Abstract: An ultrasonic meter for measuring a flow rate or flow volume includes a fluid inlet, a fluid outlet, a flow channel arranged between the fluid inlet and the fluid outlet, two ultrasonic transducers and at least one reflector for ultrasonic signals. Ultrasonic transducers are arranged outside the flow channel, entrance and exit openings for ultrasonic signals, each running obliquely relative to the longitudinal axis of the flow channel, are provided between the ultrasonic transducers and the flow channel, and the reflector is arranged on the wall of the flow channel opposite the entrance and exit openings such that it reflects ultrasonic signals of the ultrasonic transducers.

Abstract: A method for detecting a flow velocity of a high-temperature molten fluid can include: collecting a video stream of a high-temperature high-velocity molten fluid, decomposing the video stream into a frame image sequence sorted by time, and extracting a molten fluid Region Of Interest (ROI) from the frame image sequence, extracting a molten fluid outline of the molten fluid ROI, and extracting a characteristic block of the molten fluid outline, and obtaining the flow velocity of the molten fluid based on the characteristic block. A flow velocity detection accuracy can be improved for a molten fluid with a high temperature, a high velocity and a high glossiness.

Abstract: An ultrasonic flowmeter comprising a conduit in a support housing and at least two ultrasonic transducers in a measuring insert which can be inserted into the support housing and the conduit perpendicularly to the conduit. The conduit comprises a circular cylindrical receptacle with a diameter larger than the inside diameter of the conduit and a depth encompassing the inside of the conduit, for inserting the measuring insert into the conduit perpendicular to the flow direction. Four ultrasonic transducers are provided in a wall of the measuring insert, the transducers define at least two measuring paths which cross each other in top view. The transducers are arranged in the measuring insert wall such that ultrasonic signals emitted and received by the ultrasonic transducers on the measuring paths have a transit time difference th?tr dependent on the flow velocity v and/or the flow rate Q of a fluid flowing in the conduit.

Abstract: The invention relates to an ultrasonic transducer comprising an acoustic transformer, wherein the acoustic transformer has a transformer body having a hollow space, and there lies between the hollow space and the medium a membrane, whose center oscillates freely. Furthermore, the invention relates to methods for manufacturing such an acoustic transformer.

Abstract: An ultrasonic flow meter is configured to facilitate replacement of flow measurement electronics. The flow meter includes flow measurement electronics including a plurality of transducer assemblies transmitting and receiving ultrasonic waves through a flow for ultrasonic measurement of the flow and a flow meter body. The flow meter body includes a conduit providing a flow passage through the flow meter body, an electronics receptacle configured to receive the flow measurement electronics to form an electronics housing compartment, a plurality of transducer housings configured to receive transducer assemblies and position one or more transducers of the transducer assemblies relative to the conduit, and at least two pass-through apertures directly between the electronics housing into each of the plurality of transducer housings.

Abstract: A method of calculating a time difference is disclosed. The method includes sampling a first ultrasonic signal (r21) to produce a first sampled signal (y1(i)) and sampling a second ultrasonic signal (r12) to produce a second sampled signal (y2(i)). A first time (LEAD_LAG) is determined between a time the first sampled signal crosses a threshold (?1) and a time the second sampled signal crosses the threshold. The first sampled signal is cross correlated with the second sampled signal to produce a second time (SAMP_OFFSET). The time difference is calculated in response to the first and second times.

Abstract: A sensor assembly is provided for conductivity measurement and ultrasonic temperature measurement. The assembly includes an elongated sensor body aligned along a longitudinal axis extending from an electronics housing. The sensor body has a plurality of elongated electrodes disposed about the longitudinal axis defining a measurement section, and a pair of ultrasonic transceivers mounted to the body in spaced relationship across the measurement section, in which a first transceiver of the pair is attached to a proximal end of the sensor body and a second transceiver of the pair is attached to a distal end of the sensor body across the measurement section. The electronics housing is in operable communication with the plurality of electrodes and to the pair of ultrasonic transceivers to measure fluid parameters within the measurement section.

