Influence of Stator MMF Harmonics on the Utilization of Reluctance Torque in Six-Phase PMA-SynRM with FSCW

Although fractional-slot concentrated winding (FSCW) offers many significant advantages, such as short end-turn windings, high slot filling factor, and low cogging torque, it is frequently limited by excessive stator magnetomotive force (MMF) harmonics which will induce high eddy losses in the permanent magnets (PMs). What is more, in the literature, it can be observed that the reluctance torque of the salient-pole machine with FSCW is usually much lower than that obtained with integral slot winding. To explore the underlying reason why the reluctance torque in a salient machine with FSCW significantly decreases, a new six-phase FSCW with 24 slots and 10 poles, which can significantly reduce the undesirable stator MMF harmonics, is obtained by using the concept of stator shifting. Then, two permanent-magnet-assisted synchronous reluctance machines (PMA-SynRMs) with the proposed winding layout and conventional asymmetric 12-slot/10-pole six-phase winding layout are designed and simulated by the finite-element method (FEM). The reluctance torque, total torque, and d/q-axis inductances with different current phase angles are also compared under different loaded conditions. The results show that a reduction in stator MMF harmonics can indeed lead to a significant enhancement in reluctance torque under heavy loaded conditions, while the dominance will diminish under light loaded conditions

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Factors associated with afebrile presentation and delayed defervescence of bacterial meningitis in children under 3 years of age: a multi-centre retrospective analysis

Abstract Background This multi-center study aimed to identify factors affecting fever and delayed defervescence in bacterial meningitis (BM) patients under 3 years of age because of the variability of fever in this patient population. Methods Only BM patients under 3 years treated at 49 centers in China from November 2018 to end-April 2021 were included in the study. Univariate and multivariate logistic regression analyses were performed to determine factors associated with afebrile presentation and fever of delayed defervescence. Results A total of 863 BM patients under 3 years were included in the study. Coagulase negative staphylococcus was associated with afebrile presentation (OR = 1.176), while septicaemia and ear-nose-throat infections were associated with fever (P < 0.05). The patients with fever were assigned into early and delayed defervescence groups based on defervescence time (less than and more than or equal to one week). Furthermore, Streptococcus agalactiae meningitis (OR = 1.124), concomitant gastrointestinal infection (OR = 1.276), encephalomalacia (or = 1.339), and subdural effusion (OR = 1.454) were independently associated with delayed defervescence (all P < 0.05). Conclusions The findings can aid in the efficient utilization of fever in auxiliary diagnosis and evaluating the condition of the disease