Search Results (185)

Background/Objectives: Fibromyalgia (FM) is a nociplastic pain syndrome characterized by chronic widespread pain, fatigue, sleep disturbance, cognitive dysfunction, and heightened sensitivity to somatic and environmental stimuli. Depressive symptoms and major depressive disorder (MDD) frequently co-occur with FM and are associated with greater disability, pain catastrophizing, sleep disruption, and poorer treatment response. Although pharmacological treatments can reduce symptoms in some patients, many individuals experience persistent functional and affective burden, highlighting the need for mechanism-based adjunctive strategies. Mindfulness-based interventions (MBIs), particularly mindfulness-based stress reduction (MBSR), have shown promise for improving functional impact, pain catastrophizing, perceived stress, depressive symptoms, sleep-related burden, and quality of life in FM. However, the effects of MBIs on pain intensity and biomarkers are less consistent. Methods: This narrative mechanistic review develops a hypothesis-generating multisystem neurobehavioral framework to explain how MBIs may influence pain–mood coupling in FM with depressive symptom burden. We define pain–mood recalibration as a reduction in the extent to which pain intensity, bodily vigilance, and interoceptive threat appraisal automatically drive depressive symptoms, rumination, avoidance, and functional disengagement. Results: Fibromyalgia-specific evidence most strongly supports cognitive–emotional mechanisms, including reduced catastrophizing, psychological inflexibility, rumination, perceived stress, and avoidance. Interoceptive, neural-network, autonomic, immune-inflammatory, and sleep-fatigue-behavioral pathways remain exploratory and require prospective mediation and moderation testing. Conclusions: Future trials should prioritize active controls, ecological momentary assessment, longitudinal biomarkers, neuroimaging, interoceptive tasks, and formal mediation/moderation models to determine which patients benefit, through which mechanisms, and under what biological and psychological conditions. Full article

Externally bonded fiber-reinforced polymer systems are used to strengthen steel structures, but their long-term reliability depends on the integrity of the FRP–adhesive–steel interfaces. Existing studies have examined static bond behavior, fatigue performance, and environmental durability as separate topics, while an integrated interface-centered synthesis remains limited. This paper reviews the bond behavior, fatigue degradation, and environmental durability of externally bonded FRP-to-steel systems. It compares specimen configurations, test and measurement methods, failure modes, governing factors, bond–slip relationships, fatigue degradation characteristics, environmental degradation mechanisms, residual bond capacity, and predictive models. The evidence indicates that static interfacial performance is governed by material properties, bond geometry, steel surface condition, corrosion, and bond defects. Repeated loading leads to stiffness degradation, slip accumulation, strength loss, and debonding, whereas the effects of variable-amplitude loading and the transferability of existing fatigue models remain insufficiently understood. Environmental exposure alters adhesive properties, interfacial adhesion, steel surface condition, and failure mechanisms, while existing durability models are calibrated for specific material systems and exposure regimes. Overall, a unified framework linking static bond behavior with fatigue- and environment-induced degradation remains to be established. The findings provide a basis for the characterization, modeling, and performance assessment of externally bonded FRP-to-steel systems. Full article

Electric-shovel top sheave bearings with sensor-embedded slots operate under harsh service loads, making them prone to fatigue crack initiation and propagation. Accurate predictions of crack growth within the bearing body are therefore essential for intelligent bearing design and reliability assessments because the bearing integrity directly affects shovel service life and safety. This paper presents a sub-modeling-based method that embeds initial cracks while preserving actual roller-ring boundary conditions and ensuring computational efficiency via adaptive mesh refinement. A global model first identifies critical crack-prone zones, after which the sub-model systematically examines the effects of the initial crack angle and sensor-embedded slot depth on the propagation behavior. The results indicate that both factors significantly increased the stress intensity factor (SIF). Among the evaluated designs, the 15 mm -deep slot produced the highest SIFs and the shortest predicted crack-propagation life, indicating that slot depth was a key design parameter under the investigated conditions. The findings provide theoretical support for the structural design and fatigue evaluation of intelligent electric-shovel top sheave bearings. Full article

