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Open Journal of metal 2014年第2期4卷 31-39页

作者： Y.-C. Kim m. hirohata K. Inose Graduate School of Engineering Nagoya University Nagoya Japan IHI Corporation Yokohama Japan Osaka University Osaka Japan

A series of experiments was carried out so as to elucidate the effect of the phase transformation in the cooling process on welding distortion and residual stress generated by laser beam welding (LBW) and laser-arc hybrid welding (HYBW) on the high strength steel (HT780). Then, the experiments were simulated by 3D thermal elasticplastic analysis with FEm (Finite Element method) which was performed with using the idealized mechanical properties considering the transformation superplasticity. From the results, the effects of the phase transformation on welding distortion and residual stress generated by LBW and HYBW were elucidated. Furthermore, the generality of the idealization of the mechanical properties was verified.

关键词： Welding Distortion Residual Stress Laser Beam Welding Laser-Arc Hybrid Welding Phase Transformation FEm

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

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

Compressive Behavior of Steel members Reinforced by Patch Plate with Welding and Bonding

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Open Journal of Civil Engineering 2018年第4期8卷 341-357页

作者： Xiaoyang Liu mikihito hirohata Department of Civil and Environmental Engineering Graduate School of Engineering Nagoya University Nagoya Japan Department of Civil Engineering Division of Global Architecture Graduate School of Engineering Osaka University Suita Japan

Repair and reinformcement of aged civil steel structures is one of the important issues for maintaining and using them for a long term. For repair and reinforcement of deteriorated civil steel structures due to fatigue and corrosion, patch plate reinforcement is widely applied. Bolting is generally used because of easy quality control and many construction achievements. However, bolting has downsides including holes made and weight increase. Welding is considered to overcome these demerits but in reality the application of welding is unsatisfactory due to the possibility of fatigue crack occurring from the welded part. In this study, a patch plate strengthening system of welded joint assisted with bonding has been proposed. The compressive behaviors of weld-bond jointed specimen were investigated by a series of experiments and FE analysis. It was confirmed that use of welding and bonding was effective to enhance compressive strength of specimen, due to better load-carrying capacity of patch plate compared with sole use of welding.

关键词： Welding Bonding Compressive Behavior Patch Plate Reinforcement

A combination treatment of entecavir and early-phase corticosteroid in severe exacerbation of chronic hepatitis B

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World Journal of Gastroenterology 2009年第13期15卷 1650-1652页

作者： Kazuyuki matsumoto Yasuhiro miyake Hirokazu miyatake masahiro Takahara Takayuki Imada Satoru Yagi Tatsuya Toyokawa morihito Nakatsu masaharu Ando mamoru hirohata Department of Internal medicine Mitoyo General Hospital Department of molecular Hepatology Okayama University Graduate School of MedicineDentistry and Pharmaceutical Sciences

Of patients with severe exacerbation of chronic hepatitis B accompanied by jaundice and coagulopathy,20%-30%have a fatal *** this report,we describe 2 cases of severe exacerbation of chronic hepatitis B with jaundice and coagulopathy who were successfully treated with a combination of entecavir and *** both cases,rapid reductions in serum hepatitis B virus(HBV)-DNA levels were observed,and corticosteroid was stopped after serum HBV-DNA levels became *** treatment was ***,entecavir treatment reduced serum HBV-DNA levels rapidly,although the improvement in liver function was delayed by a few *** this time lag,liver cell injury continued and the disease *** suppressed the excessive host immune response and was useful for stopping progressive deterioration.A combination of entecavir and early-phase corticosteroid may be a useful treatment in severe exacerbation of chronic hepatitis B.

