Energy Dissipation In Fracture Of Bulk Metallic Glasses Via Inherent Competition Between Local Softening And Quasi-Cleavage

Compression, tension and high-velocity plate impact experiments were performed on a typical tough Zr41.2Ti13.8Cu10Ni12.5Be22.5 (Vit 1) bulk metallic glass (BMG) over a wide range of strain rates from similar to 10(-4) to 10(6) s(-1). Surprisingly, fine dimples and periodic corrugations on a nanoscale were also observed on dynamic mode I fracture surfaces of this tough Vit 1. Taking a broad overview of the fracture patterning of specimens, we proposed a criterion to assess whether the fracture of BMGs is essentially brittle or plastic. If the curvature radius of the crack tip is greater than the critical wavelength of meniscus instability [F. Spaepen, Acta Metall. 23 615 (1975); A.S. Argon and M. Salama, Mater. Sci. Eng. 23 219 (1976)], microscale vein patterns and nanoscale dimples appear on crack surfaces. However, in the opposite case, the local quasi-cleavage/separation through local atomic clusters with local softening in the background ahead of the crack tip dominates, producing nanoscale periodic corrugations. At the atomic cluster level, energy dissipation in fracture of BMGs is, therefore, determined by two competing elementary processes, viz. conventional shear transformation zones (STZs) and envisioned tension transformation zones (TTZs) ahead of the crack tip. Finally, the mechanism for the formation of nanoscale periodic corrugation is quantitatively discussed by applying the present energy dissipation mechanism.

Teología pastoral Inter Loci : una disciplina teológica ante el aporte de las experiencias creyentes en escenarios sociales contemporáneos

Resumen: El texto realiza una relectura del método Ver-Juzgar-Actuar teniendo en cuenta el acercamiento biográfico que ofrecen las ciencias sociales. Propone considerar que la Teología Pastoral desarrolla así un discurso sobre la Iglesia, la Academia y la Plaza Pública en el cruce que estos ámbitos tienen en las mismas prácticas cristianas, dando lugar a una Teología Inter Loci. Y describe el perfil teológico emergente en dicha experiencia utilizando el marco de las inteligencias múltiples.

A Supply Function Competition Model for the Spanish Wholesale Electricity Market

We model the Spanish wholesale market as a multiplant linear supply function competition model. According to the theory, the larger generators should have supply curves for each plant which are to the left of the supply curves of plants owned by smaller generators. We test this prediction for fuel plants using data from the Spanish Market Operator (OMEL) from May 2001 to December 2003. Our results indicate that the prediction of the model holds.

A inter-relação dos trabalhos realizados pela Secretaria de Controle Interno da Câmara dos Deputados com os componentes da metodologia utilizada pelo Committee of Sponsoring Organizations (COSO)

Oferece uma visão de como a Secretaria de Controle Interno (Secin) da Câmara dos Deputados tem atuado em conformidade com a sua missão e com o instrumental fornecido pelo Committee of Sponsoring Organizations of the Treadway Commission (Coso).