Pole Shape Research Articles

Analytical Investigation of the Air Gap Flux Density of Surface-Mounted PMSMs With Irregular Pole Shapes

Analytical Investigation of the Air Gap Flux Density of Surface-Mounted PMSMs With Irregular Pole Shapes

Relationship between the morphology of the posterior pole of the eyeball and changes in choroidal structure and blood flow in myopia.

The eyeball axial length (AL) is an important biological indicator of myopia, which has been widely studied. However, little research has been conducted on the relationship between eye shape and fundus structural changes in myopia. This study aimed to analyze the relationship between the shape of the posterior pole of the eye, and choroidal characteristics by comparing with the relationship between AL and choroidal characteristics. And to investigate the clinical significance of the shape of the posterior pole in the pathophysiological changes related to myopia. In this study, the data of 147 eyes (22 emmetropic and 125 myopic) of participants aged 20-30 years, examined in 2021, were collected. Optical coherence tomography (OCT) was used to analyze the posterior-pole images, choroidal thickness (ChT), choroidal vascular volume (CVV), and three-dimensional choroidal vascular index (3DCVI). The least squares method was used to fit the ellipse that was most consistent with the actual shape of the posterior pole. Multiple stepwise regression analysis was used to investigate the relationships between the fitting posterior-pole vertex curvature (fPVC), and ChT, CVV, and 3DCVI. The mean AL of the participants was 25.15±1.35 mm (22.30-27.92 mm), the mean spherical equivalent was -3.59±2.62 D (+0.5 to -11.75 D), and the mean fPVC was 0.158±0.036 mm-1. The fPVC was positively correlated with the AL (r=0.639, P<0.001)and negatively correlated with the spherical equivalent (r=-0.666, P<0.001). The AL and fPVC were independently negatively correlated with the ChT and CVV in the macular region (0-6 mm). In the peripheral area (6-9 mm), the fPVC (ChT: β=-0.529, P<0.001; CVV: β=-0.441, P<0.001) was more closely associated with the ChT and CVV than the AL (ChT: β=-0.140, P=0.127; CVV: β=-0.127, P=0.190). The 3DCVI may be nonlinearly correlated with the AL and fPVC, and the relationship curve between the fPVC and 3DCVI was clearer than that between the AL and 3DCVI. In addition to the AL, the shape of the posterior pole is related to the ChT and choroidal vascular changes, and more closely related to the peripheral choroid than AL. Our findings provide another perspective for the prevention and monitoring of myopic-related pathological changes in clinical practice.

The Ndalem Wuryaningrat Hall of Pillars in Aesthetic Studies

The Ndalem Wuryaningrat is a Javanese noble heritage building with Javanese cultural significance designed exclusively for noble descendants. This research aims to show four main pillars in Javanese building known as soko guru. Not only does the soko guru pole serve as a foundation, but it also represents Javanese cultural values. This research method is ethnographic, which examines meaning through direct observation and interviews with sources. The results of this study are the meaning behind the hierarchy of soko guru in The Ndalem Wuryaningrat. Each element's meaning is strongly tied to Javanese cultural notions and reflects its owner. Even though it changed shape throughout the preservation of the Ndalem Wuryaningrat building, the shape of the soko guru pillar at Ndalem Wuryaningrat remains intact and has Javanese cultural significance. This study discovered that the soko guru pole symbolizes Javanese culture and the owner's position through the pole system, shape, and pattern. The conclusion of this research is soko guru pole represents Javanese culture and is associated with the Javanese people's belief in Islam through the soko guru pole features meaningful columns, motifs, and embellishments.

