4 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.

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.

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.