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Microstructure and Mechanical Properties of 50SiMnNiNb Steel by a Novel Quenching-Partitioning-Austempering Heat Treatment

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Chinese Journal of Mechanical Engineering 2009年第5期22卷 645-650页

作者： li Hongyan jin Xuejun School of Materials Science and Engineering Shanghai Jiao Tong University Shanghai 200240 China

For the purpose of reducing weight of steel parts, save raw materials and keep or even improve safety standards, the development of advanced high strength steels is increasingly demanded in the automotive industry and engineering applications. We have proposed a novel heat treatment （quenching-partitioning-austempering treatment, Q-P-A） to obtain steel parts with high strength and good ductility. The Q-P-A process is intended to produce microstructure consisted of carbon-depleted martensite, carbon-enriched retained austenite and nanostructured bainite. Quenching（Q） treatment fabricates mixed microstructure of carbon-supersaturated martensite and certain amounts of untransformed austenite. Partitioning（P） thermal treatment accomplishes fully diffusing of carbon from the supersaturated martensite phase to the untransformed austenite phase and enriching the amount of carbon in untransformed austenite. Further low-temperature austempering（A） process induces incredible thin bainite from the carbon-enriched untransformed austenite. A study of the microstructure and mechanical properties of 50SiMnNiNb steel subjected to the novel Q-P-A treatment is presented. Microstructure is assessed by optical microscope（OM）, field emission scanning electron microscope（FESEM） and transmission electron microscope（TEM）, and the corresponding mechanical properties are measured. The experimental results indicate that attractive mechanical properties of steels during the Q-P-A process are attributed to the complex multi-phase structure. Slender plates of bainite with 20-40 nm thick are generated in the medium carbon steel. Meanwhile, with increasing of the volume fraction of nanostructured bainite, yield strength of steel parts is increased with little degradation of ultimate tensile strength. In this paper, a novel quenching-partitioning-austempering heat treatment is proposed, and the attractive mechanical properties of steels are obtained during the Q-P-A process.

关键词： heat treatment quenching-partitioning-austempering martensite retained austenite nanostructured bainite

Constructions on Approximately Mutually Unbiased Bases by Galois Rings

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Journal of Systems Science & Complexity 2015年第6期28卷 1440-1448页

作者： li jin FENG Keqin School of Mathematics Hefei University of Technology Department of Mathematical Sciences Tsinghua University

Several new series of approximately mutually unbiased bases are constructed by using Gauss sums and Jacobi sums over Galois rings GR(p2, r), and the tensor method.

关键词： MUB Galois rings Gauss sums Jacobi sums tensor method

Blood nitric oxide data reveals a new adaptive strategy of Tibetans to hypobaric hypoxia

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National Science Review 2018年第4期5卷 530-531页

作者： li jin School of life Sciences Fudan University NSR

The study of‘Blunted nitric oxide regulation in Tibetans under high altitude hypoxia’provides important physiological data of native Tibetans,which has been interpreted as a previously unknown mechanism for the adaptation of Tibetans to highaltitude hypoxia[1].Tibetans are among the world’s high-altitude natives(the other example is Andeans)who have developed genetic adap-

关键词： Blood nitric oxide data reveals a new adaptive strategy of Tibetans to hypobaric hypoxia

Morphology evolution of two-phase Cu-Ag alloys under different conditions

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2009年第3期10卷 458-463页

作者： jin-li HU jin-dong ZHANG liang MENG Department of Materials Science and Engineering Zhejiang University Hangzhou 310027 China Xingtai Xinhui Copper Special Wire. Co. Ltd. Xingtai 055550 China

Cu-Ag filamentary microcomposites with different Ag contents were prepared by cold drawing and intermediate heat treatments. The microstructure characterization and filamentary distribution were observed for two-phase alloys under different conditions. The effect of heavy drawing strain on the microstructure evolution of Cu-Ag alloys was investigated. The results show that the microstructure components consist of Cu dendrites, eutectic colonies and secondary Ag precipitates in the alloys containing 6%-24% （mass fraction） Ag. With the increase in Ag content, the eutectic colonies in the microstructure increase and gradually change into a continuous net-like distribution. The Cu dendrites, eutectic colonies and secondary Ag precipitates are elongated in an axial direction and developed into the composite filamentary structure during cold drawing deformation. The eutectic colonies tend to evolve into filamentary bundles. The filamentary diameters decrease with the increase in drawing strain degree for the two-phase alloys, in particular for the alloys with low Ag content. The reduction in filamentary diameters becomes slow once the drawing strain has exceeded a certain level.

关键词： Cu-Ag alloy Microstructure Strain Filamentary composite

ADAPTIVE TRIMMED MEAN AS A LOCATION ESTIMATE

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Journal of Systems Science & Complexity 2012年第5期25卷 973-986页

作者： Siming li Yong li Jiao jin Department of Statistics and Financial Mathematics School of Mathematical SciencesKey Laboratory of Mathematics and Complex SystemsMinistry of EducationBeijing Normal University

The trimmed mean is one of the most common estimators of location for symmetrical distributions, whose effect depends on whether the trim rate matches the proportion of contaminated data. Based on the geometric characteristics of the curve of the trimmed variance function, the authors propose two kinds of adaptive trimmed mean algorithms. The accuracy of the estimators is compared with that of other often-used estimates, such as sample mean, trimmed mean, trimean, and median, by means of simulation method. The results show that the accuracy of the adaptive derivative optimization trimmed mean method is close to the optimum performance in case of medium contamination （the contamination rate is less than 50%）. Under high contamination situation （the contamination rate equals 8070）, the performance of the estimates is comparable to that of the median and is superior to other counterparts.

