Treated wastewater is commonly used for park irrigation in arid zones of Mexico without considering groundwater contamination. The objective was to investigate the possibility of nitrogen compounds leaching into the groundwater and their subsequent reactions in the main types of soils. Lysimeters samples were taken to scrutinize the soil characteristics of the green areas irrigated with treated wastewater from the Northern Wastewater Treatment Plant in the city of Chihuahua. Testing samples were setup to recreate treated wastewater irrigation conditions. Nitrogen-based compounds were identified and measured before and after percolation through the soil columns. Based on the results, one meter of sand column was sufficient to remove 68 to 100% of nitrogen compounds present in the residual water. The removal of all nitrogen-based compounds as they percolate through one meter of clay soil column was not enough, due to the biochemical reactions that occur through the percolation process. Results indicate minimal risk of nitrate and nitrite leach into the aquifer, since the average static level depth is 20 m which provide broad filtration. This demonstrates an opportunity for in-situ investigations to reevaluate the standards for soil aquifer treatment recharge, based on the soil type and water quality of the area.
Groundwater is the main source of water in arid cities where precipitations are low and not evenly distributed. The combined impact of climate variability and intensive human activities has caused a substantial decline in groundwater levels. Understanding the response of groundwater levels to meteorological and anthropogenic factors is a key step to propose water management alternatives. Meteorological and groundwater data were used to design a multi-step approach to assess the influential factors on the groundwater system in the City of Chihuahua, Mexico. The analysis of historical groundwater levels and climate showed a clear increase in meteorological drought, as well as a groundwater abstraction trend since 1986. Rainfall, groundwater recharge, and groundwater level displayed a significant decrease. Overall, the groundwater depth is continuously increasing with a strong correlation with groundwater abstraction. Despite having a significant trend, the changes in land-cover, groundwater recharge, and meteorological drought were not the main factors inducing the decreased level of water in the aquifer. The continuous abstraction of groundwater from 1986 to 2010 has led to a depletion of groundwater levels from 32 to 92 m. The findings of this study lay a foundation for future water resource management in the study area.
ResumenEl hueso, al igual que las demás estructuras biológicas se adaptan continuamente a su entorno físico, se ha aceptado ampliamente que el tejido óseo responde a la estimulación mecánica, se reabsorbe en regiones expuestas a estímulos mecánicos de baja intensidad, mientras que se renueva donde estos son altos. Se cree que el proceso de adaptación permite al hueso realizar sus funciones mecánicas con un mínimo de masa. A partir de esta idea muchos modelos teóricos para la remodelación ósea utilizan este concepto como parte de la estrategia para simular la adaptación estructural ósea. Lo que implican la existencia de un estado de equilibrio donde la estructura ósea se adapta al medio ambiente. Esto ha dado origen al desarrollo de modelos computacionales que, por una parte, suponen una estructura trabecular isotrópica, cuyos resultados muestran las similitudes en la distribución de densidad del hueso in vivo, aun así se considera que no es posible obtener una solución convergente, por otra parte se han desarrollado modelos considerando la naturaleza anisotrópica del hueso trabecular en el nivel continuo haciendo uso de los principios de optimización; Sin embargo, a pesar de las similitudes con el comportamiento real, los modelos, representan simplemente una abstracción matemática de la arquitectura trabecular. El objetivo de este trabajo es mostrar los modelos de adaptación ósea que emplean una aproximación matemáticos para caracterizar las propiedades mecánicas de la estructura del hueso.Palabras clave: Hueso, estímulo, remodelado óseo, densidad de energía de deformación AbstractThe bone as biological structure is continually adapting to changes in their physical environment, it has been widely accepted that bone respond to mechanical stimulation, tissue is resorbed in regions exposed to low mechanical stimulus, whereas new bone is deposited where the stimulus is high. This process of adaptation is thought to enable bone to perform its mechanical functions with a minimum of mass. From this idea, many theoretical models for bone remodeling use this concept as part of the strategy to simulate bone structural adaptation. What implies the existence of an equilibrium state where the bone structure is adapted to the environment. That is the origin to develop of computational models were, on one hand, the assumption of isotropy of the trabecular structure is made. The results show the similarities in density distribution with in vivo bone, as well as a convergent solution cannot be obtained. To another part, models have been developed to consider the anisotropic nature of the trabecular bone in the continuum level making use of optimization principles;
En el presente artículo se describen los aspectos importantes de la metodología de diseño, la fabricación y el modelado cinemático de un robot manipulador de tres grados de libertad. El manipulador robótico diseñado tendrá fines educativos e investigación y será utilizado en el área de robótica en la Escuela Superior de Ciudad Sahagún-UAEH. Se presenta la propuesta de diseño de un robot manipulador de 5 barras similar al IRB1400 de ABB. Se utilizan motoreductores con encoders de cuadratura y como adquisición de datos una tarjeta Arduino. Se calcula la cinemática directa e inversa del manipulador, mediante el uso de los parámetros de Denavit-Hartenberg. Se realizan pruebas de simulación del comportamiento del robot y la validación del modelo cinemático.
Históricamente, la ciencia de la termodinámica se desarrolló para proporcionar un mejor conocimiento de los dispositivos, conocidos como máquinas térmicas, que absorben calor desde una fuente de alta temperatura y producen trabajo útil. En el presente trabajo se examinan los sistemas empleados en la generación de energía.
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