17 results about "Natural resonance" patented technology

The invention discloses a distributed photovoltaic access power distribution network relay protection analysis method and system, and belongs to the technical field of photovoltaic grid connection, and the method specifically comprises the steps: injecting a dynamic resonance detection signal at the AC side of a current converter of a photovoltaic grid-connected system, and enabling the frequency to be matched with the natural resonance frequency of a target section; analyzing the energy focusing effect of the dynamic resonance detection signal in the power distribution network, and generating a resonance energy distribution map; when the energy density of a certain section in the resonance energy distribution map exceeds a preset threshold value, the photovoltaic output current waveform is adjusted to be a discontinuous waveform containing periodic intermittent cutoff; based on the reflection delay difference of the waveform in the fault section, constructing a space-time mapping model of a fault point, and analyzing and determining a fault position; according to an output result of the space-time mapping model, controlling a photovoltaic side circuit breaker and a power grid side relay to execute a selective tripping action based on waveform phase synchronization; according to the invention, the sensitivity and reliability of distributed photovoltaic access power distribution network relay protection are improved.

The invention discloses a wind turbine generator blade damage judgment method and detection system based on voiceprint detection, and belongs to the technical field of wind turbine generator blade detection. The damage judgment method comprises the following steps: acquiring environmental parameters of a wind power plant, and establishing a sound velocity correction model based on the environmental parameters; acquiring a blade resonance sound signal, and correcting the blade resonance sound signal based on the sound velocity correction model to obtain a blade resonance sound signal with a high signal-to-noise ratio; performing FFT spectrum analysis on the blade resonance sound signal with the high signal-to-noise ratio, identifying the peak position of the first three-order natural resonance frequency of the blade, and performing analysis to obtain the current modal frequency, damping ratio and sub-band energy distribution entropy value of the blade; historical baselines of the modal frequency, the damping ratio and the sub-band energy distribution entropy of the blade in the healthy state are obtained, and the modal frequency offset, the damping ratio change rate and the acoustic impedance spectrum entropy of the blade are obtained; and wind turbine generator blade damage determination is carried out by using a high-precision time difference detection technology.

A method and apparatus for evaluating light-weight cement (LWC) bond conditions in production well in presence or absence of the tubing. The apparatus includes a tool string that can be lowered into the casing or the tubing. The tool string includes a segmented transducer ring matrix to excite the surrounding medium resulting in vibrations. The tool string further includes an impedance measurement circuit that can determine natural resonance frequencies of the structural components. The impedance measurement circuit can determine certain non-harmonic resonance mode shapes for mechanical impedance measurements that are sensitive to the LWC bond conditions. A machine learning model can be used for segmented impedance measurements to correct effects from the tubing eccentricity inside the casing. Lab calibration generates bond index mapping table and the field logging impedance measurement data can be processed into the bond indexes to further evaluate LWC bond conditions.

A low-loss hexagonal ferrite material in S and C bands and its preparation method, belonging to the technical field of ferrite material preparation. The hexagonal ferrite material includes a main phase and an additive. The main phase is Ba5Cu 2‑x Ni x Ti3Fe 12 O 31 , where x = 0.5 to 1, and the additive is SiO2; the additive accounts for 0.5 to 1.5 wt% of the mass of the main phase; by changing the ratios of Cu 2+ , Ni 2+ , the magnetocrystalline anisotropy, magnetic permeability and natural resonance frequency are regulated, and the real part of the magnetic permeability μ' ≥ 1.8, the magnetic loss tangent tanδ m ≤ 0.08, the real part of the dielectric constant ε' ≥ 10, and the dielectric loss tangent tanδ d ≤ 0.01 are achieved in the S and C bands. It can be used for the miniaturization of Sub-6GHz antennas, improving the antenna bandwidth and reducing the impedance mismatch.

