Search Results (17,620)

Land-intensive high-density residential development often comes at the cost of compromised natural ventilation efficiency and reduced capacity for urban heat island mitigation, and such trade-offs are particularly pronounced in valley cities due to topographical constraints. Taking Lanzhou Yineng Huanghe Jiayuan as a case study, this research constructs a “Source-Flow-Sink” landscape ventilation efficiency measurement framework based on circuit theory and CFD numerical simulation. Combined with correlation analysis and multiple linear regression, the coupling mechanism between spatial morphology and ventilation efficiency is examined. The results indicate that: (1) The study area exhibits a ventilation pattern characterized by “Source” in the north, “Flow” in the middle, and “Sink” in the south; (2) The wind speed ratio in the residential area shows a highly significant negative correlation with vegetation coverage, and a significant negative correlation with building dispersion and average building height; (3) Based on three configuration modes of “Source-Flow-Sink”, differentiated micro-renewal strategies that do not alter the core indicators of land intensification are proposed, providing a scientific basis for climate-adaptive design of intensive residential areas in valley cities. Full article

Variable-speed pumped storage units perform flexible and rapid regulation tasks in power grids. However, under the “power-priority” control mode, the superposition of maximum energy operating point and extreme transient events such as load rejection can induce severe vibrations. This study investigates the vibration characteristics of a variable-speed unit under a typical extreme condition (Case RT-5): power-priority mode, maximum energy superposition point, and load rejection at extreme rotational speed. A one-way fluid–structure interaction (FSI) numerical method is employed, combining unsteady Reynolds-averaged Navier–Stokes (URANS) with a shear stress transport (SST) k-ω turbulence model and finite element structural analysis. The innovation lies in quantitatively linking the transient hydraulic excitation (water hammer pressure waves, non-stationary pulsation field) to the mechanical response (centrifugal force, variable stiffness) to identify the root causes of vibration. Results show that under RT-5, the maximum equivalent stress reaches 97.09 MPa and maximum deformation 0.66 mm, occurring at the blade-crown connection root—a stress concentration zone. However, below the material yield strength (265 MPa), the stress rises 2.4-fold within 12 s, and secondary stress peaks appear, indicating high-cycle fatigue risk. Severe fluctuations of stress and displacement, driven by coupled hydraulic-mechanical excitation, are the main causes of vibration. This study provides a theoretical basis for safety assessment and control strategy optimization, and proposes that RT-5 be included as a mandatory verification case for variable-speed units. Full article

Grid-connected photovoltaic–battery energy storage–electric vehicle (PV-BESS-EV) charging stations require supervisory energy management that can coordinate tariff response, carbon-intensity signals, peak constraints, storage utilization, and converter-level operability within a transparent evidential framework. This study develops a bounded-reference rule-based supervisory energy management system (RB-SEMS) that preserves lower-level local converter controllers while generating operating modes and saturated reference commands for BESS power, grid exchange, and EV charging limits. A dual-time-scale evaluation framework is established by combining short-time switching/control simulations for dynamic traceability and SOC-sensitive protection with 24 h, 15 min EMS-level energy-balance simulations for cost, carbon, peak, PV utilization, EV service, and storage throughput assessment. Selected daily reference-injection cases are retained as copied-model diagnostic checks rather than as full-day switching-level validation. Under the D4-LSOC condition, RB-SEMS reduces the reported post-startup DC-bus deviation from 46.13 V to 40.60 V and the filtered BESS peak from 269.18 kW to 84.42 kW. In the E1-TOU scenario, E1-TOU-cost reduces daily total cost from 623.57 CNY to 564.05 CNY, lowers peak-period grid import from 183.75 kWh to 126.75 kWh, and increases local PV utilization from 71.13% to 78.71%; E1-PC66 further reduces the maximum 15 min grid import from 77.88 kW to 66.00 kW. Under the prescribed E2-PCC scenario, E2-CP reduces the calculated grid-related CO₂ emissions from 550.29 kg to 500.42 kg, whereas the price-only diagnostic increases them to 572.29 kg. Same-metric PV-SC and MILP comparisons, tested-range sensitivity analysis, and a throughput-based degradation proxy clarify that RB-SEMS is an interpretable supervisory baseline for cost–carbon–peak–cycling trade-off analysis rather than a cost-optimal controller or regionally validated proof of carbon reduction. Full article

