查询词典 approximate method

The simulation results show that the proposed method can give approximate boundaries much closer to true boundaries than the method by unweighted LS-SVM.

仿真结果表明，采用本文方法比采用一般最小二乘支持向量机的方法所得的近似边界更接近精确边界。

An approximate worm wheel hobbing method is derived from the study of the engagement, module and pressure angle of worm and straight gear in the case of no worm wheel hob and then an adjustment method is determined for correct engagement between worm wheel and worm with standard cutting hob, which is more valuable in practice.

在没有涡轮滚刀的情况下，通过研究涡轮蜗杆与圆柱齿轮的啮合条件，以及涡轮蜗杆与圆柱齿轮间模数、压力角的关系，推导出一种使用标准齿轮滚刀近似加工蜗轮的方法。

Only with such characteristics, the movement equations can be expressed as matrices, and the idea of transforming the movement equations to the simplest form through a nonlinear transformation can be realized;(2) The form of Zi =Yi + YTH2i Y + Y7H3i Y(2)+ Y(2)T H4i Y(2)+ YTH5i Y(3) is adhibited in the nonlinear transformation, so that the multivalued problem caused by the nonlinear transformation is avoided, and the higher order transformation can be taken next;(3) The fourth order nonlinear transformation matrices H21,H31,H41 and H51 are derived, by which the original movement equations of electric power system is transformed to Jodan form in Z space;(4) By use of the fourth order nonlinear transformation, the approximate expression of the stability boundary is obtained, in Z space it is Z1= 0,in Y space it is Y1 + YTH21 Y + YTH31 Y(2)-i- Y(2) TH41 Y(2)+YTH51 Y(3)= 0;(5) The criterion used in this paper to judge whether the system critical unstable is simple and quick;(6) The method used in this paper is a direct method, and no need to construct an energy function.

正是由 于电力系统的运动方程具有这样的特性，才能写成矩阵的形式，通过非线性变换将电力系统的运动方程变换为最简单的线性形式的思想才能得以实现；（2）将通常运用于电力系统暂态稳定性分析的Normal Form变换的形式由 Yi＝ Zi＋ ZTh2riZ变形为 Zi＝ Yi＋YTH2iY＋YTH3iY（2）＋Y（2）TH4iY（2）＋YTH5iY（3），从而使得在对持续故障轨线实施同样的非线性变换以确定临界切除时间时，避免了非线性变换带来的多值性的问题，而只有在没有多值性问题的困扰下，才能采用较高阶的变换：（3）推导出了将原始电力系统系统的运动方程变换到Z空间的约当形式的非线性变换矩阵H21、H31、H41、HS1：（4）在运用四阶了「线性变换的情况下，给出了受扰动后系统的稳定边界的近似的解析表达，在Z空间为Z1=0，在y空间为： Y1+YTH21Y+YTH31Y(2)+Y(2)TH41Y(2)+YTH51Y(3)=0 （5）确定临界失稳的判据简单、快捷：对于一个复杂的电力系统，其稳定边界是相当复杂的一个高维曲面，即便是已知系统稳定边界的解析表达，要求出系统持续故障轨线何时与这一高维曲面相交，在数学上几乎是不可能实现的。

Simultaneously, the exports of ionization rate and nonionzed concentration are set up as a powerful tool for studying thoroughly the freeze-out effect. dN〓/dp and dN〓/dn are neglected in the linearized equation system of the iteration methods of Newton and Gummel, due to having lower 15 orders or more than dN〓/dn and dN〓/dp, thus the computing effort is cut down with no effect on precision. A new cut-off technique is adopted to accelerate the convergence speed, about twice reduced for Newton iteration method and six times or so for Gummel iteration method. The approximate formulae of Fermi-Dirac statistics are also put forward with simpler form and higher precision. 3. A term dependent on time is added to the electron and hole current succession equations respectively. It is only this model that conservation of charge in transient analysis and alternating small-signal analysis at low temperature can be kept by. 4. The performance of SE-PISCES is explained by the simulation example of PISCES-2B, diode.

