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Effect of droplet characteristics on liquid-phase distribution in spray zone of internal mixing air-mist nozzle

China Foundry 2024年第2期21卷 185-196页

作者： wei-li wu Chang-gui Cheng Yang li Shi-fa wei De-li Chen The State Key Laboratory of Refractories and Metallurgy Wuhan University of Science and TechnologyWuhan 430081China Hubei Provincial Key Laboratory for New Processes of Ironmaking and Steelmaking Wuhan University of Science and TechnologyWuhan 430081China Technology Center Fushun Special Steel Co.Ltd.Fushun 113001LiaoningChina

In continuous casting production,droplet characteristics are important parameters for evaluating the nozzle atomization quality,and have a significant impact on the secondary cooling effect and the slab *** order to study the behavior of atomized droplets after reaching the slab surface and to optimize the spray cooling effect,the influence of droplet diameter and droplet velocity on the migration behavior of droplets in the secondary cooling zone was analyzed by FLUENT *** show that the droplets in the spray zone and on the slab surface are mainly concentrated in the center,thus,the liquid volume fraction in the center is higher than that of either *** the droplet diameter increases,the region of high liquid volume fraction on the slab surface becomes wider,and the liquid phase distribution in the slab width direction becomes *** increasing the droplet velocity at the nozzle exit has little effect on droplet diffusion in the spray zone,the distribution becomes more uneven due to more liquid reaches the slab surface per unit time.A prediction formula of the maximum water flow rate on the slab surface for specific droplet characteristics was proposed based on dimensionless analysis and validated by simulated data.A nozzle spacing of 210 mm was recommended under the working conditions in this study,which ensures effective coverage of the spray water over the slab surface and enhances the distribution uniformity of water flow rate in the transverse direction.

关键词： continuous casting secondary cooling zone internal mixing air-mist nozzle droplet characteristics liquid phase distribution water flow rate

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Effects of argon blowing at tundish upper nozzle on multiphase flow behavior in nozzle

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Journal of Iron and Steel Research International 2022年第4期29卷 588-600页

作者： Xu-feng Qin Chang-gui Cheng Yang li wei-li wu Yan Jin The State Key Laboratory of Refractories and Metallurgy Wuhan University of Science and TechnologyWuhan 430081HubeiChina Hubei Provincial Key Laboratory for New Processes of Ironmaking and Steelmaking Wuhan University of Science and TechnologyWuhan 430081HubeiChina

In continuous casting,the argon blowing at the tundish upper nozzle is usually used to prevent nozzle clogging,whose effect is closely related to the migration of argon bubbles and the flow behavior of the liquid steel in the ***,to investigate the effects of argon blowing at the tundish upper nozzle on multiphase flow behavior in nozzle,a threedimensional model of the tundish–nozzle–mold was established for numerical *** results indicate that the argon bubbles injected from the inner wall of the tundish upper nozzle first move downward along the nozzle wall under the action of the liquid *** the distance from the tundish upper nozzle increases,the argon bubbles gradually diffuse to the center of the *** with no argon blowing,the liquid steel velocity increases in the center of the nozzle and decreases near the wall with argon *** increasing the argon flow rate,the concentration of bubbles in the nozzle increases,and the process of bubble group diffusion to the center region of the nozzle speeds *** in turn increases the liquid steel velocity at the center of the nozzle but reduces near the *** increasing the casting speed,the concentration of bubbles in the nozzle decreases,the length of the bubble group near the nozzle wall is extended,and the liquid steel velocity at the center region and near-wall region of the nozzle *** mechanism of argon blowing at the tundish upper nozzle to prevent nozzle clogging is mainly realized by the isolation effect of the argon bubble group on the inner wall of the nozzle.

关键词： Argon blowing Tundish upper nozzle Nozzle clogging Numerical simulation

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Set Function Optimization

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Journal of the Operations Research Society of China 2019年第2期7卷 183-193页

作者： wei-li wu Zhao Zhang Ding-Zhu Du Department of Computer Science University of Texas at DallasRichardsonTX 75080USA Department of Computer Science Zhejiang Normal UniversityJinhua 321004ZhejiangChina

This article is an introduction to recent development of optimization theory on set functions,the nonsubmodular optimization,which contains two interesting results,DS(difference of submodular)functions decomposition and sandwich theorem,together with iterated sandwich method and data-dependent *** potential research problems will be mentioned.

