David Velásquez

Prof. David Velásquez

Universidad EAFIT
+1
orcid

Research Focus & Metrics

Academic Career Length

12Years (2015-Present)

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

Representative Publications

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4 July 2022 in IEEE Access
Verified
Journal Article
Open access
David VelásquezDavid Velásquez
David Velásquez
EPEnrique Perez
Enrique Perez
XOXabier Oregui
Xabier Oregui
AAArkaitz Artetxe
Arkaitz Artetxe
JMJorge Manteca
Jorge Manteca
BSBasilio Sierra
Basilio Sierra
Detecting faults and anomalies in real-time industrial systems is a challenge due to the difficulty of sufficiently covering an industrial system’s complexity. Today, Industry 4.0 makes it possible to tackle these problems through emerging technologies such as the Internet of Things and Machine Learning. This paper proposes a hybrid machine-learning ensemble real-time anomaly-detection pipeline that combines three Machine Learning models–Local Outlier Factor, One-Class Support Vector Machine, and Autoencoder–, through a weighted average to improve anomaly detection. The ensemble model was tested with three air-blowing machines obtaining a ${F}_{{1}}$ -score value of 0.904, 0.890, and 0.887, respectively. The results of the ensemble model showed improved performance metrics concerning the individual metrics. A novelty of this model is that it consists of two stages inspired by a standard industrial system: i) a manufacturing stage and ii) an operation stage.

19 January 2020 in Applied Sciences
Verified
Journal Article
Open access
PDF file
David VelásquezDavid Velásquez
David Velásquez
ASAlejandro Sánchez
Alejandro Sánchez
SSSebastian Sarmiento
Sebastian Sarmiento
Mauricio ToroMauricio Toro
Mauricio Toro
MMMikel Maiza
Mikel Maiza
BSBasilio Sierra
Basilio Sierra
Agricultural activity has always been threatened by the presence of pests and diseases that prevent the proper development of crops and negatively affect the economy of farmers. One of these pests is Coffee Leaf Rust (CLR), which is a fungal epidemic disease that affects coffee trees and causes massive defoliation. As an example, this disease has been affecting coffee trees in Colombia (the third largest producer of coffee worldwide) since the 1980s, leading to devastating losses between 70% and 80% of the harvest. Failure to detect pathogens at an early stage can result in infestations that cause massive destruction of plantations and significantly damage the commercial value of the products. The most common way to detect this disease is by walking through the crop and performing a human visual inspection. As a result of this problem, different research studies have proven that technological methods can help to identify these pathogens. Our contribution is an experiment that includes a CLR development stage diagnostic model in the Coffea arabica, Caturra variety, scale crop through the technological integration of remote sensing (through drone capable multispectral cameras), wireless sensor networks (multisensor approach), and Deep Learning (DL) techniques. Our diagnostic model achieved an F1-score of 0.775. The analysis of the results revealed a p-value of 0.231, which indicated that the difference between the disease diagnosis made employing a visual inspection and through the proposed technological integration was not statistically significant. The above shows that both methods were significantly similar to diagnose the disease.

10 May 2025 in Agriculture
Verified
Journal Article
Open access
PDF file
Joan Francisco Alvarado MolinaJoan Francisco Alvarado Molina
Joan Francisco Alvarado Molina
JRJuan Felipe Restrepo-Arias
Juan Felipe Restrepo-Arias
David VelásquezDavid Velásquez
David Velásquez
MMMikel Maiza
Mikel Maiza
Computer vision in the agriculture field aims to find solutions to guarantee and assure farmers the quality of their products. Therefore, studies to diagnose diseases and detect anomalies in crops, through computer vision, have been growing in recent years. However, crops such as cocoa required further attention to drive advances in computer vision to the detection of diseases. As a result, this paper aims to explore the computer vision methods used to diagnose diseases in crops, especially in cocoa. Therefore, the purpose of this paper is to provide answers to the following research questions: (Q1) What are the diseases affecting cocoa crop production? (Q2) What are the main Machine Learning algorithms and techniques used to detect and classify diseases in cocoa? (Q3) What are the types of imaging technologies (e.g., RGB, hyperspectral, or multispectral cameras) commonly used in these applications? (Q4) What are the main Machine Learning algorithms used in mobile applications and other platforms for cocoa disease detection? This paper carries out a Systematic Literature Review approach. The Scopus Digital, Science Direct Digital, Springer Link, and IEEE Explore databases were explored from January 2019 to August 2024. These questions have identified the main diseases that affect cocoa crops and their production. From this, it was identified that mostly Machine Learning algorithms based on computer vision are employed to detect anomalies in cocoa. In addition, the main sensors were explored, such as RGB and hyperspectral cameras, used for the creation of datasets and as a tool to diagnose or detect diseases. Finally, this paper allowed us to explore a Machine Learning algorithm to detect disease deployed in mobile and Internet of Things applications for detecting diseases in cocoa crops.

