基于经验模态分解的分数维地震随机噪声衰减方法

经验模态分解算法（EMD）是一种基于有效波和噪声尺度差异进行波场分离的随机噪声压制方法,但由于实际地震数据波场复杂,导致模态混叠较严重,仅凭该方法进行去噪很难达到理想效果.本文基于EMD算法对信号多尺度的分解特性,结合Hausdorff维数约束条件,提出一种用于地震随机噪声衰减的新方法.首先对地震数据进行EMD自适应分解,得到一系列具有不同尺度的、分形自相似性的固有模态分量（IMF）;在此基础上,基于有效信号和随机噪声的Hausdorff维数差异,识别混有随机噪声的IMF分量,对该分量进行相关的阈值滤波处理,从而实现有效信号和随机噪声的有效分离.文中从仿真信号试验出发,到模型地震数据和实际地震数据的测试处理,同时与传统的EMD处理结果相对比.结果表明,本文方法对地震随机噪声的衰减有更佳的压制效果.

     

QUATERNARY FOLDING OF THE XIHU ANTICLINE BELT ALONG FORELAND BASIN OF NORTH TIANSHAN

Tianshan is one of the longest and most active intracontinental orogenic belts in the world. Due to the collision between Indian and Eurasian plates since Cenozoic, the Tianshan has been suffering from intense compression, shortening and uplifting. With the continuous extension of deformation to the foreland direction, a series of active reverse fault fold belts have been formed. The Xihu anticline is the fourth row of active fold reverse fault zone on the leading edge of the north Tianshan foreland basin. For the north Tianshan Mountains, predecessors have carried out a lot of research on the activity of the second and third rows of the active fold-reverse faults, and achieved fruitful results. But there is no systematic study on the Quaternary activities of the Xihu anticline zone. How is the structural belt distributed in space?What are the geometric and kinematic characteristics?What are the fold types and growth mechanism?How does the deformation amount and characteristics of anticline change?In view of these problems, we chose Xihu anticline as the research object. Through the analysis of surface geology, topography and geomorphology and the interpretation of seismic reflection profile across the anticline, we studied the geometry, kinematic characteristics, fold type and growth mechanism of the structural belt, and calculated the shortening, uplift and interlayer strain of the anticline by area depth strain analysis.
In this paper, by interpreting the five seismic reflection profiles across the anticline belt, and combining the characteristics of surface geology and geomorphology, we studied the types, growth mechanism, geometry and kinematics characteristics, and deformation amount of the fold. The deformation length of Xihu anticline is more than 47km from west to east, in which the hidden length is more than 14km. The maximum deformation width of the exposed area is 8.5km. The Xihu anticline is characterized by small surface deformation, simple structural style and symmetrical occurrence. The interpretation of seismic reflection profile shows that the deep structural style of the anticline is relatively complex. In addition to the continuous development of a series of secondary faults in the interior of Xihu anticline, an anticline with small deformation amplitude(Xihubei anticline)is continuously developed in the north of Xihu anticline. The terrain high point of Xihu anticline is located about 12km west of Kuitun River. The deformation amplitude decreases rapidly to the east and decreases slowly to the west, which is consistent with the interpretation results of seismic reflection profile and the calculation results of shortening. The Xihu anticline is a detachment fold with the growth type of limb rotation. The deformation of Xihu anticline is calculated by area depth strain analysis method. The shortening of five seismic reflection sections A, B, C, D and E is(650±70) m, (1 070±70) m, (780±50) m, (200±40) m and(130±30) m, respectively. The shortening amount is the largest near the seismic reflection profile B of the anticline, and decreases gradually along the strike to the east and west ends of the anticline, with a more rapidly decrease to the east, which indicates that the topographic high point is also a structural high point. The excess area caused by the inflow of external material or outflow of internal matter is between -0.34km² to 0.56km². The average shortening of the Xihubei anticline is between(60±10) m and(130±40) m, and the excess area caused by the inflow of external material is between 0.50km² and 0.74km². The initial locations of the growth strata at the east part is about 1.9~2.0km underground, and the initial location of the growth strata at the west part is about 3.7km underground. We can see the strata overlying the Xihu anticline at 3.3km under ground, the strata above are basically not deformed, indicating that this section of the anticline is no longer active.     

倾斜航空摄影数据获取之实践研究

利用倾斜摄影测量技术进行城市三维模型数据生产,具有快速高效、模型纹理真实、数据精度高等特点,在数据生产单位得到大规模应用。本文以实际的生产项目为例阐述了倾斜航空摄影的数据获取过程。     

城市地下综合管线信息系统数据更新模式探讨

城市地下综合管线数据库是管线信息系统的重要组成部分,及时、准确、权威的综合管线数据成果是管线信息系统能够有效应用、确保城市运行安全的前提和基础.本文以芜湖市城市建设地下管线管理探索为例,参考美国811管线管理与服务模式,结合城市地下管线探测与管理相关法律法规和标准规范,从机制体制和信息技术角度阐述如何利用新建(改建、扩建)工程电子报批竣工验收归档的管线相关数据成果.通过管线数据质量检查、数据融合处理与建库、二三维一体化建模,达到及时同步更新综合管线数据库、对历史数据进行有效管理、支持管线成果服务应用、提高行业管理水平、保障城市运行安全的目的,为各类基础和综合管线系统更好地发挥其应用价值提供良好的数据服务支撑.     

