20 resultados para 171-1051B

em Chinese Academy of Sciences Institutional Repositories Grid Portal


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在中国原子能科学研究院的HI 13串列加速器上通过157Gd(19F,5n)171Ta重离子熔合蒸发反应布居了171Ta的高自旋态,以多普勒移动衰减法的峰形分析法分析了171Tah9/2质子1/2[541]转动带的6条能级的寿命,得到了这6条能级的平均寿命值.

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力学作为“自然哲学的数学原理”,乃是支撑物理科学和工程技术的一个重要支柱。它以产生宏观运动的相互作用为对象,以特有的手法衡量不同因素的相对重要性,从复杂的现象中,定量提炼出主要控制机理,为认识自然提供模型和工具,为工程提供设计基础和先导。

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20年代,胡刚复先生为我国度量衡统一确定一个市制,对米、千克、升的公制有一个3、2、1的简单比例关系。这一制度沿用至今,不仅已被科技界视为当然,且更广泛便利人民生活,定将一直延续下去。反观当时我国各地方、各行业,如营造尺、16两、大斗小称等度量衡各异的混乱;以及今日美、英等国被英尺、磅、加仑的英制零星折算产生的经常困扰;特别是对工程及商务所带来的经济损失,以致积重难返的窘态。可以悟出胡先生这一简明建议的重大功绩,堪与两千年前同文同轨、权衡悉依秦制的炎黄文明相映生辉。在纪念胡先生百周年时,谨撰此文,寓意于简单3、2、1系数的巧合,借以颂扬胡先生的功绩。

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本文采用近似的激波关系、球锥体压力分布、平衡气体状态方程、边界层厚度计算公式及转捩准则等,按照流管法计算了4种再入飞行器的外流转捩雷诺数和转捩距离,并给出了高硅氧、碳石英、碳碳球锥模型的转捩雷诺数范围,对再入飞行器和模型的计算结果作了分析和比较。

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在文献[1]的基础上,本文较深入地讨论了二次谐振法,推导出实用计算公式。简化后,可分别得出变电容法和变频率法,扩大了文献[1]的适用范围和灵活性。对几种脉冲电容器,给出了分布电感变化曲线及短路使用时的Lxo和fo,讨论了谐振法的误差和精度。结束语中还对几种测量分布电感的方法作了比较。

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本文介绍一个值得注意的高灵敏度全息干涉方法.文献[2]指出,在全息干涉两次曝光间对参考光移相,可以提高灵敏度,并报道了移相π/2时的实验结果.本文详细分析了移相技术,指出此法在移相π/2时的分辨率可高达1/1000波长左右,比普通两次曝光全息技术(其移相值为0)的灵敏度高25.4倍;并指出,移相值大于π/2小于π时灵敏度可以进一步提高,最佳移相值应在π附近.本文附有一个低密度变化流场的实验结果,说明本方法显示低密度变化流场的能力.讨论了应用中的一些问题.

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The influence of the momentum addition, which may be associated with the average or fluctuation transverse component of the magnetic field or others, on the acceleration the solar wind or stellar wind is studied in a local streamtube. The results show that the larger the momentum addition the stronger the acceleration of the wind. For example, if the typical transverse magnetic field is about 0.1 of the longitudinal field, the velocity of the solar wind at 1 AU may be increased by 40%. The coronal hole may be considered as a streamtube, the presence of a high stream from the coronal hole may be explained by the existence of an average or fluctuation transverse magnetic field in the streamtube. A similar conclusion may be applied to the polar region, where the velocity of the solar wind will be larger than elsewhere as if there is a transverse component of magnetic field, as well as to the stellar wind. The influence of other parameters on the acceleration of the solar wind is also discussed. From the viewpoint of the solar wind mechanism, the present paper shows that the momentum addition in the subsonic flow region can increase the velocity of the solar wind at 1 AU.

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In this paper an analysis of the kinetic theory of the continuous-wave flow chemical lasers(CWFCL) is presented with emphasis being laid on the effects of inhomogeneous broadeningon CWFCL's performance. The results obtained are applicable to the case where laser fre-quency is either coincident or incoincident with that of the eenter of the line shape. This rela-tion has been,compared with that of the rate model in common use. These two models are almostidentical as the broadening parameter η is larger than 1. The smaller the value of η, thegreater the difference between the results of these two models will be. For fixed η, the dif-ferences between fhe results of the two models increase with the increase of the frequencyshift parameter ξ. When η is about less than 0.2. the kinetic model can predict exactly the in-homogeneous broadening effects,while the rate model cannot.

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数值模拟了二维平面激波从抛物面上反射在可燃气体中聚焦的过程,研究了形成爆轰波的点火特性,对理想化学当量比氢气/空气混合气体,在初始压强20kPa的条件下,马赫数2.6-2.8的激波聚焦能产生两个点火区:第1个点火区是反射激波会聚引起的,第2个点火区是由入射激波在抛物面上发生马赫反射引起的.这种条件下流场中会出现爆燃转爆轰,起爆点分别分布在管道壁面、抛物反射面和第2点火区附近.起爆机理分别为激波管道壁面反射、点火诱导激波的抛物面反射和点火诱导的激波与第2点火区产生的爆燃波的相互作用,不同的点火和起爆过程导致了不同的流场波系结构,同时影响了爆轰波传播的波动力学过程.

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特征分析表明:对原始扰动量的抛物化稳定性方程组(PSE),它在亚、超音速区分别具有椭圆和抛物特性,给出PSE特征对马赫数的依赖关系,阐明PSE仅把信息对流-扩散传播特性抛物化,而保留了信息对流-扰动传播特性,因此PSE应称为扩散抛物化稳定性方程(DPSE)。

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用过滤电弧技术在高速钢表面沉积了TiN/TiCrN/CrN/CrTiN多层膜 ,用扫描电镜 (SEM )观察了截面和断口形貌及划痕后的形貌。使用俄歇电子谱仪进行剥层成分分析 ,用纳米压痕仪测试了多层膜和单层膜的显微硬度和弹性模量。结果表明 ,在调制周期大于 10 0nm时 ,多层膜的显微硬度符合Hall Petch关系 ,在 80nm时 ,则脱离线性关系。划痕法测试多层膜的结合力达到 80N。

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首先讨论了著名力学家K.Krausz和A.S.Krausz关于Paris公式物理本质研究的成果,从材料的微观结构和裂纹尖端的应力场出发,应用位错动力学理论,热激活能理论和速率过程理论对疲劳裂纹扩展规律进行了微观到宏观的探讨。最终推导出疲劳裂纹扩展速率的一个解析表示式,该式严格地定了Paris公式的两个试验常数,赋予了Paris公式明确的物理意义,从而真实地揭示了Paris公式的物理本质,为这一经验的普遍规律奠定了理论基础。