Abstract: The present invention relates to a method for detecting a thickness of a tree canopy based on an ultrasonic echo signal, and belongs to the technical field of agricultural machinery information sensing and detection. The present invention analyzes and discriminates a first effective peak and a last effective peak of the ultrasonic echo signal, obtains a first effective peak time and a last effective peak time, and calculates the thickness of the tree canopy according to a provided calculation formula, thus realizing the direct detection of the thickness of the tree canopy. This method has characteristics such as a high accuracy and a wide application range, and is applicable to the field of detection of the thickness of a tree canopy in industries such as agricultural machinery and forestry machinery.

Abstract: An ultrasonic sensor probe (100) and controller (109). The controller (109) is operationally configured to determine and display wet and dry status of each of a plurality of ultrasonic sensors (156) positioned in the barrel (123) of the probe (100). The controller (109) may change the status of a sensor (156) from wet to dry or dry to wet if certain conditions are met, such as the sensor (156) consistently indicates the new status over multiple readings or over a predetermined period of time. The controller (109) preferably includes a two-wire output capable of producing a stepped analog or digital signal that indicates the fluid level in a container in which the probe (100) is positioned.

Abstract: Ultrasonic wave sensing device includes a reading transistor, an ultrasonic wave transducer, and an input circuit. The reading transistor includes a first node, a second node, and a control node, wherein the first node receives a reference voltage, the second node couples with a reading node, and the control node couples with a first signal node. The ultrasonic wave transducer couples between the first signal node and a first input node, and receives a first control signal from the first input node. The input circuit couples between the first signal node and a second input node, and receives a second control signal from the second input node. The ultrasonic wave transducer generates an ultrasonic wave according to the first control signal and the second control signal, and outputs a sensing signal to the control node according to a reflected sound wave.

Abstract: A sensor apparatus is provided for measuring within a region of a conduit for guiding a flow. The apparatus includes a transducer arrangement disposed at least partially around an external surface of a wall of the conduit and having one or more driver elements for exciting in operation a helical acoustic wave propagation within the wall of the conduit for leaking acoustical energy from the helical acoustic wave propagation over an extensive area of the wall of the conduit for stimulating waves in chordal paths within the flow, wherein the waves in the choral paths within the flow re-enter the wall of the conduit to propagate further as a guided helical wave. The transducer arrangement includes one or more sensors for receiving a re-entered portion of the acoustic wave propagation along the paths within the flow which interacts with the flow and includes information characterizing properties of the flow.

Abstract: A proximity sensing function is implemented using a collection of core independent peripherals (CIPs) in a microcontroller without software overhead to the central processor during operation thereof. A pulse width modulation (PWM) peripheral generates a high frequency drive signal that is on for a short duration to an ultrasonic transmitting transducer. An ultrasonic receiving transducer receives reflected ultrasonic pulses during an integration time window. The received pulses are detected and integrated into a voltage value. The integrated voltage value is compared to a prior voltage value average, and if different, generates a proximity sense signal of an object. Direction, distance and speed of the object may also be determined from the voltage values.

Abstract: A system and method for generating simultaneous plural frequencies in seismic exploration is disclosed. The method includes configuring a seismic source to emit a seismic signal that includes multiple frequencies emitted substantially simultaneously. The method additionally includes identifying a plurality of frequencies to include in the seismic signal and determining an amplitude of the seismic signal. The method further includes obtaining a seismic dataset corresponding to the seismic signal emitted by the seismic source and creating a seismic image of a subsurface of a seismic survey area.

Abstract: The invention consists in a method of characterizing a part made of composite material (30), the method comprising a step of determining a characteristic of a longitudinal ultrasound wave (41) traveling along a path within the part (30), and being characterized in that the travel time of a longitudinal ultrasound wave (42) transmitted by the part (30) is measured (E4).

