## 3 Results and Discussion  
The obtained results were referred to the characteristics of the strands, the characteristics of the OSB boards and the correlations between them, depending on the four wood species used (poplar, willow, pine, and spruce). For the characteristics of the strands, all the dimensional characteristics of the measured strands made with the electronic callipers were put in the Excel tables, and then the global characteristics were calculated. They were recorded starting with the dimensions (l, w, and t) and ending with the characteristic of thinness. Regarding the slenderness ratio, a high variability from 75.1 to 250.2 were found, while the thinness characteristic has lower values (2.3-6.86) and it is more comprehensive than the slenderness ratio. From the analysis of the table values, it is observed that the surface of the strands is very different from one strand to another, with differences of over 196%. For surface calculating of each strand, the surface of the edges was neglected, that was in fact very small. For example, in the case of poplar strand, the surface of the edges was 3.04 cm\({}^{2}\), which means less than 5% of the total surface of the strand, and for willow  
Figure 5: Strand size for OSB boards. strands, the ratio is even smaller due to the smaller thickness of the strand. The data for all the sample of strands were summarized in Table 1.  
As shown in Table 1, on the whole, the characteristics of the strands are different and from these values it is very difficult to draw a conclusion. However, it is clearly observed that willow strands have supremacy in terms of the length, width, and thickness of the strand; the specific surface; and the characteristic of thinness. To perform a hierarchy of the quality of the woody species, a sorting algorithm is considered applying a maximum score of four points for the woody species that holds the first place, three points for the second place, two points for the third place, and one point for the last place. It is also considered that there are six criteria, eliminating the equivalent diameter which exclusively depends on the width and thickness of the strands. Summing the obtained score by each species strands, it is obtained the hierarchy from Figure 6.  
Because there is a great variability of the surface of the strands (Table 1) and the average of these dimensions does not offer a clear separation of the species, but mainly because the dimensions of the strands depend on the cutting type, the settings of the machine and the degree of cutting wear, it was necessary to create a theoretical model to obtain the specific surface of the strands. The modelling of the specific surface of the strands started from the cut species and its average thickness. For this, it started from 100 g of strands, equivalent to 100 g of wood of each analysed species (evidenced by the density at 10% moisture content of each species). The density of the wood of the species used was: spruce--405 kg/m\({}^{3}\), pine--443 kg/m\({}^{3}\), poplar--452 kg/m\({}^{3}\), and willow--478 kg/m\({}^{3}\). It was then considered that each wood piece of 10 \(\times\) 10 mm was sliced with thicknesses from 0.1 mm to 2 mm, obtaining each time a new