根据砝码磁性参数的测量原理,针对磁性测量中示值稳定性的影响量进行分析,提出影响砝码磁性参数测量中示值稳定性的关键影响量.采用最大称量5.1 g、分辨率0.1μg的磁化率计进行砝码磁性测量,测量过程中分别同步测试振动的变化和环境磁...根据砝码磁性参数的测量原理,针对磁性测量中示值稳定性的影响量进行分析,提出影响砝码磁性参数测量中示值稳定性的关键影响量.采用最大称量5.1 g、分辨率0.1μg的磁化率计进行砝码磁性测量,测量过程中分别同步测试振动的变化和环境磁场的变化,通过实验数据分析,验证了环境磁场的波动是影响砝码磁性测量的关键影响量.Abstract：According to the measurement principle of weight magnetic parameter, the influence of reading stability for measuring magnetism is analyzed, and the key influence of reading stability is presented in the measurement process. The magnetism of weight is measured by the magnetic susceptometer with capacity of 5.1 g and resolution of O. 1 μg. At the same time the change of environmental vibration in the laboratory and the fluctuating of ambient magnetic field are measured respectively. The experimental results show the fluctuating of ambient magnetic field that is the key influence of weight magnetism measurement.展开更多
Desulfurization experiments of CuO, γ-Al2O3 and CuO/γ-Al2O3 were made in simulated flue gas by means of thermogravimetric analysis. It is found that reaction activities of CuO supported on γ-Al2O3 could be highly i...Desulfurization experiments of CuO, γ-Al2O3 and CuO/γ-Al2O3 were made in simulated flue gas by means of thermogravimetric analysis. It is found that reaction activities of CuO supported on γ-Al2O3 could be highly improved. Desulfurization kinetics of CuO/γ-Al2O3 was studied in the temperature range of 250 °C-400 °C and SO2 concentration of 0.1%-0.9%. The experimental data were tested and compared with kinetics models of volume reaction model(VRM), grain size model(GSM), random pore model(RPM) and pore-blocking model(PBM). Correlation analysis shows that VRM and RPM models do not fit experimental data well. GSM contradicts with the changes in the physical and chemical properties of Cu O/γ-Al2O3 as the desulfurization proceeds. It is found that PBM is consistent with the change of pore structure of CuO/γ-Al2O3 sorbent during desulfurization process and predicts the conversion-time curves of the sorbent well. Meanwhile, kinetics parameters are obtained and discussed.展开更多
The cost and safety of geotechnical engineering are highly depending on the accuracy of soil shear strength parameters.There are three methods often used to estimate soil shear strength parameters,i.e.,moment method,3...The cost and safety of geotechnical engineering are highly depending on the accuracy of soil shear strength parameters.There are three methods often used to estimate soil shear strength parameters,i.e.,moment method,3-sigma rule and linear regression method.In this study,the accuracy of these three methods is compared.Traditional linear regression method(LRM)can only offer the mean of shear strength parameters.Some engineers misuse the standard error of shear strength indexes as the standard deviations.Such misuse may highly underestimate the uncertainty and induce high risk to the geotechnical design.A modified LRM is proposed to determine both the mean and variance of shear strength parameters.The moment method,three-sigma rule and LRM are used to analyze the tri-axial test data in Xiaolangdi Hydraulic Project and three numerical shear strength tests.The results demonstrate that:1)The modified LRM can offer the most accurate estimation to shear strength parameters;2)A dimensionless formula is much preferred in LRM rather than a dimensional formula.The stress ratio formula is much better than stress relation in the shear strength parameter analysis.The proposed method is applicable to shear strength parameter analysis for tri-axial test data,direct shear test and the un-drained shear strength test of stratified clay.展开更多
文摘根据砝码磁性参数的测量原理,针对磁性测量中示值稳定性的影响量进行分析,提出影响砝码磁性参数测量中示值稳定性的关键影响量.采用最大称量5.1 g、分辨率0.1μg的磁化率计进行砝码磁性测量,测量过程中分别同步测试振动的变化和环境磁场的变化,通过实验数据分析,验证了环境磁场的波动是影响砝码磁性测量的关键影响量.Abstract：According to the measurement principle of weight magnetic parameter, the influence of reading stability for measuring magnetism is analyzed, and the key influence of reading stability is presented in the measurement process. The magnetism of weight is measured by the magnetic susceptometer with capacity of 5.1 g and resolution of O. 1 μg. At the same time the change of environmental vibration in the laboratory and the fluctuating of ambient magnetic field are measured respectively. The experimental results show the fluctuating of ambient magnetic field that is the key influence of weight magnetism measurement.
基金Projects(51264023,51364020,U1202271)supported by the National Natural Science Foundation of ChinaProject(IRT1250)supported by the Program for Innovative Research Team in University of Ministry of Education of ChinaProject(2014HA003)supported by the Yunnan Province Science and Technology Talents Program,China
文摘Desulfurization experiments of CuO, γ-Al2O3 and CuO/γ-Al2O3 were made in simulated flue gas by means of thermogravimetric analysis. It is found that reaction activities of CuO supported on γ-Al2O3 could be highly improved. Desulfurization kinetics of CuO/γ-Al2O3 was studied in the temperature range of 250 °C-400 °C and SO2 concentration of 0.1%-0.9%. The experimental data were tested and compared with kinetics models of volume reaction model(VRM), grain size model(GSM), random pore model(RPM) and pore-blocking model(PBM). Correlation analysis shows that VRM and RPM models do not fit experimental data well. GSM contradicts with the changes in the physical and chemical properties of Cu O/γ-Al2O3 as the desulfurization proceeds. It is found that PBM is consistent with the change of pore structure of CuO/γ-Al2O3 sorbent during desulfurization process and predicts the conversion-time curves of the sorbent well. Meanwhile, kinetics parameters are obtained and discussed.
基金Project(2017YFC0404803) supported by the National Key Research and Development Program of ChinaProject(51678040) supported by the National Natural Science Foundation of ChinaProject(8192034) supported by the Beijing Municipal Natural Science Foundation,China
文摘The cost and safety of geotechnical engineering are highly depending on the accuracy of soil shear strength parameters.There are three methods often used to estimate soil shear strength parameters,i.e.,moment method,3-sigma rule and linear regression method.In this study,the accuracy of these three methods is compared.Traditional linear regression method(LRM)can only offer the mean of shear strength parameters.Some engineers misuse the standard error of shear strength indexes as the standard deviations.Such misuse may highly underestimate the uncertainty and induce high risk to the geotechnical design.A modified LRM is proposed to determine both the mean and variance of shear strength parameters.The moment method,three-sigma rule and LRM are used to analyze the tri-axial test data in Xiaolangdi Hydraulic Project and three numerical shear strength tests.The results demonstrate that:1)The modified LRM can offer the most accurate estimation to shear strength parameters;2)A dimensionless formula is much preferred in LRM rather than a dimensional formula.The stress ratio formula is much better than stress relation in the shear strength parameter analysis.The proposed method is applicable to shear strength parameter analysis for tri-axial test data,direct shear test and the un-drained shear strength test of stratified clay.
