690 results about "Frequency sound" patented technology

The invention belongs to the technical field of vehicle state detection and early warning, and particularly relates to a vehicle state monitoring and early warning method and system.The monitoring and early warning method comprises the steps that a sensor obtains real-time data, an anomaly detection algorithm is applied, and an abnormal event is marked; calculating an information priority according to the abnormal severity and the driving scene, and distributing the information priority to a high-priority queue; multi-mode early warning is generated, and high-frequency sound and vibration are used during high-speed driving; extracting a voice prompt, and generating voice waveform data through a voice synthesis module; voice input of a driver is recognized, intention is analyzed, and abnormal information feedback is provided; according to the scene and the abnormal state, interactive output is optimized, and detailed information is displayed during low-speed congestion; dynamically adjusting the interface of the instrument panel, and amplifying the key area in case of abnormal severity; and integrating the image data and the voice data, generating a multi-mode signal, and transmitting the multi-mode signal after rendering processing. The vehicle abnormal information can be timely and accurately transmitted to a driver, and the driving safety is effectively improved.

The invention discloses a foam cement-based sound absorption material with an adjustable and controllable pore structure and a preparation method of the foam cement-based sound absorption material, and belongs to the technical field of building functional materials. Aiming at the problems of insufficient pore structure regulation and control, limited sound absorption performance and high cost of a traditional cement-based sound absorption material, P.O42.5R Portland cement is used as a basis, a physical-chemical synergistic foaming method and a three-stage gradient temperature control freeze-drying process are combined through the synergistic effect of a composite foaming agent, a microporous structure regulator and a composite pore forming agent, and the sound absorption material is prepared. Precise regulation and control of pores from the nm level to the mm level are achieved, and an interconnected pore channel network with the high open porosity is formed. The density of the obtained material is 200-1000 kg / m, the porosity is 60-90%, the aperture coverage range is 2 nm-6 mm, the open porosity is 70-85%, the 28d compressive strength is 1.83-14.56 MPa, the average sound absorption coefficient in the frequency range of 250-2000 Hz is 0.12-0.62, and the noise reduction coefficient is 0.14-0.64. The composite material has the characteristics of adjustable pore structure, light weight, high strength, broadband sound absorption, low cost and good durability, and is suitable for the noise control fields of building walls, traffic facilities and the like.

The invention provides a broadband sound absorption structure suitable for undercarriage cabin door noise reduction and a design method, and belongs to the field of aircraft noise reduction. The sound absorption structure comprises a plurality of perforated plate type Helmholtz cavity unit cells and a plurality of embedded pipe type Helmholtz cavity unit cells. In the perforated plate type unit cells, one or more first through holes are formed in the perforated plate. And in the embedded pipe type unit cells, the embedded pipes penetrate through the perforated holes in the perforated plates and extend into the cavities. Cavities of the two single cells face the same direction, and the perforated plate forms a curved surface conformal with an undercarriage cabin door. The effective length of the neck of the perforated plate is increased by using the embedded pipe, the low-frequency sound absorption performance is improved, the sound absorption performance and the sound absorption bandwidth of the middle-frequency band are improved by using the perforated plate type Helmholtz cavity, meanwhile, the curved surface conformal design is highly matched with the special-shaped cabin door structure, and the sound absorption performance is improved. The low-frequency and medium-frequency sound absorption performance can be guaranteed, and meanwhile the light and thin requirements of an aircraft can be met; and a pure passive mechanical structure is adopted, so that the control complexity and stability risks of an active noise reduction system can be avoided.

