二重积分

This method was based on rotation formula of the current magnetic field and the magnetic fields can be expressed by a double integration about spatial radial coordinate and spatial wave number of Bessel function.

由电流磁场的旋度公式出发，推导了多层介质中点电流源磁场的表达式，其为一个关于空间径向坐标和贝塞尔函数空间波数的二重积分。

If is continuous on the closed region , then there exists at least a point in such that , where is the area of .

性质 7(二重积分的中值定理)若在闭区域上连续，则在上至少存在一点使得，其中是区域的面积

And I is the double integral of over D ,written ,or

这样就称f在D上可积，I称为f在D上的二重积分，记作或

A new ergodic capacity formula is derived which can be expressed as a double integral.

为此推导了一个新的遍历容量公式，该公式可表示为一个二重积分。

Some well-known results on area transformation formula and variant transformation formula of double integral are improved and generalized.

对现有的有关面积变换公式和二重积分变量变换公式的结果作了相应的改进和推广。

From the theory and examples, the article points out why in the symmetric block the calculation of the double integral is easy to go wrong and offers some methods to avoid errors.

从理论和实例两个方面，指出了对称区域上二重积分计算中易出现问题的原因，并给出了避免错误的方法。

This paper introduces the concept of double integral, the fundamental nature and its application.

马超(三亚航空旅游职业学院，机电系，海南，三亚，572000)摘要：本文介绍了二重积分的概念、基本性质及其应用。

The integral calculus of Bernhard Riema of the function .

2齐次 函数的二重积分。

The probability limit theorem is used to design a kind of Monte Carlo method of dual integral.

利用概率极限定理思想，设计二重积分的蒙特卡罗算法，通过方差分析，选择适当的随机数，得到了理论意义下的方差最小算法，用实际算例验证了该方法的优良性。

During the simulation, surface current from primary electrode is computed. Taking rectangular triangle as the mesh unit, the integral formula of surface current can be simplified to a product of a difference expression and the surface area. So the computation complexity of FEM will be decreased and the time-cost will be cut down greatly.

在模拟过程中，需要计算主电极表面电流，通过选用直角三角形作为离散单元，将表面电流的二重积分表达式简化为一个差商表达式与主电极表面积的乘积，极大地降低了有限元分析的复杂度，减少了计算时间。

The basic concept of FOP can be summarized as to further optimize effective prescription according to the standard of curative effects and with the aid of modern science and technology and theories of traditional Chinese medicine.

其基本内涵可概括为：以确有疗效的中药复方为研究对象，以现代科学技术和传统中医药理论为技术支持，以该复方所治病证的药效响应为评价标准，以优化重组疗效更优的新复方为研究目的。

Ever since our world has been a world, native forests have been indiscriminately exploited by man.

自从我们的世界一直是世界原生森林被任意剥削人。