中国大陆流域分区TRMM降水质量评价

根据中国境内2 257个气象站点1998-2013年逐日降水资料,结合流域分区,采用探测准确性、相关系数以及相对误差等指标,对热带降水测量（TRMM）降水精度和一致性进行系统评价。结果表明:① TRMM日降水准确性从东南沿海向西北内陆递减;② 气象站点年均降水日数显著大于TRMM年均降水日数;③ 西北片区以外气象站点降水量和TRMM降水量在月尺度和年尺度上均具有较好的相关关系;④ 各流域年均TRMM面降水量均高于气象站点面降水量,且TRMM面降水量相对误差雨季较小,枯季较大;⑤ 各流域TRMM面降水量与气象站点面降水量演变趋势基本一致,南方各流域年降水量均呈减少趋势,北方各流域年降水量均呈增加趋势,全国尺度上年降水量呈微弱的减少趋势。     

纳米材料对顶管法施工触变泥浆减阻性能影响及浓度优选研究

顶管法施工具有设备少、工序简单、工期短、造价低等优点,被广泛应用于城市涵管、管廊等工程中。触变泥浆是顶管施工中重要的润滑减阻剂,其减阻性能的好坏对顶管施工特别是长距离、大断面顶管工程的顺利进行至关重要。论文使用膨润土触变泥浆为基础泥浆,质量配比为膨润土：羧甲基纤维素钠（CMC）：无水Na₂CO₃：水=80 ： 2 ： 3 ： 920,并选择纳米ZnO、纳米SiO₂、纳米Al₂O₃ 3种纳米材料作为添加剂,通过测试泥浆密度、pH、六速黏度、滤失、泥饼黏附系数和析水率等指标的变化,确定最优纳米材料类型并优选配比浓度。结果表明：浓度为2%纳米SiO₂触变泥浆的减阻性能最好,比基浆减阻性能提升约14%。本文研究成果可为提高长距离、大断面顶管施工中触变泥浆的减阻性能提供一定借鉴,对纳米材料在触变泥浆中的应用具有一定参考作用。     

端视电感耦合等离子体发射光谱法测定土壤中有效钼

样品经草酸?草酸铵溶液(Tamm溶液)浸提,分取浸提液,蒸干灼烧破坏草酸盐,制备成硫酸介质溶液,采用端视电感耦合等离子体发射光谱法测定土壤中有效钼。方法检出限(3s)为0.013μg/g,精密度(RSD,n=12)为2.13%~6.70%。经国家一级标准物质验证,测定值与标准值吻合。     

CFG桩复合地基褥垫层三维弹塑性分析

在CFG桩复合地基中, 褥垫层的设置厚度和模量对于复合地基的承载及变形特性有较大的影响。本文建立了CFG桩复合地基的三维弹塑性数值分析模型,研究了当采用不同厚度和模量的褥垫层时,复合地基沉降、桩端沉降、褥垫层压缩量和桩土应力等参数的变化规律。结果表明复合地基沉降和褥垫层压缩量随着垫层厚度的增加而增大,而随着垫层模量的增大而减小;垫层厚度和模量的变化对于桩端沉降的影响较小,从工程角度可认为桩端沉降不随垫层厚度与垫层模量的变化而变化;桩土应力比随垫层厚度的增大而减小,随垫层模量的增大而增大。本文建立的分析模型还可进一步对CFG桩复合地基的其他参数进行相应的分析计算,分析结果可以为复合地基的设计和施工提供相应的理论依据。     

控制点影像库在遥感影像几何纠正中的应用

影像几何纠正是遥感图像处理的重要技术。为了克服现有方法在实际应用中的不足,提出利用控制点影像库进行影像自动匹配,然后进行几何变化的方式。这种方法简单有效,快速稳定,匹配得到的同名点数量足够且分布均匀,并通过引入最小二乘匹配使配准达到子像素精度,提高几何纠正的速度与可靠性。     

长江三峡地区的夷平面在宜昌地区白垩纪—第四纪沉积物中的反映

通过对湖北宜昌地区白垩纪-第四纪沉积演化的研究,发现存在3个明显的沉积旋回,每个旋回由下部颗粒粗大的砾石层和上部颗粒较细小的粉砂-泥质层组成。3个沉积旋回对应了宜昌以西三峡地区3期构造演化旋回,同时反映了三峡地区3期夷平面的存在。结合前人研究结果、古生物化石和对第四系善溪窑组的测年数据,认为3期夷平面形成时代分别为:鄂西期夷平面形成于白垩纪晚期-古近纪的始新世,山原期夷平面形成于上新世-早更新世初,云梦期夷平面形成于早更新世末-中更新世早期。