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Articles 12841 - 12870 of 13035

Full-Text Articles in Computer Sciences

The N-Body Problem: Distributed System Load Balancing And Performance Evaluation, Vasudha Govindan, Mark A. Franklin Jan 1993

The N-Body Problem: Distributed System Load Balancing And Performance Evaluation, Vasudha Govindan, Mark A. Franklin

All Computer Science and Engineering Research

In this paper, the N-body simulation problem is considered, its parallel implementation described, its execution time performance is modeled and compared with measured results, and two alternative load balancing algorithms for enhancing performance investigated. Parallel N-body techniques are widely applied in various fields and possess characteristics that challenge the computation and communication capabilities of parallel computing systems and are therefore good candidates for use as parallel benchmarks. Performance models may be used to estimate the performance of an algorithm on a given system, identify performance bottlenecks and study the performance implications of several algorithm are system enhancements. In this paper, …

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Human And Machine Cognition Workshop Papers 1989, 1991, 1993, R. P. Loui Jan 1993

Human And Machine Cognition Workshop Papers 1989, 1991, 1993, R. P. Loui

All Computer Science and Engineering Research

No abstract provided.

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Trainrec: A System For Training Feedforward & Simple Recurrent Networks Efficiently And Correctly, Barry L. Kalman, Stan C. Kwasny Jan 1993

Trainrec: A System For Training Feedforward & Simple Recurrent Networks Efficiently And Correctly, Barry L. Kalman, Stan C. Kwasny

All Computer Science and Engineering Research

TRAINREC is a system for training feedforward and recurrent neural networks that incorporates several ideas. It uses the conjugate-gradient method which is demonstrably more efficient than traditional backward error propagation. We assume epoch-based training and derive a new error function having several desirable properties absent from the traditional sum-of-squared-error function. We argue for skip (shortcut) connections where appropriate and the preference for a sigmoidal yielding values over the [-1,1] interval. The input feature space is often over-analyzed, but by using singular value decomposition, input patterns can be conditioned for better learning often with a reduced number of input units. Recurrent …

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The Programmers' Playground: I/O Abstraction For Heterogeneous Distributed Systems, Kenneth J. Goldman, Michael D. Anderson, Bala Swaminathan Jan 1993

The Programmers' Playground: I/O Abstraction For Heterogeneous Distributed Systems, Kenneth J. Goldman, Michael D. Anderson, Bala Swaminathan

All Computer Science and Engineering Research

I/O abstraction is offered as a new high-level approach to interprocess communication. Functional components of a concurrent system are written as encapsulated modules that act upon local data structures, some of which may be published for external use. Relationships among modules are specified by logical connections among their published data structures. Whenever a module updates published data, I/O takes place implicitly according to the configuration of logical connections. The Programmer's Playground, a software library and run-time system supporting I/O abstraction, is described. Design goals include high-level communication among programs written in multiple programming languages and the uniform treatment of discrete …

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A Design For Reasoning With Policies, Prrecedents And Rationales, Ronald P. Loui, Jeff Norman, Jon Olson, Andrew Merrill Jan 1993

A Design For Reasoning With Policies, Prrecedents And Rationales, Ronald P. Loui, Jeff Norman, Jon Olson, Andrew Merrill

All Computer Science and Engineering Research

No abstract provided.

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Supervised Competitive Learning With Backpropagation Network And Fuzzy Logic, Takayuki Dan Kimura, Thomas H. Fuller Jr., Ce Wang Jan 1993

Supervised Competitive Learning With Backpropagation Network And Fuzzy Logic, Takayuki Dan Kimura, Thomas H. Fuller Jr., Ce Wang

All Computer Science and Engineering Research

SCL assembles a set of learning modules into a supervised learning system to address the stability-plasticity dilemma. Each learning module acts as a similarity detector for a prototype, and includes prototype resetting (akin to that of ART) to respond to new prototypes. Here (Part I) we report SCL results using back-propagation networks as the learning modules. We used two feature extractors: about 30 energy-based features, and a combination of energy-based and graphical features (about 60). ACL recognized 96% (energy) and 99% (energy/graphical) of test digits, and 91% (energy) and 96% (energy/graphical) of test letters. In the accompanying paper (Part II), …

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Approximation Algorithms For Configuring Hierarchical Nonblocking Communication Networks, J. Andrew Fingerhut Jan 1993

Approximation Algorithms For Configuring Hierarchical Nonblocking Communication Networks, J. Andrew Fingerhut

