Motion of a tiny tool thrown by an astronaut inside a spinning space vehicle in a state of free fall

One of two astronauts, while conducting an experiment inside a spinning space vehicle in a state of free fall neglecting all gravitational effects, throws a tiny tool at the other with a velocity perpendicular to its axis of rotation. Considering the motion of the tool with respect to the rotating frame rigidly fixed to the vehicle, we can obtain the position of the tool at a subsequent time by use of rotational kinematics and geometry without involving the concepts of coriolis and centripetal forces.     

太空站如何造福地球人

Science, medicine, and education will get aboost,says a former astronaut. A board the International Space Station,astro—nauts,cosmonauts,and scientists from around the globeare collaborating1 on science that once was thought only to befiction2.With new scientific tools at their fingertips,space sta-tion crews are working in many areas,including materials sci-ence,medicine,and Earth observation.     

旋转参考系的选取及其应用

阐述了在量子光学中,选取旋转参考系变换系统哈密顿量的一般方法,同时也举例说明了选取适当的旋转参考系,将系统的哈密顿量化成简单的形式,从而可以简化计算并能顺利地解决问题。最后,给出了选取旋转参考系的一般结论。     

简谐激励下输流管的稳定性和混沌运动

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盲童空间认知的参考框架和语言表达

采用旋转范式中的摸箭头和动物排列任务,考察盲童空间认知的参考框架和语言表达。结果表明,在空间认知中,盲童倾向使用相对参考框架和固定参考框架,倾向使用相对空间术语,也有小部分人使用绝对空间术语。盲童空间认知的参考框架和语言表达由盲童的特点决定。视觉经验和空间教育对盲童空间认知操作和空间语言表达有一定影响。     

质点运动的描述

指出了绝对静止系，绝对匀速运动系，绝对加速运动系，惯性系，非惯性系并不存在，确定了相对静止系，相对匀速运动系，相对加速运动系的概念，用位于参照系中的线位置矢量，运动方程，运动轨道描述了质点的运动。     

The role of frames of reference in the development of responsiveness to shading information.

The use of frames of reference in interpreting shading information in pictures was studied with children from 3 to 8 years of age. After learning to discriminate tactually between a convexity and a concavity, the subjects were presented a photograph of the convexity and the concavity in which the only information for differential shape was provided by the relationship between the orientation of the shading on the shapes and the frames of reference. By changing the position of the subject's head, rotating the display, and changing the location of the source of illumination, the relevance of egocentric, environmental, and lighting-specified frames of reference was manipulated. Children in this age range were found to be sensitive to shading information for depth, both when that information was specified by only a single frame of reference and when all three frames of reference were relevant. Differences in the responsiveness to individual frames of reference were found: the egocentric (head-retina) frame of reference was most effective, followed by the environmental reference frame, and finally by the frame of reference based on the location of the light source in the space surrounding the photograph. Responsiveness to the environmental and lighting-based frames of reference increased with age, while responsiveness to the egocentric frame of reference was high for all age groups and did not increase with age.     

洛伦兹变换在三裂变核反应角分布研究的应用

选择参考系是描述物体运动规律时的首要问题,同一物体的运动在不同参考系间物理量存在一定的变换关系.本文系统地论述了在相对论条件下两惯性参考系间物理量的变换公式,并将其运用到新的三裂变反应微观机制的研究中,将质心系中碎块的角分布转化成实验室系下的分布,结果表明实验和理论数值一致,得出该裂变模式主要发生在反应面附近,是经历了两次两体裂变的非平衡过程.     

对自来水厂供水方案选择的分析

本文以普明水厂为例,说明将水泵变速运行以适应用水量的变化又保持恒定的扬程,是最优的一种供水方式。它革除了传统的水塔、水箱、气压罐等容器。因此,投资省、供水质量好,节能效果显著。近年来这一新技术已在水泵站、城市小区、高层建筑、工业及消防用水各领域逐步推广,均获得较好的经济效益。 当用多台泵并联供水时,可将台数控制与转速控制结合在一起,因此可靠性更高,节能效果更好。     

VIDEO MOTION CAPTURE IN VBA——VIDEO-BASED ANIMATION

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超大尺寸超精密数控磨床构型分析

为确定用于超大口径（>=1500mm）光学非球面成形加工的超精密数控磨床的构型设计方案,本文开展了2种不同构型龙门机床的空间运动误差建模及比较研究。基于多体系统理论,通过建立2种构型龙门机床的拓扑结构图,推导二者的空间运动误差模型;并基于该模型,采用仿真手段比较了二者用于超大尺寸光学非球面加工过程的砂轮中心点误差变化规律;仿真结果表明,在加工大口径非球面元件时,工作台移动式的机床构型具有相对较小的空间运动误差,但两种构型龙门机床的误差十分接近。在综合考虑二者在大口径非球面元件加工过程中的其他特点后,确定了该超精密磨削机床构型为工作台固定的桥式龙门结构。     

