Two fast-growing Indian species, Melia composita Benth. and Eucalyptus tereticornis Sm., which have different sets of physical properties, were dried together in a vacuum press dryer(VPD) under two drying conditions,i...Two fast-growing Indian species, Melia composita Benth. and Eucalyptus tereticornis Sm., which have different sets of physical properties, were dried together in a vacuum press dryer(VPD) under two drying conditions,i.e., above boiling point(ABP) and below boiling point(BBP). The ABP and BBP conditions were maintained by keeping the temperature constant at 75 ℃ and maintaining two pressure levels: 300 mm of Hg(ABP) and 450 mm of Hg(BBP). In order to understand pressure conditions at the core during vacuum drying, a cylindrical brass pipe was inserted in both wood cores and attached with pressure gauges placed outside of the VPD. The results indicate that the Melia wood core attained equilibrium pressure immediately with the pressure of VPD, while Eucalyptus attained it very slowly, reaching equilibrium at later stages of drying when cracks and checks advanced to the core.The drying rate was higher for Melia than Eucalyptus under both drying conditions. The drying rate of Melia(ABP) was higher than Melia(BBP), however, the drying rate for Eucalyptus(ABP) was not significantly different from the BBP drying rate.展开更多
【目的】应用电阻断层成像法、应力波断层成像法和阻抗仪法对活立木树干腐朽程度进行检测和定量表征,判断3种方法的可靠性,为野外立木健康情况检测提供基础数据和理论依据。【方法】在黑龙江省哈尔滨市东北林业大学试验林场内,选取水曲...【目的】应用电阻断层成像法、应力波断层成像法和阻抗仪法对活立木树干腐朽程度进行检测和定量表征,判断3种方法的可靠性,为野外立木健康情况检测提供基础数据和理论依据。【方法】在黑龙江省哈尔滨市东北林业大学试验林场内,选取水曲柳和北京杨各25株(15株腐朽,10株健康)共50株100个截面,采用PICUS Tree Tronic型树木电阻断层成像仪、Arbotom应力波断层成像系统和Resistograph针式阻抗仪检测及木芯质量损失率估测4种方法对断面腐朽程度进行检测和定量表征。以木芯质量损失率计算的样木腐朽程度(E_s)为真值,利用最小二乘法分别建立电阻测定的腐朽程度(E_d)、应力波测定的腐朽程度(E_y)及阻抗仪测定的腐朽程度(E_z)与真值(E_s)之间的线性关系。【结果】电阻断层成像、应力波和阻抗仪3种无损检测方法能在不同腐朽程度上表征活立木木材质量损失率;从整体上来看,电阻检测和应力波检测结果与腐朽程度真值的拟合程度低于阻抗仪检测结果与腐朽程度真值的拟合程度;从不同腐朽阶段来看,在E_s<30%时,E_d和E_s的相关系数最高(R=0.823,P<0.01);在30%≤E_s<50%时,E_y和E_s的相关系数最高(R=0.658,P<0.01);在E_s≥50%时,E_z和E_s的相关系数最高(R=0.914,P<0.01)。【结论】电阻断层成像法对木材早期腐朽的检测比较敏感,而应力波断层成像法则相对在木材腐朽稍严重时更准确,阻抗仪法在腐朽各个阶段的检测结果都较为准确,且在腐朽严重时最准确,但会对木材造成微损伤。3种无损检测方法均能有效检测活立木腐朽,并有各自的特点,在实际腐朽检测中应根据实际检测需要来选择。展开更多
基金part of M.Sc.dissertation under financial support from ‘‘Forest Research Institute(Deemed)University,Dehradun(India)’’
文摘Two fast-growing Indian species, Melia composita Benth. and Eucalyptus tereticornis Sm., which have different sets of physical properties, were dried together in a vacuum press dryer(VPD) under two drying conditions,i.e., above boiling point(ABP) and below boiling point(BBP). The ABP and BBP conditions were maintained by keeping the temperature constant at 75 ℃ and maintaining two pressure levels: 300 mm of Hg(ABP) and 450 mm of Hg(BBP). In order to understand pressure conditions at the core during vacuum drying, a cylindrical brass pipe was inserted in both wood cores and attached with pressure gauges placed outside of the VPD. The results indicate that the Melia wood core attained equilibrium pressure immediately with the pressure of VPD, while Eucalyptus attained it very slowly, reaching equilibrium at later stages of drying when cracks and checks advanced to the core.The drying rate was higher for Melia than Eucalyptus under both drying conditions. The drying rate of Melia(ABP) was higher than Melia(BBP), however, the drying rate for Eucalyptus(ABP) was not significantly different from the BBP drying rate.
文摘【目的】应用电阻断层成像法、应力波断层成像法和阻抗仪法对活立木树干腐朽程度进行检测和定量表征,判断3种方法的可靠性,为野外立木健康情况检测提供基础数据和理论依据。【方法】在黑龙江省哈尔滨市东北林业大学试验林场内,选取水曲柳和北京杨各25株(15株腐朽,10株健康)共50株100个截面,采用PICUS Tree Tronic型树木电阻断层成像仪、Arbotom应力波断层成像系统和Resistograph针式阻抗仪检测及木芯质量损失率估测4种方法对断面腐朽程度进行检测和定量表征。以木芯质量损失率计算的样木腐朽程度(E_s)为真值,利用最小二乘法分别建立电阻测定的腐朽程度(E_d)、应力波测定的腐朽程度(E_y)及阻抗仪测定的腐朽程度(E_z)与真值(E_s)之间的线性关系。【结果】电阻断层成像、应力波和阻抗仪3种无损检测方法能在不同腐朽程度上表征活立木木材质量损失率;从整体上来看,电阻检测和应力波检测结果与腐朽程度真值的拟合程度低于阻抗仪检测结果与腐朽程度真值的拟合程度;从不同腐朽阶段来看,在E_s<30%时,E_d和E_s的相关系数最高(R=0.823,P<0.01);在30%≤E_s<50%时,E_y和E_s的相关系数最高(R=0.658,P<0.01);在E_s≥50%时,E_z和E_s的相关系数最高(R=0.914,P<0.01)。【结论】电阻断层成像法对木材早期腐朽的检测比较敏感,而应力波断层成像法则相对在木材腐朽稍严重时更准确,阻抗仪法在腐朽各个阶段的检测结果都较为准确,且在腐朽严重时最准确,但会对木材造成微损伤。3种无损检测方法均能有效检测活立木腐朽,并有各自的特点,在实际腐朽检测中应根据实际检测需要来选择。
