Co-created corporate social responsability initiatives on social media

The subject addressed in this thesis is the emerging online co-created Corporate Social Responsibility (CSR). As the traditional approaches on CSR communication are revealing to be unable of raising awareness and increasing stakeholder engagement, often failing to improve positive relationships with consumers, the present research focused on a new methodology for implementing such activities: a more participatory process, where organizations and stakeholders extend co-creation from consumption products to social responsibility initiatives. There is still little research in the CSR literature about the opportunities offered by participatory activities and how they affect awareness and engagement in social media environments. Thus, the main purpose of the current research was to examine if organizations that engage stakeholders in social media with co-creative approaches, allowing them to be active participants and decision-makers in their online CSR activities, can be more effective in building awareness, increasing stakeholders’ empowerment and participation levels, than firms who use the conventional design and communication of these activities, where the stakeholder has no participation in the process and is merely taken as a passive agent.O assunto abordado nesta tese é a emergente co-criação online de iniciativas de Responsabilidade Social das Empresas (RSE). Sendo que as abordagens tradicionais de comunicação de RSE se têm revelado incapazes de aumentar a "awareness" e o "engagement" dos "stakeholders", muitas vezes não conseguindo melhorar as relações com os consumidores, o presente estudo focou-se numa nova metodologia para implementar estas atividades: um processo mais participativo, onde as organizações e os "stakeholders" estendem a co-criação de produtos de consumo às iniciativas de responsabilidade social. Existe ainda escassa pesquisa na literatura de RSE sobre as oportunidades oferecidas pelas atividades participativas e como elas afetam a "awareness" e o "engagement" nas redes sociais. Assim, o principal objetivo neste estudo foi examinar se as organizações que envolvem os seus "stakeholders" nas redes sociais com abordagens co-criativas, permitindo que eles sejam participantes ativos e decisores nas atividades "online" de RSE, poderão ser mais eficazes na construção de "awareness", aumentando o "empowerment" e os níveis de participação dos seus "stakeholders", do que as empresas que utilizam o design e a comunicação tradicionais dessas atividades, onde os "stakeholders" não participam no processo e são simplesmente considerados agentes passivos

Ergodicity of polygonal slap maps

Polygonal slap maps are piecewise affine expanding maps of the interval obtained by projecting the sides of a polygon along their normals onto the perimeter of the polygon. These maps arise in the study of polygonal billiards with non-specular reflections laws. We study the absolutely continuous invariant probabilities of the slap maps for several polygons, including regular polygons and triangles. We also present a general method for constructing polygons with slap maps having more than one ergodic absolutely continuous invariant probability.Comment: 17 pages, 6 figure

Hyperbolic polygonal billiards with finitely many ergodic SRB measures

We study polygonal billiards with reflection laws contracting the reflected angle towards the normal. It is shown that if a polygon does not have parallel sides facing each other, then the corresponding billiard map has finitely many ergodic SRB measures whose basins cover a set of full Lebesgue measure.Comment: 26 pages, 2 figure

A short review on welding and joining of high entropy alloys

Fundacao para a Ciencia e a Tecnologia (FCT -MCTES) via the project UIDB/00667/2020 (UNIDEMI).High entropy alloys are one of the most exciting developments conceived in the materials science field in the last years. These novel advanced engineering alloys exhibit a unique set of properties, which include, among others, good mechanical performance under severe conditions in a wide temperature range and high microstructural stability over long time periods. Owing to the remarkable properties of these alloys, they can become expedite solutions for multiple structural and functional applications. Nevertheless, like any other key engineering alloy, their capacity to be welded, and thus become a permanent feature of a component or structure, is a fundamental issue that needs to be addressed to further expand these alloys’ potential applications. In fact, welding of high entropy alloys has attracted some interest recently. Therefore, it is important to compile the available knowledge on the current state of the art on this topic in order to establish a starting point for the further development of these alloys. In this article, an effort is made to acquire a comprehensive knowledge on the overall progress on welding of different high entropy alloy systems through a systematic review of both fusion-based and solid-state welding techniques. From the current literature review, it can be perceived that welding of high entropy alloys is currently gaining more interest. Several high entropy alloy systems have already been successfully welded. However, most research works focus on the well-known CoCrFeMnNi. For this specific system, both fusion and solid-state welding have been used, with no significant degradation of the joints’ mechanical properties. Among the different welding techniques already employed, laser welding is predominant, potentially due to the small size of its heat source. Overall, welding of high entropy alloys is still in its infancy, though good perspectives are foreseen for the use of welded joints based on these materials in structural applications.publishersversionpublishe

