A practical regression method of saturation exponential in pre-dose technique is proposed. The method is mainly applied for porcelain datillg. To test the method, some simulated paleodoses of the imitations of ancient...A practical regression method of saturation exponential in pre-dose technique is proposed. The method is mainly applied for porcelain datillg. To test the method, some simulated paleodoses of the imitations of ancient porcelain were used. The measured results are in good agreement with the simulated values of the paleodoses, and the average ratios of the two values by using the two ways are 1.05 and 0.99 with standard deviations (±lσ) of 19% and 15% respectively. Such errors can be accepted in porcelain dating.展开更多
The low-lying spectra of parabolic quantum dots with or without an impurity at the center are investigated.While it has been known that the electron-electron interaction leads to ground-state transitions on magic valu...The low-lying spectra of parabolic quantum dots with or without an impurity at the center are investigated.While it has been known that the electron-electron interaction leads to ground-state transitions on magic values of angular momentum in a magnetic field. We show, in this paper, that the implantation of an impurity ion at the center can either enhance or suppress such transitions, depending on whether it is an acceptor or a donor ion.展开更多
EDXRF spectromerty was applied to provenance studies of Neolitic Age(from 6000 BCto 2000 BC)pottery sherds excavated from Gansu Province in north-west China。Major and trace components analysis of te pottery specimen ...EDXRF spectromerty was applied to provenance studies of Neolitic Age(from 6000 BCto 2000 BC)pottery sherds excavated from Gansu Province in north-west China。Major and trace components analysis of te pottery specimen was carried out,and the artificial neural networks has been used to classift the trace com-ponent of these pottery。The results shown that pottery exchange had been existed during 3000 BC in ancient Gansu Province,China。展开更多
Several nc-TiN/a-TiB2 thin films comprised of nanocrystalline (nc-) TiN and amor phous (a-) TiB2 phases were deposited on Si(100) at room temperature by reactive unbalanced dc magnetron sputtering, followed by vacuum ...Several nc-TiN/a-TiB2 thin films comprised of nanocrystalline (nc-) TiN and amor phous (a-) TiB2 phases were deposited on Si(100) at room temperature by reactive unbalanced dc magnetron sputtering, followed by vacuum annealed at 400, 600, 80 0 and 1000℃ for 1h, respectively. Effects of B content on microstructure, mecha nical behaviors and thermal microstructure stability have been investigated by X -ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and nanoindentation measurements. The results indicated that B addition greatly affected both microstructure and mechanical behavior of nc-Ti N/a-TiB2 thin films. With increasing B content the grain size decreased. A maxim um hardness value of about 33GPa was obtained at B content of about 19at.%. The improved mechanical properties of nc-TiN/a-TiB2 films with the addition of B int o TiN were attributed to their densified microstructure with development of fine grain size. Only addition of sufficient B could restrain grain growth during an nealing. High B content resulted in high microstructure stability. The crystalli zation of amorphous matrix occurred at about 800℃, forming TiB or TiB2 crystall ite, depending on B content. Before that no change in bonding configuration was found.展开更多
In routine thermoluminescence(TL) dating,there is often a tendency to omit an absolute determination of the thorium and uranium content in the sample and simply measure the total alpha count rate.The annual dose is th...In routine thermoluminescence(TL) dating,there is often a tendency to omit an absolute determination of the thorium and uranium content in the sample and simply measure the total alpha count rate.The annual dose is then calculated assuming equal activities for a Th/U weight ratio of about 3.17. In fact this ratio is varied significantly in pottery.Calculation of the annual dose conversion factors from data using the total alpha count rate in a selected range of Th/U weight ratios shows significant differences.The results indicate that the additional error contribution to the final TL age is in the range ±2.5%to±4.1% for most cases where the Th/U ratio lies between 1.1 and 9.5.展开更多
