木材导热系数的理论表达式(英文)

本文从木材的微观结构出发，应用物理力学导出木材弦向和径向导热系数的理论表达式 ，计算20种左右木材导热系数并与相同条件下的实验值比较，平均误差在5%附近，两者吻合 程度令人满意。     

木材干燥理论在木材加工技术中的应用分析

在木材加工技术中,木材干燥理论包括木材平衡含水率理论、木材传热理论、木材水分扩散理论以及木材干燥应力与应变理论。以上几大理论涉及到木材的干燥处理、加工、维护以及强度设计。木材干燥理论在木材加工中具有十分重大的意义。     

水曲柳木材裂纹尖端应力强度因子研究( 英文)

该文研究了水曲柳 (FraxinusmandshuricaRupr .)木材发生Ⅰ型断裂时裂纹尖端的应力场应力强度因子的情况 .借助美国大型通用有限元分析软件NASTRAN计算出裂纹尖端附近的应力 ,并通过GRAFTOOL软件对数据进行后期处理 ,画出裂纹尖端附近的应力强度因子分布图     

分形理论在木材科学与工艺学中的应用

分莆是一种新兴的基础理论,将在成为木材科学研究的有效手段之一,本文阐述了分形理论的基本概念、原理和应用,着重介绍分形在木材解剖学、木材物理力学和加工过程中的应用前景。     

毛白杨无性系木材基本密度遗传变异研究(英文)

对河北、河南、山东、甘肃的４块毛白杨无性系测定林中约１００个无性系进行了木材基本密度的测定，对木材基本密度在地点和无性系间的遗传变异进行了研究．结果表明：毛白杨无性系的木材基本密度平均值为０．４３６３ｇ／ｃｍ３，木材基本密度在地点和无性系间均存在极显著差异．木材基本密度的无性系重复力为０．８２～０．９１，属于受遗传控制较强的材性性状．对生长和材性的相关研究表明，木材基本密度与生长性状（包括胸径、树高和材积）一般存在显著的负相关，但不同地点上表现为不同的正或负的相关关系     

中国人工林展望:林木培育、木材质量及其合理利用(英文)

随着天然林保护工程的实施 ,我国木材资源结构正在进行由主要利用天然林木材到利用人工林木材的转变 .由于人工林木材所含幼龄材比例相当高 ,木材资源结构的变化反过来必将对我国的木材加工工业及林产品工业带来一系列影响 .该文综述了我国木材资源的现状 ,比较了人工林幼龄材与天然林成熟材的木材基本特性 ,探讨了人工林木材性质特征与营林培育的关系 ,阐述了木材质量与不同最终用途之间的关系 ,并对加强开展人工林木材性质的研究提出了几点建议     

木材改性的基础与理论模式

木材是一种优良的天然材料,具有其他材料无法比拟的特性比强度高,加工容易,电绝缘性、隔热性、隔音性好,视觉特性、触觉特性、听觉特性、嗅觉特性及环境调节特性好,价格便宜等,自古为人类所使用.     

氧化反应对热处理固定杉木压缩木材的影响(英文)

该研究的目的是明确氧化反应对热处理固定杉木压缩木材的影响 .首先 ,饱水状态的杉木试件在热压机中被径向压缩约 50 % ,然后压缩试件被分别放在一个普通烘箱 (有氧热处理 ,空气的压力为大气压 )和一个真空干燥箱中 (真空热处理 ,空气压力很低 ,约 0 .0 75MPa)进行热处理 ,两种热处理都设置了 5种温度包括 140 ,160 ,180 ,2 0 0 ,2 2 0℃以及不同的时间 .同时进行热处理的还有一些绝干的对照试件 ,用来测定不同热处理过程中的重量损失率 (WL)和抗收缩率 (ASE) .研究结果如下 :( 1)热处理过程中氧气的存在大大提高了热处理的效率 ,在 2 2 0℃时有氧热处理约 2 .5h后 ,压缩木材的RS(回复率 )达到 0 ;但在真空热处理时 ,在 2 2 0℃时加热约 30h后 ,压缩木材的回复才能基本被固定 .( 2 )氧化并不是压缩变定的固定、木材重量的损失或尺寸稳定性提高的必不可少的条件 ,氧气的存在几乎对RS和WL以及ASE和WL间的关系没有影响 ,但对RS和ASE间的关系有一些影响 .( 3)T T平面中的RS等值线 ,Δt一定回复率和温度下两种热处理所需时间的差值 )和温度间的关系 ,以及由于氧化反应而引起的热处理效率增加的系数 η清楚地反映了氧化反应对热处理固定杉木压缩木材的效率的影响     

