423 results about "Acoustic impedance" patented technology

Aspects of this disclosure relate to a bulk acoustic wave device that includes a multi-layer raised frame structure. The multi-layer raised frame structure includes a first raised frame layer positioned between a first electrode and a second electrode of the bulk acoustic wave device. The first raised frame layer has a lower acoustic impedance than the first electrode. The first raised frame layer and the second raised frame layer overlap in an active region of the bulk acoustic wave device. Related filters, multiplexers, packaged modules, wireless communication devices, and methods are disclosed.

The invention relates to an intelligent building damage detection method based on machine vision. The method comprises the following steps: multi-modal data acquisition; preprocessing and feature enhancement: processing the visual data and the acoustic data; damage detection: designing a material constitutive driven GAN architecture, calculating and generating stress distribution of a crack by a generator through a differentiable finite element analysis layer, performing L2 loss constraint on the stress distribution and an ABAQUS simulation result, evaluating image authenticity and physical consistency by a discriminator by adopting a double-branch structure, and outputting damage parameters in cooperation with a lightweight YOLOv8-Nano detection head; acoustics-vision depth fusion detection: aligning a potential space through a double-flow cross-modal encoder in combination with cross-modal contrast learning, and preferentially processing hidden damage by using a gating fusion unit for dynamically calculating a fusion weight through material acoustic impedance; when the visual detection confidence coefficient is smaller than a set threshold value, triggering frequency domain mutation detection and spatial positioning of the acoustic mode; and edge-cloud cooperative processing.

The invention relates to the technical field of nondestructive testing, and discloses a crack detection device and method for precise automobile parts. The method comprises the following steps: carrying out ultrasonic multi-dimensional pre-scanning and acoustic impedance abnormal region identification on a to-be-detected automobile part, carrying out influence range calculation and sensitive threshold classification based on abnormal region distribution data, and obtaining stress-acoustic response time sequence data through partition grabbing force distribution and stress loading; three-dimensional stress field reconstruction and stress concentration area identification are realized; performing dual-frequency stress modulation excitation and multi-physics field synchronous detection on the stress concentration area to obtain a multi-physics field response signal, performing multi-parameter fusion calculation and multi-scale wavelet decomposition of acoustic components on the multi-physics field response signal, and performing feature dimension splicing to obtain crack feature classification data; and calculating and generating a crack detection result based on feature similarity matching and extension prediction. The precision and reliability of crack detection of the automobile parts are remarkably improved, and the damage risk in the detection process is avoided.

The invention provides a machine tool machining parameter adjustment method and system, relates to the technical field of machine tool machining parameter adjustment, and aims to infer local acoustic impedance of a workpiece material in real time by emitting sound waves and receiving echo signals on the workpiece material in front of cutting of a cutter and extracting acoustic features. And when the local acoustic impedance is continuously higher than a preset normal reference value and exceeds a preset threshold value, determining that a local abnormal region exists, and generating an early warning signal. And before the tool makes contact with the local abnormal area, the machining parameters are adjusted in advance according to the early warning signal. And real-time feedback signals in the cutting process are continuously monitored, and the machining parameters are further adjusted based on the real-time feedback signals and the early warning signals. The problems that in the prior art, due to uneven local hardness of a workpiece material, a tool is unexpected to be abraded, and machining size deviation is accumulated can be effectively solved.

The invention discloses a wind turbine generator blade damage judgment method and detection system based on voiceprint detection, and belongs to the technical field of wind turbine generator blade detection. The damage judgment method comprises the following steps: acquiring environmental parameters of a wind power plant, and establishing a sound velocity correction model based on the environmental parameters; acquiring a blade resonance sound signal, and correcting the blade resonance sound signal based on the sound velocity correction model to obtain a blade resonance sound signal with a high signal-to-noise ratio; performing FFT spectrum analysis on the blade resonance sound signal with the high signal-to-noise ratio, identifying the peak position of the first three-order natural resonance frequency of the blade, and performing analysis to obtain the current modal frequency, damping ratio and sub-band energy distribution entropy value of the blade; historical baselines of the modal frequency, the damping ratio and the sub-band energy distribution entropy of the blade in the healthy state are obtained, and the modal frequency offset, the damping ratio change rate and the acoustic impedance spectrum entropy of the blade are obtained; and wind turbine generator blade damage determination is carried out by using a high-precision time difference detection technology.

