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1.
研究山杨高得率浆（ＣＴＭＰ、ＡＰＭＰ）废水在实验室用活性污泥法连续处理的净化效果。结果表明：（１）两种废水用活性污泥法处理可得到良好的净化效果。ＣＴＭＰ废水在全部水力停留时间（ＨＲＴ＝１０～５６ｈ）内,ＣＯＤ负荷量在２１８～１２９ｋｇ／ｍ３·ｄ时,ＣＯＤｃｒ、ＢＯＤ５去除率分别为６５９％～８１０％（平均７４６％）和９５５％～９８１％（平均９６８％）;ＡＰＭＰ废水在ＨＲＴ为１０～４６ｈ,ＣＯＤ负荷量为３４７～１６１２ｋｇ／ｍ３·ｄ时,ＣＯＤｃｒ、ＢＯＤ５去除率分别为８４０％～８５６％（平均８４９％）和９８０％～９８９０％（平均９８６％）;（２）在试验采用的全部水力停留时间内,通过处理产生的污泥的ＳＶＩ（污泥指数）均低于１５０ｍＬ／ｇ,污泥的沉降性能良好,在整个试验中,未发现污泥膨胀现象;（３）活性污泥法操作管理简单、方便,对废水的适应性强 相似文献
2.
杨木单板连续式热压干燥的研究 总被引：3，自引：0，他引：3
本文以生长在苏北地区的美洲黑杨单板（名义厚度１．７ｍｍ）为试材,在连续式热压干燥机上进行了生产型试验研究,采用高温导热油为载热体,热板温度１９２℃,热板压力０．０９ＭＰａ（前段）至０．１８ＭＰａ（后段）。研究结果表明：采用高温连续式热压干燥的方式辅以适当的“呼吸”周期,可在２ｍｉｎ内将生材单板（初含水率１４９％）干至８％以下的终含水率。干单板基本平整、光滑,终含水率均匀,无撕裂。单板厚度干缩率平均５．３％,横纹干缩率４．９％。胶合强度平均０．８１２ＭＰａ略高于网带对流干燥的０．７７９ＭＰａ,结果说明此法干燥人工林场木单板是可行的。 相似文献
3.
杨木单板条层积材热压工艺的研究 总被引：1，自引：0，他引：1
本项研究以杨木单板条为原料，在试验室条件下，研究了单板条层积材（ＰＳＬ）的热压温度、热压时间、热压压力及板材密度与板材性能之间的关系，并进行了优化处理，得出最佳热压参数：温度Ｔ＝１４５℃，时间ｆ＝２０ｍｉｎ（板厚１５ｍｍ），板材密度Ｄ＝０．６０ｇ／ｃｍ￣３，压力Ｐ＝６．７６ＭＰａ。 相似文献
4.
柔性电热板加热摞式热压工艺的研究与实践 总被引：1，自引：1，他引：0
在单层大开档压机中，将数块特殊制作的柔性电加热板按一定方式直接置于成摞堆放的板坯中对板坯进行加热加压。板坯为多层胶合板或细木工板。几年的研究与实践证明：与目前通常的刚性压板热压相比，板坯压缩率较小（低于４％），能源消耗也较低，电耗为３０～５０ｋＷｈ／ｍ３。在单板含水率为１４％～１８％的条件下，仍然有十分可靠的胶合，胶合强度均大于１．２ＭＰａ。 相似文献
5.
