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Improving the water electrolysis performance by manipulating the generated nano/micro-bubbles using surfactants

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Nano Research 2023年第1期16卷 420-426页

作者： Houpeng Wang Zhaoxiang Xu wei Lin Xue Yang Xianrui Gu wei zhu Zhongbin zhuang SINOPEC Research Institute of Petroleum Processing Beijing 100083China State Key Lab of Organic-Inorganic Composites and Beijing Advanced Innovation Center for Soft Matter Science and Engineering Beijing University of Chemical TechnologyBeijing 100029China Beijing Key Laboratory of Energy Environmental Catalysis Beijing University of Chemical TechnologyBeijing 100029China

The impeded mass transfer rate by on-site-generated gas bubbles at both cathode and anode dramatically reduces the energy conversion efficiency of the proton exchange membrane water electrolyzer(PEMWE).Herein,we report a surfactant-assistant method to accelerate the nano/micro-bubble detachment and the mass transfer rate by reducing the surface tension,resulting in an increase in overall *** kinds of surfactants are studied in this *** potassium perfluorobutyl sulfonate(PPFBS),which has the structural similarity to Nafion,shows a significant promotion of activity and stability for both hygrogen evolution reaction(HER)and oxygen evolution reaction(OER)in the acidic medium at the high current density *** HER overpotential at 0.1 A·cm−2 decreased 22%,and the current density at−0.4 V increased 31%by adding *** promotion of overall efficiency by PPFBS on a homemade PEMWE was also *** reduced surface tension and electrostatic repulsion were the probable origins of the accelerated bubble detachment.

关键词： proton exchange membrane water electrolysis bubble overpotential surfactant electrostatic repulsion

Neutron Diffraction Study of Low-Cycle Fatigue Behavior in an Austenitic–Ferritic Stainless Steel

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Acta Metallurgica Sinica(English Letters) 2015年第10期28卷 1247-1256页

作者： Ming-wei zhu Nan Jia Feng Shi Bjorn Clausen School of Materials Science and Engineering Shenyang Aerospace University Key Laboratory for Anisotropy and Texture of Materials(ATM) Northeastern University School of Science Northeastern University Los Alamos National Laboratory Los Alamos Neutron Science Center

By performing in situ neutron diffraction experiments on an austenitic-ferritic stainless steel subjected to lowcycle fatigue loading, the deformation heterogeneity of the material at microscopic level has been revealed. Based on the in situ neutron diffraction data collected from a single specimen together with the mechanical properties learned from the ex situ micro-hardness, a correlation has been found. The performance versus diffraction-profile correlation agrees with the cyclic-deformation-induced dislocation evolution characterized by ex situ TEM observation. Moreover, based on the refined neutron diffraction-profile data, evident strain anisotropy is found in the austenite. The high anisotropy in this phase is induced by the increase in dislocation density and hence contributes to the hardening of the steel at the first 10 *** 10 fatigue cycles, the annihilation and the rearrangement of the dislocations in both austenitic and ferritic phases softens the plastically deformed specimen. The study suggests that the evolution of strain anisotropy among the differently oriented grains and micro-strain induced by lattice distortion in the respective phases mostly affect the cyclic-deformationinduced mechanical behavior of the steel at different stages of fatigue cycles. The stress discrepancy between phases is not the dominant mechanism for the deformation of the steel.

关键词： Duplex steel Neutron diffraction Fatigue Plastic deformation Microstructure

Revisiting pulsar velocities using Gaia Data Release 2

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Research in Astronomy and Astrophysics 2021年第6期21卷 294-300页

作者： Meng Yang Shi Dai Di Li Chao-wei Tsai wei-wei zhu Jie Zhang China West Normal University Nanchong 637000China National Astronomical Observatories Chinese Academy of SciencesBeijing 100101China School of Science Western Sydney UniversityLocked Bag 1797Penrith NSW 2751Australia CSIRO Astronomy and Space Science Australia Telescope National FacilityPO Box 76EppingNSW 1710Australia University of Chinese Academy of Sciences Beijing 100049China NAOC-UKZN Computational Astrophysics Centre University of KwaZulu-NatalDurban 4000South Africa Qilu Normal University Zhangqiu 250200China

