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131.
PENG Huan-Wu 《理论物理通讯》2004,(11)
Taking a hint from Dirac‘s large number hypothesis, we note the existence of cosmologically combined conservation laws that work cosmologically long time. We thus modify Einstein‘s theory of general relativity with fixed gravitation constant G to a theory for varying G, with a tensor term arising naturally from the derivatives or G in place of the cosmological constant term usually introduced ad hoc. The modified theory, when applied to cosmology, is consistent with Dirac‘s large number hypothesis, and gives a theoretical Hubble‘s relation not contradicting the observational data.For phenomena of duration and distance being short compared with those of the universe, our theory reduces to Einstein‘s theory with G being constant outside the gravitating matter, and thus also passes the crucial tests of Einstein‘s theory. 相似文献
132.
For calculating the predictive powers, we suggest an elegant expectation identity to directly calculate the expectations. We calculate the predictive powers of the hypotheses with a nonzero threshold for five different categories, which are non-sequential trials with classical power and Bayesian power, and sequential trials with hybrid predictions, Bayesian predictions, and classical predictions. Moreover, the calculations of the various predictive powers are illustrated through
three examples. Finally, when calculating the average success probability in \ncite{9}, it is tricky to find the predictive distribution for the predictive power, whereas, it is straightforward to utilize the expectation identity for the calculation. 相似文献
133.
134.
How much can randomness help computation? Motivated by this general question and by volume computation, one of the few instances where randomness provably helps, we analyze a notion of dispersion and connect it to asymptotic convex geometry. We obtain a nearly quadratic lower bound on the complexity of randomized volume algorithms for convex bodies in Rn (the current best algorithm has complexity roughly n4, conjectured to be n3). Our main tools, dispersion of random determinants and dispersion of the length of a random point from a convex body, are of independent interest and applicable more generally; in particular, the latter is closely related to the variance hypothesis from convex geometry. This geometric dispersion also leads to lower bounds for matrix problems and property testing. 相似文献
135.
A. Toutant M. Chandesris D. Jamet O. Lebaigue 《International Journal of Multiphase Flow》2009,35(12):1119-1129
In order to study and validate the jump conditions established in part 1, we realize a priori tests thanks to the data of a 3D Direct Numerical Simulation (DNS) of a strongly deformable bubble in a spatially decaying turbulence. The complex interactions between interface and turbulence are fully resolved. An explicit filtering of the DNS has been employed to evaluate the filtered quantities and to check the potential of the models for two-phase flows in the Interface and Subgrid Scales (ISS) modeling case proposed in part 1. The ISS concept is our proposal of a two-phase equivalent for the one-phase Large Eddy Simulation (LES) modeling case with sharp-interfaces. In this concept, bubbles remain bigger than the mesh size. Due to the impossibility to define a filter equivalent to the matched asymptotic expansions, we only test the modeling of the equivalent interface transport (the momentum jump conditions are not tested in this article, but will deserve additional results in a posteriori tests). Because the closure of the transport equation of the under-resolved discontinuous interface requires more modeling assumptions than the closure of the momentum equation, we think that the most relevant test has been done. The a priori tests realized show excellent agreement between the ISS models and the real contributions. 相似文献
136.
沪深股市收益率分布的时变性 总被引:16,自引:1,他引:15
本文对沪深股市收益率的统计特性进行了讨论 ,检验了收益率分布的非正态性和独立同分布性 .就其独立同分布假设被拒绝的原因从相关和不同分布两方面进行了详细的分析与研究 .结果表明 :沪深股市收益率存在一定的自相关性 ,但相关程度很弱 ,不足以用来作为解释对其独立同分布假设拒绝的理由 ;均值的时变性不显著 ,但方差是时变的 ,均值与时变的方差一起可作为对独立同分布假设拒绝的原因 . 相似文献
137.
We substantially apply the Li criterion for the Riemann hypothesis to hold. Based upon a series representation for the sequence
{λk}, which are certain logarithmic derivatives of the Riemann xi function evaluated at unity, we determine new bounds for relevant
Riemann zeta function sums and the sequence itself. We find that the Riemann hypothesis holds if certain conjectured properties
of a sequence ηj are valid. The constants ηj enter the Laurent expansion of the logarithmic derivative of the zeta function about s=1 and appear to have remarkable characteristics. On our conjecture, not only does the Riemann hypothesis follow, but an inequality governing the values λn and inequalities for the sums of reciprocal powers of the nontrivial zeros of the zeta function.
Mathematics Subject Classification (2000) 11M26. 相似文献
138.
A.M. Odlyzko 《Numerical Algorithms》2000,25(1-4):293-303
The Riemann hypothesis is equivalent to the conjecture that the de Bruijn–Newman constant satisfies 0. However, so far all the bounds that have been proved for go in the other direction, and provide support for the conjecture of Newman that 0. This paper shows how to improve previous lower bounds and prove that –2.710–9<. This can be done using a pair of zeros of the Riemann zeta function near zero number 1020 that are unusually close together. The new bound provides yet more evidence that the Riemann hypothesis, if true, is just barely true. 相似文献
139.
This paper provides an overview of the literature on statistical analysis of queueing systems. Topics discussed include: model identification, estimation, hypothesis testing and other related aspects. Not all of these statistical problems are covered in books on queueing theory or stochastic processes. The bibliography is not exhaustive, but comprehensive enough to provide sources from the literature. 相似文献
140.
We develop a unified theory for obtaining stochastic rearrangement inequalities and show how this theory may be applied in statistical contexts such as ranking problems, hypothesis testing, contamination models, and optimal assembly of systems. 相似文献