56results about How to "Low speed of sound" patented technology

An electroacoustic transducer has reduced loss due to acoustic waves emitted in the transverse direction. For this purpose, a transducer comprises a central excitation area, inner edge areas flanking the central excitation area, outer edge areas flanking the inner edge areas, and areas of the busbar flanking the outer edge areas. The longitudinal speed of the areas can be set so that the excitation profile of a piston mode is obtained.

An elastic wave device includes a high acoustic velocity film configured such that a bulk wave propagates at a higher acoustic velocity than an elastic wave that propagates in a piezoelectric film, a low acoustic velocity film configured such that a bulk wave propagates at a lower acoustic velocity than a bulk wave that propagates in the piezoelectric film is laminated on the high acoustic velocity film, the piezoelectric film is laminated on the low acoustic velocity film, and an IDT electrode is laminated on one surface of the piezoelectric film. In an upper structure section, an energy concentration ratio of a main mode which is an elastic wave is not less than about 99.9% and an energy concentration ratio of a high order mode which is spurious is not more than about 99.5%.

Silica aerogels with improved properties are disclosed together with methods for synthesizing such aerogels. The improved properties include lower thermal conductivity (better insulating capacity), lower acoustic velocity, lower dielectric constant and improved ductility. Greater tunability of the refractive index can also be achieved. The silica aerogels are prepared by a sol-gel processing method that provides better control of the formation of aerogel structures. Generally speaking, the improvements arise from control of the synthesis to create a morphology of primary clusters and diverse-sized secondary clusters of dense silica aerogels separated by less densely packed regions. By providing a broader range of secondary clusters and/or pore sizes and loose connectivity between clusters, reductions can be achieved in thermal conductivity and flexural modulus.

The invention provides an ultrasonic non-destructive testing method for measuring circumference residual stress at root, the method is suitable for the non-destructive measurement of residual stress at the gear root. An LCR (critically refracted longitudinal) wave which is most sensitive to the stress is motivated through the combination of an ultrasonic stress measurement system, an ultrasonic transducer and a wedge block, and the residue stress at the region is precisely computed by using acoustic time difference of the LCR wave for detecting whether the stress is near to the root. The method is capable of accurately, fast and non-destructively detecting the residue stress value.

The invention relates to an argyrodite thermoelectric material, the chemical formula of which is Ag8Sn(1-x)NbxSe6, x=0-0.05. The preparation method of the argyrodite thermoelectric material is characterized by, with simple substances being raw materials, carrying out material blending according to stoichiometric ratio of the chemical formula; after vacuum packaging, melting reaction quenching and thermal treatment quenching, grinding ingots into powders; and carrying out vacuum high-temperature hot-pressure sintering, and after slow cooling, obtaining a block material, which is the argyrodite thermoelectric material. Compared with the prior art, the high-performance thermoelectric material, which is low in heat conduction and high in thermoelectric performance, is prepared, and the method for preparing the thermoelectric material, which is high in density, high in mechanical strength and high in thermoelectric performance, is explored; the thermoelectric material has very low lattice thermal conductivity (0.2-0.4 W/m.K) in a whole-temperature range; when the temperature is 900 K, thermoelectric peak of the thermoelectric material reaches 1.2; when the temperature is 300-850 K, the average thermoelectric figure of merit zTave of the thermoelectric material is infinity-0.8; and the argyrodite thermoelectric material is a potential thermoelectric material.

This patent relates to lined shaped explosive devices, in particular it relates to linear Shaped Charges (SC), more particularly it relates to a Fluted or Scalloped Linear Shaped Charge. The fluted linear SC, unlike a standard linear SC produces hydrodynamic penetration, higher jet velocities, higher mass jets and deeper penetration. The fluted linear device disclosed herein produces greater compression and convergence of the liner material because of the partial radial collapse of the concave flutes. Further, the fluted linear SC is equipped with a simultaneous initiation of the full length of the explosive driving the liner, providing smooth detonation wave front along the full length of the fluted linear liner.

