Hybrid Sensor-less Control of Permanent Magnet Synchronous Motor in Low-speed Region

Yamamoto, Yasuhiro,Funato, Hirohito,Ogasawara, Satoshi The Korean Institute of Power Electronics 2008 JOURNAL OF POWER ELECTRONICS Vol.8 No.4

This paper proposes a method of improving the stability in sensor-less control of permanent magnet synchronous motors. The control method for low-speed region is divided into two: One is a high frequency method, which involves a problem of reverse rotation once misdetection of the permanent magnet polarity should occur, and another one is a current drive method, which has a problem that phase and speed oscillations are caused by quick speed changes. Hence, authors propose adoption of the current drive method for the basic control system with added compensation of stabilization by means of the high frequency method. This combination secures stable control with no risk of reversal and less vibration. In addition, authors have also considered a frequency separation filter of a shorter delay time so that current control performance will not lower even when high frequencies are introduced. This filter has achieved simplified compensation using repetitive characteristic through the utilization of the periodicity of high frequency current. Simulation and experiment have been conducted to verify that the stable performance of this system is improved.

Hybrid Sensor-less Control of Permanent Magnet Synchronous Motor in Low-speed Region

Yasuhiro Yamamoto,Hirohito Funato,Satoshi Ogasawara 전력전자학회 2008 JOURNAL OF POWER ELECTRONICS Vol.8 No.4

This paper proposes a method of improving the stability in sensor-less control of permanent magnet synchronous motors. The control method for low-speed region is divided into two: One is a high frequency method, which involves a problem of reverse rotation once misdetection of the permanent magnet polarity should occur, and another one is a current drive method, which has a problem that phase and speed oscillations are caused by quick speed changes. Hence, authors propose adoption of the current drive method for the basic control system with added compensation of stabilization by means of the high frequency method. This combination secures stable control with no risk of reversal and less vibration. In addition, authors have also considered a frequency separation filter of a shorter delay time so that current control performance will not lower even when high frequencies are introduced. This filter has achieved simplified compensation using repetitive characteristic through the utilization of the periodicity of high frequency current. Simulation and experiment have been conducted to verify that the stable performance of this system is improved.

Gastric Adenocarcinoma of Fundic Gland Type with Aggressive Transformation and Lymph Node Metastasis: a Case Report

Yasuhiro Okumura,Manabu Takamatsu,Manabu Ohashi,Yorimasa Yamamoto,Noriko Yamamoto,Hiroshi Kawachi,Satoshi Ida,Koshi Kumagai,Souya Nunobe,Naoki Hiki,Takeshi Sano 대한위암학회 2018 Journal of gastric cancer Vol.18 No.4

A 55-year-old man visited our hospital for a detailed examination of a gastric submucosal tumor that was first detected 10 years prior. The tumor continued to grow and had developed a depressed area in its center. A histopathological examination of biopsy specimens revealed gastric adenocarcinoma of the fundic gland type (GA-FG). It was diagnosed as T2 based on the invasion depth as determined by white-light endoscopy and endoscopic ultrasonography. A total gastrectomy with lymphadenectomy was performed and a GA-FG in the mucosa and submucosa was confirmed histopathologically. However, there was a gradual transition to an infiltrative tubular adenocarcinoma with poorly differentiated components in the muscular and subserosal layers. Metastasis was identified in a dissected lymph node (LN). This is the first report of a GA-FG progressing to an aggressive cancer with LN metastasis. These findings modify our understanding of the pathophysiology of GA-FG.

Hybrid Sensor-less Control of Permanent Magnet Synchronous Motor in Low-speed Region

Yasuhiro Yamamoto,Hirohito Funato,Satoshi Ogasawara 전력전자학회 2007 ICPE(ISPE)논문집 Vol.- No.-

This paper proposes a method of improving the stability in sensor-less control of permanent magnet synchronous motors. The control method for low-speed region is divided into two: One is a high frequency method, which involves a problem of reverse rotation once misdetection of the permanent magnet polarity should occur, and another one is a current drive method, which has a problem that phase and speed oscillations are caused by quick speed changes. Hence, authors propose adoption of the current drive method for the basic control system with added compensation of stabilization by means of the high frequency method. This combination secures stable control with no risk of reversal and less vibration. In addition, authors have also considered a frequency separation filter of a shorter delay time so that current control performance will not lower even when high frequencies are introduced. This filter has achieved simplified compensation using repetitive characteristic through the utilization of the periodicity of high frequency current. Simulation and experiment have been conducted to verify that the stable performance of this system is improved.

