Pedogenic carbonates, found extensively in arid and semiarid regions, are important in revealing regional climatic and environmental changes as well as the carbon cycle. In addition, stable carbon and oxygen isotopic ...Pedogenic carbonates, found extensively in arid and semiarid regions, are important in revealing regional climatic and environmental changes as well as the carbon cycle. In addition, stable carbon and oxygen isotopic compositions of pedogenic carbonates have been used to rebuild paleoecology (biomass and vegetation) and to estimate paleotemperature and paleoprecipitation during past geological time. By utilizing the stable carbon and oxygen isotopic compositions (δ13C and (δ18O) of secondary nodules in Ustic Vertisols, this study looked into the climatic and environmental changes in the dry valleys of the Yuanmou Basin, Yunnan Province, in southwestern China. The results showed that during the early Holocene, a warm-humid or hot-humid climate existed in the Yuanmou Basin, but since then fluctuations in climate have occurred, with a dry climate prevailing. A highly significant correlation (r = 0.92, n = 9) between δ13C and δ18O values of carbonates illustrated that there had been a continual shifting between cold-humid and warm-dry climates in southwestern China including the Yuanmou Basin since the early Holocene.展开更多
The molten liquid discrete flow inside a packed bed is a typical transport phenomenon in the blast furnace. As for the reported mathematical models presenting the liquid discrete flow within the packed bed, there are ...The molten liquid discrete flow inside a packed bed is a typical transport phenomenon in the blast furnace. As for the reported mathematical models presenting the liquid discrete flow within the packed bed, there are some barriers for their application to an engineering scale-up, or some imperfections in model descriptions. To overcome these deficiencies, the effects of the packed bed on the liquid discrete flow have been divided into resistance action and dispersal action, and appropriate descriptions have been given for the two aetions, respectively. Consequently, a new mathematical model has been built to present the liquid discrete flow inside a coke bed in the blast furnace. The mathematical model can predict the distribution of liquid flux and the liquid flowing range inside the packed bed at any time. The prediction of this model accords well with the experimental data. The model will be much better for the simulation of the ironmaking process, compared with the existent model.展开更多
基金Project supported by the National Key Basic Research Support Foundation of China (No. G1998040800).
文摘Pedogenic carbonates, found extensively in arid and semiarid regions, are important in revealing regional climatic and environmental changes as well as the carbon cycle. In addition, stable carbon and oxygen isotopic compositions of pedogenic carbonates have been used to rebuild paleoecology (biomass and vegetation) and to estimate paleotemperature and paleoprecipitation during past geological time. By utilizing the stable carbon and oxygen isotopic compositions (δ13C and (δ18O) of secondary nodules in Ustic Vertisols, this study looked into the climatic and environmental changes in the dry valleys of the Yuanmou Basin, Yunnan Province, in southwestern China. The results showed that during the early Holocene, a warm-humid or hot-humid climate existed in the Yuanmou Basin, but since then fluctuations in climate have occurred, with a dry climate prevailing. A highly significant correlation (r = 0.92, n = 9) between δ13C and δ18O values of carbonates illustrated that there had been a continual shifting between cold-humid and warm-dry climates in southwestern China including the Yuanmou Basin since the early Holocene.
基金Item Sponsored by National Natural Science Foundation of China(50704040)
文摘The molten liquid discrete flow inside a packed bed is a typical transport phenomenon in the blast furnace. As for the reported mathematical models presenting the liquid discrete flow within the packed bed, there are some barriers for their application to an engineering scale-up, or some imperfections in model descriptions. To overcome these deficiencies, the effects of the packed bed on the liquid discrete flow have been divided into resistance action and dispersal action, and appropriate descriptions have been given for the two aetions, respectively. Consequently, a new mathematical model has been built to present the liquid discrete flow inside a coke bed in the blast furnace. The mathematical model can predict the distribution of liquid flux and the liquid flowing range inside the packed bed at any time. The prediction of this model accords well with the experimental data. The model will be much better for the simulation of the ironmaking process, compared with the existent model.
