Abstract

Abstract
Dynamic logic with binders D? has been introduced as an institution for the development of reactive systems based on model class semantics. The satisfaction relation of this logic was, however, not abstract enough to enjoy the modal invariance property (bisimilar models should satisfy the same sentences). We recently overcame this problem by proposing an observational satisfaction relation where the equality on states is interpreted by bisimilarity of states. This entailed, however, a price to pay - the satisfaction condition required for institutions was lost. This paper works on this limitation by establishing a behavioural semantics for D? parametric to behavioural structures - families of equivalence relations on the states of each model. Such structures are taken in consideration in the signature category and, in particular, for the definition of signature morphisms. We show that with these changes we get again an institution with a behavioural model class semantics. The framework is instantiated with specific behavioural structures, resulting in the novel Institution of Crucial Actions. © 2017, Springer International Publishing AG.

Abstract
' Renewable energy sources are normally connected to the power grid via power electronic converters. High penetration of these energy sources into the power grid leads to high instability in voltage and frequency. This issue is caused by neglecting the inherent characteristics of synchronous generators i.e., inertia, damping and proper active and reactive power sharing in the structure of the used control technique in the control loop of the interfaced converter between power grid and renewable energy sources. This paper presents a power-based control technique based on a double synchronous controller (DSC) for interfaced converter between the renewable energy sources and the power grid, including an active-reactive power based dynamic equation. Through the proposed DSC, a decoupled control method is performed in which both active and reactive power can be injected from renewable energy sources into the power grid by the interfaced power converter with the inherent features of synchronous power generators. By using the proposed control technique, a stable operation of the power grid can be guaranteed during the integration of large-scale renewable energy sources. Stringent simulation results performed in MATLAB/SIMULINK environment verify the proficiency of the proposed control technique.

Abstract
É discutida a emergência da arte digital e das suas diversas variantes tais como a arte computacional e a média-arte digital. E de como esta forma de expressão artística e cultural se vem afirmando numa contemporaneidade caracterizada pela revolução tecnológica digital. É analisada a natureza da criação e fruição da arte e cultural digital, as práticas artísticas relacionadas e como nestas, o artefacto computacional assume um papel central. Apresentam-se, em contexto, exemplos de artefactos, promovendo-se a sua recensão à luz da arte e cultura digital contemporânea, enquanto se discutem alguns elementos de uma estética dos artefactos computacionais.

Abstract
This article is a case study, based on Participant Observation, which focuses on a digital platform which manages assets. This platform is for sale in different countries, including Portugal and Mozambique. As national cultures and institutions differ from country to country and as this is all the more the case when different continents are at stake, we herein discuss the adaptation of products and services to the cultures and institutions of each environment, for the optimization of sales and product positioning. The data of the case study comes mainly from the experience of one of the authors, who lived in Mozambique for close to two years, linked to the selling there of the digital platform. A review of the existing literature was also performed. The strategic notion of positioning is central to the success of organizations and should differ from context to context, where necessary. Namely, different economic and education conditions lead to distinct behaviours, which have a repercussion on the posture to be adopted for the selling of products. © 2017 AISTI.

Abstract