Compounds of styrene-butadiene rubber (SBR) filled with bamboo charcoal powders (BCPs) were prepared with a laboratory-sized two-roll mill. The effects of the BCP loading on the curing characteristics and mechanical and thermal properties were investigated. The results indicate that the addition of BCP resulted in a longer curing time and a higher Mooney viscosity in the SBR materials. The incorporation of BCP into SBR improved the mechanical properties and dynamic properties. Furthermore, the mechanical properties of the vulcanizates after thermal aging were also studied, and the experimental results indicate that most of the mechanical properties improved after thermal aging. The overall results indicate that BCP could be used as a cheaper filler for SBR materials.

A B S T R A C TThe chemical residues from sodium hydrosulfite production contain complex chemical composition and give out a bad odor posing a grave threat to the environment and public health. The organic residues containing thiodiglycol, 2,2´-dithiodiethanol, and 1,4-thioxane are suitable for high pressure lubrication applications. In this paper, the chemical residues were recycled and used to prepare the solid lubricant for drilling fluids. The lubricity of solid lubricant was illustrated and the experimental results indicated that the solid lubricant could improve lubricity of drilling fluids, which had met the requirement of industrial applications. Experimental studies were also performed on its salt resistance, temperature resistance, and compatibility. The solid lubricant had passed pilot experiments and been used in the Changqing and Dagang oil fields in China. This study not only enables recycling of industrial products but also makes the clean production come true, which contributed to environment protection.

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A parameterization Hopf bifurcation controller is proposed for the equivalent nonlinear dynamic system of brushless DC motor, in this paper. The designed controller is consisted of vector field of the polynomial system and it is not change the equilibria of the original system. Compared with existing controllers, it is simpler and more general in form. Using the Hurwitz criterion and cylindrical algebraic decomposition (CAD), the controller parameters are calculated. Numerical simulations on the brushless DC motor system illustrate the effectiveness of the approach. Index Terms -Hopf bifurcation, Brushless DC motor controller, Cylindrical algebraic decomposition (CAD).

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