INTEGRATION AND INFORMATION RETRIEVAL BY MULTIPLEXING VISIBLE TETRACHROMATIC QR CODES EMBEDDED IN PRINTED IMAGES

01/07/2025

Two-dimensional quick response (QR) codes were created to transmit information in a simple and versatile way, facilitating, for example, to aid in the exchange of information about a product. This motivated the development of this work, which presents an innovative methodology to improve the security of information in printed QR codes by integrating two levels of protection. Two-dimensional QR codes are widely used to transmit information, including sensitive data in documents such as passports and financial reports. Therefore, it is crucial to implement robust security mechanisms. The proposal consists of first encrypting the information using the Privacy Guard (GPG) method and then multiplexing two sets of data into a chromatic QR code, where different colors represent different encoded information. This double layer of security provides greater protection against unauthorized access to information. The results demonstrate that multiplexing dichromatic QR data into a tetrachromatic code is feasible and improves both storage capacity and data security. Furthermore, the use of the YCbCr color model enables accurate retrieval of the original codes, even in the presence of brightness variations. The developed method provides an advanced solution for data protection in printed documents, with potential applications in various fields where high information security is required. Key Words: Binary ratio, chrominance, color, demultiplexing, dichromatic, encryption, identification, luminance, multiplexing, pixel, QR codes, security

SUBSIDENCES ASSOCIATED WITH MINING ENVIRONMENTS AND UNDERGROUND WORKS. CASE OF THE COLLAPSE WITHIN THE LORD DERBY CONCESSION (LINARES-LA CAROLINA MINING DISTRICT)

01/07/2025

In February 2023, a subsidence phenomenon was superficially evident in the “Lord Derby” concession, within the Linares-La Carolina mining district. This exuberant, cone-shaped subsidence reached approximately 30 meters in diameter on the surface and a depth greater than that measurement, being enhanced by the local geological and hydrogeological conditions, as well as by the historical mining activity in the area. The mining work, developed for centuries, together with the recent constructions intended to make the “La Tortilla” mine accessible to visitors, have influenced the instability of the terrain. This case is representative of a phenomenon that can be repeated in similar environments, where intensive mining or the execution of large-scale underground works have modified the subsoil. In order to assess the susceptibility of other areas to this type of subsidence, a methodology is proposed based on defining the risks of subsidence in mining environments and significant underground works, establishing the conditions that determine the collapse of the “La Tortilla” mine (geology, hydrogeology, exploitation of the aquifer, mining work and perimeter fencing of the visitable mine) and establishing the sequencing of this collapse. As a result, possible solutions are proposed for the case of the collapse of “La Tortilla”, a 3D model of the “Arrayanes” Mine, located in a nearby area, and with similar conditions to those existing in the collapse area, is proposed as an example to help detect areas at risk of subsidence. This model will allow identifying high-risk areas and anticipating possible collapses. Finally, in cases where subsidence could not be prevented, solutions are proposed for the stabilization of the land and appropriate mitigation measures to minimize future impacts. Keywords: Hydrogeology, mining work, sinking, subsidence, underground works.

CROSS-BORDER ASSESSMENT OF THE BUSINESS ECOSYSTEM SPECIALIZED IN ADDITIVE MANUFACTURING

01/07/2025

In this paper, a prospective investigation is conducted using open sources on organizations benefiting from additive manufacturing in the cross-border region between western Spain and northern Portugal. This work aims to assess business specialization within the framework of this Industry 4.0 technology in two areas affected by depopulation and deindustrialization processes. The adopted methodology includes a systematic search based on predefined criteria, followed by a quantitative analysis based on three stratification factors: company size, business objectives, and geographic location. Additionally, a qualitative and heuristic analysis of open information from key organizations and their relationship with regional socio-economic development is carried out. Keywords: Smart Specialization, Additive Manufacturing, Regional Development, New Materials.

DRIVE CIRCUIT DESIGN FOR AEROSPACE SEMICONDUCTOR LASER BASED ON SiC DEVICE

XIAOQIANG ZHANG - YUNFENG WANG - CHUNHUI WANG - DI LIU — 01/07/2025

Drive circuits, which are the core part of semiconductor lasers, are crucial to the field of aerospace science and technology, such as laser guidance and Light Detection and Ranging. Given the extremely high quantum efficiency of semiconductor lasers, changes in current easily affect the stability of the output power of semiconductor lasers, which is not conducive to their safe use. Given that the output wavelength and power of semiconductor lasers are considerably changed in the case of even minor changes in the drive current, the working characteristics of semiconductor lasers were analyzed in this study, and the drive circuit design requirements of aerospace semiconductor lasers were obtained. Through circuit simulation, a four-phase interleaved parallel buck converter was established as the main power circuit topology of the semiconductor laser, followed by modeling analysis and compensation network design for the converter through the state space averaging method. Then, the drive circuit was controlled through the average current control method combining the all- Silicon Carbide scheme, and the prototype drive circuit was experimentally verified. Results demonstrate that the drive circuit of the aerospace semiconductor laser designed with a four-phase interleaved parallel buck converter can reduce the ripple coefficient of the output current from 0.244 to 0.015, effectively improve the power system stability, and remarkably improve the switching frequency and power density of the semiconductor laser. The proposed algorithm provides evidence for the optimization and performance evaluation of semiconductor laser drivers for aerospace applications. Keywords: Semiconductor laser, drive circuit, Silicon Carbide, four-phase buck, interleaving parallel.

