State-selective Capture In Collisions Between Ions And Ground- And Excited-state Alkali-metal Atoms

Total cross sections for state-selective electron capture in collisions between ions and alkali-metal atoms have been calculated by means of a three-body classical-trajectory Monte Carlo (CTMC) method using model potentials to describe the electron ionic-core interactions. Calculations have been performed for Na+-Na(28d) collisions and for N5+ and Ar8+-Cs(6s) collisions. The collision velocity range corresponds to 0.5vp/ve2, where vp is the projectile velocity in the laboratory frame and ve is the initial orbital velocity of the electron bound to the alkali-metal core. In the case of Na++Na(28d) collisions, calculations of the final n,l,m distributions show the importance of the electron-capture cross sections into states with m\u3e1. For the case of multiply charged ion Cs(6s) collisions, a predominance of electron captures to nearly circular states (large l values) are predicted for cross sections near the maximum of the n distribution. When the e- Cs+ interaction is described by a realistic model potential, the CTMC calculations are found to be in good agreement with recent measurements of the final n values that are predominantly populated after single-electron capture. © 1990 The American Physical Society

Nueva fórmula para la estimación agroclimática de las horas de frío

p.139-144Utilizando valores climáticos corrientes se desarrolló una fórmula para estimar la magnitud del enfriamiento disponible durante el descanso de frutales criófilos al cual se lo considera extendido entre el 1º de mayo y el 31 de agosto. Para ello se utilizó la información climática de horas de frío medias mensuales de la serie 1971-2000 calculadas mediante la formula de Parton y Logan (1981) aplicada a valores diarios. Los valores obtenidos mediante la nueva fórmula propuesta manifiestan excelente correlación con los valores calculados, observándose entre ambas series diferencias muy pequeñas con un error absoluto medio de alrededor de 3 por ciento

Control strategy and performance of a small-size thermally integrated Carnot battery based on a Rankine cycle and combined with district heating

To encourage decarbonization and promote a widespread penetration of renewable energy sources in all energy sectors, the development of efficient energy storage systems is essential. Interesting grid-scale electricity storage technologies are the Carnot batteries, whose working principle is based on storing electricity in the form of thermal energy. The charging phase is performed through a heat pump cycle, and the discharging phase is conducted through a heat engine. Since both thermal and electric energy flows are involved, Carnot batteries can be adopted to provide more flexibility in heat and power energy systems. To this aim, efficient scheduling strategies are necessary to manage different energy flows. In this context, this work presents a detailed rule-based control strategy to schedule the synergetic work of a 10-kWe reversible heat pump/organic Rankine cycle Carnot battery integrated to a district heating substation and a photovoltaic power plant, to satisfy a local user's thermal and electric demand. The coupling of a Carnot battery with a district heating substation allows for shaving the thermal demand peaks through the thermal energy stored in the Carnot battery storage, allowing for a downsizing of the district heating substation, with a considerable reduction of the investment costs. Due to the multiplicity of the involved energy flows and the numerous modes of operation, a scheduling logic for the Carnot battery has been developed, to minimize the system operating costs, depending on the boundary conditions. To investigate the influence of the main system design parameters, a detailed and accurate model of the Carnot battery is adopted. Two variants of the reference system, with different heat pump cold source arrangements, are investigated. In the first case, the heat pump absorbs thermal energy from free waste heat. In the second case, the heat pump cold source is the return branch of the district heating substation. The simulation results show that, in the first case, the Carnot battery allows the downsizing of the district heating substation by 47 %, resulting in an annual gain of more than 5000 €. About 70 % of the economic benefit is due to the possibility of reducing the power size of the district heating substation, which can be from 300 to more than 500 kW. The payback period is estimated to be lower than 9 years, while in the second case, the Carnot battery is not able to provide a gain. Eventually, the influence of some parameters, such as the photovoltaic power plant surface, the storage volume, the electricity price profile and the reversible heat pump/organic Rankine cycle specific investment cost, on the techno-economic performance of the system, is investigated through a wide sensitivity analysis. According to the results, the photovoltaic panels surface does not significantly affect the economic gain, while the storage capacity strongly affects the system scheduling and the operating costs. Indeed, it is possible to identify that 13 m3 is the size of the storage volume that minimizes the payback period to 8.22 years, for the considered application. An increase in the electricity price without an increase in the thermal energy price leads to a decrease in economic gain because the benefit brought by the downsizing of district heating is less significant on the economic balance. The specific investment cost of the reversible heat pump/organic Rankine cycle does not influence the operating cost; thus, it does not change the Carnot battery management, nor the economic gain. The specific investment cost affects the payback period, which increases from 8.6 years for a specific cost of 2000 €/kWe to 15.7 years for a specific cost of 5000 €/kWe

