共查询到20条相似文献,搜索用时 46 毫秒
1.
Guangda Hu Xuerong Mao Minghui Song 《Journal of Mathematical Analysis and Applications》2009,355(2):783-3109
Consider a given system under regime switching whose solution grows exponentially, and suppose that the system is subject to environmental noise in some regimes. Can the regime switching and the environmental noise work together to make the system change significantly? The answer is yes. In this paper, we will show that the regime switching and the environmental noise will make the original system whose solution grows exponentially become a new system whose solutions will grow at most polynomially. In other words, we reveal that the regime switching and the environmental noise will suppress the exponential growth. 相似文献
2.
《Chaos, solitons, and fractals》2005,23(2):683-688
By imposing various auxiliary conditions connected to supersymmetry, colours and chirality, three minimally extended versions of the standard model are proposed.Based on these tentative models, it is possible to predict that few new particles are very likely to be found experimentally in the near future and that these particles will be closely related to the Higgs mechanism. 相似文献
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U. Zhle 《Mathematische Nachrichten》1988,137(1):35-48
Regard a large population of infinitesimal particles (i.e. a measure) in the case, when the particles evolve (i.e. move, branch, die) independently of each other. Those evolutions we will call localizable. In the present part of this paper we answer at first the question about the structure of localizable evolutions, which take place in one step (independent clustering of measures). In localizable evolutions one can follow the path of any particle (and their predecessors) surviving up to some fixed time. The totality of these paths is the backward tere corresponding to this time point. In the case of continuous time localizable Markov evolutions the random backward tree measure is constructed via finite-dimensional distributions using the extension theorem from part I. 相似文献
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《Finite Fields and Their Applications》2003,9(2):187-193
Recently, Shin and Sung found new identities for Kloosterman sums over F2m with odd m. They posed the question whether similar results could be obtained for even m. In this paper, we will give a positive answer to this question. We will present new results that hold for any m and include as special cases the results of Shin and Sung in the case where m is odd. 相似文献
5.
In this work we study the fixed point property for nonexpansive self-mappings defined on convex and closed subsets of a CAT(0) space. We will show that a positive answer to this problem is very much linked with the Euclidean geometry of the space while the answer is more likely to be negative if the space is more hyperbolic. As a consequence we extend a very well known result of W.O. Ray on Hilbert spaces. 相似文献
6.
本文以有限元法的思想为基础,引用Diracδ函数和Heaviside step函数,将梁的弯曲问题的初参数法推广应用到杆系结构,并据此改进超静定结构分析中的混合法,提出空间杆系结构内力与变位分析的一种新方法.采用本文提供的新方法分析杆系结构的内力与变位的问题,可使整个推导过程与所得解答更加简洁精确. 相似文献
7.
A. S. Fokas E. P. Papadopoulou Y. G. Saridakis M. J. Ablowitz 《Studies in Applied Mathematics》1989,81(2):153-180
We consider a certain cellular automaton recently introduced by Park, Steiglitz, and Thurston. By introducing appropriate mathematical notation, the interaction of simple particles evolving according to this automaton rule is completely characterized analytically. It is found that: (1) If two particles have different speed and they interact, then they interact solitonically and, although they may interact a number of times, they finally separate with the faster particle moving in front of the slower one. (2) If two particles have the same speed and are close enough so that they interact, there exist two cases: either they will interact only once and then they will separate, travelling independently of each other, or they will form a new periodic configuration by interacting forever. 相似文献
8.
