Forests

Research

19 pages, 8273 KiB

Open AccessArticle

An Efficient and Accurate Surface Defect Detection Method for Wood Based on Improved YOLOv8

by Rijun Wang, Fulong Liang, Bo Wang, Guanghao Zhang, Yesheng Chen and Xiangwei Mou

Forests 2024, 15(7), 1176; https://doi.org/10.3390/f15071176 - 6 Jul 2024

Viewed by 1442

Accurate detection of wood surface defects plays a pivotal role in enhancing wood grade sorting precision, maintaining high standards in wood processing quality, and safeguarding forest resources. This paper introduces an efficient and precise approach to detecting wood surface defects, building upon enhancements [...] Read more.

Accurate detection of wood surface defects plays a pivotal role in enhancing wood grade sorting precision, maintaining high standards in wood processing quality, and safeguarding forest resources. This paper introduces an efficient and precise approach to detecting wood surface defects, building upon enhancements to the YOLOv8 model, which demonstrates significant performance enhancements in handling multi-scale and small-target defects commonly found in wood. The proposed method incorporates the dilation-wise residual (DWR) module in the trunk and the deformable large kernel attention (DLKA) module in the neck of the YOLOv8 architecture to enhance the network’s capability in extracting and fusing multi-scale defective features. To further improve the detection accuracy of small-target defects, the model replaces all the detector heads of YOLOv8 with dynamic heads and adds an additional small-target dynamic detector head in the shallower layers. Additionally, to facilitate faster and more-efficient regression, the original complete intersection over union (CIoU) loss function of YOLOv8 is replaced with the IoU with minimum points distance (MPDIoU) loss function. Experimental results indicate that compared with the YOLOv8n baseline model, the proposed method improves the mean average precision (mAP) by 5.5%, with enhanced detection accuracy across all seven defect types tested. These findings suggest that the proposed model exhibits a superior ability to detect wood surface defects accurately. Full article

(This article belongs to the Special Issue Wood Quality and Wood Processing)

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16 pages, 4397 KiB

Open AccessArticle

BPN-YOLO: A Novel Method for Wood Defect Detection Based on YOLOv7

by Rijun Wang, Yesheng Chen, Fulong Liang, Bo Wang, Xiangwei Mou and Guanghao Zhang

Forests 2024, 15(7), 1096; https://doi.org/10.3390/f15071096 - 25 Jun 2024

Cited by 2 | Viewed by 1495

Abstract

The detection of wood defect is a crucial step in wood processing and manufacturing, determining the quality and reliability of wood products. To achieve accurate wood defect detection, a novel method named BPN-YOLO is proposed. The ordinary convolution in the ELAN module of [...] Read more.

The detection of wood defect is a crucial step in wood processing and manufacturing, determining the quality and reliability of wood products. To achieve accurate wood defect detection, a novel method named BPN-YOLO is proposed. The ordinary convolution in the ELAN module of the YOLOv7 backbone network is replaced with Pconv partial convolution, resulting in the P-ELAN module. Wood defect detection performance is improved by this modification while unnecessary redundant computations and memory accesses are reduced. Additionally, the Biformer attention mechanism is introduced to achieve more flexible computation allocation and content awareness. The IOU loss function is replaced with the NWD loss function, addressing the sensitivity of the IOU loss function to small defect location fluctuations. The BPN-YOLO model has been rigorously evaluated using an optimized wood defect dataset, and ablation and comparison experiments have been performed. The experimental results show that the mean average precision (mAP) of BPN-YOLO is improved by 7.4% relative to the original algorithm, which can better meet the need to accurately detecting surface defects on wood. Full article

(This article belongs to the Special Issue Wood Quality and Wood Processing)

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14 pages, 2693 KiB

Open AccessArticle

Effect of the Vacuum Impregnation Process on Water Absorption and Nail-Holding Power of Silica Sol-Modified Chinese Fir

by Mengxue Tao, Xia Liu and Wei Xu

Forests 2024, 15(2), 270; https://doi.org/10.3390/f15020270 - 30 Jan 2024

Cited by 3 | Viewed by 1017

Abstract

The application of fast-growing Chinese fir (Cunninghamia lanceolata) is limited due to low dimensional stability and weak mechanical strength. Silica sol can effectively improve fast-growing fir wood’s physical and mechanical properties. In order to clarify the influence of impregnation process parameters [...] Read more.

