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Numerical simulations for radon migration and exhalation behavior during measuring radon exhalation rate with closed-loop method

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Nuclear Science and Techniques 2024年第1期35卷 81-95页

作者： Ming xia yong-Jun Ye Shu-Yuan Liu School of Resources Environment and Safety Engineering University of South ChinaHengyang 421001China Key Discipline Laboratory for National Defense for Biotechnology in Uranium Mining and Hydrometallurgy University of South ChinaHengyang 421001China

Accurate measurements of the radon exhalation rate help identify and evaluate radon risk regions in the *** these measurement methods,the closed-loop method is frequently ***,traditional experiments are insufficient or cannot analyze the radon migration and exhalation patterns at the gas–solid interface in the accumulation *** CFD-based technique was applied to predict the radon concentration distribution in a limited space,allowing radon accumulation and exhalation inside the chamber intuitively and *** this study,three radon exhalation rates were defined,and two structural ventilation tubes were designed for the *** consistency of the simulated results with the variation in the radon exhalation rate in a previous experiment or analytical solution was *** effects of the vent tube structure and flow rate on the radon uniformity in the chamber;permeability,insertion depth,and flow rate on the radon exhalation rate and the effective diffusion coefficient on back-diffusion were *** on the results,increasing the inser-tion depth from 1 to 5 cm decreased the effective decay constant by 19.55%,whereas the curve-fitted radon exhalation rate decreased(lower than the initial value)as the deviation from the initial value increased by approximately 7%.Increasing the effective diffusion coefficient from 2.77×10^(-7) to 7.77×10^(-6) m^(2) s^(-1) made the deviation expand from 2.14 to 15.96%.The conclusion is that an increased insertion depth helps reduce leakage in the chamber,subject to notable back-diffusion,and that the closed-loop method is reasonably used for porous media with a low effective diffusion coefficient in view of the back-diffusion *** CFD-based simulation is expected to provide guidance for the optimization of the radon exhalation rate measurement method and,thus,the accurate measurement of the radon exhalation rate.

关键词： Radon exhalation Numerical simulation Accumulation chamber

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Mechanism and control of nonuniform phase transformation of microalloyed dual-phase steel during cooling process after hot rolling

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Journal of Iron and Steel Research(International) 2024年第2期31卷 428-441页

作者： Wen-quan Sun Sheng-yi yong Tie-heng Yuan Chao Liu San-bao zhou Rui-chun Guo Meng-xia Tang National Engineering Research Center for Advanced Rolling and Intelligent Manufacturing University of Science and Technology BeijingBeijing100083China Strip Production Plant Xichang Steel and Vanadium Corporation of Pangang GroupXichang615000SichuanChina

After cooling in the hot rolling process,the metallographic structure of microalloyed dual-phase steel is nonuniform along the rolling direction,while the thickness fluctuation of microalloyed dual-phase steel with a nonuniform metallographic structure will occur during cold *** mechanism of nonuniform phase transformation of microalloyed dual-phase steels was studied during the cooling process after hot rolling,and the nonuniform phase transformation of microalloyed dual-phase steel was regulated during the cooling process after hot rolling through process ***,the empirical equation of phase transformation temperature was measured by a dilatometer considering thermal ***,the phase field and temperature field of laminar cooling process were calculated to provide initial boundary conditions for the finite element *** that,the coupling finite element model of the temperature phase transformation of the strip steel in coiling transportation process was *** simulation results show that the different thermal contact conditions of the microalloyed dual-phase steel during coil transportation lead to uneven cooling of the coil,which leads to nonuniform transformation of the coil along the rolling *** addition,by prolonging the time interval from coiling to unloading,the phenomenon of nonuniform phase transformation of microalloyed dual-phase steel can be effectively *** simulation results are applied to industrial *** application results show that prolonging the time interval from coiling to unloading can effectively improve the nonuniform phase transformation of microalloyed dual-phase steel in the cooling process after hot rolling.

关键词： Microalloyed dual-phase steel Thickness fluctuation Cooling Heat conduction Nonuniform phase transition Finite element method

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Biogenic volatile organic compounds dominated the near-surface ozone generation in Sichuan Basin,China,during fall and wintertime

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Journal of Environmental Sciences 2024年第7期141卷 215-224页

