Jin Hongzhang

Research on a Method to Reduce Ship Roll at Zero Speed

Most ships which need roll stabilization at zero speed have to select anti-roll tank to reduce ship roll because fin stabilizer can not reduce ship roll at zero speed. As the anti-roll technology develops, a kind of anti-roll system based on Weis-Fogh mechanism theory can reduce roll at zero speed. The working way and the lift of the anti-roll system has been studied. This paper analyzes the lift of the anti-roll system using hydrodynamics of the Weis-Fogh mechanism, builds a lift model of the anti-roll system at zero speed. The simulation is done base on the lift model. From the simulating results, it can be seen that the anti-roll system based on Weis-Fogh mechanism can generate lift when the anti-roll system works in special way at zero speed

The research on brittle catastrophe of complex giant system

The research on open complex giant system has been done in this paper, in which brittleness as one of the basic characteristics is presented on the basis of the traits of its collapse. Analysis on the small sample events have been carried out about the system under the disturbance from the inside and outside based on information diffusion theory considering that the system has the brittleness. Moreover, brittle potential function has been induced applying the distribution function of random depending on catastrophe theory after the collectivity probability density has been got. Finally, brittleness link function is defined, which can serve the further quantitative research on optimizing open complex giant system.

Brittleness in Electric Transmission Network

Brittleness in electric power transmission network is the cascading failure of electric power transmission network. When brittleness is motivated, large blackouts in electric transmission networks appear. In order to avoid this serious event, exploring the reason, the process and the condition of brittleness are more important. From data of large blackouts in the past years, sum up the reason and the representative process of the brittleness in electric transmission networks. Analyze the brittleness of electric transmission networks by using brittle theory and build the two-dimension brittle model by progressive sand-pile model be known as self-organized criticality (SOC) theory. Through simulation, we know that brittleness being motivated is the process of cascading collapse. Two conditions of brittleness being motivated, that is, the loading degree of the most lines is 1 and disturbance value is sufficient large

Research on basic characteristics of complex system brittleness

The goal of this paper is to research one new characteristic of complex system. Brittleness, which is one new characteritic of complex system, is presented in this paper. The linguistic and qualitative descriptions of complex system are also given in this paper. Otherwise, the qualitative description of complex system is presented at first. On the basis of analyzing the existing brittleness problems, linguistic description and mathematic description of brittleness are given as well. Three kinds of phenomena to judge brittleness of complex system are also given, based on catastrophe theory. Basic characteristics of brittleness are given on the basis of its mathematic description. Two critical point sets are defined by using catastrophe theory. The definition of brittleness and its related theory can serve the control of complex system, and provide theoretical basis for the design and control of complex system.

Robust sliding mode control for a class of uncertain nonlinear singularly perturbed systems

This paper is concerned with the problem of robust sliding mode control for a strongly nonlinear 3-DOF ship motion model,which has three time scales and can be cast in a singularly perturbed form. Based on a smooth version of sliding mode control,a new approach of the robust controller design for the system is proposed,which handles the uncertainties. The capabilities of the proposed controller is verified by the simulation results of the system of lift feedback fin stabilizer.

Prediction of Stabilization of Ship in Random Wave

In this paper we show the method of energy in part with which we can get the model of random wave, and predict the roll motion of unstabilized ship and stabilized ship using the wave model. The control parameters of fin stabilizer are determined according to the performance index. The simulation of the system is also made in this paper. The comparison of the simulation with real ship indicates that the method can be used in the prediction of roll motion of a stabilized ship in random wave.

Study on complex system based on the brittleness

The research on the basic characteristics of complex system has been done in this paper, in which brittleness as one of them is presented. Meanwhile, according to the theory of set pairing, concepts of brittle link function, brittle link entropy and basic element are defined. Finally, on the basis of data from the country from April to May, taking Beijing, and Neimenggu as examples, analysis have been carried out on the severe acute respiratory syndrome (SARS) based on the theory of brittleness. The results of simulation show that brittle entropy increase and brittle entropy of subsystems tend to ascend at the beginning of SARS interference. After subsystems obtain the negative entropy from the environment, the entropy will be decreased. Effective methods are the key factor of controlling the spread of SARS.

Research on a fuzzy immune PID controller to reduce roll of near-water-surface vehicle with active bionic fin stabilizer

Near-surface vehicel will invectively roll, pitch and heave heavily when they close to surface where there are waves, sea wind and ocean current. These disturbances influenced the normal working and safety of the autonomous underwater vehicles a lot. As anti-roll technology develops, a kind of active bionic fin stabilizer which can reduce roll effectively comes out. Hence this kind of active stabilization system has a lot of uncertainties, A fuzzy-immune PID controller is proposed to optimize parameters of PID controller under different wave disturbance. From simulation results, it can be seen that this kind of PID controller can optimize system effectively.

Variable structure control based on grey prediction for ship fin stabilizer

Ship fin stabilizer is widely employed in reducing rolling motion. But the effectiveness of ship fin stabilizer can be severely deteriorated due to the nonlinear and uncertainty arising from ship parameter variations, unsteady hydrodynamic characteristics, and waves. Variable structure control can offer several desirable characteristics, such as fast dynamic response, insensitivity to parameter variations, and rejection to external disturbances. However, common variable structure controllers require not only the bound value of uncertainty be known in advance but also the existence of chattering, especially to discrete system. The grey prediction method requires only a few sampled data to develop the grey model and to forecast on future. In this paper, an improved reaching law and an improved grey prediction method are employed to enhance performance and reduce chattering.

Research on the influence of action between fin and anti-rolling tank on the integrated stabilization effect

Through analyzing the roll model of the integrated system of fin and anti-rolling tank, this paper uses binomial equation to simplify the module and check how the approximate parameters simulate the original function. Based on the simplified module, the influence of fin and anti-rolling tank on the coefficient items of the roll module is discussed, and the influencing factors between fin and anti-rolling tank are analysed. And through simulation, the influence of action between fin and anti-rolling tank on the static characteristics, and the integrated stabilization effect, are analyzed.