13 results about "Small amplitude" patented technology

The invention relates to a bridge structure modal parameter identification method, which is based on a bridge structure tiny vibration video acquired by a camera. VMD (variational mode decomposition), PBVM (phase-based video motion amplification), Gabor filtering-based phase extraction method GBP (Gabor filtering), an improved clustering algorithm ICA (independent clustering algorithm) and an integrated covariance-driven random subspace recognition (SSI-Cov) and FDD (frequency domain decomposition) algorithm are fused to construct a set of complete non-contact structural modal parameter recognition system. According to the method, effective decoupling of multiple vibration modes of a bridge structure, frequency domain feature extraction of small-amplitude vibration and intelligent and automatic modal parameter extraction are achieved under the conditions that the target frequency bandwidth does not need to be known in advance, environmental noise interference exists and no obvious feature target exists, and the method belongs to the technical field of bridge structure health monitoring.

The invention discloses a non-linear aerodynamic damping identification method and system for self-excitation hysteresis vibration and a storage medium. The method comprises the steps that structure wind-induced vibration response data is acquired; aerodynamic damping is modeled as a non-monotonic high-order function about the amplitude, and an expansion state vector and state space model containing damping parameters and load items is constructed; performing recursive estimation on the state vector by using a filtering algorithm, and synchronously identifying a damping parameter; calculating a damping-amplitude curve according to the parameters; a full-amplitude domain splicing strategy is adopted, a small-amplitude interval high-precision recognition result is fused to correct the large-amplitude interval recognition curve, and a high-precision target damping curve is obtained; by analyzing the intersection point and slope of the curve and the structural damping line, stable and unstable balance points are identified. The method solves the problems that a traditional method cannot accurately describe the multistable hysteretic phenomenon and the recognition precision of a small amplitude interval is insufficient, and high-precision recognition of nonlinear aerodynamic damping and quantitative analysis of a hysteretic mechanism are achieved.

The present invention discloses a high-frequency, small-amplitude vibration-assisted laser cladding apparatus and method for large workpieces. In the apparatus, parallel wavy cams are installed coaxially and with equal phase difference and mounted on the main shaft of an upper stationary box. The wavy cams are short-amplitude outer linear cams. The parallel wavy cams and corresponding cantilever beams form a vibration source. The corresponding cantilever beam assemblies are mounted inside a lower movable box. The upper stationary box assembly and the lower movable box assembly form a closely spaced movable pair. The lower movable box is mounted on a vibration receiving plate. The right end of the high-natural frequency spring is fixedly supported by a pair of high-natural frequency springs, the lower end of which is fixedly supported by a frame. The wavy cams are driven by a motor via a pulley. The amplitude of the processed workpiece can be adjusted according to needs, and the vibration frequency of the processed workpiece can be changed by changing the number of wavy cams and the corresponding cantilever beams. This method is particularly applicable to grain refinement, stress relief, homogeneous phases, and forged structure formation through vibration-assisted laser cladding.

The invention discloses a high-response acoustic emission sensor based on an acoustic structure, and belongs to the technical field of acoustic emission sensors. The invention solves the problems of weak response to an acoustic emission source, small amplitude of received signals and low signal-to-noise ratio of acoustic emission signals generated by early wear, fatigue cracks and other defects and received by the traditional acoustic emission sensor when the environmental noise is relatively large in the existing acoustic emission sensor. Comprising a shell, an acoustic structure cavity, a Fresnel lens, a circular-truncated-cone-shaped piezoelectric element, a connector and a distance adjusting bolt, the shell is fixedly buckled on the Fresnel lens, the acoustic structure cavity comprises an installation plate and at least one first circular ring fixedly installed on the lower end face of the installation plate, and when the number of the first circular rings is multiple, the first circular ring is connected with the connector. The diameters of the first circular rings are different, and the first circular rings are sequentially and coaxially arranged from inside to outside. According to the invention, the response capability of the sensor to an acoustic emission source, the amplitude of a received signal and the signal-to-noise ratio are obviously improved.

