基于强度和刚度可靠度的结构优化设计

以结构系统的可靠性作为结构的优化控制参数。用改进的分枝限界法判认主要失效模式。用PNET法计算结构系统的可靠度。导出了强度、刚度可靠度的灵敏度分析表达式。提出最佳矢量型法的迭代公式，有效地求解了结构在系统可靠度约束下的最小重量设计问题，算例的结果说明了方法的有效性。     

基于模糊径向基神经网络的小型无人机控制系统研究

为保证小型无人机的飞行安全,提出一种由无人机飞行控制器和地面学习单元构成的两层网络学习控制系统架构。无人机飞行控制器采用模糊控制策略,学习单元采用经遗传算法优化的径向基神经网络,充分利用模糊控制和神经网络的各自优势,将模糊控制策略与RBF神经网络相结合提出了一种基于RBF神经网络的自学习模糊控制策略。所设计的飞行控制器用于无人机飞行过程中的姿态控制,仿真及实验结果表明本方法是有效的。     

月球返回舱跳跃再入弹道特性分析与优化设计

对月球返回舱跳跃再入大气层的初始再入段弹道特性与过载约束下轨迹优化问题进行了分析。首先介绍了跳跃再入的基本概念与优点,对不同再入角、不同升阻比情况下初始再入段的弹道特性进行了分析。然后采用庞特里亚金极大值原理以总吸热量最小为优化目标,对过载约束下再入轨道的初始再入段进行了优化设计,给出了升力系数的最优表达式。仿真研究表明,该方法能有效地降低飞行过程中的过载。     

一种利用纵振的直线超声电机(英文)

设计了一种利用变截面杆纵振模态工作的直线超声电机,该超声电机的特点是有两个变截面杆状并由一半圆环连接。位于圆环中间驱动足顶部质点以椭圆轨迹运动,当驱动足以一定预压力接触动子时,动子将输出直线运动。通过建立定子的有限元模型并对其进行谐响应分析验证了原理的可行性。提出了电机结构设计的要求,并通过有限元方法进行了结构参数灵敏度分析,为该类电机结构的设计提供了高效的方法。样机试验表明,该电机在100mm/s的运行速度下可以推动10N的负载。     

脉冲等离子体推力器研究综述

简要介绍了脉冲等离子体推力器(PPT)的基本工作原理;回顾了国内外脉冲等离子推力器的发展历史;阐述了它的优势与面临的挑战;分析了需要研究的关键技术与发展方向。     

FIBERSIM软件在工字梁铺层设计上的应用

针对复合材料的一种特殊形式的结构"工字梁",介绍了应用FIBERSIM软件对其进行铺层设计的方法,并对易发生错误的位置进行了详细的论述。     

An LMI-based decoupling control for electromagnetic formation flight

Electromagnetic formation flight(EMFF) leverages electromagnetic force to control the relative position of satellites. EMFF offers a promising alternative to traditional propellant-based spacecraft flight formation. This novel strategy is very attractive since it does not consume fuel. Due to the highly coupled nonlinearity of electromagnetic force, it is difficult to individually design a controller for one satellite without considering others, which poses challenges to communications.This paper is devoted to decoupling control of EMFF, including regulations, constraints and controller design. A learning-based adaptive sliding mode decoupling controller is analyzed to illustrate the problem of existing results, and input rate saturation is introduced to guarantee the validity of frequency division technique. Through transformation, the imposed input rate saturation is converted to state and input constraints. A linear matrix inequalities(LMI)-based robust optimal control method can then be used and improved to solve the transformed problem. Simulation results are presented to demonstrate the effectiveness of the proposed decoupling control.     

民机复合材料等同性验证方法及二类错误控制研究

在民用复合材料飞机的制造和适航审定过程中,复合材料等同性验证在新材料替代原材料后的适航认证方面发挥重要作用。基于复合材料等同性的验证原理,针对控制复合材料性能的关键参数,研究了等同性的验证方法。运用假设检验的方法,推导了复合材料等同性中第二类错误的理论分析方法,并提出和讨论了降低犯第二类错误概率的措施。研究表明:通常利用统计检验来比较新材料与原材料在关键性能上的差异程度以判定材料是否等同;在目前的复合材料等同性检验中,除了注意第一类错误的控制,更应该重视危害性更大的第二类错误;而增大试验样本数量能够有效降低犯第二类错误的概率;针对复合材料在民用飞机中的应用位置和受力情况来控制犯第二类错误的概率,选择等同性试验样本数量,以达到在等同性验证中既控制第二类错误又降低验证成本的目的。     

Effects of cerium salts on corrosion behaviors of Si–Zr hybrid sol–gel coatings

The present work examines the effects of cerium salts on corrosion behaviors of Si–Zr hybrid sol–gel coatings. The Si–Zr hybrid sol–gel coatings on a 2A12 aluminum substrate were prepared through hydrolysis and condensation of glycidoxypropyl-trimethoxy-silane(GTMS) and zirconium(IV) n-propoxide(TPOZ). Used as inhibitors for corrosion, three types of cerium salts(Ce(NO_3)_3, CeCl_3, and Ce(CH_3COO)_3) were doped into the sol–gel coatings. Fourier transform infrared(FTIR) and scanning electron microscopy(SEM) were employed to investigate the structures and morphologies of various coatings, and the corrosion resistances of the coatings were evaluated by electrochemical methods and neutral salt spray tests. Experimental results indicate that the addition of cerium salts can hinder the process of corrosion due to their self-healing abilities. Furthermore, the sol–gel coating doped with Ce(CH_3COO)_3 has the best corrosion resistance because of the promotions of hydrolysis and condensation provided by CH_3COO.     

Evaluation of simulation-based training for aircraft carrier marshalling with learning cubic and Kirkpatrick’s models

Simulation-based training is a promising way to train a carrier flight deck crew because of the complex and dangerous working environment. Quantitative evaluation of simulation-based training quality is vital to make simulation-based training practical for aircraft carrier marshalling.This paper develops a personal computer-based aircraft carrier marshalling simulation system and a cave automatic virtual environment(CAVE)-based immersive environment. In order to compare the training effectiveness of simulation-based training and paper-based training, a learning cubic model is proposed and a contrast experiment is carried out as well. The experimental data is analyzed based on a simplified Kirkpatrick’s model. The results show that simulation-based training is better than paper-based training by 26.80% after three rounds of testing, which prove the effectiveness of simulation-based aircraft carrier marshalling training.