61 results about "Natural mode" patented technology

The invention discloses a simulated spacecraft wallboard structure fluttering/vibrating control device and method. The device comprises a flexible board body, a mechanical clamping device, a signal generator, a computer, an A/D (analog/digital) conversion data collecting card, a D/A conversion card, a piezoelectric ceramic drive power source, an acceleration sensor, piezoelectric ceramic piece sensors and piezoelectric ceramic piece drive devices. The flexible board is fixed through two ends of the mechanical clamping device, a plurality of piezoelectric ceramic piece sensors and piezoelectric ceramic piece drive devices are adhered on the flexible board structure and provided with the acceleration sensor. The signal generator stimulates a natural mode of the flexible board through a piezoelectric ceramic piece stimulation drive device and the piezoelectric ceramic drive power source, when the sensors detect a vibrating signal of the flexible board, an active control algorithm is operated, the controlled quantity is applied onto the piezoelectric ceramic piece control drive device through the piezoelectric ceramic drive power source, so that the vibration of the flexible two-end fixed supporting plate can be actively controlled.

The invention discloses a method for improving respiratory rate detection accuracy, comprising the following steps of: preprocessing respiratory data by utilizing high pass and low pass filtering; then carrying out empirical mode decomposition on the preprocessed respiratory data; subsequently, selecting a natural mode function obtained by the decomposition according to the physiological feature of a respiratory signal; then carrying out choking judgment on the obtained natural mode function by utilizing a method of getting the absolute value and solving the average; and if the choking judgment condition is not satisfied, figuring out the respiratory rate at the time by utilizing a wave form method or a frequency spectrum method. By adopting the technical scheme, the respiratory signal can be effectively extracted from respiratory waves of dysphoria interference and heartbeat interference. The method of the empirical mode decomposition effectively overcomes the defect that the respiratory signal containing the interference is directly processed by the wave form method and the frequency spectrum method, and finally, the weighted average of the historical respiratory rate is introduced, and thereby, the interference resistance of respiratory detection can be improved to make the respiratory rate calculation stable and reliable.

The invention relates to an in-plane-control-based active vibration control method for a wrinkled film. On the basis of the analysis on the influence on dynamic characteristics of a film structure bya wrinkle form, a dynamic model of a wrinkled film is established; according to a modal superposition method, a space vector based on a natural mode of vibration is obtained and dynamic models of thewrinkled film under different loads are established; condensation polymerization is carried out on the dynamic models according to contributions to system vibration deformation by all orders of modes,so that a control-oriented film structural dynamic model is established; and with a model reference adaptive controller, a PID-MRAC control method based on in-plane-control multi-model switching is proposed. According to the method provided by the invention, no actuator needs to be pasted on the surface of the film; the out-of-plane vibration of the film is suppressed effectively; the characteristics of the film are not affected; the high stability of the film structure is ensured; and compared with the conventional PID control method, the in-plane-control-based active vibration control method enables the vibration time to be shortened by about 39.7%.

The invention discloses a seismic fluid prediction method based on VMD and TK energy operators. The method comprises the following steps: S1, performing variational mode decomposition on a seismic signal to obtain a set of modal components that reflect a natural mode of vibration inside the seismic signal and have an instantaneous frequency with real physical meaning; S2, getting TK energy spectrums of each modal component by using the TK energy operators to obtain more accurate energy distribution on a signal time frequency; and S3, performing effective and accurate seismic fluid prediction by searching fluid characteristics of ''enhanced low frequency energy and attenuated high frequency energy'' of oil and gas contained in the reservoir. The seismic fluid prediction method based on VMDand TK energy operators combines the variational mode decomposition with the TK energy operators, which has stronger identification for the fluid-containing characteristics of the reservoir, and can effectively improve the accuracy of seismic fluid prediction.

