51 results about "Harmonic balance" patented technology

The invention relates to a recognizing and locating method for abnormal sound in public places, which belongs to the technical field of audio signal processing. The method uses a double-threshold algorithm and a Welch method to estimate a power spectrum to judge whether the abnormal sound exists in the public places. Feature sequence signals of the abnormal sound are converted into a spectrogram of a time-frequency domain, and problems of feature extraction and classification recognizing of the abnormal sound are solved by using the sparse coding sound recognition technology sensed by hearing. In order to restrain effects of pulse noise in background noise on the abnormal sound locating, non-linear transformation is introduced, and cross-correlation function peak capacity of the abnormal sound is improved. A traditional harmonic balance (HB) weight function is modified, and weight changes caused by low signal-to-noise ration are lowered. Multi-frame data weight processing is introduced, a novel HB weight generalized cross correlation algorithm is suitable for capacity for processing abnormal sound locating in complex acoustic environments in the public places. Due to the fact thatthe method is combined with the sparse coding sound recognition technology based on hearing sense and the modified sound locating technology of time difference of arrival, sound information accompanied with abnormal events can be utilized better, and intelligent level of a monitoring system in the public places can be improved.

The present invention provides a time-domain broadband harmonic domain beamformer and a beamforming method for a circular array. The beamformer includes: a harmonic transformation module and a beam pattern synthesis module. The data received by the array element is sampled and passed through the harmonic transformation module, and then the ring harmonic domain data of each order output by the harmonic transformation module are summed through the corresponding FIR filter to obtain the beam output. Using this beamforming method, the obtained time-domain broadband harmonic domain beam can take into account multiple performance indicators of the beamformer, and can appropriately reduce the number of performance indicators that need to be considered, that is, properly select the cost function and constraint function according to actual needs, Different constraint combinations constitute different beam optimization criteria, so it has strong practicability and wide application adaptability; and the number of channels M in the classical array element domain beamforming is reduced to N+ in the harmonic domain processing of the present invention 1 (where M>2N), reducing the amount of calculation.

The invention discloses a vibration analysis method for dry frictional damping mistuned blades with tendons and shroud bands. The method comprises the steps of for actual mistuned states of the blades of a steam turbine, performing three-dimensional contact finite element analysis firstly to obtain support reactions of nodes of contact surfaces of the tendons and the shroud bands of the entire circle of the blades; secondly establishing a contact surface relationship by adopting spring damping units, considering positive pressures, areas and frictional coefficients at the spring damping units, and building a dry frictional damping mistuned vibration analysis model based on a Mindlin micro-sliding friction model and a harmonic balance method; thirdly considering a pre-stress and adopting harmonic response analysis for obtaining convergency values of vibration responses of the blades through iterative solving; and through cyclic calculation, obtaining vibration amplitude response curves of the dry frictional mistuned blades, and performing further extraction to obtain an inherent frequency and a vibration mode. The method is of important significance for dry frictional damping mistuned analysis of the blades and improvement of mistuned bladed disk vibration.