8 results about "Small amplitude" patented technology

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 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.

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.

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.