In this work,Bi-based catalysts were prepared by one pot method(PM)and incipient wetness impregnation method(IM)and preparation conditions of the PM were researched.Catalytic activity of catalysts was evaluated using ...In this work,Bi-based catalysts were prepared by one pot method(PM)and incipient wetness impregnation method(IM)and preparation conditions of the PM were researched.Catalytic activity of catalysts was evaluated using a fixed-bed reactor for acetylene hydrochlorination.The results displayed that the PM catalyst was prepared at 160℃for 2 h possessed a superior catalytic performance compared to the IM catalyst.The characterizations of XRD,BET,EDS and SEM demonstrated that the PM catalyst was microspheres structure,which could provide richer channel structures,larger specific surface areas and more active centres,thus improving the catalytic performances of catalysts.In addition,carbon deposition in the reaction was a possible reason for Bi-based catalysts deactivation.展开更多
In this study, we developed a computer program for automatic prediction of watering time point by considering the environmental factors such as solar radiation, air temperature and relative humidity based on the multi...In this study, we developed a computer program for automatic prediction of watering time point by considering the environmental factors such as solar radiation, air temperature and relative humidity based on the multiple linear regression equation of leaf area and Penman Method. The experiments were carried out for a year in two watering experimental plots, one of which was controlled by pF value, and the other by the computer program. After comparing the results of the two plots, the following findings were obtained. In the computer program plot, the observed and predicted values of both leaf area and evapotranspiration indicated significant correlation at the 1% level, which suggested that the computer program had high prediction accuracy. In addition, no significant difference was observed between the two experimental plots with respects to the plant height, plant diameter, leaf area, leaf number, fresh weight, and dry weight, which demonstrated that the plants in the computer program plot had normal growth. On the other hand, although the number of flower buds and flowering shoots showed higher values at the end of certain cultivations in the computer program plot than those in pF value plot, we proposed that it was due to the effect of cumulative daily solar radiation in the greenhouse, rather than the watering. Thus, we have reached the conclusion that the computer program for automatic prediction of watering time point developed by this study has high applicability in miniature pot rose production.展开更多
为获得高层建筑围护结构设计风荷载,通常需要考虑其表面风压系数的概率特征,进而进行极值估计。针对当前基于超越阈值模型的风压系数极值估计方法存在阈值选取困难,需要较大样本的不足,基于高层建筑标准模型进行风洞试验,首先研究其表...为获得高层建筑围护结构设计风荷载,通常需要考虑其表面风压系数的概率特征,进而进行极值估计。针对当前基于超越阈值模型的风压系数极值估计方法存在阈值选取困难,需要较大样本的不足,基于高层建筑标准模型进行风洞试验,首先研究其表面风压系数的概率特征,结果表明迎风区测点接近高斯分布,分离区测点风压系数母体接近Gamma分布,风压系数极小值接近GEV(general extreme value,GEV)分布;提出一种改进的POT(peak over threshold,POT)极值估计方法进行表面风压系数极值估计,进而与几种传统极值估计方法进行对比,结果表明改进POT极值估计方法可实现小样本的风压系数极值估计,其估计结果与大样本容量的标准极值偏差小于5%,且稳定性较好;最后给出了标准高层建筑模型表面极值风压系数。展开更多
A simple one-pot non-isocyanate route for synthesizing thermoplastic polyureas is presented. In situ urethanization was conducted from the ring-opening reaction of ethylene carbonate with poly(propylene glycol) bis(2-...A simple one-pot non-isocyanate route for synthesizing thermoplastic polyureas is presented. In situ urethanization was conducted from the ring-opening reaction of ethylene carbonate with poly(propylene glycol) bis(2-aminopropyl ether) and hexanediamine,m-xylylenediamine, or diethylene glycol bis(3-aminopropyl) ether at 100 °C for 6 h under normal pressure. Melt transurethane polycondensation was successively conducted at 170 °C under a reduced pressure of 399 Pa for different time periods. A series of nonisocyanate thermoplastic polyureas(NI-TPUreas) were prepared. The NI-TPUreas were characterized by gel permeation chromatography,FTIR, 1 H-NMR, differential scanning calorimetry, thermogravimetric analysis, wide-angle X-ray diffraction, atomic force microscopy,and tensile test. NI-TPUreas exhibited Mn of up to 1.67 × 104 g/mol, initial decomposition temperature over 290 °C, and tensile strength of up to 32 MPa. Several crystallizable NI-TPUreas exhibited Tm exceeding 98 °C. NI-TPUreas with good thermal and mechanical properties were prepared through a green and simple one-pot non-isocyanate route.展开更多
The title compound was synthesized by a one pot synthesis method with ethanolamine ,ketone and dichloroacetyl chloride. The product was characterization by IR, 1 HNMR,UV, and elementary analysis.
