The study of lane-changing behaviour is crucial for road efficiency, safety, and traffic flow, especially at highway interchanges where lane-changing actions significantly impact capacity and safety. In mixed traffic with human-driven and autonomous vehicles (AVs), the traditional model of Minimising Overall Braking Induced by Lane changes (MOBIL) fails to account for human decision making imprecision. This study is an analysis of lane-changing characteristics using naturalistic driving data and enhances MOBIL by integrating dynamic fuzzy thresholding and collaborative decision making. A fuzzy logic-based lane-changing model for human drivers is developed, incorporating multivehicle data and lane-changing urgency, and has been adapted for AVs. Using Simulation of Urban Mobility (SUMO)–Python microsimulation, results show that a 50% AV penetration rate improves interchange efficiency by 15% and reduces conflicts by 20%, compared with human-only scenarios. These findings aid in optimising traffic management for mixed-traffic interchanges.

Traditional fatigue monitoring methods often suffer from in-sufficient real-time performance and low accuracy. To address these limitations, this study proposes a novel facial feature-based approach for driver fatigue monitoring and prediction, aiming to enhance both detection accuracy and real-time responsiveness. Eye features are one of the key indicators for assessing driver fatigue. This research first introduces a new quantitative metric based on eye features to improve the stability and robustness of fatigue characterization. Subsequently, a pre-trained facial keypoint detection model is employed to extract dynamic eye and mouth features, constructing a novel fatigue index that dy-namically reflects real-time changes in facial behavior for more accurate fatigue state assessment. To further improve prediction accuracy, a lightweight CNN-BiLSTM-Attention hybrid model is designed. This model integrates spatial features extracted by convolutional neural networks (CNN) with temporal dependencies captured by a bidirectional long short-term memory (BiLSTM) network, while an attention mechanism is introduced to optimize fatigue-level prediction capabilities. To validate the proposed method, experiments were conducted with six drivers, each lasting no less than 20 min. The results demonstrate that the new fatigue index and prediction model can accurately capture dynamic changes in driver fatigue levels with low prediction error rates. Finally, we also verified the effectiveness of the fatigue index through validation in a public dataset.

In the article, the comparative study of core loss and permanent magnet (PM) loss in fractional-slot permanent magnet vernier machines (PMVMs) and permanent magnet synchronous machines (PMSMs) for in-wheel drive are investigated. Firstly, the definitions of “Family” and “Group” for armature magnomotive force harmonics in fractional-slot PM machines are proposed, and the relationship between PMVM and PMSM is illustrated, where the generalized PMSM concept is proposed. Secondly, the core and and PM losses are calculated and compared by the theoretical and finite-element analysis (FEA) methods. The contribution of each harmonic on the core and PM losses is extracted, where the subharmonic and slot-harmonic that not contributed to the torque are mostly responsible for core and PM losses. Thirdly, the influence of stator slot opening, flux barriers, and PWM control on the core loss, PM loss, and torque are all investigated. The losses of PMVM and PMSM under various conditions is calculated and exhibited, and the PM loss is much severer in PMVM. Finally, two prototypes of PMVM and PMSM are manufactured and tested, and the total losses and efficiencies are measured, where the experiments agree well with the FEA and theoretical analysis.

Accurate prediction and causal analysis of road crashes are crucial for improving road safety. One critical indicator of road crash severity is whether the involved vehicles require towing. Despite its importance, limited research has utilized this factor for predicting vehicle towing probability and analyzing its causal factors. This study addresses this gap by predicting the probability of vehicle towing in road crashes based on road scene features and identifying key causal factors. Utilizing the Transportation Injury Mapping System (TIMS) dataset from California, USA, encompassing 12 years, 14 relevant features, and over 2 million road crash records, research team developed a prediction model using advanced gradient boosting techniques. Our model outperforms Random Forest, GBDT, and XGBoost in predictive accuracy. Employing the Shapley Additive Explanation (SHAP) method, researchers elucidate seven key factors influencing towing necessity. These findings introduce a novel predictive approach and offer valuable insights for road crash risk assessment and road safety planning.

In this paper, the thermal characteristic and loss distribution of permanent magnet vernier machines (PMVMs) and permanent magnet synchronous machines (PMSMs) are investigated for in-wheel direct drive. Firstly, the topologies and heat dissipation design of the outer-rotor in-wheel motors are illustrated. Then, the losses of two selected motors under typical conditions are calculated. Besides, the loss distribution feature is targeted too, where the PM loss is stressed in PMVM and core loss is focused in benchmark PMSM. Secondly, the assembly structure of in-wheel motors is described, where the heat path is through the stator support to motor frame directly without air, so the thermal resistance can be largely reduced and the heat can be transferred easily. In order to verify the analysis, a model is established to calculate the thermal conductivity, and the air-gap thermal conductivity is focused. Besides, the finite-element model is also calculated to identify the temperature difference between PMSM and PMVM. Finally, two prototypes of PMVM and benchmark PMSM are manufactured and tested. Then, the experimental results can match well with finite-element analysis (FEA) and theoretical analysis.

