世界原木定心技术现状及发展趋势

原木定心技术在木材加工生产中广泛应用。精确定心,对提高木材利用率及经济效益是十分重要的。在分析现有定心技术的基础上,综合世界森林资源短缺及科学技术进步情况,提出原木定心技术向采用计算机扫描控制、提高精度、效益和效率方面发展是必然趋势。     

Simulated grading of logs with an x‐ray log scanner‐grading accuracy compared with manual grading

Today sawmills have started to use automatic methods for log grading. The methods used are either optical or gamma‐ray scanners. However, the signals from these scanners are too coarse for accurate log grading and for good control of the sawing process at the single log level. The objective of the present study was to determine the grading accuracy of a log‐scanner with two industrial X‐ray sources. The grading accuracy was compared with the accuracy of manual grading. The results showed that the manual grading of logs and boards is difficult. The accuracy of manual grading was low and the automatic grading systems were more reliable than manual ones. Possibilities for improving the automatic grading systems are discussed.     

基于原木断层图像的三维重构技术研究

利用OpenGL和VC＋＋平台进行原木断层图像三维重构的研究。首先对断层图像进行轮廓形状插值,然后对轮廓线进行连续性处理,最后使用双三次B样条插值曲面来实现轮廓线的三维重构。实验结果表明,本文提供的方法可以很好的将一组原木腐朽断层图像还原为三维立体图,为原木缺陷检测、立木健康评价等方面提供应用理论基础和科学依据。     

THE APPLICATION OF SPLINE FUNCTION IN THE GEOMETRIC REPRODUCTION OF LOG SHAPE

FORWARDInwood-processingproduction,theeffectivewaytoraiselogutilizationandobtainthebesteconomicalbenefitistohaveaoptimumandreasonablesawcut-tingscheme.Thedeterminationoftheoptimumsawcuttingschemeshou1dbemadein1ightoflognaturalconditions,suchasitsgeometricsize,theoutlinesofthecrosssectionsatitsoppositeends,itsgeometricshape,andalsobasedonsawingwoodspecificationsacquiredandontheprincip1eofoptimumloguti1izationandthebesteconomicalbenefit.Inrecentyears,theresearchpapersconcerningthemethodsofgeom…     

计算机及图像识别技术在原木检尺中的应用研究

利用计算机图像识别及条形码技术,以人机交互方式实现原木自动检尺。通过对检尺图片采集、条码数据采集、计算机检尺、图表打印、系统功能等的生产实验,总结分析了各项试验结论并就测试数据计算了计算机原木检尺的各项数据精度,为进一步改进完善研究成果提供了依据。     

Identification of selected internal wood characteristics in computed tomography images of black spruce: a comparison study

The feasibility of identifying internal wood characteristics in computed tomography (CT) images of black spruce was investigated using two promising classifiers: the maximum likelihood classifier (MLC) and the back propagation (BP) artificial neural network (ANN) classifier. Nine image features including one spectral feature (gray level values), a distance feature, and seven textural features were employed to develop the classifiers. The selected internal wood characteristics to be identified included heartwood, sapwood, bark, and knots. Twenty cross-sectional CT images of a black spruce log were randomly selected to develop the two classifiers. The results suggest that both classifiers produced high classification accuracy. Compared with the MLC classifier (80.9% overall accuracy), the BP ANN classifier had better classification performance (97.6% overall accuracy). Moreover, statistical analysis reveals that the heartwood of the black spruce log used in this study is the easiest to identify by either classifier compared with the other three log features. The results also suggest that the separability of one wood characteristic from the other wood characteristics in black spruce CT images is mainly related to moisture content.     

无卡轴旋切机变速进给模型的多项式拟合

为了解决无卡轴旋切机圆木旋切过程中进给电机转速与刀刃所处水平位置的数学模型计算耗时的问题,本文采用Mathematica工具对转速函数进行多项式拟合,得出简单且便于单片机运算的拟合函数.同时运用Mathematica比较分析了原函数和各次拟合函数间的转速差及加工后的单板厚度误差.     

辽宁东部地区主要树种组林分平均胸径生长率模型的研究

该文采用超总体理论编制辽宁省东部地区主要树种组林分平均胸径生长率通用模型，以2005年森林资源二类调查资料为原始数据，涵盖辽宁东部7个市31个县（市、区）8个树种（组）在不同地理位置和不同立地条件的生长水平。建立4种模拟方程，通过拟合与优化及结果精度的检验选出了各树种组的平均胸径生长率模型。     

Comparing Grade Classification Criteria for Automatic Sorting of Norway Spruce Saw Logs

Grades of centre and side boards from 277 Norway spruce logs were combined to form binary response variables, here denoted as sorting criteria. Four different grading systems were tested. The log geometry variables unevenness, butt taper and top taper were used in logistic regression models. The classification accuracy ranged from 58 to 83%. The accuracy was higher for visual stress grade criteria than for more complex criteria such as the Nordic timber grading rules. The number of tested criteria and thus possible comparisons limited the ability to establish significant differences. The low associations between board grades within logs and between graders, highlight key issues when developing and improving automatic log sorting systems.     