A study of rare-earth magnet profiles for torque ripple improvement of axial flux permanent magnet machine

Purpose The purpose of this study is to reduce the cogging torque in axial flux permanent magnet (AFPM) machine using optimal magnet shape. Design/methodology/approach This study analyzes different magnet shapes for AFPM machine performance enhancement. Three-dimensional (3D) finite element analysis is performed to see the effects of pole shaping on the cogging torque of the AFPM machine. Findings The magnetic pole shape has a significant effect on cogging torque and overall efficiency. The conventional model has the highest torque whereas the conventional skewing affected cogging torque positively and significantly reduced the cogging torque. The combination of skewing the pole along with face curving is more effective and decreases the cogging torque from 3.88 Nm to 1.5 Nm. Originality/value Rare-earth magnets are the most expensive and important part of AFPM machines. Shape and volume optimization of rare-earth magnets is crucial for the performance of AFPM machines. The research aims to analyze the different permanent magnet designs for performance improvement of the AFPM machine. Conventional flat top trapezoidal, curved-top and skewed-magnet shapes are analyzed and the performance of the AFPM machine is compared with different magnet shapes. Curved-top shape and skewed magnet significantly reduce the cogging torque. Furthermore, a combination of curved-top shape and skew magnet shape is proposed to reduce the cogging torque further and improve the AFPM machine’s overall performance. Newly proposed magnet profile gives skewed curve magnet shapes which reduce the cogging torque further. 3D finite element analysis has been used to analyze the single-sided AFPM with all four different magnet shapes. The research focuses on single-sided AFPM machines, but the results are also valid for double-sided AFPM machines and can be extended to other topologies of AFPM machines.

Rotor pole and stator tooth shaping in FSPM machines for torque performance optimization

Purpose This study aims to obtain the minimum torque ripple at the maximum average torque for Flux-switching permanent magnet (FSPM) machines. Design/methodology/approach This paper is about torque performance optimization of the FSPM machines. To achieve that, finite element analysis and genetic algorithm (GA) are used. Five different designs are simulated, optimized and compared on their air gap flux density, back electromotive force, cogging torque, average torque, torque density and torque ripple. Findings After the thousands of iterations, its proved that all proposed shaping techniques have potential for reducing torque ripple and cogging torque, with slightly reduced average torque. The best design is the joint stator and rotor shaping, Design V, which results in the lowest torque ripple and cogging torque. The techniques should be applicable to FSPMs with other stator slot/rotor pole number combinations. Originality/value In this paper, rotor pole shaping by notching, chamfering and generic shaping, stator tooth shaping and joint shaping techniques are investigated for 12 s/10p FSPM machines. Rotor and stator flanks are optimized separately and jointly, by using finite element analysis and GA for optimization to achieve maximum average torque and minimum torque ripple. Five different design is implemented and compared, respectively.

Cogging Torque Reduction of Brushless DC Motor: Investigating the Efficacy of Ra-dial Pole Shaping Technique with Novel Bump-Shaped Rotor Pole

With the rising demand for high-performance motors in electrical vehicle applications, permanent magnet brushless DC motors are a promising solution due to their various attractive features. However, it has a significant drawback of high cogging torque, which deteriorates the overall motor performance. This negative impact is dominating in electric vehicles for low-speed applications. It is desirable to reduce the cogging torque to improve the performance of the radial flux brushless DC motor. The prime focus of this research is reducing cogging torque through the radial pole shaping technique with a bump-shaped rotor pole surface. This work also investigates the impact of the proposed approach on torque ripple and motor performance while cutting down the requirement for rare earth material. This paper uses two ratings: 1000 W, 510 rpm, and 250 W, 150 rpm motors. Two reference motors of proposed ratings were designed using radial-shaped permanent magnet poles. Finite element software is used for the simulation and modeling of the motors. A novel bump-shaped permanent magnet pole shape is introduced, and in-depth investigations have been carried out to evaluate the impact of the proposed pole shape on cogging torque. The validity of the analysis results is further substantiated by comparing the improved and reference model results. The comparison investigation indicates that the motor equipped with the proposed pole shape performs better than the reference motor.

Control Techniques of the Modified Stator and Rotor Pole Shape in a 6/4 Switched Reluctance Motor: Effects on Torque Ripple Minimization

A switched reluctance motor (SRM) provides the advantages of simple and robust motor structure. But in switched reluctance motors (SRMs), as the result of the double ridged structure of motor, the torque vibrations and acoustic noise are relatively higher as against the sinusoidal machines. This study intends to minimize the torque ripple of a SRM. In machine’s design, new control approaches were employed by modifying the stator and rotor pole shapes in order to minimize the torque ripple in SRM. Moreover, by observing the performance of 6/4 SRM under steady-state conditions and at constant dwell angles for fan load, torque ripple (TR) analyses were performed. The driver was simulated for current control (CC), and control of sum of squared phase currents (SPC). Fuzzy Logic Controller (FLC) was also applied on speed loop in order to minimize torque ripple, and to improve the effective torque. In MATLAB/SIMULINK environment, the results are being discussed in detail. The FLC technique provided successful results in improving the effective torque ripple of SRM. The results of simulation were verified by the experimental results.

