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Sáenz Gamasa, Carlos

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https://academica-e.unavarra.es/handle/2454/49935

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Sáenz Gamasa

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Carlos

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Ciencias

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InaMat2. Instituto de Investigación en Materiales Avanzados y Matemáticas

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0000-0002-6488-7750

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  • Thumbnail Image
    PublicationOpen Access
    Diffuse irradiance on tilted planes in urban environments: evaluation of models modified with sky and circumsolar view factors
    (Elsevier, 2021) García Ruiz, Ignacio; Blas Corral, María Ángeles de; Hernández Salueña, Begoña; Sáenz Gamasa, Carlos; Torres Escribano, José Luis; Ingeniaritza; Zientziak; Institute of Smart Cities - ISC; Institute for Advanced Materials and Mathematics - INAMAT2; Ingeniería; Ciencias
    Numerous studies have analyzed existing irradiance models for estimating sky diffuse irradiance on tilted planes. However, few have evaluated the suitability of these models for estimating irradiance in obstructed environments, specifically considering the effects of obstacles. In this study, three irradiance models —one of them with five variants— for estimating diffuse irradiance on tilted planes located in urban environments were evaluated. All models have been adapted to consider the effect of an urban canyon on the diffuse irradiance received on a tilted plane through the sky view factor and the circumsolar view factor. All the models were evaluated against the diffuse irradiance values obtained by the ISO 15469:2004(E)/CIE S 011/E:2003 angular distribution model. Therefore, it was necessary to determine the standard sky type corresponding to each record of the measurements performed by a sky scanner at the radiometric station of UPNA (Spain). A total of 4,864 scenarios were considered to occur from the combination of different orientations and inclinations of the plane, and different orientations and aspect ratios of the urban canyon. The results revealed that the Perez model considering a 35° half-angle circumsolar region has the best performance, followed by the Perez model considering a 45° half-angle circumsolar region.
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    PublicationOpen Access
    Evaluation of two procedures for selecting the CIE standard sky type using high dynamic range images
    (International Solar Energy Society, 2019) García Ruiz, Ignacio; Blas Corral, María Ángeles de; Torres Escribano, José Luis; Hernández Salueña, Begoña; Sáenz Gamasa, Carlos; Ormazábal Pagola, Mikel; Ingeniería; Ingeniaritza; Ciencias; Zientziak; Gobierno de Navarra / Nafarroako Gobernua
    The characterization of sky conditions according to the CIE Standard General Sky classification requires knowledge of diffuse luminance angular distribution in the sky vault. This variable is usually measured by sky scanners. However, commercial sky scanners have different drawbacks related to their resolution and measurement time. An alternative to these devices is the use of sky images captured with a digital camera equipped with a fisheye lens. The range of luminances that may occur in the sky makes it necessary to use high dynamic range (HDR) images obtained by the fusion of a series of low dynamic range (LDR) images. Two procedures for the characterization of sky conditions according to the CIE standard using HDR images have been applied and evaluated.
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    PublicationEmbargo
    CIELAB color paths during meat shelf life
    (Elsevier, 2019) Hernández Salueña, Begoña; Sáenz Gamasa, Carlos; Diñeiro Rubial, José Manuel; Alberdi Odriozola, Coro; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Ciencias
    Meat color evolution from freshly cut to beyond shelf life, up to 40% of metmyoglobin, has been theoretically modeled using the Kubelka-Munk theory and a set of measured reference reflectance spectra of deoxymyoglobin, oxymyoglobin and metmyoglobin. Color evolution depicts characteristic color paths in CIELAB color space. During oxidation the model explains the approximately constancy of L*, b* and hab, with variations typically hidden by sample dispersion, and the special significance of a* and C* in relation with metmyoglobin formation. CIELAB ΔE* color difference and the reflectance ratio R630/R580 are even better indicators of metmyoglobin changes during oxidation. The role of a*, C*, ΔE* and R630/R580 and their relationship during oxidation is a normal feature in the model with quantitative predictions in general agreement with literature. Results further emphasize the dangers of reporting color coordinates in different illuminants.
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    PublicationOpen 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.
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    PublicationOpen Access
    High power illumination system for uniform, isotropic and real time controlled irradiance in photoactivated processes research
    (Elsevier, 2024) Sáenz Gamasa, Carlos; Hernández Salueña, Begoña; Sanz Carrillo, Diego; Pellejero, Ismael; Gandía Pascual, Luis; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2
    In the study of photocatalytic and photoactivated processes and devices a tight control on the illumination conditions is mandatory. The practical challenges in the determination of the necessary photonic quantities pose serious difficulties in the characterization of catalytic performance and reactor designs and configurations, compromising an effective comparison between different experiments. To overcome these limitations, we have designed and constructed a new illumination system based in the concept of the integrating sphere (IS). The system provides uniform and isotropic illumination on the sample, either in batch or continuous flow modes, being these characteristics independent of the sample geometry. It allows direct, non-contact and real time determination of the photonic quantities as well as versatile control on the irradiance values and its spectral characteristics. It can be also scaled up to admit samples of different sizes without affecting its operational behaviour. The performance of the IS system has been determined in comparison with a second illumination system, mounted on an optical bench, that provides quasi-parallel beam (QPB) nearly uniform illumination in tightly controlled conditions. System performance is studied using three sample geometries: a standard quartz cuvette, a thin straight tube and a microreactor by means of potassium ferrioxalate actinometry. Results indicate that the illumination geometry and the angular distribution of the incoming light greatly affect the absorption at the sample. The sample light absorption efficiency can be obtained with statistical uncertainties of about 3% and in very good agreement with theoretical estimations.
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    PublicationOpen 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.
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    PublicationEmbargo
    Negative reflection, negative refraction and ray displacements in biaxial absorbing media, In4Se3
    (Taylor & Francis, 2019) Alberdi Odriozola, Coro; Diñeiro Rubial, José Manuel; Hernández Salueña, Begoña; Sáenz Gamasa, Carlos; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Ciencias
    We show the existence of negative reflection and negative refraction in a slab of biaxial absorbing medium In 4Se3 placed between two isotropic media. We find the limiting angle of incidence in the slab for these phenomena to occur and its dependence with the orientation of the crystal axes. We analyze, both in reflection and refraction, the displacement of the ray with respect to the incident one at the output of the slab, finding a potential measure to experimentally study this effect.