The Experts below are selected from a list of 2946 Experts worldwide ranked by ideXlab platform
Piero Venturi - One of the best experts on this subject based on the ideXlab platform.
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all year round harvesting of short rotation coppice eucalyptus compared with the delivered costs of biomass from more conventional short season harvesting systems
Biomass & Bioenergy, 2004Co-Authors: Ralph E H Sims, Piero VenturiAbstract:Abstract This study attempted to define the optimum harvesting, processing and transport system in terms of the cost per tonne of delivering biomass produced from a commercial short rotation coppice crop to a 10 MW e bioenergy conversion plant 25 km away. Harvesting the crop during one short seasonal period of the year results in the need to store most of the material for between one to 12 months in order to provide a continual supply of feedstock. Storage of large volumes of biomass is costly and also results in dry matter losses over time. An alternative system would be to harvest small areas as required every few weeks throughout the year. This would enable cheaper, lower performance equipment to be used and hence provide a continual supply of biomass feedstock for delivery to the plant. Four systems of conventionally harvesting the biomass during one short seasonal period of 8–10 weeks were compared with two systems of harvesting it continually throughout the year. Whether the biomass is stored on the farms after harvest to allow for transpirational drying or at the plant was also compared. All-year-round harvesting using a simple tractor-mounted Circular Saw showed cost benefits in terms of $/GJ of energy delivered to the bioenergy plant but the performance assumptions made will require confirmation by field monitoring. A sensitivity analysis was conducted on several key parameters.
Luďka Hlaskova - One of the best experts on this subject based on the ideXlab platform.
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AN INNOVATIVE APPROACH TO PREDICTION ENERGETIC EFFECTS OF WOOD CUTTING PROCESS WITH Circular-Saw BLADES
2020Co-Authors: Zdeněk Kopecký, Luďka Hlaskova, Kazimierz OrlowskiAbstract:ABSTRACT In the classical approach, energetic effects (cutting forces and cutting power) of wood Sawing process are generally calculated on the basis of the specific cutting resistance, which is in the case of wood cutting the function of more or less important factors. The aim of the paper is to present a new calculating model using the application of modern fracture mechanics and to compare cutting parameters of native beech, Bendywood and Belmadur. Cutting and feed forces are determined by the application of the Ernst-Merchant theory in the conditions of Circular-Saw blade cutting. It includes the prediction of the shear plane angle for the cutting models, which include fracture toughness in addition to plasticity and friction, broaden possibilities of energetic effects modelling of the Sawing process even for small values of the uncut chip
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cutting test as source of fracture toughness and shear yield strength for axial perpendicular model of wood cutting
Wood and Fiber Science, 2019Co-Authors: Luďka Hlaskova, Ales Solař, Zdeněk Kopecký, Zdeněk PatockaAbstract:The objective of this study was to develop and design a model of calculation of fracture parameters for axial-perpendicular model of wood cutting. Two selected wood species of Central Europe provenance spruce ( Picea abies L.) and beech ( Fagus sylvatica L.) of two different levels of moisture content (w = 8% and 16%) were Sawn. The measurements of energetic effects (cutting power and cutting force) while Sawing wood were carried out on the laboratory stand which simulates conditions of Circular Saw blade cutting. Using the newly designed model, it is possible to determine fracture toughness and shear yield strength only on the basis of the cutting tests. Unknown parameters, which are then applied in the model, were set based on calculation of the forces acting on the workpiece and the tool. Using the measured cutting force and the feed force, other component of the resulting active force were calculated. The computation was based on Ernst-Merchant’s force decomposition diagram. Results confirmed the obvious influence of the anatomical structures and moisture content on the size of fracture parameters.
