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941.
We study a class of weak solutions to hyperbolic systems of conservation (balance) laws in one space dimension, called stratified solutions. These solutions are bounded and ``regular' in the direction of a linearly degenerate characteristic field of the system, but not in other directions. In particular, they are not required to have finite total variation. We prove some results of local existence and uniqueness.
942.
Z. Eisler J. Kertész 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,51(1):145-154
We reanalyze high resolution data from the New York Stock
Exchange and find a monotonic (but not power law) variation of the mean value per trade,
the mean number of trades per minute and the mean trading activity
with company capitalization. We show that the second moment of the
traded value distribution is finite. Consequently, the Hurst
exponents for the corresponding time series can be calculated. These
are, however, non-universal: The persistence grows with larger
capitalization and this results in a logarithmically increasing Hurst exponent. A similar
trend is displayed by intertrade time intervals.
Finally, we demonstrate that the distribution of the intertrade times is
better described by a multiscaling ansatz than by simple gap scaling. 相似文献
943.
The theory of hyperbolic conservation laws has been successfully applied to the study of vehicular traffic flows. We present here some models showing phase transitions, that in terms of traffic flows correspond to two distinct behaviors, free or congested. 相似文献
944.
K. M. Mogare D. V. Sheptyakov R. Bircher H.-U. Güdel M. Jansen 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,52(3):371-376
We present a novel model to simulate real social networks of complex
interactions, based in a system of colliding particles
(agents).
The network is build by keeping track of the collisions and evolves in
time with correlations which emerge due to the mobility of the agents.
Therefore, statistical features are a consequence only of local
collisions among its individual agents.
Agent dynamics is realized by an event-driven algorithm of collisions
where energy is gained as opposed to physical systems which have
dissipation.
The model reproduces empirical data from networks of sexual
interactions, not previously obtained with other approaches. 相似文献
945.
André Adler 《Central European Journal of Mathematics》2006,4(1):1-4
Consider independent and identically distributed random variables {X
nk, 1 ≤ k ≤ m, n ≤ 1} from the Pareto distribution. We select two order statistics from each row, X
n(i) ≤ X
n(j), for 1 ≤ i < j ≤ = m. Then we test to see whether or not Laws of Large Numbers with nonzero limits exist for weighted sums of the random variables
R
ij = X
n(j)/X
n(i). 相似文献
946.
The derivation of the space averaged Navier–Stokes equations for the large eddy simulation (LES) of turbulent incompressible flows introduces two groups of terms which do not depend only on the space averaged flow field variables: the divergence of the Reynolds stress tensor and commutation errors. Whereas the former is studied intensively in the literature, the latter terms are usually neglected. This note studies the asymptotic behaviour of these terms for the turbulent channel flow at a wall in the case that the commutation errors arise from the application of a non‐uniform box filter. To perform analytical calculations, the unknown flow field is modelled by a wall law (Reichardt law and 1/αth power law) for the mean velocity profile and highly oscillating functions model the turbulent fluctuations. The asymptotics show that near the wall, the commutation errors are at least as important as the divergence of the Reynolds stress tensor. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
947.
Algebraic dichotomies with an application to the stability of Riemann solutions of conservation laws
Xiao-Biao Lin 《Journal of Differential Equations》2009,247(11):2924-2965
Recently, there has been some interest on the stability of waves where the functions involved grow or decay at an algebraic rate m|x|. In this paper we define the so-called algebraic dichotomy that may aid in treating such problems. We discuss the basic properties of the algebraic dichotomy, methods of detecting it, and calculating the power of the weight function.We present several examples: (1) The Bessel equation. (2) The n-degree Fisher type equation. (3) Hyperbolic conservation laws in similarity coordinates. (4) A system of conservation laws with a Dafermos type viscous regularization. We show that the linearized system generates an analytic semigroup in the space of algebraic decay functions. This example motivates our work on algebraic dichotomies. 相似文献
948.
Conservation laws, hierarchy of dynamics and explicit integration of nonholonomic systems 总被引:1,自引:1,他引:0
This paper can be regarded as a continuation of our previous work [1, 2] on the hierarchy of the dynamical behavior of nonholonomic
systems. We consider different mechanical systems with nonholonomic constraints; in particular, we examine the existence of
tensor invariants (laws of conservation) and their connection with the behavior of a system. Considerable attention is given
to the possibility of conformally Hamiltonian representation of the equations of motion, which is mainly used for the integration
of the considered systems.
相似文献
949.
Michael Voit 《Journal of Theoretical Probability》2009,22(3):741-771
Bessel-type convolution algebras of measures on the matrix cones of positive semidefinite q×q-matrices over ?,?,? were introduced recently by Rösler. These convolutions depend on a continuous parameter, generate commutative hypergroups, and have Bessel functions of matrix argument as characters. In this paper, we study the algebraic structure of these hypergroups. In particular, the subhypergroups, quotients, and automorphisms are classified. The algebraic properties are partially related to the properties of random walks on these matrix Bessel hypergroups. In particular, known properties of Wishart distributions, which form Gaussian convolution semigroups on these hypergroups, are put into a new light. Moreover, limit theorems for random walks are presented. In particular, we obtain strong laws of large numbers and a central limit theorem with Wishart distributions as limits. 相似文献
950.
刘红兵 《数学的实践与认识》2007,37(19):140-143
经典错误逻辑研究的是错误传递、转化的规律,它为决策中避免错误,消除错误,减小错误的危害提供了新的方法.相似转化词是经典错误逻辑中的一个重要转化词,定义了相似转化词的概念,研究了这个转化词所具有的性质和规律. 相似文献