Introduction Non-evaporable getter is now widely employed in many accelerators to mitigate the resistive-wall effect of the Ti-Zr-V getter coated vacuum chambers in the next generation accelerators.Methods and discuss...Introduction Non-evaporable getter is now widely employed in many accelerators to mitigate the resistive-wall effect of the Ti-Zr-V getter coated vacuum chambers in the next generation accelerators.Methods and discussions Quaternary Ti-Zr-V-Cu getter films were deposited by direct current(DC)magnetron sputtering.The DC/high frequency impedance and activation kinetics were investigated by four-probes/waveguide methods and in situ synchrotron radiation photoelectron spectroscopy(SRPES).Conclusions Compared to Ti-Zr-V films,Ti-Zr-V-Cu films showed better conductivity,which is beneficial to eliminate the resistive-wall effect.However,its initial activation temperature is above 200℃,and it needs to be activated at a higher temperature to achieve the required pumping performance.展开更多
Many investigation techniques are commonly employed with the aim of estimating the spatial distribution of transmissivity. Unfortunately, the conventional methods for the determination of hydraulic parameters such as ...Many investigation techniques are commonly employed with the aim of estimating the spatial distribution of transmissivity. Unfortunately, the conventional methods for the determination of hydraulic parameters such as pumping tests, permeameter measurements and grain size analysis are invasive and relatively expensive. A geoelectric investigation involving vertical electrical sounding was carried in parts of Enugu town, Enugu state, Nigeria. The survey was aimed at extrapolating the result of pumping tests over an area. Using the Dar Zarrouk parameter, a β constant of 0.32 was found to translate resistivity to transmissivity with clay content as the primary factor controlling the hydraulic conductivity. Results of the study show a strong correlation between aquifer transmissivity and longitudinal conductance (R2 = 0.82). Estimation of aquifer transmissivity values based on the results of the resistivity measurements also made it possible to demarcate area with good groundwater potential in parts of Enugu town, Nigeria.展开更多
Influence radius of a pumping well is a crucial parameter for hydrogeologists and engineers. Knowing the radius of influence for a designed drawdown enables one to calculate the pumping rate required to layout a proje...Influence radius of a pumping well is a crucial parameter for hydrogeologists and engineers. Knowing the radius of influence for a designed drawdown enables one to calculate the pumping rate required to layout a project foundation that may need lowering of groundwater level to a certain depth due to dewatering operation. In addition, this is important for hydrogeologists to determine ground water contamination flow paths and contributing recharge area for domestic water supply and aquifer management purposes. Empirical formulas that usually neglect vital parameters to determine the influence radius accurately have been traditionally utilized due to lack of adequate methods. In this study, a physically based method, which incorporates aquifer hydraulic gradient for determining the influence radius of a pumping well in steady-state flow condition, was developed. It utilizes Darcy and Dupuit laws to calculate the influence radius, where Darcy’s law and Dupuit equation, in steady-state condition, represent the inflow and the outflow of the pumping well, respectively. In an untraditional manner, this method can be also used to determine aquifer hydraulic conductivity as an alternative to other pumping test methods with high degree of accuracy. The developed method is easy to use;where a simple mathematical calculator may be used to calculate the influence radius and the pumping rate or hydraulic conductivity. By comparing the results from this method with the MODFLOW numerical model outputs with different simulated scenarios, it is realized that this method is much superior and more advantageous than other commonly used empirical methods.展开更多
Through the reversible isomerization of trans-cis-trans under the linear polarization light, the molecules of azo materials have the same tropism which is vertical to the polarization of light. This means that azo mat...Through the reversible isomerization of trans-cis-trans under the linear polarization light, the molecules of azo materials have the same tropism which is vertical to the polarization of light. This means that azo materials have photo-induced birefringence which is related to optical power and polarization angle of the light. Based on the photo-induced birefringence of azo materials, we design a new type of optically pumped semiconductor vertical external cavity surface emitting laser （OPS-VECSEL） which can control the polarization and frequency of the ejection laser. The functional molecules of azo materials are [3-azo- （4＇nitro）]- （9-ethyl）-carbazole （ANECz）.展开更多
