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Syracuse University

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Articles 241 - 270 of 532

Full-Text Articles in Computer Sciences

Resource Access Control For An Internet User Agent, Nataraj Nagaratnam, Steven B. Byrne Jan 1997

Resource Access Control For An Internet User Agent, Nataraj Nagaratnam, Steven B. Byrne

Electrical Engineering and Computer Science - All Scholarship

The rapid increase in the Internet's connectivity has lead to proportional increase in the development of Web-based applications. Usage of downloadable content has proved effective in a number of emerging applications including electronic commerce, software components on-demand, and collaborative systems. In all these cases, Internet user agents (like browsers, tuners) are widely used by the clients to utilize and execute such downloadable content. With this new technology of using downloadable content comes the problem of the downloaded content obtaining unauthorized access to the client's resources. In effect, granting a hostile remote principal the requested access to client's resources may lead …

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An Efficient K-Means Clustering Algorithm, Khaled Alsabti, Sanjay Ranka, Vineet Singh Jan 1997

An Efficient K-Means Clustering Algorithm, Khaled Alsabti, Sanjay Ranka, Vineet Singh

Electrical Engineering and Computer Science - All Scholarship

In this paper, we present a novel algorithm for performing k-means clustering. It organizes all the patterns in a k-d tree structure such that one can find all the patterns which are closest to a given prototype efficiently. The main intuition behind our approach is as follows. All the prototypes are potential candidates for the closest prototype at the root level. However, for the children of the root node, we may be able to prune the candidate set by using simple geometrical constraints. This approach can be applied recursively until the size of the candidate set is one for each …

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Webflow - A Visual Programming Paradigm For Web/Java Based Coarse Grain Distributed Computing, Dimple Bhatia, Vanco Burzevski, Maja Camuseva, Geoffrey C. Fox Jan 1997

Webflow - A Visual Programming Paradigm For Web/Java Based Coarse Grain Distributed Computing, Dimple Bhatia, Vanco Burzevski, Maja Camuseva, Geoffrey C. Fox

Northeast Parallel Architecture Center

We present here the recent work at NPAC aimed at developing WebFlow---a general purpose Web based visual interactive programming environment for coarse grain distributed computing. We follow the 3-tier architecture with the central control and integration WebVM layer in tier-2, interacting with the visual graph editor applets in tier-1 (front-end) and the legacy systems in tier-3. WebVM is given by a mesh of Java Web servers such as Jeeves from JavaSoft or Jigsaw from MIT/W3C. All system control structures are implemented as URL-addressable servlets which enable Web browser-based authoring, monitoring, publication, documentation and software distribution tools for distributed computing. We …

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Random Number Generators For Parallel Computers, Paul D. Coddington Jan 1997

Random Number Generators For Parallel Computers, Paul D. Coddington

Northeast Parallel Architecture Center

Random number generators are used in many applications, from slot machines to simulations of nuclear reactors. For many computational science applications, such as Monte Carlo simulation, it is crucial that the generators have good randomness properties. This is particularly true for large-scale simulations done on high-performance parallel computers. Good random number generators are hard to find, and many widely-used techniques have been shown to be inadequate. Finding high-quality, efficient algorithms for random number generation on parallel computers is even more difficult. Here we present a review of the most commonly-used random number generators for parallel computers, and evaluate each generator …

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Java For Parallel Computing And As A General Language For Scientific And Engineering Simulation And Modeling, Geoffrey C. Fox, Wojtek Furmanski Jan 1997

Java For Parallel Computing And As A General Language For Scientific And Engineering Simulation And Modeling, Geoffrey C. Fox, Wojtek Furmanski

Northeast Parallel Architecture Center

We discuss the role of Java and Web technologies for general simulation. We classify the classes of concurrency typical in problems and analyze separately the role of Java in user interfaces, coarse grain software integration, and detailed computational kernels. We conclude that Java could become a major language for computational science, as it potentially offers good performance, excellent user interfaces, and the advantages of object-oriented structure.

