Search Results (1,507)

This paper extends the data-driven computational mechanics paradigm to nonlinear materials characterized by the Duncan–Chang Elastic-Bulk (E-B) constitutive model. Unlike in linear elastic systems, geotechnical media exhibit stress-dependent tangent moduli and non-convex constitutive manifolds. We propose a recursive nested data-driven solver that dynamically adapts the phase-space distance metric to account for pressure-dependent hardening. A rigorous mathematical analysis of convergence is provided, demonstrating that the solver’s performance is governed by the local transversality between the conservation law constraint set and the nonlinear material manifold. We derive explicit error bounds that couple spatial discretization resolution with material data density. Numerical experiments using triaxial test data from a high-altitude region validate the theoretical predictions, showing that the proposed scheme demonstrates convergence in single-element tests. Full article

With the evolution of new power systems, harmonic sources in distribution networks have become increasingly dispersed, thus requiring lower-cost harmonic mitigation devices suitable for large-scale deployment. With its simple control architecture, the one-cycle controlled active power filter (APF) is better adapted to meet the aforementioned requirements. That said, under non-ideal voltage conditions like voltage distortion or unbalance, the compensating target current of the APF that relies on traditional one-cycle control (OCC) will undergo distortion as well, resulting in a substantial reduction in the compensation effect. This paper introduces a modified OCC method based on a positive-sequence filter, which allows for the control of a reduced-switch three-phase APF. This control method eliminates the negative sequence and harmonic components in the target current of the APF, and makes the compensated current maintain a good sinusoidal waveform. A one-cycle control equation applied to the reduced-switch APF was derived. The modified one-cycle control method allows the active filter to retain a favorable compensation effect when operating under non-ideal voltage conditions. Meanwhile, it preserves the inherent advantages of traditional one-cycle control, including the elimination of a phase-locked loop (PLL), a fixed switching frequency, and a straightforward control structure. Finally, an APF simulation model and a dSPACE-based APF experimental circuit were built to verify the proposed control method. In simulation, with the adoption of the modified OCC, the THD of the current was reduced from 8.25% before improvement to 3.79% after improvement. In experiments, according to the spectrum analysis function of the oscilloscope, the third-order current harmonic caused by voltage distortion was decreased from 500 mA to 100 mA, representing a reduction of 80%. Both simulation and experimental results verify that the proposed modified one-cycle control method can effectively solve the problem that control performance is susceptible to voltage quality. Full article

The momentum transport and scale-dependent motion characteristics within vegetation canopies play a crucial role in shaping near-surface turbulent structures and exchange processes, yet the interactions among different turbulent scales and their statistical representations remain insufficiently understood. Based on a series of controlled wind tunnel experiments, this study identifies coherent turbulent structures using a phase-space algorithm constructed from streamwise velocity fluctuation u′, acceleration a, and jerk j, and compares transport efficiency (exuberance η). This study uses scale-wise (cut-off frequency) momentum flux contribution analysis, natural visibility graph (NVG), and large–small-scale amplitude modulation to examine transport and multiscale behaviors across different canopy densities, array layouts, and inflow conditions. Results show that canopy density (different C_d drag coefficient) is a primary factor governing transport efficiency. Under low-wind staggered configurations, increasing canopy density strengthens the contribution of low-frequency large-scale motions to total momentum flux. In contrast, high-wind aligned configurations intensify canopy-top shear, enhancing small-scale motions and thereby reducing the relative contribution of large-scale motions. NVG analysis further reveals that in high-density canopies, large-scale acceleration and deceleration events tend toward equilibrium, whereas deceleration events dominate consistently in low- and medium-density cases. Amplitude modulation results indicate that high-density cases exhibit highly consistent modulation behavior, followed by low-density cases, while medium-density cases display a pronounced height-dependent variation, characterized by a distinct modulation critical point. This study proposes a unified analytical framework integrating coherent structure detection, graph-theoretic analysis, multiscale transport characterization, and large–small-scale modulation, providing a comprehensive description of momentum transport and scale motions within canopy flows, and it offers new insight into the mechanisms governing complex vegetation canopy turbulence. Full article

