基于改进Q学习的IMA系统重构蓝图生成方法

重构蓝图定义了故障状态下系统软硬件资源的重新配置方案，是实现综合模块化航空电子系统重构容错的关键。提出了一种基于改进Q学习的重构蓝图生成方法，综合考虑负载均衡、重构影响、重构时间、重构降级等多优化目标，并应用模拟退火框架改进探索策略，提高了传统Q学习算法的收敛性能。实验结果表明，与模拟退火算法、差分进化算法、传统Q学习算法相比，本文提出的改进Q学习算法效率更高，所生成重构蓝图质量更高。     

燃油离心泵多目标优化设计及仿真分析

针对燃油离心泵高效、高抗汽蚀优化设计问题,进行了基于损失模型和SQP算法下的多目标优化设计并进行了仿真应用。首先,考虑叶轮、蜗壳等通流部件内的水利损失、容积损失以及机械损失,建立表征离心泵效率的综合损失模型；结合基于必须汽蚀余量计算下的汽蚀表征函数以确定离心泵多目标函数。进而,利用SQP算法构造合理的适应度函数,结合约束条件确定离心泵多目标优化设计的数学模型。其次,对某型燃油离心泵进行基于SQP算法的优化设计并与其他常用优化算法进行对比。可以看到：各优化算法的最优结果几乎相似,但SQP算法对多维非线性方程组优化求解所用的迭代步数相对较少。最后,利用CFD技术进行仿真及外特性预测,以验证基于SQP算法下燃油离心泵多目标优化设计的有效性。结果表明：相比传统方法设计的原型离心泵,基于SQP算法优化的离心泵内流场压力分布相对均匀,流动损失更低,且进口流动有利于抗汽蚀性能；从外特性结果来看,基于SQP算法优化的离心泵高效工作区域相对宽广,必须汽蚀余量相对较低,抗汽蚀性能有所改善。     

Hypersonic reentry trajectory planning by using hybrid fractional-order particle swarm optimization and gravitational search algorithm

This paper proposes a novel hybrid algorithm called Fractional-order Particle Swarm optimization Gravitational Search Algorithm (FPSOGSA) and applies it to the trajectory planning of the hypersonic lifting reentry flight vehicles. The proposed method is used to calculate the control profiles to achieve the two objectives, namely a smoother trajectory and enforcement of the path constraints with terminal accuracy. The smoothness of the trajectory is achieved by scheduling the bank angle with the aid of a modified scheme known as a Quasi-Equilibrium Glide (QEG) scheme. The aerodynamic load factor and the dynamic pressure path constraints are enforced by further planning of the bank angle with the help of a constraint enforcement scheme. The maximum heating rate path constraint is enforced through the angle of attack parameterization. The Common Aero Vehicle (CAV) flight vehicle is used for the simulation purpose to test and compare the proposed method with that of the standard Particle Swarm Optimization (PSO) method and the standard Gravitational Search Algorithm (GSA). The simulation results confirm the efficiency of the proposed FPSOGSA method over the standard PSO and the GSA methods by showing its better convergence and computation efficiency.     

速度脉动下分层旋流火焰动态传播结构提取

为了深刻理解分层旋流火焰的动态结构，开展了分层旋流火焰动态的模态分析和参数化研究。实验在BASIS （北京航空航天大学发展的具有台阶隔离段的独立分层旋流燃烧器）上开展，以甲烷为燃料预混燃烧，使用高速摄像捕捉了速度脉动下的CH*化学发光信号动态图像。利用传统的本征正交分解（POD）和重定向POD分析了火焰动态特性，并利用重定向POD提取了火焰动态中沿着轴向和径向的周期性传播结构，传播结构的频率与速度脉动频率保持一致，且轴向模态的传播结构最为明显。同时，研究了总当量比对重定向POD模态的影响，分析表明：总当量比增大时，重定向POD模态的拓扑结构会发生变化；重定向POD模态中出现了错位现象，这种现象与相平均图像中的火焰传播行为保持一致。重定向POD方法能够有效提取旋流火焰动态中的传播结构，为旋流火焰燃烧不稳定性的机理研究提供了一种分析工具。     

An error analysis and optimization method for combined measurement with binocular vision

The accurate measurement of surfaces of large aviation components is vital for the assessment of manufacturing and assembly quality of such components. To satisfy the measurement requirement of large-size components, most current researches pay more attention to combined measurement methods utilizing different measuring instruments, but the related researches on error analysis and optimization methods are not taken enough attention. This paper proposes a combined laser-assisted measurement method with feature enhancement techniques, and it also develops an error propagation model of the main factors affecting the overall measurement error in detail. Firstly, the surface of a large-size component is measured by the measurement system at multiple stations. Secondly, a control point coordinate system is established as a bridge to unify all local measurement data into the global coordinate system. To improve the overall measurement accuracy, the pixel extraction error as a key factor causing the overall measurement error is analyzed in detail. Next, the error propagation model is established, and some optimization strategies of layout for minimizing measurement error and transformation error are researched. Finally, experiments are carried out to verify the effectiveness of the proposed method. The results show that the measurement error of the proposed method reaches 0.073% and 0.14% with a 1D standard ruler and a flat plate, respectively.     

