| 1. |
- Bergström, Dan, et al.
(författare)
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Skörd av skogsbränsle i förstagallringar
- 2010
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Efterfrågan på skogsbränslen ökar men någon större ökning av biprodukter från skogsindustrin kan man inte räkna med de kommande 10-20 åren. Detta innebär att konkurrensen om veden kommer att intensifieras och man ser idag möjligheter att skörda skogsbränslen från skogen, i såväl gallringar som föryngringsavverkningar. I Sverige utgör ogallrade skogar med en höjd under 15 m och ett biomassainnehåll mer än 30 ton torrsubstans (TS) per ha cirka 18,4% av den totala skogsmarksarealen. Den totala stående volymen på dessa arealer är cirka 258 miljoner ton TS varav 56% finns i Norrland. Den årliga avverkningspotentialen från dessa skogar ligger på ca 5 miljoner ton TS (ca 23 TWh) för landet som helhet. Vid en konventionell förstagallring tar man ut massaved (och ev. klentimmer) som gagnvirke där endast stammar med en brösthöjdsdiameter (dbh) över cirka 8 cm är kommersiellt gångbara. I tidiga förstagallringar får den konventionella gallringen höga avverkningskostnader på grund av beståndets låga medelstam (dbh < 12cm) och låg andel gagnvirke. Generellt när man apterar massaved i tidiga gallringar så kan cirka 20-30% av stamvedsvolymen inte användas pga för klena dimensioner. Denna volym tillsammans med trädets topp och grenar, lämnas outnyttjade i beståndet. Idag med en växande skogsbränslemarknad finns ett nytt sortiment som kan konkurrera med rundvirket i förstagallringar av stamrika, klena bestånd. Syftet med denna studie är att påvisa de mängder skogsbränsle som faller ut vid gallring av typiska klena, täta och normala gallringar i södra Sverige och att jämföra detta med rundvirkesutfallet som samma bestånd kan generera vad avser mängder och lönsamhet vid olika prisrelation mellan sortimenten. I utförda beräkningar har typbestånd använts. Ett relativt högt massavedspris och ett relativt lågt skogsbränslepris jämfört dagens prisnivåer har använts. Resultaten visar att skogsbränsle kan ge uppemot tre gånger högre bruttointäkt per hektar än massaved i ”klena” (dbh 9 cm) bestånd. Även i en mer normala förstagallring vad gäller stamdiametern (dbh 14 cm) ger skogsbränslet ca 13% högre bruttointäkt. I beräkningarna uppvisar skogsbränsle systemet ett avsevärt högre nettointäkt än massavedssystemet i det ”klena” beståndet. Författarna konkluderar att: • i tidiga/klena gallringar utgör den potentiella mängden massaved endast en liten del av den totala biomassan vilket också ger ett förhållandevis låg bruttointäkt jämfört med om hela biomassan skördas som skogsbränsle; • inte ens i ”normala” förstagallringar är bruttointäkten på massaveden högre än för skogsbränsle med dagens prisnivåer; • i klena” förstagallringar ger skogsbränsleskörd ett betydligt högre nettointäkt än motsvarande massavedsskörd; • om anpassad teknik för skörd och hantering av klena träd utvecklas kan stora mängder bränsle kostnadseffektivt skördas från de svenska ungskogarna. Det är inte något stort tekniksprång som behövs, och med kloka satsningar kan nya system realiseras inom kort tid
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| 2. |
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| 3. |
- Sängstuvall, Lars, et al.
(författare)
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Application of a primarily deductive framework describing time consumption for hauling of logs to road-side
- 2014
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Ingår i: Annals of Operations Research. - : Springer Science and Business Media LLC. - 0254-5330 .- 1572-9338. ; 219, s. 477-489
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Tidskriftsartikel (refereegranskat)abstract
- Forest management planning decisions are often based on the forest owner's goals, which typically focus on economic criteria. Logging operation work productivity functions are used when costing forest operations. These functions affect the conclusions drawn during forest management analyses because different logging environments give rise to different harvesting costs. When evaluating new combinations of machines and environments, there is generally a shortage of field data on productivity that can be examined in advance. We applied a previously published deductive framework describing time consumption in forwarding to known environments, in which field studies on forwarding have been conducted and for which extensive data are available. We then adapted the deductive framework to better reproduce the results obtained in the time studies. The deductive framework accurately reproduced the observed forwarding productivities; on average, the adaptation process improved the accuracy of this reproduction. However, it may also have reduced the accuracy of individual predictions. We conclude that the deductive framework can be used as a basis for constructing work productivity functions for forest management analyses, and can serve as a foundation when constructing new productivity functions based on time study results to use when pricing forwarding.
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| 4. |
- Sängstuvall, Lars, et al.
(författare)
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Simulation of harvester productivity in selective and boom-corridor thinning of young forests
- 2012
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Ingår i: Scandinavian Journal of Forest Research. - : Informa UK Limited. - 0282-7581 .- 1651-1891. ; 27, s. 56-73
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Tidskriftsartikel (refereegranskat)abstract
- Forest management practices may change in the future, due to increases in the extraction of forest fuel in first thinnings. Simulation models can be used to aid in developing new harvesting systems. We used such an approach to assess the productivity of innovative systems in various thinnings of young stands with wide ranges of mean breast height diameter (1.5 - 15.6 cm), stems per hectare (1000 - 19,100), and mean height (2.3 - 14.6 m). The results show that selective multiple-tree-handling increases productivity by 20 - 46% compared to single-tree handling. If the trees are cut in boom-corridors (10 * 1 or 2 m strips between strip roads), productivity increases up to 41%, compared to selective multiple-tree-handling. Moreover, if the trees are felled using area-based felling systems, productivity increases by 33 - 199%, compared to selective multiple-tree-handling. For any given harvesting intensity, productivity increased the most in the densest stands with small trees. The results were used to derive time consumption functions. Comparisons with time study results suggest that our simulation model successfully mimicked productivity in real-life forest operations, hence the model and derived functions should be useful for cost calculations and evaluating forest management scenarios in diverse stands
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| 5. |
- Thierfelder, Tomas, et al.
(författare)
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Evaluating the effect of DEM resolution on performance of cartographic depth-to-water maps, for planning logging operations
- 2022
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Ingår i: International Journal of Applied Earth Observation and Geoinformation. - : Elsevier BV. - 0303-2434 .- 1569-8432. ; 108
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Tidskriftsartikel (refereegranskat)abstract
- Reliable and accurate soil moisture maps are needed to minimise the risk of soil disturbance during logging operations. Depth-to-water (DTW) maps extracted from digital elevation models have shown potential for identifying water flow paths and associated wet and moist areas, based on surface topography. We have examined whether DEMs from airborne LiDAR data with varying point density can improve performance of DTW maps in planning logging operations. Soil moisture content was estimated on eight sites after logging operations and compared to DTW maps created from DEMs with resolutions of 2 m, 1 m, and 0.5 m. Different threshold values for wet soil (1 m and 1.5 m depth to water) were also tested. The map performances, measured by accuracy (ACC) and Matthews Correlation Coefficient (MCC), changed slightly (79%, 81% and 82% and 0.33, 0.26 and 0.30 respectively) when DEM resolutions varied from 2 m to 1 m, and 0.5 m. The corresponding values when the DTW threshold value for wet/dry soil changed from 1 m to 1.5 m were 70%, 72%, 71% and 0.38, 0.41 and 0.39. LiDAR-based DEM resolutions of 1–2 m were found to be sufficient for extraction of DTW maps during planning of logging operations, when knowledge about soil hydrological features, associated wet and moist areas, and their connectivity is beneficial.
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| 6. |
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| 7. |
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| 8. |
- Athanassiadis, Dimitris, et al.
