Purpose–This study aims to propose a vertical coupling dynamic analysis method of vehicle–track–substructure based on forced vibration and use this method to analyze the influence on the dynamic response of track a...Purpose–This study aims to propose a vertical coupling dynamic analysis method of vehicle–track–substructure based on forced vibration and use this method to analyze the influence on the dynamic response of track and vehicle caused by local fastener failure.Design/methodology/approach–The track and substructure are decomposed into the rail subsystem and substructure subsystem,in which the rail subsystem is composed of two layers of nodes corresponding to the upper rail and the lower fastener.The rail is treated as a continuous beam with elastic discrete point supports,and spring-damping elements are used to simulate the constraints between rail and fastener.Forced displacement and forced velocity are used to deal with the effect of the substructure on the rail system,while the external load is used to deal with the reverse effect.The fastener failure is simulated with the methods that cancel the forced vibration transmission,namely take no account of the substructure–rail interaction at that position.Findings–The dynamic characteristics of the infrastructure with local diseases can be accurately calculated by using the proposed method.Local fastener failure will slightly affect the vibration of substructure and carbody,but it will significantly intensify the vibration response between wheel and rail.The maximum vertical displacement and the maximum vertical vibration acceleration of rail is 2.94 times and 2.97 times the normal value,respectively,under the train speed of 350 km$h1.At the same time,the maximum wheel–rail force and wheel load reduction rate increase by 22.0 and 50.2%,respectively,from the normal value.Originality/value–This method can better reveal the local vibration conditions of the rail and easily simulate the influence of various defects on the dynamic response of the coupling system.展开更多
Herein we propose a new equivalent circuit including double heterojunctions in series to simulate the current–voltage characteristic of P–I–N planar structure perovskite solar cells. This new method can theoretical...Herein we propose a new equivalent circuit including double heterojunctions in series to simulate the current–voltage characteristic of P–I–N planar structure perovskite solar cells. This new method can theoretically solve the dilemma of the parameter diode ideal factor being larger than2 from an ideal single heterojunction equivalent circuit,which usually is in the range from 1 to 2. The diode ideal factor reflects PN junction quality, which influences the recombination at electron transport layer/perovskite and perovskite/hole transport layer interface. Based on the double PN junction equivalent circuit, we can also simulate the dark current–voltage curve for analyzing recombination current(Shockley–Read–Hall recombination) and diffusion current(including direct recombination), and thus carrier recombination and transportation characteristics. This new model offers an efficacious and simple method to investigate interfaces condition, film quality of perovskite absorbing layer and performance of transport layer, helping us furtherimprove the device efficiency and analyze the working mechanism.展开更多
Comprehensive Summary The configuration of the anomeric glycosidic linkages is crucial for maintaining the biological functions and activities of carbohydrate molecules.However,their stereochemistry control in glycosy...Comprehensive Summary The configuration of the anomeric glycosidic linkages is crucial for maintaining the biological functions and activities of carbohydrate molecules.However,their stereochemistry control in glycosylation represents one of the most challenging tasks in carbohydrate chemistry.展开更多
In scenarios of quantum metrology, the unitary parametrization process often depends on space directions. How to characterize the sensitivity of parameter estimation to space directions is a natural question. We propo...In scenarios of quantum metrology, the unitary parametrization process often depends on space directions. How to characterize the sensitivity of parameter estimation to space directions is a natural question. We propose the concept of the quantum Fisher information(QFI) width, which is the difference between the maximum and minimum values of the QFI, to quantitatively study the sensitivity. We find that Fock states, the bosonic coherent states, and the displaced Fock states all have zero widths, indicating that QFI is completely inert over all directions, while the width for the spin state with all spins down or up is equal to the number of particles, so this concept will enable us to choose appropriate directions to make unitary transformation to obtain larger QFI.The QFI width of the displaced quantum states is found to be independent of the magnitude of the displacement for both spin and bosonic systems. We also find some relations between the QFI width and squeezing parameters.展开更多
基金funded by the Research Fund of Shanghai Bureau Group Corporation(2021142)Science Foundation of China State Railway Group Corporation Limited(P2021T013)and Science Foundation of China Academy of Railway Sciences Corporation Limited(2021YJ250).