ERGONOMIC DESIGN OF AN INTELLIGENT ROBOTIC WALKER BASED ON USER PERCEPTION AND NEEDS

ISABEL SEGUI VERDU - LARISA DUNAI DUNAI - VALERIY VYATKIN - DINU TURCANU — 01/07/2025

This article presents the development of a robotic walker designed from an ergonomic perspective, focused on the specific needs of users. The design integrates a height-adjustable modular system, a rectangular frame with four wheels to ensure stability and manoeuvrability, and a vertical folding mechanism for easy transport. Key components were optimized, such as ergonomic handles with support and grooves for improved grip, an anatomical seat made of memory materials, a durable fabric backrest, and a sports bag-type basket attached by hooks. The 24 mm front wheels are spring-loaded to reduce vibrations, while the 20 mm motorized rear wheels have a non-slip surface for overcoming obstacles. The design incorporates safety features such as reflective strips, integrated lights, and advanced sensors (pressure, TOF, IMU), enhancing user comfort, functionality and safety. This comprehensive approach represents a significant advance in the ergonomics and functionality of robotic walkers. Key Words: robotic walker, ergonomic design, user-centred design, handgrips, frame, seat, wheels, electronics, sensors

MODELING, SIMULATION, AND CONTROL OF DISSOLVED OXYGEN IN ACTIVATED SLUDGE WASTEWATER TREATMENT VIA PID CONTROLLER: REDUCING ENERGY COSTS

01/07/2025

This research explores the control of Dissolved Oxygen (DO) in Activated Sludge-based Residual Treatment Plants (ASRTP) using a classic Proportional-Integral-Derivative (PID) controller. In addition to DO control, the system monitors Redox Potential (RP) and Turbidity, ensuring a well-regulated treatment process. The DO levels in the reaction tank are regulated by adjusting the aerators based on the existing Chemical Oxygen Demand (COD) of nutrients and a pre-conducted respirometry analysis. The data indicates that energy consumption can be reduced by up to 66.83%, leading to equivalent financial savings of 73,151.38 dollars, equivalent to 1,406,757.21 kWh per year. The system was tuned to achieve a target DO concentration of 8.0 mg/l within one hour. During this period, the aerators were off for 40.1 minutes and operational for 19.9 minutes. Notably, the aeration system initially operated at 90% of its maximum intensity but subsequently maintained a reduced intensity of 60%, further contributing to energy savings by minimizing both operation time and intensity. Additionally, the DO response was simulated in LabView using the differential equation for DO dynamics in the WWTP, incorporating respirometry parameters like initial oxygen levels, sludge oxygen consumption, and aeration rates. Practical and theoretical responses were compared for validation. PID tuning was done in MATLAB and implemented in LabView, integrating sensors and actuators. Keywords: Wastewater Treatment; Dissolved Oxygen Control; PID control; Mathematical

COMPREHENSIVE EVALUATION METHOD FOR DISTRIBUTION GRIDS BASED ON COMBINATION WEIGHTING AND MODIFIED TOPSIS

ZHEN LU - JIANG QIAN - YONG YAO - XIAOPENG ZHANG — 01/07/2025

Grid planning has become a new and important method. In the process of implementing the grid planning for a distribution network, accurately valuating the performance and advantages of each grid and identifying its weaknesses are prerequisites for a scientific, reasonable, and practical grid planning. Hence, this study introduces an evaluation approach for the construction of a distribution grid to make a pointed investment planning for it. First, an index system of a distribution grid was established. Second, the anti-entropy weight method (a-EWM) and the best-worst method (BWM) were introduced to compute the subjective and objective weights, respectively, and the combination weights were obtained using game theory. Finally, the technique for order preference by similarity to ideal solution (TOPSIS) method was modified using cosine similarity and gray relational analysis (GRA). Results indicate that, (1) The first-level indexes in the evaluation index system here can be used to reflect the overall construction situation of each grid, and the second-level indexes can be employed to represent the weaknesses within each grid. (2) The combination weighting method based on game theory can combine the advantages of subjective and objective weighting methods and reflect the importance of various evaluation indexes accurately. (3) The drawbacks of the traditional TOPSIS method, where index correlation cannot be considered and only relative distance is calculated, resulting in inaccurate evaluation, can be avoided by the modified TOPSIS method, in which cosine similarity and gray relational analysis are adopted. Therefore, the use of combination weighting and the modified TOPSIS method can make the comprehensive evaluation value of a distribution grid more practical. The method here can be utilized to demonstrate the overall status quo and future development demands of distribution grids and compensate for the defects of the traditional evaluation method. Keywords: Distribution grid, Comprehensive evaluation, Combination weighting, TOPSIS.

