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Effect of rare earth on primary carbides in H13 die steel and their addition method:a review

Journal of Iron and Steel Research International 2024年第3期31卷 531-551页

作者： Jing-feng Wang Lin-zhu Wang chao-yi chen Xiang Wang Fei Zhao School of Materials and Metallurgy Guizhou UniversityGuiyang 550025GuizhouChina Zhengzhou Railway Vocational and Technical College Zhengzhou 450000HenanChina Guizhou Provincial University Key Laboratory of High Performance Battery Materials Guizhou UniversityGuiyang 550025GuizhouChina Shougang Guiyang Special Steel Co. Guiyang 550005GuizhouChina

Larger-sized primary carbides lead to stress concentration during the application of H13 hot-work die steel,resulting in microcracks and fatigue *** earth was usually added to modify the carbides and *** existing literature is reviewed on the effect of rare earth on primary carbides in H13 steel.A comprehensive review on the effect of rare earth on the characteristics of primary carbides,i.e.,number,size,morphology,and thermal stability in H13 steel,was *** precipitation mechanism and nucleation of primary carbides with rare earth were *** position and form of rare earth in steel and their effects on alloying elements segregation were *** addition techniques of rare earth in H13 steel were compared,and the prospects for other uncommon rare earth and emerging technology were *** on the current references,it can be known that adding rare earth facilitated refined and dispersed primary *** size of primary carbides would be reduced,and their morphology would be improved because the rare earth inclusions formed in H13 steel can act as nucleation cores forγ-Fe orδ-Fe,refining the dendritic ***,the number of primary carbides at grain boundaries would be significantly ***,rare earth had little impact on thermal *** nucleation of primary carbides tended to be inhibited due to the modification of inclusions by rare earth which were likely to be nucleation cores for primary *** earth had been reported to affect the mechanism and process of primary carbide ***,the addition of rare earth can inhibit the segregation of alloying elements and carbon diffusion by ***,laboratory experiments and theoretical calcu-lations need to be conducted to study the states and evolution of rare earth steels.

关键词： Rare earth H13 die steel Primary carbide Nucleation Dendritic structure

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The Thickness of Some Complete Bipartite and Tripartite Graphs

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Acta Mathematicae Applicatae Sinica 2024年第4期40卷 1001-1014页

作者： Si-wei HU yi-chao chen Yali Peicui School Changsha 410021China School of Mathematics Suzhou University of Science and TechnologySuzhou 215009China

In this paper,we obtain the thickness for some complete k-partite graphs for k=2,*** first compute the thickness of K_(n,n+8)by giving a planar decomposition of K_(4k-1,4k+7)for k≥***,two planar decompositions for K_(1,g,g)(g-1)when g is even and for K^(1,g,1/2(g-1)2)when g is odd are *** a recursive construction,we also obtain the thickness for some complete tripartite *** results here support the long-standing conjecture that the thickness of K_(m,n)is[mn/2(m+n-2)]for any positive integers m,n.

关键词： thickness complete bipartite graph complete tripartite graph planar decomposition

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非极大部分对偶平面图的刻画与平面三角剖分图的部分对偶最大亏格

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数学学报（中文版） 2024年第3期67卷 531-538页

作者：秦楚陈仪朝苏州科技大学数学科学学院苏州215009

图嵌入G的部分对偶G^(A)是选择G的部分边集A做对偶,它是经典的庞加莱对偶G^(*)的推广.与经典的庞加莱对偶不同的是,部分对偶G^(A)的亏格往往不等于G的亏格.类似于黄-刘图的非上可嵌入性刻画定理,对平面图我们先证明了非极大部分对偶平... 详细信息

图嵌入G的部分对偶G^(A)是选择G的部分边集A做对偶,它是经典的庞加莱对偶G^(*)的推广.与经典的庞加莱对偶不同的是,部分对偶G^(A)的亏格往往不等于G的亏格.类似于黄-刘图的非上可嵌入性刻画定理,对平面图我们先证明了非极大部分对偶平面图结构定理,并由此确定了平面三角剖分图G的部分对偶最大亏格,即当G为3-圈时,G的部分对偶最大亏格为1;否则G的部分对偶最大亏格为其顶点数减1.

