Abstract: A coherent signal generated at a precise frequency determined by an atomic clock is transmitted by a moveable object. A receiver station compares the frequency of the coherent signal received from the moving object with a second coherent signal generated at the same precise frequency by an atomic clock in the receiver to determine the radial component of the velocity of the moveable object relative to the receiver as a function of the doppler shift of the transmitted signal. Low cost, low power, miniature atomic clocks with an accuracy of 10.sup.-11 make possible accurate measurements of velocities of only centimeters per second. Such velocity measurement can be used to enhance radar tracking in air traffic control and collision avoidance systems.

Abstract: There is provided a hermetically sealed dry-coupled transducer apparatus and system adapted for improved measuring of liquid level in a pipe or vessel, or for other instrumentation applications. The transducer system is characterized by having a hermetic seal at the junction of an acoustic window 33' and an outer shell 31' (thereby hermetically sealing a forward aperture of the outer shell), and a thin, compliant, threaded cap 46 enclosing a rearward aperture of the outer shell. The cap provides means for repetitively assembling and disassembling the transducer module, if necessary, prior to welding. In addition, a push rod applies acoustic coupling force to a piezoelectric transducer element to effect dry coupling to a surface, while the compliant cap prevents significant force transmission to the shell. The system exhibits limited reverberation and, moreover, is suitable for use in high-temperature environments.

Abstract: An ultrasonic position sensing apparatus for detecting open, closed and intermediate positions of a valve element movably mounted in a valve housing includes an ultrasonic target fixedly attached to the valve and having an echo surface which provides a travel time difference for a returning echo, depending on the position of the valve element. An ultrasonic transducer coupled to an outer surface of the valve housing transmits an ultrasonic pulse towards the target thereby generating the echo by striking the target; a monitor means connected to the ultrasonic transducer correlates valve position to the travel time of the returning echo.

Abstract: A method and apparatus for monitoring the velocity of flow of a fluid, by: causing fluid to flow through a conduit section defining a monitoring region, the conduit section having an interior defining a flow path which is free of any physical obstruction that can significantly influence fluid flow in the monitoring region; propagating a beam of energy across the flow path in the monitoring region in a direction transverse to the flow path, the energy being selected such that the beam is modulated by turbulence occurring in the fluid; detecting the modulated beam at a single location in the monitoring region after the beam has traversed the flow path and generating a single electrical signal representative of the detected modulated beam; and processing the single electrical signal in a manner to provide an indication of the modulation of the beam produced by the turbulence in the fluid.

Abstract: A system and method for determining the condition of one or more parameters of a valve, e.g., particularly a check valve in a fluid carrying pipe, by monitoring fluid turbulence downstream of the valve. An ultrasonic transmitter-receiver transducer pair provides a signal modulated by the fluid turbulence, which signal is demodulated and processed to obtain a signature or other signal indicative of the valve condition. The processes signature signal may additionally be compared with a measure of flow rate determined just upstream from the valve. By operating the ultrasonic system at high frequency and using appropriate detecting circuitry, low frequency interference from mechanical shocks and vibrations is avoided, yielding a reliable detection of the flow turbulence caused by the valve.

Abstract: A system for providing a temperature compensated measurement indicative of the height of a fluid in a vessel includes an acoustic waveguide in fluid communication with the vessel. A reference target is positioned within the waveguide. Ultrasonic signals are produced in the fluid and a timer measures a first transit time representative of the time for the ultrasonic signals to travel to and from the target and a second transit time representative of the time for the ultrasonic signals to travel to and from the surface of a fluid in the waveguide. A circuit calculates the height of the fluid in the waveguide from the first and second transit times. Another circuit determines the density of the fluid in the waveguide from the first transit time and normalizes the calculated height of the fluid based on the density of the fluid such that the normalized height is indicative of the height of the fluid in the vessel.

Abstract: A pipe section through which a liquid passes includes a transmitting and receiving transducer diametrically opposed on the surface of the pipe and arranged to project acoustic energy through the interior of the pipe whereby the output signal from the receiving transducer changes in the presence of a liquid in the acoustic path between the transducers. V-shaped grooves or other surface modifications are made to the surface of the pipe circumferentially between the transducers so as to redirect wall-borne acoustic energy to a more axial direction thus preventing its reception at the receiving transducer.

Abstract: Disclosed is an apparatus for overcoming acoustic path angle limitations and transducer coupling problems when an ultrasonic flow measurement method is used to measure water velocity in annular regions such as the downcomer of a nuclear steam generator. In accordance with one embodiment, two axially spaced ultrasonic transducers are coupled perpendicularly to the outer surface of a shell and align respectively with two 45.degree. reflecting surfaces on a structure which is inserted into the downcomer during shutdown. The acoustic path between reflecting surfaces is essentially in line with the fluid flow as desired for best sensitivity and accuracy. Acoustic performance is optimized and transducer mounting is simplified by having the transducers perpendicular to the shell surface. Other embodiments are disclosed for measuring the average flow velocity by angling the acoustic path across the annular region of the downcomer.

Abstract: A flowmeter wherein measurements relating to fluid flowing in a pipe are obtained by transmitting a laser beam from a high power pulsed laser into the fluid through an optical window in the pipe. The beam in the fluid causes a rapid thermal expansion of the fluid which generates a pressure pulse which travels axially up and down the pipe. Continuously operating low power laser beams are projected into the fluid at points displaced from the source of the acoustic pulse and these beams are modulated when the acoustic pulse passes them. The modulation is detected to obtain first and second transit times, these transit times being utilized to compute the desired fluid flow parameters.

Abstract: In a steam generator an ultrasonic probe is used to measure the accumulation of sludge between the tubes. A ribbon-like probe carrier is fed into the vessel and deflected by a carriage placed in alignment with a lane of tubes at 90.degree., the probe head being advanced in the lane to measure vertically and sideways the distance to the surface of the sludge. The probe carrier consists of two steel tapes held face-to-face by a plastic tube which has been heat shrunk. The conductors for the transducers are contained in the space between concave tapes. An adaptor mounted at the end of the probe carrier is amovably connected to the probe head. Probe head, adaptor and probe carrier are sealed so that measurement can be conducted inside the steam generator supposedly filled with water.

Abstract: A flowmeter transducer assembly specially designed for high temperature operation includes only dry-coupled elements. A subassembly preassembled before installation on the pipe section consists of a piezoelectric element held between front and backing electrodes. The backing electrode is backed by a contact electrode while leaving a gap therebetween to prevent reflection of acoustic energy back to the rear of the transducer. The subassembly is introduced into a housing clamped directly on a flow section of a pipe, where the pipe wall is an acoustic wave transmitting or receiving window. In a different embodiment the pipe may serve as the front electrode in dry coupling.

Abstract: A thick layer of epoxy resin is used to bond together the piezoelectric member and a stainless steel cap to form an acoustic transducer having a broad frequency response, and specific assembling steps are taken to manufacture the transducer with good reproducibility of the characteristics.

Abstract: A thick layer of epoxy resin is used to bond together the piezoelectric member and a stainless steel cap to form an acoustic transducer having a broad frequency response, and specific assembling steps are taken to manufacture the transducer with good reproducibility of the characteristics.

Abstract: An electroacoustic ultrasonic transducer is described which is usable under high pressure and high temperature operating conditions, and is readily replaceable. A piezoelectric transducer element is disposed within a metallic housing and coupled to a metallic acoustic window which is exposed to the sensed acoustic medium, with very efficient acoustic coupling between the piezoelectric element, the acoustic window, and a damping block disposed behind the piezoelectric element.