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Corrosion behavior of nickel-based 718 alloy determined by in situ electrochemical methods at different partial pressures of H2S in 25 wt% NaCl solution at 150℃

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Rare Metals 2019年第9期38卷 855-863页

作者： yu-bi zhang Xiao-Liang Yang An Tang School of Mechanical Engineering Henan University of EngineeringZhengzhou 451191China Chongqing Materials Research Institute Co. LtdChonging 400707China

The corrosion behavior of nickel-based 718 alloy at seven partial pressures of H2 S(PH2 S)was investigated using electrochemical impedance spectroscopy(EIS)and polarization methods in 25 wt% NaCl solution at150℃ for 168 *** tested results show that anodic reactions are controlled alternately by the diffusion mostly,then both charge transfer and diffusion and finally charge transfer mainly with the increment of PH2 *** corrosive products are composed of sulfides and oxides of Ni,Cr and Fe with double layers for PH2 S of 5.1 and 13.0 MPa and three layers for PH2 S of 10.4 MPa according to microstructures and compositions of corrosion products characterized by the scanning electron microscope(SEM)and electron probe microanalysis(EPMA)*** inner oxides layer plays a critical role in anti-corrosion in a wet H2 S environment at high temperature and pressure.

关键词： Nickel-based 718 alloy Corrosion electrochemistry Polarization Passive film

Behavior of traditional concrete dams and three-dimensional printed concrete dams under the debris flow impact

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Journal of Mountain Science 2023年第12期20卷 3703-3717页

作者： MEREE Hani YAN Shuai-xing WANG Dong-po bi yu-zhang State Key Laboratory of Geohazard Prevention and Geoenvironment Protection Chengdu University of TechnologyChengdu 610059China College of Resources and Environment Fujian Agriculture and Forestry UniversityFuzhou 350002China

This study investigated the resilience of traditional concrete dams compared to 3D printed concrete dams(3DPC)when subjected to debris *** types of dams,namely check dams,arch dams,and curve dams,were numerically analyzed using a three-dimensional Coupled Eulerian-Lagrangian(CEL)*** research focused on critical factors such as impact force and viscous energy dissipation to compare dam ***,the study examined the printing and service phases of 3DPC models,determining potential failure modes and analyzing printing *** results demonstrated that 3DPC dams outperformed traditional concrete dams,with filament deposition orientation,perpendicular to the debris flow direction,identified as a pivotal *** percentage and pattern were also found to influence the behavior of 3DPC ***,curved dams exhibited superior performance based on dam *** findings have significant potential for advancing the development of resilient dam structures capable of withstanding debris flow impacts.

关键词： Dam geometry Impact force Printing process Viscous dissipation Coupled Eulerian-Lagrangian Three-dimensional printed concrete

Feedback of Efficient Shock Acceleration on Magnetic-field Structure Inside Young Type Ia Supernova Remnants

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Research in Astronomy and Astrophysics 2024年第6期24卷 234-244页

作者： Jun-yu Shen bi-Wen Bao Li zhang Department of Astronomy Key Laboratory of Astroparticle Physics of Yunnan ProvinceYunnan UniversityKunming 650091China Key Laboratory of Statistical Modeling and Data Analysis of yunnan Province Yunnan UniversityKunming 650091China

Using an effective adiabatic index γ_(eff) to mimic the feedback of efficient shock acceleration,we simulate the temporal evolution of a young type Ia supernova remnant (SNR) with two different background magnetic field(BMF) topologies:a uniform and a turbulent *** density distribution and magnetic-field characteristics of our benchmark SNR are studied with two-dimensional cylindrical magnetohydrodynamic *** γ_(eff)is considered,we find that:(1) the two-shock structure shrinks and the downstream magnetic-field orientation is dominated by the Rayleigh–Taylor instability structures;(2) there exists more quasi-radial magnetic fields inside the shocked region;and (3) inside the intershock region,both the quasi-radial magnetic energy density and the total magnetic energy density are enhanced:in the radial direction,with γ_(eff)=1.1,they are amplified about 10–26 times more than those with γ_(eff)=5/*** in the angular direction,the total magnetic energy densities could be amplified about 350 times more than those with γ_(eff)=5/3,and there are more grid cells within the intershock region where the magnetic energy density is amplified by a factor greater than 100.

