斜齿三星轮装载机构的谐响应分析

为了研究斜齿三星轮装载机构的动力学行为,利用更新的拉格朗日法建立了钭齿三星轮的力学模型、用Ansys软件创建了星轮机构的模型,由谐响应分析给出了不同激振频率下的星轮等效应力云图以及星轮机构位移响应随频率变化的曲线,由此得到了星轮机构的最大应力,确定了发生应力集中的位置和星轮稳定运行的转速,为研究斜齿三星轮的动力学性质以及改进该型星轮装载机构的设计奠定了基础.     

推移质运动过程的非线性动力学特性

天然沙质海岸及河床上存在着不同形式的床面形态, 其运动变化受床面附近推移质泥沙的运动特性所决定. 从床面层内推移质集体运动出发, 探讨了推移质运动过程的非线性动力学特性, 发现泥沙起动、推移质平衡输沙以及床面形态由平整到沙纹及沙垄等不同发展阶段, 受推移质运动过程的非线性动力特征所决定, 它们分别对应于推移运动过程中的不同非线性状态. 通过与法国夏都水利实验室床面形态试验比较, 进一步证明: “床面形态从平整到沙垄的演化与否”由推移质泥沙运动过程的突变特性所决定, “突变分界线”是平整床面与沙纹及沙垄床面的分界曲线.     

基于LS-DYNA的直齿轮动力学与关键技术研究

本文研究了LS-DYNA有限元分析软件对直齿轮进行动力学接触仿真分析中的关键技术;计算了齿轮副在啮合过程中齿面接触应力、应变的变化及分布情况;找出了齿轮接触最薄弱的部位并提出了修改建议。这对提高轮齿的接触强度和齿轮传递运动的平稳性具有重要意义。     

航天器升空过程振动环境的地面试验条件

卫星、飞船等航天器振动试验目的是考核它们对升空过程低频振动环境的适应性.本文对卫星随火升空和整星地面振动试验两种状态进行了仿真计算,星界面横向振动同的条下,比较两种状态卫星顶点的动响应,结果毫无共同点.这是由于升空过程星界面有角运动,而地面试验却制界面角运动.仿升空状态的计算中,确定了与星界面运动关的角运动,并以此作为振动试验补充条,进行地面振动试验仿真计算,此时卫星顶点动响应与升空状态一致.可见补充角运动条是现航天器地面振动试验与其升空过程振动环境一致的有效方法,也为多自由度振动台的应用和条制定提供了依据.     

基于H-J-C本构模型的掘进机截齿破岩过程的数值模拟

针对掘进机实际外负载难以获取及其载荷特性难以正确把握的现状,提出了利用接触动力学、岩石力学和有限元法等理论和方法构建在显示动力学分析程序LS-DYNA环境下基于H-J-C本构模型的截齿与岩石的接触动力学模型数值模拟平台;利用该平台对掘进机镐形截齿的横摆破岩过程进行了数值模拟,得到了截齿受到的三向阻力曲线;通过载荷特性分析,验证了所得载荷曲线的准确性,并获得了某工况下截齿载荷的主要频率结构;分析了截齿的碎岩机理,发现岩石的破碎是与截齿直接接触的岩石的拉压应力和其周边的剪切应力集中综合作用的结果.     

