The total energy pseudopotential method is well suited to parallel processing. This paper discusses a procedure for calculating the valence electronic wavefunction in a given ionic configuration, and considers the exp...
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The total energy pseudopotential method is well suited to parallel processing. This paper discusses a procedure for calculating the valence electronic wavefunction in a given ionic configuration, and considers the exploitation of parallel processing using a data parallel approach. The implementation of this procedure on two message passing i860 based machines, containing up to 64 nodes, is described, and the prospects for massively parallel execution are examined.
Steady, two-dimensional, two-layer flow over an arbitrary topography is considered. The fluid in each layer is assumed to be inviscid and incompressible and flows irrotationally. The interfacial surface is found using...
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Steady, two-dimensional, two-layer flow over an arbitrary topography is considered. The fluid in each layer is assumed to be inviscid and incompressible and flows irrotationally. The interfacial surface is found using a boundary integral formulation, and the resulting integrodifferential equations are solved iteratively using Newton's method. A linear theory is presented for a given topography and the non-linear theory is compared against this to show how the non-linearity affects the problem.
The calculation of flows in pipe networks and in networks of mine shafts and the calculations of the currents in electrical circuits can be represented as variational problems. There are two approaches: the nodal meth...
The calculation of flows in pipe networks and in networks of mine shafts and the calculations of the currents in electrical circuits can be represented as variational problems. There are two approaches: the nodal method and the loop method. There is a variational representation for each of these. This paper describes the relationship between the two representations and in particular shows that the loop formulation is the Wolfe dual of the nodal formulation after the application of Legendre transformations to the variables and to the objective function.
Forma analysis is applied to the task of optimising the connectivity of a feed- forward neural network with a single layer of hidden units. This problem is reformulated as a multiset optimisation problem, and techniqu...
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parallelcomputing has provided the opportunity to perform high speed simulation. However, no guidelines exist for parallelizing discrete event simulation. This presents a barrier to the use of such techniques and the...
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parallelcomputing has provided the opportunity to perform high speed simulation. However, no guidelines exist for parallelizing discrete event simulation. This presents a barrier to the use of such techniques and the benefits of reduced simulation times. A methodology has therefore been developed to guide the novice in developing a parallel form of existing simulations. Using an illustrative example, this paper discusses the problems of parallelizing discrete event simulation and concludes with a summary of a methodology.< >
Modular application builders (MABs), such as AVS and Iris Explorer are increasingly being used in the visualization community. Such systems can already place compute intensive modules on supercomputers in order to uti...
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Modular application builders (MABs), such as AVS and Iris Explorer are increasingly being used in the visualization community. Such systems can already place compute intensive modules on supercomputers in order to utilize their power. This paper details two major projects at EPCC which attempted to fully integrate the MAB concept with a distributed memory MIMD (DM-MIMD) environment. The work presented was driven by two goals, efficient use of the resource and case of use by programmer and end user. We present a model of MABs and describe the major problems faced, giving solutions to them through two case studies.< >
Sequence similarity calculations of carbohydrates present several problems which must be addressed if a computer implementation is to be achieved. These problems range from the computational representation of the comp...
Waves at the interface of a two-layer fluid are considered. The fluid in the lower layer is incompressible with constant density and is flowing irrotationally. In the upper layer, the fluid is stationary but compressi...
Waves at the interface of a two-layer fluid are considered. The fluid in the lower layer is incompressible with constant density and is flowing irrotationally. In the upper layer, the fluid is stationary but compressible, and corresponds to an isothermal atmosphere with a density profile that decreases exponentially with height. The interface between the two fluids is assumed sharp. The formation of waves at the interface would come about typically as a result of the interaction of the moving lower layer of fluid with local topographical features, as with the classical problem of the generation of waves on the lee side of a mountain range. It is shown that the present model is capable of supporting the formation of interfacial waves that are similar in many respects to the classical gravity wave of Stokes, and that are ultimately limited in every case by the formation of a 120-degrees angle at the wave crest. The highly nonlinear wave profiles are computed numerically and compared with the predictions of linearized theory. An extended perturbation analysis is given near the point at which the inter-facial waves break down as a result of the Kelvin-Helmholtz instability.
A major difficulty in programming parallel computers is resolving the conflict between centralising data to ensure consistency and distributing data to ensure efficient access. Opportunistic combining networks can red...
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