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1 плотность популяции
1) Biology: population intensity2) Engineering: population density3) Agriculture: population density (напр. микроорганизмов, насекомых-вредителей)4) Oil: density of population5) Genetics: population density (число особей популяции, соотнесённое к размерам занимаемой ею территории)6) Fishery: abundance7) Ecology: animal density, population concentration8) Aviation medicine: housing densityУниверсальный русско-английский словарь > плотность популяции
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2 плотность поголовья скота
1) Agriculture: density of stocking, stock density2) Ecology: animal densityУниверсальный русско-английский словарь > плотность поголовья скота
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3 çifte
1. double, made up of two identical parts: çifte gerdanlı double-chinned. çifte merdiven double stairway. 2. propelled by a pair of oars: üç çifte kayık a caique propelled by three pairs of oars. 3. double-barrel, double-barreled gun. 4. kick made by an animal using both of its hind feet at once. - atmak /a/ (for an animal) to kick (someone, something) using both of its hind feet at once. - dikiş slang 1. repeater (of a class). 2. repeating a class. - dürbün binoculars. - harf print. double letter, ligature. - kavrulmuş 1. Turkish delight that has a hard consistency and that has been cut into small pieces. 2. roasted almonds that have been glazed with sugar. 3. hard-boiled (person). 4. very experienced, (someone) who has seen a lot. 5. (someone) who has undergone a lot of suffering. 6. slang (student) who is repeating a class. - kumrular two inseparable chums. - minare pair of minarets, twin minarets. - sigorta double insurance. - şamdan two-branched candelabrum. - vergi double taxation. - yoğunluk comp. double density. -
4 grand
grand, e [gʀɑ̃, gʀɑ̃d]1. adjectivea. ( = de haute taille) tall• quand il sera grand [enfant] when he grows up• tu es grand/grande maintenant you're a big boy/girl nowd. (en nombre, en quantité) [vitesse, poids, valeur, puissance] great ; [nombre, quantité] large ; [famille] large, bige. ( = intense) [bruit, cri] loud ; [froid, chaleur] intense ; [vent] strong ; [danger, plaisir, pauvreté] greatf. ( = riche, puissant) [pays, firme, banquier, industriel] leadingg. ( = important) great ; [ville, travail] big• je t'annonce une grande nouvelle ! I've got some great news!h. ( = principal) main• la grande difficulté consiste à... the main difficulty lies in...i. (intensif) [travailleur, collectionneur, ami, rêveur] great ; [buveur, fumeur] heavy ; [mangeur] bigj. ( = remarquable) greatk. ( = de gala) [réception, dîner] grandl. ( = noble) [âme] noble ; [pensée, principe] loftym. ( = exagéré) faire de grandes phrases to voice high-flown sentimentsn. ( = beaucoup de) cela te fera (le plus) grand bien it'll do you the world of good• grand bien vous fasse ! much good may it do you!2. adverb3. masculine nouna. ( = élève) senior boyb. (terme d'affection) viens, mon grand come here, sonc. ( = personne puissante) les grands de ce monde men in high places4. feminine nouna. ( = élève) senior girl5. compounds━━━━━━━━━━━━━━━━━The grandes écoles are competitive-entrance higher education establishments where engineering, business administration and other subjects are taught to a very high standard. The most prestigious include « l'École Polytechnique » (engineering), the three « Écoles normales supérieures » (arts and sciences), « l'ÉNA » (the civil service college), and « HEC » (business administration).Pupils prepare for entrance to the grandes écoles after their « baccalauréat » in two years of « classes préparatoires ». → CLASSES PRÉPARATOIRES CONCOURS ÉCOLE NATIONALE D'ADMINISTRATION* * *
1.
