71 results about "Nonlinear acoustics" patented technology

The invention relates to a method for identifying plate defect and damage based on a nonlinear acoustics and time reversal principle. In the traditional method, the detection on small cracks in a plate is difficult to satisfy people, and therefore, the accuracy and the sensitivity of the traditional method are lowered. The method comprises the steps of: 1, transmitting transducer pumping signals: arranging a defined quantity of transducer arrays on a plate to be measured, and generating two pulse signals by a random waveform signal generator to be used as pumping signals; 2, selection of time reversal window signals: receiving transmission signals of the step 1 in a medium by a receiving transducer, carrying out nonlinear spectrum analysis on the received signals, and carrying out time reversal on the selected time window signals with nonlinear characteristic parameters; 3, obtained focus signals: loading the signals subjected to the time reversal in the step 2 to the transmitting transducer arrays again, and receiving the focus signals at the receiving part; and 4, defect or damage identification evaluation: analyzing the focus signals in the step 3, and finding out the relation between the defect or damage and the nonlinear characteristic parameters. The invention is applied to detection and identification of a plate structural member.

The invention discloses a material non-destructive inspection method and a material non-destructive inspection device based on nonlinear acoustics. The material non-destructive inspection method comprises the following steps that a Gaussian envelope is used for carrying out windowing on base frequency signals to form emitting signals; all subharmonic components in receiving signals are respectively subjected to filtering by a corresponding band-pass filter at the receiving end for realizing the separation of components at different frequencies; and in addition, all separated subharmonic components are subjected to corresponding matched filtering treatment for realizing the optimal detection of all harmonic components. The nonlinear acoustic detection method provided by the invention has the advantages that the frequency domain aliasing among all subharmonic components in signals is small, the nonlinear detection capability is high, and meanwhile, higher axial resolution capability is realized.

A nonlinear ultrasonic detection method for evaluating the thermo-oxidative ageing of an organic material comprises the following steps: building an organic material thermo-oxidative ageing damage nonlinear ultrasonic detection system based on a nonlinear acoustic detection system; respectively setting corresponding parameters of an excitation signal and a reception signal, and finely adjusting the corresponding parameters of the excitation signal and the reception signal by a time domain waveform signal observed and received by an oscilloscope; selecting the optimum work frequency range of a probe according to the frequency characteristic of the ultrasonic probe, and determining the initial frequency and the ending frequency of the swept frequency range; adjusting integrator gate parameters, carrying out frequency sweeping to obtain the change rule of an supersonic wave fundamental wave amplitude and a secondary harmonic amplitude with the frequency, and storing the change rule in a computer; calculating corresponding nonlinear coefficients of all frequency points in the swept frequency range, and calculating the accumulated nonlinear effect in the swept frequency range; and determining a corresponding relationship between the accumulated nonlinear effect and the thermo-oxidative ageing time of the organic material, and assessing the existence or not and the degree of the thermo-oxidative ageing damage of the organic material.

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 invention discloses an echo suppression method and device. The echo suppression method comprises the steps of suppressing linear echo component in a first audio signal to obtain a first echo suppression signal; suppressing nonlinear echo component in a second audio signal based on the first echo suppression signal to obtain a second echo suppression signal, wherein the first audio signal and the second audio signal are collected by audio receivers in an audio receiver array; and suppressing the linear echo component and the residual nonlinear echo component in the second echo suppression signal, respectively. The echo suppression method and device can efficiently suppress the linear and nonlinear acoustic echoes.

A method for determining incipient mechanical failure of an object includes insonifying the object with ultrasonic energy at a selected fundamental frequency. Amplitude data is acquired from the insonified object at the fundamental frequency and at a second harmonic of the fundamental frequency, and a non-linear acoustic image is generated from the amplitude data at the fundamental frequency and the second harmonic frequency.

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.

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.

