Stiffeners layout design of thin-walled structures with constraints on multi-fastener joint loads

The purpose of this paper is to present an extended topology optimization method for the stiffeners layout design of aircraft assembled structures.Multi-fastener joint loads and manufacturing constraints are considered simultaneously.On one hand,the joint loads are calculated and constrained within a limited value to avoid the failure of fasteners.On the other hand,the manufacturing constraints of the material distribution in the machining directions of stiffeners are implemented by an improved piecewise interpolation based on a beveled cut-surface.It is proven that the objective function is strictly continuous and differentiable with respect to the piecewise interpolation.The effects of the extended method with two different constraints are highlighted by typical numerical examples.Compared with the standard topology optimization,the final designs have clearly shown the layout of stiffeners and the joint loads have been perfectly constrained to a satisfying level.     

考虑运动学约束的不规则目标遗传避碰规划算法

 针对复杂环境下不规则目标的路径规划问题,提出了一种带有运动学约束的遗传避碰规划算法。以舰载机在航母甲板上的路径规划问题作为研究对象,并且该算法可推广至其他具有此类约束的路径规划问题中,它较好地解决了目标形状复杂、障碍环境复杂、目标运动时带有回转半径约束等特殊问题。在传统遗传路径规划算法的基础上,针对性地设计了三维位置和姿态混合编码、三段法路径解码、轨迹包围盒的碰撞检测及距离计算等方法,并在遗传操作中引入惩罚项和修补策略来辅助算法寻优。最后,为得出复杂环境下的最优路径,基于VC++平台对算法进行了仿真验证。结果表明,在复杂障碍环境下,本文提出的算法可求得最优避碰路径,并满足预先设定的目标回转半径约束,能够有效地解决此类目标的避碰路径规划问题。     

基于航路耦合容量的协同多航路资源分配

针对中国当前航路空域拥挤日益严重的问题,分3个步骤进行解决:第1步,对空域管制单元之间存在的交通流耦合因素进行分析,建立基于空域管制单元耦合因素的航路容量模型;第2步,为反映不同类型航班对计划到达时间变动范围的不同接受程度,定义了航班的延误成本函数和改航成本函数;第3步,在上述两步的基础上,为充分利用可行的航路空域资源...     

基于弹性网稀疏编码的空间目标识别

 传统的特征袋(BoF)模型在目标识别过程中假设每个局部特征点只关联特征词典中一个视觉单词。此外,l₁范数约束下的稀疏编码对于具有较强成对相关性的特征通常只选择一个特征,而不关注哪一个特征被选择。本文提出一种基于弹性网稀疏编码的特征袋模型。该模型利用尺度不变特征变换(SIFT)特征描述子构建特征字典,再通过弹性网回归模型求解每个描述子所对应的稀疏系数向量,最后将目标图像内的稀疏系数向量合并用于分类。与传统的特征袋模型和基于l₁范数稀疏编码的特征袋模型相比,该模型有较好的识别性能,并对视角变化具有较强的鲁棒性。在空间目标图像数据库上的实验验证了该模型的有效性。     

Impact time control guidance against maneuvering targets based on a nonlinear virtual relative model

Aiming at the problem of high-precision interception of air-maneuvering targets with impact time constraints, this paper proposes a novel guidance law based on a nonlinear virtual relative model in which the origin is attached to the target. In this way, the original maneuvering target is transformed into a stationary one. A polynomial function of the guidance command in the range domain with two unknown coefficients is introduced into the virtual model, one of the coefficients is determined to ...     

带攻击角度约束的有限时间收敛制导律

针对航空制导武器带有攻击角度约束打击地面目标的制导问题,提出了基于快速非奇异终端滑模的有限时间收敛制导律.通过引入非奇异终端滑模面,避免了制导过程中可能产生的奇异问题,该制导律具有快速收敛的特性,能够满足攻击角度约束的要求.基于Lyapnov稳定理论证明了有限时间收敛的特性,并给出了收敛时间表达式.仿真结果表明,该制导律具有快速收敛特性,能够满足脱靶量和末端攻击角度的要求,相比传统带落角约束制导律,具有一定的优越性.     

带落角约束的虚拟目标实时轨迹生成算法

针对导弹带落角约束条件打击目标的要求,在纵向平面内,根据导弹和目标的实时运动轨迹,提出了一种虚拟目标实时轨迹生成算法,并且给出了该算法中所需要的目标实时位置信息的估算方法.仿真结果表明,以该算法得出的虚拟目标轨迹作为导弹的跟踪对象,采用变结构导引律能满足落角约束条件,并且能够提供很高的命中精度,从而证明了该算法的正确性和有效性,为带落角约束条件打击目标提供了一种新的思路和途径.     

YIDOYU及其在飞机设计中的应用

 本文介绍了飞机结构多约束优化设计系统(YIDOYU)的主要功能、特点和程序组织概貌,并着重介绍了系统的应用情况。实例应用结果表明YIDOYU是一个实用的优化设计系统,显示了其解决不同结构优化设计问题的能力和效率。     

三维弹塑性缺口问题的应变等效法

通过对三维应力约束下含中心圆孔的双向拉伸板进行弹塑性理论分析,提出线弹性等效应变解与弹塑性等效应变解之间存在的内在关系,弹塑性等效应变解可以由线弹性解通过简单的变理代换得到。利用二维和三维弹塑性有限元分析证实,在一般制品几何情况下,本文提出的应变等效法比著名的Neuber法和等效应变能密度法具有更高的精度和适应能力,并且可经给出弹塑性全场解,对不同缺口形状,不同材料,不同载荷情况具有通用性,可以作为有限元法的补充,为结构的细节设计和寿命分析提供了高效的工程方法。     

刚体航天器姿态跟踪的时变滑模控制(英文)

To solve the problem of attitude tracking of a rigid spacecraft with an either known or measurable desired attitude trajectory, three types of time-varying sliding mode controls are introduced under consideration of control input constraints. The sliding surfaces of the three types initially pass arbitrary initial values of the system, and then shift or rotate to reach predetermined ones. This way, the system trajectories are always on the sliding surfaces, and the system work is guaranteed to have robustness against parameter uncertainty and external disturbances all the time. The controller parameters are optimized by means of genetic algorithm to minimize the index consisting of the weighted index of squared error （ISE） of the system and the weighted penalty term of violation of control input constraint. The stability is verified with Lyapunov method. Compared with the conventional sliding mode control, simulation results show the proposed algorithm having better robustness against inertia matrix uncertainty and external disturbance torques.