Abstract: An ultrasonic device includes a substrate having a first surface and a second surface having a front and back relationship with the first surface, and provided with an opening penetrating the second surface from the first surface; a vibration film provided over the first surface of the substrate so as to close the opening; a vibration element provided at a position overlapping the opening in the vibration film; and a sound absorbing portion provided over the second surface of the substrate.

Abstract: An inductive heating device (1) for heating an aerosol-forming substrate (20) comprising a susceptor (21) comprises: a device housing (10), a DC power source (11) for providing a DC supply voltage(VDC) and a DC current (IDC), a power supply electronics (13) comprising a DC/AC converter (132), the DC/AC converter (132) comprising an LC load network (1323) comprising a series connection of a capacitor (C2) and an inductor (L2) having an ohmic resistance (RCoil), a cavity (14) in the device housing (10) for accommodating a portion of the aerosol-forming substrate (20) to inductively couple the inductor (L2) of the LC load network (1323) to the susceptor (21). The power supply electronics (13) further comprises a microcontroller (131) to determine from the DC supply voltage (VDC) and the DC current (IDC) an apparent ohmic resistance (Ra), and from the apparent ohmic resistance (Ra) the temperature (T) of the susceptor (21).

Abstract: In a method for wireless communication between a vehicle, particularly a motor vehicle, and an external service facility, wherein at least one communication signal is sent to the vehicle by the service facility, it is provided as essential for the purposes of the invention that the communication signal is a sound signal, and that the communication signal is captured by at least one structure-borne sound sensor installed in the vehicle.

Abstract: A footwear seismic communication unit is provided herein. The unit includes footwear attachable to a foot or feet of a user, including at least one sole portion for placing on a ground and at least one seismic transducer device located within said at least one sole. The unit further includes a processing module, a transmitting interface module, and a receiving interface module.

Abstract: A high-frequency light-generated focused ultrasound (LGFU) device is provided. The device has a source of light energy, such as a laser, and an optoacoustic lens comprising a concave composite layer with a plurality of light absorbing particles that absorbs laser energy, e.g., carbon nanotubes, and a polymeric material that rapidly expands upon exposure to heat, e.g., polydimethylsiloxane. The laser energy is directed to the optoacoustic lens and thus can generate high-frequency (e.g., ?10 MHz) and high-amplitude pressure output (e.g., ?10 MPa) focused ultrasound. The disclosure also provides methods of making such new arcuate optoacoustic lenses, as well as methods for generating and using the high-frequency and high-amplitude ultrasound, including for surgery, like lithotripsy and ablation.

Abstract: This invention concerns an acousto-optic imaging method comprising a step which consists in engraving in a dynamic holographic material a complex index array resulting from the interference of the acousto-optic component of the signal wave and a pump wave of frequency equal to the frequency of the acousto-optic component.

Abstract: A method and device are presented for identifying machines, such as vehicles, based on acoustic machine signatures. An acoustic sensor generates machine-acoustic data about the machine. A machine-signature identifier receives the machine-acoustic data, determines a machine signature from the machine-acoustic data, and identifies the machine based on the machine signature. A machine-signature database, configured to store multiple machine signatures and/or machine-signature templates, may receive and process queries about machine signatures for machine identification. The machine-signature identifier may generate and send an instruction based on the identified machine. The instruction may instruct application of electronic countermeasures or may permit a vehicle to enter a secured area. An acoustic modulator may generate the machine-acoustic data to act as a machine signature. The acoustic modulator may generate the machine signature using an ultrasonic carrier.

Abstract: The present invention provides a method for removing micro-debris generated in a laser machining process operated on machined object and device of the same. The machined object is placed on a movable machining platform within a machining range and machined at a particular machining location. By disposing an acoustic wave generator and a reflector part, or by disposing a plurality of acoustic wave generators, at least two standing waves extending across the machining range and two standing wave nodes are generated. The micro-debris generated from the laser machining process is moved away by the standing waves to concentrate at the standing wave nodes, and subsequently removed from the standing wave nodes.

