Motions of a spherical submarine in waves     

Shen Wang 《Ocean Engineering》1986,13(3)

The free motions in waves of submerged vehicles with a spherical hull from but different metacentric heights are sought. The problem is analysed by considering the submerged vehicle as a neutrally buoyant sphere. The solutions to two independent problems, namely the radiation problem and the diffraction problem, are required. Nondimensional parameters known as the added mass, damping and diffraction coefficients for neutrally buoyant spheres are derived and computed values of these coefficients are presented in tabulated form. The responses of surge, heave and pitch are explicitly expressed by these coefficients and the metacentric height of the submarine. A spherical submarine is practically motionless relative to the particle movement of waves except at the vicinity of reasonant frequency, which is governed by the value of metacentric height.  相似文献   

影响计算海湾内台风波浪的诸因素     

李少英  沈建平 《海洋工程》1997,(1)

本文阐明了影响计算海湾内台风波浪的重要因素，使用我们目前已改进了的模式，可克服以往的计算缺陷，而使计算效果达到最佳。同时，阐述了不同海湾、不同的地理环境对台风浪波能的消衰不同。并强调了台风增水对台风浪计算的影响，其也直接影响着工程设计波浪参数的合理选取。  相似文献   

南黄海中部的低能沉积环境   总被引：17，自引：3，他引：17  

申顺喜  李安春  袁巍 《海洋与湖沼》1996,27(5):518-523

利用沉析法和筛板法及显生微镜等方法，对１９８８年以来采自南黄海表层和浅孔样品进行粒度，矿物及生物组合等多种分析，应用沉积物的粒度参数来判别沉积环境。研究结果表明，南黄海陆架的沉积环境十分复杂。在其中部，有一个低能量的沉积动力活动区，它的各种属性都与南黄海冷水团密切相关。  相似文献   

西沙群岛鱼类复殖吸虫 Ⅱ     

申纪伟 《海洋科学集刊》1985,(24):167-180

作者继续整理1977年在西沙群岛采集的鱼类复殖吸虫标本,共得4科19种,其中有7新种。分别描述于后(新种的鉴定见表1)。其它为地区或宿主新纪录(种名见表2)。测量一律用毫米,卵子为微米。模式标本保存在中国科学院海洋研究所。  相似文献   

Nonlinear Analysis of Nearshore Wave Height Variation Due to Shoaling     

Shen Xianrong Engineer  Zhejiang Provincial Design Institute of Communications  Hangzhou 《中国海洋工程》1995,(4)

Wave formulae derived from the dispersion relation for cnoidal waves are used to find an analytical solution to the problem of nearshore wave height variation on a simple topography, i. e., with an incrementally constant slope. The solution accounts for shoaling, frictional dissipation and will be sufficiently accurate for practical purposes considering the simplified assumptions which are necessary for the treatment of this problem by any method.  相似文献   

饥饿对日本囊对虾幼体发育、摄食及存活的影响   总被引：4，自引：0，他引：4  

李静  马甡 《海洋湖沼通报》2005,(2):61-65

本实验研究了饥饿对日本囊对虾蚤状幼体Ⅰ期发育、摄食及存活的影响。结果表明．饥饿对对虾幼体的变态存活有显著影响，饥饿时间与变态率及变态时间呈线性关系．饥饿对日本囊对虾幼体首次摄食影响显著。本实验中，日本囊对虾的蚤Ⅰ幼体的PNR100应为40h。  相似文献   

Laboratory Studies on Property Changes in Surrounding Clays Due to Installation of Deep Mixing Columns   总被引：6，自引：0，他引：6  

Shui-Long Shen  Xing-Chun Huang  Shou-Ji Du  Jie Han 《Marine Georesources & Geotechnology》2003,21(1):15-35

This paper has identified six major factors causing property changes in surrounding soils during and after installation of deep mixing columns: soil thixotropy, soil fracturing, cement penetration and diffusion, cementation, consolidation, and heating. Laboratory tests were performed to investigate the effects of soil thixotropy, soil fracturing, and cementation in a soft marine clay, Ariake clay. Laboratory tests were conducted to evaluate property changes in surrounding clays due to installation of deep mixing columns. Test results showed that an influential zone of property changes existed in surrounding clay ranging from the edge of the columns to the distance of about twice the radius of the columns. Within this influential zone, water content decreased as samples neared the columns, while pH values and electric conductivity increased. Test results also showed that undrained shear strengths of the surrounding clays decreased during mixing but regained after a 7-day curing period and continued increasing during 28 days in this study.  相似文献   

