A Riemann solver at a junction compatible with a homogenization limit

We consider a junction regulated by a traffic lights, with n incoming roads and only one outgoing road. On each road the Phase Transition traffic model, proposed in [6], describes the evolution of car traffic. Such model is an extension of the classic Lighthill-Whitham-Richards one, obtained by assuming that different drivers may have different maximal speed. By sending to infinity the number of cycles of the traffic lights, we obtain a justification of the Riemann solver introduced in [9] and in particular of the rule for determining the maximal speed in the outgoing road.Comment: 19 page

The Godunov Method for a 2-Phase Model

We consider the Godunov numerical method to the phase-transition traffic model, proposed in [6], by Colombo, Marcellini, and Rascle. Numerical tests are shown to prove the validity of the method. Moreover we highlight the differences between such model and the one proposed in [1], by Blandin, Work, Goatin, Piccoli, and Bayen.Comment: 13 page

NonLocal Systems of Balance Laws in Several Space Dimensions with Applications to Laser Technolog

For a class of systems of nonlinear and nonlocal balance laws in several space dimensions, we prove the local in time existence of solutions and their continuous dependence on the initial datum. The choice of this class is motivated by a new model devoted to the description of a metal plate being cut by a laser beam. Using realistic parameters, solutions to this model obtained through numerical integrations meet qualitative properties of real cuts. Moreover, the class of equations considered comprises a model describing the dynamics of solid particles along a conveyor belt

Dynamics and ordering of weakly Brownian particles in directional drying

Drying of particle suspensions is an ubiquitous phenomenon with many natural and practical applications. In particular, in unidirectional drying, the evaporation of the solvent induces flows which accumulate particles at the liquid/air interface. The progressive build-up of a dense region of particles can be used, in particular, in the processing of advanced materials and architectures while the development of heterogeneities and defects in such systems is critical to their function. A lot of attention has thus been paid to correlate the flow and particles dynamics to the ordering of particles. However, dynamic observation at the particle scale and its correlation with local particle ordering are still missing. Here we show by measuring the particle velocities with high frame rate laser scanning confocal microscopy that the ordering of weakly Brownian particles during directional drying in a Hele-Shaw cell opened on one side depends on the particle velocity. Under the ambient and experimental conditions presented in the following, the particle velocities accumulate in two branches. A higher degree of ordering is found for the branch of faster particle velocity which we explain by an increase in the pressure drop which drags the particles into a denser packing as the flow velocity increases. This counter-intuitive behaviour is the opposite to what is found with Brownian particles, which can reorganize by Brownian motion into denser packing during drying, as long as the flow velocity is not too high. These results show that different kinetic conditions can be used to obtain dense, defect-free regions of particles after drying. In particular, it suggests that rapid, directional drying could be used to control the crystallinity of particle deposits.Comment: 10 pages, 12 figure

Modeling and analysis of pooled stepped chutes

We consider an application of pooled stepped chutes where the transport in each pooled step is described by the shallow--water equations. Such systems can be found for example at large dams in order to release overflowing water. We analyze the mathematical conditions coupling the flows between different chutes taken from the engineering literature. We present the solution to a Riemann problem in the large and also a well--posedness result for the coupled problem. We finally report on some numerical experiments.Comment: 17 pages, 31 figure

Coupling conditions for the 3x3 Euler system

This paper is devoted to the extension to the full $3\times3$ Euler system of the basic analytical properties of the equations governing a fluid flowing in a duct with varying section. First, we consider the Cauchy problem for a pipeline consisting of 2 ducts joined at a junction. Then, this result is extended to more complex pipes. A key assumption in these theorems is the boundedness of the total variation of the pipe's section. We provide explicit examples to show that this bound is necessary.Comment: 21 pages, 6 figure