Abstract: A machine for anticipatory sensing and intervention to avoid swimmer entrapment, with an active pre-entrapment sensor (e.g. ultrasonic) that assesses the relative hazard based on swimmer proximity to the drain cover. An Ultrasonic Transducer launches waves into the suction piping and/or drain system, and receives echoes from the drain cover, swimmer limbs, hair or body, and the water surface parallel to the drain cover. A Transmitter/Pulser electrically energizes the ultrasonic transducer to launch waves into the suction piping and/or drain system, A Receiver/Processor detects the echoes electrical signals from the ultrasonic transducer. and receives echoes from objects of interest beyond the pool drain. A Logic and Control element converts the detected signals into reliable information regarding a swimmer safety/hazard status. An Output provides a pump shutdown command when required. There is also a pool alarm mode to detect, and a panic alert, that a child has fallen in.

Abstract: A technique is provided by which energy is physically/mechanically transmitted down through a wellbore. The transmitted energy is directed downhole along a fluid channel and impinges on an energy converter positioned in the wellbore or at another subterranean location. The energy converter converts the physical energy into electrical energy that can be supplied to a downhole device.

Abstract: This method of detecting the presence of a disruptive object on a stretch of road comprises: a step (66) of enumerating the vehicles simultaneously present on the stretch of road on the basis of data gleaned by a first and a second vehicle detector placed respectively at an entrance and at an exit of this stretch, and a step (74) of instructing the activation of an image processing step, triggered automatically as a function of the enumeration.

Abstract: The Invention is a reinforced plastic sonar dome having a low acoustical insertion loss combined with sufficient mechanical strength. Acoustical and structural fibers are stochastically mixed and formed into a blended yarn. The blended yarn is woven into a blended fabric. The blended fabric is ordered into a stack having multiple layers of blended fabric. The blended fabric is incorporated into a polymer resin while the polymer resin is in liquid form using a vacuum assist. The acoustical fibers and the vacuum assist modify the acoustical properties of the resulting composite sonar dome.

Abstract: A seismic streamer cleaning device includes a means for converting motion of water past a seismic streamer into movement of the device as the streamer is towed through the water. A cleaning element is cooperatively engaged with the device and an exterior surface of the streamer. In one embodiment, the cleaning element includes brush bristles.

Abstract: An improved acoustic window for an acoustic waveform passage having a generally uniform transmission loss at an angle of incidence of between −40° and +40°. The composition is formed from at least one core layer and at least two septa, with the core layer being a material having a generally low-acoustic-impedance, a static shear modulus between about 1.0 psi (0.007 MPa) and about 15,000 psi (103 MPa), a transverse (or through-thickness) sound velocity for the acoustic waveform of between about 700 and about 2200 meters per second, a transverse acoustic impedance of less than or equal to 4×106 kilograms per square meter-second, and a shear loss factor of greater than 0.02, the septa being composed of at least one ply of a material, preferably a graphite fiber reinforced epoxy composition, having a transverse acoustic impedance of less than 60×106 kg/m2-sec, a tensile modulus of more than 0.5×106 psi, a thickness of less than 0.

Abstract: The object of the present invention is to provide an individual authentication method and apparatus that use no bulky apparatuses, are insusceptible to forgery, and use an auditory organ which is almost independent of health condition and aging, is little subject to physiological rejection, and exists in everyone.

Abstract: An acoustic spectra personal identification system comprising acoustic signal generating means, acoustic transducer means and computer means including storage means, processor means and acoustic signal analysis means, whereby a data base may be generated and maintained that stores acoustic resonance spectrum information specific to selected body parts of known individuals, for comparison against newly captured acoustic resonance spectral information obtained from an identification subject arid for determination whether said subject's acoustic spectra matches that of a data base participant.

Abstract: The opto-acoustic generator of ultrasound waves comprises an optical fiber associated to a laser-energy source, and an opto-acoustic transducer which is applied to said fiber and is designed to be impinged upon by the laser beam and to absorb partially the energy, converting it into thermal energy, thus bringing about the formation of ultrasound waves by the thermo-acoustic effect. Said opto-acoustic transducer consists of a layer or film containing prevalently graphite, which is applied on a surface of said optical fiber.

Abstract: The opto-acoustic generator of ultrasound waves comprises an optical fiber associated to a laser-energy source, and an opto-acoustic transducer which is applied to said fiber and is designed to be impinged upon by the laser beam and to absorb partially the energy, converting it into thermal energy, thus bringing about the formation of ultrasound waves by the thermo-acoustic effect. Said opto-acoustic transducer consists of a layer or film containing prevalently graphite, which is applied on a surface of said optical fiber.

