计算河流动力学理论体系框架探讨

计算河流动力学重在研究河流动力的时空变化,实质上是计算流体力学、计算土力学在河流动力学中的应用,但并非简单组合,主要难点源自相间作用机理复杂性及研究对象多尺度性所导致的应用可行性问题。问题解决的过程中产生大量新的适于河流动力计算的数学模型和数值模型,但当前理论体系还缺乏系统性。综合河流动力学、计算流体力学、计算土力学理论,给出计算河流动力学的理论体系框架,明确计算河流动力学各部分内容的基本联系。基于此理论体系,可以方便地判断模型准确性、计算量和复杂性,构建最优的数学模型,并判断数学模型的发展方向。     

基于GIS的青岛市工程场地评价可视化研究

本文主要完成了以下几大模块:①以规范模型为基础,首先智能判别单个钻孔的场地所属类别和砂土液化情况,然后采用插值方法插值成面状场地类别分区和砂土液化分区图,并动态加以展示;②根据先前输入的钻孔资料信息自动生成基岩顶部等值线图;③根据资料得到青岛市断层分布,然后依据规范规定,应用缓冲技术给出建筑避让距离;④展示所应用的判别规范,允许用户添加和更改。根据以上几点处理,基本达到了工程场地评价的可视化,为相关部门提供了方便工具和直观资料。     

Post‐orogenic evolution of the Mesozoic Micang Shan Foreland Basin system,central China

[Correction added after online publication 3 August 2010 ‐ ‘prelate’ has been changed to ‘pre‐late’ throughout the text]. Using apatite fission track and (U‐Th‐Sm)/He thermochronology, we report the low‐temperature thermal history of the Mesozoic Micang Shan Foreland Basin system, central China. This system, comprising the Hannan Dome hinterland, the northern Sichuan Foreland Basin and the intermediate frontal thrust belt (FB), shares a common boundary with three major tectonic terrains – Mesozoic Qinling‐Dabie Orogen, Mesozoic Sichuan Foreland Basin and Cenozoic elevated Tibetan Plateau. Results show: (1) a relatively rapid pre‐late Cretaceous cooling episode in the Hannan Dome; (2) a mid‐Cenozoic cooling phase (ca. 50°C at ca. 30 ± 5 Ma) within the northern Sichuan Basin; and (3) possible late Cenozoic cooling (ca. 25°C at ca. 16 ± 4 Ma) within the Hannan Dome‐FB, a phase which has also been reported previously from adjacent regions. The pre‐late Cretaceous cooling episode in the Hannan Dome is attributed to coeval tectonism in nearby regions. Mid‐Cenozoic cooling in the northern Sichuan Basin can possibly be attributed to either one of or a combination of shortening of the basin, onset of the Asian monsoon and drainage adjustment of the Yangtze River system, all of which are related to growth of the Tibetan Plateau. Possible late Cenozoic cooling in the hinterland and nearby regions is also probably related to the northeastward growth of the Tibetan Plateau. However, previous studies suggest a northeastward propagation for onset of cooling from the eastern Tibetan Plateau to western Qinling in response to northeastward lower crust flow from the central Tibetan Plateau. The timing of apparent late Cenozoic cooling in the Hannan Dome hinterland, at an intermediate locality, is not consistent with this trend, and supports a previous model suggesting northeastern growth of the Tibetan Plateau through reactivation of WE trending strike‐slip faults.     

Salinity Variability and Water Exchange in Interconnected Estuaries

A high-resolution coastal ocean model is used to investigate salinity variability and water exchange in a complex coastal system off the southern U.S. characterized by three adjacent sounds that are interconnected by a network of channels, creeks, and intertidal areas. Model results are generally highly correlated with observations from the Georgia Coastal Ecosystem Long Term Ecological Research (GCE-LTER) program, revealing a high degree of salinity variability at the Altamaha River and Doboy Sound, decreasing sharply toward Sapelo Sound. A Lagrangian particle tracking method is used to investigate local residence time and connectivity in the system. Local residence time is highly variable, increasing with distance from the Altamaha River and decreasing with river flow, revealing that discharge plays a dominant role on transport processes and estuary-shelf exchange. The Altamaha River and Doboy Sound are connected to each other in all seasons, with exchange occurring both via coastal and estuarine pathways. While particles released at the Altamaha and Doboy rarely reach Sapelo Sound, particles released at Sapelo Sound and the creeks surrounding its main channel can reach the entire estuarine system.     

地学数据共享网用户Web行为预测及数据推荐方法

网络环境下,如何让用户快速发现所需数据是地学数据共享平台长期面临的挑战之一。本文基于国家地球系统科学数据共享平台网站服务器日志数据获取用户搜索行为及数据集访问行为,使用聚类算法挖掘用户行为模式,并基于会话聚类 模式开发在线搜索和访问预测算法。在数据预处理阶段,对原始服务器日志数据进行清洗、用户识别、用户会话识别、搜索词提取。在模式挖掘阶段,采用DBSCAN算法对会话进行聚类。考虑到会话向量值的二元性,聚类算法中的距离采用Jaccard距离函数计算。视每个会话聚类包含的搜索词集合为一个文本,所有用户历史搜索词集合为语料库,统计各聚类中搜索词的TF-IDF值。在线搜索推荐,以搜索词检索各聚类中TF-IDF值,返回TF-IDF值最高的搜索词所属聚类,并给出该聚类的高频项目作为推荐。在线访问推荐,则以用户实时访问向量为查询向量,计算该向量与聚类中心的聚类。根据聚类排序,给出距离最近的聚类,并产生该聚类中高频项目作为推荐。实验结果表明基于TF-IDF和聚类的搜索推荐有较高的准确率和召回率,访问推荐效果基于高频统计的推荐有较大提高。研究可得出以下结论：① 地学共享网用户访问和搜索行为体现了专业性的特点,其行为较普通网站用户可预测性更好;② 对于地学数据共享用户行为预测,需明确定义用户行为,并采用合适的距离函数描述行为相似性;③ 通过搜索词TF-IDF值来预测用户数据需求的方法可行,以此产生的推荐可作为搜索结果的补充。本研究可服务于地学领域数据共享平台建设,提高共享服务质量,也可为其他领域科学数据共享提供技术方法借鉴。     

