共查询到20条相似文献,搜索用时 46 毫秒
1.
《Wood material science & engineering》2007,2(1):45-53
Samples of nine tropical hardwoods from Peru and sugar maple wood from Quebec were selected for moisture sorption and swelling tests at 25°C. These tests evaluated the fiber saturation point (FSP) by two methods: following adsorption over distilled water, and from the volumetric swelling intersection point. Cold-water and hot-water extractives, sequential cyclohexane, acetone and methanol extracts, ash content, wood density and interlocked grain were also determined on matched samples. The results indicated that adsorption tests over distilled water were not applicable for determining FSP in all wood species. Condensation of water vapor apparently occurred, even though temperature during adsorption was controlled to the nearest 0.01°C. The volumetric swelling intersection point method was judged more appropriate. FSP ranged from 15 to 25% for tropical hardwoods and was 30% for sugar maple wood. FSP was negatively correlated with wood density, acetone extracted fraction, interlocked grain and ash content. These parameters each exerted similar effects on variability in FSP. 相似文献
2.
《Wood material science & engineering》2013,8(1):45-53
Abstract Samples of nine tropical hardwoods from Peru and sugar maple wood from Quebec were selected for moisture sorption and swelling tests at 25°C. These tests evaluated the fiber saturation point (FSP) by two methods: following adsorption over distilled water, and from the volumetric swelling intersection point. Cold-water and hot-water extractives, sequential cyclohexane, acetone and methanol extracts, ash content, wood density and interlocked grain were also determined on matched samples. The results indicated that adsorption tests over distilled water were not applicable for determining FSP in all wood species. Condensation of water vapor apparently occurred, even though temperature during adsorption was controlled to the nearest 0.01°C. The volumetric swelling intersection point method was judged more appropriate. FSP ranged from 15 to 25% for tropical hardwoods and was 30% for sugar maple wood. FSP was negatively correlated with wood density, acetone extracted fraction, interlocked grain and ash content. These parameters each exerted similar effects on variability in FSP. 相似文献
3.
4.
5.
6.
基于优化卷积神经网络的木材缺陷检测 总被引:1,自引:0,他引:1
针对深度学习中的卷积神经网络算法,在木材无损检测过程中存在缺陷定位不准确、缺陷轮廓和边界信息不完整、识别精度需进一步提高等问题,利用非下采样剪切波变换最优稀疏表示特性,以及简单线性迭代聚类算法能很好地保持像素紧凑度和图像边界轮廓的优点,设计了一种优化的卷积神经网络算法,以提高木材无损检测的准确率。首先采用非下采样剪切波变换对采集的木材图像进行简单预处理,保留木材图像的缺陷特征不丢失,降低图像处理的复杂度以及运算量;然后利用卷积神经网络对木材图像实现深层次的算法设计,同时应用简单线性迭代聚类算法对初步模型进行增强改进,提取出相对准确的木材缺陷轮廓;最后通过反复调整参数和调试优化器,优化卷积神经网络算法的收敛速度,提高学习和运算效率,完善卷积神经网络对木材缺陷轮廓的提取,在降低运算复杂度的同时,提高其精度,具有良好的鲁棒性。相比径向基函数(RBF)神经网络、向后反馈-径向基函数(BP-RBF)混合神经网络和卷积神经网络,本算法对木材缺陷具有更好的识别效果,其识别准确率达到98.6%左右,且识别时间相对更短。 相似文献
7.
An automated wood texture recognition system of 48 tropical wood species is presented. For each wood species, 100 macroscopic texture images are captured from different timber logs where 70 images are used for training while 30 images are used for testing. In this work, a fuzzy pre-classifier is used to complement a set of support vector machines (SVM) to manage the large wood database and classify the wood species efficiently. Given a test image, a set of texture pore features is extracted from the image and used as inputs to a fuzzy pre-classifier which assigns it to one of the four broad categories. Then, another set of texture features is extracted from the image and used with the SVM dedicated to the selected category to further classify the test image to a particular wood species. The advantage of dividing the database into four smaller databases is that when a new wood species is added into the system, only the SVM classifier of one of the four databases needs to be retrained instead of those of the entire database. This shortens the training time and emulates the experts’ reasoning when expanding the wood database. The results show that the proposed model is more robust as the size of wood database is increased. 相似文献
8.
