With the continual deployment of power-electronics-interfaced renewable energy resources,increasing privacy concerns due to deregulation of electricity markets,and the diversification of demand-side activities,traditi...With the continual deployment of power-electronics-interfaced renewable energy resources,increasing privacy concerns due to deregulation of electricity markets,and the diversification of demand-side activities,traditional knowledge-based power system dynamic modeling methods are faced with unprecedented challenges.Data-driven modeling has been increasingly studied in recent years because of its lesser need for prior knowledge,higher capability of handling large-scale systems,and better adaptability to variations of system operating conditions.This paper discusses about the motivations and the generalized process of datadriven modeling,and provides a comprehensive overview of various state-of-the-art techniques and applications.It also comparatively presents the advantages and disadvantages of these methods and provides insight into outstanding challenges and possible research directions for the future.展开更多
Rutile germanium oxide(rutile GeO_(2)),a semiconductor,can act as a half-metallic compound and is a promising material for spintronic and optoelectronic applications.Calculations were performed using the Korringa–Koh...Rutile germanium oxide(rutile GeO_(2)),a semiconductor,can act as a half-metallic compound and is a promising material for spintronic and optoelectronic applications.Calculations were performed using the Korringa–Kohn–Rostoker(KKR)approach and the coherent potential approximation(CPA),which were further combined with two approximations,the local density approximation(LDA)and the self-interaction corrected LDA approximation(LDA-SIC),to study the electronic structure of bulk rutile GeO_(2) doped and co-doped with three transition-metal impurities:Fe,Co,and Ni.The doping value was set to 10%,while the co-doping level was set to 5%for each impurity.The main findings of this work are:(1)a direct ultrawide bandgap of4.80 eV is observed and the rutile GeO_(2) exhibits an N-type semiconducting property.(2)Doped and co-doped GeO_(2) acquire a magnetic behavior and exhibit half-metallicity.(3)The mechanism responsible for these properties is also studied.(4)The critical temperature can reach 334 K when GeO_(2) is doped with Fe,while it rises to 398 K when it is co-doped with Fe and Co.(5)The spin polarization can be improved by co-doping.It can be inferred that rutile GeO_(2) doped or codoped with(Co,Fe)transition metals can be considered to be potential candidates for spintronic and optoelectronic applications.展开更多
Improving the spatial and spectral resolution of 2D X-ray near-edge absorption structure(XANES)has been a decade-long pursuit to probe local chemical reactions at the nanoscale.However,the poor signal-to-noise ratio i...Improving the spatial and spectral resolution of 2D X-ray near-edge absorption structure(XANES)has been a decade-long pursuit to probe local chemical reactions at the nanoscale.However,the poor signal-to-noise ratio in the measured images poses significant challenges in quantitative analysis,especially when the element of interest is at a low concentration.In this work,we developed a postimaging processing method using deep neural network to reliably improve the signal-to-noise ratio in the XANES images.展开更多
In this paper, both the standard finite element discretization and a two-scale finite element discretization for SchrSdinger equations are studied. The numerical analysis is based on the regularity that is also obtain...In this paper, both the standard finite element discretization and a two-scale finite element discretization for SchrSdinger equations are studied. The numerical analysis is based on the regularity that is also obtained in this paper for the Schroedinger equations. Very satisfying applications to electronic structure computations are provided, too.展开更多
CONSPECTUS:The demand for lithium ion batteries continues to expand for powering applications such as portable electronics,grid-scale energy storage,and electric vehicles.As the application requirements advance,the in...CONSPECTUS:The demand for lithium ion batteries continues to expand for powering applications such as portable electronics,grid-scale energy storage,and electric vehicles.As the application requirements advance,the innovation of lithium ion batteries toward higher energy density and power output is required.Along with the investigation of new materials,an important strategy for increasing battery energy content is to design electrodes with high areal loading to minimize the fraction of nonactive materials such as current collectors,separators,and packaging components,resulting in significant gains in energy content and the reduction of the system-level cost.However,the adoption of thick high areal loading electrodes has been impeded by sluggish charge transport and mechanical instability.With conventional slurry cast electrodes,battery function significantly deteriorates with increases in electrode thickness due to high cell polarization and the incomplete utilization of active materials.Thus,a consideration of approaches that facilitate an understanding and eventual adoption of high-loading electrodes is warranted to enable the deliberate advancement of next-generation batteries.展开更多