Abstract: A floating transducer drive configured to isolate relatively low voltage system electronics from a relatively high voltage transmit circuit in an ultrasound imaging system. A receive circuit is electrically connected to an isolated local ground. An isolation circuit is electrically connected between the receive circuit and a relatively low-voltage processing circuit. The isolation circuit is configured such that during a transmit event during which the relatively high voltage transmit circuit sends a relatively high voltage signal to a transducer, the isolated local ground is electrically connected to the transmit circuit, but when the transmit event is not occurring, the isolated local ground is electrically connected to a system ground.

Abstract: An implantable microphone is described for use in hearing prosthesis systems. A cylindrical microphone housing has opposing circular cylinder ends and an interior volume containing an incompressible housing liquid. At least one housing membrane is on one of the cylinder ends and is in contact with the housing liquid and moveable in response to an acoustic signal outside the housing. An acoustic-electric transducer is coupled to the housing membrane for converting movement of the housing membrane into a corresponding electrical microphone signal.

Abstract: A method for ultrasonic testing of an object, the method comprising ultrasonic scanning of a plurality of scan regions of the object; converting ultrasonic echoes of the ultrasonic scanning into a plurality of electrical signals; gating the electrical signals to provide gated signals; and wherein different gating times are used for the electrical signals.

Abstract: A method is provided for calibrating ultrasonic signals passed through a crimp formed with respect to a deformable body via an ultrasonically-equipped crimp tool (UECT). The UECT verifies a crimp quality using the ultrasonic signals. The method includes forming the crimp, transmitting a first signal, e.g., a pulse, to a first transducer of the UECT, and converting the first signal, using the first transducer, into a second signal which defines an ultrasonic pulse. This pulse is transmitted through the UECT into the crimp. A second transducer converts the second signal into a third signal, which may be further conditioned, and the ultrasonic signals are calibrated using the third signal or its conditioned variant. An apparatus for calibrating the ultrasonic signals includes a pulse module (PM) electrically connected to the first and second transducers, and an oscilloscope or display electrically connected to the PM for analyzing an electrical output signal therefrom.

Abstract: An exploration operation, in which the transmission/reception position, at which ultrasonic waves are transmitted and received, is changed by a specified pitch distance, is performed for each of a plurality of incident angles. A nonlinear image in which echo signals acquired from harmonic waves of reflected waves are presented is generated for each incident angle. Each nonlinear image is converted into a frame conversion image in accordance with the cross-sectional shape of an exploration-target area. A signal intensity threshold for removing echo signals resulting from an orientation defect is determined in advance. Frame conversion images formed by only echo signals 41a whose signal intensity is the signal intensity threshold or more are overlapped to generate a nonlinear exploration image 35. Exploration of a welded portion 23 stably provides a nonlinear exploration image 35 in which the shape of an interface 25 of the welded portion 23 is shown accurately and clearly.

Abstract: A fluid flow sensor uses pairs of acoustic transducers to generate quasi-helical acoustic beams reflected multiple times from an inside surface of a pipe. The transducers are arranged so that each two pairs generate counter-rotating beams. When fluid flowing in the pipe has both a rotary and an axial flow component the rotary component adds to the apparent flow rate measured in one rotational direction and subtracts from that measured in the other. Hence, a combination of transit time measurements along the two paths can be used to cancel out the effects of the rotary flow component and yield a measure of the rate of flow along the pipe axis. In some cases multiple probes are used to increase the amount of flowing fluid that is sampled.

Abstract: A probe type acoustic transit-time flow sensor has paired transducers arranged to generate quasi-helical acoustic beams making a plurality of reflective contacts with a pipe's interior wall. The transducers in each pair are spaced apart along the flow axis so that transit-time measurements can be used both to measure the internal diameter of the pipe and to determine a flow rate. These measurements are combined to yield a volumetric flow rate. Various numbers of pairs of transducers can be put on a single probe or on multiple probes and used to provide a more accurate representation of a flow profile and therefore a more accurate volumetric flow determination.

