Controlling catalytic activities through surface strain engineering remains a hot topic in electrocatalysis studies.Herein,ab initio molecular dynamics(AIMD)simulation associated with free energy sampling technology w...Controlling catalytic activities through surface strain engineering remains a hot topic in electrocatalysis studies.Herein,ab initio molecular dynamics(AIMD)simulation associated with free energy sampling technology were performed to study the energetics of the key step of producing C2 products in electrocatalytic reduction of CO or CO_(2),i.e.CO dimerization,on strained Cu(100)with an explicit aqueous solvent model.It is worth mentioning that when compressive strain reaches a certain extent,the surface of Cu(100)will undergo reconstruction.We showed that,from tensile to compressive strain,the free energy barrier of CO dimerization decreased,suggesting that the activity of CO dimerization increases.It was also found that some of the reconstructed surfaces showing the lowest free energy barriers but might be less stable can be stabilized in the presence of adsorbed O or CO.Upon detailed quantitative analysis on the charges of surface Cu atoms,we found that the free energy barriers were strongly correlated with the charge of Cu atoms where the OCCO intermediate adsorbs.When the surfaces structures of Cu(100)were altered under compressive strain,the electronic structure of surface Cu atoms was monitored and thus the activity of electrocatalytic CO dimerization can be tuned.展开更多
New global three dimensional potential energy surfaces for the Cl＋H2 reactive system have been constructed using accurate multireference configuration interaction calculations with a large basis set. The three lowest...New global three dimensional potential energy surfaces for the Cl＋H2 reactive system have been constructed using accurate multireference configuration interaction calculations with a large basis set. The three lowest adiabatic potential energy surfaces correlating asymptotically with Cl（^2p）＋H2 have been transformed to adiabatic representation, which leads to a fourth coupling potential for non-linear geometries. In addition, the spin-orbit coupling surfaces have also been computed using the Breit-Pauli Hamiltonian. Properties of the new potential are described. Reaction dynamics based on the new potential agrees with the recent experimental results quite well.展开更多
The salinity boundary condition at the ocean surface plays an important role in the stability of long-term integrations of an oceanic general circulation model （OGCM） and in determining its equilibrium solutions. Th...The salinity boundary condition at the ocean surface plays an important role in the stability of long-term integrations of an oceanic general circulation model （OGCM） and in determining its equilibrium solutions. This study presents a new formulation of the salt flux calculation at the ocean surface based on physical processes of salt exchange at the air-sea interface. The formulation improves the commonly used virtual salt flux with constant reference salinity by allowing for spatial correlations between surface freshwater flux and sea-surface salinity while preserving the conservation of global salinity. The new boundary condition is implemented in the latest version of the National Key Laboratory of NumericaI Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics/Institute of Atmospheric Physics Climate Ocean Model version 2 （LICOM2.0）. The impact of the new boundary condition on the equilibrium simulations of the model is presented. It is shown that the new formulation leads to a stronger Atlantic meridional overturning circulation （AMOC） that is closer to observational estimates. It also slightly improves poleward heat transport by the oceans in both the Atlantic and the global oceans.展开更多
TYPES OF ARTICLES1.Research articles Research articles belong to the full length article type,and should include elements as follows：title,running title,and byline;correspondent footnote;abstract and keywords;introdu...TYPES OF ARTICLES1.Research articles Research articles belong to the full length article type,and should include elements as follows：title,running title,and byline;correspondent footnote;abstract and keywords;introduction;materials and methods;results;discussion;acknowledgements;compliance;author contributions;references;figure legends and figures/tables.展开更多
