广义Bayes诊断法

系统地阐述了Bayes的诊断思想,推广了多输入单输出诊断方法,对多输入多输出的诊断作出一次尝试,克服以往诊断的局限性,给出一种广泛应用的诊断方法,并通过仿真示例,表现出其可行性及有效性.     

On the boundary slip of fluid flow

For hundreds of years, in all the textbooks of classical fluid mechanics and lubrica- tion mechanics it is assumed that there was no wall slip (boundary slip) at a liquid-solid interface, i.e. no relative motion between liquid and solid at the interface. This is the no-slip boundary condition. It has been widely applied to engineering and experiments and to almost all the rheology or viscosity measurements of fluids. Rheology is one of the most important bases for fluid mechanics and lubricati…     

The use of apatite fission track thermochronology to constrain fault movements and sedimentary basin evolution in northeastern Brazil

An apatite fission track study of crystalline rocks underlying sedimentary basins in northeastern Brazil indicate that crustal blocks that occur on opposite sides of a geological fault experienced different thermal histories. Samples collected on the West block yielded corrected fission-track ages from 140 to 375 Ma, whereas samples collected on the East block yielded ages between 90 and 125 Ma. The thermal models suggest that each block experienced two cooling events separated by a heating event at different times. We concluded that the West block moved downward relative to the East block ca. 140 Ma ago, when sediments eroded from the East side were deposited on the West side. This process represents the early stage of sedimentary basin formation and the opening of the South Atlantic Ocean in the region. Downward and upward movements related to heating and cooling events of these crustal blocks at different periods until recent times are proposed.     

Role of strain-rate sensitivity in the crystal plasticity of hexagonal structures

In the first part of this paper the stress and strain-rate response of hexagonal crystal structures are examined when slip is viscoplastic according to a power law. The stress and strain-rate equi-potential surfaces are constructed and discussed as a function of the strain-rate sensitivity index m. The second part of this paper deals with the case of linear viscous slip; i.e., for the case when m is equal to one. A simple analytic solution is presented to obtain the deviatoric stress state for a given strain-rate. It is shown that the plastic spin is not zero for m = 1 in hexagonal crystal structures, contrary to the cubic case where the plastic spin vanishes. In addition, the rate of texture evolution in simple shear of a magnesium polycrystal is examined as a function of m.     

具有未知扰动的广义系统的故障检测

研究具有未知扰动的随机广义系统的故障检测问题,在合理的条件下,利用状态变换从原系统中分离出一个与未知扰动解耦的降阶子系统,构造了该随机子系统稳定的滤波器,给出了输出偏差量的统计特性,在此基础上,实现了系统故障的检测．     

基于无消相干子空间的量子避错码设计

针对量子系统的联合消相干模型,可以找到一些不受消相干错误影响的系统状态,这种状态被称为相干保持态,所有相干保持态构成的空间就称为无消相干子空间(decoherencefreesubspace,缩写为DFS).利用DFS的特性可以实现自动容错的量子避错码.首先提出一种DFS的定义,并且以定理的形式证明其他DFS的定义都是等价的.然后给出了DFS的存在性定理.最后利用群论的方法设计一种构造DFS的简单方法 关键词： 相干保持态 无消相干子空间 量子避错码 容错量子计算     

Solution of the planar Newtonian stick–slip problem with the singular function boundary integral method

A singular function boundary integral method (SFBIM) is proposed for solving biharmonic problems with boundary singularities. The method is applied to the Newtonian stick–slip flow problem. The streamfunction is approximated by the leading terms of the local asymptotic solution expansion which are also used to weight the governing biharmonic equation in the Galerkin sense. By means of the divergence theorem the discretized equations are reduced to boundary integrals. The Dirichlet boundary conditions are weakly enforced by means of Lagrange multipliers, the values of which are calculated together with the singular coefficients. The method converges very fast with the number of singular functions and the number of Lagrange multipliers, and accurate estimates of the leading singular coefficients are obtained. Comparisons with the analytical solution and results obtained with other numerical methods are also made. Copyright © 2005 John Wiley & Sons, Ltd.     

氧化锌纳米带中的面缺陷

面缺陷是纳米带中非常普遍和非常重要的一类缺陷。在有些情况下，面缺陷对于高表面能指数面的出现起着决定性的作用。同时。它们可以诱导纳米带沿着特殊的方向生长。面缺陷可以是孪晶或双晶，层错和由杂质原子聚集在特定原子面所形成的间隙原子层。在本文中。利用透射电子显微术，我们将介绍氧化锌纳米带中被发现的几种面缺陷。我们确认了两种孪晶／双晶结构，它们的孪晶面分别是（01^-13）和（^-2112）面。基面层错有I1和I2两种。在大尺寸的纳米带中，I1基面层错可以折叠到（2^110）面形成棱面层错。当少量的In离子掺入氧化锌纳米带后，我们发现伴随着杂质In在基面的聚集，形成了两种倒反畴界。     

Ondes adhérence–glissement–décollement sous contact unilatéral frottantStick–slip–separation waves in unilateral and frictional contact

A numerical study on the dynamic response of a mechanical system composed of two coaxial cylinders in relative rotation and unilateral contact with Coulomb friction is presented. This discussion complements the semi-analytical results on stick–slip waves given in Moirot, Nguyen, C. R. Acad. Sci. Paris Sér. IIb 328 (2000) 663–669, by some numerical simulations on the dynamic transition of the system from a given initial state to a surface wave. The case of stick–slip–separation waves is considered. To cite this article: A. Oueslati et al., C. R. Mecanique 331 (2003).     

基于小波变换的精密测试转台测角系统的故障诊断

针对精密测试转台测角系统的突变性故障、饱和故障和高频干扰故障,研究并提出了一种基于离散小波变换的故障特征提取方法。这种方法采用db4小波函数对测角系统激磁信号进行小波变换,将原始信号分解为近似信号和细节信号。根据分解得到第一层的细节信号,可以定位突变性故障和饱和故障。通过多层分解,确定近似信号和细节信号的最大幅值,根据信噪比大小可以确定是否存在高频干扰故障。实验结果显示,通过该方法可以实现对测角系统激磁电源故障准确的故障特征提取和定位,提高了精密测试转台的安全性和可靠性。