Control of the stress field on shallow seafloor hydrothermal paths: A case study of the TAG hydrothermal field     

Mingxu Wang  Chunhui Tao  Chao Lei  Hanchuang Wang  Ming Chen 《海洋学报(英文版)》2022,41(9):117-126

The stress state and rock mechanical properties govern the growth of faults and fractures, which constitute shallow hydrothermal pathways and control the distribution of seafloor massive sulfide (SMS) mounds in the seafloor hydrothermal field. The stress field has an important influence on the formation and persistence of hydrothermal pathways. Based on multibeam bathymetric data from the Trans-Atlantic Geotraverse (TAG) field, we establish two three-dimensional geological models with different scales to simulate the stress field, which investigate the characteristics of hydrothermal pathways and associated SMS mounds. The simulation results show that oblique faults and fissures form in the tensile stress zone and that mounds, including active and inactive hydrothermal mounds form in the compressive stress zone. Fault activity, which is related to the stress field, affects the opening and closing of hydrothermal channels and changes the permeability structure of subseafloor wall rock. Therefore, the stress field controls the development and persistence of shallow hydrothermal pathways. The features of shallow hydrothermal pathways in the stress field can provide geomechanical information that is useful for identifying favorable zone for SMS deposit formation.  相似文献   

Crustal structure and variation along the southern part of the Kyushu-Palau Ridge     

Xiaodong Wei  Weiwei Ding  Aiguo Ruan  Jie Zhang  Xiongwei Niu  Jiabiao Li  Yong Tang 《海洋学报(英文版)》2022,41(1):50-57

As an interoceanic arc, the Kyushu-Palau Ridge（KPR） is an exceptional place to study the subduction process and related magmatism through its interior velocity structure. However, the crustal structure and its nature of the KPR,especially the southern part with limited seismic data, are still in mystery. In order to unveil the crustal structure of the southern part of the KPR, this study uses deep reflection/refraction seismic data recorded by 24 ocean bottom seismometers to reconstruct a detail...  相似文献   

Tropical cyclone genesis over the western North Pacific simulated by Coupled Model Intercomparison Project Phase 6 models     

Cong Gao  Lei Zhou 《海洋学报(英文版)》2022,41(5):64-77

Threatening millions of people and causing billions of dollars in losses, tropical cyclones(TCs) are among the most severe natural hazards in the world, especially over the western North Pacific. However, the response of TCs to a warming or changing climate has been the subject of considerable research, often with conflicting results. In this study, the abilities of Coupled Model Intercomparison Project(CMIP) Phase 6(CMIP6) models to simulate TC genesis are assessed through historical simulation...  相似文献   

Determination of Fe,Ni, Cu,Zn, Cd and Pb in seawater by isotope dilution automatic solid-phase extraction—ICP-MS     

Yuncong Ge  Ruifeng Zhang  Ziyuan Jiang  Zhan Shen  Maojun Yan 《海洋学报(英文版)》2022,41(8):129-136

A thorough understanding of the biogeochemical cycling of trace metals in the ocean is crucial because of the important role these elements play in regulating metabolism in marine biotas and thus, the climate. However, a precise and accurate analysis of trace metals in seawater is difficult because they are present at extremely low concentrations in a high salt matrix. In this study, we report an analytical method for the preconcentration and separation of six trace metals, Fe, Ni, Cu, Zn, Cd and Pb, in seawater using a seaFAST automatic solid-phase extraction device, analysis by a triple quadrupole collision/reaction technique with inductively coupled plasma mass spectrometry (ICP-MS), and quantification by the isotope dilution technique. A small volume (10 mL) of seawater sample was mixed with a multi-element isotope spike and subjected to seaFAST procedures. The preconcentrate solution was then analyzed using the optimized collision/reaction cell mode of ICP-MS, with NH₃ gas for Fe and Cd with a flow rate of 0.22 mL/min and He for Ni, Cu, Zn and Pb with a flow rate of 4.0 mL/min. The procedure blanks were 130 pmol/L, 3.0 pmol/L, 6.8 pmol/L, 37 pmol/L, 0.29 pmol/L and 0.42 pmol/L, for Fe, Ni, Cu, Zn, Cd and Pb, respectively. The method was validated using five reference materials (SLRs-6, SLEW-3, CASS-6, NASS-7 and GEOTRACE-GSC), and our results were consistent with the consensus values. The method was further validated by measuring full-water-column seawater samples from the subtropical Northwest Pacific Ocean, and our results demonstrated good oceanic consistency.  相似文献   

多光谱遥感影像的光谱规则分类算法修正及海岛、海岸带应用          下载免费PDF全文

丁凌  陈建裕  朱乾坤  陈宁华 《海洋学研究》2022,40(4):38-51

在光谱规则分类算法(Spectral Rule-based Classifier, SRC)基础上考虑大气校正对遥感影像光谱反射率的影响,提出了一种改进光谱规则的分类算法(Modified Spectral Rule-based Classifier, MSRC),从地物光谱响应曲线和光谱指数两个方面来修正光谱规则集,通过规则细化和补充、阈值改正优化光谱类别。以珠江三角洲海岛(佳蓬、淇澳)和海岸带(荃湾、惠东)的Landsat 8影像作为实验数据,对比了大气校正前后波段反射率和地物光谱响应曲线,分析了改进后MSRC算法的地物分类结果和精度,并与原SRC算法、最小距离分类(MDC)算法、最大似然分类(MLC)算法、支持向量机分类(SVM)算法、神经网络分类(NNC)算法以及基于光谱指数的算法等多种地物分类算法进行比较。结果表明,4组实验数据的MSRC算法分类结果总体精度分别为87.66%、82.38%、77.67%和80.05%,高于SRC、MDC、MLC和基于光谱指数的分类算法,在无需人工标注训练数据集的前提下接近SVM和NNC算法的分类精度。MSRC算法适用于海岛和海岸带的Landsat 8多光谱遥感影像。  相似文献   

