Doctoral Degrees (Forest and Wood Science)

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Browsing Doctoral Degrees (Forest and Wood Science) by Author "Ackerman, Pierre Alexander"

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    Supply chain management to integrate strategic, tactical and operational planning of wood procurement in the Eastern Cape
    (Stellenbosch : Stellenbosch University, 2015-12) Ackerman, Pierre Alexander; Pulkki, R. E.; Stellenbosch University. Faculty of AgriSciences. Dept. of Forest and Wood Science.
    ENGLISH ABSTRACT: This study quantifies and models potential monetary gains and improved resource utilisation of a typical forest to mill softwood sawlog supply chain in South Africa through incremental improvements of the various stages of the wood procurement process, given road, silvicultural and management costs. The findings are based on the outcomes of four studies: fibre losses during the timber harvesting phase; establishing a primary transport wander ratio, travel speeds and operations efficiencies; predicting secondary transport travel speeds along with a study of current and potential efficiencies in softwood sawlog transport; and finally a supply chain management case study. Fibre loss analysed losses occurring in motor-manual and mechanised felling systems, in tree volume above and below 1 m3 , and merchandising at either roadside landing or centralised merchandising yard. Fibre volume losses were categorised according to stump wood, felling and crosscut saw kerfs, log trimming allowance, wood left in field, and excessive trimming and removal of utilisable wood. Total losses ranged from 6.7% and 9.9% of total utilisable volume with stumps generally felled 7 cm higher than necessary. Based on the volume of wood not recovered, the revenue lost was R393 million in board products and R166 million in roundwood supply from plantations annually. The second study found a wander ratio of 1:1.2. In terms of predicting travel speeds of primary transport, gross power rating (kW), payload size (m3 ), extraction distance (m) and slope (%) variables were included. Skidder payloads were found to be approximately 50% of potential design loads. Truck travel speed predictor variables included Visual Condition Index (VCI), road width, average gradient, percentage of maximum load and truck maximum power. Applying multivariate analysis the predictor variables were reduced to road width and percentage maximum load, and a multiple linear regression equation was produced with an adjusted r2 of 0.52. Analysis found that overloading of trucks was a common occurrence. The Case Study required the current forest road network to be repeatedly refined through road decommissioning and selected upgrades over which the timber resource is subsequently flowed to the processing plant. Based on sequentially improved truck speeds, skidder efficiency and fibre use the Net Present Value (NPV) of the various projects, production costs and available timber resource use were quantified. The supply chain was analysed by investigating the effect downstream efficiency improvements have on financial returns over one rotation. NPV results ranged from approximately R40 million to R300 million. The scenario associated with the highest NPV used the most improved road network, highest possible transport speed, and motor-manual felling, cable skidder extraction, merchandising yard and optimal skidder and transport performance. The lowest NPV yielding scenario is associated with an abridged road network, low secondary transport speed, cable skidder extraction, mechanised felling, roadside merchandising, and normal skidder and transport performance. Examination of the individual factors found that road network; secondary transport speeds and performance had a significant effect. Harvest system had no significant effect. A limitation of this study was that only the forest to mill supply chain was analysed. Extending the supply chain to the mill and onto the final customer the benefits to the entire chain are expected to increase further. This gap in knowledge is a likely follow-up study.
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    Supply chain management to integrate strategic, tactical and operational planning of wood procurement in the Eastern Cape
    (Stellenbosch : Stellenbosch University, 2015-12) Ackerman, Pierre Alexander; Pulkki, E.; Stellenbosch University. Faculty of AgriSciences. Dept. of Forest of Wood Science.
    ENGLISH ABSTRACT: study quantifies and models potential monetary gains and improved resource utilisation of a typical forest to mill softwood sawlog supply chain in South Africa through incremental improvements of the various stages of the wood procurement process, given road, silvicultural and management costs. The findings are based on the outcomes of four studies: fibre losses during the timber harvesting phase; establishing a primary transport wander ratio, travel speeds and operations efficiencies; predicting secondary transport travel speeds along with a study of current and potential efficiencies in softwood sawlog transport; and finally a supply chain management case study. Fibre loss analysed losses occurring in motor-manual and mechanised felling systems, in tree volume above and below 1 m3, and merchandising at either roadside landing or centralised merchandising yard. Fibre volume losses were categorised according to stump wood, felling and crosscut saw kerfs, log trimming allowance, wood left in field, and excessive trimming and removal of utilisable wood. Total losses ranged from 6.7% and 9.9% of total utilisable volume with stumps generally felled 7 cm higher than necessary. Based on the volume of wood not recovered, the revenue lost was R393 million in board products and R166 million in roundwood supply from plantations annually. The second study found a wander ratio of 1:1.2. In terms of predicting travel speeds of primary transport, gross power rating (kW), payload size (m3), extraction distance (m) and slope (%) variables were included. Skidder payloads were found to be approximately 50% of potential design loads. Truck travel speed predictor variables included Visual Condition Index (VCI), road width, average gradient, percentage of maximum load and truck maximum power. Applying multivariate analysis the predictor variables were reduced to road width and percentage maximum load, and a multiple linear regression equation was produced with an adjusted r2 of 0.52. Analysis found that overloading of trucks was a common occurrence. The Case Study required the current forest road network to be repeatedly refined through road decommissioning and selected upgrades over which the timber resource is subsequently flowed to the processing plant. Based on sequentially improved truck speeds, skidder efficiency and fibre use the Net Present Value (NPV) of the various projects, production costs and available timber resource use were quantified. The supply chain was analysed by investigating the effect downstream efficiency improvements have on financial returns over one rotation. NPV results ranged from approximately R40 million to R300 million. The scenario associated with the highest NPV used the most improved road network, highest possible transport speed, and motor-manual felling, cable skidder extraction, merchandising yard and optimal skidder and transport performance. The lowest NPV yielding scenario is associated with an abridged road network, low secondary transport speed, cable skidder extraction, mechanised felling, roadside merchandising, and normal skidder and transport performance. Examination of the individual factors found that road network; secondary transport speeds and performance had a significant effect. Harvest system had no significant effect. A limitation of this study was that only the forest to mill supply chain was analysed. Extending the supply chain to the mill and onto the final customer the benefits to the entire chain are expected to increase further. This gap in knowledge is a likely follow-up study.