Search Results (6,947)

Conventional buckling-restrained braces (BRBs) with rectangular steel tube confinement suffer from stress concentration and inefficient material utilization, limiting their seismic performance. To address these limitations, this study proposes a novel non-rectangular concrete-filled steel tube BRB system incorporating elliptical and corrugated cross-sections. Comprehensive finite element simulations using ABAQUS are conducted to systematically investigate the influence of key geometric parameters—wall thickness (1–14 mm), corner radius (40–55 mm), and corrugation angle (30–75°)—on hysteretic behavior, load-bearing capacity, and failure modes. The results demonstrate that optimized non-rectangular sections achieve load-bearing capacity comparable to conventional rectangular designs (e.g., elliptical section with 12 mm wall thickness reaches 10.02 MN, a 75% increase over 1 mm thickness) while significantly improving material efficiency. Corrugated sections exhibit enhanced weak-axis performance, with equivalent viscous damping ratios exceeding the NIST-recommended threshold of 0.25. Parametric analyses reveal that wall thickness above 12 mm yields diminishing returns; corner radius reduction to 40 mm triggers local buckling yet increases peak capacity; and corrugation angles exceeding 50° induce instability. All non-buckling models satisfy AISC compression strength adjustment factor requirements (β ≤ 1.3). This study systematically evaluates non-rectangular BRB geometries, filling a critical gap in the literature and providing design guidelines that leverage shape optimization to enhance both seismic resilience and material economy. Full article

This study analyzes the effect of two bioactive additives—caffeic acid and natamycin (Natamax^®)—on the properties of poly(butylene succinate) (PBS) in the context of applications in biodegradable active packaging. Materials containing 1, 3, and 5 wt.% of the additives were prepared by melt blending and characterized in terms of density, rheological behavior (MFR), mechanical properties, thermal stability (TGA), and thermal behavior and crystallization (DSC). Caffeic acid strongly reduced the melt viscosity (reflected by a significant increase in MFR) and, at higher concentrations, led to material stiffening and increased strength at the expense of a pronounced reduction in deformability. Natamycin exhibited a milder rheological effect; at 1 wt.% it simultaneously improved strength and elastic modulus, whereas at higher loadings it deteriorated mechanical performance due to structural effects. Both additives were thermally compatible with PBS; caffeic acid introduced an additional degradation step, while Natamax^® did not significantly alter the degradation mechanism. The results indicate that both the type and concentration of the additive govern the structure–property–function relationships and enable the design of PBS-based packaging materials with controlled performance and functional characteristics. Full article

The anti-aging performance of stay cables in complex marine environments is directly related to the long-term service safety of sea-crossing cable-stayed bridge structures, and it has been recognized as one of the key issues for the priority evaluation of the structural performance of sea-crossing cable-stayed bridges with Basalt Fiber Reinforced Polymer (BFRP) cables. In this paper, the coupled aging effects of ultraviolet radiation, salt spray, temperature and humidity, and prestress on BFRP cables were taken into consideration. Accelerated aging tests involving the coupling of light, heat, water, salt, and prestress were carried out to simulate the actual marine service environment. The anti-aging performance of BFRP cables was investigated by combining the analysis of macro mechanical properties with the characterization of micro structural morphology. The results of the study were as follows: (1) With the increase in aging duration, the tensile strength and ultimate fracture strain of BFRP cables decreased gradually. The degradation rates of tensile strength and ultimate fracture strain of BFRP cables exhibited a decreasing trend, characterized by an initial rapid phase followed by a gradual slowdown under the coupled aging effects of light, heat, water, salt, and prestress. (2) Compared with the significant decrease in tensile strength, the elastic modulus of BFRP cables showed an insignificant decrease. The elastic modulus of BFRP cables was observed to exhibit a trend of initial decrease, subsequent increase, and another decrease, with an overall reduction. (3) Temperature and prestress were verified to exert a considerable influence on the anti-aging performance of BFRP cables. The influence of temperature on the degradation of aging performance of BFRP cables was found to be greater than that of prestress. (4) The degradation in the anti-aging performance of BFRP cables under coupled aging effects was confirmed to originate from the initiation and propagation of microcracks in the resin matrix, which were caused by the combined actions of prestress, photochemistry, and hydrolysis. Meanwhile, the damage to the fiber–resin interface was accelerated by chloride ions in seawater under high-temperature conditions, which ultimately led to a reduction in the anti-aging performance of BFRP cables. Full article

