Search Results (4,478)

Multiple sclerosis (MS) is a chronic central nervous system disease with heterogeneous symptoms, including gait disturbances and motor fatigue, affecting daily functioning and quality of life. Episodic assessments may miss within-day functional fluctuations, whereas home-like monitoring may characterize them. This technical proof-of-concept case study quantified gait parameters (velocity, step length, and variability) during natural walking, explored temporal changes in gait and activity as potentially fatigue-relevant motor-performance patterns, and examined the feasibility of deriving candidate digital measures in MS. Three individuals with MS (one EDSS 1; two EDSS 3) were monitored in an instrumented apartment for 6.5–9.0 h using three LiDAR sensors. Gait parameters, region transitions, activity patterns, EDSS, FSMC, VAS-F, and available data-yield indicators were summarized descriptively. Compared with published healthy-adult references, P01 and P03 showed lower walking velocity, and P03 showed reduced step length. P01 maintained stable gait, P02 increased afternoon walking velocity, and P03 showed an afternoon velocity decline and a smaller step length decrease. The behavioral profiles described different spatial activity patterns, and the activity levels remained low during monitoring. LiDAR-based monitoring may provide a privacy-preserving approach to capture gait and activity variations as candidate variables for future validation without establishing fatigue specificity, clinical validity, or diagnostic thresholds. Full article

In order to enhance the contact fatigue performance of the Cr12Mo1V1 die steel component, the ultrasonic impact surface-modification process was introduced into the heat treatment process of 1060 °C quenching + cryogenic treatment (−150 °C × 2 h) + two times of tempering at 520 °C × 2 h in this paper. The influence of the ultrasonic impact number on the surface morphology, roughness, micro-hardness value, residual stress, microscopic morphology of spalling pits, contact fatigue life, and EBSD inverse pole figure of the Cr12Mo1V1 die steel component were investigated utilizing a laser confocal microscope, 3D laser confocal microscope, micro-hardness tester, X-ray stress meter, scanning electron microscope, rolling contact fatigue testing machine, and EDAX-TSL system equipped with a field-emission scanning electron microscope, respectively. In comparison to other ultrasonic impact numbers, the Cr12Mo1V1 die steel component owned the smallest roughness of 0.027 μm, the highest micro-hardness value of 867 Hv_0.1 and the largest residual compressive stress of −1318 MPa, respectively. Meanwhile, the contact fatigue life of the Cr12Mo1V1 die steel component was significantly improved by 223% to 5.231 × 10⁷ cycles. After ultrasonic impact treatment, the spalling pits revealed that the crack propagation angle increased from 28° to 34°, the depth increased from 153 μm to 175 μm, and the failure mode consisted of Hertz’s contact theory. This study provides an effective surface strengthening solution for enhancing the contact fatigue performance of Cr12Mo1V1 die steel components. Full article

Background/Objectives: Chemotherapy-related fatigue (CRF) affects 50–80% of children receiving chemotherapy and significantly impairs quality of life. Despite the family-centered care framework guiding pediatric oncology practice, evidence on parent-delivered, home-based non-pharmacological interventions for CRF remains limited. This study aimed to evaluate the effect of a parent-delivered warm-water foot bath on CRF in children aged 7–12 years undergoing chemotherapy. Methods: A two-arm parallel randomized controlled trial (NCT06529484; October 2024–May 2025) was conducted at a university hospital pediatric hematology–oncology outpatient clinic. Sixty-one children with stage 3–4 Non-Hodgkin Lymphoma (intervention, n = 29; control, n = 32) were randomized using computer-generated allocation and sequentially numbered, opaque, sealed envelopes. Following structured family education, parents delivered nightly foot baths (38–40 °C, 20 min) at home for 7 consecutive days after chemotherapy administration. Adherence and fidelity were monitored via a daily WhatsApp communication protocol. Fatigue was assessed daily using the Oncology Nursing Society Visual Fatigue Scale (ONS-VFS; primary outcome) and pre/post analysis using the Pediatric Oncology Fatigue Assessment Scale (child and parent forms). Reporting followed CONSORT 2025. Results: Median ONS-VFS scores declined significantly over the 7 days in both groups (Friedman p < 0.001 for each), from 5 (Day 1) to 2 (Day 7); between-group comparisons showed no statistically significant differences on any day (all p > 0.05). On the Pediatric Oncology Fatigue Assessment Scale, no between-group differences favored the intervention; a single child-report subscale difference favored the control group and is most plausibly attributable to multiple comparisons. Adherence was complete (100%), no adverse events occurred, and all 61 participants completed the protocol. Conclusions: A parent-delivered foot bath is a safe, feasible, and well-accepted family-centered nursing intervention, with complete adherence and no adverse events. This trial was not powered to detect between-group differences and did not demonstrate superiority over standard care; adequately powered trials are needed to determine efficacy. Full article

