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Value of Charpy impact test results with sub-and half-size specimens extracted from overage steel bridge members

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China Welding 2024年第3期33卷 8-13页

作者： hirohata Mikihito Department of Civil Engineering Graduate School of EngineeringOsaka UniversitySuita 565-0871Japan

For the maintenance of steel bridges,the mechanical properties of steel used in the bridges must be *** enough dimensions of specimens cannot be extracted from the actual members,miniaturized specimens are used for *** the case of the Charpy impact test,sub-and half-size specimens are specified instead of full-size specimens of which the thickness is 10 *** value of absorbed energy and energy transient temperature obtained by Charpy impact tests with sub-size and half-size specimens were investigated from the viewpoint of maintenance of bridges in this *** absorbed energy was not in proportion to the thickness of specimens of steel used in the actual overage *** tendency of energy transient temperature obtained by thin specimens of the overage steel differed from that of the present steel.A method for evaluating the performance against brittle fracture occurrence based on the WES3003 criterion was *** results show the significance of evaluation based on the energy transient temperature for reasonable maintenance of bridges.

关键词： steel bridge maintenance brittle fracture Charpy impact test overage steel

Weldability of steel used in an aged bridge

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China Welding 2024年第3期33卷 33-38页

作者： hirohata Mikihito Department of Civil Engineering Graduate School of EngineeringOsaka UniversitySuita 565-0871Japan

A series of experiments was performed to investigate the weldability of steel used in an aged bridge.A steel material used in an aged railway bridge constructed in 1912 was extracted for this *** chemical compositions of this steel were suitable for ***,the aged steel contained much *** welded joints were fabricated with this aged *** defects or cracks were not observed in the *** Vickers hardness test on the welded part did not confirm extreme hardening or *** yielding by the static tensile test,the cruciform joints were fractured at the welded *** of the specimens was fractured in the middle of the thickness of the aged *** Sulfur contained in the aged steel might cause this type of *** results show that there may be a risk of brittle fracture not only from the welded part but also from the base *** chemical compositions of aged steel must be analyzed when repair welding is applied to the steel.

关键词： aged steel bridge repair welding chemical compositions weld defect brittle fracture

Exercise,microglia,and beyond–workout to communicate with microglia

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Neural Regeneration Research 2020年第11期15卷 2029-2030页

作者： Megumi Andoh ryuta Koyama Laboratory of Chemical Pharmacology Graduate School of Pharmaceutical SciencesThe University of TokyoBunkyo-kuTokyoJapan

Microglia are brain-resident immune cells that use their ramified processes to survey the brain *** maintain brain homeostasis by mediating immune responses through cytokine release,phagocytosing pathogens and protein aggregation(Salter et al.,2017).Furthermore,in both healthy and disease states,microglia interacting with neurons regulate synaptic formation,elimination and plasticity(Salter et al.,2017).It is thought that these functions may be altered by environmental stimuli such as lifestyle,stress,infection and air pollution,the effects of which may result in brain dysfunction and the development of neurodegenerative diseases(Branchi et al.,2014;Hanamsagar et al.,2017).

关键词： al. homeostasis diseases

An Experimental Study on Aerodynamic Sound Generated from Wake Interaction of Circular Cylinder and Airfoil with Attack Angle in Tandem

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Journal of Thermal Science 2008年第3期17卷 212-217页

作者： Mizue MUNEKATA ryuta KOSHIISHI Hiroyuki YOSHIKAWA Hideki OHBA Department of Mechanical System Engineering

In our previous study, the effects of the interval between the cylinder and the airfoil on the aerodynamic sound were investigated and compared with the cases of single circular and single airfoil. In this study, the effects of the attack angle of the airfoil located downstream on the characteristics of aerodynamic sound and the wake structure are investigated at a given interval between the cylinder and the airfoil. It is found that the sound pressure level of DFN and the peak frequency decrease with increasing attack angle of airfoil because of the diffusive wake structure due to the increased back pressure of circular cylinder, which is caused by the blocking effect of airfoil. It is shown that the sound sources are corresponded to the attack points of shedding vortex form the upstream circular cylinder to the downstream airfoil. We conclude that the pressure fluctuation at the airfoil surface effects on the sound pressure level, from the flow visualizations and the exploration test of sound source.

关键词： aerodynamic sound wake interaction circular cylinder airfoil Karman's vortex flow visualization

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

Nanometer-Order Contouring Control in a Feed Drive System Using Linear Ball Guides by Applying a Combination of Modified Disturbance Observer and Repetitive Control

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Nanomanufacturing and Metrology 2021年第2期4卷 118-129页

作者： Tomofumi Ohashi Hitoshi Shibata Shigeru Futami ryuta Sato THK Co. Ltd.4-9-16 HigashikoujiyaOta-kuTokyoJapan Advanced Manufacturing Systems Laboratory Kobe University2-1 RokkodaiNada-kuKobeHyogoJapan

This paper proposes a quadrant glitch compensation method to achieve nanometer-level accuracy of contouring control for a feed drive system using linear ball *** proposed method is a combination of a modified disturbance observer(“disturbance suppressor”)and an improved repetitive control *** motion tests with 1 mm amplitude and 0.1 Hz driving frequency were conducted using a single-axis feed drive system to verify the quadrant glitch compensation ability of this ***,the repeatability of the quadrant glitches in the experimental system was verified,which is the most important characteristic required for compensation via repetitive ***,by applying the combination of disturbance suppressor and conventional repetitive control,the amplitudes of the quadrant glitches were decreased to less than 1 nm;in other words,the ratio of the magnitude of the quadrant glitch to the amplitude of the position reference was less than 1/1,000,***,for both compensation schemes mentioned before,vibrations were generated when the feed speed ***,the amplitudes increased with the number of *** reason for the vibrations was identified as the repetitive control *** suppress these vibrations,the repetitive control was applied only to narrowed regimes near the quadrant ***,the maximum contouring error was decreased to 2 *** addition,the nonlinear spring behavior of the linear ball guides was confirmed to affect the stability of the control systems.

