劈裂材检量方法的商榷

GB／T144-2003《原木检验》对劈裂材的检量方法进行了规定,但在实际生产中,这些规定有不尽合理之处。本文对其进行了分析,并提出了修改建议。     

浅谈节子在锯切用原木工作中的检量和计算

文内介绍了活节、死节、腐朽节、漏节的形成及特征、并根据国家木材标准将节子的检量和计算作了总结说明.     

一种新的针叶材自动识别方法

提出通过横切面显微图像对针叶材树种进行计算机识别的方法。该方法通过提取图像的PCA特征,生成特征树,然后采用SVM对样本进行分类。使用8种针叶材,每种12个样本,并采用留一交叉验证,对图像的分割方法、最近邻与SVM分类算法和不同范数距离下的识别效果进行试验。结果表明通过部分木材微观的纹理结构进行木材识别的可能性。     

原木评等中漏节计算问题的探讨

本探讨了现行原木缺陷标准中对漏节的检算方法，认为统计漏节个数时不应把漏节数目相加。且漏节尺寸与树干内腐不成正比。     

针叶材在超细粉碎过程中细胞壁断裂的理论计算

将针叶材的超微结构破坏分为细胞壁间分离和细胞壁断裂两种形式。在制备其超细木粉过程中,涉及到针叶材细胞的破壁力计算时,提出以细胞壁中存在大量的原生细观缺陷作为已存在的裂纹,将单一细胞壁看作是带有裂纹体受拉应力的平板,利用弹塑性断裂力学中J积分与积分路径无关这一常数的性质,避开裂纹尖端的弹塑性区域进行理论计算,应用J积分与应力强度因子在平面应力下的关系,计算出针叶材细胞壁断裂韧性的大小,并将不同针叶树种的木材细胞断裂韧性数值与其相应的细胞壁抗拉强度实验结果相比较,得出以此理论计算木材细胞断裂韧性值较为合理,表明利用J积分计算木材细胞壁断裂韧性这一方法是可行的。     

杉木人工林无节材培育技术研究

采用目标树培育技术,通过人工修枝的方法来培育杉木人工林无节木材,以提高南方杉木木材的市场价值。为了形成一套较为完整的杉木无节材培育技术,按照不同的保留密度和修枝强度等因素进行试验设计。根据1999-2003年连续4 a的观测数据,分析结果表明,杉木8年生前林分的保留密度对杉木生长无显著影响,在1 800株.hm-2范围内可以采用较大的保留密度;不同的修枝强度对杉木生长造成显著影响,随着修枝强度的增大,杉木的树高、胸径和冠幅生长都显著下降,考虑到修枝效果和杉木生长两方面因素,以10 cm的修枝强度(修枝的基础粗度)最好。     

论木材检验中造材后的量材改锯问题

本文论述了木材检验中造材后量材改锯中存在的问题。如原木的一断面腐朽为薪材,而另一端为优良断面的木材,如何进行量材改锯等等。并提供了木材改据参考一览表。     

原条量材设计中数据库技术的应用

针对原条量材设计赋权有向图理论中标号法需要大量检索原木价格表这一问题，通过了按树种分别建立数据库，运用ADO(Active Data Object)数据对象访问技术进行编程，解决了原本价格检查难的问题。     

原条量材设计中木材等级的确定

针对采用标号法进行原条量材设计时原木等级难确定这一问题 ,提出利用双向链表存储木材缺陷的信息 ,编制特定函数的办法 ,来解决这一问题     

原条量材设计优化软件的研制

根据原条量材设计赋权有向图优化理论数学模型 ,按标号法对有向图求解的思路编制了原条量材设计优化软件。该软件采用的用户界面是对话框类型 ,利用双向链表存储常见木材缺陷的信息 ,并把缺陷的判定作为一个函数来使用 ;利用数据库技术把原木价格表按树种分成若干个数据库存储起来 ,并使用ADO数据对象访问技术作为检索数据库的方法。该软件可在Windows9X、WindowsXP、Windows2 0 0 0等操作系统下运行 ,速度较快 ,能够满足量材需要 ,并对改变目前靠经验量材的生产现状 ,使原条量材设计工作更加科学、合理 ,具有一定的指导意义。     

A decision support tool approach based on the Electre TRI-B method for the valorisation of tropical timbers from the Congo Basin: an application for glulam products

An alternative approach to the formal management strategy of tropical timber species from the Congo Basin was investigated. It focused on the development of glulam, with an aim to specify a decision support model for the valorisation of tropical timber species considered for use in these products. There were 76 forest species analysed regarding ecological, engineering and social criteria according to their major uses. The Electre TRI-B multicriteria sorting method was used. The main result was a new and robust classification tool of timber species from the Congo Basin, corresponding to their multicriteria consensus degree. The potentials of the new grouping system were analysed. Species that meet a great majority of criteria were identified. They were highly suitable for sustaining the market position of glulam products. Implementing this strategy may significantly improve the management and increase the value of the timber species from the Congo Basin, while preserving endangered species.     

