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Precipitation Characteristics and Mechanism of Vanadium Carbides in a V-Microalloyed Medium-Carbon Steel

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Acta Metallurgica Sinica(English Letters) 2018年第11期31卷 1197-1206页

作者： xiao-Lin pan Minoru Umemoto School of Metallurgy Northeastern University Department of Mechanical Engineering Toyohashi University of Technology

The precipitation characteristics and mechanism of vanadium carbides during isothermal transformation at 650℃ in aV-microalloyed medium-carbon steel were investigated through scanning electron microscopy and transmission electronmicroscopy as well as dilatometry test. Five morphologies of vanadium carbides were found to precipitate at differentnucleation sites during the transformation. Two kinds of interphase precipitation form simultaneously in both pro-eutectoidand pearlitic ferrites. The linear arrays of fine interphase precipitates are parallel to the γ/α interface, and the fine needles ofinterphase precipitates are perpendicular to the 7/ct interface. The vanadium carbides of long or short fibers, coarse particlesand fine particles form in both pro-eutectoid and pearlitic ferrites, displaying different precipitation distributions andorientation relationships with ferrite. The precipitation mechanisms of vanadium carbide precipitates with different modeswere proposed, and the precipitation sequence of various vanadium carbide precipitates was finally ascertained.

关键词： Microalloyed steels Carbide precipitation Isothermal transformation Precipitation sequence Orientation relationship

Phase evolution of binary immiscible Al-Sn film

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Rare Metals 2022年第12期41卷 4241-4247页

作者： xiao-Meng pan Hui-Ping Duan School of Materials Science and Engineering Beihang UniversityBeijing 100191China

Binary immiscible Al-Sn alloy is a very important potential anode material for lithium ion *** phase stability and separation process of Al-Sn film,fabricated by magnetron co-sputtering method,was investigated by X-ray diffractometer(XRD),differential scanning calorimetry(DSC) and in situ transmission electron microscopy(TEM) and explained by Miedema theoretical *** analysis reveals that the asdeposited Al-Sn film will decompose spontaneously into Al-riched areas and Sn-riched areas because of the positive mixing *** crystallization process takes place when the Al content in the Al-riched area or Sn content in the Sn-riched area *** results show that Al-Sn thin film is composed of an amorphous matrix and well-dispersed composite *** particle contains an Al-riched area and a Sn-riched *** Snriched area crystallizes and swallows up the Al-riched area gradually during heating through uphill diffusion of the Sn *** on the theoretical analysis and experimental results,an empirical model to explain the phase evolution process in the Al-Sn film was proposed.

关键词： Immiscible alloy Uphill diffusion Phase evolution Miedema theory

Efficient and Reliable Nanoindentation Simulation by Dislocation Loop Erasing Method

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Acta Mechanica Solida Sinica 2020年第5期33卷 586-599页

作者： Fei Shuang pan xiao Yilong Bai LNM Institute of MechanicsChinese Academy of SciencesBeijing100190China Department of Mechanical and Aerospace Engineering University of FloridaGainesvilleFL32611USA

Nanoindentation is a useful technique to measure material properties at microscopic ***,the intrinsically multiscale nature makes it challenging for large-scale simulations to be carried *** is shown that in molecular statics simulations of nanoindentation,the separated dislocation loops(SDLs)are trapped in simulation box which detrimentally affects the plastic behavior in the plastic zone(PZ);and the long-distance propagation of SDLs consumes much computational cost yet with little contribution to the variation of tip *** tackle the problem,the dislocation loop erasing(DLE)method is proposed in the work to alleviate the influence of artificial boundary conditions on the SDL–PZ interaction and improve simulation *** results indicate that the force–depth curves obtained from simulations with and without DLE are consistent with each other,while the method with DLE yields more reasonable results of microstructural evolution and shows better *** new method provides an alternative approach for large-scale molecular simulation of nanoindentation with reliable results and higher efficiency and also sheds lights on improving existing multiscale methods.

