Three-phase current-source shunt active power filter with solar photovoltaic grid interface

This paper presents the proposal of a three phase current source shunt active power filter (CS-SAPF) with photovoltaic grid interface. The proposed system combines the compensation of reactive power and harmonics with the injection of energy from a solar photovoltaic array into the electrical power grid. The proposed equipment presents the advantage of giving good use to the current source inverter, even when the solar photovoltaic array is not producing energy. The paper describes the control system of the CS SAPF, the energy injection control strategy, and the current harmonics and power factor compensation strategy. Simulation results to assess the performance of the proposed system are also presented.

Análise da disponibilidade de investimento em projetos de reabilitação portugueses

The importance of implementing sustainable practices in buildings is duly proved and understood by the majority of the population. However, its implementation is not yet a reality. Some studies have been performed with the goal of understand this lack of use of sustainable solutions, among building sector stakeholders. The conclusion is that one of the main factors contributing to this is related with economic constraints. Several studies have proven that many sustainable practices correspond to minor costs than traditional practices in a life cycle perspective. However, the building sector stakeholders are not aware of this and do not implement sustainable practices commonly. In this paper a costâ benefit methodology willing to cross this barrier and promote the sustainable practices implementation is presented.

The group inverse of a product

In this paper, we characterize the existence and give an expression of the group inverse of a product of two regular elements by means of a ring unit.

Further results on the inverse along an element in semigroups and rings

In this paper, we introduce a new notion in a semigroup $S$ as an extension of Mary's inverse. Let $a,d\in S$. An element $a$ is called left (resp. right) invertible along $d$ if there exists $b\in S$ such that $bad=d$ (resp. $dab=b$) and $b\leq_\mathcal{L}d$ (resp. $b\leq_\mathcal{R}d$). An existence criterion of this type inverse is derived. Moreover, several characterizations of left (right) regularity, left (right) $\pi$-regularity and left (right) $*$-regularity are given in a semigroup. Further, another existence criterion of this type inverse is given by means of a left (right) invertibility of certain elements in a ring. Finally we study the (left, right) inverse along a product in a ring, and, as an application, Mary's inverse along a matrix is expressed.

The inverse along a product and its applications

In this paper, we study the recently defined notion of the inverse along an element. An existence criterion for the inverse along a product is given in a ring. As applications, we present the equivalent conditions for the existence and expressions of the inverse along a matrix.

Competência judiciária na União Europeia

O presente texto procura, fundamentalmente, analisar o âmbito de aplicação do Regulamento (UE) n.º 1215/2012, do Parlamento Europeu e do Conselho, de 12/12/2012, relativo à competência judiciária, ao reconhecimento e à execução de decisões em matéria civil e comercial, circunscrevendo-se essa análise à abordagem da competência judiciária na União Europeia. No prosseguimento desse desiderato, são analisados os âmbitos temporal, objetivo e subjetivo do regulamento, sem se descurar as problemáticas da competência exclusiva e convencional, bem como da litispendência europeia. Procurou-se igualmente, ainda que de forma genérica, assinalar as principais inovações do Regulamento (UE) n.º 1215/2012 no âmbito da competência judiciária, por contraposição ao Regulamento (CE) n.º 44/2001, do Conselho, de 22/12/2000, assinalando-se a jurisprudência mais relevante nesse domínio.