This research develops a comprehensive method to solve a combinatorial problem consisting of distribution system reconfiguration, capacitor allocation, and renewable energy resources sizing and siting simultaneously a...This research develops a comprehensive method to solve a combinatorial problem consisting of distribution system reconfiguration, capacitor allocation, and renewable energy resources sizing and siting simultaneously and to improve power system's accountability and system performance parameters. Due to finding solution which is closer to realistic characteristics, load forecasting, market price errors and the uncertainties related to the variable output power of wind based DG units are put in consideration. This work employs NSGA-II accompanied by the fuzzy set theory to solve the aforementioned multi-objective problem. The proposed scheme finally leads to a solution with a minimum voltage deviation, a maximum voltage stability, lower amount of pollutant and lower cost. The cost includes the installation costs of new equipment, reconfiguration costs, power loss cost, reliability cost, cost of energy purchased from power market, upgrade costs of lines and operation and maintenance costs of DGs. Therefore, the proposed methodology improves power quality, reliability and security in lower costs besides its preserve, with the operational indices of power distribution networks in acceptable level. To validate the proposed methodology's usefulness, it was applied on the IEEE 33-bus distribution system then the outcomes were compared with initial configuration.展开更多
As the green and sustainable development of human society highly relies on renewable energy,it has been recognized that electrocatalysis is a key technology to this end.High efficient ways of carbon-neutralization(eCO...As the green and sustainable development of human society highly relies on renewable energy,it has been recognized that electrocatalysis is a key technology to this end.High efficient ways of carbon-neutralization(eCO_(2)RR),reverse artificial nitrogen cycle(RANC),and oxygen chemistry(OER and ORR)all can be driven by electrocatalysis.Advanced theoretical study is an important means to fundamentally understanding electrocatalytic reactions.Herein,we review a few significant issues in theoretical electrocatalysis.First,electrochemical barriers and potential effects are essential for a more accurate description of reaction mechanism and activity.Meanwhile,consideration of competitive reaction path is also one of the important aspects,as novel insights and anomalous volcano trend can be obtained.Finally,a microenvironment exerted by confined space can tune the capacitance of electrochemical interface and(electro)chemical potential of proton,resulting in a possibility to improve reaction activity,which opens a new avenue for design of catalyst.展开更多
In this paper, we investigate multi-scale methods for the inverse modeling in 1-D Metal-Oxide-Silicon (MOS) capacitor. First, the mathematical model of the device is given and the numerical simulation for the forward ...In this paper, we investigate multi-scale methods for the inverse modeling in 1-D Metal-Oxide-Silicon (MOS) capacitor. First, the mathematical model of the device is given and the numerical simulation for the forward problem of the model is implemented using finite element method with adaptive moving mesh. Then numerical analysis of these parameters in the model for the inverse problem is presented. Some matrix analysis tools are applied to explore the parameters' sensitivities. And third, the parameters are extracted using Levenberg-Marquardt optimization method. The essential difficulty arises from the effect of multi-scale physical difference of the parameters. We explore the relationship between the parameters' sensitivities and the sequence for optimization, which can seriously affect the final inverse modeling results. An optimal sequence can efficiently overcome the multi-scale problem of these parameters. Numerical experiments show the efficiency of the proposed methods.展开更多
This study establishes for the first time a P2D-coupled non-ideal double-layer capacitor model(P2D-CNIC),which can be used for mechanism analysis under high-frequency periodic signal excitation.The novelty of this wor...This study establishes for the first time a P2D-coupled non-ideal double-layer capacitor model(P2D-CNIC),which can be used for mechanism analysis under high-frequency periodic signal excitation.The novelty of this work is the consideration of the generally neglected electric double-layer capacitance and its dispersion effects,especially the capacitance of the solid electrolyte interface(SEI)film.The dispersion effect of the model is verified by a periodic current excitation signal and the corresponding phase change in the voltage response.Under sinusoidal alternating current(AC)excitation,a comparative analysis was conducted between the traditional P2D model,the traditional P2D model coupled with the ideal double-layer capacitor(P2D-CIC),and the proposed P2D-CNIC mechanism model.Furthermore,three models were evaluated under periodic short-circuit pulse discharge conditions to verify the accuracy and reliability of P2D-CNIC.The simulation results are used to analyze the dominant order of faradaic and non-Faraday processes under sinusoidal AC excitation,thereby providing insights into the internal mechanism analysis of lithium batteries under high-frequency cycling conditions.展开更多