(författare)
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HARVESTING POTENTIAL AND PROCUREMENT COSTS OF LOGGING RESIDUES IN SWEDEN
- 2009
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The aim of this study was (i) to provide an estimation of the potential amount of logging residues (branches, tops and stumps with attached root system) that will be produced in Sweden (thinning and regeneration fellings) during the next decade (2010-2019) and (ii) calculate the costs for harvesting the residue, comminute it and bring it to the end user. Depending on the level of ecological, technical and economical restrictions the potential amount of slash (branches, tops and stumps) in regeneration fellings varied from 3.2 to 7.4 Mt OD annually while the potential amount (Mt OD) of stumps varied from 4.2 to 11.7 annually. The corresponding annual figures in thinning for slash and stumps were 1.7 to 3.9 and 1.8 to 5.7 Mt OD annually, respectively. 80% of the potential amount of slash and stumps at level 3 of ecological, technical and economical restrictions in regeneration fellings would be available for 85 EUR/ODT and 110 EUR/ODT, respectively
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| 9. |
- Athanassiadis, Dimitris, et al.
(författare)
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Is there enough primary forest fuel available to feed into the existing and planned CHP facilities? The case of Northern Sweden
- 2010
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Ingår i: Publications / FINBIO. - 1239-4874. ; , s. 77-83
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Konferensbidrag (refereegranskat)abstract
- A combined GIS and optimization method was used to calculate logging residue (slash and stumps) flows and expected costs at the heating or combined heat and power plants (CHP) in Northern Sweden for two logging residue supply chains. Regional primary forest energy availability was estimated considering ecological, technical and economical restrictions. Two supply chains were considered: One supply chain was based on truck transport of the fuel to the CHP plants and the other one was based on collecting the fuel to terminals adjacent to railway lines and transporting it by train to plants that are located in Central Sweden. The costs for each supply chain were calculated based on current costs for harvesting, forwarding, chipping/crushing, machine allocation to the harvesting site, road transport, compensation to the land owner and administration. The lowest cost pathway to the plants was selected. The effects of the establishment of the CHP plants on regional development are discussed
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| 10. |
- Athanassiadis, Dimitris, et al.
(författare)
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Marginalkostnader för skörd av grot och stubbar från föryngringsavverkningar i Sverige
- 2009
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Kostnaden för att ta ut grot och stubbar från föryngringsavverkningar i Sverige har uppskattats och redovisas i form av marginalkostnadskurvor. Beräkningarna baseras på den mängd grot och stubbar som faller ut till följd av föryngringsavverkningar som utförs i referensscenariot i SKA-VB 08 för perioden 2010 - 2019. De potentialer som använts är efter avdrag för ekologiska, tekniska och ekonomiska restriktioner, dvs. nivå 3 i SKA-VB 08. Kostnaderna för uttag av grot och stubbar har beräknats för de maskinsystem som är vanligast förekommande i Sverige och Finland idag. Ersättning till markägare, administrationsomkostnader och kostnader för skörd, sönderdelning, maskinflyttningar och transport av grot och stubbar är de kostnadsposter som ingår i beräkningarna. Grot kan tas ut till en lägre kostnad än stubbar vilket leder till att marginalkostnadskurvan för grot startar på en lägre nivå än marginalkostnadskurvan för stubbar; 600 kr/ton TS för grot respektive 800 kr/ton TS för stubbar. Om kostnaden får öka från 770 till 920 kr/ton TS kan tillvaratagandet av grot öka från dagens ca 2 till 2,9 Mton TS, dvs. 90 % av den tillgängliga potentialen som är 3,2 Mton TS. Först vid en kostnad på 850 kr/ton TS trädbränsle uppgår andelen stubbar till 10 % av sortimentsfördelningen. Vid en kostnad på 1 100 kr/ton TS är sortimentsfördelningen så gott som lika för grot och stubbar. Om 2,5 Mton TS (60 %) av tillgänglig potential stubbar i nuläget ska bli aktuella för skörd blir uttagskostnaden upp till 1 000 kr/ton TS. Omräkningstalet 1 ton TS = 4,9 MWh har använts vid omvandling mellan massa och energi. Detta värde anger mängden energi som kan avges som värme vid förbränning av skogsbränsle med en fukthalt på 40 % när vattnets ångbildningsenergi inte utnyttjas. Om prestationen för de maskiner som ingår i stubbsystemet ökar med 15 % så kan man få ut samma mängd vid 920 kr/ton TS. Kostnadsfördelningen visar att transportkostnaderna är den viktigaste kostnadsposten, speciellt när det gäller små avverkningstrakter, belägna långt från tätort
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| 11. |
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| 12. |
- Athanassiadis, Dimitris, et al.
(författare)
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Procurement costs of slash and stumps in Sweden – a comparison between South and North Sweden
- 2010
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Marginal cost curves were used to appreciate the amount of slash and stumps that could be harvested at certain costs in Sweden as a whole as well as in two regions (Upper Norrland and South Sweden). The expected region specific variations were quantified and region specific estimates on harvestable potentials of stumps and slash were made. The results in this work were based on data collected in the Swedish Forest Inventory (SFI) from 2002 to 2006
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| 13. |
- Athanassiadis, Dimitris, et al.
(författare)
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Regional GIS-based evaluation of the potential and supply costs of forest biomass in Sweden
- 2017
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Ingår i: Frontiers of Agricultural Science and Engineering. - 2095-7505 .- 2095-977X. ; 4, s. 493-501
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Tidskriftsartikel (refereegranskat)abstract
- The potential for harvestable forest fuel (logging residues and stumps from regeneration fellings and small diameter trees from early thinnings) in Sweden, divided in five regions, is provided. Marginal cost curves for logging residues and stumps are calculated through a GIS-based method based on forest inventory plots and locations of selected terminals, and heat and combined heat and power facilities. Four supply chains for logging residues and two for stumpwood were compared. Fixed and variable costs of harvesting equipment and transport vehicles were used for determining the costs of each of the supply systems under consideration. A list with the GPS coordinates of all facilities and terminals was made based on their geographical location. The distance from the center of each forest inventory plot to the nearest receiving point within the region, either facility or terminal, was estimated. There were large differences in the estimated potential of harvestable forest fuel between the regions. The overall annual potential for each of the five regions ranged from 0.97 to 2.73 million oven dry tonnes and the total potential amounted to 9.39 Mt (oven dry). One of the northernmost regions (R1) had the steepest slope in its marginal cost curve. For the other regions, the slope of their cost curves was less dramatic. Information on the economic availability of logging residues and stumps in each region is important for forest fuel suppliers and receiving facilities.
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| 14. |
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| 15. |
- Berg, Simon, et al.
(författare)
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Effect of stump size and timing of stump harvesting on ground disturbance and root breakage diameter
- 2015
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Ingår i: Silva Fennica. - : Finnish Society of Forest Science. - 0037-5330 .- 2242-4075. ; 49
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Tidskriftsartikel (refereegranskat)abstract
- Stump wood is a possible alternative to fossil fuel. Its harvesting, however, disturbs the ground and this has not yet been quantified at stump level. Such disturbance is likely to be dependent on stump size, type of soil and timing of stump harvesting. Therefore, we measured ground disturbance and root breakage diameter at two Norway spruce sites with sandy glacial till soil. The sites were harvested with a fork type head, 6 and 18 months after clear cutting. Measurements were made within 2 weeks of harvest. No difference was found between the two sites. The mean area of disturbed ground was 6.06 (std 3.14) m(2) per stump and increased exponentially with stump size. A regression function modelling the relationship was constructed. Unexpectedly, many fine roots where extracted in the harvest. The arithmetic and basal area weighted mean root breakage diameter was 4.6 (std 2.2) and 29.5 (std 17.9) mm, respectively. There seems to be a limited increase in root breakage diameter with increased stump size. The small root breakage diameter is associated with reduced fuel quality and greater nutrient removal. It appears that much of the ground disturbance is associated with the creation of ruts rather than stump harvest per se. Stump harvesting disturbs a larger percentage of the area of a harvested site than mounding. Postponing stump harvest by one year did not decrease the ground disturbance or increase the root breakage diameter. To achieve less disturbance and larger root breakage diameter, probably new stump harvesting technology is required.
