71 results about "Nonlinear acoustics" patented technology

A method of processing an audio signal in a nonlinear acoustic system to reduce distortion in corresponding regenerated audio signals. A first nonlinear processing method includes producing a modeled representation of signal demodulation through a propagation medium, applying an inversion to the modeled representation of signal demodulation, and processing an audio signal using the inverted, modeled signal demodulation representation. A second nonlinear processing method includes applying an inversion to a signal demodulation function, producing a modeled representation of the inverted signal demodulation function, and processing an audio signal using the modeled representation of the inverted signal demodulation function. The processed audio signal is then modulated using an ultrasonic carrier signal, and projected through a propagation medium using an acoustic transducer.

The present invention discloses a non-linear ultrasonic on-line monitoring metal material strain changing method, belonging to the metal material fatigue damaging analysis technology field. A probe is arranged at the middle portion of a piece to be tested, two ends of the piece to be tested are fixed, a weight is hung at the middle portion of the piece to be tested, and the gravity of the weight is employed to generate stretching for the piece to be tested to generate fatigue. A support frame for monitoring strain on line is made on the piece to be tested, and the support frame is internally provided with an ultrasonic energy transducer. The high energy pulse signal output end of a nonlinear acoustics detection device performs interaction with the ultrasonic transducer through 50 Ohm impedance matching and a duplexer to receive reflected supersonic wave signals through reflection of the piece to be tested. The non-linear ultrasonic on-line monitoring metal material strain changing method can realize online monitoring of the metal materials to estimate in-service workpiece mechanics status under external load long-term effect so as to reduce the engineering project risk caused by metal workpiece fracture failure, solve defects of high cost and complex operation of a current device and have business application and popularization values.

The invention discloses a method and device for detecting fatigue damage of a cable.The method includes the steps that an excitation sensor and a receiving sensor are installed on the cable; the excitation sensor is controlled to generate excitation guide waves, and the receiving sensor acquires a time domain waveform graph of passing signals; according to the time domain waveform graph, amplitude values corresponding to base frequency and doubled frequency components in the passing signals are acquired; non-linear acoustic parameters are obtained according to the amplitude values, and the fatigue damage state of the cable is determined according to the non-linear acoustic parameters.The device is used for achieving the method and comprises a signal generation module, a signal receiving module and a signal processing module.Detection on micro-damage of the cable is achieved by acquiring the non-linear acoustic parameters caused by the micro-damage of the cable, and the advantages of being high in detection precision, facilitating detection and the like are achieved.

The invention belongs to the field of non-linear acoustics, and particularly relates to a control method for bubble motion chaotization in a sound field based on parameter perturbation. The method comprises the steps: obtaining a radius and a pulsation speed of a three-dimension autonomous bubble at any time; measuring resonant frequency of the bubble, and estimating the size of a balance radius of the bubble; conducting the parameter perturbation on a bubble vibration system; and building a perturbation control parameter database under different balance radiuses of the bubble. According to the control method, a dynamics model of bubble motion under the parameter perturbation is built, the control method for the bubble motion chaotization based on the parameter perturbation is provided, limitation of a high-intensity and additionally incentive sound filed sound pressure level achieving the bubble motion chaotization is overcome, and requirements on devices such as underwater acoustic emission transducer and a power amplifier are reduced. Real-time picking of bubble vibration responses is avoided. The method improves the chaotization effect of the system, and achieves the optimal control on bubbles of the different radiuses.

The invention relates to a phase control method of acoustic energy conversion under the nonlinear mutual action of three acoustic wavetrains. The phase control method of acoustic energy conversion under the nonlinear mutual action of the three acoustic wavetrains is characterized in that the three acoustic wavetrains are sent in a water medium space position, x=0, in a concurrent mode and in the same direction, the three acoustic wavetrains satisfy the relation that omega1= omega3+ / - omega2, the omega1, the omega2 and the omega3 respectively represent the angular frequency of the first acoustic wavetrain, the angular frequency of the second acoustic wavetrain and the angular frequency of the third acoustic wavetrain, the transmitting sound power of the second acoustic wavetrain and the ransmitting sound power of the third acoustic wavetrain are large, an obvious nonlinear acoustic effect can be triggered in the water medium, and the three acoustic wavetrains have nonlinear mutual action. The control over acoustic energy is achieved by adjusting the phase phi i(x) (i=1, 2 and 3) among the three acoustic wavetrains and the phase relation phi 0(x), wherein the phase relation phi 0(x) = phi 3(x) - phi 2(x). According to the restrictive relation that the phase phi i(x) in the position x depends on the acoustic wave phase phi 0(x) in the initial position x=0, effective control over the space position where acoustic energy conversion occurs and the rising and decreasing effect of the acoustic energy is achieved only by adjusting the phase relation phi 0(0) under the initial condition.

An improved hearing protection device intended to be inserted into an external auditory meatus of a user, having a housing structure, a passive tuning element, and a passive, nonlinear acoustic filter. The tuning element and the acoustic filter may be supported in series by the housing structure. The tuning element may be or include a diaphragm, a resonator, or both. The housing structure may support a diaphragm of the tuning element at its circumference, and may provide cavities on both sides of the diaphragm. In some embodiments electronic components are included in the hearing protection device to counteract insertion loss provided by the passive element, and restore natural hearing for low to moderate sound pressure levels, Communications devices may also be incorporated into the hearing protection device. The combination of a simple, low cost amplifier circuit, passive tuning element and nonlinear acoustic filter of some embodiments of the present invention achieve a low cost yet sophisticated ability to react to impulse noise without the need for a microprocessor or complex electronics. Furthermore, the configuration reduces power consumption and, therefore, increases service life or decreases battery size / capacity, and results in low electronic self-noise allowing the user to maintain situational awareness,

Gauss-Rees waveform utilization in identifying an object, includes: directing a primary acoustic waveform at the object to produce a nonlinear acoustic effect; receiving a secondary wavelet produced by the nonlinear effect; and processing the received secondary wavelet in identifying the object. The object is identified by composition, image, and preferably both. The object can be concealed in a container, underground, under water, or otherwise.

An acoustic diode includes a phononic crystal medium, a nonlinear acoustic medium, a aluminum tubes contain the phononic crystal medium and the nonlinear acoustic medium. The phononic crystal medium is fabricated by alternately laminating a water layers and a glass layers in a periodic manner.