Intermittency reinjection in the logistic map

Just below a Period-3 window, the logistic map exhibits intermittency. Then, the third iterate of this map has been widely used to explain the chaotic intermittency concept. Much attention has been paid to describing the behavior around the vanished fixed points, the tangent bifurcation, and the formation of the characteristic channel between the map and the diagonal for type-I intermittency. However, the reinjection mechanism has not been deeply analyzed. In this paper, we studied the reinjection processes for the three fixed points around which intermittency is generated. We calculated the reinjection probability density function, the probability density of the laminar lengths, and the characteristic relation. We found that the reinjection mechanisms have broader behavior than the usually used uniform reinjection. Furthermore, the reinjection processes depend on the fixed point.Fil: Elaskar, Sergio Amado. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Estudios Avanzados en Ingeniería y Tecnología. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto de Estudios Avanzados en Ingeniería y Tecnología; ArgentinaFil: del Río, Ezequiel. Escuela Tecnica Superior de Ingenieros Aeronauticos; España. Universidad Politécnica de Madrid; EspañaFil: Elaskar, Silvina Azul. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas; Argentin

Intermittency reinjection probability density function with and without noise effects.

Intermittency phenomenon is a continuous route from regular to chaotic behaviour. Intermittency is an occurrence of a signal that alternates chaotic bursts between quasi-regular periods called laminar phases, driven by the so called reinjection probability density function (RPD). In this paper is introduced a new technique to obtain the RPD for type-II and III intermittency. The new RPD is more general than the classical one and includes the classical RPD as a particular case. The probabilities of the laminar length, the average laminar lengths and the characteristic relations are determined with and without lower bound of the reinjection in agreement with numerical simulations. Finally, it is analyzed the noise effect in intermittency. A method to obtain the noisy RPD is developed extending the procedure used in the noiseless case. The analytical results show a good agreement with numerical simulations

Open FOAM simulations of the supersonic flow around cones at angles of attack

The supersonic flow around conical bodies is a very important issue in aerospace engineering, with many applications in internal and external supersonic aerodynamics. Non-viscous supersonic flow about yawing cones is essentially 3-dimensional, but it shows some characteristics regarding the conical flow around circular cones with zero angle of attack. In this latter case, the complete flow structure is axisymmetric and can be described by an ordinary differential equation known as the Taylor-Maccoll equation.Fil: Lorenzon, Denis. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Departamento de Aeronáutica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Estudios Avanzados en Ingeniería y Tecnología. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto de Estudios Avanzados en Ingeniería y Tecnología; ArgentinaFil: Elaskar, Sergio Amado. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Departamento de Aeronáutica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Estudios Avanzados en Ingeniería y Tecnología. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto de Estudios Avanzados en Ingeniería y Tecnología; Argentin

Reduced three-wave model to study the hard transition to chaotic dynamics in Alfven wave-fronts

The derivative nonlinear Schrödinger (DNLS) equation, describing propagation of circularly polarized Alfven waves of finite amplitude in a cold plasma, is truncated to explore the coherent, weakly nonlinear, cubic coupling of three waves near resonance, one wave being linearly unstable and the other waves damped. In a reduced three-wave model (equal damping of daughter waves, three-dimensional flow for two wave amplitudes and one relative phase), no matter how small the growth rate of the unstable wave there exists a parametric domain with the flow exhibiting chaotic dynamics that is absent for zero growth-rate. This hard transition in phase-space behavior occurs for left-hand (LH) polarized waves, paralelling the known fact that only LH time-harmonic solutions of the DNLS equation are modulationally unstable

E-beam propagation and interaction with atmosphere

This study purports to investigate whether a conductive tether left uninsulated and electrically floating in LEO could serve as an effective e-beam source to produce artificial auroras. An electrically floating tether comes out biased highly negative over most of its length. Ambient ions impacting it with KeV energies liberate secondary electrons, which are locally accelerated through the 2D tether voltage-bias, race down magnetic lines, and result in peak auroral emissions at about 120-160 km altitude. Since no current flows at either tether end, a bare-tether e-beam is fully free of spacecraft charging problems. Beam propagation and beam-atmosphere interactions need be modelled in a simple but quantitative way so as to allow a satisfactory discussion of observational options and their feasibility. The evolution in the energy spectrum of secondary electrons, their pitch distribution, and beam broadening due to collisions with neutrals, which would result in a broader but weaker tether footprint in the E-layer, need be modelled. Relations between particle/energy flux values, and ionization and accompanying emission rates, are considered

