Internal reformation of low steam methane fuel is important for the high efficiency and low cost operation of solid oxide fuel cell. Understanding and overcoming carbon deposition is crucial for the technology develop...Internal reformation of low steam methane fuel is important for the high efficiency and low cost operation of solid oxide fuel cell. Understanding and overcoming carbon deposition is crucial for the technology development. Here a multi-physics model is established for the relevant experimental cells. Balance of electrochemical potentials for the electrochemical reactions, generic rate expression for the methane steam reforming, dusty gas model in a form of Fick＇s model for anode gas transport are used in the model. Excellent agreement between the theoretical and experimental current-voltage relations is obtained, demonstrating the validity of the proposed theoretical model. The steam reaction order in low steam methane reforming reaction is found to be 1. Detailed information about the distributions of physical quantities is obtained by the numerical simulation. Carbon deposition is analyzed in detail and the mechanism for the coking inhibition by operating current is illustrated clearly. Two expressions of carbon activity are analyzed and found to be correct qualitatively, but not quantitatively. The role of anode diffusion layer on reducing the current threshold for carbon removal is also explained. It is noted that the current threshold reduction may be explained quantitatively with the carbon activity models that are only qualitatively correct.展开更多
The regularization contributes to the resolution and stability in geophysical inversion. The authors apply dual-parameter shaping regularization to full waveform inversion, aiming at two points ： （ 1 ） improving th...The regularization contributes to the resolution and stability in geophysical inversion. The authors apply dual-parameter shaping regularization to full waveform inversion, aiming at two points ： （ 1 ） improving the boundary resolution, and （2） increasing convergence. Firstly, the forward modeling is done, and the inversion is processed with the optimal solution. Compared with classical Tikhonov regularization scheme, the method re fleets better resolution and stronger convergence. Then, Marmousi model is experimented and inversed, and the deep structure has a sharper outline. The phase residual comparison illustrates weaker cycle-slipping. And a choice scheme of parameter is applied in FWI.展开更多
The base stress of the opened bottom cylinder structure differs greatly from that of the structure with a closed bottom. By investigating the inner soil pressure on the cylinder wall and the base stress of the cylinde...The base stress of the opened bottom cylinder structure differs greatly from that of the structure with a closed bottom. By investigating the inner soil pressure on the cylinder wall and the base stress of the cylinder base, which were obtained from the model experiments, the interactions among the filler inside the cylinder, subsoil and cylinder are analyzed. The adjusting mechanism of frictional resistance between the inner filler and the wall of the cylinder during the overturning of the cylinder is discussed. Based on the experimental study, a method for calculating the base stress of the opened bottom cylinder structure is proposed. Meanwhile, the formulas for calculating the effective anti-overturning ratio of the opened bottom cylinder are derived.展开更多
Connected individuals(ramets)of clonal plants are frequently fragmented due to disturbance,and such clonal fragmentation may influence their growth.However,it is unclear whether different patterns of clonal fragmentat...Connected individuals(ramets)of clonal plants are frequently fragmented due to disturbance,and such clonal fragmentation may influence their growth.However,it is unclear whether different patterns of clonal fragmentation produce differential effects on plant growth and whether such differences vary with genotypes.We collected one group of connected ramets of the stoloniferous floating invasive macrophyte Pistia stratiotes from each of six provinces(Guangdong,Guangxi,Hubei,Jiangsu,Sichuan and Yunnan Provinces)of China,and assumed that these ramets belonged to different genotypes.After several generations of vegetative propagation to remove potential parental effects,new ramets(hereafter referred to as parent ramets)from each of these assumed genotypes were subjected to four patterns of clonal fragmentation,i.e.,all offspring ramets produced during the experiment remained connected to their parent ramet(control),or the primary(1°),secondary(2°)or tertiary(3°)offspring ramets were disconnected from their parent ramet.We found significant growth differences among the assumed genotypes,confirming that the ramets sampled from these six provinces were from different genotypes.Compared with the control,disconnecting the 1°,2°or 3°ramets did not significantly affect biomass of the whole clone(i.e.,the parent ramet plus all offspring ramets)of P.stratiotes.Disconnecting the 1°ramets significantly increased biomass of the parental ramet of all six genotypes compared with the control.However,disconnecting the 2°or 3°ramets had little effect on biomass of the parent ramet for all genotypes except the Guangxi genotype,for which disconnecting the 2°ramets decreased biomass of the parent ramet.Disconnecting the 1°,2°or 3°ramets had no impact on biomass or number of the 1°or the 3°ramets for any of the genotypes.However,disconnecting the 1°ramets decreased biomass of the 2°ramets for the Guangdong and Yunnan genotypes,but had no effect for the other four genotypes.We conclude that different patterns of clonal fragmentation can have different impacts on parent and offspring ramets of P.stratiotes and such an impact may vary with genotypes.展开更多
How to integrate and disseminate globally distributed multi-source and heterogeneous spatial information is an open problem in integration and sharing service of geographic information. Here we propose a new service a...How to integrate and disseminate globally distributed multi-source and heterogeneous spatial information is an open problem in integration and sharing service of geographic information. Here we propose a new service architecture suitable for integra- tion and sharing of distributed multi-source geographic information. We also propose a global virtual pyramid model, which can be applied in 3D virtual globes. In view of the difficulty of web multi-node geographic information sharing service, we propose a web multi-node service aggregation method, integrated in our autonomously developed virtual globe platform Geo- Globe and introduced in the National Platform for Common GeoSpatial Information Services named ＂T1ANDITU＂. It achieves 2D and 3D integration for geographic information service.展开更多
基金This work was supported by the National Basic Research Program of China （No.2012CB215405）, the National Natural Science Foundation of China （No.11374272）, and the Specialized Research Fund for the Doctoral Program of Higher Education （No.20123402110064）.