Abstract: An acoustic time-of-flight size measuring device is added to the sensing head of an insertion probe sensor which may be used for measuring the flow of fluid in a pipe. The size-measuring device defines an acoustic beam making a plurality of reflective contacts with the pipe's interior wall. A time-of-flight measurement of this path length provides an accurate measurement of the internal diameter of the pipe. The magnitude of the transit time signal can also be used as an indicator of both insertion depth and angular orientation of the probe with respect to the pipe axis. In addition, the arrangement allows one to sense acoustic path attenuation caused by factors such as the buildup of deposits.

Abstract: A process for positioning at least one defect in a billet being forged into an article is described. The size and location of the billet is first determined, using a non-destructive test such as ultrasonic inspection. The movement of the defect under selected forging conditions is then predicted, using a finite element analysis model. The billet can then be positioned and forged under conditions which cause the defect to move to a non-critical area of the article. In this manner, a billet which might otherwise be discarded or set aside can often be retained for a useful purpose. Related articles are also described.

Abstract: The invention relates to a transmitting system for the generation of ultrasonic waves for testing materials, comprising a controllable signal generator and an ultrasonic transducer, wherein the signal generator and the ultrasonic transducer are arranged in the immediate vicinity of one another, in order to provide a transmitting system for ultrasonic testing which has higher effectiveness and lower manufacturing costs than known transmitting systems.

Abstract: Arrangements and methods for determining a relative position of two objects with respect to one another are presented wherein a radiation source generates a characteristic radiation field and a receiver measures radiation quantities of the radiation. The receiver transmits signals that are dependent on the measured radiation quantities in the characteristic radiation field to the evaluation unit, which determines the relative position of the objects with respect to one another dependent on the signals received from the receiver. Due to a connection of the two objects of the arrangement with an elastic connection having a predetermined stiffness, the evaluation unit determines the force acting between the objects and/or the moment acting between the objects from a relative positional change of the two objects with respect to one another dependent on the stiffness of the connections.

Abstract: A method for monitoring and measuring the buildup of deposits on the inner surface of a pipeline containing flowing fluid comprises (a) transmitting a first acoustic signal into the pipeline through the pipeline wall, (b) receiving echoes of the transmitted signal, and (c) determining from the received echoes how far from the pipeline inner surface the interface between the deposits and the flowing fluid lies. An alternative method for monitoring and measuring the buildup of deposits on the inner surface of a pipeline containing flowing fluid comprises (a) transmitting a first acoustic signal into the pipeline through the pipeline wall, (b) receiving echoes of the signal, and (c) using the Doppler frequency shift of the received echoes to determine how far from the pipeline inner surface the interface between the deposits and the flowing fluid lies.

Abstract: A novel method of non-destructive die crack inspection of a plastic encapsulated integrated circuit (PEIC) uses a scanning acoustic microscope, such as a C-mode scanning acoustic microscope. To generate scan of a die surface of the PEIC, the width of a data gate of the microscope is set to scan only the die surface. Then, the data gate is moved to cover only die subsurface reflection area on a screen of the microscope, and scan of the die subsurface is generated.

Abstract: A nondestructive bond testing system is implemented using a pulse laser that sends a single or multiple pulse(s) of controlled magnitude and bombards an object of interest causing a thermoelastic excitation response. This excitation in turn induces an ultrasonic propagation along or through the surface material. By detecting, capturing and interpreting these thermoelastic propagation signatures, the attachment condition of the joining materials is determined. The technique is a significant improvement over traditional mechanical pull, shear or contact type techniques. The techniques are implemented in automated high speed inspection systems suitable for real time manufacturing application. Particular applications include evaluating material joining in microelectronics manufacture (such as ball bonds) and thin coating processes.

