2014
Authors
Bandeira, JM; Fontes, T; Pereira, SR; Fernandes, P; Khattak, A; Coelho, MC;
Publication
17TH MEETING OF THE EURO WORKING GROUP ON TRANSPORTATION, EWGT2014
Abstract
Nowadays, several methods to promote a more sustainable distribution of traffic flows are available. In response to rising energy costs and increased environmental concerns, eco-friendly route choices can be provided individually by means of smart navigation tools that allow several vehicle routing options designed to minimize air pollutant emissions and fuel consumption. Simultaneously, the use of intelligent road pricing systems and the use of variable message signs can change the route choice process of drivers (and thus network equilibrium), by varying the perceived attributes of competing routes. However, so far too little attention has been paid to the fact that the ecofriendliness of various routes may change, depending on vehicle characteristics which may cause problems on the efficiency of these systems. This issue has been empirically addressed in this research, using a database of more than 13,330 km of GPS data in six different Origin-Destination (OD) pairs and 9 different routes. Simultaneously, two different approaches for estimating (CO2, HC, CO, NOx) emissions were tested: a) second-by-second vehicle dynamics, using the Vehicle Specific Power (VSP) instantaneous model; and b) route average speed using the EMEP/PEA methodology. The results show that depending on the characteristics of the routes associated with a certain OD pair, the eco-friendly route may differ according to the vehicle model and the emissions estimation method. Innovative approaches to provide accurate emissions and eco-routing information are needed.
2014
Authors
Moreira, CL; Silva, B;
Publication
2014 IEEE INTERNATIONAL ENERGY CONFERENCE (ENERGYCON 2014)
Abstract
A fully operational Multi-Terminal DC (MTDC) grid will play a strategic role for mainland AC systems interconnection and to integrate offshore wind farms. The importance of such infrastructure requires its compliance with Fault Ride Through (FRT) capability in case of mainland AC faults. In order to provide FRT capability in MTDC grids, communication-free advanced control functionalities exploiting a set of local control rules at the converter stations and wind turbines are identified. The proposed control functionalities are responsible for mitigating the DC voltage rise effect resulting from the reduction of active power injection into onshore AC systems during grid faults. The proposed strategies envision a fast control of the wind turbine active power output as a function of the DC grid voltage rise and constitute alternative options in order to avoid the use of classical solutions based on the installation of chopper resistors in the MTDC grid. The feasibility and robustness of the proposed strategies are demonstrated and discussed in the paper while considering different circumstances.
2014
Authors
Gomes, EF; Jorge, AM; Azevedo, PJ;
Publication
PROCEEDINGS OF THE 18TH INTERNATIONAL DATABASE ENGINEERING AND APPLICATIONS SYMPOSIUM (IDEAS14)
Abstract
In this paper we describe an approach to classifying heart sounds (classes Normal, Murmur and Extra-systole) that is based on the discretization of sound signals using the SAX (Symbolic Aggregate Approximation) representation. The ability of automatically classifying heart sounds or at least support human decision in this task is socially relevant to spread the reach of medical care using simple mobile devices or digital stethoscopes. In our approach, sounds are first pre-processed using signal processing techniques (decimate, low-pass filter, normalize, Shannon envelope). Then the pre-processed symbols are transformed into sequences of discrete SAX symbols. These sequences are subject to a process of motif discovery. Frequent sequences of symbols (motifs) are adopted as features. Each sound is then characterized by the frequent motifs that occur in it and their respective frequency. This is similar to the term frequency (TF) model used in text mining. In this paper we compare the TF model with the application of the TFIDF (Term frequency - Inverse Document Frequency) and the use of bi-grams (frequent size two sequences of motifs). Results show the ability of the motifs based TF approach to separate classes and the relative value of the TFIDF and the bi-grams variants. The separation of the Extra-systole class is overly difficult and much better results are obtained for separating the Murmur class. Empirical validation is conducted using real data collected in noisy environments. We have also assessed the cost-reduction potential of the proposed methods by considering a fixed cost model and using a cost sensitive meta algorithm.
2014
Authors
Martins, R; Monteiro, J; Caldas, P; Santos, JL; Rego, G;
Publication
23RD INTERNATIONAL CONFERENCE ON OPTICAL FIBRE SENSORS
Abstract
In this work, we propose a compact sensor head to perform cryogenic temperature measurements based on a long-period fiber grating. The presented configuration enables the sensor to be interrogated in reflection since a phase-shifted is produced by Fresnel reflection on the end-face of the fiber, cleaved at a quarter-period separation distance from the end of the grating.
2014
Authors
Sioros, G; Miron, M; Davies, M; Gouyon, F; Madison, G;
Publication
FRONTIERS IN PSYCHOLOGY
Abstract
In order to better understand the musical properties which elicit an increased sensation of wanting to move when listening to music groove we investigate the effect of adding syncopation to simple piano melodies, under the hypothesis that syncopation is correlated to groove. Across two experiments we examine listeners' experience of groove to synthesized musical stimuli covering a range of syncopation levels and densities of musical events, according to formal rules implemented by a computer algorithm that shifts musical events from strong to weak metrical positions. Results indicate that moderate levels of syncopation lead to significantly higher groove ratings than melodies without any syncopation or with maximum possible syncopation. A comparison between the various transformations and the way they were rated shows that there is no simple relation between syncopation magnitude and groove.
2014
Authors
Oliveira, N; Barbosa, LS;
Publication
2014 EIGHTH BRAZILIAN SYMPOSIUM ON SOFTWARE COMPONENTS, ARCHITECTURES AND REUSE (SBCARS)
Abstract
Self-adaptive software systems are known to respond at run time to changes detected internally or in their environment, in an attempt to keep meeting their own functional requirements and agreed levels of service. Such response usually targets their architectures and involve, in particular, the possibility of their dynamic reconfiguration. In contexts where change is the rule rather than the exception, it is difficult to predict when exactly such reconfigurations are needed, and if they will lead the system into a suitable configuration. However, knowing the main attributes of the context, it is possible to plan configurations that will be more likely to perform well in some conjugation of values for such attributes. In this paper we discuss both a model that lays down reconfiguration strategies, planned at design time, and a strategy which actively uses such a model to trigger architectural adaptations at run time. This strategy builds on a framework intended to the formal verification of architectural requirements, either from a qualitative or quantitative (probabilistic) perspective.
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