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Divergence-Free Virtual Element Method for the Stokes Equations with Damping on Polygonal Meshes

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NUMERICAL MATHEMATICS-THEORY METHODS AND APPLICATIONS 2024年第1期17卷 210-242页

作者： Xiong, yu Chen, Yanping Zhou, Jianwei Liang, qin Xiangtan Univ Sch Math & Computat Sci Hunan Key Lab Computat & Simulat Sci & Engn Xiangtan 411105 Peoples R China Linyi Univ Sch Math & Stat Linyi 276005 Peoples R China South China Normal Univ Sch Math Sci Guangzhou 510631 Peoples R China

In this paper, we construct, analyze, and numerically validate a family of divergence-free virtual elements for Stokes equations with nonlinear damping on polygonal meshes. The virtual element method is H1-conforming and exact divergence-free. By virtue of these properties and the topological degree argument, we rigorously prove the well-posedness of the proposed discrete scheme. The convergence analysis is carried out, which imply that the error estimate for the velocity in energy norm does not explicitly depend on the pressure. Numerical experiments on various polygonal meshes validate the accuracy of the theoretical analysis and the asymptotic pressure robustness of the proposed scheme.

关键词： Optimal error estimates divergence-free virtual element nonlinear damping term DISCONTINUOUS GALERKIN METHODS EXISTENCE DARCY WEAK PROJECTORS

Heterogeneous MXene-based films with graded electrical conductivity towards highly efficient EMI shielding and electrothermal heating

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Nano Research 2024年第8期17卷 7264-7274页

作者： yu Zhang Guangcheng Zhang Zhonglei Ma Jianbin qin Xi Shen Department of Aeronautical and Aviation Engineering The Hong Kong Polytechnic UniversityHung HomKowloonHong KongChina Shaanxi Key Laboratory of Macromolecular Science and Technology School of Chemistry and Chemical EngineeringNorthwestern Polytechnical UniversityXi’an 710072China Research Institute for Sports Science and Technology The Hong Kong Polytechnic UniversityHung HomKowloonHong KongChina

The increasing need for electromagnetic interference(EMI)shielding of electronics in cold environments such as those in aircraft,space exploration,and wearable heaters to avoid hazardous icing conditions or hypothermia requires the development of thin and lightweight EMI shielding materials preferably by absorbing rather than reflecting electromagnetic(EM)waves while also generating heat through energy-efficient electrothermal ***,it is challenging to achieve absorption-dominant EMI shielding and energy-efficient electrothermal heating simultaneously in a thin and lightweight ***,we develop a heterogeneous composite film comprising a porous multi-walled carbon nanotubes(MWCNTs)/bacterial cellulose(BC)film and an aligned MXene/Ag nanowires(NWs)backing via a sequential vacuum filtration *** porous film contains random conductive networks of MWCNTs with moderate conductivity while the aligned MXene sheets atop Ag NWs network affords high conductivity in the backing,giving rise to graded electrical conductivity for absorption-dominant EMI *** increasing Ag NW coverage leads to significantly increased electrical conductivity without increasing the EM wave reflection as well as the density and thickness of the film,yielding excellent specific EMI shielding effectiveness(>8500 dB/(g·cm^(2))),low driving voltage for energy-efficient electrothermal heating(163℃at 2.5 V),and fast response time(60 s)at a low areal density of 0.015 mg/cm^(2).Combining EMI shielding and electrothermal heating,the heterogeneous film developed here are promising contenders for the protection of electronic equipment in low-temperature environment.

关键词： heterogenous composite film MXene electromagnetic interference(EMI)shielding thermal management

Left atrial appendage occluder detachment treated with transthoracic ultrasound combined with digital subtraction angiography guided catcher:A case report

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World Journal of Clinical Cases 2024年第6期12卷 1157-1162页

作者： Kai yu yun-Hua mei Department of Ultrasound Wuhan Dongxihu District People's HospitaWuhan 430400Hubei ProvinceChina Department of Infectious Diseases Wuhan Dongxihu District People's HospitalWuhan 430400Hubei ProvinceChina

BACKGROUND There are very few cases of cardiac occluder detachment,and it is rare to completely remove the occluder using interventional methods without undergoing thoracotomy surgery after *** case innovatively used ultrasound guidance combined with digital subtraction angiography(DSA)to completely remove the occluder,accumulating some *** SUMMARY The patient underwent left atrial appendage occlusion surgery in our hospital due to atrial *** the surgery,the occluder fell off and became free in the left ventricle,which is very *** innovatively used ultrasound guidance,combined with DSA,and interventional surgery to successfully capture the free occluder using a catcher,completely remove it,and then re implant a new left atrial appendage *** the surgery,the patient recovered very *** The size selection of the occluder is slightly conservative,and the shape of the left atrial appendage opening is irregular.

