最新刊期
卷 38 ， 期 3 ， 2024
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摘要：Epoxy resin is commonly used for repairing and reinforcing of ancient building timber members. To ensure its scientific and rational application, a performance evaluation model for epoxy resin was established based on multi-criteria decision theory. The evaluation index of the epoxy resin set was determined based on the requirements and relevant standards for repairing and reinforcing wooden components in ancient architecture. The entropy weight method and the analytic hierarchy process were used to obtain each property index's objective weight and subjective weight respectively. The subjective and objective weights were used to weight each property index. Combined with the composite weight, the optimal order method and the TOPSIS (technique for order preference similar to an ideal solution) were used to construct two comprehensive evaluation models. Validation experiments were conducted to evaluate the performance of ten groups of epoxy resins. The results show that the composite weighted TOPSIS comprehensive evaluation model is both more comprehensive and objective, making it better suited for the evaluating epoxy resin comprehensively. This model can serve as a reference method for selecting epoxy resin for repairing and reinforcing ancient buildings.关键词：repairing and reinforcing ancient building timber member;epoxy resin;comprehensive evaluation method;technique for order preference similar to an ideal solution （TOPSIS）178|204|0更新时间：2025-05-29
KEY SCIENTIFIC RESEARCH BASE OF HISTORICAL BUILDING WOOD
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摘要：Wood sandwich compression is an advanced technology of compressing wood layers through controlling the position, thickness, and the number of the compressed layers to achieve mechanical property enhancement. By regulating the distribution of temperature and moisture in Chinese fir wood under the desired pressure, the positions and thickness of compressed layers were managed in this study. Furthermore, density distribution in the compressed Chinese fir wood was analyzed to investigate the feasibility of sandwich compression technology to plantation Chinese fir wood and to clearly understand the formation mechanism. The results indicated that when the preheating time ranged from 0.5 to 30 minutes, Chinese fir wood was sandwich compressed with various positions of compressed layers. As the preheating time extended, compressed layers moved from wood surfaces into center and the compressed layer's density exceeded 0.583 g/cm³. By changing the compressing rate and thickness of wood specimen, four types of surface compressed wood with a compression layer thicknesses' range between 3.00~8.07 mm were obtained. The average density of the compressed layer was 28.7% higher than that of the original wood. Combining the technologies for surface compression and centre compression, three distinct compressed layers were formed in the sandwich compressed wood. It was also found that the boundary between the compressed layers and uncompressed layers appeared in the earlywood and the boundary between earlywood and latewood, regardless that compression occurred on wood surface or inside wood. Remarkably, the earlywood cells in the compressed layer underwent significant distortion, leading to the disappearance of almost all cell cavities. On the other hand, latewood cells exhibited little deformation or even remained intact. Based on the density profiles and the calculated characteristic values before and after compression, the maximum density of the compressed earlywood was 210.6% higher than that of the corresponding uncompressed earlywood.关键词：Chinese fir plantation;sandwich compression;density distribution;position of compressed layers;thickness of compressed layers;earlywood and latewood;cell wall distortion188|125|0更新时间：2025-05-29 -
摘要：The vascular bundle is an important component whose microscopic characteristics and distribution affect coconut wood’s physical and mechanical properties. In order to evaluate the variation of vascular bundles and their effect on the physical and mechanical properties at various tree positions, 40-year-old coconut wood from Hainan province of China was tested. The distribution density, diameter, cross-section area, and total area percentage of vascular bundles were evaluated in height and radial directions, while the total area percentage of vascular bundle effect on density and mechanical properties were also investigated. The results showed that there are no significant differences in the morphological characteristics of vascular bundles and physical and mechanical performance among different trees, except in total area proportion of vascular bundles and MOR. In the radial direction, the distribution density, diameter, cross-section area, and total area percentage of vascular bundles gradually increase from the center to the periphery, showing a significant positive linear correlation along the radial position. The density and mechanical properties of coconut wood gradually increase from the center to the periphery, with a high positive linear correlation with the total area proportion of the vascular bundles. In the height direction (from bottom to top), the diameter and cross-section area of the vascular bundles gradually decreased, and the distribution density and total area percentage of the vascular bundles first increased and then decreased, with an overall strong negative linear correlation. In general, the density and mechanical properties of coconut wood increase as the area percentage of vascular bundles increase. A model of the physical and mechanical properties of coconut wood is developed based on the proportion index of vascular bundle area. The predicted results from the model provide a basis for sawing and grading coconut wood.关键词：coconut wood;vascular bundle;morphological characteristics;physical and mechanical properties108|82|0更新时间：2025-05-29 -
