With the increasing interest in highly concentrated electrolyte systems,correct determination of the cation transference number is important.Pulsed-field gradient NMR technique,which measures self-diffusion coefficien...With the increasing interest in highly concentrated electrolyte systems,correct determination of the cation transference number is important.Pulsed-field gradient NMR technique,which measures self-diffusion coefficients,is often applied on liquid electrolytes because of the wide accessibility and simple sample preparation.However,since the assumptions of this technique,that is,complete salt dissociation,all ions participating in motion,and all of them moving independently,no longer hold true in concentrated solutions,the transference numbers,thus obtained are often over-estimated.In the present work,impedance spectroscopy at a frequency range of 1 MHz to 0.1 mHz was used to examine the concentration effect on lithium-ion transference number under anion-blocking conditions T abc Liþfor two electrolytes:lithium bis(fluorosulfonyl)imide(LiFSI)in sulfolane(SL)and lithium bis(trifluorosulfonyl)imide(LiTFSI)in tetraglyme(G4).The T abc Liþof the former was almost an order of magnitude higher than that of the latter.It also appeared to increase with increasing concentration while the latter followed an opposite trend.The faster Li^(+)transport in the SL system is attributed to the formation of a liquid structure consisting of extended chains/bridges of SL molecules and the anions,which facilitate a cation-hopping/ligand-exchanged-typed diffusion mechanism by partially decoupling the cations from the anions and solvent molecules.The G4 system,in contrast,is dominated by the formation of long-lived,stable[Li(G4)]+solvation cages that results in a sluggish Li+transport.The difference between the two transport mechanisms is discussed via comparison of the bulk ionic conductivity,viscosity,ion self-diffusion coefficients,and the Onsager transport coefficients.展开更多
Various features of the atmospheric environment affect the number of migratory insects, besides their initial population. However, little is known about the impact of atmospheric low-frequency oscillation(10 to 90 day...Various features of the atmospheric environment affect the number of migratory insects, besides their initial population. However, little is known about the impact of atmospheric low-frequency oscillation(10 to 90 days) on insect migration. A case study was conducted to ascertain the influence of low-frequency atmospheric oscillation on the immigration of brown planthopper, Nilaparvata lugens(Stl), in Hunan and Jiangxi provinces. The results showed the following:(1) The number of immigrating N. lugens from April to June of 2007 through 2016 mainly exhibited a periodic oscillation of 10 to 20 days.(2) The 10-20 d low-frequency number of immigrating N. lugens was significantly correlated with a low-frequency wind field and a geopotential height field at 850 h Pa.(3) During the peak phase of immigration, southwest or south winds served as a driving force and carried N. lugens populations northward, and when in the back of the trough and the front of the ridge, the downward airflow created a favorable condition for N. lugens to land in the study area. In conclusion, the northward migration of N. lugens was influenced by a low-frequency atmospheric circulation based on the analysis of dynamics. This study was the first research connecting atmospheric low-frequency oscillation to insect migration.展开更多
A lattice Boltzmann (LB) model with overall second-order accuracy is applied to the 1.5-layer shallow water equation for a wind-driven double-gyre ocean circulation. By introducing the second-order integral approximat...A lattice Boltzmann (LB) model with overall second-order accuracy is applied to the 1.5-layer shallow water equation for a wind-driven double-gyre ocean circulation. By introducing the second-order integral approximation for the collision operator, the model becomes fully explicit. In this case, any iterative technique is not needed. The Coriolis force and other external forces are included in the model with second-order accuracy, which is consistent with the discretized accuracy of the LB equation. The numerical results show correct physics of the ocean circulation driven by the double-gyre wind stress with different Reynolds numbers and different spatial resolutions. An intrinsic low-frequency variability of the shallow water model is also found. The wind-driven ocean circulation exhibits subannual and interannual oscillations, which are comparable to those of models in which the conventional numerical methods are used.展开更多
Low-frequency noise behavior in the MOSFETs processed in 65 run technology is investigated in this paper.Low-frequency noise for NMOS transistors agrees with McWhorter＇s theory（carrier number fluctuation）,low-frequ...Low-frequency noise behavior in the MOSFETs processed in 65 run technology is investigated in this paper.Low-frequency noise for NMOS transistors agrees with McWhorter＇s theory（carrier number fluctuation）,low-frequency noise in the sub-threshold regime agrees with McWhorter＇s theory for PMOS transistors while it agree with Hooge＇s theory（carrier mobility fluctuation） in the channel strong inversion regime.According to carrier number fluctuation model,the extracted trap densities near the interface between channel and gate oxide for NMOS and PMOS transistor are 3.94×10^（17） and 3.56×10^（18） cm^（-3）/eV respectively.According to carrier mobility fluctuation model,the extracted average Hooge＇s parameters are 2.42×10^（-5） and 4×10^（-4）.By consideration of BSIM compact model,it is shown that two noise parameters（NOIA and NOIB） can model the intrinsic channel noise.The extracted NOIA and NOIB are constants for PMOS and their values are equal to 3.94×10^（17） cm^（-3）/eV and 9.31×10^（-4） V^（-1）.But for NMOS,NOIA is also a constant while NOIB is inversely proportional to the effective gate voltage.The extracted NOIA and NOIB for NMOS are equal to 3.56×10^（18） cm^（-3）/eV and 1.53×10^（-2） V^（-1）.Good agreement between simulation and experimental results is achieved.展开更多
基金This work was supported by US Department of Army and the Joint Center for Energy Storage Research(JCESR),an Energy Innovation Hub funded by Depart-ment of Energy,Basic Energy Science,under an Interagency Agreement No.IAA SN202095.
