Rafael V. Carvalho

Dr. Rafael V. Carvalho

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Research Focus & Metrics

Academic Career Length

18Years (2009-Present)

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

Representative Publications

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9 December 2012 in Computational and Mathematical Methods in Medicine
Verified
Journal Article
Open access
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RCRafael V. Carvalho
Rafael V. Carvalho
JKJetty Kleijn
Jetty Kleijn
Annemarie MeijerAnnemarie Meijer
Annemarie Meijer
FVFons Verbeek
Fons Verbeek
In the study of complex patterns in biology, mathematical and computational models are emerging as important tools. In addition to experimental approaches, these modeling tools have recently been applied to address open questions regarding host-pathogen interaction dynamics, including the immune response to mycobacterial infection and tuberculous granuloma formation. We present an approach in which a computational model represents the interaction of theMycobacteriuminfection with the innate immune system in zebrafish at a high level of abstraction. We use the Petri Net formalism to model the interaction between the key host elements involved in granuloma formation and infection dissemination. We define a qualitative model for the understanding and description of causal relations in this dynamic process. Complex processes involving cell-cell or cell-bacteria communication can be modeled at smaller scales and incorporated hierarchically into this main model; these are to be included in later elaborations. With the infection mechanism being defined on a higher level, lower-level processes influencing the host-pathogen interaction can be identified, modeled, and tested both quantitatively and qualitatively. This systems biology framework incorporates modeling to generate and test hypotheses, to perform virtual experiments, and to make experimentally verifiable predictions. Thereby it supports the unraveling of the mechanisms of tuberculosis infection.

17 November 2021 in Energies
Verified
Journal Article
Open access
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DSDiogo F. Costa Silva
Diogo F. Costa Silva
AFArlindo Rodrigues Galvão Filho
Arlindo Rodrigues Galvão Filho
RCRafael V. Carvalho
Rafael V. Carvalho
FRFilipe de Souza L. Ribeiro
Filipe de Souza L. Ribeiro
CCClarimar Coelho
Clarimar Coelho
Water flow forecasts are an essential information for energy production, management and hydropower control. Advanced actions to optimize electricity production can be taken based on predicted information. This work proposes an ensemble strategy using recurrent neural networks to generate a forecast of water flow at Jirau Hydroelectric Power Plant (HPP), installed on the Madeira River in Brazil. The ensemble strategy consists of combining three long short-term memory (LSTM) networks that model the Madeira River and two of its tributaries: Mamoré and Abunã rivers. The historical data from streamflow of the Madeira river and its tributaries are used to validate the ensemble LSTM model, where each time series of river tributaries are modeled separated by LSTM models and the result used as input for another LSTM model in order to forecast the streamflow of the main river. The experimental results present low errors for training and test sets for individual LSTM networks and ensemble model. In addition, these results were compared with the operational forecasts performed by Jirau HPP. The proposed model showed better accuracy in four of the five scenarios tested, which indicates a promising approach to be explored in water flow forecasting based on river tributaries.

1 June 2020
Verified
Conference Paper
Closed access
AFArlindo Rodrigues Galvão Filho
Arlindo Rodrigues Galvão Filho
DSDiogo Fernandes Costa Silva
Diogo Fernandes Costa Silva
RCRafael V. Carvalho
Rafael V. Carvalho
FRFilipe de Souza Lima Ribeiro
Filipe de Souza Lima Ribeiro
CCClarimar Coelho
Clarimar Coelho
The water flow is an important information for the study of the energy production as well as management and hydropower control. The forecast of future information scenarios allows to take advanced actions in order to optimize electricity generation. This work proposes a model to generate a forecast of water flow based on a Recurrent Neural Network, more specifically the long short-term memory (LSTM) type. The dataset used to validate the LSTM model is obtained from flow history of Jirau Hydroelectric Power Plant, installed on the Madeira River in the state of Rondônia, Brazil. The model was trained and tested on one-day time-step resolution. Experimental results shows a lower error according its predictive capacity. The resulted forecast was evaluated by operating staff ex-perts, from Jirau Hydroelectric Power Plant, which attested the results can be used in real operation scenario. It is concluded that LSTM model is a good strategy for the forecast of water flow for the study of hydroelectric turbine efficiency.

