202 results about "Acoustical impedance" patented technology

The invention is directed biopsy site markers and methods of marking a biopsy site, so that the location of the biopsy cavity is readily visible by conventional imaging methods, particularly by ultrasonic imaging. The biopsy site markers of the invention have high ultrasound reflectivity, presenting a substantial acoustic signature from a small marker, so as to avoid obscuring diagnostic tissue features in subsequent imaging studies, and can be readily distinguished from biological features. The several disclosed embodiments of the biopsy site marker of the invention have a high contrast of acoustic impedance as placed in a tissue site, so as to efficiently reflect and scatter ultrasonic energy, and preferably include gas-filled internal pores. The markers may have a non-uniform surface contour to enhance the acoustic signature. The markers have a characteristic form which is recognizably artificial during medical imaging. The biopsy site marker may be accurately fixed to the biopsy site so as to resist migration from the biopsy cavity when a placement instrument is withdrawn, and when the marked tissue is subsequently moved or manipulated.

An acoustic wave resonator device comprising a resonant layer that comprises a series of side-by-side areas of first and second dielectric materials. In one embodiment the first dielectric material is a piezoelectric, in particular the first dielectric material can be a piezoelectric and the second dielectric material can be non-piezoelectric. In another embodiment, the first dielectric material is a piezoelectric of first polarity and the second dielectric material is a piezoelectric of opposite polarity or different polarity. Where needed, the resonant layer is supported on a reflector composed of series of layers of high acoustic impedance material(s) alternating with layers of low acoustic impedance material(s). For example, the reflector comprises AlN, Al2O3, Ta2O5, HfO2 or W as high impedance material and SiO2 as low impedance material.

The invention is a method of estimating, from data obtained by exploration of a zone of a heterogeneous medium, a model representative of a distribution, in the zone, of at least one physical quantity, the model being free of a presence of correlated noises that may be contained in the data which has application to determining the distribution in an underground zone of acoustic impedance, propagation velocities and permeabilities, etc. The method includes acquiring measurements giving information about physical characteristics of the zone; specifying a noise modelling operator which associates, with a model of each physical quantity, synthetic data that constitute a response of the model; selecting a noise modelling operator which associates a correlated noise with a noise-generating function belonging to a predetermined space of the noise-generating functions; specifying a norm or of a semi-norm in the data space; specifying a semi-norm in the space of the noise-generating functions; defining a cost function; and adjusting the model and of the noise-generating functions.

An acoustic matching structure is used to increase the power radiated from a transducing element with a higher impedance into a surrounding acoustic medium with a lower acoustic impedance. The acoustic matching structure consists of a thin, substantially planar cavity bounded by a two end walls and a side wall. The end walls of the cavity are formed by a blocking plate wall and a transducing element wall separated by a short distance (less than one quarter of the wavelength of acoustic waves in the surrounding medium at the operating frequency). The end walls and side wall bound a cavity with diameter approximately equal to half of the wavelength of acoustic waves in the surrounding medium. In operation, a transducing element generates acoustic oscillations in the fluid in the cavity. The transducing element may be an actuator which generates motion of an end wall in a direction perpendicular to the plane of the cavity to excite acoustic oscillations in the fluid in the cavity, and the cavity geometry and resonant amplification increase the amplitude of the resulting pressure oscillation. The cavity side wall or end walls contain at least one aperture positioned away from the center of the cavity to allow pressure waves to propagate into the surrounding acoustic medium.

It is an object of the present invention to provide an ultrasonic transducer, which is so configured as to reduce the variations in characteristics, thereby to enable the stabilization of the precision, as well as to enable the improvement of the durability, and the like, a method for manufacturing the ultrasonic transducer, and an ultrasonic flowmeter. In order to attain this object, in accordance with the present invention, the ultrasonic transducer is so configured as to include a piezoelectric element and an acoustic matching layer, wherein the acoustic matching layer is made of a dry gel of an inorganic oxide or an organic polymer, and a solid skeletal part of the dry gel has been rendered hydrophobic. With this configuration, it is possible to obtain the ultrasonic transducer having an acoustic matching layer 3 which is very lightweight and has a small acoustic impedance due to the solid skeletal part of the dry gel which has been rendered hydrophobic. Further, it is also possible to obtain the ultrasonic transducer which shows a narrow range of characteristic variations, and is stable due to the high homogeneity of the dry gel.

A device for determining the internal structure of a bone along a path directed into the bone (or other tissue) is disclosed. The device comprises a nozzle fluidically connected to a liquid reservoir for providing a liquid jet directed at the bone in the direction of the path; an ultrasonic transducer for generating ultrasonic waves through the liquid jet and for detecting echoes of the ultrasonic waves caused by changes in the acoustical impedance in the bone characterizing changes in the structure of the bone along the path; and an analyzer for interpreting the echoes into meaningful information relating to the location of the structural changes along the path.

A system and method for improving the efficiency and effectiveness of the transmission of acoustical energy to process fluids during substrate processing, such as cleaning or photoresist stripping. The invention utilizes a layered stack of materials to transmit acoustical energy from a source of acoustical energy to the process fluid. The material of which each layer is constructed is chosen so as to reduce the differences in acoustical impedance between consecutive layers of the stack, providing a more gradual transition, in terms of acoustical impedance, when acoustical energy is being transmitted from the source to the process fluid. In one aspect, the invention is a system comprising: a process chamber for receiving a process fluid; an acoustical energy source; and an acoustical stack having a first transmission layer and a second transmission layer that forms an acoustical energy pathway from the acoustical energy source to the process fluid in the process chamber.

The invention provides a sound absorption unit and a sound absorption device. The sound absorption unit comprises at least one quarter-wavelength tube bank body and at least one Helmholtz resonator row body which are arranged in a stacked mode in the preset direction; the quarter-wave tube bank body comprises a plurality of quarter-wave tubes arranged side by side, and each quarter-wave tube is provided with a first open end and a first closed end which are oppositely arranged; the Helmholtz resonator row body comprises a plurality of Helmholtz resonators arranged side by side, and each Helmholtz resonator is provided with a second open end and a second closed end which are oppositely arranged; the first open ends and the second open ends are adopted to jointly form a sound wave incident surface of the sound absorption unit; and in the preset frequency band, the overall acoustic impedance of the sound absorption unit is matched with the acoustic impedance of the air. The sound absorption unit can achieve a good sound absorption effect at a low frequency band, space can be saved, the preparation cost is reduced, and environmental pollution is reduced.

An ultrasonic transducer according to the present invention includes: a piezoelectric body 4 to set up ultrasonic vibrations; an acoustic matching layer 3 made of a material with a density of 50kg / m3 to 1,000 kg / m3;and an acoustic impedance of 2.5x103kg / m2 / s to 1.0x106kg / m2 / s ; a lower acoustic matching layer 9 provided between the piezoelectric body 4 and the acoustic matching layer 3; and a structure supporting member 6 that supports the lower acoustic matching layer 9 and the piezoelectric body 4 thereon and shields the piezoelectric body 4 from a fluid that propagates the ultrasonic vibrations. The ultrasonic transducer includes a protective portion, which contacts with at least a portion of a side surface of the acoustic matching layer 4. This protective portion is defined by a portion of the lower acoustic matching layer 9 and forms an integral part of the lower acoustic matching layer 9.