航天器再入制导方法综述

航天器再入制导方法国内外已有不少的学者进行了研究。本文对国内学者这方面的工作作一综述。目前国内研究的大多为有标准轨道的再入制导方法，且从最优原理出发对再入标准轨道进行了优化。对纵向再入制导规律也找出了最佳增益系数。侧向制导采用漏斗型开关曲线其效果良好。预测制导方法也开始了研究工作。     

公共选修课教学策略的优化整合——以古诗词欣赏为例

采用教学原理,从教学准备、主要教学行为、课堂管理行为、教学评价四个方面对公共选修课课堂教学策略进行优化整合,为公共选修课设计出一套切实可行的课堂教学策略。     

我国税制结构的优化

随着经济的发展和税源结构的变化，税制结构的调整显得十分必要和紧迫，笔者分析了制约我国税制结构优化的因素、税制结构优化的标准，现行税制结构中存在的主要问题，并对优化我国税制结构的措施提出了具体看法。     

Rapid model-based inter-disciplinary design of a CubeSat mission

With an increase in the use of small, modular, resource-limited satellites for Earth orbiting applications, the benefit to be had from a model-based architecture that rapidly searches the mission trade-space and identifies near-optimal designs is greater than ever. This work presents an architecture that identifies trends between conflicting objectives (e.g. lifecycle cost and performance) and decision variables (e.g. orbit altitude and inclination) such that informed assessment can be made as to which design/s to take on for further analysis. The models within the architecture exploit analytic methods where possible, in order avoid computationally expensive numerical propagation, and achieve rapid convergence. Two mission cases are studied; the first is an Earth observation satellite and presents a trade-off between ground sample distance and revisit time over a ground target, given altitude as the decision variable. The second is a satellite with a generic scientific payload and shows a more involved trade-off, between data return to a ground station and cost of the mission, given variations in the orbit altitude, inclination and ground station latitude. Results of each case are presented graphically and it is clear that non-intuitive results are captured that would typically be missed using traditional, point-design methods, where only discrete scenarios are examined.     

结构比强度及其在优化设计中的应用

本文从结构重量角度推导了比强度(含比模量)表达式,分析了对同一材料不同比强度的关系,给出了比强度在结构动态分析中及结构优化设计中的应用。     

热流限制下的最优气动力辅助变轨

以变轨能量消耗最小为优化目标，应用极大值原理研究了飞行过程受热流限制和升力系统约束下的气动力辅助共面变轨问题，飞行过程成分第一自由弧段，约束弧段，第二自由弧段三个部分，讨论了升力系数的最优表达式，分析了飞行过程中两种约束的相互作用，给出了约束弧起始位置的角点条件和终端的横截条件下，对不同的初值选取方法讨论了三种计算策略，并给出了数值算例。     

Aerodynamic optimization design for high pressure turbines based on the adjoint approach

A first study on the continuous adjoint formulation for aerodynamic optimization design of high pressure turbines based on S2surface governed by the Euler equations with source terms is presented.The objective function is defined as an integral function along the boundaries,and the adjoint equations and the boundary conditions are derived by introducing the adjoint variable vectors.The gradient expression of the objective function then includes only the terms related to physical shape variations.The numerical solution of the adjoint equation is conducted by a finitedifference method with the Jameson spatial scheme employing the first and the third order dissipative fluxes.A gradient-based aerodynamic optimization system is established by integrating the blade stagger angles,the stacking lines and the passage perturbation parameterization with the quasi-Newton method of Broyden–Fletcher–Goldfarb–Shanno(BFGS).The application of the continuous adjoint method is validated through a single stage high pressure turbine optimization case.The adiabatic efficiency increases from 0.8875 to 0.8931,whilst the mass flow rate and the pressure ratio remain almost unchanged.The optimization design is shown to reduce the passage vortex loss as well as the mixing loss due to the cooling air injection.     

Enhancing buckling capacity of a rectangular plate under uniaxial compression by utilizing an auxetic material

Auxetic materials have previously been shown to enhance various performances due to its unusual property of becoming fatter when uniaxially stretched and thinner when uniaxially com-pressed (i.e., the materials exhibit a negative Poisson’s ratio). The current study focuses on assessing the potential of an auxetic material to enhance the buckling capacity of a rectangular plate under uniaxial compression. The in-plane translational restraint along the unloaded edges that was often neglected in open literature is taken into consideration in our buckling model proposed in this study. The closed-form expressions for the critical buckling coefficient of the rectangle are provided and the predicted results agree well with those determined by the finite element method. Further-more, the results indicate that the buckling performance of a rectangular plate under uniaxial com-pression can be significantly improved by replacing the traditional material that has a positive Poisson’s ratio with an auxetic material when there is in-plane translation restraint along the unloaded edges.     

An optimal microsatellite system for optical remote sensing data management

Inter-Satellite Link represents an innovative aspect in remote sensing missions, allowing the exchange of data between satellites of a constellation according to appropriate algorithms for the minimization of the delivery time of requested data. In a recent study, the feasibility of gaining a long period of Inter-Satellite Link with an acceptable level of Bit Error Rate has been demonstrated by using a Walker Constellation composed of 20 micro-satellites located on Sun-Synchronous Orbits. In this paper, an investigation into the performance of such a constellation through the implementation of an optimal process of target access and data exchange among satellites has been carried out, together with a sizing of the onboard telecommunication system. A process analysis has been executed through the modelling of weighted fitting functions, specific for an optical remote sensing system.     

M40/4211 复合材料层合板铣削加工试验

通过分析碳纤维复合材料的性能特点及对切削加工性能的影响,提出了铣削刀具材料和几何结构形式的选用原则,介绍了几种适于碳纤维复合材料铣削的加工刀具。针对碳纤维复合材料中常用的M40/4211复合材料层合板进行加工缺陷试验和切削试验,总结出影响M40/4211复合材料层合板加工质量的因素及规律,得到每种刀具加工M40/4211复合材料层合板的最佳加工参数,较高的切削速度配合恰当的进给速度可以有效提高M40/4211复合材料层合板的加工质量和加工效率。