28 results about "Super low frequency" patented technology

This invention relates to a method for measuring the stability margin of a constant-temperature hot-wire anemometer based on in-situ open-loop frequency characteristics, belonging to the field of fluid measurement and automatic control technology. The method disclosed in this invention includes the following steps: S1. Connecting an ultra-low frequency low-pass filter to the closed-loop circuit to form an in-situ open-loop system with a DC closed loop and an AC open loop; S2. Injecting a sweep frequency excitation signal E at the bias circuit. stimu And measure the output response E of the amplifier circuit. a By comparing the amplitude ratio and phase difference of the two, the open-loop frequency response G of the system under actual operating conditions of the hot wire is obtained. open (jω); S3. According to G open (jω) Obtain the phase margin of the system and determine its stability. This invention proposes a new method for measuring the stability margin of a constant-temperature hot-wire anemometer, transforming the complex system stability problem into a measurable and analyzable open-loop frequency characteristic stability margin problem, providing a direct and reliable engineering basis for the circuit design of constant-temperature hot-wire anemometers.

A kind of atomic gyroscope pumping rate stable composite control method based on phase reshaping extended state observer and power approaching sliding mode control.Aiming at the problems that standard linear extended state observer has steady-state estimation error under the action of ramp disturbance, disturbance estimation phase lag and it is difficult to balance between observation bandwidth improvement and noise sensitivity, a composite corrector composed of lead network and lag network is cascaded at the output end of disturbance estimation of extended state observer, the disturbance estimation channel is shaped in frequency domain, phase lead is provided in mid-frequency band to reduce compensation delay, amplitude lag characteristic is used to suppress high-frequency noise, and parameter constraint design is used to realize zero-error estimation of ramp disturbance;At the same time, a power approaching sliding mode controller is constructed to improve the adaptability to the nonlinear, internal and external coupling and parameter uncertainty of atomic gyroscope system, and the phase reshaping extended state observer is combined to effectively estimate and feed forward compensate the lumped disturbance, so as to improve the stability and accuracy of pumping rate control.The present application can balance dynamic anti-disturbance performance, steady-state control accuracy, convergence speed and noise robustness without significantly improving the observation bandwidth, and is suitable for atomic gyroscope precision control system affected by ultra-low frequency slowly varying disturbance.

The application provides a cable insulation aging evaluation method based on high-voltage frequency domain dielectric response characteristic quantity, under the condition that the insulation electric field intensity is 0.5kV / mm-1kV / mm, an ultralow frequency sweep test signal is applied to the measured cable under three different voltages, and the dielectric loss tangent value frequency domain response curve corresponding to each voltage level is obtained; at least two dielectric characteristic quantities are calculated based on the frequency domain response curve, the dielectric characteristic quantities include a first characteristic quantity representing the discrete degree of the dielectric loss tangent value under different voltages, and a second characteristic quantity representing the frequency domain integral characteristic of the dielectric loss tangent value under the highest test voltage; based on a preset correlation evaluation model taking the cable insulation mechanical performance aging index as a benchmark, the insulation health state score of the measured cable is calculated by combining the dielectric characteristic quantities, and the insulation aging state is determined according to the health state score.

The application discloses a torsional negative stiffness vibration isolation device based on pre-tensioned springs and belongs to the technical field of vibration isolation devices.The vibration isolation device can normally transmit the rated torsional motion of a system, reduces the torsional dynamic stiffness of the system, lowers the natural frequency, realizes the torsional vibration isolation of shaft system components under low-frequency and ultralow-frequency bands, and has a good vibration isolation effect.Two ends of two connecting rod devices are connected in a hinged manner on an inner part and corresponding sliding blocks respectively, the two sliding blocks are limited in displacement directions through sliding grooves fixed on the inner side of an outer part, and elastic elements generate acting forces on the two sliding blocks and apply torsional moments on the inner part through the two connecting rod devices.The application introduces a negative stiffness device, reduces the torsional dynamic stiffness of a shaft system structure, lowers the natural frequency of the system in the torsional direction, and realizes the vibration isolation function under low-frequency and ultralow-frequency bands.

