基因表达编程技术的180度弯曲浸没导向板附近腐蚀范围确定研究（英文）

Submerged vanes are installed on rivers and channel beds to protect the outer bank bends from scouring. Also, local scouring occurs around the submerged vanes over time, and identifying the effective factors on the scouring phenomena around these submerged vanes is one of the important issues in river engineering. The most important aim of this study is investigation of scour pattern around submerged vanes located in 180° bend experimentally and numerically. Firstly, the effects of various parameters such as the Froude number(Fr), angle of submerged vanes to the flow(α), angle of submerged vane location in the bend(θ),distance between submerged vanes(d), height(H), and length(L) of the vanes on the dimensionless volume of the scour hole were experimentally studied. The submerged vanes were installed on a 180° bend whose central radius and channel width were 2.8 and 0.6 m, respectively. By reducing the Froude number, the scour hole volume decreased. For all Froude numbers, the biggest scour hole formed at θ = 15°. In all models, by increasing the Froude number, the scour hole volume significantly increases. In addition, by increasing the submerged vanes' length and height, the scour hole dimensions also grow. Secondly,using gene expression programming(GEP), a relationship for determining the scour hole volume around the submerged vanes was provided. For this model, the determination coefficients(R~2) for the training and test modes were computed as 0.91 and 0.9,respectively. In addition, this study performed partial derivative sensitivity analysis(PDSA). According to the results, the PDSA was calculated as positive for all input variables.     

Experimental Research on Flash Boiling Spray of Dimethyl Ether

The high-speed digital imaging technique is applied to observe the developing process of flash boiling spray of dimethyl ether at low ambient pressure, and the effects of nozzle opening pressure and nozzle hole diameter on the spray shape, spray tip penetration and spray angle during the injection are investigated. The experimental results show that the time when the vortex ring structure of flash boiling spray forms and its developing process are determined by the combined action of the bubble growth and breakup in the spray and the air drag on the leading end of spray; with the enhancement of nozzle opening pressure, the spray tip penetration increases and the spray angle decreases. The influence of nozzle hole diameter on the spray tip penetration is relatively complicated, the spray tip penetration is longer with a smaller nozzle hole diameter at the early stage of injection, while the situation is just opposite at the later stage of injection. This paper establishes that the variation of spray angle is consistent with that of nozzle hole diameter.     

Wave load computation in direct strength analysis of semi-submersible platform structures

A wave load computation approach in direct strength analysis of semi-submersible platform structures was presented in this paper. Considering the differences in shape of pontoon, column and beam, the combination of accumulative chord length cubic parameter spline theory and analytic method was adopted for generating the wet surface mesh of platform. The hydrodynamic coefficients of platform were calculated by the three-dimensional potential flow theory of the linear hydrodynamic problem for platform with low forward speed. The equation of platform motions was established and solved in frequency domain, and the responses of wave-induced loads on the platform can be obtained. With the interpolation method being utilized, the pressure loads on shell elements for finite element analysis(FEA) were converted from those on the hydrodynamic computation mesh, which pave the basis for FEA with commercial software. A computer program based on this method has been developed ,and a calculation example of semi-submersible platform was illustrated. Analysis results show that this method is a satisfying approach of wave loads computation for this kind of platform.     

ABSTRACTS

FMC convenes Global Regulatory Summit with officials from China and European Commission
Maritime regulators from the United States, the People＇s Republic of China （PRC）, and the European Commission met and conferred in Washington, D.C. on December 17, 2013 to consider the evolving international maritime landscape. The officials had open and candid discussions on their differing regulatory frameworks and the potential effects of carrier cooperation on international trade. While most of the discussions were held privately by the regulators, FMC Chairman Mario Cordero and members of the delegations from China and Europe spoke briefly about their regulatory summit publicly at the end of the day. The summit was early on billed as a global regulatory summit on the P3 Alliance,     

Special requirements for alumina ceramic of ESG electrode bowl

At present ESG (Electrostatic Suspended Gyro) is the most precise inertia element in the world. The electrode bowl, which has direct effect on the precision of ESG, is a key part to ESG. Through the analysis of the function and characteristic of the electrode bowl in hollow rotor ESG and the present situation of new material development in the world, the alumina ceramic is regarded as the best material for the electrode bowl of hollow rotor ESG. By analyzing the present situation of alumina ceramic in the world, main technique requirements have been put forward for the alumina ceramic of ESG electrode bowl which is also fit for solid rotor ESG.     