The present invention relates to multi-stake underwater transducers and arrays for the generation and reception of sound waves in water. The invention provides the design and fabrication of compact piston-type underwater transducers of low-to-mid operating frequency made of piezoelectric single crystals without the need of any pre-stress mechanism. The invention uses a multi-stake pipe-like motor section made of piezoelectric single crystals of high transverse mode piezoelectric coefficients and low acoustic impedance, and small-diameter and light head mass(es). The present invention also discloses various means of increasing the bandwidth of the multi-stake underwater transducers as well as derivative transducers and arrays made of them, including compact 2D and 3D omni-directional transducers, planar, conforming and shaped arrays of various designs, high-density arrays and low-drop-down-ratio parametric arrays of either single or dual frequency bands.

The invention provides a switch cabinet contact temperature rise wireless sensing method and system based on surface acoustic wave resonance, and relates to the technical field of power system switch cabinet detection, and the method comprises the steps: calculating the real-time offset of a fundamental frequency and a third harmonic relative to a reference frequency, and obtaining the fundamental frequency offset and the third harmonic offset; in combination with the fundamental frequency offset and the equivalent acoustic impedance variable quantity of the oxide film, surface acoustic wave propagation path deformation caused by thermal expansion of the contact material is compensated by using a thermal-acoustic coupling partial differential equation, and the fundamental frequency net offset after temperature decoupling is obtained; sparse reconstruction is carried out on the temperature field of the contact area of the contact by adopting a compressed sensing algorithm, and three-dimensional temperature gradient distribution of the contact area of the contact is output; and inputting the three-dimensional temperature gradient distribution and historical time sequence data thereof into an intrinsic mode decomposition model for processing, and generating a dynamic self-adaptive early warning threshold value. The system has the advantages that passive, wireless, high-precision and full-space temperature rise monitoring is achieved, and intelligent operation and maintenance decision making of the switch cabinet is directly driven.

The invention discloses a cooperative control method and system for noise reduction and fire prevention of a transformer substation. The method comprises the following steps: determining the acoustic impedance mutation degree of an original composite board according to the frequency and amplitude distribution of target low-frequency noise of the transformer substation; when the acoustic impedance abrupt change degree exceeds an abrupt change threshold value, optimizing a first physical parameter of the original composite board; the heat flow density of the first composite board obtained through optimization is obtained, and if the heat flow density exceeds a fireproof threshold value, a second physical parameter of the first composite board is optimized; obtaining a noise penetration index of the target low-frequency-band noise in the second composite board obtained through optimization, and if the noise penetration index does not exceed a penetration threshold value, optimizing a third physical parameter of the second composite board; and determining final physical parameters corresponding to the acoustic-thermal performance balance point according to the acoustic impedance distribution and the thermal conductivity distribution of the third composite board obtained through optimization so as to adjust the structure of the third composite board. According to the invention, collaborative optimization of sound absorption frequency band characteristics and fireproof performance can be realized, and both noise reduction and fire prevention can reach an ideal state at the same time.

