Search Results (39)

Birds actively modulate their wing and tail morphologies to achieve high aerodynamic efficiency and maneuverability, enabling long-duration gliding while retaining the ability to execute rapid maneuvers. Innovations in aircraft design and control are increasingly inspired by these avian flight characteristics through control surfaces that imitate the natural wing and tail movements of birds. This paper presents a non-flapping, unmanned aerial vehicle (UAV), called “SMART Hawk” (Shape-Morphing Artificial Red-Tailed Hawk), inspired by the flight and physical characteristics of Buteo jamaicensis, known as the Red-Tailed Hawk (RTH), which exhibits excellent soaring abilities and agility characteristic of birds of prey. To determine the design parameters required for flight, a mathematical model was developed in MachUpX, then validated and refined using Reynolds-averaged computational fluid dynamics (CFD) models in ANSYS Fluent. SMART Hawk incorporates biomimetic wing and tail morphing, including coordinated forward sweep of the mid-wing and aft sweep of the outer wing, as well as active tail pitch, roll, and feather tucking and expansion. The drone was manufactured from a combination of composite, wood, and 3D-printed components. Multiple flight tests were conducted with proof-of-concept prototypes to demonstrate the design’s effectiveness. Full article

Cross-laminated bamboo (CLB) has gained increasing attention as an emerging structural material combining high mechanical performance with remarkable sustainability potential. This comprehensive review summarizes and critically discusses the main advances and trends in CLB research, drawing on experimental, analytical, and numerical approaches reported in the literature. The review highlights that the mechanical performance of CLB depends on panel architecture, bamboo product type, and adhesive systems. Reported experimental results indicate that CLB panels can achieve competitive or higher mechanical performance than selected cross-laminated timber (CLT) configurations made from specific wood species, particularly in bending, compression, tension, and rolling shear. At the same time, the literature reveals variability associated with manufacturing parameters, adhesive types, and lamella orientation, which affects the comparability of results and highlights current challenges for standardization. Structural applications investigated include floor and wall panels, beams, and rocking walls, especially for seismic-resilient building systems. Despite growing experimental evidence, most investigations remain limited to laboratory-scale elements, with modelling simplifications that constrain predictive accuracy. This review identifies the main challenges and research opportunities towards industrial scalability, standardized testing procedures, and design models adapted to the specific behavior of CLB, paving the way for its consolidation as a reliable and sustainable construction material. Full article

Paper-based printing materials originate from the wood-based value chain–wood–pulp–paper–printing—and their yield reflects the utilization efficiency of pulp and paper resources. In roll-to-roll printing production, small printing defects (e.g., missing prints, smudges, cracks) often cause rework and scrap, thereby increasing the consumption of wood-derived materials. To improve resource efficiency, this study proposes a lightweight, improved YOLOv8n model for real-time small-defect detection. The Efficient IoU (EIoU) loss is introduced in the bounding box regression stage to improve localization accuracy, and a Squeeze-and-Excitation (SE) channel attention mechanism is embedded in the feature fusion stage to strengthen feature representation for small printing defects. Evaluations conducted on datasets collected from real production lines demonstrate that, with 3.02 M parameters and 8.1 GFLOPs, the model achieves mAP@0.5 = 94.1%, Precision = 95.1%, Recall = 94.3%, and an inference speed of 100.2 FPS, outperforming the baseline model. The proposed method contributes to reducing rework and material waste, supporting the efficient utilization of wood resources and the sustainable development of the paper-based packaging industry. Full article

Accurate forecasts of the U.S. renewable energy consumption mix are essential for planning transmission upgrades, sizing storage, and setting balancing market rules. We introduce a Bayesian Dirichlet ARMA model (BDARMA) tailored to monthly shares of hydro, geothermal, solar, wind, wood, municipal waste, and biofuels from January 2010 through January 2025. The mean vector is modeled with a parsimonious VAR(2) in additive log ratio space, while the Dirichlet concentration parameter follows an intercept plus five Fourier harmonics, allowing for seasonal widening and narrowing of predictive dispersion. Forecast performance is assessed with a 61-split rolling origin experiment that issues twelve month density forecasts from January 2019 to January 2024. Compared with three alternatives (a Gaussian VAR(2) fitted in transform space, a seasonal naive approach that repeats last year’s proportions, and a drift-free ALR random walk), BDARMA lowers the mean continuous ranked probability score by 15 to 60 percent, achieves componentwise 90 percent interval coverage near nominal, and maintains point accuracy (Aitchison RMSE) on par with the Gaussian VAR through eight months and within 0.02 units afterward. These results highlight BDARMA’s ability to deliver sharp and well-calibrated probabilistic forecasts for multivariate renewable energy shares without sacrificing point precision. Full article