Delamination in laminated composites originates from premature matrix cracking within the interlaminar region, ultimately leading to ply separation under indirect loading. Among the techniques proposed to mitigate this failure mode, through-thickness stitching has emerged as a localized reinforcement strategy capable of enhancing interlaminar performance without modifying the in-plane laminate architecture. However, previous studies report that stitching can either improve or degrade the mechanical properties of the composite, with stitch density identified as a critical variable. This work aims to keep the tensile strength of a stitched composite at levels comparable to its unstitched counterpart. The reinforcement was applied using an eight-strand polyethylene thread (0.28 mm in diameter) embedded in a low-viscosity epoxy infusion system (MAX 1618 A/B) combined with a 90° biaxial fiberglass woven fabric. The tensile behavior of laminates was examined for three longitudinal stitching configurations consisting of 2, 3, and 5 continuous stitch lines. Results show that increasing stitch count produces a progressive reduction in tensile strength, attributed to stress concentration around stitch sites and microstructural effects such as resin-rich zones and fiber waviness. Full article

Reinforcement corrosion is one of the primary deterioration mechanisms affecting the long-term seismic performance of reinforced concrete (RC) structures. Although the effects of corrosion on individual RC members have been widely investigated, its influence on the cyclic behavior of RC frame systems has received limited attention. This study numerically investigates the seismic response of a single-bay reinforced concrete frame subjected to cyclic lateral loading under various corrosion scenarios. A three-dimensional nonlinear finite element model was developed in ABAQUS, incorporating corrosion-induced effects such as reinforcement cross-sectional loss, degradation of mechanical properties, bond strength deterioration, and concrete softening. The corrosion propagation rate and exposure duration were considered as key parameters, and different corrosion scenarios were comparatively evaluated. The numerical model was validated using an experimentally tested non-corroded reinforced concrete frame subjected to cyclic loading. The results demonstrate that reinforcement corrosion leads to significant degradation in the seismic performance of RC frames. Depending on corrosion severity, reductions of up to approximately 25% in lateral load capacity and up to 27% in both initial stiffness and energy dissipation capacity were observed. The findings further indicate that stiffness- and energy-based performance indicators are more sensitive to corrosion damage than strength-based indicators. The study highlights the importance of explicitly accounting for corrosion effects in the seismic performance assessment of reinforced concrete frame systems and provides a practical numerical framework for evaluating corrosion-induced performance degradation. Full article

Background and Objectives: Peak Cough Flow (PCF) is an objective measure of cough effectiveness, traditionally used in patients with neuromuscular disorders. Sarcopenia may also impair respiratory muscles, but its relationship with cough efficacy in hospitalized patients with respiratory diseases is not well established. This study investigated the correlation between PCF and sarcopenia indicators and evaluated the influence of comorbidities, anthropometric variables, and body position on PCF. Methods: A cross-sectional observational study was performed. PCF was measured using a portable peak flow meter in seated and supine positions. Sarcopenia was assessed through handgrip strength and validated questionnaires. Comorbidity burden was quantified using the Charlson Comorbidity Index (CCI). Nutritional status and sleep apnea risk were evaluated with the Mini Nutritional Assessment–Short Form (MNA-SF) and STOP-BANG questionnaire. Correlation analyses and linear regression were performed. Results: 53 patients were enrolled (mean age 72.6 ± 15.2 years; 64% male). Men showed significantly higher PCF values than women in both seated (p < 0.001) and supine positions (p < 0.001). Sarcopenic patients exhibited reduced PCF compared to non-sarcopenic subjects (p = 0.037). Handgrip strength was strongly correlated with PCF in seated and supine positions (p < 0.0001). CCI was negatively correlated with PCF (seated r² = 0.17, p = 0.0021; supine r² = 0.16, p = 0.0027). No significant associations were observed with BMI, MNA-SF, or STOP-BANG. Postural change resulted in comparable PCF reduction in men and women (ΔPCF: 20 ± 37.9 vs. 17 ± 37.9 L/min). Conclusions: Sarcopenia and comorbidity burden are significantly associated with reduced cough efficacy. Handgrip strength is a strong predictor of PCF, supporting routine PCF assessment beyond neuromuscular populations. Full article

