The appropriate prediction of the hull deflection of a severely damaged warship is an important area in the research of the warship survivability. In this paper, the asymmetrical beam bending theory is applied to set up the damaged model, a comparison of the longitudinal strength, the deflections of damaged hull subjected to both hagging and sagging moments, and shear forces is carried out. The external loads are also calculated according to different damaged positions. Finally, some results and conclusions are obtained.
In this paper a 3-D panoramic simulation system of a ship is described which is developed with the MAXSCRIPT language and VC + + as programming tools on the platform of 3Dsmax. The strip theory method is applied to the motion prediction of the mono-hull. The time history solutions of heave and pitch are obtained in the condition of head sea to provide the primary data on panoramic simulation. The simulation system has following functions: 1) digital simulation; 2) panoramic simulation; 3) environmental set-up; 4) render preview and output.
The world trend in ship automation is to integrate the monitoring, intelligent control and systematic management of the instruments and equipments both on bridge and in engine room. The paper presents a design scheme of the ship integrated monitoring and operating system based on two layers distributed and redundant computer network. The lower layer network is the field bus network connected mainly by CAN bus; the upper one is the PC local network in TCP/IP protocol, which consisted of a database server, monitoring and operating computers, industrial computers and a set of switches. Distributed schemes are fully applied to both software and hardware. This paper specifically describes the composition, software distribution and redundant technology of the upper local network and gives some important sample codes for the implement of the redundant and distributed design. The technologies here have been proved in the many applications and it may be applied to other industrial fields.
In this paper, 3D track-keeping control method for autonomous underwater vehicle (AUV) with and without the influence of ocean current is investigated. Because the system to be controlled is highly nonlinear and strong coupled, an approach is used to divide it into two subsystems. One is to control the heading and the track error on the horizontal plane. The other is to control the pitch and the track error on the vertical plane. The results of computer simulation show that the autopilot works properly, it can capture the current waypoint and turns to track the next path automatically.
In order to reduce time and improve the probability of successful matting it is useful to co-ordinate between the movement control and mating process of the underwater vehicle. Because it is hard to control with the common method under the condition of mating process, the hierarchical intelligent control is introduced. Timed fuzzy Petri net (TFPN), which is the integration of PN and fuzzy reasoning, is used in the design of coordinate level of hierarchically intelligent control. It made the control process better in reflecting the characteristics of time-driven, event-driven, fuzzy information and so on. The test shows that TF-PN could shorten the time of mating and enhance the efficiency.
Having carried out investigations on ship collision accidents with bridges in waterway in China, a database of ship collision with bridge (SCB) is developed in this paper. It includes detailed information about more than 200 accidents near ship’s waterways in the last four decades, in which ships collided with the bridges. Based on the information a statistical analysis is presented tentatively. The increase in frequency of ship collision with bridges appears, and the accident quantity of the barge system is more than that of single ship. The main reason of all the factors for ship collision with bridge is the human errors, which takes up 70%. The quantity of the accidents happened during flooding period shows over 3 ∼ 6 times compared with the period from March to June in a year. The probability follows the normal distribution according to statistical analysis. Visibility, span between piers also have an effect on the frequency of the accidents.
The transformation of parallel translation can improve the smoothness of discrete series sometimes. In this paper, for ship pitch, a method to modify the system error is proposed via the transformation of parallel translation, which can give the optimize parameters using the Method of Minimum Squares. The series in the method can fit white exponential law better, and then be applied in GM(1,1) very well. The numerical experiments imply that the method is practical, which make the ship pitch system model more accurate than GM(1,1).
The rate of flow of the gas flowing through cirque chink often needs calculation in engineering. The characters of compressibility and thermodynamics have some effect on the gas flowing, so the analysis on the flow of gas is more complex than that of liquid. But under different conditions and different requirements of precision the analysis can be simplified suitably, then make the formulae given become simple subsequently. This paper analyzes various gas flux based on basic characters and motion laws of gas and the analysis is just applied in an engineering project.
