This paper proposes a new algorithm, very efficient numerically, used for locating zeros and poles of complex function and its exemplary applications in microwave technique problems. The algorithm ...starts its run from two arbitrary regions on the complex plane, where the searched function yields values with different signs for either or both real and imaginary parts. The algorithm runs along the path created by the chain of equilateral triangles, at whose vertices the function is evaluated. When analyzing the signs of the function, the tracking directions are chosen along the borders of complex regions, where zeros/poles are further expected. Calculations of complex propagation coefficients for a slab dielectric waveguide, complex dispersion coefficients of graphene transmission lines, and a zero/pole analysis of microwave filters are given to show some of the possible applications of the proposed algorithm. A comparison to other methods is also included.
•Impacts of key design variables on the failure probability of poles are not known.•Proposed multi-dimensional pole fragility models characterize variables’ effects.•The fragility models assume a ...lognormal CDF for wind velocity as the IM.•These models facilitate accurate wind risk analysis of power distribution networks.•They also support upgrade or replacement decisions for wood utility poles.
Risk assessment and life cycle cost analysis of electric power systems facilitate analysis and efficient management of compound risks from wind hazards and asset deteriorations. Fragility functions are key components for these analyses as they provide the probability of failure of poles given the hazard intensity. Despite a number of efforts that analyzed the wind fragility of utility wood poles, impacts of key design variables on the likelihood of failure of poles have not been yet characterized. This paper, for the first time, provides a set of multi-dimensional fragility models that are functions of key factors including class, age, and height of poles, number and diameter of conductors, span length, and wind speed and direction. Unlike existing generic pole fragility models, this new class of fragility functions is able to accurately represent various configurations of power distribution systems. Therefore, it can reliably support decisions for installation of new or replacement of existing damaged or decayed poles. The generated fragility models are also used to investigate impacts of design variables. For example, results indicate that when height is considered as a covariate for the fragility function, the likelihood of failure of wood poles for a given height increases with class number. However, if height is treated as an uncertain variable, and therefore, excluded as a covariate from the fragility model, lower classes of poles may have higher failure probability as they are often used for higher clearance limits.
This paper proposes an advanced technique to develop combined neural network and pole-residue-based transfer function models for parametric modeling of electromagnetic (EM) behavior of microwave ...components. In this technique, neural networks are trained to learn the relationship between pole/residues of the transfer functions and geometrical parameters. The order of the pole-residue transfer function may vary over different regions of geometrical parameters. We develop a pole-residue tracking technique to solve this order-changing problem. After the proposed modeling process, the trained model can be used to provide accurate and fast prediction of the EM behavior of microwave components with geometrical parameters as variables. The proposed method can obtain better accuracy in challenging applications involving high dimension of geometrical parameter space and large geometrical variations, compared with conventional modeling methods. The proposed technique is effective and robust especially in solving high-order problems. This technique is illustrated by three examples of EM parametric modeling.
The pericentriolar material (PCM) that accumulates around the centriole expands during mitosis and nucleates microtubules. Here, we show the cooperative roles of the centriole and PCM scaffold ...proteins, pericentrin and CDK5RAP2, in the recruitment of CEP192 to spindle poles during mitosis. Systematic depletion of PCM proteins revealed that CEP192, but not pericentrin and/or CDK5RAP2, was crucial for bipolar spindle assembly in HeLa, RPE1, and A549 cells with centrioles. Upon double depletion of pericentrin and CDK5RAP2, CEP192 that remained at centriole walls was sufficient for bipolar spindle formation. In contrast, through centriole removal, we found that pericentrin and CDK5RAP2 recruited CEP192 at the acentriolar spindle pole and facilitated bipolar spindle formation in mitotic cells with one centrosome. Furthermore, the perturbation of PLK1, a critical kinase for PCM assembly, efficiently suppressed bipolar spindle formation in mitotic cells with one centrosome. Overall, these data suggest that the centriole and PCM scaffold proteins cooperatively recruit CEP192 to spindle poles and facilitate bipolar spindle formation.
This paper investigates the influence of stator/rotor pole number combinations and permanent magnet (PM) numbers on electromagnetic performance of consequent-pole hybrid excited flux reversal ...machines (CP-HEFRMs), which have different numbers of PM poles and iron poles and concentrated AC and DC windings on the stator and a salient pole rotor. PMs in the slots of one stator pole are magnetized radially in the same direction, while opposite on adjacent stator poles. Magnetic field paths of DC, PM, and hybrid excitations are investigated. The phenomenon of flux cancellation, i.e., PM and DC MMFs in CP-HEFRMs are of opposite polarities in the flux-enhancing operating mode, is revealed and verified, for the first time, as the key feature that makes CP-HEFRMs different from other hybrid excited machines. Consequently, the saturation in stator pole and yoke can be mitigated and hence the overload capability of DC excitation is enhanced, which is verified by finite element analysis (FEA). Global optimizations are utilized to obtain the optimal rotor and stator pole number combinations and PM numbers for each stator pole. Torque, torque ripple, inductance, unbalanced magnetic force, and flux regulation capability are compared for different PM numbers and rotor pole numbers. Comparisons are made on consequent-pole and non-consequent-pole topologies in terms of torque capacity, flux regulation capability, and PM consumption to further illustrate the advantages of consequent-pole topology. A prototype machine is built and tested to validate the analyses.
