Comunicações confiáveis sem-fios para redes veiculares

Vehicular communications are a promising field of research, with numerous potential services that can enhance traffic experience. Road safety is the most important objective behind the development of wireless vehicular networks, since many of the current accidents and fatalities could be avoided if vehicles had the ability to share information among them, with the road-side infrastructure and other road users. A future with safe, efficient and comfortable road transportation systems is envisaged by the different traffic stakeholders - users, manufacturers, road operators and public authorities. Cooperative Intelligent Transportation Systems (ITS) applications will contribute to achieve this goal, as well as other technological progress, such as automated driving or improved road infrastructure based on advanced sensoring and the Internet of Things (IoT) paradigm. Despite these significant benefits, the design of vehicular communications systems poses difficult challenges, mainly due to the very dynamic environments in which they operate. In order to attain the safety-critical requirements involved in this type of scenarios, careful planning is necessary, so that a trustworthy behaviour of the system can be achieved. Dependability and real-time systems concepts provide essential tools to handle this challenging task of enabling determinism and fault-tolerance in vehicular networks. This thesis aims to address some of these issues by proposing architectures and implementing mechanisms that improve the dependability levels of realtime vehicular communications. The developed strategies always try to preserve the required system’s flexibity, a fundamental property in such unpredictable scenarios, where unexpected events may occur and force the system to quickly adapt to the new circumnstances.The core contribution of this thesis focuses on the design of a fault-tolerant architecture for infrastructure-based vehicular networks. It encompasses a set of mechanisms that allow error detection and fault-tolerant behaviour both in the mobile and static nodes of the network. Road-side infrastructure plays a key role in this context, since it provides the support for coordinating all communications taking place in the wireless medium. Furthermore, it is also responsible for admission control policies and exchanging information with the backbone network. The proposed methods rely on a deterministic medium access control (MAC) protocol that provides real-time guarantees in wireless channel access, ensuring that communications take place before a given deadline. However, the presented solutions are generic and can be easily adapted to other protocols and wireless technologies. Interference mitigation techniques, mechanisms to enforce fail-silent behaviour and redundancy schemes are introduced in this work, so that vehicular communications systems may present higher dependability levels. In addition to this, all of these methods are included in the design of vehicular network components, guaranteeing that the real-time constraints are still fulfilled. In conclusion, wireless vehicular networks hold the potential to drastically improve road safety. However, these systems should present dependable behaviour in order to reliably prevent the occurrence of catastrophic events under all possible traffic scenarios.As comunicações veiculares são uma área de investigação bastante promissora, com inúmeros potenciais serviços que podem melhorar a experiência vivida no tráfego. A segurança rodoviária é o objectivo mais importante por detrás do desenvolvimento das redes veiculares sem-fios, visto que muitos dos atuais acidentes e vítimas mortais poderiam ser evitados caso os veículos tivessem a capacidade de trocar informação entre eles, com a infraestrutura rodoviária e outros utilizadores da estrada. Um futuro com sistemas de transporte rodoviário seguros, eficientes e confortáveis é algo ambicionado pelas diferentes partes envolvidas - utilizadores, fabricantes, operadores da infraestrutura e autoridades públicas. As aplicações de Sistemas Inteligentes de Transporte (ITS) cooperativas vão contribuir para alcançar este propósito, em conjunto com outros avanços tecnológicos, nomeadamente a condução autónoma ou uma melhor infraestrutura rodoviária baseada em sensorização avançada e no paradigma da Internet das Coisas (IoT). Apesar destes benefícios significativos, o desenho de sistemas de comunicações veiculares coloca desafios difíceis, em grande parte devido aos ambientes extremamente dinâmicos em que estes operam. De modo a atingir os requisitos de segurança crítica envolvidos neste tipo de cenários, é necessário um cuidadoso planeamento por forma a que o sistema apresente um comportamento confiável. Conceitos de dependabilidade e de sistemas de tempo-real constituem ferramentas essenciais para lidar com esta desafiante tarefa de dotar as redes veiculares de determinismo e tolerância a faltas. Esta tese pretende endereçar alguns destes problemas através da proposta de arquitecturas e da implementação de mecanismos que melhorem os níveis da dependabilidade das comunicações veiculares de tempo-real. As estratégias desenvolvidas tentam sempre preservar a necessária flexibilidade do sistema, uma propriedade fundamental em cenários tão imprevisíveis, onde eventos inesperados podem ocorrer e forçar o sistema a adaptar-se rapidamente às novas circunstâncias.A contribuição principal desta tese foca-se no desenho de uma arquitectura tolerante a faltas para redes veiculares com suporte da infraestrutura de beira de estrada. Esta arquitectura engloba um conjunto de mecanismos que permite detecção de erros e comportamento tolerante a faltas, tanto nos nós móveis como nos nós estáticos da rede. A infraestrutura de beira de estrada desempenha um papel fundamental neste contexto, pois fornece o suporte que permite coordenar todas as comunicações que ocorrem no meio sem-fios. Para além disso, é também responsável pelos mecanismos de controlo de admissão e pela troca de informação com a rede de transporte. Os métodos propostos baseiam-se num protocolo determinístico de controlo de acesso ao meio (MAC) que fornece garantias de tempo-real no accesso ao canal semfios, assegurando que as comunicações ocorrem antes de um determinado limite temporal. No entanto, as soluções apresentadas são genéricas e podem ser facilmente adaptadas a outros protocolos e tecnologias sem-fios. Neste trabalho são introduzidas técnicas de mitigação de interferência, mecanismos para assegurar comportamento falha-silêncio e esquemas de redundância, de modo a que os sistemas de comunicações veiculares apresentem elevados níveis de dependabilidade. Além disso, todos estes métodos são incorporados no desenho dos componentes da rede veicular, guarantindo que as restrições de tempo-real continuam a ser cumpridas. Em suma, as redes veiculares sem-fios têm o potential para melhorar drasticamente a segurança rodoviária. Contudo, estes sistemas precisam de apresentar um comportamento confiável, de forma a prevenir a ocorrência de eventos catastróficos em todos os cenários de tráfego possíveis.Programa Doutoral em Telecomunicaçõe

