Search Results (289)

Grounding connectors critically influence the safety and long-term reliability of earthing systems through coupled electro-thermal, mechanical, and corrosion behaviors, yet no standardized quantitative framework exists for jointly evaluating these performance dimensions across diverse deployment scenarios. This study introduces a unified multi-criteria evaluation framework applied to six grounding connector configurations spanning four alloy families and three joining technologies. Electro-thermal response was characterized by coupled finite element simulations (0–100 A), mechanical reliability by quasi-static tensile testing (n = 10 per configuration), and corrosion durability by accelerated salt-spray exposure with image-based corroded area fraction quantification. Performance metrics were normalized and aggregated using equal-weight, Analytic Hierarchy Process, and Shannon entropy weighting schemes, with the Technique for Order of Preference by Similarity to Ideal Solution applied for multi-scenario ranking. One-way analysis of variance confirmed statistically significant effects of connector type on tensile performance (F(5, 54) = 3154.90, p < 0.001). The exothermic welded joint achieved the highest mean ultimate tensile load (61.5 ± 1.5 kN), while copper mechanical connectors exhibited the lowest steady-state temperature rise (~2 K above ambient at 100 A). Compression-crimped connectors ranked first under both equal and Analytic Hierarchy Process weighting (closeness coefficients 0.737 and 0.807, respectively), while stainless steel connectors ranked first under corrosion-critical deployment scenarios. Scenario-weighted analyses demonstrate that the optimal material–process combination shifts with environmental severity, current duty, and mechanical demand, providing a reproducible, evidence-based basis for context-dependent connector specification. Full article

Traditional fixed-tilt photovoltaic (PV) support structures commonly employ inclined beams, double columns, and diagonal braces to resist and transfer horizontal loads. However, this conventional design is characterized by an excessive number of structural components, elevated steel consumption, and suboptimal installation efficiency. To address these limitations, this study proposes a novel unbraced double-column PV support system incorporating hat-shaped inclined beams and T-shaped connectors. The proposed configuration eliminates diagonal bracing while maintaining structural integrity through an efficient load-transfer mechanism, thereby achieving improved standardization, reduced steel consumption, and enhanced constructability. The structural performance of the proposed system was rigorously evaluated through full-scale load-bearing experiments and comprehensive finite element analysis (FEA). The global response, including ultimate load capacity, failure modes, and deformation characteristics, was comprehensively evaluated. The results demonstrate that the proposed system exhibits favorable mechanical behavior and sufficient load-carrying capacity under combined loading conditions. Furthermore, the finite element model was validated against experimental results, showing good agreement in terms of stiffness, deformation patterns, and ultimate response, thereby confirming its reliability for structural analysis. Full article

Achieving precise docking, reliable locking and damage-free emergency unlocking under complex ocean current conditions remains a key challenge for deep-water multi-way quick connectors (MQCs). This study proposes a novel MQC prototype characterised by a tiered tolerance guidance mechanism, an innovative L-shaped spatial helical cam locking system, and a real-time visual attitude indicator. Using Ansys 2023 R2 and its tools, the safe operating limits were determined through explicit non-linear finite element collision analysis. The results demonstrate that, under a controlled docking speed of 10 mm/s, the hierarchical guidance mechanism successfully accommodated extreme initial misalignments (25 mm lateral offset, 5° horizontal rotation and 15° axial rotation), whilst keeping the peak collision stress within the elastic limit. Furthermore, the L-shaped locking guide was analysed using a fifth-order polynomial motion law and a macro-micro elastoplastic Hertzian contact mechanics model, effectively eliminating rigid-flexible impact forces. Under extreme separation loads of 10,000 psi, the maximum equivalent plastic strain at the base of the locking shaft was strictly controlled at 0.00926. This is well below the failure threshold of 0.0865 specified by ASME, providing a substantial safety margin and completely preventing local yielding. Crucially, the emergency release strategy based on precision locating pins was validated through full-scale prototype testing. Destructive tests conducted under simulated severe jamming conditions demonstrated clean, damage-free disengagement under shear torques ranging from 2100 Nm to 2200 Nm. This threshold ensures that accidental triggering will absolutely not occur during routine operations (1400 Nm) and establishes a safe underwater robotic (ROV) operating speed of ≤4 r/min. This study provides a robust theoretical framework and empirical data for the future design of yield-resistant subsea connectors and safe emergency recovery. Full article

