Search Results (7,053)

DC distribution systems are increasingly utilized in data centers, electric vehicle charging infrastructures, and microgrids due to their superior power conversion efficiency compared to AC systems. In DC networks, the protection coordination of overcurrent relays (OCRs) is essential for selectively isolating faults and maintaining operational stability. However, the integration of distributed energy resources (DERs), such as photovoltaics, introduces significant challenges by altering the magnitude and rate of change of fault currents. This study conducts a comprehensive analysis of various scenarios by varying both the fault location and the points of common coupling (PCC) for DER. The simulation results reveal that specific configurations lead to critical instances of protection mis-operation and failure to operate, which cause coordination failures and compromised coordination time intervals (CTIs). These findings demonstrate that conventional protection strategies may fail to ensure reliability in DER-integrated DC systems due to the dynamic nature of fault current characteristics. In this paper, these diverse scenarios and the resulting vulnerabilities in protection coordination were modeled and verified using PSCAD/EMTDC V5.0. Full article

This paper presents a lightweight method for assessing the resilience of power distribution systems that integrates climate and infrastructure data through impact chains and a probabilistic approach, while minimizing data integration and implementation complexity. The method is demonstrated for heatwave hazards by combining network characteristics, failure probabilities of heat-sensitive components (e.g., medium-voltage cable joints), and location-specific climate projections to generate spatial maps of failure risk and network resilience. These maps support the identification and prioritization of critical components requiring intervention. Critical segments are then further analyzed using probabilistic resilience metrics to compare alternative adaptation strategies. Overall, this work contributes a practically applicable, low-complexity methodology for identifying the weakest portions of distribution networks, along with a more in-depth probabilistic approach for assessing their climate resilience. The com-prehensive framework is illustrated through a case study of a representative portion of the Italian electricity distribution system in the urban area of Rome. It is implemented in a test environment that reflects realistic distribution network data structures and automatically integrates climate data from established online repositories. Full article

Introduction: Major Depressive Disorder (MDD) has been increasingly associated with inflammatory dysregulation, particularly involving tumor necrosis factor-alpha (TNF-α). Genetic polymorphisms within the TNFA promoter region have been investigated as potential modulators of depressive susceptibility, symptom expression, treatment response, and inflammatory comorbidity. However, findings remain inconsistent across populations and clinical contexts. Methods: This systematic review adhered to PRISMA 2020 guidelines and was registered in PROSPERO (CRD420251242724). Observational and interventional studies evaluating associations between TNFA polymorphisms—specifically rs1800629 (−308 G/A), rs1799724 (−857 C/T), and rs1799964 (−1031 T/C)—and MDD-related outcomes in adults were included. Data extraction and methodological quality assessment were performed independently using an adapted GRIPS framework. Results: Eleven studies met the inclusion criteria, with eight investigating MDD without cardiovascular comorbidity and three assessing cardiovascular populations. Across diverse cohorts, rs1800629 and rs1799724 did not demonstrate consistent associations with MDD susceptibility. Although isolated population-specific findings were reported, genotype and allele distributions were generally comparable between cases and controls. Rs1799724 was associated with symptom dimensions and altered TNF-α expression in two cohorts. Rs1799964 was not linked to disease occurrence but showed potential association with antidepressant response and adverse cardiovascular outcomes in patients with chronic heart failure and comorbid depression. Overall, findings were heterogeneous and influenced by population characteristics, sample size, and clinical context. Conclusions: Current evidence does not support a robust etiological role for TNFA promoter polymorphisms in major depressive disorder. These variants may exert context-dependent modulatory effects on symptom expression, treatment response, or inflammatory-cardiovascular interactions rather than serving as primary susceptibility determinants. Larger, ethnically diverse studies integrating genetic, inflammatory, and clinical data are required to clarify the contribution of inflammatory genetic variability in depressive disorders. Full article