An additional element for focusing a time-varying magnetic flux (B1), for installation in a sample receptacle of an NMR probe head includes one or more cover elements that are each electrically conductive along a respective outer surface. The cover elements form one or more closed conductor loops, each enclosing a conductor loop area, that collectively form the cover zone, which has an area Acover. The cover zone at least partially encloses a passage window having an area Awindow with Acover≥2*Awindow. The additional element includes at least one capacitively acting structure, so that the additional element forms an electrical resonant circuit comprising the one or more cover elements, with a natural resonance of a resonance frequency RF, where 5 MHz≤RF≤3000 MHz. The additional element can be used to improve the signal-to-noise ratio with low-volume test samples when measuring in an existing NMR probe head.

A device and method of measuring internal pressures without direct contact with the internal liquid by using external sound wave (vibration) emitters to generate a range of low frequency vibrations or sound waves to induce the natural resonance points at multiple frequencies within a body part or fluid container where the internal pressure measurement is desired, focusing on muscle fascial compartment pressure measurement. A separate microphone receiver or receivers detect the different resonant frequencies of the container or body part while it is being vibrated by the emitters, and estimates the pressure inside the container without direct sampling through mathematical computations and comparison of the resonant values to values obtained previously from laboratory control tests with known pressure values or healthy contralateral limbs.

The invention provides a preparation method of an MMIC chip, the chip, electronic equipment and a preparation device, and relates to the technical field of semiconductors. The method comprises the following steps: preparing an MMIC functional circuit on the front surface of a wafer; according to the target thickness of the wafer, carrying out thinning operation on the back surface of the wafer; preparing a resonance suppression circuit on the back surface of the thinned wafer; scribing the wafer on which the MMIC functional circuit and the resonance suppression circuit are prepared to obtain an MMIC chip; wherein the resonance suppression frequency band of the resonance suppression circuit is matched with the natural resonance frequency band of a packaging cavity, and the packaging cavity is used for packaging the MMIC chip. Resonance generated by the packaging cavity can be effectively suppressed through the resonance suppression circuit, no extra resonance suppression material needs to be placed, on the basis of ensuring the electrical performance of the MMIC chip, the cavity resonance suppression capability and the environmental adaptability are improved, the lightweight requirement can be met, the process is simple, and the integration level is high.

An additional element for focusing a time-varying magnetic flux (B1), for installation in a sample receptacle of an NMR probe head includes one or more cover elements that are each electrically conductive along a respective outer surface. The cover elements form one or more closed conductor loops, each enclosing a conductor loop area, that collectively form the cover zone, which has an area Acover. The cover zone at least partially encloses a passage window having an area Awindow with Acover≥2*Awindow. The additional element includes at least one capacitively acting structure, so that the additional element forms an electrical resonant circuit comprising the one or more cover elements, with a natural resonance of a resonance frequency RF, where 5 MHz≤RF≤3000 MHz. The additional element can be used to improve the signal-to-noise ratio with low-volume test samples when measuring in an existing NMR probe head.

The present invention provides a detection circuit and a detection method for a MEMS resonator. The detection circuit includes: a MEMS resonator; a charge amplifier, whose output terminal outputs a resonance induction signal; a rectifier, configured to flip or cut off the negative value part in the resonance induction signal to obtain a rectified resonance induction signal; an integrator, configured to integrate the rectified resonance induction signal with a set integration time as a period; a sampling circuit, sampling the output of the integrator to obtain an integration sampling value; a comparator, obtaining a digital square wave signal; a counter, which is triggered by a predetermined transition edge of the digital square wave signal for counting, and the count value per unit time is denoted as N1; a processing unit, which calculates the natural resonance frequency F0 based on the count value N1 and the unit time, and calculates the quality factor Q based on the natural resonance frequency F0 and the integration sampling value. In this way, the resonance frequency and quality factor of the MEMS resonator can be measured quickly and accurately.

The present invention discloses a low-loss oriented BaM hexagonal ferrite material covering the sub-6 GHz band and a preparation method thereof, based on Co with uniaxial anisotropy 2+ and Ru 4+ ion-combined substituted BaM hexagonal ferrite material, using goethite powder with a high aspect ratio synthesized by the hydrothermal method as a raw material to replace the iron red (Fe2O3) required in the traditional ferrite preparation process, enabling the Co 2+ / Ru 4+ ion-combined substituted BaM hexagonal ferrite to achieve oriented preferred growth, thereby greatly increasing the magnetic resonance frequency and meeting the requirements of the low-loss sub-6 GHz miniaturized antenna for a high operating frequency. Secondly, by adding low-melting-point Bi2O3, the particle size and magnetic domain width are increased, which can reduce the domain wall resonance relaxation frequency, resulting in an obvious separation between the natural resonance point and the domain wall resonance point, ensuring the low magnetic loss characteristics of this material.

