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PIV Measurements of Flows around the Wind Turbines with a Flanged-Diffuser Shroud

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Journal of Thermal Science 2008年第4期17卷 375-380页

作者： Kazuhiko Toshimitsu Koutarou Nishikawa Wataru Haruki Shinichi Oono Manabu Takao yuji Ohya Dept.of Mechanical Engineering Oita National College of Technology Kawasaki Precision Machinery Ltd. Honda Motor Co. Ltd. Machine & Electronics Co. Ltd. Dept.of Mechanical Engineering Matsue National Collage of Technology Research Institute of Applied Mechanics Kyushu University

The wind turbines with a flanged-diffuser shroud -so called ＂wind lens turbine＂- are developed as one of high performance wind turbines by Ohya et al. In order to investigate the flow characteristics and flow acceleration, the paper presents the flow velocity measurements of a long-type and a compact-type wind turbines with a flanged-diffuser shroud by particle image velocimetry. In the case of the long type wind turbine, the velocity vec- tors of the inner flow field of the diffuser for turbine blades rotating and no blades rotating are presented at Rey- nolds number, 0.9x105. Fur^thermore the flow fields between with and without rotating are compared. Through the PIV measurement results, one can realize that the turbine blades rotating affects as suppress the disturbance and the flow separation near the inner wall of the diffuser. The time average velocity vectors are made on the av- erage of the instantaneous velocity data. There are two large vortices in downstream region of the diffuser. One vortex behind the flange acts as suck in wind to the diffuser and raise the inlet flow velocity. Another large vortex appears in downstream. It might be act as blockage vortex of main flow. The large blockage vortex is not clear in the instantaneous velocity vectors, however it exists clearly in the time average flow field. The flow field around the wind turbine with a compact-type flanged-diffuser shroud is also investigated. The flow pattern behind the flange of the compact-type turbine is the same as the long-type one. It means that the effect of flow acceleration is caused by the unsteady vortices behind the flange. The comparison with CFD and PIV results of meridional time-average streamlines after the compact-type diffuser is also presented.

关键词： wind turbine PIV wind energy flanged diffuser flow visualization

Mechanics analysis of thin-walled box continuous girder with variable cross-sections in considering effect of large deflection and shear lag

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Frontiers of Structural and Civil Engineering 2009年第4期3卷 352-356页

作者： yuji CHEN Qizhi LUO Department of Civil Engineering and Architecture Foshan Science and Technology UniversityFoshan 528000China

In order to study the mechanics behavior of a thin-walled box continuous girder with variable crosssections,using potential variation theories,considering the effect of shear lag of flange’s stress and the nonlinear geometry of vertical displacement,and evolving five generalized displacements with the spline function,the large deflection problem of the thin-walled box continuous girder with variable cross-section was transformed to a nonlinear algebraic equation,which was solved using the Newton-Raphon iterative *** results of the calculation show that different shear lag warp functions to the cantilever,top and bottom plate should be taken to analyze the mechanics behavior of the thin-walled box continuous girder *** thin-walled box continuous girder with variable cross-sections has more reasonable stress state and is more adaptable for the longitudinal change of internal forces than that with equal *** effect of large deflection on the stress and displacement of the thin-walled box continuous girder with variable cross-sections depends on the values of the load.

关键词： thin-walled box girder with variable crosssections potential variational theory shear lag large deflection problem

Biomimetic Riblets Inspired by Sharkskin Denticles： Digitizing, Modeling and Flow Simulation

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Journal of Bionic Engineering 2018年第6期15卷 999-1011页

作者： Mariko Miyazaki yuji Hirai Hiroshi Moriya Masatsugu Shimomura Akihiro Miyauchi Hao Liu Hitachi Ltd. 832-2 Horiguchi Hitachinaka Ibaraki 312-0034 Japan Chitose Institute of Science and Technology 758-65 Bibi Chitose Hokkaido 066-8655 Japan Tokyo Medical Dental University 2-3-10 Kanda-Surugadai Chiyodaku Tokyo 101-0062 Japan Chiba University 1-33 Yayoi-cho Inage-ku Chiba 263-8522 Japan

