This study systematically investigates the effects of Al content on the microstructure,tensile properties,and high-cycle fatigue behavior of extruded Mg-xAl-Zn-Ca-Y(SENx)alloys.The results reveal that all extruded all...This study systematically investigates the effects of Al content on the microstructure,tensile properties,and high-cycle fatigue behavior of extruded Mg-xAl-Zn-Ca-Y(SENx)alloys.The results reveal that all extruded alloys exhibit fully recrystallized microstructures with undissolved second-phase particles enriched with Ca and Y.The average grain size varies non-monotonically with Al content due to the competing effects of recrystallization kinetics,solute drag,and particle band distribution.As Al content increases,tensile strength increases,while ductility decreases.Notably,despite its relatively coarse grain structure,the SEN9 alloy exhibits significantly higher yield strength than the SEN6 alloy.This improvement is mainly attributed to additional precipitation strengthening from fine Mg_(17)Al_(12)discontinuous precipitates formed along grain boundaries.Meanwhile,the reduced elongation observed in the SEN9 and SEN11 alloys is attributed to premature fracture at coarse Mg_(17)(Al,Zn,Ca)_(12)particle bands aligned along the extrusion direction.From the SEN1 to SEN9 alloys,the fatigue strength(FS)increases approximately linearly with ultimate tensile strength(UTS),reaching 170 MPa.However,this FS-UTS proportionality fails in the SEN11 alloy,where FS falls to 120 MPa despite the highest UTS.This deviation from the FS-UTS correlation that is observed for the lower-Al-content alloys is attributed to the clustered distribution of coarse Mg_(17)(Al,Zn,Ca)_(12)particles in the SEN11 alloy,which promotes early crack initiation under cyclic loading.These findings emphasize the importance of controlled Al addition in enhancing both strength and fatigue resistance while also highlighting the adverse effects of excessive Al content owing to microstructural embrittlement.展开更多
In the helicopter transmission systems, it is important to monitor and track the tooth damage evolution using lots of sensors and detection methods. This paper develops a novel approach for sensor selection based on p...In the helicopter transmission systems, it is important to monitor and track the tooth damage evolution using lots of sensors and detection methods. This paper develops a novel approach for sensor selection based on physical model and sensitivity analysis. Firstly, a physical model of tooth damage and mesh stiffness is built. Secondly, some effective condition indicators （Cls） are presented, and the optimal Cls set is selected by comparing their test statistics according to Mann-Kendall test. Afterwards, the selected CIs are used to generate a health indicator （HI） through sen slop estimator. Then, the sensors are selected according to the monotonic relevance and sensitivity to the damage levels. Finally, the proposed method is verified by the simulation and experimental data. The results show that the approach can provide a guide for health monitor- ing of helicopter transmission systems, and it is effective to reduce the test cost and improve the system＇s reliability.展开更多
2000年意大利学者Primi等从1名感染HIV的毒瘾者血清中分离到一株单链DNA病毒,以该病人的姓名第一个字母命名为SEN病毒(SENV)。该病毒有8个成员,分别命名为SENV-A～H。 SENV属于TTV相关病毒的超级家族(superfamily of TTV-related viruse...2000年意大利学者Primi等从1名感染HIV的毒瘾者血清中分离到一株单链DNA病毒,以该病人的姓名第一个字母命名为SEN病毒(SENV)。该病毒有8个成员,分别命名为SENV-A～H。 SENV属于TTV相关病毒的超级家族(superfamily of TTV-related viruses),是小的、很可能是无包膜的单链环状DNA病毒。对8株SENV、6株TTV原型株、7株TTV变异株(SANBAN、TUSO1、展开更多
According to the published nucleotide sequence of SEN virus genome,specific primers were designed and synthesizedFrom the serum of a Chinese patient with non-A-E hepatitis,two long fragments(totally 3175bp) spanning...According to the published nucleotide sequence of SEN virus genome,specific primers were designed and synthesizedFrom the serum of a Chinese patient with non-A-E hepatitis,two long fragments(totally 3175bp) spanning the complete coding region of SENV-D variant gene were amplified by semi-nested PCRThe amplified fragments were cloned and sequencedThe nucleotide sequence homology of this Chinese strain with SENV-D(AX025730),SENV-D(AB059352) and TTV(AB028668) were 90%,88% and 91% respectivelyThe protein encoded by ORF1 has two putative conserved sequence motifs relating to the replication of the virus and,besides,a conserved ATP/GTP-binding motif and several highly conserved protein kinase phosphorylation展开更多
基金supported by the Materials and Components Technology Development Program(No.20024843)funded by the Ministry of Trade,Industry&Energy(MOTIE,South Korea)the National Research Foundation of Korea(NRF)grant funded by the Korea government(MSIT)(No.RS-2024-00450561).