INFLUENCE OF THE POLES SHAPE OF DC ELECTROMAGNETIC ACTUATOR ON ITS THRUST CHARACTERISTIC

Many technical objects use the electromagnetic DC actuators, which, unlike AC actuators, are more reliable, simpler in terms of manufacturing technology and have greater wear resistance. The listed advantages are the reason for the significant use of DC actuators in various industries including application as drive mechanisms of electrical devices. The DC actuator as a part of any technical object almost always plays one of the main roles from the point of view of reliable operation of entire device. Therefore the question of studying the designs of actuators and their characteristics is a rather topical task. Three designs of forward-moving electromagnetic DC actuators with the same overall dimensions and winding data are studied. They differ in the shapes of the supporting surfaces of poles, in other words, the surfaces with flat, conical and cut-conical shapes. As established, the shape of the supporting surfaces of poles has a significant impact on the thrust characteristics of the actuator and depending on the length of air gap this effect has a different character. The patterns of magnetic field of the studied actuators with an attracted armature are constructed, and the nature of magnetic field distribution and magnetic flux density distribution in operated gap are evaluated. The nature of the influence of cutting angle on static thrust characteristic for actuators with conical and cut-conical pole shapes is studied too. References 21, table 1, figures 7.

Abstract 14382: Discovery of Magnetocardiography for Monitoring of Myocardial Injury Following Radiotherapy: A Case Report

Introduction: Radiotherapy, as one of the important management approaches for cancer, could induce the cardiomyocyte injury and increase the risk for cardiovascular diseases. However, early detection and identification of myocardial damage during radiotherapy is still challenging with routine methods. Magnetocardiography (MCG), a novel way to detect feeble magnetic fields formed by electrical activity of cardiomyocytes, is highly sensitive to the diagnosis of myocardial ischemia. Here, we present a case for whom the MCG changes observed during radiotherapy for thymoma. Case: The patient received radiotherapy for the tumor bed in the second month after transthoracoscope enlarged thymectomy and resection of the adherent tissues, with a total radiation dose of 50Gy/20F. The mean heart dose was 20.62Gy, and the volume of heart receiving greater than or equal to 30Gy is 31.77%. Comprehensive clinical biochemistry, ECG and echocardiography were taken before radiotherapy and presented without any abnormalities in cardiac structure and function. The magnetic field angle, character of positive and negative pole at T peak were also normal in magnetic field map before radiotherapy(Figure 1A). MCG and ECG were collected every week during radiotherapy. Nevertheless, during the whole 4 weeks, no significant abnormalities were found but the shape of positive and negative pole in magnetic field map became distorted gradually compared with the initial standard ellipse in MCG(Figure1B-D). Recurrent chest pain influenced the patient in the last two weeks either, which indicates the possibility of myocardial injury. Conclusions: Our case showed the possible minimal myocardial injury detected by MCG in the early stage of radiotherapy, while ECG is normal throughout the therapy. Therefore, our case may provide interesting insights into the potential of MCG for early detection of radiotherapy-induced myocardial damage, which deserves further validation study in the future.

Design and Cogging Torque Reduction of Radial Flux Brushless DC Motors with Varied Permanent Magnet Pole Shapes for Electric Vehicle Application

Brushless direct current motors have more attractive features, making them a promising solution for electric vehicle applications. A 1 kW, 510 rpm, 24-slots and 8-pole inner runner type surface permanent magnet mounted radial flux brushless DC motor with seven different permanent magnet pole shape rotor is investigated. Motors with different permanent magnet shape rotors were designed, and finite element modelling and simulation were carried out. For performance comparison, the initial design with a radial-type pole shape was regarded as a reference design. Cogging torque is detrimental to the overall performance of the motor, typically in low-speed applications like electric vehicles. The primary aim of this paper is to reduce the cogging torque &amp; study its effect on the overall performance of the motor and minimize torque ripples with reduced permanent magnet requirements. The proposed designs are analyzed in terms of cogging torque, flux density, torque, efficiency, flux linkage and back-EMF. The comparative analysis shows that the motor with bump-shaped permanent magnet rotor poles has betterperformance than the others.

