Efficient heuristic algorithms for location of charging stations in electric vehicle routing problems

Indexación: Scopus.This work has been partially supported by CONICYT FONDECYT by grant 11150370, FONDEF IT17M10012 and the “Grupo de Logística y Transporte” at the Universidad del Bío-Bío.. This support is gratefully acknowledged.Eco-responsible transportation contributes at making a difference for companies devoted to product delivery operations. Two specific problems related to operations are the location of charging stations and the routing of electric vehicles. The first one involves locating new facilities on potential sites to minimise an objective function related to fixed and operational opening costs. The other one, electric vehicle routing problem, involves the consolidation of an electric-type fleet in order to meet a particular demand and some guidelines to optimise costs. It is determined by the distance travelled, considering the limited autonomy of the fleet, and can be restored by recharging its battery. The literature provides several solutions for locating and routing problems and contemplates restrictions that are closer to reality. However, there is an evident lack of techniques that addresses both issues simultaneously. The present article offers four solution strategies for the location of charging stations and a heuristic solution for fleet routing. The best results were obtained by applying the location strategy at the site of the client (relaxation of the VRP) to address the routing problem, but it must be considered that there are no displacements towards the recharges. Of all the other three proposals, K-means showed the best performance when locating the charging stations at the centroid of the cluster. © 2012-2018. National Institute for R and D in Informatics.https://sic.ici.ro/wp-content/uploads/2018/03/Art.-8-Issue-1-2018-SIC.pd

A new, Gaia based, catalogue of blue straggler stars in open clusters

Blue straggler stars are exotic objects present in all stellar environments whose nature and formation channels are still partially unclear. They seem to be particularly abundant in open clusters (OCs), thus offering a unique chance to tackle these problems statistically.We aim to build up a new and homogeneous catalogue of blue straggler stars (BSS) in Galactic OCs using Gaia to provide a more solid assessment of the membership of these stars. We also aim to explore possible relationships of the straggler abundance with the parent cluster's structural and dynamical parameters. As a by-product, we also search for possible yellow straggler stars (YSS), which are believed to be stragglers in a more advanced evolution stage. We employed photometry, proper motions, and parallaxes extracted from Gaia DR2 for 408 Galactic star clusters and searched for stragglers within them after performing a careful membership analysis. The number of BBS emerging from our more stringent, selection criteria turns out to be significantly smaller than in previous versions of this catalogue. OCs are therefore not a preferable environment for these kinds of stars anymore. In addition, we found that BSS start to appear in clusters with ages larger than log(t) ~ 8.7 and are therefore absent in very young star clusters.The present catalogue supersedes the previous ones in several ways: membership assessment, number of stragglers found, and so forth. The new list includes 897 BSS and 77 YSS candidates in 408 OCs. We expect this catalogue to be the basis for a new round of studies of BSS and YSS.Comment: 9 pages, 4 figures, accepted for publication in A&A Journal on 22/02/202

Seven years of marine environmental changes monitoring at coastal OOCS stations (Catalan Sea, NW Mediterranean)

Since March 2009 up to the present (more than 7 years now), the Operational Observatory of the Catalan Sea (OOCS; http://www2.ceab.csic.es/ oceans/) remains a witness of persistent marine environmental changes. The OOCS has two fixed observation stations at the head of the Blanes Canyon (200 m depth, 41.66°N; 2.91°E) and at the Blanes bay (20 m depth, 41.67°N; 2.80°E) in the Catalan Sea, NW Mediterranean. At the canyon station, a multi-parametric buoy presently installed delivers high frequency (by 30 min) and multi-parametric oceanographic (i.e. salinity, temperature, chlorophyll, turbidity, as well as light intensity in the PAR range for the upper 50 m depth) and atmospheric (air temperature, relative humidity, wind speed and direction and PAR) data. Subsurface photos and videos by an IP high resolution fisheye camera attached to the buoy are also delivered at 4-hour basis. Data and multimedia are transmitted in near real time for public access, via combined GSM/GPRS and 3G connections. At both stations, CTD profiles and water samples (collected for nutrients and picoplankton analyses) are carried out on board a research vessel at fortnightly basis. Numerical simulations along with the time series of in-situ observations show inter-annual seasonality anomalies possibly linked to global environmental changes. The lower-atmosphere and upper-sea environmental time series data collected prove the occurrence of shifting patterns of heat and matter fluxes impacting pelagic and benthic organisms.Peer Reviewe

