Three parallel algorithms for classical molecular dynamics are presented. The first assigns each processor a fixed subset of atoms; the second assigns each a fixed subset of inter-atomic forces to compute; the third assigns each a fixed spatial region. The algorithms are suitable for molecular dynamics models which can be difficult to parallelize efficiently—those with short-range forces where the neighbors of each atom change rapidly. They can be implemented on any distributed-memory parallel machine which allows for message-passing of data between independently executing processors. The algorithms are tested on a standard Lennard-Jones benchmark problem for system sizes ranging from 500 to 100,000,000 atoms on several parallel supercomputers--the nCUBE 2, Intel iPSC/860 and Paragon, and Cray T3D. Comparing the results to the fastest reported vectorized Cray Y-MP and C90 algorithm shows that the current generation of parallel machines is competitive with conventional vector supercomputers even for small problems. For large problems, the spatial algorithm achieves parallel efficiencies of 90% and a 1840-node Intel Paragon performs up to 165 faster than a single Cray C9O processor. Trade-offs between the three algorithms and guidelines for adapting them to more complex molecular dynamics simulations are also discussed.

Fast parallel algorithms for short-range molecular dynamics

Let's read! We will often find out this sentence everywhere. When still being a kid, mom used to order us to always read, so did the teacher. Some books are fully read in a week and we need the obligation to support reading. What about now? Do you still love reading? Is reading only for you who have obligation? Absolutely not! We here offer you a new book enPDFd the perception of the visual world to read.

The Perception of the Visual World. By James J. Gibson. U.S.A.: Houghton Mifflin Company, 1950 (George Allen & Unwin, Ltd., London). Price 35s.

A Viking Lander 1 image was modeled as mixtures of reflectance spectra of palagonite dust, gray andesitelike rock, and a coarse rocklike soil. The rocks are covered to varying degrees by dust but otherwise appear unweathered. Rocklike soil occurs as lag deposits in deflation zones around stones and on top of a drift and as a layer in a trench dug by the lander. This soil probably is derived from the rocks by wind abrasion and/or spallation. Dust is the major component of the soil and covers most of the surface. The dust is unrelated spectrally to the rock but is equivalent to the global-scale dust observed telescopically. A new method was developed to model a multispectral image as mixtures of end-member spectra and to compare image spectra directly with laboratory reference spectra. The method for the first time uses shade and secondary illumination effects as spectral end-members; thus the effects of topography and illumination on all scales can be isolated or removed. The image was calibrated absolutely from the laboratory spectra, in close agreement with direct calibrations. The method has broad applications to interpreting multispectral images, including satellite images.

Spectral mixture modeling - A new analysis of rock and soil types at the Viking Lander 1 site. [on Mars]

Workflows and e-Science: An overview of workflow system features and capabilities

Multiagent Systems is the title of a collection of papers dedicated to surveying specific themes of Multiagent Systems (MAS) and Distributed Artificial Intelligence (DAI). All of them authored by leading researchers of this dynamic multidisciplinary field.

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Multiagent systems: a modern approach to distributed artificial intelligence

Various models and architectures for scheduling in grids may be found both in the literature and in practical applications. They differ in the number of scheduling components, their autonomy, general strategies, and the level of decentralization. The major aim of our research is to study impact of these differences on the overall performance of a Grid. To this end, in the paper we compare performance of two specific Grid models: one centralized and one distributed. We use GSSIM simulator to perform accurate empirical tests of algorithms. This paper is a starting point of an experimental study of centralized and decentralized approaches to Grid scheduling within the scope of the CoreGrid Resource Management and Scheduling Institute.

/pdf/comparison-of-centralized-and-decentralized-scheduling-49iwtd37om.pdf

Comparison Of Centralized And Decentralized Scheduling Algorithms Using GSSIM Simulation Environment

This paper presents recent work that has been performed in the context of high performance computing and hybrid architectures at Poznan Supercomputing and Networking Center. Three algorithms: JPEG2000 – compression/decompression, computational fluid mechanics and motion tracking have been parallelized on various architectures and compared to reference sequential applications. The performance results, implementation issues and best practices are discussed as well.

/pdf/high-performance-computing-on-new-accelerated-hardware-245tkaq36h.pdf

High Performance Computing on New Accelerated Hardware Architectures

A system for generating computer programs, the system comprising: a plurality of physical carriers of information (2) comprising thereon a description text (3) and/or a graphical symbol (4); an image capturing device (5) configured to capture a digital image; a computer device (6) configured to process the digital image and to recognize the carriers (2) on the image, determine the arrangement of the carriers (2) with respect to each other and to convert the extracted arrangement to a computer program; characterised in that the physical carriers of information (2) comprise thereon a rectangular contrasting marker (7) associated with an element of a computer program in the computer device (6).

A device for generating computer programs and a method for generating computer programs

In general resource management is often defined as a process of identifying application requirements, matching compute resources to jobs, allocating those resources, scheduling and monitoring them over time to run jobs as effi-ciently as possible. In case of urgent computing, additionally, in this process we have to deal with a set of specific event-driven or time-critical application requirements that must be satisfied by a resource provider to guarantee the immediate access to compute resources. There is no question that capabilities supporting urgent computing are re-quired in distributed high performance and high throughput computing infrastructures like Grids. Nevertheless, it is difficult to predict if and how urgent jobs will disturb scheduling policies as well as coexist with less critical waiting and running jobs submitted by other end-users. To date many approaches have been proposed to deal with urgent com-puting, for instance based on preemption or high job priorities and recently based on advance reservations. However, there is a lack of comprehensive analysis of the impact of urgent computing on existing schedulers and their effi-ciency. Moreover, many resource providers use a single evaluation criterion -utilization or average load of compute resources. In fact the utilization of compute resources as a metric is in contrast to other evaluation criteria relevant for urgent jobs, e.g. waiting time, response time, or mean fiow time. These additional criteria in our opinion can be treated as good metrics for urgent computing taking into account the end-users perspective rather than the resource provider centric view. As we demonstrate in this paper, the problem is not trivial and it requires workload analyses. Finally, in this paper we successfully used GSSIM simulator to run various experiments and benchmarks for different scheduling strategies where urgent jobs were additionally considered.

Impact of Urgent Computing on Resource Management Policies, Schedules and Resources Utilization

In a distributed multi-domain environment, where conditions of resources, services as well as applications change dynamically, we need reliable and scalable management capabilities. The quality of management depends on many factors among which distributed measurement and control primitives are particularly important. By exploiting the extensible monitoring infrastructure provided at the middleware level in a grid meta-scheduling service, in particular integration between GRMS (Grid Resource Management System) and Mercury (Grid Monitoring System), it is possible to perform analysis and then make intelligent use of grid resources. These provide the basis to realize dynamic and adaptive resource management strategies, as well as automatic checkpointing, opportunistic migration, rescheduling and policy-driven management, that has attracted attention of many researchers for the last few years. In this paper we present the current status of our ongoing research in this field together with an example of sensor oriented grid monitoring capabilities facilitating efficient remote control of applications and resources.

Krzysztof Kurowski

Papers

Comparison Of Centralized And Decentralized Scheduling Algorithms Using GSSIM Simulation Environment

High Performance Computing on New Accelerated Hardware Architectures

A device for generating computer programs and a method for generating computer programs

Impact of Urgent Computing on Resource Management Policies, Schedules and Resources Utilization

Sensor Oriented Grid Monitoring Infrastructures for Adaptive Multi-Criteria Resource Management Strategies