木材流体渗透理论与研究方法

为较全面系统地了解木材流体渗透理论研究现状,从流体在多孔介质内的主要类型与流动理论、流体在木材内的主要流通通道及木材流体渗透性研究的主要理论与试验方法等几方面进行综合概述,提出木材流体渗透性理论研究的主要发展方向.试验观察应采取更先进的手段,动态观察流体尤其是液体渗透木材的整个连续过程,并构筑更合理的木材流体简化结构渗透模型,以较少的参数反映更完整的流体渗透途径;理论研究应借鉴木材干燥过程中应用较成熟的传质传热模型,建筑多孔材料如水泥、石、砖等的渗透性研究,土壤流体渗透性及地下石油流体渗透性研究方面应用较成熟的理论和方法,并拓宽木材渗透性的研究对象,建立符合木材非稳态渗透实际过程的二维或三维理论模型,以更逼真地模拟木材流体渗透过程;2种方法结合起来,定性和定量完整描述木材流体渗透机制.     

Brief report on theoretical research upon wood thermal property

lntroductionThermaIpropertiesofwoodsuchasspecificheat,thermalconductivityandsoonareparameterswhichisrequiredinscientificresearchandheattreatmentofwood.BecausewoodisakindofnaturaIpolymerorganismwhosechemicaleIementandmicrostruc-tureareverycomplicated,it'sverydif=ficulttostudyitsthermaIpropeFtytheoreticalIy,therefOre,foraImostonecentury,itwasbymeansofexperimentthatthescientistsathomeandabroadstudiedthethermalpropertyofwooddirectIy(Dunlap19121KotImann1968,Cheng1985,Gao1985,Zhang1986)Buttheq…     

Study on the specific heat of wood by statistical mechanics

Introduction12Sincewoodisanaturalmacromolecularorganism,andchemicalcomposition,structureandbiologicalcellstructureofwoodareextremelycomplicated,thesecausegreatdifficultytothetheoreticalstudyonthespecificheatofwood.Sofar,anyresearchachievementhasnotbeenreportedonit.Wetrytheoreticallytofindouttheinternalrelationandessentiallawsbetweenthespecificheatofwoodandthemicrostructureofwood,revealtheinternalfactorsandtheexternalconditionsofaffectingthespecificheatofwood,andfinallyderiveatheoreticalexpress…     

Liquid water diffusivity of wood from the capillary pressure-moisture relation

This study focuses on liquid water transport in wood above the fiber saturation point in the nonhygroscopic region. The liquid water transport of hygroscopic porous materials including wood is usually described by Darcy’s law. It requires knowledge of capillarity and intrinsic and relative permeabilities. In this study, the capillary pressure-water relation and relative permeability were investigated using experimental data for wood available in the literature. The performance of three models (Brooks-Corey model, van Genuchten model, and Durner’s bimodal pore-size distribution model) was investigated for the capillary pressure-water relation. These models have advantages in that each shape parameter has qualitative physical meaning for the pore-size distribution. Most species had unimodal pore distributions except for aspen, which had a bimodal pore distribution. The van Genuchten model represented the capillary pressure-water relation better than the Brooks-Corey model. Durner’s bimodal model was found to be the most appropriate for the capillary pressure-moisture relation of aspen. The relative permeability was calculated by using Mualem’s model, which was compared with the value from the Couture model. From the results, the liquid water diffusivity divided by intrinsic permeability of wood was estimated. This approach may be promising for adopting the liquid water diffusivity for the numerical simulation of drying and sorption, although there might be considerable variation within and between trees.     