30 September 2018 in Computación y Sistemas
Verified
Journal Article
Closed access
PDF file
EMElizabeth Suescún Monsalve
Elizabeth Suescún Monsalve
JLJulio Cesar Camapio Do Prado Leite
Julio Cesar Camapio Do Prado Leite
VWVera Werneck
Vera Werneck
RMRaul Mazo
Raul Mazo
PVPaola Vallejo
Paola Vallejo
RRRafael Rincón
Rafael Rincón
SimulES-W: A Collaborative Game to Improve Software Engineering Teaching

13 August 2021 in Sensors
Verified
Journal Article
Open access
PDF file
David VelásquezDavid Velásquez
David Velásquez
ASAlejandro Sánchez
Alejandro Sánchez
SSSebastián Sarmiento
Sebastián Sarmiento
CVCamilo Velásquez
Camilo Velásquez
Mauricio ToroMauricio Toro
Mauricio Toro
BSBasilio Sierra
Basilio Sierra
Coffee Leaf Rust (CLR) is a fungal epidemic disease that has been affecting coffee trees around the world since the 1980s. The early diagnosis of CLR would contribute strategically to minimize the impact on the crops and, therefore, protect the farmers’ profitability. In this research, a cyber-physical data-collection system was developed, by integrating Remote Sensing and Wireless Sensor Networks, to gather data, during the development of the CLR, on a test bench coffee-crop. The system is capable of automatically collecting, structuring, and locally and remotely storing reliable multi-type data from different field sensors, Red-Green-Blue (RGB) and multi-spectral cameras (RE and RGN). In addition, a data-visualization dashboard was implemented to monitor the data-collection routines in real-time. The operation of the data collection system allowed to create a three-month size dataset that can be used to train CLR diagnosis machine learning models. This result validates that the designed system can collect, store, and transfer reliable data of a test bench coffee-crop towards CLR diagnosis.

19 December 2022 in IEEE Computer Graphics and Applications
Verified
Journal Article
Open access
IOIgor G. Olaizola
Igor G. Olaizola
Jan Lukas BruseJan Lukas Bruse
Jan Lukas Bruse
JOJuan Odriozola
Juan Odriozola
AAArkaitz Artetxe
Arkaitz Artetxe
David VelásquezDavid Velásquez
David Velásquez
Jorge PosadaJorge Posada
Jorge Posada
The Covid-19 pandemic and its dramatic worldwide impact have required global multidisciplinary actions to mitigate its effects. Mobile phone activity-based digital contact tracing (DCT) via Bluetooth Low Energy (BLE) technology has been considered a powerful pandemic monitoring tool, yet it sparked a controversial debate about privacy risks for people. In order to explore the potential benefits of a DCT system in the context of Occupational Risk Prevention, this paper presents the potential of Visual Analytics methods to summarize and extract relevant information from complex DCT data collected during a long-term experiment at our research centre. Visual tools were combined with quantitative metrics to provide insights into contact patterns among volunteers. Results showed that crucial actors such as participants acting as bridges between groups could be easily identified - ultimately allowing for making more informed management decisions aimed at containing the potential spread of a disease.