The Study On Dynamic Characteristics Of Electric Sandpile Resistance And Its Evolution

Granular matter is an important branch of the discipline of soft material. Inrecent decades, granular matter exhibits many unique properties and has attractedmuch attention. So far, some research results have been obtained with respect togranular matter. In particular, the self-organized criticality has been proposed,which can explain some unique properties of granular matter. However, thistheory is based on the BTW model, which is different from the real granularmatter to some extent. There is a controversy on the self-organized criticality.Therefore, the purpose of this thesis is to develop a new model based on theelectricity, which can provide more details in comparison with the conventionalsand model. Furthermore, the evolution of self-organization process in granularmatter system has been studied through the resistance of metallic beads subjectedto a disturbance.In this thesis, the researches on self-organized criticality have beensummarized firstly. In addition, we reviewed the general methods applied forstuding the self-organized criticality. Furthermore, the related experiments havebeen carried out. It is found that after single perturbation, the resistance of themetallic beads with different scales shows the different probability of obeyingsome rules, which is related to the size and dimension of the metallic particulateand the metallic beads forming.The metallic beads with different scales have been perturbed by many times.It is found that the resistance of metallic beads with the specific size exhibitssome regularities. The variation of resistance showing no regularity even afterthe initial perturbation would gradually change with regularity. The time series ofseveral perturbations has been concerned. The R/S analysis indicates that whenthe resistance varied unregularly, this time series exhibits significant correlation.This phenomenon is due to the predominant effect of the external drive on the resistance. With the perturbation persisting, the previous time series has beenanalyzied again. The results show that there is a correlation between the previousand later resistance, implying that the system exhibits long period memory effect.Moreover, the change between previous and later resistance has also beeninvestigated. It is found that there is a power law between the magnitude andprobability of the resistance variation, indicating the self-organized criticality ofthe studied system. In addition, the different single perturbation parts have beenselected with respect to the time series. The time series analysis of the resistancevariation has been performed by using the method of phase space reconstruction.The results demonstrate that the variation of resistance after the perturbationexhibits fractal characteristics. Moreover, with increasing the dimensions of thephase space, the correlation dimension remains unchanged. Therefore, it isreasonalbe to extent the metallic beads to the higher dimensions space,promoting the further studies.