关键词： methods:numerical ISM:magnetic fields ISM:supernova remnants magnetohydrodynamics(MHD)

Investigation on the vortical structures by the Liutex method in turbulent channels at Re_(τ)=180 with scalloped and triangular riblet control

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Journal of Hydrodynamics 2024年第1期36卷 35-52页

作者： zhang-dan yu Shang Jiang Hai-dong yu bi-yu Pang Xin Dong Yi-qian Wang School of Mathematical Sciences Soochow UniversitySuzhou215006China Beijing Institute of Astronautical System Engineering Beijing100076China

Riblets are a series of small protrusions formed along the flow direction,which have been extensively studied as a passive turbulent drag reduction *** and numerical simulations have shown that well-designed riblets can significantly reduce drag in turbulent flows,making them highly promising and valuable for various *** this study,we focus on a scalloped riblet,which is designed by smoothly connecting two third-order polynomials,and thus the sharpness of the tip and the curvature of the valley can be well *** conduct direct numerical simulations of turbulent channel with smooth plate,scalloped riblet-mounted and triangular riblet-mounted *** in wall units of W^(+)=20 and height-width ratio ofγ=0.5 are selected for both riblet *** with the smooth plate case,the scalloped riblet case achieves an 8.68%drag reduction,while the triangular riblet case achieves a 4.79%drag *** obtained drag reduction rate of the triangular riblet is consistent with previous experiments and simulations,and the results indicate that the scalloped riblet is more effective in reducing drag and deserves further *** compare turbulent statistics of the scalloped riblet case with those of the triangular riblet *** mean velocity profiles of riblets are similar,but both the Reynolds shear stress and second-order statistics of velocity fluctuations and Liutex are significantly reduced in the scalloped riblets controlled turbulent channel,indicating that the scalloped riblet can more effectively suppress the spanwise and wall-normal turbulent intensity near the *** also compare the pre-multiplied spectra of streamwise velocity and streamwise Liutex component for the three cases to investigate the energy distribution and characteristics of Liutex *** Liutex vortex identification method is also utilized to analyze the instantaneous flow field,which provides insights into the flow field and could be bene

关键词： Liutex vector riblet drag reduction tip sharpness turbulent channel scalloped

Optimal array layout of cylindrical baffles to reduce energy of rock avalanche

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Journal of Mountain Science 2022年第2期19卷 493-512页

作者： bi yu-zhang WANG Dong-po FU Xian-lei LIN Yi-xiong SUN Xin-po JIANG Zhe-yuan B-Z geotechnical Company Nanjing 210096China State Key Laboratory of Geohazard Prevention and Geoenvironment Protection Chengdu University of TechnologyChengdu 610059China College of Civil Engineering Sichuan University of Science and EngineeringZigong 643000China Jiangsu Key Laboratory of Urban Underground Engineering&Environmental Safety Institute of Geotechnical EngineeringSoutheast UniversityNanjing 210096China

The array of baffles protection structure is a flow resistance structure with good drainage,blocking,and intercepting effects on the rock *** this research,the physical model test on rock avalanches was *** parameters(column spacing,row spacing,and a number of baffles)were used as indicators to determine the optimal layout of the array of baffles for energy efficiency consumption ***,the lattice Boltzmann numerical simulation method was used to build a numerical simulation model of rock avalanches-array of the baffles-hazard-bearing body to obtain the rock’s velocity attenuation and flow trajectory avalanches in the impact baffle protection ***,the results of the physical model test and the numerical simulation were mutually *** following conclusions were drawn through two methods of physical model test and numerical simulation.(1)The optimal layout parameters of array of baffles were determined as three rows of array of baffles(The number of baffles in each row is 7,8,9),column spacing Sc=3.5,and row spacing Sr=4.5.(2)Under the conditions of high baffle density(such as Sc=1.5,2.5),the rock avalanches would produce a certain degree of circumfluence,which would increase the fluid velocity by at least 24.5% over the average velocity,so the column spacing density should be increased appropriately to achieve the optimal effect of reducing the energy of rock avalanches.(3)In the event of a prototype grooved rock avalanches with a velocity close to 24.5 m/s and a flow depth of about 1.5 m,the three-row array of baffles protection with the parameters Sc^(*)=1.18 m and Sr^(*)=1.51 m could be arranged,playing the role of optimizing the array of baffles to guide the flow and block the energy *** experiments can be used to replace laboratory experiments to some *** Lattice Boltzmann method-Discrete element method(LBM-DEM)studies are required before applications to practical engineering.

