二维界面流的稳定性及相路方程的椭圆型条件          下载免费PDF全文

欧阳首承  朱克云 《大气科学》1991,15(1):74-83

针对天气实践的一些问题,本文改变了文献[1]的某些作法,分别就上、下行波的稳定性情况,切变邻近区域相路方程的类型条件作了较细致的讨论。结果表明:不稳定极易发生在背急流方向而立的左侧,并在不连续界面的两侧其稳定性是不同的,其相路方程也是有条件的——急流轴及其左侧邻近地区,一般满足椭圆型条件,而其右侧则有可能出现双曲型,从而揭示了扰动沿东西向传播时不稳定易于维持的原因,并与天气实践吻合。  相似文献   

“双碳”战略下废弃露天矿山生态修复模式研究与实践——以山东省废弃露天矿山为例          下载免费PDF全文

刘传娥  李生清  胡靖爽  蒋磊 《山东国土资源》2022,38(9)

本文通过研究山东省废弃露天矿山现状，分析存在的矿山地质环境问题。在总结以往废弃露天矿山生态修复情况的基础上，以“双碳”战略目标为引领，对废弃露天矿山生态修复所涉及的对象、技术、修复方向等进行了系统的研究，总结了生态复绿、农业用地、科普教育基地、旅游业用地、建设用地5种废弃露天矿山生态修复模式。以山东省废弃露天矿山生态修复经验为例，说明5种矿山生态修复模式在历史遗留废弃露天矿山生态修复工作中的实践应用。  相似文献   

大火成岩省及地幔动力学   总被引：4，自引：1，他引：4       下载免费PDF全文

赵海玲  狄永军  李凯明  李永华 《岩石矿物学杂志》2001,20(3):307-312

大火成岩省由一个体积巨大的、连续的、以富镁铁岩石占优势的喷出岩及其伴生的侵入岩组成，是一个全球现象。它包括大陆溢流玄武岩和伴生的侵入岩，火山被动边缘玄武岩，大洋高原、海岭、海山群和洋盆溢流玄武岩。Ontong Java和Kerguelen-Broken Ridge大洋高原、北大西洋火山被动边缘、德干和哥伦比亚河大陆溢流玄武岩是3个主要大火成岩省的典型代表。各种不同的大火成岩省在时空分布及组成上都具有相似性，它们具有非常大的体积、高的喷发速率，岩石类型以拉斑玄武岩为主。大火成岩省代表了地球上已知的最大的火山岩浆活动，记录了物质和能量从地球内部向外的大量转换。大火成岩省难以用板块构造来解释，可用热柱模式来解释，通常被认为是与来自下地幔的热柱“头”有关。大火成岩省是地球动力学过程在地壳的表现，因此大火成岩省参数可作为边界条件去反演地幔动力学过程。  相似文献   

ESRfrag: A new suite of open access programs for the efficient handling of Electron Spin Resonance spectra of enamel fragments     

《Quaternary Geochronology》2022

Accurate decomposition of Electron Spin Resonance (ESR) spectrum is a crucial task to extract compound signal intensities of enamel fragments at different irradiation time, in particular for dose recovery accuracy. While it can be achieved manually, the task is laborious and repetitive. In this paper, we present a new freely available program “ESRfrag” that allows the alignment, merging, and computation of complex angular ESR spectra. This program is an open access web-based code, designed to specifically alleviate the daunting task of working with large amounts of ESR spectra for enamel fragment dating. ESRfrag provides an increased reliability and precision on the results compared to manual calculation by removing operators bias. The program can be freely access through the Geoarchaeology and Archaeometry Research Group website (https://www.garg.org.au/projects).  相似文献   

ROSAT PSPC observations of the Orion Trapezium area II. Source variability and revised source list     

P. Lohmann  H.J. Wendker 《Astronomische Nachrichten》2000,321(2):81-100

A deep ROSAT PSPC image centred on the Orion Trapezium has been reduceda second time using an improved version of the PSF to fit the data. The outer rim of the field of view was also included. The new catalogue contains 316 X‐ray sources which are easily identified with pre‐main sequence stars of the Ori OB1 Ic and Id association. All 316 sources were tested for variability. No variations were found inside the single exposures of about 45 minutes length each. Between the 4 exposures spaced over 5 days about 1/3 of the sources show signs of activities of various forms. As above 25% of these have somewhat regular lights curves (monotonically rising or falling or hill‐shaped) we infer that at least some outbursts with time scales longer than a day are present and that past searches for X‐ray flares of pre‐main sequence stars were biased towards shorter time scales.  相似文献