Equivalent Simplifying of Tower Structure and Its Application in Overall Analysis of Offshore Platform

Based on some mechanical principles, this paper presents a new way for simplifying the tower structure on the platform, i. e., substituting the three-dimensional tower structure by using beam elements. For the overall analysis of offshore platform, this method can not only save man- power and computer time, but also get better results. This paper introduces the equivalent-simplifying method and its application in engineering.     

Experimental Research of Hexagon Multihole Armour Block on Breakwater

This paper introduces a new kind of armour block - hexagon multihole block on sloping breakwater. It has great characteristics such as good interlocking, strong resistance against waves and saving concrete. Through the hydraulic model test, the mechanism of stability of the block has been proved and the relations between stability and wave height, wave period, water depth, slope, laying method, porosity and cushion have been found. The effect of weight on steadiness have also been discovered. Finally, the method of design and some formulas are given.     

A Study on the Maneuvering Motion of a Low Speed Submersible

In this paper,the maneuvering characteristics of a low speed submersible are investigated.First,the captive model tests are carried out to obtain the hydrodynamic forces acting on the submersibleusing a Planar Motion Mechanism(PMM).For the hydrodynamic forces within a wide range of attack an-gles,the hydrodynamic coefficients which are usually used in the conventional maneuvering motion arequite difficult to be applied.In this case,a Fourier series is adopted to represent the hydrodynamic forcesand it fits the experimental data well.Then,based on the experimental results the simulation calculationsare made to predict some of the maneuvering performance of the low speed submersible.     

Local Joint Flexibility Multibrace Tubular Joints

The local joint flexibility matrix of multibrace tubular joints (uniplanar and multiplanar joints) is defined. The formulation for computing the elements of local flexibility factor matrix of multibrace tubular joints by semi- analytic method is presented in this paper. The stiffening effect of unloaded braces and cross-flexibility between braces are discussed. Using the local flexibility of unibrace joints instead of that of multibrace joints in conventional structural analysis will lead the result to an unsafe side.     

The Stress Concentration of Multiplanar Tubular Joints of Offshore Structure

- The formulation for the stress concentration matrix of multiplanar tubular joint with braces subjected to combined load is established in this paper. The formulations for SCF values of multiplanar tubular joints are compared with those by Wordsworth and Efthymiou. The stiffening effect and load-interaction effect are discussed. A spatial offshore jacket with braces subjected to combined load is computed as a numerical example. The maximum stress of each multiplanar tubular joint and its location are found through SCF matrix. Finally, the difference between the maximum stresses of multiplanar tubular joints and their corresponding uniplanar tubular joints are discussed.     

Experimental Research on Sewage Outfall Diffusers

The influence of diffuser parameters, including the riser spacing, port number in a riser, injection angle, port arrangement, etc., on the surface initial dilution is experimentally investigated. The relative density difference between the effluent and the sea water in the model is the same as that in the prototype, and the effect of the cross current is simulated by an inverse model technique. Based on the result analysis, the arrangement with more ports in a riser and larger riser spacing is suggested to save construction cost. The relationship between the Reynolds number based on the port diameter and velocity, and the surface initial dilution is also explored, and the critical Reynolds number is proposed.     

Estimation of JONSWAP Spectral Parameters by Using Measured Wave Data

- This paper presents the method of determining JONSWAP spectrum by using measured wave data. If Hs, Tz and Tc are the measured significant wave height, average zero-up crossing wave period and average period between wave crests respectively and let y = T Z / TC; this paper provides equation to solve y fromf(y,y) = 0. From the solutions of this equation and by using LSM, the expression relating y as a function of y (for 2.54相似文献   

珠江口盆地晚第四纪地层及环境初步研究

本文利用珠江口盆地四个工程钻井的古生物、古地磁、同位素及沉积物资料，对钻孔所揭露的地层进行划分，认为所钻遇的地层包括下更新统（上部）、中更新统、上更新统及全新统。依据古生物分异度及含量作出海平面变化曲线，识别出十个海侵期，利用钙质超微化石特征种的初现面和末现面资料，将本区海平面变化曲线与太平洋Ｖ＿（２８－２３９）氧同位素曲线对比，分析了本区晚第四纪以来的沉积环境和气候，认为早更新世晚期，中更新世中期，晚更新世早期及全新世本区气候温暖，沉积环境属陆架浅海环境。     

Seismic Response Reduction for Fixed Offshore Platform by Tuned Liquid Damper

An approach to seismic response reduction for offshore platforms by the use of the tuned liq-uid damper is presented in this paper.First of all,the effects of the tuned frequency ratio and excited fre-quency ratio on the seismic response reduction of the platform structure are investigated.Based on the re-sults,a mechanical model and equation of motion for the TLD-platform system are established.And theneffectiveness of the appraoch is verified by numerical calculation.     

Study on interaction between the coastal water, shelf water and Kuroshio water in the Huanghai Sea and East China Sea

The main processes of interaction between the coastal water, shelf water and Kuroshiowater in the Huanghai Sea (HS) and East China Sea (ECS) are analyzed based on the observation and study results in recent years. These processes include the intrusion of the Kuroshio water into the shelf area of the ECS, the entrainment of the shelf water into the Kuroshio, the seasonal process in the southern shelf area of the ECS controlled alternatively by the Taiwan Strait water and the Kuroshio water intruding into the shelf area, the interaction between the Kuroshio branch water, shelf mixed water and modified coastal water in the northeastern ECS, the water-exchange between the HS and ECS and the spread of the Changjiang diluted water.