杉木室外型中密度纤维板的制造工艺

采用正交试验法并对试验结果作统计分析 ,通过验证、跟踪试验 ,为杉木制造室外型中密度纤维板提供了依据。研究结果表明 :以杉木为原料制造室外型中密度纤维板是可行的 ;在本研究确定的施胶量、板密度及热压工艺条件下 ,实验室制得 9mm厚试验板材的所有性能指标均达到了国家标准的要求     

室外型中密度纤维板的制造工艺研究

本文主要探讨了以４，４’－二苯基－甲烷－二异氰酸酯（ＭＤＩ）为胶粘剂生产室外型中密度纤维板的制造工艺，同时研制了ＭＤＩ胶粘剂专门使用的脱模剂，以解决生产过程中的热压粘板的问题。用ＭＤＩ胶粘剂生产的中密度纤维板，其物理力学性能达到了欧洲中密度纤维板工业标准（ＥＭＢ－９５）中的室外型中密度纤维板指标。     

室外型中密度纤维板的研制

主要探讨了以4，4’一二苯基一甲烷一二异氰酸酯（MDI）为胶粘剂生产室外型中密度纤维板的制造工艺，同时研制了MDI胶粘剂专门使用的脱模拟，以解决生产过程中的热压粘析的问题。实验还表明：用MDI胶粘剂生产的中密度纤维板，其物理力学性能达到了欧洲中密度纤维板工业标准（EMB－95）中室外型中密度纤维析的指标。     

室外型中密度纤维板的制造工艺研究

本文主要探讨了以４，４’－二苯基－甲烷－二异氰酸酯（ＭＤＩ）为胶粘剂生产室外型中密度纤维反的制造工艺，同时研制了ＭＤＩ胶粘剂专门使用的脱膜剂，以解决生产过程中的热压粘板的问题。用ＭＤＩ胶粘剂生产的中密度纤维板，其物理力学性能达到了欧洲中密度纤维板工业标准（ＥＭＢ－９５）中的室外型中密度纤维板指标。     

防潮型中密度纤维板的研制

研究了以脲醛胶为主，三聚氰胺胶为辅制造防潮型中密度纤维板的工艺条件，讨论了热压时间、热压压力、热压温度、施胶量、配胶比例对中密度纤维板物理力学性能的影响。结果表明：配胶比例是重要的影响因子。采用试验所得的优选工艺制得的产品各项指标均达到或优于防潮型中密度纤维板国家标准。     

MUF-EMDI胶制备室外家具型中密度纤维板的工艺及性能评价

以乳化二苯基甲烷二异氰酸酯(EMDI)与三聚氰胺改性脲醛树脂(MUF)混合作为胶黏剂,制备室外家具型中密度纤维板(MDF-FN-EXT),探讨三聚氰胺用量、EMDI用量、热压时间对其防潮性能的影响。结果表明,以优化工艺参数EMDI用量4%,三聚氰胺用量9%,热压时间3 min制备的试板,性能指标满足GB/T 11718-2009《中密度纤维板》中室外家具型要求。     

杨木/狼尾草复合中密度纤维板工艺研究

研究了速生杨木/狼尾草复合中密度纤维板的工艺.试验结果表明:利用速生杨木和狼尾草制造脲醛树脂中密度纤维板是可行的,产品性能可以超过国家中密度纤维板标准的要求.该产品生产的较佳工艺为板材密度0.85 g/cm3,热压温度170℃,热压时间20 s/mm(板厚).     

湿地松制造中密度纤维板工艺的研究

以湿地松（Ｐｉｎｕｓｅｌｉｏｔｉ）为原料制造中密度纤维板工艺的研究,采用正交试验方法,分析了施胶量、板坯含水率、热压温度及热压时间对中密度纤维板物理力学性能的影响。试验结果表明：板坯含水率及热压时间对试验板质量影响较大,热压温度及施胶量的影响较小。采用适宜的工艺,即板坯含水率在１０％、热压温度１６５℃、热压时间５ｍｉｎ,施胶量可以降至８％～９％,试验板的各项物理力学性能可以达到国标特级品的要求。     

杨木/棉秆复合无胶纤维板制备工艺初探

以杨木和棉秆为原料,采用干法纤维板制备方法制成无胶木材/棉秆复合纤维板,研究了杨木和棉秆纤维比例、热压温度以及活化剂添加量对板材性能的影响.试验结果表明:以木材和棉秆为原料,不使用胶粘剂制造木材/棉秆复合无胶纤维板是可行的.随着棉秆比例的增加,板材强度略有提高,但吸水率也随之提高.提高热压温度和添加活化剂可以显著改善板材的吸水性.     

