Rockwell International Corporation

Electric Power Research Institute Incorporated

Hazeltine Corporation

Other

Carmine F Vasile

Robert B Thompson

Christopher M Fortunko

George A Alers

William E Peterson

Teong C Lim

Umit Tarakci

Sheila F Vasile

Roger B Houston

A transistor circuit is provided with a symmetrical floating configuration for attaining multifunction operation of a transistor having symmetrical source and drain characteristics, preferably a GaAs MESFET. The circuit includes a balun which may be configured as a transformer, a differential amplifier, or a magic-tee waveguide depending on the frequency of signals to be processed by the circuit. Balanced terminals of the balun may be directly or capacitively coupled to source and drain terminals of the transistor. Tuning circuits are employed for applying signals having different frequencies to the transistor and for extracting intermodulation products generated by the transistor in response to the signals at the different frequencies. With the direct connection between the balun and the transistor, alternating voltages may be impressed between the terminals of the transistor to alternate source and drain regions of the transistor. Functions of amplification, modulation, bipolar attenuation, four-quadrant multiplication and correlation, power frequency tripling, and mixing are obtainable. The transistor may be replaced with a pair of transistors connected in series or in antiparallel connection.

Multifunction floating FET circuit

A system for recovery systems improving heat recovery from hot waste water is provided whereby cold feed water is preheated by means of extracting heat from hot waste water by passing said hot waste water and said cold feed water through a heat exchanger. Said preheated feed water is directed simultaneously to the hot water heater and to mixing valves at the point of usage of tepid water. Equal volumes of waste water and cold feed water flow through the system.

Equal volume, contraflow heat exchanger

A delay line circuit provides variable delay and phase shift to electric signals propagating along the delay circuit. The circuit is formed of a set of varactors constructed either as varactor chips or as a set of mesas upstanding from a gallium arsenide substrate. A ground plane interconnects bottom terminals of the varactor chips while a strip line conductor interconnects top terminals of the varactor chips. In the case of the mesa configuration, a metallized layer covers the regions between the mesas without contacting the base portions of the mesas. The strip line conductor makes contact with the respective mesas via a set of metallic posts upstanding from respective ones of the mesas. Dielectric material may be inserted between the strip line conductor and the metallic layer to position the strip line conductor relative to the metallic layer, which layer serves as a ground plane in a transmission line comprising the strip line conductor.

Automatically adjustable delay circuit having adjustable diode mesa

An electromagnetic transducer for exciting selected modes of ultrasonic vibration in a tubular body. The transducer includes a plurality of rows of permanent magnets of alternating polarity with a coil provided about the magnets whereby a current is conducted through the magnetic fields. The rows of magnets are provided in carriers which are yieldably biased towards the inner surface of a tubular body during inspection.

Electromagnetic acoustic transducer for tube inspection

Disclosed is a correlation receiver for processing an elctrical signal derived from an acoustic signal in a test object, including a signal generator for producing a reference waveform, a multiplier for combining the electrical signal and the reference waveform, an inegrator for integrating the combined signal, and a sample and hold circuit for detecting and holding the output of the integrator. In another embodiment, the signal generator also produces a second reference waveform in quadrature with the first reference waveform, and the receiver further inclues a second multiplier for combining the electrical signal and the second reference waveform, a second integrator for integrating the combined signal, and a means for combining the integrated first and second combined signals to produce an output indicating the structural integrity of the test object.

Signal processing technique for ultrasonic inspection

Disclosed is a method for determining the thickness of an object, including the steps of generating a higher order mode ultrasonic wave at a first location on the object, varying the frequency of the generated wave, and measuring, at a second location on the object, the minimum frequency at which the generated wave will propagate in the object. Where the ultrasonic wave generated is a horizontally polarized shear wave, the thickness t may be calculated from the relationship

Ultrasonic apparatus and method for measuring wall thickness

Disclosed is a method for evaluating the structural integrity of an object, including the steps of generating a lowest order horizontal shear wave in the object, detecting the wave after it has propagated through the object, time gating the detected signal to reject nonuseful portions, Fourier transforming the time response of the detected signal into a frequency dependent response, and predicting the structural integrity of the object from the characteristics of the frequency response.

Ultrasonic non-destructive evaluation technique for structures of

Disclosed is an electromagnetic acoustic transducer, including a source of magnetic flux for establishing a static magnetic field, an electrical conductor for conducting an alternating current in the static magnetic field, and an electrically conductive, nonmagnetic shield disposed between the source of magnetic flux and the conductor.