Balance laws with integrable unbounded sources

We consider the Cauchy problem for a $n\times n$ strictly hyperbolic system of balance laws $$\{{array}{c} u_t+f(u)_x=g(x,u), x \in \mathbb{R}, t>0 u(0,.)=u_o \in L^1 \cap BV(\mathbb{R}; \mathbb{R}^n), | \lambda_i(u)| \geq c > 0 {for all} i\in \{1,...,n\}, \|g(x,\cdot)\|_{\mathbf{C}^2}\leq \tilde M(x) \in L1, {array}.$$ each characteristic field being genuinely nonlinear or linearly degenerate. Assuming that the $\mathbf{L}^1$ norm of $\|g(x,\cdot)\|_{\mathbf{C}^1}$ and \|u_o\|_{BV(\reali)} are small enough, we prove the existence and uniqueness of global entropy solutions of bounded total variation extending the result in [1] to unbounded (in $L^\infty$) sources. Furthermore, we apply this result to the fluid flow in a pipe with discontinuous cross sectional area, showing existence and uniqueness of the underlying semigroup.Comment: 26 pages, 4 figure

La relation entre aidé et aidant dans le couple adulte et entre parents aidants et enfants aidés

L'étude a cherché à évaluer la pertinence du questionnaire et de la démarche de l'enquête HSM-HSA pour mesurer la qualité de la relation entre aidant et aidé dans deux situations particulières : celle où l'aidant est le conjoint cohabitant d'une personne aidé de 18 à 59 ans ; celle où l'aidant est le père ou la mère cohabitant d'une personne de 18 à 29 ans. L'étude s'est faite en trois temps. D'abord, une exploitation de l'enquête HSM-HSA décrit les populations concernées selon différentes caractéristiques sociodémographiques et la qualité de la relation déclarée. Ensuite, une analyse qualitative de treize études de cas, basées sur entretiens, visites répétées et observations, décrit la relation entre aidant et aidé, et le contexte familial dans lequel elle s'inscrit. Enfin, une confrontation cas par cas de la situation décrite qualitativement et les réponses données à l'enquête HSM-HSA permet d'en repérer quelques décalages. Comme principaux résultats, l'étude met en évidence : une partialité de l'information recueillie par HSM-HSA auprès des seuls aidants ; une pauvreté des informations permettant de rendre les temporalités qui traversent la relation d'aide ; une difficulté de différencier entre intégration familiale descendante et ascendante qui, sur le terrain, semble s'opposer ; une imprécision sur la détermination du rang d'aidant

La cobertura mediática de las mujeres deportistas con discapacidad. Análisis de la prensa diaria de cuatro países europeos durante los Juegos Paralímpicos de Sidney 2000*

Las investigaciones sobre la mediatización de las mujeres deportistas muestran, por una parte, que éstas están menos representadas que los hombres, por otra, que su imagen está fuertemente sexualizada. Además, en contraposición a los hombres, los artículos de que son objeto las presentan generalmente en su papel de madre, mujer, etc.; es decir las enmarcan en ambientes no deportivos. Por añadidura, sabemos que en ciertos puntos el tratamiento mediático de deportistas con discapacidad es diferente al de quienes no la tienen. Pero ¿qué peculiaridades aparecen en el tratamiento mediático de las mujeres deportistas discapacitadas? El estudio de la cobertura de prensa de los Juegos Paralímpicos (Sidney 2000) presentado aquí (basado en un análisis cualitativo y cuantitativo de 108 artículos editados por periódicos alemanes, ingleses, españoles y franceses) muestra que, contrariamente a lo que se esperaba, las mujeres deportistas con discapacidad no están cuantitativamente menos representadas que los hombres. Por tanto, en este caso no hay estigmatización por ocultación específica. Sin embargo, ésta adopta formas más insidiosas. El análisis de los elementos cualitativos de los reportajes y de las fotos muestra que, efectivamente, las mujeres aparecen fuertemente “infantilizadas” y “trivializadas” (Jones, 1999) en los periódicos que cubren los Juegos Paralímpicos