33 results about "Impedance tube" patented technology

The invention discloses a high-temperature sound absorption performance test device of a sound absorption material, comprising an impedance tube, a test piece cylinder disposed on one end of the impedance tube for arranging a test piece, a sound source arranged on the other end of the impedance tube, and microphones disposed on the inner wall of the impedance tube close to the test piece cylinder, wherein the microphones are connected with a computer through a spectrum analyzer and the sound source is connected with a signal generator through an amplifier. The invention is characterized in that a majority of the impedance tube is disposed in a heating furnace in the axial direction from the test piece cylinder; a small part of the impedance tube from the end connected with the sound source is disposed in a cooling device in the axial direction; a heat-insulation plate is disposed on the end of the furnace close to the cooling device; the other end of the furnace includes the test piece cylinder and can divide the furnace into two sections through a connector; a plurality of microphone jacks are provided on the middle section of the furnace; the microphones are disposed on the inner wall of the impedance tube through the jacks; a furnace chamber is arranged in the furnace; a heater is disposed in the furnace chamber; and a temperature controller with a temperature measuring thermocouple connected with the heater is disposed in the vicinity of the test piece.

A prediction apparatus for sound absorption and insulation performance of a multilayer material and a method are disclosed and relate to the field of testing of sound absorption and insulation performance of materials. The apparatus comprises an impedance tube with a built-in to-be tested single-layer material, a microphone group, a power amplifier, a data acquisition device, a computer and a loudspeaker. The method comprises: firstly testing the sound absorption and insulation performance of a single-layer material; testing the transfer function matrixes of other single-layer materials, and storing in a database; and utilizing the transfer function matrixes of the single-layer materials to calculate the sound absorption and insulation performance of the multi-layer material. According to the technical scheme, a four pole network theory is firstly utilized for testing the transfer function of the single-layer materials, and then the transfer function matrixes of the single-layer materials are utilized for directly obtaining the sound absorption coefficient and the transmission loss of the multi-layer material. The method is easy to realize and convenient to operate, also is high in testing precision, makes up insufficiency of impedance tube testing, and is widely applicable to noise optimization control of multiple fields.

The invention provides a calibration device and a calibration method for the equivalent self-noise acceleration spectrum level of a low-noise vector hydrophone. It is mainly composed of underwater acoustic tube, vacuum tube, electromagnetic shielding tube, vibration-damping base and upper cover. The noise self-spectrum measured by each vector hydrophone includes the self-noise spectrum and the environmental background noise spectrum, and the cross-correlation calculation of the noise signals of the two vector hydrophones can obtain the environmental background noise spectrum, and then through the known vector hydrophone The transfer function of the earphone can be calculated to obtain the equivalent self-noise acceleration spectrum level of the respective vector hydrophones. The present invention effectively reduces external vibration, electric, electromagnetic and acoustic interference, makes the background noise of the test environment extremely low, and thus better satisfies the calibration accuracy of the equivalent self-noise acceleration spectrum level parameters of the low-noise vector hydrophone It improves the evaluation effectiveness of the self-noise level of the low-noise vector hydrophone, and ensures the engineering application quality of the low-noise vector hydrophone.

The invention relates to a measuring system for material normal direction incidence acoustical absorption coefficient and acoustic impedance. The measuring system comprises a signal transmitter module, an impedance tube, a signal acquisition module, a signal processing module, a signal display module and a report generation module, wherein the signal transmitter module, the impedance tube and the signal acquisition module are connected in sequence, the signal processing module is respectively connected with the signal acquisition module, the signal display module and the report generation module, the signal transmitter module sends out single frequency sinusoidal acoustical signals to the impedance tube, the signal acquisition module acquires the acoustic pressure signal in the impedance tube in real time, and transmits to the signal processing module, the signal processing module displays the received real time acoustic pressure signal through the signal display module, the material normal direction incidence acoustical absorption coefficient and acoustic impedance are calculated through the adoption of a standing wave ratio method, finally the calculated result is generated through the report generation module, and a testing report is stored. Compared with the prior art, the measuring system has the advantages that the measuring process is straightforward, and the measuring accuracy and efficiency are high.

