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Publicações

2012

Performance assessment of construction companies: A study of factors promoting financial soundness and innovation in the industry

Autores
Horta, IM; Camanho, AS; Moreira da Costa, JM;

Publicação
INTERNATIONAL JOURNAL OF PRODUCTION ECONOMICS

Abstract
The purpose of the paper is to examine trends in the performance of the Portuguese construction industry, and identify the factors that promote excellence and innovation in the sector. From a methodological perspective, this study enhances the construction of composite indicators using the principles of the "benefit of the doubt" weighting. This involves the use of Data Envelopment Analysis to estimate weights for aggregating the key performance indicators of the construction companies. The paper also proposes a new DEA-based method to assess innovation within an industry, identifying the innovative companies and the extent of innovation. The determinants of good performance and innovation are examined using regression techniques and the statistical significance of the results is ensured by the use of bootstrapping. The study reveals that the Portuguese construction industry experienced a remarkable performance improvement during the 1990s, but this growth trend in performance slowed down in recent years. It is concluded that company performance is strongly affected by the national economic context, and that small specialized companies and large contractors tend to achieve the best performance levels.

2012

Intensity Curvature Sensor based on Photonic Crystal Fiber with Three Coupled Cores

Autores
Martins, H; Marques, MB; Jorge, P; Cordeiro, CMB; Frazao, O;

Publicação
MICRO-STRUCTURED AND SPECIALTY OPTICAL FIBRES

Abstract
An intensity curvature sensor using a Photonic Crystal Fiber (PCF) with three coupled cores is proposed. The three cores were aligned and there was an air hole between each two consecutive cores. The fiber had a low air filling fraction, which means that the cores remain coupled in the wavelength region studied. Due to this coupling interference is obtained in the fiber output even if just a single core is illuminated. A configuration using transmission interrogation, which used a section fiber with 0.08 m of PCF as the sensing head, and a configuration using reflection interrogation, which used a section fiber with 0.13 m of PCF as the sensing head, were characterized and compared for curvature sensing. When the fiber is bended along the plane of the cores, one of the lateral cores will be stretched and the other compressed. This changes the coupling between the three cores, changing the optical power intensity. The sensibility of the sensing head was strongly dependent on the direction of bending, having its maximum when the bending direction was along the plane of the cores. A maximum curvature sensitivity of 1.8 dB. m was demonstrated between 0 m and 2.8 m.

2012

Finding the best ranking model for spatial objects

Autores
Tork, HF;

Publicação
CEUR Workshop Proceedings

Abstract
Top-k spatial preference queries has a wide range of applications in service recommendation and decision support systems. In this work we first introduce three state of the art algorithms and apply them on a real data set which includes geographic coordinates and quality data of over 355 hotels, 276 point of interests and 563 restaurants in Lisbon, Portugal extracted from well-known TripAdvisor2. This is the first time that mentioned algorithms are evaluated on a real data set. We also use some optimization tasks for the estimation of algorithms parameters. Finally we rank the hotels using the best obtained ranking model. Result reveals that influence score with a particular radius is able to rank spatial objects very near to the real rankings.

2012

An integrated approach to develop professional and technical skills for informatics engineering students

Autores
Fernandes, JM; van Hattum Janssen, N; Ribeiro, AN; Fonte, V; Santos, LP; Sousa, P;

Publicação
European Journal of Engineering Education

Abstract
Many of the current approaches used in teaching and learning in engineering education are not the most appropriate to prepare students for the challenges they will face in their professional careers. The active involvement of students in their learning process facilitates the development of the technical and professional competencies they need as professionals. This article describes the organisation and impact of a mini-conference and project work - the creation of a software product and its introduction in the market - aimed at the development of professional competencies in general and writing skills in particular. The course was evaluated by assessing the students' perception of the development of a number of professional competencies through a questionnaire completed by 125 students from two consecutive year groups. The results indicate that the project work and the mini-conference had a positive impact on students' perceptions of the development of professional competencies. © 2012 Copyright SEFI.

2012

Phase precession through acceleration of local theta rhythm: a biophysical model for the interaction between place cells and local inhibitory neurons

Autores
Castro, L; Aguiar, P;

Publicação
JOURNAL OF COMPUTATIONAL NEUROSCIENCE

Abstract
Phase precession is one of the most well known examples within the temporal coding hypothesis. Here we present a biophysical spiking model for phase precession in hippocampal CA1 which focuses on the interaction between place cells and local inhibitory interneurons. The model's functional block is composed of a place cell (PC) connected with a local inhibitory cell (IC) which is modulated by the population theta rhythm. Both cells receive excitatory inputs from the entorhinal cortex (EC). These inputs are both theta modulated and space modulated. The dynamics of the two neuron types are described by integrate-and-fire models with conductance synapses, and the EC inputs are described using non-homogeneous Poisson processes. Phase precession in our model is caused by increased drive to specific PC/IC pairs when the animal is in their place field. The excitation increases the IC's firing rate, and this modulates the PC's firing rate such that both cells precess relative to theta. Our model implies that phase coding in place cells may not be independent from rate coding. The absence of restrictive connectivity constraints in this model predicts the generation of phase precession in any network with similar architecture and subject to a clocking rhythm, independently of the involvement in spatial tasks.

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.

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