Papers by Juan L Hernandez
Workers around the world face major changes in work organization and industrial relations to fulf... more Workers around the world face major changes in work organization and industrial relations to fulfill the demands of modern working life. The problem of work stress and obesity have become rather delicate subjects because of the negative consequences it brings for employees and companies. The objectives of this research perform a descriptive analysis using the SPSS v.23 software on work stress, physical activity, eating habits and obesity in the industry for sample characterization. Methods entail the application of a questionnaire for gathering information, the creation of the database in the software and the accomplishment of the descriptive analysis of each section of the questionnaire with the help of the software. As results, physical activity is that all three dimensions show the degree of sedentariness as values fall below 9. As for the diagnosis of eating habits, from the resulting scores, the population shows a diagnosis of food anxiety since all the dimensions of the instrument were among the mean values obtained. As conclusions, manufacturing industries must take preventive actions to reduce them by increasing physical activity and improving eating habits among staff. It is also recommended to implement techniques to improve health, ergonomics and safety practices in the manufacturing industry, so it is that all three dimensions engage in more activity that is physical.
In book: Advances in Additive Manufacturing, Modeling Systems and 3D Prototyping, 2019
The optimization strategies development by the industry of additive manufacturing have been diver... more The optimization strategies development by the industry of additive manufacturing have been diversified according to the pre-process, process, and post-process always based on the manufacturers’ and customers’ needs. The present research exposes an analysis of the characteristics and properties of geometries that must be considered during the design process of elements that will be manufactured using Fused Filament Fabrication (FFF). The methodology integrated three phases: a literature review as the first phase, development of geometries and integration of templates as a second phase, and the analysis of geometries and template number five in the FFF software pre-printing process as a third phase. As a result, a set of five modified geometries and five templates are presented. Each one proposes the characteristics that could be considered by designers, manufacturers, and users of FFF.
Las personas, en ocasiones, pueden sentirse abrumadas al tratar de interactuar con la tecnología ... more Las personas, en ocasiones, pueden sentirse abrumadas al tratar de interactuar con la tecnología moderna. Ciertos productos de uso cotidiano cuentan con diseños deficientes, por lo que pueden provocar una experiencia insatisfactoria y frustración, produciéndose con ellas una carga mental en el usuario que pueda inducir al error. El uso de técnicas para la identificación del error humano y de la evaluación de carga mental en el diseño y evaluación de productos, puede proporcionar información relevante y útil, para mejorar la experiencia del usuario. El objetivo de este trabajo fue proponer una metodología para integrar la evaluación de carga mental y el análisis del error humano en el diseño de productos. Se evaluó la carga mental mediante la técnica perfil de carga de trabajo, Workload Profile (WP), y se utilizó una metodología de identificación del error humano, Task Analysis For Error Identification (TAFEI), en la configuración de audífonos inalámbricos. Diez usuarios participaron voluntariamente en el estudio; sus experiencias en el uso de los audífonos fueron videograbadas. Se utilizaron formularios para evaluar carga mental, y se identificaron errores humanos durante la etapa de configuración de los audífonos con el teléfono móvil. El método utilizado en este trabajo ofrece una mayor sensibilidad en la evaluación de la carga mental y permite determinar los recursos de atención que más se utilizan en la realización de la tarea. Se detectaron dos oportunidades de rediseño, una relacionada con la señal lumínica, y la otra para la identificación de las puntas para cada oído. A partir de los resultados de la aplicación de la metodología propuesta en este estudio, los diseñadores pueden mejorar la interacción entre las personas y los productos.
Lab: Ergonomic and Product Design Lab, 2019
The objectives of the research were to identify the different equations used during the evaluatio... more The objectives of the research were to identify the different equations used during the evaluation of mental workload with the NASA Task Load Index (TLX) and to compare the results achieved with the different equations. A survey consisted of 21 questions was administered to 120 students from the Autonomous University of Ciudad Juarez using the four different equations identified. The scores of the dimensions and the Global Workload Index (GWI) showed differences in the results between the equations employed in this research.
