Search Results (724)

Interior permanent-magnet synchronous motor (IPMSM) current-reference laws are commonly derived for one objective or operating region at a time. This study develops a safeguarded scalar framework that separates exact torque-equality elimination, current/voltage feasibility, torque-command derating, and performance-index selection. On the positive-motoring branch, the torque equality reduces the two-current problem to one variable, while convex current and voltage residuals define a connected feasible interval. Taylor-based quadratic boundary estimates are refined by fixed-count Newton steps and accepted only after residual, slope, and interval checks; failed candidates are routed to a deterministic convex-sublevel fallback. For a strictly convex reduced objective, safeguarded Newton proposals are followed by mandatory derivative-bisection contractions, which provide an explicit final-bracket error bound. Maximum-torque-per-ampere, fixed-torque voltage minimization, loss-oriented indices, a normalized current–voltage stress index, and two structurally convex design extensions are treated in the same pipeline. A 3844-point steady-state numerical sweep over two published IPMSM parameter sets and both zero-resistance and full-resistance voltage models contained 3071 feasible cases. The low-cost setting produced a maximum d-axis current error of $1.331\times {10}^{-3}$ A, whereas the conservative setting reduced it to $2.892\times {10}^{-4}$ A. The evidence is numerical and steady-state; processor timing and hardware validation remain future work. Full article

Bursting oscillations, characterized by alternating quiescent and spiking states, are a fundamental class of nonlinear dynamics that play a crucial role in diverse scientific fields. Therefore, understanding the mechanisms that generate bursting is of both theoretical and practical importance. Bursting is typically studied as a class of self-excited or forced oscillations in classical slow–fast dynamics, with analysis relying on stable invariant sets and their bifurcations. In contrast to these cases, we extend the analysis to hidden bursting in a 4D slow–fast system with no equilibria using classical slow–fast decomposition. Specifically, we show how chaotic saddle dynamics in the fast subsystem organize the bursting mechanism. Bifurcation and basin analyses identify two symmetric chaotic saddle ranges between interior crises and the folds of limit cycles. When quiescent-to-spiking transitions fall within these ranges, chaotic saddles render the full system highly sensitive to parameters, acting as the organizing center for hidden bursting. By tuning the slow adaptation strength, we uncover three transition-path modes: lift-captured double-reversal (LCDR), lift-escape single-reversal (LESR), and direct-captured no-reversal (DCNR). These modes and their combinations classify the observed bursting patterns. These findings show that non-attracting invariant sets can affect bursting dynamics, offering a new perspective on bursting dynamics. Full article

To reduce energy consumption in mine ventilation networks under dynamic air demand, this study proposes an Improved Cuckoo Search (ICS) algorithm for energy-efficient airflow regulation. A nonlinear optimization model is established incorporating airflow balance at nodes, air pressure balance in loops, and fan operating constraints; equality constraints are handled by an exterior penalty function and inequality constraints by an interior penalty function. To overcome standard Cuckoo Search’s insufficient convergence accuracy and premature convergence, adaptive step sizes, an adaptive discovery probability adjustment, and a hybrid update strategy with differential evolution are introduced to enhance global exploration and local exploitation, convergence speed, and stability. The method was validated on an intelligent ventilation platform using field data from the Second Panel of a coal mine in Shaanxi Province. Results show that ICS reduces total power consumption from 482.0 kW to 424.9 kW, achieving an energy-saving rate of 11.85%, and outperforms CS, PSO, and GWO in convergence efficiency, accuracy, and stability. Quantitatively, it converges in 130 iterations (190 for CS, 160 for GWO), with a 0.038 kW objective-function standard deviation (coefficient of variation 0.009%) over 30 runs and 0.22 s per run. The proposed method optimizes airflow distribution while satisfying air-demand constraints, offering a practical approach for energy-efficient mine ventilation. Full article

Indoor service robots are increasingly deployed in indoor environments, yet their performance is influenced not only by robot specifications and control algorithms but also by built-environment conditions and interior finishes. This study proposes a performance indicator framework for service robots in robot-friendly built environments using an evidence-based design approach. A systematic literature review identified 21 sources of evidence related to robot–built-environment interactions and measurable performance outcomes. The evidence was synthesized according to environmental conditions, robot responses or failures, performance outcomes, and measurable outputs. Six indicators were derived: mean sensing-distance accuracy, travel-time delay coefficient, mapped-corner deviation, rated-speed reduction coefficient, path deviation, and cumulative travel-induced damage coefficient. The expert evaluation used a 30-item questionnaire comprising five evaluation criteria. Of the 31 respondents, 26 worked in architectural construction or design and five in robot-related fields. The overall mean score was 4.00 out of 5, and the positive-response rate was 73.8%; mean sensing-distance accuracy received the highest rating. These results show that the framework’s appropriateness and potential usefulness were positively evaluated within this sample. However, they do not demonstrate the empirical validity or field applicability of the performance indicators. Controlled robot experiments remain necessary to establish calculation methods, measurement units, application ranges, and performance thresholds. Full article

