14 results about "Frequency ratio" patented technology

The invention provides a bridge vortex-induced vibration and flutter control TMDI parameter optimization method, which comprises the following steps of: according to a selected inertia mass ratio, obtaining optimal values of parameters under a control target by adopting a GBO optimization algorithm, wherein the optimal values are a TMDI mass ratio, a frequency ratio and a damping ratio; according to the optimization algorithm, the target function Fs converges to the minimum individual, namely the minimum TMDI mass ratio, and the minimum TMDI mass ratio and the corresponding optimal parameter, namely the optimal combination parameter. The invention further provides equipment, a storage medium and a program product. Compared with the prior art, the method has the advantages that the most economical TMDI optimization parameters can be obtained while effectiveness and robustness are considered.

The invention belongs to the technical field of bridge vibration reduction, and discloses a TMD parameter design method for modal dense bridge multi-modal vortex vibration control. Modal analysis is carried out on the target bridge, and modal frequency, vibration mode and modal mass where vortex vibration possibly occurs are extracted; then based on a modal shape amplitude threshold, screening significant extreme points of each order of modal, calculating the number of the significant extreme points, and determining the priority of TMD design according to the number from small to large; for a mode with the number of extreme points being 1, the TMD is installed at the unique position; for a mode with the number of extreme points exceeding 1, the TMD mass is split and arranged at symmetrical positions meeting the mode decoupling condition, and therefore mode coupling caused by improper installation positions is avoided. And finally, determining the frequency ratio and the damping ratio of each TMD based on a Den Hartog empirical formula. The method does not need a complex optimization algorithm, is simple in design process, and is suitable for engineering practice; and modal coupling can be effectively inhibited, and the multi-modal vortex vibration control efficiency is improved.

The application provides an alarm method, comprising the following steps: a. filtering a vibration signal to obtain a first noise signal; b. judging whether the maximum amplitude of the first noise signal is greater than a preset amplitude threshold value, and if yes, recording the first noise signal and performing step c; c. obtaining the vibration signal before the first noise signal as a background noise signal, establishing an AR model of the background noise signal, and calculating the residual error of the first noise signal and the predicted signal of the AR model; d. calculating the sequential probability ratio test parameter of the residual error, and judging whether the sequential probability ratio is greater than a preset probability ratio threshold value for multiple times, and if yes, recording the time when the sequential probability ratio is greater than the probability ratio threshold value for the first time as a suspected time; e. calculating the amplitude probability density function of the residual error, and calculating the correlation coefficient of the amplitude probability density function of the residual error and the probability density function of a standard signal; and f. obtaining a frequency ratio according to the self-power density spectrum of the first noise signal at the suspected time.

The invention discloses a dangerous rock mass stability evaluation method and system based on an amplitude ratio and a frequency ratio, and relates to the technical field of geological disaster risk assessment, and the method comprises the steps: collecting dangerous rock three-way vibration data and bed rock three-way vibration data in the same time interval; the dangerous rock three-dimensional vibration data and the bedrock three-dimensional vibration data are synthesized into dangerous rock one-dimensional amplitude data and bedrock one-dimensional amplitude data respectively, and the ratio of the dangerous rock amplitude standard deviation to the bedrock amplitude standard deviation is calculated to obtain an amplitude ratio; calculating the ratio of the dangerous rock peak frequency to the bedrock peak frequency to obtain a frequency ratio; and inputting the amplitude ratio and the frequency ratio as inputs into a trained dangerous rock mass stability evaluation model, and identifying the stable state of the dangerous rock mass. According to the method, the problem that the accuracy of a stability evaluation result is insufficient due to excitation and equipment temperature drift in dangerous rock mass vibration monitoring in the prior art is solved.

The present invention discloses a method for identifying axial forces of rigid rods using a frequency ratio method. The steps are as follows: (1) Based on engineering data, determine whether the rigid rod is a compression rod or a tension rod, and obtain relevant parameters of the rigid rod: the rigid rod linear density m, the rigid rod length L, and the rigid rod bending stiffness EI; (2) Use a vibration sensor to collect the vibration signal of the rigid rod on-site and analyze the multi-order frequencies of the rigid rod; (3) Select a corresponding method to calculate the frequency ratio of the rigid rod based on whether the rigid rod is a compression rod or a tension rod and the boundary conditions, and calculate the axial force of the rigid rod using the frequency ratio method; (4) Verify the relative bending stiffness ξ of the rigid rod and evaluate the accuracy of the axial force identification of the rigid rod. The method of the present invention establishes a unified calculation method for identifying the axial forces of rigid tension rods and compression rods using the frequency ratio method. The method is easy to use and has good accuracy, providing a practical new method for identifying the axial forces of rigid rods.

