Papers by Keyword: Triggering

Abstract: Have designed the software and hardware formation of the six-pulse triggering device which is based on the all-controlled bridge type of Three-phase circuit of the single-chip microcomputer PIC16F877A . This new controllable silicon triggering system can show the triggering angle specifically and work steadily.

Abstract: Self-excited combustion oscillations are caused by a coupling between acoustic waves and unsteady heat release. A premixed laminar flame in a Rijke tube, anchored to a metal gauze, is considered in this work. The flame response to flow disturbances is investigated by developing a nonlinear kinematic model based on the classical-equation, with the assumption of a time-invariant laminar flame speed. Unsteady heat release from the flame is assumed to be caused by its surface variations, which results from the fluctuations of the oncoming flow velocity. The flame is acoustically compact, and its presence causes the mean temperature undergoing a jump, whose effect on the dynamics of the thermo-acoustic system is discussed. Coupling the flame model with a Galerkin series expansion of the acoustic waves present enables the time evolution of the flow disturbances to be calculated. It was found that the model can predict the mode shape and the frequencies of the excited combustion oscillations very well. Moreover, the fundamental mode is found to be the easiest one to be triggered among all acoustic modes. To gain insight about the mode selection and triggering, further numerical investigation is conducted by linearizing the flame model and recasting into the popular formulation.

Abstract: The work is devoted to the problem of role of ambient factors (external electromagnetic field, in particular) in the process of ageing of mechanically burden nonmetallic solids (rocks). A specific research point is the effect of temporary activation of Acoustic Emission (AE) of rocks specimens during action of EM field pulses applied externally. Extended experimental studies of responses of AE have been conducted to evince the changes in defects accumulation process in loaded specimens due to external power impacts (EPI). The experiments have been held on noiseless rheological machines available at Bishkek Geodynamic Research Center - RS RAS. We have tested a number of specimens made of different materials and analyzed the temporal dependence of AE activity during exposure in electric field and crossed electric and magnetic fields; the compressive load being constant. The effect of AE stimulation by power pulses (triggering) has been verified. The obtained results allow to distinguish two kinds of AE activation. The first kind involves simultaneous well correlated growth of numbers of minor and major AEs (so-called selfconsistency of temporal plots of activity of different range acoustic events). The second kind represents dissimilar variations: the increment of activity of minor energy AEs, but the decrement of those of major energy. The first kind of solids material responses to EPI is prevailing when the compressive loads is under 0,85 of fracturing value. The episodes of dissimilar AE responses may signify that electromagnetic control of defects accumulation process inside rocks is possible, in principle.