Abstract
Power systems rely on ancillary services (ASs) to ensure system security and stability. Until recently, only the conventional power generation resources connected to the transmission grids were allowed to provide these ASs managed by the transmission system operators (TSOs), while distribution system operators (DSOs) had a more passive role, focused on guaranteeing distribution capacity to bring power to final consumers with enough quality. Now, with the decarbonization, digitalization and decentralization processes of the electrical networks, the growing integration of distributed energy resources (DERs) in distribution grids are displacing conventional generation and increasing the complexity of distribution networks' operation, requiring the implementation of new active and coordinated management strategies between TSOs and DSOs. In this context, DERs are becoming potential new sources of flexibility for both TSOs and DSOs in helping to manage the power system. This paper proposes a systematic characterization of both traditional and potentially new ASs for TSOs, and newly expected DSO local system services to support the new distribution grid operation paradigm, reviewing, in addition, the main TSO-DSO coordination mechanisms.

Abstract
In recent years we have seen a large adherence to social media by various Higher Education Institutions (HEI) with the intent of reaching their target audiences and strengthen their brand recognition. It is important for organizations to discover the true audience-aggregating themes resulting from their communication strategies, as it provides institutions with the ability to monitor their organizational positioning and identify opportunities and threats. In this work we create an automatic system capable of identifying HEI Twitter communication strategies. We gathered and analyzed more than 18k Twitter publications from 12 of the top-HEI according to the 2019 Center for World University Rankings (CWUR). Results show that there are different strategies, and most of HEI had to adapt them to the covid situation. The analysis also shows the prediction of topics and retweets for a HEI cannot just be based on recent historical data.

Abstract
This paper presents a strategy based on mixedinteger linear programing (MILP) model to improve the resilience in electric distribution systems (EDSs). The restoration process considers operational resources such as the optimal coordination of dynamic switching operations, islanding operation of distributed generation (DG) units, and displacement of mobile emergency generation (MEG) units. In addition, the benefits of considering a demand response (DR) program to improve the recoverability of the system are also studied. The switching operations aim to separate the in-service from the out-of-service part of the system keeping the radiality of the grid. The proposed MILP model is formulated as a stochastic scenario-based problem where the uncertainties are associated with PV-based power generation and demand consumption. The objective function minimizes the amount of energy load shedding after fault, and the generation curtailment of the PV-based DG. To validate the proposed strategy, a 33-bus EDS is analyzed under different test cases. Results show the benefits of coordinating the dynamic switching operations, the optimal scheduling of MEG units, and a demand response program during the restoration process.

Abstract
Data acquisition by electromyography, as well as the muscle stimulation, has become more accessible with the new developments in the wearable technology and medicine. In fact, for treatments, games or sports, it is possible to find examples of the use of muscle signals to analyse specific aspects related, e.g., to disease, injuries or movement impulses. However, these systems are usually expensive, does not integrate data acquisition with the muscle stimulation and does not exhibit an adaptive control behaviour that consider the pathology and the patient response. This paper presents a wearable system that integrates the signal acquisition and the electrostimulation using dry thin-film titanium-based electrodes. The acquired data is transmitted to a mobile application running on a smartphone by using Bluetooth Low Energy (BLE) technology, where it is analysed by employing artificial intelligence algorithms to provide customised treatments for each patient profile and type of pathology, and taking into consideration the feedback of the acquired electromyography signal. The acquired patient's data is also stored in a secure cloud database to support the physician to analyse and follow-up the clinical results from the rehabilitation process.

Abstract
In this article, a new MIMO smartphone antenna array with compact resonators is introduced for the fifth-generation mobile terminals. The proposed design was developed on an FR4 substrate with relative permittivity epsilon(r)=4.3 and dielectric loss tangent delta=0.025. The antenna contains eight modified monopole antenna components. The elements are fed by improved L-shaped microstrip feeding lines and cover dual-band frequency rang including 3.30-3.65 GHz and 5.25-5.85 GHz of sub 6 GHz 5G. At 3.47 GHz the Ants. 1, 4, 5, 8 have maximum reflection coefficients of -25 dB while Ants. 2, 3, 6, 7 have reflection coefficients of -20 dB at 5.5 GHz. Essential features of the designed smartphone antenna including S-parameters, radiation patterns, gains, and efficiencies are inspected and sufficient results are observed. The design is highly compact and can be integrated into smartphone circuits.

Abstract
Technological advances and the use of mobile solutions to make smartphone users’ daily life easier is a mindset that has revolutionized the society lifestyle in the past years. In the public transport sector, mobile ticketing is an example of the applicability of mobile solutions in a real context. Using one smartphone to purchase and validate tickets is a revolutionary idea that has acquired fans around the world. The convenience of use and time savings throughout the process are positive aspects, however, the success of the adoption of such services is limited. Based on the case of Porto, Portugal and particularly of the mobile app And, this study intends to understand customer churn factors of mobile ticketing services by analysing data from customer complaints and from usage history. Thus, an analysis of the complaints, the complainers and the effects of complaints is presented. A strategy for capturing and retaining users is also proposed considering four stages of mobile ticketing apps lifecycle: user onboarding, user engagement, user retention and user reinstall. © 2021, ICST Institute for Computer Sciences, Social Informatics and Telecommunications Engineering.