Impedance Spectroscopy Analysis of a Thermo-Electrochemical Cell Under Operating Conditions

Proceedings from the 2022 International Workshop on Impedance Spectroscopy (IWIS), Chemnitz, Germany, 2022.Low-grade (<200°C) heat is an abundant and available energy not generally exploited. In this regard, the so-called thermo-electrochemical cells have become a valid opportunity to harvest this ubiquitous source of heat. They are capable to convert heat into electricity by means of the temperature-redox potential dependency of a redox couple. In fact, they present Seebeck coefficient values in order of mV/K, much higher than solid-state thermoelectrics. In this work, a system formed by two Pt electrodes in contact with a 0.4 M ferro/ferricyanide aqueous solution has been studied by means of impedance spectroscopy under operating conditions (ΔT=40 K). The main processes which govern the performance of the system have been identified, which lead to different resistances: (i) electrolyte ionic resistance, (ii) charge transfer resistance and (iii) mass transfer resistance. It was also demonstrated that the current-voltage characteristics of the device can be obtained knowing the open-circuit potential and performing a single impedance spectroscopy measurement, which determines the device dc resistance. This method can save a significant amount of time in many cases

Dynamic Performance of a Mechanical Vapor Compression (MVC) Desalination System

This paper presents a numerical model to analyze the thermal and fluid dynamic behavior of a mechanical vapour compression MVC desalination system. The MVC desalination method is an evaporation and condensation process that occurs at low pressure, which requires a compression work to increase the saturation temperature of the vapor. The compressed vapor is condensed and its latent heat is transferred to the feed seawater. The MVC desalination is used at low and medium scale in comparison with other techniques such as: multistage flash desalination (MSF) or reverse osmosis (RO). The MVC desalination unit studied in this paper uses renewable energy to supply the electricity required by the different devices that make up the unit. The reason to use renewable energy is that the MVC desalination system has been though to work in remote places, where an electric grid is not available. However, using renewable energy means variability in the supply power. This variability should be well defined to avoid damage and establish secure partial working operation of the MVC desalination system. The transient and steady-state behaviors of the desalination system are evaluated taking into account the variability of the renewable energy sources (solar and wind energy). The MVC desalination system has been divided in three different subsystems, following the strategy proposed by Mazini (2014). The first subsystem is the evaporator and condenser, in which the evaporation and distillation processes are performed. The second is the vacuum and deareation subsystem, where the low pressure is achieved and non-condensed gas (Oxygen) is stripped. The last subsystem is the mechanical compressor, which is modeled to know its energetic requirement in function of the desalination performance and the climatic conditions. The mathematical formulation of the evaporator/condenser and vacuum subsystem is based on mass, energy and salt balance conservation equations. Whilst the compressor model is based on the root blower laws, in which the volumetric flow, velocity, power and the displacement by revolution values are related. The group of equations is solved by means of the in-house object-oriented tool called NEST, which is capable to link and solve different elements that making up a system (Damle, et. al., 2011). The MVC desalination system that is presented in this paper has different components: an evaporator/condenser, a compressor, a deareator, two heat exchangers and a group of pumps. Although in this numerical platform each component is an object, the whole system resolution is carried out iteratively for solving all its components and transferring the appropriated information between them. A scalability study has been carried out to find the relation between the variability of the renewable energy sources and the capacity of the desalination system (distilled water production). The influence of the feed seawater conditions is also analyzed on the system performance

Session B9: Influence of Biometric Parameters, Flow Condition and Water Temperature on Iberian Fish Sprinting Behavior: Volitionally Swimming Performance

