Search results for "APF"

Numerical Investigations of an Implicit Leapfrog Time-Domain Meshless Method

2014

Numerical solution of partial differential equations governing time domain simulations in computational electromagnetics, is usually based on grid methods in space and on explicit schemes in time. A predefined grid in the problem domain and a stability step size restriction need. Recently, the authors have reformulated the meshless framework based on smoothed particle hydrodynamics, in order to be applied for time domain electromagnetic simulation. Despite the good spatial properties, the numerical explicit time integration introduces, also in a meshless context, a severe constraint. In this paper, at first, the stability condition is addressed in a general way by allowing the time step inc…

Classical and quantum vortex leapfrogging in two-dimensional channels

2020

The leapfrogging of coaxial vortex rings is a famous effect which has been noticed since the times of Helmholtz. Recent advances in ultra-cold atomic gases show that the effect can now be studied in quantum fluids. The strong confinement which characterizes these systems motivates the study of leapfrogging of vortices within narrow channels. Using the two-dimensional point vortex model, we show that in the constrained geometry of a two-dimensional channel the dynamics is richer than in an unbounded domain: alongsize the known regimes of standard leapfrogging and the absence of it, we identify new regimes of backward leapfrogging and periodic orbits. Moreover, by solving the Gross-Pitaevskii…

Unconditionally stable meshless integration of time-domain Maxwell’s curl equations

2015

Grid based methods coupled with an explicit approach for the evolution in time are traditionally adopted in solving PDEs in computational electromagnetics. The discretization in space with a grid covering the problem domain and a stability step size restriction, must be accepted. Evidence is given that efforts need for overcoming these heavy constraints. The connectivity laws among the points scattered in the problem domain can be avoided by using meshless methods. Among these, the smoothed particle electromagnetics, gives an interesting answer to the problem, overcoming the limit of the grid generation. In the original formulation an explicit integration scheme is used providing, spatial a…

A brief overview on the numerical behavior of an implicit meshless method and an outlook to future challenges

2015

In this paper recent results on a leapfrog ADI meshless formulation are reported and some future challenges are addressed. The method benefits from the elimination of the meshing task from the pre-processing stage in space and it is unconditionally stable in time. Further improvements come from the ease of implementation, which makes computer codes very flexible in contrast to mesh based solver ones. The method requires only nodes at scattered locations and a function and its derivatives are approximated by means of a kernel representation. A perceived obstacle in the implicit formulation is in the second order differentiations which sometimes are eccesively sensitive to the node configurat…

Unconditionally stable meshless integration of Maxwell's eqautions

2013

How green neighbourhoods make cities more compact?t? A 2D microeconomic perspective

2014

National audience; We analyse the emergence of scattered residential development, a key characteristic of sprawl. We analyse a 2D urban economic model with neighbourhood interactions among households (social contacts) and with farmers (who produce green amenities). Starting from a cross-shaped road network and CBD, we analytically establish the existence and characteristics of residential leapfrogging that breaks up the compact development of the city. We extend our analysis by numerical experiments based on observed or econometrically estimated parameters. We nd that the shape of built up areas in uences the decision or not to jump over undeveoped land or to stick to the contiguous urban f…

Ré-adaptation et création dans le mythe de Frankenstein (Mary Shelley, James Whale, Kenneth Branagh)

2010

International audience; Le roman de Mary Shelley (1818), les films de James Whale (dès 1931) ou encore de Terence Fisher (dans les années 50 et 60), sont aussi célèbres qu'étudiés, cas d'école pour qui s'intéresse au fantastique, à l'Âge d'or Hollywoodien et à la question de l'adaptation. Tout ou presque a peut-être déjà été écrit sur les avatars du monstre et de son créateur à l'écran : les écarts de James Whale et la création d'un nouveau mythe ; les exubérances de la Hammer ; enfin, le retour au texte dans le film de Kenneth Branagh (1994). Comment expliquer cette profusion d'adaptations du roman de Shelley ? Pourquoi le public accepta-t-il autant de trahisons du roman ? Plusieurs raison…

Predominio de las cheapfakes en redes sociales. Complejidad técnica y funciones textuales de la desinformación desmentida en Argentina durante 2020

2022

Research on disinformation concentrates a growing interest in the design of deepfakes and the possible political, economic and social implications of their viral dissemination on social networks. However, as much or more worrying are the cheapfakes: the hoaxes created by the users themselves through the native features of their mobile devices, the rude manipulation of pre-existing files or the simple addition of text that alters the original meaning of the shared messages. The objective of this research is to analyze the degree of technological complexity of the disinformation that circulated in Argentina during 2020 throughout social networks, as well as the role that the text played in it…

On a numerical solution of the Maxwell equations by discrete exterior calculus

2014

« Un inconnu dans la maison : l’enfant dans ¿ Quién puede matar a un niño ? (Narciso Ibáñez Serrador, 1974) »

2008

This article deals with ¿Quién puede matar a un niño? directed by Narciso Ibáñez Serrador, more famous thanks to his TV film series Historias para no dormir. In this film, children use to play an essential part in the development of a pure fantastic style (in Todorov’s terms), i.e. based on the irruption of unexplainable elements inside a perfectly normal realistic context. As some critics as Rosset have pointed out, the feeling of anguish does arise from such a realistic context, from that otherness within the child, the human being we are more reluctant to fear, the one we hardly view with suspicion Este artículo trata de la obra de Narciso Ibáñez Serrador y, en particular, de uno de sus …