In this work,we developed the CHARMM all-atom force field parameters for the nonstandard biological residue chalcone,followed by the standard protocol for the CHARMM27 force field development.Target data were generate...In this work,we developed the CHARMM all-atom force field parameters for the nonstandard biological residue chalcone,followed by the standard protocol for the CHARMM27 force field development.Target data were generated via ab initio calculations at the MP2/6-31G* and HF/6-31G* levels.The reference data included interaction energies between water and the model compound F(a fragment of chalcone).Bond,angle,and torsion parameters were derived from the ab initio calculations and renormalized to maintain compatibility with the existing CHARMM27 parameters of standard residues.The optimized CHARMM parameters perform well in reproducing the target data.We expect that the extension of the CHARMM27 force field parameters for chalcone will facilitate the molecular simulation studies of the reaction mechanism of intramolecular cyclization of chalcone catalyzed by chalcone isomerase.展开更多
We consider the blow-up behavior of Hammerstein-type delay Volterra integral equations （DVIEs）. Two types of delays, i.e., vanishing delay （pantograph delay） and non-vanishing delay （constant delay）, are conside...We consider the blow-up behavior of Hammerstein-type delay Volterra integral equations （DVIEs）. Two types of delays, i.e., vanishing delay （pantograph delay） and non-vanishing delay （constant delay）, are considered. With the same assumptions of Volterra integral equations （VIEs）, in a similar technology to VIEs, the blow-up conditions of the two types of DVIEs are given. The blow-up behaviors of DVIEs with non-vanishing delay vary with different initial functions and the length of the lag, while DVIEs with pantograph delay own the same blow-up behavior of VIEs. Some examples and applications to delay differential equations illustrate this influence.展开更多
For the past two decades,conversion and alloying-type materials have been heralded as the natural heir to commercially available graphite anodes due to their ability to deliver high gravimetric/volumetric power.Commer...For the past two decades,conversion and alloying-type materials have been heralded as the natural heir to commercially available graphite anodes due to their ability to deliver high gravimetric/volumetric power.Commercialization of batteries with these high-energy-density active materials could impact a variety of sectors including electric vehicles,grid storage,and consumer electronics and contribute toward an ever-increasing electrified world.However,the various failure mechanisms from inherent interfacial chemical instabilities associated with these materials make them unable to be merely substituted into currently available electrode fabrication and formulation processing techniques.As a result,realizing the high theoretical capacity and achieving commercial viability of these materials will rely on the careful manipulation of interfacial chemical interactions that dictate and control various kinetic and transport processes across multiple scales of the composite electrode.This has led to a plethora of research that has focused on systematically understanding properties of the different electrode components and designing carefully constructed electrode formulations to achieve composite electrodes with increased chemical stability,enhanced local mixed conductivities,or improved mechanical resilience.This Account relates recent progress in the understanding of synergetic opportunities for energy-dense,resilient composite anodes.By understanding the interplay between components of the composite electrode,we can construct enhanced well-integrated electrodes with performance metrics that surpass empirically derived architectures.Due to the increased complexity of high-volume-expanding electrodes,performance is more than the cumulative contributions of the individual components,and therefore energy and compatibility matching are important for robust electrochemical performance across cycling,rate capability,facile lithium-ion transport,and stability.In this Account,synergistic opportunities are framed from a chemistry perspective as we focus on examining interfacial interactions that span all electrode components:the active material surface,conductive agent linkage,and polymeric binder mesoscale.Control of key interfacial chemistry can be achieved through chemical functionalization,physical interactions,and other types of linkages and thereby lead to utilization of high-energy-density active materials in robust composite electrodes.Leveraging several techniques such as the Hanson solubility parameter(HSP)analysis,X-ray photoelectron spectroscopy(XPS),and Fourier transform infrared(FT-IR)spectroscopy among others can be important in gaining mechanistic insights for key kinetic and transport phenomena that occur across multiple interface length scales.Importantly,understanding the underlying effect of interfacial manipulation on the mechanisms of transport and kinetic processes leads to the development of experimental toolsets and design frameworks applicable to not just current material classes but to forward-looking chemistries that can be applied to next-generation battery materials.Herein,we discuss interfacial control of the composite electrodes via chemical modification techniques toward the creation of reliable,long-lasting,energy-dense lithium-ion batteries.展开更多
基金supported by the U.S.Department of Energy’s Office of Energy Efficiency and Renewable Energy(EERE)under the Solar Energy Technologies Office Award Number 38456.
