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Dive into the research topics where C. Cabeza is active.

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Featured researches published by C. Cabeza.


The Physics Teacher | 2014

Angular velocity and centripetal acceleration relationship

Martín Monteiro; C. Cabeza; Arturo C. Marti; Patrik Vogt; Jochen Kuhn

During the last few years, the growing boom of smartphones has given rise to a considerable number of applications exploiting the functionality of the sensors incorporated in these devices. A sector that has unexpectedly taken advantage of the power of these tools is physics teaching, as reflected in several recent papers.1–10 In effect, the use of smartphones has been proposed in several physics experiments spanning mechanics, electromagnetism, optics, oscillations, and waves, among other subjects. Although mechanical experiments have received considerable attention, most of them are based on the use of the accelerometer.1–8 An aspect that has received less attention is the use of rotation sensors or gyroscopes.9,10 An additional advance in the use of these devices is given by the possibility of obtaining data using the accelerometer and the gyroscope simultaneously. The aim of this paper is to consider the relation between the centripetal acceleration and the angular velocity. Instead of using a formal ...


Chaos Solitons & Fractals | 1995

The nonlinear gain and the onset of chaos in a semiconductor laser with optical feedback

Cristina Masoller; A.C. Sicardi Schifino; C. Cabeza

Abstract The effect of the inclusion of nonlinear gain saturation in the governing equations of a semiconductor laser with optical feedback is numerically analyzed. The dependence of the route to chaos on the intensity of the nonlinear term and on the form of gain saturation, are considered. It is found that the inclusion of gain saturation causes significant changes in the behavior of the laser with respect to the route found when a linear optical gain is used [5]. We find that the value of the feedback rate at which the transition to coherence collapsed state occurs increases, as the intensity of the nonlinear term is augmented. In order to study the influence of the form of gain saturation, three different forms of optical gain, that result from spectral and kinetic hole burning or carrier heating, with an explicit intensity dependence are considered. The route to chaos is the same for the three forms considered but the parameters at which transition between attractors occur depend slightly on the form of gain saturation used. The calculated Lyapunov exponents, dimension and entropy confirm the fractal and chaotic nature of the attractors found.


The Physics Teacher | 2016

Exploring the atmosphere using smartphones

Martín Monteiro; Patrik Vogt; Cecilia Stari; C. Cabeza; Arturo C. Marti

The characteristics of the inner layer of the atmosphere, the troposphere, are determinant for the earths life. In this experience we explore the first hundreds of meters using a smartphone mounted on a quadcopter. Both the altitude and the pressure are obtained using the smartphones sensors. We complement these measures with data collected from the flight information system of an aircraft. The experimental results are compared with the International Standard Atmosphere and other simple approximations: isothermal and constant density atmospheres.


IEEE Journal of Quantum Electronics | 1995

Effect of the nonlinear gain in the visibility of a semiconductor laser with incoherent feedback in the coherence collapsed regime

Cristina Masoller; C. Cabeza; A.C. Sicardi Schifino

We study the influence of the gain saturation parameter /spl epsiv/ on the visibility of a semiconductor laser subject to optical feedback in the coherence collapsed state. The experimental measurements are compared with the results obtained integrating the Lang and Kobayashi equations and a good agreement is found varying the amount of feedback and using different values of /spl epsiv/. The analysis reveals that there is a best value of /spl epsiv/ that fits the experimental measurements and that, for this value of /spl epsiv/, the values of /spl gamma/ found are in the expected relation with the attenuation used experimentally. >


Optics Communications | 1993

Chaotic properties of the coherence collapsed state of laser diodes with optical feedback

Cristina Masoller; A.C. Sicardi Schifino; C. Cabeza

Abstract The characterization of the geometrical and statistical properties of the coherence collapsed state of laser diodes with optical feedback is done by means of dimension analysis and the spectrum of Lyapunov exponents. The dimension calculation evidences the fractal and low-dimensional structure of the attractor, while the spectrum of Lyapunov exponents unambiguously confirms the chaotic nature of the coherence collapsed state. In addition, we investigated the transition from quasiperiodicity to chaos as the feedback parameter was increased. The detection by Poincare section analysis and power spectrum of three-period doubling bifurcations of a two-dimensional torus is presented.


