Correlation between the Mayan calendar and ours: Astronomy helps to answer why the most popular correlation (GMT) is wrong     

J. Kloko ník  J. Kostelecký  V. Bhm  B. Bhm  J. Vondrk  F. Vítek 《Astronomische Nachrichten》2008,329(4):426-436

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A solar super‐flare as cause for the 14C variation in AD 774/5?     

R. Neuhuser  V. V. Hambaryan 《Astronomische Nachrichten》2014,335(9):949-963

We present further considerations regarding the strong ¹⁴C variation in AD 774/5. For its cause, either a solar super‐flare or a short gamma‐ray burst were suggested. We show that all kinds of stellar or neutron star flares would be too weak for the observed energy input at Earth in AD 774/5. Even though Maehara et al. (2012) present two super‐flares with ∼10³⁵ erg of presumably solar‐type stars, we would like to caution: These two stars are poorly studied and may well be close binaries, and/or having a M‐type dwarf companion, and/or may be much younger and/or much more magnetic than the Sun – in any such case, they might not be true solar analog stars. From the frequency of large stellar flares averaged over all stellar activity phases (maybe obtained only during grand activity maxima), one can derive (a limit of) the probability for a large solar flare at a random time of normal activity: We find the probability for one flare within 3000 years to be possibly as low as 0.3 to 0.008 considering the full 1σ error range. Given the energy estimate in Miyake et al. (2012) for the AD 774/5 event, it would need to be ∼2000 stronger than the Carrington event as solar super‐flare. If the AD 774/5 event as solar flare would be beamed (to an angle of only ∼24°), 100 times lower energy would be needed. A new AD 774/5 energy estimate by Usoskin et al. (2013) with a different carbon cycle model, yielding 4 ot 6 time lower ¹⁴C production, predicts 4–6 times less energy. If both reductions are applied, the AD 774/5 event would need to be only ∼4 times stronger than the Carrington event in 1859 (if both had similar spectra). However, neither ¹⁴C nor ¹⁰Be peaks were found around AD 1859. Hence, the AD 774/5 event (as solar flare) either was not beamed that strongly, and/or it would have been much more than 4‐6 times stronger than Carrington, and/or the lower energy estimate (Usoskin et al. 2013) is not correct, and/or such solar flares cannot form (enough) ¹⁴C and ¹⁰Be. The 1956 solar energetic particle event was followed by a small decrease in directly observed cosmic rays. We conclude that large solar super‐flares remain very unlikely as the cause for the ¹⁴C increase in AD 774/5. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

黄河流域高质量发展空间格局演进——基于新发展理念视角北大核心CSCD     

郝金连  王利  孙根年  孙凡凯  王东华 《中国沙漠》2022,42(6):266-276

以黄河流域66个市级单元为研究对象,基于新发展理念选取34项指标构建高质量发展指标体系,利用熵值法计算得到黄河流域高质量发展水平,以高质量发展水平、高质量发展平均增量和平均增速为变量,利用ESDA法分析2000—2020年黄河流域高质量发展空间关联和格局演化特征。结果表明:(1)2000—2020年黄河流域高质量发展水平相似市域空间相关,高质量发展水平在波动中有所提高,发展趋于均衡。(2)2000—2015年,黄河流域高质量发展平均增量和平均增速的空间关联较为显著,均呈现出强集聚—弱集聚—较强集聚演变特征,增长状态相似市域彼此邻近;但2015—2020年增长状态相似市域随机分布,空间不相关。(3)高质量发展平均增量和平均增速格局变化较大,高值区均由东部向中部再向西部转移,高值区数量大于低值区数量,黄河流域高质量整体发展较快。平均增量冷热点区呈现相对分散—集中分布—分散布局的态势,平均增速相似市域由相对分散向集中连片演化,不同等级冷热点圈层分布。(4)发展基础相对较差的区域增长速度较快,城市群仍是带动黄河流域高质量发展的重点区域。未来应坚持新发展理念,创新城市群合作模式,推动黄河流域高质量一体化发展。  相似文献   

Supernova SN 1006 in two historic Yemeni reports     

W. Rada  R. Neuhuser 《Astronomische Nachrichten》2015,336(3):249-257

We present two Arabic texts of historic observations of supernova SN 1006 from Yemen as reported by al‐Yamānī and Ibn al‐Dayba^c (14th to 16th century AD). An English translation of the report by the latter was given before (Stephenson & Green 2002), but the original Arabic text was not yet published. In addition, we present for the first time the earlier report, also from Yemen, namely by al‐Yamānī in its original Arabic and with our English translation. It is quite obvious that the report by Ibn al‐Dayba^c is based on the report by al‐Yamānī(or a common source), but the earlier report by al‐Yamānī is more detailed and in better (Arabic) language. We discuss in detail the dating of these observations. The most striking difference to other reports about SN 1006 is the apparent early discovery in Yemen in the evening of 15th of Rajab of the year 396h (i.e. AD 1006 April 17±2 on the Julian calendar), as reported by both al‐Yamānī and Ibn al‐Dayba^c, i.e. ∼1.5 weeks earlier than the otherwise earliest known reports. We also briefly discuss other information from the Yemeni reports on brightness, light curve, duration of visibility, location, stationarity, and color. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

