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地球自转速度随其年龄增长呈反比例单支双曲线衰减
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作者 吴海威 吴根耀 《地球科学前沿(汉斯)》 2019年第8期703-711,共9页
基于地球现今年龄、历时年龄与地球自转速度三者之间的关系提出地球自转速度表达式为:ωx=Aωq/(A-Tx)&#160;。该式显示地球自转速度(ωx)与地球历时年龄(A?Tx)呈反比例变化,即:随年龄增长地球自转速度减慢,相应地,地球的日长增加... 基于地球现今年龄、历时年龄与地球自转速度三者之间的关系提出地球自转速度表达式为:ωx=Aωq/(A-Tx)&#160;。该式显示地球自转速度(ωx)与地球历时年龄(A?Tx)呈反比例变化,即:随年龄增长地球自转速度减慢,相应地,地球的日长增加。该式所对应的图像为反比例函数在第一象限的单支双曲线,它可划分为三大区段(其第II区段可分为两个亚区段),分别对应了地球自转速度衰减的三个阶段,并可进一步区分出12个可能的地球自转速度半衰期。在距今4282Ma时,赤道自转速度已经衰减到第一宇宙速度之下,此为水成变质岩的年龄值上限。元古代半衰期和显生代半衰期的计算结果可得到化石生长线证据的验证,其余结果有待发现古老日长的可靠数据来校验。地球的历时年龄与该年龄时的自转速度之积为常数,称地球自转行程常数。本文还计算了未来两个时间点的日长,预测209.6 Ma后地球日长可达25小时。 展开更多
关键词 自转速度 地球年龄 历时年龄 地球日长 反比例双曲线 三段状态 行程常数
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Oxidation of a Zr_(46)Cu_(46)Al_(7)Gd_(1)bulk metallic glass detected via optical characterizations
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作者 Weijie Xie Mingxing Li +4 位作者 Jiashu Cao Liwei Hu Chao Wang Wei-Hua Wang Yanhui Liu 《Science China Materials》 SCIE EI CAS CSCD 2021年第4期973-978,共6页
Oxidation of metallic glasses has been shown to be different from crystalline alloys due to the disordered atomic structures and far-from-equilibrium state,and quick characterization is required to reveal their early ... Oxidation of metallic glasses has been shown to be different from crystalline alloys due to the disordered atomic structures and far-from-equilibrium state,and quick characterization is required to reveal their early stage oxidation.In this study,we investigated the oxidation behavior of a Zr_(46)Cu_(46)Al_(7)Gd_(1)bulk metallic glass by measuring the changes of optical constants via spectroscopic ellipsometry.Characterizations with X-ray diffraction,scanning electron microscopy,and thermogravimetric analyzer confirmed that the changes of pseudo-optical constants reflected not only the onset temperature at which the alloys underwent obvious oxidation,but also the subtle oxidation which was tedious to characterize.Our study suggests a more efficient and accurate approach to understand the oxidation of metallic glasses with temperature,time and compositions. 展开更多
关键词 metallic glasses spectroscopic ellipsometry OXIDATION
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