Search Results (715)

Heavy rainfall infiltration is a key disaster-inducing factor that triggers the softening of surrounding rock and deformation of support structures in tuff gully tunnels. Based on the gully section of the left line of the Dabao Tunnel of the Leigongshan–Rongjiang Expressway in Guizhou Province, this study systematically reveals the synergistic disaster-inducing mechanism of “topography-seepage-softening” in tuff gully tunnels under heavy rainfall infiltration through laboratory tests and FLAC3D 3D numerical simulations. The main innovative conclusions are as follows: (1) The “phased” attenuation law of tuff mechanical parameters was quantified, and the critical water content for significant strength deterioration was determined to be 2.5%, with a saturated softening coefficient of 0.59. These results provide key data for early warning and evaluation of similar projects. (2) A “convergence-disorder” distribution pattern of pore water pressure controlled by gully topography was revealed. It was found that the rock mass directly below the aqueduct exhibits a disordered zone with downward-extending pore water pressure due to fluid convergence, with the maximum pore water pressure reaching 0.55 MPa. This clarifies the essence that tunnel stability is controlled by the coupling of topography and seepage field. (3) The key sensitive areas for tunnel stability—namely the gully bottom, arch haunches, and the area below the aqueduct—were accurately identified. The significant increase in displacement of these areas after rock stratum softening was quantified (e.g., the displacement at the crown of the secondary lining increased from 3 mm to 4 mm, and the influence range expanded to the arch haunches). This study clarifies the deformation characteristics and instability mechanism of tuff gully tunnels under heavy rainfall from two aspects: the “internal mechanism of rock mass softening” and the “external condition of topographic seepage control.” It can provide a theoretical basis and key technical pathway for disaster prevention and control as well as stability design of similar tunnels. Full article

Flavonoids, a ubiquitous class of plant secondary metabolites, are increasingly pivotal as chemical markers for ensuring the quality, safety, and efficacy of herbal medicines (HMs). Their broad distribution, biological activities, and detectability make them ideal for this role. This comprehensive review critically examines current trends and analytical perspectives regarding flavonoids in HM quality control. We first explore advanced quality control strategies that move beyond single-compound quantification, including chemical fingerprinting, metabolomics, network pharmacology, and the innovative concept of Q-markers. The review then provides an in-depth analysis of the analytical techniques central to flavonoid analysis, from the routine use of HPTLC and HPLC-UV to advanced hyphenated systems like UHPLC-QTOF-MS, highlighting their applications in authentication, standardization, and adulteration detection. Furthermore, we emphasize the growing importance of modern data analysis workflows, particularly the integration of chemometrics and molecular networking, for interpreting complex datasets and identifying robust, bioactivity-relevant markers. By synthesizing recent research (2017–2024), this work underscores a paradigm shift towards holistic, multi-marker approaches and data-driven methodologies. It concludes that the synergistic application of advanced analytical techniques with sophisticated data modeling is essential for the future of HM quality control, ensuring reliable and standardized herbal products for global consumers. Full article

The mixed metal oxides (MMOs) derived from layered double hydroxides (LDHs) are a typical class of porous materials and have attracted significant attention across various fields due to their high surface area, rich porous structures and various compositions. Regulating the pore structure of MMOs remains an urgent need because of the growing demand for numerous applications including adsorption, catalysis, and energy conversion. Controlling the lateral size of the lamellar crystals in the Co–Al LDH precursor allowed us to engineer the pore structure of Co–Al MMO, an architecture formed by the stacking of these lamellar flakes. The pore size distribution of the Co–Al MMO has been adjusted in the range from several nanometer to hundreds of nanometers. The sample with the optimized pore sizes exhibited a much higher catalytic reaction rate in the aerobic oxidation reaction of benzyl alcohol, about 4.2 times that of the control sample. Further research demonstrated that the high activity was favored by the improved mass transfer rate in the optimized pore architecture. Moreover, sodium silicate was employed as a cross-linking agent to enhance the cohesion within the secondary particles, which consist of stacked lamellar flakes. The resulting silicate-modified Co–Al MMO demonstrated significantly improved catalytic durability, maintaining stable performance over five consecutive reuse cycles—the performance that substantially exceeded that of its un-modified counterpart. Full article