grande gʀɑ̃, gʀɑ̃d adjectif1) ( de dimensions importantes) ( en hauteur) tall; (en longueur, durée) long; ( en largeur) wide; (en étendue, volume) big2) (nombreux, abondant) large, biglaver à grande eau — to wash [something] in plenty of running water [légumes]; to wash [something] down [sol]
3) ( à un degré élevé) [rêveur, collectionneur, ami] great; [tricheur, joueur] big; [buveur, fumeur] heavy4) ( important) [découverte, expédition, nouvelle] great; [date] important; [rôle] major; [problème, décision] bigla grande majorité — the great ou vast majority
5) ( principal) main6) ( de premier plan) [société, marque] leading7) (brillant, remarquable) [peintre, vin, cause] great; [cœur, âme] nobleLouis le Grand — Louis the Great; esprit
les grandes classes — École the senior forms GB, the upper classes US
9) ( qualifiant une mesure) [hauteur, longueur, distance, valeur] great; [pointure, quantité, étendue] large; [vitesse] high10) (extrême, fort) [bonté, amitié, danger, intérêt] great; [bruit] loud; [froid] severe; [chaleur] intense; [vent] strong, high; [tempête] big, violentà grands cris — loudly; cas, remède
11) ( de rang social élevé) [famille, nom] great12) ( grandiose) [réception, projet] grand13) ( emphatique) [mot] big; [phrase] high-soundinget voilà, tout de suite les grands mots — there you go, straight off the deep end
2.
3.
adverbe wideouvrir grand ses oreilles — fig to prick up one's ears
4.
nom masculinles cinq grands — Politique the Big Five
5.
en grand locution adverbialePhrasal Verbs:* * *ɡʀɑ̃, ɡʀɑ̃d grand, -e1. adj1) (= de haute taille) tallIl est grand pour son âge. — He's tall for his age.
2) (= aîné)C'est sa grande sœur. — She's his big sister.
3) (= adulte)Il est assez grand pour... — He's old enough to...
4) (= gros, vaste, large) big, large5) (importance, stature) greatC'est un grand ami à moi. — He's a great friend of mine.
les grandes lignes CHEMINS DE FER — the main lines
6) (ampleur, degré)les grands blessés; Les grands blessés ont été emmenés à l'hôpital en hélicoptère. — The severely injured were taken to hospital by helicopter.
7) (intensif)Ça te fera beaucoup de bien d'être au grand air. — It'll be very good for you to be out in the open air.
2. adv3. nm/f1) (= élève, enfant) big boy, big girlIl est chez les grands maintenant. — He's in the senior school now.
C'est une grande, elle peut y aller seule. — She's a big girl now, she can go on her own.
2) (= personnage)4. nm* * *A adj1 ( de dimensions importantes) ( en hauteur) [personne, arbre, tour, cierge] tall; (en longueur, durée) [bras, enjambée, promenade, voyage] long; ( en largeur) [angle, marge] wide; (en étendue, volume) [lac, ville, salle, trou, édifice, paquet] large, big; [tas, feu] big; ( démesuré) [pied, nez, bouche] big; un homme (très) grand a (very) tall man; un grand homme brun, un homme grand et brun a tall dark man; plus grand que nature larger than life; ouvrir de grands yeux to open one's eyes wide;2 (nombreux, abondant) [famille, foule] large, big; [fortune] large; grande braderie big sale; pas grand monde not many people; faire de grandes dépenses to spend a lot of money; il fait grand jour it's broad daylight; laver à grande eau to wash [sth] in plenty of running water [légumes]; to wash [sth] down [sol]; à grand renfort de publicité with much publicity;3 ( à un degré élevé) [rêveur, collectionneur, travailleur, ami, ennemi, pécheur] great; [tricheur, joueur, lâcheur, idiot] big; [buveur, fumeur] heavy; grand amateur de ballet great ballet lover; c'est un grand timide he's very shy; les grands malades very sick people; c'est un grand cardiaque he has a serious heart condition;4 ( important) [découverte, migration, expédition, événement, nouvelle, honneur] great; [date] important; [rôle] major; [problème, décision] big; ( principal) main; c'est