Most of the natural occurring radionuclides in both noodles and bread are found to have specific activities below the detectable limit of the high purity germanium (n-type) spectrometer system of the EG&G Ortec C...Most of the natural occurring radionuclides in both noodles and bread are found to have specific activities below the detectable limit of the high purity germanium (n-type) spectrometer system of the EG&G Ortec Company. For dried bread, 40K,137Cs and 60Co are found to be 44.45￣84.52, < 0.012 ￣0.052, < 0.018 ￣0.054 Bq/kg;for noodles, to be 29.55￣64.54, < 0.01 ￣0.069 and < 9.8× 10-3 ￣ 0.074 Bq/kg,respectively. The weighted committed dose equivalents due to the ingestion of 137Csfrom noodles and bread for a male and female adults have been estimated to be 0.5and 0.6μSv, respectively, being less than the values recommended by ICRP.展开更多
A compartment model is employed to calculate the radionuclide concentrations in the ocean currents for a nuclear accient scenario where the long-lived 137Cs is totally discharged into the sea. The radionuclide concent...A compartment model is employed to calculate the radionuclide concentrations in the ocean currents for a nuclear accient scenario where the long-lived 137Cs is totally discharged into the sea. The radionuclide concentrations in both the waters of Daya Bay and the adjacent South China Sea are considered. Using the concentration factors for the marine organisms: fish, crustacea and mollusca, their radionuclide concentrations are also estimated. In this way, the whole body radiation doses received by an individual due to ingestion of marine organisms from the Daya Bay and the South China Sea are calculated.展开更多
Friction and sliding wear behaviour of Ti-B-N coatings against AISI440C steel ba ll and WC-6wt%Co ball were studied by using pin-on-disk tribometer along with mi crostructure characterization using optical microscopy ...Friction and sliding wear behaviour of Ti-B-N coatings against AISI440C steel ba ll and WC-6wt%Co ball were studied by using pin-on-disk tribometer along with mi crostructure characterization using optical microscopy (OM), scanning electron m icroscopy (SEM) and X-ray photoelectron spectroscopy (XPS). It is shown that the wear resistance of film depended on the wear mechanism. In the case of AISI440C steel, adhesive wear were pre-dominant and the wear rate increased sharply to a maximum when N content reach ~38at.%. This might be related to the change of fi lm microstructure and phase configuration, so the least adhesive transfer of tri bo-film was observed. If WC-6wt%Co ball was used, less deformation wear debris w as observed, this was responsible for the rise of wear rate. Despite of differen t wear modes, friction coefficients in both cases were found to depend mainly on the formation and the amount of h-BN phase. Elemental analysis by energy disper sive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) revealed that oxygen participated in the wear behavior by reacting with films to form the deb ris comprised of various types of Ti oxide including TiO, TiO2 and Ti2O3 , which increased wear resistance.展开更多
Radionuclide contents in imported rice are determined using the EG&G ORTEC photon spectrometer system. Most of the natural radionuclides are found to have specific activities below the detectable limit. 40K has va...Radionuclide contents in imported rice are determined using the EG&G ORTEC photon spectrometer system. Most of the natural radionuclides are found to have specific activities below the detectable limit. 40K has values ranging from 0.104to 32.97 Bq/kg; 137Cs from 0.009 to 0.52 Bq/kg; and 95Zr less than 0.077 Bq/kg. The annual effective dose for a male and a female adult is 18μSv and 12.7μSv, respectively. Both are less than the value recommended by the International Commission of Radiological Protection.展开更多
Ab initio total energy calculations are used to determine the interface structure of GaN films grown on 6H-SiC(0001)with different substrate reconstructions.The results indicate that GaN films grown on bare SiC(0001)a...Ab initio total energy calculations are used to determine the interface structure of GaN films grown on 6H-SiC(0001)with different substrate reconstructions.The results indicate that GaN films grown on bare SiC(0001)are of the Ga-polarity,while GaN films grown on SiC(0001)with Si adlayer are of the N-polarity if there is no N-Si interchange at the interface.With the interchange,the GaN films are of the Ga-polarity.展开更多
