近似法

Methods Ionization chamber and film dosimetry methods were used to compare the angular dose distribution, point source approximation in the area close to the source,the coincidence of inverse square law of source strength and the scatter and attenuation in water medium,of a cylindrical, miniature 192 Ir source and "the ideal point source".

用电离室法与胶片法实测国产192Ir放射源空间剂量角分布、点源的近似性与源强反平方定律的符合性以及水介质散射与衰减特性，并与点源剂量分布特性比较。

To study numerical solution of the linear equations,the article presents direct method ,Jacobi iterate method and Gauss-seidel iterate method to approximately calculate,and has given its process in MATLAB.

为研究线性方程组的数值解，文章用直接解法、雅可比迭代法、高斯-赛德尔迭代法进行了近似计算，并给出在MATLAB中计算的程序。

Results show that radial basis function and point interpolation methods possess Kronecker Delta function property, but the robustness is poor in some cases; the MLS approximation function does not possess Kronecker Delta function property, but it has good robustness. Differences among the three discretization schemes of meshless method are as follows:the collocation method requires no numerical integration and very little computational time while its robustness is poor; Galerkin method is not a truly meshless method due to the background meshes required for integration; the Petrov-Galerkin method is a truly meshless method and need numerical integration in each sub-domain, so it needs more computational time.

分析结果显示：径向基函数和点插值法均具有d 函数属性，但计算稳定性差；移动最小二乘近似函数不具有d 函数属性，但计算比较稳定；无网格方法中的3种离散方法不同之处在于：配点法不需要积分，计算量小，计算稳定性差；Galerkin方法需要借助背景网格进行积分，它不是真正的无网格方法；Petrov-Galerkin方法，是一种真正的无网格方法，它需要对每个子域进行积分，计算工作量较大。

In combination with the crushed rock slope as an example, the allocation of an anchorage force on longitudinal beams and transverse beams is calculated by adopting the distribution coefficient law of the nodal form at first. Then the internal forces of the lattice beam are calculated respectively through the software on the basis of Winkler elastic foundation model and the semi-infinite foundation model, and then compared with the internal forces which are based on simplified foundation pressure calculation. The active pressure of rock is calculated approximately by Ranking soil pressure theory in the working stage. Sequentially, the reinforcing bars are disposed by two-stage's averagely calculated values.

以破碎岩质边坡为例，采用节点荷载分配法计算了锚索锚固力在格构梁纵、横梁之间的分配比率，然后基于Winkler弹性地基模型和弹性半空间地基模型分别计算格构梁在张拉阶段的内力，并与采用简化的地基反力计算值对比；采用朗肯土压力理论近似计算在工作阶段主动岩体压力，将地梁视为在线性分布力作用下倒置于坡面上的连续梁，按力矩分配法计算地梁内力，取两阶段计算平均值进行配筋。

Firstly, the function sinx that appears in the simple pendulum equation is replaced with a polynomial of degree 3 using Maclaurin series expansion and Chebyshev polynomial approximation. Subsequently, the resulting equation which is a Duffing type equation is approximately solved with combing Newton's method and the harmonic balance method.

首先，利用Maclaurin展开和Chebyshev多项式加速技术将单摆振动方程中的正弦型恢复力用三次多项式近似代替，得到一个Duffing型方程；然后，将牛顿法与谐波平衡法结合起来建立Duffing方程的解析逼近周期及周期解，从而给出单摆振动的解析逼近解。

In order to achieve accurate solutions of ill-conditioned GPS equations with a few observational epochs, the ill-conditioned normal equations of GPS rapid positioning was transformed as a function optimization problem. Then genetic algorithm was used to calculate parameter solutions, which avoided the inversion of coefficient matrix of normal equations.

为准确解算仅有少数几个历元的GPS载波相位观测数据的病态定位方程，将GPS快速定位的病态法方程求解问题转化为一个函数优化问题，应用遗传算法求解病态方程，避免了法方程的求逆运算，从而可以得到参数的近似最优解。

After probable damage location through MSECR, the method based on the sensitivity of orthogonality conditions gives good predictions of damage. This method overcomes the natural defect of the concept first order approximation of the ordinary sensitivity analysis method.

为克服灵敏度分析法一阶近似的本质缺陷，基于正交条件灵敏度分析法，利用MSECR对结构的损伤进行粗略定位后，给出了准确的识别结果，但这种方法的缺点是需要完备的实测振型。

We must seek two main approximation methods of solution , the variation method and perturbation theory

我们必须寻求两个主要的近似解法、变分法和微扰法。

First backward simulation was made by using population parameter method to quickly get an approximate workblank,and then forward simulation was made by using incremental method to modify the workblank outline for the purpose of getting comparatively accurate outline dimension.

介绍了一种用于冲压毛坯设计的新方法——基于正、反向模拟的毛坯外形设计技术，即先用全量法进行反向模拟，快速得出近似的坯料，再用增量法进行正向模拟修正毛坯的外轮廓，从而得到比较精确的坯料尺寸。

In chapter 4, some vector mathematical definitions are first given to position tolerance zones; second, the principle of variation geometry is introduced, and the mathematical foundation of automatic generation of a approximate linear equation of tolerance design function by variation geometry is first proven; tangent method and two-point slope method based variation geometry are main studied.

第四章首先对一些位置公差带给出了矢量化的数学定义；然后介绍了变动几何的原理，首次论证了变动几何能产生近似线性公差设计函数的数学依据，并着重研究了基于变动几何的切线法和二点斜率法。

According to the clear water experiment, aeration performance of the new equipment is good with high total oxygen transfer coefficient and oxygen utilization ratio.

曝气设备的动力效率在叶轮转速为120rpm～150rpm时取得最大值，此时氧利用率和充氧能力也具有较高值。

The environmental stability of that world - including its crushing pressures and icy darkness - means that some of its most famous inhabitants have survived for eons as evolutionary throwbacks, their bodies undergoing little change.

稳定的海底环境─包括能把人压扁的压力和冰冷的黑暗─意谓海底某些最知名的栖居生物已以演化返祖的样态活了万世，形体几无变化。