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Publications

2014

Tracking of an underwater visual target with an autonomous surface vehicle

Authors
Figueiredo, AB; Ferreira, BM; Matos, AC;

Publication
2014 OCEANS - ST. JOHN'S

Abstract
This paper presents the development of a first approach to a vision-based target detection. The ultimate objective of this work is to position an autonomous surface vehicle relative to a target. Experiments in a controlled indoor environment were conducted to test the developed system. The experimental results are analyzed and show that the tracking performances achieve errors in the order of a few centimetres.

2014

Editorial

Authors
Pinho L.;

Publication
Ada User Journal

Abstract

2014

Bacterial community variations in an alfalfa- rice rotation system revealed by 16S rRNA gene 454-pyrosequencing

Authors
Lopes, AR; Manaia, CM; Nunes, OC;

Publication
FEMS MICROBIOLOGY ECOLOGY

Abstract
Crop rotation is a practice harmonized with the sustainable rice production. Nevertheless, the implications of this empirical practice are not well characterized, mainly in relation to the bacterial community composition and structure. In this study, the bacterial communities of two adjacent paddy fields in the 3rd and 4th year of the crop rotation cycle and of a nonseeded subplot were characterized before rice seeding and after harvesting, using 454-pyrosequencing of the 16S rRNA gene. Although the phyla Acidobacteria, Proteobacteria, Chloroflexi, Actinobacteria and Bacteroidetes predominated in all the samples, there were variations in relative abundance of these groups. Samples from the 3rd and 4th years of the crop rotation differed on the higher abundance of groups of presumable aerobic bacteria and of presumable anaerobic and acidobacterial groups, respectively. Members of the phylum Nitrospira were more abundant after rice harvest than in the previously sampled period. Rice cropping was positively correlated with the abundance of members of the orders Acidobacteriales and Solibacterales' and negatively with lineages such as Chloroflexi Ellin6529'. Studies like this contribute to understand variations occurring in the microbial communities in soils under sustainable rice production, based on real-world data.

2014

An Ordered Approach to Minimum Completion Time in Unrelated Parallel-Machines for the Makespan Optimization

Authors
Santos, ASE; Madureira, AM; Varela, MLR;

Publication
2014 SIXTH WORLD CONGRESS ON NATURE AND BIOLOGICALLY INSPIRED COMPUTING (NABIC)

Abstract
In the current global market organizations face uncertainties and shorter response time. In order to remain competitive many organizations adopted flexible resources capable of performing several operations with different performance capabilities. The unrelated parallel-machines makespan minimization problem (RmIiCmax) is known to be NP-hard or too complex to be solved exactly. Among the several heuristics used for solving this problem, it is possible to identify MCT (Minimum Completion Time) that allocates tasks in a random order to the minimum completion time machine. This paper proposes an ordered approach to the MCT heuristic. MOMCT (Modified Ordered Minimum Completion Time), which will order tasks in accordance to the mean difference of the completion time on each machine and the minimum completion time machine. The computational study demonstrated the improved performance of the proposed ordered approach to the MCT heuristic.

2014

The determinants of the internationalization speed of Portuguese university spin-offs: An empirical investigation

Authors
Teixeira, AAC; Coimbra, C;

Publication
Journal of International Entrepreneurship

Abstract
The speed of internationalization of firms has attracted considerable research in the last few decades. However, with regard to a particular type of firm, university spin-offs (USOs), this line of research is still incipient. A majority of the studies on USOs highlights their main features but does not focus on internationalization. Based on the responses from 111 Portuguese USOs, of which 78 are exporters, econometric estimations indicate that: (1) the internationalization speed of USOs is critically dependent on support from technology transfer offices; (2) in line with the “learning advantages of newness” perspective, younger Portuguese USOs reveal higher levels of entrepreneurial spirit and entrepreneurial capabilities, being in a better position to internationalize earlier than older USOs; (3) USOs that operate in microelectronics/robotics internationalize faster and earlier than USOs operating in ICT/software/digital media; and (4) in contrast with the literature on born globals/international new ventures, greater involvement in R&D activities slows down the early internationalization process of USOs. © 2014, Springer Science+Business Media New York.

2014

Cell-Free layer (CFL) measurements in complex geometries: Contractions and bifurcations

Authors
Novais, S; Pinho, D; Bento, D; Pinto, E; Yaginuma, T; Fernandes, CS; Garcia, V; Pereira, AI; Lima, J; Mujika, M; Dias, R; Arana, S; Lima, R;

Publication
Lecture Notes in Computational Vision and Biomechanics

Abstract
In this chapter we discuss the cell-free layer (CFL) developed adjacent to the wall of microgeometries containing complex features representative of the microcirculation, such as contractions, expansions, bifurcations and confluences. The microchannels with the different geometries were made of polydimethylsiloxane (PDMS) and we use optical techniques to evaluate the cell-free layer for red blood cells (RBCs) suspensions with different hematocrit (Hct). The images are captured using a high-speed video microscopy system and the thickness of the cell-free layer was measured using both manual and automatic image analysis techniques. The results show that in in vitro microcirculation, the hematocrit and the geometrical configuration have a major impact on the CFL thickness. In particular, the thickness of the cell-free layer increases as the fluid flows through a contraction–expansion sequence and that this increase is enhanced for lower hematocrit. In contrast, the flow rates tested in these studies did not show a clear influence on the CFL thickness. © Springer Science+Business Media Dordrecht 2014.

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