As a core load-bearing component for railway vehicles, rails are largely responsible for the safety and stability of train operation, and their service performance is inherently governed by material microstructure. In this study, rails with varied pearlite interlamellar spacing were prepared and laid on field tracks for 8 months of service testing to investigate the influence of pearlite interlamellar spacing on rail wear and rolling contact fatigue (RCF). The results indicate that decreasing pearlite interlamellar spacing facilitated tread work hardening and reduced cumulative wear loss of rails. At the early service stage, rails with coarse pearlite lamellae exhibited earlier RCF crack initiation and longer crack morphologies, while rails featuring finer pearlite lamellae exhibited the latest-occurring crack initiation. With prolonged service duration, wear loss rose continuously, and the tread hardening rate first increased sharply and then tended to gradually become stable. Obvious differences in damage evolution were observed for rails with different pearlite interlamellar spacing. Coarse-lamellar rail suffered sparse short cracks dominated by wear; fine-lamellar rail developed dense fast-growing cracks controlled by RCF; and medium-lamellar rail achieved a relatively good balance between wear and RCF. A competitive relationship exists between wear and RCF during rail service. Reasonable regulation of pearlite interlamellar spacing facilitates a balanced evolution of wear and RCF, which provides a feasible microstructural optimization strategy for improving the service performance and service life of pearlitic rails. Full article

Offshore floating photovoltaics (OFPVs) offer a promising route for expanding solar energy development from land and inland waters to marine space, particularly in China’s coastal regions where electricity demand, land-use constraints, offshore wind infrastructure, and photovoltaic manufacturing capacity are highly concentrated. This review examines the development status, structural concepts, hydrodynamic challenges, research methodologies, reliability issues, and future pathways of OFPV systems in China from the perspective of marine engineering. Demonstration projects, representative platform concepts, and recent studies on environmental loading, platform motion, multi-body interaction, connector and mooring responses, and hydroelastic behavior are systematically synthesized. The review shows that Chinese OFPV technology has progressed from conceptual exploration to prototype testing and sea-based validation, with flexible membrane, steel-frame, semi-submersible, tensioned floating-island, HDPE modular, and composite-material concepts under active investigation. However, mature and replicable engineering solutions remain limited. Key barriers include survivability under extreme sea states, fatigue reliability of large arrays, corrosion, biofouling, material degradation, insufficient long-term field data, and the lack of dedicated design standards. Future development should emphasize array-level hydrodynamic design, coupled connector–mooring optimization, life-cycle reliability assessment, full-scale monitoring, and integration with offshore wind, wave energy, floating breakwaters, aquaculture, and other marine energy systems. Full article

This study investigates the mechanical performance and fatigue behavior of a woven glass fiber-reinforced epoxy laminated composite classified as IEC 60893 EPGC 203, widely used in structural insulating components for high-voltage (HV) equipment. With evolving energy infrastructures introducing dynamic and cyclic loading conditions, understanding the long-term mechanical reliability of such materials has become increasingly important. A comprehensive experimental program was conducted, including flexural, compressive, tensile, Charpy impact, and fatigue tests. Mechanical properties were evaluated according to relevant ISO standards at room temperature and 120 °C to assess temperature-dependent performance. Fatigue tests were performed under fully reversed loading conditions ($R=-1$), and stress–life (S-N) curves were established. The results revealed notable reductions in strength and stiffness at elevated temperature, together with progressive damage accumulation under cyclic loading. Failure features observed after fatigue testing were correlated with static mechanical properties to improve understanding of degradation behavior. The study is limited to the mechanical and fatigue characterization of EPGC 203 and does not include dielectric evaluation. Therefore, its relevance to HV applications is considered from the standpoint of the mechanical reliability of structural insulating components. The findings provide essential insights into the durability and reliability of EPGC 203 composites under realistic service conditions. Full article