Abstract: An apparatus and a method for measuring a speed of sound in a fluid in a well bore may include a frame adapted to receive the fluid there through are provided. The apparatus includes an acoustic source mounted on the frame; an acoustic detector to measure a signal propagating through the fluid, the acoustic detector disposed proximate the frame at a known distance from the acoustic source; and a test circuit adapted to synchronize the acoustic detector with a signal propagating through the frame. A method to determine physical properties of a fluid in a geological formation including a shear wave anisotropy in the geological formation and the formation composition using the fluid density and the fluid speed of sound is also provided.

Abstract: Performance of a photonic integrated circuit (PIC) is improved by using at least one electro-optic (EO) device included in the PIC to perform at least one EO conversion operation whereby an information signal is transitioned from a first signal carrier type to a second signal carrier type different from the first signal carrier type. The first and second signal carrier types are selected from the group consisting of an optical signal carrier and an electrical signal carrier. An operating bandwidth of the PIC is increased by performing electrical signal impedance matching operations directly on the at least one optical media substrate. An improved electrical impedance match is thus obtained between the EO device and a second device exclusive of the PIC.

Abstract: A harvester includes an auger tube having a first portion and a second portion adjacent the first portion, an auger flight within the first portion of the tube and terminating prior to the second portion to move grain to the second portion, a window along the second portion of the tube and a camera to capture images of grain within the second portion of the tube. A computing device determines grain mass flow based upon the captured images, a dimension of the second portion of the tube and a grain density factor.

Abstract: A method of ultrasonic clamp-on flow measurement according to the transit time difference method and apparatus for the implementation of the method, wherein the electromechanical transducer element of at least one of the two acoustic transducers is comprised of at least two array elements and a correction factor is determined by comparing the transit times between the acoustic transducers while using different array elements.

Abstract: An ultrasonic flow meter comprises a cavity disposed in the wall of a flow tube. This cavity is preferably elongated along a direction perpendicular to a flow axis and has a flat interior surface portion proximal an interior surface of a wall of the flow tube. A piezoelectric transducer has a surface bonded to the flat interior surface portion of the cavity so as to transmit and receive acoustic signals through a thin window in the wall of the flow tube. An encapsulant, which may be combined with other elements, such as a mechanical strengthening piece, bonds the second side of the piezoelectric wafer to a second surface of the cavity. In a particular preferred embodiment, the cavity may be a dovetailed groove cut into a wall of the flow tube.

Abstract: An apparatus and method for noninvasively detecting the presence of solid particulate matter suspended in a fluid flowing through a pipe or an oil and gas wellbore are described. Fluid flowing through a conduit containing the particulate solids is exposed to a fixed frequency (>1 MHz) of ultrasonic vibrations from a transducer attached to the outside of the pipe. The returning Doppler frequency shifted signal derived from the scattering of sound from the moving solid particles is detected by an adjacent transducer. The transmitted signal and the Doppler signal are combined to provide sensitive particulate detection. The magnitude of the signal and the Doppler frequency shift are used to determine the particle size distribution and the velocity of the particles. Measurement of the phase shift between the applied frequency and the detected Doppler shifted may be used to determine the direction of motion of the particles.

Abstract: A method of and apparatus for monitoring fluid flow passing within a pipe is provided. The method includes the steps of: a) providing a flow pressure value and a flow temperature value for the fluid flow within the pipe; b) providing a fluid flowmeter operable to be attached to an exterior of the pipe; c) providing a processor adapted to include an equation of state model for the pressure, volume, and temperature properties for the fluid flow, and further adapted to receive composition data values for the fluid flow, the flow pressure value, and the flow temperature value, and the flow velocity signals from the flowmeter; and d) determining a volumetric flow rate of one or more phases of the fluid flow.

Abstract: An ultrasonic flow sensor for use in a fluid medium is described. The ultrasonic flow sensor includes at least two ultrasonic converters which are situated in a flow tube offset relative to one another, longitudinally with respect to a flow of the fluid medium. The ultrasonic flow sensor also includes a reflection surface, the ultrasonic converters being set up to exchange ultrasonic signals via simple reflection on the reflection surface. In addition, a deflection device is provided between the ultrasonic converters which is set up to essentially suppress parasitic ultrasonic signals, which are reflected from the reflection surface and which strike the deflection device, by deflection away from the ultrasonic converters.

