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The main purpose of the article is to classify all the possible bursting oscillations in a vector field with Bogdanov–Takens bifurcation at the origin. Based on the universal unfolding of the normal form of the vector field, the topological structure in the neighborhood of the bifurcation point on the unfolding parameters is presented. Replacing one of the unfolding parameters by a slow-varying periodic exciting term, the coupling of two scales in frequency domain involves the vector field, which may lead to the bursting oscillations. According to the bifurcation analysis, we focus on three typical cases to investigate the dynamical evolution with the increase of the exciting amplitude. By introducing the transformed phase portrait, the mechanism of bursting oscillations can be presented. Three types of bifurcations, that is, fold, Hopf, and saddle on the limit cycle bifurcations may cause the alternations of the trajectory between the quiescent states and the spiking states, different combinations of which may result in different bursting attractors. Furthermore, the inertia of the movement may result in the delay effect of the bifurcation, which may lead to the disappearance of the bifurcation influence and the corresponding spiking oscillations. [ABSTRACT FROM AUTHOR]

In the present paper, complex bursting patterns caused by the coupling effect of different frequency scales in the Rayleigh–van der Pol–Duffing oscillator (RVDPDO) driven by the external excitation term are presented theoretically. Seven different kinds of bursting, i.e., bursting of compound “Homoclinic/Homoclinic” mode via “Homoclinic/Homoclinic” hysteresis loop, bursting of compound “fold/Homoclinic-Homoclinic/Hopf” mode via “fold/Homoclinic” hysteresis loop, bursting of compound “fold/Homoclinic-Hopf/Hopf” mode via “fold/Homoclinic” hysteresis loop, bursting of “fold/Homoclinic” mode via “fold/Homoclinic” hysteresis loop, bursting of “fold/Hopf” mode via “fold/fold” hysteresis loop, bursting of “Hopf/Hopf” mode via “fold/fold” hysteresis loop and bursting of “fold/fold” mode are studied by using the phase diagram, time domain signal analysis, phase portrait superposition analysis and slow-fast analysis. With the help of the Melnikov method, the parameter properties related to the beingness of the Homoclinic and Heteroclinic bifurcations chaos of the periodic excitations are investigated. Then, by acting the external forcing term as a slowly changing state variable, the stability and bifurcation characteristics of the generalized autonomous system are given, which performs a major part in the interpretative principles of different bursting patterns. This paper aims to show the sensitivity of dynamical characteristics of RVDPDO to the variation of parameter μ and decide how the choice of the parameters influences the manifold of RVDPDO during the repetitive spiking states. Finally, the validity of the research is tested and verified by the numerical simulations. [ABSTRACT FROM AUTHOR]

In this paper, we present a numeric bifurcation analysis of the normal form of degenerate Hopf bifurcation truncated up to seventh order with an equilibrium point located at the origin. By applying the genericity nondegenerate conditions and normal form theory, we study the bifurcation analysis of the codimension-3 Takens–Hopf bifurcation for the difficult case, where a rich bifurcation scenario is displayed. The third Lyapunov coefficient is used to distinguish the different cases of a codimension-3 Takens–Hopf bifurcation point, which can be efficiently computed with the aid of a software program based on the symbolic package Maple, presented in Appendix A. The normal form analysis results can be used to depict the complete bifurcation diagrams and phase portraits. In order to investigate the mechanism of the transitions between equilibrium and limit cycles, the methods of two scales in frequency domain are employed to study the evolutions. [ABSTRACT FROM AUTHOR]

The main purpose of this paper is to explore the bursting oscillations as well as the mechanism of a parametric and external excitation Filippov type system (PEEFS), in which different types of bursting oscillations such as fold/nonsmooth fold (NSF)/fold/NSF, fold/NSF/fold and fold/fold bursting oscillations can be observed. By employing the overlap of the transformed phase portrait and the equilibrium branches of the generalized autonomous system, the mechanisms of the bursting oscillations are investigated. Our results show that the fold bifurcation and the boundary equilibrium bifurcation (BEB) can cause the transitions between the quiescent states and repetitive spiking states. The oscillating frequencies of the spiking states can be approximated theoretically by their occurring mechanisms, which agree well with the numerical simulations. Furthermore, some nonsmooth evolutions are investigated by employing differential inclusions theory, which reveals that the positional relationship between the points of the trajectory interacting with the nonsmooth boundary and the related sliding boundary of the nonsmooth system may affect the nonsmooth evolutions. [ABSTRACT FROM AUTHOR]

