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Nd3-xAExFe5O12： Hydrothermal Synthesis, Structure and Magnetic Properties

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Chemical Research in Chinese Universities 2017年第6期33卷 869-875页

作者： WU Jie yuan Long WANG shan HOU Changmin State Key Laboratory of Inorganic Synthesis and Preparative Chemistry College of Chemistry Jilin University Changchun 130012 P. R. China Department of Materials Science and Engineering Jilin Institute of Chemical Technology Jilin 132022 P. R. China

Rare-earth ferrite garnet is one of the most important materials applied in microwave transducer and in- frared magneto-optical devices, etc. Nd3-xAExFe5O12（AE=Ca, Sr） crystals, which have cubic structure with the space group ofIa-3 d and lattice constants over 1.26 nm, were prepared via the mild hydrothermal method. The structural, morhpology and magnetic properties were characterized by means of powder X-ray diffraction, scanning electronic microscopy, as well as vibrating sample magnetometer and M6ssbauer spectroscopy, respectively. M6ssbaner spectroscopy demonstrates the coexistence of Sr2＋, Ca2＋ and Nd3＋ at the C sites of the dodecahedrons for different substituted garnets. The crystal shape is dodecahedron, and the particle sizes are decreased with increasing the Ca and Sr doping concentrations. By recording the magnetic hysteresis loops and M-T curves at different temperatures, it can be seen that with the increasing x, the saturation magnetization values decrease while the coercive forces increase under the condition of high temperatures.

关键词： Garnet structure Magnetic property M6ssbauer spectrum

Additive Hazards Regression with Random Effects for Clustered Failure Times

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Acta Mathematica Sinica,English Series 2015年第3期31卷 511-525页

作者： Deng PAN Yan Yan LIU yuan shan WU Department of Statistics Chinese University of Hong Kong School of Mathematics and Statistics Wuhan University

Additive hazards model with random effects is proposed for modelling the correlated failure time data when focus is on comparing the failure times within clusters and on estimating the correlation between failure times from the same cluster, as well as the marginal regression parameters. Our model features that, when marginalized over the random effect variable, it still enjoys the structure of the additive hazards model. We develop the estimating equations for inferring the regression parameters. The proposed estimators are shown to be consistent and asymptotically normal under appropriate regularity conditions. Furthermore, the estimator of the baseline hazards function is proposed and its asymptotic properties are also established. We propose a class of diagnostic methods to assess the overall fitting adequacy of the additive hazards model with random effects. We conduct simulation studies to evaluate the finite sample behaviors of the proposed estimators in various scenarios. Analysis of the Diabetic Retinopathy Study is provided as an illustration for the proposed method.

关键词： Additive hazards regression clustered failure times counting process empirical process,frailty model checking random effects

A new method of dynamic mesh used in continuous guide vane closure of a reversible pump-turbine in generating mode

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Journal of Hydrodynamics 2019年第5期31卷 976-985页

作者： Xiu-li Mao yuan Zheng Giorgio Pavesi Zhan-shan Xie College of Water Resources and Architectural Engineering Northwest A&F UniversityYangling 712100China College of Water Conservancy and Hydropower Engineering Hohai UniversityNanjing 210098China Department of Industrial Engineering University of PaduaPadovaItaly

In this paper,a new method of dynamic mesh based on two functional controls is used in the continuous guide vane closure,and the three-dimensional numerical simulation is carried out to investigate the transient flow characteristics for a Francis-type reversible pump-turbine in the turbine mode in the load regulation scenario,with the detached eddy simulation(DES)turbulent *** transient flow characteristics during the closure of the guide vanes are illustrated by analyzing the signals of the mass flow,the torque and the pressure fluctuations in the frequency and time-frequency *** is shown by the simulated results that a continuous assessment of the transient flow characteristics during the guide vane closure may be made by using the new method of the dynamic ***,the flow field analysis involves both the onset and the development of the unsteady phenomena progressively based on an organized guide vane closure *** flow pattern in the return channel maintains a relatively stable flow field before the last stage of the closure,as compared with the unstable flow field in other *** identify the unit variation under the fluid-dynamical conditions,the influence of the three-dimensional unsteady flow structures in the passage is analyzed and its evolution during this transient process is characterized by the fluid-dynamics and the spectral analysis.

