The Study of the Nonstationary Signal in Fault Diagnosis

In this paper, the space time-index plots were introduced and used to determine the nonstationarity of the fault diagnosis in order to handle faults in the nonstationary stage. By using the decomposition and reconstruction of wavelet transform for nonstationary signal, the author targeted on the bandwidth and select information with pertinence, and then analysed the reconstruct signal spectrum for extracting the typical character of fault. The results show that the space time-index method is applicable to judge the nonstationary and the wavelet transform method in fault diagnosis is effective for the nonstationary signal.

NONSTATIONARY STAGE OF QUASI‐CHERENKOV BEAM INSTABILITY IN PERIODICAL STRUCTURES

Analysis of nonstationary stage of quasi‐Cherenkov instability of electron beam in the case of two‐wave distributed feedback is carried out. Mathematical models and numerical methods of nonstationary quasi‐Cherenkov electron beam instability are proposed. Results of numerical experiments are proposed. Bifurcations of nonstationary solution are discussed. Straipsnyje analizuojama nestacionariosios fazes kvazi‐Cherenkovo elektronu spinduliuotes nestabilumas esant dvieju bangu saveikai su grižtamo ryšio pernešimu. Pasiūlyti šios elektronu spinduliuotes nestacionariosios fazes atveju matematiniai ir skaitiniai sprendimo metodai. Pateikti skaitinio eksperimento rezultatai. Aptartos nestacionariojo sprendinio bifurkacijos.