非各向同性的

Metallurgy School, UST Beijing, Beijing 100083, China）ABSTRACT The negative thermal expansion in some complex oxides has beenattributed to transverse thermal motion of A-O-M linkage composed of two-coordinate oxygenbridge bond, and the librationsand tilts of essentially rigid polyhedral blocks in openframework structure. The isotopic NTE materials have been finding moresubstantialapplications in composites and other relative technique fields.

氧化物材料负热膨胀机理邢献然摘要氧化物的负热膨胀性是由于在其开放式的骨架结构中，有二配位的桥氧键产生横向热运动，以及引起的多面体热摆动和耦合作用使非键合M-M1键距变短，导致单胞体积缩小；各向同性NTE氧化物在复合材料及其相关技术领域具有更广泛的应用价值。

Using the perturbation method and Stroh's formula, a nonideal crack, which is mathematically sharp and the opposing crack faces still have a gap in which a stiffless dielectric fills, the two-field problem is reduced to a standard Riemann-Hilbert problem. The internal electric field distribution is obtained by solving a singular integral equation, and then the full field both inside and outside the crack is obtained and the electro-mechanical intensity factors to the first order of accuracy are given.

采用摄动方法对裂尖理想尖锐而裂纹面又具有一定张开的非理想裂纹进行分析，裂隙内含有无刚度的各向同性电介质，利用Stroh公式，将二域问题化为标准的Riemann-Hilbert问题，裂隙内电场分布通过解一个奇异积分方程获得，从而得到裂纹内外的力电全场分布，进而给出一阶精度下的力电强度因子的表达式。

We extend the second order elastic tensor of Husdon's and turn it to a matrix which makes the calculation of second order perturbation much more concise. Then the azimuthally phase and group velocity formulas of plane wave propagation in horizontal plane are deduced according to Christoffel equation, and the azimuthally dependent velocities in dry and water saturated cracked medium are calculated.

而后，根据Christoffel方程推导了由各向同性背景介质中含两组非正交的垂直裂隙而形成的等效单斜各向异性介质中，在水平面内随方位变化的相速度和群速度的计算公式，并对干裂隙和饱和流体填充裂隙介质两种具体情况进行了计算。

But we don't care about Battlegrounds.

但我们并不在乎沙场中的显露。

Ah! don't mention it, the butcher's shop is a horror.

啊！不用提了。提到肉，真是糟透了。