un grand jour pour elle it's a big day for her; une grande partie de la maison a large part of the house; une grande partie des habitants many of the inhabitants; la grande majorité the great ou vast majority; ⇒ scène;5 ( principal) main; le grand escalier the main staircase; le grand problème/obstacle the main ou major problem/obstacle; les grands axes routiers the main ou trunk GB roads; les grands points du discours the main points of the speech; les grandes lignes d'une politique the broad lines of a policy;6 ( de premier plan) Écon, Pol [pays, société, industriel, marque] leading; les grandes industries the big industries;7 (brillant, remarquable) [peintre, œuvre, civilisation, vin, cause] great; [cœur, âme] noble; c'est un grand homme he's a great man; les grands écrivains great authors; un grand nom de la musique a great musician; un grand monsieur du théâtre a great gentleman of the stage; Louis/Pierre le Grand Louis/Peter the Great; les grands noms du cinéma/de la littérature indienne the big names of the cinema/of Indian literature; de grande classe [produit] high-class; [exploit] admirable; ⇒ esprit;8 ( âgé) [frère, sœur] elder; [élève] senior GB, older; ( adulte) grown-up; mon grand frère my elder brother; les grandes classes Scol the senior forms GB, the upper classes US; quand il sera grand when he grows up; mes enfants sont grands my children are quite old; une grande fille comme toi! a big girl like you!; 12 ans! tu es assez grand pour te débrouiller 12 years old! you're old enough to cope;9 ( qualifiant une mesure) [hauteur, longueur, distance, poids, valeur, âge] great; [dimensions, taille, pointure, quantité, nombre, étendue] large; [vitesse] high; [kilomètre, mois, heure] good; il est grand temps que tu partes it's high time you were off ou you went;10 (intense, extrême, fort) [bonté, lâcheté, pauvreté, amitié, chagrin, faim, danger, différence, intérêt] great; [bruit] great, loud; [froid] severe; [chaleur] intense; [vent] strong, high; [tempête] big, violent; avec grand plaisir with great ou much pleasure; dans le plus grand secret in great secrecy; d'une grande bêtise/timidité very ou extremely stupid/shy; à ma grande honte/surprise much to my shame/surprise; sans grand espoir/enthousiasme without much hope/enthusiasm; sans grande importance not very important; il n'y a pas grand mal à cela/à faire there isn't much harm in that/in doing; avoir grand faim/soif to be very hungry/thirsty; avoir grand besoin de to be badly in need of; ça te ferait le plus grand bien it would do you a world of good; à grands cris loudly; ⇒ cas, remède;11 ( de rang social élevé) [famille, nom] great; grande dame great lady; la grande bourgeoisie the upper middle class;12 ( grandiose) [réception] grand; grands projets grand designs; avoir grande allure, avoir grand air to look very impressive;13 ( emphatique) [mot] big; [phrase] high-sounding; un grand merci a big thank you; faire de grands gestes to wave one's arms about; et voilà, tout de suite les grands mots there you go, straight off the deep end.B nm,f1 ( enfant) big boy/girl; Scol senior GB ou older pupil; il a fait ça tout seul comme un grand he did it all by himself like a big boy; il fait le ménage comme un grand he does the housework like a grown-up; pour les grands et les petits for old and young alike;C adv wide; ouvrir grand la bouche to open one's mouth wide; ouvrir tout grand les bras to throw one's arms open; les fenêtres sont grand(es) ouvertes the windows are wide open; ouvrir la porte toute grande to open the door wide; ouvrir grand ses oreilles fig to prick up one's ears; ouvrir tout grand son cœur fig to open one's heart; les bottes chaussent grand the boots are large-fitting; leurs vêtements