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 comb...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 ℃, 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 this paper,the complicated dynamics and multi-pulse homoclinic orbits of a two-degree-of-freedom parametrically excited nonlinear nano-oscillator with coupled cubic nonlinearities are studied.The damping,parametric...In this paper,the complicated dynamics and multi-pulse homoclinic orbits of a two-degree-of-freedom parametrically excited nonlinear nano-oscillator with coupled cubic nonlinearities are studied.The damping,parametrical excitation and the nonlinearities are regarded as weak.The averaged equation depicting the fast and slow dynamics is derived through the method of multiple scales.The dynamics near the resonance band is revealed by doing a singular perturbation analysis and combining the extended Melnikov method.We are able to determine the criterion for the existence of the multi-pulse homoclinic orbits which can form the Shilnikov orbits and give rise to chaos.At last,numerical results are also given to illustrate the nonlinear behaviors and chaotic motions in the nonlinear nano-oscillator.展开更多
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 ℃, 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 Nos.11290152,11072008 and 11372015)the Funding Project for Academic Human Resources Development in Institutions of Higher Learning under the Jurisdiction of Beijing Municipality(PHRIHLB)
文摘In this paper,the complicated dynamics and multi-pulse homoclinic orbits of a two-degree-of-freedom parametrically excited nonlinear nano-oscillator with coupled cubic nonlinearities are studied.The damping,parametrical excitation and the nonlinearities are regarded as weak.The averaged equation depicting the fast and slow dynamics is derived through the method of multiple scales.The dynamics near the resonance band is revealed by doing a singular perturbation analysis and combining the extended Melnikov method.We are able to determine the criterion for the existence of the multi-pulse homoclinic orbits which can form the Shilnikov orbits and give rise to chaos.At last,numerical results are also given to illustrate the nonlinear behaviors and chaotic motions in the nonlinear nano-oscillator.