The invention relates to an intelligent bedside instrument for relieving insomnia with assistance of sound waves. The intelligent bedside instrument comprises a sound wave adjusting module, a sound wave resonance relaxing system, a sleep state monitoring module and a personalized feedback system, the sound wave adjusting module sends specific sound waves to the sleep environment, and the sleep environment is automatically optimized based on sleep stage data monitored in real time by adjusting the frequency and intensity of the sound waves. The sound wave resonance relaxing system emits low-frequency sound waves with specific frequency into a bed head or a pillow according to the sleep state of a user, and the low-frequency sound waves are transmitted to the head and the body of the user through the resonance effect and used for relaxing tense muscles, stimulating deep nerves and helping the user to quickly relax and sleep. Through sound wave adjustment, resonance relaxation, accurate sleep state monitoring and a personalized feedback system, the sleep quality of a user is effectively improved, the user is helped to quickly enter deep sleep from a light sleep state, external interference is avoided, a sleep adjustment scheme is continuously optimized through intelligent analysis, and personalized requirements are met.

The invention discloses a frequency mixing sound demodulator based on a curled structure and a use method thereof in the acoustics field, the demodulator is used for separating frequency mixing sound mixed by a plurality of sound waves with preset frequencies according to respective frequencies, and the demodulator comprises an air waveguide for transmitting the sound waves, and blocking structures arranged on two sides of the air waveguide for blocking the sound waves from penetrating, and a plurality of curled structures that capture corresponding preset frequency sound waves; curled structures are arranged in the barrier structure on at least one side of the air waveguide at intervals, one end of each curled structure is open, and the other side is closed; a plurality of cross beams for blocking penetration of sound waves are arranged in each curled structure, and an internal channel of each curled structure is divided into different lengths to serve as different acoustic resonant cavities so as to capture the sound waves with different frequencies; the closed end of each curled structure is a detection end of each preset frequency sound wave. The invention solves the problem that the existing method is difficult to instantly separate the frequency mixing sound signal and carry out information transmission.

The invention discloses a leakage monitoring method of a sealing connection structure for hydrogen conveying, and relates to the field of gas conveying and storage monitoring, and the method comprises the steps: S1, arranging an annular negative pressure sampling cavity to collect multi-modal data, and calculating the angle section suspiciousness; s2, applying thermal pulse and sweep frequency sound wave excitation, and collecting a response signal to generate a thermoacoustic leakage score; s3, environment compensation and multi-sensor fusion are carried out to obtain an angle section hydrogen concentration time sequence; s4, obtaining an inversion flux based on the comprehensive response and sparse-smooth inversion to realize leakage positioning; and S5, calculating a risk score and performing graded alarming according to a threshold value. Multi-point detection units are arranged in the circumferential direction of the sealing connection structure, signal fusion is adopted, full-coverage leakage monitoring and high-precision positioning of the sealing structure are achieved, emergency measures are automatically triggered in combination with risk grading, and the discovery timeliness and safety are improved.

The invention discloses an underwater passive positioning method combining multi-scale feature extraction and transfer learning. The underwater passive positioning method comprises the following steps: acquiring sound wave data of a sound source to be positioned in a simulation environment; performing feature extraction on the to-be-positioned sound source sound wave data to obtain sound source sound wave features; the sound source sound wave features are input into a positioning prediction model, the sound source distance and the sound source depth are predicted, the positioning prediction model is obtained through training of a training set, and the training set is waveform data of different frequency sound pressures; and domain migration is carried out on the sound source sound wave positioning problem in the simulation environment to a real sea test environment, and underwater sound source positioning is carried out. According to the invention, the acoustic diversity and dynamic change characteristics of the marine environment can be comprehensively captured, and the adaptability of the model to the real environment is improved.

The invention relates to a ventilation and noise reduction structure and device and electric equipment, the ventilation and noise reduction structure comprises a first shell and a second shell, the first shell is enclosed to form a ventilation channel, the second shell is sleeved outside the first shell, a cavity is formed by the second shell and the first shell, and the ventilation channel is communicated with the second shell. The first shell is provided with at least one through hole which is communicated with the ventilation channel and the cavity, and the through hole is used for reducing noise; therefore, an effective resonance noise reduction structure is formed through the cavity and the through holes, the resonator structure is combined with the ventilation channel, under the condition that ventilation is guaranteed, a sound insulation wide spectrum can be effectively formed, noise in a wide frequency range is blocked, and therefore the wide-spectrum sound insulation effect on sound waves of different frequencies is achieved while the ventilation effect is guaranteed.