Static wake steering can increase wind-farm power production, but its application to floating offshore wind farms requires assessment of the coupled wake, platform, structural, and station-keeping response. This study evaluates whether power-maximizing static yaw setpoints identified using the steady, control-oriented FLORIS model retain their benefit when transferred without re-optimization to a coupled FAST.Farm floating wind-farm model. The reference farm comprises four IEA Wind 15 MW turbines mounted on VolturnUS-S semi-submersible platforms. Greedy and static wake-steering operations are compared at three below-rated wind speeds, three sea states, and five matched turbulent-inflow realizations, resulting in 90 farm-level FAST.Farm simulations. Wake behavior is characterized through wake-center deflection, meandering, and velocity-deficit profiles, while turbine and mooring fatigue responses are evaluated using paired damage-equivalent-load statistics. Static wake steering increases mean farm power under all nine investigated wind–wave conditions. The gains are approximately 5.1–$5.2\%$ at $7\mathrm{m}{\mathrm{s}}^{-1}$, $5.0$–$5.1\%$ at $8\mathrm{m}{\mathrm{s}}^{-1}$, and $4.0$–$4.2\%$ at $9\mathrm{m}{\mathrm{s}}^{-1}$, with all paired $95\%$ confidence intervals remaining above zero. The gain results from a power redistribution in which the intentionally yawed upstream turbine incurs a local loss that is exceeded by the combined recovery of the downstream turbines. The fatigue response is strongly component- and turbine-dependent. The paired farm-mean blade-root DEL decreases by $0.82$–$2.24\%$, whereas the tower-base DEL increases by $0.76$–$2.78\%$, and the FairTen1 response generally increases by $0.88$–$2.92\%$. The farm-mean yaw-bearing response is mixed, ranging from a $1.15\%$ reduction to a $4.32\%$ increase. Turbine-level analysis reveals larger localized penalties, reaching approximately $10.4\%$ for the yaw-bearing DEL and $12.8\%$ for FairTen1. Spectral analysis associates the yaw-bearing response with yaw-induced aerodynamic and structural excitation, while the tower-base response is strongly influenced by low-frequency wave–platform dynamics. A complementary FLORIS sensitivity analysis demonstrates that the optimized aerodynamic benefit depends strongly on wind direction, spacing, wind speed, and turbulence intensity. For a Tampen-derived 11-turbine layout, resource weighting over the modeled 4–$13\mathrm{m}{\mathrm{s}}^{-1}$ interval produces an annual energy-contribution increase of $3.653\mathrm{GWh}{\mathrm{year}}^{-1}$, or $0.921\%$. These results provide numerical evidence that static wake steering can retain a positive power benefit in a coupled floating wind-farm environment, but controller assessment must include turbine- and component-specific dynamic loads rather than farm power alone. Full article

Due to their high strength-to-weight ratio and corrosion resistance, carbon fiber-reinforced polymers (CFRPs) are increasingly used as tension elements in bridge engineering. Their pronounced anisotropy, resulting from stiff carbon fibers and a weaker polymer matrix, is critical for fatigue behavior under multiaxial dynamic stress states, such as those occurring in stay cables over saddles of extradosed bridges or at clamps of suspension-bridge hangers. This multiaxial loading can cause progressive damage accumulation in the contact regions and lead to premature failure. To study this efficiently, an energy-based progressive damage analysis (PDA) model for CFRP tension elements under multiaxial fatigue loading was implemented as a vectorized user material in ABAQUS^® 6.14 (VUMAT in FORTRAN) and validated against tension-tension fatigue tests on pin-loaded CFRP straps. The model was then applied to two representative bridge applications, viz. a clamped CFRP rod and a CFRP cable bent over a saddle, where parameters such as clamping pressure, maximum stress level, and friction coefficient were varied to quantify their influence on fatigue life and to assess suitability in line with fib recommendations. The results indicate that clamping pressures inducing transverse compressive stresses above roughly 85% of the CFRP’s transversal compressive strength significantly reduce fatigue life, whereas keeping the maximum fatigue stress below about 40% of the mean longitudinal tensile strength, the stress amplitude below 200 MPa, and the friction coefficient near 0.2 yields fatigue lives exceeding 2 × 10⁶ load cycles, which is satisfactory under fib criteria. Full article

