Search Results (107)

Auxiliary teeth are usually used in fractional-slot concentrated winding (FSCW) machines for fault tolerance. However, the influence of auxiliary teeth on torque and electromagnetic vibration performance differs with different slot–pole configurations. Thus, this paper investigates electromagnetic vibration and mitigation methods in FSCW permanent magnet (PM) machines with auxiliary teeth. The relationship between yoke forces and tooth parameters of two dual three-phase (DTP) FSCW-PM machines with 12-slot/14-pole configuration and 12-slot/10-pole configuration is studied and compared. Results reveal that (1) the 2p-order airgap electromagnetic force reduces second-order yoke force in the 12-slot/14-pole machine but increases it in the 12-slot/10-pole machine. (2) Through optimized tooth width, slot harmonics can be mitigated, but the fundamental winding magnetic field in the 12-slot/10-pole machine is also weakened, whereas the 12-slot/14-pole machine achieves fundamental field preservation or enhancement. Based on these findings, auxiliary tooth optimization and rotor pole profile shaping are proposed for vibration reduction in 12-slot/14-pole machine. Electromagnetic–mechanical coupled simulations conducted in ANSYS Maxwell/Workbench 2023 demonstrate that the optimized design reduces the cogging torque peak from 11.4 mN·m to 2.9 mN·m (74.6% reduction), suppresses housing surface vibration acceleration by 21%, and maintains the average output torque without reduction. Full article

The ironless tubular permanent magnet synchronous linear motor (TPMSLM) is in high demand for high-precision servo control applications due to its advantages of having zero cogging effect and high dynamic response. However, its electromagnetic field analysis model has not yet been perfected. This paper aims to accurately predict the magnetic field distribution and electromagnetic performance parameters of an ironless TPMSLM. Taking the axially magnetized ironless TPMSLM as an example, and disregarding the influence of the armature magnetic field on the air gap magnetic field, a simplified analytical model of the TPMSLM is established in the cylindrical coordinate system based on the equivalent magnetization current method (EMC), and the analytical formula for the air gap magnetic flux density is then derived. Subsequently, by applying electromagnetic field theory and the analytical formula for the magnetic flux density in the air gap, analytical expressions for the back electromotive force (back EMF) and thrust are derived, reducing analytical complexity while maintaining accuracy. The accuracy and practicality of the proposed analytical formulas are validated through comparisons with finite element analysis (FEA) and experimental prototypes. This analytical approach facilitates the optimization of linear motor parameters and the study of thrust fluctuation suppression, thereby laying the foundation for high-precision servo control of linear motors. Full article

Axial flux permanent magnet (AFPM) machines offer some advantages over conventional radial flux machines for the case of a limited space in the axial direction, such as high torque density, compact structure, and modular design ability. They, therefore, are increasingly used in wind power and electrical vehicles. This paper focuses on developing an effective analytical model and equivalent auto-finite element method (FEM), including rotor linear motion for the design of axial flux permanent magnet generators in vertical axis wind turbines. The initial design of a 1.35 kW-AFPM generator with an outer double rotor and double layer concentrated windings is based on analytical equations, and then it is refined using equivalent time-stepping transient FEM, including rotor linear motion to calculate voltage, electromagnetic force, and torque. The automatic generation of an equivalent transient 2D-FEM model to replace a time-consuming 3D-FEM model is investigated. As a consequence, the influence of slotting the effect on a 1.35 kW-AFPM machine’s performances, such as air gap flux density, internal voltage, and cogging torque, is announced. Full article