Abstract: A device for detecting chemical substances includes a plurality of sensors arranged in an array. The sensors are connected to respective oscillator circuits which drive the sensors, and the oscillator circuits are coupled to a power multiplexer which provides the circuits with power according to a timing pattern such that not all of the oscillator circuits are activated at any one time. Preferably, only one oscillator circuit is activated at any given time. This multiplexing arrangement saves power and substantially eliminates cross talk between the oscillator circuits. The oscillator circuits are preferably application specific integrated circuits (ASICs), and the sensors are preferably surface acoustic wave (SAW) devices. In use, the SAW sensors are exposed to a gas, such as air, containing the chemical substance to be detected. Signals from the SAW sensors are analyzed to identify the chemical substance.

Abstract: A two-dimensional ultrasonic transducer for forming images. The transducer has a plurality of transducer elements for producing ultrasonic bursts in a predetermined manner, and receiving reflected ultrasound from the subject under examination due to the ultrasonic bursts. The plurality of transducer elements are arranged in an array into columns and rows, the columns of the transducer elements arranged in a scanning plane for scanning the subject under examination in order to form a two-dimensional profile of the subject, and the rows of the transducer elements having groups of symmetrically arranged transducer elements being oriented in a elevational plane. Each of the groups of symmetrically arranged transducer elements are mechanically arranged to have a focus at specified locations distant from the transducer which is within the subject under examination.

Abstract: A measuring apparatus uses a variable and fixed frequency pulsed phase locked loop to measure the phase shift caused by a delay path to a high degree of accuracy. This accurate measurement of total phase change through greater than 360 degrees allows the apparatus to measure strain in bolts or other materials. The apparatus is able to identify features on a waveform through pattern recognition, and measure untracked phase differences with better reliability than simple thresholding techniques permit.

Abstract: An ultrasonic testing system can receive data from at least two ultrasonic transducers and process the data in parallel to each other. The testing system can compress the data by a fixed ratio by storing the value of the sample having the highest-amplitude out of a group of samples. The testing system can also provide threshold-based run-length encoding by compressing data by only storing samples which exceed a user-defined threshold value as well as a user-defined range of samples surrounding said samples. The ultrasonic testing system also provides a hardware gate for storing a peak amplitude and associated time-of-flight for a user-defined interval and a gate for storing the time-of-flight for the first excursion of the data through a user-defined threshold and interval. The operation of these gates or the storage of waveform data may be delayed by a constant delay or until the data exceeds a user-selectable threshold during a user-selectable time interval.

Abstract: An ultrasonic sensor having a support structure of first and second walls with a gap of fixed distance therebetween. A piezoelectric element for transmitting and receiving ultrasonic energy is bonded to the inner face of one of the walls and the energy transmitted across the gap is reflected from the other wall back to the element. Two timing windows are set, one for the time of energy transmission across the gap with liquid present and the other with the gap being dry. The received energy at the time of the window indicating the dry gap condition is used as a self-test signal to check element dis-bonding. In a sensor with two elements, one bonded to each of the support walls, one element serves as the transmitter and the other as the receiver.

Abstract: In an ultrasonic inspection apparatus for detecting a flaw present in a target object (2) on the basis of an echo signal (b) from the target object (2), a high-frequency echo signal (b) output from an ultrasonic transmit-receive unit (1) is A/D-converted at a high sampling frequency (f.sub.S) in only a predetermined measurement time interval (T.sub.M) in a repetitive period (T.sub.O) of an ultrasonic pulse (a) and is temporarily stored in a storage unit (12). Thereafter, the sampling data is read out at a read frequency (f.sub.R) lower than the sampling frequency (f.sub.S). A digital signal process for noise reduction using a first digital filter (18) or a synchronous adding/averaging circuit (27) is performed to only data in the measurement time interval (T.sub.M). As a result, noise included in the echo signal (b) is considerably reduced while on-line inspection is kept performed.

Abstract: A method and apparatus for non-contact determination of the weight per unit area and the thickness of thin materials. This involves directing an ultrasonic wave at the material and measuring the proportion of sound energy that passes through the material. The process is distinguished by the fact that the time intervals between the ultrasonic pulses are greater than the propagation time. At the receiver only the signals that exceed a certain amount and are shorter in duration than the propagation time are evaluated.