The computation of the normal form as well as its unfolding is a key step to understand the topological structure of a bifurcation. Though a lot of results have been obtained, it still remains unsolved for higher co-dimensional bifurcations. The main purpose of this paper is devoted to the computation of a codimension-3 zero-Hopf–Hopf bifurcation, at which a zero as well as two pairs of pure imaginary eigenvalues can be found from the matrix evaluated at the equilibrium point. Different distributions of eigenvalues are considered, which may behave in a non-semisimple form for 1:1 internal resonance. Based on the combination of center manifold and normal form theory, all the coefficients of normal forms and nonlinear transformations are derived explicitly in terms of parameters of the original vector field, which are obtained via a recursive procedure. Accordingly, a user friendly computer program using a symbolic computation language Maple is developed to compute the coefficients up to an arbitrary order for a specific vector field with zero-Hopf–Hopf bifurcation. Furthermore, universal unfolding parameters are derived in terms of the perturbation of physical parameters, which can be employed to investigate the local behaviors in the neighborhood of the bifurcation point. Here, we emphasize that though different norm forms based on different choices may exist, their topological structures are the same, corresponding to qualitatively equivalent dynamics. [ABSTRACT FROM AUTHOR]

The mechanism of bursting oscillations in high dimensional systems with the coupling of two scales is an open problem in nonlinear dynamics, since there may coexist stable attractors in the fast subsystem with different bifurcations. Here we consider the bursting oscillations in the normal form up to the third order of a vector field with triple Hopf bifurcation at origin. When slow-varying external excitation is introduced, with the increase of the exciting amplitude, Hopf bifurcations in the three sub-planes occur in turn, which leads to three stable limit cycles. The dynamics may evolve from a 2-D torus bursting oscillations with two-mode and three-mode, respectively, the mechanism of which can be presented by overlapping the transformed phase portrait and the equilibrium states as well as the bifurcations of the fast subsystem. Synchronization and non-synchronization between the state variables in different sub-planes can be observed, which is explained by the bifurcations. An interesting phenomenon is found that the three-mode bursting oscillations still behave in quasi-periodic type instead of high dimensional torus. The projections of the trajectory in the sub-planes alternate between quiescence and repetitive spiking state with the oscillating frequency approximated at the frequency of the corresponding limit cycle. • Triple Hopf bifurcation may result in stable limit cycle in sub-planes. • Behavior evolves from single-mode to three-mode bursting attractor. • Synchronization and non-synchronization between the state variables appear. • Non-resonance leads to quasi-periodic bursting oscillations. • Delay effect may cause disappearance of influence of associated bifurcations. [ABSTRACT FROM AUTHOR]

The universal unfolding of a normal form can be employed to reveal the general behaviors of a specific local bifurcation, while the computation of the normal form for high codimensional bifurcation still remains unsolved. This paper focuses on a vector field with codimension-3 triple Hopf bifurcation. Besides 1:1 internal resonance for two frequencies in semi-simple form, two cases are considered, corresponding to internal resonance and noninternal resonance between the first two frequencies and the third frequency, respectively. Based on a combination of center manifold and normal theory, all the coefficients in the normal form and the nonlinear transformation are derived explicitly in terms of the coefficients of the original vector field. Upon the recursive procedure established, a user friendly computer program can be easily developed using a symbolic computation language Maple to compute the coefficients up to an arbitrary order for a specific vector field with triple Hopf bifurcation. Furthermore, universal unfolding of the normal form is obtained, which can be used to display the topological structure in the neighborhood of bifurcation point. It is pointed out that different choices of the remaining terms in the nonlinear transformation may lead to different expressions of the normal form and the unfolding, which are qualitatively equivalent to each other. [ABSTRACT FROM AUTHOR]

