Repetitive Movements in Melon Cultivation Workers under Greenhouses

Musculoskeletal disorders cause serious problems that affect workers in many sectors. The objective of this study is the ergonomic analysis of melon cultivation farmers in Almeria-type greenhouses. For this, the rapid upper limb assessment (RULA) method has been applied after carrying out a detailed process of observing the farmers’ tasks. The study shows that 65% of the postures have a very-high-risk level, 26% high, 9% average, and no posture is found with a low risk. They also show that in 69.57% of the postures, the upper limbs are less affected than the others such as the neck, trunk, and lower limbs. Measures are proposed to improve the working conditions for workers

Estrategia de superación metodológica para los entrenadores de baloncesto en la enseñanza de la táctica

The objective of the present research is to develop a methodological overcoming strategy for basketball coaches in the teaching of tactics. Theme of vital importance and relevance to the challenges of modern sport. For the realization of the research a sample of 24 coaches with an average of 14 years in their work as basketball coaches is taken. A systematization of the theoretical foundations that sustain the tactical preparation in basketball is carried out and the strategy is elaborated, which will allow raising the preparation of these professionals, contributing to the acquisition of pedagogical-professional skills.En la presente investigación se plantea como objetivo elaborar una estrategia de superación metodológica para los entrenadores de baloncesto en la enseñanza de la táctica. Temática de vital importancia y actualidad ante los retos del deporte moderno. Para la realización de la investigación se toma una muestra de 24 entrenadores con una media de 14 años en su labor como entrenadores de baloncesto. Se realiza una sistematización de los fundamentos teóricos que sustentan la preparación táctica en el baloncesto y se elabora la estrategia, lo que permitirá elevar la preparación de estos profesionales, contribuyendo a la adquisición de habilidades pedagógicas-profesionales

Adaptive Vectorial Filter for Grid Synchronization of Power Converters Under Unbalanced and/or Distorted Grid Conditions

This paper presents a new synchronization scheme for detecting multiple positive-/negative-sequence frequency harmonics in three-phase systems for grid-connected power converters. The proposed technique is called MAVF-FLL because it is based on the use of multiple adaptive vectorial filters (AVFs) working together inside a harmonic decoupling network, resting on a frequency-locked loop (FLL) which makes the system frequency adaptive. The method uses the vectorial properties of the three-phase input signal in the αβ reference frame in order to obtain the different harmonic components. The MAVF-FLL is fully designed and analyzed, addressing the tuning procedure in order to obtain the desired and predefined performance. The proposed algorithm is evaluated by both simulation and experimental results, demonstrating its ability to perform as required for detecting different harmonic components under a highly unbalanced and distorted input grid voltage

Catalytic production of jet fuels from biomass

Concerns about depleting fossil fuels and global warming e ects are pushing our society to search for new renewable sources of energy with the potential to substitute coal, natural gas, and petroleum. In this sense, biomass, the only renewable source of carbon available on Earth, is the perfect replacement for petroleum in producing renewable fuels. The aviation sector is responsible for a significant fraction of greenhouse gas emissions, and two billion barrels of petroleum are being consumed annually to produce the jet fuels required to transport people and goods around the world. Governments are pushing directives to replace fossil fuel-derived jet fuels with those derived from biomass. The present mini review is aimed to summarize the main technologies available today for converting biomass into liquid hydrocarbon fuels with a molecular weight and structure suitable for being used as aviation fuels. Particular emphasis will be placed on those routes involving heterogeneous catalysts

«A Baptism of Fire»: Towards a Practical Hybrid Approach for the Lexicographic Indexation of Phraseological Units with Religious Lexical Components in English and Spanish