The seepage characteristics and heat transfer efficiency in rough fractures are indispensable for assessing the lifetime and production performance of geothermal reservoirs. In this study, a two-dimensional rough rock fracture model with different secondary roughness is developed using the wavelet analysis method to simulate the coupled flow and heat transfer process under multiscale roughness based on two theories: local thermal equilibrium (LTE) and local thermal nonequilibrium (LTNE). The simulation results show that the primary roughness controls the flow behavior in the main flow zone in the fracture, which determines the overall temperature distribution and large-scale heat transfer trend. Meanwhile, the nonlinear flow behaviors induced by the secondary roughness significantly influence heat transfer performance: the secondary roughness usually leads to the formation of more small-scale eddies near the fracture walls, increasing flow instability, and these changes profoundly affect the local water temperature distribution and heat transfer coefficient in the fracture–matrix system. The eddy aperture and eddy area fraction are proposed for analyzing the effect of nonlinear flow behavior on heat transfer. The eddy area fraction significantly and positively correlates with the overall heat transfer coefficient. Meanwhile, the overall heat transfer coefficient increases by about 3% to 10% for eddy area fractions of 0.3% to 3%. As the eddy aperture increases, fluid mixing is enhanced, leading to a rise in the magnitude of the local heat transfer coefficient. Finally, the roughness characterization was decomposed into primary roughness root mean square and secondary roughness standard deviation, and for the first time, an empirical correlation was established between multiscale roughness, flow velocity, and the overall heat transfer coefficient. Full article

Proximal humerus fractures are frequent injuries that often require internal fixation. Conventional metallic plates, however, present significant drawbacks such as corrosion, secondary removal surgeries, and adverse reactions in patients with metal hypersensitivity. This study evaluates biocomposite plates fabricated from polylactic acid (PLA) and polyvinyl alcohol (PVA), reinforced with hydroxyapatite (HA) derived from sugar industry by-products (BCF) at 10% and 20% concentrations. These composites are compatible with both injection molding and 3D printing, enabling the design of patient-specific implants. Characterization by SEM, FTIR, XRD, and DSC confirmed that BCF incorporation enhances strength, stiffness, osteoconductivity, and biocompatibility. Mechanical testing showed that PVA/BCF exhibited greater tensile strength and stiffness, suggesting suitability for load-bearing applications, though their water solubility restricts use in humid environments and prevents filament-based 3D printing. PLA/BCF composites demonstrated better processability, favorable mechanical performance, and compatibility with both manufacturing routes. Finite element analysis highlighted the importance of plate–humerus contact in stress distribution and fixation stability. Compared with non-biodegradable thermoplastics such as PEI and PEEK, PLA/BCF and PVA/BCF offer the additional advantage of controlled biodegradation, reducing the need for secondary surgeries. Cell viability assays confirmed cytocompatibility, with optimal outcomes at 10% BCF in PVA and 20% in PLA. These results position PLA/BCF and PVA/BCF as sustainable, patient-tailored alternatives to metallic implants, combining adequate mechanical support with bone regeneration potential. Full article

Aiming at the challenges of design complexity and parameter adjustment difficulties in existing distributed controllers, a novel power flow sensitivity-based distributed cooperative control approach is proposed for voltage regulation and power sharing in droop-controlled DC distribution networks (DCDNs). Firstly, based on the power flow model of droop-controlled DCDNs, a comprehensive sensitivity model is established that correlates bus voltages, voltage source converter (VSC) loading rates, and VSC reference power adjustments. Leveraging the sensitivity model, a discrete-time linear state-space model is developed for DCDNs, using all VSC reference power as control variables, along with the weighted sum of the voltage deviation at the VSC connection point and the loading rate deviation of adjacent VSCs as state variables. A distributed consensus controller is then designed to alleviate the communication burden. The feedback gain design problem is formulated as an unconstrained multi-objective optimization model, which simultaneously enhances dynamic response speed, suppresses overshoot and oscillation, and ensures stability. The model can be efficiently solved by global optimization algorithms such as the genetic algorithm, and the feedback gains can be designed in a systematic and principled manner. The simulation results on a typical four-terminal DCDN under large power disturbances demonstrate that the proposed distributed control method achieves rapid voltage recovery and converter load sharing under a sparse communication network. The design complexity and parameter adjustment difficulties are greatly reduced without losing the control performance. Full article

