Search Results (11,585)

In heavy-haul railway systems, effective empty railcar distribution (ERD) can optimize composition planning and meet empty railcar requirements (ERRs) at all loading ends, thereby improving the efficiency of train operations. To solve practical challenges such as the imbalanced supply–demand of empty trains, redundant loading and unloading cycles, and prolonged waiting times, this study establishes a multi-objective and 0-1 integer programming model for ERD at the loading end of a heavy-haul railway. The model can simultaneously maximize the fulfilment of all ERRs, minimize the ERD delay time, and reduce the waiting time in the heavy-train combination problem under complex constraints, including the passing capacity of sections, combination capacity of stations, and ERR at the loading end. While traditional optimization methods such as mathematical programming or heuristic algorithms partially address these issues, they are ineffective under dynamic constraints and state-space explosion. Furthermore, traditional reinforcement learning-based methods, such as Q-learning, exhibit limitations in railway scheduling due to the state-space explosion problem and inadequate model generalization. To overcome these limitations, this study proposes an innovative framework; the ERD at the loading end of the heavy-haul railway is formalized as a Markov decision process and optimized using deep Q-network (DQN) reinforcement learning. In addition, this study proposes an experience data fusion mechanism that integrates the empirical rules of the dispatchers through a modular architecture, achieving real-time constraint compliance while maintaining scalability for practical implementation. The NSGA-II genetic algorithm for multi-objective problems is used in this study to evaluate the performance of the DQN algorithm. The experimental results demonstrate that the DQN algorithm can fully meet ERRs with zero delay and produce optimal schemes for train combinations. Meanwhile, NSGA-II presents superior performance in minimizing the combination waiting time and same-destination train combinations. Meanwhile, the DQN algorithm can identify superior ERD strategies in the expanded-action and state spaces, enabling the effective handling of complex constraint-based ERD. Full article

The increasing demand for high-performance and multifunctional polymer materials has driven interest in improving the mechanical properties of polymer components produced through additive manufacturing. This study aims to systematically investigate and comparatively evaluate the effects of low-content nanofiller incorporation on the structural, thermal, and mechanical performance of PLA-based materials produced via fused deposition modeling (FDM), with a focus on identifying filler-dependent behavior under different loading conditions. In this study, polylactic acid (PLA) composites reinforced with 0.5 wt.% graphene (Gr) and 0.5 wt.% silver (Ag) nanoparticles, added separately, were produced using fused deposition modeling (FDM) and comparatively investigated. Each nanofiller was incorporated individually into PLA-based filaments, and standard test specimens were fabricated via 3D printing. Structural, thermal, and mechanical properties were evaluated using tensile, compressive, and three-point bending tests, along with SEM, EDS, XRD, FTIR, DSC, and TGA analyses. The results showed that pure PLA exhibited typical brittle behavior and a single-stage thermal degradation profile. The tensile strength of pure PLA was 41.93 MPa, and the flexural strength was 70.76 MPa. The addition of 0.5 wt.% graphene led to noticeable improvements, particularly in flexural properties, while only a minimal (almost negligible) increase was observed in tensile strength, with tensile strength increasing to 42.24 MPa (+0.74%) and flexural strength increasing to 110.78 MPa (+56.6%). In contrast, 0.5 wt.% Ag exhibited mixed and load-dependent mechanical behavior, with slight improvements in flexural strength but reductions in tensile and compressive properties, where tensile strength decreased to 22.13 MPa (−47.2%) while flexural strength increased to 112.06 MPa (+58.3%). Structural and thermal analyses indicated that both nanofillers did not significantly alter the PLA matrix chemically, while contributing to controlled changes in material properties primarily through physical interactions. The novelty of this work lies in the comparative evaluation of graphene and silver nanoparticle reinforcement at a fixed low loading level within FDM-processed PLA, combined with a comprehensive and correlated analysis of mechanical, structural, and thermal behavior on the same specimen sets, enabling a clearer understanding of filler-dependent performance mechanisms in additively manufactured nanocomposites. Overall, it was concluded that low-rate nanofiller additions, when properly dispersed, may lead to selective improvements in the performance of PLA-based composites depending on filler type and loading mode, and show potential for advanced engineering applications such as lightweight structural components, functional sensors, and additive-manufactured parts requiring tailored mechanical performance and multifunctionality. Full article