taillent grand their clothes are cut on the large side; voir grand fig to think big.D nm ( pays) big power; ( entreprise) leader, big name; les grands de ce monde the great and the good; Pol the world's leaders; les cinq grands Pol the Big Five; les grands de l'automobile the top car manufacturers; c'est un grand de la publicité he's big in advertising.E en grand loc adv [ouvrir] wide, completely; faire de l'élevage en grand to breed animals on a large scale; quand ils reçoivent, ils font les choses en grand when they entertain they do things on the grand scale or they really go to town○.grand argentier Hist royal treasurer; hum keeper of the nation's purse, Finance minister; le grand art alchemy; grand banditisme organized crime; grand bassin ( de piscine) main pool; Anat upper pelvis; grand cacatois main royal sail; grand caniche standard poodle; le grand capital Écon big money, big investors pl; grand commis de l'État top civil servant; grand coq de bruyère capercaillie; grand corbeau raven; grand couturier couturier; grand débutant absolute beginner; grand duc Zool eagle owl; grand écart Danse, Sport splits (sg); faire le grand écart to do the splits; le grand écran the big screen; grand électeur ( en France) elector who votes in the elections for the French Senate; ( aux États-Unis) presidential elector; grand ensemble high-density housing complex; la vie dans les grands ensembles high-rise living; grand d'Espagne Spanish grandee; grand foc outer jib; grand frais Météo moderate gale; grand hunier main topsail; grand hunier fixe lower main topsail; grand hunier volant upper main topsail; grand invalide civil, GIC civilian who is registered severely disabled; grand invalide de guerre, GIG Prot Soc ex-serviceman who is registered severely disabled; le grand large Naut the high seas (pl); grand magasin Comm department store; grand maître ( aux échecs) grand master; grand maître de l'ordre des Templiers Hist Grand Master of the Knights Templar; grand mât Naut mainmast; le grand monde high society; le Grand Nord Géog the Far North; Grand Œuvre Great Work; grand officier de la Légion d'Honneur high-ranking officer of the Legion of HonourGB; le Grand Orient the Grand Lodge of France; grand panda giant panda; Grand Pardon Day of Atonement; grand patron Méd senior consultant GB, head doctor US; grand perroquet Naut main topgallant sail; grand prêtre Relig, fig high priest; grand prix Courses Aut, Sport grand prix; le grand public the general public; Comm produit grand public consumer product; grand quart Naut six-hour watch; Grand quartier général, GQG Mil General Headquarters, GHQ; grand quotidien Presse big national daily; grand roque Jeux ( aux échecs) castling long; le Grand Siècle Hist the 17th century (in France); grand teint colourfastGB; grand tétras capercaillie; grand tourisme Courses Aut, Aut GT, gran turismo; le Grand Turc the Sultan; grand veneur Chasse master of the hounds; grande Armée Hist Grande Armée (Napoleon's army); grande Baie Australienne Géog Great Australian Bight; la grande banlieue the outer suburbs (pl); Grande Barrière (de Corail) Géog Great Barrier Reef; la grande bleue the sea; la grande cuisine Culin haute cuisine; grande distribution Écon volume retailing; grand école higher education institution; la Grande Guerre Hist the First World War; grande gueule○ loud mouth○; grande hune Naut maintop; la grande muette the army; la grande muraille de Chine Géog the Great Wall of China; grande personne grown-up, adult; la grande presse Presse the popular dailies (pl); grande puissance Pol superpower; grande roue ( de foire) big wheel GB, Ferris wheel US; grande série Comm mass production; fabriqué en grande série mass-produced; grande surface Comm supermarket; grandes eaux