桉树优良无性系制浆造纸性能与适应性的研究

对福建漳州岩溪、天马和南靖3个试验点桉树品系的抗风抗冻、纤维材生长性状、木材纤维形态和化学组成成分等性能的测定与分析,经多性状综合评判、交互效应与变异分析,从中选择出具有抗逆性强、纸浆性能好、较高生长量、生物量和纤维产量,适合闽南山地发展的C9、C10和C6等3个桉树优良品系 这3个无性系4年生年平均树高和胸径生长量、每株干·a-1和4 2～7 5kg·材重量和纤维产量分别可达3 7～4 4m、3 3～3 7cm、9 2～16 1kg·株-1株\+-1·a-1,且抗逆性强、稳定性好、木材纤维形态和化学组成等良好特性,是制浆造纸优质原料     

木材商品市场特性初探

木材市场的特点在于:①木材市场需求的变化对木材供应与木材生产的调节作用是不同的;②同一市场信息对木材生产者存在双向的正负刺激;③木材市场机制对木材供给和木材生产的影响具有较大的延迟效应;④市场信号对林业生产的不良影响存在于供应环节;⑤现存的木材市场价格信号失真。     

Shape and distribution of knots in a sample of picea abies logs

In an attempt to develop a better understanding of the effect of knottiness on the yield of logs for sawn timber products, the present study examines the position and geometrical characteristics of 429 knots found in seven Norway spruce (Picea abies (L.) Karst) middle logs from southern Finland. The raw data used in this study were in the form of coordinates of points located on the knot surface recorded in a cylindrical (R, L, T) reference frame. The data were smoothed using a non linear three‐dimensional model. A curvature analysis of the knot pith was used to differentiate the curved and straight portions of the knots. This analysis made possible calculation of knot angles, symmetry, ovality and volume. The major finding of this study is the uneven distribution of knots around the log circumference. Nearly 50% of the total knot volume was concentrated in one‐third of the log facing the south‐east. Knots were also more prominent in higher portions of the logs studied. These observations support the argument that the uneven distribution of knots offers potential for improving the grade yield of timber sawn from trees harvested in high‐latitude countries.     

Failure criterion for timber beams loaded in bending,compression and shear

Abstract

Based on the elastic–plastic strength calculation, necessary for precise data explanation, a derivation is given of the failure criterion for combined bending, compression and shear. This exact limit state criterion should replace the unacceptable unsafe criteria of Eurocode 5 (EN 1995-1-1:2004). It is shown that the principle used thus far, of limited “flow” in axial compression as a determining failure criterion, for example, predicting no influence of a size effect, does not hold. Instead, it is derived and confirmed by the data that bending tension failure is always determining, showing the existence of a size effect, and correction of the existing calculation method is therefore necessary. Because of the primary importance of the size effect for the strengths, also for combined bending–compression, a simple derivation of the size effect design equations is given and discussed in an appendix.     

Multivariate product adapted grading of Scots Pine sawn timber for an industrial customer,part 2: Robustness to disturbances

ABSTRACT

Holistic-subjective automatic grading (HSAG) of sawn timber by an industrial customer's product outcome is possible through the use of multivariate partial least squares discriminant analysis (PLS-DA), shown by part one of this two-part study. This second part of the study aimed at testing the robustness to disturbances of such an HSAG system when grading Scots Pine sawn timber partially covered in dust. The set of 308 clean planks from part one of this study, and a set of 310 dusty planks, that by being stored inside a sawmill accumulated a layer of dust, were used. Cameras scanned each plank in a sawmill's automatic sorting system that detected selected feature variables. The planks were then split and processed at a planing mill, and the product grade was correlated to the measured feature variables by partial least squares regression. Prediction models were tested using 5-fold cross-validation in four tests and compared to the reference result of part one of this study. The tests showed that the product adapted HSAG could grade dusty planks with similar or lower grading accuracy compared to grading clean planks. In tests grading dusty planks, the disturbing effect of the dust was difficult to capture through training.     

大排距冲天炉性能分析

为了适应大规模、高效率的生产要求，对普遍冲天炉进行改进，设计出双排、大间距冲天炉。以前延用的是单排、独风口化铁炉，其存在熔化率低、铁水温度低、铁水成分不稳定、工人劳动强度大等缺陷，已不适合现代生产的要求。经改进设计后的冲天炉为双排、多风口，即每排４个风口，一菜８个风口。目的是人为地增加一层氧化一还原带，在炉内形成两个相互分开的燃烧带，使第一还原带的ＣＯ充分燃烧，并与得到充分预热的焦炭迅速发生反应，     

Improvement of Time-Driven Models of Lamina Cocksfoot Digestibility by a Process-Based Model to Take Account of Plant N Nutrition and Defoliation

For management purposes, models of lamina digestibility (D_W) that are thermal time driven (T_sum) fail to account for plant nitrogen status (0 < Ni < 1) and defoliation intensity (residual sheath height: S_r). The objective of this paper was to enrich them using a functional processed-based model, which assumes that the decline in D_W over time depends on the metabolic : structural tissue ratio and plant ageing. An experiment combining two N fertilizer rates and two defoliation regimes (differences in S_r) for two spring and two summer regrowth was done to analyse D_W of laminae (youngest fully expanded) and tiller (whole green lamina) levels. For laminae, we show that both processes contribute to explain the decline in D_W at a rate that depends on Ni but not on S_r. For tillers, consistent results were found justifying the use of a simple model: D_W = f(+Ni; −Ni × T_sum; −S_r). Two different databases (from experiment and commercial farms) were used for validation: RMSD varied from 35 to 49 g kg⁻¹. The process-based model strengthened the empirical model and improved the comprehensiveness of how management practices change D_W. We used both models to create applications for reasoning yield in function of herbage mass in complement than in function of time.     

定向结构板居室室内热环境的研究

运用温湿度自动记录仪对3种不同结构实体建筑的室内垂直空间的温湿度，墙体内外表面温度进行了监测，分析了建筑物的日平均温度变动比、衰减倍数。墙体内外表面以及室内垂直空间的温湿度分布，研究结果表明，内外表面均采用定向结构板，中间填充玻璃棉的复合墙体比传统砖墙的保温隔热性能好，能有效地抵抗外界大气环境对室内热环境影响的作用。     

木材内部腐朽特征识别专家系统

简单介绍了专家系统在林业上的应用 ,详细阐述了木材内部腐朽特征识别专家系统的设计过程。该系统可以为合理造材 ,提高木材的经济价值提供依据。