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Hot Deformation Characteristics for a Nickel-base Superalloy GH742y

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Journal of Materials Science & Technology 2009年第3期25卷 373-378页

作者： Fuwei kang Jianfei Sun Guoqing zhang Zhou Li School of Material Science and Engineering Harbin Institute of Technology Harbin 150001 China School of Material Science and Engineering Harbin University of Science and Technology Harbin 150040 China Beijing Institute of Aeronautical Materials Beijing 100095 China

The hot deformation characteristics of as-cast nickel-base superalloy GH742y after hot isostatic pressing （HIP）（hereafter referred to as-cast alloy） have been investigated by hot compression tests in the temperature range of 1050 to 1140℃, strain rate range of 0.01 s^-1 to 10 s^-1 and strain range of 35% to 50% by means of Gleeble-3500 thermal mechanical simulator. The results show that the as-cast alloy exhibits the poor deformability, and shows wedge-shaped cracking beyond the strain of 35%. At strain rates less than 1.0 s^-1, the stress-strain curves exhibit nearly steady-state behavior, while at strain rate of 10 s^-1, a yield drop and serrated yielding occur. The activation energy values developed on the basis of the experimental data are divided into three domains. The first domain appears at lower strain rate （≤1.0 s^-1） and lower temperature （≤1080℃）, with the lowest mean value of activation energy about 261.4 kJ/mol. The second domain appears at the same strain rate as the first domain, but higher temperature （〉1080℃）, with the intermediate mean value of activation energy about 328.8 k J/tool. The third domain appears at higher strain rate （10 s^-1） and temperature range of 1050 to 1140℃, with the largest mean value of activation energy about 605.05 kJ/mol. Three different constitutive equations are established in corresponding to domains. Microstructural observations in the third domain reveal non-uniform dynamic recrystallization （DRX） of homogeneous γ phase, which leads to the poor deformability and the highest Q value. In contrast, microstructures in the first domain show fully DRX of homogeneous γ phase, leading to the better deformability and the lowest Q value. It is noted that the grain size increases with the increment of strain rate or temperature. These results suggest that bulk metal working of this material may be carried out in the first domain where fully DRX of γ homogeneous occurred.

关键词： Superalloy Hot deformation Constitutive equation Activation energy

Analytical model of friction behavior during polymer scratching with conical tip

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Friction 2019年第5期7卷 466-478页

作者： Chengkai JIANG Han JIANG Jianwei zhang Guozheng kang Applied Mechanics and Structure Safety Key Laboratory of Sichuan Province School of Mechanics and Engineering Southwest Jiaotong University

To investigate the effects of the contact geometry, interfacial friction, and substrate recovery on the behavior of polymer scratching using a conical tip, an analytical model is proposed. The normal stress acting on the contact surface between the tip and the substrate is described as a function of the included angle θ, representing the angle between two planes across the axis of the conical tip, and the attack angle β, representing the angle between the conical surface and the substrate material surface. The effects of the rear contact geometry on the scratch friction between the tip and substrate, represented by recovery angle φ, owing to the instantaneous elastic recovery of the polymer substrate, are also introduced. Validated by the experimental and numerical results from the literature, the proposed analytical model can describe well the scratch coefficient of friction(SCOF), which is defined as the ratio of the tangential force to the normal force. Meaningful guidance is provided to understand the scratch friction behavior.

关键词： polymer scratch contact geometry elastic recovery scratch coefficient of friction

Entanglement Protection of Two-Qubit System in Non-Markovian Reservoir via Weak Measurement and Weak Measurement Reversal

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Chinese Journal of Electronics 2019年第3期28卷 593-597页

作者： GUO Xiuli zhang Yanliang kang Guodong ZHOU Qingping School of Physics and Mechanical and Electrical Engineering Jishou University School of Software and Service Outsourcing Jishou University

The protection schemes of the entanglement in the system of two entangled atoms from nonMarkovian reservoirs via previous Weak measurement(pre-WM) and posterior Weak measurement reversal(post-WMR) are investigated. We firstly compare the effects of combination applying of pre-WM and post-WMR(scheme 1) and twice Weak measurements(WMs)(scheme2) in the condition of different initial entangled *** analysis indicates that the protection performance of scheme 1 is much better than that of scheme 2. The scheme1 was utilized when the system of two entangled atoms suffers from the independent reservoirs. The numerical results show that the combination of pre-WM and postWMR can effectively enhance entanglement and shorten the time of Entanglement sudden death(ESD) in nonMakovain environment. We have found the optimum of WM strengthens is drastically related to the initial entangled state.

