Carlos Hernández-Mejía | Universidad Veracruzana (original) (raw)

Papers by Carlos Hernández-Mejía

Multimodal technologies and interaction, Jul 10, 2024

Technologies, Jun 3, 2024

Technologies (Basel), Dec 4, 2023

Multimedia Tools and Applications, Apr 7, 2022

This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY

Iranian Journal of Science and Technology-Transactions of Electrical Engineering, Sep 12, 2022

Multimedia Tools and Applications, Mar 28, 2022

Circuits Systems and Signal Processing, Oct 10, 2017

The memristor and the memristive systems have represented a challenge to be incorporated into a s... more The memristor and the memristive systems have represented a challenge to be incorporated into a simulation procedure in order to carry out novel applications. The discovery of the physical memristor by the HP Labs has caused widespread interest for modeling the memristive behavior in order to combine this new fundamental circuit element with traditional devices. DC domain analysis represents a fundamental stage in the circuit simulators because the DC operating points are used as starting points in other analysis domains. In this work, the DC response of mathematical memristive systems is explored in order to recognize different scenarios according to the nature of the memristive variable. The piecewise linear formulation has been used in order to establish the memristive phenomenon in the device. As a result of this exploration, a novel DC modeling methodology for memristive systems is introduced. This methodology is capable of generating current-voltage branch relationships that represent the memristive behavior of the device. The memristive model proposed is characterized in order to determinate the impact of the variables on the memristive behavior. Moreover, the existence of multiple DC operation points (MOPs) is treated and the conditions for the occurrence of MOPs are established by two cases of study.

Circuits Systems and Signal Processing, Jun 8, 2016

The physical conception of the memristor by the Hewlett-Packard Labs has opened the possibility o... more The physical conception of the memristor by the Hewlett-Packard Labs has opened the possibility of combining this new fundamental circuit element with traditional devices in order to carried out novel applications. An important step for incorporating the memristor into the computer-aided design tools is to find an expression that represents the behavior of the device. In this paper, a novel modeling methodology for memristive systems using homotopy perturbation methods is introduced. This methodology is capable of generating a semi-symbolical expression that represents the memristive behavior of the device. The new memristor model is characterized in order to determinate the impact of the variables on the memristive behavior and establishes the range of compliance using the principal fingerprints of the memristor. Besides, the novel memristor model is depicted by two cases of study. Finally, the advantages of the memristor model are presented and discussed.

Path planning has been considered an import part of solving problems focused on collision-free mo... more Path planning has been considered an import part of solving problems focused on collision-free movements for robotics system. Resistive Grid Path Planning Methodology (RGPPM) is a novel and reduced CPU time modelling procedure for robotic motions planning. In this paper, RGPPM is complements with a monocular vision system to generate autonomy in the planning of the paths with geometric resistive networks.

Multimedia Tools and Applications, Jun 26, 2020

Exploring the conception of robust encryption techniques for the security of digital images is a ... more Exploring the conception of robust encryption techniques for the security of digital images is a permanent necessity due to the existence of the Internet where sending and receiving information to establish communication is a high priority activity. Encryption process is carried out by data transformation, i.e. shuffled or scrambled, so that the information can not be read by an unauthorized receiver and it can exclusively be decrypted using valid-keys. In this paper, a novel fusion-scheme based on mathematical equation system for encryptionimage algorithm is explored. In order to do that, numerical pixels are introduced in a system of equations for fusing images with three different private-keys. In addition, classical tests between original and encrypted images such as correlation coefficient, number of changing pixel rate (NPCR), unified average changed intensity (UACI) and entropy have been carried out to support the effectiveness of image fusion for image encryption.

