16 results about "Particle velocity" patented technology

The invention discloses a plateau frozen soil thickness detecting and monitoring method and system based on distributed optical fiber acoustic sensing. The method comprises the steps that a spiral optical fiber and a linear optical fiber are arranged in frozen soil according to a preset observation position, and vibration signals are collected through the spiral optical fiber and the linear optical fiber respectively; the collected vibration signals are preprocessed, and the vibration signals are converted into particle velocity signals; vector decomposition is carried out on two mass point velocity signals obtained by the spiral optical fiber and the linear optical fiber, and a surface wave component is inhibited to enhance a mass wave component; carrying out self-excitation and self-receiving recording on the measuring point position according to the data after vector decomposition; recording data and picking up frozen soil upper and lower limit travel time; according to the frozen soil upper and lower limit travel time, the overlying stratum speed and the frozen soil layer speed, obtaining the frozen soil upper limit burial depth and the frozen soil thickness. The device can output the spatial distribution condition of the frozen soil in real time, monitors the buried depth, thickness and upper and lower limit positions of the frozen soil in real time, improves the geological interpretation effect for railway investigation and design, and provides a scientific basis for safe operation of the railway.

The present invention discloses a method for measuring the shear wave velocity of the shallow seafloor sediment layer based on a single vector hydrophone. The measurement method includes: collecting underwater acoustic signals and seafloor interface wave signals excited by a very low frequency sound source near the seafloor using a single vector hydrophone; obtaining the horizontal component of the particle velocity by rotating the quasi-source direction using the horizontal transverse component and the horizontal longitudinal component of the particle velocity; calculating the amplitude ratios between the sound pressure, the vertical component of the particle velocity, and the horizontal component of the particle velocity pairwise, and calculating the interface wave velocity using any one of the amplitude ratios; and finally calculating the shear wave velocity according to the linear relationship between the interface wave and the shear wave. The method of the present invention can accurately estimate the shear wave velocity of the shallow seafloor sediment layer, and the detection device only requires a single vector hydrophone, providing a feasible technical approach for solving long-term problems such as difficult seafloor shear wave measurement, high cost, and low efficiency.

The present application belongs to the field of sound field reconstruction and sound source identification technology, and discloses an equivalent source sound field positioning method and system based on sparse sound intensity measurement, which acquires the complex sound pressure and complex particle velocity at the measurement point on the holographic surface through a vector sensor array, and calculates the measured sound intensity vector; constructs a sound intensity transfer matrix based on the equivalent source method, establishes a linear measurement equation between the measured sound intensity vector and the equivalent source intensity vector; by using the spatial sparsity of the equivalent source intensity, the solving of the equivalent source intensity vector is converted into an L1 norm sparse optimization problem, and a convex optimization algorithm is used to solve it to obtain the optimal equivalent source intensity vector; based on the optimal equivalent source intensity vector, the acoustic quantity at any point in the target sound field is reconstructed by combining the free field Green function. The present application uses the active component of the sound intensity vector to suppress non-related noise, improves the ill-conditioned inversion by combining the compressive sensing theory, and can realize high robustness and high precision sound source positioning and sound field reconstruction without reference microphones.

The present invention provides a method for estimating the depth of a moving target based on a single vector hydrophone, which uses the vector hydrophone to receive sound pressure and particle velocity signals; constructs a sound pressure-particle velocity cross-spectrum; performs time-domain equally-spaced discretization processing on the received sound pressure and particle velocity signals to construct a discrete signal matrix; obtains the preliminary noise-reduced sound pressure and particle velocity signals; decomposes the signals through EWT, estimates the signal frequency according to the LOFAR spectrum analysis, determines the mode function component containing the frequency, and reconstructs the signals; constructs a sound pressure-particle velocity sound field spatial interference spectrum; calculates the horizontal complex sound intensity and the vertical complex sound intensity to estimate the vertical arrival angle of the target direct wave; performs a discrete Fourier transform on the sound pressure-particle velocity sound field spatial interference spectrum along the curve of the vertical arrival angle of the target direct wave, and the sub-maximum value after removing the maximum value at the vertical symmetry axis corresponds to the target depth estimation value. The present invention realizes the estimation of the depth of a moving target by using the received signals under the influence of noise, and has good practical engineering application capabilities.

The invention relates to a method for calculating porous medium two-phase flow energy dissipation based on a particle velocity measurement method, and belongs to the technical field of porous medium seepage mechanics experiments. The invention discloses a method for calculating porous medium two-phase flow energy dissipation based on a particle velocity measurement method. The method comprises the following steps: preparing a transparent pore medium microscopic model with a specific microscopic pore structure; carrying out a visual multiphase flow experiment on the pore medium microscopic model; determining external input work based on the inlet and outlet pressure data; accurate calibration of space and phase state is carried out on the original image, and interface energy is obtained through calculation; determining a velocity vector of a non-wetting phase in an experiment based on a particle velocity measurement method, and calculating to obtain kinetic energy; and determining the ratio of energy dissipation to total energy in the multiphase flow system based on external input work, interface energy and kinetic energy. According to the method, the conversion from a visual flow image to a quantitative energy component can be realized, and the viscous dissipation and the interface energy in the displacement process are accurately calculated, so that an energy dissipation mechanism is disclosed, and a key data support is provided for engineering optimization and numerical simulation.

