数值函数

And global stability of boundary equilibrium, which implies the extinction of the predator population, is studied by the limit system theory and Dulac criterion.

所得结论适用于具有Holling type-Ⅱ、Ⅲ和Rosenzweig功能反应函数的捕食模型，最后通过数值模拟来验证所得结论。

The 2-D transfer function of the bistatic SAR is obtained. Azimuth position distortion along range existing in the original alogrithm is corrected by mapping from scene coordinate to azimuth-slant distance coordinate. Bistatic SAR date can still be processed by a mono-static SAR processor. The efficaciousness of the proposed algorithm is verified through point target simulations.

算法通过数值计算得到双基地二维传递函数，通过场景坐标系向方位－斜距平面的映射校正了原算法中存在的沿距离变化的方位位置畸变，进而来用常规单基地SAR成像处理流程实现对双基地SAR回波数据的成像处理，最后通过点目标仿真验证了算法的有效性。

Electric machinery and electrotechnology ; Multi-layer earth structure ; Green Function ; Numerical calculation

电机电工；多层土壤；格林函数；数值计算

Within this algorithm, Alopex algorithm is used to Elitist maintained Genetic Algorithm.

数值计算结果表明该算法优于求解函数优化的EGA和Alopex算法。

In this paper, propose a new method based on the MATLAB/PDETOOL Box to solve the definite solution problems for elliptic equation problem, and the needed time of the program for the different nodes.

基于有限元的MATLAB/PDETOOL工具箱库函数，对MREIT中的椭圆方程定解问题进行数值求解，还给出了求解规则区域的定解问题时，不同节点所需的运算时间。

The expm1 function returns the value of Ex-1, where E is Euler's constant (approximately 2.7183) and x is the number passed to it.

expm1函数的作用是：计算 e（自然对数的底，其数值大约等于2.7183）的指数；它返回了exp 1的值，甚至当number的值接近零也能计算出准确结果。

Combining NA samples the EB estimation with convergence rates is also obtained; Thirdly, for one-parameter exponential distribution family, we give the parameters' EB estimator that is admissible and asymptotically optimal with convergence rates. Finally, Bayesian and hierarchical Bayesian approaches are applied to analyze the reliability performances for series system with cold standby units and the numerical simulation results show that multiple Bayes estimator is superior to Bayes estimator.

其次，针对一类双边截断分布族，在非对称linex损失下构造了经验Bayes决策函数，建立了它的收敛速度，给出了渐近最优的证明；并结合NA样本研究了参数的经验Bayes估计及其收敛速度；接着给出了指数族参数的经验Bayes估计，证明了它是渐近最优的，也是可容许的，同时也获得了该EB估计的收敛速度；最后，运用Bayes与多层Bayes方法研究了具有冷贮备部件串联系统的可靠性指标的估计，并给出了数值模拟结果，结果表明多层Bayes估计优于Bayes估计。

The solution to the dual integral equations with exponential function can be discussed,too.

最后给出了含余弦函数对偶积分方程的数值算例。

In this article two functional modes of the Fly-back Converter (Continuous Conduct Mode and Discontinuous Conduct Mode) are particularly analyzed, which include their characteristics, applications, the critical pattern of two functional modes is argued, both the exact boundary from the angle of circuit parameters is crystallized, at the same time, basic principle of PFC under the DCM mode is introduced, which settle theoretical basis for the subsequent design; by establishing the mathematic model of the converter, a further investigation of the configuration is made, qualitatively and quantitatively, analyzed to settle exactly theoretical basis for the subsequent emulation and the experimental parameter; from the angle of steady-state analysis, the transfer function of the system is deduced to establish dynamic small-signal state equation, emulating the system with the help of matlab, then according to the simulation result and the theory of PFC revise the system, lastly, we adopt the project which add a zero-pole compensator to the voltage loop, by this way, a satisfied system performance is gained and the PFC scheme is ensured successfully; finally, based on the previously-done work, we combining with the situation of specific design requirement, acquired the numerical value of each unit devices in this converter

详细分析了反激式变换器的两种工作状态，连续模式(Continuous Conduct Mode ，简称CCM)和断续模式(Discontinuous Conduct Mode，简称DCM)以及各自的特点、应用场合，论证了两种工作状态的临界模式，从电路参数的角度明确了二者的界限，同时还介绍了DCM模式下PFC的基本原理，为后面的设计奠定理论基础；通过对整个变换器系统建立准确的数学模型，对此变换器的电路结构做了进一步的研究，定性、定量地分析了变换器各部分的工作状态，为仿真和实验参数的确定以及电路参数的优化提供理论依据；从稳态分析的角度，为系统建立了动态小信号状态方程并推导出系统的传递函数，利用matlab对系统进行仿真，进而根据仿真结果以及PFC的相关理论对系统进行校正，采用在电压环加入零点—极点补偿器的设计方案，得到了满意的系统特性并且保证了PFC的顺利实现；最后，在前面所做工作的基础上，结合设计要求计算出此变换器系统中每个元器件的数值，利用Pspice对其进行了仿真、优化，然后根据仿真结果搭建了硬件电路。

Using Landauer-Buttiker formulism the analytical expressions for the electronic transmission probability as a function of incident electron energy and geometry parameters are obtained, with which the conditions for interference maximum and minimum of electron wave are indicated analytically and verified numerically.

用Landauer-Büttiker公式解析地计算出了两种情况下系统电子透射率作为入射电子能量和系统几何参数的函数表达式，从而分析得出了由于量子干涉产生透射极大与极小值时入射能量与几何参数所满足的条件关系并得到了数值验证。

We have no common name for a mime of Sophron or Xenarchus and a Socratic Conversation; and we should still be without one even if the imitation in the two instances were in trimeters or elegiacs or some other kind of verse--though it is the way with people to tack on 'poet' to the name of a metre, and talk of elegiac-poets and epic-poets, thinking that they call them poets not by reason of the imitative nature of their work, but indiscriminately by reason of the metre they write in.

索夫农 、森那库斯和苏格拉底式的对话采用的模仿没有一个公共的名称；三音步诗、挽歌体或其他类型的诗的模仿也没有——人们把&诗人&这一名词和格律名称结合到一起，称之为挽歌体诗人或者史诗诗人，他们被称为诗人，似乎只是因为遵守格律写作，而非他们作品的模仿本质。

The relationship between communicative competence and grammar teaching should be that of the ends and the means.

交际能力和语法的关系应该是目标与途径的关系。