桢楠和闽楠木材构造特征对比分析研究

为了掌握桢楠（Phoebe zhennan）和闽楠（Phoebe bournei）的宏微观构造特征及二者的微观解剖构造的差异,并为木材识别与鉴定提供参考依据,对两种木材的宏观和解剖构造特征进行了对比研究。利用生物显微镜、数码显微镜和Image J图像处理软件等对桢楠和闽楠的宏观和解剖构造特征进行了研究。结果表明,在宏观构造上,二者在材色和纹理上存在着一定的差异,其余宏观特征差异均不明显;在微观构造上,二者导管分子的弦向直径、壁厚的差异较为明显,木纤维的腔径、双壁厚和壁腔比的差异较为明显,木射线细胞宽度（细胞列数）也存在一定的差异,其余解剖特征差异均不明显。     

开展木材美学研究拓宽木材解剖学的应用

该文以探索木材解剖学发展的历史与现状为出发点，比较系统地提出了“木材美学”的理念。为了木材美学的长远发展，该文对木材美学的研究内容进行了初步的系统规划，并从木材宏观美学和木材显微美学两个层面探索性地论述了木材美学的研究方法。该文认为，木材美学的研究应从理论和应用两个方面来开展。在理论方面，现阶段需重点研究木材美学元素和木材美学构成原理；在应用方面，首先需要从美学的角度深入研究木材的宏观与微观构造，并在此基础上广泛开展木材美学图案的创作设计和推广应用研究。该文认为，木材美学具有十分广阔的发展空间和非常诱人的应用前景，木材美学的开创与发展将为传统木材学拓展新的研究领域、带来新的发展空间，可望使木材解剖学焕发新的勃勃生机。     

古建用落叶松木材物理力学性能预测及其影响因素

为实现对木结构古建筑的预防性保护,有必要对木构件的材质性能进行及时有效的预测和评价。采取小试样-缩尺-足尺递进的方式,将微钻阻抗仪和应力波检测等无损检测方法与实验室物理力学性能测试相结合,构建并检验了落叶松木材物理力学性能与微钻阻抗值和波阻模量关系预测模型,进而提出了古建用落叶松木材物理力学性能的现场无损检测分析方法。研究结果表明：落叶松小试件密度与微钻阻抗值呈现明显的线性正相关关系,木材密度与微钻阻抗值线性方程相关系数为0.91;落叶松小试样顺纹抗压强度、抗弯强度及抗弯弹性模量与波阻模量呈现较明显的线性正相关关系,木材顺纹抗压强度、抗弯强度、抗弯弹性模量与波阻模量线性方程相关系数分别为0.86,0.74,0.74;通过微钻阻抗仪和应力波检测可推算落叶松木材物理力学性能。利用小试件测试数据所建立的预测方程进行落叶松大试件物理力学性能推算存在一定的误差,其缩尺试件密度和顺纹抗压强度预测值与实际值平均偏差分别为12%和16%,足尺试件密度和顺纹抗压强度预测值与实际值平均偏差分别为16%和17%。现场预测应同时考虑测试路径因素,自心材至边材区域,落叶松木材密度、顺纹抗压强度、微钻阻抗值沿径向...     

木材炭化及其物理力学性能的研究

以水杉、杨木为原料制备炭化木,研究炭化工艺对木材物理力学性能的影响。结果表明：随着炭化温度的升高,炭化木材色逐渐变深,平衡含水率逐渐降低,密度降低,水杉密度由0.428g/cm3减小至0.340g/cm3,杨木密度由0.482g/cm3减小至0.338g/cm3,水杉抗弯强度下降约42.39%,杨木抗弯强度下降约46....     

皂荚木材构造及物理力学性质研究

按照国家标准GB/T 1927-2009采集处理样本,借助光学显微镜和扫描电镜,分别从宏观角度和微观角度研究了皂荚木材的解剖构造;利用木材万能力学试验机,参照现行国家标准对皂荚木材的力学性质进行了测试和分析.结果表明:皂荚木材属于环孔材;轴向薄壁组织丰富,傍管环管束状;木射线纺锤形,多为同型多列.皂荚木材气干密度为0....     