BENDING FATIGUE CHARACTERISTICS OF A REINFORCED MACADAM BASE

HONGJUN JING - XIANGYU CHEN - YUNLIANG ZHANG - GUOPING ZHANG - BINHUI REN — 01/07/2025

The traditional macadam base structure has poor resistance to road bending deformation. However, reinforcement methods to improve the performance of macadam base structures have not been fully explored. In particular, effective techniques to enhance the bending performance and fatigue life of flexible base structures are still lacking. In this study, geogrids were proposed to reinforce macadam base structures. Comprehensive tests were conducted to evaluate the bending performance and fatigue resistance of reinforced and unreinforced specimens. These tests included bending tensile strength tests, three-point bending fatigue tests, and cyclic loading tests applied at five distinct stress levels. The results show that unreinforced macadam bases have poor bending performance. When the load reaches the 0.8 stress level, the unreinforced specimens experience low-cycle fatigue failure, characterized by a small ultimate displacement and a distinct failure plane. With the inclusion of geogrid reinforcement, the fatigue life of the specimens is significantly improved, with no notable deterioration in the stress-strain yield curves even at high load levels. Reinforced specimens maintain high-cycle fatigue performance at the 0.8 stress level, thereby avoiding low-cycle fatigue failure. Furthermore, the reinforced specimens effectively suppress the propagation of mid-span reflective cracks in the cement-stabilized crushed stone base and delay the extension of diagonal shear cracks near the supports, thereby significantly improving the dynamic stability and long-term durability of the crushed stone base layer in the pavement structures. These findings provide a theoretical reference for the practical application of this reinforcement technology in macadam base structures. Keywords: highway engineering, reinforced macadam base, bending fatigue test, bending fatigue performance; geogrid

ENHANCING INDOOR AIR QUALITY THROUGH NATURAL VENTILATION: INSIGHTS FROM MUNICIPAL BUILDING IN MOSTOLES, SPAIN

01/07/2025

This study evaluates the effectiveness of natural ventilation in enhancing indoor air quality within the Almudena Grandes Central Library, a municipal building in Móstoles, Spain. Triggered by the public health challenges highlighted during the SARS-CoV-2 pandemic, the research develops a methodological framework that integrates CO2 monitoring, occupancy modeling, and airflow calculations to assess air renewal capacities under natural ventilation conditions. The analysis reveals that cross ventilation is the only strategy capable of achieving IDA 2 air quality standards in high-occupancy areas, requiring at least five air changes per hour. Zenithal openings, such as roof ventilators, significantly enhance airflow during colder months with strong indoor-outdoor thermal differentials, even when external wind is minimal—a frequent scenario in continental Spanish climates. The study also explores buoyancy and wind-driven ventilation mechanisms and quantifies their respective contributions using empirical models. Results suggest that the library can maintain acceptable air quality for up to 310 users with sufficient cross-ventilation measures. However, single-sided ventilation proves inadequate. The proposed model supports dynamic capacity management and energy efficiency by integrating real-time environmental data. The authors highlight the potential of automating ventilation systems via domotics for continuous air quality monitoring and optimization. Limitations include the variability of outdoor conditions and the need for future validation using Computational Fluid Dynamics (CFD) and additional case studies. Overall, the findings emphasize architectural strategies as pivotal in promoting healthier, energy-efficient indoor environments in public infrastructure. Key Words: cross ventilation, indoor air quality, natural ventilation, infection risk reduction, occupant load estimation

MATHEMATICAL PROGRAMMING FOR THE SELECTION OF THE IDEAL CYCLE LENGTH IN PREVENTIVE MAINTENANCE POLICIES

JAVIER MAQUIRRIAIN ANTOÑANZAS - ALBERTO GARCIA VILLORIA - RAFAEL PASTOR MORENO — 01/07/2025

The preventive maintenance scheduling problem involves sequencing the inspection of M machines within a cyclic policy of length T periods, where each machine must be inspected at least once. In the case addressed here, and during each period t, the maximum capacity for maintenance tasks is limited to one. The machines to be maintained can generate two types of costs: the maintenance cost, incurred in the periods when the machine is inspected, and the operational cost, which arises in the periods when a machine operates without being inspected. Both costs are directly proportional to the number of periods elapsed since the last maintenance of the machine. For this type of problem, it is common to use cycle lengths predetermined by external factors (such as days in a month or weeks in a year). However, this article introduces a mathematical program that calculates the ideal cycle length T and the optimal maintenance frequencies. The results show that in 69,44% of the instances, an ideal T different from predetermined T value is found. The average execution time is 106,96 seconds. Once the ideal cycle length T is obtained, a matheuristic algorithm is then used to sequence the maintenance tasks for each machine. It is observed that in 65,6% of the instances, the average cost of the maintenance policy is lower than when using predetermined T values, achieving an average cost reduction of 2,41%. Key Words: Mathematical programming, preventive maintenance, matheuristic algorithms, activity sequencing.

CONTAMINANT CHARACTERISTICS OF WASTE FOUNDRY SAND: TOXICITY, MECHANICAL PROPERTIES AND USES

01/07/2025

Residual molding sands from iron casting processes in Tepeapulco, Hidalgo, Mexico—accounting for 65–85% of total foundry waste—were characterized. Mineralogical phases were identified via X-ray diffraction (XRD), while chemical composition was determined using X-ray fluorescence (XRF), inductively coupled plasma (ICP), and atomic absorption spectroscopy (AAS), supported by particle size distribution analysis. Predominant phases included quartz (PDF [96-900-6304]), albite (PDF [96-900-0528]), and orthoclase (PDF [96-900-0312]); minor phases comprised montmorillonite and berlinite. Chemical composition was: 70.1% SiO2, 14.7% Al2O3, 4.4% Fe, 0.20% MnO, 4.30% MgO, 0.40% K2O, 0.6% CaO, 5.26% Na2O, and 0.2% TiO2. Corrosivity testing yielded a pH of 9.38, and reactivity tests showed no reactions with water or air. CN? and S²? ions were below detection limits, and flammability testing confirmed the absence of alcohols, classifying the material as non-toxic and non-flammable. Physical characterization included density, Atterberg limits, thixotropy, stickiness, plasticity, and color. Bricks were fabricated by combining residual sand with clay, vermiculite, and mining waste. The composites exhibited compressive strength of 3.024–16.883?MPa, water absorption of 8.90–18.41%, permeability of (1.64–2.23) × 10?³?cm³/s, and bulk density of 1050–1600?kg/m³. These findings highlight the material’s potential for reuse in construction applications, offering mechanical performance comparable to or exceeding commercial products, with the added benefit of being environmentally safe. Keywords: Residual Sand; Mining Waste; Construction Material; Water Absorption; Permeability; Compressive Strength

