Publication list

Peer reviewed articles and book chapters

"And if my poor talents, my little experience of the present and insufficient study of the past, should make the result of my labors defective and of little utility, I shall at least have shown the way to others, who will carry out my views with greater ability, eloquence, and judgment, so that if I do not merit praise, I ought at least not to incur censure."

-- Niccolo Machiavelli, Discourses on Livy, 1531.

· A. Delgado-Bonal and A. Marshak, Approximate Entropy and Sample Entropy: A Comprehensive Tutorial, Entropy, 21(6), 541, (2019) doi:10.3390/e21060541 - PDF - .bib

· A. Delgado-Bonal, Entropy of radiation: the unseen side of light, Scientific Reports, 7, 1642, (2017) doi:10.1038/s41598-017-01622-6 - PDF - .bib

· A. Delgado-Bonal and F.J. Martín-Torres, Human vision is determined based on information theory, Scientific Reports, 6, 36038, (2016) doi:10.1038/srep36038 - PDF - .bib

· A. Delgado-Bonal, M.-P. Zorzano and F.J. Martín-Torres, Martian Top of the Atmosphere 10-to 420 nm spectral irradiance database and forecast for solar cycle 24, Solar Energy, Vol. 134, pp. 228-325, (2016) doi:10.1016/j.solener.2016.05.004 - PDF - .bib

· A. Delgado-Bonal, F.J. Martín-Torres, S. Vázquez-Martín, M.-P. Zorzano, Solar and wind exergy potentials for Mars, Energy, Vol. 102, pp. 550-558, (2016) doi:10.1016/ - PDF - .bib

· A. Delgado-Bonal and F.J. Martín-Torres, Solar Cell Temperature on Mars, Solar Energy, Vol. 118, pp. 74-79, (2015) doi:10.1016/j.solener.2015.04.035 - PDF - .bib

· A. Delgado-Bonal and F.J. Martín-Torres, Evaluation of the Mars atmospheric chemical entropy production, Entropy, Vol. 17, pp. 5047-5062, (2015) doi:10.3390/e17075047 - PDF - .bib

· A. Delgado-Bonal and F.J. Martín-Torres, A Mathematic Approach to Nitrogen Fixation Through Earth History, in: The Early Evolution of the Atmospheres of Terrestrial Planets, Springer, Vol. 35, pp. 23-31, (2013) doi:10.1007/978-1-4614-5191-4_3 - PDF - .bib

Recent Papers

May 2019

Approximate Entropy and Sample Entropy: A Comprehensive Tutorial


Approximate Entropy and Sample Entropy are two algorithms for determining the regularity of series of data based on the existence of patterns. Despite their similarities, the theoretical ideas behind those techniques are different but usually ignored. This paper aims to be a complete guideline of the theory and application of the algorithms, intended to explain their characteristics in detail to researchers from different fields. While initially developed for physiological applications, both algorithms have been used in other fields such as medicine, telecommunications, economics or Earth sciences. In this paper, we explain the theoretical aspects involving Information Theory and Chaos Theory, provide simple source codes for their computation, and illustrate the techniques with a step by step example of how to use the algorithms properly. This paper is not intended to be an exhaustive review of all previous applications of the algorithms but rather a comprehensive tutorial where no previous knowledge is required to understand the methodology. doi:10.3390/e21060541 - PDF - .bib

Nov 2016

Human vision is determined based on information theory

Scientific Reports

It is commonly accepted that the evolution of the human eye has been driven by the maximum intensity of the radiation emitted by the Sun. However, the interpretation of the surrounding environment is constrained not only by the amount of energy received but also by the information content of the radiation. Information is related to entropy rather than energy. The human brain follows Bayesian statistical inference for the interpretation of visual space. The maximization of information occurs in the process of maximizing the entropy. Here, we show that the photopic and scotopic vision absorption peaks in humans are determined not only by the intensity but also by the entropy of radiation. We suggest that through the course of evolution, the human eye has not adapted only to the maximum intensity or to the maximum information but to the optimal wavelength for obtaining information. On Earth, the optimal wavelengths for photopic and scotopic vision are 555 nm and 508 nm, respectively, as inferred experimentally. These optimal wavelengths are determined by the temperature of the star (in this case, the Sun) and by the atmospheric composition. doi:10.1038/srep36038 PDF - .bib

Featured article

May 2017

Entropy of radiation: the unseen side of light

· A. Delgado-Bonal - Scientific Reports

entropy ratio

Despite the fact that 2015 was the international year of light, no mention was made of the fact that radiation contains entropy as well as energy, with different spectral distributions. Whereas the energy function has been vastly studied, the radiation entropy distribution has not been analysed at the same speed. The Mode of the energy distribution is well known -Wien's law- and Planck's law has been analytically integrated recently, but no similar advances have been made for the entropy. This paper focuses on the characterization of the entropy of radiation distribution from an statistical perspective, obtaining a Wien's like law for the Mode and integrating the entropy for the Median and the Mean in polylogarithms, and calculating the Variance, Skewness and Kurtosis of the function. Once these features are known, the increasing importance of radiation entropy analysis is evidenced in three different interdisciplinary applications: defining and determining the second law Photosynthetically Active Radiation (PAR) region efficiency, measuring the entropy production in the Earth's atmosphere, and showing how human vision evolution was driven by the entropy content in radiation.
doi:10.1038/s41598-017-01622-6 PDF - .bib