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Rare Metals 2020年第2期39卷 147-155页

作者： Cong Yang Qing-Yan xu bai-Cheng Liu Key Laboratory for Advanced Materials Processing Technology(Ministry of Education) School of Materials Science and EngineeringTsinghua UniversityBeijing 100084China

The thermosolutal convection can alter segregation pattern,change dendrite morphology and even cause freckles formation in alloy *** this work,the multiphase-field model was coupled with lattice Boltzmann method to simulate the dendrite growth under melt convection in superalloy *** the isothermal solidification simulations,zero and normal gravitational accelerations were applied to investigate the effects of gravity on the dendrite morphology and the magnitude of melt *** solute distribution of each alloy component along with the dendrite tip velocity during solidification was obtained,and the natural convection has been confirmed to affect the microsegregation pattern and the dendrite growth *** the directional solidification simulations,two typical temperature gradients were applied,and the dendrite morphology and fluid velocity in the mushy zone during solidification were *** is found that the freckles will form when the average fluid velocity in the mushy zone exceeds the withdraw velocity.

关键词： Dendrite growth Natural convection Phasefield model Lattice Boltzmann method

Hot Corrosion Resistance of TB8 Titanium Alloy after ECAP and Heat Treatment

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Journal of Wuhan University of Technology(Materials Science) 2023年第6期38卷 1440-1448页

作者： LI Shuaidi xu Xiaojing bai Xiang CAO Bin Institute of Advanced Manufacturing and Modern Equipment Technology Jiangsu UniversityZhenjiang 212013China

The metastableβtitanium alloy TB8(Ti-12.76Mo-2.13Nb-2.73A1-0.16Si)was used as the original material,and the secondary processing method combining equal channel angular pressing(ECAP)and heat treatment was *** the help of optical microscope(OM),scanning electron microscope(SEM)and X-ray diffractometer(XRD),the corrosion behavior of TB8 titanium alloy after different secondary processing(800℃/850℃solid solution-520℃aging,ECAP-800℃/850℃solid solution-520℃aging,and800℃/850℃solid solution-ECAP-520℃aging)was *** experimental results show that the hot corrosion products of the six samples are similar,mainly Na_(2)Si_(2)O_(5),MoS_(2),TiCl_(2),Ti(SO_(4))_(2),and *** to the grains of the TB8 titanium alloy treated by 850℃solid solution-ECAP-520℃aging are obviously refined,the surface structure is the most smooth and dense,forming a continuous Al2O3protective film,and the surface defects are the least after *** corrosion layer thickness is the lowest(102.3μm),only 36.5%-81.4%of that of other secondary processing titanium *** addition,the corrosion kinetics curves of the six materials all follow parabolic laws,and the minimum corrosion weight gain of the samples after 850℃solutionECAP-520℃aging treatment is 0.7507 mg·mm^(-2),showing better hot corrosion resistance.

关键词： TB8 ECAP heat treatment hot corrosion resistance

Temperature influence on minimum fluidization velocity:Complexity,mechanism,and solutions

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Particuology 2024年第5期88卷 344-349页

作者： Qingjin Zhang Liangliang Fu Guangwen xu Dingrong bai Key Laboratory on Resources Chemicals and Material of Ministry of Education Shenyang University of Chemical TechnologyShenyang 110142China School of Materials Science and Engineering Shenyang University of TechnologyShenyang 110142China School of Chemical Engineering University of Science and Technology LiaoningAnshan 114051China

Fluidized-bed reactors are widely employed in various high-temperature industrial ***,it is crucial to understand the temperature effect on various fluidization phenomena,specifically the minimum fluidization velocity(U_(mf))that governs various aspects of fluidized bed *** this study,we comprehensively analyze U_(mf) data from the literature to unravel the complexity and underlying mechanisms of temperature influence on this critical *** research examines experimental data encompassing a wide range of temperatures,pressures,and solid *** analysis reveals that the influence of temperature on U_(mf) is fundamentally determined by the relative importance of hydrodynamic forces and interparticle forces within fluidized beds and is realized by three distinctive temperature-induced changes:gas properties,bed voidage,and physiochemical characteristics of *** this basis,an equation is derived to enable predictions of temperature influences on the minimum fluidization velocity under broad temperature conditions.