关键词： Entanglement protection Weak measurement Weak measurement reversal Non-Makovain environment

Phenomenological study of the anisotropic quark matter in the two-flavor Nambu–Jona–Lasinio model

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Nuclear Science and Techniques 2022年第11期33卷 170-190页

作者： He-Xia zhang Yu-Xin Xiao Jin-Wen kang Ben-Wei zhang Key Laboratory of Quark and Lepton Physics(MOE)and Institute of Particle Physics Central China Normal UniversityWuhan 430079China Guangdong Provincial Key Laboratory of Nuclear Science Institute of Quantum MatterSouth China Normal UniversityGuangzhou 510006China

With the two-flavor Nambu–Jona–Lasinio (NJL) model, we carried out a phenomenological study on the chiral phase structure, mesonic properties, and transport properties of momentum-space anisotropic quark matter. To calculate the transport coefficients we utilized the kinetic theory in the relaxation time approximation, where the momentum anisotropy is embedded in the estimation of both the distribution function and relaxation time. It was shown that an increase in the anisotropy parameterξmay result in a catalysis of chiral symmetry breaking. The critical endpoint(CEP) is shifted to lower temperatures and larger quark chemical potentials asξincreases, and the impact of momentum anisotropy on the CEP temperature is almost the same as that on the quark chemical potential of the CEP. The meson masses and the associated decay widths also exhibit a significant ξ dependence. It was observed that the temperature behavior of the scaled shear viscosity η/T~3 and scaled electrical conductivity σ/T exhibited a similar dip structure, with the minima of both η/T~3 and σ/T shifting toward higher temperatures with increasing ξ. Furthermore,we demonstrated that the Seebeck coefficient S decreases when the temperature rises and its sign is positive, indicating that the dominant carriers for converting the temperature gradient to the electric field are up-quarks. The Seebeck coefficient S is significantly enhanced with a largeξfor a temperature below the critical temperature.

关键词： Heavy-ion collision Momentum anisotropy NJL model Chiral phase transition Transport coefficient Quark matter

Preparation of Durable Emitter of Electrospray Mass Spectrometry by Covalently Coating the Fused-Silica Capillary Tip with Carbon-Nanotube Sol-Gel Composite Material

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Chinese Journal of Chemistry 2014年第4期32卷 293-297页

作者： Hanzhi zhang Chao Liu Xuepei zhang Jingwu kang Shanghai Institute of Organic Chemistry Chinese Academy of SciencesShanghai 200032China

A simple approach for the preparation of emitter of electrospray ionization mass spectrometry by covalently coating the fused-silica capillary tip with the conductive carbon-nanotube sol-gel composite material(CNTSCM)is *** CNTSCM was prepared by dispersing single-walled carbon nanotubes in the sol composed of a mixture of 3-glycidoxypropyltrimethoxysilane and 3-aminopropyltrimethoxysilane,and *** long-term sta-bility of the prepared ESI emitters was demonstrated by at least 180 h of continuous *** intensity obtained by the prepared emitter was mass-flux sensitive when the flow rate was lower than 500 nL/min,while the signal in-tensity performed a concentration dependence when the flow rate was in the range of 500-800 nL/*** use-fulness of such a prepared emitter was demonstrated by the analysis of various types of samples such as organic small molecular drugs,oligosaccharide,peptide,and protein.

关键词： electrospray emitter mass spectrometry carbon-nanotube sol-gel composite material

Research on blade tip clearance cavitation and turbulent kinetic energy characteristics of axial flow pump based on the partially-averaged Navier-Stokes model

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Journal of Hydrodynamics 2024年第1期36卷 184-201页

作者： Xiao-qi Jia Shuai-kang zhang Zu-chao Zhu Key Laboratory of Fluid Transmission Technology of Zhejiang Province Zhejiang Sci-Tech UniversityHangzhou310018China

To reveal the cavitation forms of tip leakage vortex(TLV)of the axial flow pump and the flow mechanism of the flow field,this research adopts the partially-averaged Navier-Stokes(PANS)model to simulate the cavitation values of an axial flow pump,followed by experimental *** experimental result shows that compared with the shear stress transport(SST)k-ωmodel,the PANS model significantly reduces the eddy viscosity of the flow field to make the vortex structure clearer and allow the turbulence scale to be more robustly *** cavitation area within the axial flow pump mainly comprises of TLV cavitation,clearance cavitation and tip leakage flows combined effect of triangular cloud cavitation *** formation and development of cavitation are accompanied by the formation and evolution of vortex,and variations in vortex structure also generate and promote the development of *** addition,an in-depth analysis of the relationship between the turbulent kinetic energy(TKE)transport equation and cavitation patterns was also conducted,finding that the regions with relatively high TKE are mainly distributed around gas/liquid boundaries with serious cavitation and evident gas-liquid *** phenomenon is mainly attributed to the combined effect of the pressure action term,stress diffusion term and TKE production term.