The application of fast-growing Chinese fir (Cunninghamia lanceolata) is limited due to low dimensional stability and weak mechanical strength. Silica sol can effectively improve fast-growing fir wood’s physical and mechanical properties. In order to clarify the influence of impregnation process parameters on the modification effect, the effect of the vacuum impregnation variants (e.g., pre-vacuum time, pre-vacuum pressure, pressurization time, and pressurization pressure) was discussed using the orthogonal test approach. The optimal modification process was determined by comparing the water absorption and nail-holding power under different modification processes. The range analysis and variance analysis methods were used to study the correlation between process factors and the performance of the modified wood. The results showed that the water absorption and nail-holding power of fast-growing fir wood were significantly improved via vacuum impregnating with silica sol. The optimum process parameters for water absorption and nail-holding power of fast-growing fir as the pre-vacuum time was 30 min, the pre-vacuum pressure was −0.08 MPa, the pressurization time was 3 h, and the pressurization pressure was 1.2 MPa. Full article

(This article belongs to the Special Issue Wood Quality and Wood Processing)

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13 pages, 4942 KiB

Open AccessArticle

Synergistic Effects of Heating Platens’ Temperature and Compression Ratio on the Periodic Hot-Press Drying of Chinese Fir Lumber

by Xiang Weng, Xingying Zhang, Chengjian Huang, Shipeng Wang and Junfeng Hou

Forests 2024, 15(1), 203; https://doi.org/10.3390/f15010203 - 19 Jan 2024

Viewed by 886

Abstract

The effects of periodic hot-press drying on drying behavior and mechanical damage to Chinese fir lumber were investigated by taking the heating platens’ temperature (T_P) and compression ratio (R_c) as experimental factors. The temperature and pressure inside [...] Read more.

The effects of periodic hot-press drying on drying behavior and mechanical damage to Chinese fir lumber were investigated by taking the heating platens’ temperature (T_P) and compression ratio (R_c) as experimental factors. The temperature and pressure inside lumber were analyzed during drying process. The results were as follows. The drying rate of lumber was significantly increased with increasing T_P and R_c. Scanning electron microscope (SEM) micrographs showed that bordered pit membranes, cross-field pits, middle lamella between adjacent cells, and tracheid walls were damaged after drying, and the damage became more severe with higher T_P and R_c. Detachments between ray parenchyma cells and tracheids were observed at 170 °C. Nitrogen-adsorption measurement results demonstrated that more cell wall pores in the 2.5~6.2 nm pore diameter range were generated at higher T_P, resulting in an enlarged specific surface area and pore volume of cell walls. These structural changes contributed to accelerating moisture migration and decreasing the drying time. Furthermore, fluctuating pressure inside lumber was the main driving force leading to moisture migration and cell tissue damage in lumber during drying. The influence of T_P on internal temperature (T_M) and pressure (P_M) was greater than R_c. With the increase in T_P from 130 to 170 °C at the R_c of 10%, the maximum T_M and P_M were increased by 30.90% and 39.84%, respectively. However, T_P should not be too high to prevent the formation of macro-cracks caused by high pressure, which may significantly affect wood’s mechanical properties. These results provide theoretical support for periodic hot-press drying processes’ improvement and high-value utilization of Chinese fir. Full article

(This article belongs to the Special Issue Wood Quality and Wood Processing)

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15 pages, 3985 KiB

Open AccessArticle

Characterization and Yield of Eucalyptus regnans F. Muell Logs for Lumber Production

by Carlos Rozas, Barbara Zapata, Fernando Muñoz, Virna Ortiz-Araya and Oswaldo Erazo

Forests 2023, 14(12), 2359; https://doi.org/10.3390/f14122359 - 30 Nov 2023

Viewed by 1244

Abstract

The yield of Eucalyptus regnans logs for lumber production was evaluated. Crack width and length at each log end were measured. Two log-cutting plans were used to obtain sawn lumber. The first plan (PA) considered logs with diameters varying from 28 to 40 [...] Read more.

