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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 s.u-yuan liu school of Res.urces 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 s.udy,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

Effect of surfactant frequently used in soil flushing on oxygen mass transfer in micro-nano-bubble aeration system

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Chinese Journal of Chemical Engineering 2024年第3期67卷 174-181页

作者： Mei Bai Zhibin liu Zhu liu Chenfei He Zhanhuang Fan Miaoxin yuan Jiangsu Key Laboratory of urban underground Engineering and Environmental safety Southeast UniversityNanjing 211189China CECEP DADI(Hangzhou)Environmental Remediation Co. Ltd.Hangzhou 310020China

In-site soil flushing and aeration are the typical synergetic remediation technology for contaminated *** surfactant present in flushing solutions is bound to affect the aeration *** purpose of this s.udy is to evaluate the effect of surfactant frequently used in soil flushing on the oxygen mass transfer in micro-nano-bubble(MNB)aeration ***,bio-surfactants and chemical surfactants were used to investigate their effects on s.uter mean diameter of bubble(dBs),gas holdup(ε),volumetric mass-transfer coefficient(kLa)and liquid-side mass-transfer coefficient(kL)in the MNB aeration ***,based upon the experimental results,the sardeing's and Frossling's models were modified to describe the effect of surfactant on kL in the MNB *** results showed that,for the twenty aqueous surfactant solutions,with the increase in surfactant concentration,the value of dBs,kLa and kL decreased,while the value ofεand gas-liquid interfacial area(a)*** phenomena were mainly attributed to the synergistic effects of immobile bubble surface and the suppression of coalescence in the surfactant *** addition,with the presence of electric charge,MNBs in anionic surfactant solutions were smaller and higher in number than in non-ionic surfactant ***,the accumulation of surfactant on the gas-liquid interface was more conspicuous for small MNB,so the reduction of kL in anionic surfactant solutions was larger than that in non-ionic surfactant ***,the modified Frossling's model predicted the effect of surfactant on kL in MNB aeration system with reasonable accuracy.

关键词： soil flushing Micro-nano-bubble aeration Bio-surfactant Mass transfer coefficient

Mass transfer characteristics of chiral pharmaceuticals on membrane used for polar organic chemical integrative sampler

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Journal of Environmental sciences 2024年第2期136卷 670-681页

作者： Liyang Wang Ruixia liu Youya Zhou Peng yuan Xiaoling liu Hongjie Gao College of Water science Beijing Normal UniversityBeijing 100018China state Key Laboratory of Environmental Criteria and Risk Assessment Chinese Research Academy of Environmental ScienceBeijing 100012China Technical Centre for soil Agriculture and Rural Ecology and EnvironmentMinistry of Ecology and EnvironmentBeijing 100012China

Passive sampling technology has good application prospects for monitoring trace pollutants in aquatic *** research on the sampling mechanism of this technology is essential to improve the measurement accuracy and extend the application scope of this *** this s.udy,adsorption and permeation experiments were performed to investigate the sorption and mass transfer properties of five chiral pharmaceuticals at the enantiomeric level on polyethersulfone(PEs)and polytetrafluoroethylene(PTFE)membranes.used in a polar organic chemical integrative *** adsorption experiments showed that the PEs membrane had an adsorption phenomenon for most selected pollutants and an insignificant sorption behavior was observed for all selected pharmaceuticals on the PTFE membrane except for R(s)-*** diffusion coefficients of selected pharmaceuticals onto the PTFE membrane were approximately one order of magnitude higher than those onto the PEs *** permeation experiment indicated that under different hydraulic conditions,the change of the relative pollutant concentration through the PTFE membrane for the composite pollutant system was more obvious than that for the single pollutant system,and mass transfer hysteresis exists for both contaminant systems through PEs *** the first-order equation or 3-component model to estimate the overall mass transfer coefficients,the results showed that the overall mass transfer coefficient values of pollutants in the composite pollutant system onto both membranes were higher than those in the single pollutant *** parameter was mainly influenced by the synergistic effects of the multi-analyte interaction and diminished water boundary layers during the mass transfer process.

