Porosity detection in high pressure die castings - Part 2 - Non-destructive characterization of pores in HPD castings using active thermpography: numerical simulation and experimental validation

Ever larger high pressure die castings (HPDC) with ever thinner walls raise the issue of casting defects. Properties of components are often strongly influenced by inner porosity. In the case of high pressure die castings, shrinkage and gas porosity occur. Two possibilities of characterizing porosity - by microscopy and acitve thermography - are dealt with in two articles. In the previous article, the microscopic investigations are presented. In this article, first the feasibility of thermographic detection will be discussed based on simulations and, thereafter, the experimental determination of porosity with active thermography will be described

Who were ‘the people’? Classes and movements in East Germany, 1989

There is no shortage of literature on the East German revolution of 1989, but class analyses have been few and far between. In this paper, I survey a number of interpretations of the class composition of the 1989 movements—namely, that they comprised ‘the people’ or the intelligentsia—and find them wanting. I also subject Linda Fuller’s thesis on the non-participation of the working class to detailed examination. Against Fuller, I show that workers were involved en masse, and that although the decisive part they played was on the streets, this movement synergised with upheaval in workplaces, too