To reduce carbon emissions from cement-treated aggregate base layers and examine the nonlinear service behavior of semi-rigid materials, supersulfated cement (SSC) was used to replace ordinary Portland cement (OPC). A dynamic triaxial loading protocol was adopted to separate the effects of bulk stress and shear stress on the dynamic resilient modulus of supersulfated cement-treated aggregate (SSC-CTA). A fatigue damage equation was developed based on the strain energy balance during cracking, and Paris’ law damage parameters were introduced to compare the damage growth rates of SSC-CTA and ordinary Portland cement-treated aggregate (OPC-CTA). Finite element analysis and partial differential equations were further used to link the stress-dependent resilient modulus with structural fatigue life. The results show that SSC-CTA had a lower dynamic resilient modulus than OPC-CTA under the same stress state. The average resilient modulus of SSC-CTA was 978 MPa, which was 15.47% lower than that of OPC-CTA. For both materials, the modulus increased with bulk stress and decreased with octahedral shear stress, and the NCHRP 28A model accurately predicted this nonlinear behavior. Although SSC-CTA had a lower modulus, its indirect tensile strength reached 864.3 kPa, representing a 52.65% increase compared with OPC-CTA. The Paris’ law parameters further indicated that SSC reduced the damage growth rate during crack propagation. The finite element results showed that the predicted structural fatigue life of SSC-CTA increased by 4.49–35.90% under different load levels. Full article

Background and Objectives: Fibromyalgia (FM) is a chronic primary pain syndrome. Its hallmark symptom is widespread pain, often accompanied by fatigue, sleep disturbances, and cognitive symptoms. Online surveys efficiently collect patient-reported data, but individuals recruited through this approach remain poorly characterized. This study aimed to describe a large online cohort of individuals with FM, providing data for comparison with the Italian Fibromyalgia Registry (IFR). Materials and Methods: Participants who self-reported a physician diagnosis of FM completed an online survey assessing socio-demographic and clinical characteristics, treatments and their perceived effectiveness, lifestyle, and impact variables. Disease severity and symptom burden were assessed using the Fibromyalgia Impact Questionnaire—Revised (FIQR), Widespread Pain Index (WPI), and Symptom Severity Scale (SSS). Participants were classified according to the 2016 American College of Rheumatology (ACR) criteria. Descriptive statistics were computed, and exploratory analyses assessed sex differences and differences according to ACR status using independent-samples t-tests with Bonferroni correction. Results: A total of 6022 participants were included (mean age 52.3 ± 10.3 years, 96.7% female). Nearly half (49.6%) reported pain duration > 10 years, and 50.4% had received conflicting diagnoses. Disease burden was high, with >70% classified as moderate-to-severe according to the FIQR. Overall, 79.4% fulfilled the 2016 ACR criteria. Participants not fulfilling the criteria showed lower symptom severity, although considerable clinical overlap was observed between groups. Pharmacological treatments were used by 81.1% of participants and non-pharmacological approaches by 55.1%, both with moderate perceived effectiveness. FM substantially affected daily life, particularly work and social functioning. After correction for multiple comparisons, sex differences were limited to FIQR functioning and symptom domains, with small effect sizes. Conclusions: Compared with published registry-based data, participants recruited through this online survey reported a higher symptom burden and longer pain duration, while showing a broadly similar symptom profile. Although the descriptive nature of the comparison precludes causal inferences, the findings suggest that online surveys and clinical registries may provide complementary perspectives on the FM population. Full article

To address the permeability deterioration and fatigue degradation of modified soil under high-moisture service conditions, this study investigated the impermeability and fatigue behaviour of modified soil under different lime contents, compaction degrees, moisture contents and curing durations through laboratory permeability tests and cyclic loading tests. The results indicate that the permeability coefficient of modified soil decreases with increasing lime content, compaction degree and curing age, while it increases with increasing moisture content. Under 28-day curing conditions, increasing the lime content from 4% to 10% reduced the permeability coefficient by 80.4%. Under cyclic loading, the accumulated fatigue failure cycles of modified soil increased with higher lime content and longer curing periods, but decreased with increasing peak load under the adopted step-loading protocol; the accumulated fatigue failure cycles increased by up to 1.89 times. In addition, an empirical peak load–cycle relationship was obtained only for the tested modified soil with 8% lime content under a 120-day curing period and the adopted step-loading protocol in this study, providing experimental support for engineering design and service-life evaluation under similar loading conditions. Full article

