碎冰条件下单点系泊船舶动态响应特性研究     

杨佳东  吕海宁  王晋 《海洋工程》2019,37(2):29-39

为了研究不同单点系泊位置对极地系泊船舶在来冰角度改变时动态响应的影响,运用离散元方法(DEM),计算了船舶在60%密集度下,冰速为1.0 m/s、冰厚为1 m时不同角度的船冰阻力,结合系泊分析软件二次开发功能,计算分析系泊船舶在不同来冰角度和不同系泊位置下受上述冰情影响下的响应。通过对模拟结果与试验结果的对比,认为离散元方法(DEM)的数值模拟结果与试验结果吻合较好;单点系泊位置为距船头L/4时,系泊船舶能以最快速、最稳定的方式对来冰方向的变化做出响应。  相似文献   

Fully Coupled Effects of Hull, Mooring and Risers Model in Time Domain Based on An Innovative Deep Draft Multi-Spar     

李彬彬  欧进萍  滕斌 《中国海洋工程》2010,24(2):219-233

The coupled hull, mooring and riser analysis techniques in time domain are widely recognized as the unique approach to predict the accurate global motions. However, these complex issues have not been perfectly solved due to a large number of nonlinear factors, e.g. forces nonlinearity, mooring nonlinearity, motion nonlinearity and so on. This paper investigates the coupled effects through the numerical uncoupled model, mooring coupled model and fully coupled model accounting mooring and risers based on a novel deep draft multi-spar which is especially designed for deepwater in 2009. The numerical static-offset, free-decay, wind-action tests are executed, and finally three hours simulations are conducted under 100-year return period of GOM conditions involving wave, wind and current actions. The damping contributions, response characteristics and mooring line tensions are emphatically studied.  相似文献   

UHV/VHF波段SAR对次地表层土壤湿度探测与反演     

戚任远 《遥感学报》2009,13(1)

首先采用一层非球形粒子植被模型,计算各波段矢量辐射传输方程Mueller矩阵一阶散射解,对比微扰法所得各波段地表粗糙面直接后向散射解,结果证明L波段植被层的散射对观测结果仍有影响,与下垫土壤粗糙表面的散射不易分离.因此,宜采用更低频率的UHF和VHF波段,对地表和次地表层能有较大的渗透深度,并可忽略植被层影响.接着,运用矢量辐射传输的3层土壤全极化Mueller矩阵解,计算UHF/VHF波段分层土壤的散射与传输,分析该两波段探测深度的差异,证实UHF波段可探测大致10-60cm深处的土壤湿度,而VHF波段探测深度能更大一些.根据第3层中土壤体湿度变化0.1时能否引起土壤表面观测的后向散射系数变化0.1dB这一判据,分析VHF波段反演第3层土壤体湿度的必要条件,证实当第2层的体湿度较小时(<0.25)才能反演层3的体温度.基于UHF/VHF两波段探测深度的差异,耗散土壤层的贡献有不同的权重,先后采用UHF和VHF,迭代法实现3层土壤湿度廓线反演.误差分析表明,该方法是有意义的.  相似文献   

Theoretical Model and Dynamic Analysis of Soft Yoke Mooring System   总被引：2，自引：0，他引：2  

肖龙飞  杨建民  杨立军  李欣 《中国海洋工程》2008,22(2):195-204

As a popular solution for mooring an FPSO （Floating Production, Storage and Offloading） permanently in shallow water, the soft yoke mooring system has been widely used in ocean oil production activities in the Bohai Bay of China. In order to simulate the interaction mechanism and conduct dynamic analysis of the soft yoke mooring system, a theoretical model with basic dynamic equations is established. A numerical iteration algorithm based on error estimation is developed to solve the equations and calculate the dynanfic response of the mooring system due to FPSO motions. Validation is conducted by wave basin experimentation. It is shown that the numerical simulation takes only a few iteration times and the final errors are small. Furthermore, the calculated results of both the static and dynamic responses agree well with those ones obtained by the model test. It indicates that the efficiency, the precision, the reliability and the validity of the developed numerical algorithm and program are rather good. It is proposed to develop a real-time monitoring system to further monitor the dynamic performance of the FPSO with a soft yoke mooring system under various real sea environments.  相似文献   

热带太平洋次表层三维海温距平场的EOF分析     

张立峰  许建平  何金海 《海洋学研究》2008,26(3):35-43

应用太平洋次表层海温距平资料构造了一个立体的西低东高的四级阶梯模型,使用EOF方法对此模型进行时空分解,重点讨论了分解结果与ENSO循环的关系,并对Nino 3距平指数进行试预报,结果表明,用 EOF分解的第一主分量代表暖池-厄尔尼诺(拉尼娜)模态,第二主分量代表次表层温度距平的东西运移模态,厄尔尼诺事件正是东西运移模态突变的结果.时滞相关分析估算,一次ENSO循环的平均周期约为41个月,厄尔尼诺、拉尼娜模态与温度距平的东西运移模态的位相差平均约为9.7个月.应用逐步回归方法得到超前Nino 3距平指数3、6和12个月的3个预报方程.预报结果表明,第一、第二时间系数对Nino 3距平指数均具有一定的预报价值,预报时效可达1 a左右.  相似文献   

