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The gyrofluid electromagnetic (GEM) model studies the phenomena in the context of edge turbulence, a matter of adding collisions and electromagnetic induction to the parallel dynamics of the standard six-moment toroidal model, the use of which was done in core turbulence works. Currently, the code describes the fluctuation free-energy conservation in a gyrofluid model by means of the polarization...
gLite is one of the largest distributed computing infrastructures in operation. It provides access to hundreds of different clusters - all installed and maintained in different ways. This paper analyses the difficulties which users typically experience when moving from their own workstation via clusters or supercomputers to the grid. Based on that analysis, this paper presents tools, which helps to...
The Integrated Tokamak Modelling Task Force (ITM-TF) is developing an infrastructure where the validation needs, as being formulated in terms of multi-device data access and detailed physics comparisons aiming for inclusion of synthetic diagnostics in the simulation chain, are key components. A device independent approach to data transport and a standardized approach to data management (data structures,...
Scheduling large amounts of tasks in distributed computing platforms composed of millions of nodes is a challenging goal, even more in a fully decentralized way and with low overhead. Thus, we propose a new scalable scheduler for task workflows with deadlines following a completely decentralized architecture. It's built upon a tree-based P2P overlay that supports efficient and fast aggregation of...
In the technique known as network coordinates, the network latency between nodes is modeled as the distance between points in a metric space. Actual network latencies, however, exhibit numerous triangle inequality violations, which result in significant error between the actual latency and the distance as determined by the network coordinates. In this work, we show how graph clustering techniques...
Artificial Bee Colony (ABC) algorithm is an optimisation algorithm based on the intelligent behaviour of honey bee swarm. In this work, ABC algorithm is used to optimise the equilibrium of confined plasma in a nuclear fusion device. Plasma physics research for fusion still presents open problems that need a large computing capacity to be solved. This optimisation process is a long time consuming process...
Desktop Grids harvest the computing power of idle desktop computers whether these are volunteer or deployed at an institution. Allowing foreign applications to run on these resources requires the sender of the application to be trusted, but trust in goodwill is never enough. An efficient solution is to provide a secure isolated execution environment ("sandbox"), which does not constrain...
The commercial success of Cloud computing and recent developments in Grid computing have brought platform virtualization technology into the field of high performance computing. Virtualization offers both more flexibility and security through custom user images and user isolation. In this paper, we deal with the problem of distributing virtual machine (VM) images to a set of distributed compute nodes...
Virtualization technologies have recently gained a lot of interest in Grid computing as they allow flexible resource management. However, the most common way to exploit grids relies on dedicated services like resource management systems (RMSs) to get resources at a particular time. To improve resource usage, most of these systems provide a best-effort mode where lowest priority jobs can be executed...
Pervasive Grid Computing Platforms include centralized computing nodes (e. g. parallel servers) as well as decentralized and mobile devices. Pervasive Grid applications include data- and computing-intensive components which can be mapped also onto decentralized and mobile nodes. The effective and practical success of this mapping resides also in deriving proper configurations of applications which...
Calculating neoclassical (NC) transport is a fundamental part of the complete simulation cycle of the behavior of plasmas inside all tokamaks and stellerators. Also, due to NC transport is mainly determined by the magnetic properties of the device, its study is mandatory to ensure the efficiency of a certain coil configuration before it is implemented in a Fusion reactor. Thus, improvements to already...
Facing computing and data intensive problems scientists are forced to use all the available resources to solve their problems. This applies to the usage of different distributed e-Infrastructures based on different concepts and architectures. Providing the end user with easy access to such complex systems is a very challenging task and refers to the issues related to the interoperability and interoperation...
FAFNER is code developed by Lister which simulates by Monte Carlo methods the Neutral Beam Injection (NBI) technology, one of the most extended heating methods for fusion devices. To the date, FAFNER has been usually run at CIEMAT adapted to the TJ-II helical axis stellarator on shared memory Cray architecture machines. From this version, FAFNER has been ported to the Grid in the framework of the...
A fundamental problem in large scale Grids is the need for efficient and scalable techniques for resource discovery and scheduling. In traditional resource scheduling systems a single scheduler handles information about all computing resources and schedules jobs. This centralized approach has a serious scalability problem, since it introduces a bottleneck, as well as a single point of failure. Some...
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