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Effect of bainite microstructure during two-step quenching and partitioning process on strength and toughness properties of a 0.3%C bainitic steel

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Journal of Iron and Steel Research International 2018年第2期25卷 235-242页

作者： Cheng-hui Su qiang-guo Li xue-fei Huang Wei-gang Huang College of Materials Science and Engineering SichuanUniversity Chengdu 610065 Sichuan China

The effect of bainite transformation and microstructure on the mechanical properties in 0.3%C bainitic steel was investigated via the heat treatment process of quenching at higher initial temperature and partitioning below martensite-start temperature. The results show that bainite transformation takes place with the partitioning time increasing during partitioning below martensite-start temperature. The microstructure of samples treated by this two-step quenching and partitioning process consists of lath bainite, lath martensite and retained austenite. This kind of multiphase microstructure exhibits better strength of 1420 MPa, ductility of 21.8 % and the product of strength and elongation of 30.8 GPa%. Furthermore, the excellent impact toughness of 103 J is exhibited by partitioning at 280 ℃ for 3 h. In addition, the coalescence of bainite platelets was found in the sample treated by partitioning for 8 h, leading to the deterioration of toughness.

关键词： Quenching and partitioning Bainitic steel Impact toughness Coalesced bainite

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连铸圆坯中夹杂物的综合测定与分析

钢铁 2010年第7期45卷 41-46页

作者：王雪峰彭其春衡阳钢管(集团)有限公司技改工程部湖南衡阳421001 武汉科技大学材料与冶金学院湖北武汉430081

为了对钢中夹杂物的来源和性质有一个深入广泛的认识,开展了连铸圆坯夹杂物的检测与分析研究。利用金相显微镜、大样电解、扫描电镜及常规化学分析方法对连铸圆坯生产过程中的夹杂物进行了综合测定与分析,分析了夹杂物的来源、形态及分... 详细信息

为了对钢中夹杂物的来源和性质有一个深入广泛的认识,开展了连铸圆坯夹杂物的检测与分析研究。利用金相显微镜、大样电解、扫描电镜及常规化学分析方法对连铸圆坯生产过程中的夹杂物进行了综合测定与分析,分析了夹杂物的来源、形态及分布。试验结果表明,应该实施增加脱氧用铝量、使用活性石灰、改进中间包保护渣等措施。

关键词：连铸圆坯夹杂物分析

Circularly polarized luminescence of lanthanide complexes:From isolated individuals,discrete oligomers,to hierarchical assemblies

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InfoMat 2023年第3期5卷 58-101页

作者： Yuan Zhong Zhennan Wu Yu Zhang Bin Dong xue Bai State Key Laboratory of Integrated Optoelectronics College of Electronic Science and EngineeringJilin UniversityChangchunthe People's Republic of China Key Laboratory of New Energy and Rare Earth Resource Utilization of State Ethnic Affairs Commission Key Laboratory of Photosensitive Materials&Devices of Liaoning ProvinceSchool of Physics and Materials EngineeringDalian Nationalities UniversityDalianthe People's Republic of China

Circularly polarized luminescence(CPL)is the emission featured spatial orientation equivalent to circular *** to the unique magnetic dipole-allowed but electric-dipole-forbidden 4f→4f transitions,chiral lanthanide complexes have been recognized as ideal candidates to achieve unprecedented luminescence dissymmetry factor(glum).Their inherent electric-dipole-forbidden transition can be partly allowed,through the rational design of coordination ligands to lower the surrounding symmetry,further endowing them with relatively high quantum yields(QYs).Moreover,the blossom of supramolecular chemistry in lanthanide complexes allows for the construction of discrete oligomers and hierarchical assemblies,rendering them with enhanced chiroptical ***,we deploy this review by summarizing recent advances in the chiroptical properties of lanthanide complexes,spanning multiple scales from isolated mononuclear individuals,discrete polynuclear oligomers,to infinite hierarchical *** first introduce the basic concept and several important parameters for the assessment of CPL ***,isolated mononuclear lanthanide complexes coordinated with different types of antennas,along with the unique chirality transfer and induction in achiral lanthanide complexes were ***,the systematical discussion on chiroptical properties in discrete polynuclear lanthanide oligomers and infinite hierarchical lanthanide assemblies was ***,the state-of-the-art applications of CPL-active lanthanide complexes were *** end up this review with the conclusion and prospects,involving the rational design of ligands,directed and hierarchically precise self-assembly,and extending applications of chiral lanthanide complexes.

