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Author |
Bará, S. |
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Title |
Naked-eye astronomy: optics of the starry night skies |
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Journal Article |
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Year |
2014 |
Publication |
Proc. SPIE 9289, 12th Education and Training in Optics and Photonics Conference, 2014 |
Abbreviated Journal |
Proc. SPIE 9289 |
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9289 |
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Keywords |
Society; light pollution |
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Abstract |
The world at night offers a wealth of stimuli and opportunities as a resource for Optics education, at all age levels and from any (formal, non formal or informal) perspective. The starry sky and the urban nightscape provide a unique combination of pointlike sources with extremely different emission spectra and brightness levels on a generally darker, locally homogeneous background. This fact, combined with the particular characteristics of the human visual system under mesopic and scotopic conditions, provides a perfect setting for experiencing first-hand different optical phenomena of increasing levels of complexity: from the eye's point spread function to the luminance contrast threshold for source detection, from basic diffraction patterns to the intricate irradiance fluctuations due to atmospheric turbulence. Looking at the nightscape is also a perfect occasion to raise awareness on the increasing levels of light pollution associated to the misuse of public and private artificial light at night, to promote a sustainable use of lighting, and to take part in worldwide citizen science campaigns. Last but not least, night sky observing activities can be planned and developed following a very flexible schedule, allowing individual students to carry them out from home and sharing the results in the classroom as well as organizing social events and night star parties with the active engagement of families and groups of the local community. This contribution describes these possibilities and introduces some of the free resources available to put them in practice. |
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Univ. de Santiago de Compostela, Spain; salva.bara@usc.es |
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SPIE |
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English |
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English |
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IDA @ john @ |
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1134 |
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Author |
Bará, S. |
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Title |
Light pollution and solid-state lighting: reducing the carbon dioxide footprint is not enough |
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Journal Article |
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Year |
2014 |
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Proc. SPIE 8785, 8th Iberoamerican Optics Meeting and 11th Latin American Meeting on Optics, Lasers, and Applications, 87852G, 2013 |
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Proc. SPIE 8785 |
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8785 |
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Keywords |
*Lighting; LED; light emitting diode; outdoor lighting; artificial light at night; lighting policy; solid-state lighting; blue light |
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Abstract |
Public and private lighting account for a relevant share of the overall electric power consumption worldwide. The pressing need of reducing the carbon dioxide emissions as well as of lowering the lumen•hour price tag has fostered the search for alternative lighting technologies to substitute for the incandescent and gas-discharge based lamps. The most successful approach to date, solid-state lighting, is already finding its way into the public lighting market, very often helped by substantial public investments and support. LED-based sources have distinct advantages: under controlled conditions their efficacy equals or surpasses that of conventional solutions, their small source size allows for an efficient collimation of the lightbeam (delivering the photons where they are actually needed and reducing lightspill on the surrounding areas), and they can be switched and/or dimmed on demand at very high rates, thus allowing for a tailored schedule of lighting. However, energy savings and carbon dioxide reduction are not the only crucial issues faced by present day lighting. A growing body of research has shown the significance of the spectral composition of light when it comes to assess the detrimental effects of artificial light-at-night (ALAN). The potential ALAN blueshift associated to the deployment of LED-based lighting systems has raised sensible concerns about its scientific, cultural, ecological and public health consequences, which can be further amplified if an increased light consumption is produced due to the rebound effect. This contribution addresses some of the challenges that these issues pose to the Optics and Photonics community. |
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Univ. de Santiago de Compostela, Spain; salva.bara@usc.es |
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SPIE |
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English |
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English |
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IDA @ john @ |
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1135 |
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Author |
Estrada-García, R.; García-Gil, M.; Acosta, L.; Bará, S.; Sanchez de Miguel, A.; Zamorano, J. |
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Title |
Statistical modelling and satellite monitoring of upward light from public lighting |
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Journal Article |
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Year |
2015 |
Publication |
Lighting Research and Technology |
Abbreviated Journal |
Lighting Res. & Tech. |
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1477153515583181 |
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1-30 |
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Keywords |
Remote sensing; radiative transfer; modeling; skyglow; light pollution; urban |
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Abstract |