Traditionally, researchers have had a particular interest in the study of the relationship between phraseology and lexicography [e.g., Alonso Ramos (2006); Mellado Blanco (2008); Buendía Castro and Faber (2015); Paquot (2015); Nuccorini (2020)] to the point of having labeled it a «scientific marriage» (Leroyer 2006). In addition, scholars have been increasingly interested in the semantic analysis of phraseological units (henceforth PUs) [e.g., Grčić Simeunović and de Santiago (2016) and Torijano and Recio (2019)]. Among the problems that these and several other studies have pointed out, there is the recurrent reference to inaccuracy and difficulty in indexing PUs in lexicographic resources. Although some scholars consider onomasiological approaches as an interesting starting point [e.g., Bosque (2017) and Siepmann (2008)], a systematic methodology in phraseology that includes both the semantical analysis of the entries and their indexation is still needed./nWe intend to address that need here through the analysis of 242 idioms (199 in Spanish and 43 in English) extracted from a 21,045-idiom database that was compiled from two phraseological dictionaries: the Diccionario fraseológico documentado del español actual (henceforth DFDEA) (Seco, Andrés et al., 2004), and the Collins COBUILD Dictionary of Idioms (henceforth CCDOI) (Sinclair and Moon 1997). The criteria employed to select the resulting analysis units were: (i) they had to include at least one lexical component related to religion, and (ii) the idiom had to be nominal or verbal. The religious component was identified semi-automatically by using the UCREL's Semantic Analysis System (USAS) (Archer et al., 2002)./nThe contributions of this paper are as follows: (i) it presents a lexicographic analysis of the macrostructure and microstructure of the two phraseological resources previously mentioned, (ii) it offers a model of semantic analysis for PUs with religion-related components, (iii) it proposes an alternative indexation method of PUs in lexicographic resources involving semasiological and onomasiological approaches; and finally, (iv) it shows a systematic way to use semantic and pragmatic information in order to create semantic entries for PUs./nIn conclusion, by closely examining said set of phraseological entries, this study sheds light on the semantic composition of Pus. It also suggests a systematic hybrid approach for their lexicographic indexation in English and Spanish.Tradicionalmente, los investigadores han demostrado un particular interés por el estudio de la relación entre fraseología y lexicografía [p. ej. Alonso Ramos (2006); Mellado Blanco (2008); Buendía Castro y Faber (2015); Paquot (2015); Nuccorini (2020)] hasta el punto de denominarlo «matrimonio científico» (Leroyer 2006). De igual manera, los académicos se han interesado de manera creciente por el análisis semántico de las unidades fraseológicas (en nuestro texto, PUs, por sus siglas en inglés) [e.g., Grčić Simeunović y de Santiago (2016) y Torijano y Recio (2019)]. Entre los problemas que estos y otros estudios han señalado se encuentra la recurrente referencia a la inexactitud y la dificultad para indexar las PUs en los recursos lexicográficos. Aunque algunos investigadores consideran los enfoques onomasiológicos como un interesante punto de partida [e.g., Bosque (2017) y Siepmann (2008)], sigue siendo necesario establecer una metodología sistemática respecto a la fraseología que incluya tanto el análisis semántico de las entradas como su indexación./nNos proponemos abordar esta necesidad analizando 242 modismos (199 en español y 43 en inglés) extraídos de una base de datos con 21.045 modismos que ha sido compilada a partir de dos diccionarios fraseológicos: el Diccionario fraseológico documentado del español actual (en adelante DFDEA) (Seco, Andrés et al., 2004), y el Collins COBUILD Dictionary of Idioms (en adelante CCDOI) (Sinclair y Moon 1997). Los criterios empleados para seleccionar las unidades resultantes con vistas a su análisis han sido: (i) debían incluir al menos un componente léxico relacionado con la religión, y (ii) el modismo tenía que ser nominal o verbal. El componente religioso fue identificado de manera semi-automática utilizando el UCREL's Semantic Analysis System (USAS) (Archer et al., 2002)./nLas aportaciones de este artículo son las siguientes: (i) presenta un análisis lexicográfico de la macroestructura y la microestructura de los dos recursos fraseológicos antes mencionados, (ii) ofrece un modelo de análisis semántico para las PUs con componentes relacionados con la religión, (iii) propone un método de indexación alternativa de las PUs en recursos lexicográficos que implican enfoques semasiológicos y onomasiológicos; y finalmente, (iv) propone una manera sistemática de utilizar la información semántica y pragmática para crear entradas semánticas para las PUs./nEn conclusión, al examinar dicha serie de entradas fraseológicas, este estudio arroja luz sobre la composición semántica de las PUs. También sugiere un enfoque híbrido sistemático para su indexación lexicográfica en inglés y español

Electrochemical reduction of CO2: overcoming chemical inertness at ambient conditions

