顾氏不动点解法——数独题通用解法

"数独"意为"每个数字只能出现一次",起源于中国的古代的九宫格.通过运用严格逻辑推理方法,顾氏不动点解法找到两条或两条以上不同的逻辑路径的交点,即数独题目的关键点,找到一种解决"数独"问题的通用方法.     

顾氏不动点解法——数独题通用解法

“数独”意为“每个数字只能出现一次”,起源于中国的古代的九宫格。通过运用严格逻辑推理方法,顾氏不动点解法找到两条或两条以上不同的逻辑路径的交点,即数独题目的关键点,找到一种解决“数独”问题的通用方法。     

General background and approach to multibody dynamics for space applications

Multibody dynamics for space applications is dictated by space environment such as space-varying gravity forces, orbital and attitude perturbations, control forces if any. Several methods and formulations devoted to the modeling of flexible bodies undergoing large overall motions were developed in recent years.Most of these different formulations were aimed to face one of the main problems concerning the analysis of spacecraft dynamics namely the reduction of computer simulation time. By virtue of this, the use of symbolic manipulation, recursive formulation and parallel processing algorithms were proposed. All these approaches fall into two categories, the one based on Newton/Euler methods and the one based on Lagrangian methods; both of them have their advantages and disadvantages although in general, Newtonian approaches lend to a better understanding of the physics of problems and in particular of the magnitude of the reactions and of the corresponding structural stresses. Another important issue which must be addressed carefully in multibody space dynamics is relevant to a correct choice of kinematics variables. In fact, when dealing with flexible multibody system the resulting equations include two different types of state variables, the ones associated with large (rigid) displacements and the ones associated with elastic deformations. These two sets of variables have generally two different time scales if we think of the attitude motion of a satellite whose period of oscillation, due to the gravity gradient effects, is of the same order of magnitude as the orbital period, which is much bigger than the one associated with the structural vibration of the satellite itself. Therefore, the numerical integration of the equations of the system represents a challenging problem.This was the abstract and some of the arguments that Professor Paolo Santini intended to present for the Breakwell Lecture; unfortunately a deadly disease attacked him and shortly took him to death, leaving his work unfinished. In agreement with Astrodynamics Committee it was decided to prepare a paper based on some research activities that Paolo Santini performed during almost 50 years in the aerospace field. His researches spanned many arguments, encompassing flexible space structures, to optimization, stability analysis, thermal analysis, smart structure, etc. just to mention the ones more related to the space field (Paolo Santini was also one the pioneers of the studies of composite wing structures, aeroelasticity and unsteady aerodynamics for aeronautical applications). Following notes have been prepared by Paolo Gasbarri who was one of Paolo Santini collaborators for almost 15 years, they will attempt to offer a sketch of Professor Santini's activity by focusing on three main topics: the stability of flexible spacecrafts, the dynamics of multibody systems and the use of the smart structure technology for the space applications.     

General dynamics of a large class of flexible satellite systems

The paper presents a general formulation for librational dynamics of satellites with an arbitrary number, type and orientation of deploying flexible appendages. In particular, the case of beam-type flexible appendages deploying from a satellite in an arbitrary orbit is considered. The governing nonlinear, nonautonomous and coupled equations for vibration of the appendages and libration of the satellite are integrated numerically. Several cases of practical importance are considered making the system progressively more general and hence complex: (i) planar case representing pitch and appendage oscillations in the orbital plane; (ii) general attitude motion with planar vibrations of flexible members; (iii) above two cases together with the out-of-plane component of vibrations. Results show that under critical combinations of the system parameters the combined effect of flexibility and deployment can be substantial.     

Regularization of the Perturbed Spatial Restricted Three-Body Problem by <Emphasis Type="Italic">L</Emphasis>-Transformations

Equations of motion for the perturbed circular restricted three-body problem have been regularized in canonical variables in a moving coordinate system. Two different L-matrices of the fourth order are used in the regularization. Conditions for generalized symplecticity of the constructed transform have been checked. In the unperturbed case, the regular equations have a polynomial structure. The regular equations have been numerically integrated using the Runge–Kutta–Fehlberg method. The results of numerical experiments are given for the Earth–Moon system parameters taking into account the perturbation of the Sun for different L-matrices.     

Hydrodynamic Analogy for the Solution to the Doubly Averaged Hill Problem Disturbed by Precession of the Orbit Plane of a Disturbing Body

A hydrodynamic analogy for the solution to a satellite version of the restricted three-body problem is considered with allowance made for precession of the disturbing body orbit. Applying, in the first approximation, the analytical solution to a doubly averaged equation system obtained in 1961 by M.L. Lidov, we consider the precession of the disturbing body orbit as some disturbing factor. The appropriate model enables us to describe the general pattern of integral curves in the entire area of their existence as a picture of flow lines of the potential motion of some fictitious homogeneous incompressible fluid. For the synthesis of an adequate mathematical model, a method similar to the Pade approximation is used. The obtained model and its discrete continual analog allow us to present, in a pictorial form, the disturbance of orbits under the effect of precession of the disturbing body orbit.     

