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Articles by Dominik Röser

Category : Research article

article id 1342, category Research article

Blas Mola-Yudego, Gianni Picchi, Dominik Röser, Raffaele Spinelli. (2015). Assessing chipper productivity and operator effects in forest biomass operations. Silva Fennica vol. 49 no. 5 article id 1342. https://doi.org/10.14214/sf.1342

Keywords: mixed models; efficiency; comminution; operator effect; raw material supply; wood chippers

Highlights: A model is constructed to assess the productivity in chipping of wood biomass at roadside; The data includes 172 trials and 67 operators in Italy; The operator effect was included in a mixed model approach; The R2 were 0.76 (fixed part) and 0.88 (incl. operator effects).

Abstract | Full text in HTML | Full text in PDF | Author Info

The present research focuses on the productivity of energy wood chipping operations at several sites in Italy. The aim was to assess the productivity and specifically the effect attributed to the operator in the chipping of wood biomass. The research included 172 trials involving 67 operators across the country that were analysed using a mixed model approach, in order to assess productivity, and to isolate the operator effect from other potential variables. The model was constructed using different predictors aiming to explain the variability due to the machines and the raw-materials. The final model included the average piece weight of raw material chipped as well as the power of the machine. The coefficients of determination (R²) were 0.76 for the fixed part of the model, and 0.88 when the effects due to the operators were included. The operators’ performance compared to their peers was established, and it was compared to a subjective classification based on the operator’s previous experience. The results of this study can help to the planning and logistics of raw material supply for bioenergy, as well as to a more effective training of future forest operators.

Mola-Yudego, School of Forest Sciences, University of Eastern Finland, P.O. Box 111, FI-80101 Joensuu, Finland; NIBIO Norwegian Institute of Bioeconomy Research, P.O. Box 115, 1431 Ås, Norway http://orcid.org/0000-0003-0286-0170 E-mail: blas.mola@uef.fi
Picchi, CNR IVALSA, Via Madonna del Piano 10, I-50019 Sesto Fiorentino, Italy E-mail: picchi@ivalsa.cnr.it
Röser, Forest Feedstocks Group, FPInnovations, Vancouver, British Columbia, Canada E-mail: dominik.roser@fpinnovations.ca
Spinelli, CNR IVALSA, Via Madonna del Piano 10, I-50019 Sesto Fiorentino, Italy E-mail: spinelli@ivalsa.cnr.it

article id 124, category Research article

Johannes Windisch, Lauri Sikanen, Dominik Röser, David Gritten. (2010). Supply chain management applications for forest fuel procurement – cost or benefit? Silva Fennica vol. 44 no. 5 article id 124. https://doi.org/10.14214/sf.124

Keywords: logistics; forest fuel; supply chain management; cost-benefit analysis

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It is commonly agreed that logistics is very demanding in forest fuel business. Even though logistics and supply chain management (SCM) tools already have found their way into forestry business, for example, in roundwood operations, they are not yet very widespread in the field of forest fuel procurement. The present study investigates if modern supply chain management applications are capable of increasing the profitability of forest fuel procurement operations. Since margins are low, decreasing the provision costs could boost wood-based bioenergy business. The study is based on the investigation of two Finnish forest owners associations (FOA) involved in forest fuel procurement using a modern SCM tool. The investigation is done by cost-benefit analysis (CBA) using the net present value (NPV) methodology to determine the profitability. According to the estimates made by the staff, which are based on data such as work time records and delivery notes from before and after introduction of the new system, in both FOAs, the benefits far outweigh the costs over a considered timespan of ten years. However, the amount of the NPV varied significantly. For FOA1, with an annual chip production of 150 000 loose m3, the NPV is 212 739 euro, while for FOA2, with an annual chip production of 37 000 loose m3, the NPV is 969 841 euro. Even if the NPV of FOA2 seems to be very high, the profitability of SCM tools in forest fuel procurement is clearly demonstrated. Additionally, the results indicate that a considerable cost saving potential in forest fuel procurement is attainable through improving work flows and thus reduce the work input.

