378 résultats pour "métal"
-
architecture (technique).
De nombreuses régions du monde permettent l'extraction de pierre, dont la dureté et la résistance au gel sont variables. Le bois, plus facile à obtenir et à mettre en œuvre, a longtemps été un matériau privilégié. Dans les pays occidentaux, son usage est aujourd'hui limité à la charpente et aux huisseries. La terre séchée (pisé) ou cuite (brique) supplée la rareté ou l'absence de ces matériaux dans de nombreuses régions. Le métal est utilisé depuis l'Antiquité comme élément de liaison dans la ma...
-
mines, exploitation des.
atteindre 290 tonnes. Des pelleteuses plus petites chargent ensuite le charbon directement dans les camions. Le principal avantage de l'exploitation à ciel ouvert par rapport à l'exploitation souterraine est l'énorme gain de temps et de main-d'œuvre. Le rendement par homme-poste dans les mines à ciel ouvert est trois à quatre fois celui des mines souterraines. Dans les exploitations souterraines, on atteint la couche de charbon par des puits verticaux ou inclinés ou, si le gisement est situé dan...
- bts automatisme rapport
-
Définition du terme:
COURONNÉ, -ÉE, participe passé et adjectif.
de Naboth, 1862, page 33. SYNTAXE :, EXPR., Duc, empereur, roi couronné. Tête couronnée. Souverain, monarque (confer couronnant II A). — Spécialement. RELIGION. — [En parlant du Christ] Couronné d'épines. Notre-Seigneur assis et couronné d'épines (FÉLIX ANTOINE PHILIBERT DUPANLOUP, Journal intime, 1864, page 258 ). Substantif. Institut et musée (...) Decamps, Samson; le couronné d'épines du Titien (JULES MICHELET, Journal, 1845, page 595 ). · Par comparaison. Amour, tu es une passion, mais passi...
-
nucléaires, armes
1
PRÉSENTATION
nucléaires, armes, engins explosifs conçus pour produire instantanément une grande quantité d'énergie nucléaire et utilisés comme armes de guerre.
3.2. 3 Matière fissile 3.2.3. 1 Isotopes de l’uranium L’uranium-235, isotope fissile de l’uranium, ne représente que 0,7 p. 100 de l’uranium naturel ; le reste est constitué d’uranium-238, plus lourd. Aucun procédé chimique ne permet de séparer l’uranium-235 de l’uranium naturel, car ces deux isotopes ont des propriétés chimiques identiques. Plusieurs techniques ont cependant été mises au point pour les séparer, toutes fondées sur l’utilisation de l’infime différence de poids entre les deux is...
-
Définition du terme:
COURONNE, substantif féminin.
En disant ces paroles, il posa sur ma tête la couronne de laurier (STÉPHANIE FÉLICITÉ DUCREST DE SAINT-AUBIN, COMTESSE DE GENLIS, Les Chevaliers du Cygne, tome 2, 1795, page 229 ). SYNTAXE : Couronne civique. Couronne de chêne vert offerte à celui qui, dans un combat, avait sauvé la vie d'un citoyen. Quand par le salut de quelque frère il a droit à la couronne civique (...) qu'il s'asseoie alors parmi les conquérants, et qu'il attende avec confiance le prix de sa valeur (SAINT- MARTIN, Homme dés...
-
Book
I
INTRODUCTION
Kelmscott Chaucer
The Kelmscott Chaucer was published in 1896 by William Morris' company, the Kelmscott Press.
B Medieval European Books Illustration of Saint Mark in the Ebbo GospelsThis is a page from the illuminated manuscript known as the Ebbo Gospels (about 816-835). It depicts Saint Mark lookingheavenward for inspiration as he writes his gospel account, and is drawn in an expressive, energetic style typical ofmedieval art of that period. The full name of the Ebbo Gospels is the Gospel Book of Archbishop Ebbo of Reims. This pagemeasures about 25 by 20 cm (about 10 by 8 in).Bridgeman Art Library, Lo...
- techniques, histoire des
-
-
architecture métallique.
