The influence of the corrosion product layer generated on the high strength low-alloy steels welded by underwater wet welding with stainless steel electrodes in seawater

The high strength low-alloy steels are welded by underwater wet welding with stainless steel electrodes. The micro-structural and electrochemical corrosion study of base metal (BM), weld zone (WZ) and heat affected zone (HAZ) are carried out to understand the influence of the corrosion product layer generated on the high strength low-alloy steels welded by underwater wet welding with stainless steel electrodes, methods used including, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and scanning electron microscope (SEM). The results indicate that the WZ acts as a cathode and there is no corrosion product on it throughout the immersion period in seawater. The HAZ and BM acts as anodes. The corrosion rates of the HAZ and BM change with the immersion time increasing. In the initial immersion period, the HAZ has the highest corrosion rate because it has a coarse tempered martensite structure and the BM exhibites a microstructure with very fine grains of ferrite and pearlite. After a period of immersion, the BM has the highest corrosion rate. The reason is that the corrosion product layer on the HAZ is dense and has a better protective property while that on the BM is loose and can not inhibit the diffusion of oxygen.     

Influence of climate variability and human activities on stream flow variation in the past 50 years in Taoer River,Northeast China

Taoer River Basin, which is located in the west of Northeast China, is an agropastoral ecotone. In recent years, the hydrological cycle and water resources have changed significantly with the deterioration of the environment. Many water problems such as river blanking, wetland shrinking and salinization have occurred in this region. All of these phenomena were directly caused by changes in stream flow under climate variability and human activities. In light of the situation, the impact of climate variability and human activities on stream flow should be identified immediately to identify the primary driving factors of basin hydrological processes. To achieve this, statistical tests were applied to identify trends in variation and catastrophe points in mean annual stream flow from 1961 to 2011. A runoff sensitive coefficients method and a SIMHYD model were applied to assess the impacts of stream flow variation. The following conclusions were found: 1) The years 1985 and 2000 were confirmed to be catastrophe points in the stream flow series. Thus, the study period could be divided into three periods, from 1961 to 1985 (Period I), 1986 to 2000 (Period II) and 2001 to 2011 (Period III). 2) Mean annual observed stream flow was 31.54 mm in Period I, then increased to 65.60 mm in Period II and decreased to 2.92 mm in Period III. 3) Using runoff sensitive coefficients, the contribution of climate variability was 41.93% and 43.14% of the increase in stream flow during Periods II and III, suggesting that the contribution of human activities to the increase was 58.07% and 56.86%, respectively. 4) Climate variability accounted for 42.57% and 44.30% of the decrease in stream flow, while human activities accounted for 57.43% and 55.70% of the decrease, according to the SIMHYD model. 5) In comparison of these two methods, the primary driving factors of stream flow variation could be considered to be human activities, which contributed about 15% more than climate variability. It is hoped that these conclusions will benefit future regional planning and sustainable development.     

地质年代第四纪界线被重新划定

据《第四纪科学杂志》（Journalof Quaternary Science）报道,在经历了数十年的争论和为期4年的研究之后,一个由地球科学家组成的国际权威机构最终正式认定将史前第四纪的起始界线前移80万年。这一决议是由国际地层委员会（ICS）做出的,该委员会正式宣布了第四纪的起始时间,     

谱分解在含气检测中的应用

由于含气砂岩的非均质性,地震波在经过含气砂岩时高频能量衰减强,低频能量衰减弱.从而在储层的下方可能出现低频强振幅的阴影区.因此,可用时频分析直接对储层的含气性进行检测.时频连续小波变换是对连续小波变换方法的改进.变换的结果是时频域,不需要尺度-频率的转换;且时频分辨率高.本文将它用于储层含气性检测.     

Simulations of Vertical and Horizontal Displacement Fields in the 2008 Wenchuan Earthquake

By using the Yoshimitsu Okada and Steketee fault dislocation model,we calculated the vertical and horizontal displacements along the Yingxiu-Beichuan inverse fault and Guanxian-Anxian inverse fault along which the Wenchuan MS8. 0 earthquake occurred in 2008. Compared to the achievements of field surveying along the surface rupture zone,we found that our computational results are comparable to the real displacement variation trend. Furthermore,the computational results indicated that the surface displacement...     