The pulse-shaped explosion (abbreviated as PSE) behavior, represented as the system roots pulse-shaped quantitative changing sharply, is a new way to the bursting oscillations proposed recently. In the present paper, the complex bursting oscillation patterns triggered by the PSE and integer frequency ratios are considered based on a Rayleigh–van der Pol system (abbreviated as RVDPS) excited by the parametrical and external forces. Two cascade bursting oscillations, the cascade supHopf/supHopf bursting oscillations induced by the integer frequency ratios and the cascade supHopf/supHopf bursting oscillations with multiple PSE/PSE hysteresis loops induced by the integer frequency ratios and PSEs, are investigated. We show that the PSEs occur when the system solution curve approaches to infinity at some certain values and the PSEs do not change the stabilities of the attractors. In addition, we find that the frequency and period of the cascade bursting oscillation patterns equal to that of the external force. Our study proposes a new PSE type to the bursting oscillations named the cascade PSEs and increases two cascade bursting oscillation patterns. [ABSTRACT FROM AUTHOR]

By introducing time-dependent power source, a periodically excited piecewise linear circuit with double-scroll is established. In the absence of the excitation, all possible equilibrium points as well as the stability conditions are presented. Analyzing the corresponding characteristic equations with perturbation method, Hopf bifurcation conditions associated with the equilibria are derived, which can be demonstrated by the numerical simulations. The Hopf bifurcations of the two symmetric equilibrium points may cause two symmetric periodic orbits, which lead to single-scroll chaotic attractors via sequences of period-doubling bifurcations with the variation of the parameters. The two chaotic attractors expand to interact with each other to form an enlarged chaotic attractor with double-scroll. The behaviors on the switching boundaries are investigated by the generalized Jacobian matrix. When periodic excitation is applied to work on the circuit, three periodic orbits with the frequency of the excitation may exist, which can be called generalized equilibrium points (GEPs) with the same characteristic polynomials as those of the corresponding equilibrium points for the autonomous case. It is shown that when the trajectories do not pass across the switching boundaries, the solutions are the same as the GEPs. However, when the trajectories pass across the switching boundaries, complicated behaviors will take place. Three forms of chaotic attractors via different bifurcations can be observed and the influence of the switching boundaries on the phase portraits is discussed to explore the mechanism of the dynamical evolution. [ABSTRACT FROM AUTHOR]

Abstract: A controlled Lorenz model with fast-slow effect has been established, in which there exist order gap between the variables associated with the controller and the original Lorenz oscillator, respectively. The conditions of fold bifurcation as well as Hopf bifurcation for the fast subsystem are derived to investigate the mechanism of the behaviors of the whole system. Two cases in which the equilibrium points of the fast subsystem behave in different characteristics have been considered, leading to different dynamical evolutions with the change of coupling strength. Several types of bursting phenomena, such as fold/fold burster, fold/Hopf burster, near-fold/Hopf burster, fold/near-Hopf buster have been observed. Theoretical analysis shows that the bifurcations points which connect the quiescent state and the repetitive spiking state agree well with the turning points of the trajectories of the bursters. Furthermore, the mechanism of the period-adding bifurcations, resulting in the rapid change of the period of the movements, is presented. [Copyright &y& Elsevier]

Abstract: In this paper we consider the Hirota transformation of the Caudrey–Dodd–Gibbon equation (CDGE) from another point of view. As a result, the local equivalence between the CDGE and its bilinear equation is established, and a new type of Bäcklund transformation, which is defined by a second-order ODE along with the appropriate initial values, is presented to construct new solutions for the bilinear CDGE from the seed solutions of original CDGE. [Copyright &y& Elsevier]

Abstract: In this Letter, we investigate the problem of impulsive synchronization of networked multi-agent systems, where each agent can be modeled as an identical nonlinear dynamical system. Firstly, an impulsive control protocol is designed for network with fixed topology based on the local information of agents. Then sufficient conditions are given to guarantee the synchronization of the networked nonlinear dynamical system by using algebraic graph theory and impulsive control theory. Furthermore, how to select the discrete instants and impulsive constants is discussed. The case that the topologies of the networks are switching is also considered. Numerical simulations show the effectiveness of our theoretical results. [Copyright &y& Elsevier]

Abstract: In this paper, the Fornberg–Whitham equation with linear dispersion term is investigated by employing the bifurcation method of dynamical systems. As a result, the existence of smooth and non-smooth traveling wave solutions is obtained. And the analytic expressions of solitary wave solutions, periodic cusp wave solutions and peakons are given under some parameter conditions. [Copyright &y& Elsevier]

