Periodic orbits and chaos around two black holes

1990 ◽  
Vol 431 (1881) ◽  
pp. 183-202 ◽  
Keyword(s):  
Black Holes ◽  
Periodic Orbits ◽  
Initial Conditions ◽  
Classical Problem ◽  
Period Doubling ◽  
Satellite Orbits ◽  
Unstable Periodic Orbits ◽  
Newtonian Case ◽  
Stable Periodic ◽  
Escaping Orbits

We calculate orbits of photons and particles in the relativistic problem of two extreme Reissner-Nordström black holes (fixed). In the case of photons there are three types of non-periodic orbits, namely orbits falling into the black holes M 1 and M 2 (types I and II), and orbits escaping to infinity (III). The various types of orbits are separated by orbits asymptotic to the three main types of (unstable) periodic orbits: ( a ) around M 1 , ( b ) around M 2 and ( c ) around both M 1 and M 2 . Between two non-periodic orbits of two different types there are orbits of the third type. The initial conditions of the three types of orbits form three Cantor sets, and this fact is a manifestation of chaos. The role of higher-order periodic orbits is explained. In the case of particles the situation is similar in the parabolic and hyperbolic cases. However, in the elliptic case the orbits are contained inside a curve of zero velocity, and there are no escaping orbits. Instead we have orbits trapped around stable periodic orbits (IV) and stochastic orbits not falling on the black holes M 1 and M 2 (V). The stable periodic orbits become unstable by period doubling, and infinite period doublings lead to chaos. The newtonian limit is an integrable problem (essentially the same as the classical problem of two fixed centres). The periodic orbits of type ( c ) are topologically similar to the corresponding relativistic orbits, but they differ considerably numerically. We prove that in the newtonian case there are no satellite orbits around M 1 or M 2 (of type ( a ) or ( b )). The post-newtonian case is non-integrable. In this case there are in general orbits of all three types ( a ), ( b ) and ( c ).

Periodic orbits and chaos around two fixed black holes. II

1991 ◽  
Vol 435 (1895) ◽  
pp. 551-562 ◽  
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Periodic Orbits ◽  
Satellite Orbits ◽  
Unstable Periodic Orbits ◽  
Zero Velocity ◽  
Stable Periodic

We study the orbits of particles (time-like geodesics) around two fixed black holes when the energy is elliptic, i. e. it does not allow the motion to extend to infinity. Most orbits are chaotic, but in many cases there are also ordered motions around stable periodic orbits. The orbits that fall into the first or the second black hole are separated by unstable periodic orbits. These are the satellite periodic orbits around the black holes when they exist. But for certain intervals of parameters there are no satellite orbits around the first or the second black hole. Then the limiting orbits are like arcs of hyperbolae, reaching the curve of zero velocity.

scholarly journals THE STRUCTURE AND EVOLUTION OF CONFINED TORI NEAR A HAMILTONIAN HOPF BIFURCATION

2011 ◽  
Vol 21 (08) ◽  
pp. 2321-2330 ◽  
Author(s):  
M. KATSANIKAS ◽  
P. A. PATSIS ◽  
G. CONTOPOULOS
Keyword(s):  
Hopf Bifurcation ◽  
Periodic Orbits ◽  
Transition Point ◽  
Initial Conditions ◽  
Unstable Periodic Orbits ◽  
Unstable Periodic Orbit ◽  
Surface Of Section ◽  
Autonomous Hamiltonian System ◽  
Hamiltonian Hopf Bifurcation ◽  
Stable Periodic

We study the orbital behavior at the neighborhood of complex unstable periodic orbits in a 3D autonomous Hamiltonian system of galactic type. At a transition of a family of periodic orbits from stability to complex instability (also known as Hamiltonian Hopf Bifurcation) the four eigenvalues of the stable periodic orbits move out of the unit circle. Then the periodic orbits become complex unstable. In this paper, we first integrate initial conditions close to the ones of a complex unstable periodic orbit, which is close to the transition point. Then, we plot the consequents of the corresponding orbit in a 4D surface of section. To visualize this surface of section we use the method of color and rotation [Patsis & Zachilas, 1994]. We find that the consequents are contained in 2D "confined tori". Then, we investigate the structure of the phase space in the neighborhood of complex unstable periodic orbits, which are further away from the transition point. In these cases we observe clouds of points in the 4D surfaces of section. The transition between the two types of orbital behavior is abrupt.

