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Reaction mechanisms between molten CaF2-based slags and molten 9CrMoCoB steel

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International Journal of Minerals,Metallurgy and Materials 2020年第5期27卷 611-619页

作者： Lei-zhen Peng Zhou-hua jiang Xin Geng School of Metallurgy Northeastern UniversityShenyang 110819China

Investigating the reaction mechanism between slag and 9CrMoCoB steel is important to develop the proper slag and produce qualified ingots in the electroslag remelting(ESR) process. Equilibrium reaction experiments between molten 9CrMoCoB steel and the slags of 55 wt%CaF2–20 wt%CaO–3 wt%MgO–22 wt%Al2O3–xwt%B2O3(x = 0.0, 0.5, 1.0, 1.5, 2.0, 3.0) were conducted. The reaction mechanisms between molten 9 CrMoCoB steel and the slags with different B2O3 contents were deduced based on the composition of the steel and slag samples at different reaction times. Results show that B content in the steel can be controlled within the target range when the B2O3 content is 0.5 wt% and the FeO content ranges from 0.18 wt% to 0.22 wt% in the slag. When the B2O3 content is ≥1 wt%, the reaction between Si and B2O3 leads to the increase of the B content of steel. The additions of SiO2 and B2O3 to the slag should accord to the mass ratio of [B]/[Si] in the electrode, and SiO2 addition inhibits the reaction between Si and Al2O3.

关键词： 9CrMoCoB electroslag remelting B2O3 thermodynamic calculation reaction mechanism

Inferring the Physics of Structural Evolution of Multicomponent Polymers via Machine-Learning-Accelerated Method

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Chinese Journal of Polymer Science 2023年第9期41卷 1377-1385,I0006页

作者： Kai-hua Zhang Ying jiang Liang-Shun Zhang School of Chemistry Center of Soft Matter Physics and Its ApplicationsBeihang UniversityBeijing100191China Shanghai Key Laboratory of Advanced Polymeric Materials School of Materials Science and EngineeringEast China University of Science and TechnologyShanghai200237China

Dynamic self-consistent field theory(DSCFT)is a fruitful approach for modeling the structural evolution and collective kinetics for a wide variety of multicomponent ***,solving a set of DSCFT equations remains daunting because of high computational ***,a machine learning method,integrating low-dimensional representations of microstructures and long short-term memory neural networks,is used to accelerate the predictions of structural evolution of multicomponent *** is definitively demonstrated that the neural-network-trained surrogate model has the capability to accurately forecast the structural evolution of homopolymer blends as well as diblock copolymers,without the requirement of“on-the-fly”solution of DSCFT ***,the data-driven method can also infer the latent growth laws of phase-separated microstructures of multicomponent polymers through simply using a few of time sequences from their past,without the prior knowledge of the governing *** study exemplifies how the machine-learning-accelerated method can be applied to understand and discover the physics of structural evolution in the complex polymer systems.

关键词： Machine learning Dynamic self-consistent field theory Structural evolution Block copolymers Homopolymer blends

Twisted Helical Microfibers by Hierarchical Self-Assembly of an Aromatic Oligoamide Foldamer

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Chinese Journal of Chemistry 2013年第5期31卷 651-656页

作者： Quan Gan Ying Wang hua jiang College of Chemistry Beijing Normal University Beijing 100875 China Beijing National Laboratory for Molecular Sciences CAS Key Laboratory of Photochemistry Institute of Chemistry Chinese Academy of Sciences Beijing 100190 China

A series of aromatic oligoamide foldamers based on 8-fluoro amino-quinoline carboxyl acid have been synthe- sized and characterized. Studies show that these foldamers self-assemble to form well-defined twisted helical mi- crofibers in chloroform-methanol （1 ： 1, V/V） binary solvent due to the intermolecular π-π stacking and van der Waals forces of aliphatic chains, which are supported by SEM, TEM and XRD. It is also revealed that the assembly morphologies show strong dependence on the length of alkyl chains.

