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MODELING OF MICROSTRUCTURAL EVOLUTION IN MICROALLOYED STEEL DURING HOT FORGING PROCESS

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Acta Metallurgica Sinica(English Letters) 2006年第4期19卷 279-286页

作者： j. Wang j. Chen z. zhao X.Y. ruan National Die ＆. Mold CAD Engineering Research Center Shanghai Jiaotong University Shanghai 200030 China

The microstractural evolution of microalloyed steel during hot forging process was investigated using physical simulation experiments. The dynamic recrystallized fraction was described by modifying Avrami＇s equation, the parameters of which were determined by single hit compression tests. Double hit compression tests were performed to model the equation describing the static recrystallized fraction, and the obtained predicted values were in good agreement with the measured values. Austenitic grain growth was modeled as： Dinc^5 = D0^5 ＋ 1.6 × 10^32t·exp （ -716870/RT ） using isothermal tests. Furthermore, an equation describing the dynamic recrystallized grain size was given as Ddyn=3771·z^-0.2. The models of microstructural evolution could be applied to the numerical simulation of hot forging.

关键词： microalloyed forging steel flow stress recrystallized fraction grain size

Discrete-frequency Convergence of Iterative Learning Control for Linear Time-invariant systems with Higher-order Relative Degree

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International journal of Automation and computing 2015年第3期12卷 281-288页

作者： Xiao-E ruan zhao-zhen Li z.z.Bien School of Mathematics and Statistics Xi an Jiaotong University Department of Electrical Engineering Korea Advanced Institute of Science and Technology

In this paper, a discrete-frequency technique is developed for analyzing sufficiency and necessity of monotone convergence of a proportional higher-order-derivative iterative learning control scheme for a class of linear time-invariant systems with higher-order relative degree. The technique composes of two steps. The first step is to expand the iterative control signals, its driven outputs and the relevant signals as complex-form Fourier series and then to deduce the properties of the Fourier coefficients. The second step is to analyze the sufficiency and necessity of monotone convergence of the proposed proportional higher-order-derivative iterative learning control scheme by assessing the tracking errors in the forms of Paserval s energy modes. Numerical simulations are illustrated to exhibit the validity and the effectiveness.

关键词： Iterative learning control monotone convergence discrete frequency-domain spectrum Fourier series Parseval s energy equality rel

The molecular pathogenic role of inflammatory stress in dysregulation of lipid homeostasis and hepatic steatosis

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Genes & Diseases 2014年第1期1卷 106-112页

作者： Yaxi Chen zac Varghese Xiong z.ruan Centre for Lipid Research Key Laboratory of Molecular Biology on Infectious DiseasesMinistry of EducationChongqing Medical UniversityChongqingChina john Moorhead Research Laboratory Centre for NephrologyUniversity College London Medical SchoolRoyal Free CampusLondonUK

Non-alcoholic Fatty Liver Disease(NAFLD)is becoming the leading cause of chronic liver injury in developed countries and *** systemic inflammation plays a decisive role and is fundamental in the progression of NAFLD from simple steatosis(SS)toward higher risk nonalcoholic steatohepatitis(NASH)***,the exact mechanisms by which inflammation leading to NASH are incompletely *** this review,we focus the role of the cross talk between inflammation and lipid homeostasis on the progression of NAFLD.

关键词： Ectopic lipid deposition Inflammation Lipid homeostasis Lipid redistribution Non-alcoholic fatty liver disease

Probing New Physics at future electron positron Higgs factories via e^+e^-→ zγ process

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Science China(Physics,Mechanics & Astronomy) 2021年第2期64卷 29-30页

作者： ManQi ruan Institute of High Energy Physics Chinese Academy of SciencesBeijing100049China

Direct searches and precision measurements are the two main complementary methods for identifying New Physics at *** next generation of e^+e^-Higgs factories,including CEPC,FCC-ee,ILC and CLIC,is designed to deliver m... 详细信息

关键词： processes. Higgs positron

THEORETICAL PREDICTION OF THE KINETICS CURVES OFPEARLITIC TRANSFORMATION IN HYPO-PROEUTECTOID STRUCTURAL STEELS

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Acta Metallurgica Sinica(English Letters) 1998年第3期11卷 215-224页

作者： z.G.Li H.B.Chang T.Y.Hsu z.Y.Xu X.Y.ruan Shanghai jiaotong Univ Shanghai China

Supposing carbon contents of ferrite phases in pearlite precipitating from austenite in multicomponent steel at temperature T and in Fe-C ystem at T' are the same the pearlite formation temperature diference, can be calculated from the FeX phase diagrams and the equilibrium temperature Al. Using Tp and Fe-C binary thermodynamic model, the driving forces for phase transformation from austenite to pearlite in multicomponent steels have been successfully calculated. Through the combination of simplified zener and Hillert's model for pearlite growth with johnson-Mehl equation, using data from known TTT diagrams, the interfacial energy parameter and activation energy for pearlite formation can be determined and expressed as functions of chemical composition in steels by regression analysis. The calculated starting curves of pearlitic transformation in some commercial steels agree well with the experimental data.

