在线板材厚度检测方案的探讨

1 在线板材厚度检测方案的比较根据我国板材标准,要求板材厚度检测到毫米,不足1mm的舍去,因此要求检测精度在1mm以下.而板厚的变化范围是2cm～8cm,超过8cm为方材.在这样范围大、精度高的情况下,要想在线非接触自动检测板厚,在技术上存在很多困难.采用象测宽一样的激光扫描法也不可行,因为板厚检测是     

板材弹性模量数控检测设备研究的发展

在论述目前国内外板材弹性模量检测设备研究现状的基础上，提出了目前板材弹性模量检测设备的发展方向，弹性模量检测技术将向应用于生产实际、节约原材料、保证产品安全可靠、实现质量自动控制、提高劳动生产率等全自动化的方向发展。通过与传统的检测方式对比，指出板材弹性模量检测设备应向NDT(无损检测)方向发展，将数控技术与弹性模量检测设备相结合，实现高质量、自动化和节约成本。提出的在线检测板材弹性模量数控检测设备将满足人造板和板材检测的市场需求。     

基于单片机的板材在线动态称重系统的设计

目前国内人造板行业发展迅速,但是人造板特别是单板层积材,不管在其生产设备还是质量控制和检测方面都还需要进一步完善和改进。板材密度是检测板材强度的重要指标之一,对板材的机械、物理性能影响很大。通过对在板材的重量(质量)的在线检测,结合几何     

测试条件对室外人造板吸水性能的影响

进行了不同条件下5种室外人造板吸水率试验,结果表明:室外竹质人造板的耐水性优于室外木质人造板,水的温度、浸渍时间对板材吸水率影响最大,温度增高、浸渍时间延长,吸水率增大,浸渍时间应不低于72h;水的pH值对板材吸水率影响不大且不呈现规律性,pH值在6或7时吸水率最大；板材厚度小时吸水率较大,厚度增大时吸水率相对偏小并趋于平稳；试件尺寸越大,吸水率越小.     

GreCon在中国市场首次推出远程控制技术

GreCon（格雷康）总部位于德国汉诺威近郊的阿尔费尔德，始建于1911年，在全球各地设有多处分公司和代表处及代理商。其所属的法古斯工厂已于2011年被联合国教科文组织列入世界文化遗产名录。 GreCon是世界领先的火花探测及熄灭系统以及质量检测控制系统的制造商。主要有用于板材行业的在线及实验室质量检测系统，例如人造板层压板表面质量监控系统SUPERSCAN检查生产线上每块板的表面图案，所生成的数据报告能详细地反映上游生产过程的情况，该系统可以对整个生产线进行优化；用于板材、家具、食品、烟草、汽车和化工等产生粉尘且易燃易爆行业的火花探测熄灭系统，可监测通过机械或气力输送方式输送物料或粉尘到料仓或除尘装置过程中的点燃源（火灾发生的燃烧源），并立即采取细小水雾对其进行熄灭，从而保证生产过程不中断，有效防止除尘器、料仓和干燥机等发生火灾和爆炸事故，保障现场生产的的安全性和连续性，避免机器损毁、人身伤亡和财产损失。     

单板密度β射线检测法的研究

单板是制造层积材、胶合板等人造板材的基础材料,其密度对人造板材的机械、物理性能影响很大.对单板密度进行快速无损检测具有较高的实用价值.本文在分析国内外木材密度检测现状的基础上,提出了一种以计算机为核心的可以在线、无损检测单板密度的β射线检测法,并研究了系统的实现原理.     

“专注”,细分领域赢取成功的要素——访德国EWS公司首席代表Hans Peter Kleinschmidt先生

问:请简单介绍EWS公司的基本情况. Hans:EWS公司专注于木质人造板行业各个测量系统的研发和设备制造.可以提供刨花板、MDF、0SB、胶合板等各种板材生产线的质量控制系统,包括火花探测与熄除系统、在线含水率测量、在线密度测量、非金属的质量测量、在线厚度测量等.这些测量系统可以帮助用户节省木料消耗,减少耗胶量,从而实现降低成本.当前这个话题越来越重要,因为木材原料、能源等价格持续攀升,所以这些部分占产品总成本的比例亦将越来越高.     

人造板厚度在线监测系统的研究

基于板厚偏差在线监测这一问题展开研究，采用智能仪器的设计方法和手段，进行人造板厚度在线监测系统的研究设计。通过对人造板板厚偏差控制要求的分析，确定了以超声波测试技术为基础、以计算机技术为核心的人造板厚度在线监测系统设计方案。     

人造板热压应力研究

在不同的制板工艺条件下压制纤维板和刨花板,并在线记录热压过程中的油压力.通过比较分析不同板材密度和厚度、板坯含水率及热压温度时,试板在热压过程中的油压力-时间曲线,总结人造板在热压过程中热压应力的变化规律.     

