Epoxy asphalt concrete has been one of the mainstream technology of steel deck pavement in China. But little specification about evaluation system for its distress condition has been researched and maintenance was sti...Epoxy asphalt concrete has been one of the mainstream technology of steel deck pavement in China. But little specification about evaluation system for its distress condition has been researched and maintenance was still unsystematic. The section weight coefficient of different distress is proposed by analyzing the applicability of the “Highway Performance Assessment Standards”. Indexes mainly including SDPCI PDR and PCR are presented to evaluate its distress condition. The evaluation system and maintenance plan decision tree were recommended which can assist scientific maintenance of epoxy asphalt steel deck pavement.展开更多
In this paper,we studied the approximate sampleddata observer design for a class of stochastic nonlinear systems.Euler-Maruyama approximation was investigated in this paper because it is the basis of other higher prec...In this paper,we studied the approximate sampleddata observer design for a class of stochastic nonlinear systems.Euler-Maruyama approximation was investigated in this paper because it is the basis of other higher precision numerical methods,and it preserves important structures of the nonlinear systems.Also,the form of Euler-Maruyama model is simple and easy to be calculated.The results provide a reference for sampled-data observer design method for such stochastic nonlinear systems,and may be useful to many practical control applications,such as tracking control in mechanical systems.And the effectiveness of the approach is demonstrated by a simulation example.展开更多
Surface charge localization and inferior charge transfer efficiency seriously restrict the supply of reactive hydrogen and the reaction dynamics of CO_(2) photoreduction performance of photocatalysts.Herein,chemically...Surface charge localization and inferior charge transfer efficiency seriously restrict the supply of reactive hydrogen and the reaction dynamics of CO_(2) photoreduction performance of photocatalysts.Herein,chemically bonded BiVO_(4)/Bi_(19)Cl_(3)S_(27)(BVO/BCS)S-scheme heterojunction with a strong internal electric field is designed.Experimental and density function theory calculation results confirm that the elaborated heterojunction accelerates the vectorial migration of photogenerated charges from BiVO_(4) to Bi_(19)Cl_(3)S_(27) via the interfacial chemical bonding interactions(i.e.,Bi-O and Bi-S bonds)between Bi atoms of BVO and S atoms of BCS or Bi atoms of BCS and O atoms of BVO under light irradiation,breaking the interfacial barrier and surface charge localization of Bi_(19)Cl_(3)S_(27),and further decreasing the energy of reactive hydrogen generation,CO_(2) absorption and activation.The separation efficiency of photogenerated carriers is much more efficient than that counterpart individual in BVO/BCS S-scheme heterojunction system.As a result,BVO/BCS heterojunction exhibits a significantly improved continuous photocatalytic performance for CO_(2) reduction and the 24 h CO yield reaches 678.27μmol⋅g^(-1).This work provides an atomic-level insight into charge transfer kinetics and CO_(2) reduction mechanism in S-scheme heterojunction.展开更多
Equivalent models are essential for time-domain simulation and harmonic stability evaluation of renewable power plants.Such harmonic instability may co-occur at the plant-level and unit-level,or it may only occur at t...Equivalent models are essential for time-domain simulation and harmonic stability evaluation of renewable power plants.Such harmonic instability may co-occur at the plant-level and unit-level,or it may only occur at the unit-level,manifesting as local resonances.However,conventional equivalent methods can only simulate plant-level instability,but cannot consider such unit-level instability.To address this problem,the main contributions of this paper are as follows:1)Based on the impedance matrix and the eigenvalue analysis,the reason why conventional equivalent methods cannot accurately simulate unitlevel stability is studied.2)A double-machine equivalent method is proposed.The model used in this method is a minimumscale equivalent model capable of simulating plant-level and unit-level stability,simultaneously.It uses two single-machine models to represent a generation cluster containing N generation units.A single-machine model M_(1) represents N—1 generation units for simplification,while another single-machine model M_(2) represents the remaining one generation unit for simulating unitlevel stability.3)Furthermore,a practical improvement approach of the double-machine equivalent method is proposed for taking into account operating point differences and complex connection conditions.Finally,the proposed method is verified by simulations and experiments.展开更多
The integration of photovoltaic (PV) systems into weak-grid environments presents unique challenges to the stability of grid-connected inverters. This review provides a comprehensive overview of the research efforts f...The integration of photovoltaic (PV) systems into weak-grid environments presents unique challenges to the stability of grid-connected inverters. This review provides a comprehensive overview of the research efforts focused on investigating the stability of PV grid-connected inverters that operate under weak grid conditions. Weak grids are characterized by a low short-circuit capacity and low inertia, making it essential to explore strategies that enhance the stability and performance of inverters in such challenging environments. This review covers various aspects, including control strategies and advanced technologies implemented to address stability problems. The research findings related to the impact of weak grid conditions on PV inverters, modeling techniques, and analysis results are discussed. Additionally, this review highlights emerging trends, identifies gaps in the current research, and suggests potential avenues for future investigations aimed at improving the stability of PV grid-connected inverters in weak grid scenarios.展开更多
基金Sponsored by the Major Science and Technology Special Traffic and Transportation in Jiangsu Province(Grant No.2014Y02)the Jiangsu Natural Science Foundation(Grant Nos.BK20180113 and BK20181112)
文摘Epoxy asphalt concrete has been one of the mainstream technology of steel deck pavement in China. But little specification about evaluation system for its distress condition has been researched and maintenance was still unsystematic. The section weight coefficient of different distress is proposed by analyzing the applicability of the “Highway Performance Assessment Standards”. Indexes mainly including SDPCI PDR and PCR are presented to evaluate its distress condition. The evaluation system and maintenance plan decision tree were recommended which can assist scientific maintenance of epoxy asphalt steel deck pavement.