Which tools for scientific current awareness in Cemagref?

pp. 19-3

Amplitud térmica extrema anual en la Argentina en el período 1965 - 2000

p.173-178Se analiza la variación que manifestó la amplitud térmica extrema anual en la Argentina en los últimos 35 años del Siglo XX, a través de la tendencia de las temperaturas máximas y mínimas absolutas anuales. Con excepción de la Región Mesopotámica, en las cuales la variación es nula o poco positiva, el resto del territorio manifiesta una variación en disminución, que alcanza su mayor expresión (-5,6°C) en la parte centro - occidental de la Pradera Pampeana. Es posible, que esta variación esté asociada al aumento de las cantidades anuales de precipitación en el mismo período

A better characterization of the chemical composition of exoplanets atmospheres with ARIEL

Since the discovery of the first extrasolar planet more than twenty years ago, nearly four thousand planets orbiting stars other than the Sun (http://exoplanet.eu/) have been discovered. Current observational instruments (on board the Hubble Space Telescope, Spitzer, and on ground-based facilities) have allowed the scientific community to obtain important information on the physical and chemical properties of these planets. However, for a more in-depth characterisation of these worlds, more powerful telescopes are needed. Thanks to the high sensitivity of their instruments, the next generation of space observatories (e.g. JWST, ARIEL) will provide observations of unprecedented quality, allowing us to extract far more information than what was previously possible. Such high quality observations will provide constraints on theoretical models of exoplanet atmospheres and lead to a greater understanding of their physics and chemistry. Important modelling efforts have been carried out during the past few years, showing that numerous parameters and processes (such as the elemental abundances, temperature, mixing, etc.) are likely to affect the atmospheric composition of exoplanets and subsequently the observable spectra. In this manuscript, we review the different parameters that can influence the molecular composition of exoplanet atmospheres. We show that the high-precision of ARIEL observations will improve our view and characterisation of exoplanet atmospheres. We also consider future developments that are necessary to improve atmospheric models, driven by the need to interpret the available observations

Depth profile investigations of surface modifications of limestone artifacts by laser-induced breakdown spectroscopy.

Made available in DSpace on 2017-11-01T23:23:05Z (GMT). No. of bitstreams: 1 PROCI17Depthprofileinvestigations....pdf: 1977315 bytes, checksum: f46ba065d28554ead651738267cea5a4 (MD5) Previous issue date: 2017-10-30bitstream/item/165807/1/PROCI-17-Depth-profile-investigations....pd

BLAST Observations of the South Ecliptic Pole field: Number Counts and Source Catalogs

We present results from a survey carried out by the Balloon-borne Large Aperture Submillimeter Telescope (BLAST) on a 9 deg^2 field near the South Ecliptic Pole at 250, 350 and 500 {\mu}m. The median 1{\sigma} depths of the maps are 36.0, 26.4 and 18.4 mJy, respectively. We apply a statistical method to estimate submillimeter galaxy number counts and find that they are in agreement with other measurements made with the same instrument and with the more recent results from Herschel/SPIRE. Thanks to the large field observed, the new measurements give additional constraints on the bright end of the counts. We identify 132, 89 and 61 sources with S/N>4 at 250, 350, 500 {\mu}m, respectively and provide a multi-wavelength combined catalog of 232 sources with a significance >4{\sigma} in at least one BLAST band. The new BLAST maps and catalogs are available publicly at http://blastexperiment.info.Comment: 25 pages, 6 figures, 4 tables, Accepted by ApJS. Maps and catalogs available at http://blastexperiment.info