Paul R. Rosenbaum 《Journal of computational and graphical statistics》2013,22(4):381-403
Abstract The task of searching for the best element or a good element in a large set P is central to many problems in artificial intelligence and related fields. Often, heuristic information is used to reduce the scope of the search; however, in many instances, this information carries no guarantee of good performance. This article begins with an arbitrary heuristic search procedure and supplies it with a confidence statement of the following form: With specified high probability β, the output of the confidence procedure will be among the best 100α% of the elements of P. The confidence procedure will report either the outcome of the heuristic search or a better alternative with the required properties; that is, it will either certify that the heuristic answer has the desired confidence property or it will produce a better answer having the property. The approach involves combining heuristic search with a form of heuristic sampling that tends to sample the better elements of P. The sample is designed in such a way that the best element in the sample has the desired confidence property—if the answer produced by the heuristic search is better still, it inherits the confidence property. Various devices permit the sampling procedure to retain its confidence property while (1) moving the sample in the direction suggested by the heuristic, (2) adjusting the heuristic preference in response to what is learned during sampling, and (3) reorganizing the sampling whenever promising discoveries are made by chance. 相似文献
9.
The newest answer of German education authorities to the problems of learning, the so called ?Bildungsstandards”, is far away from any suitability. the more than forty years old dream of R. Mager in ?Preparing Objectives for Programmed Instruction” has got a great resonance in Germany too in that time. It was to early. Today we can realize this dream of modern learning environments in the world wide web: E-Testing as the base of successful E-Learning. The ?Dortmunder Manifest” presents the requirements. An adaptive basic program system in HTML/PHP with the respective properties to offer such checks will be given. A new form of evaluation is suggested. 相似文献
10.
Lü Fang 《数学学报(英文版)》1992,8(2):189-203
In this paper it will be shown that the spectrum of every unicellular unilateral weighted shift operator on a symmetric Banach
space is the singleton set {0}. From this, we give an affirmative answer to Rosenthal-Shields' problem.
Project supported by the National Natural Science Foundation of China 相似文献
11.
Dexter F 《OR manager》2005,21(3):12, 14, 16
Because the medical deadline is determined in hours, there is a precise mathematical definition for OR efficiency, and the impact on patient delays can be estimated. The priorities described above will give a single answer to a sequence of urgent cases. 相似文献
12.
C Beyrouthy E K Burke D Landa-Silva B McCollum P McMullan A J Parkes 《The Journal of the Operational Research Society》2009,60(1):130-143
There is a perception that teaching space in universities is a rather scarce resource. However, some studies have revealed that in many institutions it is actually chronically under-used. Often, rooms are occupied only half the time, and even when in use they are often only half full. This is usually measured by the ‘utilization’ which is defined as the percentage of available ‘seat-hours’ that are employed. Within real institutions, studies have shown that this utilization can often take values as low as 20–40%. One consequence of such a low level of utilization is that space managers are under pressure to make more efficient use of the available teaching space. However, better management is hampered because there does not appear to be a good understanding within space management (near-term planning) of why this happens. This is accompanied, within space planning (long-term planning) by a lack of experise on how best to accommodate the expected low utilizations. This motivates our two main goals: (i) To understand the factors that drive down utilizations, (ii) To set up methods to provide better space planning. Here, we provide quantitative evidence that constraints arising from timetabling and location requirements easily have the potential to explain the low utilizations seen in reality. Furthermore, on considering the decision question ‘Can this given set of courses all be allocated in the available teaching space?’ we find that the answer depends on the associated utilization in a way that exhibits threshold behaviour: There is a sharp division between regions in which the answer is ‘almost always yes’ and those of ‘almost always no’. Through analysis and understanding of the space of potential solutions, our work suggests that better use of space within universities will come about through an understanding of the effects of timetabling constraints and when it is statistically likely that it will be possible for a set of courses to be allocated to a particular space. The results presented here provide a firm foundation for university managers to take decisions on how space should be managed and planned for more effectively. Our multi-criteria approach and new methodology together provide new insight into the interaction between the course timetabling problem and the crucial issue of space planning. 相似文献
13.
