In this paper,a coupling strategy of the Parareal algorithm with the Waveform Relaxation method is presented for the parallel solution of differential algebraic *** classical Waveform Relaxation(in space) method and t...
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In this paper,a coupling strategy of the Parareal algorithm with the Waveform Relaxation method is presented for the parallel solution of differential algebraic *** classical Waveform Relaxation(in space) method and the Parareal(in time) method are first recalled,followed by the introduction of a coupled Parareal-Waveform Relaxation method recently introduced for the solution of partial differential ***,this coupled method is extended to the solution of differential algebraic *** experiments,performed on parallel multicores architectures,illustrate the impressive performances of this new method.
Contentions can degrade the performance of communication significantly on network topology like 3D-Mesh/Torus. On these topologies, it is important to establish a method for predicting penalty of contentions to en...
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Contentions can degrade the performance of communication significantly on network topology like 3D-Mesh/Torus. On these topologies, it is important to establish a method for predicting penalty of contentions to enable precise and fast tuning on communications. For example, techniques of tuning such as choosing dynamically faster algorithm of collective communications or finding appropriate task-allocation depends on the preciseness of the performance prediction. This research proposes a method for predicting a penalty of contentions by using detailed analysis of packet priority on direct interconnection network. Usually, the penalty of contentions is predicted by counting the number of communications issued on the same link at the same time. However, the actual amount of delay caused by contentions depends on the way of arbitrating messages. The message is divided into the packets and transmitted. Then, the contentions between those packets are arbitrated by applying the priority to each packet Therefore, when the contentions occur, the message which has a lower priority is blocked. By considering these priorities, the method proposed in this research becomes to predict the penalty of contentions more accurately and faster. In the evaluation experiment, the penalty of contentions predicted without considering packet priority is the twice or more than it predicted by simulation. On the other hand, the proposed method of predicting the penalty of contentions is predictable in the accuracy within 20% against simulation. Moreover, the prediction by proposed method is possible to execute it enough at short time.
We explore novel algorithms for DVS (Dynamic Voltage Scaling) based energy minimization of DAG (Directed Acyclic Graph) based applications on parallel and distributed machines in dynamic environments. Static DVS algor...
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We explore novel algorithms for DVS (Dynamic Voltage Scaling) based energy minimization of DAG (Directed Acyclic Graph) based applications on parallel and distributed machines in dynamic environments. Static DVS algorithms for DAG execution use the estimated execution time. The estimated time in practice is overestimated or underestimated. Therefore, many tasks may be completed earlier or later than expected during the actual execution. For overestimation, the extra available slack can be added to future tasks so that energy requirements can be reduced. For underestimation, the increased time may cause the application to miss the deadline. Slack can be reduced for future tasks to reduce the possibility of not missing the deadline. In this paper, we present novel dynamic scheduling algorithms for reallocating the slack for future tasks to reduce energy and/or satisfy deadline constraints. Experimental results show that our algorithms are comparable to static algorithms applied at runtime in terms of energy minimization and deadline satisfaction, but require considerably smaller computational overhead. (C) 2010 Elsevier Inc. All rights reserved.
The problem of indexing and retrieval of medical of images in computer networks is considered. The technique and technology of organization of distributed search of images, using Grid resources, is described. The data...
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The problem of indexing and retrieval of medical of images in computer networks is considered. The technique and technology of organization of distributed search of images, using Grid resources, is described. The data of numerical experiments on the example of a database of images in a network with 15 computing nodes, are given.
A parallel query processing method is proposed for the design and construction of web search engines to efficiently deal with dynamic variations in query traffic. The method allows for the efficient use of different d...
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A parallel query processing method is proposed for the design and construction of web search engines to efficiently deal with dynamic variations in query traffic. The method allows for the efficient use of different distributed indexing and query processing strategies in server clusters consisting of multiple computational/storage nodes. It also enables a better utilization of local and distributed hardware resources as it automatically re-organizes parallel computations to benefit from the advantages of two mixed modes of operation, namely: a newly proposed synchronous mode and the standard asynchronous computing mode. Switching between modes is facilitated by a round-robin strategy devised to grant each query a fair share of the hardware resources and properly predict query throughput. Performance is evaluated by experimental methods and two case studies serve to show how to develop efficient parallel query processing algorithms for large-scale search engines based on the proposed paradigm. (C) 2010 Elsevier B.V. All rights reserved.
Energy consumption is a critical issue in parallel and distributed embedded systems. We present a novel algorithm for energy efficient scheduling of Directed Acyclic Graph (DAG) based applications on Dynamic Voltage S...
