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Preparation of porous titanium materials by powder sintering process and use of space holder technique

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Journal of Iron and Steel Research International 2017年第1期24卷 97-102页

作者： Xin-sheng Wang Zhen-lin lu Lei Jia Jiang-xian Chen School of Materials Science and Engineering Xi'an University of TechnologyXi'an 710048ShaanxiChina

It is shown that an adapted powder sintering process can successfully prepare a 24.0%-35.5% porous titanium composite using 20μm Ti powder and rice husk particles ranging in size between 250μm and600μ*** phase constituents of the porous Ti composite samples were determined by X-ray diffraction（XRD）pattern sintered at 1250℃.The generation of silicon in the form of a TiSi2 solid solution,injected into the substrate,illustrates the solid solution strengthening *** average grain size of the tested sample and the grain boundary area increase along with the silicon *** indicates that silicon is dispersed within the green compact of *** the distance from a hole becomes greater,the nanohardness increases until it reaches a maximum hardness of 3.5GPa at approximately *** may be due to the solid solution strengthening of ***,nanohardness is 3.3GPa at a distance of approximately 0.5mm from a hole′s *** compressive strength is measured to be in the range of 440-938 *** strain reaches 14.8%-16.6% under compression testing.A large number of cleavage steps appear following a *** observed fracture is a brittle *** Ti composites with about 36% porosity have promising potential biomaterial applications,specifically related to bone implants and biological bearings.

关键词： Rice husk Porous Ti Sintering Porosity Hardness Mechanical property

Analysis of delamination in thin film electrodes under galvanostatic and potentiostatic operations with Li-ion diffusion from edge

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Acta Mechanica Sinica 2013年第3期29卷 348-356页

作者： Bo lu Yi-Cheng Song Zhan-sheng Guo Jun-Qian Zhang Shanghai Institute of Applied Mathematics and Mechanics Shanghai University Department of Mechanics Shanghai University Shanghai Key Laboratory of Mechanics in Energy Engineering Shanghai University

Progressive delamination driven by Li-ion diffusion in elastic disk-like thin film electrodes of Li-ion batteries is modeled based on the cohesive model. Axisymmetric diffusion model is considered under both galvanostatic and potentiostatic operations. The effect of edge diffusion on the delamination process is evaluated. It is found that the diffusion from edge leads to an earlier delamination initiation. The edge effect is significant for active disks with a small aspect ratio, but negligible for the case of large aspect ratio. The edge diffusion is weaker in the potentiostatic operation than in the galvanostatic operation.

关键词： Lithium-ion battery · Thin film electrode · De-lamination · Diffusion

Quantitative assessment of the surface crack density in thermal barrier coatings

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Acta Mechanica Sinica 2014年第2期30卷 167-174页

作者： Li Yang Zhi-Chun Zhong Yi-Chun Zhou Chun-sheng lu Key Laboratory of Low Dimensional Materials & Application Technology (Ministry of Education)/Faculty of Materials Optoelectronic & PhysicsXiangtan University Department of Mechanical Engineering Curtin University

In this paper, a modified shear-lag model is developed to calculate the surface crack density in thermal barrier coatings（TBCs）. The mechanical properties of TBCs are also measured to quantitatively assess their surface crack density. Acoustic emission（AE） and digital image correlation methods are applied to monitor the surface cracking in TBCs under tensile loading. The results show that the calculated surface crack density from the modified model is in agreement with that obtained from experiments. The surface cracking process of TBCs can be discriminated by their AE characteristics and strain evolution. Based on the correlation of energy released from cracking and its corresponding AE signals, a linear relationship is built up between the surface crack density and AE parameters, with the slope being dependent on the mechanical properties of TBCs.

关键词： Thermal barrier coatings Acoustic emission Surface crack density Quantitative assessment

Multiple assessments, source determination, and health risk apportionment of heavy metal(loid)s in the groundwater of the Shule River Basin in northwestern China

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Journal of Arid Land 2023年第11期15卷 1355-1375页

作者： WEN Xiaohu LI Leiming WU Jun lu Jian sheng Danrui Key Laboratory of Ecological Safety and Sustainable Development in Arid Lands Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000China Key Laboratory of Comprehensive and Highly Efficient Utilization of Salt Lake Resources Qinghai Institute of Salt LakesChinese Academy of SciencesXining 810008China Yantai Research Institute Harbin Engineering UniversityYantai 264006China Shandong Key Laboratory of Coastal Environmental Processes/CAS Key Laboratory of Coastal Environmental Processes and Ecological Remediation Chinese Academy of SciencesYantai 264003China

