oalib

Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99

Submit

Any time

2019 ( 48 )

2018 ( 828 )

2017 ( 869 )

2016 ( 865 )

Custom range...

Search Results: 1 - 10 of 34159 matches for " 詹先旭 "
All listed articles are free for downloading (OA Articles)
Page 1 /34159
Display every page Item
单板接缝对LVL力学性能的影响
许斌,,沈文益,程涵
- , 2015, DOI: 10.13360/j.issn.1000-8101.2015.01.017
Abstract: 将LVL中的单板接缝分别配置在表芯层、同一垂直面上、错开的相邻层,并对所测得的力学性能进行分析,结果表明:除最外3层同位接缝外,其他接缝板材的3点弯曲和4点弯曲静曲强度和弹性模量都大于无接缝板A。同位接缝的水平剪切强度按接缝11,5,6,7和9层递增。表背3层接缝错开对板材的静曲强度提高幅度高于芯层5层接缝错开的影响; 弹性模量在表背3层随着接缝错开距离的增加而升高,随着芯层5层接缝错开距离的增加而减小。
Veneers of laminated veneer lumber(LVL)were joined by scarf joints. The positions of the joints were either the same in adjacent layers or not. Mechanical properties of the lumber were investigated. It was found that joined veneers improved the modulus of elasticity(MOE)and modulus of rupture(MOR)of the lumber except for samples with the same position joints in the outer 3 layers. For samples with the same position joints, the 9-layer joint arrangement exhibited the highest horizontal shear strength, followed by 7-layer, 6-layer, 5-layer and 11-layer arrangement. For samples where the joint positions were not the same, the MOR of the samples with joints in the 3 outer layers was higher than those with joints in the 5 core layers. In the 3 outer layers, the MOE increased with the increasing of the adjacent joints distance. However, in the 5 core layers, it decreased with the increasing of adjacent joints distance
木质人造板吸水过程中内部单元体尺寸及相对位置的变化
李万兆,,杨勇,梅长彤
- , 2018, DOI: 10.13360/j.Issn.2096-1359.2018.03.004
Abstract: 吸水易导致木质人造板物理力学性能的变化。为探讨木质人造板吸水后内部单元体尺寸及相对位置的变化,使用X射线断层扫描仪检测吸水前后4种中密度纤维板(MDF)、2种定向刨花板(OSB)和1种胶合板(PW)的内部单元体尺寸及相对位置的变化,分析了吸水导致人造板内部单元体尺寸及相对位置变化的原因,深入剖析了胶黏剂、添加剂和组坯方式对人造板结构稳定性的影响。结果表明,人造板吸水后尺寸增加主要集中在厚度方向。三聚氰胺改性脲醛树脂胶黏剂和石蜡添加剂,二苯基甲烷二异氰酸酯胶黏剂能有效保持MDF内部单元体间相对位置的稳定。吸水后,酚醛树脂胶黏剂所制OSB易发生胶层分离。PW的内部组成结构可更好地保持人造板的尺寸稳定性和结构完整。试验结果为优化人造板生产工艺和指导人造板的合理使用提供了理论依据。
Wood-based panels have been widely used as basic decorative products and construction materials for decades. They play an increasing important role due to the multiple advantages, such as raw material compatibility, ease of implementation, adaptability to continuous processing and standardization of the products. Physical properties of wood-based panels are prone to be influenced by water uptake, which limits the application field of wood-based panels. Generally speaking, the water uptake could lead to dimensional instability and decrease in mechanical strength of wood-based panels. Understanding the variation of internal unit during the water uptake process, therefore, is essential for optimizing the production and application of wood-based panels. In order to investigate the size and relative position of the internal unit changes induced from the water uptake, specimens prepared from four types of medium density fiberboard(MDF), two types of oriented strand board(OSB)and one type of plywood(PW)were scanned before and after the water uptake process by using an X-ray CT scanner. The reasons of size and relative position changes caused by the water uptake in wood-based panels were studied. The influence of glue, additives and the way of mattress on the structural changes of wood-based panels was discussed during the water uptake. The results showed that the X-ray CT scanning could timely visualize the 3D internal structure of wood-based panels. The dimensional increase in wood-based panels after the water uptake mainly occurred in the thickness direction. The application of melamine modified urea formaldehyde(MUF)resin, paraffin emulsion and methane-diisocyanate(MDI)resin could improve the stability of internal structure of the MDF. The glue line detachment in phenol-formaldehyde(PF)glue line was prone to occur in OSB after the water uptake. The way of mattress in the PW could better stabilize the dimension and internal structure of wood-based panels during the water uptake. The results obtained from this study can be used in optimizing the processing technology and application approaches of wood-based panels
三聚氰胺甲醛树脂薄木浸渍工艺及性能
汤正捷,,杨勇,闫文雯,徐信武
- , 2018, DOI: 10.13360/j.issn.2096-1359.2018.06.005
Abstract: 以水曲柳为薄木原料,三聚氰胺甲醛树脂(MF)为浸渍液体,研究了薄木的浸渍工艺,包括不同干燥温度、干燥时间、固化剂添加量以及耐磨剂种类和添加量; 通过树脂含量、挥发物含量和预固化度3个主要指标评价了不同浸渍工艺生产的浸渍薄木的性能,结合浸渍薄木贴面后的表面耐磨性能,对不同耐磨剂进行了比较。结果表明,当干燥时间一定时,浸渍薄木的挥发物含量随干燥温度的上升呈下降趋势,浸渍薄木的预固化度随着干燥温度的上升而增大。在一定的干燥温度和固化剂条件下,干燥时间越长,挥发物含量越低,预固化度越高。其他条件不变,固化剂施加量越大,浸渍薄木的挥发物含量越低,预固化度越高。使用氧化铝作为耐磨剂的效果优于铝粉,比纯MF浸渍的耐磨性能提高了3.8倍,虽然贴面后的耐磨性能比耐磨纸差,但达到了浸渍纸层压木质地板家用Ⅱ级标准。研究表明,参照浸渍纸工艺生产浸渍薄木是可行的,采用添加3‰固化剂、干燥温度120 ℃、干燥时间120 s和氧化铝为耐磨剂(添加量为35 g/m2)的工艺时,产品性能最优。