The invention relates to the technical field of material analysis, and discloses an intelligent raw material composition screening method and system based on a sound insulation material, and the method comprises the steps: collecting acoustic characteristic test data, microstructure data and chemical composition data of a candidate sound insulation material; performing frequency response curve decomposition on the acoustic characteristic test data to obtain a characteristic frequency band sound absorption coefficient, and constructing an acoustic impedance tensor of the sound insulation material to analyze the sound wave dissipation performance of the candidate sound insulation material; calculating the pore distribution entropy and connectivity index of the candidate sound insulation material to analyze the sound wave propagation retardation efficiency of the candidate sound insulation material; analyzing the molecular chain flexibility and interfacial compatibility of the candidate sound insulation material to evaluate the acoustic performance stability of the candidate sound insulation material for multi-component compounding; and screening a target material from the candidate sound insulation materials by using sound wave dissipation performance, sound wave propagation retardation efficiency and acoustic performance stability. The performance matching degree of the raw materials screened out of the sound insulation material in actual composite use can be improved.

The invention relates to the technical field of material corrosion and protection, discloses a TP2 copper corrosion behavior testing method based on temperature regulation and control, and aims to solve the problem that in the prior art, various physical and chemical parameters in the corrosion process are difficult to synchronously obtain under the same microscale, so that a local corrosion dynamics mechanism cannot be deeply revealed. The core of the system is a coaxial three-function composite probe integrated with thermal, acoustic and electrochemical sensing units, and the coaxial three-function composite probe is matched with a synchronous laser heating module and a multi-physical field synchronous control system. During testing, the probe scans on the surface of a sample, local thermal disturbance is applied to each pixel point, and the interface temperature, acoustic impedance and corrosion rate data of the point are synchronously collected. According to the invention, through high integration in structure and accurate synchronization in time, the space mismatch error of multi-source measurement is eradicated, and multi-physical field distribution images which are accurately corresponding to each other can be obtained in situ and losslessly.

The invention discloses a single-hole pressure adjusting method, device and equipment for a water curtain test of an underground water-sealed cave depot and a storage medium, and relates to the technical field of geological engineering.The method comprises the steps that firstly, a rock mass acoustic impedance spectrum is collected, intrinsic mode decomposition is carried out to extract geologic feature components, and the rock mass acoustic impedance spectrum is obtained; processing the target pressure value, the current pressure value and the geologic feature component by using a pressure-opening coupling model based on acoustic feature extraction, time sequence dynamic analysis and physical constraint decoding to obtain a reference valve opening; then, a water curtain hole valve is adjusted according to the reference valve opening degree, and the pressure change acceleration is monitored in real time; calculating an opening compensation increment and a damping attenuation coefficient based on the pressure change acceleration, and further generating a target valve opening; and finally, the valve is adjusted to the target opening degree, so that the water curtain hole reaches the target pressure value. According to the invention, high-precision self-adaptive adjustment of the pressure of a single water curtain hole can be realized in the water curtain test of the underground water-sealed cave depot.

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.

The invention belongs to the technical field of acoustics, and particularly relates to an index type open-pore rigid plate internal vector sound field calculation method, program and equipment and a storage medium. According to a Webster equation satisfied by a simple harmonic plane sound source excitation sound pressure field, circular piston radiation acoustic impedance on an infinite baffle plate is adopted to represent radiation impedance at an opening of an exponential open pore, a sound field analytical solution of any depth in the open pore of the exponential open pore rigid plate is constructed, system calculation is carried out in combination with sound source conditions, and a sound field of any depth in the open pore of the exponential open pore rigid plate is obtained. Therefore, sound field quantities such as internal accurate sound pressure and vibration velocity of the exponential type open-pore rigid plate under the vertical incidence condition can be quickly solved, and sound field distribution conditions under different section change rules and different open-pore rigid plate sizes can be calculated. According to the method, the calculation complexity is low, the influence problem caused by sound field changes under the non-free field condition can be solved, and the calculation stability and reliability under the complex boundary condition are ensured.