关键词： High-temperature gas-solids fluidized beds Minimum fluidization velocity Hydrodynamic forces Interparticle forces Bed voidage

Three-component one-pot synthesis of 1,2,3,4-tetrahydroquinoline derivatives in hexafluoroisopropanol

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Chinese Chemical letters 2008年第8期19卷 921-924页

作者： Jie Zhou bai Ling xu Institute of Materia Medica Chinese Academy of Medical Sciences ＆ Peking Union Medical College Beijing 100050 China

The one-pot aza-Diels-Alder reaction of substituted aromatic amines, ethyl glyoxylate and benzyl vinylcarbamate or N- benzyloxycarbonyl 2-pyrroline was conducted in hexafluoroisopropanol, providing the desired 1,2,3,4... 详细信息

关键词： Aza-Diels-Alder reaction Tetrahydroquinoline Hexafluoroisopropanol (HFIP) Fluorinated solvent

Grignard Addition to Quinoxalinium Salt: Synthesis of 1, 2-Dihydro-quinoxaline and 1, 2, 3, 4-Tetrahydroquinoxaline Derivatives

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Chinese Chemical letters 2006年第2期17卷 165-168页

作者： Lian You ZHENG xu bai The Center for Combinatorial Chemistry and Drug Discovery Jilin University Changchun 130012

Grignard additions to a quinoxalinium salt were studied. Depending on the ratio of the reagents and reaction temperature, 1, 2, 3, 4-tetrahydroquinoxaline and 1, 2-dihydroquinoxaline derivatives could be resulted sele... 详细信息

关键词： Grignard addition quinoxalinium salt dihydroquinoxaline tetrahydroquinoxaline.

Challenges and opportunities for engineering thermochemistry in carbon-neutralization technologies

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National Science Review 2023年第9期10卷 11-13页

作者： Guangwen xu Dingrong bai Chunming xu Mingyuan He Key Laboratory on Resources Chemicals and Materials Shenyang University of Chemical Technology College of Chemical Engineering and Environment China University of Petroleum-Beijing Shanghai Key Laboratory of Green Chemistry & Chemical Processes Department of Chemistry East China Normal University

Stalling and neutralizing carbon emissions while maintaining the quality of life is a global challenge of our ***>80% of the world’s energy and materials (***,cement,plastics)from fossil and carbonaceous resources,achieving this goal in a short time needs scientifically sound,economically sustainable and practically effective and deployable approaches,even though many strategies have been proposed by researchers and policymakers [1,2].

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Quasimonotone random and stochastic functional differential equations with applications

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Science China Mathematics 2023年第9期66卷 2021-2056页

作者： Xiaoming bai Jifa Jiang Tianyuan xu School of Mathematics Hefei University of TechnologyHefei 230009China Mathematics and Science College Shanghai Normal UniversityShanghai 200234China

In this paper, we study monotone properties of random and stochastic functional differential equations and their global dynamics. First, we show that random functional differential equations(RFDEs)generate the random dynamical system(RDS) if and only if all the solutions are globally defined, and establish the comparison theorem for RFDEs and the random Riesz representation theorem. These three results lead to the Borel measurability of coefficient functions in the Riesz representation of variational equations for quasimonotone RFDEs, which paves the way following the Smith line to establish eventual strong monotonicity for the RDS under cooperative and irreducible conditions. Then strong comparison principles, strong sublinearity theorems and the existence of random attractors for RFDEs are proved. Finally, criteria are presented for the existence of a unique random equilibrium and its global stability in the universe of all the tempered random closed sets of the positive cone. Applications to typical random or stochastic delay models in monotone dynamical systems,such as biochemical control circuits, cyclic gene models and Hopfield-type neural networks, are given.