The contact performance of automotive airbag electrical connectors directly affects the stable conduction of the initiator circuit, yet sufficient failure data are difficult to obtain for such long-life safety-critical components. This study develops a degradation model for connectors with stainless-steel pins, beryllium-bronze sockets, and Ni/Au composite coatings, using the contact resistance increment as the degradation measure. Considering the accumulation of oxidation corrosion products under thermal stress, as well as the local film rupture and re-oxidation induced by fretting wear under combined temperature-vibration stress, a nonlinear time scale t^α is introduced to describe the nonlinear growth of contact resistance. A random-drift nonlinear Wiener process is then constructed: the diffusion term represents local fluctuations within each sample trajectory, while the random drift rate captures growth-rate differences among samples. Parameter estimation was performed using degradation data obtained from 160 °C high-temperature and 160 °C temperature-vibration accelerated degradation tests. The estimation results show that the stress-class-specific time-scale model better reflects the different degradation mechanisms than a common time-scale model, and that the temperature-vibration group exhibits higher resistance growth and stronger trajectory fluctuations. Model diagnostics support the description of the main increment distribution and sample-to-sample differences, while EDS and XPS results provide supplementary evidence for oxidation-related surface composition changes and coating-state evolution. Full article

Tooth-supported fixed partial dentures (FPDs) exhibit complex biomechanical behaviour because occlusal loads are transferred through the periodontal ligament (PDL) and heterogeneous mandibular bone. This pilot study aimed to develop a patient-specific NURBS-based finite element analysis (FEA) workflow for anatomically realistic mandibular reconstruction and to evaluate the biomechanical effect of geometric simplification in tooth-supported FPD simulations. Cone beam computed tomography data from a single subject were segmented and reconstructed into a layered three-dimensional model of the mandible and dentition, including cortical bone, cancellous bone, teeth, and PDL. A high-fidelity reference model (V0) and four simplified variants (V1–V4) were analysed under static 500 N loads applied at 0° and 30°. The reference model yielded a maximum von Mises stress of 507 MPa and a peak displacement of 0.74 mm, with stress concentrations consistently localised at the retainer–pontic connector region. Inclusion of the PDL markedly affected the mechanical response, doubling denture displacement in simplified comparative models. Among the simplified configurations, V4, which preserved cortical morphology and PDL representation while omitting detailed trabecular architecture, showed the closest agreement with the reference model, with mean deviations of 6.1% and 5.8% under the two loading conditions, respectively. These findings suggest that patient-specific NURBS–FEA modelling provides a robust framework for biomechanical assessment of tooth-supported FPDs, while controlled simplification may improve computational efficiency without substantially compromising accuracy under static loading conditions. Full article

This study experimentally investigates the structural behavior of hexagonal- and square-shaped composite specimens subjected to vertical compression, vertical tension, and diagonal tension loading. The specimens were fabricated using four- and six-layer alkali-resistant (AR) glass textile reinforcements embedded in a modified cementitious mortar via pull, pour, and roll manufacturing techniques. The mechanical performance of polyvinyl alcohol (PVA) fiber-reinforced composite connectors and steel clamp-type elements was also evaluated at the joints of hexagonal specimens under vertical tension and lateral shear loading. The results show that increasing the number of textile layers significantly enhances structural performance. A 50% increase in textile layers improved load-carrying capacity by up to 56% in compression, 104% in tension, and 216% in diagonal tension. Corresponding increases of approximately 20–42% in ductility and up to 266% in energy dissipation capacity were observed. No failure occurred in the connecting elements, confirming their adequate stiffness, strength, and ductility. In addition, validated three-dimensional finite element models were developed to simulate the response of the hexagonal specimens. Overall, the proposed system demonstrates strong potential for applications such as infill walls, cladding, and sandwich panels due to its favorable strength, ductility, and energy absorption capacity. Full article

