差分系数

When we analyse rigid body with the theory of limit equilibrium, we do not obtain always reasonable maximal principle in physics, and the maximal value is the result of soil plasticity deformation.(2) Thoroughly commenting the typical method of slices from their satisfid equilibrium conditions, calculational parameter and their convergence, the thesis sortes the methods into four kinds. The first satisfies all kinds of equilibrium conditions, can obtain interslice force and the factor of safety.

2从满足的平衡条件、求解的参数及其解收敛性等，分析了各种常用极限平衡条分法，将其分为四类，第一类方法既满足力的平衡，也满足力矩平衡，能获得条间力和稳定系数的收敛解；第二类方法只满足一个方向力的平衡和力矩平衡，只能求得稳定系数；第三类方法既满足力的平衡，也满足力矩平衡，但不是严格的静定问题，解的收敛性差；第四类方法满足两个方向力的平衡，不满足力矩平衡，可求得稳定系数和条间力的大小，不能求得条间力方向。

Therefore,it is necessary to research diffusion equation for suspended sediment because it describes the sediment move process in the water body.The equation is a various coefficients second-order linear partial differential equa-tion,such equation under complex boundary condition is very difficult to get its analytical solution,while its numerical solution relative analytical solution is more easier and has the obvious superiority:simple,the computation convenience.but to get a kind of difference format which is good accuracy and stability is not easy.

泥沙扩散方程实际上是一个变系数的二阶线性偏微分方程，这样的方程在各种复杂边界条件下求解是十分困难的，求它的解析解在数学上存在着难以克服的障碍，无法求出其精确解，因此常用数值方法求它的近似解，相比较而言，数值方法有着明显的优势：即简单灵活、计算方便快捷，但要寻找一种精度高、稳定性好、计算方便的差分格式也并非易事。

Also the response amplitude will be changed with the initial conditions due to the nonlinear properties of the cables.Taking the bending stiffness, cable sag and cable inclination into consideration, the space vibration control of the cables using the visco-elastic dampers in cable-stayed bridges is investigated by joining the center difference method and the state space strategy. Both the maximum modal damping ration and the optimal damper size are obtained, then the practical suggestions are proposed for the design of the dampers. The space nonlinear vibration equations of the cable-damper system are derived, and anew hybrid method for solving the cable-damper system is presented by combing the Newmark method and Pseudo-force technology. According to the known properties of the cable-damper system, the nonlinear transient responses are analyzed under all kinds of excitations. Based on the transient response, the control effectiveness of the visco-elastic dampers is further demonstrated.

综合考虑了拉索抗弯刚度、垂度的影响，研究了粘弹性阻尼器对斜拉桥拉索的空间振动控制，联合中心差分方法及状态空间法，得出了拉索面内、外振动各阶模态可能达到的最大阻尼比及相应的最优阻尼器系数，并对斜拉桥拉索的阻尼器设计提出了参考建议：考虑拉索抗弯刚度、垂度及几何非线性，导出了索-阻尼器系统的空间振动非线性方程组，结合Newmark方法及伪力(Pseudo-Force)方法，创新地提出了求解非线性方程组的杂交方法，根据拉索-阻尼器系统的阻尼特性，在各种荷载作用下，对索-阻尼器系统的非线性瞬态振动响应进行了研究，从系统响应的角度更加直接地验证了阻尼器的控制效果。

In this paper the different methods ti find general term formulas of power series sum functions,by means of which coefficients are higher arithmetical of geometrical sequence .

利用差分法导出了求幂级数和函数的一个通项公式，用它能求出系数为高阶等差数列和高阶等比数列的幂级数∑∞n=0 anxn的和函数

Giving the more explicit boundary conditions and using Biconjugate gradients stabilized method to solve the linear algebra equation with large coefficient matrix, we get a fast algorithm of highprecision to calculate effectively electrical and magnetic fields in the whole space.

由于提出了简洁的边界条件，采用了解大型系数矩阵方程组的双共轭梯度稳定解法，所实现的三维交错采样有限差分数值模拟算法具有迭代收敛稳定、计算精度高、速度快等特点。

The research contents and main conclusions are as follows:1. The present thesis adopted one-dimension interior ballistic model, regarding the ballistic spatial core as the unsteady quasi one-dimension airflow containing the friction and heat exchange between airflow and tube wall, considering the boundary layer unsteady, nonstationary condensable current; and employed the MacCormack finite difference method to write the program.

本文的研究内容及结论主要体现在以下几个方面： 1、采用了一维内弹道模型，把弹后空间的核心流部分考虑为包含气流与身管管壁发生摩擦和热交换的不稳定准一维流，边界层考虑为不稳定、非定常可压缩流，用MacCormack有限差分方法求解，编制程序进行计算，较为准确的得到了复合材料身管固壁瞬态温度场分析内边界条件所需的气流温度和对流换热系数结果。

As a result, quantile regression method is better than other methods in both measuring systematic risk and nonsystematic risk.

在度量非系统性风险方面，主要应用于度量市场风险，并与利用GARCH模型度量VaR的方法和历史模拟方法进行比较，通过后验测试，结果表明，分位数回归在模拟VaR序列方面更为准确些；而在系统性风险度量方面，无论是根据平均绝对离差指标还是方差指标来看，结果发现利用分位数回归计算的系数要优于普通最小二乘估计和M估计。

A mathematical model of the direct chill casting process for superlight Mg-Li alloy (LA141) slab has been developed using the finite differential method. Thermal boundary conditions including primary and secondary cooling conditions, have been selected based on knowledges of the physical process and the literatures. The variations of heat transfer coefficient between slab and dummy block interface resulting from the deformation of the slab have been considered.

中文摘要：运用有限差分法，对超轻Mg-Li合金（LA141）板坯直冷连铸过程温度场进行数值模拟，根据实际过程的物理现象以及文献资料确定包括一冷区、二冷区在内的边界条件，并且考虑底模与铸坯之间随着铸坯的变形而引起的换热系数的变化。

In the second part, we make the study of the application of Z-transformation when we solve linear difference equation bearing constant coefficient and transmission function in pulsing system.

第2部分：&Z变换的应用&，主要通过上1章研究的Z－变换的逆变换和10个性质定理，研究了Z－变换在求解具有常系数的线性差分方程和脉冲系统的传递函数方面的应用。

The study of the mineralization degree ,water type and ion combination coefficient of the Pre-Tertiary formation water in Chaluhe fault depression,Yitong Basin,reveals that total mineralization degree of the water is relatively low,and NaHCO3 water type,while the formation water has obvious vertical mineralization zonation with a high metamorphic grade.

对伊通盆地岔路河断陷古近系地层水的矿化度、水型及变质系数、脱硫系数的研究表明，该区地层水总体为NaHCO3型水；总矿化度偏低；平面上，孤店斜坡的油气保存条件最差，梁家构造带最好，垂向上，具明显的垂向分带性，万昌组保存条件最差；变质程度高。

With Death guitarist Schuldiner adopting vocal duties, the band made a major impact on the scene.

随着死亡的吉他手Schuldiner接受主唱的职务，乐队在现实中树立了重要的影响。

But he could still end up breakfasting on Swiss-government issue muesli because all six are accused of nicking around 45 million pounds they should have paid to FIFA.

不过他最后仍有可能沦为瑞士政府&议事餐桌&上的一道早餐，因为这所有六个人都被指控把本应支付给国际足联的大约4500万英镑骗了个精光。