It is important to determine the insulation thickness in the design of the buried hot oil pipelines.The economic thickness of the insulation layer not only meets the needs of the project but also maximizes the investm...It is important to determine the insulation thickness in the design of the buried hot oil pipelines.The economic thickness of the insulation layer not only meets the needs of the project but also maximizes the investment and environmental benefits.However,as a significant evaluation,the environmental factors haven’t been considered in the previous study.Considering this factor,the mathematical model of economic insulation thickness of the buried hot oil pipelines is built in this paper,which is solved by the golden section method while considering the costs of investment,operation,environment,the time value of money.The environmental cost is determined according to the pollutant discharge calculated through relating heat loss of the pipelines to the air emission while building the model.The results primarily showed that the most saving fuel is natural gas,followed by LPG,fuel oil,and coal.The fuel consumption for identical insulation thickness is in the order:coal,fuel oil,LPG,and natural gas.When taking the environmental costs into account,the thicker the economic insulation layer is,the higher cost it will be.Meanwhile,the more pollutant discharge,the thicker the economic insulation layer will be.展开更多
Large-scale patterns of species richness have gained much attention in recent years; however, the factors that drive high species richness are still controversial in local regions, especially in highly diversified mon...Large-scale patterns of species richness have gained much attention in recent years; however, the factors that drive high species richness are still controversial in local regions, especially in highly diversified montane regions. The Qinghai-Tibetan Plateau （QTP） and the surrounding mountains are biodiversity hot spots due to a high number of endemic montane species. Here, we explored the fac- tors underlying this high level of diversity by studying the relationship between species richness and environmental variables. The richness patterns of 758 resident bird species were summarized at the scale of 1°× 1° grid cell at different taxonomic levels （order, family, genus, and species） and in differ- ent taxonomic groups （Passeriformes, Galliformes, Falconiformes, and Columbiformes）. These rich- ness patterns were subsequently analyzed against habitat heterogeneity （topographical heterogen- eity and land cover）, temperature amplitude （annual temperature, annual precipitation, precipitation seasonality, and temperature seasonality） and a vegetation index （net primary productivity）. Our re- sults showed that the highest richness was found in the southeastern part of the QTP, the eastern Himalayas. The lowest richness was observed in the central plateau of the QTP. Topographical het- erogeneity and temperature amplitude are the primary factors that explain overall patterns of species richness in the QTP, although the specific effect of each environmental variable varies between the different taxonomic groups depending on their own evolutionary histories and ecological require- ments. High species richness in the southeastern QTP is mostly due to highly diversified habitat types and temperature zones along elevation gradients, whereas the low species richness in the cen- tral plateau of the QTP may be due to environmental and energetic constraints, as the central plateau is harsh environment.展开更多
基金funded by the National Natural Science Foundation of China(NO.51704236)the Graduate Innovation and Practice Ability Development Program of Xi’an Shiyou University(NO.YCS19113037).
文摘It is important to determine the insulation thickness in the design of the buried hot oil pipelines.The economic thickness of the insulation layer not only meets the needs of the project but also maximizes the investment and environmental benefits.However,as a significant evaluation,the environmental factors haven’t been considered in the previous study.Considering this factor,the mathematical model of economic insulation thickness of the buried hot oil pipelines is built in this paper,which is solved by the golden section method while considering the costs of investment,operation,environment,the time value of money.The environmental cost is determined according to the pollutant discharge calculated through relating heat loss of the pipelines to the air emission while building the model.The results primarily showed that the most saving fuel is natural gas,followed by LPG,fuel oil,and coal.The fuel consumption for identical insulation thickness is in the order:coal,fuel oil,LPG,and natural gas.When taking the environmental costs into account,the thicker the economic insulation layer is,the higher cost it will be.Meanwhile,the more pollutant discharge,the thicker the economic insulation layer will be.
基金This study was supported by the Strategic Priority Research Program of the Chinese Academy of Sciences （XDA05080703 and XDB13020300）, the State Key Program of National Science Foundation of China （31330073 31471990）, the Knowledge Innovation Program of the Chinese Academy of Sciences （KSCX2-EW-Z-5）, the Chinese Science Database （XXH12504-1-12） and Science and Technology Foundation Project （2014FY210200）.
文摘Large-scale patterns of species richness have gained much attention in recent years; however, the factors that drive high species richness are still controversial in local regions, especially in highly diversified montane regions. The Qinghai-Tibetan Plateau （QTP） and the surrounding mountains are biodiversity hot spots due to a high number of endemic montane species. Here, we explored the fac- tors underlying this high level of diversity by studying the relationship between species richness and environmental variables. The richness patterns of 758 resident bird species were summarized at the scale of 1°× 1° grid cell at different taxonomic levels （order, family, genus, and species） and in differ- ent taxonomic groups （Passeriformes, Galliformes, Falconiformes, and Columbiformes）. These rich- ness patterns were subsequently analyzed against habitat heterogeneity （topographical heterogen- eity and land cover）, temperature amplitude （annual temperature, annual precipitation, precipitation seasonality, and temperature seasonality） and a vegetation index （net primary productivity）. Our re- sults showed that the highest richness was found in the southeastern part of the QTP, the eastern Himalayas. The lowest richness was observed in the central plateau of the QTP. Topographical het- erogeneity and temperature amplitude are the primary factors that explain overall patterns of species richness in the QTP, although the specific effect of each environmental variable varies between the different taxonomic groups depending on their own evolutionary histories and ecological require- ments. High species richness in the southeastern QTP is mostly due to highly diversified habitat types and temperature zones along elevation gradients, whereas the low species richness in the cen- tral plateau of the QTP may be due to environmental and energetic constraints, as the central plateau is harsh environment.
