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parallel fractional cascading on hypercube multiprocessors

Computational Geometry: Theory and Applications 1992年第3期2卷 141-141页

作者： Dehne, F. Ferreira, A. Rau-Chaplin, A. Center for Parallel and Distributed Computing School of Computer Science Carleton University Ottawa Canada K1S 5B6 CNRS-Laboratoire de l'Informatique du Parallelisme Ecole Normale Superieure de Lyon 69364 Lyon cedex 07 France

Dehne, F., A. Ferreira and A. Rau-Chaplin, parallel fractional cascading on hypercube multiprocessors, Computational Geometry: Theory and Applications 2 (1992) 141–167. In this paper we present a new data-structuring technique for parallel computational geometry on a hypercube multiprocessor. This technique, called hypercube cascading, is an efficient parallel implementation of fractional cascading for the hypercube multiprocessor. That is, it allows complex data structures with catalogs to be traversed efficiently in parallel by a large number of simultaneous queries. We show that for monotone graphs with n nodes, m multiple look-up queries with path length at most p (including catalog look-ups) can be executed independently, in parallel, in time O( p log N + t s ( N )) on a hypercube multiprocessor of size N = max n, itm . The term t s ( N ) denotes the time for sorting N elements on a hypercube of size N ; currently t s ( N ) = O(log N log log N ). Note that, the best known sequential time complexity for one multiple look-up query, as presented by Chazelle and Guibas, is O( p + log N ). Our solution allows an arbitrary number of search queries to access the same node and its catalog at the same time. We present two parallel computational geometry applications of this technique: multiple stabbing of a simple polygonal path and multiple slanted range search.

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Automated modeling and analysis of agent-based simulations using the CASE framework

Automated modeling and analysis of agent-based simulations u...

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International Conference on Control, Automation, Robotics and Vision (ICARCV)

作者： James Decraene Malcolm Yoke Hean Low Fanchao Zeng Suiping Zhou Wentong Cai Parallel and Distributed Computing Center School of Computer Engineering Nanyang Technological University Singapore

We present a modular evolutionary framework, coined CASE for "complex adaptive system evolver", to automate the modeling and analysis of agent-based simulations (ABSs). The field of agent-based modeling is rapidly growing due to its capabilities to expose the emerging complex phenomena occurring in a wide range of natural and artificial systems such as biological cells, societies, battlefields, stock markets, etc. Nevertheless, studying agent-based simulations is a complicated, interdisciplinary and time-consuming process. Indeed, a large number of simulation parameters has to be considered to identify and fully understand the conditions leading to the emerging phenomena of interest. To tackle this difficulty, the study of ABSs is thus typically conducted in an iterative manner, where each iteration includes the successive and manual modeling of ABSs and analysis of simulation outcomes. To automate this iterative and time-consuming process, we propose CASE, a platform-independent framework capable of evolving ABSs to exhibit the desired emerging behaviors. Through this evolutionary approach, the examination, i.e., the modeling, execution and analysis, of ABSs is automated. This process automation significantly facilitates the examination of complex systems using ABSs. In this paper, we present in detail this modular evolutionary framework which is illustrated with an example experiment. In this experiment, CASE is utilized for Automated Red Teaming, a simulation-based vulnerability assessment technique commonly employed by defense analysts. The aim of this paper is to introduce this flexible computational framework which may potentially benefit related fields involving agent-based simulations such as the gaming or financial industries.

关键词： Computational modeling Adaptation model Computer aided software engineering Analytical models Evolutionary computation Biological system modeling Object oriented modeling

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Extended collective I/O for efficient retrieval of large objects

Extended collective I/O for efficient retrieval of large obj...

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International Conference on High Performance computing

作者： S. More A. Choudhary Center for Parallel and Distributed Computing Department of Electrical and Computer Engineering Northwestern University USA

Object-relational database management systems (OR-DBMS) extend the capabilities of the relational databases by allowing definition of new data types and methods to operate on these data types while retaining most of the relational model semantics. In this paper we examine issues related to parallel processing of queries in the object-relational model with respect to efficient storage and retrieval of large objects. We extend the concept of collective I/O and other related techniques such as request merging and data sieving in the database domain to achieve high performance in the retrieval of large objects. We deal with the I/O optimization problem in the query executor, access methods and the low level runtime system. We also propose a new technique called pooled striping for efficient storage of large objects on multiple disks. The results presented in this paper clearly show the effectiveness of the proposed I/O optimization techniques in handling large amounts of data in a parallel object-relational database system.

关键词： Electrical capacitance tomography parallel processing Concurrent computing Relational databases Database systems Information retrieval Merging Ear Data handling distributed computing

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Consistency Aware Dead Reckoning Threshold Tuning with Server Assistance in Client-Server-Based DVEs

Consistency Aware Dead Reckoning Threshold Tuning with Serve...