Abstract: An edge of a piezoelectric disk transducer is biased into an external wall of a flow passage by a spring. The disk is then driven at a radial mode resonant frequency to project acoustic energy into fluid flowing in the passage. This arrangement is compatible with several types of fluid flow sensors such as transit time, Doppler, and vortex shedding flow meters.

Abstract: A method for determining the starting instant (t0) of a periodically oscillating signal response (E2; E2?), wherein the signal response comprises a first set of half periods (E2a-d; E2?a-d) having a polarity equal to a polarity of the first half period (E2a; E2?a) in the signal response, and a second set of half periods (E2e-h; E2?e-h) having a polarity opposite to the polarity of the first half period (E2a; E2?a) in the signal response. The method comprises the steps of: determining a peak half period (E2e; E2?f) as the half period with the highest amplitude in a selected one of the first and second sets; determining a zero-crossing instant (ZC1; ZC?1) of the signal response occurring a known time distance from the peak half period (E2e; E2?f); determining the starting instant (t0) of the signal response (E2; E2?) based on the zero-crossing instant (ZC1; ZC?1) and a relationship between the peak half period (E2e; E2?f) and the starting instant (t0).

Abstract: A measuring system for determining and/or monitoring flow of a measured medium through a measuring tube, wherein the measuring system includes: at least one control/evaluation unit, which, based on ultrasonic measurement signals, or based on measurement data derived from the ultrasonic measurement signals, ascertains volume, and/or mass, flow of the measured medium flowing in the measuring tube; and a sensor housing, which surrounds a first ultrasonic sensor and at least a second ultrasonic sensor. At least the first ultrasonic sensor is seated shiftably in the sensor housing; wherein the measuring system further includes a sensor holder, which is securable on the measuring tube and includes a securement mechanism for the releasable securement of the sensor housing on the sensor holder. The sensor housing forms with the ultrasonic sensors a unit securable on the sensor holder and releasable from the sensor holder.

Abstract: An example method for detecting an analyte in a sample of a bodily fluid includes the steps of exposing the bodily fluid sample to electromagnetic energy to cause a thermoelastic expansion in the analyte, and detecting a photoacoustic signal in the sample that results from the thermoelastic expansion.

Abstract: A method and apparatus is disclosed that guides a user through a sequence of steps that will allow the user to complete a predefined task using the flow meter. The steps include: selecting a predefined task, displaying a sequence of steps that directs the user through a process for using the Coriolis flow meter to complete the predefined task, and operating the Coriolis flow meter in response to the sequence of steps to complete the predefined task.

Abstract: A fluid flow meter is described that uses thermal tracers to measure flow speed. For fluid flowing through a conduit, the fluid is heated at a heating location in the conduit with a time-dependent heating strength. A speed of sound in fluid flowing in the conduit is measured at multiple sensing locations downstream from said heating location. The flow speed of the fluid is determined from a delay with which the time dependence is detected in the sound speeds measured at the sensing locations. A frequency of the variation of heating strength that is used to determine the flow speed is selected automatically based on the flow speed and/or other circumstances.

Abstract: The invention relates to an ultrasonic sensor for measuring flow rates in liquid melts at high temperatures. The aim of the invention is to provide an ultrasonic sensor for carrying out local, continuous, reliable rate measurements in hot melts. To achieve this, the ultrasonic sensor contains an ultrasonic waveguide that is connected to the piezoelectric transducer and consists of a material with low acoustic damping properties in a temperature range relevant for the area of application of above 200 DEG C, said material being chemically resistant to the melt. In addition, the end face of the ultrasonic waveguide facing the melt is closed and can be wetted by the melt.

Abstract: An example method for detecting an analyte in a sample of a bodily fluid comprises the steps of exposing the bodily fluid sample to electromagnetic energy to cause a thermoelastic expansion in the analyte, and detecting a photoacoustic signal in the sample that results from the thermoelastic expansion.