原木材积表计算器程序编制

利用casiofx-3900pv计算器编制原木材积表程序，该法不需查表或手工计算，只需给计算器输入检尽径、检尺长，即可求算出相对应的材积值，方法简便、快速、并能提高工效及精度。     

Modelling of knots in logs

A geometrical model was derived to describe knots in logs and on the surface of lumber beams sawn from those logs. Each knot is defined by 7 parameters related to the shape and position in the stem. A computer simulation program was written to study knot shapes on a variety of observation planes.An initial investigation on the shape of knots in Scots pine logs and lumber beams suggests that the model is sufficiently accurate to describe knottiness in this species. Potential applications of this model include automated lumber grading, computerized log reconstitution and yield optimization studies.This research was carried out when the author was a Visiting Scientist at the Technical Research Centre of Finland (VTT), Forest Products Laboratory, P.O. Box 207, SF-02151 Espoo, Finland. Technical assistance of U. Saarelainen, A. Usenius and C. O. Sommardahl from VTT is gratefully acknowledged. This work was partially supported by Forestry Canada and the Natural Sciences and Engineering Research Council of Canada     

Spatial correlation of tensile perpendicular to grain properties in Norway spruce timber

Tensile strength perpendicular to grain constitutes one of the most vulnerable properties of timber. Due to versatile influencing parameters this property exhibits a high amount of uncertainty. Thus, progress in modeling, in particular by considering stochastics, is seen as worthwhile. This increases the reliability estimates of timber constructions but also their economic efficiency. Test data of tensile properties determined on consecutive board segments of Norway spruce are analyzed. The data consists of four subgroups, classified in regard to segment length and radial position within the log. The correlation in longitudinal direction of perpendicular to grain tensile strength and elastic modulus as well as of density is examined. This is done depending on the radial position of structural timber within the log. A second-order hierarchical model together with equicorrelation is used. The results outline the applicability of the model and allow the quantification of equicorrelation coefficients of all three properties. The outcome provides a valuable and necessary input for state-of-the-art mechanics-stochastic modeling of the resistance perpendicular to grain tensile strength and elastic modulus of unjointed and jointed structural timber, but in particular of products available in large dimensions, like glued and cross-laminated timber. Additionally, the spatial correlation of density is discussed which is seen as worthwhile for the estimation of group action of fasteners. The necessity to differentiate between the variability within and between segments of structural timber is clearly demonstrated.     

A dynamic simulation study of the impacts of enhanced UV-B radiation on winter wheat photosynthetic production and dry matter accumulation

By using the system-dynamic software package STELLA, a simulative study was conducted on the photosynthetic productivity and change of the accumulated dry matter of wheat population, related to enhanced UV-B radiation that influences photosynthesis. The effects of daily temperature and crop physiological age on the photosynthesis rate were considered comprehensively. Statistical analysis was undertaken to assess the fitness between simulations and observations of accumulated dry matter by means of root-mean-square error and relative error. Results show that there is no significant difference between simulations and observations, indicating that the STELLA software is effective in imitating the growth. This software provides a new approach in establishing a simulative model for crop growth under the conditions of various climate and environment.     

基于Flexsim软件的鼓风机叶轮加工系统仿真

加工系统仿真是利用加工系统模型在仿真环境和条件下,对加工系统进行研究分析和实验.其目的是找出瓶颈所在,并通过仿真实验研究系统优化目标下的一些系统参数和运作策略的优化设置,作为决策分析的依据.应用Flexsim 3.0 Demo离散事件仿真软件程序,对工业企业中真实的加工系统建立仿真模型,从而分析加工系统中存在的问题,找出解决这些问题的办法和措施.     

