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Publications

2014

Assessment on Baseline and Higher Order Grid Security Criteria: Prospects for Insular Grid Applications

Authors
Bizuayehu, AW; Rodrigues, EMG; Santos, SF; Catalao, JPS; Contreras, J;

Publication
2014 IEEE PES GENERAL MEETING - CONFERENCE & EXPOSITION

Abstract
This paper presents an assessment of baseline and higher order grid security criterion applications on current power grid systems, with a focus on their implications in an island context. It considers the European grid code requirements for N-1 and higher order criteria as essential elements for the future deployment of insular distribution grid systems to improve security and stability. Consequently, in the opening section, major facts about island grid topology and current security challenges are illustrated based on a literature review. Afterwards, different approaches applied for security assessment are discussed. A summary of optimal power flow (OPF) approaches is given based on classic problem formulation, and a distribution grid security constrained assessment algorithm is proposed and assessed for island grid context.

2014

Metaheuristic search based methods for unit commitment

Authors
Rahman, DF; Viana, A; Pedroso, JP;

Publication
INTERNATIONAL JOURNAL OF ELECTRICAL POWER & ENERGY SYSTEMS

Abstract
This paper presents two new solution approaches capable of finding optimal solutions for the thermal unit commitment problem in power generation planning. The approaches explore the concept of "matheuristics", a term usually used to refer to an optimization algorithm that hybridizes (meta)heuristics with mixed integer programming solvers, in order to speed up convergence to optimality for large scale instances. Two algorithms are proposed: "local branching", and an hybridization of particle swarm optimization with a mixed integer programming solver. From extensive computational tests on a broad set of benchmarks, the algorithms were found to be able to solve large instances. Optimal solutions were obtained for several well-known situations with dramatic reductions in CPU time for the larger cases, when compared to previously proposed exact methods.

2014

Cooperation Mechanism for Distributed Resource Scheduling Through Artificial Bee Colony Based Self-Organized Scheduling System

Authors
Madureira, A; Cunha, B; Pereira, I;

Publication
2014 IEEE CONGRESS ON EVOLUTIONARY COMPUTATION (CEC)

Abstract
In this paper a Cooperation Mechanism for Distributed Scheduling based on Bees based Computing is proposed. Where multiple self-interested agents can reach agreement over the exchange of operations on cooperative resources. Agents must collaborate to improve their local solutions and the global schedule. The proposed cooperation mechanism is able to analyze the scheduling plan generated by the Resource Agents and refine it by idle times reducing taking advantage from cooperative and the self-organized behavior of Artificial Bee Colony technique. The computational study allows concluding about statistical evidence that the cooperation mechanism influences significantly the overall system performance.

2014

Development of critical embedded systems using model-driven and product lines techniques: A systematic review

Authors
Queiroz P.G.G.; Braga R.T.V.;

Publication
Proceedings - 2014 8th Brazilian Symposium on Software Components, Architectures and Reuse, SBCARS 2014

Abstract
Several methodologies have been proposed in the last decades to improve the quality of Safety-Critical Embedded Systems (SCES) and, at the same time, keep costs and schedule compatible with project plans. In particular, approaches such as Product Line Engineering (PLE) and Model-Driven Engineering (MDE) offer an interesting solution to reduce development complexity and time to market due to their synergy and common goals. However, the current state of how MDE and PLE can be combined to enhance productivity in the domain of SCES is not clear yet. This paper presents a systematic literature review, with the purpose of obtaining the state of the art of the aproaches, methods and methodologies whose goal is the combination of PLE and MDE for the development of SCES, and to verify the existence of empirical studies that demonstrate the application of these techniques in this type of development. We drew the following conclusions from the review results: (1) The number of studies using PLE with MDE to build SCES is relatively small, but has increased gradually in recent years. (2) The approaches diverge about what is needed to build Model-driven Product Lines. (3) Most of the approaches do not consider to differentiate between hardware and software variabilities. (4) Most of the studies propose the use of UML and feature diagrams. (5) The studies present case studies implemented in different tools and most of them are free. (6) The approaches do not cover the entire development lifecycle.

2014

Collaborative and Privacy-Aware Sensing for Observing Urban Movement Patterns

Authors
Goncalves, N; Jose, R; Baquero, C;

Publication
DATA PRIVACY MANAGEMENT AND AUTONOMOUS SPONTANEOUS SECURITY, DPM 2013

Abstract
The information infrastructure that pervades urban environments represents a major opportunity for collecting information about Human mobility. However, this huge potential has been undermined by the overwhelming privacy risks that are associated with such forms of large scale sensing. In this research, we are concerned with the problem of how to enable a set of autonomous sensing nodes, e.g. a Bluetooth scanner or a Wi-Fi hotspot, to collaborate in the observation of movement patterns of individuals without compromising their privacy. We describe a novel technique that generates Precedence Filters and allows probabilistic estimations of sequences of visits to monitored locations and we demonstrate how this technique can combine plausible deniability by an individual with valuable information about aggregate movement patterns.

2014

Biomass waste co-firing with coal applied to the Sines Thermal Power Plant in Portugal

Authors
Nunes, LJR; Matias, JCO; Catalao, JPS;

Publication
FUEL

Abstract
Environmental issues raised by the use of fossil fuels lead to the search for alternatives that promote the reduction of emissions of greenhouse gases. CO2 has been identified as being the most important and urgent to control. Co-firing is a technique that allows the simultaneous combustion of different types of fuels, for example coal and biomass, combining the advantages of both. This study characterises the advantages of the system and the possibilities of using waste biomass as fuel in a coal-fired thermal power plant. For this, co-firing biomass waste, from forestry operations, with bituminous coal was simulated. Then reductions in CO2 emissions into the atmosphere from Sines Thermal Power Plant in Portugal were calculated, showing a reduction of more than 1,000,000 tons/year of CO2. Also it was verified that although environmentally advantageous, co-firing is still not economically viable due to the high cost of the residual biomass, combined with its low-energy density and high transportation costs.

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