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International Conference on Computer and Information Technology (CIT)

作者： Yusen Li Wentong Cai Parallel and Distributed Computing Center School of Computer Engineering Nanyang Technological University Singapore

In distributed virtual environments (DVEs), maintaining a consistent view of the virtual world among all users is a primary task. Due to the resource limitations such as network capacity and computational power, the consistency of the virtual world cannot be guaranteed sometimes. In this paper, we try to address this problem in client-server-based DVEs by considering server side network capacity limitation. We look at the position update packets from client to server and show the impact of packet loss due to server side network capacity limitation on the consistency of the virtual world. We assume clients use Dead Reckoning (DR) models to control position updates. In order to adapt client updates with the server side network capacity to avoid update packet loss, two server assistant DR threshold tuning policies for different updating schemas are proposed in this paper. The proposed tuning polices are validated to have good performance by simulation results.

关键词： Servers Avatars Tuning Predictive models Measurement Dead reckoning Bandwidth

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A Service Oriented HLA RTI on the Grid

A Service Oriented HLA RTI on the Grid

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IEEE International Conference on Web Services (ICWS)

作者： Ke Pan Stephen John Turner Wentong Cai Zengxiang Li Parallel and Distributed Computing Center School of Computer Engineering Nanyang Technological University Singapore

Modeling and simulation permeate all areas of business, science and engineering. To promote the interoperability and reusability of simulation applications and link geographically dispersed simulation components, distributed simulation was introduced. While the high level architecture (HLA) is the IEEE standard for distributed simulation, a run time infrastructure (RTI) provides the actual implementation of the HLA. With increased size and complexity of simulation applications, large amounts of distributed computational and data resources are required. The Grid provides a flexible, secure and coordinated resource sharing environment which can facilitate distributed simulation execution. In this paper, we propose a service oriented HLA RTI (SOHR) framework which provides the functionalities of an RTI as Grid services and enables large scale distributed simulations to be conducted on a heterogeneous Grid environment. The various services in SOHR can be dynamically deployed, discovered and undeployed, leading to a scalable distributed simulation environment. While the communications between simulators are through Grid service invocations, the standard HLA interface is provided as a library to increase simulator reusability and interoperability. A subset of HLA specifications was implemented in a SOHR prototype based on GT4 and the experimental results have verified the feasibility of SOHR.

关键词： Computational modeling Resource management distributed computing Computer simulation Web services Grid computing Application software Computer architecture Middleware Wide area networks

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Implementation of Data Distribution Management services in a Service Oriented HLA RTI 09

Implementation of Data Distribution Management services in a...

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Simulation Winter Conference

作者： Ke Pan Stephen John Turner Wentong Cai Zengxiang Li Parallel and Distributed Computing Center School of Computer Engineering Nanyang Technological University Singapore

ISBN: (纸本)9781424457717

Simulation is a low cost and safe alternative to solve complex problems in various areas. To promote reuse and interoperability of simulation applications and link geographically dispersed simulation components, distributed simulation was introduced. The High Level Architecture (HLA) is the IEEE standard for distributed simulation. The actual implementation of the HLA standard is provided by a Run Time Infrastructure (RTI). The HLA defines six service groups. Its Data Distribution Management (DDM) service group aims at optimizing communication efficiency between simulation components and there are various approaches for DDM implementation. We have previously developed a Service Oriented HLA RTI (SOHR) which enables distributed simulations to be conducted across administrated domains on the Grid. It maps the six HLA service groups into different management services and creates a plug-and-play paradigm for an HLA RTI implementation so that different approaches for a service group can be easily implemented into SOHR. To demonstrate the plug-and-play paradigm, this paper discusses the implementation of two DDM approaches, the grid-based approach and an extended efficient sort-based approach, in SOHR. Experiments have also been carried out to compare their performance in different scenarios.

关键词： distributed decision making Computational modeling Routing Subscriptions distributed computing Costs Technology management Engineering management Concurrent computing Data engineering

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A hybrid Interest Management mechanism for peer-to-peer Networked Virtual Environments

A hybrid Interest Management mechanism for peer-to-peer Netw...

