共查询到20条相似文献，搜索用时 406 毫秒
1.
根据太阳系行星物质的主要性态和大小,人们通常将其分成行星（包括类地行星和类木行星）、卫星、小行星、彗星和流星体。类地行星包括水星、金星、地球和火星;类木行星包括木星、土星、天王星和海王星;质量较大的小行星和卫星的内部结构与类地行星相似,质量较小的小行星和卫星以及流星体主要由岩石和金属组成;彗星是含有太阳系形成时期物质且没有经过太多物理和化学演化的冰态小天体。 相似文献
2.
天文学的起源和萌芽可追溯到人类文明的起源,而神话是与人类文明同时诞生的。古今中外的神或神化了的古代英雄,是古代人民对自然现象和社会生活的一种天真解释和美丽的向往。星座神话正是把科学和文化、天文与人文融合在一起的交融点。 相似文献
3.
赵君亮 《中国科学院上海天文台年刊》2002,(1)
简要地总结了 2 0 0 1年度上海天文台科研工作 ,包括知识创新工程和基础研究、实测和技术工作、人才培养和人才引进、科研支撑和相关管理工作 ,以及国际合作与学术交流等方面取得的成绩和若干存在问题 相似文献
4.
控制系统能衔接、集成和管理射电望远镜的软硬件系统。控制系统的序列化工具可以将射电望远镜的不同设备、操作系统、编程语言和网络之间传输的信息进行编码和解码,增强系统之间数据的传输效率。分析和比较了3款二进制序列化工具Msgpack,Protobuf和Flatbuffers的编码原理及特性,并通过一个实例测试了它们的序列化数据大小、序列化时间和中央处理器利用率。结果表明,Msgpack的综合性能优于Protobuf和Flatbuffers,适用于周期长、需求易变的射电望远镜系统之间传输信息的编码和解码。 相似文献
5.
诞生于1925年的德意志博物馆蔡司天文馆是世界上第一座天文馆。多年以来,德意志博物馆以其多功能的场馆和丰富的展品,致力于天文学等科学领域的教育和研究,成为世界上最大和最好的科技博物馆之一。这里我们重点介绍其天文馆和天文展览等相关内容。 相似文献
6.
专著<太阳活动区物理>最近由南京大学出版社出版和发行.该专著由作者,南京大学方成院士、丁明德教授和陈鹏飞教授,以多年来的太阳物理学研究和指导研究生的科研为基础,并结合国内外太阳物理学最新研究成果编写而成的,主要阐述了研究太阳活动区和各种太阳活动现象的观测事实、基本理论、基本方法和主要研究成果. 相似文献
7.
赵君亮 《中国科学院上海天文台年刊》2003,(1)
对 2 0 0 2年度上海天文台科研工作作了简要总结 ,其内容包括知识创新工程和基础研究、实测和技术工作、人才培养和人才引进、科研支撑和相关管理工作、国际合作与学术交流等方面取得的成绩和主要存在问题 相似文献
8.
小行星与慧星研究
小行星和彗星是45亿年前太阳系形成时遗留的原始残骸,包含着太阳系早期的物理和化学信息,对研究太阳系起源和行星系统形成具有重要科学意义,同时精密确定其轨道动力学演化又是目前空间环境和地球安全方面的重要现实需求。 相似文献
9.
坐落在密西西比河畔的巴吞鲁日,是美国南部路易斯安那州的首府。这座混合了印地安、西班牙、法国、英国和非洲等文化元素的城市,拥有丰富和传奇的历史。路易斯安那州艺术和科学博物馆无疑是巴吞鲁日的骄傲。利用古老的火车站改建而成的路易斯安那州艺术和科学博物馆（缩写LASM）,为各年龄段的游客提供教育和娱乐服务。LASM的艺术画廊提供不断更新的美术展览和永久的收藏展示。 相似文献
10.
约翰·舍纳的天球仪
在文艺复兴时代,由于航海和地理大发现的需要,天球仪和地球仪同时获得蓬勃发展。那时天球仪和地球仪往往是成双成对制造的,球仪（即天球仪和地球仪）的制造技术有了长足的进步。 相似文献
11.
12.
Seungheon Song C. W. Jung S. Y. Kim Youngbo Choi 《Astrophysics and Space Science》1992,193(2):217-234
TheN-body problem does not have an exact and analytic solution, and computer technique or computer simulation can be a good candidate to solve it. Computing speed in computer simulation is very important. There are many algorithms and computational methods in computer simulation which reduce computer time.In this report a computer simulation model in a cylindrical coordinate, in which the FACR (Fourier Analysis and Cyclic Reduction) method is used, has been proposed and demonstrated the presence of spiral, barred, and ringed galaxy. The method using a cylindrical grid has good symmetrical properties specially for rotating stellar systems. 相似文献
13.
原子钟噪声的蒙特卡络模拟方法 总被引：1，自引：0，他引：1
讨论了原子钟噪声的蒙特卡络模拟方法．具体过程是：先产生模拟所需的正态分布随机数，从实际钟的阿仑方差估算出噪声电平，然后用１组递点函数产生高质量的模拟钟时差的随机序列．在对１台商品铯钟进行具体模拟后，给出了真实数据与模拟值的阿仑方差之问的相符程度，最后对实际问题进行了分析． 相似文献
14.
We present results of a numerical simulation of a stellar jet from a source with supersonic variations in the outflow velocity. The simulation is compared with both analytical predictions and observations. 相似文献
15.
