| 释义 |
▪ I. thermal, a.|ˈθɜːməl|
[= F. thermal (Buffon), f. Gr. θέρµη heat + -al1.]
1. Of, pertaining to, or of the nature of thermæ or hot springs; of a spring, etc., (naturally) hot or warm; also, having hot springs.
1756C. Lucas Ess. Waters III. 69 These thermal waters are absolutely colorless. 1800W. Saunders Min. Waters Pref. 17 The thermal waters of Bath or Buxton. Ibid. iv. 352 Enriched with several thermal springs. 1859R. F. Burton Centr. Afr. in Jrnl. Geog. Soc. XXIX. 81 Detached boulders, blackened, probably, by the thermal fumes. 1876M. Collins From Midn. to Midn. III. ix. 169 The thermal city's [Bath's] superb crescents. 1898Allbutt's Syst. Med. V. 1000 Simple thermal baths at 90° F. or under commonly tend to reduce the pulse-rate.
2. a. Of or pertaining to heat; determined, measured, caused, or operated by heat. thermal agitation, the motion of atoms or the like due to their thermal energy; thermal analysis, analysis of a substance by examination of the way its temperature falls on cooling or rises on heating; thermal barrier (Aeronaut.) = heat barrier s.v. heat n. 14 d; thermal bremsstrahlung, electromagnetic radiation produced by the thermal motion of charged particles in a plasma; thermal capacity, the capacity of a body (cf. capacity 1 c, heat n. 2 d) measured by the quantity of heat required to raise its temperature one degree; thermal column (Nucl. Physics), a body of moderator inside or projecting from a reactor such that it serves as a source of thermal neutrons for experimental purposes; thermal cycle, a cycle in which the temperature of a substance rises or falls and then returns to its initial value; thermal cycling, the periodic heating and cooling of a substance; thermal death point, the lowest temperature at which a micro-organism is killed under specified conditions; thermal diffusion, diffusion occurring as a result of the thermal motion of atoms or molecules, esp. as a technique for separating gaseous compounds of different isotopes of an element (which diffuse at different rates in a temperature gradient); thermal diffusivity, the thermal conductivity of a substance divided by the product of its density and its specific heat capacity; thermal efficiency, the efficiency of an engine measured by the ratio of the work done by it to the heat supplied to it; thermal imaging, the technique of using the heat given off by objects or substances to produce an image of them; so thermal imager; thermal lance = thermic lance s.v. thermic a.; thermal noise (Electronics), noise arising from the random thermal motion of electrons; thermal pollution, the production of heat, or the discharge of warm water, esp. into a river or lake, on a scale that is potentially harmful ecologically; thermal printer, a printer having a matrix of fine pins as the print-head, which are selectively heated to form a character on heat-sensitive paper; thermal runaway (Electronics), a dramatic or destructive rise in the temperature of a transistor as a result of an increase in its temperature causing an increase in the current through it, and vice versa; thermal shock (cf. shock n.3 2); thermal storage a system of storing water at high pressure and temperature in vessels above the boilers during hours of low load in electric generating stations; also used attrib. to designate appliances which store heat in other ways; thermal unit, a unit of heat; the British thermal unit is the amount of heat required to raise the temperature of a pound of water at its maximum density through one degree Fahrenheit (abbrev. B.Th.U., B.T.U., B.t.u.).