冲压进水对空泡形态和空化器阻力特性的影响（英文）

Water ramjets using outer water as an oxidizer have been demonstrated as a potential propulsion mode for underwater High Speed Supercavitating Vehicles(HSSVs) because of their higher energy density, power density, and specific impulse, but water flux changes the shapes of supercavity. To uncover the cavitator drag characteristics and the supercavity shape of HSSVs with water inflow for ramjets, supercavitation flows around a disk cavitator with inlet hole are studied using the homogenous model. By changing the water inflow in the range of 0–10 L/s through cavitators having different water inlet areas, a series of numerical simulations of supercavitation flows was performed. The water inflow flux of ramjets significantly influences the drag features of disk cavitators and the supercavity shape, but it has little influence on the slender ratio of supercavitaty. Furthermore, as the water inlet area increases, the drag coefficient of the cavitators' front face decreases, but this increase does not influence the diameter of the supercavity's maximum cross section and the drag coefficient of the entire cavitator significantly. In addition, with increasing water flux of the ramjet, both the drag coefficient of cavitators and the maximum diameter of supercavities decrease stably. This research will be helpful for layout optimization and supercavitaty scheme design of HSSVs with water inflow for ramjets.     

侧推孔球状气泡逸出轨迹及振动初探(英文)

In an atrocious ocean environment,the lateral propulsion hole could potentially be partly out of water and capture an air cavity.Bubbles would form when the captured air cavity escapes underwater and they may affect the performance of the sonar.The common commercial computational fluid dynamics software CFX was adopted to calculate the ambient flow field around the lateral propulsion hole generated by a moving vessel.The oscillation of the spherical bubble was based on the Rayleigh-Plesset equation and its migration was modeled using the momentum equation.The radiated noise of the oscillating bubble was also studied.The aim is that the results from this paper would provide some insight into corresponding fluid and acoustic study.     

响应面法模拟轴肩和搅拌针形状对铝合金搅拌摩擦的影响(英文)

The present paper discusses the modeling of tool geometry effects on the friction stir aluminum welds using response surface methodology. The friction stir welding tools were designed with different shoulder and tool probe geometries based on a design matrix. The matrix for the tool designing was made for three types of tools, based on three types of probes, with three levels each for defining the shoulder surface type and probe profile geometries. Then, the effects of tool shoulder and probe geometries on friction stirred aluminum welds were experimentally investigated with respect to weld strength, weld cross section area, grain size of weld and grain size of thermo-mechanically affected zone. These effects were modeled using multiple and response surface regression analysis. The response surface regression modeling were found to be appropriate for defining the friction stir weldment characteristics.     

Comparison of robust H<Subscript>∞</Subscript> filter and Kalman filter for initial alignment of inertial navigation system

There are many filtering methods that can be used for the initial alignment of an integrated inertial navigation system. This paper discussed the use of GPS, but focused on two kinds of filters for the initial alignment of an integrated strapdown inertial navigation system （SINS）. One method is based on the Kalman filter （KF）, and the other is based on the robust filter. Simulation results showed that the filter provides a quick transient response and a little more accurate estimate than KF, given substantial process noise or unknown noise statistics. So the robust filter is an effective and useful method for initial alignment of SINS. This research should make the use of SINS more popular, and is also a step for further research.     

带吊舱水下机器人运动建模与仿真(英文)

To provide a simulation system platform for designing and debugging a small autonomous underwater vehicle’s (AUV) motion controller, a six-degree of freedom (6-DOF) dynamic model for AUV controlled by thruster and fins with appendages is examined. Based on the dynamic model, a simulation system for the AUV’s motion is established. The different kinds of typical motions are simulated to analyze the motion performance and the maneuverability of the AUV. In order to evaluate the influences of appendages on the motion performance of the AUV, simulations of the AUV with and without appendages are performed and compared. The results demonstrate the AUV has good maneuverability with and without appendages.     