The growing demand for precision and consistency in the forging industry has heightened the need for predictive simulation tools. While extensive research has focused on parameters such as flow stress, die wear, billet fracture, and residual stresses, the phenomenon of billet buckling, especially during cold upset forging, remains underexplored. Most existing models address only elastic buckling for slender billets using classical approaches like Euler and Rankine-Gordon formulae, which are not suitable for inelastic deformation in shorter billets. This study presents a numerical model developed to analyze inelastic buckling during cold forging and to determine associated stresses and deflection characteristics. The model was validated through finite element simulations across a range of billet geometries (10–40 mm diameter, 120 mm length), materials (aluminum, stainless steel, and copper), and friction coefficients (µ = 0.12, 0.16, and 0.35). Stress distributions were evaluated against die stroke, with particular emphasis on the influence of strain hardening and geometry. The results showed that billet geometry and strain-hardening exponent significantly affect buckling behavior, whereas friction had a secondary effect, mainly altering overall stress levels. A nonlinear regression approach incorporating material properties, geometric parameters, and friction was used to formulate the numerical model. The developed model effectively estimated buckling stresses across various conditions but could not precisely predict buckling points based on stress differentials. This work contributes a novel framework for integrating material, geometric, and process variables into stress prediction during forging, advancing defect control strategies in industrial metal forming. Full article

To address the stability control challenges of narrow coal pillar roadways along goaf-sides affected by thick coal seam secondary mining, this study investigates the 51507 track gateway in Liuyuanzi Coal Mine through theoretical analysis, numerical simulation, and field testing. The research focuses on stress evolution and energy distribution characteristics during secondary mining extraction. Key findings include the following: (1) Under the superimposed influence of goaf-side abutment pressure and secondary mining front abutment pressure, roadway surrounding rock exhibits regional asymmetric characteristics in energy dissipation. (2) Within 10 m ahead of the secondary mining face, the coal pillar experiences intense energy dissipation and plastic zone penetration, leading to bearing structure failure. (3) The energy mechanism reveals that asymmetric dissipative energy distribution drives plastic zone expansion. Accordingly, an integrated control strategy combining differentiated support (bolts/cables + tension-type opposite anchor cables + hydraulic props) with coal pillar grouting modification was developed. Field implementation demonstrated effective control of surrounding rock deformation within 200 mm. This study provides theoretical foundations and technical references for roadway stability control under similar mining conditions. Full article

Current ringing in dual-active bridge (DAB) converters significantly degrades efficiency and reliability, particularly due to resonant interactions in the magnetic tank impedance network. We propose a novel impedance resonant channel shaping technique to suppress the ringing by systematically modifying the converter’s equivalent impedance model. The method begins with establishing a high-fidelity network representation of the magnetic tank, incorporating transformer parasitics, external inductors, and distributed capacitances, where secondary-side components are referred to the primary via the turns ratio squared. Critical damping is achieved through a rank-one modification of the coupling denominator, which is analytically normalized to a second-order form with explicit expressions for resonant frequency and damping ratio. The optimal series–RC damping network parameters are derived as functions of leakage inductance and winding capacitance, enabling precise control over the effective damping factor while accounting for core loss effects. Furthermore, the integrated network with the damping network dynamically shapes the impedance response, thereby attenuating ringing currents without compromising converter dynamics. Experimental validation confirms that the proposed approach reduces peak ringing amplitude by over 60% compared to the conventional snubber-based methods, while maintaining full soft-switching capability. Full article

Groundwater serves as a vital water resource for agricultural irrigation and domestic use in farmland areas. Its chemical composition is jointly influenced by agricultural fertilization, land use practices, and natural geological processes. However, research on the controlling factors and spatial distribution characteristics of groundwater hydrochemistry in agricultural regions remains insufficient. In this study, 56 groundwater samples were collected from the central-eastern plain of Henan Province, China. A combination of hierarchical cluster analysis, ionic ratio methods, principal component analysis, and kriging interpolation was employed to investigate the hydrochemical characteristics, spatial patterns, and primary controlling factors of regional groundwater. The results indicate that the first group of samples is characterized by high total dissolved solids (TDS), elevated Na⁺ and Cl⁻ concentrations, predominantly controlled by evaporation and concentration processes. The second group exhibits high pH and low Ca²⁺ concentrations, mainly influenced by silicate weathering, with reverse cation exchange acting as a secondary controlling process. The third group is characterized by elevated concentrations of Ca²⁺ and NO₃⁻, primarily controlled by carbonate weathering and agricultural activities. The western part of the study area serves as the main groundwater recharge zone and has the highest NO₃⁻ and Ca²⁺ concentrations. In the central area, most ion concentrations are relatively high, forming a distinct gradient with surrounding regions. Meanwhile, the eastern area displays elevated concentrations of HCO₃⁻, TDS, Na⁺, and Cl⁻, highlighting pronounced spatial heterogeneity. Overall, the hydrochemical composition of groundwater in the study area is shaped by both natural processes and anthropogenic activities, exhibiting significant spatial heterogeneity. Notably, the spatial variation of NO₃⁻ concentrations is substantial, indicating that certain localities have already been affected by agricultural non-point source pollution. Full article