美洲黑杨(Populus deltoides Marsh)×青杨(P.cathayana Rehd.)分子连锁图谱的构建 总被引：19，自引：3，他引：16
利用随机扩增ＤＮＡ多态性ＲＡＰＤ方法，在美洲黑杨（Ｐ．ｄｅｌｔｏｉｄｅｓＭａｒｓｈ）×青杨（Ｐ．ｃａｔｈａｙａｎａＲｅｈｄ．）３代谱系中分析分子标记，构建出第１张美洲黑杨×青杨分子连锁图谱。共从３００个１０ｍｅｒ随机引物中筛选出７９个适合引物，检测出可供构图的分离标记１８０个。该图谱由２０个连锁群，１１０个ＲＡＰＤ标记组成。总图距为覆盖基因组总长度的７０３５％，标记间的平均间距为１７２７ｃＭ．连锁群长度在３７１～１８９８，相应标记分别在３～１０。本图谱为杨树抗病、虫和其它性状基因定位提供了框架结构，为实现杨树分子遗传育种迈进了最重要的一步。 相似文献
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Effects of Repeated Cycles of Dehydration Rehydration on Drought Tolerance of Jack Pine and Black Spruce Seedlings 总被引：1，自引：0，他引：1
李吉跃 《中国林学(英文版)》1998,(2)
应用根系喷雾箱（ＲｏｏｔＭｉｓｔｉｎｇＣｈａｍｂｅｒ,ＲＭＣ）形成的５次干旱循环,通过ＰＶ曲线的水分参数研究了多重复干旱循环对１年生北美短叶松ＰｉｎｕｓｂａｎｋｓｉａｎａＬａｍｂ．和黑云杉Ｐｉｃｅａｍａｒｉａｎａ［Ｍｉｌ］Ｂ．Ｓ．Ｄ．苗木耐旱特性的影响．结果表明,生长在干旱沙地的深根性树种北美短叶松,其丧失膨压的相对含水量（８０７６％～８１４１％）和水势（（－１７４±０１０）ＭＰａ）都比较低,细胞弹性模量（５７３～６５２ＭＰａ）比较小,而束缚水含量（５２７２％～５４２６％）比较高,显示出它固有的强有力的忍耐脱水能力;但是在多重复干旱循环下它却不能进一步调节其渗透势和细胞弹性,而且其束缚水含量和吸水能力也有所下降．生长在湿润地区的浅根性树种黑云杉,虽然其丧失膨压的相对含水量（８３５３％～８５５０％）和水势（（－１６８±００３）ＭＰａ）比较高,细胞弹性模量（８６２～９６４ＭＰａ）比较大,束缚水含量（３６４４％～４６０５％）比较低,显示出较弱的耐旱能力,但是它在多重复干旱循环下却能提高其束缚水含量以改善原生质耐旱程度,降低细胞弹性以提高其吸水能力,调节其渗透势以保持较高的膨压．这表 相似文献
7.
用ＵＦ、ＭＵＦ胶制作三种松木胶合板，分别就单板厚度、涂胶量及抽提物含量对胶合性能的影响，松木与柳安混合树种组坯、特殊添加剂对改善胶合性能的作用进行了研究。结果表明：除了老挝松边材ＭＵＦ胶合板以外，１．５和２．０ｍｍ厚的单板胶合强度均达到或超过日本ＪＡＳ普通胶合板的要求。合板胶合强度随单板厚度增加而下降，在一定范围内增加涂胶量可以提高合板胶合强度，混合组坯及施加特殊添加剂具有改善松木单板胶合性能的作用。 相似文献
8.
杨农间作对农田生态环境的改善 总被引：4，自引：0，他引：4
本文根据５ａ（１９９３～１９９７年）人工和自动气象仪器的观测资料,对不同模式杨农间作田中的温、湿、风和蒸发等小气候因子的时空分布及其效应进行了较为详尽的分析。结果表明：杨农间作的防风效能为４５％～８７％,平均５７％;可降低日最高气温０３℃～３４℃,平均降低１３℃;降低地面日最高温度６０℃,最高可达１９５℃;提高日平均绝对湿度０９ｈＰａ～２４ｈＰａ,平均１４ｈＰａ;提高日平均相对湿度１％～１３％,平均５％;减少水分蒸发１７％～３６％,平均２５％;在干热风日可使相对湿度＜３０％的持续时间减少４５ｈ。因此,杨农间作具有明显的防风、降温、增湿和减少蒸发的作用,这对改善田间小气候和农业生态环境,促进农业的高产、稳产具有重要意义。 相似文献
9.