The invention relates to a material sampler for acoustic material detection, which is composed of a stander, a hydraulic jack, a guide pillar, a balancing plate, a spring, a cutting tool and a backing plate. The guide pillar is vertically and fixedly connected between the upper nog and the lower nog of the stander; the balancing plate is sleeved on the guide pillar; the spring is arranged on the guide pillar under the balancing plate; the hydraulic jack is fixedly arranged on the upper nog, the lower end of the jack being pressed on the balancing plate; the cutting tool, which is tubular, is connected under the balancing plate, the inner diameter of the cutting tool being equal to the inner diameter of the impedance tube of the material to be measured; and the backing plate is arranged on the lower nog. The material sampler can insure the conformity of the inner diameter of the material sample piece and the inner diameter of the impedance tube, the smoothness of the section and the conformity of the sample pieces so as to insure the accuracy of the detection for the performance parameters of the material, thereby reducing test cost and shortening time on testing.

A method of using a dual-port measurement system to measure acoustic impedance is used to measure an acoustic impedance Z of a tested object. The tested object includes an input end and an output end opposite to the input end. The dual-port measurement system comprises a first impedance tube and a second impedance tube. The first impedance tube includes a first inlet where a plane wave of a sound source is input, and a first outlet connected with the input end. The second impedance tube includes a second inlet connected with the output end, and a second outlet where the plane wave is output. The method uses the dual-port measurement system and a two-boundary method to obtain the acoustic impedances Z, whereby the dual-port measurement system is conveniently applied to various fields, such as the design of earphones, muffler tubes, sound absorption materials, and artificial ears.

The invention relates to a research method for conducting low-frequency noise processing by using COMSOL and resonant cavity models. The method includes the steps that firstly, resonant cavity modelsof different specifications are made; secondly, first detection groups are placed in B&K type 4206 impedance tubes respectively for sound reduction index testing, and second detection groups are placed in B&K type 4206 impedance tubes respectively for sound reduction index testing; thirdly, theoretical simulation of resonant cavity sound absorption is conducted by using COMSOL software until theoretical data fitted by the COMSOL software is basically consistent with experimental data in the second step; fourthly, expansion simulation of resonant cavity sound absorption continues to be conducted through a control variable method by using the COMSOL software, and finally an influence curve of film thickness and diameter on the sound absorption effect is determined. According to the film typeresonant cavity with adjustable parameters, the absorption frequency and absorption coefficient of the peak value are adjusted by changing the size of the models and the thickness of elastic films, theoretical simulation is conducted by using the COMSOL software, and specific absorption at a specific frequency is realized with the least space, the minimum material consumption and the lowest cost.

The present invention relates to an improvement method for a low noise structure and a sound absorbing structure of an indoor substation. The method visualizes and quantifies an external sound field of a power transformer through acoustic radiation characteristics analysis, combines acoustic radiation characteristics of the power transformer with feedback information between design departments toimprove and optimize an overall layout and the sound absorbing structure of the indoor substation, to reduce sound pressure level at the boundary of a noise sensitive area. Optimization of the overalllayout of the indoor substation includes adjusting position of a transformer vault away from the noise sensitive area, reducing height of a clearstory and changing orientation of the clearstory; Improvements of the sound absorbing structure include increasing depth of a cavity of the sound absorbing structure, attaching a metal film to inside of a foam metal sound absorbing panel, and changing position of some sound absorbing material. The method analyzes the acoustic radiation characteristics through impedance tube comparison test and establishing a 3D multiphysics coupling model. The improved sound absorbing structure can effectively improve overall sound absorption effect and reduce sound radiation level of the substation.

The invention discloses a backing-independent type acoustic impedance test method for an acoustic coating. An acoustic coating sample is placed at the intermediate position of the tube body of a water-filled impedance tube, and a liquid column of a certain height is ensured on both the upper surface and the lower surface of the acoustic coating sample. One end of the tube cavity of the water-filled impedance tube is internally provided with a projecting transducer. Two hydrophones are arranged in the liquid columns on the upper surface and the lower surface of the acoustic coating sample, respectively. The four hydrophones are respectively connected with a data acquisition instrument. The data acquisition instrument is connected with a measurement control computer. The projecting transducer is driven to launch a stabilized broadband white-noise signal. The data acquisition instrument acquires the acoustic pressures of the hydrophones at the same time and stores the acquired acoustic pressures as a data file. The height of the upper liquid column is changed, and then the data of the acoustic pressures are measured and stored again. After that, the stored data of the acoustic pressures are read, and then the input acoustic impedance and the transmission acoustic impedance of the acoustic coating sample are calculated according to a corresponding equation. According to the technical scheme of the invention, the low-and medium-frequency test accuracy is ensured independent of a backing. Meanwhile, the backing can be re-stuck without taking out the sample. Therefore, the measurement process is simplified, and the measurement efficiency is improved.

