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Availability Analysis of a Repairable Series-Parallel System with Redundant Dependency

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Journal of Systems Science & Complexity 2020年第2期33卷 446-460页

作者： HU Linmin YUE Dequan MA Zhanyou School of Science Yanshan UniversityQinhuangdao 066004China School of Economics and Management of Science Yanshan UniversityQinhuangdao 066004China

This paper investigates the steady-state availability of a repairable series-parallel system with redundant *** different types of components and repairmen are taken into account,the failure rate of the operating component varies as the number of other failed components and the repair rate of the failed component is constant in each parallel redundant *** quantify the redundant dependency,a modified failure dependence function is introduced to determine the failure rate of the components in each *** theory and matrix analysis method are used to get the steady-state probability vector of each subsystem and the steady-state availability of the entire system.A numerical example is presented to illustrate the obtained results and to analyze the effect of redundant dependency class on the system availability.

关键词： Availability probability redundant dependency repairable system series-parallel

Oil Pocket's Bearing Capacity Analysis of Liquid Hydrostatic Worktable in Gantry Moving Milling Center

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Chinese Journal of Mechanical Engineering 2014年第5期27卷 1008-1017页

作者： ZHAO Jianhua LIANG Yingna GAO Dianrong Hebei Provincial Key Laboratory of Heavy Machinery Fluid Power Transmission and Control Yanshan University Liren College Yanshan University

Durning the design process of hydrostatic rotary worktable,the processing and assembly tolerance,（the offset of worktable and the gap of the oil film’s thickness）is *** it will cause that the real bearing of oil pocket deviates from the initial design value,and then the performance of rotary worktable will be reduced *** to now,no effort is found toward the research of influence of the processing and assembly tolerance on the performance of the rotary *** the hydrostatic oil film is assumed as the elastomer in this paper,and then the bearing capacity of the oil pocket is studied with and without the mass offset of the worktable by taking an expression between the bearing capacity and the oil film’s thickness of the oil pocket as the deform compatibility *** influence of the processing tolerance of the oil sealing belt’s gap on the bearing capacity of the oil pocket is *** the light of the liquid hydrostatic worktable of Gantry Moving Milling Center using on the scene,the oil pocket’s pressure of the worktable is tested using Rotary Worktable Test System under the circumstance of the mass offset of the worktable and the gap tolerance of the oil sealing belt,and then the equivalent offset of worktable,the average pressure of the oil pocket and the actual thickness of the oil film are analyzed *** test results show that the bearing capacity component of the oil pocket caused by G is consistent,and the component caused by M is relative to the position of the oil *** the oil sealing belt’s gap is larger than the theoretical value,the bearing capacity of the oil pocket is smaller than the others;whereas the bearing capacity of the oil pocket is larger than the *** maximum and minimum equivalent offsets are 0.256 4 mm and 0.047 5 mm,respectively,and the average oil pocket pressure varies from 0.345 MPa to 0.460 MPa,the maximum and minimum value of the actual oil film thickness are 109.976？m（No.7 oil

关键词： Gantry Moving Milling Center bearing capacity processing and assembly tolerance mass offset

Enhanced electrochemical properties of LaFeO_3 with Ni modification for MH–Ni batteries

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International Journal of Minerals,Metallurgy and Materials 2018年第10期25卷 1201-1207页

作者： Zhen-tao Dong Yuan Li Kai-liang Ren Shu-qin Yang Yu-meng Zhao Yong-jie Yuan Lu Zhang Shu-min Han State Key Laboratory of Metastable Materials Science and Technology Yanshan University College of Environmental and Chemical Engineering Yanshan University

In this work,we synthesized LaFeO_3–xwt%Ni(x=0,5,10,15)composites via a solid-state reaction method by adding Ni to the reactants,La_2O_3 and Fe_2O_***-emission scanning electron microscopy(FE-SEM)and energy-dispersive X-ray spectroscopy(EDS)results revealed that Ni powders evenly dispersed among the LaFeO_3 particles and apparently reduced their aggregation,which imparted the composites with a loose ***,the Ni formed a conductive network,thus improving the conductivity of the *** maximum discharge capacity of the LaFeO_3 electrodes remarkably increased from 266.8 mAh·g^(–1)(x=0)to 339.7 mAh·g^(–1)(x=10).In particular,the high-rate dischargeability of the LaFeO_3–10wt%Ni electrode at a discharge current density of 1500 mA·g^(-1) reached 54.6%,which was approximately 1.5 times higher than that of the pure LaFeO_*** a Ni-modified loose structure not only increased the charge transfer rate on the surface of the LaFeO_3 particles but also enhanced the hydrogen diffusion rate in the bulk LaFeO_3.