The invention discloses a multi-channel audio calibration method, system and device and a storage medium, and relates to the technical field of audio, and the method comprises the steps: collecting and separating a main sound channel signal and a bass sound channel signal in a multi-channel audio signal; detecting time delay between a main sound channel and a bass sound channel based on a phase correlation algorithm, and performing adaptive delay compensation; the state change of the audio signal is monitored in real time, and before or when a signal switching event is detected, gradient gain envelope is applied to the bass sound channel signal, so that the signal amplitude gradually changes to a target value according to a preset nonlinear curve; a sonic boom event is analyzed and identified based on multi-dimensional characteristics, a self-adaptive amplitude limiter with a prospective processing capability is started for suppression, and harmonic distortion compensation and phase correction are carried out on a processed signal, so that the problems of signal asynchronization caused by low-frequency output delay of an audio system in the prior art, and the system reliability is improved are solved. Therefore, the low-frequency sound quality and the system stability are improved.

The invention discloses a method for realizing ocean sound field prediction based on a pre-training optimized physical information neural network, which comprises the following steps of: pre-training: constructing a hypothetical ocean environment, generating simulation data in a sound pressure envelope form by using an acoustic numerical calculation tool, and pre-training the physical information neural network to learn a physical rule of sound field propagation; fine tuning: adjusting an energy scale factor according to the proportion of the sound pressure amplitude of the actual measurement point to the sound pressure amplitude of the pre-trained environment, and performing fine tuning by using the envelope amplitude data of the actual measurement sound field for the pre-trained physical information neural network to obtain an ocean sound field prediction model through a pre-training-fine tuning dual-stage strategy; and ocean sound field prediction: according to the ocean sound field prediction model, obtaining a target position envelope from the to-be-predicted range, and then converting the target position envelope into a sound pressure result to realize ocean sound field prediction. The method can improve the high-frequency sound field modeling precision and training efficiency, and can be widely applied to the fields of ocean sound field modeling, sound source localization and environment inversion.

The invention provides a robust optimization method and device for a low-frequency sound absorption metamaterial, and relates to the technical field of punching, and the method comprises the steps: obtaining a response function of a target metamaterial through employing a linear one-dimensional rheological model; determining a target coupling region by using an imaginary part of a transfer function zero point corresponding to the response function or a size relationship between inherent loss and radiation loss as a coupling criterion, and determining a closed coupling region where a preset parameter point is located as an initial robust region; the target coupling region comprises a closed coupling region; the preset parameter point meets the one-dimensional frequency domain response of the target metamaterial; and determining the size of the initial robust region by using the Lexberg measure of the Euclidean space, and optimizing the robust region by maximizing the Lexberg measure of the initial robust region in the Euclidean space to obtain a target robust region. According to the method, the maximum robust region in the parameter space is found through maximum measurement, so that the response characteristics of the viscoelastic damping material under the actual working condition can be accurately described.

The invention provides a big data-based material detection method and system, relates to the field of material quality detection, and solves the technical problems of insufficient detection precision and poor supply chain quality control linkage in an existing material detection method. The method comprises the following steps: transmitting sweep-frequency sound waves to warehouse-in materials of a peripheral warehouse by using a sound wave transmitting device; collecting vibration velocity spectrum data and sound pressure gradient data of the warehouse-in material after the warehouse-in material receives the frequency sweep sound wave; according to the vibration velocity spectrum data and the sound pressure gradient data, calculating a defect index of the warehouse-in material; and when the defect index is greater than a preset threshold value, marking the warehousing material as a defective material, sending a traceability detection instruction to a previous node warehouse, and starting a grading detection process of the previous node warehouse. The method and the device are used for warehousing detection, quality traceability and full-chain management and control processes of the materials in the supply chain.

