Rotational performance of traditional Nuki joints with gap II: the behavior of butted Nuki joint and its comparison with continuous Nuki joint

Nuki joints are often used in oriental carpentry. Various types of Nuki joints have different structural characteristics, which needs further investigation. This article proposes a theoretical model for butted Nuki joints and reports verification of the model by 21 full-scale tests. We then compare the mechanical behaviors of butted Nuki joints with continuous Nuki joints by using the theoretical models proposed in this article and in a previous report. The results show that the initial stiffness and moment resistance of butted Nuki joints are much lower than continuous joints, and the butted Nuki joints have larger initial rotation without any moment resistance. The results of this study help us understand the structural behavior, and to estimate the structural characteristics of butted Nuki joints when carrying out the structural analyses.     

An evaluation of the small-scale sawmilling and timber processing industry in northern Vietnam and the need for planting particular indigenous species

This paper reports findings of surveys into small-scale sawmilling and timber processing in Phu Tho Province and the Tam Dao National Park buffer zone in northern Vietnam. The objective of these surveys was to examine the extent to which small sawmills and timber processors utilise farm-grown timber, so as to explore the prospects for expansion of farm-grown timber markets. The operational scope, supply chain and value chain of the industry are reported. Resource availability and current and future perspectives are discussed. Timber prices were found to vary greatly between species and study areas. Species most in demand by enterprises are Artocarpus heterophyllus, Melia azedarach, Manglietia conifera, Acacia spp., Chukrasia tabularis and Erythrophloeum fordii. Small-scale sawmilling and timber processing activities fit well with rural communities in Vietnam and have potential for further development if current constraints can be overcome. Further tree planting is needed to meet the presently unsatisfied timber demand and to create income and employment. Information from sawmillers and timber processors suggests the types of species that farmers should be considering for their plantings.     

The REDD/Carbon Market Offsets Debate: Big Argument,Small Potatoes

Both proponents and opponents of using forest carbon markets to pay for Reductions in Emissions from Deforestation and forest Degradation (REDD) have exaggerated their importance. The resources mobilized by the principal drivers of deforestation—beef, soy, palm oil, and wood products—dwarf all REDD funding, even if one only counts exports of these commodities from tropical forest countries. By far the largest part of that REDD money has come from public funding, not carbon markets, and even that has mostly been “voluntary market” funding, not offsets usable for regulatory compliance. While substantial carbon market growth is projected, the rules of most of those markets do not allow the use of REDD offset credits. It is important for those on both sides to realize that they are talking about an alternative that is very small, compared both to other kinds of REDD funding and to the scale of finance operating to drive deforestation. Far more urgent than continuing the debate about whether forest carbon markets are a solution or a threat, is the question of how to change the behavior of the industries and commodities driving deforestation so as to move them to a zero-deforestation business model.     

The role of trees in sustainable agriculture — an overview

Agroforestry in the Australian environment has potentials to rehabilitate land from further degradation; improve agricultural productivity; produce timber; and contribute to diversification and increase in farm income. These benefits are examined using available information from research. The level of adoption of agroforestry by Australian farmers for these purposes is also determined. Summaries of research results provide the basis for advice that scientists can offer to farmer and decision makers.     

几种木材处理方式对云南松人工林的云南松材剖面密度影响的研究

采用热压、水煮和汽蒸对云南松人工林的云南松材进行了处理,对经处理的云南松材剖面密度进行了测定。结果表明,3种处理方式对其云南松材的剖面密度都有影响。其中水煮处理的影响最大;而3种处理方式对云南松材不同部位的剖面密度的影响也不同,以对端部的影响为最大。     

常用竹材使用性能分级评价研究

采用竹材直径、竹壁厚度、竹材天然耐久性能和可处理性能为指标,将每项指标设定四个等级及相应等级下的参考分值,对17个竹种在作材用的功能上进行使用分级,并将分级结果与竹的传统用途进行比较,结果表明这种分类方法有一定的可取性,就是得分高的竹材较适合作材用竹。     

杉木林间伐强度材种出材量和经济效果的研究

1976年6月在江西省奉新县磉下林场10年生杉木林中进行抚育间伐强度试验,1996年10月结束,历时20年.采用定位研究,随机区组设计,3次重复.研究揭示:不同间伐强度林分材积依照径级的分布规律呈正态分布,有一个峰值,偏向小径级位置.林分大径材材积及其比例随间伐强度增加而显著增加,小径材则相反,间伐强度之间中径材材积无显著性差异.林分活立木出材量大致占总出材量90%～95%,间伐木和枯损木约占5%～10%,间伐不能有效提高林分总出材量及伐后20年间定期增加值.强度间伐能比对照极显著增加大径材出材量,小径材则相反,中度和弱度间伐大径材出材量比对照也有显著增加,但间伐强度之间中径材出材量无显著性差异.30年生林分总产值、活立木产值及其20年间定期增加值均以强度＞中度＞弱度＞对照;强度间伐极显著大于对照,中度和弱度间伐显著大于对照,间伐林分活立木产值及其定期增加值显著大于对照的原因系大径材产值增加的结果.伐后20年间,依照林分年平均产值及其定期年平均值的变化,从经济上分为4个时期,即上升期、高峰期、高峰延续期、下降期.研究提出以木材产品市场价值及其相应经济效果确定杉木林主伐期,可望获得较高经济效益.并以此提出不同间伐强度林分主伐期:对照24 a、弱度和中度30 a、强度30～35 a.     

泡桐材色变异规律的研究

泡桐材色在树干或侧枝圆盘年龄上从里向外呈现“深-浅—深”的径向变化形式。在不同高度上,泡桐材色随树高增加逐渐变浅,在靠近梢部时又有变深的趋势;泡桐枝材的材色变化规律与干材相似,可以用6年生的成熟枝材来评估干材材色。     

双梁抛木器落抛时惯性力对抛木影响的研究

双梁抛木器是一个由承托梁和滑木梁组合而成的承载梁，失稳后，承托梁向后翻转，原木在重力作用下沿滑木梁抛下，由于结构所致，原木抛落时产生一个惯性力。实验结果表明，该力的存在并不会导致失抛。由落抛时间引起的水平距离很小，不影响小门板的开启长度。     

江西省竹材建筑模板业的回顾与展望

本文回顾了江西省竹材建筑模板业十余年的发展历程，分析了发展各阶段中生产工艺、原材料利用率、质量控制等诸多方面的问题。同时展望了江西省竹材建筑模板业的发展前景提出了发展方向及对策，对管理部门的决策和推动企业进一步的发展有积极的借鉴作用。