Abstract: A method and apparatus is provided to detect the position of an object, such as a container, within a multidimensional target space above which is a dispensing spigot to dispense water, ice, or other beverage. The dispenser control is also applicable to other applications, for example, dispensing soap in response to the detecting of human hands. The system has a transceiver emitting pulses of ultrasonic waves, a portion of which are reflected by the object in the target space and detected by the transceiver, and a processing circuit for determining the relative strength of the reflected signals and the time it takes an ultrasonic wave to be emitted, reflected, and received by a transceiver. The received signal is checked to determine if the amplitude of the reflected ultrasonic wave is consistent with an object occupying the target space. A timer circuit creates a timing window which further defines the target space.

Abstract: A method and apparatus for detecting and measuring gelled material (i.e. gelled pig) as it passes through a tubular by generating ultrasonic pulses at timed intervals which, in turn, are transmitted through said tubular and materials flowing therethrough at a fixed point along said tubular. These pulses are received after they have passed through said tubular and the materials and are processed to identify those pulses which travel through said gelled material as said gelled material passes by said fixed point. From the number of identified pulses, the length of the gelled pig can be determined.

Abstract: A preamplification and impedance matching circuit for an electromagnetic acoustic transducer includes an impedance matching section of the circuit having input terminals for receiving radio frequency power from a radio frequency power source. A matching transformer, which is a step-down transformer, is operatively connected to the input terminals. Diode networks are operatively connected to the matching transformer and output terminals which lead to the coil of the transducer. Signal responses emitted by the transducer coil are transmitted to a preamplifier section of the circuit. Choke coils or resistors are used to limit radio frequency power entry into the preamplifier section of the circuit.

Abstract: A time-interleaved method for efficient operation of an acoustic wave sensor array couples each sensor repetitively and one at a time via a digitally-addressable analog switch, or multiplexer, to a single oscillator driver to form an oscillation circuit. A frequency of oscillation for each acoustic wave sensor is determined. The frequency for each acoustic wave sensor then is converted into a measurement value for the parameter to which each acoustic wave sensor is sensitive.

Abstract: An ultrasonic transducer for measuring a property of a material within a defined space has a function of a velocity at which ultrasonic signals travel through the defined space includes a controller. The controller is adapted for coupling to a plurality of ultrasonic transducers. The controller include a multiplexer for selecting one of the plurality of ultrasonic transducers, signal processing means for processing an output of the selected ultrasonic transducer and controller means for providing parameters to the signal processing means based upon the selected ultrasonic transducer. The controller couples to a two wire 4-20 mA communication loop. The controller periodically excites the ultrasonic transducer to obtain a measurement. The controller stores power received from the two wire communication loop and excites the transducer using stored power. The controller is capable of providing power which exceeds that available directly from the two wire communication loop for a brief period of time.

Abstract: A system and method for dynamically and non-destructively measuring the longitudinal stresses in a rail of a continuous rail track includes an ultrasonic transmitter which transmits coded focused shear pulses through a rail which are subsequently received by a linear array of sensors. A displacer adjusts the separation between the transmitter and the sensors to maximize the signal intensity received by a centrally located one of the sensors. A data processor, in conjunction with a rail height detector, a rail temperature detector, and a rail splice detector, dynamically determines the longitudinal stresses in the rail as a function of the velocity of propagation of the pulses, the stress free temperature (SFT) of the rail, and activates a rail marker to mark portions of the rail having unacceptable longitudinal stresses. Stress and related data is recorded on a data log. A video camera provides observed rail separation data to the data processor.