This paper investigates the design principles and performance optimization for segmented-rotor switched reluctance motors (SRSRMs) with different rotor pole numbers for belt-driven starter generators ...of hybrid electric vehicles. For the design principles, several constraints are derived for the numbers of stator and rotor poles, the dimensions, and the number of winding turns. Two SRSRMs with 16/10 and 16/14 stator/rotor poles are presented according to these principles. For the performance optimization, the two motors are optimized individually for maximizing the torque. To evaluate the effect of different segmented-rotor numbers, the overall performances of the two SRSRMs are investigated and compared. It is found that the 16/14 SRSRM has higher flux linkage and static torque. The 16/14 SRSRM exhibits higher torque and lower torque ripple at low speed operation, whereas at high speed, the 16/10 SRSRM performs better in terms of torque and power densities. Compared with the 16/14 SRSRM, the 16/10 SRSRM has higher final steady speed under the same startup condition. The 16/10 SRSRM can achieve higher steady speed under starter mode and provide higher generated power under braking mode. Moreover, the 16/10 SRSRM exhibits higher efficiency in the most feasible speed range, especially in high speed range, and it has wider high-efficiency area. Finally, a 16/10 SRSRM is prototyped and tested to validate the simulation results.
Fiber-reinforced polymers poles were on the increase because they were lightweight, have high strength-to-weight ratios, provide corrosion resistance, can be customized to meet strength and ...deflection requirements, and have a low life-cycle cost of construction and maintenance. This research presents a comprehensive review of all significant research and existing case studies to review the present knowledge concerning fiber-reinforced polymers poles. The main summary covers 70 works focusing on fiber poles to summarize recent activities on selected relevant topics and highlight possible future implementations. In this context, this study discusses fiber-reinforced polymers poles in six aspects: (i) introduction; (ii) methodology; (iii) Materials properties of FRP poles; (iv) manufacturing techniques of FRP poles; (v) testing of FRP poles (static and dynamic flexure test as cantilever beam); (vi) modeling of FRP poles. Therefore, this critical review will demonstrate an overview of FRP Poles manufacturing techniques (Pultrusion, filament winding, centrifugal process, and hand lay-up) and which Pultrusion technique is the best suited for FRP Poles. Static modeling was the most used of other techniques.
Line-start permanent magnet synchronous motors (LSPMSMs) have become superior to induction motors in general industrial applications due to their high efficiency, improved power factor, and enhanced ...torque density. However, the LSPMSM suffers the poor starting torque owing to the existence of the braking and pulsating torque at start-up, which seriously plagues its development. Therefore, this paper presents a novel LSPMSM with 6/8 pole changing stator windings, which can fundamentally improve the starting capability. At the beginning of the starting, the 6-pole stator windings are energized, whereas the rotor permanent magnets are 8 poles, so the braking torque and pulsating torque can be highly decreased. When the motor reaches a certain speed, the stator winding changes to 8 poles to pull into synchronization and stable operation. The design of the 6/8 pole changing winding is presented based on the slot-number phase diagram method. Then, the starting process of the conventional and the proposed pole changing LSPMSMs are analyzed and compared. Through the calculation of impedance parameters and the analysis of magnetic fields at the start-up, the torque components are calculated utilizing the analytical calculation method. Finally, the experiments are carried out to verify the validity and superiority of the proposed design and method.
In this article, we analyze the back electromotive force (EMF) harmonic characteristics influenced by the slot-pole combinations in permanent magnet vernier motors for in-wheel drive applications. ...First, the feasible matches among the slot-pole combinations, stator tooth types, as well as winding topologies are given. Second, the expressions of fundamental and harmonic back EMF are then derived, where the equivalent winding factor considering the air-gap permeance harmonics is introduced to evaluate the back EMF fundamental amplitude. Next, the contribution of each air-gap magnetic-field harmonic on the back EMF harmonic is investigated, which has proven that the air-gap odd-order ineffective magnetic-field harmonics are responsible for unexpected back EMF harmonics. Based on this, the feasible principle of the number of permanent magnet (PM) poles, armature poles, and flux modulation poles aiming at the low ineffective back EMF harmonics is established. Finally, extensive finite-element analysis (FEA) is conducted, and two prototypes are manufactured and tested, where the experimental results have good agreement with the FEA and theoretical results.
Developing a permanent magnet synchronous machine (PMSM) for direct-drive electric vehicle (EV) has challenges such as obtaining high torque density and low torque ripple. The PMSM should have high ...pole numbers owing to low-speed operation, thereby increasing the use of rare earth magnets and cost. Therefore, in this article a consequent pole (CP) rotor topology is proposed in which the permanent magnet (PM) volume is reduced when compared with conventional surface PMSM (SPMSM). However, replacing south poles in an SPMSM with induced steel poles can increase torque ripple and reduce torque density. In order to improve torque density in a CP PMSM, structural modifications such as multilayer windings and non-ferromagnetic barriers have been proposed in the literature. These modifications increased the torque density while increasing the torque ripple. Therefore, this article proposes a novel two-level optimization method based on gradient descent algorithm, to address the challenges of improving torque density and reducing torque ripple simultaneously in a CP PMSM. Initially, an expression for the magnet pole arc angle is derived for CP PMSM based on magnetic equivalent circuit. A two-level optimization is performed on a baseline CP PMSM to determine the optimal magnet pole arc. The torque production and torque ripples of the optimized design are validated by simulation and experimental results.
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