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Publications

Publications by Joaquim João Sousa

2019

Scalable task clean-up assignment for multi-agents

Authors
Saraiva, AA; Costa, NJC; Sousa, JVM; De Araujo, TP; Fonseca Ferreira, NM; Valente, A;

Publication
Robotics Transforming the Future - Proceedings of the 21st International Conference on Climbing and Walking Robots and the Support Technologies for Mobile Machines, CLAWAR 2018

Abstract
This paper describes a group of robots for cleaning a simulated environment and proposes an efficient algorithm for navigation based on Pathfinding A *. No need for vision sensors. As a result it was observed that the robots can work cooperatively to clear the ground and that the navigation algorithm is effective in cleaning. In order to test its efficiency it was compared the combination of the Pathfinding A* algorithm and the decision algorithm proposed in this paper with Pathfinding A* and Euclidean distance, resulted in an improvement in time and distance traveled. © CLAWAR Association.

2019

MixAR: A Multi-Tracking Mixed Reality System to Visualize Virtual Ancient Buildings Aligned Upon Ruins

Authors
Adao, T; Padua, L; Narciso, D; Sousa, JJ; Agrellos, L; Peres, E; Magalhaes, L;

Publication
JOURNAL OF INFORMATION TECHNOLOGY RESEARCH

Abstract
MixAR, a full-stack system capable of providing visualization of virtual reconstructions seamlessly integrated in the real scene (e.g. upon ruins), with the possibility of being freely explored by visitors, in situ, is presented in this article. In addition to its ability to operate with several tracking approaches to be able to deal with a wide variety of environmental conditions, MixAR system also implements an extended environment feature that provides visitors with an insight on surrounding points-of-interest for visitation during mixed reality experiences (positional rough tracking). A procedural modelling tool mainstreams augmentation models production. Tests carried out with participants to ascertain comfort, satisfaction and presence/immersion based on an in-field MR experience and respective results are also presented. Ease to adapt to the experience, desire to see the system in museums and a raised curiosity and motivation contributed as positive points for evaluation. In what regards to sickness and comfort, the lowest number of complaints seems to be satisfactory. Models' illumination/re-lightning must be addressed in the future to improve the user's engagement with the experiences provided by the MixAR system.

2019

Vineyard Variability Analysis through UAV-Based Vigour Maps to Assess Climate Change Impacts

Authors
Padua, L; Marques, P; Adao, T; Guimaraes, N; Sousa, A; Peres, E; Sousa, JJ;

Publication
AGRONOMY-BASEL

Abstract
Climate change is projected to be a key influence on crop yields across the globe. Regarding viticulture, primary climate vectors with a significant impact include temperature, moisture stress, and radiation. Within this context, it is of foremost importance to monitor soils' moisture levels, as well as to detect pests, diseases, and possible problems with irrigation equipment. Regular monitoring activities will enable timely measures that may trigger field interventions that are used to preserve grapevines' phytosanitary state, saving both time and money, while assuring a more sustainable activity. This study employs unmanned aerial vehicles (UAVs) to acquire aerial imagery, using RGB, multispectral and thermal infrared sensors in a vineyard located in the Portuguese Douro wine region. Data acquired enabled the multi-temporal characterization of the vineyard development throughout a season through the computation of the normalized difference vegetation index, crop surface models, and the crop water stress index. Moreover, vigour maps were computed in three classes (high, medium, and low) with different approaches: (1) considering the whole vineyard, including inter-row vegetation and bare soil; (2) considering only automatically detected grapevine vegetation; and (3) also considering grapevine vegetation by only applying a normalization process before creating the vigour maps. Results showed that vigour maps considering only grapevine vegetation provided an accurate representation of the vineyard variability. Furthermore, significant spatial associations can be gathered through (i) a multi-temporal analysis of vigour maps, and (ii) by comparing vigour maps with both height and water stress estimation. This type of analysis can assist, in a significant way, the decision-making processes in viticulture.