DIGITAL TRANSFORMATION AND THE PERFORMANCE OF SPANISH MANUFACTURING FIRMS: THE ROLE OF INDUSTRY TECHNOLOGICAL INTENSITY AND KNOWLEDGE MANAGEMENT

ESTHER GRIJALVO RUPEREZ - MARTA FOSSAS OLALLA - ANTONIO RODRIGUEZ DUARTE — 01/07/2025

This study analyzes digital transformation (DT) in the Spanish manufacturing sector, highlighting its crucial role in business competitiveness within a dynamic and complex environment. Using an econometric model based on panel data (9,215 observations between 2011 and 2017), it examines the impact of three key factors—business model innovation, digital technology integration, and the development of new competencies—on business performance, considering the sector’s technological intensity as a moderating variable. The results reveal that organizations in medium- and low-technology sectors can significantly benefit from investments aimed at innovating their business models, integrating digital technologies, and fostering the development of new competencies, achieving better outcomes compared to firms in high-technology sectors. These findings suggest that, despite their limited R&D investment, medium- and low-technology firms possess resources and capabilities that compensate for their reduced innovation activities. Keywords: Digital transformation; performance of Spanish manufacturing firms; business model innovation; integration of digital technologies; digital talent management; sectoral technological intensity; knowledge management.

ULTRASONIC METAL WELDING QUALITY PREDICTION MODEL BASED ON MHSA–LSTM–AHP

XIHAO FAN - HUA ZHANG - MEI ZOU - RUIJUAN WANG - JINGCHI ZHANG — 01/07/2025

Ultrasonic Metal Welding (UMW) technology is widely used in industries such as electric vehicle manufacturing owing to its efficiency, low heat input, and ability to join dissimilar metals. However, the weld quality of UMW technology is susceptible to various process parameters; thus ensuring consistency is challenging. A quality prediction model that combines the Analytic Hierarchy Process (AHP), Long Short-term Memory (LSTM), and Multi-head Self-attention (MHSA) was proposed in this study to evaluate the joint quality of UMW technology accurately. The UMW process was analyzed in four stages based on current production operations, with characteristic information extracted from the process characteristic data sampled by the in-line inspection equipment. A hierarchical framework was developed by drawing on the principles of the AHP to elucidate the interrelationships between the real-time process data, the process characteristics, and the UMW joint quality. An MHSA-LSTM-AHP quality prediction model was established in this study by harnessing the advantages of LSTM and MHSA in learning temporal dependencies. A comparative analysis was conducted by using the Genetic Algorithm-optimized Backpropagation (GA-BP) Neural Network and LSTM-AHP models to evaluate the performance of the proposed model. Results indicate that the proposed model performs well in predicting tensile strength and contact resistance, with a mean error of 3.21% and 3.7%, respectively. This study can provide a satisfactory reference for the construction of an online quality monitoring system and the optimization of the UMW process. Keywords: Ultrasonic Metal Welding, Prediction Model, Long Short-term Memory, Analytic Hierarchy Process, Multi-head Self-attention.

EXPLAINABLE NEURAL NETWORKS FOR MODELING MECHANICAL PROPERTIES OF 3D-PRINTED PARTS USING FUSED DEPOSITION MODELING (FDM)

01/07/2025

This article presents a comprehensive methodology to predict critical mechanical properties, such as tensile strength and elongation, of 3D-printed parts using the FDM technique, through the development of an explainable multi-output neural network model. The study considers up to eight printing parameters, including layer height, infill pattern and density, print speed, cooling speed, retraction, material, and bed temperature. Through DoE, a reduced but representative set of experiments was generated, allowing the model to identify existing relationships with only 50 samples. The model achieves strong performance, with R² values above 0.93 and low relative errors (MAE < 5.3?%, RMSE < 6.3?%, MAPE < 7.54?%) for both outputs, ensuring reliable predictions and good generalization. Through the application of explainable artificial intelligence (XAI) techniques based on SHAP values, the most influential printing parameters were identified. Infill density and material type are the most critical factors in predicting tensile strength. In contrast, layer height, material, infill density, and infill pattern were found to be essential for predicting elongation. This approach improves FDM printing of medical devices and facilitates future optimizations, reducing time and resources needed for printing parameter adjustments. Keywords: 3D printing, additive manufacturing, fused deposition modeling (FDM), artificial neural network (ANN), tensile strength, elongation, Explainable AI (XAI), SHAP, Machine Learning

Universidad de Guanajuato (Mexico)

01/07/2025

URGENT IMPULSE FOR SPANISH INDUSTRY: THE PATH TOWARDS A SUSTAINABLE AND RESILIENT FUTURE

[No Consta] — 01/07/2025

In 2020, the European Commission set a crucial target: for the industrial sector’s Gross Domestic Product (GDP) to reach 20% of the Union’s total GDP. This goal is fundamental to Europe’s competitiveness, technological sovereignty and strategic autonomy. Unfortunately, the Spanish industrial sector is still far from achieving this goal. In a global context of uncertainty, resource scarcity and climate urgency, strengthening our industrial base is an urgent necessity. We are not seeking to return to the past, but rather to build an industry of the future: one that is more sustainable, digitalised and resilient.

