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Porous graphitic carbon nitride nanosheets were synthesized by the thermal condensation method using various precursors such as urea and melamine. Relevant properties of as-synthesized products were investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), thermogravimetric analysis (TG) and differential thermal analysis (DTA). The overall results suggest that the formation of porous graphitic carbon nitride nanosheets with a varied morphology can be achieved using diverse precursors through this process. Based on this product yield analysis, it is suggested that melamine and the lower synthesis temperature be selected to achieve the higher yield of graphitic carbon nitride production. The present work provides a facile and economic method for controlling the morphology and properties of graphitic carbon nitride products.

The compressive mechanical properties of a Ti–29Nb–13Ta–4.6Zr alloy were investigated at room temperature under various strain rates. The parameters of a modified Johnson–Cook constitutive equation were determined to describe the strain softening behavior under dynamic conditions. The testing results under compression show yield strength evidently increases with the increase of the strain rate. Moreover, it was found that the strain-rate effect of the yield strength upon dynamic deformation is more significant than that upon quasi-static deformation. In order to characterize the impact-initiated reaction behavior of Ti–29Nb–13Ta–4.6Zr alloy, the quasi-sealed test chamber was used to measure the pressure caused by energy released of fragments. It was obviously shown that the exothermic chemical reaction was more intense with the increase of impact velocity.

Superhydrophobic surfaces have attracted great attention for their distinguishing properties. The key factor for a surface to achieve superhydrophobic is the intrinsic hierarchical structure. Traditional graphene based materials are not suitable for the construction of hierarchical structures because these planar materials will adhere to the substrates during preparation. In this paper, based on the exhaustive experimental results and systematically analysis of the interaction mechanism between p-phenylenediamine and graphene oxide, it is proved that p-phenylenediamine modified graphene oxide has better strength, and it can be used to prepare super-hydrophobic surfaces with micro-nano hierarchical structures. The approach described here could be applied to the construction of superhydrophobic graphene related coating without other rigid supporting materials. Keywords: Graphene oxide, p-Phenylenediamine, Superhydrophobic, Hierarchical structure, Coating

In order to realize the online noncontact detection of the Abrasion of the Pantograph Slipper of Urban Rail Train, the abrasion detection technology of pantograph slipper of urban rail train is studied. In this paper, an abrasion detection method of pantograph slipper of urban rail train based on image processing is proposed, and the steps are as follows: First, the mixed noise of the original image from the acquisition system is filtered by image filtering. Then, the edge of Pantograph Slipper in the image is detected by the adaptive Canny edge detection based on histogram concavity analysis after image filter. Finally, the abrasion curve of the Pantograph Slipper is obtained by camera calibration and curve blending, and which is used to judge whether the abrasion of the pantograph slipper is transfinite. The results of the experiment showed that the proposed method is effective to detect the pantograph slipper abrasion curve in the original image. The proposed method is effective to realize the online non-contact detection of the Abrasion of the Pantograph Slipper of Urban Rail Train.