For evolutionary random excitations, a general method of analyzing nonstationary random responses of systems was presented in this paper. Firstly, for the evolutionary random excitation model, the evolutionary power s...For evolutionary random excitations, a general method of analyzing nonstationary random responses of systems was presented in this paper. Firstly, for the evolutionary random excitation model, the evolutionary power spectrum density function （EPSD） of a random excitation was given by wavelet transform. Based on the EPSD, the nonstationary responses of a SDOF system subjected to evolutionary random excitations were studied. The application and validity of presented method were illustrated by numerical examples. In numerical examples, the recently developed stochastic models for El Centro （1934） and Mexico City （1985） earthquakes which preserve the nonstationary evolutions of amplitude and frequency content of ground accelerations were used as excitations. The nonstationary random mean-square responses of a SDOF system under these two excitations were evaluated and compared with simulated results.展开更多
A simple theoretical model based on plasma physics is presented to analyze the microwave plasma effects on the electronic circuits.Results show that under certain parameter conditions the threshold for damaging the el...A simple theoretical model based on plasma physics is presented to analyze the microwave plasma effects on the electronic circuits.Results show that under certain parameter conditions the threshold for damaging the electronic circuits decreases with the decrease of the frequency of the high-power microwave.In addition,the oscillation amplitudes of the plasma electrons increase dramatically when the plasma frequency is near the high-power microwave frequency, which can easily damage the electronic circuits.展开更多
文摘For evolutionary random excitations, a general method of analyzing nonstationary random responses of systems was presented in this paper. Firstly, for the evolutionary random excitation model, the evolutionary power spectrum density function （EPSD） of a random excitation was given by wavelet transform. Based on the EPSD, the nonstationary responses of a SDOF system subjected to evolutionary random excitations were studied. The application and validity of presented method were illustrated by numerical examples. In numerical examples, the recently developed stochastic models for El Centro （1934） and Mexico City （1985） earthquakes which preserve the nonstationary evolutions of amplitude and frequency content of ground accelerations were used as excitations. The nonstationary random mean-square responses of a SDOF system under these two excitations were evaluated and compared with simulated results.
文摘A simple theoretical model based on plasma physics is presented to analyze the microwave plasma effects on the electronic circuits.Results show that under certain parameter conditions the threshold for damaging the electronic circuits decreases with the decrease of the frequency of the high-power microwave.In addition,the oscillation amplitudes of the plasma electrons increase dramatically when the plasma frequency is near the high-power microwave frequency, which can easily damage the electronic circuits.