Abstract: The dynamics of a non-smooth electric circuit with order gap between the natural frequency and the excitation frequency is investigated in this Letter. Different types of bursting phenomena can be observed in the numerical simulations. By assuming the forms of the solutions and introducing the generalized Jacobian matrix at the non-smooth boundaries, the bifurcation mechanism for the bursting solutions is presented, which can also be used to account for the evolution of the complicated structures of the phase portraits with the variation of the parameters. Period-adding bifurcation has been explored on the computation of the eigenvalues related to the solutions. It is shown that, the multiple crossing bifurcation, which is the combination of the Hopf bifurcation and the turning point bifurcation, occurring at the non-smooth boundaries leads the periodic burster to the quasi-periodic oscillation. [Copyright &y& Elsevier]

Abstract: In this Letter, adaptive projective synchronization (PS) between two complex networks with time-varying coupling delay is investigated by the adaptive control method, and this method has been applied to identify the exact topology of a weighted general complex network. To validate the proposed method, the Lü and Qi systems as the nodes of the networks are detailed analysis, and some numerical results show the effectiveness of the present method. [Copyright &y& Elsevier]

• Bursting oscillations of the vector field with a Double Hopf bifurcation are observed. • Bifurcation mechanism of bursting oscillations is presented. • Different forms of bursting oscillations with both single mode and mixed modes are obtained. Up to now, most of the work related to the slow-fast dynamical systems are based on the low dimensional systems with only codimension-one bifurcations at the transitions between the quiescent states and the spiking states, while there usually only exists one slow variable in the system. Since the coupling effect of two scales on the behaviors of high dimensional systems with two or more slow variables as well as high co-dimensional bifurcations lacks exploration, in this paper, we investigate the slow-fast effect on a 6-dimension system, which can be regarded as the coupling of two subsystems. The fast subsystem is expressed as the normal form of the vector field with a double Hopf bifurcation at the origin, while the slow-varying parameter in the fast subsystem is controlled by the slow subsystem. For the fast subsystem, the trajectory is projected onto two independent sub-planes for better observation, and the movement of bursting oscillators can be synthesized with information from each dimension. In the sub-plane, the mechanism of bursting oscillations is derived by employing the overlap of the transformed phase portrait and the equilibrium branches as well as the bifurcations. It is found that, Hopf bifurcation sets may cause the fast subsystem to transform between the single mode and the mixed-mode or between different single modes, leading to bursting oscillations in certain sub-planes or the whole four dimensions of the fast subsystem. Furthermore, interesting phenomena may be caught, such as the trajectory jumping in the process of oscillation as well as transforming between different oscillation modes of the fast subsystem by the way of jump as a result of the fold bifurcation set. [ABSTRACT FROM AUTHOR]

Abstract: The influence of initial phase difference as well as the amplitude of parametric excitation on the dynamics of a compound oscillator has been investigated in this paper. Based on the multiple time scale method, bifurcation sets of the averaged equations have been derived to divide the parameter space into regions associated with two types of phase trajectories. Imperfect cascading of period-doubling bifurcations have been observed, which may lead to different chaotic attractors. It is presented that, the three frequencies evolved in the vector field, though in resonance, may cause modulated effect on the structures of chaotic attractors. [Copyright &y& Elsevier]

Abstract: A new type of wave solutions, called as multiple-mode waves, which can be expressed in the superposition forms of more than two types of single-mode waves of Vakhnenko equation have been investigated in this Letter. A new general method for obtaining the multiple-mode waves is proposed, based on which four cases of the possible forms of wave solutions with two-mode have been derived. The explicit expressions of the two-mode waves as well as the existence conditions have been presented, which may be the nonlinear combinations between periodic waves, solitons, compactons, etc., with different wave speeds, respectively. It is pointed out that more complicated multiple-mode waves with more than three single-mode waves can be derived accordingly, which can be used to reveal the evolution of interactions between different types of waves, especially between various solitons. [Copyright &y& Elsevier]