The invention provides a ferrite composite wave-absorbing material and a preparation method thereof, and belongs to the technical field of wave-absorbing materials. In an inert atmosphere, microcrystalline graphite, manganese carbonate, zinc oxide and iron oxide are mixed, and the obtained mixed powder is subjected to high-temperature ball milling to prepare the ferrite composite wave-absorbing material. The ferrite composite wave-absorbing material has enhanced dielectric loss and enhanced magnetic loss, and the dielectric loss comes from dipole polarization, interface polarization and conduction loss provided by a carbonaceous material. The magnetic loss comes from eddy-current loss provided by ferrite particles and a special three-dimensional porous layered structure of natural resonance microcrystalline graphite, so that incident electromagnetic waves are subjected to multiple reflection and scattering in the material, the transmission path of the electromagnetic waves is prolonged, the transmission time is prolonged, and the dielectric loss and the magnetic loss are amplified.

The present invention belongs to the technical field of soft magnetic film materials, and relates to a planar anisotropic rare earth-based high-frequency soft magnetic film and a preparation method thereof. The rare earth-based high-frequency soft magnetic film is composed of RE2TM 17 , wherein RE is a rare earth element and TM is a transition metal element; the preparation method comprises the following steps: depositing a rare earth-transition metal film on a substrate, and then preparing RE2TM by vacuum annealing. 17 Soft magnetic film. This invention breaks through the Acher limit of soft magnetic film and the composition obtained is RE2TM 17 The planar anisotropic rare earth-based high-frequency soft magnetic film improves the natural resonance frequency without sacrificing magnetic permeability.

Wave-absorbing materials in the form of a nickel-carbon composite that includes a plurality of modified carbon particles, where each of the modified carbon particles includes a nickel nanoparticle core and a carbon layer wrapped on a surface of the nickel nanoparticle core; and a plurality of the modified carbon particles form an octahedral structure. When a high-frequency microwave interacts with the nickel-carbon composite, the composite has a stronger magnetic loss performance due to various magnetic loss characteristics such as natural resonance and eddy current loss of the magnetic nickel nanoparticles. In addition, the carbon layer, as a shell layer, can provide a directional electron migration path in a special octahedral space structure to construct a conductive network.

Measuring system, in particular compact measuring device and / or Coriolis mass flow meter, for flowing media, in particular in pipelines, which measuring system comprises: - a vibration-type measuring transducer (MW) through which a medium, in particular a gas and / or a liquid, a paste or a powder or another flowable material, flows during operation to generate primary signals corresponding to parameters of the flowing medium, in particular a mass flow rate, a density and / or a viscosity, as well as converter electronics (ME) electrically coupled to the measuring transducer to control the measuring transducer and to evaluate primary signals supplied by the measuring transducer, - where the transducer -- at least one measuring tube (10; 10') for guiding flowing medium, -- at least one electromechanical, in particular electrodynamic, vibration exciter for exciting and / or maintaining vibrations of the at least one measuring tube, in particular bending vibrations of the at least one measuring tube about an imaginary vibration axis imaginarily connecting an inlet-side first measuring tube end of the measuring tube and an outlet-side second measuring tube end of the measuring tube with a natural resonance frequency of the measuring transducer, -- a first vibration sensor (51), in particular an electrodynamic one, for detecting vibrations, in particular on the inlet side, of at least the at least one measuring tube and for generating a first primary signal (s) representing vibrations, in particular on the inlet side, of at least the at least one measuring tube 1 ) of the transducer, and -- a second vibration sensor (52), in particular an electrodynamic one, for detecting vibrations, in particular on the outlet side, of at least the at least one measuring tube and for generating a second primary signal (s) representing vibrations, in particular on the outlet side, of at least the at least one measuring tube 2 ) of the transducer; and - where the converter electronics -- at least one driver signal causing vibrations, in particular bending vibrations, of the at least one measuring tube (i exc ) for the vibration exciter, and -- by means of the first primary signal and by means of the second primary signal and using a Reynolds number measurement value generated during operation by means of the driver signal and representing a Reynolds number, Re, for the medium flowing in the transducer, a pressure difference measurement value (X Δp) is generated which represents a pressure difference occurring between two predetermined reference points in the flowing medium, in particular those located within the measuring transducer, in particular such that a first of the two reference points is located on the inlet side and a second of the two reference points is located on the outlet side in the measuring transducer.