Abstract: A method and apparatus is disclosed that guides a user through a sequence of steps that will allow the user to complete a predefined task using the flow meter. The steps include: selecting a predefined task, displaying a sequence of steps that directs the user through a process for using the Coriolis flow meter to complete the predefined task, and operating the Coriolis flow meter in response to the sequence of steps to complete the predefined task.

Abstract: One embodiment provides a flow meter including an airfoil movably secured in the airflow path of a fan in an electronic system. The airfoil is configured to generate a lift component in response to the airflow. A sensor engages the airfoil and generates a signal in relation to the movement of the airfoil. Airflow parameters such as volumetric airflow rate and turbulence may be identified by an analysis of the movement of the airfoil.

Abstract: A transformer board is disclosed. In some embodiments, the transformer board includes a base, a circuit board, a transformer having a first and second winding, a first and a second connector, a ribbon cable and a nonconductive fill material. The base has a recess within which the circuit board is positioned. The transformer is mechanically coupled to the circuit board. The first connector is configured to electrically couple to transducers within a pressure boundary of an ultrasonic flow meter and is electrically coupled to the second winding of the transformer. The ribbon cable is electrically coupled between the first winding of the transformer and the second connector. The nonconductive fill material is contained by the recess and encases the circuit board, the transformer, the coupling of the first connector to the second winding of the transformer, and the coupling of the ribbon cable to the first winding of the transformer.

Abstract: An ultrasonic measurement system for measuring a flow in a conduit. Spaced ultrasonic signal transmitters are configured to launch a ultrasonic beams having a center axis of maximum intensity. Receiving transducers are configured to receive modulated signal energy from the beams and are located off the center axis of the beams to increase the modulation of the signal energy and to produce receiver output signals. A processing subsystem is configured to correlate the receiver output signals to determine a time delay indicative of the flow velocity in the conduit.

Abstract: The invention relates to a fluid meter (1) having a measuring tube housing (2), a measuring zone (3) inside the measuring tube housing (2), an ultrasonic transducer configuration of at least one ultrasonic transducer (4 and/or 5) for generating an ultrasonic signal and/or converting an ultrasonic signal passing through the measuring zone (3) into an electric signal and a deflecting device (11) for deflecting the ultrasonic signal in particular in the longitudinal direction of the measuring tube (3) such that the surface normal N of the ultrasonic transducer (4 and/or 5) is arranged so it is inclined laterally based on the top position of the fluid-filled interior of the measuring tube housing (2) in the installed position with the plane E such that the ultrasonic signal does not strike the deflecting device (11) from above in the installed position of the fluid meter (1).

Abstract: An apparatus measures a speed of sound (SOS) in a process flow by characterizing low order acoustic cross modes in the process flow in a conduit. The apparatus includes transducers on the conduit, spaced from each other around the circumference of the conduit. The transducers generate acoustic input signals in the process flow over a range of frequencies. The apparatus includes strain sensors disposed on the conduit, spaced from each other around the cross-sectional circumference of the conduit. An SOS processor is responsive to the transducers and sensors, and is configured to identify cross-mode frequencies of the conduit and to derive therefrom the SOS in the process flow. An entrained air processor is coupled to the SOS processor to indicate a level of entrained air in the process flow.

Abstract: A method for sensing flow within a pipe having an internal passage disposed between a first wall portion and a second wall portion is provided, comprising the steps of: 1) providing a flow meter having at least one ultrasonic sensor unit that includes an ultrasonic transmitter attached to the first wall portion and an ultrasonic receiver attached to the second wall portion and aligned to receive ultrasonic signals transmitted from the transmitter; 2) selectively operating the ultrasonic transmitter to transmit a beam of ultrasonic signal, which beam has a focal point such that within the pipe, the beam is either colliminated, divergent or convergent; and 3) receiving the ultrasonic signals within the beam using the ultrasonic receiver. An apparatus operable to perform the aforesaid method is also provided.