The application discloses a primary active ultra-low frequency vertical vibration isolation system, comprising a passive vibration isolation platform, a load, a vibration sensor, a driver and a control circuit, wherein the passive vibration isolation platform is internally provided with a horizontal limiting mechanism, the horizontal limiting mechanism is any mechanism capable of limiting three rotational degrees of freedom and two degrees of freedom of translation in a horizontal plane of an object, and only has a single degree of freedom of vertical translation. The system has the characteristics of low complexity and good long-term stability, the scheme for realizing horizontal limiting through mechanical design is simpler, and is helpful to improving the stability of the active vibration isolation system. Compared with the prior art, the application does not need more cost, and the efficiency is not obviously reduced.

A method for detecting and adaptively compensating for ultra-low frequency weak vibrations in a MEMS accelerometer includes: a multi-channel parallel coherent modulation and demodulation module acquiring differential capacitance signals of the sensitive units in the MEMS accelerometer through n parallel coherent detection links, and then synchronously modulating and coherently demodulating the differential capacitance signals to obtain n baseband signals; an adaptive weighted fusion module evaluating the signal-to-noise ratio (SNR) of each baseband signal, and then weighting and fusing the n baseband signals using the square of the SNR as a weighting coefficient to obtain a fused signal; a dynamic temperature drift compensation module performing temperature drift compensation on the fused signal to obtain a compensated signal; and a variational mode decomposition adaptive filtering module performing adaptive filtering on the compensated signal to output the final acceleration signal. The effect is to improve the detection of ultra-low frequency weak vibrations in a MEMS accelerometer and enhance the accuracy of wide-temperature-range dynamic temperature drift compensation.

This invention relates to a stability measurement method for a constant-temperature hot-wire anemometer based on the identification of equivalent pure delay element parameters, belonging to the field of fluid measurement and automatic control technology. The method disclosed in this invention includes the following steps: S1. Connecting an ultra-low frequency low-pass filter to the closed-loop circuit of the system to form an in-situ open-loop system with a DC closed loop and an AC open loop; S2. Injecting a sweep frequency excitation signal E at the bias circuit. stimu And measure the output response E of the amplifier circuit. a By comparing the amplitude ratio and phase difference of the two, the open-loop frequency response G of the system under actual operating conditions of the hot wire is obtained. open (jω); S3. Using the preset transfer function model G * open (s) Fit the measured frequency response to identify the pure delay element G introduced by non-ideal factors such as circuit distributed parameters and device hysteresis. delay (s), and uses its parameter b to quantify the non-ideal factors of the system. This invention realizes in-situ measurement of system stability, quantifies non-ideal factors into measurable parameters, and provides a reliable basis for system stability analysis and circuit design.

This invention discloses an electromagnetic generator and its operating method for converting ultra-low frequency vibration energy, belonging to the field of vibration energy harvesting and micro-power generation technology. It includes a base, an electromagnetic induction component, an inner rotor, a transmission device, and a top cover. The electromagnetic induction component has a central hole, within which the inner rotor is housed. The electromagnetic induction component includes an outer rotor and a stator, arranged vertically opposite each other. The outer rotor has a magnet, and the stator has a coil. The base is connected to the bottom of the inner rotor via a thrust bearing, the middle of the inner rotor is connected to the top cover via a linear bearing, and the top of the inner rotor is connected to the top cover via the transmission device. The inner rotor is also connected to the outer rotor via a one-way bearing. The base is also connected to the top cover via a linear bearing, and a spring is provided between the top cover and the linear bearing. This invention can harvest ultra-low frequency vibration energy from the environment, achieving higher energy harvesting efficiency compared to traditional electromagnetic energy harvesters.

Disclosed is a method for predicting time-varying effect of surface ultra-low frequency micro-vibration of confluence water area alluvial site, comprising: 1) signal collection and pretreatment, including collecting vibration signals in the range of 0.05-50 Hz at the site test point, retaining vibration signals in the range of 0.05-20 Hz and pretreating the signals; 2) water area vibration feature extraction, including performing EMD decomposition on the pretreated information x(t) to obtain IMF components, and screening and separating ultra-low frequency water area vibration signals a water (t) from the IMF; 3) dynamic coupling of time-varying factors, including nonlinearly coupling the ultra-low frequency water area vibration signals a water (t) with three factors to construct a preliminary prediction function a(t) of the ultra-low frequency vibration amplitude: a(t) = k·(θ(t)·β(t)·γ(t)) N ; and 4) modifying the preliminary prediction function to obtain an ultra-low frequency micro-vibration prediction formula a(x, y, t) = TF mod (t)·a(t), wherein TF mod (t) is a modified transfer function.