文摘With the continual deployment of power-electronics-interfaced renewable energy resources,increasing privacy concerns due to deregulation of electricity markets,and the diversification of demand-side activities,traditional knowledge-based power system dynamic modeling methods are faced with unprecedented challenges.Data-driven modeling has been increasingly studied in recent years because of its lesser need for prior knowledge,higher capability of handling large-scale systems,and better adaptability to variations of system operating conditions.This paper discusses about the motivations and the generalized process of datadriven modeling,and provides a comprehensive overview of various state-of-the-art techniques and applications.It also comparatively presents the advantages and disadvantages of these methods and provides insight into outstanding challenges and possible research directions for the future.
文摘Rutile germanium oxide(rutile GeO_(2)),a semiconductor,can act as a half-metallic compound and is a promising material for spintronic and optoelectronic applications.Calculations were performed using the Korringa–Kohn–Rostoker(KKR)approach and the coherent potential approximation(CPA),which were further combined with two approximations,the local density approximation(LDA)and the self-interaction corrected LDA approximation(LDA-SIC),to study the electronic structure of bulk rutile GeO_(2) doped and co-doped with three transition-metal impurities:Fe,Co,and Ni.The doping value was set to 10%,while the co-doping level was set to 5%for each impurity.The main findings of this work are:(1)a direct ultrawide bandgap of4.80 eV is observed and the rutile GeO_(2) exhibits an N-type semiconducting property.(2)Doped and co-doped GeO_(2) acquire a magnetic behavior and exhibit half-metallicity.(3)The mechanism responsible for these properties is also studied.(4)The critical temperature can reach 334 K when GeO_(2) is doped with Fe,while it rises to 398 K when it is co-doped with Fe and Co.(5)The spin polarization can be improved by co-doping.It can be inferred that rutile GeO_(2) doped or codoped with(Co,Fe)transition metals can be considered to be potential candidates for spintronic and optoelectronic applications.
基金supported by the LDRD project 24255 received from Brookhaven National Laboratory.Z.LM.T.are supported by the Department of Energy,Basic Energy Sciences under project DE-SC0019111。
文摘Improving the spatial and spectral resolution of 2D X-ray near-edge absorption structure(XANES)has been a decade-long pursuit to probe local chemical reactions at the nanoscale.However,the poor signal-to-noise ratio in the measured images poses significant challenges in quantitative analysis,especially when the element of interest is at a low concentration.In this work,we developed a postimaging processing method using deep neural network to reliably improve the signal-to-noise ratio in the XANES images.
基金the National Science Founda-tion of China under grant 10425105the National Basic Research Program under grant 2005CB321704
文摘In this paper, both the standard finite element discretization and a two-scale finite element discretization for SchrSdinger equations are studied. The numerical analysis is based on the regularity that is also obtained in this paper for the Schroedinger equations. Very satisfying applications to electronic structure computations are provided, too.
基金The preparation of this manuscript was supported as part of the Center for Mesoscale Transport Properties,funded by the U.S.Department of Energy,Office of Science,Basic Energy Sciences,under award no.DE-SC0012673E.S.T.acknowledges support from the William and Jane Knapp Chair in Energy and the Environment。
文摘CONSPECTUS:The demand for lithium ion batteries continues to expand for powering applications such as portable electronics,grid-scale energy storage,and electric vehicles.As the application requirements advance,the innovation of lithium ion batteries toward higher energy density and power output is required.Along with the investigation of new materials,an important strategy for increasing battery energy content is to design electrodes with high areal loading to minimize the fraction of nonactive materials such as current collectors,separators,and packaging components,resulting in significant gains in energy content and the reduction of the system-level cost.However,the adoption of thick high areal loading electrodes has been impeded by sluggish charge transport and mechanical instability.With conventional slurry cast electrodes,battery function significantly deteriorates with increases in electrode thickness due to high cell polarization and the incomplete utilization of active materials.Thus,a consideration of approaches that facilitate an understanding and eventual adoption of high-loading electrodes is warranted to enable the deliberate advancement of next-generation batteries.
基金National Institute of Biological Science, Beijing 102206,Chinasupported by the Major State Basic Research Development Programs of China(2011CBA00701)+3 种基金the National Natural Science Foundation of China(20973077,20973049)the Doctoral Fund of Ministry of Education of China(20112303110005)the Foundation for the Department of Education of Heilongjiang Province (1152G010,11551077)the Science Foundation for Leading Experts in Academe of Harbin of China(2011RFJGS026)
文摘In this work,we developed the CHARMM all-atom force field parameters for the nonstandard biological residue chalcone,followed by the standard protocol for the CHARMM27 force field development.Target data were generated via ab initio calculations at the MP2/6-31G* and HF/6-31G* levels.The reference data included interaction energies between water and the model compound F(a fragment of chalcone).Bond,angle,and torsion parameters were derived from the ab initio calculations and renormalized to maintain compatibility with the existing CHARMM27 parameters of standard residues.The optimized CHARMM parameters perform well in reproducing the target data.We expect that the extension of the CHARMM27 force field parameters for chalcone will facilitate the molecular simulation studies of the reaction mechanism of intramolecular cyclization of chalcone catalyzed by chalcone isomerase.
