Since the D-band center theory was proposed,it has been widely used in the fields of surface chemistry by almost all researchers,due to its easy understanding,convenient operation and relative accuracy.However,with th...Since the D-band center theory was proposed,it has been widely used in the fields of surface chemistry by almost all researchers,due to its easy understanding,convenient operation and relative accuracy.However,with the continuous development of material systems and modification strategies,researchers have gradually found that D-band center theory is usually effective for large metal particle systems,but for small metal particle systems or semiconductors,such as single atom systems,the opposite conclusion to the D-band center theory is often obtained.To solve the issue above,here we propose a bonding and anti-bonding orbitals stable electron intensity difference(BASED)theory for surface chemistry.The newly-proposed BASED theory can not only successfully explain the abnormal phenomena of D-band center theory,but also exhibits a higher accuracy for prediction of adsorption energy and bond length of intermediates on active sites.Importantly,a new phenomenon of the spin transition state in the adsorption process is observed based on the BASED theory,where the active center atom usually yields an unstable high spin transition state to enhance its adsorption capability in the adsorption process of intermediates when their distance is about 2.5Å.In short,the BASED theory can be considered as a general principle to understand catalytic mechanism of intermediates on surfaces.展开更多
CuIn（S,Se）2 thin films were prepared by thermal crystallization of co-sputtered Cu-In alloy precursors in S/Se atmosphere. In-depth compositional uniformity is an important prereq- uisite for obtaining device-qualit...CuIn（S,Se）2 thin films were prepared by thermal crystallization of co-sputtered Cu-In alloy precursors in S/Se atmosphere. In-depth compositional uniformity is an important prereq- uisite for obtaining device-quality CuIn（S,Se）2 absorber thin films. In order to figure out the influence of heat treatments on in-depth composition uniformity of CuIn（S,Se）2 thin films, two kinds of reaction temperature profiles were investigated. One process is ＂one step profile＂, referring to formation of CuIn（S,Se）2 thin films just at elevated temperature （e.g. 500 ℃）. The other is ＂two step profile＂, which allows for slow diffusion of S and Se elements into the alloy precursors at a low temperature before the formation and re-crystallization of CuIn（S,Se）2 thin films at higher temperature （e.g. first 250 ℃ then 500 ℃）. X-ray diffrac- tion studies reveal that there is a discrepancy in the shape of （112） peak. Samples annealed with ＂one step profile＂ have splits on （112） peaks, while samples annealed with ＂two step profile＂ have relatively symmetrical （112） peaks. Grazing incident X-ray diffraction and en- ergy dispersive spectrum measurements of samples successively etched in bromine methanol show that CuIn（S,Se）2 thin films have better in-depth composition uniformity after ＂two step profile＂ annealing. The reaction mechanism during the two thermal processing was also investigated by X-ray diffraction and Raman spectra.展开更多
A coupled system of the interdecadal sea-air oscillator model is studied. The E1 Nifio-southem oscillation （ENSO） atmospheric physics oscillation is an abnormal phenomenon involved in the tropical Pacific ocean-atmo...A coupled system of the interdecadal sea-air oscillator model is studied. The E1 Nifio-southem oscillation （ENSO） atmospheric physics oscillation is an abnormal phenomenon involved in the tropical Pacific ocean-atmosphere interactions. The oscillator model is involved with the variations of both the eastern and western Pacific anomaly pat- terns. This paper proposes an ENSO atmospheric physics model using a method of the perturbation theory. The aim is to create an asymptotic solving method for the ENSO model. Employing the perturbed method, the asymptotic solution of corresponding problem is obtained, and the asymptotic behaviour of the solution is studied. Thus we can obtain the prognoses of the sea surface temperature anomaly and related physical quantities.展开更多
Based on traditional twin-roll casting process,Invar/Cu clad strips were successfully fabricated by using solid Invar alloy strip and molten Cu under conditions of high temperature,high pressure and plastic deformatio...Based on traditional twin-roll casting process,Invar/Cu clad strips were successfully fabricated by using solid Invar alloy strip and molten Cu under conditions of high temperature,high pressure and plastic deformation.A series of tests including tensile test,bending test,T-type peeling test and scanning electron microscope(SEM)and energy dispersive spectrometer(EDS)measurements were carried out to analyze the mechanical properties of Invar/Cu clad strips and the micro-morphology of tensile fracture surfaces and bonding interfaces.The results