Search Results (531)

Wound-rotor synchronous machines (WRSMs) offer a promising, magnet-free alternative for safety-critical transportation sectors like electric vehicles (EVs) and marine propulsion. While multiphase structures enhance fault tolerance in these applications, conventional WRSMs still suffer from reliance on maintenance-prone slip rings and brushes. Brushless multiphase self-excitation presents a compelling solution, but it introduces a critical design challenge: ensuring decoupled control between the torque-producing (αβ) and magnetizing () subspaces to prevent severe performance degradation. To address this cross-coupling issue, this paper proposes a 20-slot/18-pole five-phase architecture. By exploiting distinct spatial harmonics, the stator generates two independently controlled magnetic fields with a dedicated rotor harmonic winding. An integrated diode rectifier then seamlessly converts the induced AC voltages into the required DC field excitation. Extensive finite-element analysis (FEA) using ANSYS Maxwell is conducted to validate the design and rigorously evaluate subspace cross-coupling. Simulation results confirm that the proposed machine meets design specifications, demonstrating stable self-excited operation, acceptable efficiency, and representative fault-tolerant operation under a single open-phase condition, thereby confirming the electromagnetic feasibility of the proposed topology as a promising magnet-free candidate for future alternatives to PMSM-based traction solutions. Full article

The efficiency of airport resource allocation is improved through the establishment of a scientific multi-granularity configuration scheme for flight slot coordination parameters. In this study, a collaborative configuration method for hourly and 15 min coordination parameters is proposed, with Beijing Capital International Airport serving as a case study. Short-term traffic clusters are frequently omitted by traditional hourly parameters, thereby leading to sudden delay surges. First, local delays were extracted from March 2024 Automatic Dependent Surveillance-Broadcast (ADS-B) trajectory data. Subsequently, a delay prediction model was constructed through the integration of a non-stationary queuing model and a gradient boosting regression tree. Second, simulated timetables were generated via a Monte Carlo method under various parameter combinations. With a constant daily flight volume utilized as the experimental baseline, a mapping relationship was established between parameter combinations and expected local delays. Finally, feasible delay regions were delineated and interpretable configuration rules were extracted via a decision tree to maximize schedule flexibility. It was indicated by the results that at an hourly parameter of 70 flights, the target delay is maintained below 8 min by tightening the 15 min parameter to 19 flights. The findings suggest that average load is controlled by hourly parameters, while traffic clustering in high-load scenarios is effectively suppressed by 15 min parameters. A quantitative reference is provided by this method for the configuration of multi-granularity time parameters at hub airports. Full article

Short-term water demand forecasting is a key issue for the management of smart water networks, particularly in the context of remote control and active regulation. This study analyses a real-world dataset of water demand coefficients, collected at 15 min intervals, from a municipality in Southern Italy serving approximately 73,000 inhabitants. The proposed model, based on Gaussian Process Regression (GPR) with a Rational Quadratic kernel (RQ), is compared with a statistical benchmark constructed using average patterns for each time slot by the application of the Gauss Distribution. The results show a reduction in RMSE and MAE and a better ability to track the daily dynamics of demand using the GPR approach. Full article

Continouous unmanned aerial vehicle (UAV) missions are fundamentally limited by Lithium-Polymer (LiPo) battery endurance under intermittent and power-constrained renewable energy conditions. This paper proposes an integrated energy management and charging framework for a photovoltaic (PV)-powered mobile station equipped with a hybrid energy storage system (HESS) and an automated battery replacement (ABR) mechanism. A lexicographic priority-based allocator sequentially serves ABR actuation, multi-slot LiPo charging, and Brushless DC (BLDC) propulsion, while the HESS compensates for PV intermittency. At the charging level, a constraint-aware constant current–constant voltage (CC–CV) strategy is enhanced by an adaptive neuro-fuzzy inference system (ANFIS) trained on optimization-derived labels using battery temperature and its rate of change, thus enabling anticipatory thermal current derating with smooth, discontinuity-free control action. Anti-windup proportional–integral (PI) regulation and bumpless mode transfer ensure stable CC-to-CV transitions. An event-triggered emergency mode accelerates battery readiness via a max-first selection policy. Comparative simulations against a PSO/DE-optimized PID benchmark over a full diurnal PV cycle demonstrate that the ANFIS controller reduces the CC-mode current tracking root-mean-square error (RMSE) by up to 96.9%, delivers higher charge throughput, and lowers battery degradation proxies, including SOC-weighted thermal dose and equivalent full cycles (EFC). The proposed framework reliably sustains continuous charge–swap–recharge logistics under fluctuating renewable generation. Full article