Design Optimization of Combined Function Accelerator Magnet Using Truncated Singular Value Decomposition

The Japan Proton Accelerator Research Complex (J-PARC) is a world-class accelerator facility for particle and nuclear physics experiments such as the rare kaon decays experiment (KOTO), the T2K long-baseline neutrino experiment, and future projects such as COMET. A new stretcher ring (SR) comprising a combined function superconducting magnet is proposed to run all of the facilities at the same time, which can improve beam efficiency and increase operating time. In order to achieve the field quality requirements on the magnet aperture, it is critical to identify an optimum pole shape. Dipole, quadrupole, and sextupole fields are required for the combined function magnet. To find the best design parameters for this analysis, we employed singular value decomposition. The singular value decomposition (SVD) technique resulted in a solution to the desired parameters and a quick process to obtain a 2D pole profile.

Modelling and Design of Habitat Features: Will Manufactured Poles Replace Living Trees as Perch Sites for Birds?

The need to support life in degraded landscapes is a pressing challenge of our time. Models from ecology, computing, architecture, and engineering can support the design and construction of habitat features in contexts where human intervention is necessary and urgent. For example, anthropogenic change is causing many arboreal habitats to disappear due to diminishing populations of large old trees. Current management approaches can provide artificial replacements in the shape of poles for perching and boxes for nesting. However, their large-scale long-term impacts are rarely assessed and often unclear. Along with benefits, these structures can result in ecological traps, waste, and pollution. Although computer-aided design and fabrication can provide more sophisticated solutions, limited understanding of tree structures and their use by arboreal wildlife constrain the formulation of clear goals for engineering. In response, this research examines long-term implications at a restoration site that already features a variety of living and manufactured habitat structures. To do so, we build a computational simulation that uses high-fidelity lidar scans of trees in combination with field observations of bird interactions with branches. This simulation models landscape-scale dynamics of habitat supply over hundreds of years. It can account for many types of structures, including trees, snags, and utility poles, irrespective of the processes that led to their availability. We use this understanding of integrated supply to generate quantitative comparisons of design strategies that can inform design decisions in application to arboreal habitats and other modified ecosystems.

Pole shape design of ring winding axial flux permanent magnet used in a direct‐drive electric boat for cost‐efficient cogging torque alleviation

AbstractThe recently introduced Ring Winding Axial Flux Permanent magnet Motor (RW‐AFPM) is inspired by the yokeless structure of Yokeless and Segmented Armature (YASA) AFPMs and the partitioned‐phases configuration of transverse flux motors. Its potential application for rim‐driven electric ships propulsion has been examined in the previous studies and, here, it will be studied for ultra‐light direct‐drive electric boats. Owing to their specific structural features, the relatively large cogging torque of RW‐AFPMs seems to be a significant challenge for such applications. On the other hand, as investigated in previous studies, cogging torque reduction methods, such as conventional skewing, seem unsuitable for this type of machine. Thus, this paper will address the cogging torque issue via a comprehensive pole shape analysis. The results will be useful for all kinds of partitioned‐phases topologies that have high specific torque capability but suffer from large cogging effects. All analyses are performed via 3D‐FE models, the accuracy of which is pre‐verified through experiments.