Aquifers derived from the crystalline basement rocks for parts of Sanga Local Government area of Kaduna State, Nigeria consist of clay, silt, sand, gravel and laterite materials which may be in various proportions. Us...Aquifers derived from the crystalline basement rocks for parts of Sanga Local Government area of Kaduna State, Nigeria consist of clay, silt, sand, gravel and laterite materials which may be in various proportions. Using Cooper-Jacobs non-equilibrium graphical method, the hydraulic properties were estimated from pumping test data of 18 boreholes. Conductivity varies from 1.02 × 10<sup>﹣2</sup> m/s to 4.07 × 10<sup>﹣2</sup> m/s and transmissivity varies from 1.14 × 10<sup>﹣1</sup> m<sup>2</sup>/s to 4.40 × 10<sup>﹣1</sup> m<sup>2</sup>/s. The values of specific capacity range between 1.03 × 10<sup>﹣1</sup> m<sup>2</sup>/s/m and 9.00 × 10<sup>﹣2</sup> m<sup>2</sup>/s/m, and these values indicate that the aquifers in the area have low to moderate ground water potentials. The low yield range of between 0.45 l/s and 1.00 l/s recorded in the area shows the heterogeneous and anisotropy nature of the basement aquifer system in terms of groundwater discharge. On the average, the boreholes assessed have potentials to sustain local to regional supply provided the best drilling method and materials are used and well completion properly done.展开更多
Spin pumping at the Co2FeAl0.5Si0.5/Pt and Pt/Co2FeAl0.5Si0.5 interfaces has been studied by ferromagnetic resonance technology(FMR). The spin mixing conductance of the Co2FeAl0.5Si0.5/Pt and Pt/Co2FeAl0.5Si0.5 interf...Spin pumping at the Co2FeAl0.5Si0.5/Pt and Pt/Co2FeAl0.5Si0.5 interfaces has been studied by ferromagnetic resonance technology(FMR). The spin mixing conductance of the Co2FeAl0.5Si0.5/Pt and Pt/Co2FeAl0.5Si0.5 interfaces was determined to be 3.7×1019m 2and 2.1×1019m 2 by comparing the Gilbert damping in a Co2FeAl0.5Si0.5single film, Co2FeAl0.5Si0.5/Pt bilayer film and a Pt/Co2FeAl0.5Si0.5/Pt trilayer film. Spin pumping is more efficient in the Co2FeAl0.5Si0.5/Pt bilayer film than in permalloy/Pt bilayer film.展开更多
The present study has been undertaken to depict spatial distribution of different aquifer parameters in the eastern part of Kushtia district through a detailed hydrogeological survey. For this investigation, 119 litho...The present study has been undertaken to depict spatial distribution of different aquifer parameters in the eastern part of Kushtia district through a detailed hydrogeological survey. For this investigation, 119 lithologs and 92 pumping test data have been used. These data have been processed, analyzed, interpreted and krigged for the spatial assessment of the aquifer properties viz. transmissivity, hydraulic conductivity, hydraulic diffusivity, specific yield, radius of influence, and specific drawdown. It is seen from the investigation that the transmissivity and hydraulic conductivity values obtained from the pumping tests of the wells are varying from 1811 m<sup>2</sup>/day to 2568 m<sup>2</sup>/day and 32.5 m/day and 61.5 m/day respectively, the hydraulic diffusivity being ranging from 181,143 m<sup>2</sup>/day to 256,788 m<sup>2</sup>/day. The estimated specific yield of 17.97% - 23.46% supports that the area is dominated with coarse grained sands. This study reveals that the distribution of deep tube wells in the area are not within the radius of influence (638 - 760 m) each other, but few shallow and hand tube wells existed within the radius of influence. The estimated specific draw down is varying from 57 m/cumec to 126.1 m/cumec. From the overall analysis, it is found that the area is favorable for groundwater exploration.展开更多
In order to investigate the influence of correlation scale error on the inversion precision of the hydraulic conductivity of the aquifer,the successive linear estimator(SLE)was used to invert the hydraulic conductivit...In order to investigate the influence of correlation scale error on the inversion precision of the hydraulic conductivity of the aquifer,the successive linear estimator(SLE)was used to invert the hydraulic conductivity field of a heterogeneous aquifer based on synthetic experiments.By increasing the numbers of observation wells and pumping tests,we analyzed the difference between the estimated and true values of hydraulic conductivity with different correlation scale errors.The relationships between the observation well number and the error in inversion results,and between the pumping test number and the error in inversion results were investigated.The results show that,if the amount of observed head data is insufficient,there will be errors in inversion results with changing correlation scale.Due to the existence of correlation scale error,the improvement of inversion precision gradually slows down with the increase of the amount of observed head data,which indicates that too much observed head data causes data redundancy.Therefore,for the synthetic experiments described in this paper,the observation well number should be less than 41,the pumping test number should be less than 17,and a more suitable method should be selected according to the precision requirements of specific situations in practical engineering.展开更多