作者： Dasheng Huang Qing Li Yan Han Shi-yong xia Jiawei zhou Hanxiong Che Keding Lu Fumo Yang Xin Long Yang Chen Research Center for Atmospheric Environment Chongqing Institute of Green and Intelligent TechnologyChinese Academy of SciencesChongqing 400714China Chongqing Institute of Green and Intelligent Technology Chinese Academy of SciencesChongqing 400714China College of Resources and Environment Chongqing SchoolUniversity of the Chinese Academy of Sciences(UCAS Chongqing)Chongqing 400714China College of Environmental and Chemical Engineering Chongqing Three Gorges UniversityChongqing 404199China Key Laboratory for Urban Habitat Environmental Science and Technology School of Environment and EnergyPeking University Shenzhen Graduate SchoolLishui RoadNanshan DistrictShenzhen 518055China SKL-ESPC and BIC-ESAT College of Environmental Sciences and EngineeringPeking UniversityBeijing 100871China College of Architecture&Environment Sichuan UniversityChengdu 610065China

The complex air pollution driven by both Ozone(O_(3))and fine particulate matter(PM2.5)sig nificantly influences the air quality in the Sichuan Basin(SCB).Understanding the O_(3)for mation during autumn and winter is necessary to understand the atmospheric oxidative ***,continuous in-site field observations were carried out during the late summer,early autumn and winter of 2020 in a rural area of *** total volatile organic compounds(VOCs)concentration reported by a Proton-Transfer-Reaction Time-of Flight Mass Spectrometry(PTR-ToF-MS)were 13.66±9.75 ppb,5.50±2.64 ppb,and 9.41±5.11 ppb in late summer,early autumn and winter,*** anthropogenic VOCs(AVOCs)and biogenic VOCs(BVOCs)were 8.48±7.92 ppb and 5.18±2.99 ppb in late sum mer,3.31±1.89 ppb and 2.19±0.93 ppb in autumn,and 6.22±3.99 ppb and 3.20±1.27ppb in winter.A zero-dimensional atmospheric box model was employed to investigate the sensitivity of O_(3)-precursors by relative incremental reactivity(RIR).The RIR values of AV OCs,BVOCs,carbon monoxide(CO),and nitrogen oxides(NOx)were 0.31,0.71,0.09,and-0.36 for late summer,0.24,0.59,0.22,and-0.38 for early autumn,and 0.30,0.64,0.33 and-0.70 for winter,and the results showed that the O_(3)formation of sampling area was in the VOC-limited region,and O_(3)was most sensitive to BVOCs(with highest RIR values,>0.6)This study can be helpful in understanding O_(3)formation and interpreting the secondary formation of aerosols in the winter.

关键词： VOCs PTR-MS Model Ozone

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BLOCK ITERATIVE METHODS FOR LINEAR ALGEBRAIC EQUATION AND DOMAIN DECOMPOSITION METHOD FOR INCOMPRESSIBLE VISCOUS FLOW

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Journal of Hydrodynamics 2002年第4期14卷 73-80页

作者： Ren, An-Lu Zou, Jian-Feng zhou, yong-xia Li, Guang-Wang Dept. of Mech. Zhejiang Univ. Hangzhou 310027 China

It was proved numerically that the Domain Decomposition Method CDDM) with one layer overlapping grids is identical to the block iterative method of linear algebra equations. The results obtained by using DDM could be in reasonable agreement with the results of full-domain simulation. With the three dimensional solver developed by the authors, the flow field in a pipe was simulated by using the full-domain DDM with one layer overlapping grids and with patched grids respectively. Both of the two cases led to the convergent solution. Further research shows the superiority of the DDM with one layer overlapping grids to the DDM with patched grids. A comparison between the numerical results obtained by the authors and the experimental results given by Enayet[3] shows that the numerical results are reasonable.

关键词： Computational fluid dynamics Computer simulation Iterative methods Linear equations Viscous flow

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Metallogenesis of the Baidi Au-Sb deposit, southwest Guizhou Province, China: mineralogical and geochemical evidence from sulfur-bearing minerals

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Acta Geochimica 2024年第2期43卷 199-213页

作者： Jun Yan yong xia Qinping Tan Zhuojun Xie Guosong Ji State KeyLaboratory of Ore Deposit Geochemistry Institute of GeochemistryChineseAcademy of SciencesGuiyang 550081China Guizhou InstituteofTechnology Guiyang550003China No.102 GeologicalTeam Guizhou Bureau of Geologyand Mineral Exploration&DevelopmentZunyi563003China

