近似积分

The major implementations of the developed model include: Pseudo-spectral and finite-difference schemes are employed to approximate the spatial-differential operators in the horizontal and vertical directions, respectively. A second-order Runge-Kutta method is adopted to integrate in time for the velocity field and the free-surface elevation. The solenoidal condition of the velocity field is satisfied by solving the transformed pressure Poisson equation. A modified secant method is used to accelerate the iterative solution of the non-separable Poisson equation.

模式的主要数值方法包括：分别以拟频谱法以及二阶有限差分法近似控制方程与边界条件中的水平与垂直导数；以二阶Runge-Kutta法进行非稳态的自由液面位移与流场速度的时间积分；利用改良式割线叠代法求解计算区间中不可分离的压力Poisson方程式，以满足不可压缩流条件。

For experimental setup to calibrate spectral radiance by applying a diffuse plane, the measured spectral radiance can be obtained through integral of spectral radiation flux entering the spectrometer.

在利用漫反射板标定光谱辐亮度的实验装置中，标准灯完全可以近似为点光源。通过对进入光谱仪的辐射通量的数值积分，可以对应求出仪器的实测光谱辐亮度的计算公式。

It was supposed that the dynamic moving process of the stock price and the return was driven by Geometry Brownian Motion and the lognormal distribution respectively. Takinginto account the riskneutral environment, we got a closedform analytical formula for deferred arithmetic asian options by the method of Taylor expansion of the stochastic integral formula within the terminal payoff. Furthermore, with the series definition of the definite integral, we transferred the continuous problem into a discrete one which is simpleenough to figure out. Meanwhile we tested the accuracy of the formula with the Monte Carlo simulation as a benchmark and the result shows that the formula can be utilized to price the related financial derivatives.

在标的价格服从几何布朗运动、收益服从对数正态分布的前提下，通过风险中性定价原理，对到期损益中的随机积分进行任意次Taylor近似，并由级数定义将此连续问题离散化，给出了延期算术平均亚式期权封闭形式的解析定价公式，并与Monte Carlo模拟得到的价格作为标尺对得到的公式进行精确性检验，结果表明，所得公式可以应用到金融实务中对此类衍生品定价中。

The arithmetic advanced people who had studied all knows , the integral concept is four key: Carve up similar summation taking a limit.

学习过高等算术的人都知道，定积分的概念是四个关键：分割——近似——求和——取极限。

Besides,the trapezoidal method and parabolic method is used to make approximate calcalation and error estimate of the integral.

同时 ，用梯形法和抛物线法对此积分作了近似计算和误差估

Based on variation principle, a free vibration variation-integration equation of cantilever curved pipe for conveying fluid is derived. This is a bending-torsion-fluid tree phase coupled dynamics problem. It is difficult to uncouple and to obtain bending and torsion analytic solution separately. We can only look for approximate solution or numeral results.

根据变分原理导出了悬臂输液曲管的变分－积分方程，这是弯曲－扭转－流体三相藕合的动力学问题，无法解藕而单独求出弯曲和扭转的解析解，只能作近似计算。

Based on the extended Huygens-Fresnel principle and the quadratic approximation of phase structure function, we have derived the analyticl expression of the spatial degree of coherence for partially coherent flattened beams propagating through the slant turbulent atmosphere with the help of tensor integral, then analyzed the effects of different zenith angle, propagation distance, coherence of source and outer scale of turbulence on the spatial degree of coherence on the receiver.

基于广义惠更斯-菲涅耳原理和相位结构函数的平方近似，运用张量积分的方法导出了部分相干平顶光束通过斜程湍流大气传输后接收面光束空间相干度的解析表达式，分析了不同天顶角、传输距离、光源相干性以及湍流外尺度对接收面光束空间相干度的影响。

In this paper, the experience method, gas phase pseudopressure method , B-W method, oil reservoir integration method and approximation method for analysing gas condensate well testing are emphatical- ly described, and their characters, correctness and application scope are also compared.

着重介绍经验修正法、气相拟压力法、B-W方法、油藏积分法和近似法等，并比较了它们各自的特点、正确性及适用范围。

By establishing a new comparison principle,and using method of L-quasi-upper and lower solutions and mixed monotone iterative technique,the results of existence and uniqueness of solutions to Cauchy problem s of first order nonlinear integrodifferential equations in Banach spaces are obtained.

通过建立一个新的比较原理，利用L-拟上下解方法和混合单调迭代法，研究了Banach空间中一阶非线性积分微分方程初值问题解的存在唯一性，并给出了近似解的迭代序列和误差估计式。

Based on the theorems of holography and linear system,the numerical reconstructing methods of the off-axis lensless Fourier transform hologram by Fresnel diffraction formula and by the convolution method based on Rayleigh-Sommerfeld diffraction integral and by angular spectrum theorem are studied.

根据全息理论和线性系统理论，采用离轴无透镜傅里叶变换全息记录光路，对利用菲涅耳近似法、基于瑞利—索末菲衍射积分的卷积法以及角谱理论方法数值重建全息图进行了比较研究，并做了计算机模拟验证。

Objective To investigate the effects of interleukin-1 β converting enzyme gene on the biologic characteristics of ovarian cancer cells.

目的 探讨白细胞介素-1 β转换酶的表达，对卵巢癌细胞生物学特性的影响。

Campylobacter: This illness is the most commonly identified cause of diarrheal illness in the world.

弯曲：这种病是最常见的原因查明腹泻病，在世界上。