关键词： circularly polarized luminescence chiroptical property lanthanide complexes self-assembly

Effect of Thermal Cycling on Properties and Microstructure of SnAgCuCe Soldered Joints in QFP Devices

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Chinese Journal of Mechanical Engineering 2011年第4期24卷 561-566页

作者： ZHANG Liang xue Songbai GAO Lili ZENG Guang YU Shenglin SHENG Zhong College of Materials Science and Technology Nanjing University of Aeronautics and Astronautics Nanjing 210016 China School of Mechanical ＆ Electrical Engineering Xuzhou Normal University Xuzhou 221116 China The 14th Research Institute China Electronics Technology Group Corporation Nanjing 210013 China

Increasing global concern about the environment is bringing regulatory （European directives） and consumer （＂green products＂） pressure on the electronics industry in Europe and Japan to reduce or completely eliminate the use of lead （Pb） in products. Among all lead-free solder alloys, SnAgCu solder system, which has better thermo-mechanical properties compared with those of SnPb solder, is proven to be one of the promising candidates for electronic assembly. Previous work also revealed that adding a small amount of rare earth Ce into SnAgCu solder can visibly improve the properties and inhibit the excessive growth of the intermetallic compound layer. Thermal fatigue properties of SnAgCuCe soldered joints in QFP devices under thermal conditions have been investigated by finite element method and experiments. Based on creep model of low stress and high stress, corresponding creep subroutine was established for simulating the stress and strain response of SnAgCuCe soldered joint from -55 ℃ to 125 ℃, and fatigue life was calculated using creep fatigue life prediction equation. Moreover, thermal cycling experiments were conducted, the experimental results were found to be close to the simulated results. In addition, the tensile force of SnAgCuCe soldered joints decreased with increasing number of thermal cycles, and the fracture mechanism transformed from toughness fracture to brittle intergranular fracture. Moreover the tensile force changes and fracture microstructure evolution could benefit the quantitative evaluations of the mechanical performances of lead-free soldered joints under thermal cycling loadings.

关键词： finite element method creep equation thermal cycling fatigue life

A survey on the network models applied in the industrial network optimization

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Science China(Information Sciences) 2024年第2期67卷 85-103页

作者： Chao DONG Xiaoxiong XIONG qiulin xue Zhengzhen ZHANG Kai NIU Ping ZHANG Key Laboratory of Universal Wireless Communications Ministry of EducationBeijing University of Posts and Telecommunications Smart City College Beijing Union University

Network architecture design is critical for optimizing industrial networks. Network architectures can be classified into small-scale networks and large-scale networks based on scale. Graph theory is an efficient mathematical tool for network topology modeling. For small-scale networks, their structure often has regular topology. For large-scale ones, the current body of work mainly focuses on random characteristics of network nodes and edges. Recently, widely used models include random networks, small-world networks,and scale-free networks. In this study, starting from the scale of the network, network modeling methods based on graph theory as well as their industrial applications, are summarized and analyzed. Moreover, a novel network performance metric, called system entropy, is proposed. From the perspective of mathematical properties, an analysis of its non-negativity and concavity is performed. The advantage of system entropy is that it can cover the existing regular networks, random networks, small-world networks, and scale-free networks, and has strong generality. The simulation results reveal that this proposed metric can achieve the comparison of various industrial networks under different models.

