圆弧形波纹膜片的矩阵联乘解法

将圆弧形波纹膜片看作几段圆环壳和中心圆板的组合构件,本文利用钱伟长教授的圆环壳一般解[1]及圆薄板小参数振动理论[2],导出环壳和板的传递矩阵和连接矩阵,用矩阵联乘法求得线性精确解和非线性解,计算结果同W.A.Wildhack的实验[3]是吻合的.     

圆环壳在一般荷载下的轴对称问题

本文推广Новжилов变换,对圆环壳在任意荷载作用下的轴对称问题进行了成功地简化,得到了问题的H.Новжилов型复变量方程.求得了方程的特解,结合钱伟长的齐次方程一般解,给出了环壳一般轴对称问题的一般解答.讨论了常见载荷和闭合环壳情形.     

柔性圆环壳在子午面内整体弯曲的复变量方程及细环壳的一般解

在З.Л.Аксельрад(E.L.Axelrad)非轴对称载荷下柔性旋转壳线性方程的基础上,导出了圆环壳在子午面内整体弯曲的复变量方程和相应的细环壳方程.该方程可与钱伟长给出了一般解的В.В.Новожилов(V.V.Novozhilov)轴对称环壳方程相类比.通过类比,给出了细环壳在子午面内整体弯曲的一般解.所给出的解可以用来计算波纹管整弯曲的应力和端面位移.     

U型波纹管的非线性特性摄动法计算

本文利用圆环壳的一般解[1],引用小参数摄动理论,求得U型波纹管的线性精确解和非线性解.     

中细柔性圆环壳整体弯曲的一般解及在波纹管计算中的应用(Ⅰ)——基本方程和一般解

讨论了圆环壳在横向载荷作用下的整体弯曲问题,提出了中细柔性圆环壳的概念、基本方程和一般解。本文称粗细比(子午线曲率半径与子午线曲率中心到回转轴的距离之比)小于1/3的圆环壳为中细圆环壳;方程的推导基于E.L.Axelrad的柔性壳理论;所得的解含有处理边界问题所必须的积分常数并且在全域内处处收敛;本解能方便地用于有关波纹管的计算。全文共分4个部分:(Ⅰ)基本方程和一般解;(Ⅱ)Ω型波纹管的计算;(Ⅲ)C型波纹管的计算;(Ⅳ)U型波纹管的计算。     

一般旋转壳在轴对称变形下的复变量方程

本文在Love-Kirchhoff的假定下,求得了一般旋转壳在轴对称变形下的复变量方程.当旋转壳是圆截面环壳时,这些方程简化为F.T?lke(1938)[3],R.A.Clark(1950)和B.B.Новожилов(1951)[3]的方程.当平均半径R比环截面半径a大得很多时,求得了细环壳的复变量方程,当这个细环壳的截面是圆形时,简化作为作者(1979)[6]的圆截面的细环壳复变量方程,我们列出了椭圆截面的细环壳复变量方程.当椭圆截面近似于圆截面时,该方程在形式上和圆细环壳方程基本相同.     

中细柔性圆环壳整体弯曲的一般解及在波纹管计算中的应用（I）—基本方程和一般解

讨论了圆环壳在横向载荷作用下的整体弯曲问题，提出了中细柔性圆环壳的概念、基本方程和一般解。本文称粗细比（子午线曲率半径与子午线曲率中心到回转轴的距离之比）小于1／3的圆环壳为中细圆环壳；方程的推导基于E.L.Axelrad的柔性壳理论；所得的解含有处理边界问题所必须的积分常数并且在全域内处处收敛；本解能方便地用于有关波纹管的计算。全文共分4个部分：（I）基本方程和一般妥；（Ⅱ）Ω型波纹管的计算；（Ⅲ）C型波纹管的计算；（Ⅳ）U型波纹管的计算。     

圆环壳在离心力作用下的应力和位移

本文应用文[1]、[2]一般轴对称问题的结果计算了圆环壳在离心力作用下的应力和位移,解答以Fourier级数形式给出,文中分别给出了部分环壳和闭合环壳的算例。     

变壁厚轴对称圆环壳的复变量方程及其一般解

本文导出了变壁厚轴对称圆环壳的复变量方程,并给出了它的一般解.     

半圆弧波纹管的计算——环壳一般解的应用

本文利用前文所得圆环壳的一般解,计算了半圆弧波纹管在轴向力作用下的变形和应力分布.     

Generalizations of the Taut String Method

The taut string method is classically used in statistical applications to obtain a sparse estimation for a density given by point measurements. Mostly, a discrete formulation is employed that interpretes the data and the output as piecewise constant splines. This paper deals with the continuous formulation of this algorithm. We show that it is able to deal with continuous data as well as with discrete data interpreted as Dirac measures. In fact, any one-dimensional finite signed Radon measure is suited as input for the method. Moreover, we study the usage of tubes of nonconstant diameter. Examples indicate that such tubes can be useful in various applications. An existence and uniqueness theorem is given for the continuous formulation of the taut string algorithm with arbitrary tubes of nonnegative diameter.     