Pawnshop buildings are places where pawn transactions are conducted. They are usually composed of a front shop and a back building, and their shape resembles a fortress. As a typical gambling city, pawnshops in Macau appeared as early as the Qing Dynasty. By the late Qing Dynasty (1644–1912) and early Republic of China (1912–1949), they had become a common market. They reached their peak during the Anti-Japanese War and were an important financial institution for the people to solve their urgent needs. Today, many pawnshop buildings have become architectural heritage sites and are distributed around the buffer zone of the World Heritage Site. Their location is consistent with the evolution of urban space and the development of gambling and tourism industries. However, existing research lacks systematic research based on spatial quantification technology and it has yet to be determined whether there is a spatial alignment relationship between pawnshop location and urban spatial structure. This paper takes the whole of Macau as the research area and combines DepthmapX space syntax, GIS analysis, and historical data comparison of pawnshop buildings to explore the path dependence characteristics of pawnshop building location and the service radius law in urban space. The study found that the location of pawnshop buildings in Macau has evolved through three stages: initially relying on traditional market spaces, then gathering around casino areas during a stable phase, and finally becoming closely tied to the core areas of gambling venues in the prosperous stage. It shows a path dependence that is continuously strengthened on nodes with low traffic resistance. The service radius of pawnshop buildings exhibits an unbalanced characteristic, with a dense core area and a blank peripheral area, forming a multi-level system of a 200 m core service circle, a 400 m extended service circle, and an 800 m radiation service circle. This study proposes pathways for the adaptive reuse and activation of traditional pawnbroking architectural heritage. For instance, by drawing on the operational model of the Tak Seng On Pawnshop, the integration of cultural exhibition and livelihood services can be realized, thereby providing practical references for the adaptive reuse and conservation of heritage assets. This study offers dual theoretical and practical support for the conservation of pawnbroking architectural heritage in Macau, the site selection and planning of modern pawnbroking establishments, and the optimization of the city’s urban spatial structure. Meanwhile, it enriches the research system on the spatial alignment between the peripheral financial industry and urban space. Full article

We perform a systematic analysis of the nuclear dependence of two-particle–two-hole meson-exchange current contributions to inclusive lepton-nucleus scattering within the relativistic mean-field framework. We present microscopic calculations of nuclear responses for a set of 17 nuclei, ranging from helium to uranium, using a model with different Fermi momenta for protons and neutrons. We propose a novel scaling prescription based on the two-particle phase space and key nuclear parameters. The resulting description is accurate over a wide range of nuclear targets, with typical deviations below 10%, and allows for a separate treatment of the different emission channels. In addition, a consistent benchmark against electron-scattering data is provided. The parametrization presented provides a practical framework for extending the responses to different nuclear targets in neutrino event generators. Full article

We present a comprehensive study of host galaxies of radio sources within the 1.35$R_{200}$ of the Coma cluster by combining deep $144\mathrm{MHz}$ observations from the LOFAR Two-Metre Sky Survey (LoTSS-DR2) with optical spectroscopy and photometry from DESI and SDSS. We identify 79 spectroscopically confirmed cluster members with reliable radio emission and classify them into compact, extended, and tailed subsamples according to their radio morphologies. By combining their radio and optical properties, we find compact radio sources are predominantly associated with massive, quiescent galaxies driven by $\mathrm{AGN}$ activity, while tailed sources are largely hosted by star-forming galaxies, tracing ongoing ram pressure stripping ($\mathrm{RPS}$). Using phase-space analysis and a projected infall time proxy ($d_R$), we find that extended sources are preferentially located in the cluster outskirts ($d_R>1$), while tailed sources are concentrated in the intermediate infall region ($0.4<d_R<1.0$), highlighting the influence of the dense intracluster medium. Full article

This paper highlights the findings of the emergency excavation carried out at Avenida Miguel de Cervantes No. 35 in Écija, conducted in two phases between 1999 and 2000 and in 2003. The investigation revealed a domus featuring valuable decorative elements, including pictorial wall paintings and two high-quality mosaics. Stylistic analysis of the wall decorations identified a scheme composed of wide and narrow panels, with a predominance of bright green in the central zone, along with traces of figurative representations. The evidence suggests a second construction phase in the latter half of the 2nd century AD, followed by renovations in the 3rd and 4th centuries. The use of green prevailing monochromy appears to be associated with high-status representational spaces. A total of six samples from the wall paintings and mortars were analysed. X-ray diffraction (XRPD) and X-ray fluorescence (XRF) were employed for a minimally destructive preliminary study of the mortars, while confocal microscopy was used to observe the sequence in which the pigments were applied, and Raman spectroscopy enabled the identification of the pigments, notably highlighting glauconite as the green pigment. Full article

