Abstract: A flow meter (10) employs phased arrays (14a, 14b, 16a, 16b, 18a, 18b, 20a, and 20b) of ultrasonic transducers mounted on the exterior of a pipe (12) to transmit and receive sound directed through paths that pass through the pipe interior. The flow meter (10) determines the rate of fluid flow through the pipe (12) by comparing the sound-propagation times for sound traveling the same paths in opposite directions. By driving the transducers as phased arrays, the flow meter (10) can employ sound-propagation paths that form angles to the normal to the interior pipe wall that exceed those dictated by Snell's law as applied to the relative propagation speeds in the pipe wall and the fluid.

Abstract: A hydrophone (16) having a short-baseline array of transducers (12A, 12B, and 12C) as well as a long-baseline array of transducers (14A, 14B, and 14C) includes switches 30A, 30B, and 30C) for selectively connecting the outputs of the arrays to a cable (18) that carries the signals to processing circuitry (20) aboard an ocean-going vessel (24). The switches (30A, 30B and 30C) change state in accordance with the output of a narrow-band filter (42), which indicates whether the received signal is of a predetermined frequency and thus is likely to have been produced by an intended source. Due to the delay inherent in the narrow-band filter 42, the processing circuitry (20) thus processes the response of the long-baseline array to the first part of a beacon pulse and the response of the short-baseline array to the second part of the beacon pulse.

Abstract: A novel acoustic flow-measuring apparatus and method of the type comprising a plurality of pairs of transducers mounted at the walls of a pipe carrying the fluid to be measured. Each pair is formed of opposed upstream and downstream transducers which project and receive acoustic energy toward each other along an intermediate acoustic path. Circuit means are provided whereby a general velocity distribution function is particularized by a relatively simple signal processing system utilizing a curve-fitting procedure.

Abstract: Significant decreases in bronchial sensitivity to cat dander in patients who experience asthmatic symptoms on exposure to cats are achieved by subjecting the patient to immunotherapy employing various dilutions of a cat dander extract containing at least 10% (based on total solids content) cat allergen 1 and, when undiluted, at least 300 micrograms/ml cat allergen 1. Cat allergen 1 is an antigen having a molecular weight between 30,000 and 60,000 daltons. It is identifiable by its ability to form a precipitin line with allergen 1 antiserum. A double blind, rigorously controlled study of the immunotherapy process has demonstrated that significant reductions in bronchial sensitivity may be routinely obtained in asthmatics of this class.