The paper presents an innovative approach to producing structural connectors for bamboo constructions using recycled plastic. This solution enhances the sustainability of bamboo structures while simultaneously promoting the valorization of plastics waste. The aim is to conduct a preliminary investigation in the possible use of high-density polyethylene (HDPE) as a structural material. Two connectors’ geometries have been developed, both specifically devised for bamboo truss systems: a paddle-shaped design and an oval-shaped design. In both designs, a series of circularly arranged holes enables flexible orientation of the connected elements. The connectors are fabricated melting layers of rough-milled HDPE, sourced from waste materials, which are cast in a mold incorporating an agave braid as a reinforcement. The manufacturing process is intentionally low-tech and accessible, relying only on basic tools and equipment for milling, melting, and casting. This approach makes the proposed connectors particularly suitable for adoption in developing countries. To assess their performance, physical and mechanical tests were conducted on the base material, evaluating density, void content, and tensile strength. The tensile strength of the finished connectors results in an average value of 12.73 MPa, with a standard deviation of 2.34 MPa and a coefficient of variation CV of 18.4%, consistent with the results of tests reported in the literature. Although the sample size is limited, the obtained data are sufficient to assess the feasibility of the proposed solution, demonstrating a reasonable reliability of both the molding process and the mechanical performance of the connector. Full article

Crimped electrical connections must maintain electrical continuity and mechanical load transfer capability under combined environmental and operational stressors throughout their service life. Although the environmental durability of electrical connectors has been extensively studied, previous studies have mainly focused on material, environmental, or electrical effects in isolation, whereas the coupled influence of crimp geometry on electrical–mechanical degradation and contact evolution remains insufficiently understood. In this study, crimp geometry was isolated as the primary independent variable to investigate geometry-driven degradation behavior in crimped connections. Three crimp configurations (Type A, Type B, and Type C) were subjected to temperature cycling (−55 °C to +70 °C), high humidity (90–95% RH), and combined chemical–electrical loading conditions involving representative fluids and short-circuit current. Electrical and mechanical responses were evaluated using relative resistance variation ΔR (%) and tensile strength change ΔT (%), while factorial ANOVA quantified parameter contributions. The results indicate that crimp geometry dominates the response under thermal–humidity exposure, whereas the chemical exposure type becomes the governing factor for electrical degradation under coupled chemical–electrical conditions. SEM analysis reveals that geometry-dependent plastic deformation governs contact continuity and void formation, leading to a transition from continuous conductive networks to fragmented contact structures. These findings are further supported by FEM analyses, which provide qualitative insight into the deformation response as a function of the geometric parameters. This work presents a geometry-based experimental framework for understanding the degradation behavior of crimped bonding structures under dual-exposure test conditions. Full article

Cross-laminated timber (CLT), an engineered timber product with distinctive features, has significantly broadened the applicability of timber structures. The self-tapping screws (STSs) with excellent anchorage performance have become one of the primary connectors used in CLT structures. However, the long-term withdrawal resistance is susceptible to environmental factors such as temperature and humidity fluctuations, which may lead to reduced CLT density and corrosion-induced degradation of the steel components. These effects represent a critical life-cycle challenge to the structural integrity and safety of timber connections. This study aims to investigate the withdrawal resistance of STSs in CLT under material aging effects. To achieve this, a two-step experimental program was designed. First, the effects of two artificial accelerated aging methods (ASTM D1037 and improved version of ASTM D1037) on the withdrawal resistance of STSs in glued laminated timber (glulam) were compared to validate the feasibility of the improved protocol. This comparison was necessary to ensure that the improved protocol produces a degradation pattern without altering the failure mechanism. Subsequently, a series of CLT specimens with embedded STSs were subjected to 0, 3 and 6 aging cycles to investigate the withdrawal behavior including aging characterization, failure modes, load–displacement curves, withdrawal capacity, and stiffness. The results indicate that the failure mode of CLT joint with STSs under the improved aging scheme was the consistent pull-out of STSs, identical to that observed in the glulam, confirming mechanistic consistency. After three and six aging cycles, the normalized withdrawal capacity retention rates were 104.98% and 95.36%, respectively. The stiffness is more significantly affected by aging. The corresponding normalized stiffness retention rates were 85.60% and 80.94%, respectively. As the number of aging cycles increased, the occurrence of wood fiber tearing became more pronounced and the ratio of the corresponding load to the peak load decreased. Furthermore, ensuring adequate distance from the vertical glue layer was found to lead to greater long-term resilience and withdrawal capacity. Full article

