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Microphysical Insights into a Tornadic Supercell from Dual-Polarization Radar Observations in Jiangsu, China on 14 May 2021

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Journal of Meteorological Research 2024年第2期38卷 303-320页

作者： chao YUAN Yang BAI Pengfei SUN Hua BAI Lu xia China Meteorological Administration Tornado Key Laboratory Foshan 528315 Institute of Atmospheric Environment China Meteorological AdministrationShenyang 110166 Panjin National Climate Observatory Panjin 124010 Yangzhou Meteorological Bureau of Jiangsu Province Yangzhou 225100 Yichun Meteorological Bureau of Heilongjiang Province Yichun 153000

Tornadoes are incredibly powerful and destructive natural events,yet the microphysical characteristics of the parent storm and its effects on tornadogenesis remain unclear.This study analyzed polarization radar data of a tornadic supercell that occurred in Jiangsu Province of China on 14 May 2021,in comparison with another tornadic supercell and two non-tornadic supercells that occurred in the same region in 2023.The two tornadic supercells exhibited lower differential reflectivity(ZDR)in the hook echo region compared with the non-tornadic supercells,indicating smaller median drop sizes.A distinct increase in ZDR from the melting of frozen hydrometeors,observed between2.5-and 4.0-km altitude in the non-tornadic storms,was absent in the tornadic cases.The non-tornadic supercells also displayed substantially higher specific differential phase(KDP)below the melting level,likely aroused from enhanced melting and cooling.These findings suggest fundamental microphysical contrasts between tornadic and nontornadic supercells.Specifically,tornadic supercells have smaller droplets and may reduce melting in hook echoes.Moreover,greater separation between the ZDR arc and the KDP foot was observed during tornadogenesis.The vertical gradient of KDP related to the cooling pool strength of the hook echo,regulating rear-flank downdraft thermodynamics.Despite the limited number of cases investigated,the findings of this study indicate that monitoring ZDR,KDP,and drop size distribution trends could assist with tornado prediction and warnings.

关键词： tornado polarimetric radar supercell hook echo drop size distribution

Behavior of sulfate in preparation of single light rare earth carbonate by Mg(HCO_(3))_(2) precipitation method

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Journal of Rare Earths 2021年第7期39卷 850-857,I0004页

作者： Meng Wang xiaowei Huang Zongyu Feng Chao Xia Deliang Meng Zonghe Yu National Engineering Research Center for Rare Earth Materials GRINM Group Co.Ltd.Beijing 100088China GRIREM Advanced Materials Co. Ltd.Beijing 100088China General Research Institute for Nonferrous Metals Beijing 100088China Rare Earth Functional Materials(Xiong'an)Innovation Center Co. Ltd.Baoding 071700China

The precipitation of the water-leaching solution of Baotou mixed rare earth(RE) concentrate roasted with sulfuric acid using ammonium bicarbonate for producing RE carbonate produces a mass of ammonia-nitrogen wastewater because of the relatively low solubility of rare earth sulfate.To solve the serious problem of ammonia-nitrogen pollution,new precipitators need to be developed urgently so as to meet the requirements of environmental protection and impurities content of the product(SO_(4)^(2-)<1.8 wt% in RE carbonates products).In this paper,we studied the effects of feeding modes on the behavior of SO_(4)^(2-) during the preparation of light RE carbonate(RE=La,Ce,Pr,Nd) from their sulfate solutions using Mg(HCO_(3))_(2) as a precipitant.The results indicate that the contents of SO_(4)^(2-) in the La and Ce precipitates using positive feeding mode exceed 16 wt% because of the formation of La_(2)(CO_(3))2.15(-SO_(4))0.85·4 H_(2)O and Ce_(2)(CO_(3))_(2).15(SO_(4))0.85·3H_(2)O,while those of the Pr and Nd precipitates are 4 wt%-5 wt% since they exist in the form of n-carbonate.The precipitates prepared using synchronous feeding mode are all RE carbonate with only 4 wt%-5 wt% of SO_(4)^(2-) enclosed in the precipitation.The content of SO_(4)^(2-) in the RE carbonate obtained using reverse feeding mode is the lowest.Among them,the content of SO_(4)^(2-) in La precipitate is only 1.40 wt%.Both synchronous and reverse feeding modes can effectively reduce the content of SO_(4)^(2-)in RE carbonate,which provides theoretical guidance for the preparation of qualified light RE carbonate products by Mg(HCO3)2 precipitation method.

