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Work Hardening Behavior of 1020 Steel During Cold-Beating Simulation

Chinese Journal of Mechanical Engineering 2017年第2期30卷 321-331页

作者： Fengkui CUI Yuanfei LING Jinxue XUE jia liu Yuhui liu Yan LI School of Mechatronics Engineering Henan University ofScience and TechnologyLuoyang 471003China Collaborative Innovation Center of Machinery Equipment Advanced Manufacturing of Henan Province Henan University of Science and TechnologyLuoyang 471003China School of Mechanical and Precision Instrument Engineering Xi'an University of Technology Xi'an 710048China

The present research of cold-beating formation mainly focused on roller design and manufacture, kinematics, constitutive relation, metal flow law, thermo-mechanical coupling, surface micro-topography and microstructure evolution. However, the research on surface quality and performance of workpieces in the process of cold-beating is rare. Cold-beating simulation experiment of 1020 steel is conducted at room temperature and strain rates ranging from 2000 to 4000 s^-1 base on the law of plastic forming. According to the experimental data, the model of strain hardening of 1020 steel is established, Scanning Electron Microscopy（SEM） is conducted, the mechanism of the work hardening of 1020 steel is clarified by analyzing microstructure variation of 1020 steel. It is found that the strain rate hardening effect of 1020 steel is stronger than the softening effect induced by increasing temperatures, the process of simulation cold-beating cause the grain shape of 1020 steel significant change and microstructure elongate significantly to form a fibrous tis- sue parallel to the direction of deformation, the higher strain rate, the more obvious grain refinement and the more hardening effect. Additionally, the change law of the work hardening rate is investigated, the relationship between dislocation density and strain, the relationship between work hardening rate and dislocation density is obtained. Results show that the change trend of the work hardening rate of 1020 steel is divided into two stages, the work hardening rate decreases dramatically in the first stage and slowly decreases in the second stage, finally tending toward zero. Dislocation density increases with increasing strain and strain rate, work hardening rate decreases with increasing dislocation density. The research results provide the basis for solving the problem of improving the surface quality and performance of workpieces under cold-beating formation of 1020 steel.

关键词： 1020 steel Cold·beating Work hardening Grain Dislocation density

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Structure and Luminescent Properties of Sm^(3+) Doped SrO-MgO-SiO_2 Glass Ceramics

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Journal of Wuhan University of Technology(Materials Science) 2015年第2期30卷 282-287页

作者：章璐娴何峰 XIE Junlin liu jia School of Materials Science and Engineering Wuhan University of Technology State Key Laboratory of Silicate Materials for Architectures Wuhan University of Technology

A new type of samarium ion activated luminescent glass ceramics with main crystal phase of melilite was prepared. The effect of heat-treatment temperature on the structure of glass ceramics was investigated by X-ray diffraction analysis（XRD）, scanning electron microscope（SEM） and fluorescence spectrometer. In the Sm^3＋ doped SrO-MgO-SiO2 glass ceramic, its excitation spectra are in the wavelength range of 350-500 nm, and its excitation peaks are at 360 nm, 374 nm, 404 nm, 417 nm, and 475 nm with the host excitation peak of 404 nm, showing a strong orange-red luminescence when using 404 nm violet to excite it, and its emission peaks are at 564 nm, 600 nm and 648 nm with the host emission peak at 600 nm. The increase in the heat-treatment temperature has no infl uence on the position of the fl uorescent spectra. However, with the increase of heat-treatment temperature, the intensity of fl uorescence spectrum shows an increasing tendency. The increase in the concentration of Sm3＋ also improves the intensity of the fl uorescent spectra. In the experimental concentration range（0.05mol%-0.30mol%）, a special concentration quenching phenomenon happens.