All Computer Science and Engineering Research

A framework is given for specifying nonblocking traffic limits in a connection-oriented communications network. In this framework, connections may be point-to-point or mutlipoint, and the data rates may vary from one connection to another. The traffic limits may be "flat", or they may also be hierarchical, representing communities of interest within the network that have higher traffic among themselves than with the rest of the network. The communication networks are constructed from switches (or nodes) and trunks, which connect pairs of switches. This framework is intended to model Asynchronous Transfer Mode (ATM) networks and traffic. We present a way of …

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Efficiently Computing {Phi}-Nodes On-The-Fly, Ron K. Cytron, Jeanne Ferrante Jan 1993

Efficiently Computing {Phi}-Nodes On-The-Fly, Ron K. Cytron, Jeanne Ferrante

All Computer Science and Engineering Research

Recently, Static Single Assignment Form and Sparse Evaluation Graphs have been advanced for the efficient solution of program optimization problems. Each method is provided with an initial set of flow graph nodes that inherently affect a problem's solution. Other relevant nodes are those where potentially disparate solutions must combine. Previously, these so-called {phi}-nodes were found by computing the iterated dominance frontiers of the initial set of nodes, a process that could take worst case quadratic time with respect to the input flow graph. In this paper we present an almost-linear algorithm for detemining exactly the same set of {phi}-nodes.

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A Taxonomy Of Program Visualization Systems, Gruia-Catalin Roman, Kenneth C. Cox Jan 1993

A Taxonomy Of Program Visualization Systems, Gruia-Catalin Roman, Kenneth C. Cox

All Computer Science and Engineering Research

Program visualization may be viewed as a mapping from programs to graphical representations. This simple idea provides a formal framework for a new taxonomy of program visualization systems. The taxonomy is compared briefly against previous attempts to organize the program visualization field. The taxonomic principles and their motivation are explained in detail with reference to a number of existing systems, especially Balsa, Tango, and Pavane.

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Symphony: A Hardware, Operating System, And Protocol Processing Architecture For Distributed Multimedia Applications, Andreas D. Bovopoulos, R. Gopalakrishnan, Saied Hosseini Jan 1993

Symphony: A Hardware, Operating System, And Protocol Processing Architecture For Distributed Multimedia Applications, Andreas D. Bovopoulos, R. Gopalakrishnan, Saied Hosseini

All Computer Science and Engineering Research

This paper explores the architectural requirements for computers to be able to process multimedia data streams such as video and audio. The I/O subsystem is shown to be a bottleneck, and a network backplane approach is suggested to alleviate this. The need to provide end-to-end performance guarantees requires predictable performance of intra-machine communication, and a schedulable bus with reservation is proposed to achieve this. In addition this requires operating system (OS) mechanisms to negotiate and enforce QoS requirements of applications. A real-time microkernel executive is proposed for each autonomous unit. Requirements for real-time microkernel exeutive is proposed for each autonomous …

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Representing And Learning Propositional Logic In Symmetric Connectionist Networks, Gadi Pinkas Jan 1993

Representing And Learning Propositional Logic In Symmetric Connectionist Networks, Gadi Pinkas

All Computer Science and Engineering Research

The chapter presents methods for efficiently representing logic formulas in connectionist networks that perform energy minimization. Algorithms are given for transforming any formula into a network in linear time and space and for learning representations of unknown formulas by observing examples of satisfying truth assignments. The relaxation process that underlies networks of energy minimization reveals an efficient hill climbing algorithm for satisfiability problems. Experimental results indicate that the parallel implementation of the algorithm with give extremely good average-case performance, even for large-scale, hard satisfiability problems (randomly generated).

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An Optimal Nonblocking Multicast Virtual Circuit Switch, Jonathan S. Turner Jan 1993

An Optimal Nonblocking Multicast Virtual Circuit Switch, Jonathan S. Turner

All Computer Science and Engineering Research

This paper describes an architecture for a multicast virtual circuit switch using cell recycling. This is the first nonblocking switch architecture that is optimal in both the switching network complexity and the amount of memory required for multicast address translation. Furthermore, it is optimal in the amount of effort required for multicast connection modification. This architecture makes it both technically and economically feasible to construct the large switching systems that will ultimately be needed for wide scale deployment of Broadband ISDN to residential users. In particular, we estimate that systems with tens of thousands of 620 Mb/s ports can be …

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Segmentation/Recognition Of Hand-Written Numeral Characters, Khalid Sherdil Jan 1993

Segmentation/Recognition Of Hand-Written Numeral Characters, Khalid Sherdil

All Computer Science and Engineering Research

This thesis describes a number of techniques for segmenting non-cursive handwritten digits into individual characters. It strongly emphasizes on a recognition-segmentation algorithm, which uses the linear regression method to recognize those strokes which consist of one or more straight-lined parts. A new method of sampling the pen data according to the pen speed, hence giving a more uniform points concentratino distribution, is also introduced. It is shown how several of our segmenting techniques, such as relative stroke lengths, relative stroke positions, order of stroke entry, stroke direction, stroke intersection, etc. can be combined to yield success results of about 95%.

