Dissolved organic carbon （DOC） is an important component for both carbon cycle and energy balance. The concentration, UV absorbance, and export flux of DOC in the natural environment dominate many important transpor...Dissolved organic carbon （DOC） is an important component for both carbon cycle and energy balance. The concentration, UV absorbance, and export flux of DOC in the natural environment dominate many important transport processes. To better understand the temporal and spatial variation of DOC, 7 sites along the Lower Dagu River were chosen to conduct a comprehensive measure- ment from March 2013 to February 2014. Specifically, water samples were collected from the Lower Dagu River between the 26th and 29th of every month during the experimental period. The DOC concentration （Cooc） and UV absorbance were analyzed using a total organic carbon analyzer and the ultraviolet-visible absorption spectrum, and the DOC export flux was estimated with a simple empirical model. The results showed that the CDoc of the Lower Dagu River varied from 1.32 to 12.56 mg/L, consistent with global rivers. The CDoc and UV absorbance showed significant spatial variation in the Dagu River during the experiential period because of the upstream natural processes and human activities in the watershed. The spatial variation is mainly due to dam or reservoir constructions, riverside ecological environment changes, and non-point source or wastewater discharge. The seasonal variation of CDoc was mainly related to the source of water DOC, river runoff, and temperature, and the UV absorbance and humification degree of DOC had no obvious differences among months （P〈 0.05）. UV absorbance was applied to test the CDOC in Lower Dagu River using wave lengths of 254 and 280 nm. The results revealed that the annual DOC export flux varied from 1.6 to 3.76x 105 g C^rn2/yr in a complete hydrological year, significantly lower than the global average. It is worth mentioning that the DOC export flux was mainly concentrated in summer （-90% of all-year flux in July and August）, since the runoff in the Dagu River took place frequently in summer. These observations implied environment change could bring the temporal-spatial variation of DOC and the e展开更多
A theoretical introduction of saturable absorber based on standing-wave saturation effects as a transient fiber Bragg grating （FBG） was presented. The central wavelength of the transient FBG was located in 2 μm. Th...A theoretical introduction of saturable absorber based on standing-wave saturation effects as a transient fiber Bragg grating （FBG） was presented. The central wavelength of the transient FBG was located in 2 μm. The factors affecting the bandwidth and the reflectivity of the transient FBG were analyzed. The linewidth and reflectiv- ity as the function of doped fiber length and doping concentration were correspondingly simulated by Matlab software. It was found that the larger the doping concentration and the fiber length were, the smaller the bandwidth was. These results suggest that the performance of the transient FBG can be optimized by choosing the appropriate length of doped fiber and the larger doping concentration, which can be used as a reference for the narrow-linewidth fiber laser around 2 μm.展开更多
From the large-scale equations of atmospheric motion, we investigated the long-time behaviour of atmospheric system forcing by exterior steady sources. Firstly, we established the fundamental functional space and oper...From the large-scale equations of atmospheric motion, we investigated the long-time behaviour of atmospheric system forcing by exterior steady sources. Firstly, we established the fundamental functional space and operator equations, and then demonstrated the existence and uniqueness theorems of solutions. Based on these results, the existence of the bounded global absorbing set and invariant set in it were discussed. Finally, the nonlinear adjustment process to exterior sources was revealed.展开更多
In the week August 20th-24th, the indexes of Shang-hai Stock and ShenzhenStock rocketed 9.69% and13.86% respectively, hit-ting their historical newhigh. It is surprised thatPBC announced on August22nd to increase both...In the week August 20th-24th, the indexes of Shang-hai Stock and ShenzhenStock rocketed 9.69% and13.86% respectively, hit-ting their historical newhigh. It is surprised thatPBC announced on August22nd to increase both thedeposit interest and loaninterest, the stock inves-tors passed it over. Sev-eral newly issued equitiesenter into stock market thatis absorbing over 200 thou-sand new private investorsto join in. RMB continues toappreciate with respect展开更多
文摘Dissolved organic carbon （DOC） is an important component for both carbon cycle and energy balance. The concentration, UV absorbance, and export flux of DOC in the natural environment dominate many important transport processes. To better understand the temporal and spatial variation of DOC, 7 sites along the Lower Dagu River were chosen to conduct a comprehensive measure- ment from March 2013 to February 2014. Specifically, water samples were collected from the Lower Dagu River between the 26th and 29th of every month during the experimental period. The DOC concentration （Cooc） and UV absorbance were analyzed using a total organic carbon analyzer and the ultraviolet-visible absorption spectrum, and the DOC export flux was estimated with a simple empirical model. The results showed that the CDoc of the Lower Dagu River varied from 1.32 to 12.56 mg/L, consistent with global rivers. The CDoc and UV absorbance showed significant spatial variation in the Dagu River during the experiential period because of the upstream natural processes and human activities in the watershed. The spatial variation is mainly due to dam or reservoir constructions, riverside ecological environment changes, and non-point source or wastewater discharge. The seasonal variation of CDoc was mainly related to the source of water DOC, river runoff, and temperature, and the UV absorbance and humification degree of DOC had no obvious differences among months （P〈 0.05）. UV absorbance was applied to test the CDOC in Lower Dagu River using wave lengths of 254 and 280 nm. The results revealed that the annual DOC export flux varied from 1.6 to 3.76x 105 g C^rn2/yr in a complete hydrological year, significantly lower than the global average. It is worth mentioning that the DOC export flux was mainly concentrated in summer （-90% of all-year flux in July and August）, since the runoff in the Dagu River took place frequently in summer. These observations implied environment change could bring the temporal-spatial variation of DOC and the e
基金This work was supported by the National Natural Science Foundation of China （Grant Nos. 61275083, 61290315）.
文摘A theoretical introduction of saturable absorber based on standing-wave saturation effects as a transient fiber Bragg grating （FBG） was presented. The central wavelength of the transient FBG was located in 2 μm. The factors affecting the bandwidth and the reflectivity of the transient FBG were analyzed. The linewidth and reflectiv- ity as the function of doped fiber length and doping concentration were correspondingly simulated by Matlab software. It was found that the larger the doping concentration and the fiber length were, the smaller the bandwidth was. These results suggest that the performance of the transient FBG can be optimized by choosing the appropriate length of doped fiber and the larger doping concentration, which can be used as a reference for the narrow-linewidth fiber laser around 2 μm.
文摘From the large-scale equations of atmospheric motion, we investigated the long-time behaviour of atmospheric system forcing by exterior steady sources. Firstly, we established the fundamental functional space and operator equations, and then demonstrated the existence and uniqueness theorems of solutions. Based on these results, the existence of the bounded global absorbing set and invariant set in it were discussed. Finally, the nonlinear adjustment process to exterior sources was revealed.
文摘In the week August 20th-24th, the indexes of Shang-hai Stock and ShenzhenStock rocketed 9.69% and13.86% respectively, hit-ting their historical newhigh. It is surprised thatPBC announced on August22nd to increase both thedeposit interest and loaninterest, the stock inves-tors passed it over. Sev-eral newly issued equitiesenter into stock market thatis absorbing over 200 thou-sand new private investorsto join in. RMB continues toappreciate with respect