The invention belongs to the technical field of low-frequency sound absorption, and discloses a micro-perforated plate composite gradient spiral pipe sound absorption device and method.The micro-perforated plate composite gradient spiral pipe sound absorption device comprises a variable cross-section spiral pipe, and the diameter of the inlet end of the variable cross-section spiral pipe is larger than that of the outlet end of the variable cross-section spiral pipe; a plurality of MPP plates are mounted in the variable-cross-section spiral pipe, one MPP plate is embedded into the inlet end of the variable-cross-section spiral pipe, and the other MPP plates are sequentially embedded into the variable-cross-section spiral pipe at equal intervals, so that a multi-stage MPP plate composite sound absorption structure is formed; and the cross-section pipe diameter of the variable cross-section spiral pipe is linearly reduced from the inlet end of the variable cross-section spiral pipe to the outlet end of the variable cross-section spiral pipe. Through the gradient design of the variable cross-section spiral tube integrated micro-perforated plate, low-frequency broadband efficient sound absorption is realized in a compact space, the problem of heavy structure caused by dependence on a deep and large back cavity in the traditional technology is avoided, the limitation of narrow sound absorption frequency band is overcome, and the sound absorption device is particularly suitable for being applied to occasions with limited spaces and has wide application prospects. And low-frequency performance and broadband characteristics are considered in a limited space.

The invention discloses a low-frequency sound propagation loss forecasting method suitable for a polar region sea area, and the method comprises the steps: building a two-dimensional ice layer model of a forecast sea area according to remote sensing data based on the setting that sea ice of the polar region sea area is a uniform elastic medium; calculating hydrological conditions of the ocean sound channel of the polar sea area; establishing a forecast sea area two-dimensional seabed model according to the seabed topography sediment database; an under-ice sound field model is constructed based on a three-dimensional cylindrical coordinate system, sound pressure from unit intensity sound sources with different sizes and depths to a receiving point in a forecast sea area is calculated through a frequency domain finite element method in combination with a PML technology, and sound propagation loss of a needed position is obtained through calculation. According to the method, the application limitation of traditional ray and normal wave theories under complex boundary conditions is broken through through a finite element method, a synergistic effect mechanism of actual ice layer parameter space change, submarine topography fluctuation and sound velocity profile gradient characteristics is systematically analyzed, and sound field modeling is more accurately carried out on different ice layers and submarine topographies in the Chukong sea region all year round; the influence of sound wave propagation is simulated.

The invention discloses a low-frequency sound absorption device for a wind tunnel corner flow deflector, and the device comprises a housing which is internally provided with a low-frequency sound absorber and an impedance matching layer. The low-frequency sound absorber comprises a Helmholtz resonance cavity, a sealing ring and an elastic support, the Helmholtz resonance cavity is distributed in the sealing ring in a square lattice or rectangular lattice mode, and the sealing ring is connected with the shell through the elastic support; the impedance matching layer comprises a porous material layer, an air matching layer and a gradual change section cavity, the porous material layer is connected with the surface, closest to sound wave incidence, of the shell, the air matching layer is located between the porous material layer and the gradual change section cavity, and the sectional area of the gradual change section cavity is gradually increased in the sound wave incidence direction. The thickness of the low-frequency sound absorption device does not exceed 650 mm, the low-frequency sound absorption device is high in aerodynamic noise absorption coefficient at the low frequency band of 50-200 Hz, has excellent high-temperature resistance, can stably operate in the working environment of 150 DEG C or above, and meets the strict working conditions of a wind tunnel laboratory.

The invention discloses intelligent sound equipment, and relates to the technical field of sound equipment, the intelligent sound equipment comprises a shell, a first partition plate, a second partition plate, a high-frequency loudspeaker, a full-frequency loudspeaker and a radiation unit, and the shell is provided with an accommodating cavity; the first partition plate and the second partition plate are arranged in the containing cavity at intervals so as to divide the containing cavity into a high-frequency cavity, an intermediate-frequency cavity and a low-frequency cavity which are sequentially arranged, the size of the high-frequency cavity is smaller than that of the intermediate-frequency cavity, the size of the intermediate-frequency cavity is smaller than that of the low-frequency cavity, and the high-frequency loudspeaker is arranged in the high-frequency cavity. The full-frequency loudspeaker is arranged in the intermediate-frequency cavity, the second partition plate is provided with a frequency division unit communicated with the intermediate-frequency cavity and the low-frequency cavity, the frequency division unit is used for scattering and absorbing medium-high frequency sound waves and keeping propagation of low-frequency sound waves, and the radiation unit is arranged in the low-frequency cavity; the radiation unit is used for receiving low-frequency sound waves which are emitted by the full-frequency loudspeaker and are transmitted to the low-frequency cavity through the frequency division unit so as to enhance low-frequency response.