关键词： Lattice Boltzmann Physical model Numerical simulation Energy consumption optimization

A new method of calculating crown projection area and its comparative accuracy with conventional calculations for asymmetric tree crowns

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Journal of Forestry Research 2024年第4期35卷 171-188页

作者： Mingrui zhang Huiquan bi Xingji Jin Michael McLean School of Forestry Northeast Forestry UniversityHarbin 150040People’s Republic of China Forest Science NSW Department of Primary IndustriesLevel 304PSQ12 Darcy StreetParramattaNSW 2150Australia School of Ecosystem and Forest Sciences The University of MelbourneMelbourne 3010Australia

This paper introduces a new method of calculating crown projection area(CPA),the area of level ground covered by a vertical projection of a tree crown from measured crown radii through numerical interpolation and *** novel method and other four existing methods of calculating CPA were compared using detailed crown radius measurements from 30 tall trees of Eucalyptus pilularis variable in crown size,shape,and *** four existing methods included the polygonal approach and three ways of calculating CPA as the area of a circle using the arithmetic,geometric and quadratic mean *** were made across a sequence of eight non-consecutive numbers(from 2 to 16)of measured crown radii for each tree over the range of crown asymmetry of the 30 trees through generalized linear models and multiple comparisons of *** sequence covered the range of the number of crown radii measured for calculating the CPA of a tree in the literature.A crown asymmetry index within the unit interval was calculated for each tree to serve as a normative *** a slight overestimation of 2.2%on average and an overall mean error size of 7.9%across the numbers of crown radii that were compared,our new method was the least biased and most *** CPA as a circle using the quadratic mean crown radius was the second best,which had an average overestimation of 4.5%and overall mean error size of 8.8%.These two methods remained by and large unbiased as crown asymmetry increased,while the other three methods showed larger bias of *** the conventional method of using the arithmetic mean crown radius to calculate CPA as a circle,bias correction factors were developed as a function of crown asymmetry index to delineate the increasing magnitude of bias associated with greater degrees of crown *** study reveals and demonstrates such relationships between the accuracy of CPA calculations and crown asymmetry and will help increase awa

关键词： Crown radius measurements Interpolated crown contour Projected crown area Multiple comparisons of means

Manipulating Nb-doped SrFeO_(3−δ)with excellent performance for proton-conducting solid oxide fuel cells

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Journal of Advanced Ceramics 2024年第5期13卷 579-589页

作者： Hailu Dai Hongzhe Du Samir Boulfrad Shoufu yu Lei bi Qinfang zhang School of Materials Science and Engineering Yancheng Institute of TechnologyYancheng 224051China College of Science&Engineering Hamad Bin Khalifa UniversityDoha 34110Qatar School of Resource Environment and Safety Engineering University of South ChinaHengyang 421001China

Nb-doped SrFeO_(3−δ)(SFO)is used as a cathode in proton-conducting solid oxide fuel cells(H-SOFCs).First-principles calculations show that the SrFe0.9Nb0.1O_(3−δ)(SFNO)cathode has a lower energy barrier in the cathode reaction for H-SOFCs than the Nb-free SrFeO_(3−δ)*** experimental studies show that Nb doping substantially enhances the performance of the SrFeO_(3−δ)***,oxygen vacancies(VO)were introduced into SFNO using the microwave sintering method,further improving the performance of the SFNO *** mechanism behind the performance improvement owing to VO was revealed using first-principles calculations,with further optimization of the SFNO cathode achieved by developing a suitable wet chemical synthesis route to prepare nanosized SFNO *** method significantly reduces the grain size of SFNO compared with the conventional solid-state reaction method,although the solid-state reaction method is generally used for preparing Nb-containing *** a result of defect engineering and synthesis approaches,the SFNO cathode achieved an attractive fuel cell performance,attaining an output of 1764 mW·cm−2 at 700℃ and operating for more than 200 *** manipulation of Nb-doped SrFeO_(3−δ)can be seen as a“one stone,two birds”strategy,enhancing cathode performance while retaining good stability,thus providing an interesting approach for constructing high-performance cathodes for H-SOFCs.