This study develops a new passive ventilation system for a passenger train. This ventilation system comprises a supply air system and an exhaust air system; it improves indoor air quality and uses only the pressure field generated by the movement of the train as its energy source. Air from the supply air system enters the exterior upper front of the train and exits at the interior lower lateral of the train. Air from the extraction air system enters the interior upper ceiling of the train and exits at the rear upper exterior of the train. In the study, a train comprising five closed compartments was considered. Each compartment is equipped with 16 seats and two tables, accommodating 16 passengers. In general, a vehicle velocity above 17.75 m/s generally ensures acceptable indoor air quality for a general occupancy of 80 passengers. Full article

Coal mine disaster emergency governance requires sustained coordination among regulators, mining enterprises, and professional rescue forces. This study develops a budget-closed tripartite evolutionary game in which subsidy/support outflows and penalty-revenue incidence are represented explicitly. Replicator dynamics is interpreted as a mean-field approximation of repeated organizational learning, and a cross-product extension is used to examine higher-order synergy. Dynamic stability is assessed as local asymptotic stability rather than classical evolutionary stability. Resilience is quantified using measure-conditioned basin stability P_H(ν), direction-conditioned critical disturbance magnitude Δ_crit(d), and conditional recovery time T_rec. The open form is retained only as a mechanism-isolation benchmark. Under full fiscal closure, the original high-incentive parameter set shifts the stable outcome to E₇ = (0, 1, 1), indicating that enterprise and rescue coordination may persist while strengthened regulation is not self-sustaining. An illustrative closure-consistent parameterization restores E₁/E₈ bistability and yields P_H(U([0, 1]³)) = 0.889, Δ_crit(1, 1, 1) = 0.738, and T_rec = 13.95 under the stated experiment. No locally asymptotically stable interior state arises in either the additive benchmark or the cross-product extension. Sensitivity checks further show that the numerical resilience values vary with the initial-state measure and disturbance direction. The findings suggest that collaborative resilience depends jointly on policy intensity, fiscal incidence, initial coordination conditions, and shock structure. Full article

The electrification of ground transport is advancing under a constraint that is as much geopolitical as technical: the rare-earth elements used in high-energy permanent magnets, and especially the heavy-rare-earth additions required for high-coercivity grades, come from a highly concentrated and recently restricted value chain. This review examines how the imperative to reduce or eliminate rare-earth permanent magnets is reshaping traction-machine design across ground-vehicle segments, from city cars and hypercars to racing prototypes, heavy-duty and mining trucks, and agricultural tractors. Adopting a design-oriented perspective, it links each segment’s torque–speed and cost envelope to coordinated choices of topology, magnet strategy, soft-magnetic and conductor materials, and winding architecture. The principal candidate topologies—interior and surface permanent magnet, induction, synchronous reluctance, permanent-magnet-assisted synchronous reluctance, wound-field synchronous, and emerging axial-flux machines—are compared quantitatively and selected topologies are illustrated through previously published design case studies. The picture is nuanced: permanent-magnet machines still dominate the market, yet in representative like-for-like studies the drive-cycle efficiency penalty of magnet-free machines can be small and wound-field machines are emerging as a leading magnet-free alternative within specific operating envelopes. Full article

This study proposes an Electricity 5.0-oriented supervisory control framework for an interior permanent-magnet synchronous motor (IPMSM) drive that integrates field-oriented control, MTPA, field weakening, loss-minimization control (LMC), speed estimation, and adaptive mode selection. Four operating modes, Performance, Balanced, Eco-LMC, and Resilient, are coordinated according to dynamic, electrical, and sensing conditions. The framework is evaluated under variable-speed operation, load disturbances, motor-parameter variations, DC-link voltage reduction, sensor degradation, and combined disturbances. Performance Mode achieves the lowest speed RMSE of 44.52 rpm, while Eco-LMC reduces iron-loss energy by 26.6% and total modeled electrical losses by 10.2%, with a 2.1% reduction in consumed electrical energy. During sensor degradation, the speed observer maintains an RMSE of approximately 19–21 rpm. In the combined supervisory scenario, only eight mode transitions occur, confirming effective chattering suppression through hysteresis and a 35 ms dwell time. No sustained SVPWM saturation is observed in any scenario. The results demonstrate that adaptive coordination of performance, efficiency, and resilience can improve PMSM drive operation within an Electricity 5.0-oriented control framework. Full article