关键词： Nanoindentation Dislocation loops Boundary effects Molecular statics

Dynamic model of multi-agent social evolutionary algorithm and its convergence

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The Journal of China Universities of Posts and Telecommunications 2013年第6期20卷 122-128页

作者： pan xiao-ying CHEN Hao School of Computer Science & Technology Xi'an University of Posts & Telecommunications

With a typical and simple 2-bit problem, a dynamic model of multi-agent social evolutionary algorithm （MASEA） is constructed by dynamic method. Then, the global dynamic shape of MASEA is comprehensively analyzed and the common evolution operators are also formally described. Furthermore, the effect that every evolutionary operator has on the dynamic shape is discovered by attraction analysis of the fixed points in the models. The global convergence of MASEA is also proved.

关键词： multi-agent social evolutionary algorithm fixed point attractive point attractiveness

Mineral transition and formation mechanism of calcium aluminate compounds in CaO-Al2O3-Na2O system during high-temperature sintering

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International Journal of Minerals,Metallurgy and Materials 2020年第7期27卷 924-932页

作者： Hai-yan Yu xiao-lin pan Yong-pan Tian Gan-feng Tu School of Metallurgy Northeastern UniversityShenyang 110819China

The mineral transition and formation mechanism of calcium aluminate compounds in CaO-Al2O3-Na2O system during the hightemperature sintering process were systematically investigated using DSC-TG,XRD,SEM-EDS,FTIR,and Raman spectra,and the crystal structure of Na4Ca3(AlO2)10 was also simulated by Material Studio *** results indicated that the minerals formed during the sintering process included Na4Ca3(AlO2)10,CaO·Al2O3,and 12 CaO·7 Al2O3,and the content of Na4Ca3(AlO2)10 could reach 92 wt%when sintered at 1200°C for 30 *** main formation stage of Na4Ca3(AlO2)10 occurred at temperatures from 970 to 1100°C,and the content could reach82 wt%when the reaction temperature increased to 1100°*** crystal system of Na4Ca3(AlO2)10 was tetragonal,and the cells preferred to grow along crystal planes(110)and(210).The formation of Na4Ca3(AlO2)10 was an exothermic reaction that followed a secondary reaction model,and its activation energy was 223.97 kJ/mol.

关键词： calcium aluminate sodium oxide crystal structure formation kinetics sintering

Exploiting user behavior learning for personalized trajectory recommendations

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Frontiers of Computer Science 2022年第3期16卷 141-152页

作者： xiao pan Lei WU Fenjie LONG Ang MA School of Economics and Management Shijiazhuang Tiedao UniversityShijiazhuang 050043China

With increasing popularity of mobile devices and flourish of social networks,a large number of trajectory data is *** data contains a wealth of information,including spatiality,time series,and other external descriptive attributes(i.e.,travelling mode,activities,etc.).Trajectory recommendation is especially important to users for finding the routes meeting the user’s travel needs *** existing trajectory recommendation works return the same route to different users given an origin and a ***,the users’behavior preferences can be learned from users’historical multi-attributes *** this paper,we propose two novel personalized trajectory recommendation methods,i.e.,user behavior probability learning based on matrix decomposition and user behavior probability learning based on Kernel density *** transform the route recommendation problem to a shortest path problem employing Bayesian probability *** the user input(i.e.,an origin and a destination),the trajectory query is performed on a behavior graph based on the learned behavior probability ***,a series of experiments on two real datasets validate the effectiveness of our proposed methods.

