Multiphysics coupling presents a significant challenge in terms of both computational accuracy and performance. Achieving high performance on coupled simulations can be particularly challenging in a high-performance c...
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Multiphysics coupling presents a significant challenge in terms of both computational accuracy and performance. Achieving high performance on coupled simulations can be particularly challenging in a high-performance computing context. The US Department of Energy Exascale Computing Project has the mission to prepare mission-relevant applications for the delivery of the exascale computers starting in 2023. Many of these applications require multiphysics coupling, and the implementations must be performant on exascale hardware. In this special issue we feature six articles performing advanced multiphysics coupling that span the computational science domains in the Exascale Computing Project.
One question before the high-performance computing community is "How will application developers write code for exascale machines?" At this point it looks like they might be riding a rough beast indeed. This...
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One question before the high-performance computing community is "How will application developers write code for exascale machines?" At this point it looks like they might be riding a rough beast indeed. This paper is a brief assessment of where we stand now with respect to writing programs for our largest supercomputers and what we should do next. MPI is likely to remain a critical part of the programming infrastructure as we move towards exascale, but more is needed, in particular a robust, portable, and effective standard for parallel programming within a single address space, perhaps for heterogeneous processors. Formal methods provide the only truly scalable approach to developing correct code in this complex programming environment.
Farmers' attitudes to risk are viewed within a focus-loss framework. Sets of indifference curves are constructed for five farmers who are willing to forgo expected income for increases in a probabilisticly defined...
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Farmers' attitudes to risk are viewed within a focus-loss framework. Sets of indifference curves are constructed for five farmers who are willing to forgo expected income for increases in a probabilisticly defined minimum income. Each set of curves is compared with the respective farmer's utility function as derived by the modified yon Neumann-Morgenstern method. [ABSTRACT FROM AUTHOR]
A preference order dynamic programming model proposed in the literature for solving stochastic knapsack problems is shown to be somewhat limited from both the methodological and computational points of view. A counter...
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A preference order dynamic programming model proposed in the literature for solving stochastic knapsack problems is shown to be somewhat limited from both the methodological and computational points of view. A counterexample is presented contradicting the optimality of a procedure designed for normal variates.
The selection of capital projects in a production environment is complicated by the existence of multiple and conflicting goals. Typical production objectives for cost minimization often conflict with goals for qualit...
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The selection of capital projects in a production environment is complicated by the existence of multiple and conflicting goals. Typical production objectives for cost minimization often conflict with goals for quality, environmental standards, labor relations, etc. This problem of project selection is further complicated by the uncertainty inherent in product demand, the key factor in production management. This paper approaches these complications by employing an integer goal programming (to compensate for multiple conflicting objectives) with chance-constrained capabilities (to reflect uncertainty in product demand). The approach is demonstrated via an in-depth case example of a production problem.
A chance-constrained formulation is presented for a zero-one goal programming problem whose coefficients in the technological matrix are stochastic. The model is presented with a numerical example. A capital budgeting...
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A chance-constrained formulation is presented for a zero-one goal programming problem whose coefficients in the technological matrix are stochastic. The model is presented with a numerical example. A capital budgeting problem is taken for illustration.
In this paper, we develop conditions for the Takayama-Judge spatial equilibrium model to collapse into the classical Cournot model. In the case of heterogeneous demand and cost functions, the linear complementarity pr...
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In this paper, we develop conditions for the Takayama-Judge spatial equilibrium model to collapse into the classical Cournot model. In the case of heterogeneous demand and cost functions, the linear complementarity programming formulation is proposed to model the spatial Cournot model. Lastly, we implement the spatial equilibrium Cournot model to the US coal market and compare its performance to that of the original Takayama-Judge model. To the best of our knowledge, this is the only spatial equilibrium Cournot model estimated and implemented. (C) 2002 Elsevier Science B.V. All rights reserved.
There is a need for predictive and aggregate output response models suitable for answering questions about short-term changes in agricultural output. In this study, short-term milk output projections for Southeast Pen...
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There is a need for predictive and aggregate output response models suitable for answering questions about short-term changes in agricultural output. In this study, short-term milk output projections for Southeast Pennsylvania between 1961 and 1965 were derived with a linear programming, a recursive programming, and a regression model. The predictiveness of each model is evaluated by comparing its estimate of aggregate milk production with reported output for target years. Differences are expressed as percentage error from reported production. [ABSTRACT FROM AUTHOR]
A study of two applications programmed using three models of varying complexity reveals that implicit management of locality can produce code with performance comparable to code generated from explicit management of l...
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A study of two applications programmed using three models of varying complexity reveals that implicit management of locality can produce code with performance comparable to code generated from explicit management of locality.
Although there are certainly revolutionary advances in technology, their effect accumulates slowly and the ultimate impact often contradicts the initial prognostications.
Although there are certainly revolutionary advances in technology, their effect accumulates slowly and the ultimate impact often contradicts the initial prognostications.
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