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我们都希望生活在一个更安全、更安定的世界里。然而,地震、飓风、洪水、交通事故、传染病和工业事故,除了给人类带来物质损失以外,每年还导致成千上万的人员伤亡。为了应对这些威胁,国际标准提供了广为认可的解决方案。国际标准在防止和减少人员伤亡以及物质损失方面所起到的重要作用日益突出,标准在这方面的应用也更加广泛。今年世界标准日的主题是"标准使世界更安全"。由国际电工委员会(IEC)、国际标准化组织(ISO)和国际电信联盟(ITU)这三大国际标准化组织所制定的国际标准构成了一个非常有价值的安全网络。IEC、ISO和ITU所涵盖… 相似文献
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Taketoshi Hibiya Keisuke Nagafuchi Suguru Shiratori Noriyoshi Yamane Shumpei Ozawa 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2008,41(12):2107-2111
In order to experimentally investigate the Marangoni flow of low-Prandtl-number fluids in a liquid bridge geometry under the condition of small Marangoni numbers close to the critical Marangoni numbers Mac1 and Mac2, the formation of a liquid bridge of silver was attempted. The available temperature difference between the upper and lower rods to obtain a small Marangoni number, such as Ma = 50, was calculated for a 5 mm high liquid bridge for several molten metals. For molten silver, the possible temperature difference was estimated to be 16 K, whereas, for molten silicon, this was 0.38 K, which is unrealistic for the purposes of experiments. For silver, a free surface can be obtained in the wide range of oxygen partial pressures, whereas, for molten silicon, the available oxygen partial pressure range is very small; equilibrium oxygen partial pressure for SiO2 formation is as low as 1.1 × 10−14 Pa. A liquid bridge of molten silver was successfully prepared and temperature oscillation was observed; the estimated Marangoni number was 160 and oscillation frequency was 0.26 Hz. 相似文献
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