Time scale competition leading to fragmentation and recombination transitions in the coevolution of network and states

We study the co-evolution of network structure and node states in a model of multiple state interacting agents. The system displays two transitions, network recombination and fragmentation, governed by time scales that emerge from the dynamics. The recombination transition separates a frozen configuration, composed by disconnected network components whose agents share the same state, from an active configuration, with a fraction of links that are continuously being rewired. The nature of this transition is explained analytically as the maximum of a characteristic time. The fragmentation transition, that appears between two absorbing frozen phases, is an anomalous order-disorder transition, governed by a crossover between the time scales that control the structure and state dynamics.Comment: 5 pages, 5 figures, figures 2 and 4 changed, tile changed, to be published in PR

VLBA determination of the distance to nearby star-forming regions I. The distance to T Tauri with 0.4% accuracy

In this article, we present the results of a series of twelve 3.6-cm radio continuum observations of T Tau Sb, one of the companions of the famous young stellar object T Tauri. The data were collected roughly every two months between September 2003 and July 2005 with the Very Long Baseline Array (VLBA). Thanks to the remarkably accurate astrometry delivered by the VLBA, the absolute position of T Tau Sb could be measured with a precision typically better than about 100 micro-arcseconds at each of the twelve observed epochs. The trajectory of T Tau Sb on the plane of the sky could, therefore, be traced very precisely, and modeled as the superposition of the trigonometric parallax of the source and an accelerated proper motion. The best fit yields a distance to T Tau Sb of 147.6 +/- 0.6 pc. The observed positions of T Tau Sb are in good agreement with recent infrared measurements, but seem to favor a somewhat longer orbital period than that recently reported by Duchene et al. (2006) for the T Tau Sa/T Tau Sb system.Comment: 24 pages, 3 pages, AASTEX format, accepted for publication in Ap

Dynamic analysis using finite elements to calculate the critical wear section of the contact wire in suburban railway overhead conductor rails

The purpose of this study is to determine the critical wear levels of the contact wire of the catenary on metropolitan lines. The study has focussed on the zones of contact wire where localised wear is produced, normally associated with the appearance of electric arcs. To this end, a finite element model has been developed to study the dynamics of pantograph-catenary interaction. The model includes a zone of localised wear and a singularity in the contact wire in order to simulate the worst case scenario from the point of view of stresses. In order to consider the different stages in the wire wear process, different depths and widths of the localised wear zone were defined. The results of the dynamic simulations performed for each stage of wear let the area of the minimum resistant section of the contact wire be determined for which stresses are greater than the allowable stress. The maximum tensile stress reached in the contact wire shows a clear sensitivity to the size of the local wear zone, defined by its width and depth. In this way, if the wear measurements taken with an overhead line recording vehicle are analysed, it will be possible to calculate the potential breakage risk of the wire. A strong dependence of the tensile forces of the contact wire has also been observed. These results will allow priorities to be set for replacing the most critical sections of wire, thereby making maintenance much more efficient. The results obtained show that the wire replacement criteria currently borne in mind have turned out to be appropriate, although in some wear scenarios these criteria could be adjusted even more, and so prolong the life cycle of the contact wire

Statistical analysis of soy cultivation in Argentina

Argentina are analyzed. The main objective is to obtain information that will be useful for the analysis of the environmental consequences of the progress of this crop in the country. This has been made by a descriptive statistical analysis and a factor analysis was used to identify factors which characterize the soybean crop and also a classification or clustering between provinces with similar characteristics. The information parameters studied were: the tendency and dispersion measures for soybean yield of 15 provinces in which it was grown between the 2001/02 and 2010/11 or from 2001/02 to 2010/11; the correlations between area harvested acreage, seeded area, production and performance, and the factors that bind some variables that characterize the soybean crop that allows a grouping between provinces with similar characteristics. Analyses were performed by using data obtained from: 1) MinAgri (last 10 seasons) b) 2001 National Census c) CNA 2002. From a group of variables: region extension (ha); population density 2001; population of the region in 2001; NBI 2001, literate people older than 10 years 2001; illiterate people older than 10 years 2001; permanent workers in the farming sector 2002; seeded area (ha) 2002; cultivated area of oily plants (ha) 2002; tractors 2002; harvesters 2002; seeded area (ha) 2001/02; harvested area (ha) 2001/02; production (Tn) 2001/02.Fil: Miranda del Fresno, Ma. Carolina. Universidad Nacional del Centro de la Provincia de Buenos Aires. Centro de Investigaciones y Estudios Ambientales; ArgentinaFil: Villacampa, Y.. Universidad de Alicante. Departamento de Qui­mica Orgánica; EspañaFil: Navarro Gonzalez, F. J.. Universidad de Alicante. Departamento de Qui­mica Orgánica; EspañaFil: Sastre Vazquez, P.. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Agronomia; Argentin

A Deep Learning Approach to Estimate Multi-Level Mental Stress from EEG using Serious Games

Stress is revealed by the inability of individuals to cope with their environment, which is frequently evidenced by a failure to achieve their full potential in tasks or goals. This study aims to assess the feasibility of estimating the level of stress that the user is perceiving related to a specific task through an electroencephalograpic (EEG) system. This system is integrated with a Serious Game consisting of a multi-level stress driving tool, and Deep Learning (DL) neural networks are used for classification. The game involves controlling a vehicle to dodge obstacles, with the number of obstacles increasing based on complexity. Assuming that there is a direct correlation between the difficulty level of the game and the stress level of the user, a recurrent neural network (RNN) with a structure based on gated recurrent units (GRU) was used to classify the different levels of stress. The results show that the RNN model is able to predict stress levels above current state-of-the-art with up to 94% accuracy in some cases, suggesting that the use of EEG systems in combination with Serious Games and DL represents a promising technique in the prediction and classification of mental stress levels

Steel heat treating: Mathematical modelling and numerical simulation of a problem arising in the automotive industry

We describe a mathematical model for the industrial heating and cooling processes of a steel workpiece representing the steering rack of an automobile. The goal of steel heat treating is to provide a hardened surface on critical parts of the workpiece while keeping the rest soft and ductile in order to reduce fatigue. The high hardness is due to the phase transformation of steel accompanying the rapid cooling. This work takes into account both heating-cooling stage and viscoplastic model. Once the general mathematical formulation is derived, we can perform some numerical simulations

Interplay of zero-field splitting and excited state geometry relaxation in fac-Ir(ppy)3

The lowest energy triplet state, T-1, of organometallic complexes based on iridium(III) is of fundamental interest, as the behavior of molecules in this state determines the suitability of the complex for use in many applications, e.g., organic light-emitting diodes. Previous characterization of T-1 in fac-Ir(ppy)(3) suggests that the trigonal symmetry of the complex is weakly broken in the excited state. Here we report relativistic time dependent density functional calculations of the zero-field splitting (ZFS) of fac-Ir(ppy)(3) in the ground state (S-0) and lowest energy triplet (T-1) geometries and at intermediate geometries. We show that the energy scale of the geometry relaxation in the T-1 state is large compared to the ZFS. Thus, the natural analysis of the ZFS and the radiative decay rates, based on the assumption that the structural distortion is a small perturbation, fails dramatically. In contrast, our calculations of these quantities are in good agreement with experiment