QoS of IP services in a fieldbus network: on the limitations and possible improvements

This paper focuses on the problem of providing efficient scheduling mechanisms for IP packets encapsulated in the frames of a real-time fieldbus network - the PROFIBUS. The approach described consists on a dual-stack approach encompassing both the controlrelated traffic ("native" fieldbus traffic) and the IPrelated traffic. The overall goal is to maintain the hard real-time guarantees of the control-related traffic, while at the same time providing the desired quality of service (QoS) to the coexistent IP applications. We start to describe the work which have been up to now carried out in the framework of the European project RFieldbus (High Performance Wireless Fieldbus in Industrial Multimedia-Related Environments - IST-1999-11316). Then we identify its limitations and point out solutions that are now being addressed out of the framework of the above-mentioned European project.

From task scheduling in single processor environments to message scheduling in a PROFIBUS fieldbus network

In this paper we survey the most relevant results for the prioritybased schedulability analysis of real-time tasks, both for the fixed and dynamic priority assignment schemes. We give emphasis to the worst-case response time analysis in non-preemptive contexts, which is fundamental for the communication schedulability analysis. We define an architecture to support priority-based scheduling of messages at the application process level of a specific fieldbus communication network, the PROFIBUS. The proposed architecture improves the worst-case messages’ response time, overcoming the limitation of the first-come-first-served (FCFS) PROFIBUS queue implementations.

Timing analysis of an inter-cell mobility procedure for a wired/wireless PROFIBUS network

Recently, there have been a few research efforts towards extending the capabilities of fieldbus networks to encompass wireless support. In previous works we have proposed a hybrid wired/wireless PROFIBUS network solution where the interconnection between the heterogeneous communication media was accomplished through bridge-like interconnecting devices. The resulting networking architecture embraced a Multiple Logical Ring (MLR) approach, thus with multiple independent tokens, where the communication between different domains was supported by the Inter-Domain Protocol (IDP). The proposed architecture also supports mobility of stations between different wireless cells. To that hybrid wired/wireless networking architecture we have proposed a worst-case response timing analysis of the IDP, without considering inter-cell mobility (or handoff) of stations. In this paper, we advance that previous work by proposing a worst-case timing analysis of the mobility procedure.

Timing analysis of a multiple logical ring wired/wireless PROFIBUS network

Recently, there have been a few research efforts towards extending the capabilities of fieldbus networks to encompass wireless support. In previous works we have proposed a hybrid wired/wireless PROFIBUS network solution where the interconnection between the heterogeneous communication media was accomplished through bridge-like interconnecting devices. The resulting networking architecture embraced a multiple logical ring (MLR) approach, thus with multiple independent tokens, to which a specific bridging protocol extension, the inter-domain protocol (IDP), was proposed. The IDP offers compatibility with standard PROFIBUS, and includes mechanisms to support inter-cell mobility of wireless nodes. We advance that work by proposing a worst-case response timing analysis of the IDP.

Towards network-on-chip agreement protocols

Demands for functionality enhancements, cost reductions and power savings clearly suggest the introduction of multiand many-core platforms in real-time embedded systems. However, when compared to uni-core platforms, the manycores experience additional problems, namely the lack of scalable coherence mechanisms and the necessity to perform migrations. These problems have to be addressed before such systems can be considered for integration into the realtime embedded domain. We have devised several agreement protocols which solve some of the aforementioned issues. The protocols allow the applications to plan and organise their future executions both temporally and spatially (i.e. when and where the next job will be executed). Decisions can be driven by several factors, e.g. load balancing, energy savings and thermal issues. All presented protocols are analytically described, with the particular emphasis on their respective real-time behaviours and worst-case performance. The underlying assumptions are based on the multi-kernel model and the message-passing paradigm, which constitutes the communication between the interacting instances.

Engineering a search and rescue application with a wireless sensor network - based localization mechanism

The advent of Wireless Sensor Network (WSN) technologies is paving the way for a panoply of new ubiquitous computing applications, some of them with critical requirements. In the ART-WiSe framework, we are designing a two-tiered communication architecture for supporting real-time and reliable communications in WSNs. Within this context, we have been developing a test-bed application, for testing, validating and demonstrating our theoretical findings - a search&rescue/pursuit-evasion application. Basically, a WSN deployment is used to detect, localize and track a target robot and a station controls a rescuer/pursuer robot until it gets close enough to the target robot. This paper describes how this application was engineered, particularly focusing on the implementation of the localization mechanism.

Repeater-based hybrid wired/wireless PROFIBUS network simulator

This technical report describes the Repeater-Based Hybrid Wired/Wireless PROFIBUS Network Simulator that implements a simulation model of the repeater-based approach. This approach defines the mechanism to extend the PROFIBUS protocol to supprot wireless communication, in which the interconnection of the wired and wireless segments is done by a intermediate system operating at Physical Layer, as repeater.

Modeling of the lung impedance using a fractional order ladder network with constant phase elements

The self similar branching arrangement of the airways makes the respiratory system an ideal candidate for the application of fractional calculus theory. The fractal geometry is typically characterized by a recurrent structure. This study investigates the identification of a model for the respiratory tree by means of its electrical equivalent based on intrinsic morphology. Measurements were obtained from seven volunteers, in terms of their respiratory impedance by means of its complex representation for frequencies below 5 Hz. A parametric modeling is then applied to the complex valued data points. Since at low-frequency range the inertance is negligible, each airway branch is modeled by using gamma cell resistance and capacitance, the latter having a fractional-order constant phase element (CPE), which is identified from measurements. In addition, the complex impedance is also approximated by means of a model consisting of a lumped series resistance and a lumped fractional-order capacitance. The results reveal that both models characterize the data well, whereas the averaged CPE values are supraunitary and subunitary for the ladder network and the lumped model, respectively.

