Effect of NAPL exposure on the wettability and two‐phase flow in a single rock fracture

Surface‐wetting properties are an important cause of changing the groundwater and two‐phase fluid flows. Various factors affecting the surface wettability were investigated in a parallel‐walled glass fracture with non‐aqueous phase liquid (NAPL) (gasoline, diesel, trichloroethylene, and creosote) wetted surfaces. First, the effect of the duration of NAPL exposure on wettability change was considered at pre‐wet fracture surfaces using the various NAPL species, and the result showed that the surface became hydrophobic after the exposure time of NAPL exceeded 2000 min. Second, the initial wetting state of the surface affected the timing when the wettability change begins as well as the extent of the wettability change in an NAPL‐wetted rock fractures. Under the dry condition, the wettability change was completed within a very short time of exposure to NAPL (~5 min), and then it finally reached the intermediate and weakly NAPL wetting (contact angle of 118°). Under the pre‐wet condition, a relatively long time of exposure (~5000 min) was needed to observe the obvious change of the surface wettability, which was changed up to strongly NAPL wetting (contact angle of 142°). Third, the wettability changed by NAPL exposure was stable and maintained for a long time, regardless of water flushing rate and temperature. Finally, the wettability change by the exposure of NAPL on parallel fracture surfaces was evaluated at various groundwater flow velocities. Result showed that groundwater flow velocity has an important impact upon measured contact angle. Although fracture surfaces were exposed to NAPL at the low groundwater flow velocity, the wettability was not changed from hydrophilic to hydrophobic when the contact time between NAPL and mineral surfaces was not sufficient owing to the pulse‐type movement of NAPL. This implies that the variation of exposure pattern due to groundwater flow on the wettability change can be an important factor affecting the wettability change of fracture surface and migration behaviour at natural fractured rock aquifers in case of NAPL spill. Copyright © 2015 John Wiley & Sons, Ltd.     

同步激光测高数据的垂线偏差解算与分析

针对传统的垂线偏差计算过程中东西分量与南北分量差异过大的问题,提出了利用新型ICESat-2海面高数据获取高精度东西分量的方法,选定南中国海域(0°～23°N、103°～120°E)作为试验区域,基于ICESat-2 ATL12海表面高度数据产品进行垂线偏差解算.与此同时,采用XGM2019e_ 2159模型检核,对比同时间序列长度的Jason-2解算结果,分析了ICESat-2多波束同步观测模式的垂线偏差解算优势.数值试验表明:ICESat-2获取的海面高观测值精度优于传统雷达测高模式,计算的沿轨垂线偏差精度与Ku波段测高模式相当.ICESat-2中间束强波束的垂线偏差解算精度优于两侧强波束,并且多波束组模式首次提供了跨轨方向的同步观测数据,解算的跨轨垂线偏差精度可靠,可以提升垂线偏差东西向分量的确定精度.     

数字地球下的地震灾情快速评估系统设计与实现

地震快速评估可以在地震发生后一段时间内的"黑箱期"快速获得地震灾情信息.设计并实现一套基于数字地球科学平台的地震应急灾害快速评估系统.该系统采用插件化开发模式,在三维场景可视化及交互式图形界面技术的基础上,引入空间分析、灾情简报快速产出及辅助决策等功能实现系统自动化运行,并在结果产出速度上满足地震应急的时效性要求.通过系统总体架构设计、系统功能设计以及地震灾情快速评估业务流程设计等方面阐述了地震灾情快速评估系统的实现,为灾情评估三维可视化提供了支持,以更好地服务于地震灾情损失评估.     

岷江双线特大桥高边坡稳定性研究

成兰铁路岷江双线特大桥高边坡位于岷江地震带,该区域属于高烈度地震强震频发区,降雨量大且集中,不良地质分布广,在复杂环境因素的影响下,极其容易引起边坡滑坡。在研究现场工程地质情况的基础上,利用FLAC3D有限差分软件,建立三维边坡模型,进行天然、降雨、地震及降雨-地震耦合工况下的稳定性分析。研究结果表明,天然工况下安全系数为1.318,边坡处于稳定状态;降雨工况下,随降雨量的增加,雨水入渗和加载作用增强,位移高值区逐步扩大并逐渐向坡脚延伸,25 mm/d、35 mm/d及45 mm/d降雨条件下的安全系数分别为1.001、0.932、0.912;地震工况下边坡不稳定,坡腰中上部位移与加速度最大,为易滑坡区域;降雨-地震耦合工况下,坡腰中上部极其不稳定,且随降雨量增加,滑体位移及加速度均增大。     

Research on Biofacies their Provincialization of Middle Permian-MiddleTriassic in the western Sichuan Basin