关键词：部分对偶极大部分对偶平面图平面三角剖分图部分对偶最大亏格

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Remarks on the Lower Bounds for the Average Genus

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Acta Mathematicae Applicatae Sinica 2011年第3期27卷 517-526页

作者： yi-chao chen College of mathematics and econometrics Hunan University 410082 Changsha China

Let G be a graph of maximum degree at most four. By using the overlap matrix method which is introduced by B. Mohar, we show that the average genus of G is not less than 1/3 of its maximum genus, and the bound is best... 详细信息

关键词： average genus lower bound girth overlap matrix

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The Total Embedding Distributions of Cacti and Necklaces

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Acta Mathematica Sinica,English Series 2006年第5期22卷 1583-1590页

作者： yi chao chen Yah Pei LIU Tao WANG College of Mathematics and Econometrics Hunan University Changsha 410082 P. R. China Department of Mathematics Beijing JiaoTong University Beijing 100044 P. R. China School of Computer and Information Technology Beijing Jiao Tong University Beijing 100044 P. R. China

Total embedding distributions have been known for only a few classes of graphs. In this paper the total embedding distributions of the cacti and the necklaces are obtained. Furthermore we obtain the total embedding di... 详细信息

关键词： overlap matrix total embedding distribution cacti necklaces

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Nonorientable Genera of Petersen Powers

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Acta Mathematica Sinica,English Series 2015年第4期31卷 557-564页

作者： Wen Zhong LIU Ting Ru SHEN yi chao chen Department of mathematics Nanjing University of Aeronautics and Astronautics College of Mathematics and Econometrics Hu'nan University

In the paper, we prove that for every integer n ≥ 1, there exists a Petersen power pn with nonorientable genus and Euler genus precisely n, which improves the upper bound of Mohar and Vodopivec＇s result [J. Graph Theory, 67, 1-8 （2011）] that for every integer k （2 ≤ k ≤ n- 1）, a Petersen power Pn exists with nonorientable genus and Euler genus precisely k.

关键词： Dot product Petersen power genus

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针刺治疗偏头痛的效应机制研究:来自脑影像研究的证据(Ⅰ)

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World Journal of Acupuncture-Moxibustion 2024年第1期34卷 16-23页

作者：刘国韵陈懿超曹子敏石安琪许璐凡李芷君杨泽秋闫超群王军北京中医药大学东直门医院针灸科北京100700

Objective:Magnetic resonance imaging(MRI)studies have demonstrated anatomical and functional alterations of brain regions in patients with migraine,and the efficacy of acupuncture for migraine could regulate these abnormal ***,its pathogenesis remains ambiguous,and inconsistent results have been *** purpose of this study was to explore abnormal structural and functional alterations in patients with migraine using voxel-based morphometry(VBM)analysis and a seed-based functional connectivity(FC)approach and to provide a basis for future ***:The study recruited 34 patients with migraine and 38 healthy controls who underwent structural and resting-state functional magnetic resonance imaging(fMRI).VBM was evaluated across the whole brain,and group differences in the gray matter(GM)were *** significantly altered GM volumes considered as the seeding area were further calculated for the FC of the whole *** correlation between structural or functional changes of the brain and clinical features was also ***:Patients with migraine manifested higher GM volumes in the left occipital lobe than healthy ***-based analyses demonstrated reduced FC between the left occipital lobe and right inferior frontal gyrus,extending to the anterior cingulate cortex(ACC)and right *** FC in the left ACC was positively correlated with visual analog scale(VAS)and self-rating anxiety scale(SAS).

关键词： Migraine Acupuncture Gray matter Voxel-based morphometry Functional connectivity Magnetic resonance imaging

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Optimization of iron and aluminum recovery in bauxite

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Journal of Iron and Steel Research International 2020年第3期27卷 310-318页

作者： Qian Long Jun-qi Li chao-yi chen Yuan-pei Lan Guo-ling Wei Department of Metallurgical Engineering College of Materials and MetallurgyGuizhou UniversityGuiyang 550025GuizhouChina Guizhou Province Key Laboratory of Metallurgical Engineering and Process Energy Saving Guiyang 550025GuizhouChina

Recovering iron and aluminum efficiently is the key route to utilize low-grade high-iron *** to optimize the iron separating process and elevate both Fe and Al recovery ratio,three different Fe-Al recovery processes with different magnetic roasting(R),Bayer leaching process(L)and magnetic separation(S)orders were *** studied processes include bauxite leaching→red mud roasting→magnetic separation(L-R-S),bauxite roasting→magnetic separation→leaching(R-S-L)and bauxite roasting→leaching→magnetic separation(R-L-S).The iron recovery ratio,Fe2O3 content in iron concentration and the bauxite dissolution ratio of each process were ***,the optimizations of the leaching,roasting and magnetic separation conditions were *** indicate that the R-S-L process should be an advisable order to recover both alumina and *** the three processes,the R-S-L route had the highest alumina dissolution ratio and iron recovery ratio,which was 86.20%and 69.58%,respectively,while the Fe2O3 content of the iron concentrate was 40.66%.