关键词： industrial network small-scale network large-scale network graph theory system entropy

The CST bounce universe model——A parametric study

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Science China(Physics,Mechanics & Astronomy) 2019年第1期62卷 9-15页

作者： Yeuk-Kwan Edna Cheung xue Song ShuYi Li YunXuan Li Yiqing Zhu Department of Physics Nanjing University Institute of High Energy Physics China Academy of Sciences Department of Physics Princeton University Department of Physics Brown University California Institute of Technology ETH Zürich

A bounce universe model with a scale-invariant and stable spectrum of primordial density perturbations was constructed using a consistent truncation of the D-brane dynamics from Type IIB string theory. A coupling was introduced between the tachyon field and the adjoint Higgs field on the D3-branes to lock the tachyon at the top of its potential hill and to model the bounce process,which is known as the Coupled Scalar and Tachyon Bounce(CSTB) Universe. The CSTB model has been shown to be ghost free,and it fulfils the null energy condition; in addition, it can also solve the Big Bang cosmic singularity problem. In this paper we conduct an extensive follow-up study of the parameter space of the CSTB model. In particular we are interested in the parameter values that can produce a single bounce to arrive at a radiation-dominated universe. We further establish that the CSTB universe is a viable alternative to inflation, as it can naturally produce a sufficient number of e-foldings in the locked inflation epoch and in the post-bounce expansion to overcome the four fundamental limitations of the Big Bang cosmology, which are flatness, horizon,homogeneity and singularity, resulting in a universe of the current size.

关键词： bounce universe Big Bang singularity tachyon inflation flatness and horizon problems

Different structural origins for different sized surface pits observed on a-plane GaN film

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Science China(Technological Sciences) 2016年第1期59卷 156-161页

作者： GAO ZhiYuan LI JiangJiang xue XiaoWei CUI BiFeng XING YanHui ZOU DeShu Microelectronic School Beijing University of Technology

A correlation study between the observed surface morphology using high-resolution scanning electron microscopy(HRSEM) and the observed structural imperfections using transmission electron microscopy(TEM) has been conducted for a-plane Ga N. There are three different sized asymmetric surface pits: large pit of 500 nm–2 ?m in side length, medium pit of 50 nm in side length, and small pit with side lengths of less than 5 nm, which originate from incomplete island coalescence, screw dislocation, and partial dislocation(PD), respectively. Both screw dislocation and PD can produce pits on the free surface because they have a perpendicular line tension to the surface, which must remain in balance with the surface tension. The two types of dislocation lead to distinctive pit sizes because the PD has a smaller Burgers vector component along the dislocation line than the pure screw dislocation. A pit that is produced in the island-coalescing process is much larger than those caused by dislocations because island coalescence is a kinetic process that involves large-scale mass transportation, whereas the dislocation mediates the surface in the local area. These three types of surface pits sometimes interact with one another in space. The coalescence of the island determines the surface morphology at large scales, whereas the defects affect the details.

关键词： surface pits nonpolar Ga N screw dislocations partial dislocations Island coalescence

Transition towards higher penetration of renewables: an overview of interlinked technical, environmental and socio-economic challenges

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Journal of Modern Power Systems and Clean Energy 2019年第1期7卷 1-8页

作者： Xinyu CHEN Michael B.MCELROY qiuwei WU Yinbiao SHU Yusheng xue John A.Paulson School of Engineering and Applied Sciences Harvard University Department of Electrical Engineering Technical University of Denmark State Grid Corporation of China State Grid Electric Power Research Institute

Investment for renewables has been growing rapidly since the beginning of the new century, and the momentum is expected to sustain in order to mitigate the impact of anthropogenic climate *** towards higher renewable penetration in the power industry will not only confront technical challenges, but also face socio-economic *** connected between environment and energy systems are also tightened under elevated penetration of *** paper will provide an overview of some important challenges related to technical, environmental and socio-economic aspects at elevated renewable *** integrated analytical framework for interlinked technical, environmental and socio-economic systems will be presented at the end.

关键词： Wind power Solar power Integrated energy systems Missing money problem Low carbon policies

Xi UOS: an open-source ubiquitous operating system for industrial Internet of Things

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Science China(Information Sciences) 2022年第1期65卷 262-263页

作者： Donggang CAO Dongliang xue Zhiyi MA Hong MEI Advanced Institute of Information Technology Peking University Computer Science Department Peking University Computer Science Department Shanghai Jiao Tong University

On May 4, 2021, a Chinese research team with members from AIIT（PKU Advanced Institute of Information Technology）, PKU（Peking University）, and SJTU（Shanghai Jiao Tong University）, openly released the source code of Xi UOS, a UOS（ubiquitous operating system） [1] for the industrial Internet of Things（IIo T）, under the open-source license of Mulan PSL v2 on Trustie1)and Mulan OS2).

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