To increase and optimize the use of wood in structural elements, a deep understanding of its mechanical behavior is necessary. The transverse material properties of wood are particularly important for mass timber construction and for utilizing wood as a strengthening material in timber connections. This study experimentally determined the stiffness and strength of Scots pine wood under compression perpendicular to the grain and rolling shear loading, as well as their dependence on the annual ring structure. A previously established biaxial test configuration was employed for this purpose. The modulus of elasticity in the radial direction was found to be about twice that in the tangential direction (687 vs. 372 N/mm²), although the strength in the tangential direction (5.19 N/mm²) was comparatively higher than that in the radial direction (4.70 N/mm²). For rolling shear, especially for the rolling shear modulus, a large variation was found, and its relationship with annual ring structure was assessed. The obtained RS modulus ranged from 50 to 254 N/mm², while RS strength was found to be between 2.14 and 4.61 N/mm². The results aligned well with previous findings. Full article

This study prepared epoxy–clay nanocomposites (ECNs) by incorporating organophilic clays modified with either non-redox cetyltrimethylammonium bromide (CTAB) or redox-active aniline pentamer (AP), then compared their anticorrosion performance on metal substrates in saline environments. The test solution contained 2 wt% alkaline copper quaternary (ACQ) wood preservatives. Cold-rolled steel (CRS) panels coated with the ECNs were evaluated via electrochemical impedance spectroscopy (EIS) in saline media both with and without ACQ. For CRS coated with unmodified epoxy, the Nyquist plot showed impedance dropping from 255 kΩ to 121 kΩ upon adding 2 wt% ACQ—indicating that Cu²⁺ ions accelerate iron oxidation. Introducing 1 wt% CTAB–clay into the epoxy increased impedance from 121 kΩ to 271 kΩ, while 1 wt% AP–clay raised it to 702 kΩ. This improvement arises because the organophilic clay platelets create a more tortuous path for Cu²⁺ and O₂ diffusion, as confirmed by ICP–MS measurements of Cu²⁺ after EIS and oxygen permeability tests (GPA), thereby slowing iron oxidation. Moreover, ECN coatings containing AP–clay outperformed those with CTAB–clay in corrosion resistance, suggesting that AP not only enhances platelet dispersion but also promotes formation of a dense, passive metal oxide layer at the coating–metal interface, as shown by TEM, GPA, and XRD analyses. Finally, accelerated salt-spray exposure following ASTM B-117 yielded corrosion behavior consistent with the EIS results. Full article

This study investigates the structural performance of cellular cross-laminated timber (CCLT) through a nonlinear finite element model using Hill and Hashin damage criteria in Abaqus. This study evaluates these criteria in simulating CCLT’s mechanical behavior under bending and shear loading. Experimental validation included short-span and long-span bending tests, along with rolling shear tests. In bending simulations, the Hill criterion predicted maximum loads with a 7% error for long-span beams when modeling lumber as solid elements and the corrugated panel as shell elements. When the entire CCLT was modeled using shell elements, the error increased to 9%. For the short-span bending, the error remained at 8% regardless of element type. The Hashin model provided more accurate results, with deviations of 0.2% for long-span beams and 1% for short-span beams. Both models successfully predicted failure mechanisms, identifying tension failure in the lumber under long-span bending and shear failure in the corrugated core under short-span bending. In rolling shear tests, the Hill criterion underestimated the maximum shear load by 11%, while the Hashin criterion had a larger underestimation of 26%. Despite these discrepancies, both models effectively captured the nonlinear behavior of CCLT panels. These findings highlight the potential of Hill and Hashin criteria for modeling CCLT’s mechanical response, offering valuable insights into structural design applications. Full article

In the context of globalization and cultural diversity, the former residences of historical dignitaries in townships hold profound historical and cultural value, making them an important part of cultural heritage. However, as urbanization accelerates, these former residences encounter numerous challenges, necessitating a heightened focus on their protection and restoration. In this study, we utilized Wu’s Juren Mansion in Fujian as a focal point to delve deeply into the restoration design of the former residences of historical dignitaries in townships. This study covers the basic information, historical evolution, and surrounding environment of the building and investigated its damage in detail—including damage to the gatehouse, corridor, main building, roll roof, and walls—classified and counted the defect locations, and deeply analyzed the causes of damage. Based on relevant laws and regulations, we determined the nature, design principles, and foundation of the restoration project. We then formulated specific restoration measures, such as repairing and maintaining roofs, wooden structures, and walls, as well as measures for wood selection, adhesive use, and termite control. The restoration strategies and design schemes proposed in this study can effectively eliminate safety hazards, preserve the original style of the building to the greatest extent, and maintain historical and cultural value. At the same time, this research provides a reference example for the protection and development of former residences of historical dignitaries in townships and promotes the sustainable development of rural cultural heritage. Full article