Overlaid with veneers is one of the commonly used surface decoration methods for wood-based panels, which can not only protect the substrate, but also increase the added value of the product. Compared with the impregnated paper overlay, it is usually necessary to carry out secondary treatment of painting after the veneer is overlaid. If the impregnated veneer is processed with the procedure of the impregnated paper, the advantages of the veneer decoration and the impregnated paper overlay can be combined. Impregnating process of thin veneers of manchurian ash(Fraxinus mandshurica)with melamine formaldehyde resin includes the variety of drying temperature, drying time, addition of different curing agents and amount of wear-resisting agent were investigated in this study. The properties of thin veneers with melamine formaldehyde resin were evaluated by the resin content, volatile content and pre-curing degree. Different wear-resistant agents were compared by surface abrasion resistance after overlaid the impregnated veneer. The results showed that the volatile content of thin veneers with melamine formaldehyde decreased with the increase of drying temperature, and the pre-curing degree increased with the increase of drying temperature, when the drying time remained constont. The volatile content of thin veneers with melamine formaldehyde decreased with the increase of drying time, and the pre-curing degree increased with the increase of drying time, when the drying temperature and addition of curing agent remained constont. With the increase of the amount of curing agent, the volatile content of thin veneers with melamine formaldehyde decreased and the pre-curing degree increased, when other conditions remained constont. The use of aluminum oxide as a wear-resistant agent was superior to the aluminum powder, which was 3.8 times than the pure MF impregnation. Although the wear resistance after overlaying impregnated veneer with aluminum oxide was worse than that of the wear-resistant paper, it reached the requirement of laminate flooring. The properties of thin veneers with the melamine formaldehyde resin were good,
阻尼涂饰意杨胶合板的表面性能
杨雪莲,徐信武,吕吉宁,
- , 2016, DOI: 10.13360/j.issn.2096-1359.2016.01.005
Abstract: 针对防滑防振型结构胶合板的开发,探索采用阻尼涂料对意杨胶合板进行表面涂饰处理,以构建新型木基阻尼结构体系。试验了自由型和约束型两种阻尼结构,全面分析了阻尼涂饰意杨胶合板的涂层附着力、涂层界面、摩擦系数、耐磨性、硬度和耐冲击等性能。研究结果表明:总体而言,阻尼涂饰能在确保良好界面结合的基础上,赋予胶合板优异的表面性能。阻尼涂料能有效渗透入意杨木材,形成紧密的结合界面。阻尼涂饰胶合板的表面防滑性能和耐磨性能均优于常规MF浸渍纸饰面板,表面布氏硬度和抗冲击性能优于意杨胶合板素板,其中布氏硬度达到44.02~51.97 MPa,冲击强度最高达到30.71 kJ/m2。综合考虑,建议采用自由型阻尼结构,阻尼涂料厚度控制在约1.5~2.0 mm。以上研究结果对于开发功能型胶合板新产品具有显著的参考价值。
In order to develop anti-slipping and vibration structural plywood, damping coating was applied to paint poplar plywood aiming to develop a new wood-based damping system. Two types of damping constructions known as freedom and constrained respectively were built. The surface properties of the coated plywood were tested in aspects of coating adhesion, interface, friction coefficient, wear resistance, hardness, and impact strength. The results showed that: damping coatings could be bonded to poplar plywood with strong adhesion and good surface properties. The damping coatings could penetrate poplar wood resulting in close interface and strong adhesion. The coated plywood had better surface anti-slipping and wear resisting performance than normal melamine formaldehyde(MF)resin impregnated paper, and had higher hardness(44.02-51.97 MPa)and anti-impact strength(up to 30.71 kJ/m2)than those of control poplar plywood. It is comprehensively suggested that freedom construction with 1.5-2.0 mm paint layer could be applied to make damping structural plywood. This research results may have valuable reference in developing and manufacturing functional plywood products
杨木真空镀膜处理后的表面特性 ??Symbol`@@
朱莉娜,黄河浪,吕亚会,毛润,安然,,王敏
- , 2016, DOI: 10.13360/j.issn.2096-1359.2016.01.008
Abstract: 通过在杨木表面沉积派拉伦薄膜来提高杨木的防水性能,研究中采用真空蒸发的镀膜方式将派拉伦薄膜沉积在杨木表面,通过扫描电镜、接触角测量仪等现代分析仪器研究经过镀膜处理后的杨木表面微观形貌变化和润湿性变化,并通过24 h浸水试验研究杨木的防水能力。处理工艺为:蒸发温度92~97 ℃,裂解温度680 ℃,沉积室真空度0.1 Pa,沉积室温度 25 ℃,蒸镀时间5 h。试验结果表明,派拉伦薄膜成功沉积在杨木表面,并可以形成较完整的膜层,但其在杨木横切面与纵切面表面的沉积状态有所不同; 镀膜处理后试件的接触角明显增大; 24 h吸水率以及24 h体积膨胀率下降幅度分别为35.9%和20.2%,14 d平衡处理后,杨木的24 h吸水率下降幅度为82.5%,24 h体积膨胀率下降幅度为56.3%。
Parylene film is mainly used for water treatment in the electronics industry, and is rarely used to treat wood surface. In this study, Parylene film with excellent waterproof and moisture-proof performance was introduced to improve the dimensional stability of poplar wood by means of vacuum deposition. The Parylene powder was evaporated at 92-97 ℃ and cracked at 680 ℃. The sanded samples to be coated were hung in a deposition chamber with a pressure and temperature of 0.1 Pa and 25 ℃, respectively, and the depositing time was 5 h. Scanning electron microscopy and contact angle measurement were applied to study the morphology and wettability of the coated samples. The waterproof performance of the samples was also studied by 24 h immersion experiment. The results showed that Parylene film was deposited on the wood surface successfully and formed a flat and smooth surface. However, significant deposition difference was found between transverse section and longitudinal section of the samples, which may attribute to the structural differences between the two sections. The deposited film exhibited poor continuity in transverse section. After the vacuum deposition, the contact angle of the samples increased; the 24 h water absorption and 24 h volume swelling dropped by 35.9% and 20.2%, respectively. After 14 days' conditioning, the 24 h water absorption of poplar wood decreased by 82.5%, and the 24 h volume swelling decreased by 56.3%. Based on the experimental results, Parylene film in wood surface coating was feasible to improve the waterproof performance, but further research is need to get better waterproof performance
船舶基本性能计算及绘图软件系统

