This paper describes a generalization of the "labelling" search strategy and its application to scheduling problems. The assignment of a value to the selected variable is replaced by reduction of the domain ...
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This article outlines a graphical software package for performance and dependability modeling with deterministic and stochastic Petri nets (DSPNs). The package is called DSPNexpress because its main scientific contrib...
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This article outlines a graphical software package for performance and dependability modeling with deterministic and stochastic Petri nets (DSPNs). The package is called DSPNexpress because its main scientific contribution lies in its efficient numerical solution component. The development of DSPNexpress has been motivated by the lack of a software package for an efficient numerical analysis of Deterministic and stochastic Petri nets (DSPNs) and the complexity requirements imposed by evaluating design alternatives for hardware and software components of multicomputer systems. The main scientific contribution of DSPNexpress lies in its efficient numerical solution component. The version 1.3 of DSPNexpress solves complex DSPNs with four orders of magnitude less CPU time than the previously known numerical method. As a consequence, DSPNexpress is able to calculate steady-state solutions of complex DSPNs with reasonable computational effort on a modern workstation (e.g. a DSPN with 100000 tangible marking and 5000000 state transitions with mild stiffness can be solved in 1 hour of CPU time on a Sun Spare station 2). The article summarizes the main innovative features of the software package DSPNexpress.
The paper presents a taxonomy of the existing forms of parallel computerarchitectures, based on the characteristics of the hardware architecture and the abstract machine layered upon it. The abstract machine reflects...
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The paper presents a taxonomy of the existing forms of parallel computerarchitectures, based on the characteristics of the hardware architecture and the abstract machine layered upon it. The abstract machine reflects the programming models provided. The main classes of hardware architectures are: physically shared memory systems and distributed memory systems. Distributed memory systems may be remote memory access architectures or message passing architectures. The major forms of abstract machine architecture are: message passing systems and logically shared memory architectures. Three solutions for logically shared memory architectures are known (1) distributed shared memory architectures, (2) multi-threaded architectures, and (3) virtual shared memory architectures. All three types are discussed in detail under the aspects of performance, programmability, and scalability, and their corresponding programming paradigms are characterized. The implications of the three concepts on node architecture and the requirements of latency minimization or latency hiding are discussed and illustrated by examples taken from pioneering realizations of the three kinds of architecture such as DASH, *T, and MANNA.
We point out some errors in the combinatorial approach for the steady-state analysis of a deterministic and stochastic Petri net (DSPN) presented by M. Lu, D. Zhang, and T. Murata (1990). However, the methodology for ...
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We point out some errors in the combinatorial approach for the steady-state analysis of a deterministic and stochastic Petri net (DSPN) presented by M. Lu, D. Zhang, and T. Murata (1990). However, the methodology for analyzing the self-stability of fault-tolerant clock synchronisation (FCS) systems introduced in that paper is applicable for FCS systems with many clocking modules, even if the combinatorial approach is not valid. This is due to the progress in improving the efficiency of the DSPN solution algorithm made in recent years. We show that the explicit computation of the steady-state solution of the DSPN can be performed with reasonable computational effort on a modern workstation by the software package DSPNexpress.< >
The article deals with rationale and concepts of a programming model for massive parallelism. We mention the basic properties of massively parallel applications and develop a programming model for data parallelism on ...
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The article deals with rationale and concepts of a programming model for massive parallelism. We mention the basic properties of massively parallel applications and develop a programming model for data parallelism on distributed-memory computers. Its key features are a suitable combination of homogeneity and heterogeneity aspects, a unified representation of data point configuration and interconnection schemes by explicit virtual data topologies, and various synchronization schemes and nondeterminisms. The outline of the linguistic representation and the abstract executional model are given.< >
A concept for an air pollution simulation environment to predict and manage smog situations is presented consisting of the necessary data bases, a mesoscale meteorological model, an air chemistry model, and decision s...
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A concept for an air pollution simulation environment to predict and manage smog situations is presented consisting of the necessary data bases, a mesoscale meteorological model, an air chemistry model, and decision support tools including result visualization. Simulation runs and scenario analyses of such numerically complex models take hours of computing time, even on today's supercomputers. Therefore a strategy for model decomposition and implementation on massively parallel computers is described. Simulation results are shown for an ozone smog situation in Berlin.
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