Cross-laminated timber (CLT) is gaining popularity as a sustainable alternative to traditional building materials. However, the decline of natural vegetation and the growth of plantation hardwoods has led the researchers to consider alternatives. This study presents a comparative analysis of bending and rolling shear performance of homogenous poplar (Populus nigra L.) CLT and hybrid CLT, with maple (Acer platanoides L.), in the outer layer and poplar in the core, compared to spruce (Picea abies (L.), H. Karst.) CLT. The CLT panels were prepared using one-component polyurethane (1C-PUR) and melamine adhesive (ME). Poplar CLT exhibited equal or better properties than spruce CLT. The outer maple layer in the hybrid CLT enhanced the global bending modulus (E_mg) and bending strength (f_m) by 74% and 37%, respectively, due to its higher modulus of elasticity better shear resistance by reducing the cross-layer stress concentrations and rolling shear failure. Additionally, both the adhesive types and wood species significantly influenced the f_m, E_mg, and rolling shear strength (f_r) independently, while their interaction effect was found to be non-significant. The experimental bending stiffness was higher than the theoretical values. The shear analogy method provided the most accurate results for bending and shear strengths, while bending stiffness was best predicted by the modified gamma method, with minor variations. The finite-element models (FEMs) also produced results with a deviation of only 10%. Full article

Polymers are known to produce beneficial effects on asphalt mixtures, and lignin biopolymers could further improve them while contributing to sustainability and circularity. In this research, conventional asphalt emulsion was replaced with liquid waste containing lignin from the wood industry in half-warm mix asphalt (HWMA) at varying substitution levels of 0% (control), 5%, 10%, 15%, and 20%. Additionally, 100% reclaimed asphalt pavement (RAP) was used as aggregate. The impact of asphalt emulsion substitution on the mixtures’ adhesion, cohesion, and water resistance was analyzed. Indirect tensile strength tests evaluated the HWMA’s resistance to moisture damage and ductility. Rolling bottle and boiling water tests were conducted to assess the binder-aggregate affinity. Moreover, a Life Cycle Assessment (LCA) was performed to compare the environmental benefits of HWMA with those of Hot Mix Asphalt (HMA). The findings revealed that substituting asphalt emulsion with the waste lignin up to 15% enhances the mixture’s cohesion, while only substitutions up to 5% produce mixtures with enhanced water resistance. Environmental impacts were significantly reduced for all the HWMA studied, with the Global Warming Potential (GWP) showing up to 33.5% reduction compared to a conventional HMA. Full article

Defibering equipment is employed in the production of scrimber for the purpose of wood veneer rolling, cutting, and directional fiber separation. However, the current defibering equipment exhibits a notable degree of automation deficiency, relying more on manual operation and empirical methods for process control, which impedes the stability of the defibering equipment and the defibering quality. This study presented an in-depth finite element analysis of the roller-pressing process for veneer defibering equipment, and a prediction method incorporating numerical simulation and ensemble learning was proposed through data collection and feature selection. The objective is to integrate this method into the intelligent decision-making system of the equipment, with the aim of improving the productivity of the equipment and effectively stabilizing the product quality. The simulation process and the analysis of the results in ABAQUS 2020 revealed that the roller gap and roller velocity of the defibering equipment, as well as the geometrical parameters of the veneer, have a significant influence on the defibering effect. Combining these factors, 702 simulation experiments were devised and executed, and a database was constructed based on the model-building parameters and simulation outcomes. The strain and stress observed in the simulation results served to represent the veneer force and veneer deformation. The CatBoost algorithm was used to establish prediction models for the key parameters of the defibering effect, and the Bayesian Optimization and 5-fold cross-validation techniques enabled the strain and stress prediction models to achieve coefficients of determination of 0.98 and 0.97 for the training and test datasets, respectively. Shapley Additive Explanation was used to provide insight into the contribution of each feature, thereby guiding the selection of feature parameters and simplifying the model. The results show that the scheme can effectively determine the core process parameters of the defibering equipment and then provide a practical control strategy for intelligent online control. Full article

