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ABSTRACT:Mining and underground archaeology are two domains of expertise where three-dimensional data take an important part in the associated researches. Up to now, archaeologists study mines and underground networks from line-plot surveys, cross-section of galleries, and from tool marks surveys. All this kind of information can be clearly recorded back from the field from threedimensional models with a more cautious and extensive approach. Besides, the volumes of the underground structures that are very important data to explain the mining activities are difficult to evaluate from "traditional" hand-made recordings. They can now be calculated more accurately from a 3D model. Finally, reconstructed scenes are a powerful tool as thinking aid to look back again to a structure in the office or in future times. And the recorded models, rendered photo-realistically, can also be used for cultural heritage documentation presenting inaccessible and sometimes dangerous places to the public. Nowadays, thanks to modern computer technologies and highly developed software tools paired with sophisticated digital camera equipment, complex photogrammetric processes are available for moderate costs for research teams. Recognizing these advantages the authors develop and utilize image-based workflows in order to document ancient mining monuments and underground sites as a basis for further historical and archaeological researches, performed in collaborative partnership during recent projects on medieval silver mines and preventive excavations of undergrounds in France.
In the past, it was crucial to ventilate the old mines, in order to make the miners' work possible. In most mountainous areas, the galleries where equipped with ventilation shafts. However, in many short galleries, such shafts were not bored and air removal was achieved thanks to natural ventilation. It seems that beyond a critical distance, natural ventilation is no longer efficient and the turnover of breathable air is not achieved. The work presented here deals with the physical analysis of air removal in a horizontal mine gallery, using three quantitative approaches. In the first approach, air velocity and temperature measurements were used to establish an empirical expression of the air velocity within the gallery with respect to the temperature difference between the inner and the outer air. This law quantifies the breathable air change rate and gives the distance (of about 50 meters) above which ventilation does not work anymore. The second approach is based on a theoretical analysis which yields the following expression of the air velocity,
where T(out) and T(end) . are respectively the temperatures outside and at the end of the gallery, g is the gravitational acceleration, H is the gallery neight and x is the distance from the gallery entry. In the last approach, the flow field is solved with a commercial CFD (Computational Fluid Dynamics) code based on the finite volume method. Although convergence was not actually reached due to the strong dynamic uncoupling effect between the inner and the outer parts of the gallery, the qualitative results computed with this code are in agreement with the previous ones.
En 1540 est imprimé à Venise le premier livre traitant de toute la métallurgie. Il s'agit de l'ouvrage du signor Vannoccio Biringucio De la pirotechnia. Cet ouvrage paraît un peu avant le célèbre De Re Metallica de Giorgius Agricola (1556). Abordant en dix livres de nombreux sujets et questions pratiques ou métaphysiques, l'ouvrage de Vannoccio Biringuccio fait une place de choix au plomb dont on trouve des mentions plus ou moins développées dans la plupart des livres composant cette « Pirotechnia ».
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