To investigate the influence of porosity defects and the strengthening effect of bonded iron-based shape memory alloy (Fe-SMA) plates, fatigue tests were conducted on defect-free, porosity-containing, and Fe-SMA-strengthened U-rib butt-welded specimens. A numerical model considering porosity defects and the bonded Fe-SMA plate was also established and validated against the experimental results. The results show that porosity defects significantly increased the local stress level near the crack. Under a load of 60 kN, the stress at the section 2 mm from the crack edge increased from 98 MPa to 139.5 MPa. Meanwhile, the fatigue life decreased from 260 × 10⁴ cycles to 127 × 10⁴ cycles. After Fe-SMA strengthening, the stress decreased to 75.59 MPa, and the fatigue life increased to 326 × 10⁴ cycles, which was 2.57 times that of the unreinforced defective specimen. The Fe-SMA plate did not change the fatigue crack propagation path but effectively slowed crack growth through local stiffness enhancement and activation-induced pre-compressive stress. Parametric analysis further showed that, among the investigated numerical cases, an activation temperature of 200 °C produced the largest predicted strengthening effect. Increasing the pore diameter from 0.5 mm to 2.0 mm reduced the reinforcement effect from 69.45% to 52.98%, and increasing the crack length from 10 mm to 50 mm reduced it from 65.41% to 35.53%. These results indicate that bonded Fe-SMA plates can effectively improve the fatigue performance of U-rib butt-welded joints with porosity defects, especially when applied before excessive crack growth occurs. Full article

Pearlitic wheel steel subjected to thermal–mechanical fatigue (TMF) during braking can undergo catastrophic fracture. This study clarifies the microstructural evolution governing the macroscopic cyclic hardening/softening behavior of pearlitic wheel steel under thermal–mechanical fatigue (TMF) with a constant mechanical strain range of −0.4% to +0.2%. At lower temperature amplitudes (200–500 °C), the geometrically necessary dislocation (GND) density reaches 20.4 × 10¹⁴/m² during initial cycles, corresponding to cyclic hardening due to dislocation pile-ups at cementite lamellae interfaces. With increasing cycles, the GND density decreases to 12.3 × 10¹⁴/m², concurrent with softening arising from lamellar bending/fracture, partial spheroidization, and dynamic recrystallization of ferrite. At higher temperature amplitudes (200–730 °C), the GND density decreases from 8.8 × 10¹⁴/m² to 3.5 × 10¹⁴/m², reflecting sustained cyclic softening dominated by thermally activated mechanisms, including cementite spheroidization and dislocation annihilation. The resulting softened microstructure consists of ferrite grains, intragranular dispersed cementite, and chain-like coarse cementite at boundaries. Unlike previous studies that focused on single loading conditions (e.g., thermal fatigue, rolling contact fatigue, or wear), the present work addresses the more complex TMF scenario and quantitatively elucidates the interplay between mechanical response and microstructural evolution in pearlitic steel. This work provides theoretical guidance for the development of a fatigue life prediction model for pearlitic wheels under braking. Full article

This study evaluated fracture risk associated with varying trochlear groove depth-to-patellar thickness (D/T) ratios in toy and small-breed dogs using finite element analysis and cadaveric mechanical testing. Finite element models derived from computed tomography data of a 4.5-kg toy poodle were adjusted to simulate D/T ratios ranging from 0.5 to 2.0 and analyzed for von Mises stress, principal strain, safety factor, and fatigue life under standing, trotting, and jumping conditions. Increasing D/T ratios led to progressive rises in stress and compressive strain, with the safety factor falling below 1.0 during jumping at ratios of 1.0 or higher. Fatigue life declined sharply beyond a ratio of 1.25 and reached zero-cycle failure at 2.0. Complementary mechanical testing of six distal femurs (6.42–8.7 kg), surgically modified to D/T ratios of 0.5, 1.0, or 1.5, revealed fracture patterns consistent with finite element predictions. These findings suggest that excessive trochlear deepening may compromise femoral integrity and elevate fracture risk, particularly under cyclic loading. Maintaining a D/T ratio between 0.75 and 1.0 may provide an optimal balance between effective patellar tracking and mechanical safety. Full article