Calculation of stable and unstable periodic orbits in a chopper-fed DC drive

2020 ◽  
Vol 8 (1) ◽  
pp. 43-57
Author(s):  
O. O. Kuznyetsov ◽  
Keyword(s):  
Periodic Orbits ◽  
Chaotic Behavior ◽  
Period Doubling ◽  
Nonlinear Phenomena ◽  
Unstable Periodic Orbits ◽  
Border Collision Bifurcations ◽  
Stable Periodic ◽  
Main Period ◽  
Dc Drive ◽  
The Stability

It is well known that electric drives demonstrate various nonlinear phenomena. In particular, a chopper-fed analog DC drive system is characterized by the route to chaotic behavior though period-doubling cascade. Besides, the considered system demonstrates coexistence of several stable periodic modes within the stability boundaries of the main period-1 orbit. We discover the evolution of several periodic orbits utilizing the semi-analytical method based on the Filippov theory for the stability analysis of periodic orbits. We analyze, in particular, stable and unstable period-1, 2, 3 and 4 orbits, as well as independent on stability they are significant for the organization of phase space. We demonstrate, in particular, that the unstable periodic orbits undergo border collision bifurcations; those occur according to several scenarios related to the interaction of different orbits of the same period, including persistence border collision, when a periodic orbit is changed by a different orbit of the same period, and birth or disappearance of a couple of orbits of the same period characterized by different topology.

scholarly journals A Bifurcation Analysis and Sensitivity Study of Brake Creep Groan

2021 ◽  
Vol 31 (16) ◽  
Author(s):  
Shaun Smith ◽  
James Knowles ◽  
Byron Mason ◽  
Sean Biggs
Keyword(s):  
Periodic Orbits ◽  
Degrees Of Freedom ◽  
Initial Conditions ◽  
Period Doubling ◽  
Nonlinear Behavior ◽  
Sensitivity Study ◽  
Friction Model ◽  
Model Parameters ◽  
Period Doubling Bifurcations ◽  
Simple Models

Creep groan is the undesirable vibration observed in the brake pad and disc as brakes are applied during low-speed driving. The presence of friction leads to nonlinear behavior even in simple models of this phenomenon. This paper uses tools from bifurcation theory to investigate creep groan behavior in a nonlinear 3-degrees-of-freedom mathematical model. Three areas of operational interest are identified, replicating results from previous studies: region 1 contains repelling equilibria and attracting periodic orbits (creep groan); region 2 contains both attracting equilibria and periodic orbits (creep groan and no creep groan, depending on initial conditions); region 3 contains attracting equilibria (no creep groan). The influence of several friction model parameters on these regions is presented, which identify that the transition between static and dynamic friction regimes has a large influence on the existence of creep groan. Additional investigations discover the presence of several bifurcations previously unknown to exist in this model, including Hopf, torus and period-doubling bifurcations. This insight provides valuable novel information about the nature of creep groan and indicates that complex behavior can be discovered and explored in relatively simple models.

When is OGY Control More Than Just Pole Placement

1997 ◽  
Vol 07 (03) ◽  
pp. 691-699 ◽  
Author(s):  
Dragan Obradovic ◽  
Henning Lenz
Keyword(s):  
Periodic Orbits ◽  
Measurement Errors ◽  
Initial Conditions ◽  
Chaotic Map ◽  
Dynamical Behavior ◽  
Open Loop ◽  
The State ◽  
Pole Placement ◽  
Unstable Periodic Orbits ◽  
State Matrix

Deterministic chaotic systems give rise to very complex dynamical behavior in spite of the fact that they are usually of very low dimension. The exceptionally high sensitivity to changes in initial conditions makes dealing with these systems non-trivial due to inherent measurement errors and limited numerical precision. Within a chaotic attractor it is usually possible to identify unstable point attractors and unstable periodic orbits. One of the widely accepted techniques for stabilizing unstable point attractors and periodic orbits is the so called OGY controller method developed by Ott, Grebogi, and Yorke. In the case of stabilizing an unstable point attractor within the chaotic map, the OGY controller effectively forces the system to move on the corresponding stable manifold in the state-space. On the other hand, it can be shown that this strategy coincides with the design of a full state feedback controller that places the unstable eigenvalues of the state matrix of the locally linearized system at zero while keeping the location of the stable eigenvalues unchanged. When the stabilization of the original, open-loop system is the only goal, the OGY approach does not offer any advantage over other stabilizing control actions such as pole placement to arbitrary but stable eigenvalue locations. In addition, neither OGY nor arbitrary pole placement explicitly deal with the problem of noise sensitivity. Hence, when the original chaotic system is noise corrupted, it is not clear if the OGY approach is even close to being optimal with respect to noise cancelation with "acceptable" control action. Although the answer to this question is negative in the general case, there are situations where the optimal system behavior is achieved. The contribution of this paper is twofold. The first contribution is the rigorous discussion of the relationship between the OGY approach and the pole placement and the extension of the OGY method to stabilization of systems with more than one unstable eigenvalue. The second contribution of the paper is the proof that the OGY control approach to the equilibrium point stabilization in the presence of persistent, magnitude bounded process noise is actually optimal when the system performance is measured by the l∞-norm of the control signal. The proof is based on properties of the optimal l1-norm controller design and on the parameterization of all stabilizing controllers for a given linear system.