Abstract: A system for monitoring, diagnosing, and/or controlling a flow process uses one or more flow meters based on an array of pressure sensors. A signal processor outputs at least one of a flow signal, a diagnostic signal, and a control signal in response to the pressure signals from the pressure sensors. The flow signal indicates the at least one parameter of the fluid, the diagnostic signal indicates a diagnostic condition of a device in the flow process, and the control signal is effective in adjusting an operating parameter of at least one device in the flow process. The system may be arranged as a distributed control system (DCS) architecture for monitoring a plurality of flow meters based on array-processing installed at various locations throughout a flow process.

Abstract: A method for calibrating a flowmeter, comprising choosing a pipe configuration from a list of pipe configurations, defining a number of diameters downstream from the pipe configuration where a transducer is to be installed, determining an initial curve number for the chosen pipe configuration, wherein the initial curve number corresponds to a predetermined flow profile correction curve, determining a swirl factor for the chosen pipe configuration, and computing a calibration factor for a given Reynolds number.

Abstract: An ultrasonic flow sensor, in particular for determining the flow velocity of a medium flowing through a pipeline, has at least one ultrasonic converter for transmitting and/or receiving ultrasonic signals, an oscillator, which is connected with the ultrasonic converter, and an evaluation unit, which determines a phase shift of the ultrasonic signal that was received, with respect to a reference signal. The evaluation unit includes a plurality of quadrature demodulators, which operate with different demodulation frequencies and each determine phase information about the ultrasonic signal that was received, and when a vernier unit is provided, which determines—based on the individual pieces of phase information—a phase angle or a quantity proportional thereto.

Abstract: An apparatus, system and methodology enable non-intrusive measurement of parameters related to fluid flow in a conduit. An acoustic sensor is located along the conduit and includes a mechanical amplifier having an acoustic input coupled to the conduit and a microphone coupled to the mechanical amplifier. The microphone receives mechanically amplified acoustic energy from the conduit and establishing first signals which are processed for generating second signals which are related to fluid flow in the conduit. The second signals can include quantitative flow data and qualitative data such as change in state and alarms. The second signals can be transmitted wirelessly to a remote site for further processing. Use of low power components and power management enable long term operations on battery power.

Abstract: The invention relates to a fluid meter (1) having a measuring tube housing (2), a measuring zone (3) inside the measuring tube housing (2), an ultrasonic transducer configuration of at least one ultrasonic transducer (4 and/or 5) for generating an ultrasonic signal and/or converting an ultrasonic signal passing through the measuring zone (3) into an electric signal and a deflecting device (11) for deflecting the ultrasonic signal in particular in the longitudinal direction of the measuring tube (3) such that the surface normal N of the ultrasonic transducer (4 and/or 5) is arranged so it is inclined laterally based on the top position of the fluid-filled interior of the measuring tube housing (2) in the installed position with the plane E such that the ultrasonic signal does not strike the deflecting device (11) from above in the installed position of the fluid meter (1).

Abstract: An apparatus and method for measuring a flow velocity profile of fluid traveling in a pipe or conduit uses an ultrasonic wave transmitted from an ultrasonic wave transducer mounted at an angle on the outside of a pipe using a wedge, and made incident onto the fluid in the pipe to measure the fluid flow velocity profile, using the principle that a frequency of an ultrasonic wave, reflected by a reflector existing in the fluid, is changed depending on a flow velocity due to Doppler effect. The transmission frequency and the angle of incidence onto the pipe can be selected to suppress frequency dependence of a measured value due to Lamb wave and allow the flow velocity or flow rate of fluid to be measured with a greater accuracy.

Abstract: A method, apparatus and system are provided to measure the process flow of a fluid or medium traveling in a pipe. The system and apparatus feature a standoff and piezoelectric-based sensor arrangement having a plurality of standoffs arranged on a pipe and a plurality of sensor bands, each arranged on a respective plurality of standoffs, each having at least one sensor made of piezoelectric material arranged thereon to detect unsteady pressure disturbances in the process flow in the pipe which in turn can be converted to the velocity of and/or speed of sound propagating within the pipe, and a cooling tube arranged in relation to the plurality of standoffs for actively cooling the sensor band; and further comprise a processing module for converting one or more sensor signals into a measurement containing information about the flow of the fluid or medium traveling in the pipe, as well as a pump and heat exchanger for processing the cooling fluid flowing through the cooling tube.

