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Influence of Finish Rolling Temperature on Microstructure and Mechanical Properties of a 19Cr1.5Mo0.5W Ferritic Stainless Steel

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Acta Metallurgica Sinica(english Letters) 2020年第7期33卷 991-1000页

作者： Hou-Long liu ling-ling liu Ming-Yu Ma li-Qing Chen State Key Laboratory of Rolling and Automation Northeastern UniversityShenyang 110819China

A 444-type heat-resistant ferritic stainless steel containing 0.05 wt% Ce(rare earth element) and 2 wt%(Mo+W) was adopted as an experimental material to study the effect of finish rolling temperature on microstructure and texture evolution as well as on mechanical properties and *** rolling processes contain hot rolling at two different finish rolling temperatures(860℃ and 770℃) and annealing,cold rolling and subsequent *** was found that the microstructures after hot rolling and annealing could be refined by lowering finish rolling *** resultant microstructures after cold rolling and annealing were hereditarily *** finish rolling temperature can weaken α-fiber texture in hotrolled or cold-rolled ferritic stainless steel strip,while γ-fiber texture in the final product was homogeneously ***,enhanced mechanical property and formability in terms of strength and average plastic strain ratio could be obtained via decreasing finish rolling temperature.

关键词： steel Microstructure microstructure

Aerodynamic adjoint optimization of turbomachinery with direct control on blade design parameters

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Chinese Journal of Aeronautics 2023年第11期36卷 119-134页

Nowadays,the adjoint method has become a popular approach in the optimization of turbomachinery to further improve its aerodynamic ***,design variables in these adjoint optimization applications are generally not direct design parameters of blade(such as wedge angles or maximum thickness),making the geometric variation by adjoint optimization can hardly be re-extracted as the change of each design *** giving considerations to the G1 continuity constraint of adjoint method on its parameterization method,this manuscript shows how to apply a parameterization method in 3D blade design process into adjoint *** all design parameters can therefore be treated as design variables in the adjoint method and then participate in the sensitivity-based ***,a fitted Rotor 67 blade is optimized and the adiabatic efficiency is significantly improved by nearly 0.91%.

关键词： Adjoint method Parameterization method Aerodynamic optimization Customized blading method Compressor Turbomachinery

Numerical study on the effective thermal conductivity and thermal tortuosity of porous media with different morphologies

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Science China(Technological Sciences) 2024年第6期67卷 1685-1694页

作者： DU Shen li Dong li Meng-Jie He Ya-ling Key Laboratory of Thermo-Fluid Science and engineering of Ministry of education School of Energy and Power EngineeringXi’an Jiaotong UniversityXi’an710049China

effective thermal conductivity and thermal tortuosity are crucial parameters for evaluating the effectiveness of heat conduction within porous *** direct pore-scale numerical simulation method is applied to investigate the heat conduction processes inside porous structures with different *** thermal conduction performances of idealized porous structures are directly compared with real foams across a wide range of *** foam structures are reconstructed using X-ray computed tomography and image processing techniques,while Kelvin and Weaire-Phelan structures are generated through periodic unit cell *** detailed temperature fields inside the porous structures are determined by solving the heat conduction equation at the pore *** results present that the equivalent thermal conductivity of Kelvin and Weaire-Phelan structures is similar to and greater than that of the real foam structure with the same strut *** thermal tortuosity of real foam structure is relatively larger and the heat conduction path becomes straighter by adopting the anisotropic *** thermal tortuosity of the fluid channels for Kelvin,Weaire-Phelan,and real foam structures is close to *** thermal conductivity of porous structures with heat transfer fluid increases as the thermal conductivity ratio of fluid to solid becomes larger.A small porosity of porous media leads to a larger equivalent thermal conductivity due to the dominant contribution of porous skeleton in the heat conduction *** derived from parallel and series models,as well as the Maxwell-eucken models,provide decent predictions of effective thermal conductivity,with an average error of less than 8%in the entire range of thermal conductivity ratio.

