The Experts below are selected from a list of 228 Experts worldwide ranked by ideXlab platform

Mariano Sidrach-de-cardona - One of the best experts on this subject based on the ideXlab platform.

  • Using probabilistic finite automata to simulate hourly series of Global Radiation
    Solar Energy, 2003
    Co-Authors: Llanos Mora-lópez, Mariano Sidrach-de-cardona
    Abstract:

    Abstract A model to generate synthetic series of hourly exposure of Global Radiation is proposed. This model has been constructed using a machine learning approach. It is based on the use of a subclass of probabilistic finite automata which can be used for variable-order Markov processes. This model allows us to represent the different relationships and the representative information observed in the hourly series of Global Radiation; the variable-order Markov process can be used as a natural way to represent different types of days, and to take into account the “variable memory” of cloudiness. A method to generate new series of hourly Global Radiation, which incorporates the randomness observed in recorded series, is also proposed. As input data this method only uses the mean monthly value of the daily solar Global Radiation. We examine if the recorded and simulated series are similar. It can be concluded that both series have the same statistical properties.

  • A multivariate qualitative model for the prediction of daily Global Radiation from three hourly Global Radiation values
    Energy, 2001
    Co-Authors: Lourdes Ramirez, Ll. Mora-lópez, Mariano Sidrach-de-cardona
    Abstract:

    Abstract A new model for the prediction of daily Global Radiation using three hourly Radiation values is proposed. This model is obtained by multivariate regression analysis. The hourly clearness index and various qualitative variables are used as independent variables. The hourly values are obtained from net ground measures of hourly Global Radiation corresponding to the hours in which Meteosat secondary images are available over Europe. The qualitative variables allow us to include additional non-numerical information, specifically, the season of the year. The proposed model is the same for all the locations analysed. This model can be used for the prediction of daily Global Radiation based on hourly Global Radiation data obtained from satellite images.

  • Characterization and simulation of hourly exposure series of Global Radiation
    Solar Energy, 1997
    Co-Authors: Llanos Mora-lópez, Mariano Sidrach-de-cardona
    Abstract:

    A statistical model which captures the main features of hourly exposure series of Global Radiation is proposed. This model is used to obtain a procedure to generate Radiation series without imposing, a priori, any restriction on the form of the probability distribution function of the series. The statistical model was taken from the stationary stochastic processes theory. Data were obtained from ten different Spanish locations. As monthly hourly exposure series of Global Radiation are not stationary, they are modified in order to remove the observed trends. A multiplicative autoregressive moving average model with regular and seasonal components was used. It is statistically accepted that this is the true model which generates most of the analyzed sequences. However, the underlying parameters of the model vary from one location to another and from one month to another. Therefore, it is necessary to examine further the relationship between the parameters of the model and the available data from most locations.

Llanos Mora-lópez - One of the best experts on this subject based on the ideXlab platform.

  • Using probabilistic finite automata to simulate hourly series of Global Radiation
    Solar Energy, 2003
    Co-Authors: Llanos Mora-lópez, Mariano Sidrach-de-cardona
    Abstract:

    Abstract A model to generate synthetic series of hourly exposure of Global Radiation is proposed. This model has been constructed using a machine learning approach. It is based on the use of a subclass of probabilistic finite automata which can be used for variable-order Markov processes. This model allows us to represent the different relationships and the representative information observed in the hourly series of Global Radiation; the variable-order Markov process can be used as a natural way to represent different types of days, and to take into account the “variable memory” of cloudiness. A method to generate new series of hourly Global Radiation, which incorporates the randomness observed in recorded series, is also proposed. As input data this method only uses the mean monthly value of the daily solar Global Radiation. We examine if the recorded and simulated series are similar. It can be concluded that both series have the same statistical properties.