关键词： Rare earth sulfate Magnesium bicarbonate Rare earth carbonate Sulfate ion Complex salt

Mechanism and control technology of strong ground pressure behaviour induced by high-position hard roofs in extra-thick coal seam mining

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International Journal of Mining Science and Technology 2022年第3期32卷 499-511页

作者： chao Pan Binwei xia Yujun Zuo Bin Yu Changnan Ou Mining College Guizhou UniversityGuiyang 550025China National&Local Joint Engineering Laboratory of Gas Drainage in Complex Coal Seam Chongqing UniversityChongqing 400044China State Key Laboratory of Coal Mine Disaster Dynamics and Control Chongqing UniversityChongqing 400044China

This work aimed at revealing the mechanism of strong ground pressure behaviour(SGPB)induced by high-position hard roof(HHR).Based on the supporting structures model of HHR,a modified voussoir beam mechanical model for HHR was established by considering the gangue support coefficient,through which the modified expressions of limit breaking span and breaking energy of HHR were deduced.Combined with the relationship between the dynamic-static loading stress of supporting body(hydraulic support and coal wall)and its comprehensive supporting strength,the criteria of ground pressure behaviour(GPB)induced by HHR were discussed.The types of Ⅰ_(1),Ⅰ_(2),Ⅱ_(1),andⅡ_(2) of GPB were interpreted.Results showed that types Ⅰ_(1) and Ⅰ_(2) were the main forms of SGPB in extra-thick coal seam mining.The main manifestation of SGPB was static stress,which was mainly derived from the instability of HHR rather than fracture.Accordingly,an innovative control technology was proposed,which can weaken static load by vertical-well separated fracturing HHR.The research results have been successfully applied to the 8101 working face in Tashan coal mine,Shanxi Province,China.The results of a digital borehole camera observation and stress monitoring proved the rationality of the GPB criteria.The control technology was successful,paving the way for new possibilities to HHR control for safety mining.

关键词： Extra thick coal seam High-position hard roof Strong ground pressure behaviour Supporting structures Criteria of ground pressure behaviour Controlling effects

Reaction between tetravalent cerium ion and chloride ion and effect of thiourea using cyclic voltammetry

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Journal of Rare Earths 2022年第10期40卷 1635-1640页

作者： Deliang Meng xiaowei Huang Zongyu Feng Meng Wang Juanyu Yang Chao Xia Yanyan Zhao Yuqing Wei School of Metallurgy Northeastern UniversityShenyang 110819China National Engineering Research Center for Rare Earth Materials GRINM Group Co.Ltd.Beijing 100088China GRIREM Advanced Materials Co. Ltd.Beijing 100088China General Research Institute for Nonferrous Metals Beijing 100088China

To monitor the reaction between Ce^(4+) ion and Cl-ion at the electron level,an electrochemical experiment was designed in this work.Herein,the intermediate and final products that may be produced during the redox reaction are directly tracked by using cyclic voltammetry,and the influences of Ce^(4+) ion concentration,temperatu re and F-ion on the reduction peak potential of Ce^(4+) ion were investigated.The results show that Ce^(4+) ion reacts with Cl-ion through an irreversible reaction without any intermediate products,and the rate-determining step of the reaction is diffusion during the electrode reaction.The effects of temperature(20-40℃) and Ce^(4+) ion concentration(0.04-0.12 mol/L) on the reduction peak pote ntial of Ce^(4+) ion can be ignored,but the higher the molar ratio of F-to Ce^(4+)(0-3 mol/mol),the mo re easily the reduction of Ce^(4+) ion to Ce^(3+) ion occurs.Additionally,the Ce^(4+) ions are preferentially reduced by thiourea when thiourea is added in the HCl solution,and thiourea inhibits the oxidation of Cl-ions to Cl_(2) by forming a complex with Cl-ions.This work provides a theoretical basis for the role of thiourea in inhibiting Cl_(2) production and offers a new way to find new reductants.