Ping Lin. 《Mathematics of Computation》2003,72(242):657-675
In many applications materials are modeled by a large number of particles (or atoms) where any one of particles interacts with all others. Near or nearest neighbor interaction is expected to be a good simplification of the full interaction in the engineering community. In this paper we shall analyze the approximate error between the solution of the simplified problem and that of the full-interaction problem so as to answer the question mathematically for a one-dimensional model. A few numerical methods have been designed in the engineering literature for the simplified model. Recently much attention has been paid to a finite-element-like quasicontinuum (QC) method which utilizes a mixed atomistic/continuum approximation model. No numerical analysis has been done yet. In the paper we shall estimate the error of the QC method for this one-dimensional model. Possible ill-posedness of the method and its modification are discussed as well.
14.
Nicolas Crouseilles 《Comptes Rendus Mathematique》2002,334(9):827-832
Our purpose is to derive a model describing the evolution of charged particles in a plasma, at various scales following their kinetic energy. Fast particles will be described through a collisional kinetic equation of Boltzmann type. This equation will be coupled with a drift-diffusion model that describes the evolution of slower particles. The main interest of this approach is to reduce the cost of numerical simulations. This gain is due to the use of a macroscopic model for slow particles instead of a kinetic model for all the particles, which would involve a larger number of variables. To cite this article: N. Crouseilles, C. R. Acad. Sci. Paris, Ser. I 334 (2002) 827–832. 相似文献
15.
Summary. This article deals with inequality measures on income distributions. These measures are assumed to fulfil common axioms like the Principle of Progressive Transfers, Normalization, and Symmetry. Strict Monotonicity will be defined and is included in the basic set of axioms. If the measures are especially based on bilateral comparisons and if two additional conditions are fulfilled the bilateral inequality measure must be proportional to the absolute distance of the two incomes involved. It is remarkable that all these conditions do not give an answer whether an inequality measure for two incomes should be a quasi-convex or a quasi-concave function. This question is controversely discussed in economic research. Our surprising answer, however, is given by use of RAO's statistic concept defining the diversity of a population. 相似文献
16.
It is common sense to notice that one needs fewer digits to code numbers in ternary than in binary; new names are about log32 times shorter. Is this trade-off a consequence of the special coding scheme? The answer is negative. More generally, we argue that the answer to the question, stated in the title and formulated to the first author by C. Rackhoff, is in fact negative. The conclusion will be achieved by studying the role of the size of the alphabet in constructing instantaneous codes for all natural numbers, and defining random strings and sequences. We show that there is no optimal instantaneous code for all positive integers, and the binary is the worst possible. Codes over a fixed alphabet can be indefinitely improved themselves, but only “slightly”; in contrast, changing the size of the alphabet determines a significant, not linear, improvement. The key relation describing the above phenomenon can be expressed in terms of Chaitin complexity: changing the size of the coding alphabet from q to Q, 2 ≤ q < Q, results in an improvement of the complexity by a factor og log q. As a consequence, a string avoiding consistently a fixed letter is not random. In binary, this corresponds to a trivial situation. In the nonbinary case the distinction is relevant: more than 3.2n ternary strings of length n are not random (many of these strings are binary random). This phenomenon is even sharper for infinite sequences. 相似文献
17.
一种加入创新粒子的粒子群 总被引:1,自引:0,他引:1
粒子群算法是一种基于群体智能的随机并行算法,它在很多优化问题中都得到了比较好的应用。本文针对粒子群容易陷入局部最优解,提出了一种加入创新粒子的粒子群,实验模拟结果表明加入创新粒子的粒子群有更好的结果和收敛速度。 相似文献
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Our purpose is to derive a model describing the evolution of particles at various scales following their kinetic energy. Fast particles will be described through a collisional kinetic equation of Boltzmann-BGK type. This equation will be coupled with a fluid model (Euler equations) that describes the evolution of slower particles. The main interest of this approach is to reduce the cost of numerical simulations. To cite this article: N. Crouseilles et al., C. R. Acad. Sci. Paris, Ser. I 336 (2003). 相似文献