用日全食光谱探测太阳中低层大气对局部热动平衡的偏离          下载免费PDF全文

刘曦  屈中权  宋智明 《天文学报》2021,62(1):9-109

在太阳大气不同层次连续光谱中叠加有丰富的发射线或吸收线,对这些谱线轮廓进行反演分析可以探测太阳大气的化学成分和物理状态.太阳大气的色球及过渡区由于其密度低难以建立热动平衡,建立相应的大气模型需要采用非局部热动平衡(Non-Local Thermodynamic Equilibrium,N-LTE)理论.根据相对偏离因子计算来研究太阳中低层大气偏离局部热动平衡(Local Thermodynamic Equilibrium,LTE)分布的情况.首先对日全食观测过程中得到色球和过渡区不同高度形成的两条光谱数据进行反演,得到确定观测谱线的参数信息,如连续谱源函数、谱线源函数、多普勒宽度和由此推出的等效动力学温度;根据这些反演出的谱线参量计算出二维视场内每个空间采样点偏离LTE状态的定量结果;其次,根据用于观测的积分视场单元光纤排布阵列重构出辐射强度、等效动力学温度和相对偏离因子二维分布.结果显示:在局部小区域,温度分布和相对偏离因子的分布存在较强相关性,而与辐射强度分布无明显相关.从两条谱线导出的等效温度和相对偏离因子分布存在明显的差异.这两种二维分布揭示出太阳大气某些小尺度区域具有较强的结构性和复杂性,为进一步理解太阳中低层大气物理提供了一种新的视角.  相似文献   

国内外绳索取心钻具研发应用概况及特深孔钻进问题分析   总被引：1，自引：1，他引：0       下载免费PDF全文

李鑫淼  李宽  孙建华  梁健  尹浩 《探矿工程》2020,47(4):15-23，39

随着钻孔深度的不断增加，对绳索取心钻具的使用性能提出了更高要求。在分析了国内外绳索取心钻具研发现状、结构设计特点及特深孔应用情况的基础上，整理了特深孔钻进绳索取心钻具使用存在的技术问题，定位机构打捞可靠性、到位报信提示可靠性、堵心报信机构工作稳定性、单动机构使用寿命均有待提高，并相应地分析了原因，为5000 m特深孔绳索取心钻具优化设计打好基础。  相似文献   

滇西南钾盐调查MK-3大口径超深井绳索取心钻进工艺          下载免费PDF全文

吕利强 《探矿工程》2020,47(3):53-58

滇西南中生代盐盆地钾盐资源调查评价项目MK-3井，设计井深2700 m，全孔取心，岩心直径≮80 mm，一般井段岩心采取率达到80%以上，盐岩段岩心采取率＞95%。工程技术要求高，施工难度大。施工中遇到了地层坍塌、涌水、掉块、盐岩溶蚀等问题，通过采用氯化镁饱和盐水冲洗液，HXY-9B型钻机取心钻进、TSJ-2000型水源钻机扩孔钻进，分级下管隔离等措施，圆满完成了钻探任务。完钻井深2701 m，岩心采取率90%，盐岩段岩心采取率达98.65%，终孔口径127 mm，岩心直径81 mm。经地球物理测井，各项指标都达到了设计要求。刷新了国内CHD127标准绳索取心钻杆P口径钻探深度的记录。  相似文献   

关于确保甘肃省祁连山生态保护红线落地并严守的科技支撑建议   总被引：1，自引：0，他引：1  

王宝  王涛  王勤花  王鹏龙  徐冰鑫  高峰 《中国沙漠》2019,39(1):7-11

祁连山是中国西部重要生态安全屏障，是国家重点生态功能区，其生态保护与治理一直受到国家、地方政府和当地居民高度关注。目前，在祁连山的生态保护工作中，缺乏对现状基础数据的全面掌握，区域经济发展与生态环境保护矛盾突出，生态环境综合监测系统不完备，生态补偿机制推进实施缺乏创新。在全面梳理祁连山目前存在的重大生态问题的基础上，提出了祁连山生态保护红线落地并严守的建议，包括加快开展祁连山综合科学考察、完善并落实开展生态补偿机制、探索以正面清单为导向的协调发展模式、促进生态安全与地方经济社会可持续发展相协调、进一步实施重大配套政策、完善保障支撑体系等。  相似文献   

