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Global and Kinetic MHD Simulation by the Gpic-MHD Code

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Plasma Science and Technology 2011年第5期13卷 528-534页

作者： Hiroshi NAITOU Yusuke yamada Kenji KAJIWARA Wei-li LEE Shinji TOKUDA Masatoshi YAGI Graduate School of Science and Engineering Yamaguchi University Princeton Plasma Physics Laboratory International Fusion Energy Research Center Research Institute for Applied Mechanics Kyushu University Japan Atomic Energy Agency

In order to implement large-scale and high-beta tokamak simulation, a new algorithm of the electromagnetic gyrokinetic PIC （particle-in-cell） code was proposed and installed on the Gpic-MHD code [Gyrokinetic PIC code for magnetohydrodynamic （MHD） simulation]. In the new algorithm, the vorticity equation and the generalized Ohm＇s law along the magnetic field are derived from the basic equations of the gyrokinetic Vlasov, Poisson, and Ampere system and are used to describe the spatio-temporal evolution of the field quantities of the electrostatic potential φ and the longitudinal component of the vector potential Az. The basic algorithm is equivalent to solving the reduced-MHD-type equations with kinetic corrections, in which MHD physics related to Alfven modes are well described. The estimation of perturbed electron pressure from particle dynamics is dominant, while the effects of other moments are negligible. Another advantage of the algorithm is that the longitudinal induced electric field, ETz = -δAz/δt, is explicitly estimated by the generalized Ohm＇s law and used in the equations of motion. Furthermore, the particle velocities along the magnetic field are used （vz-formulation） instead of generalized momentums （pz-formulation）, hence there is no problem of ＇cancellation＇, which would otherwise appear when Az is estimated from the Ampere＇s law in the pz-formulation. The successful simulation of the collisionless internal kink mode by the new Gpic-MHD with realistic values of the large-scale and high-beta tokamaks revealed the usefulness of the new algorithm.

关键词： tokamak gyrokinetic theory magnetohydrodynamics internal kink mode

Antarctic Radiosonde Observations Reduce Uncertainties and Errors in Reanalyses and Forecasts over the Southern Ocean:An Extreme Cyclone Case

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Advances in Atmospheric Sciences 2020年第5期37卷 431-440页

作者： Kazutoshi SATO Jun INOUE Akira YAMAZAKI Naohiko HIRASAWA Konosuke SUGIURA Kyohei yamada Kitami Institute of Technology Kitami 090-8507Japan Application Laboratory Japan Agency for Marine-Earth Science and TechnologyYokohama 236-0001Japan National Institute of Polar Research Tachikawa 190-8518Japan SOKENDAI(Graduate University for Advanced Studies) Hayama 240-0193Japan University of Toyama Toyama 930-8555Japan

Cyclones with strong winds can make the Southern Ocean and the Antarctic a dangerous *** weather forecasts are essential for safe shipping in the Southern Ocean and observational and logistical operations at Antarctic research *** study investigated the impact of additional radiosonde observations from Research Vessel"Shirase"over the Southern Ocean and Dome Fuji Station in Antarctica on reanalysis data and forecast experiments using an ensemble data assimilation system comprising the Atmospheric General Circulation Model for the Earth Simulator and the Local Ensemble Transform Kalman Filter Experimental Ensemble Reanalysis,version 2.A 63-member ensemble forecast experiment was conducted focusing on an unusually strong Antarctic cyclonic *** data with(observing system experiment)and without(control)additional radiosonde data were used as initial *** observing system experiment correctly captured the central pressure of the cyclone,which led to the reliable prediction of the strong winds and moisture transport near the ***,the control experiment predicted lower wind speeds because it failed to forecast the central pressure of the cyclone *** were found in cyclone predictions of operational forecast systems with and without assimilation of radiosonde observations from Dome Fuji Station.

