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Global Grid (global + grid)

Distribution by Scientific Domains

Information Science and Computing	60%

Selected Abstracts

Neuroscience instrumentation and distributed analysis of brain activity data: a case for eScience on global Grids

CONCURRENCY AND COMPUTATION: PRACTICE & EXPERIENCE, Issue 15 2005
Rajkumar Buyya
Abstract The distribution of knowledge (by scientists) and data sources (advanced scientific instruments), and the need for large-scale computational resources for analyzing massive scientific data are two major problems commonly observed in scientific disciplines. Two popular scientific disciplines of this nature are brain science and high-energy physics. The analysis of brain-activity data gathered from the MEG (magnetoencephalography) instrument is an important research topic in medical science since it helps doctors in identifying symptoms of diseases. The data needs to be analyzed exhaustively to efficiently diagnose and analyze brain functions and requires access to large-scale computational resources. The potential platform for solving such resource intensive applications is the Grid. This paper presents the design and development of MEG data analysis system by leveraging Grid technologies, primarily Nimrod-G, Gridbus, and Globus. It describes the composition of the neuroscience (brain-activity analysis) application as parameter-sweep application and its on-demand deployment on global Grids for distributed execution. The results of economic-based scheduling of analysis jobs for three different optimizations scenarios on the world-wide Grid testbed resources are presented along with their graphical visualization. Copyright © 2005 John Wiley & Sons, Ltd. [source]

A Fast Simulation Method Using Overlapping Grids for Interactions between Smoke and Rigid Objects

COMPUTER GRAPHICS FORUM, Issue 2 2008
Yoshinori Dobashi
Abstract Recently, many techniques using computational fluid dynamics have been proposed for the simulation of natural phenomena such as smoke and fire. Traditionally, a single grid is used for computing the motion of fluids. When an object interacts with a fluid, the resolution of the grid must be sufficiently high because the shape of the object is represented by a shape sampled at the grid points. This increases the number of grid points that are required, and hence the computational cost is increased. To address this problem, we propose a method using multiple grids that overlap with each other. In addition to a large single grid (a global grid) that covers the whole of the simulation space, separate grids (local grids) are generated that surround each object. The resolution of a local grid is higher than that of the global grid. The local grids move according to the motion of the objects. Therefore, the process of resampling the shape of the object is unnecessary when the object moves. To accelerate the computation, appropriate resolutions are adaptively-determined for the local grids according to their distance from the viewpoint. Furthermore, since we use regular (orthogonal) lattices for the grids, the method is suitable for GPU implementation. This realizes the real-time simulation of interactions between objects and smoke. [source]

Ecological and evolutionary components of body size: geographic variation of venomous snakes at the global scale

BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 1 2009
LEVI CARINA TERRIBILE
Biogeographical patterns of animal body size and the environmental and evolutionary mechanisms that may be driving them have been broadly investigated in macroecology, although just barely in ectotherms. We separately studied two snake clades, Viperidae and Elapidae, and used phylogenetic eigenvector regression and ordinary least squares multiple regression methods to perform a global grid-based analysis of the extent at which the patterns of body size (measured for each species as its log10 -transformed maximum body length) of these groups are phylogenetically structured or driven by current environment trends. Phylogenetic relatedness explained 20% of the across-species size variation in Viperidae, and 59% of that of Elapidae, which is a more recent clade. Conversely, when we analysed spatial trends in mean body size values (calculated for each grid-cell as the average size of its extant species), an environmental model including temperature, precipitation, primary productivity (as indicated by the global vegetation index) and topography (range in elevation) explained 37.6% of the variation of Viperidae, but only 4.5% of that of Elapidae. These contrasted responses of body size patterns to current environment gradients are discussed, taking into consideration the dissimilar evolutionary histories of these closely-related groups. Additionally, the results obtained emphasize the importance of the need to start adopting deconstructive approaches in macroecology. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 98, 94,109. [source]

Exploratory Precipitation in North-Central China during the Past Four Centuries

ACTA GEOLOGICA SINICA (ENGLISH EDITION), Issue 1 2010
Liang YI
Abstract: Two robust precipitation reconstructions were conducted by combining tree-ring chronologies, dryness/wetness indices from historical documents, and climate data from the global grid. It was found that the recurrent drought history of a region can help us understand the variability of precipitation. Several dry/wet periods during the past four centuries and potential cycles of precipitation variation were determined. Furthermore, the reconstructions are not only consistent well with each other in North-central China, but also in good agreement with variations of precipitation in northeastern Mongolia, the Longxi area in Gangsu Province and the Dulan area of Qinghai Province, and the snow accumulation of the Guliya glacier. These synchronous variations indicate that it is valuable to study various climate records, find common information and determine the driving force of climate change. [source]