Desafios da internet do futuro

Engenharia Eletrónica e TelecomunicaçõesAs capacidades de conetividade dos equipamentos móveis têm obrigado a constante mudança do modo de operação da rede, exigindo cada vez mais recursos. Visando as futuras redes 5G, existe a necessidade de evoluir as presentes redes móveis, melhorando as suas arquiteturas e mecanismos. Estas futuras redes, vistas como a próxima geração arquitetural das telecomunicações, tenta suportar a "explosão" do número de equipamentos ligados, serviços e tecnologias de acesso, apoiando-se fortemente nas redes definidas por software (do inglês, Software Defined Networks, SDN). Apesar de estas redes definidas por software, estarem a ser exploradas e implementadas no núcleo de rede, atualmente não contemplam o seu impacto em equipamentos sem-fios móveis, de forma a avaliar o possível suporte de controlo. Os desafios associados à extensão dos mechanismos e protocolos, como o OpenFlow, das redes definidas por software até aos equipamentos móveis, não só requerem o desenho de uma infra-estrutura capaz de suportar essa extensão, como também da sua avaliação e provenientes benefícios. Esta dissertação acompanha a tendência destas futuras redes, explorando a interação entre o equipamento móvel e a rede, em ambientes sem-fios heterogéneos, nos quais os mecanismos de SDN são extendidos até equipamentos móveis capazes de não só consumir, como também de produzir informação. Com isto, foi desenvolvida e implementada sobre uma rede sem-fios física uma arquitetura conceptual, na qual os mecanismos SDN são extendidos até ao terminal, suportando diferentes equipamentos móveis com múltiplos fluxos de dados. Os resultados obtidos, mostram a sua viabilidade em cenários de mobilidade sem congestionamento, visando benefícios em extender os mecanismos SDN para controlo de fluxos end-to-end em ambientes sem-fios.The connectivity capabilities of mobile wireless devices have been forever changing how networks operate, increasingly demanding resources from the network. This places a need for novel mobile network architectures and mechanisms, targeting tomorrows challenges, as envisaged by 5G networks research efforts. This future network, seen as the next generation telecommunications architecture, aims to tackle the explosion of connected devices, services and access technologies, relying its architecture on Software Defined Networks (SDN) to compose its underlying mechanisms. Notwithstanding, despite the need for novel control procedures to support and optimize increasingly challenging wireless mobile scenarios, SDN has been being deployed at the core and backhaul sections of the network and is not actively considering its impact directly over the wireless mobile terminals themselves. The challenges associated with the extension of SDN protocols, such as OpenFlow, all the way to the terminal requires the design and evaluation of frameworks that not only provide such mechanisms, but actually evaluate them and their benefits. This thesis shades a light on an important 5G trend, namely the interaction of the mobile node with the network, exploring a framework where SDN mechanisms are extended all the way to the mobile node, in heterogeneous wireless environments featuring different mobile nodes with multiple data flows, which act both as consumers and producers of information. In this way, flow-based mobility management becomes available to a network controller entity, via the OpenFlow protocol. The concept framework was implemented over a physical wireless testbed, validating its contribution in a mobile source-mobility use case, with results highlighting the promising benefits of extending SDN approaches for end-to-end flow control in wireless environments

Micro and macro network slicing: an experimental assessment of the impact of increasing numbers of slices

The fifth generation (5G) telecommunications network aims not only to enhance traffic performance and allow efficient management, but also to enable it to dynamically and flexibly adapt to the traffic demands of different vertical scenarios. In order to support that enablement, the underlying network procedures (i.e., network functions) are being virtualized and deployed in cloud-based environments, allowing for a more optimized usage of the infra-structure resources. In addition, such resources can be sliced, allowing isolated provisioning to specific network functions allocated to disparate vertical deployments. As network slices are envisaged by network operators to fulfill a small number of slices, able to cater towards essential 5G scenario demands (i.e., enhanced mobile broadband, massive machine-type communications and ultra reliable low-latency communications), the total amount of slices existing in a system is currently dictated by the underlying operational overhead placed over the cloud infra-structure. This paper explores the challenges associated to a vision where the network slicing concept is applied with a much greater level of granularity, ultimately allowing it to become a core mechanism of the network’s operation, with large numbers of co-existing slices. In that respect, this paper proposes an architecture framework for instantiation of network slices among network providers, which in turn are able to instantiate sub-slices tailored to use cases and vertical tenants. The evaluation of this concept is done following a two-pronged approach: firstly, different slice dimensions (i.e., from micro to macro) are proposed and discussed, pointing out the benefits and challenges of each proposed slice; secondly, we deployed a mobile network provider (MNO), using OpenAirInterface and FlexRAN frameworks, and experimentally evaluated the its slicing mechanisms. The objective is to provide insight on the challenges and impact associated with the deployment of an increasing amount of slices, using the same available infra-structural resources.publishe

