Search Results (6,298)

To enhance the seismic performance of existing reinforced concrete (RC) buildings during retrofitting, the study introduces a new type of joint connected by a T-shaped steel plate. Compared with previous similar strengthening methods, this novel structure incorporating a post-installed beam not only effectively improves the mechanical properties of RC columns, but the connectors also further enhance the integrity of the post-installed beam. Low-cycle reversed loading tests on one cast-in-place specimen (RC) and three T-shaped steel plate connection specimens (TRC1–TRC3) were conducted to evaluate failure modes, hysteresis and skeleton curves, and energy dissipation. Results show that the novel joint failure concentrates at beam-end–column steel jacket weld seams and column-side steel plate cracking, while the core-zone concrete remains intact. Compared with RC, the novel joints TRC1–TRC3 exhibit bearing capacity variations of −1.03%~+15.80% and significantly enhanced energy dissipation. The thickness of the beam’s wrapped steel improves the carrying capacity and energy dissipation, whereas the T-shaped connector thickness has limited influence on bearing capacity. ABAQUS parametric analysis indicates that bolt quantity, concrete strength, and connector thickness have limited influence and serve as secondary design factors. These findings provide a theoretical basis for retrofitting existing buildings. Full article

Investigating the mechanics-permeability similarities between natural-like and natural gas-bearing coal–rock specimens provides a theoretical basis for using natural-like specimens as substitutes for natural ones in laboratory simulations of the incubation of coal–rock gas composite dynamic disasters. Based on the similarity between coal and rock in uniaxial compressive strength ratio, natural-like coal–rock specimens were prepared; their mechanics-permeability responses were analyzed through uniaxial and triaxial tests. Both specimen types underwent brittle failure under uniaxial compression, with compressive strength falling between those of coal and rock components but closer to that of coal. Under loading axial stress (LAS), bearing capacity was directly proportional to confining stress (σ₃) for both specimen types—at instability failure, both axial and radial strains increased with σ₃, whereas the axial-to-radial strain ratio decreased; under unloading confining stress (UCS), both specimen types showed reductions in compressive strength and axial strain at peak strength, along with an increase in radial strain, reflecting pronounced dilatancy. Overall, the natural coal–rock specimen (NRCS) and natural-like coal–rock specimen (NLRCS) exhibited similar mechanics-permeability patterns under both uniaxial and triaxial tests, suggesting that natural-like specimens can serve as substitutes for natural ones in laboratory simulations. Full article

The corrosion performance of Al-Mg-Si-Cu laser–arc hybrid welded joints modified by 1.8 wt.% Ni remains poorly clarified. In this study, the corrosion behavior was examined via electrochemical measurements combined with SEM, EDS, and SKPFM. Nickel alloying increased the corrosion potential of the α-Al matrix above that of eutectic Si, thereby suppressing the cathodic role of eutectic Si. Nevertheless, the pronounced potential difference and extensive interfacial area between the Al₃Ni phase and the α-Al matrix promoted localized galvanic corrosion, resulting in chain-like pits along the Al₃Ni phase. This intense galvanic coupling considerably damaged the compactness of the passive film and reduced its resistance. Consequently, the corrosion current density of the welded joint increased significantly from 0.83 μA/cm² to 1.85 μA/cm². These findings suggest that Ni alloying is suitable for welding Al-Mg-Si-Cu alloys in applications where high mechanical performance is essential and corrosion resistance is of secondary importance, such as in body-in-white or chassis load-bearing components. Full article

The tumor microenvironment interacts bidirectionally with systemic host factors, including the gut microbiota. However, it remains unclear whether physical environmental stimuli, such as a hypomagnetic field (HMF), can modulate tumor progression and associated microbial features. In this study, C57BL/6 mice bearing subcutaneous Lewis lung carcinoma (LLC) were maintained under geomagnetic field (GMF) or HMF conditions. We evaluated tumor growth and systemic toxicity, and analyzed fecal samples using 16S rRNA sequencing and short-chain fatty acid (SCFA) profiling. Compared with the GMF control, HMF exposure significantly reduced tumor growth, with an approximately 40% decrease in endpoint tumor volume. No obvious systemic toxicity was detected by monitoring body weight, serum biochemical parameters, and organ histology. HMF exposure altered gut microbial diversity and community composition, with enrichment of several Clostridia-related lineages. Fecal SCFA analysis revealed increased butyrate levels in the HMF group (p = 0.013). Overall, these findings indicate that HMF exposure is linked to reduced LLC tumor growth and changes in gut microbial composition and metabolites. Further studies are needed to clarify the mechanisms underlying these interactions. Full article

