灰色系统理论在防护林体系效益预测中的应用

本文结合兴胜村防护林体系多年实际调查资料，利用灰色系统理论对体系的立木蓄积年增长率和立木蓄积量分别进行了建模和预测，并根据出材率和木材价格估算，得到该体系木材产值的预测区间和预测值，为防护林体系效益估算和预测提供了新的方法。     

灰色理论在预测我省森工系统90年代产值中的应用

本文简介了灰色预测的基础模型ＧＭ（１，１）模型的建模思想。对我省森林工业总产值、森工木材采运总产值、森工木材加工总产值作了１９９３－２０００年产值预测，并对预测结果进行分析讨论提出了几个控制模型。     

大兴安岭林区森林蓄积量预测模型的研究

将灰色系统理论应用于大兴安岭林区森林蓄积量的预测,建立了灰色系统模型,在建立不同数量原始数据的模型基础之上,比较其模型精度,优选出最佳模型,用于森林蓄积量模拟与预测。模拟值与实际值的误差均符合精度要求。将模型用于森林蓄积量预测,结果表明预测精度达到了99．54％。本研究成果可作为大兴安岭林区森林经营管理的理论参考。     

韩国的森林和林业

韩国的森林和林业赵劼截至１９８６年，韩国的林地面积为６５３．１万公顷，占国土面积的６６％，其中针叶林占４６％，阔叶林和混交林占２７％。木材总蓄积量为１．７９３亿立方米，每公顷平均蓄积量２７立方米，针叶林蓄积量占全部蓄积的４５％，混交林占２７％，阔叶林...     

应用灰色系统理论预测城峰镇"十五"期间有林地面积与森林蓄积量变化的研究

以永泰县城峰镇1986～1999年历年有林地面积、森林蓄积量数据为基础,应用灰色系统理论与方法,建立灰色预测GM(1,1)模型,以城峰镇“十五”期间的有林地面积与森林蓄积量进行预测。经检验,有林地面积GM(1,1)模型(1986～1999年)预测值的平均误差2.23％,森林蓄积量GM(1,1)模型(1986～1999年)预测值的平均误差1.16％,预测精度较高,可以对“十五”期间城峰镇有林地面积与森林蓄积量进行预测。     

福建省森林蓄积量变化趋势灰色预测

应用灰色系统理论与方法,以1978-2013年全省森林资源连续清查的森林蓄积量为时间数据序列,分不同时段建立GM(1,1)拓扑模型,从中选出一个相对误差较小、精度等级较高的模型,对未来时间内(2018年、2023年)的全省森林蓄积量进行灰色预测,并采用内插法计算出2020年全省森林蓄积量,旨在为确定2020年福建省森林蓄积量规划目标提供参考。     

松溪渭田镇森林资源发展趋势的灰色预测

应用灰色系统与方法,以松溪县渭田镇森林资源调查统计数据为基础,建立灰色预测GM（1,1）模型,对松溪县渭田镇森林资源主要指标（森林覆盖率、有林地面积、活立木蓄积量、用材林蓄积量、近成过熟林蓄积量）的发展趋势进行预测。预测结果经检验,预测精度好,可信度高,可为福建省松溪县渭田镇森林资源研究提供切实可靠的分析工具。     

基于改进灰色马尔科夫模型的木材需求量预测

以木材需求量2005―2013年数据为原始数据,建立了传统灰色、无偏灰色和滑动无偏灰色模型,并分别以3种模型预测2014―2015年木材需求量。通过检验模型的拟合效果和对比预测的相对误差,选取预测效果最优的滑动无偏灰色模型为待修正模型。以滑动无偏灰色预测数据的相对误差分布为状态划分依据,考虑实际情况对一般马尔科夫修正方法进行优化,以优化的修正方法对预测数据进行修正。最终结果表明:当进行改进马尔科夫修正时,滑动无偏灰色预测模型的平均相对误差从6.44%降至1.49%,预测误差减少4.95%,预测精度明显提升,能够为我国未来木材需求量的准确预测提供可靠的理论依据。     