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| 16. |
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| 17. |
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| 18. |
- Berg, Simon, et al.
(författare)
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Simulating conventional and integrated stump- and round-wood harvesting systems: a comparison of productivity and costs
- 2014
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Ingår i: International Journal of Forest Engineering. - : Informa UK Limited. - 1494-2119 .- 1913-2220. ; 25, s. 138-155
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Tidskriftsartikel (refereegranskat)abstract
- Tree stumps could make a signi reliance on fossil fuels. However, ground disturbance due to stump harvesting can be an unintended negative environmental consequence. Harvesting only the central part of the stump can reduce ground disturbance, but this is not pro harvesting of stump-center and round-wood in a single operation. We compare an integrated system for such simultaneous harvesting of stems and stump-centers with a conventional system harvesting stem and stump separately. The conventional system used a harvester, a forwarder, a stump harvester and a stump forwarder, while the integrated system used a feller-puller that fells the trees with the stump center attached, an in-stand processor, and a forwarder. The work of the machines was simulated using discrete-event simulation and the costs of the two machine systems were compared. The integrated system produced only 12 volume produced by the conventional system. The integrated system produced stump-wood at a lower cost than the conventional system for larger trees (>420 mm breast-height diameter). For smaller trees, it was not possible to determine which was the more economical system. Further empirical data are required to resolve the issue, for instance concerning the time required to cut or break the roots around a tree.ficant contribution as a renewable energy source in the transition away fromfitable with the machinery and systems currently used. One possible solution is to integrate the–33% of the stumpwood
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| 19. |
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| 20. |
- Berg, Simon, et al.
(författare)
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Torque required to twist and cut loose Scots pine stumps
- 2012
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Ingår i: Scandinavian Journal of Forest Research. - : Informa UK Limited. - 0282-7581 .- 1651-1891. ; 27, s. 724-733
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Tidskriftsartikel (refereegranskat)abstract
- Stump wood is a possible source of renewable energy, but before its potential as a fuel can be utilised to a high degree, new harvesting techniques should be developed to reduce the environmental impact (notably ground disturbance) of harvesting stumps. The forces required to lift and drag stumps out of the soil are known. In this study, two unknown and important parameters were addressed: the torque required to uproot stumps by twisting them and the torque required to cut lateral roots around stumps. A new, improved stump-twisting rig was designed and used in trials with 28 Scots pine (Pinus sylvestris) trees (breast-height diameter over bark, 153-427 mm). The measured torque requirements ranged from 10 to 50 kNm. Twisting stumps required more torque than cutting lateral roots around stumps and the required torque increased with increases in stump size. The results indicate that a wrist on a big feller-buncher, but not a conventional rotator used on forest machines, should be able to generate sufficient torque to cut the roots around stumps such as those used in this study.
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| 21. |
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| 22. |
- Bergström, Dan, et al.
(författare)
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Comparison of Boom-Corridor Thinning and Thinning From Below Harvesting Methods in Young Dense Scots Pine Stands
- 2010
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Ingår i: Silva Fennica. - : Finnish Society of Forest Science. - 0037-5330 .- 2242-4075. ; 44, s. 669-679
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Tidskriftsartikel (refereegranskat)abstract
- At present, only a small proportion of the potential extractable bioenergy from young dense forests in Sweden is utilized. The conventional mechanized first thinning systems used in such stands suffer from low productivity, so the operation is only profitable in stands with bigger trees and high standing volumes. Conventional harvesters are used for this operation equipped with accumulating felling heads designed for handling several trees during each crane cycle. In thinning from below the felling and bunching work requires many time-consuming nonlinear crane movements to avoid felling or damaging of future crop trees. However, higher productivity can be achieved when trees between strip roads are harvested in about 1 m-wide corridors with a length corresponding to the reach of the crane. We refer to this operation as boom-corridor thinning. The objective of this study was to compare felling and bunching productivity in young dense stands when employing thinning from below or boom-corridor thinning. Experiments were performed using a randomized block design involving between 4400 and 18600 treesxha(-1) with a corresponding average tree size of 7.2 and 3.2 cm dbh, respectively. Based on the average tree being removed at a dbh of 5.7 cm, the productivity (ODtxPW-hour(-1)) was significant (almost 16%) higher for the boom-corridor thinning than for thinning from below treatment. At the same time, the time taken for the work element "Crane in-between" (the period between the loaded crane starting to move towards a tree and the felling head rapidly slowing down for positioning) was significantly reduced, by almost 17%. The positive results were achieved even though the operator was new to the method. To achieve a significantly higher efficiency during the felling and bunching operation, development of new harvesting equipment and operating techniques seems crucial.
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| 23. |
- Bergström, Dan, et al.
(författare)
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Continuous felling of small diameter trees in boom-corridors with a prototype felling head
- 2012
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Ingår i: Scandinavian Journal of Forest Research. - : Informa UK Limited. - 0282-7581 .- 1651-1891. ; 27, s. 474-480
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Tidskriftsartikel (refereegranskat)abstract
- Simulations of the continuous felling of trees in boom-corridors have suggested that it may be possible to increase harvester productivity by a factor of 2.4 when thinning young dense stands. A prototype boom-tip mounted felling head for harvesting in this fashion was therefore built and tested in the field. Using the new head, stands with a density of 10,000 trees ha(-1) and a mean diameter at breast height (dbh) of 7 cm were felled at a speed of 0.4 m s(-1), with an efficiency of 3.5 s tree(-1). The felling speed was limited by the speed of movement of the harvester crane's boom. However, additional tests suggested that the new head could be operated at felling speeds of up to 1.3 m s(-1) when cutting trees with dbh values of up to 8 cm. The simulation that prompted this study focused on multiple felling with the crane in continuous motion at speeds of 1 m s(-1); the results obtained in this work suggest that the new felling head is capable of sustaining these speeds and so further technical development of the design (e.g. to incorporate accumulating functionality) is warranted.
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| 24. |
- Bergström, Dan, et al.
(författare)
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Development of efficient harvesting techniques for young bioenergy-thinnings
- 2011
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Ingår i: Publications / FINBIO. - 1239-4874. ; , s. 172-172
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Konferensbidrag (refereegranskat)abstract
- There has been increasing interest in new harvesting methods, techniques and systems for cost-efficient thinning of forest fuels from young dense stands. Current research has been focusing on applying boom-corridor thinning, meaning that the trees between strip-roads are felled in linear crane movements in narrow e.g. 1-1.5 m wide corridors with lengths corresponding to the cranes reach. Results from simulations, field studies and tests of prototype equipment for geometric boom-corridor thinning between strip-roads show potential to double the productivity, compared to conventional harvesting operations. Currently, efforts are being made to realize the operational possibilities of such technology. As described here, the first steps have been to specify the necessary requirements and evaluate prototypes virtually. The goal is to demonstrate a technical concept for continuous felling and boom-corridor accumulation of trees before bunching at strip-road sides
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| 25. |
- Bergström, Dan, et al.
