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1995

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Articles 1741 - 1770 of 2193

Full-Text Articles in Physical Sciences and Mathematics

Formal Specification Of A Dynamically Configurable Distributed System, Ram Sethuraman, Kenneth J. Goldman Jan 1995

Formal Specification Of A Dynamically Configurable Distributed System, Ram Sethuraman, Kenneth J. Goldman

All Computer Science and Engineering Research

The Programmers' Playground is a programming environment that supports end-user construction of distributed multimedia applications. The system implements a new programming model that is based, in part, upon ideas from the formal I/O automaton model of Lynch and Tuttle. Important features of The Programmers' Playground are a separation of communication and computation and graphical support for dynamic reconfiguration. This paper provides a formal specification of the Playground programming model and runtime system in terms of the I/O automaton model on which it is based. Exploiting the compositionality properties of the I/O automaton model, the formal specification is describd as a …

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Redesigning The Bsd Callout And Timer Facilities, Adam M. Costello, George Varghese Jan 1995

Redesigning The Bsd Callout And Timer Facilities, Adam M. Costello, George Varghese

All Computer Science and Engineering Research

We describe a new implementation of the BSD callout and timer facilities. Current BSD kernels take time proportional to the number of outstanding timers to set or cancel timers. Our implementation takes constant time to start, stop, and maintain timers; this leads to a highly scalable design that can support thousands of outstanding timers without much overhead. Unlike the existing implementation, our routines are guaranteed to lock out interrupts only for a small, bounded amount of time. We also extend the setitimer() interface to allow a process to have multiple outstanding timers, thereby reducing the need for users to maintain …

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User Interface Applications Of A Multi-Way Constraint Solver, T. Paul Mccartney Jan 1995

User Interface Applications Of A Multi-Way Constraint Solver, T. Paul Mccartney

All Computer Science and Engineering Research

Constraints are widely recognized as a useful tool for user interface constructino. Through constraints, relationships among user interface components can be defined declaratively, leaving the task of relationship management to a constraint solver. Multi-way constraint solvers supporting constraint hierarchies provide a means to specify preferential constraint relationships with a dynamically changing computation flow, making them especially well suited to interactive user interfaces. However, previous such constraint solvers lack the ability to enforce inequalities or to effectively handle cyclic constraint relationships. These deficiencies limit the problems that could be solved using a constraint-based approach. This paper presents a new algorithm called …

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A General Matrix Iterative Model For Dynamic Load Balancing, Mark A. Franklin, Vasudha Govindan Jan 1995

A General Matrix Iterative Model For Dynamic Load Balancing, Mark A. Franklin, Vasudha Govindan

All Computer Science and Engineering Research

Effective load balancing algorithms are crucial in fully realizing the performance potential of parallel computer systems. This paper proposes a general matrix iterative model to represent a range of dynamic load balancing algorithms. The model and associated performance measures are used to evaluate and compare vairous load balancing algorithms and derive optimal algorithms and associated parameters for a given application and multiprocessor system. The model is parameterized to represent three load balancing algorithms - the random strategy, diffusion and complete redistribution algorithms. The model is validated by comparing the results with measured performance on a realistic workload. The parallel N-body …

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A Survey Of Network Signaling, Dakang Wu Jan 1995

A Survey Of Network Signaling, Dakang Wu

All Computer Science and Engineering Research

Abstract Network signaling is the process of transferring control information among components of a communication network to establish, maintain, and release connections, and to pass the network management information. The rapid evolution in the field of telecommunications has led to the rapid evolution of network signaling. In this paper, we review the evolution of network signaling. We emphasize the concepts and protocols used in modern fast packet switching networks especially in emerging ATM networks.