Existing approaches to identifying key nodes in bus and subway systems primarily emphasize topological structure, often overlooking functional attributes and failing to account for group relationships among critical nodes. This limitation hinders a comprehensive assessment of systemic network risk. To address these shortcomings, we construct a weighted composite network using a generalized cost metric that reflects the difficulty of transit between stations. The proposed MCGM model integrates three topological indicators - degree centrality, median centrality, and kernel degree - with three functional indicators - boarding volume, capacity, and accessibility - to identify key nodes. These nodes are subsequently clustered using the ECG algorithm, and cluster importance is evaluated based on network toughness. The results reveal strong interdependencies among key nodes, which tend to form banded or clustered spatial patterns. Notably, Cluster 2 occupies a central position and contributes 5.45% to overall network toughness, offering valuable insights for emergency resource allocation and post-disaster recovery planning.

In this article, the thermal analysis of two permanent magnet machines, permanent magnet vernier machine (PMVM) and synchronous machine (PMSM), is carried out for in-wheel drive application. An improved heat dissipation design is proposed and utilized for the in-wheel motors. Firstly, the in-wheel motors are designed and compared, afterwords, two prototypes of PMVM and PMSM are manufactured. Secondly, the losses of two motors are investigated, e.g., copper loss, core loss, and PM loss. The loss distribution feature of two motors has figured out. Thirdly, the single hub-bearing design for two in-wheel motors is illustrated. Besides, the heat transfer coefficient is further calculated, then the lumped model of single-bearing design is clarified, where the good heat dissipation effect of single hub bearing can be demonstrated theoretically. To further validate the feasibility of analysis above, the CFD models of two in-wheel motors are built. The temperature rises under various typical operation conditions for in-wheel drive are simulated and compared. It is noted that the PM temperature rise in PMVM is much severer than that in PMSM, which threaten the operation safety. Finally, the efficiency maps, temperature rise of windings and rotor parts are measured, respectively, which can agree well with the simulated results. This article aims to provide a comprehensive thermal analysis of PM machines with improved heat dissipation design for in-wheel traction application.

In electrical vehicles (EVs), permanent magnet synchronous motor (PMSM) should have wide constant power speed range (CPSR), wide high efficiency region and high fault tolerant capability. However, traditional PMSMs do not both have these two characteristics. The axial split phase (ASP) PMSM with high inductance and good fault tolerant performance has been proposed and received attention in electrical vehicles (EVs). However, its performances under the whole speed range are still unclear, which is very critical for PMSM in EVs. In this article, the performance of ASP-PMSM under the whole speed range are comprehensively studied. At first, the critical factors that influence the field weakening performance are investigated. Then, the losses of ASP-PMSM at different operating conditions are analyzed and compared with that of fractional slot concentrated winding (FSCW) motor and integral slot distributed winding (ISDW) motor by theoretical analysis and finite element analysis (FEA). It is revealed that the ASP-PMSM both have high inductance and low loss at deep field-weakening region. At last, the loss and efficiency under the whole speed range are investigated carefully by FEA. It is verified that the investigated ASP-PMSM has the characteristics of wide CPSR and high efficiency region.

To mitigate the safety risks and increase the torque capability as well for electric aircraft propulsion system, a novel axial-flux permanent magnet vernier machine (PMVM) with H-core stator modules is proposed and analyzed in this article. The stator of this machine is totally composed of H-core modules with separate toroidal windings, which can isolate all stator modules physically and mostly prevent the propagation of faults. Besides, due to the flux modulation effect, the output torque also increases and both the output performance and safety can be guaranteed. Firstly, the machine topology and working principle are analyzed and provided, and the feasible slot/pole combinations, armature windings, gear ratio are derived and analyzed. Secondly, to fairly compare the performances of this modular axial-flux machine, a benchmark YSAS axial-flux machine is selected and designed as the comparison candidate. The comprehensive performance, such as the no-load back-EMF, inductance, output torque, losses, and efficiency et al., is simulated by finite-element analysis (FEA).

This paper proposes a torque-coupled axial-flux permanent magnet (AFPM) motor with a wide speed operating range. The motor system incorporates an innovative and adaptive mechanical flux weakening method comprising a single-stator dual-rotor type AFPM and a magnetic coupler with a rigid stopper. The two components are concentrically integrated to maximize radial space utilization, enabling the torque generated by both rotors to collaboratively act on the load side through the magnetic coupler. As the load torque varies, the torque of both rotors is also regulated. This enables the automatic adjustment of the angular displacement between the two rotors through the magnetic coupler, thereby changing the combined electromotive force (EMF) to achieve a wide speed range flux weakening operation. In addition, the implementation for calculating the flux weakening degree during constant power operation is presented. Finally, the effectiveness and feasibility of the design are validated through three-dimensional finite element simulations.

