Monte Carlo Simulation Of Thermal Fluctuations Below The Onset Of Rayleigh-Benard Convection

The density fluctuations below the onset of convection in the Rayleigh-Benard problem are studied with the direct simulation Monte Carlo method. The particle simulation results clearly show the connection between the static correlation functions of fluctuations below the critical Rayleigh number and the flow patterns above the onset of convection for small Knudsen number flows (Kn=0.01 and Kn=0.005). Furthermore, the physical nature for no convection in the Rayleigh-Benard problem under large Knudsen number conditions (Kn>0.028) is explained based on the dynamics of fluctuations.

Improved sampling techniques for the direct simulation Monte Carlo method

The direct simulation Monte Carlo (DSMC) method is a widely used approach for flow simulations having rarefied or nonequilibrium effects. It involves heavily to sample instantaneous values from prescribed distributions using random numbers. In this note, we briefly review the sampling techniques typically employed in the DSMC method and present two techniques to speedup related sampling processes. One technique is very efficient for sampling geometric locations of new particles and the other is useful for the Larsen-Borgnakke energy distribution.

Caballos de monte y carne de potro. Análisis antropológico de un proceso contemporáneo de construcción identitaria, cultural y económica en la Montaña Alavesa

El fenómeno estudiado consiste en una estrategia de desarrollo local emprendida en algunas zonas de montaña de Álava. Se trata de la revitalización sociocultural y económica de las mismas a partir de la recuperación, mejora y refuncionalización de una raza equina autóctona: la yegua de monte alavés. Este proyecto cumple una doble función, la reafirmacion identitaria de la comunidad por un lado y la promoción económica del lugar mediante el producto local por otro. Esta estrategia queda anualmente reafirmada ante la comunidad local y la audiencia gracias al poder evocador de la fiesta. Por ello, se estudia con particular interés "El Día del Caballo en la Montaña Alavesa". A pesar de que tanto la estrategia como la fiesta estudiadas no representan prácticas aisladas dentro del marco rural europeo actual, este caso en concreto posee particularidades que proceden de la propia naturaleza del elemento patrimonializado, el caballo y más concretamente, la carne de potro. Al éxito que la construcción del animal como símbolo local ha tenido para la comunidad local se le contrapone algunos límites culturales como las aversiones alimentarias hacia esta carne en nuestra cultura. A partir del marco teórico ofrecido por la antropología de la alimentación, la antropología del desarrollo y la antropología del patrimonio, la autora investiga de una manera holística el fenómeno propuesto.

Reflexiones sobre la puesta en valor del Monasterio de San Prudencio de Monte Laturce

[ES] Los datos de este registro provienen de la una actividad académica que también aparece descrita en el repositorio y desde donde se puede acceder a otros trabajos relacionados con el Monasterio:

Asymptotic scaling in the two-dimensional O(3) Nonlinear sigma model: a Monte Carlo study on parallel computers

We investigate the 2d O(3) model with the standard action by Monte Carlo simulation at couplings β up to 2.05. We measure the energy density, mass gap and susceptibility of the model, and gather high statistics on lattices of size L ≤ 1024 using the Floating Point Systems T-series vector hypercube and the Thinking Machines Corp.'s Connection Machine 2. Asymptotic scaling does not appear to set in for this action, even at β = 2.10, where the correlation length is 420. We observe a 20% difference between our estimate m/Λ^─_(Ms) = 3.52(6) at this β and the recent exact analytical result . We use the overrelaxation algorithm interleaved with Metropolis updates and show that decorrelation time scales with the correlation length and the number of overrelaxation steps per sweep. We determine its effective dynamical critical exponent to be z' = 1.079(10); thus critical slowing down is reduced significantly for this local algorithm that is vectorizable and parallelizable.

We also use the cluster Monte Carlo algorithms, which are non-local Monte Carlo update schemes which can greatly increase the efficiency of computer simulations of spin models. The major computational task in these algorithms is connected component labeling, to identify clusters of connected sites on a lattice. We have devised some new SIMD component labeling algorithms, and implemented them on the Connection Machine. We investigate their performance when applied to the cluster update of the two dimensional Ising spin model.

Finally we use a Monte Carlo Renormalization Group method to directly measure the couplings of block Hamiltonians at different blocking levels. For the usual averaging block transformation we confirm the renormalized trajectory (RT) observed by Okawa. For another improved probabilistic block transformation we find the RT, showing that it is much closer to the Standard Action. We then use this block transformation to obtain the discrete β-function of the model which we compare to the perturbative result. We do not see convergence, except when using a rescaled coupling β_E to effectively resum the series. For the latter case we see agreement for m/ Λ^─_(Ms) at , β = 2.14, 2.26, 2.38 and 2.50. To three loops m/Λ^─_(Ms) = 3.047(35) at β = 2.50, which is very close to the exact value m/ Λ^─_(Ms) = 2.943. Our last point at β = 2.62 disagrees with this estimate however.