Regeneration and structure of mixed conifer forests under single-tree harvest management in the western Bhutan Himalayas

We examined the regeneration and structure of mixed conifer forests under single-tree harvest management in western Bhutan. Sixteen 900 m² (30 m × 30 m) plots were sampled at four Forest Management Units (FMUs; Chamgang, Gidakom, Paro-Zonglela, and Haa-East) representing the forest type, including half the plots in single-tree harvest stands and half in unlogged stands. In addition, we solicited information on traditional forest management practices from informants using survey questionnaires and collected tree species data from felling records from respective local forest offices. Rural timber demand is concentrated on the removal of straight and well-formed bluepine trees for beams, planks, and scaffolding. Single-tree harvest, however, has not significantly altered stand structures from unlogged stands. Similarly, tree regeneration is not different when comparing single-tree harvest and unlogged stands, except at Chamgang FMU, where seedling densities were generally higher in harvested stands than in unlogged stands. These results indicate that single-tree harvest is not detrimental to regeneration and utilization of mixed conifer forests in western Bhutan.     

Shape and distribution of knots in a sample of picea abies logs

In an attempt to develop a better understanding of the effect of knottiness on the yield of logs for sawn timber products, the present study examines the position and geometrical characteristics of 429 knots found in seven Norway spruce (Picea abies (L.) Karst) middle logs from southern Finland. The raw data used in this study were in the form of coordinates of points located on the knot surface recorded in a cylindrical (R, L, T) reference frame. The data were smoothed using a non linear three‐dimensional model. A curvature analysis of the knot pith was used to differentiate the curved and straight portions of the knots. This analysis made possible calculation of knot angles, symmetry, ovality and volume. The major finding of this study is the uneven distribution of knots around the log circumference. Nearly 50% of the total knot volume was concentrated in one‐third of the log facing the south‐east. Knots were also more prominent in higher portions of the logs studied. These observations support the argument that the uneven distribution of knots offers potential for improving the grade yield of timber sawn from trees harvested in high‐latitude countries.     

Effects of thinning and pruning on knots and lumber recovery of Taiwania (<Emphasis Type="Italic">Taiwania cryptomerioides</Emphasis>) planted in the Lu-Kuei area

This study investigated the effects of various thinning and pruning methods on the knots (number and size) and lumber recovery from Taiwania (Taiwania cryptomerioides Hay.) plantation trees. The results showed that heavy thinning caused more knots and larger-diameter knots than medium or no thinning; moreover, pruning caused fewer numbers of knots and smaller-diameter knots than no pruning. Better-quality Taiwania trees occurred with the no-thinning/no-pruning treatments, as shown by analyzing the knots, although the results also showed that the healing process seemed to have produced not completely clear wood during the 9 years after the pruning treatment. The thinning intensity slightly enhanced the lumber recovery of logs. Pruning did not affect lumber recovery from taiwania trees and logs. Thinning increased the lumber recovery per tree due to an increase in the diameter at breast height.     

当前发展我国竹材工业的几点思考

分析了竹材的特点和竹材工业利用的现状及当前面临的市场萎缩、竞争加剧、产品价格偏低、企业负担过重等方面的挑战：提出了转变观念、继续大力开发与大工业配套的竹材产品、发展竹家具和竹地板生产、研究科学、合理利用竹材的新途径、减轻税赋等方面发展竹材工业的新建议。     

浅议福建省木材凭证运输管理

阐述木材凭证运输管理的重要作用 ,分析面临的新问题 ,提出加强木材运输检查监督的思路。     

森林案件涉案伐倒木材积惟一性的探讨

材积是盗伐、滥伐等森林案件定性和处罚的主要依据,要求具有惟一性。用马尾松、杉木和杨树的伐倒木资料,分别按不同的计算方法计算其材积,结果表明:在3种树种中,中央断面区分求积式(区分段段数为5以上)的材积都最接近实际材积,误差也都较小,可作为森林案件中涉及伐倒木材积的惟一认定结果。     

四川主要针叶树种含碳率测定分析

应用湿烧法对四川13个主要针叶树种不同器官的有机含碳率进行了测定,同时利用生物量资料对林分平均含碳率进行了分析。实验结果表明:各树种林分平均含碳率分别为落叶松0.5259、火炬松0.5262、华山松0.5437、马尾松0.5144、湿地松0.5216,云南松0.5281、油松0.5314、柏木0.5211、杉木0.5365、柳杉0.5479、水杉0.5489、冷杉0.5050、云杉0.5160;种内各器官的含碳率变动系数在1.90%~5.96%之间;器官含碳率的种间变动系数在2.28%~5.37%。针叶树种器官碳的平均含碳率普遍高于阔叶树种0.18%~7.45%;相应的针叶林分的平均含碳率也高于阔叶林。     

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.