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Publicações

2017

WHAT MAKES A MOBILITY CHAMPION? QUALITATIVE INSIGHTS ON TEACHERS' MOBILITY EXPERIENCES

Autores
Barbosa, B; Santos, CA; Filipe, S; Pinheiro, MM; Simoes, D; Dias, GP;

Publicação
9TH INTERNATIONAL CONFERENCE ON EDUCATION AND NEW LEARNING TECHNOLOGIES (EDULEARN17)

Abstract
Teachers’ mobility is one of the facets of Higher Education Institutions internationalization, and despite its importance in implementing the program's purposes it is still disregarded by researchers, with most mobility studies focusing on students. This research concentrates on highly active mobility teachers and aims to delve into their experiences, namely by identifying facilitators and goals for this repeated internationalization and by analyzing the outcomes of these initiatives in their personal lives, professional activity, home and host students, and for their Universities as a whole. This study adopts a qualitative exploratory approach. Having as sample universe the teachers of one Portuguese University that in a 7-year period (2009-2016) engaged in mobility experiences under the Erasmus program (N = 107), 8 were identified as having the highest number of initiatives and were invited to participate in this study. From these mobility champions, 5 accepted, resulting in 5 phenomenological interviews. Data was collected in January 2017. The participants shared an integrated view of the Erasmus mobility, being essential for its success the additional opportunities of joint research and the strengthening of international relationships and networks. Prior relations with teachers from the host University and ongoing research projects stood out among the facilitators. The opportunity to observe and get to know other cultural settings was also mentioned as one determinant stimulus. Still, the outcomes in terms of teaching methodologies and best practices as well an effective impact in home students seemed residual. Moreover, the ability to encourage other teachers to join the program was very limited, often confined to close colleagues and research partners. Despite its exploratory nature, this study demonstrates the relevance of further research on mobility champions to assess the success and possible pitfalls of repeated mobility experiences in terms of extended institutional outcomes and well as individual gratification of the teachers involved. Based on the results, we suggest the consideration of a wider set of outcomes in the appraisal of mobility initiatives, as well as the widespread of champions’ insights on the topic in order to motivate inexperienced teachers to embrace internationalization. Hopefully this paper is able to inspire not only research but also teaching mobility initiatives.

2017

From software extensions to product lines of dataflow programs

Autores
Goncalves, RC; Batory, D; Sobral, JL; Riche, TL;

Publicação
SOFTWARE AND SYSTEMS MODELING

Abstract
Dataflow programs are widely used. Each program is a directed graph where nodes are computations and edges indicate the flow of data. In prior work, we reverse-engineered legacy dataflow programs by deriving their optimized implementations from a simple specification graph using graph transformations called refinements and optimizations. In MDE speak, our derivations were PIM-to-PSM mappings. In this paper, we show how extensions complement refinements, optimizations, and PIM-to-PSM derivations to make the process of reverse engineering complex legacy dataflow programs tractable. We explain how optional functionality in transformations can be encoded, thereby enabling us to encode product lines of transformations as well as product lines of dataflow programs. We describe the implementation of extensions in the ReFlO tool and present two non-trivial case studies as evidence of our work's generality.

2017

A control strategy for a multi-terminal HVDC network integrating wind farms to the AC grid

Autores
Khenar, M; Adabi, J; Pouresmaeil, E; Gholamian, A; Catalao, JPS;

Publicação
INTERNATIONAL JOURNAL OF ELECTRICAL POWER & ENERGY SYSTEMS

Abstract
This paper describes a novel control strategy of voltage source converters (VSC) in large-scale wind farm applications, in order to achieve a constant DC voltage for connecting to the long transmission system based on multi-terminal high voltage direct current (HVDC) technology. The control strategy is based on a multi-loop current and voltage control for tracking the predetermined value of the DC link voltage in the rectifier side station to achieve proper performance in the irregular circumstances of wind farm operation. In addition, the control strategy is able to transmit the maximum input power to the consumption side in different situations in grid side converter. Grid connection of the HVDC system is analysed under two conditions: balanced AC grid, and connection of unbalanced nonlinear load into the AC grid. The control strategy guarantees injection of minimum harmonic current components from the grid to the loads. MATLAB simulation results are presented to demonstrate the effectiveness of the proposed strategy for different types of variations in AC voltage amplitude and frequency of wind turbines output voltage.

2017

Foreword to the Special Section on Reconfigurable Computing

Autores
Derrien, S; Atasu, K; Cardoso, JMP; Becker, J;

Publicação
JOURNAL OF SIGNAL PROCESSING SYSTEMS FOR SIGNAL IMAGE AND VIDEO TECHNOLOGY

Abstract

2017

Balancing a Mixed-Model Assembly System in the Footwear Industry

Autores
Sadeghi, P; Rebelo, RD; Soeiro Ferreira, J;

Publicação
IFIP Advances in Information and Communication Technology

Abstract
Portuguese footwear industry has improved dramatically to become one of the main world players. This work is part of a project in cooperation with a large footwear company, operating a new automated assembly equipment, integrating various lines. Balancing such lines implies going from an almost manual preparation executed by experienced operators, to a planning supported by optimisation systems. These complex mixed-model lines have distinctive characteristics, which make balancing a unique problem. The paper proposes the ASBsm – Assembly System Balancing Solution Method, a new method that integrates a constructive heuristic and an improvement heuristic, which takes inspiration from Tabu Search. The solutions obtained, based on real instances, are quite encouraging when compared with other effected factory solutions. Consequently, the balances obtained by ASBsm are now being implemented and articulated with sequencing methods. © IFIP International Federation for Information Processing 2017.

2017

Assessment of Ancillary Service Demand Response and Time of Use in a Market-Based Power System Through a Stochastic Security Constrained Unit Commitment

Autores
Talari, S; Shafie khah, M; Hajibandeh, N; Catalao, JPS;

Publicação
TECHNOLOGICAL INNOVATION FOR SMART SYSTEMS

Abstract
In this paper, the impacts of an incentive-based Demand Response, i.e., Ancillary Service DR (ASDR), and a price-based DR, i.e., Time of Use (ToU), are revealed in a restructured power system which has some wind farms. This network is designed based on the pre-emptive market which is a day-ahead market with a balancing market prognosis. It is a proper mechanism to deal with the stochastic nature of non-dispatchable and outage of all units of the network. With Monte Carlo Simulation (MCS) method, several scenarios are generated in order to tackle the variability and uncertainties of the wind farms generation. The impacts of merging ASDR and ToU are investigated through running a two-stage stochastic security constrained unit commitment (SCUC), separately

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