The invention discloses a nonlinear ultrasonic heat treatment process evaluation and optimization method and device. The method comprises the following steps: acquiring an ultrasonic baseband signal A1 propagated in a test piece and amplitude A2 of second harmonics, and calculating a nonlinear acoustic parameter beta' of the test piece, wherein the expression is as shown in the specification; and comparing the difference between nonlinear acoustic parameters of an untreated material and a material subjected to different heat treatment processes based on the obtained relative nonlinear acoustic parameter beta'. The better the heat treatment process is, the more uniform the interior structure of the material subjected to heat treatment is, the performance is greatly improved, and the acoustic nonlinear response of ultrasonic propagation is low. The microstructure of the material can be changed based on heat treatment, a direct correlation exists between the nonlinear response of ultrasonic propagation and the microstructure of the material. According to the method, the heat treatment process effects can be nondestructively, rapidly and effectively evaluated, and the related parameters of heat treatment process are optimized and perfected.

The invention discloses a defect detecting method for a junction surface of metal alloy. The defect detecting method for the junction surface of the metal alloy includes the steps that a frequency mixing signal is adopted to receive and detect defect dual channel incentive-single channel at the junction surface of the metal alloy; a low-frequency component in the frequency mixing signal is eliminated through a high-pass filter, and a high-frequency component in the frequency mixing signal is eliminated through a band-pass filter, and a nonlinear sidelobe component is obtained through the low-frequency component and the high-frequency component; synchronous demodulation of the nonlinear sidelobe component is achieved through the high-frequency component, the high-frequency part is filtered, and the nonlinear base band component generated in the defect at the junction surface is retained; wavelet analysis is performed on the nonlinear base band component to obtain a wavelet energy value of the nonlinear base band component, and whether the junction surface of the metal alloy exists defects or not is judged according to the wavelet energy value; the positioning of a defect position is achieved through nonlinear acoustic same-side excitation frequency mixing positioning method according to nonlinear sidelobe component wavelet energy values of different delayed moments.

The invention provides a nonlinear circumferential ultrasonic wave guiding method for damage evaluation of a metal round tube. The nonlinear circumferential ultrasonic wave guiding method comprises the following steps of calculating a phase velocity dispersion curve according to physical parameters and geometric parameters of a metal round tube specimen to be measured; fatigue loading: loading to a scheduled cycle according to a scheduled plan to obtain a normalization value beta; repeatedly loading until fatigue loading is performed on a final scheduled cycle, and measuring a relation curve that a nonlinear acoustic parameter beta of circumferential ultrasonic wave guiding changes along with a load cycle index M; obtaining a damage degree under given loading conditions according to the beta-M relation curve. The nonlinear circumferential ultrasonic wave guiding method provided by the invention has the beneficial effects that a whole round tube member is covered by adopting nonlinear circumferential ultrasonic wave guiding detection, so that a damage state of round tube members / materials is effectively detected and evaluated, and a reliable reference is provided for safe use of the round tube members / materials; the nonlinear circumferential ultrasonic wave guiding method has the advantages of high detection speed, low detection cost and high detection accuracy.

Apparatus (10) and methods for combining time reversal and elastic nonlinearity of formation materials for qualtitatively probing for over-pressured regions down hole in advance of a well drilling bit, to determine the distance to the over-pressured region, and for accurately measuring pore pressure downhole in a formation, are described. Classical and reciprocal time reversal methods may be utilized to achieve these measurements.

An apparatus for imaging an earth formation, the apparatus including: a logging instrument configured to be conveyed through a borehole penetrating the earth formation; a source of acoustic waves disposed at the logging instrument, wherein the source is configured to emit first acoustic waves having at least a first frequency and to enable intermodulation of the first acoustic waves in a medium having a nonlinear acoustic property resulting in generating new acoustic waves that are transmitted to the earth formation, the new acoustic waves having a new frequency different from the at least first frequency; and a receiver of acoustic waves configured to receive the new acoustic waves reflected from the earth formation, wherein the received new acoustic waves provide an image of the earth formation.

