Responses of Young Norway Spruce (Picea abies) to Winter Browsing by Roe Deer (Capreolus capreolus): Effects on Height Growth and Stem Morphology

The effects of natural and simulated winter browsing by roe deer on mortality, growth and defects in tree form among young recently planted Norway spruces were studied in two field studies and one simulation (clipping) experiment. No effect of browsing or clipping on mortality was observed. However, height growth was reduced by browsing and clipping, and the reduction increased with increases in the number of years in which they were browsed or clipped. Browsing or clipping in three successive years reduced height growth by the equivalent of about 1 yr. Spruces frequently became multi-trunked and/or developed multiple leaders as long as browsing and clipping lasted. However, when the browsing or clipping ceased, almost all spruces became single-trunked again. A more persistent effect was that many of the multiple trunks developed into large, abnormal branches or "spike-knots". The characteristics of the spike-knots resulting from browsing and clipping were very similar to those caused by other types of damage. The results indicate that roe deer browsing on spruce is less harmful than many Swedish foresters have feared.     

Application of modal-based damage-detection method to locate and evaluate damage in timber beams

Modal-based damage-detection algorithms were used to identify the location of defects commonly found in timber and to estimate their severities. In this study, the authors propose modifications to an existing damage-detection algorithm for locating and evaluating damage by comparing the modal strain energy before and after damage using the first two flexural modes of vibration. Experimental verification was performed on pin-pin supported timber beams by employing the algorithms with extracted modal parameters using experimental modal analysis. Single and multiple cases of damage used to simulate pocket(s) of rot with various severities were inflicted by removing sections of timber beam specimens. The proposed damage indicator, computed from the first two flexural modes, was capable of detecting all damage locations. It was also able to estimate, with reasonable accuracy, the severity of damage in term of loss of sectional moment of inertia. The modified damage index method is generally reliable in detecting the location and estimating the severity of simulated defects in timber beams.     

MICROCOMPUTER PROCESSING THE PHOTOGRAPH OF TIMBER WITH HOLE KNOTS

THRESHoLDWhenthetimberswiththeho1eknotsarepassedthesystemofX-raynon-de-structiveinvestigation,thesimulatednu-meralsfigureoftheholeknotsappearinthemonitor.Thesimulatednumeralsfigureisshownintablel.Meanwhilethehistogramofthisfigurearedoublepeakcertainly.Inordertoidentifytheedgeoftheholeknotswithnakedeyeandcarryoutautomatictreatment,Wetakethebinaryva1uetreatmentforthefigure'Thechoos-ingthresholdisaveryimportantpartinthebinaryvaluetreatment.Howtochooseasuitablethreshold?Weshouldpaymuchattenti…     

超声波与应力波在木材内部缺陷检测中的对比研究

采用超声波和应力波分别对木材试件进行了检测,并运用SPSS软件对检测结果进行分析,结果表明：木材密度、孔洞大小及数量对两种波传播参数及动态弹性模量都有不同程度的影响。通过两种波的对比研究,得知二者对木材内部缺陷检测的灵敏度和准确度存在差异。因此在进行木材内部缺陷检测时,应结合实际情况,采用适当的检测方法,从而提高对木材缺陷盼分辨能力。     

非破坏性木材内部缺陷检测--木材CT扫描研究动态

对断层扫描技术(CT)在木材工业中应用的可行性,以及在木材工业中实际应用之前需要解决的问题进行了探讨.针对木材CT图象的各种处理方法,以及各国目前在该领域的研究动态进行了回顾.将CT技术引进木材工业,将使锯材和单板生产的价值最优化成为可能.     

利用振动法检测胶合板的剪切弹性模量

首次提出用表面波传播法对胶合板的剪切弹性模量进行无损检测，并与利用弯曲振动试验测得的动态剪切弹性模量进行比较分析，结果表明，两种方法测得剪切弹性模量值不同，有的甚至相差甚大，理论计算证明，表面波传播法检测胶合板剪切弹性模量更合适，可解决纤维倾斜角45度方向上胶合板动态剪切弹性模量测定的难题。     

Modeling timber mill procurement influence effects on interstate sawlog exportation

Over the last three decades the exportation rate of raw sawlogs from Illinois to neighboring states for processing has nearly doubled. While the exportation of sawlogs has adverse impacts on the Illinois wood products manufacturing sector and local forest landowners, little research has been conducted to understand how the spatial arrangement of timber mills affects sawlog exportation. This research models, in a spatial environment, timber mill procurement influence within southern Illinois and the surrounding region in an attempt to understand how the location of mills is a partial explanation of the increase in sawlog exportation. Assuming equal market power, timber mills within the study area were found to be arranged in a manner that results in low competition for sawlogs within Illinois and high competition in neighboring states. Spatial models incorporating differential market power based on mill size characteristics suggest that Illinois experiences little procurement pressure from high production mills operating within the State but is under procurement pressure from high production timber mills operating in neighboring states.     