关键词： Cavitation axial flow pump tip leakage vortex(TLV) partially-averaged Navier-Stokes(PANS)model turbulent kinetic energy(TKE)

Selection of female parents with high fertility and high combining abilities for cross-breeding Populus tomentosa

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Journal of Forestry Research 2019年第2期30卷 445-450页

作者： Feng-ying Bai Ning kang Ping-dong zhang Xiang-yang kang National Engineering Laboratory for Tree Breeding Beijing Advanced Innovation Center for Tree Breeding by Molecular Design Beijing Laboratory of Urban and Rural Ecological Environment Beijing Forestry University

To select maternal parents with high fertility and high combining ability during cross breeding of Populus tomentosa Carr., the ploidy level of 75 female clones was determined using flow cytometry. In addition, genetic variations and phenotypic correlations of seed traits and early growth traits, as well as the general combining ability(GCA) for seedling height(SH) and basal diameter(BD) of all diploid half-sib families were examined. A total of 26 natural triploid clones were identified. For all diploid families, family effects were significant for inflorescence length(IL), thousand kernel weight(TKW), seedling emergence rate(SER), and for SH and BD. There was a positive correlation between TKW and other traits,excluding IL. The seed-bearing coefficient(NS 9 SER)ranged from zero to 32.4%. Clones 3-10-2, 2-8, 3119,3206, and 3-10-1 had the best performance of the GCA for SH and BD. Based on the fertility and GCA for SH and BD, clone 3-10-2 and clone 3119 could be used as female parents for controlled cross-breeding of P. tomentosa.

关键词： Fertility ability General combining ability Genetic variation Half-sib family Populus tomentosa

Controlled synthesis of nanosized Si by magnesiothermic reduction from diatomite as anode material for Li-ion batteries

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International Journal of Minerals,Metallurgy and Materials 2020年第4期27卷 515-525页

作者： Li-fen Guo Shi-yun zhang Jian Xie Dong Zheng Yuan Jin kang-yan Wang da-gao Zhuang Wen-quan Zheng Xin-bing Zhao State Key Laboratory of Silicon Materials School of Materials Science and EngineeringZhejiang UniversityHangzhou 310027China Key Laboratory of Advanced Materials and Applications for Batteries of Zhejiang Province Hangzhou 310027China Hangzhou Branch Zhejiang Zotye Automobile Corporation LimitedHangzhou 310018China Shanghai Han Xing Science and Technology Co. Ltd.Shanghai 201322China

Li-ion batteries(LIBs)have demonstrated great promise in electric vehicles and hybrid electric ***,commercial graphite materials,the current predominant anodes in LIBs,have a low theoretical capacity of only 372 mAh·g?1,which cannot meet the everincreasing demand of LIBs for high energy *** Si is considered an ideal form of Si for the fabrication of LIB anodes as Si–C *** of nanoscale Si in a facile,cost-effective way,however,still poses a great *** this work,nanoscale Si was prepared by a controlled magnesiothermic reaction using diatomite as the Si *** was found that the nanoscale Si prepared under optimized conditions(800°C,10 h)can deliver a high initial specific capacity(3053 mAh·g?1 on discharge,2519 mAh·g?1 on charge)with a high first coulombic efficiency(82.5%).When using sand-milled diatomite as a precursor,the obtained nanoscale Si exhibited a well-dispersed morphology and had a higher first coulombic efficiency(85.6%).The Si–C(Si:graphite=1:7 in weight)composite using Si from the sand-milled diatomite demonstrated a high specific capacity(over 700 mAh·g?1 at 100 mA·g?1),good rate capability(587 mAh·g?1 at 500 mA·g?1),and a long cycle life(480 mAh·g?1 after 200 cycles at 500 mA·g?1).This work gives a facile method to synthesize nanoscale Si with both high capacity and high first coulombic efficiency.

关键词： silicon anode magnesiothermic reduction diatomite Li-ion batteries

New discoveries generate new questions about RNA-directed DNA methylation in Arabidopsis

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National Science Review 2017年第1期4卷 10-15页

作者： Huiming zhang Jian-kang Zhu Shanghai Center for Plant Stress Biology and CAS Center for Excellence in Molecular Plant SciencesChinese Academy of Sciences Department of Horticulture and Landscape Architecture Purdue University

Plants can establish de novo DNA methylation via the RNA-directed DNA methylation(RdDM)pathway,which involves a complex array of proteins as well as small interfering RNAs(siRNAs)and scafold *** the canonicalRd DM pathway that is best understood in Arabidopsis,complementary pairing between 24-nt siRNAs and nascent scafold RNAs,together with protein–protein interactions,recruits the protein machinery for DNA methylation.

关键词： DCL RNA DNAmethylation AGO