关键词： Electrochemical test Cyclic voltammetry Redox reaction Rare earths

Effects of Br−on NDMA Formation During Chloramination:a Review of Influencing Factors,Mechanisms,and Control

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Chemical Research in Chinese Universities 2023年第3期39卷 370-377页

作者： xia Ruanjunjie LIAO xiaobin LIU Tianze GAO Menglan CHEN chao Institute of Municipal and Environmental Engineering College of Civil EngineeringHuaqiao UniversityXiamen361021P.R.China State Key Joint Laboratory of Environment Simulation and Pollution Control School of EnvironmentTsinghua UniversityBeijing100084P.R.China

For the invasion of seawater and the stress of human activities,bromide ion(Br−)exists widely in drinking water sources,and it was found to influence the formation of non-brominated but carcinogenic nitrogen-containing disinfection by-product nitroso-dimethylamine(NDMA)during chloramination(NH2Cl).The presence of Br−leads to the formation of bromine-active species,such as bromamines(NH2Br),bromochloramine(NHClBr),as well as hypobromous acid(HOBr),which are more reactive with NDMA precursors than chlorine-active species,so might promote NDMA generation.This review mainly focuses on the influencing laws,as well as the factors(disinfection conditions and characteristics of water matrixes)that affected NMDA formation during chloramination with Br−.In addition,the possible influencing pathways are discussed.Finally,based on the above summary,measures pertaining to reduce the impact of Br−on NDMA production are concluded.This review would provide a theoretical reference for drinking water treatment plants to deal with bromine-containing water during chloramination.

关键词： Bromide ion Disinfection by-product Nitrosodimethylamine(NDMA) Chloramination

Gauss-Bonnet-Chern mass and Alexandrov-Fenchel inequality

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Frontiers of Mathematics in China 2016年第5期11卷 1207-1237页

作者： Yuxin GE Guofang WANG Jie WU Chao Xia Institut de Math~matiques de Toulouse Universite Paul Sabatier 118 route de Narbonne 31062 Toulouse Cedex France Albert-Ludwigs-Universitat Freiburg Mathematisches Institut Eckerstr 1 D-79104 Freiburg Germany Department of Mathematics Zhejiang University Hangzhou 310027 China School of Mathematical Sciences Xiamen University Xiamen 361005 China

This is a survey about our recent works on the Gauss-Bonnet-Chern （GBC） mass for asymptotically flat and asymptotically hyperbolic manifolds. We first introduce the GBC mass, a higher order mass, for asymptotically flat and for asymptotically hyperbolic manifolds, respectively, by using a higher order scalar curvature. Then we prove its positivity and the Penrose inequality for graphical manifolds. One of the crucial steps in the proof of the Penrose inequality is the use of an Alexandrov-Fenchel inequality, which is a classical^inequality in the Euclidean space. In the hyperbolic space, we have established this new Alexandrov-Fenchel inequality. We also have a similar work for asymptotically locally hyperbolic manifolds. At the end, we discuss the relation between the GBC mass and Chern＇s magic form.

关键词： Gauss-Bonnet-Chern （GBC） mass Gauss-Bonnet curvature positive mass theorem （PMT） asymptotically hyperbolic manifold Penrose inequality Alexandrov-Fenchel inequality

Impurities analysis of high-purity osmium target for M-cathode application

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Rare Metals 2023年第4期42卷 1154-1159页

作者： Jun-Da Ma Yang xia Yuan-Feng Xie chao Zhang GRIMAT Engineering Institute Co. LtdBeijing101407China State Key Laboratory of Advanced Materials for Smart Sensing GRINM Group Co.LtdBeijing101407China General Research Institute for Nonferrous Metals Beijing100088China

Impurities and their distributions in osmium targets for M-type cathodes affect the coating quality on porous tungsten and cathode emission performance.Glow discharge mass spectrometry(GDMS)and X-ray photoelectron spectroscopy(XPS)were used to analyze the impurity contents and distributions in the osmium target.The chemical states of impurity elements were analyzed and characterized.The total amount of metallic impurity in the target was lower than 0.01 wt%.