This study quantifies five decades (1975–2025) of residential architectural transformation in Delhi (Tier-I) and Patna (Tier-II), India, among middle-income-group households, and evaluates its implications for passive design loss and mechanical cooling dependence. A stratified survey of 1080 middle-income-group (MIG-I and MIG-II) households across six construction decades documents the systematic elimination of passive features: courtyard presence collapsed from 54.44% (Cohort A, 1975–1985) to 1.39% (Cohort C, 2015–2025); load-bearing masonry declined from 47.78% to 7.78%; and houses lacking passive cooling features quadrupled from 10.83% to 40.83%. Correspondingly, households with three or more air conditioning (AC) units rose from 12.78% (Cohort A) to 33.06% (Cohort C). However, 30–35% of households across all cohorts stated that the ‘indoor temperature remains comfortable without AC’, challenging deterministic AC-dependence assumptions. Regional divergence in drivers is evident: globalization dominates in Delhi (59.24%), while lack of traditional awareness dominates in Patna (39.29%), suggesting hierarchical diffusion and indicating a need for differentiated policy responses. Architectural homogenization shows a consistent association with higher AC ownership and electricity consumption, raising concerns about energy insecurity and climate vulnerability. Hybrid design, integrating traditional passive strategies with contemporary spatial needs, offers a pathway toward climate-resilient urban futures. Full article

This study investigates the damage evolution mechanism affecting the fracture-bearing performance of fly ash cement paste under low-temperature curing conditions. Pre-cut cement paste specimens with fly ash contents of 0%, 15%, and 25% were prepared and subjected to both standard curing and low-temperature curing at 5 °C for 28 days. Three-point bending tests combined with acoustic emission (AE) monitoring were conducted to analyze peak flexural load, AE ring count, cumulative energy, RA-AF crack classification, and b-value evolution. Additionally, scanning electron microscopy (SEM) and thermogravimetric analysis (TGA) were employed to characterize micromorphology and relative changes in hydration product content. The results indicate that both fly ash incorporation and low-temperature curing significantly reduce the flexural bearing capacity of pre-notched specimens. Under low-temperature curing, the peak loads of LF15 and LF25 decrease by 34.83% and 47.19%, respectively, compared to LF0. At the same fly ash replacement level, all low-temperature-cured specimens exhibited lower peak loads than those cured under standard conditions. Overall AE activity was reduced in low-temperature-cured specimens, with crack propagation instability occurring at lower load levels. The addition of fly ash shifted the fracture mode toward a tensile-dominated type, whereas low-temperature curing increased the proportion of shear-type AE events. Fly ash incorporation increased the relative content of calcium silicate hydrate (C-S-H) gel and decreased that of calcium hydroxide (CH); however, this did not result in improved peak flexural load. This outcome is attributed to the insufficient reactivity of fly ash at low temperatures, leading to residual unreacted spherical particles, dilution of clinker, and inadequate interfacial bonding, which collectively weaken the continuous load-bearing skeleton of the matrix. This paper establishes a multi-scale interpretation of the damage mechanisms affecting the low-temperature fracture-bearing performance of fly ash cement paste by correlating macroscopic bearing response, AE damage evolution, crack types, and hydration product composition. Full article