(författare)
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Effects of Boom-Corridor and Selective Thinnings on Harvester Productivity in Dense Small Diameter Pyrenean Oak (Quercus pyrenaica Willd.) Coppices in Spain
- 2024
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Ingår i: Croatian Journal Of Forest Engineering. - 1845-5719. ; 45
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Tidskriftsartikel (refereegranskat)abstract
- Due to socioeconomic transformations in the 20th century, Quercus pyrenaica Willd. coppices in Spain, as well as other European coppices, have experimented an abandonment and lack of intervention leading to stagnant high density stands with fragile health due to competition. Thinnings are often required to ensure their stability and health, producing forest products such as firewood or biomass, which are key energy sources in a carbon-neutral economy. However, thinnings are seldom performed because they lack economic sustainability due to a low productivity, high costs and low biomass prices. In this study, two thin-ning methods, selective thinning (ST) and boom-corridor thinning (BCT), were tested car-rying out a time study in a high-density small-diameter Q. pyrenaica stand in the Leon province (Castilla y Leon, Spain) with a forest harvester base machine, on which an accumulating felling head Bracke C16c was mounted. The residual stands were significantly different regarding the final density (greater in BCT) and the final average DBH (bigger in ST), while thinning intensity (odt center dot ha-1) was the same. In most work elements, time per tree was not significantly different. BCT showed a significant 48.6% increase in harvester productivity when compared to ST, with averaging 4.43 and 2.99 odt center dot pmh-1, respectively, due mainly to the average weight per extracted tree, 42% greater in BCT. When considering the common range of unit tree weight, the productivity was 16-23% greater for BCT, far less than observed in the trials. These results show the potential of BCT over ST in the studied conditions, although there is room for improvement. Further studies could include the future evolution of the treated stands and perform a cost analysis.
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| 26. |
- Bergström, Dan, et al.
(författare)
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Effects of boom-corridor thinning on harvester productivity and residual stand structure
- 2022
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Ingår i: International Journal of Forest Engineering. - : Informa UK Limited. - 1494-2119 .- 1913-2220. ; 33, s. 226-242
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Tidskriftsartikel (refereegranskat)abstract
- Biomass derived from small-diameter, dense, thinning stands is largely underutilized within the European Union, mainly because of in-effective harvesting methods and cutting technology, leading to high supply costs. Therefore, the efficacy of boom-corridor thinning (BCT) and selective thinning (ST) on harvester felling and bunching productivity was compared for the first thinning of whole tree biomass in small-diameter, dense stands. BCT working method is when trees are cut with linear movements of the harvester's boom reach, along narrow corridors, instead of cutting each tree selectively (ST). Trials were performed in six forest stands, one in Sweden, two in Finland, and three in Slovenia, using the same harvester and operator. A time-and-motion study was carried out in 64 pre-marked study units (32 replications per method), across a variety of stand conditions. The biomass removal for both treatments averaged 40.2 dry t ha -1 and BCT productivity averaged 5.4 dry t PMh -1. For BCT, harvester work time consumption (sec tree -1) and productivity (dry t PMh -1) were on average 27% lower and 16% higher, respectively, compared with ST. The effectiveness of the accumulating felling head technology used could potentially be increased by implementing a feed-roller system when handling excessive tree lengths. Developing dedicated harvesting technology for BCT could further boost productivity, facilitating cost-effective and sustainable utilization of low-value small-diameter tree biomass and replacing fossil resources.
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| 27. |
- Bergström, Dan, et al.
(författare)
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Environmental Impacts of Boom-Corridor and Selectively Thinned Small-Diameter-Tree Forests
- 2022
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Ingår i: Sustainability. - : MDPI AG. - 2071-1050. ; 14
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Tidskriftsartikel (refereegranskat)abstract
- European forest stands of small-diameter trees can provide industries with biomass as an alternative to fossil use. Small-tree harvesting is costly using conventional methods but using accumulating felling heads (AFH) in combination with a novel boom-corridor thinning (BCT) technique can increase harvester productivity and supply cost efficiency. This method has great potential to reduce costs, but its environmental impact compared with selective thinning (ST) needs to be determined. The objectives of this study were therefore to quantify and compare tree and soil damage as well as air, water and soil emissions for both BCT and ST in various European small-diameter-tree forests. Trials were performed in 84 study units (42 replications per thinning technique) across four countries. Damaged trees (with a diameter at breast height >= 7 cm) were measured after thinning and after forwarding. Harvesting emissions were calculated from a life cycle assessment. The percentage of remaining trees that had been damaged by the harvesting processes was 13% and 19% for BCT and ST, respectively, and the difference was significant. BCT exhibited the lowest emissions in all environmental impact categories considered, in all countries. Greenhouse gas emissions were on average 17% lower for BCT. BCT in small-diameter-tree stands therefore reduces the environmental impact of thinning operations compared with conventional methods, and results in less damage to the remaining trees.
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| 28. |
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| 29. |
- Bohlin, Jonas, et al.
(författare)
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Remote measuring of the depth of wheel ruts in forest terrain using a drone
- 2021
-
Ingår i: International Journal of Forest Engineering. - : Informa UK Limited. - 1494-2119 .- 1913-2220. ; 32, s. 224-234
-
Tidskriftsartikel (refereegranskat)abstract
- Even at a well-managed harvesting site, vehicle trafficking occurs on at least 12% of the area and might cause ruts and compaction. The use of drones for inventory and mapping in forestry is still a new method. The purpose of this study was to develop a method for measuring the size and depth of wheel ruts caused by forest machines in harvested areas, using drones and Structure from Motion photogrammetry. In order to investigate the accuracy of drone photogrammetry, measurements from flight altitudes of 60 m and 120 m above ground level were compared with manual measurements. The same methods were used at a control site on farm land, taking into account the rut depth and the location of the sample surface (close to trees or in a fully open area). No statistically significant differences were found between manual measurements and remote measurements from 60 m or 120 m altitude at the harvesting site (R-2 0.77-0.83). At the control site, an underestimation of 2.2 cm of the rut depth was found for remote measurements made from 120 m altitude. The data derived from drone images were able to reproduce the 3D model of surface features, such as bulges and ruts; these measurements were considered to be equivalent to manual measurements. For practical applications, a post-harvest survey using drones could contribute to verifying compliance with international forest certification standards or by private contractors to evaluate rut formation on their harvest sites.
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| 30. |
- De La Fuente, Teresa, et al.
(författare)
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Cradle-to-gate life cycle assessment of forest supply chains: Comparison of Canadian and Swedish case studies
- 2017
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Ingår i: Journal of Cleaner Production. - : Elsevier BV. - 0959-6526 .- 1879-1786. ; 143, s. 866-881
-
Tidskriftsartikel (refereegranskat)abstract
- This study took a Life Cycle Assessment (LCA) perspective to model a total of twenty forest supply chains, from seedling production to forest biomass delivery to industry. Four scenarios were analyzed, two in Sweden and two in Canada. Resource and energy consumption, and emissions to air, water and soil of conventional and biomass dedicated supply chains were evaluated and compared.The Swedish supply chains showed a better environmental profile, on average, per oven dry tonne (0Dt) than the Canadian ones in the regions studied. In terms of climate change potential the Swedish biomass dedicated supply chains generated 48.8 kg CO2-eq, 13%, 30% and 38% lower than Swedish conventional, Canadian biomass dedicated and Canadian conventional supply chains, respectively. Sawlogs from final felling in the Swedish biomass dedicated supply chains generated 34.2 kg CO2-eq, the lowest emissions within the roundwood assortments. Concerning the forest fuel assortments in form of wood chips, pulpwood from final felling in the Swedish conventional supply chains, and stump core and long tops from final felling in the Swedish biomass dedicated supply chains generated the lowest emissions: 48.9 kg CO2-eq, 52.3 Kg CO2-eq and 57.8 kg CO2-eq respectively. Transport from forest to industry, harvesting, extraction, chipping, and crushing were identified as hotspots in the forest supply chains. Forwarding versus skidding, chipping and transportation were the processes that differed the most between countries.In both countries, when the supply chains were biomass dedicated the environmental impacts per ODt were lower than in the conventional supply chains. Therefore, integrating forest fuel supply with industrial wood harvesting has the potential to reduce emissions. (C) 2016 Elsevier Ltd. All rights reserved.