This article provides a tradeoff study of torque and rotor losses, including the permanent magnet (PM) loss and core loss, in permanent magnet vernier machines (PMVMs), for in-wheel traction. Firstly, the analytical models of PM loss, core loss, and torque are established, and the core loss is calculated by three methods. Besides, the influencing factors on toque and losses are extracted. Secondly, the influence of stator and rotor topologies on torque and losses is studied, and the contribution of flux density harmonic on PM loss, core loss, and torque in various topologies and slot-pole combinations are calculated and compared, where both sub-harmonics and slot harmonics are mostly responsible for core loss and PM loss. Next, the rotor flux barrier in d-axis path is introduced. The influence of flux barrier dimensions on air-gap flux density, core loss, PM loss, and torque is carried out, and it shows that the modulated flux density is reduced with flux barrier, which helps to reduce PM loss. Moreover, the decay rates of losses and torque under the typical conditions are extracted. The PM loss has the dramatic decrease compared with the other ones, but the torque also decreases slightly, which can validate the applicability and correctness of the rotor flux barrier. Finally, a PMVM and a benchmark PMSM are manufactured and tested to validate the theoretical analysis and finite-element analysis (FEA). This article aims to provide the tradeoff design between torque and losses, and introduce a flux barrier solution to alleviate the design conflicts in PMVM for in-wheel traction applications.

Electrical machines are essential components for the electric aircraft propulsion system, and both output performance and fault-tolerance are indispensable for electrical machines. In this paper, two permanent magnet vernier machines (PMVMs) with various multiple E-core stators are proposed and compared. Both stators are completely composed of E-core modules, but the phases of the conventional one are distributed circumferentially, and the counterpart of the phase-unit axial-modular machine is axially distributed, where each phase is also composed of several E-core modules. When the fault occurs in one module, this can be easily cut and replaced, which exhibits superior fault-tolerance. Firstly, the proposed modular machine topology is illustrated and summarized, and the feature of each kind is further investigated. Secondly, the two machine topologies are listed and compared in details, and the working principle is also validated by theoretical analysis. Afterwards, performance comparisons between the two modular machines are carried out, including the no-load and on-load performance, e.g., no-load back-EMF, inductance, torque characteristic, and power factor. Based on these theoretical and finite-element analysis (FEA), the characteristics of two modular machines can be then extracted. Eventually, the prototype with E-core modules were manufactured and tested to further verify the performance of two modular machines, and the experimental results have a good agreement with the analysis before.

This paper proposes the intrinsic coefficient of power factor in permanent magnet vernier motors (PMVMs) influenced by slot-pole combinations for in-wheel direct drive application. To start with, the theoretical expression of power factor under typical conditions is derived, and the dominant influencing coefficients are extracted. Secondly, each inductance component is calculated theoretically, eg. air-gap main inductance, slot leakage inductance, etc. Based on previous derivation, the intrinsic coefficient of power factor is extracted, which represents the high-power-factor ability and be utilized in the initial machine design. It is influenced by the armature poles, armature magnetomotive force (MMF) harmonic spectra, winding factor, and air-gap permeance. Moreover, the slot-pole combinations with various high-power-factor ability are illustrated, in which, the ones with coil-pitch of two-slot pitches overwhelm. In order to validate the theoretical analysis, several PMVM model candidates with various slot-pole combinations are selected and simulated by finite-element-analysis (FEA). Finally, the prototype of PMVM with 28p18s and benchmark PMSM with 28p24s were manufactured and tested for experimental validation. Overall, this paper aims to provide a guideline to select the slot-pole combinations with high-power-factor ability, particularly in PMVM, for in-wheel direct drive.

This article proposed and analyzed a novel phase-unit axial-modular permanent magnet vernier machine (PUAM-PMVM) with integral-slot non-overlapping concentrated windings (ISNOCW) for direct-drive applications. In PUAM-PMVM, all phases are separated and distributed along the axial direction with a fixed mechanical angle between two adjacent phases. Firstly, the machine topology and working principle are illustrated and the theoretical expressions are derived. Besides, the characteristic of slot-pole combinations for PUAM-PMVM is summarized, and the integral gear ratio is obtained. Moreover, the topology extension is also deeply investigated, including the multi-phase, multiple three-phase windings, and hybrid-modular stator designs. Secondly, the optimization and analysis in terms of slot-pole combinations, PM configurations, and slot opening width are conducted. To get a full picture of proposed PUAM topology, the performances between PUAM and conventional models are compared by finite-element analysis (FEA), including the no-load back-EMF, torque, power factor, losses, efficiency, and flux weakening capability. Finally, a prototype was manufactured and tested to validate the FEA and theoretical analysis, which has a good agreement. This article aims to provide an alternative of topology for direct-drive application.