Shielded electromagnetic acoustic transducers

Disclosed is a nondestructive test device for detecting a flaw proximate to a welded seam in a pipe, including an electromagnetic acoustic transmitting transducer for generating a horizontally polarized shear wave in the wall of the pipe, a high frequency generator operatively connected to the transmitting transducer for energizing the transducer, an electromagnetic acoustic receiving transducer for responding to a horizontally polarized shear wave within the wall, an amplifier operatively connected to the receiving transducer for boosting the response signal of the transducer, and an indicating instrument for receiving and displaying the amplified response signal. In the test method disclosed, a horizontally polarized shear wave is generated in the wall, the pipe is monitored to detect a reflected horizontally polarized shear wave, and a time-dependent representation of the amplitude of the reflected wave is displayed. The wave generating, monitoring, and displaying steps are repeated along a length of the pipe to provide a comprehesive flaw inspection of that length of the pipe. The times of arrival of the generated and reflected waves are correlated to determine the circumferential position of the flaw.

Nondestructive testing utilizing horizontally polarized shear waves

Disclosed is a method for evaluating a discontinuity in an object. As used to measure the depth of a surface discontinuity in a plate type of object, the method includes the steps of generating a horizontally polarized shear wave in the object directed substantially along the axis of the discontinuity, passing the generated wave through an aperture to diffract the wave prior to its arrival at the discontinuity, detecting the wave after it has propagated through the discontinuity, and calculating the depth of the discontinuity by correlating the phase and amplitude of the detected wave to the phase and amplitude of a similar wave propagated in a region of the object which is free of discontinuities.

Ultrasonic nondestructive testing method

Disclosed is a method for generating an ultrasonic wave in a material, utilizing a transducer adapted to induce a higher than fundamental mode wave in the material and a signal generator adapted to drive the transducer at a frequency above the cutoff frequency below which the higher mode wave will not propagate. For a horizontal shear wave, optimal transducer efficiency is obtained by selecting a driven frequency between a minimum cutoff frequency f.sub.c =v.sub.s n/2t and an upper frequency sufficiently close to f.sub.c to drive the transducer with at least a preselected increase in efficiency.

Method and apparatus for efficiently generating elastic waves with a

An electromagnetic transducer is provided which transmits and receives ultrasonic waves from a metallic part predominately in only one direction. At least two rows of permanent magnets are placed adjacent each other in a side-by-side relation. The N-S axes of the magnets are substantially parallel and adjacent magnets in each row have opposite polarity so that two periodic magnetic fields are created. The adjacent magnets are off-set by one-fourth period. Coils wrapped around each row of magnets are driven in phase quadrature in order to generate a unidirectional elastic wave in the metallic part. In another embodiment, sets of three rows of magnets are offset by one-sixth period and driven in 60.degree. phase shift.

Periodic magnet unidirectional transducer

Disclosed is an electromagnetic acoustic transducer for generating and detecting an elliptically polarized ultrasonic wave in an electrically conductive material. The transducer includes a row of uniformly sized, adjacent, alternately oriented permanent magnets, which establish a periodic magnetic field. Coaxially wound around the row is a first coil for inducing an alternating current perpendicular to the field and perpendicular to the periodic direction, while a second coil is wound around the coil orthogonal to the first coil to induce an alternating current perpendicular to the field and parallel to the periodic direction. An ultrasonic ellipsometer includes such a dual coil transmitting transducer for generating an elliptically polarized wave and a dual coil receiving transducer for detecting the wave after it has propagated through an electrically conductive medium. By using the ellipsometer to generate an elliptically polarized wave in a material and detect the change in polarization of the wave after propagating through the material, the apparatus can be employed to examine surface properties of the material.

Ultrasonic ellipsometer

A magnet is used to create a static magnetic field adjacent to the surface of a conductive material. At least one conductor runs through the magnetic field. When a pulse of current flows through the conductor, an elastic wave is generated in the material. In a preferred embodiment, a row of individual permanent magnets is used to create a periodic magnetic field. One side of a coil is placed in the periodic magnetic field so that a sheet of current moves transverse to the magnetic field when a pulse of current flows through the coil. When the coil is oriented parallel to the row of magnets, a horizontal shear wave is generated in the material. When the coil is oriented transverse to the row of magnets, a Lamb wave is generated in the material.

Electromagnetic transducer

At least one of several transducers on a piezoelectric substrate is externally short-circuited by a series resonance circuit for suppression of triple transit echoes. The resonance circuit is additionally connected to an amplifier via a high input or output impedance. In multi-transducer systems any two transducers are prevented from communicating via echo signals by such resonance circuits. In filter cascades several resonance circuits may be included in the interstage coupling circuit or between the input and output amplifiers on the one hand and the cascade on the other hand.

Growing community of inventors

Thousand Oaks, CA, United States of America

Carmine F Vasile