The genus Microbulbifer comprises a group of marine, gram-negative bacteria known for their remarkable ability to adapt to a variety of environments. Therefore, this study aimed to investigate the genetic diversity and metabolic characteristics of M. spongiae MI-G^T and three Microbulbifer reference strains by genomic and comparative genomic analysis. Compared to free-living reference strains, the lower GC content, higher number of strain-specific genes, pseudogenes, unique paralogs, dispensable genes, and mobile gene elements (MGEs) such as genomic islands (GIs) and insertion sequence (IS) elements, while the least number of CAZymes, indicates that M. spongiae MI-G^T may be a facultative sponge-symbiont. Comparative genomic analysis indicates that M. spongiae MI-G^T possesses a plasmid and a higher number of strain-specific genes than Microbulbifer reference strains, showing that M. spongiae MI-G^T may have acquired unique genes to adapt sponge-host environment. Moreover, there are differences in the functional distribution of genes belonging to different COG-classes in four Microbulbifer strains. COG-functional analysis reveals a lower number of strain-specific genes associated with metabolism, energy production, and motility in M. spongiae MI-G^T compared to Microbulbifer reference strains, suggesting that sponge-associated lifestyle may force this bacterium to acquire nutrients from the sponge host and loss motility genes. Finally, we found that several proteins associated with oxidative stress response (sodC, katA, catA, bcp, trmH, cspA), osmotic stress response (dsbG, ampG, amiD_2, czcA, czcB, and corA), and tolerance to biotoxic metal proteins (dsbG, ampG, amiD_2, czcA, czcB, and corA) are absent in M. spongiae MI-G^T but present in Microbulbifer reference strains, indicating that M. spongiae MI-G^T live in a stable and less stress environment provided by the sponge host than free-living Microbulbifer strains. Our results suggest M. spongiae MI-G^T exhibits gene characteristics related to its adaptation to the sponge host habitat, meanwhile reflecting its evolution towards a sponge-associated lifestyle. Full article

The force ripple of a permanent magnet synchronous linear motor (PMSLM) caused by multi-source disturbances in practical applications seriously restricts its high-precision motion control performance. The traditional single-mechanism model has difficulty fully characterizing the nonlinear disturbance factors, while the data-driven method has real-time limitations. Therefore, this paper proposes a hybrid modeling framework that integrates the physical mechanism and measured data and realizes the dynamic compensation of the force ripple by constructing a collaborative suppression algorithm. At the mechanistic level, based on electromagnetic field theory and the virtual displacement principle, an analytical model of the core disturbance terms such as the cogging effect and the end effect is established. At the data level, the acceleration sensor is used to collect the dynamic response signal in real time, and the data-driven ripple residual model is constructed by combining frequency domain analysis and parameter fitting. In order to verify the effectiveness of the algorithm, a hardware and software experimental platform including a multi-core processor, high-precision current loop controller, real-time data acquisition module, and motion control unit is built to realize the online calculation and closed-loop injection of the hybrid compensation current. Experiments show that the hybrid framework effectively compensates the unmodeled disturbance through the data model while maintaining the physical interpretability of the mechanistic model, which provides a new idea for motor performance optimization under complex working conditions. Full article

Pelvic organ prolapse (POP) is a prevalent condition, affecting women all over the world, and is commonly treated through surgical interventions that present limitations such as recurrence or complications associated with synthetic meshes. In this study, biodegradable poly($ϵ$-caprolactone) (PCL) cog threads are proposed as a minimally invasive alternative for vaginal wall reinforcement. A custom cutting tool was developed to fabricate threads with varying barb angles (90°, 75°, 60°, and 45°), which were produced via Melt Electrowriting. Their mechanical behavior was assessed through uniaxial tensile tests and validated using finite element simulations. The results showed that barb orientation had minimal influence on tensile performance. In simulations of anterior vaginal wall deformation under cough pressure, all cog thread configurations significantly reduced displacement in the damaged tissue model, achieving values comparable to or even lower than those of healthy tissue. A ball burst simulation using an anatomically accurate model further demonstrated a 13% increase in reaction force with cog thread reinforcement. Despite fabrication limitations, this study supports the biomechanical potential of 3D-printed PCL cog threads for POP treatment, and lays the groundwork for future in vivo validation. Full article