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Distributed Radiological Multimedia Conferencing, Naeem Bari Jan 1995

Distributed Radiological Multimedia Conferencing, Naeem Bari

All Computer Science and Engineering Research

Distributed Radiological Multimedia Conference (DRMC) is a collaborative imaging/multimedia conferencing tool which allows geographically separated physicians to confer over a shared projection radiograph. DRMC utilizes the advantages of high bandwidth and scalability offered by the new Asynchronous Transfer Mode (ATM) network technology. This application is customized for the high quality of displayed images and rapid response to user requests. It allows conferees to: share a common radiograph; each possess an independently controlled globally visible cursor; be able to point to and outline areas on the image to bring it to the other conferees' attention; and see and hear each other …

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Load Balance Properties Of Distributed Data Layouts For Clustered Mod Servers, Milind M. Buddhikot, Guru Parulkar Jan 1995

Load Balance Properties Of Distributed Data Layouts For Clustered Mod Servers, Milind M. Buddhikot, Guru Parulkar

All Computer Science and Engineering Research

Large scale storage servers that provide location transparent, interactive access to hundreds or thousands of concurrent, independent clients will be important components of hte furture information super-highway infrastructure. Two key requirements of such servers are as follows: support high parallelism and concurrency in data access to allow large number of access to the same or different data. Second, support independent interactive playout control operations such as fast-forward, rewind, slow-play, pause, resume, random access etc. with minimal latency. This paper assumes a distributed storage server architecture consisting of several high performance storage nodes interconnected by a high speed desk area network …

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Reliable Fifo Load Balancing Over Multiple Fifo Channels, Hari Adieseshu, Gurudatta M. Parulkar, George Varghese Jan 1995

Reliable Fifo Load Balancing Over Multiple Fifo Channels, Hari Adieseshu, Gurudatta M. Parulkar, George Varghese

All Computer Science and Engineering Research

Link striping algorithms are often used to overcome transmission bottlenecks in computer networks. However, traidtional striping algorithms suffer from two major disadvantages. They provide inadequate load sharing in the presence of variable length packets, and may result in non-FIFO delivery of data. We describe a new family of link striping algorithms that solve both problems. Our scheme applies to packets at any layer (physical, data, link, network, and transport) that work over multiple FIFO channels. We deal with variable sized packets by showing how a class of fair queueing algorithms can be converted into load sharing algorithms. Our transformation results …

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An Interactive Model Of Teaching, H. David Mathias Jan 1995

An Interactive Model Of Teaching, H. David Mathias

All Computer Science and Engineering Research

Previous teaching models in the learning theory community have been batch models. That is, in these models the teacher has generated a single set of helpful examples to present to the learner. In this paper we present an interactive model in which the learner has the ability to ask queries as in the query learning model of Angluin [1]. We show that this model is at least as powerful as previous teaching models. We also show that anything learnable with queries, even by a randomized learner, is teachable in our model. In all previous teaching models, all classes shown to …

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Time Variability While Training A Parallel Neural Net Network, Tina L. Seawell, Barry L. Kalman Jan 1995

Time Variability While Training A Parallel Neural Net Network, Tina L. Seawell, Barry L. Kalman

All Computer Science and Engineering Research

The algorithmic analysis, data collection, and statistical analysis required to isolate the cause of time variability observed while an Elman style recurrent neural network is trained in parallel on a twenty processor SPARCcenter 2000 is described in detail. Correlations of system metrics indicate the operating system scheduler or an interaction of kernel processes is the most probable explanation for the variability.

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Modeling Cumulative Impacts And The Carrying Capacity Of Small Tidal Creeks And Inlets, Bruce J. Neilson, Carl H. Hershner, Megan K. Greiner Jan 1995

Modeling Cumulative Impacts And The Carrying Capacity Of Small Tidal Creeks And Inlets, Bruce J. Neilson, Carl H. Hershner, Megan K. Greiner

Reports

The purpose of this project was to identify pollutant loading values which might be used as input for a series of water quality models applied to small tidal creeks and inlets in Virginia's coastal plain. The intent was to identify values from literature sources which might be used in application of the models, absent better or more site specific information. Estimates of biological oxygen demand, chemical oxygen demand and fecal coliform loadings were of specific interest.

