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Publicações

2015

Normality and Nondegeneracy for Optimal Control Problems with State Constraints

Autores
Fontes, FACC; Frankowska, H;

Publicação
JOURNAL OF OPTIMIZATION THEORY AND APPLICATIONS

Abstract
In this paper, we investigate normal and nondegenerate forms of the maximum principle for optimal control problems with state constraints. We propose new constraint qualifications guaranteeing nondegeneracy and normality that have to be checked on smaller sets of points of an optimal trajectory than those in known sufficient conditions. In fact, the constraint qualifications proposed impose the existence of an inward pointing velocity just on the instants of time for which the optimal trajectory has an outward pointing velocity.

2015

Towards an engine for coordination-based architectural reconfigurations

Autores
Rodrigues, F; Oliveira, N; Barbosa, LS;

Publicação
COMPUTER SCIENCE AND INFORMATION SYSTEMS

Abstract
Software reconfigurability became increasingly relevant to the architectural process due to the crescent dependency of modern societies on reliable and adaptable systems. Such systems are supposed to adapt themselves to surrounding environmental changes with minimal service disruption, if any. This paper introduces an engine that statically applies reconfigurations to (formal) models of software architectures. Reconfigurations are specified using a domain specific language-ReCooPLa-which targets the manipulation of software coordination structures, typically used in service-oriented architectures (soa). The engine is responsible for the compilation of ReCooPLa instances and their application to the relevant coordination structures. The resulting configurations are amenable to formal analysis of qualitative and quantitative (probabilistic) properties.

2015

Scheduling and Batching in Multi-Site Flexible Flow Shop Environments

Autores
Santos, AS; Madureira, AM; Varela, MLR; Putnik, GD; Kays, HME; Karim, ANM;

Publicação
2015 10TH IBERIAN CONFERENCE ON INFORMATION SYSTEMS AND TECHNOLOGIES (CISTI)

Abstract
Global competition and the customers demand for customized products with shorter due dates, marked the introduction of the Extended Enterprise. In this Extended Manufacturing Environment (EME), lean, virtual, networked and distributed enterprises collaborate to respond to the market demands. In this paper we study the influence of the batch size on Flexible Flow Shop makespan minimization problem FFC vertical bar vertical bar C-max for two multi-sites approaches, the FSBF (Flow Shop Based Factories) and the PMBF (Parallel-Machines Based Factories). The computational study demonstrates how the performance of the PMBF model decreases with the increase of batch size and determines the batch sizes in which the performance is similar.

2015

Measuring the simultaneous quantity game in OMEL spot electricity market

Autores
Moutinho, V; Moreira, AC; Mota, JH;

Publicação
International Journal of Energy Economics and Policy

Abstract
In the electricity spot market the various competitive levels, as well as their subsequent changes in the market equilibrium, are justified by the simultaneous quantity game between electricity generators. It is expected that the dominant market players employ differentiated strategic behaviours, thus, permitting the quantification of such differentiated effects on the use of market power. The various competitive levels, as well as their subsequent changes in the market equilibrium, are justified by the simultaneous quantity game. The results show that the quantities purchased in the spot market for sale in open market influence prices, i.e., when there is an imbalance in the estimated long-term relationship, prices themselves move in order to recover the state of equilibrium, which reveals that, in the long-term, the OMEL Price is weakly exogenous to the cointegration vector, whereas quantities purchased for sale in open market move towards the reestablishment of the long-term equilibrium.

2015

Holistic Analysis for Fork-Join Distributed Tasks supported by the FTT-SE Protocol

Autores
Garibay Martinez, R; Nelissen, G; Ferreira, LL; Pedreiras, P; Pinho, LM;

Publicação
2015 IEEE WORLD CONFERENCE ON FACTORY COMMUNICATION SYSTEMS (WFCS)

Abstract
This paper presents a holistic timing analysis for fixed-priority fork-join Parallel/Distributed tasks (P/D tasks) over a Flexible Time Triggered - Switched Ethernet (FTT-SE) network. The holistic approach considers both time-triggered and event-triggered tasks/messages.

2015

An integer programming approach for Balancing and Scheduling in Extended Manufacturing Environment

Autores
Kays, HME; Karim, ANM; Varela, MLR; Santos, AS; Madureira, AM;

Publicação
2015 10TH IBERIAN CONFERENCE ON INFORMATION SYSTEMS AND TECHNOLOGIES (CISTI)

Abstract
In the fiercely competitive era induced by expansion of open business archetypes, the managerial aspects of Extended Manufacturing Environments (EMEs) are experiencing growing concerns. There is no scope of leaving a possible operational improvement unexplored. For enhanced operational efficiency and capacity utilization the balancing and scheduling problems of EMEs are, therefore, rightfully considered and an integer programme is proposed in this paper. The model is designed in a spread sheet and solved through What'sBest optimizer. The model capabilities is assessed through a test problem. The results have demonstrated that the model is capable of defining optimized production schedules for EMEs.

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