连续刚构铁路桥收缩徐变效应监测与分析

对连续刚构铁路桥箱梁温度场及桥梁线形进行长期、连续监测,通过主梁跨中下挠的理论与实测对比揭示了连续刚构铁路桥收缩徐变效应。对比了国内外常用收缩徐变估算模型,选择CEB-FIP徐变模型对黄河特大连续刚构桥进行了有限元分析。采用实测温度数据,以箱梁内测温度、外侧温度、顶底板温度梯度、左右侧温度梯度作为箱梁温度场的评判指标,对箱梁1年内的四季温度场分布进行分析。在基于相同温度场的条件下,通过理论值与实测值对比,发现分析成果与实测结果较吻合,说明混凝土的收缩徐变是引起连续刚构铁路桥跨中下挠的主要原因,对比结果还说明通过改善箱梁顶底板应力差能够改善收缩徐变长期效应。     

相对性原理与空间对称

本文分析了相对性原理与空间对称性的关系 ,指出物理规律不变性的破坏必然是时空空间的均匀性、对称性的破坏     

拆边法求最短路径

本文利用局部比较法 ,在图中定义子图、无效路径、以及可去边 .利用推导的有关定理 ,拆去可去边 ,利用最短路径相同的等价性 ,达到化简图 ,从而求出最短路径     

Entropy for frame bundle systems and Grassmann bundle systems induced by a diffeomorphism

A Liao hyperbolic diffeomorphism has equal measure entropy and topological entropy to that of its induced systems on frame bundles and Grassmann bundles. This solves a problem Liao posed in 1996 for Liao hyperbolic diffeomorphisms.     

气垫导轨在刚体转动惯量测定实验中的应用

本文介绍了一种测量刚体转动惯量的新方法。即把气垫导轨和刚体转动仪结合起来来测量刚体的转动惯量,使传统的气垫导轨实验和刚体转动惯量测定实验得以更新,提高了实验测量的精度,拓展了实验内容。     

滚动实验的另一种演示

介绍了另一种滚动演示实验,并对演示结果进行了理论分析和解释     

A rigid subspace of the real line whose square is a homogeneous subspace of the plane

Working in ZFC, we give an example as indicated in the title.

     

Variational Derivative for Buckling Loads of Beams and Frames

The finite-difference method is a numerical technique for obtaining approximate solutions to differential equations. The main objective of the present study is to give a new aspect to the finite-difference method by using a variational derivative. By applying this formulation, accurate values of the buckling loads of beams and frames with various end supports are obtained. The performance of this formulation is verified by comparison with numerical examples in the literature __________ Published in Prikladnaya Mekhanika, Vol. 41, No. 7, pp. 139–144, July 2005.     

Stable Ergodicity and Frame Flows

In this note we show that all diffeomorphisms close enough to the time-one map of the frame flow on certain negatively curved manifolds are ergodic. As a simple corollary we deduce that the frame flows are ergodic for all compact manifolds with curvature pinched sufficiently close to –1, thus providing results in the case of manifolds of dimension 7 or 8 which were missing from the results of Brin and Karcher.     

Geometry of an Accelerated Rotating Disk

We analyze the geometry of a rotating disk with a tangential acceleration in the framework of the theory of Special Relativity, using the kinematic linear differential system that verifies the relative position vector of time-like curves in a Fermi reference. A numerical integration of these equations for a generic initial value problem is made up and the results are compared with those obtained in other works.