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Publications

2017

Bringing Bayesian networks to bedside: a web-based framework

Authors
Oliveira, R; Ferreira, J; Libânio, D; Dias, CC; Rodrigues, PP;

Publication
2017 IEEE 30TH INTERNATIONAL SYMPOSIUM ON COMPUTER-BASED MEDICAL SYSTEMS (CBMS)

Abstract
Bayesian networks are one of the most intuitive statistical models for both estimation, classification and prediction of patients' outcomes. However, the availability of inference software in clinical settings is still limited. This work presents preliminary steps towards the creation of simple web-based forms that can access a powerful Bayesian network inference engine, making the derived models usable at bedside by both the clinicians and the patients themselves.

2017

Modelling the relationship between heating energy use and indoor temperatures in residential buildings through Artificial Neural Networks considering occupant behavior

Authors
Magalhaes, SMC; Leal, VMS; Horta, IM;

Publication
ENERGY AND BUILDINGS

Abstract
The heating energy demand stated in energy performance certificates (EPC) and in other instruments used in the of evaluation of building's energy performance is usually determined assuming very specific (reference) indoor behavioral/heating patterns. Particularly, they tend to assume that households heat (nearly) the entire house to a "comfort" temperature during (nearly) all the heating season. However, several field studies have shown that there are major niches of the housing stock which do not follow this pattern (even the majority, in some geographical areas). Considering this matter, it would be interesting to build models able to estimate heating energy use values resultant from occupation and heating patterns different from those considered as "reference". This work aimed at producing tools to assess the relationship between heating energy use and indoor temperatures at different levels of occupant behavior (in terms of where, when and at what temperature households heat their dwellings). This relationship was expressed through models while still takes advantage of the information from the certificates. The work developed artificial neural networks (ANN) that characterize the relationship between heating energy use, indoor temperatures and the heating energy demand under reference conditions (typically available from energy rating/certificates) in the residential buildings, for different occupant behaviors heating patterns. Theoretically, these models can be applicable to any national geographical context. The data for building the ANNs was obtained from dynamic thermal building simulations using ESP-r, considering a large number of housing types and hypothetical occupation and heating patterns (i.e., which parts of the house are heated, when and at what temperature). From the analysis performed, it was possible to conclude that the developed ANN models proved to perform well (R-2 > 0.93) in estimating either heating energy use or indoor temperature, both at an individual and at the building stock level. This work may have important contributions in the energy planning practices regarding the residential building stock.

2017

Variability and Complexity in Software Design: Towards Quality through Modeling and Testing

Authors
Galster, M; Weyns, D; Goedicke, M; Zdun, U; Cunha, J; Chavarriaga, J;

Publication
ACM SIGSOFT Softw. Eng. Notes

Abstract
Today's software systems must accommodate a wide range of usage and deployment scenarios. The increasing size and heterogeneity of software-intensive systems, dynamic and critical operating conditions, fast moving and highly competitive markets, and increasingly powerful and versatile hardware makes it more and more difficult to handle the additional complexity in design caused by variability. This paper reports results of the Second International Workshop on Variability and Complexity in Software Design. It also outlines directions the field might move in the future.

2017

Multi-Period Modeling of Behind-the-Meter Flexibility

Authors
Pinto, R; Matos, MA; Bessa, RJ; Gouveia, J; Gouveia, C;

Publication
2017 IEEE MANCHESTER POWERTECH

Abstract
Reliable and smart information on the flexibility provision of Home Energy Management Systems (HEMS) represents great value for Distribution System Operators and Demand/flexibility Aggregators while market agents. However, efficiently delimiting the HEMS multi-temporal flexibility feasible domain is a complex task. The algorithm proposed in this work is able to efficiently learn and define the feasibility search space endowing DSOs and aggregators with a tool that, in a reliable and time efficient faction, provides them valuable information. That information is essential for those agents to comprehend the fully grid operation and economic benefits that can arise from the smart management of their flexible assets. House load profile, photovoltaic (PV) generation forecast, storage equipment and flexible loads as well as pre-defined costumer preferences are accounted when formulating the problem. Support Vector Data Description (SVDD) is used to build a model capable of identifying feasible HEMS flexibility offers. The proposed algorithm performs efficiently when identifying the feasibility of multi-temporal flexibility offers.

2017

Power transformer failure prediction: Classification in imbalanced time series

Authors
Oliveira E.E.; Miguéis V.L.; Guimarães L.; Borges J.;

Publication
U.Porto Journal of Engineering

Abstract
This paper describes a study on applying data mining techniques to power transformer failure prediction. The data set used consisted not only on DGA tests, but also in other tests done to the transformer’s insulating oil. This dataset presented several challenges, such as highly imbalanced classes (common in failure prediction problems), and the temporal nature of the observations. To overcome these challenges, several techniques were applied for prediction and better understand the dataset. Pre-processing and temporality incorporation in the dataset is discussed. For prediction, a 1-class and 2-class SVM, decision trees and random forests, as well as a LSTM neural network were applied to the dataset. As the prediction performance was low (high false-positive rate), we conducted a test to ascertain if the amount of data collected was sufficient. Results indicate that the frequency of data collection was not adequate, hinting that the degradation period was shorter than the periodicity of data collection.

2017

FOSTERING EFFICIENT LEARNING IN THE TECHNICAL FIELD OF ROBOTICS BY CHANGING THE AUTONOMOUS DRIVING COMPETITION OF THE PORTUGUESE ROBOTICS OPEN

Authors
Costa, V; Resende, J; Sousa, P; Sousa, A; Lau, N; Reis, L;

Publication
10TH INTERNATIONAL CONFERENCE OF EDUCATION, RESEARCH AND INNOVATION (ICERI2017)

Abstract
Autonomous Vehicles are a topic of important research, also being visually appealing to the public and attractive to educators and researchers. The autonomous driving competition in the Portuguese Robotics Open tries to take advantage of this context but concerns arise from lack of participators. Participants mention the complexity of issues related to the challenge, the space occupied for the track and the budget needed for participation. This paper takes advantage of a realistic simulator under Gazebo/ROS, studies a new track design and proposes a change in the track. The analysis presented tries to ascertain if the new design facilitates the learning process that is intended for participants while keeping visual appeal for both the general public and the participants. The proposed setup for the rules and simulator is expected to address the mentioned concerns. The rule's modification and simulator are evaluated and tested, hinting that expected learning outcomes are encouraged and the track occupied area is reduced. Learning includes mobile robotics (discrete event system and continuous control), real time artificial image vision systems (2D at image recognition and processing of real world imagery seen in 3D perspective), general real world robotics such as mechanics, control, programming, batteries, systems thinking as well as transversal skills such as team cooperation, soft skills, etc. Shown results hint that the new track and realistic simulation are promising to foster learning and hopefully attract more competing teams.

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