板木家具设计中实木构件与人造板基材构件的配置方法

由于人们对实木家具情有独钟,但实木资源尤其是珍贵树种资源日趋减少,因此,具有实木外观形象特征又减少实木用量的板木家具应运而生,并已成为当今中国木质家具市场的主流产品类型之一。按照基材类型不同,板木家具的构件主要分为两种:实木构件、人造板基材构件。板木家具设计时,设计师最难把握的是家具的哪些构件用实木构件、哪些用人造板基材构件。因为人造     

浅析板木家具的结构设计

<正>近年来,由于木材价格的持续上涨,直接导致实木家具价格的攀升,在此形势下,直接催生出"板木家具"(frame-board type furniture,FBF)这一新型家具品类。板木家具是介于板式家具和框式家具之间的一类家具总称。由于目前板木家具还没有明确的定义,笔者结合市面上流行的"板木家具"含义和木家具通用技术条件(GB/T 3324—2008),暂且将板木家具从广义和狭义上分别进行描述。广义的板木家具可以理解为实木与木质人造板混合制作的一类家具。狭义的板木家具,主要是指家具框架或主要受力构件采用实木或板木构件制作,而其他如侧板、底、顶、隔板等非受力及展示部位     

板木家具实木化设计方法研究

概述了板木家具实木化结构分类;介绍了板木家具通过材料以及结构形态设计表现实木质感的形式,从结构形态和材料两个维度,以及零部件实木化和结构组合实木化两个层面,探讨了提升板木家具实木质感的设计方法。阐述了该设计方法在板木桌类、椅类、床类、柜类家具设计中的具体应用。该设计方法可以减少优质木材资源的利用,有效增强板木家具的实木质感。     

板木家具结构探析

<正>1板木家具定义板木家具是指用实木与人造板混合制作的家具。具体就是指其框架及主要部分采用实木,而其他如侧板、底、顶、隔板等非受力及展示部位用表面装饰过的人造板制作,其部件和部件之间,部件与零件之间采用五金件、圆榫或简易的方榫进行连接,其整体形态极似实木家具。     

增强板木家具实木感的设计方法

在绿色环保理念的感召下,实木家具成为消费者喜爱的家具类型,但随着木材价格的上涨,实木家具产品的价格随之攀升,一般消费者难以承受这高昂的价格。这种矛盾导致了板木家具(frame-board typefurnitureFBF)的诞生。板木家具是外形介于板式家具和框式家具之间、给人以实木造就之观感的一类家     

木家具工艺过程数字化管理平台构建与应用北大核心

从分析构建木家具工艺过程技术规范数字化管理平台的必要性入手,提出了构建木家具工艺过程技术规范数字化管理平台系统的基本架构——实木家具零件基础信息管理系统、实木家具制造工艺规划体系系统和实木家具生产过程监控与信息处理系统,探讨了基本架构中各模块的功能和特点,并对木家具工艺过程技术规范数字化管理平台的可视化监控的基本过程与流程进行了分析,在此基础上,总结了信息同步方法与管控过程的相应技术——零部件信息的数字化管控、工艺规程的标准化管控、可视化零部件生产车间全程监控,由此实现实木家具企业工艺过程连续信息流的全集成,为木家具生产机加工车间提供一个具有快速反应、有弹性、精细化特点的制造环境。     

木家具工艺过程数字化管理平台构建与应用

从分析构建木家具工艺过程技术规范数字化管理平台的必要性入手,提出了构建木家具工艺过程技术规范数字化管理平台系统的基本架构——实木家具零件基础信息管理系统、实木家具制造工艺规划体系系统和实木家具生产过程监控与信息处理系统,探讨了基本架构中各模块的功能和特点,并对木家具工艺过程技术规范数字化管理平台的可视化监控的基本过程与流程进行了分析,在此基础上,总结了信息同步方法与管控过程的相应技术——零部件信息的数字化管控、工艺规程的标准化管控、可视化零部件生产车间全程监控,由此实现实木家具企业工艺过程连续信息流的全集成,为木家具生产机加工车间提供一个具有快速反应、有弹性、精细化特点的制造环境。     