关键词： Set function Optimization DS decomposition・Sandwich theorem Iterated sandwich method

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One-pot Synthesis of 1,5-Diaza-2,6-cyclooctadiene-3,7-dicarboxylates Through a Multiple-component Reaction

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Chemical Research in Chinese Universities 2014年第3期30卷 387-389页

作者： li Yufeng WANG Xinglong li wei wu Zhengguang SHI Jie MA Hongfei College of Science Nanjing Tech University Nanjing 211816 P. R. China

Methyl propiolate, formaldehyde, and various acyclic amines were assembled in one-pot into a series of 1,5-diaza-2,6-cyclooctadiene-3,7-dicarboxylates in moderate to good yields. This multiple-component reaction benef... 详细信息

关键词： Multiple-component reaction Methyl propiolate 1,5-Diaza-2,6-cyclooctadiene-3,7-dicarboxylate

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Preparation and Characterization of Microcapsules for Self-healing Materials

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Chemical Research in Chinese Universities 2010年第3期26卷 496-500页

作者： liAO Le-ping ZHANG wei ZHAO Yang li wu-Jun National Key Laboratory for Remanufacturing Academy of Armored Force Engineering Beijing 100072 P. R. China

The urea-formaldehyde（UF） capsules filled with a healing agent, a mixture of epoxy resins（epoxy 711 and E-51） as core material, were produced by means of one step in-situ polymerization. The characteristics of these microcapsules were studied via scanning electron microscopy（SEM）, particle size analysis, FTIR and DSC/TGA. The results show that the dispersed and integrated microcapsules of 5 μm in shell thickness were synthesized successfully. The capsules were produced with diameters ranging from 10 to 250 μm via controlling agitation rate. Young＇s modulus of the capsule was a little lower than those of the epoxy resins, but the microcapsules having such a shell thickness were robust enough to survive handling during manufacturing self-healing composites. When damage occurred in the epoxy matrix, the crack could rupture the microcapsule to make the repairing agent release.

关键词： Urea-formaldehyde Microcapsule Epoxy resin Self-healing

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Shared p-cycles design for dual link failure restorability in optical WDM networks

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The Journal of China Universities of Posts and Telecommunications 2007年第3期14卷 74-78页

作者： XIE Zheng-cheng XING Jun-wei wu li JI Yue-feng Key Laboratory of Optical Communications and lightwave Technologies Beijing University of Posts and Telecommunications Beijing 100876 China

Pre-configured cycles （p-cycles） can attain high capacity efficiency and fast protection switching times in wavelength division multiplexing （WDM） networks. This article proposes the weighted straddling link algorithm（WSLA） for generating a subset of all cycles that can guarantee 100% restorability in case of dual link failure, and give an integer linear programming（1LP） formulation that solves the shared p-cycles design problem minimizing the total spare capacities. Numerical result shows that our method can achieve 100% dual link failure restorability with acceptable spare capacity. The larger standard deviation of demand set and the larger node degree network, the better the shared p-cycles scheme performs.

关键词： dual link failure p-cycles WDM

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Numerical simulation on gas–liquid multiphase flow behavior under coupling effects of annular gas curtain and swirling flow at tundish upper nozzle

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Journal of Iron and Steel Research International 2024年第11期31卷 2693-2709页

作者： Xu-feng Qin Chang-gui Cheng Yang li wei-li wu Hao Chen Chao-fa Zhao Yan Jin The State Key Laboratory of Refractories and Metallurgy Wuhan University of Science and TechnologyWuhan430081HubeiChina Hubei Provincial Key Laboratory for New Processes of Ironmaking and Steelmaking Wuhan University of Science and TechnologyWuhan430081HubeiChina

A three-dimensional mathematical model has been established for a novel metallurgy process coupling an annular gas curtain with swirling flow at tundish upper nozzle. The discrete phase model and volume of fluid model were applied to simulate the gas–liquid multiphase flow behavior in tundish and nozzle. The effect of argon flow rate on the migration behavior of bubbles and interface behavior between steel and slag was also investigated. The presented results indicate that the novel coupling process can significantly change the flow pattern in the stream zone of a tundish, prolong the average residence time of liquid steel, and reduce the dead fraction. A complete annular gas curtain is formed around the stopper rod of tundish. Under the action of drag force of liquid steel, a part of small bubbles enter the nozzle through the swirling grooves and gather toward the center of the nozzle by centripetal force. As the argon flow rate increases, the volume fraction of argon gas entering the nozzle increases, which enhances the swirl intensity and increases the concentration of bubbles in the nozzle. To avoid the formation of slag open eye in tundish, the argon flow rate should not exceed 8 L min−1.