fountains; fig ( pleurs) waterworks; dès qu'on la gronde, ce sont les grandes eaux the minute you tell her off, she turns on the waterworks; grandes lignes Rail main train routes; grandes marées spring tides; grandes ondes Radio long wave (sg); Grandes Plaines Géog Great Plains; les grands blessés the seriously injured; grands corps de l'État Admin senior branches of the civil service; grands espaces Écol open spaces; grands fauves Zool big cats; grands fonds Naut ocean depths; les grands froids the cold of winter; Grands Lacs Géog Great Lakes; grands singes Zool great apes; ⇒ école, voyage.ⓘ Grande école A prestigious third-level institution where admission is usually by competitive entrance examination or concours. Places are much sought after as they are widely considered to guarantee more promising career prospects than the standard university institutions. Many grandes écoles specialize in particular disciplines or fields of study, e.g. ENA, Sciences Po, etc.( féminin grande) [grɑ̃, grɑ̃d] (devant nom masculin commençant par voyelle ou h muet [grɑ̃t]) adjectifA.[ASPECT QUANTITATIF]grand A/B/C capital A/B/Cune grande tour a high ou tall towerun grand fleuve a long ou big riveravoir de grands pieds to have big ou large feetmarcher à grands pas to walk with great ou long strides3. [d'un certain âge - être humain] big[aîné - frère, sœur] big4. [qui dure longtemps] long5. [intense, considérable] greatpendant les grandes chaleurs in high summer, in ou at the height of summerun grand incendie a major ou great firela grande majorité de the great ou vast majority ofils plongent à une grande profondeur they dive very deep ou to a great depth7. [entier]elle m'a fait attendre une grande heure/semaine she made me wait a good hour/a good week9. GÉOGRAPHIE10. ZOOLOGIEB.[ASPECT QUALITATIF]les grands problèmes de notre temps the main ou major ou key issues of our timece sont de grands amis they're great ou very good friendsles grands blessés/brûlés/invalides the seriously wounded/burned/disabled3. [puissant, influent - banque] top ; [ - industriel] top, leading, major ; [ - propriétaire, famille] important ; [ - personnage] great4. [dans une hiérarchie]les grands dignitaires du régime the leading ou important dignitaries of the regime5. [noble]avoir grand air ou grande allure to carry oneself well, to be imposing6. [généralementéreux]il a un grand cœur he's big-hearted, he has a big heart7. [exagéré] biggrands mots high-sounding words, high-flown language8. [fameux, reconnu] greatun grand journaliste a great ou top journalistil ne descend que dans les grands hôtels he only stays in the best hotels ou the most luxurious hotelsle grand film de la soirée tonight's big ou feature filmles grandes dates de l'histoire de France the great ou most significant dates in French history9. HISTOIRE10. [omnipotent, suprême] greatC.[EN INTENSIF]sans grand enthousiasme/intérêt without much enthusiasm/interestsa grande fierté, c'est son jardin he's very proud of ou he takes great pride in his gardenun grand merci à ta sœur lots of thanks to ou a big thank you to your sistercette cuisine a grand besoin d'être nettoyée this kitchen really needs ou is in dire need of a cleantoute la famille au grand complet the whole family, every single member of the familyjamais, au grand jamais je n'accepterai never in a million years will I acceptà sa grande surprise much to his surprise, to his great surprise————————, grande [grɑ̃, grɑ̃d] (devant nom masculin commençant par voyelle ou h muet [grɑ̃t]) nom masculin, nom féminin1. [enfant - d'un certain âge][en appellatif]merci mon grand! thanks, son!allons, ma grande, ne pleure pas! come on now, love, don't cry!comme un grand: je me débrouillerai tout seul, comme un grand/toute seule, comme une grande I'll manage on my own, like a big boy/a big girl[en appellatif]alors, ma grande, tu as pu te reposer un peu? well dear, did you manage to get some rest?