This paper proposes a harmonic screening-based method for calculating the cogging torque of the axial flux permanent magnet synchronous motor. The magnetic field energy in the air gap is derived from the air gap flux and the magnetomotive force of rotor. The cogging torque is then obtained using the energy-based method. Compared with finite element analysis, the proposed approach is significantly faster while maintaining high accuracy. It is particularly effective for scenarios involving stator staggering, which can facilitate quick calculation of cogging torques of many different staggering angles, offering rapid insights into motor performance during the initial design. The method achieves a similarity accuracy with FEA results and reduces computation time, demonstrating both its efficiency and reliability. Full article

Surface-mounted permanent magnet synchronous generators (SPMSGs) are well suited for wind power applications mainly because of their high power density, low cogging torque, and effective thermal management. This study proposes an eccentric Halbach PM array pole shape to enhance the power generation capability of SPMSGs specifically designed for low-speed wind power generation. The topology of the proposed eccentric Halbach PM arrangement is optimized using a genetic algorithm. Two-dimensional finite element simulations indicate that the eccentric Halbach configuration significantly improves flux focusing and magnetic field distribution. Compared to the conventional design, the proposed structure exhibits a substantial increase in electromotive force with reduced total harmonic distortion. Cogging torque is reduced by 48.6%, supporting improved starting and low-speed operation. Under on-load, the proposed design delivers higher average torque with reduced ripple, contributing to smoother operation. At a rated speed, the output power increases by 25%, with consistently higher power generation capability across a wide range of load conditions. Additionally, the proposed generator achieves higher efficiency across all operating speeds. These findings confirm the effectiveness of the eccentric Halbach array configuration in improving the power generation capability of SPMSG, thereby reinforcing its applicability to low-speed wind energy systems aligned with long-term sustainability objectives. Full article

Objectives: Assessing balance in highly trained individuals, such as military pilots, poses challenges, as deficits may be underestimated when compared to general population norms. To address this, several studies have proposed tailored databases providing reference values for specific populations. This study retrospectively analyzed balance characteristics in active-duty military pilots of the Italian Air Force. Methods: We enrolled 106 subjects split into two groups: 53 military pilots from the Italian Air Force and 53 civilians without flight experience or exposure to specific vestibular stimuli. All participants underwent ENT examinations with audiometric testing to exclude related pathologies, followed by a personal history collection. Subsequently, they completed the EquiTest protocol across six standard conditions. Results: Significant differences were observed between Army Aviators and Non-Aviators. The PREF variable showed the most consistent distinction, with military pilots demonstrating a superior performance (p < 0.01). Additionally, borderline differences were noted in Condition 6 of the equilibrium scores (p = 0.056), and in the Centre of Gravity (COG) analysis along the X-axis for Conditions 1 and 5 (p = 0.090), and for Condition 2 (p = 0.050). These findings suggest enhanced postural control strategies among Army Aviators under conditions of sensory conflict. Conclusions: These findings suggest that normative balance values specific to military pilots should be used when evaluating aviators recovering from balance deficits. Such tailored benchmarks can help determine the need for rehabilitation before returning to duty, ensuring optimal performance under demanding conditions. Further research is necessary to explore the underlying mechanisms responsible for these adaptations and to identify the specific stimuli that contribute to the enhanced balance capabilities observed in this highly trained population. Full article