Desenvolvimento de programa para o cálculo de pilares de betão armado

Mestrado em Engenharia CivilA presente dissertação tem por objetivo desenvolver um programa informático que permita dimensionar e verificar a segurança de pilares de betão armado segundo o preconizado no Eurocódigo 2. Para tal, foram implementados os métodos simplificados da Curvatura Nominal e Rigidez Nominal. Procurou-se desenvolver uma aplicação direcionada para o utilizador final, com uma interface simples e organizada, de modo a tornar a utilização intuitiva e expedita. Nesse sentido, adicionaram-se ferramentas que permitem calcular o recobrimento mecânico da armadura, as flexibilidades relativas dos encastramentos parciais nas extremidades do pilar, visualizar graficamente a capacidade resistente ou adicionar novos materiais aos pré-existentes. Pretendeu-se que o programa fosse aplicável tanto a situações académicas como profissionais. Assim, todos os resultados de cálculos intermédios são disponibilizados, o que constitui uma ferramenta de aprendizagem para estudantes. Por outro lado, a capacidade de testar rapidamente e em simultâneo várias combinações de ações, permite a sua utilização por parte de projetistas.This thesis aims to develop a software able to design and check the safety of reinforced concrete columns, according to Eurocode 2. Two simplified methods where implemented: Nominal Curvature Method and Nominal Stiffness Method. The program was developed with focus on the end user, with a simple and organized visual, that enables an intuitive and fast experience. Tools where designed to calculate the minimum concrete cover, the relative flexibilities on end column supports, to generate column capacity charts or add new user defined materials. The program scope includes both academic and professional related problems. Considering that every calculation step is presented, students can use them to learn. On the other hand, the ability to rapidly test several load combinations simultaneously, makes it a powerful tool for designers also

An integration of slicing, NFV, and SDN for mobility management in corporate environments

Online access to information while on the move has conferred businesses with the capability to be constantly accessible and in operation, independently of geographical area or time zone. There are situations, however, that demand technical solutions for specific scenarios, such as controlled access to corporate-based content. Virtual Private Networks (VPNs) allow controlled remote access to con-tent, supporting scenarios such as teleworking. Nonetheless, such mechanisms are not commonly associated with the highly mobile users of today, which can traverse different types of access networks, while still keeping access to con-tent restricted to corporate network usage. In addition, as VPN mechanisms are disassociated from mobility procedures, service disruption can happen or specific mechanisms and clients can be required in end-user's equipment. This paper proposes a framework that leverages Network Slicing, enabled by Software Defined Networking and Network Function Virtualisation, to provide seamless and isolated access to corporate-based content while moving through heterogeneous networks. This solution allows Mobile Network Operators to dynamically instantiate isolated network slices for corporate users, and handover them between 3GPP and non-3GPP networks while users move away from the corporate network. In this way, they are able to keep access to corporate-based content in a transparent way, while maintaining access requirements for the servicebeing used. The framework was implemented and validated over an experimental testbed composed by mobile and Wi-Fi accesses, with results presenting improvements in terms of overhead signaling and data redirection without downtime nor stream reconnection.publishe

Selective laser melting of Ti6Al4V sub-millimetric cellular structures: prediction of dimensional deviations and mechanical performance

Ti6Al4V sub-millimetric cellular structures arise as promising solutions concerning the progress of conventional orthopedic implants due to its ability to address a combination of mechanical, physical and topological properties. Such ability can improve the interaction between implant materials and surrounding bone leading to longterm successful orthopedic implants. Selective Laser Melting (SLM) capability to produce high quality Ti6Al4V porous implants is in great demand towards orthopedic biomaterials. In this study, Ti6Al4V cellular structures were designed, modeled, SLM produced and characterized targeting orthopedic implants. For that purpose, a set of tools is proposed to overcome SLM limited accuracy to produce porous biomaterials with desired dimensions and mechanical properties. Morphological analyses were performed to evaluate the dimensional deviations noticed between the model CAD and the SLM produced structures. Tensile tests were carried out to estimate the elastic modulus of the Ti6Al4V cellular structures. The present work proposes a design methodology showing the linear correlations found for the dimensions, the porosity and the elastic modulus when comparing the model CAD designs with Ti6Al4V structures by SLM.This work was supported by FCT through the grant SFRH/BD/ 128657/2017 and the projects PTDC/EMS-TEC/5422/2014_ADAPT PROSTHESIS, NORTE-01-0145-FEDER-000018 – HAMaBICo and UID/ EEA/04436/2019

