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A Class of Backward Doubly Stochastic Differential Equations with Discontinuous Coefficients

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Acta Mathematicae Applicatae Sinica 2014年第4期30卷 965-976页

作者： qing-feng zhu Yu-feng SHI School of Mathematic and Quantitative Economics Shandong University of Finance and Economics Institute for Financial Studies and School of Mathematics Shandong University School of Statistics Shandong University of Finance and Economics

In this work the existence of solutions of one-dimensional backward doubly stochastic differential equations （BDSDEs） with coefficients left-Lipschitz in y （may be discontinuous） and Lipschitz in z is studied. Als... 详细信息

关键词： backward doubly stochastic differential equations backward stochastic integral comparisontheorem

Infinite Horizon Forward-Backward Doubly Stochastic Differential Equations and Related SPDEs

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Acta Mathematicae Applicatae Sinica 2021年第2期37卷 319-336页

作者： qing-feng zhu Liang-quan ZHANG Yu-feng SHI School of Mathematics and Quantitative Economics Shandong University of Finance and EconomicsandShandong Key Laboratory of Blockchain FinanceJinan 250014China Institute for Financial Studies and School of Mathematics Shandong UniversityJinanChina School of Science Beijing University of Posts and TelecommunicationsBeijing 100876China

A type of infinite horizon forward-backward doubly stochastic differential equations is *** some monotonicity assumptions,the existence and uniqueness results for measurable solutions are established by means of homotopy method.A probabilistic interpretation for solutions to a class of stochastic partial differential equations combined with algebra equations is given.A significant feature of this result is that the forward component of the FBDSDEs is coupled with the backward variable.

关键词： infinite horizon forward-backward doubly stochastic differential equations homotopy stochastic partial differential equation

Shining in the dark:the big world of small peptides in plants

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aBIOTECH 2023年第3期4卷 238-256页

作者： Yan-Zhao feng qing-feng zhu Jiao Xue Pei Chen Yang Yu Guangdong Key Laboratory of Crop Germplasm Resources Preservation and Utilization Key Laboratory of South China Modern Biological Seed IndustryMinistry of Agriculture and Rural AffairsAgro-Biological Gene Research CenterGuangdong Academy of Agricultural SciencesGuangzhou 510640China

Small peptides represent a subset of dark matter in plant *** differential expression patterns and modes of action,small peptides act as important regulators of plant growth and devel*** the past 20 years,many small peptides have been identified due to technical advances in genome sequencing,bioinformatics,and chemical *** this article,we summarize the classifi-cation of plant small peptides and experimental strategies used to identify them as well as their potential use in agronomic *** review the biological functions and molecular mechanisms of small peptides in plants,discuss current problems in small peptide research and highlight future research directions in this *** review provides crucial insight into small peptides in plants and will contribute to a better understanding of their potential roles in biotechnology and agriculture.

关键词： Small peptide Biological function Regulatory mechanism Crop improvement

Structures and macrosegregation of a 2024 aluminum alloy fabricated by direct chill casting with double cooling field

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China Foundry 2022年第1期19卷 1-8页

作者： Cheng zhu Zhi-hao Zhao qing-feng zhu Gao-song Wang Yu-bo Zuo Gao-wu Qin Research Center for Metallic Wires School of Materials Science and EngineeringNortheastern UniversityShenyang 110819China Key Laboratory of Electromagnetic Processing of Materials Ministry of EducationNortheastern UniversityShenyang 110819China Key Laboratory of Anisotropy and Texture of Materials Ministry of EducationNortheastern UniversityShenyang 110819China

Central region coarse grains and centerline segregation are common defects in aluminum ingots fabricated by direct chill(DC)casting.A double cooling field was introduced into the DC casting process to reduce these defects,whereby the external cooling was supplied by the mold and water jets,and intercooling was achieved by inserting a rod of the same alloy into the molten pool along the central axis of the *** than forming a good metallurgical interface during solid-liquid compound casting,in the present work,the purpose of inserting the rod is to enforce internal cooling and consequently decrease the sump ***,the insertion provides more nucleation sites with the unmoltenα-Al *** structure and the macrosegregation of 2024 Al alloy ingots prepared by DC casting with and without the inserts were *** show that when the inserting position is 50 mm above the upper edge of the graphite ring,significant grain refinement in the central region of the ingot and a reduced centerline segregation are achieved.