基金supported by High Energy Photon Source(HEPS),a major national science and technology infrastructure,and Xie Jialin Research Fund(No.E2546HU210)National Development and Reform Commission(2017)No.2173。
文摘Introduction Non-evaporable getter is now widely employed in many accelerators to mitigate the resistive-wall effect of the Ti-Zr-V getter coated vacuum chambers in the next generation accelerators.Methods and discussions Quaternary Ti-Zr-V-Cu getter films were deposited by direct current(DC)magnetron sputtering.The DC/high frequency impedance and activation kinetics were investigated by four-probes/waveguide methods and in situ synchrotron radiation photoelectron spectroscopy(SRPES).Conclusions Compared to Ti-Zr-V films,Ti-Zr-V-Cu films showed better conductivity,which is beneficial to eliminate the resistive-wall effect.However,its initial activation temperature is above 200℃,and it needs to be activated at a higher temperature to achieve the required pumping performance.
文摘Many investigation techniques are commonly employed with the aim of estimating the spatial distribution of transmissivity. Unfortunately, the conventional methods for the determination of hydraulic parameters such as pumping tests, permeameter measurements and grain size analysis are invasive and relatively expensive. A geoelectric investigation involving vertical electrical sounding was carried in parts of Enugu town, Enugu state, Nigeria. The survey was aimed at extrapolating the result of pumping tests over an area. Using the Dar Zarrouk parameter, a β constant of 0.32 was found to translate resistivity to transmissivity with clay content as the primary factor controlling the hydraulic conductivity. Results of the study show a strong correlation between aquifer transmissivity and longitudinal conductance (R2 = 0.82). Estimation of aquifer transmissivity values based on the results of the resistivity measurements also made it possible to demarcate area with good groundwater potential in parts of Enugu town, Nigeria.
文摘Influence radius of a pumping well is a crucial parameter for hydrogeologists and engineers. Knowing the radius of influence for a designed drawdown enables one to calculate the pumping rate required to layout a project foundation that may need lowering of groundwater level to a certain depth due to dewatering operation. In addition, this is important for hydrogeologists to determine ground water contamination flow paths and contributing recharge area for domestic water supply and aquifer management purposes. Empirical formulas that usually neglect vital parameters to determine the influence radius accurately have been traditionally utilized due to lack of adequate methods. In this study, a physically based method, which incorporates aquifer hydraulic gradient for determining the influence radius of a pumping well in steady-state flow condition, was developed. It utilizes Darcy and Dupuit laws to calculate the influence radius, where Darcy’s law and Dupuit equation, in steady-state condition, represent the inflow and the outflow of the pumping well, respectively. In an untraditional manner, this method can be also used to determine aquifer hydraulic conductivity as an alternative to other pumping test methods with high degree of accuracy. The developed method is easy to use;where a simple mathematical calculator may be used to calculate the influence radius and the pumping rate or hydraulic conductivity. By comparing the results from this method with the MODFLOW numerical model outputs with different simulated scenarios, it is realized that this method is much superior and more advantageous than other commonly used empirical methods.
文摘Through the reversible isomerization of trans-cis-trans under the linear polarization light, the molecules of azo materials have the same tropism which is vertical to the polarization of light. This means that azo materials have photo-induced birefringence which is related to optical power and polarization angle of the light. Based on the photo-induced birefringence of azo materials, we design a new type of optically pumped semiconductor vertical external cavity surface emitting laser （OPS-VECSEL） which can control the polarization and frequency of the ejection laser. The functional molecules of azo materials are [3-azo- （4＇nitro）]- （9-ethyl）-carbazole （ANECz）.
