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5th ESA International Conference on Spacecraft Guidance, Navigation and Control Systems

作者： Betts, John T. Erb, Sven O. Math. and Computing Technology The Boeing Company P.O. Box 3707 MC 7L-21 Seattle WA 98124-2207 United States

This paper describes the application of the transcription method to compute an optimal low thrust transfer from a geostationary transfer orbit around the earth to a specified lunar mission orbit. It is representative of the SMART-1 mission that will be conducted by ESA early in 2003. The spacecraft is equipped with electric propulsion powered by solar array. So the available thrust is no more than 0.073 Newton, while the initial mass of the satellite is 350 kg. This is a challenging class of optimal control problems since significant orbit manipulations require very long duration trajectories. The problem is also demanding because realistic forces due to earth oblateness and third-body perturbation often dominate the thrust. This approach combines a sparse nonlinear programming algorithm with a discretization of the trajectory and automated mesh refinement. The problem will be presented in detail and the optimization performance along with the optimized trajectory will be discussed.

关键词： Lunar missions

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OSCILLATION RESULTS FOR A SECOND ORDER NEUTRAL DELAY DIFFERENTIAL EQUATIONS

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Annals of Differential Equations 2003年第2期19卷 229-237页

作者：徐志庭贾保国马东魁 Dept.of Math. South China Normal UniversityGuangzhou 510631 Dept.of Scientific Computing and Computer Application Zhongshan UniversityGuangzhou 510275 Dept.of Applied Math. South China University of TechnologyGuangzhou 510641

Some new oscillation criteria are established for a second order neutral delay differential equations. These results improve oscillation results of Y.V. Rogo-vchenko for the retarded delay differential equations. The ... 详细信息

关键词： second order neutral delay differential equations oscillation

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A Modal Characterization of Nash Equilibrium

A Modal Characterization of Nash Equilibrium

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作者： Harrenstein, Paul Meyer, John-Jules Van der Hoek, Wiebe Witteveen, Cees Inst. of Info./Computing Sciences Utrecht University Utrecht Netherlands Computer Science Department University of Liverpool Liverpool United Kingdom Fac. of Elec. Eng. Math./Comp. Sci. Delft University of Technology Delft Netherlands

Multi-agent systems comprise entities whose individual decision making behavior may depend on one another's. Game-theory provides apposite concepts to reason in a math.matically precise fashion about such interactive and interdependent situations. This paper concerns a logical analysis of the game-theoretical notions of Nash equilibrium and its subgame perfect variety as they apply to a particular class of extensive games of perfect information. Extensive games are defined as a special type of labelled graph and we argue that modal languages can be employed in their description. We propose a logic for a multi-modal language and prove its completeness with respect to a class of frames that correspond with a particular class of extensive games. In this multimodal language (subgame perfect) Nash equilibria can be characterized. Finally, we show how this approach can formally be refined by using Prepositional Dynamic Logic (PDL), though we leave completeness as an open question.

关键词： Multi agent systems

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A dynamic upgrade mechanism based on publish/subscribe interaction

A dynamic upgrade mechanism based on publish/subscribe inter...

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26th Annual International Computer Software and Applications Conference

作者： Van De Laar, F. Chaudron, M.R.V. Eindhoven University of Technology Dept. of Math. and Computing Science Eindhoven Netherlands

ISBN: (纸本)0769517277

We advocate the use of publish/subscribe as an interaction style for upgradeable component-based systems. We present an architecture based on publish/subscribe that enables easy dynamic replacement of components. We describe the rationale behind design decisions relating to robustness, binding, upgrading and transfer of state. Furthermore, we illustrate our architecture using some scenarios.

关键词： Software engineering

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computing the Betti numbers of arrangements

Computing the Betti numbers of arrangements

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Proceedings of the 34th Annual ACM Symposium on Theory of computing

作者： Basu, Saugata Sch. of Math. and Coll. of Computing Georgia Institute of Technology Atlanta GA United States

In this paper, we consider the problem of computing the Betti numbers of an arrangement of n compact semi-algebraic sets, S1,..., Sn ⊂ k, where each Si is described using a constant number of polynomials with degrees bounded by a constant. Such arrangements are ubiquitous in computational geometry. We give an algorithm for computing -th Betti number, β(∪iSi), 0 ≤ ≤ k - 1, using O(n+2) algebraic operations. Additionally, one has to perform linear algebra on matrices of size bounded by O(n+1). All previous algorithms for computing the Betti numbers of arrangements, triangulated the arrangement giving rise to a complex of size O(n2k) in the worst case. To our knowledge this is the first algorithm for computing β(∪iSi) that does not rely on such a global triangulation, and has a graded complexity which depends on .

关键词： Computational geometry

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A graded quadrivalent logic for ordinal preference modelling: Loyola-like approach

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Fuzzy Optimization and Decision Making 2002年第1期1卷 93-111页

作者： Fortemps, Philippe Slowiński, Roman Department of Math. and O.R Mons Institute of Technology Rue de Houdain 9 B-7000 Mons Belgium Institute of Computing Science Poznań University of Technology Piotrowo 3A PL-60-965 Poznań Poland

We extend a quadrivalent logic of Belnap to graded truth values in order to handle graded relevance of positive and negative arguments provided in preferential information concerning ranking of a finite set of alternatives. This logic is used to design the preference modelling and exploitation phases of decision aiding with respect to the ranking problem. The graded arguments are presented on an ordinal scale and their aggregation leads to preference model in form of four graded outranking relations (true, false, unknown and contradictory). The exploitation procedure combines the min-scoring procedure with the leximin rule. Aggregation of positive and negative arguments as well as exploitation of the resulting outranking relations is concordant with an advice given by St. Ignatius of Loyola (1548) "how to make a good choice". © 2002 Kluwer Academic Publishers.