Novel culture systems to model testicular function and organization

In vitro systems to model the testicular microenvironment are required to study physiology and pathology of the testis, the gonadotoxic effect of environmental and pharmaceutical chemicals, as well as to explore the mechanisms ruling spermatogonial stem cell (SSC) self-renewal and differentiation. The knowledge produced in in vitro experiments, using animal, but most importantly utilizing human models, will contribute to the discovery of safe medical treatments and might provide translational tools to treat male infertility problems. The current models are vital to study the testicular microenvironment in vitro, but further improvements are required to more closely reconstruct the testicular organization and function found in vivo. The main focus of the research conducted in this thesis was to establish and optimize three-dimensional culture conditions to further improve the current approaches to model testicular architecture and physiology in vitro. For that purpose, we explore three distinct approaches: the three-layer gradient system (3-LGS) to culture rat testicular cells suspended in extracellular matrix (ECM) components; the decellularized testicular extracellular matrix (DTM) to culture human testicular cells in their native ECM; and the organ culture system in the air-liquid interface to culture human testicular cells in their native tissue organization. During our experiments, we found that the 3-LGS promoted the reorganization of rat testicular cells into seminiferous tubule-like organoids with both a functional blood-testis barrier and the capacity to maintain proliferative undifferentiated germ cells. Moreover, the DTM allowed the generation of human testicular organoids that, despite not demonstrating characteristic testicular organization, were able to produce testosterone and inhibin B as well as to maintain spermatogonia proliferating during the entire culture period. Finally, the organ culture system served to maintain human testicular tissue in viable conditions and to demonstrate differences in terms of testicular somatic cell functionality among different patient groups exposed to chemotherapy or treatments against haematological diseases. In perspective, the rat and human organoid systems demonstrate potential to explore aspects of testicular development and toxicology, but also the possibility to, easier than before, manipulate the culture conditions to study the influence of different niche elements on SSC self-renewal and differentiation. Moreover, the organ culture system showed the aptitude to be used as a quality control tool in the assessment of bio-banked human testicular tissue and to help in determining the best-fit fertility preservation strategy for each group of patients

Exploração de algoritmos de consenso no Quorum

As blockchain technology matures, more industries are becoming interested in evaluating if the technology can answer their needs for decentralized systems that guarantee data immutability and traceability. Quorum is a blockchain platform that accommodates enterprise use-cases by extending Ethereum to support private transactions and a higher transaction throughput. To achieve this, Quorum replaced Ethereum’s proof-of-stake consensus mechanism with proof-of-authority ones, supporting four different algorithms: Raft, Clique, IBFT 1.0, and QBFT. This work explores Quorum’s consensus algorithms and how they affect performance and fault-tolerance, in order to assess the best use cases for each and what should drive their choice. A GoQuorum network was set up, and benchmarks were run against this system under different scenarios while only changing the consensus algorithm for each scenario. Results showed that Raft is the most performant consensus algorithm in Quorum in both private and public transactions. Additionally, QBFT achieved the same performance as IBFT, and Clique was the worst performer across the board, particularly due to having high resource-usage. Regarding fault-tolerance, it was found that bringing validator nodes down at random, when the network has high-availability, had no impact on networks under any of the consensus algorithms.Com blockchain a entrar numa fase de maturidade, cada vez mais indústrias procuram avaliar se esta tecnologia responde às suas necessidades de sistemas distribuídos que garantam a imutabilidade e rastreabilidade dos seus dados. Quorum é uma plataforma blockchain que procura acomodar os casos de uso destas empresas ao extender Ethereum para suportar transações privadas e um maior número de transações por segundo. Para esse efeito, o Quorum substituiu o mecanismo de consenso proof-ofstake do Ethereum por um mecanismo de proof-of-authority, onde quatro algoritmos são suportados: Raft, Clique, IBFT 1.0, e QBFT. Este trabalho explora os algoritmos de consenso suportados pelo Quorum de modo a determinar como estes afetam o desempenho e tolerância a falhas das redes, e consequentemente perceber os melhores casos de uso para estes algoritmos e que fatores ter em conta aquando a sua escolha. Foi criada uma rede de GoQuorum, e vários testes de desempenho foram corridos contra a rede sob diferentes cenários, onde para cada cenário a única variável foi o algoritmo de consenso. Os resultados mostraram que o Raft foi o algoritmo de consenso com melhor desempenho, tanto em transações públicas como privadas. Adicionalmente, o QBFT e o IBFT atingiram o mesmo desempenho, e o Clique o pior de todos, particularmente pelo seu alto uso de recursos do sistema. Quanto a tolerância a falhas, foi concluído que trazer nós validadores abaixo aleatoriamente enquanto o sistema está configurado com alta disponibilidade não tem impacto nas redes, independentemente do algoritmo de consenso utilizado

