Análisis y simulación de sistemas trifásicos con transformadores conexión D-Y

El presente proyecto se enfoca en proveer un análisis a fondo de un sistema de transformadores trifásicos conectados en Delta – Estrella, sus características, aplicaciones, ventajas y desventajas, además de su comportamiento frente a diferentes tipos de cargas. Para esto se realizará una adquisición de datos de los parámetros del circuito y mediante una aplicación software se graficará los diagramas fasoriales y triángulos de potencia. Para culminar el análisis se realizarán los cálculos teóricos y se compararán con los datos obtenidos previamente.The present project focuses on providing a thorough analysis of a three-phase transformer system connected in D - Y, its characteristics, applications, advantages and disadvantages, in addition to its behavior against different types of loads. For this, a data acquisition of the circuit parameters will be carried out and by a software application, the phasor diagrams and power triangles will be plotted. To complete the analysis, theoretical calculations will be performed and compared with previously obtained data

Quantum Dot-Sensitized Solar Cells Based on Directly Adsorbed Zinc Copper Indium Sulfide Colloids

Heavy metal-based quantum dots (QDs) have demonstrated to behave as efficient sensitizers in QD-sensitized solar cells (QDSSCs), as attested by the countless works and encouraging efficiencies reported so far. However, their intrinsic toxicity has arisen as a major issue for the prospects of commercialization. Here, we examine the potential of environmentally friendly zinc copper indium sulfide (ZCIS) QDs for the fabrication of liquid-junction QDSSCs by means of photoelectrochemical measurements. A straightforward approach to directly adsorb ZCIS QDs on TiO2 from a colloidal dispersion is presented. Incident photon-to-current efficiency (IPCE) spectra of sensitized photoanodes show a marked dependence on the adsorption time, with longer times leading to poorer performances. Cyclic voltammograms point to a blockage of the channels of the mesoporous TiO2 film by the agglomeration of QDs as the main reason for the decrease in efficiency. Photoanodes were also submitted to the ZnS treatment. Its effects on electron recombination with the electrolyte are analyzed through electrochemical impedance spectroscopy and photopotential measurements. The corresponding results bring out the role of the ZnS coating as a barrier layer preventing electron leakage toward the electrolyte, as argued in other QD-sensitized systems. The beneficial effect of the ZnS coating is ultimately reflected on the power conversion efficiency of complete devices, reaching values of 2 %. In a more general vein, through these findings, we aim to call the attention to the potentiality of this quaternary alloy, virtually unexplored as a light harvester for sensitized devices.N.G. is grateful to the Spanish Ministry of Education for the award of an FPU grant. The group acknowledges support of the Spanish Ministry of Economy and Competitiveness through projects HOPE CSD2007-00007 (Consolider Ingenio 2010) and MAT2012-37676 (Fondos FEDER)

Una revisión sistemática sobre los aportes del compromiso organizacional al desarrollo empresarial

La presente investigación tiene como objetivo determinar los aportes que brinda el Compromiso Organizacional al Desarrollo Empresarial según los artículos de investigación publicados en ScienceDirect entre los años 2018 y 2021; con la metodología de investigación de tipo teórica y de diseño Revisión Sistemática, con 9 artículos de investigación seleccionados como muestra. Para ello, se empleó como instrumento de recaudación de datos a la búsqueda booleana en la plataforma ScienceDirect, tomando en cuenta diversos criterios de inclusión y exclusión para la elección de investigaciones revisadas. Debido a ello, se puede afirmar que el nivel de compromiso organizacional de cada trabajador de una empresa se relaciona con el desarrollo de la compañía en función a sus objetivos y metas propuestas

Enfoque palinofacial a través del límite Cretácico - Paleógeno en la Isla Marambio (Seymour), Península Antártica