关键词： Decision making

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Gauging IT support strategies: User needs then and now 02

Gauging IT support strategies: User needs then and now

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Proceedings of the 30 Annual ACM SIGUCCS Fall Conference on Charting Bold Courses: New Worlds in User Services

作者： Samuel, John V. Peebles, Christopher S. Noguchi, Takuya Stewart, Craig A. UITS Ctr. for Statistical Math. Comp Indiana University Bloomington IN 47408 United States Res. and Academic Computing Dean for Information Technology Indiana University Bloomington IN 47405 United States Research and Academic Computing Indiana University Bloomington IN 47408 United States

ISBN: (纸本)9781581135640

Rapid changes in the IT field have placed a burden on educational institutions, which must decide how best to provide computing support for instruction and research. Institutions must determine the ideal balance of IT support with other educational needs in the academic community. Access to information technology is no longer a privilege held by a select few groups: instead, it has become a necessity in the academic environment. Since the late 1980's, computing support strategies at Indiana University have changed drastically to accommodate the changes in users' needs. In order to keep up with these changes, the University solicits input directly from users, allowing it to apply its scant and valuable computing support resources to where they are most needed. The annual IT survey conducted by the information technology organization has proven an invaluable tool in helping the University maintain one of the best academic computing support environments in the nation. Giving the end users an opportunity to provide input on what changes are needed in the University's IT environment has played a key role in the success of the support mechanisms. In addition, responses to the survey give an accurate picture of current needs and allow better projection of future needs of users. This allows the University to better serve its academic computing community without over-allocating resources that would be more useful elsewhere in the academic environment.

关键词： Information technology

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Optimal control of linear, stochastic systems with state and input constraints

Optimal control of linear, stochastic systems with state and...

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41st IEEE Conference on Decision and Control

作者： Batina, Ivo Stoorvogel, Anton A. Weiland, Siep Dept. of Math. and Computing Sci. Eindhoven Univ. Technology P.O. Box 513 5600 MB Eindhoven Netherlands Dept. of Info. Technol. and Syst. Delft Univ. of Technology P.O. Box 5031 2600 GA Delft Netherlands Dept. of Electrical Engineering Eindhoven Univ. of Technology P.O. Box 513 5600 MB Eindhoven Netherlands

In this paper we extend the work presented in the papers [1-3] where we considered optimal control of a linear, discrete time system subject to input constraints and stochastic disturbances. Here we basically look at the same problem but we additionally consider state constraints. We discuss several approaches for incorporating state constraints in a stochastic optimal control problem. We consider in particular a soft-constraint on the state constraints where constraint violation is punished by a hefty penalty in the cost function. Because of the stochastic nature of the problem, the penalty on the state constraint violation can not be made arbitrary high. We derive a condition on the growth of the state violation cost that has to be satisfied for the optimization problem to be solvable. This condition gives a link between the problem that we consider and the well known H∞ control problem.

关键词： Optimal control systems

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Fluid transients and fluid-structure interaction in flexible liquid-filled piping

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Applied Mechanics Reviews 2001年第5期54.0卷 455-481页

作者： Wiggert, David C. Tijsseling, Arris S. Dept. of Civ. and Environ. Eng. Michigan State University East Lansing MI 48824 United States Dept. of Math. and Computing Science Eindhoven University of Technology 5600 MB Eindhoven PO Box 513 Netherlands University of Michigan United States Michigan State University United States Dept. of Civ. and Environ. Eng. United States ASME United States ASCE United States Delft University of Technology Netherlands Delft Hydraulics Delft University Netherlands University of Dundee United Kingdom Eindhoven University of Technology Netherlands Royal Dutch Institute of Engineers Netherlands

Fluid-structure interaction in piping systems (FSI) consists of the transfer of momentum and forces between piping and the contained liquid during unsteady flow. Excitation mechanisms may be caused by rapid changes in flow and pressure or may be initiated by mechanical action of the piping. The interaction is manifested in pipe vibration and perturbations in velocity and pressure of the liquid. The resulting loads imparted on the piping are transferred to the support mechanisms such as hangers, thrust blocks, etc. The phenomenon has recently received increased attention because of safety and reliability concerns in power generation stations, environmental issues in pipeline delivery systems, and questions related to stringent industrial piping design performance guidelines. Furthermore, numerical advances have allowed practitioners to revisit the manner in which the interaction between piping and contained liquid is modeled, resulting in improved techniques that are now readily available to predict FSI. This review attempts to succinctly summarize the essential mechanisms that cause FSI, and present relevant data that describe the phenomenon. In addition, the various numerical and analytical methods that have been developed to successfully predict FSI will be described. Several earlier reviews regarding FSI in piping have been published;this review is intended to update the reader on developments that have taken place over the last approximately ten years, and to enhance the understanding of various aspects of FSI. There are 123 references cited in this review article.

关键词： Pipes vibrations pipe flow Fluid structure interaction transients reviews Pressure Vibration flexible structures

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Stability and convergence for the reform postprocessing Galerkin method *

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Nonlinear Analysis: Real World Applications 2000年第4期1卷 517-533页

作者： Yinnian, He Mattheij, R.M.M. Research Center for Applied Math Xi'an Jiaotong University Xi'an 710049 China Dept. of Math. and Computing Science Eindhoven University of Technology 5600 MB Eindhoven P.O. Box 513 Netherlands

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