Prefabricated reinforced concrete shear wall structures have attracted significant attention due to their advantages in industrialized construction and sustainability. However, the structural performance of prefabricated shear wall systems still requires further investigation to ensure reliable seismic behavior under earthquake loading. In this study, a fully prefabricated shear wall system incorporating keyway interlocking joints and concentrated reinforcement connections is proposed, and its nonlinear seismic behavior is systematically investigated through finite element modeling, parametric analysis, nonlinear time history analysis, and incremental dynamic analysis. The finite element models were validated against available experimental results and reproduced the hysteretic response, stiffness degradation, and load-carrying capacity with good agreement. The relative errors in peak load were within 5%, indicating the reliability of the adopted modeling approach. Parametric analyses indicate that axial compression ratio, concrete strength, and wall thickness significantly affect structural performance, while prefabricated walls exhibit slightly lower stiffness and strength than cast-in-place walls, with mean reduction factors of 0.88 and 0.91. An eight-story prefabricated shear wall building subjected to multiple scaled ground motions exhibits stable flexure-dominated deformation without joint sliding or soft-story mechanisms. Peak roof displacements reached 19.71 mm and 32.85 mm in the X and Y directions, with maximum interstory drift ratios of 1/892 and 1/724. These values are significantly smaller than the commonly adopted collapse drift limit of 1/120 specified in seismic design guidelines, indicating a relatively large deformation safety margin under the ground motions considered. Probabilistic seismic demand models were established based on both PGA and Sa(T₁, 5%) intensity measures, showing strong correlations with the maximum interstory drift ratio. Fragility analysis demonstrates a high probability of remaining in intact or slight damage states under frequent and design-level earthquakes and a low collapse probability under rare earthquakes. These findings provide valuable insights for the design of next-generation prefabricated shear wall systems with mechanical interlocking joints and concentrated reinforcement connections. Full article

With the growing penetration of photovoltaic (PV) generation, robust uncertainty characterization is essential for secure operation, economic dispatch, and flexibility planning. This review surveys PV scenario generation from three perspectives: (i) explicit probabilistic approaches (distribution fitting, Copula-based dependence modeling, autoregressive moving average (ARMA)-type time-series methods, and clustering/dimensionality reduction), (ii) deep generative models (GANs, VAEs, and diffusion models), and (iii) hybrid Statistical Relational AI (SRAI) frameworks. We discuss the strengths of explicit models in interpretability and tractability, and their limitations in representing high-dimensional nonlinear, multimodal, and multiscale spatiotemporal dependencies. We also examine the ability of deep generative methods to synthesize diverse scenarios across meteorological regimes and multiple sites, while noting persistent challenges in interpretability, physical consistency, and deployment. To bridge these gaps, we outline an SRAI-oriented integration pathway that embeds statistical structure, meteorology–power relations, spatiotemporal coupling, and operational constraints into generative architectures. Finally, we highlight directions for future research, including unified evaluation protocols, cross-regional data collaboration, controllable extreme-scenario generation, and computationally efficient generative designs. Full article

Low-velocity impacts can cause barely visible impact damage (BVID) in carbon-fiber-reinforced polymer (CFRP) laminates, leading to significant reductions in residual compressive strength. Compression-after-impact (CAI) tests are therefore essential for damage-tolerance design, but existing fixtures often allow global buckling or edge crushing, which can compromise test accuracy. This study experimentally investigates the CAI response of two symmetric angle-ply CFRP laminates with reversed stacking sequences, [0/−45/45/90]s and [90/45/−45/0]s, using a modified CAI fixture. Compared to standard CAI rigs, the modified fixture combines the lateral guidance with anti-buckling plates that clamp the upper and lower specimen edges using a bolt–nut assembly, thereby reducing the active gauge length and stabilizing the panel during compression. Rectangular plate specimens were first impacted at low velocity with a hemispherical projectile; the BVID threshold was defined by a permanent indentation depth of 0.8 mm for [0/−45/45/90]s and 0.7 mm for [90/45/−45/0]s, measured 24 h after impact. Subsequent CAI tests showed about a 22% reduction in maximum compressive load at the BVID level for both layups, while the post-impact compressive stiffness decreased by 17% for [0/−45/45/90]s and 6% for [90/45/−45/0]s. These results demonstrate that reversing the symmetric layup significantly affects stiffness degradation and that the proposed CAI setup suppresses global buckling and edge-dominated failures in all testson the investigated thin CFRP laminates, enabling repeatable residual-strength and stiffness measurements. Full article

