轻型木结构建筑剪力墙热湿性能模拟与长期舒适度预测

按照我国4个主要建筑气候区域,以呼和浩特、银川、南京及广州4个具有典型气候特征的地区为例,采用瞬态热湿传送模型(WUFI),对国家建筑标准设计图集14J924《木结构建筑》中设计的4种不同构造形式的轻型木结构墙体进行10年期的热湿模拟预测,探究4种墙体使用中的建筑室内温湿度变化规律及居住舒适度。结果表明:在模拟的10年时间内,4种轻型木结构墙体的内外温湿度均相对稳定,具有良好的保温调湿作用,可以满足人们实际居住要求。     

刨花板轻质墙伸缩缝的研究

伸缩缝是指为适应气候条件变化引起墙板线性膨胀或收缩而预留的墙体缝隙。本研究通过模拟室内墙体使用状况，探讨了不同龙骨结构墙体模型在不同相对湿度条件下伸缩缝的变化。结果表明，饰面封边脲醛胶刨花板可用作厨房等潮湿环境的墙体材料，未饰面刨花板不适宜直接作为墙体材料，刨花板墙体伸缩缝以预留2．0～3．0mm／m为宜。     

竹材液化树脂发泡材料的降解性能和热老化性能评价

将竹材液化树脂发泡材料分别置于土壤微生物侵蚀、干(湿)热老化、氙光辐照条件下一定时间,采用热重、红外及电镜扫描法,对比分析处理前后材料的性能变化.结果表明,该材料易于被微生物降解;经干热、湿热老化处理后,材料的质量降低,压缩强度反而提升;经氙光辐照处理后,其质量和压缩强度下降.在实际应用中,该材料经覆面处理后,可作为芯材,用作建筑外墙保温材料.     

预制木质外墙挂板在建筑节能改造中的应用

改变墙体的热工性能以满足室内热舒适性要求,是建筑节能技术的关键。基于国内建筑节能改造现状以及外墙木质挂板、木构墙体等相关保温技术的研究成果,提出一种集节能、环保、防火、美观一体化的预制木质外墙挂板设计方案,并分析其热工性能和材料成本。     

聚苯板外保温技术

聚苯板外保温技术本项目提供有关节能墙体聚苯板（ＥＰＳ）外保温的全套技术，包括型材设计，施工方法、材料配制与应用。技术特点，在外墙主体结构外侧面贴ＥＰＳ板，形成连续保温层，在保温层外表面做保护层和饰面，完全解决了内、外墙连接节点及楼板和圈梁等部位的热桥...     

毛细管网吊顶辐射空调与新风耦合的性能研究

对毛细管网结构研发及供冷性能进行测试,并应用 Fluent数值模拟,对毛细管辐射供冷末端与置换通风和贴附射流两种通风方式加以耦合,通过实验验证了其模拟模型对该实验系统具有相关适用性,并应用了该相关模型。结果表明：两种不同的送风方式下,房间的三度均能满足舒适性要求,当热湿负荷突然增加时,如不采取相应的响应动作,毛细管辐射板表面将会有结露现象发生,置换通风较为严重,相同的新风条件下,贴附射流的通风方式,对于消除辐射板结露效果明显。     

复合墙体保温层布置形式对建筑采暖能耗的影响研究

本文利用建筑能耗模拟软件Energy Plus,对位于哈尔滨某办公建筑进行了采暖能耗模拟,计算了具有相同热阻的7种不同保温层布置形式的外墙建筑采暖总能耗及建筑的采暖峰值负荷。通过研究发现,改变墙体保温层的布置形式对建筑的采暖总能耗及采暖峰值负荷有一定的影响。在7种墙体中,墙体5的采暖总能耗最小,为337.81GJ。墙体2的采暖峰值负荷最小,为5853KW。墙体2的采暖总能耗及峰值负荷在几种墙体里均为最大。本文的研究成果将对保温墙体的生产设计起到一定的指导作用,并对我国未来的建筑节能工程有着积极的推动作用。     

浅谈建筑物外墙外保温面层裂缝控制原则及技术

外墙保温隔热是建筑节能的主要措施之一,而外墙保温面层的裂缝成为保温建筑质量中的重症,其抗裂性是墙体保温体系中要解决的关键技术之一。一旦保温层、保护层发生开裂,墙体保温性能就会发生很大改变,非但满足不了设计的节能要求,甚至会危及墙体的安全;针对外墙保温体系的特点,对其产生裂缝的原因进行分析,并提出一些控制措施,改进施工技术与方法,完善外墙保温工艺技术,为类似工程提供借鉴。     

正交胶合竹墙体的保温隔热性能

文中介绍了一种新型工程竹产品——正交胶合竹（CLB）。已有试验对CLB墙体在稳态传热过程下的保温性能进行了探究，为进一步研究CLB墙体在室外综合温度周期性变化作用下的传热过程并探究采用CLB墙体的竹结构房屋的能耗情况，通过建立在稳态传热过程下CLB墙体的有限元模型并与已有试验结果对比验证了其有效性，从而进一步建立了受到室外综合温度作用下的5种墙体模型，以此分析CLB墙体在非稳态传热条件下的保温性能以及不同保温方式对于CLB墙体保温性能的影响，最后通过DeST对CLB墙体房屋进行能耗分析。结果表明：研究建筑墙体受到的温度作用时，太阳辐射引起的当量温度不应忽视；CLB墙体拥有优越的保温性能，采用CLB墙体的建筑室内热环境稳定；无论夏季或冬季，保温层最合理的位置在CLB墙体的外侧；围护墙体采用CLB墙体的竹结构能够达到江苏省居住建筑节能率65%的水平。     

轻型木结构剪力墙保温性能测试与分析

以国内首栋六层梁柱框架-轻型木结构剪力墙——山东鼎驰木业有限公司研发大楼为研究对象，对其一楼质检部墙体A与二楼仓库墙体B的传热系数进行测定分析。热流计分别呈横向与纵向布置，分别采取空调加热和电暖器加热，测试不同部位墙体的保温隔热性能；参照标准GB 50176—2016计算墙体理论传热系数；采用Abaqus软件对墙体传热系数进行模拟并对墙体内部温度与热流密度分布展开分析。研究结果表明：墙体A(横向)与墙体A(纵向)的平均传热系数分别为0.463、0.465 W/(m²·K)，墙体B的平均传热系数为0.374 W/(m²·K)，均达到了寒冷地区甲类公共建筑外墙标准；各测点传热系数实测值有一定差异，墙体保温性能不均匀，受施工条件与结构形式影响较大；墙体传热系数的理论结果与数值模拟结果分别为0.238 W/(m²·K)和0.233 W/(m²·K)；保温层墙骨柱区域热流密度相比于保温棉区域显著提高，墙骨柱处易形成热桥，导致热流量和传热系数大幅上升，保温隔热性能下降。     

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.