关键词： glass ceramics rare earth luminescence

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Systematic differences in position and proper-motion between the PPMX and UCAC3 catalogs

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Research in Astronomy and Astrophysics 2011年第9期11卷 1074-1084页

作者： jia-Cheng liu Zi Zhu Bo Hu Department of Astronomy Nanjing University Nanjing 210093 China Key Laboratory of Modern Astronomy and Astrophysics （Nanjing University） Ministry of Education Nanjing 210093 China Purple Mountain Observatory Chinese Academy of Sciences Nanjing 210008 China Graduate University of Chinese Academy of Sciences Beijing 100049 China

Considered to be extensions of the Hipparcos reference system, PPMX and UCAC3 are two of the most important astrometric catalogs released in current years. Extensive analyses of these two large catalogs have been made in order to determine the local and overall systematic biases. The regional and magnitude dependent differences in stellar position and proper motion are comparable to random errors and are even larger in the northern hemisphere. The global orientation bias vector ε between the two systems is also significant （up to 17 mas）, which shows the overall differences of the PPMX and UCAC3 catalogs and their reference systems. On the other hand, the term for the global rotation vector a; is small （tenths of mas per year）： it is reasonable to believe that the PPMX and UCAC3 reference frames do not rotate with respect to each other. Because of plate dependent and field-to-field errors in the UCAC3 catalog, we suggest that positions and proper motions of UCAC3 stars in the northern hemisphere （δ 〉 -20°） should be used with caution.

关键词： astrometry -- catalogs -- reference systems

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Majorana fermions in semiconducting nanowire and Fulde–Ferrell superconductor hybrid structures

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Frontiers of physics 2019年第1期14卷 147-154页

作者： jia liu Chun Fai Chan Ming Gong Guangdong Provincial Key Laboratory of Quantum Engineering and Quantum Materials and School of Physics and Telecommunication Engineering South China Normal University Guangzhou 510006 China Department of Physics and Center of Coherence The Chinese University of Hong Kong Shatin N. T. Hong Kong China Key Laboratory of Quantum Information University of Science and Technology of China Hefei 230026 China Guangdong Provincial Key Laboratory of Quantum Engineering and Quantum Materials and School of Physics and Telecommunication Engineering South China Normal University Guangzhou 510006 China

The novel idea that spin-orbit coupling (SOC) and an s-wave pairing system can lead to induced pwave pairing with a strong magnetic limit, has stimulated widespread interest in searching for Majorana fermions (MFs) in semiconductor-superconductor hybrid structures. However, despite major advances in the semiconductor nanotechnology, this system has several inherent limitations that prohibit the realization and identification of MFs. We overcome these limitations by replacing the s-wave superconductor with the type-II Fulde-Ferrell (FF) superconductor, in which the center-of-mass momentum of the Cooper pair renormalizes the in-plane Zeeman field and chemical potential. As a result, MFs can be realized in semiconductor nanowires with small values of the Landé g-factor and high carrier densities. The SOC strength directly influences the topological boundary;thus, the topological phase transition and associated MFs can be engineered by an external electric field. Theoretically, almost all semiconductor nanowires can be used to realize MFs by using the FF superconductor. However, we find that InP nanowire is more suitable for the realization of MFs compared to InAs and InSb nanowires. Thus, this new scheme can take full advantage of the semiconductor nanotechnology for the realization of MFs in semiconductor-superconductor hybrid structures.

关键词： Majorana fermion topological transition Pfaffian FF-superconductor hybrid structure

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Comparative study of gel-based separated arcdischarge, HiPCO, and CoMoCAT carbon nanotubes for macroelectronic applications

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Nano Research 2013年第12期6卷 906-920页

作者： jialu Zhang Hui Gui Bilu liu jia liu Chongwu Zhou Department of Electrical Engineering University of Southern California Los Angeles California 90089 USA Department of Material Science University of Southern Califomia Los Angeles California 90089 USA Department of Chemistry University of Southern California Los Angeles California 90089 USA

Due to their excellent electrical properties and compatibility with room-temperature deposition/printing processing, high-purity single-walled semiconducting carbon nanotubes hold great potential for macroelectronic applications such as in thin-film transistors and display back-panel electronics. However, the relative advantages and disadvantages of various nanotubes for macroelectronics remains an open issue, despite the great significance. Here in this paper, we report a com- parative and systematic study of three kinds of mainstream carbon nanotubes （arc-discharge, HiPCO, CoMoCAT） separated using low-cost gel-based column chromatography for thin-film transistor applications, and high performance transistors--which satisfy the requirements for transistors used in active matrix organic light-emitting diode displays--have been achieved. We observe a trade-off between transistor mobility and on/off ratio depending on the nanotube diameter. While arc-discharge nanotubes with larger diameters lead to high device mobility, HiPCO and CoMoCAT nanotubes with smaller diameters can provide high on/off ratios （〉 106） for transistors with comparable dimensions. Furthermore, we have also compared gel-based separated nanotubes with nanotubes separated using the density gradient ultracentrifuge （DGU） method, and find that gel-separated nanotubes can offer purity and thin-film transistor performance as good as DGU-separated nanotubes. Our approach can serve as the critical foundation for future carbon nanotube-based thin-film macroelectronics.

