Delta function is an important function in mathematics and physics. In this paper, the Laplace transforms of δ(t)and δ(t-τ)have been discussed in detail. After the Laplace transform of δ(t)is analyzed, the author ...Delta function is an important function in mathematics and physics. In this paper, the Laplace transforms of δ(t)and δ(t-τ)have been discussed in detail. After the Laplace transform of δ(t)is analyzed, the author has found that three aspects should be taken into account, i.e. τ→0+, τ→0- andτ=0; and it is the same with the Laplace transform of δ(t-τ). Then the results of the Laplace transform of Delta function have been obtained in a rigorous and comprehensive sense.展开更多
The effects of human activities on the soil cover transformation in the eastern part of Kazakhstan were investigated during the period of 1956-2008.The results of the research for different soil types in Priaralye ind...The effects of human activities on the soil cover transformation in the eastern part of Kazakhstan were investigated during the period of 1956-2008.The results of the research for different soil types in Priaralye indicated that there was 643.3×103 hm2 solonchaks,accounting for 38.5 % of the total area（1670.5×10^3 hm^2） in 2008.Vast areas are occupied with dried lakeshore soil（311.1× 10^3 hm^2）,sandy soils（147.6×10^3 hm^2） and grey-brown desert soils and solonetzes（146.7×10^3 hm^2）.In 2001 the area of solonchak was 755×103 hm2 and decreased to 643.3×10^3 hm^2 in 2008,which due to the shrinkage of the Aral Sea,the areas of marsh and lakeshore solonchaks decreased with the increase of dried bottom of the Aral Sea.The level of soil cover transformation in the modern delta of the Syr-Darya River can be seen from the comparison of the results obtained from the different years in the study area.The area of solonchaks increased by 10×10^3 hm^2 and the area of alluvial-meadow salinizied soils increased by 17.9×10^3 hm^2 during the period of 1956-1969.It means that many non-salinizied soils were transformed into salinizied ones.Striking changes occurred in the structure of soil cover as a result of aridization.So,the researches in1969 significantly determined the areas of hydromorphic soils subjected to desertification（it was not fixed on the map before 1956）.Later,these soils were transformed into takyr-like soils.The area of takyr-like soils increased almost by 3 times for 34 years（from 1956 to 1990）.The long-term soil researches on soil cover transformation in Priaralye have shown that the tendencies of negative processes（salinization and deflation） are being kept and lead to further soil and eco-environment degradation in the region.展开更多
Regional economic integration can enhance the overall strength and competitiveness of the zone. The Yangtze River Delta,the Pearl River Delta and the Beijing-Tianjin-Hebei economic circles are the top three zones with...Regional economic integration can enhance the overall strength and competitiveness of the zone. The Yangtze River Delta,the Pearl River Delta and the Beijing-Tianjin-Hebei economic circles are the top three zones with economic viability in China. With the development of the economy,these three zones all follow the modern " tertiary,secondary,primary" industrial structure,while the corresponding employment population structure lags behind to a certain extent. Besides,the three major special economic zones are the regions receiving most of the migrant population in China. The inflow of labor has played a double-edged role in local economic and social development. Through systematically comparing the labor market changes in transformation and upgrading of the three major special economic zones,the reform experience could be obtained: urbanization can promote urban employment,industrial agglomeration can attract different employment types,and labor market system reform can enhance labor coordination in the zone.展开更多
基金Funded by by Natural Science Foundation Project of CQ CSTC (Grant No: cstc2012jjA50018)the Basic Research of Chongqing Municipal Education Commission (Grant No:KJ120613)
文摘Delta function is an important function in mathematics and physics. In this paper, the Laplace transforms of δ(t)and δ(t-τ)have been discussed in detail. After the Laplace transform of δ(t)is analyzed, the author has found that three aspects should be taken into account, i.e. τ→0+, τ→0- andτ=0; and it is the same with the Laplace transform of δ(t-τ). Then the results of the Laplace transform of Delta function have been obtained in a rigorous and comprehensive sense.
基金supported by the Department of Ecology in Kazakh Research Institute of Soil Science and Agrochemistry named after Uspanov,Almaty,Kazakhstan
文摘The effects of human activities on the soil cover transformation in the eastern part of Kazakhstan were investigated during the period of 1956-2008.The results of the research for different soil types in Priaralye indicated that there was 643.3×103 hm2 solonchaks,accounting for 38.5 % of the total area（1670.5×10^3 hm^2） in 2008.Vast areas are occupied with dried lakeshore soil（311.1× 10^3 hm^2）,sandy soils（147.6×10^3 hm^2） and grey-brown desert soils and solonetzes（146.7×10^3 hm^2）.In 2001 the area of solonchak was 755×103 hm2 and decreased to 643.3×10^3 hm^2 in 2008,which due to the shrinkage of the Aral Sea,the areas of marsh and lakeshore solonchaks decreased with the increase of dried bottom of the Aral Sea.The level of soil cover transformation in the modern delta of the Syr-Darya River can be seen from the comparison of the results obtained from the different years in the study area.The area of solonchaks increased by 10×10^3 hm^2 and the area of alluvial-meadow salinizied soils increased by 17.9×10^3 hm^2 during the period of 1956-1969.It means that many non-salinizied soils were transformed into salinizied ones.Striking changes occurred in the structure of soil cover as a result of aridization.So,the researches in1969 significantly determined the areas of hydromorphic soils subjected to desertification（it was not fixed on the map before 1956）.Later,these soils were transformed into takyr-like soils.The area of takyr-like soils increased almost by 3 times for 34 years（from 1956 to 1990）.The long-term soil researches on soil cover transformation in Priaralye have shown that the tendencies of negative processes（salinization and deflation） are being kept and lead to further soil and eco-environment degradation in the region.
文摘Regional economic integration can enhance the overall strength and competitiveness of the zone. The Yangtze River Delta,the Pearl River Delta and the Beijing-Tianjin-Hebei economic circles are the top three zones with economic viability in China. With the development of the economy,these three zones all follow the modern " tertiary,secondary,primary" industrial structure,while the corresponding employment population structure lags behind to a certain extent. Besides,the three major special economic zones are the regions receiving most of the migrant population in China. The inflow of labor has played a double-edged role in local economic and social development. Through systematically comparing the labor market changes in transformation and upgrading of the three major special economic zones,the reform experience could be obtained: urbanization can promote urban employment,industrial agglomeration can attract different employment types,and labor market system reform can enhance labor coordination in the zone.
