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Eng ID Term Definition
5781
underwater sound projector
A TRANSDUCER used to produ­ce SOUND in water. The conver­sion from electrical energy to SOUND is achieved through the use of either the pi... more
A TRANSDUCER used to produ­ce SOUND in water. The conver­sion from electrical energy to SOUND is achieved through the use of either the piezoelectric or mag­netostrictive effect. See MAGNETOSTRICTION and PIEZOE­LECTRICITY.
5782
underway (or under way)
(adv.). Without MOORINGS; not secured in any way to the ground or a WHARF. In motion, particularly the start of such motion after a standsti... more
(adv.). Without MOORINGS; not secured in any way to the ground or a WHARF. In motion, particularly the start of such motion after a standstill.
5783
undulating
(adj.). Having the form of WAVES or SWELLS, as undulating LAND.
5784
undulation
A continuously propagated motion to and from, in any fluid or elastic medium, with no permanent translation of the particles themselves.
5785
undulation of the geoid
The distance between the mathe­matical REFERENCE SPHEROID and the GEOID.
5786
unidirectional antenna
See ANTENNA.
5787
unifilar magnetometer
See MAGNETOMETER.
5788
uniform flow
Any CURRENT in which neither CONVERGENCE nor DIVERGENCE is present.
5789
unit magnetic pole
In magnetic theory, a fictitious entity analogous to a unit electric charge in electro­s­tatic theory.
5790
United Nations (UN)
The major international organiza­tion established to maintain international peace and security, to develop friendly relations among nations... more
The major international organiza­tion established to maintain international peace and security, to develop friendly relations among nations, to achieve cooperation in solving international pro­blems.
5791
United Nations Conference on Trade and Development (UNCTAD)
Helps to restructure patterns of international trade in order to enable developing countries to play their part in world commerce.
5792
United Nations Development Programme (UNDP)
An UN agency which registers organizations and institutions located in developing countries which have the capaci­ty for cooperative techni... more
An UN agency which registers organizations and institutions located in developing countries which have the capaci­ty for cooperative technical activities with organiza­tions in other developing nations. The subject matter includes education and training courses, research and technological development activities, consulting and expert services, and scientific and technical informa­tion and used primarily by institutions and govern­ments in developing countries.
5793
United Nations Educational, Scientific, and Cultural Organization (UNESCO)
Organized in 1945 to promote collaboration among nations in education, science, and culture; UNESCO is the parent agency for the INTERGOVERN... more
Organized in 1945 to promote collaboration among nations in education, science, and culture; UNESCO is the parent agency for the INTERGOVERNMENTAL OCEANOGRAPHIC COMMISSION.
5794
universal drafting machine
See PROTRACTOR: PARALLEL MOTION.
5795
universal level
See LEVEL: SPIRIT.
5796
Universal Time (UT)
TIME as defined by the rotational motion of the EARTH and determined from the apparent diurnal motions which reflect this ROTATION. Because ... more
TIME as defined by the rotational motion of the EARTH and determined from the apparent diurnal motions which reflect this ROTATION. Because of variations in the rate of rotation, Universal Time is not rigorously uniform. Also called Greenwich mean time.
5797
Universal Time 0 (UT0)
The uncorrected TIME of the EARTH's ROTATION as measured by the TRANSIT of STARS across the observer's MERIDIAN. This ROTATION is refer­red... more
The uncorrected TIME of the EARTH's ROTATION as measured by the TRANSIT of STARS across the observer's MERIDIAN. This ROTATION is refer­red to a fiducial mark on the ECLIPTIC which approxima­tes the position of the MEAN SUN.
5798
Universal Time 1 (UT1)
UT0 corrected for polar moti­on.
5799
Universal Time 2 (UT2)
UT1 corrected for seasonal variations in the EARTH's ROTATION.
5800
Universal Time Coordinated (UTC)
The time scale that is available from most broadcast time signals. It differs from INTERNATIONAL ATOMIC TIME by an integral number of second... more
The time scale that is available from most broadcast time signals. It differs from INTERNATIONAL ATOMIC TIME by an integral number of seconds. UTC is maintained within 1 second of UT1 by the introduction of 1-second steps (leap seconds) when necessary, normally at the end of Decem­ber. DUT1, an approximation to the difference UT1 minus UTC, is transmitted in code on broadcast time sig­nals.