The invention belongs to the technical field of typical weak signal detection, and particularly relates to a direct-current weak voltage signal acquisition system and method based on an FPGA, and the system comprises a pre-amplification module, a chopper module, a differential amplification module, the FPGA, a band-pass filtering module, and an ADC module. A multi-stage signal conditioning framework is adopted, and the problems that a direct-current weak signal is prone to noise interference, the dynamic range is limited, the system response speed is low, and the direct-current signal monitoring adaptability is poor are effectively solved. The system introduces an ultra-low noise precision operational amplifier to pre-amplify an input signal of the sensor, so that the problem of signal processing caused by too small amplitude in a signal monitoring process is avoided. In order to eliminate common-mode interference and low-frequency noise, a chopping modulation circuit is innovatively introduced. Aiming at the difference of output amplitudes of different sensors, the system is integrated with a gain attenuation module.

The invention relates to the technical field of gas pressure monitoring, and discloses a gas state sudden change intelligent decision-making method based on real-time pressure monitoring, which comprises the following steps: step 1, multi-modal data acquisition: focusing on resident scene perception requirements: a core monitoring target of a resident gas system is home-entry pipeline pressure, and pertinently configuring perception equipment; step 2, multi-dimensional data preprocessing: intensified pressure threshold interval signal reservation: the pressure fluctuation of a resident scene is mostly small and high in frequency, and the preprocessing needs to avoid loss of threshold boundary signals less than 0.1 kPa level while noise reduction is carried out; the gas state recognition precision and control flexibility are improved, the method is suitable for micro gas quantity detection, remote strategy synchronization and emergency behavior response in multiple scenes, the safety, intelligence and maintainability of equipment are enhanced, and the method is suitable for gas control in the fields of residential users, commercial kitchens and industries.

The application relates to a bridge structure modal parameter identification method, which is based on a bridge structure micro-vibration video collected by a camera, fuses a variational mode decomposition (VMD), a phase-based video motion magnification (PBVM), a Gabor filter-based phase extraction method (GBP), an improved clustering algorithm (ICA) and an integrated covariance-driven stochastic subspace identification (SSI-Cov) and frequency domain decomposition (FDD) algorithm, and constructs a complete non-contact structure modal parameter identification system. In the absence of prior knowledge of the target frequency bandwidth, environmental noise interference and without obvious characteristic targets, the effective decoupling of multiple vibration modes of the bridge structure, the frequency domain feature extraction of small-amplitude vibration and the intelligent and automatic modal parameter extraction are realized, and the application belongs to the technical field of bridge structure health monitoring.

A vibration device (1) is provided with: an internal vibration body (7) for increasing the amplitude of vibration; a piezoelectric element (9) that is connected to one end of the internal vibrating body in the first direction and that generates vibration; a translucent body (5) connected to the other end of the internal vibrating body in the first direction, the translucent body (5) having an optical axis extending in the first direction; and an external vibrating body (3) including a damping part (33) extending from the first connecting part to the outside of the light-transmitting body in the second direction and damping vibration, and a first connecting part (31) connected to the light-transmitting body. The damping section (33) has non-axisymmetric properties with respect to the optical axis, has a minimum value of impedance (= resonance resistance value), has a small loss due to resistance, and can form a region that vibrates at a large amplitude and a region that vibrates at a small amplitude on the surface of the translucent body (5) during vibration without increasing the resonance resistance value of the internal vibrating body (7). Foreign matter adhering to the light-transmitting body (5) is removed.

