Person:
Torres Escribano, José Luis

person.page.identifierURI

https://academica-e.unavarra.es/handle/2454/50087

Last Name

Torres Escribano

First Name

José Luis

person.page.departamento

Ingeniería

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ISC. Institute of Smart Cities

ORCID

0000-0001-9275-8158

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241

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Now showing 1 - 10 of 18

Open Access
Evaluación comparativa de 19 modelos de estimación de irradiancia difusa sobre planos inclinados dependiendo del tipo de cielo estándar ISO/CIE
(LNEG, 2020) García Ruiz, Ignacio; Torres Escribano, José Luis; Blas Corral, María Ángeles de; Sáenz Gamasa, Carlos; Hernández Salueña, Begoña; Illanes, R.; Ingeniería; Ingeniaritza; Ciencias; Zientziak
En este trabajo se han evaluado 19 modelos de estimación de irradiancia difusa sobre el plano inclinado, que incluyen tanto modelos isotrópicos o pseudoisotrópicos como modelos anisotrópicos. Dicha evaluación se ha llevado a cabo a partir una serie de 5396 observaciones de irradiancia global, difusa y directa realizadas entre julio y diciembre de 2018 en la estación radiométrica de la Universidad Pública de Navarra (UPNA). El estado del cielo correspondiente a cada observación se ha caracterizado de acuerdo con el CIE Standard General Sky propuesto en la norma ISO 15469:2004(E)/CIE S 011/E:2003. Para esta clasificación se han utilizado las medidas de distribución angular de luminancia y radiancia proporcionadas por un escáner de cielo ubicado en la propia estación de la UPNA. De tal manera que, para cada combinación de orientación e inclinación del plano, se ha evaluado la bondad de los distintos modelos de acuerdo con los 15 tipos de cielo estándar propuestos por la norma ISO/CIE. Los resultados revelan que el modelo de Perez et al. 2 presenta los mejores resultados globales, así como en 5 de los 15 tipos de cielo ISO/CIE.
Open Access
A GIS-based methodology for assigning experimental measurements of angular distribution of sky radiance and luminance to selected sky sectors
(Elsevier, 2019) García Ruiz, Ignacio; García Gorostiaga, M. Almudena; Torres Escribano, José Luis; Ingeniería; Ingeniaritza; Institute of Smart Cities - ISC
Mathematical models for the estimation of the angular distribution of diffuse radiance/luminance in the sky describe the anisotropic character of diffuse solar radiation and daylight in the sky vault. In most of these models the radiance/luminance of a sky point is determined by the product of the indicatrix function and the gradation function. When developing and/or calibrating these models, it is typical to consider separately the dispersion effects in the direction of the sun's rays and the gradation from the zenith towards the horizon. To do this, the sky is divided into a number of concentric spherical zones around the sun and a number of concentric spherical zones around the zenith. The intersection between both sets of zones delimits a series of sky elements. Unfortunately, these sky elements do not correspond to the 145 patches of sky vault recommended by the International Commission on Illumination (CIE), which are routinely scanned by the existing commercial sky scanners. The identification of the sky elements, geometrically different from those observed by commercial sky scanners, and the assignation of the radiance/luminance values registered by such sky scanners are not analytically trivial tasks. A GISbased methodology is presented in this work to undertake these goals.
Open Access
Generation of the site-adapted clearest-sky year of direct normal irradiance for solar concentrating technologies
(Elsevier, 2018) García Ruiz, Ignacio; Royo Romeo, Alberto; Torres Escribano, José Luis; Proyectos e Ingeniería Rural; Landa Ingeniaritza eta Proiektuak; Gobierno de Navarra / Nafarroako Gobernua
Concentrating photovoltaic and thermoelectric solar facilities base their operation on collecting the direct component of solar radiation. Given that the direct beam that reaches the Earth's surface varies greatly in time and space, it is common to assist the bankability of projects with a solar resource assessment. Sun-tracking collector plants are typically examined via a time series analysis of measured weather data and test reference years. Such analysis, which considers the eventual presence of clouds, may be complemented with the use of the synthetic clear-sky year assuring the maximum theoretical availability of direct normal irradiance at a site. This work introduces for the first time the concept of siteadapted clearest-sky year (CSY) and provides a methodology for its generation. Three methods to build the CSY and one algorithm to detect clear-sky moments are proposed.
Open Access
Luminance calibration of a full sky HDR imaging system using sky scanner measurements
(Solar Energy Society, 2022) García Ruiz, Ignacio; Sáenz Gamasa, Carlos; Hernández Salueña, Begoña; García Santos, Rafael; Torres Escribano, José Luis; Zientziak; Ingeniaritza; Institute of Smart Cities - ISC; Institute for Advanced Materials and Mathematics - INAMAT2; Ciencias; Ingeniería
