In this study,the effects of various surface treatments on the friction and wear behavior of AISI 4140 steel have been evaluated.Sample surfaces of AISI 4140 steel were treated by quenching,carburizing,boronizing and ...In this study,the effects of various surface treatments on the friction and wear behavior of AISI 4140 steel have been evaluated.Sample surfaces of AISI 4140 steel were treated by quenching,carburizing,boronizing and plasma transferred arc （PTA） modification.The microstructural characteristics of surface treated steel samples were examined by optical microscopy and scanning electron microscopy （SEM）.The mechanical properties of the samples including the surface roughness,microhardness,and abrasive and adhesive wear characteristics were also evaluated.Wear tests were applied by using a block-on-disc configuration under dry sliding conditions.The wear behavior and friction characteristics of the samples were determined as a function of sliding distance.Each sample group was compared with the other sample groups,and it was observed that the carburized samples demonstrated the lowest weight losses;however,PTA-treated samples demonstrated the lowest coefficient of friction in comparison to the other sample groups at the same sliding distance.展开更多
Heavy flavor particles provide important probes of the microscopic structure and thermodynamic properties of the quark-gluon plasma(QGP)produced in high-energy nucleus-nucleus collisions.We studied the energy loss and...Heavy flavor particles provide important probes of the microscopic structure and thermodynamic properties of the quark-gluon plasma(QGP)produced in high-energy nucleus-nucleus collisions.We studied the energy loss and flow of charm and bottom quarks inside the QGP via the nuclear modification factor(R_(AA))and elliptic flow coefficient(v_(2))of their decayed leptons in heavy-ion collisions at the LHC.The dynamical evolution of the QGP was performed using the CLVisc(3+1)-dimensional viscous hydrodynamics model;the evolution of heavy quarks inside the QGP was simulated with our improved Langevin model that considers both collisional and radiative energy loss of heavy quarks;the hadronization of heavy quarks was simulated via our hybrid coalescence-fragmentation model;and the semi-leptonic decay of D and B mesons was simulated via PYTHIA.Using the same spatial diffusion coefficient for charm and bottom quarks,we obtained smaller R_(AA) and larger v_(2) of charm decayed leptons than bottom decayed leptons,indicating stronger energy loss of charm quarks than bottom quarks inside the QGP within our current model setup.展开更多
We present a theoretical study of the medium modifications of the p_(T)balance (x_(J)) of dijets in Xe+Xe collisions at■.The initial production of dijets was carried out using the POWHEG+PYTHIA8 prescription,which ma...We present a theoretical study of the medium modifications of the p_(T)balance (x_(J)) of dijets in Xe+Xe collisions at■.The initial production of dijets was carried out using the POWHEG+PYTHIA8 prescription,which matches the next-toleading-order (NLO) QCD matrix elements with the parton shower (PS) effect.The SHELL model described the in-medium evolution of nucleus–nucleus collisions using a transport approach.The theoretical results of the dijet xJin the Xe+Xe collisions exhibit more imbalanced distributions than those in the p+p collisions,consistent with recently reported ATLAS data.By utilizing the Interleaved Flavor Neutralisation,an infrared-and-collinear-safe jet flavor algorithm,to identify the flavor of the reconstructed jets,we classify dijets processes into three categories:gluon–gluon (gg),quark–gluon (qg),and quark–quark (qq),and investigated the respective medium modification patterns and fraction changes of the gg,qg,and qq components of the dijet sample in Xe+Xe collisions.It is shown that the increased fraction of qg component at a small x_(J)contributes to the imbalance of the dijet;in particular,the q_(1)g_(2)(quark-jet-leading) dijets experience more significant asymmetric energy loss than the g_(1)q_(2)(gluon-jet-leading) dijets traversing the QGP.By comparing the■of inclusive,■ dijets in Xe+Xe collisions,we observe■.Moreover,ρ_(Xe),P_(b),the ratios of the nuclear modification factors of dijets in Xe+Xe to those in Pb+Pb,were calculated,which indicates that the yield suppression of dijets in Pb+Pb is more pronounced than that in Xe+Xe owing to the larger radius of the lead nucleus.展开更多
