Abstract
This paper addresses the stability analysis of a real island power system following the transformation occurring in the generation portfolio: from a 100 % synchronous-generation-based system (associated to a fleet of diesel generators) to a hybrid power system dominated by power electronics converters. The integration of a battery-wind-photovoltaic power plant in the island creates the necessary conditions for operating the system without synchronous units scenarios with a system dominated by power electronics - or, at least to minimize its use - scenarios with a reduced number of synchronous units in operation. The possibility of operating the system under these conditions is assured by grid-forming inverters connected to battery energy storage systems, that are responsible for performing frequency and voltage control tasks either in parallel with synchronous units or when synchronous units are disconnected. The resulting transient stability issues for the aforementioned operational scenarios are discussed and evaluated through dynamic simulations.

Abstract
It is undeniable that the world is taking a turn for the digital. Banking, shopping, working, education, entertainment, everything has its own digital equivalent or means thereof. This includes language learning. Nowadays, there is a myriad of (mobile and digital) possibilities to study, learn and improve a person’s knowledge of virtually any language. Thus, there should be potential benefits in their use in academic level (foreign) language learning, but also in an individual “self-learning" process. In this study, we choose to tackle mobile apps and their impact in the teaching/learning of languages, the perception of their usefulness and their impact (positive or otherwise) on the subject. To achieve this, a literature review on the subject was conducted, in addition to twenty interviews performed with students of the University of Aveiro. Supported by our literature review, we can safely state that language learning is just one of the many segments of both life and academia that can only be positively affected by digitalisation, and that we will continue seeing a rising trend towards that goal. © Springer Nature Switzerland AG 2019.

Abstract
The decarbonization of the electrical system (ES) is an inevitable truth. Thus, many economies that share concerns about climate change, invest in renewable sources to help contain the global warming. However, the massive integration of these renewable sources, which brings more intermittency and volatility, together with the natural variation of consumption, pose greater challenges that should be mitigated with adequate tools, as offered by a liberalized and organized electrical market. To help cost reduction in a market environment, the coordination between different Transmission System Operators (TSOs) is of utmost importance. The objective of this work is to provide a framework analysis for the sharing of ancillary services (AS) in the context of the Iberian ES, in particular a techno-economic analysis for the secondary reserve (SR) control. The SR control is fundamental to correct load variations and help stabilize the ES where the TSOs are inserted. To this end, the main goal is to control the regional imbalance of the Iberian Peninsula, in a coordinated way, with a minimization of costs. The results show that it is possible to generate synergies in 45% of the market periods and an average profit of 3.4 M(sic) per year. There are enough reasons to implement the coordination procedures between the Iberian TSOs in order to manage their own SRs in a profitable and reliable way, and to become more competitive when exchanging with other European TSOs.

Abstract
This study presents and applies noninvasive subject specific validation of human whole-body (WB) center of mass (COM) kinematic from 3D anthropometric multibody model using dynamic data from ground reaction forces during impulse phase at standard maximum vertical jump (MVJ) with long countermovement (CM) on countermovement jump (CMJ) and short CM on drop jump (DJ) for comparison with MVJ without CM on squat jump (SJ), assessing lower limb CM contribution and muscle stretch-shortening cycle (SSC) at WB COM vertical impulse. A small group of n = 6 sports and physical education degree students with (21.5 ± 1.4) years old, without previous injuries, specific sport abilities or train were weighed (76.7 ± 9.3) kg and their height measured (1.79 ± 0.06) m. Adhesive reflective marks were attached at main upper and lower limb joints. Each subject performed a total of 3 trial at each MVJ, CMJ, DJ and SJ. During trial tests kinematics of anatomical points were registered with two JVC GR-VL9800 digital video cameras at 100 Hz and ground reaction forces with AMTI platform model BP2416-4000 CE operating at 1000 Hz. WB COM kinematics was determined using calibrated SIMI motion tracking of joint reflective marks and Dempster model selecting vertical WB COM displacement ?zk according to higher amplitude and research interest on MVJ WB COM movement for CM and SSC assessment. Dynamic of WB COM vertical displacement ?zd was determined from double time integration of COM vertical acceleration. Comparison of kinematic ?zk and dynamic ?zd was statistically tested on average and variance at each MVJ type, ?zk with ?zd and on root mean square-error (RMSE) during impulse phase. Results present similar variability of ?zk and ?zd at each MVJ p > 0.05, with mean values discriminating CMJ different means p < 0.05 from DJ and SJ with equal means p > 0.05, pointing dynamic data as suitable for validation of WB COM movement from 3D anthropometric image as well as for detection of different RMSE at each type of MVJ, its influence on assessment of CM and SSC and improve accuracy on kinematic, dynamic measurements and models. © Springer Nature Switzerland AG 2019.

Abstract
This study has the objective of select the best service at image processing and recognition, running in the cloud, and best suited for usage in systems to aid and improve the daily lives of blind people. To accomplish this purpose, a set of candidate services was built, including Microsoft Cognitive Services and Google Cloud Vision. A test mobile app was developed to automatically take pictures, which are sent to the online cloud services for processing. The results and the functionalities were evaluated with the aim to measure their accuracy and relevance. The following variables were registered: relative accuracy, represented by the ratio of the number of accurate results vs. the number of results shown; confidence degree, representing the service accuracy (when provided by the service); and relevance, identifying situations that can be useful in the daily lives of the blind people. The results have shown that these two services, Microsoft Cognitive Services and Google Cloud Vision, provided good accuracy and significance, in supporting systems to help blind people in their daily tasks. It was chosen some functionalities in two APIs of services running in the cloud like face identification, image description, objects, and text recognition. © BEIESP.

Abstract