面向集中力扩散的回转曲面加筋拓扑优化方法

为了提高航天器回转曲面加筋型连接结构的集中力扩散效率，需要开展回转曲面加筋集中力扩散结构设计。传统放射肋设计方法普遍依赖设计经验、难以满足集中力高效扩散需求。因此，提出一种面向集中力扩散的回转曲面加筋拓扑优化方法。第1步，建立了一种基于各向异性过滤技术的集中力扩散拓扑优化方法，保证拓扑优化结果满足回转曲面加筋制造工艺要求；第2步，提出了一种基于网格变形技术的拓扑优化结果智能重构方法，可高效准确地对回转曲面加筋拓扑优化结果进行模型自动重构。基于所提出方法，以卫星平台对接环这种典型的回转曲面加筋壳为对象开展算例研究，并将优化结果与传统放射肋设计结果进行对比。结果表明，所提出的优化方法可得到加筋构型清晰、满足回转曲面加筋制造工艺要求的优化结果，且具有集中力扩散效率高、网格质量依赖性低、拓扑特征重构高效等优点。     

Design of nanofluid-cooled heat sink using topology optimization

The paper presented topology optimization of 2D and 3D Nanofluid-Cooled Heat Sink (NCHS). The flow and heat transfer problem in the NCHS was treated as a single-phase nanofluid based convective heat transfer model. The temperature-dependent fluid properties were taken into account in the model due to the strong temperature-dependent features of nanofluids. An average temperature minimum problem was studied subject to the fluid area and energy dissipation constraints by using the density method. In the method, the design variable is updated according to the gradient information obtained by an adjoint based sensitivity analysis process. The effects of the energy dissipation constraint, temperature-dependent fluid properties and nanofluid characteristics on optimal configurations of NCHS were numerically investigated with following conclusions. Firstly, branched flow channels in the optimal configuration increased with the rise of the allowed energy dissipation. Secondly, temperature-dependent fluid properties were significant for obtaining the appropriate optimal results with best cooling performance. Thirdly, heat transfer performances of optimal configurations were enhanced by reducing the nanoparticle diameter or increasing the nanoparticle volume fraction. Fourthly, the optimal configuration for nanofluid had better cooling performance than that for its base fluid.     

Weibull分布参数估计值对细节疲劳额定强度的影响

将新材料、新工艺应用于民机结构设计时，细节疲劳额定强度（DFR）法仍是重要的评估方法。根据新型铝合金疲劳试验数据，全面分析了Weibull分布形状参数对DFR计算参数的影响；分析标准S-N曲线斜度参数对DFR的影响时，应考虑可靠性寿命的变化，采用低可靠度寿命计算曲线斜度参数可降低Weibull分布形状参数的影响；比较了采用不同分布参数估计值与传统上采用波音公司给定值进行DFR计算的差异。结果表明，对于通过符合性检验的试验数据，使用不同Weibull分布的参数估计值计算得到的DFR都大于按传统方法（用波音公司给定值）的计算结果，其中，三参数Weibull分布计算的DFR最大，至少增加10%以上。     

Multi-scale design and optimization for solid-lattice hybrid structures and their application to aerospace vehicle components

By integrating topology optimization and lattice-based optimization, a novel multi-scale design method is proposed to create solid-lattice hybrid structures and thus to improve the mechanical performance as well as reduce the structural weight. To achieve this purpose, a two-step procedure is developed to design and optimize the innovative structures. Initially, the classical topology optimization is utilized to find the optimal material layout and primary load carrying paths. Afterwards, the solid-lattice hybrid structures are reconstructed using the finite element mesh based modeling method. And lattice-based optimization is performed to obtain the optimal cross-section area of the lattice structures. Finally, two typical aerospace structures are optimized to demonstrate the effectiveness of the proposed optimization framework. The numerical results are quite encouraging since the solid-lattice hybrid structures obtained by the presented approach show remarkably improved performance when compared with traditional designs.     

Effects of wing flexibility on aerodynamic performance of an aircraft model

The low-speed wind tunnel experiment is carried out on a simplified aircraft model to explore the influence of wing flexibility on the aircraft aerodynamic performance. The investigation involves the measurements of force, membrane deformation and velocity field at Reynolds number of 5.4 × 10⁴–1.1 × 10⁵. In the lift curves, two peaks are observed. The first peak, corresponding to the stall, is sensitive to the wing flexibility much more than the second peak, which nearly keeps constant. For the optimal case, in comparison with the rigid wing model, the delayed stall of nearly 5° is achieved, and the relative lift increment is about 90%. It is revealed that the lift enhanced region corresponds to the larger deformation and stronger vibration, which leads to stronger flow mixing near the flexible wing surface. Thereby, the leading-edge separation is suppressed, and the aerodynamic performance is improved significantly. Furthermore, the effects of sweep angle and Reynolds number on the aerodynamic characteristics of flexible wing are also presented.