Stability of the lundquist field and the physical nature of eruptive prominences with helical structure     

Ao-Ao Xu  Gui Ping Wu 《Solar physics》1995,159(2):265-273

The stability of the Lundquist field is analysed in the light of the energy principle. The results show: (1) form = 0 disturbances, the Lundquist field is stable; (2) form = 1 disturbances, the Lundquist field will turn unstable in certain conditions. Whether the field will remain stable or not depends on parameters such as the helical pinch angle and radius and length of the prominence. Comparison between theory and observations reveals that a kink instability in the Lundquist field may be a critical physical reason for eruptive prominences with helical patterns.  相似文献   

基于GIS的淤泥质潮滩侵蚀堆积空间分析   总被引：13，自引：0，他引：13  

李恒鹏  杨桂山 《地理学报》2001,56(3):278-286

通过野外滩地长期水准详测资料，利用地理信息系统的GRID和TIN模块产生潮滩高程、坡度、二维剖面、侵蚀与堆积分布图，并获取测点所在位置的高程、坡度和侵蚀量，对获取的数据及空间分布图进行分析，结果表明：侵蚀主要发生在-7m以上的岸坡和潮滩，堆积主要出现于广阔的深水岸坡和7部分高滩，侵蚀速率以滩前深槽岸坡最快，年侵蚀率达17.9cm/a，并呈加速趋势，海岸线向陆后退速率为31m/a，侵蚀、堆积的闭合深度约为-9.5m，空间分布表现为自北而南的3个明显分带，即潮滩轻微侵蚀区，滩前深槽岸坡强烈侵蚀区和深水岸坡缓积区，东西向比较，东部，中部侵蚀大于西部。  相似文献   

华南新元古代裂谷盆地演化——Rodinia超大陆解体的前奏   总被引：26，自引：0，他引：26  

王剑  刘宝珺  潘桂棠 《矿物岩石》2001,21(3):135-145

沉积学研究表明，华南新元古代沉积盆地具典型裂谷盆地沉积演化特征。代表裂谷盆地早期形成阶段的成因相组合有：冲洪积相组合、陆相（或海相）火山岩及火山碎屑岩相组合、滨浅海相沉积组合、淹没碳酸盐台地及欠补偿盆地黑色页岩相组合；而代表中、后期形成阶段的成因相组合有：滨岸边缘相至深海相组合，冰期冰积岩相组合、碳酸盐岩及碳硅质细碎岩相组合。华南裂谷盆地岩相古地理演化经历了5个重要的时期，整体上反映了一个由陆变海、由地堑－地垒相间盆地变广海盆地、由浅海变深海、盆地上小变大的演化过程。裂谷盆地的形成经历了裂谷基的形成、地幔柱作用与裂谷体的形成，被动沉降（下坳）与裂谷盖的形成三个阶段。华南裂谷盆地的形成演化与Rodinia超大陆在新元古代时期的裂解作用密切相关，它是超大陆解体过程的一个重要组成部分。  相似文献   

选取岭参数的一个新方法   总被引：2，自引：1，他引：1  

归庆明 《测绘工程》1997,6(1):14-19

当法方程的系数阵呈病态时,平差参数的最小二乘估计不再是一个良好好估计。为改进最小二乘估计,许多学者提出众多的有偏估计方法,其中影响最大的是岭估计和主要估计。  相似文献   

Calcium Isotopic Fractionation during Ion‐Exchange Column Chemistry and Thermal Ionisation Mass Spectrometry (TIMS) Determination          下载免费PDF全文

Hong L. Zhu  Zhao F. Zhang  Gui Q. Wang  Yu F. Liu  Fang Liu  Xin Li  Wei D. Sun 《Geostandards and Geoanalytical Research》2016,40(2):185-194

Significant isotopic fractionation can occur during column chemistry and determination by mass spectrometry. Improper correction may produce uncertainties in the isotopic composition of geological samples. We investigated calcium isotopic fractionation during these two processes and set up a model to check data quality. The δ^44/40Ca_915a value of IAPSO seawater in different Ca cuts (e.g., 0–20, 20–40, 40–60, 60–80 and 80–100%) on column chemistry ranged from ~ 4‰ to 0‰. The more Ca was eluted, the lower the δ^44/40Ca_915a value of the elution was found. The isotopic fractionation of calcium on the column appeared to follow the exponential law. However, TIMS instrumental fractionation during Ca runs did not always follow the exponential law due to mixing effects from sample reservoirs on the filament. Our results show that errors could be caused if the instrumental fractionation deviates from the exponential law, especially when the fractionation degree is large. To improve the measurement uncertainty, a model is proposed to check the behaviour and degree of instrumental fractionation, which will provide a quick and reasonable verdict on the data quality of TIMS runs.  相似文献   

