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1.
A new method for nondestructive evaluation of solid wood moisture content based on dual-energy X-ray absorptiometry 总被引：1，自引：0，他引：1
This paper presents a new method to determine the moisture content of solid wood based on the principle of dual-energy X-ray absorptiometry. The study investigates the theoretical relationship between X-ray wavelength and mass attenuation coefficients of wood, water, and reference substance. In accordance with this relationship, a theoretically obtained equation is proposed to calculate the moisture content in wood. The proposed equation is compared to experimental results using small blocks of sugi wood, which showed that the change in mass attenuation coefficient of wood with X-ray tube voltage increased with increasing moisture content as expected from the theoretical equation. A regression equation for moisture content estimation was determined based on the experimental results, and the standard error of estimate in the 0–120 % dry-basis moisture content range using the regression equation was determined to be 21.9 % with the most appropriate pair of tube voltages, 15 and 40 kVp. The accuracy of the method will be improved by reducing the duration of X-ray radiography and by increasing the disparity between paired tube voltages. This method has the potential to determine moisture content of solid wood using X-ray without oven-drying or assuming oven-dry density. 相似文献
2.
This study estimates the structure of a forest stand using high-resolution data from digitized aerial photography. The study
area was conducted on the fifteen plots with the size of 20 m × 20 m or 15 m × 15 m taken as samples of sugi (Cryptomeria japonica D. Don) stands. The stand factor was investigated based on its relation with the digitalized number (DN) on the black and
white aerial ortho photos (scale 1:5,000, taken in 1995). We analyzed various stand structure factors and the distribution
of DN from the image data using the Weibull function, which comforms well to every shape of distributions. Using the Weibull
distribution, a significant negative correlation was observed between the quantity of stand factors (Mean DBH and the stand
volume) and the distribution parameterc of DN. A significant positive correlation was also observed between the distribution parameterc of the stand factor (DBH, height and volume) and the distribution parameterc of DN. 相似文献
3.
Hiroshi Matsunaga Rika Shiotari Junji Matsumura Kazuyuki Oda Yasuhiro Utsumi Koichi Yamamoto 《Journal of Wood Science》2006,52(2):95-100
This is the first report to ascertain potassium location in black heartwood of sugi (Cryptomeria japonica). The objective of this study was to understand the distribution of potassium in sugi black heartwood in connection with
anatomical morphology. Scanning electron microscopy with energy dispersive X-ray analysis (SEM-EDXA) was used to investigate
the distribution of inorganic elements, especially potassium. In black heartwood, potassium was detected in all tissues (tracheids,
ray parenchyma, and axial parenchyma), but its concentrations were different in each xylem tissue. Potassium was particularly
accumulated in the droplets in axial parenchyma cells. In addition, calcium was also detected in all tissues. Phosphorus sometimes
existed in the granules in ray parenchyma cells. From optical microscopy, the axial parenchyma cells were observed to be arranged
in a tangential direction on transverse section and the droplets in these cells were distributed in areas of high ash and
green moisture content. For red heartwood, potassium detected by SEM-EDXA was far lower in all tissues than in the black heartwood,
while the trend for calcium was the converse. Potassium in axial parenchyma cells was more abundant in black heartwood than
in typical pale red heartwood. 相似文献
4.
巨尾桉去皮主干含水率分布规律的探讨 总被引：1，自引：0，他引：1
通过对巨尾桉去皮主干含水率的测定和分析表明：其含水率的分布是随着树干上的位置升高而呈直线上升,树干３Ｈ／１０处的含水率最具代表性,１．３ｍ与Ｈ／２处的含水率的均值可为树干含水率平均值 相似文献
5.
6.
Sixteen quarter-sawn boards (100 × 40 mm2) of regrowth Eucalyptus regnans (Mountain Ash) were conditioned to various moisture contents to investigate the effect of mean moisture content on collapse
recovery. The results support the recommendation that boards should be reconditioned at a mean moisture content of between
15 and 20%. It is likely that the actual amount of collapse recovery was nearly as good for moisture contents up to about
25%. The main disadvantage with reconditioning boards with a moisture content of between 20 and 25% was the additional normal
shrinkage that occurs because of the early reduction or removal of drying stresses. The samples in this study were dried under
mild conditions for long periods of time to minimise the presence of moisture gradients. 相似文献
7.
