最新刊期
卷 38 ， 期 2 ， 2024
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摘要：The cracking of timber members is one of the main damage in the timber structure of ancient buildings, which affects the safety performance of ancient buildings. To study the crack types and characteristics in timber members of ancient buildings, timber members from 8 ancient wooden structures in North China were evaluated through field investigation. The types, shapes, quantities, and sizes of cracks were recorded. The cracking of naturally-dried modern wood was monitored for a long time to obtain the long-term data. The results show that the cracking ratio in ancient building timber members is about 85%. According to the crack morphology and cracking causes, the cracks in timber members can be divided into dry-shrinkage cracks and stress cracks. The majority of cracks are dry-shrinkage cracks, which appeared away from the pith, and the proportion is 78.16%. The characteristics of drying-shrinkage cracks are mainly affected by the shape of timber members. The characteristics of cracks in both air-dried wood and ancient building wood are the same. After reaching equilibrium moisture content, the cracking characteristics rarely change.关键词：ancient wooden structures;cracked timber member;field investigation;type and characteristic- 12
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发布时间：2024-05-31
KEY SCIENTIFIC RESEARCH BASE OF HISTORICAL BUILDING WOOD
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摘要：The microstructure characteristics and composition of wood are important factors that affect elastic parameters. However, little research has been conducted on the impact of volume fraction changes in wood components. The Hofstetter continuum micromechanics model for wood was improved by introducing ash. The effect of changes in the component volume fraction of poplar wood on elastic parameters was discussed. The result shows that the improved Hofstetter model can accurately predict the longitudinal elastic modulus EL, with an absolute value of error of 13.71%. The elastic modulus and shear modulus of poplar increase significantly when the component volume fraction with high stiffness such as crystalline cellulose increases. When the volume fraction of polymer network or amorphous cellulose increases, the increase of Poisson’s ratio is significant. Changes in the volume fraction of lignin or hemicellulose have a small impact on all elastic parameters.关键词：poplar wood;improved Hofstetter model;continuous medium hypothesis;components;elastic parameter;changes in component volume fractions- 11
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发布时间：2024-05-31 -
摘要：To obtain three-dimensional structured carbon aerogels with excellent electrochemical performance, cobalt oxide/carbon (CoO/C) aerogel derived from ZIF-67/TOCNF was prepared by directional freeze-drying and one-step carbonization, using TEMPO oxidized nanocellulose (TOCNF) as the matrix, adding ZIF-67. Results from scanning electron microscope (SEM) showed that the CoO/C aerogels can keep their original structure of ZIF-67/TOCNF before carbonization; CoO derived from ZIF-67 can be uniformly loaded in the carbon skeleton structure, providing more reaction sites. XRD analysis indicated that the ZIF-67/TOCNF aerogel showed that the diffraction peak of a typical ZIF-67 crystal was close to pure ZIF-67; the diffraction peak attributed to TOCNF was suppressed. Co was obtained via the thermal decomposition of ZIF-67. Co/C composite materials with better crystallinity were obtained by high-temperature carbonization. The test results through Raman spectroscopy indicated that the CoO/C composite material has a high degree of graphitization. The electrochemical test and analysis showed that the double-layer capacitance of CoO/C electrode materials was closely related to their internal three-dimensional pore structure. Compared with other carbonization temperatures (500, 600, 800 ℃), when the carbonization temperature was 700 °C, the CoO/C-700 aerogel electrode material has the optimal electrochemical performance with a specific capacitance of up to 92 F/g (0.5 A/g) and exhibits desirable rate performance and cycle stability.关键词：TEMPO-oxidized nanocellulose;carbon aerogel;imidazolate metal organic framework;electrode material- 8
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发布时间：2024-05-31 -
摘要：Populus spp., Ulmus spp., and Styphnolobium spp. are the three hardwood species commonly used in ancient buildings in China. To provide a reference for the preservation and restoration of ancient wood buildings, this study evaluated the decay resistance and preservative treatability of three hardwood species. First the decay resistance of the Styphnolobium japonica, Ulmus pumila, and Populus ussuriensis was determined using the laboratory decay resistance test method, and then the preservative treatability of the wood was evaluated by the net retention and cross-sectional penetration of injected CuAz-4 preservative. The preservative-treated specimens were tested for decay resistance. Finally, the pore structure parameters were quantitatively characterized by mercury intrusion porosimetry, to analyze the relationship between the pore structures and their preservative treatability. The results showed that Populus ussuriensis was the easiest to treat, Ulmus pumila was next, and Styphnolobium japonica was the most difficult to treat. Among them, Styphnolobium japonica was a strong decay resistant species (Grade I), Ulmus pumila and Populus ussuriensis were slightly durable (Grade III) and not durable (Grade IV), respectively. Ulmus spp. and Populus spp. wood components in ancient buildings needed to be treated to improve decay resistance. After CuAz-4 preservative treatment the wood samples reached the strong decay resistant level. Analysis of the results for pore structure and preservative treatability showed that mesopores were difficult to be penetrated by CuAz-4 preservative, the larger the pore size distribution in the macroporous range, the higher the percentage, the higher the preservative treatability of the wood.关键词：commonly used hardwoods in ancient buildings;decay resistance;pore structure;copper azole preservative;preservative treatability- 17
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发布时间：2024-05-31 -
摘要：This paper presents a damage identification approach based on the difference in curvature of strain modes to identify the defects of the cross-section of wooden beams. First, modal analysis was performed to establish the finite element models of both intact and damaged wooden beams using ABAQUS. Next, the damage identification indicators of strain mode and strain mode curvature difference were used to locate and identify the damage of the wooden beams, and the damage degree of the wooden beams was estimated by fitting the relationship between strain mode curvature difference and damage degree. Lastly, the wooden beams test was used to confirm the validity of the indexes. The results reveal that: the strain mode damage identification index is unsatisfactory for damage localization of wooden beams; the strain mode curvature difference index has strong sensitivity and can properly identify different damage and degrees locations of wooden beams.关键词：wooden beams;strain modal curvature difference;damage identification- 7
