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Influence of carbon content on microstructure and mechanical properties of 1000 MPa deposited metal by gas metal arc welding

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journal of Iron and Steel Research International 2019年第5期26卷 512-518页

作者： Tong-bang An jin-shan Wei Lin Zhao ji-guo shan Zhi-ling Tian Central Iron & Steel Research Institute Beijing 100081 China Department of Mechanical Engineering Tsinghua University Beijing 100084 China

The effects of carbon content (0.078-0.100 wt.%) on the microstructure and properties of 1000 MPa grade deposited metal produced by gas metal arc welding have been investigated. Experimental results show that the microstructure of the deposited metal was mainly composed of martensite, bainite and retained austenite. With increasing carbon content, the proportion of martensite increased, and the amount of bainite was reduced. High carbon content is beneficial to strength, but harmful to impact toughness, and thus, carbon reductions lead to the increase in impact toughness. When the carbon content was 0.100 wt.%, the lowest Charpy absorbed energy of 47 j at — 40℃ for the deposited metal was achieved, the highest yield strength of 1038 MPa was attained, and the yield-to-tensile ratio was more than 0.88, while the highest Charpy absorbed energy of 55.7 j at — 40℃ and the lowest yield strength of 915 MPa were obtained when the deposited metal contains 0.078 wt.% C, and the yield-to-tensile ratio was less than 0.85. It is concluded that bainite fraction and fine effective grain size were the dominant factors to achieve good comprehensive mechanical properties (the required strength and an acceptable toughness) of deposited metals with various carbon contents.

关键词： 1000 MPa grade deposited metal Carbon content Microstructure Strength Gas metal arc welding Impact toughness

煤中惰质组及其古环境意义:来自AI和大数据分析的启示

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中国科学：地球科学 2024年第6期54卷 1806-1829页

作者：邵龙义周家民 Timothy P.jONES 华芳辉徐小涛闫志明侯海海王东东鲁静中国矿业大学(北京)煤炭精细勘探与智能开发全国重点实验室中国矿业大学(北京)地球科学与测绘工程学院北京100083 School of Earth and Environmental Sciences Cardiff UniversityCardiffCF103YEWalesEngland 中国煤炭地质总局勘查研究总院北京100039 潍坊学院土木与交通学院潍坊261061 辽宁工程技术大学矿业学院阜新123000 山东科技大学地球科学与工程学院青岛266590

惰质组是煤中常见且重要的显微组分组,作为古野火指示物在古环境研究中发挥着至关重要的作用,古野火在多种生态系统中扮演着不可替代的角色.通过惰质组来讨论古野火与古气候变化及古植物演化的研究逐年增多.丝质体和半丝质体的反射率可... 详细信息

惰质组是煤中常见且重要的显微组分组,作为古野火指示物在古环境研究中发挥着至关重要的作用,古野火在多种生态系统中扮演着不可替代的角色.通过惰质组来讨论古野火与古气候变化及古植物演化的研究逐年增多.丝质体和半丝质体的反射率可以用来估算古野火的燃烧温度及类型,进而判断不同类型野火的燃烧特征.惰质组的相对丰度可以重建大气氧含量.人工智能(AI)和科学数据库的在线搜索工具的快速发展,使得查找、收集、整理和分析从最老到最新的出版物,以及出版物中的全球惰质组数据成为可能.本文使用数据提取工具Deep Shovel收集分析从志留纪到新近纪的全球惰质组数据,然后应用Gplates、ArcGIS pro、Tableau等多个软件建立地质历史时期惰质组相对丰度的变化模型,该模型可以与其他因素如大气氧含量、植物进化及古气候变化等进行关联.惰质组在地质历史中的分布特征差异很大,二叠纪属于典型的“高惰质组含量-高大气氧含量”时期,新生代属于典型的“低惰质组含量-低大气氧含量”时期.本文提出惰质组特征与古环境因素之间的可能性正负反馈关系,揭示出惰质组在地质古环境演化研究中发挥着不可替代的作用.未来惰质组相关研究应该聚焦在有机岩石学和有机地球化学的深入结合,大数据驱动的惰质组时、空分布特征,古野火在不同气候背景下的地球系统中发挥的作用以及融合现代野火研究预测未来由于气候变化导致的野火发生的频率和强度.