人造板在线测量技术和火灾防护系统

在欧洲,除了一些工业化国家之外,由于经济的萧条冲击着建筑业和家具业,人造板——碎粒板(即刨花板)和纤维板(本文指中密度纤维板)工业的经济形势并不理想。在国内,由于投资的局部过热,已经引起资源类原材料和相关人力资源的供应短缺,导致人造板生产厂家都面临成本上升的问题。所有板材生产制造厂被迫生产高附加值的材料,并尽可能降低能耗。可喜的是现代电子测量技术提供了各种各样先进的在线的、或实验室的检测仪器,使得节省原料、降低能耗并提高产量质量成为可能。1.在线测量系统在生产过程中运用在线测量系统是很必要的。虽然实验室中测量…     

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.     

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.     

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.     

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.     

Biogeochemical impacts of clearfelling and reforestation on blanket-peatland streams: II. major ions and dissolved organic carbon

Streams and drains in blanket-peatland forest in western Ireland were sampled weekly over 5 years, 1996–2000, using continuous, depth-proportional passive sampling. Analysis was for pH, alkalinity by Gran titration, anions by IC, metals by ICP, aluminium speciation by loaded-resin exchange, and dissolved organic carbon (DOC) by absorbance at 320 nm.

Effects of felling are identified graphically from two forest drains whose catchments (both about 1 ha) were clearfelled, and partial clearfelling of one larger catchment (somewhat over 1 km²), in summer 1999. Calcium concentrations and alkalinity were increased in the drain- and streamwater from the felled areas. The pH was increased in drains, while in the larger stream, pH range decreased while the mean increased. Phosphorus increased markedly with clearfell, in the absence of recent fertilising, and also increased with fertilising; these results are reported in an accompanying paper. Ammonium-nitrogen concentrations were increased in the two drains with felling, and temporarily decreased in the larger stream. Nitrate increased in some cases. Potassium and manganese concentrations also increased. Concentrations of DOC and organic monomeric aluminium increased gradually, subject to a continuing strong annual cycle. There were no clearfelling effects on concentrations of solphate, suspended solids or inorganic monomeric aluminium. In the two drains (fully clearfelled), concentrations of sodium, chloride and magnesium, and conductivity, were all reduced after felling. Fertilising effects other than for phosphorus were indistinct.

Effects of the combined clearfell–reforestation treatment were testable statistically, using randomised intervention analysis, between two larger streams (1 km²) as a treatment–control comparison. There were statistically significant positive responses in streamwater concentrations of nitrate, potassium, calcium, DOC and aluminium fractions. The implications for management practice depend on whether the loss of nutrients is sustainable for future crop productivity, and whether critical limits and loads of receiving ecosystems are exceeded.     

Effect of Drought on Growth and Mortality of Actively Growing Norway Spruce Container Seedlings Planted in Summer

Survival, root egress and height growth of 13-month-old actively growing Norway spruce ( Picea abies (L.) Karst.) container seedlings exposed to preplanting drying treatments (0, 4, and 8 days) and postplanting drought periods (1, 2, 3, and 4 weeks) were studied in the field between 5 July and 18 August 1999. The mortality of seedlings increased and the height growth and root egress decreased throughout the postplanting drought period. Postplanting performance was also affected by preplanting drying treatments. The results indicate that no risk of excessive mortality and growth restrictions occurs when actively growing seedlings are planted in summer, provided that seedlings are well watered before planting and the drought period does not exceed 3 weeks.     

Rehabilitation of diseased cacao fields in Peru through shade regulation and timing of biocontrol measures

The objective of this case study was to test the effectiveness of biocontrol for the rehabilitation of abandoned, diseased (moniliasis, witches' broom and black pod) cocoa and to develop testable hypotheses regarding the effect of shade and biocontrol timing. Three trial fields differed in their shade regimes. Biocontrol was administered starting either at flowering or pod filling. Disease incidence and yield were compared with cultural control alone. Biocontrol reduced moniliasis from 49% to 25%, independent of the shading regime and application time. Witches' broom was most severe without shade and unaffected by biocontrol. No significant effects on black pod were observed. Although biocontrol increased percentage healthy fruit independent of shading and timing, only the shaded plot with biocontrol from flowering onwards responded with increased yield. Our hypothesis is: 'In the rehabilitation of abandoned cacao, only fields under sustainable shade management and early onset of biocontrol can realise their production potential.' This revised version was published online in June 2006 with corrections to the Cover Date.     

