近海污损生物的调查方法

近海海区污损生物调查有浮标挂板法和海上设施（浮标及其锚碇系统，Ｍａｒｅｘ水文浮标，移动式钻井平台和固定式生产平台）采样法。由于近海海区污损生物调查工作的特殊性和艰难性，笔者提出了利用已有的海上设施，尤其是固定式平台来积累近海污损生物资料，以便进行生态学研究。     

Structural monitoring of offshore platforms using impulse and relaxation response

Monitoring offshore platforms, long span bridges, high rise buildings, TV towers and other similar structures is essential for ensuring their safety in service. Continuous monitoring assumes even greater significance in the case of offshore platforms, which are highly susceptible to damage due to the corrosive environment and the continuous action of waves. Also, since a major part of the structure is under water and covered by marine growth, even a trained diver cannot easily detect damage in the structure. In the present work, vibration criterion is adopted for structural monitoring of jacket platforms. Artificial excitation of these structures is not always practicable and ambient excitation due to wind and waves may not be sufficient for collecting the required vibration data. Alternate methods can be adopted for the same purpose, for example, the application of an impact or a sudden relaxation of an applied force for exciting the structure. For jacket platforms, impact can be applied by gently pushing the structure at the fender while relaxation can be accomplished by pulling the structure and then suddenly releasing it using a tug or a supply vessel in both cases. The present study is an experimental investigation on a laboratory model of a jacket platform, for exploring the feasibility of adapting vibration responses due to impulse and relaxation, for structural monitoring. Effects of damage in six members of the platform as well as changes in deck masses were studied. A finite element model of the structure was used to analyze all the cases for comparison of the results as well as system identification. A data acquisition and analysis procedure for obtaining the response signatures of the platform due to the impulse and relaxation procedure was also developed for possible adoption in on-line monitoring of offshore platforms. From the study, it has been concluded that both impulse and relaxation responses are useful tools for monitoring offshore jacket platforms. The present work forms the basis for the development of an automated, on-line monitoring system for offshore platforms, using neural networks.     

世界海洋油气资源与勘探模式概述

描述了全球海洋油气储量的总体情况、海洋油气资源的地域分布以及海洋油气产量的状况与增长趋势。简略阐述了海洋油气勘探的阶段划分、海洋地质调查、海洋地球化学勘探、海洋非地震地球物理勘探以及海洋地震勘探各方法的基本特点、关键技术和常用手段等。对海洋油气勘探的前景,尤其是深水区和天然气水合物的勘探前景作了展望。     

波,流联合作用下的近岸海底沙波稳定性研究进展

近岸海底大型沙波是一种研究较为薄弱的地貌单元，但它的迁移对港口、航道和海底电缆及钻井平台、输油管道等海洋工程设施建设造成的危害极大。在综述目前国内外有关研究文献的基础上，概要地介绍了作者提出的一种较为简便、省力和有效的沙波迁移速率和沙波稳定性定量评价和预测方法，旨在提高航道通航能力和海洋工程建设的灾害防治和预测能力     

中国海洋地球物理进展

在中国地球物理学会50周年之际，总结海洋地球物理工作是十分重要的文章从中国海油气普查、近海工程地质调查。大洋多金属结核调查和中国海基础调查四个方面简要地阐述它们的进展。     

Improved assessments of wave-induced fatigue for free spanning pipelines

For subsea pipeline projects, the costs related to seabed correction and free span intervention are often considerable. Development of reliable methods for fatigue analyses of pipelines in free spans contributes to minimize costs without compromising pipeline integrity. Assessment of wave-induced fatigue damage on multi-span pipelines is investigated, and improved analysis methods are suggested in this paper. A time-domain (TD) algorithm is developed, which accounts for non-linear hydrodynamic loading and dynamic interaction between adjacent spans. The proposed TD approach is employed to evaluate linearized frequency-domain (FD) solutions from recognized design standards and to study the dynamic response of multi-span pipelines to direct wave loading. Differences between multi- and single-span analyses are described for the first time, and the common assumption that the main fatigue damage contribution comes from the fundamental mode is demonstrated not to hold for multi-spans. An improved FD solution capable of predicting multi-mode response is derived and demonstrated to give accurate fatigue life estimates for multi-span pipelines.     

