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Publications

2017

Recent Advances in Image Processing Techniques for Automated Harvesting Purposes: A Review

Authors
Pereira, CS; Morais, R; Reis, MJCS;

Publication
PROCEEDINGS OF THE 2017 INTELLIGENT SYSTEMS CONFERENCE (INTELLISYS)

Abstract
Image processing has been proved to be an effective tool for analysis in various human activity areas, namely, agricultural applications. Interpreting a digital color image of fruit orchard captured in field environment is extremely challenging due to adverse weather conditions, luminance variability and the presence of dust, insects and other unavoidable image noises. The purpose of this survey is to categorize and briefly review the literature on computer analysis of fruit images in agricultural operations, which comprises more than 60 papers published in the last 10 years. With the aim to perform applied research in agricultural imaging, this paper intends to focus on advanced image processing and analysis techniques used in applications for detection and classifications of fruits, developed in the last decade. For the reviewed techniques, some performance evaluation metrics achieved in various experiments are emphasized to help the researchers when making choices and develop new computer vision applications in fruit images.

2017

PHASE ANGLE PREDICTS ARTERIAL STIFFNESS AND VASCULAR CALCIFICATION IN PERITONEAL DIALYSIS PATIENTS

Authors
Sarmento Dias, M; Santos Araujo, C; Poinhos, R; Oliveira, B; Sousa, M; Simoes Silva, L; Soares Silva, I; Correia, F; Pestana, M;

Publication
PERITONEAL DIALYSIS INTERNATIONAL

Abstract
Objectives: Fluid overload (FO) is frequently present in peritoneal dialysis (PD) patients and is associated with markers of malnutrition, inflammation, and atherosclerosis/calcification (MIAC) syndrome. We examined the relationships in stable PD patients between phase angle (PhA) and the spectrum of uremic vasculopathy including vascular calcification and arterial stiffness and between PhA and changes in serum fetuin-A levels. Methods: Sixty-one stable adult PD patients were evaluated in a cross-sectional study (ST1). Phase angle was measured by multifrequency bioimpedance analysis (InbodyS10, Biospace, Korea) at 50 kHz. Augmentation index (AI), a surrogate marker of arterial stiffness, was assessed by digital pulse amplitude tonometry (Endo PAT, Itamar Medical, Caesarea, Israel). Vascular calcification was assessed by simplified calcification score (SCS). Serum fetuin-A levels were measured by ELISA (Thermo scientific; Waltham, MA, USA). Serum albumin was used as a nutritional marker, and serum C-reactive protein (CRP) was used as an inflammatory marker. The same assessments were carried out longitudinally (ST2) in the first 33 patients who completed 1 year of evaluation in ST1. Results: In ST1, patients with PhA < 6(omicron) had higher CRP levels, AI, and SCS and lower serum albumin and fetuin-A levels, in comparison with patients with PhA >= 6(omicron). In addition, PhA was a predictor of both AI (beta = -0.351, p = 0.023) and SCS >= 3 (EXP (B) = 0.243, p = 0.005). In ST2, the increase of PhA over time was associated with decreases in both AI (r = -0.378, p = 0.042) and CRP levels (r= -0.426, p = 0.021), as well as with the increase in serum fetuin-A levels (r = 0.411, p = 0.030). Conclusions: Phase angle predicts both arterial stiffness and vascular calcification in stable PD patients.

2017

Space- time refraction of light in time dependent media: the analogue within the analogue

Authors
Guerreiro, A; Mendonca, JT; Costa, JC; Gomes, M; Silva, NA;

Publication
THIRD INTERNATIONAL CONFERENCE ON APPLICATIONS OF OPTICS AND PHOTONICS

Abstract
The problem of electromagnetic wave propagation in time varying media is very old, but in recent years it has been revisited at a more fundamental level leading to the introduction of several new concepts, such as Time Refraction. These concepts explore the symmetries between space and time and can be transposed to different fields by establishing powerful analogies between effects in Electrodynamics, Optics and problems in Quantum Cosmology and in what is sometimes called Analogue Gravity. We examine the alteration of the ordinary (spatial) Fresnel laws of refraction at the interface between two media when the optical properties of one of the media varies in time.

2017

Preface

Authors
Sayed Mouchaweh, M; Bouchachia, H; Gama, J; Ribeiro, RP;

Publication
CEUR Workshop Proceedings

Abstract

2017

Time-domain electromagnetic method applied on penacova-régua-verin fault and adjacent zones. Sector of vila pouca de aguiar

Authors
Silva, R; Moura, R; Sant’Ovaia, H; Miranda, J;

Publication
International Multidisciplinary Scientific GeoConference Surveying Geology and Mining Ecology Management, SGEM

Abstract
The present work shows some results obtained by the Time-Domain Electromagnetic Method (TDEM) to help characterize the geology and Penacova- Régua-Verin fault structure in the Vila Pouca de Aguiar sector. The Fault is an important tardi-variscan structure with NNE-SSW direction, more than 500 km long, extending from the North of Spain until near Nazaré. The application of the TDEM method aimed to acquire data towards obtaining profiles of subsurface electrical resistivity in the zone affected by the fault and adjacent terrain. Electrical resistivity profiles, resulting from the combination of individual soundings, were performed in the SW quadrant of 6D-Vila Pouca de Aguiar of Carta Geológica de Portugal sheet, at a scale of 1/50 000, along Penacova-Régua-Verin Fault and perpendicularly, with WNW-ESE orientation, in the western sector of the fault. Some confirmation and preliminary models were accomplished using the results obtained by other authors, allowing to verify the validity of the obtained inverted data. The method responded in accordance with the conceptual model but allowed the additional distinction between alteration zones and apparently identical lithologies. Overall, three main blocks were identified, the most superficial shows high resistivities and low thickness. The second block has lower resistivity values due to the influence of the water level at this depth. In the third block, more oscillatory characteristics were identified throughout the various surveys. Although, in general, its high thickness and high values of electrical resistivity were highlighted. However, one of the obstacles in the implementation of the method was the presence of wind farms in Northern Portugal, bridges, metal fences, as well as power lines and high voltage pylons that produce electromagnetic noise and thus interfere with the readings obtained.

2017

Approach for Supervising Self-localization Processes in Mobile Robots

Authors
Farias, PCMA; Sousa, I; Sobreira, H; Moreira, AP;

Publication
PROGRESS IN ARTIFICIAL INTELLIGENCE (EPIA 2017)

Abstract
In this paper it will be presented a proposal of a supervisory approach to be applied to the global localization algorithms in mobile robots. One of the objectives of this work is the increase of the robustness in the estimation of the robot's pose, favoring the anticipated detection of the loss of spatial reference and avoiding faults like tracking derail. The proposed supervisory system is also intended to increase accuracy in localization and is based on two of the most commonly used global feature based localization algorithms for pose tracking in robotics: Augmented Monte Carlo Localization (AMCL) and Perfect Match (PM). The experimental platform was a robotic wheelchair and the navigation used the sensory data from encoders and laser rangers. The software was developed using the ROS framework. The results showed the validity of the proposal, since the supervisor was able to coordinate the action of the AMCL and PM algorithms, benefiting the robot's localization system with the advantages of each one of the methods.

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