As a renewable, environmentally friendly, natural, and organic material, wood has been receiving extensive attention from various industries. However, the hydrophilicity of wood significantly impacts the stability and durability of its products, which can be effectively addressed by constructing superhydrophobic coatings on the surface of wood. In this study, tung oil, carnauba wax, and silica nanoparticles were used to construct superhydrophobic coatings on hydrophilic wood surfaces by a facile two-step dip-coating method. The surface wettability and morphology of the coatings were analyzed by a contact angle meter and scanning electron microscope, respectively. The results suggest that the coating has a micron–nanosized two-tiered structure, and the contact angle of the coating is higher than 150° and the roll-off angle is lower than 10°. Sandpaper abrasion tests and UV diffuse reflectance spectra indicate that the coatings have excellent abrasion resistance and good transparency. In addition, the coated wood shows excellent self-cleaning and water resistance, which have great potential for applications in industry and furniture manufacturing. Full article

In addition to traditional building materials, such as steel and concrete, wood has been gaining increasing prominence in recent years. In the past, the use of wood was limited due to its susceptibility to damage by fungi, insects, and temperature. These shortcomings were gradually eliminated as the quality of wood processing increased and thanks to modern high-quality insulating and protective materials. The return to the utilisation of this natural building material was also supported by the development of new wood-based materials, such as glued laminated wood, and new types of mechanical fasteners, as well as by the introduction of new design methods provided in the Eurocodes. Within this context, this paper focuses on using wood in transport infrastructure, especially as the basic material for footbridges and small road bridges. Combined timber–steel bridges emerge as a very effective type of superstructure in contemporary road bridges and footbridges, especially in areas with natural exposure. Usually, wood is used for the main bridge girders, while steel is preferred for bridge deck elements—stringers and cross-girders. The results of this parametric study offer optimal structural solutions for footbridges with spans of 12.0–24.0 m, reflecting satisfactory static and dynamic footbridge behaviour. Particular attention is paid to a problematic structural detail—the connection between the steel cross-girder and the timber main girder. Firstly, this connection’s characteristics were measured experimentally using nine laboratory samples made of two glued laminated timber blocks, simulating main girders connected with a hot-rolled steel cross-girder. The connection was prepared in three variants, with different heights of the end plates and different numbers of bolts. Subsequently, these characteristics were computed using two numerical FEM models. The first model was created using SCIA Engineer software with a combination of shell and beam finite elements. The second, more sophisticated model was created in the ANSYS software environment using 3D finite elements, allowing us to better take into account the plasticity and orthotropic properties of wood and the points of contact between the individual members. Finally, the experimental results produced by sample testing in the laboratory were compared to the outputs of FEM numerical studies. Full article

The current European standards demand more energy-efficient, comfortable, and sustainable buildings and encourage the incorporation of recycled materials in building construction. Timber buildings are successfully competing with traditional building materials in addressing these challenges; however, one of the weaknesses of timber systems is their limited sound insulation capacity. One material that can fit into the sustainability aims of timber construction and improve its acoustic performance is recycled ground tyre rubber (GTR), which, on top of this, is a serious environmental problem. This paper presents research on the use of GTR materials combined with timber systems in order to improve their acoustic performance. Three different types of GTR products (granulate, rolls, and sheets) of different thicknesses and densities are selected and are combined with different sound-absorbing materials (mineral wool, cellulose, and wood fibre) inside a lightweight timber sandwich system. In this study, the first qualitative approach, the acoustic performance of the different resulting systems is compared based on the sound pressure level difference measured in a custom-made reduced-size transmission chamber. Secondly, the sound reduction index of four selected specimens is measured in an accredited sound transmission laboratory. The results show that, for all the lightweight timber systems included in this research, introducing a GTR layer improves the acoustic performance of the system. Full article

The structural properties and whiteness of the substrate surface markedly effect printing quality and are closely related to the primer coating processes. Herein, four different roller coating schemes were applied on MDF surfaces to change their structural properties and color, and the whiteness, gloss, and roughness properties of the substrate surfaces were characterized for UV inkjet printing. Data analysis was conducted to explore the effects of these variables on the color reproduction, relative contrast, and printing gloss of the MDF substrates. The results showed that, according to CMYK, L*a*b* values and spectral reflectance data, the finishing of the MDF substrate with a 40 g/m² layer of transparent primer combined with three layers of white primer at 20 g/m² per roll coating layer had the best color reproduction effect for UV inkjet printing. Regarding the effects of relative contrast, the correlation with whiteness and glossiness was significant, while the correlation with glossiness was minor. The inkjet printing gloss value was positively correlated with substrate primer surface whiteness, while it was negatively correlated with roughness. When the surface whiteness of the substrate was relatively high, the roughness was lower and the printing effects were glossier. We sought to optimize the printing effects of all aspects of the MDF substrate by primer coating. The results of this work provide a feasible application method to improve printing quality and enhance the added value of low-quality boards, as well as to further expand the application of UV inkjet printing in the wood decoration market. Full article