基于分形维木材表面粗糙度的研究

应用分形维对木材表面粗糙度特征进行研究。首先，对Sarkar和Chaudhuri提出的分形维计算方法做了改进：其次，以60个树种为研究对象，提取和分析木材表面的分形维数。得出结论：分形维数能够反映木材表面的粗糙程度，可作为木材表面粗糙度的一种度量？     

A Potential Criterion to Evaluate Copper Adsorption in Wood Cell Wall

A gcometrical definition, fractal dimension, was introduced in this study to evaluate copper adsorption in wood treated with copper-containing preservatives. It is based on the assumption that some copper would compete the hydroxyl groups in wood cell wall with water molecules, and therefore influence the fractal dimension of internal wood surfaces revealed by the moisture adsorption in wood. Southern yellow pine (Pinus spp.) specimens were treated with different concentrations of copper ethanolamine (Cu-EA) solution to obtain different copper retention levels. Then the adsorption isotherms of untreated and Cu-EA treated specimens were determined at 4, 15, 30, and 40℃ to provide the source data for fractal dimension calculation. The results showed that, at all temperatures, the fractal dimension of the internal wood surfaces had a decreasing trend with increasing copper retention. That is, the internal spaces in wood become “thinner“ due to the copper adsorption on some hydroxyl groups in wood cell wall. The correlation between the fractal dimension and adsorbed copper ions makes it possible to evaluate the copper adsorption in wood cell wall.     

基于分形理论的木材纹理特征研究

介绍了一种利用自相关函数来估算图像分形维数的方法，并将其应用到木材的纹理分类检测中。实验表明，分形维数值直接反映了木材纹理的粗糙程度，可定性地作为描述木材纹理粗糙度的一种度量。     

The fractal estimation of wood color variation by the triangular prism surface area method

Color variations of the surfaces of fifteen wood species were characterized by fractal dimension of the triangular prism surface area method. Softwood and hardwood indicated apparently different in the mean fractal dimensions of red and green colors. Red color behaved steadier in softwood than in hardwood and green color varied comparatively stronger in hardwood than in softwood. No evident differences between softwood and hardwood were found in the variation of blue color of all the specimens. Following the low-to-high value order of the mean fractal dimensions, three types of combination of red (R), green (G) and blue (B) colors were found: RGB, RBG and BGR. There also existed six types of fractal dimension distribution; namely, plane, included plane, concave, convex, zigzag, and hilly distributions. Fractal dimensions across the grain changed greatly whereas those along the grain became relatively steady. The characteristic difference of color variation was defined for each species, which was inferred to characterize its own unique appearance of surface color. For color matching of wood parts, fractal dimension quantitatively furnishes essential information of color variation in local and overall features. Such evaluation can be efficiently carried out with few measurements along the grain and by detecting a single color (red, green or blue) only. Received 5 May 2000     

木材密度曲线的分形分析

本文对银杏（Ｇｉｎｋｇｏ ｂｉｌｏｂａ Ｌ．）ｘ射线木材密度曲线分形分析,结果表明,银杏木材密度的分形维数约在１．４４３０。分形维数直观地反映了木材密度年轮内和年轮间的变化规律,与年轮宽度有一定的联系,与木材密度本身关系不大。木材密度的分形维数一般由遗传因素控制,不同树种木材分形维数是相对固定的。木质材料的分形研究,是揭示其内在规律的有效方法。     

透明涂饰对木材纹理等视觉特征的影响分析

对5种木材进行聚氨酯清漆透明涂饰处理,借助数字图像处理技术定量检测涂饰前后9种材色和纹理参数的变化:色调、饱和度、亮度、对比度、二阶角矩、方差和、长行程加重因子、分形维数、小波水平能量分布比重.结果表明:透明涂饰总体上有利于增强木材表面的视觉效果,但影响效果视素材的纹理情况而定.素材纹理原本清晰、明显时,其纹理效果略有变化,但并不显著;而原本呈弱纹理及或隐纹理的素材,透明涂饰对改变其视觉效果的影响作用显著.基于参数的t检验结果,饱和度、亮度、方差和3个参数可以作为涂饰对纹理影响性的重要指标,进而建立起反映透明涂饰对木材视觉效果综合影响的坐标公式.     