The Baidi Au-Sb deposit, which contains 8 t of Au and 10,979 Mt of Sb, is a typical and rare paragenetic deposit located in southwestern Guizhou Province, *** studies have focused on individual ores, but have not combined them to identify their paragenetic mechanism or metallogenic regularity. Therefore, we used field investigations, microscopic observations, and in situ analyses to identify the spatial distribution, mineral paragenesis, compositional evolution, and metallogenic material sources of the ore bodies. We also determined the Au and Sb paragenetic characteristics and the metallogenesis of the deposit. The main Au-bearing minerals in the deposit were early(Apy1–2) and late(Apy3) stage arsenopyrites, as well as pre-mineralization(Py1), mineralization(Py2–5), and late mineralization(Py6–7) stage pyrites. The main Sb-bearing minerals were stibnite(Snt), skinnerite, bournonite,and valentinite. The minerals formed in the order of Py1,Py2–3 + Apy1, Py4–5 + Apy2, Snt, and Py6–7 + *** δ34S values of the arsenopyrites and pyrites ranged from-5 to 5‰, while those of stibnite were mostly less than-5‰ in the later mineralization stages. Sulfur was provided by deep magmatic hydrothermal fluids, but sedimentary sulfur was added in the later stages. Moreover,the trace elemental contents fluctuated and eventually became similar to those of the sedimentary strata. By comprehensively considering the ores along with the geological characteristics of the deposit, we determined that deep magma provided the Au during ore formation. Later tectonic changes provided Sb from the sedimentary strata,which precipitated along fault expansion areas and produced Au and Sb paragenesis.

关键词： Au-Sb mineralization Arsenopyrite Pyrite Stibnite Metallogenetic process

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Dynamic simulation insights into friction weakening effect on rapid long-runout landslides:A case study of the Yigong landslide in the Tibetan Plateau,China

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China Geology 2024年第2期7卷 222-236页

作者： Zi-zheng Guo Xin-yong zhou Da Huang Shi-jie Zhai Bi-xia Tian Guang-ming Li School of Civil and Transportation Engineering Hebei University of TechnologyTianjin 300401China School of Geological Engineering and Geomatics Chang’an UniversityXi’an 710054China Tianjin Municipal Engineering Design&Research Institute(TMEDI) Tianjin 300392China

This study proposed a novel friction law dependent on velocity,displacement and normal stress for kinematic analysis of runout process of rapid *** well-known Yigong landslide occurring in the Tibetan Plateau of China was employed as the case,and the derived dynamic friction formula was included into the numerical simulation based on Particle Flow *** showed that the friction decreased quickly from 0.64(the peak)to 0.1(the stead value)during the 5s-period after the sliding initiation,which explained the behavior of rapid movement of the *** monitored balls set at different sections of the mass showed similar variation characteritics regarding the velocity,namely evident increase at the initial phase of the movement,followed by a fluctuation phase and then a stopping *** peak velocity was more than 100 m/s and most particles had low velocities at 300s after the landslide *** spreading distance of the landslide was calculated at the two-dimension(profile)and three-dimension scale,*** with the simulation result without considering friction weakening effect,our results indicated a max distance of about 10 km from the initial unstable position,which fit better with the actual situation.

关键词： Rapid long-runout landslide PFC Friction weakening Three-dimension Numerical simulation Tibetan Plateau Hydrogeology Engineering Geological hazards survey engineering

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NUMERICAL SOLUTION OF 2-D INCOMPRESSIBLE VISCOUS FLOW WITH HIGH ORDER COMPACT SCHEME USING DOMAIN DECOMPOSITION AND MATCHED METHOD

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Journal of Hydrodynamics 2001年第4期13卷 79-82页

作者： Ren, An-Lu Lu, xiao-Dong Zou, Jian-Feng zhou, yong-xia Dept. of Mech. Zhejiang Univ. Hangzhou 310027 China

This paper presents a high-accuracy method for solving 2-D incompressible viscous N-S equations in tensor forms. A domain decomposition method was used to divide the computational domain into several regular blocks with the overlapping grid in order to transfer data between sub-domains and to remove numerical singularity caused by domain decomposition. Using the method and algorithm presented above, the flow passing an ellipse was computed and the formation and evolution of the vortex shedding was successfully simulated.

关键词： Computational fluid dynamics Computational methods Incompressible flow Navier Stokes equations

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In-situ measurement via the flow-through method and numerical simulations for radon exhalation during measurements of the radon exhalation rate

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Nuclear Science and Techniques 2024年第7期35卷 192-207页

作者： Ming xia yong-Jun Ye Shan-Wei Shang Ting Yu Dai-Jia Chen School of Resources Environment and Safety Engineering University of South ChinaHengyang421001China Key Discipline Laboratory for National Defense for Biotechnology in Uranium Mining and Hydrometallurgy University of South ChinaHengyang421001China

Small-scale measurements of the radon exhalation rate using the flow-through and closed-loop methods were conducted on the surface of a uranium tailing pond to better understand the differences between the two *** abnormal radon exhalation behavior was observed,leading to computational fluid dynamics(CFD)-based simulations in which dynamic radon migration in a porous medium and accumulation chamber was *** on the in-situ experimental and numerical simulation results,variations in the radon exhalation rate subject to permeability,flow rate,and insertion depth were quantified and *** in-situ radon exhalation rates measured using the flow-through method were higher than those measured using the closed-loop method,which could be explained by the negative pressure difference between the inside and outside of the chamber during the *** consistency of the variations in the radon exhalation rate between the experiments and simulations suggests the reliability of CFD-based techniques in obtaining the dynamic evolution of transient radon exhalation rates for diffusion and convection at the porous medium-air *** synergistic effects of the three factors(insertion depth,flow rate,and permeability)on the negative pressure difference and measured exhalation rate were quantified,and multivariate regression models were established,with positive correlations in most cases;the exhalation rate decreased with increasing insertion depth at a permeability of 1×10^(−11) m^(2).CFD-based simulations can provide theoretical guidance for improving the flow-through method and thus achieve accurate measurements.