While sharkskin surface roughness in terms of denticle morphology has been hypothesized but remains yet controversial to be capable of achieving turbulent flow control and drag reduction, sharkskin-inspired ＂riblets＂ have been reported to be an effective biomimetic design. Here we address an integrated study of biomimetic riblets inspired by sharkskin denticles by combining 3D digitizing and mod- eling of＂fresh＂ denticles and computational fluid dynamic modeling of turbulent flows on a rough surface with staggered denticles and hound-tooth-patterned grooves. Realistic microstructures of denticles in five shark species of Galapagos, great white, whitetip reef, blacktip reef, and hammerhead sharks were first measured and digitized in three fold：（1） 2D imaging of lubricated sharkskin in a wet state by means of a ＂nano-suit＂ technique with a Field-Emission Scanning Electron Microscope （FE-SEM）; （2） 3D structures of sharkskin denticles with a micro-focus X-ray CT; and （3） single denticles of the five shark species in a 3D manner with 3D-CAD. The denticles at mid-body location in the five species were observed to have a structure of five non-uniform-ridges （herein termed ＂non-uniform grooves＂） with Angles Of Inclination （AOI） ranging over 20° - 32°. Hydrodynamics associated with the unique five-ridge denticles were then in- vestigated through modeling turbulent flow past a denticle-staggered skin surface. We further constructed a biomimetic riblet model inspired by the non-uniform grooves and investigated the hydrodynamic effects of height-to-spacing ratios of mid-ridge and side-ridges. Our results indicate that the morphological non-uniformity in sharkskin denticles likely plays a critical role in passively controlling local turbulent flow and point to the potential of denticle-inspired biomimetic riblets for turbulent-flow control in aquatic vehicles as well as other fluid machinery.

关键词： sharkskin denticles biommetic riblets 3D digitizing computational fluid dynamics

Effects of cryogenic temperature on tensile and impact properties in a medium-entropy VCoNi alloy

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Journal of Materials Science & Technology 2021年第31期90卷 159-167页

作者： Dae Cheol Yang Yong Hee Jo yuji Ikeda Fritz Kormann Seok Su Sohn Department of Materials Science and Engineering Korea University02841 SeoulSouth Korea Metallic Materials Division Korea Institute of Materials Science51508 ChangwonSouth Korea Institute for Materials Science University of StuttgartPfaffenwaldring 5570569 StuttgartGermany Max-Planck-Institut für Eisenforschung Max-Planck-Straβe 140237 DüsseldorfGermany Department of Materials Science and Engineering Delft University of TechnologyMekelweg 22628 CD DelftThe Netherlands

Multi-principal element alloys usually exhibit outstanding strength and toughness at cryogenic temperatures,especially in CrMnFeCoNi and CrCoNi *** remarkable cryogenic properties are attributed to the occurrence of deformation twins,and it is envisaged that a reduced stacking fault energy(SFE)transforms the deformation mechanisms into advantageous properties at cryogenic temperatures.A recently reported high-strength VCoNi alloy is expected to exhibit further notable cryogenic ***,no attempt has been made to investigate the cryogenic properties in detail as well as the underlying deformation ***,the effects of cryogenic temperature on the tensile and impact properties are investigated,and the underlying mechanisms determining those properties are revealed in terms of the temperature dependence of the yield strength and deformation *** the strength and ductility were enhanced at 77 K compared to 298 K,while the Charpy impact toughness gradually decreased with *** planar dislocation glides remained unchanged at 77 K in contrast to the CrMnFeCoNi and CrCoNi alloys resulting in a relatively constant and slightly increasing SFE as the temperature decreased,which is confirmed via ab initio ***,the deformation localization near the grain boundaries at 298 K changed into a homogeneous distribution throughout the whole grains at 77 K,leading to a highly sustained strain hardening *** reduced impact toughness is directly related to the decreased plastic zone size,which is due to the reduced dislocation width and significant temperature dependence of the yield strength.