Although triboelectrification(TE)is essential in many industrial and scientific fields,its charge transfer mechanisms are still not fully understood.In this paper,the charging-induced electric potential on the frictio...Although triboelectrification(TE)is essential in many industrial and scientific fields,its charge transfer mechanisms are still not fully understood.In this paper,the charging-induced electric potential on the friction surface and the discharging-induced light emission from the contact region during sliding frictions between insulators have been observed simultaneously.The results show that,in the absence of discharging,the temporal variations of surface potential at all the contact points are almost the same,experiencing a rapid growth in the initial stage,followed by a slow growth,and eventually reaching a stable value.To explain such a dynamics of electron transfer,a theoretical expression for the temporal evolution of the surface potential during TE process is proposed by considering the electron transfer as the charging process of a capacitor formed by contacting surfaces,and is found consistent with the experimental measurements.The experiments further indicate that,when discharging occurs,it has no influence on the charging process of the initially negatively charged surface,but can greatly change the charging of the initially positively charged surface,on which the potential will increase initially,soon begin to decrease,and eventually reach a stable value.Such a significant difference in the potential variation when discharging occurs can be attributed to the huge difference in mass between electrons and positive ions produced in the discharging process.The present work may offer a new perspective for understanding the electron transfer dynamics in TE and may provide potential applications in numerous fields involving TE.展开更多
Triboelectric nanogenerator(TENG) is an emerging powerful technology for converting ambient mechanical energy into electrical energy through the effect of triboelectricity. Starting from the expanded Maxwell’s equati...Triboelectric nanogenerator(TENG) is an emerging powerful technology for converting ambient mechanical energy into electrical energy through the effect of triboelectricity. Starting from the expanded Maxwell’s equations, the theoretical framework of TENGs has been gradually established. Here, a review is given about its recent progress in constructing of this general theory. The fundamental mechanism of TENGs is constructed by the driving force—Maxwell’s displacement current, which is essentially different from that of electromagnetic generators. Theoretical calculations of the displacement current from a threedimensional mathematical model are presented, as well as the theoretical studies on the TENGs according to the capacitor models. Furthermore, the figure-of-merits and standards for quantifying the TENG’s output characteristics are discussed, which will provide important guidelines for optimizing the structure and performance of TENGs toward practical applications. Finally,perspectives and challenges are proposed about the basic theory of TENGs and its future technology development.展开更多
This paper investigates the capacitance-voltage （C-V） measurement on fully silicided （FUSI） gated metal-oxide-semiconductor （MOS） capacitors and the applicability of MOS capacitor models. When the oxide leakage ...This paper investigates the capacitance-voltage （C-V） measurement on fully silicided （FUSI） gated metal-oxide-semiconductor （MOS） capacitors and the applicability of MOS capacitor models. When the oxide leakage current of an MOS capacitor is large, two-element parallel or series model cannot be used to obtain its real C-V characteristic. A three-element model simultaneously consisting of parallel conductance and series resistance or a four-element model with further consideration of a series inductance should be used. We employed the threeelement and the four-element models with the help of two-frequency technique to measure the Ni FUSI gated MOS capacitors. The results indicate that the capacitance of the MOS capacitors extracted by the three-element model still shows some frequency dispersion, while that extracted by the four-element model is close to the real capacitance, showing little frequency dispersion. The obtained capacitance can be used to calculate the dielectric thickness with quantum effect correction by NCSU C-V program. We also investigated the influence of MOS capacitor＇s area on the measurement accuracy. The results indicate that the decrease of capacitor area can reduce the dissipation factor and improve the measurement accuracy. As a result, the frequency dispersion of the measured capacitance is significantly reduced, and real C-V characteristic can be obtained directly by the series model. In addition, this paper investigates the quasi-static C-V measurement and the photonic high-frequency C-V measurement on Ni FUSI metal gated MOS capacitor with a thin leaky oxide. The results indicate that the large tunneling current through the gate oxide significantly perturbs the accurate measurement of the displacement current, which is essential for the quasi-static C-V measurement. On the other hand, the photonic high-frequency C-V measurement can bypass the leakage problem, and get reliable low-frequency C-V characteristic, which can be used to evaluate whether the full silicidation has completed or not, and to extract the interface trap density of the SiO2/Si interface.展开更多
文摘This research develops a comprehensive method to solve a combinatorial problem consisting of distribution system reconfiguration, capacitor allocation, and renewable energy resources sizing and siting simultaneously and to improve power system's accountability and system performance parameters. Due to finding solution which is closer to realistic characteristics, load forecasting, market price errors and the uncertainties related to the variable output power of wind based DG units are put in consideration. This work employs NSGA-II accompanied by the fuzzy set theory to solve the aforementioned multi-objective problem. The proposed scheme finally leads to a solution with a minimum voltage deviation, a maximum voltage stability, lower amount of pollutant and lower cost. The cost includes the installation costs of new equipment, reconfiguration costs, power loss cost, reliability cost, cost of energy purchased from power market, upgrade costs of lines and operation and maintenance costs of DGs. Therefore, the proposed methodology improves power quality, reliability and security in lower costs besides its preserve, with the operational indices of power distribution networks in acceptable level. To validate the proposed methodology's usefulness, it was applied on the IEEE 33-bus distribution system then the outcomes were compared with initial configuration.
