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The influence that parameters crookedness and taper have on the stack volume was analyzed by using a 3D-simulation model in this study. To do so, log length, diameters at the midpoint and both ends, crookedness, bark thickness, taper and ovality were measured in 1000 logs of Scots pine. From this database, several data sets with different proportions of crooked and tapered logs in stack as well as with different degrees of taper and crookedness were created and taken as basis to simulate the stacks and carry out the analysis. The results show how the variation of these parameters influences the stack volume and provide their volume variation grades. These rates of variation were compared with measurement guidelines of some countries and previous research works. In conclusion, the parameters crookedness and taper influence the stack volume to a considerable extent. Specifically, the stack volume is increased as the crookedness degree or the proportion of crooked logs increases. In contrast, the stack volume is reduced as the taper degree or the proportion of tapered logs increases. Furthermore, the results demonstrate the capability of this simulation model to provide accurate results which can serve as a basis for future studies.
Comparison of different approaches to estimate bark volume of industrial wood at disc and log scale
(2021)
Within the wood supply chain, the measurement of roundwood plays a key role due to its high economic impact. While wood industry mainly processes the solid wood, the bark mostly remains as an industrial by-product. In Central Europe, it is common that the wood is sold over bark but that the price is calculated on a timber volume under bark. However, logs are often measured as stacks and, thus, the volume includes not only the solid wood content but also the bark portion. Mostly, the deduction factors used to estimate the solid wood content are based on bark thickness. The aim of this study was to compare the estimation of bark volume from scaling formulae with the real bark volume, obtained by xylometric technique. Moreover, the measurements were performed using logs under practice conditions and using discs under laboratory conditions. The mean bark volume was 6.9 dm3 and 26.4 cm3 for the Norway spruce logs and the Scots pine discs respectively. Whereas the results showed good performances regarding the root mean square error, the coefficient of determination (R2) and the mean absolute error for the volume estimation of the total volume of discs and logs (over bark), the performances were much lower for the bark volume estimations only.
In terms of assessing economic impact, one of the most important elements in the wood supply chain is the measurement of round wood. Besides the one-by-one measurement of logs, logs are often measured when stacked at the forest road. The gross stacked volume includes the volume of the wood, bark and airspace and is widely used for industrial wood assortments. The increasing international attention given to photo-optical measurement systems for portable devices is due to
their simplicity of use and efficiency. The aim of this study was to compare the gross volumes of
hardwood log stacks measured using one widespread photo-optical app with two manual section-wise volume estimations of log stacks based on the German framework agreement for timber trade (RVR). The manual volume estimations were done starting from the left (RVRleft) and right (RVRright) sides of the log stacks. The results showed an average deviation of the photo-optical gross volume estimation in comparison to the manual estimation of –2.09% (RVRleft) and –3.66% (RVRright) while the deviation between RVRleft and RVRright was +2.54%. However, the log stack
gross volume had a highly significant effect on the deviation and better accuracy with smaller
deviation were reached for larger log stacks. Moreover, results indicated that the gross volume estimations of higher quality log stacks were closer for the three analyzed methods compared to estimations of poor-quality log stacks.
Bark characteristics are not only used in the forest-wood supply chain, for example to calculate standing volumes, but also to transform wood volumes and masses. In this study, bark thickness, bark volume and bark mass were analyzed on the basis of 150 Scots pine discs, with a mean diameter of 13 cm. The mean double bark thickness was 3.02 mm, the mean bark volume proportion was 5.6% and mean bark mass proportion was 3.3%. Bark proportions were significantly affected by the log-specific variables ‘diameter over bark’, ‘proportion of bark damage’ and ‘double bark thickness’.
The accurate estimation of timber volume is of the utmost importance. For industrial timber, the volume is often estimated as stacked cubic meters. In addition to manual measurements, volume estimation is possible with photo-optical systems. Over 100 piles of industrial timber of broadleaved tree species were analyzed. In the study, a standard manual measurement method for the estimation of wood pile volumes was compared with a smartphone based photo-optical application for the determination of woodpile volume. Mean gross volume of the piles was approximately 56 m3 and mean width of piles was 9.43 m. A strong correlation was found between the manual measurements and the photo-optical measurement. However, volume estimation of large volume piles seems to perform better in comparison to piles with small volumes. Further research is needed to determine the effects of variables such as log quality or quality of pile on volume estimation accuracy.
