Analysis of the effect of clock drifts on frequency regulation and power sharing in inverter-based islanded microgrids

© 2018 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes,creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.Local hardware clocks in physically distributed computation devices hardly ever agree because clocks drift apart and the drift can be different for each device. This paper analyses the effect that local clock drifts have in the parallel operation of voltage source inverters (VSIs) in islanded microgrids (MG). The state-of-the-art control policies for frequency regulation and active power sharing in VSIs-based MGs are reviewed and selected prototype policies are then re-formulated in terms of clock drifts. Next, steady-state properties for these policies are analyzed. For each of the policies, analytical expressions are developed to provide an exact quantification of the impact that drifts have on frequency and active power equilibrium points. In addition, a closed-loop model that accommodates all the policies is derived, and the stability of the equilibrium points is characterized in terms of the clock drifts. Finally, the implementation of the analyzed policies in a laboratory MG provides experimental results that confirm the theoretical analysis.Peer ReviewedPostprint (author's final draft

Chemical characterization of traditional varietal olive oils in East of Spain

The aim of this work has been to characterize the chemical composition of the eight most emblematic varietal olive oils from the West of the Mediterranean Sea. These were classified into two groups according to the International Olive Council (IOC norms): Sweet oils (Farga, Morruda and Serrana) which were compared with Arbequina as standard of the Spanish sweet oils; and bitter¿spicy oils (Alfafara, Blanqueta, and Villalonga) that were compared with Picual, considered as the standard of the bitter¿spicy olive oils. For the study, sampled trees were chosen in their geographically separated originating areas. They were cultivated in the traditional conditions. The variety of each sampled tree was previously identified by the International Union for the Protection of new Varieties for Plants (UPOV TG/99/4). We have attempted to find differences between these varieties based on their fatty acid and sterol components. Although our results of only the sterols in olive oils suggested that stigmasterol could allow the segregation of the varieties, our experience indicates that analysis of the main fatty acids (palmitic, oleic and linoleic), together with a PCA applied to all fatty acids and sterols, can be used to validate the varietal determinations with enough precision. In addition, α-tocopherol can be used as differentiator in bitter¿spicy oils

La cohesión-integración versus la fragmentación social desde una perspectiva relacional

Background of INCASI Project H2020-MSCA-RISE-2015 GA 691004. WP1: CompilationEl artículo analiza los conceptos de inclusión, cohesión e integración social versus exclusión y fragmentación social desde una perspectiva relacional. Dichos conceptos se contextualizan y articulan desde el marco teórico del capital social y se expresan operativamente mediante indicadores de análisis de redes sociales. En el plano empírico, se analiza la estructura de los indicadores relacionales y se observa su asociación con variables atributivas socio-demográficas. Los resultados obtenidos muestran que las personas entrevistadas que residen en entornos metropolitanos y que participan en el mercado de trabajo tienen redes personales menos cohesivas, aunque de la fragmentación de las redes personales no se pueden inferir directamente determinadas posiciones sociales, al menos sin considerar otros aspectos atributivos y contextuales.This paper analyses the concepts of inclusion, social cohesion and integration versus social exclusion and fragmentation from a relational perspective. These concepts are, first, contextualized and articulated within the theoretical framework of social capital and, second, operationalized as social network analysis measures. At the empirical level, the article identifies the structure of these relational measures and its association with socio-demographic variables. The analysis shows that (i) individuals living in metropolitan areas and participants in the labour market (employed and unemployed) have less cohesive networks, and that (ii) fragmentation of personal networks is not directly associated with particular social positions, at least without considering other contextual factors

La extensión del glaciarismo cuaternario en el Parque Nacional de Ordesa y Monte Perdido

The maximal extent reached by the glaciers in the Ordesa and Monte Perdido National Park during the young Pleistocene is discussed. The great height of the Monte Perdido massif allowed the existence of deep ice tongues that had their final area around 900 m a.s.l., except for the Escuaín and Pardina-Vióglaciers, that owing to the lower altitude and extent of their respective headwaters finished higher. The absence of frontal moraines obligates us to reconstruct such extent by means of lateral moraines and other deposits (fluvioglacial terraces, screes, alluvial fans). Likewise, other glacial deposits are cited, belonging to retreat phases. A phase of altitude glaciers, other of cirque glaciers and the Little Ice Age can be distinguished.Se revisa la extensión máxima alcanzada por los glaciares del Parque Nacional de Ordesa y monte perdido durante el pleistoceno reciente. La gran altitud del macizo de monte perdido permitió la existencia de potentes lenguas de hielo que tenían su zona terminal en torno a 900 m, excepto el glaciar de escuain y el de pardina-vio, que en razón de la menor altitud y extensión de sus respectivas cabeceras finalizaban muy por encima de ese limite. La ausencia de morrenas frontales obliga a reconstruir tal extensión por medio de morrenas laterales y otros depósitos (terrazas fluvioglaciares, brechas, conos de deyección). Se alude igualmente a otros depósitos glaciares correspondientes a fases de retracción, pudiendo distinguirse una fase de glaciares de altitud, otra de glaciares de circo y la pequeña edad del hielo

La extensión del glaciarismo cuaternario en el Parque Nacional de Ordesa y Monte Perdido