The application belongs to the technical field of pest detection, and particularly relates to a stored grain pest detection method based on HPSD-DDF, and specific step processes of the stored grain pest detection method are as follows: obtaining a stored grain pest image in a pest trapping trap and performing data preprocessing, data enhancement and data labeling to obtain a preprocessed image data set; in the application, DSTEM is introduced to enhance and process small target features in a frequency domain, and the detection capability of a model for small targets of stored grain pests is effectively improved. The DSTEM module adaptively processes four frequency bands of ultralow frequency, low frequency, medium frequency and high frequency through MFB, and the high-frequency boundary information of small targets is enhanced in a targeted manner; meanwhile, EEB adopts a multi-directional edge detection operator to further strengthen target boundary features. On a stored grain pest data set, compared with a baseline model, the AP 50:95 of small targets is improved from 28.8% to 32.1%, with an increase of 3.3 percentage points, which verifies the effectiveness of the DSTEM module on small target detection.

This invention discloses a closed-type stiffness nonlinear disc structure, comprising an upper cover, a lower cover, a support cylinder, and a spring. The upper and lower covers have identical disc-shaped structures, each including a base plate, an elastomer, and a flange ring. The openings of the upper and lower covers face each other, and their flange rings are respectively sealed and fixed to both ends of the support cylinder. The spring is disposed between the upper and lower covers. This invention can directly bear external loads as a support structure, or it can be placed inside an air spring or hydraulic support. It can achieve ultra-low frequency support under various loads, and has the advantages of high load-bearing capacity, compactness, and high reliability. It is suitable for ultra-low frequency vibration control in fields such as precision instruments, aerospace, and shipbuilding.

This invention relates to a method for bandwidth evaluation of a constant-temperature hot-wire anemometer based on in-situ open-loop frequency characteristics, belonging to the field of fluid measurement and automatic control technology. The method disclosed in this invention includes the following steps: S1. Connecting an ultra-low frequency low-pass filter to the closed-loop circuit to form an in-situ open-loop system with a DC closed loop and an AC open loop; S2. Injecting a sweep frequency excitation signal E at the bias circuit. stimu And measure the output response E of the hot wire voltage. w By comparing the amplitude ratio and phase difference of the two, the frequency characteristic G is obtained. * gain (jω); S3. Based on the frequency characteristic G * gain The amplitude-frequency response curve of (jω) is used to determine the corner frequency f when its gain drops to -3dB below the DC gain. * c With this transition frequency f * c This invention serves as an estimate of the bandwidth of the constant-temperature hot-wire anemometer. It enables direct measurement and evaluation of the dynamic performance of the constant-temperature hot-wire anemometer in the frequency domain, allowing testing to be completed without changing the bias voltage and DC operating point. This accurately and conveniently reflects the system bandwidth of the hot wire under actual operating conditions.

The application provides a passive quasi-zero stiffness vibration isolation unit and track system for a floating slab track, wherein the vibration isolation unit comprises a shell with a support disc, and an internal positive stiffness mechanism, a negative stiffness mechanism and a mechanical coupling structure; the positive stiffness mechanism comprises a mechanical spring and a positive stiffness gas spring arranged in parallel, the mechanical spring provides a main static load path independent of gas pressure and generates a restoring force that increases with displacement when compressed; the negative stiffness mechanism comprises a plurality of negative stiffness gas springs uniformly distributed around the positive stiffness mechanism; the mechanical coupling structure is used to connect the positive stiffness mechanism and the negative stiffness mechanism, and the negative stiffness gas springs are stretched under the driving of the mechanical coupling structure to generate a restoring force that decreases with displacement; the two compensate for each other within a predetermined working displacement, so that the vibration isolation unit presents a quasi-zero stiffness characteristic near the equilibrium position. The application has a simple, stable and reliable structure, is a passive design, can maintain high static load capacity, and effectively attenuates low-frequency and ultra-low-frequency vibrations.