This paper presents an AI-assisted design of a tunable narrow-linewidth external cavity laser based on an asymmetric Bezier cascaded triple-ring resonator. To address the high bending loss, limited quality factor, and footprint–loss trade-off in conventional external cavity ring resonators, asymmetric Bezier waveguide bends are introduced and optimized using particle swarm optimization, enabling smoother mode evolution and reducing bend loss. On this basis, this paper constructs a triple-ring-coupled external cavity structure to further enhance the mode-selection capability and filtering performance of the resonant cavity. Simulation results indicate that the asymmetric Bezier resonator optimized using particle swarm optimization can effectively reduce cavity loss and improve the resonator quality factor while maintaining a compact device footprint. Theoretical analysis indicates that the designed laser based on the proposed external cavity can achieve a linewidth of approximately 390 Hz. This work provides a feasible approach for designing high-performance, low-loss, and narrow-linewidth-integrated lasers, and is of significance for the development of integrated photonic laser sources. Full article

Economic dispatch in grid-connected microgrids is challenged by the variability of renewable generation, the uncertainty of demand, and the need to simultaneously satisfy technical and economic constraints under different operating conditions. This study proposes an integrated predictive economic dispatch strategy for power grids with interconnected microgrids, structured as a unified optimization framework. The approach integrates nodal electrical modeling, Optimal Power Flow (OPF)-based optimization, multi-scenario analysis, and post-optimization feasibility verification based on performance indicators within a single decision-support structure. The methodology is applied to a modified 14-node power grid interconnected with a microgrid, where simulations are conducted under three representative load scenarios (100%, 70%, and 40%) and two operational configurations (hybrid and renewable-only), enabling a comprehensive assessment of system behavior. Results show that the hybrid configuration consistently outperforms the renewable-only case, achieving loss reductions of up to 7.3 MW, increases in spinning reserve exceeding 50 MW, and a transition from net power import to export of approximately 50 MW under high demand. Additionally, the microgrid plays an active operational role, dynamically switching between import and export modes based on load levels and the generation mix. The proposed framework enables identification of operationally efficient and technically feasible configurations by incorporating bidirectional power exchange, electrical constraints, and reserve requirements. The main contribution lies in integrating technical, operational, and interaction variables within a single deterministic Optimal Power Flow (OPF)-based assessment scheme to support decision-making in interconnected microgrid-based power grids. Full article

The Yellow River Delta is a representative coastal saline–alkaline ecosystem in China, where high salinity and complex soil properties create a distinct habitat that significantly shapes microbial community structure and function. In this study, we analyzed 34 saline–alkaline soil samples from four regions within the delta. We characterized soil physicochemical properties (salt content, electrical conductivity, and pH) and systematically assessed fungal diversity, potential ecological functions, and their relationships with environmental variables using both internal transcribed spacer high-throughput sequencing and culture-based isolation. Sequencing generated 1,137,196 sequences that clustered into 13,574 operational taxonomic units (OTUs), with Good’s coverage values ranging from 0.96 to 1.00, indicating sufficient sequencing depth. The soils were generally alkaline and exhibited pronounced spatial heterogeneity in salinity and electrical conductivity. Sequencing analyses revealed Ascomycota and Basidiomycota as the dominant fungal phyla. Alpha diversity tended to decline with increasing salt content and electrical conductivity; however, substantial within-group variability indicated strong microenvironmental influences. Beta diversity analyses revealed distinct clustering patterns in community structure among regions based on PCoA ordinations. Redundancy analysis revealed that soil pH had the only significant unique contribution to fungal community variation. However, all three measured edaphic factors together explained only 17% of the total community variation. Functional inference using the FUNGuild database identified diverse fungal trophic modes and several plant-associated taxa in several samples. Culture-based approaches yielded 347 isolates representing 52 genera. Among the isolates, the vast majority (>95%) belonged to Ascomycota, with Basidiomycota represented by only a few isolates, which is consistent with the dominance of Ascomycota observed in the high-throughput sequencing data. Comparisons between sequencing and cultivation results demonstrated complementary diversity profiles and highlighted a substantial reservoir of nonculturable fungi in these soils. Overall, this study clarifies spatial patterns and key environmental drivers of fungal diversity in the Yellow River Delta and establishes a foundational culture collection for future ecological restoration efforts. Full article

