最新刊期
期 1 ， 2022
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摘要：With the increasingly serious environmental pollution and health hazards caused by oil contaminated water, the development of high-efficiency, low-cost, and green oil/water separation materials has attracted more and more attention. As a sustainable, renewable, and biodegradable environment-friendly natural material, wood possesses many advantageous features such as multi-scale hierarchical structure, high anisotropy, abundant pore structure, and diverse tunability. Taking advantage of its hierarchical porous structure directly, wood can be deliberately tuned in terms of its chemical composition, pore structure, and surface wettability through the "top-down" strategy, which can provide new ideas and methods for the development of high-performance oil/water separation materials. In this review, based on the two main oil-water separation methods of filtration and adsorption, the strategies for constructing wood-derived porous filter membranes and oil-absorbing materials in recent years are introduced. The latest research progress is summarized in using these two kinds of wood-based functional materials for separating immiscible oil/water mixtures, oil-water emulsions, and high-viscosity crude oils on water surface. In addition, the existing problems in the research of the wood-based porous oil/water separation materials and the perspectives of the future research direction are also discussed.关键词：wood;pore structure;wettability;oil/water separation;filter membranes;oil-absorbing materials- 313
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发布时间：2022-03-08 -
摘要：Digital image processing technology is one of the most widely used technologies in the identification of wood defects, which has the advantages of accuracy, rapidity, nondestructive, and low cost. With extensive literature research, this paper expounds the present status of studies on the wood defect recognition based on the digital image technology. The image preprocessing, segmentation, feature extraction and selection, and the algorithm involved in image recognition and classification process, were analyzed. The principles, characteristics, and existing limitations of each method were summarized. The trends of future research were discussed. Further study is needed on automation and artificial intelligent of digital image processing technology.关键词：digital image;defect identification;wood defects;image processing technology- 148
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发布时间：2022-03-08 - 摘要：Melamine formaldehyde (MF) resin is widely used in adhesives, flame retardant coatings, outdoor plate protection, and other fields, which are benefit from its wear resistant, waterproof, and other properties. However, due to the high cross-linking density and short flexible chain, the MF resin shows brittle characteristics, which limits its application scope. In this paper, the research on toughening modification of MF resin were reviewed with two aspects of external toughening and internal toughening. The development trend was also analyzed, in order to provide theoretical guidance and reference for the synthesis process of melamine formaldehyde resin with high performances.关键词：melamine formaldehyde resin;paper impregnated thermosetting resins;toughening modification;mechanical property
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发布时间：2022-03-08 -
摘要：According to the morphology difference of the raw-materials (small-diameter logs and wide-and-thin veneer), the wood scrimbers were divided into two categories: the traditional wood scrimbers and the high-performance wood scrimbers. In this paper, the processing technologies were reviewed and discussed, and the bottleneck issues were analyzed. In view of the weak points of the key technologies for the high performance scrimbers, four suggestions were proposed, including optimization of the fine crush technology for the wood bundles, increasing automation of the processing equipment, developing green and multifunctional wood scrimbers, as well as building sound theoretical and technical systems.关键词：wood scrimber;small-diameter log;crushed veneers- 110
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发布时间：2022-03-08
REVIEWS
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摘要：In order to explore the whole plant logistics planning technology and method of customized furniture intelligent manufacturing, this paper summarizes the principle of workshop logistics development process and workshop process planning of furniture furnishing manufacturing by using the theory of group technology and enterprise field research. The application of group technology in customized furniture intelligent manufacturing process and the characteristics of group process technology are analyzed. It is concluded that group process technology is the foundation of the workshop logistics planning; the key technologies of logistics planning of customized furniture intelligent manufacturing plant based on group technology are analyzed including the production logistics organization of furniture production process, which is composed of production space organization and time organization, and the logistics system control of furniture production process, which is composed of the control form, control process, and control method. This review provides reference for traditional furniture enterprises to break through key technologies and improve production efficiency in the process of transformation and upgrading to intelligent manufacturing.关键词：furniture intelligent manufacturing;group technology;workshop logistics and planning- 68
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发布时间：2022-03-08
SPECIAL REPORTS