Measurements of radiation dose to patients in spiral computed tomography (CT) were completed for various collimations,table speeds and pitch. A standard CT head dosimetry phantom and thermoluminescent dosime- ters (TL...Measurements of radiation dose to patients in spiral computed tomography (CT) were completed for various collimations,table speeds and pitch. A standard CT head dosimetry phantom and thermoluminescent dosime- ters (TLD) were used for the measurement. The effect of collimation and pitch on radiation dose was studied. The results indicated that the radiation dose at the given tube current,voltage and rotation speed was inversely propor- tional to pitch. And the increasing times of dose were as decreasing times of pitch. This regular pattern was tenable for radiation dose at both central holes and peripheral holes of the phantom at pitch = 1,>1 and <1. The collimation had no impact on the radiation dose. The results also indicated that radiation dose at central holes was nearly equal to that at peripheral holes. There was no significant difference between them statistically. The study demonstrates that the pitch in spiral CT scans is the primary parameter and has significant impact on radiation dose.展开更多
A rapid and effective TL technique to authenticate ancient Chinese pottery is proposed in the paper. Twenty three samples, ranging in age from 200 to 9000 a,including multiple styles and shapes and drawn from diverse ...A rapid and effective TL technique to authenticate ancient Chinese pottery is proposed in the paper. Twenty three samples, ranging in age from 200 to 9000 a,including multiple styles and shapes and drawn from diverse and remote areas in China have been used to establish the typical annual dose as 5.5mGy/a and its associated deviation. Ten unauthenticated samples are then appraised using the technique which,in nearly all cases, leads to satisfactory results.展开更多
Generally, the walls of ceramic ware are thin and the sample to be used for TL dating has to be collected from 1￣2mm under the surface.This call introduce significant error into the dating method.Therefore,the result...Generally, the walls of ceramic ware are thin and the sample to be used for TL dating has to be collected from 1￣2mm under the surface.This call introduce significant error into the dating method.Therefore,the results of a series of simulated experiments are reported on the build-up effect of the internal β dose response in different thicknesses of pottery fragments (involving tile and brick).Correction factors,corresponding to different thicknesses,and correction 'depths' are proposed in terms of the experimental findings which may be incorporatd into the dating methods.展开更多
In order to further understand the similarity and difference betweendeformation mechanisms of single crystals and poly-crystalline materials, the influence of externalconstraint and rolling geometry on the deformation...In order to further understand the similarity and difference betweendeformation mechanisms of single crystals and poly-crystalline materials, the influence of externalconstraint and rolling geometry on the deformation behaviour of copper single crystals with{123}<634> orientation was investigated by embedding them into metal frames of different strengths.The metal frames were made of aluminum and mild steel, respectively. The results show that thedeformation banding degree of the crystal increases with the strength of metal frame and shearstrain. For the crystals rolled under lower (gamma)g ((gamma)g is the ratio of the geometricalredundant shear strain to the normal rolling strain), the deformation is homogeneous. For thecrystals rolled under higher (gamma)g, the deformation is extremely inhomogeneous. The deformationis more homogeneous in the crystals rolled in steel frames than that rolled in aluminum frames. TheS-orientation is more stable in the crystals rolled under lower (gamma)g than that rolled underhigher (gamma)g.展开更多
文摘A practical regression method of saturation exponential in pre-dose technique is proposed. The method is mainly applied for porcelain datillg. To test the method, some simulated paleodoses of the imitations of ancient porcelain were used. The measured results are in good agreement with the simulated values of the paleodoses, and the average ratios of the two values by using the two ways are 1.05 and 0.99 with standard deviations (±lσ) of 19% and 15% respectively. Such errors can be accepted in porcelain dating.
文摘The low-lying spectra of parabolic quantum dots with or without an impurity at the center are investigated.While it has been known that the electron-electron interaction leads to ground-state transitions on magic values of angular momentum in a magnetic field. We show, in this paper, that the implantation of an impurity ion at the center can either enhance or suppress such transitions, depending on whether it is an acceptor or a donor ion.