木材缺陷识别方法的研究

主要研究运用数字图像处理技术对木材表面缺陷的纹理特征进行具体研究的理论方法和可行性,并通过分析比较,探索一个分形理论和小波结合的的处理方案,完善和丰富木材科学理论,提高木材的利用率。     

木材干缩的分形分析

本文通过一个木材干缩实验 ,展示了木材多孔性的分形特征。用银杏 (GinkgobilobaL .)和板栗(Castaneamollissima)木材作试材 ,用逐渐升高温度的方式处理试样 ,同时称重和量取尺寸 ,可以获得不同温度之间的重量和体积变化值 ,由变化值和立方体边长的对数值得直线斜率。直线斜率反映了木材中空隙体积的分形维数。这种方法可以通过不同树种、不同温度状态下木材水分逸出过程空隙空间分形维数的变化 ,分析木材的干缩规律。建议分形理论可成为木材多孔性研究的有效途径     

木材断口分形的初步研究

木材是一种天然的多孔性生物高分子材料,结构复杂且变异性大,所以木材断裂表面定量分析的难度很高,对于木材内部裂纹产生、发展的研究一直没有大的突破.在木材断裂力学的研究中,国内外科学家运用传统的断裂试验方法研究居多,但普遍结论是规律不明显或找不到规律(费本华,1999).木材研究者们一直在寻找一种定量描述木材断裂表面形态的新指标,并希望在此基础上预测木材强度和了解木材断裂机制(Schmitt et al.,1996;Qin et al.,1999).     

Contributions of Extractives and Lignin to the Fractal Geometry of Internal Wood Surfaces

Internal wood surfaces can be treated as fractals, which are between Euclidean geometry and complete randomness. The fractal dimension Dfs is very informative in investigating the roughness of the internal surfaces of wood. In this study, the water sorption isotherms, including adsorption and desorption isotherm, of untreated, benzene-alcohol extracted and delignified (after benzene-alcohol extracted) spruce (Cuninghamia lanceolata) were measured at 30℃. On the basis of these isotherms, the Dfs values were calculated by FHH equation, which is based on multimolecular sorption. The results showed that both groups of Dfs values (respectively calculated from adsorption and desorption isotherms) of untreated, benzene-alcohol extracted and delignified wood have same order, that is, untreated > benzene-alcohol extracted - delignified. Therefore, the conclusion can be made that the benzene-alcohol extractives have significant contribution to the fractal geometry of internal wood surfaces. Lignin also has influ     

热处理对三种木材尺寸稳定性的影响

以落叶松、红橡和奥克榄为研究对象,采用不同的常压蒸汽热处理工艺条件,对照未处理材,研究热处理温度和时间对木材尺寸稳定性的影响。结果表明:热处理温度和时间对木材的尺寸稳定性有显著影响;木材吸湿性随温度提高逐渐降低,当热处理温度上升到一定程度时,尺寸稳定性改善趋缓;随着热处理时间延长,木材尺寸稳定性提高;木材高温热处理后吸湿性和吸水性的改善与木材的密度、结构等物理性能相关。     

提高刨花板尺寸稳定性的研究——刨花预处理和刨花板的后期热处理

以速生意大利杨为材料,对刨花进行预处理后制成脲醛胶刨花板,用未处理刨花制成酚醛胶刨花扳,并进行后期热处理,分别测试它们的尺寸稳定性,结果表明,两种方法都能较为有效地提高刨花板的尺寸稳定性,具可行性,通过合理选择适宜的预处理和后期处理的时间,可以使刨花板的性能达到预期要求。     

Dimensional instability of cement bonded particleboard: contributions to its occurrence

An intensive programme of research has been carried out to understand the dimensional instability of cement bonded particleboard (CBPB) and establish methods of improving its stability. The quantitative appraisal and qualitative interpretation of the instability were through investigations on CBPB, wood chips and cement paste. Aspects studied included the sorption of all three materials, SEM, image analysis and carbonation of CBPB, and stabilisation of CBPB using various pre-treatments. As part of this programme, this paper discusses the occurrence of instability of CBPB. It was found that the movement of CBPB was attributable to the contributions of its components, the distribution of wood chips and cement paste, carbonation, and residual stresses in CBPB. The behaviour of wood chips and cement paste dominated the movement of CBPB, with the effect of wood chips being greater than that of cement paste; but the behaviour of the cement paste dominated the behaviour of CBPB over a prolonged exposure. Carbonation resulted in a significantly irreversible increase in mass and decrease in dimension of CBPB under both constant and changing RH. The distribution of wood chips in CBPB determined that the change between length and width was almost identical due to a random distribution of wood chips on the horizontal surface (about 45° to the longitudinal edge), and the thickness change was much higher than length change due to wood chips almost lying flat (about 11° to the horizontal). The generation and distribution of stresses had a significant influence on the behaviour of CBPB.     

Improvements in dimensional stability and lightfastness of wood by butyrylation using microwave heating

Microwave heating was used as the heat source for butyrylation of wood with the aim of reducing the reaction time. The photostability and dimensional stability of butyrylated wood were also investigated in this study. Chemical changes of wood were confirmed by cross polarization/magic angle spin ¹³C-nuclear magnetic resonance and diffuse reflectance infrared Fourier transform spectroscopy (DRIFT) after butyrylation by microwave heating. Results from DRIFT with the Si-Carb sampling technique revealed that, using microwave heating, a higher degree of butyrylation of maple wood occurred in the middle of the specimen than on the outer surface. The increase in yellowness index of butyrylated wood treated with microwave heating was much less than that of untreated wood after the lightfastness test, indicating that photoyellowing of wood is effectively inhibited by butyrylation using microwave heating. The dimensional stability of wood was also improved after modification.     