Distortion-induced fatigue is an important failure mechanism in steel plate girder bridges. Existing studies have advanced the understanding of local stress responses and damage identification of distortion-sensitive details; however, the mechanism by which traffic lane distribution affects distortion-induced fatigue characteristics and governs fatigue damage accumulation remains insufficiently understood. To address this issue, a global–local finite element model was established using ABAQUS 2016 to investigate deformation transfer behavior and fatigue stress responses in a steel plate girder bridge. Longitudinal and transverse load position analyses were conducted to quantify the spatial characteristics of fatigue responses. Furthermore, a lane-distribution-based fatigue damage assessment framework was developed and verified. The results demonstrated that distortion-induced fatigue response is governed by deformation incompatibility, with web gap welds identified as the critical fatigue details under different structural configurations. The transverse displacement at the stiffener end showed a strong correlation with fatigue stress (Spearman coefficients > 0.8). The transverse influence range extended across almost the entire region between the two main girders, indicating that adjacent-lane loads contribute to fatigue damage accumulation. Compared with the single-lane critical load method, the proposed framework better represents fatigue damage evolution under actual lane distributions and captures asymmetric damage between the two girders, with the maximum difference reaching 46.7%. This study provides new insights into distortion-induced fatigue evolution from the perspective of traffic lane characteristics and offers a refined approach for fatigue assessment of existing steel plate girder bridges. Full article

To address the challenge of fatigue life prediction caused by multiple-crack interactions in ship and offshore structures, this study proposes a dynamic Bayesian network (DBN)-based method for predicting the fatigue life of structures with multiple cracks, which is systematically validated through physical experiments. First, a numerical model of a representative structure containing a central hole and multiple initial cracks was established based on the coupled simulation platform of ABAQUS and Franc3D. The nonlinear interaction behavior among multiple cracks under different geometric configurations was systematically investigated. Subsequently, a neural network surrogate model was developed, in which geometric features and crack lengths were employed as inputs and key fracture mechanics parameters were taken as outputs, enabling efficient prediction of complex stress intensity factor (SIF) fields. On this basis, fatigue crack growth experiments were conducted on DH36 high-strength steel specimens containing multiple cracks, and crack evolution data under realistic cyclic loading conditions were obtained. Finally, by coupling the surrogate model with the Paris law as the state transition equation and incorporating sparse experimental observations as dynamic updating information, a dynamic Bayesian network framework based on the particle filtering algorithm was established. This framework enables posterior probability tracking of multiple-crack fatigue states and rolling prediction of the remaining fatigue life. The results demonstrate that the proposed method can effectively mitigate the error accumulation associated with deterministic simulation models during long-term open-loop prediction while relying only on a limited number of discrete observation anchors. Consequently, the prediction accuracy of the fatigue life of multiple-crack systems is significantly improved. Furthermore, under crack co-propagation conditions, the proposed framework exhibits a strong capability to capture the propagation retardation of secondary cracks induced by shielding effects. The proposed method provides a theoretical foundation and technical support for the dynamic assessment of fatigue damage and the development of digital twins for complex structures containing multiple cracks. Full article

Hydrogen energy systems—proton exchange membrane fuel cells (PEMFCs), water electrolyzers, and high-pressure hydrogen storage vessels—are increasingly deployed in transportation, maritime, aerospace, and stationary applications where mechanical vibration is unavoidable. Yet vibration research remains fragmented into single-technology studies whose findings often appear inconclusive or contradictory. This review provides a cross-technology assessment of vibration phenomena in hydrogen energy systems, covering PEMFC performance and degradation, structural dynamics of stacks and storage vessels, water management and two-phase flow, diagnostics and modeling, and application-specific challenges for road, marine, aircraft, and space systems. By organizing the evidence around a small set of shared mechanisms—loss of mechanical preload (bolt loosening), two-phase flow disruption, and fatigue-driven crack growth—we establish a unified framework that reconciles the seemingly case-dependent results of earlier, single-technology reviews. Whether vibration acts as friend or foe is governed by a consistent parameter set: amplitude, frequency, direction, and cumulative exposure time. Short, low-frequency excitation can aid water removal in fuel cells, improve cold-start behavior, and raise electrolyzer hydrogen yield by up to 128%, whereas sustained exposure roughly doubles PEMFC voltage degradation rates, loosens clamping bolts, and drives fatigue in storage-vessel supports. The evidence base is currently dominated by PEMFC studies, and this review accordingly treats fuel cells in the greatest depth. Priority research needs are identified: standardized vibration test protocols, long-duration durability data, vibration characterization of electrolyzers prior to offshore deployment, and coupled multiphysics models supporting vibration-aware design. Full article