Non-equipotentiality in a grounding device can cause thermal heating in the screens of control cables that are grounded on both sides of high-voltage substations. At the same time, there is currently no approach for assessing the thermal endurance of cable screens that takes into account the configuration of the grounding device, the properties of the ground, and the connection. This paper presents a methodology for the experimental and computational determination of the thermal endurance of control cable shields in secondary circuits of 220–500 kV substations under short-circuit (SC) conditions. The method is based on full-scale imitation experiments using a sinusoidal current generator and verified numerical modeling in the ORU-M software. The potential and current density distribution in the cable shields were determined. The results showed that current densities in some circuits exceed permissible levels, confirming the risk of thermal damage. It was found that reconfiguring the grounding system—by densifying ground electrodes and increasing connections between grounding points—can reduce current density to acceptable values. The presented method allows for reliable assessment of the thermal endurance of cable shields without decommissioning the substation, making it suitable for the design and modernization of high-voltage facilities. Full article

A novel long-lasting luminescent composite material based on the (Ca,Sr)-Al-O system was synthesized using a solution combustion method. (Ca,Sr)₃Al₂O₆ is the primary phase, with SrAl₂O₄ as a controllable secondary phase. Compared to conventional single-phase SrAl₂O₄ phosphors, the introduction of a calcium-rich hexaaluminate matrix creates additional defects and a specific trap distribution at the composite interface, significantly improving carrier storage and release efficiency. Eu²⁺ + Nd³⁺ synergistic doping enables precise control of the trap depth and number. Under 365 nm excitation, Eu²⁺ emission is located at ~515 nm, with Nd³⁺ acting as an effective trap center. Under optimal firing conditions at 700 °C (Eu²⁺ = 0.02, Nd³⁺ = 0.003), the afterglow lifetime exceeds 30 s. Furthermore, The (Ca,Sr)₃Al₂O₆ host stabilizes the lattice and optimizes defect states, while synergizing with the SrAl₂O₄ secondary phase to improve the afterglow performance. This composite phosphor exhibits excellent dual-mode anti-counterfeiting properties: long-lasting green emission under 365 nm excitation and transient blue-violet emission under 254 nm excitation. Based on this, a screen-printing ink was prepared using the phosphor and ethanol + PVB, enabling high-resolution QR code printing. Pattern recognition and code verification can be performed both in the UV on and off states, demonstrating its great potential in high-security anti-counterfeiting applications. Compared to traditional single-phase SrAl₂O₄ systems, this study for the first time constructed a composite trap engineering of the (Ca,Sr)₃Al₂O₆ primary phase and the SrAl₂O₄ secondary phase, achieving the integration of dual-mode anti-counterfeiting functionality with a high-resolution QR code fluorescent ink. Full article

In an attempt to improve utilization of the frequency spectrum left vacant by license holders, cognitive radio networks (CRNs) permit secondary users (SUs) to utilize such spectrum when the license holders, known as primary users (PUs), are inactive. When a pair of SUs wants to communicate over the CRN, they need to converge simultaneously on one of the vacant channels, in a process known as rendezvous. In this work, we attempt to reduce the rendezvous time for SUs executing the well-known enhanced jump-stay (EJS) channel hopping procedure. We achieve this by modifying EJS in order to search the vacant spectrum around a specific favorite channel, instead of hopping across the whole spectrum. Moreover, the search process is carefully designed in order to accommodate the dynamic nature of CRNs, where PUs repeatedly become active and inactive, resulting in disturbances to the rendezvous process. A main feature of our proposed technique, named dynamic jump-stay (DJS), is that the SUs do not need any prior coordination over a common control channel (CCC), thereby allowing for scalable and more robust distributed CRNs. Simulations are used to quantify the resulting performance improvement in terms of expected time to rendezvous, maximum time to rendezvous, and interference on PUs. Full article