Abstract: Knowing the swimming ability of fish is important to detect movement limitations through hydraulic structures: fish passes weirs and slots, gauging stations, culverts, bridges foundations and other. All these obstacles are collectively referred to velocity barriers . Fish behavior will determine the passage of these structures through combination of fish swimming performance and motivation. Once the fish decides to enter the barrier, must swim faster than the speed of the flow to advance. Thus, the swimming performance depends on the fish speed and fatigue time. To estimate these values, we experimented in an open channel flow with fish samples of different size, swimming volitionally against several high-velocity flows and water temperature range. The movement of fish was controlled by PIT telemetry systems and video record. The information obtained (fish speed, ascend time and distance traveled) was processed using survival analysis techniques and the results can be applied to practical problem solving velocity barriers. We have worked with two species of Iberian fish: Iberian barbel (Luciobarbus bocagei) and Northern straight-mouth nase (Pseudochondrostoma duriense). The biometrics parameters, flow velocity and water temperature have a significant influence in fish behavior. Endurance and swimming ability of these species do not differ greatly between them and is much higher than the values which are obtained using other methods as respirometers. The results challenge established fish passage guidelines, suggesting that in some cases these species are capable of passing much higher velocities than was previously believed

Comparative study of the combustion, pyrolysis and gasification processes of Leucaena leucocephala: Kinetics and gases obtained

Leucaena leucocephala is a fast-growing leguminous biomass with great energetical and valueadded chemical compounds potential (saccharides, biogas, bio-oil, etc.). Using the thermogravimetric and derivative thermogravimetric curves, the different trends followed by L. leucocephala during pyrolysis, 0.25 equivalence ratio (ER) of gasification, 0.50 equivalence ratio of gasification and combustion were analyzed, and the activation energies were obtained by Distributed Activation Energy Model (DAEM) method. Gas samples were collected through adsorption tubes during the gasification at 0.25 ER and 0.50 ER to observe the distribution of the main chemical products in this process by gas chromatography/mass spectrometry and were compared with pyrolysis products. It was found that small amounts of oxygen have changes in the kinetics of the process, leading to significant decreases in the activation energy at the beginning of the degradation of components such as cellulose (from 170 to 135 kJ mol-1 at 0.25 conversion at 0.50 ER gasification). The activation energy of lignin disintegration was also reduced (342 kJ mol-1), assimilating the beginnings of gasification processes such as the Boudouard reaction. 0.50 ER gasification is potentially an interesting process to obtain quality bio-oil, since a large amount of hexane is detected (44.96%), and value-added oxygenated intermediates such as alcohols and glycols. Gasification at 0.25 ER, on the other hand, is much more similar to pyrolysis, obtaining a wide variety of short-chain compounds resulting from the disintegration of the main lignocellulosic components, especially ketones such as 1-hydroxypropan-2-one (19.48%), and notable amount of furans and anhydrosugars like d-allose (5.50%).This study was supported by the Ministry of Economy and Competitiveness (Spain), as well as by the National Research Program Oriented to the Challenges of Society (Project PID2020-112875RB-C21 funded by MCIN/AEI 10.13039/501100011033, t)he Ministry of Innovation, Science and Business of the Government of the Junta of Andalusia (Spain), the Operative Program is framed within FEDER Andalusia 2014–2020 with Project number UHU-125540, and the CEPSA Foundation Chair. Funding for open access charge: Universidad de Huelva / CBUA

Homework encouragement by means of peer reviewed activities and global group tutorials