Ultra-supercritical (USC) steam turbines combine severe steam conditions with increasingly frequent start-up, shutdown, and load-following operations. Their main steam valves must preserve pressure boundary integrity, sealing, and rapid actuation while non-uniform heating, creep, cyclic plasticity, oxidation, wear, and contact redistribution alter component geometry. However, the relevant evidence remains fragmented across alloy development, component thermo-mechanics, valve aerodynamics, and lifetime monitoring. This short, mechanism-oriented review integrates these domains through a material structure–function framework in which deformation relative to assembly clearance governs jamming risk. It synthesizes evidence on heat-resistant body and surface materials, 9–12% Cr steel stability, weldability and repair sensitivity, and cold, warm, and hot start-up histories. It also evaluates creep–fatigue interaction, contact, flow-induced vibration, multi-physics modeling, validation, uncertainty, monitoring, and digital twins. The synthesis shows that neither peak equivalent stress nor steady-state temperature alone can establish functional reliability. Credible assessment requires temperature-dependent material data, realistic steam-side heat transfer, cyclic constitutive behavior, initial and residual clearances, manufacturing and assembly tolerances, state-dependent friction, uncertainty analysis, and corroborating plant or inspection evidence. The most consequential research needs are valve-level validation datasets, thermal contact testing, function-oriented life criteria, and uncertainty-aware digital twins that jointly inform materials, geometry, and transient operation. Full article

Background/Objectives: Breast cancer treatments, including adjuvant radiotherapy, significantly improve survival but are associated with cancer-related fatigue (CRF), a debilitating symptom that severely impacts quality of life. Previous studies often evaluate fatigue by combining radiotherapy with systemic therapies, confounding its independent association. This study aims to isolate the specific relation between exclusive radiotherapy and the longitudinal progression of fatigue in surgically treated breast cancer patients. Methods: A longitudinal study was conducted in a cohort of 70 women with breast cancer who underwent breast-conserving surgery and subsequent adjuvant radiotherapy. Cancer-related fatigue levels were evaluated across behavioral, affective, sensory, and cognitive dimensions using the Piper Fatigue Scale-Revised (PFS-R), while global health status and quality of life (QoL) were measured using the EORTC QLQ-C30 questionnaire, both before and after radiotherapy. Data were analyzed using generalized linear mixed-effects models. Results: Following radiotherapy, a marked and statistically significant increase was observed in total fatigue (1.61 ± 1.16 vs. 5.37 ± 2.76; p < 0.001) and across all specific domains (p < 0.001), accompanied by a decline in global health status (82.6 ± 20.2 to 60.1 ± 29.2). Assessment time (pre- vs. post-RT) was identified as the factor most strongly associated with an increase in fatigue. However, better baseline global health status significantly attenuated the increase in total, behavioral, affective, and sensory fatigue (time × QoL interaction, p < 0.001). Furthermore, higher physical activity levels were significantly associated with lower behavioral fatigue (p = 0.042) and showed a protective trend for sensory (p = 0.055) and total fatigue (p = 0.092). Conclusions: Radiotherapy is strongly associated with a significant increase in cancer-related fatigue scores across all dimensions. Better baseline quality of life acts as a protective factor that is associated with attenuated fatigue progression, while regular physical activity correlates with a mitigated impact, particularly within the behavioral domain, although it did not reach statistical significance across all fatigue dimensions. These findings highlight the critical need for routine clinical monitoring of fatigue and strongly support the implementation of structured, exercise-based interventions during adjuvant treatment. Full article