Background/Objectives: Bullous pemphigoid (BP) is a manageable condition, and the primary goal of treatment is to control the disease while minimizing the use of corticosteroids due to their potential side effects with long-term use. The primary aim of this study was to assess the effectiveness of omalizumab (OMZ) treatment in bullous pemphigoid patients using both objective and subjective indicators, including bullous pemphigoid disease area index (BPDAI) score, peripheral eosinophil count, serum total IgE level, systemic corticosteroid dosage, and pruritus severity (VAS pruritus). The secondary aim was to explore potential predictors of treatment response, such as baseline BPDAI, age, gender, lesion distribution, serum total IgE, peripheral eosinophil count, maximum and minimum corticosteroid dose, and comorbidities, as well as to evaluate the time to clinical response and corticosteroid tapering. Methods: This retrospective analysis included 25 BP patients treated with OMZ as add-on therapy to systemic corticosteroids between January 2023 and December 2024 at Health Sciences University, Başakşehir Çam and Sakura Training and Research Hospital, Dermatology and Venerology Clinic. No other systemic immunosuppressants were permitted. All patients were already receiving systemic corticosteroids at enrolment. This retrospective analysis included 25 BP patients receiving omalizumab (300 mg/4 weeks) as an add-on to systemic corticosteroids, initiated primarily for steroid-refractory disease and/or persistent, sleep-disrupting pruritus. Baseline was defined immediately before the first OMZ dose; assessments were performed at baseline and week 12. Clinical (BPDAI, VAS pruritus) and laboratory (eosinophil count, total IgE levels) parameters were assessed at baseline and week 12. Results: OMZ treatment significantly reduced disease severity, as evidenced by a mean decrease in the BPDAI score of 105.0 ± 48.9 (95% CI 84.8–125.2) compared to baseline (p < 0.001). Peripheral eosinophil count also decreased by 0.6 ± 0.3 (95% CI 0.4–0.7) after treatment (p < 0.001). Total serum IgE levels declined significantly in 92% of patients (95% CI 244.5–2171.3) compared to pretreatment (p < 0.001), although two patients (8%) showed an increase (202.0 ± 258.8) after OMZ treatment. OMZ treatment led to a mean systemic corticosteroid dose reduction of 37.0 ± 14.1 mg (95% CI 31.1–42.8 mg), with a median corticosteroid tapering time of 4 weeks (3.0–4.0). Additionally, pruritus severity, measured by pruritus VAS, decreased by 6.2 ± 1.4 (95% CI 5.6–6.7) following treatment (p < 0.001). OMZ was well tolerated, with no serious adverse events. Conclusions: Within a 12-week observation window, we observed improvements in disease activity and pruritus alongside reduced corticosteroid exposure. Given the retrospective, uncontrolled add-on design, these findings do not establish causality but support further prospective controlled evaluation of omalizumab as a steroid-sparing option. Importantly, OMZ treatment significantly reduced the mean corticosteroid dose, pruritus VAS score, total IgE levels, and eosinophil count, indicating therapeutic activity and supporting its use as an effective steroid-sparing option in the management of bullous pemphigoid. Full article

High impedance grounding faults (HIGFs) are a common yet difficult-to-detect issue in distribution networks. Characterized by low fault currents and prolonged durations, they pose a significant risk of triggering secondary hazards such as wildfires. Existing HIGF prevention and control technologies face challenges in effectively addressing arc ignition, fault current limitation, and wildfire mitigation. To tackle these limitations, this paper proposes a novel asymmetric operational structure incorporating a single-phase isolation transformer and supplementary edge-phase capacitance. Through theoretical modeling and simulation analysis, the interrelations among fault current, phase voltage, zero-sequence voltage, and HIGF characteristics are systematically explored. A coordinated control strategy is developed to optimize three-phase voltage distribution within the distribution network. Simulation results demonstrate that the proposed configuration significantly reduces edge-phase voltages, suppresses fault current levels, prevents arc initiation, extends arc ignition delay times, and consequently mitigates wildfire risk. This study presents a new technical pathway for HIGF prevention and control, offering both practical engineering value and theoretical insight. Full article