共查询到20条相似文献,搜索用时 15 毫秒
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高能天体物理观测中,宇宙线带电粒子通过探测器丢失的能量常是产生探测器本底信号的重要来源。宇宙线产生的信号与它通过探测器的径迹长度和探测器大小、形状有关。因气球X射线天文观测和γ射线暴观测的需要,空间天文实验室研制了若干种正比计数器,为此我们进行了宇宙线通过正比管径迹长度的模拟计算,它是整个设计工作中的一部分。 相似文献
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Recent observations have provided much real information about the acceleration of particles in solar flares. High-reliability data about accelerated particles have been obtained for an impulsive phase of some flares of the activity cycle XXII. Therefore, it seems reasonable to re-estimate the amount of Li atoms produced in the upper photospheric layers by – reactions. A value of 5 × 10 29 nuclei during the largest impulsive solar events has been found from calculations for the thick-target model. This agrees with observations of the line of lithium. In conclusion, the probability of enhanced Li absorption observed after large impulsive flares in the sunspot penumbra is discussed. 相似文献
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The FeOOH phase in Apollo 16 rocks is akaganéite. Other polymorphs of FeOOH, i.e. geothite and lepidocrocite, may exist but have not been identified by X-ray diffraction. Experiments performed during this study using akaganéite, geothite, and lepidocrocite placed at 135°C and under a pumping vacuum of 10?2 torr, demonstrate that these forms of FeOOH are not stable on the surface of the Moon, where daytime temperatures are about 140°C and pressures are about 10?7 torr. The effect of the vacuum is to strip off the water, and the temperature speeds up this dehydration process. These data lend support to the contention of Taylor et al. (1973) that the FeOOH in lunar rocks formed by the oxyhydration of lawrencite, FeCl2, due to contamination by terrestrial water vapor. 相似文献
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为了适应星际探测的需求,本文建立了在新的精度要求下土星卫星运动对应的力学模型,具体讨论了土卫八的运动,并针对主要摄动源土卫六的引力作用,建立了轨道变化的分析解,以此表明建立了土卫运动理论该采取的途径和精密定轨宜采用以轨道根数作为状态量的数值定轨方法。 相似文献
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A statistical large-scale study of filaments has revealed the existence of a functional dependence of the length of filaments (the angular distance between the ends of a filament, measured on a great circle on a sphere) on their inclination to lines of solar latitude. A cluster analysis method has been applied to the study of filament evolution and an evolutionary classification of filaments is proposed. The results depend on the differential velocity of filaments. Different types of evolution sequences were obtained, and the evolution of some particular filaments was specially analyzed. 相似文献
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High-quality stratospheric photographs in the continuum were used to investigate spatial scales of the solar granulation field. Two-dimensional intensity power spectra are shown to contain most frequently the modes corresponding to the sizes of granules, protogranules, mesogranules, and supergranules. The place of these four, the most steady formations of the quiet Sun in the global structure of the solar photosphere, is discussed as well as their interconnection and their relation to weak and strong magnetic fields. The protogranulation scale is argued to play an important role in organization of the fine structure of the photosphere and magnetic fields in the quiet and active regions of the Sun. 相似文献
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引力常数变化对地球自转长期变化的影响 总被引:1,自引:0,他引:1
李林森 《中国科学院上海天文台年刊》2002,(1)
探讨和估计了各种引力常数变化理论对地球角速度和日长变化的影响。各种引力常数变化理论包括了引力常数G随时间、空间以及速度变化等几个方面的影响。另外也估计了对地球自转角速度和日长变化产生的效应。其中有些研究对探讨地球自转变化也有启发意义。 相似文献
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本文研究了表面边界位置对太阳ρ模绝热本征振荡频率的影响。数值计算结果表明,对于v4000μHz的中低阶p模,表面边界置于温度极小点所引起的本征振荡频率的计算误差随着v和l的增大,表面边界点位置对太阳理论振荡频率的影响增大,色球结构对太阳p模振荡频率的影响已变得不可忽略。 相似文献
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本文采用了合理的力学模型和可靠的计算方法,研究了近地小行星轨道运动,揭示了共振(轨道共振和长期共振)在其轨道演化中的作用,并初步探讨了近地小行星的起源问题。 相似文献
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本文简要地介绍了目前太阳系外行星系统动力演化的研究现状。我们用数值模拟方法和并从分析的角度研究了GJ 876和HD 82 943。通过分析不同的共面和非共面构型 ,我们发现所有的稳定轨道都和2 :1共振有关 ,此外我们还发现在这两个系统内存在近星点共振—对应了两个行星的近星点经度之差在1 80 0或者 0 0附近秤动。这两种机制对维持行星系统的稳定性起了重要作用。 相似文献
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本文主要从理论上用解析方法讨论日珥视向速度随深度变化对谱线轮廓对称性的影响,得到的结论具有普遍性。第二节的分析表明,日珥的谱线轮廓可表示为二项叠加,其中第一项与源函数无关,只依赖于速度场模型,源函数分布仅通过第二项对谱线轮廓产生影响。然后在源函数不随深度变化的假定下,讨论各种速度场模型的谱线轮廓是否对称。得到的结论为:(1)常源函数与常速度场结合的谱线轮廓为对称轮廓;(2)常源函数与线性对称速度场结合的谱线也是对称轮廓;(3)常源函数与线性非对称速度场结合的谱线轮廓为不对称轮廓。最后,用数值计算对理论分析结果进行了检验。 相似文献
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Jacques Jedwab 《Meteoritics & planetary science》1975,10(3):233-240
A method is described for extracting magnetic micron-size particles from manganese nodules, and for studying the selected particles by light microscopy, scanning electron microscopy, electron microprobe and X-ray diffraction. 相似文献
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本文根据在考虑磁光效应的条件下由斯托克斯参数转移方程组的数值解求得的斯托克斯参数轮廓,探讨V轮廓的不对称性和剩余圆偏振产生的原因,并论证白光磁象仪的工作原理。本文指出,V轮廓的不对称量与磁场强度和速度场精度都有关,因此文[1]和[4]的两个极端性论断都与实际情况不符。 相似文献
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关于勒让德多项式的算法问题 总被引:2,自引:0,他引:2
本文讨论勒让德多项式P_1(x)和缔合勒让德多项式P_(1m)(x)的两种算法,即直接计算和递推算法,并给出相应的计算公式,当1取值较大时,也可以保证达到较高的精度。 相似文献
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本文讨论了知识创新与专业图书馆的关系,论述了专业图书馆在科研工作中的地位与作用,并强调了在知识创新环境下,加强图书情报工作的重要性。 相似文献
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Elsebeth Thomsen 《Meteoritics & planetary science》1980,15(1):87-91
At various times the Black Stone of the Ka'ba has been considered to be lava, basalt, a meteorite and lately an agate. This paper discusses the possibility that it may consist of impactite glass, derived from the meteoritic craters of Al-Hadidah, called Wabar. 相似文献
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《紫金山天文台台刊》1998,(2)
On the basis of photogravitational theory, the influence of solar photogravitation on the motion of comet tail is discussed in this paper. It is shown that for plasma tail and some of the dust tail, there are two coplaner libration points L6, L7, and three collinear points L21, L22,L3 at most. The regions in which the dust grain of comet tail can move are also obtained. 相似文献