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Automatic Pcb Inspection Systems, M. Moganti, Fikret Erçal Jan 1995

Automatic Pcb Inspection Systems, M. Moganti, Fikret Erçal

Computer Science Faculty Research & Creative Works

There are more than 50 process steps required to fabricate a printed circuit board (PCB). To ensure quality, human operators simply inspect the work visually against prescribed standards. The decisions made by this labor intensive, and therefore costly, procedure often also involve subjective judgements. Automatic inspection systems remove the subjective aspects and provide fast, quantitative dimensional assessments. Machine vision may answer the manufacturing industry's need to improve product quality and increase productivity. The major limitation of existing inspection systems is that all the algorithms need a special hardware platform to achieve the desired real-time speeds. This makes the systems extremely …

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Student Evaluations Of Teaching Effectiveness: The Interpretation Of Observational Data And The Principle Of Faute De Mieux, B. Burt Gerstman Jan 1995

Student Evaluations Of Teaching Effectiveness: The Interpretation Of Observational Data And The Principle Of Faute De Mieux, B. Burt Gerstman

B. Burt Gerstman

Student opinion surveys are important but widely misunderstood tools for evaluating teaching effectiveness. In this brief review, an analogy is drawn between the use and interpretation of observational data for public health and biomedical research and the use of student opinion data in evaluating teach ing effectiveness. Sources of systematic error in the form of selection bias, information bias, and confounding are defined and illustrated. Original data concerning intermittent "quid pro quo" confounding (i.e., the effect of expected grades on student evaluations of teaching) are presented. Finally, the principle of faute de mieux ("lack of anything better") and the interpretation …

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Graduate Bulletin, 1995-1996 (1995), Moorhead State University Jan 1995

Graduate Bulletin, 1995-1996 (1995), Moorhead State University

Graduate Bulletins (Catalogs)

No abstract provided.

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Molecular Fluorescence Spectroscopy In The Vicinity Of A Microstructure, P.T. Leung, Thomas F. George Jan 1995

Molecular Fluorescence Spectroscopy In The Vicinity Of A Microstructure, P.T. Leung, Thomas F. George

Physics Faculty Publications and Presentations

A brief review is presented on fluorescence spectroscopy of molecules in the vicinity of a microstructure, which could be a surface structure, clustered ions/atoms, a colloidal particle in a solution, or a tip in certain molecular probes. This structure can be viewed as microscopic, mesoscopic or macroscopic, depending on the specific environment in which the molecule is located. An overview is given for selected experimental and theoretical aspects of this phenomenon, emphasizing some of the previous modeling work of the authors. Discussion of possible future attempts to explore the phenomenon in more detail is presented at the end.

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Finding Connected Components On A Scan Line Array Processor, Ronald I. Greenberg Jan 1995

Finding Connected Components On A Scan Line Array Processor, Ronald I. Greenberg

Computer Science: Faculty Publications and Other Works

This paper provides a new approach to labeling the connected components of an n x n image on a scan line array processor (comprised of n processing elements). Variations of this approach yield an algorithm guaranteed to complete in o(n lg n) time as well as algorithms likely to approach O(n) time for all or most images. The best previous solutions require using a more complicated architecture or require Omega(n lg n) time. We also show that on a restricted version of the architecture, any algorithm requires Omega(n lg n) time in the worst case.

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Synthesis Of Model Tripeptides And Approaches To The Preparation Of A Transition State Analogue Of Phosphoramidon, Nadina Monberg Jan 1995

Synthesis Of Model Tripeptides And Approaches To The Preparation Of A Transition State Analogue Of Phosphoramidon, Nadina Monberg

Master's Theses

No abstract provided.

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Critical Energy Of Torus Knots, Fred Hickling, Wesley Davis, Heather Woolverton Jan 1995

Critical Energy Of Torus Knots, Fred Hickling, Wesley Davis, Heather Woolverton

Journal of the Arkansas Academy of Science

The energy of a smoothly parameterized knot y(t) is defined as rr\ i i lp7 \\dn dsdt Jo Jo \||7M-7(0f (D(t(s),T(t))) 2 j\\ds \\dt where D(y (s), y(t)) is the arc length between the two points y (s) and y(t) on the curve. Simple calculus based arguments are used to locate critical values of the energy functional for torus knots. Explicitly the curves given parametrically by °(«*)W = (V2°iSri).JSSBe V2 C s7nS are CriticalP ° intS ° fthe energy functional whenever a and b are relatively prime.