The invention relates to a method for removing noises of a wind profile radar based on Hilbert-Huang transform. Based on a noise removing processor of the wind profile radar, the processor comprises an improved empirical mode decomposition module, a Hilbert transform module and a follow-up signal processing module. The method comprises the following steps that: 1) the noise removing processor of the wind profile radar receives an echo signal and utilizes the improved empirical mode decomposition module to obtain a series of natural mode function components of the echo signal; 2) the Hilbert transform is performed on each natural mode function component through the Hilbert transform module so as to obtain an energy spectrum value of the original signal; and 3) the follow-up signal processing module transforms the energy spectrum value of the original signal to obtain wind profile radar data after removing the noises. The invention has the following beneficial effects: the method has good adaptability, can obviously remove non-stationary interference, such as noises, and can especially and effectively remove the aliasing influence and the boundary effect of the adjacent frequencies.

Method and sensor arrangement for determining a contact force vector acting on a rolling element bearing (1) in operation. Sensor signals are received from a plurality of sensors (8) measuring performance characteristics of the rolling element bearing (1). The received sensor signals are processed to determine the contact force vector. The plurality of sensors (8) are arranged to measure a bearing component deformation, and the step of processing comprises the step of determining the contact force vector using an inverse transformation of a finite element analysis model which describes the rolling element bearing (1). The finite element analysis model is simplified using at least one generalised mode shape, the at least one generalised mode shape being a mathematical description of a natural mode deformation of a component of the rolling element bearing (1), such as the inner or outer ring (5, 6).

An apparatus and method for suspending a stator core (100) in an electric generator upon a foundation (206), where two natural modes of vibration, including known second and third modes, are excited in the core, each mode having four loops and four nodes displaced 45 degrees between the second and third modes. A non-rigid connection (212) connects a yoke to the foundation, and two connection members connect the yoke to the stator core at opposite sides of the non-rigid connection. The two connection points (210a,b) are located at adjacent loops of one of the second and third vibration modes. By this arrangement, radial deflections of the stator core at the respective connection points are transferred into a rocking movement of the yoke around the non-rigid connection. Thereby, vibrations transferred to the foundation are considerably reduced during operation.

The invention discloses a micro-motion test method and system for structural damage detection of a civil engineering wallboard. The micro-motion test method comprises the following steps: a plurality of detectors are arranged on the surface of the wallboard according to the masonry, damage and other characteristics of a structure, and micro-motion signals are acquired through the detectors and recording equipment; the natural frequency and the natural mode of vibration of the structure are acquired through mathematical analysis; a finite element model (finite difference model) of the structure is built and perfected for eigenvalue computation so as to acquire the natural frequency, the natural mode of vibration and other dynamic response parameters; and the natural frequencies and the natural modes of vibration of a computation module and an actual measurement structure are compared to evaluate the break position and the break value (rigidity loss) of the response and position and quantify the damage. The invention further provides a corresponding system. The method and system have the advantages of simple equipment, high efficiency, no structural damage, strict transactional analysis, high precision of the analytic method, and no influence from the structural damage degree and complexity. Therefore, the invention provides a brand-new method for structural damage detection of the civil engineering.

Vibrations due to excitation of the natural modes of an aircraft's body are suppressed by an active multi-axis modal suppression system. Dedicated sensors are positioned in the aircraft at optimal locations for sensing modal induced vibrations. The sensor produced signals are processed through control logic which, in response thereto, and in response to aircraft inertial, velocity and altitude related signals produces output control signals. The control signals effect control surface deployment creating forces to suppress the natural mode induced vibrations on multiple geometric axis's. More particularly, symmetric and anti-symmetric control surface deployments are used on one or more geometric axis's to damp lateral, longitudinal, vertical and most importantly torsional vibrational modes.