关键词： sorption phenomenon Permeation behavior Mass transfer properties Modeling calculation Chiral pharmaceuticals PEs and PTFE membrane

Performance Assessment and Improvement of Photovoltaic-Thermal system based on Energy,Exergy,Economic and Environment Analysis

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Journal of Thermal science 2024年第6期33卷 2166-2178页

作者： ZHOu yuan WANG Jiangjiang QIN Yanbo liu Boxiang Hebei Key Laboratory of Low Carbon and High Efficiency Power Generation Technology North China Electric Power University

A photovoltaic thermal（PV/T） system with parallel cooling channels was designed in this work to decrease the PV panel temperature and improve its photoelectric conversion efficiency.A 4E analysis method（includes energy,exergy,economic,and environmental aspects） was formulated to comprehensively evaluate the performances of the PV/T system,combining experimental and simulation ***,the experiment was performed using water as the cooling *** show that the PV/T system can reduce daily CO2emissions by 1682.47-1705.98 g,and compared to the PV system,the added cooling module can increase electrical efficiency and environmental performance by 12.19% and 6.2%,*** the mass flow of water rose from 0.017 kg/s to 0.023 kg/s,the electrical,thermal,and overall efficiencies were improved by 3.82%,11.36%,and 8.27%,***,a numerical simulation model was constructed based on the experimental results to predict operations of the presented PV/T system using nanofluids as the cooling medium,including Ag,Al2O3,and *** results show that the Al2O3-nanofluid-based PV/T system has a higher application value,enabling an electrical efficiency of up to 15.13%.Its thermal efficiency can be enhanced by5.43% when the volume fraction of Al2O3increases from 1% to 5%.

关键词： 4E analysis method nanofluid numerical analysis parallel cooling channels photovoltaic/thermal system

Tunable single emitter-cavity coupling strength through waveguide-assisted energy quantum transfer

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Light(science & Applications) 2024年第9期13卷 1779-1788页

作者： yuan liu Hongwei Zhou Linhan Lin Hong-Bo sun Department of Precision Instrument State Key Laboratory of Precision Measurement Technology and InstrumentsTsinghua UniversityBeijing 100084China state Key Laboratory of Integrated Optoelectronics College of Electronic Science and EngineeringJilin UniversityChangchun 130012China

The emitter-cavity strong coupling manifests crucial significance for exploiting quantum technology,especially in the scale of individual ***,due to the small light-matter interaction cross-section,the single emitter-cavity strong coupling has been limited by its harsh requirement on the quality factor of the cavity and the local density of optical ***,we present a strategy termed waveguide-assisted energy quantum transfer(WEQT)to improve the single emitter-cavity coupling strength by extending the interaction *** ancillary emitters are optically linked by a waveguide,providing an indirect coupling channel to transfer the energy quantum between target emitter and *** enhancement factor of coupling strength eg=g>10 can be easily achieved,which dramatically release the rigorous design of *** an extension of concept,we further show that the ancillae can be used as controlling bits for a photon gate,opening up new degrees of freedom in quantum manipulation.

关键词： quantum coupling transfer

CuIns_(2)quantum-dot-modified g-C_(3)N_(4)s-scheme heterojunction photocatalyst for hydrogen production and tetracycline degradation

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Journal of Materials science & Technology 2024年第5期172卷 145-155页

作者： Jingjing Zhang Yue Zhao Kezhen Qi s.u-yuan liu College of Pharmacy Dali UniversityDali 671000China Department of Pharmacology Shenyang Medical CollegeShenyang 110034China

CuIns_(2)quantum-dot(CIs QD)-modified g-C_(3)N_(4)(CN)catalysts(CIs/CN)were prepared with the aid of an in-situ growth *** as-obtained photocatalysts were explored by measuring their crystallinity,surface morphology,binding energy and light absorption *** photocatalytic efficiency of the pho-tocatalysts was evaluated through photocatalytic water splitting for hydrogen production and tetracycline(TC)antibiotic degradation under the simulated solar light and visible light *** optimized sample(10CIs/CN)showed the best photocatalytic activity:producing 102.4μmol g^(-1)h^(-1)of hydrogen in 1 h,or degrading 52.16%of TC in 120 min,which were respectively 48 or 3.4 times higher than the photocatalytic activity of CN *** enhancement in the efficiency of the composite system was prin-cipally accredited to the enlargement of light absorption,the more effective in charge transfer and the dropping of the charge carrier pair recombination through a formed s-scheme heterojunctional *** work is an effort to adjust CN-based polysulfide QD for speedy *** enriched photo-catalytic activity grants a new sense for adjusting the optical properties of CN.