加权EIV模型的经典最小二乘算法     

谢建  龙四春 《大地测量与地球动力学》2019,39(5):544-546

采用GHM方法将EIV模型在最优解处线性化，得到解的近似方差。然后，将EIV模型表达成与Gauss-Markov模型相似的形式，利用标准最小二乘理论推导EIV模型的解及近似方差矩阵，得到与已有算法等价的结论。最后，推导观测值估值和残差的统计性质，建立起一整套EIV模型参数估计和精度评定的体系。  相似文献   

Location and probability of shoal margin collapses in a sandy estuary          下载免费PDF全文

Wout M. van Dijk  Dick R. Mastbergen  Geeralt A. van den Ham  Jasper R. F. W. Leuven  Maarten G. Kleinhans 《地球表面变化过程与地形》2018,43(11):2342-2357

Channel bank failure, and collapses of shoal margins and beaches due to flow slides, have been recorded in Dutch estuaries for the past 200 years but have hardly been recognized elsewhere. Current predictions lack forecasting capabilities, because they were validated and calibrated for historic data of cross‐sections in specific systems, allowing local hindcast rather than location and probability forecasting. The objectives of this study were to investigate where on shoal margins collapses typically occur and what shoal margin collapse geometries and volumes are, such that we can predict their occurrence. We identified shoal margin collapses, generally completely submerged, from bathymetry data by analyzing digital elevation models of difference of the Western Scheldt for the period 1959–2015. We used the bathymetry data to determine the conditions for occurrence, specifically to obtain slope height and angle, and applied these variables in a shoal margin collapse predictor. We found 299 collapses along 300 km of shoal margin boundaries over 56 years, meaning that more than five collapses occur on average per year. The average shoal margin collapse body is well approximated by a 1/3 ellipsoid shape, covers on average an area of 34 000 m² and has an average volume of 100 000 m³. Shoal margin collapses occur mainly at locations where shoals take up a proportionally larger area than average in the cross‐section of the entire estuary, and occur most frequently where lateral shoal margin displacement is low. A receiver operating characteristic curve shows that the forecasting method predicts the shoal margin collapse location well. We conclude that the locations of the shoal margin collapses are well predicted by the variation in conditions of the relative slope height and angle within the Western Scheldt, and likely locations are at laterally relatively stable shoal margins. This provides hypotheses aiding the recognition of these features in sandy estuaries worldwide. Copyright © 2018 John Wiley & Sons, Ltd.  相似文献   

地幔上涌对鄂尔多斯西缘岩石圈的改造:来自远震多尺度层析成像的证据   总被引：4，自引：1，他引：3       下载免费PDF全文

高翔  郭飚  陈九辉  刘启元  李顺成  李昱 《地球物理学报》2018,61(7):2736-2749

本文利用喜马拉雅二期科学探测台阵的678个地震台站及26个固定台站记录到的9，641个地震共约160000条远震P波走时数据，采用基于稀疏约束的多尺度层析成像方法，获得了鄂尔多斯西缘及邻区上地幔800 km深度范围内P波速度结构.结果显示，在东经104°附近阿拉善地块与鄂尔多斯盆地间存在岩石圈深度的构造边界，这表明阿拉善地块与鄂尔多斯可能分别从属于不同的大地构造单元.以北纬38°线为界，鄂尔多斯地块西缘在岩石圈范围内南北存在明显的速度差异，鄂尔多斯南部上地幔200~300 km深度范围显示为高速异常，而鄂尔多斯北部上地幔显示大面积的低速异常.这一现象表明，鄂尔多斯地块南北两部分经历了不同的构造演化过程.根据本文的结果可以进一步推断，由于青藏高原、阿拉善地块向东北方向推挤以及岩石圈的拆离引起的上地幔扰动导致了地幔上涌，上涌的热物质改造了鄂尔多斯西北缘地区的岩石圈，并使该区的岩石圈减薄.地幔上涌也可能是东经104°边界带和北纬38°构造带形成的深部动力学因素.  相似文献   

海洋功能区划与海洋生态红线关系探讨          下载免费PDF全文

高月鑫  曾江宁  黄伟  陈全震  寿鹿  徐晓群 《海洋开发与管理》2018,35(1):33-39

海洋生态红线制度是我国"五位一体"文明建设的具体要求。为进一步在自然科学与人文科学的联结点上探求深入开展生态红线工作的可能性,文章对比了实施多年的海洋功能区划与历史新阶段提出的海洋生态保护红线的概念和内涵,剖析了两者之间的区别与联系,指出海洋功能区划与海洋生态红线区划在法律地位和管控制度等方面具有一致性,在划分目标、空间管理及划分方法上具有差异性,海洋功能区划以"使用"为主,海洋生态红线以"保护"引领。在此基础上,建议未来海洋生态红线工作的开展可从海洋功能区划借鉴经验,建立完善的管控评估制度,确立生态保护红线的优先地位,处理好海洋功能区划与海洋生态红线区划的关系。同时,海洋生态红线区划应以维持海洋生态系统结构稳定和提高海洋生态系统服务功能为目标,将区域资源环境承载力评估作为一项参考指标,限制低承载区的开发利用,保证海洋生态环境健康可持续发展。  相似文献   