重庆大学学报 , 1994,
Abstract: 采用3次参数样条插值和数值积方法,按精确公式用FORTRAN语言编程,得到9种船舶基本性能的计算结果。软件系统使用SCR文件与AutoCAD接口,自动绘制11种图形。
线性超应力模型在一维塑性波中的适用性

重庆大学学报 , 1984,
Abstract: 本文采用Malvern的线性超应力模型和Wood等人的特征线处理方法得到加载区一维塑性波的数值解并与Bell的实验进行了较为广泛的比较。所得结果与实验位符合较好。本文还证实了线性超应力模型可以予测实验条件下等应变区的存在,给出了铝和铜的速率灵敏系数K的建议值,讨论了铝的K值的普适性等问题。
广义规范矩阵的一些分解式
仕林,
安徽大学学报(自然科学版) , 2009,
Abstract:
实正定矩阵的若干判据
仕林,
安徽大学学报(自然科学版) , 2008,
Abstract:
Efficiency and mechanisms of simultaneous removal of algae and microcystins in source water
水源地藻类及藻毒素同时去除的效果及机制分析

,吕锡武
环境科学学报 , 2010,
Abstract: 利用组合载体对太湖梅梁湾水源地水体中藻类及藻毒素的同时去除试验表明:检测水源地水体中藻量、Chl-a、TMC的含量各为(31.67~78.27)×106个·L-1、32.58~102.67μg·L-1、1.79~11.97μg·L-1.在水力停留时间为7d、组合载体的密度为13.1%的条件下,组合载体AP对藻量的平均去除率达到了59.78%,对Chl-a的平均去除率达到了80.82%,对TMC-LR、TMC-RR、EMC-LR、EMC-RR的降解率最高能达到99.73%、97.10%、100%、75.44%.对其去除机制的研究表明,组合载体AP对总细菌的富集能力达到了8.3×1011~35.6×1011 cells·g-1,比湖水本底值中细菌的总数高出了8~9个数量级.对除藻及藻毒素过程中的优势菌种,经过培养、分离,考察其形态、生理生化特性,利用聚合酶链反应(PCR)、16SrRNA序列分析技术,经鉴定确认该优势菌株为假单胞菌属(Pseudomonas sp.)和芽孢杆菌(Bacillus sp.).组合载体AP上富集的大量微生物,它们的协同降解作用是去除藻及藻毒素的主要作用机制.
Page 1 /34159
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.