Introduction: Food security is the state in which all persons always have access to the food needed according their biological requirements, but since 2002, the FAO has mentioned that food security cannot be achieved without considering the access to water. Objective: To identify the state of food security and access to water in Mexican households. Methods: Food Security was assessed using a validated scale applied in 352 households in rural and urban communities, as well as a pilot scale to assess access to water. Results: 73 % of households were classified as food secure (level 1), 15 % as being mildly food insecure (level 2), 7% were considered food insecure at a moderate level (level 3) and only 4 % were households with severe food insecurity (level 4). At all food security levels interviewees were worried about not having enough access to water, and in the last three months 50% of households experiences water scarcity. Most of the households used tap water to prepare the milk for the children, as well as for personal hygiene. 25% of the interviews reported that water availability has declined in their households, while the cost of water has increased. Conclusions: Food security cannot be conceived without taking into account the water situation. The majority of the households report lack of access to enough water, which usually does not meet the conditions of safety for human consumption and food preparation. Grant Funding Source: None funding

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Control engineering and state-space representation are valuable tools in the analysis and design of dynamic systems. In this research, a methodology is proposed that uses these approaches to transform a system-dynamics simulation model into a mathematical model. This is achieved by expressing input, output and state variables as input, output and state vectors, respectively, allowing the representation of the model in matrix form. The resulting model is linear and time-invariant, facilitating its analysis and design. Through the use of this methodology, the system transfer matrix is obtained, which allows the analysis and design of the optimal control of the simulation model. The Ackermann gain-control technique is used to determine the optimal control of the system, which results in a shorter settlement time. This research proposal seeks to mathematically strengthen simulation models and provide an analytical alternative through modern control engineering in SD simulation models. This would allow more informed and effective decisions in the implementation of dynamic systems.

El presente trabajo de investigación tiene como objetivo analizar las principales dificultades que enfrentan estudiantes del nivel medio superior en su aprendizaje matemático, por medio de actividades que nos indiquen los errores más comunes que enfrentan los estudiantes en la institución educativa en la preparatoria Federal por cooperación Lázaro Cárdenas, ubicada en Prolongación 5 de mayo de la ciudad de Yuriria- Guanajuato-México. La investigación se desarrolló bajo un enfoque cuantitativo, con una muestra poblacional de 15 estudiantes, debido al sistema hibrido que se cumple en la actualidad en las instituciones educativas de la región por la Pandemia ocasionada por el COVID 19. La recolección de datos fue obtenida por medio de un examen práctico en el que se evalúa la capacidad para resolver los ejercicios y los diversos errores que muestran en la misma resolución, mediante ejercicios matemáticos. La construcción del examen se realizó mediante una investigación exhaustiva del marco teórico y estado del arte del tema, mismos que fueron evaluados por diferentes académicos de la institución educativa, se obtiene los resultados de examen práctico y en base a los resultados se determinan cuáles son las principales dificultades que los estudiantes en el área matemática. Los resultados de la investigación muestran que los estudiantes tienen los conocimientos básicos para la resolución de ejercicios matemáticos, pero asimismo muestran deficiencia para la elaboración y resolución de problemas más complejos.

This research proposes a methodology based on control engineering, transforming the simulation model of system dynamics into a mathematical model expressed as a system transfer function. The differential equations of a time domain present in the Forrester diagram are transformed into a frequency domain based on the Laplace transform. The conventional control engineering technique is used to present and reduce the dynamic system in a block diagram as a mechanism for determining the structure of the system. The direct path equation and the feedback equation are determined to obtain mathematical models that explain the trajectory of the behavior of each state variable through a transfer function in response to the different inputs of the system. The research proposal is based on presenting an alternative of analytical validation for more robust decision-making to systems dynamics models, based on the explanation of the system structure through a transfer function and its analysis of stability and external controllability for the system dynamics model under study. The results are visually analyzed in a root diagram.