关键词： CuIns_(2)QDs g-C_(3)N_(4) Photocatalysis Hydrogen production s-scheme heterojunction

Comparison of irradiation-induced void formations in tungsten with equiaxed and columnar structures

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Tungsten 2024年第4期6卷 794-805页

作者： liu Xi Jia-Jun Zhao Ji-Jun Zhao yuan-yuan Wang Key Laboratory of Materials Modification by Laser Ion and Electron Beams(Ministry of Education) Dalian University of Technology

Tungsten(W) has been received much attention,since it is regarded as one of the most promising plasma facing materials for fusion *** are two typical morphologies of unirradiated polycrystalline W,which have the equiaxed and columnar grains,***,the role of arrangement of grain boundary(GB) in absorbing irradiation-generated point defects is still waiting to be *** current investigation,irradiation-induced void formations in W with equiaxed and columnar microstructures are predicted,respectively,using the developed phase-field *** significant kinetic behavior,such as the generation and annihilation of point defects and the interaction between point defects and GB,is reasonably *** density,size and porosity of void formed in these two microstructures are examined and analyzed according to the effects of GB ratio,temperature and damage *** analytical results show that higher GB ratio can effectively reduce void porosity,and the columnar-grained structure has better irradiation resistance than that of the equiaxed one in the case of small grain *** importantly,the predicted void sizes changed with temperature and damage rate agree well with the experimentally measured *** work has a more beneficial contribution to the microstructural improvement of International Thermonuclear Experimental Reactor-grade W.

关键词： Grain morphology Irradiation-induced void Phase-field Tungsten

An Efficient Radar Detection Method of Maneuvering small Targets

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Journal of Beijing Institute of Technology 2024年第1期33卷 1-8页

作者： Hongchi Zhang yuan Feng shengheng liu school of Information and Electronics Beijing Institute of Technology and Beijing Key Laboratory of Fractional Signals and SystemsBeijing 100081China school of Information science and Engineering Southeast UniversityNanjing 210096China

Detection of maneuvering small targets has always been an important yet challenging task for radar signal *** primary reason is that target variable motions within coherent processing interval generate energy migrations across multiple resolution bins,which severely deteriorate the parameter estimation performance.A coarse-to-fine strategy for the detection of maneuvering small targets is *** of small points segmented coherently is performed first,and then an optimal inter-segment integration is.utilized to derive the coarse estimation of the chirp *** fractional Fourier transform(FrFT)is then employed to refine the coarse estimation at a significantly reduced computational *** results verify the proposed scheme that achieves an efficient and reliable maneuvering target detection with-16dB input signal-to-noise ratio(sNR),while requires no exact a priori knowledge on the motion parameters.

关键词： small target chirp sparse fractional Fourier transform(FrFT)

Enhancing ionic conductivity of garnet-type Nb-doped Li_(7)La_(3)Zr_(2)O_(12)by cerium doping

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Journal of Rare Earths 2024年第9期42卷 1740-1746,I0004页

作者： Daming liu yuan Hou Chaoke Bulin Ruichao Zhao Bangwen Zhang Analytical and Testing Center Inner Mongolia University of Science and TechnologyBaotou014010China school of Materials and Metallurgy Inner Mongolia University of Science and TechnologyBaotou014010China school of Metallurgy and Materials Engineering Chongqing University of Science and TechnologyChongqing401331China

We investigated the effect of additional doping with Ce on the ionic conductivity of the Nb-doped Li_(7)La_(3)Zr_(2)O_(12)(LLZO)garnet ceramics.using a combination of experimental and modeling *** results indicate that Ce doping can alter lattice parameters of the LLZNO,leading to the enhanced lithium ionic *** Ce,Nb co-doped LLZO(LLZNCO)structure with composition Li_(6.5)La_(3)Zr_(1.5-x)Nb_(0.5)Ce_(x)O_(12)(x=0.125)exhibits a lower activation energy(E_(a)=0.39 eV)than Li_(6.5)La_(3)Zr_(1.5)Nb_(0.5)O_(12)(LLZNO)(E_(a)=0.41 eV).Furthermore,Ce doping leads to an increase in Li~+conductivity from 6.4×10^(-4)to 7×10^(-4)s/cm at room *** addition,we dis.uss the diffusivity and conductivity of our samples.using ab initio molecular dynamics simulations and propose possible mechanisms to explain the enhanced Li-ion conductivity caused by co-doping with Ce and *** results demonstrate that the LLZNCO ceramics are promising candidates for potential solid-state electrolytes for Li-ion batteries.

关键词： Rare earths solid state electrolyte Ionic conductivity Doping