The maximal extent reached by the glaciers in the Ordesa and Monte Perdido National Park during the young Pleistocene is discussed. The great height of the Monte Perdido massif allowed the existence of deep ice tongues that had their final area around 900 m a.s.l., except for the Escuaín and Pardina-Vióglaciers, that owing to the lower altitude and extent of their respective headwaters finished higher. The absence of frontal moraines obligates us to reconstruct such extent by means of lateral moraines and other deposits (fluvioglacial terraces, screes, alluvial fans). Likewise, other glacial deposits are cited, belonging to retreat phases. A phase of altitude glaciers, other of cirque glaciers and the Little Ice Age can be distinguished.Se revisa la extensión máxima alcanzada por los glaciares del Parque Nacional de Ordesa y monte perdido durante el pleistoceno reciente. La gran altitud del macizo de monte perdido permitió la existencia de potentes lenguas de hielo que tenían su zona terminal en torno a 900 m, excepto el glaciar de escuain y el de pardina-vio, que en razón de la menor altitud y extensión de sus respectivas cabeceras finalizaban muy por encima de ese limite. La ausencia de morrenas frontales obliga a reconstruir tal extensión por medio de morrenas laterales y otros depósitos (terrazas fluvioglaciares, brechas, conos de deyección). Se alude igualmente a otros depósitos glaciares correspondientes a fases de retracción, pudiendo distinguirse una fase de glaciares de altitud, otra de glaciares de circo y la pequeña edad del hielo

Fusion of Sensor Data and Intelligence in FITS

Proceedings of: 16th International Conference on Information Fusion (FUSION 2013): Istambul, Turkey 9-12 July 2013.The design and implementation of fusion systems working in real conditions requires functional and performance specification, analysis of information input and contextual domain, and development of testing and validation tools. This paper presents a fusion system recently developed to operate with EW and ISR sensors on-board of patrol aircraft, which must be fused with information from other collaborative entities and intelligence in databases. The paper describes the overall organization of the system developed, modules and the data flow. The characterization of data sources and core algorithms for data alignment, uncertainty representation and fusion management are detailed and validated in realistic situations.This work was supported in part by Projects FITS-DFS (EADS/CASA), MEyC TEC2012-37832-C02-01, MEyC TEC2011-28626-C02-02 and CAM CONTEXTS (S2009/TIC-1485).Publicad

Large mass movements in relation to deglaciation in the Pyrenees

22 páginasPeer reviewe

Central Spanish Pyrenees: Glacial and periglacial landforms.

32 páginasPeer reviewe

Norfloxacin mineralization under light exposure using Sb-SnO2 ceramic anodes coated with BiFeO3 photocatalyst

[EN] Advanced Oxidation Processes have been proven to be an efficient way to remove organic pollutants from wastewaters. In this work, a ceramic electrode of Sb-SnO2 (BCE) with a layer of the photocatalytic material BiFeO3 (BFO-BCE), has been characterized electrochemically and further tested for norfloxacin photoelectrooxidation in the presence and absence of light. The electrode photoactivity was highly enhanced thanks to the presence of BiFeO3, as confirmed by Linear Sweep Voltammetry, chronoamperometry and potentiometry, and Electrochemical Impedance Spectroscopy. Additionally, working in galvanostatic mode, a high mineralization of norfloxacin was achieved after 240 min, reaching 62% at 25 mA cm 2 under light conditions. This value is comparatively higher than the 40% achieved with the BCE. The oxidation byproducts were followed by ionic chromatography and HPLC analysis, which also allowed us to propose an oxidation pathway of the norfloxacin molecule. Finally, some indicators of the reactor performance such as the Mineralization Current Efficiency and the specific energy consumption were analyzed, revealing that lower current densities (8.3 mA cm -2) led to higher current efficiencies, and that light improved both the current efficiency and energy consumption.The authors thank the financial support through the project RTI2018-101341-B-C21 funded by MCIN/AEI/10.13039/501100011033/ (Spain) and by FEDER A way of making Europe and AICO/2021/128 funded by Generalitat Valenciana.Domingo-Torner, C.; García Gabaldón, M.; Martí Calatayud, MC.; Mestre, S.; Pérez-Herranz, V. (2023). Norfloxacin mineralization under light exposure using Sb-SnO2 ceramic anodes coated with BiFeO3 photocatalyst. Chemosphere. 313. https://doi.org/10.1016/j.chemosphere.2022.13751831

Improving water quality does not guarantee fish health: Effects of ammonia pollution on the behaviour of wild-caught pre-exposed fish.

Ammonia is a pollutant frequently found in aquatic ecosystems. In fish, ammonia can cause physical damage, alter its behaviour, and even cause death. Exposure to ammonia also increases fish physiological stress, which can be measured through biomarkers. In this study, we analysed the effect of sublethal ammonia concentrations on the behaviour and the oxidative stress of Barbus meridionalis that had been pre-exposed to this compound in the wild. Wild-caught fish from a polluted site (pre-exposed fish) and from an unpolluted site (non-pre-exposed fish) were exposed, under experimental conditions, to total ammonia concentrations (TAN) of 0, 1, 5, and 8 mg/L. Swimming activity, feeding behaviour, and oxidative stress response based on biomarkers were analysed. Pre-exposed fish showed both an altered behaviour and an altered oxidative stress response in the control treatment (0 mg/L). Differences in swimming activity were also found as pre-exposed fish swam less. Lower feeding activity (voracity and satiety) and altered response to oxidative stress were also observed at 1 mg/L TAN. Biomarker results confirmed pre-exposed fish suffer from a reduction in their antioxidant defences and, hence, showed increased oxidative tissue damage. In summary, pre-exposed fish showed more sensitivity to ammonia exposure than fish from a pristine site