ANTI-SYNCHRONIZATION OF TWO TIME-DELAY BIDIRECTIONAL COUPLING HYPERCHAOTIC SYSTEMS VIA NONLINEAR CONTROL

In this paper we study the chaos synchronization and anti-synchronization problems between two hyper-chaotic systems with bidirectional coupling,and present synchronization and anti-synchronization methods of chaotic systems,based on timedelayed feedback.Coupling coefficients between the drive and response systems are different,which are supposed to be nonlinearly coupled.Based on the nonlinear control theory,the synchronization and anti-synchronization between two different time-delay hyper-chaotic systems are investigated.The condition of synchronization is derived according to the error dynamical systems.Numerical simulations show the effectiveness and feasibility of the proposed synchronous conditions.

Some synchronization criteria for bidirectionally-coupled chaotic systems

Based on the stability theory of linear time-varying continuous system, this paper investigates the synchronization of two linear bidirectionally-coupled systems. Sufficient conditions for asymptotic synchronization are obtained for general chaotic system with bidirectional coupling via linear error feedback. Since the trajectory of chaotic system is continuous and bounded, one can choose suitable coupled pararneters to satisfy the proposed criterion. The criterion can also be applied to the global synchronization for chaotic systems with linear unidirectional coupling. The chaotic Chen system and the generalized Lorenz-like system are taken as examples, the simulations verify the effectiveness of the proposed method.

Outer synchronization between two different fractional-order general complex dynamical networks

Outer synchronization between two different fractional-order general complex dynamical networks is investigated in this paper. Based on the stability theory of the fractional-order system, the sufficient criteria for outer synchronization are derived analytically by applying the nonlinear control and the bidirectional coupling methods. The proposed synchronization method is applicable to almost all kinds of coupled fractional-order general complex dynamical networks. Neither a symmetric nor irreducible coupling configuration matrix is required. In addition, no constraint is imposed on the inner-coupling matrix. Numerical examples are also provided to demonstrate the validity of the presented synchronization scheme. Numeric evidence shows that both the feedback strength k and the fractional order a can be chosen appropriately to adjust the synchronization effect effectively.

Transient Analysis of a Reactor Coolant Pump Rotor Seizure Nuclear Accident

The reactor coolant pump(RCP)rotor seizure accident is defined as a short-time seizure of the RCP rotor.This event typically leads to an abrupt flow decrease in the corresponding loop and an ensuing reactor and turbine trip.The significant reduction of core coolant flow while the reactor is being operated at full load can have very negative consequences.This potentially dangerous event is typically characterized by a complex transient behavior in terms of flow conditions and energy transformation,which need to be analyzed and understood.This study constructed transient flow and rotational speed mathematical models under various degrees of rotor seizure using the test data collected from a dedicated transient rotor seizure test system.Then,bidirectional fluid-solid coupling simulations were conducted to investigate the flow evolution mechanism.It is found that the influence of the impeller structure size and transient braking acceleration on the unsteady head(Hu)is dominant in rotor seizure accident events.Moreover,the present results also show that the rotational acceleration additional head(Hu1)is much higher than the instantaneous head(Hu2).

The changes on synchronizing ability of coupled networks from ring networks to chain networks

In this paper, two different ring networks with unidirectional couplings and with bidirectional couplings were discussed by theoretical analysis. It was found that the effects on synchronizing ability of the two different structures by cutting a link are completely opposite. The synchronizing ability will decrease if the change is from bidirectional ring to bidirectional chain. Moreover, the change on synchronizing ability will be four times if the number of N is large enough. However, it will increase obviously from unidirectional ring to unidirectional chain. It will be N^2/（π^2） times if the number of N is large enough. The numerical simulations confirm the conclusion in quality. This paper also discusses the effects on synchronization by adding one link with different length d to these two different structures. It can be seen that the effects are different. Theoretical results are accordant to numerical simulations. Synchronization is an essential physics problem. These results proposed in this paper have some important reference meanings on the real world networks, such as the bioecological system networks, the designing of the circuit, etc.

Numerical investigation on failure behavior of steel plate under explosive loading

The failure behavior of metal materials under strong dynamic loading such as explosive and impact loading has important applications in the fields of defense industry and civil security. In this study, a novel coupled bidirectional weighted mapping method between Lagrange particles and Euler meshes is proposed to numerically simulate the dynamic response and failure process of steel structure under explosive loading. In this method, the Lagrange particles and Euler meshes are used to describe the materials that need to be accurately tracked and can more accurately characterize the deformation history and failure process of the material. A comparison between the numerical results and experimental data shows that this method can be used to solve large deformation problem of multi-medium materials and the failure problems of complex structures under strong impact loading.