关键词： separated carbonnanotubes thin-film transistors gel-based columnchromatography purity of semiconductingnanotubes diameter-dependence

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Microstructure Characterization and Mechanical Properties of FGH 95 Turbine Blade Retainers

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Journal of Iron and Steel Research International 2010年第9期17卷 73-78页

作者： TAO Yu jia jian liu jian-tao Central Iron and Steel Research Institute Beijing 100081 China

FGH 95 is a powder metallurgy （P/M） processed superalloy, which was developed in the 1980s in China. One of the applications of FGH 95 was high pressure turbine blade retainers. The manufacturing processes used to produce FGH 95 blade retainers consisted of atomization by plasma rotating electrode process （PREP）, hot isostatic pressing （HIP） at super-solvus temperature and a sub-solvus solution heat treatment. The material had an equiaxed grain structure （ASTM 6.5-7.5）. The γ precipitates in as-HIP FGH 95 showed a tri-model distribution. Carbides in the alloy were MC type and precipitated at grain boundaries. The prior particle boundaries （PPB） in the material originated mainly from γ＇ phase. Statistics of the mechanical properties data from batch production of the FGH 95 blade retainers were investigated. The as-HIP FGH 95 blade retainers showed high strength at room temperature and 650 ℃, excellent creep resistance and outstanding stress rupture strength at 650 ℃.

关键词： FGH95 as-HiP P/M superalloy blade retainer microstructure mechanical property

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Lignin derived porous carbon with favorable mesoporous contributions for highly efficient ionic liquid-based supercapacitors

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Chinese Chemical Letters 2023年第10期34卷 293-297页

作者： jia liu Xiu-Wen Mei Feng Peng Beijing Key Laboratory of Lignocellulosic Chemistry MOE Engineering Research Center of Forestry Biomass Materials and BioenergyBeijing Forestry UniversityBeijing 100083China

Lignin and its derivatives hold great potential in developing high performance porous carbon materials for supercapacitors due to the versatile features of high carbon content, abundant multifunctional groups,low cost, and environmental benefits. Unfortunately, their derived porous carbon generally has the features of unfavorable microporous-dominated morphologies and low specific surface area(SSA) attributed from the highly-branched structure of lignin, which are hardly suitable for the supercapacitors with ionic liquid(IL) electrolyte, leading to poor energy density and rate capability. Herein, porous carbon materials with desirable mesoporous contributions from sodium lignosulphonate are designed via a facile template method. Such rich mesoporisity carbon materials not only possess with three-dimensional interconnected network, large SSA, as well as favorable pore size distribution for accelerated ion and electron mass transfer, but also feature low heteroatom content for high electrochemical stability. Consequently, the optimal electrode exhibits a high capacitance of 166 F/g at 0.5 A/g, superior rate performance(59 Wh/kg at 59 kW/kg), as well as impressive cycle life with good capacitance retention of 93.1% in EMIBF4 electrolytes. The present work opens a new avenue to design porous carbon materials with high mesopore properties from lignin for effective compatibility with IL electrolyte in high-performance supercapacitors.