The invention relates to the technical field of aero-engine nondestructive testing, and discloses a method for detecting defects and thickness of a surface coating of an aero-engine blade. The invention designs a novel acoustic impedance sensor special for a blade coating, the novel acoustic impedance sensor comprises a plurality of independently controlled transduction units, each transduction unit has multi-band detection capability, main resonant frequencies of different transduction units are configured in a differentiated manner, and during detection, the novel acoustic impedance sensor is coupled to the surface of a blade; the material state is reversely deduced by measuring the energy absorption spectrum of broadband sound waves in the coating, and the blade surface coating defect and thickness detection is achieved.

The invention belongs to the technical field of turbofan engine silencing acoustic liner design, and particularly relates to a turbofan engine silencing acoustic liner acoustic impedance determination method comprising the following steps: 1, calculating silencing acoustic liner acoustic resistance rn influenced by high sound intensity; 2, calculating the acoustic resistance rg of the silencing acoustic liner influenced by the tangential flow; 3, considering the influence of high sound intensity and tangential flow, and according to the relative magnitude of the sound particle speed amplitude Vo and the main flow speed Vg in the small hole, calculating the sound resistance r of the sound reduction acoustic liner in a segmented manner; 4, calculating a noise reduction acoustic liner tail end correction coefficient delta under the comprehensive influence of tangential flow and high sound intensity; step 5, considering the comprehensive influence of tangential flow and high sound intensity, and calculating the acoustic reactance x of the silencing acoustic liner; and step 6, integrating the acoustic resistance r and the acoustic resistance x of the silencing acoustic liner, and calculating the acoustic resistance z of the silencing acoustic liner.

Embodiments of the invention relate to an acoustic resonator device for excitation of bulk acoustic waves (BAW) with enhanced power handling capabilities. The acoustic resonator device has a composite piezoelectrical platelet which comprises a first piezoelectrical layer and a second piezoelectric layer with the same or similar acoustic impedance but with opposite phase wave excitation for a given wave polarization. The dimensions of the composite piezoelectrical platelet for a given static capacitance can hence be increased, while maintaining a wide bandwidth of the acoustic resonator device.

The invention belongs to the technical field of transducer matching layers, and particularly relates to a high-frequency underwater acoustic transducer matching layer structure for deep sea detection, which comprises an integrated gradient functional material layer, the acoustic impedance of the gradient functional material layer is in gradient change along the sound wave propagation direction, and a pressure self-adaptive microstructure is embedded in the material layer. In the invention, aiming at the problem that a pressure-resistant structure is not designed in a contrast patent, acoustic performance drift caused by deformation under the high pressure of 60MPa is prevented, the negative Poisson's ratio honeycomb substrate expands but does not shrink under the hydrostatic pressure of 60MPa and resists compression deformation, and the pressure response type silicone oil filled in the microsphere system has the advantages that the density is increased along with the increase of the pressure, and the sound velocity change is automatically compensated; and the acoustic impedance fluctuation is relatively small, so that 6000-meter deep-sea long-term operation is supported, the problem of performance degradation of the existing transducer in deep sea is solved, and meanwhile, the micron-sized displacement risk of a filling cone in a contrast patent is avoided.

The present disclosure provides a thin-layer low-frequency underwater sound insulation metamaterial, including two cover plates and a sound insulation layer. The sound insulation layer is composed of sound insulation components arranged in an array periodically. The sound insulation components each include a sound insulation unit and four connecting units. The sound insulation unit is of a hollow rectangular column structure. The four connecting units are arranged at four corners of the sound insulation unit. Every two adjacent sound insulation units are connected through the connecting units. A long side wall of the sound insulation unit and the corresponding cover plate have an included angle of 0-90°. The metamaterial can obtain a smaller equivalent acoustic impedance in propagation direction of acoustic waves, and compared with a sound insulation material of a square honeycomb structure with the same thickness, the metamaterial has greatly improved sound insulation performance.

