This paper considers the distribution of technogenic 137Cs and naturally occurring radionuclides:238 U,232 Th and40 R concentrations in soils and 137Cs in atmospheric dry depositions by altitudinal belts of the Aragat...This paper considers the distribution of technogenic 137Cs and naturally occurring radionuclides:238 U,232 Th and40 R concentrations in soils and 137Cs in atmospheric dry depositions by altitudinal belts of the Aragats mountain massif,Republic of Armenia.Undisturbed soil samples were collected at altitudes from 1000 to 3200 m.For the determination of geochemical variability,two soil sampling campaigns were undertaken.Atmospheric dry depositions were sampled from five stations at1100-3200 m collected onto organic fiber filters between June and December 2016.137Cs activity was measured using a high-purity Germanium detector coupled to a multichannel analyzer(Canberra).Results indicated that specific activity of 137Cs in soils at 1000 m is495-528 Bq m^-2,andat3200 mis10,500-11,470 Bq m^-2.No correlation observed for 137Cs versus naturally occurring radionuclides,which varies in distribution by altitude.Specific activities of 137Cs in dry atmospheric depositions varies from 1.06 at 846 m to2.37 Bq m^-2 per quarter at 3200 m and increases as the altitude increases.Activities of 137Cs in soil and dry atmospheric deposition correlated significantly,and 137Cs activity in soils and atmospheric dry depositions decrease as the absolute altitude decreases.The 50-year effective dose from exposure to 137Cs fallout varies with altitude from 0.007 to 1.42 m Sv.展开更多
The subject of the PDF (Probability Density Function) of the irradiance fluctuations in a turbulent atmosphere is still unsettled.Theory reliably describes the behavior in the weak turbulence regime,but theoretical de...The subject of the PDF (Probability Density Function) of the irradiance fluctuations in a turbulent atmosphere is still unsettled.Theory reliably describes the behavior in the weak turbulence regime,but theoretical description in the strong and whole turbulence regimes are still controversial.Based on Born perturbation theory,the physical manifestations and correlations of three typical PDF models (Rice-Nakagami,exponential-Bessel and negative-exponential distribution) were theoretically analyzed.It is shown that these models can be derived by separately making circular-Gaussian,strong-turbulence and strong-turbulence-circular-Gaussian approximations in Born perturbation theory,which denies the viewpoint that the Rice-Nakagami model is only applicable in the extremely weak turbulence regime and provides theoretical arguments for choosing rational models in practical applications.In addition,a common shortcoming of the three models is that they are all approximations.A new model,called the Maclaurin-spread distribution,is proposed without any approximation except for assuming the correlation coefficient to be zero.So,it is considered that the new model can exactly reflect the Born perturbation theory.Simulated results prove the accuracy of this new model.展开更多
基金a Grant No. 15T-1E061 ‘‘Radioecological Monitoring in the Area of the Republic of Armenia’’ 2015–2017, under support of State Committee of Science to the Ministry of Education and Science RA
文摘This paper considers the distribution of technogenic 137Cs and naturally occurring radionuclides:238 U,232 Th and40 R concentrations in soils and 137Cs in atmospheric dry depositions by altitudinal belts of the Aragats mountain massif,Republic of Armenia.Undisturbed soil samples were collected at altitudes from 1000 to 3200 m.For the determination of geochemical variability,two soil sampling campaigns were undertaken.Atmospheric dry depositions were sampled from five stations at1100-3200 m collected onto organic fiber filters between June and December 2016.137Cs activity was measured using a high-purity Germanium detector coupled to a multichannel analyzer(Canberra).Results indicated that specific activity of 137Cs in soils at 1000 m is495-528 Bq m^-2,andat3200 mis10,500-11,470 Bq m^-2.No correlation observed for 137Cs versus naturally occurring radionuclides,which varies in distribution by altitude.Specific activities of 137Cs in dry atmospheric depositions varies from 1.06 at 846 m to2.37 Bq m^-2 per quarter at 3200 m and increases as the altitude increases.Activities of 137Cs in soil and dry atmospheric deposition correlated significantly,and 137Cs activity in soils and atmospheric dry depositions decrease as the absolute altitude decreases.The 50-year effective dose from exposure to 137Cs fallout varies with altitude from 0.007 to 1.42 m Sv.
基金supported by the Special Foundation Program for Taishan Mountain Scholars
文摘The subject of the PDF (Probability Density Function) of the irradiance fluctuations in a turbulent atmosphere is still unsettled.Theory reliably describes the behavior in the weak turbulence regime,but theoretical description in the strong and whole turbulence regimes are still controversial.Based on Born perturbation theory,the physical manifestations and correlations of three typical PDF models (Rice-Nakagami,exponential-Bessel and negative-exponential distribution) were theoretically analyzed.It is shown that these models can be derived by separately making circular-Gaussian,strong-turbulence and strong-turbulence-circular-Gaussian approximations in Born perturbation theory,which denies the viewpoint that the Rice-Nakagami model is only applicable in the extremely weak turbulence regime and provides theoretical arguments for choosing rational models in practical applications.In addition,a common shortcoming of the three models is that they are all approximations.A new model,called the Maclaurin-spread distribution,is proposed without any approximation except for assuming the correlation coefficient to be zero.So,it is considered that the new model can exactly reflect the Born perturbation theory.Simulated results prove the accuracy of this new model.