In book: Ergonomía Ocupacional: Investigaciones y Soluciones, Vol. 12Publisher: Sociedad de Ergonomistas de México A.C, 2019
Resumen: El siguiente trabajo, presenta un estudio de caso de análisis del error humano en una ta... more Resumen: El siguiente trabajo, presenta un estudio de caso de análisis del error humano en una tarea ejecutada en un centro de reparación de equipos de cómputo. Por lo que se realizó un Análisis Jerárquico de Tareas, así como aplicación de dos técnicas de identificación del error humano, TAFEI y SHERPA. Como resultado, en TAFEI se elaboraron 11 SSD que ayudaron a identificar 5 transiciones ilegales y 5 modos de error, siendo uno de ellos catastrófico. Una vez analizados y comparados los resultados de TAFEI y SHERPA, se pudieron encontrar errores debido a la mala ejecución de la tarea, mal identificación de los equipos en reparación, daños por mal manejo de los materiales y errores en la colocación de los componentes. Palabras clave: Ergonomía cognitiva, error humano, análisis jerárquico de tareas, TAFEI, SHERPA. Relevancia para la ergonomía: Por medio de este trabajo se presenta un caso de estudio en donde se hacen uso de técnicas de identificación de error humano (SHERPA y TAFEI), las cuales a pesar de ser de gran importancia han sido muy poco aplicada en campo, por lo que se presenta como una posible referencia para todos aquellos que deseen implantar dichas técnicas. Abstract: The following paper presents a case study of the analysis of human error in a task performed in a computer equipment repair center. Therefore, a Hierarchical Task Analysis was performed, as well as the application of two human error identification techniques, TAFEI and SHERPA. As a result, TAFEI developed 11 SSDs that helped identify 5 illegal transitions and 5 error modes, one of which was catastrophic. Once the results of TAFEI and SHERPA were analyzed and compared, errors could be found due to the bad execution of the task, bad identification of the equipment being repaired, damages due to bad handling of the materials and errors in the placement of the components.
Project: Optimization of the extrusion path in the fabrication of elements using Fused Deposition Modeling, 2018
The paradigm of the manufacturing systems was broken in 1980 with the beginning of the Additive M... more The paradigm of the manufacturing systems was broken in 1980 with the beginning of the Additive Manufacturing (AM). This technology has been considered as the complement of the classic manufacturing technology, where the material is removed from a raw material until getting the final product. The addition of material in layers have been considered the new alternative to face the impact in the environment, the economy of materials and process, and the opportunity to generate new complex shapes limited by the classic manufacturing technology. The present chapter exposes the advances of the Fused Deposition Modeling (FDM), one of the seven technologies of AM which is mostly used during the past three decades. In this field, different adaptations and investigations of the technology have been focused on the increment of the capacity of the production system and improve the quality generated by this technique. The methodology used to determine the advance of AM was to employ a Systematic Literature Review using databases. The search was developed considering the keywords of AM for the construction of specific search syntax of documents associated with this technology. The documents obtained were analyzed to identify the progress in this technology. The results present the advancements of the FDM as a technology that change the industrial processing to customize the process, where the globalization makes possible to have this technology available at each desk.
In book: Managing Innovation in Highly Restrictive Environments, 2018
Emotional design, since its birth in the 70s, has developed into becoming one of the main forces ... more Emotional design, since its birth in the 70s, has developed into becoming one of the main forces that drive design nowadays. The capability of understanding the user’s feelings and emotions is considered to be a pivotal part of the design process. More than ever before, industrial designers need to consider the emotional side of consumers to create meaningful and successful products. The present study created a series of recommendations for Industrial Design Conceptualizing based on Emotional Design. These were developed through the analysis of several design emotion-based methodologies, conceptualization theories, and emotional design itself. The recommendations were developed to be applied in the conceptualization phase, for it is at this stage of the design process when the designer gives shape to the initial concept that will ultimately become a product. After its completion, to validate the recommendations, these were handed to a group of eight industrial design students who applied them on one of their academic projects. The results of their works were subjected to analysis to determine the impact on their projects. Students were also asked their opinion about emotional design and the recommendations they were given. Principal results evidence that only the 15% of the students knew about emotional design before being introduced by the present research. Five out of eight of the resulting projects managed to incorporate values and concepts related to emotional design. It reflects that the resulting ultimate products can be influenced by the capabilities of designers to use the recommendations. It could be concluded that the recommendations could be of great interest for industrial design to transmit emotions to products which could satisfy consumers emotional desires.