The development of bio-based functional materials through the upcycling of agri-food residues represents a sustainable strategy to reduce environmental impact and promote circular economy. This study achieved valorization by combining two tomato by-products: peels exhausted after supercritical fluid extraction and harvest residues mainly composed of stems and field wastes. Polyphenol-rich extract (TPPf) was obtained from peels through ultrasound-assisted maceration and solid-phase extraction, while cellulose from tomato harvest residues (THRs) was converted into carboxymethyl cellulose (THR-CMC, degree of substitution 0.76), as confirmed by structural analyses. Functional bioplastic films were prepared by solvent casting THR-CMC, plasticized with glycerol, and enriched with different TPPf concentrations (0–100 mg/100 mL). Increasing TPPf content enhanced mechanical strength and UV-blocking efficiency, while moderate loading improved moisture barrier properties. The films exhibited notable antioxidant activity (ABTS, DPPH assays) and biodegradability, demonstrating biofunctional performance suitable for food packaging. This integrated valorization strategy highlights the potential of combining agricultural and industrial tomato residues to develop sustainable, biodegradable, and active packaging materials, supporting waste reduction and circular bioeconomy objectives. Full article

Additive manufacturing enables the fabrication of personalized protective equipment with locally tailored mechanical properties. In this work, a low-cost scan-to-print workflow is proposed for the fused filament fabrication (FFF) of personalized dual-zone shin guards combining a stiff outer load-distribution layer with a compliant inner energy-absorbing layer. Subject-specific leg geometry was acquired via structured-light 3D scanning and used to design a shin guard with two 3.5 mm thick zones (total thickness 7 mm). Foamable filaments of PLA, ASA, and TPU were employed to manufacture unfoamed and foamed regions by controlling extrusion temperature. Mechanical performance was assessed through three-point bending tests and dynamic finite element impact simulations. Unfoamed PLA and ASA exhibited flexural strengths of approximately 88 MPa and 72 MPa, respectively, while foaming reduced these values by about 74%. Dual-zone configurations partially restored stiffness, reaching 41 MPa for PLA and 29 MPa for ASA. TPU showed lower flexural stresses with a smaller reduction of 23% upon foaming. Impact simulations revealed maximum deformations of 1.97 mm and 2.02 mm for PLA and ASA outer zones, respectively, while TPU exhibited large deformations leading to penetration of the 3.5 mm thick inner layer. The results demonstrate that dual-zone designs manufactured via foaming-enabled FFF can effectively balance stiffness, weight, and impact response for personalized shin guard applications. Full article

The growing consumption of natural aggregates in concrete production has raised significant environmental and sustainability concerns, motivating the search for alternative and waste-based materials. Walnut shells (WSs), an abundant agricultural by-product, have attracted increasing attention as a potential partial replacement for fine and coarse aggregates in concrete. This study presents a comprehensive review and comparative analysis of published experimental data examining the influence of WS incorporation on the fresh and hardened properties of concrete. Data from the literature covering WS replacement ratios ranging from 1% to 50% were systematically compiled and evaluated with respect to compressive strength, splitting tensile strength, flexural strength, slump, and density. The results indicate that low WS replacement levels (generally ≤10%) may preserve acceptable mechanical performance while contributing to sustainability objectives, whereas higher replacement ratios lead to pronounced reductions in strength, particularly in splitting tensile and flexural capacities. Workability consistently decreases with increasing WS content due to the porous structure and high water absorption of the shells, while density reductions suggest the potential for producing lightweight concrete. Overall, the findings demonstrate that WSs can be effectively utilized in concrete at limited replacement levels, provided that mix design parameters and performance requirements are carefully balanced. The study also highlights the need for further research focusing on durability, long-term behavior, and optimization strategies to enhance the practical applicability of WS-based sustainable concrete. Full article

