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摄影记者们几乎无法扑捉到震后日本人的悲痛神情,他们脸上更多呈现出平静,地震与海啸过后的人们,在核辐射的阴影下仍能保持秩序与镇定,这是一种什么力量,有人将此归结为他们隐忍的气质,这样的灾后表现,让很多人对日本经济仍未完全丧失信心,尽管此前的20年,它的表现并不尽人意。 在海外资本回流参与灾后重建的背景下,日元升值在所难免;与此同时,也可能拉高美元的利率,毕竟日本仍是美债的重要力量。 相似文献
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继2008年6月1日《内控双刃剑》的封面报道之后,一年后的今天,本刊再次将目光聚焦内控,只是与上次不同的是,大环境已然变化。
一是,中国版“萨班斯法案”延期,主因在于金融危机下内控给企业带来的客观成本。二是,内部控制与风险管理事实上正在融合,曾经“厘不清”的内控的价值正在凸显。 相似文献
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设H为锐角△ABC的垂心,以H为圆心的任一圆,分别交与BC,AC,BA平行的中位线依次于P1,Q1,P2,Q2,P3,Q3,则
AP1=BP2=CP3=AQ1=BQ2=CQ3。 相似文献
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D. I. Piontkovskii 《Mathematical Notes》1999,65(5):582-589
Varieties of associative algebras over a field of characteristic zero are considered. Belov recently proved that, in any variety
of this kind, the Hilbert series of a relatively free algebra of finite rank is rational. At the same time, for three important
varieties, namely, those of algebras with zero multiplication, of commutative algebras, and of all associative algebras, a
stronger assertion holds: for these varieties, formulas that rationally express the Hilbert series of the free product algebra
via the Hilbert series of the factors are well known. In the paper, a system of counterexamples is presented which shows that
there is no formula of this kind in any other variety, even in the case of two factors one of which is a free algebra. However,
if we restrict ourselves to the class of graded PI-algebras generated by their components of degree one, then there exist
infinitely many varieties for each of which a similar formula is valid.
Translated fromMatematicheskie Zametki, Vol. 65, No. 5, pp. 693–702, May, 1999. 相似文献
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Covering-based rough sets,as a technique of granular computing,can be a useful tool for dealing with inexact,uncertain or vague knowledge in information systems.Matroids generalize linear independence in vector spaces,graph theory and provide well established platforms for greedy algorithm design.In this paper,we construct three types of matroidal structures of covering-based rough sets.Moreover,through these three types of matroids,we study the relationships among these matroids induced by six types of covering-based upper approximation operators.First,we construct three families of sets by indiscernible neighborhoods,neighborhoods and close friends,respectively.Moreover,we prove that they satisfy independent set axioms of matroids.In this way,three types of matroidal structures of covering-based rough sets are constructed.Secondly,we study some characteristics of the three types of matroid,such as dependent sets,circuits,rank function and closure.Finally,by comparing independent sets,we study relationships among these matroids induced by six types of covering-based upper approximation operators. 相似文献
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Paul Davidsson Stefan Johansson 《Computational & Mathematical Organization Theory》2006,12(2-3):169-180
Based on a classification of artificial societies and the identification of four different types of stakeholders in such societies,
we investigate the potential of norm-governed behavior in different types of artificial societies. The basis of the analysis
is the preferences of the stakeholders and how they influence the state of the society. A general conclusion drawn is that
the more open a society is the more it has to rely on agent owners and designers to achieve norm-governed behavior, whereas
in more closed societies the environment designers and owners may control the degree of norm-governed behavior.
Paul Davidsson is professor at the Department of Systems and Software Engineering, School of Engineering, Blekinge Institute of Technology,
Sweden. He received his Ph.D. in Computer Science in 1996 from Lund University, Sweden. His research interests include the
theory and application of multi-agent systems, autonomous agents, and machine learning. Application areas include logistics,
transport systems, district heating systems, building automation, and telecommunications systems. The results of this work
have been reported in more than 75 peer-reviewed scientific articles published in international journals and conference proceedings.
