查询词典 approximate method

A variational method with differential forms gives better precision for numerical solution of transport critical problem based on spherical geometry, and its computation seems simple than other approximate methods.

对于球几何问题，讨论了一种基于微分方程的变分形式求解方法，数值计算显示达到了较满意的精度，而且计算过程比起其他近似方法要简单

Secondly, method of Taylor series is used to approximate the slow manifold and the O approximation of the slow manifold is given; slow dynamics such as saddle node bifurcation which has been proven to be the same as that for the full system is analyzed; at the same time, fast dynamics including bifurcation conditions and domain of attractor of the stable equilibrium are also analyzed; the attracting region which consists of the stable manifold of the unstable equilibrium and stable equilibrium is given; we found that when the inner flux decay increases, the domain of attractor is enlarged.

首先，给出了电力系统SMIB模型的时间尺度分解，得到标准的奇异摄动模型；其次，利用幂级数方法，给出了慢流形的O近似M〓，分析了在慢流形M〓上的慢动态，得到了慢子系统的鞍结分支值，并证明此分支值与原系统的鞍结分支值相同；分析了快子系统的平衡点和全局分支的存在条件，给出由不稳定平衡点的稳定流形与稳定平衡点形成的吸引域；并研究内部电压对稳定域的影响，发现稳定域随内部电压增加而扩大；最后给出整个系统的稳定平衡点的近似吸引域。

Aimed at the problem of choosing the initial value when the Newton method is used to compute the controlling unstable equilibrium point, a practical and rigorous solving scheme was presented: by identifying the controlling load bus of the given fault, and using the Thevenin equivalent circuit to represent the rest of the system at the state of the post disturbance stable equilibrium point, using the steady equivalent circuit to represent the induction motor in composite load, and then using the torque characteristics of induction motor, a point near the CUEP is gained to be the initial value. The second order normal forms was used to approximate the stable manifold of CUEP, and the local approximating boundary of the region of attraction of the post disturbance stable equilibrium point was gained. Then just by simulating the state of the system at the fault clearing time, the transient voltage stability of the system could be determined.

针对采用牛顿法求取故障后系统主导不稳定平衡点(controlling unstable equilibrium point，CUEP)存在的初值选取难题，提出一种实用但不失严谨的解决方案：通过识别给定故障的主导负荷母线，对主导负荷母线以外系统由故障后稳定平衡点处的状态进行戴维南等值，对负荷中感应电动机部分采用其稳态等值电路，再由感应电动机的转矩特性求得CUEP附近的一个点作为近似的CUEP，以此为迭代初值可靠求得CUEP；采用二阶正规型来近似CUEP的稳定流形的方法求得近似的局部吸引域边界；由仿真得到故障清除时刻系统的状态并根据该状态是否位于吸引域内判断系统的暂态电压稳定性。

Based on statistical learning theory and optimization theory,unconstrained optimization models for support vector machines are built,and an approximate algorithm-maximum entropy method is given.

本文方法特别易于计算机实现，数值实验结果表明了模型和算法的可行性和有效性。1引言近年来，在V.V apn ik的统计学习理论[1，2]基础上发展起来的支持向量机(Support V ector M ach ine，SVM)正成为机器学习领域中新的研究热点[3，4，5]。

Therefore, basic methodologies for stochastic seismic and filtering responses of nonlinear structure are studied, the approximate solution methodologies and their practical applications are investigated in the dissertation employing equivalent linearization and moment equations method based on FPK equations and Ito stochastic differential equations. The research works are mainly concerned with the following aspects:Firstly, the differential expression of bilinear hysteretic is studied and a new differential expression is developed, then they are demonstrated.

因此，本文基于FPK方程和伊藤随机微分方程，研究了滞后结构物的随机地震反应和随机滤波问题的基本方法，并利用等效线性化法和矩方程法，研究了非线性结构随机地震反应分析和随机滤波分析的近似解法及它们的工程应用。

The inventory cost is a primary component of the supply chain cost, and the method for multi-echelon inventory optimization and control must be adopted for the sake of the entire supply chain optimization and control, t present, papers on multi-echelon inventory systems have solved some problems, but they still have limitations. Firstly, they assumed that leadtime are constants. In practice, as the unknowable incidents exist in production, transportation and distribution processes, leadtime usually are uncertain. Secondly, there exist the hypotheses of totally back orders or completely lost sales under the condition of stockout in most literatures. Thirdly, the existing two-echelon inventory approximate model optimum always fixes one variable in the inventory strategy, and then seeks the optimal in the remained parameters, which makes the result can not be the best outcome.

目前有关两级库存优化控制的研究文献大多是假设提前期为常数的基础上建立模型，然而现实中由于供应链上各节点的库存不确定性以及运输、生产、交货等环节的不可预知性，使得提前期在多数情况下是不确定的；而且大部分文献都是假设缺货情况下要么完全延迟交货，要么完全损失销售，很少有考虑部分损失销售情况下库存优化控制的；另外，现有的两级库存近似模型的优化大都是固定一个库存策略中的变量，对余下变量寻优，其优化结果不可能是最优结果。

Any order approximate solution of the equation was presented, and its convergence was mathematically proved by the successive approximation method.

采用逐次逼近法，求得任意阶近似解，并证明解的收敛性。

In fact, by the conventional method, just an approximate tangent linear model can be derived.

用传统方法得到的实质上是近似的切线性模型。

In this part, a new method, using tensor algebra, is developed to yield any order approximate analytical solution of a universal nonlinear dynamic system equation, which is abstracted from a large class of nonlinear dynamic systems in many different disciplines.

该篇采用张量代数，首次用严格的分析方法获得了适合不同学科的、普遍的非线性动力系统方程任意阶近似解析解。

This principle initiated a new method on the mechanism design of approximate constant speed ratio transmission.

此原理开创了近似等速比传动机构设计的新方法。

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。