Abstract: An elastomeric acoustic coupler formed by molding a thermoplastic or silicone rubber into a recess of a surgical cassette housing. The coupling has a raised pad to aid in the removal of all air between the transducer and the fluid conduit, and to provide an efficient transmission of an ultrasound signal into the fluid conduit.

Abstract: The mass flow rate sensor includes a waveguide disposed in a flow passage having a bluff body facing in an upstream direction. Waves are pulsed along the waveguide for interaction with the fluid. A receiver is coupled to the waveguide to detect a propagated wave and provides a first output signal proportional to the transit time of the propagated wave for determining fluid density. The receiver also provides a second output signal proportional to the shedding frequency of vortices from the waveguide to determine velocity. An electronics module calculates mass flow rate from the velocity times density times area of the flow passage and a constant. In other forms, the velocity is ascertained by transmitting an ultrasonic beam through the shedding vortices to determine vortex frequency which is proportional to velocity.

Abstract: A flow meter, such as a gas meter, for measuring the flow velocity and/or the volumetric through-flow of fluids. The flow meter has a body with connecting flanges for connecting the meter to a pipeline for the fluids. The meter has a tubular center piece that, on its exterior, has at least two receptacles, each of which receives a measuring device. The measuring devices are coupled to a signal processing unit. Electrical cabling between the measuring devices (probes) and the signal processing unit is completely covered against damage from the exterior by partially guiding the cables through bores in walls of the center piece of the flow meter and by covering portions of the cable and protruding sections of the probes with a cap.

Abstract: A body for a flow meter for measuring the flow velocity and/or the volumetric through-flow of fluids. The flow meter body has a tubular center piece with connecting flanges for connection to a pipeline for fluids. On its exterior, the center piece has at least two substantially flat mounting surfaces (18, 20, 22, 24), each of which has at least one receptacle (32, 34; 38, 40, 42, 44) for mounting a probe (35). To enable the use of linearly emitting ultrasound probes in such flow meters, and to use the flow meter as a substitute for prior art flow meters without significant effort and cost, it is proposed to arrange the mounting surfaces (18 and 20; 22 and 24) diametrically opposite each other as a mounting surface pair (18-20; 22-24) so that the probes (35) in the opposing mounting surfaces (18 and 20; 22 and 24) define a measuring path (36, 46, 48). The mounting surfaces (18 and 20; 22 and 24) are parallel to each other and at an angle to a longitudinal axis (26) of center piece (12).

Abstract: A multiphase flow meter distributed system is disclosed that is capable of measuring phase flow rates of a multiphase fluid. The distributed system includes at least one flow meter disposed along the pipe, an additional sensor disposed along the pipe spatially removed from the flow meter, and a multiphase flow model that receives flow related parameters from the flow meter and the additional sensor to calculate the phase flow rates. The flow meter provides parameters such as pressure, temperature, fluid sound speed and/or velocity of the fluid, and the additional sensor provides a parameter indicative of pressure and or temperature of the fluid. Depending on production needs and the reservoir dimensions, the distributed system may utilize a plurality of flow meters disposed at several locations along the pipe and may further include a plurality of additional sensors as well. The distributed system preferably uses fiber optic sensors with bragg gratings.

Abstract: A photoacoustic effect is used in order to measure a flow rate of a flowing medium (M), in particular of natural gas. A light emitter (1) is used to produce in the medium (M) a sound wave (S) which is transmitted by the medium (M) and detected by a sound detector (2). The light emitter (1) is less exposed to the medium (M) than a diaphragm such as used in the ultrasonic method.

