具阶段结构捕食开发模型的全局渐近行为

考虑一类具有阶段结构捕食开发模型,运用特征根分析法和迭代法得到了系统惟一正平衡点全局渐近稳定的简练条件,进一步分析了最优收获策略问题.并举例说明所得结论.     

持续共振解的拟恒等平均与多变量展开的比较

阐述了对于带缓变参数的强非线性振动系统,平均拟恒等变换与多重变量展开如何在持续共振解中首阶等价.     

有线性阻尼和变长度的单摆

应用多尺度法和势能逼近法研究有线性阻尼和变长度的单摆．通过摩擦因数与摆长慢变参数阶的比较,详细讨论了3种不同的情况并得到振幅、频率和解的渐近分析表达式．势能逼近法的应用使结果对大幅振动也有效．当摩擦因数不是很小时,修正的多尺度法用于得到更精确的首次近似解．与数值结果的比较表明本文的方法是有效的．     

Elapsed time of periodic motion with negative damping

An initially periodic motion is gradually raised out of the potential well by the effect of negative damping. The elapsed time when the motion ceases to be periodic is obtained by multiple variable expansions. An example of a strictly nonlinear system shows the result has a good approximation and is easy to calculate.     

自由电子激光器的渐近分析

对于波动器磁场纵向渐变的自由电子激光器,不仅渐变锥度对电子能量有累积影响,而且信号场的增长率对电子能量也有累积效应,这些高阶微量要以通过将运动方程和波动方程渐近展开后得到,由电子能量谐振的发生条件可以确定系统参数慢变和更慢变的２种特性以及系统信号场微速、低速和高速等３级不同的增长速率,这是一个有微摄动带慢变参数的强非线性振动系统。     

从振动系统势能井逃逸的时间

带有负阻尼的振动系统，其振幅在振动过程中逐渐增大，最终溢出势能井终止振荡现象．应用多重尺度法推得从平方非线性振动系统势能井逃逸的时间．近似势能法用于克服非线性带来的困难．数值算例证实本文的方法是有效的．     

Pendulum with linear damping and variable length

The methods of multiple scales and approximate potential are used to study pendulums with linear damping and variable length. According to the order of the coefficient of friction compared with that of the slowly varying parameter of length, three different cases are discussed in details. Asymptotic analytical expressions of amplitude, frequency and solution are obtained. The method of approximate potential makes the results effective for large oscillations. A modified multiple scales method is used to get more accurate leading order approximations when the coefficient friction is not small. Comparisons are also made with numerical results to show the efficiency of the present method.     

负阻尼周期运动的经过时间

初始时作周期运动的系统被负阻尼作用逐渐托出势能井,其周期运动的经过时间由多重变量展开解得.一强非线性系统的算例表明其结果近似性好且计算简便.