关键词：惰质组古野火大气氧含量古气候古生态系统

基于模拟退火粒子群算法与小冲杆试验确定材料塑性性能的方法

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华东理工大学学报（自然科学版） 2024年第1期50卷 153-160页

作者：单应强钟继如王琼琦关凯书华东理工大学机械与动力工程学院承压系统与安全教育部重点实验室上海200237

为了能够准确合理地从小冲杆试验曲线中获取材料的塑性参数,提出了一种基于模拟退火粒子群算法和有限元模拟获得材料断后伸长率及断面收缩率的方法。首先通过小冲杆试验获取X65、X70管线钢的载荷-位移曲线;其次利用模拟退火粒子群算法... 详细信息

为了能够准确合理地从小冲杆试验曲线中获取材料的塑性参数,提出了一种基于模拟退火粒子群算法和有限元模拟获得材料断后伸长率及断面收缩率的方法。首先通过小冲杆试验获取X65、X70管线钢的载荷-位移曲线;其次利用模拟退火粒子群算法和有限元模拟相结合的方法,使得小冲杆模拟曲线逼近试验曲线,进而识别johnson-Cook(j-C)本构模型参数;最后将识别的参数用于模拟单轴拉伸试验,从而获取材料断后伸长率和断面收缩率。该方法所获得的两种管线钢的断后伸长率、断面收缩率与单轴拉伸试验结果的最大相对误差分别为23.58%、3.70%。

关键词：小冲杆试验模拟退火粒子群算法塑性性能 johnson-Cook模型有限元模拟

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Postcranial disparity of galeaspids and the evolution of swimming speeds in stem-gnathostomes

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National Science Review 2023年第7期10卷 81-90页

作者： Zhikun Gai Xianghong Lin Xianren shan Humberto G.Ferrón Philip C.j.Donoghue Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences Institute of Vertebrate Paleontology and Paleoanthropology Chinese Academy of Sciences University of Chinese Academy of Sciences Bristol Palaeobiology Group School of Earth Sciences University of Bristol Instituto Cavanilles de Biodiversidad i Biología Evolutiva Universitat de València

Galeaspids are extinct jawless relatives of living jawed vertebrates whose contribution to understanding the evolutionary assembly of the gnathostome bodyplan has been limited by absence of postcranial ***,we describe Foxaspis novemura *** ***.,based on complete articulated remains from a newly discovered Konservat-Lagerstatte in the Early Devonian(Pragian,～410 Ma) of Guangxi,South China.F,novemura had a broad,circular dorso-ventrally compressed headshield,slender trunk and strongly asymmetrical hypochordal tail fin comprised of nine ray-like scale-covered *** tail morphology contrasts with the symmetrical hypochordal tail fin of Tujiaaspis vividus,evidencing disparity in galeaspid postcranial *** of swimming speed reveals galeaspids as moderately fast swimmers,capable of achieving greater cruising swimming speeds than their more derived jawless and jawed *** analyses reject the hypothesis of a driven trend towards increasingly active food acquisition which has been invoked to characterize early vertebrate evolution.

关键词： Galeaspida jawed vertebrates evolution functional morphology phylogenetics modelling

Optimization of thermal processing parameters of Ti555211 alloy using processing maps based on Murty criterion

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Rare Metals 2016年第2期35卷 154-161页

作者： Zhen An jin-shan Li Yong Feng State Key Laboratory of Solidification Processing Northwestern Polytechnical University

Isothermal compression testing of Ti555211 titanium alloys was carried out at deformation temperatures from 750 to 950 °C in 50 °C intervals with a strain rate of0.001-1.000 s^（-1）. The high-temperature deformation behavior of the Ti555211 alloy was characterized by analysis of stress-strain behavior, kinetics and processing maps. A constitutive equation was formulated to describe the flow stress as a function of deformation temperature and strain rate, and the calculated apparent activation energies are found to be 454.50 and 207.52 k j mol^（-1）in the a b-phase and b-phase regions, respectively. A processing map based on the Murty instability criterion was developed at a strain of 0.7. The maps exhibit two domains of peak efficiency from 750 to 950 °C. A ＊60 % peak efficiency occurs at 800-850 °C/0.001-0.010 s^（-1）. The other peak efficiency of ＊60 % occurs at C950 °C/0.001-0.010 s^（-1）, which can be considered to be the optimum condition for high-temperature working of this ***, at strain rates of higher than 1.000 s^（-1）and deformation temperatures of 750 and 950 °C, clear process flow lines and bands of flow localization occur in the hightemperature deformation process, which should be avoided in Ti555211 alloy hot processing. The mechanism in stability domain and instability domain was also discussed.

关键词： Ti555211 titanium alloy High temperature Deformation behavior Processing maps

An R(x)-orthonormal theory for the vibration performance of a non-smooth symmetric composite beam with complex interface

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Acta Mechanica Sinica 2019年第1期35卷 228-241,I0007页

作者： Chein-shan Liu Bo-Tong Li College of Mechanics and Materials Hohai UniversityNanjing 210098China Center of Excellence for Ocean Engineering Department of Mechanical and Mechatronic EngineeringTaiwan Ocean UniversityKeelung 202-24China School of Mathematics and Physics University of Science and Technology BeijingBeijing 100083China