Long-distance free-surface water-conveyance tunnels require a spatially continuous representation of transient water depth, yet in practice flow is monitored at only a few sections. This study develops a physics-informed neural network (PINN) that reconstructs the transient water-depth field of unsteady free-surface flow in such tunnels from two- or three-point sensors. The one-dimensional Saint-Venant equations, closed with a Darcy–Weisbach steady friction term in hydraulic-radius form, are embedded as a soft constraint in the training loss, so that sparse depth observations are combined with the governing conservation laws to recover the field at unobserved interior and downstream locations. High-resolution finite-volume (FVM) solutions of a 500 m circular tunnel under a flood-rise scenario provide the reference data. The PINN reduces the relative L₂ error at unobserved sections to approximately one-quarter of that of an otherwise identical, physics-free ANN (2.50% versus 10.05% at an interior section; 4.77% versus 13.69% at an extrapolation section). Runs repeated with different random seeds confirm statistical stability at zero noise, while revealing that a minority of trainings at 10% noise converge to spurious solutions. Sensor-placement experiments, including layouts anchored at the true domain boundaries (x = 0 and 500 m), show that boundary anchoring—particularly of the upstream boundary—governs both accuracy and noise robustness: boundary-anchored two-sensor layouts remain accurate in most runs under 10–20% observation noise, whereas interior-only layouts degrade sharply. The method is presented as an offline reconstruction tool; its extension to streaming data assimilation is discussed as future work. Full article

This paper develops and rigorously analyzes a fully discrete upwind interior penalty discontinuous Galerkin (IPDG) scheme for simulating solute transport in two-dimensional variable-order fractional mobile–immobile media. The temporal variable-order Caputo derivative is discretized via a Grünwald–Letnikov approximation in conjunction with a first-order backward difference, while the spatial discretization employs an IPDG method featuring an upwind numerical flux for the convection term and a penalty formulation for the diffusion operator. Under the physically relevant assumption of a divergence-free velocity field, we establish the unconditional stability of the proposed scheme. A comprehensive error analysis in the $L^2$ norm yields a convergence rate of $O(\Delta t+h^{\min (k+1,s)-\chi -1/2})$, explicitly linking the polynomial degree k, solution regularity s, and the penalty variant $\chi$. Numerical experiments in two dimensions are conducted to verify the accuracy and robustness of the proposed scheme in simulating anomalous transport phenomena in subsurface environments. Full article

As nature-based solutions, urban parks mitigate urban heat, yet park-scale cooling can conceal heat stress within activity spaces. Combining field measurements, spatial analysis, and ENVI-met modeling, we examined landscape–microclimate associations in Mochou Lake Park, Nanjing. During 08:00–18:00, the park interior was on average 1.30 °C cooler than the surrounding built-up area, with relative humidity 2.72 percentage points higher. Nevertheless, the Universal Thermal Climate Index (UTCI) indicated at least strong heat stress at all internal points, and mean air temperature ($T_a$) differed by up to 2.22 °C among activity-space types. In fitted models, each 10-percentage-point increase in tree canopy cover corresponded to estimated decreases of 0.12 °C in $T_a$, 1.68 °C in mean radiant temperature (MRT), and 0.44 °C in UTCI, while $T_a$ rose by 0.12 °C per 10 m of distance from the lake. Open space ratio was associated with higher MRT and UTCI, and near-ground permeability ratio with lower UTCI under the study-day wind conditions. A tree canopy cover of approximately 40% in activity spaces emerged as a case-specific, model-derived reference value at which the predicted daytime maximum UTCI remained below the 46 °C extreme heat stress threshold. These findings reveal thermal risks hidden by park-scale averages and can inform climate-adaptive park design. Full article

The 3D geometric documentation of cultural heritage monuments requires spatial datasets that are accurate, complete and suitable for conservation, monitoring, visualization and heritage management. However, complex geometries, occlusions, limited accessibility, vegetation and other field-acquisition constraints often prevent a single surveying technique from providing a complete and metrically reliable representation. In this context, photogrammetry and simultaneous localization and mapping (SLAM)-based mapping provide complementary capabilities, with each method offering advantages and limitations regarding metric accuracy, spatial coverage, detail representation, acquisition flexibility and operational efficiency. This work develops, applies and evaluates a reproducible end-to-end workflow for the metric 3D documentation of complex cultural heritage monuments through multi-sensor integration. The proposed approach combines the metric robustness and visual richness of photogrammetric reconstruction with the rapid acquisition and spatial coverage enabled by SLAM-based mapping, while producing reusable datasets for conservation planning, comparative studies, education and broader heritage applications. The workflow integrates unmanned aerial vehicle (UAV) and close-range photogrammetry, SLAM-based mapping and geodetic control within a common reference system and is demonstrated through the documentation of a historic monastery. Both datasets showed centimetre-level agreement with geodetic observations, while photogrammetry yielded fuller exterior coverage and higher-quality texture, and SLAM enabled rapid interior coverage. The CH-PhotoSLAM3D dataset is released to support reproducibility and further research. Full article