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Pcrc-Based Hpf Compilation, Guansong Zhang, Bryan Carpenter, Geoffrey C. Fox, Xiaoming Li Jan 1997

Pcrc-Based Hpf Compilation, Guansong Zhang, Bryan Carpenter, Geoffrey C. Fox, Xiaoming Li

Northeast Parallel Architecture Center

This paper describes an ongoing effort supported by ARPA PCRC (Parallel Compiler Runtime Consortium) project. In particular, we discuss the design and implementation of an HPF compilation system based on PCRC runtime. The approaches to issues such as directive analysis and communication detection are discussed in detail. The discussion includes fragments of code generated by the compiler.

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A Prototype Fortran-To-Java Converter, Geoffrey C. Fox, Xiaoming Li, Zheng Qiang, Wu Zhigang Jan 1997

A Prototype Fortran-To-Java Converter, Geoffrey C. Fox, Xiaoming Li, Zheng Qiang, Wu Zhigang

Northeast Parallel Architecture Center

This is a report on a prototype of a FORTRAN 77 to Java converter, f2j. Translation issues are identified, approaches are presented, a URL is provided for interested readers to download the package, and some unsolved problems are brought up. F2j allows value added to some of the investment onFORTRAN code, in particular, those well established FORTRAN libraries for scientific and engineering computation.

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A Comparison Of Optimization Heuristics For The Data Mapping Problem, Nikos Chrisochoides, Nashat Mansour, Geoffrey C. Fox Jan 1997

A Comparison Of Optimization Heuristics For The Data Mapping Problem, Nikos Chrisochoides, Nashat Mansour, Geoffrey C. Fox

Northeast Parallel Architecture Center

In this paper we compare the performance of six heuristics with suboptimal solutions for the data distribution of two dimensional meshes that are used for the numerical solution of Partial Differential Equations (PDEs) on multicomputers. The data mapping heuristics are evaluated with respect to seven criteria covering load balancing, interprocessor communication, flexibility and ease of use for a class of single-phase iterative PDE solvers. Our evaluation suggests that the simple and fast block distribution heuristic can be as effective as the other five complex and computational expensive algorithms.

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Evaluation Of High Performance Fortran Through Application Kernels, Hon W. Yau, Geoffrey C. Fox, Ken Hawick Jan 1997

Evaluation Of High Performance Fortran Through Application Kernels, Hon W. Yau, Geoffrey C. Fox, Ken Hawick

Northeast Parallel Architecture Center

Since the definition of the High Performance Fortran (HPF) standard, we have been maintaining a suite of application kernel codes with the aim of using them to evaluate the available compilers. This paper presents the results and conclusions from this study, for sixteen codes, on compilers from IBM, DEC, and the Portland Group Inc. (PGI), and on three machines: a DEC Alphafarm, an IBM SP-2, and a Cray T3D. From this, we hope to show the prospective HPF user that scalable performance is possible with modest effort, yet also where the current weaknesses lay.

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Tango - A Collaborative Environment For The World-Wide Web, Lukasz Michal Beca, Gang Cheng, Geoffrey C. Fox, Tomasz Jurga, Konrad Olszewski, Marek Podgorny, Piotr Sokolowski, Tomasz Stachowiak, Krzysztof Walczak Jan 1997

Tango - A Collaborative Environment For The World-Wide Web, Lukasz Michal Beca, Gang Cheng, Geoffrey C. Fox, Tomasz Jurga, Konrad Olszewski, Marek Podgorny, Piotr Sokolowski, Tomasz Stachowiak, Krzysztof Walczak

Northeast Parallel Architecture Center

Geographical and logical growth of the World-Wide Web is accompanied by a fast technological development. Web can be successfully used as a platform for implementation of diverse applications. Distributed and collaborative systems are among the most challenging Web applications. TANGO is an integration platform which enables implementation of Web-based collaborative environments. The system provides means for fast integration of Web- and non-Web-applications into one multi-user collaborative systems. In this paper we describe the functional model, requirements, system design and certain implementation issues of the TANGO system.