红宝石喜林芋试管苗在生长与分化过程中，以培养基的营养水平４／５ＭＳ，温度２８～３０℃，每日照光１０ｈ，光照度１５００ｌｘ为适宜，用手术刀片切割继代利于生长分化，以细胞分裂素（６－ＢＡ）２．５～３．５ｍｇ／Ｌ，生长素（ＮＡＡ）０．１５～０．２５ｍｇ／Ｌ，两者配比Ｖ（ＢＡ）∶Ｖ（ＮＡＡ）＝１２．５～１４∶１较为适宜。 相似文献
10.
美国黑莓是当今风靡欧美，近几年迅速发展的第３代新兴水果，原产北美，为蔷薇科黑莓属多年生藤本植物。果实多汁柔嫩、晶莹透亮、呈紫黑色，果卵园形（似草莓），含可溶性固形物１００％、总糖５０７％、有机酸１２％～３８％、Ｖｃ１１～１８ｍｇ／１００ｇ、Ｖ... 相似文献
11.
《Wood material science & engineering》2013,8(3):128-131
Abstract This study was carried out to determine the effect of knife wear, as measured in hours of use, on the finger-joint strength of silver fir wood (Abies alba), bonded with polyurethane (PU) and polyvinyl acetate (PVAc) adhesives. Wood samples were collected after 1, 32 and 64 h of knife wear. Results showed that as knife wear increased, bending strength or modulus of rupture (MOR) of the finger-jointed samples was reduced by 11.1% (PVAc) to 21.2% (PU) after 32 h of knife wear, and by 19.6% (PVAc) to 27.6% (PU) after 64 h of knife wear, whereas modulus of elasticity (MOE) of the finger-jointed samples was reduced by 10.5% (PVAc) to 12.5% (PU) after 32 h of knife wear, and by 11.7% (PVAc) to 10.0% (PU) after 64 h of knife wear. Tension strength of the finger-jointed samples was reduced by 2.1% (PVAc) to 1.5% (PU) after 32 h of knife wear, and by 5.4% (PVAc) to 16.0% (PU) after 64 h of knife wear. 相似文献
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Babatola Olufemi 《林业研究》2012,23(2):295-298
In an effort to find suitable wood from natural forest to meet the demand for veneer products, the yield and tensile strength of veneers produced from Brachystegia nigerica were investigated. Two trees of B. nigerica were separately selected from 10 different natural forest zones while two logs were obtained from each tree. The logs were debarked and steamed in a vat prior to rotary peeling and slicing for veneer production. The optimum steam temperature was determined by considering different temperatures: 50°C, 60°C, 70°C, 80°C and 90°C for 24 h. Thereafter, optimum steam time was determined at the optimum temperature by considering durations of 24, 48, 72 and 96 h. The average taper of 0.75 mm per 1.0 m length was recorded for B. nigerica, indicating that the logs were reasonably cylindrical; thereby its logs are good for the production of veneer. The yield ranged from 44% to 61% with an average of 52% of the log input. The tensile strength of the veneer was tested perpendicular to grain and both peeled and sliced veneers had the highest tensile strength between 70°C and 90°C, suggesting that softening of wood polymers, especially lignin, is between 70°C and 90°C. The optimum temperature and time for veneer production are 70°C and 48 h, respectively. Commercial production of veneer from B. nigerica is feasible based on the yield and mechanical properties of the obtained veneer, thereby encouraging the expansion of the scope ofits utilization. 相似文献
14.