Shape-from-shading(SFS) is one of the important approaches of 3-D surface reconstruction in computer vision. Since reflectance map equation in SFS is a nonlinear partial differential equation(PDE) with two unknown var...Shape-from-shading(SFS) is one of the important approaches of 3-D surface reconstruction in computer vision. Since reflectance map equation in SFS is a nonlinear partial differential equation(PDE) with two unknown variables, SFS with one image is ill-posed in mathematical sense. A linear perspective SFS method with two images is proposed to deal with the problem. We assume that two images with different light source directions are captured firstly. Orthogonal projection is not as accurate as perspective one to simulate imaging processes. Two reflectance map equations are established based on the Lambertian model under perspective projection, and the equations are further transformed into one linear PDE. Then the iterative semi-Lagrangian algorithm is used to approximate the solution. Finally, 3-D height values of pixel points in imaging planes are solved by the numerical interpolation method. Experimental results of both hemisphere and complex surfaces show that the proposed method can reconstruct surfaces accurately.展开更多
A new method for the retrieval of ocean wave parameters from SAR imagery is developed,based on the shape-from-shading(SFS)technique.Previously,the SFS technique has been used in the reconstruction of 3D landform infor...A new method for the retrieval of ocean wave parameters from SAR imagery is developed,based on the shape-from-shading(SFS)technique.Previously,the SFS technique has been used in the reconstruction of 3D landform information from SAR images,in order to generate elevation maps of topography for land surfaces.Here,in order to retrieve ocean wave characteristics,we apply the SFS methodology,together with a method to orient the angular measurements of the azimuth slope and range slope,in the measurement of ocean surface waves.This method is applied to high resolution fine-quad polarization mode(HH,VV,VH and HV)C-band RADARSAT-2 SAR imagery,in order to retrieve ocean wave spectra and extract wave parameters.Collocated in situ buoy measurements are used to validate the reliability of this method.Results show that the method can reliably estimate wave height,dominant wave period,dominant wave length and dominant wave direction from C-band SAR images.The advantage of this method is that it does not depend on modulation transfer functions(MTFs),in order to measure ocean surface waves.This method can be used in monitoring ocean surface wave propagation through open water areas into ice-covered areas,especially the marginal ice zone(MIZ)in polar oceans.展开更多
文摘Controlling catalytic activities through surface strain engineering remains a hot topic in electrocatalysis studies.Herein,ab initio molecular dynamics(AIMD)simulation associated with free energy sampling technology were performed to study the energetics of the key step of producing C2 products in electrocatalytic reduction of CO or CO_(2),i.e.CO dimerization,on strained Cu(100)with an explicit aqueous solvent model.It is worth mentioning that when compressive strain reaches a certain extent,the surface of Cu(100)will undergo reconstruction.We showed that,from tensile to compressive strain,the free energy barrier of CO dimerization decreased,suggesting that the activity of CO dimerization increases.It was also found that some of the reconstructed surfaces showing the lowest free energy barriers but might be less stable can be stabilized in the presence of adsorbed O or CO.Upon detailed quantitative analysis on the charges of surface Cu atoms,we found that the free energy barriers were strongly correlated with the charge of Cu atoms where the OCCO intermediate adsorbs.When the surfaces structures of Cu(100)were altered under compressive strain,the electronic structure of surface Cu atoms was monitored and thus the activity of electrocatalytic CO dimerization can be tuned.
基金V. ACKNOWLEDGMENTS This work was supported by the National Natural Science Foundation of China （No.20725312 and No.20533060） and the Ministry of Science and Technology （No.2007CB815201）.
文摘New global three dimensional potential energy surfaces for the Cl＋H2 reactive system have been constructed using accurate multireference configuration interaction calculations with a large basis set. The three lowest adiabatic potential energy surfaces correlating asymptotically with Cl（^2p）＋H2 have been transformed to adiabatic representation, which leads to a fourth coupling potential for non-linear geometries. In addition, the spin-orbit coupling surfaces have also been computed using the Breit-Pauli Hamiltonian. Properties of the new potential are described. Reaction dynamics based on the new potential agrees with the recent experimental results quite well.
