基于权衡空间探索的多约束弹道初值确定方法

运载火箭弹道设计对初值的选取敏感,需要设计人员具备相应经验,新构型或新任务下迭代设计易发散,设计过程依靠人员手动调整,效率较低。应用权衡空间探索及全局优化思想,给出了多约束弹道设计初值确定方法,并在此基础上重新建立了弹道设计流程,自动完成初值选取及精确设计,降低了设计过程对人员经验的依赖性,提升了弹道设计方法的智能化程度,提高了论证及设计效率。     

Banach空间中的常微分方程边值问题的拟上下解方法

利用拟上下解方法,研究了一阶非线性微分方程边值问题u′(t)=f(t,u(t)),u(0)-u(T)=x1,x1≥0拟解的存在性,并通过线性微分方程的解来构造算子,从而得到单调迭代序列,进而得到该边值问题的最大最小拟解对。     

表面温度和热流的一种间接测量技术

固体表面温度和热流的直接测量在某些情况下是很困难的。使用“过去的”和“将来的”测量时间 ,引入稳定矩阵的概念 ,抑制了导热反问题的误差放大作用。通过埋设在固体内部的热电偶的温度测量 ,同时对固体表面的温度和热流进行了有效估算     

用于表面温度测量的导热反问题的误差研究

讨论了用于温度测量的非稳态一维线性导热反问题。通过引入正则参数 ,这种不适定问题得到了稳定的解。在给出非级数形式的分析解后 ,计算误差可以通过数值解与准确解的比较确定。同时讨论了影响计算误差的各种因素。     

Aerial-ground collaborative routing with time constraints

The advancement of autonomous technology makes electric-powered drones an excellent choice for flexible logistics services at the last mile delivery stage. To reach a balance between green transportation and competitive edge, the collaborative routing of drones in the air and trucks on the ground is increasingly invested in the next generation of delivery, where it is particularly reasonable to consider customer time windows and time-dependent travel times as two typical time-related factors in daily services. In this paper, we propose the Vehicle Routing Problem with Drones under Time constraints (VRPD-T) and focus on the time constraints involved in realistic scenarios during the delivery. A mixed-integer linear programming model has been developed to minimize the total delivery completion time. Furthermore, to overcome the limitations of standard solvers in handling large-scale complex issues, a space-time hybrid heuristic-based algorithm has been developed to effectively identify a high-quality solution. The numerical results produced from randomly generated instances demonstrate the effectiveness of the proposed algorithm.     

Geometric problem solving with strings and pins

Humans solve spatial and abstract problems more easily if these can be visualized and/or physically manipulated. We analyze the domain of geometric problem solving from a cognitive perspective and identify several levels of domain abstraction that interact in the problem solving process. We discuss the roles of physical manifestations of spatial configurations, their manipulation, and their perception for understanding problem solving processes. We propose an extension of the classical problem solving repertoire of constructive geometry to approach certain problems more directly than under the compass-and-straightedge paradigm. Specifically, we introduce strings and pins as helpful metaphors for a generalization of the constructive geometry approach. We present classical problems from spatial problem solving to illustrate the ‘strings and pins’ paradigm. Three case studies are discussed: strings-and-pins solutions to (i) the ellipse construction problem; (ii) the shortest path problem; and (iii) the angle trisection problem. Comparisons to formal solutions are drawn. Differences and similarities between the compass-and-straightedge paradigm and the strings-and-pins paradigm are analyzed. Features and limitations of constructive and depictive geometry as well as implications for computational approaches are discussed. The strings-and-pins domain is shown to be more general and less restrictive than the compass-and-straightedge domain.     

封闭水域内固体火箭发动机尾流结构数值研究

为了研究固体火箭发动机在封闭水域中工作时尾流场特性参数变化规律,建立三维空间模型,忽略重浮力等体积力及燃气与水之间的换热传质,采用Realizable k-ε湍流模型与VOF(Volume of fluid)多相流模型,针对试验水箱内固体发动机在不同水深条件下的工作过程进行数值模拟,获得尾流流场燃气射流形貌,以及水箱壁...     

A two-stage approach for managing actuators redundancy and its application to fault tolerant flight control

In safety-critical systems such as transportation aircraft, redundancy of actuators is introduced to improve fault tolerance. How to make the best use of remaining actuators to allow the system to continue achieving a desired operation in the presence of some actuators failures is the main subject of this paper. Considering that many dynamical systems, including flight dynamics of a transportation aircraft, can be expressed as an input affine nonlinear system, a new state representation is adopted here where the output dynamics are related with virtual inputs associated with the intended operation. This representation, as well as the distribution matrix associated with the effectiveness of the remaining operational actuators, allows us to define different levels of fault tolerant governability with respect to actuators’ failures. Then, a two-stage control approach is developed, leading first to the inversion of the output dynamics to get nominal values for the virtual inputs and then to the solution of a linear quadratic(LQ) problem to compute the solicitation of each operational actuator. The proposed approach is applied to the control of a transportation aircraft which performs a stabilized roll maneuver while a partial failure appears. Two fault scenarios are considered and the resulting performance of the proposed approach is displayed and discussed.     

基于可满足性问题求解器的星上FPGA永久损伤容错技术研究

现代卫星广泛使用的FPGA在空间高能粒子的影响下,会产生门电路的永久性损伤。而传统的三模冗余等容错方法不但成倍增加了系统硬件开销,还存在因冗余器件耗尽而失效的风险。因此,提出一种利用FPGA自身冗余资源,修复永久性损伤的容错方案。该方案通过建立FPGA内部资源的功能模型,将容错问题转化为数学上的可满足性问题。并且利用经过改进的GSAT算法对该问题求解,可以获得在功能上与损伤前完全相同的电路结构,及其所对应的FPGA配置文件。将该文件重新下载到FPGA中,可以屏蔽损伤带来的影响,从而达到利用FPGA自身冗余资源容错的目的。通过实验和分析可以看出,本文方案具有对损伤修复成功率高、计算量小和需要内存空间少的特点,因此符合星上计算能力和硬件资源十分有限的实际情况。     

目标跟踪多智能体一致控制

研究了二阶多智能体系统跟踪一致问题。针对相对速度信息未知的网络,分析了有时滞和无时滞情况下网络的稳定性,给出了系统能够实现跟踪一致的条件。最后,通过仿真表明所提协议比现有协议性能更好。