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Publicações

2019

Sparse Multi-Bending Snakes

Autores
Araujo, RJ; Fernandes, K; Cardoso, JS;

Publicação
IEEE TRANSACTIONS ON IMAGE PROCESSING

Abstract
Active contour models are one of the most emblematic algorithms of computer vision. Their strong theoretical foundations and high user interoperahility turned them into a reference approach for object segmentation and tracking tasks. A high number of modifications have already been proposed in order to overcome the known problems of traditional snakes, such as initialization dependence and poor convergence to concavities. In this paper, we address the scenario where the user wants to segment an object that has multiple dynamic regions but some of them do not correspond to the true object boundary. We propose a novel parametric active contour model, the Sparse Multi-Bending snake, which is capable of dividing the contour into a set of contiguous regions with different bending properties. We derive a new energy function that induces such behavior and presents a group optimization strategy that can be used to find the optimal bending resistance parameter for each point of the contour. We show the flexibility of our model in a set of synthetic images. In addition, we consider two real applications, lung segmentation in Computerized Tomography data and hand segmentation in depth images. We show how the proposed method is able to improve the segmentations obtained in both applications, when compared with other active contour models.

2019

Spatiotemporal model for estimating electric vehicles adopters

Autores
Rodrigues, JL; Bolognesi, HM; Melo, JD; Heymann, F; Soares, FJ;

Publicação
ENERGY

Abstract
The use of fossil fuel vehicles is one of the factors responsible for the degradation of air quality in urban areas. In order to reduce levels of air pollution in metropolitan areas, several countries have encouraged the use of electric vehicles in the cities. However, due to the high investment costs in this class of vehicles, it is expected that the spatial distribution of electric vehicles' adopters will be heterogeneous. The additional charging power required by electric vehicles' batteries can change operation and expansion planning of power distribution utilities. In addition, urban planning agencies should analyze the most suitable locations for the construction of electric vehicle recharging stations. Thus, in order to provide information for the planning of electric mobility services in the city, this paper presents a spatiotemporal model for estimating the rate of electric vehicles' adopters per subareas. Results are spatial databases that can be viewed in geographic information systems to observe regions with greater expectancy of residential electric vehicle adopters. These outcomes can help utilities to develop new services that ground on the rising availability of electric mobility in urban zones.

2019

A Kernel Principal Component Regressor for LPV System Identification

Autores
dos Santos, PL; Perdicoulis, TPA;

Publicação
IFAC PAPERSONLINE

Abstract
This article describes a Kernel Principal Component Regressor (KPCR) to identify Auto Regressive eXogenous (ARX) Linear Parmeter Varying (LPV) models. The new method differs from the Least Squares Support Vector Machines (LS-SVM) algorithm in the regularisation of the Least Squares (LS) problem, since the KPCR only keeps the principal components of the Gram matrix while LS-SVM performs the inversion of the same matrix after adding a regularisation factor. Also, in this new approach, the LS problem is formulated in the primal space but it ends up being solved in the dual space overcoming the fact that the regressors are unknown. The method is assessed and compared to the LS-SVM approach through 2 Monte Carlo (MC) experiments. Every experiment consists of 100 runs of a simulated example, and a different noise level is used in each experiment,with Signal to Noise Ratios of 20db and 10db, respectively. The obtained results are twofold, first the performance of the new method is comparable to the LS-SVM, for both noise levels, although the required calculations are much faster for the KPCR. Second, this new method reduces the dimension of the primal space and may convey a way of knowing the number of basis functions required in the Kernel. Furthermore, having a structure very similar to LS-SVM makes it possible to use this method in other types of models, e.g. the LPV state-space model identification.

2019

Machine learning for streaming data: state of the art, challenges, and opportunities

Autores
Gomes, HM; Read, J; Bifet, A; Barddal, JP; Gama, J;

Publicação
SIGKDD Explorations

Abstract

2019

RT-WiFi Approach to Handle Real-Time Communication: An Experimental Evaluation

Autores
Betiol Junior, J; Costa, R; Moraes, R; Rech, L; Vasques, F;

Publicação
AD-HOC, MOBILE, AND WIRELESS NETWORKS (ADHOC-NOW 2019)

Abstract
WiFi (IEEE 802.11 standard) networks are widely used to support real-time (RT) applications, from home environment systems to complex networked control systems (NCS). Nevertheless, the Quality of Service (QoS) extensions incorporated into the standard are still unable to guarantee some relevant RT communications requirements. This paper presents an experimental validation of the RT-WiFi architecture that was recently proposed to deal with RT communication requirements and analysed through simulation. The experimental results demonstrate the feasibility of implementing the RT-WiFi architecture and improving the QoS level of communications through a comparative analysis with the EDCA (Enhanced Distributed Channel Access) mechanism, which is a mechanism incorporated in the IEEE 802.11 standard to provide different levels of transmission priority of different types of traffic.

2019

Industrial IoT Smartbox for the Shop Floor

Autores
Malhao, S; Dionisio, R; Torres, P;

Publicação
Proceedings of the 2019 5th Experiment at International Conference, exp.at 2019

Abstract
Constant search for efficiency and productivity has led to innovation on the factory shop floor, representing an evolution of the current production systems combined with new technologies of industrial automation and information technology. This work presents an experimental demo of a smartbox for Industry 4.0 scenarios, allowing sensing, monitoring and data acquisition. We have tested two different approaches, depending on the communication protocol used for real time applications: OPC UA or MQTT. Raspberry Pi's platform act as an OPC UA server or MQTT broker, respectively. From the measurements, data stored in a cloud server can be accessed remotely with improved security and visualized from a computer dashboard. One of the conclusions that can be drawn is that both protocols allow data from the smartbox to be stored and easily monitored from a smartphone application or a computer web interface. MQTT is a good option in communications requiring very low bandwidth. However, there is a lack of suitable libraries to program alarm features for OPC UA Servers. © 2019 IEEE.

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