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Case-Based Reasoning(CBR) Model for Ultra-Fast Cooling in Plate Mill

Chinese Journal of Mechanical Engineering 2014年第6期27卷 1264-1271页

作者： HU Xiao wang Zhaodong wang guodong State Key Laboratory of Rolling and Automation Northeastern University

New generation thermo-mechanical control process（TMCP） based on ultra-fast cooling is being widely adopted in plate mill to product high-performance steel material at low cost. Ultra-fast cooling system is complex because of optimizing the temperature control error generated by heat transfer mathematical model and process parameters. In order to simplify the system and improve the temperature control precision in ultra-fast cooling process, several existing models of case-based reasoning（CBR） model are reviewed. Combining with ultra-fast cooling process, a developed R5 CBR model is proposed, which mainly improves the case representation, similarity relation and retrieval module. Certainty factor is defined in semantics memory unit of plate case which provides not only internal data reliability but also product performance reliability. Similarity relation is improved by defined power index similarity membership function. Retrieval process is simplified and retrieval efficiency is improved apparently by windmill retrieval algorithm. The proposed CBR model is used for predicting the case of cooling strategy and its capability is superior to traditional process model. In order to perform comprehensive investigations on ultra-fast cooling process, different steel plates are considered for the experiment. The validation experiment and industrial production of proposed CBR model are carried out, which demonstrated that finish cooling temperature（FCT） error is controlled within±25℃ and quality rate of product is more than 97%. The proposed CBR model can simplify ultra-fast cooling system and give quality performance for steel product.

关键词： ultra-fast cooling plate mill case-based reasoning case representation similarity relation retrieval module

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Analytical Solution for Three-dimensional Forging Taking into Account Bulging of Sides by Mean Yield Criterion

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Chinese Journal of Mechanical Engineering 2010年第4期23卷 477-483页

作者： DU Haijun ZHAO Dewen wang Genji wang guodong State Key Laboratory of Rolling and Automation Northeastern University Shenyang 110004 China

Currently, for some complex plastic deformations, the analytical solution can not be obtained by using Mises yield criterion, because Mises yield criterion is nine dimensions, the velocity field is complex, and the solving methods are not innovative. Corresponding solutions of these problems are that yield criterion is linearized to reduce the variable numbers, and the velocity field and the solving methods are reasonably simplified, respectively. In this paper, a new linear yield criterion--mean yield（MY） criterion and inner-product of strain rate vector are used to analytically solve 3D forging taking into account bugling of sides. The velocity field is expressed as a vector in three dimensions, and rotation and divergence are applied to confirm that the velocity field is kinematically admissible. Then, the corresponding strain rate tensor of the velocity field is transformed into principal one by making the determinant of coefficients of the tensor cubic equation be zero. By using MY criterion, the plastic power is term by term integrated and summed according to inner-product of strain rate vector. An upper bound analytical solution is obtained for the forging, and verified by a pure lead press test. The test result turns out that the total pressure calculated by MY criterion is higher by 2.5%-15% than measuring value. In addition, a measuring formula of bulging parameter （a） is proposed, but the values of a measured by the formula are lower than those optimized by the golden section search. The total pressure calculated by MY criterion is compared with the ones by twin shear, Trasca yield, and Mises yield criterion. The comparing result shows that the total pressure calculated by MY criterion is slightly higher than the mean value of that by twin shear and Trasca yield criterion, and lower than that by Mises yield criterion, but more close to that by Mises yield criterion compared with that by other two. The proposed analytical solving methods can be effectively

关键词： mean yield criterion three-dimensional forging bulging strain rate vector inner-product

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Numerical Modeling of Growth Kinetics of Pro-eutectoid Ferrite Transformed from Austenite in Fe-C-∑X Alloys

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Journal of Materials Science & Technology 2005年第6期21卷 795-798页

作者： Zhenyu LIU guodong wang Toshio Narita State Key Lab for Rolling Technology and Automation Northeastern University Shenyang 110004 China Lab for Interface Control Engineering Hokkaido University Sapporo Japan

In the present paper, a numerical modeling was developed to simulate the growth kinetics of ferrite transformed from austenite in Fe-C-∑X （X denotes substitution elements, such as Mn, Ni, Cr etc.） steels by solving the diffusion equation using finite difference method （FDM）. Coupled with the kinetic modeling, thermodynamic calculations were carried out to determine the γ/α phase equilibrium conditions using a para-equilibrium （PE） model. The dissipation of free energy for γ→α phase transformation due to the so-called solute drag effect （SDE） was taken into account in the thermodynamic modeling. With this modeling, simulations on the growth kinetics of ferrite in the steels containing austenite-stabilizing and ferrite-stabilizing elements （such as Ni, Mn and Si, Cr, respectively） were performed, which indicates that it deviates from the parabolic growth rate law after the initial stage of transformation. The results were compared with the experimental values given by Bradley and Aaronson, showing that this model has a reasonably good accuracy to predict the growth kinetics of ferrite.