关键词： Medium-entropy alloy Cryogenic temperature Tensile property Charpy impact property Stacking fault energy

Pressure and Temperature Dependences of Elastic Properties of Grossular Garnet up to 17 GPa and 1 650 K

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Journal of Earth Science 2010年第5期21卷 782-791页

作者： Yoshio Kono Steeve Gréaux yuji Higo Hiroaki Ohfuji Tetsuo Irifune Geodynamics Research Center Ehime University JASRI 1-1-1 Mikazuki-cho Sayo-gun Hyogo 679-5198 Japan

Simultaneous ultrasonic elastic wave velocity and in situ synchrotron X-ray measurements on grossular garnet were carried out up to 17 GPa and 1 650 K. P- and S-wave vdoeities and bulk and shear modulus showed linear pressure and temperature dependence. These data yielded a pressure derivative of the bulk modulus of 4.42（7） and a shear modulus of 1.27（3）, which are in good agreement with those of garnets with variable chemical compositions. Temperature dependence of the bulk modulus of grossular （-1.36×10^-2 GPafK） is also similar to that of other garnets, while the temperature dependence of the shear modulus of grossular （-1.11×10^-2 GPa/K） is higher than those of magnesium end-member garnets and pyrolitic garnet.

关键词： elastic property grossular garnet high pressure high temperature.

Anisotropy of mechanical properties of 2297-T87 Al–Li alloy thick plates

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International Journal of Minerals,Metallurgy and Materials 2023年第11期30卷 2212-2223页

作者： yuji Bai Zhixiu Wang Bo Jiang Mengqi Li Cong Zhu Xiaotong Gu Hai Li School of Materials Science and Engineering Changzhou UniversityChangzhou 213164China Jiangsu Key Laboratory of Material Surface Science and Technology Changzhou UniversityChangzhou 213164China

The tensile properties of 2297-T87 Al–Li alloy thick plates at different thickness position and in different direction were analyzed via tensile testing,optical microscopy(OM),X-ray diffraction(XRD),scanning electron microscopy(SEM),energy dispersive spectrometry(EDS),and transmission electron microscopy(TEM).Results indicated that the ultimate tensile strength(UTS)and yield strength(YS)of the alloy decreased firstly and then increased from the 1/8T position to the 1/2T position,whereas elongation to failure(Ef)decreased gradually such that its value along the rolling direction(RD)was higher than those along the transverse direction(TD)at the same thickness *** the 1/8T position to the 3/8T position of the alloy,the UTS and YS along the TD were higher than those along the *** the 1/2T position of the alloy,the UTS,YS,and Ef along the RD were the highest,whereas those along the normal direction(ND)were the *** observations further revealed that the anisotropy of tensile properties was related to grain morphology,crystal texture,second-phase particles,and Li atom segregation.

关键词： 2297 alloy thick plate tensile properties anisotropy grain morphology second-phase particles

Phonon broadening in high entropy alloys

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npj Computational Materials 2017年第1期3卷 154-162页

作者： Fritz Kormann yuji Ikeda Blazej Grabowski Marcel H.F.Sluiter Materials Science and Engineering Delft University of Technology2628 CD DelftThe Netherlands Center for Elements Strategy Initiative for Structural Materials Kyoto UniversityKyoto 606-8501Japan Computationals Materials Design Max-Planck-Institut fur Eisenforschung GmbH40237 DusseldorfGermany

Refractory high entropy alloys feature outstanding properties making them a promising materials class for next-generation hightemperature *** high temperatures,materials properties are strongly affected by lattice vibrations(phonons).Phonons critically influence thermal stability,thermodynamic and elastic properties,as well as thermal *** contrast to perfect crystals and ordered alloys,the inherently present mass and force constant fluctuations in multi-component random alloys(high entropy alloys)can induce significant phonon scattering and *** their importance,phonon scattering and broadening have so far only scarcely been investigated for high entropy *** tackle this challenge from a theoretical perspective and employ ab initio calculations to systematically study the impact of force constant and mass fluctuations on the phonon spectral functions of 12 body-centered cubic random alloys,from binaries up to 5-component high entropy alloys,addressing the key question of how chemical complexity impacts *** find that it is crucial to include both mass and force constant *** one or the other is neglected,qualitatively wrong results can be obtained such as artificial phonon band *** analyze how the results obtained for the phonons translate into thermodynamically integrated quantities,specifically the vibrational *** in the vibrational entropy with increasing the number of elements can be as large as changes in the configurational entropy and are thus important for phase stability *** set of studied alloys includes MoTa,MoTaNb,MoTaNbW,MoTaNbWV,VW,VWNb,VWTa,VWNbTa,VTaNbTi,VWNbTaTi,HfZrNb,HfMoTaTiZr.

