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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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Performance and bioparticle growth of anaerobic baffled reactor （ABR） fed with low-strength domestic sewage

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Frontiers of Environmental Science & Engineering 2015年第2期9卷 352-364页

作者： jing feng Yili wang Xueyuan JI Dongqin YUAN Hui LI College of Environmental Science and Engineering Beijing Key Laboratory for Source Control Technology of Water Pollution Beijing Forestry University Beijing 100083 China

We investigated the performance of a 15.3 L capacity anaerobic baffled reactor （ABR） toward the treatment of low-strength domestic wastewater. The start- up period of the ABR was finished within approximately 130 days at a temperature below 25~C. The average CODcr in the effluent was 165 mg.L 1 and the corresponding CODcr removal efficiency of the ABR was 52.3%. During the third stage （from day 130 to day 233） of ABR operation, the average CODcr in the effluent reached 71 mg· L^-1, which meets the secondary discharge requirement of the Integrated Wastewater Discharge Standard （GB 18918-2002, China）. Moreover, partial microbial separa- tion was observed along the five ABR compartments through scanning electron microscopic images. The geometric mean diameter of bioparticles in the five compartments increased from 0.050 mm to 0.111, 0.107, 0.104, 0.110, and 0.103 mm during the start-up stage. After operation for 179days, the further increased to 0.376, corresponding diameters 0.225, 0.253, 0.239, and 0.288mm, respectively. The fractal dimensions of the bioparticles indicated that these particles have smoother surfaces and more compact structures during ABR operation. Morphological analysis of the bioparticle sections demonstrated that the bioparticles have a pore volume of 30%-55%. The highest porosity was observed for the bioparticles in the second ABR compartment, whereas the lowest fractal dimension ofbioparticle section was observed in the fifth compartment.

关键词： anaerobic baffled reactor low-strengthdomestic wastewater start-up bioparticles morphology

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Covariate-Assisted Matrix Completion with Multiple Structural Breaks

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Journal of Systems Science & Complexity 2024年第2期37卷 692-728页

作者： MENG jing feng Long ZOU Changliang wang Zhaojun School of Statistics and Data Science KLMDASRLEBPSand LPMCNankai UniversityTianjin 300071China

In matrix completion,additional covariates often provide valuable information for completing the unobserved entries of a high-dimensional low-rank matrix *** this paper,the authors consider the matrix recovery problem when there are multiple structural breaks in the coefficient matrix β under the column-space-decomposition model A=Xβ+B.A cumulative sum(CUSUM)statistic is constructed based on the penalized estimation of β.Then the CUSUM is incorporated into the Wild Binary Segmentation(WBS)algorithm to consistently estimate the location of ***,a nearly-optimal recovery of A is *** findings are further corroborated via numerical experiments and a real-data application.

关键词： Additional covariates matrix completion multiple structural breaks wild Binary Segmentation

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Evaluating performance dependency of a geomorphologic instantaneous unit hydrograph-based hydrological model on DEM resolution

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Water Science and Engineering 2022年第3期15卷 179-188页

作者： Cheng Yao Zhi-jia Li Ke Zhang Ying-chun Huang jing-feng wang Satish Bastola College of Hydrology and Water Resources Hohai UniversityNanjing 210098China Yangtze Institute for Conservation and Development Hohai UniversityNanjing 210098China State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering Hohai UniversityNanjing 210098China China Meteorological Administration-Hohai University Joint Laboratory for Hydrometeorological Studies Hohai UniversityNanjing 210098China School of Civil and Environmental Engineering Georgia Institute of TechnologyAtlanta 30332USA Department of Civil and Environmental Engineering University of New OrleansNew Orleans 70148USA

The digital elevation model(DEM)is a type of model that has been widely used in terrain analysis and hydrological *** resolution influences the hydrological and geomorphologic features of delineated catchments and consequently affects hydrological *** study investigated the impacts of DEM resolution on the performance of the XAJ-GIUH hydrological model,a model coupling the widely used Xinanjiang(XAJ)hydrological model with the geomorphologic instantaneous unit hydrograph(GIUH),in flood simulations in small and medium-sized *** test the model performance,the model parameters were calibrated at a fine DEM resolution(30 m)and then directly transferred to the simulation runs using coarser ***,model recalibration was conducted at coarser DEM *** the simulation runs with the model parameters calibrated at the 30-m resolution,the DEM resolution slightly affected the overall shape of the simulated flood hydrographs but presented a greater impact on the simulated peak discharges in the two study *** XAJ-GIUH model consistently underestimated the peak discharges when the DEM resolution became *** qualified ratio of peak simulations decreased by 35%when the DEM resolution changed from 30 m to 600 ***,model recalibration produced comparable model per-formances when DEMs with different resolutions were *** study showed that the impact of DEM resolution on model performance can be mitigated by model recalibration to some extent,if the DEM resolution is not too coarse.

