Search Results (519)

To address the problems of high unharvested rates and header loss rates in existing plot-breeding wheat harvesters, this study presents the design of a comb-type header for plot wheat harvesters. Based on the loss suppression mechanism during wheat harvesting, the key components of the comb-type header were designed. To address the issue in which some wheat ears escape combing during the harvesting process, a multi-stage comb-tooth structure was developed. For the problem of seed retention on the bottom plate of the screw conveyor, the telescopic tooth at the feeding port of the screw conveyor was replaced with a scraper, and a rubber plate was added. To determine the optimal combing time, wheat plant posture changes under the action of the nose (hereinafter referred to as the nose) were analyzed through theoretical analysis, simulation, and bench testing. It was determined that the optimal combing moment occurs when the plants begin to rebound to the maximum reverse bending. On this basis, a numerical simulation model of the header combing system was constructed using the discrete element method, with the header loss rate as the evaluation index to explore the influence of the nose height, the machine forward speed, and the combing drum rotation speed on the header performance. A regression model of header loss was constructed using the Box–Behnken response surface method, and the optimal working parameters were determined as follows: a nose height of 554 mm, a machine forward speed of 0.65 m/s, a combing drum rotation speed of 667 r/min, and the predicted loss rate of 8.59%. To verify the operational performance of the comb-type header, a field test of the wheat-harvesting prototype was conducted. The results showed that, under the optimal working parameters, the header loss rate was 7.24%, no wheat ears escaped combing, and no seed retention occurred in the header, which meets the requirements for plot wheat-breeding harvesting. This study provides a theoretical basis for the design and development of small-sized combing harvesters. Full article

The objective of this study is to investigate the friction performance between tire rubber and rubberized asphalt mortar. The friction force and dynamic friction coefficient (DFC) were selected as the characterization indexes for the friction performance between the tire and the rubberized asphalt mortar, and the tests were carried out using a friction coefficient tester. The variations in material parameters, namely crumb rubber content (CRC), filler-to-binder ratio (F/B), filler particle sizes and aging conditions of rubberized asphalt mortar on friction properties were analyzed, for which significance analysis was carried out. Results show that rubberized asphalt mortar composed of different material parameters exhibit different friction properties. Filler-to-binder ratio and crumb rubber content were identified as significant predictors of the friction properties in rubberized asphalt mortar, and as these factors increase, the friction coefficient between rubber asphalt mortar and tire rubber is increased. Higher crumb rubber content (30%) reduces the temperature sensitivity of friction. In contrast, an increase in F/B exacerbates the temperature-induced variation in DFC, with F/B = 1.2 showing 2.1% DFC increase from −20 °C to −10 °C versus 0.6% for F/B = 0.6. Filler particle sizes, aging degree, and temperature showed no statistically significant effects on DFC (p > 0.1). Full article

This study aims to propose a defect diagnosis method for distribution cable intermediate joints based on microwave reflection. The research focuses on 10 kV cold-shrink-type distribution cable intermediate joints, employing both simulation analysis and experimental methods. Firstly, a microwave defect detection model for intermediate joints is derived. CST simulations are conducted to analyze the variation of the reflection coefficient (S₁₁) under different detection frequencies, defect depths, and defect types. Next, flat plate and real prototype samples of intermediate joints with defects such as insulation scratches, conductive impurities, and moisture ingress are fabricated. A microwave reflection detection platform is established to test the artificially defective samples. Reflection voltage signals corresponding to different defects are obtained. The concept of the relative value of the reflection voltage difference is then introduced, resulting in significant changes in the detection results, which effectively indicate the presence of different defects. Finally, the reflection voltage signals under different defect sizes, silicone rubber thicknesses, detection distances, and detection angles are studied. The results show that this method is capable of detecting defects as small as 2 mm in width and 0.2 mm in depth. The silicone rubber thickness, detection distance, and detection angle significantly affect the detection results. This demonstrates that microwave reflection signals can effectively identify the type and severity of defects within cable intermediate joints, and the method can be extended to detect internal defects in other layered composite insulation structures. Full article