The invention relates to a micro-crack identification and positioning system for a thin metal plate and a detection method based on the system, relating to the field of non-destructive testing of a thin metal plate. It solves the problem of low accuracy of the existing ultrasonic identification of micro-cracks and the difficulty in extracting subsequent feature signals, and simplifies the extraction method of nonlinear acoustic feature parameters. The hardware system includes keyboard, mouse, printer, industrial computer, expansion station, position sensor probe, sound wave receiving / transmitting hardware module, piezoelectric transducer array, metal sheet to be tested, five data transmission lines, and two sets of PCI peripheral components Internet mark. The software system includes a system management module, an acoustic wave signal processing module, a position information processing module, a display output software module and a post-processing module. The software system is a set of real-time detection and control programs, which use data visualization technology to intuitively display and output the ultrasonic signal data during the test process and the analysis data of the micro-cracks of the metal plate. The invention is suitable for detecting micro-cracks in thin metal plates.

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.

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,

The invention relates to a vibrator unit and a nonlinear acoustic metamaterial cellular structure based on the oscillator unit, and belongs to the field of mechanical engineering, mechanics and meta-materials. The vibrator unit and the nonlinear acoustic metamaterial cellular structure based on the oscillator unit aim to realize ultra-low-frequency ultra-wideband vibration reduction of the strongnonlinear acoustic metamaterial design and structure. The multi-vibrator physical coupling is applied to generate a strong nonlinear effect, so that a vibrator unit is formed, and a metamaterial cellis designed on the basis of the vibrator unit. The metamaterial cell can generate a low-frequency nonlinear locally resonant band gap and a broadband chaotic band, and the chaotic band width is controlled by a bridge connection coupling with different resonance. The strong nonlinear acoustic metamaterial structure with cellular design can be applied to generate super-low-frequency ultra-wideband vibration suppression effect.

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 discloses an active single-direction acoustic propagation device and a method for realizing single-direction acoustic propagation, wherein the propagation device is composed of two loudspeakers and two microphones; the two loudspeakers are combined to form a controlled acoustic source; a reference boundary is formed at one side of the controlled acoustic source; the two microphones are located at the two sides of the reference boundary and the space between the two microphones is smaller than the wavelength of the acoustic waves; the two microphones are used for measuring a sound pressure signal of backward sound pressure generated by an external acoustic source; the controlled acoustic source is used for emitting acoustic waves for counteracting the backward sound pressure generated by the external acoustic source. Compared with a single-direction acoustic propagation device structured with a strongly nonlinear acoustic medium, the active single-direction acoustic propagation device is composed of the conventional loudspeakers and microphones, and thus is simple in structure and easier to implement.

The invention discloses an ultrasonic nonlinear imaging system. The ultrasonic nonlinear imaging system comprises a pulse generator and a drive pulse voltage amplifier circuit. By means of quick change of excitation voltage and receiving of echo signals corresponding to drive pulses with quickly changed transmitting voltages, analog-digital conversion is carried out after corresponding gain amplification is completed; the transmitting voltages of the drive pulses and amplifier gains of the corresponding echo signals are proportioned, and echo envelope signals with different excitation voltage gain ratios are firstly subjected to nonlinear preprocessing including depth (time) compensation and the like aiming at nonlinear effect; a nonlinear processing unit obtains the envelope signals after nonlinear preprocessing to generate nonlinear images related to nonlinear acoustic parameter distribution in a tested object by means of operations including logarithm transformation, subtraction and the like. By the ultrasonic nonlinear imaging system, high efficiency in acquisition of nonlinear ultrasonic images higher in image quality can be obtained.

The invention discloses a non-classical nonlinear detection method aiming at micro crack in non-uniform members. The method is as below: an energy-gathered energy transducer is coupled in one end of a non-uniform member, so that the other end of the non-uniform member is in a free state; the energy-gathered energy transducer applies forced periodic vibration force on one end of the non-uniform member to stimulate large strain wave, and the large strain wave stimulates non-classical nonlinear acoustic wave propagation at the microcrack in the non-uniform member, so as to obtain in higher order odd harmonics; and four laser displacement sensors fixed in the length direction of the non-uniform member perform non-contact measurement, and location and width of the micro crack are acquired through computer processing. The method of the invention can effectively identify and locate the micro crack in the non-uniform member, and is high in accuracy and not affected by transmission loss. The invention provides an effective way for early detection and localization of micro cracks in non-uniform member for the engineering field, and has significant practical value.