Abstract: The dynamics of coupled Duffing''s oscillators with initial phase difference is investigated in this Letter. For the averaged equations, different equilibrium points can be observed, the number of which may vary with the parameters. The stable equilibrium points, corresponding to the periodic motion of the original coupled oscillators, may coexist with different patterns of dynamics, including chaos. Furthermore, two different chaotic attractors associated with different attracting basin coexist for certain parameter conditions, which may interact with each other to form an enlarged chaotic attractor. Several new dynamical phenomena such as boundary chaos crises have been predicted as the initial phase difference varies. [Copyright &y& Elsevier]

Abstract: The evolution of wave patterns of a generalized KdV equation is investigated in this Letter. For the topological vector filed, a singular line can be observed which separates the phase trajectories on the phase plane into two parts. All possible waves including compactons, solitary waves, smooth periodic waves and non-smooth periodic waves with peaks as well as the existence conditions have been presented. Specially, a new type of waves called as kink-compactons which combine both half structures of compacton and kink-wave can be found. [Copyright &y& Elsevier]

Abstract: The traveling waves of a generalized BBM equation with positive exponents have been investigated in this Letter. The influence of the parameters on the number as well as the characteristics of the equilibrium points have been discussed in detail. Qualitatively different kinds of phase portraits have been explored with the variations of the parameters. All the possible bounded waves have been obtained, including periodic waves, kink-waves and solitons. For the special parameter conditions, the exact explicit expressions of waves have been presented in the end. [Copyright &y& Elsevier]

Abstract: Different from what we have expected before, when a homoclinic orbit intersects with a quadratic singular curve on the topological phase plane derived from a generalized KdV equation, corresponding to the homoclinic orbit, there exist a few types of solitary waves, including peakons and antipeakons as well as periodic waves and furthermore, new types of solitary waves with peaks. The investigation shows that, when a trajectory along the homoclinic orbit moves at the intersection points between the homoclinic orbit and the singular curve, it may jump between these intersection points, which forms peaks on the waves, implying the nonsmooth solitary waves occur. [Copyright &y& Elsevier]

Abstract: The dynamics of a unidirectional non-linear wave equation which combines the linear dispersion of the Korteweg–de Vries (KdV) equation with the non-linear/non-local dispersion of the Camassa–Holm (CH) equation is explored in this Letter. Phase plane analysis is employed to investigate the bounded traveling-wave solutions. By considering the properties of the equilibrium points and the relative position of the singular line, transition boundaries have been derived to divide the parameter space into regions in which different types of phase trajectories can be observed. The explicit expressions of different types of solutions have been presented, which contain both the KdV solitons and the CH peakons as limiting cases. [Copyright &y& Elsevier]

The dynamical behavior of two coupled parametrically excited van der Pol oscillators is investigated in this paper. A special road to chaos is explored in detail. Period-doubling bifurcation associated with one of the frequencies of the system may be observed, the other frequency of the coupled oscillators plays a role in the evolution. It is found that one of the frequencies of the system contributes to the cascade of period-doubling bifurcations associated with the other frequency, which leads to a generalized modulated chaos. [ABSTRACT FROM AUTHOR]

The dynamical behavior of two coupled parametrically excited van der pol oscillators is investigated in this paper. Based on the averaged equations, the transition boundaries are sought to divide the parameter space into a set of regions, which correspond to different types of solutions. Two types of periodic solutions may bifurcate from the initial equilibrium. The periodic solutions may lose their stabilities via a generalized static bifurcation, which leads to stable quasi-periodic solutions, or via a generalized Hopf bifurcation, which leads to stable 3D tori. The instabilities of both the quasi-periodic solutions and the 3D tori may directly lead to chaos with the variation of the parameters. Two symmetric chaotic attractors are observed and for certain values of the parameters, the two attractors may interact with each other to form another enlarged chaotic attractor. [Copyright &y& Elsevier]

The main purpose of this paper is to study point-cycle type bistability as well as induced periodic bursting oscillations by taking a modified Filippov-type Chua's circuit system with a low-frequency external excitation as an example. Two different kinds of bistable structures in the fast subsystem are obtained via conventional bifurcation analyses; meanwhile, nonconventional bifurcations are also employed to explain the nonsmooth structures in the bistability. In the following numerical investigations, dynamic evolutions of the full system are presented by regarding the excitation amplitude and frequency as analysis parameters. As a consequence, we can find that the classification method for periodic bursting oscillations in smooth systems is not completely applicable when nonconventional bifurcations such as the sliding bifurcations and persistence bifurcation are involved; in addition, it should be pointed out that the emergence of the bursting oscillation does not completely depend on bifurcations under the point-cycle bistable structure in this paper. It is predicted that there may be other unrevealed slow–fast transition mechanisms worthy of further study. [ABSTRACT FROM AUTHOR]

