1,083 research outputs found

    Estimating Submarine Groundwater Discharge into the Jiaozhou Bay Using ~(226)Ra

    Get PDF
    海底地下水排泄(SGD)是全球水循环的一个组成部分,其输送的溶解物质不仅参与海洋的生物地球化学循环,而且影响近岸海域的生态环境。为了评估胶州湾海底地下水排泄状况,通过建立胶州湾内海水中226Ra的质量平衡模型来计算海底地下水排泄通量。胶州湾海水中226Ra的源主要有河流的输入、沉积物扩散输入和地下水的输入,海水系统在稳定状态下,这几种源应该与湾内海水和湾外海水的混合损失达到平衡。除了将地下水输入作为未知项外,对其他源和汇逐个进行量化,计算得知:2011年9—10月胶州湾的海底地下水排泄通量为7.85×10~6m~3·d~(-1);2012年4—5月胶州湾的海底地下水排泄通量为4.72×106m~3·d~(-1)。在此基础上,对地下水输入胶州湾的营养盐进行了评价。Submarine groundwater discharge( SGD) is a part of global water cycle,which delivers a large amount of solutes to the biogeochemical cycle and affects the coastal ecological environment. The ~(226)Ra mass balance model was established to estimate the submarine groundwater discharge to the Jiaozhou Bay. The ~(226)Ra sources include river transport,sediment diffusion and SGD,these sources should be in balance with the mixing loss of the bay water and open seawater when the seawater system is in the stable state. Except for the SGD was unknown item,other sources and sinks were quantified one by one. Calculated results showed that the SGD fluxes during September to October in 2011 was 7. 85 × 106m~3·d~(-1),April to May in 2012 was 4. 72 × 106m~3·d~(- 1). Based on the SGD fluxes,the SGD derived nutrient fluxes were estimated.国家自然科学基金项目(41072174)~

    饱和土动力方程全显式有限元法在OpenSees中的实现与应用

    Get PDF
    饱和土的动力响应一直是土动力学重点关注的问题,尤其是在循环荷载作用下饱和砂土容易发生孔压升高、强度降低的液化现象。同时,采用有限元法求解尺寸较大的实际饱和土场地,巨大的自由度数往往造成整体系统的计算效率极低,制约着饱和土数值方法的发展。因此,基于已提出的u-p(u为固相土骨架位移,p为孔压)饱和两相多孔介质动力方程的全显式有限元法,将其嵌入Open Sees开放性平台中,并利用软件自带的饱和多孔介质单元和本构模型,实现了高效、显式计算饱和土的动力响应。通过计算二维弹性饱和土动力响应,与Newmark法的计算结果对比,两者结果吻合较好,验证了嵌入算法的正确性。将提出方法计算非线性自由场海床土的地震响应问题,有效模拟了海床土的液化过程和失效模式以及发生的侧向变形,同时说明了提出方法在计算效率方面具有的显著优势。国家自然科学基金创新群体项目(No.51421005);国家自然科学基金面上项目(No.51578026)~

    复合地层盾构刀盘掘进速率及受力特性分析

    Get PDF
    为探究复合地层中盾构刀盘的掘进速率及受力特性,基于连续-非连续单元法(CDEM),建立盾构-岩土体这一完整系统的数值计算模型。通过在CDEM中引入简单有限体积法、虚拟质量法、单元溶蚀算法等系列算法,实现盾构刀盘掘进全过程的三维模拟。建立5种刀盘面花岗岩占比的刀盘破岩数值模型,并对不同刀盘面花岗岩占比下的刀盘进尺、掘进速率、平均转矩、平均倾覆力矩等进行详细分析。数值模拟结果表明:1)在某一特定复合地层中掘进时,随着掘进时间增加,刀盘进尺基本呈线性增大的趋势,但进尺曲线中平缓段及速升段交替循环出现; 2)刀盘面花岗岩占比由0增大至100%,掌子面处拉伸破坏单元增加,剪切破坏单元减少,且刀盘的掘进速率呈指数衰减趋势,掘进速率降低88. 7%; 3)刀盘面花岗岩占比由0增大至100%,平均转矩值逐渐增大,增大比例为117. 5%,平均倾覆力矩值则呈现先增大后减小的趋势,且在花岗岩占比为50%时最大

