Statistical properties of filaments in weak gravitational lensing

We study weak lensing properties of filaments that connect clusters of galaxies through large cosmological $N$-body simulations. We select 4639 halo pairs with masses higher than $10^{14}h^{-1}\mathrm{M}_\odot$ from the simulations and investigate dark matter distributions between two haloes with ray-tracing simulations. In order to classify filament candidates, we estimate convergence profiles and perform profile fitting. We find that matter distributions between haloes can be classified in a plane of fitting parameters, which allow us to select straight filaments from the ray-tracing simulations. We also investigate statistical properties of these filaments, finding them to be consistent with previous studies. We find that $35\%$ of halo pairs possess straight filaments, $4\%$ of which can directly be detected at $S/N\geq2$ with weak lensing. Furthermore, we study statistical properties of haloes at the edges of filaments. We find that haloes are preferentially elongated along filamentary structures and are less massive with increasing filament masses. However, the dependence of these halo properties on masses of straight filaments is very weak.Comment: 14 pages, 12 figures, 3 tables. Accepted for publication in MNRA

Stator Design of Alternate Slot Winding for Reducing Torque Pulsation With Magnet Designs in Surface-Mounted Permanent Magnet Motors

This paper proposes a stator design that consists of a combination of an alternate slot winding and dummy slots to minimize pulsating torque in surface-mounted permanent magnet synchronous motors. The alternate arrangement of winding coils is designed to eliminate a harmonic component of back electromotive force that gives rise to a harmonic component of pulsating torque. However, the non-uniform arrangement of slots decreases the frequency of the cogging torque by half and may aggravate torque pulsation. To compensate for the drawback or the decrease in the frequency of the cogging torque, dummy slots are introduced in the alternately slotted stator. A theoretical method is developed for the proposed stator combination. The proposed stator design is applied to a prototype in combination with other rotor magnet design techniques, such as magnet shifting and the adjustment of magnet width, to minimize pulsating torque. The results show that the designed motor reduces the ripple factor of the torque by approximately 30% relative to the original value. In addition, the proposed alternate slot winding is validated by comparing the design with equal slot-winding designs optimized through finite-element method analysis

弱重力レンズ効果による宇宙の構造形成の解明

学位の種別:課程博士University of Tokyo(東京大学

Trends, Treatment Approaches, and In-Hospital Mortality for Acute Coronary Syndrome in Japan During the Coronavirus Disease 2019 Pandemic

Aim: The coronavirus disease 2019 (COVID-19) pandemic has left negative spillover effects on the entire health care system. Previous studies have suggested significant declines in cases of acute coronary syndrome (ACS) and primary percutaneous coronary intervention (PCI) during the COVID-19 pandemic. Methods: We performed a quasi-experimental, retrospective cohort study of ACS hospitalisations by using a multi-institutional administrative claims database in Japan. We used interrupted time series analyses to ascertain impacts on cases, treatment approaches, and in-hospital mortality before and after Japan’s state of emergency to respond to COVID-19. The primary outcome was the change in ACS cases per week. Results: A total of 30, 198 ACS cases (including 21, 612 acute myocardial infarction and 8, 586 unstable angina) were confirmed between 1st July 2018 and 30th June 2020. After the state of emergency, an immediate decrease was observed in ACS cases per week (-18.3%; 95% confidence interval, -13.1 to -23.5%). No significant differences were found in the severity of Killip classification (P=0.51) or cases of fibrinolytic therapy (P=0.74). The impact of the COVID-19 pandemic on in-hospital mortality in ACS patients was no longer observed after adjustment for clinical characteristics (adjusted odds ratio, 0.93; 95% confidence interval, 0.78 to 1.12; P=0.49). Conclusions: We demonstrated the characteristics and trends of ACS cases in a Japanese population by applying interrupted time series analyses. Our findings provide significant insights into the association between COVID-19 and decreases in ACS hospitalisations during the pandemic

Performance of segment type switched reluctance motor using grain-oriented

Authors developed a segment type switched reluctance motor (SRM) as a rare earth less motor. The object is to reduce the acoustic noise and vibration as well as improve the torque characteristics. In this paper, we propose the performance improve method using grain-oriented electric steel as the segment core. The validity is confirmed experimentally.15th International Conference on Electrical Machines and Systems, ICEMS 2012; Sapporo; Japan; 21 October 2012 ～ 24 October 201