研究了低温半导体器件模拟的数值方法：对载流子浓度进行了新的归一化；编制了不考虑掺杂所引进的内建电场时的电离率计算程序；由于低温杂质电离率随偏压状态而变化，为此编制了每次求解迭代时的电离浓度计算程序，并将其插入到求解迭代程序中；同时，设置了杂质电离率和未电离杂质浓度的出口点，为更深入地研究冻析效应提供了有力工具；在Newton迭代法和Gummel迭代法的线性化方程组中忽略了dN〓/dp、dN〓/dn，是因为它们比dN〓/dn、dN〓/dp低15个数量级以上，这样减小了计算量又不影响模拟精度；对Newton迭代法和Gummel迭代法采取了新的截断技术，提高了收敛速度，Newton法迭代法和两次左右，Gummel法减少六次左右；给出了表达式更简单而精度更高的Fermi-Dirac积分近似计算公式。

On the approximate uncorrelation property of DWT coefficients of LMSV process in the same scale and different scales, first the quasi maximum likelihood estimation method of parameters and the estimation method of volatility process of LMSV model are presented.

根据小波变换可将过程分解到不同的尺度上以及LMSV过程同一尺度下和不同尺度下DWT系数的近似不相关性，提出了建立局部似然函数的方法，又根据DWT系数和MODWT系数之间的关系，将局部似然函数表示为模型参数和局部小波方差估计的形式，并用该方法对中国股市收益进行了时变LMSV模型参数的估计。

This paper applies approximate equation to describe the characteristic curve of an axial flow fan, for the purpose of determining its working system,and is intended to apply the equation method for enlarging the extent of the analy-tical method, commonly used for determining the working system of axial flow fan and the ventilating syetem of a mine.

本文应用近似方程来描叙轴流式扇风机的特性曲线，其目的要确定矿井轴流式扇风机的工作制度，并且企图使扇风机工作制度与矿井通风制度上应用方程法来扩大分析法的范围。

The exact solution for unlimited long strip plane membrane is obtained by analytical method,and discussed with the approximate solution by energy method.

在垂直于板的载荷作用下，平衡方程为σx2wx2+σy2wy2+2τ2wxy=qh[2]。这个方程虽然是在变形后建立的，但载荷的大小和方向是不变的。

The VCL method and the displacement method are used to calculate the Stress Intensity Factors of semi-elliptical surface crack at the root of pipe screws, on the basis of which a simplified calculating model for screws contact is put forward so as to analyse the fracture intensity for oil drill pipe screw coupling. For the semi-elliptical surface crack with different shape and deep ratio at the root of female and male screws and the corner of male flange, the SIF has been studied systemically under inter-pressure, tension, bend and torsion loads and the approximate formulas encluding the structure parameters of oil drill pipe screw coupling, deep ratio and the shape parameters of surface crack are developed.

对工程实际中的多种石油钻杆接头螺纹连接件，就公螺纹齿根、母螺纹齿根、公螺纹台阶转角处存在的不同形状、不同厚度比的半椭圆表面裂纹，在拉伸、内压、弯曲、扭转多种载荷作用下的应力强度因子作了系统研究，在大量有限元计算基础上，建立了包含接头结构参数、裂纹形状、厚度比在内的近似计算公式。

First, the scattering parameters of PT are transformed in to Y-parameters and equivalent "p" circuit model could be established. Second, vector fitting method is used to approximate admittances of equivalent "p" circuit model by rational functions. At last, a circuit synthesis method for rational functions is applied to build circuit model.

该方法首先将测量得到的互感器的散射参数转化为导纳参数并构建互感器的p形等值电路；然后，应用矢量匹配法对p形等值电路的导纳参数进行有理函数逼近获得它们部分分式和形式的频域表达式；最后采用电路综合方法构建出导纳元件的等值电路。

Nonlinear partial differential dynamic equations of bending vibration of a tilting stepped drive shaft with two supports were built under non-inertia movement coordinate system by theorem of the motion of mass center and Heaviside function. According to the condition of equal displacement in an adjoining plane of the shaft, an equivalent shaft and its equation were obtained. A motion equation of the equivalent shaft was obtained by method of Galerkin. An approximate steady-state solution of the main resonance was obtained by method of multiple scales. The influence factors, motion stability, amplitude jump of main resonance of a stepped drive shaft and so on were analyzed.

用质心运动定理、Heaviside函数建立了非惯性系下倾料两端支承阶梯传动轴的非线性弯曲振动偏微分动力学方程，并根据相邻轴段的衔接面处位移相等的条件，得到阶梯轴的当量轴及其动力学方程；用Galerkin法得到当量轴的弯曲运动方程，用多尺度法求得稳态下当量轴的主共振的一次近似定常解，分析了影响阶梯传动轴主共振的因素、运动稳定性、振幅突变性等。

The split between the two groups can hardly be papered over.

这两个团体间的分歧难以掩饰。

This approach not only encourages a greater number of responses, but minimizes the likelihood of stale groupthink.

这种做法不仅鼓励了更多的反应，而且减少跟风的可能性。