    A cleaner production process of tertbutyl phenol

    Get PDF
    叔丁基苯酚是非常重要的精细化工产品,主要包括对叔丁基苯酚(4-TBP)、邻叔丁基苯酚(2-TBP)及其他衍生物。其中4-TBP在树脂、荧光增白剂、抗氧剂、香料、农药及医药等方面应用极为广泛。2-TBP也广泛应用于香料、受阻酚类抗氧剂、阻燃剂、高效阻聚剂及医药等化工产品的合成。目前国内叔丁基苯酚的供给主要依靠进口,市场需求量大,产品供不应求。 我国叔丁基苯酚的生产工艺主要以硫酸催化法和树脂催化法为主,该类老工艺或者能耗物耗大、对设备腐蚀严重且存在严重的三废处理等问题,或者催化剂不稳定、难以满足工业化生产需求。与美国、日本等叔丁基苯酚的生产大国相比,我国叔丁基苯酚的生产技术水平及生产能力还有待提...Tert-butyl phenols, including 2-tert-butyl phenol (2-TBP), 4-tert-butyl phenol (4-TBP) and other derivatives, are important fine chemical products. Among them, 4-TBP is an important raw material for the preparation of phenolic resin, fluorescent whitening agents, antioxidants, perfume, pesticides, and pharmaceuticals. 2-TBP is widely used for the synthesis of fragrance, hindered phenolic antioxida...学位:工程硕士院系专业:化学化工学院_工程硕士(化学工程)学号:2062014115145

    Late Quaternary Sediment Stratigraphy and Marine Cycles in the Pingtan Island, Fujian Province

    Get PDF
    选择位于福建平潭岛北部芦洋埔海积平原的PT01钻孔,岩芯长度28.3 m,采用加速器碳同位素(AMS 14C)和光释光(OSL)测年建立地层年代框架,认为晚更新世富含有孔虫等海相生物化石的地层应归属于MIS 5高海面期,即MIS 5e的潮下带滨海相沉积。结合岩性特征、古生物化石、沉积物色度、粒度分析及其参数等指标,进行了沉积单元的划分,重建了MIS 6末期以来的沉积相变化过程,揭示出MIS 5期间的多次海平面波动变化,即MIS 5高海面期沉积环境仍存在滨海、潮坪、潟湖、风成砂等沉积相之间的转换,并可能存在短暂的陆相或风化过程。而该区整个末次冰期的沉积缺失或较薄,上部全新世沉积也不发育,厚度仅为3.79 m,以沼泽相―风成砂相为主。A 28.3 m long core, PT01, from the Pingtan Island, Southeast China, is selected to be studied. Radiocarbon dating(AMS 14C) and optical stimulated luminescene(OSL) are used for establishing chronology. Combining age-dating results with marine microfossil and color index, we classify the Late Quaternary sediment stratigraphy in the coastal region of Fujian Province. It is suggested that the late Pleistocene marine deposit, dated back to 124 ka, and abundant marine microfossil(e.g. foraminifer and ostracods), would belong to the Marine Isotope Stages 5(MIS 5). Moreover, the late Quaternary sediment could be divided into three units based on the analysis of lithology, microfossil, grain size and color index. Our results reveal that the sediment environment during the MIS 5 was significantly controlled by global sea level change which varied among coast, tidal flat, lagoon, and eolian sand, and probably there existed weathering process. A hiatus during the last glacial(MIS 2-4) was attributed to low relative sea level. And the Holocene deposit, as thick as 3.79 m, developed poorly and was mainly comprised of swamp facies and eolian dune.国家自然科学基金(41230101、41072128