Memristor and memristive circuits exhibit a hysteresis v-i characteristic, which is strongly depe... more Memristor and memristive circuits exhibit a hysteresis v-i characteristic, which is strongly dependent on the state variable function. In this way, controlling the state variable performance can give a more realistic description of the device. This work presents the use of a PWL window function to establish the behavior of the state variable function with the purpose of analyzing the influence of the novel window function in the characteristic curves of the memristive systems, such as: the pinched hysteresis loop and the memristance. The notion of asymmetrical window functions is introduced in order to catch sight of the advantages of the PWL window functions compared to the typical window functions. Moreover, a simple comparison regarding several window functions is achieved.

Logistics, Aug 15, 2022

Path planning has been considered as key part for expanding the intelligent properties because it... more Path planning has been considered as key part for expanding the intelligent properties because it faces the problem of finding collision-free motions for robot systems from one configuration to another. Resistive Grid Path Planning Methodology (RGPPM) is a novel and reduced CPU time modelling and simulation procedure for robotic motions planning. In this paper, robotical implementations of collision-free path planning using an emerging grid-based methodology is carried out by embedded systems applications and robot application framework.

Robotica, Aug 22, 2019

SUMMARYPath planning represents planning collision-free strategies to move from starting point to... more SUMMARYPath planning represents planning collision-free strategies to move from starting point to ending point. These strategies can be carried out for known and unknown environments. Recently, a novel and reduced CPU-time modeling and simulation methodology for path planning in known environment based on resistive grids (RGs) has been introduced. In this work, a novel modified version of Resistive Grid Path Planning Methodology (RGPPM) methodology is presented with the purpose of exploring collision-free path planning for robotic arms. This extension of the methodology allows to numerically relate positions in the RG with angular values of the robotic systems. In addition, it is possible to include obstacles in the configuration space, and therefore collision detection can be established for RGs. Finally, the variation of links for robotic arms and obstacles for configuration space is explored by simulating different scenarios.

Arabian journal for science and engineering, Aug 9, 2018

In mobile robotics area, path planning has been considered as key part for expanding the intellig... more In mobile robotics area, path planning has been considered as key part for expanding the intelligent properties because it faces the problem of finding collision-free motions for robot systems from one configuration to another. This problem deals with the challenge of searching trajectories that optimize some cost function as the minimum cumulative edge cost, i.e., the shortest path. In addition, it is necessary that path planning can be carried out with reduced CPU time in order to tackle more complex environments in real time. In this work, the analysis of different resistive grid (RG) configurations in order to achieve the shortest path is presented. Additionally, the use of an alternative technique to decrease computing time is introduced. As a result of this research, a modeling and simulation methodology is presented. This methodology is capable of modeling the environment, formulating the equilibrium equations, solving the system of equations and finding the path between the starting and ending points. The configuration space has been modeled with square, square with diagonals, square with center, hexagonal and hexagonal with center RGs. Besides, the formulation of the equilibrium equation has been established using modified nodal analysis. Furthermore, the solution of the system of equations has been carried out using multifrontal method. In addition, the local current comparison algorithm has been resorted in order to find the shortest path. Moreover, the impact of incorporating obstacles into the configuration space of the RGs is explored. As part of the exploration to reduce CPU times, the novel methodology has been expanded into high-level programming language, i.e., Python. Finally, new contributions of this work are expounded and discussed.

Technologies (Basel), Jan 10, 2022

In Mexico, the incorporation of deaf people into education has been lacking since only 14% of the... more In Mexico, the incorporation of deaf people into education has been lacking since only 14% of the deaf population in the age group between 3 and 29 years access education with the support of a hearing aid. Additionally, those who have been incorporated frequently face inappropriate educational strategies which poorly develop the use of Mexican Sign Language (MSL) and therefore academical success and opportunities for insertion in the workplace are difficult. This research explores a novel mexican sign language lexicon video dataset containing the dynamical gestures most frequently used by MSL. Each gesture consists of a set of different versions of videos under uncontrolled conditions. MX-ITESO-100 data set is composed of a lexicon of 100 gestures and 5,000 videos from three participants with different grammatical elements. Additionally, the data set is evaluated in a two-step neural network model with an accuracy greater than 99%. and thus serves as a benchmark for future training ...