By considering the concept of a unified single fluid model,referred to as modified Chaplygin gas(MCG),which amalgamates dark energy and dark matter,we explore the thermodynamic characteristics of charged anti-de Sitte...By considering the concept of a unified single fluid model,referred to as modified Chaplygin gas(MCG),which amalgamates dark energy and dark matter,we explore the thermodynamic characteristics of charged anti-de Sitter(AdS)black holes existing in an unconventional fluid accompanied by MCG.To accomplish this objective,we derive the equations of state by regarding the charge Q^(2) as a thermodynamic variable.The effects of MCG parameters on the critical thermodynamic quantities(ψ_(c),T_(c),Q_(c)^(2))are examined,followed by a detailed analysis of the Q^(2)-ψ diagram.To provide a clearer explanation of the phase transition,we present an analysis of the Gibbs free energy.It is important to note that if the Hawking temperature exceeds the critical temperature,a distinct pattern is observed known as swallowtail behavior.This indicates that the system undergoes a first-order phase transition from a smaller black hole to a larger one.The critical exponent of the system is found to be in complete agreement with that of the van der Waals fluid system.Furthermore,we investigate the impact of MCG parameters and black hole charge on Joule-Thomson(J-T)expansion in the extended phase space.The J-T coefficient is examined to pinpoint the exact region experiencing cooling or heating,and the observation reveals that the presence of negative heat capacity results in the occurrence of a cooling process.The impact of MCG on the inversion curve of charged black holes exhibits a striking resemblance to that observed in most multi-dimensional black hole systems.In addition,it is worth noting that certain parameters exert a significant influence on the ratio T_(min)/Tc.For specific values of the MCG parameters,the ratio is consistent with the charged AdS black hole.The parametersγandβhave a non-negligible effect on the isenthalpic curve.展开更多
Based on the Einstein-Maxwell theory,the Joule-Thomson(J-T)expansion of charged dilatonic black holes(the solutions are neither flat nor AdS)in(n+1)-dimensional spacetime is studied herein.To this end,we analyze the e...Based on the Einstein-Maxwell theory,the Joule-Thomson(J-T)expansion of charged dilatonic black holes(the solutions are neither flat nor AdS)in(n+1)-dimensional spacetime is studied herein.To this end,we analyze the effects of the dimension n and dilaton fieldαon J-T expansion.An explicit expression for the J-T coefficient is derived,and consequently,a negative heat capacity is found to lead to a cooling process.In contrast to its effect on the dimension,the inversion curve decreases with charge Q at low pressures,whereas the opposite effect is observed at high pressures.We can observe that with an increase in the dimension n or parameter a,both the pressure cut-off point and the minimum inversion temperature T_(min)change.Moreover,we analyze the ratio T_(min)/T_(c)numerically and discover that the ratio is independent of charge;however,it depends on the dilaton field and dimension:for n=3 andα=0,the ratio is 1/2.The dilaton field is found to enhance the ratio.In addition,we identify the cooling-heating regions by investigating the inversion and isenthalpic curves,and the behavior of the minimum inversion mass M_(min)indicates that this cooling-heating transition may not occur under certain special conditions.展开更多
[目的]分析中国结直肠癌发病趋势,建立并比较预测模型在结直肠癌标化发病率中的应用。[方法]收集全球健康数据交换(Global Health Data Exchange,GHDx)数据库中1990—2019年中国结直肠癌发病率数据,利用Joinpoint线性回归模型分析计算...[目的]分析中国结直肠癌发病趋势,建立并比较预测模型在结直肠癌标化发病率中的应用。[方法]收集全球健康数据交换(Global Health Data Exchange,GHDx)数据库中1990—2019年中国结直肠癌发病率数据,利用Joinpoint线性回归模型分析计算结直肠癌发病率的年度变化百分比(annual percentage change,APC)。运用R4.1.2软件分别构建ARIMA模型、灰色模型以及XGBoost模型,比较三个模型拟合预测效果,选取最优模型对2020—2025年中国结直肠癌标化发病率进行预测。[结果]1990—2019年中国结直肠癌发病率以6.19%的速度稳步上升(标化发病率APC=3.66%,P<0.001),男性增速(发病率7.08%,标化发病率4.46%)高于女性(发病率4.93%,标化发病率2.50%)。构建的三个模型中,ARIMA(1,1,1)模型拟合预测效果优于GM(1,1)模型和XGBoost模型,相对误差(relative error,RE)在0.07%~2.26%之间,均方根误差(root mean square error,RMSE)、平均绝对误差(mean absolute error,MAE)和平均绝对百分比误差(mean absolute percentage error,MAPE)分别为0.286、0.231和1.134%。选取最优模型预测2020—2025年中国结直肠癌标化发病率,预测值依次为31.36/10万、32.05/10万、32.63/10万、33.14/10万、33.56/10万和33.93/10万。[结论]1990—2019年中国结直肠癌发病呈稳步上升趋势,ARIMA(1,1,1)模型在结直肠癌标化发病中具有良好的预测性能。展开更多