ATTRACTORS IN CONSERVATIVE SYSTEMS

2006 ◽  
Vol 16 (06) ◽  
pp. 1795-1807 ◽  
Author(s):  
G. CONTOPOULOS
Keyword(s):  
Black Holes ◽  
Hamiltonian System ◽  
Periodic Orbits ◽  
Basins Of Attraction ◽  
Unstable Periodic Orbits ◽  
Asymptotic Curves ◽  
Conservative Systems ◽  
Finite Distance

Normally, conservative systems do not have attractors. However, in a system with escapes, the infinity acts as an attractor. Furthermore, attractors may appear as singularities at a finite distance. We consider the basins of escape in a particular Hamiltonian system with escapes and the rates of escape for various values of the parameters. Then we consider the basins of attraction of a system of two fixed black holes, with particular emphasis on the asymptotic curves of its unstable periodic orbits.

A Four-Leaf Chaotic Attractor of a Three-Dimensional Dynamical System

2015 ◽  
Vol 25 (02) ◽  
pp. 1530003 ◽  
Author(s):  
Tomoyuki Miyaji ◽  
Hisashi Okamoto ◽  
Alex D. D. Craik
Keyword(s):  
Dynamical System ◽  
Three Dimensional ◽  
Period Doubling ◽  
Numerical Verification ◽  
Unstable Periodic Orbits ◽  
Verification Method ◽  
Stable Periodic ◽  
Approach Infinity ◽  
Dimensional Dynamical System ◽  
Autonomous Dynamical System

A three-dimensional autonomous dynamical system proposed by Pehlivan is untypical in simultaneously possessing both unbounded and chaotic solutions. Here, this topic is studied in some depth, both numerically and analytically. We find, by standard methods, that four-leaf chaotic orbits result from a period-doubling cascade; we identify unstable fixed points and both stable and unstable periodic orbits; and we examine how initial data determines whether orbits approach infinity or a stable periodic orbit. Further, we describe and apply a strict numerical verification method that rigorously proves the existence of sequences of period doublings.

scholarly journals Chaotic breakdown of a periodically forced, weakly damped pendulum

1992 ◽  
Vol 34 (2) ◽  
pp. 153-173 ◽  
Author(s):  
Peter J. Bryant
Keyword(s):  
Phase Space ◽  
Periodic Solutions ◽  
Initial Conditions ◽  
Period Doubling ◽  
Dimensionless Frequency ◽  
Frequency Range ◽  
Time Intervals ◽  
Maximum Acceleration ◽  
Periodic Oscillations ◽  
Stable Periodic

AbstractAn investigation is made of the transition from periodic solutions through nearly-periodic solutions to chaotic solutions of the differential equation governing forced coplanar motion of a weakly damped pendulum. The pendulum is driven by horizontal, periodic forcing of the pivot with maximum acceleration Є g and dimensionless frequency ω As the forcing frequency ω is decreased gradually at a sufficiently large forcing amplitude Є, it has been shown previously that the pendulum progresses from symmetric oscillations of period T (= 2 π/ω) into a symmetry-breaking, period-doubling sequence of stable, periodic oscillations. There are two related forms of asymmetric, stable oscillations in the sequence, dependent on the initial conditions. When the frequency is decreased immediately beyond the sequence, the oscillations become unstable but remain in the neighbourhood in (θ,) phase space of one or other of the two forms of periodic oscillations, where θ(t) is the pendulum angle with the downward vertical. As the frequency is decreased further, the oscillations move intermittently between the neighbourhoods in (θ,) phase space of each of the two forms of periodic oscillations, in paired nearly-periodic oscillations. Further decrease of the forcing frequency leads to time intervals in which the motion is strongly unstable, with the pendulum passing intermittently over the pivot, interspersed with time intervals when the motion is nearly-periodic and only weakly unstable. The strongly-unstable intervals dominate in fully chaotic oscillations. Windows of independent, stable, periodic oscillations occur throughout the frequency range investigated. It is shown in an appendix how the Floquet method may be interpreted to describe the linear stability of the periodic and nearly-periodic solutions, and the windows of periodic oscillations in the investigated frequency range are listed in a second appendix.