[personne de grande taille]pour la photo, les grands se mettront derrière for the photo, tall people ou the taller people will stand at the back————————adverbe1. [vêtement]2. (locution)3. [largement]4. ART————————nom masculin1. PHILOSOPHIE → link=infiniment infiniment2. [entrepreneur, industriel]les grands de l'automobile the major ou leading car manufacturers————————grands nom masculin plurielÉCONOMIE & POLITIQUEles grands [les puissants] the rich (and powerful)les grands de ce monde the people in (positions of) power ou in high places————————en grand locution adverbiale[complètement] on a large scaleil faut aérer la maison en grand the house needs a thorough ou good airinggrande école nom féminingrand ensemble nom masculingrande surface nom fémininThe grandes écoles are relatively small and highly respected higher education establishments. Admission is usually only possible after two years of intensive preparatory studies and a competitive entrance examination. Most have close links with industry. The grandes écoles include l'École des hautes études commerciales or HEC (management and business), l'École polytechnique or l'X (engineering) and l'École normale supérieure (teacher training). -
5 σύστασις
A bringing together, introduction, recommendation, πατρικὴν ἔχων ς. Plb.1.78.1; ἡ πρός τινα ς. Id.4.82.3, cf. SIG591.62 (Lampsacus. ii B.C.), D.H.Rh.5.2, Plu.Them.27;σ. τῆς πρός τινα εὐνοίας J.AJ15
.b.7; care, guardianship, ἔτινηπίας οὔσας ([etym.] ἀπέδωκεν[]) (ii B.C.); power of attorney, PTeb.317.14 (ii A.D.), etc.2 communication between a man and a god,ταῦτα σοῦ εἰπόντος τρίς, σημεῖον ἔσται τῆς συστάσεως τόδε PMag.Par.1.209
, cf. 220,260, al., PMag.Lond.47.1,121.505.II proof, Alex.Aphr.in Metaph.12.3, 409.16; confirmation, εἰς σύστασιν [ τῶν ἀξιωμάτων] καὶ πίστιν ib.271.14;σ. καὶ πίστεις τινός Hermog. Id.1.10
;πρὸς σύστασιν καὶ ἀσφάλειαν ἐπωμοσάμην PLond.1.77.62
(vi A.D.), cf. BGU1187.31 (i B.C.).B ([etym.] συνίσταμαι) standing together, close combat, conflict,ἐν τῇ σ. μάχεσθαι Hdt.6.117
, cf. 7.167; ἡ ἐν ταῖς συμπλοκαῖς μάχη καὶ ς. Pl.Lg. 833a;ἡ ἐκ σ. μάχη Hdn.4.15.3
;ὅταν.. σύστασιν ὁ ἀγὼν ἔχῃ Plu.Demetr.16
, cf. Aem.20: metaph., disturbance in the human body,καθάρσεων καὶ συστάσεων τοῦ σώματος ἀρίστη ἡ διὰ τῶν γυμνασίων Pl. Ti. 89a
;καταστεῖλαι τὴν σ. τὴν ἀπὸ τοῦ γυμνασίου Antyll.
ap. Orib.6.26.5; σ. ὅλου τοῦ σώματος (as a plague-symptom) Ruf. ap. eund.44.17.2; ξ. τῆς γνώμης conflict of mind, intense anxiety, Th.7.71;μένος μὲν ξ. τε σῶν φρενῶν δεινή E.Hipp. 983
; soἤν τις πόνος ἢ σ. γίνηται τῷ ἀνθρώπῳ Hp.Morb.Sacr.17
vulg. (f.l. for τάσις).2 meeting, accumulation, e.g. of humours,σ. οὑγροῦ περὶ τὴν ὑπερῴην Id.Coac. 233
; of water. Thphr.CP5.14.5 (pl.), cf. D.S.3.36; of winds, ib. 51, POxy.1768.9 (iii A.D., dub.): metaph., ; combination,τραγῳδίαν.. εἶναι τὴν τούτων σ. πρέπουσαν ἀλλήλοις Id.Phdr. 268d
.3 knot of men assembled, E.Andr. 1088 (pl.), Heracl. 415 (pl.); [full] κατὰ ξυστάσεις γιγνόμενοι forming into knots, Th.2.21, cf. X. Eq.7.19.b political union, more general than ἑταιρεία or σύνοδος, Isoc.3.54, cf. D.45.67; ἐθνικαὶ ς. national unions, Plb.23.1.3;κατὰ συστάσεις κωμάζειν D.C.Fr.39.7
.II composition, structure, constitution of a person or a thing,τῶ κόσμω Ti.Locr.99d
, cf. Pl.Ti. 32c; τῶν ὡρῶν, τῆς ψυχῆς, Id.Smp. 188a, Ti. 36d; of the parts of an animal, Arist.PA 646a20, GA 744b28, al.;σώματος Sor.1.111
;τῶν ἀτόμων Epicur.Nat.35
G.; ἡ περὶ τὴν κεφαλὴν ς. Pl.Ti. 75b; φυσικὴ ς. Arist. Cat. 9b18;ἡ σ. τῆς πόλεως Id.Pol. 1295b28
, cf. 1332a30;τῶν πραγμάτων Id.Po. 1450a15
; τοῦ μύθου ib. 1452a18; abs., plot of a drama, ib. 1453a31;τὴν σ. ἔχειν ἐκ τοῦ ψεύδους Phld.Rh.1.361