基于时间序列遥感数据的西藏山南地区植被覆盖变化特征分析

基于2002-2013年长时间序列MODIS-NDVI遥感数据,采用Mann-Kendall检验、多元回归分析、GIS空间分析等方法,分析了西藏山南地区植被覆盖的时空变化特征,并结合地表温度和降雨量数据,采用植被-气候时空关系模型,定量分析了气候变化和人类活动对植被覆盖变化的相对贡献率。结果表明:(1)2002-2013年山南地区年均植被覆盖度在60.16%～63.26%波动,山南地区的高、中高、中等、中低、低植被覆盖度区域占比分别为40.96%、14.07%、14.93%、14.16%、15.88%。(2)近12年来,西藏山南地区植被覆盖的变化趋势大体处于平稳状态,植被覆盖度下降区域占总面积的11.8%,植被覆盖度上升区域占3.18%。(3)气候变化是影响植被生长的决定性因素,但人类活动可在短期内加快植被变化速率。在植被覆盖度下降区域,气候变化和人类活动的贡献分别为93.75%和6.25%;在植被覆盖度上升区域,气候变化和人类活动的贡献分别为76.57%和23.43%。     

Establishing a Clean‐quality Indicator System for Evaluating Reclaimed Land in the Antaibao Opencast Mine Area,China

This article discusses the existing problems associated with reclaimed land in the area of the Antaibao Opencast Coal Mine, which is located in the semi‐arid region of northwest China. The following eight indicators of the suitability of the reclaimed land were developed based on the theory of soil genesis and landscape ecology: the thickness of the effective soil layer, composition of the soil surface, vegetation index, types of covering vegetation, slope of the terrain, time of reclamation, area of the evaluation unit, and the shape index of the evaluation unit. The suitability evaluation indexes of the reclaimed land were determined using the 3S technology and fuzzy evaluation methods, which revealed that the suitability of the reclaimed land in the study area could be divided into six grades and two categories, land suitable for farming, and land suitable for trees or grass. The suitability evaluation indicators and evaluation methods developed to evaluate reclaimed land in this study will be beneficial to the large‐scale rapid monitoring and the effective management of reclaimed land in the opencast mine area.     

沉积盆地火山岩油气生储系统分析：以新疆准噶尔盆地乌夏地区早二叠世风城组为例

通过对乌夏地区早二叠世风城组油气生储特征研究,认为该区的火山作用不仅能在近火山口相的流纹质弱熔结角砾凝灰岩中,形成以裂缝气孔为主要组合的油气储集体,而且能使远火山口相白云质凝灰岩和凝灰质白云岩,在有机质丰富的条件下,共同发育为烃原岩;而这种烃源岩由于裂缝系统发育不但构成了源岩型的自生自储的油气藏,而且在横向上还可与同层异相的裂缝气孔型储层构成自生自储油气藏,形成一套一源两相的生储系统（其中的源、藏共一系统勘探意义重要）。应用地化生标、岩石类型和自生矿物等相关资料,对富含火山物质的有机相、火山岩储集类型和储集性能进行了对比和论证。同时,根据大型火山岩油气藏多与近距离的烃源岩关系密切：近源运聚或可自生自储成藏等特点提出：从不同沉积盆地和不同火山机构,总结火山岩油气生储系统分布规律是指导火山岩油气勘探的有利途径。     

青海省石炭纪-三叠纪岩相古地理

青海省位于青藏高原北部,由于特殊的大地构造位置,岩相古地理比较复杂,因此相对中国其他省份来说,岩相古地理研究程度较低,这在一定程度上制约了资源勘查工作。作者以近年来青藏高原地质工作获得的大量最新区域地质、煤炭勘查及石油地质资料与研究成果为基础,通过实地测量和收集青海省所有含煤地层剖面,首次编制了青海省石炭纪、二叠纪、三叠纪岩相古地理图,探讨了石炭纪、二叠纪、三叠纪煤炭资源沉积环境。石炭纪青海省北部为柴达木古陆及祁连古陆,自北而南有宗务隆海槽、祁漫塔格海槽、阿尼玛卿海槽及金沙江海槽。二叠纪至三叠纪,阿尼玛卿有限洋盆、西金乌兰有限洋盆及金沙江有限洋盆形成。该项工作为进一步编制青海省主要成煤期世一级岩相古地理图奠定了基础,对于青海省主要成煤区煤炭成矿预测及靶区优选目标的实现具有重要的现实意义。