4 MODERNITÉ DU MÉTAL : L’ASSOCIATION AUX TECHNOLOGIES DE POINTE Au XXe siècle, le fer (mis à l’abri de la corrosion par un enrobage de ciment) prête sa souplesse et sa résistance au béton armé. La matière et la masse du béton armé s’opposent pourtant à l’esthétique du métal, lequel vainc l’oxydation et gagne en légèreté grâce à de nouveaux procédés et alliages. La trilogie acier-béton-verre, magistralement explorée par Le Corbusier et Ludwig Mies van der Rohe, triomphe internationalement dans...
-
chauffage, ventilation et climatisation.
chauffage à la vapeur fut inventé vers 1850. 2.2. 1 Principe Les systèmes de chauffage central fournissent de la chaleur à partir d'une ou de plusieurs chaudières à un seul bâtiment ou à un groupe d'habitations. Le terme chauffage urbain s'applique aux systèmes dans lesquels un grand nombre d'immeubles sont alimentés en vapeur par une salle de chaudières centrale gérée par un service public. La chaleur est véhiculée par la vapeur d'eau, l'eau chaude ou l'air (fluides caloporteurs), par effet de...
-
Air - chemistry.
lighting systems, fertilizers, and semiconductors (substances used to make the chips in computers, calculators, televisions, microwave ovens, and many other electronicdevices). A Oxygen More than half of the oxygen produced in the United States is used by the steel industry, which injects the gas into basic oxygen furnaces to heat and produce steel(see Iron and Steel Manufacture: Basic Oxygen Process ). Metalworkers also combine oxygen with acetylene to produce high-temperature torch flames th...
-
Souvent considérée comme un volet secondaire de l'histoire proprement dite, l'histoire
des techniques n'a suscité la création que d'un petit nombre de chaires magistrales et ne fait
pas l'objet de multiples publications.
repos – ce qui empêcha pendant deux millénaires toute possibilité d'établissement d'une dynamique cohérente (étude des mouvements sous l'effet des forces qui les produisent). Il fallut attendre 1687 pour que Newton établisse que la charge tractée s'arrêtait sous l'effet des forces de frottement, mais qu'un corps libre et non sollicité dans l'espace décrivait, quant à lui, un mouvement rectiligne uniforme, inaugurant ainsi l'approche de la dynamique théorique et de l'ensemble de la mécanique r...
-
Dentistry.
Together with dentists, dental hygienists and dental assistants make up the team that provides dental care to patients. Hygienists record patient medical histories, suchas blood pressure and pulse. They clean teeth, apply sealants and fluoride treatments, teach patients sound oral hygiene practices, and often assist with X rays. Manyhygienists receive a two-year associate degree, while others may choose to enroll in a four-year program at a university or in a master’s degree program. There are25...
-
Burkina Faso - country.
powers to promote the welfare of the people. The Lobi live in the southwest as farmers and hunters. Defiant of newcomers, they live in small terraced fortifications. The Bobo are chiefly farmers, artisans, and metalworkers living in large villages in the west-central part of the country. The Gourounsi are mainly artisans and farmers in the south-central areas. Their society is lesshighly structured than that of the other Voltaic groups. Christianity has made substantial inroads among them. The M...
-
Thomas Edison.
While Edison was working on the electric light, he made a scientific discovery that would become important to future generations. Edison noticed that particles of carbonfrom the filament blackened the insides of his light bulbs. This effect was caused by the emission of electrons from the filament, although Edison made the discoverybefore he and other scientists knew the electron existed. Not until 1897 did British physicist J. J. Thomson prove that the blackening observed by Edison was caused b...
-
Thomas Edison - USA History.
While Edison was working on the electric light, he made a scientific discovery that would become important to future generations. Edison noticed that particles of carbonfrom the filament blackened the insides of his light bulbs. This effect was caused by the emission of electrons from the filament, although Edison made the discoverybefore he and other scientists knew the electron existed. Not until 1897 did British physicist J. J. Thomson prove that the blackening observed by Edison was caused b...
-
-
Mesopotamian Art and Architecture
I
INTRODUCTION
Mesopotamian Art and Architecture, the arts and buildings of the ancient Middle Eastern civilizations that developed in the area (now Iraq) between the Tigris and
Euphrates rivers from prehistory to the 6th century
BC.
arts. III EARLY DYNASTIC PERIOD Figures from Tell AsmarCreated around 2700 bc, these stone figures are from the city of Tell Asmar in what today is Iraq. From the Temple ofAbu, the statuettes stood in watchful prayer with the wide, staring eyes often found in Sumerian sculpture. The figuresare in the Iraq Museum, Baghdād, Iraq.Art Resource, NY The first historical epoch of Sumerian dominance lasted from about 3000 BC until about 2340 BC. While earlier architectural traditions continued, a ne...