Forest edge effects are commonly interpreted as radial gradients from the edge toward the interior, but this assumption may oversimplify the spatial organization of heterogeneous tropical forest fragments. Here, we integrated field-based phytosociological data with Sentinel-2 spectral indices to evaluate whether edge-related structural interpretation depends on analytical scale in Semideciduous Seasonal Forest fragments embedded in the Brazilian Cerrado. Five fragments were analyzed using transect-based plots and continuous pixel-level modeling. Basal area showed a strong positive correlation with the Normalized Difference Vegetation Index (NDVI) (r = 0.95), supporting its use as the main spectral proxy for basal-area-related structural variation. Plot-level segmented regression detected statistical transitions along the edge–interior gradient, with breakpoints ranging from approximately 13 to 39 m. However, pixel-level modeling revealed scale-dependent responses, including shorter estimated transition distances in the rural Ipameri fragment (IF) and the Campo Alegre de Goiás fragment (AC), an intermediate transition in the Caldas Novas fragment (CN), a longer estimated transition distance in the UEG–Ipameri fragment (IP), and high internal heterogeneity without a single dominant radial transition in Panga. The first two axes of the Principal Component Analysis (PCA) explained approximately 81% of the total variance, reinforcing the structural–spectral correspondence. These findings show that edge-related spectral–structural patterns are detectable but are not adequately represented by fixed radial zones alone. Pixel-level Sentinel-2 modeling provides a complementary spatial framework for interpreting edge-related heterogeneity in fragmented tropical forests when integrated with field-based structural data. Full article

This study presents a high-efficiency T-type three-level inverter for interior permanent magnet synchronous motor (IPMSM) drive applications, featuring a comprehensive performance comparison with a conventional two-level inverter. To address the high switching losses and noticeable harmonic distortion typically associated with conventional two-level configurations, the T-type architecture is developed and evaluated. First, PLECS simulations are conducted to verify the proposed dual-loop control architecture, which integrates field-oriented control (FOC), space-vector pulse-width modulation (SVPWM), and a neutral-point voltage balancing mechanism. Subsequently, a 2.2 kW experimental platform is constructed using silicon carbide (SiC) wide-bandgap (WBG) semiconductor devices. To characterize the dynamic switching behavior of the adopted SiC MOSFETs, a dedicated double-pulse test (DPT) platform is developed to evaluate their switching losses and determine appropriate gate-drive parameters. In addition, the digital control firmware is implemented on a digital signal processor (DSP) platform. The dual-loop control algorithms, SVPWM strategy, and two-layer protection framework are implemented as real-time executable routines, enabling close integration of the control software and hardware platform. Finally, motor drive experiments at switching frequencies of 20 kHz and 40 kHz are performed to validate the proposed system. The experimental results demonstrate that the developed architecture significantly reduces phase-current total harmonic distortion (THD) and improves overall energy conversion efficiency compared with a conventional two-level inverter, confirming its potential for high-efficiency next-generation electric vehicle applications. Full article

Urban heat islands in densely built cities pose growing risks to public health and energy demand. Urban parks are key nature-based solutions, yet empirical evidence on park cool island (PCI) effects intensity and extent in compact cities remains limited. This study evaluated PCI for 12 pocket-to-medium/large urban parks in central Taipei, Taiwan. Land surface temperature (LST), mean radiant temperature (MRT), and effective temperature (ET) were measured along transects from park interiors into surrounding areas and linked to local environmental conditions. Parks showed PCI intensity in LST with an average cooling of 4.23 °C and an average cooling of 0.3 °C in ET; MRT cooling was weaker and spatially inconsistent. The cooling of LST extended to about 60 m beyond the park’s edges, while the cooling of ET reached approximately 150 m. In addition, the results show that shade and relative humidity are significant factors affecting PCI, and pervious pavement and wind speed also contribute to cooling LST and ET. The field observations provide evidence that urban parks contribute cooling effects and might reduce the risk of heat hazards. Full article