Ultraviolet （UV） aging is one of the main factors which cause premature damage of asphalt pavements in the Tibetan Plateau, China. According to the measured levels of UV radiation, aging tests of styrene-butadiene r...Ultraviolet （UV） aging is one of the main factors which cause premature damage of asphalt pavements in the Tibetan Plateau, China. According to the measured levels of UV radiation, aging tests of styrene-butadiene rubber （SBR） asphalts with different contents of three anti-UV-aging agents including nano-TiO2, CeO2 and carbon black are performed. Common indices, which include retained penetration after thin film oven tests （TFOT） and softening point, and strategic highway research program （SHRP） indices of aged asphalts are evaluated. Infrared absorption spectral analysis is performed on asphalt specimens with 0. 8% carbon black which have been aged for different aging times （500, 1000 and 1 500 h）. By grey incidence analysis, the optimal contents of anti-UV-aging agents are determined. The results show that TiO2 and CeO2 are not only good UV absorbing or shielding agents, but also strong oxidants. Carbon black is a good anti-UV-aging agent, and its optimal content is about 0. 8% of asphalt weight. UV aging of asphalt mainly occurs in the early stages of aging. The longer the aging time, the more severe the aging of asphalt.展开更多
A fast algorithm based on the grayscale distribution of infrared target and the weighted kernel function was proposed for the moving target detection(MTD) in dynamic scene of image series. This algorithm is used to de...A fast algorithm based on the grayscale distribution of infrared target and the weighted kernel function was proposed for the moving target detection(MTD) in dynamic scene of image series. This algorithm is used to deal with issues like the large computational complexity, the fluctuation of grayscale, and the noise in infrared images. Four characteristic points were selected by analyzing the grayscale distribution in infrared image, of which the series was quickly matched with an affine transformation model. The image was then divided into 32×32 squares and the gray-weighted kernel(GWK) for each square was calculated. At last, the MTD was carried out according to the variation of the four GWKs. The results indicate that the MTD can be achieved in real time using the algorithm with the fluctuations of grayscale and noise can be effectively suppressed. The detection probability is greater than 90% with the false alarm rate lower than 5% when the calculation time is less than 40 ms.展开更多
Flotation tests, contact angle measurements, infrared spectrum analyses, X-ray analyses and computer simulation were carried out in order to study the activation mechanism of lime-depressed pyrite with oxalic acid. Th...Flotation tests, contact angle measurements, infrared spectrum analyses, X-ray analyses and computer simulation were carried out in order to study the activation mechanism of lime-depressed pyrite with oxalic acid. The results show that the oxalic acid effectively eliminated the hydrophilic calcium film from the surface of pyrite. Therefore, the efficiency of pyrite flotation was also activated. The results indicate that after reacting with hydrophobic insoluble remainders on the surface of pyrite, oxalic acid can pro- duce hydrophilic compounds, such as CaC03, Ca（OH）2 and Fe（OH）3. As a consequence, a flesh pyrite layer was exposed and its flotation activated.展开更多
文摘Ultraviolet （UV） aging is one of the main factors which cause premature damage of asphalt pavements in the Tibetan Plateau, China. According to the measured levels of UV radiation, aging tests of styrene-butadiene rubber （SBR） asphalts with different contents of three anti-UV-aging agents including nano-TiO2, CeO2 and carbon black are performed. Common indices, which include retained penetration after thin film oven tests （TFOT） and softening point, and strategic highway research program （SHRP） indices of aged asphalts are evaluated. Infrared absorption spectral analysis is performed on asphalt specimens with 0. 8% carbon black which have been aged for different aging times （500, 1000 and 1 500 h）. By grey incidence analysis, the optimal contents of anti-UV-aging agents are determined. The results show that TiO2 and CeO2 are not only good UV absorbing or shielding agents, but also strong oxidants. Carbon black is a good anti-UV-aging agent, and its optimal content is about 0. 8% of asphalt weight. UV aging of asphalt mainly occurs in the early stages of aging. The longer the aging time, the more severe the aging of asphalt.
基金Project(61101185)supported by the National Natural Science Foundation of China
文摘A fast algorithm based on the grayscale distribution of infrared target and the weighted kernel function was proposed for the moving target detection(MTD) in dynamic scene of image series. This algorithm is used to deal with issues like the large computational complexity, the fluctuation of grayscale, and the noise in infrared images. Four characteristic points were selected by analyzing the grayscale distribution in infrared image, of which the series was quickly matched with an affine transformation model. The image was then divided into 32×32 squares and the gray-weighted kernel(GWK) for each square was calculated. At last, the MTD was carried out according to the variation of the four GWKs. The results indicate that the MTD can be achieved in real time using the algorithm with the fluctuations of grayscale and noise can be effectively suppressed. The detection probability is greater than 90% with the false alarm rate lower than 5% when the calculation time is less than 40 ms.
基金the financial support from the Key Projects in the National Science & Technology Pillar Program for the Eleventh Five-Year Plan (No. 2006BAB02A06)
文摘Flotation tests, contact angle measurements, infrared spectrum analyses, X-ray analyses and computer simulation were carried out in order to study the activation mechanism of lime-depressed pyrite with oxalic acid. The results show that the oxalic acid effectively eliminated the hydrophilic calcium film from the surface of pyrite. Therefore, the efficiency of pyrite flotation was also activated. The results indicate that after reacting with hydrophobic insoluble remainders on the surface of pyrite, oxalic acid can pro- duce hydrophilic compounds, such as CaC03, Ca（OH）2 and Fe（OH）3. As a consequence, a flesh pyrite layer was exposed and its flotation activated.
