半时

In this paper, based on an optimum difference operator for spatial differential given by Holberg, an optimum difference method of modeling crosswell elastic wavefield is put forward, which adopts the staggered-grid technique and calculates the wavefield at different grid points. When the half length of optimum difference operator is taken as four to six points, the required number of grid points per wavelength equals to three, crosshole elastic wavefield numerical modeling can attain satisfied accuracy.

本文以Holberg提出的一种空间微分的最佳差分算子为基础，采用交错网格技术，提出了一种模拟井间弹性波场的最佳差分法，该方法能在大空间网格点上得到精确的波场值，当最佳差分算子的半长度取4～6个点，每个波长只采3个样点时，井间弹性波场的模拟就可以得到满意的精度，其计算速度比常规有限差分法至少快一个数量级。

The main results of the investigation are as following:(1) Some important criteria for the design of multi-layer structure are acquired: the ratio of the layer thickness to the contact diameter should be controlled to a value about 0.8; increasing the number of the gradient layers and elasticity modulus of the top layer would benefit to the yield strength and the stress status at the interface.（2）By means of molecular dynamics simulations for a indentation and sliding process, it is discovered that dislocations of 45 direction to the surface occur in the surfaces layer, which is correspond to the direction of the plastic flows observed in the macroscopic continuous medium. The irreversible deformation caused by the dislocation and the atom piles at the surface are responsible for the irreversibility of the force response. They are also the main factors for the friction generation. The temperature and the indentation velocity have significant effects on the deformation behaviors of the material of the surface layer. The yield strength would increase obviously if the indentation velocity is greater than 10 m/s.（3）A method to evaluate the fracture toughness of coating by estimating the crack-density functionβof a Wicker''s indentation was proposed. Meanwhile a new surface treatment technology was developed using non-equilibrium plasma.（4）A MD-FE hybrid method and corresponding software was developed to analysis the tribological behaviors for multiplayer system.

研究主要内容和结果有：（1）得到指导梯度膜设计的几个准则：控制膜层厚度与接触半径比在0.8左右为宜；适当增加梯度层层数和顶层弹性模量，有利于提高抗屈服能力和改善界面处的应力状态；（2）通过对嵌入和滑动摩擦过程的分子动力学模拟，发现表层产生一个与宏观连续介质的塑性流动方向观测一致的45 方向位错；位错造成的不可逆变形和表面的原子堆积，是力的响应不可逆性的原因，也是构成摩擦力的主要因素；温度和嵌入速度对材料变形特性有显著的影响，当嵌入速度大于10 m/s时，屈服强度明显增加；（3）提出压痕裂纹密度系数β半定量判定膜层断裂韧性的方法；并开发出表面强化新工艺；（4）开发出分析表面摩擦学特性的MD-FE复合模拟方法和相应模拟软件。

An advanced numerical analysis indicates that two coaxial hyperbolic secant beams, provided that they satisfy the functional relations of FWHM with amplitudes of this type of PVSS, will be very close to solitons when they propagate in PV crystals.

进一步的数值模拟结果表明，当入射双曲正割光束满足复色光伏孤子半高宽与中心光强的关系时，双曲正割光束在晶体中的传播就非常接近孤子，表明复色光伏孤子对于小的微扰是稳定的。

There is the Cauchy problem of hyperbolic system with weak damping in Chapter4. In the space of dimension N=1,3, exploiting the semigroup method, the global existence and the decay behavior of the solution with small initial data to problem (about problem with small initial data) is put forward.

当空间维数N=1，3和初值充分小时，利用半群理论得到问题整体解的存在性，并对于整体解给出一致衰减估计；当空间维数N=1 时，利用试验函数方法讨论解在有限时刻爆破的条件。

While Greece teeters, one of its eurozone peers on the Iberian Peninsula is feeling a tad wobbly too.

当希腊步履蹒跚时，在伊比利亚半岛上，它的一个欧元区同盟也感到些许的摇晃。

Her words were inward and indistinct when she was in a state of half unconsciousness .

她处于半昏迷状态时，她说话的声音低沉，模糊不清。

Her words were inward and indistinct when she was in a state of half unconsciousness.

"她处于半昏迷状态时，她说话的声音低沉，模糊不清。"内心的；心灵上的

In regard of the problems on semi plane, when the calculation of its numerical value proceeds, the calculation accuracy will come under influence if the effectiveness of the infinite far place on the nearby sites are not considered.

对于半平面问题，在进行数值计算时，如果不考虑无限远处对近场的影响，则计算精度会受到一定的影响。

The Green functions of the vertical and horizontal force applied at interior of the saturated half space are established in the paper by using integral transform method.

应用积分变换方法得出了半空间饱和土内部作用垂直和水平载荷时的格林函数，为结构和饱和土动力相互作用的研究提供了工具。

Using the semiclassical rescattering model, we have studied the effect of molecular internuclear distance on non-sequential double ionization.

利用半经典再散射模型，我们研究了激光强度在一定范围内时分子核间距对非时序双电离过程的影响。

It has been put forward that there exists single Ball point and double Ball points on the symmetrical connecting-rod curves of equilateral mechanisms.

从鲍尔点的形成原理出发，分析对称连杆曲线上鲍尔点的产生条件，提出等边机构的对称连杆曲线上有单鲍尔点和双鲍尔点。

The factory affiliated to the Group primarily manufactures multiple-purpose pincers, baking kits, knives, scissors, kitchenware, gardening tools and beauty care kits as well as other hardware tools, the annual production value of which reaches US$ 30 million dollars.

集团所属工厂主要生产多用钳、烤具、刀具、剪刀、厨具、花园工具、美容套等五金产品，年生产总值3000万美元，产品价廉物美、选料上乘、质量保证，深受国内外客户的青睐