With the acceleration of urbanization, deep and large foundation pit projects have become increasingly common, posing challenges for retaining structural performance. This study investigates the mechanism of the recently proposed vertical–inclined pile wall (VIPW) through physical model tests. Six sets of large-scale model tests of foundation pit excavation under 1 g gravity conditions were carried out. Among these tests, one employed the soldier pile wall (SPW) as the support system, while the remaining five adopted the VIPW. By monitoring and analyzing the distribution and variation in the vertical pile deformation, surface settlement, pile bending moment, and inclined pile top axial force during the excavation process, the action mechanism of the VIPW was revealed, and it was verified that VIPWs exhibit better support performance than SPWs. Furthermore, four key parameters, including the embedded depth, the inclination angle, the support position of the inclined piles, and the embedded depth of the vertical piles, were varied to study their influence on the deformation and force characteristics of the VIPW, providing a theoretical basis for structural optimization design. Moreover, by comparing the instability and failure characteristics of the foundation pit, it was proved that the VIPW can effectively ensure the stability of the foundation pit. Full article

Deep shale of the Lower Cambrian Qiongzhusi Formation in the Sichuan Basin represents a critical frontier for shale gas exploration in China. However, systematic understanding of the multi-scale links among lamination type, mechanical anisotropy, and fracture complexity remains limited. Based on lamination characteristics and total organic carbon (TOC) content, core samples were classified into four types. Using a multi-scale approach (uniaxial compression, Brazilian splitting, in situ CT scanning, QEMSCAN, and SEM), this study elucidates how lamination structure controls mechanical anisotropy, failure modes, and fracture mechanisms. The novelties of this work are threefold: (1) quantitatively linking specific lamination types (ORM, OPM, PAFC, PAF) to anisotropic mechanical responses; (2) introducing 3D fractal dimensions to evaluate fracture network complexity; and (3) integrating micro- (SEM) and macro-scale tests to reveal the coupled control of weak planes and brittle minerals on fracture propagation. Results indicate that laminated shales exhibit pronounced mechanical anisotropy. Loading parallel to laminations induces tensile splitting along weak planes, significantly reducing strength. Conversely, perpendicular loading generates complex fracture networks of horizontal secondary fractures along laminae and vertical main fractures through the matrix. Furthermore, 3D fractal dimension analysis quantifies fracture network complexity as follows: organic-poor clay-feldspar laminated shale > organic-poor clay-feldspar-calcareous laminated shale > organic-rich massive shale. Microscopic observations confirm that fracture propagation is jointly governed by weak plane systems and brittle mineral content, which collectively determine macroscopic failure patterns. These findings clarify how lamination type controls the laboratory mechanical response and fracture morphology of deep shale and provide a laboratory-scale framework for comparing lamination-related differences in mechanical anisotropy and fracture complexity in the Qiongzhusi Formation. Full article

The rheological behavior of rock masses governs long-term stability, yet the time-dependent properties of grouted structural planes remain insufficiently quantified. Graded shear creep tests were conducted on artificially split sandstone structural planes with controlled grout thicknesses, complemented by scanning electron microscopy (SEM), to clarify creep evolution and long-term shear strength. The results show that the total shear creep displacement of grouted specimens exhibits limited sensitivity to grout thickness, while the ratio of long-term to theoretical shear strength increases by approximately 10% at a grout thickness of 2 mm; this strengthening effect, however, diminishes at greater thicknesses. Moreover, the creep rate evolution of grouted specimens differs fundamentally from that of ungrouted specimens, with about 60% of grouted samples exhibiting an accelerated creep stage characterized by a U-shaped rate curve. The failure mode shifts from asperity-controlled slip in ungrouted structural planes to damage concentrated at the grout–rock interface in grouted specimens. SEM observations further reveal that micro-defects at this interface initiate and propagate cracks, ultimately governing the macroscopic creep failure process. Overall, this study establishes an isochronous curve-based method for determining long-term strength and demonstrates that interface micromechanics critically control the long-term performance of grouted rock masses. These findings provide practical guidance for grouting reinforcement in underground engineering. Full article