关键词： Annular gas curtain Swirling flow Tundish upper nozzle Multiphase flow Numerical simulation

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Luminescent Nanocrystalline Silicon Carbide Thin Film Deposited by Helicon Wave Plasma Enhanced Chemical Vapour Deposition

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Chinese Journal of Aeronautics 2006年第B12期19卷 96-101页

作者： LU Wan-bing YU wei wu li-ping CUI Shuang-kui FU Guang-sheng College of Physics Science and Technology Hebei University Baoding 071002 China

Hydrogenated nanocrystalline silicon carbide （SIC） thin films were deposited on the single-crystal silicon substrate using the helicon wave plasma enhanced chemical vapor deposition （HW-PECVD） technique. The influences of magnetic field and hydrogen dilution ratio on the structures of SiC thin film were investigated with the atomic force microscopy （AFM）, the Fourier transform infrared absorption （FTIR） and the transmission electron microscopy （TEM）. The results indicate that the high plasma activity of the helicon wave mode proves to be a key factor to grow crystalline SiC thin films at a relative low substrate temperature. Also, the decrease in the grain sizes from the level of microcrystalline to that of nanocrystalline can be achieved by increasing the hydrogen dilution ratios. Transmission electron microscopy measurements reveal that the size of most nanocrystals in the film deposited under the higher hydrogen dilution ratios is smaller than the doubled Bohr radius of 3C-SiC （approximately 5.4 nm）, and the light emission measurements also show a strong blue photoluminescence at the room temperature, which is considered to be caused by the quantum confinement effect of small-sized SiC nanocrystals.

关键词： silicon carbide nanostructures plasma processing deposition

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New Hydrogen Bonded Supramolecular Hydrogels Formed through Gelating Two Isomeric Building Units Simultaneously

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Chinese Chemical Letters 2006年第10期17卷 1388-1390页

作者： Ji wei wu li Ming TANG Kai CHEN liang YAN Yu Jiang WANG Laboratory of Advanced Materials Department of Chemical Engineering Tsinghua University Beijing 100084

New hydrogen bonded supramolecular hydrogels were formed through simultaneously gelating two isomeric building units, 4-oxo-4-（2-pyridinylamino）butanoic acid （G1） and 4-oxo-4-（3-pyridinylamino）butanoic acid （G2... 详细信息

关键词： Supramolecular hydrogel hydrogen bond gelation.

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Endoplasmic reticulum stress-induced apoptosis in the penumbra aggravates secondary damage in rats with traumatic brain injury

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Neural Regeneration Research 2016年第8期11卷 1260-1266页

作者： Guo-zhu Sun Fen-fei Gao Zong-mao Zhao Hai Sun wei Xu li-wei wu Yong-chang He Department of Neurosurgery Second Hospital of Hebei Medical UniversityShijiazhuangHebei ProvinceChina Department of Pharmacology Shantou University Medical CollegeShantouGuangdong ProvinceChina Division of Neurological Surgery Barrow Neurological InstituteSt Joseph's Hospital and Medical CenterPhoenixAZUSA

Neuronal apoptosis is mediated by intrinsic and extrinsic signaling pathways such as the membrane-mediated,mitochondrial,and endoplasmic reticulum stress *** studies have examined the endoplasmic reticulum-mediated apoptosis pathway in the penumbra after traumatic brain injury,and it remains unclear whether endoplasmic reticulum stress can activate the caspase-12-dependent apoptotic pathway in the traumatic ***,we established rat models of fluid percussion-induced traumatic brain injury and found that protein expression of caspase-12,caspase-3 and the endoplasmic reticulum stress marker 78 k Da glucose-regulated protein increased in the traumatic penumbra 6 hours after injury and peaked at 24 ***,numbers of terminal deoxynucleotidyl transferase-mediated d UTP nick end labeling-positive cells in the traumatic penumbra also reached peak levels 24 hours after *** findings suggest that caspase-12-mediated endoplasmic reticulum-related apoptosis is activated in the traumatic penumbra,and may play an important role in the pathophysiology of secondary brain injury.

关键词： nerve regeneration endoplasmic reticulum stress apoptosis caspase-12 caspase-3 traumatic penumbra traumatic brain injury neural regeneration

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