武义县林业资源的灰色系统动态预测

运用灰色系统理论，建立武义县林业资源的灰色系统动态预测模型，对武义县林业用地面积、总蓄积量的发展趋势分别作出预测，旨在为武义县林业将来的经营决策提供科学依据。     

宁德市森林资源变化的灰色预测

应用灰色系统理论与方法，以宁德市1997-2002年资源建档数据为基础，建立灰色预测GM(1，1)模型，对宁德市森林资源主要指标(1、森林覆盖率；2、有林地面积：3、活立木总蓄积量)的变化进行预测，由于资源建档数据具有连续性、可比性等特征，经检验，预测值的精度较高，可以对宁德市未来森林资源数据进行预测。     

鼓式削片机切削参数模拟研究

为解决实际生产过程中削片机切削能量损耗大、功率不匹配和生产效率较低等问题,基于断裂力学理论和Ⅰ、Ⅱ、Ⅲ型混合模态断裂准则,以及年轮对木材断裂的影响,将刀具旋转切削的动力学问题转为对木料的断裂分析。通过对木料在切削过程中的受力分析,确定裂纹扩展模型,构建了力学模型,推导并研究了切削力与各切削参数之间的关系;借助MATLAB软件建模分析切削角、木料半径和切削厚度与切削力的关系,得到切削角θ=π/4,裂纹极角φ=2π/5时,切削能耗较优。     

Knife slicing of wood across the grain

Summary This paper investigates a method for slicing thick pieces of wood across the grain using a sharp steel knife, and it demonstrates the effectiveness of the knife slicing process at an experimental level. In order to highlight the key parameters facilitating or hindering the thick slicing process, several factors affecting the cutting forces and the cut surface quality have been studied; the blade geometry, the effect of friction, the cutting speed, the boundary load constraints and the wood moisture content. The results indicate that a large proportion of the cutting force may be related to the wedging action of the blade in the wood. Therefore, significant reductions in the cutting energy can be achieved by optimising the blade shape. A simple homogeneous strain model has been developed which quantifies the cutting forces in terms of the blade angle and the blade surface friction. The results from this theoretical model are compared with the experimental findings and discussed in relation to methods for improving the cutting technique.This work was funded by the Foundation for Research Science and Technology. This support is gratefully acknowledged     

STUDY AND ANALYSIS OF CUTTING FORCES ON OBLIQUE CUTTING OF WOOD

Oblique cutting of wood is an important form of cutting wood.With the developingof woodworking industry,it is widely used in wood machinary processing such as planing,milling,sawing,drilling and so on.This paper takes oblique planing and helix milling of wood as examples.The influences of bevel angle and other factors on the cutting force have been shown.The changingrules of cutting forces have been summarized.On the basis of it,we especially carried out theoreticalanalysis on the changing rules of cutting forces and discussed the influence of the changing rules onpractice.     

Wood structure of <Emphasis Type="Italic">Populus alba</Emphasis> formed in a shortened annual cycle system

Wood formation of trees that grow along the seasons has an annual rhythm. Due to this rhythm, physiological research on the mechanism of wood formation has been difficult to conduct in a typical experimental room. In the present study, we observed the wood tissue formation in a shortened annual cycle system, which was developed for poplar trees grown in a growth chamber with dormant and non-dormant cycles. Poplar trees were grown in this system by repeating the cycle three times. The resulting wood tissue consisted of three growth rings and very similar structures were observed around the ring boundary of the wood in a field-grown stem. This result suggests that the shortened annual cycle system can be adopted as a model for physiological, cell biological and molecular research of wood and annual ring formation.     

A review on wood machining: characterization,optimization, and monitoring of the sawing process

ABSTRACT

Sawing is the most common machining process and is present in both primary and secondary wood transformation sectors. The objective of this paper is to review how it is affected by different factors. The current challenges associated with various machining factors, process monitoring, and sensor selection were identified and explained. Consequently, four research challenges and technological gaps were outlined. (1) Contradictory results have been reported due to different cutting processes, wood species, measurement methods, and cutting speed range studied in literature, so special consideration needs to be taken when comparing results with those available in the literature. (2) Laboratory test conditions cannot yet fully represent the extreme cutting conditions in sawmills. More emphasis should be placed on those harsh industrial cutting conditions. (3) Research on wood cutting lacks multi-objective optimization approach, which suggests that sawdust generation should be simultaneously analysed with surface quality and power consumption. (4) Compared with metal cutting, little research has been conducted on wood sawing monitoring using an artificial intelligence approach, which should be prioritized in designing adaptive control systems. Combining intelligent monitoring and multi-objective optimization approaches should pave the way for controlling the sawing process so higher surface quality and cost efficient machining is achieved.     

