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Hydrographic Model Test on Prevention against Vortex Occurrence for Vertical Bulb Turbine
Yamato, Shoichi,Nakamura, Shogo,Furukawa, Akinori Korean Society for Fluid machinery 2009 International journal of fluid machinery and syste Vol.2 No.4
A vertical bulb turbine unit with elbow type draft tube has been developed due to avoidance of complicated assembling and long standstill period at overhaul in comparison with conventional horizontal bulb turbine unit. Before designing the prototype vertical bulb unit, a hydrographic model test was carried out to establish the ideal design concept for this innovative generating unit. Froude similarity is not available for vortex occurrence. Consequently, an intake structure without air entraining vortices under all the flow conditions is developed, and it is confirmed that the surge wave at load rejection is not affected harmful influence for other constructions.
Yamato Yu,Hasegawa Tomohiko,Yoshida Go,Banno Tomohiro,Oe Shin,Arima Hideyuki,Mihara Yuki,Ushirozako Hiroki,Yamada Tomohiro,Watanabe Yuh,Ide Koichiro,Nakai Keiichi,Kurosu Kenta,Matsuyama Yukihiro 대한척추외과학회 2022 Asian Spine Journal Vol.16 No.5
Study Design: Single-center retrospective case series.Purpose: We aimed to evaluate the clinical results of revision surgery for a rod fracture using a posterior-only approach and determine the best procedure to prevent refracture in patients with adult spinal deformity (ASD).Overview of Literature: ASD affects the thoracolumbar spine and often requires surgical correction. However, surgery for extensive spinal fusion causes rod fracture, a major mechanical complication. Few studies have described the treatment methods for rod fractures. Furthermore, the clinical outcomes of revision surgery for rod fractures in patients with ASD are currently unclear.Methods: We retrospectively reviewed the medical records of 404 patients who underwent corrective fusion surgery for ASD with a minimum 2-year follow-up. We studied cases of reoperation for postoperative rod fractures and investigated surgical procedure, intraoperative findings, clinical course, and rod refracture following revision surgery.Results: Rod fracture was observed in 88 patients (21.8%). Fifty-three patients (average age, 68.3 years; average blood loss, 502.2 mL [% estimated blood volume=16.4%]; and operation time, 203.3 minutes) who suffered from a rod fracture at an average of 28.3 months after the primary operation underwent reoperation. Surgical invasiveness had no significant differences in total or partial rod replacement; however, the procedures with and without an anterior bone graft significantly differed. The replaced rod refractured at an average of 35.3 months after the revision surgery of five patients. The rod also refractured at a level outside multiple rods in two patients and with traumatic episodes in three patients. Three patients had bone grafts in the anterior column.Conclusions: Revision surgery involving a multirod with a posterior-only approach for a rod fracture that occurred after ASD was performed successfully. Bone grafting in the anterior column is unnecessary for patients without massive bone defects.
Attitude Stabilization of an Aircraft via Nonlinear Optimal Control Based on Aerodynamic Data
Yuhei Yamato,Noboru Sakamoto,Morio Takahama 제어로봇시스템학회 2009 제어로봇시스템학회 국제학술대회 논문집 Vol.2009 No.8
In this paper, a stabilization problem for an aircraft at a high angle of attack is considered. Though aircrafts obtain large lift force over the high angle of attack regime, nonlinearities of aerodynamics over the regime are considerably high. Using aerodynamic coeffients data given as a table, we design a nonlinear optimal control law to stabilize an existing aircraft at a high angle of attack by a new method based on stable manifold theory. As a result, the nonlinear optimal control law stabilizes attitudes of the aircraft in a larger region than the linear optimal control does.
Shuntaro Yamato,Kenichi Nakanishi,Norikazu Suzuki,Yasuhiro Kakinuma 한국정밀공학회 2021 International Journal of Precision Engineering and Vol.22 No.2
To maximize the potential for high material removal rates in simultaneous processes such as parallel milling, developing strategies for successful chatter suppression/avoidance is an important concern for manufacturers. In this study, the effectiveness of the spindle speed difference method (SDM) for chatter suppression is discussed in a parallel end-milling process where a flexible workpiece is machined by two tools rotating in opposite direction. The process model is developed, considering that the dynamic variation due to the regenerative eff ect occurs on a plane perpendicular to the tool axis direction. Through the process simulations and the experiments, this study provides informative discussion for comprehending the process behavior. Additionally, a real-time active chatter suppression system with adaptive SDM, where the spindle speed difference is sequentially optimized during the process according to the tracked chatter frequency, is developed by integrating a chatter monitoring system based on sensorless cutting force estimation with sliding discrete Fourier transform. The results show that the developed real-time adaptive system of spindle speed suppresses chatter vibrations more effectively than non-adaptive SDM system; hence, the integrated system can contribute self-optimizing machining systems oriented to Industry 4.0.
Fabrication of Nanocomposite Powders by Sonochemical Method
Hayashi, Yamato,Sekino, Tohru,Niihara, Koichi The Korean Powder Metallurgy Institute 2001 한국분말재료학회지 (KPMI) Vol.8 No.3
Nano particles have recently been a major research interest, motivated by their unusual physical and chemical properties. Such particles can be synthesized using physical and chemical methods. The physical methods need expensive installation like vacuum induction furnace, whereas in chemical methods the process in generally very simple and low cost. In this study, simple and new fabrication process by using ultrasound was investigated to prepare the nano-sized metal particles on various powders at room temperature.
Koichiro Yamato,Akira Sasaki,Takayasu Ito,Isamu Yoshitake 한국콘크리트학회 2020 International Journal of Concrete Structures and M Vol.14 No.2
In regions where the concrete structures are exposed to a salty environment, the concrete requires high resistance to chloride-ion penetration. To achieve higher resistance against chloride ingress, a pozzolanic admixture incorporating a high volume of SiO₂ and Al₂O₃ has been developed. The admixture is a fine mineral powder with a specific surface area of 13,000 m²/kg or higher. It is typically mixed with the concrete at a cement replacement level of 5-13 mass% (20-40 kg/m³). To demonstrate the applicability of the admixture to general ready-mix concretes, this study examined the fundamental properties of concrete cured under standard conditions regarding resistance against chloride ingress. Chloride immersion tests revealed high resistance against penetration of concrete produced with the admixture. Pore-size distribution analysis confirmed that the volume of pores less than 0.01 μm diameter increased whereas a decrease of large pores occurred (0.1 μm diameter or larger). The major contributor to the high resistance was found to be the immobilization of penetrating chloride ions by the formation of Friedel’s salt.
名古屋城下における如來敎信仰 -佛敎と如來敎、そして「いかに救われるか」という問い-
( Ishihara Yamato ) 동서대학교 일본연구센터 2012 次世代 人文社會硏究 Vol.8 No.-
Nyoraikyo is a religion which founded by former samurai servant Kino in Nagoya castle town in 1802.Nyoraikyohas beenviewed as ``Minshushukyo`` which is a concept of Japanese historical studies.This concept has been appreciated because it`s established by people, which means a movement from pre-modern to modern in Japanese history. But, I have some questions. Is only ``Minshushukyo`` important? Are there any differences between ``Minshushukyo`` and the other religions in the same age? In this essay, first,I`d like to focus on the Buddhism which has been ignored in studies of ``Minshushukyo``, and the internal religious controversies of ``Jodo-ShinSect``shouldbe noticed since it happened in the same age with Nyoraikyo.Secondly, I attend topoint out that they have same problems.At last, I`ll try torevaluethe ``Minshushukyo`` relatively in 19th century.