10 results about "Natural resonance" patented technology

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.

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 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 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.

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.