Luis Rato

Prof. Luis Rato

Computer Science, University of Évora, Évora, Portugal
orcid
Algoritmi research Center, Associate Professor at Computer S...

Research Focus & Metrics

Academic Career Length

30Years (1997-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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1 August 2022 in BioMedical Engineering OnLine
Verified
Journal Article
Open access
PDF file
SVSahan M. Vijithananda
Sahan M. Vijithananda
MJMohan Mohan L. Jayatilake
Mohan Mohan L. Jayatilake
BHBadra Hewavithana
Badra Hewavithana
Teresa GonçalvesTeresa Gonçalves
Teresa Gonçalves
Luis RatoLuis Rato
Luis Rato
KDKaruna D. Dissanayake
Karuna D. Dissanayake
Background: Diffusion-weighted (DW) imaging is a well-recognized magnetic resonance imaging (MRI) technique that is being routinely used in brain examinations in modern clinical radiology practices. This study focuses on extracting demographic and texture features from MRI Apparent Diffusion Coefficient (ADC) images of human brain tumors, identifying the distribution patterns of each feature and applying Machine Learning (ML) techniques to differentiate malignant from benign brain tumors. Methods: This prospective study was carried out using 1599 labeled MRI brain ADC image slices, 995 malignant, 604 benign from 195 patients who were radiologically diagnosed and histopathologically confirmed as brain tumor patients. The demographics, mean pixel values, skewness, kurtosis, features of Grey Level Co-occurrence Matrix (GLCM), mean, variance, energy, entropy, contrast, homogeneity, correlation, prominence and shade, were extracted from MRI ADC images of each patient. At the feature selection phase, the validity of the extracted features were measured using ANOVA f-test. Then, these features were used as input to several Machine Learning classification algorithms and the respective models were assessed. Results: According to the results of ANOVA f-test feature selection process, two attributes: skewness (3.34) and GLCM homogeneity (3.45) scored the lowest ANOVA f-test scores. Therefore, both features were excluded in continuation of the experiment. From the different tested ML algorithms, the Random Forest classifier was chosen to build the final ML model, since it presented the highest accuracy. The final model was able to predict malignant and benign neoplasms with an 90.41% accuracy after the hyper parameter tuning process. Conclusions: This study concludes that the above mentioned features (except skewness and GLCM homogeneity) are informative to identify and differentiate malignant from benign brain tumors. Moreover, they enable the development of a high-performance ML model that has the ability to assist in the decision-making steps of brain tumor diagnosis process, prior to attempting invasive diagnostic procedures, such as brain biopsies.

8 September 2003 in IEEE Transactions on Control Systems Technology
Verified
Journal Article
Closed access
RNRui Neves-Silva
Rui Neves-Silva
JLJoao M Lemos
Joao M Lemos
Luis RatoLuis Rato
Luis Rato
Distributed collector solar fields are spatially distributed engineering systems, which aim at collecting and storing energy from solar radiation. They are formed by mirrors which concentrate direct incident sun light in a pipe where a fluid, able to accumulate thermic energy, flows. From the control point of view, the objective considered here consists of making the outlet oil temperature to track a reference signal by manipulating the oil flow, in the possible presence of fast disturbances caused by passing clouds. Although this plant may be successfully controlled by methods assuming it to be modeled as a "black box" lumped parameter system, the point of view advocated in this paper is that explicit consideration of its distributed character leads to an increased control performance. In this respect, the contributions of this paper are twofold: First, a controller relying on variable sampling is developed. This is derived from the partial differential equation describing the oil temperature evolution in time and space on the field and has the effect of linearizing the plant model. Second, the resulting performance is illustrated by means of experiments performed in an actual solar field. The experiments reported show that it is possible to make fast temperature setpoint changes, with reduced overshoot. The ideas presented are applicable to other types of industrial processes, involving transport phenomena.

16 January 2021 in Remote Sensing
Verified
Journal Article
Open access
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KRKashyap Raiyani
Kashyap Raiyani
Teresa GonçalvesTeresa Gonçalves
Teresa Gonçalves
Luis RatoLuis Rato
Luis Rato
PSPedro Salgueiro
Pedro Salgueiro
JSJosé Marques Da Silva
José Marques Da Silva
Given the continuous increase in the global population, the food manufacturers are advocated to either intensify the use of cropland or expand the farmland, making land cover and land usage dynamics mapping vital in the area of remote sensing. In this regard, identifying and classifying a high-resolution satellite imagery scene is a prime challenge. Several approaches have been proposed either by using static rule-based thresholds (with limitation of diversity) or neural network (with data-dependent limitations). This paper adopts the inductive approach to learning from surface reflectances. A manually labeled Sentinel-2 dataset was used to build a Machine Learning (ML) model for scene classification, distinguishing six classes (Water, Shadow, Cirrus, Cloud, Snow, and Other). This models was accessed and further compared to the European Space Agency (ESA) Sen2Cor package. The proposed ML model presents a Micro-F1 value of 0.84, a considerable improvement when compared to the Sen2Cor corresponding performance of 0.59. Focusing on the problem of optical satellite image scene classification, the main research contributions of this paper are: (a) an extended manually labeled Sentinel-2 database adding surface reflectance values to an existing dataset; (b) an ensemble-based and a Neural-Network-based ML models; (c) an evaluation of model sensitivity, biasness, and diverse ability in classifying multiple classes over different geographic Sentinel-2 imagery, and finally, (d) the benchmarking of the ML approach against the Sen2Cor package.

1 December 2003 in Control Engineering Practice
Verified
Journal Article
Closed access
RNRui Neves-Silva
Rui Neves-Silva
Luis RatoLuis Rato
Luis Rato
JLJoao M Lemos
Joao M Lemos

1 January 1997 in Journal of Process Control
Verified
Journal Article
Closed access
SISilva
Silva
Luis RatoLuis Rato
Luis Rato
JLJoao M Lemos
Joao M Lemos
FCF. Coito
F. Coito

1 January 2009 in Networks and Heterogeneous Media
Verified
Journal Article
Open access
PDF file
JLJoao M Lemos
Joao M Lemos
FMFernando Machado
Fernando Machado
NNNuno Nogueira
Nuno Nogueira
Luis RatoLuis Rato
Luis Rato
MRManuel Rijo
Manuel Rijo
RIR. Alves Redol 9 Inesc-Id
R. Alves Redol 9 Inesc-Id
The performance achieved with both adaptive and non-adaptive Model Predictive Control (MPC) when applied to a pilot irrigation channel is evaluated. Several control structures are considered, corresponding to various degrees of centralization of sensor information, ranging from local upstream control of the different channel pools to multivariable control using only proximal pools, and centralized multivariable control relying on a global channel model. In addition to the non-adaptive version, an adaptive MPC algorithm based on redundantly estimated multiple models is considered and tested with and without feedforward of adjacent pool levels, both for upstream and downstream control. In order to establish a baseline, the results of upstream and local PID controllers are included for comparison. A systematic simulation study of the performances of these controllers, both for disturbance rejection and reference tracking is shown.