黑樱桃种子休眠机理及处理方法的研究

对黑樱桃种子处理方法进行研究的结果表明,生理后熟和抑制物质的存在是造成黑樱桃种子休眠的主要原因,暖温层积90天后再冷温层积120天可以有效打破种子的休眠,其中暖温层积是种胚后期发育的主要时期,而冷温层积是消除抑制物抑制作用的关键。     

中国栎属木材的构造及物理－力学性质（一）

本文介绍了落叶栎属中的辽东栎、栓皮栎，以及槲树的木材解剖构造与材性测试结果。三种栎木均属环孔材，心边材明显，木射线较宽，薄壁细胞发达，容积重较高，干缩系数也较大，强度指标较高，属于高强度的木材，其中辽东栎的纤维细胞较长，侵填体发达，早晚材的导管直径差异小，顺纹抗拉力最大，栓皮栎的容积重较其它二种为高，干缩系数的差异也较大。     

五种家具常用木材弹性常数及力学性能参数的测定

采用电测法和三点弯曲法对5种家具常用木材的弹性常数及主要力学性能参数进行了试验测定,并根据木材的正交异性原理对试验结果进行了统计分析。对木材物理力学性能参数测定的试验方法进行研究和探讨,为实木家具结构力学设计提供材料性能参考数据。     

热处理升温速率对柞木微观结构和物理力学性能的影响

升温速率对木材热处理的产品性能和反应机制都会产生显著影响,对生产实践操作也具有重要作用,但相关研究十分缺乏。以柞木为试样,在常压过热蒸汽条件下以5,10,15,20和25℃/h的升温速率分别升温至200℃进行热处理。分析处理材的主要化学组分和结构,并测试其主要物理力学性能,探索升温速率对处理材结构和性能的影响,为木材热处理技术的优化应用提供参考。结果表明：热处理升温速率对柞木化学组成和结构都具有显著影响。细胞壁半纤维素含量随升温速率的减小而下降,而木素的相对含量则随着升温速率的减小而提高,纤维素含量受热处理影响很小,但微纤丝结构发生明显变化。不同升温速率水平下热处理柞木的主要性能也呈规律性变化。热处理后柞木的静态与动态弹性模量均有所增加,且都随着升温速率的下降先增大后减小,与微纤丝结晶度的变化趋势高度一致。热处理后柞木的吸湿性随升温速率的减小而逐步下降,并与半纤维素浓度的变化密切相关。综上可见,升温速率是调节热处理柞木性能的有效工艺参数,但试材性能的变化与升温速率之间并非都是线性关系,应根据木材热处理的主要性能需求,结合生产效率和安全性等综合因素确定木材热处理的升温速率。     

中国樱桃花芽分化规律的研究

首次报道了中国樱桃的花芽分化规律.中国樱桃中、短梢上花芽的形态分化开始期早,镜下观察最早出现在5月下旬;长梢上的花芽形态分化晚,可陆续分化到8月中旬.单个花芽分化过程历时约110d,中、短梢上花芽生理分化期在形态分化开始前1个月.     

汉江樱桃优良株系选育

通过对初选优良单株进行立地调查、性状测量、物候记载、区域试验和品质检验,决选出汉江樱桃3个优良株系,其中汉江4号樱桃树形形成快、结果早、果实粒大、早熟、皮薄、味好、产量高、抗逆性强,建议在适宜区域大力推广。     

Effects of early re-spacing on the physical and mechanical properties of Sitka spruce structural timber

The effects of early re-spacing on the physical and mechanical properties of Sitka spruce (Picea sitchensis [Bong.] Carr.) structural-dimensioned timber were studied using material from a fully replicated 57-year-old trial located in Northern Ireland, which had been thinned at age 11 years. Basic density, distortion (spring, twist and bow), modulus of elasticity (MOE) and modulus of rupture (MOR) in bending of structural timber from four different re-spacing treatments (1.83 m × 3.66 m, 3.66 m × 3.66 m, 3.66 m × 5.49 m and 5.49 m × 5.49 m) were compared with those of timber from a control (1.83 m × 1.83 m). Re-spacing intensity had a significant effect on both modulus of elasticity (p = 0.006) and modulus of rupture (p = 0.009), but not on basic density (p = 0.379) or distortion (p > 0.200). Timber from the two widest re-spacing treatments failed to meet the requirements for the C14 strength class, while timber from the control met the requirements for the C16 strength class. Both MOE and MOR were significantly and negatively associated with knot size and frequency, which in turn increased with re-spacing intensity. Overall, re-spacing intensity only explained approximately 10% of the total amount of variation in both MOE and MOR, with most of the variation due to inter- and intra-tree differences within a treatment. Based on these results, re-spacing of Sitka spruce to a residual stand density of less than 900 trees/ha (3.33 m × 3.33 m) is not recommended if the goal of management is to produce C16 structural timber.     