关键词： Francis-type reversible turbine dynamic mesh guide vane closure flow characteristics

Polybrominated diphenyl ethers in soil from three typical industrial areas in Beijing, China

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Journal of Environmental Sciences 2013年第12期25卷 2443-2450页

作者： Yongfei Zhang shan Fu Xinchun Liu Zheng Li yuan Dong State Key Laboratory of Environmental Chemistry and Ecotoxicology Research Center for Eco-Environmental SciencesChinese Academy of Sciences University of Chinese Academy of Sciences

Areas containing industrial facilities belonging to three different typical industries that may cause pollution by polybrominated diphenyl ethers （PBDEs） in Beijing, China were investigated. Specifically, the areas contained a solid waste incineration plant, a chemical factory, and a heat and power plant. Investigation of the pollution status of PBDEs in the surface soil from areas around these industries revealed the highest concentration of 42 PBDE congeners （118 ng/g, dry mass） at the solid waste incineration plant. In the other two plants, the highest concentrations were both 26 ng/g （dry mass）. Among the PBDE homologues, the PBDE contamination at all sites showed similar congener compositions, with BDE 209 being the dominant congener. Our findings established the first contamination status of three typical industrial areas in Beijing. Furthermore, the total concentrations of 42 PBDE congeners tended to decrease as the distance from the investigated plants increased. Overall, these plants were identified as potential pollution sources of PBDEs in Beijing. Moreover, Pearson correlation analysis revealed that the major PBDE source in Beijing may be associated with the technical deca-BDE and penta-BDE mixture. Based on the data obtained in this preliminary investigation, further study of the potential of these sources to emit PBDEs in Beijing is warranted.

关键词： different industry areas pollution source polybrominated diphenyl ethers soil

Toric Difference Variety

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Journal of Systems Science & Complexity 2017年第1期30卷 173-195页

作者： GAO Xiao-shan HUANG Zhang WANG Jie yuan Chun-Ming Key Laboratory of Mathematics Mechanization Academy of Mathematics and Systems ScienceChinese Academy of Sciences Department of Applied Mathematics Chengdu University of Technology

In this paper, the concept of toric difference varieties is defined and four equivalent descriptions for toric difference varieties are presented in terms of difference rational parametrization,difference coordinate rings, toric difference ideals, and group actions by difference tori. Connections between toric difference varieties and affine N[x]-semimodules are established by proving the one-to-one correspondence between irreducible invariant difference subvarieties and faces of N[x]-semimodules and the orbit-face correspondence. Finally, an algorithm is given to decide whether a binomial difference ideal represented by a Z[x]-lattice defines a toric difference variety.

关键词： Afflne N[x]-semimodule difference torus T-orbit toirc difference ideal toric differencevariety Z[x]-lattice.

Adaptive Penalized Weighted Least Absolute Deviations Estimation for the Accelerated Failure Time Model

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Acta Mathematica Sinica,English Series 2020年第7期36卷 812-828页

作者： Ming Qiu WANG yuan shan WU Qing Long YANG School of Statistics Qufu Normal UniversityQufu 273165P.R.China School of Statistics and Mathematics Zhongnan University of Economics and LawWuhan 430073P.R.China

The accelerated failure time model always offers a valuable complement to the traditional Cox proportional hazards model due to its direct and meaningful *** propose a variable selection method in the context of the accelerated failure time model for survival data,which can simultaneously complete variable selection and parameter ***,the proposed method can deal with the potential outliers in survival times as well as heteroscedastic model errors,which are frequently encountered in ***,utilizing the general nonconvex penalty,we propose the adaptive penalized weighted least absolute deviation estimator for the accelerated failure time *** some regularity conditions,we show that the proposed method yields consistent estimator and possesses the oracle *** addition,we propose a new algorithm to compute the estimate in the high dimensional settings,and evaluate the practical utility of the proposed method through extensive simulation studies and two real examples.