关键词： Numerical modeling Fe-C-∑X steels γ→α phase transformation Para-equilibrium model

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Steady vortex patches near a nontrivial irrotational flow

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Science China Mathematics 2021年第5期64卷 947-962页

作者： Daomin Cao guodong wang Weicheng Zhan Institute of Applied Mathematics Academy of Mathematics and Systems ScienceChinese Academy of SciencesBeijing 100190China School of Mathematical Sciences University of Chinese Academy of SciencesBeijing 100049China

In this paper, we study the vortex patch problem in an ideal fluid in a planar bounded domain. By solving a certain minimization problem and studying the limiting behavior of the minimizer, we prove that for any harmonic function q corresponding to a nontrivial irrotational flow, there exists a family of steady vortex patches approaching the set of extreme points of q on the boundary of the domain. Furthermore, we show that each finite collection of strict extreme points of q corresponds to a family of steady multiple vortex patches approaching it.

关键词： Euler equation incompressible fluids vortex patch variational problem irrotational flow

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Simulated Calculations of Strain Induced Precipitation Behaviorin a Nb-Ti-V Steel

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Journal of Materials Science & Technology 1998年第6期14卷 571-573页

作者： Qu, Jinbo wang, Zhaodong Liu, Xianghua wang, guodong NE Univ Technol State Key Lab Rolling & Automat Shenyang 110006 Peoples R China

On the basis of regular solution sublattice model and classical nucleation and growth theory, strain induced precipitation kinetics in Nb-Ti-V combined treated microalloying steels has been calculated. The calculated precipitation-time-temperature diagram is in reasonable agreement with experimental results obtained from isothermal stress relaxation method. (Edited author abstract) 11 Refs.

关键词： Steel

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Analysis of Propagation Characteristics of Electromagnetic Disturbance from the Off-Line of Pantograph-Catenary in High-Speed Railway Viaducts

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Chinese Journal of Electronics 2020年第5期29卷 966-972页

作者： LI Meng WEN Yinghong SUN Xiaokang wang guodong School of Electronic and Information Engineering Beijing Jiaotong University Beijing Engineering Research Center of EMC and GNSS Technology for Rail Transportation Hangzhou Hikvision Digital Technology Co. Ltd.

Pantograph arcing caused by Off-line of pantograph-catenary(OLPC) will generate Electromagnetic disturbance(EMD), which will affect train control system and communication system. This paper proposes a simplified model of the train and pantograph to investigate propagation characteristics of EMD from OLPC in the viaduct scenario, containing attenuation law in transverse and longitudinal directions. As a result, the electric field strength of EMD from OLPC increases with distance in transverse direction from 10 m to 30 m in the viaduct scenario, which is different from the ground scenario. Thefitting formulas are found to research the attenuation law at different frequency points. We get the conclusion that the limit and measurement distance is not applicable for the viaduct scenario in current standard. To prove this,measurement in the viaduct scenario is completed, and the plausible evidence to explain the result is *** results are useful in the measurement of radiated emissions, on-board equipment layout and the research of standard in high-speed railway.

关键词： Electromagnetic disturbance (EMD) Off-line of pantograph-catenary (OLPC) Propagation Measurement Viaduct

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Microstructure and toughness of thick-gauge pipeline steel joint via double-sided friction stir welding combined with preheating

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International Journal of Minerals,Metallurgy and Materials 2023年第4期30卷 724-733页

作者： Guangming Xie Ruihai Duan Yuqian wang Zong’an Luo guodong wang State Key Laboratory of Rolling and Automation Northeastern UniversityShenyang 110819China

Fusion welding easily causes microstructural coarsening in the heat-affected zone(HAZ) of a thick-gauge pipeline steel joint. This is most significant in the inter-critically coarse-grained HAZ(ICCGHAZ), which considerably deteriorates the toughness of the joint. In the present work, 11-mm thick pipeline steel was joined by preheating and double-sided friction stir welding(FSW). A comparative study on the microstructure and toughness in the ICCGHAZs for FSW and gas metal arc welding(GMAW) was performed. The toughness in the ICCGHAZ for FSW was improved significantly than that in the ICCGHAZ for GMAW. Generally, the nugget zone(NZ) has a coarse microstructure in the FSW steel joint formed at the highest peak temperature. However, in the current study, the microstructure in the one-pass NZ was remarkably refined owing to the static recrystallization of ferrite. An excellent toughness was achieved in the NZ of the pipeline steel joint that employed FSW.