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 time gate ultrasonic sensor measures a physical property of a material, such as the presence of the material, within a defined space. The sensor includes at least one transducer connected to a support structure and positioned generally adjacent the defined space for transmitting and receiving ultrasonic signals across the defined space. The ultrasonic signals include a main waveform which travels across the defined space and a self-test waveform which travels along the support structure. The sensor monitors the received ultrasonic signals during a main time window to sense whether the main waveform is present in the received signals. The sensor senses the physical property of the material within the defined space as a function of whether the main waveform is present within the time window. The sensor performs a self-test each measurement cycle by determining whether the self-test waveform is present during a self-test time window which is different from the main time window.

Abstract: An ultrasonic unipolar pulse/echo instrument uses active switches and a timing and drive circuitry to control electrical energy to a transducer, the discharging of the transducer, and the opening of an electrical pathway to the receiving circuitry for the returning echoes. The active switches utilize MOSFET devices along with decoupling circuitry to insure the preservation of the unipolar nature of the pulses, insure fast transition times, and maintain broad band width and time resolution. A housing contains the various circuitry and switches and allows connection to a power supply and a movable ultrasonic transducer. The circuitry maintains low impedance input to the transducer during transmitting cycles, and high impedance between the transducer and the receiving circuit during receive cycles to maintain the unipolar pulse shape. A unipolar pulse is valuable for nondestructive evaluation, a prime use for the present instrument.

Abstract: To reduce the power consumption of the ultrasonic probe, the number of transducers to be driven at any given time is controlled. More specifically, all transducers are driven, whereby the probe transmits the ultrasonic beams to a subject through an acoustic lens provided in front of the probe. When an echo signal reflected from an interior portion of the subject and a multi-echo signal reflected from the acoustic lens are detected, the transducers whose operation is required to obtain a tomographic image of the subject are driven. When only the multi-echo signal is detected, fewer transducers are driven.

Abstract: An interface circuit for use in connecting a high frequency piezoelectric transducer to an input stage of an echo ranging system is described. The circuit includes first, second and third control transistors which are selectively switched by a state controller to control the operation of the circuit. The first transistor is controlled to generate a coherent acoustical pulse at a first predetermined time. The second transistor is controlled to damp the transducer output at a second predetermined time following the first predetermined time. The third transistor serves to clamp the input stage of the echo ranging system to ground until the pulse signal has been effectively transmitted. This operation insures the transducer is in a condition to immediately receive an echo pulse despite the proximity of the transducer to the target whose range is being measured.

Abstract: Nondestructive ultrasonic testing systems and methods include data processing capabilities which allow time division multiplexing of several transducer channels by a smaller number of gates for signal processing, and time division multiplexing the outputs of the gates for subsequent evaluation.

Abstract: Variable focusing in a phased array sector scanner is provided by selectively delaying the operation of a plurality of analog to digital converters thereby skewing sampled data. The skewed sampled data is then stored in a digital memory, and further focusing of the data is realized by selectively delaying the readout of data from the memories.

Abstract: Method and apparatus are disclosed for measurement of the thickness of a workpiece by periodically transmitting ultrasonic pulses into a workpiece by means of a probe provided at its front surface with a delay material, receiving ultrasonic echo pulses reflected from the bottom surface of the workpiece, measuring the period of time corresponding to the period of time elapsed from the transmission of each ultrasonic pulse to the reception of its related echo pulse minus the period of time corresponding to the propagation time of the ultrasonic pulse through the delay material which is specified by the setting of a zero-point adjusting circuit, calculating the thickness of the workpiece from such measured time periods, and displaying the thickness value thus calculated on a display.

Abstract: A gated peak detector capable of operating at frequencies of the order of 50 Mhz. and with pulse repetition rates of the order of 10,000 pulses per second includes high speed positive and negative peak detectors driving corresponding sample and hold circuits, the outputs of which are combined in a differential amplifier, the output of which is digitized to provide an output digital signal corresponding to the peak-to-peak value of the input waveform. An automatic polarity selector circuit sums the outputs from the sample and hold circuits, compares the sum to a reference voltage, and controls switches connected to the outputs of the sample and hold circuits and to the input of an analog sample and hold circuit which provides an analog output signal corresponding to the larger of the detected peak values.