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Scf-Mo Conformational Analysis Of Polycroconaine, T. E. Ezell, Jerry A. Darsey Jan 1995

Scf-Mo Conformational Analysis Of Polycroconaine, T. E. Ezell, Jerry A. Darsey

Journal of the Arkansas Academy of Science

Abinitio calculations at the STO-3G basis set level using GAUSSIAN 92 were conducted on the monomer unit of polycroconaine, a conducting polymer with conductive properties similar to several metals, in order to determine the most probable conformation of the monomer. We also compared the energy difference between the highest occupied and lowest unoccupied molecular orbitals. Successive calculations were performed at dihedral angle intervals of 30° around the central bond of the monomer. Minimum energy was observed at 0° bond rotation, consistent with a theory that the polymer owes many of its conductive properties to a planar configuration in combination with …

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Shock Study In Fully Relativistic Isothermal Flows. Ii, Ruixin Yang, Menas Kafatos Jan 1995

Shock Study In Fully Relativistic Isothermal Flows. Ii, Ruixin Yang, Menas Kafatos

Mathematics, Physics, and Computer Science Faculty Articles and Research

The isothermal shocks and their stabilities in fully relativistic accretion wedge flows onto black holes are studied. The jump condition across the shock is modified by the relativistic effects when the sound speed is comparable to the speed of light. With a new kind of instability analysis, it is found that only one of the two possible shocks is stable. The results are applied to the QPO behavior in galactic black hole candidates such as Cygnus X-1.

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Report To The Colorado Department Of Natural Resources And The State Board Of Land Commissioners, University Of Colorado Boulder. Natural Resources Law Center, Colorado. Department Of Natural Resources, Colorado. State Board Of Land Commissioners Jan 1995

Report To The Colorado Department Of Natural Resources And The State Board Of Land Commissioners, University Of Colorado Boulder. Natural Resources Law Center, Colorado. Department Of Natural Resources, Colorado. State Board Of Land Commissioners

Books, Reports, and Studies

1 v. (various pagings) ; 28 cm

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Conserving Biodiversity On Private Lands, David Farrier, University Of Colorado Boulder. Natural Resources Law Center Jan 1995

Conserving Biodiversity On Private Lands, David Farrier, University Of Colorado Boulder. Natural Resources Law Center

Books, Reports, and Studies

19 p. ; 28 cm

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The Law Of The Colorado River: Coping With Severe Sustained Drought, Lawrence J. Macdonnell, David H. Getches, William C. Hugenberg, Jr., University Of Colorado Boulder. Natural Resources Law Center Jan 1995

The Law Of The Colorado River: Coping With Severe Sustained Drought, Lawrence J. Macdonnell, David H. Getches, William C. Hugenberg, Jr., University Of Colorado Boulder. Natural Resources Law Center

Books, Reports, and Studies

p. 825-836 : map ; 28 cm

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The Synthesis Of Benzophenane 3,5-Dicarboxylic Acid For The Double Capping Of Beta-Cyclodextrin, Jaydee Dones Cabral Jan 1995

The Synthesis Of Benzophenane 3,5-Dicarboxylic Acid For The Double Capping Of Beta-Cyclodextrin, Jaydee Dones Cabral

Dissertations, Theses, and Masters Projects

No abstract provided.

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Runtime And Language Support For Compiling Adaptive Irregular Programs On Distributed Memory Machines, Yuan-Shin Hwang, Bongki Moon, Shamik D. Sharma, Ravi Ponnusamy Jan 1995

Runtime And Language Support For Compiling Adaptive Irregular Programs On Distributed Memory Machines, Yuan-Shin Hwang, Bongki Moon, Shamik D. Sharma, Ravi Ponnusamy

