Analysis and design of mechanical crack arrestors for gas pipeline

Mechanical arrestors are frequently used in gas transmission pipelines to prevent the possibility of long running cracks. These arrestors have the effect of reducing the pipe from opening as the crack passes. This decreases the available crack driving force and, as a result, crack arrest may take place. This essentially is a second line of defence against catastrophic failure in the event crack initiation cannot always be prevented. A novel analyzing method presented in this paper has been developed to investigate the suitability of these crack arrestors. This is based on a fluid/structure/fracture interaction package, PFRAC. A dynamic finite element approach has been developed for a three dimension curved beam with initial plane curvature, which has been implemented in PFRAC to simulate the behaviour of the arrestor. The contact conditions between the pipe wall and the arrestor, along with the various computational procedures, are described. Several numerical results for a cracked pipe with arrestors are presented and compared with those for pipes without arrestors.     

锌在食管癌变中的作用

应用日立１８０－３０型原子吸收火焰分光光度计，对３６例食管癌组织中的微量元素锌进行了测定，并与３０例食管癌患者的癌旁正常食管组织和１２例正常人的食管组织进行了对照比较，结果表明：癌组织锌含量明显低于癌旁组织和正常食管组织锌含量，癌旁组织锌含量又显著低于正常食管组织锌含量，有淋巴结转移和恶性程度高的食管癌组织中锌含量明显减少，提示锌缺乏时可以诱发食管癌，在食物中补充锌等能预防食管癌的发生。     

南昌大学（北区）饮用水中As,Se,Hg,Zn,Fe等无机元素的研究

从南昌大学和水的Ａｓ、Ｈｇ、Ｐｂ、Ｃｄ、Ｓｅ、Ｚｎ等１０种无机元素的测定研究入手，论述了这些无机元素与人体的关系。并将南昌大学的饮用水和南昌市市区饮用水与生活用水水质标准进行对比，证明南昌大学的饮用水并未污染。     

An Analysis and Simulation of Failure in Dower Connectors

Ｐｏｗｅｒｃｏｎｎｅｃｔｏｒ,ａｓｏｎｅｋｉｎｄｏｆｆｉｔｔｉｎｇｓ,ｉｓｕｓｅｄｔｏｃｏｎｎｅｃｔｐｏｗｅｒｅｑｕｉｐｍｅｎｔｔｏｃｏｎｄｕｃｔｏｒ,ｃｏｎ ｄｕｃｔｏｒｔｏｗｉｒｅｏｒｗｉｒｅｔｏｗｉｒｅｉｎｐｏｗｅｒｌｉｎｅｓ.Ｏｗｉｎｇｔｏｉｔｓｓｉｍｐｌｅｓｔｒｕｃｔｕｒｅ ,ｅａｓｙｉｎｓｔａｌｌａｔｉｏｎａｎｄｌｏｗｃｏｓｔ,ｂｏｌｔ ｔｙｐｅ ｐｏｗｅｒｃｏｎｎｅｃｔｏｒ ｐａｒａｌｌｅｌ ｇｒｏｏｖｅｃｌａｍｐｉｓｗｉｄｅｌｙｕｓｅｄｉｎｏｖｅｒｈｅａｄｐｏｗｅｒｔｒａｎｓｍｉｓｓｉｏｎａ…     

导柱有限元分析计算

应用UG软件 ,对某装置中的承力零件 -导柱 ,用有限元法对其进行了应力分析计算 ,通过分析计算较全面掌握了导柱的薄弱受力环节 ,给出了导柱的应力、应变图。     

细胞自动机方法解小挠度薄板弯曲问题

固体力学中的细胞自动机方法是一种分析固体力学问题的新方法，它将结构的静平衡认为是在力和位移边界条件下，物体元胞间的自组织过程，它不需要象现有有限元那样形成整体刚度矩阵和求解整体平衡方程，对计算机容量要求低，可望成为分析大型结构的有效方法，且特别适宜于并行计算。为拓展其应用范围，本文将其应用于小挠度弹性薄板弯曲的静力计算以检验其可行性。文中给出了详细的计算步骤，以实际算例为基础，探讨了该方法的有效性，并对其优点和目前存在的问题进行了讨论。     

光纤电场传感器的有限元分析

介绍了具有压电聚合物护套的光纤电场传感器的有限元分析 ,这种光纤电场传感器能响应 10 0 Hz至 5 0 MHz的频率。采用有限元分析可以预知低频段 (轴向非约束 ) 0 .0 19rad/(V· m )的相位偏移和在高频段 (轴向约束 ) 8.2× 10 - 4rad/(V· m)的相位偏移。当频率高于 7MHz时 ,光学响应主要是光纤和聚合物护套组合材料的径向谐振。模拟预测的谐振尖峰和合成理论推算出的谐振尖峰具有很好的一致性     

On stress rate and plasticity constitutive equations referred to a body-fixed coordinate system

Investigators have viewed the stress rate in two different ways: the material (body-fixed) point of view and the Eulerian point of view. We discuss the Zaremba–Jaumann rate and Oldroyd’s rate from the material viewpoint and apply them to the material formulation of a theory of plasticity for materials undergoing anisotropic plastic deformation. Significant advantages of the material formulation are that the derivation of equations is straight forward, the distortion of yield surface can be easily accounted for, and the issue of self-consistent elastic equation does not arise.     

An immersed finite element space and its approximation capability

This article discusses an immersed finite element (IFE) space introduced for solving a second‐order elliptic boundary value problem with discontinuous coefficients (interface problem). The IFE space is nonconforming and its partition can be independent of the interface. The error estimates for the interpolation of a function in the usual Sobolev space indicate that this IFE space has an approximation capability similar to that of the standard conforming linear finite element space based on body‐fit partitions. Numerical examples of the related finite element method based on this IFE space are provided. © 2004 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 20: 338–367, 2004