A composite beam is symmetric if both the material property and support are symmetric with respect to the middle point. In order to study the free vibration performance of the symmetric composite beams with different complex nonsmooth/discontinuous interfaces, we develop an R(x)-orthonormal theory, where R(x) is an integrable flexural rigidity function. The R(x)-orthonormal bases in the linear space of boundary functions are constructed, of which the second-order derivatives of the boundary functions are asked to be orthonormal with respect to the weight function R(x). When the vibration modes of the symmetric composite beam are expressed in terms of the R(x)-orthonormal bases we can derive an eigenvalue problem endowed with a special structure of the coefficient matrix A :=[aij ],aij= 0 if i + j is odd. Based on the special structure we can prove two new theorems, which indicate that the characteristic equation of A can be decomposed into the product of the characteristic equations of two sub-matrices with dimensions half lower. Hence, we can sequentially solve the natural frequencies in closed-form owing to the specialty of A. We use this powerful new theory to analyze the free vibration performance and the vibration modes of symmetric composite beams with three different interfaces.

关键词： Symmetric composite beams R(x)-orthogonality of second-order derivatives of boundary functions R(x)-orthonormal theory Non-smooth/discontinuous interface Sequentially closed-from natural frequencies

Computation of Five-Dimensional Grain Boundary Energy

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Acta Metallurgica Sinica(English Letters) 2015年第5期28卷 634-640页

作者： Yong-Kun Luo Rong-shan Qin Department of Materials Imperial College London

Abstract A broken-bond type computational method has been developed for the calculation of the five-dimensional grain boundary energy. The model allows quick quantification of the unrelaxed five-dimensionally specified grain boundary energy in arbitrary orientations. It has been validated on some face-centred cubic metals. The stereo projections of grain boundary energy of ∑3,∑5,∑7, ∑9, ∑11, ∑17b and ∑31a have been studied. The results of Ni closely resemble experimentally determined grain boundary energy distribution figures, suggesting that the overall anisotropy of grain boundary energy can be reasonably approximated by the present simple model. Owing to the overlooking of relaxation matter, the absolute values of energy calculated in present model are found to be higher than molecular dynamic-based results by a consistent magnitude, which is 1 j/m2 for Ni. The coverage of present method forms a bridge between atomistic and meso-scale simulations regarding polycrystalline microstructure.

关键词： Boundaries Grain boundary energy Grain boundary structure

Short-time Lv transform and its application for non-linear FM signal detection

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journal of Systems Engineering and Electronics 2015年第6期26卷 1159-1168页

作者： shan Luo Xiumei Li Guoan Bi School of Aeronautics and Astronautics University of Electronic Science and Technology of China School of Information Science and Engineering Hangzhou Normal University School of Electrical and Electronic Engineering Nanyang Technological University

A new time-frequency transform, known as short-time Lv transform （STLVT）, is proposed by applying the inverse Lv distribution to process consecutive segments of long data sequence. Compared with other time-frequency representations, the STLVT is able to achieve better energy concentration in the time-frequency domain for signals containing multiple linear and/or non-linear frequency modulated components. The merits of the STLVT are demonstrated in terms of the effects of window length and overlap length between adjacent segments on signal energy concentration in the time-frequency domain, and the required computational complexity. An application on the spectrum sensing for cognitive ratio （CR） by using a joint use of the STLVT and Hough transform （HT） is proposed and simulated.

关键词： Lv distribution time-frequency transform frequencymodulated signal spectrum sensing.

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弥勒异种等级烤烟陈化致香成分分析研究

山西化工 2024年第6期44卷 53-55页

作者：单妍魏云林昆明医科大学海源学院云南昆明650106 昆明理工大学生命科学与技术学院云南昆明650500

为分析烤烟品种和等级对自然陈化后烟叶品质的影响,以云南省红河州弥勒地区的两个不同品种和等级的烤烟为原料,于该地经自然陈化后,重点测定和分析了陈化前后不同烤烟致香成分的变化情况。研究结果表明:不同品种不同等级烟叶致香成分总... 详细信息

为分析烤烟品种和等级对自然陈化后烟叶品质的影响,以云南省红河州弥勒地区的两个不同品种和等级的烤烟为原料,于该地经自然陈化后,重点测定和分析了陈化前后不同烤烟致香成分的变化情况。研究结果表明:不同品种不同等级烟叶致香成分总量在陈化过程中均处于积累状态,且增长迅速,在陈化一年后,致香物质的总量增加了一倍,使得烟叶的内在品质得到显著提高。针对K326来说其致香成分在前期增长缓慢,后期则增长迅速;而红大(HD)烤烟则在前期致香成分增长迅速,后期反而变缓。由此可见,不同品种烤烟在陈化过程中其致香物质的总量增长趋势一致;而就致香物质增加的百分率看,K326-51和HD-51的增长率高于K326-41和HD-41。本研究初步揭示了自然陈化后不同品种等级烤烟致香成分的变化规律,可为弥勒仓储筛选最适宜的陈化烟叶品种,也可为弥勒卷烟仓储企业对烟叶的合理陈化及利用提供参考。

关键词：烤烟陈化品种等级致香成分