Chronic pain is the leading cause of disability worldwide and frequently co-occurs with mild traumatic brain injury among Veterans (mTBI + CP), creating complex treatment challenges and a need for novel, non-pharmacological interventions. This study evaluated a pilot intervention combining intermittent theta burst stimulation (iTBS), a neuromodulatory approach, with the evidence-based LoveYourBrain Yoga program to enhance rehabilitation outcomes. In a six-week open-label trial, ten Veterans with mTBI + CP received weekly iTBS followed by yoga sessions. Pilot quantitative outcomes included quality of life (Traumatic Brain Injury Quality of Life [TBI-QoL]) and functional ability (Mayo Portland Adaptability Inventory-4 [MPAI-4]), assessed pre- and post-intervention, alongside qualitative semi-structured interviews and interdisciplinary clinical notes. Significant improvements were observed in TBI-QoL Fatigue (p = 0.021) and MPAI-4 Grief and Loss (p = 0.016), with clinically meaningful but non-significant gains in Ability and Adjustment. Qualitative findings revealed improved pain management and enhanced self-management, with participants describing better emotional regulation, more effective coping strategies, and stronger social connections. Some benefits were more evident in qualitative data than in standardized measures. These pilot findings suggest that combining iTBS with mind–body therapy may provide complementary tools for pain management and functional recovery in Veterans with mTBI + CP, supporting further investigation of integrated neuromodulation and behavioral interventions. Full article

To address the strong variability, complex cyclic characteristics, and difficulty in characterizing the main shaft torque load of vertical ring-die biomass briquetting machines, this study proposes a random load spectrum generation method based on kernel density estimation (KDE) and a Copula function. The measured torque time-history signal was processed using wavelet-threshold denoising and rainflow counting to extract cycle mean and cycle amplitude samples. KDE was used to estimate their marginal distributions, and a Copula function was introduced to construct the joint distribution model. The random load spectrum was then reconstructed through two-dimensional probability integration based on the fitted joint density function. The results show that the Frank Copula best describes the dependence structure between the cycle mean and the cycle amplitude. The reconstructed load spectrum agrees well with the measured load spectrum in terms of marginal frequency distribution and main peak intervals, with an RMSE of 6.3161 and an NRMSE of 6.94%. Compared with the KDE-independent baseline model, the proposed KDE–Frank Copula model reduces the RMSE by 12.74%. These results indicate that the proposed method can effectively characterize the statistical features of the random torque load of the main shaft and provide methodological support for load spectrum generation, fatigue life prediction, and reliability design of vertical ring-die biomass briquetting machines. Full article

Purpose—The flexspline of a harmonic drive constitutes a thin-walled structure with discontinuous gear rim and cylinder configuration, where cyclic stresses induce stress concentration, followed by crack initiation, propagation, and ultimately fatigue failure. This paper reviews advancements in understanding its mechanical properties and fatigue failure mechanisms, aiming to establish a foundation for enhancing operational longevity and guiding future research. Design/Methodology/Approach—The study integrates meshing theory, tooth shape parameters, cylinder stress influencers, and assembly/meshing stress considerations. Theoretical analysis, finite element simulations, and experimental methods are employed to examine stress patterns and fatigue dynamics. Structural parameters and tooth profiles are systematically analyzed for their impact on stress distribution and fatigue life. Findings—Flexspline fatigue failure arises from tooth root stress concentration and cylinder bending stress accumulation. The double-circular-arc tooth profile boosts load capacity by 35% relative to the involute profile, yet demands high-precision machining to preserve meshing performance. Increasing cylinder length mitigates stress concentration but reduces torsional stiffness, while optimized root fillet radii can lower the stress concentration coefficient by 28%. Assembly interference and meshing contact stress accelerate crack initiation, as validated by transient dynamics simulations. Surface strengthening processes (e.g., shot peening) enhance fatigue life by up to 66% through residual compressive stress regulation. Originality/Value—This paper synthesizes multi-scale research on flexspline design, structural optimization, and fatigue mechanisms, proposing novel approaches such as “manufacturability-oriented optimization” and digital twin-driven monitoring. By linking dynamic loads, material properties, and geometric parameters, it bridges theoretical gaps and provides actionable insights for high-precision harmonic drives in robotics and aerospace, advancing reliability in precision transmission systems. Full article