Detecting Escherichia coli on food preparation and processing surfaces is critical for ensuring food safety and preventing foodborne illness. This study focuses on detecting E. coli contamination on common food processing surfaces using UV-C fluorescence imaging and deep learning. Four concentrations of E. coli (0, 10⁵, 10⁷, and 10⁸ colony forming units (CFU)/mL) and two egg solutions (white and yolk) were applied to stainless steel and white rubber to simulate realistic contamination with organic interference. For each concentration level, 256 droplets were inoculated in 16 groups, and fluorescence videos were captured. Droplet regions were extracted from the video frames, subdivided into quadrants, and augmented to generate a robust dataset, ensuring 3–4 droplets per sample. Wavelet-based denoising further improved image quality, with Haar wavelets producing the highest Peak Signal-to-Noise Ratio (PSNR) values, up to 51.0 dB on white rubber and 48.2 dB on stainless steel. Using this dataset, multiple deep learning (DL) models, including ConvNeXtBase, EfficientNetV2L, and five YOLO11-cls variants, were trained to classify E. coli concentration levels. Additionally, Eigen-CAM heatmaps were used to visualize model attention to bacterial fluorescence regions. Across four dataset groupings, YOLO11-cls models achieved consistently high performance, with peak test accuracies of 100% on white rubber and 99.60% on stainless steel, even in the presence of egg substances. YOLO11s-cls provided the best balance of accuracy (up to 98.88%) and inference speed (4–5 ms) whilst having a compact size (11 MB), outperforming larger models such as EfficientNetV2L. Classical machine learning models lagged significantly behind, with Random Forest reaching 89.65% accuracy and SVM only 67.62%. Overall, the results highlight the potential of combining UV-C fluorescence imaging with deep learning for rapid and reliable detection of E. coli on stainless steel and rubber conveyor belt surfaces. Additionally, this approach could support the design of effective interventions to remove E. coli from food processing environments. Full article

This work examines the impact of integrating recycled rubber particles on the dynamic mechanical properties of polyester/fiberglass (P/F) composites. Rubber particles of several mesh sizes (M20 and M40) and volume fractions (10%, 20%, and 30%) were included in the P/F composite. The findings indicate that increasing rubber content reduces density and affects the tensile strength and fracture characteristics of the composites. Rubber often decreases stiffness while potentially enhancing damping, contingent on its interaction with the polyester matrix. The P/F/M40_20% composite demonstrates significant stiffness and moderate damping, indicating a distinctive reinforcing mechanism. The relationship between rubber tensile strength and fractured behavior is complex. M40 composites weaken at 30% owing to debonding, but M20 composites only slightly decrease in strength at 20% rubber. Interestingly, M20_30% has increased strength due to rubber–fracture interactions. Fiberglass reinforcement stiffens the material but reduces vibration absorption. Rubber enhances flexibility and may attenuate vibrations. A weighted scoring method determines that the P/F/M20_20% rubber composite is the most advantageous for attaining equilibrium of toughness, strength, and damping characteristics. This work elucidates how to optimize the performance of P/F composites by modifying the properties of rubber particles for targeted applications. Full article

This work evaluated the effect of coffee oil epoxide (COE), produced from coffee waste, on thermal, mechanical, barrier, and exudation resistance properties of poly(3-hydroxybutyrate-co-3-hydroxyvalerate)/natural rubber (PHBV/NR) blends. Building upon previously published 0.3% COE results, this study examined 0.4% and 0.75% concentrations to optimize performance. Thermal analysis revealed that COE incorporation significantly enhanced chain mobility, with glass transition temperature depressions of 6.1 °C and 7.4 °C for 0.4% and 0.75% COE formulations, respectively, compared to unplasticized PHBV/NR blends. Crystallinity decreased from 54.5% (PHBV/NR) to 52.6% and 51.9% with increasing plasticizer concentration, while melting temperatures decreased by 3.9% and 4.9%, confirming improved polymer chain mobility. Mechanical properties demonstrated COE’s plasticizing effectiveness, with tensile strength decreasing by 13.3% (0.4% COE) and 16.2% (0.75% COE) compared to PHBV/NR blends. Young’s modulus similarly decreased by 21.0% and 24.0%, while elongation at break improved slightly with increasing COE content. Barrier properties improved substantially across all concentrations: water vapor transmission rates decreased from 4.05 g/m²·h (PHBV/NR) to 1.55 g/m²·h (0.3% COE) and 0.67 g/m²·h for 0.4% and 0.75% COE, attributed to COE’s hydrophobic nature. SEM morphological analysis confirmed improved phase compatibility at 0.40% COE, with reduced rubber droplet size and homogeneous surface morphology. Exudation testing revealed excellent retention (0.21–0.53 wt% loss over 63 days). Results indicate 0.40% COE as optimal, achieving superior barrier properties while maintaining mechanical performance for sustainable packaging applications. Full article