A SYSTEM OF CAPACITIVE HIGH-VOLTAGE PULSE RECHARGE/DISCHARGE AND ITS IMPLICATION ON EXPERIMENTALLY TRIGGERED EARTHQUAKE     

ZHANG Zhi-he  GUO Yan-shuang  CHEN Shun-yun 《地震地质》2018,40(6):1417-1426

An external small disturbance may trigger seismic events when the fault is in a critical state. The problems related with earthquakes triggered by the dynamic stress such as blasting loads, impact loads, volcanic eruptions and strong earthquakes, have usually drawn wide concerns in earthquake science, and the corresponding research contents are quite extensive, including earthquake triggering mechanisms, triggering earthquake uncertainty, aftershock triggering, and so on. Among them, experimental research is an important way to understand the stress triggering conditions and physical mechanisms, such as the influence of load disturbance on fault friction traits, the influence of periodic disturbance of tidal stress on fault instability, etc., all of which can be gained through experimental investigations. Among them, "how to trigger" is a basic scientific problem to increase the understanding of earthquake prediction theory, thus receiving more attention. There are also some studies that focus on "what happened after the trigger", that is, the sliding instability generated by the triggering method, and then the evolution characteristics of the sliding instability process. The well-known experimental study of the super-shear rupture process is conducted by using the electric explosion method to trigger the fault instability, and the high-speed camera records the super-shear rupture during the fault instability. This means that when the trigger source is controllable, it is possible to generate different types of instability processes, and then to explore which earthquakes will be triggered at different time and space positions under different stress states by means of active triggering. The study of stability analysis and instability process has important scientific significance.A stable system of capacitive high-voltage pulse discharge and recharge is one of basic techniques for studying the triggered earthquakes in laboratory. Based on the wire electric explosion method, this paper develops a controllable trigger experiment system. By designing a new capacitive high-voltage pulse charge and discharge system, while considering the actual needs of monitoring and system timing, multiple functions are integrated into one system. Functionally, in addition to realizing the dynamic loading and unloading function of the wire electric explosion method, the discharge process can be monitored, and the triggering, synchronization and timing signal output is performed with other observation systems, thus realizing the whole process monitoring of the dynamic disturbance action. After testing, the following functions are achieved:1)The voltage and current of the high-voltage charging power supply system can be automatically adjusted, and the system can be shut off after charging; 2)Control modes include manual and remote controls. These two modes can control the recharge, release and pulse discharge of the high voltage capacitor; 3)The system can produce multi-channel synchronous output, which satisfy multiple systems working together. In particular, the remote sensing method greatly improves the experimental maneuverability and security; 4)The system has multiple sets of gas discharge tube to trigger discharge, with a wide range of discharge voltage of 500~5 000V; 5)Roche coil resistance integral current detection can meet the transient resistance, large current detection. Test results indicate that this system has good repeatability and stability with the same discharge energy and discharge energy regulator, which is conducive to carry out single channel trigger of high-pressure discharge experiment. In short, the new charging and discharging system can meet the requirements of experimental study of triggering earthquake. In addition, this system can be used to generate the stress disturbance under certain static and dynamic conditions, and then judge whether this kind of mechanical conditions in active fault systems is currently stable.In short, a controllable single-shot discharge system is developed by a capacitive high-voltage pulse discharge system, which provides a good technical basis for experimental research on triggering earthquakes. In addition, the new system also has application significance:1)multiple triggering output can simultaneously start multiple systems and improve the efficiency of observation. Fault instability is a characteristic of transient response, so, its observation requires high-speed acquisition equipment, which is difficult to control on observation; the trigger system is controllable, with active synchronization observation using physical parameters; 2)stress disturbance can be triggered under static and dynamic loads to detect the safety and stability of the fault system with active trigger.  相似文献   

Character and origin of De Geer moraines in the Seacoast region of New Hampshire,USA          下载免费PDF全文

Samantha N. Sinclair  Joseph M. Licciardi  Seth W. Campbell  Brian M. Madore 《第四纪科学杂志》2018,33(2):225-237

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