基于无网格MPS方法数值分析方舱破舱进水问题     

卢泽宇  万德成 《海洋工程》2022,40(5):68-77

采用移动粒子半隐式法(moving particle semi-implicit,简称MPS)对自由漂浮二维方舱的破舱瞬时进水过程进行数值模拟。首先,采用基于GPU平台自主开发的MPS软件模拟破舱进水问题,并与其他方法得到的数值模拟结果进行对比验证。然后,对该二维方舱的各种模型进行了数值模拟,其中开孔位于不同位置以表示舷侧不同高度下的损坏。此外,还研究了不同类型的挡板对破舱进水后方舱稳定性的影响。结果表明损坏的孔洞和内部挡板会影响损坏舱段的运动特性,开孔距静水面的距离越大引起舱段的横摇等运动幅度越大,垂直挡板比水平挡板对舱内洪水的影响更大。  相似文献   

考虑自由面反射作用的圆柱流噪声计算     

袁常乐  赵伟文  万德成 《海洋工程》2022,40(4):129-136

对于现代舰船而言噪声是其关键性能之一,目前水下航行体的流激噪声预测方法已经较为成熟,但是水面舰船的水动力噪声研究起步较晚,还没有形成系统的预报方法和控制手段。使用开源CFD工具包OpenFOAM求解器,流场通过大涡模拟方法求解,自由液面则依靠VOF方法捕捉,通过Curle方程预测远场噪声,基于镜像法考虑自由面的反射作用,数值模拟近自由面圆柱周围的声场分布。开展了Re=3 900下距离自由液面不同高度的圆柱辐射噪声求解,主要结合流场分析自由面对声场的扰动作用和不同深度对水下几何体流噪声的影响。初步考虑了自由液面波形对辐射噪声的反射作用,为后续预测水面舰船的水动力噪声特性提供依据,自由面对辐射噪声的阻抗等作用还需进一步研究。  相似文献   

基于桁架模型和多孔介质模型的柔性网衣和周围流场单向耦合方法研究     

徐子鸣  林志良  谢彬 《海洋工程》2022,40(6):51-61

柔性网衣作为渔业养殖的重要组成部分,其水动力的计算分析对网箱的安全使用至关重要。基于桁架模型和多孔介质模型对柔性网衣和流场单向耦合计算的数值模拟方法进行了研究。通过code_aster软件基于桁架模型计算出网衣变形后节点坐标和网衣受力,然后将节点坐标导入OpenFOAM识别出网衣变形后的多孔介质区域,并基于多孔介质模型模拟水流作用下网衣周围的流场和计算网衣的受力。为了验证模型的正确性,将不同工况对圆形网衣的数值模拟结果与物理试验数据进行比较,包括code_aster中计算的网衣变形形状、OpenFOAM模拟的网衣周围流场以及在code_aster和OpenFOAM中计算的网衣受力。计算结果表明,圆形网衣在单纯来流下变形明显,与试验结果保持一致,证明了网衣变形和水动力单向耦合方法的准确性。  相似文献   

CFD数值分析三体船片体位置对阻力及兴波干扰影响     

李响  刘志强  万德成 《海洋工程》2022,40(6):76-82

三体船的水动力性能是目前水动力学研究的热门。对于中高速三体船来说,其静水阻力的很大一部分由兴波阻力构成,而对于兴波最大的影响因素就是片体位置的布局。以一艘圆舭型三体船为研究对象,运用黏流计算流体力学(CFD)方法模拟分析4种不同片体位置对三体船静水阻力和兴波干扰的影响。数值计算采用自主研发的黏流CFD求解器naoe-FOAM-SJTU。数值预报得到三体船静水阻力结果与模型试验结果吻合较好,验证了当前CFD方法预报三体船阻力的可靠性。通过不同片体位置三体船阻力计算发现,方案4的船型方案阻力最优,且通过细节的主片体间兴波干扰流场的结果给出了不同片体布置方案对三体船阻力和兴波的影响。  相似文献   

区域一体化政策对城市高学历人才分布的影响与作用机制——以长三角地区为例     

许泽宁  陈子韬  甄茂成 《地理研究》2022,41(6):1540-1553

人才是城市发展的核心动力,近年来,城市间人才竞争日趋激烈,人才空间配置失衡的问题日益严重。如何通过区域协调发展,促进人才空间分布的优化,成为区域高质量发展的关键。本文以长三角地区为例,基于城市高学历人才规模的估算,剖析区域一体化政策对城市高学历人才分布的影响及作用机制。研究发现：① 长三角就业人口中高学历人才占比逐年提升,由2005年的20.19%增长至2018年的30.89%,呈现出“多中心、中部强、南北弱”的空间分布态势,且极化现象明显;② 相较于其他城市,被纳入区域一体化政策的城市平均多6.81万本科学历人才和0.59万研究生学历人才,中小城市与核心城市受到区域一体化政策的影响更加明显;③ 区域一体化政策主要通过提升城市创新产出和公共服务水平的方式,来影响城市高学历人才的规模和占比。在区域协调发展的战略要求下,本文的研究发现可为城市间人才优化配置和区域治理提供决策支持。  相似文献