具有自适应能力的轮-履复合变形移动机器人的移动机构与地面约束关系分析

针对非结构环境中路面软硬相间、平坦与崎岖并存的地形特征,提出并研制出一种对非结构环境具有自适应能力的轮-履复合变形移动机器人（NEZA-I）.NEZA-I由控制系统单元、尾轮单元和两个相同的可变形轮-履复合（Transformable wheel-track,TWT）移动模块组成.每个TWT模块能够在一个驱动力的作用下以轮式和履带式两种运动模式在复杂路面上运动,也能根据地面约束力而改变运动模式（即＂轮式-履带式互换＂）和调整运动姿态（即＂改变履带几何形状＂）.本文旨在介绍NEZA-I机器人的基本结构、驱动系统原理、运动模式及姿态,分析TWT模块内部构件之间运动关系,建立NEZA-I在一些典型的运动情形下移动机构与地面之间的约束关系的数学模型,探究TWT模块内部机构参数对机器人环境自适应性能的影响,优化机构参数.实验表明：NEZA-I移动机构平台具有较强的环境自适应性和越障性能,机构参数的优化结果是合理的,所建立的相关数学模型及参数的分析方法是正确的.同时也验证了NEZA-I自适应移动机构平台概念的可行性,从机构学的角度为机器人环境自适应性的研究提供一个思路.     

俯控式单滑块变质心飞行器控制问题

针对以质点方式的滑块布局无法在实际工程中实现的问题,提出了一种大质量比的单滑块布局模式,并与喷气推力组合实现了飞行器的倾斜转弯.采用大质量比滑块的布局方式不仅易于工程实现而且可以提高飞行器的机动能力.通过动力学分析,结果表明大质量比的滑块在运动过程中会导致飞行器姿态与滑块转角之间的运动耦合,而且在动量交换过程所产生的惯性力矩也会影响飞行器的动态特性,因此滑块不能再作为质点来处理.针对这种强耦合非线性动力学系统,将非线性耦合项和未建模扰动视为总扰动,设计了一种线性扰动观测器对其进行估计,然后利用反馈线性化控制进行补偿.仿真结果验证了这种大质量比滑块布局模式的可行性,所设计的控制器可以实现对姿态指令的跟踪.     

掘进机截割部刚柔耦合动力学建模与仿真研究

将大位移运动与小变形刚-柔耦合体动力学的建模理论应用于掘进机截割部的动态特性研究，利用ANSYS把截割部的截割主轴和截割套筒生成模态中性文件，导入ADAMS中建立刚柔耦合虚拟样机并进行运动学和动力学仿真，研究柔性体对截割部的影响。通过与刚性体模型仿真结果对比，揭示了工作装置中柔性体与刚性体耦合时的运动学、动力学特性。仿真结果表明柔性耦合模型更加符合实际情况。     

非恒定流作用下的推移质泥沙输移实验研究

非恒定流条件下的推移质运动研究无论是在泥沙运动理论还是在实际工程应用中,都具有重要的意义.基于波流水槽实验,对不同速度偏度的非恒定流作用下的推移质运动开展研究.主要通过泥沙粒径、速度偏度等因素对输沙率影响分析,探讨了非恒定流作用下的均匀沙与非均匀沙的运动情况,阐述了恒定流与非恒定流对输沙率影响的差异性,建立非均匀沙输移粗细质量比公式.在此基础上开展理论推导,从受力机理上对实验过程进行了分析.实验结果和理论分析表明,相对于恒定流,非恒定流作用下的泥沙颗粒更易起动和输移.     

四轮转向车辆分数阶控制方法研究

四轮转向系统(4WS)可根据前轮转向和车辆的状态通过后轮的转向提高车辆转弯能力, 同样, 利用这一转向系统可以改进车辆的横向稳定性和操纵性能. 当前轮转向相同时四轮转向车辆的转弯半径大于两轮转向, 而且普通的控制方法不考虑前轮转向的动态过程影响. 本文利用分数阶导数理论提出一种新的四轮转向控制方法, 其不仅考虑前轮转角和横摆角速度的大小, 而且也考虑到转向角速度的影响. 同时也给出控制方法的一些设计方法, 数值计算结果验证了该控制方法的有效性. 通过对两轮转向和四轮转向的转弯车辆的侧偏角、车辆绕质心的横摆角速度和转弯半径等动力学和运动学特性的计算结果比较, 本文的控制方法对四轮转向车辆在转向过程中的瞬态响应有所改进, 并减小了转弯半径.     