文摘With the increasing interest in highly concentrated electrolyte systems,correct determination of the cation transference number is important.Pulsed-field gradient NMR technique,which measures self-diffusion coefficients,is often applied on liquid electrolytes because of the wide accessibility and simple sample preparation.However,since the assumptions of this technique,that is,complete salt dissociation,all ions participating in motion,and all of them moving independently,no longer hold true in concentrated solutions,the transference numbers,thus obtained are often over-estimated.In the present work,impedance spectroscopy at a frequency range of 1 MHz to 0.1 mHz was used to examine the concentration effect on lithium-ion transference number under anion-blocking conditions T abc Liþfor two electrolytes:lithium bis(fluorosulfonyl)imide(LiFSI)in sulfolane(SL)and lithium bis(trifluorosulfonyl)imide(LiTFSI)in tetraglyme(G4).The T abc Liþof the former was almost an order of magnitude higher than that of the latter.It also appeared to increase with increasing concentration while the latter followed an opposite trend.The faster Li^(+)transport in the SL system is attributed to the formation of a liquid structure consisting of extended chains/bridges of SL molecules and the anions,which facilitate a cation-hopping/ligand-exchanged-typed diffusion mechanism by partially decoupling the cations from the anions and solvent molecules.The G4 system,in contrast,is dominated by the formation of long-lived,stable[Li(G4)]+solvation cages that results in a sluggish Li+transport.The difference between the two transport mechanisms is discussed via comparison of the bulk ionic conductivity,viscosity,ion self-diffusion coefficients,and the Onsager transport coefficients.
基金National Science Foundation of China(41075086,41475106)Science Research Program of Universities and Colleges in Jiangsu Province(14KJA170003)Priority Academic Program Development of Jiangsu Higher Education Institutions(IRT1147)
文摘Various features of the atmospheric environment affect the number of migratory insects, besides their initial population. However, little is known about the impact of atmospheric low-frequency oscillation(10 to 90 days) on insect migration. A case study was conducted to ascertain the influence of low-frequency atmospheric oscillation on the immigration of brown planthopper, Nilaparvata lugens(Stl), in Hunan and Jiangxi provinces. The results showed the following:(1) The number of immigrating N. lugens from April to June of 2007 through 2016 mainly exhibited a periodic oscillation of 10 to 20 days.(2) The 10-20 d low-frequency number of immigrating N. lugens was significantly correlated with a low-frequency wind field and a geopotential height field at 850 h Pa.(3) During the peak phase of immigration, southwest or south winds served as a driving force and carried N. lugens populations northward, and when in the back of the trough and the front of the ridge, the downward airflow created a favorable condition for N. lugens to land in the study area. In conclusion, the northward migration of N. lugens was influenced by a low-frequency atmospheric circulation based on the analysis of dynamics. This study was the first research connecting atmospheric low-frequency oscillation to insect migration.
基金The work was supported by the One Hundred Talents Project of the Chinese Academy of Sciences(Grant No.KCL14014)the Impacts of Ocean-Land-Atmosphere Interactions over the East Asian Mon soon Region on the Climate in China(EAMOLA)(Grant No:ZKCX2-SW-210)the National Outstanding Youth Science Foundation of China(Grant No.40325016).
文摘A lattice Boltzmann (LB) model with overall second-order accuracy is applied to the 1.5-layer shallow water equation for a wind-driven double-gyre ocean circulation. By introducing the second-order integral approximation for the collision operator, the model becomes fully explicit. In this case, any iterative technique is not needed. The Coriolis force and other external forces are included in the model with second-order accuracy, which is consistent with the discretized accuracy of the LB equation. The numerical results show correct physics of the ocean circulation driven by the double-gyre wind stress with different Reynolds numbers and different spatial resolutions. An intrinsic low-frequency variability of the shallow water model is also found. The wind-driven ocean circulation exhibits subannual and interannual oscillations, which are comparable to those of models in which the conventional numerical methods are used.
基金supported by the National Natural Science Foundation of China(Nos.61574048,61204112)the Guangdong Natural Science Foundation(No.2014A030313656)
文摘Low-frequency noise behavior in the MOSFETs processed in 65 run technology is investigated in this paper.Low-frequency noise for NMOS transistors agrees with McWhorter＇s theory（carrier number fluctuation）,low-frequency noise in the sub-threshold regime agrees with McWhorter＇s theory for PMOS transistors while it agree with Hooge＇s theory（carrier mobility fluctuation） in the channel strong inversion regime.According to carrier number fluctuation model,the extracted trap densities near the interface between channel and gate oxide for NMOS and PMOS transistor are 3.94×10^（17） and 3.56×10^（18） cm^（-3）/eV respectively.According to carrier mobility fluctuation model,the extracted average Hooge＇s parameters are 2.42×10^（-5） and 4×10^（-4）.By consideration of BSIM compact model,it is shown that two noise parameters（NOIA and NOIB） can model the intrinsic channel noise.The extracted NOIA and NOIB are constants for PMOS and their values are equal to 3.94×10^（17） cm^（-3）/eV and 9.31×10^（-4） V^（-1）.But for NMOS,NOIA is also a constant while NOIB is inversely proportional to the effective gate voltage.The extracted NOIA and NOIB for NMOS are equal to 3.56×10^（18） cm^（-3）/eV and 1.53×10^（-2） V^（-1）.Good agreement between simulation and experimental results is achieved.