Seismic retrofitting is widely used to enhance the dynamic performance of steel structures. This study experimentally investigates the effect of seismic damper retrofitting on a scaled steel frame using ambient vibration testing. Both as-built and retrofitted configurations were evaluated under low-amplitude excitations generated on a shake table. Modal parameters, including natural frequencies, mode shapes, and damping ratios, were identified using output-only Operational Modal Analysis (OMA) based on the Enhanced Frequency Domain Decomposition (EFDD) method. The results show a significant increase in damping ratios, with more than a 23-fold improvement in the first mode, along with mode-dependent frequency variations ranging from 17.63% to 142.74%. Mode shape comparison confirms strong consistency between configurations. The findings indicate that the integration of the damping devices enhanced the overall energy dissipation capacity of the scaled steel frame by increasing its global damping ratios and modifying the modal responses. The results suggest that output-only OMA can provide valuable insights into damper effectiveness, offering a practical alternative when controlled input excitation is not available. Full article

Objective: This study aims to explore the differences in chemical composition among Tibetan medicinal Rhododendron species and their potential correlation with anti-complement activity, with the goal of identifying promising medicinal resources. In Tibetan medicinal practice, the two groups of large-leaved Rhododendron (Tibetan: Dama) and small-leaved Rhododendron (Tibetan: Tali) are often used interchangeably despite unclear chemical and taxonomic bases. By comparing chemical profiles and evaluating anti-complement effects, this investigation seeks to provide preliminary scientific evidence for clarifying medicinal origins and facilitating the targeted development of high-quality resources. Methods: Ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS) was employed to analyze seven Rhododendron samples. Separation was achieved on a Waters CORTECS UPLC C18 column (2.1 × 100 mm, 1.6 μm) using a gradient mobile phase system consisting of acetonitrile and 0.1% formic acid in water, at a flow rate of 0.3 mL/min and a column temperature of 30 °C. Data were acquired in both positive and negative electrospray ionization (ESI) modes. Compound identification was performed using Peakview 1.2 software by comparison with databases and literature. Grey relational analysis and partial least squares (PLS) regression, combined with 5000 bootstrap resampling iterations, were applied to establish spectrum–effect relationships and to screen for characteristic peaks potentially associated with anti-complement activity. Results: A total of 52 compounds were tentatively identified, including flavonoids (e.g., hyperin, isoquercitrin, taxifolin-3-O-arabinoside), terpenoids (e.g., grayanotoxin I/III), and chromanes (e.g., anthopogochromane series). The CH₅₀ values of the ethanol extracts ranged from 179.29 to 579.47 μg/mL, with Rhododendron principis showing the strongest activity (179.29 ± 11.86 μg/mL), followed by Rhododendron vellereum (198.61 ± 7.93 μg/mL). Spectrum–effect analysis revealed that four unidentified peaks (F5315, F5822, F5368, F5991) exhibited negative regression coefficients and VIP means close to or above 0.8, suggesting a possible positive correlation with anti-complement activity. Among these, F5315 (VIP = 0.909), F5822 (VIP = 0.877), and F5368 (VIP = 0.834) showed relatively higher values and were considered preliminary candidate peaks warranting further investigation. Conclusions: This study tentatively identifies 52 compounds from the ethanol extracts of seven Tibetan medicinal Rhododendron species and reports their anti-complement activities. The findings reveal chemical distinctions between the large-leaved (Dama) and small-leaved (Tali) groups, offering a potential chemical basis for species differentiation and quality evaluation. Furthermore, four unknown peaks were preliminarily screened through spectrum–effect analysis as potential anti-complement candidates, which may serve as a foundation for future activity-guided isolation and quality marker studies. Full article