关键词： Quadrant glitch Feed drive system Contouring control Repetitive control Disturbance observer Nonlinear spring behavior

A case of hepatic angiomyolipoma difficult to distinguish from hepatocellular carcinoma

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World Journal of Gastroenterology 2009年第23期15卷 2930-2932页

作者： Masahiro Takahara Yasuhiro Miyake Kazuyuki Matsumoto Daisuke Kawai Eisuke Kaji Tatsuya Toyokawa Morihito Nakatsu Masaharu Ando Mamoru hirohata Department of Internal Medicine Mitoyo General Hospital Kagawa 769-1695 Japan Department of Molecular Hepatology and Department of Gastroenterology & Hepatology University Graduate School of Medicine Dentistry and Pharmaceutical Sciences Okayama 700-8558 Japan

We report a case of hepatic angiomyolipoma with uncommon clinical features. A 56-year-old man presented with a hepatic tumor in the caudate lobe. The tumor was hypoechoic on ultrasonography, showed early-phase hyperattenuation on enhanced computed tomography and did not absorb iron on superparamagnetic iron oxide-enhanced magnetic resonance imaging. Hepatocellular carcinoma was highly suspected, and the patient underwent hepatic resection. Histologically, the tumor was mainly composed of smooth muscle cells and contained small amounts of adipose cells and blood vessels. On immunohistochemical staining, the smooth muscle cells were positive for a melanocytic cell-specific monoclonal antibody. In cases with uncommon features of angiomyolipoma, it is quite difficult to distinguish angiomyolipoma from hepatocellular carcinoma.

关键词： Adipose cell Hepatic angiomyolipoma Hepatocellular carcinoma HMB-45 Smooth muscle cell

Deuterium Retention and Physical Sputtering of Low Activation Ferritic Steel

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Plasma Science and Technology 2005年第2期7卷 2737-2740页

作者： T.Hino K.Yamaguchi Y.Yamauchi Y.hirohata K.Tsuzuki Y.Kusama Department of Nuclear Engineering Hokkaido University Sapporo060-8628 JapanDepartment of Nuclear Engineering Hokkaido UniversitySapporo060-8628 JapanDepartment of Nuclear Engineering Hokkaido UniversitySapporo060-8628 JapanDepartment of Nuclear Engineering Hokkaido UniversitySapporo060-8628 JapanJapan Atomic Energy Research Institute NakaIbaraki-ken311-0193 JapanJapan Atomic Energy Research Institute NakaIbaraki-ken311-0193 Japan

Low activation materials have to be developed toward fusion demonstrationreactors. Ferritic steel, vanadium alloy and SiC/SiC composite are candidate materials of the firstwall, vacuum vessel and blanket components, respectively. Although changes of mechanical-thermalproperties owing to neutron irradiation have been investigated so far, there is little data for theplasma material interactions, such as fuel hydrogen retention and erosion. In the present study,deuterium retention and physical sputtering of low activation ferritic steel, F82H, wereinvestigated by using deuterium ion irradiation apparatus. After a ferritic steel sample wasirradiated by 1.7 keV D^+ ions, the weight loss was measured to obtain the physical sputteringyield. The sputtering yield was 0.04, comparable to that of stainless steel. In order to obtain theretained amount of deuterium, technique of thermal desorption spectroscopy (TDS) was employed to theirradiated sample. The retained deuterium desorbed at temperature ranging from 450 K to 700 K, inthe forms of DHO, D_2, D_2O and hydrocarbons. Hence, the deuterium retained can be reduced by bakingwith a relatively low temperature. The fluence dependence of retained amount of deuterium wasmeasured by changing the ion fluence. In the ferritic steel without mechanical polish, the retainedamount was large even when the fluence was low. In such a case, a large amount of deuterium wastrapped in the surface oxide layer containing O and C. When the fluence was large, the thickness ofsurface oxide layer was reduced by the ion sputtering, and then the retained amount in the oxidelayer decreased. In the case of a high fluence, the retained amount of deuterium became comparableto that of ferritic steel with mechanical polish or SS 316 L, and one order of magnitude smallerthan that of graphite. When the ferritic steel is used, it is required to remove the surface oxidelayer for reduction of fuel hydrogen retention. Ferritic steel sample was exposed to the envi

关键词： ferritic steel fuel hydrogen retention sputtering yield first wall fusionreactor

High Effective FE Simulation Methods for Deformation and Residual Stress by Butt Welding of Thin Steel Plates

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Engineering（科研） 2014年第9期6卷 507-515页

作者： Mikihito hirohata Yoshito Itoh Graduate School of Engineering Nagoya University Nagoya Japan

In order to propose high effective simulation using finite element method (FEM) for predicting deformation and residual stress generated by one pass butt welding, a series of numerical analyses were carried out. By idealizing the movement of heat source (the instantaneous heat input method), the tendency of welding out-of-plane deformation and the residual stress distribution could be predicted. The computing time was around 9% of that by the precise model with considering the movement of heat source. On the other hand, applicability of two dimensional shell elements instead of generally used three dimensional solid elements was examined. The heat input model with considering the temperature distribution in the thickness direction was proposed for the simulation by using the shell elements. It was confirmed that the welding out-of-plane deformation and residual stress could be predicted with high accuracy by the model with shell elements and the distributed heat input methods. The computing time was around 8% of that by the precise model with solid elements.

关键词： Welding Deformation Residual Stress Butt Welding FEM Shell Element