Complex hydrocultural conditions in the estuary affect the migration and transformation of mercury.Using two voyages in July and October 2018,Dissolved Gaseous Mercury(DGM)and Reactive Mercury(RHg)were determined to e...Complex hydrocultural conditions in the estuary affect the migration and transformation of mercury.Using two voyages in July and October 2018,Dissolved Gaseous Mercury(DGM)and Reactive Mercury(RHg)were determined to explore the source,transformation and influence of DGM content in the adjacent waters of Yangtze River Estuary in summer and autumn.The results showed the contents of DGM and RHg in summer were higher than those in autumn,and both of them were higher than those in open sea.In summer and autumn,the Yangtze River brought a higher concentration of DGM,and different flow direction and runoff resulted in differences in the high value region of the surface.The emergence of low-oxygen zones in summer was conducive to the production of DGM.In autumn,windy weather allowed seawater disturbances to promote the release of mercury from the underlying sediments,especially in shallow sea in northwest.RHg showed a higher concentration in the offshore than in the open sea in summer,but there was no such trend in autumn,reflecting the influence of less runoff input.DGM is the main product of RHg reduction,and there was a significant positive correlation between DGM and RHg in summer(r=0.356,P<0.05),while the correlation between DGM and RHg was not significant in autumn due to the influence of light intensity,wind speed and nutrients.The exchange flux of mercury in the adjacent waters of the Yangtze River Estuary was higher than that in the open sea.There was no significant difference of the release flux of mercury in summer and autumn.This article highlighted that the input of mercury from the Yangtze River runoff promotes the release of mercury in seawater,and the hypoxic zone caused by eutrophication is conducive to the production of DGM.展开更多
Shannon channel capacity theorem poses highest bit-rate of error free transmission over additive white Gaussian noise channel.In addition,he proved that there exists channel code that can theoretically achieve the cha...Shannon channel capacity theorem poses highest bit-rate of error free transmission over additive white Gaussian noise channel.In addition,he proved that there exists channel code that can theoretically achieve the channel capacity.Indeed fortunately,the latter researchers found some practical channel codes approaching the channel capacity with insignificant losses of spectral efficiency under ignorable bit error rate(BER).The authors note,in general,that bits of the channel codes are not independent of each other in code space.Further,we note that the modulated symbols are not independent among them,as well,in Euclidean Space.By exploiting a usage of the dependencies jointly to signal design,we can transmit two independent signal streams through an additive white Gaussian channel and separate them in Euclidean space at the receiver.The capacity of this approach is found larger than that of Shannon capacity in the same channel assumptions.The numerical results confirm the theoretical procedures.展开更多
Drought is the uppermost natural disaster in the Hebei Plain,which during the past 20 years showed a trend of frequency increasing,range extension,longer duration and severer damage. In the Hebei Plain,as a major grai...Drought is the uppermost natural disaster in the Hebei Plain,which during the past 20 years showed a trend of frequency increasing,range extension,longer duration and severer damage. In the Hebei Plain,as a major grain producing area,the agricultural drought emergency relief can only rely on groundwater exploitation. Thus the work to conduct evaluation of groundwater supply capacity for agricultural drought emergency relief of Hebei Plain is of great significance for disaster prevention and relief. In this paper,with the method of analytic hierarchy process,the evaluation index system with reference to 3 aspects and 7 indexes(the former including groundwater resources,groundwater exploitation technical conditions and water supply facilities) and the Arc GIS Desktop Arc MAP software,the work to assess the shallow groundwater supply capacity for agricultural drought emergency relief in the Hebei Plain was carried out.展开更多
基金the National Natural Science Foundation of China(Nos.41506128,40806045 and 41749903)the Oceanographic Research Vessel Sharing Plan(No.NORC2018-06-25)。
文摘Complex hydrocultural conditions in the estuary affect the migration and transformation of mercury.Using two voyages in July and October 2018,Dissolved Gaseous Mercury(DGM)and Reactive Mercury(RHg)were determined to explore the source,transformation and influence of DGM content in the adjacent waters of Yangtze River Estuary in summer and autumn.The results showed the contents of DGM and RHg in summer were higher than those in autumn,and both of them were higher than those in open sea.In summer and autumn,the Yangtze River brought a higher concentration of DGM,and different flow direction and runoff resulted in differences in the high value region of the surface.The emergence of low-oxygen zones in summer was conducive to the production of DGM.In autumn,windy weather allowed seawater disturbances to promote the release of mercury from the underlying sediments,especially in shallow sea in northwest.RHg showed a higher concentration in the offshore than in the open sea in summer,but there was no such trend in autumn,reflecting the influence of less runoff input.DGM is the main product of RHg reduction,and there was a significant positive correlation between DGM and RHg in summer(r=0.356,P<0.05),while the correlation between DGM and RHg was not significant in autumn due to the influence of light intensity,wind speed and nutrients.The exchange flux of mercury in the adjacent waters of the Yangtze River Estuary was higher than that in the open sea.There was no significant difference of the release flux of mercury in summer and autumn.This article highlighted that the input of mercury from the Yangtze River runoff promotes the release of mercury in seawater,and the hypoxic zone caused by eutrophication is conducive to the production of DGM.
基金supported by two Programs of National Natural Science Foundation of China(No.61271203 and No.61531004)
文摘Shannon channel capacity theorem poses highest bit-rate of error free transmission over additive white Gaussian noise channel.In addition,he proved that there exists channel code that can theoretically achieve the channel capacity.Indeed fortunately,the latter researchers found some practical channel codes approaching the channel capacity with insignificant losses of spectral efficiency under ignorable bit error rate(BER).The authors note,in general,that bits of the channel codes are not independent of each other in code space.Further,we note that the modulated symbols are not independent among them,as well,in Euclidean Space.By exploiting a usage of the dependencies jointly to signal design,we can transmit two independent signal streams through an additive white Gaussian channel and separate them in Euclidean space at the receiver.The capacity of this approach is found larger than that of Shannon capacity in the same channel assumptions.The numerical results confirm the theoretical procedures.
文摘Drought is the uppermost natural disaster in the Hebei Plain,which during the past 20 years showed a trend of frequency increasing,range extension,longer duration and severer damage. In the Hebei Plain,as a major grain producing area,the agricultural drought emergency relief can only rely on groundwater exploitation. Thus the work to conduct evaluation of groundwater supply capacity for agricultural drought emergency relief of Hebei Plain is of great significance for disaster prevention and relief. In this paper,with the method of analytic hierarchy process,the evaluation index system with reference to 3 aspects and 7 indexes(the former including groundwater resources,groundwater exploitation technical conditions and water supply facilities) and the Arc GIS Desktop Arc MAP software,the work to assess the shallow groundwater supply capacity for agricultural drought emergency relief in the Hebei Plain was carried out.
