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1.
林金 《应用数学和力学(英文版)》1990,11(9):835-847
Relations between the experience of space technology and theory of space and time arefound in this paper.A nontraditional approach to the concepts of space and time isintroduced.The approach is based upon the the analysis of the detailed mechanism of radarmeasurement and nonlinear Doppler effects as measured by an astronaut.The Lorentzfactor and four-dimensional interval t~2-x~2/c~2 may be interpreted fromthe point of view of a space technologist.A“geometrical mean”notion for computing timeinterval is introduced parallelly with the usual arithmetic mean formulas,giving resultscomparable with those of special relativity theory.Space time relationships aredemonstrated on the Poincare diagrams. 相似文献
2.
在分析岩体经观和宏观损伤特征及其与岩体非弹性变形之间关系的基础上,运用损伤面来定义生－－损伤准则,建立了在应力空间描述岩体损伤本构关系一种模型,并对该模型在工程中的应用进行了讨论。 相似文献
3.
研究相对论性定轴转动变质量系统的广义Noether定理,首先给出相对论性定轴转动变质量非完整系统的运动方程的Routh形式;其次利用Hamilton作用量在无限小变换下的不变性,研究了相对论性定轴转动变质量非完整系统的广义Noether定理和相对论性定轴转动变质量非完整系统的广义Noether逆定理;结论具有普遍意义,对于经典情形和相对论情形都适用,若moi为常量,结果化为相对论性定轴转动常质量的Noether定理;若θ<Γi,ωi<Γi,结果化为经典定轴转动变质量系统的Noether定理;若moi为常量,且θi<Γi,ωi<Γi,则结果化为经典定轴转动常质量系统的Noether定理. 相似文献
4.
RELATIVISTIC VARIATION PRINCIPLES AND EQUATION OF MOTION FOR VARIABLE MASS CONTROLLABLE MECHANICAL SYSTEM 总被引：2，自引：0，他引：2
罗绍凯 《应用数学和力学(英文版)》1996,17(7):683-692
ＲＥＬＡＴＩＶＩＳＴＩＣＶＡＲＩＡＴＩＯＮＰＲＩＮＣＩＰＬＥＳＡＮＤＥＱＵＡＴＩＯＮＯＦＭＯＴＩＯＮＦＯＲＶＡＲＩＡＢＬＥＭＡＳＳＣＯＮＴＲＯＬＬＡＢＬＥＭＥＣＨＡＮＩＣＡＬＳＹＳＴＥＭ￥(罗绍凯)ＬｕｏＳｈａｏｋａｉ（ＳｈａｎｇｑｉｕＴｅａｃｈｅｒｓ... 相似文献
5.
林汝耀 《应用数学和力学(英文版)》1994,15(3):223-228
ＴＨＥＣＯＮＳＥＲＶＡＴＩＯＮＬＡＷＡＮＤＴＨＥＲＡＤＩＡＴＩＯＮＯＦＧＥＮＥＲＡＬＲＥＬＡＴＩＶＩＴＹＬａｍＹｕ－ｙｉｕ（林汝耀）（ＤｅｐａｒｔｍｅｎｔｏｆＡｐｐｌｉｅｄＭａｔｈｅｍａｔｉｃｓ）ＨｏｎｇＫｏｎｇＰｏｌｙｔｅｃｈｎｉｃ．ＨｏｎｇＫｏｎ... 相似文献
6.
岩体施工过程损伤演化预测的时变力学分析 总被引：1，自引：0，他引：1
由建立的岩体损伤本构模型，依据时变力学理论对岩体进行不同施工路径下的分步开挖计算，并对施工过程中各点损伤演化历程进行计算机仿真模拟，以预测后续开挖的损伤状态及寻求较优施工步序。理论及算例分析均表明：存在损伤演化时，不同施工步序下岩体终应力位移和损伤状态均不同，设计与施工应进行损伤演化的时变力学分析，以保证施工安全。 相似文献
7.
Gurtin变分原理在矩形板动力初值问题中的应用 总被引：3，自引：0，他引：3
结构动力分析是工程设计中的重要组成部分,传统动力分析方法并不能全面反映动力初值特征,而Gurtin变分原理则被认为是目前唯一能全面反映动力初值特征的变分原理.本文基于位移型Gurtin变分原理,对空间和时间同时离散,建立了一种求解板的动力初值问题的时空有限元法,并对两种边界情况板的振动问题进行了编程计算.计算结果表明时空元法精确度很高且稳定收敛. 相似文献
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9.
