6,348 research outputs found
Classical Radiation Reaction in Particle-In-Cell Simulations
Under the presence of ultra high intensity lasers or other intense
electromagnetic fields the motion of particles in the ultrarelativistic regime
can be severely affected by radiation reaction. The standard particle-in-cell
(PIC) algorithms do not include radiation reaction effects. Even though this is
a well known mechanism, there is not yet a definite algorithm nor a standard
technique to include radiation reaction in PIC codes. We have compared several
models for the calculation of the radiation reaction force, with the goal of
implementing an algorithm for classical radiation reaction in the Osiris
framework, a state-of-the-art PIC code. The results of the different models are
compared with standard analytical results, and the relevance/advantages of each
model are discussed. Numerical issues relevant to PIC codes such as resolution
requirements, application of radiation reaction to macro particles and
computational cost are also addressed. The Landau and Lifshitz reduced model is
chosen for implementation.Comment: 12 pages, 8 figure
Pullback attractors for a singularly nonautonomous plate equation
We consider the family of singularly nonautonomous plate equation with
structural damping in a bounded domain , with Navier
boundary conditions. When the nonlinearity is dissipative we show that this
problem is globally well posed in and has a
family of pullback attractors which is upper-semicontinuous under small
perturbations of the damping
Full-scale ab initio 3D PIC simulations of an all-optical radiation reaction configuration at
Using full-scale 3D particle-in-cell simulations we show that the radiation
reaction dominated regime can be reached in an all optical configuration
through the collision of a 1 GeV laser wakefield accelerated (LWFA)
electron bunch with a counter propagating laser pulse. In this configuration
radiation reaction significantly reduces the energy of the particle bunch, thus
providing clear experimental signatures for the process with currently
available lasers. We also show that the transition between classical and
quantum radiation reaction could be investigated in the same configuration with
laser intensities of
Particle Merging Algorithm for PIC Codes
Particle-in-cell merging algorithms aim to resample dynamically the
six-dimensional phase space occupied by particles without distorting
substantially the physical description of the system. Whereas various
approaches have been proposed in previous works, none of them seemed to be able
to conserve fully charge, momentum, energy and their associated distributions.
We describe here an alternative algorithm based on the coalescence of N massive
or massless particles, considered to be close enough in phase space, into two
new macro-particles. The local conservation of charge, momentum and energy are
ensured by the resolution of a system of scalar equations. Various simulation
comparisons have been carried out with and without the merging algorithm, from
classical plasma physics problems to extreme scenarios where quantum
electrodynamics is taken into account, showing in addition to the conservation
of local quantities, the good reproducibility of the particle distributions. In
case where the number of particles ought to increase exponentially in the
simulation box, the dynamical merging permits a considerable speedup, and
significant memory savings that otherwise would make the simulations impossible
to perform
Traditional wooden houses in Maringá (Brazil): ICT in planning research
In many cities, the examples of traditional architecture are being replaced by contemporary buildings, without any strategies in order to preserve a specific period of the urban and housing histories. These legacies are witnesses of particular features in terms of local communities, societies, political environments, urban morphologies or architectural languages. In this sense, this article presents the case study of the traditional wooden houses in the city of Maringá in Paraná (Brazil). There is a set of buildings which still remain among the existing urban fabric. However, every year some of them are destroyed in order to give room for new ways of designing the city. The methodological approach is based on the ICT (information and communication technologies) as a tool to study the features of these traditional wooden buildings.info:eu-repo/semantics/publishedVersio
Cross-leg flap after free flap failure: a case report
The cross-leg flap is a technique that has been used for a long time to address defects in the distal third of the leg. Currently, the gold standard for these defects is free flap reconstruction. However, the success of microsurgery is not always guaranteed due to a wide range of extrinsic and intrinsic factors. In this study, we present the use of a cross-leg flap as an alternative in the case of free flap failure, performed in the plastic and reconstructive surgery department of the General Hospital of Mexico. The cross-leg flap represents a reliable, simple, and effective alternative when free flaps are not suitable or as a rescue in case of their failure, either due to extrinsic or patient-related causes.
An analysis of the potentialities of portuguese vernacular architecture to improve energy efficiency
Vernacular architecture is characterised by a type of formal expression that has been developed in response to a number of factors â climatic, lithologic, cultural and economic â characterising the local area or region. In its various forms, a range of techniques has been employed in different regions to mitigate the effects of climate. Despite the fact that Portugal is a small country, it has a territory full of contrasts, which gave origin to many different architectural manifestations. The approaches adopted in the design and construction of vernacular buildings have the potential for further development and could be adapted in response to contemporary needs. In the future, a blend of tradition and modernity should be aimed at in order to develop a new form of aesthetics and functional construction. Portuguese vernacular architecture is associated with a fund of valuable knowledge that should be studied and aligned with the principles of sustainability. In this paper, is presented the climatic contrast between the northern and southern parts of Portugal and the relation with the purpose of different passive solar techniques used in vernacular architecture to provide comfort. The focus is on the effectiveness of passive cooling techniques (e.g. high thermal inertia, the use of light colours and patios), and the findings of a case study in which the thermal performance during the summer of a vernacular residential building located in the south of Portugal are presented. In the context of the current global drive for clean energy and sustainable buildings, much can be learned from a review of past experience in order to provide an understanding of such forms of construction, which are an intrinsic feature of specific places and have evolved over time in the face of a lack of resources
- …