S.; περὶ τρόπων συστάσεως, title of work by Chrysipp.; προσώπου ς. expression of face, Plu.Per.5.b abs., political constitution, Pl.R. 546a, Lg. 702d, etc.c χωρίον ἀμπελικὸν ἐν συστάσει ἀρουρῶν ὅσων ἐστίν consisting of.., PGiss.56.7 (vi A.D.).2 coming into existence, formation, , cf. c;πόλεων σ. καὶ φθοράς Id.Lg. 782a
; ἡ ἐξ ἀρχῆς τῶν ὅλων ς. D.S.1.7, cf. Plu.2.427b;τὴν σ. λαμβάνειν Arist.HA 547b14
, Plb.6.4.13, etc.; of a river,τὴν ἀρχὴν τῆς σ. λαμβάνειν Id.9.43.1
;σ. ἐπιβουλῆς Id.6.7.8
.3 of bodies, density or consistency, πυκνότης καὶ ς., opp. ὑγρότης καὶ διάχυσις, Thphr.Vent. 58;σ. καὶ πῆξις Plu.2.130b
; degree of solidity, consistency,σπέρμα.. τρυφερὰν ἔτι καὶ νεοπαγῆ τὴν σ. ἔχον Sor.1.46
, cf. 58; solid knot or lump, [ μαστοὶ] θρομβώδεις συστάσεις ἔχοντες ib.88;μέχρι συστάσεως ἐμπλαστρώδους ἑψηθέν Gal.11.134
, cf. 6.249, Dsc.3.7;τὰ ὑδατωδῶς ὑγρὰ πάχος καὶ σ. μηδεμίαν ἔχοντα Gal.16.761
; λεαίνεται μέχρι ς. Orib.Fr.55.4 a substance, πλάττειν ἐκ πηλοῦ ζῷον ἤ τινος ἄλλης ὑγρᾶς ς. Arist.PA 654b30, cf. Plu.2.696a; ξηραὶ ς. Arist.HA 519b19.Greek-English dictionary (Αγγλικά Ελληνικά-λεξικό) > σύστασις
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6 явление электрической дуги
явление электрической дуги
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[Интент]Параллельные тексты EN-RU
Electric arc phenomenon
The electric arc is a phenomenon which takes place as a consequence of a discharge which occurs when the voltage between two points exceeds the insulating strength limit of the interposed gas; then, in the presence of suitable conditions, a plasma is generated which carries the electric current till the opening of the protective device on the supply side.
Gases, which are good insulating means under normal conditions, may become current conductors in consequence of a change in their chemical-physical properties due to a temperature rise or to other external factors.
To understand how an electrical arc originates, reference can be made to what happens when a circuit opens or closes.
During the opening phase of an electric circuit the contacts of the protective device start to separate thus offering to the current a gradually decreasing section; therefore the current meets growing resistance with a consequent rise in the temperature.
As soon as the contacts start to separate, the voltage applied to the circuit exceeds the dielectric strength of the air, causing its perforation through a discharge.
The high temperature causes the ionization of the surrounding air which keeps the current circulating in the form of electrical arc. Besides thermal ionization, there is also an electron emission from the cathode due to the thermionic effect; the ions formed in the gas due to the very high temperature are accelerated by the electric field, strike the cathode, release energy in the collision thus causing a localized heating which generates electron emission.
The electrical arc lasts till the voltage at its ends supplies the energy sufficient to compensate for the quantity of heat dissipated and to maintain the suitable conditions of temperature. If the arc is elongated and cooled, the conditions necessary for its maintenance lack and it extinguishes.
Analogously, an arc can originate also as a consequence of a short-circuit between phases. A short-circuit is a low impedance connection between two conductors at different voltages.
The conducting element which constitutes the low impedance connection (e.g. a metallic tool forgotten on the busbars inside the enclosure, a wrong wiring or a body of an animal entered inside the enclosure), subject to the difference of potential is passed through by a current of generally high value, depending on the characteristics of the circuit.