基金Supported by the Doctoral Foundation of Zunyi Normal University of China(BS[2022]07,QJJ-[2022]-314)the National Natural Science Foundation of China(12265007,12264061)partially was supported by the Long-Term Conceptual Development of a University of Hradec Královéfor 2023,issued by the Ministry of Education,Youth,and Sports of the Czech Republic。
文摘By considering the concept of a unified single fluid model,referred to as modified Chaplygin gas(MCG),which amalgamates dark energy and dark matter,we explore the thermodynamic characteristics of charged anti-de Sitter(AdS)black holes existing in an unconventional fluid accompanied by MCG.To accomplish this objective,we derive the equations of state by regarding the charge Q^(2) as a thermodynamic variable.The effects of MCG parameters on the critical thermodynamic quantities(ψ_(c),T_(c),Q_(c)^(2))are examined,followed by a detailed analysis of the Q^(2)-ψ diagram.To provide a clearer explanation of the phase transition,we present an analysis of the Gibbs free energy.It is important to note that if the Hawking temperature exceeds the critical temperature,a distinct pattern is observed known as swallowtail behavior.This indicates that the system undergoes a first-order phase transition from a smaller black hole to a larger one.The critical exponent of the system is found to be in complete agreement with that of the van der Waals fluid system.Furthermore,we investigate the impact of MCG parameters and black hole charge on Joule-Thomson(J-T)expansion in the extended phase space.The J-T coefficient is examined to pinpoint the exact region experiencing cooling or heating,and the observation reveals that the presence of negative heat capacity results in the occurrence of a cooling process.The impact of MCG on the inversion curve of charged black holes exhibits a striking resemblance to that observed in most multi-dimensional black hole systems.In addition,it is worth noting that certain parameters exert a significant influence on the ratio T_(min)/Tc.For specific values of the MCG parameters,the ratio is consistent with the charged AdS black hole.The parametersγandβhave a non-negligible effect on the isenthalpic curve.
基金Supported by the National Natural Science Foundation of China(11465006,11565009)the Doctoral Foundation of Zunyi Normal University of China(BS[2022]07,QJJ-[2022]-314)。
文摘Based on the Einstein-Maxwell theory,the Joule-Thomson(J-T)expansion of charged dilatonic black holes(the solutions are neither flat nor AdS)in(n+1)-dimensional spacetime is studied herein.To this end,we analyze the effects of the dimension n and dilaton fieldαon J-T expansion.An explicit expression for the J-T coefficient is derived,and consequently,a negative heat capacity is found to lead to a cooling process.In contrast to its effect on the dimension,the inversion curve decreases with charge Q at low pressures,whereas the opposite effect is observed at high pressures.We can observe that with an increase in the dimension n or parameter a,both the pressure cut-off point and the minimum inversion temperature T_(min)change.Moreover,we analyze the ratio T_(min)/T_(c)numerically and discover that the ratio is independent of charge;however,it depends on the dilaton field and dimension:for n=3 andα=0,the ratio is 1/2.The dilaton field is found to enhance the ratio.In addition,we identify the cooling-heating regions by investigating the inversion and isenthalpic curves,and the behavior of the minimum inversion mass M_(min)indicates that this cooling-heating transition may not occur under certain special conditions.
文摘[目的]分析中国结直肠癌发病趋势,建立并比较预测模型在结直肠癌标化发病率中的应用。[方法]收集全球健康数据交换(Global Health Data Exchange,GHDx)数据库中1990—2019年中国结直肠癌发病率数据,利用Joinpoint线性回归模型分析计算结直肠癌发病率的年度变化百分比(annual percentage change,APC)。运用R4.1.2软件分别构建ARIMA模型、灰色模型以及XGBoost模型,比较三个模型拟合预测效果,选取最优模型对2020—2025年中国结直肠癌标化发病率进行预测。[结果]1990—2019年中国结直肠癌发病率以6.19%的速度稳步上升(标化发病率APC=3.66%,P<0.001),男性增速(发病率7.08%,标化发病率4.46%)高于女性(发病率4.93%,标化发病率2.50%)。构建的三个模型中,ARIMA(1,1,1)模型拟合预测效果优于GM(1,1)模型和XGBoost模型,相对误差(relative error,RE)在0.07%~2.26%之间,均方根误差(root mean square error,RMSE)、平均绝对误差(mean absolute error,MAE)和平均绝对百分比误差(mean absolute percentage error,MAPE)分别为0.286、0.231和1.134%。选取最优模型预测2020—2025年中国结直肠癌标化发病率,预测值依次为31.36/10万、32.05/10万、32.63/10万、33.14/10万、33.56/10万和33.93/10万。[结论]1990—2019年中国结直肠癌发病呈稳步上升趋势,ARIMA(1,1,1)模型在结直肠癌标化发病中具有良好的预测性能。
