The effects of rare earth Ce on the microstructure and mechanical properties of impure copper containing Pb were investigated using OM,SEM,EPMA,TEM and tensile testing.TEM and EDS analysis reveal that spherical CePb3 ...The effects of rare earth Ce on the microstructure and mechanical properties of impure copper containing Pb were investigated using OM,SEM,EPMA,TEM and tensile testing.TEM and EDS analysis reveal that spherical CePb3 particles form after Ce addition.CePb3 particles,with average size of^3.6μm,homogenously distribute in the Cu matrix.Due to small lattice misfit(~4.62%)with Cu matrix,CePb3 particles can act as effective nucleation sites beneficial to the grain refinement.Pb at grain boundaries seriously deteriorates the mechanical properties of Cu.The tensile strength and the elongation of Cu-0.1 Pb are decreased by 43.1%and 56.7%compared with those of pure copper,respectively.Ce can purify grain boundaries,cause the precipitation of CePb3 particles and refine grain sizes,which contribute to significant improvement of the mechanical properties of Cu.Compared with Cu-0.1Pb,the tensile strength(179 MPa)and the elongation(38.5%)of Cu-0.1Pb-0.3Ce are increased by 117.6%and 151.6%,respectively.展开更多
Based on the analysis of inner motive of industrial structure evolution in developed countries after Worm War II and the contribution of primary, secondary and tertiary industries to economic growth at similar economi...Based on the analysis of inner motive of industrial structure evolution in developed countries after Worm War II and the contribution of primary, secondary and tertiary industries to economic growth at similar economic development stage as China is, this paper argues that the rising proportion of tertiary industry in developed countries after World War II is mainly caused by the price hikes in tertiary industry. During a similar economic development stage as China is, the secondary industry in both the U.S. and Japan contributed more than 60% to economic growth, thus became the driving force in real sense. This paper analyzes the change of industrial structure after 1978 and points out the gap in industrial structure when calculated by fixed price and current year＇s price. From 1978 to 2009, China＇s industrial priority was mainly transferred from primary industry to tertiary industry infixed price terms but shifted from primary industry to secondary industry in terms of current year＇s price. With a contribution rate of 68.8%, China＇s secondary industry is the chief driver of economic growth since 1978 and will continue to be so till 2020. As the tertiary industry can hardly be such a driver, the increase in tertiary industry proportion is insignificant to real economic growth, so it is not necessary for China to put tertiary industry as the starting point of industrial upgrading. Instead, China shall try every means to improve the international competitiveness of secondary industry so as to promote the qualitative and rapid growth of Chinese economy by tapping into its quality-oriented demographic dividend.展开更多
Electro-thermal accelerator uses high-voltage arc energy to heat the actuating medium, it being made from low-molecular weight material. Projectile acceleration is achieved by expansion of the actuating medium. Numeri...Electro-thermal accelerator uses high-voltage arc energy to heat the actuating medium, it being made from low-molecular weight material. Projectile acceleration is achieved by expansion of the actuating medium. Numerical method for calculating interior ballistics uses Lagrangian coordinates there the conservation of momentum and the energy balance are solved. A statement of the energy balance reflects the second law of thermodynamics. Lagrangian different grid and scheme for numerical calculation were used. Fully explicit scheme was employed. The solving includes two stability conditions： Courant and shock （artificial viscosity）. Numerical results were compared with the experimental research for pressure in the barrel in electro-thermal accelerator.展开更多