首先简单扼要地评述了相对论(狭义相对论和广义相对论)的历史背景,指出它是物理学发展的必然结果:一些物理实验结果与牛顿理论的矛盾召唤着新理论的诞生;为解决这些矛盾而对牛顿理论所做的大量修补工作为相对论的发现奠定了基础;放弃旧的时空观、提出新的物理学原理使爱因斯坦最终建立了相对论．主要部分是广泛而扼要地介绍并评述相对论的主要结果及其实验检验以及最新进展,它们包括：同时性定义、光速不变原理与相对性原理、时间变慢、长度收缩、质—速关系、质—能关系、因果律与超光速;等效原理与广义协变原理、爱因斯坦引力场方程、测地线方程、广义相对论的线性化理论、引力红移、引力波、光线偏折与引力透镜、行星的近日点进动、雷达回波的延缓、中子星、引力塌缩与黑洞、大爆炸宇宙模型、引力能量问题、奇性定理、黑洞热力学与霍金辐射、量子引力等． 相似文献
10.
根据岩体结构理论 ,软弱结构面对岩体变形与破坏具有优先控制作用 ,它与围岩在地震波传播性质 (波速与衰减特性 )上的差别 ,可以利用地震层析成像技术 ,对它进行空间定位 ,进而研究岩体的内部结构特征。针对岩体结构研究的特点 ,本文提出将地震波走时成像方法与地震波衰减成像方法 (振幅与脉冲宽度 )集成到一个处理流程中 ,实现了岩体结构的综合成像方法。 相似文献
11.
施惟慧 《应用数学和力学(英文版)》1994,(12)
ＡＳＴＡＢＩＬＩＴＹＳＴＵＤＹＯＦＮＡＶＩＥＲ－ＳＴＯＫＥＳＥＱＵＡＴＩＯＮＳ（Ⅲ）ＳｈｉＷｅｉ－ｈｕｉ（施惟慧）（ｓｈａｎｇｈａｉＵｎｉｖｅｒｓｉｌｙ．Ｓｈａｎｇｈａｉ）（ＲｅｃｅｉｖｅｄＪａｎ．２０．１９９４；ＣｏｍｍｕｎｉｃａｔｅｄｂｙＣｈｉｅ... 相似文献
12.
In this paper, we present the numerical solution of 2‐phase flow problems of engineering significance with a space‐time finite element method that allows for local temporal refinement. Arbitrary temporal refinement is applied to preselected regions of the mesh and is governed by a quantity that is part of the solution process, namely, the interface position in 2‐phase flow. Because of local effects such as surface tension, jumps in material properties, etc, the interface can in general be considered a region that requires high flexibility and high resolution, both in space and in time. The new method, which leads to tetrahedral (for 2D problems) and pentatope (for 3D problems) meshes, offers an efficient yet accurate approach to the underlying 2‐phase flow problems. 相似文献
13.
Ma Jun-hai Associate Professor Doctor Chen Yu-shu Professor Doctor Director 《应用数学和力学(英文版)》2000,21(11):1237-1245
The state space reconstruction is the major important quantitative index for describing non-linear chaotic time series. Based on the work of many scholars, such as: N.H.Packard, F.Takens, M. Casdagli, J.F.Gibson, CHEN Yu-shu et al, the state space was reconstructed using the method of Legendre coordinate. Several different scaling regimes for lag time τ were identified. The influence for state space reconstruction of lag time τ was discussed. The result tells us that is a good practical method for state space reconstruction. 相似文献
14.
ＯＮＴＨＥＳＴＡＢＩＬＩＴＹＯＦＦＯＲＣＥＤＤＩＳＳＩＰＡＴＩＶＥＮＯＮＬＩＮＥＡＲＳＹＳＴＥＭ￥ＣｈｅｎＤａｄｕａｎ（陈达段）ＬｉｕＸｉａｏｍｉｎｇ（刘晓明）ＳｈｉＷｅｉｈｕｉ（施惟慧）（ＳｈａｎｇｈａｉＵｎｉｖｅｒｓｉｔｙ．Ｓｈａｎｇｈａｉ２００... 相似文献
15.
