摘要：A three-dimensional method of calculating wave loads of turret moored FPSO (Flo ating Production Storage and Offloading) tankers is presented. The linearized restoring forces acting on the ship hull by the mooring system are calculated according to the catenary theory, which are expressed as the function of linear stiffness coefficients and the displacements of the upper ends of mooring chains. The hydrodynamic coefficients of the ship are calculated by the three-dimensional potential flow theory of the linear hydrodynamic problem for ships with a low forward speed. The equations of ship motions are established with the effect of the restoring forces from the mooring system included as linear stiffness coefficients. The equations of motions are solved in frequency domain, and the responses of wave-induced motions and loads on the ship can be obtained. A computer pro gram based on this method has been developed,and some calculation examples are illustrated. Analysis results show that the method can give satisfying prediction of wave loads.

摘要：For the purpose of achieving high-resolution optimal solutions this paper proposes a nodal design variablebased adaptive method for topology optimization of continuum structures. The analysis mesh-independent density field, interpolated by the nodal design variables at a given set of density points, is adaptively refined/coarsened accord- ing to a criterion regarding the gray-scale measure of local regions. New density points are added into the gray regions and redundant ones are removed from the regions occupied by purely solid/void phases for decreasing the number of de- sign variables. A penalization factor adaptivity technique is employed-to prevent premature convergence of the optimiza- tion iterations. Such an adaptive scheme not only improves the structural boundary description quality, but also allows for sufficient further topological evolution of the structural layout in higher adaptivity levels and thus essentially enables high-resolution solutions. Moreover, compared with the case with uniformly and finely distributed density points, the proposed adaptive method can achieve a higher numerical efficiency of the optimization process.

摘要：In this paper, a 3D source distribution technique is used to calculate the coupled motions between two ships which advance in the wave with the same speed. The numerical results of coupled motions for a frigate and a supply ship have a good agreement with the experimental results. Based on the 3D coupled motions of two ships, a spectral analysis is employed to clearly observe the effect of speed, clearance and wave heading on the significant relative motion amplitude (SRMA) of two ships. The method presented in this paper will be helpful to select suitable clearance, speed and wave heading for underway replenishment at sea(RAS).

摘要：Purpose–Micro aerial vehicle is nonlinear plant;it is difficult to obtain stable control for MAV attitude due to *** purpose of this paper is to propose one robust stable control strategy for MAV to accommodate system uncertainties,variations,and external ***/methodology/approach–First,by employing interval type-II fuzzy neural network(ITIIFNN)to approximate the nonlinearity function and uncertainty functions in the attitude angle dynamic model of micro aircraft vehicle(MAV).Then,the Lyapunov stability theorem is used to testify the asymptotic stability of the closed-loop system,the parameters of the ITIIFNN and gain of sliding mode control can be tuned on-line by adaptive laws based on Lyapunov synthesis approach,and the Lyapunov stability theorem has been used to testify the asymptotic stability of the closed-loop ***–The validity of the proposed control method has been verified through real-time *** experimental results show that the performance of interval type-II fuzzy neural network based gain adaptive sliding mode controller(GASMC-ITIIFNN)is significantly improved compared with conventional adaptive sliding mode controller(CASMC),type-I fuzzy neural network based sliding mode controller(GASMC-TIFNN).Practical implications–This approach has been used in one MAV,the controller works well,and which could guarantee the MAV control system with good performances under uncertainties,variations,and external ***/value–The main original contributions of this paper are:the proposed control scheme makes full use of the nominal model of the MAV attitude control model;the overall closed-loop control system is globally stable demonstrated by Lyapunov stable theory;the tracking error can be asymptotically attenuated to a desired small level around zero by appropriate chosen parameters and learning rates;and the MAV attitude control system based on GASMC-ITIIFNN controller can achieve favourable tracki

摘要：Experimental tests were conducted to evaluate the hydrodynamic performance of an L-type podded propulsor in straight-ahead motion and off-design conditions using an open-water measuring instrument developed by the authors for podded propulsors, a ship model towing tank, and under water particle image velocimetry （PIV） measurement systems. Under the three types of conditions, the main parameters of an L-type podded propulsor were measured, including the propeller thrust and torque, as well as the thrust, side force, and moment of the whole pod *** addition, the flow field on the section between the propeller and the strut was analyzed. Experimental results demonstrate that the dynamic azimuthing rate and direction and the turning direction affect the forces on the propeller and the whole pod unit. Forces are asymmetrically distributed between the left and right azimuthing directions because of the effect of propeller rotation. The findings of this study provide a foundation for further research on L-type podded propulsors.