Secure vehicle-to-vehicle communication is essential for electric-vehicle platoons because broadcast wireless links may expose safety and control messages to passive eavesdropping. This paper investigates a physical-layer security (PLS) framework for electric-vehicle (EV) platoons under Rician fading, representing the line-of-sight conditions common in highway platooning. The proposed Jamming-Aided Cooperative Relay Selection (JACRS) framework uses an amplify-and-forward relay, destination-assisted full-duplex friendly jamming, residual self-interference modelling, and a strict total transmit power budget. Relay selection is evaluated using a full-channel state information (CSI) secrecy-selection benchmark, a practical legitimate-link CSI rule, and a deterministic platoon-geometry-aware rule based on Cooperative Adaptive Cruise Control (CACC) position information without instantaneous eavesdropper CSI. Monte Carlo simulations, supported by semi-analytical secrecy-outage and deterministic-slot benchmarks, compare the proposed scheme with Rayleigh and no-jamming amplify-and-forward (AF) baselines. Under the simulated geometry, the scheme achieves a peak ergodic secrecy rate close to 5.0 bps/Hz at 40 dBm and reduces interception risk by 78.07% relative to the Rayleigh baseline. Relay diversity reduces secrecy outage from 14.14% to 0.04% under full CSI and to 0.22% using legitimate-link CSI. The geometry-aware rule reduces the gap between practical legitimate-link selection and the full-CSI benchmark, indicating that platoon position information can improve relay selection under the tested conditions. Full article

Public health emergencies require spatial crowdsourcing platforms to finish urgent tasks while limiting unnecessary movement across regions. Most online task assignment studies focus on profit, travel distance, latency, task coverage, or service quality. However, isolation sensitive scenarios need a different assignment goal. In such scenarios, regional crossings should be directly controlled during worker–task matching. This paper studies an isolation sensitive online task assignment problem in spatial crowdsourcing. The service space is modeled as a regional adjacency graph. The matching objective combines cross-region movement cost, an urgency reward for delayed task completion, and a dummy no-assignment cost for carry-over decisions. To handle dynamic arrivals, a time-sliced online process is used. Unfinished tasks are carried over to later time slots, and the priority of each carried-over task increases with waiting time. Based on this framework, we design two algorithms. OnlineKM serves as the basic priority-aware online matching algorithm. OnlineKM builds a matching problem in each time slot and applies KM-based partial matching with the information currently available. OnlineARC further uses δ-balanced adaptive regional coarsening. OnlineARC merges adjacent regions according to recent supply–demand balance before matching. This step adjusts the regional granularity used for movement cost evaluation and helps keep assignments close to local regions when regional merging is suitable. Experiments are conducted using a real-world task locations dataset from a 2022 COVID-19-related scenario in Changchun, with simulated worker availability and online arrivals. The results show that the proposed methods usually reduce the combined assignment objective value under the tested settings. The service quality and movement control metrics show that OnlineARC reduces the cross-region assignment ratio and average hop distance while maintaining a high task completion rate under the representative setting. OnlineKM improves running efficiency through time-sliced matching, while OnlineARC provides a trade-off between adaptive coarsening cost and locality-aware movement cost evaluation. These results suggest that adaptive regional coarsening can serve as a practical heuristic for locality-aware online task assignment in isolation sensitive spatial crowdsourcing under suitable worker–task distributions. Full article

