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Experimental and numerical study on plasma nitriding of AISI P20 mold steel

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International Journal of Minerals,Metallurgy and Materials 2016年第9期23卷 1065-1075页

作者： N.Nayebpashaee h.Vafaeenezh.d sh.Kh.irandish M.Soltanieh Materials Processing Simulation Laboratory(MPS-LAB) School of Materials and Metallurgical EngineeringIran University of Science and Technology(IUST) Sch.ol of Materials and Metallurgical Engineering Iran University of Science and Technology(IUST)

In th.s study, plasma nitriding was used to fabricate a h.rd protective layer on AISI P20 steel, at th.ee process temperatures（450℃, 500℃, and 550℃） and over a range of time periods（2.5, 5, 7.5, and 10 h., and at a fixed gas N2：h. ratio of 75vol%：25vol%. Th. morph.logy of samples was studied using optical microscopy and scanning electron microscopy, and th. formed ph.se of each.sample was determined by X-ray diffraction. Th. elemental depth.profile was measured by energy dispersive X-ray spectroscopy, wavelength.dispersive spectroscopy, and glow dispersive spectroscopy. Th. h.rdness profile of th. samples was identified, and th. microh.rdness profile from th. surface to th. sample center was recorded. Th. results show th.t ε-nitride is th. dominant species after carrying out plasma nitriding in all strategies and th.t th. plasma nitriding process improves th. h.rdness up to more th.n th.ee times. It is found th.t as th. time and temperature of th. process increase, th. h.rdness and h.rdness depth.of th. diffusion zone considerably increase. Furth.rmore, artificial neural networks were used to predict th. effects of operational parameters on th. mech.nical properties of plastic mold steel. Th. plasma temperature, running time of imposition, and target distance to th. sample surface were all used as network inputs; Vickers h.rdness measurements were given as th. output of th. model. Th. model accurately reproduced th. experimental outcomes under different operational conditions; th.refore, it can be used in th. effective simulation of th. plasma nitriding process in AISI P20 steel.

关键词： tool steel plasma nitriding sputtering neural networks

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产业链韧性测度方法研究进展

经济学动态 2024年第4期 144-160页

作者：肖兴志王振宇李少林东北财经大学产业组织与企业组织研究中心 116025

产业链韧性测度是识别“断链”风险和维护产业链安全稳定的现实抓手,成为新时代应对、把握和引领大变局亟待解决的热点问题。本文在分析产业链韧性测度现实需求的基础上,从产业链韧性测度的理论基础、方法类型、应用步骤三个方面就经典... 详细信息

产业链韧性测度是识别“断链”风险和维护产业链安全稳定的现实抓手,成为新时代应对、把握和引领大变局亟待解决的热点问题。本文在分析产业链韧性测度现实需求的基础上,从产业链韧性测度的理论基础、方法类型、应用步骤三个方面就经典文献进行述评。首先,围绕恢复、抵抗、适应与变革四大能力追溯概念界定、内涵特征和学科交叉的理论起源;其次,系统梳理了以核心变量法、综合评价法及投入产出法为代表的产业链韧性评价方法,剖析了各自优点与相对不足;最后,全面厘清了“冲击识别—结构分析—韧性评价”框架下的韧性测度理论与方法应用。本文认为,产业链韧性测度方法的选取及应用须高度重视学科交叉的应用场景,廓清理论模型的适用条件,为测度和增强产业链韧性提供多样化、稳健性的方法支撑。

关键词：产业链韧性经济韧性测度方法

Influences of substrate temperature on microstructure and corrosion beh.vior of APS Ni_(50)Ti_(25)Al_(25) inter-metallic coating

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Ch.nese Ph.sics B 2018年第2期27卷 607-612页

作者： sh Kh.ndanjou M Gh.ranneviss sh Saviz M Reza Afshar Plasma Ph.sics Research.Center Science and Research Branch Islamic Azad University Department of Materials Engineering Science and Research Branch Islamic Azad University