关键词： volumetric solar receiver porous morphology direct pore-scale simulation equivalent thermal conductivity thermal tortuosity empirical correlation

The relaxation of galaxy clusters at redshift z=0 in IllustrisTNG simulation

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Research in Astronomy and Astrophysics 2020年第12期20卷 261-269页

作者： Chao li ling Zhu Rui Guo National Astronomical Observatories Chinese Academy of SciencesBeijing 100101China University of Chinese Academy of Sciences Beijing 100049China Shanghai Astronomical Observatory Chinese Academy of SciencesShanghai 200030China

We study the dynamical states of the 30 most massive galaxy clusters in the TNG100 simulation at redshift z = 0 using three types of tracers: stars, dark matter particles and satellite galaxies. If the massive galaxy cluster is spherically symmetric and relaxed, we can obtain the underlying total mass distribution accurately from its dynamical tracers using the spherical Jeans equations. Although the three tracers of clusters have very different number densities, velocity dispersions and anisotropies, they still trace the same total mass profile. We obtain the total mass profiles of clusters using these tracers separately and compare them with the true mass distributions. We find that:(1) the kinematics of dark matter trace the total mass of all clusters well and the mass inferred from dark matter are generally consistent with the true mass profiles with relative deviations smaller than ~ 25% at all radii;(2) stars in ~ 60% massive clusters are approaching equilibrium and the total mass of these clusters inferred from stars have relative deviations smaller than ~50% at all radii. Stellar substructures are rich and the mass inferred from stars tend to be over-estimated in the inner region;and(3) satellite galaxies are unrelaxed in the inner region and become more relaxed as the radius increases. The total mass inferred from satellites are under-estimated in all regions.

关键词： galaxies:clusters:general galaxies:clusters:dynamical tracers methods:numerical

FILTeRING CHARACTeRISTICS AND eXPeRIMeNTAL INVeSTIGATION OF ONe-DIMeNSIONAL PeRIODIC RODS

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Chinese Journal of Mechanical engineering 2008年第2期21卷 53-57页

作者： ZHeNG ling li Yinong BAZ Amr State Key Laboratory of Mechanical Transmission Chongqing University Chongqing 400044 China Department of Mechanical engineering University of Maryland College Park MD20742 USA

Passive periodic structures exhibit unique dynamic characteristics that make the passive periodic structures act as mechanical filters for wave propagation. As a result, wave can propagate along the periodic structures only within specific frequency bands called the pass bands and wave propagation is completely blocked within other frequency bands called the “stop bands”. A theoretical method based on the transfer matrix formulation is developed in order to effectively investigate the influence of periodicity, variable geometry and material properties on the wave propagation characteristics of one-dimensional periodic rod. Several numerical examples are presented in order to illustrate their unique tunable filtering and localization characteristics. The experiments are conducted to verify the numerical predictions and to demonstrate the capability of the wavelet transform as a very powerful tool to uniquely identify and compare the energy distribution both in the time and frequency domain. The flexibility that the spectral width and location of the pass and stop bands can be tuned by introducing intentional variation in geometric and material properties for the individual substructure or cell is identified completely by both numerical predictions and experimental results. The results demonstrate the potential of such one-dimensional periodic structure in controlling the dynamics of wave propagation as a mechanical filter such as engine mount, gearbox support strut and other applications.

关键词： Periodic structure Rod Wave propagation Stop bands Wavelet

The river chief system and agricultural non-point source water pollution control in China

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Journal of Integrative Agriculture 2021年第5期20卷 1382-1395页

作者： ZHOU li li ling-zhi HUANG Ji-kun College of economics and Management Nanjing Agricultural UniversityNanjing 210095P.R.China China Center for Agricultural Policy School of Advanced Agricultural SciencesPeking UniversityBeijing 100871P.R.China Jiangxi Agricultural University Nanchang 330045P.R.China

As part of their efforts to control water pollution,local governments in China introduced the river chief system,whereby a named individual undertakes responsibility for protecting a specified *** one of the most prominent sources of water pollution,agricultural non-point-source(NPS)pollution is becoming increasingly *** whether the river chief system,an institutional reform in China's decentralized environmental regulation regime,is effective in alleviating NPS pollution is important for the realization of green *** effect of the river chief system on reducing agricultural NPS pollution is explored in this study using panel data from 308 Chinese counties during the period from 2004 to *** results reveal that the negative impact of manure output from animal breeding operations on surface water quality is reduced with the implementation of the river chief ***,the river chief system is ineffective in dealing with the water pollution caused by fertilizer ***,in the current system,cooperation among river chiefs only occurs within a *** governments should increase their efforts in reducing fertilizer source loads and preventing fertilizer loads from entering surface *** addition,the central government should improve cooperation among the river chiefs in upstream and downstream provinces.

