between successive levels, the energy difference between which is comparable with the sonic energy input.
SOVI ET PHYSICS - ACOUSTICS Calculation of the relative m o t i o n of aerosol particles in a sound field Timoshenko, V. I. Vol 16, No 4 ( A p r i l - J u n e 1971) pp 4 8 5 488. An expression is obtained in the quasistationary approximation for the relative h y d r o d y n a m i c drift velocity of aerosol particles in the Stokes flow regime. The dependence of th'e relative particle velocities on the parameters of the sound field and parameters of the aerosol is analyzed. The convergence time of the particles due to relative h y d r o d y n a m i c drift is estimated.
MATER IALS EVALUATION Recording rapid ultrasonic inspection data on a relatively slow-speed recorder Mesina, J. M. Vol 29, No 4 (April 1 9 7 1 ) p p 8 1 - 8 7 . Recording systems have been adapted to two pulsed ultrasonic tests for electric weld pipe. F u n c t i o n s of the system are (1) to record pipe weld quality as measured by ultrasound, and (2) to m o n i t o r proper e q u i p m e n t operation. The four-channel ultrasonic inspection systems have been modified to permit accurate recording of high-speed defect information on a relatively slow recorder.
PATENTS Transducers Institut Francaise du Petrole des Carburants et Lubrifiants British Patent 1,218,672 (1971) Filed 16 May 1968 In a pressure transducer for detecting acoustic waves in water, one face of a flat circular piezoelectric crystal is secured to the centre of a flat circular part of a first electrode which also has a thicker cylindrical part enclosing a part of a cylindrical body, and a second electrode is secured to the opposite face of the piezoelectric crystal.
Transistor oscillating circuits Endress & Hauser G m b H & Co British Patent 1,218,387 (1971) Filed 25 March 1968 Ultrasonic delay line Jenaer Glaswerk Schott & Gen (CarlZeiss-Stiftung) British Patent 1,232,933 (1971) Filed 4 March 1969 Electromechanical delay lines Thomson-CSF British Patent 1,234,016 (1971) Filed 11 March 1970 A dispersive delay line uses acoustic surface waves. It comprises a piezoelectric substrate and input and o u t p u t transducers in the form of thin-film electrodes with interleaved teeth. Transducers Industrial Research Products Inc British Patent 1,234,218 (1971) Filed 28 Nov 1968. Ultrasonic inspection devices T. I. (Group Services) Ltd British Patent 1,234,233 (1971) Filed 29 Jan 1969 Devices allow the presence of flaws in the wall of a tube to be detected despite variations in wall thickness (as in finned tube). Sonar systems Smiths Industries Ltd British Patent 1,234,237 (1971) Filed 12 Dec 1969 This is a sensor apparatus provided with fewer reception channels than transducers. The transmit/receive direction is stabilised against roll, pitch and yaw of the supporting ship. Electromechanical delay lines International Standard Electric Corp British Patent 1,234,266 (1971) Filed 7 Nov 1968 The delay line consists of a metal alloy sheet of thickness not more than half the wavelength of the ultrasonic wave to be propagated between input and o u t p u t piezoelectric transducers. Ultrasonic couplings Erapa AG British Patent 1,232,128 (1971) Filed 26 Sept 1969 An ultrasonic transducer particularly for fusion welding of plastics tape has a sonotrode for coupling the two piezoelectric elements to a workpiece.
Transducers Technical Ceramics Ltd British Patent 1,217,912 (1971) Filed 2 Feb 1968
Piezoelectric transducers Kistler Instrumente AG British Patent 1,225,799 (1971) Filed 19 June 1968.
An elongate transducer element is damped by a body of flowable non-creeping grease formed of fluorocarbon or halofluorocarbon polymer.
Acoustic analysis of fluids/piezoelectric transducers Microtek I n s t r u m e n t s Corp British Patent 1,225,032 (1971) Filed 5 March 1968.
Filters: delay lines Philips Electronic & Associated Industries Ltd British Patent 1,218,319 (1971) Filed 8 Oct 1969~
Electro-acoustic transducers; magnifying sound Compagnie des Compteurs British Patent 1,225,098 (1971) Filed 27 Feb 1969.
Ultrasonic inspection devices Nippon Kokan KK British Patent 1,225,424 (1971) Filed 28 March 1968 A flaw inspection system has a block containing an artificial flaw coupled to the workpiece being inspected. Ultrasonic inspection devices; probes S. T. D. Services Ltd British Patent 1,226,091 (1971) Filed 28 Feb 1968 Carrier m e m b e r s are stainless steel tubes apertured at each end to receive a lead zirconate transducer wafer silvered on both sides. Ultrasonic inspection devices S. T. D. Services Ltd British Patens 1,226,092 (1971) Filed 29 Feb 1968 The ultrasonic flaw-inspection system is for tubes and other elongated workpieces. Ultrasonic inspection devices S. T. D. Services Ltd British Patent 1,226,092 (1971) Filed (1971) Filed 29 Feb 1968. Ultrasonic pulse-echo apparatus/probes Realisations Ultrasoniques British Patent 1,226,987 ( 1 9 7 l ) Filed 9 July 1968 The ultrasonic apparatus consists of a transducer probe in the form of a piezo-electric wafer sandwiched between a loaded plastics damping block and a plastics quarter-wave plate of ultrasound transmissive material, the plate having a curved free surface for focusing. The plate constitutes an impedance transformer. Acoustic m e a s u r e m e n t of temperature Centre National de Recherches Metallurgiques British Patent 1,227,064 ( 1971 ) Filed 4 Sept 1969 Longitudinal and transverse ultrasonic waves are used to determine the temperature of a material, such as a steel bloom at over 1000°C. Acoustic navigation General Instrument Corp British Patent 1,228,047 (1971) Filed 20 Nov 1968 The receiving array of transducers consists of cylindrical h y d r o p h o n e s made up of rings of electrostrictive ceramic material. The transmitted frequencies arc low (eg 12 kHz) to reach the sea bed in deep waters. Seismic exploration; subaqueous signalling Texas Instruments Inc British Patent 1,228,227 ( 1971 ) Filed 19 Nov 1968 A towed h y d r o p h o n e streamer consists of an elongated jacket containing h y d r o p h o n e s and a filling of solid polymeric material which gives the streamer neutral buoyancy. Ultrasonic inspection devices G. Pettinato British Patent 1,229,635 ( 1971 ) Filed 5 Dec 1968 An ultrasonic probe assembly scans a rotating wheel in a m e t h o d for inspecting wheels of railway vehicles in situ.