To improve the directional propagation of blasting-induced cracks in sandstone and reduce over-excavation, under-excavation, and surrounding-rock damage caused by conventional circular blastholes, circular and V-shaped slotted blasthole models were established in LS-DYNA. The ALE fluid–solid coupling algorithm was adopted to investigate the effects of slot angle on the effective stress field, crack propagation pattern, and crack control index. The stress field theory at the tip of the V-shaped slot was further used to explain the directional cracking mechanism. On this basis, a two-hole V-slotted blasting model is established to analyze the influence of hole spacing on crack penetration. The results show that the V-shaped slot can form an obvious stress concentration at the tip, which changes the crack from approximately isotropic extension to directional extension along the direction of the slots. Under the present two-dimensional homogeneous sandstone model with simultaneous initiation, the 60° slot angle corresponds to the highest peak effective stress and crack control index. For the synchronized two-hole model, when the hole spacing is 70–90 cm, namely the ratio of hole spacing to blasthole diameter is approximately 14–18, the inter-hole crack penetration effect is better, and the proportion of effective cracks along the slot direction is about 80%. These results provide baseline numerical references for sandstone-controlled blasting parameter design under the modeling conditions of this study. Full article

Introduction: Freshwater ecosystems are among the most threatened worldwide, with river fragmentation, primarily caused by dams and weirs, identified as a major driver of biodiversity loss. This issue is particularly acute in Europe, where more than one million instream barriers disrupt longitudinal connectivity and compromise the movement of migratory fish. Fishways are widely implemented to mitigate these impacts, yet attraction efficiency at fishway entrances remains poorly understood, especially for Iberian potamodromous cyprinids, a group facing severe conservation pressures. Objective: This study aims to investigate how hydraulic conditions and social context influence the attraction and passage behavior of Luciobarbus bocagei, a rheophilic potamodromous cyprinid endemic to the Iberian Peninsula, in an experimental Vertical slot fishway (VSF) entrance. Methodology: Experiments were conducted in a controlled flume equipped with a VSF entrance design. Two hydraulic scenarios were tested, a Low Head Drop (LD) and a High Head Drop (HD), under a constant discharge of 34 L/s. A computational fluid dynamics (CFD) model was used to characterize and compare the flow field hydrodynamics. Fish were tested individually and in groups of three to assess the role of social dynamics. The metrics collected included time to first approach, first attempt, time to first successful passage, attraction efficiency, and passage efficiency. Cox proportional hazards models were applied to evaluate treatment effects. Results: Preliminary results showed that social context influenced fish attraction behavior. In the two hydraulic scenarios, individuals tested alone tend to exhibit lower likelihoods of approaching, attempting, and successfully negotiating the fishway compared to fish in schools. Delays were also evident for attempts and successful passages, with LD_Ind performing the worst. Conclusions: These findings highlight the importance of hydraulic conditions and social behavior in shaping attraction efficiency. They underscore the need to integrate species-specific behavioral ecology into fishway design, operation, and attraction assessment, acknowledging that fish attractivity is influenced by environmental and ecological factors beyond fishway structure, particularly in Mediterranean river systems where fragmentation pressures are high and potamodromous cyprinids are at risk. Full article

Introduction: The restoration of river connectivity through fishways is essential for the conservation of native freshwater fish, yet it may inadvertently facilitate the upstream spread of non-native invasive species. This trade-off is particularly relevant in Iberian river systems, where invasive cyprinids pose a growing ecological threat. Objective: In this study, we evaluated the potential for selective fish passage in a full-scale vertical slot fishway (VSF), aiming to promote native species movement while limiting invasive taxa. Methodology: Experimental trials were conducted with the common carp (Cyprinus carpio), a widespread invasive species, and the results were compared with those of the native Iberian barbel (Luciobarbus bocagei). Two fishway configurations were tested, both with high slope (15.2%) and high turbulence (volumetric power dissipation >150 W m⁻³), differing in water depth (0.55 m and 0.80 m). Fish passage performance was assessed through behavioural metrics, including motivation to attempt passage, ascent success, and transit time, using a time-to-event framework. Hydrodynamic conditions were characterised through computational fluid dynamics modelling. Results: The results revealed marked interspecific differences. Common carp exhibited significantly lower motivation to initiate passage and extremely limited success: no individuals ascended the shallower configuration, and only one ascended the deeper configuration. In contrast, Iberian barbel demonstrated high motivation and passage success under both configurations, particularly in more turbulent conditions. Conclusions: These findings suggest that manipulating key hydraulic parameters can create selective passage conditions that favour rheophilic native species while hindering limnophilic invasive taxa. This ecohydraulic approach offers a promising strategy to reconcile the restoration of longitudinal connectivity with the control of biological invasions. Nevertheless, further research under field conditions and across a broader range of species is required to validate and generalise these findings. Full article