  • Characterization and simulation of hourly exposure series of Global Radiation
    Solar Energy, 1997
    Co-Authors: Llanos Mora-lópez, Mariano Sidrach-de-cardona
    Abstract:

    A statistical model which captures the main features of hourly exposure series of Global Radiation is proposed. This model is used to obtain a procedure to generate Radiation series without imposing, a priori, any restriction on the form of the probability distribution function of the series. The statistical model was taken from the stationary stochastic processes theory. Data were obtained from ten different Spanish locations. As monthly hourly exposure series of Global Radiation are not stationary, they are modified in order to remove the observed trends. A multiplicative autoregressive moving average model with regular and seasonal components was used. It is statistically accepted that this is the true model which generates most of the analyzed sequences. However, the underlying parameters of the model vary from one location to another and from one month to another. Therefore, it is necessary to examine further the relationship between the parameters of the model and the available data from most locations.

Miao Qi-lon - One of the best experts on this subject based on the ideXlab platform.

  • Characteristics of Global Radiation and Ultraviolet Radiation over Desert-oasis Transition Zone of the North Taklimakan Desert
    Journal of Desert Research, 2013
    Co-Authors: Miao Qi-lon
    Abstract:

    Based on solar Radiation measurement data from Xiaotang station over desert-oasis transition zone of the north Taklimakan Desert in 2011,the characteristics of Global Radiation and ultraviolet(UV)Radiation were analyzed.The result showed that monthly variation of Global Radiation and UV Radiation took on the same pattern.Annual total values of Global Radiation and UV Radiation were 5 441.31 MJ·m-2 and 242.62MJ·m-2,which were less than the annual total values of Global Radiation and UV Radiation in the Taklimakan desert hinterland by about 21%and 10%,respectively.The daily total values of Global Radiation and UV Radiation were 0.68 MJ·m-2 and 15.35 MJ·m-2,respectively.The maximum instantaneous Global Radiation(1 329.6 W·m-2)and UV Radiation(62.7 W·m-2)emerged in June.The subtractive effect of sand-dust storm on UV Radiation was very strong,and floating dust effect seemed to be relatively weak.The ratio of daily average UV Radiation to the daily average Global Radiation was 3.36%-7.25%,and the annual average ratio was 4.45%.

Manuel Collares-pereira - One of the best experts on this subject based on the ideXlab platform.

  • Statistical properties of hourly Global Radiation
    Solar Energy, 1992
    Co-Authors: R. Aguiar, Manuel Collares-pereira
    Abstract:

    Abstract The statistics of hourly Global Radiation are analysed for various climates and locations, at time scales ranging from one month to one hour. The probabilistic and sequential properties of the hourly clearness index kt are related with a variety of parameters, including the daily clearness index Kt and the solar altitude angle h, thereby displaying the nonstationary and time-inhomogeneous nature of hourly Radiation. Analytical expressions for the probability distribution of kt are proposed (truncated Gaussian functions depending on Kt and h). The results reported in this paper provide a deeper understanding of hourly solar Radiation statistics, and explain some of the features displayed by Radiation data at longer time scales. From the practical point of view they have implications, for example, for the construction of models for generating synthetic Radiation data, an important and often indispensable tool for designing and simulating solar systems.

Helga Kromp-kolb - One of the best experts on this subject based on the ideXlab platform.

  • Modelling Global Radiation in complex terrain: comparing two statistical approaches
    Agricultural and Forest Meteorology, 2000
    Co-Authors: Helfried Scheifinger, Helga Kromp-kolb
    Abstract:

    Two simple approaches for assessing Global Radiation in complex terrain are tested and compared. A parameterisation scheme for Global Radiation based on cloud cover observations was compared with interpolation of measured Global Radiation values from the Austrian climate observation network. Interpolation appears to be a useful method for a station density which has been available after 1992 in Austria (about 1000 km2/station). In that case interpolation is superior to parameterisation. The quality of interpolated data quickly drops with height and for elevations above 1500 m neither method delivers useful results.