Se parte de la detección de una serie de carencias en la adquisición de conocimientos en la asignatura Motores y Máquinas de 2.º curso del Grado en Ingeniería Agroalimentaria y del Medio Rural. Para dirigir y motivar al alumnado de cara a la superación de la asignatura se organizaron dos prácticas fuera del aula (P2 y P3), de la misma naturaleza que los tres tipos de ejercicios de examen (P1, P2 y P3). La corrección de las prácticas se hizo mediante evaluación por pares y posterior revisión del profesorado. La realización de las dos prácticas tuvo un seguimiento desigual, con una tasa de evaluación de 33 y 22 % respectivamente, mientras que la tasa de éxito fue muy elevada, 87 y 97 %. En cuanto a los resultados del examen, la tasa de evaluación fue del 59 y 55 %, y la tasa de éxito del 50 y 36 %, inferior a la registrada en las prácticas. Sin embargo la tasa de rendimiento fue similar entre el examen (30 - 20 %) y las prácticas (29 y 12 %). Los resultados de los exámenes del curso 2016/17 fueron mejores que en los exámenes del curso 2015/16, por lo tanto se ha cumplido el objetivo de mejorar el porcentaje de alumnos que superan la asignatura, mejorando o manteniendo el rendimiento. Por último, la tasa de evaluación no mostró un resultado satisfactorio en las prácticas, por lo que se hace necesario incidir entre el alumnado en la importancia de estas actividades.Firstly, it has been detected some deficiencies in the acquisition of knowledge for the subject “Motores y Máquinas” corresponding to the 2nd year of the Degree in Agri-food Engineering and Rural Environment. Two homework practices (P2 and P3), similar to the three types of exam exercises (P1, P2 and P3) were organized to tutorize and motivate students in order to pass the subject. Practices correction was done through peer evaluation and subsequent revision of the teaching staff. The performance of the two practices was unevenly followed, with an evaluation rate of 33 and 22% respectively, while the success rate was very high, 87 and 97%. Regarding the results of the examination, the evaluation rate was 59 and 55% and the success rate was of 50 and 36% for P2 and P3 respectively, lower than that recorded in the practices. However, the rate of performance was similar between exam (30 - 20%) and practices (29 and 12%). The results of the 2016/17 exams were better than in the examinations of the 2015/16 course, therefore the objective of improving the percentage of students who pass the subject, improving or maintaining the performance has been accomplish. Finally, the evaluation rate did not show a satisfactory result for the practices, for this reason, it is necessary to persuade the students to the importance of these activities

TRIBUNAL ARBITRAL DE CARACOL TELEVISIÓN S.A. VS. FEDERACIÓN COLOMBIANA DE FÚTBOL

1570

Olive Crown Porosity Measurement Based on Radiation Transmittance: An Assessment of Pruning Effect

Crown porosity influences radiation interception, air movement through the fruit orchard, spray penetration, and harvesting operation in fruit crops. The aim of the present study was to develop an accurate and reliable methodology based on transmitted radiation measurements to assess the porosity of traditional olive trees under different pruning treatments. Transmitted radiation was employed as an indirect method to measure crown porosity in two olive orchards of the Picual and Hojiblanca cultivars. Additionally, three different pruning treatments were considered to determine if the pruning system influences crown porosity. This study evaluated the accuracy and repeatability of four algorithms in measuring crown porosity under different solar zenith angles. From a 14 to 30 solar zenith angle, the selected algorithm produced an absolute error of less than 5% and a repeatability higher than 0.9. The described method and selected algorithm proved satisfactory in field results, making it possible to measure crown porosity at different solar zenith angles. However, pruning fresh weight did not show any relationship with crown porosity due to the great differences between removed branches. A robust and accurate algorithm was selected for crown porosity measurements in traditional olive trees, making it possible to discern between different pruning treatments

Mechanical canopy and trunk shaking for the harvesting mechanization of table olive orchards

