Nanodiamonds with sizes of 3–6nm were prepared by irradiating graphite suspension using a long-pulse-width (1.2ms) laser at room temperature and normal pressure. The low power density and long pulse laser generated a lower temperature and a lower pressure, which determine the stable size of nanodiamonds. On the other hand, the low degree of supercooling allows a rather low growth velocity, and a disordered structure formed at the diamond surface retards the epitaxy growth. The above two factors dynamically limit the final size of nanodiamonds. Our results suggest that the growth of nanodiamonds follows the Wilson-Frenkel law, and the long pulse laser is propitious to producing fine nanodiamonds.

Pervious concrete is an environmentally friendly material that improves water permeability, skid resistance, and sound absorption characteristics. Permeability is the most important functional performance for the pervious concrete while limited studies have been conducted to predict permeability based on mix-design parameters. This study proposed a method to combine the beetle antennae search (BAS) and random forest (RF) algorithm to predict the permeability of pervious concrete. Based on the 36 samples designed in the laboratory and 4 key influencing variables, the permeability of pervious concrete can be obtained by varying mix-design parameters by RF. BAS algorithm was used to tune the hyperparameters of RF, which were then verified by the so-called 10-fold cross-validation. Furthermore, the model to combine the BAS and RF was validated by the correlation parameters. The results showed that the hyperparameters of RF can be tuned by the BAS efficiently; the BAS can combine the conventional RF algorithm to construct the evolved model to predict the permeability of pervious concrete; the cement/aggregate ratio was the most significant variable to determine the permeability, followed by the coarse aggregate proportions.

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Vibrations induced by traffic are of concern for the slope stability of the open-pit mine. Different solutions to mitigate this phenomenon are under investigation. In the field of pavement engineering, the so-called antivibration paving technologies are under investigation in order to avoid the generation of excessive vibration and contains propagation. To more fully examine the effectiveness and potential of the antivibration pavement in the application of vibration absorbing for the open-pit mines, numerical simulations based on a two-dimensional (2D) finite element (FE) model were conducted. Sensitivity analysis of varying monitored points and varying loads are performed. Several important parameters such as the damping layer position and thickness and damping ratio are evaluated as well. By using this FE simulation to model the vibration response induced by traffic, the costly construction mistakes and field experimentation can be avoided.

Cr 3 C 2 -Ni composite coatings were fabricated on Ti-6Al-4V substrate by laser cladding using powder mixture of NiCrBSiC alloy and Cr 3 C 2 . Results of the analysis show that the microstructure and microhardness of the coatings depend strongly on the specific laser energy. With a relatively low specific laser energy (133?3 J mm 22 ), Cr 3 C 2 particles were partially dissolved into melted Ni based alloy, and the coating was formed of undissolved Cr 3 C 2 particles and cannular Cr 23 C 6 uniformly distributed in cellular c-Ni and eutectic matrix. With a higher specific laser energy (266?7 J mm 22 ), more Cr 3 C 2 particles were dissolved, and the coating consisted of c-Ni, TiC dendrites and lamellar CrB. When the specific laser energy is 133?3 and 266?7 J mm 22 , the microhardness of the coating is 500-700 HV and 700-1000 HV, respectively.

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