关键词： LaFeO3 nickel modification electrochemical performances MH–Ni batteries

Hot Granules Medium Pressure Forming Process of AA7075 Conical Parts

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Chinese Journal of Mechanical Engineering 2015年第3期28卷 580-591页

作者： DONG Guojiang ZHAO Changcai PENG Yaxin LI Ying College of Vehicles and Energy Yanshan University Key Laboratory of Advanced Forging & Stamping Technology and Science of Ministry of Education Yanshan University

High strength aluminum alloy plate has a low elongation at room temperature, which leads to the forming of its components need a high temperature. Liquid or gas is used as the pressure-transfer medium in the existing flexible mould forming process, the heat resistance of the medium and pressurizing device makes the application of aluminum alloy plate thermoforming restricted. To solve this problem, the existing medium is replaced by the heat-resisting solid granules and the general pressure equipments are applied. Based on the pressure-transfer performance test of the solid granules medium, the feasibility that the assumption of the extended Drucker-Prager linear model can be used in the finite element analysis is proved. The constitutive equation, the yield function and the theoretical forming limit diagram（FLD） of AA7075 sheet are established. Through the finite element numerical simulation of hot granules medium pressure forming（HGMF） process, not only the influence laws of the process parameters, such as forming temperature, the blank-holder gap and the diameter of the slab, on sheet metal forming performance are discussed, but also the broken area of the forming process is analyzed and predicted, which are coincided with the technological test. The conical part whose half cone angle is 15° and relative height H/d0 is 0.57, is formed in one process at 250℃. The HGMF process solves the problems of loading and seal in the existing flexible mould forming process and provides a novel technology for thermoforming of light alloy plate, such as magnesium alloy, aluminium alloy and titanium alloy.

关键词： granules medium aluminum alloy sheet drawing hot forming forming limit diagram

Effect of rare earth alloying on creep rupture of economical 21Cr-11Ni-N heat-resistant austenitic steel at 650 ℃

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Journal of Rare Earths 2016年第4期34卷 447-452页

作者：陈雷龙红军刘鑫刚金淼马筱聪 National Engineering Research Center for Equipment and Technology of Cold Strip Rolling Yanshan University School of Mechanical Engineering Yanshan University

The effect of rare earth（RE） on creep rupture of economical 21Cr-11Ni-N heat-resistant austenitic steel was investigated at 650 °C under different stress levels. It was found that RE could increase the time to creep rupture, especially at long-term creep duration. The logarithm of the time to creep rupture（lgtr） was a linear function of the applied stress（σ）. RE addition was favorable to generating a high fraction of low-coincidence site lattice（CSL） boundaries which was a possible cause for improving the creep rupture resistance. The fracture surface of RE-added steel exhibited less intergranular cracks suggesting the alteration on the nature of grain boundaries due to the presence of RE. RE addition changed the morphology of the intergranular chromium carbides from continuous network shape to fragmentary distribution which was another cause for longer creep duration. These results strongly suggested that the effect of RE alloying played a crucial role in improving the creep rupture resistance.

关键词： heat-resistant austenitic steel rare earths alloying creep rupture

ISAR imaging based on improved phase retrieval algorithm

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Journal of Systems Engineering and Electronics 2018年第2期29卷 278-285页

作者： SHI Hongyin XIA Saixue TIAN Ye School of Information Science and Engineering Yanshan University