This paper presents a field case study of a mechanical failure that occurred in the bottom-hole assembly (BHA) during composite plug milling after hydraulic fracturing operations. The failure sequence was reconstructed using field hook load and torque records, operational documentation, and inspection of the damaged components recovered from the borehole. The results indicate that the critical condition developed progressively and was associated with increasing resistance to drill string movement, insufficient hole cleaning, and repeated attempts to continue milling and release the partially immobilized assembly. The observed damage pattern, together with the presence of residual cuttings and metallic debris in the borehole, supports the conclusion that the loss of the BHA section at the hydraulic safety sub resulted from the interaction of several adverse operational factors acting simultaneously, particularly the combined action of pull-up force and rotation under deteriorating borehole conditions. A supporting strength assessment of the hydraulic safety sub was used to relate characteristic operating points to the admissible working range of the connector. The study shows that hook load and torque data provide the greatest practical value when interpreted jointly and in their operational context rather than as isolated peak values. The findings support safer planning and execution of plug-milling and stuck-pipe remediation operations in highly deviated wells. Full article

Satellite communication greatly extends the reach and functionality of terrestrial communication networks, providing indispensable applications in defense, security, transportation, science, and technology. However, communication satellites operating in low Earth orbits face harsh space environments that severely affect their service life and reliability. The radio frequency (RF) module constitutes the core architecture of satellites, and its reliability directly determines overall satellite performance. While existing research has predominantly focused on the failure mechanisms of power amplifiers, investigations into the failure behaviors of other RF components—such as filters, frequency converters, and connectors—remain comparatively fragmented. Moreover, a comprehensive and systematic review addressing the RF module from a holistic, cross-component perspective is notably absent in the current literature. Therefore, this study comprehensively reviews existing studies on the reliability of spaceborne electronic components, highlighting both commonalities and differences in their failure mechanisms. Particular attention is given to in-orbit failure mechanisms of critical components, including power amplifiers, frequency converters, filters, and RF connectors. From the perspective of electronic components, this study assesses the in-orbit service capability, reliability, and lifespan of communication satellites. Finally, it identifies key challenges in ensuring the reliability of satellite electronic components and proposes future research directions and technical strategies for improvement. This study provides systematic insights for researchers in satellite communication RF modules and establishes a foundation for further advancements in the field. Full article

The genus Dendrobium, a well-known traditional Chinese medicinal herb, contains complex and diverse chemical constituents. The plant has been widely used in traditional medicine and has attracted increasing attention in modern pharmacological research due to its therapeutic potential. Bibliographic searches were conducted across various recognized databases. The exploration covered the years 1965–2025, and the connectors ‘and’ and ‘or’ were used with keywords such as “Dendrobium”, “phytochemistry”, “pharmacology”, “Cardiovascular diseases”, and “extracts”. The chemical composition of the genus Dendrobium mainly includes alkaloids, bibenzyls, flavonoids, phenanthrenes, phenylpropanoids, and terpenoids. Modern pharmacological studies have demonstrated that the genus Dendrobium exhibits multiple biological effects, including anti-tumor, antibacterial, anti-inflammatory, hypoglycemic, and neuroprotective activities. Notably, the genus Dendrobium shows significant potential in cardiovascular disease prevention and treatment through mechanisms such as antioxidant stress, anti-inflammation, regulation of lipid metabolism, anti-atherosclerosis, and inhibition of myocardial fibrosis. This review provides a comprehensive overview of the chemical components and pharmacological activities of Dendrobium plants, with emphasis on their cardiovascular protective effects. These findings offer a scientific basis for the further development and clinical application of Dendrobium medicinal resources. Full article