The invention discloses an energy storage safety early warning system of a smart power grid, and relates to the technical field of smart power grids, the system comprises a parameter acquisition module, a data preprocessing module, a fusion analysis module, a dynamic threshold adjustment module and an early warning output module; multi-mode physical parameters of vibration frequency, sound characteristics and electromagnetic field change of the energy storage equipment are introduced, traditional temperature and electric quantity parameters are combined, comprehensive and deep monitoring of the operation state of the equipment is achieved, the analysis mode of multi-parameter fusion not only enriches data dimensions, but also improves the reliability of the equipment. Meanwhile, by means of the artificial intelligence algorithm, the early warning threshold value can be dynamically adjusted according to equipment operation data and environment data which are collected in real time, so that the method can be more flexibly adapted to changes of the equipment operation state, and the comprehensive and accurate equipment state evaluation and early warning mechanism can be used for improving the accuracy and reliability of equipment state evaluation. And a powerful guarantee is provided for safe operation of an intelligent power grid.

The present disclosure related to a method of using high frequency sound waves directed toward an acoustically active particle. The high frequency sound waves may be configured to enlarge the acoustically active particle and oscillate the acoustically active particle, thereby facilitating extravasation of an agent to a tissue compartment of a region of interest.

The invention relates to the technical field of micron-sized jet flow and uniform atomization, in particular to a monodisperse uniform fog drop device and an atomization spray head spray hole array arrangement method, and the monodisperse uniform fog drop device comprises a driving source, a liquid supply device and a spray head; the spray head is a monodisperse atomizing spray head, the driving source is an ultrasonic signal generating system, the liquid supply device supplies constant-pressure fluid to the spray head, and the spray head forms monodisperse spray under the driving of high-frequency sound waves of the ultrasonic signal generating system; the spraying hole array arrangement method of the atomizing nozzle comprises the following steps of: setting smaller spraying hole spacing in small deformation areas close to the center of the spraying hole plate and constraint ends on two sides of the spraying hole plate; a large safety distance is arranged in a large deformation area between the restraining end of the spray orifice plate and the center of the spray orifice plate, so that intersection caused by jet flow intersection is prevented. According to the device and the arrangement method, the problems of mutual interference and the like between large-scale array jet flows are solved; the controllability of the size and the speed of the monodisperse atomized liquid drops can be effectively improved, so that macro micro liquid drops with uniform size and concentrated speed are generated.

A method and a system for improving the low-frequency sound reproduction of an audio signal, the sound reproduction being performed by an audio system comprising at least one loudspeaker. The system includes a low-frequency sound enhancement module with filters for separating an input audio signal into a high-frequency signal and a low-frequency signal. The system is configured to implement a first audio processing of the low-frequency signal to obtain a low-frequency output signal and a second audio processing of the high-frequency signal to obtain a high-frequency output signal. The low-frequency sound enhancement module includes, for the first processing of the low-frequency signal, a module for increasing the dynamic range of the low-frequency signal, which is parameterised as a function of at least one transient part of the low-frequency signal.

