Mechanical study on initial profile solution for inflatable reflector made of orthotropic material

The woven fabric membrane materials are widely used in space and terrestrial inflatable reflectors. However the material?s anisotropy makes the design analysis more complex. The deviation from the desired shape, so-called “W-profile error”, influences the precision of the membrane surface significantly. In this study, a model of an axisymmetric paraboloid surface using membrane theory is established for the purpose of facilitating the surface precision optimization. Analytical solutions for displacements of the reflector are derived. An iteration method of initial reflector profile solution is stated and a finite element (FE) software employed in the solution is presented. A case study is illustrated to make a comparison between numerical and theoretical analyses. Finally, the conclusions are drawn that the analytical method and the FE iterative method for initial profile solution are feasible and efficient.     

存款保险制度的博弈分析

银行业在一国经济活动中具有特殊地位,银行破产将会给一国的经济发展造成很大的负面效应,有效防范和化解金融风险是一国金融体系稳定运行的重要保证。本文从博弈论的角度来分析存款保险制度的作用, 指出存款保险制度有利于银行业的稳定和系统性金融风险的化解。     

The gauge-generalized Gyldén–Meshcherskii Problem

The Gyldén–Meshcherskii Problem (GMP) extends the classical two-body problem of Newton and Kepler by considering time-varying gravitating masses, an important extension of the two-body problem for modeling cometary motion and cosmological phenomena. In this paper, we consider the GMP in a specialized setup, the setup of gauge theory. We show that the variational equations, modeling the effect of the mass time variation on the orbital elements, can be derived by fixing a gauge of a particular form that is different from the Lagrange gauge. Thus, the orbital elements modeling the effect of a time-varying secondary mass are non-osculating. This implies that the trajectory of a celestial body whose mass is continuously changing cannot be approximated by a series of Keplerian orbits. Finally, we provide the first-order averaged equations written in terms of non-osculating elements.     

神经网络在R＆D项目中止决策中的应用

在比较研究国内外Ｒ＆Ｄ项目中止决策理论方法在基础上，论述了对正在进行的Ｒ＆Ｄ项目进行正确的中止决策模式识别的重要意义。探讨了神经网络（ＮＮ）理论用于Ｒ＆Ｄ项目中止决策的可行性，提出了适用于正在进行的Ｒ＆Ｄ项目的中止决策分析的Ｈｏｐｆｉｅｌｄ神经网络模式识别方法，并用实例验证了方法的有效性。方法的实施较为方便、计算较为简单，结果也令人满意。表明Ｈｏｐｆｉｅｌｄ神经网络模式识别方法在Ｒ＆Ｄ项目中止决策     

Improved local amplification factor transport equation for stationary crossflow instability in subsonic and transonic flows

Transition prediction is a hot research topic of fluid mechanics. For subsonic and transonic aerodynamic flows, e^N method based on Linear Stability Theory (LST) is usually adopted reliably to predict transition. In 2013, Coder and Maughmer established a transport equation for Tollmien-Schlichting (T-S) instability so that the e^N method can be applied to general Reynolds-Average-Navier-Stokes (RANS) solvers conveniently. However, this equation focuses on T-S instability, and is invalid for crossflow instability induced transition which plays a crucial role in flow instability of three-dimensional boundary layers. Subsequently, a transport equation for crossflow instability was developed in 2016, which is restricted to wing-like geometries. Then, in 2019, this model was extended to arbitrarily shaped geometries based on local variables. However, there are too many tedious functions and parameters in this version, and it can only be used for incompressible flows. Hence, in this paper, after a large amount of LST analyses and parameter optimization, an improved version for subsonic and transonic boundary layers is built. The present improved model is more robust and more concise, and it can be applied widely in aeronautical flows, which has great engineering application value and significance. An extensive validation study for this improved transition model will be performed.     

Some comments on the F ring-Prometheus–Pandora environment

The system formed by the F ring and two close satellites, Prometheus and Pandora, has been analysed since the time that Voyager visited the planet Saturn. During the ring plane crossing in 1995 the satellites were found in different positions as predicted by the Voyager data. Besides the mutual effects of Prometheus and Pandora, they are also disturbed by a massive F ring. Showalter et al. [Icarus 100 (1992) 394] proposed that, the core of the ring has a mass which corresponds to a moonlet varying in size from 15 to 70 km in radius which can prevent the ring from spreading due to dissipative forces, such as Poynting–Robertson drag and collisions. We have divided this work into two parts. Firstly we analysed the secular interactions between Prometheus–Pandora and a massive F ring using the secular theory. Our results show the variation in eccentricity and inclination of the satellites and the F ring taking into account a massive ring corresponding to a moonlet of different sizes. There is also a population of dust particles in the ring in the company of moonlets at different sizes [Icarus 109 (1997) 304]. We also analysed the behaviour of these particles under the effects of the Poynting–Robertson drag and radiation pressure. Our results show that the time scale proposed for a dust particle to leave the ring is much shorter than predicted before even in the presence of a coorbital moonlet. This result does not agree with the confinement model proposed by Dermott et al. [Nature 284 (1980) 309]. In 2004, Cassini mission will perform repeated observations of the whole system, including observations of the satellites and the F ring environment. These data will help us to better understand this system.     

寿命为爱尔兰分布的可修机器服务模型分析(英文)

涉及一类可修机器服务模型,其服务设备寿命为K阶爱尔兰分布且可修复如新,并给出该系统稳态下的循环时间和若干可靠性指标.     

"三方对决"中的策略选择

应用博弈论中优势策略的概念和概率的计算方法，通过计算三方的生存概率，讨论了博弈论中的三方对决问题，并通过社会、经济、教育、政治等活动中的事例，介绍了它的部分应用，对处在激烈竞争环境中的个人或组织如何选择对策具有一定的启示。     

Initial design of laboratories for sustainable habitation

An effective and self-sustainable artificial habitat design is essential for human spaceflight and expansion of mankind into orbit or towards other celestial bodies. There are two approaches that need to be implemented in future sustainable habitats: the use of re-cycling technologies in order to gain experience in closed-loop processes and the primary production of resource materials using In Situ Resource Utilisation (ISRU) principles. Various products will be provided and, where applicable, recycled in such a system taking into account basic human factors requirements such as crew work load capacity, safety and well-being, namely:     

一种有效的粗大误差判别方法

提出了一种以灰色系统理论为基础的粗大误差判别方法，该方法对测量数据少或者难于寻求统计规律的测量过程尤为有效，与算术平均滤波法一起使用可以提高数据处理的效率。理论分析和测试结果表明，采用上述的数据处理方法可以有效地提高测量系统的测量精度和测量效率。