Catálogo de publicaciones - revistas

<jats:p> In this paper, the parameters influencing the installed power demand as well as the installed and normalised power density for road lighting are introduced. The levels of these parameters typical for different road lighting situations are assumed and the resulting normalised power densities for road lighting are derived. A classification system for the energy efficiency of road lighting based on the installed and normalised power densities is proposed. The classification system can be used to compare the energy efficiency of designed and used road lighting as well as forming a basis for an energy efficiency evaluation system for road lighting. </jats:p>

<jats:p> The application of memory and preferred colours to colour rendition evaluation of white light sources is reviewed. Four metrics are discussed: Sanders’ preferred colour index, Judd’s flattery index, Thornton’s colour preference index and Smet’s memory colour rendition index. Following a review of the metrics themselves, the paper continues with a discussion of their predictive performance in terms of agreement with psychophysical data on visual appreciation and naturalness perception. Their performance was also compared to that of several other colour rendition metrics and the impact on the predictive performance of a metric’s emphasis on chroma enhancement has been evaluated. </jats:p>

<jats:p> This paper presents a detailed analysis of the capabilities of imaging luminance measuring devices for determining discomfort glare. Common opinions on light-emitting diode (LED)-based street lighting luminaires say these products cause high glare. This paper contains the results of calculations and thoughts on the potential measurement errors arising from the incompatibility of the measuring device parameters (number of pixels, sensor dimensions and focal length) to the resolution of the human eye. There are also some cases presented where this incompatibility is of the highest importance, i.e., for the luminance distribution measurements connected with identifying a discomfort glare problem caused, in particular, by multi-source LED luminaires. </jats:p>

<jats:p> Luminous intensity distributions enable an evaluation of the spatial radiation characteristic of a light source. This radiation characteristic is determined by the structural properties of the light source, its operating parameters and the properties of the measuring system. This paper describes some possible methods and rules for comparing luminous intensity distributions. The focus is on the development of calculation rules for quantifying the differences between two luminous intensity distributions. The difference measures developed allow the user to establish an objective comparison between luminous intensity distributions, this comparison being completely independent of the measuring system, the properties of the luminous intensity distributions and the users themselves. Further, the dependence of the properties of luminous intensity distributions resulting from measurement practice, such as adjustment uncertainties, regions that cannot be covered or measured, deviations of the total luminous flux, data noise and resolution differences, are discussed, and appropriate pre-processing and correction steps proposed. In addition, various visualisations of the differences between two luminous intensity distributions are demonstrated and the functionality of the difference measures developed is documented. </jats:p>

<jats:p> Along with the high energy-efficiency potential, light-emitting diode (LED) lighting provides the possibility for spectrum control. Our study presents the original data on the influence of LED light spectrum quality on the growth and macro- and micro-nutrient uptake of lettuce ( Lactuca sativa L. cv. Frillice) plants cultivated in indoor conditions and without daylight. Four LED light spectral combinations were investigated using conventional high-pressure sodium (HPS) lighting as a control. In general, the LED light spectra were more favourable than the HPS light spectrum for promoting the growth and nutrient uptake of plants. In particular, the light spectrum provided by the combination of the far-red, deep-red and blue LEDs had the highest growth and nutrient uptake indices. This spectral combination particularly enhanced the uptake of potassium, calcium and magnesium in comparison to control plants grown under conventional HPS lamps. The uptake of iron and zinc were significantly influenced by the spectral changes of the red and blue light. </jats:p>

<jats:p> Year-round greenhouse production in northern latitudes depends on the use of artificial lighting. Light emitting diodes provide a promising means to save energy during cultivation as well as to modify the light spectrum to regulate the growth and quality of the crop. We compared the effects of light emitting diode lighting with different spectral compositions on the growth, development and nutritional quality of lettuce ( Lactuca sativa L. ‘Frillice’). We show that warm-white and warm-white supplemented with blue spectra provide equal growth and product quality compared to conventional high-pressure sodium lighting in the absence and presence of daylight. Our data indicate that for biomass accumulation, the far-red component in the light spectrum is more critical than green light or the red/blue ratio. Furthermore, we demonstrate that a red + blue spectrum increases the concentration of several vitamins in lettuce. However, biomass accumulation using this spectrum was insufficient when daylight was excluded. </jats:p>

<jats:p> In order to compare drivers’ subjective impressions when exposed to high-pressure sodium versus LED street lighting, an experiment was conducted on a Belgrade street. All general requirements for an adequate comparison of subjective impressions, equal luminances being the most important, were fulfilled. A survey was conducted using a questionnaire, which the respondents filled out immediately after driving through both zones of the illuminated street. The respondents, who were young drivers (students), aged 20–25 years, were asked to select the more appropriate of the two installations regarding seven lighting parameters as well as giving their overall impression. The two regimes for which the survey was done gave opposite results. In the normal regime, where both installations had the same photopic luminance, the LED installation was evaluated as a better solution by a majority of the respondents for most of the analysed parameters. In the mesopic regime, where both installations had the same mesopic luminance, most of the respondents judged that the high-pressure sodium installation was the better choice. </jats:p>