A magnetic ring type high static low dynamic stiffness vibration isolator capable of adapting to various working conditions and a use method thereof belong to the field of vibration isolation and noise reduction equipment and are composed of a support assembly, a permanent magnet positive stiffness assembly, a disc spring negative stiffness assembly and a bearing mechanism. The support assembly is a hollow cylindrical structure and can shield the influence of a magnetic field on the external environment. The permanent magnet positive and negative stiffness assemblies respectively provide positive and negative stiffness for the vibration isolator, wherein the relative movement between the inner and outer magnetic groups in the positive stiffness assembly generates a magnetic force to provide a vertical bearing capacity. The bearing mechanism supports the vibration-isolated object on the object table. The vibration isolator can be applied to various vibration working conditions, has the effects of reducing the vibration amplitude from the base to the vibration-isolated object and providing a supporting action, and the vibration-isolated object needs to be placed horizontally or fixed on the object table during use. The vibration isolator can adapt to changes in the load working condition by adjusting the relative position between the magnets, has good low-frequency and ultra-low-frequency vibration isolation effect, a wide vibration isolation frequency band and stable working performance.

This application relates to the field of vibration reduction technology for long-span bridges, and provides a vertical ultra-low frequency stacked spring viscous damping adjustable inertial capacity tuned mass vibration damper. The damper includes a mass block, a helical steel spring, a damping device, a transverse support, a sleeve, a ball screw, and a flywheel. The helical steel spring is located between the horizontal support and the base, and the damping device is located between the mass block and the base. The sleeve is rotatable and located on the transverse support, with an embedded ball screw nut. The ball screw screw passes vertically through the ball screw nut and is connected to the mass block. A base plate is located on the upper part of the sleeve. The flywheel is composed of multiple sets of mass discs of different thicknesses stacked together. The uppermost mass disc has a replaceable micro-block for frequency fine-tuning. This application can progressively reduce the operating frequency of the TMD (tunable damper) through the stacked spring and inertial capacity mass, achieving ultra-low frequency control below 0.1Hz. It has advantages such as low inertial capacity mass requirement, flexible adjustment, high frequency adjustment accuracy, low starting resistance, convenient damping ratio adjustment, and compact structural layout.

The application discloses an ultra-low frequency polarity adaptive circuit structure and an operation method thereof. The ultra-low frequency polarity adaptive circuit structure comprises: an ultra-low frequency signal module, which is provided with a topology structure of a polarity circuit, and circuit elements of the ultra-low frequency signal module have a nanometer order characteristic size; a core structure module, which comprises a bipolar transistor array and a quantum effect compensation unit, and the bipolar transistor array and the quantum effect compensation unit are respectively used for signal compensation and stability control; a simulation experiment module, which is used for constructing a circuit simulation model and testing circuit performance in a 0.1-10 Hz frequency band; and an improved Gilbert module, wherein input impedance of the improved Gilbert module is not less than 10 12 Ω, an equivalent noise voltage of the improved Gilbert module is not greater than 5 nV / √Hz at a 1 Hz frequency, and a temperature drift coefficient of the improved Gilbert module is less than 0.1 μV / ℃.

This invention discloses a high-bandwidth, notch-free hybrid magnetocurrent sensor circuit, comprising a low-frequency path, a high-frequency path, a differential amplifier, a compensation path, and a dual-to-single converter. The low-frequency path utilizes a Hall effect sensor and auxiliary bias circuitry to detect the low-frequency component of the current, and simultaneously suppresses sensitivity drift and common-mode drift by replicating a negative temperature coefficient voltage. In the high-frequency path, the integrator consists of two paths with the same gain-bandwidth product but different low-frequency gains, and gain flatness is improved through compensation technology. The servo loop employs active capacitor amplification technology, using small-area resistors and capacitors to achieve ultra-low-frequency poles. The outputs of the high- and low-frequency paths are combined via a differential amplifier and then pass through a subtractor and a high-pass filter to form a compensation path for eliminating chopper ripple. Finally, the signals are converged in the dual-to-single converter to obtain a notch-free broadband output. This invention simultaneously solves problems such as chopper notch, gain unevenness caused by pole-zero mismatch, and the use of large-area passive components.

