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Physical Sciences and Mathematics Commons™

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Computer Sciences

Syracuse University

1997

Articles 1 - 26 of 26

Full-Text Articles in Physical Sciences and Mathematics

A One-Pass Algorithm For Accurately Estimating Quantiles For Disk-Resident Data, Khaled Alsabti, Sanjay Ranka, Vineet Singh Jan 1997

A One-Pass Algorithm For Accurately Estimating Quantiles For Disk-Resident Data, Khaled Alsabti, Sanjay Ranka, Vineet Singh

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

The '-quantile of an ordered sequence of data values is the element with rank ' \Theta n, where n is the total number of values. Accurate estimates of quantiles are required for the solution of many practical applications. In this paper, we present a new algorithm for estimating the quantile values for disk-resident data. Our algorithm has the following characteristics: (1) It requires only one pass over the data; (2) It is deterministic; (3) It produces good lower and upper bounds of the true values of the quantiles; (4) It requires no a priori knowledge of the distribution of the …

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A Load Balancing Technique For Multiphase Computations, Jerrell Watts, Marc Rieffel, Stephen Taylor Jan 1997

A Load Balancing Technique For Multiphase Computations, Jerrell Watts, Marc Rieffel, Stephen Taylor

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

Parallel computations comprised of multiple, tightly interwoven phases of computation may require a different approach to dynamic load balancing than single-phase computations. This paper presents a load sharing method based on the view of load as a vector, rather than as a scalar. This approach allows multiphase computations to achieve higher efficiency on large-scale multicomputers than possible with traditional techniques. Results are presented for two large-scale particle simulations running on 128 nodes of an Intel Paragon and on 256 processors of a Cray T3D, respectively.

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Semantics Vs. Syntax Vs. Computations: Machine Models For Type-2 Polynomial-Time Bounded Functionals, James S. Royer Jan 1997

Semantics Vs. Syntax Vs. Computations: Machine Models For Type-2 Polynomial-Time Bounded Functionals, James S. Royer

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

This paper investigates analogs of the Kreisel-Lacombe-Shoenfield Theorem in the context of the type-2 basic feasible functionals. We develop a direct, polynomial-time analog of effective operation in which the time bounding on computations is modeled after Kapron and Cook's scheme for their basic polynomial-time functionals. We show that if P = NP, these polynomial-time effective operations are strictly more powerful on R (the class of recursive functions) than the basic feasible functions. We also consider a weaker notion of polynomial-time effective operation where the machines computing these functionals have access to the computations of their procedural parameter, but not to …

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Concurrent Simulation Of Plasma Reactors, Marc Rieffel, Stephen Taylor, Jerrell Watts, Sadasivan Shankar Jan 1997

Concurrent Simulation Of Plasma Reactors, Marc Rieffel, Stephen Taylor, Jerrell Watts, Sadasivan Shankar

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

This paper summarizes the computational techniques behind a novel concurrent simulation method used for studying the neutral flow inside plasma reactors. The technique is intended to cope with low pressure flow (less than 1.5 Torr) in realistic three-dimensional geometries. It is based on the Direct Simulation Monte Carlo method to accurately model rarefied gas flow. The concurrent formulation operates on a broad variety of shared-memory multiprocessors, multicomputers, and networked workstations.

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Practical Algorithms For Selection On Coarse-Grained Parallel Computers, Ibraheem Al-Furaih, Srinivas Aluru, Sanjay Goil, Sanjay Ranka Jan 1997

Practical Algorithms For Selection On Coarse-Grained Parallel Computers, Ibraheem Al-Furaih, Srinivas Aluru, Sanjay Goil, Sanjay Ranka

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

In this paper, we consider the problem of selection on coarse-grained distributed memory parallel computers. We discuss several deterministic and randomized algorithms for parallel selection. We also consider several algorithms for load balancing needed to keep a balanced distribution of data across processors during the execution of the selection algorithms. We have carried out detailed implementations of all the algorithms discussed on the CM-5 and report on the experimental results. We demonstrate that the randomized algorithms are superior to their deterministic counterparts.

