441 research outputs found
Temperature-extended Jarzynski relation: Application to the numerical calculation of the surface tension
We consider a generalization of the Jarzynski relation to the case where the
system interacts with a bath for which the temperature is not kept constant but
can vary during the transformation. We suggest to use this relation as a
replacement to the thermodynamic perturbation method or the Bennett method for
the estimation of the order-order surface tension by Monte Carlo simulations.
To demonstrate the feasibility of the method, we present some numerical data
for the 3D Ising model
Comparison of laboratory and field electrical resistivity measurements of a gypsum rock for mining prospection applications
Interaction effects in the spectrum of the three-dimensional Ising model
The two-point correlation functions of statistical models show in general
both poles and cuts in momentum space. The former correspond to the spectrum of
massive excitations of the model, while the latter originate from interaction
effects, namely creation and annihilation of virtual pairs of excitations. We
discuss the effect of such interactions on the long distance behavior of
correlation functions in configuration space, focusing on certain time-slice
operators which are commonly used to extract the spectrum. For the 3D Ising
model in the scaling region of the broken-symmetry phase, a one-loop
calculation shows that the interaction effects on time-slice correlations is
non negligible for distances up to a few times the correlation length, and
should therefore be taken into account when analysing Monte Carlo data.Comment: 10 pages, LaTeX file + 1 ps figure, uses axodraw.st
Mechanical properties of microcrystalline branching selenite gypsum samples and influence of constituting factors
The high sedimentological variability of gypsum rocks has the effect that a univocal characterization of this material is not easy to establish. This is particularly true from the geomechanical point of view: when the mechanical properties of gypsum rocks are requested, it is therefore necessary to undertake detailed characterization analyses. Common facies of gypsum was observed in the Upper Miocene evaporitic succession (Messinian Salinity Crisis) within the whole Mediterranean Basin. In this work, mechanical tests were conducted on a site-specific facies, represented by the microcrystalline branching selenite. The tested samples came from the Monferrato area (northwestern Italy). Uniaxial compressive strength (UCS) tests were performed in order to obtain reference mechanical parameters. More rapid and economic point load test (PLT) and ultrasonic pulse velocity (UPV) measurements were additionally performed to verify their applicability as complementary/alternative methods for site characterization. Rock-type specific PLT-UCS and UPV-UCS relationships were established. A wide dispersion of the mechanical parameters was observed due to the heterogeneities of the studied material. Consequently, compositional, textural and microstructural observations on selected samples were performed. Two main material classes were recognized based on average grain size and total gypsum content, underlining the significant influence of the grain sorting on the measured mechanical properties
PRELIMINARY EVALUATION OF GEOELECTRICAL METHODS FOR THE QUANTIFICATION OF VOLUMETRIC BLOCK PROPORTION (VBP) OF MÉLANGES
The Online Error Control and Handling of the ALICE Pixel Detector
The SPD forms the two innermost layers of the ALICE Inner Tracking System (ITS) [1]. The basic building block of the SPD is the half-stave, the whole SPD barrel being made of 120 half-staves with a total number of 9.8 x 106 readout channels. Each half-stave is connected via three optical links to the off-detector electronics made of FPGA based VME readout cards (Routers). The Routers and their mezzanine cards provide the zero-suppression, data formatting and multiplexing and the link to the DAQ [2] system. This paper presents the hardware and software tools developed to detect and process any errors, at the level of the Router, originating from either front-end electronics, trigger sequences, DAQ or the off-detector electronics. The on-line error handling system automatically transmits this information to the Detector Control System and to the dedicated ORACLE database for further analysis
Critical exponents for higher-representation sources in 3D SU(3) gauge theory from CFT
We establish an exact mapping between the multiplication table of the
irreducible representations of SU(3) and the fusion algebra of the
two-dimensional conformal field theory in the same universality class of 3D
SU(3) gauge theory at the deconfining point. In this way the Svetitsky-Yaffe
conjecture on the critical behaviour of Polyakov lines in the fundamental
representation naturally extends to whatever representation one considers.
As a consequence, the critical exponents of the correlators of these Polyakov
lines are determined. Monte Carlo simulations with sources in the symmetric
two-index representation, combined with finite-size scaling analysis, compare
very favourably with these predictions.Comment: 15 pages, 2 figure
The stability of the O(N) invariant fixed point in three dimensions
We study the stability of the O(N) fixed point in three dimensions under
perturbations of the cubic type. We address this problem in the three cases
by using finite size scaling techniques and high precision Monte
Carlo simulations. It is well know that there is a critical value
below which the O(N) fixed point is stable and above which the cubic fixed
point becomes the stable one. While we cannot exclude that , as recently
claimed by Kleinert and collaborators, our analysis strongly suggests that
coincides with 3.Comment: latex file of 18 pages plus three ps figure
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