关键词： aluminum alloy direct chill casting double cooling field grain refinement macrosegregation

As-cast structure of DC casting 7075 aluminum alloy obtained under dual-frequency electromagnetic field

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International Journal of Minerals,Metallurgy and Materials 2014年第2期21卷 150-154页

作者： Zhi-hao Zhao Zhen Xu Gao-song Wang qing-feng zhu Jian-zhong Cui The Key Laboratory of the Ministry of Education of China for Electromagnetic Processing of Materials Northeastern University

We have experimentally determined the as-cast structures of semi-continuous casting 7075 aluminum alloy obtained in the pres-ence of dual-frequency electromagnetic field. Results suggest that the use of dual-frequency electromagnetic field during the semi-continuous casting process of 7075 aluminum alloy ingots reduces the thickness of the surface segregation layer, increases the height of the melt menis-cus, enhances the surface quality of the ingot, and changes the surface morphology of the melt pool. Moreover, low-frequency electromag-netic field was found to show the most obvious influence on improving the as-cast structure because of its high permeability in conductors.

关键词： electromagnetic fields: semi-continuous casting aluminum alloys as-cast structure

The potential of FAST in detecting celestial hydroxyl masers and related science topics

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Research in Astronomy and Astrophysics 2019年第2期19卷 65-70页

作者： Jiang-Shui Zhang Di Li Jun-Zhi Wang qing-feng zhu Juan Li Center for Astrophysics Guangzhou University National Astronomical Observatories Chinese Academy of Sciences Key Laboratory of FAST National Astronomical Observatories Chinese Academy of Sciences School of Astronomy and Space Science University of Chinese Academy of Sciences Shanghai Astronomical Observatory Chinese Academy of Sciences University of Science and Technology of China Chinese Academy of Science

The Five-hundred-meter Aperture Spherical radio Telescope(FAST) will make contributions to studies of Galactic and extragalactic masers. This telescope, with construction finished and now undergoing commissioning, has an innovative design that leads to the highest sensitivity of any single dish radio telescope in the world. FAST's potential for OH megamaser research is discussed, including the sky density of masers detectable in surveys. The scientific impact expected from FAST maser studies is also discussed.

关键词： masers instrumentation:sensitivity instrumentation:detectability sky density galaxies:interactions

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

Investigation on Reaction Interface between the Aluminum and K2ZrF6 by Freezing the Molten Salt Reaction

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Acta Metallurgica Sinica(English Letters) 2017年第5期30卷 433-437页

作者： qing-feng zhu Fei Li Lei Li Wen-Jing Wang Gao-Song Wang Jian-Zhong Cui Key Laboratory of Electromagnetic Processing of Materials Ministry of EducationNortheastern UniversityShenyang 110819China School of Materials Science and Engineering Northeastern UniversityShenyang 110819China

A reaction interface between the aluminum and K_2ZrF_6 during molten salt reaction process was frozen by quenching the mold in water, and the interface structure was analyzed to determine the formation process of Al_3Zr. Results show that a clear conical interface existed between the K_2ZrF_6 and aluminum. A zirconium accumulation layer with the thickness of about 2–3 lm was formed at the aluminum side of the interface. Many initially formed Al_3Zr particles（with the size of 0.4–16 lm） distributed in this layer, most of which located at the interface. The morphology of Al_3Zr particles is closely related with their size. For the size of 0.4–1 lm, the Al_3Zr appeared as globular and ellipsoid shapes. When it grew to the size of 1–2 and 2–16 lm, it exhibited the rule cube shape, and rule cuboids shape, respectively.

关键词： Molten salt reaction Interface Aluminum Al3Zr particle Solidification

Dynamic and Static Aging Precipitation of β-Mg_(17)Al_(12) in the AZ80 Magnesium Alloy During Multi-directional Forging and Subsequent Aging

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Acta Metallurgica Sinica(English Letters) 2017年第10期30卷 941-948页

作者： qing-feng zhu Gao-Song Wang En-Ge Zhang Fan-Zheng Liu Zhi-Qiang Zhang Jian-Zhong Cui Key Laboratory of Electromagnetic Processing of Materials Ministry of EducationNortheastern University School of Materials Science and Engineering Northeastern University

Dynamic and static aging precipitation of Mg17Al12 phases in AZ80 magnesium alloy was studied by multidirectional forging（MDF） with decreasing temperatures from 410 to 300 ℃ and subsequent aging process. The results show that the morphology of the β-Mg17Al12 phases during forging process dynamically precipitates and aging process（statically precipitation） exhibited granular and laminar shapes, respectively. During the MDF, the inhomogeneous dynamic precipitation of the β-Mg17Al12 phases results in the uniformity on grain size, which is fine in the area with many granular Mg17Al12 phases but the grain is still coarse where there is no Mg17Al12 phases. During the aging process, the morphology of newly formed β-Mg17Al12 phases depends on the structural character of the forged sample. The newly precipitated β-Mg17Al12 phases are coarse laminar and needle-like shape in area with coarse grain. While, the fine newly precipitated β-Mg17Al12 phases are fine granular and needle-like in the area with fine grain.

关键词： Dynamic strain aging Precipitation AZ80 magnesium alloy Multi-directional forging Dynamic recrystallization