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作者： Hemker, Thomas Fowler, Kathleen R. Farthing, Matthew W. von Stryk, Oskar Department of Computer Science Simulation Systems Optimization and Robotics Group Technische Universität Darmstadt Hochschulstraße 10 64289 Darmstadt Germany Clarkson Center for the Environment Department of Mathematics Clarkson University Potsdam NY 13676-5815 United States Center for the Integrated Study of the Environment Department of Environmental Sciences and Engineering University of North Carolina at Chapel Hill Chapel Hill NC 27599-7431 United States

Efficient and powerful methods are needed to overcome the inherent difficulties in the numerical solution of many simulation-based engineering design problems. Typically, expensive simulation codes are included as black-box function generators;therefore, gradient information that is required by mathematical optimization methods is entirely unavailable. Furthermore, the simulation code may contain iterative or heuristic methods, low-order approximations of tabular data, or other numerical methods which contribute noise to the objective function. This further rules out the application of Newton-type or other gradient-based methods that use traditional finite difference approximations. In addition, if the optimization formulation includes integer variables the complexity grows even further. In this paper we consider three different modeling approaches for a mixed-integer nonlinear optimization problem taken from a set of water resources benchmarking problems. Within this context, we compare the performance of a genetic algorithm, the implicit filtering algorithm, and a branch-and-bound approach that uses sequential surrogate functions. We show that the surrogate approach can greatly improve computational efficiency while locating a comparable, sometimes better, design point than the other approaches. © Springer science+Business Media, LLC 2008.

关键词： Iterative methods

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Editorial

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Theory in Biosciences 2008年第2期127卷 67-68页

作者： Jost, Jürgen Helbing, Dirk Lörincz, András Middendorf, Martin Max Planck Institute for Mathematics in the Sciences Leipzig Germany Department of Humanities and Social Sciences Chair of Sociology in particular of Modeling and Simulation ETH Zurich Zurich Switzerland Department of Information Systems Eötvös Loránd University Budapest Hunhary Department of Computer Science University of Leipzig Leipzig Germany

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High pressure structural phase transitions in Sr from ab initio calculations

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Physical Review B 2008年第17期77卷 174118-174118页

作者： A. Phusittrakool T. Bovornratanaraks R. Ahuja U. Pinsook Large-Scale Simulation Research Laboratory National Electronics and Computer Technology Center Pathumthani 12120 Thailand Department of Physics Faculty of Science Chulalongkorn University Bangkok 10330 Thailand Condensed Matter Theory Group Department of Physics Uppsala University Box 530 SE-751 21 Uppsala Sweden Applied Materials Physics Department of Materials and Engineering Royal Institute of Technology (KTH) S-100 44 Stockholm Sweden

The pressure-induced phase transition in strontium, including the recent experimental observation of high-pressure phase Sr-IV, was investigated theoretically using the projector augmented wave method. We also concentrated on the experimentally observed β-tin structure as this structure has never been found in any other alkaline-earth metals. The fcc-bcc phase transition was reproduced, but Sr-IV was found to be energetically more stable than the β-tin structure at all pressures. By considering enthalpy, the sequence of the phase transitions along the pressure range is fcc→bcc→Sr-IV. With some detailed examination, we concluded that the β-tin structure is either a metastable state or a coexisting phase, and further experimental investigation is suggested.

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Complexities of simulating a hybrid agent-landscape model using multi-formalism composability

Complexities of simulating a hybrid agent-landscape model us...

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2007 Agent Directed simulation Symposium, ADS 2007

作者： Mayer, Gary R. Sarjoughian, Hessam S. Arizona Center for Integrative Modeling and Simulation Computer Science and Engineering Department School of Computing and Informatics Arizona State University TempeAZ United States

ISBN: (纸本)1565553136

Hybrid agent-landscape models are used as an environment in which to study humans, the environment, and their dynamics. To provide flexibility in model design, expressiveness, and modification, the environment models and human agent models should be developed independently. While retaining each model's individuality, the models can be composed to create a model of a complex, hybrid agent-landscape system. This should allow for a much more in-depth analysis of each model independently, as well as a study of their interactions. To create such a modeling environment requires a look beyond a simple interface between two models. It may require that the models' formalisms be composed, their execution be synchronized, their architectures be integrated, and a common visualization be created to provide a whole-system data view during simulation. This paper discusses the complexities of such an undertaking.

关键词： Cellular automata

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An exploration-based taxonomy for emergent behavior analysis in simulations

An exploration-based taxonomy for emergent behavior analysis...

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2007 Winter simulation Conference, WSC

作者： Gore, Ross Reynolds Jr., Paul F. Modeling and Simulation Technology Research Initiative Department of Computer Science University of Virginia 151 Engineer's Way P.O. Box 400740 Charlottesville VA 22904-4740 United States

ISBN: (纸本)1424413060

Emergent behaviors in simulations require explanation, so that valid behaviors can be separated from design or coding errors. We present a taxonomy, to be applied to emergent behaviors of unknown validity. Our goal is to facilitate the explanation process. Once a user identifies an emergent behavior as a certain type within our taxonomy, exploration can commence in a manner befitting that type. Exploration based on type supports narrowing of possibilities and suggests exploration methods, thus facilitating the exploration process. Ideally, a taxonomy would be robust, allowing reasonable variation in behavior type assignment without penalty in cost or correctness during the exploration process. The taxonomy we present is robust, comprehensive and suitable for use with our established emergent behavior exploration methods. In addition to the taxonomy, we present our design rationale, and a summary of results from a test application of our taxonomy. © 2007 IEEE.

关键词： Taxonomies

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Interactive particle visualization with advanced shading models using lazy evaluation

Interactive particle visualization with advanced shading mod...