Global ecosystems and public health have been greatly impacted by the accumulation of heavy metal(loid)s in ***-specific risk apportionment is needed to prevent and manage potential groundwater contamination with heavy metal(loid)*** heavy metal(loid)s contamination status,water quality,ecological risk,and health risk apportionment of the Shule River Basin groundwater are poorly ***,field sampling was performed to explore the water quality and risk of heavy metal(loid)s in the groundwater of the Shule River Basin in northwestern China.A total of 96 samples were collected from the study area to acquire data for water quality and heavy metal(loid)s *** was noticeable accumulation of ferrum in the groundwater of the Shule River *** levels of pollution were considered to be moderately low,as evaluated by the degree of contamination,heavy metal evaluation index,heavy metal pollution index,and Nemerow pollution *** ecological risks were also ***,an assessment of the water quality index revealed that only 58.34%of the groundwater samples had good water *** absolute principal component scores-multiple linear regression model was more suited for this study area than the positive matrix factorization *** were no obvious noncarcinogenic or carcinogenic concerns for all types of receptors according to the values of the total hazard index and total carcinogenic *** human activities and the initial geological environment factor(65.85%)was the major source of noncarcinogenic risk(residential children:87.56%;residential adults:87.52%;recreational children:86.77%;and recreational adults:85.42%),while the industrial activity factor(16.36%)was the major source of carcinogenic risk(residential receptors:87.96%;and recreational receptors:68.73%).These findings provide fundamental and crucial information for reducing the health issues caused by heavy metal(loid)s contamination of groundwater in arid areas.

关键词： groundwater heavy metal(loid)s ecological risk health risk Shule River Basin

Securing offshore resources development:A mathematical investigation into gas leakage in long-distance flexible pipes

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Petroleum Science 2024年第4期21卷 2734-2744页

作者： Xiang-An lu Liang-Liang Jiang Jian-sheng Zhang Min-Gui Wang Guangling College of Yangzhou University Yangzhou225131JiangsuChina Department of Chemical and Petroleum Engineering University of CalgaryCalgaryT2N 1N4AlbertaCanada Department of Energy and Power Engineering Tsinghua UniversityBeijing100084China

Gas flexible pipes are critical multi-layered equipment for offshore oil and gas *** high pressure conditions,small molecular components of natural gas dissolve into the polymer inner liner of the flexible pipes and further diffuse into the annular space,incurring annular pressure build-up and/or production of acidic environment,which poses serious challenges to the structure and integrity of the flexible *** permeation in pipes is a complex phenomenon governed by various factors such as internal pressure and temperature,annular structure,external *** a long-distance gas flexible pipe,moreover,gas permeation exhibits non-uniform features,and the gas permeated into the annular space flows along the metal *** assess the complex gas transport behavior in long-distance gas flexible pipes,a mathematical model is established in this paper considering the multiphase flow phenomena inside the flexible pipes,the diffusion of gas in the inner liner,and the gas seepage in the annular space under varying permeable properties of the *** addition,the effect of a variable temperature is accounted.A numerical calculation method is accordingly constructed to solve the coupling mathematical *** annular permeability was shown to significantly influence the distribution of annular *** permeability increases,the annular pressure tends to become more uniform,and the annular pressure at the wellhead rises more *** annular pressure relief followed by shut-in,the pressure increase follows a convex *** simulating the pressure recovery pattern after pressure relief and comparing it with test results,we deduce that the annular permeability lies between 123 and 512 m *** results help shed light upon assessing the annular pressure in long distance gas flexible pipes and thus ensure the security of gas transport in the emerging development of offshore resources.

关键词： Offshore resources development Transport security Long-distance flexible pipes Gas leakage Heat and mass transfer model Finite difference calculation

Photoluminescence Properties of Nanocrystalline 3C-SiC Films

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Chinese Journal of Aeronautics 2006年第B12期19卷 215-219页

作者： YUWei lu Xue-qin lu Wan-bing HAN Li FU Guang-sheng College of Physics Science and Technology Hebei University Baoding 071002 China

Nanocrystalline （nc） 3C-SiC films on the Si substrate were prepared by the helicon wave plasma enhanced chemical vapor deposition （HW-PECVD） technique. With the SiH4-CH4 gas flow ratio changing, the films exhibit different photoluminescence （PL） characteristics. Under the stoichiometric condition, the PL peak redshift from 470 nm to 515 nm is detected with the increase of excitation wavelength, which can be attributed to the quantum confinement effect radiation of 3C-SiC nanocrystals of different sizes. However, the appearance of an additional PL band at 436 nm in Si-rich film might be sourced back to the excess of Si defect centers in it. This is also the case for C-rich film for its PL band lying at 570 nm. The results above quoted indicate an important influence of gas flow ratio on the PL properties of the SiC films providing an effective guidance for analyzing the luminescence mechanism and exploring the high-efficiency light emission of the SiC films.

