Passenger fuel cell vehicles (FCVs) require high-gain DC/DC converters to achieve voltage matching between the low-power fuel cell (FC) stack (50-200 V) and the vehicle DC bus (400-800 V). To address the challenges in existing step-up DC/DC converters in relation to balancing the requirements of high voltage gain, wide input voltage range, low input current ripple and voltage stress, the common ground of input-output, and high efficiency in passenger FCV applications, this paper proposes three types of high-gain DC/DC converters based on an interleaved structure, incorporating quadratic Boost, quasi-Z source, and switched-inductor impedance networks. These designs effectively balance the scenario requirements of passenger FCVs. Meanwhile, taking one of the proposed converters (Interleaved-Quadratic Boost; I-QB) as an example, its steady-state performance such as voltage gain is analyzed and compared in detail with existing voltage step-up DC/DC converters. Furthermore, a scaled-down SiC-based experimental platform is constructed. Steady-state experiments validate the converter's maximum voltage step-up capability of ten times, wide input voltage range of 30-80 V, input current ripple of less than 0.3 A, and low voltage stress on devices (<= Uo/2), thereby confirming the feasibility of these converters and the correctness of the performance analysis. The dynamic experimental results indicated that under input voltage step changes of 50-80 V and 100-50% load step changes, the I-QB converter exhibits a minor voltage overshoot with settling time under 200 ms. The prototype achieves a peak efficiency of 94.2%, confirming these converters' suitability for passenger FCV powertrains.
In this paper, a predator-prey model with a constant harvesting rate, fear effect, Holling Type II Function, and age structure is studied. Using algebraic methods, we derive all critical values for the two time delays at which the characteristic equation admits purely imaginary roots. This yields an explicit stability region in the parameter plane which corresponds to the positive equilibrium. By employing the integrated semigroup theory and the Hopf bifurcation theorem for abstract Cauchy problems with non-dense domains, we establish that the Hopf bifurcation occurs when the time delays cross these critical values. Notably, stability switches can also be observed as the delays vary. Finally, numerical simulations are performed to verify our analytical results.
Digital libraries increasingly use cloud-edge infrastructures to safely and effectively handle and communicate enormous amounts of academic material as 5G and 6G networks evolve. Existing cloud-only designs still have capacity constraints during peak transmission, fragmented data distribution that slows retrieval, and inadequate real-time threat detection. The proposed KSEdge-Trust framework addresses this gap with an edge-oriented, security-aware knowledge-sharing architecture for next-generation library big-data settings. The framework uses Edge-Centric Knowledge Orchestration for locality-aware data partitioning, an Adaptive Trust Layer with blockchain-based consensus for integrity assurance, and a Secure Transmission Optimizer for lightweight encryption and intelligent traffic regulation to speed delivery. Compared to cloud-only systems, KSEdge-Trust reduces end-to-end latency by 47%, improves retrieval efficiency by 39%, and raises threat-detection accuracy by 92%, attaining 300 ms and 95% retrieval efficiency. These performance gains confirm the framework's capability to deliver secure, scalable, and high-performing knowledge dissemination within advanced 5G/6G cloud-edge ecosystems.
Biochar amendment is an effective strategy for mitigating methane (CH4) emissions in paddy fields. However, the long-term efficacy of different biochar amendment strategies for mitigating CH4 emissions remains unclear, particularly under different water management regimes. To address this knowledge gap, a 5-year (2018–2022) field experiment was conducted to determine CH4 production potential, CH4 oxidation potential, and CH4 emissions in paddy fields under six treatments: flooded irrigation (F) without biochar amendment (FB0), F with once biochar amendment (12.5 t ha−1, FB1), F with continuous biochar amendment (2.5 t ha−1 year−1, FB5), controlled irrigation (C) without biochar amendment (CB0), C with once biochar amendment (12.5 t ha−1, CB1), and C with continuous biochar amendment (2.5 t ha−1 year−1, CB5). Additionally, random forest analysis and structural equation modeling (SEM) were used to elucidate interaction pathways among biochar amendment, water management, CH4 production and oxidation potentials, and key soil properties affecting CH4 emissions. In the first year, once biochar amendment demonstrated optimal CH4 mitigation efficacy under different water management regimes, reducing cumulative CH4 emissions by 18.87–36.32 NH^+_4-N ) as key soil properties driving CH4 emissions. CB5 maintained higher soil Eh and NH^+_4-N levels with lower DOC, leading to the lowest CH4 production potential and highest CH4 oxidation potential over 5 years, ultimately achieving the greatest CH4 mitigation. Furthermore, CB5 achieved the lowest CH4-attributed greenhouse gas intensity and net greenhouse gas emissions over 5 years. These findings highlight the necessity of long-term monitoring to accurately assess the effects of biochar amendments on CH4 mitigation and offer technical guidance for implementation of biochar strategies in paddy fields under different water management regimes. Highlights
Background:Physical activity is widely promoted as a cornerstone of healthy ageing; however, this assumption largely derives from leisure-time exercise and may not apply to labour-dependent older populations. In rural settings, occupational physical activity (OPA) is often necessity-driven, prolonged, and embedded within structural constraints, yet its associations with metabolic and vascular outcomes in later life remain poorly understood. Methods:We conducted a community-based cross-sectional study of 2,258 adults aged ≥65 years from a representative agricultural region in Northeast China. Labour-type physical activity was classified as inactive, moderate, or high intensity. To mitigate underdiagnosis, we defined total diabetes burden as either diagnosed diabetes or undiagnosed hyperglycemia. Systemic insulin resistance was assessed using the triglyceride-glucose (TyG) index. Urine occult blood (UOB) positivity was analyzed as an exploratory marker compatible with physiological stress. Associations were examined using modified Poisson regression with robust variance, robust linear regression, and prespecified sensitivity analyses. Results:High-intensity labour was associated with a modest reduction in insulin resistance among individuals without diagnosed diabetes (β = -0.079, p = 0.005) and a lower prevalence of undiagnosed hyperglycemia (PR 0.69, 95% CI 0.53-0.88). In contrast, high-intensity labour was more common among individuals with diagnosed diabetes (PR 1.43, 95% CI 1.11-1.85). These opposing associations did not show a significant net association with total diabetes burden (PR 0.99, p = 0.912). Independently of metabolic status, high-intensity labour was associated with a higher prevalence of UOB positivity (PR 1.25, 95% CI 1.09-1.44). Conclusion:In labour-dependent rural older adults, heavy occupational labour may not confer metabolic benefit at the population level and is independently associated with a microvascular stress-related signal. This "Futile Labour Paradox" challenges the assumption that physical activity is uniformly beneficial in later life and underscores the need to distinguish occupational labour from discretionary exercise.