关键词： Lignin Porous carbon Favorable mesoporous contributions Low heteroatom content Supercapacitors

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Crystal Structure and Biological Activities of (R)-N′-[2-(4-Methoxy-6-chloro)-pyrimidinyl]-N-[3-methyl-2-(4-chlorophenyl)butyryl]-urea

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Chinese Journal of Structural Chemistry 2006年第8期25卷 903-908页

作者： LI Jing-Zhi XUE Si-jia liu Guo-Hua Department of Chemistry College of Life and Environmental Science Shanghai Normal University Shanghai 200234 China

The title compound （R）-N′-[2-（4-methoxy-6-chloro）-pyrimidyl]-N-[3-methyl-2-（4- chlorophenyl）butyryl]-urea has been synthesized, and its crystal structure and biological behaviors were studied. Crystallographic data： C17H18C12N4O3, Mr = 397.25, monoclinic, space group P21/c, a = 12.331（2）, b = 14.025（3）, c = 23.085（5） A, β = 99.607（4）°, Z = 8, V = 3936.2（13） A3, Dc = 1.341 g/cm^3, F（000） = 1648, R = 0.0718, wR = 0.1585 and/t（MoKα） = 0.353 mm^-1. The preliminary biological tests showed that the title compound has definite insecticidal and fungicidal activities.

关键词： crystal structure biological activity (R)-3-methyl-2-(4-chlorophenyl)butyric acid 2-amino-6-chloro-4-methoxy-pyrimidine

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Impact of ENSO on MJO Pattern Evolution over the Maritime Continent

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Journal of Meteorological Research 2020年第6期34卷 1151-1166页

作者： jia liu Yuqin DA Tim LI Feng HU Key Laboratory of Meteorological Disaster Ministry of Education(KLME)/Joint International Research Laboratory of Climate and Environmental Change(ILCEC)/Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters(CIC-FEMD)Nanjing University of Information Science&TechnologyNanjing 210044China International Pacific Research Center and Department of Atmospheric Sciences School of Ocean and Earth Science and TechnologyUniversity of HawaiiHonoluluHI 96822USA

The modulation of Madden–Julian oscillation(MJO)pattern evolution over the Maritime Continent(MC)by El Nino–Southern Oscillation(ENSO)was investigated through a combined observational and modeling *** convective branches shifted south of the equator over the MC during eastern Pacific(EP)El Nino winters,while it became relatively symmetric about the equator during La Ni?a *** impact of central Pacific(CP)El Ninos to MJO pattern,on the other hand,is not statistically *** cause of the distinctive MJO pattern evolutions is likely attributed to the ENSO-induced changes of the background moisture and vertical shear over the *** numerical experiments with a 2.5-layer model were carried out,and the result revealed that the background moisture change played a dominant *** observational diagnosis of column-integrated moist static energy(MSE)budgets was further *** result indicated that the MJO pattern difference was attributed to the MSE tendency asymmetry in front of MJO convection between EP El Nino and La Ni?a,caused by the advection of the mean MSE by anomalous meridional *** difference in the MJO-scale anomalous meridional wind was ultimately controlled by the change of the background meridional moisture gradient associated with EP El Nino and La Ni?a.

关键词： Madden-Julian oscillation(MJO) El Nino-Southern Oscillation(ENSO) Maritime Continent(MC) moist static energy(MSE)budget

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Inflammatory myofibroblastic tumor of the pancreatic neck misdiagnosed as neuroendocrine tumor:A case report

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World Journal of Gastroenterology 2023年第20期29卷 3216-3221页

作者： jia-Bei liu Qian-Biao Gu Peng liu Department of Radiology The First Affiliated Hospital of Hunan Normal UniversityHunan Provincial People’s HospitalChangsha 410005Hunan ProvinceChina Department of Radiology The First Affiliated Hospital of Hunan Normal University(Hunan Provincial People’s Hospital)Changsha 410005Hunan ProvinceChina

BACKGROUND Inflammatory myofibroblastic tumor(IMT)is a relatively rare *** global incidence of IMT is less than 1%.There is no specific clinical *** usually occurs in the lungs,but the pancreas is not the predilection *** SUMMARY We present a case of a male patient,51 years old,who was diagnosed with a pancreatic neck small mass on ultrasound one year ago during a physical *** he had no clinical symptoms and the mass was relatively small,he did not undergo ***,the mass was found to be larger on review,and he was referred to our *** the primal clinical diagnosis was pancreatic neuroendocrine tumor,the patient underwent surgical ***,the case was confirmed as pancreatic IMT by postoperative *** Pancreatic IMT is relatively rare and easily *** can better understand and correctly diagnose this disease by this case report.

关键词： Inflammatory myofibroblastic tumor Diagnosis Imaging Pancreas Case report

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