STUDY ON COAL FRACTOGRAPHY UNDER DYNAMIC IMPACT LOADING BASED ON MULTIFRACTAL METHOD

Coal fractography is a powerful tool for interpreting coal fracture behaviors, which is significant for dealing with failure issues encountered in deep coal mining. However, the accuracy of coal fractography highly depends on the method of quantitatively characterizing coal fracture surfaces. In this study, coal fractography under dynamic impact loading was investigated based on a multifractal method, the multifractal spectrum parameters were proposed to quantitatively describe the coal fracture surfaces. The width of the multifractal spectrum [Formula: see text] characterizes the uniformity of the surface asperity distribution, and the spectrum parameter [Formula: see text]–[Formula: see text] characterizes the proportion of dominant asperities on fracture surface. The coal fractography results indicate that larger loading rate leads to more asperities on the coal fracture surfaces, i.e. rougher fracture surfaces, and the fracture surfaces are dominated by small asperities induced by dynamic impact loading. In addition, significant anisotropy effect was found on the fracture surfaces under dynamic impact loading by the spatial distributions of multifractal spectrum parameter [Formula: see text]. The parameter [Formula: see text] was further utilized to determine the macrocrack direction and microfracture markings on the coal fracture surfaces, the results transpire that the multifractal method is feasible for coal fractographic analysis under dynamic loading conditions.

The Effect of Different Remazol Dye Concentrations and Soaking Times in Dye-Sensitized Solar Cell

Water based Remazol Brilliant Red, Orange and Violet dyes were used as the dye sensitizer in dye-sensitized solar cell. The performance of the solar cell was investigated between the dye concentrations, 0.25 mM and 2.5 mM and three different soaking times which at 3 hours, 12 hours and 24 hours. The adsorption peaks of the dyes were observed using ultraviolet-visible-near infrared (UV-Vis-NIR) Spectrometer and the performance of the dye-sensitized solar cell was measured using Spectrum Parameter Analyzer (SPA). The results show that the device efficiency was increased with dye concentration, but, the DSSC performance at different soaking times performed differently with the previous study. The highest conversion efficiency of 1.125 % was obtained for Remazol Brilliant Red at concentration of 2.5 mM at 3 hours soaking time.