摘要：In this paper,the mechatronic design and maneuverability analysis of a novel robotic shark are *** obtain good maneuverability,a barycenter regulating device is designed to assist the posture adjustment at low *** on the Newton-Euler approach,an analytical dynamic model is established with particular consideration of pectoral fins for threedimensional *** hydrodynamic coefficients are computed using computational fluid dynamics(CFD)*** amplitudes and phases are determined by fitting an optimized fish body *** performance of the robotic shark is estimated by varying the oscillation frequency and offset *** results show that with oscillation frequency increasing,the swimming speed increases *** robotic shark reaches the maximum swimming speed of 1.05 m/s with an oscillation frequency of 1.2 ***,the turning radius decreases nonlinearly as the offset angle *** robotic shark reaches the minimum turning radius of 1.4 times the body length with 0.2 Hz frequency and 12°offset *** the vertical plane,as the pectoral fin angle increases,the diving velocity increases nonlinearly with increase rate slowing down.

摘要：In order to understand the influence of bow shape on ice resistance and provide guidelines for hull line design in the early design stage,an investigation of the impact of bow shape on ice resistance for the Arctic LNG carriers is carried out based on semi-empirical ***,some typical semi-empirical formulas developed for ice resistance estimation of cargo carriers in different ice conditions are ***,formulas appropriate for ice resistance estimation of Arctic LNG carriers under different ice conditions are verified according to the result comparison between semi-empirical formulas and experimental *** comparison result indicates that the Lindqvist formula is appropriate for ice resistance estimation in level ice conditions,Zuev and Dobrodeev formula for ice resistance estimation in broken ice conditions,and Dobrodeev formula for ice resistance estimation in brash ice *** that,the parameters considered in the selected formulas are summarized,and the influence of critical parameters on ice resistance is *** parameters describing the ship's bow shape characteristic like ship breadth,waterline angle and stem angle greatly influence the ice *** resistance increases with both the growth of ship breadth under all ice conditions and the growth of stem angle in level ice and broken ice conditions while ice resistance decreases with the development of waterline angle under all ice ***,the optimization of the bow shape is discussed,and an optimized bow shape with both a large waterline angle and low stem angle is *** optimized bow shape can decrease ice resistance by 9.9%in the level ice condition and reduce ice resistance by 11.3%in the brash ice condition.

摘要：In-situ exploration of asteroid surfaces is of great scientific *** actuated rovers have been released to asteroid surfaces but without enough *** investigate the attitude control characteristics of the cubic rover for asteroid surface exploration,a series of experiments are carried out using the self-designed rover and the low-gravity *** experiments focus on two major themes:The minimum flywheel speed for cubic rover to produce a walking motion in different conditions,and the relationship between the rover’s rotation angle and the flywheel speed in twisting *** rover’s dynamical descriptions of the walking and twisting motions are first *** features and design of the low-gravity testbed are then summarized,including its dynamics,setup,and validation.A detailed comparison between the dynamic model and the experimental results is presented,which provides a basic reference of the cubic rover’s attitude control in low-gravity environments.

摘要：When an oceanographic vessel is sailing, the currents near the surface of ship hull are rapid, making it hard to meet the environmental requirements of scientific observation equipment. To guarantee the installation space and environmental requirements of the observation equipment, the drop keel system was proposed for the first time for ocean-graphic ships at China, to avoid the traditional ＂rudder-shaft＂ type fin keel＇s disadvantage. The research study will examine the operational mechanism and functions of the drop keel system, the operating conditions of the fin keel to determine the driver method and its arrangement, and the locking method of the fin keel underwater. The research wilI also provide some general designs for analyzing the best plan for the drop keel system.

摘要：When using traditional game methods to study information security of the wireless sensor networks,players are mostly based on the assumption of completely *** on bounded rationality,the evolutionary game theory is used to establish the attack-defense model,analyze the strategy selection process of players,solve the evolutionarily stable strategy and design the optimal strategy selection ***,considering the strategy dependence,the incentive and punishment mechanism is introduced to improve the replicator dynamic *** simulation results show that the model is reasonable and the algorithm is effective,which provides new theoretical support for the security of wireless sensor networks.