Surface textures had long been recognized as primary factors to provide the skid resistance on pavements; however, no measurement of skid resistance on pervious concrete pavement with various surface texture parameter...Surface textures had long been recognized as primary factors to provide the skid resistance on pavements; however, no measurement of skid resistance on pervious concrete pavement with various surface texture parameters had been made. Fractal geometry was introduced in the present work to accurately simulate transect contour curves of pervious concrete specimens through fractal interpolation. It is proved that its fractal dimension (D) can be adopted to measure the skid resistance on pervious concrete pavement, overcoming the shortcomings of both macrotexture depth (DT ) and British portable pendulum number (NBP). Combined with Fujikawa-Koike tire/road contact model, the optimization method of all surface textures was recommended for designing and constructing excellently skid-resistant and noise-absorptive pervious concrete pavement. In addition, evaluating of the abrasion process and attenuation of the surface textures on concrete pavement slabs was also the focus of this work based on accelerated abrasion test. Results show that the surface textures on pervious concrete pavement slabs is extremely durable, compared to those on conventional grooved or exposed aggregate concrete pavement slabs.展开更多
Roughening the surfaces of zirconium alloy tubes by glass-bead peening has been shown to increase the CHF （critical heat flux） in pool-boiling of water. The increase in CHF attributed to surface roughening effect ha...Roughening the surfaces of zirconium alloy tubes by glass-bead peening has been shown to increase the CHF （critical heat flux） in pool-boiling of water. The increase in CHF attributed to surface roughening effect has been measured in pool-boiling experiments using small-diameter zirconium alloy tubes that have been glass-peened with different bead sizes, intensity and coverage. The CHF was found to correlate with the fractal roughness measured on the metal surfaces. In this study, the nucleate pool-boiling characteristics of a large diameter Zircaloy-2 CANDU~ calandria tube （outer diameter -132 mm） with a glass-peened outside surface were tested in a pool of water near saturation. The primary objective was to measure the wall temperature and heat flux in order to develop a representative nucleate pool-boiling curve for large-diameter tubes with a glass-peened outside surface. By comparing the experimental results with models （e.g., Rohsenow correlation）, a modified boiling correlation has been developed for a glass-peened surface of calandria tubes that includes a surface roughness parameter.展开更多
基金Project(kfj080205) supported by Key Laboratory of Road Structure and Material of Ministry of Transport of Changsha, China
文摘Surface textures had long been recognized as primary factors to provide the skid resistance on pavements; however, no measurement of skid resistance on pervious concrete pavement with various surface texture parameters had been made. Fractal geometry was introduced in the present work to accurately simulate transect contour curves of pervious concrete specimens through fractal interpolation. It is proved that its fractal dimension (D) can be adopted to measure the skid resistance on pervious concrete pavement, overcoming the shortcomings of both macrotexture depth (DT ) and British portable pendulum number (NBP). Combined with Fujikawa-Koike tire/road contact model, the optimization method of all surface textures was recommended for designing and constructing excellently skid-resistant and noise-absorptive pervious concrete pavement. In addition, evaluating of the abrasion process and attenuation of the surface textures on concrete pavement slabs was also the focus of this work based on accelerated abrasion test. Results show that the surface textures on pervious concrete pavement slabs is extremely durable, compared to those on conventional grooved or exposed aggregate concrete pavement slabs.
文摘Roughening the surfaces of zirconium alloy tubes by glass-bead peening has been shown to increase the CHF （critical heat flux） in pool-boiling of water. The increase in CHF attributed to surface roughening effect has been measured in pool-boiling experiments using small-diameter zirconium alloy tubes that have been glass-peened with different bead sizes, intensity and coverage. The CHF was found to correlate with the fractal roughness measured on the metal surfaces. In this study, the nucleate pool-boiling characteristics of a large diameter Zircaloy-2 CANDU~ calandria tube （outer diameter -132 mm） with a glass-peened outside surface were tested in a pool of water near saturation. The primary objective was to measure the wall temperature and heat flux in order to develop a representative nucleate pool-boiling curve for large-diameter tubes with a glass-peened outside surface. By comparing the experimental results with models （e.g., Rohsenow correlation）, a modified boiling correlation has been developed for a glass-peened surface of calandria tubes that includes a surface roughness parameter.