文摘As the green and sustainable development of human society highly relies on renewable energy,it has been recognized that electrocatalysis is a key technology to this end.High efficient ways of carbon-neutralization(eCO_(2)RR),reverse artificial nitrogen cycle(RANC),and oxygen chemistry(OER and ORR)all can be driven by electrocatalysis.Advanced theoretical study is an important means to fundamentally understanding electrocatalytic reactions.Herein,we review a few significant issues in theoretical electrocatalysis.First,electrochemical barriers and potential effects are essential for a more accurate description of reaction mechanism and activity.Meanwhile,consideration of competitive reaction path is also one of the important aspects,as novel insights and anomalous volcano trend can be obtained.Finally,a microenvironment exerted by confined space can tune the capacitance of electrochemical interface and(electro)chemical potential of proton,resulting in a possibility to improve reaction activity,which opens a new avenue for design of catalyst.
基金This project is supported by Motorola (China) Electronics Ltd. and the work of Pingwen Zhang is also partially supported by Special Funds for Major State Basic Research Projects of China G1999032804.
文摘In this paper, we investigate multi-scale methods for the inverse modeling in 1-D Metal-Oxide-Silicon (MOS) capacitor. First, the mathematical model of the device is given and the numerical simulation for the forward problem of the model is implemented using finite element method with adaptive moving mesh. Then numerical analysis of these parameters in the model for the inverse problem is presented. Some matrix analysis tools are applied to explore the parameters' sensitivities. And third, the parameters are extracted using Levenberg-Marquardt optimization method. The essential difficulty arises from the effect of multi-scale physical difference of the parameters. We explore the relationship between the parameters' sensitivities and the sequence for optimization, which can seriously affect the final inverse modeling results. An optimal sequence can efficiently overcome the multi-scale problem of these parameters. Numerical experiments show the efficiency of the proposed methods.
基金supported by the National Natural Science Foundation of China(grant no.52177206)the Joint Funds of Equipment Pre-Research and Ministry of Education of China(grant no.8091B022130).
文摘This study establishes for the first time a P2D-coupled non-ideal double-layer capacitor model(P2D-CNIC),which can be used for mechanism analysis under high-frequency periodic signal excitation.The novelty of this work is the consideration of the generally neglected electric double-layer capacitance and its dispersion effects,especially the capacitance of the solid electrolyte interface(SEI)film.The dispersion effect of the model is verified by a periodic current excitation signal and the corresponding phase change in the voltage response.Under sinusoidal alternating current(AC)excitation,a comparative analysis was conducted between the traditional P2D model,the traditional P2D model coupled with the ideal double-layer capacitor(P2D-CIC),and the proposed P2D-CNIC mechanism model.Furthermore,three models were evaluated under periodic short-circuit pulse discharge conditions to verify the accuracy and reliability of P2D-CNIC.The simulation results are used to analyze the dominant order of faradaic and non-Faraday processes under sinusoidal AC excitation,thereby providing insights into the internal mechanism analysis of lithium batteries under high-frequency cycling conditions.
基金supported by the National Natural Science Foundation of China(52375166).
