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213 results about "Auditory radiation" patented technology

The acoustic radiations or auditory radiations are structures found in the brain, in the ventral cochlear pathway, a part of the auditory system. Acoustic radiation arising in the medial geniculate nucleus and end in primary auditory cortex (transverse temporal gyri).

Power flow-boundary element model based elevated rail traffic vibratory-noise simulating and predicting method

The invention relates to a power flow-boundary element model based elevated rail traffic vibratory-noise simulating and predicting method. The power flow-boundary element model based elevated rail traffic vibratory-noise simulating and predicting method comprehensively considers bridge noise and steel-rail noise of the medium-frequency range (200-1000Hz) in elevated rail traffic, and is higher in noise prediction accuracy than that of a method only considering bridge noise or steel-rail noise. The method includes firstly establishing a rail- bridge system power flow model, calculating input power of bridges and vibration speed of steel rails when harmonic force units different in frequency act on the steel rails; secondly, calculating wheel-rail contact force spectrum under a wheel-rail-bridge coupling system through a wheel-rail combination roughness spectrum so as to obtain vibration states of the bridges and the steel rails under the action of random wheel-rail force; thirdly, respectively establishing an acoustic-radiation two-dimension finite-element-boundary element weak-coupling model for the bridges and the steel rails, and calculating vibration power and radiation sound field under the action of the harmonic force units at different frequencies; finally, acquiring practical vibration power by the power flow method and vibration power by the finite-element-boundary element model, scaling field-point sound pressure under the action of unit force to obtain the bridge noise, the steel-rail noise and the total noise thereof.
Owner:TONGJI UNIV

Piezoelectric ultrasonic transducer

The invention relates to a high-power radial vibration piezoelectric ultrasonic transducer suitable for liquid ultrasonic treatment under normal pressure and high pressure. The purpose of the present invention is to provide a high structural strength, high power density, which can generate uniform sound radiation in the radial direction of 360°, aiming at the defects of low structural strength and low power density of existing ultrasonic transducers, It is a high-power radial vibration piezoelectric ultrasonic transducer especially suitable for liquid ultrasonic treatment under normal pressure and high pressure. The invention comprises a piezoelectric ceramic disc, a prestressed annular cover plate, a cylinder body, an insulating vibration-isolating ring pad and an end cover, wherein a through hole is arranged on the piezoelectric ceramic disc, and the side of the piezoelectric ceramic disc and the prestressed annular cover plate The composite disk piezoelectric transducer is formed by radial compounding. Several composite disk piezoelectric transducer units whose geometric parameters are consistent with the radial resonance frequency are connected in electrical parallel, and are closely fixed on the inner wall of the cylinder at equal intervals. An insulating vibration-isolating ring pad is arranged between two adjacent composite disc piezoelectric transducer units.
Owner:ZHEJIANG NORMAL UNIVERSITY

Piezoelectric underwater sound transducer acoustic radiation mode measurement method and system

InactiveCN103743469AAddressed issue where reconstruction accuracy was often much lower than acoustic pressure reconstruction accuracyPrevent leakageSubsonic/sonic/ultrasonic wave measurementAuditory radiationSound pressure
The invention provides a piezoelectric underwater sound transducer acoustic radiation mode measurement method and system based on combination near-field acoustical holography. In the method, the combination near-field acoustical holography is utilized to reestablish sound field, sound pressure and radiation surface vibration velocity; on the basis of an acoustic radiation operator matrix obtained based on measurement data and with the sound field radiation theory being combined, the acoustic radiation power of a piezoelectric underwater sound transducer is expressed to be a positive definite quadric form; and positive definite and conjugate performance of the matrix are utilized to obtained an acoustic radiation mode of the structure. The system comprises a glass water tank, an industrial control computer with PXI bus, a transducer excitation module based on the PXI bus, a sound pressure and vibration velocity acquisition module and a three-dimensional motion platform. The method and system in the invention break the limitation that acoustic radiation mode in the current complex underwater structure can only be solved numerically, provide a new idea for research on the piezoelectric underwater sound transducer, and also provide basis for structure optimization of the piezoelectric underwater sound transducer.
Owner:XI AN JIAOTONG UNIV

A calculation method of electromagnetic vibration noise of electric machine

The invention discloses a method for calculating the electromagnetic vibration noise of a motor, which comprises the following steps: calculating the distribution of the electromagnetic force densityof the motor according to the operation condition of the motor, and calculating the static deformation and the natural frequency of the motor respectively; according to the distribution of the electromagnetic force density, the electromagnetic resultant force on the stator teeth of the motor is calculated, and the time-space harmonic of the electromagnetic resultant force is calculated. The frequency response function of the motor structure corresponding to each vibration mode is calculated according to the natural frequencies of each vibration mode corresponding to each spatial order of the electromagnetic force, and the transfer function of the motor mechanical structure is calculated according to the static deformation function and the frequency response function. The vibration displacement of the motor surface is calculated according to the time-space harmonics and the transfer function. The modal acoustic radiation efficiency of the motor housing is obtained, and the electromagnetic vibration noise of the motor is calculated according to the modal acoustic radiation efficiency and vibration displacement. In the process of analyzing the vibration and noise of the motor, the invention ensures that the calculation accuracy meets the precision requirement, and reduces the calculation amount to avoid consuming a large amount of calculation resources.
Owner:HUAZHONG UNIV OF SCI & TECH

Active control system and control method for radiation noise of vibration structure

The invention discloses an active control system and a control method for the radiation noise of a vibration structure. The control system is arranged on the vibration structure, K piezoelectric sensors obtain K external interference force reference signals which enable the vibration structure to vibrate and radiate noise, the K external interference force reference signals are input into a self-adapting feedforward controller, N control force signals are generated under the action of an algorithm and then are input into N piezoelectric actuation devices, new vibration acceleration distribution is generated in the vibration structure, K external interference forces are counteracted according to a secondary passage, an acoustic radiation mode amplitude value is generated according to a primary passage, an error sensor obtains the previous N stages of radiation mode amplitude value error signals with the strongest capability of radiating the noise during the vibration of the vibration structure and then inputs the previous N stages of radiation mode amplitude value error signals into the self-adapting feedforward controller, and a transverse filter weight coefficient is corrected by a filter weight coefficient iteration system so as to change the control force signals. The invention can obtain better control effect at intermediate frequency and low frequency, has simple structure and is easy to realize the miniaturization of the active control system.
Owner:JIANGSU UNIV
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