Piles with continuous helix (referred to herein as “screw pile”) is a new configuration of helical piles. It features a continuous helix spiraling several pitches around a smooth shaft forming a “threaded shaft”. This study investigates the compressive capacity and behavior of helical and screw piles using 3D numerical models calibrated and validated against full-scale field testing. The bearing capacity factor, $N_c$, for helical piles is back-calculated from the numerical results and compared against standard theoretical assumptions to evaluate their accuracy in predicting ultimate capacity. Parametric studies are conducted considering screw piles configuration, including shaft diameter, pitch size, helix diameter, as well as soil strength. The results reveal that shaft resistance accounts for up to 89% of the total capacity. Analysis of load distribution, shear contours, and displacement contours at failure allowed for the identification of different failure modes of soil adjacent to the pile’s threaded shaft: Individual Bearing Mode (IBM), Cylindrical Shear Mode (CSM), and a combined mode. The study identifies specific parametric thresholds for these modes in both sand and clay layers. Furthermore, varying clay strength is found to alter the development of the shear surface, transitioning from localized bearing to continuous shearing along the threaded shaft. Finally, apparent shaft resistance factors, $\alpha$ and $\beta$, are back-calculated to provide practical parameters for evaluating the resistance of threaded shafts in layered soil. Full article

During a severe earthquake, the violent shaking causes freestanding non-structural elements to sway and overturn, potentially injuring occupants or causing the elements themselves to break apart. This study investigates how freestanding contents (FSCs) in buildings respond to various earthquake intensities, detailing their movement through extensive analysis of dynamic performance. The stability of the FSCs on each floor varies depending on the earthquake’s intensity, the building’s structural mode shape, the FSCs’ geometry, and the chosen performance assessment method. A series of multi-level seismic excitation assessments of FSCs were conducted using 30 earthquake records, classified into 50%, 10%, and 2% probabilities of exceedance in 50 years. The floor’s responses, including absolute peak floor acceleration and relative peak floor velocity from both elastic and inelastic analyses, provided the seismic demand. The Ishiyama criterion made it difficult to evaluate FSCs’ seismic capacity because of the ambiguous distinction between rocking and overturning movements. A new criterion, specifically developed to differentiate between rocking and overturning of FSCs, has been proposed to address this issue. The results translate into practical guidance for design and protection: because the demand-to-capacity ratios for overturning are governed by the floor level, content slenderness, and the elastic-versus-inelastic modeling assumption, the proposed criterion identifies which floors and which content geometries are genuinely at risk, allowing anchorage, restraint, or relocation measures to be targeted where they are most needed rather than applied uniformly. This supports more reliable and economical seismic protection of non-structural building contents. Full article

Maintaining precise liquid levels in interconnected tank systems is a critical requirement in many industrial processes; however, achieving reliable control remains challenging due to inherent nonlinearities and external disturbances. This paper presents a comparative analysis of three control strategies—sliding mode control (SMC), feedback linearization (FL), and proportional–integral–derivative (PID) control—applied to a nonlinear two-tank system. To address the practical limitation of unmeasured system states, a high-gain observer (HGO) is integrated into the control architecture to reconstruct unmeasured water levels. In addition, the controller and observer parameters are optimized using a hybrid genetic algorithm to balance tracking precision and control effort. Simulation results demonstrate that, although all three methods achieve acceptable setpoint tracking performance, the SMC-HGO configuration exhibits superior robustness. Specifically, it outperforms FL and PID in rejecting external disturbances and maintaining stability under significant parameter variations, such as changes in discharge coefficients. Full article

This article presents a structured spectral-stability assessment of an nJ-class ultrafast fiber laser generating femtosecond pulses with an approximate pulse duration of 115 fs, based on an ensemble of 61 consecutively acquired optical spectra. The study is motivated by the practical need to extract reliable short-sequence stability information from routine compact-spectrometer exports without requiring a separate pulse-diagnostic instrument at the initial assessment stage. For each spectrum, peak wavelength, centroid wavelength, FWHM bandwidth, integrated spectral area, correlation with the ensemble mean spectrum, and RMS deviation were calculated. Principal component analysis (PCA) was then applied to reduce the full spectral ensemble into a compact diagnostic space and to identify the dominant modes of residual spectral variation. The analyzed spectra yielded a peak wavelength of 775.31 ± 0.19 nm, a FWHM bandwidth of 7.95 ± 0.20 nm, an integrated spectral area of 10.43 ± 0.42 a.u.·nm, and a correlation with the mean spectrum of 0.99957 ± 0.00019, confirming a highly repeatable spectral envelope. PCA showed that PC1 and PC2 explained 66.50% and 12.60% of the variance, respectively, while PC3 contributed only 1.90%, indicating that the measured variability was weak and largely low-dimensional. These results demonstrate that consecutively exported optical spectra can provide a defensible and physically interpretable short-sequence stability assessment of ultrafast femtosecond fiber lasers, offering a practical route for routine monitoring, early-stage diagnostics, and future integration with simultaneous temporal and spectral characterization. Full article

