Amplitude variation characteristics of active source airgun signals at Qilian Mountain

In this study, Qilian Mountain active source airgun signals recorded at 79 stations were obtained after stacking waveforms from July 2015 to December 2016. Based on analysis of the amplitude variation characteristics of the airgun signals, the following conclusions were drawn:along the NW-SE fault distribution direction of the Qilian Mountain area, the decrease in amplitude of airgun signals was relatively slow in relation to the epicentral distance, while the decrease in amplitude in the direction perpendicular to the fault was relatively fast. This difference may be related to the energy loss of seismic waves reflecting and scattering by the regional faults mainly distributed along the NW-SE direction, which are caused by tectonic compression of the Qinghai-Tibet and Alxa blocks.     

海南建省以来区域经济发展的空间分异研究

海南建省以来,海南经济快速发展.在分析海南建省以来区域经济发展变化的基础上,对建省初期和当前县(市)域经济发展水平进行了数量分析和对比研究.结果表明,海南建省以来区域经济发展的不均衡性进一步增强,海口、三亚、琼海、东方、儋州等5市已发展成为海南经济的增长极,县(市)经济的发展水平与优势产业发展密切相关.     

有机污染物在不同沿海沉积环境中积累的差异性

以浙江沿海水域为研究区域,在系统地测定水体与沉积物中有机污染物种类的基础上,研究了表层沉积物中有机污染物的积累与沉积环境、沉积物矿物组成和排放环境因素之间的相互关系.结果显示,沿海水体和表层沉积物中主要存在的有机污染物有石油烷烃类化合物、邻苯二甲酸酯化合物、有机硅氧链类化合物、氯代苯酚类、苯醚类和胺类化合物等6大类,它们在表层沉积物中的积累强度呈现出河口大于沿岸大于强潮汐河沉积环境的趋势,但在相同沉积环境的沉积物中有机污染物的积累强度存在一定的差异,这说明有机污染物在沿海沉积物中的积累除与沉积环境有关外,还与区域有机污染物的排放特点有关.     

大跨斜拉桥悬臂端钢箱梁上监测点高程测量新方法

在斜拉桥的主梁施工中,需要高精度测量悬臂端钢箱梁的高程。随着悬臂的增长,桥面的晃动越来越大,水准仪读数的难度也越来越大,甚至读不出数据;同时由于梁面上施工设备的影响,测量的难度很大,时间也很长。本文提出采用Leica TCA2003全站仪测量高差和水准仪测量工作基点高程相结合的方法,测量钢箱梁上监测点的高程,通过理论分析和对比实验证明了该方法的可行性。     

双频相位求差法与多普勒法探测与修复周跳的比较

介绍产生周跳和常用的探测与修复周跳方法,并通过用双频相位求差法和多普勒方法对周跳进行探测和修复,算例结果表明两种方法均能准确地锁定发生小周跳的历元,且能高效地修复观测值。两种方法执行效率高,实用性强,适合RTK等动态导航定位的应用。     

基于差分变换和均值变换的线状要素的无损压缩

线状要素是地理信息系统、地形环境仿真的基础数据,其压缩优化的研究具有重要的现实意义。根据线状要素存储的结构特点和无损压缩算法的编码特点,利用差分变换和均值变换对线状要素的结构进行优化、调整,精简线状要素的存储空间,减少数据存储冗余,集中数据能量,然后运用通用LZW压缩算法对数据进行二次压缩,达到了较高的压缩率。     

Improved earthquake locations in the Koyna-Warna seismic zone

In estimating the likelihood of an earthquake hazard for a seismically active region, information on the geometry of the potential source is important in quantifying the seismic hazard. The damage from an earthquake varies spatially and is governed by the fault geometry and lithology. As earthquake damage is amplified by guided seismic waves along fault zones, it is important to delineate the disposition of the fault zones by precisely determined hypocentral parameters. We used the double difference (DD) algorithm to relocate earthquakes in the Koyna-Warna seismic zone (KWSZ) region, with the P- and S-wave catalog data from relative arrival time pairs constituting the input. A significant improvement in the hypocentral estimates was achieved, with the epicentral errors <30 m and focal depth errors <75 m i.e. errors have been significantly reduced by an order of magnitude from the parameters determined by HYPO71. The earthquake activity defines three different fault segments. The seismogenic volume is shallower in the south by 3 km, with seismicity in the north extending to a depth of 11 km while in the south the deepest seismicity observed is at a depth of 8 km. By resolving the structure of seismicity in greater detail, we address the salient issues related to the seismotectonics of this region.     

河南县域经济实力评价及空间差异分析

采用因子分析和GIS技术,对河南县域经济体的经济实力进行综合评价和空间差异分析.结果表明:(1)河南县域经济空间差异由东西差异转变为由西北向东南的梯次差异,县域经济发展在空间上呈现出集中、差异扩大趋势.(2)山区县经济实力高于平原县,交通条件较好的郑州至三门峡陇海铁路沿线和郑州市所辖县域经济实力较高.(3)县域经济的发展在很大程度上还处于依赖区内初级生产要素的低级发展阶段,高等生产要素发育较少,对经济的推动作用还没有显现出来.     

安徽省人居环境空间差异分析

当今世界,随着城市化、工业化的高度发展,人们的生活水平不断提高,但一系列环境问题也随之出现并严重威胁着人类的健康和生存.人居环境的建设逐步成为学术界关注的焦点与重点领域之一.笔者选取安徽省13个城市,利用主成分分析和聚类分析的方法对安徽省的人居环境进行评价,建立了人居环境综合评价指标体系.经过分析,将13个城市分为4个类型,最后根据问题提出对策.