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Learning Unions Of Boxes With Membership And Equivalence Queries, Paul W. Goldberg, Sally A. Goldman, H. David Matthias Jan 1993

Learning Unions Of Boxes With Membership And Equivalence Queries, Paul W. Goldberg, Sally A. Goldman, H. David Matthias

All Computer Science and Engineering Research

We present two algorithms that use membership and equivalence queries to exactly identify the concepts given by the union of s discretized axis-parallel boxes in d-dimensional discretized Euclidean space where each coordinate can have n discrete values. The first algorithm receives at most s*d counterexamples and uses time and membership queries polynomial in s and logn for d any constant. Further, all equivalence queries made can be formulated as the union of O(s*d*log(s)) axis-parallel boxes. Next, we introduce a new complexity measure that better captures the complexity of a union of boxes than simply the number of boxes and dimensions. …

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The Washington University Multimedia Explorer, William D. Richard, Jerome R. Cox Jr., A. Maynard Engebretson, Jason Fritts, Craig Horn Jan 1993

The Washington University Multimedia Explorer, William D. Richard, Jerome R. Cox Jr., A. Maynard Engebretson, Jason Fritts, Craig Horn

All Computer Science and Engineering Research

The Washington University MultiMedia eXplorer (MMX) is a complete, host-independent multimedia system capable of transmitting and receiving JPEG-compressed video, CD-quality audio, and high-resolution radiographic images over the Washington University broadband ATM network. If the host is equipped with an ATM interface card, normal network traffic is supported via "T" and "Y" connections. The MMX consists of an ATMizer and three multimedia subsystems. The ATMizer implements the host interface, the interface to the ATM network, and the interface to the three multimdeia channels. This paper describes the architecture of the MMX, the software used with the system, and the applications which …

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A Study Of Dynamic Optimization Techniques: Lessons And Directions In Kernel Design, Calton Pu, Jonathan Walpole Jan 1993

A Study Of Dynamic Optimization Techniques: Lessons And Directions In Kernel Design, Calton Pu, Jonathan Walpole

Computer Science Faculty Publications and Presentations

The Synthesis kernel [21,22,23,27,28] showed that dynamic code generation, software feedback, and fine-grain modular kernel organization are useful implementation techniques for improving the performance of operating system kernels. In addition, and perhaps more importantly, we discovered that there are strong interactions between the techniques. Hence, a careful and systematic combination of the techniques can be very powerful even though each one by itself may have serious limitations. By identifying these interactions we illustrate the problems of applying each technique in isolation to existing kernels. We also highlight the important common under-pinnings of the Synthesis experience and present our ideas on …

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Design And Implementation Of Fuzzy Logic Controllers. Thesis Final Report, 27 July 1992 - 1 January 1993, Osama A. Abihana, Oscar R. Gonzalez Jan 1993

Design And Implementation Of Fuzzy Logic Controllers. Thesis Final Report, 27 July 1992 - 1 January 1993, Osama A. Abihana, Oscar R. Gonzalez

Electrical & Computer Engineering Faculty Publications

The main objectives of our research are to present a self-contained overview of fuzzy sets and fuzzy logic, develop a methodology for control system design using fuzzy logic controllers, and to design and implement a fuzzy logic controller for a real system. We first present the fundamental concepts of fuzzy sets and fuzzy logic. Fuzzy sets and basic fuzzy operations are defined. In addition, for control systems, it is important to understand the concepts of linguistic values, term sets, fuzzy rule base, inference methods, and defuzzification methods. Second, we introduce a four-step fuzzy logic control system design procedure. The design …

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Teaching A Smarter Learner, Sally A. Goldman, H. David Mathias Jan 1993

Teaching A Smarter Learner, Sally A. Goldman, H. David Mathias

All Computer Science and Engineering Research

We introduce a formal model of teaching in which the teacher is tailored to a particular learner, yet the teaching protocol is designed so that no collusion is possible. Not surprisingly, such a model remedies the non-intuitive aspects of otehr models in which the teacher must successfully teach any consistent learner. We prove that any class that can be exactly identified by a deterministic polynomial-time algorithm with access to a very rich set of example-based queries is teachable by a computationally unbounded teacher and a polynomial-time learner. In addition, we present other general results relating this model of teaching to …

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Rule-Maker's And Rule-Follower's Meaning, R. P. Loui Jan 1993

Rule-Maker's And Rule-Follower's Meaning, R. P. Loui

All Computer Science and Engineering Research

No abstract provided.