《Scandinavian Journal of Forest Research》2012,27(4):374-383
In the forestry–wood chain the concept and the technologies of traceability are in a mature development phase. Important advances in marking and reading techniques have been made in different parts along the forestry–wood chain. For Swedish sawmills the most critical information gap is located between the log sorting station and the saw intake, where the forest log batch identity disappears and the logs are mixed according to different sorting criteria. This study utilizes radiofrequency identification tags for automatic log marking/reading to develop a traceability system for logs, which is free of marking/reading, between the log sorting station and the saw intake, i.e. the fingerprint method. The originality of the fingerprint approach rests on the hypothesis that logs are separate entities with individual features. The results show that the log parameters and the search algorithm developed, combined with the negative influence of the measurement uncertainty due to bark thickness and bark damage, made it possible to achieve an individual separation for 57% of the tested logs. 相似文献
9.
At present, a carbon (C) content of 50% (w/w) in dry wood is widely accepted as a generic value; however, few wood C measurements have been reported. We used elemental analysis to investigate C content per unit of dry matter and observed that it varied both radially and vertically in boles of two old-growth tree species: sugar maple (Acer saccharum Marsh.) and giant sequoia (Sequoiadendron giganteum (Lindl.) Bucholz). In sugar maple there was considerable variation in tree ring widths among four radii for particular annual layers of xylem, revealing that the annual rate of C assimilation differs around the circumference and from the base of each tree to its top, but the observed variation in C content was unrelated to diameter growth rate and strongly related to the calendar year when the wood was formed. Carbon content in sugar maple wood increased in an approximately linear fashion, from < 50 to 51% from pith to cambium, at both the base and top of the boles. In giant sequoia, C was essentially constant at > 55% across many hundreds of years of heartwood, but it declined abruptly at the sapwood-heartwood boundary and remained lower in all sapwood samples, an indication that heartwood formation involves anabolic metabolism. Factors that may be responsible for the different C contents and trends with age between sugar maple and sequoia trees are considered. Tree-ring data from this study do not support some of the key assumptions made by dendrochronology. 相似文献
10.
A rapid,automated flaw segmentation method using morphological reconstruction to grade wood flooring
Region-Growing Algorithms(RGAs) are used to grade the quality of manufactured wood flooring. Traditional RGAs are hampered by problems of long segmentation time and low inspection accuracy caused by neighborhood search. We used morphological reconstruction with the R component to construct a novel flaw segmentation method. We initially designed two template images for low and high thresholds, and these were used for seed optimization and inflation growth, respectively. Then the extraction of the flaw skeleton from the low threshold image was realized by applying the erosion termination rules. The seeds in the flaw skeleton were optimized by the pruning method. The geodesic inflection was applied by the high threshold template to realize rapid growth of the flaw area in the floor plate, and region filling and pruning operations were applied for margin optimization. Experiments were conducted on 512×512, 256×256 and 128×128 pixel sizes, respectively. The 256×256 pixel size proved superior in time-consumption at 0.06 s with accuracy of 100%. But with the region-growing method the same process took 0.22 s with accuracy of 70%. Compared with RGA, our proposed method can realize more accurate segmentation, and the speed and accuracy of segmentation can satisfy the requirements for on-line grading of wood flooring. 相似文献
11.
[目的]针对现有图像处理方法分割立木精度低的问题,提出一种基于改进ResNet-UNet的立木图像分割方法,实现对图像中立木的精确分割.[方法]将拍摄得到的立木图像输入ResNet-UNet深度学习融合网络模型,初步得到较精确的立木分割图;结合自制的后期处理方法对该分割图进行优化处理,准确分割出立木形状.ResNet-... 相似文献
12.
基于模糊聚类分析的木材缺陷CT图像分割 总被引:1,自引:0,他引:1
为了提高木材的利用率,在木材加工之前对木材缺陷CT图像进行分割,将节子和空洞等缺陷分割出来,通过观察缺陷的位置便于工人师傅下锯。利用计算机断层扫描(CT)技术获取木材缺陷图像,将数字图像处理技术与模糊聚类算法相结合,在标准的模糊C均值算法的基础上改进,采用半模糊聚类的分析方法对木材缺陷图像进行分割检测。实验结果表明:基于半模糊聚类的图像检测方法在木材图像检测上取得了较好的效果,缺陷边缘处很平滑,细节保留完整,更多的保留了边缘上的信息。从而证明了半模糊聚类分析法在木材缺陷CT图像处理方面具有可行性。 相似文献
13.