中国林业产业(人造板业)创新获奖项目案例(Ⅳ)

1 项目简介该项目是在多年喷蒸-真空热压技术研究的基础上和实施国家林业局科技成果推广项目"厚型中密度纤维板制造技术"中形成的,由南京林业大学和福建龙岩紫金集团永定紫金木业有限公司共同完成.项目针对目前国内缺少厚型中密度纤维板产品及制造技术,重点研究喷蒸-真空热压工艺、蒸汽喷射及真空抽吸系统以及厚型中密度纤维板后期加工技术三个核心问题,研究制造厚型中密度纤维板的最佳工艺参数,通过实验室试验和工业化生产试验,获得自主知识产权,形成了有自己特色的厚型中密度纤维板成套技术(包括工艺和设备),并在工业化生产中推广应用.该项技术可大幅度缩短生产时间,节省能耗,降低成本;产品及制造技术填补国内空白.     

Browsing Damage on Pine (Pinus sylvestris and P. contorta) by a migrating moose (Alces alces) Population in Winter: Relation to Habitat Composition and Road Barriers

In Scandinavia, moose (Alces alces L.) sometimes cause severe browsing damage to economically-important pine. Moose-vehicle accidents have spurred construction of fences along roads, and these may interfere with moose migration between summer and winter ranges, or the road alone may be a barrier. If this happens and moose build up along roads, landowners may suffer economically. Therefore, this study investigated whether roads, fences or other factors influence the use of young pine stands by moose. Eighty stands along roads in northern Sweden were evaluated in which individually-browsed branches were counted on 9972 pines. Moose browsing was not significantly related to birch (Betula pendula Roth, B. pubescens Ehrh.) density, nor did it differ between pines (Pinus contorta Douglas or P. sylvestris L.). However, increased pine density, site productivity and proximity to a highway were associated with increased browsing. Further large-scale studies are needed to understand moose habitat selection and the effects of roads.     

Effects of Root Freezing on the Physiology and Growth of Picea glauca,Picea mariana and Pinus banksiana Seedlings Under Different Soil Moisture Regimes

The root systems of 2-yr-old Picea glauca, Picea mariana and Pinus banksiana seedlings were submitted to various frost temperatures during an artificial frost to induce different levels of root damage. Frost-damaged and control seedlings were placed in a greenhouse under high and low soil moisture regimes. Seedling growth and physiology were evaluated periodically. Seedling survival was reduced when root damage reached levels of 60-80%. Root systems of all three species showed partial to total recovery by the end of the experiment. In general, root freezing damage caused reductions in seedling growth, with these reductions becoming less significant over time. Root damage had little to no effect on black spruce and jack pine seedling physiology, while white spruce CO 2 uptake decreased with increasing root damage. Shoot nitrogen content of all three species decreased slightly with increasing root damage.     

Stand Structure in Pine,Spruce and Deciduous Forests: A Comparison Between Finnish and Russian Karelia

This study investigated the stand structure in pine, spruce and deciduous forests in the border district of Finland and Russia. A total of 46 mature forest stands was selected as pairs, the members of each pair being as similar as possible with respect to their forest site type, age, moisture and topography. The stands were then compared between the two countries by means of basal areas and number of stems. The proportions of dominating tree species were 2-12% lower, and correspondingly the proportions of secondary tree species higher, in Russian forests. The density of the forest stock was also higher in each forest type in Russia. The forests in the two countries differed most radically in terms of the abundance of dead trees. The amount was two to four times higher in Russian deciduous and spruce forests, and in pine forests the difference was 10-fold. The stand structures indicated that Russian coniferous stands, in particular, were more heterogeneous than intensively managed pine and spruce stands in Finland.     

Growth and Terminal Bud Formation in Picea abies Seedlings Grown with Alternating Diurnal Temperature and Different Light Qualities

The root collar diameter and the height:diameter ratio are of particular importance in container-grown seedlings where a high density in the containers may produce spindly seedlings. Temperature regimes and light quality are known to affect plant growth. The aim of this study was to identify responses in Picea abies (L.) Karst. seedlings grown with light providing different red:far-red ratios and under temperature regimes with alternating day (DT) and night temperature (NT) from negative (DT < NT) to positive (DT > NT) difference (DIF) between DT and NT. Experiments were conducted in controlled environment chambers and in a daylight phytotron. Only limited thermoperiodic responses appeared in P . abies seedlings with respect to seedling height and dry weight accumulation. The formation of terminal buds, however, was clearly delayed in seedlings grown at negative DIF. The results indicate a requirement for day extension light that is high in far-red, to prevent terminal bud formation under natural short-day conditions. An extended study should be conducted to clarify the minimum level of light intensity and the optimal light quality needed to prevent terminal bud formation under natural short-day conditions.     