Fault-Tolerant, Scalable and Interoperable IoT Platform

Tese de mestrado, Engenharia Informática (Engenharia de Software) Universidade de Lisboa, Faculdade de Ciências, 2020Nowadays the growth of Internet usage is quite visible. Everyday the number of devices connected to the Internet increases, everything may be a smart device capable of interacting with the Internet, from smartphones, smartwatches, refrigerators and much more. All of these devices are called things in the Internet of Things. Many of them are usually constrained devices due to it’s size, usually very small with low capacities such as memory and/or processing power. These kind of devices need to be very efficient in all of their actives. For example, the battery lifetime should be maximized as possible so that the necessity to change each device’s battery could be minimized. There are many technologies that allow communication between devices. Besides the technologies, protocols may be involved in the communication between each device in an IoT system. Communication Protocols define the behaviour that is followed by things when communicating with each other. For example, in some protocols acknowledgments must be used to ensure data arrival, while in others this feature is not enforced. There are many communication Protocols available in the literature. The use of communication protocols and communication models bring many benefits to IoT systems, but they may also benefit from using the cloud. One of the biggest struggles in IoT is the fact that things are very constrained devices in terms of resources (CPU and RAM). With the cloud this would no longer be an issue. Plus, the cloud is able of providing device management, scalability, storage and real time transmission. The characteristics of the communication protocols were studied and an innovative system architecture based on micro-services, Kubernetes and Kafka is proposed in this thesis. This proposal tries to address issues such as scalability, interoperability, fault tolerance, resiliency, availability and simple management of large IoT systems. Supported by Kubernetes, which is an open-source technology that allows micro-services to be extensible, configurable and automatically managed with fault tolerance and Kafka, which is a distributed event log that uses the publish-subscribe pattern, the proposed architecture is able to deal with high number of devices producing and consuming data at the same time. The proposed Fault-Tolerant and Interoperable IoT Architecture is a cluster composed of many components (micro-services) that were implemented using docker containers. The current implementation of the system supports the MQTT, CoAP and REST protocols for data incoming and the same plus websockets for data output. Since the system is based on micro-services, more protocols may be added in a simple way (just a new micro-service must be added). The system is able to convert any protocol into another protocol, e.g., if a message arrives at the system through MQTT protocol, it can be consumed using the CoAP or REST protocol. When messages are sent to the system the payload is stored in Kafka independently of the protocol, and when clients request it, it is consumed from Kafka and encapsulated by the client protocol to be sent to the client. In order to evaluate and demonstrate the capabilities of our proposal a set of experiments were made, which allows to collect information about the performance of the Communication Protocols, the system as a whole, Kubernetes and Kafka. From the experiments we were able to conclude that the message size is not so much important, since the system is able to deal with messages from 39 bytes to 2000 bytes. Since we are designing the system for IoT applications, we considered that messages with 2000 Bytes are big messages. Also, it was recognized that the system is able to recover from crashed nodes and to respond well in terms of average delay and packet loss when low and high throughput are compared. In this situation, there is a significant impact of the RAM usage, but the system still works without problems. In terms of scalability, the evaluation of the system through its cluster under-layer platform (Kubernetes) allowed us to understand that there is no direct relation between the time spent toconstant. However, the same conclusion is not true for the number of instances that are needed at high layer (application layer). Here, time spent to increase the number of instances of a specific application is directly proportional to the number of instances that are already running. In respect to data redundancy and persistence, the experiments showed that the average delay and packet loss of a message sent from a Producer to a Receiver is approximately the same regardless of the number of Kafka instances being used. Additionally, using a high number of partitions has a negative impact on the system’s behaviour