In this study, a complex multi-body structure was proposed, and the mechanism for the dynamic response of the structure under explosive driving was investigated by using the Lagrange equations of the second kind. An i...In this study, a complex multi-body structure was proposed, and the mechanism for the dynamic response of the structure under explosive driving was investigated by using the Lagrange equations of the second kind. An initial value subject to explosion loading was analyzed to develop the theoretical model of the dynamic response, and the centroid trajectory of three different structural shapes was solved. To verify the accuracy of the theoretical model, numerical simulation via finite element analysis within LS-DYNA and a dynamic experiment were conducted, and the consistent dynamic response process of the multi-body structure was obtained. In addition, the dynamic response time of the multi-body structure under different explosion loading conditions was calculated by the theoretical model, numerical simulation, and experimental investigation. It was found that the increased opening charge mass reduces the dynamic response time.展开更多
We discuss the stationarity of generator G for gauge symmetries in two directions.One is to the motion equations defined by total Hamiltonian H T,and gives that the number of the independent coefficients in the genera...We discuss the stationarity of generator G for gauge symmetries in two directions.One is to the motion equations defined by total Hamiltonian H T,and gives that the number of the independent coefficients in the generator G is not greater than the number of the primary first-class constraints,and the number of Noether conserved charges is not greater than that of the primary first-class constraints,too.The other is to the variances of canonical variables deduced from the generator G,and gives the variances of Lagrangian multipliers contained in extended Hamiltonian H E.And a second-class constraint generated by a first-class constraint may imply a new first-class constraint which can be combined by introducing other second-class constraints.Finally,we supply two examples.One with three first-class constraints(two is primary and one is secondary) has two Noether conserved charges,and the secondary first-class constraint is combined by three second-class constraints which are a secondary and two primary second-class constraints.The other with two first-class constraints(one is primary and one is secondary) has one Noehter conserved charge.展开更多
We present a new calorimetric method for measuring alternative current(AC)losses of high-temperature superconducting(HTS)tapes by optical fiber Bragg grating(FBG),which is particularly well suited for the AC loss meas...We present a new calorimetric method for measuring alternative current(AC)losses of high-temperature superconducting(HTS)tapes by optical fiber Bragg grating(FBG),which is particularly well suited for the AC loss measurement of Re BCO wires,so-called the second generation(2G)HTS wires.Compared with conventional calorimetric methods,the suggested method is both free of electromagnetic disturbance,magnetic field,and fast as well as simple.Self-field AC losses are measured by the optical FBG method and the conventional lock-in-amplifier(LIA)technique,respectively.The results show that the measured AC loss is in good agreement with those measured by the electric method,thus the presented calorimetric method would be available for measuring the AC loss of 2G wire and is expected to be generalized for the measurement of AC loss or thermal performances of HTS bulk.展开更多
基金Projects(ZR2018MEE005,ZR2018MEE016)supported by the Natural Science Foundation of Shandong Province,ChinaProject(J18KA059)supported by the Higher Educational Science and Technology Program of Shandong Province,ChinaProject(HJ16B01)supported by the Doctoral Fund of Yantai University,China。
文摘The effects of rare earth Ce on the microstructure and mechanical properties of impure copper containing Pb were investigated using OM,SEM,EPMA,TEM and tensile testing.TEM and EDS analysis reveal that spherical CePb3 particles form after Ce addition.CePb3 particles,with average size of^3.6μm,homogenously distribute in the Cu matrix.Due to small lattice misfit(~4.62%)with Cu matrix,CePb3 particles can act as effective nucleation sites beneficial to the grain refinement.Pb at grain boundaries seriously deteriorates the mechanical properties of Cu.The tensile strength and the elongation of Cu-0.1 Pb are decreased by 43.1%and 56.7%compared with those of pure copper,respectively.Ce can purify grain boundaries,cause the precipitation of CePb3 particles and refine grain sizes,which contribute to significant improvement of the mechanical properties of Cu.Compared with Cu-0.1Pb,the tensile strength(179 MPa)and the elongation(38.5%)of Cu-0.1Pb-0.3Ce are increased by 117.6%and 151.6%,respectively.