Airborne micro- and nanoplastic particles (MNPs) are increasingly recognized as a potential occupational exposure hazard, yet substance-specific workplace data remain limited. This study quantified airborne MNP concentrations during polyester microfiber production using a correlative SEM–Raman approach that enabled chemical identification and size-resolved particle characterization. The aerosol mixture at the workplace was dominated by sub-micrometer particles, with PET—handled onsite—representing the main process-related MNP type, and black tire rubber (BTR) forming a substantial background contribution. Across both sampling periods, total MNP particle number concentrations ranged between 6.2 × 10⁵ and 1.2 × 10⁶ particles/m³, indicating consistently high particle counts. In contrast, estimated MNP-related mass concentrations were much lower, with PM₁₀ levels of 12–15 µg/m³ and PM_2.5 levels of 1.3–1.6 µg/m³, remaining well below applicable occupational exposure limits and near or below 8 h-equivalent WHO guideline values. Comparison with earlier workplace and indoor studies suggests that previously reported concentrations were likely underestimated due to sampling strategies with low efficiency for small particles. Moreover, real-time optical measurements substantially underestimated particle number and mass in this study, reflecting their limited suitability for aerosols dominated by small or dark particles. Overall, the data show that workplace MNP exposure at the investigated site is driven primarily by very small particles present in high numbers but low mass. The findings underscore the need for substance-specific, size-resolved analytical approaches to adequately assess airborne MNP exposure and to support future development of MNP-relevant occupational health guidelines. Full article

This study addresses the need for flexible and high-toughness materials for transmission tower pile foundations subjected to typhoons and earthquakes by investigating the static and dynamic mechanical behavior of rubberized concrete prepared using vibratory mixing. The objectives are to assess how vibratory mixing influences strength evolution, failure modes, strain rate sensitivity, and energy absorption of rubberized concrete compared with conventional mixing at 0%, 20%, and 30% rubber contents. Quasi-static compression tests and Split Hopkinson Pressure Bar (SHPB) dynamic compression tests were conducted to quantify these effects. The results show that vibratory mixing significantly improves the paste–aggregate–rubber interfacial structure. It increases the compressive strength by 8.4–30% compared with conventional mixing and reduces the strength loss at the 30% rubber content from 51.12% to 38.98%. Under high-speed impact loading, vibratory mixed rubber concrete exhibits higher peak strength, stronger energy absorption capacity, and a more stable strain rate response. The mixture with 20% rubber content shows the best comprehensive performance and is suitable for impact-resistant design of transmission tower foundations. Future research should extend this work by considering different rubber particle sizes and vibratory mixing frequencies to identify optimal combinations, and by incorporating quantitative fragment size distribution analysis under impact loading to further clarify the fracture mechanisms and enhance the application of rubberized concrete. Full article

This study examines the use of electronic waste (e-waste) as an alternative material in concrete for sustainability and natural resource conservation. Various e-wastes, such as Polyvinyl Chloride (PVC), Glass-Reinforced Plastic (GRP), Glass Fiber-Reinforced Polymer (GFRP), cross-linked polyethylene (XLPE), polyethylene (PE), electronic cable waste (ECW), Waste Electrical Cable Rubber (WECR), copper fiber (Cu Fib.), aluminum Fibers (Al fib.), steel fibers, basalt fibers, glass fibers, aramid−carbon fibers, Kevlar fibers, jute fibers, and optical fibers, were tested for influence on compressive, flexural, tensile strength, modulus of elasticity, and water absorption. Outcomes show that fine particle waste at low levels (0.2–1.5%) can improve mechanical performance, while higher levels of replacement or coarse particles generally reduce performance. Mechanical and physical properties are highly sensitive to material type, particle size, and dose. Life cycle assessment (LCA) and predictive modeling are recommended as validation for sustainability benefits. Full article