CAD与建筑设计的关系

本文分析了CAD在设计中引起的正面和负面影响,并进行了系统的阐述,从而使设计者在应用中能够保持客观的态度。     

Natural Regeneration in Clear-cuts: Effects of Scarification,Slash Removal and Clear-cut Age

The effects of soil scarification (mounding), slash removal and clear-cut age on the natural regeneration in clear-cuts was evaluated using data from four sites in southern Sweden. The treatments were carried out during a good seed and establishment year for birch ( Betula pubescens Ehrh. and B. pendula Roth). Scarification had the strongest positive effect on the density of naturally regenerated seedlings, especially in birch, but also in pine ( Pinus sylvestris L.) and spruce [ Picea abies (L.) Karst]. Slash removal had a positive effect on birch density. No statistically significant effect of clear-cut age was found. In addition, no statistically significant interactions between clear-cut age and scarification or slash removal were found. The ingrowth of field vegetation was the fastest in areas that were not scarified, less rapid in areas scarified on old clear-cuts, and the slowest after scarification in fresh clear-cuts. In conclusion, it may be possible to control the density of birch during a good establishment year for birch. If birch is desired, the best combination of treatments is to remove the slash and scarify; otherwise, these treatments should be avoided.     

Risk Perception Among Non-industrial Private Forest Owners

Based on an enquiry, risk perception among non-industrial private forest owners is described in relation to climate change and forestry hazards. Of the respondents, 11% took action to remedy the effects of climate change. Out of a given set, hazards were ranked according to each respondent's experience of recent substantial financial loss to the estate and in relation to his or her willingness to make investments aimed at risk reduction. For each hazard, the respondent assessed the risk in four classes ranging from very high to negligible risk. Six hazards were considered most problematic in all three aspects: browsing damage, falling timber prices, damage by wind, spruce bark beetle, root rot and pine weevil. A majority of the respondents claimed to take action to reduce the risk associated with at least one hazard, while 35% did not know whether they did. Excluding climate change, the need for decision support was the largest in relation to damage by wind owing to a combination of perceived high risk and a high level of ignorance in relation to whether risk-reducing measures were taken.     

Interactions in decomposition and N mineralization between tropical legume residue components

In situ produced plant residues contain a mixture of different plant components of varying quality. To assess synergistic or antagonistic interactions occurring during the decomposition and mineralization of such mixtures, individual plant parts (stems, leaves, leaf litter and roots) or the mixture of stems, leaves and leaf litter of the agroforestry species pigeonpea (Cajanus cajan) or of crop residues of peanut (Arachis hypogaea) or of the weed hairy indigo (Indigofera hirsuta) were incubated in pots for 19 weeks. Periodically, remaining plant residues were sieved out (>2 mm), weighed and N content as well as soil mineral N determined. Above- and below-ground residues of peanut decomposed fastest and showed the largest N release in agreement with their high N concentration and low-acid detergent fibre (ADF) : N ratio. Hairy indigo was hypothesized to be of lower quality than pigeonpea because of its high-polyphenol content. However, it decomposed faster than pigeonpea, largely because of the higher N and lower lignin concentration of its components. Ranking of individual plant components for N mineralization resulted in the following pattern, leaves > leaf litter > roots > stems. In mixtures of the different plant components a similar species order in decomposition was obtained, e.g. peanut > hairy indigo > pigeonpea. The amount of N released from the mixture was dominated by stem material that comprised 46–61% of the mixture. The interactions in mixtures were relatively small for peanut (generally high-quality components) as well as for pigeonpea (low proportion of high-quality components, i.e. N rich leaf material). However, a positive interaction occurred during later stages of N mineralization in the mixture of hairy indigo as it had a significant proportion of N rich components and absence of highly reactive polyphenols. Thus, for plants with low to intermediate chemical quality attributes, manipulating plant composition (e.g. by varying harvest age, affecting stem and leaf proportions) will be important to obtain significant interactions during decomposition when its components are mixed.     

Pasture production and tree growth in a young pine plantation fertilized with inorganic fertilizers and milk sewage in northwestern Spain

The use of organic waste materials such as milk sewage as an organic fertilizer could have the dual advantages of organic-waste disposal and reduced dependence on inorganic fertilizers. The effects of fertilization with (1) conventional mineral fertilization, (2) milk sewage sludge at 40 kg N ha⁻¹ target rate and (3) no fertilization on pasture production and tree growth were examined in an experiment consisting of two pasture mixtures under a one-year-old Pinus radiata plantation with a density of 2500 trees ha⁻¹. The two pasture mixtures were: (1) Dactylis glomerata L. var. saborto (25 kg ha⁻¹) + Trifolium repens L. group Ladino (4 kg ha⁻¹) + Trifolium pratense L. var. Marino (1 kg ha⁻¹); (2) Lolium perenne L. var. Tove (25 kg ha⁻¹) + Trifolium repens L. group Ladino (4 kg ha⁻¹) + Trifolium pratense L. var. Marino (1 kg ha⁻¹). The experiment began in the spring of 1995 using a randomized block design with three replicates in Castro Riberas de Lea (Lugo, Galicia, north-western Spain). Plot size was 12 × 8 m², with a 1 m buffer strip between plots. Two-year data showed that fertilization with either material had a positive effect on pasture production, with no significant difference between the two fertilization treatments. Tree growth in the milk sewage sludge plot was significantly higher than in the control plots. Inorganic fertilization increased pasture production, but affected tree growth negatively. The results show that milk sewage sludge could be used as a fertilizer in silvo-pastoral systems. This revised version was published online in June 2006 with corrections to the Cover Date.