Overview of Key Technologies for Torque Ripple Suppression in Four- Wheel In-Wheel Motor Drive Electric Vehicles

Aims and Objectives: The stability control of the four-wheel hub motor-driven electric vehicle is of great significance to the safety of the driver during the driving process, and the torque fluctuation is an important factor that affects the stability control of the vehicle. Therefore, this paper reviews the key technologies and difficulties of torque ripple suppression for in-wheel motor-driven electric vehicles from two aspects: rational design of the in-wheel motor structure to suppress the torque fluctuation of the motor and the in-wheel motor torque control distribution strategy. Methods: Through the analysis of the structural characteristics of the motor, the structural optimization design of the pole slot, cogging, core shape, and magnetic pole shape is used to suppress the torque fluctuation of the motor, and the methods of previous scholars are unified and explained; From the motor control strategy, summed up the scholars in the motor torque ripple suppression method strategy; From the perspective of motor torque control allocation strategy, a series of related strategies are elaborated. The previous researchers proposed the neural network PID electronic differential speed torque comprehensive control strategies, electronic differential control algorithms based on sliding mode control, automotive electronic stability program control algorithms based on hierarchical coordinated control strategies, and other control strategies and algorithms. Results: Based on the theoretical model, the theoretical model is verified and tested through software simulation or test platform. The errors of all simulation and test results in the literature and the theoretical model are within the acceptable range. Conclusion: The theoretical model has been verified on the software simulation or test platform, which proves the feasibility and effectiveness of the theoretical model, thereby suppressing torque fluctuations and improving the stability of the vehicle. Finally, the development direction of the key technology of torque ripple suppression for four-wheel in-wheel motor-driven electric vehicles has been prospected.

Influence of Armature Reaction on Electromagnetic Performance and Pole Shaping Effect in Consequent Pole Pm Machines

Consequent pole permanent magnet (CPPM) machines can improve the ratio of average torque to PM volume, but suffer from more serious armature reactions. In this paper, the variations of electromagnetic performance of surface-mounted PM (SPM), conventional CPPM machines, and pole-shaped CPPM machines with armature reaction at currents up to 5 times overload are analyzed and compared. The flux densities, flux linkages, back EMFs, inductances, torque characteristics, and demagnetization withstand capabilities are analyzed by the finite element method (FEM) and frozen permeability method. It is validated that the third order harmonics in inductances for CPPM machines tend to be reduced as current rises since the saturation in iron pole is prone to reducing the saliency effect. But the armature reaction tends to result in the increase of torque ripple components for all the machines. It is also found that the overall torque ripple of asymmetric pole-shaped machine tends to increase significantly under overload conditions. On the contrary, the symmetrical pole-shaped machine can maintain a relatively stable torque ripple under overload conditions which is similar to the SPM counterpart. Additionally, due to the large armature reactions, CPPM machines suffer from weaker demagnetization withstand capabilities and weaker overload capabilities than their SPM counterparts. Four CPPM prototypes with and without pole shaping are tested to confirm the FEM analysis.

Influence of slot/pole number combinations and pole shaping on electromagnetic performance of permanent magnet machines with unbalanced north and south poles

AbstractThe influences of slot/pole number combinations on electromagnetic performances, including flux linkage, inductance, and torque ripple harmonic components etc., resulting from unbalanced characteristics between north and south poles in concentrated winding permanent magnet (PM) machines with symmetrical and asymmetric rotor pole shaping methods are theoretically analysed and experimentally validated in this paper. It shows that for the PM machines with odd number of coils per phase per submachine, including consequent pole (CP) and surface‐mounted PM (SPM) machines, the influences of unbalanced pole characteristics can lead to additional torque ripple harmonics due to additive effects in windings, but can be cancelled in other machines. Compared with symmetrical pole shaping method, asymmetric pole shaping method can result in lower torque ripple for CPPM machines with odd number of coils per phase per submachine, while symmetrical and asymmetric pole shapes have similar effects on torque ripple reduction for other CPPM machines and all the SPM machines. The findings have been validated by finite element analyses on 12‐slot/8‐pole, 12‐slot/10‐pole, 9‐slot/6‐pole, and 12‐slot/14‐pole machines, and by experiments with 12‐slot/8‐pole and 12‐slot/10‐pole CPPM prototypes.

Tuberous Breast Management: A Review of Literature and Novel Technique Refinements.