A scroll compressor and a refrigeration apparatus. The scroll compressor comprises a stationary scroll (320) and a partition plate (330), wherein an exhaust port (321) and an exhaust channel (322) are provided in an upper end of the stationary scroll (320), and the exhaust port (321) is arranged at the bottom of the exhaust channel (322); the partition plate (330) is connected to the stationary scroll (320) and covers the stationary scroll (320), and the partition plate (330) is provided with a silencing hole (331); the silencing hole (331) is in communication with the exhaust channel (322); and the equivalent diameter of the silencing hole (331) is D, and the diameter of the exhaust channel (322) is D2, which satisfies D2 / D2 2≤0.6. By means of limiting the diameter ratio of the silencing hole (331) to the exhaust channel (322), the flow area of the silencing hole (331) is made relatively small, so that on one hand, the acoustic impedance of a cross section can be increased, thereby reducing the propagation of high-frequency noises (with relatively short wavelengths), and thus a good effect on reducing the high-frequency noises is achieved.

The invention aims to provide an ultrasonic transducer capable of continuously and stably working in a high-temperature and high-pressure extreme environment, and belongs to the technical field of ultrasonic nondestructive testing, the ultrasonic transducer comprises a packaging matching layer, a piezoelectric layer, an electrode layer and a backing layer, the packaging matching layer can have the effects of high temperature resistance, high pressure resistance and heat dissipation so as to match acoustic impedance, and the piezoelectric layer is arranged on the backing layer. Therefore, the acoustic performance of the transducer is improved. The piezoelectric layer can keep excellent piezoelectric performance in a high-temperature environment. The electrode layer and the back lining layer can achieve a good heat dissipation effect, and the service life is prolonged. The method has a wide application prospect in the field of ultrasonic nondestructive testing in an extreme environment.

The present disclosure relates to a bulk acoustic wave (BAW) device with electrostatic discharge (ESD) protection. The disclosed BAW device includes a substrate (106), an ESD protection layer (106) over the substrate (106), a first bottom reflector (109-1) over the ESD protection layer (108), a first bottom electrode (112-1) over the first bottom reflector (109-1), a first top electrode (118-1) vertically aligned with the first bottom electrode (112-1), and a piezoelectric layer (116C) vertically between the first bottom electrode (112-1) and the first top electrode (118-1). Herein, the ESD protection layer (108) is electrically insulating and eligible to achieve at least a 400 V breakdown voltage with a 200 nm thickness. The first bottom reflector (109-1) includes a stack of alternating high acoustic impedance conductive layers (120A-E) and low acoustic impedance conductive layers (120A-E). The first bottom electrode (112-1) is electrically connected to the first bottom reflector (109-1). A breakdown voltage of the piezoelectric layer (116C) is no more than the breakdown voltage of the ESD protection layer (108).

The invention provides lightweight sound-absorbing mute cotton and a preparation method thereof, the lightweight sound-absorbing mute cotton is of a bionic gradient structure and is divided into three layers, the bottom layer dissipates high-frequency sound waves, the middle layer optimizes intermediate-frequency resonance, and the upper layer enhances low-frequency sound wave scattering. The preparation method comprises the following steps: respectively preparing bottom-layer slurry, middle-layer slurry and upper-layer slurry; pre-cooling the bottom of a mold, and carrying out synchronous three-layer co-injection molding on the three kinds of slurry: carrying out one-way freezing to form a longitudinal gradient aperture; freezing and drying to obtain a three-layer gradient structure material; immersing in a graphene oxide quantum dot ethanol solution for vacuum treatment; heating, adding ascorbic acid, keeping for 2 hours, and applying 0.5% pre-strain to the material; photo-thermal curing is performed; and performing hot-pressing shaping to obtain the product. The gradient structure design is adopted, and the aperture, the fiber distribution and the filler type are regulated and controlled, so that acoustic impedance gradient change is realized, sound wave reflection is reduced, and the sound absorption efficiency is improved.