文摘EDXRF spectromerty was applied to provenance studies of Neolitic Age(from 6000 BCto 2000 BC)pottery sherds excavated from Gansu Province in north-west China。Major and trace components analysis of te pottery specimen was carried out,and the artificial neural networks has been used to classift the trace com-ponent of these pottery。The results shown that pottery exchange had been existed during 3000 BC in ancient Gansu Province,China。
文摘Several nc-TiN/a-TiB2 thin films comprised of nanocrystalline (nc-) TiN and amor phous (a-) TiB2 phases were deposited on Si(100) at room temperature by reactive unbalanced dc magnetron sputtering, followed by vacuum annealed at 400, 600, 80 0 and 1000℃ for 1h, respectively. Effects of B content on microstructure, mecha nical behaviors and thermal microstructure stability have been investigated by X -ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and nanoindentation measurements. The results indicated that B addition greatly affected both microstructure and mechanical behavior of nc-Ti N/a-TiB2 thin films. With increasing B content the grain size decreased. A maxim um hardness value of about 33GPa was obtained at B content of about 19at.%. The improved mechanical properties of nc-TiN/a-TiB2 films with the addition of B int o TiN were attributed to their densified microstructure with development of fine grain size. Only addition of sufficient B could restrain grain growth during an nealing. High B content resulted in high microstructure stability. The crystalli zation of amorphous matrix occurred at about 800℃, forming TiB or TiB2 crystall ite, depending on B content. Before that no change in bonding configuration was found.
文摘In routine thermoluminescence(TL) dating,there is often a tendency to omit an absolute determination of the thorium and uranium content in the sample and simply measure the total alpha count rate.The annual dose is then calculated assuming equal activities for a Th/U weight ratio of about 3.17. In fact this ratio is varied significantly in pottery.Calculation of the annual dose conversion factors from data using the total alpha count rate in a selected range of Th/U weight ratios shows significant differences.The results indicate that the additional error contribution to the final TL age is in the range ±2.5%to±4.1% for most cases where the Th/U ratio lies between 1.1 and 9.5.
文摘Most of the natural occurring radionuclides in both noodles and bread are found to have specific activities below the detectable limit of the high purity germanium (n-type) spectrometer system of the EG&G Ortec Company. For dried bread, 40K,137Cs and 60Co are found to be 44.45￣84.52, < 0.012 ￣0.052, < 0.018 ￣0.054 Bq/kg;for noodles, to be 29.55￣64.54, < 0.01 ￣0.069 and < 9.8× 10-3 ￣ 0.074 Bq/kg,respectively. The weighted committed dose equivalents due to the ingestion of 137Csfrom noodles and bread for a male and female adults have been estimated to be 0.5and 0.6μSv, respectively, being less than the values recommended by ICRP.
文摘A compartment model is employed to calculate the radionuclide concentrations in the ocean currents for a nuclear accient scenario where the long-lived 137Cs is totally discharged into the sea. The radionuclide concentrations in both the waters of Daya Bay and the adjacent South China Sea are considered. Using the concentration factors for the marine organisms: fish, crustacea and mollusca, their radionuclide concentrations are also estimated. In this way, the whole body radiation doses received by an individual due to ingestion of marine organisms from the Daya Bay and the South China Sea are calculated.
文摘Friction and sliding wear behaviour of Ti-B-N coatings against AISI440C steel ba ll and WC-6wt%Co ball were studied by using pin-on-disk tribometer along with mi crostructure characterization using optical microscopy (OM), scanning electron m icroscopy (SEM) and X-ray photoelectron spectroscopy (XPS). It is shown that the wear resistance of film depended on the wear mechanism. In the case of AISI440C steel, adhesive wear were pre-dominant and the wear rate increased sharply to a maximum when N content reach ~38at.%. This might be related to the change of fi lm microstructure and phase configuration, so the least adhesive transfer of tri bo-film was observed. If WC-6wt%Co ball was used, less deformation wear debris w as observed, this was responsible for the rise of wear rate. Despite of differen t wear modes, friction coefficients in both cases were found to depend mainly on the formation and the amount of h-BN phase. Elemental analysis by energy disper sive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) revealed that oxygen participated in the wear behavior by reacting with films to form the deb ris comprised of various types of Ti oxide including TiO, TiO2 and Ti2O3 , which increased wear resistance.