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Integer Sorting Algorithms For Coarse-Grained Parallel Machines, Khaled Alsabti, Sanjay Ranka Jan 1997

Integer Sorting Algorithms For Coarse-Grained Parallel Machines, Khaled Alsabti, Sanjay Ranka

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

Integer sorting is a subclass of the sorting problem where the elements have integer values and the largest element is polynomially bounded in the number of elements to be sorted. It is useful for applications in which the size of the maximum value of element to be sorted is bounded. In this paper, we present a new distributed radix-sort algorithm for integer sorting. The structure of our algorithm is similar to radix sort except that it typically requires less number of communication phases. We present experimental results for our algorithm on two distributed memory multiprocessors, the Intel Paragon and the …

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Hpjava: Data Parallel Extensions To Java, Bryan Carpenter, Guansong Zhang, Geoffrey C. Fox, Xinying Li Jan 1997

Hpjava: Data Parallel Extensions To Java, Bryan Carpenter, Guansong Zhang, Geoffrey C. Fox, Xinying Li

Northeast Parallel Architecture Center

We outline an extension of Java for programming with distributed arrays. The basic programming style is Single Program Multiple Data (SPMD), but parallel arrays are provided as new language primitives. Further extensions include three distributed control constructs, the most important being a data-parallel loop construct. Communications involving distributed arrays are handled through a standard library of collective operations. Because the underlying programming model is SPMD programming, direct calls to MPI or other communication packages are also allowed in an HPJava program.

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A Comparison Of Annealing Techniques For Academic Course Scheduling, M.A. Saleh Elmohamed, Geoffrey C. Fox, Paul Coddington Jan 1997

A Comparison Of Annealing Techniques For Academic Course Scheduling, M.A. Saleh Elmohamed, Geoffrey C. Fox, Paul Coddington

Northeast Parallel Architecture Center

In this study we have tackled the NP-hard problem of academic class scheduling (or timetabling) at the university level. We have investigated a variety of approaches based on simulated annealing, including mean-field annealing, simulated annealing with three different cooling schedules, and the use of a rule-based preprocessor to provide a good initial solution for annealing. The best results were obtained using simulated annealing with adaptive cooling and reheating as a function of cost, and a rule-based preprocessor. This approach enabled us to obtain valid schedules for the timetabling problem for a large university, using a complex cost function that includes …

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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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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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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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Experiments With "Hp Java", Bryan Carpenter, Yuh-Jye Chang, Geoffrey C. Fox, Donald Leskiw Jan 1997

Experiments With "Hp Java", Bryan Carpenter, Yuh-Jye Chang, Geoffrey C. Fox, Donald Leskiw

Northeast Parallel Architecture Center

We consider the possible role of Java as a language for High Performance Computing. After discussing reasons why Java may be a natural candidate for a portable parallel programming language, we describe several case studies. These cover Java socket programming, message-passing through a Java interface to MPI, and class libraries for data-parallel programming in Java.

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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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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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The Software Architecture Of A Virtual Distributed Computing Environment, Haluk Topcuoglu, Salim Hariri, Wojtek Furmanski, Jon Valente Jan 1997

The Software Architecture Of A Virtual Distributed Computing Environment, Haluk Topcuoglu, Salim Hariri, Wojtek Furmanski, Jon Valente

Electrical Engineering and Computer Science - All Scholarship

The requirements of grand challenge problems and the deployment of gigabit networks makes the network computing framework an attractive and cost effective computing environment with which to interconnect geographically distributed processing and storage resources. Our project, Virtual Distributed Computing Environment (VDCE), provides a problem-solving environment for high-performance distributed computing over wide area networks. VDCE delivers well-defined library functions that relieve end-users of tedious task implementations and also support reusability. In this paper we present the conceptual design of VDCE software architecture, which is defined in three modules: a) the Application Editor, a user-friendly application development environment that generates the Application …