This paper presents the research, development, and functional validation of an original rear suspension system designed for hybrid reverse trike vehicles (two guided wheels on the front axle and a twin-tire-driven assembly at the rear). Conventional configurations featuring a single rear wheel exhibit severe limitations regarding lateral stability under critical dynamic regimes and induce roll-induced torsional loading in flexible chain drives. The proposed solution utilizes a twin-tire rear assembly integrated into an articulated suspension mechanism with two degrees of freedom (2 DoF), which reconfigures the geometric stability polygon from a triangle into an isosceles trapezoid. A mathematical model based on tire dynamics and tire slip phenomena demonstrates that introducing a controlled roll stiffness on the rear axle stabilizes the slip angles, ensuring a neutral and predictable steering behavior. Structural validation via finite element analysis (FEA) performed in SOLIDWORKS Simulation on the entire assembly under a conservative combined load scenario (2400 N vertical force shared by the two wheel bearings, 2400 N lateral force, and 1200 N tractive force) indicated a minimum factor of safety of 1.26 on S275N structural steel, confirmed by an eleven-run mesh independence study. Finally, the system’s functionality was experimentally confirmed through the manufacturing and road testing of a full-scale (1:1) demonstrator vehicle powered by an 1129 cc Boxer engine, highlighting a measurable increase in rollover resistance and trouble-free operation of the two-stage chain drive throughout the test program. A numerical evaluation shows that for rear-biased vehicles of the category the proposed axle raises the rollover-related lateral acceleration threshold by up to 54% and replaces the strongly oversteering balance of the single-wheel layout with a near-neutral, tunable one. Full article

Bearing, as a critical component in industrial production, directly dictates equipment performance. Bearing surface defects are typically minute in scale, indistinct at their boundaries, and prone to interference from surface textures and light reflections, thereby posing substantial challenges to detection. This paper proposes a novel deep segmentation network, Bearing-TFUNet, which incorporates the skip connection structure of U-Net to preserve low-level detail information, introduces an enhanced feature pyramid network (UFPN) to bolster multi-scale feature representation capabilities, and integrates a lightweight LE-Transformer for efficient modeling of global contextual information. This triple-fusion mechanism enables the decoder to concurrently integrate skip connection features from the encoder, upsampled features, and multi-scale information furnished by UFPN, facilitating comprehensive feature interaction and fusion. The DWConv-based LE-Transformer attention module effectively augments the model’s capacity for collaborative modeling of local texture details and global dependencies. Experimental results demonstrate that, compared with the baseline U-Net model, Bearing-TFUNet achieves a 12.19% improvement in the Dice coefficient, a 21.94% increase in the IoU metric, and a reduction in Hausdorff Distance from 5.6 to 4.3. Full article

The mechanical performance of CFRP/2024 Al alloy hybrid laminates joined by transverse ultrasonic vibration-assisted riveting (TUVAR) was investigated. The experiments were conducted on a self-developed ultrasonic riveting system with a power of 3000 W and a vibration frequency of 19.8 kHz, covering ultrasonic amplitudes from 0 to 24 μm. Test specimens were fabricated from T300/CFRP laminates, 2024 Al alloy sheets, and 2A10 Al alloy rivets. The influences of ultrasonic amplitudes (12 μm, 16 μm, 20 μm, and 24 μm) on riveting load, driven head geometry, interference, static tensile strength, and cyclic loading behavior were systematically analyzed. The results showed that TUVAR reduced the riveting force and promoted rivet deformation. As the amplitude increased, the driven head diameter increased, and the driven head height decreased, with a maximum reduction of 6.62%. The mean interference generally increased up to 20 μm and then decreased slightly at 24 μm; the relative interference variance coefficient ranged from 0.070 to 0.155 under TUVAR. Static tensile tests showed that the joint strength first increased and then decreased with increasing amplitude, with the highest mean static tensile load obtained at 20 μm. Cyclic tensile tests indicated that load-bearing capacity was improved with increasing amplitude, while the maximum deviation was maintained within 3.5%. These findings demonstrate that TUVAR can enhance both the forming quality and the mechanical performance of CFRP/2024 Al alloy riveted joints, and provide a useful reference for the high-performance joining of composite-metal hybrid structures in aerospace applications. Full article