Towards a human-in-the-loop control for a smart orthotic system

Dissertação de mestrado integrado em Engenharia Biomédica (área de especialização em Eletrónica Médica)Stroke is the main cause of paralysis. This pathology has provoked a considerable increase of persons with motor impairments. With a therapy focused on each clinical case, the total or partial recovery can be achieved. Powered orthoses have been developed to promote an effective recover, based on repetitive gait training and user’s active participation. Many control approaches have been developed to control these devices, but none of them promotes an user-oriented strategy focused to the user’s needs. In an attempt of solving this issue, a new approach named Human-in-the-loop is emerging. This strategy allows the adaptation of some assistive parameters based on the user’s energetic cost, promoting a therapy tailored to each end-user needs. However, to estimate the energy expenditure, the use of non-ergonomic sensors, not suitable for clinical context, is required. Thus, it is necessary to find new ways of estimating energy expenditure using wearable and comfortable sensors. In this dissertation, the first steps to introduce the Human-in-the-loop strategy into a powered orthosis are presented. For this purpose, two strategies were developed: a strategy that allows the angular trajectory adaptation in real-time and other that promotes a stiffness adaptation all over the gait cycle. Both strategies were validated with healthy subjects. In the first strategy, the orthosis was able to modify its assistance in a fraction of microseconds, and the end-users were able to follow her with a median error below 10%. Regarding the second strategy, the results show that the orthosis allowed an effective change in the systems’ interaction stiffness, promoting an active participation of each user during its assistance. The energetic impact of using the robotic assistive device is also presented. As it promotes an energy expenditure augmentation in more than 30% in comparison to walk without the device, the necessity of implementing the Human-in-the-loop strategy was highlighted. In an attempt of finding an ergonomic technique to estimate the energetic cost, the use of machine learning algorithms was tested. The results, obtained with a MLP and a LSTM, prove that it is possible to estimate the energy expenditure with a mean error close to 11%. Future work consists in the implementation of the model in real-time and the collection of more data with the aforementioned control approaches, in a way of constructing a more robust model.O AVC é uma das maiores causas de paralisia. Esta patologia, cada vez mais com maior incidência nos jovens, tem provocado um aumento considerável de pessoas com problemas de mobilidade. Com uma terapia focada a cada caso clínico, a recuperação total ou parcial pode ser conseguida. As ortóteses ativas têm vindo a ser desenvolvidas com o propósito de promover uma recuperação eficaz, baseada em treinos repetitivos e numa participação ativa dos utilizadores. Várias abordagens de controlo têm vindo a ser desenvolvidas para controlar estes dispositivos, mas nenhuma delas promove uma estratégia orientada às necessidades do utilizador. Na tentativa de solucionar este problema, uma nova abordagem, designada por Human-in-the-loop está a emergir. Baseada no custo energético, esta estratégia permite adaptar parâmetros da assistência, promovendo uma terapia focada e direcionada a cada utilizador. No entanto, para estimar o custo energético, recorre-se ao uso de sensores que não são adequados para contexto clínico. Assim, torna-se necessário estudar novas formas de estimar o custo energético. Nesta dissertação são apresentados os primeiros passos para introduzir o controlo Human-in-the-loop numa ortótese ativa. Para isso, duas estratégias foram apresentadas: uma estratégia que permite adaptar a trajetória angular da ortótese, em tempo real, e outra que promove a adaptação da complacência do sistema ao longo do ciclo da marcha. Ambas foram validadas com sujeitos saudáveis. Relativamente à primeira abordagem, a ortótese foi capaz de modificar a sua assistência em microssegundos, e os utilizadores foram capazes de a seguir com um erro mediano inferior a 10%. No que diz respeito à segunda abordagem, os resultados mostram que a ortótese promoveu uma alteração eficaz da complacência de interação, promovendo uma participação ativa do utilizador durante a sua assistência. O impacto energético do uso do sistema robótico é, também, apresentado. Promovendo um aumento do custo energético em mais de 30%, a necessidade da estratégia Human-in-the-loop foi realçada. Na tentativa de encontrar uma técnica para estimar o custo energético, recorreu-se ao uso de machine learning. Os resultados, obtidos com uma MLP e uma LSTM, provam que é possível estimar o custo energético com um erro médio próximo dos 11%. Trabalho futuro passa pela implementação do modelo em tempo real e a recolha de mais dados com as abordagens de controlo apresentadas, de forma a construir um modelo mais robusto

