing. This thesis concerns itself with the software interfacing needed to allow various dissimilar types of equipment to communicate, and therefore, interface with each other. The use of Simple …

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Analysis Of Digital Logic Schematics Using Image Recognition, James A. Giles Jan 1997

Analysis Of Digital Logic Schematics Using Image Recognition, James A. Giles

UNF Graduate Theses and Dissertations

This thesis presents the results of research in the area of automated recognition of digital logic schematics. The adaptation of a number of existing image processing techniques for use with this kind of image is discussed, and the concept of using sets of tokens to represent the overall drawing i s explained in detail. Methods are given for using tokens to describe schematic component shapes, to represent the connections between components, and to provide sufficient information to a parser so that an equation can be generated. A Microsoft Windows-based test program which runs under Windows 95 or Windows NT has …

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Curriculum Development And Evaluation For A Computer Literacy Course, Molly J. Fagan Jan 1997

Curriculum Development And Evaluation For A Computer Literacy Course, Molly J. Fagan

Dissertations and Theses @ UNI

This paper describes a curriculum that was developed and used for a computer literacy course at the University of Northern Iowa. The curriculum included a unit of computer programming, which has not been included as part of the computer literacy course in recent years at the University of Northern Iowa. Surveys were given at the beginning of the semester to determine the approximate level of students' prior knowledge. The same survey was given at the end of the semester and the results of both were compared to see how much more comfortable each individual student felt using the various computer …

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