Internet Survey of Japanese Patients With Chronic Constipation: Focus on Correlations Between Sleep Quality, Symptom Severity, and Quality of Life

( Sayuri Yamamoto ),( Yurika Kawamura ),( Kazuhiro Yamamoto ),( Yoshiharu Yamaguchi ),( Yasuhiro Tamura ),( Shinya Izawa ),( Hiroaki Nakagawa ),( Yoshinori Wakita ),( Yasutaka Hijikata ),( Masahide Eb 대한소화기기능성질환·운동학회 2021 Journal of Neurogastroenterology and Motility (JNM Vol.27 No.4

Background/Aims Chronic constipation and lifestyle factors can affect sleep quality. We evaluated the relationship between chronic constipation and sleep in the Japanese population. Methods This cross-sectional internet-based survey included 3000 subjects with constipation, classified according to sleep status (good/poor). Primary endpoints were Bristol stool form scale (BSFS) score and correlations between sleep disorder criteria of the Pittsburgh Sleep Quality Index (PSQI) and sleep status (good/poor sleep). Secondary endpoints included correlations between quality of life (QOL) and mood, medical, lifestyle, and sleep factors. Results The proportion of participants with BSFS category 4 (normal stool) was significantly higher in the good sleep group (P < 0.001). Sleep disturbance (P < 0.05), sleep quality, and duration, use of hypnotic medication, and daytime dysfunction of PSQI (all P < 0.001) significantly correlated with poor sleep. In the poor sleep group, QOL was significantly worse and anxiety and depression levels were significantly higher (all P < 0.001) compared with the good sleep group. Anemia and smoking (both P < 0.05), recent body weight increases, and poor eating habits (all P < 0.001) were significantly higher in the poor sleep group. Male sex, onset associated with change in frequency of stools, sensation of incomplete evacuation for at least 25% of defecations, and manual maneuvers to facilitate at least 25% of defecations correlated with poor sleep. Conclusions Subjects with constipation and poor sleep experienced severe symptoms and had poor QOL. These data support the need for a multifocal treatment approach, including lifestyle advice and pharmacotherapy. (J Neurogastroenterol Motil 2021;27:602-611)

Gastric Adenocarcinoma of Fundic Gland Type with Aggressive Transformation and Lymph Node Metastasis: a Case Report

Okumura, Yasuhiro,Takamatsu, Manabu,Ohashi, Manabu,Yamamoto, Yorimasa,Yamamoto, Noriko,Kawachi, Hiroshi,Ida, Satoshi,Kumagai, Koshi,Nunobe, Souya,Hiki, Naoki,Sano, Takeshi The Korean Gastric Cancer Association 2018 Journal of gastric cancer Vol.18 No.4

A 55-year-old man visited our hospital for a detailed examination of a gastric submucosal tumor that was first detected 10 years prior. The tumor continued to grow and had developed a depressed area in its center. A histopathological examination of biopsy specimens revealed gastric adenocarcinoma of the fundic gland type (GA-FG). It was diagnosed as T2 based on the invasion depth as determined by white-light endoscopy and endoscopic ultrasonography. A total gastrectomy with lymphadenectomy was performed and a GA-FG in the mucosa and submucosa was confirmed histopathologically. However, there was a gradual transition to an infiltrative tubular adenocarcinoma with poorly differentiated components in the muscular and subserosal layers. Metastasis was identified in a dissected lymph node (LN). This is the first report of a GA-FG progressing to an aggressive cancer with LN metastasis. These findings modify our understanding of the pathophysiology of GA-FG.