INTEGRATION AND INFORMATION RETRIEVAL BY MULTIPLEXING VISIBLE TETRACHROMATIC QR CODES EMBEDDED IN PRINTED IMAGES

01/07/2025

SUBSIDENCES ASSOCIATED WITH MINING ENVIRONMENTS AND UNDERGROUND WORKS. CASE OF THE COLLAPSE WITHIN THE LORD DERBY CONCESSION (LINARES-LA CAROLINA MINING DISTRICT)

01/07/2025

CROSS-BORDER ASSESSMENT OF THE BUSINESS ECOSYSTEM SPECIALIZED IN ADDITIVE MANUFACTURING

01/07/2025

DRIVE CIRCUIT DESIGN FOR AEROSPACE SEMICONDUCTOR LASER BASED ON SiC DEVICE

XIAOQIANG ZHANG - YUNFENG WANG - CHUNHUI WANG - DI LIU — 01/07/2025

ERGONOMIC DESIGN OF AN INTELLIGENT ROBOTIC WALKER BASED ON USER PERCEPTION AND NEEDS

ISABEL SEGUI VERDU - LARISA DUNAI DUNAI - VALERIY VYATKIN - DINU TURCANU — 01/07/2025

MODELING, SIMULATION, AND CONTROL OF DISSOLVED OXYGEN IN ACTIVATED SLUDGE WASTEWATER TREATMENT VIA PID CONTROLLER: REDUCING ENERGY COSTS

01/07/2025

COMPREHENSIVE EVALUATION METHOD FOR DISTRIBUTION GRIDS BASED ON COMBINATION WEIGHTING AND MODIFIED TOPSIS

ZHEN LU - JIANG QIAN - YONG YAO - XIAOPENG ZHANG — 01/07/2025

BENDING FATIGUE CHARACTERISTICS OF A REINFORCED MACADAM BASE

HONGJUN JING - XIANGYU CHEN - YUNLIANG ZHANG - GUOPING ZHANG - BINHUI REN — 01/07/2025

ENHANCING INDOOR AIR QUALITY THROUGH NATURAL VENTILATION: INSIGHTS FROM MUNICIPAL BUILDING IN MOSTOLES, SPAIN

01/07/2025

MATHEMATICAL PROGRAMMING FOR THE SELECTION OF THE IDEAL CYCLE LENGTH IN PREVENTIVE MAINTENANCE POLICIES

JAVIER MAQUIRRIAIN ANTOÑANZAS - ALBERTO GARCIA VILLORIA - RAFAEL PASTOR MORENO — 01/07/2025

CONTAMINANT CHARACTERISTICS OF WASTE FOUNDRY SAND: TOXICITY, MECHANICAL PROPERTIES AND USES

01/07/2025

DIGITAL TRANSFORMATION AND THE PERFORMANCE OF SPANISH MANUFACTURING FIRMS: THE ROLE OF INDUSTRY TECHNOLOGICAL INTENSITY AND KNOWLEDGE MANAGEMENT

ESTHER GRIJALVO RUPEREZ - MARTA FOSSAS OLALLA - ANTONIO RODRIGUEZ DUARTE — 01/07/2025

ULTRASONIC METAL WELDING QUALITY PREDICTION MODEL BASED ON MHSA–LSTM–AHP

XIHAO FAN - HUA ZHANG - MEI ZOU - RUIJUAN WANG - JINGCHI ZHANG — 01/07/2025

EXPLAINABLE NEURAL NETWORKS FOR MODELING MECHANICAL PROPERTIES OF 3D-PRINTED PARTS USING FUSED DEPOSITION MODELING (FDM)

01/07/2025

Universidad de Guanajuato (Mexico)

01/07/2025

URGENT IMPULSE FOR SPANISH INDUSTRY: THE PATH TOWARDS A SUSTAINABLE AND RESILIENT FUTURE

[No Consta] — 01/07/2025

ADVANCED EXPERIMENTAL INVESTIGATIONS ON NANOFLUIDS AS QUENCHANTS IN METAL ALLOY HEAT TREATMENTS

01/05/2025

Recently, nanofluids have played an essential role in their use as a cooling medium in various disciplines in both scientific and industrial sectors. There are different fields of study of nanofluids, which have been intensely investigated theoretically, experimentally, and numerically. Metallurgical applications have allowed the implementation of nanofluids as a cooling medium in different applications. This compilation analyzed research on nanofluids as a cooling medium in heat treatments of metals, mainly steel. Factors that affect the heat extraction process in heat treatments and the effect on the microstructure and mechanical properties, such as type of nanoparticles, concentration, base fluids, particle size, temperature, shape, and surfactants, are discussed. Many variables add complexity to the heat extraction process in heat treatment processes. For this reason, research on the use of nanofluids in the heat treatment of steel is minimal, and there are discrepancies in the results obtained by researchers, which implies an enormous potential for further studies on the subject. Keywords: Nanofluids, quenching, heat treatment, heat transfer.