Precise measurements of neutron star(NS)velocities provide critical clues in regard to the supernova physics and evolution of binary *** on Gaia Data Release 2(DR2),we selected a sample of 24 young(<3 Myr)pulsars with precise parallax measurements and measured the velocity of their local standard of rest(LSR)and the velocity dispersion among their respective local stellar *** median velocity difference between thus calculated LSRs and the Galactic rotation model is~7.6 km s^(-1),small compared to the typical velocity dispersion of~27.5 km s^(-1).For pulsars off the Galactic plane,such differences grow significantly to as large as~40 km s^(-1).More importantly,the velocity dispersion of stars in the local group of low-velocity pulsars can be comparable to their transverse velocities,suggesting that the intrinsic velocities of NS progenitors should be taken into account when we consider their natal kicks and binary *** also examined the double NS system J0737-3039 A/B,and measured its transverse velocity to be 26-13+18 km s^(-1)assuming nearby Gaia sources are representative of their birth *** work demonstrated the feasibility and importance of using Gaia data to study the velocity of individual systems and velocity distribution of NSs.

关键词： (stars:) pulsars:general

Highly luminescent and stable CsPbBr3 perovskite quantum dots modified by phosphine ligands

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Nano Research 2019年第4期12卷 785-789页

作者： Yan Li Xiaoyan Wang weinan Xue wei Wang wei zhu Lianjing Zhao Key Laboratory far Advanced Materials Shanghai Key Laboratory of Functional Materials Chemistry School of Chemistry and Molecular Engineering East China University of Science and Technology Shanghai 200237 China

All-inorganic cesium lead halide perovskite quantum dots (QDs) have been a promising candidate for optoelectronic devices in recent years,such as light-emitting diodes,photodetectors and solar cells,owing to their superb optoelectronic ***,the stability issue of nanocrystals is a bottleneck for their practical ***,we report a facile method for the synthesis of a series of phosphine ligand modified CsPbBr3 QDs with high PL *** introducing organic phosphine ligands,the tolerance of CsPbBr3 QDs to ethanol,water and UV light was dramatically ***,the phosphine ligand modified QD films deposited on the glass subtracts exhibit superior PL intensity and optical stability to those of pristine QD based films.

关键词： perovskite quantum dots organic phosphine ligands optical and structure stability

ASYMPTOTIC EFFICIENT ESTIMATION IN SEMIPARAMETRIC NONLINEAR REGRESSION MODELS

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Applied Mathematics(A Journal of Chinese Universities) 1999年第1期14卷 57-66页

作者： zhu Zhongyi\ wei Bocheng Dept. of Appl. Math. Southeast Univ. Nanjing

Abstract In this paper, the estimation method based on the “generalized profile likelihood” for the conditionally parametric models in the paper given by Severini and Wong (1992) is extended to fixed design semiparametric nonlinear regression *** these semiparametric nonlinear regression models,the resulting estimator of parametric component of the model is shown to be asymptotically efficient and the strong convergence rate of nonparametric component is *** results (for example Chen (1988),Gao & Zhao (1993), Rice (1986) et al.) are extended to fixed design semiparametric nonlinear regression models.

关键词： 1991 MR Subject Classification 62G07 62F35

Extra low friction coefficient caused by the formation of a solid-like layer:A new lubrication mechanism found through molecular simulation of the lubrication of MoS_2 nanoslits

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Chinese Journal of Chemical Engineering 2018年第12期26卷 2412-2419页

作者： Jiahui Li Yudan zhu Yumeng Zhang Qingwei Gao wei zhu Xiaohua Lu Yijun Shi College of Chemical Engineering State Key Laboratory of Materials-oriented Chemical Engineering Nanjing Tech University Energy Engineering Division of Energy Science Lule? University of Technology Division of Machine Elements Lule? University of Technology

Monolayer molybdenum disulfide(MoS2) is a novel two-dimensional material that exhibits potential application in lubrication technology. In this work, molecular dynamics was used to investigate the lubrication behaviour of different polar fluid molecules(i.e., water, methanol and decane) confined in monolayer Mo S2 nanoslits. The pore width effect(i.e., 1.2, 1.6 and 2.0 nm) was also evaluated. Results revealed that decane molecules exhibited good lubricating performance compared to the other two kinds of molecules. The friction coefficient followed the order of decane b methanol b water, and decreased evidently as the slit width increased, except for decane. Analysis of the spatial distribution and mobility of different confined fluid molecules showed that a solid-like layer was formed near the slit wall. This phenomenon led to the extra low friction coefficient of confined decane molecules.