The yield of Eucalyptus regnans logs for lumber production was evaluated. Crack width and length at each log end were measured. Two log-cutting plans were used to obtain sawn lumber. The first plan (PA) considered logs with diameters varying from 28 to 40 cm, and in the second plan (PB), the log diameters ranged from 42 to 56 cm (PB). Lumber yield was determined using two log volume methods: the Japanese Agricultural Standards (JAS) and Smalian’s equation. The deformations of E. regnans lumber were measured. The Australian and Chilean standards were used to classify sawn lumber. The results showed that logs had radial cracks at both log ends. Cracks were classified into two groups, considering the crack length. Regarding the lumber deformations, most boards exhibited level B bows and crooks in both cutting plans. Levels A and B twists were prevalent in PA, whereas in PB, level A significantly outnumbered level B. The lumber yield of E. regnans in PB was higher than in PA. The lumber yield determined by Smalian’s equation was higher than that determined by the JAS method. This research provides insight into the characterization of E. regnans for lumber production, highlighting its relevance in the forestry industry. Full article

(This article belongs to the Special Issue Wood Quality and Wood Processing)

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19 pages, 8308 KiB

Open AccessArticle

Combining Artificial Neural Network and Response Surface Methodology to Optimize the Drilling Operating Parameters of MDF Panels

by Bogdan Bedelean, Mihai Ispas and Sergiu Răcășan

Forests 2023, 14(11), 2254; https://doi.org/10.3390/f14112254 - 16 Nov 2023

Cited by 3 | Viewed by 1270

Abstract

Most of the parts of furniture made of medium density fiberboards (MDF) require at least one hole to be assembled. The drilling technological parameters influence the quality of holes. Factors such as tip angle of the drill bit, feed rate, type and diameter [...] Read more.

Most of the parts of furniture made of medium density fiberboards (MDF) require at least one hole to be assembled. The drilling technological parameters influence the quality of holes. Factors such as tip angle of the drill bit, feed rate, type and diameter of the drill bit, and spindle rotational speed could affect the drilling process. Therefore, the right choosing of drilling parameters is a mandatory condition to improve the drilling efficiency that is expressed through tool durability, cost, and quality of the drilling. Thus, in this work, we are proposed an approach that consists in combining two modelling techniques, which were successfully applied in various fields, namely artificial neural network (ANN) and response surface methodology (RSM), to analyze and optimize the drilling process of MDF boards. Four artificial neural network models with a reasonable accuracy were developed to predict the analyzed responses, namely delamination factor at inlet, delamination factor at outlet, thrust force, and drilling torque. These models were used to complete the experimental design that was requested by the RSM. The optimum values of the selected factors and their influence on the drilling process of the MDF boards were revealed. A part of optimum combinations among analyzed factors could be used both during the drilling of the MDF boards and prelaminated wood particleboards. Full article

(This article belongs to the Special Issue Wood Quality and Wood Processing)

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11 pages, 2642 KiB

Open AccessArticle

Thermal, Mechanical and Morphological Properties of Cellulose/Lignin Nanocomposites

by Mustafa Zor, Ferhat Şen, Hikmet Yazıcı and Zeki Candan

Forests 2023, 14(9), 1715; https://doi.org/10.3390/f14091715 - 25 Aug 2023

Cited by 1 | Viewed by 1510

Abstract

Lignin, a lignocellulosic polymer material, is an important active ingredient for the high-value use of renewable resources. Thus, policies for the recovery and high value-added use of renewable lignocellulosic biomass are a realistic engineering approach to address concerns such as the climate and [...] Read more.

