Âge du bronze

L’âge du bronze est la période de la Protohistoire et de l'Histoire caractérisée par l'existence de la métallurgie du bronze, nom générique des alliages de cuivre et d'étain. L'âge du bronze succède au Néolithique final et précède l'âge du fer dans de nombreuses régions de l'Ancien Monde. Schématiquement, dans les régions du monde où il est significatif et étudié (Moyen-Orient, Europe, Afrique du Nord, Asie), l'âge du bronze s'étend sur une période de près de deux mille ans, de 2700 à , mais avec de grandes variations selon les aires géographiques considérées. En Amérique, les civilisations précolombiennes connurent une métallurgie de l'or et du cuivre jusqu'à la conquête espagnole, mais peu de métallurgie du bronze. Archéologie thumb|upright=1.3|alt=|Parure en bronze de Penne (Tarn) - Muséum de Toulouse. Les précurseurs Antoine de Jussieu En 1723, Antoine de Jussieu fut le premier à publier ses travaux de recherche sur les artéfacts archéologiques

À propos de ce résultat

Cette page est générée automatiquement et peut contenir des informations qui ne sont pas correctes, complètes, à jour ou pertinentes par rapport à votre recherche. Il en va de même pour toutes les autres pages de ce site. Veillez à vérifier les informations auprès des sources officielles de l'EPFL.

Publications associées (8)

Publications associées

Chargement

Personnes associées

Chargement

Unités associées

Chargement

Concepts associés (130)

Concepts associés

Chargement

Cours associés (12)

Cours associés

Chargement

Séances de cours associées (16)

Séances de cours associées

Chargement

Influence of Ta and Ti Doping on the High Field Performance of (Nb,Ta,Ti)(3)Sn Multifilamentary Wires based on Osprey Bronze with High Tin Content

Davide Uglietti

Ta and Ti are the most widely used additions for technical Nb3Sn multifilamentary superconductors. These elements are known to influence grain growth, grain morphology and chemical composition in the A15 layer, hence the current carrying properties of the wires over a wide magnetic field range. So far only few studies tried to compare systematically Ta and Ti doped and undoped Nb3Sn wires in the frame of the same work, down to a nanometric scale. We present an investigation on several multifilamentary (Nb,Ta,Ti)3Sn bronze route wires, fabricated at a laboratory scale, with various amounts of additives. The wires consist of fine filaments embedded in a Cu-Sn or Cu-Sn-Ti Osprey bronze with > 15 wt.% Sn and an external Cu stabilization. Microstructural observations are compared with the results of Jc and n values measured up to 21 T at 4.2 and 2.2 K, and for longitudinal strains up to 0.5%. Non-Cu Jc values up to 300 Amm-2 and n values up to 50 at 17 T and 4.2 K show clearly that wires with Ti addition to the bronze have a better performance with respect to wires with Ti additions to the filaments.

Institute of Physics Publishing2006

Chargement

Infiltration of tin bronze into alumina particle beds: influence of alloy chemistry on drainage curves

Alain Léger, Andreas Mortensen, Ludger Weber

The wetting of angular alumina particle preforms by Cu-Sn alloys is investigated by means of pressure infiltration experiments conducted at 1150 A degrees C, using a system enabling dynamic and precise measurements of the metal volume injected into the preform. Wetting is quantified in terms of drainage curves, which plot the volume fraction of molten metal in the packed powder preform (also called saturation) versus the applied pressure. The shape of the curves confirms earlier findings, namely (i) the initial stage of infiltration is dominated by percolation and obeys a universal scaling relation while the metal shape is fractal; and (ii) at higher saturation, incremental pore-filling is dictated by local pore geometrical characteristics, saturation curves obeying then the Brooks-Corey correlation. According to sessile drop data in the literature, the Cu-Sn system is characterized by relatively small changes in the contact angle with alloy composition (128A degrees-122A degrees), while the metal surface tension changes by more than a factor two over the whole composition range. One would, therefore, expect that the drainage curves be indifferently proportional to the molten metal surface tension or the work of immersion: the present data show that this is indeed verified.

Springer Verlag2014

Chargement

Characterizing in-text citations in scientific articles: A large-scale analysis

Giovanni Colavizza

We report characteristics of in-text citations in over five million full text articles from two large databases – the PubMed Central Open Access subset and Elsevier journals – as functions of time, textual progression, and scientific field. The purpose of this study is to understand the characteristics of in-text citations in a detailed way prior to pursuing other studies focused on answering more substantive research questions. As such, we have analyzed in-text citations in several ways and report many findings here. Perhaps most significantly, we find that there are large field-level differences that are reflected in position within the text, citation interval (or reference age), and citation counts of references. In general, the fields of Biomedical and Health Sciences, Life and Earth Sciences, and Physical Sciences and Engineering have similar reference distributions, although they vary in their specifics. The two remaining fields, Mathematics and Computer Science and Social Science and Humanities, have different reference distributions from the other three fields and between themselves. We also show that in all fields the numbers of sentences, references, and in-text mentions per article have increased over time, and that there are field-level and temporal differences in the numbers of in-text mentions per reference. A final finding is that references mentioned only once tend to be much more highly cited than those mentioned multiple times.

2018

Chargement

Néolithique

vignette|Un village néolithique sur palafittes reconstitué, sur le lac de Constance, près de Unteruhldingen, en Allemagne. Le Néolithique (parfois nommé « âge de la pierre polie »), qui succède au Mé

Égypte antique

vignette|redresse=2|Principaux sites de l'Égypte antique. L'Égypte antique est une ancienne civilisation du nord-est de l'Afrique, concentrée le long du cours inférieur du Nil, dans ce qui constitue

Âge du fer

vignette|redresse=1.5|Reconstitution d'une maison de l'âge du fer au , Royaume-Uni. L’âge du fer est une période archéologique caractérisée par la métallurgie du fer et faisant généralement suite à l

MSE-234: Mechanical behaviour of materials

Ce cours est une introduction au comportement mécanique, à l'élaboration, à la structure et au cycle de vie des grandes classes de matériaux de structure (métaux, polymères, céramiques et composites)

MSE-422: Advanced metallurgy

This course covers the metallurgy, processing and properties of modern high-performance metals and alloys (e.g. advanced steels, Ni-base, Ti-base, High Entropy Alloys etc.). In addition, the principles of computational alloy design as well as approaches for a sustainable metallurgy will be addressed

PHYS-405: Experimental methods in physics

The course's objectivs are: Learning several advenced methods in experimental physics, and critical reading of experimental papers.