Sixteen women affected by grade 2 TBD treated with glandular flaps, silicone gel prosthesis, and only an hemiperiareolar incision between January 2018 and January 2019 were reviewed. The age range was 19-27 years (mean age was 25). Follow-up average was 25 months (range 16-33 months). To evaluate the results, we used two analogic scales with values from 1 to 3, where the lower value was the worst result. First, an independent medical team of three plastic surgeons evaluated two parameters: correction of deformity and symmetry. Then, patients were asked to judge the result obtained. The resulting breast has a normal-shaped areola without bulging, a natural shape, a volume matching the contralateral breast, and no evidence of "double-bubble" deformity or irregularities of the lower pole shape. We propose this one-stage approach with hemiperiareolar incision, to minimize time interval to obtain final results in TBD correction, with reduced scar dimensions to avoid all the possible complications related to the round block suture.

The Relationship between the North Atlantic Oscillation and the Silk Road Pattern in Summer

Abstract The Silk Road pattern (SRP), which is the leading mode of upper-tropospheric meridional wind anomalies over midlatitude Eurasia, has been widely used to explain the impacts of the summer North Atlantic Oscillation (SNAO) on East Asian climate. However, the relationship between the SNAO and SRP has not been fully elaborated yet. This study classifies the SNAO into two categories according to whether it is closely associated with the SRP or not: the strongly linked category and weakly linked category, on the interannual time scale. The SNAO of the strongly linked category features a concentrated and significant southern pole over the northwestern Europe, and corresponding significant negative (positive) precipitation and upper-tropospheric wind convergence (divergence) anomalies over the northwestern Europe. The wind convergence (divergence) anomalies directly induce the positive (negative) planetary vortex stretching anomalies, which contribute overwhelmingly to positive (negative) Rossby wave source anomalies of the northwestern Europe. These Rossby wave source anomalies, acting as disturbances, further inspire circulation anomalies of surrounding regions, including meridional wind anomalies over the Caspian Sea, which are crucial for the SRP formation. As a result, the downstream SRP is triggered. All these essential features responsible for a strong SNAO–SRP linkage are weak for the weakly linked category. The SNAO–SRP correspondence on the interdecadal time scale is also discussed, and generally similar results are found. Results suggest the importance of shapes for the SNAO southern pole (including the location, the space extent, and the intensity) in determining whether the SNAO can closely link the SRP. Therefore, the shape of the SNAO southern pole should be involved in the discussion of the SNAO’s remote impacts.

Design and Optimization of Combined-Function Quadrupole-Sextupole Magnets

A lightweight superconducting (SC) gantry with large momentum acceptance is under development at Huazhong University of Science and Technology (HUST). Three types of combined-function quadrupole-sextupole (QS) magnets are used to suppress the chromatic dispersion for the large momentum acceptance. This paper introduces the design and optimization of the QS magnets with adjustable sextupole to quadrupole (S/Q) field ratio. The pole shaping method and asymmetric excitation method are discussed in detail for the design. Considering the magnetic field quality deterioration caused by the asymmetry of the pole face, the contour of the pole face and the pole end chamfer are optimized to minimize the harmonics field. After several iterations, the maximum harmonics of the QS2 magnet can be limited within 1E-03. In addition, we investigate the magnetic center shift, when the S/Q ratio changes.

Numerical simulations of interfacial and elastic instabilities

<h2>Abstract</h2> The interplay of elasticity and capillarity in free-surface flows of viscoelastic fluids gives rise to intriguing flow instabilities. We present novel numerical simulations and analyse the physics related to the appearance of surface distortions on polymer melt extrudates, often referred to as "sharkskin" instability, and the abrupt increase in the rise velocity of a bubble in a viscoelastic solution. Regarding the extrusion process, the transition from smooth to wavy extrudate with increasing flow rate is attributed to a Hopf bifurcation, followed by a sequence of period-doubling bifurcations, which eventually lead to elastic turbulence under creeping flow. We suggest that the inception of these waves is related with intense stretch of polymer chains and subsequent recoil at the region where the melt detaches from the solid wall of the die. The ‘velocity discontinuity' of the rising bubble is attributed to a hysteresis loop, triggered by the change of shape of the rear pole into a tip that favors the formation of intense stress gradients, which reduce the fluid viscosity and facilitate the bubble translation. Finally, we discuss the numerical methodology that has allowed us to obtain stable numerical solutions in highly deformed meshes and for high values of the Weissenberg number.