Self-accretion of matter,red subluminous stars and early evolution of low-mass stars     

V. Castellani  N. Panagia 《Astrophysics and Space Science》1972,15(3):462-466

Low-mass stars during their pre-main sequence contraction phase are expected to be surrounded by a certain amount of the primordial gas. At low luminosities, accretion of this gas can make the stars to follow a peculiar evolutionary course which can account for certain types of red subluminous stars. The efficiency of the accretion mechanism can also account for some peculiarities in the spectra of the stars of low mass.

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Sommario Stelle di bassa massa in fase di contrazione pre-sequenza sono con ogni probabilità circondate da abbondante gas. In queste condizioni al diminuire della luminosità può divenire efficiente il meccanismo di accrescimento, cosi da condurre la stella su una linea evolutiva del tutto peculiare. Una simile evoluzione può rendere conto di oggetti sottoluminosi e a bassa temperatura, come pure di alcune peculiarità negli spettri di stelle di bassa massa.

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The accretion of interstellar matter by white dwarfs     

Vittorio Castellani  Nino Panagia 《Astrophysics and Space Science》1971,10(1):122-135

The problem of the energy released by interstellar matter in its accretion by low-luminosity stars is examined. It is found that nearly all the gravitational energy is available as the energy source for the accreting star. When this source of energy becomes predominant, a luminosity-temperature relation can be derived.Evolutionary consequences for the white dwarfs are discussed.The behaviour of selected classes of white dwarfs is recognized in the theoretical H.R. diagram.The evidence for a separation between field white dwarfs and Hyades cluster's white dwarfs is shortly discussed. For the Hyades white dwarfs a well defined sequence in good agreement with a constant accretion locus is found.A critical discussion is finally given on the efficiency of the accretion mechanism in the Hyades dwarfs.

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Sommario Viene discusso il problema dell'energia ceduta dalla materia interstellare nei processi di cattura gravitazionale da parte di oggetti stellari di bassa luminosità. Si mostra come le maggior parte di questa energia sia effettivamente ceduta alla struttura stellare.Nei casi in cui l'energia di accrescimento predomini sulle altre sorgenti di energia è possibile ricavare una relazione luminosità-temperatura. Sono discusse possibili conseguenze sull'evoluzione delle nane bianche.E'esaminato il comportamento di alcune classi di nane bianche nel diagramma H.R. teorico, e viene brevemente discussa l'evidenza per una reale separazione delle nane bianche di campo da quelle nell'ammasso delle Iadi. Per queste ultime in particolare si trova una sequenza molto ben definita, in ottimo accordo con un luogo di costante accrescimento.Un esame critico è infine compiuto riguardo la possibile efficienza dell'accrescimento nelle nane delle Iadi.

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A parametric approach to the slope of the globular clusters giant branches     

Vittorio Castellani  Daniele Palma 《Astrophysics and Space Science》1977,47(1):217-223

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Measurement of a Peak in the Cosmic Microwave Background Power Spectrum from the North American Test Flight of Boomerang     

Mauskopf PD  Ade PA  de Bernardis P  Bock JJ  Borrill J  Boscaleri A  Crill BP  DeGasperis G  De Troia G  Farese P  Ferreira PG  Ganga K  Giacometti M  Hanany S  Hristov VV  Iacoangeli A  Jaffe AH  Lange AE  Lee AT  Masi S  Melchiorri A  Melchiorri F  Miglio L  Montroy T  Netterfield CB  Pascale E  Piacentini F  Richards PL  Romeo G  Ruhl JE  Scannapieco E  Scaramuzzi F  Stompor R  Vittorio N 《The Astrophysical journal》2000,536(2):L59-L62

We describe a measurement of the angular power spectrum of anisotropies in the cosmic microwave background (CMB) at scales of 0&fdg;3 to 5 degrees from the North American test flight of the Boomerang experiment. Boomerang is a balloon-borne telescope with a bolometric receiver designed to map CMB anisotropies on a long-duration balloon flight. During a 6 hr test flight of a prototype system in 1997, we mapped more than 200 deg(2) at high Galactic latitudes in two bands centered at 90 and 150 GHz with a resolution of 26&arcmin; and 16&farcm;5 FWHM, respectively. Analysis of the maps gives a power spectrum with a peak at angular scales of 1 degrees with an amplitude 70 μK(CMB).  相似文献   

Environmental impacts of household appliances in Europe and scenarios for their impact reduction     

Roland Hischier  Francesca Reale  Valentina Castellani  Serenella Sala 《Chemie der Erde / Geochemistry》2011

Assessing the environmental impact due to consumption of goods and services is a pivotal step towards achieving the sustainable development goal related to responsible production and consumption (i.e. SDG 12). Household appliances plays a crucial role and should be assessed in a systemic manner, namely considering all life cycle stages, technological efficiency, and affluence aspects. The present study assess the impact of such household appliances used in Europe, and tests scenarios of potential impact reduction at various scales. Life cycle assessment is applied to 14 different household appliances (ranging from dishwashers to television devices) selected to build a set of representative products, based on their economic value and diffusion in households in Europe. Related impacts are calculated with the Environmental Footprint method for calculating a Consumer Footprint “appliances” for the baseline year 2010. A number of scenarios encompassing eco-solutions on a technical level, changes in consumption pattern, behavioral changes, as well as the combination of all these aspects are run to estimate the Consumer Footprint related to household appliances for the year 2030, compared against this baseline scenario. The baseline Consumer Footprint is confirming the importance of the use phase in leading the impacts in almost all impact categories. Testing different scenarios concludes that there is a reduction of the impact for most of the categories (with up to 67% for the ozone depletion potential, and still around 35% for the global warming potential), while two of the here examined impact categories (i.e. land-use and mineral resource depletion) show an overall potential that is even negative – i.e. the results of all scenarios are higher than the ones of the 2010 baseline scenario. The increase in purchase and use of such appliances may offset energy efficiency benefits in some of the examined categories. Hence, the assessment of sustainability of appliances consumption should always include several scales, from the efficiency of the products (micro scale), to the improvement of the energy mix (meso scale), up to accounting for socio-economic drivers and patterns of consumption affecting the overall appliances stock (macro scale).  相似文献   