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| 31. |
- De La Fuente, Teresa, et al.
(författare)
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Fuel consumption and GHG emissions of forest biomass supply chains in Northern Sweden: a comparison analysis between integrated and conventional supply chains
- 2017
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Ingår i: Scandinavian Journal of Forest Research. - : Informa UK Limited. - 0282-7581 .- 1651-1891. ; 32, s. 568-581
-
Tidskriftsartikel (refereegranskat)abstract
- Forest biomass can be used as source of renewable energy, contributing to mitigate climate change. Currently, forest biomass is one of the most important energy sources in Sweden, accounting for around 20% of the total supply. New demands of forest biomass may be expected due to the European Union energy targets, the previous high oil prices, the energy supply security, and the bioenergy market. However, the supply depends on the intensity of conventional final felling operations. Thus, it is crucial to determine the energy demands of conventional and new forest assortment supply chains and promote those with the highest energy efficiency and least greenhouse gas (GHG) emissions. An attributional life cycle assessment approach was used to evaluate the fuel consumption and GHG emissions associated with the combustion of fossil fuels used in forest operations, transportation and comminution of forest biomass procured via two kinds of supply chains in Northern Sweden: conventional and integrated. The results indicate that most fuel was consumed in transportation processes. The integrated supply chains (in which the harvesting of industrial roundwood is integrated with extraction of forest fuels) are more energy efficient than conventional supply chains, and have the potential to reduce GHG emissions by approximately 13%.Abbreviation: BWT: bundled whole small trees; CTL: Cut-to-length; ET: energy thinning; FF: final felling; FT: first thinning; FU: functional unit; GHG: greenhouse gas; GWP: global warming potential; LCA: life cycle assessment; LR: logging residues; LT: long tops; ODt: oven dry tonne; ORN: ornskoldsvik (industrial location); PCT: pre-commercial thinning; PL: pulpwood; PM(15)h: Productive machine hours including delays shorter than 15min; RS: Rough-delimbed tree sections; SC: stump core; SL: sawlogs; SP: stumps; ST: second thinning; STO: Storuman (industrial location); u.b: under bark; UME: Umea (industrial location)
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| 32. |
- Di Fulvio, Fulvio, et al.
(författare)
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Comparison of energy-wood and pulpwood thinning systems in young birch stands
- 2011
-
Ingår i: Scandinavian Journal of Forest Research. - : Informa UK Limited. - 0282-7581 .- 1651-1891. ; 26, s. 339-349
-
Tidskriftsartikel (refereegranskat)abstract
- In early thinnings, a profitable alternative to pulpwood could be to harvest whole trees as energy-wood. In theoretical analyses, we compared the extractible volumes of energy-wood and pulpwood, and their respective gross values in differently aged stands of early birch thinnings at varying intensities of removal. In a parallel field experiment, we compared the productivity at harvest of either pulpwood or energy-wood, and the profitability when the costs of harvesting and forwarding were included. The theoretical analyses showed that the proportion of the total tree biomass removed as pulpwood increased with increasing thinning intensity and stem size. The biomass volume was 1.5-1.7 times larger than the pulpwood volume for a 13.9 diameter at breast height stand and 2.0-3.5 times larger for a 10.4 diameter at breast height stand. In the field experiment, the harvested volume per hectare of energy-wood was almost twice as high as the harvest of pulpwood. The harvesting productivity (trees Productive harvesting Work Time-hour-1) was 205 in the energy-wood and 120 in the pulpwood treatment. The pulpwood treatment generated a net loss, whereas the energy-wood treatment generated a net income, the average difference being 595 ha-1. We conclude that in birch-dominated early thinning stands, at current market prices, harvesting energy-wood is more profitable than harvesting pulpwood.
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| 33. |
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| 34. |
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| 35. |
- Di Fulvio, Fulvio, et al.
(författare)
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Productivity and Profitability of Forest Machines in the Harvesting of Normal and Overgrown Willow Plantations
- 2012
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Ingår i: Croatian Journal Of Forest Engineering. - 1845-5719. ; 33, s. 25-37
-
Tidskriftsartikel (refereegranskat)abstract
- Forage harvesters used in Short Rotation Willow Coppice (SRWC) plantations in Sweden suffer from an inability to efficiently harvest stems thicker than 6-7 cm at stump height. An alternative, when harvesting in such plantations, might be to use forest machines fitted with accumulating felling heads. This study aimed to measure the time consumption and to compare the costs of two forest machine systems in a normal (N) and an overgrown (0) SRWC, where the respective biomass densities were 36 and 56 Oven-Dry tonnes (OD t) per ha. The first machine system included a harvester and a forwarder and the second consisted of a harwarder (one-machine system). When harvesting and forwarding the biomass for 250 in, the productivity of the two and one-machine system was on average 2.3 (sd = 0.6) and 0.9 (sd = 0.2) OD t/Productive Work hour, respectively. Biomass density or stem sizes had a marginal effect on the time consumption per hectare for the two-machine system, but were significant for the one-machine system. The productivity for the two-machine and one-machine system in the O area, compared to the N area, was 40% and 36% higher, respectively. The net income was positive when using the harvester-forwarder system but it was negative for the harwarder. Increases in biomass density or stem sizes increased the profitability of the machine systems studied. Thus, if dealing with more overgrown plantations than those studied, forest machines, and especially a harvester-forwarder system, may offer an efficient and economical alternative to conventional forage harvesters.
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| 36. |
- Di Fulvio, Fulvio, et al.