关键词： Radon exhalation Flow-through Numerical simulation Accumulation chamber Multivariate regression

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Excess pore pressure behavior and evolution in deep coalbed methane reservoirs

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International Journal of Mining Science and Technology 2024年第6期34卷 763-781页

作者： Changqing Liu Zhaobiao Yang yong Qin xia Yan Yunhai Wang Zhe Wang Key Laboratory of Coalbed Methane Resources and Reservoir Formation Process Ministry of EducationChina University of Mining and TechnologyXuzhou 221008China School of Resources and Geosciences China University of Mining and TechnologyXuzhou 221116China National Engineering Research Center of Coalbed Methane Development&Utilization Beijing 100095China PetroChina Coalbed Methane Company Limited Beijing 102200China SINOPEC East China Oil and Gas Company Nanjing 210000China

Deep coalbed methane(DCBM),an unconventional gas reservoir,has undergone significant advancements in recent years,sparking a growing interest in assessing pore pressure dynamics within these *** some production data analysis techniques have been adapted from conventional oil and gas wells,there remains a gap in the understanding of pore pressure generation and evolution,particularly in wells subjected to large-scale hydraulic *** address this gap,a novel technique called excess pore pressure analysis(EPPA)has been introduced to the coal seam gas industry for the first time to our knowledge,which employs dual-phase flow principles based on consolidation *** technique focuses on the generation and dissipation for excess pore-water pressure(EPWP)and excess pore-gas pressure(EPGP)in stimulated deep coal *** have been developed respectively and numerical solutions have been provided using the finite element method(FEM).Application of this model to a representative field example reveals that excess pore pressure arises from rapid loading,with overburden weight transferred under undrained condition due to intense hydraulic fracturing,which significantly redistributes the weight-bearing role from the solid coal structure to the injected fluid and liberated gas within artificial pores over a brief ***,field application indicates that the dissipation of EPWP and EPGP can be actually considered as the process of well production,where methane and water are extracted from deep coalbed methane wells,leading to consolidation for the artificial ***,history matching results demonstrate that the excess-pressure model established in this study provides a better explanation for the declining trends observed in both gas and water production curves,compared to conventional practices in coalbed methane reservoir engineering and petroleum *** research not only enhances the understanding of DCBM re

关键词： Deep coalbed methane Consolidation Excess pore-water pressure Excess pore-gas pressure Production data analysis

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Sequence-Controlled Synthesis of Alternating Poly(ester amide)s using Water as Control Agent in One-Pot

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Chinese Journal of Polymer Science 2024年第8期42卷 1015-1020页

作者： Tao Liu Fang-Fang Niu Kan Cheng Yu-Min xia Bo-Mou Ma Xue-Li Wang Jian-yong Yu and yong He State Key Laboratory for Modification of Chemical Fibers and Polymer Materials College of Materials Science and EngineeringDonghua UniversityShanghai 201620China Innovation Center for Textile Science and Technology Donghua UniversityShanghai 201620China

Poly(ester amide)s(PEAs)attract much attention as a new kind of biodegradable ***,the synthesis of PEAs with sequence-regulated chain structures is still complicated due to the multistep polymerization,high monomer purity,as well as the usage of organic solvents,which greatly inhibits its development and ***,a one-pot strategy without solvent was developed to synthesize the alternating PEA fromα,ω-amino alcohol and dicarboxylic acid by sequential polycondensation,where water was used as the controlling agent for amidation and ***,the amidation and esterification were controlled to proceed in turn by adding or removing water,realizing the one-pot preparation of alternating *** resultant PEA is characterized by^1H-and^(13)C-NMR,and its chain structure is confirmed to be highly quasi-alternating similar to alternating PEAs prepared by classical methods The evaluations from DSC and DMA demonstrate that the properties of quasi-alternating PEA(T_(m)=102℃,ΔH_(m)=30J·g^(-1))are far superior to those of random PEA(T_(m)=72℃,ΔH_(m)<1 J·g^(-1)).

关键词： Biodegradable macromolecules Polymer architectures Sequence-controlled synthesis One-pot polymerization

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