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A Compiler Algorithm For Optimizing Locality In Loop Nests, Mahmut Kandemir, J. Ramanujam, Alok Choudhary Jan 1997

A Compiler Algorithm For Optimizing Locality In Loop Nests, Mahmut Kandemir, J. Ramanujam, Alok Choudhary

Electrical Engineering and Computer Science - All Scholarship

This paper describes an algorithm to optimize cache locality in scientific codes on uniprocessor and multiprocessor machines. A distinctive characteristic of our algorithm is that it considers loop and data layout transformations in a unified framework. We illustrate through examples that our approach is very effective at reducing cache misses and tile size sensitivity of blocked loop nests; and can optimize nests for which optimization techniques based on loop transformations alone are not successful. An important special case is the one in which data layouts of some arrays are fixed and cannot be changed. We show how our algorithm can …

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Efficient Heuristic Search Algorithms For Soft-Decision Decoding Of Linear Block Codes, Ching-Cheng Shih, C. R. Wulff, Carlos R.P. Hartmann, Chilukuri K. Mohan Jul 1996

Efficient Heuristic Search Algorithms For Soft-Decision Decoding Of Linear Block Codes, Ching-Cheng Shih, C. R. Wulff, Carlos R.P. Hartmann, Chilukuri K. Mohan

Electrical Engineering and Computer Science - Technical Reports

This paper deals with maximum-likelihood soft-decision decoding as well as suboptimal soft-decision decoding of linear block codes. In this paper we present a novel and efficient hybrid decoding algorithm for (n, k) linear block codes. This algorithm consists of three new decoding algorithms: M A*, H*, and Directed Search. It hybridizes these three algorithms to take advantage of their strengths and make the decoding more efficient. The first algorithm, M A*, is a modified Algorithm A* that conducts a heuristic search through a code tree of the transmitted code when the decoding problem is transformed into a problem of graph-search …

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Probabilistic Analysis Of The Median Rule: Asymptotics And Applications, Anil Ravindran Menon, Kishan Mehrotra, Chilukuri K. Mohan, Sanjay Ranka May 1996

Probabilistic Analysis Of The Median Rule: Asymptotics And Applications, Anil Ravindran Menon, Kishan Mehrotra, Chilukuri K. Mohan, Sanjay Ranka

Electrical Engineering and Computer Science - Technical Reports

The solution of integer optimization problems by relaxation methods consists of three parts. First, the discrete problem is converted into a continuous optimization problem, which is generally more tractable. Second, the relaxed problem is solved efficiently, yielding a optimal solution in the continuous space. Finally, an assignment procedure is used to map this solution to a "suitable" discrete solution. One heuristic - we call it the relaxation heuristic - that often guides the choice and design of assignment algorithms is: "given a continuous optimal solution, the corresponding integer optimal solution is likely to be nearby" (with respect to some well …

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A Library-Based Approach To Task Parallelism In A Data-Parallel Language, Ian Foster, David R. Kohr, Rakesh Krishnaiyer, Alok Choudhary Jan 1996

A Library-Based Approach To Task Parallelism In A Data-Parallel Language, Ian Foster, David R. Kohr, Rakesh Krishnaiyer, Alok Choudhary

College of Engineering and Computer Science - Former Departments, Centers, Institutes and Projects

The data-parallel language High Performance Fortran (HPF) does not allow efficient expression of mixed task/data-parallel computations or the coupling of separately compiled data-parallel modules. In this paper, we show how these common parallel program structures can be represented, with only minor extensions to the HPF model, by using a coordination library based on the Message Passing Interface (MPI). This library allows data-parallel tasks to exchange distributed data structures using calls to simple communication functions. We present microbenchmark results that characterize the performance of this library and that quantify the impact of optimizations that allow reuse of communication schedules in common …

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A Unified Tiling Approach For Out-Of-Core Computations, Rajesh Bordawekar, Alok Choudhary, J. Ramanujam, Mahmut Kandemir Jan 1996

