浸渍薄木与杨木单板复合制备地板表板工艺研究

浸渍薄木与杨木单板复合制备地板的表板,与基材及背板胶合热压成复合地板。通过正交试验分析,以表面抗裂性、表面硬度和表面耐磨度为依据,得到浸渍薄木与杨木单板复合地板表板的最优工艺为浸渍薄木浸胶量为90%,杨木单板涂胶量为150 g/m~2,热压时间为6 min,热压温度为130℃。复合地板性能指标为:表面耐磨0.060 8 g/100 r,硬度为2.87 kN,没有出现表面龟裂,浸渍剥离合格。     

无醛大豆基胶黏剂细木工板热压工艺研究

以热压温度、热压压力、施胶量为影响因素设立正交试验,采用杉木芯板和桉木单板为原料,测试产品的横向静曲强度和浸渍剥离长度,对无醛大豆基胶黏剂细木工板热压工艺进行了研究。结果表明:当杉木板芯厚度为11.5 mm、桉木单板厚度为2.6 mm、热压时间为8 min时,最佳工艺参数为热压温度125℃、热压压力1.2 MPa、单面施胶量250 g/m2。各因素对细木工板力学性能和耐水性能影响的主次为施胶量热压温度热压压力。     

实木复合地板的表层改性工艺

将表层橡木单板浸渍三聚氰胺树脂后,与桉木单板、三聚氰胺浸渍纸一次热压成型制作多层实木复合地板。采用正交试验方法,探讨橡木单板浸渍工艺及热压工艺对多层实木复合地板表面耐磨性等理化性能指标的影响。试验结果表明:浸渍温度对橡木单板浸渍质量增加率影响显著,浸渍浓度对橡木单板浸渍质量增加率影响一般显著,热压温度对多层实木复合地板的表面耐磨性能影响显著。在试验条件下,以浸渍时间20 min、浸渍浓度40%、浸渍温度45℃、热压温度145℃、热压时间0.8 min/mm、热压压力1.8 MPa和施胶量240 g/m2为较优工艺,压制所得多层实木复合地板的表面耐磨性能等理化性能较佳。     

橡木贴面实木复合地板凹凸表面热压工艺研究

三聚氰胺浸渍橡木薄单板贴面实木复合地板是参考三聚氰胺浸渍纸贴面生产工艺生产出的表面凹凸实木复合地板。使用三聚氰胺胶黏剂、固化剂、渗透剂、脱膜剂（配比为500：1：1：1）混合液浸渍橡木薄单板,然后在真空度为0.08 MPa时保压浸渍5 min,在大气条件下放置30 min,取出后再放入90℃鼓风干燥箱中干燥10 min。浸渍完成的橡木薄单板与基材经热压成型为表面凹凸的实木复合地板。考虑热压温度、热压压力、热压时间对其凹凸表面成型的影响,每个因素取4个水平,制定因素水平表,选择正交表进行试验。对试验结果进行浸渍剥离及表面纹理深度的测量分析,得到最优的热压工艺条件为温度150℃、压力1.2 MPa、时间70 s。三聚氰胺浸渍的橡木贴面复合地板表面纹理、色泽、手感都更加接近自然。     

水性环氧树脂制备桉木单板层积材及性能研究北大核心

选用双组分水性环氧树脂为胶黏剂,速生桉木单板为基材,热压制备结构用桉木单板层积材。采用单因素试验法研究了施胶量、热压温度、热压时间、热压压力对水性环氧树脂单板层积材弹性模量、静曲强度、水平剪切强度、含水率和浸渍剥离率等物理力学性能的影响。结果表明:水性环氧树脂以水为分散剂,在木质单板表面延展性良好。当施胶量为230 g/m^(2),热压温度为120℃,热压时间为1.0 min/mm,热压压力为2 MPa时,单板层积材各项性能较优,符合GB/T20241—2006《单板层积材》要求。提出的以水性环氧树脂为胶黏剂的层积材制备工艺适合工业化生产,产品力学性能优良且无醛/低醛释放,绿色环保,具有积极的推广意义。     

意杨木材层积塑料制造工艺研究

用低分子量酚醛树脂胶对意杨旋切单板进行浸渍处理,采用单因素试验法,探讨了热压压力对产品性能的影响,分析各压力水平下板材的密度、含水率、顺/横纹抗弯弹性模量、冲击韧性等物理力学性能,得出符合要求的热压工艺参数。结果表明:在热压单位压力3.5 MPa,热压温度150℃,热压时间5 min/mm条件下,板材的力学性能和尺寸稳定性能最佳。     

桤木旋切单板以及用于制造细木工板的工艺研究

通过设置不同的旋切厚度对不同树龄的桤木原木进行单板旋切试验,分析单板厚度和背面裂隙率,探讨桤木单板旋切的适应性和制造细木工板的工艺,并采用正交法优选最佳制造细木工板的热压工艺参数。结果表明:当杉木板芯厚度为12 mm、桤木单板厚度为2.8 mm时,热压温度为125℃、热压压力为1.3 MPa、热压时间为8 min、施胶量为220 g/m~2时,横向静曲强度最大。     

脲醛树脂泡桐单板层积材的生产工艺

对以兰考泡桐旋切单板和脲醛树脂胶为原料制造单板层积材的工艺进行了研究.结果表明,热压温度为130 ℃,热压时间为1.4 min/mm板厚,双面涂胶量为380 g/m2,泡桐木单板层积材的物理力学性能良好,各项性能指标均可达到室内用材要求.     

竹炭／TiO2复合体改性杨木单板的胶合性能

采用加压浸渍法将负载型光催化材料--竹炭/TiO2复合体渗入杨木单板中,运用正交试验方法对纳米TiO2改性杨木单板的胶合性能进行了研究,探讨涂胶量、热压压力与浸渍压力等因素对材料胶合性能的影响,并结合扫描电镜分析给出了制板的最佳工艺条件:热压压力为1.2 MPa,浸渍压力为1.6 MPa,涂胶量250 g/m2.     

热压工艺对密实型杉木单板层积材力学性能的影响

以自制低分子量酚醛树脂为胶黏剂,采用热压工艺对杉木单板进行密实化试验,研究干燥温度、压缩率、热压温度和热压时间对密实型杉木单板层积材力学性能的影响.结果表明:压缩率对层积材力学性能影响最大,其次是干燥温度、热压温度和热压时间;随着压缩率和热压温度的提高,板材的MOE、MOR都有不同程度的提高;随着干燥温度的提升和热压时间的延长,板材的MOE、MOR都呈先增大后减小的趋势;综合考虑,确定密实型杉木单板层积材的最佳热压工艺为:干燥温度60℃、压缩率35％、热压温度145℃、热压时间1.0 min/mm,在此热压工艺条件下制得的板材,其MOE和MOR分别达到了GB/T 20241-2006《单板层积材》120E级和180E优级.     

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.