Windisch, Finnish Forest Research Institute, Joensuu Research Unit, Yliopistokatu 6, P.O. Box 68, FI-80101 Joensuu, Finland E-mail: johannes.windisch@metla.fi
Sikanen, University of Eastern Finland, School of Forest Science, Yliopistokatu 7, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: ls@nn.fi
Röser, Finnish Forest Research Institute, Joensuu Research Unit, Yliopistokatu 6, P.O. Box 68, FI-80101 Joensuu, Finland E-mail: dr@nn.fi
Gritten, University of Eastern Finland, School of Forest Science, Yliopistokatu 7, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: dg@nn.fi

article id 264, category Research article

Yrjö Nuutinen, Kari Väätäinen, Jaakko Heinonen, Antti Asikainen, Dominik Röser. (2008). The accuracy of manually recorded time study data for harvester operation shown via simulator screen. Silva Fennica vol. 42 no. 1 article id 264. https://doi.org/10.14214/sf.264

Keywords: accuracy of timing; mixed effects models; time studies

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The aim of the study was to investigate the effect of work experience on the accuracy and variation of observers recording the operation time of a harvester. A simulated thinning operation using a harvester, shown as video via a television screen in laboratory conditions, was observed by 20 inexperienced students and 10 experienced work study researchers. All the observers timed the different work elements of the harvester work with special fieldwork timers. The duration of different work elements measured by the human observers were compared to the corresponding recordings by the harvester’s automated data collector. Although the inexperienced students made more measurement mistakes than the experienced researchers, the differences in measurement error averages were not statistically significant between the groups. However, the variances of tree specific errors were significantly higher in the measurements done by the students. As inexperienced recorders, the students were not able to properly record short work elements, which lasted a maximum of 4 seconds. Due to systematic measurement errors, there was a large variation in the timing structures of the work elements among all observers. Observers’ skills and experience seems to affect measurement accuracy and thus the derived results, especially in intensive time studies. Therefore, the recorder should receive detailed training and practical experience in timing of different work elements of forest operations. In the future, with the use of automated data collectors time studies with large, detailed and accurate data will be implemented. However, due to the varying timing conditions in the forest, manual data collection is still required because of its greater flexibility.

Nuutinen, Finnish Forest Research Institute, Joensuu Research Unit, P.O. Box 68, FI-80101 Joensuu, Finland E-mail: yrjo.nuutinen@metla.fi
Väätäinen, Finnish Forest Research Institute, Joensuu Research Unit, P.O. Box 68, FI-80101 Joensuu, Finland E-mail: kv@nn.fi
Heinonen, Finnish Forest Research Institute, Joensuu Research Unit, P.O. Box 68, FI-80101 Joensuu, Finland E-mail: jh@nn.fi
Asikainen, Finnish Forest Research Institute, Joensuu Research Unit, P.O. Box 68, FI-80101 Joensuu, Finland E-mail: aa@nn.fi
Röser, Finnish Forest Research Institute, Joensuu Research Unit, P.O. Box 68, FI-80101 Joensuu, Finland E-mail: dr@nn.fi

Category : Research note

article id 60, category Research note

Dominik Röser, Blas Mola-Yudego, Robert Prinz, Beatrice Emer, Lauri Sikanen. (2012). Chipping operations and efficiency in different operational environments. Silva Fennica vol. 46 no. 2 article id 60. https://doi.org/10.14214/sf.60

Keywords: wood-fuel logistics; forest machinery; bioenergy supply

Abstract | View details | Full text in PDF | Author Info

This research analyses the productivity of energy wood chipping operations at several sites in Austria and Finland. The aim of the work is to examine the differences in productivity and the effects of the operational environment for the chipping of bioenergy at the roadside. Furthermore, the study quantifies the effects of different variables such as forest energy assortments, tree species, sieve size and machines on the overall productivity of chipping. The results revealed that there are significant differences in the chipping productivity in Austria and Finland which are largely based on the use of different sieve sizes. Furthermore, the different operational environments in both countries, as well as the characteristics of the raw material also seem to have an effect on productivity. In order to improve the chipping productivity, particularly in Central European conditions, all relevant stakeholders need to work jointly to find solutions that will allow a greater variation of chip size. Furthermore, in the future more consideration has to be given to the close interlinkage between the chipper, crane and grapple. As a result, investments costs can be optimized and operational costs and stress on the machines reduced.

Röser, Finnish Forest Research Institute, P.O. Box 68, FI-80101 Joensuu, Finland E-mail: dominik.roser@metla.fi
Mola-Yudego, University of Eastern Finland, School of Forest Sciences, Joensuu, Finland E-mail: bmy@nn.fi
Prinz, Finnish Forest Research Institute, P.O. Box 68, FI-80101 Joensuu, Finland E-mail: rp@nn.fi
Emer, University of Padova, Department of Land, Agriculture and Forest Systems, Legnaro (PD), Italy E-mail: be@nn.it
Sikanen, University of Eastern Finland, School of Forest Sciences, Joensuu, Finland E-mail: ls@nn.fi

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