Abstract: Arrangement and method for controlling audio reception by occupants of a vehicle in which the position of any occupants is determined and the entertainment system controlled to provide specific sound for the occupants based on the determined positions of the occupants. Sound generating components of the entertainment system are automatically adjustable based on the determined position of the occupants. A hypersonic sound generating system may be used wherein ultrasonic frequency generators generate ultrasonic waves which mix with ultrasonic waves generated by another ultrasonic frequency generator to thereby cause the creation of new audio frequencies in an area determined based on the position of the occupants. In addition, the presence and direction of unwanted noise may be detected and sound created to cancel the unwanted noise in the area including the determined positions of any occupants.

Abstract: A severe weather detection apparatus for detecting severe weather and method of detecting and warning of approaching severe weather conditions is provided. The severe weather detector apparatus includes a barometric pressure sensor and computerized means for calculating the rate of change in the barometric pressure. By monitoring and deriving a value representative of the rate of change in the barometric pressure over time, a threshold is established and compared to the current rate of change in the barometric pressure. The derived rate of change is compared to a value stored in the device which reflects approaching severe weather conditions. Rates of change which may indicate the approach of severe weather activate a voice-enunciated alarm that announces the potentially dangerous barometric activity. The severe weather detection apparatus is portable and suitable for battery power and installation in the same manner as a home smoke alarm or carbon monoxide detector.

Abstract: A portable reel apparatus for use with towed sonar towfish and similar apparatus. The reel apparatus of the invention can be used on small watercraft without requiring mounting to the deck, and can be quickly and easily moved and stored on-board or removed from the watercraft. The portable reel assembly comprises a frame assembly, a spool rotatably mounted within the frame assembly, an extensible boom, and an electronic interfacing assembly for maintaining communication between a sonar cable through the spool to a computer. The apparatus can be moved or repositioned between a first, deploying position and a second, storage position. The frame assembly is preferably wheeled for transporting the apparatus, and a motor for driving the spool is preferably included within the frame assembly.

Abstract: A method for land seismic data acquisition is provided, together with a seismic cable and a cable spool vehicle for use in the method. In performing the method, the cable spool vehicle mechanically deploys seismic cable with attached sensors according to a desired geophysical spread and at a rate dependent upon the speed of movement of the vehicle substantially without tension in the cable. The cable spool vehicle also allows mechanical pick-up of the seismic cable together with the sensors after the seismic data acquisition.

Abstract: The invention is a processor based analysis system with appropriate interface that includes multiple fish surrogates that each have a plurality of piezoelectric and triaxial accelerometer sensors for emulating sensory organs of a particular fish. The multiple fish surrogate array is immersed in flowing water intakes of a hydraulic structures such as intakes, intake bypasses, and diversion structures, and natural geological formation such as riffles, shoal areas, and pools. The invention is an interface system for data acquisition analysis and perspective display of acoustic and fluid dynamic data in or near these hydraulic structures and/or natural formations. To accomplish this, multiple sensors in each of the fish-shaped surrogate physical enclosures that form the array are deployed at the same time to describe a fish's aquatic environment at the hydraulic structure location.

Abstract: A rugged ultrasonic sensor is provided which is capable of detecting objects in very close proximity to the sensor. This close proximity detection includes the detection of objects which are immediately adjacent the sensor housing. Such close range operation is achieved by tailoring the transducer to operate at previously undesirable conditions, including low Q and high frequency. Such operating conditions allow the resonating characteristics of the transducer not to interfere with close range operation.

Abstract: A sonic transducer shroud is shaped to present an inclined surface to rising bubbles and other matter during water treatment. Attached to the face of the sonic transducer, the shroud prevents the bubbles and other matter from being trapped on the transducer measurement surface and subsequently interfering with echo reception. The shroud has acoustic properties that are matched to the water such that the shroud is substantially acoustically transparent.

Abstract: An apparatus for placing geophones beneath the surface of the earth includes a machine frame that supports an elongated probe rod. The probe rod is dimensioned to reach a selected subterranean earth layer. The rod has upper and lower end portions. A geophone holder is positioned at the lower end of the rod for holding a geophone and its cable. A plurality of drive wheels carried by the frame transport the rod between the upper and lower positions. The drive rollers include at least an opposed pair of upper wheels and an opposed pair of lower wheels. The wheels are loaded with an adjustable spring pusher so that extensive pressure can be applied from the drive wheels to the pipe for gripping and driving the pipe even when muddy. A gear train interconnects all of the driving wheels so that all of the wheels rotate at the same rotational speed. A gear train preferably includes six gears including a pair of upper gears, a pair of lower gears, and a pair of intermediate drive gears.