To address the demand for lightweight, high-performance Al-Si-Mg alloys in aerospace and automotive industries, this work proposes a novel synergistic strengthening strategy by combining rare-earth Y microalloying and in situ synthesized ZrB₂ nanoparticles to construct a hybrid reinforcement architecture. The effects of Y-ZrB₂ additions on the microstructure, crystallographic orientation evolution, and mechanical properties of Al-Si-Mg alloys were systematically investigated via XRD, SEM, EBSD, and tensile/hardness tests. Results show that compared with the base alloy and single-modified alloys, the co-addition of Y and ZrB₂ simultaneously enhances mechanical properties and optimizes grain structure. The optimal comprehensive performance is achieved at 0.3 wt.% Y + 2 wt.% ZrB₂ after T6 heat treatment, with ultimate tensile strength of 332.87 MPa, yield strength of 271.35 MPa, elongation of 16.24%, and Vickers hardness of 153.9 HV. Phase analysis and SEM-EDS confirm a synergistic coupling relationship between Y-rich phases and ZrB₂ nanoparticles. EBSD characterization reveals that Y-ZrB₂ modification has negligible effect on the morphology and crystallographic orientation stability of primary α-Al grains, but effectively regulates the lattice rotation, texture redistribution, and growth behavior of eutectic Si. At the optimal composition, the fraction of high-angle grain boundaries (HAGBs) reaches a maximum of 34.3%. Furthermore, the synergistic effect significantly increases the geometrically necessary dislocation (GND) density and reduces the Schmid factor of the dominant {111}⟨110⟩ slip system, thus enhancing dislocation strengthening and plastic deformation resistance. This work clarifies the intrinsic strength-ductility synergy mechanism of Y-ZrB₂ co-modified Al-Si-Mg alloys, paving a new pathway for the development of advanced lightweight aluminum alloys. Full article

Driven by the growing demand for functional textiles featuring excellent waterproofness, moisture permeability and mechanical robustness in outdoor sportswear, medical protection and technical apparel, traditional pongee—despite its desirable softness, high wrinkle resistance and good stability as an ideal substrate fabric—is severely restricted in further application by its intrinsically poor hydrostatic pressure resistance in extremely wet environments. Accordingly, we developed a modified waterborne polyurethane (WPU) coating for pongee substrates to fabricate functional textiles that maintain high hydrostatic pressure resistance while possessing good mechanical properties and increased UV absorption. In this study, by using the sol–gel method, an amorphous silicon dioxide (SiO₂) coating layer was constructed on the surface of titanium dioxide (TiO₂) particles, forming silica-modified titania particles (SiO₂/TiO₂). These SiO₂-modified particles were subsequently physically blended with an anionic waterborne polyurethane system that had been previously modified with a polyester-type modifier A to enhance its hydrostatic pressure resistance. The resulting composite coating was designed to combine the high hydrostatic pressure resistance inherited from the modified WPU matrix, the mechanical reinforcement and increased UV absorption contributed by SiO₂/TiO₂, and satisfactory water repellency on fabric substrates. The results indicate that the incorporation of an appropriate amount of modifier A into the prepolymer system significantly enhances hydrostatic pressure resistance while maintaining high elongation at break. At a SiO₂/TiO₂ loading of 0.2 wt%, the composite film exhibits optimal comprehensive performance, characterized by superior mechanical properties, low water absorption, and static water contact angles exceeding 100° for coated fabrics. SiO₂/TiO₂ composite WPU coatings substantially improve hydrostatic pressure resistance across various fabrics, with 380T polyester taffeta demonstrating the best performance. This resistance remains remarkably stable after standard washing, indicating excellent wash fastness and practical applicability. Full article