As the electrification of the automotive industry accelerates, the importance of small-scale motors used in applications such as HVAC systems and water pumps is growing. To design small motors that exhibit high efficiency and high output within limited spaces, applying axial flux motors (AFMs) instead of conventional radial flux motors (RFMs) can maximize the power density within the same volume, offering advantages in both weight reduction and miniaturization. This study proposes an optimized end-turn layout design to mitigate back-EMF imbalance in AFMs utilizing PCB stators. Optimization results demonstrated that the structure employing a non-adjacent end-turn layout with equalized average end-turn heights (BCAACB type) exhibited the best performance in terms of average resistance and phase resistance variance, effectively mitigating back-EMF imbalance. The validity of the optimized end-turn structure was verified through finite element analysis (FEA). The analysis confirmed that the motor’s back-EMF balance was improved, and the magnitude of phase resistance was reduced. This reduction led to lower copper loss, thereby increasing overall efficiency. Furthermore, the variance in resistance for each phase was minimized, resulting in enhanced electrical balance. The results of this study are expected to contribute to enhancing the applicability of PCB stators in small motor design. Full article

Identity-based communities that share common characteristics, beliefs, and experiences (e.g., Black LGBTQ+ communities) have historically been conceptualized as protective bubbles that buffer Black LGBTQ+ individuals against the deleterious effects of systemic racism and cisheterosexism. However, this monolithic narrative often masks the internal power dynamics that divide belonging. This study explores the exclusionary dynamics embedded within these safe spaces, examining how internal hierarchies of skin tone, socioeconomic status, and gender performance function as proximal stressors. Guided by a critical constructivist paradigm, this study utilized Reflexive Thematic Analysis to analyze open-ended survey responses from 74 Black LGBTQ+ adults. Data were drawn from a larger mixed-methods study and analyzed using a six-phase recursive process to identify latent patterns of intragroup gatekeeping. The analysis revealed that the sanctuary of the community is restricted. Three primary themes emerged: (1) Phenotypic Capital and the Politics of Authenticity, where lighter skin tone triggered authenticity scrutiny and darker skin tone faced rejection based on physical appearance; (2) Socioeconomic Gatekeeping, where belonging was stratified by the cost of participation and protective insularity within working-class spaces; and (3) Policing the Binary, where rigid adherence to gender archetypes created a landscape of performance surveillance. Access to community resilience is not a universal right but a negotiated status contingent upon the payment of a resilience tax. To promote genuine health equity, researchers and practitioners working with this population must move beyond the uncritical referral to “community” and actively dismantle the internalized systems of oppression that fracture collective survival. Full article

Cropland dynamics in ecologically fragile regions are central to balancing food security and ecological integrity in the Yellow River Basin. Ningxia Hui Autonomous Region is used as a case study. An integrated simulation framework is developed by coupling an improved grey prediction model (Improved GM(1,1)) with the CLUMondo spatial model. The analysis addresses four questions: how cropland changed during 2009–2024, which drivers explain cropland suitability and transitions, what spatial resolution is appropriate for implementation, and how cropland patterns differ under alternative development pathways for 2025–2040. Historical cropland change in Ningxia during 2009–2024 is quantified, and spatial patterns for 2025–2040 are projected under three scenarios: business-as-usual (BAU), ecological protection (EP), and rapid urbanization (URE). Cropland change during 2009–2024 shows pronounced phased fluctuations and a stable redistribution pattern described as “southern reduction and northern replenishment, urban decrease and rural increase”. Population growth, economic expansion, and policy regulation jointly drive this spatiotemporal reconfiguration. Land demand forecasting is improved by introducing a metabolism mechanism and residual correction into the grey model, which reduces mid- to long-term divergence. Multi-scale logistic regression tests show the highest AUC at 50 m, with AUC values exceeding 0.8 across land categories, and this resolution is used for model implementation. Model performance is evaluated using AUC, Kappa, and overall accuracy, supporting the applicability of the framework in arid, ecologically fragile regions. Scenario simulations reveal clear divergence in future spatial outcomes. BAU maintains sustained pressure on cropland protection and ecological security. URE increases the risk of encroachment on high-quality cropland in the central–northern irrigated areas due to urban expansion. EP constrains construction land growth and secures strategic ecological spaces, thereby slowing the loss of high-quality cropland while maintaining development capacity. These results provide a transparent basis for scenario-based territorial spatial planning in Ningxia and offer transferable evidence for managing cropland–ecology tradeoffs in arid and semi-arid regions. Full article