Abstract: A low profile transducer (11, 12) is provided for use in flow meter for pipes of small diameter. The transducer (11, 12) has a transducer (18) or other form of transducer which transmits and receives electrical signals of three volts and 1 MHz and converts between these electrical signals and acoustic waves. In one embodiment, the transducer (18) produces surface acoustic waves (SAW), while in another embodiment the transducer (32) produces plate waves known as Lamb waves. These waves are converted to bulk acoustic waves (BAW) transmitted between the pair of transducers (11, 12).

Abstract: An apparatus for measuring a fluid flow velocity vector including a signal generator for generating an oscillating electrical signal, an acoustic transmitter for generating an acoustic signal proportional to the oscillating electrical signal; and at least three acoustic receivers for receiving the acoustic signal and generating electrical signals which are phase shifted by the influence of the fluid flow, and a signal processor for receiving and processing the oscillating electrical signal and the electrical signals generated by the at least three acoustic receivers to determine time delays for each acoustical receiver caused by the influence of the fluid flow which are processed to determine the fluid flow velocity vector components.

Abstract: An ultrasonic Doppler flow-meter comprises a substrate with a piezoelectricity, input- and output interdigital transducers formed on a first end surface of the substrate, and a signal analyzing unit connected between the input- and output interdigital transducers. A second end surface of the substrate is in contact with a liquid. The finger direction the output interdigital transducer is slanting to that of the input interdigital transducer. When an input electric signal with a carrier frequency f0 is applied to the input interdigital transducer, a leaky Lamb wave is excited in the substrate. The leaky Lamb wave is radiated into the liquid in the form of a longitudinal wave, which is reflected back by a material in the liquid. The reflected longitudinal wave is detected at the output interdigital transducer as a delayed electric signal with a Doppler frequency f.

Abstract: A method and system are provided for measuring water current. An acoustically-modulated beam of radiation is transmitted to a target location on the surface of a body of water. As the beam transits the water, acoustic radiation propagates away from the beam towards the surface and experiences a Doppler shift in frequency relative to the acoustic frequency used for modulation. The Doppler shift is caused by current in the water through which the acoustic radiation transits. The Doppler-shifted frequency is measured as an indication of water current.

Abstract: The present invention relates to a method and system for measuring fluid velocity in pipes alternately transmitting two or more ultrasonic frequencies through a pipe wall into a fluid containing scatterers. For each transmission frequency, energy reflected from the scatterers is mixed with the transmission frequency and the result sampled at a rate which is a constant fraction of the transmission frequency. The combination of the Doppler effect on frequencies reflected from the moving scatterers, and the described sampling rate scheme combine to permit isolation of velocity related frequencies from extraneous frequencies in the reflected energy in a computationally efficient manner. A single frequency which represents fluid velocity is extracted from the gathered data, and the fluid velocity readily calculated therefrom using the Doppler formula. The invention provides a system and method for measuring fluid velocity which is simple, reliable, and cost effective.

Abstract: A clamp-on ultrasonic measurement system for a gas or fluid of low acoustic impedance, such as steam, two phase fluid or flare gas includes an ultrasonic signal transmitter which clamps to the steam or gas conduit, and first and second receiving transducers clamped in the shadow zone of the transmitter. The transmitter signal skips within the conduit wall with a characteristic skip distance Lp so ultrasonic signal energy is launched across the flow along plural paths over a region, and at an angle to the direction of flow. The receivers are positioned to receive the signal energy along different ones of said paths, modulated by tags or inhomogeneities in the flowing fluid. Cross correlation of the received signals then yields a peak correlation time interval or time delay from which the flow velocity is accurately determined.

Abstract: A mobile harvesting machine, in particular a forage harvester, has a measuring device for determining a parameter specific to crop material or conveyed material. Here the harvesting machine comprises an attachment for picking up the crop material and at least one implement for working the crop material. The measuring device in the harvesting machine is arranged on the path of crop material between the implement and the region in which the stream of crop material has been brought to its final stream width. In this region it is ensured that the stream of crop material exerts a low pressure on the measuring device. Another advantage is that due to the site of attachment, the pressure difference is minimal for different throughputs of crop material. This arrangement of the measuring device further allows good checking of the measuring device for wear and soiling and is easily accessible in case of possible repairs.