Calculation of the added mass of circular cylinders in shallow water     

David Clarke   《Ocean Engineering》2001,28(9):354

The added mass of hull section shapes must be known, in order to carry out any studies of ship motions, which may be associated with either seakeeping or manoeuvring. Determination of the added mass in deep water can involve conformal mapping or surface singularity distributions. However, in shallow water the problem of determining the added mass is made more difficult by the proximity of the seabed. In this paper, three approaches to the problem of finding the added mass of semi-circular sections are explored. Although there is no known exact solution to this problem, the relationships given by the three methods are compared and the approximate nature of the solutions is examined. The first method is a series solution, which is taken here to include more terms than are normally given in the existing literature. The other two solutions are considered to be new, and so are given in some mathematical detail.  相似文献   

山东惠民凹陷中央隆起带古近系沙河街组层序地层特征及控制因素研究   总被引：2，自引：0，他引：2  

杨剑萍  许正豪  姜在兴  操应长  陈发亮 《沉积学报》2003,21(4):670-674

结合山东惠民凹陷中央隆起带古近系层序地层学研究,依据层序中湖平面变化特点和相应的沉积物特征,提出了构造运动和气候是本区层序地层发育的主要控制因素。中央隆起带古近系沙河街组二、三、四亚段可划分为 3种层序类型,即断陷初期型、强断陷期型和断陷后期型层序。由于构造运动导致湖岸线向盆地方向退缩,产生下降体系域,本次研究采用了体系域的四分法,即一个完整层序由低位、湖侵、高位和下降四个体系域组成,并且层序界面位于湖平面最大下降的位置,介于下降域和低位域之间。断陷初期红色地层层序,受气候因素控制明显,既不同于冲积地层层序,也不同于正常湖相地层层序,在层序演化上有其独特的特点。受构造作用和沉积物补给条件的影响,研究区发育三种沉积密集段,不同类型的沉积密集段在层序中所处位置不同,控制着不同的烃源岩厚度和油气资源储量。  相似文献   

松辽盆地白垩系的密集段及海水进侵的新证   总被引：37，自引：0，他引：37  

叶淑芬  魏魁生 《地球科学》1996,21(3):267-271,T001

在总结松辽盆地白恶系层地层特征的基础上，阐述了密集段的地质学和地球物理学标志，经分析，大多数重要反射与密集段相关而并非是层序边界，根据扫描电镜分析结果，在密集段中首次发现了钙质超微化石，为区内白垩纪海水进侵的提供了新的证据，由稳定同位素分析，密集段形成了缺氧，相对可容纳空间最大及水体最深时期。  相似文献   

Composition and Assemblage Characteristics of Magnetic Minerals in Layer S_(5-1) of Xifeng and Duanjiapo Sections     

贾蓉芬  彭先芝  周正  刘德汉  王冠鑫  王德强 《中国地球化学学报》2004,23(3)

Magneticmineralsintheloess paleosolseriesaccountforabout 1 % -2 %ofthetotal (LiuTungshengandZhangZhonghu ,1 962 ) .Duetotheiraerolianorigin ,themagneticmineralsarecomplicatedincomposition ,largeingrainsizerange ,andsignificantlydifferentincrystallinity .Asaresult,researchonthesemagneticmineralswouldbesetwithalotofdifficulties.Previousre searchersemployedopticalmicroscopic ,X raydiffractionandM ssbauerspectrometrictechniquestostudythemagneticmineralsintheloess paleosolseries,andchieflyontheb…  相似文献   

Towards more systematic perceptual model development: a case study using 3 Luxembourgish catchments          下载免费PDF全文

Sebastian Wrede  Fabrizio Fenicia  Núria Martínez‐Carreras  Jérôme Juilleret  Christophe Hissler  Andreas Krein  Hubert H. G. Savenije  Stefan Uhlenbrook  Dmitri Kavetski  Laurent Pfister 《水文研究》2015,29(12):2731-2750

The synthesis of experimental understanding of catchment behaviour and its translation into qualitative perceptual models is an important objective of hydrological sciences. We explore this challenge by examining the cumulative understanding of the hydrology of three experimental catchments and how it evolves through the application of different investigation techniques. The case study considers the Huewelerbach, Weierbach and Wollefsbach headwater catchments of the Attert basin in Luxembourg. Subsurface investigations including bore holes and pits, analysis of soil samples and Electrical Resistivity Tomography measurements are presented and discussed. Streamflow and tracer data are used to gain further insights into the streamflow dynamics of the catchments, using end‐member mixing analysis and hydrograph separation based on dissolved silica and electrical conductivity. We show that the streamflow generating processes in all three catchments are controlled primarily by the subsolum and underlying bedrock. In the Huewelerbach, the permeable sandstone formation supports a stable groundwater component with little seasonality, which reaches the stream through a series of sources at the contact zone with the impermeable marls formation. In the Weierbach, the schist formation is relatively impermeable and supports a ‘fill and spill’‐type of flow mechanism; during wet conditions, it produces a delayed response dominated by pre‐event water. In the Wollefsbach, the impermeable marls formation is responsible for a saturation‐excess runoff generating process, producing a fast and highly seasonal response dominated by event water. The distinct streamflow generating processes of the three catchments are represented qualitatively using perceptual models. The perceptual models are in turn translated into quantitative conceptual models, which simulate the hydrological processes using networks of connected reservoirs and transfer functions. More generally, the paper illustrates the evolution of perceptual models based on experimental fieldwork data, the translation of perceptual models into conceptual models and the value of different types of data for processes understanding and model representation. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

