For the scientific management of farmland, it is significant to understand the spatio-temporal variability of soil organic matter and to study the influences of related factors. Using geostatistical theory, GIS spatia...For the scientific management of farmland, it is significant to understand the spatio-temporal variability of soil organic matter and to study the influences of related factors. Using geostatistical theory, GIS spatial analysis, trend analysis and a Geographically Weighted Regression （GWR） model, this study analyzed the response of soil organic matter to climate and socio-economic factors in central Heilongjiang Province during the past 25 years. Second soil survey data of China for 1979-1985, 2005 field sampling data, climate observations and socio-economic data for 1980-2005 were analyzed. First, soil organic matter in 2005 was spatially interpolated using the Co-Kriging method along with auxiliary data sets of soil type and pH. The spatio-temporal variability was then studied by comparison with the 1980s second soil census data. Next, the temporal trends in climate and socio-economic factors over the past 25 years were investigated. Finally, we examined the variation of the response of soil organic matter to climate and socio-economic factors using the GWR model spatially and temporally. The model showed that 53.82% area of the organic matter content remained constant and 29.39% has decreased during the past 25 years. The impact of precipitation on organic matter content is mainly negative, with increasing absolute values of the regression coefficient. The absolute value of regression coefficient of annual average temperature has decreased, and more areas are now under its negative effects. In addition, the areas of positive regression coefficient of annual sunshine hours have northward shifted, with the increasing absolute value of positive coefficient and decreasing absolute value of negative coefficient. The areas of positive regression coefficient of mechanized farming as a socio-economic factor have westward shifted, with the increasing absolute value of negative coefficient and decreasing absolute value of positive coefficient. The area of regions with the positive regression coefficient of irrigatio展开更多
The nonlinear physics dynamics of temporal dissipative solitons in a microcavity hinder them from attaining high power from pump lasers with a typical nonlinear energy conversion efficiency of less than 1%.Here,we exp...The nonlinear physics dynamics of temporal dissipative solitons in a microcavity hinder them from attaining high power from pump lasers with a typical nonlinear energy conversion efficiency of less than 1%.Here,we experimentally demonstrate a straightforward method for improving the output power of soliton combs using a silica microrod cavity with high coupling strength,large mode volume,and high-Q factor,resulting in a low-repetition-rate dissipative soliton(∼21 GHz)with an energy conversion efficiency exceeding 20%.Furthermore,by generating an∼105 GHz 5×FSR(free spectral range)soliton crystal comb in the microcavity,the energy conversion efficiency can be further increased up to 56%.展开更多
基金financed by the National Basic Research Program of China(2010CB951502)the National Natural Science Foundation of China(41101537,40930101,41201184 and 71203157)
文摘For the scientific management of farmland, it is significant to understand the spatio-temporal variability of soil organic matter and to study the influences of related factors. Using geostatistical theory, GIS spatial analysis, trend analysis and a Geographically Weighted Regression （GWR） model, this study analyzed the response of soil organic matter to climate and socio-economic factors in central Heilongjiang Province during the past 25 years. Second soil survey data of China for 1979-1985, 2005 field sampling data, climate observations and socio-economic data for 1980-2005 were analyzed. First, soil organic matter in 2005 was spatially interpolated using the Co-Kriging method along with auxiliary data sets of soil type and pH. The spatio-temporal variability was then studied by comparison with the 1980s second soil census data. Next, the temporal trends in climate and socio-economic factors over the past 25 years were investigated. Finally, we examined the variation of the response of soil organic matter to climate and socio-economic factors using the GWR model spatially and temporally. The model showed that 53.82% area of the organic matter content remained constant and 29.39% has decreased during the past 25 years. The impact of precipitation on organic matter content is mainly negative, with increasing absolute values of the regression coefficient. The absolute value of regression coefficient of annual average temperature has decreased, and more areas are now under its negative effects. In addition, the areas of positive regression coefficient of annual sunshine hours have northward shifted, with the increasing absolute value of positive coefficient and decreasing absolute value of negative coefficient. The areas of positive regression coefficient of mechanized farming as a socio-economic factor have westward shifted, with the increasing absolute value of negative coefficient and decreasing absolute value of positive coefficient. The area of regions with the positive regression coefficient of irrigatio
基金supported by the National Key Research and Development Program of China(Nos.2019YFB2203103 and 2021YFB-2800602)the National Natural Science Foundation of China(NSFC)(Nos.62001086 and 61705033)+1 种基金the Sichuan Science and Technology Program(No.2021YJ0095)the Fundamental Research Funds for the Central Universities(No.2021J003).
文摘The nonlinear physics dynamics of temporal dissipative solitons in a microcavity hinder them from attaining high power from pump lasers with a typical nonlinear energy conversion efficiency of less than 1%.Here,we experimentally demonstrate a straightforward method for improving the output power of soliton combs using a silica microrod cavity with high coupling strength,large mode volume,and high-Q factor,resulting in a low-repetition-rate dissipative soliton(∼21 GHz)with an energy conversion efficiency exceeding 20%.Furthermore,by generating an∼105 GHz 5×FSR(free spectral range)soliton crystal comb in the microcavity,the energy conversion efficiency can be further increased up to 56%.