indicate that no delamination phenomenon occurs during the compatible deformation of Invar/Cu in bending test and only one stress platform exists in the tensile stress-strain curve when the bonding strength is large.On the contrary,different mechanical properties of Invar and Cu lead to delamination phenomenon during the uniaxial tensile test,which determines that two stress platforms occur on the stress-strain curve of Invar/Cu clad strips when two elements experience necking.The average peeling strength can be increased from13.85to42.31N/mm after heat treatment at800℃for1h,and the observation of the Cu side at peeling interface shows that more Fe is adhered on the Cu side after the heat treatment.All above illustrate that heat treatment can improve the strength of the bonding interface of Invar/Cu clad strips.展开更多
Validated satellite-derived sea surface temperatures (SSTs) are widely used for climate monitoring and ocean data assimilation systems. In this study, the Fengyun-3A (FY-3A) SST experimental product is evaluated using...Validated satellite-derived sea surface temperatures (SSTs) are widely used for climate monitoring and ocean data assimilation systems. In this study, the Fengyun-3A (FY-3A) SST experimental product is evaluated using Advanced Very High Resolution Radiometer (AVHRR)-merged and in situ SSTs. A comparison of AVHRR-merged SSTs reveals a negative bias of more than 2K in FY-3A SSTs in most of the tropical Pacific and low-latitude Indian and Atlantic Oceans. The error variance of FY-3A SSTs is estimated using three-way error analysis. FY-3A SSTs show regional error variance in global oceans with a maximum error variance of 2.2 K in the Pacific Ocean. In addition, a significant seasonal variation of error variance is present in FY-3A SSTs, which indicates that the quality of FY-3A SST could be improved by adjusting the parameters in the SST retrieval algorithm and by applying regional and seasonal algorithms, particularly in key areas such as the tropical Pacific Ocean. An objective analysis method is used to merge FY-3A SSTs with the drifter buoy data. The errors of FY-3A SSTs are decreased to-0.45K comparing with SST observations from GTSPP.展开更多
文摘Since the D-band center theory was proposed,it has been widely used in the fields of surface chemistry by almost all researchers,due to its easy understanding,convenient operation and relative accuracy.However,with the continuous development of material systems and modification strategies,researchers have gradually found that D-band center theory is usually effective for large metal particle systems,but for small metal particle systems or semiconductors,such as single atom systems,the opposite conclusion to the D-band center theory is often obtained.To solve the issue above,here we propose a bonding and anti-bonding orbitals stable electron intensity difference(BASED)theory for surface chemistry.The newly-proposed BASED theory can not only successfully explain the abnormal phenomena of D-band center theory,but also exhibits a higher accuracy for prediction of adsorption energy and bond length of intermediates on active sites.Importantly,a new phenomenon of the spin transition state in the adsorption process is observed based on the BASED theory,where the active center atom usually yields an unstable high spin transition state to enhance its adsorption capability in the adsorption process of intermediates when their distance is about 2.5Å.In short,the BASED theory can be considered as a general principle to understand catalytic mechanism of intermediates on surfaces.
文摘CuIn（S,Se）2 thin films were prepared by thermal crystallization of co-sputtered Cu-In alloy precursors in S/Se atmosphere. In-depth compositional uniformity is an important prereq- uisite for obtaining device-quality CuIn（S,Se）2 absorber thin films. In order to figure out the influence of heat treatments on in-depth composition uniformity of CuIn（S,Se）2 thin films, two kinds of reaction temperature profiles were investigated. One process is ＂one step profile＂, referring to formation of CuIn（S,Se）2 thin films just at elevated temperature （e.g. 500 ℃）. The other is ＂two step profile＂, which allows for slow diffusion of S and Se elements into the alloy precursors at a low temperature before the formation and re-crystallization of CuIn（S,Se）2 thin films at higher temperature （e.g. first 250 ℃ then 500 ℃）. X-ray diffrac- tion studies reveal that there is a discrepancy in the shape of （112） peak. Samples annealed with ＂one step profile＂ have splits on （112） peaks, while samples annealed with ＂two step profile＂ have relatively symmetrical （112） peaks. Grazing incident X-ray diffraction and en- ergy dispersive spectrum measurements of samples successively etched in bromine methanol show that CuIn（S,Se）2 thin films have better in-depth composition uniformity after ＂two step profile＂ annealing. The reaction mechanism during the two thermal processing was also investigated by X-ray diffraction and Raman spectra.