1837Brewster Magnet. 267 The thermal and the magnetic equators are connected..with the thermal and magnetic poles. 1853Trans. R. Soc. Edin. XX. 170 The mechanical equivalent of the ordinary thermal unit. 1870Tyndall Lect. Electr. §10 To produce both magnetic and thermal phenomena. 1876Catal. Sci. App. S. Kens. Mus. §1056 The heat is calculated as follows, either in calories or British thermal units. 1880W. Thomson in Encycl. Brit. XI. 558/2 Regnault's measurements of the thermal capacity of water at different temperatures. Ibid. 578/1 The thermal conductivity of the substance is not generally the same at different temperatures. Ibid. 581/2 It is k/c, not merely k, that expresses the quantity of the substance on which the phenomenon chiefly depends. We therefore propose to give to k/c the name of thermal diffusivity. 1884Knight Dict. Mech., Suppl. 891/1 Thermal Alarm for Hot Boxes. 1898Public Health Papers & Rep. (Amer. Public Health Assoc.) XXIII. 86 In determining the thermal death point cultures should always be moist. 1910J. G. Horner in Encycl. Brit. IV. 148/2 In some cases where the work required is very intermittent, thermal storage is employed. 1910H. L. Callendar ibid. V. 61/1 The specific heat of a substance is sometimes defined as the thermal capacity of unit mass. Ibid. XIII. 137/1 English Engineers usually state results in terms of the British Thermal Unit (B. Th. U.). Ibid. 138/1 The improvement in thermal efficiency obtained by expansive working. 1916S. Chapman in Proc. R. Soc. A. XCIII. 10 We may call D12, D12′, Dp, and DT respectively the coefficients of diffusion, forced diffusion, pressure diffusion, and thermal diffusion. The definition of D12 agrees with that usually given for the coefficient of diffusion. The other coefficients seem to be defined here for the first time. 1925Jrnl. Iron & Steel Inst. CXII. 489 Thermal analysis was followed by determination of the hardness and a study of the micro⁓structure of the test-pieces. 1925Thermal shock [see pulpal a.]. 1927Physical Rev. XXIX. 367 Ordinary electric conductors are sources of random voltage fluctuations, as a result of thermal agitation of the electric charges of the conductor. 1930F. B. Llewellyn in Proc. IRE XVIII. 244 The importance of this noise, which will be termed ‘thermal noise’, in high-frequency radio receiving circuit design will be discussed. 1932Hardy & Perrin Princ. Optics 142 Thermal radiation is characteristic of the temperature of the radiating body rather than the material of which it is composed. 1933Archit. Rev. Oct. p. xl/1 During the last two or three years an entirely new kind of cooking appliance has made its appearance in England. It is known as the thermal storage or stored heat cooker. 1935Discovery July 214/2 Barometric depressions are discussed..in their modern guise as interacting air masses, the forced ascent necessary to give rain being related to dynamical instability instead of to thermal instability as in the older theories. 1936W. L. Nelson Petroleum Refinery Engin. xvii. 304 The thermal decomposition or cracking of oil was called to our attention by Silliman in 1871. 1943Gloss. Terms Electr. Engin. (B.S.I.) 14 A B.t.u. is equivalent to 1054 joules. 1950Sci. News XV. Plate 16 (caption) Slip⁓lines in pure zinc after exposure to 50 thermal cycles between 30°C and 150°C (× 500). 1950Canad. Jrnl. Res. A. XXVIII. 434 The thermal column of the Chalk River pile was used as a large block of scattering material with a high flux of thermal neutrons. 1951Jrnl. R. Aeronaut. Soc. LV. 757/2 A new barrier is faced after ‘climbing’ the sonic barrier, namely the Thermal Barrier. 1954R. Stephenson Introd. Nucl. Engin. vi. 249 The X-pile has no thermal shield... After 10 years operation there is no material damage of the concrete, which would indicate that the possibility of failure of concrete due to thermal stress may be much less severe than is generally assumed. Ibid., A thermal shield is an inner wall..which is placed between the reactor and the biological shield. Its function is to remove most of the heat energy of the gammas and thermal neutrons..and thereby protect the biological shield from damage. 1955Sci. Amer. July 58/1 Coal supplied only 34 per cent of the nation's total B.T.U.'s (British thermal units). 1957Times 12 Nov. (Canada Suppl.) p. iii/2 A 1,200,000 h.p. thermal power station is to be built near Vancouver, using natural gas. Ibid. 11 Dec. 16/4 It has been necessary to increase the capacity of the distillation unit and provide a thermal cracker. 1958C. C. Adams Space Flight 265 The MA-2 is a special suit that is ventilated for travel through the thermal barrier, and the MA-1 is a new ARDC helmet. 1960Chalmers & Quarrell Physical Examination of Metals (ed. 2) iii. 183 The simplest method of carrying out a thermal analysis is to place the specimen in a furnace which is arranged to have a negligible temperature gradient over a zone somewhat greater than the length of the specimen. 1961Guardian 12 June 6/6 A domestic thermal storage heater is now available. 1962Research XV. 80/1 Uranium polycarbide..is much more resistant to thermal shock and thermal cycling. 