A new way to improve the tunnel fire protection by using flame-retarded porous asphalt pavement containing ATH powders was introduced. Based on the miniature burning test designed and conducted, the burning time and t...A new way to improve the tunnel fire protection by using flame-retarded porous asphalt pavement containing ATH powders was introduced. Based on the miniature burning test designed and conducted, the burning time and temperature of porous asphalt （PA） and flame-retarded porous asphalt （FRPA） were studied comparing with cement concrete pavement, dense-graded lIMA and SMA. Results of burning test and pavement performance test indicate that FRPA is appropriate and suitable as the pavement material of highway tunnel.展开更多
There are high costs in paving services in the Brazilian Amazon region, mainly due to the lack of coarse aggregate--pebble or crushed stone---in addition to the elevated rainfall and the high geographic expanse of the...There are high costs in paving services in the Brazilian Amazon region, mainly due to the lack of coarse aggregate--pebble or crushed stone---in addition to the elevated rainfall and the high geographic expanse of the region. The natural coarse aggregate often used in that region is extracted from the riverbeds a distance no less than 500 km from the major cities. In search of a technical, economic and environmental alternative to work around the problem, using an unconventional material that could replace the pebble or crushed stone, a study was carded out on natural clay, considered an abundant mineral resource, especially in the Amazon Basin. A manual mill was used for this purpose, consisting of four square metal nozzles of dimensions 12.7 mm, 9.5 mm, 4.8 mm and 2.0 mm, used for moulding the wet ribbon clay. After that, firing was carried out at temperatures of 780℃, 850℃, 950℃, 1,050 ℃ to 1,150℃ A comparative analysis between conventional hot mixed asphalt--using pebble as coarse aggregate--and that employing synthetic aggregate was made. In a general way, hot mixed asphalt using synthetic aggregate showed excellent results of physical and mechanical properties, in relation to the conventional mixture, mainly at higher temperature of aggregate calcination.展开更多
Organic dust flames deal with a field of science in which many complicated phenomena like pyrolysis or devolatization of solid particles and combustion of volatile particles take place. One-dimensional flame propagati...Organic dust flames deal with a field of science in which many complicated phenomena like pyrolysis or devolatization of solid particles and combustion of volatile particles take place. One-dimensional flame propagation in cloud of fuel mixture is analyzed in which flame structure is divided into three zones. The first zone is preheat zone in which rate of the chemical reaction is small and transfer phenomena play significant role in temperature and mass distributions. In this model, it is assumed that particles pyrolyze first to yield a gaseous fuel mixture. The second zone is reaction zone where convection and vaporization rates of the particles are small. The third zone is convection zone where diffusive terms are negligible in comparison of other terms. Non-zero Biot number is used in order to study effect of particles thermal resistance on flame characteristics. Also, effect of particle size on combustion of micro organic dust is investigated. According to obtained results, it is understood that both flame temperature and burning velocity decrease with rise in the Biot number and particle size.展开更多
In this article,two concepts of temperature,i.e.,Bums temperature for relaxor ferroelectrics andquantum temperature scale for quantum paraelectrics,are reviewed briefly.Since both tem-peratures describe the deviation ...In this article,two concepts of temperature,i.e.,Bums temperature for relaxor ferroelectrics andquantum temperature scale for quantum paraelectrics,are reviewed briefly.Since both tem-peratures describe the deviation of the dielectric constant from Curie-Weiss law,their re-lationship is discussed.Finally the concept of quantum temperature scale is extended todemonstrate the evolution process of quantum paraelectric behavior to relaxor ferroelectricbehavior.展开更多
基金Hi-tech Research and Development Program of China (863 Program of China) (No.2006AA11Z117)
文摘A new way to improve the tunnel fire protection by using flame-retarded porous asphalt pavement containing ATH powders was introduced. Based on the miniature burning test designed and conducted, the burning time and temperature of porous asphalt （PA） and flame-retarded porous asphalt （FRPA） were studied comparing with cement concrete pavement, dense-graded lIMA and SMA. Results of burning test and pavement performance test indicate that FRPA is appropriate and suitable as the pavement material of highway tunnel.
文摘There are high costs in paving services in the Brazilian Amazon region, mainly due to the lack of coarse aggregate--pebble or crushed stone---in addition to the elevated rainfall and the high geographic expanse of the region. The natural coarse aggregate often used in that region is extracted from the riverbeds a distance no less than 500 km from the major cities. In search of a technical, economic and environmental alternative to work around the problem, using an unconventional material that could replace the pebble or crushed stone, a study was carded out on natural clay, considered an abundant mineral resource, especially in the Amazon Basin. A manual mill was used for this purpose, consisting of four square metal nozzles of dimensions 12.7 mm, 9.5 mm, 4.8 mm and 2.0 mm, used for moulding the wet ribbon clay. After that, firing was carried out at temperatures of 780℃, 850℃, 950℃, 1,050 ℃ to 1,150℃ A comparative analysis between conventional hot mixed asphalt--using pebble as coarse aggregate--and that employing synthetic aggregate was made. In a general way, hot mixed asphalt using synthetic aggregate showed excellent results of physical and mechanical properties, in relation to the conventional mixture, mainly at higher temperature of aggregate calcination.
文摘Organic dust flames deal with a field of science in which many complicated phenomena like pyrolysis or devolatization of solid particles and combustion of volatile particles take place. One-dimensional flame propagation in cloud of fuel mixture is analyzed in which flame structure is divided into three zones. The first zone is preheat zone in which rate of the chemical reaction is small and transfer phenomena play significant role in temperature and mass distributions. In this model, it is assumed that particles pyrolyze first to yield a gaseous fuel mixture. The second zone is reaction zone where convection and vaporization rates of the particles are small. The third zone is convection zone where diffusive terms are negligible in comparison of other terms. Non-zero Biot number is used in order to study effect of particles thermal resistance on flame characteristics. Also, effect of particle size on combustion of micro organic dust is investigated. According to obtained results, it is understood that both flame temperature and burning velocity decrease with rise in the Biot number and particle size.
基金Natural Science Fund of China under grant No.50702030.
文摘In this article,two concepts of temperature,i.e.,Bums temperature for relaxor ferroelectrics andquantum temperature scale for quantum paraelectrics,are reviewed briefly.Since both tem-peratures describe the deviation of the dielectric constant from Curie-Weiss law,their re-lationship is discussed.Finally the concept of quantum temperature scale is extended todemonstrate the evolution process of quantum paraelectric behavior to relaxor ferroelectricbehavior.