基金supported by the National High Technology Research and Development Program of China(863 Program)(2014AA06A503)the National Natural Science Foundation of China(61422307,61673361)+3 种基金the Scientific Research Starting Foundation for the Returned Overseas Chinese Scholars and Ministry of Education of Chinasupports from the Youth Top-notch Talent Support Programthe 1000-talent Youth Programthe Youth Yangtze River Scholarship
文摘In this paper,we studied the approximate sampleddata observer design for a class of stochastic nonlinear systems.Euler-Maruyama approximation was investigated in this paper because it is the basis of other higher precision numerical methods,and it preserves important structures of the nonlinear systems.Also,the form of Euler-Maruyama model is simple and easy to be calculated.The results provide a reference for sampled-data observer design method for such stochastic nonlinear systems,and may be useful to many practical control applications,such as tracking control in mechanical systems.And the effectiveness of the approach is demonstrated by a simulation example.
基金financially supported by Outstanding Talent Research Fund of Zhengzhou University,China Postdoc toral Science Foundation(2020TQ0277,2020M682328)Central Plains Science and Technology Innovation Leader Project(214200510006)+1 种基金China Scholarship Council(No.202108410356)Postdoctoral Science Foundation of Henan province(202002010).
文摘Surface charge localization and inferior charge transfer efficiency seriously restrict the supply of reactive hydrogen and the reaction dynamics of CO_(2) photoreduction performance of photocatalysts.Herein,chemically bonded BiVO_(4)/Bi_(19)Cl_(3)S_(27)(BVO/BCS)S-scheme heterojunction with a strong internal electric field is designed.Experimental and density function theory calculation results confirm that the elaborated heterojunction accelerates the vectorial migration of photogenerated charges from BiVO_(4) to Bi_(19)Cl_(3)S_(27) via the interfacial chemical bonding interactions(i.e.,Bi-O and Bi-S bonds)between Bi atoms of BVO and S atoms of BCS or Bi atoms of BCS and O atoms of BVO under light irradiation,breaking the interfacial barrier and surface charge localization of Bi_(19)Cl_(3)S_(27),and further decreasing the energy of reactive hydrogen generation,CO_(2) absorption and activation.The separation efficiency of photogenerated carriers is much more efficient than that counterpart individual in BVO/BCS S-scheme heterojunction system.As a result,BVO/BCS heterojunction exhibits a significantly improved continuous photocatalytic performance for CO_(2) reduction and the 24 h CO yield reaches 678.27μmol⋅g^(-1).This work provides an atomic-level insight into charge transfer kinetics and CO_(2) reduction mechanism in S-scheme heterojunction.
基金supported by the Joint Funds of the National Natural Science Foundation of China(U23A20655)the Science and Technology Tackling Plan Project of Anhui Province(202423h08050008)the Science and Technology Project of State Grid Anhui Electric Power Co.,Ltd.(SGAHDK00CNJS2500397).
文摘Equivalent models are essential for time-domain simulation and harmonic stability evaluation of renewable power plants.Such harmonic instability may co-occur at the plant-level and unit-level,or it may only occur at the unit-level,manifesting as local resonances.However,conventional equivalent methods can only simulate plant-level instability,but cannot consider such unit-level instability.To address this problem,the main contributions of this paper are as follows:1)Based on the impedance matrix and the eigenvalue analysis,the reason why conventional equivalent methods cannot accurately simulate unitlevel stability is studied.2)A double-machine equivalent method is proposed.The model used in this method is a minimumscale equivalent model capable of simulating plant-level and unit-level stability,simultaneously.It uses two single-machine models to represent a generation cluster containing N generation units.A single-machine model M_(1) represents N—1 generation units for simplification,while another single-machine model M_(2) represents the remaining one generation unit for simulating unitlevel stability.3)Furthermore,a practical improvement approach of the double-machine equivalent method is proposed for taking into account operating point differences and complex connection conditions.Finally,the proposed method is verified by simulations and experiments.
基金Supported by the National Natural Science Foundation of China under Grants 52207211,U2166601,51937003,U23A20655by the Fundamental Research Funds for the Central Universities under Grants JZ2024HGTB0259.
文摘The integration of photovoltaic (PV) systems into weak-grid environments presents unique challenges to the stability of grid-connected inverters. This review provides a comprehensive overview of the research efforts focused on investigating the stability of PV grid-connected inverters that operate under weak grid conditions. Weak grids are characterized by a low short-circuit capacity and low inertia, making it essential to explore strategies that enhance the stability and performance of inverters in such challenging environments. This review covers various aspects, including control strategies and advanced technologies implemented to address stability problems. The research findings related to the impact of weak grid conditions on PV inverters, modeling techniques, and analysis results are discussed. Additionally, this review highlights emerging trends, identifies gaps in the current research, and suggests potential avenues for future investigations aimed at improving the stability of PV grid-connected inverters in weak grid scenarios.
