The drylands of China cover approximately 6.6×106 km2 and are home to approximately 5.8×10^(8)people,providing important ecosystem services for human survival and development.However,dryland ecosystems are e...The drylands of China cover approximately 6.6×106 km2 and are home to approximately 5.8×10^(8)people,providing important ecosystem services for human survival and development.However,dryland ecosystems are extremely fragile and sensitive to external environmental changes.Land use and land cover(LULC)changes significantly impact soil structure and function,thus affecting the soil multifunctionality(SMF).However,the effect of LULC changes on the SMF in the drylands of China has rarely been reported.In this study,we investigated the characteristics of the SMF changes based on soil data in the 1980s from the National Tibetan Plateau Data Center.We explored the drivers of the SMF changes under different LULC types(including forest,grassland,shrubland,and desert)and used structural equation modeling to explore the main driver of the SMF changes.The results showed that the SMF under the four LULC types decreased in the following descending order:forest,grassland,shrubland,and desert.The main driver of the SMF changes under different LULC types was mean annual temperature(MAT).In addition to MAT,pH in forest,soil moisture(SM)and soil biodiversity index in grassland,SM in shrubland,and aridity index in desert are crucial factors for the SMF changes.Therefore,the SMF in the drylands of China is regulated mainly by MAT and pH,and comprehensive assessments of the SMF in drylands need to be performed regarding LULC changes.The results are beneficial for evaluating the SMF among different LULC types and predicting the SMF under global climate change.展开更多
In the present study,CNFs,ZnO and Al2O3 were deposited on the SMFs panels to investigate the deactivation mechanism of Pd-based catalysts in selective acetylene hydrogenation reaction.The examined supports were charac...In the present study,CNFs,ZnO and Al2O3 were deposited on the SMFs panels to investigate the deactivation mechanism of Pd-based catalysts in selective acetylene hydrogenation reaction.The examined supports were characterized by SEM,NH3-TPD and N2adsorption-desorption isotherms to indicate their intrinsic characteristics.Furthermore,in order to understand the mechanism of deactivation,the resulted green oil was characterized using FTIR and SIM DIS.FTIR results confirmed the presence of more unsaturated constituents and then,more branched hydrocarbons formed upon the reaction over alumina-supported catalyst in comparison with the ones supported on CNFs and ZnO,which in turn,could block the pores mouths.Besides the limited hydrogen transfer,N2 adsorption-desorption isotherms results supported that the lowest pore diameters of Al2O3/SMFs close to the surface led to fast deactivation,compared with the other catalysts,especially at higher temperatures.展开更多
The fabrication of LPFG in single mode fiber （SMF） was fabricated using amplitude mask writing techniques. The birefringence effect of LPFG for sensing the transverse strain was discussed in detail. The experimented...The fabrication of LPFG in single mode fiber （SMF） was fabricated using amplitude mask writing techniques. The birefringence effect of LPFG for sensing the transverse strain was discussed in detail. The experimented results shou that it exhibits a very high sensitivity and a good linearity to transverse strain, with a sensitivity some hundred times greater than what has been achieved using FBG sensor.展开更多
基于未知但有界噪声假设的集员滤波器为传统的概率化滤波方法提供了一种可行的替代选择,然而其潜在的计算负担和保守性考虑制约了该方法的实际应用.本文提出一种新的基于保证定界椭球近似的改进集员滤波方法,用于解决针对非线性系统的...基于未知但有界噪声假设的集员滤波器为传统的概率化滤波方法提供了一种可行的替代选择,然而其潜在的计算负担和保守性考虑制约了该方法的实际应用.本文提出一种新的基于保证定界椭球近似的改进集员滤波方法,用于解决针对非线性系统的状态估计问题,在保证实时性的前提下降低了算法的保守性.首先,对非线性模型进行线性化处理,采用DC(Difference of convex)规划方法对线性化误差进行外包定界,并通过椭球近似将其融合到系统噪声中;在此基础上提出了一种结合了椭球直和计算和基于迭代外定界椭球算法的椭球-带交集计算所构成的经典预测-更新步骤来估计得到状态的可行椭球集.与常规的非线性扩展集员滤波方法的仿真比较表明了本文所提出算法的有效性和改进性能.展开更多
基金supported by the Tianshan Talent Training Plan of Xinjiang,China(2022TSYCLJ0058,2022TSYCCX0001)the National Natural Science Foundation of China(2022D01D83,42377358).