The effect of compression and incision on wood veneer and plywood physical and mechanical properties
Maija Kymäläinen Akio Yamamoto Kasperi Sokka Lauri Rautkari 《Wood material science & engineering》2020,15(2):97-103
ABSTRACTDrying takes the largest share of energy in plywood production, and varying moisture content of veneers necessitates re-drying that often leads to over-dry veneers with deactivated surfaces, which may promote imperfect bonding. In order to decrease the drying time, reduce the need for re-drying of veneers, and improve the quality of plywood, birch and spruce veneers were subjected to pre-treatment by cold compression, incision, or a combination of the two. The effects of pre-treatment on the veneer and plywood quality were assessed by standard tests. Compression had a beneficial effect on water removal of the wettest veneers (spruce sapwood (SW) and birch), but some thickness reduction was observed in the veneers as well as the finished birch plywood. Compression led to thickness reduction of spruce veneers, but had no effect on SW plywood thickness likely due to higher viscoelasticity. Both compression and the combination of incising and compression levelled the moisture variation within the compressed stacks. Incision improved the modulus of elasticity of birch plywood, shear strength of SW plywood, and both bending and shear strengths of heartwood plywood. Higher surface pressure decreased the drying time of spruce SW in both plain compression and combined incision and compression pre-treatment. 相似文献
15.
High formaldehyde emission and poor water resistance are two main disadvantages of urea formaldehyde (UF) resin. For that reason, a novel polyvinyl acetate (PVAc) type emulsion curing agent was developed in this paper. PVAc type emulsions, including PVAc, the co-polymer of PVAc and N-hydroxymethyl acrylamide (PVAc–NMA), and the ternary co-polymer of PVAc, NMA, and urea (PVAc–NMA–urea), were the main components. Water, aluminum chloride, ammonium dihydrogen phosphate, polypropylene glycol, silicone oil, and urea were the other components. Under heating, aluminum chloride and ammonium dihydrogen phosphate often underwent thermal decomposition and hydrolysis in solution, produce free acid to cure UF resin, so the curing agent could enhance the curing rate, and then shorten the curing time. In this curing agent, ammonium dihydrogen phosphate and urea worked as formaldehyde removers and reacted with free formaldehyde in UF resin, thus the formaldehyde emission exuded from the plywood could be effectively limited and reduced. The bonding strength of plywood was not improved very much, especially the dry bonding strength, but the wet bonding strength was little enhanced for the active hydroxymethyl group contained in PVAc–NMA and PVAc–NMA–urea underwent a self-cross-linking reaction to improve the bonding strength and adhesion force to the bonded substrate. More importantly, the results from the industrial production experiments were shown to be very good. 相似文献
16.
The purpose of this study was to develop a cost-effective method to manufacture high-performance laminated veneer lumber (LVL) from mountain pine beetle (MPB)-affected veneers through partial resin impregnation and optimum board layup. Dry MPB-affected veneer sheets were segregated into two stress grades based on dynamic modulus of elasticity (MOE). A new phenol formaldehyde resin with a 30% solids content was formulated for resin impregnation. To reduce resin consumption, only veneer sheets used as outer layers were dipped in the resin for 5?min and then dried to manufacture 13-ply LVL. The bending properties, shear strength and dimensional stability of these LVL billets were examined and compared to those from the controls made from entirely untreated veneers. The results demonstrated that high-grade (E1) MPB-affected veneers had lower resin solids uptake than low-grade (E2) counterparts based on a 5?min dipping. Compared with the controls, the LVL billets made from resin-impregnated veneers for outer layers yielded increased surface hardness, significantly improved dimensional stability, shear strength and modulus of rupture on both edgewise and flatwise as well as better appearance with no cosmetic concerns. However, the improvement in LVL bending MOE was dependent on initial veneer stress grade. For high-grade (or density) E1 veneers, the use of impregnated veneers resulted in insignificant improvement in bending MOE. The optimum product layup was to place one ply of impregnated E1 grade veneer each for product face and back. By contrast, for low-grade (or density) E2 veneers, the use of impregnated veneers yielded a significantly higher flatwise bending MOE compared to the controls. The recommended product layup was the placement of two plies of impregnated E2 grade veneer sheets each for product face and back. 相似文献
17.
