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1

Numerical analysis of slow and fast light effect in semiconductor optical amplifier with certain facet reflection

Qin Cui, Jiang Yu, Zhen Li

Optica Applicata

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2022

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Vol. 52, nr 4

655--667

EN

In this paper, the slow and fast light (SFL) effects of the semiconductor optical amplifier (SOA) having certain facet reflections are theoretically investigated. The theoretical model is used to account for the SFL phenomenon causing the coherent population oscillation. The influence of the current modulation frequency, the value of the current, the linewidth enhancement factor, facet reflectivity as well as the relative phase of the modulated current on the phase delay in the SOA are studied. It is demonstrated that the SFL effect could be controlled by the modulation frequency, the value and relative phase of the current. Finally, it is shown that the magnitude of the SFL delay could be tuned by a change in the linewidth enhancement factor as well as the facet reflectivity of the SOA.

2

Brittleness evaluation method of shale based on confining pressure correction

Liu Lifeng, Guan Meng, Zhao Haitao, Wang Haipeng, Gao Tianyu, Jiang Yu

Acta Geophysica

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2022

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Vol. 70, no 1

211--223

EN

The influence of confining pressure on the brittleness of shale is very significant, usually with the increase in confining pressure; the shale shows a tendency to change from brittle to plastic. Therefore, the confining pressure correction is an important part of the brittleness evaluation, but it is often neglected in the conventional shale brittleness evaluation methods. This paper proposes a two-step confining pressure correction method to integrate the brittleness evaluation methods of mineral components, elastic parameters, and mechanical parameters and to comprehensively construct a shale brittleness evaluation index based on confining pressure correction. Step 1 zero confining pressure correction: the elastic brittleness index at zero confining pressure is calibrated using the mineral brittleness index to remove the effect of envelope pressure on brittleness and thus represent the intrinsic brittleness characteristics of the rock. Step 2 confining pressure trend correction: the mechanical parameters are used to correct the rock for the trend of confining pressure in order to reasonably characterize the weakening effect of the confining pressure on the brittleness of the rock, and reasonably characterize the transition from brittle to plastic as the confining pressure increases. By applying it to the brittleness evaluation of actual logging data, the evaluation results can truly and objectively characterize the brittleness of rock under in situ confining pressure.

3

Design and test study of a new mixed control method for magnetorheological semi-active suspension based on electromechanical analogy theory

Jiang Yu, Wang Ruochen, Ding Renkai, Sun Dong, Liu Wei

Journal of Theoretical and Applied Mechanics

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2021

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Vol. 59 nr 2

189--201

EN

For pursuing high performance, the development of semi-active suspension control tends to be complicated and ignores practicability. A new mixed control method effectively suppressing vibration of the vehicle body in the whole frequency band is proposed based on electromechanical analogy theory. Simulation results show that in comparison with passive suspension, on a long slope bumpy road, the mixed control reduces body acceleration by 21.49% and the maximum amplitude by 22.40%. On a C class road, the mixed control reduces body acceleration by 9.78%. Finally, an ECU hardware-in-the-loop test is conducted, which verifies the effectiveness and feasibility of the new mixed control method.