A Levenberg–Marquardt Gaussian fitting algorithm has been used for analyzing the overlap of three peaks(the 583-ke V peak of^(208)Tl, the 609-ke V peak of214 Bi, and the 662-ke V peak of^(137)Cs) using an in situ Na ...A Levenberg–Marquardt Gaussian fitting algorithm has been used for analyzing the overlap of three peaks(the 583-ke V peak of^(208)Tl, the 609-ke V peak of214 Bi, and the 662-ke V peak of^(137)Cs) using an in situ Na I(Tl) scintillation spectrometer. The algorithm, in addition,was compared with a genetic algorithm used for multiple deconvolution. The three fitted peak areas(583, 609, and662 ke V) were calculated from the measured gamma-ray spectra obtained from a simulation experiment in which a^(137) Cs source was buried at different soil depths(from 18 to38 cm). The application of the Levenberg–Marquardt algorithm yielded similar results compared to the genetic algorithm. A lack-of-fit test showed that the fitting is good when the instrumental noise levels were estimated from replicated analyses. The relative fitting error of the total net area and the residual standard deviation were within 5 %and 0.04, respectively, and the goodness of the fitting was better than 0.98. While the methods used in this paper give high performance, the results may lead to incorrect estimation when the signal-to-noise ratio is smaller than-30 d B. This study is useful for the determination of radioactive specific activity of^(137) Cs by in situ spectrometry.展开更多
Equilibrium moisture content （EMC） data for rough rice of thirteen Chinese varieties were obtained by static gravimetric method at five different temperatures （10, 20, 25, 30, and 35 ℃） and 11% to 96% equilibrium...Equilibrium moisture content （EMC） data for rough rice of thirteen Chinese varieties were obtained by static gravimetric method at five different temperatures （10, 20, 25, 30, and 35 ℃） and 11% to 96% equilibrium relative humidity （ERH）. Six models, i.e., Brunauer-Emmett-Teller, Guggenheim-Anderson-deBoer, Modified Chung-Pfost （MCPE）, Modified Henderson, Modified Oswin, and Strohman-Yoerger （STYE） fitted the EMC/ERH data based on the coefficient of determination, residue sum-of-squares, standard error of estimate, and mean relative percent error. The best fitted equations were MCPE and STYE, but MCPE is three-parameter, readily transformed equation and adopted in this study. The isosteric heats for both rough rice desorption and adsorption, and for both the sorption of Japonica and Indica rice, decreased rapidly with an increase in seed moisture content （m.c.） until the m.c. of 20% dry basis （d.b.） reached, and thereafter they decreased smoothly with increasing moisture content. The isosteric heats of rough rice desorption were higher than those of adsorption below the m.c. of 22.5% d.b., but thereafter, there was no significant difference found between desorption and adsorption. The sorption isosteric heats of Indica rice were slightly higher than those of Japonica rice under all moisture contents at a constant temperature. These results provide a sound basis for future work on the drying and storage of rice.展开更多
基金supported by the National Natural Science Foundation of China(No.41474107)
文摘A Levenberg–Marquardt Gaussian fitting algorithm has been used for analyzing the overlap of three peaks(the 583-ke V peak of^(208)Tl, the 609-ke V peak of214 Bi, and the 662-ke V peak of^(137)Cs) using an in situ Na I(Tl) scintillation spectrometer. The algorithm, in addition,was compared with a genetic algorithm used for multiple deconvolution. The three fitted peak areas(583, 609, and662 ke V) were calculated from the measured gamma-ray spectra obtained from a simulation experiment in which a^(137) Cs source was buried at different soil depths(from 18 to38 cm). The application of the Levenberg–Marquardt algorithm yielded similar results compared to the genetic algorithm. A lack-of-fit test showed that the fitting is good when the instrumental noise levels were estimated from replicated analyses. The relative fitting error of the total net area and the residual standard deviation were within 5 %and 0.04, respectively, and the goodness of the fitting was better than 0.98. While the methods used in this paper give high performance, the results may lead to incorrect estimation when the signal-to-noise ratio is smaller than-30 d B. This study is useful for the determination of radioactive specific activity of^(137) Cs by in situ spectrometry.
文摘Equilibrium moisture content （EMC） data for rough rice of thirteen Chinese varieties were obtained by static gravimetric method at five different temperatures （10, 20, 25, 30, and 35 ℃） and 11% to 96% equilibrium relative humidity （ERH）. Six models, i.e., Brunauer-Emmett-Teller, Guggenheim-Anderson-deBoer, Modified Chung-Pfost （MCPE）, Modified Henderson, Modified Oswin, and Strohman-Yoerger （STYE） fitted the EMC/ERH data based on the coefficient of determination, residue sum-of-squares, standard error of estimate, and mean relative percent error. The best fitted equations were MCPE and STYE, but MCPE is three-parameter, readily transformed equation and adopted in this study. The isosteric heats for both rough rice desorption and adsorption, and for both the sorption of Japonica and Indica rice, decreased rapidly with an increase in seed moisture content （m.c.） until the m.c. of 20% dry basis （d.b.） reached, and thereafter they decreased smoothly with increasing moisture content. The isosteric heats of rough rice desorption were higher than those of adsorption below the m.c. of 22.5% d.b., but thereafter, there was no significant difference found between desorption and adsorption. The sorption isosteric heats of Indica rice were slightly higher than those of Japonica rice under all moisture contents at a constant temperature. These results provide a sound basis for future work on the drying and storage of rice.
