Based on the theory of nonlinear dynamic finite element,the control equation ofcoal and water jet was acquired in the coal breaking process under a water jet.The calculationmodel of coal breaking under a water jet was...Based on the theory of nonlinear dynamic finite element,the control equation ofcoal and water jet was acquired in the coal breaking process under a water jet.The calculationmodel of coal breaking under a water jet was established;the fluid-structure couplingof water jet and coal was implemented by penalty function and convection calculation.The dynamic process of coal breaking under a water jet was simulated and analyzed bycombining the united fracture criteria of the maximum tensile strain and the maximal shearstrain in the two cases of damage to coal and damage failure to coal.展开更多
To investigate the relationship between nonlinear parameters and spontaneous combustion tendency of sulfide ores,nine different sulfide ore samples were taken from a pyrite mine in China,and induced spontaneous combus...To investigate the relationship between nonlinear parameters and spontaneous combustion tendency of sulfide ores,nine different sulfide ore samples were taken from a pyrite mine in China,and induced spontaneous combustion experiment was carried out in the laboratory.Different stages of the induced spontaneous combustion process were studied by integrating wavelet technology and nonlinear dynamics theory.The results show that ignition points of all the ore samples are above 330 °C,indicating that sulfide ores of the pyrite mine are difficult to combust spontaneously under normal mining conditions.Spontaneous combustion process includes three stages: incubation stage,development stage and approaching stage.The average temperature rising rate of the three stages are 1.0 °C/min,2.0 °C/min and 4.2 °C/min,respectively.During the spontaneous combustion process,mean values of approximate entropy and correlation dimension increase at first,and then decrease in the following stage.The mean value of the maximum Lyapunov exponent increases with the passage of reaction time.In a whole,correlation among the three nonlinear parameters firstly weakens,then enhances,and the best correlation period is at approaching stage.As ignition point increases,the maximum Lyapunov exponent of approaching stage decreases.Therefore,combustible tendency of sulfide ores could be qualitatively evaluated based on the maximum Lyapunov exponent of this stage.展开更多
In recent years,significant progress has been made regarding theories of intraseasonal oscillations (ISOs) (also known as the Madden-Julian oscillation (MJO) in the tropics).This short review introduces the latest adv...In recent years,significant progress has been made regarding theories of intraseasonal oscillations (ISOs) (also known as the Madden-Julian oscillation (MJO) in the tropics).This short review introduces the latest advances in ISO theories with an emphasis particularly on theoretical paradigms involving nonlinear dynamics in the following aspects:(1) the basic ideas and limitations of the previous and current theories and hypotheses regarding the MJO,(2) the new multi-scale theory of the MJO based on the intraseasonal planetary equatorial synoptic dynamics (IPESD) framework,and (3) nonlinear dynamics of ISOs in the extratropics based on the resonant triads of Rossby-Haurwitz waves.展开更多
基金Supported by the National Basic Research Program of China(973 Program)(2005CB221504)the National Natural Science Foundation of China(50534080)the National Science and Technology Supporting Program of China(the 11th Five-Year Program)(2006BAK03B03)
文摘Based on the theory of nonlinear dynamic finite element,the control equation ofcoal and water jet was acquired in the coal breaking process under a water jet.The calculationmodel of coal breaking under a water jet was established;the fluid-structure couplingof water jet and coal was implemented by penalty function and convection calculation.The dynamic process of coal breaking under a water jet was simulated and analyzed bycombining the united fracture criteria of the maximum tensile strain and the maximal shearstrain in the two cases of damage to coal and damage failure to coal.
基金Supported by the State Key Development Program for Basic Research of China （2010CB22686） the National Natural Science Foundation of China （51174112, 51174272）
基金Projects(51304238,51534008)supported by the National Natural Science Foundation of ChinaProject(2015CX005)supported by Innovation Driven Plan of Central South University,China
文摘To investigate the relationship between nonlinear parameters and spontaneous combustion tendency of sulfide ores,nine different sulfide ore samples were taken from a pyrite mine in China,and induced spontaneous combustion experiment was carried out in the laboratory.Different stages of the induced spontaneous combustion process were studied by integrating wavelet technology and nonlinear dynamics theory.The results show that ignition points of all the ore samples are above 330 °C,indicating that sulfide ores of the pyrite mine are difficult to combust spontaneously under normal mining conditions.Spontaneous combustion process includes three stages: incubation stage,development stage and approaching stage.The average temperature rising rate of the three stages are 1.0 °C/min,2.0 °C/min and 4.2 °C/min,respectively.During the spontaneous combustion process,mean values of approximate entropy and correlation dimension increase at first,and then decrease in the following stage.The mean value of the maximum Lyapunov exponent increases with the passage of reaction time.In a whole,correlation among the three nonlinear parameters firstly weakens,then enhances,and the best correlation period is at approaching stage.As ignition point increases,the maximum Lyapunov exponent of approaching stage decreases.Therefore,combustible tendency of sulfide ores could be qualitatively evaluated based on the maximum Lyapunov exponent of this stage.
基金supported by the National Natural Science Foundation of China (Grant No. 40975028)
文摘In recent years,significant progress has been made regarding theories of intraseasonal oscillations (ISOs) (also known as the Madden-Julian oscillation (MJO) in the tropics).This short review introduces the latest advances in ISO theories with an emphasis particularly on theoretical paradigms involving nonlinear dynamics in the following aspects:(1) the basic ideas and limitations of the previous and current theories and hypotheses regarding the MJO,(2) the new multi-scale theory of the MJO based on the intraseasonal planetary equatorial synoptic dynamics (IPESD) framework,and (3) nonlinear dynamics of ISOs in the extratropics based on the resonant triads of Rossby-Haurwitz waves.