qPCR quantification of Ophiognomonia clavigignenti‐juglandacearum from infected butternut trees under different release treatments

The use of a molecular assay for quantifying conidia of Ophiognomonia clavigignenti‐juglandacearum, the fungal pathogen responsible of butternut canker, was investigated. Purified DNA from conidia collected on glass fibre filters of a passive rain collectors was quantified using a TaqMan real‐time quantitative polymerase chain reaction (qPCR) assay. The qPCR assay could specifically discriminate the target species from all other North American known species of Ophiognomonia, and it was sensitive enough to repeatedly detect one conidium. A linear relationship between numbers of conidia and qPCR C_t values was determined, and used to assess the sporulation of the pathogen under trees that were released to promote their vigour. In total, 977 samples of field‐captured conidia from 49 trees, at two locations, and from two successive growing seasons were analysed. No significant difference of sporulation was observed under control and release treatments. However, our results demonstrated that qPCR assay was reliable for detecting and quantifying O. clavigignenti‐juglandacearum from environmental samples, which will be useful to assess further control methods for this disease.     

The potential of alley cropping in improvement of cultivation systems in the high rainfall areas of Zambia I. Chitemene and Fundikila

Three trials investigating the potential of alley cropping to improve the traditional systems of cultivation, chitemene and fundikila, in the Northern Province of Zambia are described. Flemingia congesta, Tephrosia vogelii, and Sesbania sesban, were grown in association with finger millet, groundnut, cowpea, and maize in various traditional cropping sequences. The indigenous species Tephrosia vogelii and Sesbania sesban were not able to withstand repeated pruning and the long following dry season, and were replaced with Calliandra calothyrsus, and Cassia spectabilis.Over a four year period, there was no benefit by alley cropping with any of the tree species on crop yields, and yields in alley crop treatments even dropped significantly below the control treatments in the fourth year, casting doubt on the potential of alley cropping for sustainable production. There was also no consistent effect on soil chemical characteristics in any of the trials. It was suggested that this lack of beneficial response to alley cropping was due to low tree biomass production low quality of prunings, and an inappropriate cropping sequence. There was no evidence that alley cropping contributed to enhanced nutrient recycling, despite substantial localised pools of soil nutrients, particularly in the chitemene, with which recycling could potentially occur.     

Toxicity of biocide GCSC-BtA on arthropod pests under different temperature conditions

The present research dealt with the toxicity of GCSC-BtA (Germany–China Scientific Cooperation-Bacillus thuringiensis-Abamectin), a new type biocide developed by conjugating a toxin from Bacillus thuringiensis (B.t.) with Abamectin from Streptomyces avermitilis, on arthropod pests under different temperature conditions. The results showed that GCSC-BtA possessed higher toxicity than B.t. crystal, Abamectin or Cypermethrin, with pest mortalities of 97.9, 93.7, 96.4, 82.3 and 96.7% for Tetranychus cinnabarinus (Boisd.) (Acari, Tetranychidae), Frankliniella occidentalis Pergande (Thys., Thripidae), Aphis fabae Scopoli (Hom., Aphididae), Plutella xylostella (L.) (Lep., Plutellidae) and Cameraria ohridella Deschka et Dimić (Lep., Gracillariidae), respectively. Toxicities of GCSC-BtA to T. cinnabarinus and P. xylostella decreased significantly at the older developmental stage with an exception that egg stage had the highest tolerance, in which LC₅₀s of GCSC-BtA were 0.0001, 0.0019 and 0.0708 mg/ml for nymph, adult and egg of T. cinnabarinus, and that 0.0399, 0.2035 and 0.9033 mg/ml for the 2nd instar larvae, 4th instar larvae and egg of P. xylostella, respectively. Also, the biocide was more effective to the lower stage of A. fabae than the higher one with LC₅₀s of 0.0023, 0.0086 and 0.0171 mg/ml against 1st instar nymph, 3rd instar nymph and adult, respectively. In general, toxicity of the new type of biocide was positively related to temperature against all the tested pests, except against T. cinnabarinus, where it was almost similar at the three temperature conditions. GCSC-BtA displayed significantly lower toxicities at 15/20°C than 20/25°C or 25/30°C against F. occidentalis, A. fabae, P. xylostella and C. ohridella. However, no significant difference was found in the toxicities against F. occidentalis, A. fabae and C. ohridella above 20°C, whereas toxicity against P. xylostella increased as temperature raised. Therefore, to achieve higher efficacy in the field, application rate and time should be devised according to these factors.