基金Under the auspices of National Natural Science Foundation of China (No.40876010)Key Direction in Knowledge Innovation Programs of Chinese Academy of Sciences (No. KZCX2-YW-Q03-08)+2 种基金Research and Development Special Fund for Public Welfare Industry (Meteorology) (No. GYHY200806010)LASG State Key Laboratory Special Fund, Foundation of E-Institutes of Shanghai Municipal Education Commission (No.E03004)Natural Science Foundation of Education Department of Fujian Province (No.JA10288)
文摘A coupled system of the interdecadal sea-air oscillator model is studied. The E1 Nifio-southem oscillation （ENSO） atmospheric physics oscillation is an abnormal phenomenon involved in the tropical Pacific ocean-atmosphere interactions. The oscillator model is involved with the variations of both the eastern and western Pacific anomaly pat- terns. This paper proposes an ENSO atmospheric physics model using a method of the perturbation theory. The aim is to create an asymptotic solving method for the ENSO model. Employing the perturbed method, the asymptotic solution of corresponding problem is obtained, and the asymptotic behaviour of the solution is studied. Thus we can obtain the prognoses of the sea surface temperature anomaly and related physical quantities.
基金Project (51474189) supported by the National Natural Science Foundation of ChinaProject (E2018203446) supported by the Excellent Youth Foundation of Hebei Scientific Committee,ChinaProject (QN2015214) supported by the Educational Commission of Hebei Province,China
文摘Based on traditional twin-roll casting process,Invar/Cu clad strips were successfully fabricated by using solid Invar alloy strip and molten Cu under conditions of high temperature,high pressure and plastic deformation.A series of tests including tensile test,bending test,T-type peeling test and scanning electron microscope(SEM)and energy dispersive spectrometer(EDS)measurements were carried out to analyze the mechanical properties of Invar/Cu clad strips and the micro-morphology of tensile fracture surfaces and bonding interfaces.The results indicate that no delamination phenomenon occurs during the compatible deformation of Invar/Cu in bending test and only one stress platform exists in the tensile stress-strain curve when the bonding strength is large.On the contrary,different mechanical properties of Invar and Cu lead to delamination phenomenon during the uniaxial tensile test,which determines that two stress platforms occur on the stress-strain curve of Invar/Cu clad strips when two elements experience necking.The average peeling strength can be increased from13.85to42.31N/mm after heat treatment at800℃for1h,and the observation of the Cu side at peeling interface shows that more Fe is adhered on the Cu side after the heat treatment.All above illustrate that heat treatment can improve the strength of the bonding interface of Invar/Cu clad strips.
基金supported by the National Basic Research Program of China(973 Program,Grant Nos.2010CB951902 and 2011CB403505)the National Key Technologies R&D Program of China(Grant No.2009BAC51B03)the National Natural Science Foundation of China(Grant No.41106003)
文摘Validated satellite-derived sea surface temperatures (SSTs) are widely used for climate monitoring and ocean data assimilation systems. In this study, the Fengyun-3A (FY-3A) SST experimental product is evaluated using Advanced Very High Resolution Radiometer (AVHRR)-merged and in situ SSTs. A comparison of AVHRR-merged SSTs reveals a negative bias of more than 2K in FY-3A SSTs in most of the tropical Pacific and low-latitude Indian and Atlantic Oceans. The error variance of FY-3A SSTs is estimated using three-way error analysis. FY-3A SSTs show regional error variance in global oceans with a maximum error variance of 2.2 K in the Pacific Ocean. In addition, a significant seasonal variation of error variance is present in FY-3A SSTs, which indicates that the quality of FY-3A SST could be improved by adjusting the parameters in the SST retrieval algorithm and by applying regional and seasonal algorithms, particularly in key areas such as the tropical Pacific Ocean. An objective analysis method is used to merge FY-3A SSTs with the drifter buoy data. The errors of FY-3A SSTs are decreased to-0.45K comparing with SST observations from GTSPP.
