Metamodel-based model conformance and multiview consistency checking

Model-driven development, using languages such as UML and BON, often makes use of multiple diagrams (e.g., class and sequence diagrams) when modeling systems. These diagrams, presenting different views of a system of interest, may be inconsistent. A metamodel provides a unifying framework in which to ensure and check consistency, while at the same time providing the means to distinguish between valid and invalid models, that is, conformance. Two formal specifications of the metamodel for an object-oriented modeling language are presented, and it is shown how to use these specifications for model conformance and multiview consistency checking. Comparisons are made in terms of completeness and the level of automation each provide for checking multiview consistency and model conformance. The lessons learned from applying formal techniques to the problems of metamodeling, model conformance, and multiview consistency checking are summarized

Improving Mobile GIS applications through the identification of Geographic Context

Mobile devices are becoming increasingly popular. Their functionalities have become more than just making phone calls, due to regular improvements to these devices. Thus, with their notable increase in computational power, these devices have become able to support applications based on georeferenced data. By allowing the manipulation, visualisation and sharing of such data, these applications (supported by, for example, Google Maps or OpenStreetMap) have also shown an increasingly higher popularity. In this dissertation, we developed an adaptive Geographic Information System for Android devices, which displays relevant information to the user, based on the detected geographic context. The platform is supported by the concept of a context adaptation model, which enables the identification of particular situations in the context of the user, and the consequent adaptation of the application’s interface to the identified event. The context of the user is composed of the information collected by the sensors present in most mobile devices, which also enables the system to automatically adapt its content and thus become more relevant (according to the detected conditions), contributing for a better user experience. The relevant events to be listened to and the actions to be taken accordingly are managed in an administrator online tool, allowing for simplified software maintenance. By defining adaptation rules on aWeb platform, the administrators are able to configure the Android application’s behaviour without having to change the existing code. Finally, the developed platform was tested on a prototype of a Tourism application. The system was evaluated in two distinct parts - Web platform and Android application - by several participants, who agreed that the second is easy to use, while the first requires some previous learning.Os dispositivos móveis são cada vez mais populares. Devido a melhorias constantes destes dispositivos, as suas funcionalidades tornaram-se muito mais do que simplesmente efetuar chamadas. Assim, com a notável evolução do seu poder computacional, estes dispositivos passaram a ser capazes de suportar aplicações baseadas em dados georreferenciados. Ao possibilitar a manipulação, visualização e partilha de tais dados, estas aplicações (suportadas, por exemplo, por Google Maps ou OpenStreetMap) têm também apresentado um crescimento e popularidade cada vez maior. Nesta dissertação, foi desenvolvido um Sistema de Informação Geográfica adaptativo para dispositivos Android, que mostra informações relevantes ao utilizador, com base no contexto geográfico detetado. A plataforma é apoiada por um modelo de adaptação contextual, que permite a identificação de situações particulares no contexto do utilizador, e a consequente adaptação da interface da aplicação ao evento identificado. O contexto do utilizador é composto pelas informações recolhidas pelos sensores presentes na maioria dos dispositivos móveis, que também permite ao sistema adaptar automaticamente o seu conteúdo e, assim, tornar-se mais relevante (de acordo com as condições detectadas), contribuindo para uma melhor experiência de utilizador. Os eventos relevantes a serem tidos em conta e as ações a serem tomadas em conformidade são geridos através de uma ferramenta online de administrador, permitindo uma manutenção de software simples. Ao definir regras de adaptação numa plataforma Web, os administradores podem configurar o comportamento da aplicação Android sem precisar de alterar o código existente. Finalmente, a plataforma desenvolvida foi testada num protótipo de uma aplicação de Turismo. O sistema foi avaliado em duas partes - plataforma Web e aplicação Android - por vários participantes, que concordaram que a segunda é fácil de utilizar, enquanto a primeira requer alguma aprendizagem

Artificial Intelligence for Small Satellites Mission Autonomy

Space mission engineering has always been recognized as a very challenging and innovative branch of engineering: since the beginning of the space race, numerous milestones, key successes and failures, improvements, and connections with other engineering domains have been reached. Despite its relative young age, space engineering discipline has not gone through homogeneous times: alternation of leading nations, shifts in public and private interests, allocations of resources to different domains and goals are all examples of an intrinsic dynamism that characterized this discipline. The dynamism is even more striking in the last two decades, in which several factors contributed to the fervour of this period. Two of the most important ones were certainly the increased presence and push of the commercial and private sector and the overall intent of reducing the size of the spacecraft while maintaining comparable level of performances. A key example of the second driver is the introduction, in 1999, of a new category of space systems called CubeSats. Envisioned and designed to ease the access to space for universities, by standardizing the development of the spacecraft and by ensuring high probabilities of acceptance as piggyback customers in launches, the standard was quickly adopted not only by universities, but also by agencies and private companies. CubeSats turned out to be a disruptive innovation, and the space mission ecosystem was deeply changed by this. New mission concepts and architectures are being developed: CubeSats are now considered as secondary payloads of bigger missions, constellations are being deployed in Low Earth Orbit to perform observation missions to a performance level considered to be only achievable by traditional, fully-sized spacecraft. CubeSats, and more in general the small satellites technology, had to overcome important challenges in the last few years that were constraining and reducing the diffusion and adoption potential of smaller spacecraft for scientific and technology demonstration missions. Among these challenges were: the miniaturization of propulsion technologies, to enable concepts such as Rendezvous and Docking, or interplanetary missions; the improvement of telecommunication state of the art for small satellites, to enable the downlink to Earth of all the data acquired during the mission; and the miniaturization of scientific instruments, to be able to exploit CubeSats in more meaningful, scientific, ways. With the size reduction and with the consolidation of the technology, many aspects of a space mission are reduced in consequence: among these, costs, development and launch times can be cited. An important aspect that has not been demonstrated to scale accordingly is operations: even for small satellite missions, human operators and performant ground control centres are needed. In addition, with the possibility of having constellations or interplanetary distributed missions, a redesign of how operations are management is required, to cope with the innovation in space mission architectures. The present work has been carried out to address the issue of operations for small satellite missions. The thesis presents a research, carried out in several institutions (Politecnico di Torino, MIT, NASA JPL), aimed at improving the autonomy level of space missions, and in particular of small satellites. The key technology exploited in the research is Artificial Intelligence, a computer science branch that has gained extreme interest in research disciplines such as medicine, security, image recognition and language processing, and is currently making its way in space engineering as well. The thesis focuses on three topics, and three related applications have been developed and are here presented: autonomous operations by means of event detection algorithms, intelligent failure detection on small satellite actuator systems, and decision-making support thanks to intelligent tradespace exploration during the preliminary design of space missions. The Artificial Intelligent technologies explored are: Machine Learning, and in particular Neural Networks; Knowledge-based Systems, and in particular Fuzzy Logics; Evolutionary Algorithms, and in particular Genetic Algorithms. The thesis covers the domain (small satellites), the technology (Artificial Intelligence), the focus (mission autonomy) and presents three case studies, that demonstrate the feasibility of employing Artificial Intelligence to enhance how missions are currently operated and designed

Linked Data - the story so far

The term “Linked Data” refers to a set of best practices for publishing and connecting structured data on the Web. These best practices have been adopted by an increasing number of data providers over the last three years, leading to the creation of a global data space containing billions of assertions— the Web of Data. In this article, the authors present the concept and technical principles of Linked Data, and situate these within the broader context of related technological developments. They describe progress to date in publishing Linked Data on the Web, review applications that have been developed to exploit the Web of Data, and map out a research agenda for the Linked Data community as it moves forward