The invention belongs to the field of wood modification, and relates to plastic wood, a preparation method thereof and application of the plastic wood in preparation of acoustic materials. The technical problems that in the prior art, wood is insufficient in flexibility and plasticity, the preparation process is complex, and the cost is high are solved. The invention provides a preparation method of plastic wood, which comprises the following steps: removing lignin from log to obtain pretreated wood; the wood is put into an epoxy soybean acrylate solution to be soaked, the concentration of epoxy soybean acrylate ranges from 10 wt% to 40 wt%, and the soaked wood is obtained; and the flexibility and plasticity of the obtained plastic wood are improved, and the dimensional stability is improved. Meanwhile, aiming at the technical problems that in the prior art, an acoustic material is too large in dead weight and difficult to update, low-frequency sound wave dissipation capacity is poor, the environment is polluted, and human health is harmed, the invention further provides a preparation method of the acoustic material, and the defects of a traditional sound insulation material are overcome while the performance requirement is met. The invention further provides application of the plastic wood and the acoustic material.

The invention relates to the technical field of sound absorption composite materials, in particular to a porous composite material capable of enhancing sound absorption performance and a preparation method and application of the porous composite material capable of enhancing the sound absorption performance. And high-efficiency sound absorption can be realized in the full frequency band of 100Hz-6000Hz. Especially in the low-frequency band of 200Hz-1000Hz, the sound absorption coefficient is increased by 20%-50% compared with that of a traditional porous material with similar thickness and weight, and the problem that the traditional material is insufficient in low-frequency sound absorption is solved.

The invention discloses a focusing type acoustic streaming heat dissipation device facing a chip. The device belongs to the crossing field of ultrasonic technology and heat dissipation technology and is composed of a piezoelectric stack, an acoustic lens, a splitter plate, a base, a supporting rod, a copper electrode and the like. According to the device, geometric parameter configuration of the splitter plate, the piezoelectric stack and the acoustic lens is optimized, and a double-piezoelectric-plate stacked structure is adopted to enhance the ultrasonic resonance effect; high-frequency alternating voltage is applied to the copper electrodes at the two ends of the piezoelectric stack, high-frequency sound waves are excited through the inverse piezoelectric effect, and after the sound waves are focused through the sound lens, a gradient sound pressure field is formed in a cavity formed by the splitter plate and the piezoelectric stack; air molecules are driven to move directionally based on the acoustic streaming effect, so that air flow at an air inlet is accelerated by sound pressure to form high-flow-rate focusing jet flow at an air outlet, and targeted forced convection heat dissipation of a chip heat source is realized. According to the device, the ultrasonic technology and the heat dissipation technology are combined, the whole device is simple in structure, free of moving parts and low in noise, and various heat dissipation requirements can be met in an array mode.

The invention provides a preparation method of a perforated UHPC board fireproof, high-temperature-resistant, waterproof and moisture-proof strong sound absorption composite material, and belongs to the technical field of UHPC boards. An optimal perforation parameter combination is calculated through a two-layer nested optimization function system; preparing UHPC slurry and adding polypropylene fibers for toughening; carrying out pouring molding by adopting a vacuum vibration process and carrying out steam curing; performing precise perforation according to the optimized parameters; the basalt fiber cloth is adhered to the back surface to enhance the low and medium frequency sound absorption performance; the surface is coated with nano silicon dioxide sol to form a waterproof and moistureproof protection layer; performing acoustic performance evaluation to ensure that the medium-frequency sound absorption coefficient is greater than or equal to 0.7 and the high frequency is greater than or A fireproof performance test is carried out to ensure that an A-grade fireproof grade and a 2-hour fire endurance are reached; finally, performing a waterproof and moisture-proof performance test to ensure the water absorption rate lt; and 50 times of damp-heat circulation can be resisted. The optimal parameters comprise common perforation UHPC: the hole diameter is 5mm, the distance between the circle centers of two holes is 12mm, and the perforation rate is 13%; the method realizes organic unification of sound absorption performance and special environment adaptability.

The invention relates to the technical field of sound production instruments, and provides a patch type buzzer, which adopts a double-layer circuit board structure, a second circuit board is provided with a conversion element, and the conversion element and an electric appliance element on the second circuit board form a direct current-alternating current conversion circuit for converting direct current into alternating current. When the second circuit board and the first power connection board are stacked up and down, the conversion element is limited on the conversion element receding groove, so that the second circuit board abuts against the first power connection board, and when the buzzer adopts single-frequency sound production, the size of the buzzer can be designed to be smaller, and the buzzer can be more compact. When the volume of the buzzer is the same as that of a buzzer in the prior art, the internal space of the buzzer is relatively increased due to the fact that the second circuit board abuts against the first power connection board, and multi-frequency sound can be made.