Abstract: A sound absorption device in accordance with this invention includes an enclosure loosely containing hollow beads. Preferably, the hollow beads have openings, and differ with respect to the volume of the hollow space defined by the walls of the beads, the wall thicknesses of the beads, the size of the openings of the beads and/or the number of openings on the beads. Through Helmholtz resonance, vorticity and tortuous path scattering, the beads damp sound waves over a broad range of frequencies. Preferably, the beads are formed from a material able to withstand relatively high temperatures, such as ceramic or nickel. The beads can thus be used to damp sound in applications which generate significant heat in addition to sound, such as aircraft engines, rocket motors or other loud, heat-generating sources, for example. Also, by forming the beads from a material with a relatively low thermal conductivity, the beads can also be used for thermal insulation in addition to sound absorption.

Abstract: A wireless boundary monitor system used to monitor the integrity of a boundary surrounding an area uses at least two housings having at least one transmitting means for emitting ultrasonic pressure waves to a medium. Each of the housings has a plurality of receiving means for sensing the pressure waves in the medium. The transmitting means and the receiving means of each housing are aimable and communicably linked. At least one of the housings is equipped with a local alarm means for emitting a first alarm indication whereby, when the pressure waves propagating from a transmitting means to a receiving means are sufficiently blocked by an object a local alarm means or a remote alarm means or a combination thereof emit respective alarm indications. The system may be reset either manually or automatically. This wireless boundary monitor system has useful applications in both indoor and outdoor environments.

Abstract: A seismic cable connector adapter assembly for coupling sub-diameter seismic streamer-cables to standard-sized instrumented cable connector modules.

Abstract: The apparatus of this invention are multiple fish surrogates that each have plurality of piezoelectric and triaxial accelerometer sensors for emulating sensory organs of a particular fish. The multiple fish surrogates are immersed in flowing water intakes of a hydraulic structure such as: intakes, intake bypasses, and diversion structures; or also natural geological formation such as riffles, shoal areas, and pools. The invention is used for acquisition of acoustic and fluid dynamic data in or near these hydraulic structures and natural formations. To accomplish this, multiple sensors in multiple fish-shaped physical enclosures are deployed at the same time to describe a fish's aquatic environment at locations such as in proximity to a dam's intake. Since such an intake exhibits turbulent and high energy flow fields that cannot be characterized by a single sensor, many sensor bodies are required for a complete characterization of the environment.

Abstract: An acoustic baffle for reflecting sound waves and rejecting background interference noise for use with a hydrophone array. The baffle utilizes a plurality of lenticular resilient elements embedded in a compliant foam elastomer compound. The embedded elements provide control of overall baffle compliance for submarine applications, particularly for high hydrostatic pressure operation. The resilient members are formed from pairs of resilient lenticular shaped elements which are integrally bonded to a highly damped constrained viscoelastic layer to provide uniform noise reduction performance over a broad frequency range. The pairs of elements are joined at their ends by compliant end caps which provide minimum constraint on the motion of the ends, thus limiting bending stresses in the elements.

Abstract: Acoustic signals and hydraulic pressure variations which influence fish bvior in bodies of water are measured and recorded by apparatus simulating a fish immersed in water, fitted with piezoelectric transducers and connected by wiring to remote amplifying and recording means. Such data are correlated with fish behavior for the purpose of developing methods of diverting fish from such areas of danger as the intake piping of hydroelectric power generating turbines and pumping stations.

Abstract: A device for producing thrust has a variety of uses, such as pumping liquid, compressing or blowing air, or powering an aircraft. The device has a chamber with a sound driver located therein. The sound driver creates a compression standing wave in the chamber which will have at least one low pressure node and at least two high pressure peaks. An intake port extends through the chamber and is located adjacent the low pressure node for drawing in a fluid into the chamber. A discharge port extends through the chamber and is located adjacent the high pressure peak for discharging fluid from the chamber.