Electroreduction allows for the transformation of a chemically inert molecule such as CO2 into a wide variety of useful carbon products. Unlike other approaches operating at higher temperatures, electrochemical reduction holds great promise since it achieves reduction under ambient conditions, thereby providing more control over the reaction selectivity. By controlling basic parameters such as the potential and the composition of the electrode, CO2 can be transformed into a variety of products including carbon monoxide, syngas (CO/H2), methane, and methanol. This reduction process takes place without external hydrogen, since water can be used as a source of both electrons and protons. Furthermore, this technology, when combined with renewable wind- or solar-derived electricity, has the potential to serve as a storage system for excess electricity. Despite these advantages, a number of challenges need to be overcome before reaching commercialization. New (and cheaper) electrocatalyst formulations with high faradaic selectivities are required. Impressive progress has been made on carbon-doped materials, which, in certain cases, have outperformed expensive noble metal-based materials. Research is also needed on new electrochemical reactor configurations able to overcome kinetic/mass transport limitations, which are crucial to reduce overpotentials. Fine control over the nature of the active sites and the reaction conditions is important to avoid parasitic reactions such as the hydrogen evolution reaction (HER), and therefore increases the faradaic e ciency towards the desired products

Recent advances in the electroreduction of CO2 over heteroatom-doped carbon materials

Ever-growing anthropogenic activity has increased global energy demands, resulting in growing concentrations of greenhouse gases such as CO2 in the atmosphere. The electroreduction of CO2 has been proposed as a potential solution for reducing anthropogenic CO2 emissions. Despite the promising results obtained so far, some limitations hinder large-scale applications, especially those associated with the activity and selectivity of electrocatalysts. A good number of metal catalysts have been studied to overcome this limitation, but the high cost and low earth abundance of some of these materials are important barriers. In this sense, carbon materials doped with heteroatoms such as N, B, S, and F have been proposed as cheaper and widely available alternatives to metal catalysts. This review summarizes the latest advances in the utilization of carbon-doped materials for the electroreduction of CO2, with a particular emphasis on the synthesis procedures and the electrochemical performance of the resulting materials

Influencia del CO2 alimentado en la corriente de combustible en pilas de combustible tipo PEM de baja y alta temperatura

De entre todas las impurezas que pueden existir en el combustible alimentado a una PEMFC, el estudio de la influencia del C02 es de gran interés debido a las altas concentraciones que del mismo pueden estar presentes en una corriente de reformado, así como por ser uno de los contaminantes menos estudiados en la actualidad. La presencia de este contaminante en la corriente de H2 que es alimentada al ánodo produce pérdidas de rendimiento que, aunque no son tan elevadas como las obtenidas por la presencia de CO, no deben ser despreciadas El objetivo central de la presente tesis es profundizar y avanzar en el estado del conocimiento del efecto que produce la presencia de C02 en el combustible alimentado a pilas de combustible tipo PEM de baja y alta temperatura. Mediante el mismo, se discutirá la posibilidad de la existencia de un proceso de contaminación del catalizador además del efecto dilución causado inevitablemente por la presencia de C02. Para alcanzar dicho objetivo, la tesis se divide en los siguientes objetivos secundarios: 1. Estudiar el efecto producido por la presencia de diferentes concentraciones de C02 en el combustible alimentado a pilas tipo PEM de baja temperatura (LT PEMFCs) y alta temperatura (HT PEMFCs). 2. Determinar el papel que juega la densidad de corriente en el proceso de contaminación por C02. 3. Evaluar la influencia de la temperatura de operación en el impacto negativo producido por el C02 en LT PEMFCs y HT PEMFCs. 4. Analizar cómo afecta la humedad relativa al proceso de electro oxidación del CO en LT PEMFCs. 5. Investigar la influencia del catalizador en el impacto originado por la presencia de C02 en LT PEMFCs. 6. Estudiar diferentes métodos de regeneración del catalizador y aportar evidencias de la posibilidad de la existencia de un proceso de contaminación derivado de la presencia de C02 en el combustible. 7. Desarrollar una metodología de ensayos en pilas de combustible tipo PEM, que permita normalizar el desarrollo de las curvas de polarización en aquellos estudios en los que CO y/o C02 están presentes en el combustible alimentado al sistema. Los resultados sugieren que las pérdidas de rendimiento son mayores que si sólo existiera un efecto dilución debido al C02 debido a la producción de CO a partir de la reacción “Reverse Water Gas Shift” (RWGS). Los resultados se muestran a partir de los sobrepotenciales calculados. A su vez, se muestra el análisis de los diferentes parámetros de operación anteriormente mencionados. Finalmente, se desarrolla una metodología de ensayos que permite estudiar el efecto ejercido por contaminantes que presentan una naturaleza acumulativa con el tiempo, como pueden ser CO y C02.Among all the impurities, the study of the influence of C02 on the performance of a Polymer Electrolyte Membrane Fuel Cells (PEMFC) is of considerable interest due to the high concentration of this contaminant in a typical reformate mix. The presence of C02 in the fuel can produce performance losses that cannot be underestimated. An experimental investigation of the performance and contamination of Low and High Temperature PEMFCs operating with different concentrations of C02 at the anode inlet is presented. An analysis of different operating parameters (current density, temperature, relative humidity, catalyst composition and operating time) influence in the contamination process for both low and high temperature operation range are investigated in this work. To reach the main objective, the thesis is divided in the next secondary objectives: 1. Study the effect of different concentrations of H2/C02 mixtures at Low and High Temperature PEMFCs. 2. Researching the current density influence into the contamination process. 3. Evaluate the temperature effect of temperature which is closely related with the ratio “CO production/CO electro- oxidation”. 4. Study the effect of relative humidity in the CO electro-oxidation for LT PEMFCs. 5. Change the composition of catalyst in order to evaluate the impact in the contamination process for LT PEMFCs. 6. Study two different regeneration methods to recover the contaminated electrode, in order to recover initial performance. 7. Develop a new and versatile method to study the effect of contaminants which show an accumulative behavior with time. The results show that the performance loss is larger than expected if only a dilution effect were considered, so that a real contamination process occurs in the cell when C02 is fed to the anode, due to the RWGS reaction. This contamination effect is analysed and quantified by comparing the polarization curves of the contaminated cell with the ones corresponding to the cell operating with pure hydrogen. The oveipotentials for different operating parameters are presented and discussed for both types of fuel cells. Two different regeneration processes (anode feeding with pure H2 and with air) are also presented and discussed. The analysis of the effectiveness of each regeneration strategy also supports that CO produced via the RWGS reaction is adsorbed onto the catalyst

