Elasto-Plastic Analysis of Tubular Joints of Offshore Platforms by Finite Element Method

The plastic node method is reformulated by the variational principle and is applied to elasto-plastic finite element analysis of tubular joints, eventually including the effect of internal and external gussets, stiffener rings, etc., if necessary. Four different joints are studied here in detail for the elasto-plastic behavior, the strain at the hot spot, the strain concentration factor around the intersection line, and the propagation of the plastic region with loading up to collapse in order to determine the ultimate strength, safety factor, and development of the plastic field. The present results are in good agreement with the experimental results.     

南海南部晚中新世的放射虫及其环境探讨

南海是东亚古季风产物的主要沉积盆地，保存着比陆地更加完整和连续的沉积记录。详细分析了ODP1143号钻井晚中新世的放射虫化石群，主要根据标志种Diartus petterssoni,D.hughesi和Stichocorys delmontensis等的分布特征，分别建立了南海南部晚中新世的RN6，RN7和RN8等3个放射虫化石带，并讨论了其地层年龄。探讨了以地层中放射虫的丰度变化特征等在南海南部作为东亚古夏季风活动替代性指标的可能性，初步说明东亚古夏季风可能早于8．7Ma B.P．出现，约在8．24Ma B.P.强化达到高峰，认为与印度季风的出现几乎同步或略早。     

Probabilistic Models for the Probability of Wave Breaking and Whitecap Coverage Based on Kinematic Breaking Criterion

More and more researches show that neither the critical downward acceleration nor the critical slope of water waves is a universal constant. On the contrary, they vary with particular wave conditions. This fact moders the models either for the probability of wave breaking B or for the whitecap coverage W based on these criteria difficult to apply. In this paper and the one which follows we seek to develop models for the prediction of both B and W based on the kinematical criterion. First, several joint probabihstic distribution functions (PDFs) of wave characteristics are derived, based on which the breaking properties B and W are estimated. The estimation is made on the assumption that a wave breaks ff the horizontal velocity of water particles at its crest exceeds the local wave celerity, and whitecapping occurs in regions of fluid where water particles travel faster than the waves. The consequent B and W depend on wave spectral moments of orders 0 to 4.Then the JONSWAP spectrum is used to represent the fetch-limited sea waves in deep water, so as to relate the probahility of wave breaking and the whitecap coverage with wind parameters. To this end, the time-averaging technique proposed by Glazman (1986) is applied to the estimation of the spectral moments involved, and furthermore, the theoretical models are compared with available observations collected from published literature. From the comparison, the averaging time scale is determined. The final models show that the probability of wave breaking as well as the whitecap coverage depends on the dimensionless fetch. The agreement between these models and the database is reasonable.     

Optimization Mathematical Model of Pile Forces for Offshore Piled Breasting Dolphins

An optimization mathematical model of the pile forces for piled breasting dolphins in the open sea under various loading conditions is presented. The optimum layout with the well distributed pile forces and the least number of piles is achieved by the multiplier penalty function method. Several engineering cases have been calculated and compared with the result of the conventional design method. It is shown that the number of piles can be reduced at least by 10%—20% and the piles‘ bearing state is improved greatly.     

Underice Operation of SJT-5 ROV

- The authors have used a low-cost ROV of observation type for underice surveying of the Nen-Jiang Cross-river oil pipe line in the Da Qing oil field. The operation method, process and the safety measures for severe cold areas are presented. The fruitful tries and experience may be useful to ROV operators in severe cold areas.     

A NUMERICAL MODEL FOR THE TIDES AND TIDAL CURRENTS IN THE TAIWAN STRAIT

Semidiurnal and diurnal tidal waves in the Taiwan Strait are computed simultaneously by using finite difference method with two-dimensional nonlinear hydrodynamic equations. The agreement between the computed and observed results is considered satisfactory.     

Regulation of Navigation Channel on Mouth Bar of Guanhe Estuary

-Based on the feasibility study of developing the navigation resources of the Guanhe River and the model test results of the mouth bar regulation, this paper presents some basic principles for the regulation of the channel on the mouth bar, for instance, the direction of navigation channel should be identical with that of the ebb tide current and the main waves, and perpendicular to the bathymetric contours. The principles for regulating mouth bars are also discussed in this paper.     

Variational iteration solving method for El Nio phenomenon atmospheric physics of nonlinear model

1 IntroductionThe El Ni’o atmospheric physics oscillation is anabnormal phenomenon involved in the tropical Pacificocean- atmosphere interactions. Studies on the El Ni(ophenomenon are very attractive (Lin et al., 2000; Linet al., 2001, 2002; Wang, 2001; Feng et al., 2001;Feng et al., 2002; Liu et al., 2002; Wei and Chen,2003; Xie et al., 2002; Zhu et al., 2002; Pu et al.,2003; Gu et al., 2004; Yu and Liu, 2004). Lin and Mo(2004), Mo and Lin (2004) and Mo et al. (2004) alsostudied a s…     

添加维生素B_（12）生产菌高密度培养褶皱臂尾轮虫的效果

阐述把维生素Ｂ１２生产菌添加到培养水中培养褶皱臂尾轮虫ＢｒａｃｈｉｏｎｕｓＰｌｉｃａｔｉｌｉｓ的买验。共１８株细菌分离于轮虫培养池，其中，有一株产维生素Ｂ１２的假单胞杆菌ＴＰ４对轮虫的生长繁殖有明显的促进作用。把ＴＰ４菌株培养后，加入到２Ｌ的烧杯和５００Ｌ的水槽中培养泰国Ｓ型轮虫时．在９ｄ（天）和６ｄ（天）中，轮虫密度从１２４～１３９和２４２～２８８个体／ｍｌ增殖到４，４１７～５，５４０和１，０１７～１，２５４个体／ｍｌ，分别比对照组增加了４～６及２～３倍。     

Refraction-Diffraction Mathematical Model for Waves With Lateral Energy Transmission Mechanism and Its Verification

To solve problems concerning wave elements and wave propagation, an effective way is the wave energy balance equation, which is widely applied in oceanography and ocean dynamics for its simple computation. The present papaer advances wave energy balance equations considering lateral energy transmission and energy loss as the governing equation for the study of wave refraction-diffraction. For the mathematical model, numerical simulation is made by means of difference method, and the result is verified with two examples.