Initial excavation-induced damage may alter water-driven weakening and failure in bedded shale, yet direct experimental evidence from comparable loading–hydration routes remains limited. In this study, uniaxial compression tests with acoustic emission (AE) monitoring were conducted on bedded shale from the Longmaxi Formation in the Sichuan Basin, China, under two routes, i.e., direct saturation (DS) and pre-damage followed by saturation (PDRS), across seven bedding orientations from 0° to 90°. Pre-damage was introduced by loading–unloading to 0.6 of the orientation-dependent peak strength, producing measurable defects and reducing P-wave velocity by an average of 1.23% while preserving the overall anisotropic pattern of wave propagation. Compared with DS, PDRS caused clear mechanical deterioration, with mean reductions of 37.63% in peak strength and 31.14% in elastic modulus. Both routes retained pronounced bedding-angle dependence, although the locations of minimum strength and stiffness differed between them. AE activity in the PDRS group generally initiated earlier and accumulated more persistently before peak stress. RA–AF analysis showed that tensile-like cracking dominated across all bedding orientations in PDRS, whereas the DS group exhibited stronger orientation-dependent variation in cracking mode. The b-value range was also narrower in PDRS than in DS, indicating reduced dispersion of event-size statistics among orientations. Macroscopically, failure evolved from more distributed multi-crack and mixed-mode patterns in DS to more localized dominant-fracture failure with reduced branching in PDRS. Overall, the results suggest that pre-damage before saturation changes the subsequent weakening and fracture development of bedded shale during reloading. Full article

Macrosegregation in continuous casting slabs remains a critical defect that adversely affects the homogeneity and mechanical properties of the final rolled products. Industrial experiments were conducted on E355 steel continuous casting slabs to investigate the effects of electromagnetic stirring (EMS) and soft reduction (SR) on the evolution of slab macrosegregation. Furthermore, the inheritance of segregation from the slab to the rolled plate was analyzed. The results indicate that the equiaxed crystal ratio increases and the centerline segregation decreases with increasing stirring intensity. The application of both secondary EMS and SR minimized the centerline segregation in the slab. When the current intensity was increased from 0 A to 320 A in continuous stirring mode, the equiaxed crystal fraction increased from 22.52% to 32.52%, and the centerline segregation index decreased from 1.23 to 1.17. Compared with the continuous stirring mode, the alternating stirring mode promoted a more pronounced increase in the equiaxed crystal ratio and a further reduction in the centerline segregation. The centerline segregation in the slab correlates with the banded structure observed in the rolled plate. A higher degree of slab centerline segregation corresponds to a more severe banded structure and greater fluctuations in the mechanical properties of the plate. Through parameter optimization, the recommended settings are an alternating stirring mode with a current of 320 A at 5 Hz and an SR amount of 3 mm. Under these optimized conditions, the equiaxed crystal ratio of the slab increased to 35.22%, the centerline segregation index dropped to 1.15, and the banded structure in the rolled plate was reduced to grade 2.0. Consequently, the standard deviations of the tensile strength and elongation were 8.03 MPa and 1.1%, respectively. Full article

This study investigated the effects of black chokeberry (Aronia melanocarpa) (Michx.) Elliott powder addition (0.1–0.4%) on the quality attributes of cheese snacks produced from a blended camel–goat–cow milk base (60:20:20) using microwave vacuum drying. The snacks were evaluated for chemical composition, colour parameters, texture profile and water activity in order to assess how black chokeberry incorporation influences their physicochemical and sensory-related properties. Chemical analysis showed that the high protein content of the dried cheese matrix was maintained across all formulations, while fat, carbohydrate and energy values varied within a relatively narrow range, without a clear dose-dependent trend attributable solely to black chokeberry addition. Black chokeberry powder induced concentration-dependent colour changes, with decreased lightness and increased redness and overall colour difference, indicating visually noticeable shifts that may enhance product differentiation. Texture profile analysis revealed a significant reduction in fracturability at intermediate inclusion levels, suggesting a less brittle structure, whereas other texture parameters showed non-linear but statistically non-significant variations due to limited replication. All snacks exhibited very low water activity, consistent with shelf-stable, low-moisture products. A preliminary sensory test with untrained assessors indicated that black chokeberry-enriched snacks, particularly at around 0.3%, were generally well accepted, although the small panel size limits the strength of these conclusions. Overall, the findings suggest that small additions of black chokeberry powder can be used to develop visually attractive, high-protein cheese snacks with promising textural and sensory characteristics, while more comprehensive studies are needed to characterise their antioxidant properties, detailed nutritional profile and long-term stability. Full article