文摘This study systematically investigates the effects of Al content on the microstructure,tensile properties,and high-cycle fatigue behavior of extruded Mg-xAl-Zn-Ca-Y(SENx)alloys.The results reveal that all extruded alloys exhibit fully recrystallized microstructures with undissolved second-phase particles enriched with Ca and Y.The average grain size varies non-monotonically with Al content due to the competing effects of recrystallization kinetics,solute drag,and particle band distribution.As Al content increases,tensile strength increases,while ductility decreases.Notably,despite its relatively coarse grain structure,the SEN9 alloy exhibits significantly higher yield strength than the SEN6 alloy.This improvement is mainly attributed to additional precipitation strengthening from fine Mg_(17)Al_(12)discontinuous precipitates formed along grain boundaries.Meanwhile,the reduced elongation observed in the SEN9 and SEN11 alloys is attributed to premature fracture at coarse Mg_(17)(Al,Zn,Ca)_(12)particle bands aligned along the extrusion direction.From the SEN1 to SEN9 alloys,the fatigue strength(FS)increases approximately linearly with ultimate tensile strength(UTS),reaching 170 MPa.However,this FS-UTS proportionality fails in the SEN11 alloy,where FS falls to 120 MPa despite the highest UTS.This deviation from the FS-UTS correlation that is observed for the lower-Al-content alloys is attributed to the clustered distribution of coarse Mg_(17)(Al,Zn,Ca)_(12)particles in the SEN11 alloy,which promotes early crack initiation under cyclic loading.These findings emphasize the importance of controlled Al addition in enhancing both strength and fatigue resistance while also highlighting the adverse effects of excessive Al content owing to microstructural embrittlement.
基金supported by the National Natural Science Foundation of China (No. 51175502)
文摘In the helicopter transmission systems, it is important to monitor and track the tooth damage evolution using lots of sensors and detection methods. This paper develops a novel approach for sensor selection based on physical model and sensitivity analysis. Firstly, a physical model of tooth damage and mesh stiffness is built. Secondly, some effective condition indicators （Cls） are presented, and the optimal Cls set is selected by comparing their test statistics according to Mann-Kendall test. Afterwards, the selected CIs are used to generate a health indicator （HI） through sen slop estimator. Then, the sensors are selected according to the monotonic relevance and sensitivity to the damage levels. Finally, the proposed method is verified by the simulation and experimental data. The results show that the approach can provide a guide for health monitor- ing of helicopter transmission systems, and it is effective to reduce the test cost and improve the system＇s reliability.
文摘2000年意大利学者Primi等从1名感染HIV的毒瘾者血清中分离到一株单链DNA病毒,以该病人的姓名第一个字母命名为SEN病毒(SENV)。该病毒有8个成员,分别命名为SENV-A～H。 SENV属于TTV相关病毒的超级家族(superfamily of TTV-related viruses),是小的、很可能是无包膜的单链环状DNA病毒。对8株SENV、6株TTV原型株、7株TTV变异株(SANBAN、TUSO1、
文摘According to the published nucleotide sequence of SEN virus genome,specific primers were designed and synthesizedFrom the serum of a Chinese patient with non-A-E hepatitis,two long fragments(totally 3175bp) spanning the complete coding region of SENV-D variant gene were amplified by semi-nested PCRThe amplified fragments were cloned and sequencedThe nucleotide sequence homology of this Chinese strain with SENV-D(AX025730),SENV-D(AB059352) and TTV(AB028668) were 90%,88% and 91% respectivelyThe protein encoded by ORF1 has two putative conserved sequence motifs relating to the replication of the virus and,besides,a conserved ATP/GTP-binding motif and several highly conserved protein kinase phosphorylation