The flow of the high fault current causes the overheating of the cables or of the circuit busbars, up to the melting of the conductors of lower section; as soon as the conductor melts, analogous conditions to those present during the circuit opening arise. At that point an arc starts which lasts either till the protective devices intervene or till the conditions necessary for its stability subsist.
The electric arc is characterized by an intense ionization of the gaseous means, by reduced drops of the anodic and cathodic voltage (10 V and 40 V respectively), by high or very high current density in the middle of the column (of the order of 102-103 up to 107 A/cm2), by very high temperatures (thousands of °C) always in the middle of the current column and – in low voltage - by a distance between the ends variable from some microns to some centimeters.
[ABB]Явление электрической дуги
Электрическая дуга между двумя электродами в газе представляет собой физическое явление, возникающее в тот момент, когда напряжения между двумя электродами превышает значение электрической прочности изоляции данного газа.
При наличии подходящих условий образуется плазма, по которой протекает электрический ток. Ток будет протекать до тех пор, пока на стороне электропитания не сработает защитное устройство.
Газы, являющиеся хорошим изолятором, при нормальных условиях, могут стать проводником в результате изменения их физико-химических свойств, которые могут произойти вследствие увеличения температуры или в результате воздействия каких-либо иных внешних факторов.
Для того чтобы понять механизм возникновения электрической дуги, следует рассмотреть, что происходит при размыкании или замыкании электрической цепи.
При размыкании электрической цепи контакты защитного устройства начинают расходиться, в результате чего постепенно уменьшается сечение контактной поверхности, через которую протекает ток.
Сопротивление электрической цепи возрастает, что приводит к увеличению температуры.
Как только контакты начнут отходить один от другого, приложенное напряжение превысит электрическую прочность воздуха, что вызовет электрический пробой.
Высокая температура приведет к ионизации воздуха, которая обеспечит протекание электрического тока по проводнику, представляющему собой электрическую дугу. Кроме термической ионизации молекул воздуха происходит также эмиссия электронов с катода, вызванная термоэлектронным эффектом. Образующиеся под воздействием очень высокой температуры ионы ускоряются в электрическом поле и бомбардируют катод. Высвобождающаяся, в результате столкновения энергия, вызывает локальный нагрев, который, в свою очередь, приводит к эмиссии электронов.
Электрическая дуга длится до тех пор, пока напряжение на ее концах обеспечивает поступление энергии, достаточной для компенсации выделяющегося тепла и для сохранения условий поддержания высокой температуры. Если дуга вытягивается и охлаждается, то условия, необходимые для ее поддержания, исчезают и дуга гаснет.
Аналогичным образом возникает дуга в результате короткого замыкания электрической цепи. Короткое замыкание представляет собой низкоомное соединение двух проводников, находящихся под разными потенциалами.
Проводящий элемент с малым сопротивлением, например, металлический инструмент, забытый на шинах внутри комплектного устройства, ошибка в электромонтаже или тело животного, случайно попавшего в комплектное устройство, может соединить элементы, находящиеся под разными потенциалами, в результате чего через низкоомное соединение потечет электрический ток, значение которого определяется параметрами образовавшейся короткозамкнутой цепи.
Протекание большого тока короткого замыкания вызывает перегрев кабелей или шин, который может привести к расплавлению проводников с меньшим сечением. Как только проводник расплавится, возникает ситуация, аналогичная размыканию электрической цепи. Т. е. в момент размыкания возникает дуга, которая длится либо до срабатывания защитного устройства, либо до тех пор, пока существуют условия, обеспечивающие её стабильность.
Электрическая дуга характеризуется интенсивной ионизацией газов, что приводит к падению анодного и катодного напряжений (на 10 и 40 В соответственно), высокой или очень высокой плотностью тока в середине плазменного шнура (от 102-103 до 107 А/см2), очень высокой температурой (сотни градусов Цельсия) всегда в середине плазменного шнура и низкому падению напряжения при расстоянии между концами дуги от нескольких микрон до нескольких сантиметров.
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Русско-английский словарь нормативно-технической терминологии > явление электрической дуги
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