Lignin, a lignocellulosic polymer material, is an important active ingredient for the high-value use of renewable resources. Thus, policies for the recovery and high value-added use of renewable lignocellulosic biomass are a realistic engineering approach to address concerns such as the climate and energy crisis. In this work, the mechanical properties, thermal stability and morphology of cellulose/lignin nanocomposites were studied. Nanocomposite films containing different proportions of lignin (2.5%, 5%, 10% and 20%) were prepared. Thermal properties were assessed via thermogravimetric analysis and differential scanning calorimetry, mechanical properties via tensile test and morphological properties via scanning electron microscopy techniques. It was observed that nanolignin and nanocellulose structures are compatible with each other and depending on the main degradation temperature, the thermal stability of 2.5% lignin-containing nanocomposites is higher than that of other composites. From the results obtained, it was determined that the nanocomposite film containing 2.5% nanolignin had high thermal stability, mechanical strength and suitable morphological structure compared to other samples. Full article

(This article belongs to the Special Issue Wood Quality and Wood Processing)

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14 pages, 6012 KiB

Open AccessArticle

Maturation Stress and Wood Properties of Poplar (Populus × euramericana cv. ‘Zhonglin46’) Tension Wood

by Yamei Liu, Xiao Wu, Jingliang Zhang, Shengquan Liu, Katherine Semple and Chunping Dai

Forests 2023, 14(7), 1505; https://doi.org/10.3390/f14071505 - 23 Jul 2023

Cited by 1 | Viewed by 1648

Abstract

Understanding the maturation stress and wood properties of poplar tension wood is critical for improving lumber yields and utilization ratio. In this study, the released longitudinal maturation strains (RLMS), anatomical features, physical and mechanical properties, and nano-mechanical properties of the cell wall were [...] Read more.

Understanding the maturation stress and wood properties of poplar tension wood is critical for improving lumber yields and utilization ratio. In this study, the released longitudinal maturation strains (RLMS), anatomical features, physical and mechanical properties, and nano-mechanical properties of the cell wall were analyzed at different peripheral positions and heights in nine artificially inclined, 12-year-old poplar (Populus × euramericana cv. ‘Zhonglin46’) trees. The correlations between the RLMS and the wood properties were determined. The results showed that there were mixed effects of inclination on wood quality and properties. The upper sides of inclined stems had higher RLMS, proportion of G-layer, bending modulus of elasticity, and indentation modulus of the cell wall but a lower microfibril angle than the lower sides. At heights between 0.7 m and 2.2 m, only the double-wall thickness increased with height; the RLMS and other wood properties such as fiber length and basic density fluctuated or changed little with height. The RLMS were good indicators of wood properties in the tension wood area and at heights between 0.7 m and 1.5 m. The results of this study present opportunities to better understand the interactions and effects of these two phenomena, which both occur quite frequently in poplar stands and can influence the wood quality of valuable assortments. Full article

(This article belongs to the Special Issue Wood Quality and Wood Processing)

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11 pages, 2763 KiB

Open AccessArticle

Effect of Samples Length on the Characteristics of Moisture Transfer and Shrinkage of Eucalyptus urophylla Wood during Conventional Drying

by Honghai Liu, Mengqing Ke, Ting Zhou and Xinlu Sun

Forests 2023, 14(6), 1218; https://doi.org/10.3390/f14061218 - 12 Jun 2023

Cited by 3 | Viewed by 1068

Abstract

Moisture transfer influences wood deformation and moisture content (MC) distribution during conventional drying of Eucalyptus urophylla wood. This study aims to investigate the effect of sample length (30, 100, and 200 mm) on moisture distribution and transfer in different directions and locations and [...] Read more.

Moisture transfer influences wood deformation and moisture content (MC) distribution during conventional drying of Eucalyptus urophylla wood. This study aims to investigate the effect of sample length (30, 100, and 200 mm) on moisture distribution and transfer in different directions and locations and on deformation of wood. The results showed that when the MC was above the fiber saturated point (FSP), the drying rate decreases exponentially with an increase of sample length; however, below the FSP, there was no obvious relationship between the drying rate and sample length and above the FSP, the moisture distribution was non-uniform along tangential, radial, and longitudinal directions and became even below the FSP, which was more significant in the middle location of wood. The greatest MC differences occurred between the surface and sub-central layers along the tangential and radial direction, which were between the end and sub-middle locations along the longitudinal direction. The effect of sample length on the MC distribution and MC differences along wood in the three directions depended on locations and the MC stage of wood; most of the free water and bound water transferred from the wood central to the ends along the longitudinal direction for three sets of samples. Bound water diffusion significantly slowed as the sample length exceeded 200 mm; sample length affects wood collapse and its recovery, but the drying rate has a lesser effect on collapse for samples with a length below 200 mm. Full article