The invention discloses an ultrasonic processing device, in particular to a high-speed rotary ultrasonic torsional processing device which comprises an output shaft and a transmission shaft. A rare-earth rod and tubular piezoelectric ceramic are mounted in an inner bore of the output shaft from inside to outside along an axial direction sequentially. An induction coil is wound on the output shaft, a coil former and an outer sleeve are arranged on the outer side of the transmission shaft, a closed coil storage chamber is formed by the coil former and the outer sleeve, and an excitation coil is disposed in the coil storage chamber. The ultrasonic torsional processing device which is manufactured on the basis of rare earth magnetostriction materials and piezoelectric ceramic materials is connected with a spindle of a machine, is subjected to two-dimensional ultrasonic mechanical vibration while driving a tool head to rotate at high speed, and thus, ultrasonic torsional processing of workpieces is achieved. Besides, the device realizes high-speed rotary ultrasonic torsional processing, ultrasonic frequency band is wide, ultrasonic energy is high, running state is stable, ultrasonic vibration amplitude can be regulated by changing magnetic field intensity and prepressure, and accordingly requirements of different processing precisions can be met.

The invention relates to an aerogel honeycomb sandwich board. The aerogel honeycomb sandwich board is composed of an upper-layer panel (3), a lower-layer panel (3) and a middle aerogel honeycomb core body. The aerogel honeycomb sandwich board is resistant to fire and flames, achieves heat insulation, and is good in sound insulation performance, high in strength and resistant to compression; the aerogel honeycomb sandwich board is good in anti-impact performance, low in mass and environmentally friendly, and has good application prospects.

The invention relates to a method for preparing a double-layer anti-reflection film for a silicon solar cell and belongs to the technical field of new energy materials. According to the method, a urethane acrylate modified SiO2 film is employed, the urethane acrylate has a urethane bond, the invention is characterized in that a plurality of hydrogen bonds can be formed between polymer molecular chains, the double-layer anti-reflection film has high wear resistance, adhesion, flexibility, high peel strength and excellent low-temperature resistance performance and the excellent optical performance and weather resistance of polyacrylate, a modified second layer anti-reflection film has excellent mechanical wear resistance and flexibility, and the breaking elongation is high. According to theinvention, the silver mirror reaction is used and the annealing treatment is combined, silver nanoparticles are prepared on the surface of a substrate to be a first layer anti-reflection film, the formation of the silver nanoparticles in random distribution is a result of the combined action of metal thermodynamics and kinetics, and when the rapid annealing is carried out, a silver film system acquires sufficient kinetic energy and tends to have nanoparticle structure with a small surface area.

The invention provides an ultrasonic nondestructive detection method for measuring high-speed railway wheel pair tread stress. The method is applied to the nondestructive measurement of wheel pair tread residual stress. Through the combination of an ultrasonic stress measurement system, an ultrasonic transducer and a wedge, an LCR wave which is most sensitive to the stress is excited. Through an acoustic time difference of the LCR wave with and without the stress near tread, the residual stress of an area is calculated. The residual stress can be accurately and rapidly detected in a nondestructive way.

An elastic boundary wave device employing an SH type elastic boundary wave having a large electromechanical coupling coefficient, a low propagation loss, a small power flow angle, a temperature coefficient of frequency TCF in an appropriate range, and a simple structure which can be produced through a simple process. A dielectric is deposited on one side of a piezoelectric and an IDT and a reflector are arranged as electrodes on the boundary of the piezoelectric and the dielectric, wherein the thickness of the electrodes is set such that the sound velocity of the SH type elastic boundary wave becomes lower than the sound velocity of a slow transverse wave propagating through the dielectric and the sound velocity of a slow transverse wave propagating through the piezoelectric.

The invention relates to a refrigerant compressor, comprising a compressor housing (1) that am be hermetically capsuled, and a compressor-motor unit (4) arranged in the housing interior (3) of the compressor housing (1), which is elastically mounted on an inner side of the compressor housing (1) by way of at least one spring element (5), wherein at least one damping element (9) made of an elastomer is provided, in order to damp the transmission of vibrations caused by the compressor-motor unit (4) to the compressor housing (1). The at least one damping element (9) is made of an elastomer tied is softer compared to polyamide (PA), polybutylene terephthalate (PBT), ethylene chlorotrifluoroethylene (ECTFE).

