@article{deMiguelDiezGuiguePettenkoferetal.2022, author = {de Miguel-D{\´i}ez, Felipe and Guigue, Phillippe and Pettenkofer, Tim and Tolosana-Esteban, Eduardo and Purf{\"u}rst, Thomas and Cremer, Tobias}, title = {Development and evaluation of a novel 3D simulation software for modelling wood stacks}, series = {PLoS ONE}, journal = {PLoS ONE}, number = {17(3)}, issn = {1932-6203}, doi = {10.1371/journal.pone.0264414}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:eb1-opus-4472}, pages = {17}, year = {2022}, abstract = {Assessing the solid wood content is crucial when acquiring stacked roundwood. A frequently used method for this is to multiply determined conversion factors by the measured gross volume. However, the conversion factors are influenced by several log and stack parameters. Although these parameters have been identified and studied, their individual influence has not yet been analyzed using a broad statistical basis. This is due to the considerable financial resources that the data collection entails. To overcome this shortcoming, a 3D-simulation model was developed. It generates virtual wood stacks of randomized composition based on one individual data set of logs, which may be real or defined by the user. In this study, the development and evaluation of the simulation model are presented. The model was evaluated by conducting a sensitivity and a quantitative analysis of the simulation outcomes based on real measurements of 405 logs of Norway spruce and 20 stacks constituted with these. The results of the simulation outcomes revealed a small overestimation of the net volume of real stacks: by 1.2\% for net volume over bark and by 3.2\% for net volume under bark. Furthermore, according to the calculated mean bias error (MBE), the model underestimates the gross volume by 0.02\%. In addition, the results of the sensitivity analysis confirmed the capability of the model to adequately consider variations in the input parameters and to provide reliable outcomes.}, language = {en} } @article{deMiguelDiezPettenkoferWalloretal.2022, author = {de Miguel-D{\´i}ez, Felipe and Pettenkofer, Tim and Wallor, Evelyn and Tolosana-Esteban, Eduardo and Purf{\"u}rst, Thomas and Cremer, Tobias}, title = {Influence of log and stack parameters on the conversion factors for Norway Spruce wood stacks using a 3D simulation model}, series = {International Journal of Forest Engineering}, volume = {33}, journal = {International Journal of Forest Engineering}, number = {2}, publisher = {Taylor \& Francis}, issn = {1494-2119}, doi = {10.1080/14942119.2022.2038023}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:eb1-opus-4482}, pages = {119 -- 128}, year = {2022}, abstract = {One method for estimating the solid wood content in a stack involves using conversion factors and multiplying these by the measured gross volume. The conversion factors can vary depending on several log and stack parameters. The aim of this study was to analyze eleven parameters using a 3D simulation model based on 541 measured logs of Norway spruce. To this end, 50 data sets were created from measured logs, where the parameters of interest in this study (e.g., length, crookedness, taper …) were classified according to different ranges. After that, 64 runs of simulations were carried out. In each simulation run, 150 stacks were modeled. The simulation results were compared with previous studies and with the measurement guidelines of several countries. This analysis revealed that the parameters midpoint diameter, length, crookedness, delimbing quality and the proportion of moderately and highly crooked logs in a stack have a considerable influence on the conversion factors. Taper, proportion of butt logs in a stack and stack height have a modest effect as do the proportion of tapered and crooked logs for low and high taper and low crookedness. In contrast, ovality and the proportion of logs stacked in opposite directions have a marginal influence on the conversion factors. Based on findings from these analyses, the current measurement guidelines of different countries can now be adapted to achieve a higher degree of accuracy.}, language = {en} }