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Misorientation dependent thermal condition-solute field cooperative effect on competitive grain growth in the converging case during directional solidification of a nickel-base superalloy

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Journal of Materials Science & technology 2022年第1期96卷 151-159页

作者： X.B.Meng J.G.Li C.N.Jing J.D.Liu S.y.Ma J.J.Liang C.W.Zhang M.Wang B.t.tang t.Lin J.L.Chen X.L.Zhang Q.Li School of Mechanical and Automotive Engineering Qilu University of Technology(Shandong Academy of Sciences)Jinan 250353China Institute of Metal Research Chinese Academy of SciencesShenyang110016China School of Materials Science and Engineering Shandong Jianzhu UniversityJinan 250014China AECC Shenyang Liming Aero-Engine Co. LTD.Shenyang110043China College of Material Science and Engineering North Minzu UniversityYinchuan 750021China Faculty of electro-mechanical information Weifang University of Science and TechnologyShouguang262700China

Nowadays,thermal condition and solute field are considered as the potential dominant factors controlling competitive grain growth during directional solidification ***,the controlling modes and critical conditions of competitive grain growth have been drastically debated over the past two *** this work,thermal condition and solute field are combined to study the competitive grain growth in the converging case by experimental observation and numerical simulation of bicrystal *** find the competitive grain growth is controlled by the cooperative effect of thermal condition and solute field,and the controlling modes are related to the bicrystal misorientation between favorably and unfavorably oriented *** the unfavorably oriented grain is low misoriented,unfavorably oriented grain dominates grain selection,and the competitive grain growth performs as solute field ***,with the increase of unfavorably oriented grain’s misorientation,the grain selection converts into favorably oriented grain domination,and the competitive grain growth changes to thermal condition *** explain these abnormal transformation phenomena,we propose a misorientation dependent thermal condition-solute field cooperative domination model and identify the critical conditions by a critical misorientation(θ_(cm)).According to dynamic equation of dendrite growth,we calculate the critical misorientationθ;to prove this *** theoretical calculation results agree well with the experimental results.

关键词： Competitive grain growth Cooperative effect thermal condition Solute field Critical misorientation Unusual overgrowth Abnormal transformation

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Effect of forced-air cooling on the microstructure and age-hardening response of extruded Mg-Gd-y-Zn-Zr alloy full with LPSO lamella

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Journal of Materials Science & technology 2021年第14期73卷 66-75页

作者： S.Z.Wu t.Nakata G.Z.tang C.Xu X.J.Wang X.W.Li X.G.Qiao M.y.Zheng L.Geng S.Kamado G.H.Fan School of Materials Science and Engineering Harbin Institute of TechnologyHarbin 150001China Research Center for Advanced Magnesium technology Nagaoka University of TechnologyNagaoka 940-2188Japan School of Material Science and Engineering Harbin University of Science and TechnologyHarbin 150040China Key Laboratory for Light-weight Materials Nanjing Tech UniversityNanjing 211816China

the homogenized Mg-8.2 Gd-3.8 y-1.0 Zn-0.4 Zr(wt.%)alloy full of plate-shaped long period stacking ordered(LPSO)phases was hot extruded in the atmosphere and cooled by the forced-air,then the effect of forced-air cooling on the microstructure and age-hardening response of the alloy was investigated in this *** results show that in comparison with the extruded sample cooling in the atmosphere,the forced-air cooling restricts dynamic recrystallization(DRX)and brings about finer dynamic recrystallized(DRXed)grain size,stronger basal texture and higher dislocation ***,the forced-air cooling promotes the dynamic precipitation in the DRXed regions and facilitates formation of plate-shaped LPSO phases andγ’phases with smaller interspacing in the unrecrystallized(un DRXed)regions,then slightly restricts the precipitation ofβphases during *** peak-ageing treatment,the extruded sample with forced-air cooling shows superior tensile properties with a tensile yield strength of 439 MPa,an ultimate tensile strength of 493 MPa,and elongation to failure of 18.6%.

