微机识别国产阔叶树材的研究

本文提供了苹果Ⅱ型微机的木材识别系统,兼有中文、英文两个检索程序。数据库中有阔叶树材的42个组合特征(其中33个复合特征,19个非复合特征)。除提供了检索、数据修改、新增树种程序外,还有恢复至前一次检索状态和提供检索结果,5个树种以下的种间相异特征表。     

木材横纹压缩过程构造学计算机视觉系统构建

在木材横纹压缩大变形领域中,连续跟踪木材横纹压缩过程,研究其构造学微观形态的变形规律,构建了一套完整的硬件系统和软件系统,为木材科学在木材横纹压缩大变形的定性分析方面步入定量描述奠定了理论基础。     

Soil pore identification with the adaptive fuzzy C-means method based on computed tomography images

The complex geometry and topology of soil is widely recognised as the key driver in many ecological processes. X-ray computed tomography (CT) provides insight into the internal structure of soil pores automatically and accurately. Until recently, there have not been methods to identify soil pore structures. This has restricted the development of soil science, particularly regarding pore geometry and spatial distribution. Through the adoption of the fuzzy clustering theory and the establishment of pore identification rules, a novel pore identification method is described to extract pore structures from CT soil images. The robustness of the adaptive fuzzy C-means method (AFCM), the adaptive threshold method, and Image-Pro Plus tools were compared on soil specimens under different conditions, such as frozen, saturated, and dry situations. The results demonstrate that the AFCM method is suitable for identifying pore clusters, especially tiny pores, under various soil conditions. The method would provide an optional technique for the study of soil micromorphology.     

基于多目标遗传算法的管孔组合特征识别

提出一种管孔组合方式的自动识别方法.提取木材显微横切面的边缘后,基于类圆区域面积直方图,通过最大类间方差将封闭区域分为2类,将导管与其他形状相似、大小不同的组织分开；同时,引入封闭区域平均面积作为另一目标函数.最后采用管孔集邻接度来判断管孔的组合方式.试验表明该方法能够对各种导管的分布和组合获得满意的分割效果,并给出管孔的组合方式.     

Multi-Objective Genetic Based Pore Combination Recognition

This paper proposes an automatic method of pore combination recognition,which is an important feature to hardwood recognition.After extracting edge from wood microscopic cross-section, based on area histogram of the similar circle regions,the method classifies all regions into two classes with maximum between-class variance,so as to distinguish the pore from other textures,which are similar in shapes but different in sizes.Meanwhile, second objective function about average area of closed regions is used to improve the pore segmentation performance.At last,the method uses adjacency degree of pore set to judge pore combination.The experiments demonstrate that the task of pore segmentation can be completed successfully for all kinds of pore distribution and combination,and also the correct combinations of pores are given.     

A fuzzy-logic-based expert system for near-view scenic beauty evaluation of hinoki forest

Scenic quality must be assessed in forests for which recreational opportunities have become more important then traditional wood products. Current assessment methods focus on quantitative evaluations that provide digital information to the users. Usually, people prefer more explicit information (i.e., categorical data) than detailed quantitative data on scenic quality assessment. This paper employed fuzzy-logic terminology to define the scenic information of forests, and then tried to develop an expert system for evaluating scenic quality based on fuzzy reasoning. Results showed that a fuzzy-logic-based expert system using a qualitative model labeled with linguistic terms, makes scenic beauty evaluation intuitive and understanding easy by viewing the categorical physical features of forests. This research developed a methodology of building an expert system in this area. It is capable of providing an efficient and useful tool for forest recreation users and forest managers.     