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International Symposium on parallel and distributed Processing (IPDPS)

作者： Ke Pan Wentong Cai Xueyan Tang Suiping Zhou Stephen John Turner Parallel and Distributed Computing Center School of Computer Engineering Nanyang Technological University Singapore

An Interest Management (IM) mechanism eliminates irrelevant status updates transmitted in Networked Virtual Environments (NVE). However, IM itself involves both computation and communication overhead, of which the latter is the focus of this paper. Traditionally, there are area-based and cell-based IM mechanisms. This paper proposes a hybrid IM mechanism for peer-to-peer NVEs, that utilizes the cell-based mechanism to reduce Area-Of-Interest (AOI) updates in the area-based mechanism so as to reduce its communication overhead. To compare the new mechanism with the two traditional approaches, a multiplayer game scenario is simulated. The performance results show that, compared to the traditional mechanisms, the hybrid mechanism reduces the upload bandwidth consumption by more than 25.28 percent, reduces the overhead ratio from more than 67.54 percent to only 25.17 percent, and allows more than 5000 players in the Internet to join the same game with today's network upload bandwidth.

关键词： Environmental management Peer to peer computing Virtual environment Delay Computer architecture Bandwidth Costs Computer network management Technology management Engineering management

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Bounds on performance of VLSI processor arrays

Bounds on performance of VLSI processor arrays

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International Symposium on parallel Processing

作者： A. Nayak N. Santoro Center for Parallel & Distributed Computing School of Computer Science Carleton University Ottawa ONT Canada

This paper discusses the effect of processor failures on computation performed on two-dimensional VLSI processor arrays. Previously established properties of catastrophic fault patterns are used to study inherent limits to reconfigurability of these regular architectures. Bounds on number of faults the system can tolerate to provide guaranteed performance are derived. These results are the generalization of the results obtained in the case of one-dimensional processor arrays.< >

关键词： Very large scale integration Circuit faults Systolic arrays distributed computing Computer architecture Fault tolerant systems Fault tolerance Fault detection Joining processes Computer science

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Evolving agent-based simulations in the clouds

Evolving agent-based simulations in the clouds

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International Workshop on Advanced Computational Intelligence (IWACI)

作者： James Decraene Yong Yong Cheng Malcolm Yoke Hean Low Suiping Zhou Wentong Cai Chwee Seng Choo Parallel and Distributed Computing Center Nanyang Technological University Singapore DSO National Laboratories Singapore

Evolving agent-based simulations enables one to automate the difficult iterative process of modeling complex adaptive systems to exhibit pre-specified/desired behaviors. Nevertheless this emerging technology, combining research advances in agent-based modeling/simulation and evolutionary computation, requires significant computing resources (i.e., high performance computing facilities) to evaluate simulation models across a large search space. Moreover, such experiments are typically conducted in an infrequent fashion and may occur when the computing facilities are not fully available. The user may thus be confronted with a computing budget limiting the use of these “evolvable simulation” techniques. We propose the use of the cloud computing paradigm to address these budget and flexibility issues. To assist this research, we utilize a modular evolutionary framework coined CASE (for complex adaptive system evolver) which is capable of evolving agent-based models using nature-inspired search algorithms. In this paper, we present an adaptation of this framework which supports the cloud computing paradigm. An example evolutionary experiment, which examines a simplified military scenario modeled with the agent-based simulation platform MANA, is presented. This experiment refers to Automated Red Teaming: a vulnerability assessment tool employed by defense analysts to study combat operations (which are regarded here as complex adaptive systems). The experimental results suggest promising research potential in exploiting the cloud computing paradigm to support computing intensive evolvable simulation experiments. Finally, we discuss an additional extension to our cloud computing compliant CASE in which we propose to incorporate a distributed evolutionary approach, e.g., the island-based model to further optimize the evolutionary search.

关键词： Computational modeling Adaptation model Brain modeling

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Adaptive data consistency management in collaborative editing environment

Adaptive data consistency management in collaborative editin...

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International Conference on Information and Communication Technologies: From Theory to Applications, ICTTA

作者： M.A. Omar F. Haron R. Abdullah Parallel and Distributed Computing Center School of Computer Science Universiti Sains Malaysia Penang Malaysia

Collaborative editing is a subset of groupware system. Groupware or computer supported cooperative work (CSCW) application is "a computer-based system that supports groups of people engaged in a common task (or goal) and that provide an interface to a shared environment". This research area is also known as collaborative computing. Collaborative environment enables computer-based collaboration in wide-area network, static and dynamic resource sharing and instant or delayed feedback from collaborators. The objective of a collaborative environment is to allow coherent and consistent object sharing and manipulation by distributed users. Some examples of collaborative activities include desktop conferencing, cooperative document editing, cooperative designing and modeling. Consistency management mechanisms are needed to resolve conflicting actions performed by multiple users. Conflicting actions include simultaneous modification of shared data and out-of-order of data arrival and data execution due to communication delay.

关键词： Environmental management Collaboration Collaborative work Collaborative software Computer interfaces Application software Computer applications Computer networks Resource management Feedback

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