In th. present investigation, Ni_（50）Ti_（25）Al_（25）（at.%） mech.nically alloyed powder is deposited on carbon steel *** th. coating process, th. substrate is h.ated to temperature ranging from room temperature to 400℃. Th. microstructure, porosity, microh.rdness, adh.sion strength. and corrosion beh.vior of th. coating are investigated at different substrate temperatures. Results show th.t coating porosity is lower on h.gh.temperature surface. Microh.rdness and adh.sion strength.of th. deposition layer on th. substrate with.ut preh.ating h.ve lower values th.n with.preh.ating. Th. polarization test result shows th.t corrosion performance of th. coating is dependent on micro cracks and porosities and th. increasing of substrate temperature can improve th. quality of coating and corrosion performance.

关键词： Ni50Ti25Al25 coating air plasma spray planetary ball milling inter-metallic compounds corrosion resistance

Radiation of Ultra Low Frequency Electromagnetic Waves from Atmosph.re under th. Influence of Strong shock Waves

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Ch.nese Ph.sics Letters 2015年第3期32卷 39-41页

作者： A. R. Aramyan S. A. Aramyan S. G. Bilen L. sh. Grigoryan h. F. Kh.ch.tryan Institute of Applied Problems of Ph.sics National Academy of Sciences of Armenia Yerevan 0014 Republic of Armenia International Scientific and Educational Center National Academy of Sciences of Armenia Yerevan 0019 Republic of Armenia Pennsylvania State University University Park PA USA

We present preliminary results from th. experimental investigation of th. response of th. atmosph.re due to th. impact of powerful shock waves. Th. response is evidenced as ultra low frequency electromagnetic wave radiation at frequency of 2-5 kh. and in duration of 3 7s. We h.poth.size th.t th.s radiation appears due to th. following process： th. shock wave ionizes th. neutral particles in th. air and th.se ch.rged and neutral particles continue th.ir vertical motion, wh.ch.forms in th. trail of th. shock wave. Such.motion can cause th. cyclotron-like radiation measured.

关键词： Radiation of Ultra Low Frequency Electromagnetic Waves from Atmosph.re under th. Influence of Strong shock Waves

A Study on th. Wear Beh.viour of Dual Ph.se Steels

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Journal of Materials Science & Tech.ology 2007年第1期23卷 107-110页

作者： V.Abouei h.Sagh.fian sh.Kh.irandish Kh.Ranjbar Department of Metallurgy and Materials Engineering Iran University of Science and TechnologyIran shah.d Ch.mran University Iran

Dual ph.se （DP） steels containing four different amounts of martensite ranging from 43 vol. pct to 81 vol. pct h.ve been developed from 0.2 wt pct carbon steel by intercritical h.at treatment at a fixed temperature of 780℃ with.varying h.lding times followed by water quench.ng. Dry sliding wear tests h.ve been conducted on DP steels using a pin- on-disk mach.ne under different normal loads of 61.3, 68.5, 75.7 and 82.6 N and at a constant sliding speed of 1.20 m/s. At th.se loads, th. mech.nism of wear is primarily delamination, wh.ch.h.s been confirmed by SEM micrograph. of subsurface and wear debris of samples. Wear properties h.ve been found to improve with.th. increase in martensite volume fraction in dual ph.se steels.

关键词： Wear Dual ph.se steel Microstructure

Prediction of yttrium, lanth.num, cerium, and neodymium leach.ng recovery from apatite concentrate using artificial neural networks

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Journal of University of Science and Tech.ology Beijing 2008年第4期15卷 367-374页

作者： E. Jorjani A.h. Bagh.rieh.sh. Mesrogh.i S. Ch.h.eh.Ch.lgani Department of Mining Engineering Research and Science Campus Islamic Azad University Poonak Hesarak Tehran Iran

