提出了一种由直流后备式熔断器和直流真空负荷开关串联组成的直流组合电器,对其直流开断特性进行了仿真和实验研究。新型直流组合电器可完成直流电流的全范围开断:当开断额定电流和过载电流时,采用真空直流负荷开关利用人工电流过零法开断电流,此时后备式熔断器不动作;当开断大过载电流和短路电流时,采用后备式直流熔断器直接开断大电流,也可以将大电流限制至较低幅值再采用真空直流负荷开关进行分断。实验结果证明,该直流真空负荷开关可以在5 ms内成功开断200 A至1.7 k A的直流电流,直流后备式熔断器可以开断1.7 k A及以上的直流电流。
As commercial memristors are still unavailable in the market, mathematic models and emulators which can imitate the features of the memristor are meaningful for further research. In this paper, based on the analyses of characteristics of the q–? curve, an exponential flux-controlled model, which has the quality that its memductance(memristance) will keep monotonically increasing or decreasing unless the voltage's polarity reverses(if not approach the boundaries), is constructed. A new approach to designing the floating emulator of the memristor is also proposed. This floating structure can flexibly meet various demands for the current through the memristor(especially the demand for a larger current). The simulations and experiments are presented to confirm the effectiveness of this model and its floating emulator.
An argon atmospheric pressure plasma jet was employed to treat L929 murine fibroblasts cultured in vitro.Experimental results showed that,compared with the control cells,the treatment of fibroblasts with 15 s of plasma led to a significant increase of cell viability and collagen synthesis,while the treatment of 25 s plasma resulted in a remarkable decrease.Exploration of related mechanisms suggested that cold plasma could up-regulate Cyclin D1 gene expression and down-regulate p27 gene expression at a low dose,while it could down-regulate Cyclin D1 expression and up-regulate p27 expression at a higher dose,thus altering the cell cycle progression,and then affecting cell viability and collagen synthesis of fibroblasts.
In vacuum switch devices,the connection bus bar out of the vacuum interrupter will generate a transverse magnetic field in the arc column region,and under the influence of this magnetic field,the whole arc column will deflect from the electrode center,thus leading to deflected anode erosion.In this paper,a two-dimensional deflected anode erosion model is established,anode erosions under different deflection distance are simulated and analyzed,and results of anode surface temperature,anode melting and surface evaporation flux are obtained.The simulation results show that the deflected heat flux density will lead to deflected distribution of anode temperature,saturated vapor pressure and vapor flux correspondingly,and the morphology of the anode melting pool has also the same deflection.Moreover,the anode center temperature and its gradient along the y direction decrease with the increase of deflection distance.On the contrary,the temperature of the anode side surface,toward which the heat flux density deflects,increases with increasing deflection distance.Related experiments also verify the correctness of the model and simulation results.
Non-thermal equilibrium atmospheric pressure plasma jet(APPJ)is a cold plasma source that promises various innovative applications,and the uniform APPJ is more favored.Glow discharge is one of the most effective methods to obtain the uniform discharge.Compared with the glow dielectric barrier discharge(DBD)in atmospheric pressure,pure helium APPJ shows partial characteristics of both the glow discharge and the streamer.In this paper,considering the influence of the Penning effect,the electrical and optical properties of He APPJ and Ar/NH3APPJ were researched.A word"Glow-like APPJ"is used to characterize the uniformity of APPJ,and it was obtained that the basic characteristics of the glow-like APPJ are driven by the k Hz AC high voltage.The results can provide a support for generating uniform APPJ,and lay a foundation for its applications.