关键词： DEM resolution XAJ-GIUH model Flood simulation Model recalibration Small and medium-sized catchments

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Improved Visible-light Photocatalytic Properties of ZnFe2O4 Synthesized via Sol-gel Method Combined with a Microwave Treatment

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Chemical Research in Chinese Universities 2015年第3期31卷 439-442页

作者： feng jing wang Yuting ZOU Linyi LI Bowen HE Xiaofeng Lü Shengna CHEN Tingting Key Laboratory of Superlight Materials & Surface Technology Ministry of Education Harbin Engineering University Harbin 150001 P. R. China

ZnFe2O4（ZFO） was synthesized via a sol-gel method firstly, then the ZFO was irradiated with microwave treatment to obtain M-ZFO using NH4C1 as dispersant for 10 min to improve the photocatalytic activity. Large par- tides of ZFO were broken into small and uniform particles by the gases of hydrogen chlorine and ammonia during the decomposition of NH4Cl. Compared to ZnFe2O4 without microwave treatment（ZFO）, M-ZFO exhibits smaller particle size, higher surface area and larger saturation magnetization. More importantly, the photocatalytic activity of M-ZFO for methylene blue was increased by 25% compared with that of ZFO.

关键词： Photocatalyst Microwave treatment ZnFe2O4

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Extrusion 3D printing of carbon nanotube-assembled carbon aerogel nanocomposites with high electrical conductivity

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Nano Materials Science 2024年第3期6卷 312-319页

作者： Lukai wang jing Men Junzong feng Yonggang Jiang Liangjun Li Yijie Hu Jian feng Science and Technology on Advanced Ceramic Fibers and Composites Laboratory College of Aerospace Science and EngineeringNational University of Defense Technology109 De Ya RdChangshaHunan410073PR China

Carbon nanotubes(CNTs)with high aspect ratio and excellent electrical conduction offer huge functional improvements for current carbon ***,there remains a major challenge for achieving the on-demand shaping of carbon aerogels with tailored micro-nano structural textures and geometric ***,a facile extrusion 3D printing strategy has been proposed for fabricating CNT-assembled carbon(CNT/C)aerogel nanocomposites through the extrusion printing of pseudoplastic carbomer-based inks,in which the stable dispersion of CNT nanofibers has been achieved relying on the high viscosity of carbomer *** extrusion printing,the chemical solidification through polymerizing RF sols enables 3D-printed aerogel nanocomposites to display high shape fidelity in macroscopic *** from the micro-nano scale assembly of CNT nanofiber networks and carbon nanoparticle networks in composite phases,3D-printed CNT/C aerogels exhibit enhanced mechanical strength(fracture strength,0.79 MPa)and typical porous structure characteristics,including low density(0.220 g cm^(-3)),high surface area(298.4 m^(2)g^(-1)),and concentrated pore diameter distribution(~32.8nm).More importantly,CNT nanofibers provide an efficient electron transport pathway,imparting 3D-printed CNT/C aerogel composites with a high electrical conductivity of 1.49 S cm^(-1).Our work would offer feasible guidelines for the design and fabrication of shape-dominated functional materials by additive manufacturing.

关键词： Carbon aerogel Extrusion 3D printing Carbon nanotube Electrical conductivity Rheology

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An antistatic agent based on polyionic liquid applied to nylon 6

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Green Chemical Engineering 2024年第3期5卷 399-407页

作者： Shuangchan Fu Yinghao Yu feng wang jing Li Zhiqi Cai School of Chemistry and Chemical Engineering South China University of TechnologyGuangzhou510641China SCUT-Zhuhai Institute of Modern Industrial Innovation Zhuhai519175China Yantai Xintelu New Material Technology Co.LTD. Shandong264006China

In order to improve the electrical conductivity of nylon 6(PA6)and avoid misfires and explosions caused by static charge accumulation,a quaternary ammonium salt polyionic liquid(PIL)antistatic agent was synthesized in this *** surface resistance of PA6 was reduced to 10~8Ωwith the addition of 2 wt%antistatic agent,and the mechanical properties and aging resistance of the substrate were ***,the morphology and crystallinity of PIL/PA6 composites were further characterized by scanning electron microscope(SEM),energy dispersion spectrometer(EDS)and X-ray diffraction(XRD).It is worth noting that the quaternary ammonium salt polyionic liquid antistatic agent synthesized in this paper has the advantages of excellent antistatic effect,durability,low cost,and simple reaction condition,so it has a broad application prospect in the antistatic aspect of PA6.

