n. 熵

[计] 熵

[化] 熵

[医] 熵(热力学上的函数)

Entropy \En"tro*py\, n. [Gr. ? a turning in; ? in + ? a turn,
fr. ? to turn.] (Thermodynamics)
A certain property of a body, expressed as a measurable
quantity, such that when there is no communication of heat
the quantity remains constant, but when heat enters or leaves
the body the quantity increases or diminishes. If a small
amount, h, of heat enters the body when its temperature is t
in the thermodynamic scale the entropy of the body is
increased by h / t. The entropy is regarded as measured from
some standard temperature and pressure. Sometimes called the
{thermodynamic function}.

The entropy of the universe tends towards a maximum.
--Clausius.

Heat \Heat\ (h[=e]t), n. [OE. hete, h[ae]te, AS. h[=ae]tu,
h[=ae]to, fr. h[=a]t hot; akin to OHG. heizi heat, Dan. hede,
Sw. hetta. See {Hot}.]
1. A force in nature which is recognized in various effects,
but especially in the phenomena of fusion and evaporation,
and which, as manifested in fire, the sun's rays,
mechanical action, chemical combination, etc., becomes
directly known to us through the sense of feeling. In its
nature heat is a mode of motion, being in general a form
of molecular disturbance or vibration. It was formerly
supposed to be a subtile, imponderable fluid, to which was
given the name {caloric}.

Note: As affecting the human body, heat produces different
sensations, which are called by different names, as
heat or sensible heat, warmth, cold, etc., according to
its degree or amount relatively to the normal
temperature of the body.

2. The sensation caused by the force or influence of heat
when excessive, or above that which is normal to the human
body; the bodily feeling experienced on exposure to fire,
the sun's rays, etc.; the reverse of {cold}.

3. High temperature, as distinguished from low temperature,
or cold; as, the heat of summer and the cold of winter;
heat of the skin or body in fever, etc.

Else how had the world . . .
Avoided pinching cold and scorching heat! --Milton.

4. Indication of high temperature; appearance, condition, or
color of a body, as indicating its temperature; redness;
high color; flush; degree of temperature to which
something is heated, as indicated by appearance,
condition, or otherwise.

It has raised . . . heats in their faces. --Addison.

The heats smiths take of their iron are a blood-red
heat, a white-flame heat, and a sparkling or welding
heat. --Moxon.

5. A single complete operation of heating, as at a forge or
in a furnace; as, to make a horseshoe in a certain number
of heats.

6. A violent action unintermitted; a single effort; a single
course in a race that consists of two or more courses; as,
he won two heats out of three.

Many causes . . . for refreshment betwixt the heats.
--Dryden.

[He] struck off at one heat the matchless tale of
``Tam o' Shanter.'' --J. C.
Shairp.

7. Utmost violence; rage; vehemence; as, the heat of battle
or party. ``The heat of their division.'' --Shak.

8. Agitation of mind; inflammation or excitement;
exasperation. ``The heat and hurry of his rage.'' --South.

9. Animation, as in discourse; ardor; fervency; as, in the
heat of argument.

With all the strength and heat of eloquence.
--Addison.

10. (Zo["o]l.) Sexual excitement in animals; readiness for
sexual activity; estrus or rut.
[1913 Webster +PJC]

11. Fermentation.

12. Strong psychological pressure, as in a police
investigation; as, when they turned up the heat, he took
it on the lam. [slang]
[PJC]

{Animal heat}, {Blood heat}, {Capacity for heat}, etc. See
under {Animal}, {Blood}, etc.

{Atomic heat} (Chem.), the product obtained by multiplying
the atomic weight of any element by its specific heat. The
atomic heat of all solid elements is nearly a constant,
the mean value being 6.4.

{Dynamical theory of heat}, that theory of heat which assumes
it to be, not a peculiar kind of matter, but a peculiar
motion of the ultimate particles of matter.

{Heat engine}, any apparatus by which a heated substance, as
a heated fluid, is made to perform work by giving motion
to mechanism, as a hot-air engine, or a steam engine.

{Heat producers}. (Physiol.) See under {Food}.

{Heat rays}, a term formerly applied to the rays near the red
end of the spectrum, whether within or beyond the visible
spectrum.

{Heat weight} (Mech.), the product of any quantity of heat by
the mechanical equivalent of heat divided by the absolute
temperature; -- called also {thermodynamic function}, and
{entropy}.

{Mechanical equivalent of heat}. See under {Equivalent}.

{Specific heat of a substance (at any temperature)}, the
number of units of heat required to raise the temperature
of a unit mass of the substance at that temperature one
degree.

{Unit of heat}, the quantity of heat required to raise, by
one degree, the temperature of a unit mass of water,
initially at a certain standard temperature. The
temperature usually employed is that of 0[deg] Centigrade,
or 32[deg] Fahrenheit.