文摘Based on the analysis of inner motive of industrial structure evolution in developed countries after Worm War II and the contribution of primary, secondary and tertiary industries to economic growth at similar economic development stage as China is, this paper argues that the rising proportion of tertiary industry in developed countries after World War II is mainly caused by the price hikes in tertiary industry. During a similar economic development stage as China is, the secondary industry in both the U.S. and Japan contributed more than 60% to economic growth, thus became the driving force in real sense. This paper analyzes the change of industrial structure after 1978 and points out the gap in industrial structure when calculated by fixed price and current year＇s price. From 1978 to 2009, China＇s industrial priority was mainly transferred from primary industry to tertiary industry infixed price terms but shifted from primary industry to secondary industry in terms of current year＇s price. With a contribution rate of 68.8%, China＇s secondary industry is the chief driver of economic growth since 1978 and will continue to be so till 2020. As the tertiary industry can hardly be such a driver, the increase in tertiary industry proportion is insignificant to real economic growth, so it is not necessary for China to put tertiary industry as the starting point of industrial upgrading. Instead, China shall try every means to improve the international competitiveness of secondary industry so as to promote the qualitative and rapid growth of Chinese economy by tapping into its quality-oriented demographic dividend.
文摘Electro-thermal accelerator uses high-voltage arc energy to heat the actuating medium, it being made from low-molecular weight material. Projectile acceleration is achieved by expansion of the actuating medium. Numerical method for calculating interior ballistics uses Lagrangian coordinates there the conservation of momentum and the energy balance are solved. A statement of the energy balance reflects the second law of thermodynamics. Lagrangian different grid and scheme for numerical calculation were used. Fully explicit scheme was employed. The solving includes two stability conditions： Courant and shock （artificial viscosity）. Numerical results were compared with the experimental research for pressure in the barrel in electro-thermal accelerator.
基金supported by the National Natural Science Foundation of China(Grant Nos.11372046,11521062)
文摘In this study, a complex multi-body structure was proposed, and the mechanism for the dynamic response of the structure under explosive driving was investigated by using the Lagrange equations of the second kind. An initial value subject to explosion loading was analyzed to develop the theoretical model of the dynamic response, and the centroid trajectory of three different structural shapes was solved. To verify the accuracy of the theoretical model, numerical simulation via finite element analysis within LS-DYNA and a dynamic experiment were conducted, and the consistent dynamic response process of the multi-body structure was obtained. In addition, the dynamic response time of the multi-body structure under different explosion loading conditions was calculated by the theoretical model, numerical simulation, and experimental investigation. It was found that the increased opening charge mass reduces the dynamic response time.
基金Supported by National Natural Science Foundation of China under Grant Nos.11047020 and 11047173Natural Science Foundation of Shandong Province,China under Grant Nos.ZR2011AM019,ZR2010AQ025,BS2010DS006,and Y200814Scientific and Technological Development Projection of Shandong Province,China under Grant No.J08LI56
文摘We discuss the stationarity of generator G for gauge symmetries in two directions.One is to the motion equations defined by total Hamiltonian H T,and gives that the number of the independent coefficients in the generator G is not greater than the number of the primary first-class constraints,and the number of Noether conserved charges is not greater than that of the primary first-class constraints,too.The other is to the variances of canonical variables deduced from the generator G,and gives the variances of Lagrangian multipliers contained in extended Hamiltonian H E.And a second-class constraint generated by a first-class constraint may imply a new first-class constraint which can be combined by introducing other second-class constraints.Finally,we supply two examples.One with three first-class constraints(two is primary and one is secondary) has two Noether conserved charges,and the secondary first-class constraint is combined by three second-class constraints which are a secondary and two primary second-class constraints.The other with two first-class constraints(one is primary and one is secondary) has one Noehter conserved charge.
基金supported by the National Natural Science Foundation of China(Grant No.51477053)the Beijing Education Commissions(Grant No.GJ2013009)
文摘We present a new calorimetric method for measuring alternative current(AC)losses of high-temperature superconducting(HTS)tapes by optical fiber Bragg grating(FBG),which is particularly well suited for the AC loss measurement of Re BCO wires,so-called the second generation(2G)HTS wires.Compared with conventional calorimetric methods,the suggested method is both free of electromagnetic disturbance,magnetic field,and fast as well as simple.Self-field AC losses are measured by the optical FBG method and the conventional lock-in-amplifier(LIA)technique,respectively.The results show that the measured AC loss is in good agreement with those measured by the electric method,thus the presented calorimetric method would be available for measuring the AC loss of 2G wire and is expected to be generalized for the measurement of AC loss or thermal performances of HTS bulk.