关键词： Acute exacerbation Chronic hepatitis B Corticosteroid Entecavir Hepatitis B virus Hepaticcoma

Effect of PWHT with Sheet-Type Ceramic Heater on Compressive Behaviors of Non-Stiffened Welded Steel Box Columns

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World Journal of Engineering and Technology 2018年第1期6卷 50-67页

作者： may Phyo Aung mikihito hirohata Graduate School of Engineering Nagoya University Nagoya Japan

A series of fundamental experimental investigation was conducted in order to examine the effect of PWHT by sheet-type ceramic heater on the residual stress, deformation and compressive behavior of non-stiffened welded box columns. The sheet-type ceramic heater was able to control the required temperature history for PWHT with high accuracy. The welding-induced tensile and compressive residual stresses of the specimens were reduced by 90% and 76% respectively with PWHT. Besides, PWHT could reduce the welding-induced out-of-plane deformation by 22%. It was revealed that the PWHT specimens had a slight higher stiffness than the As-welded specimens when applying monotonic static compressive load on both As-welded and PWHT specimens. They could also enhance the ultimate compressive load capacity about 32% of that of the As-welded specimens. The effectiveness of PWHT with the sheet-type ceramic heater could be confirmed.

关键词： Residual Stress Out-of-Plane Deformation PWHT Sheet-Type Ceramic Heater Welded Box Column

FSm-monitoring of Fatigue Crack in Lattice-Stiffened Steel Plate Deck for Bridge Structures

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Journal of mechanics Engineering and Automation 2013年第9期3卷 578-585页

作者： You-Chul Kim mikihito hirohata Kyong-Ho Chang Osaka University Osaka 532-0003 Japan Department of Civil Engineering Graduate School of Engineering Nagoya University Nagoya 464-8603 Japan Department of Civil and Environmental Engineering Chung-Ang University Seoul 156-756 Korea

For elucidating applicability of FSm （field signature method） on detection of fatigue crack initiation and monitoring of its propagation, a series of fatigue tests on steel plate decks （4,625 × 2,250 mm^2） stiffened in lattice-shape by longitudinal and lateral ribs was carried out by using a wheel load traveling test machine. The fatigue crack was observed by visual inspection at the weld toe between the deck plate and the longitudinal rib when the number of wheel load traveling repetition was around 210 thousands. The response of FSm-monitoring, which was the potential difference change between the sensing pins （pair）, became clear when the number of the repetition was around 190 thousands. The fatigue crack initiation could be detected by FSm considerably earlier than visual inspection. The fatigue crack propagation such as the direction could also be monitored even though the distance of the sensing pins was extended to 230 mm. On the other hand, the electric field analysis for the virgin situation without any cracks was carried out. The results of analysis indicated that 60 mm length of crack which could not be confirmed by visual inspection could be detected by FSm.

关键词： Fatigue crack steel plate deck non-destructive inspection monitoring FSm.

A Proposal of Deciding Fatigue Strength in Bending Fatigue Test

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Journal of mechanics Engineering and Automation 2014年第2期4卷 158-164页

作者： You-Chul Kim mikihito hirohata Geoffrey mutyaba Hun-Sur Bang Osaka University Osaka 567-0047 Japan Graduate School of Engineering Nagoya University Aichi 464-8603 Japan Graduate School of Engineering Osaka University Osaka 567-0047 Japan Department of Naval Architecture and Ocean Engineering Chosun University Gwangju 501-759 Korea

Generally, the fatigue crack is initiated and then it is propagated toward the welding direction and the thickness direction. Finally, the joints lose the resistance to the external force. At present, as there is no deciding method of the fatigue strength （fatigue life）, this paper proposed it from the result obtained by bending test for fillet welded joints. Judging initiation of the fatigue crack from the measured value of strain gages, there was a possibility that the fatigue crack occurred at both sides of fillet welded joints. However, this was a different result from that of macrograph of cross section. On the other hand, the results obtained by FSm （field signature method） coincided with the result of macrograph of cross section. For the initial state, potential difference obtained by the electrostatic analysis based on FEm （finite element method） and that by FSm was accurately coincided. After confirming validity of the crack model for analysis, the crack model was specified by reproducing the propagating process of crack accurately through trial and error. It was concluded that the state which could not resist to the external force was regarded as fatigue strength based on equivalent stress obtained by elastic stress analysis for specified crack model. From the experimental result, it was proposed that 90% of repetition number corresponding to the state which could not resist to the external force （at the finish of the test） was regarded as fatigue strength （fatigue life） in consideration of safety and as the first approximation.

关键词： Fatigue crack fatigue strength fatigue life crack initiation/propagation potential difference FSm.