无机质复合速生材研究现状与展望

速生人工林种植面积大,生长周期短,在取代天然林资源方面具有得天独厚的产量优势,但存在结构疏松、密度小、强度低等缺陷,导致其使用范围大受限制。使用无机材料对人工速生材进行改性处理可有效提高速生材性能和用途。文中简要总结无机质复合木材制备方法——扩散法、溶胶—凝胶法和真空浸渍法,以及无机材料改性处理对速生木材在力学性能、尺寸稳定性、阻燃性、表面疏水性和表面耐候性方面的改善,以期为人工林速生材无机材料改性提供技术参考。     

基于图像纹理特征的木材树种识别

利用木材图像的颜色、灰度、纹理等内容实现树种的相似性匹配检索,提取色调、饱和度、亮度、对比度、二阶角矩、方差和、长行程加重因子、分形维数、小波水平能量比重共9个特征参数,依据最大相似性数学原理,基于最小差值参数判别法和综合特征阈值法来检索样本.结果显示:基于图像纹理特征能够实现木材树种的检索和识别,综合特征阈值法的检索正确率与唯一性通常要好于最小差值判别法;但当被检索样本图像的纹理较弱或不呈现纹理特征时,检索结果的唯一性并不理想.综合而言,基于图像纹理特征最大相似性的木材树种检索识别较易实现,是一种值得继续发展和应用推广的木材树种识别方法.     

Multiresolutional image analysis of wood and other materials

The gloss of wood is a unique texture compared to that of other materials. To express it quantitatively, two digital-image analyses were performed. One method was multiresolutional contrast analysis, which was the new method developed in this study. The other method was fractal image analysis. Twenty-four specimens, including solid woods, wood-plastic composites (WPCs), printed grains, and granites, were prepared. Digital images of specimens were obtained in five sizes and in two illuminant directions (perpendicular and parallel to the grain). The multiresolutional contrast values of perpendicular illuminated images were calculated and compared among specimens. The result of this quantitative analysis was that the gloss of wood was characterized by bright spots in a relatively small area. Using fractal analysis, the fractal dimension of a digital image was used as an index of brightness changes, not for expressing the self-similarity. These indices showed results similar to those of the multiresolutional contrast analysis.Part of this paper was presented at the 47th annual meeting of the Japan Wood Research Society in Kochi, April 1997     

多尺度分形特征在木材内部缺陷检测中的应用

将数字图像处理与木材检测相结合,对获取的木材图像进行图像处理与分析,获取高质量的木材图像是提高木材检测准确性的重要手段。利用微光摄像机作为图像输入传感器,并最终以数字信号的形式储存在计算机当中。应用数字图像处理技术对采集到的原始图像进行预处理,提高图像的质量,便于后续处理。将预处理后的图像分割成若干个子区域,计算出每个子区域的多尺度分形特征值。实验结果显示,图像中背景部分与边缘部分多尺度分形特征值存在明显差别,可以提取奇异性较大的多尺度分形特征值,他们的集合即为木材缺陷的边缘。     

Improvement of Pinus pinaster wood dimensional stability using cork industry wastes

Summary This article relates to a procedure of preparing solutions for wood treatment by dissolving the condensed waste material from the baking steam of expanded cork board production in organic solvents. These solutions were applied by way of different methods inPinus pinaster wood treatment. The use of these products and methods improved the pine wood dimensional stability giving rise to lower water absorption and swelling. This cork industry waste, is mainly constituted by tannins and waxes, and their solutions are easy to obtain at low cost. A patent application was done.The authors would like to thank the collaboration of our fellow Mr. Paulo Cortiço     

Potassium acetate-catalyzed acetylation of wood: extraordinarily rapid acetylation at 120°C

The catalytic effect of potassium acetate (KAc) on wood acetylation was investigated. Spruce wood specimens were impregnated with KAc and then heated in acetic anhydride at 120°C. The degree of acetylation was evaluated by the weight percent gain (WPG). In the presence of KAc, the reaction time to achieve a 20% WPG decreased by a factor of 200: 2 min was required in the KAc-catalyzed acetylation, while the uncatalyzed acetylation required at least 5 h. The hygroscopicity and dimensional stability of acetylated wood depended on the WPG irrespective of the treatment methods. This fact proved that KAc had no adverse influence on the dimensional stability of acetylated wood. As KAc is a cheap, water-soluble and non-toxic salt it can be a useful catalyst for the extraordinarily rapid acetylation of wood.