摘要：In this study, Chinese fir wood was impregnated with melamine-urea-formaldehyde (MUF) resin solution with an 8% ratio, and then the quasi-static large deformation compression tests were conducted to investigate its compressive failure modes, mechanical properties, and energy absorption performance. The results were as follows: The weight percent gain of the modified wood reached 33.22%, and its anti-swelling efficiency attained 64.44%, indicating improved dimensional stability. The modification had no significant effect on the wood compression failure modes. The longitudinal failure mainly involved fiber buckling and tearing, the radial failure mainly involved layer-by-layer crushing of earlywood and latewood, while the tangential compressed wood was mostly matchstick damage. The compressive modulus of elasticity and crushing strength in modified specimen increased. Their plane stresses risen greatly in the transverse compression but decreased slightly in the longitudinal compression, and their densification strains decreased. The difference in compressive mechanical properties between longitudinal and transverse directions was reduced. The energy absorption per unit volume in the radial and tangential directions of the modified wood increased by 30% and 17% respectively, owever, both the longitudinal compression energy absorption and the maximum energy absorption efficiency decreased significantly. Low mass fraction MUF resin modification can significantly improve the dimensional stability of Chinese fir wood and reduce its energy absorption differences between longitudinal and transverse compression.关键词：Chinese fir wood;melamine-urea-formaldehyde resin (MUF);quasi-static large deformation compression;failure modes;energy absorption properties173|171|0更新时间：2025-05-29 -
摘要：This study investigated the feasibility of using wood-plastic composites (WPCs) for load-bearing columns in low-density prefabricated houses. Co-extruded WPC hollow columns were evaluated through material property and axial compression tests. The effects of wall thickness, aspect ratio, and the thickness of embedded thin-walled steel tubes on the ultimate load-bearing capacity, deformability, and failure modes of WPC hollow columns were analyzed using ABAQUS software. The simulation results were highly consistent with the experimental test data, validating the effectiveness of the modeling approach. The experiment’s results showed that the primary failure mode of the columns was localized buckling and a significant elastoplastic behavior was observed in the later stages of compression. Finite element analysis indicated that an increase in wall thickness improved both the initial stiffness and the ultimate load-bearing capacity of the columns, with an 8 mm thickness improvement to be the most cost-effective in terms of cost, weight, and load-bearing capacity. As the aspect ratio increased, there was a gradual decrease in both the load-bearing capacity and stiffness of the columns, with a shift in failure mode from strength failure to buckling. Integrating a 3 mm thin-walled steel tube significantly enhances the load-bearing capacity and ductility of the hybrid columns, making the mechanical properties suitable for use as compressive load-bearing members in building structures.关键词：wood-plastic composite hollow columns;axial compressive property;finite element analysis;load-displacement relationship;ultimate load capacity155|164|0更新时间：2025-05-29 -
摘要：Photosensitive resin is an important raw material for photocuring 3D printing, which most of them are derived from high-cost non-renewable petrochemical resources. Therefore, there is an urgent need to develop novel green and low-cost photosensitive resin materials and optimize their 3D printing process. In this study, moso bamboo (Phyllostachys edulis) pyrolytic oil was used as the raw material to synthesize bio-oil polyurethane acrylate (BPUA) photosensitive resin. The parameters of the BPUA resin for photocuring 3D printing were optimized as following: the exposure time of 5 seconds, the thickness of the sliced layer of 0.05 mm, and the number of the bottom layer of seven. Under this condition, good mechanical properties were achieved with a tensile strength of 21.94 MPa, a fracture strength of 17.55%, and a hardness of 76.6 HD. Several planar and three-dimensional structural models were successfully printed with the optimized process parameters showing high dimensional accuracy and good surface quality as indicated by the microscopic and chemical analyses.关键词：photocuring 3D printing;moso bamboo pyrolytic oil;photosensitive resin;polyurethane acrylate;process parameters115|111|0更新时间：2025-05-29 -
摘要：This study investigated the effect of density variations on the performance of rice husk/polyvinyl chloride (PVC) foamed composite materials (RHPC) to address the challenges of high density and poor dimensional stability in traditional un-foamed wood plastic composites (WPCs). Three distinct densities of RHPC were fabricated using rice husk and PVC. The results revealed that as the foaming degree increases, the density and the uniformity of the cell pores decrease respectively. Notably, the coefficient of linear thermal expansion (CLTE) and water absorption expansion rate of the RHPC progressively increased from RHPC-I to RHPC-III, exhibiting anisotropy in dimensional changes across length, width, and thickness directions. Further analysis indicated that humidity exerted a greater effect on the dimensional stability of RHPC than the temperature. Additionally, a decrement in the bending strength, bending modulus, and creep resistance was observed from RHPC-I to RHPC-III. However, RHPC-II exhibited the highest impact strength of 14.3 kJ/m2 and specific impact strength of 19.9 (kJ·m-2)/(g·cm-3), which was attributed to its uniform cell structure. This research provides valuable insights for developing lightweight-high-strength WPCs and expanding its potential applications.关键词：rice husk/polyvinyl chloride foamed composites (RHPC);foaming;mechanical properties;dimensional stability;creep128|129|0更新时间：2025-05-29 -
