frequency standard produces an accurate
81Electronic keyboard — An electronic keyboard. An electronic keyboard (also called digital keyboard, portable keyboard and home keyboard) is an electronic or digital keyboard instrument. The major components of a typical modern electronic keyboard are: Musical keyboard …
82sedimentary rock — Rock formed at or near the Earth s surface by the accumulation and lithification of fragments of preexisting rocks or by precipitation from solution at normal surface temperatures. Sedimentary rocks can be formed only where sediments are… …
83Pressure measurement — The construction of a bourdon tube gauge, construction elements are made of brass Many techniques have been developed for the measurement of pressure and vacuum. Instruments used to measure pressure are called pressure gauges or vacuum gauges. A… …
84Digital Audio Broadcasting — For other digital audio broadcasting systems, see Digital radio.   Countries with regular services …
85Dolby noise reduction system — Dolby NR is the name given to a series of noise reduction systems developed by Dolby Laboratories for use in analogue magnetic tape recording. The first was Dolby A professional noise reduction for recording studios in 1966, but the best known is …
86Timeline of luminiferous aether — The timeline of luminiferous aether begins in the late 19th century with the concept of luminiferous aether ( light bearing aether ), or ether, as a medium for electromagnetic propagation. The aether was assumed to exist for much of the 19th… …
87Glossary of fuel cell terms — The Glossary of fuel cell terms lists the definitions of many terms used within the fuel cell industry. The terms in this glossary may be used by fuel cell industry associations, in education material and fuel cell codes and standards to name but …
88gravitation — gravitational, adj. gravitationally, adv. /grav i tay sheuhn/, n. 1. Physics. a. the force of attraction between any two masses. Cf. law of gravitation. b. an act or process caused by this force. 2. a sinking or falling …
89pregnancy — /preg neuhn see/, n., pl. pregnancies. the state, condition, or quality of being pregnant. [1520 30; PREGN(ANT) + ANCY] * * * Process of human gestation that takes place in the female s body as a fetus develops, from fertilization to birth (see… …
90Numerical control — CNC redirects here. For other uses, see CNC (disambiguation). A CNC Turning Center …
