中日国际流变学学术会议(CJICR’91)

<正> 中日国际流变学学术会议(China-Japan International C onf erence on Rheology)由中国力学学会和中国化学会下属流变学专业委员会同日本流变学会联合发起,在北京清华大学举行.会议由中国湘潭大学袁龙蔚和日本京都大学小谷寿共同主持.

理想塑性材料扩展裂纹顶端塑性区内应力场

扩展裂纹顶端弹塑性应力应变场分析是近年来断裂力学发展的重要课题。本文对弹性不可压缩的理想塑性材料中定常扩展裂纹顶端塑性区内的应力应变场进行了系统的数学分析,讨论了速度场和应力场的高阶渐近方程和解的形式,证实高阶渐近场依赖于塑性区和卸载弹性区交界线Γ_B的曲线方程。一旦Γ_3的曲线方程确定下来,高阶渐近场的解答就能确定下来。

磁流体管道中的高超声速流动特性

本文在磁雷诺数Rm=(VL/V_m)(?)1和磁作用参数N(?)1的情况下,讨论了连续磁场对可压导电介质在管道电极与绝缘体连接端面区高超声速流动的影响问题。用复变函数理论求解拉普拉斯方程,得出电流密度和洛伦茨力的解析式,并从计算中,找到了产生环电流的足够条件。导出高超声速流的扰动方程,得出扰动参量的积分公式,并对扰动方程进行数值解,揭示出与不可压介质相似的流动特性,并讨论了在各特殊点附近的流动特性。

太阳耀斑可能的储能过程

本文讨论了太阳活动区和黑子区的无力场的演化。文章分析了无力因子随时间变化的运动学含义,讨论了太阳耀斑具体的储能过程,给出了静力学无力场讨论太阳耀斑储能过程的局限性。最后,又提出了一种子午流场的储能过程。将这些“磁能的储存过程”与“适当的不稳定性导致的爆发过程”相结合起来讨论,就有可能来研究太北北阳耀斑的许多特征。

A mulher na reforma política

Seminário realizado no dia 15 de maio de 2007, pela Comissão de Legislação Participativa da Câmara dos Deputados.

Water and salt movements in simultaneous flood-irrigation and well-drainage operations

This paper describes a new technology for solonchak soil reclamation in which surface flood irrigation of fresh water and pumped wells drainage of salty groundwater are combined. The comprehensive investigation of water and salt movement has been conducted through field test, laboratory simulation and numerical calculation. The dependence of desalination on irrigation water quantity, drainage quantity, leaching time and other parameters is obtained based on the field tests. The entire desalination process under the flood-irrigation and well-drainage operations was experimentally simulated in a vertical soil column. The water and salt movement has been numerically analysed for both the field and laboratory conditions. The present work indicates that this new technology can greatly improve the effects of desalination.

Study of the shock motion in a hypersonic shock system turbulent boundary-layer interaction

Wall pressure fluctuations and surface heat transfer signals have been measured in the hypersonic turbulent boundary layer over a number of compression-corner models. The distributions of the separation shock oscillation frequencies and periods have been calculated using a conditional sampling algorithm. In all cases the oscillation frequency distributions are of broad band, but the most probable frequencies are low. The VITA method is used for deducing large scale disturbances at the wall in the incoming boundary layer and the separated flow region. The results at present showed the existence of coherent structures in the two regions. The zero-cross frequencies of the large scale structures in the two regions are of the same order as that of the separation shock oscillation. The average amplitude of the large scale structures in the separated region is much higher than that in the incoming boundary layer. The length scale of the separation shock motion region is found to increase with the disturbance strength. The results show that the shock oscillation is of inherent nature in the shock wave/turbulent boundary layer interaction with separation. The shock oscillation is considered to be the consequence of the coherent structures in the separated region.

An asymptotic analysis for one dimensional stress wave propagation in damaged viscoelastic media

A regular perturbation technique is suggested to deal with the problem of one dimensional stress wave propagation in viscoelastic media with damage. Based upon the first order asymptotic solution obtained, the characteristics of wave attenuation are studied. In fact, there exist three different time-dependent phenomena featuring the dynamic response of the materials, the first expressing the characteristics of wave propagation, the second indicating the innate effect of visco-elastic matrix and the third coming from the time dependent damage. The comparision of first order asymptotic solution with the numerical results calculated by a finite difference procedure shows that the perturbation expansion technique may offer a useful approach to the problem concerned.

Implantación y desarrollo de los estudios de Economía de la Empresa en la universidad española

[ES] La Economía de la Empresa es una parcela o rama del saber de la Ciencia Económica, cuya finalidad es la de estudiar y dar respuesta a los problemas concretos que se plantean en el seno de la empresa. Su configuración como disciplina autónoma o sustantiva, si bien experimentó un considerable avance durante la segunda mitad del siglo XIX, no se produce en realidad hasta bien avanzado el siglo XX. Este trabajo pretende, en memoria y homenaje al Profesor Emilio Soldevilla, esbozar la presencia y evolución de la Economía de la Empresa en los planes de estudio de las universidades españolas.

Una valoración del sector vinícola riojano

Este trabajo es resultado de la investigación realizada en el marco de la Tesis Doctoral sobre Impacto socioeconómico del sector del vino en Rioja, que elabora M. Larreina.