HOPF BIFURCATION FROM LINES OF EQUILIBRIA WITHOUT PARAMETERS IN MEMRISTOR OSCILLATORS

2010 ◽  
Vol 20 (02) ◽  
pp. 437-450 ◽  
Author(s):  
MARCELO MESSIAS ◽  
CRISTIANE NESPOLI ◽  
VANESSA A. BOTTA
Keyword(s):  
Hopf Bifurcation ◽  
Periodic Orbits ◽  
Initial Conditions ◽  
Piecewise Linear ◽  
Equilibrium Points ◽  
Three Dimensional ◽  
Fixed Set ◽  
Electronic Element ◽  
Stable Periodic ◽  
Parameter Values

The memristor is supposed to be the fourth fundamental electronic element in addition to the well-known resistor, inductor and capacitor. Named as a contraction for memory resistor, its theoretical existence was postulated in 1971 by L. O. Chua, based on symmetrical and logical properties observed in some electronic circuits. On the other hand its physical realization was announced only recently in a paper published on May 2008 issue of Nature by a research team from Hewlett–Packard Company. In this work, we present the bifurcation analysis of two memristor oscillators mathematical models, given by three-dimensional five-parameter piecewise-linear and cubic systems of ordinary differential equations. We show that depending on the parameter values, the systems may present the coexistence of both infinitely many stable periodic orbits and stable equilibrium points. The periodic orbits arise from the change in local stability of equilibrium points on a line of equilibria, for a fixed set of parameter values. This phenomenon is a kind of Hopf bifurcation without parameters. We have numerical evidences that such stable periodic orbits form an invariant surface, which is an attractor of the systems solutions. The results obtained imply that even for a fixed set of parameters the two systems studied may or may not present oscillations, depending on the initial condition considered in the phase space. Moreover, when they exist, the amplitude of the oscillations also depends on the initial conditions.

scholarly journals Chaos in Relativity and Cosmology

1999 ◽  
Vol 172 ◽  
pp. 1-16
Author(s):  
G. Contopoulos ◽  
N. Voglis ◽  
C. Efthymiopoulos
Keyword(s):  
Black Holes ◽  
General Solution ◽  
Periodic Orbits ◽  
Rest Mass ◽  
Scattering Problem ◽  
Period Doubling ◽  
Characteristic Number ◽  
Type I ◽  
Chaotic Scattering ◽  
Mixmaster Model

AbstractChaos appears in various problems of Relativity and Cosmology. Here we discuss (a) the Mixmaster Universe model, and (b) the motions around two fixed black holes, (a) The Mixmaster equations have a general solution (i.e. a solution depending on 6 arbitrary constants) of Painlevé type, but there is a second general solution which is not Painlevé. Thus the system does not pass the Painlevé test, and cannot be integrable. The Mixmaster model is not ergodic and does not have any periodic orbits. This is due to the fact that the sum of the three variables of the system (α + β + γ) has only one maximum for τ = τm and decreases continuously for larger and for smaller τ. The various Kasner periods increase exponentially for large τ. Thus the Lyapunov Characteristic Number (LCN) is zero. The “finite time LCN” is positive for finite τ and tends to zero when τ → ∞. Chaos is introduced mainly near the maximum of (α + β + γ). No appreciable chaos is introduced at the successive Kasner periods, or eras. We conclude that in the Belinskii-Khalatnikov time, τ, the Mixmaster model has the basic characteristics of a chaotic scattering problem, (b) In the case of two fixed black holes M1 and M2 the orbits of photons are separated into three types: orbits falling into M1 (type I), or M2 (type II), or escaping to infinity (type III). Chaos appears because between any two orbits of different types there are orbits of the third type. This is a typical chaotic scattering problem. The various types of orbits are separated by orbits asymptotic to 3 simple unstable orbits. In the case of particles of nonzero rest mass we have intervals where some periodic orbits are stable. Near such orbits we have order. The transition from order to chaos is made through an infinite sequence of period doubling bifurcations. The bifurcation ratio is the same as in classical conservative systems.

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