With the advancement of industrial IoT and artificial intelligence technologies, bearing maintenance is gradually evolving toward predictive maintenance. For large bearings, the internal grease must be replaced promptly once it has deteriorated. As the core lubrication component of such bearings, the suction and discharge device directly determines the efficiency of grease discharge and the operational stability of the bearing. To address the issue of insufficient intake capacity in existing units, this study employs the Herschel–Bulkley non-Newtonian fluid model to analyze intake characteristics and conduct multi-parameter co-optimization, revealing the underlying mechanisms by which vacuum level, grease temperature, and the chamfer structure of the grease inlet pipe influence suction performance. Based on the yield stress and shear thinning characteristics of the grease, the flow equation for the inlet section was derived, and the analytical and CFD results showed consistent trends. With the volumetric flow rate in the inlet section as the optimization objective, a multi-parameter co-optimization of the vacuum level, temperature, and chamfer radius was conducted through orthogonal experiments. The results show that under the optimal parameter combination, the inlet volumetric flow rate was significantly increased, and grease supply stability was markedly improved. The research findings provide a theoretical basis and engineering reference for the design optimization of the suction and discharge device for wind turbine bearings. Full article

A rare-earth (RE)-segregation-assisted route combining mechanical alloying and hot extrusion was used to produce a WE43 alloy with an in situ network-like bimodal structure. Mechanical alloying fragmented and partially dissolved RE-containing phases produced a supersaturated Mg-RE solid solution, and dispersed oxygen-bearing surface films. During the pre-sintering stage before hot extrusion, defect-rich prior powder-particle boundaries (PPBs) acted as preferential sinks for RE solutes, establishing RE-enriched regions before extrusion, while some oxygen-bearing species remained near PPBs and grain boundaries. During subsequent hot extrusion, RE solute drag and pinning by RE-containing precipitates and retained oxides restricted grain-boundary migration near PPBs, whereas rotation-assisted grain coalescence and growth occurred within particle interiors. In the 350—extruded alloy, the relatively coarse and fine grains averaged 299 and 144 nm and occupied 71 and 29 vol.%, while the precipitates averaged 97.1 and 9.2 nm. The 400—extruded alloy achieved a yield strength of 396 MPa, an ultimate tensile strength of 432 MPa, and an elongation of 7.9%. For the 350—extruded alloy, Orowan-type, solid-solution, grain-boundary, and dislocation strengthening contributed approximately 118.5, 116.8, 84, and 67 MPa, respectively, leaving an unresolved residual difference of 63.7 MPa. Coupled RE redistribution and oxide dispersion therefore provide a route to a favorable strength–ductility balance in powder-metallurgy Mg alloys. Full article

To address the challenges in understanding the raceway failure mechanisms of bearings under dynamic radial excitations, this study proposes a vibration evolution analysis method based on multi-source data fusion and a Granger causality test. Firstly, a vertical bearing vibration test bench that can simulate the dynamic excitation in engineering practice is built, and the bearing acceleration, inner ring displacement and cage data are collected at the same time. Subsequently, the evolution law and correlation relationship of bearing vibration signals during the expansion process of bearing raceway damage were studied. Based on this, a multi-source vibration data fusion method was proposed, and the effectiveness of different data fusion schemes in characterizing raceway damage expansion was compared. Finally, the Granger causality test was applied to analyze the causal relationship between the evolution of various vibration behaviors during the damage propagation process. Research results demonstrate that under complex loading conditions during sustained operation, the “False Brinelling” indentation gradually develops into raceway surface damage. The vibration behavior of bearings exhibits distinct stage-specific characteristics under dynamic radial excitations. Notably, variations in vibration behavior amplitude and transition timing between different operational phases demonstrate significant discrepancies. Significant alterations in causal relationships between vibration behaviors were observed throughout different degradation phases. The combined approach proposed in this paper, encompassing complex load simulation, multi-source data fusion, and causal analysis, offers a new understanding of the raceway failure mechanism of bearings under real-world operating conditions. Full article

