Gamma-ray spectroscopy based on a 100% efficiency hyper-pure germanium detector was used to evaluate the activity concentrations of <sup>226</sup>Ra, <sup>232</sup>Th, and <sup>40</sup...Gamma-ray spectroscopy based on a 100% efficiency hyper-pure germanium detector was used to evaluate the activity concentrations of <sup>226</sup>Ra, <sup>232</sup>Th, and <sup>40</sup>K natural radionuclides in sedimentary, conglomerate, igneous and sedi-ments rock samples collected from four different locations in Eastern desert in Egypt. The obtained activity concentrations are used to evaluate the radi-ological hazards indices, absorbed dose rate, annual effective dose equivalent in air, radium equivalent, external and internal hazard index, radiation level index, annual gonadal dose equivalent, excess lifetime cancer risk and expo-sure rate. The results show that 1) the absorbed dose rate depends on the rock type, 2) the annual effective dose equivalent in air in 71% of sample below 20 mSvy<sup>-1</sup> (permissible limit for workers), 3) the conglomerate rocks show low radioactivity level, 4) sedimentary rocks are rich in radium while igneous rocks are rich in thorium and the sediments rocks are rich in both radium and thorium.展开更多
Nowadays global navigation satellite system(GNSS)receivers are the primary tool not only for precision surveying but also for geodesy,geophysics and many other industrial applications worldwide.The only way to assure ...Nowadays global navigation satellite system(GNSS)receivers are the primary tool not only for precision surveying but also for geodesy,geophysics and many other industrial applications worldwide.The only way to assure the accuracy,universality and longevity of GNSS measurements is by calibration of its receivers.The parameters affecting the calibration accuracy of a single GNSS receiver are discussed in this paper.And a geodetic basepoint is established according to previous empirical studies to serve as a reference for calibration.Additionally,the traceability to the systeme international(SI)unit of such kind of calibrations is discussed.Stability of the base point is also verified through long-term measurements over three years.Eventually,a calibration of a sample single GNSS receiver is performed and the uncertainty budget is derived.展开更多
The new standards for the photometric characterization of light-emitting diode(LED)sources and luminaries require the measurement evaluation of photometric and colorimetric quantities.This present work studies the per...The new standards for the photometric characterization of light-emitting diode(LED)sources and luminaries require the measurement evaluation of photometric and colorimetric quantities.This present work studies the performance of some types of LED light sources in different spectra and different color temperature for photometric and colorimetric applications.The study depends on mixed spectra of these different types of LEDs to enhance the color rendering index(CRI)to be near as possible to standard sources.Characterization of LED sources requires the evaluation of some photometric and colorimetric quantities such as luminous flux(),chromaticity coordinates(x,y)and(u′,v′),correlated color temperature(CCT)and color rending indices(CRI).展开更多
文摘Gamma-ray spectroscopy based on a 100% efficiency hyper-pure germanium detector was used to evaluate the activity concentrations of <sup>226</sup>Ra, <sup>232</sup>Th, and <sup>40</sup>K natural radionuclides in sedimentary, conglomerate, igneous and sedi-ments rock samples collected from four different locations in Eastern desert in Egypt. The obtained activity concentrations are used to evaluate the radi-ological hazards indices, absorbed dose rate, annual effective dose equivalent in air, radium equivalent, external and internal hazard index, radiation level index, annual gonadal dose equivalent, excess lifetime cancer risk and expo-sure rate. The results show that 1) the absorbed dose rate depends on the rock type, 2) the annual effective dose equivalent in air in 71% of sample below 20 mSvy<sup>-1</sup> (permissible limit for workers), 3) the conglomerate rocks show low radioactivity level, 4) sedimentary rocks are rich in radium while igneous rocks are rich in thorium and the sediments rocks are rich in both radium and thorium.
文摘Nowadays global navigation satellite system(GNSS)receivers are the primary tool not only for precision surveying but also for geodesy,geophysics and many other industrial applications worldwide.The only way to assure the accuracy,universality and longevity of GNSS measurements is by calibration of its receivers.The parameters affecting the calibration accuracy of a single GNSS receiver are discussed in this paper.And a geodetic basepoint is established according to previous empirical studies to serve as a reference for calibration.Additionally,the traceability to the systeme international(SI)unit of such kind of calibrations is discussed.Stability of the base point is also verified through long-term measurements over three years.Eventually,a calibration of a sample single GNSS receiver is performed and the uncertainty budget is derived.
文摘The new standards for the photometric characterization of light-emitting diode(LED)sources and luminaries require the measurement evaluation of photometric and colorimetric quantities.This present work studies the performance of some types of LED light sources in different spectra and different color temperature for photometric and colorimetric applications.The study depends on mixed spectra of these different types of LEDs to enhance the color rendering index(CRI)to be near as possible to standard sources.Characterization of LED sources requires the evaluation of some photometric and colorimetric quantities such as luminous flux(),chromaticity coordinates(x,y)and(u′,v′),correlated color temperature(CCT)and color rending indices(CRI).
