Transient Nucleation near the Mean-Field Spinodal

Nucleation is considered near the pseudospinodal in a one-dimensional $\phi^4$ model with a non-conserved order parameter and long-range interactions. For a sufficiently large system or a system with slow relaxation to metastable equilibrium, there is a non-negligible probability of nucleation occurring before reaching metastable equilibrium. This process is referred to as transient nucleation. The critical droplet is defined to be the configuration of maximum likelihood that is dynamically balanced between the metastable and stable wells. Time-dependent droplet profiles and nucleation rates are derived, and theoretical results are compared to computer simulation. The analysis reveals a distribution of nucleation times with a distinct peak characteristic of a nonstationary nucleation rate. Under the quench conditions employed, transient critical droplets are more compact than the droplets found in metastable equilibrium simulations and theoretical predictions.Comment: 7 Pages, 5 Figure

The two-echelon capacitated vehicle routing problem: models and math-based heuristics

Multiechelon distribution systems are quite common in supply-chain and logistics. They are used by public administrations in their transportation and traffic planning strategies, as well as by companies, to model own distribution systems. In the literature, most of the studies address issues relating to the movement of flows throughout the system from their origins to their final destinations. Another recent trend is to focus on the management of the vehicle fleets required to provide transportation among different echelons. The aim of this paper is twofold. First, it introduces the family of two-echelon vehicle routing problems (VRPs), a term that broadly covers such settings, where the delivery from one or more depots to customers is managed by routing and consolidating freight through intermediate depots. Second, it considers in detail the basic version of two-echelon VRPs, the two-echelon capacitated VRP, which is an extension of the classical VRP in which the delivery is compulsorily delivered through intermediate depots, named satellites. A mathematical model for two-echelon capacitated VRP, some valid inequalities, and two math-heuristics based on the model are presented. Computational results of up to 50 customers and four satellites show the effectiveness of the methods developed

Global aspects of gravitomagnetism

We consider global properties of gravitomagnetism by investigating the gravitomagnetic field of a rotating cosmic string. We show that although the gravitomagnetic field produced by such a configuration of matter vanishes locally, it can be detected globally. In this context we discuss the gravitational analogue of the Aharonov-Bohm effect.Comment: 10 pages - Typeset using REVTE

Comments on "There is no axiomatic system for the quantum theory"

In a recent paper, Nagata [1] claims to derive inconsistencies from quantum mechanics. In this paper, we show that the inconsistencies do not come from quantum mechanics, but from extra assumptions about the reality of observables

Uso da ressonância magnética nuclear de baixo campo na determinação rápida do teor de umidade em madeiras.

Neste trabalho é apresentada uma recomendação da utilização da técnica de ressonância magnética nuclear (RMN) de baixo campo como método alternativo na determinação rápida da umidade em madeiras. Este método utiliza o espectrômetro de RMN desenvolvido pela Embrapa Instrumentação Agropecuária e transferido para a Empresa GIL Equipamentos Especiais.bitstream/CNPDIA/9437/1/RT12_99.pd

Experimental characterization of the flexural behaviour of steel fibre reinforced concrete according to RILEM TC 162-TDF recommendations

The post-cracking energy absorption capacity is the concrete property most benefited by steel fibre reinforcement, usually designated by toughness. Different test set-ups, test procedures and parameters have been proposed to evaluate the toughness of the steel fibre reinforced concrete (SFRC), but none of them has received a general acceptation by scientific and technical communities. As a consequence, designers put some reserves on the use of SFRC, because they are not confident on the design practice to be adopted, resulting in the exclusion of SFRC in applications where it could be the most suitable solution. In the last years RILEM TC 162 – TDF has published documents where recommendations for characterizing and designing SFRC structures are proposed. A general acceptation of these recommendations can be only taken if they are deeply analysed and checked by a large number of research centres. This work intends to give some contribution for this analysis. It has also the purpose of evaluating the influence of the fibre content, percentage of cement replaced by fly ash and SFRC age on the post-cracking behaviour of the SFRC, under the experimental framework recommended by RILEM TC 162 – TDF.Fundação para a Ciência e a Tecnologia (FCT) - POCTI/34793/99. "Cost competitive steel fibre reinforced concrete for industrial pavements“Pisonort – Pavimentos industriais LdaSeci

Joints in pavements of industrial buildings

Os pavimentos de edifícios industriais são das obras de engenharia civil em que ocorrem maior número de patologias. Tal deve-se a deficiente empenho dos intervenientes na concepção, projecto e construção deste tipo de estruturas, muitas vezes associado ao sentimento de que a não verificação dos estados limites de utilização e últimos não está directamente ligado à ocorrência de acidentes trágicos. Porém, é reconhecido que, em muitos casos, o deficiente funcionamento deste tipo de estruturas conduz a prejuízos económicos significativos e, por vezes, a acidentes envolvendo seres humanos. De entre as patologias ocorridas em pavimentos industriais, as devidas directa ou indirectamente com juntas, são as mais correntes. Um deficiente traçado de juntas pode conduzir, em caso limite, à inutilização do pavimento, sendo a reabilitação deste bastante onerosa. Este trabalho é dedicado à temática das juntas em pavimentos de edifícios industriais, desde a sua concepção, traçado até ao dimensionamento de elementos de transferência de carga entre painéis adjacentes à junta.Pavements of industrial floors are one of the Civil Engineering realizations where higher number of pathologies occurred. This is caused by the deficient attitude of the intervenients in the conception, design, execution and quality control of this type of structural application. This behavior is related to the idea that a tragic accident will not occur even if the serviceability and ultimate limit analysis are not accomplished in the design practice. In several cases, however, a pavement with deficient operation leads to significant economical loses, and, sometimes to human injuries