Space distribution of evolving stars in M13     

Assia Blaghikh  Vittorio Castellani 《Astrophysics and Space Science》1971,12(1):208-218

Information about space distribution is collected for selected classes of evolving stars in the globular cluster M13. After a rigorous elimination of field stars, three samples are examined, corresponding to the red giant stage (G), the blue (B) and the yellow (YG) parts of the horizontal branch. It is shown that results are easy to understand in terms of:

1. A substantial mass loss in the H-shell burning stage;
2. Evolution along the horizontal branch from the blue side to the red one;
3. A mixing in the observed giant branch of two populations with sensible differences in masses.

Theoretical interpretations are briefly discussed with reference to the reliability and usefulness of this type of investigation.  相似文献   

M10 and M12: A couple of interacting twin globular clusters?     

R. Buonanno  V. Castellani  F. Smriglio 《Astrophysics and Space Science》1976,41(1):L3-L7

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Environmental impacts of household appliances in Europe and scenarios for their impact reduction     

Roland Hischier  Francesca Reale  Valentina Castellani  Serenella Sala 《Chemie der Erde / Geochemistry》2013

Assessing the environmental impact due to consumption of goods and services is a pivotal step towards achieving the sustainable development goal related to responsible production and consumption (i.e. SDG 12). Household appliances plays a crucial role and should be assessed in a systemic manner, namely considering all life cycle stages, technological efficiency, and affluence aspects. The present study assess the impact of such household appliances used in Europe, and tests scenarios of potential impact reduction at various scales. Life cycle assessment is applied to 14 different household appliances (ranging from dishwashers to television devices) selected to build a set of representative products, based on their economic value and diffusion in households in Europe. Related impacts are calculated with the Environmental Footprint method for calculating a Consumer Footprint “appliances” for the baseline year 2010. A number of scenarios encompassing eco-solutions on a technical level, changes in consumption pattern, behavioral changes, as well as the combination of all these aspects are run to estimate the Consumer Footprint related to household appliances for the year 2030, compared against this baseline scenario. The baseline Consumer Footprint is confirming the importance of the use phase in leading the impacts in almost all impact categories. Testing different scenarios concludes that there is a reduction of the impact for most of the categories (with up to 67% for the ozone depletion potential, and still around 35% for the global warming potential), while two of the here examined impact categories (i.e. land-use and mineral resource depletion) show an overall potential that is even negative – i.e. the results of all scenarios are higher than the ones of the 2010 baseline scenario. The increase in purchase and use of such appliances may offset energy efficiency benefits in some of the examined categories. Hence, the assessment of sustainability of appliances consumption should always include several scales, from the efficiency of the products (micro scale), to the improvement of the energy mix (meso scale), up to accounting for socio-economic drivers and patterns of consumption affecting the overall appliances stock (macro scale).  相似文献   

Neural network approach to prediction of temperatures around groundwater heat pump systems     

Stefano Lo Russo  Glenda Taddia  Loretta Gnavi  Vittorio Verda 《Hydrogeology Journal》2014,22(1):205-216

A fundamental aspect in groundwater heat pump (GWHP) plant design is the correct evaluation of the thermally affected zone that develops around the injection well. This is particularly important to avoid interference with previously existing groundwater uses (wells) and underground structures. Temperature anomalies are detected through numerical methods. Computational fluid dynamic (CFD) models are widely used in this field because they offer the opportunity to calculate the time evolution of the thermal plume produced by a heat pump. The use of neural networks is proposed to determine the time evolution of the groundwater temperature downstream of an installation as a function of the possible utilization profiles of the heat pump. The main advantage of neural network modeling is the possibility of evaluating a large number of scenarios in a very short time, which is very useful for the preliminary analysis of future multiple installations. The neural network is trained using the results from a CFD model (FEFLOW) applied to the installation at Politecnico di Torino (Italy) under several operating conditions. The final results appeared to be reliable and the temperature anomalies around the injection well appeared to be well predicted.  相似文献   

Latent Exurban Development: City Expansion Along the Rural-To-Urban Gradient in Growing and Declining Regions of Southern Europe     

Luca Salvati  Vittorio Gargiulo Morelli  Kostas Rontos  Alberto Sabbi 《Urban geography》2013,34(3):376-394

This paper quantifies the extent of exurban development in Mediterranean Europe. The assessment was carried out by studying changes in the urban-to-rural population density gradient between the years 1950 and 2010. Three of the six urban regions in this study have experienced population growth and moderate urban concentration, while two regions appear to be shifting toward population decline and urban de-concentration after having experienced compact expansion. A phase of recent re-urbanization has been observed in one region. Altogether, these findings indicate a common path of urban expansion among representative Mediterranean regions between 1950 and 1980 while, in the following period, the cities experienced distinct development phases. From this study, we conclude that exurban development is mainly the product of a shift from compact and dense to semi-compact and intermediate-density settlements. [Key words: semi-dense urban growth, density-distance curve, Mediterranean Europe].  相似文献