El presente estudio analiza el comportamiento de la materia orgánica palinológica a través del límite Cretácico-Paleógeno de la Isla Marambio (Seymour). El límite estudiado se encuentra en la sección superior de la Formación López de Bertodano y coincide con un horizonte glauconítico. Se analizaron quince muestras las cuales fueron agrupadas en cuatro palinofacies de acuerdo a la composición porcentual de la materia orgánica. La caracterización palinofacial es indicativa de un ambiente de depositación de plataforma marina proximal. La asociación de las palinofacies permitió discriminar la sección estudiada en tres intervalos menores relacionados a tres estadios en el nivel del mar. La integración de estos estadios resulta en una curva de nivel del mar hipotética que refleja un pulso transgresivo-regresivo menor, dentro de una tendencia regresiva general. La máxima profundidad de agua se sugiere cerca de un metro por debajo del límite K-P propuesto. La identificación palinofacial de este pulso es concordante con la idea de un evento transgresivo-regresivo lento y con ciclos internos. La preservación de la materia orgánica a través del límite K-P no sugiere un efecto local del hipotético evento catastrófico global. Considerando la monótona litología de la Formación López de Bertodano que dificulta el reconocimiento de discontinuidades, este trabajo abre la posibilidad de aplicar, en futuras investigaciones, modelos secuenciales basados en el reconocimiento de superficies de máxima inundación.This study analyzes the palynological organic matter behavior throughout the Cretaceous- Paleogene boundary in Marambio (Seymour) Island, Antarctic Peninsula. The boundary is located in the upper part of the López de Bertodano Formation, coinciding with a widespread glauconitic level. Fifteen samples were analyzed and associated with four palynofacies. Defined palynofacies indicate an inner shelf marine environment of sedimentation. The palynofacial assemblages permitted discriminating the studied section into three minor stratigraphical intervals related to three sea-level stages. The integration of these stages results in a hypothetical sea-level curve, which reflects a minor transgressive - regressive pulse into a general regressive trend. The maximun water depth is about 1 m below the postulated K/P boundary. Palinofacial recognition of this pulse supports the earlier idea of a slow transgressive-regressive event with minor internal transgressive-regressive cycles. Palynofacial data indicates preservation of the organic matter across the K-P boundary, and therefore do not suggest any local effect of the hypothetical global catastrophic K/P event. Considering the monotonous lithology of the López de Bertodano Formation that makes the recognition of unconformities difficult, this work opens the possibility of applying a sequence stratigraphic approach based on the recognition of maximum flooding surfaces for future investigations.Fil: Rodríguez Brisuela, Rafael. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Marenssi, Sergio Alfredo. Ministerio de Relaciones Exteriores, Comercio Interno y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Barreda, Viviana Dora. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Santillana, Sergio Nestor. Ministerio de Relaciones Exteriores, Comercio Interno y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino; Argentin

Effect of different compatibilizers on environmentally friendly composites from poly(lactic acid) and diatomaceous earth

[EN] Environmentally friendly composites from poly(lactic acid) (PLA) and diatomaceous earth (DE) were successfully manufactured by extrusion, followed by injection moulding. DE was used as a filler; several compatibilizer/coupling agents, namely (3-glycidyloxypropyl)trimethoxysilane, epoxy styrene acrylic oligomer and maleinized linseed oil, were used to improve polymer¿filler interactions. Mechanical characterization was carried out by standard tensile, impact and hardness tests while morphological characterization of the fractured surfaces was conducted by field emission scanning electron microscopy. The effect of DE was evaluated by differential scanning calorimetry and dynamic mechanical thermal behaviour. The results show that the addition of DE provides an improved tensile modulus and induces more brittle composites due to stress concentration phenomena. The addition of compatibilizers in PLA-DE positively contributes to improve ductile properties, thus leading to high environmental efficiency materials with balancedmechanical properties. Specifically, the compatibility improvement between the PLA and DE was good with maleinized linseed oil and contributed to improving the impact strength, which is a key factor in PLA-based composites due to the intrinsic brittleness of neat PLA.This research was supported by the Spanish Ministry of Economy and Competitiveness (MINECO) program number MAT2017-84909-C2-2-R. L. Quiles-Carrillo wants to thank GV for his FPI grant (ACIF/2016/182) and the MECD for his FPU grant (FPU15/03812).Agüero-Rodríguez, Á.; Quiles-Carrillo, L.; Jorda-Vilaplana, A.; Fenollar, O.; Montanes, N. (2019). Effect of different compatibilizers on environmentally friendly composites from poly(lactic acid) and diatomaceous earth. 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