基于机器视觉的木材特征提取与树种识别研究综述

我国是木材及木制品加工大国,近年来家具、装修等市场需求的快速增长推动了木材加工行业的发展。由不同树种制作而成的木材材料性质与价值大相径庭,因此准确识别木材树种具有重要意义。相较于传统人工识别,基于机器视觉的木材树种识别大幅度提高了准确率。文中通过分析近5年来木材识别领域的相关文献,总结了木材特征提取的相关技术与树种识别的各种方法,提出要深度融合木材的多个特征并加强各种算法间的配合使用;此外,针对机器视觉在木材树种识别中的应用普遍停留在学术研究阶段的问题,提出木材树种识别应向装备数字化方向发展,以期提高木材树种识别的工作效率。     

Analysis of the pore-size distribution and fiber saturation point of native and thermally modified wood using differential scanning calorimetry

The aim of this paper was to investigate pore-size distributions in the nano-diameter range of wood and their alteration due to thermal modification of wood using thermoporosimetry, and to find out what consequences can be derived regarding the biological durability. Thermoporosimetry is a technique that is based on the measurement using differential scanning calorimetry (DSC). The method is based on the fact that frozen water contained within small pores is at elevated pressure and therefore has a depressed melting temperature as a function of the appropriate pore diameter. In addition, the fiber saturation points (FSP) were determined by DSC. The former were performed in an isothermal-step method and the latter using the continuous heating-up method. Native and thermally modified twin samples of Norway spruce (Picea abies (L.) Karst.), Sycamore maple (Acer pseudoplatanus L.) and European ash (Fraxinus excelsior L.) were analyzed. The results clearly show that the pore shares of wood for the measurable diameter range between 4 and 400 nm decrease considerably in all studied wood species due to thermal modification of the wood. Furthermore, thermal modification of wood leads to a decreased FSP for all studied wood species. For evaluation as well as reproducibility of the results of pore-size distribution and FSP, the consideration of sensible heat and specific heat of fusion plays an important role. If this is not done, it can lead to misinterpretations.     

基于DNA的木材识别新技术发展与应用

介绍了基于DNA方法的木材识别新技术在国内外的研究进展,在分析现存技术问题的基础上,提出完善DNA方法在木材识别领域应用的建议.为开辟木材识别的新途径,保护木材资源、推进木材合法贸易提供技术支撑.     

细胞壁空隙对木材性能及加工利用的影响

细胞壁空隙是木材水分横向传输的重要通道,是影响木材干燥速率、木材改性效果的重要因素.针对细胞壁空隙的研究不仅是对木材本身构造和性能的进一步了解,更是对木材物理和化学加工基础的深入诠释.文中概述木材细胞壁空隙的组成、分类、具体尺寸等,归纳其对木材物理力学性能及加工利用的影响,总结目前木材细胞壁空隙构造研究尚存在的问题并提...     

Characterisation of pore size distributions in variously dried Pinus radiata: analysis by thermoporosimetry

The pore size distribution and networks within the wood cell wall tend to decrease on drying wood from its green state having implications for water ingress and further processing such as in preservative treatment. Thermoporosity measurements using differential scanning calorimetry have been applied to determine the pore size distribution of green Pinus radiata wood and how well this pore network is retained on supercritical fluid (SCF) dewatering compared with kiln drying. Generally, in green sapwood, the majority of bound water was distributed in pore sizes less than 50 nm diameter with only a small proportion present in pore sizes between 50 and 200 nm. On SCF dewatering, most bound water was found to reside in pore sizes <20 nm, consistent with dewatered wood being at fibre saturation point (FSP). Generally, on rewetting dewatered, kiln- or oven-dried wood, proportionately less bound water was present compared with green wood, consistent with reduced pore sizes and network accessibility for water ingress. Furthermore, on rewetting, there were distinctions between earlywood and latewood (LW) sections with the LW sections having a statistically greater proportion of water occupying smaller-sized pores (<20 nm). There was also greater variability of pore size distributions on sample rewetting, inferring drying does not uniformly reduce pore size volumes. Analysis suggests the extent of variability was generally less in the rewetted dewatered wood sample compared to kiln- or oven-dried samples, which may be a consequence of SCF drying only to FSP.     