(författare)
-
Skörd av skogsbränsle och/eller massaved i förstagallringar, vägkanter och på igenväxt åkermark
- 2011
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Vid gallring används samma typ av basmaskiner för sortimenten skogsbränsle och massaved. Ett beslut om val av sortiment grundar sig därför främst på de mängder massaved respektive skogsbränsle som kan genereras i en avverkning och den aktuella prisrelationen mellan skogsbränsle och massaved. Under åren 2009 och 2010 utfördes driftsuppföljningar på avverkningsobjekt i Västerbotten vid skörd av skogsbränsle och massaved i unga skogar. Syftet med datainsamlingen var att beräkna de olika maskinernas och systemens produktivitet, kostnader och netto vid skörd och transport till vägkant Datamaterialet delades upp i två kategorier av avverkningar: 1) ”gallring” och 2) ”vägröjning & kalavverkning”. Kalavverkning utfördes på. igenväxt åkermark, åkerkanter och vägkanter. Totalt bestod datamaterialet av 43 avverkningsobjekt, varav 34 var ”gallring” och 9 var ”vägröjning & kalavverkning”. Avverkningsobjekten grupperades i fyra grupper utifrån typ av maskinsystem (skördare och skotare eller drivare) och storlek på maskiner (medelstora eller små). Som ett komplement till driftsuppföljningen utfördes tidsstudier på sammanlagt fyra olika maskinsystem vid skörd av skogsbränsle i samma region som ovan under barmarkssäsongen 2010. Tre maskinsystem bestod av en skördare och en skotare och ett maskinsystem bestod av en liten drivare. Totalt 16 studieytor inventerades både före och efter skörd. Bestånden hade före skörd i medeltal 3653 stammar/ha och i medeltal skördades det 2025 stammar/ha vilket motsvarade ca 25 ton torrsubstans (TS) (ca 50 m3f biomassa) per ha. Från de 43 avverkningsobjekten i driftsuppföljningen skördades totalt 16179 m3f biomassa (m3f bio) skogsbränsle och 1906 m3fub massaved från en total skördad areal av 295 ha. Medelobjektet var på 6,9 ha. I de 34 gallringsobjekten skördades i medeltal 49 m3f bio/ha skogsbränsle med en medelstamvolym av 25 dm3sk. I 9 av gallringsobjekten skördades både skogsbränsle och massaved (integrerad gallring). Medelstamvolymen var 36 dm3sk och det skördades i medeltal 37 m3f bio skogsbränsle och 11 m3fub massaved per ha. Den totala avverkningskostnaden blev i medeltal 15965 kr/ha för skördare och skotaresystemet. Vid enbart gallring av skogsbränsle och vid integrerad gallring blev intäkten 11301 kr/ha respektive 11509 kr/ha. I vägröjnings- och kalavverkningsobjekten var intäkten i medeltal 29687 kr/ha. I gallringsobjekten blev nettointäkten i medeltal -5842 kr/ha (min -16543, max 2130 kr/ha) och i kalavverkningsobjekten i medeltal -3397 kr/ha (min -8001 kr/ha, max 2610 kr/ha). I medeltal blev nettointäkten i gallring av skogsbränsle och integrerad gallring -6781 kr/ha respektive -3341 kr/ha. Tidsstudien visade att ett avverkningssystem bestående av en medelstor skördare och en medelstor skotare ger en lönsam skörd av skogsbränsle om medelstamvolymen överstiger ca 30-35 dm3sk (dbh > ca 8-9 cm). Detta resultat är i enlighet med tidigare studier utförda både i Sverige och i Finland. Det finns ett fortsatt behov av utveckling av teknik och arbetsmetoder för skörd av klena stammar, där system för integrerad skörd av både massaved och skogsbränslen i bestånd där den skördade medelstammen överstiger ca 30 dm3sk sannolikt kan ge ökad kostnadseffektivitet i jämförelse med att bara skörda ett av sortimenten; -- In early thinnings where either pulpwood or energy wood is harvested, the same logging machines are generally used for both products. The choice between pulpwood or energy wood is therefore mostly dependent on the harvestable volumes of the two assortments and the price difference. During the years 2009-2010 follow up studies on machine performance in early thinnings were performed in the coastal region of Västerbotten. The purpose was to study the time consumption, production and costs for harvesting of energy wood and pulpwood, either in separate operations or through integrated harvest of both assortments. In total 43 different harvesting objects were included in the study of which 34 were early thinning stands and 9 were harvesting of e.g. road sides and overgrown arable land. During the year 2010 the follow up studies were complemented with time studies of three of the machine systems; three harvester and forwarder systems and a small harwarder system were studied. In the follow up study, a total of 16179 m3solid energy wood and 1906 m3solid on bark pulpwood were harvested from an area of 295 ha. In the thinning stands the average harvested stem size was 25 dm3solid and on average 49 m3solid biomass per ha of energy wood. In 9 of these stands an integrated harvest of pulpwood and energy wood was performed. The average stem size of the removed stems was 36 dm3solid, and in average 37 m3solid energy wood per ha and 11 m3solid pulpwood per ha were harvested. The harvesting costs for the harvester and forwarder system were on average 15965 SEK/ha. The time study shows that a harvesting system with a medium sized harvester and forwarder in energy wood thinning is profitable when the harvested tree size reaches ca 30-35 dm3solid (diameter at breast height ca 8-9 cm). These results are in line with previous finding from both Sweden and Finland. Further development of harvesting systems for integrated harvesting of energy wood and pulpwood will make the extraction of biomass from early thinning more profitable, in stands were the mean harvested tree size reach at least 30 dm3solid, in comparison to extract only one assortment
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| 37. |
- Edlund, Björn, et al.
(författare)
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Quad Bike Riders’ Attitudes toward and Use of Safety Technologies
- 2019
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Ingår i: Journal of Agricultural Safety and Health. - : American Society of Agricultural and Biological Engineers (ASABE). - 1074-7583 .- 1943-7846. ; 25, s. 169-187
-
Tidskriftsartikel (refereegranskat)abstract
- Worldwide, the number of quad bike-related injuries and fatalities has increased over the last 30 years and, although quad bike safety has become increasingly important over the last decade, greater understanding of the risks associated with these vehicles is required. This study aimed to improve understanding of the interrelationships between risk perception, risk management, and the use of safety technologies in quad bike operation. A total of 70 quad bike riders were interviewed in two sets of interviews: one targeting riders visiting two forestry fairs, and the other targeting riders with quad bikes equipped with ROPS. The interviews showed that the quad bike riders had a tendency for externalization of risk. This result possibly derives from the articulation and allocation of blame; the majority of respondents saw the problem of quad bike safety as a result of faulty rider behavior, thus shifting focus away from the technology as well as from themselves. This also applies to many of the interviewed ROPS owners, as one of their prime motivators in acquiring ROPS was to improve the safety of others rather than their own safety.
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| 38. |
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| 39. |
- Edlund, Björn, et al.
(författare)
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The effect of rollover protection systems and trailers on quad bike stability
- 2020
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Ingår i: International Journal of Forest Engineering. - : Informa UK Limited. - 1494-2119 .- 1913-2220. ; 31, s. 95-105
-
Tidskriftsartikel (refereegranskat)abstract
- Quad bikes are light-weight vehicles which are used for transportation of personnel, equipment, and material in forestry operations such as planning, logging, planting, and fire-fighting. With increased quad bike usage, serious injuries have become an increasing concern. The most common forms of severe incidents occur when a quad bike loses stability, causing injuries as it rolls over the rider trapped beneath. The risk of injuries during a rollover incident can be decreased by equipping the vehicle with rollover protection systems (ROPS), but since ROPS tend to decrease the stability of quad bikes, their use can be a trade-off between the risk of overturning and the outcome of any such incident. In this study, we examine the effects of approach angle, trailer load, ROPS and different hardware configurations on a quad bike’s static stability. We found that approach angle and trailer configurations influenced the vehicle’s stability, although the effect was difficult to quantify in a static environment. Furthermore, the quad bike’s stability was negatively influenced by equipping it with a heavy (44 kg) ROPS. It reduced the static stability by an average of 5.1°, while a light (14.7 kg) prototype ROPS only reduced the vehicle’s static stability by an average of 1.0°. The negative impact a ROPS has on a quad bike’s lateral stability could be effectively counteracted by increasing the quad bike’s track width. Increasing track width by less than 2% (20 mm) compensated for any negative impact that the light prototype ROPS had on the quad bike’s lateral stability.
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| 40. |
- Eriksson, Gunnar, et al.
(författare)
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Production costs and markets for pellet chips: case studies in northern Sweden
- 2012
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Ingår i: International Journal of Forestry Research. - : Hindawi Limited. - 1687-9368 .- 1687-9376. ; 2012
-
Tidskriftsartikel (refereegranskat)abstract
- Increasing use of woody fuels requires that nontraditional types of raw materials are exploited, including logging residues and small-diameter trees. Although medium-scale combustors often use pellets, they could conceivably use dried chips of sufficiently narrow size distribution (henceforth pellet chips). The influence of the following factors on the relative cost-effectiveness of producing pellets and pellet chips was investigated for three plant sites in northern Sweden: (1) harvesting and transporting of forest residues; (2) the potential of existing energy plants to supply drying heat in periods of capacity surplus; (3) the distance to potential end-users. Data from the national forest inventory were used to estimate raw material costs. The resulting production costs were 144–176 $ per oven-dry tonnes (OD t) for pellets (27.4–33.5 $ MWh−1) and 143–173 $ OD t−1 (27.2–33.0 $ MWh−1) for pellet chips, with harvesting, forwarding, chipping, and transporting of logging residues to the sites amounting to 114–122 $ OD t−1 (21.7–23.2 $ MWh−1) for both fuels. Even though the differences in production costs were minor, the production of pellet chips requires significantly less electricity input per OD t of produced fuel. For cost reductions improved methods for wood fuel procurement, compacting and transporting of chips, small-scale low-temperature drying and foliage and bark separation are needed.
