Asteroseismic Theory of Rapidly Oscillating Ap Stars

This paper reviews some of the important advances made over the last decade concerning theory of roAp stars.Comment: 9 pages, 5 figure

The Geometry of Entanglement Sudden Death

In open quantum systems, entanglement can vanish faster than coherence. This phenomenon is usually called sudden death of entanglement. In this paper sudden death of entanglement is discussed from a geometrical point of view, in the context of two qubits. A classification of possible scenarios is presented, with important known examples classified. Theoretical and experimental construction of other examples is suggested as well as large dimensional and multipartite versions of the effect.Comment: 6 pages, 2 figures, references added, initial paragraph corrected, sectioning adopted, some parts rewritten; accepted by New J. Phy

Tomographic Characterization of Three-Qubit Pure States with Only Two-Qubit Detectors

A tomographic process for three-qubit pure states using only pairwise detections is presented.Comment: 3 pages; revtex4; v2: the focus on tomography was emphasized and the experimental procedure detailed; v3: the text was improved in clarity, some mistakes were correcte

Water network design using a multiobjective real options framework

This is the final version of the article. Available from the publisher via the DOI in this record.Water distribution networks (WDNs) are an essential element of urban infrastructure. To achieve a good level of performance, the traditional design of WDNs based on expected future conditions should be replaced by a flexible design, using real options (ROs), that accounts for uncertainty by taking a broader view of possible future options. This work proposes a multiobjective ROs framework that sets out to reduce costs, minimize hydraulic pressure deficiency, and a third objective for minimizing carbon emissions. A multiobjective simulated annealing algorithm is used to identify the Pareto-optimal solutions, thus enabling a tradeoff analysis between solutions. These trade-offs show that a low pressure deficit solution is achieved by increasing investment at a much faster rate after a certain pressure deficit threshold (60 m). Also, the pressure deficits can only be reduced by increasing carbon emissions. Finally, this work also emphasizes the importance of including carbon emissions as a specific objective by comparing the results of the proposed model and another one that did not cover the environmental objective. The results show that it is possible to reduce CO2 for the same level of capital expenditure or the same level of network pressure deficits if carbon emissions are minimized in the optimization process.This study had the support of Fundac¸ao para a Ci ˜ encia e ˆ Tecnologia (FCT), through the Strategic Project UID/MAR/ 04292/2013 granted to MARE

Study of solids conveying in single screw extruders based on flow dynamics and structure of solid pellets

Flow of granular matter is presently a subject of extensive research, due to the characteristics of this type of systems (e.g., dilatancy, segregation, arching, clustering) and relevance to various application areas, such as civil construction, agriculture, food processing, geophysics, pharmacology [1, 2]. The plasticating process in single screw polymer extrusion is one of the areas where this research can help to increase the existing knowledge. In the initial turns of an Archimedes-type screw, loose pellets are conveyed forward. However, traditional analyses assume the movement of an elastic solid plug at constant velocity. This work follows previous efforts to predict the characteristics of this flow using the Discrete Element Method (DEM) [3, 4]. Two boundary conditions are considered: a) open-discharge, implying that no compaction of the solids occurs and b) close-discharge, leading to a pressure increase. The dynamics and the structure of the flow were studied by computing the cross- and down channel velocity profiles, the coordination number distribution, the output rate, the residence time distribution and the density profile, as a function of the friction force grain-wall, screw speed and pellet size. The model is able to capture the process of plug formation towards the discharge, and its predictions provide an insight into possible flow fluctuations