This study deals with the development of a two-dimensional model to simulate the deformations in wood samples during the wood drying process for the evaluation of the drying quality. The samples cut from sapwood of beech were used to analyse the moisture content distribution of the samples at two different drying conditions. A new concept based on a linear difference method was developed to use the moisture content distribution of the samples for the simulation process to predict deformation due to casehardening. The real deformations of the prongs were compared with the simulated ones for further improvements. The results show that the model can be used to simulate the deformations independently from different drying times and drying conditions. A good comparison between real and simulated changes in deformation was found for the drying process at constant climate conditions. The results provide a useful basis for further investigations on the modelling and simulation of the deformation of the samples due to different drying processes. 相似文献
8.
In our previous report, we investigated the effect of the microfibril angle (MFA) in the middle layer of the secondary wall
(S2) on the longitudinal creep behavior of a thin homogeneous earlywood specimen sugi. In the present study, we investigated
the role of moisture on the tensile creep behavior of wood. We discuss the creep behavior of the wood cell wall from the viewpoint
of the composite structure of the cell wall and the properties of the constituent materials. A microtomed thin specimen of
earlywood of sugi (Cryptomeria japonica D.Don) was used for the longitudinal tensile creep test. Creep tests were conducted at three moisture stages (oven-dry, air-dry,
fiber saturation point) over a broad range of MFA. Results showed that the longitudinal tensile creep behavior was highly
dependent on both the moisture content and the MFA. With a small MFA, the variation in the creep function among the three
moisture states was very small. For a large MFA, the variation in the creep function was larger. At low moisture contents,
the magnitude of the creep function was very small, while at high moisture content, it was very large except for the case
of specimens with very small MFA. Those results show that the longitudinal tensile creep behavior was directly affected by
the fine composite structure and the internal properties of the cell wall constituents. 相似文献
9.
S. C. Chafe 《Wood Science and Technology》1985,19(4):329-345
Summary The relationships among collapse, volumetric shrinkage, moisture content and basic density and their distribution within the stem were examined for trees of E. regnans. It was found that collapse and volumetric shrinkage each were significantly related to moisture content (positively), basic density (negatively), and (positively) to the derived values P (per cent of theoretical saturation) and Q (per cent of cell cavity volume containing water). Notwithstanding the inverse association evident between moisture content and density in the living tree, moisture content was shown to be independently related to each of collapse and volumetric shrinkage.Within the stem, collapse and volumetric shrinkage were negatively correlated with height in the tree although the significance of this relationship was qualified by the adjustment for other variables. Samples containing sapwood displayed collapse values significantly lower than heartwood samples. This was reflected in the presence of a positive relationship between collapse and distance from the periphery when all material was considered, but a negative relationship when sapwood-containing samples were omitted. Basic density was positively correlated with height in the tree and negatively correlated with distance from the periphery. Moisture content, P and Q were negatively correlated with both height in the tree and distance from the periphery although the latter relationship for moisture content was dependent on adjustment for density.The highly significant relationship between volumetric shrinkage and collapse suggested that the former could confidently be used in assessing collapse severity. Moisture content was determined to be an independent indirect indicator of collapse whereas basic density, P, Q and green density could all be of indicatory value, especially the last in view of its ease of measurement. 相似文献
11.
Dielectric spectroscopy of Scots pine 总被引：1，自引：0，他引：1
Laura Tomppo Markku Tiitta Tapio Laakso Anni Harju Martti Venäläinen Reijo Lappalainen 《Wood Science and Technology》2009,43(7-8):653-667
Dielectric properties of Scots pine (42 trees) were compared with density, moisture content (MC), and resin acid content (RAC) (of heartwood). The samples were measured in frozen, green, conditioned and non-conditioned dry moisture states to evaluate the potential of dielectric spectroscopy in determining the wood characteristics at different stages of wood processing. Heartwood and sapwood parts of each sample were measured separately, and through-transmission measurement was conducted in longitudinal and tangential direction at frequencies from 1 MHz to 1 GHz. The MC and density correlated significantly with the dielectric parameters in both measurement directions but especially in longitudinal direction. The RAC of the heartwood correlated significantly with tanδ and ε″/(ε′ ? 1) of the green samples measured in the tangential direction at frequencies above 200 MHz. The correlation at 1 GHz was ?0.56 for green samples, ?0.66 for conditioned samples and ?0.61 for non-conditioned samples (P < 0.001, for all). The study suggests that the extractives also affect radio-frequency dielectric responses, which might be used for extractive analyses of pine heartwood. 相似文献
12.