A plasma simulation code is applied to interpret the instabilities in an expanding planetary nebula. The temperature of the
central star of a planetary nebula is assumed as above 50,000 K. Most of the atoms are ionized at this temperature. Since
ionization cannot be neglected for such a hot plasma, the electrostatic instability should be taken into account. In the one
dimensional electrostatic simulation, Maxwell and Vlasov equations are used and the fast Fourier transform is applied. The
calculated drift velocity in the simulation is found comparable with the expansion velocity of a planetary nebula. The linear
and non-linear behaviors of the simulated nebular plasma have been investigated in phase space; the simulation results agree
with the theory.
This revised version was published online in September 2006 with corrections to the Cover Date. 相似文献
16.
S. Wiehle F. Plaschke K.-H. Glassmeier H.U. Auster J. Mueller E. Georgescu D.G. Sibeck 《Planetary and Space Science》2011,59(8):661-671
The spacecraft P1 of the new ARTEMIS (Acceleration, Reconnection, Turbulence, and Electrodynamics of the Moon's Interaction with the Sun) mission passed the lunar wake for the first time on February 13, 2010. We present magnetic field and plasma data of this event and results of 3D hybrid simulations. As the solar wind magnetic field was highly dynamic during the passage, a simulation with stationary solar wind input cannot distinguish whether distortions were caused by these solar wind variations or by the lunar wake; therefore, a dynamic real-time simulation of the flyby has been performed. The input values of this simulation are taken from NASA OMNI data and adapted to the P1 data, resulting in a good agreement between simulation and measurements. Combined with the stationary simulation showing non-transient lunar wake structures, a separation of solar wind and wake effects is achieved. An anisotropy in the magnitude of the plasma bulk flow velocity caused by a non-vanishing magnetic field component parallel to the solar wind flow and perturbations created by counterstreaming ions in the lunar wake are observed in data and simulations. The simulations help to interpret the data granting us the opportunity to examine the entire lunar plasma environment and, thus, extending the possibilities of measurements alone: A comparison of a simulation cross section to theoretical predictions of MHD wave propagation shows that all three basic MHD modes are present in the lunar wake and that their expansion governs the lunar wake refilling process. 相似文献
17.
We have made a Monte Carlo simulation of the intergalactic absorption in order to model the Lyman continuum absorption, which is required to estimate the escape fraction of the Lyman continuum from distant galaxies. To input into the simulation, we derive an empirical distribution function of the intergalactic absorbers which reproduces recent observational statistics of the Lyman α forest, Lyman limit systems (LLSs) and damped Lyman α systems (DLAs) simultaneously. In particular, we assume a common functional form of the number evolution along the redshift for all types of absorbers. The Lyman series transmissions in our simulation reproduce the observed redshift evolution of the transmissions excellently, and the Lyman continuum transmission also agrees with an observed estimation which is still quite rare in the literature. The probability distribution of the Lyman α opacity in our simulation is lognormal with a tail towards a large opacity. This tail is produced by DLAs. The probability distribution of the Lyman continuum opacity in our simulation also shows a broad tail towards a large opacity. This tail is produced by LLSs. Because of the rarity of LLSs, we have a chance to have a clean line of sight in the Lyman continuum even for z ∼ 4 with a probability of about 20 per cent. Our simulation expects a good correlation between the Lyman continuum opacity and the Lyman α opacity, which may be useful to estimate the former from the latter for an individual line of sight. 相似文献
18.
A numerical simulation of the disk dynamics of a flat stellar-gaseous galaxy is presented. This simulation is based on N-body modelling for a stellar disk, together with integration of the two-dimensional hydrodynamic equations for a gaseous disk. The existence of a quasi-periodic regime of disk evolution found earlier in a purely hydrodynamic simulation is confirmed. Intense gas flows in the central area of the disk due to the saddle point of the bar potential can support the active galactic nuclei in Seyfert galaxies and form double nuclei. 相似文献
19.
针对嫦娥二号探测器在轨运行阶段的仿真需求,充分发挥视景仿真的优势,利用嫦娥一号探测器获得的地形和影像数据、日地月嫦娥二号探测器星历数据,基于OSG(OpenScene Graph)设计了针对嫦娥二号任务的在轨运行视景仿真系统。论述了该系统的开发平台,系统总体框架,并对系统的实现进行了详细描述。论述了月球模型数据构建,嫦娥二号探测器构建,星历数据库构建与访问,仿真实体空间位置的实时更新,CCD立体相机探测过程的仿真,视点的控制等实现方法。仿真结果表明系统完全能满足嫦娥二号任务在轨运行仿真的要求,并已应用于嫦娥二号任务执行过程中。 相似文献
20.
In the equatorial plasmasphere, plasma waves are frequently observed. To improve our understanding of the mechanism generating plasma waves from instabilities, a comparison of observations, linear growth-rate calculations, and simulation results is presented. To start the numerical experiments from realistic initial plasma conditions, we use the initial parameters inferred from observational data obtained around the plasma-wave generation region by the Akebono satellite. The linear growth rates of waves of different modes are calculated under resonance conditions, and compared with simulation results and observations. By employing numerical experiments by a particle code, we first show that upper hybrid-, Z-, and whistler-mode waves are excited through instabilities driven by a ring-type velocity distribution. The simulation results suggest a possibility that energetic electrons with energies of some tens of keV confined around the geomagnetic equator are responsible for the observed enhancements of Z- and whistler-mode waves. While the comparison between linear growth-rate calculations and observations shows the different tendency of wave amplitude of Z-mode and whistler-mode waves, the wave amplitude of these wave modes in the simulation results is consistent with the observation. 相似文献