The application relates to a nuclear power waste water treatment system and belongs to the technical field of nuclear power. The system comprises a waste water pump, an ion exchange column, a water inlet of the ion exchange column connected with the waste water pump and used for removing radioactive nuclide ions in inflowing waste water, a special frequency electromagnetic wave generator installed around the ion exchange column, a special frequency excitation device electrically connected with the special frequency electromagnetic wave generator and used for generating an ultra-low frequency time-varying pulse electromagnetic wave, and a control module connected with the special frequency excitation device and used for controlling waveform parameters of the ultra-low frequency time-varying pulse electromagnetic wave. In this way, the ion exchange rate and capacity can be improved, resin pollution can be inhibited, and the service life can be prolonged.

The present application relates to the field of intelligent operation and maintenance of hydroelectric power generation and active acoustic control, and discloses a method and system for intelligent acoustic impedance matching of a hydraulic turbine based on deep learning. The method comprises: collecting full-flow multi-source heterogeneous data to construct a sensor topology graph; using a spatiotemporal graph neural network for feedforward prediction of flow field excitation characteristics; using a multi-agent deep reinforcement learning algorithm with integrated physical constraint learning to make decisions on optimal configuration instructions; actively canceling intrinsic capacitance through a negative impedance converter, reconstructing the equivalent mechanical stiffness of the superstructure, and realizing real-time matching and noise reduction of acoustic impedance; and performing online fine-tuning based on residual noise feedback. The system comprises perception, reasoning, decision-making, execution and feedback optimization modules. The present application breaks through the physical limitations such as the Pashen limit through a non-Foster circuit, significantly enhances the suppression effect of ultra-low frequency below 100 Hz, effectively solves the control lag problem through feedforward logic, improves the stability of complex working conditions, and ensures the adaptability and robustness throughout the life cycle by combining physical constraints and incremental learning.

This application provides a method for outputting an electrical pulse of an ultra-long body-shaped harmonic, comprising: receiving a training mode input by a user or calling a preset training mode, and generating a control command; generating a carrier signal, an ultra-low frequency signal, and a low-frequency fundamental wave signal according to the control command; performing frequency matching, phase calibration, and timing latching on the ultra-low frequency signal and the low-frequency fundamental wave signal to form a harmonic control signal; modulating the carrier signal based on the harmonic control signal to form a modulated output signal; performing pass-pass-intercept-DC waveform filtering on the modulated output signal to form an electrical pulse of an ultra-long body-shaped harmonic; and outputting the electrical pulse. By generating a carrier, ultra-low frequency, and low-frequency fundamental wave signals, and modulating and outputting them after frequency matching, phase calibration, and timing latching, and then performing pass-pass-intercept-DC filtering, the output waveform is smooth, continuous, and rhythmic, which can form a long-term stable stimulus, effectively improving the harshness and discomfort of the electrical pulse output, and enhancing the stimulation effect and user comfort.

The application discloses a wind turbine blade vibration absorber based on quasi-zero stiffness, and belongs to the technical field of vibration control of large wind turbine blades. The wind turbine blade vibration absorber comprises a plurality of parallel quasi-zero stiffness mechanisms, the quasi-zero stiffness mechanisms are connected between wind turbine blade main beams through a plurality of cables, and the quasi-zero stiffness mechanisms and the wind turbine blade main beams are arranged in an inclined mode to form a vibration suppression array. The quasi-zero stiffness mechanism comprises a positive stiffness structure and a negative stiffness structure which are arranged in parallel. The positive stiffness structure comprises a coil spring, and the coil spring is used for providing positive stiffness. The negative stiffness structure comprises an air spring, and the air spring is used for providing negative stiffness. The wind turbine blade vibration absorber based on quasi-zero stiffness is adopted, quasi-zero stiffness is realized through parallel connection of the air spring and the coil spring, vibration control of low frequency or even ultra-low frequency of the blade is realized through reduction of the stiffness of the vibration absorber, and the vibration absorber is light in weight and high in reliability.

