Using the present to interpret the past: the role of ethnographic studies in Andean archaeology

Within Andean research it is common to use ethnographic analogies to aid the interpretation of archaeological remains, and ethnographers and archaeologists have developed shared research in technology, material culture and material practice. Although most of this research does not follow the detailed recording methods of spatial patterning envisioned in earlier formulations of ethnoarchaeology, it has had a profound effect on how archaeology in the region has been interpreted. This paper uses examples from the study of pottery production to address earlier debates about the use of ethnographic analogy, discusses the dangers of imposing an idealised or uniform vision of traditional Andean societies onto earlier periods (‘Lo Andino’) but stresses the benefits of combining ethnographic and archaeological research to explore continuities and changes in cultural practice and regional variations

Calcul des pertes par courants induits dans les conducteurs statoriques des machines asynchrones sans fer

Statoric windings of electrical machines are generally made out of Roebell bars and, less frequently, of twisted conductor bars. The a.c. component of the magnetic field induces eddy currents within each elementary conductor and also induces currents which circulate between different conductors of the same bar. These currents are calculated, in the case of ironless asynchronous machines, using a computer simulation previously developed for such machines [1]. These calculations show that the eddy current losses, and the losses due to the induced circulating currents can always be made negligible with a good choice of the conductors.Les bobinages statoriques des machines sont généralement constitués de barres Roebell et plus rarement de barres torsadées. Le champ magnétique alternatif auquel ils sont soumis engendre des courants de Foucault locaux et, à l'intérieur des barres, des courants de circulation entre les différents conducteurs qui la constituent. On calcule ces courants dans le cas des machines sans fer en utilisant la modélisation des champs précédemment mise en place pour ces machines [1]. On montre ainsi que les pertes par courants de Foucault et par courants de circulation peuvent toujours être rendues négligeables par un choix approprié des conducteurs

Calcul des pertes par courants induits dans les conducteurs statoriques des machines asynchrones sans fer

Les bobinages statoriques des machines sont généralement constitués de barres Roebell et plus rarement de barres torsadées. Le champ magnétique alternatif auquel ils sont soumis engendre des courants de Foucault locaux et, à l'intérieur des barres, des courants de circulation entre les différents conducteurs qui la constituent. On calcule ces courants dans le cas des machines sans fer en utilisant la modélisation des champs précédemment mise en place pour ces machines [1]. On montre ainsi que les pertes par courants de Foucault et par courants de circulation peuvent toujours être rendues négligeables par un choix approprié des conducteurs

Allergies alimentaires rares [Rare food allergies]

A limited number of foods explain the majority of food allergies. These allergies can be due to a weak allergenicity (garlic, onion, potato), or a weak (or increasing) exposure to emergent food allergens which can be imported (exotic fruits), or recently introduced (lupin, buckwheat, sesame, inulin) or modified by the industry (lysats, lecithins, traces of antibiotics, caseinates, molds, dust mite). Others are in relation with rarer cross-reactivity food allergy syndrome (Apiaceae-Compositae-mugwort syndrome, egg-bird syndrome, cat epithelium-pork meat syndrome). Others are rarely identified, because the food is masked (pepper, basilic). We illustrate rare cases of food allergy and discuss the diagnostic management which is based on a meticulous patient history. Un nombre restreint d'aliments explique la majorité des allergies alimentaires. Les allergies alimentaires rares sont dues à une faible allergénicité (ail, oignon, pomme de terre) ou à une exposition faible ou croissante à des aliments émergents, importés (fruits exotiques), introduits (lupin, sarrasin, sésame, inuline), ou modifiés par l'industrie (lysats, lécithines, traces d'antibiotiques, caséinates, moisissures, acariens). D'autres sont en relation avec des croisements d'allergènes rares (syndrome croisé ombellifères-composées-armoise, syndrome oeuf-oiseau, syndrome épithélium de chat-viande de porc). D'autres enfin sont rarement identifiées, car l'allergène est masqué (poivre, basilic). Nous décrivons des cas rares illustratifs et rappelons la démarche diagnostique qui s'appuie sur une anamnèse minutieuse

New considerations for modelling a MED-TVC plant under dynamic conditions

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New considerations for modelling a MED-TVC plant under dynamic conditions

The multiple-effect distillation (MED) technology is nowadays the most promising desalination process to be coupled with variable heat sources, thus leading to a more sustainable way to produce water. In order to prove the potential of this, it is of major interest to develop powerful modelling tools to predict the performance of this coupling. Only a few models have been presented so far. They show promising results but were based on some simplifying assumptions and non-physical constraints that could limit the analysis of the dynamic behaviour of a MED plant. This paper presents new considerations for the dynamic modelling of a MED plant associated with a thermal vapour compression unit, starting from a previous work “A dynamic model for MED-TVC transient operation”. After several improvements, this model is now more representative of the real operating modes of a MED-TVC plant by considering real process inputs. This paper also highlights the importance of accurately modelling the interconnection between effects, the evaporation and condensation processes and the other components, such as the pre-heaters. Here is also presented a control strategy for operating a MED plant under dynamic conditions. Indeed, when a perturbation occurs in the motive steam pressure, it is possible to stabilize the whole plant by a simultaneous variation in the intake seawater mass flow rate at the final condenser. The model has been validated in steady-state conditions with experimental data from a MED-TVC plant operated in Trapani (Sicily) and was used to perform dynamic simulation to prove the feasibility of operating a MED-TVC plant under dynamic conditions, which is a major step toward proving the possibility of a coupling with renewable energies