我国木材干燥设备市场亟待技术规范与正确导向

本文列举了我国木材干燥设备市场中大量技术混乱的事实，有针对性地提出了技术规范的依据，并就如何从技术与体制创新、木材干燥方法、木材树种、干燥设备、干燥工艺、配套系统等方面进行正确引导进行了探讨。     

我国木材干燥设备生产现状

我国木材干燥设备生产现状（１５００８６）全国林机情报网中心站邱曼萍木材干燥是木材深加工、精加工的重要工序和关键技术。先进的木材干燥设备是木材于燥不可缺少的．今年３月，北京“’９６国际木机展”国内厂家推出的木材干燥设备，基本上代表了我国木材干燥设备的生...     

我国常规木材干燥设备使用状况初探

我国的木材加工企业绝大多数使用的是常规木材干燥设备。本文对国产和进口的常规木材干燥设备进行比较，并提出改进建议。     

木材干燥学教学改革实践与体会

木材干燥学是木材科学与工程专业的一门专业课。其教学目标是使学生掌握木材干燥的基本理论和规律性，掌握木材干燥工艺，熟悉干燥设备，并获得选用、设计干燥设备的能力。木材干燥学也是一门集木材、热工、电气、机械、建筑、仪表、自动控制为一体的多学科性的应用学科。     

木材干燥的自动控制

随着科技的发展，自动控制在木材干燥上用得越来越多。进口干燥设备几乎全部采用自动控制。国产干燥设备也在逐渐向自动控制过渡。由于木材干燥的特殊性，自动控制种类繁多，方式各异，令人有无所适从之感。本文旨在帮助使用者对木材干燥的自动控制有全面的、清晰的了解，以便更好地选择和使用适合自己情况的自动控制木材干燥设备。1自动控制的类型木材干燥过程实际上就是干燥介质作用于木材的过程。在这一过程中，木材的性质无法改变，因此也无法控制。人们能够控制的只是干燥介质的性质。所以，干燥过程的控制实际上只是对介质条件的控制…     

新型热风加热木材干燥窑

介绍炉气间接加热木材干燥中的一种新方法－－新型热风加热木材干燥，简述了窑体和干燥设备的组成，结构特点，工作原理及其所具有的造价低，质量可靠，安全，节能等优良特性，说明热风加热木材干燥窑是中、小型木才加工厂较为理想的干燥设备。     

成材（板、方材）过热蒸汽-真空干燥技术

木材干燥是在热力作用下以蒸发或沸腾的汽化方式排除木材水分的处理过程。木材干燥是保存木材的优良特性、增强材质、合理利用木材的重要措施之一。 目前国内外普遍应用的木材干燥设备是蒸汽干燥和除湿干燥设备,拥有量占整个干燥设备的８０％以上,而过热蒸汽－真空干燥设备是近几年发展起来的一种新型木材干燥设备,用此种设备干燥的木材质量好,木材颜色变色小,是一种较为理想的木材干燥设备。１工艺理论基础 木材属于植物有机体,含有一定的水分。其作为原材料在加工利用时,水分的存在在大多数情况下是极为不利的,因为木材的物理力学…     

《木材干燥学》教学改革初探

《木材干燥学》教学改革初探高建民北京林业大学《木材干燥学》是木材加上专业的一门专业课。它的主要任务是使学生掌握木材干燥的基本理论与规律性，掌握木材干燥工艺，熟悉干燥设备，并获得干燥设备的选用、设计及计算的能力。《木材干燥学》多年来使用的教材内容较陈旧...     

木材除湿干燥技术特点及应用前景

木材除湿干燥技术始于60年代，首先在欧洲开始应用。80年代初，我国木材加工企业开始引进除湿干燥设备。1985年后，广东、山东等地有关机械厂，研制了国产除湿干燥设备，并开始在生产单位推广。1987年底，上海某研究所研制了高温热泵，其后，北京林业大学又研制了高温双热源热泵等，使除湿干燥技术在木材行业得到进一步推广。木材除湿干燥为木材干燥提供了一种新技术、新方法，为不少企业解决了木材干燥问题。但是，与此同时，由于对除湿干燥的原理、工艺、适用性、经济性等缺乏了解，也使一些企业遇到了各种各样的问题，如干燥周期长、残余…     

周期式短轴型木材干燥室湿度调节系统的设计

介绍了周期式短轴型木材干燥室的主要结构，分析了介质湿度调节系统在木材干燥设备工作中的重要作用，针对生产实际的效果，对湿度调节系统的设计进行了论述，并介绍了该系统的进排气道装置、增湿装置的结构设计、理论分析及设计计算方法与步骤。设计的木材干燥室设备，提高了木材干燥质量，达到了预期的效果。     

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.