关键词： trajectory recommendation big trajectory data trajectory computing geo-social networks

Observational Constraints on Quark Matter in Neutron Stars

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Chinese Journal of Astronomy and Astrophysics 2007年第5期7卷 675-684页

作者： Na-Na pan xiao-Ping Zheng Institute of Astrophysics Huazhong Normal University Wuhan 430079

We study the observational constraints of mass and redshift on the properties of the equation of state （EOS） for quark matter in compact stars based on the quasi-particle description. We discuss two scenarios; strange stars and hybrid stars. We construct the equations of state utilizing an extended MIT bag model taking the medium effect into account for quark matter and the relativistic mean field theory for hadron matter. We show that quark matter may exist in strange stars and in the interior of neutron stars. The bag constant is a key parameter that affects strongly the mass of strange stars. The medium effect can lead to the stiffer hybrid-star EOS approaching the pure hadronic EOS, due to the reduction of quark matter, and hence the existence of heavy hybrid stars. We find that a middle range coupling constant may be the best choice for the hybrid stars being compatible with the observational constraints.

关键词： dense matter -- gravitation -- stars neutron -- stars rotation -- stars oscillations

Distribution characteristics of inclusions along with the surface sliver defect on the exposed panel of automobile:A quantitative electrolysis method

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International Journal of Minerals,Metallurgy and Materials 2020年第11期27卷 1489-1498页

作者： xiao-qian pan Jian Yang Joohyun Park Hideki Ono State Key Laboratory of Advanced Special Steel School of Materials Science and EngineeringShanghai UniversityShanghai 200444China Department of Materials Engineering Hanyang UniversityAnsan 426-791South Korea Faculty of Sustainable Design University of ToyamaToyama-ken 930-8555Japan

The specific distribution characteristics of inclusions along with the sliver defect were analyzed in detail to explain the formation mechanism of the sliver defect on the automobile exposed panel surface.A quantitative electrolysis method was used to compare and evaluate the three-dimensional morphology,size,composition,quantity,and distribution of inclusions in the defect and non-defect zone of automobile exposed *** Al2O3 inclusions were observed to be aggregated or chain-like shape along with the sliver defect of about 3–10μ*** aggregation sections of the Al2O3 inclusions are distributed discretely along the rolling direction,with a spacing of 3–7 mm,a length of 6–7 mm,and a width of about 3 *** inclusion area part is 0.04%–0.16%with an average value of 0.08%,the inclusion number density is 40 mm−2 and the inclusion average spacing is 25.13μ*** inclusion spacing is approximately 40–160μm,with an average value of 68.76μm in chain-like inclusion *** average area fraction and number density of inclusions in the non-defect region were reduced to about 0.002%and 1–2 mm^−2,respectively,with the inclusion spacing of 400μm and the size of Al2O3 being 1–3μm.

关键词： automobile exposed panel sliver defect quantitative electrolysis three-dimensional inclusions aggregated inclusions chain-like inclusions

Efficient tensor decomposition method for noncircular source in colocated coprime MIMO radar

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Chinese Physics B 2020年第5期29卷 333-345页

作者： Qian-Peng Xie xiao-Yi pan Shun-Ping xiao National University of Defense Technology Changsha 410073China

An effective method via tensor decomposition is proposed to deal with the joint direction-of-departure(DOD)and direction-of-arrival(DOA)estimation of noncircular sources in colocated coprime MIMO *** decomposing the transmitter and receiver into two sparse subarrays,noncircular property of source can be used to construct new extended received signal model for two sparse *** new received model can double the virtual array aperture due to the elliptic covariance of imping sources is *** further exploit the multidimensional structure of the noncircular received model,we stack the subarray output and its conjugation according to mode-1 unfolding and mode-2 unfolding of a third-order tensor,***,the corresponding extended tensor model consisted of noncircular information for DOA and DOD can be ***,the higher-order singular value decomposition technique is utilized to estimate the accurate signal subspace and angular parameter can be automatically paired via the rotational invariance ***,the ambiguous angle can be eliminated and the true targets can be achieved with the aid of the coprime ***,a closed-form expression for the deterministic CRB under the NC sources scenario is also *** results verify the superiority of the proposed estimator.

关键词： colocated coprime MIMO radar noncircular signal tensor decomposition DOD and DOA estimation