文摘Although triboelectrification(TE)is essential in many industrial and scientific fields,its charge transfer mechanisms are still not fully understood.In this paper,the charging-induced electric potential on the friction surface and the discharging-induced light emission from the contact region during sliding frictions between insulators have been observed simultaneously.The results show that,in the absence of discharging,the temporal variations of surface potential at all the contact points are almost the same,experiencing a rapid growth in the initial stage,followed by a slow growth,and eventually reaching a stable value.To explain such a dynamics of electron transfer,a theoretical expression for the temporal evolution of the surface potential during TE process is proposed by considering the electron transfer as the charging process of a capacitor formed by contacting surfaces,and is found consistent with the experimental measurements.The experiments further indicate that,when discharging occurs,it has no influence on the charging process of the initially negatively charged surface,but can greatly change the charging of the initially positively charged surface,on which the potential will increase initially,soon begin to decrease,and eventually reach a stable value.Such a significant difference in the potential variation when discharging occurs can be attributed to the huge difference in mass between electrons and positive ions produced in the discharging process.The present work may offer a new perspective for understanding the electron transfer dynamics in TE and may provide potential applications in numerous fields involving TE.
基金supported by the National Key R&D Project from Minister of Science and Technology, China (Grant No. 2016YFA0202704)National Natural Science Foundation of China (Grant Nos. 51432005, 51702018, and 51561145021)Youth Innovation Promotion Association, CAS, and China Postdoctoral Science Foundation (Grant No. 2019M660766)。
文摘Triboelectric nanogenerator(TENG) is an emerging powerful technology for converting ambient mechanical energy into electrical energy through the effect of triboelectricity. Starting from the expanded Maxwell’s equations, the theoretical framework of TENGs has been gradually established. Here, a review is given about its recent progress in constructing of this general theory. The fundamental mechanism of TENGs is constructed by the driving force—Maxwell’s displacement current, which is essentially different from that of electromagnetic generators. Theoretical calculations of the displacement current from a threedimensional mathematical model are presented, as well as the theoretical studies on the TENGs according to the capacitor models. Furthermore, the figure-of-merits and standards for quantifying the TENG’s output characteristics are discussed, which will provide important guidelines for optimizing the structure and performance of TENGs toward practical applications. Finally,perspectives and challenges are proposed about the basic theory of TENGs and its future technology development.
基金supported by the National Natural Science Foundation of China (Nos. 60576029, 90607018)the Science and TechnologyCommittee of Shanghai Municipality (No. 07QA14004)+1 种基金the Shanghai-Applied Materials Research Development Fund (No. 07SA06)Fok Ying Tong Education Foundation (No. 114006).
文摘This paper investigates the capacitance-voltage （C-V） measurement on fully silicided （FUSI） gated metal-oxide-semiconductor （MOS） capacitors and the applicability of MOS capacitor models. When the oxide leakage current of an MOS capacitor is large, two-element parallel or series model cannot be used to obtain its real C-V characteristic. A three-element model simultaneously consisting of parallel conductance and series resistance or a four-element model with further consideration of a series inductance should be used. We employed the threeelement and the four-element models with the help of two-frequency technique to measure the Ni FUSI gated MOS capacitors. The results indicate that the capacitance of the MOS capacitors extracted by the three-element model still shows some frequency dispersion, while that extracted by the four-element model is close to the real capacitance, showing little frequency dispersion. The obtained capacitance can be used to calculate the dielectric thickness with quantum effect correction by NCSU C-V program. We also investigated the influence of MOS capacitor＇s area on the measurement accuracy. The results indicate that the decrease of capacitor area can reduce the dissipation factor and improve the measurement accuracy. As a result, the frequency dispersion of the measured capacitance is significantly reduced, and real C-V characteristic can be obtained directly by the series model. In addition, this paper investigates the quasi-static C-V measurement and the photonic high-frequency C-V measurement on Ni FUSI metal gated MOS capacitor with a thin leaky oxide. The results indicate that the large tunneling current through the gate oxide significantly perturbs the accurate measurement of the displacement current, which is essential for the quasi-static C-V measurement. On the other hand, the photonic high-frequency C-V measurement can bypass the leakage problem, and get reliable low-frequency C-V characteristic, which can be used to evaluate whether the full silicidation has completed or not, and to extract the interface trap density of the SiO2/Si interface.
