近似方法

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。

By study the method of approximate development of surface of revolution,the mathematiccal model of approximate development,precision analysis and error correction has been gained.

通过对不可展回转曲面近似展开方法的研究，得到了回转曲面近似展开、精度分析和误差矫正的数学模型。

Considering the characteristic and discipline of approximate computing over data stream model, we put forward a kind of Harr wavelet method on data stream sketch. This method improves the aggregate query effect on data stream model.

针对数据流计算模型的近似查询计算的特点和规律，研究与分析了数据流计算模型的基本特征，提出了一种基于数据流提纲的近似小波方法。

A fuzzy indiscernibility relation is changed into the indiscernibility relation by using a λ-cut in the rough approximation of decision classes, and an extension of VPRS method is proposed in which probabilistic rules are obtained from fuzzy decision tables.

为了从模糊近似空间中获取用于概率决策的规则，在决策类的粗糙近似中，通过应用λ-截集，将模糊不可分辨关系转化为等价关系，提出一种可从模糊决策表中获取概率规则的扩展变精度粗糙集方法。

Three approximate methods (called as scaling, rectangle and trapezia methods respectively) for performance analysis of orthogonal space-time block code with M-ary phase shift keying and M-ary quadrature amplitude modulation over flat Rayleigh fading channels are proposed, and their approximate performance expressions are given.

在平坦瑞利衰落信道下，提出了3种正交空时分组码在MPSK和MQAM调制下的近似性能分析方法(分别称为放缩法、矩形法和梯形法)，并给出其近似表达式。

The experimental results show the validness of the mechanism analyses.2. According to the generation mechanism of the leak acoustic signal, the characteristics of the leak acoustic signal are investigated. The auto correlation technology is adopted to descript the leak signal characteristics due to the ability to analyze the coherence of time series. A new procedure to identify the leak acoustic signal from the disturbed noises is proposed based on the conjunction of correlation and approximate entropy algorithm.3. The principle and application in leak location of the correlation and the adaptive filter techniques are introduced. The problems of the traditional leak location methods are analyzed.4. In order to establish the leak detection signal model, the leak acoustic propagation characteristics are investigated experimentally.

从泄漏声产生机理出发，分析了管道泄漏处湍流拟序结构与空泡间相互作用的机理，认为在该机理作用下，泄漏声信号产生过程具有&不可重复&的特征；由于相关函数具有分析时间序列拟序结构的能力，且近似熵从统计的角度区别时间过程的复杂性，因此，提出将信号相关分析和近似熵理论相结合的方法，提取泄漏声信号&不可重复&的特征，辨识管道泄漏故障发生；在实际检测现场，由于各种管内和管外固定声源噪声(如阀门噪声、工地施工噪声等)常导致泄漏误判和漏点定位错误，重点分析了管内固定噪声源的产生机理和特征，为复杂干扰环境下的泄漏辨识提供理论支持。

In order to testify the reliability of the approximate approach, the calculated value of volumetrically averaged energy dissipation rate based on the approximate approach are compared with the calculated results from an analytical equation derived on the thermodynamic laws and using the universally accepted equations for the friction factor.

为了检验能量耗散率近似算法的可靠性，将按近似算法计算得到的管内湍流体均能量耗散率与按热力学方法导出的解析式并采用公认的摩擦因子公式计算的体均能量耗散率进行了对比。

Basic quantities in stellar photographic photometry (in particular, colour index and "effective wavelength") are formulated according to the assumptions that: 1 stellar radiation may be represented by some black body equivalent and 2 within the limits of a single photometric "receiver", intensity-wavelength relationship of the radiation may be taken as linear.

本文对着当前的发展，综述了照相方法在恒星光度学中的地位。接着用两个简单的假设，即星体幅射的黑体近似和累积亮度范围中的直线近似，把恒星光度学中的基本定义(如有效波长、等光波长和色指数等)和主要问题(如空间红化，亮度效应等)表以公式。

Basic quantities in stellar photographic photometry (in particular, colour index and "effective wavelength") are formulated according to the assumptions that: 1 stellar radiation may be represented by some black body equivalent and 2 within the limits of a single photometric "receiver", intensity-wavelength relationship of the radiation may be taken as linear.

本文對着當前的發展，綜述了照相方法在恆星光度学中的地位。接着用兩個簡單的假设，即星体幅射的黑體近似和累積亮度範圍中的直线近似，把恆星光度学中的基本定義(如有效波長、等光波長和色指数等)和主要问题(如空間红化，亮度效应等)表以公式。

The caustics phenomena of electromagnetic wave propagation in concave reflector, the singularities of caustics, and the method of

40174032的一部分，得到如下结果：论文分析了利用Maslov方法求解非均匀介质中波动方程高频近似解的基本原理和求解过程，构造了介质系数只在一个方向变化时波动方程高频近似解的通用计算公式。

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。