On differential equations associated with perturbations of orthogonal polynomials on the unit circle

In this contribution, we propose an algorithm to compute holonomic second-order differential equations satisfied by some families of orthogonal polynomials. Such algorithm is based in three properties that orthogonal polynomials satisfy: a recurrence relation, a structure formula, and a connection formula. This approach is used to obtain second-order differential equations whose solutions are orthogonal polynomials associated with some spectral transformations of a measure on the unit circle, as well as orthogonal polynomials associated with coherent pairs of measures on the unit circle.Comunidad de MadridUniversidad de Alcal

Towards an ecological index for tropical soil quality based on soil macrofauna

The objective of this work was to construct a simple index based on the presence/absence of different groups of soil macrofauna to determine the ecological quality of soils. The index was tested with data from 20 sites in South and Central Tabasco, Mexico, and a positive relation between the model and the field observations was detected. The index showed that diverse agroforestry systems had the highest soil quality index (1.00), and monocrops without trees, such as pineapple, showed the lowest soil quality index (0.08). Further research is required to improve this model for natural systems that have very low earthworm biomass

Fast and efficient commits for Lazy-Lazy hardware transactional memory

Ingeniería, Industria y Construcció

Systematic XAS study on the reduction and uptake of Tc by magnetite and mackinawite

The mechanisms for the reduction and uptake of Tc by magnetite (Fe3O4) and mackinawite (FeS) are investigated using X-ray absorption spectroscopy (XANES and EXAFS), in combination with thermodynamic calculations of the Tc/Fe systems and accurate characterization of the solution properties (pHm, pe, [Tc]). Batch sorption experiments were performed under strictly anoxic conditions using freshly prepared magnetite and mackinawite in 0.1 M NaCl solutions with varying initial Tc(VII) concentrations (2 × 10−5 and 2 × 10−4 M) and Tc loadings (400–900 ppm). XANES confirms the complete reduction of Tc(VII) to Tc(IV) in all investigated systems, as predicted from experimental (pHm + pe) measurements and thermodynamic calculations. Two Tc endmember species are identified by EXAFS in the magnetite system, Tc substituting for Fe in the magnetite structure and Tc–Tc dimers sorbed to the magnetite {111} faces through a triple bond. The sorption endmember is favoured at higher [Tc], whereas incorporation prevails at low [Tc] and less alkaline pH conditions. The key role of pH in the uptake mechanism is interpreted in terms of magnetite solubility, with higher [Fe] and greater recrystallization rates occurring at lower pH values. A TcSx-like phase is predominant in all investigated mackinawite systems, although the contribution of up to 20% of TcO2·xH2O(s) (likely as surface precipitate) is observed for the highest investigated loadings (900 ppm). These results provide key inputs for an accurate mechanistic interpretation of the Tc uptake by magnetite and mackinawite, so far controversially discussed in the literature, and represent a highly relevant contribution to the investigation of Tc retention processes in the context of nuclear waste disposal

Sistema inalámbrico de adquisición de datos en tiempo real para la caracterización aerodinámica de una turbina eólica

Context:  Wind energy sources utilize renewable, free, and environmentally friendly resources, so there are projects focused on the design of wind turbines to increase their efficiency. Simulations using computational fluid dynamics techniques allow designs to be analyzed. which, are then validated through experimentation and wind tunnel measurements. Method: Data acquisition is performed by using Wind Sensor Rev.P sensors to measure wind velocity, and MMA7361 accelerometer to measure the vibrations generated by the wind in the turbine. Additionally, an ESP32 is required to process and transmit the data via Bluetooth, thus facilitating the installation of the real-time monitoring module inside the wind tunnel. Results: A monitoring module with a sampling rate of 5 ms was obtained, thus allowing real-time data acquisition, with a resolution of 12 bits for good data capturing accuracy and a transmission rate of approximately 74000 bps. An application capable of plotting 3D acceleration and 2D wind speed signals was also created. Conclusions: The device developed serves as a support for future wind turbine design projects since it is wireless, its installation is simple, it facilitates data collection inside a wind tunnel, and it allows visualizing the turbine’s behavior in real time by means of a graphic interface.Contexto: Las fuentes de energía eólica aprovechan recursos renovables, gratuitos y respetuosos con el medioambiente, por lo cual existen proyectos enfocados en diseñar turbinas eólicas para aumentar su eficiencia. Las simulaciones mediante técnicas de dinámica de fluidos computacionales permiten analizar diseños, los cuales son luego validados mediante experimentación y mediciones en túneles de viento. Método: La adquisición de datos se realiza mediante el uso de los sensores Wind Sensor Rev.P para medir la velocidad del viento y del acelerómetro MMA7361 para medir las vibraciones generadas por el viento en la turbina. Adicionalmente se requiere una ESP32 para procesar y transmitir los datos mediante Bluetooth, facilitando la instalación del módulo de monitoreo en tiempo real dentro del túnel de viento. Resultados: Se obtuvo un módulo de monitoreo con una frecuencia de muestreo de 5 ms, lo que permite la adquisición de los datos en tiempo real, con una resolución de 12 bits para una buena precisión en la toma de datos y una velocidad de transmisión de aproximadamente 74000 bits por segundo. También se creó una aplicación capaz de graficar las señales de aceleración en 3D y velocidad del viento en 2D. Conclusiones: El dispositivo desarrollado sirve como soporte para futuros proyectos de diseño de aerogeneradores, ya que es inalámbrico, su instalación es sencilla, facilita la recolección de datos dentro de un túnel de viento y permite visualizar el comportamiento de la turbina en tiempo real mediante una interfaz gráfica