关键词： radiosonde data assimilation TIGGE Antarctica weather forecast

Numerical Investigation of Flow Fields in Inductively Coupled Plasma Wind Tunnels

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Plasma Science and Technology 2014年第10期16卷 930-940页

作者：喻明浩 Yusuke TAKAHASHI Hisashi KIHARA Ken-ichi ABE Kazuhiko yamada Takashi ABE Department of Aeronautics and Astronautics Kyushu UniversityFukuoka 819-0395Japan Division of Mechanical and Space Engineering Hokkaido UniversitySapporo 060-8628Japan Institute of Space and Astronautical Science Japan Aerospace Exploration AgencySagamihara 252-5210Japan

Numerical simulations of 10 kW and 110 kW inductively coupled plasma （ICP） wind tunnels were carried out to study physical properties of the flow inside the ICP torch and vacuum chamber with air as tile working gas. Two-dimensional compressible axisymmetric Navier- Stokes （N-S） equations that took into account 11 species and 49 chemical reactions of air, were solved. A heat source model was used to describe the heating phenomenon instead of solving the electromagnetic equations. In the vacuum chamber, a four-temperature model was coupled with N-S equations. Numerical results for tile 10 kW ICP wind tunnel are presented and discussed in detail as a representative case. It was found that the plasma flow in the vacuum chamber tended to be in local thermoehemical equilibrium. To study the influence of operation conditions on the flow field, simulations were carried out for different chamber pressures and/or input powers. The computational results for the above two ICP wind tunnels were compared with corresponding experimental data. The computational and experimental results agree well, therefore the flow fields of ICP wind tunnels can be clearly understood.

关键词： inductively coupled plasma Joule heating vacuum chamber chemical reactions

A case of eosinophilic cholangitis:Imaging findings ofcontrast-enhanced ultrasonography, cholangioscopy, andintraductal ultrasonography

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World Journal of Gastroenterology 2007年第13期13卷 1995-1997页

作者： Naoki Matsumoto Kiyoshi Yokoyama Kazuhiko Nakai toshiki Yamamoto Takeshi Otani Masahiro Ogawa Naohide Tanaka Ariyoshi Iwasaki Yasuyuki Arakawa Masahiko Sugitani Department of Gastroenterology and Hepatology Nihon University Surugadai Hospital 1-8-13 Kandasurugadai Chiyoda-ku Tokyo 101-8309 Japan Department of Pathology Nihon University School of Medicine 30-1 Oyaguchikamimachi Itabashi-ku Tokyo 101-8309 Japan

A 38-year-old woman was referred to our institution due to epigastralgia. She presented with obstructive jaundice and eosinophilia. Endoscopic retrograde cholangiopancreatography showed diffuse narrowing from the distal common bile duct to the bifurcation of the hepatic ducts. An endoscopic plastic biliary stent was inserted; the specimen obtained from the common bile duct wall revealed dense infiltration by eosinophils. Treatment was started with prednisolone 60 mg daily. The patient's biliary stenosis and eosinophilia gradually improved. Eosinophilic infiltration in the lungs or stomach is relatively common, but it is rare in the common bile duct. Most of the reported cases of eosinophilic cholangitis presented with eosinophilia; our patient's eosinophil count was over 1000/mm3. Since our patient had allergies to pollen and house dust, a relationship between the allergies and the eosinophilic cholangitis was suspected, but no cause was identified.

关键词： Eosinophilic cholangitis Sclerosingcholangitis, Contrast-enhanced ultrasonography Cholangioscopy, Intraductal ultrasonography

Integrated in-process chatter monitoring and automatic suppression with adaptive pitch control in parallel turning

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Advances in Manufacturing 2018年第3期6卷 291-300页

作者： Shuntaro Yamato Yuki yamada Kenichi Nakanishi Norikazu Suzuki Hayato Yoshioka Yasuhiro Kakinuma Department of System Design Engineering Keio University3-14-1 Hiyoshi Kohoku-ku Yokohama 223-8522 Japan Nakamura-Tome Precision Industry Co. Ltd. 15 NetsunoHakusan Ishikawa 920-2195 Japan Department of Mechanical Science and Engineering Nagoya University Furo-cho Chikusa-ku Nagoya 464-8603 Japan Precision and Intelligent Laboratory Tokyo Institute of Technology 4259-G2-19 Nagatsuta Midori-kuYokohama 226-8503 Japan