Abstract: A system is described that uses acoustic energy to position an object, which simplifies the application of forces in defined directions to the object and which enables the application of large forces to the object. The system includes transducers (21-24, FIG. 1) that direct separate acoustic beams (31-34) at the object (12), with the system constructed so the beams do not create standing wave patterns. A plurality of beams whose phases at the object are not closely controlled, are directed at different surface areas of the object so the beams do not substantially overlap at the object and create possible canceling effects. A very large force is applied to the bottom (124 FIG. 8) of an object lying in a gravity environment, by directing a plurality of beams (141-145) at the same area at the bottom of the object, and with the beams being controlled so they are substantially in phase at the object area. This plurality of beams can also replace one or all of the transducers (21-24, FIG.

Abstract: Ribbon made of long fibers has each of its ends separated into four bundles. The four bundles of each end carry the same four discrete indicia arranged in a different pattern. The bundles are inter-engaged so that the bundles of the same indicia lie together throughout the entire length of the splice. A splicing apparatus including clamps and guide loops holds the first set of bundles in place while the second set of bundles is inter-engaged therewith. Clamps are also provided to hold the ribbon ends in place.

Abstract: The invention provides apparatus for shaking structures such as fins in a fluid agitator, shaking tables, shaking screens, conveyors, or the walls of bins or hoppers. The apparatus is driven by a hydraulic driving system in which high pressure pulses are generated by repeatedly creating water hammer within a conduit. The high pressure pulses are directed to a chamber where they act against a wall of the chamber to periodically push on the structure. Preferably, the structure is spring-like so that after a high pressure pulse has passed the wall of the chamber is returned to its equilibrium position. In one embodiment of the invention a water hammer pressure pulse is directed into a reinforced hose in contact with a surface to be vibrated. The high pressure pulse causes the hose to expand and move the surface to be vibrated. Water hammer pulses are generated periodically so that the surface is maintained in continuous vibration.

Abstract: A method and apparatus are disclosed for generating intense acoustic pulses by means of the water hammer effect. The method involves generating a water hammer in a conduit by suddenly interrupting a high velocity flow of fluid through the conduit. The kinetic energy of the fluid flowing in the conduit is converted into a high pressure pulse which propagates along the conduit away from the point where the fluid flow was interrupted. The high pressure pulse deforms the wall of the conduit so as to radiate acoustic energy away from the conduit into a fluid medium surrounding the conduit. The relative amount of energy dissipated in the form of mass flow in the surrounding fluid and acoustic energy in the surrounding fluid can be adjusted by changing the characteristics of the conduit wall. The direction in which acoustic energy is radiated into the fluid medium surrounding the conduit can be set by making the conduit wall asymmetrical or by bending the conduit.

Abstract: An acoustic transducer mounting clamp for holding an acoustic transducer against a test surface utilizing fatigue resistant adhesive so as to facilitate the use of a gel couplant at the interface of the transducer and the test surface. The clamp has a base adhesively bondable to the test surface with the fatigue resistant adhesive; and a holder formed to the base and configured to hold the acoustic transducer in contact with the test surface with gel couplant disposed at the interface of the transducer and the test surface. The fatigue resistant adhesive maintains positioning of the acoustic transducer in contact with the test surface and the gel couplant facilitates transmission of acoustic energy from the test surface to the acoustic transducer.

Abstract: An acoustic/shock wave attenuating assembly comprised of porous screens forms an enclosure filled with a suitable pressure wave attenuating medium or material having fluid characteristics. This basic configuration can be suspended or held in place by a rigid structure. When the pressure attenuating medium is a liquid, the attenuating assembly is provided with a lining for containment. Multiple attenuating assemblies can be employed, with adjacent attenuating assemblies separated by a small gap. The pressure attenuating medium may be a liquid, a gas emulsion, an aqueous foam, or a gel (with or without entrained gas). Alternatively, solid particulates having bulk mechanical properties of a fluid may be employed as the pressure wave attenuating medium and may have an adhesive or the like resisting relative movement between particulates to simulate viscous effects.

Abstract: A method and system for mapping the acoustic near field of a stationary al symmetric structure are provided. The structure is subjected to a rotating excitation energy profile from a plurality of stationary excitation sites located radially around the structure. The acoustic near field of the structure due to the rotating excitation energy profile is measured along at least one line that conforms to a longitudinal surface of the structure. Mapping of the acoustic near field is complete when one rotation of the rotating excitation energy profile is complete.

Abstract: The present invention discloses a method for identifying the concentration of fuels or gases in air, particularly in the intake of motor vehicle motors, with ultrasound measurement, comprising the steps of conducting an air/vapor mixture whose concentration is to be identified through an ultrasound measuring section of known length, directing ultrasound through the mixture in the measuring section, determining the speed of sound through the air/vapor mixture; and identifying the concentration of the mixture on the basis of the speed of sound through the mixture in the measuring section.

