Oblique sounding of the ionosphere by powerful wave beams

The article is devoted to modeling the impact on the ionosphere powerful obliquely incident wave beam. The basis of this analysis will be orbital variational principle for the intense wave beams-generalization of Fermat’s principle to the case of a nonlinear medium (, ,  and ). Under the influence of a powerful wave beam appears manageable the additional stratification of the ionospheric layer F2. Explicit expressions show how the properties of the test beam, with a shifted frequency, released in the same direction as the beam depend on the intensity of a powerful beam and the frequency shift.     

一种求解轨迹优化问题的改进多分辨率技术

针对轨迹优化多分辨率技术可能发生细化遗漏或者细化失败的缺陷，设计了一种改进多分辨率技术。该方法通过在每次网格细化迭代过程中增加两层高分辨率节点并且引入节点检测算法，确保在轨迹的非光滑区域能够高效、持续地细化网格。针对原始多分辨率技术的初始网格的节点数目存在二进限制的弊端，定义了一种新的广义二分网格，使得多分辨率技术的初始网格节点数目可以为任意奇数。采用多个轨迹优化算例验证了本文方法的有效性并且与其它方法进行了对比。此外，仿真结果还表明，网格充分细化对目标函数影响不大，但是能够更加准确地满足路径约束和终端状态约束。     

组合动力运载器上升段轨迹智能优化方法

针对组合动力水平起飞可重复使用运载器，开展了上升段轨迹优化模型设计与轨迹优化方法研究。首先，针对跨大空/速域飞行须采用多种动力形式协调工作这一问题，考虑动力/气动/轨迹/指标间的复杂耦合关系，建立了运载器动力和气动模型。其次，为降低轨迹优化问题的求解难度，设计了一种全新的飞行剖面，实现了关键优化参数的提取和攻角约束的自动满足，减少了优化算法需要处理的约束数量。然后，提出了一种改进的粒子群优化(PSO)算法完成求解；在收敛性分析的基础上，引入强化学习机制对PSO寻优过程进行自主智能控制，从本质上提升了PSO算法的求解效率。最后通过数学仿真验证了方法的正确性和有效性。     

基于轨迹规划的飞机发动机数字化安装技术研究

提出了基于视觉的发动机数字化安装系统的设计方案,运用齐次坐标变换进行了发动机在笛卡尔空间的离线轨迹规划,阐述了基于图像低秩矩阵复原的发动机位姿测量算法,提出了基于视觉的发动机在线轨迹规划方法。进行了发动机安装试验,试验结果表明,这种新型的数字化安装技术具有很好的稳定性、高效性和精确性。     

水下目标定位ST系统的测量原理

根据ST系统测量设备空间布局的几何关系,推导出了该系统的观测方程,建立了水下目标运动轨迹测量的数学模型,并对模拟的目标运动轨迹进行了定位精度的仿真计算。     

飞行器阵风响应的CFD-6DOF仿真分析

飞行器在大气中飞行,不可避免地受到阵风的影响。阵风所附加的气动载荷引发飞行器飞行状态的改变,过大幅值的阵风影响飞行的性能与安全。针对这种状况,首先采用改进的Lamb-Ossen涡模型,建立尾涡形式的阵风场;然后采用基于CFD技术的非定常N-S方程求解,并在计算网格中引入"网格速度"来模拟阵风,对SWIM(Subsonic Wall Interference Model)尾涡中的定常气动特性进行验证;最后通过CFD-6DOF的耦合,对SWIM俯冲穿越尾涡场的飞行轨迹进行研究。结果表明:计算结果与实验值符合较好;SWIM在尾涡中飞行时出现抖动、下沉、改变飞行状态、剧烈翻转的现象,与实际飞行器进入尾涡中的轨迹特性类似。     

Optimal control laws for heliocentric transfers with a magnetic sail

A magnetic sail is an advanced propellantless propulsion system that uses the interaction between the solar wind and an artificial magnetic field generated by the spacecraft, to produce a propulsive thrust in interplanetary space. The aim of this paper is to collect the available experimental data, and the simulation results, to develop a simplified mathematical model that describes the propulsive acceleration of a magnetic sail, in an analytical form, for mission analysis purposes. Such a mathematical model is then used for estimating the performance of a magnetic sail-based spacecraft in a two-dimensional, minimum time, deep space mission scenario. In particular, optimal and locally optimal steering laws are derived using an indirect approach. The obtained results are then applied to a mission analysis involving both an optimal Earth–Venus (circle-to-circle) interplanetary transfer, and a locally optimal Solar System escape trajectory. For example, assuming a characteristic acceleration of 1 mm/s², an optimal Earth–Venus transfer may be completed within about 380 days.     

空天飞行器制导控制技术研究进展与展望

本文在简要介绍空天飞行器制导控制技术发展情况基础上，针对其典型的任务形态给制导控制技术带来的挑战，分别从动力学建模、轨迹优化与制导、飞行控制与导航等四个方面阐述了制导控制技术中面临的关键技术，并探讨了空天飞行器制导控制技术后续发展方向与思路。     

Ascent trajectory optimization for stratospheric airship with thermal effects

Ascent trajectory optimization with thermal effects is addressed for a stratospheric airship. Basic thermal characteristics of the stratospheric airship are introduced. Besides, the airship’s equations of motion are constructed by including the factors about aerodynamic force, added mass and wind profiles which are developed based on horizontal-wind model. For both minimum-time and minimum-energy flights during ascent, the trajectory optimization problem is described with the path and terminal constraints in different scenarios and then, is converted into a parameter optimization problem by a direct collocation method. Sparse Nonlinear OPTimizer(SNOPT) is employed as a nonlinear programming solver and two scenarios are adopted. The solutions obtained illustrate that the trajectories are greatly affected by the thermal behaviors which prolong the daytime minimum-time flights of about 20.8% compared with that of nighttime in scenario 1 and of about 10.5% in scenario 2. And there is the same trend for minimum-energy flights. For the energy consumption of minimum-time flights, 6% decrease is abstained in scenario 1 and 5% decrease in scenario 2. However, a few energy consumption reduction is achieved for minimum-energy flights. Solar radiation is the principal component and the natural wind also affects the thermal behaviors of stratospheric airship during ascent. The relationship between take-off time and performance of airship during ascent is discussed. it is found that the take-off time at dusk is best choice for stratospheric airship. And in addition, for saving energy, airship prefers to fly downwind.     

组合发动机系统控制方程（1）

本文给出了一组能够描述各种组合发动机系统工作过程的通用方程组。在火箭运动的仿真计算时，此组方程是非常有用的。现已使用于弹道计算通用程序包ＴＣ系列中。从而使得通用程序包ＴＣ可以方便而准确地对各种类型的火箭与空间飞行器的弹道进行仿真。