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Energy consumption is a critical issue in parallel and distributed embedded systems. We present a novel algorithm for energy efficient scheduling of Directed Acyclic Graph (DAG) based applications on Dynamic Voltage Scaling (DVS) enabled systems. Experimental results show that our algorithm provides near optimal solutions for energy minimization with considerably smaller computational time and memory requirements compared to an existing algorithm that provides near optimal solutions. (C) 2009 Elsevier Inc. All rights reserved.
An all-to-all communication algorithm is said to be optimal if it has the smallest communication delay. Previous all-to-all personalized exchange algorithms are mainly for hypercube, mesh, and torus. In Yang and Wang ...
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An all-to-all communication algorithm is said to be optimal if it has the smallest communication delay. Previous all-to-all personalized exchange algorithms are mainly for hypercube, mesh, and torus. In Yang and Wang (2000) [13], Yang and Wang proved that a multistage interconnection network (MIN) is a better choice for implementing all-to-all personalized exchange and they proposed optimal all-to-all personalized exchange algorithms for MINs. In Massini (2003)[9], Massini proposed a new optimal algorithm for MINs, which is independent of the network topology. Do notice that the algorithms in [9] and [13] work only for MINs with the unique path property (meaning that there is a unique path between each pair of source and destination) and satisfying N = 2(n), in which N is the number of processors, 2 means all the switches are of size 2 x 2, and n is the number of stages. In Padmanabhan (1991) [10], Padmanabhan proposed the generalized shuffle-exchange network (GSEN), which is a generalization of the shuffle-exchange network. Since a GSEN does not have the unique path property, the algorithms in [9] and [13] cannot be used. The purpose of this paper is to consider the all-to-all personalized exchange problem in GSENs. An optimal algorithm and several bounds will be proposed. (C) 2010 Published by Elsevier B.V.
The fact that loosely bonded DNA bases could tolerate large structural fluctuations, form a dissipative environment for a charge traveling through the DNA. Nonlinear stochastic nature of structural fluctuations facili...
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The fact that loosely bonded DNA bases could tolerate large structural fluctuations, form a dissipative environment for a charge traveling through the DNA. Nonlinear stochastic nature of structural fluctuations facilitates rich charge dynamics in DNA. We study the complex charge dynamics by solving a nonlinear, stochastic, coupled system of differential equations. Charge transfer between donor and acceptor in DNA occurs via different mechanisms depending on the distance between donor and acceptor. It changes from tunneling regime to a polaron assisted hopping regime depending on the donor-acceptor separation. Also we found that charge transport strongly depends on the feasibility of polaron formation. Hence it has complex dependence on temperature and charge-vibrations coupling strength. Mismatched base pairs, such as different conformations of the G·A mispair, cause only minor structural changes in the host DNA molecule, thereby making mispair recognition an arduous task. Electron transport in DNA that depends strongly on the hopping transfer integrals between the nearest base pairs, which in turn are affected by the presence of a mispair, might be an attractive approach in this regard. I report here on our investigations, via the I-V characteristics, of the effect of a mispair on the electrical properties of homogeneous and generic DNA molecules. The I-V characteristics of DNA were studied numerically within the double-stranded tight-binding model. The parameters of the tight-binding model, such as the transfer integrals and on-site energies, are determined from first-principles calculations. The changes in electrical current through the DNA chain due to the presence of a mispair depend on the conformation of the G·A mispair and are appreciable for DNA consisting of up to 90 base pairs. For homogeneous DNA sequences the current through DNA is suppressed and the strongest suppression is realized for the G(anti)·A(syn) conformation of the G·A mispair. For inhomogene
This paper proposes a method for reducing the number of search nodes involved in the solution of queries arriving to a Web search engine. The method is applied by the query receptionist machine during situations of su...
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This paper proposes a method for reducing the number of search nodes involved in the solution of queries arriving to a Web search engine. The method is applied by the query receptionist machine during situations of sudden peaks in query traffic to reduce the load on the search nodes. The experimental evaluation based on actual traces from users of a major search engine, shows that the proposed method outperforms alternative strategies. This is more evident for systems composed of a large number of search nodes which indicates that the method is also more scalable than the alternative strategies. (C) 2010 Published by Elsevier Ltd.
This report is devoted to discussion of numerical and symbolic computing ratio in beam physics. We tray to draw attention on basic conceptual and computational problems first of all. It is known that the main problem ...
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This report is devoted to discussion of numerical and symbolic computing ratio in beam physics. We tray to draw attention on basic conceptual and computational problems first of all. It is known that the main problem in modern computational beam physics connected with high performance computing realization. The most of used approaches are not appropriate for computing using multiprocessing systems. Here we give some possible solutions, which based on a matrix presentation of necessary information and modern information technologies. (C) 2010 Published by Elsevier Ltd.
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