Northeast Parallel Architecture Center

In many scientific applications, arrays containing data are indirectly indexed through indirection arrays. Such scientific applications are called irregular programs and are a distinct class of applications that require special techniques for parallelization. This paper presents a library called CHAOS, which helps users implement irregular programs on distributed-memory message-passing machines, such as the Paragon, Delta, CM-5 and SP-1. The CHAOS library provides efficient runtime primitives for distributing data and computation over processors; it supports efficient index translation mechanisms and provides users high-level mechanisms for optimizing communication. CHAOS subsumes the previous PARTI library and supports a larger class of applications. In …

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Cluster Computing Review, Mark Baker, Geoffrey C. Fox, Hon W. Yau Jan 1995

Cluster Computing Review, Mark Baker, Geoffrey C. Fox, Hon W. Yau

Northeast Parallel Architecture Center

In the past decade there has been a dramatic shift from mainframe or ‘host−centric’ computing to a distributed ‘client−server’ approach. In the next few years this trend is likely to continue with further shifts towards ‘network−centric’ computing becoming apparent. All these trends were set in motion by the invention of the mass−reproducible microprocessor by Ted Hoff of Intel some twenty−odd years ago. The present generation of RISC microprocessors are now more than a match for mainframes in terms of cost and performance. The long−foreseen day when collections of RISC microprocessors assembled together as a parallel computer could out perform the …

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Parallel Remapping Algorithms For Adaptive Problems, Chao Wei Ou, Sanjay Ranka Jan 1995

Parallel Remapping Algorithms For Adaptive Problems, Chao Wei Ou, Sanjay Ranka

Northeast Parallel Architecture Center

In this paper we present fast parallel algorithms for remapping a class of irregular and adaptive problems on coarse-grained distributed memory machines. We show that the remapping of these applications, using simple index-based mapping algorithm, can be reduced to sorting a nearly sorted list of integers or merging an unsorted list of integers with a sorted list of integers. By using the algorithms we have developed, the remapping of these problems can be achieved at a fraction of the cost of mapping from scratch. Experimental results are presented on the CM-5.

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High Performance Distributed Computing, Geoffrey C. Fox Jan 1995

High Performance Distributed Computing, Geoffrey C. Fox

Northeast Parallel Architecture Center

High Performance Distributed Computing (HPDC) is driven by the rapid advance of two related technologies -- those underlying computing and communications, respectively. These technology pushes are linked to application pulls, which vary from the use of a cluster of some 20 workstations simulating fluid flow around an aircraft, to the complex linkage of several hundred million advanced PCs around the globe to deliver and receive multimedia information. The review of base technologies and exemplar applications is followed by a brief discussion of software models for HPDC, which are illustrated by two extremes -- PVM and the conjectured future World Wide …

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Software Tool Evaluation Methodology, Salim Hariri, Sung Yong Park, Rajashekar Reddy, Mahesh Subramanyan Jan 1995

Software Tool Evaluation Methodology, Salim Hariri, Sung Yong Park, Rajashekar Reddy, Mahesh Subramanyan

Northeast Parallel Architecture Center

The recent development of parallel and distributed computing software has introduced a variety of software tools that support several programming paradigms and languages. This variety of tools makes the selection of the best tool to run a given class of applications on a parallel or distributed system a non-trivial task that requires some investigation. We expect tool evaluation to receive more attention as the deployment and usage of distributed systems increases. In this paper, we present a multi-level evaluation methodology for parallel/distributed tools in which tools are evaluated from different perspectives. We apply our evaluation methodology to three message passing …

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Communication Strategies For Out-Of-Core Programs On Distributed Memory Machines, Rajesh Bordawekar, Alok Choudhary Jan 1995

Communication Strategies For Out-Of-Core Programs On Distributed Memory Machines, Rajesh Bordawekar, Alok Choudhary

Northeast Parallel Architecture Center

In this paper, we show that communication in the out-of-core distributed memory problems requires both inter-processor communication and file I/O. Given that primary data structures reside in files, even communication requires I/O. Thus, it is important to optimize the I/O costs associated with a communication step. We present three methods for performing communication in out-of-core distributed memory problems. The first method, termed as the “out-of-core“communication method, follows a loosely synchronous model. Computation and Communication phases in this case are clearly separated, and communication requires permutation of data in files. The second method, termed as”demand-driven-in-core communication” considers only communication required of …

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