关键词： alloys entropy high

Small-for-size syndrome in liver transplantation:Definition,pathophysiology and management

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Hepatobiliary & Pancreatic Diseases International 2020年第4期19卷 334-341页

作者： Yuichi Masuda Kazuki Yoshizawa Yasunari Ohno Atsuyoshi Mita Akira Shimizu yuji Soejima Division of Gastroenterological Hepato-Biliary-PancreaticTransplantation and Pediatric SurgeryDepartment of SurgeryShinshu University School of Medicine3-1-1 AsahiMatsumotoNaganoJapan

Background:Since the first success in an adult patient,living donor liver transplantation(LDLT)has become an universally used ***-for-size syndrome(SFSS)is a well-known complication after partial LT,especially in cases of adult-to-adult *** definition of SFSS slightly varies among transplant *** use of a partial liver graft has risks of SFSS *** portal vein(PV)hypertension and PV hyper-perfusion after LT were identified as the main ***,various approaches were explored to modulate PV flow and decrease PV pressure in order to alleviate this ***,the definition,clinical symptoms,pathophysiology,basic research,as well as preventive and treatment strategies for SFSS are reviewed based on an extensive review of the literature and on our own *** sources:The articles were collected through PubMed using search terms“liver transplantation”,“living donor liver transplantation”,“living liver donation”,“partial graft”,“small-for-size graft”,“small-forsize syndrome”,“graft volume”,“remnant liver”,“standard liver volume”,“graft to recipient body weight ratio”,“sarcopenia”,“porcine”,“swine”,and“rat”.English publications published before March 31,2020 were included in this ***:Many transplant surgeons performed PV flow modulation,including portocaval shunt,splenic artery ligation and *** these techniques,patient outcome has been improved even when using a"small"*** factors,such as preoperative recipients’nutritional and skeletal muscle status,graft congestion,and donor factors,were also identified as risk factors which all have been addressed using various ***:The surgical approach controlling PV flow and pressure could help to prevent SFSS especially in severely ill *** the absence of efficacious medications to resolve SFSS,conservative treatments,including aggressive fluid balance correction for massive ascites,anti-microbiological therapy t

关键词： Liver transplantation Living donor liver transplantation Small-for-size graft Small-for-size syndrome

Electrophilic Halogen Reagents-mediated Halogenation: Synthesis of Halogenated Dihydro-1,3-oxazine Derivatives

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Chemical Research in Chinese Universities 2023年第6期39卷 933-947页

作者： QI Liang QIN yuji WANG Xueqing CHAI Hongli ZHU Weiwei ZHOU Yifeng Department of Pharmacy College of Life SciencesChina Jiliang UniversityHangzhou 310018P.R.China School of Pharmaceutical Sciences Sun Yat-sen UniversityGuangzhou 510006P.R.China School of Basic Medical Science Lanzhou UniversityLanzhou 730000P.R.China

Halogenation of N-cinnamylbenzamides and N-[(2H-chromen-3-yl)methyl]benzamides using electrophilic halogen source was *** halogenated dihydro-1,3-oxazine derivatives(45 examples)were synthesized in high to excellent yields(up to 98%yields),as well as halogenated dihydrochromeno-1,3-oxazine derivatives(56 examples,up to 96%yields).The properties of mild conditions,metal-free and high efficiency of the reaction made it a promising strategy in future applications for the construction of carbon-halogen(fluorine,F;chlorine,Cl;bromine,Br;iodine,I)bond and 1,3-oxazine derivatives.

关键词： Carbon halogen bond 1 3-Oxazine Heterocyclization