The invention discloses a camera module signal wiring mode. The camera module signal wiring mode is implemented in a camera module signal wire wring structure. The signal wire wiring structure comprises a substrate body, optical sensors and a plurality of components, wherein the substrate body is provided with a connection wire PAD, the optical sensors are located on the obverse of the substrate body, and the components are distributed on the obverse of the substrate body and located on the outer sides of the optical sensors. The signal wiring mode comprises the following steps that (1) a signal performs bypass parallel wiring; (2) smoothing is performed on the signal. Under the condition of limited design space, through the wiring mode of data signal wires in the optical sensors, the wiring lengths of a differential signal pair are matched, the transmission rates are equal, and better interference resistance is achieved. Because of the higher rates, the simpler signal wire connection and better differential impedance control over the signal by the wires, a camera module has the advantages of being stable in working, high in interference resistance and the like.

The invention relates to the technical field of sound insulation testing of an impedance tube, in particular to an acoustic measurement system with a tunable radial magnetic field loading device. Theacoustic measurement system comprises an impedance tube measurement system and a tunable radial magnetic field loading device. The tunable radial magnetic field loading device is composed of a circular-ring-shaped frame, a support frame, a coil unit, a lock nut, an insulating washer, and a DC power supply and is arranged outside the impedance tube measurement system; the magnetic field plane generated by the tunable radial magnetic field loading device is perpendicular to the impedance tube axis of the impedance tube measurement system, so that the circular-ring-shaped frame of the tunable radial magnetic field loading device and the impedance tube are in a concentric manner. Since the distance between the end of the coil unit and the outer surface of the impedance tube is controlled within 2 mm, the radial magnetic field is applied to a tested piece; and the tunable radial magnetic field loading device can move axially along the impedance tube, so that the radial magnetic field can beloaded at any position of the impedance tube.

The invention provides an adjustable test piece cylinder rear plate, and particularly relates to the field of feed production devices. The adjustable test piece cylinder rear plate comprises a bottomplate and a cylindrical impedance tube; the bottom plate is provided with a sealing column; the two sides of the sealing column are provided with a first clamping plate and a second clamping plate respectively, and the end parts of the first clamping plate and the second clamping plate are connected with the bottom plate; the sealing column is embedded into the impedance tube; and the side walls of the impedance tube is located between the first clamping plate and the sealing column and between the second clamping plate and the sealing column. According to the invention, the problems of air tightness and fixation caused by axially pushing the test piece cylinder rear plate can be solved.

The invention discloses a PCB impedance control method. The method comprises the steps: adding a region mark corresponding to a signal line region of a PCB light painting file in the PCB light painting file after the design of the PCB light painting file is completed, obtaining a marked PCB light painting file, and then transmitting the marked PCB light painting file and an impedance control requirement of the PCB light painting file to a board factory. Therefore, when the board factory carries out PCB resistance welding processing, distinguishing processing can be carried out according to the region mark and impedance control requirement, and the problem that the signal integrity cannot be guaranteed due to unqualified impedance matching caused by uneven resistance welding thickness of a signal line area due to the fact that the board factory processes the PCB according to a unified standard is solved. The invention further discloses a PCB impedance control device and equipment and a readable storage medium, which have the above beneficial effects.

The invention relates to an impedance tube sound insulation measurement technology, in particular to an axial magnetic field loading device with adjustable strength. The device is composed of a cylindrical pipe, a heat dissipation baffle, an enameled copper wire, a locking device, a piston rod, an adjustable lifting device and a direct-current power supply. The axial magnetic field loading device with the adjustable strength is connected through a tightening device, the cylindrical pipe and the impedance pipe are tightly connected, the problem of sound leakage in an impedance pipe measuring system is solved, and disassembly and assembly are convenient and fast. The axial magnetic field loading device with adjustable strength realizes loading of a uniform magnetic field, and the magnetic field strength is quantitatively controlled through input current. The heat dissipation baffle solves the problem that the sound insulation measurement precision is influenced because electric heat generated in a long-time experiment cannot be dissipated. An external adjustable uniform magnetic field test environment can be provided on the premise of ensuring the measurement precision.

A combustion system can include: a liner defining a combustion chamber; a casing covering the combustion chamber; a first tube disposed in the liner; a machined union disposed inside the casing and connected to the first tube; a second tube passing through the casing and connected to the machined union; a sensor housing disposed outside the casing and connected to the second tube; and an infinite tube connected to the sensor housing.