Topology optimization in lightweight design of a 3D-printed flapping-wing micro aerial vehicle

Topology optimization is an effective method to obtain a lightweight structure that meets the requirements of structural strength. Whether the optimization results meet the actual needs mainly depends on the accuracy of the material properties and the boundary conditions, especially for a tiny Flapping-wing Micro Aerial Vehicle (FMAV) transmission system manufactured by 3D printing. In this paper, experimental and numerical computation efforts were undertaken to gain a reliable topology optimization method for the bottom of the transmission system. First, the constitutive behavior of the ultraviolet (UV) curable resin used in fabrication was evaluated. Second, a numerical computation model describing further verified via experiments. Topology optimization modeling considering nonlinear factors, e.g. contact, friction and collision, was presented, and the optimization results were verified by both dynamic simulation and experiments. Finally, detailed discussions on different load cases and constraints were presented to clarify their effect on the optimization. Our methods and results presented in this paper may shed light on the lightweight design of a FMAV.     

An innovative approach for integrated airline network and aircraft family optimization

The determination of optimal aerial transport networks and their associated flight frequencies is crucial for the strategic planning of airlines, as well as for carrying out market research, to establish target markets, and for aircraft and crew rostering. In addition, optimum airplane types for the selected networks are crucial to improve revenue and to provide reduced operating costs. The present study proposes an innovative approach to determine the optimal aerial transport network simultaneously with the determination of the optimum fleet for that network, composed of three types of airplanes (network and vehicle integrated design). The network profit is maximized. The passenger’s demands between the airports are determined via a gravitational model. An embedded linear programming solution is responsible for obtaining potential optimal network configurations. The optimum fleet combination is determined from a database of candidate aircraft designs via genetic algorithm. A truly realistic airplane representation is made possible thanks to accurate surrogate models for engine and aerodynamics is adopted. An accurate engine deck encompassing a compression map and an innovative engine weight calculation besides an aerodynamical artificial neural network module enable a high degree of accuracy for the mission analysis. The proposed methodology is applied to obtain the optimum network comprised of twenty main Brazilian airports and corresponding fleet.     

一种基于多点测距信息的复合制导方法

分析探讨了一种用于提高弹道式导弹对目标命中精度的复合制导方案，提出了通过进行多点测距，利用状态转移矩阵方法，来估计导弹落点偏差和末修级起控点飞行状态参数，然后再按照需要的速度进行末修级导引控制的复合制导方案，并通过仿真计算分析论证了该方法的可行性。     

关于疲劳裂纹扩展数学模型的参数寻优

本文通过引入工程设计中的优化方法，分别对室内空气环境下铝合金（ＬＹ１２－ＣＺ）材料疲劳裂纹扩展的数学模型，以及环境条件下（３．５％ＮａＣｌ水溶液浸泡）该材料腐蚀疲劳裂纹扩展的数学模型进行了探讨。在已知标准试样在不同的环境下疲劳裂纹扩展实验ｄａｄＮｉ，ΔＫｉ的条件下，采用优化方法进行参数寻优，可方便地得到与其对应的疲劳裂纹扩展的ｄａｄＮ～ΔＫ最优数学模型     

图样的知识目标分类与例证性分析

根据教育目标分类学的观点分解课程教学目标，再分别对分解的目标进行例证性分析，能更客观地验证教育目标的实效性和教育过程的可行性。本文通过对图样的知识目标分类与例证性分析，为工程图学教育目标检测做一尝试。     

满足约束的Gn连续过渡曲面的构造

在Erich Hartmann提出的由两基曲面线性组合构造G^n连续过渡曲面方法的基础上，针对该方法存在很难找到合适的参数变换的问题，提出了一种基于基曲面局部区域重新参数化构造G^n连续过渡曲面的方法。通过对基曲面上切触线附近区域部分曲面重新参数化，再由重新参数化局部基曲面线性组合构造G^n连续过渡曲面。这样将两基曲面间构造过渡曲面的问题转化为在重新参数化局部基曲面间构造过渡曲面。以构造G^1连续的翼身融合面为例，讨论了满足约束要求条件时G^2连续过渡面的构造方法。即先对基曲面上过渡切触线附近的局部区域进行重新参数化，后通过优化求解来确定比例因子和偏移量、平衡因子和调配因子，使过渡曲面满足前后边条线约束，最后利用线性组合来构造G^2连续的过渡面。约束过渡曲面的形状可通过改变重新参数化基曲面的大小来调整．     

国际贸易中标准问题解决方略的研究

国际贸易中的标准问题是产生贸易壁垒的一个很重要的方面,世贸组织虽然为解决这一问题做出了一些规定,采取了一些措施,但是实际效果并不好,很多的成员国并没遵守有关的规则,兑现各自的承诺。而且随着世界经济区域集团化,各种区域性标准在对内起到保护作用的同时,对外则建起新的贸易保护障碍。解决国际贸易中的标准问题,应该从两方面着手,一是加强双边合作,二是加强多方位合作。双边合作是解决标准问题直接而有效的途径,随着贸易的全球化发展,标准统一化是最终的趋势。     

Broad-band spectral properties of accreting X-ray binary pulsars

Broad-band spectra of accreting X-ray binary pulsars can be fitted by a phenomenological model composed of a power law with a high energy rollover above 10 keV, plus a blackbody component with a temperature of few hundred eV. While, at least qualitatively, the hard tail can be explained in terms of (inverse) Compton scattering, the origin of the soft component cannot find a unique explanation. Recently, a qualitative picture able to explain the overall broad-band spectrum of luminous X-ray pulsars was carried out by taking into account the effect of bulk Comptonization in the accretion column. After a review of these recent theoretical developments, I will present a case study of how different modeling of the continuum affect broad features, in particular the cyclotron resonance features in Vela X-1.     

关于加大产业结构调整力度的思考

本文从我国产业结构调整的现状及存在的问题出发，针对一般加工产业生产能力过大，高水平的加工能力不足这一突出问题进行了原因分析，在此基础上，就我国加速优化产业结构的客观基础和可能，提出了关于加大产业结构调整力度的七点思考建议。     

反射面的轴向电磁散射及外形优化

本文联合运用几何光学和等效电磁流法,导出了金属反射面轴向散射场和雷达截面(RCS)的简洁表达式,研究了从旋转二次曲面(凹面或凸面)中寻找具有最低RCS值的曲面形状优化方法,给出了一个典型实例的单站RCS立体分布图,以及最低RCS值所对应的波谷曲线和最佳表面参数。