杨树微纤丝角的变异及其与木材性质的相关关系

微纤丝角为细胞次生壁S2层微纤丝排列方向与细胞主轴所形成的夹角,与木材的物理性质、力学性质和化学性质都有着直接的关系。应用x射线衍射法测定了7个杨树无性系(14株样木)胸径处各年轮的微纤丝角,并对应分析和测定了各年轮的木材基本密度、纤维长度、纤维宽度和纤维素含量。研究结果表明,杨树微纤丝角在年轮间存在显著差异,其径向变异规律为从髓心向外以微纤丝角逐渐降低,年轮间的平均微纤丝角在7.8旱?8褐洌荒静幕久芏取⑾宋ざ取⑾宋矶群拖宋睾吭谀曷旨湟泊嬖谙灾钜臁O喙胤治霰砻鳎⑾怂拷怯肽静幕久芏取⑾宋ざ取⑾宋矶群拖宋睾看嬖谙灾母合喙毓叵??0.01),相关系数分别为-0.450、-0.586、-0.516和-0.660。回归分析结果表明,多项式方程可较好地描述杨树微纤丝角与所测定的木材性质的关系,相关系数均在-0.45以上(n=125)。本文的研究结果认为,在今后针对杨树材性改良的育种计划中,微纤丝角是一个重要的选育和改良指标。图3表3参34。     

Locating and identifying sound knots and dead knots on sugi by the rule-based color vision system

Knowledge of the occurrence of sound and dead knots on the surface of sugi is important for the classification and application of the material. This study examined a color vision system for detecting sound and dead knots on sugi. The system can be conceptually divided into three components: a CCD-camera scanning system, an image-segmenting module, and a rule-based defect identifying module. The results showed that the potential defect regions could be located by Otsus threshold algorithm in conjunction with t-test analysis. The accuracies of locating sound knots and dead knots were 92.6% and 97.1%, respectively. The rule-based approach was used to identify sound and dead knots and the identifying accuracies for sound knots and dead knots were 92.0% and 94.1%, respectively. The overall detection accuracy of the system was 87.6%. The results indicated that the rule-based color vision system is an efficient means of detecting sound knots and dead knots on sugi.     

Screening method for wood extractives: direct cellulose thin-layer chromatography plate

A method for screening wood extractives was developed using cellulose thin-layer chromatography plate (Cell-TLC) separation and was directly applied to bioassays. Wood meal (60 mesh) from nangka (Artocarpus heterophyllus Lamk) heartwood was extracted with hot methanol. The crude extract was separated using a Cell-TLC plate (50 × 50mm). Two broad bands with R_f values of 0.46 and 0.96 were found, and the bands showed completely different effects against the pest termite Coptotermes formosanus Shiraki and the decay fungus Fomitopsis palustris. The band with R_f 0.46 was preferentially consumed by workers of C. formosanus, and it did not show any growth inhibition against F. palustris when the Cell-TLC plate was directly exposed to the organism. In contrast, the band with R_f 0.96 appeared to repel strongly the feeding by C. formosanus and inhibited the growth of F. palustris. It was concluded that the Cell-TLC system was applicable for screening wood extracts consisting of many compounds.     

木材材性株内径向变异模式初探──Ⅲ.种植密度对湿地松、火炬松木材密度径向变异模式的影响

对两个地区不同种植密度的湿地松、火炬松进行了微密度分析，研究了种植密度对木材密度径向变异模式的影响。主要结果是：种植密度对湿地松和火炬松各密度特征值径向变异模式的影响，主要表现在变异曲线平均水平高低的变动，而对变异曲线形状的影响并不显著。种植密度对湿地松和火炬松各年轮宽特征值径向变异模式的影响，主要表现在年轮宽度RW和早材宽度EW变异曲线平均水平高低的变动和RW、EW与晚材宽度LW变异曲线形状的变动。种植密度对年轮密度RD的影响从年轮内宽度和年轮密度变异曲线平均水平高低两个方面起作用，出现较复杂的情况，并非所有情况下都是单调的正相关。     

日本落叶松自由授粉家系纸浆材材性遗传变异的研究

对12年生日本落叶松自由授粉子代测定林纸浆材材质性状进行了遗传变异分析、遗传参数估计、相关分析及综合评价和选择。结果表明:家系间综纤维素含量、基本密度、早材和晚材纤维长度、早材和晚材壁腔比差异极显著或显著,10g·L-1NaOH抽出物差异也达10%水平显著。各性状受强度或中等强度的遗传控制,对日本落叶松进行家系水平的材性改良具有很大的潜力。木材密度与早、晚材壁腔比、10g·L-1NaOH抽出物呈显著正相关,与综纤维素含量呈显著负相关,与早、晚材纤维长度相互独立;晚材纤维长度与早材纤维长度存在紧密正相关,纤维长度与早材壁腔比存在显著负相关关系,与晚材壁腔比、综纤维素含量和10g·L-1NaOH抽出物相互独立;综纤维素含量与早材壁腔比呈显著负相关,与晚材壁腔比相关不显著;10g·L-1NaOH抽出物与综纤维素含量、早、晚材壁腔比均相互独立。根据对日本落叶松材质性状的综合评价结果,选出最适合作纸浆林培育的249、340、346、217和364号家系。     

中国木材产业规模化经营的战略性思考

归纳了规模经济效应与产业成长的关系,分析了木材产业规模化经营对产业变革的意义;通过对中国木材产业规模化经营现状的分析,指出了当前所存在的问题;最后,就如何实现中国木材产业的规模化经营进行了战略设计,并提出了战略实施的相关支持性条件.     

人造板在压缩载荷下的粘弹性研究及其意义

粘弹性是人造板的重要特性,直接影响饰面人造板的物理力学性能。在总结近几年的有关研究基础上,讨论了人造板粘弹性与饰面板性能的关系。     

大钟寺博物馆钟架的超声波无损检测

利用超声波技术现场测定北京大钟寺博物馆永乐大钟大型木结构钟架的弹性模量，并对其力学强度的变化做出了评估，找出相关规律，为超声波用于古建筑木结构的无损检测提供科学依据。     

再生聚丙烯与木刨花复合材料的密度和木塑比对复合材料主要性能的影响

研究了用异氰酸酯树脂为胶粘剂,木材刨花与回收聚丙烯为主要材料的复合材料的主要力学性能和尺寸稳定性。结果表明,密度对复合材料的性能有很大的影响,密度越大,力学强度越高,吸水厚度膨胀率基本越低;木塑配比对复合材料的力学性能有一定的影响,力学性能均随着配比的增加呈现不同程度的下降趋势;配比对吸水厚度膨胀率影响明显,配比越大,吸水厚度膨胀率越低,且密度大时,影响就越显著。     

A microwave tomographic system for wood characterization in the forest products industry

Abstract

Nondestructive testing and evaluation techniques able to extract information about the internal structure of the samples under test are very important in the wood industry. Microwave imaging systems have been considered for a long time promising apparatuses for this task. In this framework, approaches exploiting the full scattering phenomena for creating images of the distributions of the dielectric properties of the targets have been developed in the last few years. In this paper, a prototype of microwave tomographic system is presented and several experimental validation confirming its suitability for the use in the wood and forest product industry are reported.