浙东沿岸多港口台风增水预报方法的探讨     

应仁方  沈雪龙 《海洋学报》1982,4(3):259-266

浙东海岸为东海沿岸遭受台风袭击严重的地段之一.而台风增水所导致的暴潮水位往往又是造成灾害的主要原因.因此,研制或改进出一种适应该地区台风增水的预报技术,并使之投入具体的预报业务,仍是当前一个迫切的研究课题.为此,我们在研究了“Pore模式”的基础上,结合我国具体情况,设计了东海海平面气压网格用于热带风暴(台风)增水的预报,建立一种多港口且具一定时效的预报模式.本文以浙东沿岸两个港口为例,作了初步检验,结果较好.  相似文献   

Abundant seamounts of the Rano Rahi seamount field near the Southern East Pacific Rise, 15° S to 19° S     

Daniel S. Scheirer  Ken C. Macdonald  Donald W. Forsyth  Yang Shen 《Marine Geophysical Researches》1996,18(1):13-52

A widespread seamount province, the Rano Rahi Field, is located near the superfast spreading Southern East Pacific Rise (SEPR) between 15°–19° S. Particularly abundant volcanic edifices are found on Pacific Plate aged 0 to 6.5 Ma between 17°–19° S, an area greater than 100,000 km². The numbers of seamounts and their volume are several times greater than those of a comparablysurveyed area near the Northern East Pacific Rise (NEPR), 8°–17° N. Most of the Rano Rahi seamounts belong to chains, which vary in length from 25 km to >240 km and which are very nearly collinear with the Pacific absolute and relative plate motion directions. Bends of 10°–15° occur along a few of the chains, and some adjacent chains converge or diverge slightly. Many seamount chains have fluctuations in volume along their length, and statistical tests suggest that some adjacent chains trade-off in volume. Several seamount chains split into two lines of volcanoes approaching the axis. In general, seamount chains composed of individual circular volcanoes are found near the axis; the chains consist of variably-overlapping edifices in the central part of the survey; to the west, volcanic ridges predominate. Near the SEPR, the volume of nearaxis seamount edifices is generally reduced near areas of deflated cross-sectional area of the axial ridge. Fresh lava flows, as imaged by sidescan sonar and sampled by dredging, exist around some seamounts throughout the entire survey area, in sharp contrast to the absence of fresh flows beyond 30 km from the NEPR. Also, the increases in seamount abundance and volume extend to much greater crustal ages than near the NEPR. Seamount magnetization analysis is also consistent with this wider zone of seamount growth, and it demonstrates the asynchronous formation of most of the seamount chains and volcanic ridges. The variety of observations of the SEPR seamounts suggests that a number of factors and mechanisms might bring about their formation, including the mantle upwelling associated with superfast spreading, off-axis mantle heterogeneities, miniplumes and local upwelling, and the vulnerability of the lithosphere to penetration by volumes of magma. In particular, we note the association of extensive, recent volcanism with intermediate wavelength gravity lineaments lows on crust aged 6 Ma. This suggests that the lineaments and some of the seamounts share a common cause which may be related to ridge-perpendicular asthenospheric convection and/or some manner of extension in the lithosphere.  相似文献   

长江口区营养盐的分布特征及三峡工程对其影响   总被引：9，自引：0，他引：9  

沈志良  陆家平  刘兴俊  刁焕祥 《海洋科学集刊》1992,(33):109-130

在长江口海区,长江冲淡水、台湾暖流、黄海冷水等多种水系混合、交汇,错综复杂。对河口营养盐分布变化规律的研究,将为河口环境和生态变化提供可靠的依据,营养盐作为长江口这一世界著名渔场的化学物质基础具有重要意义。本文通过对长江口及其附近海域的周年观察,讨论了各种营养盐(包括磷、硅和氮)的时空变化规律和它们在河口的转移过程,估算了营养盐的年输出量,并提出了长江流量和营养盐输出量之间的关系,初步预报了三峡工程对长江口营养盐可能产生的影响。  相似文献