Background: Heart failure (HF) is a chronic condition associated with frequent hospitalizations and impaired quality of life. Malnutrition is common in HF and is linked to adverse clinical outcomes, while self-care is an important component of HF management. This study aimed to examine the associations between nutritional status, self-care behaviors, and clinical characteristics in patients with chronic HF. Methods: A cross-sectional study was conducted among 100 hospitalized HF patients (mean age 75.9 ± 9.8 years; 63% men). Nutritional status was assessed using the Mini Nutritional Assessment (MNA), and self-care using the nine-item European Heart Failure Self-care Behaviour Scale (9-EHFScBS). Clinical variables included NYHA class, LVEF, comorbidities, BMI, and laboratory parameters. Comparative analyses and multivariate linear regression were performed. Results: Patients who were malnourished or at risk of malnutrition had significantly higher NT-proBNP levels (p = 0.004) and higher NYHA class (p = 0.002), whereas well-nourished individuals had significantly higher triglyceride levels (p = 0.032). Nutritional status was negatively associated with NYHA class and NT-proBNP, and positively associated with BMI. Among laboratory parameters, significant positive correlations were observed with hemoglobin, hematocrit, albumin, and triglyceride levels. In multivariate analysis, the following variables were independently associated with MNA score: self-care score (B = 0.083 per point), BMI (B = 0.368 per kg/m²), comorbidity burden (B = −0.401 per comorbidity), and NYHA class (NYHA III: B = −2.425; NYHA IV: B = −5.966, vs. NYHA II). Conclusions: In patients with chronic heart failure, nutritional status is associated with disease severity, metabolic parameters, comorbidity burden, BMI, and self-care behaviors. These findings support the importance of routine nutritional screening as part of comprehensive HF management. Full article

The nominal maximum aggregate size (NMAS) plays a critical role in determining the mechanical performance of cement-stabilized macadam (CSM), yet its meso-mechanical influence mechanism remains insufficiently understood. In this study, three skeleton-dense CSM mixtures with different NMAS values were designed, and a combined experimental–numerical approach was adopted to investigate the macro- and meso-scale mechanical behavior. Uniaxial compression tests and aggregate crushing value tests were conducted to evaluate strength development and load-transfer characteristics, while a three-dimensional discrete element method (DEM) model incorporating realistic aggregate morphology was established to analyze the evolution of contact forces and crack propagation. The results show that increasing NMAS significantly improves the mechanical performance of CSM. Compared with CSM-30, the 7-day compressive strength of CSM-40 and CSM-50 increased by approximately 10.3% and 37.3%, respectively. The stress–strain response indicates that mixtures with larger NMAS exhibit higher stiffness and a higher strain. At the meso-scale, a larger NMAS promotes the formation of a more efficient force-chain network dominated by coarse aggregates. Strong contacts were predominantly carried by aggregates larger than 9.5 mm, and in CSM-50, the proportion of strong contacts in the 37.5–53 mm fraction exceeded 90%, indicating that the largest particles likely form the primary load-bearing skeleton. In addition, increasing NMAS delayed crack initiation, reduced crack propagation rate, and decreased the total number of cracks at failure. These findings demonstrate that macroscopic strength improvement is closely associated with meso-scale optimization of the aggregate skeleton and enhanced load-transfer efficiency. This study provides a mechanistic basis for NMAS selection and gradation optimization in semi-rigid base materials. Full article

Background/Objectives: A robust and scalable manufacturing framework for lipid-based nanocarriers remains a critical challenge, particularly for labile phytochemicals such as curcuminoids in turmeric. This study presents an integrated Quality by Design (QbD)-driven and Outcome-Based Design (ObD) strategy to establish a scalable, resource-efficient manufacturing process for curcuminoids-loaded nanostructured lipid carriers (NLCs). Methods: To overcome the limitations of conventional multivariate design of experiments (DOE), which require extensive experimental runs, a risk-based, knowledge-driven single-factor screening approach was employed. Guided by risk assessment tools, including Ishikawa diagrams and failure mode considerations, 12 representative processing conditions were selected to define the design space. Critical quality attributes (CQAs), namely, particle size, polydispersity index (PDI), and zeta potential, were predefined to establish a robust control strategy. A two-step homogenization process—high-shear homogenization (HSH) for pre-emulsification followed by high-pressure homogenization (HPH) for nanoscale refinement—was systematically optimized. Results: Multivariate data analysis using principal component analysis (PCA) and hierarchical cluster analysis (HCA) identified key critical process parameters (CPPs), particularly HSH speed, processing time, and HPH cycles, as dominant factors influencing nanoparticle characteristics. The optimized 1-h process enabled successful scale-up of NLCs from 100 g to 5000 g, demonstrating the capability to generate nanosized particles within 100–500 nm. The combined HSH–HPH approach produced smaller, more uniform nanoparticles with high encapsulation efficiency and physical stability, outperforming HSH alone. Conclusions: Overall, this study establishes a practical and industrially viable framework that integrates QbD principles with data-driven optimization tools, for enabling reliable translation from laboratories to semi-industrial production. Full article