The invention provides a three-dimensional noise reduction structure system drainage pipe design method, and belongs to the technical field of building drainage pipes. Discretization analysis is carried out on a three-layer structure of a spiral flow guide structure PVC pipe inner wall, an asymmetric butyl rubber damping interlayer and gradient density foamed aluminum by establishing a three-dimensional noise reduction model; and constructing a vibration transfer matrix and a noise reduction key point matrix. A spiral flow guide structure is optimized through hydraulic calculation, thickness distribution of a rubber damping layer is determined through acoustic impedance testing, foamed aluminum porosity gradient design is carried out, and a small-section noise reduction cross-correlation index is introduced to evaluate the synergistic effect of adjacent structures. The optimal material ratio is solved through a three-dimensional noise reduction optimization equation set, the noise reduction effect is predicted in combination with an acoustic response deep learning model, standardized module design is finally formed through miniaturized sample piece test verification and parameter correction, and organic unification of full-band noise reduction and modular design of the drainage pipe is achieved.

The invention discloses an ultrasonic double-wave detection and monitoring method and an ultrasonic double-wave transducer, and the ultrasonic double-wave transducer comprises a piezoelectric element which is used for exciting a longitudinal wave signal and a transverse wave signal at the same time under the excitation of a single electric pulse; the backing layer is positioned on the back surface of the piezoelectric element and is used for absorbing longitudinal wave energy radiated to the back surface by the piezoelectric element; the matching layer is arranged between the piezoelectric element and the tested workpiece and is used for acoustic impedance matching; the electrical connection device is used for connecting an external excitation generator and receiving equipment; and the metal shell is used for packaging the piezoelectric element, the backing layer, the matching layer and the electrical connection device and is provided with a structure for applying pre-tightening force. According to the invention, dual-mode excitation is realized through a single piezoelectric plate structure, and the efficiency, precision and reliability of dual-wave ultrasonic detection are improved.

The invention discloses a high-frequency transformer sound pressure calculation method, and relates to the technical field of circuits, and the method comprises the steps: obtaining a microstructure parameter of a gap beryllium copper reed to generate a microstructure feature vector; on the basis of the microstructure feature vector, calculating magnetostriction strain of microstructure regulation and control to determine coupling field distribution description of microstructure regulation and control magnetostriction; on the basis of the coupling field distribution description, performing finite element grid division on an air domain around the high-frequency transformer to generate an air domain finite element grid; enabling a gap beryllium copper reed to be equivalent to an acoustic impedance boundary condition, and defining a pseudo-density variable in an air domain finite element grid to determine the optimal sound wave propagation path tracking in the air domain; and calculating the sound pressure of the high-frequency transformer based on the tracked sound wave propagation path. According to the method, the feature vectors are generated by obtaining the structure parameters, the magnetostrictive strain is accurately calculated, grid division is optimized, the calculation precision is improved based on boundary condition processing and multi-link cooperation, and a reliable basis is provided for product design.

An acoustic resonator is provided that includes a piezoelectric layer, an interdigital transducer (IDT) including a plurality of interleaved fingers on the piezoelectric layer, a substrate, and an acoustic reflector between the piezoelectric layer and the substrate. The acoustic reflector that is on the piezoelectric layer includes alternating first layers of first materials and second layers of second materials. A first acoustic impedance of the first materials is different from a second acoustic impedance of the second materials. A ratio of a pitch of the IDT over a thickness of the piezoelectric layer is less than 10. A first thickness of at least one of the first layers is larger than a quarter of a first wavelength λ1. λ1 is an acoustic wavelength of a shear bulk wave in the at least one of the first layers at a resonance frequency of the transversely-excited bulk acoustic resonator.

