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581.
582.
根据1994年6月—1995年12月期间在新疆天山南坡的奎先达坂进行的云量观测结果和邻近的巴仑台气象站的多年气候观测资料作统计分析,作者推断奎先达坂的天文可用小时数和天文夜数均可与目前世界上最优良的天文台址相比。 相似文献
583.
Previous work relating flares to evolutionary changes of photospheric solar magnetic fields are reviewed and reinterpreted in the light of recent observations of cancelling magnetic fields. In line-of-sight magnetograms and H-alpha filtergrams from Big Bear Solar Observatory, we confirm the following 3 associations: (a) the occurrence of many flares in the vicinity of emerging magnetic flux regions (Rust, 1974), but only at locations where cancellation has been observed or inferred; (b) the occurrence of flares at sites where the magnetic flux is increasing on one side of a polarity inversion line and concurrently decreasing on the other (Martres et al., 1968; Ribes, 1969); and (c) the occurrence of flares at sites where cancellation is the only observed change in the magnetograms for at least several hours before a flare (Martin, Livi, and Wang, 1985). Because cancellation (or the localized decrease in the line-of-sight component of magnetic flux) is the only common factor in all of these circumstances, suggest that cancellation is the more general association that includes the other associations as special cases. We propose the hypothesis that cancellation is a necessary, evolutionary precondition for flares. We also confirm the observation of Martin, Livi, and Wang (1985) that the initial parts of flares occur in close proximity to cancellation sites but that during later phases, the flare emission can spread to other parts of the magnetic field that are weak, strong, or not cancelling. 相似文献
584.
重大突发事件的应对处置能力是国家治理体系和治理能力的重要组成部分,也是国家治理能力现代化的重要体现。志愿服务作为新时代社会治理的重要元素,在重大突发事件应对中发挥着独特的作用。然而从近年来重大突发事件应对的现状来看,无论是在质还是量上,志愿服务都难以满足应急工作的需要。通过对近年来重大突发事件的梳理和对灾区的实证调研,提出了重大突发事件中增强志愿服务应急法治能力建设,加强“平战结合”的专业建设能力,提升“互联网+”多方合作的联动协调能力,制定志愿服务应急的精准激励保障能力等方面的思考和建议,对于改善重大突发事件中志愿服务应急能力困境具有一定的价值。 相似文献
585.
思维科学与地理思维研究 总被引:12,自引:0,他引:12
思维科学是研究人脑对信息加工、处理过程的科学。电脑实际上是仿人脑的 ,但是与人脑还有许多差别。地理思维在运用大脑时 ,比较全面 ,抽象思维、形象思维、和创造性思维 ,运用都很多 ,对开发大脑具有特殊的意义。文中概括地阐述了思维科学的主要内容 ,结合地理思维给出了具体的地理逻辑思维、地理图像思维和地理创造性思维的内容。 相似文献
586.
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588.
分析了规划信息在形式、内容上的复杂性,提出了Arc/Info平台下规则信息库的结构,讨论了在充分利用Arc/Info平台资源下,各数据文件在空间关系和属性层次上的结构化联系。 相似文献
589.
本文以区内岩矿石物性及地质资料为基础,对沽源—多伦地区航空磁场进行了分析和研究,依据磁场的分布特征及幅值大小将其划分为8个磁场分区,并对各分区磁场进行了地质解释,为在该地区应用航磁资料预测铀矿远景区提供了基础材料。 相似文献
590.
Several series of coordinated observations on decaying active regions and enhanced magnetic network regions have been carried out jointly at Big Bear Solar Observatory (BBSO) and Huairou Solar Observing Station of the Bejing Astronomical Observatory in China. The evolution of magnetic fields in several regions was followed closely for 3 to 7 days. The transport of magnetic flux from the remnants of decayed active regions was studied. Three related topics are included in this paper. (1) We studied the evolution and lifetime of the magnetic network which defines the boundaries of supergranules. The results are consistent with our earlier studies: network cells have an average lifetime of about 70 hours; 68% of new cells appeared by growing from a single network magnetic element; 50% of decaying cells disappeared by contracting to a network element. (2) We studied the magnetic flux transport in an enhanced network region in detail, and found the diffusion rate to be negative, i.e., there was more flux moving towards the decayed active region than away from it. We found several other cases where the magnetic diffusion rate does not agree with Leighton's model. The slow diffusion rate is likely due to the fact that the average velocity of larger magnetic elements, which carry most of the magnetic flux, is less than 0.1 km s–1; their average lifetime is longer than 100 hours. (3) We briefly described some properties of Moving Magnetic Features (MMFs) around a sunspot (detailed discussion on MMFs will be presented in a separate paper). In this particular case, the MMFs did not carry net flux away from the central spot. Instead, the polarities of MMFs were essentially mixed so that outflowing positive and negative fluxes were roughly balanced. During the 3-day period, there was almost no net flux accumulation to form a moat. The cancellation of MMFs of opposite polarities at the boundary of the super-penumbra caused quite a few surges and H brightenings. 相似文献