This study was conducted to explore how varying the concentration of nano-La₂O₃ particles in the plating bath influences the morphology, constitution, and corrosion resistance of Ni-B composite coatings deposited on N80 carbon steel via electroless plating. The novelty of this work lies in the systematic investigation on the co-deposition behavior and grain refinement mechanism of nano-La₂O₃ in electroless Ni-B system, which has been rarely reported in previous studies. The microstructure and chemical composition of the coatings were characterized through a combination of SEM, EDS, XPS and XRD analyses. SEM confirmed that a dense Ni-B/La₂O₃ composite coating was formed, with a uniform thickness of approximately 10 μm, and the nano-La₂O₃ particles were evenly distributed. XPS analysis verified the presence of B, C, O, Ni and La, while XRD analysis revealed a refinement in crystalline size due to the addition of the nanoparticles. The corrosion resistance enhancement mechanism is attributed to the triple synergistic effect: nano-La₂O₃ pins grain boundaries and refines Ni-B grains to the minimum average size of 12.943 nm at the optimal concentration of 8 g·L⁻¹; the refined grain structure promotes the formation of a continuous and dense Ni(OH)₂ passive film; the uniformly dispersed nanoparticles act as physical barriers to block the penetration of corrosive media. Electrochemical measurements demonstrated that this coating exhibited outstanding anti-corrosion performance, as confirmed by a remarkably positive corrosion potential (E_corr = −0.37189 V) and a minimal corrosion current density (I_corr = 3.7524 μA/cm²). The results conclusively show that nano-La₂O₃ reinforcement effectively enhances the corrosion protection performance of electroless Ni-B alloy coatings. Full article

Optimizing the structural stability of foundations is challenging in modern geotechnical engineering. This study investigated the mechanism of geocell-reinforced foundations through discrete element modeling based on transparent soil model tests. A three-dimensional particle flow code (PFC^3D) model was developed to investigate the micromechanical soil–geocell interactions in both unreinforced and geocell-reinforced foundations under strip loading. Particle displacement, contact force distribution, and structural deformation within the foundation system were analyzed to quantify the performance of geocell reinforcement. The results show that geocell inclusion enhances structural performance by 2.1 times compared to an unreinforced foundation, increasing the bearing capacity from 60.6 to 126.8 kPa at a defined bearing capacity criterion. The geocell walls act as rigid physical boundaries that microscopically intercept the lateral migration and horizontal extrusion of soil particles. The kinematic trajectories of soil particles beneath the loading plate are forced into a downward realignment, decreasing the displacement vector rotation angle from 42° in the unreinforced soil to 27° in the reinforced soil and effectively mitigating the heave of adjacent surfaces. Furthermore, the quasi-rigid three-dimensional network completely interrupts the continuous steep contact force chains inherent in unreinforced foundations. Concentrated vertical stresses are converted into horizontal components through interfacial friction and mechanical interlocking, resulting in the lateral redistribution of the applied load by a distance of approximately 0.06 m. The geocell–soil composite considered as a flexible raft foundation extends load dispersion and reduces average subsoil pressure. A coupled tension and compression stress state in the horizontal plane is developed within the geocell structure. Forces are channeled along rigid paths by elevated bending moments and stress concentrations at the cell junctions. These findings provide micromechanical insights into the performance of geocell-reinforced-foundation systems. Full article

