桂林旧石器时代晚期以来古人类生存环境研究

桂林是我国国家级历史文化名城,有着丰富的历史文化遗迹,其重要的文化特色就是遗存着大量的史前文化。目前,桂林发现最早的史前文化遗迹距今约为3.5万年。在研究桂林史前文化遗存的过程中,发现其有着独特的发展规律,如在重要气候转型期,桂林古人类的生活方式随之发生改变,这可能是受到当地环境和全球气候变化影响的结果。      

Progress of Research on Wind-blown Sand Prevention and Control of Railways in China

Based on the development of railways in desert areas of China, the types, characteristics, schemes, measures and technical systems of wind-sand disaster prevention and control were systematically analyzed in this paper. In view of the regional characteristics of sandy areas and the genres of railway sand damage in China, the results achieved and problems faced of wind-sand hazard and prevention technology in quicksand surface, plateau cold region and Gobi gale area were discussed as a case study. Combined with the expanding trend of railways in desert zone in China at present, starting from the theoretical research and the practice of sand control in engineering, it was proposed that the railway sand harm of complicated terrain and special environment is the key research direction in the field of wind-sand engineering in the future, which is also the crucial and difficult point in the protection and control of railway sand hazard in sandy zones.     

A Multiple Composite Fingerprinting Method and Its Application

Fingerprinting technique provides an essential means for estimating source contributions of watershed sediments, in which a single group of “optimum composite fingerprints” has been widely used in the literature to estimate sediment provenance. This type of methods is not restricted by the scale or process of sediment transportation so that similar procedures can be applied in sediment provenance research for aeolian depositions. However, recent studies found no direct link (positive relationship) between the ability of the tracer group to discriminate sources and its rigor in estimating source contributions after optimization. Here, we introduced a recently developed multiple composite fingerprinting method with additional screening based on analytical solutions, and further reviewed its verification in watersheds at different scales. It turned out that compared to Monte Carlo optimization method, a reasonable estimation can be achieved using the mean of the maximum number of composite fingerprints that given analytical solution to the mixing model, but the computational cost can be reduced significantly. The reliability of this new method was also tested in source contribution estimating of aeolian sediments, and the provenance quantification of reservoir sediment in an arid region experiencing both wind and water sediments.     

汶川8.0级地震前龙门山断裂带孕震构造运动特征分析?

On the basis of elastic rebound theory, using the horizontal velocity field of the Chinese mainland calculated from GPS data during three observation periods from 1999 to 2007, the velocity components that are parallel and plumb to the fault zone are calculated respectively for different periods, and then relative ground movements of two sides of the fault zone are analyzed with power function fitting and graphics. The results show that the relative ground movement shows right-lateral shear deformation before the Wenchuan Ms8. 0 earthquake, and at the same time the movement was hindered by the Longmenshan fault zone. Thus, this result has positive significance for distinguishing the elastic strain energy accumulation and deformation anomaly in an earthquake preparation process, and for conducting further research on earthquake prediction.     

永安地震台TJ-Ⅱ型体应变仪观测资料干扰分析

通过对永安地震台TJ-Ⅱ型钻孔体应变仪观测资料分析,总结日常观测可能遇到的多种干扰因素.从自然、仪器自身、人为干扰、外界环境等干扰因素的典型表现,加深对非地震前兆的干扰识别,以便更好地排除干扰,提高仪器观测资料质量.     

一种联合多历元观测信息的GPS/BDS组合单点定位方法

在GPS/BDS组合单点定位中,定位精度受观测信息量影响很大,但观测时段中不可避免地会有个别历元观测信息过少,导致这些历元的定位精度很差。基于此,本文提出了一种联合多历元观测信息的GPS/BDS组合单点定位方法,以弥补单历元方法中单个历元观测信息量不足的缺点。利用开阔环境和遮挡环境下的观测数据进行分析,结果表明,在GPS单系统、北斗单系统及GPS/BDS组合系统单点定位中,多历元方法的定位精度均优于单历元方法。     

冀东地区深孔地应力测量及其意义

为获得矿山深部开采和设计所需要的地应力基础资料,中国地质科学院地质力学研究所于2012—2013年在冀东地区滦县—乐亭大断裂附近开展了3个钻孔水压致裂的应力测量工作,钻孔孔深为500—1 000 m.地应力测量结果初步揭示了研究区地壳浅表层现今地应力的分布规律.实测结果表明:现今研究区域应力场优势方向为NW70°;3个测点的最大剪切应力与平均应力的比值um范围为0.24—0.48,平均值分别为0.30,0.40和0.30,均未达到地壳应力摩擦极限状态(um=0.6)的水平,而唐山大地震后不久研究区浅层获得的um则较大,个别点大于0.6,平均值为0.44,表明唐山大地震后研究区应力积累程度较低,应力释放较为充分;依据断层摩擦准则及拜尔利定律可知,研究区发生较大地震活动的危险性较低.