The effective diffusion coefficients in mine ventilation-flows had been obtained as 4 to 200 m^2/s by matching the measured concentration-time curves with the advec- tion-diffusion equation.The turbulent diffusion coe...The effective diffusion coefficients in mine ventilation-flows had been obtained as 4 to 200 m^2/s by matching the measured concentration-time curves with the advec- tion-diffusion equation.The turbulent diffusion coefficients in the simple airways have good agreement with the equation proposed by Taylor.However,for complex airways in operat- ing mines,the evaluated effective diffusion coefficients in the mines show higher values than that calculated by the Taylor's equation.A numerical simulation model using with movements of discrete particles dosed into ventilation flows has been developed to simu- late diffusion phenomena of gas or dust in mine airways.Numerical simulations had been conducted on distribution of tracers in single airways with ordinary profiles of mean velocity velocity fluctuations and Reynolds stress.As one of results,long band of diffused particles is obtained at the single airway of 600 m in length,and large effective diffusion coefficient is evaluated as 20 m^2/s.展开更多
In order to monitor dangerous areas in coal mines automatically,we propose to detect helmets from underground coal mine videos for detecting miners.This method can overcome the impact of similarity between the targets...In order to monitor dangerous areas in coal mines automatically,we propose to detect helmets from underground coal mine videos for detecting miners.This method can overcome the impact of similarity between the targets and their background.We constructed standard images of helmets,extracted four directional features,modeled the distribution of these features using a Gaussian function and separated local images of frames into helmet and non-helmet classes.Out experimental results show that this method can detect helmets effectively.The detection rate was 83.7%.展开更多
基金the National Natural Science Foundation of China(50375026)
文摘The effective diffusion coefficients in mine ventilation-flows had been obtained as 4 to 200 m^2/s by matching the measured concentration-time curves with the advec- tion-diffusion equation.The turbulent diffusion coefficients in the simple airways have good agreement with the equation proposed by Taylor.However,for complex airways in operat- ing mines,the evaluated effective diffusion coefficients in the mines show higher values than that calculated by the Taylor's equation.A numerical simulation model using with movements of discrete particles dosed into ventilation flows has been developed to simu- late diffusion phenomena of gas or dust in mine airways.Numerical simulations had been conducted on distribution of tracers in single airways with ordinary profiles of mean velocity velocity fluctuations and Reynolds stress.As one of results,long band of diffused particles is obtained at the single airway of 600 m in length,and large effective diffusion coefficient is evaluated as 20 m^2/s.
基金provided by the National High Technology Research and Development Program of China (No.2008AA062202)
文摘In order to monitor dangerous areas in coal mines automatically,we propose to detect helmets from underground coal mine videos for detecting miners.This method can overcome the impact of similarity between the targets and their background.We constructed standard images of helmets,extracted four directional features,modeled the distribution of these features using a Gaussian function and separated local images of frames into helmet and non-helmet classes.Out experimental results show that this method can detect helmets effectively.The detection rate was 83.7%.
