8 results about "Frequency ratio" patented technology

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 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.

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.

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 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.

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.