The invention discloses a wireless passive temperature sensing system for a main transformer cabinet of an electric locomotive. The wireless passive temperature sensing system comprises a surface acoustic wave temperature sensing unit, an antenna unit and an acquisition unit, the surface acoustic wave temperature sensing unit is mounted at a to-be-measured temperature in a main transformer cabinetof the electric locomotive, and is connected with the acquisition unit through the antenna unit; and the surface acoustic wave temperature sensing unit comprises a substrate, a piezoelectric substrate, an antenna module, an interdigital transducer and a reflecting grating. The piezoelectric substrate comprises a sound wave conduction substrate and a piezoelectric film positioned on the sound waveconduction substrate; the sound wave conduction substrate is located on the substrate, and the antenna module, the interdigital transducer and the reflecting grating are located on the piezoelectricfilm; and a sound absorption layer is laid on the surface of the piezoelectric film and used for absorbing bulk acoustic wave signals in the acoustic surface waves. The system has the advantages of high frequency, low time delay, high sound velocity, high reliability, high adaptability and the like.

Using a modified ultrasound device, crawling waves are applied to the liver over a range of shear wave frequencies. Dispersion measurements are obtained that reflect tissue viscosity and these correlate with the degree of steatosis. A device for the process has an actuator on either side of the ultrasound transducer to apply shear waves, which interfere to produce the crawling waves.

The invention relates to a small-hole type pulse tube thermoacoustic refrigerator, which includes a compressor, a hot-end heat exchanger, a regenerator and a cold-end heat exchanger. A compression cavity of the compressor, the hot-end heat exchanger, the regenerator and one end of the cold-end heat exchanger are connected in sequence, the other end of the cold-end heat exchanger is connected withone end of a resonant tube and one end of a pulse tube, the other end of the resonant tube is connected with a first gas reservoir, the other end of the pulse tube is connected with a second gas reservoir, and a small-hole valve is arranged between the pulse tube and the second gas reservoir. Compared with the prior art, according to the small-hole type pulse tube thermoacoustic refrigerator, low-temperature gas expanding for work is added through the pulse tube, and the small-hole valve at the hot-end of the pulse tube can adjust the refrigerating capacity; the resonant tube, under the low temperature, connected with the cold-end heat exchanger plays a phase-regulating role, and due to the low temperature, the acoustic work loss caused by viscous resistance and heat transfer is very small; and thus the efficiency of the thermoacoustic refrigerator can be improved through the structure of connecting the pulse tube and the small-hole valve to the cold-end heat exchanger of the thermoacoustic refrigerator.

There is provided a performance apparatus that is capable of reducing mechanical noise by a simple construction. Rotary picks are disposed in the vicinity of and in association with respective ends of a plurality of reeds, and four driving nails are formed integrally with outer peripheries of the rotary picks. A hook part is attached to the top of a plunger, and they make reciprocating motions together. The rotary pick is rotated by a driving force applied to the driving nail thereof from an engaging part formed by a lower end of the corresponding hook part. When the driving nail located symmetrically to the driving nail having received the driving force plucks the corresponding reed, the reed is sounded. The hook part is almost completely covered with a cushioning member formed of an elastic material such as rubber to absorb an impact that may occur when the driving nail of the rotary pick comes into contact with the hook part.

The invention provides a wide low frequency acoustic absorber with the folding space. The acoustic absorber includes a casing, a porous material layer and a winding body structure, wherein a top plateof the casing is a rigid perforation panel, the surface of the rigid perforation panel is provided with a through hole penetrating through an inner portion of the casing, a bottom plate of the casingis a rigid back plate, a sound absorbing cavity is formed inside the casing, the porous material layer and the winding body structure are disposed in the sound absorbing cavity, the porous material layer is disposed above the winding body structure, a gap is formed between the porous material layer and the winding body structure, the winding body structure includes two opposite rigid wall surfaces, opposite surfaces of the two rigid wall surfaces are provided with rigid plates which are perpendicular to the height direction of the casing in the height direction at equal intervals, the rigid plates on the two rigid wall surfaces are staggered, and the space between the rigid wall surfaces is divided into an S-shaped air passage. The acoustic absorber is advantaged in that the porous material layer and the winding body structure are integrated into one, and the relatively good noise abatement noise reduction effect is achieved.

A sonar dome having an acoustic array housed therein. A plurality of bubbles are generated within the fluid inside the sonar dome. The generated bubbles are of an amount and size to reduce the speed of sound within the sonar dome fluid. Reduction of the speed of sound within the sonar dome fluid effectively increases the aperture of the acoustic array. The bubbles can be generated from a gas source or electrolytically. Typically, each individual bubble is less than 0.01 mm in diameter to reduce bubble velocity in the fluid.