We constructed sugi site index models using digital-terrain-analysis-based environmental factors for Miyazaki Prefecture.
We selected 18 sugi plantation stands which were pure, undisturbed, and over 40 years old, planted with the same sugi-cutting
cultivar, and managed by normal forest operations. The dominant tree in each stand was felled for stem analysis. Site index,
defined here as dominant tree height at 40 years old, was estimated by stem analysis for each stand. Five types of DEMs were
used: 100- and 50-m resolution derived from DEMs published by the Geographical Survey Institute, and 50-, 25-, and 12.5-m
resolution derived from digital contour map manually generated from a 1:25,000 topographic map. A total of 14 indices categorized
into solar radiation index, wetness index, and topographic exposure index were used to model the site index by multiple linear
regression analysis. Through model selection procedures, the best-fitted site index models were selected for each type of
DEM. The most precise model was that of the 12.5-m-resolution DEM (R
2 = 0.692), following the model of the published 50-m-resolution DEM (R
2 = 0.665). Site productivity of sugi was severely limited by direct solar radiation. Soil wetness also affected sugi site
productivity; however, it can only be represented using a high-resolution DEM derived from fine-scale data. Our results suggest
that the 50-m-resolution DEM published by the Geographical Survey Institute can be used for site index modeling. 相似文献
13.
Soichi Tanaka Yuko Fujiwara Yoshihisa Fujii Shogo Okumura Hiroyoshi Togo Naoya Kukutsu Shoji Mochizuki 《Journal of Wood Science》2013,59(5):375-382
For the application of millimeter wave (MMW) technique to nondestructive evaluation of wood, the effect of annual rings on the behavior of a 100 GHz MMW transmitted through wood was examined. The complex amplitude was measured for 2 mm thick flat- (LT) and quarter-sawn (LR) specimens of several species with different annual ring structures at 11 % moisture content, of which the density distribution was measured using X-ray radiography. For the LT specimens of all species and the LR specimens with small density fluctuation or with earlywood width smaller than the wavelength of the MMW (=3 mm), the amplitude and phase of the transmitted wave were similar to those of the wave without a specimen. For the LR specimen with large density fluctuation and with earlywood width close to or larger than the wavelength, the amplitude and phase were different from those of the wave without a specimen. All the measured complex amplitudes were well expressed using a diffraction model. It was concluded that the MMW is deformed by the density distribution, and then its components with periods shorter than the wavelength by diffraction are attenuated. 相似文献
14.
We investigated the effect of provenance variation on cone and seed morphology and germination behaviour under different pre- treatments in Picea smithiana. Three categories of cones were recognized: large (13.18 cm × 3.30 cm 15.42 cm × 4.35 cm), medium (10.85 cm × 3.93 cm 12.18 cm × 3.98 cm) and small (7.69 cm × 3.06 10.98 cm× 3.39 cm). Significant variation was observed for various cone and seed characteristics. Seeds moisture content varied from 44.48% to 56.91%, seed size from 0.64 cm × 0.31 cm (largest seed) to 0.49 cm × 0.10 cm (smallest seed), and the seed weight from 2.45 g per 100 seeds to 1.36 g per 100 seeds on fresh weight basis of P. smithiana. The highest seed germination (72.0±7.53%) at 10°C was observed under chilling treatment in Tapovan provenance, while the minimum (15.0±5.71%) seed germina- tion was recorded at 25°C under control set in Tapovan provenance. Further among all the sources Pandukeshwar consistently had the highest average (38%) percent germination across all treatments. Compared to other temperature regimes and pretreatments, seeds subjected to 10°C and chilling treatment had the highest germination and took the least time for germination irrespective of provenance effects. Altitude (provenance) had little or no relationship with germination following laboratory treat- ments. Seeds from Tapovan provenance subjected at 10°C following chilling treatment may be suggested for further multiplication of this species. 相似文献
15.