An Activity Theory-based Architecture To Enhance Context-aware Collaboration In Software Development In The Cloud

This research study reviews collaborative software development and assesses the impact of cloud computing in this domain. This is with a view towards identifying challenges to effective context-aware collaboration, as well as opportunities, risks, and potential benefits that could come from a well-defined structured leverage of cloud capabilities. Findings from systematic review of literature indicate that adoption of cloud computing played a significant part in bringing about trends such as: movement of traditional applications and processes to the cloud; cloud development environments; increased distribution in teams and resources; increased diversity in requirements; changes in how software is developed, tested, deployed, accessed, and maintained. These trends have in turn introduced factors such as: massive scale; additional layers of complexity in abstraction levels, entity characteristics and entity relationships within the development process. This additional layer of complexity translates into increase in contexts i.e., information that can be used to characterize states of entities. This is in addition to existing traditional complexity i.e., measure of proportionality of activities and tasks within the process. Some notable efforts towards improving collaboration in software development in the cloud include: transitioning development environments, tools and teams to the cloud; provision of code repositories and version control functionality to support collaboration between developers; provision of platforms to enhance collaboration between developers and end-users in early stages of the process via registered project campaigns and targeted questionnaires; provision of platforms with integrated social networking tools. However, an essential missing piece for more effective context-aware collaboration in the process is, the need for ways of addressing resultant complexity from cloud adoption and capturing actionable contexts. Capturing and communicating contextual information can help improve awareness and understanding and facilitate role-based coordination of distributed team members including users, and not just developers. This would ensure all stakeholders are always on the same page even if not in same location, across all phases of development. The main aim of this research study is to apply a new architecture framework underpinned by the right theoretical foundations, capable of leveraging cloud capabilities, harnessing contexts and addressing complexity to enhance context-aware collaboration in cloud-based software development. To achieve this aim, knowledge gleaned from the systematic literature review and the gap-impact analysis was thematized and synthesized to provide optimal recommendations to serve as roadmap guide for the development and evaluation carried out, and subsequent knowledge contributions. Key dimensions were adapted, along with development of classifications for approaches to enhancing collaboration in software development in the cloud. The key dimensions created were for - assessing collaboration needs; definition of context data and levels; collecting, categorizing, analysing, and applying contextual information to tasks, activities, and stages within software development in the cloud. These dimensions and classifications are useful for identification of reliable ways of measuring collaboration and success factors, as well as managing complexity and ensuring synchronous regularity of process and understanding within the development process in the cloud. A formal process was proposed to aid selection of an appropriate theoretical basis and assembling of a theoretical framework and methodology to underpin the architecture for enhancing context-aware collaboration in cloud-based software development. This was necessary due to the current lack of a de-facto architecture method for cloud-based software development. An activity theory-based architecture has been designed and developed, along with a Proof-of-Concept (POC) implementation that leverages cloud capabilities, for evaluation of the architecture. This architecture presents a novel approach for enhancing collaboration in software development in the cloud due to its underlying activity theory-based tenets that considers ‘activity’ as the unit of analysis, and ideal for activity systems and ease of identification of congruencies and contradictions present or capable impacting related components of the activity system and its ecosystem. The conclusions for this research study, limitations and future research directions have been discussed at the end of this thesis work

Computerized Clinical Decision Support Systems for decision support in patients with breast, lung, colorectal or prostate cancer