The application of continuous carbon fiber (CCF) can reinforce the mechanical properties of 3D-printed parts, but the effect of reinforcement layer distribution on composite performance remains unclear. This study investigates the effect of concentrated and separated distributions of CCF layers with different numbers of reinforcement layers. Tensile and flexural tests are conducted in accordance with ASTM D5083 and ASTM D790, respectively. Under the conditions of a solid-filled matrix (Onyx) and 0° CCF deposition, both concentrated and separated CCF layers improve several mechanical properties. Compared with pure Onyx, one-layer CCF increases the tensile modulus by about six times and more than doubles the tensile strength. Increasing the CCF volume leads to further increases in these properties. With concentrated three-layer CCF, the tensile modulus and tensile strength reach 7.153 ± 0.090 GPa and 109.045 ± 5.124 MPa, respectively. For flexural properties, separated two- and three-layer CCFs significantly improve the tangent modulus of elasticity from 0.467 ± 0.106 GPa for pure Onyx to 2.246 ± 0.333 GPa and 3.394 ± 0.081 GPa, respectively. This study also compares the tensile and flexural strength-to-weight ratio of all specimen groups and analyzes the failure mechanisms based on macroscopic fracture appearance. The results can provide guidance for selecting appropriate CCF layer distribution strategies to reinforce composites in different applications. Full article

AlCoCrFeNi high-entropy alloy coatings reinforced with different TiN contents (2 wt.%, 4 wt.%, and 6 wt.%) were fabricated on 304 stainless steel by laser cladding. The effects of TiN addition on the microstructure, hardness, friction behavior, and wear resistance of the coatings were investigated. Dry reciprocating sliding tests were conducted under a load of 10 N, a frequency of 5 Hz, a stroke length of 5 mm, and a duration of 20 min using GCr15 bearing steel balls as the counterpart. The results showed that the 2 wt.% TiN coating exhibited the best tribological performance within the investigated composition range, with a microhardness of 579.6 HV_0.5, a relatively low and stable friction coefficient of approximately 0.30–0.35, and a wear rate of 2.9 × 10⁻⁴ mm³/(N·m). When the TiN content increased to 4 wt.% and 6 wt.%, the wear resistance decreased, which was mainly associated with particle agglomeration, local stress concentration, and brittle spalling. These results indicate that appropriate TiN addition can improve the load-bearing capacity and wear resistance of laser-cladded AlCoCrFeNi coatings, providing a potential surface-strengthening strategy for 304 stainless steel components under dry sliding conditions. Full article

Particulate-reinforced polymer composites (PRPCs) are susceptible to cracking under tensile loading, severely limiting their service life. Here, we propose a pressure-gradient-driven infiltration method that rapidly repairs narrow (<10 μm) cracks in a highly filled PRPC (95 wt.% BaSO₄/5 wt.% fluororubber). Microstructural evidence confirms that the adhesive completely fills the tortuous crack and forms a continuous adhesive–matrix interface capable of supporting load transfer. Semi-circular bend (SCB) testing demonstrates a substantially higher peak load and increased apparent structural stiffness after repair under the present semi-circular bend configuration, indicating apparent mechanical enhancement beyond simple load-bearing recovery. Digital image correlation (DIC) and fracture morphology show that repair suppresses notch-tip strain localization, reduces the strain concentration factor, shifts the failure-controlling zone away from the original notch tip, and deflects the crack propagation path. Phase-field simulations further show that the post-repair load-bearing capacity is governed by the adhesive–matrix interfacial strength; once this strength approaches or exceeds the tensile strength of the intact PRPC (~8.3 MPa), the repaired crack path is stabilized, enabling peak-load enhancement while suppressing damage localization along the original crack path and shifting failure to adjacent weaker regions. Overall, this work establishes a promising crack repair approach for highly filled PRPCs, while the underlying interface-controlled mechanism provides guidance for adhesive selection and repair design. Full article