关键词： High-iron bauxite Magnetic roasting Magnetic separation Recovery ratio Dissolution ratio

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Suspension calcination and alkali leaching of low-grade high-sulfur bauxite:Desulfurization, mineralogical evolution and desilication

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International Journal of Minerals,Metallurgy and Materials 2020年第5期27卷 602-610页

作者： Hong-fei Wu Jun-qi Li chao-yi chen Fei-long Xia Zhen-shan Xie Department of Metallurgical Engineering College of Materials and MetallurgyGuizhou UniversityGuiyang 550025China Guizhou Province Key Laboratory of Metallurgical Engineering and Process Energy Saving Guiyang 550025China

To enable the utilization of low-grade and high-sulfur bauxite, the suspension calcination was used to remove the sulfur and the activate silica minerals, and the calcinated bauxite was subjected to a desilication process in Na OH solution under atmospheric pressure. The desulfurization and desilication properties and mineralogical evolution were studied by X-ray diffraction, thermogravimetry–differential thermal analysis, scanning electron microscopy, and FactSage methods. The results demonstrate that the suspension calcination method is efficient for sulfur removal: 84.21% of S was removed after calcination at 1000°C for 2 min. During the calcination process, diaspore and pyrite were transferred to α-Al2O3, magnetite, and hematite. The phase transformation of pyrite follows the order FeS2 → Fe3O4 → Fe2O3, and the iron oxides and silica were converted into iron silicate. In the alkali-soluble desilication process, the optimum condition was an alkali solution concentration of 110 g/L, a reaction time of 20 min, and a reaction temperature of 95°C. The corresponding desilication ratio and alumina loss ratio were 44.9% and 2.4%, respectively, and the alumina-to-silica mass ratio of the concentrate was 7.9. The Al2O3·2SiO2, SiO2, and Al2O3 formed during the calcination process could react with Na OH solution, and their activity decreased in the order of Al2O3·2 SiO2, SiO2, and Al2O3.

关键词： low-grade bauxite sulfur suspension calcination alkali-soluble desilication Bayer process

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Agglomeration behavior of alumina inclusions and calcium aluminate inclusions on molten nickel-based superalloy surface

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Journal of Iron and Steel Research International 2023年第11期30卷 2318-2327页

作者： Rui-zhi Gao Lin-zhu Wang chao-yi chen Shu-feng Yang Xiang Li yin Zhang School of Materials and Metallurgy Guizhou UniversityGuiyang550025GuizhouChina School of Metallurgical and Ecological Engineering University of Science and Technology BeijingBeijing100083China Department of Materials and Metallurgy Engineering Guizhou Institute of TechnologyGuiyang550003GuizhouChina

Understanding the interactive forces of inclusions on the surface of molten nickel-based superalloys and finding methods to disperse these inclusions help improve performance and service *** aggregation behavior of aluminum oxide(Al_(2)O_(3))and calcium aluminate inclusions with different sizes and spacings on the surface of molten nickel-based superalloys was observed in-situ using a high-temperature confocal laser scan *** attractive force acted on Al2O3 inclusions with radii of 3.5-6μm was found ranging from 6.2×10-18 to 3.6×10-15 N,and that of CaO·2Al2O3(CA2)inclusions with radii of 3-5.5μm ranging from 3.5×10-19 to 8.3×10-15 *** capillary force acted on inclusions on the surface of nickel-based superalloy was calculated based on the Kralchevsky-Paunov model and investigated as a function of inclusion size,spacing,and *** calculated results were in the same trend as the experimental *** capillary force acted on inclusions was also affected by their contact angle,the density,surface energy,and oxygen content of the molten *** decreased with increasing alloy density and decreasing contact angle between inclusion with ***,the attractive force acted on Al2O3 inclusions was smaller on the surface of molten nickel-based superalloy than that of molten *** the oxygen content in the molten nickel-based alloy could increase its surface energy,and the attractive force acted on the inclusions would *** the oxygen content in the molten nickel-based alloy decreased from 0.05 to 0.0001 wt.%,the capillary force acted on the Al2O3 inclusions decreased from 1.7×10-18 to 3.6×10-19 N,reduced by 79%(1.4×10-18 N).

关键词： Inclusion Nickel-based superalloy Capillary force Alumina Calcium aluminate

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