现代板木家具新型接合结构设计

通过分析家具设计的时代背景,提出可拆装结构的家具将是未来家具发展方向之一。可拆装板木家具设计的关键在于板材部件和接合方式的设计,通过具体实例的分析和展示,以期为拆装式板木家具发展起到抛砖引玉的作用。     

我国传统竹木家具造型中“线”的比较研究

文章阐述了中国竹、木家具线条构成的分类。从竹和木家具的材料、接合方式、审美差异出发,对竹和木家具框架线造型样式、连接线造型样式、装饰线造型样式3个方面进行了比较,分析了竹、木家具在线条使用上的相似性和差异性;并且通过对竹、木家具不同线条使用的分析,比较了两者在使用和审美双重意义上的异同,为竹家具的创新设计提供指导和借鉴。     

浅谈家具生产中多层胶合弯曲成型工艺

曲木家具有造型独特、外观优美、线条流畅、简洁大方的特点,表现出高雅、浪漫的气息。在家具生产中,弯曲零部件数量很多,形状及尺寸各异,目前在家具厂弯曲木的主要工艺如下: (1)实木锯制拼接工艺:采用实木拼条拼成大幅     

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.     

Decomposition and nutrient loss from prunings of different contour hedgerow species in tea plantations in the sloping highlands of Sri Lanka

Contour hedgerows of multipurpose tree species in the sloping tea lands of Sri Lanka are expected to reduce soil erosion and also add significant amounts of plant nutrients to the soil via periodic prunings. The objective of this experiment was to characterize the biomass decomposition pattern and quantify the amount of nutrients added through prunings of six tree species (Calliandra calothyrsus, Senna spectabilis, Euphatorium innulifolium, Flemingia congesta, Gliricidia sepium and Tithonia diversifolia) currently being used in hedgerows associated with tea. Withered leaf and stem prunings (50 g) were enclosed in 2-mm litter bags, placed at 5-cm depth and retrieved after one, three, six, nine and 12 weeks. Loss of initial dry weight, N, P and K was measured. Single exponential decay function adequately described both dry weight and nutrient loss. Tree species differed significantly in their rate of breakdown with decomposition constants (k) varying from 0.0299 to 0.2006 week⁻¹ for leaves and from 0.0225 to 0.0633 week⁻¹ for stems. Gliricidia showed the highest k for leaves with the rest in the following descending order: Senna > Tithonia ≥ Euphatorium > Calliandra > Flemingia. A similar pattern was observed for loss of all nutrients with Calliandra and Flemingia always having lower k values than the rest. Although N immobilization was not observed, immobilization of P and K was observed during the first week of incubation in some species, particularly in stem prunings. Annual biomass of prunings differed significantly between tree species in the following descending order: Calliandra > Senna > Flemingia > Tithonia > Gliricidia > Euphatorium. Calliandra added the greatest amount of nutrients annually to the soil with Euphatorium adding the least. Calliandra prunings provided the annual total K requirement and 49% of the N requirement of mature tea. However, none of the species provided more than 5% of the P requirement. It is concluded that among the tree species tested, Calliandra and Flemingia are the most suitable for contour hedgerows in tea plantations of this agroclimatic region because of their higher soil nutrient enrichment capacity and slower decomposition rates which would minimize leaching losses. This revised version was published online in June 2006 with corrections to the Cover Date.     

Growth of Phlebiopsis gigantea in wood of seven conifer species

Heterobasidion parviporum and Heterobasidion annosum are widely distributed root‐rot fungi that infect conifers throughout Europe. Infection of conifer stumps by spores of these pathogens can be controlled by treating fresh stumps with a competing non‐pathogenic fungus, Phlebiopsis gigantea. In this study, growth of three Latvian strains of P. gigantea and the biological control agent ‘Rotstop’ strain was evaluated in stem pieces of Norway spruce, Scots pine, lodgepole pine, Douglas‐fir, Weymouth pine, Siberian larch and Sitka spruce. The growth rates of one H. parviporum and one H. annosum isolate were also measured in the same stem pieces. The growth rate of P. gigantea varied greatly in wood of different conifer species. It was higher in the three pine species, lower in Norway spruce and lowest in Sitka spruce and Siberian larch, and in Douglas‐fir, this fungus did not grow. The largest area of wood occupied by P. gigantea was in lodgepole pine. Growth of Latvian isolates of P. gigantea in the wood of Pinus and Picea species was comparable to that of the Rotstop isolate. Consequently, stump treatment with local P. gigantea isolates should be recommended. However, our results suggest that Douglas‐fir stump treatment against Heterobasidion by P. gigantea may be ineffective and other stump treatment methods should be considered.     

