Simulating the Effects of Substrate Pre-Heating on the Final Structure of Steel Parts Built by Laser Powder Deposition

Tool steel parts built by laser powder deposition often present a heterogeneous distribution of properties caused by the complex structural transformations that occur during the deposition process. A model describing these transformations has been developed. It couples finite element heat transfer calculations with transformation kinetic theory to predict the final microstructure and properties of the material and their variation across a laser powder deposited part. Pre-heating is often used to reduce the residual stresses and the risk of thermal distortion and cracking. However, this changes the heat transfer conditions and affects the final microstructure and properties. In this work the proposed model was used to evaluate the effects of substrate preheating on the final hardness distribution. The results show that the final hardness depends considerably on the initial temperature of the substrate.Mechanical Engineerin

Non-Linear Supersymmetric σ\sigma -Models and their Gauging in the Atiyah-Ward Space-Time

We present a supersymmetric non-linear \s-model built up in the $N=1$ superspace of Atiyah-Ward space-time. A manifold of the K\"ahler type comes out that is restricted by a particular decomposition of the K\"ahler potential. The gauging of the \s-model isometries is also accomplished in superspace.Comment: 15 pages, Latex, no figure

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Iris BOROWY, Coming to Terms with World Health. The League of Nations Health Organisation 1921-194

Reseñas

Paolo SORCINELLI, La follia della guerra. Storie del maniconio negli anni quaranta, Franco Angeli ; Gli italiani e il cibo. Appetiti, digiuni e rinunce dalla realtà contadina alla società del benesser

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Bertha GUTIÉRREZ RODILLA, La esforzada reelaboración del saber. Repertorios médicos de interés lexicográfico anteriores a la imprent

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Obra ressenyada: Luis Enrique OTERO CARVAJAL, José María LÓPEZ SÁNCHEZ, La lucha por la modernidad. Las ciencias naturales y la Junta para Ampliación de Estudios. Madrid : CSIC, Publicaciones de la Residencia de Estudiantes, 2012

Juan Negrín (1892-1956 ) y la investigación experimental en el Laboratorio de Fisiología de la Junta para Ampliación de Estudios

En el marco del despliegue institucional que vivió la ciencia española durante las tres primeras décadas de nuestro siglo debido a la labor desempeñada por la J.A.E., la investigación experimental en biomedicina ocupó una posición muy preferente, merced a la creación de nuevos laboratorios de Histología normal y patológica, Anatomía microscópica o Serologia y Bacteriología que, junto al Instituto Cajal, elevaron su nivel científico y su prestigio internacional. El Laboratorio de Fisiología General, creado en 1916 y dirigido desde sus comienzos por Juan Negrín López fue el principal impulsor de las investigaciones en fisiología experimental a través de amplias relaciones con instituciones de Europa y América. Negrín fue el catalizador de un amplio grupo de científicos que se formaron en las mejores universidades del mundo. El presente artículo analiza las actividades del Laboratorio de Fisiología General, así como la formación científica y la obra de Juan Negrín

BRS Cohomology of Zero Curvature Systems II. The Noncomplete Ladder Case

The Yang-Mills type theories and their BRS cohomology are analysed within the zero curvature formalism.Comment: 14 pages, latex, no figures, latex improve

Noise suppression by noise

We have analyzed the interplay between an externally added noise and the intrinsic noise of systems that relax fast towards a stationary state, and found that increasing the intensity of the external noise can reduce the total noise of the system. We have established a general criterion for the appearance of this phenomenon and discussed two examples in detail.Comment: 4 pages, 4 figure