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fracture toughness and shear yield strength determination for two selected species of central european provenance
Bioresources, 2018Co-Authors: Luďka Hlaskova, Kazimierz Orlowski, Martin Svitak, Zdeněk Kopecký, Tomasz OchrymiukAbstract:When offcut of wood is formed by shearing, Atkins’s analyses of Sawing processes can be applied. Using this modern approach, it is possible to determine the fracture toughness and shear yield strength of wood. This model is only applicable for the axial-perpendicular cutting direction because both of these parameters are suitable for the given direction of cutting edge movement and cannot be considered material constants. Alternatively, these parameters can be recalculated for the perpendicular and axial directions of cutting when the parameters are considered non-variable quantities. The set of data necessary for calculation can be easily obtained while cutting wood with common Circular Saw blades. It is necessary to ensure a minimum of two levels of workpiece height and two diverse levels of feed speed. The main aim was to develop an alternative methodology for simultaneous determination of wood fracture toughness and shear yield strength for two principal directions regarding wood grains on the basis of cutting tests performed during Circular Saw blade cutting for two selected wood species of Central Europe provenance, such as spruce (Picea abies (L.) Karst.) and beech (Fagus sylvatica L.).
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Utjecaj posmične brzine na nastajanje fine prašine tijekom piljenja ploča iverica obostrano obloženih laminatom
'Faculty of Forestry University of Zagreb', 2016Co-Authors: Luďka Hlaskova, Tomasz Rogoziński, Zdeněk KopeckýAbstract:This paper deals with the problems of wood dust production during the Sawing of two-side-laminated particleboards. It points out the dangerous impact of wood dust particles on people´s health and other unfavourable influences in the working environment. The aim of the paper was to introduce the research of dustiness, to determine the content of fine particles in Sawdust and analyse the influence of feed rate on the granularity of Sawdust created in the process of Sawing two-side-laminated particleboards using modern Circular Saw. Sawing parameters were chosen for the optimal cutting speed of the Circular-Saw blade Pilana TFZL, vc = 84.3 m·s-1 and for three feed rates of a workpiece with the cut vf = 10, 15, 20 m·min-1. The collected Sawdust particles were subjected to the particle-size analysis under exactly defined conditions by sieving and the basic granulometric analysis was made. Sieve analysis gives only a general particle-size distribution without any information considering the mass concentration of fine fraction of dust. Therefore, laser particle sizer Analysette 22 Microtec Plus was used to specify details concerning the size of dust particles smaller than 63 μm, which were collected in the bottom collector.U radu se analiziraju problemi nastajanja drvne prašine tijekom piljenje ploča iverica obostrano obloženih laminatom. Upozorava se na štetan utjecaj čestica drvne prašine na zdravlje ljudi i na druge nepovoljne utjecaje u radnoj okolini. Cilj rada bio je predstaviti istraživanja o onečišćenju radnog prostora drvnom prašinom, odrediti sadržaj sitnih čestica u piljevini te analizirati utjecaj posmične brzine na granulometrijski sastav piljevine nastale tijekom piljenja ploča iverica obostrano obloženih laminatom na suvremenoj kružnoj pili. Parametri piljenja izabrani su za optimalnu brzinu rezanja lista kružne pile Pilana TFL, vc = 84,3 m·s-1, i za tri posmične brzine obratka vf = 10, 15 i 20 m·min-1. Analizirane su veličine čestica piljevine pri točno određenim uvjetima prosijavanja te je određen granulometrijski sastav piljevine. Analiza piljevine prosijavanjem daje samo opću raspodjelu veličina čestica, bez informacije o masenoj koncentraciji frakcija fine drvne prašine. Stoga je za detaljnije određivanje veličina čestica drvne prašine manjih od 63 μm koje su prikupljene u kolektoru na dnu sita primjenjen laserski uređaj Analysette 22 Microtec Plus
Per Gren - One of the best experts on this subject based on the ideXlab platform.