An intraocular pressure measurement arrangement is disclosed for measuring pressure of an eye of a patient. The arrangement can detect at least one of acoustic reflectivity, optical reflectivity, optical path difference, positioning of intraocular pressure measurement arrangement with respect to the eye, orientation of intraocular pressure measurement arrangement with respect to the eye, shape of cornea and corneal thickness. At least one source can produce acoustic, nonlinear acoustic, mechanical or a nonlinear mechanical wave from a distance, coupling to the eye to generate at least one surface wave. Upon triggering data acquisition, at least one surface wave from a distance from the eye can be detected to extract surface wave information with pressure information of the eye being based on the surface wave information.

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.

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.

The invention provides a method of designing a high-power energy-gathered reflex housing. The method includes the steps of designing an appearance structure of the energy-gathered reflex housing according to principle of the optimum cost-benefit ratio, generating an ideal curved surface type value table; conducting dynamics and nonlinear acoustics analysis on the energy-gathered reflex housing, optimizing the reflex housing structure, obtaining a revised curved surface type value table and generating curved surface machining data. Due to the fact that dynamics analysis and nonlinearity factors are overall considered, the molded surface of the energy-gathered reflex housing is optimally designed in a system integrated mode, design efficiency of the energy-gathered reflex housing is greatly improved, optimum energy-gathered directed radiation performance is obtained. Due to the fact that the energy-gathered reflex housing is designed according to the principle of the optimum cost-benefit ratio, the volume, the weight and manufacturing cost of the energy-gathered reflex housing are reduced, installation and arraying of a carrying platform are convenient, and energy-gathered comprehensive effect of the energy-gathered reflex housing reaches the optimum reflex effect of the ideal molded surface under the condition of rated load due to the fact that nonlinear effect is considered and the molded surface of the energy-gathered reflex housing is revised.

Apparatus and methods for measurement of pore pressure in rock formations through an open, or cemented and / or cased, borehole are described. Such measurements are achieved using the Dynamic Acoustic Elasticity (DAE) method for characterizing nonlinear parameters by perturbing a selected rock formation volume with a High Amplitude, Low Frequency (HALF) acoustic strain wave, and probing this volume using a Low Amplitude, High Frequency (LAHF) acoustic wave. Time reversal techniques may be employed for focusing acoustic energy Into the formation in the vicinity of the pipe or open hole.

The invention discloses a wind speed measurement method based on a parametric array, belonging to the field of employing sound waves to measure wind speeds. The parametric array can generate a high directivity audible acoustic beam, thereby overcoming the advantage that wind speed measurement is susceptible to multi-path interfere; meanwhile, the invention utilizes the nonlinear acoustic parameter--sound pressure level in an parametric array to measure wind speed change, and overcomes the disadvantages of single measurement of a traditional sound wave wind speed measurement method which only utilizes the linear rule of sound wave propagation speeds with the change of wind speeds to obtain wind speed values. The invention not only possesses the advantages of a traditional sound wave wind speed measurement method, and meanwhile has specific advantages in the fields of large range space wind speed measurement and wind speed measurement of higher accuracy.

The invention discloses a cluster acoustic wave precipitation enhancement device, comprising an acoustic wave sound generator (5), an acoustic wave transducer (4), a cylindrical box cover (2), a matrix type energy-gathering trumpet (3), and an energy-gathering cylindrical acoustic wave cover (1), wherein the acoustic wave sound generator (5) generates certain high-frequency electric energy supplied to the acoustic wave transducer (4), then the electric energy is transmitted to the energy-gathering cylindrical acoustic wave cover (1) by using the directional matrix type energy-gathering trumpet (3), and a nonlinear acoustic effect of air is generated in the energy-gathering cylindrical acoustic wave cover (1), so that controllable artificial precipitation is achieved. The cluster acoustic wave precipitation enhancement device disclosed by the invention is environmentally friendly and free from pollution free, strong in directivity, small in airspace restriction, and high in preparatory work and operation efficiencies.