Abstract: An apparatus (10) for implanting geophones (98) includes an implanting device (12) pivotally mounted on the end of a tractor (14) for movement from one predetermined location to another predetermined location for implanting a plurality of geophones (98). The implanting device (12) has a main support frame (16) supporting a vibratory frame (18) which receives a push tube (68) in sliding relation. The lower end of the push tube (68) accepts a geophone (98) for insertion therein. Downward movement of push tube (68) implants the geophone (98) as shown in FIG. 4. To assist in implanting the geophone (98), the vibratory frame (18) and the push tube (68) are vibrated for vibration of the lower end of the push tube (68) during implantation.

Abstract: A method for precisely adjusting the sensitivity of a polarized crystal hydrophone by applying a voltage signal to the hydrophone. Voltage pulses having selected characteristics are repeatedly applied to the crystal until it is determined that the sensitivity of the crystal has reached a desired level.

Abstract: An ultrasonic waveguide includes a fluid-tight thin-walled tube filled with a viscous, compressible fluid. One end of the tube is coupled to a transducer for transforming electrical energy into waves of ultrasonic energy which propagate the length of the tube. The other end of the tube has a window or refracting "shoe" for transmitting or refracting the propagating ultrasonic wave therethrough. The tube has a substantially constant cross section, preferably circular. The internal diameter of the preferred circular tube is in the millimeter regime, preferably from 0.25 to 1 mm. The wall material is preferably metal, plastic or metal/plastic composite.

Abstract: Methods and apparatus for sonically attracting bass fish to a desired location which entails propagating a sound into water constituting a habitat for fish, the propagated sound being an emulation of the sound made by a bass fish striking and eating a live bait species. In one embodiment of the invention, the propagated sound is originated at the location to which the fish are to be attracted by first recording the sound of bass fish striking and then consuming a live bait species at an underwater situs, and then propagating the recorded sound from a selected location.

Abstract: The present invention is drawn to a method of stabilizing the motion of a levitated object. The method involves continuously determining the motion of a levitated object, relative to a given point, and deriving the velocity of the object from the determined motion. A continuous, non-contact, corrective force is applied to the object in the opposite direction and proportional to the derived velocity.

Abstract: A method of selecting the ultrasonic transducers which are used in non destructive ultrasonic inspection apparatus consists of establishing under predetermined conditions the frequency spectra of the transducers under consideration, comparing these spectra with the frequency spectrum of a reference transducer obtained under the same predetermined conditions, and selecting only those transducers of which the frequency spectrum is substantially identical in form to that of the reference transducer.

Abstract: An acoustic/shock wave attenuating assembly comprised of porous screens forms an enclosure filled with a suitable pressure wave attenuating medium or material having fluid characteristics. This basic configuration can be suspended or held in place by a rigid structure. When the pressure attenuating medium is a liquid, the attenuating assembly is provided with a lining for containment. Multiple attenuating assemblies can be employed, with adjacent attenuating assemblies separated by a small gap. The pressure attenuating medium may be a liquid, a gas emulsion, an aqueous foam, or a gel (with or without entrained gas). Alternatively, solid particulates having bulk mechanical properties of a fluid may be employed as the pressure wave attenuating medium and may have an adhesive or the like resisting relative movement between particulates to simulate viscous effects.

Abstract: A portable device for accurately measuring acoustic velocities in solids. This portable hand-held device (100) uses dual receiving transducer tips (110, 112) to allow differential measurement of acoustic velocity in a solid. A body having a handle uses a transmitting transducer tip (108) to transmit acoustic energy to a solid. The first receiving transducer tip (110) is used in conjunction with a second receiving transducer tip (112) mounted on the body a fixed distance from the first (110). The device (100) uses the differences in the time of arrival of the wavefront at the first and second transducers to calculate the acoustic velocity in a given solid. This differential measurement method reduces acoustic velocity measurement inaccuracies.

Abstract: A method of driving a fluid by transmitting ultrasonic waves in the fluid, in which electrical signals applied to a transducer in the fluid are controlled to change the amplitude and duty ratio of tone burst waves so as to control the distribution of the ultrasonic driving force in the fluid, and the driving force itself.