文摘Internal reformation of low steam methane fuel is important for the high efficiency and low cost operation of solid oxide fuel cell. Understanding and overcoming carbon deposition is crucial for the technology development. Here a multi-physics model is established for the relevant experimental cells. Balance of electrochemical potentials for the electrochemical reactions, generic rate expression for the methane steam reforming, dusty gas model in a form of Fick＇s model for anode gas transport are used in the model. Excellent agreement between the theoretical and experimental current-voltage relations is obtained, demonstrating the validity of the proposed theoretical model. The steam reaction order in low steam methane reforming reaction is found to be 1. Detailed information about the distributions of physical quantities is obtained by the numerical simulation. Carbon deposition is analyzed in detail and the mechanism for the coking inhibition by operating current is illustrated clearly. Two expressions of carbon activity are analyzed and found to be correct qualitatively, but not quantitatively. The role of anode diffusion layer on reducing the current threshold for carbon removal is also explained. It is noted that the current threshold reduction may be explained quantitatively with the carbon activity models that are only qualitatively correct.
文摘The regularization contributes to the resolution and stability in geophysical inversion. The authors apply dual-parameter shaping regularization to full waveform inversion, aiming at two points ： （ 1 ） improving the boundary resolution, and （2） increasing convergence. Firstly, the forward modeling is done, and the inversion is processed with the optimal solution. Compared with classical Tikhonov regularization scheme, the method re fleets better resolution and stronger convergence. Then, Marmousi model is experimented and inversed, and the deep structure has a sharper outline. The phase residual comparison illustrates weaker cycle-slipping. And a choice scheme of parameter is applied in FWI.
文摘The base stress of the opened bottom cylinder structure differs greatly from that of the structure with a closed bottom. By investigating the inner soil pressure on the cylinder wall and the base stress of the cylinder base, which were obtained from the model experiments, the interactions among the filler inside the cylinder, subsoil and cylinder are analyzed. The adjusting mechanism of frictional resistance between the inner filler and the wall of the cylinder during the overturning of the cylinder is discussed. Based on the experimental study, a method for calculating the base stress of the opened bottom cylinder structure is proposed. Meanwhile, the formulas for calculating the effective anti-overturning ratio of the opened bottom cylinder are derived.
基金We thank the three anonymous reviewers for their valuable comments and the support from the National Natural Science Foundation of China(grant 31800341).
文摘Connected individuals(ramets)of clonal plants are frequently fragmented due to disturbance,and such clonal fragmentation may influence their growth.However,it is unclear whether different patterns of clonal fragmentation produce differential effects on plant growth and whether such differences vary with genotypes.We collected one group of connected ramets of the stoloniferous floating invasive macrophyte Pistia stratiotes from each of six provinces(Guangdong,Guangxi,Hubei,Jiangsu,Sichuan and Yunnan Provinces)of China,and assumed that these ramets belonged to different genotypes.After several generations of vegetative propagation to remove potential parental effects,new ramets(hereafter referred to as parent ramets)from each of these assumed genotypes were subjected to four patterns of clonal fragmentation,i.e.,all offspring ramets produced during the experiment remained connected to their parent ramet(control),or the primary(1°),secondary(2°)or tertiary(3°)offspring ramets were disconnected from their parent ramet.We found significant growth differences among the assumed genotypes,confirming that the ramets sampled from these six provinces were from different genotypes.Compared with the control,disconnecting the 1°,2°or 3°ramets did not significantly affect biomass of the whole clone(i.e.,the parent ramet plus all offspring ramets)of P.stratiotes.Disconnecting the 1°ramets significantly increased biomass of the parental ramet of all six genotypes compared with the control.However,disconnecting the 2°or 3°ramets had little effect on biomass of the parent ramet for all genotypes except the Guangxi genotype,for which disconnecting the 2°ramets decreased biomass of the parent ramet.Disconnecting the 1°,2°or 3°ramets had no impact on biomass or number of the 1°or the 3°ramets for any of the genotypes.However,disconnecting the 1°ramets decreased biomass of the 2°ramets for the Guangdong and Yunnan genotypes,but had no effect for the other four genotypes.We conclude that different patterns of clonal fragmentation can have different impacts on parent and offspring ramets of P.stratiotes and such an impact may vary with genotypes.
基金supported by the National Natural Science Foundation of China(Grant No.41023001)National Basic Research Program of China(Grant No.2012CB719906)Innovative Research Groups Supported Project of the National Natural Science Foundation of China(Grant No.41021061)
文摘How to integrate and disseminate globally distributed multi-source and heterogeneous spatial information is an open problem in integration and sharing service of geographic information. Here we propose a new service architecture suitable for integra- tion and sharing of distributed multi-source geographic information. We also propose a global virtual pyramid model, which can be applied in 3D virtual globes. In view of the difficulty of web multi-node geographic information sharing service, we propose a web multi-node service aggregation method, integrated in our autonomously developed virtual globe platform Geo- Globe and introduced in the National Platform for Common GeoSpatial Information Services named ＂T1ANDITU＂. It achieves 2D and 3D integration for geographic information service.
