acid treatment: A refining process in which unfinished petroleum products, such as gasoline, kerosine, and diesel oil, are contacted with sulfuric acid to improve their color, odor, and other properties.
acid-water pollution: Industrial wastewaters that are acidic, usually appears in effluent from the manufacture of chemicals, batteries, artificial and natural fiber, fermentation processes (beer), and mining.
aciding: A light etching of a building surface of cast stone.
Ackerman linkage: NULL
acme screw thread: A standard thread having a profile angle of 29° and a flat crest, used on power screws in such devices as automobile jacks, presses, and lead screws on lathes. Also known as acme thread.
acme thread: NULL
acoubuoy: An acoustic listening device similar to a sonobuoy, used on land to form an electronic fence that will pick up sounds of enemy movements and transmit them to orbiting aircraft or land stations.
acoustic array: A sound-transmitting or sound-receiving system whose elements are arranged to give desired directional characteristics.
acoustic center: The center of the spherical sound waves radiating outward from an acoustic transducer.
acoustic clarifier: System of cones loosely attached to the baffle of a loudspeaker and designed to vibrate and absorb energy during sudden loud sounds to suppress these sounds.
acoustic coupler: A device used between the modem of a computer terminal and a standard telephone line to permit transmission of digital data in either direction without making direct connections.
acoustic delay: A delay which is deliberately introduced in sound reproduction by having the sound travel a certain distance along a pipe before conversion into electric signals.
acoustic detection: Determination of the profile of a geologic formation, an ocean layer, or some object in the ocean by measuring the reflection of sound waves off the object.
acoustic fatigue: The tendency of a material, such as a metal, to lose strength after acoustic stress.
acoustic feedback: The reverberation of sound waves from a loudspeaker to a preceding part of an audio system, such as to the microphone, in such a manner as to reinforce, and distort, the original input. Also known as acoustic regeneration.