Search results for "Scheme"
showing 10 items of 527 documents
Chiral structure of the Roper resonance using complex-mass scheme
2010
The pole mass and the width of the Roper resonance are calculated as functions of the pion mass in the framework of low-energy effective field theory of the strong interactions. We implement a systematic power-counting procedure by applying the complex-mass scheme.
The classical statistical mechanics of Frenkel-Kontorova models
1995
The scaling properties of the free energy, specific heat, and mean spacing are calculated for classical Frenkel-Kontorova models at low temperature, in three regimes: near the integrable limit, the anti-integrable limit, and the sliding-pinned transition (“transition by breaking of analyticity”). In particular, the renormalization scheme given in previous work for ground states of Frenkel-Kontorova models is extended to nonzero-temperature Gibbs states, and the hierarchical melting phenomenon of Vallet, Schilling, and Aubry is put on a rigorous footing.
Masclet: a new multidimensional AMR cosmological code
2004
A new cosmological multidimensional hydrodynamic and N-body code based on an Adaptive Mesh Refinement scheme is described and tested. The hydro part is based on modern high-resolution shock-capturing techniques, whereas N-body approach is based on a Particle Mesh method. The code has been specifically designed for cosmological applications.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html
On the numerical scheme employed in gyrotron interaction simulations
2012
We report on the influence of the numerical scheme employed in gyrotron interaction simulations. Results obtained with the Crank-Nicolson scheme are compared with those obtained with the Backward Time – Centred Space (BTCS) fully implicit scheme. We present realistic cases where, for discretisation parameters in the range usually used in gyrotron simulations, the results can be very different. Hence, the numerical scheme used can be responsible for obscuring the underlying physics if its convergence is not tested carefully.
The methods of XLOOPS An introduction to parallel space techniques
1997
Abstract The package XLOOPS presented in this workshop relies on the application of parallel space techniques. We introduce these techniques covering the following topics: • - The generation of integral representations for massive two-loop diagrams. • - The treatment of tensor structures. • - The handling of the γ-algebra in this scheme. • - The separation of UV and IR divergences in analytic expressions. We present two-loop examples taken from Standard Model calculations.
A numerical study of postshock oscillations in slowly moving shock waves
2003
Abstract Godunov-type methods and other shock capturing schemes can display pathological behavior in certain flow situations. This paper discusses the numerical anomaly associated to slowly moving shocks. We present a series of numerical experiments that illustrate the formation and propagation of this pathology, and allows us to establish some conclusions and question some previous conjectures for the source of the numerical noise. A simple diagnosis on an explicit Steger-Warming scheme shows that some intermediate states in the first time steps deviate from the true direction and contaminate the flow structure. A remedy is presented in the form of a new flux split method with an entropy i…
Unraveling the nature of universal dynamics in $O(N)$ theories
2020
Many-body quantum systems far from equilibrium can exhibit universal scaling dynamics which defy standard classification schemes. Here, we disentangle the dominant excitations in the universal dynamics of highly-occupied $N$-component scalar systems using unequal-time correlators. While previous equal-time studies have conjectured the infrared properties to be universal for all $N$, we clearly identify for the first time two fundamentally different phenomena relevant at different $N$. We find all $N\geq3$ to be indeed dominated by the same Lorentzian ``large-$N$'' peak, whereas $N=1$ is characterized instead by a non-Lorentzian peak with different properties, and for $N=2$ we see a mixture …
A Second Order Accurate Kinetic Relaxation Scheme for Inviscid Compressible Flows
2013
In this paper we present a kinetic relaxation scheme for the Euler equations of gas dynamics in one space dimension. The method is easily applicable to solve any complex system of conservation laws. The numerical scheme is based on a relaxation approximation for conservation laws viewed as a discrete velocity model of the Boltzmann equation of kinetic theory. The discrete kinetic equation is solved by a splitting method consisting of a convection phase and a collision phase. The convection phase involves only the solution of linear transport equations and the collision phase instantaneously relaxes the distribution function to an equilibrium distribution. We prove that the first order accur…
Study and construction of the quasi-linear subdivision schemes over bi-regular meshs
2012
Subdivision schemes are commonly used to generate a smooth shape from a much more coarseone. The reverse subdivision is designed to describe a high resolution mesh from a coarse one. Bothof these tools are used in numerous graphical modelisation domains. In this thesis, we focused ontwo distinct aspects: on one hand the construction of quasi-linear subdivision schemes and on theother hand the construction of reverse quad/triangle subdivision schemes. The work, presented inthe context of the subdivision, describes the construction of a new type of subdivision schemes, andtheirs applications to solve some problems coming from the application of linear subdivision schemes.The work presented in…
Up-to-date report on the distribution ofHelianthemum lippii(Cistaceae) in Italy
2015
An up-to-date report on the distribution of Helianthemum lippii in Italy is provided also on the basis of the findings by Lojacono-Pojero in 1889 who reported the existence of a relic population in Sicily (southern Italy), which is now thought to be extinct because of human disturbance. Field excursions permitted to confirm the locus classicus reported by Lojacono-Pojero as the other Sicilian localities that have been reported more recently. Based on a careful analysis of the literature the presence of H. lippii is currently excluded in Calabria and Apulia. The main causes that threaten the habitat of H. lippii in Sicily are pointed out according to IUCN Threats Classification Scheme.