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wood chip formation in Circular Saw blades studied by high speed photography
Wood Material Science and Engineering, 2012Co-Authors: Mats Ekevad, Birger Marklund, Per GrenAbstract:Abstract Films of wood-chip formation were captured with a high-speed camera during rip Sawing of wood with a Circular Saw blade. The Saw blade diameter was 400 mm and the rotational speed was 3250 rpm. The Saw blade had four teeth with rake angles of 0°, 10°, 20° and 30° to ascertain the influence of different rake angles. Wooden boards were cut along the side so that the camera could record the cutting sequence without any interference from material between the cutting teeth and the camera. Tests were made for green, dry and frozen green pine boards, for both counter-cutting and climb-cutting cases. In addition, some Mozambican wood species were cut. The films, recorded at 40,000 frames s−1, show the cutting sequence along the trajectory of the tooth in question and the creation of the wood chip. Details such as the compression of the wood chip in the gullet, the movement of the wood chip inwards and outwards in the gullet and finally the exit from the gullet are visible. The chip size and chip movement...
Zdeněk Kopecký - One of the best experts on this subject based on the ideXlab platform.
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AN INNOVATIVE APPROACH TO PREDICTION ENERGETIC EFFECTS OF WOOD CUTTING PROCESS WITH Circular-Saw BLADES
2020Co-Authors: Zdeněk Kopecký, Luďka Hlaskova, Kazimierz OrlowskiAbstract:ABSTRACT In the classical approach, energetic effects (cutting forces and cutting power) of wood Sawing process are generally calculated on the basis of the specific cutting resistance, which is in the case of wood cutting the function of more or less important factors. The aim of the paper is to present a new calculating model using the application of modern fracture mechanics and to compare cutting parameters of native beech, Bendywood and Belmadur. Cutting and feed forces are determined by the application of the Ernst-Merchant theory in the conditions of Circular-Saw blade cutting. It includes the prediction of the shear plane angle for the cutting models, which include fracture toughness in addition to plasticity and friction, broaden possibilities of energetic effects modelling of the Sawing process even for small values of the uncut chip
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cutting test as source of fracture toughness and shear yield strength for axial perpendicular model of wood cutting
Wood and Fiber Science, 2019Co-Authors: Luďka Hlaskova, Ales Solař, Zdeněk Kopecký, Zdeněk PatockaAbstract:The objective of this study was to develop and design a model of calculation of fracture parameters for axial-perpendicular model of wood cutting. Two selected wood species of Central Europe provenance spruce ( Picea abies L.) and beech ( Fagus sylvatica L.) of two different levels of moisture content (w = 8% and 16%) were Sawn. The measurements of energetic effects (cutting power and cutting force) while Sawing wood were carried out on the laboratory stand which simulates conditions of Circular Saw blade cutting. Using the newly designed model, it is possible to determine fracture toughness and shear yield strength only on the basis of the cutting tests. Unknown parameters, which are then applied in the model, were set based on calculation of the forces acting on the workpiece and the tool. Using the measured cutting force and the feed force, other component of the resulting active force were calculated. The computation was based on Ernst-Merchant’s force decomposition diagram. Results confirmed the obvious influence of the anatomical structures and moisture content on the size of fracture parameters.
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fracture toughness and shear yield strength determination for two selected species of central european provenance
Bioresources, 2018Co-Authors: Luďka Hlaskova, Kazimierz Orlowski, Martin Svitak, Zdeněk Kopecký, Tomasz OchrymiukAbstract:When offcut of wood is formed by shearing, Atkins’s analyses of Sawing processes can be applied. Using this modern approach, it is possible to determine the fracture toughness and shear yield strength of wood. This model is only applicable for the axial-perpendicular cutting direction because both of these parameters are suitable for the given direction of cutting edge movement and cannot be considered material constants. Alternatively, these parameters can be recalculated for the perpendicular and axial directions of cutting when the parameters are considered non-variable quantities. The set of data necessary for calculation can be easily obtained while cutting wood with common Circular Saw blades. It is necessary to ensure a minimum of two levels of workpiece height and two diverse levels of feed speed. The main aim was to develop an alternative methodology for simultaneous determination of wood fracture toughness and shear yield strength for two principal directions regarding wood grains on the basis of cutting tests performed during Circular Saw blade cutting for two selected wood species of Central Europe provenance, such as spruce (Picea abies (L.) Karst.) and beech (Fagus sylvatica L.).
