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Publications

2022

Decoding Reinforcement Learning for newcomers

Authors
Neves, F; F. Reis, M; Andrade, G; Aguiar, AP; Pinto, AM;

Publication

Abstract
<p>An intelligible step-by-step Reinforcement Learning (RL) problem formulation and the availability of an easy-to-use demonstrative toolbox for students at various levels (e.g., undergraduate, bachelor, master, doctorate), researchers and educators. This tool facilitates the familiarization with the key concepts of RL, its problem formulation and implementation. The results demonstrated in this paper are produced by a Python program that is released open-source, along with other lecture materials to reduce the learning barriers in such innovative research topic in robotics.</p> <p>The RL paradigm is showing promising results as a generic purpose framework for solving decision-making problems (e.g., robotics, games, finance). In this work, RL is used for solving a robotics 2D navigational problem where the robot needs to avoid collisions with obstacles while aiming to reach a goal point. A navigational problem is simple and convenient for educational purposes, since the outcome is unambiguous (e.g., the goal is reached or not, a collision happened or not). Thus, the intent is to accelerate the adoption of RL techniques in the field of mobile robotics.</p> <p>Motivate and promote the adoption of RL techniques to solve decision-making problems, specifically in robotics. </p> <p>Due to a lack of accessible educational and demonstrative toolboxes concerning the field of RL, this work combines theoretical exposition with an accessible open-source graphical interactive toolbox to facilitate the apprehension.</p> <p>This study aims to reduce the learning barriers and inspire young students, researchers and educators to use RL as an obvious tool to solve robotics problems.</p>

2022

ScraPE - An Automated Tool for Programming Exercises Scraping

Authors
Queirós, R;

Publication
11th Symposium on Languages, Applications and Technologies, SLATE 2022, July 14-15, 2022, Universidade da Beira Interior, Covilhã, Portugal.

Abstract
Learning programming boils down to the practice of solving exercises. However, although there are good and diversified exercises, these are held in proprietary systems hindering their interoperability. This article presents a simple scraping tool, called ScraPE, which through a navigation, interaction and data extraction script, materialized in a domain-specific language, allows extracting the data necessary from Web pages – typically online judges – to compose programming exercises in a standard language. The tool is validated by extracting exercises from a specific online judge. This tool is part of a larger project where the main objective is to provide programming exercises through a simple GraphQL API. © Ricardo Queirós.

2022

Vineyard classification using OBIA on UAV-based RGB and multispectral data: A case study in different wine regions

Authors
Pádua, L; Matese, A; Di Gennaro, SF; Morais, R; Peres, E; Sousa, JJ;

Publication
COMPUTERS AND ELECTRONICS IN AGRICULTURE

Abstract
Vineyard classification is an important process within viticulture-related decision-support systems. Indeed, it improves grapevine vegetation detection, enabling both the assessment of vineyard vegetative properties and the optimization of in-field management tasks. Aerial data acquired by sensors coupled to unmanned aerial vehicles (UAVs) may be used to achieve it. Flight campaigns were conducted to acquire both RGB and multispectral data from three vineyards located in Portugal and in Italy. Red, green, blue and near infrared orthorectified mosaics resulted from the photogrammetric processing of the acquired data. They were then used to calculate RGB and multispectral vegetation indices, as well as a crop surface model (CSM). Three different supervised machine learning (ML) approaches-support vector machine (SVM), random forest (RF) and artificial neural network (ANN)-were trained to classify elements present within each vineyard into one of four classes: grapevine, shadow, soil and other vegetation. The trained models were then used to classify vineyards objects, generated from an object-based image analysis (OBIA) approach, into the four classes. Classification outcomes were compared with an automatic point-cloud classification approach and threshold-based approaches. Results shown that ANN provided a better overall classification performance, regardless of the type of features used. Features based on RGB data showed better performance than the ones based only on multispectral data. However, a higher performance was achieved when using features from both sensors. The methods presented in this study that resort to data acquired from different sensors are suitable to be used in the vineyard classification process. Furthermore, they also may be applied in other land use classification scenarios.

2022

Dynamic remuneration of electricity consumers flexibility

Authors
Ribeiro, C; Pinto, T; Vale, Z; Baptista, J;

Publication
ENERGY REPORTS

Abstract
This paper proposes a decision support model to define electricity consumers' remuneration structures when providing consumption flexibility, optimized for different load regimes. The proposed model addresses the remuneration of consumers when participating in demand response programs, benefiting or penalizing those who adjust their consumption when needed. The model defines dynamic remuneration values with different natures for the aggregator (e.g. flexibility aggregator or curtailment service provider) and for the consumer. The preferences and perspective of both are considered, by incorporating variables that represent the energy price, the energy production and the flexibility of consumers. The validation is performed using real data from the Iberian market, and results enable to conclude that the proposed model adapts the remuneration values in a way that it is increased according to the consumers' elastic, while being reduced when the generation is higher. Consequently, the model boosts the active consumer participation when flexibility is required, while reaching a solution that represents an acceptable g tradeoff between the aggregators and the consumers. (C) 2022 The Authors. Published by Elsevier Ltd.

2022

Artificial Intelligence for Upper Gastrointestinal Endoscopy: A Roadmap from Technology Development to Clinical Practice

Authors
Renna, F; Martins, M; Neto, A; Cunha, A; Libanio, D; Dinis-Ribeiro, M; Coimbra, M;

Publication
DIAGNOSTICS

Abstract
Stomach cancer is the third deadliest type of cancer in the world (0.86 million deaths in 2017). In 2035, a 20% increase will be observed both in incidence and mortality due to demographic effects if no interventions are foreseen. Upper GI endoscopy (UGIE) plays a paramount role in early diagnosis and, therefore, improved survival rates. On the other hand, human and technical factors can contribute to misdiagnosis while performing UGIE. In this scenario, artificial intelligence (AI) has recently shown its potential in compensating for the pitfalls of UGIE, by leveraging deep learning architectures able to efficiently recognize endoscopic patterns from UGIE video data. This work presents a review of the current state-of-the-art algorithms in the application of AI to gastroscopy. It focuses specifically on the threefold tasks of assuring exam completeness (i.e., detecting the presence of blind spots) and assisting in the detection and characterization of clinical findings, both gastric precancerous conditions and neoplastic lesion changes. Early and promising results have already been obtained using well-known deep learning architectures for computer vision, but many algorithmic challenges remain in achieving the vision of AI-assisted UGIE. Future challenges in the roadmap for the effective integration of AI tools within the UGIE clinical practice are discussed, namely the adoption of more robust deep learning architectures and methods able to embed domain knowledge into image/video classifiers as well as the availability of large, annotated datasets.

2022

Generation of Document Type Exercises for Automated Assessment

Authors
Leal, JP; Queirós, R; Primo, M;

Publication
SLATE

Abstract
This paper describes ongoing research to develop a system to automatically generate exercises on document type validation. It aims to support multiple text-based document formalisms, currently including JSON and XML. Validation of JSON documents uses JSON Schema and validation of XML uses both XML Schema and DTD. The exercise generator receives as input a document type and produces two sets of documents: valid and invalid instances. Document types written by students must validate the former and invalidate the latter. Exercises produced by this generator can be automatically accessed in a state-of-the-art assessment system. This paper details the proposed approach and describes the design of the system currently being implemented.

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