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Publicações

2022

The Efficiency of Foliar Kaolin Spray Assessed through UAV-Based Thermal Infrared Imagery

Autores
Padua, L; Bernardo, S; Dinis, LT; Correia, C; Moutinho Pereira, J; Sousa, JJ;

Publicação
REMOTE SENSING

Abstract
The water content in an agricultural crop is of crucial importance and can either be estimated through proximal or remote sensing techniques, allowing better irrigation scheduling and avoiding extreme water stress periods. However, the current climate change context is increasing the use of eco-friendly practices to reconcile water management and thermal protection from sunburn. These approaches aim to mitigate summer stress factors (high temperature, high radiation, and water shortage) and improve the plants' thermal efficiency. In this study, data from unmanned aerial vehicles (UAVs) were used to monitor the efficiency of foliar kaolin application (5%) in a commercial vineyard. Thermal infrared imagery (TIR) was used to compare the canopy temperature of grapevines with and without kaolin and to compute crop water stress and stomatal conductance indices. The gas exchange parameters of single leaves were also analysed to ascertain the physiological performance of vines and validate the UAV-based TIR data. Generally, plants sprayed with kaolin presented a lower temperature compared to untreated plants. Moreover, UAV-based data also showed a lower water stress index and higher stomatal conductance, which relate to eco-physiological measurements carried out in the field. Thus, the suitability of UAV-based TIR data proved to be a good approach to monitor entire vineyards in regions affected by periods of heatwaves, as is the case of the analysed study area.

2022

Image Recognition-Based Architecture to Enhance Inclusive Mobility of Visually Impaired People in Smart and Urban Environments

Autores
Paiva, S; Amaral, A; Goncalves, J; Lima, R; Barreto, L;

Publicação
SUSTAINABILITY

Abstract
The demographic growth that we have witnessed in recent years, which is expected to increase in the years to come, raises emerging challenges worldwide regarding urban mobility, both in transport and pedestrian movement. The sustainable development of cities is also intrinsically linked to urban planning and mobility strategies. The tasks of navigation and orientation in cities are something that we resort to today with great frequency, especially in unknown cities and places. Current navigation solutions refer to the precision aspect as a big challenge, especially between buildings in city centers. In this paper, we focus on the segment of visually impaired people and how they can obtain information about where they are when, for some reason, they have lost their orientation. Of course, the challenges are different and much more challenging in this situation and with this population segment. GPS, a technique widely used for navigation in outdoor environments, does not have the precision we need or the most beneficial type of content because the information that a visually impaired person needs when lost is not the name of the street or the coordinates but a reference point. Therefore, this paper includes the proposal of a conceptual architecture for outdoor positioning of visually impaired people using the Landmark Positioning approach.

2022

Linear and nonlinear systems in continuous time: application to power converters

Autores
Silveira, AM; de Castro, R; Araújo, RE;

Publicação
Encyclopedia of Electrical and Electronic Power Engineering: Volumes 1-3

Abstract
Modeling is a key step in the design of energy and control systems. It allows us to simulate and predict the behavior of electronics converters, even before constructing them. This is instrumental, for example, for sizing, component selection and preliminary validation of the converter's functionality. It also enables us to design model-based controllers for the converter and regulate the amount of transferred power, which can be done using simulation tools. This article introduces the main tools employed in the mathematical modeling of power converters, with a particular focus on linear approximations and average models. © 2023 Elsevier Inc. All rights reserved.

2022

A Hybrid Approach for an Interpretable and Explainable Intrusion Detection System

Autores
Dias, T; Oliveira, N; Sousa, N; Praca, I; Sousa, O;

Publicação
INTELLIGENT SYSTEMS DESIGN AND APPLICATIONS, ISDA 2021

Abstract
Cybersecurity has been a concern for quite a while now. In the latest years, cyberattacks have been increasing in size and complexity, fueled by significant advances in technology. Nowadays, there is an unavoidable necessity of protecting systems and data crucial for business continuity. Hence, many intrusion detection systems have been created in an attempt to mitigate these threats and contribute to a timelier detection. This work proposes an interpretable and explainable hybrid intrusion detection system, which makes use of artificial intelligence methods to achieve better and more long-lasting security. The system combines experts' written rules and dynamic knowledge continuously generated by a decision tree algorithm as new shreds of evidence emerge from network activity.

2022

Turning the Tables: Biased, Imbalanced, Dynamic Tabular Datasets for ML Evaluation

Autores
Alves, D; Bizarro, P; Cruz, A; Gama, J; Jesus, S; Pombal, J; Ribeiro, R; Saleiro, P;

Publicação
Advances in Neural Information Processing Systems 35

Abstract

2022

A Survey of Emergencies Management Systems in Smart Cities

Autores
Costa, DG; Peixoto, JPJ; Jesus, TC; Portugal, P; Vasques, F; Rangel, E; Peixoto, M;

Publicação
IEEE ACCESS

Abstract
The rapid urbanization process in the last century has deeply changed the way we live and interact with each other. As most people now live in urban areas, cities are experiencing growing demands for more efficient and sustainable public services that may improve the perceived quality of life, specially with the anticipated impacts of climatic changes. In this already complex scenario with increasingly overcrowded urban areas, different types of emergency situations may happen anywhere and anytime, with unpredictable costs in human lives and economic losses. In order to cope with unexpected and potentially dangerous emergencies, smart cities initiatives have been developed in different cities, addressing multiple aspects of emergencies detection, alerting, and mitigation. In this context, this article surveys recent smart city solutions for crisis management, proposing definitions for emergencies-oriented systems and classifying them according to the employed technologies and provided services. Additionally, recent developments in the domains of Internet of Things, Artificial Intelligence and Big Data are also highlighted when associated to the management of urban emergencies, potentially paving the way for new developments while classifying and organizing them according to different criteria. Finally, open research challenges will be identified, indicating promising trends and research directions for the coming years.

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