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The Dim System: Woz Simulation Results - Phase Ii, Anne Johnstone, Umesh Berry, Tina Nguyen Jan 1993

The Dim System: Woz Simulation Results - Phase Ii, Anne Johnstone, Umesh Berry, Tina Nguyen

All Computer Science and Engineering Research

We report an experiment designed to compare human-human spoken dialogues with human-computer spoken dialogue. Our primary purpose was to collect data on the kinds of protocols that were used to control the interaction. Three groups of 12 subjects each were asked to complete tasks over the phone. These tasks involved the use of custom-calling features such as call-forwarding and speed-dialing. The experimental procedure was a new variation on the Wizard of Oz (WOZ) technique that allowed much clearer comparisons to be made between human-human and human-computer interactions. Subjects in the Operator Group were told they were talking to a human …

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Clocked And Asynchronous Instruction Pipelines, Mark A. Franklin, Tienyo Pan Jan 1993

Clocked And Asynchronous Instruction Pipelines, Mark A. Franklin, Tienyo Pan

All Computer Science and Engineering Research

Clocked (synchronous) and self-timed (asynchronous) represent the two prinicipal methodologies associated with timing control and synchronization of digital systems. In this paper, clocked and the asynchronous instruction pipelines are modeled and compared. The approach which yields the best performance is dependent on technology parameters, operating range and pipeline algorithm characteristics. Design curves are presented which permit selection of the best approach for a given application and technology environment.

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Clinical Decision-Support Systems In Radiation Therapy, Nilesh L. Jain, Michael G. Kahn Jan 1993

Clinical Decision-Support Systems In Radiation Therapy, Nilesh L. Jain, Michael G. Kahn

All Computer Science and Engineering Research

Computers have been used in radiation therapy since the early 1960s to perform dose calculations. In the last decade, researchers have developed computer-based clinical decision-support systems for assisting in different decision-making tasks in radiation therapy. This paper reviews eleven prototype systems developed for target volume delineation, treatment planning, treatment plan evaluation, and treatment machine diagnosis. The advent of three-dimensional (3D) conformal radiation therapy (CRT) provides radiation oncologists with the opportunity to consider innovative beam arrangements which were not possible in two-dimensional class solutions. The difficulty of manually generating the thousands of clinically plausible 3D treatment plans calls for the use …

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The Dim System: Turn-Taking In Dyadic Telephone Dialogues, Umesh Berry, Anne Johnstone Jan 1993

The Dim System: Turn-Taking In Dyadic Telephone Dialogues, Umesh Berry, Anne Johnstone

All Computer Science and Engineering Research

The analysis of human conversations has revealed that the design of interfaces using spoken dialogue must differ radically from those using written communication. Such characteristics as prosody, confirmations, echoes, and other speech phenomena must be considered. This work is a step in that direction. Prosodic, syntactic and semantic information from actual human dialogues has been used to build a turn-taking model empirically for dydadic telephone dialogues. The ability to predict completion of turns has been the biggest motivating factor in the development of this model. The design and evaluation of the model are presented in this report.

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Asking Questions To Minimize Errors, Nader H. Bshouty, Sally A. Goldman, Thomas R. Hancock, Sleiman Matar Jan 1993

Asking Questions To Minimize Errors, Nader H. Bshouty, Sally A. Goldman, Thomas R. Hancock, Sleiman Matar

All Computer Science and Engineering Research

A number of efficient learning algorithms achieve exact identification of an unknown function from some clas using membership and equivalence queries. Using a standard transformation such algorithms can easily be converted to on-line learning algorithms that use membership queries. Under such a transformation the number of equivalence queries made by the query algorithm directly corresponds to the number of mistakes made by the on-line algorithm. In this paper we consider several of the natural classes known to be learnable in this setting, and investigate the minimum number of equivalence queries with accompanying counterexamples (or equivalently the minimum number of mistakes …