Comparison of robust H∞ filter and Kalman filter for initial alignment of inertial navigation system

There are many filtering methods that can be used for the initial alignment of an integrated inertial navigation system. This paper discussed the use of GPS, but focused on two kinds of filters for the initial alignment of an integrated strapdown inertial navigation system (SINS). One method is based on the Kalman filter (KF), and the other is based on the robust filter. Simulation results showed that the filter provides a quick transient response and a little more accurate estimate than KF, given substantial process noise or unknown noise statistics. So the robust filter is an effective and useful method for initial alignment of SINS. This research should make the use of SINS more popular, and is also a step for further research.     

Local scour at submarine pipelines

The rapid development of offshore oilfields has increased the number of submarine pipelines being constructed for the transport of crude oil to onshore refineries.Interactions between the pipeline and an erodible bed under the influence of current and waves often lead to local scouring around the structure.When this occurs, the pipeline may be suspended on the seabed resulting in the formation of a span.If the free span is long enough, the pipe may experience resonant flow-induced oscillations,leading to structural failure.This study examines the complex flow-structure-sediment interaction leading to the development of local scour holes around submarine pipelines.It reviews published literature in this area,which primarily is confined to the development of 2- dimensional scour holes.Despite the abundance of such research studies,pipeline-scour in the field essentially is 3-dimensional in nature.Hence,most of these studies have overlooked the importance of the transverse dimension of the scour hole,while emphasizing on its vertical dimension.This clearly is an issue that must be re-examined in light of the potential hazard and environmental disaster that one faces in the event of a pipeline failure.Recent studies have begun to recognize this shortcoming,and attempts have been made to overcome the deficiency.The study presents the state-of-the-art knowledge on local scour at submarine pipelines,both from a 2-dimensional as well as the 3-dimensional perspective.     

Dynamic interaction of parallel moving ships in close proximity

Nowadays,there are many studies conducted in the field of marine hydrodynamics which focus on two vessels traveling and floating in sufficiently close proximity to experience significant interactions.The hydrodynamic behavior of parallel moving ships in waves is an interesting and important topic of late.A numerical investigation has been carried out for the prediction of wave exciting forces and motion responses of parallel moving ships in regular waves.The numerical solution was based on 3D distribution technique and using the linear wave theory to determine the exciting forces and ship＇s motion.The speed effects have been considered in the Green function for more realistic results.The numerical computations of wave exciting forces and motion responses were carried out for a Mariner and Series 60 for the purpose of discovering different Froude numbers and different separation distances in head sea conditions.Based on the numerical computations,it was revealed that the sway,roll and yaw have a significant effect due to hydrodynamic interaction.     

南海海底管道冲刷深度预测（英文）

Scour depth prediction of offshore pipelines is of great significance to the design and construction of the submarine pipeline projects. In this paper, based on the CFD software package FLUENT and User Defined Function(UDF), an Eulerian two-phase model, which includes an Euler-Euler coupled model for water and sediment phases, and a turbulent model for the fluid phase, is adopted to predict the scour depth around pipelines. The model is verified by observation data obtained from laboratory experiments. On the basis of the simulations, the factors affecting the scour depth, including the effects of incipient velocity, pipe diameter and sediment particle size and so on, were investigated. Meanwhile, according to formulas of incipient velocity of various sediments, approximate calculation on theoretical scour depths is developed for pipelines of seven stations in the South China Sea, where engineering application information is available.     

