Optimization of multi-revolution low-thrust transfer based on modified direct method

A modified direct optimization method is proposed to solve the optimal multi-revolution transfer with low-thrust between Earth-orbits. First, through parameterizing the control steering angles by costate variables, the search space of free parameters has been decreased. Then, in order to obtain the global optimal solution effectively and robustly, the simulated annealing and penalty function strategies were used to handle the constraints, and a GA/SQP hybrid optimization algorithm was utilized to solve the parameter optimization problem, in which, a feasible suboptimal solution obtained by GA was submitted as an initial parameter set to SQP for refinement. Comparing to the classical direct method, this novel method has fewer free parameters, needs not initial guesses, and has higher computation precision. An optimal-fuel transfer problem from LEO to GEO was taken as an example to validate the proposed approach. The results of simulation indicate that our approach is available to solve the problem of optimal muhi-revolution transfer between Earth-orbits.     

试论大学文化的基本特征

大学文化是中国特色社会主义文化的重要组成部分,它是高校生存和发展的根基与灵魂,也是一所高校实现可持续发展的重要保证。研究其内涵和特征对于高校的发展来讲是十分重要的。     

基于改进配点法的星际小推力轨道设计与优化

星际小推力转移轨道的设计与优化是深空探测研究中的关键技术之一.传统的标准配点法是求解问题非常有效的方法,但计算精度较低.针对双积分轨道动力学模型给出了改进配点算法,在不增加非线性规划问题约束的条件下,采用四阶Gauss-Labatto积分式处理系统微分方程,提高了配点法的计算精度.然后以地球-金星的燃料最省小推力转移轨道为例,分别采用标准配点法和改进配点法对其进行了优化设计,并分析比较了优化结果.数值计算结果验证了改进配点法的有效性.     

压力蒸汽灭菌法在中药制剂生产中的应用

概述了中药材灭菌中存在的问题,通过对各种中药材用压力蒸汽灭菌法、乙醇压力蒸汽灭菌法进行试验,提出了适合中药材灭菌的方法,并探讨了压力蒸汽灭菌法在中药制剂生产中的应用。     

基于最优状态反馈的小推力转移轨道制导策略

针对小推力变轨技术研究中的难点之一——飞行器的制导问题,提出了一种基于最优状态反馈的自主制导策略。首先利用传统Gauss型运动方程,推导出三个轨道根数增大最快的独立控制律;然后根据当前根数与目标值的偏差量对独立控制律进行加权组合;最后为高效可靠地获得最优制导律,采用一种遗传算法和逐次二次规划相结合的混合方法对权重进行了优化。该制导算法设计简单,无须预存参考轨道,能够实现飞行器的自主制导,并且具有燃料消耗次优的特点。仿真计算验证了该算法的有效性。