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Effective Loss Of Multiplexed Atm Cell Streams, Seyyed M-R Mahdavian, Andreas D. Bovopoulos Jan 1993

Effective Loss Of Multiplexed Atm Cell Streams, Seyyed M-R Mahdavian, Andreas D. Bovopoulos

All Computer Science and Engineering Research

Cell loss is an inherent problem of ATM networks. The magnitude of the service degeneration caused by cell loss depends on the application and loss distribution. This paper introduces a new performance criterion, called effective loss, which can quantitatively measure this degradation. Effective loss is particularly suitable for block-oriented transmissions, such as file transfer applications, but can also be applied to a broad range of other applications. In this paper the effective loss measure is applied to the study of the effectiveness of bandwidth reservation mechanisms in an ATM multiplexer. Numerical results demonstrate circumstances under which bandwidth reservation improves performance …

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Distributed Computing Systems And Checkpointing, Ken Wong, Mark Franklin Jan 1993

Distributed Computing Systems And Checkpointing, Ken Wong, Mark Franklin

All Computer Science and Engineering Research

This paper examines the performance of synchronous checkpointing in a distributed computing environment with and without load redistribution. Performance models are developed, and optimum checkpoint intervals are determined. The analysis extends earlier work by allowing for multiple nodes, state dependent checkpoint intervals, and a performance metric which is coupled with failure-free performance and the speedup functions associated with implementation of parallel algorithms. Expressions for the optimum checkpoint intervals for synchronous checkpointing with and without load redistribution are derived and the results are then used to determine when load redistribution is advantageous.

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Dna Mapping Algorithms: Synchronized Double Digest Mapping, Jim Daues, Will Gillett Jan 1993

Dna Mapping Algorithms: Synchronized Double Digest Mapping, Jim Daues, Will Gillett

All Computer Science and Engineering Research

A technique called Synchronized Double Digest Mapping (SDDM) is presented; it combines classical Double Digest Mapping (DDM) and Multiple-Restriction-Enzyme Mapping (MREM). Classical DDM is a technique for determining the order of restriction fragments in a clone given three digestions of the clone: a digestion by enzyme1, a digestion by enzyme2, and a digestion by enzyme1 and enzyme2 combined. All algorithms for applying this technique are exponential (in the number of fragments present in the clone) in nature. MREM is an extension of classical high-resolution restriction-fragment mapping of a YAC or a genome, in which the overlaps among a set of …

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Observation Of The Charmed Baryon C+ And Measurement Of The Isospin Mass Splittings Of The C, Crawford, G.; Et Al., M. Thulasidas Jan 1993

Observation Of The Charmed Baryon C+ And Measurement Of The Isospin Mass Splittings Of The C, Crawford, G.; Et Al., M. Thulasidas

Research Collection School Of Computing and Information Systems

No abstract provided.

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A Comparison Of Queueing, Cluster And Distributed Computing Systems, Joseph A. Kaplan, Michael L. Nelson Jan 1993

A Comparison Of Queueing, Cluster And Distributed Computing Systems, Joseph A. Kaplan, Michael L. Nelson

Computer Science Faculty Publications

Using workstation clusters for distributed computing has become popular with the proliferation of inexpensive, powerful workstations. Workstation clusters offer both a cost effective alternative to batch processing and an easy entry into parallel computing. However, a number of workstations on a network does not constitute a cluster. Cluster management software is necessary to harness the collective computing power. A variety of cluster management and queuing systems are compared: Distributed Queueing Systems (DQS), Condor, Load Leveler, Load Balancer, Load Sharing Facility (LSF - formerly Utopia), Distributed Job Manager (DJM), Computing in Distributed Networked Environments (CODINE), and NQS/Exec. The systems differ in …

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Intel Nx To Pvm 3.2 Message Passing Conversion Library, Trey Arthur, Michael L. Nelson Jan 1993

Intel Nx To Pvm 3.2 Message Passing Conversion Library, Trey Arthur, Michael L. Nelson

Computer Science Faculty Publications

NASA Langley Research Center has developed a library that allows Intel NX message passing codes to be executed under the more popular and widely supported Parallel Virtual Machine (PVM) message passing library. PVM was developed at Oak Ridge National Labs and has become the defacto standard for message passing. This library will allow the many programs that were developed on the Intel iPSC/860 or Intel Paragon in a Single Program Multiple Data (SPMD) design to be ported to the numerous architectures that PVM (version 3.2) supports. Also, the library adds global operations capability to PVM. A familiarity with Intel NX …

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