In this study, Fe₇₀Ni₃₀ metal was deposited onto continuous glass fiber composites via magnetron sputtering, followed by surface coating with SiO₂. The effects of key process parameters-including Fe₇₀Ni₃₀ sputtering duration (2, 5, 10, 20, and 30 min) and SiO₂ surface coating-on the electromagnetic properties and microwave absorption performance of the materials were systematically investigated. Scanning electron microscopy (SEM) characterization revealed that as sputtering time increased, the metal coating evolved from discrete small particles into a continuous film. Cross-sectional SEM analysis further demonstrated the formation of a bilayer structure after SiO₂ introduction. X-ray diffraction (XRD) patterns confirmed the presence of diffraction peaks corresponding to the Fe₇₀Ni₃₀ alloy solid solution. Electromagnetic parameter measurements indicated that the influence of sputtering time on electromagnetic properties was primarily pronounced during the metal layer growth stage; once a continuous film was formed, the variation in electromagnetic parameters diminished. Concurrently, the SiO₂ coating exhibited a significant regulatory effect on dielectric parameters. Reflection coefficient calculations showed that the optimal absorption thickness for the single-layer material ranged from 2.5 to 3.0 mm, with the absorption peak shifting toward lower frequencies as thickness increased. However, the effective absorption bandwidth (EAB) was only 3–5 GHz, failing to meet wideband requirements. In contrast, the three-layer composite structure (total thickness: 3.8 mm) optimized via genetic algorithm achieved impedance gradient and loss synergy, expanding the EBW (R < −10 dB) from 4.8 GHz (single layer) to 10 GHz (8–18.0 GHz)-a substantial improvement over the single-layer configuration. This work provides experimental evidence and technical support for the structural design and process optimization of lightweight, high-efficiency, wideband microwave-absorbing materials. Full article

Strong seismic waves induced by drill-and-blast tunnel excavation threaten the structural integrity of adjacent existing tunnels; however, prevailing safety evaluation methods mostly simplify tunnel linings as homogeneous continua, failing to accurately characterize the meso-scale uncoordinated dynamic response between rebar and concrete under blast impact. To fill this research gap, a 1:1 full-scale separated three-dimensional finite element model of reinforced concrete composite linings was established using the LS-DYNA explicit dynamic numerical algorithm, which was verified by previous 1:25 scaled physical model tests. This study systematically quantifies the spatiotemporal evolution of lining dynamic responses under two core parameters—tunnel clear distance (10 m to 60 m) and single-delay detonating charge quantity (10.8 kg to 28.8 kg)—to validate the response differences between materials. It is abstracted that the structural failure is dominated by axial tensile stress, with the embedded rebar being significantly more sensitive to internal stress surges (reaching 3.5 times the peak stress of concrete), while the concrete is more sensitive to particle vibration velocity amplification, a mismatch that is particularly acute within a 30 m clear distance. This study highlights the severe interfacial stress gradient between rebar and concrete, providing an indirect but critical indicator for the potential risk of interface debonding under adjacent blasting, and offers a quantitative theoretical basis for extending safety assessments from macro-surface vibration control to refined meso-scale internal stress monitoring. Full article

With the rapid urbanization of China, environmental risks posed by informal landfills, particularly those dominated by agricultural waste, are an urgent yet understudied concern. This study systematically monitored groundwater quality surrounding five typical informal agricultural waste landfills in a coastal Chinese city. Eight major pollutants were analyzed using pollution index evaluation, the health risk model and multivariate statistical methods. The results indicate one landfill as a high-priority concern, exhibiting a combined multi-index pollution pattern with an exceedance rate of 87.5%, where NO₃⁻-N, F⁻, COD_Mn, and total hardness are the dominant indicators. Another landfill showed high background levels and anthropogenic impacts. Total non-carcinogenic risk of all landfills is below 1 (negligible). Children face approximately twice the health risk of adults. The exposure risk through drinking water ingestion is three orders of magnitude higher than that from dermal contact, with NO₃⁻-N contributing >90% of the total risk. Groundwater deterioration is primarily affected by geological conditions and seawater intrusion (52.31%), followed by agricultural activities and soil characteristics. Given these findings, priority attention should be directed to nitrogen-driven landfill and multi-index composite pollution landfill, with reinforced source tracing and control of NO₃⁻-N, alongside long-term monitoring for regional groundwater protection. Full article

