Resonance flexural vibration(Fast Fourier Transform, FFT), ultrasonic wave(Pundit) and stress wave(Metriguard) techniques were examined as means of evaluating the static modulus of elasticity (MOE) and predicting the ...Resonance flexural vibration(Fast Fourier Transform, FFT), ultrasonic wave(Pundit) and stress wave(Metriguard) techniques were examined as means of evaluating the static modulus of elasticity (MOE) and predicting the modulus of rupture (MOR) of finger-jointed lumber specimens made with four kinds of Eucalyptus (Eucalyptus. citriodora, E. exserta, E. grandis x E. urophylla and E. grandis). Dynamic MOE was calculated from frequency and time obtained from forced vibrations and sounds induced in the four species of finger-jointed specimens. It was found that correlation coefficients between density and static MOE and dynamic MOE were statistically significant at the 0.01 level. And it was also found that the three nondestructive techniques can provide rapid and accurate means to determine the MOE, and the dynamic MOE was more accurate to predict static MOE than density. But the correlation coefficient between dynamic MOE, static MOE and MOR were lower than results reported by other researchers for solid wood, and were not statistically significant. It can be concluded that the three nondestructive techniques are useful for evaluating the MOE, but not suitable for predicting the MOR of finger-jointed.展开更多
With the analyses of the reasons for the emergence of domestic and overseas markets for forest environmental service and its significance, this paper summarizes the progress in the research on the market and reviews t...With the analyses of the reasons for the emergence of domestic and overseas markets for forest environmental service and its significance, this paper summarizes the progress in the research on the market and reviews the operations of the markets for 4 kinds of forest environmental services that are watershed protection services, biodiversity protection services, carbon sequestration services and landscape services. At the end, the paper discusses the major problems arising in the creation of markets for environmental services and the developing tendency.展开更多
基金This research is supported by ITTO Project PD 69/01 Rev.2(I) "Improved and diversified use of tropical plantation timber in China tosupplement diminishing supplies from natural forests".
文摘Resonance flexural vibration(Fast Fourier Transform, FFT), ultrasonic wave(Pundit) and stress wave(Metriguard) techniques were examined as means of evaluating the static modulus of elasticity (MOE) and predicting the modulus of rupture (MOR) of finger-jointed lumber specimens made with four kinds of Eucalyptus (Eucalyptus. citriodora, E. exserta, E. grandis x E. urophylla and E. grandis). Dynamic MOE was calculated from frequency and time obtained from forced vibrations and sounds induced in the four species of finger-jointed specimens. It was found that correlation coefficients between density and static MOE and dynamic MOE were statistically significant at the 0.01 level. And it was also found that the three nondestructive techniques can provide rapid and accurate means to determine the MOE, and the dynamic MOE was more accurate to predict static MOE than density. But the correlation coefficient between dynamic MOE, static MOE and MOR were lower than results reported by other researchers for solid wood, and were not statistically significant. It can be concluded that the three nondestructive techniques are useful for evaluating the MOE, but not suitable for predicting the MOR of finger-jointed.
文摘With the analyses of the reasons for the emergence of domestic and overseas markets for forest environmental service and its significance, this paper summarizes the progress in the research on the market and reviews the operations of the markets for 4 kinds of forest environmental services that are watershed protection services, biodiversity protection services, carbon sequestration services and landscape services. At the end, the paper discusses the major problems arising in the creation of markets for environmental services and the developing tendency.