The eye is positioned relative to a detection device in such a manner as to co-operate with the device to form a Fabry-Perot cavity having a main optical axis and comprising two opposite reflecting faces on the main optical axis, one of these two faces being constituted by a stationary reflecting element and the other being formed by the cornea of the eye. An incident laser beam is injected into said cavity so as to be centered on the main optical axis of the Fabry-Perot cavity, the cornea is aligned laterally and longitudinally relative to the main optical axis in such a manner as to obtain longitudinal interference between the go and the return laser beams reflected between the two reflecting faces of the cavity, and an optoelectronic detector is used to detect the intensity I of said interference as a function of time. The invention is applicable to measuring intraocular pressure.

The invention discloses a detection method and a detection system of a generator sub-synchronous resonance generator terminal damping controller. The detection method includes that electrical power system simulation environment, a 12-chain cascade H-bridge voltage source converter model and a boosting transformer of the 12-chain cascade H-bridge voltage source converter model are established, the electrical power system simulation environment provides electric signals for a control cabinet of the generator sub-synchronous resonance generator terminal damping controller, the control cabinet of the generator sub-synchronous resonance generator terminal damping controller generates window signals according to the electric signals, the window signals controls an insulated gate bipolar translator (IGBT) of each bridge of the 12-chain cascade H-bridge voltage source converter model to be powered on or powered off, a restraining sub-synchronous resonance damping current is generated and injected into a generator terminal of a generator model through the boosting transformer model, disturbance is arranged so as to stimulate the electrical power system simulation environment to generate sub-synchronous resonance of self natural mode of vibration, and the restraining effect of the sub-synchronous resonance of the restraining sub-synchronous resonance damping current to the self natural mode of vibration of the electrical power system simulation environment is detected.

The invention relates to the field of safety of blasting vibration and aims to provide a safety evaluation method and system of blasting vibration based on energy input. The system comprises a blasting vibration safety evaluation module built-in a computer system. The method comprises the steps of: performing empirical mode decomposition for a signal of blasting vibration, extracting a function component of natural mode of vibration of a blasting vibration signal, performing Hilbert conversion for the function of natural mode of vibration of the blasting vibration signal and calculating the Hilbert instantaneous energy value of the signal; integrating the Hilbert instantaneous energy value and obtaining a total input energy TIE value; comparing the total input energy TIE value as a safety evaluation index of blasting vibration with a critical TIE index of a protected object in a safety evaluation index library module of blasting vibration to obtain the safety indication information. By using the TIE as the safety evaluation index of blasting vibration, the invention can perform more explicit and concise quantificational description for factors such as basic frequency, duration and the like and evaluate the influence of the blasting vibration more accurately, thereby avoiding the erroneous judgment of blasting vibration damage.

The invention discloses an electroencephalogram characteristic extracting method based on DWT and EMD integrating CSP. The method comprises the steps of using obtained electroencephalograms as a training set and a testing set and preprocessing the electroencephalograms in channels selected in the training set and the testing set respectively; conducting wavelet decomposition on the electroencephalograms after being preprocessed to obtain sub-band signals after wavelet decomposition and selecting sub-band signals within a set frequency range; conducting empirical mode decomposition on the selected sub-band signals to obtain a natural mode function to obtain reconstructed signals; merging IMF components in the sub-band signals into a matrix, conducting public space mode decomposition on thematrix to obtain a space filter and obtaining characteristic vectors through the space filter; utilizing a support vector machine to conduct characteristic classification training on the characteristic vectors and inputting the preprocessed testing set into the trained support vector machine to classify characteristics to obtain a characteristic classification result. The problem of CSP is input many times and frequency domain information is lacked can be effectively solved.

