Abstract

Abstract
Formal modelling and verification are critical for managing the inherent complexity of systems with a high degree of variability, such as those designed following the software product line (SPL) paradigm. SPL models tend to be large-the number of products in an SPL can be exponential in the number of features. Modelling these systems poses two main challenges. Firstly, a modular modelling formalism that scales well is required. Secondly, the ability to analyse and verify complex models efficiently is key in order to ensure that all products behave correctly. The choice of a system modelling formalism that is both expressive and well-established is therefore crucial. In this paper we show how SPLs can be modelled in an incremental, modular fashion using a formal method based on Petri nets. We continue our work on Feature Petri Nets, a lightweight extension to Petri nets, by presenting a framework for modularly constructing Feature Petri Nets to model SPLs. © 2011 Springer-Verlag.

Abstract
We study the problem of determination of asset prices in an incomplete market proposing three different but related scenarios. One scenario uses a market game approach whereas the other two are based on risk sharing or regret minimizing considerations. Dynamical schemes modelling the convergence of the buyer's and of the seller's prices to a unique price are proposed.

Abstract
The paper discusses the role of interpretations, understood as multifunctions that preserve and reflect logical consequence, as refinement witnesses in the general setting of p -institutions. This leads to a smooth generalization of the "refinement by interpretation" approach, recently introduced by the authors in more specific contexts. As a second, yet related contribution a basis is provided to build up a refinement calculus of structured specifications in and across arbitrary f-institutions. © C.J. Rodrigues, M.A. Martins, A. Madeira & L.S. Barbosa This work is licensed under the Creative Commons Attribution License.

Abstract
The development of an interferometric optical fiber inclinometer is described in this paper. A weak tapered region is induced in a standard single mode fiber in the vicinity of the cleaved fiber tip, using a standard fusion splicer. In this situation an in-fiber Michelson interferometer is constructed that is sensitive to curvature applied in the tapered region. It is shown that depending on the angular range, fringe visibility and/or peak position depend strongly on the applied curvature enabling low cost dielectric inclinometer to be setup that is suitable for high voltage applications. It is presented an analysis of the sensor response by means of experimental measurements and manipulation of these experimental data through computational simulations. The results coming from the numerical simulations indicate a good performance of the sensor within range of angular variation between 3 and 6 degrees and 10 and 14 degrees. A low cost strategy to interrogate the response of sensor using electrically modulated fiber Bragg gratings, a photodetector and frequency analysis is described. The results presented by this electric interrogation technique show a good sensitivity in the range 3.5 to 5.5 degrees.

Abstract
Wireless applications gradually enter every aspect of our life. Unfortunately, these applications must reuse the same scarce spectrum, resulting in increased interference and limited usability. Cognitive Radio proposes to mitigate this problem by adapting the operational parameters of wireless devices to varying interference conditions. However, it involves an increase in cost. In this paper we examine the economic balance between the added cost and the increased usability in one particular real-life scenario. We focus on the production floor of an industrial installation - where wireless sensors monitor production machinery, and a wireless LAN is used as the data backbone. We examine the effects of implementing dynamic spectrum access by means of ideal RF sensing, and model the benefit in terms of increased reliability and battery lifetime. We estimate the financial cost of interference and the potential gain, and conclude that cognitive radio can bring business gains in real-life applications. © 2011 IFIP International Federation for Information Processing.