Differences in sensitivity to soil conditions across tree species and developmental stage are important to predicting forest response to environmental change. This study was conducted to compare elemental concentrations in leaves, stems, and roots of (1) sugar maple (Acer saccharum Marsh.) seedlings vs. mature trees and (2) mature sugar maple vs. mature American beech (Fagus grandifolia Ehrh.) in two sites that differ in soil base saturation and pH. Both sites are located in Huntington Forest, NY, USA; one site (hereafter ‘H’) has higher soil pH and Ca, Mg, and Mn concentrations than the other site (hereafter ‘L’). Sugar maple growth at H (14.8 cm2 year−1 per tree) was much greater than at L (8.6 cm2 year−1 per tree), but the growth of beech was not different between the two sites. Leaves, roots, and stem wood of mature beech trees and sugar maple seedlings and mature trees were sampled for nutrient analysis. Foliar Ca, K, and Al concentrations were positively correlated with soil elements, but Mn concentrations were negatively correlated. Sugar maple differed more than beech between sites in foliar K and Mn concentrations. Root Mg and P concentrations reflected soil chemistry differences, in contrast to foliar concentrations of Mg and P, which were indistinguishable between the sites. In sugar maple, seedlings differed more than in mature trees in nutrient concentrations in roots, especially for Mg and Mn. Although beech was not as responsive to nutrient availability as sugar maple in foliar and root nutrient concentrations, Ca and Mg concentrations in beech wood were higher in H (52% higher for Ca and 68% higher for Mg), while sugar maple did not differ between sites. Sugar maple regeneration failure on acidic soils in the same region is consistent with our finding that sugar maple seedlings were very sensitive to nutrient availability. This sensitivity could ultimately contribute to the replacement of sugar maple by American beech in regions of low pH and base cations if base cation leaching by anthropogenic deposition and tree harvesting continues. 相似文献
14.
15.
16.
在用X射线检测木材缺陷的过程中,很重要的一步就是对图像中的缺陷的提取和分割,其处理的效果直接影响到后面的缺陷识别的正确性。主要是针对木材X射线图像对比度差的特点和固有的模糊性,利用模糊C均值聚类的方法对木材X射线图像进行分割处理,为后续的提取出木材缺陷工作打下基础。 相似文献
17.
The role of test block placement within a modified decay jar system for promotion of fungal pigments was investigated. Beech and sugar maple blocks were inoculated with common pigment producing fungi and incubated for 10?weeks. Blocks were placed either below the vermiculite or resting on its surface; no feeder strips were utilized. Amount of pigmentation differed with block placement with Arthrographis cuboidea (on sugar maple and beech) and Xylaria polymorpha (only on sugar maple) producing more pigment when placed on the surface of the vermiculite. The differences in pigmentation, however, were not necessarily due to moisture content differences within test blocks, as moisture content did not vary significantly by block placement with A. cuboidea. Results indicate that placement of wood above vermiculite may increase pigmentation; however, reasons for the increase appear to differ among fungi. 相似文献
18.
针对传统区域生长方法识别实木地板节子存在准确率低且速度慢的问题,运用TRIZ中矛盾解决理论分析与物质——场分析,提出一种结合分水岭、区域生长以及边缘检测的新的实木地板节子识别算法。算法首先将原图像转换为灰度图像;其次,运用形态学分水岭的方法对灰度图像进行分割;再次,选取满足条件的种子区域进行区域生长,得到节子区域;最后,运用Sobel算子对图像进行梯度运算,并找到节子的边缘。仿真实验表明,该算法较传统方法能够找到更合适的种子区域和区域生长的阈值,实现了对节子的快速、完整提取,节子分割平均用时60ms,平均辨识准确率在90%以上。 相似文献
19.
20.
Influence of moisture sorption history on the swelling of sugar maple wood and some tropical hardwoods 总被引:2,自引:0,他引:2
Roger E. Hernández 《Wood Science and Technology》1993,27(5):337-345
Summary Samples of nine tropical hardwoods from Peru and sugar maple wood from Quebec were selected to perform moisture sorption tests associated with swelling tests at 25 °C. The results demonstrate that, for a given equilibrium moisture content, tangential and radial dimensions, and hence the volume of wood, are greater after desorption than after adsorption. The importance of these differences, so-called second-order effects of moisture sorption, varied with the species and with the direction of swelling. These effects are proportionally greater in the tangential direction of wood than in its radial axis. Finally, two types of samples showed similar swellings for three equilibrium moisture contents.The author wishes to thank Professor M. Goulet for his support and help. This research was supported by the Canadian International Development Agency and the Natural Sciences and Engineering Research Council of Canada 相似文献