The research area is located in the western part of Sichuan basin as a Yangtze ecotope of Cathaysian Tethyan area. It is dominated by benthic fauna, including brachiopods, Fusulinids, corals, bivalves, foraminifers, ammonites, bryozoans, Crinoids and pleopods are less common with traces of trilobites, stromatoporas, nautilus and sporopollens seen in one or two areas,which are obviously controlled by sedimentary environments in accordance with sedimentary facies. On the basis of division and research of biological communities and according to the combination of communities with sedimentary characteristics, six kinds of biofacies have been recognized and described in the study area,i.e. benthic biofacies of restricted platform, benthic biofacies of open platform, benthic biofacies of inner gentle slope, benthic biofacies of outer gentle slope, benthic biofacies of shelf slope and swimming biofacies of deep-water basin. Based on the study of middle Permian to middle Triassic biofacies,biofacies pattern are established, category, ecotype, typical community, sedimentary facies and oil bearing of each biofacies are elucidated in this paper. According to the association law of biofacies in time and space, the ahthors think that there are three biofacies provinces in the study area, i.e., platform biofacies province, slope biofacies province and basin biofacies province.The distribution characteristics of bioface types indicates that the platform-type and ramp-type biofacies are mainly distributed in the subject of the study area. It indicates that their distribution are mainly controlled by Yangtze platform. But the bioface of deep water basin type biofacies and basin biofacies province are mainly distributed at the edge of study area, indicating that they are mainly controlled by the Longmen trough. The study of biofacies and their provincialization of Middle Permain-Middle Triassic in the Western Sichuan Basin is a reference for the reconstruction of paleogeography and paleo-plate.Therefore, the research is meaningful for the analysis of paleogeography, tectonics and their evoulution of the Sichuan Basin.     

基于模糊数学评价法优化凡纳滨对虾真空微波干燥工艺

【目的】探求真空微波干燥凡纳滨对虾的最佳工艺条件,以期为开发凡纳滨对虾即食食品提供技术参考。【方法】以新鲜凡纳滨对虾为原料,模糊数学感官评分为主要考察指标,在单因素试验基础上,选择载装量A、功率B、真空度C为自变量,利用响应面法和模糊数学评价法对真空微波干燥工艺进行优化。【结果】以感官评定为基础对真空微波干燥凡纳滨对虾的品质进行权重分析,得到权重集K=(色泽0.335,滋味0.305,香气0.215,组织质地0.145)。建立二次多项回归方程:Y=84.588+1.084A+1.409B+1.700C-7.353A²-8.793B²-13.860C²,显示载装量A、功率B、真空度C对感官评分有极显著影响(P<0.01)。通过响应面分析,得到真空微波干燥凡纳滨对虾的最佳工艺条件:载装量75 g,加热功率400 W,真空度0.08 MPa。在此条件下,真空微波干燥凡纳滨对虾品质良好,感官评分为(85.6±0.07)分,与预测值85.92分误差较小。【结论】响应面法优化凡纳滨对虾真空微波干燥工艺具有操作简单、优化条件精确、结果显示直观等优点;建立的回归方程能反映装载量等三个因素对指标的影响规律,并可进行实际预测。     

地脉动测试及其在场地评价中的应用

介绍了地脉动的原理、测试方法及其影响因素,通过工程实例,阐述了场地卓越周期的测定及其在场地及场地土判定与评价中的应用,分析了不同场地条件对地脉动频谱特性的影响.结果表明通过地脉动测试确定场地卓越周期的效果较为理想,其在场地及场地土判定与评价中的结果与利用剪切波速和覆盖层厚度划分结果基本一致;场地岩土层结构直接影响地脉动的频谱特性,二者的变化相对应.     

湖泊沉积物纤维素氧同位素研究进展

纤维素作为湖泊沉积物有机质的重要组成部分,其氧同位素组成已逐渐应用在古气候、古环境重建中。本文综述了湖泊沉积物纤维素氧同位素在古气候研究中的进展,包括纤维素的实验提取方法、纤维素及其寄宿水体之间的氧同位素分馏系数,以及纤维素氧碳同位素在定量古气候参数方面的应用,并展望了未来的研究趋势。研究表明,纤维素结合碳酸盐氧同位素组成可能是一种潜在的定量古温度指示剂,可能在未来的湖泊沉积中发挥极大作用。因此,今后的有关研究可能集中在定量古气候参数上的应用。     

山东省春季马铃薯播种至出苗期水热特征分析

基于山东省1980—2020年117个气象台站的地面观测资料,依据春季马铃薯播期,通过积温法推算出苗期,分析山东省春季马铃薯播种至出苗期水分条件和热量条件的变化特征。结果表明：1980—2020年山东省春季马铃薯播种至出苗期平均日数为39.5 d,10 a倾向率为-1.8 d;降水量平均为16.5 mm,10 a倾向率为-3.1 mm;相对湿润度指数平均值为-0.48,10 a倾向率为-0.09;平均气温为8.9 ℃,10 a倾向率为0.6 ℃;温度适宜度平均为0.54,10 a倾向率为0.07。综上可知,山东省春季马铃薯播种至出苗阶段水分条件呈现减少的趋势,应增加田间灌水;热量条件呈现增加的趋势,有利于增加种植面积。     

Biodiversity and distribution of benthic dinoflagellates in tropical Zhongsha Islands,South China Sea

Journal of Oceanology and Limnology - Benthic dinoflagellates have attracted increasing attention in recent years because of their toxicity and ability to form extensive harmful algal blooms....