绕圆柱体跨声速流场

本文将保角曲线坐标方法应用于绕物体外部的跨声速流动.文中讨论了圆柱体跨声速绕流,计算了来流马赫数M_∞。为亚临界,超临界和M_∞为l的流场.给出了不同来流马赫数下柱面马赫数和压力分布,柱面前端中心流线上马赫数分布.给出了超临界绕流时不同来流马赫数下的声速线和来流马赫数M_∞从0.2,0.3到1的等马赫数线分布.本文部分结果与已有的理论结果进行了比较.本方法计算简单,精度好,是计算厚体跨声速绕流的有效方法,适用于不同形状的柱体和机翼的跨声速绕流.

Equilibrium of isolated magnetostatic flux structure

Two-dimensional magnetostatic models of flux structure confined in stratified atmosphere are discussed in the present paper. The magnetic field in the flux structure is assumed to be force-free at the first step. Numerical solutions for this nonlinear free boundary problem are obtained by finite element method. Results show clearly the relation between the inside fields and outside pressure, especially the influence of atmospheric pressure distribution on the flux structure.

Crack extension and kinking in laminates and bicrystals

Singular fields at the tip of an interface crack in anisotropic solids are reviewed with emphasis on establishing a framework to quantify fracture resistance under mixed mode conditions. The concepts of mode mixity and surface toughness are unified by using generalized interface traction components. The similarity between the anisotropic theory and existing isotropic theory is shown. Explicit formulae are given for misoriented orthotropic bimaterials with potential applications envisioned including composite laminates and semiconductor crystals. Competition between crack extension along the interface and kinking into the substrate is investigated using a boundary layer formulation. Several case studies reveal the role of anisotropy. An explicit complex variable representation for orthotropic materials and a solution to a dislocation interacting with a crack are presented in two self-contained Appendices.

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.

The dynamic evolution of the kepler supernova remnant

been analyzed in detail. The effects ofm icroscopic energy transfer from

A atuação do Congresso Nacional na celebração de tratados internacionais : legislatura 1999-2002

Discute as posições doutrinárias a respeito do alcance do artigo 49, I da Constituição Federal, quanto à competência do Poder Legislativo para resolver definitivamente sobre tratados internacionais. Realiza estudo de casos sobre projetos de decreto legislativo referentes a acordos internacionais durante a legislatura 1999-2002. Identifica, na apreciação do Acordo Nuclear Brasil/Estados Unidos sobre a Base de Alcântara, aspectos do entendimento da Câmara dos Deputados quanto à possibilidade de fazer ressalvas e emendas a textos de atos internacionais.

Voisinage et hábitat dans les communautés des Pyrénées Occidentales entre le XV et le XVIIIe siècles : de la croissance au blocage

Publicado dentro de la colección «Méridiennes» (ISSN: 1950-0130)

EQUIVALENT MODEL OF EXPANSION OF CEMENT MORTAR UNDER SULPHATE EROSION

The expansion property of cement mortar under the attack of sulfate ions is studied by experimental and theoretical methods. First, cement mortars are fabricated with the ratio of water to cement of 0.4, 0.6, and 0.8. Secondly, the expansion of specimen immerged in sulphate solution is measured at different times. Thirdly, a theoretical model of expansion of cement mortar under sulphate erosion is suggested by virtue of represent volume element method. In this model, the damage evolution due to the interaction between delayed ettringite and cement mortar is taken into account. Finally, the numerical calculation is performed. The numerical and experimental results indicate that the model perfectly describes the expansion of the cement mortar.

Euskarara bikoizten diren ikus-entzunezko telebista-produktuak: ikerketa esparru landu gabea

Raquel Merino Álvarez, José Miguel Santamaría, Eterio Pajares (eds.)