The invention discloses a double-ring reducer radiation noise numerical value simulation and study method. The method comprises the steps of firstly, establishing a power finite element analysis model of a reducer transmission system and structural system; secondly, applying ANSYS software to conduct natural mode of vibration and dynamic response numerical value simulation on a double-ring reducer; thirdly, with vibration displacement being a boundary condition, establishing an acoustic boundary element analysis model of a reducer case body; fourthly, using a direct boundary element method to calculate radiation noise of a case body surface sound pressure and field point in SYSNOISE software; fifthly, utilizing a transmission system test stand to conduct a vibration accelerated speed and radiation noise test on the double-ring reducer. According to the double-ring reducer radiation noise numerical value simulation and study method, gear internal dynamic incentive and an inertial incentive of an annular plate generated by a gear rigidity incentive, an error incentive and a meshing impact incentive are taken into comprehensive consideration, and a method with the combination of a finite element and a boundary element is adopted to conduct reducer dynamic response and numerical value simulation of radiation noise.

A bright line plot processing method of plotting a blight line which starts from the pixel at a bright point in an image to be processed is provided where a more natural mode of the cross filter effect can be applied to any digital photographic image. The bright line plot processing method comprises: a first bright line plotting step for generating an image of the bright line using a predetermined bright line definition format; a second bright line plotting step for generating data of the pixel at the bright point; a third bright line plotting step of generating data of each pixel for the bright line from the pixel data produced by attenuating the data of the pixel at the bright point at a predetermined attenuation rate along the lengthwise and/or widthwise direction of the bright line and the pixel data of the image to be processed; and a fourth bright line plotting step of plotting the data of the pixels for the bright line on the image to be processed.

The invention provides a longitudinal double-mode SAW filter that has a large reflection coefficient by the electrode conductors and having flat pass band characteristics. In the longitudinal double-mode SAW filter, nearly all of higher-order natural mode oscillation displacements A0, S1 and A1 are made present in the first and second interdigital transducer regions. An electrode finger phase weighting is formed to correspond to a BPSK sign where a phase sign changes into 0 or π at a polarity-changing point on an electrode charge distribution function Q(x) that generates on the electrode due to natural modes of oscillation. A single pair of natural modes, which exist stationary in the direction X of propagation of the surface acoustic waves that are utilized, is selected. A symmetrical mode charge distribution (Q(x), −Q(x)) and an obliquely symmetrical mode charge distribution (Q(x), Q(x)) are generated in order to correspond to the regions of IDT1 and IDT2. The PTNG in the control IDT3 region is set to be in the range of 1.02 to 1.04 so as to couple the two together.

The invention relates to a Tibetan phrase input method, which mainly utilizes valid combination of Tibetan etymons and vowel characters to form codes, is suitable for various currently popular Tibetan input codes or keyboard layout, has the characteristics of few repeated codes, easy implementation, easy establishment and expansion of word stocks and the like, meets the natural mode of thinking of Tibetan writing, and can be understood and used easily.

The invention discloses a vibration sensor-based vehicle recognition method, and aims at automatically recognizing vehicle types. The method comprises the following steps of: receiving a road surfacevibration signal caused by a vehicle by utilizing a vibration sensor; carrying out empirical mode decomposition on the acquired vibration signal to obtain a group of natural mode functions; multiplying the natural mode functions by different weights; summing the fixed mode functions to form a new signal; carrying out power spectrum analysis on the newly generated signal so as to obtain an MFCC feature vector; and training a BP neural network to obtain a new classifier for recognizing vehicle categories. The vehicle recognition method disclosed by the invention is strong in robustness and highin recognition rate, can be used for military vehicle classification and civil intelligent traffic systems, and has a broad prospect.

The invention relates to the technical field of compressors, in particular to a liquid accumulator for a compressor. The liquid accumulator is provided with a cylinder body, one or multiple vibrationattenuation parts are arranged in the cylinder, through holes allowing fluid to pass through are formed in the vibration attenuation parts, the vibration attenuation parts are arranged in the liquid accumulator, vibration of the liquid accumulator can be restrained, meanwhile, the natural mode of the liquid accumulator can be changed, and the phenomenon that vibration of the compressor is transmitted to the liquid accumulator, the natural mode of the liquid accumulator is motivated, and abnormal noise is caused can be avoided.