Remote experimentation network - yielding an inter-university peer-to-peer e-service

The goal of this paper is to discuss the benefits and challenges of yielding an inter-continental network of remote laboratories supported and used by both European and Latin American Institutions of Higher Education. Since remote experimentation, understood as the ability to carry out real-world experiments through a simple Web browser, is already a proven solution for the educational community as a supplement to on-site practical lab work (and in some cases, namely for distance learning courses, a replacement to that work), the purpose is not to discuss its technical, pedagogical, or economical strengths, but rather to raise and try to answer some questions about the underlying benefits and challenges of establishing a peer-to-peer network of remote labs. Ultimately, we regard such a network as a constructive mechanism to help students gain the working and social skills often valued by multinational/global companies, while also providing awareness of local cultural aspects.

Two-production-period in a duopoly with nonprofit and for-profit firms

We investigate endogenous roles in a competition between a nonprofit firm and a for-profit firm in a homogeneous goods market, by allowing two production periods. We find that the Cournot-type equilibrium and one Stackelberg-type equilibrium where the nonprofit firm becomes the follower exist; however, another tackelberg-type equilibrium where the nonprofit firm becomes the leader does not exist.

Sistema de Torre de Refrigeração

Mestrado em Engenharia Química - Ramo Optimização Energética na Indústria Química

Determinação do teor de compostos aromáticos policíclicos de óleos minerais isolantes para transformadores

Mestrado em Engenharia Química - Ramo Optimização Energética na Indústria Química

Anotação colaborativa de conteúdos utilizando jogos com propósito

Com o crescimento da informação disponível na Web, arquivos pessoais e profissionais, protagonizado tanto pelo aumento da capacidade de armazenamento de dados, como pelo aumento exponencial da capacidade de processamento dos computadores, e do fácil acesso a essa mesma informação, um enorme fluxo de produção e distribuição de conteúdos audiovisuais foi gerado. No entanto, e apesar de existirem mecanismos para a indexação desses conteúdos com o objectivo de permitir a pesquisa e acesso aos mesmos, estes apresentam normalmente uma grande complexidade algorítmica ou exigem a contratação de pessoal altamente qualificado, para a verificação e categorização dos conteúdos. Nesta dissertação pretende-se estudar soluções de anotação colaborativa de conteúdos e desenvolver uma ferramenta que facilite a anotação de um arquivo de conteúdos audiovisuais. A abordagem implementada é baseada no conceito dos “Jogos com Propósito” (GWAP – Game With a Purpose) e permite que os utilizadores criem tags (metadatos na forma de palavras-chave) de forma a atribuir um significado a um objecto a ser categorizado. Assim, e como primeiro objectivo, foi desenvolvido um jogo com o propósito não só de entretenimento, mas também que permita a criação de anotações audiovisuais perante os vídeos que são apresentados ao jogador e, que desta forma, se melhore a indexação e categorização dos mesmos. A aplicação desenvolvida permite ainda a visualização dos conteúdos e metadatos categorizados, e com o objectivo de criação de mais um elemento informativo, permite a inserção de um like num determinado instante de tempo do vídeo. A grande vantagem da aplicação desenvolvida reside no facto de adicionar anotações a pontos específicos do vídeo, mais concretamente aos seus instantes de tempo. Trata-se de uma funcionalidade nova, não disponível em outras aplicações de anotação colaborativa de conteúdos audiovisuais. Com isto, o acesso aos conteúdos será bastante mais eficaz pois será possível aceder, por pesquisa, a pontos específicos no interior de um vídeo.

Modelling a network of heterogeneous e-learning systems

In recent years emerged several initiatives promoted by educational organizations to adapt Service Oriented Architectures (SOA) to e-learning. These initiatives commonly named eLearning Frameworks share a common goal: to create flexible learning environments by integrating heterogeneous systems already available in many educational institutions. However, these frameworks were designed for integration of systems participating in business like processes rather than on complex pedagogical processes as those related to automatic evaluation. Consequently, their knowledge bases lack some fundamental components that are needed to model pedagogical processes. The objective of the research described in this paper is to study the applicability of eLearning frameworks for modelling a network of heterogeneous eLearning systems, using the automatic evaluation of programming exercises as a case study. The paper surveys the existing eLearning frameworks to justify the selection of the e-Framework. This framework is described in detail and identified the necessary components missing from its knowledge base, more precisely, a service genre, expression and usage model for an evaluation service. The extensibility of the framework is tested with the definition of this service. A concrete model for evaluation of programming exercises is presented as a validation of the proposed approach.

Recycling of pultrusion production waste into innovative concrete-polymer composite solutions

In this study, the added value resultant from the incorporation of pultrusion production waste into polymer based concretes was assessed. For this purpose, different types of thermoset composite scrap material, proceeding from GFRP pultrusion manufacturing process, were mechanical shredded and milled into a fibrous-powdered material. Resultant GFRP recyclates, with two different size gradings, were added to polyester based mortars as fine aggregate and filler replacements, at various load contents between 4% up to 12% in weight of total mass. Flexural and compressive loading capacities were evaluated and found better than those of unmodified polymer mortars. Obtained results highlight the high potential of recycled GFRP pultrusion waste materials as efficient and sustainable admixtures for concrete and mortar-polymer composites, constituting an emergent waste management solution.