四川西昌盆地白垩纪恐龙足迹群的新发现

四川西昌盆地白垩系小坝组尚未发现骨骼化石记录,其白垩系恐龙动物群的信息全赖于足迹化石。2017年,在喜德县洛甘发现小坝组迄今最大型的恐龙足迹群。该足迹点保存了大量的兽脚类足迹。足迹保存条件较差,但具备了基本的形态学特征。总体来看,兽脚类足迹具有尺寸较小(8~13cm),中等中趾前凹(0.5~0.6)和第Ⅱ趾和第Ⅳ趾间较宽趾间角(70°~100°)的特征;少量足迹保存了跖骨垫。初步分析认为,洛甘兽脚类足迹与四川盆地夹关组的兽脚类足迹Eubrontes和Grallator形态类型相似,为两地在白垩纪中期具有类似的恐龙动物群的观点提供了新的证据。该发现对于西昌盆地的古气候、古地理和地层对比都具有重要的意义,足迹详细分类还有待进一步研究。     

新疆柯坪断裂带地震活动的特征及趋势分析

本文通过对1972年1月16日新疆西部柯坪地区6.2级的地震进行重点分析和总结,进一步扩大了研究地区,并从地震活动特征、发震的物理机制、波速变化以及当前的地壳运动等方面进行对比分析,对该地区地震趋势进行了初步探讨。     

基于DEM不同路径算法的沟壑密度提取

沟壑密度是评价小流域沟蚀程度的重要指标,同时也是反映地表破碎程度的因子。采用合理的汇流阈值设置方法,在黄土高原县南沟流域,通过基于坡向流量分配的多流向算法(DEMON)和传统的单流向算法D8实现沟壑密度的提取。结果表明:多流向算法和单流向算法都能提取较合适的沟壑密度,其中多流向算法提取的结果更好一些。因此,本研究对地表破碎程度的描述和当地地形地貌的反映有重要的意义。     

运用社交网络分析淹水空间信息之关联性

随着社交网络的普遍发展,大量的讯息透过智能手机发布在个人的微博或其他社交网站。台湾地区的社交网站以脸书(Facebook)的使用量最大,平均每天有近千万笔的讯息量,大多数的讯息多以食衣住行或个人讯息为主,但从本研究所撷取自2010年至2015年的数据中显示,公众在社交网站所分享的信息中具有降雨、淹水或相关灾情的讯息,而这些讯息具有极高比例的正确性。由于社交网站无法提供私人讯息,故本研究将从社交信息中,以地点为单位撷取大量的数据信息再辅以语意关键词萃取出有关可作为淹水预判的讯息数据。为检核资料的可性度,本研究透过历史台风数据FLO-2D仿真重建淹水之空间信息进行检核。从研究比对分析中发现,经萃取后的公众信息其与灾害的关联性及正确性相当显着,故透过社交网站中大量的非结构讯息,透过语意及空间的转换,可萃取转化为防灾信息,对广域的都市治理而言,此一讯息将可作为预判区域淹水或防救灾情报之有效参考。     

THE DOUBLE-LAYER STRUCTURE OF THE HADLEY CIRCULATION AND ITS INTERDECADAL EVOLUTION CHARACTERISTICS

Based on the three-pattern decomposition of global atmospheric circulation(TPDGAC), this study investigates the double-layer structure of the Hadley circulation(HC) and its interdecadal evolution characteristics by using monthly horizontal wind field from NCEP/NCAR reanalysis data from 1948—2011. The following major conclusions are drawn: First, the double-layer structure of the HC is an objective fact, and it constantly exists in April,May, June, October and November in the Southern Hemisphere. Second, the double-layer structure is more obvious in the Southern than in the Northern Hemisphere. Since the double-layer structure is sloped in the vertical direction, it should be taken into consideration when analyzing the variations of the strength and location of the center of the HC.Third, the strength of the double-layer structure of the HC in the Southern Hemisphere consistently exhibits decadal variations with a strong, weak and strong pattern in all five months(April, May, June, October, and November), with cycles of 20-30 a and 40-60 a. Fourth, the center of the HC(mean position of the double-layer structure) in the Southern Hemisphere consistently and remarkably shifts southward in all the five months. The net poleward shifts over the 64 years are 5.18°, 2.11°, 2.50°, 1.79° and 5.76° for the five respective months, with a mean shift of 3.47°.     

Breaking of Solitary Waves on Uniform Slopes

The propagation,shoaling and breaking of solitary waves on mild slopes are simulated byboundary element method.In this paper,the criterion of breaking solitary waves on mild slopes is discussed.The criterion is that the ratio of horizontal velocity of water particles on the wave crest to wave celerity equalsone.However,the case that the ratio of horizontal velocity of water particles on the wave crest to wave ce-lerity is below one but the front face of wave profile becomes vertical is also considered as a breaking criteri-on.According to the above criteria,the breaking index for slopes 1:10 to 1:25 is studied.The result is com-pared to other researchers'.The deformation of solitary waves on slopes is discussed and the distribution offluid velocities at breaking is shown.     

木钙对兰州黄土水理性质的影响

为揭示木钙对兰州黄土水理性质的影响,基于不同的木钙掺量和养护龄期,通过水滴入渗试验、渗透试验和崩解试验分析木钙土斥水性、渗透性和水稳性,并利用X射线衍射试验、扫描电镜试验探讨木钙土的改良机理。研究结果表明:木钙的掺入可以提升黄土的斥水性、水稳性,低掺量木钙土提升幅度有限,高掺量木钙土整体表现良好,而减弱渗透性的作用有限;木钙土的水理性质发挥具有龄期效应;28 d养护龄期下,木钙土的水理性质参数随木钙掺量的变化存在广义上的峰值,但峰值与木钙掺量的关系存在一定差异;木钙土的水理性质同力学性质保持了一定的正向关联性。木钙土并未产生新的矿物成分,但土颗粒双电层厚度变薄,而且胶结生成物包裹联结颗粒、填充孔隙,从而改善木钙土的水理性质。     

On-line estimation of unit hydrographs using the wavelet-based LMS algorithm / Estimation en ligne des hydrogrammes unitaires grâce à l'algorithme des moindres carrés moyens à base d'ondelettes

Abstract

This study applies the discrete wavelet transform (DWT) to decompose the unit hydrograph, thereby generating parsimonious reparameterizations of the unit hydrograph. A model compression method is then employed to significantly compress the unit hydrograph requiring that fewer coefficients be estimated. Moreover, a wavelet-based linearly constrained least mean squares (WLCLMS) algorithm is also used to estimate on-line the wavelet coefficients of the unit hydrograph. The updated wavelet coefficients of the unit hydrograph, convoluted with effective rainfall input in the wavelet domain, allow for accurate prediction of one-step-ahead runoff in the time domain. The proposed approach allows the unit hydrographs to vary in time and accurately predicts runoff from a basin in Taiwan, thus making it highly promising for flood forecasting.     

利用P波和S波的初动和振幅比计算中小地震的震源机制解

应用Snoke最新发展的利用P波、 SV波、 SH波的初动和振幅比联合计算地震震源机制解的程序, 使用一些省地震局数字台网得到的数字波形资料, 尝试计算了中小地震的震源机制解, 并与原来仅用P波初动得到的结果进行对比研究。 结果表明, 这种方法是可行的。 该方法为数字地震资料在地震预测中的应用提供了一种新的可能。