关键词： river chief system agricultural non-point-source pollution surface water quality fertilizer use livestock and poultry breeding

Kinetics of photoelectrocatalytic degradation of humic acid using B_2O_3·TiO_2/Ti photoelectrode

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Journal of environmental Sciences 2005年第2期17卷 208-211页

作者： JIANGYan-li liUHui-ling LUChun-mei Departmentofenvironmentalengineering HarbinInstituteofTechnologyHarbin150001China／／SchoolofLifeScienceandChemistryHarbinCollegeHarbin150001China Departmentofenvironmentalengineering HarbinInstituteofTechnologyHarbin150001China

An innovative photoelectrode, B 2O 3·TiO 2/Ti electrode, was prepared by galvanostaticanodisation. The morphology and crystalline texture of the B 2O 3·TiO 2 film on electrode were examined by atomic force microscopy(AFM) and X-ray diffraction respectively. The examination results indicated that the anatase was the dominant component. The kinetics of photoelectrocatalytic(PeC) degradation of humic acid(HA) was investigated; the results demonstrated that effects from strongness to weakness on the photoelectrocatalytic degraded rate of humic acid: power of UV-lamp, area of TiO 2 film, bias, original concentration of humic acid solution. The optimum conditions were power of UV-lamp 125 W, area of TiO 2 film 42.0 cm 2, bias 1.4 V, original concentration of humic acid solution 5 mg/L in this PeC reaction system.

关键词： TiO 2 photoelectrocatalytic degradation humic acid kinetics

effects of molybdenum on nutrition, quality, and flavour compounds of strawberry (Fragaria×ananassa Duch. Cv. Akihime) fruit

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Journal of Integrative Agriculture 2017年第7期16卷 1502-1512页

作者： liU li XIAO Wei JI Mei-ling YANG Chao li ling GAO Dong-sheng FU Xi-ling State Key Laboratory of Crop Biology College of Horticulture Science and Engineering Shandong Agricultural University

Molybdenum （Mo） is an essential trace element in plant nutrition and physiology. It affects photosynthesis and photosyn- thate accumulation, therefore also affecting fruit quality and nutritional content. This study assessed the effects of different sodium molybdate （Na2MoO4） concentrations on strawberry. Five different Mo concentrations were applied in this experi- ment, including 0, 67.5, 135, 168.75, 202.5 g ha-1, respectively. The mineral concentration, including nitrogen （N）, Mo, iron （Fe）, copper （Cu）, and selenium （Se） was assessed in strawberry fruit, as well as chlorophyll content, nutrition quality, taste and aroma. Results showed that net photosynthetic rate （Pn） and chlorophyll content for the strawberry plants increased with an increase in Mo concentration; and the contents of N, Mo, Fe, Cu, total soluble solids （TSS）, titratable acidity （TA）, sweetness, some sugars, organic acids, and some volatile compounds in the fruit all increased, as well. However, the Mo concentration did not significantly affect the concentrations of Se, sucrose, lactic acid, acetic acid, and some aroma compounds. Fruit sprayed with 135 g ha-1 Mo exhibited the highest TSS and sweetness values, as well as the highest N and Fe concentrations among all the treatments. P value and chlorophyll content, fructose, glucose, sorbitol and total sugar contents in fruit supplied with 135 g ha-1 Mo were also higher than that in other treatments. Fruit sprayed with a Mo concentration of 67.5 g ha-1 exhibited significantly higher ascorbic acid （AsA） values than that of control. Ninety-seven volatile compounds were identified in fruit extracted by head-space solid-phase microextraction （HS-SPMe） coupled with gas chromatography-mass spectrometry （GC-MS）. Fruits sprayed with 135 g ha-1 Mo had the highest concentrations of six characteristic aroma compounds, including methyl butanoate, y-decalactone, ethyl butanoate, methyl hexanoate, y-do- decalactone, and ethyl caproate.

关键词： strawberry molybdenum nutrition volatile compounds flavour

Finite-State Markov Wireless Channel Modeling for Railway Tunnel environments

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China Communications 2020年第2期17卷 30-39页

作者： Cuiran li ling liu Jianli Xie School of electronic and Information engineering Lanzhou Jiaotong University

In recent years,high-speed railways(HSRs)have developed rapidly with a high transportation capacity and high comfort level.A tunnel is a complex high-speed rail terrain *** is very important to establish an accurate channel propagation model for a railway tunnel environment to improve the safety of HSR *** this paper,a method for finite-state Markov chain(FSMC)channel modeling with least squares fitting based on non-uniform interval division is ***,a path loss model is obtained according to measured *** communication distance between the transmitter and receiver in the tunnel is non-uniformly divided into several large non-overlapping intervals based on the path loss ***,the Lloyd-Max quantization method is used to determine the threshold of the signal-to-noise ratio(SNR)and the channel state quantization value and obtain the FSMC state transition probability *** experiments show that the proposed wireless channel model has a low mean square error(MSe)and can accurately predict the received signal power in a railway tunnel environment.

关键词： railway tunnel FSMC channel model SNR path loss