Design and Simulation of TF and TA Controller for Missile

A nonlinear terrain following(TF) and terrain avoidance(TA) controller is proposed for missile control systems. Based on classical TF algorithm (adaptive angle method), a new method for TF controller is proposed by using angle of attack. A method of obtaining terrain outline data from digital elevation map (DEM) for TF control is discussed in order to save store space. A TA algorithm is proposed by using bank-to-turn technique. The block control model, which is suitable for backstepping design, is given for nonlinear model of missile. Making full use of the characteristics of the system and combining block control principle and backstepping technique, a robust controller design method is proposed. Uncertainties in every sub-block are allowed, and can be canceled by using the idea of nonlinear damping. It is proved that the state tracking errors are converged to a neighborhood of the origin exponentially. Finally, nonlinear six-degree-of-freedom simulation results for the missile model are presented to demonstrate the effectiveness of the proposed control law.     

浅谈如何保养羊毛衫

羊毛是纺织工业的重要原料．具有许多优良特性．如弹性好、吸湿性强、保暖性好、不易沾污、光泽柔和等。在冬季里，羊毛产品受到广大消费者的青睐．虽然羊毛的纺织品价格昂贵，但人们依然对它“情有独钟”。     

陶瓷基复合材料损伤失效机理和模型研究进展

随着科学技术的进步，复合材料在航空领域得到了广泛的发展。陶瓷基复合材料因其具有高比强度、高比模量、耐高温和耐腐蚀的特性被广泛应用于航空发动机的热端部件。然而，制备过程中产生的初始损伤和残余以及复杂的失效模式，给建立陶瓷基复合材料的损伤本构模型、研究陶瓷基复合材料的损伤失效机理带来了巨大的困难。本文对陶瓷基复合材料损伤失效机理的研究进展进行综述。首先，介绍了陶瓷基复合材料的发展历史细观建模研究现状；然后，综述了陶瓷基复合材料损伤失效机理的研究现状；最后，对陶瓷基复合材料损伤失效机理研究的发展趋势进行了展望。