Chaotic behaviour of acoustic emission induced in hard coal by gas sorption-desorption

Binary gas sorption/desorption experiments on a bituminous coal: Simultaneous measurements on sorption kinetics, volumetric strain and acoustic emission

“…The AE linked to gas sorption-desorption processes in hard coal has not yet been fully examined. Results of investigations of frequency spectra of AE signals induced in coal by gas sorption or water flow showed, that the microfracturing is a reasonable source of acoustic emission (Majewska et al, 1996(Majewska et al, , 1997.…”

Changes of acoustic emission and strain in hard coal during gas sorption–desorption cycles

“…In spite of extensive work comprising empirical and theoretical studies of sorption processes as well as coal structure analysis (Hall et al, 1992;Ceglarska-Stefańska and Czapliński, 1993;Gamson et al, 1993;Milewska-Duda and Duda, 1993;Ceglarska-Stefańska, 1994;Amarasekera et al, 1995), the understanding of coal-gas system is still insufficient. Recent research indicates that acoustic emission techniques (AE) are promising for such investigations (Majewska et al, 1994(Majewska et al, , 1996(Majewska et al, , 1997Majewska and Ziętek, 1999;Majewska and Mortimer, 2006).…”

Linear and nonlinear attributes of ultrasonic time series recorded from experimentally loaded rock samples and total failure prediction

“…To get some ideas regarding the limits of FDs derived by means of this method we quote several FD of known processes estimated by using relationship (8): uniform white noise D w ¼ 1.85, Gaussian white noise D w ¼ 1.78, noise D w ¼ 1.44, Brownian process D w ¼ 1.42, self-similar process D w ¼ 1.26 and simple linear trend D w ¼ 1.02.…”

“…Rudajev et al [7] has observed that linear autocorrelation coefficients calculated from the time series of UE rate increase in time towards the total failure. The fractal analysis has been applied to the post-failure stage of loaded samples by Majewska and Mortimer [8]. It was shown in their study that fractal dimensions (FDs) increase after the total failure of loaded rock samples.…”