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Publicações

2018

Microgrid protection schemes

Autores
Gomes, M; Coelho, P; Moreira, C;

Publicação
Microgrids Design and Implementation

Abstract
A microgrid embraces a low-voltage (LV) distribution grid with distributed energy resources (DER) and controllable loads. In the last years, there has been a growing awareness in exploiting microgrids to facilitate DER integration in electric power systems as well as to improve reliability and power quality in distribution grids. A microgrid can operate connected to the upstream medium voltage (MV) grid-utility grid-or islanded (disconnected from the MV grid) in a controlled and coordinated way. A major challenge associated with the implementation of microgrids is to design a suitable protection system scheme for different operating conditions. To overcome this challenge, different approaches have been proposed in the literature. The protection systems applied at microgrids must work both in utility grid faults and microgrid faults. Faults on the utility grid could lead to a protection response that isolates the microgrid from the utility grid as fast as required to keep the microgrid safety. On the other hand, faults in the own microgrid require the smallest sector removal of the microgrid to isolate the fault. Due to the presence of several DER in microgrids, the protection systems are also needed to cope with the bidirectional energy flows. Thus, the traditional protection devices (fuses and electromechanical switches) and standard solid-state relays are designed for selectivity purposes, making them inapt to ensure the protection of microgrids. These protection devices do not provide flexibility for setting the tripping characteristics neither the current direction sensitivity feature. Some problems related to protections sensitivity and selectivity arises when a microgrid is in islanded operation (DER generation). Thus, this new paradigm of distribution facilities requires a protection system based on microprocessor relaying and communications. Protecting microgrids in both modes (grid-connected and islanded) can be achieved by using different communication architectures associated with protections. Using centralized or distributed architectures means that the relay protection settings are modified centrally or locally regarding microgrid operating conditions. This chapter aims to provide the key highlights of the available protection schemes used to address microgrid protection issues.

2018

Joint capsule segmentation in ultrasound images of the metacarpophalangeal joint using a split and merge approach

Autores
Martins, N; Sultan, MS; Veiga, D; Ferreira, M; Coimbra, MT;

Publicação
BHI

Abstract
This work presents a new approach for the identification of the joint capsule in ultrasound images of the metacarpophalangeal joint. These images are used to diagnose rheumatic diseases which are one of the main causes of impairment and pain in developed countries. The early diagnosis of these conditions is crucial to a proper treatment and follow-up and so, this work contributes to the automatic extraction of relevant information from the resulting images. The algorithm uses the metacarpus, phalange and extensor tendon positions to create a region of interest. Next, a split and merge approach is used to identify the joint capsule, where the split is done using the Simple Linear Iterative Clustering algorithm and the merge is achieved with a special region growing with shape constraints. After that, the results are refined using a Localizing Active Contours method. Results shown that the segmentation is possible with 60% of the joint capsules identified with a Dice Coefficient higher than 0.7.

2018

Stay true, but innovate!

Autores
Mention, AL; Pinto Ferreira, JJ; Torkkeli, M;

Publicação
Journal of Innovation Management

Abstract
Were you ever asked by a manager to ‘do what you want’, where you felt free to innovate? Did it feel like freedom? Maybe you felt encouraged since you could now experiment your idea, but did it mean that your performance was now on the radar? Could you then stay true to your vision or did you feel the need to compromise so that the ‘numbers lined up’? Either way, you should know that you are not alone. Arguably, we are in an age of paradox1 where simultaneous contradic- tions are all too common. Innovation paradox arises when “the aggressive pursuit of operational excellence and incremental innovation crowds out the possibility of creating ground-breaking innovations” (Davila & Epstein, 2014, p.2). Often these contradictions are meaningful on their own merit but when interdependent on each other, they create tensions in economic, social, environmental and ethical decision-making. In previous editorials, we have shared how digital innovations and societal disparity across the world are influencing strategic decision-making and shifting the innovation mindset. We now stretch the boundaries by suggesting that paradigms relying on economic trade-offs and shared-value that have shaped conventional organisational strategies are no longer sufficient to guide paradoxical tensions in decision-making. (...)

2018

Safe Parallelism: Compiler Analysis Techniques for Ada and OpenMP

Autores
Royuela, S; Martorell, X; Quinones, E; Pinho, LM;

Publicação
RELIABLE SOFTWARE TECHNOLOGIES - ADA-EUROPE 2018

Abstract
There is a growing need to support parallel computation in Ada to cope with the performance requirements of the most advanced functionalities of safety-critical systems. In that regard, the use of parallel programming models is paramount to exploit the benefits of parallelism. Recent works motivate the use of OpenMP for being a de facto standard in high-performance computing for programming shared memory architectures. These works address two important aspects towards the introduction of OpenMP in Ada: the compatibility of the OpenMP syntax with the Ada language, and the interoperability of the OpenMP and the Ada runtimes, demonstrating that OpenMP complements and supports the structured parallelism approach of the tasklet model. This paper addresses a third fundamental aspect: functional safety from a compiler perspective. Particularly, it focuses on race conditions and considers the fine-grain and unstructured capabilities of OpenMP. Hereof, this paper presents a new compiler analysis technique that: (1) identifies potential race conditions in parallel Ada programs based on OpenMP or Ada tasks or both, and (2) provides solutions for the detected races.

2018

Service Design for Value Networks: Enabling Value Cocreation Interactions in Healthcare

Autores
Patricio, L; de Pinho, NF; Teixeira, JG; Fisk, RP;

Publicação
SERVICE SCIENCE

Abstract
In the increasingly complex service environment, value is cocreated through webs of interactions between provider networks and customer networks. This is evident in healthcare services, where well-being can be achieved only through the joint efforts of professional healthcare networks and patient networks. Addressing the challenge of creating network-level services, the service design for value networks (SD4VN) method designs services as enablers of many-to-many value cocreating interactions among network actors. By integrating previous research on value networks and service design, SD4VN develops a process and a set of models beyond supporting dyadic (customer-service provider) interactions to understanding the interrelated activities, interactions, and goals of network actors and designing services to support the different actors in reaching their goals with balanced centricity. Following a design science research approach, this paper presents the SD4VN method and reports on a case application of the method used to design the Portuguese national electronic health record service Plataforma de Dados da Saude (PDS). The case application involved focus groups, indepth interviews, and participatory design sessions with over 170 participants at different service design stages, showing the importance of designing a balanced, integrated service. The case application also shows how SD4VN can support a wider adoption of the service and improve the health service system.

2018

Updating a Robust Optimization Model for Improving Bus Schedules

Autores
Baghoussi, Y; Mendes Moreira, J; Emmerich, MTM;

Publicação
2018 10TH INTERNATIONAL CONFERENCE ON COMMUNICATION SYSTEMS & NETWORKS (COMSNETS)

Abstract
Transportation systems are very complex systems due to the characteristics of their components such as buses. Nowadays, buses are set up to follow a particular schedule that is very sensitive to the changes that occur inside the system. These schedules must frequently be updated, if necessary, due to many reasons. Among these reasons, we have the population growth inside the cities as well as traffic and congestions caused by unforeseen events. To solve the problem of system variability, companies such as the Public Transport Company in the city of Porto (STCP) usually fixes bus schedules with headways adapted to each type of bus lines (i.e., high/low-frequency bus lines). In this work, we adopt a robust optimization model from literature to improve the bus schedules using Automatic Vehicle Location Data collected along the year in the city of Porto. We apply the model to a high-frequency bus line case study. We present the model imperfections and propose new updates.

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