The conventional robotic position control is gradually being replaced by force control, which is commonly used in humanoid robot applications that require force interaction with the environment, force transmission, or contact. A high-back-drive-efficiency actuator with a high-torque-density permanent magnet motor connecting the low-ratio planetary reducer is widely applied in interactive robotic systems without a torque/force sensor. This paper proposes a high-torque-density permanent magnet motor with an external rotor structure, which can realize torque enhancement by the increased air-gap diameter and better space utilization by the internal planetary reducer, i.e., the reducer inside the stator. First, the motor topologies with different slot/pole number combinations are introduced. Then, the optimization of a slot/pole number combination is elaborated for the maximum torque and torque mass density. In addition, the influence of the slot/pole number combination on the torque characteristic and overload capability is investigated by the finite element (FE) method. The experimental results of the prototype motor are provided to verify the analysis. Full article

Expansion screen pipe is a new sand control completion technology. In this paper, the optimization design of the slotted structure of the screen pipe is studied. Mechanical models for both seamless base pipes and slotted base pipes have been established based on elastic-plastic mechanics. The finite element simulation analysis of the expansion process of screen pipes with different slotted structures is carried out, and the relationship among the length of the slot L, the number of slots N, the internal pressure P and the maximum stress at the slot end σ is obtained. The principle and optimization process of the NSGA-II algorithm are introduced. Furthermore, a multi-objective optimization model is formulated, taking P and σ as the objective functions, and the NSGA-II algorithm is applied to optimize this model. By analyzing the obtained optimization results for the screen pipe with an outer diameter of 68 mm, the optimal slotting parameters are L = 137 mm and n = 12. For the optimal slotted structure obtained, P is greater than the minimum expansion initiation pressure, and σ is less than the ultimate tensile strength, which indicates that the optimal solution meets the requirements of both theoretical analysis and engineering practice. In this paper, the NSGA-II multi-objective optimization algorithm is introduced into screen pipe structure optimization for the first time. The structural optimization method of expandable screen pipe proposed in this paper improves the design level and efficiency of the screen pipe. At the same time, it provides a new means for research on screen pipe structures in the fields of petroleum and exploration. Full article

This paper presents a fully integrated E-band (83/95 GHz) diplexer realized in STMicroelectronics’ BiCMOS 55 nm technology. The design directly addresses the critical trade-off between miniaturization and the performance required for high-frequency on-chip systems. The key innovation is a novel patch resonator optimally exploiting the multi-layer structure of the technology’s Back-End-Of-Line. It achieves significant compactness by jointly combining two distinct miniaturization techniques: slotted structures and mushroom-type capacitive loading. This method results in an impressive 77% size reduction compared to conventional designs. Furthermore, we introduce precisely controlled transmission zeros (TZs) to maximize inter-band isolation. The fabricated diplexer achieves a remarkably narrow fractional bandwidth (FBW) of 8.2%—the lowest reported to date for integrated BiCMOS/CMOS E-band implementations—and a robust inter-band isolation exceeding 25 dB, while demonstrating excellent return loss (better than 25 dB). Hence, this work validates a highly compact and scalable approach for integrated E-band transceivers, paving the way for future 6G front-end applications. Full article