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| 41. |
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| 42. |
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| 43. |
- Fernandez Lacruz, Raul, et al.
(författare)
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Distribution, characteristics and potential of biomass-dense thinning forests in Sweden
- 2015
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Ingår i: Silva Fennica. - : Finnish Society of Forest Science. - 0037-5330 .- 2242-4075. ; 49
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Tidskriftsartikel (refereegranskat)abstract
- Understanding the characteristics of unutilized biomass resources, such as small-diameter trees from biomass-dense thinning forests (BDTF) (non-commercially-thinned forests), can provide important information for developing a bio-based economy. The aim of this study was to describe the areal distribution, characteristics (biomass of growing stock, tree height, etc.) and harvesting potential of BDTF in Sweden. A national forest inventory plot dataset was imported into a geographical information system and plots containing BDTF were selected by applying increasingly stringent constraints. Results show that, depending on the constraints applied, BDTF covers 9–44% (2.1–9.8 M ha) of the productive forest land area, and contains 7–34% of the total growing stock (119–564 M OD t), with an average biomass density of 57 OD t ha–1. Of the total BDTF area, 65% is located in northern Sweden and 2% corresponds to set-aside farmlands. Comparisons with a study from 2008 indicate that BDTF area has increased by at least 4% (about 102 000 ha), in line with general trends for Sweden and Europe. Analyses revealed that the technical harvesting potential of delimbed stemwood (over bark, including tops) from BDTF ranges from 3.0 to 6.1 M OD t yr–1 (7.5 to 15.1 M m3 yr–1), while the potential of whole-tree harvesting ranges from 4.3 to 8.7 M OD t yr–1 (10.2 to 20.6 M m3 yr–1) depending on the scenario considered. However, further technological developments of the harvest and supply systems are needed to utilize the full potential of BDTF.
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| 44. |
- Hellström, Thomas, 1956-, et al.
(författare)
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Autonomous forest vehicles : historic, envisioned, and state-of-the-art
- 2009
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Ingår i: International Journal of Forest Engineering. - 1494-2119 .- 1913-2220. ; 20:1, s. 33-38
-
Tidskriftsartikel (refereegranskat)abstract
- The feasibility of using autonomous forest vehicles (which can be regarded as logical developments in the ongoing automation of forest machines), the systems that could be applied in them, their potential advantages and their limitations (in the foreseeable future) are considered here. The aims were to analyse: (1) the factors influencing the degree of automation in logging; (2) the technical principles that can be applied to autonomous forest machines, and (3) the feasibility of developing an autonomous path-tracking forest vehicle. A type of vehicle that is believed to have considerable commercial potential is an autonomous forwarder. The degree of automation is influenced by increased productivity, the machine operator as a bottle-neck, cost reduction, and environmental aspects. Technical principles that can be applied to autonomous forest vehicles are satellite navigation, wheel odometry, laser scanner and radar. A new path-tracking algorithm has been developed to reduce deviations from the desired path by utilizing the driver’s steering commands. The presented system has demonstrated both possibilities and difficulties associated with autonomous forest machines. It is in a field study shown that it is quite possible for them to learn and track a path previously demonstrated by an operator with an accuracy of 0.1m on flat ground and also to detect and avoid unexpected obstacles. Although the forest machine safely avoids obstacles, the study shows that further research in the field of obstacle avoidance is needed to optimize performance and ensure safe operation in a real forest environment.
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| 45. |
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| 46. |
- Häggström, Carola, et al.
(författare)
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Vibration exposure in forwarder work : effects of work element and grapple type
- 2016
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Ingår i: Croatian Journal of Forest Engineering. - : University of Zagreb. - 1845-5719. ; 37:1, s. 107-118
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Tidskriftsartikel (refereegranskat)abstract
- Exposure to whole body vibration (WBV) is a major concern in mechanized forestay work because its adverse effects may become exacerbated by repetitive hand and arm movements, and non neutral body postures. Moreover, shock-type vibrations have recently been suggested as a possible agent behind pains in the neck and shoulders of forest machine operators. Shocks have been identified in forwarders during loading, but the effects of crane work in forwarders have, to the best of our knowledge, not been studied. Thus, the aim of this study was to assess contributions of crane work elements, and potential effects of the use of three grapple and brake-link combinations, to vibration exposure levels in a small forwarder. Repeated measurements of cabin WBV were acquired, and work elements timed, as a single experienced operator forwarded wood piles on a standardized track in northern Sweden, using the same forwarder and work procedures with each grapple and brake-link combination. The studied crane equipment was found to have little or no effect on the daily WBV exposure. Furthermore, exposure to shock-type vibrations while loading appears to be due to driving rather than crane work. However, there were fewer collisions with remaining trees while using the tilt grapple with brake link, suggesting its use provides a more relaxed and comfortable work environment for forwarder operators and financial benefits for the forest owner by reducing damage in the remaining stand.
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| 47. |
- Kons, Kalvis, et al.
(författare)
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Characteristics of Swedish forest biomass terminals for energy
- 2014
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Ingår i: International Journal of Forest Engineering. - : Informa UK Limited. - 1494-2119 .- 1913-2220. ; 25, s. 238-246
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Tidskriftsartikel (refereegranskat)abstract
- Forest biomass terminals provide diverse services to the forest industry: buffer storage, transfers of material between different modes of transport, raw material upgrading, etc. Terminals’ operational costs are highly sensitive to their layout and design. In order to design efficient terminals, it will be essential to understand the current state of forest terminals. To this end, a survey was sent out to companies operating forest terminals for energy in Sweden. The respondents were asked to provide information about their terminals’ areas, volumes of material handled, equipment, inventory methods and age. The terminals were grouped into four size classes according to their surface area. Most terminals covered<5ha; terminals in this class accounted for 65% of the country’s total terminal area. In addition, more than half the country’s total forest biomass output was handled at terminals of<2ha. The extent of paving at terminal size classes varied widely from 28 to 60%. Studied terminals handled 14 different assortments; on average, each individual terminal handled 2.4–4.0 assortments. The most widespread assortment was energy wood which accounted for 63% of the total volume handled. Larger terminals were older, often had better measurement equipment than smaller ones and relied more heavily on third parties to perform inventories. Conversely to big terminals, smaller terminals were more likely to have mobile machinery. Our results provide a detailed overview of the state of Sweden’s forest terminals and will be useful in the design of improved biomass terminals in future.
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| 48. |
- Kronholm, Thomas, et al.