In book: Advanced Macroergonomics and Sociotechnical Approaches for Optimal Organizational , 2018
As cognitive tasks have displaced physical tasks in today's manufacturing industry, this sector c... more As cognitive tasks have displaced physical tasks in today's manufacturing industry, this sector can demand high levels of mental workload from workers. In certain situations, there is a high cognitive load, which affects operators reducing their attention to the task and causing them mental fatigue and distractions, resulting in errors that generate economic costs or even injuries to workers. This literature review aims to provide a comprehensive understanding the use of mental workload in the manufacturing sector. The methodology consisted of conducting a search in four databases. In the search, a combination of keywords was used, classifying each journal according to the mental workload evaluation means, the type of evaluation, and the area of application. Articles not focusing on the manufacturing area were discarded. Of the total of 3839 articles found, 12 have been selected. Regarding the methods used for mental load assessment, the analytic techniques were found to be the most frequently used.
Project: MACROERGONOMIC COMPATIBILITY INDEX FOR MANUFACTURING SYSTEMS, 2018
In book: New Perspectives on Applied Industrial Tools and Techniques, 2018
The determination of product dimensions is usually a complicated task developed during the design... more The determination of product dimensions is usually a complicated task developed during the design process. Typically, product dimensions are developed using wrong percentiles and wrong anthropometric data, i.e., designers use data from other populations. This chapter proposes a method for dimensioning products based on user–product interactions and the user’s anthropometric dimensions. The methodology includes 7 steps: (1) determine the objective of the product, (2) identify the interactions user–product, (3) assign a name to the product dimensions, (4) identify the user dimensions to design the product, (5) determine the percentiles and Z-scores for each product dimension, (6) calculate the percentiles, (7) determine the dimensions of the product. In order to exemplify the proposed method, two examples were developed using the methodology. The first was related with the design of a conventional bench, and the second was related with design of an adjustable school desk. After applying the proposed method, both products were successfully dimensioned.
In book: Advances in Additive Manufacturing, Modeling Systems and 3D Prototyping, 2019
The optimization strategies development by the industry of additive manufacturing have been diver... more The optimization strategies development by the industry of additive manufacturing have been diversified according to the pre-process, process, and post-process always based on the manufacturers’ and customers’ needs. The present research exposes an analysis of the characteristics and properties of geometries that must be considered during the design process of elements that will be manufactured using Fused Filament Fabrication (FFF). The methodology integrated three phases: a literature review as the first phase, development of geometries and integration of templates as a second phase, and the analysis of geometries and template number five in the FFF software pre-printing process as a third phase. As a result, a set of five modified geometries and five templates are presented. Each one proposes the characteristics that could be considered by designers, manufacturers, and users of FFF.
Th e research propose s a structural equation model (SEM) that integrates four latent variables: ... more Th e research propose s a structural equation model (SEM) that integrates four latent variables: human resources skills, fl exibility, agility, and the economic supply chain (SC) performance for wineries that together include fi fteen observed variables. Th e data was obtained from 64 surveys applied to managers in the wineries in La Rioja, Spain. Direct, the indirect and total eff ects are analysed to prove six hypotheses that relate the aforementioned latent variables. Th e results indicate that the skills of human resources are a source of fl exibility and agility in the supply chain for wineries in La Rioja and thus a direct and indirect source of economic performance.
Companies seek to stand out from their competitors and react to other competitive threats. Making... more Companies seek to stand out from their competitors and react to other competitive threats. Making a difference means doing things differently in order to create a product that other companies cannot provide. This can be achieved through an innovation process. This article analyses, by means of a structural equation model, the current situation of Mexican maquiladora companies, which face the constant challenge of product innovation. The model associates three success factors for new product development (product, organization, and production process characteristics as independent latent variables) with benefits gained by customers and companies (dependent latent variables). Results show that, in the Mexican maquiladora sector, organizational characteristics and production processes characteristics explain only 31% of the variability (R 2 = 0.31), and it seems necessary to integrate other aspects. The relationship between customer benefits and company benefits explains 58% of the variability, the largest proportion in the model (R 2 = 0.58).