Simultaneous processes such as parallel turningor milling offer great opportunities for more efficientmanufacturing because of their higher material removalrates. To maximize their advantages, chatter suppressiontechnologies for simultaneous processes must be devel-oped. In this study, we constructed an automatic chattersuppression system with optimal pitch control for shared-surface parallel turning with rigid tools and a flexibleworkpiece, integrating in-process chatter monitoring basedon the cutting force estimation. The pitch angle betweentwo tools is tuned adaptively in a position control system inaccordance with the chatter frequency at a certain spindlespeed, in a similar manner as the design methodology forvariable-pitch cutters. The cutting force is estimatedwithout using an additional external sensor by employing amulti-encoder-based disturbance observer. In addition, thechatter frequency is measured during the process by per-forming a low-computational-load spectrum analysis at acertain frequency range, which makes it possible to cal-culate the power spectrum density in the control system ofthe machine tool. Thus, the constructed system for automatic chatter suppression does not require any addi-tional equipment.

关键词： Chatter Multitasking machine tool Parall elturning Adaptive control Sensorless Disturbance observer

Strictly Transparent Wavelength Conversion Using Multi-Wavelength Signal Generation

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光学学报 2003年第S1期23卷 351-352页

作者： Eiichi yamada Hiroaki Sanjoh Yuzo Yoshikuni NTT Photonics Laboratories NTT Corporation 3-1 Morinosato Wakamiya Atsugi Kanagawa 243-0198 JapanNTT Photonics Laboratories NTT Corporation 3-1 Morinosato Wakamiya Atsugi Kanagawa 243-0198 JapanNTT Photonics Laboratories NTT Corporation 3-1 Morinosato Wakamiya Atsugi Kanagawa 243-0198 Japan

We succeeded in strictly transparent wavelength conversion by means of channel selection from multi-wavelength signals generated by sinusoidal modulation of input signal. Modulation-format-independent and bit-rate-ind... 详细信息

关键词： that in rate were mode of NRZ from AWG Figure

Investigation on Retention and Release Behaviors of Hydrogen and Helium in Vanadium Alloy

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Plasma Science and Technology 2005年第3期7卷 2835-2838页

作者：刘翔 Tsuyoshi yamada Yuji Yamauchi Yuko Hirohata Tomoaki Hino Nobuaki Noda Southwestern Institute of Physics Chengdu 610041 China Laboratory of Plasma Physics and Engineering Hokkaido UniversityKita-13 Nishi-8 Kita-ku Sapporo 060-8628 Japan National Institute for Fusion Science Toki-shi Gifu-ken 509-5202 Japan

Vanadium alloy is proposed as an attractive candidate for first wall and blanket structural material of fusion reactors. The retention and release behaviors of hydrogen and helium in vanadium alloy may be an important issue. In the present work, 1.7 keV deuterium and 5 keV helium ions are respectively implanted into V-4Cr-4Ti and V-4Ti at room temperature. The retention and release of deuterium and helium are measured with thermal desorption spectroscopy (TDS). When the helium ion fluence is larger than 3 × 1017 He/cm2, the retained helium saturates with a value of approximately 2.5 ×1017 He/cm2. However, when the ion fluence is 1×1019 D/cm2, the hydrogen saturation in vanadium alloy does not take place. Experimental results indicates that hydrogen and helium retention in vanadium alloy may lead to serious problems and special attention should be paid when it is applied to fusion reactors.

