摘要：This paper extends a prediction model for multi-directional random wave transformation based on an energy balance equation by Mase with the co.sideration of wave shoaling, refraction, diffraction, reflection and breaking. This numerical model is improved by 1) introducing Wen's frequency spectrum and Mitsuyasu's directional function, which are more suitable to the co.stal area of china; 2) co.sidering energy dissipation caused by bottom friction, which ensures more accurate results for large-scale and shallow water areas; 3) taking into acco.nt a non-linear dispersion relation. Predictions using the extended wave model are carried out to study the feasibility of co.structing the Ai Hua yacht port in Qingdao, china, with a co.parison between two port layouts in design. Wave fields inside the port for different incident wave directions, water levels and return periods are simulated, and then two kinds of parameters are calculated to evaluate the wave co.ditions for the two layouts. Analyses show that Layout I is better than Layout II. Calculation results also show that the harbor will be calm for different wave directions under the design water level. On the co.trary, the wave co.ditions do not wholly meet the requirements of a yacht port for ship berthing under the extreme water level. For safety co.sideration, the elevation of the breakwater might need to be properly increased to prevent wave overtopping under such water level. The extended numerical simulation model may provide an effective approach to co.puting wave heights in a harbor.

摘要：The plow of the submarine plowing trencher is one of the main functional mechanisms, and its optimization is very important. The design parameters play a very significant role in determining the requirements of the towing force of a vessel. A multi-objective genetic algorithm based on analytical models of the plow surface has been examined and applied in efforts to obtain optimal design of the plow. For a specific soil co.dition, the draft force and moldboard surface area which are the key parameters in the working process of the plow are optimized by finding the co.responding optimal values of the plow blade penetration angle and two surface angles of the main cutting blade of the plow. Parameters such as the moldboard side angle of deviation, moldboard lift angle, angular variation of the tangent line, and the spanning length are also analyzed with respect to the force of the moldboard surface along soil flow direction. Results show that the optimized plow has an improved plow performance. The draft forces of the main cutting blade and the moldboard are 10.6% and 7%, respectively, less than the original design. The standard deviation of Gaussian curvature of moldboard is lowered by 64.5%, which implies that the smoothness of the optimized moldboard surface is much greater than the original.

摘要：This paper addresses the need for systematic evaluation of the station keeping systems of deepwater drilling *** on the selected drilling semi-submersible co.figuration, the mooring systems were analyzed and designed for a range of water depths using different mooring line *** were steel wire rope, polyester rope and HMPE (high modulus poly ethylene).The mooring analysis was carried out using the advanced fully co.pled time domain analysis method in the co.puter software package *** analysis was first applied to solve the hydrodynamic properties of the vessel and then the motion equations of the co.plete dynamic system including the drilling rig, the mooring lines and risers were developed and solved in the time *** the advanced analysis method, a matrix of mooring systems was developed for operating in water depths of 1000 m, 1500 m, and 2 000 m using various mooring *** development of mooring systems was co.ducted in acco.dance with the co.monly adopted mooring design co.e, API RP 2SK and API RP *** attempts were then made to co.paratively evaluate the mooring system's characteristics and global *** results have been obtained in terms of mooring materials, water depths, and key parameters of mooring *** results provide in-depth insight for the design and operation of deepwater mooring systems in the South china Sea environment.

摘要：To overco.e the current difficulties of high-precision machining and the high manufacturing and maintenance co.ts of spherical seals for deep-water drilling ball joints,a new spherical seal technique is proposed in this *** spherical seal is mainly co.posed of silico.e rubber and polytetrafluoroethylene(PTFE).Rational structural design makes the seal independent from the ball and other co.ponents,making it easy to replace if leakage occurs at its *** can elastically deform over a certain deformation range,which guarantees that two sealing surfaces fit tightly together.O-Ring and PTFE elasticity makes up for any lack of accuracy during spherical machining and decreases the machining precision requirements for spherical *** a finite element technique and nonlinear theory,the performance of the spherical seal under the influence of various factors is *** results show that the spherical seal designed in this paper exhibits excellent sealing performance under lowtemperature and high-pressure *** spherical seal,a co.bination of an O-ring and PTFE,has the advantages of cheap manufacturing and maintenance co.ts and excellent sealing performance.

摘要：The demand for natural gas in the world is increasing day by day. The efficient and flexible LNG beco.es the preferred method for natural gas storage and transportation and has gradually entered people’s daily life. The enclosure system is the key co.e of LNG transport and storage vessels for storage of LNG at -163°C for isolation and thermal insulation. A new type of flat half-film prismatic LNG enclosure system has been developed for the shortco.ings of the existing LNG cargo enclosure system. Through the breakthrough and mastery of key co.e technologies such as the overall layout and integration of the system, anti-leakage technology, liquid tank fixing technology, and large-scale friction stir welding (P-FSW) flat-line pipeline development technology, we’ll strive to fill the gap in the intelligent co.struction technology of large aluminum alloy tanks in china. The tank was subjected to water vapor test and numerical simulation. The results show that the structural strength of the FSP-LNG tank meets the strength check standard of IGC co.e.

摘要：Attitude adjustment is a key link in the installation process of underwater facilities in deep *** solve this problem,an omnidirectional spirit level for deep water was *** sealing principle of the spirit level and the principle of deep-water pressure resistance are analyzed,and the threaded co.nection strength is *** mechanical simulation verifies that the spirit level can withstand the pressure of 2000 m water depth,and the water pressure test is carried out for 30 min in a 20 MPa hyperbaric *** the experiment is co.pleted,the appearance of the spirit level is intact and there is no *** experiment results show that the deep-water omnidirectional spirit level can be used in the deep sea within 2000 m.