•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.
Variable phase-pole machines have the potential to extend the operational range to higher speeds through magnetic pole changes. The state-of-the-art vector-space decomposition (VSD) cannot model the ...transient behavior of the pole change for any possible phase-pole configuration as it creates a discontinuity. The proposed harmonic-plane decomposition (HPD) theory solves this issue by generalizing the VSD to the fullest extent by using its discrete Fourier transformation interpretation. The theory for indirect rotor field-oriented control is developed using the HPD. A controlled, loaded pole change on a wound independently-controlled stator-coils machine using two transition strategies shows the HPD-based controller's ability to maintain torque in the transition. Additionally, the proposed controller accomplishes real harmonic injection and balanced steady-state operation.
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.
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.
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.
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.
The existence of a pre-Rodinia Precambrian supercontinent, variously called Nuna or Columbia, has been widely speculated in the past decade, but the precise timing of its existence and its ...configuration have been uncertain due to the lack of unequivocal paleomagnetic and geological constraints. Here we report high-quality paleomagnetic results from the well dated ∼1780Ma Xiong'er Group in southern North China Block (NCB). A total of 110 paleomagnetic samples from 14 sites were collected and subjected to stepwise thermal demagnetization. After removing a low temperature component (CL) of viscous magnetic remanence acquired in recent geomagnetic field, a high temperature component (CH), carried by hematite and magnetite in redbeds and volcanic samples, has been isolated. It gives a mean direction of (D=18.4°, I=−3.7°, α95=7.6°, N=14) after bedding correction, and a corresponding paleomagnetic pole at 50.2°N, 263.0°E (A95=4.5°). The CH passed a reversal test and was interpreted as a primary remanence. This new pole plus three other high-quality poles from the NCB that have been more precisely dated at 1769±3Ma, 1560–1440Ma and 1437±21Ma define a 1780–1440Ma apparent polar wander path (APWP) for the NCB. This, together with an update of global high quality paleomagnetic dataset, allows us to demonstrate that the pre-Rodinia supercontinent Nuna likely existed at least between ∼1780Ma and ∼1400Ma. Our paleomagnetism-based global reconstruction, for the first time, quantitatively assembles all major cratons together; it encompasses previously proposed regional links including the SAMBA connection between Baltica, Amazonia and Western Africa (Johansson, 2009), connections between Laurentia, Baltica and Siberia at the core of Nuna (Evans and Mitchell, 2011), the proto-SWEAT connection between Laurentia, East Antarctica and Australian blocks (Payne et al., 2009), and the NCB–India connection (Zhao et al., 2011).
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► We report a ∼1780Ma high quality paleomagnetic pole for North China, and review other paleomagnetic results. ► We establish the first geologically and paleomagnetically viable configuration of the Nuna supercontinent. ► We depict the paleogeographic positions of Nuna at ∼1740Ma and 1590Ma, and a lifespan of ca. 1.8–1.4Ga.
Two-Level Stability Analysis of Complex Circuits Suarez, Almudena; Ramirez, Franco
IEEE transactions on microwave theory and techniques,
2021-Jan., 2021-1-00, 20210101, Letnik:
69, Številka:
1
Journal Article
Recenzirano
Odprti dostop
A new methodology is proposed for the small- and large-signal stability analysis of complex microwave systems, containing multiple active blocks. It is based on a calculation of the system ...characteristic determinant that ensures that this determinant does not exhibit any poles on the right-hand side (RHS) of the complex plane. This is achieved by partitioning the structure into simpler blocks that must be stable under either open-circuit (OC) or short-circuit (SC) terminations. Thus, the system stability is evaluated using a two-level procedure. The first level is the use of pole-zero identification to define the OC- or SC-stable blocks, which, due to the limited block size, can be applied reliably. In large-signal operation, the OC- or SC-stable blocks are described in terms of their outer-tier conversion matrices. The second level is the calculation and analysis of the characteristic determinant of the complete system at the ports defined in the partition. The roots of the characteristic determinant define the stability properties. The Nyquist criterion can be applied since, by construction, the determinant cannot exhibit any poles in the RHS. In addition, one can use pole-zero identification to obtain the values of the determinant zeroes. Because the determinant is calculated at a limited number of ports, the analysis complexity is greatly reduced.
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