Improving strength grading of timber by grain angle measurement and mechanical modeling

Abstract

Timber strength grading has become a major issue in the European Union during the last years, due to the introduction of the Eurocode 5 and all its related standards. Currently, the most performing strength grading machines are able to locally detect the boards’ knots sizes and positions and interpret this information through adapted grading models. The best lead to improve their accuracy seems to be the introduction of new information about the boards and adapt the mechanical model to take them in account. Small grain angle causes high reduction of clear wood's mechanical properties; local value of slope of grain appears to be of high interest. The aim of this study is to quantify the additional accuracy that grain angle information can bring to an optical scanner used as a strength grading machine. A specific grading model has been developed accordingly, and the results obtained for different machine/model/loading combinations are presented. These results show that slope of grain measurement can significantly improve the accuracy of the optical scanner, for both modulus of elasticity and modulus of rupture estimations.     

A review of measurement methods used on standing trees for the prediction of some mechanical properties of timber

The accurate prediction of the mechanical properties that can be expected from timber from standing trees has many benefits for the growers and processors of trees. It includes support in tree breeding selection, tree processing allocation decisions, site and silvicultural research and processing production planning. A number of methods have been developed over the last few decades with significant interest in the recent past in especially acoustic methods, near-infrared spectroscopy methods and the Australian multi-property measurement system known as Silviscan. This paper reviews the current literature on new and existing non-destructive or limited destructive property measurement methods on standing trees that can assist with the prediction of, in most cases, the modulus of elasticity and modulus of rupture of timber.     

Influence of treatment temperature and duration on selected biological, mechanical, physical and optical properties of thermally modified timber

The impact of heat-treatment temperature (180, 200, 210, 220 and 240°C) and various heat-treatment durations on selected biological, mechanical, optical and physical properties of thermally modified timber (TMT) was determined. The suitability of different measures for prediction of the treatment intensity was also investigated. Resistance to impact milling (RIM), lightness L*, equilibrium moisture content (EMC), and antiswelling efficiency (ASE) were correlated with corresponding fungal resistance achieved by heat treatments. The results show that the decrease in mass by heat treatments is a suitable measurand to describe the treatment intensity, which is a product of treatment temperature and duration, where the impact of temperature is dominant over the impact of time. The properties examined showed a strong reciprocally proportional relationship with the decrease in mass. Different correlations were found for the various treatment temperatures: the higher the temperature applied, the lower the decrease in mass required for an equivalent improvement in certain wood properties, e.g. biological durability, EMC and dimensional stability. However, mass loss by Poria placenta correlated well with RIM, lightness L*, EMC and ASE of the different heat-treated specimens, depending on the heat-treatment temperature. Consequently, a reliable estimation of improved fungal resistance of TMT, as well as quality control of TMT in general, requires certain process information.     

Influence of treatment temperature and duration on selected biological,mechanical, physical and optical properties of thermally modified timber

Abstract

The impact of heat-treatment temperature (180, 200, 210, 220 and 240°C) and various heat-treatment durations on selected biological, mechanical, optical and physical properties of thermally modified timber (TMT) was determined. The suitability of different measures for prediction of the treatment intensity was also investigated. Resistance to impact milling (RIM), lightness L*, equilibrium moisture content (EMC), and antiswelling efficiency (ASE) were correlated with corresponding fungal resistance achieved by heat treatments. The results show that the decrease in mass by heat treatments is a suitable measurand to describe the treatment intensity, which is a product of treatment temperature and duration, where the impact of temperature is dominant over the impact of time. The properties examined showed a strong reciprocally proportional relationship with the decrease in mass. Different correlations were found for the various treatment temperatures: the higher the temperature applied, the lower the decrease in mass required for an equivalent improvement in certain wood properties, e.g. biological durability, EMC and dimensional stability. However, mass loss by Poria placenta correlated well with RIM, lightness L*, EMC and ASE of the different heat-treated specimens, depending on the heat-treatment temperature. Consequently, a reliable estimation of improved fungal resistance of TMT, as well as quality control of TMT in general, requires certain process information.     

两种木材干燥窑窑型结构的分析

本文介绍了两种顶吹型干燥窑的结构特征,测定了通过材堆的气流速度、空气再循环比、壳体与环境温度差和对主要技术经济指标等资料的分析,评估它们结构的优缺点。也探讨了橡胶木的干燥基准和过程自动控制问题。     

丛生竹物理力学性能及其对制造竹建筑材料的影响

研究了两种最重要的丛生竹种云南黄竹和龙竹的物理和化学性能。实验结果表明,黄竹的物理性能,如纵横干缩性等优于龙竹,而且黄竹的力学性能如静曲强度、静曲弹性模量及顺纹压缩与剪切强度也比龙竹高。与建筑用木材相比,两种丛生竹的物理力学性能均达到了建筑材料的性能要求。     

中国木材市场均衡与林业生态建设均衡分析

木材市场受到各种因素的影响,如国内生态保护政策、国际木材贸易、木材消费偏好等方面的影响。本文主要分析国际贸易和以天然林保护为主的生态环境建设对中国木材市场的影响。