A super lithium-rich red-clump star in the open cluster Trumpler 5

Context. The existence of lithium-rich low-mass red giant stars still represents a challenge for stellar evolution models. Stellar clusters are privileged environments for this kind of investigation. Aims. To investigate the chemical abundance pattern of the old open cluster Trumpler\,5, we observed a sample of four red-clump stars with high-resolution optical spectrographs. One of them (#3416) reveals extremely strong lithium lines in its spectrum. Methods. One-dimensional, local thermodynamic equilibrium analysis was performed on the spectra of the observed stars. A 3D-NLTE analysis was performed to derive the lithium abundance of star #3416. Results. Star #3416 is super Li-rich with A(Li)=3.75\,dex. The lack of $^6$Li enrichment ($^6$Li/$^7$Li$<$2%), the low carbon isotopic ratio ($^{12}$C/$^{13}$C=14$\pm$3), and the lack of evidence for radial velocity variation or enhanced rotational velocity ($v\sin i = 2.8\,$\kms) all suggest that lithium production has occurred in this star through the Cameron & Fowler mechanism. Conclusions. We identified a super Li-rich core helium-burning, red-clump star in an open cluster. Internal production is the most likely cause of the observed enrichment. Given the expected short duration of a star's Li-rich phase, enrichment is likely to have occurred at the red clump or in the immediately preceding phases, namely during the He-flash at the tip of the red giant branch (RGB) or while ascending the brightest portion of the RGB.Comment: 7 pages, 2 figures. Accepted for publication in A&A Letter

Research of writing in primary education in Chile: A review of decade (2007-2016)

Indexación: Scopus; Scielo.Por otra parte, se observa que los investigadores han adoptado enfoques teó-ricos provenientes de la lingüística, la didáctica de la lengua y de los modelos cognitivos y socioculturales para indagar e interpretar la enseñanza de la escri-tura en las aulas. En el aspecto teórico, nos parece relevante establecer mayores puentes entre los investigadores nacionales del área para establecer debates in-terdisciplinarios acerca de las actuales teorías del aprendizaje de la escritura en la infancia y la niñez (Bazerman et al., 2017, 2018; Beard et al., 2009; Berninger, 2012; Grigorenko et al., 2012) y de modelos de enseñanza de la escritura en la educación básica (Fidalgo et al., 2017; Graham, MacArthur y Fitzgerald, 2013), que permitan establecer marcos teóricos más integrales que orienten las bases curriculares y la formación inicial y en servicio del profesorado, a la luz de las evidencias científicas en el área.La revisión aporta una síntesis de las investigaciones de la escritura en la educación básica realizadas durante el periodo 2007-2016 en Chile. Mediante el método de revisión integradora se identificaron 27 fuentes académicas que fueron clasificadas y analizadas en dos grandes áreas de estudio: aprendizaje de la escritura y enseñanza de la escritura. En el área del aprendizaje de la escritura de los estudiantes, las investigaciones se han enfocado principalmente en el análisis de conocimientos lingüísticos (ortografía y producción de oraciones) y en la valoración de la calidad de los textos, en su mayoría en textos narrativos, y en menor medida expositivos y de opinión. Por su parte, en el área de la enseñanza de la escritura, la atención se ha puesto principalmente en entender las prácticas de enseñanza de la composición de cuentos o textos de opinión. Menor atención han dedicado al estudio de las prácticas de evaluación de la escritura y de las necesidades de formación inicial y continua del profesorado relacionadas con la didáctica de la escritura. Destaca también la ausencia de encuestas nacionales y de estudios observacionales con docentes de otras regiones distintas a la Región Metropolitana, que permitan disponer de un panorama más completo de las prácticas de enseñanza de la escritura que ocurren en los diversos contextos educacionales, en términos de las estrategias de enseñanza y evaluación, así como de los géneros textuales que utilizan los docentes para enseñar a escribir, además de la frecuencia con la que enseñan la escritura, en comparación con los ejes de lectura y oralidad. A partir de una síntesis de resultados en cada área, la revisión propone recomendaciones para futuros estudios de la escritura en el contexto chileno de educación básica.The review provides a synthesis of the basic education writing research carried out during the 2007-2016 period in Chile. Through the integrative review method, 27 academic sources were identified and classified into two main areas of study: writing learning and writing instruction. In the area of student writing learning, research has focused mainly on the analysis of linguistic knowledge (spelling and sentence production) and the evaluation of the quality of texts, mostly in narrative texts, and to a lesser extent expository and opinion. In the area of teaching writing, attention has been focused mainly on understanding the teaching practices of story writing or opinion texts. Less attention, they have dedicated to the study of the practices of evaluation of the writing and of the needs of initial and continuous formation of the professors related to the didactics of the writing. It also highlights the absence of national surveys and observational studies with teachers from other regions than the Metropolitan Region, which provide a more complete picture of the teaching practices of writing that occur in different educational contexts, in terms of teaching and evaluation strategies, as well as the text genres that teachers use to teach writing, in addition to the frequency with which they teach writing, compared to the teaching of reading and orality. Based on a synthesis of results in each area, the review proposes recommendations for future studies of writing in the Chilean context of basic education.https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0718-48832018000100059&lng=en&nrm=iso&tlng=e