A Unified Tiling Approach For Out-Of-Core Computations, Rajesh Bordawekar, Alok Choudhary, J. Ramanujam, Mahmut Kandemir

College of Engineering and Computer Science - Former Departments, Centers, Institutes and Projects

This paper describes a framework by which an out-of-core stencil program written in a data-parallel language can be translated into node programs in a distributed-memory message-passing machine with explicit I/O and communication. We focus on a technique called Data Space Tiling to group data elements into slabs that can fit into memories of processors. Methods to choose legal tile shapes under several constraints and deadlock-free scheduling of tiles are investigated. Our approach is unified in the sense that it can be applied to both FORALL loops and the loops that involve flow-dependences.

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Shape Recognition Using Genetic Algorithms, Ender Ozcan, Chilukuri K. Mohan Jan 1996

Shape Recognition Using Genetic Algorithms, Ender Ozcan, Chilukuri K. Mohan

College of Engineering and Computer Science - Former Departments, Centers, Institutes and Projects

Shape recognition is a challenging task when shapes overlap, forming noisy, occluded, partial shapes. This paper uses a genetic algorithm for matching input shapes with model shapes described in terms of features such as line segments and angles (extracted using traditional algorithms). The quality of matching is gauged using a measure derived from attributed shape grammars [12, 13]. Preliminary results, using shapes with about 30 features each, are extremely encouraging.

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Unsupervised Algorithms For Learning Emergent Spatio-Temporal Correlations, Chaitanya Tumuluri Jan 1996

Unsupervised Algorithms For Learning Emergent Spatio-Temporal Correlations, Chaitanya Tumuluri

Electrical Engineering and Computer Science - Technical Reports

Many applications require the extraction of spatiotemporal correlations among dynamically emergent features of non-stationary distributions. In such applications it is not possible to obtain an a priori analytical characterization of the emergent distribution. This paper extends the Growing Cell Structures (GCS) network and presents two novel (GIST and GEST) networks, which combine unsupervised feature-extraction and Hebbian learning, for tracking such emergent correlations. The networks were successfully tested on the challenging Data Mapping problem, using an execution driven simulation of their implementation in hardware. The results of the simulations show the successful use of the GIST and GEST networks for extracting …

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The Isomorphism Conjecture Fails Relative To A Random Oracle, Stuart A. Kurtz, Stephen R. Mahaney, James S. Royer Jan 1996

The Isomorphism Conjecture Fails Relative To A Random Oracle, Stuart A. Kurtz, Stephen R. Mahaney, James S. Royer

Electrical Engineering and Computer Science - All Scholarship

Berman and Hartmanis [BH77] conjectured that there is a polynomialtime computable isomorphism between any two languages complete for NP with respect to polynomial-time computable many-one (Karp) reductions. Joseph and Young [JY85] gave a structural definition of a class of NP-complete sets---the k-creative sets---and defined a class of sets (the K k f 's) that are necessarily k-creative. They went on to conjecture that certain of these K k f 's are not isomorphic to the standard NP-complete sets. Clearly, the Berman--Hartmanis and Joseph--Young conjectures cannot both be correct. We introduce a family of strong one-way functions, the scrambling functions. If …

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Every Polynomial-Time 1-Degree Collapses Iff P = Pspace, Stephen A. Fenner, Stuart A. Kurtz, James S. Royer Jan 1996

Every Polynomial-Time 1-Degree Collapses Iff P = Pspace, Stephen A. Fenner, Stuart A. Kurtz, James S. Royer

Electrical Engineering and Computer Science - All Scholarship

A set A is m-reducible (or Karp-reducible) to B iff there is a polynomial-time computable function f such that, for all x, x ∈ A <--> f (x) ∈ B. Two sets are: (a) 1-equivalent iff each is m-reducible to the other by one-one reductions; (b) p-invertible equivalent iff each is m-reducible to the other by one-one, polynomial-time invertible reductions; and (c) p-isomorphic iff there is an m-reduction from one set to the other that is one-one, onto, and polynomial-time invertible. In this paper we show the following characterization. Theorem : The following are equivalent: (a) P = PSPACE. (b) Every …

