In order to overcome the effect of the assumption between emissivity and wavelength on the measurement of true temperature and spectral emissivity for most engineering materials, a neural network based method is propo...In order to overcome the effect of the assumption between emissivity and wavelength on the measurement of true temperature and spectral emissivity for most engineering materials, a neural network based method is proposed for data processing while a blackbody furnace and three optical filters with known spectral transmittance curves were used to make up a true target. The experimental results show that the calculated temperatures are in good agreement with the temperature of the blackbody furnace, and the calculated spectral emissivity curves are in good agreement with the spectral transmittance curves of the filters. The method proposed has been proved to be an effective method for solving the problem of true temperature and emissivity measurement, and it can overcome the effect of the assumption between emissivity and wavelength on the measurement of true temperature and spectral emissivity for most engineering materials.展开更多
Present study is carried out in the bone samples collected from Roopkund Lake in district Chamoli Garhwal, Uttarakhand which is located at 5,029 meters from main sea level in between Nanda Ghunghti and Trishuli peak. ...Present study is carried out in the bone samples collected from Roopkund Lake in district Chamoli Garhwal, Uttarakhand which is located at 5,029 meters from main sea level in between Nanda Ghunghti and Trishuli peak. This historical site belongs to 9th century A.D. All the samples selected for the study were dried in room temperature as well as hot air oven at 32 ~C. Cleaning, pretreatment and digestion process of faunal remains was followed through established scientific methods. Chemical analysis i.e. concentration of different elements such as calcium, strontium, barium, magnesium and zinc as well as isotopic ratios of Carbon and Nitrogen was estimated with the help of ICP （inductively coupled plasma spectroscopy） and AAS （atomic absorption spectrophotometer）. The results obtained from the chemical analysis are significant. On the basis of concentration of different elements and ratios of Nitrogen and Carbon isotopes, the dietary habits of the peoples buried in the Roopkund Lake are identified, which is different from sample to sample person to person. Besides this, the results are also significantly helpful for knowing the preservation status of faunal remains in Roopkund Lake. Finally this study also indicated the potentiality of chemical analysis for reconstructing the palaeodiet behaviour and preservation status of bone remains.展开更多
The BaAl2Si2O8:Eu2+blue emitting phosphor was obtained through the one-step calcination process of precursors prepared bychemical co-precipitation method. The phase structure and luminescence propertied of the phospho...The BaAl2Si2O8:Eu2+blue emitting phosphor was obtained through the one-step calcination process of precursors prepared bychemical co-precipitation method. The phase structure and luminescence propertied of the phosphor were investigated usingX-ray diffraction (XRD) and a fluorescence spectrophotometer. The excitation spectrum exhibited a broad band between 230nm and 400 nm and the emission peaking at about 470 nm was observed, which originated from the allowed f-d transition ofEu2+ions at Ba2+sites. Owing to the different optimal concentrations under different excitation wavelengths (254 nm and 365nm), the energy-transfer mechanism in this phosphor has changed from the dipole-dipole interaction to the exchange interac-tion of Eu2+ions.展开更多
文摘In order to overcome the effect of the assumption between emissivity and wavelength on the measurement of true temperature and spectral emissivity for most engineering materials, a neural network based method is proposed for data processing while a blackbody furnace and three optical filters with known spectral transmittance curves were used to make up a true target. The experimental results show that the calculated temperatures are in good agreement with the temperature of the blackbody furnace, and the calculated spectral emissivity curves are in good agreement with the spectral transmittance curves of the filters. The method proposed has been proved to be an effective method for solving the problem of true temperature and emissivity measurement, and it can overcome the effect of the assumption between emissivity and wavelength on the measurement of true temperature and spectral emissivity for most engineering materials.
文摘Present study is carried out in the bone samples collected from Roopkund Lake in district Chamoli Garhwal, Uttarakhand which is located at 5,029 meters from main sea level in between Nanda Ghunghti and Trishuli peak. This historical site belongs to 9th century A.D. All the samples selected for the study were dried in room temperature as well as hot air oven at 32 ~C. Cleaning, pretreatment and digestion process of faunal remains was followed through established scientific methods. Chemical analysis i.e. concentration of different elements such as calcium, strontium, barium, magnesium and zinc as well as isotopic ratios of Carbon and Nitrogen was estimated with the help of ICP （inductively coupled plasma spectroscopy） and AAS （atomic absorption spectrophotometer）. The results obtained from the chemical analysis are significant. On the basis of concentration of different elements and ratios of Nitrogen and Carbon isotopes, the dietary habits of the peoples buried in the Roopkund Lake are identified, which is different from sample to sample person to person. Besides this, the results are also significantly helpful for knowing the preservation status of faunal remains in Roopkund Lake. Finally this study also indicated the potentiality of chemical analysis for reconstructing the palaeodiet behaviour and preservation status of bone remains.
基金supported by the Scientific and Technological Project of Chongqing, China (Grant No. CSTC, 2009AB4171)the Innovation Foundation for Technology Based Firms of Ministry of Science and Technology, China (Grant No. 04C26225100807)
文摘The BaAl2Si2O8:Eu2+blue emitting phosphor was obtained through the one-step calcination process of precursors prepared bychemical co-precipitation method. The phase structure and luminescence propertied of the phosphor were investigated usingX-ray diffraction (XRD) and a fluorescence spectrophotometer. The excitation spectrum exhibited a broad band between 230nm and 400 nm and the emission peaking at about 470 nm was observed, which originated from the allowed f-d transition ofEu2+ions at Ba2+sites. Owing to the different optimal concentrations under different excitation wavelengths (254 nm and 365nm), the energy-transfer mechanism in this phosphor has changed from the dipole-dipole interaction to the exchange interac-tion of Eu2+ions.