Comparison of ground temperature response of energy pile and borehole heat exchanger during thermal response tests     

Jin Luo  Haifeng Zhao  Shuqiqang Gui  Wei Xiang  Joachim Rohn 《Environmental Earth Sciences》2016,75(22):1463

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Practice and research progress on ecosystem conservation in transboundary areas     

Lina Tang  Liuming Gui  Guofan Shao  Luyan Wang  Longyu Shi 《中国地理科学(英文版)》2016,26(1):109-116

Many ecosystems extend across national or political boundaries. The consistent and effective protection of these ecosystems in transboundary areas(ETAs) is an important global research focus. Previous research on the protection of such areas can be categorized into seven themes: 1) ecological conservation of a single ETA; 2) investigation of the effects of a single conservation measure on a specific ETA; 3) determination of species-level effects due to ETA conservation; 4) comparison of the same protection measures between different ETAs; 5) introduction of a single conservation measure to a specific ETA; 6) understanding the relationship between conservation and sustainable development; and 7) generalization across multiple ETA conservation cases. The protection of ETAs involves various considerations, including funding support, demand and will for collaboration, community and public participation, historical and cultural factors, political backgrounds, uniqueness of biological resources, formulation of laws and regulations, founding of specialized administrative departments, non-governmental organizations, and fairness. Here, we briefly explain the research themes and considerations related to ETA conservation. The most important finding is that most major research themes do not focus on the challenges of ETA conservation. We use two nature reserves located between China and North Korea as examples to identify specific ways to improve ETA conservation on Changbai Mountains. The efficiency of ETA administration still remains low. The study of ETA conservation should focus on concrete regional information and aim to improve existing measures through the accumulation of experience.  相似文献   

An Extension Mechanism to Verify,Constrain and Enhance Geoprocessing Workflows Invocation   总被引：1，自引：0，他引：1       下载免费PDF全文

Kunlun Qi  Zhipeng Gui  Zhenqiang Li  Wei Guo  Huayi Wu  Jianya Gong 《Transactions in GIS》2016,20(2):240-258

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珊瑚荧光的古降水记录   总被引：3，自引：0，他引：3  

贺剑峰  彭子成  何学贤  张兆峰  刘桂建 《海洋地质与第四纪地质》2001,21(2):63-68

珊瑚作为热带海洋气候环境的信息载体，不仅记录了过去海洋信息，也记录了陆源环境信息。Isdale于1984年在《Nature》杂志上发表论文阐明珊瑚的黄绿荧光记录了Burdekin河的径流量变化以后，国际上对珊瑚荧光的研究逐渐发展起来，并取得了不少成果。研究表明，利用珊瑚荧光所提供的信息，可以重现过去大陆沿海的降雨变化情况、干旱或洪涝的变化旋回及入海河流的径流量变化。这对研究并重建过去气候环境、预报未来的气候变化趋势有着重要的意义。本文评述了国外对珊瑚荧光的研究进展、报道了本实验室进行了初步工作，同时，对珊瑚荧光作为环境地球化学新的代用指标所潜在的应用前景进行了讨论。  相似文献   

锯缘青蟹胸神经团的免疫细胞化学定位研究   总被引：4，自引：0，他引：4       下载免费PDF全文

黄辉洋  叶海辉  李少菁  王桂忠  金朱兴 《海洋科学》2003,27(3):77-80

采用兔抗哺乳类抗血清，应用链霉菌抗生物素蛋白-过氧化物酶免疫细胞化学技术，研究了锯缘青蟹（Scylla serrata）胸神经团中5-羟色胺（5-HT）、胰高血糖素（Glu）和神经肽Y（NPY）的分布。其分布的主要特征为：5-HT免疫阳性细胞在每对步足神经节都呈对称排列；GLU免疫阳性最强，胸神经节的阳性细胞排列成两条环境胸动脉孔分布的细胞带，神经髓质中免疫阳性物质呈斑块状分布；NPY阳性细胞主要分布于食道下神经节。这3种免疫阳性物质的特定分布模式可为腹神经链的系统演化和参与神经活动提供形态学证据。  相似文献