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Low-thrust trajectory optimization for multiple target bodies tour mission

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Theoretical & Applied Mechanics Letters 2011年第5期1卷 77-80页

作者： Hongxin Shen,Jianping Zhou,Qibo Peng,Yazhong luo,and Haiyang Li college of aerospace and material engineering,national university of defense technology,changsha 410073,china college of aerospace and material engineering National University of Defense Technology Changsha 410073 China

Spacecraft science missions to planets or asteroids have historically visited only one or several celestial bodies per *** research goal of this paper is to create a trajectory design algorithm that generates trajectory allowing a spacecraft to visit a significant number of asteroids during a single *** the problem of global trajectory optimization,even with recent advances in low-thrust trajectory optimization,a full enumeration of this problem is not *** work presents an algorithm to traverse the searching space in a practical fashion and generate *** flight sequence is determined in ballistic scenario,and a differential evolution method is used with constructing a three-impulse transfer problem,then the local optimization is implemented with low-thrust propulsion on the basis of the solutions of impulsive *** proposed method enables trajectory design for multiple asteroids tour by using available low thrust propulsion technology within fuel and time duration constraints.

关键词： global optimization low-thrust differential evolution direct shooting

Artificial frozen orbit control scheme based on J_2 perturbation

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Science china(Technological Sciences) 2010年第11期53卷 3138-3144页

作者： WANG GongBo meng yunhe ZHENG Wei tang guojian college of aerospace and material engineering National University of Defense TechnologyChangsha 410073China

Since the inclination of frozen orbit with non-rotation of the perigee that occurs due to J2 perturbation must be equal to the critical inclination, this regulation has restricted the application of frozen orbit a lot. In this paper, we propose two control strategies to eliminate the secular growth of the argument of the perigee for orbits that are not at the critical inclination. One control strategy is using transverse continuous low-thrust, and the other is using both the transverse and the radial continuous low-thrusts. Fuel optimization in the second control strategy is addressed to make sure that the fuel consumption is the minimum. Both strategies have no effect on other orbital parameters’ secular motion. It is proved that the strategy with transverse control could save more energy than the one with radial control. Simulations show that the second control strategy could save 54.6% and 86% of energy, respectively, compared with the two methods presented in the references.

关键词： continuous low-thrust artificial frozen orbit Gauss’variation of parameters equations mean element method

Experimental technique based on delay phase of PZT vibrator and flow-field of PZT-driven dual synthetic jets actuator

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Experimental technique based on delay phase of PZT vibrator ...

2011年全国压电和声波理论及器件应用研讨会

作者： Zhen-bing luo~* Xiong DENG Lin WANG Zhi-xun XIA college of aerospace and material engineering,national university of defense technology,changsha 410073

＜正＞There is a delay phase angle between the displacement signal and voltage signal of PZT-driven *** higher the driving frequency,the larger delay phase angle of the PZT vibrator will *** on the delay phase angle o... 详细信息

关键词： Experimental technique Delay phase PZT vibrator Flow-field Dual synthetic jet actuator

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高维复杂函数的混合模拟退火全局优化策略

计算机工程与应用 2004年第23期40卷 36-39页

作者：王忠贵罗亚中国防科技大学航天与材料工程学院中国载人航天工程办公室北京10008

对于高维复杂函数优化问题,经典的优化算法存在着初始点敏感、局部收敛等问题;而模拟退火算法等智能算法则有着计算成本高昂、算法早熟等缺陷。NFL定理犤1犦预示了混合优化策略是解决实际优化问题的最好途径。该文融合了模拟退火算法和... 详细信息

对于高维复杂函数优化问题,经典的优化算法存在着初始点敏感、局部收敛等问题;而模拟退火算法等智能算法则有着计算成本高昂、算法早熟等缺陷。NFL定理犤1犦预示了混合优化策略是解决实际优化问题的最好途径。该文融合了模拟退火算法和经典算法的优点,设计了高维复杂函数混合模拟退火优化策略。混合优化策略具有模拟退火算法的全局收敛性,同时引入强局部收敛经典算法作为模拟退火算法的精英个体提高算子,提高了模拟退火算法局部开采能力,加快了收敛速度。数值仿真计算结果表明,混合模拟退火策略求解高维复杂函数的性能大大优于单一算法,具有强鲁棒性、高收敛速度和高精度等优点。该文的算法设计思想对于解决实际问题有较好的借鉴意义。

关键词：高维复杂函数混合全局优化模拟退火算法 NFL定理精英策略

Multi-material Topology Optimization of 2D Structures Using Convolutional Neural Networks

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Computer Modeling in engineering & Sciences 2024年第8期140卷 1919-1947页

作者： Jiaxiang luo Weien Zhou Bingxiao Du Daokui Li Wen Yao college of aerospace Science and engineering National University of Defense TechnologyChangsha410073China defense Innovation Institute Chinese Academy of Military ScienceBeijing100071China Intelligent Game and Decision Laboratory Chinese Academy of Military ScienceBeijing100071China

In recent years,there has been significant research on the application of deep learning(DL)in topology optimization(TO)to accelerate structural ***,these methods have primarily focused on solving binary TO problems,and effective solutions for multi-material topology optimization(MMTO)which requires a lot of computing resources are still ***,this paper proposes the framework of multiphase topology optimization using deep learning to accelerate MMTO *** framework employs convolutional neural network(CNN)to construct a surrogate model for solving MMTO,and the obtained surrogate model can rapidly generate multi-material structure topologies in negligible time without any *** performance evaluation results show that the proposed method not only outputs multi-material topologies with clear material boundary but also reduces the calculation cost with high prediction ***,in order to find a more reasonable modeling method for MMTO,this paper studies the characteristics of surrogate modeling as regression task and classification *** the training of 297 models,our findings show that the regression task yields slightly better results than the classification task in most ***,The results indicate that the prediction accuracy is primarily influenced by factors such as the TO problem,material category,and data ***,factors such as the domain size and the material property have minimal impact on the accuracy.