利用振动法检测胶合板的抗弯弹性模量

通过弯曲振动试验、纵波传播试验及纵波共振试验对胶合板的抗弯弹性模量进行无损检测，并分析了三种试验方法测定结果之间的关系。结果表明：虽然不同方法测得的胶合板弹性模量值不同，但其间存在一定的内在联系。     

空心胶合木梁柱式结构抗侧力性能研究

为研究空心胶合木梁柱式结构体系抗侧力性能,对纯框架及框架-人字撑两种单跨结构试件进行了单调及低周反复加载试验,考察了结构破坏模式、耗能能力、刚度等抗震性能。结果表明:纯框架与框架-人字撑结构均具有一定抗侧力性能,但纯框架结构承载能力较弱,不建议单独用于工程实践;框架-人字撑结构具较大抗侧刚度及承载力,分别为纯框架的6.3倍及2.68倍,但其延性仅为纯框架的67%。两种结构失效前强度退化小于30%,具足够剩余承载力。     

国际木材价格波动对我国家具生产企业的影响

家具生产企业是我国制造业的重要组成部分。随着我国家具进出口贸易的不断发展,国际木材价格波动对我国家具生产企业的发展造成了严峻挑战。基于国际木材价格波动现状,分析国外木材原料的价格波动特征对国内木材原料市场异常价格波动带来的影响,以规避潜在的市场风险,促进国内家具企业的发展,在此基础上,有针对性地提出对策建议。     

林分材积计算的标准木方法的误差分析及校正

在指出了森林林分材积计算的标准本方法偏低估计实际材积的系统误差的基础上,提出了两种校正方案。校正系数可以从在林分内选择标准木的采样样本的数据中方便地算出。模拟举例计算说明两种校正方案基本消除了原公式的系统偏差。校正后的公式为：其中：为林分材积估计值;ＶＢＫ和ＡＢＫ分别是第Ｋ株标准木的测量材积和胸高断面面积;ＡＴ是林分的总胸高断面面积：ｈＢ,和ｄＢ是抽样算得的具有平均胸高断面面积的树的高度和胸径;ｄＷ是抽样算得的以胸高断面面积为权重的加权平均胸径;ｂ是树高曲线在ｄ＝ｄＢ处的斜率。校正的第２方案具有与上式完全相同的形式,只是标准木的是具有平均胸径的树木。     

几种防腐剂处理尾叶桉,湿地松和马尾松木材的室内促进试验

对马尾松、湿地松和尾叶桉３种木材用Ａ、Ｂ、Ｃ３种防腐剂处理,通过室内促进试验测得各种防腐剂使用量的临界值,结果表明,３种木材的天然耐腐性均属不耐腐或易腐烂等级,经防腐剂处理后,木材的防腐效果较好,且Ａ防腐剂较Ｂ、Ｃ为好。试验结果可为实际处理生产工艺的制定及预测防腐剂的处理效果提供参考。     

贵州一元立木材积表误差分析与修正探讨

论述贵州现用一元立木材积表存在的问题和误差来源，对原材积式与新材积式进行误差对比及适用性检验。提出立木材积式的选择、误差修正的方法与应用和重编材积表的紧迫性。     

贮木场原木结存系数探讨

\"结存系数\"是贮木场设计的主要技术指标.本文拟就兴隆林业局的具体实践对现代贮木场的适宜结存系数做以探讨.     

杉木生长,材性兼优种源选择的研究

经对杉木中心产区优良种源的中间试验研究表明,种源间生长与木材基本密度性状有一定差异,根据对１２年木材基本密度性状和９年材积生长性状的测定结果,初步选出广西那坡,贵州锦屏,贵州榕江等生长,材性兼优的种源。其木材基本密度与广西融水优良种源相近,材积生长比融水种源增加４７．０％￣８３．６％,遗传增益达１３．４１％￣２３．８６％。     

“一带一路”背景下木材加工企业的跨境发展策略

随着一带一路倡议的提出,我国越来越多的企业加入到跨境发展当中,对全球经济和社会发展产生了深刻影响。由于我国木材加工企业跨境发展的时间较短,在很多方面缺少足够的经验,对风险的实际应对能力有待提高。针对当前我国木材加工企业跨境发展的现状和存在的问题进行了分析,进而针对性地提出了相关策略,这对于提升我国木材加工企业的整体跨境发展水平和跨境竞争力等具有重要意义。