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摘要：In order to study the propagation characteristics and energy attenuation modes of different acoustic emission (AE) modes, a method for extracting surface shear waves and internal longitudinal waves of wood AE signals was proposed based on the wave theory. The AE signal energy attenuation model was established. First, according to the ASTM-E976-2015, the AE source was generated on the surface of the sawn timber of Pinus sylvestris var. mongolica Litv. by breaking the lead core, and the AE raw signals of the surface transverse wave and the internal longitudinal wave were collected at different positions with the sampling frequency of 500 kHz. Then, the wavelet analysis method was used to reconstruct the AE wave-form from the original signal; the propagation characteristics of the surface shear wave and the internal longitudinal wave of the wood AE signal were investigated. Finally, an exponential function fitting method was used to construct the energy attenuation model of surface shear waves and internal longitudinal waves. The results showed that the AE energy of both the surface transverse wave and the internal longitudinal wave exhibited a significant exponential decay law when propagating in the wood; there were big differences in frequency distribution and propagation rate. In the initial stage of propagation, the surface transverse wave was mainly distributed in the two middle and high frequency bands centered at 80.0 kHz and 113.3 kHz. As it propagated on the surface of the wood, the high-frequency signal quickly attenuated to the low-frequency signal. The internal longitudinal wave was always in a relatively low frequency band, and its average propagation velocity was about 4.6 times that of the surface transverse wave.关键词：acoustic emission;Pinus sylvestris var. mongolica Litv. sawn timber;surface transverse wave;internal longitudinal wave;wavelet analysis;energy attenuation model- 49
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发布时间：2022-03-08 -
摘要：The morphological parameters and tensile mechanical properties of single tracheids in different growth rings of Chinese fir (Cunninghamia lanceolate), Chinese lace-bark pine (Pinus bungeana), and Japanese larch (Larix kaempferi) were studied and compared. The results showed that the length, width, ratio of length to width, tensile strength, elongation at break, and the elastic modulus of the tracheids of the three species of softwood nearly increased with growth rings. The length and width of Chinese fir tracheids were the largest, and the mechanical properties of larch latewood from the ninth growth ring tracheids were the best among three species. Analysis of variance showed that the morphologies of tracheids of the third growth ring were significantly different from that of other growth rings (P<0.05) of Chinese fir and Chinese lace-bark pine. There were significant differences in tracheid tensile mechanical properties between the third growth ring and other growth rings of Chinese fir and larch (P<0.05), while there was no significant difference in that among all the growth rings of Chinese lace-bark pine. These data provided the important basis for the efficient utilization of plantation wood fiber and building lumber.关键词：softwood;single tracheid;tracheid morphology;stretch;mechanical properties- 76
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发布时间：2022-03-08 -
摘要：Cultivated Lyuqinan agarwood is vigorously planted in Huidong as an important economic forest value due to the easy-forming-resin varieties. The lack of knowledge of scientific identification and accurate quality classification index has hindered the development and expansion of its functional products. In this study, 22 batches of Lyuqinan were selected to study the appearance and structural characteristics, ethanol extract contents, and chemical composition. The results showed that the oil content was rich in the Lyuqinan samples of 10~18 month-old, and its ratios of ethanol extracts ranged from 21.45% to 53.12%, with an average value of 41.10%, which provided a basis for the quality grading of Lyuqinan. 2-(2-phenythyl) chromoketones were the main components in the ethanol extracts of Lyuqinan, accounting for 47.72%~99.29% of the total content of the ethanol extracts. They are important chemical components in Lyuqinan, and can be used as the identification basis of Lyuqinan.关键词：Huidong Lyuqinan agarwood;ethanol extract content;2-[2-(4-methoxy) phenethyl] chromone;2-(2-phenethyl) chromone- 61
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发布时间：2022-03-08 -
摘要：The Chuan-dou joints of traditional residential timber structures were studied in this research project. The bearing mechanism of joints were analyzed. Three sets of full-scale test specimens of the straight tenon-type joints of the Chuan-dou style timber structure were designed and produced: one set was as the control group, the second set was reinforced with nails, and the third set was reinforced with angle steels. Cyclic loading tests were conducted. The results showed that the failure mode of the straight tenon-type joint was mainly caused by the partial compressive plastic deformation perpendicular to the grain and the pull-out of tenon. All of the hysteretic curves were in the reverse "Z" shape, and showed distinct pinch phenomena. Compared with the control group, the load-bearing performance of reinforced joints were improved. The nail-reinforced joints improved the stiffness, energy dissipation, and the deformation capacity before the nails fell off. The angle-steel reinforced joints significantly improved the stiffness, energy dissipation, and the deformation capacity before the girder fractured.关键词：Chuan-dou style timber structure;straight tenon-type joints;reinforcement;seismic performance- 53
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发布时间：2022-03-08 -
摘要：The digital simulations for intact and failure conditions of common timber structure joints of tenon-mortise joints and bolted joints were conducted based on the piezoelectric sensing technology. Specifically, the horizontal movement, rotation, and defects of tenons were considered as the failure load cases for tenon-mortise joints, while the relaxation of pre-tightening force was considered as the failure load case for the bolted joints. Then the failure index, which is the sum of signal energy for different frequency bands decomposed based on wavelet packet analysis, was used to quantitatively evaluate the degree of damage severity. Finally, the experiment of bolted joints was implemented to verify the digitalsimulation results. Both of the digital and the experiment results indicate that the signal energy received by piezoelectric plates gradually decreases with the increase of damage severity. The piezoelectric sensing technology can efficiently detect the local damage at the timber joints, which provide a reference for the engineering practice.关键词：piezoelectric sensing technology;timber structure joints;damage detection;wavelet packet energy- 51