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Hierarchical Control Flow Graph Models, Douglas G. Fritz, Robert G. Sargent Jan 1996

Hierarchical Control Flow Graph Models, Douglas G. Fritz, Robert G. Sargent

Electrical Engineering and Computer Science - All Scholarship

Hierarchical Control Flow Graph Models define a modeling paradigm for discrete event simulation modeling based upon hierarchical extensions to Control Flow Graph Models. Conceptually, models consist of a set of encapsulated, concurrently operating model components that interact solely via message passing. The primary objectives of Hierarchical Control Flow Graph Models are: (1) to facilitate model development by making it easier to develop, maintain, and reuse models and model elements, and (2) to support the flexible and efficient execution of models. Hierarchical Control Flow Graph Models use two complementary types of hierarchical model specification structures, one to specify components and their …

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Exploration Of Emerging Hpcn Technologies For Web-Based Distributed Computing, Hon W. Yau, Alvin Leung, Wojtek Furmanski, Geoffrey C. Fox Jan 1996

Exploration Of Emerging Hpcn Technologies For Web-Based Distributed Computing, Hon W. Yau, Alvin Leung, Wojtek Furmanski, Geoffrey C. Fox

Northeast Parallel Architecture Center

The surge in the popularity of the World Wide Web (WWW) has corresponded to a decreasing market for specialised high performance computers. This paper discusses how, by making use of technology developed from the broader end of the computing pyramid, much of the past decade's work in distributed computing can be realised in the context of the larger WWW market. Not only do these new technologies offer fresh possibilities, but their pace of development is unlikely to be matched by the traditional high performance research community. A motivating application, discussions of the pertinent emerging technologies, and NPAC's investigations of them, …

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Tests Of Random Number Generators Using Ising Model Simulations, Paul D. Coddington Jan 1996

Tests Of Random Number Generators Using Ising Model Simulations, Paul D. Coddington

Northeast Parallel Architecture Center

Large-scale Monte Carlo simulations require high-quality random number generators to ensure correct results. The contrapositive of this statement is also true – the quality of random number generators can be tested by using them in large-scale Monte Carlo simulations. We have tested many commonly used random number generators with high precision Monte Carlo simulations of the 2-d Ising model using the Metropolis, Swendsen-Wang, and Wolff algorithms. This work is being extended to the testing of random number generators for parallel computers. The results of these tests are presented, along with recommendations for random number generators for high-performance computers, particularly for …

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Array Decompositions For Nonuniform Computational Environments, Maher Kaddoura, Sanjay Ranka, Albert Wang Jan 1996

Array Decompositions For Nonuniform Computational Environments, Maher Kaddoura, Sanjay Ranka, Albert Wang

College of Engineering and Computer Science - Former Departments, Centers, Institutes and Projects

Two-dimensional arrays are useful in a large variety of scientific and engineering applications. Parallelization of these applications requires the decomposition of array elements among different machines. Several data-decomposition techniques have been studied in the literature for machines with uniform computational power. In this paper we develop new methods for decomposing arrays into a cluster of machines with nonuniform computational power. Simulation results show that our methods provide superior decomposition over naive schemes.

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Hierarchical Growing Cell Structures, Vanco Burzevski, Chilukuri K. Mohan Jan 1996

Hierarchical Growing Cell Structures, Vanco Burzevski, Chilukuri K. Mohan

College of Engineering and Computer Science - Former Departments, Centers, Institutes and Projects

We propose a hierarchical self-organizing neural network ("HiGS") with adaptive architecture and simple topological organization. This network combines features of Fritzke's Growing Cell Structures and traditional hierarchical clustering algorithms. The height and width of the tree structure depend on the user-specified level of error desired, and the weights in upper layers of the network do not change in later phases of the learning algorithm. Parameters such as node deletion rate are adaptively modified by the learning algorithm.