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。     

Thermal constants of wood during the heating process measured with the laser flash method

The thermal diffusivity, specific heat, and thermal conductivity of 13 species of wood were measured by means of the laser flash method to investigate the thermal properties of wood during the heating process. The temperature ranged from room temperature to 270°C in air or under vacuum. The thermal diffusivity varied little during the heating process up to 240°C. The values in air were larger than those under vacuum. There was a linear relation between the specific heat and the ambient temperature, and the specific heat under vacuum was larger than that in air at high temperature. The thermal conductivity increased with density and the ambient temperature. To discuss the effects of the atmospheric conditions on the thermal constants of wood, a theoretical model of thermal conductivity was proposed and its validity examined, where the wood was assumed to be a uniformly distributed material composed of cell walls and air.Part of this paper was presented at the 47th annual meeting of Japan Wood Research Society at Kochi, April 1997     

THE EFFECT OF WOOD SURFACE ROUGHNESS OF DIFFERENT SPECIES OF TREES ON WOOD COLOR IN WORKING OPERATION

Woodsurfaceroughnessisthemicrogeometrypropertycomposedbyalittlespacingandpeak-tovalley.Generallythesurfaceroughnesswascomposedbytheworkingmethodandotherfactorst123.Woodsurfaceroughnesswasnotonlyanimportantindexwhichmeasuredthesur-facesmoothextentofwoodproductandtheworkingqualitybutalsothewoodsur-fitceroughnessaffectedwoodsurfacefeel--lngandpsychologicalfeeling[3'4,lo,ll:.Th,'quantitativesurftlceproPertyparametersweretheimportantpartwhichmarkedthewoodsurfacevisualpsycho1ogicalmagni-tude,whichha…     

Thermal and hydrophobic properties of glycerol stearate-modified Pinus radiata wood

Glycerol stearate was synthesized by esterification with non-toxic,inexpensive glycerol and stearic acid.The composite of glycerol stearate and Pinus radiata wood was prepared by vacuum impregnation.By Fourier transform infrared(FTIR)analysis,there was the generation of new C=O stretching vibration band of glycerol stearate in comparison with stearic acid.This confirms that glycerol stearate was successfully synthesized.The weight gain,FTIR spectrum and morphological analyses of the composite indicate that glycerol stearate was impregnated into the interior lumina of the cells.Thermal analysis showed that the maximal degradation temperature of the composite was 42℃higher than untreated wood.Contact angle images indicated that the value of the composite was134.2°.Hydrophobicity(the repulsion of water)of the composite was stronger than glycerol stearate,which a large number of hydroxyl of wood reacted with the oxygen-containing groups of glycerol stearate,improved hydrophobicity and thermal stability,thereby enhancing the potential application of P.radiata wood.     

传统木材生产与效益木材生产

本探讨了传统木材生产和效益木材生产的区别，并从生产方式和经营模式上具体论述了传统木材生产和效益木材生产。     

Thermal conductivity and diffusivity of wood

Summary Transient simultaneous measurements of thermal conductivity and diffusivity of Swedish wood have been performed with the plane source technique on oven-dry hardwood (birch) samples at room temperature and at 100 °C. The influences of temperature, density, porosity and anisotropy on thermal conduction were investigated. The measurements were done in longitudinal (parallel to the grain) and transverse (intermediate between radial and tangential) directions. As the temperature increased from 20 to 100 °C, the thermal conductivity of each sample increased slightly for both longitudinal and transverse directions. The effect of density and porosity on the thermal conductivity may be related to the presence of other scattering mechanisms such as voids and cell boundaries. It seems that the dominant mechanism of heat transfer across the cell lumina in these types of wood is the heat conduction through the voids. An attempt was made to explain the behaviour of the effective thermal conductivity by adopting a model based on the ratio between heat conduction in parallel and serial layers of gas, liquid, and solid phases. Received 7 May 1997