西方美学参照下的虚静理论

在中西美学的参照和互现中,传统"虚静"理论的动态特质得到了彰显。其外部表现形式是物我合一、凝神沉思、看似静止的主体情态,其内部运动结构又体现为一种外静内动的心理能量场。"虚静"的内涵并非通过静态方式得到呈现,它的"虚"力潜藏于外静内动的相对静止空间内。今人对于"虚静"的研究,必须借助于现代心理学、哲学乃至艺术学的理论工具,从而在民族审美心理的观照下,对现代"虚静"理论进行审视和解读。     

VIDEO MOTION CAPTURE IN VBA

Computer vision has very wide application in human motion capture research. This paper proposes a new approach to do motion capture in video. It is composed of image sequence based tracking of human feature points and the reconstruction of the three-dimension(3D) motion skeleton. First, every part of the human body from top to bottom is tracked on the basis of a human model. The image difference and a morph-block similarity algorithm based on subpixels are used. Then camera calibration is done using the line correspondences between the 3D model and the image. Finally the 3D motion skeleton is established by use of the model knowledge. This approach does not aim at a given mode of human motion. Rather, it analyzes large scale motion from frame to frame in complex, variational background, and sets up a 3D motion skeleton in the perspective projection. The experiment results are presented at the end of the paper. Project (69803009) supported by Natural Science Foundation of China (NSFC) and Key Project of National Development Planning Committee.     

对光速不变现象的剖析

根据牛顿空间由于运动而发生的变化，运用伽利略变换，揭示了光速表现不变现象的原因，论证指出：作为建立狭义相对论理论的基础，“光速不变原理”假设是错误的，所以，狭义相对论将无法成立．     

由均匀运动双螺旋涡丝诱导的流场的解析解

NomenclatureV-Relative velocity vectorV′-Absolute velocity vectorω-Relative vorticity vectorω′-Absolute vorticity vectorR-Pipe radiusa-Radius of cylinder for helical vortex filament2πl-Pitch of i mage helical vortex filamentQ-Flowrate in pipe with an arbitrary cross-sectionΓ-Circulation of each helical vortex filamentV0-Constant transferal velocity of vortex filaments along thez-axisΩ-Constant angular velocity of vortex filaments around thez-axis(a,χ1) ,(a,χ2) -Relative helical …     

刚体定点转动的动量矩与角速度方向之间的关系

讨论了刚体定点转动时,动量矩的方向与角速度的方向之间的关系,得出了两者之间夹角的解析表达式.     

心理空间理论与叙事语篇中的指示语分析

美国认知语言学家Gilles Fauconnier提出的心理空间理论是认知语言学中一个十分重要的部分,它旨在解释语言即时或实时的产生与理解的过程。在语篇的加工与处理中,心理空间理论把语篇中出现的各种实体、各种关系和过程理解为一个个相互关联的心理空间,时于语篇中的指称、同指以及故事情节的理解提供了同一、可靠的方法。本文在心理空间理论的指导下,对叙事语篇中的指示现象进行了尝试性的分析,重点分析了人称指示语,指出了其与传统语篇分析的不同之处及其在语篇构建中的作用。     

大型发酵机多层搅拌流固耦合仿真分析

基于有限元法对流固耦合作用下的刀具转速开展搅拌效果及受力变形分析。 在流体动力学分析中,采用示踪剂浓度法、多重参考系法研究转速对搅拌效果的影响。 将静力学和动力学模块进行连接搭建,研究不同转速下的刀具受力变形情况,获得搅拌叶片的安全转速取值范围。 结果表明:在达到临界转速前,所需混合时间对转速的变化敏感,搅拌桨的受力和变形也随转速的增加而增大;从流场、混合时间、应力和应变的角度综合考虑,搅拌转速设置为200 rpm 时综合指标更高。     

矩形线框进入匀强磁场时运动情况分析

掌握矩形线框进入匀强磁场时的运动情况可进一步理解法拉第电磁感应定律。用解微分方程并结合牛顿运动定律得出其运动的位移、速度和加速度与时间的关系为e-kt函数关系,得出线框在匀强磁场中可以做匀速运动、减速运动或加速运动,弄清其运动曲线关系的实质。     

Unidirectional motion of vehicle on sinusoidal path Can it cause illusory forward and backward motion?

The feeling of being in motion, while observing a moving train passing nearby is a common experience. It is an example of relative motion where a stationary observer experiences an illusory motion caused by a vehicle moving in the opposite direction. It is however counter-intuitive to imagine periodic changes in the direction of relative motion, while the vehicle continues to move in one direction only. To an observer, sitting inside the moving vehicle, periodic changes in direction can lead to the illusion of being in oscillatory forward and backward relative motion. This article, using a simple mathematical model describes how the unidirectional motion of vehicle on a sinusoidal path can lead to the illusion of being in periodic forward and backward relative motion. This work has emerged out of a real life experience during a train journey on the hilly curves from Kalka to Shimla.