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981.
We consider chains whose transition probabilities depend on the whole past, with summable continuity rates. We show that
Ornstein's -distance between one such chain and its canonical Markov approximations of different orders is at worst proportional to the
continuity rate of the chain. The result generalizes previous bounds obtained by X. Bressaud and ourselves, while relying
on a similar coupling argument.
Received: 9 April 2002 相似文献
982.
We describe a linear-time algorithm for solving the molecular distance geometry problem with exact distances between all pairs of atoms. This problem needs to be solved in every iteration of general distance geometry algorithms for protein modeling such as the EMBED algorithm by Crippen and Havel (Distance Geometry and Molecular Conformation, Wiley, 1988). However, previous approaches to the problem rely on decomposing an distance matrix or minimizing an error function and require O(n2) to O(3) floating point operations. The linear-time algorithm will provide a much more efficient approach to the problem, especially in large-scale applications. It exploits the problem structure and hence is able to identify infeasible data more easily as well. 相似文献
983.
Andrei Yu. Zaitsev 《Annales de l'Institut Henri Poincaré (B) Probabilités et Statistiques》2002,38(6):1071
Estimates of the rate of approximation in a de-Poissonization lemma of Beirlant and Mason [1] is obtained for the case where the distribution satisfy a quantitative condition of existence of exponential moments introduced in [6]. 相似文献
984.
985.
986.
Feng‐Ling Liu Ling Peng Jian‐Xia Zhao Shou‐Qing Wang 《International journal of quantum chemistry》2005,103(2):167-175
Structures, energies, and vibrational frequencies have been calculated for two C50H40 isomers with three dodecahedrane cages sharing two pentagons at the B3LYP/6‐31G* level of theory. Thus, two C50H40 isomers have the form of coplanar tri‐dodecahedrane‐cage molecules. The symmetry of one isomer is D5d and that of another is C2V. Heats of formation and vertical ionization energies for two C50H40 isomers have been estimated in this study. Heats of formation as well as vibrational analysis indicate that two C50H40 isomers enjoy sufficient stability to allow for its experimental preparation. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005 相似文献
987.
988.
基于旋转磁场测距(RMRS)的基本理论,借助ANSYS有限元分析软件,研究了金属套管条件下双水平井电磁测距径向距离计算方法。首先建立SAGD双水平井RMRS井下传播模型,通过设定单元属性、划分网格、加载边界条件等对模型进行求解;然后研究套管厚度、直径、相对磁导率等对双水平电磁测距系统中磁场轴向分量的影响;最后利用实验室现有的旋转磁场测距模拟装置对仿真结果进行了验证。研究结果表明:随着套管厚度、直径、相对磁导率的增加,探管接收到的磁感应强度会逐渐减小,但双水平井径向间距计算仍可采用均匀介质中的理论测距导向计算方法。此结论可为套管的选取、磁导向仪器的研究及测量资料解释提供理论参考。 相似文献
989.
Let G = (V, E) be a simple connected graph with vertex set V and edge set E. The Wiener index W(G) of G is the sum of distances between all pairs of vertices in G, i.e.,
, where d
G
(u, v) is the distance between vertices u and v in G. In this paper, we first give a new formula for calculating the Wiener index of an (n,n)-graph according its structure, and
then characterize the (n,n)-graphs with the first three smallest and largest Wiener indices by this formula. 相似文献
990.
Jalilian MR Zahedi-Tabrizi M 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2008,70(5):1020-1024
With the purpose of finding predominant tautomer among five possible isomers of 3-amino-1,2,4-triazin-5-one and to refine some unreasonable structural parameters previously reported from X-ray diffraction measurements, a series of ab initio calculations were carried out. In agreement with previous results, our calculations show that 3-amino-1,2,4-triazin-5(2H)-one tautomer is the most stable one. Concerning the predominant tautomer, comparisons were made between structural parameters calculated and those obtained by X-ray crystallographic analysis. The structural geometry of the main skeleton of the molecule calculated by the B3LYP/6-311++G** density functional method are generally in good agreement with the experimental values, and those predicted by Pauling's method. Bond distance values calculated are in excellent agreement with the conventionally accepted bond lengths in similar molecules. All bond distances, bond angles, dihedral angles, dipole moments and rotational constants are presented. 相似文献