In this paper, structural dynamic characteristics of a high-speed light special catamaran-wave piercing catamaran are analyzed using the FEA software MSC-NASTRAN. The dynamic reduction method is introduced to eliminate the local vibration modes in order to obtain the whole ship’s mode shapes. In the post-processor, a lot of accessorial methods are adopted to eliminate the local vibrations, so that the whole ship’s mode shapes can be identified. The modal analysis indicates that the dynamic reduction method fits for mode shapes identifying. In the end, the test results of a catamaran named Frederick G. Greed are used for reference to validate the obtained results. The comparison process shows that the results are credible. A special mode shape, which is quite different with that of conventional monohull ship, is also pointed out. The obtained results provide a valuable reference for the coming computation of catamaran’s vibration characteristics.

Because the general object of ship steering control system is singular, the state of rudder force and the state of disturbance are separated, and the generalized yaw output disturbance is obtained. Furthermore, singular system control problem of ship yaw and sway coupled system is transferred into nonsingular standard control problem. Then according to the linear fractional denoting algorithm of the rational function parameter perturbation system, the Linear Fractional Transform (LFT) model of yaw and sway coupled motion is solved, which is used to design the ship steering robust control system. For the ship steering system with the uncertain parameters, the robust control law is designed based on H^∞-synthesis. And the robust performance of the system is analyzed and the simulation validation is made. Simulation results show that the designed control system has excellent control effect and robustness.

Selecting optimization ship form scheme is an important content in the process of concept design of ship. Multi-objective fuzzy decision-making model for ship form demonstration is set up according to the fuzzy pattern-recognition theory. Weight coefficients of each target of ship form scheme are determined by information entropy and individual subjective partiality. This model is used to select the optimal ship form scheme, the example shows that the model is exact and the result is credible. It can provide a reference for choosing the optimization scheme of ship form.

The passive anti-rolling tank is one of important ship stabilizers widely used today. But at present, research of the tank is most aimed at its rolling movement. In this paper, the influence of sway motion on the passive anti-rolling tank is considered, the mathematical model of “ship-passive anti-rolling tank” system coupled with sway motion is developed basing on the U-shaped passive anti-rolling tank theory. Both simulation results and experimental data indicate that it is necesary to consider the influence of sway motion on the anti-rolling tank, which is more agreeble to the actual circumstance

The characteristics of the design resources in the ship collaborative design is described and the hierarchical model for the evaluation of the design resources is established. The comprehensive evaluation of the co-designers for the collaborative design resources has been done from different aspects using Analytic Hierarchy Process (AHP), and according to the evaluation results, the candidates are determined. Meanwhile, based on the principle of minimum cost, and starting fom the relations between the design tasks and the corresponding co-designers, the optimizing selection model of the collaborators is established and one novel genetic combined with simulated annealing algorithm is proposed to realize the optimization. It overcomes the defects of the genetic algorithm which may lead to the premature convergence and local optimization if used individually. Through the application of this method in the ship collaborative design system, it proves the feasibility and provides a quantitative method for the optimizing selection of the design resources.

This paper focuses on the process for pillow shape plate by line heating technique, which is widely applied in the production of ship hull. Based on the analysis of primary parameters and experimental data in the heating process, the amount of local contraction generated by line heating has been illustrated. Then, combining with the computational result of local deformation determined by shell plate development, an optimization method for line heating parameters has been studied. This prediction system may provide rational arrangements of heating lines and technical parameters of process. By integrating the prediction system into the line heating robot for pillow shape plate, the automatic process of line heating for pillow shape plate can be achieved

This paper proposes a new on-demand multi-alternate-path algorithm, called quickly switching routing algorithm (QSRA). It switches failure routing to an alternate path as quickly as the network can. Like a nervure shape, algorithm QSRA shapes disjoint-alternate-path structure, but is not limited to. It also contains another structure that every primary node has several links to alternate paths. This structure has two advantages, the first one is that primary nodes can select one alternate path immediately when primary routing is failure without going back to source node to re-discover a new routing or choose an alternate path; the second is that it guarantees primary nodes can select another alternate path as quickly as possible once one of alternate paths fails. Strongpoint of algorithm QSRA is reducing frequency of routing re-discovering. Besides, the structure occupies fewer resources than other routing algorithms due to its distributed structure. Simulation shows that QSRA has higher packets received ratio and lower control packet overhead and lower end-to-end delay.

Failure may occur catastrophically by fracture along grain boundaries when temper embrittlement induced by non-equilibrium, grain-boundary segregation (NGS) of phosphorus atoms. Temper embrittlement control technique based on the theory of NGS and deformation induced phase transformation in low-alloy steel, 12CrlMoV (which is used in steam pipeline of ships), was experimentally investigated. A single-pass hot rolling process by using a Gleeble-1500 system was performed, and the experimental results showed that the grain sizes were obviously affected by the deforming temperature, strains, strain rate and the quenching cooling rate. Temper embrittlement may be controlled and obviously improved by grain refinement.

This paper analyzes the motion state and forces of the warship gun breechblock cam. Firstly, the method of driven cam locking the breechblock safely and reliably can be obtained through analyzing the force between the driven cam and breechblock. And then according to the geometry and motion relationships between the driving cam, driven cam and stopper, the angular range of cams and the instataneous angular velocity of driven cam are obtained. Finally, with the specific velocity, the velocity-acceleration curve at the head of the driven cam can be obtained by simulating with the Adams software. It can ensure that the driven cam can make the part driven certain velocity in a short time and cannot deform plastically.

Based on experimental data of line heating, the methods of vector mapping, plane projection, and coordinate converting are presented to establish the spectra for line heating distortion discipline which shows the relationship between process parameters and distortion parameters of line heating. Back-propagation network (BP-net) is used to modify the spectra. Mathematical models for optimizing line heating techniques parameters, which include two-objective functions, are constructed. To convert the multi-objective optimization into a single-objective one, the method of changing weight coefficient is used, and then the individual fitness function is built up. Taking the number of heating lines, distance between the heating lines' border (line space), and shrink quantity of lines as three restrictive conditions, a hierarchy genetic algorithm (HGA) code is established by making use of information provided by the spectra, in which inner coding and outer coding adopt different heredity arithmetic operators in inherent operating. The numerical example shows that the spectra for line heating distortion discipline presented here can provide accurate information required by techniques parameter prediction of line heating process and the technique parameter optimization method based on HGA provided here can obtain good results for hull plate.

This paper has analyzed merits and demerits of both neural network technique and of the information fusion methods based on the D-S (dempster-shafer evidence) Theory as well as their complementarity, proposed the hierarchical information fusion fault diagnosis strategy by combining the neural network technique and the fused decision diagnosis based on D-S Theory, and established a corresponding functional model. Thus, we can not only solve a series of problems caused by rapid growth in size and complexity of neural network structure with diagnosis parameters increasing, but also can provide effective method for basic probability assignment in D-S Theory. The application of the strategy to diagnosing faults of motor bearings has proved that this method is of fairly high accuracy and reliability in fault diagnosis.