Análisis de la Identidad Laboral y el sin Sentido en Relación al Trabajo Tercerizado

Labor identity (LI) is a fundamental aspect of the worker. Without it, we are prone to generate nonsense for our work. Labor Outsourcing (LO) is a form of work that encourages the loss of LI and it has as a consequence on the nonsense of work (NW). The aim of this research is to investigate the correlation between LI and loss of consciousness in the LO context. To address this research, a quantitative research was conducted. A total sample of 55 people, composed of men and women between 25 and 56 years old, was used. Respondents were working on the outsourcing scheme in the personnel supply modality. The instrument that was applied was based on individual elaboration. Findings on the basis of NW and LI show high positive rates. Based on this, we can say that, despite the fact that workers live this precarious modality of work, they are motivated. However, we found that this absence of NW and presumed LI as a function of LO, is actually an apparent factor. This is due to the key items I2, SS3, T1 and T5 that has helped us to find the necessary support to affirm the existence of an aspirational LI feeling that generates the meaning of the work. Finally, we conclude that LO is perceived by the sample as a possible means to be directly employed by the primary organization of work

International Environmental Conventions and the civil society: a social network analysis in Spain

Las Convenciones Internacionales de Cambio Climático, Diversidad Biológica y Desertificación constituyen uno de los pilares para la gestión ambiental global. Se han analizado las redes sociales entre 47 ONGs españolas implicadas en la sensibilización sobre estas tres grandes convenciones. Se han identificado asimismo las ONGs con mayor actividad de comunicación y de intermediación en la red. Los resultados muestran que la Convención sobre Cambio Climático es la que cuenta con un mayor nivel de participación entre el conjunto de ONGs de la muestra, sin embargo, las organizaciones conservacionistas participan con mayor frecuencia en la Convención de Biodiversidad. La red social analizada sigue un patrón de "centro-periferia" con una baja densidad de vínculos sociales. Este estudio muestra la importancia de promover la cooperación entre las ONGs, especialmente entre las de conservación y las de desarrollo, para la creación de nuevos vínculos y así potenciar la capacidad de incidir en las convenciones y de influir en la sociedad civil española.The International Conventions on Climate Change, Biological Diversity and Desertification are one of the pillars for global environmental management. We analyzed the social networks of 47 Spanish NGOs involved in the promotion and awareness of these conventions. Furthermore we identified the NGOs with the highest levels of communication and interaction activity within the network. The results reveal that the highest levels of participation are in relation to the Climate Change Convention. However, conservation organizations have higher degree of participation in the Biodiversity Convention. The social networks analyzed follow a pattern of "core-periphery" with a low density of social ties. This study highlights the importance of promoting cooperation between the NGOs, especially among those involved in conservation and development, in order to establish new ties and thereby enhance the ability to affect the conventions and influence Spanish civil society