Search results for "Persio"

On structural phase transitions inn-butylammonium chloroantimonate(III) and chlorobismuthate(III) crystals: x-ray, differential scanning calorimetry,…

1997

Numerous structural phase transitions are detected in new crystals of the n-butylammonium compounds: , and by means of differential scanning calorimetry, dilatometric and dielectric dispersion (1 kHz - 1 MHz) studies. For the transitions the basic thermodynamic data are determined. Interesting dielectric properties are found in a metastable form of the crystals. Debye-like dispersion of the electric permittivity between 30 and 800 MHz is observed around the 310 K phase transition for this crystal. The activation energy of the reorientation of the n-butylammonium cations is found to be 16 kJ . The structure of ( form) has been refined to R = 0.0439 and shows isolated units and two non-equiva…

Prologo

2010

Interaction between turbulent structures and particles in roughened channel

2016

Abstract The distribution of inertial particles in turbulent flows is highly non-uniform and is driven by the local dynamics of the turbulent structures of the underlying carrier flow field. In the specific context of dilute particle-laden wall-bounded flows, deposition and resuspension mechanisms are dominated by the interaction between inertial particles and coherent turbulent structures characteristic of the wall region. The macroscopic behavior of these two-phase systems is influenced by particle inertia, which plays a role at the microscale of a single dispersed element. These turbulent structures, which control the turbulent regeneration cycles, are strongly affected by the wall rough…

Polarization-domain-wall complexes in fiber lasers

2013

To study the possible build-up of polarization-domain-walls (PDWs) in fiber laser cavities, an erbium-doped fiber ring laser was used and a wide range of vector polarization dynamics that can be selected at a given pump power, by using the degrees of freedom of two intracavity polarization controllers (PC) was investigated. A simple theoretical model that explains polarization switching in fiber ring lasers featuring a normally dispersive cavity with a typical, moderate, level of birefringence is presented. Such polarization dynamics, based on a special class of polarization-domain-wall structures, agrees qualitatively well with experimental observations. The paper stresses on the complex a…

Hamiltonian tools for the analysis of optical polarization control

2011

Import JabRef; International audience; The study of the polarization dynamics of two counterpropagating beams in optical fibers has recently been the subject of a growing renewed interest, from both the theoretical and experimental points of view. This system exhibits a phenomenon of polarization attraction, which can be used to achieve a complete polarization of an initially unpolarized signal beam, almost without any loss of energy. Along the same way, an arbitrary polarization state of the signal beam can be controlled and converted into any other desired state of polarization, by adjusting the polarization state of the counterpropagating pump beam. These properties have been demonstrate…

Modulational instability and generation of self-induced transparency solitons in resonant optical fibers

2009

International audience; We consider continuous-wave propagation through a fiber doped with two-level resonant atoms, which is described by a system of nonlinear Schrodinger-Maxwell-Bloch (NLS-MB) equations. We identify the modulational instability (MI) conditions required for the generation of ultrashort pulses, in cases of both anomalous and normal GVD (group-velocity dispersion). It is shown that the self-induced transparency (SIT) induces non-conventional MI sidebands. The main result is a prediction of the existence of both bright and dark SIT solitons in the anomalous and normal GVD regimes.

Euro Area Structural Convergence? A Multi-Criterion Cluster Analysis

2015

Abstract This paper proposes a classification of the old member countries of the euro area in a structural data rich environment and run a convergence analysis using the same framework. First, we use a clustering approach and identify two structurally distinct clusters of countries that are not modified between 1999 and 2012: the South Countries Group (SCG) – composed of Greece, Italy, Portugal and Spain – and the Other Countries Group (OCG). Second, we propose a convergence metrics and reach three key findings: (i) increase over time of the between-clusters׳ dispersion; (ii) diverging demographics and innovation performance into the OCG, and (iii) an unfortunate convergence towards high la…

Heavy Gas Dispersion Modelling Over a Topographically Complex Mesoscale: A CFD Based Approach

2005

Abstract: Potentially dangerous events involving heavy gas dispersion and their severe consequences have been largely publicized by the media. Simplified models have been widely applied to describe the effects of these accidents. However, most simplified models deal with flat terrain scenarios and are based on quite crude simplifications of the complex phenomenology involved. In this paper the possibility of simulating the dispersion of heavy gas clouds over a large topographically complex area (tens of km) by a general purpose computational fluid dynamics (CFD) code is investigated. The aim is that of setting up a tool able to produce a realistic description of such dispersion processes, w…

Population dynamics and genetics of European Pond Turtle Emys orbicularis

2013

Dispersal, characterized by the movements of individuals in space leading to gene flows, allows populations to connect. The study of dispersal has become of essential importance to predict the consequences of global changes on the population structures and dynamics. Species with limited dispersal, such as chelonians, are particularly threatened by these phenomena. Our study aimed at analyzing the dispersal of the European pond turtle (Emys orbicularis), in decline in Europe, in a habitats fragmentation context and determining the causes of this behavior through analysis of population dynamics and genetics. Our results show, firstly, that the slow generation time in Emys orbicularis (about 1…

Caractérisation et prédiction du rendement de projection lors du procédé de projection à froid – cas de la métallisation des polymères

2020

This thesis work deals with the cold spray metallization of polymer substrates by aiming at an optimal deposition efficiency using experimental analysis combined with numerical simulation. Experimental observations of the powder jet using an ombroscopic analysis have revealed a generic behavior consisting of a uniform confined zone at the immediate exit of the nozzle followed by a dispersed zone. The supersonic flow at the nozzle exit being essentially axial, the powders are entrained to form a uniform jet. Beyond a certain distance, a dispersion appears. This distance is very important because it characterizes the behavior of the powders. It can alter the conditions for the elaboration of …