Analysis of navigational interfaces through the use of knowledge representation schemes

(Spa) Actualmente la mayoría de repositorios digitales incluyen esquemas de representación de conocimiento como ontologías y tesauros para ofrecer a creadores y expertos varias alternativas que permitan gestionar, clasificar y organizar objetos de aprendizaje dentro de un repositorio; así como facilitar el uso del repositorio para ayudar a los usuarios a localizar objetos de aprendizaje, desplegar información complementaria, identificar sus relaciones, categorías, áreas de conocimiento, etc. Sin embargo, estos esquemas de clasificación a veces no son utilizados y aprovechados en la medida que sería deseable debido a: i) los usuarios no están familiarizados con los complejos sistemas de representación de conocimiento, que los expertos y creadores de repositorios utilizan para clasificar los recursos, y ii) las interfaces de usuario actuales no siempre facilitan las tareas esenciales de los usuarios que visitan el repositorio: búsqueda y localización de recursos digitales. La motivación de este artículo se centra en el segundo factor, presentando un análisis de las deficiencias de las actividades de búsqueda y navegación mediante el diseño e implementación de interfaces navegacionales a partir del uso de esquemas de representación de conocimiento.(Eng) Currently, the most digital repositories include knowledge representation schemes such as ontologies and thesauri in order to offer to creators and experts several alternatives able to manage, sort and organize learning objects within a repository. Also facilitate the use of the repository to help users locate learning objects, displaying additional information, identify relationships, categories, areas of expertise. However, these classification schemes sometimes have not been used and exploited to the extent desirable due to: i) users are not familiar with the complex systems of knowledge representation, which experts and creators of repositories used to classify resources, and ii) the current user interfaces do not always provide the essential tasks of users who visit the repository: search and locate digital resources. The motivation of this article focuses on the second factor, presenting a gap analysis of the activities of search and navigation through the design and implementation of navigational interfaces from the use of knowledge representation schemes

Adquisición de datos con tecnología IoT LoraWAN para monitoreo de turbinas eólicas bio-inspiradas en zonas rurales de Cundinamarca

Context: The energy crisis is a global problem. In Colombia, research aimed at the efficient use of renewable energies is being conducted. For example, in the case of bio-inspired wind generators, a monitoring system is required to observe the output variables (voltage and frequency). Method: LoRaWAN technologies are used to deploy the wireless link since the generators are separated from the base station. In addition, the Gateway coverage area is simulated with HTZ Communications software for future smart grid improvements. Results: The implemented system allows constant monitoring over a long period of time and stores its information in online, open-source databases, which allows remotely visualizing the status of the network, with a total of 3 samples per minute and a range of up to 3,47 km. Conclusions: The data acquisition system can be implemented for remote monitoring. Moreover, since it is a low power system, it can be utilized in non-interconnected areas, as well as for storing data for up to 6 months. However, for the characterization of a model of wind generators, it is advisable to modify the system so that the sampling time is lower.Contexto: La crisis energética es una problemática global. En Colombia se están realizando investigaciones para el aprovechamiento eficiente de energías renovables. Por ejemplo, en el caso de generadores eólicos bio-inspirados, se requiere un sistema de monitoreo para observar variables de salida (voltaje y frecuencia). Método: Se utilizan tecnologías LoRaWAN para el despliegue del enlace inalámbrico, ya que los generadores están separados de la estación base. Además, la zona de cobertura del Gateway se construye en el software HTZ Communications para futuras mejoras en la red inteligente. Resultados: El sistema implementado permite realizar un monitoreo constante por periodos de tiempo prolongados y almacena su información en bases de datos online de código abierto, lo cual permite visualizar el estado de la red de forma remota, con un total de 3 muestras por minuto y un alcance de hasta 3,47 km. Conclusiones: El sistema de adquisición de datos puede ser implementado para monitoreo remoto. Adicionalmente, dado que es un sistema de baja potencia, puede utilizarse en zonas no interconectadas, así como para almacenar datos hasta por 6 meses. Sin embargo, para la caracterización de un modelo de generadores eólicos, es aconsejable modificar el sistema para que el tiempo de muestreo sea menor