Gravity Pipe

Gravity Pipe

Gravity Pipe, otherwise known as GRAPE, is a project which uses hardware acceleration to perform gravitational computations. Integrated with Beowulf-style commodity computers, the GRAPE system calculates the force of gravity that a given mass, such as a star, exerts on others. [http://grape.astron.s.u-tokyo.ac.jp/grape/news/ABC/ABC-cuttingedge000602.html ABCNEWS.com : Cutting Edge: The GRAPE-6 Supercomputer ] ] The project resides at Tokyo University.

Nomenclature

The acronym GRAPE derives from "GRAvity PipE", the capitalization used by the authors of the system on their websites. The GRAPE hardware acceleration component "pipes" the force computation to the general-purpose computer serving as a node in a parallelized cluster as the innermost loop of the gravitational model.

Its shortened name, GRAPE, was chosen as an intentional reference to the Apple Inc. line of computers.

Method

The primary calculation in GRAPE hardware is a summation of the forces between a particular star and every other star in the simulation. Several versions (GRAPE-1, GRAPE-3 and GRAPE-5) use the Logarithmic Number System (LNS) in the pipeline to calculate the approximate force between two stars, and take the antilogarithms of the x, y and z components before adding them to their corresponding total. [ J Makino and M. Taiji, "Scientific Simulations with Special Purpose Computers: The GRAPE Systems", Wiley. 1998. ] The GRAPE-2, GRAPE-4 and GRAPE-6 use floating point arithmetic for more accurate calculation of such forces. The advantage of the logarithmic-arithmetic versions is they allow more and faster parallel pipes for a given hardware cost because all but the sum portion of the GRAPE algorithm (1.5 power of the sum of the squares of the input data divided by the input data) is easy to perform with LNS.

Application

GRAPE computes approximate solutions to the historically intractable n-body problem, which is of interest in astrophysics and celestial mechanics. "n" refers to the number of celestial bodies in a given problem. While the 2-body problem was solved by Kepler's Laws in the 17th century, any calculation where n > 2 has historically been a nigh-impossible challenge for the minds of man. An analytical solution exists for n = 3 although the resulting series converges too slowly to be of practical use. For n > 2 solutions are generally calculated numerically by determining the interaction between all particles. Thus, the calculation scales as n².

GRAPE assists in calculations of interactions between particles where the interaction scales as x-2. This dependence is hardwired, drastically improving calculation times. These problems include the evolution of galaxies (gravitation force scales as r-2). Similar problems exist in molecular chemistry and biology, where the force considered would be electrical rather than gravitational.

Prizes

The LNS-based GRAPE-3 architecture won the Price Performance category of the Gordon Bell Prize in 1999, at about $7 per MegaFLOPS. This category measures the price efficiency of a particular machine in terms of the price in dollars per megaFLOPS. The particular implemenation "Grape-6" also won prizes in 2000 and 2001 (see external links).

See also

*The Gordon Bell Prize, named in honor of Gordon Bell, is administered by the Association for Computing Machinery.
*Supercomputer and High-performance computing are main articles on the general subject.

Notes

External links

* [http://grape.astron.s.u-tokyo.ac.jp/grape/ The GRAPE site at the University of Tokyo]
* [http://www.sc2000.org/bell/pastawrd.htm Gordon Bell prize history]
* [http://www.top500.org The Top 500 List]
* [http://grape.astron.s.u-tokyo.ac.jp/~makino/grape6.html The GRAPE-6 Implementation]


Wikimedia Foundation. 2010.

Игры ⚽ Поможем сделать НИР

Look at other dictionaries:

  • Pipe Networks — generally refers to a common problem in Hydraulic Design. In order to direct water to many individuals in a municipal water supply, many times the water is routed through a Water supply network. A major part of this network may consist of… …   Wikipedia

  • Gravity separation — is an industrial method of separating two components from a suspension or any other homogeneous mixture where separating the components with gravity is sufficiently practical. All of the gravitational methods are common in the sense that they all …   Wikipedia

  • Pipe (fluid conveyance) — For structural pipe, see Hollow structural section. For other uses, see Pipe (disambiguation). Steel pipes …   Wikipedia

  • Pipe (material) — A pipe is a tube or hollow cylinder used to convey materials or as a structural component. The terms pipe and tube are almost interchangeable. A pipe is generally specified by the internal diameter (ID) whereas a tube is usually defined by the… …   Wikipedia

  • Heat pipe — A heat pipe is a heat transfer mechanism that can transport large quantities of heat with a very small difference in temperature between the hotter and colder interfaces. Inside a heat pipe, at the hot interface a fluid turns to vapour and the… …   Wikipedia

  • Loop heat pipe — A loop heat pipe (LHP) is a two phase heat transfer device that uses capillary action to remove heat from a source and passively move it to a condenser or radiator. LHPs are similar to heat pipes but have the advantage of being able provide… …   Wikipedia

  • Half-pipe — A half pipe is a structure used in gravity extreme sports such as snowboarding, skateboarding, skiing, freestyle BMX and inline skating. The structure is usually wood, although sometimes the surface is made of another material such as concrete,… …   Wikipedia

  • Vitrified clay pipe — (VCP) is pipe made from clay that has been subjected to vitrification, a process which fuses the clay particles to a very hard, inert, glass like state. VCP is commonly used in sewer gravity collection mains because of its reasonable price and… …   Wikipedia

  • Steam-Assisted Gravity Drainage - SAGD — Steam assisted gravity drainage (SAGD) is a drilling technique that is used to extract heavy oil that is too deep or otherwise economically inefficient to mine using traditional methods. The process was originally developed by the Alberta, Canada …   Investment dictionary

  • Feed pipe — Feed Feed, n. 1. That which is eaten; esp., food for beasts; fodder; pasture; hay; grain, ground or whole; as, the best feed for sheep. [1913 Webster] 2. A grazing or pasture ground. Shak. [1913 Webster] 3. An allowance of provender given to a… …   The Collaborative International Dictionary of English

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”