Abstract: The disclosure relates to a circuit using a relatively inexpensive relatively slow sampling rate A-D converter which provides resolution which is far superior to that obtained normally from the A-D converter being used. This is accomplished by providing a variable delay circuit wherein the delay is controllable. The maximum delay of the delay circuit is matched to the sampling rate of the A-D converter being used. The delay is then varied so that trigger pulses for commencing a sampling cycle are commenced at different points along the wave or information signal being sampled so that, after several different amounts of delay have been provided to information initiating triggering pulses, the information signal will have been sampled at various points therealong to provide the higher degree of resolution required while still using a relatively inexpensive slow sampling rate A-D converter.

Abstract: A distance-determining detector and method. A piezoelectric ultrasonic transceiver sends out pulses and receives their reflection and produces an analog output and a trigger output. The analog output is given effect only when it exceeds a threshold level, as shown by a comparator. The trigger output is used for disabling detection during transmission of the transmitter pulse and for producing a time interval during which the analog output is valid, when enabled. An AND gate is connected to the comparator and to the enabled trigger output. Clock pulses are counted, and a flip-flop circuit is connected to the counter and to the output from the AND gate. A multiplying digital-to-analog converter is connected to the flip-flop circuit for determining the distance. There may also be temperature compensation and scaling for the converter for validating the output thereof over a wide range of temperatures.

Abstract: The ultrasonic weld inspection method comprises transmitting an ultrasonic wave through the molten metal portion of the weld while the weld is being formed and determining if a weld defect is present in the molten metal. If no defect is detected in the molten metal, the welding process continues. However, if a defect is detected in the molten metal, the welding electrodes remain at that position until the defect has dissipated. In this manner, defects are removed from the weld before the weld metal solidifies.

Abstract: A method and a device for determining the weight per unit area and/or the thickness of thin material in sheets, for example banknotes, by aid of ultrasonic waves. The device comprises a single- or multi-channel transmitter-receiver arrangement in which the banknote passing through is exposed to a pulsating sound field. The sound is transmitted to the receiver via the banknote which is set vibrating by the sound. For the evaluation of the receiver signal a time interval dependent on the sound propagation time between the transmitter and the receiver is defined which begins when the primary sound arrives at the receiver and ends before reflected portions of the transmitted sound or portions of sound from adjacent transmitters arrive at the receiver. During the time interval the receiver signal which is free from noise signals is integrated. The integration value is a measurement of the density per unit area of the test material.

Abstract: An ultrasonic test instrument includes a pulse generator, a receiver, a cathode ray tube screen display and a time gate means providing a gated time interval for viewing only echo signals which arise from a predetermined workpiece region under test. The time gated interval is shown as a horizontal gate bar display on the screen and the length of the bar being indicative of the gated time interval. Circuitry provided generates a reference signal to cause the gate bar to appear at a height commensurate with the echo signal received in the gated intervals having the highest peak amplitude. Unless reset, the amplitude of the gate bar remains at this peak value although subsequent echo signals may have a lower amplitude.

Abstract: In an acoustic microscope wherein a piezoelectric transducer disposed on one face of an ultrasonic wave focusing lens radiates an ultrasonic wave into the lens and also converts into an electric signal a reflected wave from a specimen arranged on the side of the other face of the lens, a reflected wave from the interface of the lens and the reflected wave from the specimen are caused to interfere with each other.

Abstract: A tracking generator 21 is slaved to a spectrum analyzer 23 to produce an input signal having a frequency that follows the frequency of the spectrum analyzer sweeping local oscillator 22. The input signal is gated to a transducer 26 by a transmitter gate 25 to produce ultrasonic waves in the sample 28. The resulting ultrasonic echoes are converted into electrical signals by the transducer and then gated into the spectrum analyzer by receiver gate 29. This arrangement produces spectra that are equivalent to shock-exciting the transducer with a true delta function shock-excitation.