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Non-smooth surface of a nano or micro-scale fiber has an extremely large surface area and a tremendously high surface energy (geometric potential). This paper focuses on the formation mechanism of fabrication of a non-smooth surface by electrospinning through controlling solvent evaporation and nanoscale adhesion of nanoparticles on the surface. Poly(vinylidene fluoride), multi-wall carbon nanotubes and a binary solvent system are adopted in the experiment to elucidate how to fabricate nanoscale porous nanofibers and lotus-surface-like nanofibers. A nanoparticle?s vibration near its equilibrium is also discussed, which also affects greatly the surface morphology.

A fractal model for pressure drop through a cigarette filter is suggested, the fractal dimensions of both a single fiber and the filter?s cross-sections are calculated, which are two main factors affecting the pressure drop. The two-scale transform is made to convert the fractal derivative model on a smaller scale to an approximate continuous model on a larger scale, so that the model can be easily solved. An optimal filter structure is suggested for minimal pressure drop.

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Cracks in rock mass have always posed a big threat on the durability of fractured rocks in shear zone. Cracking of rock mass in shear zone is a random process, highly variable and influenced by many factors. Cracks in fractured rocks can be repaired by injection of epoxy resin in order to bond the crack and restore its structural integrity. Epoxy resins are used to repairing the shear zone at the Jinping Hydropower Station. An improved polymer grouting material is adopted and the polymerization process is determined. The polymer grouting materials is consisted of resin (component A) and hardener (component B). Polarizing microscopy (PM) tests and mechanical experiments are adopted to evaluate the filling situation of epoxy resin in rock and the mechanical properties of epoxy-repaired rock, respectively. Experimental test results show that, the cracks and pores are filled by epoxy resin, and also the crack surface are boned. The mechanical properties of epoxy-repaired rock are improved by the polymer grouting and the permeability coefficient is decreased.