某型飞机非线性动力学特性的分叉分析

针对某静不稳定飞机的非线性动力学模型，采用分叉与突变理论（BACTM）计算了常规控制面变化的飞机本体平衡曲线，揭示了其固有的在大迎角下的开环运动特性，在此基础上，设计纵向增稳系统，以保证飞机在小迎角下具有良好的操纵特性，然后再用BACTM分析预测其大迎角下的闭环运动特性，结果表明，其具有与静稳定性飞机类似的预测结果。     

Identifying vital edges in Chinese air route network via memetic algorithm

Due to rapid development in the past decade, air transportation system has attracted considerable research attention from diverse communities. While most of the previous studies focused on airline networks, here we systematically explore the robustness of the Chinese air route network, and identify the vital edges which form the backbone of Chinese air transportation system. Specifically, we employ a memetic algorithm to minimize the network robustness after removing certain edges, and hence the solution of this model is the set of vital edges. Counterintuitively, our results show that the most vital edges are not necessarily the edges of the highest topological importance, for which we provide an extensive explanation from the microscope view. Our findings also offer new insights to understanding and optimizing other real-world network systems.     

细长锥体有攻角绕流的非对称分岔及其涡结构的数值模拟

本文用ＮＮＤ格式计算了具有复杂涡结构的细长锥体有攻角绕流问题，着重研究了非对称分离的分岔现象以及分岔前后涡结构的演变，数值计算结果表明，大约在ａ／（２β）＝１．０时，Ｎ－Ｓ方程出现分岔解，同时还给出了分岔前后涡结构及物理最分布的特征。     

提高飞行器气动效益的一条技术途径

本文对人类升空奋斗史作了简要的回顾,指出人类虽然在飞行技术方面现已取得了惊天动地的成就,但有许多飞行技巧还远远不如飞鸟与昆虫;阐述了飞行器欲获得其升力的第二峰值之可能途径——对飞鸟与昆虫为获取其非定常涡升力的一些飞行奥秘作了剖析,在此基础上对当今空气动力学研究的一些方向性问題提出了一些见解,并就我国在这方面应当开展的研究工作提出了一些具体的建议。     

合并式电离—复合反应的DSMC模拟

采用ＤＳＭＣ方法研究分子碰撞反应机理,在分析水平上模拟绝热封闭体系事并式电离－复合反应的驰豫过程。     

三维效应对轴流压气机气动稳定性的影响

轴流压气机的气动稳定性模型,最初为一维模型,仅适用于描述喘振发作.对于旋转失速发作,在公开文献中有一些二维模型发表.本文提出了一类考虑压气机径向扰动对失速影响的新的气动稳定性模型.计算结果表明压气机的轴向扰动往往随着径向扰动的产生,径向扰动的强度影响压气机的气动稳定性,在叶尖还是叶根首先产生失速与压气机基元叶栅特性密切相关.本文对轴流压气机二维和三维气动稳定性模型的计算结果进行了对比分析.     

Two-level optimization approach for Mars orbital long-duration,large non-coplanar rendezvous phasing maneuvers

A relative dynamics equation-set based on orbital element differences with J₂ effects is derived, based on which a two-level approach is proposed to optimize the Mars orbital rendezvous phasing with a large difference in the initial ascending node. The up-level problem uses the revolution deviation between the target spacecraft and the chaser as the design variable, and employs a linear search to find the optimum. The low-level problem uses the maneuver revolutions, locations, and impulses as the design variables, and is solved using a hybrid genetic algorithm combined with sequential quadratic programming. To improve the solution accuracy, an iteration method is developed to satisfy the terminal constraints of the absolute numerical integration trajectory. Test cases involving Mars sample return missions with large initial node differences are presented, which show that the relative dynamics, two-level optimization model, and hybrid optimization algorithm are efficient and robust. Compared with previously published results, the total velocity increment has been further reduced by utilizing this proposed approach. It is found that a five-impulse plan requires the least quantity of propellant, and a propellant-optimal minimum rendezvous duration exists for this long-duration, large non-coplanar rendezvous problem.     

大学英语课堂文化语境建构的实践研究

语言与文化的关系密不可分,只学习语言本身,缺少对外语文化的了解已不能适应目前跨文化交际的需求。作为大学英语教师,不能忽视文化语境的教学,文化语境的建构和提高大学生跨文化交际能力正是项目的研究目的。从提高大学生跨文化交际的必要性、方法,及如何在课堂上灌输文化教学的实践基础出发,为大学英语教师适应新时代的大学英语教学提供借鉴。     

双阀座电磁阀的负载特性仿真分析

通过有限元仿真软件Ansoft建立电磁阀的物理模型,计算电磁场中各变量之间的相互关系,将分析结果导入液压仿真软件AMESim的系统模型中,实现磁路结构、液路系统及机械传动之间的耦合,对双阀座电磁阀的响应时间、质量流量等负载特性进行更精确的仿真和分析.     

Chang’E-1 precision orbit determination and lunar gravity field solution

In this paper we present results assessing the role of Very Long Baseline Interferometry (VLBI) tracking data through precision orbit determination (POD) during the check-out phase for Chang’E-1, and the lunar gravity field solution CEGM-01 based on the orbital tracking data acquired during the nominal phase of the mission. The POD of Chang’E-1 is performed using S-band two-way Range and Range Rate (R&RR) data, together with VLBI delay and delay rate observations. The role of the VLBI data in the POD of Chang’E-1 is analyzed, and the resulting orbital accuracies are estimated for different solution strategies. The final orbital accuracies proved that the VLBI tracking data can improve the Chang’E-1 POD significantly. Consequently, CEGM-01 based on six-month tracking data during Chang’E-1 nominal mission phase is presented, and the accuracy of the model is assessed by means of the gravity field power spectrum, admittance and coherence between gravity and topography, lunar surface gravity anomaly and POD for both Chang’E-1 and Lunar Prospector (LP). Our analysis indicates that CEGM-01 has significant improvements over a prior model (i.e. GLGM-2), and shows the potential of Chang’E-1 tracking data in high resolution lunar gravity field model solution by combining with SELENE and LP tracking data.