This study reports the performances of efficiency calibrations for high-purity-germanium gamma-ray spectrometry using the source-, Laboratory Sourceless Object Calibration Software(LabSOCS)-and ANGLE-based methods in ...This study reports the performances of efficiency calibrations for high-purity-germanium gamma-ray spectrometry using the source-, Laboratory Sourceless Object Calibration Software(LabSOCS)-and ANGLE-based methods in an inter-comparison exercise. Although the results of LabSOCS and ANGLE for ^(241)Am emitting lowenergy gamma rays were not very satisfactory, all of the three efficiency calibration methods passed acceptance criteria. The results confirmed the reliability of the calculation codes ANGLE and LabSOCS as alternative efficiency calibration methods in high-purity-germanium gamma spectrometry. This study is likely to promote the further application of the ANGLE and LabSOCS calculation codes in radioactivity measurements.展开更多
Increasing complexity of distributed hydrological model(DHM)has lowered the efficiency of convergence.In this study,global sensitivity analysis(SA)was introduced by combining multiobjective(MO)optimization for DHM cal...Increasing complexity of distributed hydrological model(DHM)has lowered the efficiency of convergence.In this study,global sensitivity analysis(SA)was introduced by combining multiobjective(MO)optimization for DHM calibration.Latin Hypercube-once at a time(LH-OAT)was adopted in global parameter SA to obtain relative sensitivity of model parameter,which can be categorized into different sensitivity levels.Two comparative study cases were conducted to present the efficiency and feasibility by combining SA with MO(SA-MO).WetSpa model with non-dominated sorting genetic algorithm-Ⅱ(NSGA-Ⅱ)algorithm and EasyDHM model with multi-objective sequential complex evolutionary metropolis-uncertainty analysis(MOSCEM-UA)algorithm were adopted to demonstrate the general feasibility of combining SA in optimization.Results showed that the LH-OAT was globally effective in selecting high sensitivity parameters.It proves that using parameter from high sensitivity groups results in higher convergence efficiency.Study case I showed a better Pareto front distribution and convergence compared with model calibration without SA.Study case II indicated a more efficient convergence of parameters in sequential evolution of MOSCEM-UA under the same iteration.It indicates that SA-MO is feasible and efficient for high dimensional DHM calibration.展开更多
Correlated photon is exploited as a tool for absolute quantum efficiency calibration of photon detectors working in the photon-counting regime. We extend the method from photon-counting regime to the absolute calibrat...Correlated photon is exploited as a tool for absolute quantum efficiency calibration of photon detectors working in the photon-counting regime. We extend the method from photon-counting regime to the absolute calibration of analog regime photon detectors. A revised calibration module is proposed based on balance detection and fluctuation restrictions conditions applied to analog photon detectors. An absolute calibration experimental system is established. This method shows a relative standard uncertainty of 2.1% and a relative deviation of 1% compared with those of the typical photomultiplier quantum efficiency.展开更多
基金supported by the Support Program of the Ministry of Science and Technology(No.2014FY211000)the National Key Technology Research and Development Program(No.2013BAK03B05)
文摘This study reports the performances of efficiency calibrations for high-purity-germanium gamma-ray spectrometry using the source-, Laboratory Sourceless Object Calibration Software(LabSOCS)-and ANGLE-based methods in an inter-comparison exercise. Although the results of LabSOCS and ANGLE for ^(241)Am emitting lowenergy gamma rays were not very satisfactory, all of the three efficiency calibration methods passed acceptance criteria. The results confirmed the reliability of the calculation codes ANGLE and LabSOCS as alternative efficiency calibration methods in high-purity-germanium gamma spectrometry. This study is likely to promote the further application of the ANGLE and LabSOCS calculation codes in radioactivity measurements.
基金National Basic Research Program(973)of China(No.2010CB951102)Innovative Research Groups of the National Natural Science Foundation,China(No.51021006)National Natural Science Foundation of China(No.51079028)
文摘Increasing complexity of distributed hydrological model(DHM)has lowered the efficiency of convergence.In this study,global sensitivity analysis(SA)was introduced by combining multiobjective(MO)optimization for DHM calibration.Latin Hypercube-once at a time(LH-OAT)was adopted in global parameter SA to obtain relative sensitivity of model parameter,which can be categorized into different sensitivity levels.Two comparative study cases were conducted to present the efficiency and feasibility by combining SA with MO(SA-MO).WetSpa model with non-dominated sorting genetic algorithm-Ⅱ(NSGA-Ⅱ)algorithm and EasyDHM model with multi-objective sequential complex evolutionary metropolis-uncertainty analysis(MOSCEM-UA)algorithm were adopted to demonstrate the general feasibility of combining SA in optimization.Results showed that the LH-OAT was globally effective in selecting high sensitivity parameters.It proves that using parameter from high sensitivity groups results in higher convergence efficiency.Study case I showed a better Pareto front distribution and convergence compared with model calibration without SA.Study case II indicated a more efficient convergence of parameters in sequential evolution of MOSCEM-UA under the same iteration.It indicates that SA-MO is feasible and efficient for high dimensional DHM calibration.
基金the National High-tech R&D Program(No.2015AA123702)the National Natural Science Foundation of China(Nos.61275173,11204318)
文摘Correlated photon is exploited as a tool for absolute quantum efficiency calibration of photon detectors working in the photon-counting regime. We extend the method from photon-counting regime to the absolute calibration of analog regime photon detectors. A revised calibration module is proposed based on balance detection and fluctuation restrictions conditions applied to analog photon detectors. An absolute calibration experimental system is established. This method shows a relative standard uncertainty of 2.1% and a relative deviation of 1% compared with those of the typical photomultiplier quantum efficiency.