The invention discloses a large-scale fish resource detection method based on multi-frequency sound waves and an AI algorithm. The method comprises the following steps: correcting an original echo signal into a signal under a standard environment characteristic in combination with the environment characteristic; extracting and normalizing frequency spectrum characteristics and time sequence distribution information of the echo signals; obtaining frequency response characteristic data of fish types and associating spatial position information of the fish types; obtaining a fish swarm proportion through three-dimensional point cloud clustering analysis; identifying a fish school abnormal behavior type and an area range, and formulating a fish school abnormal intervention strategy; predicting a time point, an area range, an abnormality type and a reason of the abnormal behavior of the fish school in a future time period; and in combination with Mahalanobis distance and fish school behavior prediction, evaluating the effect of the fish school abnormal intervention strategy, and dynamically adjusting the fish school abnormal intervention strategy. According to the invention, the precision and efficiency of fish resource detection can be improved, the requirements of dynamic monitoring and precise management of fish schools in a large-range water area are met, and the healthy and sustainable development of a water area ecological system is further promoted.

The invention discloses a low-frequency light and thin sound insulation structure, a thickness calculation method and application, the low-frequency light and thin sound insulation structure comprises a bottom plate, a partition plate, a perforated plate and a porous material which are sequentially arranged from bottom to top, the partition plate is of a concentric-square-shaped structure, and the porous material is located in a mounting cavity defined by the bottom plate, the partition plate and the perforated plate; the bottom plate, the partition plate, the perforated plate and the porous material are combined together to achieve low-frequency sound insulation. The sound insulation characteristics of thin plate resonance, the porous material and the micro-perforated plate + cavity are effectively combined together, according to the environment sound insulation requirement, double-side low-frequency sound insulation is achieved, the sound insulation performance of the thin plate side is better than that of the perforated plate side, the sound insulation amount is higher than 30 dB, and the low-frequency sound insulation performance is excellent.

The invention relates to the technical field of material performance detection, and discloses a non-destructive evaluation method and system for the strength of microorganism mineralized river sand, and the method comprises the following steps: applying a sweep frequency sound wave excitation signal to a microorganism mineralized river sand standard sample model; performing penetration simulation operation on the microorganism mineralized river sand standard sample model according to the sweep frequency sound wave excitation signal; extracting mineralization specific characteristic parameters corresponding to the sample model through the penetration response signal; according to the mineralization specificity characteristic parameters, constructing a biological cementation index of microorganism mineralization, and according to the biological cementation index, analyzing the compressive strength of the microorganism mineralization river sand standard sample model; constructing a destructive calibration curve of the microorganism mineralized river sand standard sample model; the target compressive strength of the to-be-tested sample model is analyzed through the destructive calibration curve, and the strength non-destructiveness of the microorganism river sand corresponding to the to-be-tested sample model is analyzed based on the target compressive strength. According to the method, the accuracy of non-destructive evaluation of the strength of the microorganism mineralized river sand can be improved.

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 discloses a voice privacy protection method and device based on high-frequency sound signal mixing, and the method comprises the steps: firstly collecting user voice data, and constructing a personalized user corpus; then a user customizes a scene demand, selects a text theme synthesized by speech, and carries out user corpus extension; then, the user selects a noise theme related to the interference from the selected text theme according to the specific living situation where the user is located, and voice segments are randomly extracted from a user corpus corresponding to the noise theme to generate interference noise; modulating the interference noise to a preset frequency band interval; and finally, when it is detected that the user is talking, the controller sends a modulated interference signal to an interference unit, and the interference unit injects the interference signal into a nearby microphone. The method has practicability and security, can effectively protect user privacy, and can resist attacks of various denoising technologies such as speech enhancement and blind source separation.