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发布时间：2022-03-08 -
摘要：This article studied the shear performance of structural components with three connection modes, including two self-tapping screws, beech dowels, and beech-self-tapping-screw composite dowels. The simple shear test was conducted with each specimen. The force-displacement curve was analyzed by the method of characteristic values. Seven parameters were obtained, including the maximum load, ultimate load, yield load, initial stiffness, ductility coefficient, energy consumption, and final displacement. The results showed: 1) The parameters of the components connected by self-tapping screws were better than those of beech dowels, except the initial stiffness. 2) Two peak values were found in the curves of the components connected by the beech-self-tapping-screw composite dowels. The first peak value was 2 kN higher than the maximum load of the components connected by the beech dowels. The second peak value was 0.7 kN higher than the maximum load of the components connected by the self-tapping screws. 3) The final displacement value of the components connected by the composite dowels was between the components connected by beech dowels and self-tapping screws. The energy consumption was similar to the self-tapping screws. The rest of parameters of the composite dowels were better than those of beech dowels and self-tapping screws. Based on the study, the composite dowels can combine the good characteristics of both the beech dowels and self-tapping screws.关键词：beech-self-tapping-screw composite dowel;self-tapping screw;beech dowel;single shear performance;analysis method of characteristic value- 72
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发布时间：2022-03-08
RESEARCH PAPERS
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摘要：The recovery rate of eight volatile organic compounds (VOCs), including Toluene, Vinylcyclohexene, p-Xylene, Styrene, 2-Ethylhexyl Alcohol, Naphthalene, 4-Phenylcyclohexene and n-Dodecane, was determined in the environmental test chamber by the liquid standard injection, continuous sampling and interval sampling, automatic thermal desorption (ATD) and gas chromatography/mass spectrometry (GC/MS) analysis, and integral area calculation. The comparison of the recovery rate of the two VOCs environmental test chambers showed that the recovery rate of small molecular compounds were consistent, ranging from 83% to 99%; however, there were significant differences in the recovery rate of large molecular compounds. It was recommended that it was urgent to develop the test method standards of VOCs for the test chamber recovery rate. The recovery rate of eight VOCs in the formaldehyde chamber was much lower than that in the environmental test chamber, especially for Naphthalene and 4-Phenylcyclohexene, for which the recovery rates were less than 11%. It was recommended to pay more attention to the impact of the formaldehyde chamber on the recovery rate of the VOCs when the formaldehyde chamber was modified for VOCs testing.关键词：environmental test chamber;recovery rate;volatile organic compounds (VOCs)- 59
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发布时间：2022-03-08 -
摘要：In order to investigate the effect of natural aging, the bamboo scrimber, which was placed outdoors in Qingdao for two years was selected to test for the physicochemical and combustion properties. The results showed that the thickness swelling and water absorption of aged bamboo scrimber increased by 88.32% and 35.62%, respectively. The residual rate of modulus of elasticity and modulus of rupture were 79.91% and 75.72%, respectively. The dimensional stability and mechanical strength of aged bamboo scrimber can still met the requirements of GB/T 40241—2021 "Outdoor Bamboo Scrimber". The ash and fixed carbon content of aged bamboo scrimber were increased by 1.64 times and 2.29% than that of controlled samples, while the volatile content was decreased by 3.13%. In addition, the hemicellulose and cellulose in the aged bamboo scrimber were seriously degraded. The combustion test results showed that the ignition time of aged bamboo scrimber was extended by 22 seconds; the peak heat-release rate and the total smoke-release content decreased 8.41% and 18.53% respectively, while the total energy of heat-release changed slightly.关键词：bamboo scrimber;natural aging;contact angle;mechanical strength;combustion performance- 78
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发布时间：2022-03-08
RESEARCH BRIEFING
- 摘要：Wood processing is a green and low-carbon industry, which consumes lower energy and has less impact in the environment pollution. The targets carbon dioxide (CO2) emission peaking and carbon neutrality will bring important opportunities for China's wood industry. In this paper, it is systematically analyzed of carbon stock in wood and wood products and CO2 emission reduction in timber structure buildings. Then, the challenges which China wood industry faces are also summarized. Finally, development paths are proposed with the aspects of wood supply, energy consumption structure, carbon measurement standard, CO2 emission assessment, green and low-carbon technology innovation, carbon storage time in wood and wood products, cultivation of talents, and promotion of public awareness.关键词：CO2 emission peaking;carbon neutrality;carbon emission;wood industry;wood and wood products;timber structure
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发布时间：2022-03-08
DISCUSSION ＆SUGGESTION
- Address：Box 29，Research Institute of Wood Industry, No. 1, Dongxiaofu, Haidian District, Beijing Postal code：100091
- Tel：010-62889419 Email：mckx@caf.ac.cn
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