关键词： Polyionic liquid Nylon 6 Antistatic agent

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Numerical Analysis of Perforation during Hydraulic Fracture Initiation Based on Continuous-Discontinuous Element Method

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Computer Modeling in Engineering & Sciences 2024年第8期140卷 2103-2129页

作者： Rui Zhang Lixiang wang jing Li Chun feng Yiming Zhang School of Civil and Transportation Engineering Hebei University of TechnologyTianjin300401China Key Laboratory for Mechanics in Fluid Solid Coupling Systems Institute of MechanicsChinese Academy of SciencesBeijing100190China School of Civil Engineering and Architecture Zhejiang Sci-Tech UniversityHangzhou310018China Jinyun Institute Zhejiang Sci-Tech UniversityLishui321400China

Perforation is a pivotal technique employed to establish main flow channels within the reservoir formation at the outset of hydraulic fracturing *** perforation designs is critical for augmenting the efficacy of hydraulic fracturing and boosting oil or gas *** this study,we employ a hybrid finite-discrete element method,known as the continuous–discontinuous element method(CDEM),to simulate the initiation of post-perforation hydraulic fractures and to derive enhanced design *** model incorporates the four most prevalent perforation geometries,as delineated in an engineering technical ***-world perforations deviate from the ideal cylindrical shape,exhibiting variable cross-sectional profiles that typically manifest as an initial constriction followed by an expansion,a feature consistent across all four perforation *** simulations take into account variations in perforation hole geometries,cross-sectional diameters,and perforation *** findings show that perforations generated by the 39g DP3 HMX perforating bullet yield the lowest breakdown pressure,which inversely correlates with increases in sectional diameter and perforation ***,this study reveals the relationship between breakdown pressure and fracture degree,providing valuable insights for engineers and designers to refine perforation strategies.

关键词： Hydraulic fracturing real perforation shape breakdown pressure perforation layout design CDEM

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Ds-echinoside A,a new triterpene glycoside derived from sea cucumber,exhibits antimetastatic activity via the inhibition of NF-κB-dependent MMP-9 and VEGF expressions

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Journal of Zhejiang University-Science B(Biomedicine & Biotechnology) 2011年第7期12卷 534-544页

作者： Qin ZHAO Zhi-dong LIU Yong XUE jing-feng wang Hui LI Qing-juan TANG Yu-ming wang Ping DONG Chang-hu XUE College of Food Science and Engineering Ocean University of China Qingdao 266003 China

Ds-echinoside A (DSEA),a non-sulfated triterpene glycoside,was isolated from the sea cucumber Pearsonothuria *** vitro and in vivo investigations were conducted on the effects of DSEA on tumor cell adhesion,migration,invasion,and *** this study,we found that DSEA inhibited the proliferation of human hepatocellular liver carcinoma cells Hep G2,with a half-maximal inhibitory concentration (IC50) of 2.65 μmol/L,and suppressed Hep G2 cell adhesion,migration,and invasion in a dose-dependent *** also reduced tube formation of human endothelial cells ECV-304 on matrigel in vitro and attenuated neovascularization in the chick embryo chorioallantoic membrane (CAM) assay in *** analysis revealed that DSEA significantly decreased the expression of matrix metalloproteinase-9 (MMP-9),which plays an important role in the degradation of basement membrane in tumor metastasis and *** also increased the protein expression level of tissue inhibitor of metalloproteinase-1 (TIMP-1),an important regulator of MMP-9 *** the results of Western blotting,the expressions of nuclear factor-kappa B (NF-κB) and vascular endothelial growth factor (VEGF) were found to be remarkably reduced by *** findings suggest that DSEA exhibits a significant antimetastatic activity through the specific inhibition of NF-κB-dependent MMP-9 and VEGF expressions.

关键词： Triterpene glycoside Ds-echinoside A (DSEA) Metastasis Angiogenesis Nuclear factor-κB (NF-κB) Matrix metalloproteinase-9 (MMP-9) Vascular endothelial growth factor (VEGF)

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Numerical simulation of melt flow and temperature field during DC casting 2024 aluminium alloy under different casting conditions

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China Foundry 2024年第4期21卷 387-396页

作者： Jin-chuan wang Yu-bo Zuo Qing-feng Zhu jing Li Rui wang Xu-dong Liu Key Laboratory of Electromagnetic Processing of Materials Ministry of EducationNortheastern UniversityShenyang 110819China School of Materials Science and Engineering Northeastern UniversityShenyang 110819China Engineering Research Center of Advanced Materials Preparing Technology Ministry of EducationShenyang 110819China CAS Key Laboratory of Nuclear Materials and Safety Assessment Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China

Casting speed,casting temperature and secondary cooling water flow rate are the main process parameters affecting the DC casting *** parameters significantly influence the flow and temperature fields during casting,which are crucial for the quality of the ingot and can determine the success or failure of the casting *** simulation,with the advantages of low cost,rapid execution,and visualized results,is an important method to study and optimize the DC casting *** the present work,a simulation model of DC casting 2024 aluminum alloy was established,and the reliability of the model was ***,the influence of casting parameters on flow field and temperature field was studied in detail by numerical simulation *** show that with the increase of casting speed,the melt flow becomes faster,the depths of slurry zone and mushy zone increase,and the variation of slurry zone depth is greater than that of mushy *** an increase in casting temperature,the melt flow rate increases,the depth of the slurry zone becomes shallower,and the depth of the mushy zone experiences only minor *** simulation results further indicate that the increase of the flow rate of the secondary cooling water slightly reduces the depths of both slurry and mushy zone.

关键词： aluminium DC casting flow field temperature field numerical simulation

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