The dependence of the maximum and average energies of protons, which were produced in the interaction of an intense laser pulse (similar to 1 x 10(16) W cm(-2), 65 fs) with hydrogen clusters in a gas jet backed up to 80 bar at liquid nitrogen temperature (similar to 80 K), on the backing pressure has been studied. The general trend of the proton energy dependence on the square of the average cluster radius, which is determined by a calibrated Rayleigh scattering measurement, is similar to that described by theory under the single size approximation. Calculations are made to fit the experimental results under a simplified model by taking into account both a log-normal cluster size distribution and the laser intensity attenuation in the interaction volume. A very good agreement between the experimental proton energy spectra and the calculations is obtained in the high- energy part of the proton energy distributions, but a discrepancy of the fits is revealed in the low-energy part at higher backing pressures which are associated with denser flows. A possible mechanism which would be responsible for this discrepancy is discussed. Finally, from the fits, a variation of the cluster size distributions was revealed to be dependent on the gas backing pressure as well as on the evolving time of the gas flow of clusters.
Gao W, Ma S, Reader C. An End-to-End Application System of AVS: AVS-IPTV in China, in Advances in Multimedia Information Processing - PCM 2007, 8th Pacific Rim Conference on Multimedia, Hong Kong, China, December 11-14, 2007, Proceedings.; 2007:50–57. 访问链接
Multi-year inventories of vehicular emissions at a high spatial resolution of 40 km×40 km were established in China using the GIS methodology for the period 1980–2005, based on provincial statistical data from yearbooks regarding vehicles and roads, and on the emission factors for each vehicle category in each province calculated by COPERT III program. Results showed that the emissions of CH4, CO, CO2, NMVOC, NOx, PM10, and SO2increased from 5, 1066, 19 893, 169, 174, 26, and 16 thousand tons in 1980 to 377, 36 197, 674 629, 5911, 4539, 983, and 484 thousand tons in 2005 at an annual average rate of 19%, 15%, 15%, 15%, 14%, 16%, and 15%, respectively. Statistical analysis of vehicular emissions and GDP showed that they were well positively correlated, which revealed that increase of pollutant emissions has been accompanying the growth of GDP. Spatial distribution of pollutant emissions was rather unbalanced: over three-quarters of the total emissions concentrated in developed regions of China's southeastern, northern and central areas covering only 35.2% of China's territory, while the remaining emissions were distributed over the southwestern, northwestern and northeastern regions covering as much as 64.8% of the territory. In 2005, the Beijing–Tianjin–Hebei region, the Yangtze River Delta, and the Pearl River Delta covering only 2.3%, 2.2%, and 1.9%, respectively, of the territory, generated about 10%, 19%, and 12%, respectively, of the total emissions. Since 1990, motorcycles have been the major contributors to the CH4, CO, NMVOC, and PM10emissions, due to the large population. Heavy-duty vans were the major contributors to the NOx and SO2 emissions because of high emission factors. Passenger cars contributed about one third of the emissions of each pollutant. Contributions of vehicle categories to emissions varied from province to province, due to the diversity of vehicle compositions among provinces.
