L. García Esteban

Estimating the Uncertainty of a Multilayer Perceptron Using the Monte Carlo Method

Artificial neural networks have become a powerful modeling tool. However, although they obtain an output with very good accuracy, they provide no information about the uncertainty of the network or its coverage intervals. This study describes the application of the Monte Carlo method to obtain the output uncertainty and coverage intervals of a particular type of artificial neural network: the multilayer perceptron.

Wood anatomy of the genus Abies a revieW

The literature on the wood anatomy of the genus Abies is reviewed and discussed, and complemented with a detailed study of 33 species, 1 subspecies and 4 varieties. In general, the species studied do not show diagnostic interspecific differences, although it is possible to establish differences between groups of species using certain quantitative and qualitative features.The marginal axial parenchyma consisting of single cells and the ray parenchyma cells with distinctly pitted horizontal walls, nodular end walls and presence of indentures are constant for the genus, although these features also occur in the other genera of the Abietoideae. The absence of ray tracheids in Abies can be used to distinguish it from Cedrus and Tsuga, and the irregularly shaped parenchymatous marginal ray cells are only shared with Cedrus. The absence of resin canals enables Abies to be distinguished from very closely related genera such as Keteleeria and Nothotsuga. The crystals in the ray cells, taxodioid cross-field pitting and the warty layer in the tracheids can be regarded as diagnostic generic features.

Key to the identification of conifer woods at the level of species. European and north american regions

This work presents the first step to establish a identification key of world-wide conifer woods at the species level. The identification of 120 coniferous species of North America and Europe have been established. Traditional methods of preparation and microscopic woods description have been followed. The 93 traits used were grouped in six main types: 29 characters of the tracheids, eight characters of the longitudinal parenchyma, 37 characters of wood rays, seven characters of resin ducts, two macroscopic characters, and 10 characters related to the geographical distribution of the species. An open key has been obtained for the identification of the species based on these six groups of traits. This work constitutes one of the research lines of the Wood Techonology Department of the ETSI Montes in Madrid, and can be used by researches and users devoted to the international woods trade of protected species.