1962Simpson & Richards Physical Princ. Junction Transistors ix. 210 In extreme cases this positive feedback may lead to a catastrophic increase in temperature—a phenomenon commonly called ‘thermal runaway’. 1962Newnes Conc. Encycl. Nucl. Energy 357/2 The separations achieved in a convection⁓free system are small, and are only used to determine the magnitude of the thermal diffusion effect and to provide information on intermolecular force fields. 1963B. Fozard Instrumentation Nucl. Reactors xiii. 166 A count rate from the fission chamber of 105 c/s..is produced by a neutron flux, in the thermal column, of about 5 × 106 neutrons cm—2 sec—1. Ibid. 170 Thus the reactor can be operated under virtually isothermal conditions over a wide range of load, with consequent constancy of steam conditions and absence of thermal cycling. 1964H. S. Hvistendahl Engin. Units vii. 110 The legal definition of the Btu is the amount of heat required to raise 1lb of water from 60 to 61°F at standard atmospheric pressure. 1965R. G. Kazmann Mod. Hydrol. iv. 109 The so⁓called thermal pollution of streams has resulted primarily from the installation of steam-electric generating plants along our rivers. 1966C. R. Tottle Sci. Engin. Materials v. 117 The mean free path l depends on the thermal agitation of the lattice. Ibid., In less regular lattices, such as those of amorphous materials, there is a reduced probability of attenuation of the thermal wave, by virtue of the variable distances between the atoms. 1968R. R. Ernst in Lawrence & Block Disinfection, Sterilization & Preservation vii. xliii. 707/2 The thermal death point is the lowest temperature at which a suspension of bacteria is killed in 10 minutes. This standard has been almost abandoned. 1969Thermal pollution [see pollution 1 a]. 1970Nature 19 Sept. 1182/1 The technique of thermal imaging—picking up infrared radiation from the human body and displaying the resulting thermal image on an oscilloscope—..has been used to map the flow of warm arterial blood into, for example, tumours and varicose veins. 1971Gloss. Soil Sci. Terms (Soil Sci. Soc. Amer.) 21/1 Thermal analysis (differential thermal analysis), a method of analyzing a soil sample for constituents, based on a differential rate of heating of the unknown and standard samples when a uniform source of heat is applied. 1972Sci. Amer. July 33/3 This combination of conditions is all that is needed to produce the X rays, since accelerated charges are a source of electromagnetic radiation. A compact name for the process is ‘thermal bremsstrahlung’. 1972Oxf. Univ. Gaz. CII. Suppl. No. 8. 3 Work has begun on the installation of a second thermal storage boiler. 1973‘K. Royce’ Spider Underground viii. 119 Someone must be on tap to answer awkward questions if Old Bill [sc. the police] arrives. The thermal lance men will be below. 1973J. G. Tweeddale Materials Technol. I. iv. 95 Thermal diffusivity (a) is important when it is necessary to consider the effects of temperature differences set up in a material during transfer of heat. Ibid., Both thermal conductivity and diffusivity cease to have much meaning for the liquid state since in that state the principal mechanism of transfer becomes convective mixing. 1974Sci. Amer. Dec. 95/2 They are not die-cast in significant quantity now because the thermal shock to the metal components, including the mold, is so severe that the life of the components is short. 1975McGraw-Hill Yearbk. Sci. & Technol. 44/2 Some kind of thermal shield had to be designed, fabricated, and deployed quickly if Skylab was to be saved. 1975G. J. King Audio Handbk. iv. 106 Since f.e.t.s are less temperature sensitive than bipolar transistors, temperature compensation is not necessary, neither can thermal runaway occur, for Io tends to fall with increasing temperature. 1975D. G. Fink Electronics Engineers' Handbk. xxii. 60 Thermal noise for the most part originates in the first stages of the radio receiver and sets the minimum signal amplitude acceptable for a given signal-to-noise ratio. 1977F. Webb Go for Out vii. 125 A modern peterman needs explosives—else thermal lances. 1977I. M. Campbell Energy & Atmosphere v. 86 There is unlikely to be a thermal pollution problem of any importance on a global basis within the forseeable future. 1978Jrnl. R. Soc. Arts CXXVI. 683/1 Structures of supersonic aircraft are subject to thermal stresses due to temperature gradients. 1980Times 4 Aug. 17/2 Thermal imaging..involves the visualization of objects and scenes by detecting and processing the infra-red energy they emit. 1982Daily Tel. 20 Aug. 5/2 Their passive infra-red viewers, image intensifiers, and thermal imagers were excellent. 1982Sci. Amer. Dec. 93/1 Thermal printers, which cost less than $500, burn an image into a special paper at a rate of some 50 characters per second.
b. Nucl. Physics. thermal neutron, a neutron which is in thermal equilibrium with its environment (see quot. 1966); so thermal speed, thermal velocity, the speed characteristic of such a neutron; thermal reactor, a nuclear reactor in which the fission process relies upon thermal neutrons. Cf. slow neutron, slow reactor s.v. slow a. 13 c.
