：In the present work, tin-sulfur based catalysts was prepared using Na 2 SO 3 and (CH 3 SO 3) 2 Sn and was tested in acetylene hydrochlorination. Based on the analysis of experiments results, the acetylene conversion of (CH 3 SO 3) 2 Sn/S@AC is still over 90% after 50 h reaction, at the reaction condition of T = 200 o C, V HCl /V C2H2 = 1.1:1.0 and C 2 H 2-GSHV = 15 h-1. According to the results of X-ray photoelectron spectroscopy (XPS), HCl adsorption experiments, and acetylene temperature programmed desorption (C 2 H 2-TPD), it is reasonable concluded that the interaction between Sn and S not only can retard the oxidation of Sn 2+ in catalysts but also strengthen the reactant adsorption capacity of tin-based catalysts. Furthermore, results obtained from nitrogen adsorption/desorption and XPS proved that the CH 3 SO 3-can effectively decrease the coke deposition of (CH 3 SO 3) 2 Sn/AC and thus prolong the lifetime of (CH 3 SO 3) 2 Sn/AC.

In practice, gear backlash and bearing clearance usually exist together in a gear system. They may induce complicated dynamic responses and degrade transmission performance. Up to now, although each of them has been researched, little attention has been paid to the coupling dynamic characteristics of gear backlash and bearing clearance. In a limited number of relevant studies, since the linear collision models they adopted are difficult to realistically depict actual collision behaviors caused by bearing clearance, these studies cannot accurately reveal the coupling dynamic characteristics of gear backlash and bearing clearance. Furthermore, system stability of the gear system considering gear backlash and bearing clearance has not been thoroughly investigated. In view of this, this paper contributes to the research on dynamic modeling and stability analysis for the spur gear system considering gear backlash and bearing clearance. A nonlinear collision model with time-varying contact stiffness/damping is suggested for describing the bearing collision behaviors. Based on the geometrical relationship of dynamic center distance, dynamic working pressure angle, and dynamic backlash, the coupling motion model of gear backlash and bearing clearance is developed. On this basis, the dynamic model of the spur gear system considering gear backlash and bearing clearance is established and verified by numerical simulations, virtual prototyping simulations and experiments. Afterwards, to thoroughly explore the complicated dynamic characteristics of the gear system considering gear backlash and bearing clearance, several important parameters, i.e., rotational speed, gear backlash and bearing clearance, are chosen as bifurcation parameters to study their influences on system stability via bifurcation diagrams, time-domain waveforms, FFT spectra, Poincaré maps, and phase diagrams. Various complicated nonlinear behaviors, such as hopping, multiple periodic motion, quasi-periodic motion, and chaotic motion, are revealed. This study can provide useful reference for the multi-clearance coupling research of the gear system in complicated working environments.

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Abstract. Traditional solvents method and response surface methodology (RSM) for the pilot plant extraction of polysaccharides from mulberry leaves were studied. The effects of three extraction factors (temperature, extraction time and sample: solvent ratio) on the yield of polysaccharides were examined. Three factors-three level Box-Behnken response surface design (BBD) coupled with RSM were used to find the optimal experimental conditions by reducing the number of experiments performed. The results indicated that the optimum pilot-plant conditions for the extraction of polysaccharides are a temperature of 76.7 ºC, an extraction time of 1.87 h (112.2 min) and a sample: solvent (distilled water) ratio of 1:20.6. The actual measured concentration under these optimized conditions is 105.57 mg/g polysaccharide crude product and is basically consistent with the predicted value of 106.64 mg/g. These show that the BBD coupled with RSM to model the pilot plant process of polysaccharides from mulberry leaves were accurate and reliable. The pilot-plant results are compared with those of the laboratory extraction which lay the foundation for the industrial application.