The present invention discloses a method and system for detecting and monitoring the thickness of permafrost on the plateau based on distributed fiber optic acoustic sensing. The method includes deploying spiral and linear optical fibers in the permafrost according to predetermined observation locations, collecting vibration signals using the spiral and linear fibers, respectively; preprocessing the collected vibration signals to convert them into particle velocity signals; vector decomposing the two particle velocity signals obtained from the spiral and linear fibers to suppress the surface wave component and enhance the body wave component; self-excited and self-received recording of the measurement point locations based on the vector decomposition data; extracting the upper and lower limit travel times of the permafrost from the recorded data; and obtaining the upper and lower limit burial depth and thickness of the permafrost based on the upper and lower limit travel times of the permafrost and the velocity of the overlying strata and the permafrost layer. The present application can output the spatial distribution of permafrost in real time, monitor the buried depth, thickness, and upper and lower limit positions of the permafrost in real time, and provide a scientific basis for improving geological interpretation for railway survey and design and ensuring safe railway operation.

Apparatus is provided for assessing a characteristic of a first acoustic field (22) at a first frequency in a region (24) of a medium (26), the first acoustic field generating oscillatory motion of scatterers (28) disposed within the medium, at the first frequency. An acoustic transducer (30) (a) generates a second acoustic field (32) at a second frequency in the region, the second frequency being higher than the first frequency, and (b) receives echo data of the second acoustic field scattering off the oscillating scatterers in the medium, the echo data containing Doppler-shifted frequencies related to the oscillations of the scatterers, resulting in a time-dependent Doppler shift that oscillates at a frequency that is related to the first frequency. Control circuitry (36) (a) extracts the oscillating time-dependent Doppler shift from the received echo data, and (b) converts the extracted Doppler shift into particle-velocity of the first acoustic field.

To provide full automation of high-resolution interval velocity estimation for check-shot and other vertical seismic profile-type datasets.SOLUTION: A method includes the steps of: disposing sensors within a borehole; disposing seismic sources on a surface away from a wellhead of the borehole at a field location; propagating seismic waves using the seismic sources; obtaining particle velocity data from geological stratum in the field location; obtaining strain data from the geological stratum in the field location; performing a peak-to-peak amplitude analysis for the particle velocity data for a target phase; performing a peak-to-peak amplitude analysis for the strain data for the target phase; and estimating a velocity of waves in the geological stratum based upon the peak-to-peak amplitude analysis for the particle velocity data for the target phase and the peak-to-peak amplitude analysis for the strain data for the target phase.SELECTED DRAWING: None

The present invention discloses a low-frequency acoustic tube measurement method for the vibration velocity transfer coefficient of underwater acoustic materials, which includes the following steps. Step 1: The low-frequency acoustic tube is placed vertically, and a transmitting transducer is installed at its bottom. Two hydrophones are embedded in the low-frequency acoustic tube wall at intervals, and the low-frequency acoustic tube is filled with degassed water medium. Step 2: The underwater acoustic material to be measured is placed in the low-frequency acoustic tube and located on the water surface. The gap between the underwater acoustic material to be measured and the low-frequency acoustic tube wall is filled with water medium, and the upper surface of the underwater acoustic material to be measured is a rigid backing. An accelerometer is installed on the rigid backing, and a cavity is provided between the rigid backing and the upper cover of the low-frequency acoustic tube. The present invention realizes the measurement of the vibration characteristic parameters of the underwater acoustic material sample in the low-frequency acoustic tube, can fully simulate the working conditions of the sample in actual work and the structure of the submarine acoustic covering layer, and the measurement frequency band is concentrated in the range of 100 Hz to 1 kHz where it is difficult to reduce vibration and noise in submarine shock absorption technology.

Systems and methods may be used to reconstruct particle velocity wavefields from coupling-calibrated fiber-optic data that subsequently enables physically valid construction of the particle velocity wavefields for a hybrid sensor array including both fiber-optic and particle motion sensors. These systems and methods may be used in a variety of borehole geophysical applications, such as structure and reservoir imaging, impedance inversion, attenuation tomography, micro-seismic fracture imaging, focal mechanism analysis, and so on. The systems and methods may also be used in other applications such as geothermal and CO2 storage monitoring.