Urban territorial restructuring : a balance of a decade of application of the rehabilitation program of neighborhoods : from neighborhood management towards eco-neighborhood governance

Los progresivos cambios desde un enfoque disciplinar a uno sistémico implica el desafío de profundizar en la articulación de avances provenientes de diversas disciplinas que coexisten en un territorio común. De allí es que el plantear el reordenamiento territorial de las preexistencias y sus problemas se traduce en un desafío disciplinar que implica focalizar la gobernanza de territorios urbanos a escala local de manera de encontrar aquellas variables irreductibles que permitan rehabilitar comunidades en progresivo deterioro, profundizar en estrategias de regeneración del tejido social vulnerado y proponer directrices de trabajo validadas desde la praxis de manera de disminuir la incertidumbre actual en la toma de decisiones a escala local. Solo de esta manera, se puede lograr avances efectivos en la sustentabilidad urbana. La experiencia chilena del Programa de Rehabilitación de Barrios, desarrollada durante la última década por el Ministerio de Vivienda y Urbanismo, desde la condición base de vulnerabilidad permite reconocer aspectos esenciales en la dimensión política del Ordenamiento Territorial.The progressive changes from a disciplinary approach to a systemic one imply the challenge of deepening the articulation of advances coming from diverse disciplines that coexist in a common territory. Proposing territorial restructuring of the pre-existences and their problems means a disciplinary challenge that implies focusing the governance of urban territories at a local level in order to find those irreducible variables that allow the rehabilitation of communities in progressive deterioration, to deepen strategies of regeneration of the damaged social structure, and to propose work guidelines validated from the praxis in order to reduce the current uncertainty in decision making at the local level. Only in this way can effective progress be made in urban sustainability. The Chilean experience of the Neighborhood Rehabilitation Program developed during the last decade by the Housing and Urban Development Department, from the base condition of vulnerability allows to recognize essential aspects in the political dimension of Land-use Planning.Fil: Pino N., Eliana. Santiago de Chile (Chile). Universidad Tecnológica MetropolitanaFil: Yurisch, Telye. Santiago de Chile (Chile). Universidad Tecnológica MetropolitanaFil: Silva, Christopher. Santiago de Chile (Chile). Universidad Tecnológica MetropolitanaFil: Toledo, Cristopher. Santiago de Chile (Chile). Universidad Tecnológica MetropolitanaFil: Ahumada G., Néstor. Santiago de Chile (Chile). Universidad Tecnológica Metropolitan

Operational Observatory of the catalan sea (OOCS)

The Operational Observatory of the Catalan Sea (OOCS) recently created by the Operational Oceanography Group at CEAB-CSIC is presented. The OOCS aims at performing observations of the marine environment in the Catalan Sea and beyond, assessing, modelling and forecasting the hydrodynamic and biogeochemical processes of the region. Some of the biogeochemical variables available in the models and forecast are phytoplankton, zooplankton and nutrients. Although OOCS is expected to be fully operational in 2011, some of its services are already available to the public through a dedicated webpage http://www.ceab.csic.es/~simob/.Peer Reviewe