The invention relates to the field of noise reduction control of power equipment, in particular to a corrugated composite silencer used for reducing low-frequency noise in a transformer. The corrugated composite silencer structurally comprises a corrugated expansion cavity, a high-frequency sound absorption layer, a backflow cavity, an internal perforated plate and a hard wall, the corrugated expansion cavity is a main body part of the silencer and is directly connected with the inlet side and the outlet side of the silencer; the high-frequency sound absorption layer is attached to the outer side of the corrugated expansion cavity and is separated from the corrugated expansion cavity by an internal perforated plate; the backflow cavity is located on the outer side of the high-frequency sound absorption layer and is separated from the high-frequency sound absorption layer through a hard wall and an internal perforated plate. Wherein the corrugated expansion cavity adopts a corrugated wall surface and is used for improving the equivalent acoustic impedance of the silencer structure and improving the low and medium frequency noise reduction effect of the silencer; the high-frequency sound absorption layer is filled with high-frequency sound absorption materials such as glass fiber cotton so as to improve the medium-high frequency noise reduction capacity of the structure. And the backflow cavity is used for specifically absorbing noise with specific frequency at low and medium frequencies. The corrugated wall surface is combined with the backflow cavity, the corrugated composite silencer structure for low-frequency noise reduction in the transformer is designed, and the actual noise reduction requirements of most transformers can be met.

The invention relates to the technical field of sound absorption and noise reduction, in particular to an anti-impact sound absorption and noise reduction lattice superstructure which comprises an array formed by connecting a plurality of sound absorption cavities, each sound absorption cavity is a truncated octahedron formed by a plurality of panels, and the panels comprise eight regular hexagonal panels and six quadrilateral panels. The two adjacent edges of every two adjacent panels are connected through a hollow truss, and a micro hole is formed in the center of each panel. According to the adjustable Helmholtz resonator, the hollow structure is introduced, stress concentration at truss nodes is effectively reduced, the panels are arranged between the adjacent trusses, an internal air phase is constructed through the micropore design, the sound absorption frequency band of the structure is widened, the sound impedance of the structure can be adjusted through the micropores, and therefore the multiple complete adjustable Helmholtz resonators are formed; when the frequency of incident sound waves is close to the inherent frequency of the resonator, the air columns in the micropores generate strong vibration, sound energy is consumed due to the thermal viscosity effect, and the sound absorption and noise reduction structure can have good sound absorption and energy absorption effects while having good mechanical performance.

The invention relates to the technical field of building materials, in particular to a bio-based multifunctional sound insulation wallboard and a preparation method thereof. The wallboard comprises a sound absorption layer and a sound insulation layer. The sound absorption layer is cooperatively constructed by an inactivated mycelium three-dimensional porous framework and microalgae biomass, and the sound insulation layer is a high-density complex formed by compounding bio-based raw materials such as wood fiber, straw, recycled paper pulp and shell filler. And the two are combined through a biological-physical mechanical interlocking interface formed by hypha growth, extension and embedding to form a natural acoustic gradient structure from porous low acoustic impedance to compact high acoustic impedance. According to the preparation method, an in-situ growth process of mycelium culture and microalgae coating is embedded into a hot-pressing process, a three-dimensional anchoring network is formed by actively embedding mycelia into the sound insulation layer, the microalgae permeates into pores and is subjected to hot pressing to generate biomacromolecules for bonding and filling, a porous structure is synchronously constructed by a one-step method, and firm interlayer bonding is realized. The wallboard has excellent broadband acoustic performance, stable bonding strength and low-carbon and environment-friendly benefits.

The invention discloses a preparation method of a silicon dioxide-epoxy resin composite material, the acoustic impedance of the composite material is controlled by adjusting the volume fraction of the silicon dioxide-epoxy resin composite material, an ultrasonic transducer prepared by utilizing the composite material and a preparation process thereof, and an imaging system designed by utilizing the ultrasonic transducer. By designing the matching layer and the backing layer with specific acoustic impedance, seamless fusion of ultrasonic imaging and photoacoustic imaging is realized, the transducer has ultrahigh sensitivity, broadband characteristic and high optical transparency, shows bimodal imaging capability of high contrast and high resolution, and solves the problem that a traditional transparent ultrasonic transducer is insufficient in acoustic performance.