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Publicações

Publicações por HumanISE

2012

Specifying UML Protocol State Machines in Alloy

Autores
Garis, AG; Paiva, ACR; Cunha, A; Riesco, D;

Publicação
Integrated Formal Methods - 9th International Conference, IFM 2012, Pisa, Italy, June 18-21, 2012. Proceedings

Abstract
A UML Protocol State Machine (PSM) is a behavioral diagram for the specification of the external behavior of a class, interface or component. PSMs have been used in the software development process for different purposes, such as requirements analysis and testing. However, like other UML diagrams, they are often difficult to validate and verify, specially when combined with other artifacts, such as Object Constraint Language (OCL) specifications. This drawback can be overcome by application of an off-the-shelf formal method, namely one supporting automatic validation and verification. Among those, we have the increasingly popular Alloy, based on a simple relational flavor of first-order logic. This paper presents a model transformation from PSMs, optionally complemented with OCL specifications, to Alloy. Not only it enables automatic verification and validation of PSMs, but also a smooth integration of Alloy in current software development practices. © 2012 Springer-Verlag.

2012

Building and Exploring Semantic Equivalences Resources

Autores
Carvalho, G; de Matos, DM; Rocio, V;

Publicação
LREC 2012 - EIGHTH INTERNATIONAL CONFERENCE ON LANGUAGE RESOURCES AND EVALUATION

Abstract
Language resources that include semantic equivalences at word level are common, and its usefulness is well established in text processing applications, as in the case of search. Named entities also play an important role for text based applications, but are not usually covered by the previously mentioned resources. The present work describes the WES base, Wikipedia Entity Synonym base, a freely available resource based on the Wikipedia. The WES base was built for the Portuguese Language, with the same format of another freely available thesaurus for the same language, the TeP base, which allows integration of equivalences both at word level and entity level. The resource has been built in a language independent way, so that it can be extended to different languages. The WES base was used in a Question Answering system, enhancing significantly its performance.

2012

Searching a Mixed Corpus in the Light of the New Portuguese Orthographic Norm

Autores
Carvalho, G; Falé, I; de Matos, DM; Rocio, V;

Publicação
Computational Processing of the Portuguese Language - 10th International Conference, PROPOR 2012, Coimbra, Portugal, April 17-20, 2012. Proceedings

Abstract
A mixed corpus of Portuguese is one in which texts of different origins produce different spelling variants for the same word. A new norm, which will bring together the written texts produced both in Portugal and Brazil, giving then a more uniform orthography, has been effective since 2009, but what happens in the perspective of search, to corpora created before the norm came into practice, or within the transition period? Is the information they contain outdated and worthless? Do they need to be converted to the new norm? In the present work we analyse these questions. © 2012 Springer-Verlag.

2012

Spatial patterns of linear and nonparametric long-term trends in Baltic sea-level variability

Autores
Donner, RV; Ehrcke, R; Barbosa, SM; Wagner, J; Donges, JF; Kurths, J;

Publicação
NONLINEAR PROCESSES IN GEOPHYSICS

Abstract
The study of long-term trends in tide gauge data is important for understanding the present and future risk of changes in sea-level variability for coastal zones, particularly with respect to the ongoing debate on climate change impacts. Traditionally, most corresponding analyses have exclusively focused on trends in mean sea-level. However, such studies are not able to provide sufficient information about changes in the full probability distribution (especially in the more extreme quantiles). As an alternative, in this paper we apply quantile regression (QR) for studying changes in arbitrary quantiles of sea-level variability. For this purpose, we chose two different QR approaches and discuss the advantages and disadvantages of different settings. In particular, traditional linear QR poses very restrictive assumptions that are often not met in reality. For monthly data from 47 tide gauges from along the Baltic Sea coast, the spatial patterns of quantile trends obtained in linear and nonparametric (spline-based) frameworks display marked differences, which need to be understood in order to fully assess the impact of future changes in sea-level variability on coastal areas. In general, QR demonstrates that the general variability of Baltic sea-level has increased over the last decades. Linear quantile trends estimated for sliding windows in time reveal a wide-spread acceleration of trends in the median, but only localised changes in the rates of changes in the lower and upper quantiles.

2012

Quantile Analysis of Relative Sea-Level at the Hornbaek and Gedser Tide Gauges

Autores
Barbosa, SM; Madsen, KS;

Publicação
GEODESY FOR PLANET EARTH: PROCEEDINGS OF THE 2009 IAG SYMPOSIUM

Abstract
The quantification of the long-term variability of relative sea-level is a fundamental problem in geodesy. In the present study, quantile regression is applied for characterising the long-term variability in relative sea-level at the Gedser and Hornbaek tide gauges, in the North Sea-Baltic Sea transition zone. Quantile regression allows to quantify not only the rate of change in mean sea-level but also in extreme heights, providing a more complete description of long-term variability. At Gedser the lowest relative heights are increasing at a rate approximately 40% higher than the mean rate, while at Hornbaek the relative sea-level slopes are stable across most of the quantiles. A 30-year running window analysis shows that the linear trends display considerable decadal variability over the twentieth century for both stations.

2012

Contemporary sea level in the Chagos Archipelago, central Indian Ocean

Autores
Dunne, RP; Barbosa, SM; Woodworth, PL;

Publicação
GLOBAL AND PLANETARY CHANGE

Abstract
Long term mean sea level in the Chagos Archipelago has been relatively stable over the similar to 20 year length of the available instrumental records. Tide-gauge data from Diego Garcia (1988-2000, and 2003-2011) show no statistically significant long-term rise, whilst the rates of rise obtained from the satellite altimeter record for 1993-2011 span the range of 0.16-4.56 mm yr(-1) in the surrounding sea areas (70-74 degrees E and 4-9 degrees S) and are also consistent with a zero rate except in the far south of the region. The dominant feature is one of considerable inter-annual variability in mean sea level of up to similar to 10 cm, such that the very weak seasonal pattern of highest and lowest sea level in February and May respectively, is absent or reversed in some years. The Indian Ocean Dipole appears to exert an important influence on mean sea level in the area, with positive and negative dipole mode indices preceding periods of elevated or lowered sea levels respectively. The Chagos also lie outside the Indian Ocean cyclone belt and experience relatively low wind speeds, and there is no evidence of changes in the wind or wave environment in the past 20 years. Although in an area of seismic activity, there is no record of island subsidence, indeed on Diego Garcia minor crustal uplift of 0.63 +/- 0.28 SE mm yr(-1) has occurred between 1996 and 2009. Collectively, these results suggest that this has been a relatively stable physical environment, and that these low-lying coral islands should continue to be able to support human habitation, as they have done for much of the last 200 years. Nonetheless, future sea-level rise and its effect on the Chagos remains an important issue for further studies such as those of the Intergovernmental Panel on Climate Change.

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