2018

DEFORMATION MONITORING OF THE NORTHERN SECTOR OF THE VALENCIA BASIN (E SPAIN) USING PS-INSAR (1993-2010)

Authors
Ruiz Armenteros, AM; Manuel Delgado, JM; Ballesteros Navarro, BJ; Lazecky, M; Bakon, M; Sousa, JJ;

Publication
IGARSS 2018 - 2018 IEEE INTERNATIONAL GEOSCIENCE AND REMOTE SENSING SYMPOSIUM

Abstract
Synthetic Aperture Radar Interferometry (InSAR) is a remote sensing technique very effective for the measurement of small displacements of the Earth's surface over large areas at a very low cost in comparison with conventional geodetic techniques. Advanced InSAR time series (Multi-Temporal InSAR or MT-InSAR) algorithms for monitoring and investigating surface displacement on Earth are based on conventional radar interferometry. These techniques allow us to measure deformation with uncertainties of one millimeter per year, interpreting time series of interferometric phases at coherent point scatterers (PS) without the need for human or special equipment presence. By applying InSAR processing techniques to a series of radar images over the same region, it is possible to monitor large areas and detect vertical displacements of ground, and infrastructures on the ground, and therefore identify abnormal or excessive movements indicating potential problems requiring detailed ground investigation. In this paper, we apply the PS-InSAR technique to a dataset of ERS-1/2 and Envisat radar images covering the period 1993-2010, to monitor the northern sector of the Valencia basin (Valencia city and its surroundings). Some subsiding areas were detected, with rates up to -5 mm/yr, whose causes are being investigated.

2019

Landslide movement monitoring with ALOS-2 SAR data

Authors
Liu, G; Guo, HD; Perski, Z; Fan, JH; Sousa, JJ; Yan, SY; Tang, PP;

Publication
THIRD INTERNATIONAL CONFERENCE ON ENERGY ENGINEERING AND ENVIRONMENTAL PROTECTION

Abstract
Landslide is a hazard that threaten the people who lives in the mountain area, it comes active especially rainy seasons and causes a large number of casualties every year. The movement of the slope is an indicator of activity of the landslide, it is helpful to capture the precursor of the activity, the monitoring of the movement of the slope is very important. However it is a difficult problem due to complex topography, cloudy and rainy weather for optical sensors, In this paper we will show the capability of up-to-date Advanced Land Observing Satellite-2 (ALOS-2) Synthetic Aperture Radar (SAR) data in monitoring the movement of the landslide which located in south China, which can capture the fast and slow movement with different spatial and temporal baseline combination, the results shows that the L-band SAR data has its advantage in monitoring the movement of the landslides especially in the low latitude, cloudy and rainy area.

2019

Phenolic composition of vine leaves infusions produced from different Portuguese and Spanish Vitis vinifera L. varieties

Authors
Jordao, AM; Sousa, J; Correia, AC; Valdes, ME; Nunes, FM; Cosme, F;

Publication
41ST WORLD CONGRESS OF VINE AND WINE

Abstract
The main object of the present study was to analyze the phenolic composition of vine leaves infusions prepared from 8 different Portuguese (Fernao Pires, Touriga Franca, Tinta Roriz, Encruzado, Touriga Nacional, Rufete, Baga, and Siria) and Spanish (Pardina, Cayetana, Garnacha, Ciguente, Eva, Tempranillo, Macabeo and Verdelho) Vitis vinifera L. varieties. In general, a wide range of phenolic content were obtained from the vine leaves infusions according to the vine variety used. Thus, for total phenolic content the values ranged from 18 to 37 mg/L for the infusions produced from Portuguese varieties, while for Spanish varieties the values ranged from 14 to 37 mg/L. Vine leaves infusions obtained from Touriga Franca and Pardina varieties showed the highest total phenolic content. As a consequence of phenolic composition, chromatic characteristics (L*, a* and b*) of vine leaves infusions were also analyzed. Finally, it was also detected different individual phenolic compounds, such as, coutaric acid, trans-caftaric acid, quercetin-3-O-glucoside, rutin and 3 different anthocyanins from the different vine leaves infusions. All of the results obtained in this work show that vine leaves infusion may be an interesting alternative source of phenolic compounds for human diet.

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