Transport on exploding percolation clusters

We propose a simple generalization of the explosive percolation process [Achlioptas et al., Science 323, 1453 (2009)], and investigate its structural and transport properties. In this model, at each step, a set of q unoccupied bonds is randomly chosen. Each of these bonds is then associated with a weight given by the product of the cluster sizes that they would potentially connect, and only that bond among the q-set which has the smallest weight becomes occupied. Our results indicate that, at criticality, all finite-size scaling exponents for the spanning cluster, the conducting backbone, the cutting bonds, and the global conductance of the system, change continuously and significantly with q. Surprisingly, we also observe that systems with intermediate values of q display the worst conductive performance. This is explained by the strong inhibition of loops in the spanning cluster, resulting in a substantially smaller associated conducting backbone.Comment: 4 pages, 4 figure

How to build a brick

AbstractA graph is matching covered if it connected, has at least two vertices and each of its edges is contained in a perfect matching. A 3-connected graph G is a brick if, for any two vertices u and v of G, the graph G-{u,v} has a perfect matching. As shown by Lovász [Matching structure and the matching lattice, J. Combin. Theory Ser. B 43 (1987) 187–222] every matching covered graph G may be decomposed, in an essentially unique manner, into bricks and bipartite graphs known as braces. The number of bricks resulting from this decomposition is denoted by b(G).The object of this paper is to present a recursive procedure for generating bricks. We define four simple operations that can be used to construct new bricks from given bricks. We show that all bricks may be generated from three basic bricks K4, C¯6 and the Petersen graph by means of these four operations. In order to establish this, it turns out to be necessary to show that every brick G distinct from the three basic bricks has a thin edge, that is, an edge e such that (i) G-e is a matching covered graph with b(G-e)=1 and (ii) for each barrier B of G-e, the graph G-e-B has precisely |B|-1 isolated vertices, each of which has degree two in G-e. Improving upon a theorem proved in [M.H. de Carvalho, C.L. Lucchesi, U.S.R. Murty, On a conjecture of Lovász concerning bricks, I, The characteristic of a matching covered graph, J. Combin. Theory Ser. B 85 (2002) 94–136; M.H. de Carvalho, C.L. Lucchesi, U.S.R. Murty, On a conjecture of Lovász concerning bricks, II, Bricks of finite characteristic, J. Combin. Theory Ser. B 85 (2002) 137–180] we show here that every brick different from the three basic bricks has an edge that is thin.A cut of a matching covered graph G is separating if each of the two graphs obtained from G by shrinking the shores of the cut to single vertices is also matching covered. A brick is solid if it does not have any nontrivial separating cuts. Solid bricks have many interesting properties, but the complexity status of deciding whether a given brick is solid is not known. Here, by using our theorem on the existence of thin edges, we show that every simple planar solid brick is an odd wheel

Prediction of Evaporator Frosting in Household Refrigerators Subjected to Periodic Door Opening

This paper describes a quasi-steady-state simulation model for predicting the transient behavior of a household refrigerator subjected to periodic door opening. A semi-empirical steady-state sub-model was developed for the refrigeration loop, and a transient sub-model was devised to predict the energy and mass transfer into and within the refrigerated compartments as well as the evaporator frosting. The key empirical heat and mass transfer parameters required by the model were derived from a set of experiments carried out in a climate-controlled chamber. In general, it was found that the model predictions followed closely the experimental trends for the power consumption (deviations within ±10%) and for the compartment temperatures (deviations within ±2 K)

Numerical study of fatigue crack initiation and propagation on optimally designed cruciform specimens

A new generation of smaller and more efficient biaxial fatigue testing machines has arrived on the market. Using electrical motors these machines are not able to achieve the higher loads their hydraulic counterparts can, and therefore the cruciform specimen needs to be optimized Following the authors previous work, several different optimal specimens' configurations were produced, using the base material sheet thickness as the main design variable. Every design variable was optimized in order to produce the highest stress level on the specimen center, while the stress distribution is still uniform on a 1 mm radius of the specimen center. Also it was guaranteed that the stress level on the specimen arms was always considerably lower, in order to achieve failure at the specimen center. In this paper traditional criteria like Findley, Brown-Miller, Fatemi-Socie, Smith, Watson e Topper (SWT), Liu I and Chu were considered to determine crack initiation direction for several loads in this biaxial in-plane specimens. In order to understand the fatigue propagation behavior, the stress intensity factors for mode I and mode II was determined for different cracks introduced on the geometry. Several crack and loading parameters were studied, including the starting crack length and angle, and different loading paths. Several biaxial loads were applied to the model, including 30, 45, 60, 90 and 180 out-of-phase angles.info:eu-repo/semantics/publishedVersio

Biologia com humor: utilização de charges na divulgação científica

Anais do 3° Encontro Nacional de Jogos e Atividades Lúdicas no Ensino de Química, Física e Biologia (Jalequim - Level III) - Núcleo de Desenvolvimento de Pesquisas em Ensino de Química/Ciências da UNILA (NuDDEQ)O campo das Ciências Biológicas apresenta linguajar e conceitos que, muitas vezes, soam como estranhos ao público em geral. Tal aspecto pode contribuir para um afastamento das pessoas em relação a esta área do conhecimento (SASSERON & CARVALHO, 2011). Desta maneira, é interessante se pensar estratégias de aproximação do linguajar biológico com o cotidiano das pessoas, contribuindo assim para a divulgação científica. Entre as várias possibilidades de estratégias de divulgação científica, o presente trabalho optou por trabalhar a mesma relacionando-a com o humor, utilizando-se charges