关键词： Mg-RE alloy LPSO phase Dynamic recrystallization Precipitation Mechanical properties

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Predicted trends of soil erosion and sediment yield from future land use and climate change scenarios in the Lancang-Mekong River by using the modified RUSLE model

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International Soil and Water Conservation Research 2020年第3期8卷 213-227页

作者： Pavisorn Chuenchum Mengzhen Xu Wenzhe tang Institute of Hydraulic Structures Engineering and Project Management and State Key Laboratory of Hydroscience EngineeringTsinghua UniversityBeijing100084PR China River Research Institute And State Key Laboratory of Hydroscience EngineeringTsinghua UniversityBeijing100084PR China

Soil erosion and sediments in the Lancang-Mekong River Basin as a result of climate change and changes in land use pose a threat to the existence of the riparian people,biodiversity and *** study seeks to assess the annual soil erosion in terms of spatial distribution and the trends of sediment yield with the climate and land changes in future scenarios in 2030 and 2040 through the modified RUSLE *** lands were simulated by using the MLP artificial neural network and the Markov chain *** future climate was examined by using the Max Planck Institute model,which showed a corrected bias and downscaled grid size under the Representative Concentration Pathways(RCPs).the simulated land use indicated that the forest areas were converted mostly to agricultural lands and urban *** the future,the average rainfall under all RCP scenarios is higher than that from the historical *** R and C factors changed constantly,thereby affecting the soil erosion rate and sediment *** maximum erosion was estimated at approximately 21,000 and 21,725 t/km2/y under RCP8.5 in both ***,the results of sediment yield in 2030 and 2040 under RCP scenarios were much higher when compared to historical sediment data around 66.3%and 71.2%,***'s plateau,some parts of Cambodia and Laos PDR and the Mekong Delta are vulnerable to increase soil erosion and sediment *** to address these issues need to be planned to prepare and mitigate the possible effects,especially the loss of storage capacity in dams.

关键词： Soil erosion Sediment Land use change Climate change RUSLE

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Petrogenesis and tectonic implications of the Early Cretaceous Dagushan adakitic porphyries in the Anshan area,North China Craton

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Acta Geochimica 2022年第1期41卷 24-38页

作者： Xiaohui Sun Haoshu tang yan Luan Key Laboratory of Western China’s Mineral Resources and Geological Engineering MOESchool of Earth Science and ResourcesChang’an UniversityXi'an 710054China State Key Laboratory of Ore Deposit Geochemistry Institute of GeochemistryChinese Academy of SciencesGuiyang 550081China

the eastern part of the North China Craton suffered significant lithospheric thinning since the Mesozoic,and petrogenesis of the Dagushan adakitic diorite porphyries provides an excellent opportunity to investigate the lithospheric thinning mechanism and geodynamic *** zircon LA-ICP-MS U–Pb geochronology reveals that the representative Dagushan adakitic porphyry was formed at 120.5±0.5 *** Dagushan diorite porphyries are characterized by the relatively high contents of SiO_(2)(64.25–65.70 wt%),Al_(2) O_(3)(15.00–15.38 wt%),Sr(333–491 ppm),low contents of y(6.50–10.3 ppm),and yb(0.57–0.85 ppm),and resultant high Sr/y(47–57)and La/yb(37–55)ratios,exhibiting geochemical characteristics of typical ***,the relatively high Mg O contents(MgO=2.23–2.29 wt%)and Mg numbers(Mg^(#)-=54–56)of the Dagushan adakitic rocks imply that the pristine adakitic magma interacted with mantle ***,the zircon Hf isotopic signatures(εHf(t)=-19.0 to-28.0;tDM2=2378–2944 Ma)suggest an ancient lower crustal ***,it is proposed that the Dagushan adakitic rock was probably generated by partial melting of delaminated lower crust which was triggered by the tan-Lu Fault Zone,and the interaction of pristine adakitic magma with mantle peridotite during the ascent finally generated the Dagushan high Mg^(#)adakitic *** is suggested that delamination was an important mechanism for lithospheric thinning of the NCC.

关键词： Diorite porphyry Adakite Lower crust Delamination NCC

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Studies of the 2α and 3α channels of the ^(12)C+^(12)C reaction in the range of E_(c.m.)=8.9 MeV to 21 MeV using the active target time Projection Chamber

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Chinese Physics C 2022年第10期46卷 116-125页