In this work, we propose an approach to estimating the amount of light wasted by being sent towards the upper hemisphere from urban areas. This is a source of light pollution. The approach is based on a predictive model that provides the fraction of light directed skywards in terms of a small set of identified explanatory variables that characterise the urban landscape and its light sources. The model, built via the statistical analysis of a wide sample of basic urban scenarios to compute accurately the amount of light wasted at each of them, establishes an optimal linear regression function that relates the fraction of wasted flux to relevant variables like the kind of luminaires, the street fill factor, the street width, the building and luminaire heights and the walls and pavement reflectances. We applied this model to evaluate the changes in emissions produced at two urban nuclei in the Deltebre municipality of Catalonia. The results agree reasonably well with those deduced from the radiance measurements made with the VIIRS instrument onboard the Suomi-NPP Earth orbiting satellite. |
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Escola Tècnica Superior d’Enginyeria Industrial de Barcelona (ETSEIB), Universitat Politècnica de Catalunya, Spain; manuel.garcia.gil(at)upc.edu |
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Sage |
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English |
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English |
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Call Number |
IDA @ john @ |
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1155 |
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Author |
Bará, S.; Tilve, V.; Nievas, M.; Sanchez de Miguel, A.; Zamorano, J. |
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Title |
Zernike power spectra of clear and cloudy light-polluted urban night skies |
Type |
Journal Article |
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Year |
2015 |
Publication |
Applied Optics |
Abbreviated Journal |
Appl. Opt. |
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Volume |
54 |
Issue |
13 |
Pages |
4120-4129 |
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Keywords |
Skyglow; artificial ligh at night; light pollution; Zernike; power spectrum; atmospheric optics; imaging systems; image analysis |
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Abstract |
The Zernike power spectra of the all-sky night brightness distributions of clear and cloudy nights are computed using a modal projection approach. The results obtained in the B, V and R Johnson-Cousins' photometric bands during a one-year campaign of observations at a light-polluted urban site show that these spectra can be described by simple power laws with exponents close to -3 for clear nights and -2 for cloudy ones. The second-moment matrices of the Zernike coefficients show relevant correlations between modes. The multiplicative role of the cloud cover, that contributes to a significant increase of the brightness of the urban night sky in comparison with the values obtained in clear nights, is described in the Zernike space. |
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Area de Optica, Dept. Fisica Aplicada. Facultade de Fisica / Facultade de Optica e OptometrÃa Universidade de Santiago de Compostela Campus Sur, E-15782 Santiago de Compostela, Galicia, Spain; salva.bara@usc.es |
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Optical Society of America |
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English |
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English |
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Call Number |
IDA @ john @ |
Serial |
1156 |
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Author |
Reddy, L.; Reddy, V.; Hemanth, S.; Prasad, P. |
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Title |
Modelling and Optimization of Solar Light Trap For “Reducing and Controlling” The Pest Population |
Type |
Journal Article |
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Year |
2015 |
Publication |
International Journal of Engineering Technology, Management and Applied Sciences |
Abbreviated Journal |
Intl. J. of Engr. Tech., Man. & Appl. Sci. |
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3 |
Issue |
4 |
Pages |
224-234 |
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Keywords |
Animals; insects; India; Madanapalli; Chittor; Andhra Pradesh; moonlight; polarization |
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Abstract |
Reducing and controlling the pest population using light traps is an age old practice in our crop sector. Though there are several models and designs are available but we would plan to develop something that could be solar powered trap with collecting net and not dependent on any other source like wind power, mechanical power, fuel & electricity. This device operates automatically, turning on the light during light fails i.e., 6 P.M and turns off before sunrises i.e., 6A.M. Most of the damage causing insects are active only during that time. Installing one light trap in an acre attracts at least more than 1000 adult pests for a day. The insects attract solar light trap model had been tested in our field crops like vegetables, paddy, and sugarcane, fruit crops like mango, pomegranate, guava, coconut and tea, coffee and jasmine crops across India. In this study we examine the relationship between the Lunar Phases and the efficiency of light traps in catching pests in the month of March and April at Madanapalli, Chittor, Andhra Pradesh. The lunar phase depending on the polarized moonlight and the relative catch follow the collecting distance. The collecting distance ranged and averaged in the phase angle divisions. The study demonstrated for the first time the effect of increasing polarized moonlight in the first and last quarter on the flying activity of pests. Catching quantity depend on the connection with the collecting distance when is the greatest of collection distance. |
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Department of Mechanical Engineering, SVTM (J.N.T.U.A) Angallu, Madanapalli ,Chittor (Dist), A.P., India |
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IJETMAS |
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English |
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English |
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IDA @ john @ |
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1161 |
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