Traditional inverse synthetic aperture radar(ISAR)imaging methods for maneuvering targets have low resolution and poor capability of noise suppression. An ISAR imaging method of maneuvering targets based on phase retrieval is proposed,which can provide a high-resolution and focused map of the spatial distribution of scatterers on the target. According to theoretical derivation, the modulus of raw data from the maneuvering target is not affected by radial motion components for ISAR imaging system, so the phase retrieval algorithm can be used for ISAR imaging problems. However, the traditional phase retrieval algorithm will be not applicable to ISAR imaging under the condition of random noise. To solve this problem, an algorithm is put forward based on the range Doppler(RD) algorithm and oversampling smoothness(OSS) phase retrieval algorithm. The algorithm captures the target information in order to reduce the influence of the random phase on ISAR echoes, and then applies OSS for focusing imaging based on prior information of the RD algorithm. The simulated results demonstrate the validity of this algorithm, which cannot only obtain high resolution imaging for high speed maneuvering targets under the condition of random noise, but also substantially improve the success rate of the phase retrieval algorithm.

关键词： inverse synthetic aperture radar(ISAR) maneuvering target autofocus imaging phase retrieval oversampling smoothness(OSS)

Structural,electronic,and optical properties of hexagonal and triangular SiC NWs with different diameters

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Chinese Physics B 2017年第4期26卷 433-437页

作者：李彦景李亚林李树龙龚裴房晓勇 School of Science Yanshan UniversityQinhuangdao 066004China Liren College Yanshan UniversityQinhuangdao 066004China

Silicon carbide（SiC） is a wideband gap semiconductor with great application prospects,and the SiC nanomaterials have attracted more and more attention because of their unique photoelectric *** to the first-principles calculations,we investigate the effects of diameter on the electronic and optical properties of triangular SiC NWs（T-NWs）and hexagonal SiC NWs（H-NWs）.The results show that the structure of H-NWs is more stable than T-NWs,and the conduction band bottom of H-NWs is more and more deviated from the valence band top,while the conduction band bottom of T-NWs is closer to the valence band *** is more,H-NWs and T-NWs have anisotropic optical *** result may be helpful in developing the photoelectric materials.

关键词： silicon carbon nanowires stability electronic properties optical properties first-principles theory

SAR Slow Moving Target Imaging Based on Over-Sampling Smooth Algorithm

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Chinese Journal of Electronics 2017年第4期26卷 876-882页

作者： SHI Hongyin YANG Xiaoyan ZHOU Qiuxiao LIAN Qiusheng College of Information Science and Engineering Yanshan University

A novel Synthetic aperture radar(SAR)signal processing technique has been proposed which refocused slow moving targets based on phase retrieval algorithm. After theoretical derivation, we can get that the raw data Fourier magnitude of slow moving targets is approximate to the stationary ones in the SAR system. By applying the Fourier magnitude of received data to phase retrieval algorithms, the blur and defocusing effect caused by the moving of the targets can be eliminated. The simulated results demonstrate the validity of this algorithm.

关键词： Synthetic aperture radar Slow moving target imaging Phase retrieval Over-sampling smooth

Preparation technology and anti-corrosion performances of black ceramic coatings formed by micro-arc oxidation on aluminum alloys

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Rare Metals 2006年第Z2期25卷 146-149页

作者： CHEN Ling HAN Jing YU Shengxue Department of Applied Chemistry Yanshan University Qinhuangdao 066004 China Department of Applied Chemistry Yanshan University Qinhuangdao 066004 China Department of Applied Chemistry Yanshan University Qinhuangdao 066004 China

In order to prepare ornamental and anti-corrosive coating on aluminum alloys, preparation technology of black micro-arc ceramic coatings on Al alloys in silicate based electrolyte was studied. The influence of content of Na2WO4 and combination additive in solution on the performance of black ceramic coatings was studied; the anticorrosion performances of black ceramic coatings were evaluated through whole-immersion test and electrochemical method in 3.5% NaCl solution at different pH value; SEM and XRD were used to analyze the surface morphology and phase constitutes of the black ceramic coatings. Experimental results indicated that, without combination additives, with the increasing of Na2WO4 content in the electrolyte, ceramic coating became darker and thicker, but the color was not black; after adding combination additive, the coating turned to be black; the black ceramic coating was multi-hole form in surface. There was a small quantity of tungsten existing in the black ceramic coating beside α-Al2O3 phase and β-Al2O3 phase. And aluminum alloy with black ceramic coating exhibited excellent anti-corrosion property in acid, basic and neutral 3.5% NaCl solution.

关键词： aluminum alloy micro-arc oxidation black coating anti-corrosion performance