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Enhanced memristor performance via coupling effect of oxygen vacancy and ferroelectric polarization

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Journal of Materials Science & Technology 2024年第4期171卷 139-146页

作者： zhi yun Yue zhi Dong Zhang Zhan Jie Wang Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering University of Science and Technology of ChinaShenyang 110016China School of Materials Science and Engineering Shenyang University of TechnologyShenyang 110870China

As a new type of nonvolatile memory,the resistive memristor has broad application prospects in in-formation storage and neural computing based on its excellent resistive switching(RS)*** present,it is still a great challenge to improve both ferroelectric polarization and leakage current to achieve a high RS on/offratio of ferroelectric ***,epitaxial Pb(Zr_(0.40)Ti_(0.60))O_(3)(PZT)thin films with low content Ca doping were deposited on the Nb:SrTiO_(3)substrate to prepare PCZT/NSTO het-erostructures and their RS behaviors were *** research findings show that compared with pure PZT film,the ferroelectric polarization of 1-mol%-Ca-doped PZT film is slightly improved,while the leak-age current is increased by three orders of ***,the RS on/offratio reaches 2.5×10^(5),about three orders of magnitude higher than pure PZT *** theoretical analysis reveals that the RS behavior of PCZT/NSTO heterostructures is controlled by the PCZT/NSTO interfacial barrier and the space charge-limited current *** results demonstrate that the ferroelectricity and electricity of ferroelectric thin films can be improved simultaneously by doping low-content Ca ions to increase the RS performance,which provides a good reference for the development of high-performance ferroelectric memristor devices.

关键词： Ferroelectric memristor Ca-doped PZT Ferroelectric polarization Oxygen vacancies Resistive switching

Numerical study on roll dynamics of damaged ship in beam waves and calm water

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Journal of Hydrodynamics 2023年第3期35卷 482-497页

作者： zhi-yun Huang zhi-liang Gao Sang-ming Xu Key Laboratory of High Performance Ship Technology Ministry of Education Wuhan University of TechnologyWuhan 430063China Wuhan University of Technology College of Marine and Energy Power EngineeringWuhan 430063China Union Strong(Beijing)Technology Co. LtdBeijing 100176China

Computational fluid dynamics is used to study the roll dynamics of a damaged ship in beam waves with various steepnesses and in calm *** wave-making method,which combines the velocity-inlet boundary and momentum source with the fifth-order Stokes theory,is employed for wave *** SST k-ωturbulence model with a modification to the turbulent viscosity in Reynolds stress is adopted to prevent the over-production of turbulence in the numerical wave *** lateral drift restrained model with a combined dynamic mesh strategy is utilized to deal with the coupled heave-sway-roll motions of the ***,benchmarking tests are performed,including wave generation and roll response of the damaged ship in regular beam ***,the effects of incident wave steepness on the roll response of the damaged ship are *** different wave steepnesses,the ship roll motion is dominated by the first-order harmonic *** second-order component increases with the increase of wave ***,the roll hydrodynamic coefficients for different parts of the damaged ship are investigated with different rolling *** added moment of inertia for the whole damaged ship is mainly attributed to the external hull composition and changes slightly with the change of roll amplitude and *** added moment of inertia for the compartments could be negative in particular *** damping coefficients of the whole damaged ship and external hull increase with the increase of roll amplitude and frequency,while that of the compartments appears complicated with the change of roll amplitude and frequency.

关键词： Damaged ship roll dynamics wave steepness hydrodynamic coefficients computational fluid dynamics(CFD)

Heat engines of the Kerr-AdS black hole

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Communications in Theoretical Physics 2023年第12期75卷 129-137页

作者： Yi Zhong yun-zhi Du School of Physics and Electronics Hunan UniversityChangsha 410082China Department of Physics Shanxi Datong UniversityDatong 037009China Institute of Theoretical Physics Shanxi Datong UniversityDatong 037009China

In this paper,we investigate three types of heat engines for the rotating Kerr-Anti de Sitter(Kerr-AdS)black *** first briefly review the thermodynamics and phase structure of the Kerr-AdS black hole and obtain the phase structure in the T-S *** thermal stability of Kerr-AdS black holes,along with their dependence on various parameters,is thoroughly ***,by utilizing the phase diagram,we consider three types of heat engines:the maximal Carnot engine,Stirling engine,and Rankine *** calculate both the work and efficiency for these *** results indicate that angular momentum has a significant influence on these heat engines.

关键词： black hole heat engine Kerr-AdS

Modification of methyl oleate for silicon-based biological lubricating base oil

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Chinese Journal of Chemical Engineering 2017年第1期25卷 130-136页

作者： Shixing Cui zhi yun Xia Gui College of Chemistry and Chemical Engineering Nanjing University of Technology Nanjing 210009 China

A new kind of silicon-based biological lubricating base oil with good viscosity-temperature behavior,viscosity index,thermostability,oxidation stability and wear resistance performance was synthesized as a derivative of methyl *** reaction was introduced to further improve methyl oleate oxidation stability and lubricity after epoxidation and open-ring *** order of effectiveness of acid binding agent was N,N-diisopropylethylamine(DIEA) > pyridine > diethylamine > triethylamine,and the effects of various parameters on the trimethylsilylation reaction as well as on the silicon-oxygen bond stability and reaction yield were studied.A maximum yield of 34.54%was achieved at hydroxyl/trimethyl chlorosilane/DIEA molar ratio of1:1.25:1,reaction temperature 40℃,reaction time 1.5 h.