Dental composites are commonly used for the restoration of hard tooth tissues, but their low fracture toughness may limit their lifespan. In this study, the effect of liquid rubber modification on the mechanical properties and fracture mechanisms of two types of dental composites, flow and classic, was evaluated. The study used experimental composites containing a mixture of dimethacrylate resins: BisGMA (20% by weight), BisEMA (30% by weight), UDMA (30% by weight), and TEGDMA (20% by weight). Composites were reinforced with Al-Ba-B-Si glass, Ba-Al-B-F-Si glass with particle sizes of 0.7 and 2 μm respectively, as well as pyrogenic silica (20 nm). The inorganic phase was introduced in an amount of 50% vol. for flow material and 80% vol. for classic composite. As a modifier, Hypro 2000X168LC VTB liquid rubber (Huntsman International LLC, USA) was used in an amount of 5% by weight relative to the matrix. The flexural strength, Young’s modulus, and fracture toughness were evaluated. Numerical FEM analysis allowed for the evaluation of stress distribution in the filling area. The results confirmed that the modification of composites with liquid rubber contributes to an increase in fracture toughness. For the flow-type material, the fracture toughness increased from 1.04 to 1.13 MPa·m^1/2. At the same time, a decrease in flexural strength from 71.90 MPa to 61.48 MPa and in Young’s modulus from 2.98 GPa to 2.53 GPa. In the case of the classical composite, the modification with liquid rubber also improved the resistance to fracture, increasing it from 1.97 to 2.18 MPa·m^1/2 while the flexural strength decreased from 102.30 MPa to 90.96 MPa, and the modulus dropped from 7.33 GPa to 6.16 GPa. FEA analysis confirmed that modified composites exhibit a more favorable stress distribution with lower tensile stress levels (approximately 20 MPa in contrast to 25 MPa for the classic composite). Mechanisms of fracture and strengthening were also identified. The main fracture mechanism was intermolecular cracking with crack deflections. Modification with liquid rubber resulted in the formation of elastic bridges and plastic shear zones at the front of the crack. Full article

The number of rubber plantations has increased significantly since 2000, especially in Southeast Asia and China, and their ecological impacts are becoming more evident. A robust rubber supply monitoring system is currently required at both the production and ecological levels. This study used Sentinel-2 multi-rule remote sensing images and a deep learning method to construct a deep learning model that could generate a distribution map of rubber plantations in Danzhou City, Hainan Province, from 2019 to 2024. For biomass modeling, 52 sample plots (27 of which were historical plots) were integrated, and the canopy structure was extracted as an auxiliary variable from the point cloud data generated by an unmanned aerial vehicle survey. Five algorithms, namely Random Forest (RF), Gradient Boosting Decision Tree, Convolutional Neural Network, Back Propagation Neural Network, and Extreme Gradient Boosting, were used to characterize the spatiotemporal changes in rubber plantation biomass and analyze the driving mechanisms. The developed deep learning model was exceptional at identifying rubber plantations (overall accuracy = 91.63%, Kappa = 0.83). The RF model performed the best in terms of biomass prediction (R² = 0.72, RRMSE = 21.48 Mg/ha). Research shows that canopy height as a characteristic factor enhances the explanatory power and stability of the biomass model. However, due to limitations such as sample plot size, image differences, canopy closure degree, and point cloud density, uncertainties in its generalization across years and regions remain. In summary, the proposed framework effectively captures the spatial and temporal dynamics of rubber plantations and estimates their biomass with high accuracy. This study provides a crucial reference for the refined management and ongoing monitoring of rubber plantations. Full article