作者： X.y.Wang N.t.Zhang Z.C.Zhang C.G.Lu t.L.Pu J.L.Zhang L.M.Duan B.S.Gao K.A.Li y.t.Li y.Qian L.H.Ru B.Wang X.D.Xu H.y.Zhao W.P.Lin Z.W.Cai B.F.Ji Q.t.Li J.y.Xu X.D.tang Joint department for nuclear physics Institute of Modern Physics and Lanzhou UniversityChinese Academy of SciencesLanzhou 730000China Institute of Modern Physics Chinese Academy of SciencesLanzhou 730000China School of Nuclear Science and technology Lanzhou UniversityLanzhou 730000China School of Nuclear Science and technology University of Chinese Academy of SciencesBeijing 100049China Key Laboratory of Radiation Physics and technology of the Ministry of Education Institute of Nuclear Science and TechnologySichuan UniversityChengdu 610064China School of Physics and State Key Laboratory of Nuclear Physics and technology Peking UniversityBeijing 100871China

the ^(12)C+^(12)C fusion reaction was studied in the range of E_(c.m.)=8.9 to 21 MeV using the active-target time Projection *** full information on all tracks of the reaction products,cross sections of the^(12)C(^(12)C,^(8)Be)^(16)O_(g.s.)channel and the ^(12)C(^(12)C,3a)^(12)C channel could be measured down to the level of a few *** ^(12)C(^(12)C,^(8)Be)^(16)O_(g.s.)reaction channel was determined to be 10_(-8)^(+24) mb at E_(c.m.)=11.1 MeV,supporting the direct a transfer reaction *** ^(12)C(^(12)C,3α)^(12)C reaction channel was studied for the first time using an exclusive *** result does not confirm the anomaly behavior reported in the previous inclusive measurement by Kolata et al.[***.C 21,579(1980)].Our comparisons with statistical model calculations suggest that the 3 a channel is dominated by the fusion evaporation process at E_(c.m.)>19 *** additional contribution of the 3 a channel increases the fusion reaction cross section by 10% at energies above 20 *** also find that an additional reaction mechanism is needed to explain the measured cross section at E_(c.m.)t which point the statistical model prediction vanishes.

关键词： fusion cross section Coulomb barrier time Projection Chamber active target

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Enhancing strength and creep resistance of Mg-Gd-y-Zn-Zr alloy by substituting Mn for Zr

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Journal of Magnesium and Alloys 2019年第3期7卷 388-399页

作者： C.Xu t.Nakata G.H.Fan X.W.Li G.Z.tang S.Kamado School of Materials Science and Engineering Harbin Institute of TechnologyHarbin 150001PR China Department of Mechanical Engineering Nagaoka University of TechnologyNagaoka 940-2188Japan School of Material Science and Engineering Harbin University of Science and TechnologyHarbin 150040PR China

the age-hardening behavior and mechanical properties of the extruded Mg-2Gd-1.2y-0.5Zn(at.%)alloy with Zr or Mn additions were *** results show that Mn added alloy exhibits more remarkable age-hardening response than Zr added alloy,which is attributed to the fact that partitioning of Mn into the β'phases,β'precipitates and long period stacking ordered(LPSO)phases leads to the decrement in(G d+y)concentrations in the second phases,facilitating the precipitation during aging *** peak-aged alloys show bimodal microstructure comprising the fine DRXed grains with nano-sized β phases pinned at DRXed grain boundaries as well as coarse worked grains with strong fiber *** strength and good thermal stability were obtained in both peak-aged Mn and Zr added *** the peak-aged Mn added alloy shows higher strength and superior creep resistance due to its denser β'precipitates,thin LPSO phases and γ'precipitates and higher area fraction of worked grains with strong fiber *** 0.2% tensile proof stress and ultimate tensile strength of peak-aged Mn added alloy reach up to 454 MPa and 508 MPa,respectively,with elongation of 3.2%at room *** minimum creep rate of the peak-aged Mn added alloy at 250℃/150 MPa is 2.4 × 10^-8 s^-1,which is superior than previously reported extruded Mg-Gd based alloys.

关键词： Magnesium alloys Rare earth(RE) Precipitation Mechanical properties Creep resistance

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Design of flexible inorganic thermoelectric devices for decrease of heat loss

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Nano Research 2021年第7期14卷 2090-2104页

