Mechanism of carbonate cementation and its influence on reservoir in Pinghu Formation of Xihu Sag

Carbonate cements are the most abundant authigenic mineral and impact on physical properties greatly in sandstone reservoir. In this paper, Pinghu Formation of Xihu Sag was taken as a target. Characteristics,distribution and formation of carbonate cements were investigated via optical microscopy, cathodoluminescence(CL), electron probe and in-situ carbon-oxygen isotope. The results showed that carbonate cements varied in types and shapes. Calcite/dolomite mainly present as poikilotopic cements, ...     

中尺度暖涡对热带气旋强度变化的影响及作用机制

基于两组理想化数值试验,对比研究了分布于热带气旋不同位置处的海洋中尺度暖涡所引发的热带气旋强度变化的时空特征。研究发现,热带气旋中心附近的暖涡对热带气旋强度有增强作用,而位于热带气旋外围的暖涡则会抑制热带气旋的发展。本研究将暖涡增强（减弱）热带气旋强度的区域称为内（外）区。随着时间的推移,内（外）区暖涡对热带气旋强度的增强（减弱）幅度逐渐减小（增大）,区域范围同步减小（增大）。内区暖涡增强了热带气旋的次级环流和结构对称性、增加了海气界面热通量,同时减弱了外围螺旋雨带,进而导致热带气旋强度增强;若暖涡在外区,其对热带气旋的作用相反,导致热带气旋强度减弱。由于理想化试验中热带气旋静止不动,因此研究结果可能只适用于传播速度较慢的热带气旋。本研究结果有助于更好地理解热带气旋和海洋中尺度暖涡之间的相互作用,并通过引入热带气旋外区暖涡的影响助力提高热带气旋强度预报工作。     

A terrain openness index for the extraction of karst Fenglin and Fengcong landform units from DEMs

The Fenglin and Fengcong landform units are considered to be an important representation for defining the degree of development of Karst landforms. However, these terrain features have been proven difficult to delineate and extract automatically because of their complex morphology. In this paper, a new method for identifying the Fenglin and Fengcong landform units is proposed. This method consists of two steps: (1) terrain openness calculation and (2) toe line extraction. The proposed method is applied and validated in the Karst case area of Guilin by using ASTER GDEM with one arc-second resolution. The openness of both the positive and negative terrain and a threshold were used to extract toe lines for segmenting depressions and pinnacles in Fenglin and Fengcong landforms. A comparison between the extracted Fenglin and Fengcong landform units and their real units from high resolution images was carried out to evaluate the capability of the proposed method. Results show the proposed method can effectively extract the Fenglin and Fengcong landform units, and has an overall accuracy of 93.28%. The proposed method is simple and easy to implement and is expected to play an important role in the automatic extraction of similar landform units in the Karst area.     

Investigations into the thermal non-equilibrium of W UMa-type contact binaries

Traditionally, some physical details(e.g., magnetic braking, energy transfer, angular momentum loss, etc.) have to be taken into consideration during investigations into the evolution of contact binaries. However, the real evolutionary processes which usually contain several of these physical mechanisms are very complicated as a result of strong interaction between components. To avoid dealing with these factors, a linear relationship is applied to the temperatures of components. It is found that the higher the mass ratio(M_2/M_1) of a contact system, the weaker the deviation from thermal equilibrium.On this basis, a variation trend of fill-out factor(f) changing with mass ratio can be inferred, which is consistent with observations. Moreover, if we stick to this point of view, it should be natural that the number of semi-detached binaries in the predicted broken-contact phase of relaxation oscillations is less than the number in the contact phase.     

面向作战任务的战场环境仿真过程对象模型

针对目前战场环境仿真系统与指控系统之间互操作性还不完善,需要构建一种面向作战任务的战场环境仿真过程模型来有效解析指控系统的关键信息需求。分析了仿真过程结构化特征,采用面向对象的方法构建仿真过程概念模型;分析GeoBML的数据模型和形式化语法,使用形式化语言建立仿真过程的逻辑语义模型;定义仿真过程对象数据结构,构建任务驱动下的仿真过程数据映射模型。最后,基于该模型设计战场环境仿真平台组件并应用,验证其合理性与可扩展性。     

Retrieval of atmospheric mass densities in lower thermosphere below 200 km from precise orbit of re-entry object CZ-3B R/B by analytical and numerical methods