The application relates to a vector sound field fast prediction method and device based on ray theory and relates to the technical field of underwater acoustics. In order to solve the problems that the differential method prediction causes the increase of calculation amount, the reduction of calculation efficiency and the superposition method causes the reduction of the precision of particle velocity prediction in the prior art, the technical scheme is as follows: the vector sound field fast prediction method based on ray theory comprises the following steps: collecting preset marine parameters, sound source parameters and receiver parameters, obtaining the sound ray track from the sound source to the receiver and the time delay parameters corresponding to the track points on the track according to the parameters; obtaining the sound beam equation of the sound ray emitted at a preset grazing angle from a to-be-simulated point according to the sound ray track and the time delay parameters; obtaining the particle velocity of the to-be-simulated point in the tangent direction of the sound ray track according to the sound beam equation; and obtaining the sound pressure, the particle velocity in the horizontal direction and the particle velocity in the vertical direction of the to-be-simulated point according to the sound beam equation, the particle velocity and the sound ray track. The application is suitable for the work of the vector sound field fast prediction.

The present application relates to a method for designing a long-beam acoustic focusing lens, comprising the following steps: designing a two-dimensional lattice array, wherein the two-dimensional lattice array is composed of rigid star-shaped columns in the air. According to the two-dimensional lattice array, the sound pressure equation of the incident wave and the sound pressure equation of the first scattering of different star-shaped columns are constructed. According to the visco-thermal effect of the solid wall interface, the boundary conditions of the radial particle velocity on the surface of the star-shaped column are constructed. The sound pressure equation at any point on the plane is constructed. The method constructs the sound pressure equation of the incident wave and the sound pressure equation of the first scattering of different star-shaped columns by designing a two-dimensional lattice array, and constructs the boundary conditions of the radial particle velocity on the surface of the star-shaped column and the sound pressure equation at any point on the two-dimensional plane according to the visco-thermal effect of the solid wall interface. The two-dimensional lattice array composed of rigid star-shaped columns forms a topological structure. The characteristics of the topological structure enable the method to achieve more efficient long-beam projection for low-frequency broadband.

This invention belongs to the field of sound field reconstruction and sound source identification technology. It discloses an equivalent source sound field localization method and system based on sparse sound intensity measurement. The method involves acquiring complex sound pressure and complex particle velocity at measurement points on a holographic surface using a vector sensor array, and calculating the measured sound intensity vector. A sound intensity transfer matrix is ​​constructed based on the equivalent source method, establishing a linear measurement equation between the measured sound intensity vector and the equivalent source intensity vector. Utilizing the spatial sparsity of the equivalent source intensity, the solution for the equivalent source intensity vector is transformed into an L1 norm sparse optimization problem, solved using a convex optimization algorithm to obtain the optimal equivalent source intensity vector. Based on the optimal equivalent source intensity vector, the acoustic quantities at any point in the target sound field are reconstructed using a free-field Green's function. This invention utilizes the active component of the sound intensity vector to suppress uncorrelated noise and combines compressed sensing theory to improve the ill-conditioned nature of the inversion, achieving highly robust and accurate sound source localization and sound field reconstruction without the need for a reference microphone.

In example implementations described herein, there are systems and methods for performing predictive maintenance which can include collecting vibration data related to an operation of a first machine during a first time period, computing sound data related to the operation of the first machine during the first time period based on the collected vibration data, and predicting, based on the computed sound data, at least one value associated with a maintenance of the first machine. In some aspects, the systems and methods may further include measuring an acoustic transfer function relating the vibration data related to the operation of the first machine to one or more of the sound pressure data or the particle velocity data.

The present invention discloses a method for merging vector hydrophone sound pressure and velocity signals under correlated noise. Step 1: intercept the noise part of the sound pressure and velocity channel signal of the orthogonal multi-carrier bandpass continuous signal received by the vector hydrophone, and estimate the noise correlation coefficient ρ between the three channels. <subgt;ij< / subgt;,i.j∈[1,2,3];步骤2、假设多普勒因子已经被估计和补偿,多普勒扩展因子α=0,根据信道时域响应模型得到信道频域响应模型,假设各子载波的能量相等,得到声压P,振速Vx,振速Vy接收第k个子载波的信道频域响应模型;步骤3、利用声压振速互谱法得到信号源的估计方位角;步骤4、根据估计方位角和各通道噪声相关系数,计算得到声压振速通道最优加权值,合并成单通道信号。本发明在不增加复杂度的情况下,使得矢量水听器作为水下通信接收端获得更大的信噪比和更好处理增益。

Apparatus is provided for assessing a characteristic of a first acoustic field (22) at a first frequency in a region (24) of a medium (26), the first acoustic field generating oscillatory motion of scatterers (28) disposed within the medium, at the first frequency. An acoustic transducer (30) (a) generates a second acoustic field (32) at a second frequency in the region, the second frequency being higher than the first frequency, and (b) receives echo data of the second acoustic field scattering off the oscillating scatterers in the medium, the echo data containing Doppler-shifted frequencies related to the oscillations of the scatterers, resulting in a time-dependent Doppler shift that oscillates at a frequency that is related to the first frequency. Control circuitry (36) (a) extracts the oscillating time-dependent Doppler shift from the received echo data, and (b) converts the extracted Doppler shift into particle-velocity of the first acoustic field.