关键词： foldamer self-assembly microfiber hydrogen bonding aromatic stacking

Evaluation of monthly turbulent heat fluxes from WHOI analysis and NCEP reanalysis in the tropical Atlantic

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Acta Oceanologica Sinica 2005年第5期24卷 14-26页

作者： jiang hua WANG Hui WU Dexing Institute of Climate System Chinese Academy of Meteorological Sciences Beijing 100081 China Chinese Academy of Meteorological Sciences Beijing 100081 China Institute of Physical Oceanography Ocean University of China Qingdao 266003 China

The biases and their sources in monthly turbulent heat fluxes from the Woods Hole Oceanographic Institution （WHOI） analysis, and the National Centers for Environmental Prediction-National Center for Atmospheric Research reanalyses 1 and 2 （NCEPI and NCEP2） are checked in the climatically representative regions in the tropical Atlantic using the fluxes from the Southampton Oceanographic Centre （SOC） and the pilot research moored array in the tropical Atlantic （PIRATA） as references. For the WHOI analysis, the biases in turbulent heat fluxes mainly exist in equatorial regions which are due to the overestimated sea surface temperature and the underestimated 2 m air humidity. For the NCEP2 reanalysis, the maximum biases, about （40±5） W/m^2, exist in southeast and northeast trade wind regions, which are mainly caused by the flux algorithm used because the biases in wind speed and air-sea humidity difference are relatively small. In the equatorial regions, the flux biases in the NCEP2 derived from both flux-related basic variables and algorithm are equally large. Although the estimations of time series trends and air-sea humidity difference of the NCEPI are improved greatly in the NCEP2, the biases of latent heat flux in the NCEP2 are about 20 W/m^2 greater than those from the NCEP1 in the trade wind regions. The result shows that the climatologies and monthly variabilities of the turbulent heat fluxes from the WHOI are more accurate than those from the NCEP1 and NCEP2 in the tropical Atlantic, especially on outside of the equatorial regions.

关键词： turbulent heat fluxes evaluation the tropical Atlantic

Remarks on One-Dimensional Compressible Navier-Stokes Equations with Density-Dependent Viscosity and Vacuum

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Acta Mathematica Sinica,English Series 2010年第10期26卷 2015-2030页

作者： Zhen hua GUO Chang jiang ZHU Center for Nonlinear Studies and Department of Mathematics Northwest University Xi'an 710069 P. R. China Laboratory of Nonlinear Analysis Department of Mathematics Central China Normal University Wuhan 4300794 P. R. China

The Navier-Stokes system for one-dimensional compressible fluids with density-dependent viscosities when the initial density connects to vacuum continuously is considered in the present paper. When the viscosity coefficient u is proportional to pθ with 0 〈 θ 〈 1, the global existence and the uniqueness of weak solutions are proved which improves the previous results in [Vong, S. W., Yang, T., Zhu, C. J.： Compressible Navier-Stokes equations with degenerate viscosity coefficient and vacuum II. J. Differential Equations, 192（2）, 475-501 （2003）]. Here p is the density. Moreover, a stabilization rate estimate for the density as t → ＋∞ for any θ 〉 0 is also given.

关键词： Compressible Navier-Stokes equations density-dependent viscosity vacuum asymptotic behavior

Singularity analysis of Jeffcott rotor-magnetic bearing with time delays

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Applied Mathematics(A Journal of Chinese Universities) 2012年第4期27卷 419-427页

作者： XU Xiu-yan jiang Wei-hua Department of Mathematics Heilongjiang Institute of Science and TechnologyHarbin 150027China Department of Mathematics Harbin Institute of TechnologyHarbin 150001China

A Jeffcott rotor-magnetic bearing with time delays is investigated in this paper. Firstly, it is found that the characteristic equation of the system satisfies the conditions of the singularity. Secondly, the center manifold reduction and normal form are employed to study the bifurcation from simple zero and zero-purely imaginary singularities. The results of this paper will help to understand the influence of the time delays in feedback loop on the dynamics of rotor-magnetic bearing system.

关键词： Jeffcott rotor-magnetic bearing time delay singularity normal form.

