A New Pursuit Mode of Nonlinear Wave Surface

The numerical mode of nonlinear wave transformation based on both the Laplace equation for water field and the Bemoulli equation for water surface is a kind of time-domain boundary problem with initial conditions. And the basis for establishing the numerical mode of nonlinear wave in time domain is to trace the position of wave free surface and to calculale the instantaneous surface height and surface potential function. This paper firstly utilizes the ‘0-1‘ combined BEM to separate the boundary by means of discretization of Green‘ s integral equation based on the Laplace equation, then separates the free surface of wave with FEM and derives the FEM equation of wave surface that satisfies the nonlinear boundary conditions. By jointly solving the above BEM and FEM equations, the wave potential and surface height could be obtained with iteration in time domain. Thus a new kind of nonlinear numerical mode is established for calculating wave transformation. The wave test in the numerical wave tank shows that the numerical simulation with this mode is of high accuracy.     

基于雷达海冰图像互相关的冰漂流场测量

我国的渤海和黄海北部在每年冬季都出现不同程度的冰情,它直接影响结冰海区的石油平台、船舶以及港口等设施的正常作业,对海冰的观测与预报随着上述海区的开发利用越发显得重要,利用航海雷达连续准确地跟踪海冰漂移运动轨迹,是当今观测、调查、研究冰漂流移动规律的有效方法之一,我国的科研人员利用雷达成像技术对渤海的冰情进行了长期的雷达海冰观测、研究,在由雷达海冰图像对海冰的物理特征的识别、分类以及冰漂流场测量方面取得了一些进展[1-4]。     

A New Probability of Detection Model for Updating Crack Distribution of Offshore Structures

1 .IntroductionNondestructiveinspection (NDI)isveryimportantforensuringthereliabilityofoffshorestructuresintheirservicelives (Lauraetal.,1 996 ) .Itiswellknownthatdetectionofflawsinvolvesconsider ablestatisticaluncertainties.Asaresult,theprobabilityofdetection (POD)forallflawsofagivensizehasbeenusedintheliteraturetodefinethecapabilityofaparticularNDItechniqueinagivenen vironment.SincethedataofPODusuallyscatterlargely ,itisdifficulttodeterminewhichmodelfitstheavailabledatabest.Thismodelun…     

对虾雄性交接器联合缘上小钩的研究

本文通过扫描电镜的观察,研究了对虾科中5个属10种虾的雄性交接器联合缘上的小钩,对小钩的形态特征及小钩的机能进行了分析和描述。研究表明,小钩的研究将为对虾形态分类工作提供新的参考依据。     

VERIFICATION OF INTERNAL WAVES IN OFFSHORE AREAS BY MEANS OF CURRENT OBSERVATIONS

Based on the shear effect of internal wave currents in stratified fluid, the necessary condition for the possible existence of an internal wave and the sufficient condition under which there will be no internal wave are deduced starting from the continuity equation of incompressible fluid. The above two conditions are verified by the measured results from vertical current meter arraies at some observation stations in the Bohai Sea and the South Huanghai Sea. In the treatment of measured results, first of all, the tidal period components are separated from the measured currents by Fourier-analysis method, and then the internal wave currents of tidal period from the tidal period components in the light of some considerations. The analytical results of observed currents are well consistent with theoretical analysis. Furthermore, one can also deduce some features of internal waves therefrom. Consequently, it is concluded that the observation from a vertical current meter array is an important means to verif     

A New Approach to High-Order Boussinesq-Type Equations with Ambient Currents

A new approach to high-order Boussinesq-type equations with ambient currents is presented. The current velocity is assumed to be uniform over depth and of the same magnitude as the shallow water wave celerity. The wave velocity field is expressed in terms of the horizontal and vertical wave velocity components at an arbitrary water depth level. Linear operators are introduced to improve the accuracy of the kinematic condition at the sea bottom. The dynamic and kinematic conditions at the free surface are expressed in terms of wave velocity variables defined directly on the free surface. The new equations provide high accuracy of linear properties as well as nonlinear properties from shallow to deep water, and extend the applicable range of relative water depth in the case of opposing currents.     

海沧邻近海域表层沉积物中重矿物研究

对厦门海沧邻近海域表层沉积物中的重矿物(0．063～0．125mm粒级)进行了分析和研究，结果表明该粒级的重矿物共计49种，其优势和特征矿物为磁铁矿、赤铁矿、褐铁矿、绿帘石、铁铁矿、角闪石、锆石、红柱石等；重矿物的平均质量分数为9．56％；根据重矿物的分布和含量，并结合主要标志矿物的颗粒百分含量和分布特征，将该海域划分为5个矿物组合区，根据各区的矿物组合类型分析了该海域的物质来源及影响重矿物分布和组合的因素，进而探讨了九龙江河口湾和厦门西港海湾的沉积环境。     

西太平洋暖池变异及其对西太平洋次表层海温场的影响

应用热带太平洋上层XBT温度资料,分析研究了西太平洋暖池区(0°～16°N,125°～145°E)上层海洋的变化特征以及与西太平洋次表层海温场之间的关系.研究表明,西太平洋暖池区的垂向温度存在显著的年际变化,尤其在次表层(120～200m)的变化最为明显.西太平洋暖池区的次表层冷暖信号明显早于西太平洋次表层的海温异常.分析发现,西太平洋暖池区的海温异常是导致整个西太平洋次表层海温场变异的关键区,当西太平洋暖池区的次表层冷暖信号加强时,3～4个月后西太平洋海温场出现大范围的冷暖异常.     

东太平洋地区DSDP573孔始新世末期的微玻璃陨石

通过研究 DSDP5 73孔的岩心样品 ,首次在该孔始新世与渐新世的界线地层含金属粘土层中发现了微玻璃陨石 ,且主要富集在其底部。一个样品 (5 g)中最多可达 12粒。这些微玻璃陨石主要呈球形、椭球形。用电子探针测试了其化学成分 ,Si O2 含量为 2 9.6 4%～ 5 8.93%,Al2 O3 为 3.42 %～ 2 0 .96 %,Fe O为 9.98%～ 2 9.5 5 %,Mg O为 4.32 %～ 16 .0 5 %,Ir为 0 .0 6 %～ 0 .81%。总体来说 ,微玻璃陨石的化学成分变化较大 ,可能与靶岩的成分变化较大有关。始新世末期北美微玻璃陨石场的展布方向约为 2 5 0°,这与太平洋板块运动方向改变所需要的矢量变化(2 45°)仅相差 5°,推测很可能是始新世末期陨星的撞击引起了太平洋板块在该时期的运动方向由 NNW突然变为NWW。     

大窑湾海域水化要素分布及相关关系的探讨

本文依据大窑湾的环境调查资料为基础，系统地阐述了水体中化学要素ｐＨ、盐度、透明度、ＤＯ、ＣＯＤ、ＴＯＣ、浊度、悬浮物、ＮＨ４－Ｎ、ＮＯ２－Ｎ、ＮＯ３－Ｎ、ＰＯ４－Ｐ、ＳｉＯ３－Ｓｉ、Ｃｕ、Ｐｂ、Ｚｎ、Ｃｄ、Ａｓ、Ｈｇ、Ｃｒ、硫化物、六六六、石油等分布规律。诸要素主要是在潮流水动力支配下，形成扩散带。各要素中仅有无机氮和ＰＯ４－Ｐ两项含量超标，其余要素含量范围都是处于海水正常浓度水平，属于一类海水水质。文章并对各要素进行相关关系分析。