《2006年中国的航天》白皮书

国务院新闻办公室于2006年10月12日发布了《2006年中国的航天》白皮书,这是中国政府继2000年11月22日首次发表《中国的航天》白皮书以后,发表的第二版关于中国航天活动的白皮书。这一白皮书的发表,回答了国内和国际上对中国航天事业发展的关切,表明了中国政府对中国航天事业发展的高度关注,重申了中国坚定不移地走和平发展的道路以及和平探索、利用外层空间的愿望,以利于增进国际社会对中国航天事业的了解,进一步加强国际空间方面的合作与交流。     

约束条件下水平冲量多弧段交会机动方案设计

在交会过程的近距离寻的段 ,由于地面观测条件和追踪航天器燃料的限制 ,提出了固定时间交会和最大燃料消耗量的约束问题。本文探讨在此条件下 ,如何实现水平冲量多弧段交会机动。分析了交会过程中每一次机动的决定性因素 ,给出了解算满足两个过程约束条件的迭代算法 ,仿真算例表明了该算法的可行性。     

老子深邃的贵身思想

老子关注人的一项重要内容就是要确定身与物谁贵谁轻。他主张贵身,反对以物役身;人是目的,物为手段;人以身为贵,依道贵身;贵身有道。     

浅议如何发挥带班的重要作用

班组是管制运行的最小组织单位，直接承担着保障飞行安全的重任。带班作为班组的组织者、领导者，担负着管理班组、监控动态、不正常情况处置、协调关系的诸多职能。要把一个班组管理好、组织好、引导好、协调好，让每一名员工心向一处想，劲往一处使，建立一个安全、和谐、具有很强凝聚力的集体，概括地来说，带班应当在‘皇荧率”、“落实”、“补漏”、“卸载”、“抱团”等五个方面发挥重要的作用。     

词汇教学中的问题思考

词汇的记忆与掌握，对以后词汇的灵活和正确使用是非常必要的。对于任何语言的初学者来说，词汇的掌握都是一个繁重的任务。传统的词汇教学往往把重点放在学生的业余时间对词汇的机械记忆上，可是这种方法忽略了在课堂上来自于教师指导的重要性。本文建议每位教师在课堂上应该尝试创造不同的形式，以便学生能够积极主动而不是被动地学习词汇。     

介质体散射分析中奇异积分处理

为消除高阶矩量法（MOM）求解表面积分方程时的奇异积分,提出了一种采用混合域基函数精确计算奇异积分的方法。通过分离奇异积分项,用变量替换求解析解,与高斯积分法获得的非奇异积分值相加,求得阻抗元素。仿真计算表明：该法的结果和文献中低价MOM吻合。     

客车车身骨架模态的有限元分析

车身是客车的关键总成,车身模态是车身结构中首先要考虑的重要指标之一,它不仅影响客车的可靠性和使用寿命,还影响乘坐的舒适性.文章运用解析模态法,通过大型有限元软件I-DEAS建立有限元模型并施加载荷,再经过解算,得到客车车身模态的固有频率和振型,为客车车身结构的分析计算、后续结构改进提供依据.     

有限合伙制度中普通合伙人的信义义务研究

有限合伙制度主要存在于英美法系国家之中,它在中小型企业和风险投资业的发展上发挥了非常重要的作用。我国在2006年修订合伙企业法过程中以专章的形式规定了有限合伙制度。论文就有限合伙制度中普通合伙人的信义义务进行了理论上的详细探讨,希望能有助于我国有限合伙法律制度的发展与完善。     

几种常见赌博的数学问题

对三类抽奖活动本文利用排列组合与数理统计等知识，进行了分析、揭露，以此告诫人们不要上当受骗。     

中国探测双星圆满完成设计寿命期的科学和工程目标

分别于2003年12月30日和2004年7月25日发射升空的探测1号和探测2号两颗卫星，目前已经圆满完成了整个设计寿命期的科学和工程门标探测双星有力地推动了我国空间科学的跨越式发展。双旱至今工作正常，目前按照用户提出的延寿需求，设计寿命分别为18个月和12个月的两颗卫星分别完成了延长一个生命周期的可行性论证工作。这意味着探洲双星的空间寿命将分别至少还有一个设计寿命期。这是8月6日航天东方红卫星有限公司和中科院空间中心在京联合组织召开的探测双星在轨运行总结会上传出的信息。     

几种常见赌博的数学问题

对三类抽奖活动本文利用排列组合与数理统计等知识,进行了分析、揭露,以此告诫人们不要上当受骗.