Hertz's Mechanics and a unitary notion of force

Heinrich Hertz dedicated the last four years of his life to a systematic reformulation of mechanics. One of the main issues that troubled Hertz in the customary formulation of mechanics was a ‘logical obscurity’ in the notion of force. However, it is unclear what this logical obscurity was, hence it is unclear how Hertz took himself to have avoided it.In this paper, I argue that a subtle ambiguity in Newton's original laws of motion lay at the basis of Hertz's concerns; an ambiguity which led to the development of two slightly different notions of force. I then show how Hertz avoided this ambiguity by deriving a unitary notion of force, thus dispelling the obscurity that lurked in the customary representation of mechanics.     

Kant and the nature of matter: Mechanics,chemistry, and the life sciences

Kant believed that the ultimate processes that regulate the behavior of material bodies can be characterized exclusively in terms of mechanics. In 1790, turning his attention to the life sciences, he raised a potential problem for his mechanically-based account, namely that many of the operations described in the life sciences seemed to operate teleologically. He argued that the life sciences do indeed require us to think in teleological terms, but that this is a fact about us, not about the processes themselves. Nevertheless, even were we to concede his account of the life sciences, this would not secure the credentials of mechanics as a general theory of matter. Hardly any material properties studied in the second half of the eighteenth century were, or could have been, conceived in mechanical terms. Kant's concern with teleology is tangential to the problems facing a general matter theory grounded in mechanics, for the most pressing issues have nothing to do with teleology. They derive rather from a lack of any connection between mechanical forces and material properties. This is evident in chemistry, which Kant dismisses as being unscientific on the grounds that it cannot be formulated in mechanical terms.     

非线性量子力学的建立

笔者在长期研究工作的基础上,从提出非线性量子力学的基本原理出发,建立起了非线性量子力学理论,形成了完整的非线性量子力学的理论体系。从而把量子力学从线性领域推广和发展到非线性领域。在本文中笔者描述了建立这个非线性量子力学的物理背景,它的基本构思,研究的技术路线,产生的实际效果,与国际同类研究比较,本研究的创新和特点以及研究的重大意义。     

Quantum Mechanics as a Principle Theory

I show how quantum mechanics, like the theory of relativity, can be understood as a ‘principle theory’ in Einstein's sense, and I use this notion to explore the approach to the problem of interpretation developed in my book Interpreting the Quantum World.     

The wedge and the vis viva controversy: how concepts of force influenced the practice of early eighteenth-century mechanics

This article discusses the quest for the mechanical advantage of the wedge in the eighteenth century. As a case study, the wedge enlightens our understanding of eighteenth-century mechanics in general and the controversy over “force” or vis viva in particular. In this article, I show that the two different approaches to mechanics, the one that favoured force in terms of velocities and the one that primarily used displacements—known as the ‘Newtonian’ and ‘Leibnizian’ methods, respectively—were not at all on par in their ability to solve the problem of the wedge. In general, only those who used the Leibnizian concept of force or some related notion were able to get to the conventional results. This article thus rebuts the received view that the vis viva controversy was merely a semantic one. Instead, it shows that different understandings of “force” led to real and pragmatic differences in eighteenth-century mechanics.     

在非线性系统中的微观粒子的特性和非线性量子力学理论(下)

在非线性系统中由于存在着与粒子状态相关的非线性相互作用，微观粒子的状态和特征相对于线性系统而发生了很大变化。原有的线性型的量子力学理论不能很好地描述这些微观粒子的状态和特征。至此，必然要发展新的理论。本文研究了微观粒子在非线性作用下的运动特性和本性的变化，说明了在线性作用和非线性场中微观粒子的性质是明显不同的，启示我们必须建立微观粒子在非线性场中运动的新理论。接着我们研究了与微观量子效应迥然不同的宏观量子效应与非线性作用的孤立子运动的紧密关系，结合现代孤立子理论和超导与超流理论，我们首先提出了非线性量子力学的基本原理及在此基础上建立了系统、完整的非线性量子力学理论体系，并得到的一些新结论。最后我们还论证了这个理论的正确性和自洽性，它的运用范围以及它的重大意义。     

