The prediction of wheel/rail rolling contact fatigue(RCF)crack initiation during railway operations is an important task.Since RCF crack evolution is influenced by many factors,its prediction process is complex.This p...The prediction of wheel/rail rolling contact fatigue(RCF)crack initiation during railway operations is an important task.Since RCF crack evolution is influenced by many factors,its prediction process is complex.This paper reviews the existing approaches to predict RCF crack initiation.The crack initiation region is predicted by the shakedown map.By combining the shakedown map with various initiation criteria and the critical plane method,the crack initiation life is calculated.The classification,methodologies,theories and applications of these approaches are included in this paper.The advantages and limitations of these methods are analyzed to provide recommendation for RCF crack initiation prediction.This review highlights that wheel/rail dynamic characteristic,complex working conditions,surface defects and wear all affect the RCF crack initiation.The optimal selection of criteria is essential in the crack initiation prediction.Based on the research gap regarding the challenging process of crack initiation prediction detailed in this review,a proposed prediction process of RCF crack initiation is proposed to achieve a more accurate result.展开更多
Feature parameters extraction is critical for speaker recognition research. The paper presents the function of pitch, formant and Mel frequency central coefficient (MFCC) in speaker recognition. It can increase the id...Feature parameters extraction is critical for speaker recognition research. The paper presents the function of pitch, formant and Mel frequency central coefficient (MFCC) in speaker recognition. It can increase the identification rate effectively for feature parameter sorts the speech corpus. Using Euclid Distance to compare feature parameters is very effective.展开更多
Solar-driven seawater desalination has attracted much attention for alleviating global freshwater shortage,but the practical application is often limited by complicated fabrication processes,unsatisfactory seawater-tr...Solar-driven seawater desalination has attracted much attention for alleviating global freshwater shortage,but the practical application is often limited by complicated fabrication processes,unsatisfactory seawater-transferring and severe salt accu-mulation on the photothermal membranes.To solve these problems,hydrophobic industrial-grade carbon fiber membrane(CFM)with good photoabsorption was surface-modified with polydopamine(PDA)to prepare superhydrophilic CFM@PDA for the construction of efficient hanging-model evaporators without salt accumulation.The coating of PDA on CFM is realized by simple self-polymerization of dopamine,and the as-prepared CFM@PDA exhibits high solar absorption effi-ciency of 96.7%,good photothermal effect and superhydrophilicity.Especially,when CFM@PDA is hanging between two water tanks(one contains seawater and the other is empty)in a flat hanging-model evaporator,it can transport seawater at a high rate(26.35 g/h)which is 3.6 times that(7.28 g/h)of commercial cotton fabric.Under simulated sunlight(1.0 kW m^(-2))irradiation,CFM@PDA shows a high evaporation rate of 1.79 kg m^(-2) h^(-1) with a solar evaporation efficiency of 92.6%.Even if NaCl solution with a high concentration(21.0 wt%)is used for the evaporation,the hanging CFM@PDA can retain a high evaporation rate(~1.80 kg m^(-2) h^(-1))without salt accumulation during the long-time test(8 h),which is significantly better than that of the tradition floating model.Therefore,this study not only demonstrates the simple preparation of super-hydrophilic CFM@PDA,but also promotes the further practical applications of hanging-model evaporators for continuous salt-free desalination.展开更多
In railway network,friction is an important factor to consider in terms of the service behaviors of wheel-rail system.The objective of this study was to investigate the effect of a solid friction modifier(FM)in a rail...In railway network,friction is an important factor to consider in terms of the service behaviors of wheel-rail system.The objective of this study was to investigate the effect of a solid friction modifier(FM)in a railway environment.This was achieved by studying the friction,wear,and rolling contact fatigue(RCF)damage on the wheel-rail materials at different slip ratios.The results showed that when a solid FM was applied,the friction coefficient decreased.After the solid FM was separated from the wheel-rail interface,the friction coefficient gradually increased to its original level.With the application of the solid FM,the wear rates of the wheel-rail decreased.In addition,the thickness and hardness of the plastic deformation layers of the wheel-rail materials were reduced.The worn surfaces of the wheel-rail were dominated by pits and RCF cracks.Without the FM,RCF cracks ranged from 84 to 120μm,and subsurface cracks were generated.However,with the FM,RCF cracks ranged from 17 to 97μm and no subsurface cracks were generated.These findings indicate possible methods of improving the performance of railway rolling stock by managing friction,and reducing wear and permanent RCF damage affecting both the wheels and rails.展开更多
基金supported by National Natural Science Foundation of China(Nos.52202510,U21A20167,52272443 and 51975489)Autonomous Research Project of State Key Laboratory(Nos.2020TPL-T10 and 2022TPL-T04)+1 种基金For a scholarship to S.Y.Zhang,under the State Scholarship Fund of the China Scholarship Council(CSC)(No.202007000128)to pursue study in the Central Queensland University as a cotutelle PhD Student.Dr.Qing Wu is the recipient of an Australian Research Council Discovery Early Career Award(Project Number DE210100273)funded by the Australian Government.