INTELLIGENT ROBOTIC SYSTEM FOR AUTOMATIC IDENTIFICATION OF MARKS ON PARTS

01/05/2025

The increasing market demands are driving companies to develop intelligent robotic cells capable of making autonomous decisions based on their environment. This work addresses the industrial challenge of distinguishing and tracking marked parts throughout the production process, where precision in identifying these parts and their marks poses a significant obstacle. As a solution, the integration of advanced learning techniques into a vision system for pick and place applications with a parallel delta robot is proposed. The developed system uses cubes with serigraphed letters on their top surface, identified through artificial vision to form words and control the process via a graphical interface. To automate letter recognition, an intelligent model based on a Convolutional Neural Network has been implemented, achieving 100% accuracy. Keywords: Delta Parallel Robot, Artificial Vision, Automation, Neural Networks, Machine Learning.

DIMENSIONAL OPTIMIZATION OF 7-DOF AGRICULTURAL ROBOT ARM

01/05/2025

Agricultural automation has emerged as a potential solution to meet the growing need in the quickly changing farming business. For example, the tasks in palm oil plantations require precision, efficiency, and adaptability to navigate the complex environment. Robotics solve these challenges by enhancing farming and executing tasks such as cutting fresh fruit bunches that surpass manual labor. By examining the optimal dimensions synthesis for the robotic arm and integrating the Denavit-Hartenberg (DH) parameters for kinematic modeling, this study aims to enhance the degree of freedom, enabling precise and flexible movements, which is crucial for navigating around palm oil trees. This research evaluates two optimization algorithms, artificial bee colony (ABC) and particle swarm optimization (PSO), specifically tailored for robotic arms in the agricultural sector and intended to improve performance. Kinematic modeling simulations are conducted using MATLAB software. This research emphasizes optimization methods to ensure the accurate and efficient execution of tasks. The results indicate that the PSO algorithm outperforms the ABC algorithm in terms of error minimization. Specifically, the mean square error for PSO is 5.0433 x 10-6, compared to 9.3904 x 10-6 for ABC. These results demonstrate that the PSO algorithm provides more accurate and efficient task execution for the robotic arm in agricultural applications. Key Words: Optimization; Topological; Dimensional; Agricultural; Forward Kinematics; Inverse Kinematics

EVALUATION OF INITIALIZATION METHODS FOR THE PERFORMANCE OF THE K-MEANS ALGORITHM

01/05/2025

The K-means algorithm is one of the most widely used unsupervised machine learning methods; it helps to sort data clusters into a given number of groups with a pattern association that identifies relevant information in research domains. The heuristics of the algorithm are adaptable and easy to implement; however, one of its most notorious weaknesses is the poor assignment of K groups. This paper aims to analyze the different means of initialization and performance of the algorithm, as well as some applications of K-means in different industry sectors through a literature review, addressing relevant aspects to conclude in which cases transcendent results are obtained. Keywords: K-means, heuristic, clustering, performance, initialization, algorithm, centroids, metaheuristic, accuracy, evaluation, methods, applications.

IMPACT ON METHODOLOGY FOR DETERMINING ABSORPTION IN THE FINE FRACTION OF RECYCLED MATERIAL FROM ASPHALT MIXTURES

01/05/2025

One of the most commonly discussed strategies in the construction industry to mitigate the generated environmental impacts is the use of waste, especially that produced on-site. In road engineering, there is a growing trend towards the use of recycled asphalt mix material known as RAP (Reclaimed Asphalt Pavement). This particulate material contains an asphalt binder, so although it is expected that the absorption of the aggregate that makes up the RAP should be reduced, it keeps some remaining water absorption capacity. To evaluate the absorption, the aggregate must be brought to its saturated surface dry condition, which becomes complex to analyze in the fine aggregate (material that passes through sieve No.4 [4.75 mm]). In this paper, this parameter is evaluated in the fine fraction of recycling derived from asphalt mixtures with modified asphalts (RMAP), using two methodologies: the first following the cone method i.e: ASTM C128, IRAM 1520, NTC 237, etc; and the electrical conductivity based on the Japanese standard JSCE-S506-2003. The two are compared, and it is evident which proposed methodology reduces the influence of the operator and impacts of each method. In addition, the results of the recovered asphalt characterization are presented, which, together with the material absorption value, allow the necessary temperature to be adopted to eliminate the water in the r, eservoirs of the RMAPs, producing considerable energy savings.