The production of vector boson tagged heavy quark jets potentially provides new tools to probe the jet quenching effect.In this paper,we present the first theoretical study on the angular correlations(ΔφbZ),transver...The production of vector boson tagged heavy quark jets potentially provides new tools to probe the jet quenching effect.In this paper,we present the first theoretical study on the angular correlations(ΔφbZ),transverse momentum imbalance(xbZ),and nuclear modification factor(IAA) of Z0boson tagged b-jets in heavy-ion collisions,which was performed using a Monte Carlo transport model.We find that the medium modification of theΔφbZfor Z0+b-jet has a weaker dependence on ΔφbZthan that for Z^(0)+jet,and the modification patterns are sensitive to the initial jet pTdistribution.Additionally,with the high purity of the quark jet in Z^(0)+(b-) jet production,we calculate the momentum imbalance xbZand the nuclear modification factor IAAof Z^(0)+b-jet in Pb+Pb collisions.We observe a smaller Δ<xjZ> and larger IAAof Z^(0)+b-jet in Pb+Pb collisions relative to those of Z^(0)+jet,which may be an indication of the mass effect of jet quenching and can be tested in future measurements.展开更多
Jet quenching has successfully served as a hard probe to study the properties of Quark-Gluon Plasma(QGP).As a multi-particle system,jets require time to develop from a highly virtual parton to a group of partons close...Jet quenching has successfully served as a hard probe to study the properties of Quark-Gluon Plasma(QGP).As a multi-particle system,jets require time to develop from a highly virtual parton to a group of partons close to mass shells.In this study,we present a systematical analysis on the effects of this formation time on jet quenching in relativistic nuclear collisions.Jets from initial hard scatterings were simulated with Pythia,and their interactions with QGP were described using a Linear Boltzmann Transport(LBT) model that incorporates both elastic and inelastic scatterings between jet partons and the thermal medium.Three different estimations of the jet formation time were implemented and compared,including instantaneous formation,formation from single splitting,and formation from sequential splittings,before which no jet-medium interaction was assumed.We found that deferring the jet-medium interaction with a longer formation time not only affects the overall magnitude of the nuclear modification factor of jets but also its dependence on the jet transverse momentum.展开更多
基金supported by the Eskisehir Osmangazi University Research Council (No. 200315015)
文摘In this study,the effects of various surface treatments on the friction and wear behavior of AISI 4140 steel have been evaluated.Sample surfaces of AISI 4140 steel were treated by quenching,carburizing,boronizing and plasma transferred arc （PTA） modification.The microstructural characteristics of surface treated steel samples were examined by optical microscopy and scanning electron microscopy （SEM）.The mechanical properties of the samples including the surface roughness,microhardness,and abrasive and adhesive wear characteristics were also evaluated.Wear tests were applied by using a block-on-disc configuration under dry sliding conditions.The wear behavior and friction characteristics of the samples were determined as a function of sliding distance.Each sample group was compared with the other sample groups,and it was observed that the carburized samples demonstrated the lowest weight losses;however,PTA-treated samples demonstrated the lowest coefficient of friction in comparison to the other sample groups at the same sliding distance.
基金Supported in part by the National Natural Science Foundation of China(12225503,11935007,11890710,11890711,12175122,2021-867)China Postdoctoral Science Foundation(2023M742099)。
文摘Heavy flavor particles provide important probes of the microscopic structure and thermodynamic properties of the quark-gluon plasma(QGP)produced in high-energy nucleus-nucleus collisions.We studied the energy loss and flow of charm and bottom quarks inside the QGP via the nuclear modification factor(R_(AA))and elliptic flow coefficient(v_(2))of their decayed leptons in heavy-ion collisions at the LHC.The dynamical evolution of the QGP was performed using the CLVisc(3+1)-dimensional viscous hydrodynamics model;the evolution of heavy quarks inside the QGP was simulated with our improved Langevin model that considers both collisional and radiative energy loss of heavy quarks;the hadronization of heavy quarks was simulated via our hybrid coalescence-fragmentation model;and the semi-leptonic decay of D and B mesons was simulated via PYTHIA.Using the same spatial diffusion coefficient for charm and bottom quarks,we obtained smaller R_(AA) and larger v_(2) of charm decayed leptons than bottom decayed leptons,indicating stronger energy loss of charm quarks than bottom quarks inside the QGP within our current model setup.