文摘Aquifers derived from the crystalline basement rocks for parts of Sanga Local Government area of Kaduna State, Nigeria consist of clay, silt, sand, gravel and laterite materials which may be in various proportions. Using Cooper-Jacobs non-equilibrium graphical method, the hydraulic properties were estimated from pumping test data of 18 boreholes. Conductivity varies from 1.02 × 10<sup>﹣2</sup> m/s to 4.07 × 10<sup>﹣2</sup> m/s and transmissivity varies from 1.14 × 10<sup>﹣1</sup> m<sup>2</sup>/s to 4.40 × 10<sup>﹣1</sup> m<sup>2</sup>/s. The values of specific capacity range between 1.03 × 10<sup>﹣1</sup> m<sup>2</sup>/s/m and 9.00 × 10<sup>﹣2</sup> m<sup>2</sup>/s/m, and these values indicate that the aquifers in the area have low to moderate ground water potentials. The low yield range of between 0.45 l/s and 1.00 l/s recorded in the area shows the heterogeneous and anisotropy nature of the basement aquifer system in terms of groundwater discharge. On the average, the boreholes assessed have potentials to sustain local to regional supply provided the best drilling method and materials are used and well completion properly done.
基金Project supported by the National Basic Research Program of China(Grant No.2012CB932702)the National Natural Science Foundation of China(Grant Nos.51271020,51071022,and 11174031)+2 种基金the Program for Changjiang Scholars and Innovative Research Team in University,China(PCSIRT)the Beijing Nova Program,China(Grant No.2011031)the Fundamental Research Funds for the Central Universities of Ministry of Education of China
文摘Spin pumping at the Co2FeAl0.5Si0.5/Pt and Pt/Co2FeAl0.5Si0.5 interfaces has been studied by ferromagnetic resonance technology(FMR). The spin mixing conductance of the Co2FeAl0.5Si0.5/Pt and Pt/Co2FeAl0.5Si0.5 interfaces was determined to be 3.7×1019m 2and 2.1×1019m 2 by comparing the Gilbert damping in a Co2FeAl0.5Si0.5single film, Co2FeAl0.5Si0.5/Pt bilayer film and a Pt/Co2FeAl0.5Si0.5/Pt trilayer film. Spin pumping is more efficient in the Co2FeAl0.5Si0.5/Pt bilayer film than in permalloy/Pt bilayer film.
文摘The present study has been undertaken to depict spatial distribution of different aquifer parameters in the eastern part of Kushtia district through a detailed hydrogeological survey. For this investigation, 119 lithologs and 92 pumping test data have been used. These data have been processed, analyzed, interpreted and krigged for the spatial assessment of the aquifer properties viz. transmissivity, hydraulic conductivity, hydraulic diffusivity, specific yield, radius of influence, and specific drawdown. It is seen from the investigation that the transmissivity and hydraulic conductivity values obtained from the pumping tests of the wells are varying from 1811 m<sup>2</sup>/day to 2568 m<sup>2</sup>/day and 32.5 m/day and 61.5 m/day respectively, the hydraulic diffusivity being ranging from 181,143 m<sup>2</sup>/day to 256,788 m<sup>2</sup>/day. The estimated specific yield of 17.97% - 23.46% supports that the area is dominated with coarse grained sands. This study reveals that the distribution of deep tube wells in the area are not within the radius of influence (638 - 760 m) each other, but few shallow and hand tube wells existed within the radius of influence. The estimated specific draw down is varying from 57 m/cumec to 126.1 m/cumec. From the overall analysis, it is found that the area is favorable for groundwater exploration.
基金This work was supported by the National Natural Science Foundation of China(Grants No.51879134 and 51569023)the First-class Discipline Construction Funding Project for the Ningxia University of China(Hydraulic Engineering)(Grant No.NXYLXK2017A03).
文摘In order to investigate the influence of correlation scale error on the inversion precision of the hydraulic conductivity of the aquifer,the successive linear estimator(SLE)was used to invert the hydraulic conductivity field of a heterogeneous aquifer based on synthetic experiments.By increasing the numbers of observation wells and pumping tests,we analyzed the difference between the estimated and true values of hydraulic conductivity with different correlation scale errors.The relationships between the observation well number and the error in inversion results,and between the pumping test number and the error in inversion results were investigated.The results show that,if the amount of observed head data is insufficient,there will be errors in inversion results with changing correlation scale.Due to the existence of correlation scale error,the improvement of inversion precision gradually slows down with the increase of the amount of observed head data,which indicates that too much observed head data causes data redundancy.Therefore,for the synthetic experiments described in this paper,the observation well number should be less than 41,the pumping test number should be less than 17,and a more suitable method should be selected according to the precision requirements of specific situations in practical engineering.
