Oscar Sanchez

Dr. Oscar Sanchez


Research Focus & Metrics

Academic Career Length

6Years (2021-Present)

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

Representative Publications

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16 February 2023 in IEEE Access
Verified
Journal Article
Open access
OSOscar Sanchez
Oscar Sanchez
GMGabriel Martinez-Soltero
Gabriel Martinez-Soltero
JAJesus G. Alvarez
Jesus G. Alvarez
Alma Y. AlanisAlma Y. Alanis
Alma Y. Alanis
Induction motors can be modeled in different ways for correct operation and control, one of these is the α - β representation, this model has six state variables that can be monitored: rotor position, rotor speed, α flux, β flux, α current and β current. Usually, only three of these variables can be measured directly with sensors. These sensors are subject to long periods of work and stress, so a failure in these sensors cannot be ruled out. Sensor failure can cause problems to control the motor, instability or motor performance degradation. That is why fault tolerant controllers are proposed to maintain the stability of the induction motor despite sensor failure, assuming that the error is classified correctly and in a short period of time. This paper is concerned with the detection and classification of sensor faults: rotor position, α and β currents, in real time, considered faults can occur by sensor disconnection, sensor degradation, sensor failure, or connection damage, among other hardware or software phenomena. Different neural networks are proposed and compared for real-time classification, these are: Multilayer perceptron, convolutional neural network, the unidirectional Long short-term memory (LSTM) and bidirectional LSTM. The results show that the CNN neural network presents the best performance compared to the other methods, but the LSTM has a shorter classification time with high accuracy to classify the true class. The CNN used corresponds to a simple configuration of a convolution layer with 20 filters of 2×1, followed by a pooling layer and two dense layers. The results show that CNN has a classification accuracy above 99% and an average classification time per sample of 4.6236e-08 s. For its part, the LSTM shows a classification accuracy of approximately 99% and an average classification time per sample of 3.1298e-09 s, MLP shows a classification accuracy of 97.96% with a classification time of 5.5 e-10 s, while BiLSTM shows an accuracy above of 98% and a classification time of 4.47e-4 s.

11 May 2021 in Mathematics
Verified
Journal Article
Open access
PDF file
Alma Y. AlanisAlma Y. Alanis
Alma Y. Alanis
OSOscar Sanchez
Oscar Sanchez
JAJesus G. Alvarez
Jesus G. Alvarez
Wind energy is one of the most promising alternatives as energy sources; however, to obtain the best results, producers need to forecast the wind speed, generated power and energy price in order to provide the appropriate tools for optimal operation, planning, control and marketing both for isolated wind systems and for those that are interconnected to a main distribution network. For the present work, a novel methodology is proposed for the forecasting of time series in wind energy systems; it consists of a high-order neural network that is trained on-line by the extended Kalman filter algorithm. Unlike most modern artificial intelligence methods of forecasting, which are based on hybridizations, data pre-filtering or deep learning methods, the proposed method is based on the simplicity of implementation, low computational complexity and real-time operation to produce 15-step-ahead forecasting in a time series of wind speed, generated power and energy price. The proposed scheme has been evaluated using real data from open access repositories of wind farms. The results show that an on-line training of the neural network produces high precision, without the need for any other information beyond a few past observations.

25 September 2023 in Mathematics
Verified
Journal Article
Open access
PDF file
Alma Y. AlanisAlma Y. Alanis
Alma Y. Alanis
OSOscar Sanchez
Oscar Sanchez
AVAlonso Vaca-González
Alonso Vaca-González
EREduardo Rangel
Eduardo Rangel
Time series classification is a challenging and exciting problem in data mining. Some diseases are classified and diagnosed based on time series. Such is the case for diabetes mellitus, which can be analyzed based on data from the oral glucose tolerance test (OGTT). Prompt diagnosis of diabetes mellitus is essential for disease management. Diabetes mellitus does not appear suddenly; instead, the patient presents symptoms of impaired glucose tolerance that can also be diagnosed via glucose tolerance testing. This work presents a classification and diagnosis scheme for diseases, specifically diabetes mellitus and poor glucose tolerance, using deep neural networks based on time series data. In addition, data from virtual patients were obtained through the Dalla Man and UVA/Padova models; the validation was carried out with data from actual patients. The results show that deep neural networks have an accuracy of 96%. This indicates that DNNs is a helpful tool that can improve the diagnosis and classification of diseases in early detection.