Information structuring and risk-based inspection for the marine oil pipelines

The proposed work is incorporated into the research theme concerning the maintenance and inspection of sensitive facilities in production systems. It is essential to promote the methodological deployment of inspection techniques to ensure the good functioning of services provided by complex production systems as well as their different components. We use a risk-based inspection methodology offering an organized analysis with knowledge sharing for collaborative possibilities in a multidisciplinary context and it consists of the following steps: data acquisition and information collection, failure analysis (probability and consequences), risk assessment, inspection plan, mitigation and revaluation. The application of this methodology can improve the maintenance management strategies of industrial companies. The inspection department is able to forecast its potential failure, root causes and impacts on the safe operation of the considered production system, based on a reliable inventory of existing situations and review options for continuous improvement in maintenance management. In particular, we addressed the application of a Risk-Based Inspection (RBI) methodology in the French petroleum company with operations on the west coast of central and southern Africa. The incorporation of expert knowledge into risk assessment is helping to find the best preventive plan for pipeline inspection in the case study.     

An improved two-step soil-structure interaction modeling method for dynamical analyses of offshore wind turbines

The detailed modeling of soil-structure interaction is often neglected in simulation codes for offshore wind energy converters. This has several causes: On the one hand, soil models are in general sophisticated and have many degrees of freedom. On the other hand, for very stiff foundations the effect of soil-structure interaction could often be discounted. Therefore, very simple approaches are utilized or the whole structure is assumed to be clamped at the seabed. To improve the consideration of soil-structure interaction, a six-directional, coupled, linear approach is proposed, which contains an implementation of soil-structure interaction matrices in the system matrices of the whole substructure. The aero-hydro-servo-elastic simulation code FAST has been modified for this purpose. Subsequently, a 5 MW offshore wind energy converter with pile foundation is regarded in two examples.     

Uncertainty analysis of soil-pile interactions of monopile offshore wind turbine support structures

The objective of this work is to study the uncertainties involved in the modelling of the soil-pile interaction concerning their influence on the prediction of the dynamic structural response of monopile offshore wind turbine support structures. Two main issues are identified and addressed: the adequacy of the method used to deal with the soil-pile interactions and the adequacy of the soil properties reflecting the behaviour of the soil. The present study develops an approach that defines the penetrated pile length depending on the soil profile. Also, a parameter is defined to avoid the excessive usage of steel for the penetrated pile structure. The uncertainties are included in the probabilistic free vibration analysis and the contribution of each random variable to the scatter of the response is estimated by performing a sensitivity analysis. The results indicate that the uncertainty involved in the modelling of the soil profile has a significant effect on the coefficient of variance of the natural frequency, which is a serious issue to be considered in the fatigue life assessment of offshore wind turbine support structures.     

Dynamic modeling and vibration suppression for an offshore wind turbine with a tuned mass damper in floating platform

The worldwide demand for renewable energy is increasing rapidly. Wind energy appears as a good solution to copy with the energy shortage situation. In recent years, offshore wind energy has become an attractive option due to the increasing development of the multitudinous offshore wind turbines. Because of the unstable vibration for the barge-type offshore wind turbine in various maritime conditions, an ameliorative method incorporating a tuned mass damper (TMD) in offshore wind turbine platform is proposed to demonstrate the improvement of the structural dynamic performance in this investigation. The Lagrange's equations are applied to establish a limited degree-of-freedom (DOF) mathematical model for the barge-type offshore wind turbine. The objective function is defined as the suppression rate of the standard deviation for the tower top deflection due to the fact that the tower top deflection is essential to the tower bottom fatigue loads, then frequency tuning method and genetic algorithm (GA) are employed respectively to obtain the globally optimum TMD design parameters using this objective function. Numerical simulations based on FAST have been carried out in typical load cases in order to evaluate the effect of the passive control system. The need to prevent the platform mass increasing obviously has become apparent due to the installation of a heavy TMD in the barge-type platform. In this case, partial ballast is substituted for the equal mass of the tuned mass damper, and then the vibration mitigation is simulated in five typical load cases. The results show that the passive control can improve the dynamic responses of the barge-type wind turbine by placing a TMD in the floating platform. Through replacing partial ballast with a uniform mass of the tuned mass damper, a significant reduction of the dynamic response is also observed in simulation results for the barge-type floating structure.