关键词： osmium Impurities purity

Re-Os Geochronology of the Liuchapo Formation across the Ediacaran-Cambrian Boundary of the Yangtze Block(South China)

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Journal of Earth Science 2022年第1期33卷 25-35页

作者： Yong Fu Fuliang Wang Chuan Guo chao Li Peng xia College of Resource and Environmental Engineering Guizhou UniversityGuiyang 550025China Key Laboratory of Karst Georesources and Environment Ministry of EducationGuizhou UniversityGuiyang 550025China Guizhou Geological Environment Monitoring Institute Guizhou 550081China National Research Center for Geoanalysis Chinese Academy of Geological SciencesBeijing 100037China

The Ediacaran-Cambrian(E-C) succession in South China records remarkable oceanic,biological and geochemical variations,but it was not well defined geochronologically,which hinders the interpretation of the spatio-temporal seawater chemical architecture during the time E-C interval.This study presents two Re-Os isochron ages of 520.2±6.1 and 561.7±8.5 Ma for the barite-rich black shales from the top Liuchapo and Doushantuo formations respectively in Tianzhu County,Guizhou Province.In combination with existing age data,the two new Re-Os isochron ages suggest that the Liuchapo Formation was deposited between 550 and 520 Ma.Moreover,like the polymetallic Ni-MoPGE layers of shelf margin(or platform) facies and V-rich horizons of transitional(or shelf slope) to deep-water facies,the barite deposits were likely formed due to differential mineralization.The timing offset likely resulted from differential elemental concentration related to certain local factors(i.e.,hydrothermal fluids,seawater redox and biological activity).The isochron-derived initial ^(187)Os/^(188)Os ratios of the top Liuchapo Formation(0.902 ± 0.048) and the Doushantuo Formation(0.740 ± 0.042) fall within the range of continental weathering flux(1.54) and oceanic crust(0.126),implying the involvement of marine hydrothermal fluids.Moreover,their difference of initial ^(187)Os/^(188)Os ratios may reflect variations of continental weathering intensity and uplift magnitude.

关键词： geochemistry Ediacaran-Cambrian initial^(187)Os/^(188)Os Liuchapo Formation Re-Os isotope Yangtze Block

Effect of Microstructural Characteristics on Fracture Toughness in Direct Energy Deposited Novel Ti-6Al-4V-1Mo Alloy

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Acta Metallurgica Sinica(English Letters) 2024年第1期37卷 119-131页

作者： Chao Xia Kexin Zhao Xin Zhou Yuqi He Panpan Gao Hengxin Zhang Guangrui Gao Fengying Zhang Hua Tan School of Material Science and Engineering Chang’an UniversityXi’an710064China Science and Technology on Plasma Dynamics Laboratory Air Force Engineering UniversityXi’an710038China State Key Laboratory of Solidification Processing Northwestern Polytechnical UniversityXi’an710072China Surface Material Protection Co. LtdXi’an710018China

Meeting the damage tolerance requirements for engineering-grade titanium alloys pose a significant challenge in achieving high fracture toughness in direct energy deposition(DED)titanium alloys.This work primarily investigated the relationship between the microstructure and the fracture toughness of DED new Ti-6Al-4V-1Mo alloy.Two types of microstructures were designed via two process strategies:high-line energy density(HE)and low-line energy density(LE).Relative to LE samples,HE samples possess larger-sized microstructural characteristics(coarser grain boundaryα(α_(GB)),largerαcolonies,and coarserαlaths).Lessα/βphase boundaries were formed by coarserαlaths in the HE samples,increasing the movement of dislocations,resulting in tensile strength decreasing from 1007.1 MPa(LE)to 930.8 MPa(HE)and elongation increasing from 10.8%(LE)to 15.7%(HE).Also,HE samples exhibited an excellent fracture toughness of 114.0 MPa m^(1/2),significantly higher than that of LE samples(76.8 MPa m^(1/2)).An analysis of crack propagation paths was conducted to investigate the factors contributing to toughening.The primary factor enhancing toughness is the frequent obstruction of cracks by coarseαGB and largeαcolonies in HE samples.Particularly,the pretty large-angle deflections induced by the superposition effect of coarseαGB and largeαcolonies play a vital of significant role.These factors induced the long and tortuous high-energy pathways,which resulted in ultimately improved fracture toughness.The discovered microstructural toughening mechanisms can serve as a reference for future studies involving titanium alloys,offering insights on how to enhance fracture toughness by achieving similar characteristics.

关键词： Direct energy deposition Ti-6Al-4V-1Mo Tensile properties Fracture toughness Crack propagation