This paper investigates secure and low-latency communications in UAV-mounted simultaneously transmitting and reflecting reconfigurable intelligent surface (STAR-RIS)-assisted urban vehicular networks, where severe blockage, high vehicle mobility, eavesdropping threats, and delay-sensitive traffic services coexist. In the considered system, the UAV is used not only as an aerial carrier for the STAR-RIS but also as a mobile intelligent control node that can dynamically adjust its horizontal aerial position according to vehicle distribution, blockage conditions, and eavesdropping threats. First, a UAV-STAR-RIS-assisted vehicular communication system model is developed by jointly considering urban blockage, vehicle mobility, passive eavesdropping attacks, queueing dynamics, and UAV flight constraints. Then, a high-dimensional, non-convex, and strongly coupled dynamic optimization problem is formulated to maximize the long-term average secure and low-latency utility through the joint optimization of the UAV trajectory, the STAR-RIS transmission–reflection partition ratio, the phase-shift matrices, and the transmit power allocation. Furthermore, the problem is modeled as a Markov decision process with continuous state and action spaces, and a hierarchical constrained soft actor–critic (HC-SAC)-based joint control algorithm is proposed to enable adaptive UAV movement, STAR-RIS configuration, and power control in complex dynamic environments. Simulation results demonstrate that the proposed method outperforms DDPG and several structural benchmark schemes. In the representative evaluation, the proposed HC-SAC achieves an average delay of 10.85 slots and a secrecy outage probability of 0.7160, compared with 11.72 slots and 0.8501 for PPO, and 11.94 slots and 0.8599 for DDPG. Although PPO provides the highest average secrecy rate and successful service ratio, the proposed method still maintains a competitive secure communication capability and service reliability. A normalized composite utility analysis further shows that HC-SAC attains the highest utility value of 0.9254, indicating a more favorable security–latency trade-off in complex urban vehicular scenarios. Full article

To address flow instability induced by tip leakage vortex breakdown in high thrust-to-weight ratio aero-engine compressors, this study conducts numerical investigations into the DTR transonic compressor rotor. The unsteady evolution of the tip leakage vortex and the corresponding stall inception mechanism under near-stall conditions are revealed. Active flow control using single-slot and dual-slot endwall synthetic jets is further explored. Results show that an optimized single synthetic jet slot improves the compressor stability margin by 11.24% and design-point efficiency by 0.57%. To address the flow instability on this, synergistic excitation using two slots positioned at 25% and 50% axial chord length further suppresses leakage vortex breakdown and passage blockage, raising the stability margin by an additional 13.68% and efficiency by 0.72% compared to the optimal single-slot configuration. For the baseline compressor under near-stall conditions, tip leakage vortex breakdown occurs near 25% axial chord, causing severe flow deterioration. With synthetic jet actuation, low-energy fluid at the tip is blown away or sucked out, delaying vortex breakdown and reducing flow losses, thereby enhancing stability without compromising aerodynamic efficiency. The underlying mechanism is that, during the blowing phase, the jet splits the large-scale leakage vortex and removes the low-energy blockage region; during the suction phase, it extracts the fluid trapped in the tip clearance, preventing re-accumulation of low-energy fluid. These findings provide theoretical guidance for stall suppression and high-performance design of transonic compressors. Full article

A Software-Defined Network (SDN) renders flexible traffic engineering, but consumes a lot of energy. There is an overhead on the control-plane because flow rule updates are always performed and there is energy consumption by the forwarding hardware. Current energy-aware SDN methods mostly focus on Static or Greedy optimizations. This can cause too many Ternary Content-Addressable Memory (TCAM) updates and unstable rule churn when traffic changes over time. This article introduces a Dynamic Flow Rule Placement (DFRP) framework for real-time energy optimization in SDN. It reduces network energy usage, TCAM update costs, and rule churn all at the same time. The suggested framework uses a convex relaxation method to take decisions on binary switches, links, and rule placement. It also uses a minimum-edit round scheme that only allows small rule changes between time slots. To further reduce instability in the control plane, batch scheduling and receding horizon optimization (RHO) techniques are used. The system uses predicted traffic for future time slots to make decisions, but only the actions for the current time slot are executed. The experiments are carried out on two real-world dynamic SNDlib topologies such as Germany50 and Nobel-Germany, using 288 five-minute traffic matrices over a one-day period. Comparative results against Static and Greedy baselines show that DFRP saves approx. 30% energy while cutting down on TCAM update overhead and rule churn by approx. 20%, consistently across both the networks. Hence DFRP can be applied on dynamic traffic large-scale networks for stable and energy-efficient SDN operations. Full article