NGC 2849 and NGC 6134: two more BOCCE open clusters

We present CCD photometry of two southern open clusters. As part of the Bologna Open Cluster Chemical Evolution project we obtained BVI and UBVI imaging for NGC 2849 and NGC 6134, respectively. By means of the synthetic colour-magnitude diagram method and using various evolutionary sets of stellar evolution tracks with various metallicities, we determined at the same time age, distance and reddening. We also determined an approximate metallicity for NGC 2849, for which the information is not available from sounder methods like high-resolution spectroscopy. NGC 2849 turned to be 0.85-1.0 Gyr old with a solar metallicity. The foreground reddening is E(B - V) = 0.28 - 0.32, and the true distance modulus (m - M) 0 = 13.8-13.9. For NGC 6134 we did not obtain fully consistent answers from the V, B - V and V, V - I photometry, an unexpected problem, since both the metallicity and the reddening are known (from high-resolution spectroscopy and the U - B, B - V two colours diagram, respectively). This may either indicate a difficulty of current models (evolutionary tracks and/or models of atmosphere) to accurately reproduce colours, or be related to differences in the metal mixture assumed by the models and those of the clusters. Assuming the spectroscopic abundance and the colour excess [E(B - V) = 0.35] from the U - B, B - V plot, we derived a best age between 0.82 and 0.95 Gyr and a distance modulus 10.5. In agreement with previous studies, the NGC 6134 colour-magnitude diagram shows also a clear main sequence gap at V ˜ 15 and B-V ˜ 0.9-1.0 that is unexplained by canonical stellar evolution models.Fil: Ahumada, Andrea Veronica. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Cordoba. Observatorio Astronomico de Cordoba. Departamento de Astrofisica Estelar; ArgentinaFil: Cignoni, M.. Universitá di Bologna. Dipartimento di Astronomia; Italia;Fil: Bragaglia, A.. INAF-Osservatorio Astronomico di Bologna; Italia;Fil: Donati, P.. Universitá di Bologna. Dipartimento di Astronomia; Italia;Fil: Tosi, M.. INAF-Osservatorio Astronomico di Bologna; Italia;Fil: Marconi, G.. European Southern Observatory (ESO); Chile

Simple Stellar Population Models as probed by the Large Magellanic Cloud Star Cluster ESO 121-SC03

The presence of blue straggler stars (BSs) in star clusters has proven a challenge to conventional simple stellar population (SSP) models. Conventional SSP models are based on the evolution theory of single stars. Meanwhile, the typical locations of BSs in the colour-magnitude diagram of a cluster are brighter and bluer than the main sequence turn-off point. Such loci cannot be predicted by single-star evolution theory. However, stars with such properties contribute significantly to the integrated light of the cluster. In this paper, we reconstruct the integrated properties of the Large Magellanic Cloud cluster ESO 121-SC03, based on a detailed exploration of the individual cluster stars, and with particular emphasis on the cluster's BSs. We find that the integrated light properties of ESO 121-SC03 are dramatically modified by its BS component. The integrated spectral energy distribution (ISED) flux level is significantly enhanced toward shorter wavelengths, and all broad-band colours become bluer. When fitting the fully integrated ISED of this cluster based on conventional SSP models, the best-fitting values of age and metallicity are significantly underestimated compared to the true cluster parameters. The age underestimate is $\sim40$ per cent if we only include the BSs within the cluster's half-light radius and $\sim60$ per cent if all BSs are included. The corresponding underestimates of the cluster's metallicity are $\sim30$ and $\sim60$ per cent, respectively. The populous star clusters in the Magellanic Clouds are ideal objects to explore the potential importance of BSs for the integrated light properties of more distant unresolved star clusters in a statistically robust manner, since they cover a large range in age and metallicity.Comment: 11 pages, 7 figures, 2 tables, accepted for publication in MNRA

The blue straggler population of the open clusters Trumpler 5, Trumpler 20, and NGC 2477

We present a study, based on Gaia DR2, of the population of blue straggler stars (BSS) in the open clusters Trumpler 5, Trumpler 20, and NGC 2477. All candidates were selected according to their position in the color-magnitude diagram, to their proper motion components, and to their parallax. We also looked for yellow stragglers, i.e., possible evolved blue stragglers. We found that Trumpler 5 hosts a large BSS population, which allowed us to analyze their radial distribution as a probe of the cluster's dynamical status. The BSS distribution was compared with that of red giant branch stars (RGB) to evaluate mass segregation. Our results indicate that blue straggler stars are not more centrally concentrated than RGB stars in any of the clusters. The radial distribution of BSS in Trumpler 5 is flat. Additionally, using a multi-epoch radial velocity survey conducted with the high-resolution spectrograph FLAMES/GIRAFFE at VLT, we measured the radial velocities of a sample of stragglers, for the sake of comparison with the mean radial velocity and the velocity dispersion of the clusters. Based on the radial velocity variations for different epochs, we roughly classified these stars as possible close-or long-period binaries.Comment: 20 pages, 5 figures, accepted for publication in A