文摘Purpose–This study aims to propose a vertical coupling dynamic analysis method of vehicle–track–substructure based on forced vibration and use this method to analyze the influence on the dynamic response of track and vehicle caused by local fastener failure.Design/methodology/approach–The track and substructure are decomposed into the rail subsystem and substructure subsystem,in which the rail subsystem is composed of two layers of nodes corresponding to the upper rail and the lower fastener.The rail is treated as a continuous beam with elastic discrete point supports,and spring-damping elements are used to simulate the constraints between rail and fastener.Forced displacement and forced velocity are used to deal with the effect of the substructure on the rail system,while the external load is used to deal with the reverse effect.The fastener failure is simulated with the methods that cancel the forced vibration transmission,namely take no account of the substructure–rail interaction at that position.Findings–The dynamic characteristics of the infrastructure with local diseases can be accurately calculated by using the proposed method.Local fastener failure will slightly affect the vibration of substructure and carbody,but it will significantly intensify the vibration response between wheel and rail.The maximum vertical displacement and the maximum vertical vibration acceleration of rail is 2.94 times and 2.97 times the normal value,respectively,under the train speed of 350 km$h1.At the same time,the maximum wheel–rail force and wheel load reduction rate increase by 22.0 and 50.2%,respectively,from the normal value.Originality/value–This method can better reveal the local vibration conditions of the rail and easily simulate the influence of various defects on the dynamic response of the coupling system.
基金the 973 Program of China(No.2014CB643506 and 2013CB922104)the China Scholarship Council(No.201506165038)+3 种基金the Natural Science Foundation of China(No.21673091)the Natural Science Foundation of Hubei Province(No.ZRZ2015000203)Technology Creative Project of Excellent Middle and Young Team of Hubei Province(No.T201511)the Wuhan National High Magnetic Field Center(2015KF18)is acknowledged
文摘Herein we propose a new equivalent circuit including double heterojunctions in series to simulate the current–voltage characteristic of P–I–N planar structure perovskite solar cells. This new method can theoretically solve the dilemma of the parameter diode ideal factor being larger than2 from an ideal single heterojunction equivalent circuit,which usually is in the range from 1 to 2. The diode ideal factor reflects PN junction quality, which influences the recombination at electron transport layer/perovskite and perovskite/hole transport layer interface. Based on the double PN junction equivalent circuit, we can also simulate the dark current–voltage curve for analyzing recombination current(Shockley–Read–Hall recombination) and diffusion current(including direct recombination), and thus carrier recombination and transportation characteristics. This new model offers an efficacious and simple method to investigate interfaces condition, film quality of perovskite absorbing layer and performance of transport layer, helping us furtherimprove the device efficiency and analyze the working mechanism.
基金supported by the National Natural Science Foundation of China(Nos.21977115 and 21672248).
文摘Comprehensive Summary The configuration of the anomeric glycosidic linkages is crucial for maintaining the biological functions and activities of carbohydrate molecules.However,their stereochemistry control in glycosylation represents one of the most challenging tasks in carbohydrate chemistry.
基金supported by the National Key Research and Development Program of China(Grant Nos.2017YFA0304202,and 2017YFA0205700)the National Natural Science Foundation of China(Grant No.11475146)+2 种基金the Fundamental Research Funds for the Central Universities(Grant No.2018FZA3005)support by the Thirteenth Fiveyear Planning Project of Jilin Provincial Education Department Foundation(Grant No.JJKH20170650KJ)the Natural Science Foundation of Changchun Normal University
文摘In scenarios of quantum metrology, the unitary parametrization process often depends on space directions. How to characterize the sensitivity of parameter estimation to space directions is a natural question. We propose the concept of the quantum Fisher information(QFI) width, which is the difference between the maximum and minimum values of the QFI, to quantitatively study the sensitivity. We find that Fock states, the bosonic coherent states, and the displaced Fock states all have zero widths, indicating that QFI is completely inert over all directions, while the width for the spin state with all spins down or up is equal to the number of particles, so this concept will enable us to choose appropriate directions to make unitary transformation to obtain larger QFI.The QFI width of the displaced quantum states is found to be independent of the magnitude of the displacement for both spin and bosonic systems. We also find some relations between the QFI width and squeezing parameters.