作者： Defang Ding Fengming Sun Fan Xia Zhiyong tang Engineering Research Center of Nano-Geomaterials of Ministry of Education Faculty of Materials Science and ChemistryChina University of Geosciences(CUG)388 Lumo RoadWuhan430074China CAS key laboratory of Nanosystem and Hierarchical Fabrication CAS Center for Excellence in NanoscienceNational Center for Nanoscience and TechnologyNo.11BeiyitiaoZhongguancunBeijing100190China University of Chinese Academy of Sciences 19 A Yuquan RdShijingshan DistrictBeijing100049China

thermoelectric(tE)devices can realize the conversion of heat energy and electrical power based on Seebeck effect and Peltier *** them,flexible tE devices have received more attention recently due to their better attachment to various heat sources and aimed components with arbitrary *** improve the performance of flexible tE devices for various application scenarios,large efforts have been made to design the leg patterns,the electrical and thermal contact issues,and the substrate and encapsulation materials for the decrease of heat *** paper is to review the advancements about the design of flexible inorganic tE devices over the last ***,the design of flexible thin-film tE devices based on the direction of temperature gradient,including the patterns of tE legs,the fabrication methods,and the flexible substrate materials is ***,the design of wearable tE devices that contains common architecture of the module,the substrates and encapsulations,the electrical and thermal contact,and some thin-film based wearable devices with curving tE legs is ***,the characterizations of the flexibility of tE devices and the current applications are ***,some views about the future development for tE devices are proposed.

关键词： flexible wearable thermoelectric device pattern contact

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A mechanism of defect-enhanced phase transformation kinetics in lithium iron phosphate olivine

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npj Computational Materials 2019年第1期5卷 102-110页

作者： Liang Hong Kaiqi yang Ming tang Department of Materials Science&NanoEngineering Rice UniversityHoustonTX 77005USA

Antisite defects are a type of point defect ubiquitously present in intercalation compounds for energy storage *** they are often considered a deleterious feature,here we elucidate a mechanism of antisite defects enhancing lithium intercalation kinetics in LiFePO_(4) by accelerating the FePO_(4)→LiFePO_(4) phase *** FeLi antisites block Li movement along the[010]migration channels in LiFePO_(4),phase-field modeling reveals that their ability to enhance Li diffusion in other directions significantly increases the active surface area for Li intercalation in the surface-reaction-limited kinetic regime,which results in order-of-magnitude improvement in the phase transformation rate compared to defect-free *** defects also promote a more uniform reaction flux on(010)surface and prevent the formation of current hotspots under galvanostatic(dis)charging *** analyze the scaling relation between the phase boundary speed,Li diffusivity and particle dimensions and derive the criteria for the co-optimization of defect content and particle geometry.A surprising prediction is that(100)-oriented LiFePO_(4) plates could potentially deliver better performance than(010)-oriented plates when the Li intercalation process is *** work suggests tailoring antisite defects as a general strategy to improve the rate performance of phase-changing battery compounds with strong diffusion anisotropy.

关键词： transformation defect kinetics

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A variational formula for controlled backward stochastic partial differential equations and some application

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Applied Mathematics(A Journal of Chinese Universities) 2014年第3期29卷 295-306页

作者： MENG Qing-xin tang Mao-ning Department of Mathematics Huzhou Teachers College School of Mathematical Sciences Fudan University

An optimal control problem for a controlled backward stochastic partial differential equation in the abstract evolution form with a Bolza type performance functional is considered. the control domain is not assumed to be convex, and all coefficients of the system are allowed to be random. A variational formula for the functional in a given control process direction is derived, by the Hamiltonian and associated adjoint system. As an application, a global stochastic maximum principle of Pontraygins type for the optimal controls is established.

关键词： Variational formula stochastic evolution equation backward stochastic evolution equation,stochastic maximum principle spike variation.

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广西田林高龙客家话的语音变异

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龙岩学院学报 2024年第4期42卷 43-50页

作者：唐七元刘玄杰广西大学广西南宁530004

田林县高龙客家话以方言岛的形式存在,其先民从广东梅县迁入已有近200年。与梅县客家话、五华客家话比较,高龙客家话保留了一部分源方言的语音特征,还产生了大量的语音变异现象,如出现新的声母和韵母[■][■][y],只有一套塞擦音声母[t■... 详细信息

田林县高龙客家话以方言岛的形式存在,其先民从广东梅县迁入已有近200年。与梅县客家话、五华客家话比较,高龙客家话保留了一部分源方言的语音特征,还产生了大量的语音变异现象,如出现新的声母和韵母[■][■][y],只有一套塞擦音声母[t■][t■^(h)],部分入声字舒化后读阳平等。这是高龙客家话与当地强势语言壮语、西南官话深度接触所导致的。

关键词：田林高龙客家话梅县客家话五华客家话语音变异

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