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
4-Chlorophenoxyacetic acid(4-CPA),a synthetic plant regulator,has been banned due to its cumulative toxicity to humans.However,unqualified sampling remains common in the market.To address the poor sensitivity of 4-CPA...4-Chlorophenoxyacetic acid(4-CPA),a synthetic plant regulator,has been banned due to its cumulative toxicity to humans.However,unqualified sampling remains common in the market.To address the poor sensitivity of 4-CPA antibodies reported previously,a highly sensitive monoclonal antibody specific to 4-CPA was produced by rede-signing and synthesizing a novel hapten in this study.Additionally,a visual colorimetric immunosensor based onTMB^(2+)mediated etching of gold nanorods(Au NRs)was developed.The∆λof the localized surface plasmon resonance(LSPR)peak exhibited a linear dependence on the 4-CPA concentration in the range of 0.2-6.25 ngmL^(-1),with a low limit of detection(LOD)of 0.2 ngmL^(-1).Recovery tests(85.0%to 108%)and HPLC validation demonstrated the immunosensor’s accuracy and precision.This visual colorimetric immunosensor illustrates significant potential for rapid detection of 4-CPA in biological environments.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supported by the National Key Research and Development Program of China(2023YFF1105002)the Key Project of Guangdong Provincial High School,China(2022ZDZX2004).
文摘4-Chlorophenoxyacetic acid(4-CPA),a synthetic plant regulator,has been banned due to its cumulative toxicity to humans.However,unqualified sampling remains common in the market.To address the poor sensitivity of 4-CPA antibodies reported previously,a highly sensitive monoclonal antibody specific to 4-CPA was produced by rede-signing and synthesizing a novel hapten in this study.Additionally,a visual colorimetric immunosensor based onTMB^(2+)mediated etching of gold nanorods(Au NRs)was developed.The∆λof the localized surface plasmon resonance(LSPR)peak exhibited a linear dependence on the 4-CPA concentration in the range of 0.2-6.25 ngmL^(-1),with a low limit of detection(LOD)of 0.2 ngmL^(-1).Recovery tests(85.0%to 108%)and HPLC validation demonstrated the immunosensor’s accuracy and precision.This visual colorimetric immunosensor illustrates significant potential for rapid detection of 4-CPA in biological environments.