基金supported by the National Major Research High Performance Computing Program of China(Grant No.2016 YFB0200800)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No. XDA11010403)+1 种基金the National Natural Science Foundation of China(Grant No.41305028)and the Key Research Program of Frontier Sciences,Chinese Academy of Sciences(Grant No.QYZDY-SSW-DQC002)
文摘The salinity boundary condition at the ocean surface plays an important role in the stability of long-term integrations of an oceanic general circulation model （OGCM） and in determining its equilibrium solutions. This study presents a new formulation of the salt flux calculation at the ocean surface based on physical processes of salt exchange at the air-sea interface. The formulation improves the commonly used virtual salt flux with constant reference salinity by allowing for spatial correlations between surface freshwater flux and sea-surface salinity while preserving the conservation of global salinity. The new boundary condition is implemented in the latest version of the National Key Laboratory of NumericaI Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics/Institute of Atmospheric Physics Climate Ocean Model version 2 （LICOM2.0）. The impact of the new boundary condition on the equilibrium simulations of the model is presented. It is shown that the new formulation leads to a stronger Atlantic meridional overturning circulation （AMOC） that is closer to observational estimates. It also slightly improves poleward heat transport by the oceans in both the Atlantic and the global oceans.
文摘TYPES OF ARTICLES1.Research articles Research articles belong to the full length article type,and should include elements as follows：title,running title,and byline;correspondent footnote;abstract and keywords;introduction;materials and methods;results;discussion;acknowledgements;compliance;author contributions;references;figure legends and figures/tables.
基金supported by the National Natural Science Foundation of China(61005015)the Third National Post-Doctoral Special Foundation of China(201003280)
文摘Shape-from-shading(SFS) is one of the important approaches of 3-D surface reconstruction in computer vision. Since reflectance map equation in SFS is a nonlinear partial differential equation(PDE) with two unknown variables, SFS with one image is ill-posed in mathematical sense. A linear perspective SFS method with two images is proposed to deal with the problem. We assume that two images with different light source directions are captured firstly. Orthogonal projection is not as accurate as perspective one to simulate imaging processes. Two reflectance map equations are established based on the Lambertian model under perspective projection, and the equations are further transformed into one linear PDE. Then the iterative semi-Lagrangian algorithm is used to approximate the solution. Finally, 3-D height values of pixel points in imaging planes are solved by the numerical interpolation method. Experimental results of both hemisphere and complex surfaces show that the proposed method can reconstruct surfaces accurately.
基金This work was supported by the National Natural Science Foundation of China(Grant NO.41276187)the Global Change Research Program of China(Grant No.2015CB953901)+3 种基金the Startup Foundation for Introducing Talent of NUIST(Grant No.20110310)Program for Innovation Research and Entrepreneurship Team in Jiangsu Provincethe CFOSAT project,the Canadian Program on Energy Research and Developmentthe Canadian Space Agency GRIP program funding for wave-ice interactions
文摘A new method for the retrieval of ocean wave parameters from SAR imagery is developed,based on the shape-from-shading(SFS)technique.Previously,the SFS technique has been used in the reconstruction of 3D landform information from SAR images,in order to generate elevation maps of topography for land surfaces.Here,in order to retrieve ocean wave characteristics,we apply the SFS methodology,together with a method to orient the angular measurements of the azimuth slope and range slope,in the measurement of ocean surface waves.This method is applied to high resolution fine-quad polarization mode(HH,VV,VH and HV)C-band RADARSAT-2 SAR imagery,in order to retrieve ocean wave spectra and extract wave parameters.Collocated in situ buoy measurements are used to validate the reliability of this method.Results show that the method can reliably estimate wave height,dominant wave period,dominant wave length and dominant wave direction from C-band SAR images.The advantage of this method is that it does not depend on modulation transfer functions(MTFs),in order to measure ocean surface waves.This method can be used in monitoring ocean surface wave propagation through open water areas into ice-covered areas,especially the marginal ice zone(MIZ)in polar oceans.