This study investigates the effect of waste cement dust (CD) and rock wool (RW) inorganic fiber on the tribological performance of brake friction composite materials. Five formulations were fabricated by varying CD from 65 to 45 wt.% and RW from 5 to 25 wt.% and evaluated for tribological properties on a Chase friction testing machine in accordance with IS 2742 test procedures. The results show that composites containing higher CD and lower RW exhibited higher coefficients of friction, lower friction variability, and improved fade resistance. In contrast, composites containing higher RW and lower CD showed improved recovery characteristics and substantially enhanced wear resistance. The performance coefficient of friction decreased from about 0.521 to 0.442 as the formulation shifted from CD-rich to RW-rich compositions, while the variability coefficient increased from about 0.364 to 0.516. The highest wear was recorded for the composite containing 65 wt.% CD and 5 wt.% RW inorganic fiber, whereas the lowest friction fluctuations were obtained for the composite containing 55 wt.% CD and 15 wt.% RW inorganic fiber. Finally, a simple ranking process-based decision-making technique was employed to evaluate the overall performance of all the composites, suggesting 55 wt.% CD as the optimal content. These findings confirm the potential of waste CD as a viable functional constituent in brake friction composites when combined with RW inorganic fiber in an optimized manner. Full article

The study investigated the tensile strength and elongation properties of abaca fiber-reinforced polymer (AFRP) composites after varying durations of seawater soaking, with a focus on their potential for reinforcing fiber-optic cables. It aims to bridge industrial technology education, experiential learning, and green technology by evaluating abaca fiber as a sustainable alternative to synthetic aramid yarn. Conducted at Caraga State University, Cabadbaran Campus (CSUCC), the research utilized a quasi-experimental product development design involving industrial technology students and instructors. Tensile strength testing and comparative analysis were performed on abaca fiber samples (A, B, and C) subjected to different seawater soaking durations. Results show that soaking time significantly affects the fiber strength, with Sample A achieving the highest tensile strength (5631.5 MPa) and Sample C the lowest (1679.8 MPa). Findings indicate that prolonged exposure to seawater weakens abaca fiber, emphasizing the need for controlled treatment to optimize its industrial applications. This study emphasizes the importance of hands-on learning in industrial technology education, promoting critical thinking and technical skills while underscoring sustainability. The research advocates for eco-friendly materials in industrial applications and highlights the potential of abaca fiber composites. Future studies should investigate pre-treatment methods to enhance fiber durability, assess the long-term environmental performance, and conduct large-scale pilot testing to evaluate commercial viability. By integrating sustainable innovations into industrial technology education, this study contributes to advancing natural fiber composites for manufacturing and telecommunications infrastructure. Full article

The emergence of a novel crumb rubber (CR)/SBS-polymerized pellet has simplified the complex preparation process of composite-modified asphalt. However, the effectiveness of CR/SBS-polymerized pellets in improving asphalt performance has not been confirmed. This study mainly investigated the performance and reinforcement mechanism of polymerized pellet-modified asphalt. First, polymerized pellet-modified asphalt samples with different contents (10%, 20%, 30% and 40% of the asphalt mass) were prepared. Then, the physical properties, rheological behavior, thermal stability, and aging resistance of the pellet-modified asphalt samples were systematically evaluated, using both base asphalt and a commercially available styrene–butadiene–styrene triblock copolymer (SBS)-modified asphalt as control groups for comparison. Finally, the modification mechanism was explored through Fourier transform infrared spectroscopy (FTIR) and fluorescence microscopy (FM). The findings demonstrated that the incorporation of polymerized pellets could effectively decrease the penetration, elevate the softening point, and enhance the viscosity of asphalt. In addition, the high- and low-temperature performance, as well as the aging resistance of the modified asphalt, were significantly improved. These enhancing effects became more pronounced with increasing modifier content. The performance of SBS-modified asphalt is between 20% pellets MA and 30% pellets MA. The pyrolysis temperature range of all asphalt samples is 220 °C~500 °C, and infrared spectroscopy indicated that CR/SBS pellet-modified asphalt is mainly a physical mixing process. This work provides a scientific basis for further engineering applications of CR/SBS pellets. Full article