香龙山背斜几何学、运动学及成因机制          下载免费PDF全文

邓铭哲何登发  李英强张煜颖 张旭亮 《地质科学》2018,(1):289-307

华南板块北侧大巴山构造带和内部雪峰山构造带的关系是华南板块陆内构造变形研究的重要内容。香龙山背斜位于大巴山构造带和雪峰山构造带之间,记录了两构造带相互复合、相互协调的重要信息。为研究香龙山背斜的几何学、运动学特征,分析其形成机制,本次研究利用香龙山地区最新的地震剖面,结合地质图分析、浅表地质剖面绘制等手段,取得了如下结论：1） 香龙山背斜为一短轴状背斜,背斜具有较为宽阔、平坦的顶部和较短的两翼,其西南侧发育构造鼻;2） 香龙山背斜的主要运动学模型为下部断层转折褶皱与上部构造楔复合的模型,其地层变形受到基底物质堆叠抬升的影响;3） 香龙山背斜形成于晚侏罗世-早白垩世,在古近纪遭受改造,这两个变形时期分别对应了香龙山背斜形成现今形态的两个阶段。香龙山背斜南北方向上缩短了11.4 km,缩短率为22.7%;4） 香龙山背斜是在雪峰山构造带北向挤压作用下,由来自大巴山构造带、雪峰山构造带的共同作用力形成的,后期改造作用可能受控于青藏高原了隆升对整个中国中、西部的影响。  相似文献   

碳酸盐岩铸体薄片面孔自动提取研究     

杜相仪  董少群  曾联波  何娟  孙福亭 《地质论评》2021,67(6):1910-1920

岩石孔隙是储层储集油气的重要场所,通过铸体薄片进行岩石孔隙结构分析对储层质量评价具有重要意义。碳酸盐岩孔隙结构较为复杂,铸体薄片图像中存在大量噪声和干扰因素,致使常规方法面孔提取效果不佳,因此本文引入一种多阈值铸体薄片面孔自动提取方法（ctsPore方法）进行孔隙区域提取和面孔率估计,方法综合利用HSV色彩空间中不同参数提取孔隙区域。本文针对碳酸盐岩储层的特点确定了一套ctsPore阈值参数,以解决溶蚀孔与噪声易混淆的问题。实验以伊拉克A油田中新统 Asmari组A段碳酸盐储层为例对所使用算法进行了效果检验。算法精度和效率分析实验表明,基于ctsPore方法的碳酸盐岩铸体薄片面孔提取误差小于0.24%。全井段铸体薄片分析结果表明,A段储层面孔率范围主要分布在6%~8%,储层较为致密,从上到下A1~A3小层的储层平均面孔率分别为6. 9%、11.7%、5.4%,与储层物性、沉积微相和岩性等纵向分布规律较为吻合。  相似文献   

Geological characteristics and ore genesis of Houfangzi graphite deposit in Northwestern Hebei Province     

ZHANG Xingkang  FAN Yupeng  JIN Song  JIA Zhenghai 《中国地质调查》2021,7(6):20-26

Houfangzi graphite deposit is located in the middle of the graphite metallogenic belt in the northern margin of North China Block in Hebei Province, which belongs to regional metamorphic type graphite deposit. In this paper, through rock-mineral determination, IP ladder sections and exploratory trench survey, the authors have discussed its metallogenic geological characteristics and ore body characteristics, and analyzed its ore genesis. The research results show that the ore bodies are mainly in the graphitic marble of Dongjingzi Formation of Hongqiyingzi Group, which are stratified and controlled by layers, with NE trend and NNW inclination. The IP anomaly shows that Houfangzi graphite deposit is characterized by low resistance and high polarization. Ore bodies are stable and of big scale, and their fixed carbon content ranges from 1.42% to 3.28%, which has the potential to be a large graphite deposit. The ore-forming material came from granulite and graphite marble, while the regional metamorphism is the main mineralization of Houfangzi graphite deposit, with the enrichment and increasement caused by late magmatic activity and migmatization.  相似文献   

黄河（山东段）悬河稳定性评价   总被引：1，自引：1，他引：0       下载免费PDF全文

郭秀岩  韩祥银  王心兵 《山东国土资源》2009,25(4)

通过黄河（山东段）悬河稳定性影响因素分析,各河段都有决口失稳的可能。该文从区域地壳稳定性、堤基稳定性、河道稳定性3个方面,采用模糊数学综合评判法进行悬河稳定性评价,对河段可能出现的失稳或决口险点及其可能造成的危害性进行分析和预测,初步确定了10处地质险段。  相似文献   

Ultraviolet absorption spectra of some Br-containing haloalkanes     

V. L. Orkin  E. E. Kasimovskaya 《Journal of Atmospheric Chemistry》1995,21(1):1-11

The ultraviolet absorption cross sections were measured for CF₃Br, CF₂ClBr, CF₂Br-CF₂Br, CF₂Br₂, CHF₂Br, CHFBr-CF₃, CH₂Br-CF₃, CHClBr-CF₃ in the wavelength range 190–320 nm at 295 K. The photolysis is concluded to be the minor atmospheric sink for CHF₂Br, CHFBr-CF₃, CH₂Br-CF₃, CHClBr-CF₃.  相似文献