18 December 2020 in Energies
Verified
Journal Article
Open access
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GFGabriela Rocha de Oliveira Fleury
Gabriela Rocha de Oliveira Fleury
DNDouglas Vieira Do Nascimento
Douglas Vieira Do Nascimento
AFArlindo Rodrigues Galvão Filho
Arlindo Rodrigues Galvão Filho
FRFilipe de Souza Lima Ribeiro
Filipe de Souza Lima Ribeiro
RCRafael V. Carvalho
Rafael V. Carvalho
CCClarimar Coelho
Clarimar Coelho
Monitoring and management of water levels has become an essential task in obtaining hydroelectric power. Activities such as water resources planning, supply basin management and flood forecasting are mediated and defined through its monitoring. Measurements, performed by sensors installed on the river facilities, are used for precisely information about water level estimations. Since weather conditions influence the results obtained by these sensors, it is necessary to have redundant approaches in order to maintain the high accuracy of the measured values. Staff gauge monitored by conventional cameras is a common redundancy method to keep track of the measurements. However, this method has low accuracy and is not reliable once it is monitored by human eyes. This work proposes to automate this process by using image processing methods of the staff gauge to measure and deep neural network to estimate the water level. To that end, three models of neural networks were compared: the residual networks (ResNet50), a MobileNetV2 and a proposed model of convolutional neural network (CNN). The results showed that ResNet50 and MobileNetV2 present inferior results compared to the proposed CNN.

8 April 2015 in Computation
Verified
Journal Article
Open access
PDF file
RCRafael V. Carvalho
Rafael V. Carvalho
JHJeroen Van Den Heuvel
Jeroen Van Den Heuvel
JKJetty Kleijn
Jetty Kleijn
FVFons Verbeek
Fons Verbeek
Computational and mathematical modeling is important in support of a better understanding of complex behavior in biology. For the investigation of biological systems, researchers have used computers to construct, verify, and validate models that describe the mechanisms behind biological processes in multi-scale representations. In this paper we combine Petri net models that represent the mycobacterial infection process and innate immune response at various levels of organization, from molecular interaction to granuloma dissemination. In addition to the conventional graphical representation of the Petri net, the outcome of the model is projected onto a 3D model representing the zebrafish embryo. In this manner we provide a visualization of the process in a simulation framework that portrays the infection in the living system.

5 March 2020 in Fronteiras: Journal of Social, Technological and Environmental Science
Verified
Journal Article
Open access
GCGuilherme Coelho
Guilherme Coelho
AFArlindo Rodrigues Galvão Filho
Arlindo Rodrigues Galvão Filho
RCRafael V. Carvalho
Rafael V. Carvalho
GTGustavo Teodoro-Laureano
Gustavo Teodoro-Laureano
SASamyra Almeida-Da-Silveira
Samyra Almeida-Da-Silveira
CCClarimar José Coelho
Clarimar José Coelho
The determination of infection rate parameter from in vitro macrophages infected by Leishmania amastigotes is fundamental in the study of vaccine candidates and new drugs for the treatment of leishmaniasis. The conventional method that consists in the amastigotes count inside macrophages, normally is done by a trained microscope technician, which is liable to misinterpretation and sampling. The objective of this work is to develop a method for the segmentation of images to enable the automatic calculation of the infection rate by amastigotes. Segmentation is based on mathematical morphology in the context of a computer vision system. The results obtained by computer vision system presents a 95% accuracy in comparison to the conventional method. Therefore, the proposed method can contribute to the speed and accuracy of analysis of infection rate, minimizing errors from the traditional methods, especially in situations where exhaustive repetitions of the procedure are required from the technician.