关键词： Adaptive location parameter robust trimmed mean.

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快中子诱发蛇纹石混凝土力学性能退化研究

A Criterion for the Generalized Riemann Hypothesis

工程力学 2025年第1期42卷 32-43页

作者：陈凤娟高成琛金浏杜修力北京工业大学城市减灾与防灾防护教育部重点实验室北京100124

基于三维细观数值模拟方法，考虑快中子辐照(MeV>1.0)诱发的温度与骨料膨胀联合作用对混凝土力学行为及破坏形态的影响规律，该文提出了可有效预测辐照混凝土残余力学性能的二阶段数值模型计算方法，开展了蛇纹石骨料混凝土力学性能退... 详细信息

基于三维细观数值模拟方法，考虑快中子辐照(MeV>1.0)诱发的温度与骨料膨胀联合作用对混凝土力学行为及破坏形态的影响规律，该文提出了可有效预测辐照混凝土残余力学性能的二阶段数值模型计算方法，开展了蛇纹石骨料混凝土力学性能退化研究，并借助物理试验进行了模型验证。此外，基于数值模拟结果，提出了蛇纹石骨料膨胀作用下混凝土力学响应及残余力学性能的理论计算公式。该文提出的三维细观数值模型旨在为评估辐照混凝土力学响应及残余力学性能提供有效工具，为揭示辐照混凝土力学性能退化机理提供分析工具，为进行辐照混凝土基准研究提供理论依据，后期可为核反应堆混凝土防护墙延寿评估提供一定的理论指导。

关键词：快中子辐照诱导骨料膨胀力学性能三维细观数值模型蛇纹石骨料混凝土

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Acta Mathematica Sinica,English Series 2009年第11期25卷 1875-1880页

作者： jin Hong li School of Mathematics Shandong University Ji'nan Shandong 250100 P. R. China College of Mathematics and Physics Shandong Institute of Light Industry Ji'nan Shandong 250353 P. R. China

In this paper, we study the automorphic L-functions attached to the classical automorphic forms on GL（2）, i.e. holomorphic cusp form. And we also give a criterion for the Generalized Riemann Hypothesis （GRH） for t... 详细信息

关键词： GRH L-function holomorphic cusp form

A double-edged sword of immuno-microenvironment in cardiac homeostasis and injury repair

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Signal Transduction and Targeted Therapy 2021年第3期6卷 779-794页

作者： Kang Sun Yi-yuan li jin jin MOE Laboratory of Biosystem Homeostasis and Protection and Life Sciences InstituteZhejiang UniversityHangzhou 310058China Key Laboratory for Developmental Genes and Human Disease Ministry of EducationInstitute of Life SciencesJiangsu Province High-Tech Key Laboratory for Bio-Medical ResearchSoutheast UniversityNanjing 210096China Sir Run Run Shaw Hospital College of Medicine Zhejiang UniversityHangzhou 310016China

The response of immune cells in cardiac injury is divided into three continuous phases:inflammation,proliferation and *** kinetics of the inflammatory and proliferation phases directly influence the tissue *** cardiac homeostasis,cardiac tissue resident macrophages(cTMs)phagocytose bacteria and apoptotic ***,NK cells prevent the maturation and transport of inflammatory *** cardiac injury,cTMs phagocytose the dead cardiomyocytes(CMs),regulate the proliferation and angiogenesis of cardiac progenitor *** cells prevent the cardiac fibrosis,and promote vascularization and *** 1 macrophages trigger the cardioprotective responses and promote tissue fibrosis in the early ***,type 2 macrophages promote cardiac remodeling and angiogenesis in the late *** macrophages and neutrophils firstly lead to chronic inflammation by secreting proinflammatory cytokines,and then release anti-inflammatory cytokines and growth factors,which regulate cardiac *** this process,dendritic cells(DCs)mediate the regulation of monocyte and macrophage *** eosinophils and Mast cells(MCs)release some mediators which contribute to coronary vasoconstriction,leukocyte recruitment,formation of new blood vessels,scar *** adaptive immunity,effector T cells,especially Th17 cells,lead to the pathogenesis of cardiac fibrosis,including the distal fibrosis and scar *** protectors,Treg cells,inhibit reduce the inflammatory response,then directly trigger the regeneration of local progenitor cell via IL-10.B cells reduce myocardial injury by preserving cardiac function during the resolution of inflammation.

关键词： cardiac homeostasis inflammation

A Hilbert-Schmidt integral operator and the Weil distribution

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Science China Mathematics 2023年第1期66卷 91-114页

作者： Xian-jin li Department of Mathematics Brigham Young UniversityProvoUT 84602USA

In this paper,a positive operator is *** is shown that the product of this positive operator and the convolution operator is a trace class Hilbert-Schmidt integral operator and has nonnegative eigenvalues.A formula is given for the trace of this product *** seems that this product operator is the closest trace class integral operator which has nonnegative eigenvalues and is related to the Weil distribution in the context of Connes’program for the Riemann hypothesis.A relation is given between the trace of the product operator and the Weil distribution.

关键词： eigenvalue explicit formula positivity trace of the operator