微分

Based on the study of characteristic equation,we obtain some new oscillationcriteria for higher order neutral differential equations.

本文利用特征方程，建立了高阶中立型泛函微分方程新的振动准则，推广了文[1][2]中的工作，改进了文[3]中的结果

In the range of 200~600 nm,the absorbance at 12 wavelengths was taken as characteristic parameter of artificial neural network.

人工神经网络是在生物学中神经网络理论的基础上，简化了复杂结构的偏微分方程，构成了多个神经元互联网络的结构，研究这

In this paper, we study the differential form Wus method and put emphasis on the algorithm of differential characteristic set for differential polynomial system, and its applications.

首先，在系统总结微分情形吴方法的算法的基础上，提出了一种简化算法′算法，并给出了相应的理论证明。

Differential characteristic set method ofdifferential polynomial system is used to overcome the huge difficulties in calculation.

在本文的计算过程中，用Mathematica软件编写的求解微分特征列集的程序包克服了现有计算方法中的一些困难，在很大程度上减少了本文的计算量。

Routh-Hurwitz is used to determine that the characteristic equation has negative real root, and Center-Manifold theorem is used to study the stability of autonomous differential system in the case of hyperbolic and non-hyperbolic at the equilibrium point.

利用Routh-Hurwitz判定特征方程有负实部根，并利用中心流形定理研究了自治微分系统在平衡点处双曲和非双曲情况下的稳定性，由此产生系统趋于不同稳定点时病毒分裂的临界值，同时利用数值模拟验证了分析的合理性。

The use of charged particle in an electromagnetic field equations of motion and solve the differential equations.

把电磁作用力作用到一个粒子上得出了Lorentz力公式，利用带电粒子在电磁场中的运动方程并解这个微分方程。

Spectral element methods for partial differencial equation is introduced in this study from viewpoint of the collocation approximation of Chebyshev polynomial. Wave Equation and its space discretization are deduced. Two time integral methods, central difference method and implicit Newmark method, are introduced, and their stability and applicability are also discussed in some details. The significance of absorbing boundary conditions in spectral element methods for Aeroacoustics is explained, and Clayton-Engquist-Majda absorbing boundary conditions is emphasized and introduced, then the discrete scheme of this boundary conditions is deduced and applied to spectral element methods for wave equation.

本文从Chebyshev多项式逼近理论出发，详细介绍了谱元方法求解偏微分方程的过程；推导了流体中的声波动方程并在空间上对其进行了谱元离散；详细讨论了两种时间积分方法──中心差分法和Newmark方法，分析了它们的稳定性条件，并从理论上对比了两种方法的优缺点和适用范围；将吸收边界条件推广应用于谱元方法求解气动声学问题中，重点介绍了Clayton-Engquist-Majda吸收边界条件的原理和公式，推导了该吸收边界条件的变分形式，并将其引入波动方程的离散形式中。

Because any reports on the active control of rotating disk haven't be seen in China up to now, and this experiment research is important, so the complete set of active control system of rotating disk are built independently. The push-pull type electromagnet is applied to control the vibration of the circular disk. The power amplifier circuit that can respond to wide scope in frequency from DC to AC is designed by improving the existing circuit. The sensor signal is first low-pass filtered, then the proportional control plus the differential control circuit easy used in practice are applied to finish the more effective control. The electromagnetism shield is used as possible to decrease the signal disturbance from the electromagnet to eddy sensor.

考虑到目前国内尚未见到有关旋转圆盘振动主动控制的相关报导以及实验的重要性，自行设计制作了一整套旋转圆盘振动主动控制系统：提出并采用推拉型电磁作动器来控制圆盘的振动；在改进现有电路的基础上，自行设计了具有较理想特性的驱动电磁作动器的功率放大器；根据实际控制环境的特点，设计了先进行低通滤波，再采用比例和实用的近似微分电路构成的控制器，并采用了电磁屏蔽来减小电磁铁对传感器的干扰，以实现更有效的控制。

Second, proceeding with the fact thatthe constructing vector wave functions of conventional circular cylindrical and sphericalvector wave functions are linear independent solutions to the electromagnetic field waveequations in biisotropic medium,spectral impedance boundary conditions are proposed forinfinitely long perfectly conducting circular cylinder and sphere coated with biisotropic media,respectively,which generalize the applicable range of planar structures and are suitable toanalyze the electromagnetic problems involving their counterpart structures.

所用的方法是在Fourier变换谱域中的一阶线性微分方程组理论和矩阵技术，提出了适用于Chiral媒质半空间辐射问题的耦合镜像原理(即镜像电流的振幅和相位是由Chiral媒质中的本征左、右旋圆极化波相互耦合来确定的)和适用于研究平面分层Chiral媒质电磁问题的一般性更高的分析方法。

Circular accelerator ; equilibrium orbit ; two-point boundary value problem ; non-linear differential equation

圆形加速器；平衡轨道；二点边值问题；非线性微分方程

According to the clear water experiment, aeration performance of the new equipment is good with high total oxygen transfer coefficient and oxygen utilization ratio.

曝气设备的动力效率在叶轮转速为120rpm～150rpm时取得最大值，此时氧利用率和充氧能力也具有较高值。

The environmental stability of that world - including its crushing pressures and icy darkness - means that some of its most famous inhabitants have survived for eons as evolutionary throwbacks, their bodies undergoing little change.

稳定的海底环境─包括能把人压扁的压力和冰冷的黑暗─意谓海底某些最知名的栖居生物已以演化返祖的样态活了万世，形体几无变化。