Table olive harvesting is highly dependent on manual labour and may jeopardize the crop benefit. The introduction of a mechanical harvest system requires a global evaluation of the whole process. A trunk shaker along with shaker combs and a continuous canopy shaker harvester have been tested in two orchards with different tree training and layout to determine their feasibility to mechanical harvesting in table olives. For that purpose, several parameters have been evaluated. Canopy shaker required adapted orchard layout and hedge of canopies for reaching an acceptable harvesting efficiency about 80% and trunk shaker performed a higher efficiency of more than 95% but depended highly on labour. Both systems had a high field capacity about 0.15 ha h-1 but low for the trunk shaker considering the people (0.01 ha h-1 person-1). The vibration pattern that applied on branches was totally different although the quantitative tree damages were no significative different. There were no significant differences in fruit bruising between both systems, but there were between the different sampling points, mainly in the detachment. The fruit bruising index of the remaining fruit on canopy suggests that it is possible to perform a second harvest. Both mechanical systems are suitable for table olive harvesting whilst improving the efficiency of manual systems with bearable damages, but each one has pros and cons that must be considered bearing in mind that require an adaptation of the orchard where there are applied. Highlights Table olives mechanization is possible by integrating with the fruit liquid store. Trunk shaker performed high efficiency in adapted orchards but depended on labour. Canopy shakers require the adaption of orchard and machine for commercial purposes. There were no differences in detached fruit bruising between both mechanical systems. The bruising index of the remaining fruit on trees suggest second harvesting pass.Table olive harvesting is highly dependent on manual labour and may jeopardize the crop benefit. The introduction of a mechanical harvest system requires a global evaluation of the whole process. A trunk shaker along with shaker combs and a continuous canopy shaker harvester have been tested in two orchards with different tree training and layout to determine their feasibility to mechanical harvesting in table olives. For that purpose, several parameters have been evaluated. Canopy shaker required adapted orchard layout and hedge of canopies for reaching an acceptable harvesting efficiency about 80% and trunk shaker performed a higher efficiency of more than 95% but depended highly on labour. Both systems had a high field capacity about 0.15 ha h-1 but low for the trunk shaker considering the people (0.01 ha h-1 person-1). The vibration pattern that applied on branches was totally different although the quantitative tree damages were no significative different. There were no significant differences in fruit bruising between both systems, but there were between the different sampling points, mainly in the detachment. The fruit bruising index of the remaining fruit on canopy suggests that it is possible to perform a second harvest. Both mechanical systems are suitable for table olive harvesting whilst improving the efficiency of manual systems with bearable damages, but each one has pros and cons that must be considered bearing in mind that require an adaptation of the orchard where there are applied. Highlights Table olives mechanization is possible by integrating with the fruit liquid store. Trunk shaker performed high efficiency in adapted orchards but depended on labour. Canopy shakers require the adaption of orchard and machine for commercial purposes. There were no differences in detached fruit bruising between both mechanical systems. The bruising index of the remaining fruit on trees suggest second harvesting pass

Trabajo del sujeto privado de la libertad en el contexto penitenciario y la incidencia socio-económica en su familia

La presente investigación tiene como objetivo principal, determinar cómo el trabajo de los Sujetos Privados de la Libertad (SPL) en los talleres de maderas pertenecientes al ámbito penitenciario, incide en las condiciones socio-económicas de sus familias, resaltando el emprendimiento social como vía para la sostenibilidad y sustentabilidad familiar. Además, se pretende dar respuesta a las preguntas planteadas en la presente investigación, la primera enfocada en ¿cómo el trabajo de los Sujetos Privados de la Libertad en los talleres de maderas ubicados en el Complejo Carcelario y Penitenciario Metropolitano de Bogotá- COMEB (Picota) incide en las condiciones socio-económicas de sus familias?, en segundo lugar se busca responder a los aportes que se pueden establecer desde el emprendimiento social para la sostenibilidad y sustentabilidad de los Sujetos Privados de la Libertad y sus familias; se responden a través de tres momentos principales: la reflexión, la crítica y la propuesta, enfocado en una mirada prospectiva e inductiva hacia el desarrollo humano

Laboratorio remoto eLab3D: un entorno innovador para el aprendizaje de competencias prácticas en electrónica

Este artículo muestra la utilización de las nuevas tecnologías al servicio del aprendizaje de competencias prácticas en electrónica, siendo un ejemplo de adaptación de los recursos educativos a diferentes contextos y necesidades. Se trata de un laboratorio remoto en el que la adecuada complementación de un hardware configurable y un software de última generación permite al estudiante realizar prácticas de electrónica y diseño de circuitos en un mundo virtual 3D. El usuario dispone de un avatar e interacciona con réplicas virtuales de instrumentos, placas de circuitos, componentes o cables de forma muy similar a como se opera en un laboratorio presencial. Pero lo realmente destacable es que el usuario manipula instrumentación y circuitos que están ubicados en un laboratorio real. Todo ello se ha conseguido con un sistema escalable y de bajo coste. Finalizado el diseño y desarrollo de la plataforma se han realizado las primeras pruebas con estudiantes, profesores y profesionales para valorar su percepción respecto al uso de eLab3D, obteniéndose unos resultados muy positivos