Effect of pore conformation on dielectric anisotropy of oven-dry wood evaluated using terahertz time-domain spectroscopy and eigenvalue problems for two-dimensional photonic crystals

To clarify the effect of pore conformation on the dielectric anisotropy of wood, the relative permittivity along the longitudinal and tangential axes of flat-sawn oven-dry specimens of 12 different wood species was measured using terahertz time-domain transmission spectroscopy and compared with the values calculated using the eigenvalue problem for two-dimensional photonic crystals. The measured dielectric anisotropy, which is the ratio of the relative permittivity along longitudinal axis to that along the tangential axis, was well explained by the calculated value. It was concluded that the ratio of tangential to radial widths of wood pores affects the relative permittivity along the tangential axis, and that the dielectric anisotropy decreased with an increase in the ratio. This discussion can also be applied to the relative permittivity in frequencies below 0.15 THz. These findings show promise as a new method for evaluating the porous structure of wood.     

基于图像纹理特征的木材树种识别

利用木材图像的颜色、灰度、纹理等内容实现树种的相似性匹配检索,提取色调、饱和度、亮度、对比度、二阶角矩、方差和、长行程加重因子、分形维数、小波水平能量比重共9个特征参数,依据最大相似性数学原理,基于最小差值参数判别法和综合特征阈值法来检索样本.结果显示:基于图像纹理特征能够实现木材树种的检索和识别,综合特征阈值法的检索正确率与唯一性通常要好于最小差值判别法;但当被检索样本图像的纹理较弱或不呈现纹理特征时,检索结果的唯一性并不理想.综合而言,基于图像纹理特征最大相似性的木材树种检索识别较易实现,是一种值得继续发展和应用推广的木材树种识别方法.     

木材细胞壁与木材力学性能及水分特性之间关系研究进展

阐述了木材细胞壁微纤丝角、结晶度、纹孔和化学组分等对木材力学性能的影响规律,针对木材的水分特性重点归纳了纹孔和抽提物对木材渗透性的影响机制,并对未来细胞壁微观研究发展趋势进行了总结,旨在为木材细胞壁相关研究提供借鉴。     

Basic study on contour tracing method in softwood cell contour extraction

The application of digital image analysis to calculate the parameters of softwood cells and to understand their microstructure is of importance in the area of basic micro-wood research such as wood anatomy. In order to obtain cell parameters, the most important part is to separate the cells from their background in an image, which is accomplished by drawing cell contours. In this study, a contour tracing method based on digital image binarization is introduced to extract the contours of softwood cells. As well, a comparison with other traditional methods is included. The results show that using this contour tracing method, clear and complete contours can be obtained, which solves the problems of traditional methods where sharp corners and turning points in an image could not be addressed.     

Changes in micropores in dry wood with elapsed time in the environment

To investigate the changes in microstructures of wood with elapsed time in the environment, CO₂ adsorption onto dry wood was measured at ice-water temperature (273 K) for samples aged from 0.1 years to over 1000 years. The micropore size distribution was obtained using the Horvath-Kawazoe method. Micropores smaller than 0.6 nm in wood decreased in number with elapsed time in the environment, and a negative correlation was found between cumulative pore volume for pores smaller than 0.6 nm and elapsed time in the environment. Cumulative pore volume in the 1000-year sample was almost half of that in the 0.1- year sample. Micropores smaller than 0.6 nm in wood with a few decades or more of elapsed time increased in number after rewetting and drying. Consequently, microstructures of wood with longer time elapsed in the environment were considered to be more stable, because of longer-term thermal motion and possibly more repeated moisture adsorption and desorption and/or temperature variation in the environment.     