Sugi (Cryptomeria japonica D. Don) is one of the most important planted trees in Taiwan. The normal heartwood of sugi has a red to pinkish rose color. Unfortunately, this pleasant appearance is susceptible to discoloration after environmental exposures. This discoloration is a serious defect that decreases the value of sugi products. The objective of this study was to investigate the effects of environmental factors such as moisture, oxygen, and lights of different wavelengths on the discoloration of sugi. The results show that under the combined effects of light and oxygen the color of heartwood changes from red (or rosepink) to bluish green. The color further darkens and eventually turns to black with the presence of moisture. As for the effect of light wavelengths on the discoloration of sugi heartwood, it was found that the red color was enhanced after being irradiated with light of wavelengths above 600 nm. Botha
* andb
* values increased significantly as a result of such exposure. 相似文献
16.
Water stress integral (WSI) is a method of assessing cumulative plant water stress over a chosen period of time. While the technique has been used in other tree species, it has not been applied for reforestation projects. In this study we used the WSI approach for newly planted Douglas-fir in the Pacific Northwest (USA), where the Mediterranean climate, plant community development, and competition for water all play key roles in the success of establishment efforts. In this study, previously reported seedling growth, xylem water potential, and soil moisture data were utilized to provide direct correlations between Douglas-fir productivity, soil water availability and WSI. For each growing season, a strong relationship between WSI and volume growth as well as a strong linear relationship between WSI and soil moisture measured during mid-August was found. On average, for each reduction of 0.01 cm3 cm?3 in soil moisture measured during mid-August, Douglas-fir seedling volume growth decreased by 5.6 and 7.7% in the first and second growing seasons, respectively. Preserving soil moisture until early-August through the judicial application of vegetation management regimes was critical for maximizing stand productivity. Based on these results, a single evaluation of soil volumetric water content during early-August can be used as a predictor of stand productivity during the initial two seasons of forest establishment. 相似文献
17.
This study was carried out to investigate the possibility of calibrating a prediction model for the moisture content and density distribution of Scots pine (Pinus sylvestris) using microwave sensors. The material was initially of green moisture content and was thereafter dried in several steps to zero moisture content. At each step, all the pieces were weighed, scanned with a microwave sensor (Satimo 9,4GHz), and computed tomography (CT)-scanned with a medical CT scanner (Siemens Somatom AR.T.). The output variables from the microwave sensor were used as predictors, and CT images that correlated with known moisture content were used as response variables. Multivariate models to predict average moisture content and density were calibrated using the partial least squares (PLS) regression. The models for average moisture content and density were applied at the pixel level, and the distribution was visualized. The results show that it is possible to predict both moisture content distribution and density distribution with high accuracy using microwave sensors. 相似文献
18.
For reasons of unequal distribution of more than one nematode species in wood, and limited availability of wood samples required for the PCR‐based method for detecting pinewood nematodes in wood tissue of Pinus massoniana, a rapid staining‐assisted wood sampling method aiding PCR‐based detection of the pine wood nematode Bursaphelenchus xylophilus (Bx) in small wood samples of P. massoniana was developed in this study. This comprised a series of new techniques: sampling, mass estimations of nematodes using staining techniques, and lowest limit Bx nematode mass determination for PCR detection. The procedure was undertaken on three adjoining 5‐mg wood cross‐sections, of 0.5 × 0.5 × 0.015 cm dimension, that were cut from a wood sample of 0.5 × 0.5 × 0.5 cm initially, then the larger wood sample was stained by acid fuchsin, from which two 5‐mg wood cross‐sections (that adjoined the three 5‐mg wood cross‐sections, mentioned above) were cut. Nematode‐staining‐spots (NSSs) in each of the two stained sections were counted under a microscope at 100× magnification. If there were eight or more NSSs present, the adjoining three sections were used for PCR assays. The B. xylophilus– specific amplicon of 403 bp ( DQ855275 ) was generated by PCR assay from 100.00% of 5‐mg wood cross‐sections that contained more than eight Bx NSSs by the PCR assay. The entire sampling procedure took only 10 min indicating that it is suitable for the fast estimation of nematode numbers in the wood of P. massonina as the prelimary sample selections for other more expensive Bx‐detection methods such as PCR assay. 相似文献
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