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Publicações

2016

Creativity as a Key Ingredient of Information Systems

Autores
Santos, V; Pereira, J; Martins, J; Goncalves, R; Branco, F;

Publicação
TRENDS AND APPLICATIONS IN SOFTWARE ENGINEERING

Abstract
Resorting to creativity technique and their use to help innovation in the area of information systems had a growing interest. In fact, the global competitiveness and the organizations ability to make effective use of information technology and to focus on innovation and creativity are recognized as being important. So, the perspective of using creativity techniques seems to be promising. In this research work we argue that is possible in all IS areas to take advantages of the use of creative processes. We give a pragmatic reasoning and examples for the introduction of creative processes in all the main IS areas.

2016

Evaluating the influence of skipper skills in the performance of Portuguese artisanal dredge vessels

Autores
Oliveira, MM; Camanho, AS; Walden, JB; Gaspar, MB;

Publicação
ICES JOURNAL OF MARINE SCIENCE

Abstract
It is widely recognized that skippers can have a significant role in their vessel performance levels. However, in many studies that seek to address differences in performance of vessels, the contribution of the skipper is often not quantified, or the influencing factors are not explained. This study examines the effect of social factors, such as family heritage, education and professional expertise, on skipper skill and the economic performance of the Portuguese artisanal dredge fleet. This is done using a stochastic production frontier model and data on the weekly activity of 54 vessels operating during 2013 and 2014. The results suggest that in this fishery age and education levels of skippers are important determinants of efficiency. Experience as a skipper was no determinant of performance, possibly due to the simplicity of the technical equipment onboard. From a managerial perspective, this indicates that local authorities should consider initiatives to enhance the education levels and professional training of skippers, if they aim to improve the effectiveness of artisanal fleets.

2016

BUZZPSS: A Dependable and Adaptive Peer Sampling Service

Autores
Machado, N; Maia, F; Matos, M; Oliveira, R;

Publicação
2016 SEVENTH LATIN-AMERICAN SYMPOSIUM ON DEPENDABLE COMPUTING (LADC)

Abstract
A distributed system is often built on top of an overlay network. Overlay networks enable network topology transparency while, at the same time, can be designed to provide efficient data dissemination, load balancing, and even fault tolerance. They are constructed by defining logical links between nodes creating a node graph. In practice, this is materialized by a Peer Sampling Service (PSS) that provides references to other nodes to communicate with. Depending on the configuration of the PSS, the characteristics of the overlay can be adjusted to cope with application requirements and performance concerns. Unfortunately, overlay efficiency comes at the expense of dependability. To overcome this, one often deploys an application overlay focused on efficiency, along with a safety-net overlay to ensure dependability. However, this approach results in significant resource waste since safety-net overlays are seldom used. In this paper, we focus on safety-net overlay networks and propose an adaptable mechanism to minimize resource usage while maintaining dependability guarantees. In detail, we consider a random overlay network, known to be highly dependable, and propose BUZZPSS, a new Peer Sampling Service that is able to autonomously fine-tune its resource consumption usage according to the observed system stability. When the system is stable and connectivity is not at risk, BUZZPSS autonomously changes its behavior to save resources. Alongside, it is also able to detect system instability and act accordingly to guarantee that the overlay remains operational. Through an experimental evaluation, we show that BUZZPSS is able to autonomously adapt to the system stability levels, consuming up to 6x less resources than a static approach.

2016

VUMO: Towards an Ontology of Urban Mobility Events for Supporting Semi-Automatic Visualization Tools

Autores
Sobral, T; Galvao, T; Borges, J;

Publicação
2016 IEEE 19TH INTERNATIONAL CONFERENCE ON INTELLIGENT TRANSPORTATION SYSTEMS (ITSC)

Abstract
This paper introduces VUMO, a visualization-oriented ontology that formalizes the knowledge about urban mobility events (e.g. ridership and travel intentions) and visualization techniques. It focuses on serving as a foundation for the development of semi-automatic visualization tools, while also facilitating the process of data integration. The ontology allows techniques to be characterized with human perception factors, so they can be considered when automatically infering recommended techniques for a dataset. The ultimate goal is to benefit transportation decision makers and foster the development of semantically rich visualization techniques. We propose a structured visualization workflow based on VUMO, and apply it to the development of a prototype featuring real data extracted from a journey planner mobile application.

2016

Impact of self-production in the operation and regulation of distribution networks

Autores
Coelho, A; Matos, M;

Publicação
IET Conference Publications

Abstract
The emergence of self-consumption in low voltage consumers has technical and regulatory consequences, due to the changes in the network flows. In this paper these impacts are analysed through a small case study where different production/storage arrangements are considered. The technical analysis shows the voltage profiles' variation and identifies possible overvoltages and the effect of mitigation measures like storage. The regulatory analysis shows that, in order to maintain the remuneration of the Distribution System Operator (DSO) and Transmission System Operator (TSO), network tariffs parameters would change dramatically for the ordinary consumers, unless new rules are defined for the contribution of LV consumers.

2016

Layered shape grammars for procedural modelling of buildings

Autores
Jesus, D; Coelho, A; Sousa, AA;

Publicação
VISUAL COMPUTER

Abstract
The effort of creating virtual city environments is reduced using procedural modelling techniques. However, these typically use split-based approaches which can impose limitations on the final geometry, usually enforcing a grid-like structure and require complex geometry to be imported. Layered shape grammars can increase the variability of procedural buildings, while the vectorial definition of shapes introduces the possibility of creating complex shapes that seamlessly blend into the model. We evaluate the contributions with a modelling example and a comparison with split-based procedural modelling techniques. Results show that layers allow more flexibility than split-based techniques in creating variations. Vectorially defined shapes are a step forward in shape grammar expressiveness.

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