Th. assay and recovery of rare earth.elements （REEs） in th. leach.ng process is being determined using expensive analytical meth.ds： inductively coupled plasma atomic emission spectroscopy （ICP-AES） and inductively coupled plasma mass spectroscopy （ICP-MS）. A neural network model to predict th. effects of operational variables on th. lanth.num, cerium, yttrium, and neodymium recovery in th. leach.ng of apatite concentrate is presented in th.s article. Th. effects of leach.ng time （10 to 40 min）, pulp densities （30% to 50%）, acid concentrations （20% to 60%）, and agitation rates （100 to 200 r/min）, were investigated and optimized on th. recovery of REEs in th. laboratory at a leach.ng temperature of 60℃. Th. obtained data in th. laboratory optimization process were used for training and testing th. neural network. Th. feed-forward artificial neural network with.a 4-5-5-1 arrangement was capable of estimating th. leach.ng recovery of REEs. Th. neural network predicted values were in good agreement with.th. experimental results. Th. correlations of R=l in training stages, and R=0.971, 0.952, 0.985, and 0.98 in testing stages were a result of Ce, Nd, La, and Y recovery prediction respectively, and th.se values were usually acceptable. It was shown th.t th. proposed neural network model accurately reproduced all th. effects of th. operation variables, and could be used in th. simulation of a leach.ng plant for REEs.

关键词： apatite neural networks rare earth.elements leach.ng recovery

Ph.toch.mistry of ph.noth.azine in benzene and cycloh.xane

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Ch.nese Science Bulletin 1997年第12期42卷 998-1000页

作者： Wang, sh Ch.n, DW Gou, JX Wang, h Institute of Ch.mistry Chinese Academy of Sciences Beijing China

IN th. last few years ph.noth.azine(PTh.and its derivatives h.ve captured much.attention inth. fields of medicines,biology,and microelectronic materials due to th.ir ability to ef-ficiently ph.tosensitize acid production in th. presence of vicinal dibromides and h.nce toch.nge th. solubilization of polymer *** ph.toph.sical and ph.toch.mical properties re-lated to th. processes h.ve been *** Barra et *** th.t th. triplet

关键词： ph.toch.mistry ESR nitroxyl radical cation radical.

Solving two-dimensional Volterra-Fredh.lm integral equations of th. second kind by using Bernstein polynomials

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Applied Math.matics(A Journal of Ch.nese Universities) 2017年第1期32卷 68-78页

作者： M.sh.Dah.gh.n sh.Eskandari Department of Math.matics Shahrekord University Shahrekord Iran

In th.s paper, we present a numerical meth.d for solving two-dimensional VolterraFredh.lm integral equations of th. second kind（2DV-FK2）. Our meth.d is based on approximating unknown function with.Bernstein polynomials. We obtain an error bound for th.s meth.d and employ th. meth.d on some numerical tests to show th. efficiency of th. meth.d.

关键词： Volterra approximating approximate variational proof iterative uniformly exact wavelet inequality

Synth.sis and ch.racterization of boron-doped NiO th.n films pro-duced by spray pyrolysis

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International Journal of Minerals,Metallurgy and Materials 2013年第11期20卷 1097-1101页

作者： U.Alver h.Yayka sh S.Kerli A.Tanr verdi Department of Ph.sics Kahramanmaras Sutcu Imam University Department of Electrical and Electronics Engineering International University of Sarajevo Research.and Development Center for University-Industry and Public Relations (USKIM)

Boron-doped NiO th.n films were prepared on glass substrates at 400℃ by airbrush spraying meth.d using a solution of nickel nitrate h.xah.drate. Th.ir ph.sical properties were investigated as a function of dopant concentration. From X-ray diffraction patterns, it is observed th.t th. films h.ve cubic structure with.lattice parameters varying with.boron concentration. Th. morph.logies of th. films were examined by using scanning electron microscopy, and th. grain sizes were measured to be around 30-50 nm. Optical measurements show th.t th. band gap energies of th. films first decrease th.n increase with.increasing boron concentration. Th. resistivities of th. films were determined by four point probe meth.d, and th. ch.nges in resistivity with.boron concentration were investigated.

关键词： nickel oxide th.n films spray pyrolysis boron resistivity