(This article belongs to the Special Issue Wood Quality and Wood Processing)

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21 pages, 820 KiB

Open AccessArticle

Impacts of Foreign Trade on the Economy of Wood-Based Sectors Generating Different Levels of Value Added in the Slovak and Czech Republics

by Andrea Janáková Sujová, Katarína Marcineková and Václav Kupčák

Forests 2023, 14(5), 1029; https://doi.org/10.3390/f14051029 - 17 May 2023

Cited by 2 | Viewed by 1694

Abstract

Foreign trade belongs among the main sources of economic growth as classical theories of international trade affirm. The aim of the paper is to evaluate the impact of trade balance flows on sectors generating different value-added in the wood-based industries (WBI) of the [...] Read more.

Foreign trade belongs among the main sources of economic growth as classical theories of international trade affirm. The aim of the paper is to evaluate the impact of trade balance flows on sectors generating different value-added in the wood-based industries (WBI) of the Czech and Slovak Republics. The multivariate regression method (MLR) was applied to identify the relationship between foreign trade and economic indicators and also specific indicators assessing impacts of foreign trade on the economy of wood-based industries. The results showed that the performance of high value-added production is only slightly affected by foreign trade. It means that both monitored countries do not utilize raw wood so intensively that the positive effects of foreign trade are manifested. Growth in net exports represents a positive influence on the economy of the sector regardless of the value-added rate only if the increase in imports is smaller than in exports. The contribution of the study to existing knowledge is in using specific indicators evaluating trade impacts on the industry’s economy. The article provides new empirical insights into the influence of foreign trade balance flows on the economy of wood-based sectors with a different value-added rate. Full article

(This article belongs to the Special Issue Wood Quality and Wood Processing)

12 pages, 4738 KiB

Open AccessArticle

Effects of the Surface Roughness of Six Wood Species for Furniture Production on the Wettability and Bonding Quality of Coating

by Qinglin Yu, Xi Pan, Zhong Yang, Li Zhang and Jingyun Cao

Forests 2023, 14(5), 996; https://doi.org/10.3390/f14050996 - 11 May 2023

Cited by 9 | Viewed by 2021

Abstract

Wood surface roughness, surface free energy (SFE), wettability, and bonding quality for water-based acrylic coatings were investigated. The samples tested in this study included Pinus radiata, Pinus sylvestris, Larch, Hemp oak, Catalpa tree, and Camphor. Sandpaper with grits of 180, 240, [...] Read more.

Wood surface roughness, surface free energy (SFE), wettability, and bonding quality for water-based acrylic coatings were investigated. The samples tested in this study included Pinus radiata, Pinus sylvestris, Larch, Hemp oak, Catalpa tree, and Camphor. Sandpaper with grits of 180, 240, 320, 400, and 500 was utilized to sand wood surfaces. The van OSS-Chaudhury-Good equation (vOCG) was used to calculate the SFE values. The modified model (M-D) was used to calculate the wettability based on the contact angle change rate (K value). The higher the K value, the faster the contact angle approaches equilibrium. A cross-cut test was used to evaluate the coating’s bonding quality. The anatomical structure of wood has an impact on the roughness of hardwood. The equilibrium contact angle is influenced by the wood species and sandpaper grit size. Sanding can make the surface of wood more wettable. Radiata pine that had been sanded to 180 grit had the highest SFE value. After finishing with waterborne acrylic, hardwood had a slightly better coating adhesion than softwood. Hemp oak wood had the lowest coating adhesion (0.6) and the highest K value (0.82). The best bonding quality (0.4) was supplied by the camphor wood with the lowest K value (0.13). Wettability in terms of K values was a good indication of determining the bonding quality of the water-based acrylic coatings. Full article

(This article belongs to the Special Issue Wood Quality and Wood Processing)

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