关键词： estimation. property. estimator

Development of L-arginine-based poly(ester urethane)urea for enhanced vascular adaptability

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Science China(Technological Sciences) 2022年第11期65卷 2751-2762页

作者： BAI shan ZHANG XiangYu ZANG LeiLei REN LiXia yuan XiaoYan School of Materials Science and Engineering Tianjin Key Laboratory of Composite and Functional MaterialsTianjin UniversityTianjin300350China

Mismatched biomechanical properties between artificial vascular grafts and native blood vessels can result in intimal hyperplasia,especially for the implantation of small-diameter blood *** biomaterials for vascular repair still remain *** poly(ε-caprolactone)(PCL)has been applied for the preparation of electrospun vascular grafts,but more efforts are needed to improve its compliance with tissue ***,L-arginine-based poly(ester urethane)urea(PEUU)with both elasticity and biodegradability was synthesized so as to enhance the biomechanical properties of vascular grafts by blending electrospinning with PCL in a given mass *** was exhibited that the prepared electrospun PCL/PEUU fibrous membranes were suitable for cell proliferation with normal cell *** importantly,the electrospun membrane with 1/1 mass ratio of PCL/PEUU(PEUU50)showed specific flexibility,exhibiting more suitable mechanical properties matching to the native blood ***,the PEUU50 electrospun membrane demonstrated significantly lower Young’s modulus(9.3±0.8 MPa)and tensile strength(6.0±0.5 MPa),and extremely higher elongation(389%±24%)in wet state than those(16.3±3.0 MPa,11.4±7.1 MPa and 196%±57%,respectively)of the pristine PCL ***,this study demonstrated the great potential of amino acid-based PEUUs for the application in small-diameter vascular grafts.

关键词： poly(ester urethane)urea poly(e-caprolactone) electrospinning vascular grafts mechanical properties

Variant selection of nanocrystalline a phase in metastableβTB8 titanium alloy via electric pulse treatment

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Rare Metals 2023年第8期42卷 2781-2794页

作者： shan-shan Wu Ya Yang yuan-Biao Tan Song Xiang Ya-Li Zhou Min Ma Fei Zhao Wei Shi Guizhou Key Laboratory of Materials Mechanical Behavior and Microstructure College of Materials and MetallurgyGuizhou UniversityGuiyang 550025China College of Materials Science and Engineering Hunan University of Science and TechnologyXiangtan 411201China

In this paper,the metastableβTB8 titanium alloy with nanocrystallineαphase is achieved by electric pulse *** morphology evolution and variant selection of nanocrystallineαphase in metastableβTB8titanium alloy were investigated by using scanning electron microscope(SEM),electron backscattered diffraction(EBSD)and transmission electron microscope(TEM)*** results indicated that the morphologies of the nanocrystallineαphase were mainly triangular clusters and needle-like at the pressure of 0 *** increasing pressure from 20 to 50 MPa,the volume fraction of needlelikeαphase decreased,and a large amount of V-shapedαphase formed in the interior ofβ*** on the EBSD data,the parentβphase was reconstructed by MTEX *** the interior of theβgrains,12 variants can form for the samples electric pulse treated at 0 and20 MPa,while only 3 and 6 variants can form for the samples electric pulse treated at 30 and 50 *** the grain boundary of theβgrains,one or more grain boundaryαvariants can be generated for the samples electric pulse treated at different pressures as long as one of the neighborβgrains follows the Burgers orientation relationship.

关键词： TB8 titanium alloy Parentβgrain reconstruction Morphology ofαphase Variant selection

Numerical analysis of pile–slope stability and the soil arching around two adjacent piles

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Journal of Mountain Science 2022年第11期19卷 3270-3285页

作者： Chien-yuan CHEN Chun-Kai CHANG Yu-shan LIN Department of Civil and Water Resources Engineering National Chiayi UniversityChiayi City 60004Chinese Taipei

Seismic pile–slope stability analysis and the formation mechanism of soil arching have not been well studied. This study used a threedimensional(3D) finite difference to determine soil and pile parameter changes in the static and seismic stability of the pile–slope caused by the interaction between stabilizing piles. Pile–slope stability analysis was performed to determine the optimal design of piles along a slope and the corresponding failure mode involving the formation of soil arching around two adjacent piles. The Factor of Safety(FS) of the slope was evaluated using the shear strength reduction method for static and seismic analyses. The results of the analysis show that suitable pile spacing(S) and a suitable pile diameter(D) in the middle of a slope result in the maximum FS for the pile–slope system and the formation of soil arching around two adjacent piles. FS of the pile–slope increased negligibly in the seismic analysis of piles located at the slope crest and toe. An optimized pile diameter and installation location afforded the maximum FS for the slope that corresponded to a specified slope failure mode for different pile locations. A pile spacing S ≤ 2.5D for piles installed in the middle of the slope is suggested for increasing the static and seismic pile–slope stability.

关键词： Numerical modeling Slope stability Stabilizing pile Arching effect Seismic analysis Failure mode