Peripheral nerve regeneration is most rapid during the early post-injury period but gradually slows over time, often limiting functional recovery. Electrical stimulation (ES) delivered via percutaneous needle electrodes has been shown to modulate the local neural microenvironment and promote axonal regeneration; however, the optimal temporal window and duration of stimulation remain unclear. This study aimed to evaluate the time-dependent effects of needle-based ES on peripheral nerve regeneration in a rat model of sciatic nerve transection, using a well-established silicone nerve conduit as a stable and reproducible non-biodegradable repair model. Female Sprague–Dawley rats underwent sciatic nerve transection and repair. Postoperatively (PO), animals were randomly assigned to control (C) needle insertion or needle-based ES groups, receiving stimulation for either 3 weeks (C-3W-PO and ES-3W-PO, respectively) or 7 weeks (C-7W-PO and ES-7W-PO, respectively). Functional recovery was evaluated using cold plate latency and rotarod performance tests. Electrophysiological assessments included measurements of nerve conduction velocity (NCV), compound muscle action potential amplitude, and muscle action potential (MAP) area. Histomorphometric analysis of regenerated nerve tissue quantified total nerve cross-sectional area, endoneurial space, axon number, and axon density. Retrograde labeling with fluoro-gold (FG) was used to quantify reinnervated motor neurons. Immunohistochemical analyses of calcitonin gene-related peptide (CGRP) and macrophage-associated markers were conducted to assess sensory neuropeptide expression and immune cell infiltration within the regenerated nerve. ES significantly improved both sensory and motor recovery in a duration-dependent manner. Behavioral data showed increased cold pain thresholds and improved motor coordination in ES groups, with the most pronounced functional gains observed in the ES-7W-PO group. Electrophysiological measures revealed higher NCV, amplitude, and MAP area in ES-treated animals, with the most pronounced improvements at 7 weeks. Morphologically, ES enhanced nerve regeneration, as evidenced by increased total and endoneurial areas, axonal counts, and axon density. FG-labeled neuron counts were significantly elevated in ES groups, indicating enhanced motor reinnervation. At 3 weeks, ES induced higher CGRP expression and macrophage density, suggesting transient activation of sensory-associated and pro-regenerative immune responses during the early post-injury phase. These findings demonstrate that ES accelerates peripheral nerve repair in rats and that sustained stimulation across the early regenerative window yields superior structural and functional outcomes. Full article

The integration of renewable energy sources, including photovoltaic (PV) and fuel cell (FC) systems, into AC grids has attracted immense research interest in recent times. Furthermore, incorporating these renewable sources of energy into medium-voltage grids is garnering increased attention because of the obvious benefits of medium-voltage integration at elevated power levels. Photovoltaic applications entail the arrangement of solar panels capable of outputting voltages up to 1.5 kV; nonetheless, fuel cells display restricted output voltage, with a maximum market range of 400 to 700 V. Hence, the efficient integration of renewable energy sources into low-voltage or medium-voltage grids demands the utilization of a step-up direct current (DC–DC) inverter and a converter for connection to the alternating current (AC) grid, in which an efficient step-up converter is critical for the medium-voltage grid. Therefore, this study presents a three-phase buck-boost split-source inverter (BSSI) that resolves the constrained output voltage of the fuel cells. This study focuses on modifying the configuration of a conventional three-phase split-source inverter (SSI) circuit by adding a few components while maintaining the inverter’s modulation. This novel circuit design enables the reduction in voltage strains on the inverter switch components and improves DC-link use in relation to a traditional SSI configuration. For an 800 bus, maximal voltage stress on the primary inverter switches is lowered when compared with the standard SSI that delivers entire DC-bus voltage to switches. A rectifier-based model is employed to simulate the behavior of a renewable energy source. Combining these advantages with the conventional modulation of the inverter offers a more effective design. The buck-boost split-source inverter (BSSI) was analyzed using three distinct modulation techniques: the sinusoidal pulse-width modulation scheme (SPWM), the third-harmonic injected pulse-width modulation (THPWM) scheme, and space vector modulation (SVM). The proposed analysis was validated through MATLAB-SIMULINK and practical outcomes on a 5.0 kW model. The practical and SIMULINK data were found to be closely aligned with the analysis. The circuit developed in this study also ensures efficient DC-to-AC conversion, specifically with regard to low-voltage sources, like fuel cells or photovoltaic (PV) systems. Full article

