sections, and shear-velocity reflectivity sections, for reflection points in giv- en geologic formations. The CDP gather is conducted at angles of offset of less than 20-30 deg. Assumptions can then be made which allow the appli- cations of linear fitting techniques to the gathered clata.•SAC

4,537,256

43.40.Ph SONIC FRACING PROCESS AND MEANS TO CARRY OUT SAID PROCESS

Franklin Beard, Houston, TX 27 August 1985 (Class 1661299); filed 13 June 1983

Enhancement of oil and gas production in wells is usually accom- plished by producing cracks and fissures in the surrounding formation. This patent describes a means and method for producing a series of explosions with both time spacing and amplitude controlled to cause fine formation

wave to be measured, and radiates a return from the point C back to the transducer via the point D. The length of the surface wave path B-C is determined, in part, by the focal distance of the lens and its height above the solid. Presumably, there is only one set of off-axis rays which will be at the proper angle to excite the surface wave and radiate back, but there is no discussion on this point. The discussion cites the need for a coupling liquid and compares measurements with reported values on steel, glass, si, and sapphire. They claim accuracies to within 2%.--/WD

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fissures without grossly distorting the fortnation. No estimate of the re- quired explosion size is given, but the description and drawing leads one to think that they are comparable to that produced in the cylinders of a small automobile engine.4AC

4,524,621

43.60.Qv, 43.85.DJ METHOD FOR MEASUREMENT OF VELOCITY OF SURFACE ACOUSTIC WAVE

Kazushi Yanmnsk• assignor to the Agency of Industrial Science snd Technology; Ministry of International Trade snd Industry

25 June 198S (Class 73/597); filed 6 September 1983

The method is designed to measure the velocity of a leaky surface wave on a solid-liquid interface. The measurement relates to the physical proper- ties of the solid (e.g., hardness or defects). A short acoustic pulse is generat- ed by transducer 2 and the arrival times of three returns are compared to calculate the surface wave velocity. The three returns are as follows: a direct reflection from the lens surface at E; the specular reflection from the solid's surface at F; and a return from a path comprised of the off-axis ray which leaves the lens at A, strikes the solid at B, travels on the solid as the surface

4,523,469

43.60.Sx LASER GENERATION OF ULTRASONIC WAVEFORM RECONSTRUCTIONS

Wi!!i•,n R. Scott and Charles S. lb, as•i•tors to the United States of America

18 June 1985 (Class 73/603); filed 19 January 1983

Apparatus is described for controlling the beam pattern of laser-gener- ated ultrasonic waves through the projection of holographic waveform im- ages. Two pulsed lasers provide pulses of laser light through respective wave front image transparencies. The two light beams separated in time are brought into spacial convergence and with spacially coincident focus upon the surface of a sample of material to be tested. Thermal elastic waves pro- duced by laser heating at the sample surface transform into a desired acous- tic beam pattern determined by the nature of the wave fronts which the hologram transparency represents. The position of the coincident image on the sample may be moved by varying the time between the two pulses.--

4,531,410

43.60.Sx METHOD OF AND APPARATUS FOR

DETECTING FLAWS INSIDE ARTICLES, MORE PARTICULARLY STRUCTURAL COMPONENTS, BY MEANS OF ACOUSTIC HOLOGRAPHY

Horst-Artur Crostack, Federal Republic of Germany 30 July 1985 (Class 73/603); filed in Germany 10 May 1982

Acoustic holography is used for the characterization of flaws in materi- als under various mechanical loading conditions, and also in thin materials and in those which scatter sound. In the method, a load is applied to the flaw area under investigation, and this area is subjected to ultrasonic pulses at least at two different times, each corresponding to an extreme value of the loading. The ultrasonic pulses are short with respect to the load period. After reaction of the pulses with the flaw, reference pulses are superimposed on the ultrasonic pulses, whereupon the hologr• m, of these ultrasonic ap- plications are superimposed to give an interferogram which can be evaluat-

4,286,116

43.72. - p DEVICE FOR THE PROCESSING OF VOICE SIGNALS

Jean-Claude B. Sadou, ussi•nor to Thomson-CSF 25 August 1981 (Class 179/1 P); filed in France 29 September 1978

•nat is patented here is simply the concept that a detector for the presence or absence of a speech signal requires a firrite amount of time to

590 d. ̂ coust. Soc. Am. 79(2), Feb. 1986; 0001-4966/86/02590-02500.80; ¸ 1986 ^coust. Soc. Am.; Patent Reviews 590

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