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发布时间：2024-05-31 -
摘要：To well understand the carbon emission of bamboo houses, this paper presents a life-cycle carbon emission assessment on a two-story bamboo house built at Nanjing Forestry University. Emission-reduction strategies for different carbon emission phases were proposed. Moreover, the differences in carbon emission from typical bamboo, timber, and steel houses with identical dimensions were compared. The results showed that the operation phases emitted the most carbon in the life cycle of the bamboo house, accounting for 89.8% of the total. The carbon storage in the engineered bamboo products accounted for 8.8% of the total carbon emission. Bamboo and timber houses with various structural systems exhibited similar net carbon emissions in their life cycles. Due to high energy consumption and low efficiency in thermal insulation of steel, the carbon emissions of steel structures are 89.9% higher than the average carbon emissions of three types of bamboo or wood structures.关键词：bamboo house;life-cycle assessment;carbon emission;carbon storage;carbon emission reduction strategy- 7
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发布时间：2024-05-31 -
摘要：Surface roughness was one of the important factors to evaluate the surface quality and processing performance of wood materials. In this study, wood scrimber was prepared with Populus tomentosa veneer and phenolic resin using single-factor tests to investigate the effects of the compression ratios (50%, 55%, 59%) and resin contents (10%, 15%, 20%) on the dry and wet surface roughness of wood scrimber. The results showed that the effect of the compression ratio on dry and wet surface roughness was significant; the effect on dry surface roughness was greater than that on wet surface roughness. With the increase in compression ratio, the dry surface roughness of the wood scrimber decreased gradually, and the wet surface roughness increased gradually. The effect of the resin content on dry and wet surface roughness was significant; the effect on wet surface roughness was greater than that on dry surface roughness. With the increase of the resin content, both dry and wet surface roughness of wood scrimber decreased gradually. Compared with Populus tomentosa veneer, when the compression ratio was 59% and the resin content was 15%, the dry roughness parameters Ra and Rz of wood scrimber were reduced by 79.64% and 73.07%, respectively; the wet roughness parameters Ra and Rz were reduced by 62.85% and 50.00%, respectively. In the actual production process, the dry and wet surface roughness of the wood scrimber can be managed by controlling the compression ratio and resin content to meet the needs of different application scenarios.关键词：wood scrimber;dry surface roughness;wet surface roughness;Compression ratio;resin content- 7
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发布时间：2024-05-31 -
摘要：In this study, bamboo scrimber specimens with three densities (1.10, 1.20, 1.30 g/cm3) and five moisture contents (4%, 8%, 12%, 16%, 20%) were tested for tensile and compressive elastic modulus parallel to grain. The changes of tensile and compressive elastic modulus parallel to the grain of bamboo scrimber under different densities and moisture contents were analyzed. The results showed that the tensile and compressive elastic modulus parallel to the grain of bamboo scrimbers increased with the increase of density. When the moisture contents increase, the tensile and compressive elastic modulus parallel to the grain decrease and then become balanced eventually. Through experiment research and data fitting, a two-parameter coupling model of tensile and compressive elastic modulus of bamboo scrimber was proposed. Both the linear combination model and the ASTM combination model can well predict the theoretical values of tensile and compressive elastic modulus of bamboo scrimber with changes in density and moisture content. The maximum errors between the measured values and the predicted values of tensile and compressive elastic modulus parallel to grain were 5.28%, 8.20% for the linear combination model, and 8.91%, 8.67% for the ASTM combination model, respectively. The linear combination model is recommended due to its effective calculation process in practical applications.关键词：bamboo scrimber;tensile and compressive elastic modulus parallel to the grain;density;moisture content;model prediction- 8
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发布时间：2024-05-31
RESEARCH PAPERS
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摘要：In the process of intelligent transformation in China’s manufacturing industry, blockchain technology has attracted wide attention. This paper summarizes the theoretical basis, technology, and application status of blockchain technology, and explores its feasibility in the application of home intelligent manufacturing aiming to address existing problems in this field. The focus is on customized home product quality traceability management, intelligent management of production and manufacturing process, supply chain operation management, establishment and management of CPS platform, and other aspects where blockchain technology can aid in home smart manufacturing enterprises’ management innovation path. This aims to improve home smart manufacturing management capabilities and promote the effective integration of blockchain technology and home smart manufacturing, thereby advancing the transformation of home manufacturing to intelligent manufacturing.关键词：blockchain technology;home intelligent manufacturing;enterprise empowerment;innovation paths- 4
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发布时间：2024-05-31
DISCUSSION ＆SUGGESTION
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摘要：The National standard of GB/T 18103—2022 "Engineered wood flooring" was issued on 30st December 2022 and effective on 1st July 2023. This paper briefly introduces the revision procedures, principles, and changes in the content of the new standard version. This work aims to guide the standard interpretation and implementation of the terminologies and definitions, classifications, requirements, inspection methods, and inspection rules, as well as identification, packaging, transportation, and storage.关键词：engineered wood flooring;national standard;revision;physical and chemical performance requirements- 7
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发布时间：2024-05-31
DISCUSSION ON STANDARDS
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