The application discloses a hole shaft interference fit deformation detection method and device based on small hole diffraction, and relates to the technical field of hole shaft interference fit deformation detection. The method comprises the following steps: installing a laser at the edge of a measured fitting hole; and using a laser point positioning assembly to detect the laser emission position before and after the interference fit of the measured fitting hole. According to the change of the light emission coordinates, the hole shaft interference fit deformation amount is judged. The laser is installed at the edge of the interference fit hole, and the positions of the laser before and after the interference fit are detected, so that the deformation amount caused by the interference fit is determined, and whether the deformation amount of the hole shaft interference fit exceeds the allowed range is detected quickly. The application utilizes the characteristics that small amplitude displacement can significantly affect the clarity and shape of the light ring between light and dark in the small hole diffraction image, and realizes accurate detection of the target position coordinates by using a camera and a laser, thereby improving the accuracy of the hole shaft interference fit deformation detection.

This invention relates to a method for extrapolating the extreme values ​​of time-domain wave loads based on truncated samples and a three-parameter distribution. The method comprises the following steps: extracting amplitude samples from the original time history; removing a predetermined number of smaller amplitude samples to obtain truncated samples (x1, x2, ... x...). m The cutoff sample (x1, x2, ... x) obtained by fitting the three-parameter generalized extreme value distribution G(x; σ, γ, μ) is selected. m The method involves estimating the scale parameter σ, shape parameter γ, and position parameter μ using the probability weighted moments method, and obtaining the corresponding extrapolated extreme values ​​X of the wave load. This invention provides an extrapolation method for wave load extreme values ​​that balances rationality, stability, and accuracy. Compared with existing technologies, the positive advancements of this invention are: it has the advantages of reasonable amplitude extraction, appropriate distribution function selection, and high extrapolation accuracy. While ensuring accurate and stable fitting of wave load samples, it can conveniently perform extreme value extrapolation.

The invention provides a signal noise reduction method and a gas concentration detection method based on an improved threshold function. The signal noise reduction method comprises the following steps: decomposing an original signal containing noise into a plurality of signal components; wavelet threshold noise reduction processing is carried out on at least part of the signal components, and wavelet coefficients are processed through an improved threshold function in the processing process; and performing signal reconstruction based on a wavelet threshold noise reduction processing result to obtain a de-noised signal. A threshold function containing an exponential attenuation item is introduced, the function is continuous and smooth at a threshold point, when the amplitude of a wavelet coefficient is just larger than a threshold, the function can provide smooth shrinkage similar to a soft threshold, and signal oscillation caused by a hard threshold function is effectively avoided; when the amplitude of the wavelet coefficient is far greater than a threshold value, the exponential attenuation item rapidly approaches zero, so that the processed coefficient infinitely approaches the original coefficient; noise with small amplitude can be filtered out, high-fidelity preservation can be carried out on a large-amplitude coefficient, and the signal noise reduction precision and the waveform fidelity are remarkably improved.

The application discloses a kind of slender shaft turning outer circle processing method based on main shaft speed periodic disturbance, the method will slender shaft turning part be divided into stable region, cantilever beam region and tool abnormal wear region, with the time of tool in axial direction processing as trigger signal in cantilever beam region and tool abnormal wear region, and with this factor as period, by small amplitude adjustment main shaft speed, and then the axial feed speed of blade and instantaneous acceleration also periodically change, the cutting force that part bears also periodically changes, destroys the condition that part and blade produce resonance, solve the problem such as existing slender shaft outer circle surface exists vibration tool mark, surface roughness is poor etc..

The application discloses a kind of self-adapting rotor position error compensation methods based on low-frequency sinusoidal signal injection, specifically: a small amplitude low-frequency sinusoidal signal is injected into rotor position signal;Based on the small amplitude low-frequency sinusoidal signal injection, the mathematical model of permanent magnet synchronous motor under γδ coordinate system is constructed;The component and of voltage on γ axis and δ axis are obtained;Two parameters consistent generalized integrator voltage signals are processed;The amplitude of two sets of orthogonal signals is calculated;And based on amplitude, construct objective function;Solve the screen objective function, obtain the rotor optimal position error compensation value.It has excellent robustness, without accurate modeling, the difference between estimated rotor position signal and actual rotor position signal can be extracted, and the estimated rotor position signal is compensated according to rotor position error.