DSpace Collection:
http://hdl.handle.net/10261/2864
2014-08-22T18:55:53ZViability and Resilience in the Dynamics of Language Competition
http://hdl.handle.net/10261/80421
Title: Viability and Resilience in the Dynamics of Language Competition
Authors: Castelló, Xavier; Vázquez, Federico; Eguíluz, Víctor M.; Loureiro-Porto, Lucía; San Miguel, Maxi; Chapel, Laetitia; Deffuant, Guillaume
Abstract: This chapter describes the a first case study applying viability based resilience,
presented in Chapter 2, on an individual based model (IBM). A particularly sen-
sitive issue is to derive macroscopic descriptions from these IBMs, involving a
limited number of variables. Indeed, as explained in Chapter 7, this is the con-
dition to make tractable the computation of the viability kernel and resilience
values. The chapter introduces Individual Based Models (IBMs) of language
competition, and explores, through computer simulations, the pattern dynamics
of these models and the qualitative role of the prestige and volatility parame-
ters. Then it proposes several approaches inspired by physics to perform the
derivation of macroscopic descriptions that are able to capture key aspects of the
phenomena observed in the IBMs. Finally, it presents an explicit calculation of
viability and resilience based on a macroscopic description.2013-07-31T12:24:23ZOptical delay dynamics and its applications
http://hdl.handle.net/10261/80418
Title: Optical delay dynamics and its applications
Authors: Fischer, Ingo; Larger, Laurent2013-07-31T12:02:42ZDynamical and Synchronization Properties of Delay-Coupled Lasers
http://hdl.handle.net/10261/80301
Title: Dynamical and Synchronization Properties of Delay-Coupled Lasers
Authors: González, Cristina M.; Soriano, M. C.; Torrent, M. C.; García-Ojalvo, Jordi; Fischer, Ingo
Abstract: This chapter (9) contains sections titled: Motivation: Why Coupling Lasers?, Dynamics of Two Mutually Delay-Coupled Lasers, Properties of Leader–Laggard Synchronization, Dynamical Relaying as Stabilization Mechanism for Zero-Lag Synchronization, Modulation Characteristics of Delay-Coupled Lasers, Conclusion.2013-07-30T07:44:31ZFrequency and phase locking of laser cavity solitons
http://hdl.handle.net/10261/54856
Title: Frequency and phase locking of laser cavity solitons
Authors: Ackemann, Thorsten; Noblet, Y.; Paulau, P. V.; McIntyre, C.; Colet, Pere; Firth, William J.; Oppo, Gian-Luca
Abstract: Self-localized states or dissipative solitons have the freedom of translation in systems with a homogeneous background. When compared to cavity solitons in coherently driven nonlinear optical systems, laser cavity solitons have the additional freedom of the optical phase. We explore the consequences of this additional Goldstone mode and analyze experimentally and numerically frequency and phase locking of laser cavity solitons in a vertical-cavity surface-emitting laser with frequency-selective feedback. Due to growth-related variations of the cavity resonance, the translational symmetry is usually broken in real devices. Pinning to different defects means that separate laser cavity solitons have different frequencies and are mutually incoherent. If two solitons are close to each other, however, their interaction leads to synchronization due to phase and frequency locking with strong similarities to the Adler-scenario of coupled oscillators.2012-08-21T08:44:17ZAll Optical Logical Operations Using Excitable Cavity Solitons
http://hdl.handle.net/10261/46984
Title: All Optical Logical Operations Using Excitable Cavity Solitons
Authors: Jacobo, Adrián; Gomila, Damià; Colet, Pere; Matías, Manuel A.
Abstract: We show theoretically that dissipative solitons arising in the transverse plane of nonlinear optical cavities show oscillatory and excitable regimes that can be used to perform all-optical logical operations. This allows for the construction of reconfigurable optical gates that can operate in parallel2012-03-13T10:56:44ZResonance Induced by Repulsive Links
http://hdl.handle.net/10261/46724
Title: Resonance Induced by Repulsive Links
Authors: Vaz Martins, Teresa; Toral, Raúl
Abstract: In nonlinear systems, the right amount of noise can amplify the response
to a weak periodic signal, by a phenomenon known as stochastic resonance
1
. It was
shown that the same constructive role can be played by any source of disorder
2
We study an Ising model in a network with disorder induced by the presence of both
attractive and repulsive links. The system is subjected to a sub-threshold periodic
signal, and the goal is to see how the response is enhanced for a given fraction of
repulsive links. This can model a network of spinlike neurons with excitatory and
inhibitory couplings. By means of numerical simulations, we ﬁnd that there is an
optimal probability of repulsive links, such that the coherent response is maximal,
and we propose a mechanism to explain this resonance.2012-03-07T16:03:02ZMapping time series to graphs: a brief overview of visibility algorithms
http://hdl.handle.net/10261/46409
Title: Mapping time series to graphs: a brief overview of visibility algorithms
Authors: Lacasa, Lucas; Luque, Bartolo
Abstract: In the last years a new approach for making time series analysis has appeared. This
new approach considers the mapping of time series to networks, in order to characterize the structure of time series (and therefore the dynamics that generated the series)
via characterization of the associated network. It makes use of several metrics recently
developed in the so called Complex Network theory, and makes a bridge between this
latter discipline and the more general aspects of time series analysis and nonlinear dynamics. While several possibilities have been proposed, here we focus on the so called
visibility algorithm, which has received much attention in the last two years. This
method has been shown to be well deﬁned as time series correlations are inherited
in the associated visibility graphs, opening the possibility of characterizing complex
signals from a brand new viewpoint. We will make an overview of the method, addressing two different possible mapping criteria (i.e. the visibility algorithm and the
horizontal visibility algorithm) for mapping series into graphs. This method captures
the correlations of a time series and encodes it in the topology of the associated graph.