关键词： pipeline steel thick-gauge plate friction stir welding microstructure toughness

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Effect of Nanoparticle Type and Surfactant on Heat Transfer Enhancement in Spray Cooling

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Journal of Thermal Science 2020年第3期29卷 708-717页

作者： wang Bingxing LIU Zhixue ZHANG Bo XIA Yue wang Zhaodong wang guodong The state key laboratory of rolling and automation(RAL) Northeastern UniversityShenyang 110819China

In this study,the heat transfer characteristics of nanofluids used in spray cooling systems were *** nanofluids,i.e.,Cu,CuO,and Al2 O3,respectively,with volume fractions ranging from 0.1%to0.5%,as well as different volume fractions of a surfactant Tween 20,were *** addition,their contact angles were measured to examine the heat-transfer *** the same experimental conditions,with the increase in the volume fraction of the Cu nanoparticles from 0.1%to 0.5%,the maximum heat flux qmax increased from 3.36 MW/m2 to 3.48 MW/m2 from the impinging central point to r=30 mm(r is the distance from the impingement point),and the corresponding temperature of qmax increased from 400℃to 420℃.Results revealed that with increasing Tween 20 concentrations,the contact angle decreased because of the decrease in the surface tension of nanofluids and improvement of the wetting ability,and the corresponding qmax increased from 3.48 MW/m2 to 3.94 MW/m2 at the impact central point.

关键词： spray cooling nanofluids surfactant wettability heat flux

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Influence of the finish rolling temperatures on the microstructure and texture evolution in the ferritic stainless steels

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Acta Metallurgica Sinica(English Letters) 2011年第5期24卷 343-350页

作者： Fei GAO Zhenyu LIU Haitao LIU guodong wang The State Key Laboratory of Rolling and Automation Northeastern University Shenyang 110819 China

The influence of the finish rolling temperature on the microstructure and texture evolution of Nb and B micro-alloyed ultra purified Cr17 ferritic stainless steels was investigated. The hot rolled bands were produced by conventional rolling process and the finish rolling at relatively low temperatures or ＂warm rolling＂. The microstructure was observed by optical microscopy, scanning electron microscopy and transmission electron microscopy, and X-ray diffraction was used to characterize the texture evolution processes. The results showed that as compared to conventional hot rolling process, the warm rolling has led to the refined and homogeneous microstructure and uniform recrystallization texture along γ-fiber in final sheets, indicating that the finish rolling at relatively low temperatures can be the effective way to improve significantly the formability of final sheets.

关键词： Ultra purified Cr17 ferritic stainless steel Finish rolling temperature Microstructure Texture

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Gauge-meter model building based on the effect of elastic deformation of rolls in a plate mill

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Journal of University of Science and Technology Beijing 2007年第4期14卷 381-386页

作者： Xianlei Hu Zhaodong wang Zhong Zhao Xianghua Liu guodong wang State Key Laboratory of Rolling Technology and Automation of Tandem Rolling Northeastern University Shenyang 110004 China

The calculation error of the gauge-meter model will affect the gap setting precision and the self-learn precision of rolling force. The precision of the gauge-meter model is strongly influenced by plate width, working roll radius, backup roll radius, working roll crown, backup roll crown, and rolling force. The influence rules are hard to get by measuring. Taking a conventional 4-h plate mill as the research subject, these influences were transferred into the calculation of roll deflection and flattening deformation. To calculate these deformations, the theory of the influence function method was adopted. By modifying the traditional gauge-meter model, a novel model of the effect of roll elastic deformation on the gap setting was built by data fitting. By this model, it was convenient to analyze the variation caused by the rolling condition. Combining the elastic deformation model of rolls with the kiss-rolls method, a gauge-meter model was put forward for plate thickness prediction. The prediction precision of thickness was greatly improved by the new gauge- meter model.

关键词： gauge meter influence function roll elastic deformation plate flattening

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