This invention belongs to the field of charging management technology, specifically relating to an autonomous docking magnetic charging management system and method. First, real-time data from a magnetic field sensor and accelerometer are acquired to determine the current environmental interference intensity. Then, based on the interference intensity, the magnetic field direction of the magnetic attraction component is dynamically adjusted, and the corresponding magnetic torque compensation value is calculated to counteract external interference. Furthermore, this method monitors the real-time displacement and current changes at the docking interface to determine if a preset docking threshold has been reached. Based on the interference intensity and displacement change, a vibration frequency ratio is calculated to further optimize the magnetic torque compensation value. When the new compensation value causes the current change rate to be below the interference threshold for three consecutive cycles, the magnetic attraction component is locked, and docking is completed. This method significantly improves the docking success rate and charging stability in complex environments, and is particularly suitable for high-precision, low-tolerance docking interface designs.

This void ratio acquisition method includes: a measurement results acquisition step of acquiring measurement results by measuring, over a predetermined time period, the voltage in a gas-liquid two-phase flow by using a probe; a frequency distribution creation step of creating a frequency distribution indicating the frequency of voltage values; a phase discrimination step of determining, as a liquid phase level voltage, the value of the voltage of a first peak which is the most frequent; a noise acquisition step of acquiring, as noise, the frequency of the value of the voltage having a small absolute value with respect to the liquid phase level voltage; and a void ratio acquisition step of taking the difference of noise from the frequency of the value of a voltage having a large absolute value with respect to the liquid phase level voltage, acquiring a frequency, from which the noise was removed, as a frequency ratio of the gas phase in the gas-liquid two-phase flow, and acquiring a frequency ratio of the gas phase as a void ratio.

The present disclosure provides a system for automatic conversion of musical pieces to natural tuning based on contextual analysis, comprising a context input module configured to receive musical context information including note distribution, melodic motifs, harmonic content, temporal dependencies, metadata, and instrument data. The system includes a learning processor configured to process the musical context information using statistical and rule-based models to identify patterns linking musical context with natural tuning relationships, incorporating harmonic relationships as dependencies under a predetermined prime-limit constraining numerical complexity of frequency ratios. The system includes an inference module connected to the context input module and learning processor, configured to convert input notes from equal-tempered tuning to corresponding natural tuning frequencies based on identified patterns and musical context information, generating output comprising natural tuning frequencies expressed as whole number relationships.

The invention discloses a direct-current magnetic bias fault diagnosis method and related device for vibration signals of a high-frequency transformer, and belongs to the technical field of direct-current magnetic bias fault diagnosis. The method comprises the following steps: collecting vibration signals of the surface of a clamping piece of the high-frequency transformer under different working conditions; performing fast Fourier transform on the vibration signal to obtain the amplitude of the vibration signal under each frequency; calculating the frequency proportion of the vibration signal, the odd-even harmonic ratio of the vibration signal and the vibration entropy of the vibration signal; calculating a direct current bias judgment characteristic value based on the frequency proportion, the odd-even harmonic ratio and the vibration entropy; and comparing the direct-current bias judgment characteristic value with a preset threshold value, and judging the direct-current bias state of the high-frequency transformer. According to the method, the complexity of detection and maintenance is reduced, online monitoring can be realized under the normal operation condition of the transformer, potential fault hidden dangers can be found in advance, the defects of magnetostriction and vibration monitoring caused by direct current magnetic bias in the prior art are overcome, and the feasibility of direct current magnetic bias hidden danger detection is improved.

The invention discloses a mobile measurement trolley based on bridge frequency measurement and damping tuning, which comprises a system pre-starting and parameter initialization stage: a first pass pre-scanning and parameter coarse identification stage: in the stage, the trolley passes through a bridge at a constant speed, collects a vibration signal, position information and a suspension state, and extracts a bridge fundamental frequency estimated value through FFT analysis; in the damping parameter dynamic tuning stage, tuning is carried out based on the fixed point principle, the optimal frequency ratio and the optimal damping ratio are calculated, and the damping parameters are adjusted; a secondary passing fine measurement and verification stage: performing high-precision data acquisition on the trolley through the bridge again in the stage, calculating a difference value, and judging the frequency stability; in the cycle tuning and convergence judgment stage, when the frequency change rate is larger than a threshold value, the mobile measurement trolley starts a new round of tuning-measurement cycle until the requirement is met, and the technical obstacles that a traditional passive mass damper is limited by space and weight, insufficient in controllability and the like in mobile vehicle scene application are overcome.

