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Projection methods and boundary conditions involving the pressure for incompressible viscous flows
Get PDFWe consider a projection method for time-dependent incompressible Navier—Stokes equations with pressure boundary conditions. The projection method is one of the numerical calculation methods for incompressible viscous fluids often used in engineering. In general, the projection method needs additional boundary conditions to solve a pressure-Poisson equation, which does not appear in the original Navier—Stokes problem. On the other hand, many mechanisms generate flow by creating a pressure difference, such as water distribution systems and blood circulation. Traction and open boundary conditions are often used to impose pressure boundary conditions. We review recent studies on these boundary conditions and propose a new additional boundary condition for the projection method with a Dirichlet-type pressure boundary condition and no tangent flow. We show stability for the scheme and error estimates for the velocity and pressure under suitable norms.departmental bulletin pape
Study of AC-AC converter for PMSM drives for air conditioners in Asia
Get PDFIn recent years, the market for air conditioners in emerging Asian countries such as India and Vietnam has been expanding. Although on-off type air conditioners have been the mainstay of the market, various manufacturers have developed high-efficiency products using inverters and permanent magnet synchronous motors (PMSM), and the ratio of inverters in Japan, China, Europe, and Oceania is increasing. On the other hand, in emerging regions such as Asia, the quality of the power supply is poor, causing frequent power outages as well as instantaneous voltage fluctuations and voltage drops. In addition, high-efficiency operation is required for power converters. This is because there is an efficiency index called APF (Annual Performance Factor) in the performance index of air conditioners, and these performances are directly related to the performance of air conditioners and even to the sales of products. Generally, an AC/DC converter is used to obtain the DC power necessary for the inverter that drives the motor from the AC power supplied to the air conditioner. AC/DC converters that have a function of suppressing harmonics of the input system current in addition to the power conversion function are called PFC (Power Factor Correction) converters in particular. In this study, we propose a partial switching method based on the commonly used PI control to stop the switching operation of the power converter near the peak of the AC voltage by appropriately adjusting the DC voltage command value, thereby reducing the switching losses. This method reduces the switching loss and thus improves the efficiency of PFC converters.departmental bulletin pape
Doctor - Patient Relationship in Psychiatric Medicine, Part 5 : An Introduction to the Contract Law of Psychiatric Medicine
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Water Purification Techniques Using Concrete Waste
Get PDFConcrete is an essential material for construction and human society, and it is used in large quantities all over the world. Considering achievement of a circular society, it is important to properly treat and reuse various wastes derived from the use of concrete. The hydrated cement part of concrete contains highly reactive alkaline calcium compounds, such as calcium hydroxide, calcium silicate hydrates, and ettringite, which can be used in water-purification methods. This article introduces various fundamental investigations for using concrete waste for waterpurification techniques, such as removal of phosphorus, arsenic, and boron.departmental bulletin pape
Characteristics of Science Education at Seikei Junior and Senior High School : What I Got and What I Gave
Get PDF成蹊学園は2024年で旧制成蹊高等学校の開設100周年を迎える． 旧制成蹊高等学校においては， 成蹊小学校ですでに実践されていた「労作教育」「直観教育」といった大正自由教育の理念が「理化教育」として結実した． 理化教育というのは， それを唱導した加藤藤吉教諭にとって， 単に物理・化学の総称というわけではなく， 自然現象をありのまま正しく観察する，実験を中心とした教育というニュアンスをもっていた．こうした教育実践の方法は，戦後の学制改革後も成蹊中学・高等学校の理科の各科目に営々と受け継がれていた．本号では，1970年代に成蹊中高で学び，そして，1980年代の6年間を成蹊中高の地学の教諭としてご活躍された倉茂好匡氏に，生徒として学んだ成蹊の理化教育，また，教師として実践した成蹊の理化教育について， 研究者としてのご自身のキャリア形成とも結びつけて，回想録をご執筆いただいた．（編集委員会記）departmental bulletin pape
A Study of Effective Disclosure : With Special Reference to Segment Information on Nonprofit Organizations
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A Way of Supplying Revenue Source of a Community Inclusive Society (1)
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