Moreover, he has been the co-editor of three books on Multi Agent Based Simulation and member of program committees of numerous
international conferences, such as the International Joint Conference on Autonomous Agents and Multi-Agent Systems
Stefan Johansson is an assistant professor at Department of Systems and Software Engineering, Blekinge Institute of Technology, Sweden, where
he also finished his PhD in 2002. The main research areas cover coordination issues in multi-agent systems and theories of
autonomous agents. Applications of special interests are agents in game ai, robotics, telecommunication networks. On his list
of publications are more than 35 peer-reviewed papers published in conference proceedings and scientific journals in the areas
of agents, ai, robotics and games. He has also been a member of a variety of programme committees of scientific conferences,
including e.g. Intelligent Agent Technology. 相似文献
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James Singletary 《Mechanics of Composite Materials》2000,36(4):319-326
Results of single transverse compression testing of PPTA and PIPD fibers, using a novel test device, are presented and discussed. In the tests, short lengths of single fibers are compressed between two parallel, stiff platens. The fiber elastic deformation is analyzed as a Hertzian contact problem. The inelastic deformation is analyzed by elastic-plastic FE simulation and by laser-scanning confocal microscopy of the compressed fibers ex post facto. The results obtained are compared to those in the literature and to the theoretical predictions of PPTA fiber transverse elasticity based on PPTA crystal elasticity.Presented at the 11th International Conference on Mechanics of Composite Materials (Riga, June 11–15, 2000).3TEX, Inc. 109, MacKenan Drive, Cary, North Carolina 27511, USA. Published in Mekhanika Kompozitnykh Materialov, Vol. 36, No. 4, pp. 533–544, March–April, 2000. 相似文献
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This paper examines the basic problem of estimating the state of a system described by a set of dynamical equations. The state estimation is performed by means of optimal filtering techniques in which the state observation is given by a set of nonlinear equations.The basic issue encountered in most engineering problems is the availability of more observable information than the processor can effectively process in real-time, while performing full optimal filtering on all available observable data. To alleviate this deficiency, an algorithm is developed in which the rate of information processing is kept at a high value, while the system statistics are evaluated at a much slower rate.The method utilizes a combination of fast and slow filtering loops, in which the observable data are processed at a high rate during the fast loop, while the system error covariance, gain computations, and all other system statistics are processed at a lower rate in the slow loop. Methods are provided to resolve any incompatibility in the system statistics resulting from this fast-loop/slow-loop processing combination.Applications describing problems pertaining to aircraft navigation are presented. Specifically, applications to aircraft navigation through a satellite network are studied. Appropriate simulation results from the above studies are shown.This work was performed under contract with the Department of the Air Force, Space and Missile Organization (SAMSO), Los Angeles, California, Contract No. F04-701-75-C-0180.The authors are indebted to Dr. C. Johnson, GPS System Engineer, Mr. G. Consolver, GPS Software Manager, and Mr. W. Riley, Communications/Navigation Department, Texas Instruments for their continuous encouragement in the course of this work. Also, they are indebted to Major M. Birnbaum, SAMSO, for his constructive criticism on the conceptual design of this work, and to Mr. A. Bierman, Aerospace Corporation, for kindly providing simulation data of aircraft trajectories. Finally, the authors would like to express their gratitude to Dr. N. Carlson, Intermetrics, for valuable consultation during the progress of this work.Portions of this paper were presented by the senior author at the GSP Conference, Plan 76, IEEE Position, Location, and Navigation Symposium, San Diego, California, 1976. 相似文献
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L. Barrière 《Discrete Mathematics》2009,309(12):3871-871
A generalization of both the hierarchical product and the Cartesian product of graphs is introduced and some of its properties are studied. We call it the generalized hierarchical product. In fact, the obtained graphs turn out to be subgraphs of the Cartesian product of the corresponding factors. Thus, some well-known properties of this product, such as a good connectivity, reduced mean distance, radius and diameter, simple routing algorithms and some optimal communication protocols, are inherited by the generalized hierarchical product. Besides some of these properties, in this paper we study the spectrum, the existence of Hamiltonian cycles, the chromatic number and index, and the connectivity of the generalized hierarchical product. 相似文献
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N. V. Novikov A. L. Maystrenko V. I. Kushch S. A. Ivanov 《Mechanics of Composite Materials》2006,42(3):253-262
The efficiency of hot-pressed diamond-containing composite materials (DCM) for various tool applications is greatly affected
by microdefects, namely, the residual porosity of the metal matrix, damaged diamond grains, and imperfect diamond-matrix interfaces.
An instrumental evaluation of these microdefects, predetermining the quality of a tool equipped with DCM, is rather difficult
due to the small size, the nonstandard shape, and the strong heterogeneity of specimens. Proposed here is an alternative,
nondestructive technique of DCM quality rating, which includes the measurement of electric resistance and thermal conductivity
of diamond-containing composites and processing the obtained data by the methods of composite mechanics. It exploits the fact
that diamond, being a dielectric, possesses an extremely high thermal conductivity, which allows estimating the residual porosity
of a sintered metal matrix from the ratio of specific electric resistances, one being measured and another predicted by a
theory. These data, in turn, are utilized to predict the thermal conductivity ofDCMwith an imperfect matrix. Matching with
experiments, after solving the inverse problem gives the thermal resistance of diamond-matrix interface, which, within the
frame work of the given model, simulates the damage of both the diamond grains and their bonds with the matrix. Thus, the
numerical rating of quality is given in terms of two dimensionless parameters. The first one, 0 < K < 1, reflects the quality of the sintered metal matrix, whereas the second one, 0 < R <1, is an aggregate measure of the integrity of diamond grains and the perfection degree of composite interfaces. The quite
satisfactory agreement observed between the theory and experiment confirms the efficiency of the technique and the reliability
of the data obtained.
Russian translation published in Mekhanika Kompozitnykh Materialov, Vol. 42, No. 3, pp. 361–374, May–June, 2006. 相似文献
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Jan J. Sławianowski Vasyl Kovalchuk Agnieszka Martens Barbara Gołubowska Eliza E. Rożko 《Mathematical Methods in the Applied Sciences》2012,35(1):17-42
Discussed are some geometric aspects of the phase space formalism in quantum mechanics in the sense of Weyl, Wigner, Moyal, and Ville. We analyze the relationship between this formalism and geometry of the Galilei group, classical momentum mapping, theory of unitary projective representations of groups, and theory of groups algebras. Later on, we present some generalization to quantum mechanics on locally compact Abelian groups. It is based on Pontryagin duality. Indicated are certain physical aspects in quantum dynamics of crystal lattices, including the phenomenon of ‘Umklapp–Prozessen’. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献