In this paper, the concept of symmetry is utilized to optimize the structural parameters and output characteristics of the generator design—that is, the construction and solution of the equivalent magnetic circuit method for the hybrid excitation generator are symmetrical. To address the issues of high excitation loss and low power density in purely electrically excited generators, as well as the difficulty in adjusting the magnetic field in purely permanent magnet generators, a new topology for a built-in permanent magnet and salient-pole electromagnetic hybrid excitation generator is proposed. Firstly, an equivalent magnetic circuit model of the generator is established. Secondly, expressions are derived to describe the relationships between the dimensions of the salient-pole rotor and the permanent magnets and the generator’s no-load induced electromotive force, cogging torque, and air gap flux density. These expressions are then used to analyze the structural parameters that influence the generator’s performance. Thirdly, optimization targets are selected through sensitivity analysis, with the no-load induced electromotive force, cogging torque, and air gap flux density serving as the optimization objectives. A multi-objective genetic algorithm is employed to optimize these parameters and determine the optimal structural matching parameters for the generator. As a result, the optimized no-load induced electromotive force increased from 18.96 V to 20.14 V, representing a 6.22% improvement; the cogging torque decreased from 177.08 mN·m to 90.52 mN·m, a 48.88% reduction; the air gap flux density increased from 0.789 T to 0.829 T, a 5.07% improvement; and the air gap flux density waveform distortion rate decreased from 6.22% to 2.38%, a 39.3% reduction. Finally, a prototype is fabricated and experimentally tested, validating the accuracy of the simulation analysis, the feasibility of the optimization method, and the rationality of the generator design. Therefore, the proposed topology and optimization method can effectively enhance the output performance of the generator, providing a valuable theoretical reference for the design of hybrid excitation generators for vehicles. Full article

A PCB stator axial flux permanent magnet (AFPM) motor is presented that overcomes the manufacturing challenges associated with the complex geometry of conventional stators by employing a PCB substrate. Traditionally, AFPM motors are produced by winding coils around the stator teeth, a process that requires specialized winding machinery and is both labor intensive and time consuming, ultimately incurring considerable manufacturing costs and delays. In contrast, PCB substrates offer significant advantages in manufacturability and mass production, effectively resolving these issues. Furthermore, the primary material used in PCB substrates, FR-4, exhibits a permeability similar to that of air, resulting in negligible electromagnetic cogging torque. Cogging torque arises from the attraction between permanent magnets and stator teeth, creating forces that interfere with motor rotation and generate unwanted vibration, noise, and potential mechanical collisions between the rotor and stator. In the PCB stator design, the conventional PCB circuit pattern is replaced by the motor’s coil configuration, and the absence of stator teeth eliminates these interference issues. Consequently, a slotless motor configuration with minimal vibration and noise is achieved. The PCB AFPM motor has been applied to a vehicle-mounted electric water pump (EWP), where mass production and space efficiency are critical. In an EWP, which integrates the impeller with the motor, it is essential that vibrations are minimized since excessive vibration could compromise impeller operation and, due to fluid resistance, require high power input. Moreover, the AFPM configuration facilitates higher torque generation compared to a conventional radial flux permanent magnet synchronous motor (RFPM). In a slotless AFPM motor, the absence of stator teeth prevents core flux saturation, thereby further enhancing torque performance. AC losses occur in the conductors as a result of the magnetic flux produced by the permanent magnets, and similar losses arise within the PCB circuits. Therefore, an optimized PCB circuit design is essential to reduce these losses. The Constant Trace Conductor (CTC) PCB circuit design process is proposed as a viable solution to mitigate AC losses. A 3D finite element analysis (3D FEA) model was developed, analyzed, fabricated, and validated to verify the proposed solution. Full article

Background/Objectives: The population of Japan has a high life expectancy, but there is room for improvement in terms of the country’s healthy life expectancy. The long period of care dependency among Japan’s elderly is also a major economic health challenge. Dementia is a major factor in the need for care, and its prevention is a crucial and urgent challenge. There are recent reports of a possible association between changes in oral function and cognitive impairment, but the details of this association remain unclear. To clarify the relationship between poor oral function and cognitive impairment, we conducted an exploratory investigation using a cognitive function assessment (Mini-Cog) administered in a large-scale study and its relevance to oral function. Methods: The study population was 678 community-dwelling individuals aged ≥65 years living in Tarumizu city, Japan, in 2019. Cognitive function was assessed using the Mini-Cog test, and the oral survey was a modification of the content of the Oral Hypofunction Examination as defined by the Japanese Society of Gerodontology. Results: The participants’ median age was 73 years. The oral function results revealed median scores below the oral hypofunction criterion for occlusal force, tongue pressure, oral diadochokinesis, and swallowing function. The results of a binomial logistic regression analysis indicated that tongue–lip motor function was independently associated with oral function in relation to cognitive impairment. Conclusions: The oral function associated with cognitive impairment in this study was tongue–lip motor function. Aiming to improve this function may prevent the exacerbation of cognitive impairment. Full article

