水泥刨花板快速固化工艺的研究

以毛白杨、兴安落叶松和普通硅酸盐水泥为主要原料，采用二氧化碳气体喷射法研究水泥刨花板的快速固化工艺，探讨了水灰比、二氧化碳气体压力，养护条件等对水泥反应特征和水泥刨花板性能的影响。结果表明，最佳制板工艺参数为：ＣＯ２气体压力０．７ＭＰａ，通气时间３ｍｉｎ，木灰比０．２（毛白杨）或０．５（落叶松），水灰比０．３５（毛白杨）或０．４（落叶松）；水灰比不但影响成板的可能性，而且对反应特征和水泥刨花板的力     

竹木混合水泥刨花板工艺初步研究

研究了热压法制造竹木混合水泥刨花板工艺并对影响板材性能的因素进行探讨。结果表明:竹刨花水煮预处理后所制备的板材性能较好;本实验范围内,竹木混合水泥刨花板较合适的工艺参数为竹木比1∶3、灰木比4∶1、热压时间1～2min/mm板厚、CaCl2用量为灰重的5%、水灰比0.4。     

原状粉煤灰在水泥刨花板中应用的研究

主要论述了原状粉煤灰（Ⅲ级灰）在水泥刨花极中应用的情况。分析了在其它工艺条件（密度、水灰比、木灰比）确定情况下,粉煤灰替代量、外加剂种类和用量等因素对板各项性能指标的影响。结果表明：（１）粉煤灰替代量是影响极材性能的主要因素,外加剂种类和用量对极性能也有影响;（２）粉煤灰替代量３０％为强度转折点,但４０％替代量制板,板各性能指标仍然能达到国家行业标准要求;（３）以粉煤灰替代部分水泥生产水泥刨花板。不但可以降低生产成本,而且可以改善板的某些性能。     

杨木水泥刨花板工艺的研究

对杨木水泥刨花板的物理力学性能与主要工艺参数——密度、木灰比、水灰比、添加剂及添加量的关系作了研究。结果表明,密度(D)对板材性能影响最大,木灰比(W/C)次之,水灰比(W_1/C)最小;板材的主要性能如MOR、MOE、IB同密度、木灰比、水灰比的关系,可用方程Y=a_0+a_1D+a_2(W/C)+a_3(W/C)~2+a_4(W_1/C)+a_5(W_1/C)~2表示;在各种添加剂中,以氯化钙的效果最好。     

半干法粉煤灰水泥刨花板的生产工艺

通过改进粉煤灰水泥刨花板的生产工艺,在不改变水泥的等级、保证板材力学性能的前提下,选择粉煤灰的替代比例、添加剂的种类、用量以及密度、水灰比和灰木比等因子进行试验,以确定粉煤灰水泥刨花板的最佳工艺.     

新材料─—粉煤灰刨花板的研制

本文对两家电厂的粉煤灰进行了粉煤灰刨花板制造工艺的研究。研究结果表明：１．助剂种类及添加量应根据粉煤灰化学成分和品质的差异而有所区别。２．灰木比是影响板材物理力学性能的最显著因素，灰木比的取值范围在２：１～４：１可制出合格板材。３．密度对板材强度的影响极为明显，粉煤灰刨花板密度不宜低于０．９０ｇ／ｃｍ￣３。４．增加施胶量虽然可以提高板材强度，但施胶量大于９％对强度的影响已不明显。本文还就生产性试验、初步经济分析、市场前景进行了简要说明。     

灰木比对水泥刨花板力学性能的影响

对不同灰木配比的水泥刨花板力学性能进行试验研究,结果表明:在研究范围内水泥刨花板的密度、内结合强度、弹性模量和静曲强度都随灰木比的升高而增强,吸水厚度膨胀率随着灰木比的升高而降低。当灰木比为1:1时,板材的静曲强度为8.4 MPa;当灰木比为1.5:1时,板材的静曲强度为14.6 MPa;当灰木比为2:1时,板材的静曲强度为15.6 MPa水泥刨花板的力学强度在灰木比为2:1时达到最高。     

快速固化水泥刨花板的工艺试验

以速生杉木加工剩余物为主要原料、Na2SiO3为快速固化添加剂制备水泥刨花板,研究了冷、热压两种压板方式、Na2SiO3添加量、热压温度、热压时间、水灰比、灰木比、水泥种类和刨花形态等因素对水泥刨花板主要性能的影响.结果表明,热压法可适用于水泥刨花板制造,最佳工艺条件为:Na2SiO3添加量10%、热压温度95℃、热压时间12 min、水灰比0.6、灰木比2.6,制备的水泥刨花板的静曲强度达到10 MPa;采用MgCl2后处理能显著改善板的性能.     

粉煤灰彩色复合饰面砖

在粉煤灰微混凝土砖的基础上，复合上一层装饰表面，开发出一种成本低、档次高的装饰新产品──粉煤灰彩色复合饰面砖。 这种饰面砖为基层和彩色层两层结构： １．基层采用粉煤灰、渣、水泥、水、外加剂，配比为：粉煤灰３２％～４０％，渣５０％～６０％，水泥８％～１０％，总重量１０％～１８％的水，总重量０．０３％的外加剂； 基层材料中粉煤灰采用电厂的细灰，粒径０．５цｍ～３１５цｍ；渣采用锅炉底部排除的煤燃烧后形成的粗渣，粒径在０．６３ｍｍ～５ｍｍ；水泥为普通的水泥；外加剂采用有机材料丙烯酸醋共聚物和无机材料二氧化硅组成的乳液状的有机、无机纳米杂化材料。 ２．彩色层厚度在３ｍｍ～６ｍｍ，分为自然色和染色两种合成方法； ２．且自然色合成法 采用自然彩色石硝４０％，粒径ｌｍｍ以下。自然彩色颗粒石３５％～４０％，粒径ｌｍｍ～２ ｍｍ。白水泥２０％～２５％，总重量８％～１２％的水，总重量０．０５％的外加剂。 ２．２＄色合成法 采用漂染石硝４０％，漂染颗粒石３５％～４０％，彩色或颜料调理水泥２０％～２５％，总重量８％～１２％的水，总重量０．０５％的外加剂。 该复合饰面砖的工艺过程为： １．按配方将基层干物料预搅拌２分种； ２．水与外加...     

浅色水泥锯屑板的研制开发

采用白水泥细锯屑作面底层,灰水泥粗锯屑作芯层,分层分色铺装,试制成浅色水泥锯屑板。初步分析了密度、木灰比、水灰比、化学助剂和板坯结构对板子物理力学性能的影响,取得了较佳的工艺参数。     

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.