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Compile-Time Performance Prediction Of Hpf/Fortran 90d, Manish Parashar, Salim Hariri Jan 1996

Compile-Time Performance Prediction Of Hpf/Fortran 90d, Manish Parashar, Salim Hariri

Electrical Engineering and Computer Science - All Scholarship

In this paper we present an interpretive approach for accurate and cost-effective performance prediction in a high performance computing environment, and describe the design of a compile-time HPF/Fortran 90D performance prediction framework based on this approach. The performance prediction framework has been implemented as a part of the HPF/Fortran 90D application development environment that integrates it with a HPF/Fortran 90D compiler and a functional interpreter. The current implementation of the environment framework is targeted to the iPSC/860 hypercube multicomputer system. A set of benchmarking kernels and application codes have been used to validate the accuracy, utility, and usability of the …

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Snap, Crackle, Webwindows!, Geoffrey C. Fox, Wojtek Furmanski Jan 1996

Snap, Crackle, Webwindows!, Geoffrey C. Fox, Wojtek Furmanski

Northeast Parallel Architecture Center

We elaborate the SNAP---Scalable (ATM) Network and (PC) Platforms---view of computing in the year 2000. The World Wide Web will continue its rapid evolution, and in the future, applications will not be written for Windows NT/95 or UNIX, but rather for WebWindows with interfaces defined by the standards of Web servers and clients. This universal environment will support WebTop productivity tools, such as WebWord, WebLotus123, and WebNotes built in modular dynamic fashion, and undermining the business model for large software companies. We define a layered WebWindows software architecture in which applications are built on top of multi-use services. We discuss …

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A Review Of Commercial And Research Cluster Management Software, Mark Baker, Geoffrey C. Fox, Hon W. Yau Jan 1996

A Review Of Commercial And Research Cluster Management Software, 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 outperform the vector …

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An Application Perspective On High-Performance Computing And Communications, Geoffrey C. Fox Jan 1996

An Application Perspective On High-Performance Computing And Communications, Geoffrey C. Fox

Northeast Parallel Architecture Center

We review possible and probable industrial applications of HPCC focusing on the software and hardware issues. Thirty-three separate categories are illustrated by detailed descriptions of five areas -- computational chemistry; Monte Carlo methods from physics to economics; manufacturing; and computational fluid dynamics; command and control; or crisis management; and multimedia services to client computers and settop boxes. The hardware varies from tightly-coupled parallel supercomputers to heterogeneous distributed systems. The software models span HPF and data parallelism, to distributed information systems and object/data flow parallelism on the Web. We find that in each case, it is reasonably clear that "HPCC works …

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The Distributed Array Descriptor For A Pcrc Hpf Compiler Version 2.0 Sccs-770d, Bryan Carpenter, James Cowie, Donald Leskiw, Xiaoming Li Jan 1996

The Distributed Array Descriptor For A Pcrc Hpf Compiler Version 2.0 Sccs-770d, Bryan Carpenter, James Cowie, Donald Leskiw, Xiaoming Li

Northeast Parallel Architecture Center

We describe a distributed array descriptor that can be used by a runtime supporting HPFlike compilers. This descriptor captures all five types of alignment and BLOCK and CYCLIC distribution as defined in HPF specification. In essence, this descriptor does not distinguish whole array and array sections. Prior to this version, we had versions 1.0, 1.1, and 1.2. This version is not only an update of previous versions, but more importantly it also directly reflects our current practice in an HPF compilation effort.

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A Tale Of Two Applications On The Nii, Geoffrey C. Fox Jan 1996

A Tale Of Two Applications On The Nii, Geoffrey C. Fox

Northeast Parallel Architecture Center

We describe the expected capability of the NII (as an evolution of the Internet) interns of five broad service areas---collaboration, multimedia information dissemination, commerce, metacomputing, and Webtop productivity. We illustrate the demands on these services and the technology implications by examination of two application areas---manufacture of complex systems, such as aircraft and crisis management, command and control.

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