Method for Improving Transverse Wall Thickness Precision of Seamless Steel Tube Based on Tube Rotation

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Journal of Iron and Steel Research International 2015年第10期22卷 924-930页

作者： Yong-zheng jiang hua-ping TANG State Key Laboratory of High Performance Complex Manufacturing Central South University

The tube rotation method （TRM） refers to the rotational movement of steel tube about its axis as well as translation in rolling direction in stretch reducing rolling process. The influence of the TRM on transverse wall thickness precision of seamless steel tube was studied. Thickness distribution of the TRM was obtained by superimposing the thickened amount of single pass rolling. Results show that the TRM can effectively improve the evenness of thickness distribution. In order to analyze the influence mechanism of the TRM, the finite element method was adopted to simulate the thickness distribution in stretch reduction process. Results show that the TRM changes the roundtrip flow between two fix places of conventional stretch reducing and inhibits the directional accumulation of metal. In addition, the TRM has a correction effect on thickness cusp. All these advantages of the TRM help to improve the transverse wall thickness precision of seamless steel tube.

关键词： seamless tube stretch reducing transverse unevenness tube rotation method

Effective Thermal Conductivity for 3D Five-Directional Braided Composites Based on Microstructural Analysis

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Transactions of Nanjing University of Aeronautics and Astronautics 2019年第1期36卷 128-138页

作者： ZHAO Xiao MAO Junkui jiang hua Key Laboratory of Aerospace Power System College of Energy and Power EngineeringNanjing University of Aeronautics and Astronautics Cummins(China) Investment Co. Ltd. Commercial Aircraft Corporation of China Ltd.

A method for predicting effective thermal conductivities(ETCs) of three-dimensional five-directional(3D5D) braided composites is presented. The effective thermal conductivity prediction method contains a digital image processing technology. Multiple scanning electron microscopy(SEM)images of composites are analyzed to obtain actual microstructural features. These actual microstructural features of 3D5D braided composites are introduced into representative volume element(RVE) modeling. Apart from applying actual microstructural features,compression effects between yarns are considered in the modeling of RVE,making the RVE more realistic. Therefore,the ETC prediction method establishes a representative unit cell model that better reflects the true microstructural characteristics of the 3D5D braided composites. The ETCs are predicted with the finite element method. Then thermal conductivity measurements are carried out for a 3D5D braided composite *** comparing the predicted ETC with the measured thermal conductivity, the whole process of the ETC prediction method is proved to be effective and accurate,where a relative error of only 2.9 % is ***,the effects of microstructural features are investigated,indicating that increasing interior braiding angles and fiber fill factor can lead to higher transverse ETCs. Longitudinal ETCs decrease with increasing interior braiding angles,but increase with increasing fiber fill factor. Finally,the influence of variations of microstructure parameters observed in digital image processing are investigated. To explore the influence of variations in microstructural features on variations in predicted ETCs,the actual probability distributions of microstructural features obtained from the 3D5D braided composite sample are introduced into the ETC investigation. The results show that,compared with the interior braiding angle,variations in the fiber fill factor exhibit more significant effects on variations in ETCs.

关键词： effective thermal conductivity digital image processing variation 3D five-directional braided composites

Seasonal variability of turbulent heat fluxes in the tropical Atlantic Ocean based on WHOI flux product

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Acta Oceanologica Sinica 2007年第5期26卷 1-11页

作者： jiang hua WANG Hui WU Dexing Institute of Climate System Chinese Academy of Meteorological Sciences Beijing 100081 China Institute of Physical Oceanography Ocean University of China Qingdao 266003 China

The mean seasonal variability of turbulent heat fluxes in the tropical Atlantic Ocean is examined using the Woods Hole Oceanographic Institution （WHOI） flux product. The most turbulent heat fluxes occur during winter seasons in the two hemispheres, whose centers are located at 10° -20°N and 5° 15°S respectively. In climatological ITCZ, the turbulent heat fluxes are the greatest from June to August, and in equatorial cold tongue the turbulent heat fluxes are the greatest from March to May. Seasonal variability of sensible heat flux is smaller than that of latent heat flux and mainly is dominated by the variations of air-sea temperature difference. In the region with larger climatological mean wind speed （air-sea humidity difference）, the variations of air-sea humidity difference （wind speed） dominate the variability of latent heat flux. The characteristics of turbulent heat flux yielded from theory analysis and WHOI dataset is consistent in physics which turns out that WHOI＇ s flux data are pretty reliable in the tropical Atlantic Ocean.

关键词： turbulent heat fluxes seasonal variation tropical Atlantic