关键词： SrFeO_(3−δ)-(SFO) cathode proton conductor solid oxide fuel cells(SOFCs)

Facilitating prelithiation of silicon carbon anode by localized high-concentration electrolyte for high-rate and long-cycle lithium storage

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Carbon Energy 2024年第6期6卷 216-233页

作者： yuanxing zhang Borong Wu Jiaying bi Xinyu zhang Daobin Mu Xin-yu zhang Ling zhang Yao Xiao Feng Wu School of Materials Science and Engineering Beijing Institute of TechnologyBeijingChina Chongqing Innovation Center Beijing Institute of TechnologyChongqingChina College of New Energy Xi′an Shiyou UniversityXi′anChina Institute for Carbon Neutralization College of Chemistry and Materials EngineeringWenzhou UniversityWenzhouChina Key Laboratory of Advanced Energy Materials Chemistry(Ministry of Education) Nankai UniversityTianjinChina

The commercialization of silicon-based anodes is affected by their low initial Coulombic efficiency(ICE)and capacity decay,which are attributed to the formation of an unstable solid electrolyte interface(SEI)***,a feasible and cost-effective prelithiation method under a localized highconcentration electrolyte system(LHCE)for the silicon-silica/graphite(Si-SiO_(2)/C@G)anode is designed for stabilizing the SEI layer and enhancing the *** thin SiO_(2)/C layers with-NH_(2) groups covered on nano-Si surfaces are demonstrated to be beneficial to the prelithiation process by density functional theory calculations and electrochemical *** SEI formed under LHCE is proven to be rich in ionic conductivity,inorganic substances,and flexible organic ***,faster Li+transportation across the SEI further enhances the prelithiation effect and the rate performance of Si-SiO_(2)/C@G *** also leads to uniform decomposition and high stability of the SEI with abundant organic *** a result,the prepared anode shows a high reversible specific capacity of 937.5 mAh g^(-1)after 400 cycles at a current density of 1 *** 811‖Li-SSGLHCE full cell achieves a high-capacity retention of 126.15 mAh g^(-1)at 1 C over 750 cycles with 84.82%ICE,indicating the great value of this strategy for Si-based anodes in large-scale applications.

关键词： localized high-concentration electrolytes prelithiation SEI layer silicon anode

Numerical investigation of effects of “baffles-deceleration strip” hybrid system on rock avalanches

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Journal of Mountain Science 2019年第2期16卷 414-427页

作者： bi yu-zhang HE Si-ming DU Yan-jun SHAN Jie YAN Shuai-xing WANG Dong-po SUN Xin-po Institute of Geotechnical Engineering of Southeast University School of Transportation Southeast University Key Laboratory of Mountain Hazards and Surface Process Chinese Academy of Sciences Institute of Mountain Hazards and Environment Chinese Academy of Sciences Chinese Academy of Sciences Center for Excellence in Tibet Plateau Earth Sciences University of Chinese Academy of Sciences State Key Laboratory of Geohazard Prevention and Geoenvironment Protection Chengdu University of Technology College of civil engineering Sichuan University of Science and Engineering

Arrays of baffles are usually installed in front of protection site to attenuate the flow energy of rock avalanches in mountainous areas. Optimization design is crucial for efficiency promotion in hazard energy dissipation engineering. In this study, a deceleration strip was added in the baffles protection system to optimize the traditional baffles system. The effects of the "baffles-deceleration strip" hybrid protection system was discussed in detail with the nails number and nails angle. This study presents details of numerical experiments using the discreteelement method(DEM). The effect of the optimization of hybrid protection system(nail angle and nail number) were investigated specifically, especially the impact force that avalanches exerted on structures. The results show that the maximum impact forces and kinetic energy of the rock avalanches decreases with the increase of the number and angle of the nail. Moreover, the distance between the toe and the bearing structure(L_m) is also a key factor. The shorter the distance L_m(30 m) is, the higher the maximum impact force are. The longer the distance L_m(70 m) is, the lower the maximum impact force are. Under the same size of the nails, increasing the numbers can enhance the dissipation ability of the hybrid protection system. Meanwhile, increasing itsangle can also enhance the dissipation ability. There are three key ways for nails attenuate rock avalanches:(i) block the fine particles directly;(ii) form the particles bridge between nails and baffles;(iii) dissipate the coarse particles energy directly. The effect of segregation in rock avalanches is crucial for the energy dissipation mechanism, which is a key factor to optimize the traditional baffle system.

关键词： Rock avalanches Baffles Hybrid system Energy dissipation Impact force