CFD simulation of the vertical motion characteristics of the moonpool fluid for the truss spar

The research purpose of this paper is to estimate theimpacts of the parameters of the guide plate on the vertical motioncharacteristics of the moonpool fluid. With the volume of fluid（VOF） method, three-dimensional models of the moonpool fluidmotions of the truss spar platform are established. Simulationresults are then presented for the moonpool forced oscillation byemploying the dynamic mesh method and user-defined functions inFLUENT. The motions of the moonpool fluid and the loads on theguide plates are obtained for both cases of square-ring andcrisscross. The results show that the shape and area of the guideplate at the bottom of the moonpool have a significant impact onthe physical parameters of the moonpool, including the load on themoonpool guide plate, motion form of the moonpool fluid and themass flow rate.     

Fully nonlinear simulation for fluid/structure impact: A review

This paper presents a review of the work on fluid/structure impact based on inviscid and imcompressible liquid and irrotational flow. The focus is on the velocity potential theory together with boundary element method （BEM）. Fully nonlinear boundary conditions are imposed on the unknown free surface and the wetted surface of the moving body. The review includes （1） vertical and oblique water entry of a body at constant or a prescribed varying speed, as well as free fall motion, （2） liquid droplets or column impact as well as wave impact on a body, （3） similarity solution of an expanding body. It covers two dimensional （2D）, axisymmetric and three dimensional （3D） cases. Key techniques used in the numerical simulation are outlined, including mesh generation on the multivalued free surface, the stretched coordinate system for expanding domain, the auxiliary function method for decoupling the mutual dependence of the pressure and the body motion, and treatment for the jet or the thin liquid film developed during impact.     

The 2007 work meeting of national waterborne transport

The 2007 work meeting of national waterborne transport was convened in Beijing on July 5, a date to be for ever remembered by the Chinese rivers, lakes and seas, for on this date waterborne transport was re-positioned and the clarion of marching toward a strong shipping country was blown. The sound swept across the rivers and lakes and surged over the col-orful shipping lines on the seas.     

基于混合迭代法的二维水翼空泡性能分析(英文)

In order to study cavitation characteristics of a 2-D hydrofoil, the method that combines nonlinear cavitation model and mixed-iteration is used to predict and analyze the cavitation performance of hydrofoils. The cavitation elements are nonlinearly disposed based on the Green formula and perturbation potential panel method. At the same time, the method that combines cavity shape for fixed cavity length (CSCL) iteration and cavity shape for fixed cavitation number (CSCN) iteration is used to work out the thickness and length of hydrofoil cavitations. Through analysis of calculation results, it can be concluded that the jump of pressure and velocity potentially exist between cavitation end area and non-cavitations area on suction surface when cavitation occurs on hydrofoil. In certain angles of attack, the cavitation number has a negative impact on the length of cavitations. And under the same angle of attack and cavitation number, the bigger the thickness of the hydrofoil, the shorter the cavitations length.     

斜浪下FLNG与LNGC旁靠时相对运动的时域分析（英文）

Strong hydrodynamic interactions during the side-by-side offloading operation between floating liquefied natural gas(FLNG) and liquefied natural gas carrier(LNGC) can induce high risks of collision. The weather vane effect of a single-point mooring system normally results in the satisfactory hydrodynamic performance of the side-by-side configuration in head seas. Nevertheless, the changes in wave directions in real sea conditions can significantly influence the relative motions. This article studies the relative motions of the side-by-side system by using the theoretical analysis method and the numerical calculation method. Based on the three-dimensional potential theory modified by artificial damping-lid method, the frequency-domain hydrodynamic coefficients can be improved to calculate the retardation functions for the multi-body problem. An in-house code is then developed to perform the time-domain simulation of two vessels, through which the relative motions are subsequently obtained. A range of oblique waves are chosen for the extensive calculation of relative motions between the two vessels, which are further analyzed in terms of the phase shift of motion responses induced by specific resonant wave patterns. Investigation results show that wave directions have a significant influence on the relative sway, roll, and yaw motions. Under the circumstance that the absolute phase shift between the roll motions of two vessels approaches 180°, stronger relative motions are induced when LNGC is on the weather side.Moreover, the gap water resonances at high frequencies tend to cause the dangerous opposed oscillation of two vessels in the sway and yaw modes, whereas FLNG reduces the gap water resonances and relative motions when located on the weather side.