The particle size of aggregate is a key factor affecting the mechanical properties and deformation capacity of cemented gangue filling body. In this study, coal gangue with a particle size range of (0.05, 20) mm was sieved into six groups of aggregate particles. Based on the Talbot gradation theory, cubic specimens with gradation indices n = 0.3, 0.4, 0.5, 0.6, and 0.7 were prepared for acoustic emission (AE) monitoring tests. The microstructure of the filling body was analyzed, and the failure characteristics and damage evolution laws of the cemented gangue filling body with different gradation indices were explored. The results show that the compressive strength reaches its maximum when n = 0.5. As the gradation index increases, the compressive strength of the specimens first increases and then decreases, and the specimens shift from primarily experiencing cleavage failure to shear failure. The curve of cumulative AE ringing count shows a bimodal distribution pattern, with both surge points and fracture points coexisting. The surge points can be regarded as precursor signals of backfill failure. The spatiotemporal evolution of AE events exhibits complex phased changes. An excessively small gradation index tends to form micropores and striped microcracks, reducing the compactness of the microstructure. An excessively large gradation index can lead to the formation of penetrative weak channels. A reasonable gradation index enables the mutual interlocking of aggregate particles, constructing a stable three-dimensional spatial skeleton structure. The dynamic trend of damage in the filling body can be captured based on AE analysis, and reverse guidance can be provided for parameter optimization of Talbot gradation, achieving a dynamic closed loop of “gradation design-AE monitoring-damage assessment-parameter optimization”. This not only enriches the application scenarios of acoustic emission analysis in graded materials, but also provides a new research approach and technical method for gradation design and safety assessment in scenarios where particle sizes are missing in practical engineering. Full article

The study aimed to develop a mucoadhesive thermosensitive buccal gel capable of forming an artificial clot after application in the extraction socket and providing prolonged release for metronidazole (MZ) and ibuprofen (IB). The critical quality attributes of the product were systematically evaluated using Ishikawa (cause–effect) diagrams as a risk assessment tool, considering the factors related to the formulation, process, and methodology. Subsequently, Failure Mode and Effects Analysis (FMEA) was used to identify the critical parameters of the formulation and process characterized by a high probability of occurrence and a significant impact on product performance. The influence of qualitative and quantitative formulation variables was further investigated using two experimental designs, applied for both screening and optimization purposes. The rheological, adhesion, and in vitro release properties of the drugs were studied, and the optimized formulation for these characteristics contains Poloxamer 407 20.99% and HPMC K100M:K4M 1:1, 0.74%. The release of MZ and IB was prolonged over 8 h and followed Peppas’s kinetics. The optimized formula had an appropriate pH and an acceptable ex vivo mucoadhesion time. Stability studies revealed the preservation of mechanical properties and a recovery coefficient for MZ and IB of over 90%, after 12 months of storage. The optimized formula may be a potential candidate for the prevention of alveolar osteitis. Full article

Acoustic emission (AE) and digital image correlation (DIC) techniques enable real-time capture of damage signals and full-field deformation at anchored rock–concrete interfaces under shear loading, which is critical for quantitatively characterizing freeze–thaw (F-T) degradation and preventing geological disasters in cold regions. This study synchronously monitored full-shear-process AE signals using a broadband AE system (150 kHz resonant frequency, 5 MS/s sampling) and captured high-precision full-field deformation via a 5-megapixel monocular DIC system (25 fps). F-T cycle and direct shear tests were conducted on sandstone–concrete anchored specimens with varying F-T cycles and anchor depths to investigate their effects on shear mechanical properties, AE characteristics and failure modes. Results show that AE peak ring count first decreases by 44.9% then increases by 56.5%, while cumulative ring count exhibits a three-stage evolution. Shear crack proportion first decreases then increases, with tensile failure remaining dominant throughout. DIC reveals that F-T cycles shift failure from crack propagation to surface delamination and interface slip, while different anchor depths induce distinct failure patterns. This study confirms that AE and DIC can accurately characterize F-T degradation, providing a reliable non-destructive monitoring method for cold-region anchorage engineering. Full article