After presenting the mapping properties, we will address within the visibility algorithms three fundamental problems in nonlinear time series analysis, namely (i) the
network characterization of fractional Brownian motion, (ii) the characterization of
uncorrelated processes, and (iii) the discrimination between randomness and chaos
through the visibility algorithm.2012-02-29T15:59:06ZNew Microscopic Connections of Thermodynamics
http://hdl.handle.net/10261/46146
Title: New Microscopic Connections of Thermodynamics
Authors: Plastino, A.; Casas, Montserrat
Abstract: This is a work that discusses the foundations of statistical mechanics (SM) by revisiting its
postulates in the case of the two main extant versions of the theory. A third one will here
we added, motivated by the desire for an axiomatics that possesses some thermodynamic
“flavor”, which does not happen with neither of the two main SM current formulations,
namely, those of Gibbs’ (1; 2), based on the ensemble notion, and of Jaynes’, centered on
MaxEnt (3; 4; 5).
One has to mention at the outset that we “rationally understand” some physical problem
when we are able to place it within the scope and context of a specific “Theory”. In turn, we
have a theory when we can both derive all the known interesting results and successfully
predict new ones starting from a small set of axioms. Paradigmatic examples are von
Neumann’s axioms for Quantum Mechanics, Maxwell’s equations for electromagnetism,
Euclid’s axioms for classical geometry, etc. (1; 3).
Boltzmann’s main goal in inventing statistical mechanics during the second half of the XIX
century was to explain thermodynamics. However, he did not reach the axiomatic stage
described above. The first successful SM theory was that of Gibbs (1902) (2), formulated on the
basis of four ensemble-related postulates (1). The other great SM theory is that of Jaynes’ (4),
based upon the MaxEnt axiom (derived from Information Theory): ignorance is to be extremized
(with suitable constraints).
Thermodynamics (TMD) itself has also been axiomatized, of course, using four macroscopic
postulates (6). Now, the axioms of SM and of thermodynamics belong to different worlds
altogether. The former speak of either “ensembles” (Gibbs), which are mental constructs,
or of “observers’ ignorance” (Jaynes), concepts germane to thermodynamics’ language, that
refers to laboratory-parlance. In point of fact, TMD enjoys a very particular status in the whole
of science, as the one and only theory whose axioms are empirical statements (1).
Of course, there is nothing to object to the two standard SM-axiomatics referred to
above. However, a natural question emerges: would it be possible to have a statistical
mechanics derived from axioms that speak, as far as possible, the same language as that of
thermodynamics? To what an extent is this feasible? It is our intention here that of attempting
a serious discussion of such an issue and try to provide answers to the query, following ideas
developed in (7; 8; 9; 10; 11; 12; 13).2012-02-23T13:21:06ZInteraction of oscillatory and excitable dissipative solitons in a nonlinear optical cavity
http://hdl.handle.net/10261/46139
Title: Interaction of oscillatory and excitable dissipative solitons in a nonlinear optical cavity
Authors: Gomila, Damià; Jacobo, Adrián; Matías, Manuel A.; Colet, Pere
Abstract: The interaction between stationary localized states have long been studied, but localized states may undergo a number of instabilities that lead to more
complicated dynamical regimes. In this case, the effects of the interaction are much
less known. This chapter addresses the problem of the interaction between oscillatory and excitable localized states in a Kerr cavity. These oscillatory structures
can be considered as non punctual oscillators with a highly non-trivial spatial coupling, which leads to rather complicated dynamics beyond what can be explained in
terms of simple coupled oscillators. We also explore the possibility of using coupled
excitable localized structures to build all-optical logical gates.2012-02-23T12:52:35ZSpace-time-dynamic model of passively-phased ring-geometry fiber laser array
http://hdl.handle.net/10261/45097
Title: Space-time-dynamic model of passively-phased ring-geometry fiber laser array
Authors: Bochove, Erik J; Aceves, Alejandro B.; Deiterding, Ralf;; Crabtree, Lily;; Braiman, Yehuda; Jacobo, Adrián; Colet, Pere
Abstract: We performed a linearized stability analysis and preliminary simulations of passive phasing in a CW operating ring-geometry fiber laser array coupled in an external cavity with a single-mode feedback fiber that functions as spatial filter. A two-element array with path length error is predicted to have a dynamically stable stationary operating state at the compputer operating wavelength.
Description: Fiber Lasers VII: Technology, Systems, and Applications2012-02-02T15:51:35Z