Coupled dynamic analysis for wave interaction with a truss spar and its mooring line/riser system in time domain     

M. Yang  B. Teng  D. Ning  Z. Shi 《Ocean Engineering》2012

A full time-domain analysis program is developed for the coupled dynamic analysis of offshore structures. For the hydrodynamic loads, a time domain second order method is developed. In this approach, Taylor series expansions are applied to the body surface and free-surface boundary conditions, and the Stokes perturbation procedure is then used to establish the corresponding boundary value problems with time-independent boundaries. A higher-order boundary element method (HOBEM) is developed to calculate the velocity potential of the resulting flow field at each time step. The free-surface boundary condition is satisfied to the second order by fourth order Adams–Bashforth–Moultn method. An artificial damping layer is adopted on the free surface to avoid the wave reflection. The mooring-line/tendon/riser dynamics are based on the rod theory and the finite element method (FEM), with the governing equations described in a global coordinate system. In the coupled dynamic analysis, the motion equation for the hull and dynamic equations for mooring-lines/tendons/risers are solved simultaneously using the Newmark method. The coupled analysis program is applied for a truss Spar motion response simulation. Numerical results including motions and tensions at the top of mooring-lines/risers are presented, and some significant conclusions are derived.  相似文献   

绝对重力仪测量结果的振动划线处理方法初步研究   总被引：2，自引：0，他引：2       下载免费PDF全文

龙剑锋  黄大伦  滕云田  吴琼  郭欣 《地震学报》2012,34(6):865-872

针对自主研发的高精度绝对重力仪样机测量结果中引入的振动误差, 提出了一种全新的振动抑制算法．本算法利用一簇斜率相同的平行直线与记录到的参考棱镜振动曲线相交, 通过提取这些交点的时间信息, 确定落体下落轨迹上进行重力加速度计算的时间和位移坐标． 然后, 利用最小二乘算法获取测点的绝对重力加速度值．对不同重力加速度值的适用性和不同类型振动干扰的抑制效果模拟计算发现, 对于优势频率大于0.2 Hz, 峰峰值小于500 counts的干扰, 算法可以有效提高测量结果的系统偏差和测量精度．最后, 实际实验样机的测量结果表明, 本算法使最终测量精度提高了一倍, 为绝对重力仪的小型化和流动测量提供了软件技术支持。   相似文献   

基于组件模型技术的地磁数据干扰抑制系统     

谢凡  滕云田  徐沁 《地震地磁观测与研究》2012,33(2):152-158

地磁观测数据中的人工干扰抑制等预处理工作需要一套高效、便捷、交互性好的预处理系统.将基于Matlab的核心干扰识别和抑制算法以组件对象技术的形式提供给其他编程语言调用,在系统架构上采用Windows DNA架构,在界面的开发上采用微软成熟的MFC架构.同时,给出系统架构模型及关键技术实现.该系统在实际应用中取得良好效果.  相似文献   

地震前兆串口通讯设备的网络接入方案与实现   总被引：1，自引：0，他引：1  

王晨  滕云田  王晓美  李庆武  李明威  赵银刚  谭婧 《地震地磁观测与研究》2012,33(5):244-249

针对地震前兆台网在不同时期项目建设时的技术限制,对前兆台网技术系统进行整合,在全国开展“九五”及模拟观测系统整体并人“十五”系统的改造升级工作。其主要内容包括台站网络改造和“九五”仪器接人改造两部分。对于具有仪器改造任务而不具备网络条件的台站进行网络通讯改造;通过增加地震前兆通信协议转换器和升级数据采集器两种方式进行“九五”仪器的接人改造改造后的仪器可以通过网络进行观测数据的汇集,从而实现前兆台网统一的运行监控、采集数据、存储、交换、管理和服务。  相似文献   

基于三角网格的有限差分法叠后逆时偏移   总被引：1，自引：1，他引：0  

郭书娟  李振春  孙小东  叶月明  滕厚华  李芳 《应用地球物理》2008,5(2):115-120

Compared with other migration methods, reverse-time migration is based on a precise wave equation, not an approximation, and performs extrapolation in the depth domain rather than the time domain. It is highly accurate and not affected by strong subsurface structure complexity and horizontal velocity variations. The difference method based on triangular grids maintains the simplicity of the difference method and the precision of the finite element method. It can be used directly for forward modeling on models with complex top surfaces and migration without statics preprocessing. We apply a finite difference method based on triangular grids for post-stack reverse-time migration for the first time. Tests on model data verify that the combination of the two methods can achieve near-perfect results in application.  相似文献   

Microbial carbonates in Holocene beachrocks,Shuiweiling, Luhuitou Peninsula,Hainan Island   总被引：2，自引：0，他引：2  