This paper investigates the novel bursting patterns induced by different types of hysteresis loops in a parametrically and externally driven one-degree-of-freedom nonlinear oscillator (abbreviated as the PEDODOFNO) that can be represented the dynamics of a density perturbation in plasma device model. The bursting behavior named "fold/turning point-turning point/fold" form via "fold/turning point" hysteresis loop is investigated using the slow–fast analysis method in detail. Moreover, the dynamical transitions of the novel bursting, i.e., bursting of "fold/turning point-turning point/extreme point" form via "fold/turning point" hysteresis loop, bursting of "fold/fold-fold/extreme point" form via "fold/fold" hysteresis loop, bursting of "fold/fold-fold/extreme point-extreme point/turning point-turning point/fold" form via "fold/fold-extreme point/turning point" hysteresis loop, bursting of "fold/fold-fold/extreme point-extreme point/fold-fold/fold" form via "fold/fold-extreme point/fold" hysteresis loop, bursting of "fold/fold-fold/turning point-turning point/fold" form via "fold/fold" hysteresis loop, and bursting of "fold/fold" form via "fold/fold" hysteresis loop with a hypocritical cycle, are also studied. In these bursting patterns, the excited states are not the oscillations of the trajectory vibrating in the stable limit cycles conventionally, but the oscillations behaving in the hypocritical cycles that are produced by the procedures of the trajectory running steadily to the control range of the stable equilibria. The hypocritical cycles disappear by two approaches: the first is colliding with the saddle branches and the second is the control parameter reaching the maxima value. The two approaches result in the occurrence of the turning point and the extreme point, and then, the different types of hysteresis loops related to fold bifurcation, the turning point and the extreme point are created, which lead to the appearance of the distinctive hysteresis loops. [ABSTRACT FROM AUTHOR]

Slow-fast analysis has been extensively used in the past to study the occurrence of bursting oscillations. Most bursting oscillations studies are performed on the low dimensional autonomous systems where only codimension-1 bifurcations take place at the transitions of quiescent and spiking states. However, in high dimensional slow-fast dynamical systems, there exist higher co-dimensional bifurcations, which may lead to much more complicated mechanisms for bursting oscillations. To reveal and understand the complicated phenomena, the present paper investigates the normal form of a four-dimensional cubic order system with parametric excitation as a slow parameter. Parametric frequency is chosen far less than the natural frequencies to make sure the coupling of fast and slow scales. In the absence of parametric excitation, the system has a double Hopf bifurcation at the origin. Several equilibrium branches and mechanisms of bursting oscillations are obtained for different amplitudes of the parametric excitation. The trajectory of the system is projected onto two independent sub-planes, while the movement of bursting oscillators is synthesized by the properties in each sub-plane. In the sub-plane, the mechanism of bursting oscillations is derived by employing the overlap of the transformed phase portrait and the equilibrium branches as well as the bifurcations. The codimension-2 double Hopf bifurcation may result in the occurrence of the bursting oscillations in four dimensions. When the excitation amplitude is relatively small, the trajectory only follows the equilibrium branches of trivial and single-mode solutions. With the increase of the excitation amplitude, the trajectory switches between the equilibrium branches of single-mode and mixed-mode. Furthermore, a few interesting phenomena are presented. • Bursting oscillations of the vector field with a Double Hopf bifurcation are observed. • Bifurcation mechanism of bursting oscillations is presented. • Different forms of bursting oscillations with both single mode and mixed modes are obtained. [ABSTRACT FROM AUTHOR]