Approximation of Solutions of the Neumann Problem in Disintegrating Domains

This article deals with approximation of solutions of the Neumann problem in domains, where small tubes are cut out. With an increasing number of tubes some kind of a porous layer inside the domain is approximated. Our aim is to find an asymptotic solution for the separated limit domains. We show that this asymptotics is described by a boundary value problem for the two limit domains, where the solutions for each domain are connected by the boundary conditions.     

The push-out region of an immersed manifold

We consider immersions: and construct a subspace of which corresponds to a set of embedded manifolds which are either parallel to f, tubes around f or, in general, partial tubes around f. This space is invariant under the action of the normal holonomy group, We investigate the case where is non-trivial and obtain some results on the number of connected components of . Received 24 March 2000.     

Diamond折纸管状结构轴向冲击性能分析

为了降低薄壁管状结构受轴向冲击时的初始峰值载荷,将diamond刚性折纸模型引入到薄壁管状结构的设计中.利用有限元分析方法,以方形截面为例,分析了diamond折纸管状结构的轴向冲击性能.结果表明:相比于传统方形薄壁管,diamond折纸管状结构具有较低的初始峰值载荷和更加平稳的变形过程.得出了diamond折纸管状结构按折纸预折形式变形的临界条件.分析了diamond折纸管状结构在轴向冲击载荷作用下,底角对初始峰值载荷和平均冲击载荷的影响.     

The volume of tubes in complex space forms

In this paper we give the volume of tubes around complex submanifolds in complex space form in terms of the technique of Jacobi fields. This work is supported partially by NNSF of China.     

Effect of fiber orientation and cross section of composite tubes on their energy absorption ability in axial dynamic loading

The crushing behavior of composite tubes in axial impact loading is investigated. Tubes of circular and rectangular cross section are simulated using an LS-DYNA software. The effect of fiber orientation on the energy absorbed in laminated composite tubes is also studied. The results obtained show that rectangular tubes absorb less energy than circular ones, and their maximum crushing load is also lower. The composite tubes with a [+θ/ -θ] lay-up configuration absorb a minimum amount of energy at θ = 15°. The simulation results for a rectangular composite tube with a [+30/–30] lay-up configuration are compared with available experimental data. Cylindrical composite tubes fabricated from woven glass/polyester composites with different lay-ups were also tested using a drop-weight impact tester, and very good agreement between experimental and numerical results is achieved.     

人体体循环输入阻抗的T-Y型管模型*

本文提出了模拟人体体循环输入阻抗的T－Y型管模型,它是O'Rourke[1]提出的,柳兆荣等[2]发展的非对称T型管模型的改进和推广.我们在非对称T型管基础上加添了代表人体两条腿的倒Y字型分叉管,从而形成了T－Y型模型,同时将模型中所有分支管都处理成具有纵向约束的粘弹性管,上肢终端小动脉床采用弹性腔模型,下肢终端小动脉床则采用传统的纯阻力形式.选取了适当参数值后,计算了正常生理情形下和高血压病理情形下的人体体循环的输入阻抗.结果显示理论模拟值和实测结果无论是生理情形或是病理情形都有良好的符合程度.T－Y型管模型比非对称T型管模型更接近人体体循环的生理结构.同时又比过份复杂的多重分叉管模型简单明了得多,因此在考察各种参数对升主动脉输入阴抗的影响.研究心室和血管的耦合机制中将是一个有实用价值的模型.     

Torsion pairs in cluster tubes

We give a complete classification of torsion pairs in the cluster categories associated to tubes of finite rank. The classification is in terms of combinatorial objects called Ptolemy diagrams which already appeared in our earlier work on torsion pairs in cluster categories of Dynkin type A. As a consequence of our classification we establish closed formulae enumerating the torsion pairs in cluster tubes, and find that the torsion pairs in cluster tubes exhibit a cyclic sieving phenomenon.     

Diffusion and convection in a family of tubes

Global existence theorems are given for the solutions of the renal flow equations for a system of parallel tubes. In the system, a solute moves in a fluid through the tubes by diffusion and convection and the tubes exchange fluid and solute with each other through the tube walls. The proofs use a fixed point argument. It is shown that the hypotheses of the theorems include the passive and convective flux formulas used in renal models.     

Partial Decomposition of a Domain Containing Thin Tubes for Solving the Heat Equation

An initial–boundary value problem for the heat equation in a three-dimensional domain containing thin cylindrical tubes is considered. The Neumann condition is set on the lateral boundaries of the tubes. The original three-dimensional problem is reduced to a hybrid-dimensional one in which the heat equation in the tubes is replaced by the one-dimensional heat equation in shorter cylinders (subtubes), and the three- and one-dimensional equations are matched on the bases of the subtubes. The difference between the solutions of the original and hybrid-dimensional problems is estimated using two geometric characteristics: the distance between the bases of the tubes and subtubes and the reciprocals of the minimal positive eigenvalues of the Neumann problem for the Laplace operator in the tube cross sections.