High-resolution optical spectra of the zero age star HD77407 are analysed and its Li, C, O, Na, Mg, Al, Si, K, Ca, Sc, Ti, V, Co, Ni and Ba contents are determined using spectral synthesis method. The temperature of t...High-resolution optical spectra of the zero age star HD77407 are analysed and its Li, C, O, Na, Mg, Al, Si, K, Ca, Sc, Ti, V, Co, Ni and Ba contents are determined using spectral synthesis method. The temperature of the star is determined by fitting the Hα line wings. The parameters derived for this star are Teff=5900 K, log g=4.47 and [Fe/H] = ＋0.07. It is found that the derived iron content is slightly higher than what is given in the published literature. This star shows a relative overabundances of Ca and Ba, and underabundances of Na, V and Ni with respect to the solar mix. Activity of the star is indicated by the filled in Hα and Ca Ⅱ triplet line cores. It has been confirmed that our spectroscopic approach yields fairly reliable and consistent results for active stars.展开更多
针对免处理涂镀锌基系板材在钣金应用中焊接接头性能差、烧蚀发黑、焊缝及切口易生锈问题,研究了ZAM薄板的激光焊接性能,和焊接接头及切口的耐腐蚀补偿工艺。研究表明:采用激光自熔焊接1.2 mm ZAM薄板,预留0.1 mm对接间隙,并以10 L/min...针对免处理涂镀锌基系板材在钣金应用中焊接接头性能差、烧蚀发黑、焊缝及切口易生锈问题,研究了ZAM薄板的激光焊接性能,和焊接接头及切口的耐腐蚀补偿工艺。研究表明:采用激光自熔焊接1.2 mm ZAM薄板,预留0.1 mm对接间隙,并以10 L/min的流速充Ar防护,可获得较小的热影响区。焊接接头的正面焊缝成形轻微凹陷,反面熔合区烧蚀发黑,焊缝强度不低于母材强度。焊接接头正火区晶粒细化明显,熔合线的近焊缝区有贝氏体,远离熔合线的焊缝组织中有块状铁素体、片状珠光体及魏氏组织。焊接接头硬化明显,与母材相比,焊缝处硬度增大30%以上。同时发现,焊接接头及冲裁切口处失去涂镀层保护,仍具有一定的耐腐蚀能力。对焊接接头处冷镀锌处理,对切口处浸涂防锈油处理,其耐盐雾能力显著提升。最后展望了激光焊接免处理涂镀锌基系薄板在钣金制品中的应用前景。展开更多
As the first Islamic sacred city,the health security of drinking water in Mecca has been highly concerned since ancient time.As a unique potable water resource of Mecca,the health security of Bir Zam Zam has aroused t...As the first Islamic sacred city,the health security of drinking water in Mecca has been highly concerned since ancient time.As a unique potable water resource of Mecca,the health security of Bir Zam Zam has aroused the high attention of Muslims and related countries all over the world,which is closely related to the special status generated by the origin of the role in the sa’y ceremony of the hajj.Because of this,Zam Zam water is widely regarded as‘sacred water’and appears the phenomenon of reli-gious alienation in its health function.In 2013,Saudi Arabia launched a new Bir Zam Zam project to improve water quality by more scientific and technological means.Relevant tests found that its water quality could meet the potable water standards of the World Health Organisation and the American Public Health Association,but there were also voices of doubt from abroad,and Saudi Arabia also responded to this.With the advent of the post-pandemic era and the resumption of the hajj for Muslims outside Saudi Arabia in 2022,the consumption of Bir Zam Zam by pilgrims and Muslims will rise to high levels,inevitably leading to an upward risk to international health security.展开更多
基金the National Natural Science Foundation of China
文摘High-resolution optical spectra of the zero age star HD77407 are analysed and its Li, C, O, Na, Mg, Al, Si, K, Ca, Sc, Ti, V, Co, Ni and Ba contents are determined using spectral synthesis method. The temperature of the star is determined by fitting the Hα line wings. The parameters derived for this star are Teff=5900 K, log g=4.47 and [Fe/H] = ＋0.07. It is found that the derived iron content is slightly higher than what is given in the published literature. This star shows a relative overabundances of Ca and Ba, and underabundances of Na, V and Ni with respect to the solar mix. Activity of the star is indicated by the filled in Hα and Ca Ⅱ triplet line cores. It has been confirmed that our spectroscopic approach yields fairly reliable and consistent results for active stars.
文摘针对免处理涂镀锌基系板材在钣金应用中焊接接头性能差、烧蚀发黑、焊缝及切口易生锈问题,研究了ZAM薄板的激光焊接性能,和焊接接头及切口的耐腐蚀补偿工艺。研究表明:采用激光自熔焊接1.2 mm ZAM薄板,预留0.1 mm对接间隙,并以10 L/min的流速充Ar防护,可获得较小的热影响区。焊接接头的正面焊缝成形轻微凹陷,反面熔合区烧蚀发黑,焊缝强度不低于母材强度。焊接接头正火区晶粒细化明显,熔合线的近焊缝区有贝氏体,远离熔合线的焊缝组织中有块状铁素体、片状珠光体及魏氏组织。焊接接头硬化明显,与母材相比,焊缝处硬度增大30%以上。同时发现,焊接接头及冲裁切口处失去涂镀层保护,仍具有一定的耐腐蚀能力。对焊接接头处冷镀锌处理,对切口处浸涂防锈油处理,其耐盐雾能力显著提升。最后展望了激光焊接免处理涂镀锌基系薄板在钣金制品中的应用前景。
基金the major procject of Key Research Inititute at University,Chinese Ministry of Education[2022JDPA002].
文摘As the first Islamic sacred city,the health security of drinking water in Mecca has been highly concerned since ancient time.As a unique potable water resource of Mecca,the health security of Bir Zam Zam has aroused the high attention of Muslims and related countries all over the world,which is closely related to the special status generated by the origin of the role in the sa’y ceremony of the hajj.Because of this,Zam Zam water is widely regarded as‘sacred water’and appears the phenomenon of reli-gious alienation in its health function.In 2013,Saudi Arabia launched a new Bir Zam Zam project to improve water quality by more scientific and technological means.Relevant tests found that its water quality could meet the potable water standards of the World Health Organisation and the American Public Health Association,but there were also voices of doubt from abroad,and Saudi Arabia also responded to this.With the advent of the post-pandemic era and the resumption of the hajj for Muslims outside Saudi Arabia in 2022,the consumption of Bir Zam Zam by pilgrims and Muslims will rise to high levels,inevitably leading to an upward risk to international health security.