This invention provides an insulation testing device for high-voltage motors using a low-frequency injection method. By employing non-invasive injection of ultra-low frequency multi-frequency signals and identification using a fractional-order equivalent circuit model, it achieves a safe, online, and accurate assessment of the insulation status of high-voltage motors. This method completely avoids the cumbersome manual high-voltage operations of traditional testing, fundamentally eliminating the risk of electric shock, and supports testing of equipment in hot standby mode, improving operation and maintenance efficiency and safety. In particular, the introduced fractional-order model can more accurately fit the actual dielectric relaxation behavior of insulating materials. The identified parameters are extremely sensitive to degradation processes such as insulation aging and moisture absorption. Combined with the rich information obtained from multi-frequency sweeps, multi-dimensional characteristic quantities such as the model-predicted polarization index and dielectric loss spectrum can be calculated, thereby achieving more sensitive capture of early insulation defects and more accurate fault mode identification, providing strong technical support for predictive maintenance of high-voltage motors.

The present application relates to active vibration isolation control and sensor measurement technical field, specifically to a kind of three-axis ultra-low frequency feedforward measuring device based on piezoelectric sensor, including, buffer component is located in frame, mass block is located on buffer component, mass block two ends are equipped with connecting piece and limit block, and fixed plate is equipped on limit block, plastic column is inserted into each side wall of mass block, and plastic column penetrates connecting piece or frame, piezoelectric sensing unit is equipped on plastic column, two piezoelectric sensing units oppositely arranged are a group, the axis of two piezoelectric sensing units in same group coincides, the axis of three groups of piezoelectric sensing units is mutually orthogonal.Structure is compact, integration is high, utilize the quick response characteristics and low cross-coupling coefficient of piezoelectric material, effectively reduce the coupling interference of three-axis signal, improve the precision and timeliness of vibration signal acquisition, provide reliable sensing support for feedforward control of vibration isolation system, applied to precision instrument, aerospace and other fields of vibration isolation scene.

The application discloses a large-load full-permanent-magnetic electric-driving load-adjustable three-freedom-degree magnetic suspension vibration isolator, which comprises a bottom plate, a plurality of vertically arranged columns symmetrically distributed in a circle on the bottom plate, a vibration isolation unit arranged in each column, a sliding connection between the vibration isolation unit and the column, a placing platform arranged above the bottom plate, a hinge connection between the end of the placing platform and the corresponding column through a plurality of parallel connecting rods, and a space coupling of the stator and the mover permanent-magnetic array of the vibration isolation unit, so that the positive and negative stiffness mechanisms cooperatively generate a static suspension force in the load direction at the balance position, and the load upper limit is significantly improved. An adjusting mechanism is arranged in the support shaft, and the non-contact follow-up adjustment of the magnetic gap and the load adjustment are realized by using the magnetic repulsion force between the stators without interfering with the completely suspended state of the mover. The maximum load weight of the application reaches 100 kg, and the initial vibration isolation frequency is as low as 0.7 Hz. The application has the advantages of large bearing capacity, no Joule heat interference, adjustable load, and excellent three-direction ultra-low-frequency vibration isolation performance.

We provide speaker magnetic materials, magnetic circuits, and magnetized ring magnets that meet the essential requirements for wearable devices: small size and light weight; wide range of motion essential for ultra-low frequency reproduction; high linearity across the entire range of motion essential for sound field control; and low cost essential for consumer products. [Solution] In the speaker's magnetic circuit, the magnetic flux near the end face of the ring magnet is used, and ring magnets 201 and 202 that can only be magnetized in two directions are used. Depending on the application, one bidirectional magnetized ring magnet is used, or two types of bidirectional magnetized ring magnets are used as a pair on the outside and inside, or two or more bidirectional magnetized ring magnets of one type are used with spacers in between to form multiple layers, or two or more pairs of bidirectional magnetized ring magnets (one pair on the outside and one inside) are used with spacers in between to form multiple layers. A combination of bidirectional magnetized ring magnets that satisfies the required dimensions, mass, bass reproduction range, linearity, and cost is selected.