关键词： Molecular dynamics simulation Microstructure Molybdenum disulfide Residence time distribution

Modeling of turbidity dynamics caused by wind-induced waves and current in the Taihu Lake

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International Journal of Sediment Research 2013年第2期28卷 139-148页

作者： Ting-feng WU Bo-qiang QIN Guang-wei zhu Meng-yuan zhu wei LI Cheng-mei LUAN State Key Laboratory of Lake Science and Environment Nanjing Institute of Geography and LimnologyChinese Academy of Sciences Jiangsu Province Hydrology and Water Resource Investigation Bureau

A simple turbidity model was developed with a sound physical basis based on in situ high-frequency observations of short-term,strong wind-induced sediment suspension in Taihu Lake,*** validation results show that the model could successfully simulate turbidity caused by strong wind events,despite the relatively poor simulation accuracy for high values of turbidity caused by the entrainment of cyanobacteria by turbulence. The in situ observations and model simulation results indicate that the wind waves were within a narrow spectral band,with spectral energy mainly distributed within the 0.28-0.75 Hz band on opposite sides of the peak *** high-frequency and low-energy wind waves are sensitive to depth ***,the average depth of the lake is only 1.9 m,and wind waves still represent the main force of sediment suspension at the sediment-water ***,lake currents were of significance to the maintenance of background turbidity in calm waves or ripples and in the determination of critical shear *** considering the spatial distribution of hydrodynamics and sediment,the model can be used to simulate the turbidity of the entire lake as well as boundary conditions for three-dimensional numerical models.

关键词： Taihu Lake Wind-driven current Wind wave frequency spectrum Turbidity Critical shear stress Model

Optimal design of 6-DOF vibration isolation platform based on transfer matrix method for multibody systems

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Acta Mechanica Sinica 2021年第1期37卷 127-137,I0004页

作者： Min Jiang Xiaoting Rui wei zhu Fufeng Yang Yanni Zhang Institute of Launch Dynamics Nanjing University of Science and TechnologyNanjing210094China

The structure parameters of 6-degree of freedom(DOF)vibration isolation platform have a significant effect on its *** make the designed vibration isolation platform perform well,non-dominanted sorting genetic algorithm version II(NSGA-II)was applied to optimize its structure based on the transfer matrix method for multibody ***,the Jacobian matrix of 6-DOF vibration isolation platform was solved based on ***,the transfer equation of 6-DOF vibration isolation system was established by the linear transfer matrix method for multibody *** the formula of its natural frequency was derived according to the boundary conditions of the ***,the manipulability index was constructed based on a dimensionless Jacobian *** a new performance index function was established considering the influence of dynamic isotropic and legs ***,genetic algorithm(GA)and NSGA-II were used to optimize the structure of the 6-DOF vibration isolation platform under the same conditions,*** showed that NSGA-II had higher optimization efficiency,better calculation accuracy and shorter optimization time than that of ***,NSGA-II was adopted for multi-objective optimization design of 6-DOF vibration isolation platform based on the constraint *** Pareto solutions were obtained,which provides structural parameters for subsequent design ***,the proposed optimization method and the performance index in this paper provide a theoretical basis for the optimal design of relevant vibration isolation mechanism.

关键词： Optimal design 6-DOF vibration isolation Transfer matrix method Non-dominanted sorting genetic algorithm version II(NSGA-II)

Structural Optimization of Electromagnetic Swirling Flow in Nozzle of Slab Continuous Casting

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Acta Metallurgica Sinica(English Letters) 2018年第12期31卷 1317-1326页

作者： Xiao-wei zhu De-wei Li Chun-Lei Wu Katsukiyo Marukawa Qiang Wang Key Laboratory of Electromagnetic Processing of Materials(Ministry of Education) Northeastern University School of Metallurgy Northeastern University School of Resources and Materials Northeastern University at Qinhuangdao

During the slab continuous casting process, the flow field of molten steel in the mold plays a decisive role in the quality ofthe slab. In this paper, electromagnetic swirling flow in nozzle technology is proposed to control the flow field in *** technology can drive molten steel to rotate inside the submerged entry nozzle by electromagnetic force, therebycontrolling the flow field. This research shows that it can reduce the impact of molten steel on the bottom of nozzle andpartly reduce the negative pressure at the upper part of nozzle outlet which is even eliminated by optimizing the structureand angle of nozzle. The area of heat flux of the mold wall becomes larger, and the crest value of heat flux gets lower thanthat without swirling in nozzle and any nozzle optimization. The meniscus fluctuates smoothly, and the flow velocity at thetop surface is within a reasonable range. The temperature field distribution in the mold is uniform which was beneficial tothe growth of equiaxed crystal and decreased element segregation.

关键词： Continuous casting Submerged entry nozzle Electromagnetic swirling flow Slab Numerical simulation