An investigation is performed concerning the applicability of inverse procedures, using optimization and simple experiments, for characterization of WC/Co powder materials. The numerical procedure is combined with uniaxial die-compaction experiments using an instrumented die, which allows direct measurement of the distribution of radial stress during the experiments. Finite-element (FE) methods and an advanced constitutive description of powder materials are relied upon to model the compaction experiment. Optimization using a surrogate model is used to determine some of the parameters in the constitutive description. These parameters in the material model are said to be found (with some accuracy) if the output from the FE simulation is similar to the experimental data. It is found that even though a complete constitutive description of the powder materials investigated cannot be achieved using this approach, many important material parameters can be determined with good accuracy.

Parameters in a complex material model for powder compaction, based on a continuum mechanics approach, are evaluated using real insert geometries. The parameter sensitivity with respect to density and stress after compaction, pertinent to a wide range of geometries, is studied in order to investigate completeness and limitations of the material model. Finite element simulations with varied material parameters are used to build surrogate models for the sensitivity study. The conclusion from this analysis is that a simplification of the material model is relevant, especially for simple insert geometries. Parameters linked to anisotropy and the plastic strain evolution angle have a small impact on the final result.

The low alloy steel powder Distaloy { , is today widely used in applications demanding high strength and wear resistance. Its basic properties and composition were designed half a century ago in the USA. The advantage lay in the fact that it was a partial prealloy, i.e. the alloying elements -copper, nickel and molybdenum -were bonded in particulate form to the basic iron particles, thus avoiding impairment of the compressibility. By balancing the contents of nickel and copper it was possible to minimize dimensional change on sintering. Bonding the alloy particles to the iron particles minimised segregation and also contributed to dimensional stability. Carbon was added conventionally as fine graphite. However, the new powder, marketed as Ancoloy, did not take off in North America, due to the lack of suitable applications, the cost of the alloying elements and -above all -the poor compressibility and high oxygen content of the iron powder then available. The high, variable oxygen content made it impossible to control the carbon content with the precision necessary to achieve the desired strength and hardness. In the 1960s, demand for high strength precision parts emerged in the European car industry, initially at Citroen, which pioneered increased use of PM parts in European cars. The component was (and still is) the synchronising hub used in manual transmissions. Ho ¨gana ¨s had in the mid-1960s developed a sponge iron powder with much higher compressibility, and this was taken as a raw material for an improved grade, later to be called Distaloy SA. This new powder had improved compressibility and very low oxygen and carbon contents, which made it possible to make the high strength precision parts that the car industry required. Distaloy was immediately accepted and used, first in the French car industry, then elsewhere in Europe and subsequently also in Japan. Some years later, when high compressibility atomised powder became available, the same basic technique was applied to these, to produce the Distaloy A grades, which now are most popular. Ho ¨gana ¨s continues to improve and refine the production techniques and to come up with compositions for new applications. The properties and the metallurgy of Distaloy-based materials have been thoroughly studied by metallurgists at Ho ¨gana ¨s and at PM laboratories throughout the world, and new results are still being reported with respect to both applications and fundamental properties. A parameter of great relevance is of course the cost of raw materials and much effort is going into finding more cost effective ways of achieving the desired results.

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This paper discusses changes in land and vegetation cover and natural resources of the Cape Verde Islands since their colonisation. This isolated group of islands in mid-Atlantic was first colonised by the Portuguese around 1460. The paper discusses both physical and human causes of land-cover changes, including changes in climate, land-use, land tenure, economic, political and social systems.The actual consequences of the first centuries of European colonisation of the Cape Verde Islands were very different from the idealised view of tropical islands as Gardens of Eden that was current in Europe during the early colonial period. The sources discussed in this paper provide evidence of catastrophic degradation of the land and vegetation of these islands: from a dry but 'wellwooded' savanna with 'great quantity of grass', and 'streamlets of water' at the time of colonisation to a near desert landscape today, especially at the lower altitudes. A major cause of this degradation, perhaps indirect but still decisive, may have been a political and economic system that permitted an appallingly shortsighted exploitation of the land. The major direct mechanism of this process was probably overexploitation of the vegetation-cover by people and their goats.Despite the evidence for human causes behind this ecological disaster, the possibility cannot be excluded that there has also been a change in climate purely due to physical causes. If, however, the first colonisers had been conscious of the fragility of the ecosystem they came to occupy, these islands could still have profited from the advantages of a dry savanna with trees and a continuous grass cover, as do the Bermudas, which have remained a 'terrestrial paradise' thanks to the protection of the cedar forests since their first settlement in 1622. The reason why the 'fortunate' islands of Cape Verde should be reafforested thus becomes evident.Human beings frequently have a good perception of the symptoms of environmental degradation, but they rarely perceive the causes of such changes.