关键词： Methyl oleate Trimethyl chlorosilane Acid binding agent N N-diisopropylethylamine Lubricity Silicon-based biological lubricating base oil

Continuous production of biodiesel from cottonseed oil and methanol using a column reactor packed with calcined sodium silicate base catalyst

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Chinese Journal of Chemical Engineering 2016年第4期24卷 499-505页

作者： Xia Gui Sichen Chen zhi yun College of Chemistry and Chemical Engineering Nanjing Tech University

Sodium silicate and that calcined at 400℃ for 2 h were used to catalyze the transesterification of cottonseed oil with methanol. Calcined sodium silicate （CSS） catalyst exhibited much higher catalytic activity and stability. A maximum biodiesel yield of 98.9~ was achieved at methanol/oil mole ratio of 12：1, reaction temperature 65℃, reaction time 3.0 h, and CSS/oil mass ratio of 2 Wffo. After 7 consecutive reactions without any treatment, biodiesel yield reduced to 82.5%. Considering technological and economic feasibility, CSS base catalyst supported on 0 rings was prepared for continuous transesterification. The maximum yield was 99.1% under optimum conditions （reaction temperature 55 ~C, methanol velocity 1 ml. rain- 1, oil velocity 3 ml- rain- 1, and 5 tower sec- tions）. These results indicate that this new continuous biodiesel production process and apparatus present a great potential for industrial application in biodiesel.

关键词： TransesterificationCottonseed oilCalcined sodium silicateBiodieselSodium silicateContinuous production

Payne Effect and Weak Overshoot in Rubber Nanocomposites

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Chinese Journal of Polymer Science 2022年第1期40卷 85-92页

作者： zhi-yun Li Yi-Hu Song Qiang Zheng MOE Key Laboratory of Macromolecular Synthesis and Functionalization Department of Polymer Science and EngineeringZhejiang UniversityHangzhou 310027China

Payne effect and its associated weak overshoot are of importance for understanding and regulating the softening of rubber nanocomposites under large amplitude ***,Payne effect in diverse filled vulcanizates is investigated for generalizing the common *** curves of strain amplitude dependent storage modulus are created with respect to microscopic strain amplitude of the matrix,revealing a matrix-dominated elastic nonlinearity being independent of type and dispersity of filler,crosslinking density and sol fraction of matrix and filler-rubber interfacial ***,carbonaceous fillers with higher affinity to the rubber matrices yield lower strain amplification and higher overshoot behavior in comparison with siliceous *** investigation would be illuminating for preparing rubber nanocomposites with optimized reinforcement and softening performances.

关键词： Vulcanizate nanocomposites Payne effect Weak overshoot

Mutation on Knots and Whitney's 2-Isomorphism Theorem

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Acta Mathematica Sinica,English Series 2013年第6期29卷 1219-1230页

作者： zhi yun CHENG Hong Zhu GAO School of Mathematical Sciences Beijing Normal UniversityLaboratory of Mathematicsand Complex SystemsMinistry of Education

Whitney＇s 2-switching theorem states that any two embeddings of a 2-connected planar graph in S2 can be connected via a sequence of simple operations, named 2-switching. In this paper, we obtain two operations on planar graphs from the view point of knot theory, which we will term ＂twisting＂ and ＂2-switching＂ respectively. With the twisting operation, we give a pure geometrical proof of Whitney＇s 2-switching theorem. As an application, we obtain some relationships between two knots which correspond to the same signed planar graph. Besides, we also give a necessary and sufficient condition to test whether a pair of reduced alternating diagrams are mutants of each other by their signed planar graphs.

关键词： Planar graph twisting 2-switching mutation

Solubilities of CO2 in some glycol ethers under high pressure by experimental determination and correlation

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Chinese Journal of Chemical Engineering 2016年第3期24卷 373-378页

作者： Wei Wang zhi yun zhigang Tang Xia Gui College of Chemistry and Chemical Engineering Nanjing University of TechnologyNanjing 210009China State Key Laboratory of Chemical Engineering Department of Chemical Engineering Tsinghua UniversityBeijing 100084China

The binary vapor–liquid equilibrium data of CO_2 in diethylene glycol(monomethyl,monoethyl,monobutyl,dimethyl,diethyl,dibutyl)ether were determined from 288.15 to 318.15 K at pressure up to 6 MPa based on the constant-volume *** was found by contrast that the ether group in solvents can promote the CO_2 absorption,but the hydroxyl group will inhibit the CO_2 ***,the solubilities of CO_2 showed an upward trend with the increasing molecular lengths of *** experimental data were also correlated with a modified Patel–Teja equation of state(PT EOS)combined with the traditional van der Waals one-fluid mixing rules and the results showed a satisfactory agreement between the model and the experimental data.

关键词： Vapor-liquid equilibrium CO2D iethylene glycol ethers PT EOS

Topology of charged AdS black hole in restricted phase space

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Chinese Physics C 2024年第9期48卷 291-299页

作者： Han Wang yun-zhi Du College of Mathematics and Statistics Shanxi Datong UniversityDatong 037009China Department of Physics Shanxi Datong UniversityDatong 037009China Institute of Theoretical Physics Shanxi Datong UniversityDatong 037009China

The local topological properties of black hole systems can be expressed through winding numbers as *** date,AdS black hole thermodynamics are often depicted by the dual parameters of(T,S),(P,V),(Φ,Q) in the extended phase space,while there have been several studies on the black hole thermodynamics in the restricted phase *** this paper,we analyze the topological properties of charged AdS black holes in the restricted phase space under the higher-dimension and higher-order curvature gravity *** results show that the topological number of the charged black hole in the same canonical ensembles is a constant and is independent of the concrete dual thermodynamical ***,the topological number in the grand canonical ensemble is different from that in the canonical ensemble for the same black hole ***,these results are independent of dimension d and highe st order k of the Lanczos-Lovelock densities.

关键词： topology phase transition black hole