As air descends the intake shaft, its infrastructure, lining and the strata will emit heat during the night when the intake air is cool and, on the contrary, will absorb heat during the day when the temperature of the...As air descends the intake shaft, its infrastructure, lining and the strata will emit heat during the night when the intake air is cool and, on the contrary, will absorb heat during the day when the temperature of the air becomes greater than that of the strata. This cyclic phenomenon, also known as the "thermal damping effect" will continue throughout the year reducing the effect of surface air temperature variation. The objective of this paper is to quantify the thermal damping effect in vertical underground airways. A nonlinear autoregressive time series with external input(NARX) algorithm was used as a novel method to predict the dry-bulb temperature(Td) at the bottom of intake shafts as a function of surface air temperature. Analyses demonstrated that the artificial neural network(ANN) model could accurately predict the temperature at the bottom of a shaft. Furthermore, an attempt was made to quantify typical "damping coefficient" for both production and ventilation shafts through simple linear regression models. Comparisons between the collected climatic data and the regression-based predictions show that a simple linear regression model provides an acceptable accuracy when predicting the Tdat the bottom of intake shafts.展开更多
A three-factor three-level orthogonal test project has been designed based on the numerical simulation of a Jominy quenching process.Then the data scattering effects of thermal conductivity and enthalpy of tested stee...A three-factor three-level orthogonal test project has been designed based on the numerical simulation of a Jominy quenching process.Then the data scattering effects of thermal conductivity and enthalpy of tested steel,as well as the heat exchange coefficients of the cooling media,on the results have been studied.The results can be used as a reference for choosing the input thermal parameter in finite element simulation of quenching,and for evaluating the simulation results.展开更多
基金funded by National Institute for Occupational Safety and Health (NIOSH) (No. 2014-N-15795, 2014)
文摘As air descends the intake shaft, its infrastructure, lining and the strata will emit heat during the night when the intake air is cool and, on the contrary, will absorb heat during the day when the temperature of the air becomes greater than that of the strata. This cyclic phenomenon, also known as the "thermal damping effect" will continue throughout the year reducing the effect of surface air temperature variation. The objective of this paper is to quantify the thermal damping effect in vertical underground airways. A nonlinear autoregressive time series with external input(NARX) algorithm was used as a novel method to predict the dry-bulb temperature(Td) at the bottom of intake shafts as a function of surface air temperature. Analyses demonstrated that the artificial neural network(ANN) model could accurately predict the temperature at the bottom of a shaft. Furthermore, an attempt was made to quantify typical "damping coefficient" for both production and ventilation shafts through simple linear regression models. Comparisons between the collected climatic data and the regression-based predictions show that a simple linear regression model provides an acceptable accuracy when predicting the Tdat the bottom of intake shafts.
基金the Major Scientific Research Project of Shanghai Science & Technology Commission (No.08DZ1100302)the National Basic Research Program (973) of China (No.2011CB706600)
文摘A three-factor three-level orthogonal test project has been designed based on the numerical simulation of a Jominy quenching process.Then the data scattering effects of thermal conductivity and enthalpy of tested steel,as well as the heat exchange coefficients of the cooling media,on the results have been studied.The results can be used as a reference for choosing the input thermal parameter in finite element simulation of quenching,and for evaluating the simulation results.