关键词： pearlite formation temperature difference interfacial energy parameter activation enerpy for pearlite transformation,johnson-Mehl equation

THEORETICAL PREDICTION OF PROEUTECTOID FERRITICTRANSFORMATION IN HYPO-PROEUTECTOID STRUCTRAL STEELS

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Acta Metallurgica Sinica(English Letters) 1998年第3期11卷 207-214页

作者： H.B.Chang z.G.Li T.Y.Hsu z.Y.Xu X.Y.ruan Shanghai Technical Coll of Metallurgy Shanghai China

Proeutectoid ferrite with carbon content xo precipitating from austenite in a multicomponent steel at temperature T is supposed to be equivalent to proeutectoid ferrite with the same carbon content precipitating from austenite in Fe-C binary system at temperature T'.is described as the temperature difference of proeutectiod ferrite formation, and can be calculated from the Fe-X diagrams and the equilibrium temperature A3. By introducing Tf and basing on the thermodynamic model for Fe-C binary alloy, the driving force for phase transformation from austenite to proeutectoid ferrite in multicomponent steels has been successfully calculated. Through the johnson-Mehl equation and using the data hem known TTT diagrams, the relationship between the chemical composition and the intedecial edenly packeter as well as activation energy for proeutectoid ferrite formation can be calculated. The starting curves of proeutectoid ferritic transformation calculated in this way in some hypo-proeutectoid structural steels agree well with the erperimental data.

关键词： proeutectoid ferrite formation temperature difference interfacial enerpy parameters activation energy for diffusion johnson-Mehl equation

Three-dimensional numerical study of supercritical pressure effect on heat transfer of cryogenic methane

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航空动力学报 2011年第7期26卷 1480-1487页

作者： ruan Bo MENG Hua School of Aeronautics and Astronautics Zhejiang University Hangzhou 310027 China)

A three-dimensional numerical study of the turbulent convective heat transfer of the cryogenic methane flowing inside a square engine cooling channel under supercritical pressures was systematically *** results indicate that increasing the fluid pressure results in enhanced heat transfer of the cryogenic methane under supercritical *** the pseudo-critical temperature under a corresponding supercritical pressure,drastic property variations cause heat transfer deterioration and sharp wall temperature increase at a high wall heat flux of 7MW/m2.A modified jackson and Hall heat transfer equation,which can be used for supercritical heat transfer calculations of the cryogenic methane,has been successfully established in this paper.

关键词： supercritical heat transfer supercritical pressure regenerative cooling cryogenic methane numerical study

Investigation of the methane hydrate surface area during depressurization-induced dissociation in hydrate-bearing porous media

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Chinese journal of Chemical Engineering 2021年第4期34卷 324-334页

作者： Xuke ruan Xiao-Sen Li Guangzhou Institute of Energy Conversion Chinese Academy of SciencesGuangzhou 510640China CAS Key Laboratory of Gas Hydrate Guangzhou 510640China

The surface area of hydrate during dissociation in porous media is essentially important for the kinetics of hydrate *** this study,the methane hydrate surface area was investigated by the comparison results of experiments and numerical simulations during hydrate decomposition in porous *** experiments of methane hydrate depressurizationinduced dissociation were performed in a 1D high pressure cell filled with glass beads,an improved and valid 1D corescale numerical model was developed to simulate gas *** conceptual models for hydrate dissociation surface area were proposed based on the morphology of hydrate in porous media,which formed the functional form of the hydrate dissociation surface area with porosity,hydrate saturation and the average radius of sand sediment *** the establishment of numerical model for depressurizationinduced hydrate dissociation in porous media,the cumulative gas productions were modeling and compared with the experimental data at the different hydrate *** results indicated that the proposed prediction equations are valid for the hydrate dissociation surface area,and the graincoating surface area model performs well at lower hydrate saturation for hydrate dissociation simulation,whereas at higher hydrate saturation,the hydrate dissociation simulation from the porefilling surface area model is more ***,the sensitivity analysis showed that the hydrate dissociation surface area has a significant impact on the cumulative gas production.

关键词： Surface area Methane hydrate Hydrate dissociation Hydrate morphology Depressurization

RESEARCH ON THE EVALUATION METHOD OF FRICTION AND LUBRICATION IN DEEP DRAWING

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Acta Metallurgica Sinica(English Letters) 2000年第2期13卷 439-445页

作者： D.N.He X.F.Yin H.z.Thao D.Lv X.Y.ruan j.L.Cheng j.Y.jiang Shanghai jiao Tong University National Die&Mold CAD E.R.CShanghai 200030China Shanghai Vopkswagen Automotive Company Ltd. Shanghai 201805China

The deformation characteristic of bland in deep drawing is discussed. It is pointed out that the friction and lubrication conditions in for drawing are different from that in mechanical motion or machine work or other plastic process. The common test methods in laboratories are analyzed. It shows that though all those test methods can test the friction coefficient, the probe test method is most suitable for the research of friction and lubrication and the process in deep drawing, for this method is identical with the actual work condition either from the test principle or deformation status of the blank. Last the successful application in the deep drawing simulator newly developed the the probe method are intro- duced in detail.

关键词： deep drawing probe test method friction and lubrication evaluation method