摘要：In order to enhance the value of lignin in oil-tea camellia fruit shells and achieve the high-value utilization of waste resources from Camellia processing. Under the conditions of optimizing the process: oil bath temperature of 160 ℃, treatment time of 6 hours, solid-liquid mass ratio of Camellia oleifera shell to deep eutectic solvent (DES) of 1∶10, and mass ratio of DES to H2O of 10∶1, four types of DES were used to treat abandoned Camellia oleifera shell, including choline chloride urea (ChCl-U), choline chloride urea H2O (ChCl-U-H), choline chloride urea ethylenediamine (ChCl-U-E), and choline chloride anhydrous oxalic acid (ChCl-OA). The effects of DES on lignin in oil-tea camellia fruit shells were investigated. The extracted lignin structures were analyzed. The results showed that the extraction rate of lignin was the highest after ChCl-U-E treatment, reaching 84.40%. The proton (H+) dissociation from the hydrogen bond donor in DES promoted the cleavage of unstable ether bonds between lignin phenylpropane units, forming small molecular substances and introducing phenolic hydroxyl groups, methoxy groups, and hydroxymethyl groups. The extracted lignin has a lower molecular weight, reduced steric hindrance, and increased activity. The extracted lignin is mainly composed of guaiacyl propane units, with a small amount of p-hydroxyphenyl propane units. The basic unit structure is relatively intact. This study provides a theoretical basis for preparing lignin-based phenol-formaldehyde resins and other aromatic compounds.关键词：oil-tea camellia fruit shells;deep eutectic solvent;lignin;extraction rate127|944|0更新时间：2025-05-29 -
摘要：Wood density includes basic density, air-dry density, etc. The air-dry density (D12) measured at the moisture content of 12% is more commonly used, so it is necessary to convert wood air-dry density to basic density (Db). Currently, the models that use air-dry density to calculate basic density, include Reyes, Chave, Simpson, and Vieilledent models. However, these models do not offer completely consistent predictions. This study used data of wood basic density and air-dry density from Research Institute of Wood Industry, Chinese Academy of Forestry (CRIWI) and French Agricultural Research Centre for International Development (CIRAD) to evaluate the prediction precision difference among the models mentioned above. Firstly, a correlation model- between D12 and Db was established based on CRIWI wood density database. Then, the air-dry density at 12% moisture content of individual wood species from the CRIWI and the CIRAD wood density database was applied to the Reyes model, Chave model, Simpson model, Vieilledent model, and the newly fitted model respectively to predict basic densities of each wood species. Then the mean absolute value of the error (MAE) was calculated from the predicted and the measured value of the wood basic density . By comparing the MAE of different models, the results indicate that only the Reyes model can appropriately predict basic density corresponding to either the CRIWI or CIRAD wood density databases. For both the Simpson model and the newly fitted model, the accuracy in predicting basic density significantly decreases when the air-dry density at 12% moisture content exceeds 1.0 g/cm3.关键词：wood basic density;wood air-dry density;correlation model;moisture content124|126|0更新时间：2025-05-29
RESEARCH PAPERS
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摘要：The field of smart homes in China has developed to a certain stage, with qualitative research dominating previous studies and quantitative research being largely absent. Therefore, using the CiteSpace software, a visualization analysis was conducted on smart home-related literature collected from the China National Knowledge Infrastructure (CNKI) and Web of Science core databases from 2013 to 2023, aiming to provide insights and references for smart home research in China. The study found that among the contributing countries, the United States made the largest contribution to the field of smart homes. At the same time, research in China, although extensive, had limited influence. Regarding author and institution analysis, domestic core authors demonstrated a higher level of collaboration, whereas collaboration among institutions was relatively low. Regarding research hotspots, domestic and international research mainly focused on Internet of Things (IoT) technology, cloud computing technology, and remote control, with international research also delving into privacy-related studies. As for research trends, early domestic research emphasized remote control and digital homes, while international research emphasized smart grids, sensors, and feedback. In the current stages, domestic research shifted towards sensor technology and artificial intelligence interaction, while international research focused more on energy utilization and privacy protection.关键词：smart homes;core journal articles;data visualization;trend analysis;CiteSpace517|1507|0更新时间：2025-05-29
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