Acoplamiento coherente de cuatro ondas de Alfven

Interacciones no lineales de ondas de Alfvén existen tanto para plasmas en el espacio como en laboratorios, con efectos que van desde calentamiento hasta conducción de corriente. Un ejemplo de emisión de ondas de Alfvén en ingeniería aparece en amarras espaciales. Estos dispositivos emiten ondas en estructuras denominadas “Alas de Alfvén”. La ecuación Derivada no lineal de Schrödinger (DNLS) posee la capacidad de describir la propagación de ondas de Alfvén de amplitud finita circularmente polarizadas tanto para plasmas fríos como calientes. En esta investigación, dicha ecuación es truncada con el objetivo de explorar el acoplamiento coherente, débilmente no lineal y cúbico de cuatro ondas cerca de resonancia (k1 + k2 = k3 + k4). La onda 1 que corresponde al vector de onda k1 puede ser linealmente inestable y las tres restantes ondas 2, 3 y 4, correspondientes a k2, k3 y k4 respectivamente, son amortiguadas. Por medio de la utilización de este modelo se genera un flujo 5D formado por cuatro amplitudes y una fase relativa. En una serie de trabajos previos se ha analizado la transición dura hacia caos en flujos 3D (Sanmartín et al., 2004) y 4D (Elaskar et al., 2005; Elaskar et al., 2006; Sánchez-Arriaga et al., 2007). Se presenta en este artículo un análisis teórico-numérico del comportamiento del sistema cuando la tasa de crecimiento de la onda inestable es nula

2015-2020 Academic, Research and Service Report of the Aeronautical Department of the National University of Córdoba

The Aeronautical Department of the National University of Córdoba has the task of training professionals to develop the activities that correspond to the aerospace field with integrity, suitability and social responsibility while preserving the environment. It also promotes research and development by actively participating in innovative projects, making progress known through publications and scientific dissemination. The Department’ staff also works on establishing multicultural ties through cooperation agreements with national and international institutions. This article aims to report the performance of the Department in the academic, scientific and management fields in the last 5 years.Fil: Schulz, Walkiria. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Departamento de Aeronáutica; ArgentinaFil: Cid, Guillermo. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Departamento de Aeronáutica; ArgentinaFil: Elaskar, Sergio Amado. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Estudios Avanzados en Ingeniería y Tecnología. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto de Estudios Avanzados en Ingeniería y Tecnología; Argentin

Type-I intermittency with discontinuous reinjection probability density in a truncation model of the derivative nonlinear Schrödinger equation

In previous papers, the type-I intermittent phenomenon with continuous reinjection probability density (RPD) has been extensively studied. However, in this paper type-I intermittency considering discontinuous RPD function in one-dimensional maps is analyzed. To carry out the present study the analytic approximation presented by del Río and Elaskar (Int. J. Bifurc. Chaos 20:1185-1191, 2010) and Elaskar et al. (Physica A. 390:2759-2768, 2011) is extended to consider discontinuous RPD functions. The results of this analysis show that the characteristic relation only depends on the position of the lower bound of reinjection (LBR), therefore for the LBR below the tangent point the relation {Mathematical expression}, where {Mathematical expression} is the control parameter, remains robust regardless the form of the RPD, although the average of the laminar phases {Mathematical expression} can change. Finally, the study of discontinuous RPD for type-I intermittency which occurs in a three-wave truncation model for the derivative nonlinear Schrodinger equation is presented. In all tests the theoretical results properly verify the numerical dat

Fully 3-wave model to study the hard transition to chaotic dynamics in alfven wave-fronts

The derivative nonlinear Schrödinger (DNLS) equation, describing propagation of circularly polarized Alfven waves of finite amplitude in a cold plasma, is truncated to explore the coherent, weakly nonlinear coupling of three waves near resonance, one wave being linearly unstable and the other waves damped. No matter how small the growth rate of the unstable wave, the four-dimensional flow for the three wave amplitudes and a relative phase, with both resistive damping and linear Landau damping, exhibits chaotic relaxation oscillations that are absent for zero growth-rate. This hard transition in phase-space behavior occurs for left-hand (LH) polarized waves, paralleling the known fact that only LH time-harmonic solutions of the DNLS equation are modulationally unstable. The parameter domain developing chaos is much broader than the corresponding domain in a reduced 3-wave model that assumes equal dampings of the daughter wave

The Teaching of Gas Dynamics in the National University of Cordoba - UNC

This paper presents the teaching and research activities carried out at the National University of Cordoba (UNC) on issues directly related to Gas Dynamics. Currently, this University offers three courses on this subject: Gas Dynamics I, Gas Dynamics II and Advanced Gas Dynamics. The first two correspond to undergraduate studies, while the third to graduate studies. Gas Dynamics I is a required subject for all Aeronautical Engineering students at UNC, and represents the most advanced degree course within the area of Fluid Mechanics taught at the Department of Aeronautics. While Gas Dynamics II is an elective course that is only taken by students who are interested in deepening concepts in compressible flows. On the other hand, Advanced Gas Dynamics is a valid course for the Aerospace Master´s Degree and the Doctorate in Engineering Sciences. In addition, the growth in activity at the UNC in recent years stands out, both in the number of professors trained in the area, as well as in the number of Undergraduate, Master and Doctoral Theses and in the number of research projects.Fil: Elaskar, Sergio Amado. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Estudios Avanzados en Ingeniería y Tecnología. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto de Estudios Avanzados en Ingeniería y Tecnología; ArgentinaFil: Cid, Guillermo. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Departamento de Aeronáutica; ArgentinaFil: Schulz, Walkiria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Estudios Avanzados en Ingeniería y Tecnología. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto de Estudios Avanzados en Ingeniería y Tecnología; Argentina. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Departamento de Aeronáutica; Argentin