Abstract
A piston type projector using the PVDF piezoelectric polymer was developed for operating in underwater environment, below 100 kHz. For those frequencies PZT piezoelectric ceramic is usually a preferable choice and PVDF is only considered for frequencies above a few hundreds of kHz. This paper will show that efficient underwater acoustic projectors for frequencies below 100 kHz can be implemented regarding an appropriate impedance adapter is being used. The developed project presents a calibrated transmitting voltage response (TVR) of approximately 166, 160 and 175 dB at 40, 50 and 75 kHz, respectively. The PVDF TVR values are compatible with the PZT projectors available on market with the advantage of having a larger bandwidth than most PZT projectors. To the authors knowledge this is the first time that a PVDF projector attain such characteristics. Although theoretically the PVDF projector bandwidth is larger than 40 to 80 kHz, in practice it was observed that only between those frequencies the project presents a stable operation for the transmission of long-term signals.

Abstract

Abstract
Chairing online Master Programmes requires constant monitoring and decision-making, amidst diversified data and ongoing processes. If misunderstood or misinterpreted, poor decisions may result, as well as lost opportunities to support enrolled students. Decision-making can be supported by dashboards, but there are few prototypes which underwent limited evaluation. We focus on identifying and prototyping efficient visualisation and interaction methods for such a dashboard, to offer online Master Program chairs opportunities for better analysis and decision-making. Design science research was conducted: evaluate and revise an existing prototype; evaluate the revised prototype with master program chairs; design, implementation, and evaluation of a final prototype, again involving master program chairs. The final prototype dashboard provides a way for Master Program chairs to visualize and interact with Master Program data, to support improved analysis of information and quick identification of problems, towards better decision-making.;A coordenação de cursos de mestrado online requer constante acompanhamento e tomada de decisões, com dados diversificados e processos em curso. Se mal interpretados, podem advir decisões inadequadas ou perderem-se oportunidades de apoiar os alunos do curso. Existem painéis de instrumentos de apoio, mas poucos protótipos, carentes de avaliação aprofundada. Focámo-nos na identificação e prototipagem de métodos de visualização e interação para um destes painéis, visando proporcionar aos coordenadores de cursos de mestrado online oportunidades para melhor tomada de decisão. Conduzimos iterações de investigação por ciência da conceção: avaliação e reformulação de protótipo existente; avaliação do protótipo revisto por coordenadores de cursos de mestrado; conceção, implementação e avaliação de protótipo final, novamente envolvendo coordenadores de cursos. O protótipo final constitui uma forma de coordenadores de curso visualizarem e interagirem com os dados do curso, apoiando melhor análise e rápida identificação de problemas, visando melhor tomada de decisões.

Abstract
High penetration of renewable energy sources and energy storage systems has considerably increased the flexibility in power distribution networks operation. However, employing converter-interfaced energy and storage sources may significantly reduce the mechanical inertia and as a result, the power grids may confront serious stability challenges during transient conditions. This article introduces a strategy for enhancing transient stability margin of active distribution networks with high penetration of electric vehicles (EVs). The proposed optimization strategy intends to control EVs contributions during transient stability conditions. The EVs contributions are controlled through a new index proposed based on the system's total corrected critical kinetic energy (TCCKE). The proposed procedure for TCCKE calculation is driven by a hybrid algorithm taking into account the equal area criterion and sensitivity analysis. The suggested procedure for TCCKE only depends on the during fault data and as a result, the proposed optimization strategy is useful to prevent transient instability in the case of first swing instability. The proposed optimization is applied and evaluated on the IEEE test systems. The results clearly demonstrate the applicability and efficacy during a multitude of fault and emergency conditions.

Abstract
The industry tends to increasingly automate as many processes as possible, and to make this possible, they often resort to the use of robotic arms. This paper presents the development of a proposal for a modular joint for robotic arms that allows: to obtain the best possible torque/weight ratio; to be controlled in speed and/or position; to communicate with other joints and external microcontrollers; to keep the cost as low as possible; and to be easily reconfigurable. The proposed prototype was validated with real results.

Abstract
It is commonly assumed by the projects demonstrating concepts for positive energy districts in cities across Europe that citizens want and need to be involved in the development of these concepts as an essential condition for positive energy districts to be deployed successfully and to achieve the expected societal goals. Six different research and innovation projects are investigating the different forms of energy citizenship in positive energy districts and their impacts. They aim to apply a transdisciplinary approach to collaborative research and to impact assessment. The interim results are described, and preliminary conclusions on impact are drawn. The projects each used different approaches to engaging citizens, while differentiating between different groups. Progress is monitored but only fragmentary evidence on the impact has been gathered. Transdisciplinary approaches are being developed but are still immature.