Reported are the synthesis and detailed analysis of the crystal and electronic structure of the novel Zintl phase Eu₉Zn_4.5As₉. This material was identified in the densely populated Eu–Zn–As compositional space. For structure determination and for property measurements, suitable single crystals of this compound were grown from either Sn- or Pb-flux. Single-crystal X-ray diffraction methods indicate that Eu₉Zn_4.5As₉ crystallizes in the orthorhombic crystal system with the space group Pnma (a = 12.1953(7) Å, b = 4.3730(2) Å, c = 42.674(2) Å) and is formally isostructural to Ca₉Mn_4+xSb₉, the less common “9–4–9” type. The structure is heavily disordered, with multiple partially occupied sites, yet, according to the Zintl-Klemm formalism, a charge-balanced composition (Eu²⁺)₉(Zn²⁺)_4.5(As³⁻)₉ is attained. Electronic structure calculations for a model, disorder-free structure indicate no energy gap between the valence and the conduction bands and suggest (semi)metallic behavior. Preliminary susceptibility measurements confirm the expected divalent nature of Eu²⁺ ([Xe] 4f⁷ ground state). Full article

This paper presents a detailed investigation of the deterministic and stochastic dynamics of a noise-driven forced nonlinear oscillator in a periodically driven framework. An overlap-mapping approach is used to compare multiple traveling-wave solutions and verify the structural consistency among distinct solution families. The qualitative behavior of the system is further characterized through geometric and stability-based analysis, supported by two- and three-dimensional phase portraits, time-series responses, and reconstructed three-dimensional attractors to examine periodic and chaotic regimes under varying parameters and initial conditions. The sensitivity to parameter perturbations is quantified and the distribution of final states is analyzed to identify chaotic regions in the phase space. The high-dimensional chaotic nature of the dynamics is rigorously confirmed through Lyapunov exponent estimation, Poincaré sections, and return-map analysis, collectively demonstrating strong sensitivity to initial conditions and systematic transitions induced by parameter variations. These results provide a comprehensive dynamical description of the nonlinear oscillator and contribute to a deeper understanding of noise-influenced nonlinear driven systems. Full article

This study investigates the temporal and latitudinal variability of the ionosphere over the Indian longitude region during the intense geomagnetic storm from 1 to 3 June 2025, using GNSS receiver observations and magnetometer recordings, along with space-based measurements from in situ Swarm satellite, COSMIC-2 radio occultation, GUVI/TIMED-derived O/N₂ ratios, and model-derived electric fields. This particular event is relatively new and is characterized by the bifurcated variation with two distinct main phases separated by a short-lived recovery phase. The results revealed distinct features associated with the geomagnetic storm, including positive and negative ionospheric phases, thermospheric compositional changes, and the latitudinal propagation of disturbances. On 1 June, the observed strong positive ionospheric storm was driven by Prompt Penetration Electric Fields (PPEFs) and equatorward neutral winds, which triggered the upliftment of F-region plasma to higher altitudes through the enhanced equatorial fountain effect, leading to an unusually long-lasting Total Electron Content (TEC) enhancement from day to night. The analysis also revealed the distinct latitudinal behaviour, exhibiting the clear poleward extension of the Equatorial Ionization Anomaly (EIA) crest and significant TEC enhancements (~150–200% of the quiet day values) from low to mid latitudes as compared to the equatorial location through an efficient plasma redistribution. Conversely, pronounced negative ionospheric storm effect at almost all latitudinal locations on 2 June confirms complex and unusual storm-time dynamics, with inhibited upward plasma drifts due to the presence of Disturbance Dynamo Electric Fields (DDEFs), while the thermospheric O/N₂ ratio caused an extensive decrease in electron density over the Indian region. Minor negative storm noticed on 3 June coincides with the storm recovery period, reflecting prolonged disturbance dynamo effects and gradual recovery in thermospheric conditions. Overall, the current study highlights the strong sensitivity of the regional ionosphere to prevailing coupled electrodynamic-thermospheric forcing during the June 2025 geomagnetic storm that has not yet been reported for this event over the Indian longitude sector. Moreover, the findings from this study underscore peculiar storm-time behaviour of summer solstice ionosphere over the Indian longitude sector, driven by complex coupled processes which could be incorporated into ionospheric models and forecasting frameworks. Full article