我国行星化学学科发展现状与展望

半个世纪以来,行星化学一直是欧美以及日本等主要科技强国最活跃的科学研究前沿之一。但是,由于种种限制,我国的行星化学一直没有得到充足发展。这种状况和我国的航天大国地位并不相称,也会成为我国建成航天强国目标的阻碍之一。因此,在全国各大重点院校进行行星化学学科建设迫在眉睫。基于行星化学学科对于深空探测的重要性,文章将着眼于行星化学学科的内涵,探讨行星化学学科的独特性,比较国内外学科建设的差距,提出我国行星化学学科建设的建议。     

Internationalisation,planetary citizenship and Higher Education Inc.

The internationalisation of higher education aims to produce ‘citizens that feel at home in the world’ but the process is driven by both economic and educational motivations. Today, the international community aspires to promote Education for Sustainable Development (ESD) and Education for Democratic Citizenship (EDC), together planetary citizenship, and with them emphases on personal and ethical responsibilities to the environment and future that contrast with current competitive individualism. Driven by rising numbers of international students, curricula are already shifting toward more global assessments of society and environment. However, progress is being impeded by management systems that take commerce as their model. While instructors strive to ensure that learners consider their responsibilities through ESD and EDC, their message is being contradicted by their context. Since learners learn from their total environment, not just in classrooms, changes are required. Granting greater attention to sustainability issues and the empowerment of learners and teachers would allow a better constructive alignment between educational and economic imperatives.     

Multicultural Visions of Globalization: Constructing Educational Perspectives From the East and the West

The thesis of this essay is that globalization is a phenomenon that humankind must be educated for understanding as a process of global evolution. The new world evolving is being defined as requiring a new sense of collective cooperation amongst the peoples of the Earth, if we are to continue to exist on the planet. Educators are in the midst of and have an important role to play in this social and conscious evolution. One of our challenges is to explore the theoretical foundations for framing a new global education agenda. The assertion is that the theories of global, social, and conscious evolution of 20^th century intellectuals and visionaries such as India’s Sri Ghose Aurobindo (1872-1950) and France’s Pierre Teilhard de Chardin (1881-1955) provide the foundation from which to construct a new global educational perspective.     

行星轮上点轨迹的图形特征与虚拟实验

行星轮上点的轨迹存在很多形状与应用价值,基于数学分析与VB编程以及参数化的方法,得到了规则正多边形、规则正多角形、多叶玫瑰线、多圈回归螺旋线、环状相邻缠绕线与无限不循环曲线等几何图形,充分展示了行星轮上点轨迹的图形特征,为设计在一个行程单极限位置或双极限位置作高阶停歇的机构、多个行程单极限位置或双极限位置作高阶停歇的机构提供了理论基础。表明了虚拟实验用于揭示因素完全可控对象的客观规律上的优越性。     

从科教融合到科学引领――中国特色的行星科学建设思路

行星科学是一门新兴交叉学科,形成于20世纪60—70年代的第一次国际深空探测热潮。行星科学是研究太阳系内与系外行星、卫星、彗星等天体和行星系的基本特征,以及它们形成和演化过程的科学。行星科学以深空探测为主要研究手段,由地球科学、空间科学、天文学等学科交叉产生。当今世界美国成为独一无二的行星科学强国,缘于其率先建立了行星科学学科和人才培养体系,以及科学引领深空探测的发展思路。当前国际上处于第二次深空探测热潮的上升期,我国的深空探测事业迅猛发展,取得了举世瞩目的成就,已然成为崛起中的深空探测大国。但是,我国的行星科学学科尚未建立,亦无人才培养体系,无法匹配和支撑国家深空探测战略规划的实施。行星科学学科建设的滞后已成为制约我国成为深空探测强国和行星科学强国的瓶颈。因此,行星科学一级学科建设迫在眉睫。中国科学院大学等高校有条件、有能力、有优势率先建成行星科学一级学科,继而带动相关高校共建中国行星科学人才培养体系,服务和引领未来深空探测计划,推动我国成为行星科学强国。对比美国行星科学发展历程和当今我国国情,我们认为,充分发挥中国科学院大学科教融合办学模式的优势,有望探索出一条有中国特色的行星科学一级学科建设之路。     

Backlash analysis of a new planetary gearing with internal gear ring

Due to low carrying capacity and short life of current ring reducer, we proposed a new planetary gearing with internal gear ring, which consisted of two stages. One was an involute planetary drive and the other was an N-type planetary drive with small teeth difference. The kinematic calculation was conducted based on the analysis of structural composition and working principle. Formulas of backlash calculation for the new planetary gearing were derived by using probabilistic theory and the analytical model was created at the same time. Then, main factors that affect the systematic backlash were introduced and the effects of manufacture error, misaligments and roller bearing parameters on the distribution of backlash were presented. The influence of gear backlash on systematic return difference was performed based on the backlash mathematic model proposed. The results show that the backlash is a little large, of which the backlash of bearing takes a greater part than two gearing stages. So we presented some practical methods to reduce the systematic backlash.     

伯克利加州大学地球与行星科学系本科教育现状研究

本文详细介绍了笔者访问美国伯克利加州大学期间了解和感受到的该校地球与行星科学系本科教育体系及措施。使学生获取知识、培养学生定量分析和解决问题的能力、培养学生的沟通能力是该系本科教育的目的和要求,通过合理的课程设置和有效的主客观评价体系,该系在美国地球科学教育和研究领域长期处于领导地位。     

掘进机履带行走减速器的优化设计

行走减速器是掘进机履带的重要传动部件,传统的设计方法会造成较大的设计余量,使减速箱的体积偏大。为了解决问题采用三级NGW行星齿轮传动,并基于PROE三维软件对其结构特点与实体效果进行优化仿真。     

Finite element analysis of internal gear in high-speed planetary gear units

The stress and the elastic deflection of internal ring gear in high-speed spur planetary gear units are investigated. A rim thickness parameter is defined as the flexibility of internal ring gear. Six evenly spaced linear springs are used to describe the fitting status between internal ring gear and the gearcase, The finite element model of the whole internal ring gear is established by means of Pro/E and ANSYS. The loads on meshing teeth of internal ring gear are applied according to the contact ratio and the load-sharing coefficient. With the finite element analysis （FEA）, the influences of flexibility and fitting status on the stress and elastic deflection of internal ring gear are predicted. The simulation reveals that the principal stress and deflection increase with the decrease of rim thickness of internal ring gear. Moreover, larger spring stiffness helps to reduce the stress and deflection of internal ring gear. Therefore, the flexibility of internal ring gear must be considered during the design of high-speed planetary gear transmissions.