(författare)
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Implementering av skyddsbågar på fyrhjulingar : en utvärdering av användares erfarenheter av ett vältskydd
- 2023
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Intresset för fyrhjulingar har ökat under de senaste åren och fyrhjulingen är idag ett frekvent använt arbets- och nöjesfordon i Sverige. Enbart under år 2021 registrerades 12 000 nya fyrhjulingar i Sverige. Med en mer utbredd användning av fyrhjulingar så har också antalet allvarliga olyckor och dödsfall i samband med fyrhjulingskörning ökat. Trafikverket, försäkringsbolag, skogsföretag, forskare och en del branschorganisationer har under de senaste åren därför initierat flera projekt och insatser i syfte att öka säkerheten och minska antalet omkomna och skadade fyrhjulingsanvändare. En säkerhetshöjande åtgärd som återkommande lyfts fram i forskningen är att utrusta fyrhjulingen med ett vältskydd, en så kallad skyddsbåge, som skyddar föraren vid vältningsolyckor. Vid en vältningsolycka riskerar föraren att hamna i kläm under maskinen, men med ett vältskydd som hindrar maskinen från att rulla runt så minskar denna risk betydligt. I vissa länder, t.ex. Australien, finns idag krav på att fyrhjulingar skall vara utrustade med någon typ av vältskydd. I Sverige har intresset för att utrusta fyrhjulingen med vältskydd hittills varit begränsat. En del studier har pekat på att det både bland förare och tillverkare har funnits ett motstånd mot implementering av vältskydd, bl.a. på grund av en oro för att det skulle vara hindrande för normal användning.Det övergripande syftet med detta projekt har varit att kartlägga och beskriva erfarenheterna från en stor grupp med användare av fyrhjuling med vältskydd och därigenom öka säkerheten och det allmänna medvetandet om nyttan med vältskydd på fyrhjulingar. En målsättning är att detta arbete kan skynda på utvecklingen av säkerheten för fyrhjulingar och på sikt leda till en storskalig implementering av vältskydd i Sverige, i likhet med den utveckling som redan skett i andra länder.För kunna samla in erfarenheter från fyrhjulingsanvändare med vältskydd så importerades vältskydd av märket Quadbar från Australien och distribuerades till ca 50 personer som hade anmält intresse att montera ett vältskydd på sin fyrhjuling och därefter dela med sig av sina synpunkter och erfarenheter. Dessa synpunkter samlades in vid tre olika enkättillfällen. Den första enkäten gjordes inför monteringen av vältskyddet, den andra efter en kortare tids användning och den sista drygt ett år efter att vältskyddet hade monterats. Den första enkäten besvarades av 50 deltagare, den andra av 38, och den sista enkäten besvarades av 37 deltagare.De vanligaste farhågorna inför projektet var att vältskyddet skulle påverka körningen och framkomligheten, eller att det skulle vara hindrande för transporter. Exempelvis att det kan fastna i låg hängande grenar eller liknande och därmed orsaka en olycka. Andra farhågor var att det skulle vara hindrande för användningen av vissa redskap, så som vinsch eller släp. Ur ett säkerhetsperspektiv var deltagarna generellt positivt inställda till vältskyddet.En stor majoritet av deltagarna använde normalt sin fyrhjuling till transporter av material, person och utrustning i skogsbruket, eller till transporter på gården. Färre än hälften använde den normalt till nöjesåkning. De vanligaste terrängtyperna som fyrhjulingen framfördes i var skogsmark, enskild väg, traktorväg och jordbruksmark. En mindre andel av deltagarna framförde i normala fall fyrhjulingen på allmän väg. Det var mycket vanligt att fyrhjulingen kördes tillsammans med ett tillkopplat släp som saknade bromsar. Drygt hälften av deltagarna transporterade även last på fyrhjulingens bakre eller främre lastbåge.Under testperioden var ca 20 % av deltagarna med om en olycka eller incident med sin fyrhjuling. Totalt inrapporterades tio olyckor eller incidenter. Vid de vältningsolyckor som inträffat hade vältskyddet fungerat som det var tänkt och haft en positiv inverkan på utfallet, enligt de beskrivningar som deltagarna har lämnat. Vid några av de mindre allvarliga incidenterna hade förarna av ovana eller oaktsamhet missbedömt den nya höjden på ekipaget eller glömt bort att de Sammanfattning hade vältskyddet bakom ryggen, vilket hade lett till att vältskyddet hade tagit i när de kört under låga passager (t.ex. en klädlina). Inga personskador har inrapporterats i samband med incidenterna.Deltagarna var generellt nöjda med den vältskydd de hade haft, vilket framgår av att en stor andel uttryckte att det var troligt eller mycket troligt att de skulle rekommendera Quadbar till sina bekanta. Resultaten visar också att deltagarnas säkerhetskänsla ökade med vältskyddet monterad på fyrhjulingen. Detta gällde både för deras egen och för andra förares säkerhet. Deras trygghetskänsla ökade över tid.De mest vanliga bekymren som en del deltagare hade upplevt var att det aktuella vältskyddets infästning försämrade möjligheten att koppla till släpp på fyrhjulingen, samt att det försvårade användningen av vinsch. Den medföljande dragkroksförlängaren ansågs i vissa fall ha för dålig hållfasthet. Några deltagare hade därför gjort modifieringar på vältskyddet, dess infästning, eller något tillbehör till denna för att kunna nyttja fyrhjulingen enligt sina egna behov. Att vältskyddet gjorde ekipaget högre försvårade också transport av fyrhjulingen på släp med kåpa. Flera deltagare efterlyste därför en smidigare lösning för att tillfälligt kunna plocka av eller vika ner vältskyddet. Liknande önskemål hade de som ville kunna använda vinsch eller för att komma åt förvaringsutrymmen som annars blockerades av vältskyddet.En av studiens slutsatser är att vältskyddet generellt verkar ha fungerat bra för de flesta av deltagarna, och användningen av vältskydd kan öka både den upplevda och den faktiska säkerheten vid fyrhjulingsanvändning. Deltagarnas positiva inställning till att rekommendera vältskyddet till bekanta kan antas bidra till ett ökat intresse hos fler att införskaffa denna eller liknande vältskydd. Projektet har också synliggjort vad som särskilt behöver utvecklas för att just Quadbar ska bli ännu bättre lämpad för fyrhjulingsanvändare som främst nyttjar den i skogsbruket.
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- Li, Songyu, 1994-
(författare)
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Vision based perception systems for unmanned forestry machines
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- After years of continuous development in the past decades, the field of forest production has achieved a notable degree of mechanization. Nonetheless, the unceasing demand for increased productivity in forestry operations continues to drive the rapid expansion of forestry automation. Critical aspects of forest production, including activities such as harvesting, forwarding, seedling planting, and soil preparation, hold significant potential for improved automation. These advancements promise numerous advantages, such as heightened production efficiency, reduced environmental impact, reduced operational costs, and the creation of a more favourable work environment. Beyond fostering industrial progress, such innovations could also make a positive contribution to the sustainable development of forestry.Forestry operations take place in intricate natural forest environments, rendering the automation of these processes complex and challenging. To realize full automation of forest machines, it is imperative to equip them with environmental awareness and cognitive capabilities. This can be achieved by integrating advanced imaging sensors with sophisticated algorithms, thereby enabling forest machinery to possess a vision system. By utilizing both novel and existing solutions for object detection, positioning, categorization, and status analysis within the machine's surroundings, combined with intelligent decision-making and control mechanisms, forest machinery can attain a higher degree of operational automation.This thesis primarily focuses on the development, deployment, and validation of vision systems on an unmanned forestry machine platform, with a special emphasis on the prototype development of essential features that are still manually executed in contemporary forestry operations. These features include forest terrain obstacle detection, roundwood pose estimation, automated selection of seedling planting locations, and autonomous obstacle avoidance for mounders.In this thesis, vision systems rooted in color and stereo camera sensing are designed and deployed on an unmanned forest machinery platform. These systems encompass the following key functionalities:• A precise positioning system for detecting forest terrain obstacles, such as stones and stumps, using stereo camera data in conjunction with deep learning techniques.• Localization and pose estimation capabilities for ground logs, leveraging stereo cameras and deep learning.• An analysis of the planning area for obstacle detection, along with the extraction of feasible planting zones for establishing seedling planting locations.• The development of an automated obstacle avoidance system for forestry mounders, powered by visual solutions.Through rigorous testing in real-world scenarios spanning logging, loading, planting, and site preparation, this paper demonstrates the feasibility and practicality of enhancing the level of automation in forest machinery operations through the integration of vision systems. It culminates in the creation of tangible and efficient functional prototypes, leading towards a new era of automation in the field of forestry.
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