This paper,in two installments,attempts to clarify the finer points in the similarities and differences in the usage of relative pronouns,who,that and which,while they are in relative clauses.They are illustrated and ...This paper,in two installments,attempts to clarify the finer points in the similarities and differences in the usage of relative pronouns,who,that and which,while they are in relative clauses.They are illustrated and justified with examples.The paper,through the comparison of the usages of who,that and which,has shown their similarities and differences from one another.It will enable us to master their usages and help us in studying relative clauses.展开更多
Multi-pass tandem gas metal arc welding(TGMAW) for Al 5083 alloy plates with 30 mm thickness is carried out to study its high efficiency and high quality. The welding process is evaluated by high-speed photographs and...Multi-pass tandem gas metal arc welding(TGMAW) for Al 5083 alloy plates with 30 mm thickness is carried out to study its high efficiency and high quality. The welding process is evaluated by high-speed photographs and electrical signals. The deposition rate and welding time are calculated to characterize the welding efficiency. The bead formation, porosity, microstructure and mechanical properties are tested and analyzed. The results indicate that though arc deflection occurs due to the electromagnetic interference between two arcs during TGMAW process, it does not affect the welding process stability significantly. The deposition rate and welding time of TGMAW process are about 15 g/min larger and about 16.7% less than those of gas metal arc welding(GMAW)process respectively, accompanied by the reduction of heat input. The TGMAW welded joint has less porosity and more refined microstructure to contribute to the improvement of mechanical properties(micro-hardness, tensile strength and ductility). It can be concluded that TGMAW process yields excellent performance of welded joint with improved welding efficiency, which makes it extremely practical during welding of thick plates.展开更多
文摘This paper,in two installments,attempts to clarify the finer points in the similarities and differences in the usage of relative pronouns,who,that and which,while they are in relative clauses.They are illustrated and justified with examples.The paper,through the comparison of the usages of who,that and which,has shown their similarities and differences from one another.It will enable us to master their usages and help us in studying relative clauses.
基金the National Natural Science Foundation of China(No.51475297)the Fund of the Ministry of Industry and Information Technology of China Under the Project of LNG Shipbuilding
文摘Multi-pass tandem gas metal arc welding(TGMAW) for Al 5083 alloy plates with 30 mm thickness is carried out to study its high efficiency and high quality. The welding process is evaluated by high-speed photographs and electrical signals. The deposition rate and welding time are calculated to characterize the welding efficiency. The bead formation, porosity, microstructure and mechanical properties are tested and analyzed. The results indicate that though arc deflection occurs due to the electromagnetic interference between two arcs during TGMAW process, it does not affect the welding process stability significantly. The deposition rate and welding time of TGMAW process are about 15 g/min larger and about 16.7% less than those of gas metal arc welding(GMAW)process respectively, accompanied by the reduction of heat input. The TGMAW welded joint has less porosity and more refined microstructure to contribute to the improvement of mechanical properties(micro-hardness, tensile strength and ductility). It can be concluded that TGMAW process yields excellent performance of welded joint with improved welding efficiency, which makes it extremely practical during welding of thick plates.