Teng JianBin  Shen JianWei 《中国科学D辑(英文版)》2008,51(1):30-40

Two research methods, geomicrobiology and carbonate sedimentology, were adopted to study the microbial carbonates in the beachrocks, Shuiweiling, Luhuitou, Sanya City, Hainan Island. The results indicate that microbial carbonates occur in Shuiweiling beachrocks and cements related to microbial activitives are common. Microbial carbonates were mainly developed on the surfaces of coral skeletons and within the coral (fragments and shivers) skeletal cavities,and rarely grew in interspaces formed by coral and other biological detritus. The growth morphologies of microbial carbonates are various, including stromatolitic lamination, thin crusts, dome-like, and microbialites. Microbial carbonates commonly trap fine-sized bioclasts, contain tubular filaments, and show laminated growth striation. Microbial carbonates within the coral skeletal cavities are generally stromatolitic cone-shaped, with a random growth direction along the bearing of trend of cavities, showing distinct growth laminae and recognizable growth phases. It is a special growth pattern of crypt microbial carbonates. Microbial cements occur mainly in shape of needle cement, calcified filaments, microborings, and calcified framboidal spheres. The needle cement is the most common type. These microbial cements indicate that microbial activities and microbial carbonates played an important role in beachrock formation in which carbonates were dominant components and the climate of tropical ocean monsoon was influential. Such microbial carbonates and microbial cementation have not been reported here from beachrocks along the northern shorelines of the South China Sea. The results support a clear microbial origin for certain carbonate cements in beachrocks, confirm that microbial carbonates are a significant contributor to carbonate sedimentation, and widen the knowledge of beachrocks from a new field.  相似文献   

我国西北地区近50年降水和温度的变化   总被引：135，自引：9，他引：126  

于淑秋  林学椿  徐祥德 《气候与环境研究》2003,8(1):9-18

用近50年的每月温度和降水资料研究了我国西北地区的气候变化.结果表明:(1)该地区在1986年附近发生了一次明显的气候跃变,要比全国气候跃变晚6～8年;(2)跃变后比跃变前全区年平均气温上升了0.51℃,冬季上升了1.27℃;(3)跃变后比跃变前全区年降水总量上升了5.2%,夏季上升了6.8%.进而讨论了温度和降水的增加对该地区生态环境的影响.  相似文献   

Analysis of coupled axial and lateral deformation of roots in soil     

Gerrit J. Meijer  David Muir Wood  Jonathan A. Knappett  Glyn A. Bengough  Teng Liang 《国际地质力学数值与分析法杂志》2019,43(3):684-707

Plant roots can help to stabilise slopes. Existing analytical models to predict their mechanical contribution are however limited: they typically focus on the ultimate limit state, employ various empirical factors, and ignore much of the underlying root-soil interaction. A new model was developed based on large deflection Euler-Bernoulli elastic beam theory that can be used to study the mobilisation of root strength under various loading conditions (direct shear and pull-out). Both lateral and axial loading of the root by the soil were incorporated, based on existing methodologies for foundation piles (p-y and t-z curves). The model is able to take the key parameters into account (root biomechanical properties, root architectural properties, and soil properties) while remaining quick to solve using a numerical boundary value problem solver. The model was compared with experimental direct shear test data using various root analogues (rubber, plastic, and wood) in dry sand with various densities and effective stress levels and was able to accurately predict the measured shear force-displacement behaviour. Comparison with experimentally measured pull-out force-displacement curves using rubber and wooden root analogues with various architectures in dry and partially saturated sands was also satisfactory. In the future, this model can aid with addressing long-standing problems in the root-reinforcement community: quantifying the effect of (sequential) mobilisation of root strength in direct shear, the effect of the angle at which the root crosses a shear plane, the effect of root topology on root-reinforcement or the effect of root bending, and root shear shear forces on root-reinforcement.  相似文献   

班公湖-怒江成矿带西段角西石英脉型钨矿床地质特征及黑钨矿地球化学特征   总被引：3，自引：1，他引：2  

王勇  王立强  范源  李申  旦真王修  郑斯伦  高腾 《岩石学报》2019,35(3):724-736

角西矿床是班公湖-怒江成矿带上目前发现的首例石英脉型钨矿床。本文对该矿床的地质特征及黑钨矿微量、稀土元素进行了系统的研究。结果表明,角西矿床主要发育与中新世花岗岩密切相关的含黑钨矿(±白钨矿)石英脉,矿脉主要受张性裂隙控制,宽度在0. 02～2m之间,"五层楼"分带模式较为明显,蚀变类型主要为云英岩化和角岩化。矿化可以分为氧化物阶段、硫化物阶段和萤石-碳酸岩阶段。与华南同类型矿床相比,角西黑钨矿的稀土元素含量极低(∑REE=0. 560×10~(-6)～1. 186×10~(-6)),具有较为明显的正Eu异常。黑钨矿中相对富集Sc元素(平均31. 15×10~(-6))的特征表明成矿流体富含F-和/或PO_4~(3-)离子。以上研究成果不仅有助于加深该矿床成因的认识,而且为后续矿床勘查提供了重要信息。  相似文献   

Hurricane flood risk assessment for the Yucatan and Campeche State coastal area     

Rey  Wilmer  Mendoza  E. Tonatiuh  Salles  Paulo  Zhang  Keqi  Teng  Yi-Chen  Trejo-Rangel  Miguel A.  Franklin  Gemma L. 《Natural Hazards》2019,96(3):1041-1065

Natural Hazards - In this study, the first ever Sea, Lake, Overland Surges from Hurricanes (SLOSH) grid was built for the Yucatan Peninsula. The SLOSH model was used to simulate storm surges in the...  相似文献