关键词： deuterium helium vanadium alloy thermal desorption spectroscopy retention and release

Determination of the Dzyaloshinskii-Moriya interaction using pattern recognition and machine learning

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npj Computational Materials 2021年第1期7卷 198-204页

作者： Masashi Kawaguchi Kenji Tanabe Keisuke yamada Takuya Sawa Shun Hasegawa Masamitsu Hayashi Yoshinobu Nakatani Department of Physics The University of TokyoTokyo 113-0033Japan Toyota Technological Institute Nagoya 468-8511Japan Department of Chemistry and Biomolecular Science Faculty of EngineeringGifu UniversityGifu 501-1193Japan University of Electro-Communications Tokyo 182-8585Japan

Machine learning is applied to a large number of modern devices that are essential in building an energy-efficient smart *** and face recognition are among the most well-known technologies that make use of such artificial *** materials research,machine learning is adapted to predict materials with certain functionalities,an approach often referred to as materials ***,we show that machine learning can be used to extract material parameters from a single image obtained in *** Dzyaloshinskii–Moriya(DM)interaction and the magnetic anisotropy distribution of thin-film heterostructures,parameters that are critical in developing next-generation storage class magnetic memory technologies,are estimated from a magnetic domain *** simulation is used to generate thousands of random images for training and model validation.A convolutional neural network system is employed as the learning *** DM exchange constant of typical Co-based thin-film heterostructures is studied using the trained system:the estimated values are in good agreement with ***,we show that the system can independently determine the magnetic anisotropy distribution,demonstrating the potential of pattern *** approach can considerably simplify experimental processes and broaden the scope of materials research.

关键词： pattern interaction system

Quantitation of HBsAg predicts response to entecavir therapy in HBV genotype C patients

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World Journal of Gastroenterology 2012年第39期18卷 5570-5575页

作者： Etsuro Orito Kei Fujiwara Hiroshi Kanie Tesshin Ban Tomonori yamada Katsumi Hayashi Department of Gastroenterology Nagoya Daini Red Cross HospitalNagoya 466-8650Japan

AIM： To analysis the factors that predict the response to entecavir therapy in chronic hepatitis patients with hepatitis B virus （HBV） genotype C. METHODS： Fifty patients [hepatitis B e antigen （HBeAg）- negative：HBeAg-positive = 26：24] with HBV genotype C, who received nalve entecavir therapy for 〉 2 years, were analyzed. Patients who showed HBV DNA levels ≥ 3.0 log viral copies/mL after 2 years of entecavir ther- apy were designated as slow-responders, while those that showed 〈 3.0 log copies/mL were termed rapid- responders. Quantitative hepatitis B surface antigen （HBsAg） levels （qHBsAg） were determined by the Archi- tect HBsAg QT immunoassay. Hepatitis B core-related antigen was detected by enzyme immunoassay. Pre-C and Core promoter mutations were determined using by polymerase chain reaction （PCR）. Drug-resistance muta- tions were detected by the PCR-Invader method. RESULTS： At year 2, HBV DNA levels in all patients in the HBeAg-negative group were 〈 3.0 log copies/mL. In contrast, in the HBeAg-positive group, 41.7% were slow-responders, while 58.3% were rapid-responders. No entecavir-resistant mutants were detected in the slow-responders. When the pretreatment factors were compared between the slow- and rapid-responders; the median qHBsAg in the slow-responders was 4.57 log IU/mL, compared with 3.63 log IU/mL in the rapid- responders （P 〈 0.01）. When the pretreatment factors predictive of HBV DNA-negative status at year 2 in all 50 patients were analyzed, HBeAg-negative status, low HBV DNA levels, and low qHBsAg levels were signifi- cant （P 〈 0.01）. Multivariate analysis revealed that the low qHBsAg level was the most significant predictive factor （P = 0.03）. CONCLUSION： Quantitation of HBsAg could be a use- ful indicator to predict response to entecavir therapy.

关键词： Chronic hepatitis B Quantitation of hepa-titis B surface antigen Entecavir Hepatitis B virusgenotype C SIow-responders Hepatitis B core-relatedantigen Core promoter mutation Pre-C mutation