A structure equivalent model of fuzzy-neural networks for system condition monitoring is proposed, whose outputs are the condition or the degree of fault occurring in some parts of the system. This network is composed of six layers of neurons, which represent the membership functions, fuzzy rules and outputs respectively. The structure parameters and weights are obtained by processing off-line learning, and the fuzzy rules are derived from the experience. The results of the computer simulation for the autonomous underwater vehicle condition monitoring based on this fuzzy-neural networks show that the network is efficient and feasible in gaining the condition information or the degree of fault of the two main propellers.
An Internet-based teleoperation platform for Mobile Robot is introduced in this paper. The hardware of the system mainly consists of a mobile robot. Its software employs client-server architecture for robot control and feedback information display. Different communication protocols are adopted according to the characteristics of message exchanged between the robot server and the client. The user interface is designed for the purpose of interaction. The great benefit of this client-server architecture is that the client software is insulated from the lowest level details of the mobile robot. Thus, it is very easy to implement and test new advanced teleoperation control algorithms, interface designs and applications on this platform without large programming work.
A mechanical system for quickfeeding shells in gunboat is particularly analyzed from a dynamic view. 3D nonlinear structural simulation is completed by means of dynamic explicit finite element method. Analysis results prove that the mechanical structure is feasible substantially, the material of outer surfaces near striking and overstress position should be improved and measures should be taken to avoid parts high temperature. And all analysis results give a principal theoretical basis for further work.
The medium — large caliber naval gun is still playing an important role in modern war. The development of highly automatic Shell Raising and Feeding System (SRFS) in the world has been briefly outlined. Several typical SRFS of medium-large caliber naval guns have been analyzed. A re-design of the system is introduced, in which systematic design method has been used to demonstrate its feasibility. The design goal of the system is to realize rapid shell feeding, with application to many types of shells, quick change of shell types, accurate and reliable feeding operation, simple mechanical structure and easy realization of shell withdrawing.
In this paper, a smart crank and slider mechanism is analyzed mostly from a dynamic view. By means of dynamic explicit finite element method, 3D nonlinear structure is simulated. It is proved that the mechanism can effectively accomplish smart movement prescribed. And in order to ensure reciprocal movement with higher frequency, measures should be taken to avoid over heating of parts. Compared with internal energy, kinetic energy of total rigid body is dominating, andY direction equivalent rigid velocity is much higher thanX direction velocity. Equivalent rigid velocity of all parts is consistent with respective movement condition. For both energy and velocity, slider effect is dominating. Three direction equivalent inertia force oscillates. Force amplitude inY-direction is comparitively the greatest.
A knowledge-based system in structural component design based on fracture mechanics is developed in this paper. The system consists of several functional parts: a general inference engine, a set of knowledge bases and data-bases, an interpretation engine, a bases administration system and the interface. It can simulate a human expert to make analysis and design scheme mainly for four kinds of typical structural components widely used in shipbuilding industry: pressure vessels, huge rotation constructions, pump-rod and welded structures. It is an open system which may be broadened and perfected to cover a wider range of engineering application through the modification and enlargement of knowledge bases and data-bases. It has a natural and friendly interface that may be easily operated. An on-line help service is also provided.
The paper presents the design of walking leg for bionics crab-like robot, which is driven with micro servo motor. The kinematic characteristics of the bionics machine are analysed for optimized structure parameters, which has been used in the robot design. A three closed loop motor control system structure for joint driver is also given, as well as the multi-joint driving system for walking robot leg.
A general solution of differential equation for transverse displacement function of orthotropic rectangular thin plates in free vibration is established in this paper. It can be used to solve the vibration problem of plate with arbitrary boundaries. As an example, the frequencies of a composite laminated plate with four free edges have been solved. The result as compared with the experiment is satisfactory.
The nanocrystalline γ - (Fe, Ni) alloy whiskers have been prepared by chemical reduction of Fe2+ and Ni2+ ions with potassium borohydride under the function of a dispersant agent PE followed by heat treatment at 600 °C under the protection of nitrogen. Conditions, such as quantity of NaOH, concentration of salts, and species of surfactants, of preparation of Fe - Ni alloy have been discussed. X-ray diffraction (XRD), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM) characterized the synthesized Fe-Ni alloy. Character, capability and use of the materials have been summarized.