Tularemia is a zoonotic disease caused by the highly contagious bacterium Francisella tularensis, with rabbits, hares, and rodents considered as primary reservoirs. Clinical manifestations in humans can range from mild to life-threatening, depending on the mode of exposure (ingestion, inhalation, skin contact, injection, or tick bite), with high fever being a common feature. The primary aim of the present research was to evaluate the circulation of F. tularensis and the potential infection among wild boar (Sus scrofa) and red deer (Cervus elaphus) from the central region of Portugal. A total of 368 samples (including serum and organ samples) were collected from 184 wild boar and 184 red deer. For serological analysis, two commercially available enzyme-linked immunosorbent assay (ELISA) kits were used to detect immunoglobulin M (IgM) and G (IgG) antibodies to F. tularensis. Antibodies to F. tularensis (IgG and IgM) were detected in one adult male wild boar, corresponding to a seroprevalence of 0.54% (1/184, 95% confidence interval [95% CI]: 0.01–3.0%). No antibodies to F. tularensis were detected in red deer. Molecular detection by PCR was negative in the seropositive animal, in which submandibular lymph node, liver, and spleen samples were analysed targeting the 16S rRNA gene. These findings indicate exposure of wild boar to F. tularensis in central Portugal, suggesting a sporadic presence of the pathogen. Although no evidence of active infection was detected in the analysed tissues, the presence of seropositive individuals highlights the need for further investigation. Despite the very low seroprevalence observed, the zoonotic potential of F. tularensis supports the importance of continued surveillance within a One Health perspective. Full article

Large language models and vision–language models already achieve strong results on reasoning tasks, but their reliability under controlled assessment-style conditions remains insufficiently characterized. This paper presents a benchmark study of multimodal multiple-choice mathematical reasoning using 324 Austrian Mathematical Kangaroo competition problems (2022–2024), including both text-only and diagram-dependent items. We evaluate five state-of-the-art models under a controlled protocol that isolates two factors: input modality and prompt format. We compare a strict short-answer condition requiring a single option label (one_liner) with a structured condition eliciting step-by-step reasoning and an explicit final answer (full) while enforcing deterministic decoding and rule-based answer extraction. Performance is assessed using accuracy, abstention rates, and contest-style scoring, supported by paired and unpaired statistical analyses and a structured error taxonomy. The results show that prompt format is the primary driver of performance: structured prompting yields substantial gains across all the models, particularly on text-only items. In contrast, visual-text problems remain consistently harder, with a robust performance gap that persists across prompting conditions, indicating persistent limitations in visual grounding. Model comparisons are additionally influenced by response strategies, especially abstention behavior under strict output constraints. An error analysis reveals systematic failure modes, including constraint violations, inappropriate strategy selection, and diagram misinterpretation, alongside structured biases in multiple-choice selection under constrained prompting. Overall, the findings demonstrate that measured performance is highly sensitive to the interaction between prompt format and input modality. This underscores the importance of treating prompting, decoding, and answer extraction as integral components of evaluation in assessment-oriented settings, where reliability and reproducibility are central. Full article

The cosmic microwave background (CMB) contains key information about the early Universe, particularly through its polarization structure. This work proposes a Fuzzy and Explainable Artificial Intelligence framework (FAS-XAI) for the regional analysis of CMB polarization using Planck SMICA data. From the Stokes components Q and U, the polarization amplitude P and the scalar polarization modes E and B are derived. Regional features are then extracted over a HEALPix grid, considering only polarization-valid regions defined by the Planck polarization mask. Fuzzy C-Means identifies four interpretable polarization regimes: high-polarization structured regions, E-dominated medium-polarization regions, B-enhanced medium-polarization regions, and low-polarization regions. An XGBoost-SHAP layer is used to explain the resulting fuzzy memberships. XGBoost accurately reproduces the memberships, with R² > 0.98 for all clusters, while SHAP confirms the physical relevance of amplitude-related features and the log(B/E) balance. Finally, controlled perturbations in P and log(B/E) reveal a globally robust fuzzy structure with localized sensitivity. The proposed framework provides an interpretable methodology for studying regional CMB polarization patterns and their stability under controlled perturbations. Full article