The invention relates to the technical field of electromagnetic shielding, and provides a variable-frequency-ratio metasurface absorber which is characterized in that a first metal sheet and a second metal sheet are arranged on the upper surface and the lower surface of a substrate respectively, the second metal sheet is grounded, and the first metal sheet receives electromagnetic waves and is connected with an absorption circuit so as to selectively absorb target electromagnetic waves through the absorption circuit; the first metal sheet is provided with a fishbone-shaped groove, the fishbone-shaped groove comprises a first main groove, a second main groove and a plurality of secondary grooves, and the first metal sheet is symmetrical in the transverse direction and the longitudinal direction; the second main grooves are arranged on two sides of the first main groove and are separated from the first main groove through the connecting branches. The first main groove and the secondary groove are isolated through the second main groove and the connecting branch knot, resonance interference between the first main groove and the secondary groove is reduced, and therefore when the corresponding target absorption frequency is adjusted by adjusting the length of the secondary groove, interference on the absorption frequency corresponding to the first main groove can be reduced, and the absorption efficiency of the device is improved. And the design cost of absorption frequency adjustment is reduced.

The invention discloses a method for judging internal instability of a large-span suspension bridge, which belongs to the technical field of bridge engineering and comprises the following steps of: 1, acquiring section parameters and modal parameters of a bridge, and constructing a vertical-torsional coupling dynamic model of a main cable-suspender-main beam system of the large-span suspension bridge; 2, on the basis of bridge section parameters and modal parameters, vertical modal inherent frequencies of all orders and torsional modal inherent frequencies of all orders are calculated; 3, for the combination of any one vertical mode and any one torsional mode, calculating a frequency ratio, and judging whether the frequency ratio falls into a sensitive frequency ratio range of internal instability or not; 4, if the frequency ratio falls into a sensitive frequency ratio range, calculating a critical span interval corresponding to the modal pair according to an internal instability condition; 5, based on the critical span interval of each modal pair, establishing a segmented envelope line of internal instability; and 6, judging the internal instability risk of the bridge according to the subsection envelope line indexes. By the adoption of the method, the vibration risk of the large-span suspension bridge under the non-external resonance condition can be effectively recognized.

This invention discloses a vibration control method for lifting a target object during construction. The method includes: measuring the height of the target object at any given time and determining the mass of a damping box; determining the optimal frequency ratio and optimal damping ratio of a damping device (TMD) and a load-bearing structure based on the mass of the damping box; the TMD including a damping box and a lifting device for lifting the damping box; and the load-bearing structure including the target object being lifted and a distance measuring device for measuring the height of the target object. Under the constraints of the optimal frequency ratio and optimal damping ratio, determining the suspension length of the damping box based on the height of the target object; and lifting the damping box according to the suspension length, such that at time t, the suspension length of the damping box matches the height of the target object, thereby eliminating or reducing the vibration impact. This invention can eliminate or reduce the vibration caused by wind loads on the target object during the lifting process, improving construction safety.

The invention discloses an electric pole burial depth measuring method, system and device based on knocking vibration echoes and a medium, and the method comprises the steps: applying knocking excitation to a part, exposed out of the ground, of an electric pole, and collecting a vibration response signal excited by the knocking excitation; performing spectral analysis to obtain fundamental frequency information and high-order frequency information; calculating to obtain frequency ratio information; and pre-storing frequency ratio-burial depth mapping relation information, matching the frequency ratio information with the pre-stored frequency ratio-burial depth mapping relation information, and outputting an electric pole burial depth result. Through an innovative algorithm based on frequency ratio information, the defects that a traditional method depends on archives and is low in efficiency and poor in precision are overcome; standardized excitation and vibration response signal acquisition, spectrum analysis and query output are combined, the objectivity, reliability and engineering practicability of detection are improved, the method is suitable for large-scale field general survey, and rapid, accurate and lossless burial depth measurement under the condition that the total length of the electric pole is unknown is achieved.