The bearing currents of alternating current motors are a common issue in the field of variable-frequency drives. When the bearing voltage exceeds the breakdown threshold of the oil film, the parasitic capacitance network of motor system components provides a pathway for leakage currents, ultimately endangering the metal ball bearings. It should be noted that the capacitance from the end winding to the rotor makes a significant contribution to the parasitic capacitance network. Therefore, a more detailed analytical model that considers the impact of the end winding is needed, but existing analytical models are not yet capable of achieving this. This paper establishes a detailed finite element model of the electric motor, focusing on the impact factors of variation of the proportion of the end winding to rotor capacitance (Cwr,ew). Additionally, in this paper, the calculation formula for the capacitance in the equivalent circuit of the flat-wire motors is modeled. Building upon previous research, simplified analytical models for two types of bearing currents are established and verified through simulation, with the simulation results being essentially consistent with the analytical outcomes. Finally, the paper summarizes the impact of circulating bearing currents and EDM bearing currents on bearing electro-corrosion and calculates the electrical life of the motor bearings.

A novel distributed magnetic pole permanent magnet planetary machine (DMPPMPM) is proposed in this article, which has the advantages of high power density, high integration, reliable transmission, and simple controllability. The proposed DMPPMPM is composed of several eccentric permanent magnet (PM) rotors. Planetary gears are connected with PM rotors and meshed with a sun gear to output a larger torque. An analytical magnetic field prediction model is established by the magnetic circuit and bilinear conformal transformation to illustrate the airgap flux density, back electromotive force (EMF) and electromagnetic torque. Furthermore, the symmetric DMPPMPM is parameterized and discussed, while the harmonic components of airgap flux density, back EMF, and torque are simplified to yield some designing instructions of the machine theoretically. Besides, the symmetric and sequence conditions are found to improve the quality of back EMF and torque. Finite element analysis and prototype experiment verify the proposed structure and instructions.

This article investigates the power factor characteristic in spoke-type permanent magnet Vernier motors (ST-PMVMs) with different slot–pole combinations for in-wheel direct drive. First, the working principle and power factor expression have been presented, and the influencing factors of the power factor have been targeted. Second, the relationship of slot and pole numbers is illustrated, and the general slot–pole combinations of PMVM with less armature magnetomotive force (MMF) harmonics have been derived and concluded. Then, the armature MMF harmonics, armature reaction magnetic field, and armature reaction reactance components under different slot–pole combinations are illustrated and compared, where a parameter to evaluate the ratio of useless leakage harmonic reactance is introduced. Next, the performances, such as the back EMF, armature reaction magnetic field, $d$ - and $q$ -axis inductances, output torque capability, and power factor, are all analyzed. Finally, a prototype was manufactured, and the experimental results match well with the theoretical and FEA results.

Nowadays, in-wheel drive mode is considered as one of the most promising modes for electric vehicles (EVs). The motor type plays a significant role in the vehicle performances. This article focuses on the performance between permanent magnet synchronous motor (PMSM) and permanent magnet Vernier motor (PMVM) for in-wheel direct drive. First, the required performances are determined by the vehicle requirements. The prototypes of PMVM and PMSM are manufactured after the comparison. Then, the expressions of air-gap magnetic field harmonic, electromagnetic torque, and power factor are theoretically derived, where the parameter torque ratio is introduced to evaluate the torque ratio between PMVM and PMSM. Based on experiment, the back-electromotive force harmonics, cogging torque, maximum torque per ampere capability, flux-weakening capability, torque, efficiency, and power factor are compared and analyzed. Subsequently, the discussions are carried out, where the strength and weakness of two-type motors for in-wheel drive are concluded and the future prospects are suggested. Finally, the conclusions of two-type in-wheel motors are then extracted. This article aims at providing a reference for the exploration of alternating in-wheel motor types, which can promote the development of high-performance in-wheel drive system for EVs.

High torque density permanent magnet synchronous motors (PMSM) are widely used in aerospace and vehicles. Nevertheless, due to high torque density, high heat generation increases the temperature of the motor, which may damage the motor in severe cases. Therefore, the heat dissipation problem is important research topic of high torque density motor. In this paper, a high torque density PMSM is designed. The cooling form of PMSM that heat pipe inserted into the stator slot is first determined. Based on this, the electromagnetic design scheme of the motor is designed. In addition, the high heat dissipation capacity of the heat pipe is verified according to comparing the cooling effects of two methods: natural cooling and heat pipe cooling.