We conducted an exploratory evaluation of short-term changes following participation in a two-day intensive training programme aimed at addressing sustainability-oriented and project-management-related psychological outcomes, focusing on self-efficacy and behavioral intentions among university staff and researchers. A repeated-measures pre-post design was adopted. A total of 28 participants took part in the training, which covered the fundamentals of project management (including its main phases and processes) and the integration of sustainability principles into project management practices. Participants were assessed at two time points: prior to the training (T1) and immediately after its completion (T2). Primary outcomes included project sustainability self-efficacy, project management self-efficacy, pro-sustainability behavioral intentions, and behavioral intentions to adopt new project management practices. Cognitive fatigue and perceived training utility were assessed at T2 to capture participants’ immediate post-training experiences. Changes over time were examined using paired-samples t-tests and regression models controlling for baseline (T1) levels of each outcome variable. Participants showed significant increases from T1 to T2 across all outcome variables, with a moderate effect for project sustainability self-efficacy (Cohen’s d = 0.42) and large to very large effects for project management self-efficacy (d = 1.35), pro-sustainability behavioral intentions (d = 2.08), and behavioral intentions to adopt new project management practices (d = 1.38). Baseline levels generally predicted post-training scores, suggesting partial temporal stability, whereas perceived training utility showed weak and non-significant associations with post-training outcomes. Cognitive fatigue did not emerge as a significant predictor of any outcome. Overall, these exploratory findings provide preliminary evidence of short-term changes observed following participation in the training programme in sustainability- and project-management-related psychological outcomes. However, given the small convenience sample, single-group pre-post design, and immediate post-training assessment, the findings should be interpreted cautiously and do not allow causal conclusions regarding the effects of the training programme. Larger controlled and longitudinal studies are needed to determine whether these changes can be replicated and sustained over time. Full article

E-cargo bikes have emerged as a promising solution for sustainable urban mobility and last-mile logistics. However, their structural design must ensure durability and safety under demanding cargo transport and daily operating conditions. This study evaluates the structural performance of three single-track E-cargo bike frame typologies, Urban, Long John and Long Tail, using finite element analysis under fatigue and impact loading conditions derived from EN 15194:2020 and EN 17860-2:2024. Numerical models of aluminum 6061-T6 frames were developed to simulate cyclic pedaling, horizontal, seat-post and vertical cargo loading forces, together with falling-frame and falling-mass impact tests. Structural performance was assessed through fatigue life, stress distribution, damage initiation, plastic strain and permanent wheelbase deformation. The Urban and Long John frames satisfied the adopted fatigue-life requirements, whereas the Long Tail frame failed the vertical loading-area fatigue test with a predicted fatigue life of 5.22 × 10⁴ cycles, below the required 2 × 10⁵ cycles. The maximum von Mises stresses during the falling-frame impact test reached 384 MPa, 326 MPa and 356 MPa for the Urban, Long John and Long Tail frames, respectively, while the corresponding permanent wheelbase deformations remained limited to 2.07 mm, 1.97 mm, and 1.43 mm, all below the acceptance criterion. These results highlight the influence of frame geometry and cargo location on structural behavior and support future frame optimization. Full article

The roller–raceway contact response is a key factor affecting stress concentration, fatigue initiation, and raceway spalling in spherical roller thrust bearings. Uncertainty analysis of this response is therefore important for revealing how practical parameter fluctuations affect bearing contact behavior and for supporting robust bearing design and operating-condition optimization. In this paper, a multibody dynamic model of a spherical roller thrust bearing is established by explicitly considering the main internal contact pairs, including roller–raceway, roller–flange, roller–cage, and cage–guide interactions. The model is used to obtain the transient roller–raceway contact loads under coupled axial loading and rotational motion. The resulting contact loads are introduced into a finite element contact model to evaluate the dynamic contact stress response of the inner raceway. To assess the effects of random uncertainties on this response, an improved deep neural network (DNN) surrogate model is developed. An attention mechanism deep neural network (AM-DNN) is improved by incorporating feature importance information from random forest (RF) into its attention mechanism, and the resulting model is denoted by RF-AM-DNN. Validation on the generated dataset demonstrates that the proposed RF-AM-DNN outperforms conventional surrogate models in prediction accuracy. Finally, the RF-AM-DNN is used to investigate the uncertainty characteristics of dynamic contact stress in spherical roller thrust bearings under multiple uncertainty factors. Full article