A Customizable IoT Platform Developed Using Low-Code

In nowadays’ societies and businesses’ ecosystems of acceleration, it is of most importance the digitalization of the formers. In this sense, Internet of Things (IoT) emerges to connect devices to the internet, allowing the access to large amounts of data and, through its analysis, to act upon it. An IoT platform allows, among others, to manage IoT devices. Nonetheless, its development is still a complex and expensive process that requires high technical knowledge. To accelerate developments when building IoT applications, this thesis proposes the use of Low-Code platforms, such as Outsystems. To improve the user experience, an embedded customizable dashboard is included in the platform. To achieve this, a reusable Forge component was built and is currently available for download and in use by the community. This component allows to provide drag and drop functionalities to both web and mobile applications. In this case, it will allow the reordering of dashboard cards to personalize dashboards. Another component that enables barcode/qr code reading by Zebra devices is also included in this thesis. To assess the developed IoT platform, an IoT device prototype was created, using an Arduino with an ESP module, as well as a set of sensors and actuators that communicate with the IoT platform via the Message Queuing Telemetry Transport (MQTT) protocol.No ecossistema de aceleração em que a sociedade e as indústrias se encontram actualmente, é da maior importância a rápida digitalização das mesmas. O conceito de Internet of Things (IoT) surge então para conectar uma grande diversidade de dispositivos à internet, possibilitando o acesso a uma grande quantidade de dados e, aquando da análise dos mesmos, optimizar um conjunto de operações. Plataformas IoT são ferramentas bastante úteis em projectos IoT. Estas permitem, entre outros, a gestão de dispositivos IoT, no entanto, o seu desenvolvimento é um processo complexo e demorado que requer elevados orçamentos e conhecimentos técnicos. Para acelerar o desenvolvimento deste tipo de plataformas, esta dissertação propõe o uso plataformas de desenvolvimento Low-Code, nomeadamente Outsystems. Para melhorar a experiência de utilizador, neste trabalho é proposta uma plataforma IoT com dashboards personalizáveis, utilizando uma arquitetura modular. Para tal, foi desenvolvido um componente reutilizável, publicado na Forge e que está atualmente disponível e a ser utilizado pela comunidade. O mesmo permite adicionar a funcionalidade de drag and drop em aplicações web e mobile. Neste caso, o componente permite arrastar cartões, de forma a personalizar dashboards. Um outro componente que permite a leitura de códigos qr/de barras foi também desenvolvido e encontra-se disponível para download. Para validar a plataforma desenvolvida, foi criado um protótipo de um dispositivo IoT, utilizando um Arduino com um módulo ESP e um conjunto de sensores e atuadores, que comunica com a plataforma através do protocolo MQTT