Compression control and its significance in the manufacture and effects on properties of poplar LVL 总被引：1，自引：0，他引：1
Summary In order to control the compression effectively, the main processing parameters for hot-pressing of poplar LVL were investigated in this study. Results from an orthogonal experiment show qualitatively that compression of poplar LVL is influenced by pressing pressure and moisture content of the veneers. High press pressure and veneer moisture content lead to high compression during hot pressing. It is shown that compression has significant effects on modulus of elasticity, modulus of rupture, specific gravity and thickness swelling of poplar LVL. Modulus of elasticity, modulus of rupture and specific gravity appear to be directly proportional to compression within the compression range of 5% to 20%. Horizontal shear strength results indicate that, due to inadequate contact, proper glue bond may not be achieved between veneers of LVL with low compression. Thickness swelling appears not sensitive to compression between the compression range of 4% to 10%.The authors wish to acknowledge the financial support from the Natural Sciences and Engineering Research Council of Canada to this study, which was carried out when the first author was a visiting scientist at Wood Science and Technology Centre, University of New Brunswick, Canada. The veneers and adhesive used in this study were provided by Temlam Inc., Ville-Marie, Quebec. Their contribution is gratefully acknowledged. 相似文献
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以磷酸二氢铵（MAP）溶液为阻燃剂,通过浸泡尾叶桉单板,研究了单板的载药量;以Ⅱ类胶合强度为指标,利用正交试验对常规胶合板生产工艺进行了优选。在此基础上,选取浸泡时间和最优生产工艺试制了阻燃桉树胶合板,并对其Ⅱ类胶合强度和燃烧性能进行了检测。结果表明：不同厚度尾叶桉单板的载药量随浸泡时间的延长呈现相似的增长规律;试验所得常规尾叶桉胶合板最优生产工艺为施胶量210 g.m-2、热压温度130℃、热压时间8 min,该条件下胶合板的Ⅱ类胶合强度达到了2.01 MPa;单板浸泡8h后,单板平均载药量为32.05 kg.m-3,所制得阻燃胶合板氧指数提高了13.9%,炭化长度减少了8.3 mm（26.2%）,阻燃性能明显提高,而胶合强度也达到了Ⅱ类胶合板的国家标准。研究初步证明利用常规桉树胶合板生产工艺生产阻燃桉树胶合板是可行的。 相似文献
20.
人工林杨木的用途选择——实木或单板层积材 总被引：9，自引：0，他引：9
实木材性对单板层积材强度的贡献率可衡量单板层积材强度中源自实木材性的份额,是人工林杨木单项用途选择的基础。本文以３个无性系实体杨木和由３种不同厚度杨木单板分别组配的单板层积材为对象,以由贡献率引出的实木与单板层积材的份率差值为依据,研究得出人工林杨木的最终用途选择。结果表明：６９杨、７２杨和６３杨３个无性系杨木的平均份率差值分别为５７％、－１５％、－２９％,说明６９杨宜用作实木,７２杨和６３杨宜用作单板层积材;杨木用作不同组配结构的单板层积材时,实木与３５６５ｍｍ、２６１４ｍｍ、１５４５ｍｍ３种厚度单板组配的单板层积材的平均份率差值分别为４３％、－１３％和－４３％,说明实木与较厚的３５６５ｍｍ单板组配的单板层积材相比,杨木宜用作实木,与较薄的２６１４ｍｍ和１５４５ｍｍ单板组配的单板层积材相比,杨木宜用作单板层积材。不同荷载作用的结果下用途选择结果显示,在抗剪强度、弹性模量和冲击韧性３项性能上的份率差值为正,此时杨木宜用作实木;在抗弯强度、抗压强度和硬度３项性能上的份率差值为负,此时杨木则宜用作单板层积材。 相似文献