CONTINUUM PARALLEL MANIPULATORS AS AN ALTERNATIVE TO RIGID ELEMENT MECHANISMS

01/05/2025

Continuum Parallel Manipulators are parallel kinematic mechanisms in which rigid elements have been replaced by very flexible slender rods, eliminating some kinematic joints and maintaining closed-loop kinematic chains. The mobility of the resulting mechanism is due to the combination of kinematic joints and deformability of the slender bars. Its advantages over rigid element mechanisms can be summarized as follows: simpler assembly, lower weight, larger workspace for the same dimensions and lower stiffness. The latter feature implies a lower risk in the case of impacts when the mechanism is designed for collaborative tasks in a non-isolated space where robots and people meet simultaneously, thus possessing a high potential in the field of so-called CoBots. This same characteristic makes it necessary to consider in the design two aspects that do not appear in rigid mechanisms. The main objective of this paper is to explain the basic methodology to be followed when analyzing continuum parallel mechanisms, both planar and spatial, with emphasis on problems that arise due to the incorporation of flexible elements, such as the non-stability of certain solutions and the existence of parasitic movements in spatial mechanisms of low mobility. In the first part, it will be shown how the resolution of position kinematic problems requires that not only geometrical constraint equations are taken into account, but also others that guarantee the equilibrium of forces and moments, also considering the non-linearity of the large deformations of the bars. In general, the problem presents a multiplicity of kinetostatic solutions. In this work, the multiplicity of solutions for the case of planar flexible mechanisms will be addressed, in addition to their stability analysis. In the case of lower-mobility spatial mechanisms, it must be taken into account that these flexible systems are in essence systems with infinite degrees of freedom, so that a complete restriction of motions is not possible. Consequently, in the operation of this subclass of mechanisms, the so-called parasitic motions will appear, inherent to the flexibility of the members, which complicate the kinematic analysis. The present paper analyzes this type of parasitic motions, which until now had only been investigated in rigid manipulators, and shows their evolution in the manipulator workspace. The theoretical analysis of these motions has been contrasted with experimental tests based on the prototype of the flexible Delta manipulator.

STATISTICAL ANALYSIS OF FUZZY RULES FOR HARDNESS PREDICTION IN STEELS USING FUZZY LEAST SQUARES

01/05/2025

This study proposes a methodology based on a Fuzzy Inference System (FIS) to model the tempering process of D2 and H13 tool steels, transforming the FIS into a Fuzzy Least Squares (FLS) model using its rules and membership functions. An ANOVA performed on the FLS model reveals a p-value of 0.000014, indicating high statistical significance. The significance analysis identifies rules 2, 3, and 11 as consistent and relevant (p<0.05 . T_0>T_(a\/2)), with rule 2 showing notable sensitivity within its membership function intervals, essential for accurate predictions. The FLS model (R^2=0.83) significantly outperforms the FIS model (R^2=0.72), demonstrating greater precision in the results. Furthermore, the FLS model simultaneously predicts the hardness of both steels, optimizing costs and time in process control. The new FLS structure enables detailed analysis to identify the most significant rules, marking a key contribution of this work. Keywords: Fuzzy rules; Hardness prediction; Fuzzy Least Squares; Steel tempering; Fuzzy inference; Process modeling; Fuzzy Logic Systems; Steel hardness; Tool steels; Analysis of Variance; Membership functions; Model sensitivity.

ANALYSIS OF SELF-SUPPORTING STRUCTURES IN ADDITIVE LASER POWDER BED FUSION TECHNOLOGY LPBF

01/05/2025

Through additive technologies, a multitude of functional parts can be manufactured thanks to the versatility of the manufacturing process. Some of these advantages include the ability to create rapid metal prototypes, the option to fabricate with various materials, flexibility in production, and cost savings. This technology is constantly evolving and improving. The present work presents a study to evaluate the effects of printing parameters on surface roughness and dimensional accuracy of lower surfaces without the need for support structures. The material used in the study is 316L stainless steel, an austenitic stainless steel commonly employed in additive manufacturing. The analysis focuses on evaluating the relative fusion energy density by modifying four of the most influential parameters in the LPBF process: laser power, scanning speed, hatch spacing, and frequency. Using the design of experiments (DoE) method, the process parameters will be determined, and the significance and contribution of the individual process parameters to each response will be analyzed. This study provides a solution to a problem related to the manufacturing of self-supporting structures in critical angle situations on the Alba 300 printer by SamyLabs. The optimal reduction in energy density is 40% for a critical angle of 36º and a layer thickness of 50µm. Keywords: Laser powder bed fusion, critical angle, support, self-supporting, energy density

CONTEXT EXTRACTION AND EXPRESSION OF PRODUCT IMPROVEMENT FEATURES BASED ON ONLINE REVIEW MINING

01/05/2025

Current research on extracting customer requirements from online reviews is mainly focused on feature extraction and sentiment analysis, often neglecting the context information of product use. This oversight limits the designers' ability to fully understand user interactions with products, hindering effective product design improvements. To address this issue, we propose a method for context extraction and expression of product improvement features based on online review mining. Firstly, a context model was constructed by identifying context elements related to product improvement features. Secondly, a conditional random field (CRF) model was trained to automatically annotate these elements in reviews. Lastly, Chi-square test was conducted to quantify correlations between context elements and product improvement features, ultimately creating a matrix diagram for visualizing design directions. The effectiveness of the method was validated using camera review data as a case study. Key Words: online reviews; product improvement features; customer requirements; context extraction; context expression

SYMPATHETIC INRUSH CURRENT PHENOMENA IN PARALLEL CONNECTED TRANSFORMERS CONSIDERING GRADING CAPACITANCE

01/05/2025

The article presents the results of a research study focused on the phenomenon of sympathetic inrush current caused by the sequential energization of two transformers connected in parallel with another transformer already in operation, introducing the novelty of considering the effect of the circuit breaker's grading capacitance. The aim is to propose an operational practice that reduces the intensity of this phenomenon and minimizes the risk of blackouts or equipment failures during the energization or re-energization of the transformers.The studied system is common in the central Mexican electrical grid and consists of a substation with three 100 MVA transformers. Through these transformers, it is possible to transfer energy between the 230 kV and 85 kV networks. The research employs electrical system modeling using the ATP (Alternative Transients Program) software to simulate common practical cases involving the manipulation of substation circuit breakers during the operation of the power grid. The program allows for controlling the closing time of the circuit breakers to create critical scenarios during the energization process. It also uses a transformer model with saturation characteristics provided by the manufacturer, including a certain level of remanent magnetization. The results show that the magnitudes, waveforms, and durations of both the magnetizing inrush current and the sympathetic inrush current can cause imbalances and affect the normal operation of the electrical system. This may lead to transformer outages due to the incorrect functioning of differential and overcurrent relays or problems with the quality of power within the system. However, the results also suggest that the proper handling of certain circuit breakers can have beneficial effects, reducing the intensity of the phenomenon and improving the quality and reliability of the power supply. Keywords: Sympathetic inrush current, three transformers in parallel, ATP simulation, power systems operation, grading capacitor.