基金Guangdong Major Project of Basic and Applied Basic Research(No.2020B0301030008)National Natural Science Foundation of China with Project(Nos.11935007,12035007,12247127,and 12247132)China Postdoctoral Science Foundation supports S.Wang under project No.2021M701279.
文摘We present a theoretical study of the medium modifications of the p_(T)balance (x_(J)) of dijets in Xe+Xe collisions at■.The initial production of dijets was carried out using the POWHEG+PYTHIA8 prescription,which matches the next-toleading-order (NLO) QCD matrix elements with the parton shower (PS) effect.The SHELL model described the in-medium evolution of nucleus–nucleus collisions using a transport approach.The theoretical results of the dijet xJin the Xe+Xe collisions exhibit more imbalanced distributions than those in the p+p collisions,consistent with recently reported ATLAS data.By utilizing the Interleaved Flavor Neutralisation,an infrared-and-collinear-safe jet flavor algorithm,to identify the flavor of the reconstructed jets,we classify dijets processes into three categories:gluon–gluon (gg),quark–gluon (qg),and quark–quark (qq),and investigated the respective medium modification patterns and fraction changes of the gg,qg,and qq components of the dijet sample in Xe+Xe collisions.It is shown that the increased fraction of qg component at a small x_(J)contributes to the imbalance of the dijet;in particular,the q_(1)g_(2)(quark-jet-leading) dijets experience more significant asymmetric energy loss than the g_(1)q_(2)(gluon-jet-leading) dijets traversing the QGP.By comparing the■of inclusive,■ dijets in Xe+Xe collisions,we observe■.Moreover,ρ_(Xe),P_(b),the ratios of the nuclear modification factors of dijets in Xe+Xe to those in Pb+Pb,were calculated,which indicates that the yield suppression of dijets in Pb+Pb is more pronounced than that in Xe+Xe owing to the larger radius of the lead nucleus.
基金Supported by the Guangdong Major Project of Basic and Applied Basic Research (2020B0301030008)the Science and Technology Program of Guangzhou(2019050001)+1 种基金the NSFC of China (11935007,12035007,12247127)supported by China Postdoctoral Science Foundation (2021M701279)
文摘The production of vector boson tagged heavy quark jets potentially provides new tools to probe the jet quenching effect.In this paper,we present the first theoretical study on the angular correlations(ΔφbZ),transverse momentum imbalance(xbZ),and nuclear modification factor(IAA) of Z0boson tagged b-jets in heavy-ion collisions,which was performed using a Monte Carlo transport model.We find that the medium modification of theΔφbZfor Z0+b-jet has a weaker dependence on ΔφbZthan that for Z^(0)+jet,and the modification patterns are sensitive to the initial jet pTdistribution.Additionally,with the high purity of the quark jet in Z^(0)+(b-) jet production,we calculate the momentum imbalance xbZand the nuclear modification factor IAAof Z^(0)+b-jet in Pb+Pb collisions.We observe a smaller Δ<xjZ> and larger IAAof Z^(0)+b-jet in Pb+Pb collisions relative to those of Z^(0)+jet,which may be an indication of the mass effect of jet quenching and can be tested in future measurements.
基金Supported by the National Natural Science Foundation of China (12175122, 2021-867, 11890710, 11890713, 14-547)。
文摘Jet quenching has successfully served as a hard probe to study the properties of Quark-Gluon Plasma(QGP).As a multi-particle system,jets require time to develop from a highly virtual parton to a group of partons close to mass shells.In this study,we present a systematical analysis on the effects of this formation time on jet quenching in relativistic nuclear collisions.Jets from initial hard scatterings were simulated with Pythia,and their interactions with QGP were described using a Linear Boltzmann Transport(LBT) model that incorporates both elastic and inelastic scatterings between jet partons and the thermal medium.Three different estimations of the jet formation time were implemented and compared,including instantaneous formation,formation from single splitting,and formation from sequential splittings,before which no jet-medium interaction was assumed.We found that deferring the jet-medium interaction with a longer formation time not only affects the overall magnitude of the nuclear modification factor of jets but also its dependence on the jet transverse momentum.