Objectives: To compare the geometric design, metallurgical properties, mechanical performance, and irrigation dynamics of Reciproc Minima (M20 and M25) and Reciproc Blue R25 instruments. Methods: One hundred and eighty instruments (n = 60/group) were evaluated. Geometry was analyzed using stereomicroscopy, scanning electron microscopy, and 3D surface scanning. Metallurgical characteristics were assessed by energy-dispersive X-ray spectroscopy and differential scanning calorimetry. Mechanical performance tests (n = 10/group) included cyclic fatigue, torsional resistance, bending resistance, buckling resistance, and cutting efficiency. Irrigation dynamics were examined through computational fluid dynamics simulations based on a micro-CT-derived mandibular molar model prepared according to each system and combined with open-ended, side-vented, or double side-vented needles. Data were analyzed using one-way ANOVA or Kruskal–Wallis tests (α = 0.05). Results: The results showed that blade dimensions increased progressively from Minima M20 to Reciproc Blue R25. All instruments had S-shaped cross-sections and non-active tips. Energy-dispersive spectroscopy confirmed near-equiatomic NiTi composition, and similar phase transformation temperatures were observed across groups. Minima M20 showed the highest cyclic fatigue resistance (p < 0.0001), whereas Minima R25 exhibited greater angular deflection (p < 0.0001). Reciproc Blue R25 had the highest buckling resistance and lowest flexibility (p < 0.0001). M25 showed the lowest axial force, indicating the numerically highest cutting efficiency, but it did not differ significantly from Reciproc Blue R25 (p > 0.05). No needle delivered irrigant to working length. The open-ended needle achieved greater apical penetration, particularly with Reciproc Blue R25. Minima M20 generated the highest wall shear stress, and Reciproc Blue R25 the lowest apical pressure. Conclusions: Reciproc Minima and Reciproc Blue R25 showed similar metallurgical characteristics; however, differences in geometric design resulted in distinct mechanical behaviors and irrigation fluid dynamics. These findings suggest that low-taper reciprocating instruments may represent a conservative alternative in anatomically challenging canals, while clinicians should consider the associated differences in mechanical behavior and irrigation dynamics when selecting the most appropriate instrument. Full article

Cancer-related fatigue (CRF) remains difficult to manage, and the impact of metal ion-regulated cell death on peripheral fatigue during anticancer therapy is unclear. Here, we investigated whether ferroptosis inducers (FINs) potentiate copper ionophore (CIN)-triggered cuproptosis in skeletal muscle and aggravate lung cancer-related fatigue (LCaRF), and evaluated redox-based interventions. LCaRF cellular models were established using C2C12 exposed to LLC/M109 tumor-conditioned supernatants and treated with FINs (sorafenib/erastin) plus CIN + CuCl₂ (CIN–Cu + FINs). Cell viability, lipid peroxidation, DLAT aggregation (cuproptosis hallmark), copper/glutathione (GSH), mitochondrial function, and FKBP5/Nrf2–HO-1 signaling were assessed with pharmacologic and genetic modulation. An orthotopic lung cancer mouse model underwent wheel-running, tail suspension, and open-field testing with tetrathiomolybdate (TTM) or hydrogen as interventions. FINs sensitized C2C12 cells to CIN–Cu cytotoxicity and increased DLAT aggregation; copper chelation with TTM attenuated these effects. FINs depleted GSH and amplified mitochondrial dysfunction/ROS; exogenous GSH or hydrogen reduced DLAT aggregation and restored mitochondrial indices. FKBP5 was markedly upregulated by CIN–Cu + FINs and linked to suppressed antioxidant defense (Nrf2/HO-1). In vivo, CIN–Cu + FIN treatment exacerbated fatigue-like behaviors, while TTM or hydrogen partially improved performance. FIN–CIN combinations may aggravate skeletal muscle injury and fatigue-like phenotypes in LCaRF models by promoting cuproptosis via GSH depletion and FKBP5/Nrf2-HO-1 dysregulation. Full article