文摘The drylands of China cover approximately 6.6×106 km2 and are home to approximately 5.8×10^(8)people,providing important ecosystem services for human survival and development.However,dryland ecosystems are extremely fragile and sensitive to external environmental changes.Land use and land cover(LULC)changes significantly impact soil structure and function,thus affecting the soil multifunctionality(SMF).However,the effect of LULC changes on the SMF in the drylands of China has rarely been reported.In this study,we investigated the characteristics of the SMF changes based on soil data in the 1980s from the National Tibetan Plateau Data Center.We explored the drivers of the SMF changes under different LULC types(including forest,grassland,shrubland,and desert)and used structural equation modeling to explore the main driver of the SMF changes.The results showed that the SMF under the four LULC types decreased in the following descending order:forest,grassland,shrubland,and desert.The main driver of the SMF changes under different LULC types was mean annual temperature(MAT).In addition to MAT,pH in forest,soil moisture(SM)and soil biodiversity index in grassland,SM in shrubland,and aridity index in desert are crucial factors for the SMF changes.Therefore,the SMF in the drylands of China is regulated mainly by MAT and pH,and comprehensive assessments of the SMF in drylands need to be performed regarding LULC changes.The results are beneficial for evaluating the SMF among different LULC types and predicting the SMF under global climate change.
文摘In the present study,CNFs,ZnO and Al2O3 were deposited on the SMFs panels to investigate the deactivation mechanism of Pd-based catalysts in selective acetylene hydrogenation reaction.The examined supports were characterized by SEM,NH3-TPD and N2adsorption-desorption isotherms to indicate their intrinsic characteristics.Furthermore,in order to understand the mechanism of deactivation,the resulted green oil was characterized using FTIR and SIM DIS.FTIR results confirmed the presence of more unsaturated constituents and then,more branched hydrocarbons formed upon the reaction over alumina-supported catalyst in comparison with the ones supported on CNFs and ZnO,which in turn,could block the pores mouths.Besides the limited hydrogen transfer,N2 adsorption-desorption isotherms results supported that the lowest pore diameters of Al2O3/SMFs close to the surface led to fast deactivation,compared with the other catalysts,especially at higher temperatures.
文摘The fabrication of LPFG in single mode fiber （SMF） was fabricated using amplitude mask writing techniques. The birefringence effect of LPFG for sensing the transverse strain was discussed in detail. The experimented results shou that it exhibits a very high sensitivity and a good linearity to transverse strain, with a sensitivity some hundred times greater than what has been achieved using FBG sensor.
文摘基于未知但有界噪声假设的集员滤波器为传统的概率化滤波方法提供了一种可行的替代选择,然而其潜在的计算负担和保守性考虑制约了该方法的实际应用.本文提出一种新的基于保证定界椭球近似的改进集员滤波方法,用于解决针对非线性系统的状态估计问题,在保证实时性的前提下降低了算法的保守性.首先,对非线性模型进行线性化处理,采用DC(Difference of convex)规划方法对线性化误差进行外包定界,并通过椭球近似将其融合到系统噪声中;在此基础上提出了一种结合了椭球直和计算和基于迭代外定界椭球算法的椭球-带交集计算所构成的经典预测-更新步骤来估计得到状态的可行椭球集.与常规的非线性扩展集员滤波方法的仿真比较表明了本文所提出算法的有效性和改进性能.
