An Engineering Computational Method of Calculating Wave Forces on the Mat and Platform''''s Sit-on-Bottom Stability

- In this paper, an engineering method is employed to calculate the horizontal and vertical wave forces on the mat of the submersible platform under Froude-Krylov hypothesis. According to some model tests, appropriate diffraction coefficients are selected. And the results of the formulae given in the paper agree satisfactorily with those experimental data now available. The proposed computational method is effective and convenient to use in evaluating the horizontal and vertical wave forces on the mat. An exmaple is also given in this paper. Finally, the effects of the vertical wave force on the platorm's sit-on-bottom stability are analyzed.     

Finite Element Method for Design of Reinforced Concrete Offshore Platforms

A design method of reinforced concrete (R. C.) offshore platforms with nonlinear finite element analysis is proposed. According to the method, a computer program is developed. In this program nonlinear constitutive relationships and strength criteria of concrete and steel bars are included, and the progressive cracking and crushing of the concrete are taken into account. Based on the stress distribution obtained by the nonlinear finite element analysis, the amount of reinforcement in the control sections can be computed and adjusted automatically by the program to satisfy the requirement of the design. The amount of reinforcement required in the control sections, which are obtained with the nonlinear finite element analysis, is agreeable to that obtained in the experiment. This shows that the design method of R. C. offshore platform with the nonlinear finite element method proposed by the authors is reliable for practical use.     

Technical foundation research on high resolution remote sensing system of China''s coastal zone

China‘s coastal zone is a region with a highly developed economy that contrasts clearly with the slow paced regular investigation on its natural environment, which cannot keep pace with the requirement of economic development and modem management.Laying a theoretical foundation for the modem management of China‘s costal zone is aimed at.This research focuses on the following processing and analyzing technologies for coastal zone high-resolution remote sensing data: organization and management of large amounts of high-resolution remote sensing data, quick and precise spatial positioning system,algorithms for image fusion in feature level and coastal zone feature extraction. They will form a technical foundation of the system. And, if combined with other research results such as coastal zone remote sensing classification system and its mapping subsystem, an advanced technical frame for remote sensing investigation of coastal zone resource will be constructed.     

罗非鱼椭圆囊电生理学研究

罗非鱼球状囊微音器电位是一个双峰波。峰频与刺激声频成２：１关系；在２０－８０Ｈｚ电位波形不规则。在３００－９００Ｈｚ电位波呈矩形。实验表明，球状囊不同区域对一一的声频敏感性不一样；延脑－脊髓连结处的诱发电位与球状囊微音器电位相似，但在１３０Ｈｚ电位呈单峰波；罗非鱼可闻频域在２０－９００Ｈｚ，最大敏感声频在１３０Ｈｚ，其相对敏感性为２３．０１ｄＢ；延脑－脊髓连接处诱发电位最大值在６３Ｈｚ和１３０Ｈｚ     

Suppression of Wave-Excited Vibration of Offshore Platform by Use of Tuned Liquid Dampers

This paper describes experimenlal and theoretical investigations of Tuned Liquid Damper (TLD) characteristics tor suppressing the wave-excited structural vibration. The structural model lor the experiments is scaled according to a full size offshore platform by matching their dynamic properties. Rectangular TLDs of different sizes with partially filled liquid are examined. By observing the performance and behavior of TLDs through laboratory experiments, the study investigates the influence of a number of parameters, including container size, container shape, frequency ratio, and incident wave characteristics. In an analytical study, a mathematical model that describes the nonlinear behavior of liquid in TLD and the interaction of TLD and structure is prerequisite. The validity of the model is evaluated and simulating results can reasonably match the corresponding experimental results.     

基于风浪联合概率模型的海洋平台结构系统可靠度分析

基于多变量极值理论的联合概率模型,根据BZ28—1油田一年多的风浪同步观测资料统计得到风浪联合概率分布及其参数,讨论了海洋平台结构系统可靠度分析的等效荷载方法,在此基础上分析了JZ20—2MUQ平台结构的系统可靠度,并与不考虑风浪相关性影响的JZ20—2MUQ平台结构的系统可靠度比较,得到了风浪相关性对系统可靠度的影响情况。     

楚科奇海与白令海表层沉积中的钙质和硅质微体化石研究

通过对北冰洋楚科奇海和令海41个表层沉积样品中的有孔虫、介形类等钙质微体化石和硅藻、放射虫、海绵骨针等硅质微体化石的定量分析，发现表层沉积中浮游有孔虫几乎缺失，这可能与该区表层生产力相对低、碳酸盐溶解作用较强有关，而底栖有孔虫和硅质微体化石的丰度分布则明显受表层沉积物类型、表层初级生物生产力和碳酸盐溶解作用所控制。其中，北冰洋楚科奇海陆架区有孔虫丰度和分异度低，含少量浅水介形类，放射虫在陆架浅水区缺失，但含有较多硅藻和海绵骨针等其它硅质微体化石，反映该区由于海冰、表层海水温度较冷而导致表歧初级生产力相对低。白令海陆坡区底栖有孔虫丰度比较科奇海高一个数量级，底栖有孔虫分异度也相对高，硅藻、放射虫、海绵骨针等硅质微体化石的丰度与钙质化石一样，其丰度比楚科奇海明显高，反映表层初级生产力相对高。根据白令海陆坡区底栖有孔虫和硅质微体化石丰度、底栖有孔虫胶结质壳比值的水深变化，推测该区碳酸盐溶跃层和补偿深度（CCD）相对浅，分别位于水深2000m和3800m处。     

中太平洋海盆碳酸钙溶解带及其特征

本文通过对不同水深区沉积物中组分、生物面貌、矿物、ＣａＣＯ３含量和碳酸钙溶解率等特征的分析和对比，把本区碳酸钙溶解深度带划分为碳酸钙溶跃面（小于３７００ｍ）、弱溶带（３７００～４８００ｍ）、强溶带（４８００～５２００ｍ）和全溶带（大于５２００ｍ）。提出本海域碳酸钙补偿深度界面约在５２００ｍ。文中还阐述了不同碳酸钙溶解带及其沉积物特征，认为造成这种特征的主要原因是随着水深变化碳酸钙溶解程度不同以及与南极底层流等因素的影响有关。     

基于重点抽样法的固定式平台结构风险评价研究

在建立海上油气设施的风险分析系统时,对由台风引发的极端海况造成的结构失效进行风险评估是1个十分重要的问题。为了建立实用可靠的风险评价方法,本文使用基于重点抽样法的随机模拟技术,对渤海海域CB12-C井组平台结构进行了全概率法失效概率计算,并在此基础上进行了平台结构的风险评价。该方法是1种适用于固定式海洋平台的定量风险评价方法,充分考虑了平台结构风险分析过程中各种不确定性的影响,极大提高了定量风险评价结果的可靠性。     

Multilevel Optimal Design of Prestressed Lightweight Concrete-Steel Platform Structures

The concrete-steel platform structure is rather complicated because it involves such materials as concrete, reinforcing bars, steel, and so on. K the traditional dimension optimization method is employed, the optimal design of the platform will meet many handicaps, even it cannot be implemented at all. The multilevel optimal design approach is an efficient tool for the solution of large-scale engineering structures. In this paper, this approach is applied to the optimal design of a concrete-steel platform, which is formulated as a system level optimal design problem and a set of uncoupled substructure level optimal design problems. The process of optimization is a process of iteration between system level and substructure level until the objective function converges. An illustrative example indicates that this method is effective in the optimal design of concrete-steel platforms.