REDUCTION OF THE CARBON FOOTPRINT IN THE CANARY ISLANDS

01/05/2025

Wastewater treatment plants are essential to protect water resources and public health from pollution, but they can also have a negative impact on the natural environment.

A COMPARATIVE ANALYSIS OF BREWERY EFFLUENTS IN AFRICA

01/05/2025

Wastewater produced by the brewing industry has complex characteristics, which pose significant challenges to environmental engineers in the search for effective methods of treatment and reuse. The main objective of this study is to compare the physicochemical properties of wastewater from breweries in Mozambique and South Africa.

ACTIVE FAULT DIAGNOSIS IN AUTOMATED MANUFACTURING SYSTEMS: MODELED USING INTERPRETED PETRI NETS

01/05/2025

This paper deals with active diagnosis in Discrete Event System represented as Interpreted Petri Nets, which have been used to model an automated manufacturing system (AMS). In addition, a fault diagnosis scheme is implemented through residuals in an AMS controlled by a Mitsubishi PLC, which is monitored by an embedded system capable of measuring the current in the controllers in order to share information to the diagnoser, through the Modbus communication protocol with the purpose of increasing its reliability in the pronouncement. Key Words: Interpreted Petri Nets, active diagnosis, Factory IO, diagnosability, fault diagnosis.

QUANTUM COMPUTING IN INDUSTRIAL ENVIRONMENTS: WHERE DO WE STAND AND WHERE ARE WE HEADED?

01/05/2025

This article explores the current state and future prospects of quantum computing in industrial environments. Firstly, it describes three main paradigms in this field of knowledge: gate-based quantum computers, quantum annealers, and tensor networks. The article also examines specific industrial applications, such as bin packing, job shop scheduling, and route planning for robots and vehicles. These applications demonstrate the potential of quantum computing to solve complex problems in the industry. The article concludes by presenting a vision of the directions the field will take in the coming years, also discussing the current limitations of quantum technology. Despite these limitations, quantum computing is emerging as a powerful tool to address industrial challenges in the future. Keywords: Quantum Computing, Quantum Annealing, Quantum Gate-based computing, Tensor Networks, Job-Shop Scheduling.

TRIPARTITE EVOLUTIONARY GAME OF FOOD SAFETY REGULATION DURING STORAGE AND TRANSPORTATION

JINLONG CHEN - JIAYI HU - QIXIA HUANG — 01/05/2025

Food safety has always been a serious social topic, recently highlighted by food safety accidents during storage and transportation which have caused widespread public concern. These incidents reflect the critical need for food transport enterprises to prioritize food safety during storage and transportation, as well as robust government oversight and investment in safety from food consigning enterprises. However, this perspective has been scarcely considered in existing studies. To analyze the dynamic evolution and influence factors of strategies made by stakeholders in food safety regulation, evolutionary game theory was introduced in this study. A tripartite evolutionary game model involving government, food consignors and food carriers during storage and transportation was constructed using Matlab for analysis and verification. Results show that: (1) Food consignors and carriers can be encouraged to input safety factors during storage and transportation and carry out compliant operation if the government increases the fines on enterprises for non-compliant operation, thus elevating the probability of successful regulation. (2) Food consignors can gain certain benefits and enhance corporate reputation through safety input during storage and transportation, which will encourage them to manage their investments strategically. Moreover, the more severe the issues related to food safety during storage and transportation are, the greater the negative impact on the enterprise will be, and this can prompt food consignors to place more emphasis on food safety. (3) If the probability of food consignors exposing food carriers for non-compliant operation increases, the market share loss brought to the carriers due to non-compliant operation and the negative impact arising from this will be higher, and food carriers will pay more attention to the food safety problem. This study enriches the theoretical research on food safety regulation during storage and transportation and provides guiding insights for improving food safety regulation. Keywords: Food safety regulation, Storage and transportation, Tripartite evolutionary game.

ISSUES IN THE DISTRIBUTION OF ELECTRICITY

[No Consta] — 01/05/2025

In recent months, we have heard various comments that, in developed countries, highlight problems in providing sufficient energy for new industrial projects or decarbonisation projects, for the recharging of EVs, for the construction of data centres or digital commerce, and even for new housing developments. As is often the case in times of rapid paradigm shifts in fields with significant intervention from public administrations in the form of regulations and/or investments, it is not uncommon for us to find ourselves lagging behind and suffering setbacks to development.

ADVANCED EXPERIMENTAL INVESTIGATIONS ON NANOFLUIDS AS QUENCHANTS IN METAL ALLOY HEAT TREATMENTS

01/05/2025

INTELLIGENT ROBOTIC SYSTEM FOR AUTOMATIC IDENTIFICATION OF MARKS ON PARTS

01/05/2025