Silicone rubber from decommissioned composite insulators has become one of the major environmental challenges in the power industry due to its non-degradable nature. Therefore, the recycling and reuse of silicone rubber are of great environmental and economic significance. In this work, a method for preparing silica microspheres based on stepwise pyrolysis combined with post-treatment particle size fractionation is proposed. First, highly spherical silica microspheres were obtained by stepwise pyrolysis. Subsequently, glass fiber membrane filtration and aga-rose gel electrophoresis were employed as post-treatment methods to achieve particle size fractionation and enhanced uniformity. The results indicate that the post-treated silica microspheres exhibit high uniformity, high sphericity, and good dispersibility. This method significantly improves the structural uniformity and microscopic characteristics of the microspheres, making them promising high-value fillers for epoxy resin insulation modification. Comparative analysis with commercial nanosilica used as epoxy fillers shows that the recycled and fractionated silica microspheres achieve comparable improvements in breakdown strength and dielectric performance, confirming their potential for recycling and reuse in high-voltage insulation and electronic packaging applications. Full article

The increase in the viscosity of high-rubber-content asphalt modified with rubber powder at high temperatures leads to processing difficulties and drastic changes in physical properties, which have long been a challenge in the asphalt industry. Although viscosity reducers have shown great potential in addressing these issues, their mechanisms of action in high-rubber-content asphalt modified with rubber powder remain unclear. This study employs diphenyl disulfide (DD) as a viscosity reducer and elucidates its mechanism of action in high-rubber-content asphalt, which includes three stages: (1) dissolution and dispersion in the asphalt matrix; (2) impregnation into the crosslinked network of the rubber powder; and (3) de-crosslinking via active free radicals. By optimizing the pre-impregnation time (12 h), temperature (110 °C), and rubber powder particle size (160–180 µm), the dispersion of DD can be enhanced, thereby improving the processability of high-rubber-content asphalt modified with rubber powder. Compared to untreated asphalt, the optimized conditions result in a significant reduction in the crosslinking density of 50% and a substantial decrease in viscosity at 180 °C. This study provides new insights into the viscosity reduction of high-rubber-content asphalt modified with rubber powder and contributes to a deeper understanding of the mechanisms of viscosity reducers. Full article

As by-products rich in flavonoids and phenolic compounds, onion peels are globally undervalued and often discarded. This study reports the synthesis of carbon quantum dots (CQDs) from onion peels and evaluates their antimicrobial effectiveness against key foodborne pathogens and biofilms on common food contact surfaces, including plastic, stainless steel, and rubber. The CQDs exhibited a quasi-spherical shape with particle sizes ranging from 1.7 to 9.0 nm and contained abundant oxygen- and nitrogen-functional groups, as confirmed by FT-IR and XPS analyses. The CQDs showed significant antimicrobial activity, with minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) against Salmonella typhimurium, Escherichia coli O157: H7, Listeria monocytogenes, and Staphylococcus aureus of 2200/2800 µg/mL, 1400/2000 µg/mL, 1200/1800 µg/mL, and 400/600 µg/mL, respectively. Time-kill assays confirmed these results. In biofilm tests, S. typhimurium formed biofilms more easily than L. monocytogenes. Washing with CQD solution for 5 min reduced biofilm presence by 81.6–91.5% for S. typhimurium and over 74% for L. monocytogenes, with more than 94% reduction after 10 min of treatment (over 94% for S. typhimurium; 95.8–98.8% for L. monocytogenes) across all surfaces, especially on plastic and stainless steel. These findings indicate that onion peel-derived CQDs are promising, eco-friendly agents for disrupting biofilms and turning undervalued waste into valuable products. Full article

In this work, the properties of polymer composites filled with carbon fillers were investigated. The subject of the research was polymeric materials prepared from styrene-butadiene rubber (KER 1500) commonly used in rubber processing, using a conventional sulfur-containing curing system. Two different carbon fillers were applied, namely furnace carbon black (N550) and graphene nanoplatelets (XG G300). These fillers were modified in bulk (during rubber compound preparation) with 4-methyl-1-butylpyridinium bromide (BmPyBr). Modifier would interact with filler’s surface through, e.g., π–π interactions between its pyridine ring and surface of the fillers. The paper highlights the different tendency of the polymer to interact with filler particles of different shapes and sizes, as well as the interactions between filler particles in the presence of an ionic liquid. The rheometric properties of rubber compounds as well as cross-linking density and mechanical properties of SBR composites were studied. Additionally, rheological and viscoelastic properties at the service temperature and the damping properties as a function of deformation of the obtained materials were examined. Full article