天然气水合物的上界面——硫酸盐还原-甲烷厌氧氧化界面   总被引：4，自引：0，他引：4  

栾锡武 《海洋地质与第四纪地质》2009,(2)

定义了海域天然气水合物成矿带的上界面。指出在地球深部存在最原始的、从根本上不依靠光合作用来生存的生命系统。根据对ODP岩心样品中微生物数量的统计,海底以下沉积层中的生物数量可能占据全球原核生物总量的70%,其生物总碳量和地球表面所有植物的碳总量相当。地球内部如此巨大的生物总量应该在地壳中的气体分布等方面起着重要作用。甲烷在地壳层中广泛存在,并主要是微生物成因的。微生物产甲烷的途径主要有两个,一是二氧化碳还原,另一个是醋酸盐发酵。相应地,参与产甲烷的微生物菌群主要是产甲烷菌和食醋酸菌。甲烷在沉积层中的厌氧氧化是一个不争的事实。该过程发生在海底以下一个非常局限的区带,称为硫酸盐还原-甲烷厌氧氧化区带。通常,这个区带很窄,仅为一个面,因此,硫酸盐还原-甲烷厌氧氧化区带又称硫酸盐还原-甲烷厌氧氧化界面。这是一个基本的生物地球化学界面,在功能上它起到屏蔽甲烷向海底和大气逸散的作用,是一个巨大的甲烷汇。甲烷的厌氧氧化同样是一个由微生物介导的过程,参与此过程的微生物主要是食甲烷古菌和硫酸盐还原菌。硫酸盐还原-甲烷厌氧氧化界面在海洋沉积层中一般深可达海底以下上百米,浅可至海底。此界面为天然气水合物的上界面,该界面以上没有甲烷...  相似文献   

深海系泊法向承力锚模型实验系统     

盛志刚  刘海笑 《海洋技术学报》2009,28(1)

法向承力锚是一种新型的拖曳嵌入式系泊基础.这种锚的工程应用仅有10 a时间.国内在此项技术上尚属空白.通过实验系统的设计,介绍了针对这种新型拖曳锚展开模型实验研究的实验平台.利用一些新型传感器和巧妙的机件设计,不仅实现了实验量测方法的创新,而且达到了经济实用的目的.实验结果也验证了整个系统设计的可靠性.  相似文献   

Estimating macropore and matrix flow using the hydrograph separation procedure in an experimental forest plot     

Jos Nvar  Donald J. Turton  Edwin L. Miller 《水文研究》1995,9(7):743-753

This study was conducted to estimate macropore space, macropore flow and matrix flow in an experimental forest plot in the Ouachita Mountains of Arkansas. Lateral soil water fluxes and soil capillary potentials were observed in the isolated plot during applied rainfall experiments. Rainfalls were applied 17 times during the period 17 July to 10 October 1991. The subsurface hydrograph separation technique was used to estimate macropore space, macropore flux and matrix flux. The boundary between macropore and matrix flow was statistically determined by covariance analysis. The maximum estimated lateral macropore space was approximately 0.006 (cm³ cm^?3). The maximum estimated lateral macropore and matrix flow were 0.042 and 0.00066 cm s^?1, respectively. This report also emphasizes the need for further research on the hydrograph separation procedure for estimating macropores and macropore flow.  相似文献   

The Influence of Surface Inhomogeneities On Deep Electromagnetic Soundings of the Earth     

E. B. Fainberg  B. Sh. Singer 《Geophysical Journal International》1987,90(1):61-73

Summary. Asymptotic expressions for components of the electromagnetic field of a grounded electric dipole are considered for the model consisting of a thin surface-layer overlapping a stratified medium with a highly resistive screen on the roof. It is shown that the method of spatial derivatives makes it possible to obtain proper estimates of the impedance at distances of r ≥|λ₀| from the nearest edge of the surface anomaly (|λ₀| being the effective depth of the field penetration in the underlying section). the magnetotelluric methods allow one to obtain the true values of impedance, provided r ≥ max {|λ₀|, |/( S ⁻¹+ Z ⁻₀|^1/2} where S is the integrated conductivity of the surface layer, is the transverse resistance of the screen, and Z ⁻₀ is the Tikhonov—Cagniard impedance for the medium underlying the surface layer.  相似文献   

Reflection of neotectonic processes in the subsurface hydrosphere of the Verkhnii Amur region     

A. T. Sorokina  A. P. Sorokin  M. A. Serov 《Russian Journal of Pacific Geology》2008,2(6):499-511

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