Testing and evaluation of natural durability of wood in above ground conditions in Europe – an overview

Natural durability of wood is determined by the European standard EN 252 for specimens in ground contact and EN 113 for basidiomycetes in the laboratory, but no test exists for above ground conditions. For above ground conditions, the European prestandard ENV 12037 and EN 330 are used to determine the durability of treated wood. The most important factors for fungal establishment on the surface and within wood are the moisture content, the surrounding temperature, and the relative humidity. Strength tests are the most sensitive for decay detection, but neither strength tests nor identification of fungi responsible for the decay are included in the standards of above ground durability in field tests. To detect decay, visual examination, pick or splinter tests, and mass loss determination are used. Identifying fungi with traditional methods, e.g., growth on solid medium, is time consuming and complicated. Molecular methods like polymerase chain reaction and sequencing do not require mycological skill for identification to species level, and furthermore the methods do not depend on the subjective judgement like most traditional methods, but are based on the objective information of the target organism (e.g., nucleotide sequences). The next generation of standard field tests will probably consider the drawbacks of standard tests today and be rapid and include both quality tests like molecular identification and nondestructive quantitative tests, e.g., acoustic tests. Laboratory tests can be improved by using fungi identified from field trials and by combining different fungi in the same test and thus simulate degradation in practice.     

时域核磁共振技术在木材科学研究领域的应用

时域核磁共振技术（TD-NMR）作为一种先进的表征手段,能快速、精准测量木材中自由水和吸着水的动态变化,也可以基于水分信息表征木材孔隙分布,因此已被广泛应用于木材科学研究领域。文中归纳了时域核磁共振技术用于测量木材含水率、水分性质、水分分布及木材孔隙分布的方法,并对主要研究结果进行综述,以期为相关领域的研究和应用提供理论参考。     

The effects of drying on the structure and permeability of the wood of Abies grandis

Summary The effects of air-drying and solvent-drying on the sapwood of Abies grandis have been investigated by a new method for the determination of the size and number of conducting tracheid lumina and pit membrane pores which involves the measurement of gaseous permeability at various mean pressures. Both earlywood and latewood tracheids (83% of the total) were found to be conducting in solvent-dried wood, but in air-dried wood only latewood tracheids (32% of the total) were conducting. In solvent-dried wood there were on average 27,000 pit membrane pores per conducting tracheid compared with only 600 in air-dried wood. In both, the average pit membrane pore radius was about 0.1 m.Liquid permeabilities have been predicted from the calculated radii and numbers. The liquid permeability of solvent-dried wood was 31 times greater than that of air-dried wood in which the lumina were responsible for 13% of the total resistance to flow. The lumina were responsible for 39% of the resistance in solvent-dried wood and it is suggested that in first-formed earlywood the lumina may cause more than half the total resistance.A new method is described for the cleaning of direct carbon replicas of wood. In this the cellulose is removed by cellulase instead of sulphuric acid, and no wax backing is required. This provides much cleaner replicas. Electron micrographs have been obtained of both earlywood and latewood dried by the two methods.The authors wish to thank Mr. A. R. Sayers for preparing the computer programme used in this work, Dr. R. Ph. C. Johnson for his help and advice regarding the electron microscopy and Professors Matthews and Weatherley for their advice and encouragement.     

木材海绵研究进展

天然木材制备的木材海绵可替代硅胶海绵、聚氨酯和三聚氰胺等合成高分子基海绵,作为高效吸油剂用于污水净化,并衍生出一系列运用。在去除木质素和半纤维素后,天然木质材料保留了原生的精巧三维分级孔隙结构,从木材直接转化为生物基纤维素骨架,具备高孔隙率、比表面积大、优异机械性能等特性的同时,还保留了木材生物相容性等特点。对木质纤维素骨架进一步改性后得到的木材海绵,在油水分离、能源存储、传感器、穿戴设备等领域具备一定的发展潜力。文中综述目前制备木材海绵的有效方法,包括精巧分级孔隙率的木质纤维素骨架制备和基于该木质纤维素骨架的各类功能性材料开发探索;针对木材海绵的高效制备和功能化,从基础物质、基本性能与工艺流程角度梳理近5年的相关工作,以启发该类先进材料的创制思路;同时,探讨木材海绵功能的先进性,并对其应用前景进行展望。