-
Air Pollution.
Several pollutants attack the ozone layer. Chief among them is the class of chemicals known as chlorofluorocarbons (CFCs), formerly used as refrigerants (notably in airconditioners), as agents in several manufacturing processes, and as propellants in spray cans. CFC molecules are virtually indestructible until they reach thestratosphere. Here, intense ultraviolet radiation breaks the CFC molecules apart, releasing the chlorine atoms they contain. These chlorine atoms begin reacting withozone, br...
- Midnighters
-
Atlantic Slave Trade.
members of the planters’ society. Through most of the years of the Atlantic trade, prices for Africans remained favorable in relation to the price of the crops theyproduced. They were, thus, the best economic solution for plantation owners seeking inexpensive labor. The Atlantic slave trade began as a trickle in the 1440s and grew slowly through the 17th century. By 1700, 25,000 slaves, on average, were crossing the Atlantic everyyear. After 1700 the trade grew much more rapidly to a peak in the...
- la nuit des temps de rené barjavel
-
Soccer.
Two assistants, known as linesmen or referees’ assistants, aid the referee. Their primary job is to alert the referee when balls go out of the playing area and to assist inmaking offsides calls (see Rules section below). The assistants carry flags, which they wave when the ball leaves the playing area or use to point to the spot where a foul was committed. V EQUIPMENT Soccer is played with a round leather ball. It is between 68 and 71 cm (27 and 28 in) in circumference and weighs between 396...
-
Modern Art
I
INTRODUCTION
American Gothic
American Gothic was painted by the 20th-century American artist Grant Wood in 1930.
while at the other side a woman in black appears to mourn the end of her participation in the dance. Click on the buttonsto learn more.© Microsoft Corporation. All Rights Reserved. In view of this diversity, it is difficult to define modern art in a way that includes all of 20th-century Western art. For some critics, the most important characteristic ofmodern art is its attempt to make painting and sculpture ends in themselves, thus distinguishing modernism from earlier forms of art that had con...
-
Vermont - geography.
Forests cover 78 percent of Vermont. Most of the trees are deciduous, principally the maple, elm, birch, beech, oak, hickory, ash, cherry, and butternut. The state treeis the sugar maple, which provides Vermont’s famous maple syrup. Conifers are common in some mountain areas and include mainly the white pine, red spruce,hemlock, and cedar. A great variety of ferns have been found within the state. Among the more common wildflowers that grow in Vermont are anemones, arbutuses,violets, lilacs, dai...
-
-
Vermont - USA History.
Forests cover 78 percent of Vermont. Most of the trees are deciduous, principally the maple, elm, birch, beech, oak, hickory, ash, cherry, and butternut. The state treeis the sugar maple, which provides Vermont’s famous maple syrup. Conifers are common in some mountain areas and include mainly the white pine, red spruce,hemlock, and cedar. A great variety of ferns have been found within the state. Among the more common wildflowers that grow in Vermont are anemones, arbutuses,violets, lilacs, dai...
-
Sri Lanka - country.
acacias, and orchids are found in many areas. The animal life of Sri Lanka includes 88 species of mammals, 21 of which are threatened with extinction. The Asian elephant, cheetah, leopard, and several species ofmonkey are endangered and officially protected. The island’s many species of primates include the long-tailed langur, toque macaque, and slender loris. Other mammalsinclude the sloth bear, several species of deer, mongoose, and wild boar. Reptiles are numerous, with 144 known species. Som...
-
La Soudure
5 La Soudure fil de méta l d ' appoin t in de fusion métal de base aspiration du flux électrode consumable arrivée du flux rayon laser --- -métal en fusion ___ plasma bain de fusion bain de fusion métal de base SOUDAGE À LA FLAMME SOUDAGE PAR ARC IMMERGÉ SOUDAGE PAR JET DE PLASMA synthèse, e n 1893 , d ' un carb ur a nt no u vea u et très p erform ant: l'acétylène , un carb ure de calcium h ydrat é. En 1901, le França is Charl es Pica...
- Copper (element) - chemistry.