Sistemes electrònics; Càncer; Presa de decisionsSistemas electrónicos; Cáncer; Toma de decisionesElectronic systems; Cancer; Decision makingEl objetivo general de este informe de ETS es evaluar la seguridad, eficacia, efectividad y eficiencia de los sistemas electrónicos de apoyo a las decisiones clínicas (computerized Clinical Decision Support Systems o cCDSS), específicamente de los considerados de nivel medio (p. ej. calculadoras pronósticas o GPC automatizadas) y de nivel alto (aquellos que utilizan la IA para formular recomendaciones específicas para un paciente), para el apoyo a la toma de decisiones clínicas relativas al manejo terapéutico, seguimiento o pronóstico de pacientes con cáncer de mama, pulmón, colon-recto o próstata. También se propone evaluar el impacto de los cCDSS en cáncer a nivel organizativo, legal, ético y social/de pacientes.L'objectiu general d'aquest informe d'ETS és avaluar la seguretat, eficàcia, efectivitat i eficiència dels sistemes electrònics de suport a les decisions clíniques (computeritzed Clinical Decision Support Systems o cCDSS), específicament dels considerats de nivell mitjà (p. ex. calculadores pronòstiques o GPC automatitzades) i de nivell alt (aquells que utilitzen la IA per formular recomanacions específiques per a un pacient), per al suport a la presa de decisions clíniques relatives al maneig terapèutic, seguiment o pronòstic de pacients amb càncer de mama, pulmó, còlon-recte o pròstata. També es proposa avaluar l'impacte dels cCDSS en càncer a nivell organitzatiu, legal, ètic i social/de pacients.The overall objective of this HTA report is to evaluate the safety, efficacy, effectiveness, and efficiency of (computeritzed Clinical Decision Support Systems (cCDSS), specifically those considered medium level (e.g. prognostic calculators or automated CPGs) and high level (those that use AI to formulate patient-specific recommendations), for clinical decision support regarding the therapeutic management, follow-up, or prognosis of patients with breast, lung, colon-rectum or prostate cancer. It is also proposed to assess the impact of cCDSS in cancer at organizational, legal, ethical, and social/patient level

Metodología de implantación de modelos de gestión de la información dentro de los sistemas de planificación de recursos empresariales. Aplicación en la pequeña y mediana empresa

La Siguiente Generación de Sistemas de Fabricación (SGSF) trata de dar respuesta a los requerimientos de los nuevos modelos de empresas, en contextos de inteligencia, agilidad y adaptabilidad en un entono global y virtual. La Planificación de Recursos Empresariales (ERP) con soportes de gestión del producto (PDM) y el ciclo de vida del producto (PLM) proporciona soluciones de gestión empresarial sobre la base de un uso coherente de tecnologías de la información para la implantación en sistemas CIM (Computer-Integrated Manufacturing), con un alto grado de adaptabilidad a la estnictura organizativa deseada. En general, esta implementación se lleva desarrollando hace tiempo en grandes empresas, siendo menor (casi nula) su extensión a PYMEs. La presente Tesis Doctoral, define y desarrolla una nueva metodología de implementación pan la generación automática de la información en los procesos de negocio que se verifican en empresas con requerimientos adaptados a las necesidades de la SGSF, dentro de los sistemas de gestión de los recursos empresariales (ERP), atendiendo a la influencia del factor humano. La validez del modelo teórico de la metodología mencionada se ha comprobado al implementarlo en una empresa del tipo PYME, del sector de Ingeniería. Para el establecimiento del Estado del Arte de este tema se ha diseñado y aplicado una metodología específica basada en el ciclo de mejora continua de Shewhart/Deming, aplicando las herramientas de búsqueda y análisis bibliográfico disponibles en la red con acceso a las correspondientes bases de datos

Análise de redes sociais e o sucesso académico: um estudo com ‘grupos’ de alunos no facebook

Os adolescentes são cada vez mais utilizadores assíduos dos sites de redes sociais, disponibilizados na Web 2.0. Assim, desenvolvemos um projeto de investigação sobre o impacto que a colaboração e comunicação online, efetuada através da rede social Facebook, pode ter no rendimento escolar dos alunos na disciplina de Introdução às Tecnologias de Informação e Comunicação (ITIC). Este projeto foi implementado no ano letivo de 2011/2012, a alunos de duas turmas do 9º ano de escolaridade, pertencentes a duas escolas públicas dos concelhos de Oeiras e Cascais. A escolha destas duas escolas prende-se com o facto de, em cada uma destas, ter sido adotado abordagem pedagógicas distintas: uma mais expositiva e outra socioconstrutivista. Os dados recolhidos demonstram que a interação online revela-se positiva e significativamente associada ao rendimento académico dos alunos.info:eu-repo/semantics/publishedVersio