1936Physical Rev. XLIX. 520/1 It is therefore not necessary to ascribe all large cross sections to neutrons of thermal velocities. 1938Ibid. LIV. 235/1 (heading) Collimated, variable energy beam of pure thermal neutrons. 1945H. D. Smyth Gen. Acct. Devel. Atomic Energy Mil. Purposes viii. 79 We now introduce a factor f, called the thermal utilization factor, which is defined as the probability that a given thermal neutron will be absorbed in the uranium. 1949H. Etherington in S. C. Rothmann Constructive Uses of Atomic Energy v. 76 In a thermal reactor fission is produced by neutrons that have been slowed approximately to thermal velocities. 1959Listener 19 Nov. 872/1 At slow or ‘thermal’ speeds neutron capture by nuclei of Uranium 238 is less important. 1966C. R. Tottle Sci. Engin. Materials x. 236 Fast neutrons may be moving at speeds of the order of 1010 cm sec—1 with an energy of 1 to 10 MeV. When slowed down to a similar order of energy to that of the thermal vibration of atoms (hence called thermal neutrons) the speed is about 105 cm sec—1 at an energy of 1 eV. 1971Nature 23 July 211/1 The companies say that they have between them a good deal of experience in building thermal reactors of several types.
c. Promoting the retention of heat. Usu. of clothes, esp. underwear. thermal pane = Thermopane s.v. thermo-.
1970Toronto Daily Star 24 Sept. 16/2 (Advt.), Quilted thermal suits. 1973Times 9 Aug. 5/6 He has thermal underwear for use at high altitudes. 1974H. MacInnes Climb to Lost World viii. 122, I had taken the precaution of carrying my pair of calf-length thermal boots with me... They proved very useful in this swampy ground. 1978Detroit Free Press 16 Apr. e 5/1 In addition to long johns, thermal socks and two caps, Harwell wore a tee shirt. 1978T. Gifford Glendower Legacy 39 He..glanced out the wide thermal-pane window. 1982Oxford Star 4–5 Feb. 10/7 Tartan Cottage, Oxfordshire's crashed mail order clothing firm, has been rescued by a thermal underwear company.
3. fig. Heated with passion; erotic, passionate, impassioned.
1866Lond. Rev. 18 Aug. 178 Instead of the establishment in England of a thermal school of poetry; instead of the revivification of a grand (and wicked) old Paganism.
Hence therˈmality, thermal condition; ˈthermally adv., in a thermal manner; by means of or with regard to heat.
1884tr. L. Brachet's Aix-les-bains i. 74 We must pay special attention to the thermality, which is the sole bond of union [etc.]. 1871Tyndall Fragm. Sc. (1879) I. xvii. 449 The experiments proved rock-salt to be coloured thermally.
▪ II. thermal, n.|ˈθɜːməl|
[f. prec. adj.]
A rising current of relatively warm air, used by gliders and birds to gain height.
1933Jrnl. R. Aeronaut. Soc. XXXVII. 678 Herr Hirth had gained a great deal of experience regarding ‘thermals’, that is to say, ascending currents of warm air which can be used for soaring as distinct from soaring in the currents beneath clouds. 1950‘N. Shute’ Town like Alice 229 She rolled over on her back and watched a seagull soaring in the thermals from the island. 1962Amer. Scientist L. 180 Thermal soaring is the method most commonly used by soaring birds. 1974‘G. Black’ Golden Cockatrice iii. 60 He had been using that moving water belt beyond the harbour as a bird uses a thermal.
Hence ˈthermalling vbl. n., soaring in thermals.
1936Archit. Rev. LXXIX. 255/3 For greater heights the second and more interesting method is employed; what is known as ‘thermalling.’ This is the utilization of the columns of rising air that are always in existence under certain weather conditions. 1974Reader's Digest Feb. 89 With a Rogallo you can also do another type of soaring, called thermaling, where you circle in chimney-like updrafts of warm air that rise from sun-heated ground.
Add:2. pl. Short for ‘thermal underwear’ (see thermal a. 2 c).
1979Consumers' Research Mag. Dec. 28/2 Sears..illustrates four grades of thermals characterized as ‘For cool weather’, ‘For cold weather’, ‘For very cold weather’, and ‘For coldest weather’. 1981Good Housekeeping (N.Y.) Oct. 232 Look for easy-care thermals..if you'll be wearing the underwear frequently. Some thermals require hand laundering. 1986Here's Health Dec. 91/2 If, like me, you take a perverse pleasure in standing at the edge of a lake or river with the wind whistling over your binoculars and through your thermals, you must be a true birdwatcher. 1990Country Walking Jan. 87 (heading) Our testers have been out walking in a couple of upmarket jackets and some warm thermals. |