The dual-metal-atom catalysts(DACs)have aroused much attention as they possess the advantages of single-atom and metal alloy catalysts.And the DACs have exhibited enhanced performance in various electrocatalytic react...The dual-metal-atom catalysts(DACs)have aroused much attention as they possess the advantages of single-atom and metal alloy catalysts.And the DACs have exhibited enhanced performance in various electrocatalytic reactions,such as hydrogen/oxygen evolution and oxygen/carbon dioxide/nitrogen reduction.In this review,we mainly overview the latest understanding of the advantages of DACs for these reactions.This review will start with the familiar characterization methods for DACs,then the primary synthesis strategies for DACs will be discussed.Emphasis is given to the advantages of DACs in catalytic reactions,including the adsorption and activation,electronic structure regulation,breaking scaling relations,reducing energy barriers,cascading and coupling,synergy effect,and providing mechanism research platforms.Finally,personal perspectives and challenges for the further development of DACs are briefly discussed.展开更多
Some people try to construct an orthonormal wavelet such that the corresponding scaling function（t）has the cardinal property,i.e.（n）=δ<sub>n0</sub>,since such wavelets have many good applications.Unfo...Some people try to construct an orthonormal wavelet such that the corresponding scaling function（t）has the cardinal property,i.e.（n）=δ<sub>n0</sub>,since such wavelets have many good applications.Unfortunate]y it is impossible to do so,except for a trivial case.In this work,a family of non-orthogonal cardinal wavelets with compact support is constructed and their duals are investigated.展开更多
The optimality criteria （OC） method and mathematical programming （MP） were combined to found the sectional optimization model of frame structures. Different methods were adopted to deal with the different constrai...The optimality criteria （OC） method and mathematical programming （MP） were combined to found the sectional optimization model of frame structures. Different methods were adopted to deal with the different constraints. The stress constraints as local constraints were approached by zero-order approximation and transformed into movable sectional lower limits with the full stress criterion. The displacement constraints as global constraints were transformed into explicit expressions with the unit virtual load method. Thus an approximate explicit model for the sectional optimization of frame structures was built with stress and displacement constraints. To improve the resolution efficiency, the dual-quadratic programming was adopted to transform the original optimization model into a dual problem according to the dual theory and solved iteratively in its dual space. A method called approximate scaling step was adopted to reduce computations and smooth the iterative process. Negative constraints were deleted to reduce the size of the optimization model. With MSC/Nastran software as structural solver and MSC/Patran software as developing platform, the sectional optimization software of frame structures was accomplished, considering stress and displacement constraints. The examples show that the efficiency and accuracy are improved.展开更多
The power systems economic and safety operation considering large-scale wind power penetration are now facing great challenges, which are based on reliable power supply and predictable load demands in the past. A roll...The power systems economic and safety operation considering large-scale wind power penetration are now facing great challenges, which are based on reliable power supply and predictable load demands in the past. A rolling generation dispatch model based on ultra-short-term wind power forecast was proposed. In generation dispatch process, the model rolling correct not only the conventional units power output but also the power from wind farm, simultaneously. Second order Markov chain model was utilized to modify wind power prediction error state (WPPES) and update forecast results of wind power over the remaining dispatch periods. The prime-dual affine scaling interior point method was used to solve the proposed model that taken into account the constraints of multi-periods power balance, unit output adjustment, up spinning reserve and down spinning reserve.展开更多
基金the financial support from the Natural Science Foundation of Shandong Province(Nos.ZR2021QE096,ZR2021MB101,ZR2021ME113 and ZR2021ME177)。
文摘The dual-metal-atom catalysts(DACs)have aroused much attention as they possess the advantages of single-atom and metal alloy catalysts.And the DACs have exhibited enhanced performance in various electrocatalytic reactions,such as hydrogen/oxygen evolution and oxygen/carbon dioxide/nitrogen reduction.In this review,we mainly overview the latest understanding of the advantages of DACs for these reactions.This review will start with the familiar characterization methods for DACs,then the primary synthesis strategies for DACs will be discussed.Emphasis is given to the advantages of DACs in catalytic reactions,including the adsorption and activation,electronic structure regulation,breaking scaling relations,reducing energy barriers,cascading and coupling,synergy effect,and providing mechanism research platforms.Finally,personal perspectives and challenges for the further development of DACs are briefly discussed.
基金This work is supported by the project of new stars of Beijing
文摘Some people try to construct an orthonormal wavelet such that the corresponding scaling function（t）has the cardinal property,i.e.（n）=δ<sub>n0</sub>,since such wavelets have many good applications.Unfortunate]y it is impossible to do so,except for a trivial case.In this work,a family of non-orthogonal cardinal wavelets with compact support is constructed and their duals are investigated.
基金Project supported by the National Natural Science Foundation of China(No. 10472003) the Natural Science Foundation of Beijing(No.3002002) the Science Foundation of Beijing Municipal Commission of Education(No.KM200410005019)
文摘The optimality criteria （OC） method and mathematical programming （MP） were combined to found the sectional optimization model of frame structures. Different methods were adopted to deal with the different constraints. The stress constraints as local constraints were approached by zero-order approximation and transformed into movable sectional lower limits with the full stress criterion. The displacement constraints as global constraints were transformed into explicit expressions with the unit virtual load method. Thus an approximate explicit model for the sectional optimization of frame structures was built with stress and displacement constraints. To improve the resolution efficiency, the dual-quadratic programming was adopted to transform the original optimization model into a dual problem according to the dual theory and solved iteratively in its dual space. A method called approximate scaling step was adopted to reduce computations and smooth the iterative process. Negative constraints were deleted to reduce the size of the optimization model. With MSC/Nastran software as structural solver and MSC/Patran software as developing platform, the sectional optimization software of frame structures was accomplished, considering stress and displacement constraints. The examples show that the efficiency and accuracy are improved.
文摘The power systems economic and safety operation considering large-scale wind power penetration are now facing great challenges, which are based on reliable power supply and predictable load demands in the past. A rolling generation dispatch model based on ultra-short-term wind power forecast was proposed. In generation dispatch process, the model rolling correct not only the conventional units power output but also the power from wind farm, simultaneously. Second order Markov chain model was utilized to modify wind power prediction error state (WPPES) and update forecast results of wind power over the remaining dispatch periods. The prime-dual affine scaling interior point method was used to solve the proposed model that taken into account the constraints of multi-periods power balance, unit output adjustment, up spinning reserve and down spinning reserve.