A full sky High Dynamic Range imaging system, based on a Single-Lens Reflex camera with a fisheye lens, has been constructed and calibrated with a sky scanner luminance meter. The method considers the geometrical, spectral, timing and orientation issues between instruments. The calibration data sets, having nearly simultaneous measurements under stable sky conditions, were obtained from approximately one month of data using selection variables based in the experimental design. For luminance estimation we use the standard 𝐶𝐼𝐸𝑌 RGB combination and a Spectrally Matched Luminance (𝑆𝑀𝐿) predictor, matching the spectral response of the instruments. With 738 calibration points having luminances up to 23.6 kcd∕m2, covering 98.5% of the sky luminance range, 𝐶𝐼𝐸𝑌 is linearly correlated with sky scanner measurements with a coefficient of determination 𝑅2 = 0.9927 and a Root Mean Squared Error (𝑅𝑀𝑆𝐸) of 7.7%. 𝑆𝑀𝐿 gives better results, with 𝑅2 = 0.9973 and 𝑅𝑀𝑆𝐸 = 5.3%. With 253 calibration points with luminances up to 12.9 kcd∕m2, comprising 94.1% of the sky luminance range, both predictors clearly improve, with 𝑅2 = 0.9964 and 𝑅𝑀𝑆𝐸 = 4.1% in case of 𝐶𝐼𝐸𝑌 and 𝑅2 = 0.9982 and 𝑅𝑀𝑆𝐸 = 2.9% in case of 𝑆𝑀𝐿.
Open Access
Evaluación multitemporal de métodos de corrección topográfica mediante el uso de imágenes sintéticas multiespectrales
(Asociación Española de Teledetección, 2014) Sola Torralba, Ion; Álvarez Mozos, Jesús; González de Audícana Amenábar, María; Torres Escribano, José Luis; Proyectos e Ingeniería Rural; Landa Ingeniaritza eta Proiektuak
En este trabajo se presentan los resultados de la evaluación multitemporal de varios métodos de corrección topográfica (TOC), cuya bondad se determina de forma cuantitativa mediante el uso de imágenes sintéticas multiespectrales simuladas para diferentes fechas de adquisición a lo largo del año. Para cada fecha se generan dos imágenes sintéticas, una considerando el relieve real (imagen SR), y otra el relieve horizontal (imagen SH). Las imágenes SR se corrigen utilizando distintos TOC y estas imágenes corregidas se comparan con la corrección ideal (imagen SH) mediante el índice de similitud estructural (SSIM). Los valores de SSIM nos permiten evaluar la eficacia de cada corrección para distintas fechas, es decir, para distintos ángulos de elevación solar.
Open Access
Synthetic images for evaluating topographic correction algorithm
(IEEE, 2013) Sola Torralba, Ion; González de Audícana Amenábar, María; Álvarez Mozos, Jesús; Torres Escribano, José Luis; Proyectos e Ingeniería Rural; Landa Ingeniaritza eta Proiektuak; Gobierno de Navarra / Nafarroako Gobernua
In the last years, many topographic correction (TOC) methods have been proposed to correct the illumination differences between the areas observed by optical remote sensors. Although the available number of TOC methods is high, the evaluation of their performance generally relies on the existence of precise land-cover information, and a standardized and objective evaluation procedure has not been proposed yet. In this paper, we propose an objective procedure to assess the accuracy of these TOC methods on the basis of simulated scenes, i.e., synthetically generated images. These images represent the radiance an optical sensor would receive under specific geometric and temporal acquisition conditions and assuming a certain land-cover type. A simplified method for creating synthetic images using the stateof- the-art irradiance models is proposed, both considering the real topography of a certain area [synthetic real (SR) image] or considering the relief of this area as being completely flat [synthetic horizontal image (SH)]. The comparison between the corrected image obtained by applying a TOC method to the SR and SH images of the same area, allows assessing the performance of each TOC algorithm. This comparison is quantitatively carried out using the structural similarity index. The proposed TOC evaluation procedure is applied to a specific case study in northern Spain to explain its implementation and demonstrate its potential. The procedure proposed in this paper could be also used to assess the behavior of TOC methods operating under different scenarios considering diverse topographic, geometrical, and temporal acquisition configurations.
Open Access
Proposal and evaluation of typical illuminance year (TIY) generation procedures from illuminance or irradiance data for daylight assessment in the long term
(Elsevier, 2020) García Ruiz, Ignacio; Blas Corral, María Ángeles de; Torres Escribano, José Luis; Ingeniaritza; Institute of Smart Cities - ISC; Ingeniería; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