基金Natural Scientific Foundation of China(21263025,U1403293)
文摘In this work,Bi-based catalysts were prepared by one pot method(PM)and incipient wetness impregnation method(IM)and preparation conditions of the PM were researched.Catalytic activity of catalysts was evaluated using a fixed-bed reactor for acetylene hydrochlorination.The results displayed that the PM catalyst was prepared at 160℃for 2 h possessed a superior catalytic performance compared to the IM catalyst.The characterizations of XRD,BET,EDS and SEM demonstrated that the PM catalyst was microspheres structure,which could provide richer channel structures,larger specific surface areas and more active centres,thus improving the catalytic performances of catalysts.In addition,carbon deposition in the reaction was a possible reason for Bi-based catalysts deactivation.
基金supported by the Science Founda-tion of Guangxi Zhuang Autonomous Region, China(0832002)
文摘In this study, we developed a computer program for automatic prediction of watering time point by considering the environmental factors such as solar radiation, air temperature and relative humidity based on the multiple linear regression equation of leaf area and Penman Method. The experiments were carried out for a year in two watering experimental plots, one of which was controlled by pF value, and the other by the computer program. After comparing the results of the two plots, the following findings were obtained. In the computer program plot, the observed and predicted values of both leaf area and evapotranspiration indicated significant correlation at the 1% level, which suggested that the computer program had high prediction accuracy. In addition, no significant difference was observed between the two experimental plots with respects to the plant height, plant diameter, leaf area, leaf number, fresh weight, and dry weight, which demonstrated that the plants in the computer program plot had normal growth. On the other hand, although the number of flower buds and flowering shoots showed higher values at the end of certain cultivations in the computer program plot than those in pF value plot, we proposed that it was due to the effect of cumulative daily solar radiation in the greenhouse, rather than the watering. Thus, we have reached the conclusion that the computer program for automatic prediction of watering time point developed by this study has high applicability in miniature pot rose production.
文摘为获得高层建筑围护结构设计风荷载,通常需要考虑其表面风压系数的概率特征,进而进行极值估计。针对当前基于超越阈值模型的风压系数极值估计方法存在阈值选取困难,需要较大样本的不足,基于高层建筑标准模型进行风洞试验,首先研究其表面风压系数的概率特征,结果表明迎风区测点接近高斯分布,分离区测点风压系数母体接近Gamma分布,风压系数极小值接近GEV(general extreme value,GEV)分布;提出一种改进的POT(peak over threshold,POT)极值估计方法进行表面风压系数极值估计,进而与几种传统极值估计方法进行对比,结果表明改进POT极值估计方法可实现小样本的风压系数极值估计,其估计结果与大样本容量的标准极值偏差小于5%,且稳定性较好;最后给出了标准高层建筑模型表面极值风压系数。
基金financially supported by the National Natural Science Foundation of China (No. 21244006)Beijing Natural Science Foundation (No. 2182056)
文摘A simple one-pot non-isocyanate route for synthesizing thermoplastic polyureas is presented. In situ urethanization was conducted from the ring-opening reaction of ethylene carbonate with poly(propylene glycol) bis(2-aminopropyl ether) and hexanediamine,m-xylylenediamine, or diethylene glycol bis(3-aminopropyl) ether at 100 °C for 6 h under normal pressure. Melt transurethane polycondensation was successively conducted at 170 °C under a reduced pressure of 399 Pa for different time periods. A series of nonisocyanate thermoplastic polyureas(NI-TPUreas) were prepared. The NI-TPUreas were characterized by gel permeation chromatography,FTIR, 1 H-NMR, differential scanning calorimetry, thermogravimetric analysis, wide-angle X-ray diffraction, atomic force microscopy,and tensile test. NI-TPUreas exhibited Mn of up to 1.67 × 104 g/mol, initial decomposition temperature over 290 °C, and tensile strength of up to 32 MPa. Several crystallizable NI-TPUreas exhibited Tm exceeding 98 °C. NI-TPUreas with good thermal and mechanical properties were prepared through a green and simple one-pot non-isocyanate route.
文摘The title compound was synthesized by a one pot synthesis method with ethanolamine ,ketone and dichloroacetyl chloride. The product was characterization by IR, 1 HNMR,UV, and elementary analysis.