    鄂尔多斯盆地姬塬地区长6 储层矿物含量与孔隙度的线性关系

    Get PDF
    矿物含量是影响储层物性的重要因素之一。为了较全面地分析不同类型矿物含量对储层孔隙度的影响,以鄂尔多斯盆地姬塬地区长6 砂岩储层为例,探索性地运用多元逐步线性回归法分析了石英含量(x1)、长石含量(x2)、岩屑含量(x3)、绿泥石含量(x4)、伊利石含量(x5)、高岭石含量(x6)、硅质含量(x7)以及铁方解石含量(x8)与孔隙度(y)的关系,建立了矿物含量(xi)与孔隙度(y)之间的回归模型:y = 21.131-0.086 x2-0.113 x3-0.554 x4-0.370 x5-0.199 x6-0.659 x7-0.465 x8。结果表明:绿泥石、伊利石、硅质含量及铁方解石含量对长6 储层孔隙度的影响较大,而长石、岩屑、高岭石含量对孔隙度影响较小,石英含量对孔隙度几乎没有影响。对多元回归模型的检验发现,实测孔隙度与模型孔隙度之间具有较好的拟合度,多元逐步回归分析法在多因素影响储层物性问题研究中具有一定的优越性,相比单因素分析法更能揭示出影响储层物性的本质

    Taiwan as an example for “Source to Sink” processes of particulate organic matter in high mountainous river and surrounding marginal seas

    Get PDF
    陆海交互界面“源到汇”沉积体系由高山环境延伸,横跨大陆边缘,最后汇入深海,是侵蚀和沉积过程发生的主要位置,构成地球沉积循环的主要组成部分,同时,也是连接地球系统长时间尺度碳循环的枢纽。在轨道时间尺度上,大气二氧化碳的含量主要取决于化石碳的氧化以及光合作用所固定碳的埋藏这二者之间的平衡。而陆海交互界面是这两个过程发生的主要场所,因此理清陆海交互界面碳的迁移转化过程对定量全球碳收支至关重要。高山岛屿(high-standingislands)的河流流域面积占地球面积不到3%,每年向海洋输入的有机碳却占全球入海通量的17-35%,是研究碳源汇过程理想的天然实验场。因此本文以台湾高山流域的土壤、水库悬...The sedimentary “source to sink” system in land-to-ocean boundary is extended from the high mountain, across the continental margin, and eventually dumps into the deep sea. It is the primary locations for the erosion and deposition processes take place, which constitutes the sedimentary cycle of the earth and is also connected to the earth system for a long-term carbon cycle. At geological time sc...学位:理学博士院系专业:海洋与地球学院_海洋化学学号:2232013015377

    Research on the Penetration of Spudcan Foundation for Mobile Jack-Up Platform

    Get PDF
    [Introduction] The spudcan foundation is the key structure of the mobile jack-up platform, which displaces surrounding soil during its penetrating installation. In order to ensure the safety in the application of mobile jack-up platform to the offshore wind power installation works, it is particularly important to research the evolution of surrounding soil flow mechanism during spudcan penetration, and to evaluate the penetration resistance of spudcan reliably. [Method] The coupling Euler-Lagrange (CEL) method was used in this research to simualte the process of spudcan penetration under several typical seabed geological conditions (homogeneous and heterogeneous clay, sand, "clay-sand-clay" and "clay (hard)-sand (soft) and clay (hard)"), and to analyze the differences of penetration mechanisms. [Result] The simulation results show that in the process of spudcan penetration, the soil flow mechanism and penetration resistance of spudcan are closely related to the strength characteristics of seabed soil, while the friction coefficient of the interface between spudcan and seabed soil has little effect on the penetration mechanism and resistance. [Conclusion] From comparision with the results calculated in accordance current design specifications, the method combining large deformation finite element analysis and industry code design should be recommended to be applied in engineering design practice, as to provide a better basis for the assessment of punch-through risk and the prediction of penetrating depth in the process of spudcan penetration
    corecore