When assessing the long-term daylight availability or the performance of natural lighting systems in a given location, it is necessary to have representative data of local daylight conditions. The use of a daylight test reference year (TRY) becomes a good option in these cases. This paper proposes and evaluates a procedure for the generation of a typical illuminance year (TIY) considering illuminance as the only variable for selecting the typical periods that make up the reference year. Two versions of TIY are presented, one composed of 12 typical months selected from the series of observations and another composed of 365 typical days. Each of these versions is used to obtain a global illuminance TIY (TGIY) and a diffuse illuminance TIY (TDIY) from a 27-year dataset corresponding to the Vaulx-en-Velin station (France). Furthermore, 12 luminous efficacy models have been evaluated in order to obtain a TIY from a TRY generated from irradiance data when no illuminance data are available. Thus, a global luminous efficacy model and a diffuse model are selected after benchmarking different models, considering both their original coefficients and those adjusted to local conditions. The results reveal that the monthly version of the TGIY and the daily version of the TDIY show the best overall fit to the long-term dataset. TIYs obtained from illuminance data are also observed to be statistically indistinguishable from those obtained after applying a luminous efficacy model to an irradiance-based TRY.
Open Access
Multitemporal evaluation of topographic correction algorithms using synthetic images
(SPIE, 2012) Sola Torralba, Ion; Álvarez Mozos, Jesús; González de Audícana Amenábar, María; Torres Escribano, José Luis; Proyectos e Ingeniería Rural; Landa Ingeniaritza eta Proiektuak
Land cover classification and quantitative analysis of multispectral data in mountainous regions is considerably hampered by the influence of topography on the spectral response pattern. In the last years, different topographic correction (TOC) algorithms have been proposed to correct illumination differences between sunny and shaded areas observed by optical remote sensors. Although the available number of TOC methods is high, the evaluation of their performance usually relies on the existence of precise land cover information, and a standardised and objective evaluation procedure has not been proposed yet. Besides, previous TOC assessment studies only considered a limited set of illumination conditions, normally assuming favourable illumination conditions. This paper presents a multitemporal evaluation of TOC methods based on synthetically generated images in order to evaluate the influence of solar angles on the performance of TOC methods. These synthetic images represent the radiance an optical sensor would receive under specific geometric and temporal acquisition conditions and assuming a certain land-cover type. A method for creating synthetic images using state-of-the-art irradiance models has been tested for different periods of the year, which entails a variety of solar angles. Considering the real topography of a specific area a Synthetic Real image (SR) is obtained, and considering the relief of this area as being completely flat a Synthetic Horizontal image (SH) is obtained. The comparison between corrected image obtained applying a TOC method to SR image and SH image of the same area, i.e. considered the ideal correction, allows assessing the performance of each TOC algorithm.
Open Access
Analytical expressions for estimating sky diffuse irradiance and illuminance on tilted planes for the CIE standard general skies
(Elsevier, 2021) Torres Escribano, José Luis; García Ruiz, Ignacio; Ingeniaritza; Institute of Smart Cities - ISC; Ingeniería
This work proposes a set of analytical expressions for the calculation of the relationship between sky diffuse illuminance on a tilted plane and horizontal plane corresponding to the 15 ISO/CIE standard sky types. Given the parallelism in the angular distribution of sky diffuse radiance and luminance, these expressions can also be used to calculate the diffuse sky irradiance on an inclined plane. The proposed analytical expressions are obtained by adjusting the results of a numerical calculation whose methodology is described in detail in the paper. The use of these analytical expressions significantly reduces the calculation time. It is verified that the relative root-mean-square errors obtained with the analytical expressions are small compared with the use of numerical calculation, ranging from 0.03% to 4.09%, and with a tendency to increase with clear skies and high solar zenith angles.
Open Access
Estimation of the solar thermal power generation potential in Pamplona (northern Spain)
(Universidad Carlos III, 2022) García Ruiz, Ignacio; Prieto Cobo, Eduardo; Torres Escribano, José Luis; Ingeniería; Ingeniaritza; Institute of Smart Cities - ISC
In this work, an analysis of the potential of the city of Pamplona to produce solar thermal energy was carried out, according to the solar radiation received. As a result, for each residential, industrial, or service rooftop, information was provided on (1) the area available for thermal installation, (2) the solar thermal installation capacity and (3) the monthly and annual thermal energy generation potential. It was found that, if all suitable areas of the city are used, it would be possible to achieve an annual total solar thermal energy production of 1197.69 GWh. If solar energy supply and thermal demand were perfectly coupled over time, it would be possible to cover 99.1% of Pamplona's thermal energy demand.