文摘The prediction of wheel/rail rolling contact fatigue(RCF)crack initiation during railway operations is an important task.Since RCF crack evolution is influenced by many factors,its prediction process is complex.This paper reviews the existing approaches to predict RCF crack initiation.The crack initiation region is predicted by the shakedown map.By combining the shakedown map with various initiation criteria and the critical plane method,the crack initiation life is calculated.The classification,methodologies,theories and applications of these approaches are included in this paper.The advantages and limitations of these methods are analyzed to provide recommendation for RCF crack initiation prediction.This review highlights that wheel/rail dynamic characteristic,complex working conditions,surface defects and wear all affect the RCF crack initiation.The optimal selection of criteria is essential in the crack initiation prediction.Based on the research gap regarding the challenging process of crack initiation prediction detailed in this review,a proposed prediction process of RCF crack initiation is proposed to achieve a more accurate result.
文摘Feature parameters extraction is critical for speaker recognition research. The paper presents the function of pitch, formant and Mel frequency central coefficient (MFCC) in speaker recognition. It can increase the identification rate effectively for feature parameter sorts the speech corpus. Using Euclid Distance to compare feature parameters is very effective.
基金financially by National Key Research and Development Program of China(2022YFB3804902,2022YFB3804900)the National Natural Science Foundation of China(52161145406,51972056)+1 种基金Program of Shanghai Academic Research Leader(20XD1420200)the Natural Science Foundation of Shanghai(21ZR1402500).
文摘Solar-driven seawater desalination has attracted much attention for alleviating global freshwater shortage,but the practical application is often limited by complicated fabrication processes,unsatisfactory seawater-transferring and severe salt accu-mulation on the photothermal membranes.To solve these problems,hydrophobic industrial-grade carbon fiber membrane(CFM)with good photoabsorption was surface-modified with polydopamine(PDA)to prepare superhydrophilic CFM@PDA for the construction of efficient hanging-model evaporators without salt accumulation.The coating of PDA on CFM is realized by simple self-polymerization of dopamine,and the as-prepared CFM@PDA exhibits high solar absorption effi-ciency of 96.7%,good photothermal effect and superhydrophilicity.Especially,when CFM@PDA is hanging between two water tanks(one contains seawater and the other is empty)in a flat hanging-model evaporator,it can transport seawater at a high rate(26.35 g/h)which is 3.6 times that(7.28 g/h)of commercial cotton fabric.Under simulated sunlight(1.0 kW m^(-2))irradiation,CFM@PDA shows a high evaporation rate of 1.79 kg m^(-2) h^(-1) with a solar evaporation efficiency of 92.6%.Even if NaCl solution with a high concentration(21.0 wt%)is used for the evaporation,the hanging CFM@PDA can retain a high evaporation rate(~1.80 kg m^(-2) h^(-1))without salt accumulation during the long-time test(8 h),which is significantly better than that of the tradition floating model.Therefore,this study not only demonstrates the simple preparation of super-hydrophilic CFM@PDA,but also promotes the further practical applications of hanging-model evaporators for continuous salt-free desalination.
基金This study was supported by the National Key R&D Program Intergovernmental Key Items for International Scientific and Technological Innovation Cooperation(No.2018YFE0109400)Sichuan Science and Technology Program(No.2020YFH0057)+1 种基金Fundamental Research Funds for the Central Universities(No.2682020CX29)The study was also carried out under the Project 8JCH1042 with financial support from the Ministry of Education,Youth and Sports of the Czech Republic.
文摘In railway network,friction is an important factor to consider in terms of the service behaviors of wheel-rail system.The objective of this study was to investigate the effect of a solid friction modifier(FM)in a railway environment.This was achieved by studying the friction,wear,and rolling contact fatigue(RCF)damage on the wheel-rail materials at different slip ratios.The results showed that when a solid FM was applied,the friction coefficient decreased.After the solid FM was separated from the wheel-rail interface,the friction coefficient gradually increased to its original level.With the application of the solid FM,the wear rates of the wheel-rail decreased.In addition,the thickness and hardness of the plastic deformation layers of the wheel-rail materials were reduced.The worn surfaces of the wheel-rail were dominated by pits and RCF cracks.Without the FM,RCF cracks ranged from 84 to 120μm,and subsurface cracks were generated.However,with the FM,RCF cracks ranged from 17 to 97μm and no subsurface cracks were generated.These findings indicate possible methods of improving the performance of railway rolling stock by managing friction,and reducing wear and permanent RCF damage affecting both the wheels and rails.