Background and objectives: Intolerance of uncertainty (IU) is a well-established transdiagnostic process in anxiety (ANX) and major depressive disorder (MDD), and has been increasingly implicated in anorexia nervosa (AN). However, most previous research including patients with AN has relied on total or subscale scores from eating disorder measures, which obscures how specific eating attitudes and body dissatisfaction symptoms relate to distinct facets of IU. The primary objective of the present study was to characterize item-level networks linking eating attitudes, body dissatisfaction, and IU in a pooled clinical mental health sample, alongside a control group (CG). Methods: Data were drawn from a sample including individuals with symptoms related to AN (N = 105), MDD (N = 97), and ANX (N = 240), a comorbid group (N = 84) with symptoms of two or more of these conditions, and a CG (N = 842). Separate item-level networks were estimated for clinical and control groups, and network structure and centrality indices were compared. Results: Network analyses revealed distinct organizational patterns between the clinical and control subsamples. Although both networks showed identical diameters, the clinical network exhibited a shorter average path length and higher clustering, indicating stronger local connectivity, whereas the control network showed higher modularity. In the clinical subsample, nodes related to binge eating, post-eating guilt, and IU emerged as the most central and acted as key connectors between clusters. In contrast, the control network displayed a more distributed centrality pattern, suggesting a more integrated and homogeneous network organization. Conclusions: This study provides new evidence to refine our understanding of how IU relates to eating attitudes and body dissatisfaction across diagnostic mental health boundaries. Identifying highly influential psychopathological symptoms across eating, mood, and anxiety disorders, as well as bridge nodes linking these mental health domains, is important for understanding transdiagnostic symptom dynamics. These insights may inform the development of more sensitive screening and diagnostic tools, as well as targeted intervention points to support more personalized and mechanism-focused treatments. Full article

Network dismantling—the targeted removal of nodes to degrade large-scale connectivity—plays a central role in resilience analysis, epidemic containment, and systemic-risk mitigation. Recent work shows that dismantling performance depends strongly on mesoscale modular structure, suggesting that community-aware strategies may offer advantages over classical centrality-based heuristics. In this work, we perform a large-scale, systematic evaluation of dismantling strategies and introduce gateways as a new mesoscale dismantling concept. While similar experiments exist using degree- and betweenness-based dismantling strategies, we check a new strategy based on gateways, which capture asymmetric entry points into communities and generalize the notion of inter-community connectors. Furthermore, we process a massive dataset of 568,584 LFR benchmark graphs, covering a wide range of degree distributions, community sizes, and mixing parameters. For evaluation, we use both extrinsic (ARI, NMI, FMI, VI) and intrinsic (Modularity, Coverage, Performance, Average Conductance, Average Internal Density) metrics. We find that across parameter regimes and evaluation metrics, classical strategies (degree, betweenness, community connections) and gateway-based dismantling exhibit broadly similar performance. Our results also corroborate recent findings that dismantling effectiveness is robust to the specific partitioning algorithm and that inter-community connectivity plays a dominant role in global fragmentation. The evaluation provides large-scale evidence that gateway-aware dismantling captures an operationally relevant mesoscale mechanism as good as previous approaches and motivates further empirical studies on real networks and cost-aware settings. Full article

Cu/Ni/Ag composite materials are widely used in the manufacturing of electrical connector contacts due to their excellent electrical conductivity and good wear resistance. During hot plugging and unplugging operations, electrical connectors inevitably generate arc discharge, leading to melting, splashing, and erosion of the contact material, which severely threaten system reliability and service life. To investigate the arc behavior of Cu/Ni/Ag composite electrical connectors during plugging and unplugging, this paper establishes a multiphysics coupling model incorporating electric field, fluid heat transfer, and laminar flow based on the COMSOL simulation software (version 6.2). The model employs a multiphysics coupling approach, incorporating electric field, fluid heat transfer, and laminar flow, to systematically simulate the formation and evolution mechanisms of the arc during plugging and unplugging. The study focuses on analyzing the effects of plugging and unplugging speed, operating voltage, and arc gap distance on the arc, exploring the temporal and spatial evolution characteristics and distribution patterns of arc temperature. The simulation results reveal that the arc temperature follows a radially decreasing gradient, with the core region exceeding 10,000 K. When the operating voltage increases to 1000 V, the arc peak temperature rises to 1.3 × 10⁴ K. As the arc gap distance increases, the arc coverage area expands, and the peak arc temperature increases by approximately 2% to 8%. As the plugging/unplugging speed is increased to 500 mm/s, the peak temperature of the arc increases from 1.19 × 10⁴ K to 1.3 × 10⁴ K. The distribution characteristics of the magnetic field are clearly correlated with the arc temperature field and the electric field intensity distribution and the current density also exhibits typical constriction characteristics. Prolonged arc duration is correlated with an upward trend in peak temperature. Further analysis indicates that the temperature distribution characteristics of the arc are constrained by the competition mechanism of energy deposition and diffusion, while the evolution characteristics of the arc are regulated by the coupling effect of electromagnetic field and mechanical work. The research results provide a theoretical basis and simulation methods for the design of arc-resistant structures in Cu/Ni/Ag composite electrical connectors. Full article