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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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Parallel Domain Decomposition And Load Balancing Using Space-Filling Curves, Srinivas Aluru, Faith E. Sevilgen Jan 1997

Parallel Domain Decomposition And Load Balancing Using Space-Filling Curves, Srinivas Aluru, Faith E. Sevilgen

Electrical Engineering and Computer Science - All Scholarship

Partitioning techniques based on space-filling curves have received much recent attention due to their low running time and good load balance characteristics. The basic idea underlying these methods is to order the multidimensional data according to a space-filling curve and partition the resulting one-dimensional order. However, space-filling curves are defined for points that lie on a uniform grid of a particular resolution. It is typically assumed that the coordinates of the points are representable using a fixed number of bits, and the run-times of the algorithms depend upon the number of bits used. In this paper, we present a simple …

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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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Selective Crossover: Towards Fitter Offspring, Chilukuri K. Mohan Jan 1997

Selective Crossover: Towards Fitter Offspring, Chilukuri K. Mohan

Electrical Engineering and Computer Science - All Scholarship

A new general-purpose crossover operator is proposed. The representation of a candidate solution is slightly perturbed, and the ensuing changes in fitness are calculated. Such fitness changes (for parents) are used in constructing the offspring resulting from crossover. Experiments with several sets of problems demonstrate that this approach leads to rapid increases in average and best fitness, and performs much better than traditional general-purpose crossover operators.

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A Global Computing Environment For Networked Resources, Haluk Topcuoglu, Salim Hariri Jan 1997

A Global Computing Environment For Networked Resources, Haluk Topcuoglu, Salim Hariri

Electrical Engineering and Computer Science - All Scholarship

Current advances in high-speed networks and WWW technologies have made network computing a cost-effective, high-performance computing alternative. New software tools are being developed to utilize efficiently the network computing environment. Our project, called Virtual Distributed Computing Environment (VDCE), is a high-performance computing environment that allows users to write and evaluate networked applications for different hardware and software configurations using a web interface. In this paper we present the software architecture of VDCE by emphasizing application development and specification, scheduling, and execution/runtime aspects.

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Simulated Annealing And Genetic Algorithms For Partial Shape Matching, Ender Ozcan, Chilukuri K. Mohan Jan 1997

Simulated Annealing And Genetic Algorithms For Partial Shape Matching, Ender Ozcan, Chilukuri K. Mohan

Electrical Engineering and Computer Science - All Scholarship

Partial shape matching may be viewed as an optimization problem, to be solved using methods such as simulated annealing (SA) and genetic algorithms (GAs). We apply and compare both these methods for matching input shapes with model shapes described in terms of features such as line segments and angles. The quality of matching is gauged using a measure derived from attributed shape grammars [10, 11]. Current results show that both SA and GA succeed in the shape matching task; the GA is faster and yields the global optimum more often than the versions of SA implemented.

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Standardization Of A Communication Middleware For High-Performance Real-Time Systems, Arkady Kanevsky, Anthony Skjellum, Jerrell Watts Jan 1997

Standardization Of A Communication Middleware For High-Performance Real-Time Systems, Arkady Kanevsky, Anthony Skjellum, Jerrell Watts

Electrical Engineering and Computer Science - All Scholarship

The last several years saw an emergence of standardization activities for real-time systems including standardization of operating systems (series of POSIX standards [1]), of communication for distributed (POSIX.21 [10]) and parallel systems (MPI/RT [5]) and real-time object management (realtime CORBA [9]). This article describes the ongoing standardization work and implementation of communication middleware for high performance real-time computing. The real-time message passing interface (MPI/RT) advances the non-real-time high-performance communication standard Message Passing Interface Standard (MPI), emphasizing changes that enable and support real-time communication, and is targeted for embedded, fault-tolerant and other real-time systems. MPI/RT is the only communication middleware layer …

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