一种高速铁路无砟轨道混凝土结构疲劳损伤模型

基于连续损伤力学理论和边界面概念,建立了高速铁路无砟轨道混凝土结构在循环荷载作用下的疲劳损伤模型.模型在主坐标系中采用了拉压两个边界面,根据加载面与极限断裂面、边界面之间的位置关系来计算高速铁路无砟轨道混凝土结构在复杂应力状态下的损伤,并由累积损伤与应变能释放率之间的关系确定循环加载中极限断裂面的变化规律.通过将该理论模型嵌入有限元软件ABAQUS的用户材料子程序UMAT,与同类模型进行比较验证了模型的可行性.最后对高速铁路双块式无砟轨道支承层进行了循环动荷载作用下的疲劳累积损伤分析.结果表明该模型不仅能够较好地反映支承层在循环荷载作用下疲劳损伤非线性演变规律,还可以展现其疲劳损伤分布形态的全过程,为研究高速铁路无砟轨道混凝土结构的疲劳损伤与寿命预测,提供了可行的理论分析方法.     

在非线性系统中的微观粒子的特性和非线性量子力学理论(上)

在非线性系统中由于存在着与粒子状态相关的非线性相互作用，微观粒子的状态和特征相对于线性系统而发生了很大变化。原有的线性型的量子力学理论不能很好地描述这些微观粒子的状态和特征。至此，必然要发展新的理论。本文研究了微观粒子在非线性作用下的运动特性和本性的变化，说明了在线性作用和非线性场中微观粒子的性质是明显不同的，启示我们必须建立微观粒子在非线性场中运动的新理论。接着我们研究了与微观量子效应迥然不同的宏观量子效应与非线性作用的孤立子运动的紧密关系，结合现代孤立子理论和超导与超流理论，我们首先提出了非线性量子力学的基本原理及在此基础上建立了系统、完整的非线性量子力学理论体系，并得到的一些新结论。最后我们还论证了这个理论的正确性和自洽性，它的运用范围以及它的重大意义。     

Mechanics without mechanisms

At the time of Heinrich Hertz's premature death in 1894, he was regarded as one of the leading scientists of his generation. However, the posthumous publication of his treatise in the foundations of physics, Principles of Mechanics, presents a curious historical situation. Although Hertz's book was widely praised and admired, it was also met with a general sense of dissatisfaction. Almost all of Hertz's contemporaries criticized Principles for the lack of any plausible way to construct a mechanism from the “hidden masses” that are particularly characteristic of Hertz's framework. This issue seemed especially glaring given the expectation that Hertz's work might lead to a model of the underlying workings of the ether.In this paper I seek an explanation for why Hertz seemed so unperturbed by the difficulties of constructing such a mechanism. In arriving at this explanation, I explore how the development of Hertz's image-theory of representation framed the project of Principles. The image-theory brings with it an austere view of the “essential content” of mechanics, only requiring a kind of structural isomorphism between symbolic representations and target phenomena. I argue that bringing this into view makes clear why Hertz felt no need to work out the kinds of mechanisms that many of his readers looked for. Furthermore, I argue that a crucial role of Hertz's hypothesis of hidden masses has been widely overlooked. Far from acting as a proposal for the underlying structure of the ether, I show that Hertz's hypothesis ruled out knowledge of such underlying structure.     

Richard Watson

The development of the circular dividing engine in England is traced from Henry Hindley and Jesse Ramsden through the improvements introduced by Ramsden's successors to the self-acting engine of William Simms. Particular emphasis is given to the invention, evolution and transmission of the methods used to achieve accuracy in: dividing the wheel; ratching the teeth and matching them to the endless screw; and mounting the cutter. The procedures adopted by Ramsden and Troughton for correcting initial dividing marks are also described.