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Publications

2020

Optimal Design of Electric Bus Transport Systems With Minimal Total Ownership Cost

Authors
Lotfi, M; Pereira, P; Paterakis, NG; Gabbar, HA; Catalao, JPS;

Publication
IEEE ACCESS

Abstract
In this work, a generalized mathematical formulation is proposed to model a generic public transport system, and a mixed-integer linear programming (MILP) optimization is used to determine the optimal design of the system in terms of charging infrastructure deployment (with on-route and off-route charging), battery sizing, and charging schedules for each route in the network. Three case studies are used to validate the proposed model while demonstrating its universal applicability. First, the design of three individual routes with different characteristics is demonstrated. Then, a large-scale generic transport system with 180 routes, consisting of urban and suburban routes with varying characteristics is considered and the optimal design is obtained. Afterwards, the use of the proposed model for a long-term transport system planning problem is demonstrated by adapting the system to a 2030 scenario based on forecasted technological advancements. The proposed formulation is shown to be highly versatile in modeling a wide variety of components in an electric bus (EB) transport system and in achieving an optimal design with minimal TOC.

2020

The InBIO Barcoding Initiative Database: DNA barcodes of Portuguese Diptera 01

Authors
Ferreira, SA; Andrade, R; Goncalves, AR; Sousa, P; Pauperio, J; Fonseca, NA; Beja, P;

Publication
BIODIVERSITY DATA JOURNAL

Abstract
Background The InBIO Barcoding Initiative (IBI) Diptera 01 dataset contains records of 203 specimens of Diptera. All specimens have been morphologically identified to species level, and belong to 154 species in total. The species represented in this dataset correspond to about 10% of continental Portugal dipteran species diversity. All specimens were collected north of the Tagus river in Portugal. Sampling took place from 2014 to 2018, and specimens are deposited in the IBI collection at CIBIO, Research Center in Biodiversity and Genetic Resources. New information This dataset contributes to the knowledge on the DNA barcodes and distribution of 154 species of Diptera from Portugal and is the first of the planned IBI database public releases, which will make available genetic and distribution data for a series of taxa. All specimens have their DNA barcodes made publicly available in the Barcode of Life Data System (BOLD) online database and the distribution dataset can be freely accessed through the Global Biodiversity Information Facility (GBIF).

2020

Can learned frame prediction compete with block motion compensation for video coding?

Authors
Sulun, S; Tekalp, AM;

Publication
Signal, Image and Video Processing

Abstract

2020

BulbRobot - Inexpensive Open Hardware and Software Robot Featuring Catadioptric Vision and Virtual Sonars

Authors
Ferreira, J; Coelho, F; Sousa, A; Reis, LP;

Publication
FOURTH IBERIAN ROBOTICS CONFERENCE: ADVANCES IN ROBOTICS, ROBOT 2019, VOL 1

Abstract
This article proposes a feature-rich, open hardware, open software inexpensive robot based on a Waveshare AlphaBot 2. The proposal uses a Raspberry Pi and a chrome plated light bulb as a mirror to produce a robot with an omnidirectional vision (catadioptric) system. The system also tackles boot and network issues to allow for monitor-less programming and usage, thus further reducing usage costs. The OpenCV library is used for image processing and obstacles are identified based on their brightness and saturation in contrast to the ground. Our solution achieved acceptable framerates and near perfect object detection up to 1.5-m distances. The robot is usable for simple robotic demonstrations and educational purposes for its simplicity and flexibility.

2020

Favorable properties of Interior Point Method and Generalized Correntropy in power system State Estimation

Authors
Pesteh, S; Moayyed, H; Miranda, V;

Publication
ELECTRIC POWER SYSTEMS RESEARCH

Abstract
The paper provides the theoretical proof of earlier published experimental evidence of the favorable properties of a new method for State Estimation - the Generalized Correntropy Interior Point method (GCIP). The model uses a kernel estimate of the Generalized Correntropy of the error distribution as objective function, adopting Generalized Gaussian kernels. The problem is addressed by solving a constrained non-linear optimization program to maximize the similarity between states and estimated values. Solution space is searched through a special setting of a primal-dual Interior Point Method. This paper offers mathematical proof of key issues: first, that there is a theoretical shape parameter value for the kernel functions such that the feasible solution region is strictly convex, thus guaranteeing that any local solution is global or uniquely defined. Second, that a transformed system of measurement equations assures an even distribution of leverage points in the factor space of multiple regression, allowing the treatment of leverage points in a natural way. In addition, the estimated residual of GCIP model is not necessarily zero for critical (non-redundant) measurements. Finally, that the normalized residuals of critical sets are not necessarily equal in the new model, making the identification of bad data possible in these cases.

2020

DR|GRADUATE: Uncertainty-aware deep learning-based diabetic retinopathy grading in eye fundus images

Authors
Araújo, T; Aresta, G; Mendonça, L; Penas, S; Maia, C; Carneiro, A; Mendonça, AM; Campilho, A;

Publication
MEDICAL IMAGE ANALYSIS

Abstract
Diabetic retinopathy (DR) grading is crucial in determining the adequate treatment and follow up of patient, but the screening process can be tiresome and prone to errors. Deep learning approaches have shown promising performance as computer-aided diagnosis (CAD) systems, but their black-box behaviour hinders clinical application. We propose DR vertical bar GRADUATE, a novel deep learning-based DR grading CAD system that supports its decision by providing a medically interpretable explanation and an estimation of how uncertain that prediction is, allowing the ophthalmologist to measure how much that decision should be trusted. We designed DR vertical bar GRADUATE taking into account the ordinal nature of the DR grading problem. A novel Gaussian-sampling approach built upon a Multiple Instance Learning framework allow DR vertical bar GRADUATE to infer an image grade associated with an explanation map and a prediction uncertainty while being trained only with image-wise labels. DR vertical bar GRADUATE was trained on the Kaggle DR detection training set and evaluated across multiple datasets. In DR grading, a quadratic-weighted Cohen's kappa (kappa) between 0.71 and 0.84 was achieved in five different datasets. We show that high kappa values occur for images with low prediction uncertainty, thus indicating that this uncertainty is a valid measure of the predictions' quality. Further, bad quality images are generally associated with higher uncertainties, showing that images not suitable for diagnosis indeed lead to less trustworthy predictions. Additionally, tests on unfamiliar medical image data types suggest that DR vertical bar GRADUATE allows outlier detection. The attention maps generally highlight regions of interest for diagnosis. These results show the great potential of DR vertical bar GRADUATE as a second-opinion system in DR severity grading.

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