This paper aims to report the transient-chaos-induced chaotic bursting oscillations in a smooth three-dimensional dynamic model with a low-frequency excitation when an order gap exists between the excitation frequency and the natural frequency. Based on the Nosé-Hoover system, a periodically driven nonlinear system is modelled, in which the transient chaos induced by boundary crisis route can be observed. Through theoretical analysis and numerical simulation, the stability conditions of the equilibrium point and six transient-chaos-induced chaotic bifurcation structures are obtained. Six typical cases in which different routes of the trajectories pass through the transient chaos areas, leading to different patterns of bursting oscillations. It can be found that not only the bifurcation structures but also the bifurcation delay behavior can influence the bursting patterns. In addition, in the transient chaos areas, the bifurcation delay behavior can result in the disappearance of the periodic signals in the small periodic windows. • The transient chaos induced by the boundary crisis route can be observed. • Six different chaotic bifurcation structures can be observed. • Chaotic bursting oscillations are investigated by the modified fast/slow analysis method. • The sensitivity of system parameters on the dynamic evolutions is analyzed. [ABSTRACT FROM AUTHOR]

The using of an elliptical nozzle has been considered as a potential method for improving the air-fuel mixing and atomization quality. The present paper focuses on the transverse jet breakup behaviors and droplet size distribution for circular and elliptical orifices in supersonic crossflow on a pulse wind tunnel test platform, and the laser based pulsed laser background imaging method and high-speed spray particle size analyzer were adopted. The results show that the jet penetration depth of elliptical 4 (Aspect ratio of 4) orifice is always smaller than that of the circular orifice. Another interesting finding is that the difference of the jet penetration depth between the circular and elliptical 4 orifices decreases with the increase of injection pressure. Moreover, the jet surface wave number of the elliptical orifice is more than that of the circular jet, and the elliptical jet surface wave length is smaller than that of circular one. Additionally, the spray Sauter Mean Diameter (SMD) of elliptical 4 nozzle is 14.5% smaller than the circular spray at injection pressure of 5 MPa, and the elliptical 4 spray also has the smallest Dv50 and Dv90 among other orifices. Because elliptical 4 jet held larger windward surface area, which is helpful to increase the shear action of supersonic crossflow. Furthermore, the elliptical 4 spray produces the smallest droplet diameter at the largest volume fraction, and also the elliptical 4 spray has the smallest span of droplet diameter distribution than other orifices. • Transverse jet behaviors and droplet size were studied at supersonic crossflow. • The large windward area of elliptical jet resulted in short penetration depth. • The elliptical transverse jet has smaller SMD than that of circular jet. • The application of elliptical orifice improves mixing and atomization quality. [ABSTRACT FROM AUTHOR]

This paper focuses on the influence of two scales in the frequency domain on the behaviors of a typical dynamical system with a double Hopf bifurcation. By introducing an external periodic excitation to the normal form of the vector field with double Hopf bifurcation at the origin and taking the exciting frequency far less than the natural frequency, a theoretical model with two scales in the frequency domain is established. Regarding the whole exciting term as a slow-varying parameter leads to a generalized autonomous system, in which the equilibrium branches and their bifurcations with the variation of the slow-varying parameter can be derived. With the increase of the exciting amplitude, different types of bifurcations may be involved in the generalized autonomous system, resulting in several qualitatively different forms of bursting attractors, the mechanism of which is presented by overlapping the transformed phase portraits and the bifurcations of the equilibrium branches. It is found that the single mode 2D torus may evolve to the bursting attractors with mixed modes, in which the trajectory alternates between the single mode oscillations and the mixed mode oscillations. Furthermore, the transitions between the quiescent states and the spiking states may not occur exactly at the bifurcation points because of the slow passage effect, while Hopf bifurcations may cause different forms of repetitive spiking oscillations. [ABSTRACT FROM AUTHOR]

We study the slow–fast dynamics of a system with a double-Hopf bifurcation and a slowly varying parameter. The model consists of coupled Bonhöffer–van der Pol oscillators excited by a periodic slow-varying AC source. We consider two cases where the slowly varying parameter passes by or crosses the double-Hopf bifurcation, respectively. Due to the system's multistability, two bursting solutions are observed in each case: single-mode bursting and two-mode bursting. Further investigation reveals that the double-Hopf bifurcation causes a stable coexistence of these two bursting solutions. The mechanism of such coexistence is explained using the slowly changing phase portraits of the fast subsystem. We also show the robustness of the observed effect in the vicinity of the double-Hopf bifurcation. [ABSTRACT FROM AUTHOR]