文摘Radionuclide contents in imported rice are determined using the EG&G ORTEC photon spectrometer system. Most of the natural radionuclides are found to have specific activities below the detectable limit. 40K has values ranging from 0.104to 32.97 Bq/kg; 137Cs from 0.009 to 0.52 Bq/kg; and 95Zr less than 0.077 Bq/kg. The annual effective dose for a male and a female adult is 18μSv and 12.7μSv, respectively. Both are less than the value recommended by the International Commission of Radiological Protection.
文摘Ab initio total energy calculations are used to determine the interface structure of GaN films grown on 6H-SiC(0001)with different substrate reconstructions.The results indicate that GaN films grown on bare SiC(0001)are of the Ga-polarity,while GaN films grown on SiC(0001)with Si adlayer are of the N-polarity if there is no N-Si interchange at the interface.With the interchange,the GaN films are of the Ga-polarity.
文摘Measurements of radiation dose to patients in spiral computed tomography (CT) were completed for various collimations,table speeds and pitch. A standard CT head dosimetry phantom and thermoluminescent dosime- ters (TLD) were used for the measurement. The effect of collimation and pitch on radiation dose was studied. The results indicated that the radiation dose at the given tube current,voltage and rotation speed was inversely propor- tional to pitch. And the increasing times of dose were as decreasing times of pitch. This regular pattern was tenable for radiation dose at both central holes and peripheral holes of the phantom at pitch = 1,>1 and <1. The collimation had no impact on the radiation dose. The results also indicated that radiation dose at central holes was nearly equal to that at peripheral holes. There was no significant difference between them statistically. The study demonstrates that the pitch in spiral CT scans is the primary parameter and has significant impact on radiation dose.
文摘A rapid and effective TL technique to authenticate ancient Chinese pottery is proposed in the paper. Twenty three samples, ranging in age from 200 to 9000 a,including multiple styles and shapes and drawn from diverse and remote areas in China have been used to establish the typical annual dose as 5.5mGy/a and its associated deviation. Ten unauthenticated samples are then appraised using the technique which,in nearly all cases, leads to satisfactory results.
文摘Generally, the walls of ceramic ware are thin and the sample to be used for TL dating has to be collected from 1￣2mm under the surface.This call introduce significant error into the dating method.Therefore,the results of a series of simulated experiments are reported on the build-up effect of the internal β dose response in different thicknesses of pottery fragments (involving tile and brick).Correction factors,corresponding to different thicknesses,and correction 'depths' are proposed in terms of the experimental findings which may be incorporatd into the dating methods.
文摘In order to further understand the similarity and difference betweendeformation mechanisms of single crystals and poly-crystalline materials, the influence of externalconstraint and rolling geometry on the deformation behaviour of copper single crystals with{123}<634> orientation was investigated by embedding them into metal frames of different strengths.The metal frames were made of aluminum and mild steel, respectively. The results show that thedeformation banding degree of the crystal increases with the strength of metal frame and shearstrain. For the crystals rolled under lower (gamma)g ((gamma)g is the ratio of the geometricalredundant shear strain to the normal rolling strain), the deformation is homogeneous. For thecrystals rolled under higher (gamma)g, the deformation is extremely inhomogeneous. The deformationis more homogeneous in the crystals rolled in steel frames than that rolled in aluminum frames. TheS-orientation is more stable in the crystals rolled under lower (gamma)g than that rolled underhigher (gamma)g.