Skeletal muscle is a continuously load-bearing tissue whose growth, repair, and age-related decline are governed by mechanical signals; failure of this mechano-regulation underlies disuse atrophy and sarcopenia. Piezo1, a mechanically activated cation channel, has emerged as a tractable transducer of these signals in muscle, contributing to satellite-cell quiescence and senescence, regenerative division, myoblast fusion, and the response to loading and unloading. In parallel, the myogenic noncoding RNA program is among the best defined in any lineage, with myomiRs miR-1/133/206, the long noncoding RNA LINC-MD1, and the circular RNA circ-ZNF609 being established regulators of the proliferation-to-differentiation transition. These layers are linked because Piezo1-evoked calcium influx feeds the RhoA/ROCK-actin-MRTFA-SRF and YAP/TAZ axis that drives myogenic transcription, yet no direct coupling between Piezo1 and noncoding RNAs has been demonstrated in skeletal myocytes. Drawing on validated precedents from vascular, cardiac, and tendon tissues, this review consolidates the two pillars, frames their convergence as a testable question, distinguishes validated relationships from hypotheses, and proposes three falsifiable predictions using an unbiased candidate selection strategy. The contribution of this review is this testable framework rather than any specific candidate list. Mechanically tunable noncoding RNAs may thus represent an underexplored node for counteracting disuse atrophy and sarcopenia. Full article

To improve the bending resistance and support the domestic development of deepwater subsea wellhead equipment, a three-dimensional finite element model (FEM) of the SXW-15 subsea wellhead system was established in ANSYS Workbench considering contact nonlinearity and rigid-locking mechanisms. Based on representative deepwater drilling and completion conditions, the effects of the friction coefficient, locking preload, blowout preventer (BOP)/lower marine riser package (LMRP) top load, casing hanger internal pressure, and tubing load on the ultimate bending capacity of the system were systematically investigated. The results show that the bending capacity increases with increasing friction coefficient and locking preload, whereas it decreases with increasing top load and tubing weight. The internal pressure of the casing hanger exhibits a pronounced nonlinear influence on the bending resistance, and the maximum bending capacity occurs at an internal pressure of approximately 4000 psi. Based on the mechanical analysis, several innovative designs were proposed, including a layered load-bearing structure, a gravity-set metal sealing assembly, a self-supporting rigid-locking mechanism, and an integrated multifunctional tool system, aiming to improve load-transfer efficiency, connection stiffness, and high-pressure sealing stability. Land-based testing and offshore field applications were subsequently conducted to verify the engineering applicability of the system. The subsea wellhead system with innovative designs maintained satisfactory structural integrity and sealing reliability under conditions of 15,000 psi internal pressure and 12.7 million lb axial load. Good agreement was obtained between finite element predictions and field test results. The present study provides theoretical support and guidance for the structural designs and engineering applications of deepwater subsea wellhead systems. Full article

Ovarian cancer treatment remains challenging due to aggressive metastasis and the complex tumor microenvironment (TME). Solanum nigrum L. (SN), a berry-bearing plant rich in bioactive phytochemicals, offers promising multi-target anticancer potential. This study elucidated the systemic molecular mechanisms of SN fractions against ovarian cancer by integrating network pharmacology, molecular docking, and in vitro models. In silico analyses and molecular docking identified apoptosis, metastasis-related pathways, and NF-κB (RELA) as core targets. For in vitro validation, butanol (SNBT) and methylene chloride (SNMC) fractions of SN were evaluated in SKOV3 cells. SNBT significantly induced caspase-3-dependent apoptosis, while SNMC effectively suppressed cancer cell migration and invasion without cytotoxicity. Furthermore, both fractions markedly downregulated phosphorylated AKT and NF-κB, experimentally confirming the suppression of the AKT/NF-κB signaling axis. Crucially, in a tumor-associated macrophage co-culture model, SNMC attenuated the pro-metastatic TME by reducing MMP2, MMP9, and VEGF secretion. Conclusively, SN exerts potent anticancer effects through distinct fractional activities, such as driving apoptosis and blocking metastasis, mediated via AKT/NF-κB inhibition and TME remodeling. These findings highlight SN-derived fractions as promising multi-target therapeutic candidates against ovarian cancer. Full article