关键词： quasimonotone random and stochastic functional differential equations eventual strong mono-tonicity strong comparison theorems strong sublinearity random attractor global convergence to random equilibrium

Conodont and Ammonoid Biostratigraphies around the Permian-Triassic Boundary from the Jianzishan of South China

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Journal of Earth Science 2017年第4期28卷 595-613页

作者： Ruoyu bai xu Dai Haijun Song State Key Laboratory of Biogeology and Environmental Geology School of Earth SciencesChina University of GeosciencesWuhan 430074China

Conodonts and ammonoids have played significant roles in the Permian-Triassic time- scale. In order to uncover the nature of the Permian-Triassic mass extinction and subsequent recovery, we studied conodont and ammonoid biostratigraphies around the Permian-Triassic boundary from Jianzishan of Hubei, South China. A total of four conodont zones and two ammonoid beds are recog- nized. In ascending order, the conodont zones are Late Changhsingian Clarkina changxingensis Zone, Clarkina yini Zone and Griesbachian Hindeodus parvus Zone, Hindeodus postparvus Zone; the ammon- oid beds are Late Griesbachian Ophiceras beds and Early Dienerian Ussuridiscus varaha beds. At Jian- zishan, Ophiceras beds are stratigraphically younger than Hindeodus parvus Zone, but it is likely to be the same level with Hindeoduspostparvus Zone. The Lower Dienerian in Bed 8 in this section is charac- terized by ammonoid Ussuridiscus varaha beds, which is associated with many Late Grieshachian cono- donts including Hindeodus postparvus, Hindeodus praeparvus, Hindeodus typicalis, Hindeodus pisai, Hindeodus latidentatus, Hindeodus parvus, Hindeodus anterodentatus and Isarcicella turgida, indicating these conodont species could pass through the Griesbachian-Dienerian boundary and occurred in the Early Dienerian oceans.

关键词： Permian-Triassic conodont ammonoid South China stratigraphy.

Control of floor heaves with steel pile in gob-side entry retaining

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International Journal of Mining Science and Technology 2016年第3期26卷 527-534页

作者： xu Ying Chen Jin bai Jianbiao School of Mines China University of Mining & Technology State Key Laboratory of Coal Resources and Mine Safety China University of Mining & Technology

A new approach named as steel pile method is innovatively proposed in this study to control severe floor heaves in gob-side entry retaining. It is required that the steel piles be installed in the floor corners with a certain interval before the influence of the dynamic pressure induced by current panel extraction. Using numerical simulation and theoretical analysis, this study investigated the interaction between the steel piles and the floor rocks during the service life of the steel piles, and revealed the mechanism of the steel piles in controlling floor heaves. The effect of the steel pile parameters on the control of floor heaves was presented and elaborated. It is found that the effectiveness of the steel piles in controlling floor heaves can be enhanced with greater installed dip angle, longer length and smaller interval of the steel *** with traditional methods, e.g., using floor anchor bolts and floor restoration, the advantages using steel pile were successfully defined in terms of controlling effect and economic benefits. It is hoped that the proposed method can contribute to the development of gob-side entry retaining technique.

关键词： Gob-side entry retaining Floor heave Steel pile Stress arch Control mechanism

Difference Equation for N-body Type Problem

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Communications in Mathematical Research 2009年第5期25卷 411-417页

作者： xu le-SHUN HAN YUE-CAI LIU bai-FENG College of Mathematics and Computer Science Nanjing Normal University Nanjing 210097 Department of Applied Mathematics Northwest A ＆ F University Yangling Shanxi 712100 School of Mathematics Jilin University Changchun 130012 Department of Mathematics and Information Science Shandong Institute

In this paper, the difference equation for N-body type problem is established, which can be used to find the generalized solutions by computing the critical points numerically. And its validity is testified by an exam... 详细信息

关键词： Difference equation N-bodytype problem critical point