Modelling the distribution of wood properties along the stems of Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) Karst.) as affected by silvicultural management

In this work, empirical ring-based models were developed to predict the distribution of early wood percentage, wood density and fibre length along the stems of Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) Karst.) as affected by silvicultural management. The performance of the ring-based models was also compared for Scots pine and Norway spruce with corresponding disc-based (cross-sectional) models. Moreover, both models were integrated with example simulations by a process-based growth and yield model to analyze how management, such as thinning, affects the growth and wood properties of Scots pine trees over a rotation as an average for the tree stem, but also along the stem.The ring-based models built for annual early wood percentage (explained by ring width), air dry wood density (explained by early wood percentage and cambial age) and fibre length (explained by radial growth percentage and cambial age) predicted reasonably well the wood properties both at an intra-ring level, but also at a cross-sectional level. These predictions were also reasonably well in line with corresponding cross-sectional predictions by the disc-based models (which predicted the properties based on the number of annual rings and diameter at breast height and/or the cross-section being considered and temperature sum). The example simulations also demonstrated that both models predicted slightly lower wood density for dominant trees compared to dominated ones grown in thinned and unthinned Scots pine stands over a rotation. Unlike the disc-based model, the ring-based model predicted, on average, higher early wood percentage in dominant trees than in dominated ones. However, fibre length was not significantly affected when the averages of the whole stems were predicted, and this held true for both ring- and disc-based models.In summary, the incorporation of empirical ring-based wood property models into a process-based growth and yield model, offers a means to study in detail how environmental conditions, forest structure and management affect the quantity and properties of stem wood produced over a rotation. The disc-based wood property models used in this work are based on data with large geographical and genetic variation, and therefore may turn out to be more applicable for predicting future wood and fibre resources at a regional and national level. This kind of integrated use of wood property models with a process-based growth and yield model could help us to evaluate the forest resources under current and changing climate.     

基本型动力链锯锯木参数的研究

本文在试验的基础上,考查链锯锯木参数中的切削速度,同名齿进给量,锯口长度和进锯角变化对锯切指标的影响,得出了上述参数影响锯切指标(切削力、锯木功率。锯木生产率、单位锯切功)的方差分析结果,进一步采用逐步回归分析方法,得到含有主要影响因素的各锯切指标的回归公式,对链锯设计与计算有着重要意义。     

数控微米刨切试验台的设计与试验

为解决传统热磨法加工微米薄木片及木纤维中高能耗、工序复杂、加工成本高的缺点,现改变加工方法,采用顺纹纵向刨切木材的方式,研发了数控微米刨切试验台。试验台主要由机架、纵向进给机构总成、工件夹具、控制面板、刨切机构总成、升降机构总成和限位机构组成,可对宽度为50 mm,长度为300～600 mm,高度为20～90 mm的木材工件进行纵向进给、切削量进给和刨切作业。笔者对试验台整机以及各机构进行设计,并通过ANSYSY对刀具进行强度校核。通过试验,确定刨切机构切削角δ取45°,刀刃伸出量h取0.05 mm,刀门宽度d取0.2 mm,刨得的木片平均厚度为18.7μm,最薄为15μm。最后通过显微镜观察发现经过刨切后的刀刃部分出现磨损,可通过表面改性提高刀具的耐磨性。     

白夹竹丰产技术研究初报

对白夹竹林进行丰产技术研究结果证明,施肥、抚育、间伐等措施确能提高白夹竹林分的产量和质量。试验进一步揭示施肥能提高白夹竹林产量和质量的关键性技术是施肥时间和施肥三要素(N、P、K)配方的比例及用量。同时指出,间伐强度要依立竹胸径、叶面积指数而定,并要保证母竹林分布的均匀。本试验为白夹竹林实行科学经营提供依据。     

山杨嫩枝扦插新技术试验初报

采用两种不同插穗进行山杨优树嫩枝扦插对比试验，结果表明：取自根蘖条的幼化型插穗同自树冠的插穗相比，在相同条件下，生根率，新根最大长度，扦插苗成活率均有显著提高，进一步用木段促萌，生产幼化型插穗的方法也取得了成功，从而总结了出一套较为简便经济的山杨优树无性繁殖技术。