This study used Structural Equation Modeling (SEM) to test the relationship between workload and ... more This study used Structural Equation Modeling (SEM) to test the relationship between workload and fatigue dimensions, using data obtained from among Constant Velocity (CV) joints assembly workers in Mexico. Three years before this study, assembly workers had complained about how their job's high workload had increased their levels of fatigue. The NASA-TLX and the Swedish Occupational Fatigue Inventory ware used to collect data on the effects of workload on fatigue from 116 assembly workers. A structural equation model was used to test five hypotheses associated on the effects of workload on lack of energy, physical effort, physical discomfort, lack of motivation, and sleepiness. All relationships were significant and had associated positive load factors. As a result, the modified structural equation model showed statistical significance, as well as good mode fitness. From these results, fatigue was supported as being substantially affected by the workload.
The main objective of this research was to build a database on anthropometric features from a sam... more The main objective of this research was to build a database on anthropometric features from a sample of students enrolled in the Industrial Design program at the Universidad Autonoma de Ciudad Juarez (UACJ), to contrast anthropometric data with other Mexican regions, and to generate predictive models of the participants' body dimensions. A set of 36 body dimensions were measured based on international standards. Two anthropometric kits Rosscraft model Centurion were used for measurements. 140 students, 70 male and 70 female, enrolled in the Industrial Design program at the UACJ were measured. The values of mean, standard deviation, and percentiles were calculated. Besides, 26 predictive models of body segments were developed using simple linear regression. Body weight and stature of students in Northern Mexico are significant larger than people from other Mexican regions. We now hold anthropometric data of 36 body dimensions and 26 predictive models of body segments.
Resumen—El estudio investiga los daños físicos que causa la falta de mobiliario escolar apto para... more Resumen—El estudio investiga los daños físicos que causa la falta de mobiliario escolar apto para niños zurdos. Se utilizó una metodología cuantitativa y el instrumento empleado fue una encuesta con respuestas de opción múltiple. Los resultados mostraron que el 13% de las personas encuestadas son zurdas y que el 53% al escribir en una banca para diestros tienen un grado medio de dificultad. El 92.3% dijeron que después de permanecer sentados durante día de clases se les presenta dolor en la espalda y el 38.4% en la muñeca y cuello. El 30.7% escriben en forma de mano de gancho y el 23% presionando convulsivamente contra la hoja de papel. El 61.5% se manchan de lápiz la mano siempre que escriben. Estos resultados fueron relacionados con investigaciones previas y se comprobó que la falta de mobiliario para personas zurdas sí les causa daños físicos.
Resumen-Las molestias en el cuello y en las extremidades de la parte superior son comunes en la s... more Resumen-Las molestias en el cuello y en las extremidades de la parte superior son comunes en la sociedad actual, debido a la manipulación cotidiana del teclado computacional. El objetivo de esta investigación fue analizar qué impacto provoca en los usuarios el uso cotidiano del teclado de computadora e identificar la mejor opción de diseño de teclados analizando diseños ya existentes. Se aplicaron 31 encuestas a trabajadores (hombres/mujeres) de entre 21 y 52 años de la empresa automotriz Delphi que trabajan diariamente frente a una computadora; el 61% utiliza computadora portátil en el ámbito laboral. Los trabajadores reportaron sentir molestias en el cuello, hombros y muñecas al manipular una computadora.. La implementación de la ergonomía en el teclado computacional ayuda a reducir tensiones en los músculos. Sin embargo, no cuenta con la aceptación esperada en los usuarios.
Usually, agricultural tractor investments are assessed using traditional economic techniques that... more Usually, agricultural tractor investments are assessed using traditional economic techniques that only involve financial attributes, resulting in reductionist evaluations. However, tractors have qualitative and quantitative attributes that must be simultaneously integrated into the evaluation process. This article reports a hybrid and multi-attribute approach to assessing a set of agricultural tractors based on AHP-TOPSIS. To identify the attributes in the model, a survey including eighteen attributes was given to agricultural machinery salesmen and farmers for determining their importance. The list of attributes was presented to a decision group for a case of study, and their importance was estimated using AHP and integrated into the TOPSIS technique. In this case, one tractor was selected from a set of six alternatives, integrating six attributes in the model: initial cost, annual maintenance cost, liters of diesel per hour, safety of the operator, maintainability and after-sale customer service offered by the supplier. Based on the results obtained, the model can be considered easy to apply and to have good acceptance among farmers and salesmen, as there are no special software requirements for the application.
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Papers by Juan L Hernandez