Analysis of topography,heat flow against crustal age in the Southwest Subbasin,South China Sea

ABSTRACT

The relationships in ocean depth and heat flow with crustal age place valuable constraints on the thermal evolution of the oceanic lithosphere. This work aims to establish the relationships for the V-shaped Southwest Subbasin, the southwestern end of the South China Sea formed during 23.6–16 Ma. Using high-resolution multichannel seismic profiles and heat flow measurements, we calculate sediment-corrected topography and heat flow, which are then plotted against crustal age to establish their relationships. The results show that the post-spreading volcanism in the South China Sea influences less on the present-day heat flow than topography. In addition, the topography data are evidently deeper and heat flow data are much lower in the Southeast Asian marginal seas than other oceans. Previous explanation suggested that the abnormal features resulted from lateral heat loss, which would predict a deeper lithosphere–asthenosphere boundary and a high slope in topography and heat flow with age, contrary to the observations. Possible explanations for the abnormal features of the Southeast Asian marginal seas include (1) lack of long-time upwelling magma at the onset of spreading, and (2) reduced magma supply during the seafloor spreading.     

溶洞穴滴水元素季节变化及其气候指示意义研究—以贵州省麻黄洞为例

为揭示岩溶洞穴滴水元素季节变化特征及其对外界气候环境变化的响应关系,对贵州绥阳双河洞系支洞麻黄洞内3处滴水的Mg、Ca、Sr元素进行了为期13个月的监测。结果显示:(1)3个滴水点M1、M2和M3的水化学类型主要为HCO3·Ca型,岩溶水对于方解石与白云石等矿物的溶解处于饱和状态;(2)上覆土壤和岩层厚度逐渐增加,导致水-土-岩作用时间也随之增加;(3)Ca^2+、Mg^2+、Sr^2+浓度变化总体上呈逐级递增的特点,各离子浓度在高温多雨季节波动幅度大,低温少雨季节变化平稳;(4)Mg/Ca、Sr/Ca均表现出雨季低、旱季高的特征,反映该地区外界干湿条件的变化;(5)由模型模拟显示,3个滴水点皆以PCP/ICD作用为主,M1对降雨响应不敏感,M2滴率与离子浓度呈雨季高、旱季低的变化规律,M3位于洞穴最深、顶板最厚处,滴率与离子浓度无显著季节变化特征。结合各滴水点洞穴环境变化规律,推断M2更能准确响应外界气候环境变化。     

Fundamentals and Applications of Raman Spectroscopy of Carbonaceous Material(RSCM)Thermometry

This contribution attempts to summarize the principles, sample preparation, analytical procedures, influencing factors, and geological applications of Raman Spectroscopy of Carbonaceous Material (RSCM) thermometry. Irreversible graphitization of carbonaceous material in sedimentary rocks occurs during the process of reaching peak metamorphic temperature and can be effectively quantified by Raman spectroscopy. However, in addition to temperature, other factors, such as structural and compositional heterogeneity of carbonaceous materials, structural damage caused by polishing, wavelength and energy of laser used for analyses, hematite content,etc., also have significant influence on the Raman signals of carbonaceous materials. Therefore, fresh samples should be collected for analyses to eliminate the influence of hematite. Further, standard experimental procedure should be practiced to avoid the effects of polishing and laser parameter setups. Additionally, multiple (usually more than 25) analyses per sample should be carried out for deriving statistical average and uncertainty values so as to minimize the influence of sample heterogeneity. RSCM thermometry is applicable to a temperature range between 100~700 ℃, and has been widely used in many fields of geological studies, including metamorphism and deformation of orogens, sediment burial history, fault gouge characteristics and evolution, and maturation grade of carbonaceous materials,etc.     

深海适冷菌SM9913产生的低温蛋白酶

从1855m深的深海泥样中分离纯化得到200多株分泌蛋白酶的适冷菌，其中3株产低温蛋白酶，本文对其中一株Pseudomonas sp.SM9913(P.SM9913)生长的适冷性和它产生的蛋白酶的适低温特性进行了研究。该菌株能够在0℃正常生长，其最适生长温度为15℃，最高生长温度为35℃。为一株适冷菌。该菌株所产蛋白酶的比合成速率在10℃时最高，催化酪蛋白水解的最适温度为35℃，在0℃仍具有3％的酶活力。最适pH为8．0。该蛋白酶的热稳定性很低，在40℃保温10min即丧失85％的活力，40℃时的半衰期为6min，为一典型的低温酶。抑制剂试验表明，该蛋白酶为金属蛋白酶。