Transplante de microbiota fecal no tratamento da infecção por Clostridium difficile recorrente—uma revisão

Clostridium difficile infection (CDI) has become one of the major complications associated with the use of systemic antibiotics. Antimicrobials disrupt the balance of the colonic intestinal flora, predisposing the individual to infections by opportunistic strains, such as an CDI, that can characteristically cause a course of diarrhea and colitis. The standard treatment for these cases is the use of metronidazole or vancomycin for a period of 10 to 14 days. However, it is estimated that this therapy will fail in ∼ 5 to 35% of the patients, who will present a recurrence of CDI. The treatment options for recurrent CDI remain limited, but with promising therapies being constantly researched. The use of stools obtained from a donor to perform fecal microbiota transplantation (FMT) has been gaining space in several health centers, with reported success rates of 80 to 100%. However, there still is a limited experience in this subject, with the need for studies that allow the creation of a specific protocol for FMT

Crescimento e produtividade de alface sob diferentes tipos de cobertura do solo

No Brasil, a alface é a principal hortaliça produzida e comercializada, carecendo, contudo, de tecnologias para otimizar a produção e garantir a sustentabilidade ambiental em áreas agrícolas. Objetivou-se com este trabalho verificar o efeito de diferentes coberturas do solo no crescimento, produtividade de plantas de alface e na temperatura do solo. O delineamento experimental utilizado foi em blocos casualizados, com seis tratamentos e cinco repetições. Os tratamentos estudados consistiram de tipos de cobertura do solo, sendo: cobertura com material vegetal (CVe), polietileno preto (0,020 mm) (PPt), polietileno prata (0,020 mm) (PPr), polietileno branco (0,020 mm) (PBr), polietileno transparente (0,100 mm) (PTr) e solo sem cobertura (Testemunha - T). As variáveis analisadas foram: massa fresca total, número e massa fresca de folhas comerciais, massa fresca de raiz, diâmetro da cabeça e produtividade. Foi realizado o monitoramento da temperatura do solo durante toda condução da cultura. As coberturas com polietilenos prata, branco e preto foram estatisticamente iguais e superiores às demais coberturas para todas as características agronômicas avaliadas na alface. A temperatura do solo foi influenciada pelos tipos de cobertura. Em relação ao solo descoberto, a temperatura do solo aumentou nos tratamentos com coberturas plásticas, e diminuiu no tratamento com cobertura vegetal morta

SISTEMAS DE IMPERMEABILIZAÇÕES (ÊNFASE EM MANTA ASFÁLTICA)

A impermeabilização é uma etapa muito importante para a segurança da edificação e para a integridade física do usuário, pois os agentes trazidos pela água e os poluentes existentes no ar causam danos irreversíveis à estrutura física e diversos prejuízos financeiros difíceis de serem contornados. O processo de impermeabilização vem sendo relegada, na maioria das vezes por contenção de custos e desinformação, resultando no aparecimento de patologias de impermeabilização. Os custos do reparo dessas patologias podem ser até quinze vezes maiores do que se fosse executado no andamento da obra. Sendo assim, esse estudo teve como metodologia inicial a pesquisa bibliográfica que consiste em buscar literatura consolidada acerca do tema escolhido para estudo. Esse estudo apresenta uma análise de múltiplos casos de patologias de impermeabilização, com sugestões de correções e indicações de como prevenir tais patologias. De forma a elucidar melhor sobre o assunto, primeiro foi realizado um levantamento dos principais tipos de materiais usados no processo de impermeabilização, assim como técnicas de uso, aplicação, manuseio, principais cuidados que se deve ter na execução e detalhes construtivos indispensáveis no processo. Palavras chave: Sistemas de impermeabilização. Patologias de impermeabilização. Projeto de impermeabilização