ＡＮＡＬＹＴＩＣＡＬＳＯＬＵＴＩＯＮＳＯＦＴＨＥＨＥＬＩＣＡＬＦＬＯＷＯＦＮＯＮＮＥＷＴＯＮＩＡＮＦＬＵＩＤＩＮＥＣＣＥＮＴＲＩＣＡＮＮＵＬＡＲＳＰＡＣＥＺｈａｎｇＨａｉ－ｑｉａｏ（张海桥）ＷｕＪｉ－ｚｈｏｕ（吴继周）（ＴｈｅＤｅｐａｒｔｍｅｎｔｏｆ... 相似文献
16.
非定常流动变分原理的建立使得用有限元法来求解多工况点的设计问题成为可能.本文在刘高联的非定常变分理论的基础上,对定常变分问题进行时间相关有限元求解.但由于可压缩非定常位势流动的控制方程是双曲型的,简单地把时间当作同空间一样的物理维来求解是不可行的.而现有的时-空有限元法极其复杂,增加了计算复杂度,使其很难用于工程设计中.为此,文[2、3]提出了求解一维非定常问题的新型时-空有限元法.本文把该方法推广到二维流动,用它求解二维弯管内的流动和翼型绕流问题.计算结果与用定常方法求得的结果几乎重合,说明该方法可以用于多维时间相关求解. 相似文献
17.
Z.‐N. Wu 《ZAMM - Journal of Applied Mathematics and Mechanics / Zeitschrift für Angewandte Mathematik und Mechanik》2004,84(9):647-655
The equations governing incompressible and compressible inviscid flows and written in the physical frame (t,x,y,z) are known to be linearly well‐posed and exhibit elliptic or hyperbolic nature. The linear well‐posedness is considered here for these equations under a space‐time transformation (t,x,y,z) → (τ,ξ,η,ς), where the pseudo‐time τ and the new space coordinate (ξ,η,ς) all depend on (t,x,y,z). This type of transformation is typical in Computational Fluid Dynamics when local time‐stepping is used and it could be useful for uniformly treating problems such as mixed fast‐slow unsteady flows in which the flow is fast unsteady somewhere and slowly unsteady or steady elsewhere and mixed incompressible‐compressible flows. It is found that the transformation may alter the ellipticity, the hyperbolicity, and even the well‐posedness of the original equations. 相似文献
18.
廖晓昕 《应用数学和力学(英文版)》1982,3(2):267-279
In this paper, firstly we give the criterion for the absolute stability of the second canonical form for the control system, including the equation of the longitudinal motions of a plane as a particular example. The corresponding result in [8], [9] is a particular example given in this paper. Secondly, we give the criteria for the absolute stability of the first canonical form in the usual case and in the critical case. Finally, we give some criteria for the absolute stability of the general form for the direct control system.All the results in this paper merely depend upon the relations between the parameters of the system itself to give an explicit algebraic discriminant. 相似文献
19.
The accuracy of numerical simulations of free‐surface flows depends strongly on the computation of geometric quantities like normal vectors and curvatures. This geometrical information is additional to the actual degrees of freedom and usually requires a much finer discretization of the computational domain than the flow solution itself. Therefore, the utilization of a numerical method, which uses standard functions to discretize the unknown function in combination with an enhanced geometry representation is a natural step to improve the simulation efficiency. An example of such method is the NURBS‐enhanced finite element method (NEFEM), recently proposed by Sevilla et al. The current paper discusses the extension of the spatial NEFEM to space‐time methods and investigates the application of space‐time NURBS‐enhanced elements to free‐surface flows. Derived is also a kinematic rule for the NURBS motion in time, which is able to preserve mass conservation over time. Numerical examples show the ability of the space‐time NEFEM to account for both pressure discontinuities and surface tension effects and compute smooth free‐surface forms. For these examples, the advantages of the NEFEM compared with the classical FEM are shown. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
20.
An integral equation approach is utilized to investigate the added mass and damping of floating production,storage and offloading system(FPSO system).Finite water depth Green function and higher-order boundary element method are used to solve integral equation.Numerical results about added mass and damping are presented for odd and even mode motions of FPSO.The results show robust convergence in high frequency range and can be used in wave load analysis for FPSO designing and operation. 相似文献