根据一阶拟线性偏微分方程组的特征理论，讨论内弹道两相流方程组的类型。

Following the theory on characteristics of first order quasi-linear partial differential equations, classification of the balance equations for two-phase flow in interior ballistics is discussed.

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利用随机微分方程理论，对一类具有随机特征的风险投资组合问题进行深入研究。

With the theory of stochastic differential equation, the authors discuss a problem of a class of risk investment portfolio with stochastic character.

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本文利用特征方程根的性质，研究了开口圆柱薄壳精确微分方程的特征方程的渐近解。

Using the root of the characteristic equation, this paper studies the asymptotic solution of the characteristic equation of the open circular cylindrical thin shells.

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