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Utjecaj posmične brzine na nastajanje fine prašine tijekom piljenja ploča iverica obostrano obloženih laminatom
'Faculty of Forestry University of Zagreb', 2016Co-Authors: Luďka Hlaskova, Tomasz Rogoziński, Zdeněk KopeckýAbstract:This paper deals with the problems of wood dust production during the Sawing of two-side-laminated particleboards. It points out the dangerous impact of wood dust particles on people´s health and other unfavourable influences in the working environment. The aim of the paper was to introduce the research of dustiness, to determine the content of fine particles in Sawdust and analyse the influence of feed rate on the granularity of Sawdust created in the process of Sawing two-side-laminated particleboards using modern Circular Saw. Sawing parameters were chosen for the optimal cutting speed of the Circular-Saw blade Pilana TFZL, vc = 84.3 m·s-1 and for three feed rates of a workpiece with the cut vf = 10, 15, 20 m·min-1. The collected Sawdust particles were subjected to the particle-size analysis under exactly defined conditions by sieving and the basic granulometric analysis was made. Sieve analysis gives only a general particle-size distribution without any information considering the mass concentration of fine fraction of dust. Therefore, laser particle sizer Analysette 22 Microtec Plus was used to specify details concerning the size of dust particles smaller than 63 μm, which were collected in the bottom collector.U radu se analiziraju problemi nastajanja drvne prašine tijekom piljenje ploča iverica obostrano obloženih laminatom. Upozorava se na štetan utjecaj čestica drvne prašine na zdravlje ljudi i na druge nepovoljne utjecaje u radnoj okolini. Cilj rada bio je predstaviti istraživanja o onečišćenju radnog prostora drvnom prašinom, odrediti sadržaj sitnih čestica u piljevini te analizirati utjecaj posmične brzine na granulometrijski sastav piljevine nastale tijekom piljenja ploča iverica obostrano obloženih laminatom na suvremenoj kružnoj pili. Parametri piljenja izabrani su za optimalnu brzinu rezanja lista kružne pile Pilana TFL, vc = 84,3 m·s-1, i za tri posmične brzine obratka vf = 10, 15 i 20 m·min-1. Analizirane su veličine čestica piljevine pri točno određenim uvjetima prosijavanja te je određen granulometrijski sastav piljevine. Analiza piljevine prosijavanjem daje samo opću raspodjelu veličina čestica, bez informacije o masenoj koncentraciji frakcija fine drvne prašine. Stoga je za detaljnije određivanje veličina čestica drvne prašine manjih od 63 μm koje su prikupljene u kolektoru na dnu sita primjenjen laserski uređaj Analysette 22 Microtec Plus
Ralph E H Sims - One of the best experts on this subject based on the ideXlab platform.
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all year round harvesting of short rotation coppice eucalyptus compared with the delivered costs of biomass from more conventional short season harvesting systems
Biomass & Bioenergy, 2004Co-Authors: Ralph E H Sims, Piero VenturiAbstract:Abstract This study attempted to define the optimum harvesting, processing and transport system in terms of the cost per tonne of delivering biomass produced from a commercial short rotation coppice crop to a 10 MW e bioenergy conversion plant 25 km away. Harvesting the crop during one short seasonal period of the year results in the need to store most of the material for between one to 12 months in order to provide a continual supply of feedstock. Storage of large volumes of biomass is costly and also results in dry matter losses over time. An alternative system would be to harvest small areas as required every few weeks throughout the year. This would enable cheaper, lower performance equipment to be used and hence provide a continual supply of biomass feedstock for delivery to the plant. Four systems of conventionally harvesting the biomass during one short seasonal period of 8–10 weeks were compared with two systems of harvesting it continually throughout the year. Whether the biomass is stored on the farms after harvest to allow for transpirational drying or at the plant was also compared. All-year-round harvesting using a simple tractor-mounted Circular Saw showed cost benefits in terms of $/GJ of energy delivered to the bioenergy plant but the performance assumptions made will require confirmation by field monitoring. A sensitivity analysis was conducted on several key parameters.