Biomechanical Analysis of a Pedicle Screw-Rod System with a Novel Cross-Link Configuration

Yasuhiro Nakajima,Masahito Hara,Daisuke Umebayashi,Shoichi Haimoto,Yu Yamamoto,Yusuke Nishimura,Toshihiko Wakabayashi 대한척추외과학회 2016 Asian Spine Journal Vol.10 No.6

Study Design: The strength effects of a pedicle screw-rod system supplemented with a novel cross-link configuration were biomechanically evaluated in porcine spines. Purpose: To assess the biomechanical differences between a conventional cross-link pedicle screw-rod system versus a novel crosslink instrumentation, and to determine the effect of the cross-links. Overview of Literature: Transverse cross-link systems affect torsional rigidity, but are thought to have little impact on the sagittal motion of spinal constructs. We tested the strength effects in pullout and flexion-compression tests of novel cross-link pedicle screw constructs using porcine thoracic and lumbar vertebrae. Methods: Five matched thoracic and lumbar vertebral segments from 15 porcine spines were instrumented with 5.0-mm pedicle screws, which were then connected with 6.0-mm rods after partial corpectomy in the middle vertebral body. The forces required for construct failure in pullout and flexion-compression tests were examined in a randomized manner for three different cross-link configurations: un-cross-link control, conventional cross-link, and cross-link passing through the base of the spinous process. Statistical comparisons of strength data were analyzed using Student’s t -tests. Results: The spinous process group required a significantly greater pullout force for construct failure than the control group (p =0.036). No difference was found between the control and cross-link groups, or the cross-link and spinous process groups in pullout testing. In flexion-compression testing, the spinous processes group required significantly greater forces for construct failure than the control and cross-link groups (p <0.001 and p =0.003, respectively). However, there was no difference between the control and cross-link groups. Conclusions: A novel cross-link configuration that features cross-link devices passing through the base of the spinous processes increased the mechanical resistance in pullout and flexion-compression testing compared to un-cross-link constructs. This configuration provided more resistance to middle-column damage under flexion-compression testing than conventional cross-link configuration.

Parallel Computation of Unsteady Flow with Nonequilibrium Condensation Through 3-D Multistage Steam Turbine Cascade

Yasuhiro SASAO,Satoru YAMAMOTO 한국전산유체공학회 2006 한국전산유체공학회 학술대회논문집 Vol.2006 No.5

Numerical Prediction of Unsteady Flows through Whole Nozzle-Rotor Cascade Channels with Partial Admission

Sasao, Yasuhiro,Monma, Kazuhiro,Tanuma, Tadashi,Yamamoto, Satoru Korean Society for Fluid machinery 2009 International journal of fluid machinery and syste Vol.2 No.3

This paper presents a numerical study for unsteady flows in a high-pressure steam turbine with a partial admission stage. Compressible Navier-Stokes equations are solved by the high-order high-resolution finite-difference method based on the fourth-order compact MUSCL TVD scheme, Roe's approximate Riemann solver, and the LU-SGS scheme. The SST-model is also solved for evaluating the eddy-viscosity. The unsteady two-dimensional flows through whole nozzle-rotor cascade channels considering a partial admission are numerically investigated. 108 nozzle passages with two blockages and 60 rotor passages are simultaneously calculated. The influence of the flange in the nozzle box to the lift of rotors is predicted. Also the efficiency of the partial admission stage changing the number of blockages and the number of nozzles is parametrically predicted.

Efficient Algorithms for Solving Facility Layout Problem Using a New Neighborhood Generation Method Focusing on Adjacent Preference

Fukushi, Tatsuya,Yamamoto, Hisashi,Suzuki, Atsushi,Tsujimura, Yasuhiro Korean Institute of Industrial Engineers 2009 Industrial Engineeering & Management Systems Vol.8 No.1

We consider facility layout problems, where mn facility units are assigned into mn cells. These cells are arranged into a rectangular pattern with m rows and n columns. In order to solve this cell type facility layout problem, many approximation algorithms with improved local search methods were studied because it was quite difficult to find exact optimum of such problem in case of large size problem. In this paper, new algorithms based on Simulated Annealing (SA) method with two neighborhood generation methods are proposed. The new neighborhood generation method adopts the exchanging operation of facility units in accordance with adjacent preference. For evaluating the performance of the neighborhood generation method, three algorithms, previous SA algorithm with random 2-opt neighborhood generation method, the SA-based algorithm with the new neighborhood generation method (SA1) and the SA-based algorithm with probabilistic selection of random 2-opt and the new neighborhood generation method (SA2), are developed and compared by experiment of solving same example problem. In case of numeric examples with problem type 1 (the optimum layout is given), SA1 algorithm could find excellent layout than other algorithms. However, in case of problem type 2 (random-prepared and optimum-unknown problem), SA2 was excellent more than other algorithms.