Abstract: An ultrasonic system for determining the quality of concrete under water hout inaccuracies caused by electromagnetic interference from the ultrasonic generator. An ultrasonic generator applies pulses to the concrete. An ultrasonic detector detects the ultrasonic pulses and produces corresponding signals that are indicative of ultrasonic pulses that have passed through the material. Signal processing circuitry processes the signals to determine the transit time of the ultrasonic pulses through the material. The signal processing circuitry is disabled for a predetermined time after application of each ultrasonic pulse to the material to prevent noise produced by the means for applying ultrasonic pulses to the material from entering the signal processing circuitry and causing spurious measurements.

Abstract: A measuring apparatus which detects defects in underwater concrete structs by measuring the compressive strength of the structure. The measuring apparatus comprises a rebound hammer which has extending from the nose thereof a plunger. The plunger is pressed against the structure whose compressive strength is being measured forcing the plunger into the rebound hammer's housing which releases a spring driven mass. A resistive film strip which is in electrical contact with the mass detects the maximum rebound of the mass and provides an electrical signal indicative of this maximum rebound. A data acquisition and processing circuit comprising a microprocessor and signal conditioning electronics receives, processes and stores the electrical signals provided by the resistive strip. This circuit includes a peak detection circuit which captures the peak output signal from the resistive strip.

Abstract: An apparatus for reducing sedimentation in ship berths including one or m modules, spanning the entrance of a ship berth and providing a continuous, homogeneous, impervious barrier, each module including a base located on the sea floor, an accordion type curtain extendable in the vertical direction and attached on its bottom side to the base, a float attached to the curtain on the top side, a primary operating system for raising and lowering the curtain and a secondary operating system for raising the entire apparatus to the sea surface for repair or removal.