10 December 2022 in Machines
Verified
Journal Article
Open access
PDF file
OSOscar Sanchez
Oscar Sanchez
Erasmo Gabriel Martinez SolteroErasmo Gabriel Martinez Soltero
Erasmo Gabriel Martinez Soltero
JAJesus G. Alvarez
Jesus G. Alvarez
Alma Y. AlanisAlma Y. Alanis
Alma Y. Alanis
The main steps involved in a fault-tolerant control (FTC) scheme are the detection of failures, isolation and reconfiguration of control. Fault detection and isolation (FDI) is a topic of interest due to its importance for the controller, since it provides the necessary information to adjust and mitigate the effects of the fault. Generally, the most common failures occur in the actuator or in sensors, so this article proposes a novel model-free scheme for the detection and isolation of sensor and actuator faults of induction motors (IM). The proposed methodology performs the task of detecting and isolating faults over data streams just after the occurrence of the failure of an induction motor (IM), by the occurrence of either disconnection, degradation, failure, or connection damage. Our approach proposes deep neural networks that do not need a nominal model or generate residuals for fault detection, which makes it a useful tool. In addition, the fault-isolation approach is carried out by classifiers that differentiate characteristics independently of the other classifiers. The long short-term memory (LSTM) neural network, bidirectional LSTM, multilayer perceptron and convolutional neural network are used for this task. The proposed sensors’ and actuator’s fault detection and isolation scheme is simple. It can be applied to various problems involving fault detection and isolation schemes. The results show that deep neural networks are a powerful and versatile tool for fault detection and isolation over data streams.

1 October 2021 in Mathematics
Verified
Journal Article
Open access
PDF file
Alma Y. AlanisAlma Y. Alanis
Alma Y. Alanis
DRDaniel Ríos-Rivera
Daniel Ríos-Rivera
ESEdgar N. Sanchez
Edgar N. Sanchez
OSOscar Sanchez
Oscar Sanchez
In this paper, we present an impulsive pinning control algorithm for discrete-time complex networks with different node dynamics, using a linear algebra approach and a neural network as an identifier, to synthesize a learning control law. The model of the complex network used in the analysis has unknown node self-dynamics, linear connections between nodes, where the impulsive dynamics add feedback control input only to the pinned nodes. The proposed controller consists of the linearization for the node dynamics and a reorder of the resulting quadratic Lyapunov function using the Rayleigh quotient. The learning part of the control is done with a discrete-time recurrent high order neural network used for identification of the pinned nodes, which is trained using an extended Kalman filter algorithm. A numerical simulation is included in order to illustrate the behavior of the system under the developed controller. For this simulation, a 20-node complex network with 5 different node dynamics is used. The node dynamics consists of discretized versions of well-known continuous chaotic attractors.

28 November 2023 in Axioms
Verified
Journal Article
Open access
PDF file
Alma Y. AlanisAlma Y. Alanis
Alma Y. Alanis
JBJose de Jesus Hernandez Barragan
Jose de Jesus Hernandez Barragan
DRDaniel Ríos-Rivera
Daniel Ríos-Rivera
OSOscar Sanchez
Oscar Sanchez
Erasmo Gabriel Martinez SolteroErasmo Gabriel Martinez Soltero
Erasmo Gabriel Martinez Soltero
In complex dynamical networks, pinning control techniques are often applied to control a small fraction of the nodes in order to stabilize the network with reduced control effort and energy, facilitating adequate development of the complex network. Selecting the controlled nodes is a key challenge to achieving optimal performance. Theoretical analysis of the network provides the minimum quantity of nodes to control but does not specify which ones should be controlled. Analytically, controllability analysis of the entire network would be ideal, but this becomes difficult for complex networks with a large number of nodes and non-linear dynamics. Another option is to evaluate all possible combinations with the minimum number of necessary nodes or the nodes that can be controlled, but this presents a computational challenge due to the large number of possible combinations. Therefore, the remaining option is the use of metaheuristic algorithms for the rapid and practical evaluation of these combinations. In this work, we propose to optimize the selection of nodes for pinning control based on binary optimization algorithms, subject to control and development constraints. The proposed approach involves finding a binary combination with a fixed number of controlled nodes that best stabilizes the network state to zero. This paper includes a comparative study among state-of-the-art binary optimization algorithms and modified classic optimization algorithms. The applicability of the proposed approach is validated through simulations considering a dynamical discrete-time complex network.