延伸期天气过程预报在线展示系统的设计与实现     

马浩  樊高峰  李正泉  毛裕定  雷媛 《干旱气象》2015,(1):167-173

近年来极端天气气候事件频发,对人民生产生活造成了严重影响,延伸期天气预报得到了空前的重视。随着低频天气图方法在全国的推广和普及,延伸期天气过程预报在我国各地得到了蓬勃开展。为了与过程预报的服务需求相适应,浙江省气候中心设计研发了延伸期天气过程预报在线展示系统。本文从设计思想、系统架构、未来设想3个方面对在线展示系统进行了详细介绍。该系统立足于以预报对象为导向的原则,设置了强降水过程和强降温过程2个栏目。强降水过程栏目涵盖预报与实况对比图形、预报文稿、动态评分表格、实况简述表格、实况详述表格5部分内容,强降温过程栏目展示内容与强降水过程栏目类似,但不包含动态评分表格。未来拟从强降温过程指标判别的合理性、强降温过程评分方案、拓展预报体系3个方面对系统功能进行改进和优化。  相似文献   

Thinking like a geologist: The culture of geology Mawson lecture 1996∗     

G. Seddon 《Australian Journal of Earth Sciences》2013,60(5):487-495

Geology plays a crucial role in both the scientific and the popular culture; it has transformed the way ordinary people look at the world over the last two centuries. Much of this transformation is understood in terms of information about the age of the earth, the disposition of the continents, and the evolution of living things. The two main concerns of this paper are with geology as education, and geology as a system of thought, a way of thinking about the world. My central question is how does a grounding in geology affect the cast of mind, the way one thinks, perceives and behaves? What is the culture of geology? Conclusions are of two kinds. Some of the propositions advanced about the nature of geology in relation to the other sciences and our general culture are: (i) there is no hierarchy of the sciences; (ii) geology is a Romantic science rather than a Classical one; (iii) there is no such thing as the scientific method; (iv) geologists often attempt to reconcile competing hypotheses; (v) geological phenomena are often of an almost irreducible complexity and their investigation is beset by problems of scale, both spatial and temporal; and (vi) the concept of ‘universality’ has a distinctive application in geology. Among the non‐professional uses of geology are: (i) human history is incomplete without environmental history; (ii) geology has application in environmental planning and management, but this requires judgement and experience as knowledge of the geology is not enough, it is equally important to know when it can safely be overridden, when it is useful background, and when it is critically important to decision‐making; and (iii) an awareness of the geology of a region enhances the sense of place—our sense of our individual and communal identities owes much to an awareness of place.  相似文献   

《授时历》五星推步的精度研究     

李勇 《天文学报》2011,52(1)

着重考察了《授时历》的步五星术,考校、复原了其推步方法.(1)推步了1299年木星历,并与已有研究进行比对,从而确认恢复方法的正确性.(2)得出《授时历》在1280～1650年间推步五星黄经的精度,木星、火星、土星、金星和水星的误差的绝对值平均分别为0.49°、1.91°、0.70°、2.82°和5.01°,木星、土星的精度较高.(3)指出将现代天文方法获取的《授时历》五星参数(周率、历率、度率、合应及历应)精确值代入《授时历》推步模型,木星、土星的推步精度并未提高,误差分别为1.83°和1.21°,而水星、金星和火星的误差却大幅加大,结果分别为30.04°、54.86°和10.82°.说明某些重要参数的修正并不能改善推步结果.  相似文献   

The sunspot observations by Samuel Heinrich Schwabe     

R. Arlt 《Astronomische Nachrichten》2011,332(8):805-814

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The significance of the Hansen Ideal space frame     

E.F.M. Jochim 《Astronomische Nachrichten》2012,333(8):774-783

Known and unknown properties of Hansen Ideal coordinates are summarized. It is shown that the ideal space frame is a general and necessary component of basic celestial mechanics and astrodynamics, as well as of any theory of motion. A typical consequence is the intimate correlation of the Hansen frame with the Lagrange constraint within the method of the variation of the parameters. The use of observations in the ideal frame may allow conclusions on the intergalactic fundamental coordinate system (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

GEOGRAPHY IN THREE WORLDS: HOW POPPER'S SYSTEM CAN HELP ELUCIDATE DICHOTOMIES AND CHANGES IN THE DISCIPLINE*     

James H. Bird 《The Professional geographer》1985,37(4):403-409

Popper's concept of Worlds 1. 2, and 3 is discussed briefly in the light of idealism and materialism and to illustrate the debate about reification and reductionism. Then six types of change in geography are classified as changes in the phenomenal environment (World 1) and in that part of the behavioral environment that constitutes World 3. These changes involve those comparisons within or between “Worlds” that identify future research problems.  相似文献