In goafs formed by underground mineral resource extraction, the remaining pillars are often subjected to uniaxial loading at different loading rates, and their mechanical responses and failure mechanisms directly affect the long-term stability of the goafs. This study uses rock-like materials to conduct uniaxial compression tests at loading rates ranging from 0.001 mm/min to 0.05 mm/min, combined with acoustic emission (AE) monitoring, to systematically investigate the effects of loading rate on the mechanical properties, energy distribution, constitutive model, and AE characteristics of the material. The results show that an increase in loading rate significantly enhances the stiffness and strength of the material, promotes a transition in failure mode from a shear–tension composite to tension-dominated, intensifies brittle characteristics, and simultaneously inhibits full crack development and fragments generation. In terms of energy evolution, an increased loading rate enhances the pre-peak total strain energy and elastic strain energy storage but reduces the efficiency of energy dissipation, leading to an intensified mismatch between energy storage and dissipation capacities at peak stress. A damage variable induced by loading rate was proposed, and a damage constitutive model considering the loading rate was established, with the theoretical curves showing good agreement with the experimental data. AE characteristic analysis further reveals that an increase in loading rate causes the crack type to transition from shear-dominated to tension-dominated, and the fluctuating increase in the b-value reflects a reduction in pre-peak fracture scale and a decrease in the degree of material fragmentation. The research findings are expected to deepen the understanding of the damage and failure mechanisms of rock materials under different loading rates, thereby laying a research foundation for the stability assessment of goaf pillars and disaster warning. Full article

One of the most important design requirements for aircraft mechanical systems is to ensure that their motion functions can be executed smoothly. In this paper, an unconstrained reliability allocation method is proposed, taking into account the characteristics of aircraft mechanical systems. A decomposition principle for assessing the motion performance of aircraft mechanical systems has been proposed, and the contribution of each subsystem is analyzed. Weighting factors for system allocation are proposed and refined, and a failure correlation index is proposed to account for the influence of the interaction between subsystems on the potential failure rate. Furthermore, non-destructive failure events that could have a significant impact on motion performance have been taken into account in the potential improvement of subsystems. Subsequently, reliability prediction models of the systems are established using the Copula function, and a calculation method is introduced to distinguish and quantify the correlation between different subsystems. Finally, the applicability and validity of the proposed method are demonstrated through an engineering case. The results indicate that when failure correlation is considered, the reliability allocated to subsystems is significantly lower than that obtained using traditional methods, providing theoretical guidance for the reliability design of aircraft mechanical systems. Full article

This study investigated the post-fire resistances of 6063-T5 aluminium alloy angle section stub columns (SCs). The post-fire mechanical properties of 6063-T5 aluminium alloy were assessed using tensile coupon tests. Instead of exhibiting a yield plateau, the stress–strain curves indicated a shift from an elastic to a strain-hardening phase. The impacts of elevated-temperature exposure on the residual elastic modulus were negligible. Strength properties decreased while ductile properties increased within the elevated-temperature range of 200 to 450 °C, with a subsequent strength increase observed beyond 450 °C. After the SC tests, gradual decreases in ultimate resistance were observed within 200–450 °C, followed by an increase beyond 450–500 °C. These trends in the ultimate resistance closely paralleled those strength characteristics observed in the stress–strain curves. As regards the failure mode, all specimens experienced local buckling after exposure to the range of elevated temperatures. The failure mode, ultimate resistance, and load–end shortening curve were used to evaluate a numerical modelling approach that was created to simulate the residual resistance of SCs after exposure to different elevated temperatures was applied. The EC9, ADM-2020, AS/NZS 1664, and GB 50429-2007 were among the design approaches that were evaluated using the experimental and numerical data. Due to the increased strain-hardening behaviour caused by elevated temperatures, the existing design methods proved excessively conservative when applied to the direct prediction of ultimate resistances of 6063-T5 aluminium alloy angle section SCs. The modified design provisions in light of the observed post-fire strain-hardening behaviour improved the accuracy in predicting the residual bearing capacity of 6063-T5 aluminium alloy angle section SCs, which showed better agreement with test and numerical results, offering enhanced applicability for post-fire design. Full article