关键词： Multi-material topology optimization convolutional neural networks deep learning finite element analysis

Investigation on single-star stellar-inertial guidance principle using equivalent information compression theory

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Science china(Technological Sciences) 2009年第10期52卷 2924-2929页

作者： ZHANG HongBo ZHENG Wei WU Jie tang guojian college of aerospace and material engineering National University of Defense TechnologyChangsha 410073China

Stellar-inertial guidance is a composite guidance technique that can effectively enhance the impact accuracy of ballistic missiles. In this paper, measurement and correction equations for a single-star stellar-inertial guidance system were developed, and a concept of equivalent information compression was presented and discussed through some propositions. With this concept, accuracies of single/double star schemes were compared, and it was shown that a single-star scheme can achieve the accuracy equivalent to a double-star scheme. This theoretically proves the feasibility of the rapid determination of the optimum stellar direction of the single-star scheme. Lastly, a compensational method to correct the guidance errors was employed when the adopted navigation star deviated from the optimum stellar direction.

关键词： stellar guidance equivalent information compression single-star guidance scheme optimum stellar direction

Research on the strategy of angles-only relative navigation for autonomous rendezvous

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Science china(Technological Sciences) 2011年第7期54卷 1865-1872页

作者： LI JiuRen LI HaiYang tang GuoJin luo YaZhong college of aerospace and material engineering National University of Defense Technology Changsha 410073 China

This paper considers the problem of angles-only relative navigation for autonomous rendezvous. Methods for determining degree of observability （DO0） and latent range information of orbital maneuver are proposed for analyzing and enhancing the precision of relative position and velocity estimation. The equations of angles-only relative navigation are set forth on the con- dition that optical camera is the only viable sensor for relative measurement, and expressions for the DO0 of relative navigation are obtained by using the Newton iterative method. The latent range information of orbital maneuver is analyzed, which is employed to enhance the DOO of angles-only relative navigation. Simulation result shows that DOO is effective to describe the observability level of relative position and velocity, and the latent range information is useful in enhancing the DOO of the angles-only relative navigation.

关键词： autonomous rendezvous relative navigation angles-only degree of observability orbital maneuver

逆向射流对高超声速升力体构型的减阻特性研究

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宇航学报 2024年第6期45卷 881-892页

作者：王林王宇楠罗振兵周岩谢玮刘强国防科技大学空天科学学院长沙410073

在高超声速飞行过程中,飞行器往往会面临巨大的阻力,严重限制了其飞行性能,并增加了飞行器表面的热负荷和材料应力。针对这一问题,通过数值模拟系统地分析了射流孔数量、位置和攻角对升力体减阻性能的影响。研究结果表明,随着射流孔数... 详细信息

在高超声速飞行过程中,飞行器往往会面临巨大的阻力,严重限制了其飞行性能,并增加了飞行器表面的热负荷和材料应力。针对这一问题,通过数值模拟系统地分析了射流孔数量、位置和攻角对升力体减阻性能的影响。研究结果表明,随着射流孔数量的增加,整体减阻率显著提高,有效降低了升力体头部的高压区域,但也导致四周流场的不稳定性增强。射流孔位置对激波脱体距离和“气膜”厚度具有重要影响。此外,增大攻角会导致整体减阻率下降,但对局部减阻率影响较小,同时会增加上下壁面之间的压差。进一步比较研究发现,在20 km和55 km高空条件下,这3种因素对减阻性能的影响规律保持一致。研究结果为设计高效减阻方案提供了重要参考。

关键词：逆向射流减阻升力体高超声速飞行器激波

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对位芳纶的结构与缺陷对其力学性能的影响

东华大学学报（自然科学版） 2024年第4期50卷 76-82页

作者：路慧颖唐凯雒瑞银张建红刘书杰于宏广林威宏王忠伟杜志林滕翠青东华大学材料科学与工程学院纤维材料改性国家重点实验室上海宁夏泰和芳纶纤维有限责任公司宁夏回族自治区银川泰和新材集团股份有限公司山东烟台

聚对苯二甲酰对苯二胺(PPTA)纤维具有优异的力学性能、耐化学腐蚀性能以及阻燃性能,在航空航天、国防、民用等领域得到了广泛应用,是一种新型战略性材料。对4种不同规格的对位芳纶的力学性能、相对分子质量、聚集态结构以及纤维表面及... 详细信息

聚对苯二甲酰对苯二胺(PPTA)纤维具有优异的力学性能、耐化学腐蚀性能以及阻燃性能,在航空航天、国防、民用等领域得到了广泛应用,是一种新型战略性材料。对4种不同规格的对位芳纶的力学性能、相对分子质量、聚集态结构以及纤维表面及内部缺陷进行研究,建立纤维结构、缺陷与性能之间的关系。结果表明:在具有相同化学分子结构的前提下,聚合物相对分子质量是影响纤维力学性能的重要因素之一,随着相对分子质量的增加,纤维的强度和模量增加。对位芳纶的拉伸强度主要与其结晶度、取向度、表面缺陷以及内部微孔缺陷有关,其中结晶度和微孔缺陷最为重要。纤维的模量主要与纤维的取向度有关,结晶度及纤维内外部缺陷对纤维模量的影响较小。

关键词：聚对苯二甲酰对苯二胺(PPTA)纤维相对分子质量聚集态结构缺陷力学性能