基金Acknowledgements The authors thank the anonymous referees for the constructive criticism and the many valuable suggestions that led to a significant improvement in the presentation of the main results. This work was supported by the National Natural Science Foundation of China （Grant No. 11071050）, the Fundamental Research Funds for the Central Universities （Grant No. HIT.NSRIF.2010051）, the Hong Kong Research Grants Council （RGC Project No. 200210）, and the Natural Sciences and Engineering Research Council of Canada （NSERC Discovery Grant A9406）.
文摘We consider the blow-up behavior of Hammerstein-type delay Volterra integral equations （DVIEs）. Two types of delays, i.e., vanishing delay （pantograph delay） and non-vanishing delay （constant delay）, are considered. With the same assumptions of Volterra integral equations （VIEs）, in a similar technology to VIEs, the blow-up conditions of the two types of DVIEs are given. The blow-up behaviors of DVIEs with non-vanishing delay vary with different initial functions and the length of the lag, while DVIEs with pantograph delay own the same blow-up behavior of VIEs. Some examples and applications to delay differential equations illustrate this influence.
基金This work was performed as part of the Center for Mesoscale Transport Properties,an Energy Frontier Research Center supported by the U.S.Department of Energy,Office of Science,Basic Energy Sciences,under award#DE-SC0012673.E.R.also appreciates support from Lehigh University through funds associated with the Carl Robert Anderson Chair in Chemical Engineering.E.S.T.acknowledges support as the William and Jane Knapp Chair for Energy and the Environment at Stony Brook University。
文摘For the past two decades,conversion and alloying-type materials have been heralded as the natural heir to commercially available graphite anodes due to their ability to deliver high gravimetric/volumetric power.Commercialization of batteries with these high-energy-density active materials could impact a variety of sectors including electric vehicles,grid storage,and consumer electronics and contribute toward an ever-increasing electrified world.However,the various failure mechanisms from inherent interfacial chemical instabilities associated with these materials make them unable to be merely substituted into currently available electrode fabrication and formulation processing techniques.As a result,realizing the high theoretical capacity and achieving commercial viability of these materials will rely on the careful manipulation of interfacial chemical interactions that dictate and control various kinetic and transport processes across multiple scales of the composite electrode.This has led to a plethora of research that has focused on systematically understanding properties of the different electrode components and designing carefully constructed electrode formulations to achieve composite electrodes with increased chemical stability,enhanced local mixed conductivities,or improved mechanical resilience.This Account relates recent progress in the understanding of synergetic opportunities for energy-dense,resilient composite anodes.By understanding the interplay between components of the composite electrode,we can construct enhanced well-integrated electrodes with performance metrics that surpass empirically derived architectures.Due to the increased complexity of high-volume-expanding electrodes,performance is more than the cumulative contributions of the individual components,and therefore energy and compatibility matching are important for robust electrochemical performance across cycling,rate capability,facile lithium-ion transport,and stability.In this Account,synergistic opportunities are framed from a chemistry perspective as we focus on examining interfacial interactions that span all electrode components:the active material surface,conductive agent linkage,and polymeric binder mesoscale.Control of key interfacial chemistry can be achieved through chemical functionalization,physical interactions,and other types of linkages and thereby lead to utilization of high-energy-density active materials in robust composite electrodes.Leveraging several techniques such as the Hanson solubility parameter(HSP)analysis,X-ray photoelectron spectroscopy(XPS),and Fourier transform infrared(FT-IR)spectroscopy among others can be important in gaining mechanistic insights for key kinetic and transport phenomena that occur across multiple interface length scales.Importantly,understanding the underlying effect of interfacial manipulation on the mechanisms of transport and kinetic processes leads to the development of experimental toolsets and design frameworks applicable to not just current material classes but to forward-looking chemistries that can be applied to next-generation battery materials.Herein,we discuss interfacial control of the composite electrodes via chemical modification techniques toward the creation of reliable,long-lasting,energy-dense lithium-ion batteries.