Physics of Fluids | 2009

Two-layer stratified flows over pronounced obstacles at low-to-intermediate Froude numbers

C. Cabeza; Juan Varela; Italo Bove; Daniel Freire; Arturo C. Marti; L.G. Sarasúa; Gabriel Usera; Raúl Montagne; Moacyr Araujo

Two-layer stratified flows over abrupt topographic obstacles, simulating relevant situations in oceanographic problems, are investigated numerically and experimentally in a simplified two-dimensional situation. Experimental results and numerical simulations are presented at low-to-intermediate Froude numbers for two different obstacles: one semicylindrical and the other prismatic. In both cases, four different flow regimes downstream of the obstacles are found: (I) subcritical flow, (II) internal hydraulic jump, (III) Kelvin–Helmholtz instability at the interface, and (IV) shedding of billows. The critical values of the Froude number for the transition between different regimes depend strongly on the shape of the obstacle. In regime (III), we show that the characteristics of the lee wave that appears past the obstacle can be explained with a theoretical stability analysis. Almost independence of the vortex shedding frequency with upstream velocity is observed and explained.


Chaos | 2015

Organization and identification of solutions in the time-delayed Mackey-Glass model

Pablo Amil; C. Cabeza; Cristina Masoller; Arturo C. Marti

Multistability in the long term dynamics of the Mackey-Glass (MG) delayed model is analyzed by using an electronic circuit capable of controlling the initial conditions. The systems phase-space is explored by varying the parameter values of two families of initial functions. The evolution equation of the electronic circuit is derived and it is shown that, in the continuous limit, it exactly corresponds to the MG model. In practice, when using a finite set of capacitors, an excellent agreement between the experimental observations and the numerical simulations is manifested. As the delay is increased, different periodic or aperiodic solutions appear. We observe abundant periodic solutions that have the same period but a different alternation of peaks of dissimilar amplitudes and propose a novel symbolic method to classify these solutions.


Journal of Physics: Conference Series | 2011

Scaling Laws in the Transient Dynamics of Firefly-like Oscillators

Nicolás Rubido; C. Cabeza; G. M. Ramírez Ávila; A Martí

Fireflies constitute a paradigm of pulse-coupled oscillators. In order to tackle the problems related to synchronisation transients of pulse-coupled oscillators, a Light-Controlled Oscillator (LCO) model is presented. A single LCO constitutes a one-dimensional relaxation oscillator described by two distinct time-scales meant to mimic fireflies in the sense that: it is capable of emitting light in a pulse-like fashion and detect the emitted by others in order to adjust its oscillation. We present dynamical results for two interacting LCOs in the torus for all possible coupling configurations. Transient times to the synchronous limit cycle are obtained experimentally and numerically as a function of initial conditions and coupling strengths. Scaling laws are found based on dimensional analysis and critical exponents calculated, thus, global dynamic is restricted. Furthermore, an analytical orthogonal transformation that allows to calculate Floquet multipliers directly from the time series is presented. As a consequence, local dynamics is also fully characterized. This transformation can be easily extended to a system with an arbitrary number of interacting LCOs.


Journal of Physics: Conference Series | 2010

Effect of turbulent fluctuations on the behaviour of fountains in stratified environments

Daniel Freire; C. Cabeza; S Pauletti; Gustavo Sarasua; Italo Bove; Gabriel Usera; Arturo C Martí

The interaction between a turbulent fountain and its stratified environment was studied. A heavy fluid, cold water, was injected vertically upwards into a linearly stratified medium. The round heavy-fluid jet reaches a maximum height before it begins to fall due to the effect of gravity. Because of the effects of friction and mixing, the vertical momentum and density of the jet fluid decrease as it submerges to an intermediate height of zero buoyancy. At this point, the jet fluid spreads as a horizontal front, intruding into the stratified environment. The degree of fluctuation in the proximity of the injection point was studied under both unrestricted- and restricted-flow configurations at the injection, using two differently sized stainless-steel woven-wire screens at the injection port as flow-restricting means. Using visualization and velocimetry techniques, both maximum and spreading heights were found to decrease with increasing turbulence at the point of injection.


Chaos Solitons & Fractals | 2013

Periodicity hubs and wide spirals in a two-component autonomous electronic circuit

C. Cabeza; Carlos A. Briozzo; Rodrigo Garcia; Joana G. Freire; Arturo C. Marti; Jason A. C. Gallas

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Arturo C. Marti

Federal University of Paraíba

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Cristina Masoller

Polytechnic University of Catalonia

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Moacyr Araujo

Federal University of Pernambuco

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Raúl Montagne

Federal University of Pernambuco

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Patrik Vogt

University of Education

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Jochen Kuhn

Kaiserslautern University of Technology

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Thorsten Pöschel

University of Erlangen-Nuremberg

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