Effects of Seed Weight and Seed Type on Early Seedling Growth of Pinus sylvestris under Harsh and Optimal Conditions

The effects of seed weight and seed type on seedling growth of Pinus sylvestris (L.) were studied by seeding individually weighed orchard and stand seed in different mixtures under harsh (direct seeding in field) and optimal (seeding in nursery) conditions. In the nursery experiment an increase in the seed weight from 3 to 7 mg increased the seedling height by 10-27% and total weight by 27-113%, and decreased the height/diameter ratio by 5-6% after 2 yrs. With elimination of seed weight effects, orchard seedlings were 2% taller than stand seedlings in year 2. Without elimination of seed weight effects, orchard seedlings were 7-13% taller. In the field experiment an increase in the seed weight from 3 to 7 mg increased seedling height by 18-65%, stem volume by 81-274% and the number of top-buds by 23-34% in year 5. After elimination of seed weight effects, orchard seedlings were 7-13% taller than stand seedlings and without elimination of seed weight effects 20-21% taller after 5 yrs. Even after elimination of both seed weight and genetic effects orchard seedlings were 3-9% larger than stand seedlings in the field experiment. In conclusion, the influence of seed weight and seed type on growth traits and slenderness is highly significant and the influence seems to be greater in harsh conditions.     

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。     

Potential to harness superior nutritional qualities of exotic baobabs if local adaptation can be conferred through grafting

Baobab leaves form an important part of the local diet in Sahel countries and elsewhere in Africa. Existing leaf nutritional data and agroforestry performance information are based solely on Adansonia digitata L., the baobab of continental Africa. The introduction potential of Adansonia species from the center of diversity in Madagascar and from Australia remains untapped. To assess this potential, the mineral contents and B₁ and B₂ vitamin levels of dried baobab leaves were determined for five-year old trees of A. digitata, A. gibbosa (A. Cunn.) Guymer ex D. Baum, A. rubrostipa Jum. & H. Perrier (syn. A. fony Baill.), A. perrieri Capuron and A. za Baill. grown in an introduction trial in Mali. Nutritional data were evaluated against survival and vigor to identify promising germplasm. Leaf vitamin and crude protein contents were highest in the Madagascar species, especially A. rubrostipa (B₁ 88 mg 100 g⁻¹, B₂ 187 mg 100 g⁻¹, protein 20.7% dry weight). However, the local species far outperformed the introductions in survival, tree height, basal diameter and resistance to termites. We suggest grafting as a way of harnessing the vigor of well-adapted local baobab varieties to the superior nutritional profiles of A. rubrostipa and others. Cross-species grafting tests in Adansonia were successful, thus creating new agroforestry possibilities with different scion/rootstock combinations.     

Modelling of adequate pretwist for obtaining straight timber

Abstract

Wood in general and wooden studs in particular are often distorted owing to uneven shrinkage during the drying process in the sawmill. Twist is often the most detrimental of all types of distortion, and it is caused by spiral grain in combination with variations in moisture content. For sawmills, the objective is to produce dried, straight boards, and one method of dealing with boards with excessive spiral grain is to sort them out and then dry them in a pretwisted position to obtain straight boards after drying. A model using the finite element (FE) method for the simulation of drying twist distortions was first calibrated against laboratory experiments in which boards were dried with and without restraints and pretwists. After the calibration, the FE results were compared with industrial test results for boards that were dried without restraints or with restraints with zero pretwist, i.e. straight restraints. The FE model used an elastic–ideally plastic material model to obtain permanent deformations. The calibration was to set the yield stresses so that there was a good match between FE results and results from the laboratory experiments. The comparison between the industrial test results and the FE results showed that the FE model is capable of realistic simulations of drying boards with and without restraints and presumably also pretwists.