The variation of wood species processed in sawmills in developing countries generates composite waste which presents treatment challenges due to a lack of understanding of their physicochemical characteristics for proper planning for clean energy generation. Most of the waste is discarded or burnt openly which releases harmful gases into the environment. This study investigated the physicochemical characteristics of mixed sawdust generated from five wood species generated at a Ghanaian sawmill in Oforikrom Municipality for improving waste treatment. The particle size distribution (PSD), bulk density, proximate and ultimate values, thermogravimetric analysis (TGA) and structural analysis were used to characterize the composite sawdust for briquetting and gasification purposes. It was found that the net heating value (17.46 MJ/kg), some proximate and ultimate values meet briquette standard but high percentages of ash (2.95%), moisture (41.48%) and the possibility of nitrogen oxides emissions were notable challenges. PSD resulted in different high fine fractions which are unsuitable for densification. The increase of sieving amplitudes at 30, 50 and 80 rpm generated an average increase in sieve efficiency of fines by 4.22%. Mixing of fines (42.38–46.6%) and optimum particle size (53.40–57.62%) fractions was suggested as the best approach to enhance briquette density and durability. The FTIR spectra showed a range of peaks such as 1734.46 cm−1, 1620.48 cm−1, 1506.50 cm−1, 1462.02 cm−1, 1420.32 cm−1 etc. for functional groups identification. Composite sawdust spectra showed high absorbance with no shift of wavenumbers compared with temperate woods, however, it deviated massively when compared with industrial cellulose and organosolv lignin. TGA indicated that exact mixed wood pyrolysis temperatures, volatile and biochar fractions will always depend on sample compositions. The increase in heating rates yielded little significance to volatiles and char increments. Collection of clean sawdust and rooftop drying were recommended as a way of enhancing sawdust properties. Composite sawdust has a promising potential to support Ghana's activities for meeting the renewable energy generation targets. The understanding of these potential assessments is significant to boost the local municipality energy supply.
The rational use of natural resources is essential for sustainable development. The use of environmentally friendly raw materials, which has minimal environmental impact in its processing, is necessity today. The ecological value of the black locust wood is analyzed based on the study of its use and on the markets in Germany. It is a valuable tree like tropical tree species. It can be obtained by environmentally friendly procurement methods. Therefore, the possibility of growing this invasive species of plants on reclaimed coal-mining dumps under environmental monitoring has been studied. The plantations peculiarities of the black locust plant in the Northeast Lowland of Germany were investigated. The structure, properties of the work wood, and its possibilities of use were analyzed. The principles of sorting and corresponding quality criteria for the wood of the work were considered. We made comparison of the markets in Brandenburg (Germany) and Hungary. Measures to increase the use of work are suggested. The disrupted lands of the Male Polissya are considered as reserve territories for receiving ecological wood of the black locust. It is environmentally justifiable to set aside for this affected areas of coal mining in favourable forest areas. The phytomeliorative properties of black locust tree make it a promising species for afforestation of newly formed ecotopes with wide ecological amplitude in Male Polissya conditions. The creation of reclamation layers of loose soils is a prerequisite for ensuring their uniform growth and development in the conditions of coal-mining dumps. The distribution of the main taxation indices of the black locust stands on the new soils depends on their physicochemical properties and on the microclimatic features of the dumps. This causes differences in the growth and development of black locust plantations, effects on the quality of the wood of black locust and determines the ways of its possible use. Land reclamation effect of black locust plantations is associated with production effect. Simultaneously with receiving the black locust wood, the environmental situation will be getting better, because black locust can protect soil from erosion due to its root system. This is especially important in times of climate change. Black locust plantations on reclaimed coal-mining dumps can be considered as an additional source of the biologically stable wood.
The quantification of the solid wood content in a wood stack has been an object of investigation since the 18th century. Particularly, the log parameters exert a considerable influence on the volume of the stack, such as (1) the log midpoint diameter, (2) average bark thickness, (3) crookedness, and (4) log taper. Although many of these parameters have already been studied and some are already considered in many countries when measuring wood stacks, their influence has not been analyzed individually so far since a broad statistical database is needed and the data collection is very costly. Consequently, a 3D-simulation model was developed based on a cross-platform game engine. This model generates virtual wood stacks based on a data set of logs which are defined by the user. The simulation of a stack can be done in a few seconds only and each stack generated can be visualized once all iterations are done. The simulation results are the stacked cubic volume, solid wood cubic volume, and the respective conversion factors. The model, fed with both real data and user-defined data, allows for a detailed analysis of the effect of each parameter on the results, as the user can vary their values discretionary. To obtain the first results from real data, 1000 logs of Scots pine (Pinus sylvestris L.) were measured. The first simulations based on these data show reliable results and it is possible to quantify the influence of the proportion of crooked wood in a pile on the stack volume and the conversion factor. In addition, the results are highly in line with the real trials that have already been performed in parallel. A further scientific evaluation and statistical analysis will be done in a second study phase. However, the model already provides a reasonable tool that is easy to apply for the forest and wood industry in order to make the most accurate estimate possible of the solid wood content in a wood pile.