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7th Eurographics Symposium on Parallel Graphics and Visualization, EGPGV 2007

作者： Gribble, Christiaan P. Parker, Steven G. Visual Simulation Group Department of Computer Science Grove City College Scientific Computing and Imaging Institute School of Computing University of Utah United States

ISBN: (纸本)9783905673500

Particle-based simulation methods are used to model a wide range of complex phenomena and to solve time-dependent problems of various scales. Effective visualizations of the resulting state will communicate subtle changes in the three-dimensional structure, spatial organization, and qualitative trends within a simulation as it evolves. We describe a visualization process targeting upcoming, highly parallel multicore desktop systems that enables interactive navigation and exploration of large particle datasets rendered with illumination effects from advanced shading models. These expensive illumination effects are evaluated lazily by decoupling interactive display and high quality rendering. We explore the performance characteristics of this approach and demonstrate its effectiveness using several large particle datasets. © The Eurographics Association 2007.

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An ontology-based dictionary of understanding as a basis for software agents with understanding abilities

An ontology-based dictionary of understanding as a basis for...

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2007 Agent Directed simulation Symposium, ADS 2007

作者： Ören, Tuncer I. Ghassem-Aghaee, Nasser Yilmaz, Levent M and SNet Ottawa Center of the MISS SITE University of Ottawa OttawaON Canada Beykent University Istanbul Turkey Department of Computer Engineering University of Isfahan Isfahan Iran M and SNet: Auburn Modeling and Simulation Laboratory Computer Science and Software Engineering Auburn University AuburnAL United States

Nearly 60 types of machine understanding is presented in an ontology-based dictionary as a basis for the development of software agents with understanding abilities. Then a framework for software agents is presented.

ISBN: (纸本)1565553136

关键词： Software agents

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A co-design modeling approach for computer network systems 07

A co-design modeling approach for computer network systems

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simulation Winter Conference

作者： Weilong Hu Hessam S. Sarjoughian Arizona Center for Integrative Modeling & Simulation Computer Science and Engineering Department Arizona State University Tempe AZ USA

ISBN: (纸本)9781424413065

Co-design modeling is considered key toward handling the complexity and scale of network systems. The ability to separately specify the software and hardware aspects of computer network systems offers new capabilities beyond what is supported in modeling frameworks and tools such as NS-2 and OPNET. The DEVS/DOC simulation environment supports logical co-design specification based on the distributed object computing (DOC) abstract model. To overcome DEVS/DOC's lack of support for visual and persistent modeling, this paper presents SESM/DOC, a novel approach, which is based on the scaleable entity structure modeler (SESM), a component-based modeling framework. This approach supports logical, visual and persistent modeling. Modelers can develop software and hardware models separately and systematically integrate them to specify a family of computer network system designs. This paper details the SESM/DOC co-design modeling approach with the help of a search engine system example, and presents a discussion for future research directions.

关键词： computer networks Hardware Computational modeling Distributed computing Routing computer simulation Software tools Application software Network synthesis Network topology

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Application of combined discrete-event simulation and optimization models in semiconductor enterprise manufacturing systems 07

Application of combined discrete-event simulation and optimi...

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simulation Winter Conference

作者： Gary Godding Hessam Sarjoughian Karl Kempf Arizona Center for Integrative Modeling & Simulation Computer Science and Engineering Department Arizona State University Tempe AZ USA Corporate Planning and Logistics Group Intel Corporation Chandler AZ USA

ISBN: (纸本)9781424413065

It is a common practice to use simulation for validating different types of control and planning algorithms. However, the science of how to rigorously integrate simulation and decision models is not well understood and becomes critically important as the complexity and scale of these models increase. In our research, we have developed a methodology for integrating different types of models using a Knowledge Interchange Broker (KIB). In this paper we describe a supply-chain semiconductor application where the KIB has been used as an integral part of developing and deploying a commercial Model Predictive Control model for use in operating a multi-billion dollar supply chain. The simulation based experiments facilitated developing and validating the controller design and data automation for a real-world semiconductor manufacturing system.

关键词： Discrete event simulation Manufacturing systems Predictive models Semiconductor device manufacture Computational modeling Predictive control Virtual manufacturing Application software Manufacturing automation Discrete event systems

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Control approach for a novel high power-to-weight robotic actuator scalable in force and length

Control approach for a novel high power-to-weight robotic ac...

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IEEE/ASME (AIM) International Conference on Advanced Intelligent Mechatronics

作者： Robert Kratz Maximilian Stelzer Martin Friedmann Oskar von Stryk Simulation Systems Optimization and Robotics Group Department of Computer Science Technische Universität Darmstadt Darmstadt Germany

The development of a control approach for a novel, soundless, lightweight and multifunctional shape memory alloy (SMA) actuator scalable in force and length for personal assistance or home-help robots is presented in this paper. The SMA actuator is based on lightweight bundles of thin wires of prestrained shape memory alloy that change their length when heated above their transformation temperature. The design approach of the actuator allows arranging the point of actuation in any direction and ensures a short cool down time to guarantee a frequency of contraction/stress cycles that is high enough to allow fast joint motions. This is needed for the generation of fast joint motions. For the use of the actuator the novel control approach has been experimentally validated. The approach uses the resistance of the actuator as a linear position encoder and there are no additional external sensors needed. The application of the new actuator to a novel lightweight humanoid robot is outlined. One advantage of the actuator over electric motors lies in the large variety of user-defined points of actuation of the in pull-force and length free scalable actuators and the high power-to-weight ratio. The results demonstrate that it is possible to build a large humanoid robot actuated with SMA actuator in a new way.

关键词： Force control Actuators Shape memory alloys Humanoid robots Shape control Lighting control Wires Temperature Frequency Stress

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