永安巨桉一元材种出材率表编制研究

在永安市巨桉(Eucalyptus Garndis)林分选择并设置10个标准地,分别进行林分因子调查,以4m段材长分径阶进行样木伐倒造材,应用区分求积式进行材积计算,以实际造材各材种出材率为基础拟合一元材积比方程,根据相关系选择较优的一元材积比方程进行理论造材并编制巨桉林分一元材种出材率表,并进行精度检验,表明精度可达90%以上,可为桉树生产提供一定的参考。     

Predicting spiral grain by computed tomography of Norway spruce

Spiral grain is a feature of wood that affects the shape of the sawn timber. Boards sawn from logs with a large spiral grain have a tendency to twist when the moisture content changes. The aim of this study was to investigate the possibility of predicting spiral grain based on variables that should be measurable with an X-ray LogScanner. The study was based on 49 Norway spruce (Picea abies) logs from three stands in Sweden. The logs were scanned with a computed tomography (CT) scanner every 10mm along the log. Concentric surfaces at various distances from the pith were then reconstructed from the stack of CT images. The spiral grain angle was measured in these concentric surface images, and a statistical model for predicting spiral grain was calibrated using partial least squares (PLS) regression. The PLS model predicts the spiral grain of a log at a distance 50mm from the pith based on different variables that should be measurable with an industrial X-ray LogScanner. The result was a PLS model withR ²=0.52 for the training set andR ²=0.37 for the test set. We concluded that it should be possible to predict the spiral grain of a log based on variables measured by an industrial X-ray LogScanner. The most important variables for predicting spiral grain were measures of sapwood content, variation in the ratio between the heartwood and log areas, and the standard deviation for the mean log density in 10mm thick cross slices along the log. The accuracy when sorting the logs into two groups with spiral grain of 2.0° and of <2.0°, respectively, was 84% of the correctly sorted logs.     

Evaluation of pedotransfer functions for estimating soil hydraulic properties of prevalent soils in a catchment of the Bavarian Alps

In this study, two types of pedotransfer functions (PTFs) were evaluated for their accuracy and applicability to a broad range of Alpine soils in the Halbammer area in southern Bavaria (Germany). The first model is ROSETTA, which is based on neural network analyses. It implements five hierarchical PTFs using limited to more extend input data. The second model is SOILPROP that is based on physical methods and predicts the soil hydraulic properties from particle size distribution and bulk density. The PTF were evaluated by comparing predicted with measured water retention values. The accuracy was quantified by direct statistical evaluation with the correlation coefficient (R), the mean error (ME) and the root mean square difference (RMSD). Additionally, a process based functional validation was performed by simulating the water flow using the measured and predicted soil hydraulic data. The RMSD values from ROSETTA models ranged from 0.068 to 0.202 cm³/cm³ for the water retention and from 0.450 to 0.579 log K_s (cm/day) concerning the hydraulic conductivity (K _s). The ME indicated underestimated water contents at high suctions and for soils with high organic content. The functional evaluation was the better as the more input data were used in the hierarchical PTFs. The RMSD of SOILPROP was 0.073 cm³/cm³ for water contents and 0.718 log K_s (cm/day) for the hydraulic conductivity. The water contents in the middle suction range were underestimated in sandy soils and overestimated in soils with low bulk density. The functional evaluation showed improved model accuracy when the predicted saturated conductivity was adjusted to more realistic values from literature showing its sensitiveness towards water flow modelling.     

原木输送机拆除原因分析与对策

原木输送机作为一种选材机械，多年来在我国林区贮木场选材作业中发挥了巨大作用。由于资源变化及经济技术等方面的原因，相当一部分贮木场拆除原木输送机，采用其他的选材工艺与设备，究竟什么是主要原因呢？本文对此进行了较为深入的分析研究。     

传感器数量对应力波检测原木内部缺陷精度的影响

木材无损检测技术是高效利用木材的方法之一.该文阐述了应力波法检测木材缺陷的原理,分析了传感器数量对图像的拟合度和误差率两个指标的影响.结果表明,当原木直径在20～40cm范围内时,若需对原木缺陷进行精确测量,要求图像拟合度接近90%和误差率在0.1左右时,至少需12个传感器才能满足要求;当不需要对原木缺陷进行精确测量,只需确定缺陷的大致位置时,宜选用10个传感器进行测量;当仅仅需要判断原木是否存在缺陷时,选用6个传感器就能满足要求.图3表4参8.     

大花蕙兰(Cymbidium hybridum )试管苗基部切块诱导类原球茎研究

以大花蕙兰试管苗基部切块为外植体,以MS培养基为基本培养基,培养诱导类原球茎(PLB),研究不同激素配比以及外植体来源基因型对PLB诱导的影响.低水平的2,4-D和较高水平的6-BA对于试管苗基部切块诱导PLB具有显著的促进作用.当2,4-D浓度高于0.60 mg·L-1时,PLB诱导受到显著抑制.不同基因型有不同的最佳激素组合.NAA对特定基因型诱导PLB有效.以试管苗基部切块组织培养方式诱导大花蕙兰PLB是可行的,为转基因研究提供了植株再生技术基础.