The main purpose of the paper is to explore the influence of the coupling of two scales on the dynamics of a nonsmooth dynamical system. Based on a typical Chua's circuit, by introducing a nonlinear resistor with piecewise characteristics as well as a harmonically changed electric source, a modified nonsmooth model is established, in which the coupling of two scales in frequency domain exists. Different types of bursting oscillations, appearing in the combination of large-amplitude oscillations, called spiking oscillations (S P), and small-amplitude oscillations or at rest, denoted by quiescent states (Q S), can be observed with the variation of the exciting amplitude. When the exciting frequency is relatively small, by regarding the whole exciting term as a slow-varying parameter, the original system can be transformed into a generalized autonomous system. The phase space can be divided into three regions by the nonsmooth boundaries, in which the trajectory is governed by three different subsystems, respectively. Based on the analysis of the three subsystems as well as the behaviors on the nonsmooth boundaries, all the equilibrium branches and their bifurcations can be obtained, which can be employed to investigate the mechanism of the bursting oscillations. It is found that, for relatively small exciting amplitude, since no bifurcation on the equilibrium branches can be realized with the variation of the slow-varying parameter, the system behaves in periodic movement, which may evolve to bursting oscillations when a pair of fold bifurcations occurs with the increase of the exciting amplitude. Further increase of the exciting amplitude may lead to more complicated bursting oscillations, which may bifurcate into two coexisted asymmetric bursting attractors via symmetric breaking. Interaction between the two attractors may result in an enlarged symmetric bursting attractor, in which more forms of bifurcations at the transitions between the quiescent states and repetitive spiking states can be observed. [ABSTRACT FROM AUTHOR]

The main purpose of the paper is to explore the influence of the coupling of two scales on the dynamics of a nonsmooth dynamical system. Based on a typical Chua's circuit, by introducing a nonlinear resistor with piecewise characteristics as well as a harmonically changed electric source, a modified nonsmooth model is established, in which the coupling of two scales in frequency domain exists. Different types of bursting oscillations, appearing in the combination of large-amplitude oscillations, called spiking oscillations (S P), and small-amplitude oscillations or at rest, denoted by quiescent states (Q S), can be observed with the variation of the exciting amplitude. When the exciting frequency is relatively small, by regarding the whole exciting term as a slow-varying parameter, the original system can be transformed into a generalized autonomous system. The phase space can be divided into three regions by the nonsmooth boundaries, in which the trajectory is governed by three different subsystems, respectively. Based on the analysis of the three subsystems as well as the behaviors on the nonsmooth boundaries, all the equilibrium branches and their bifurcations can be obtained, which can be employed to investigate the mechanism of the bursting oscillations. It is found that, for relatively small exciting amplitude, since no bifurcation on the equilibrium branches can be realized with the variation of the slow-varying parameter, the system behaves in periodic movement, which may evolve to bursting oscillations when a pair of fold bifurcations occurs with the increase of the exciting amplitude. Further increase of the exciting amplitude may lead to more complicated bursting oscillations, which may bifurcate into two coexisted asymmetric bursting attractors via symmetric breaking. Interaction between the two attractors may result in an enlarged symmetric bursting attractor, in which more forms of bifurcations at the transitions between the quiescent states and repetitive spiking states can be observed. [ABSTRACT FROM AUTHOR]

Motivated by the forced harmonic vibration of complex mechanical systems, we analyze the dynamics involving different waves in a double-well potential oscillator coupling amplitude modulation control of low frequency. The combination of amplitude modulation factor significantly enriches the dynamical behaviors on the formation of multiple-S-shaped manifold and multiple jumping phenomena that alternate between epochs of slow and fast motion. We can conduct bifurcation analysis to identify two harmonic vibrations. One is that the singular orbit makes multiple jumps to a fast trajectory segment from one attracting equilibrium to another as the expression of slow variable by using the DeMoivre formula. With the increase of tuning frequency, the system exhibits relaxation-type oscillations whose small amplitude oscillations are produced by nonlinear local cycles together with a distinct large amplitude cycle oscillation accounting for the Melnikov threshold values. The tuning frequency may not only affect the asymptotic expressions for the solution curves near fold singularities but also allow for the large amplitude orbit vibrations near fold-cycle singularities. Numerical analysis for computing critical manifolds and their intersections is used to detect the dynamical features in this paper. [ABSTRACT FROM AUTHOR]