This review article provides overall understanding of stainless,environment-friendly,and nonflammable Mg alloys(SEN alloys)recently developed at the Korea Institute of Materials Science.SEN alloys are produced by addi...This review article provides overall understanding of stainless,environment-friendly,and nonflammable Mg alloys(SEN alloys)recently developed at the Korea Institute of Materials Science.SEN alloys are produced by adding small amounts of Ca and Y(each<1 wt%)into commercial Mg–Al based alloys,resulting in exceptional ignition and corrosion resistances and impressive mechanical properties.Their main advantages of SEN alloys are as follows.(1)A dense multi-oxide layer of SEN alloys comprising MgO,CaO,and Y_(2)O_(3) impedes the outward dispersion of Mg vapor and the inward penetration of O_(2) during oxidation,thereby enhancing the oxidation and ignition resistances.(2)The presence of Ca-and Y-based second-phase particles in SEN alloys can enhance their corrosion resistance because Ca-containing particles prevent the spread of corrosion,and the replacement of Al-containing particles with less noble ones containing Y(e.g.,Al–Mn–Y or Al–Y particles)retards corrosion.(3)The addition of minor amounts of Ca and Y renders excellent mechanical properties due to improved strengthening effects.These enhanced properties are attributed to more pronounced dynamic recrystallization and grain refining behaviors caused by the second-phase particles during extrusion.(4)Despite the presence of various types of second-phase particles,the fatigue properties of SEN9 alloys are similar to those of commercial AZ91 alloys.(5)Simultaneous introduction of Ca and Y suppresses the formation of Mg17Al12 discontinuous precipitates during aging,leading to the enhanced elongation of aged SEN alloys.(6)Adding mischmetal into the SEN9 alloy leads to a six-fold enhancement in extrudability.Consequently,the studies conducted on SEN alloys demonstrate their excellent ignition and corrosion resistances and mechanical properties,which broaden the industrial applications of Mg alloys by addressing their inherent weaknesses.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)by the National Research Council of Science&Technology(NST)grant(No.CRC23011-000)funded by the Korea government(MSIT).
文摘This review article provides overall understanding of stainless,environment-friendly,and nonflammable Mg alloys(SEN alloys)recently developed at the Korea Institute of Materials Science.SEN alloys are produced by adding small amounts of Ca and Y(each<1 wt%)into commercial Mg–Al based alloys,resulting in exceptional ignition and corrosion resistances and impressive mechanical properties.Their main advantages of SEN alloys are as follows.(1)A dense multi-oxide layer of SEN alloys comprising MgO,CaO,and Y_(2)O_(3) impedes the outward dispersion of Mg vapor and the inward penetration of O_(2) during oxidation,thereby enhancing the oxidation and ignition resistances.(2)The presence of Ca-and Y-based second-phase particles in SEN alloys can enhance their corrosion resistance because Ca-containing particles prevent the spread of corrosion,and the replacement of Al-containing particles with less noble ones containing Y(e.g.,Al–Mn–Y or Al–Y particles)retards corrosion.(3)The addition of minor amounts of Ca and Y renders excellent mechanical properties due to improved strengthening effects.These enhanced properties are attributed to more pronounced dynamic recrystallization and grain refining behaviors caused by the second-phase particles during extrusion.(4)Despite the presence of various types of second-phase particles,the fatigue properties of SEN9 alloys are similar to those of commercial AZ91 alloys.(5)Simultaneous introduction of Ca and Y suppresses the formation of Mg17Al12 discontinuous precipitates during aging,leading to the enhanced elongation of aged SEN alloys.(6)Adding mischmetal into the SEN9 alloy leads to a six-fold enhancement in extrudability.Consequently,the studies conducted on SEN alloys demonstrate their excellent ignition and corrosion resistances and mechanical properties,which broaden the industrial applications of Mg alloys by addressing their inherent weaknesses.
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