Taking the re-entry object CZ-3B R/B (COSPAR identifier 2012-018D, NORAD catalog number 38253) as an example, retrieval of atmospheric mass densities in lower thermosphere below 200 km from its rebuilt precise orbit is studied in this paper. Two methodologies, i.e. analytical and numerical methods, are adopted in the retrieval. Basic principles of these two methodologies are briefly introduced. Based on the short-arc sparse observational data accumulated in the high accuracy re-entry prediction, orbit determinations of re-entry object CZ-3B R/B are performed sectionally, and then its precise orbit is rebuilt. According to the orbit theory, the variation of orbital semi-major axis of re-entry object CZ-3B R/B induced by atmospheric drag perturbation only is derived from the rebuilt precise orbit. In the derivation of secular change of the orbital semi-major axis of re-entry object CZ-3B R/B induced by atmospheric drag perturbation only, the time-span is set as one minute tentatively. And then retrieval results of atmospheric mass densities in lower thermosphere below 200 km by analytical and numerical methods are presented, as well as their bias deviations from the calculated results of the NRLMSISE-00 empirical model of the atmosphere. Setting bias deviation bands, the corresponding ‘confidence coefficients’ of the retrieved atmospheric mass densities with respect to the model values are given. Average bias deviations of the retrieved atmospheric mass densities by analytical and numerical methods from the model values are also calculated respectively. On the whole, the retrieved atmospheric mass densities by numerical method approach to the model values more closely; the differences between the retrieved results and the model values are relatively smaller at the peaks of atmospheric mass densities than the other places.     

不同应力状态下地层渗透系数的变化及其对流体运移影响的数值模拟研究

本文选择地层渗透系数受应力影响而变化作为研究流体运移的基础。压实固结和构造作用所产生应力对渗透系数影响的有限元数学模拟研究表明,平均有效应力与介质渗透性能呈负相关的变化趋势,应力驱动流体由应力高值区向应力低值区运移。     

近50年华南沿海SST热事件变化的时空特征

根据华南沿海10个海洋站1960-2009年实测海表温度(SST)资料统计分析了近50年华南沿海SST热事件时空变化特点,得出如下结论:华南沿海SST热事件主要出现在6-8月份,SST热事件出现的频率以北部湾东北部海域最高,粤东沿海最低;导致SST热事件海区差异的原因是上升流及热带气旋存在海区差异;受全球气候变暖的影响,华南沿海年均SST有上升趋势,近50年来气候变化可划分为冷、暖两个时期,其相对暖期SST热事件的年频数、累计天数、每次SST热事件持续天数较相对冷期均有增加趋势.     

印度暴力袭击事件的时空演变及其驱动机制

基于全球恐怖主义数据库（GTD）和南亚恐怖主义门户网站（SATP）所收录的印度暴力袭击事件数据,借助统计分析和核密度分析法,对1980—2017年印度暴力袭击事件时空演变及其驱动机制进行分析。结果表明：印度国内的暴力袭击事件频发,1980年以来呈现出波动上升态势。从空间上看,印度国内的暴力袭击事件具有自西到东、从北到南以及由边境地区向内地发展的扩散特点,展现出局部集中、面上扩散的发展趋势;呈现出以西北部的查馍-克什米尔地区和旁遮普邦、东北部的阿萨姆邦和曼尼普尔邦、中部的恰蒂斯格尔邦和东部的贾坎德邦、比哈尔邦和西孟加拉邦为主的四大集聚中心;形成以印度河上游—恒河—布拉马普特拉河一线为横轴,东高止山脉及其北部山区为纵轴的“T”字形空间格局。印度暴力袭击事件的时空演变受到身份认同、经济问题、历史问题和利益诉求等多方面因素的影响,通过宗教极端主义组织、民族分离主义组织、武装革命主义组织推动以及行动主体之间的互相作用,推动了暴力袭击事件的时空演变。要从根本上解决印度国内暴力袭击事件频发的态势,需要从政治、经济、宗教、社会等多方面进行综合施策。     

珠江口淇澳岛海岸带反硝化作用研究

采用N2通量法,在一套连续流动培养装置中测定珠江口淇澳岛海岸带的反硝化速率,探讨各种因素对淇澳岛海岸带反硝化速率的影响.结果表明,反硝化速率受NO3-的利用率影响,而不是NO3-的绝对浓度.大型红树植物对淇澳岛海岸带的反硝化速率影响最大,其次是硝酸盐利用率,而有机质含量的影响较小.由于大型红树植物的影响,样品Q0411-5的反硝化速率比同在岛内的Q0411-3高出1倍.样品Q0412-14的NO3-培养前后的浓度变化(△NO3-)是Q0412-9的4倍多,因为受硝酸盐利用率的影响,它的反硝化速率却是Q0412-9的2倍多.温度对反硝化速率的影响程度尚不能确定.