In this article, we propose, for the first time, to apply the flux-switching permanent magnet (OR-FSPM) generator to the oscillating water column wave energy conversion (OWC-WEC), and a novel dual three-phase 24-slot/46-pole OR-FSPM generator for OWC-WEC is designed and analyzed. The feasible phase-shift angle (PH-Angle) between the two sets of windings, namely 0°, 30° and 60°, is analyzed. The electromagnetic performance of the generator under three winding configurations is investigated, including PM flux linkage, back electromotive force (EMF), open-circuit rectified voltage, inductance, cogging torque, electromagnetic torque and unbalanced magnetic force (UMF). The prototype is manufactured, and the experimental results are consistent with that of the finite-element analysis (FEA) results. The generator with 0° and 60° PH-Angle winding configuration has stronger fault tolerance. When the 30° PH-Angle winding configuration is adopted, it has the maximum back-EMF fundamental amplitude, maximum average electromagnetic torque and the minimum torque ripple, and there is no UMF when a single set of windings is running. Therefore, the proposed novel OR-FSPM generator with 30° PH-Angle winding configuration is more suitable for OWC-WEC. Full article

Nowadays, Permanent Magnet Synchronous Linear Motors (PMLSMs) are widely applied as direct drive mechanisms in the industrial manufacturing sector, which can fulfill the requirements for high precision and high production rates. However, PMLSMs are characterized by significant thrust ripple issues, including cogging force, ripple force, and end force, which severely deteriorate the operational accuracy. This paper provides a review of analysis and suppression of the thrust ripple characteristics in PMLSM, aiming to offer guidance on how to mitigate the thrust ripples, and hence, enhancing the operational accuracy of PMLSM system. Firstly, the structural features and operating principles of PMLSMs are analyzed to understand the causes of thrust ripples. Then, strategies for mitigating the PMLSM thrust ripples are elaborated upon, respectively, from two main perspectives: structural optimization and control strategies. Finally, a summary and outlook are presented. Full article

With the recent proliferation of electric vehicles, there is increasing attention on drive motors that are powerful and efficient, with a higher power density. To meet such high power density requirements, the cooling technology used for drive motors is particularly important. To further optimize the cooling effects, the use of direct oil-cooling technology for drive motors is gaining more attention, especially regarding the requirements for electric vehicle electric oil pumps (EOPs) in motor cooling. In such high-temperature environments, it is also necessary for the EOP to maintain its performance under high temperatures. This research explores the feasibility of using high-temperature-resistant ferrite magnets in the rotors of EOPs. For a 150 W EOP motor with the same stator size, three different rotor configurations are proposed: a surface permanent magnet (SPM) rotor, an interior permanent magnet (IPM) rotor, and a spoke-type IPM rotor. While the rotor sizes are the same, to maximize the power density while meeting the rotor’s mechanical strength requirements, the different rotor configurations make the most use of ferrite magnets (weighing 58 g, 51.8 g, and 46.3 g, respectively). Finite element analysis (FEA) was used to compare the performance of these models with that of the basic rotor design, considering factors such as the no-load back electromotive force, no-load voltage harmonics (<10%), cogging torque (<0.1 Nm), load torque, motor loss, and efficiency (>80%). Additionally, a comprehensive analysis of the system efficiency and energy loss was conducted based on hypothetical electric vehicle traction motor parameters. Finally, by manufacturing a prototype motor and conducting experiments, the effectiveness and superiority of the finite element method (FEM) design results were confirmed. Full article