No abstract

<p>This paper presents a descriptive study aimed at identifying the main active ingredients, frequency of use, and the processes employed in the application of the agrochemicals most used around the Lake of Tota, which is considered the most important freshwater ecosystem in Colombia. A key source for this study is a survey to farmers, which sampling frame was established from a Geographical Institute Agustin Codazzi (IGAC) digital map, considering only the plots with some agricultural activity and runoff into the lake. This information was supplemented with geographic data obtained from Google Maps®. As control mechanism, two additional sources were used: i) a manual count of packaging of agrochemicals in a certified collection center, and ii) a census of stores that supply such products in the study area. The results allow knowing the set of agrochemicals most used around the lake, their active ingredients, and the most common farming practices, some of which could entail some risk to farmers, consumers and the environment.</p>

Educational robotics has become one of the most effective methods to teach STEM concepts in a practical and didactic way at all educational level. In this context, the LEGO Mindstorms robotic platforms have been widely used due to their versatility ease of use and modularity. Despite this, most of the papers focus on K-12 and undergraduate levels, with little information reported in the literature about educational experiences at the graduate level. This article deals with the use of educational robotics for the teaching of mathematical concepts at the graduate level, and more specifically on the physical visualization of metrics (Euclidean, Taxicab, and Infinity), and the convergence of Cauchy's succession using a mobile robots LEGO Mindstorms NXT. The educational experience was applied to a group of graduate students who offered good comments on this type of educational activity and its usefulness to understand the mathematical concepts addressed. It was observed that this type of educational experiences motivates students to use mathematical concepts in interdisciplinary problems and encourages them to understand their functionality and application in the real world.

Los encoders de cuadratura son los sensores más ampliamente utilizados para medir la posición, velocidad y aceleración de motores. Para su correcto funcionamiento se requiere la implementación de circuitos de decodificación basados en el conteo de pulsos y la determinación de la dirección de rotación, que consideren el uso eficiente de recursos y la eliminación de errores. Dichos circuitos se implementan usualmente en microcontroladores; sin embargo, las FPGAs tienen características que las hacen ideales para este tipo de aplicaciones. En este trabajo se presenta un módulo IP para el acondicionamiento de cuatro encoders de cuadratura, que genera valores de conteo para cada encoder en una base de tiempo que puede ser determinada interna o externamente y elimina los errores que se presentan en los cambios de dirección de rotación. Se presentan los resultados de simulación de la descripción de hardware y su implementación en un robot móvil basado en FPGA.

This work presents a pipeline implementation of the COordinate Rotation DIgital Computer (CORDIC) algorithm in VHDL. This implementation computes both the trigonometric (sine, cosine, and arctangent of two parameters) and hyperbolic (hyperbolic sine, hyperbolic cosine, and hyperbolic arctangent) fixed-point functions. The implementation was synthesized on a Xilinx ® Zynq UltraScale + ZCU102 FPGA evaluation board, reaching an operating frequency of 297.89 MHz. The results show the proper operation of the proposed architecture, achieving relative errors of less than 1.4% for a 16-bit fixed-point representation. The VHDL implementation is easily adjustable to meet the specific requirements of each system and is available as an open-source code under a Creative Commons license.