关键词： SiC film photoluminescence quantum confinement effect defect

Neighbor Sum Distinguishing Total Choosability of Planar Graphs with Maximum Degree at Least 10

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Acta Mathematicae Applicatae Sinica 2024年第1期40卷 211-224页

作者： Dong-han Zhang You lu sheng-gui Zhang Li Zhang School of Mathematics and Statistics Northwestern Polytechnical UniversityXi’an710129China School of Mathematics and Computer Application Shangluo UniversityShangluo726000China

A neighbor sum distinguishing(NSD)total coloringφof G is a proper total coloring of G such thatΣz∈EG(u)U{u}φ(z)≠Σz∈EG(v)U{v}φ(z)for each edge uv∈E(G),where EG(u)is the set of edges incident with a vertex *** 2015,Pilśniak and Wozniak conjectured that every graph with maximum degreeΔhas an NSD total(Δ+3)-***,Yang et *** that the conjecture holds for planar graphs withΔ≥10,and Qu et *** that the list version of the conjecture also holds for planar graphs withΔ≥*** this paper,we improve their results and prove that the list version of the conjecture holds for planar graphs withΔ≥10.

关键词： planar graphs neighbor sum distinguishing total choosibility combinatorial nullstellensatz discharging method

Stellar dynamical modeling-accuracy of 3D density estimation for edge-on axisymmetric galaxies

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Research in Astronomy and Astrophysics 2021年第6期21卷 403-423页

作者： Richard J.Long sheng-Dong lu Dan-Dan Xu Department of Astronomy Tsinghua UniversityBeijing 100084China Jodrell Bank Centre for Astrophysics Department of Physics and AstronomyThe University of ManchesterOxford RoadManchester M139PLUK

From Rybicki’s analysis using the Fourier slice theorem,mathematically it is possible to reproduce uniquely an edge-on axisymmetric galaxy’s 3D light distribution from its 2D surface *** galaxies from a cosmological simulation,we examine the ability of Syer and Tremaine’s madeto-measure method and Schwarzschild’s method for stellar dynamical modeling to do so for edge-on oblate axisymmetric ***,we find that the methods do not accurately recover the 3D distributions,with the made-to-measure method producing more accurate estimates than Schwarzschild’s *** results have implications broader than just luminosity density,and affect other luminosity-weighted distributions within galaxies,for example,age and metallicity.

关键词： galaxies:kinematics and dynamics galaxies:structure methods:numerical

Crack behavior in Mg/Al alloy thin sheet during hot compound extrusion

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Journal of Magnesium and Alloys 2019年第4期7卷 717-724页

作者： Kun sheng Liwei lu Yao Xiang Min Ma Zhiqiang Wu Hunan Provincial Key laboratory of High Efficiency and Precision Machining of Difficult-to-Cut Material Hunan University of Science and TechnologyXiangtanHunan 411201PR China College of Materials Science and Engineering Hunan University of Science and TechnologyXiangtanHunan 411201PR China Hunan Provincial Overseas-wisdom Innovation Center of New Energy Vehicle in Industrial-Academic-Research Cooperation Hunan University of Science and TechnologyXiangtanHunan 411201PR China

A novel and effective method to co-extrude metallic alloys is described which named Direct Extrusion and Bending-Shear *** compound extrusion plates have cracked at 290℃ and 3 mm/*** to this phenomenon,a model was built to investigate the crack generation and development between the 6061 Al and AZ31 Mg alloy during the compound extrusion process by *** cracking behavior of the Mg/Al composite rod with a soft Mg AZ31 core and a hard Al 6061 sleeve were systematically studied to disclose the influence of microstructure on crack in the different *** simulation results show that the distribution of strain and velocity has significant differences due to the influence of dies structure and material properties at different locations in the same *** experimental results show that in the same conditions,there are differences in recrystallization and texture weakening of AZ31 Mg alloys and 6061 Al alloy,which are important factors for the formation of *** the Mg layer and the Al layer have a homogeneous microstructure in the region d.

关键词： AZ31 Mg alloy 6061 Al alloy Compound extrusion Crack EBSD