The invention discloses a low-loss oriented BaM hexagonal ferrite material covering a sub-6 GHz frequency band and a preparation method thereof, based on a BaM hexagonal ferrite material jointly substituted by Co < 2 + > and Ru < 4 + > ions with uniaxial anisotropy, goethite powder which is synthesized by a hydrothermal method and has a high length-diameter ratio is used as a raw material, iron oxide red (Fe2O3) required in a traditional ferrite preparation process is replaced, and the low-loss oriented BaM hexagonal ferrite material covering the sub-6 GHz frequency band and the preparation method of the low-loss oriented BaM hexagonal ferrite material covering the sub-6 GHz frequency band are obtained. And the BaM hexagonal ferrite jointly replaced by Co < 2 + > / Ru < 4 + > ions realizes orientation preferred growth, so that the magnetic resonance frequency is greatly improved, and the requirement of a low-loss sub-6GHz miniaturized antenna on high working frequency is met. Secondly, by adding low-melting-point Bi2O3, the particle size and the magnetic domain width are increased, so that the domain wall resonance relaxation frequency can be reduced, natural resonance points and domain wall resonance points are obviously separated, and the low magnetic loss characteristic of the material is ensured.

The present invention discloses a distributed photovoltaic access distribution network relay protection analysis method and system, which belongs to the field of photovoltaic grid-connected technology, and specifically includes: injecting a dynamic resonance detection signal on the AC side of the converter of the photovoltaic grid-connected system, with the frequency matching the natural resonance frequency of the target section; analyzing the energy focusing effect of the dynamic resonance detection signal in the distribution network to generate a resonance energy distribution spectrum; when the energy density of a certain section in the resonance energy distribution spectrum exceeds a preset threshold, adjusting the photovoltaic output current waveform to a discontinuous waveform including periodic intermittent current interruption; constructing a space-time mapping model of the fault point based on the reflection delay difference of the waveform in the fault section, and analytically determining the fault location; according to the output result of the space-time mapping model, controlling the photovoltaic side circuit breaker and the grid side relay to perform a selective tripping action based on waveform phase synchronization; the present invention improves the sensitivity and reliability of the distributed photovoltaic access distribution network relay protection.

The invention belongs to the technical field of electroacoustic transducers, and relates to a vibrating diaphragm preparation method, a high pitch loudspeaker assembly and a horn type loudspeaker, the loudspeaker assembly comprises a voice coil driving assembly and a vibrating diaphragm assembly, the vibrating diaphragm assembly comprises a dangling edge, a vibrating diaphragm body with non-uniform thickness, a reinforcing ring and a damping material, the edge area of the vibrating diaphragm body is embedded and fixed in the reinforcing ring, and the damping material is embedded in the edge area of the vibrating diaphragm body. The reinforcing ring and the dangling edge are fixedly connected together, and the damping material tightly covers the top surface of the vibrating diaphragm body; the beneficial effects are that the diaphragm body employs a non-uniform thickness design scheme, local structure rigidity distribution is optimized, natural resonant frequency is improved, segmentation vibration is effectively inhibited, the reinforcing ring disperses working stress of the diaphragm body, and the damping material further inhibits resonance and segmentation vibration. The inherent defects of the vibrating diaphragm body in the high-pitch compression driver are jointly overcome, the acoustic performance and the structural reliability are considered, and the technical problems that an existing vibrating diaphragm has segmentation vibration, is high in brittleness and easy to damage and is poor in stability under a high sound pressure level are solved.