关键词： Left atrial appendage occluder Detachment Ultrasound combined with digital subtraction angiography Interventional operation Successfully captured Case report

Effect of safety valve types on the gas venting behavior and thermal runaway hazard severity of large-format prismatic lithium iron phosphate batteries

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Journal of Energy Chemistry 2024年第2期89卷 195-207,I0006页

作者： Zhuangzhuang Jia yuanyuan Min Peng qin Wenxin mei Xiangdong Meng Kaiqiang Jin Jinhua Sun qingsong Wang State Key Laboratory of Fire Science University of Science and Technology of ChinaHefei 230026AnhuiChina Gotion High-Tech Co. Ltd.Hefei 230012AnhuiChina

The safety valve is an important component to ensure the safe operation of lithium-ion batteries(LIBs).However,the effect of safety valve type on the thermal runaway(TR)and gas venting behavior of LIBs,as well as the TR hazard severity of LIBs,are not *** this paper,the TR and gas venting behavior of three 100 A h lithium iron phosphate(LFP)batteries with different safety valves are investigated under *** to previous studies,the main contribution of this work is in studying and evaluating the effect of gas venting behavior and TR hazard severity of LFP batteries with three safety valve *** significant results are obtained:(Ⅰ)the safety valve type dominates over gas venting pressure of battery during safety venting,the maximum gas venting pressure of LFP batteries with a round safety valve is 3320 Pa,which is one order of magnitude higher than other batteries with oval or cavity safety valve;(Ⅱ)the LFP battery with oval safety valve has the lowest TR hazard as shown by the TR hazard assessment model based on gray-fuzzy analytic hierarchy *** study reveals the effect of safety valve type on TR and gas venting,providing a clear direction for the safety valve design.

关键词： Lithium iron phosphate battery Safety valve Thermal runaway Gas venting behavior Thermal runaway hazard severity Gray-fuzzy analytic hierarchy process

An AIEgen nano-assembly for simultaneous detection of ATP and H_(2)S

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Chinese Chemical Letters 2024年第6期35卷 376-379页

作者： Jia-mei qin Xue Li Wei Lang Fu-Hao Zhang Qian-Yong Cao School of Chemistry and Chemical Engineering Nanchang UniversityNanchang 330031China

A new aggregation-induced emission(AIE)-based fluorescence sensor,TPEPy-SS-C14,for simultaneous recognition of adenosine triphosphate(ATP)and hydrogen sulfide(H_(2)S)has been reported via the aggregation-disaggregation *** probe self-assembles nano-structure aggregations in aqueous *** shows fluorescence turn-on response toward ATP for the complexation-enhanced aggregation,but leads to fluorescence quenching of H_(2)S for cleavage the aggregations.

关键词： AIE-based ATP detection H_(2)S detection Fluorescent sensor Cell imaging

Correlation between Combined Urinary Metal Exposure and Grip Strength under Three Statistical Models:A Cross-sectional Study in Rural Guangxi

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Biomedical and Environmental Sciences 2024年第1期37卷 3-18页

作者： LIANG yu Jian RONG Jia Hui WANG Xue Xiu CAI Jian Sheng qin Li Dong LIU Qiu mei TANG Xu MO Xiao Ting WEI Yan Fei LIN Yin Xia HUANG Shen Xiang LUO Ting yu GOU Ruo yu CAO Jie Jing HUANG Chu Wu LU yu Fu qin Jian ZHANG Zhi Yong Department of Environmental and Occupational Health School of Public HealthGuangxi Medical UniversityNanning 530021GuangxiChina Key Laboratory of Tumor Immunology and Microenvironmental Regulation Guilin Medical UniversityGuilin 541199GuangxiChina Department of Environmental Health and Occupational Medicine School of Public HealthGuilin Medical UniversityGuilin 541199GuangxiChina Guangxi Colleges and Universities Key Laboratory of Prevention and Control of Highly Prevalent Diseases Guangxi Medical UniversityNanning 530021GuangxiChina Guangxi Key Laboratory of Environment and Health Research Guangxi Medical UniversityNanning 530021GuangxiChina Key Laboratory of Longevity and Aging-related Diseases of Chinese Ministry of Education Guangxi Medical UniversityNanning 530021GuangxiChina Guangxi Health Commission Key Laboratory of Entire Lifecycle Health and Care Guilin Medical UniversityGuilin 541199GuangxiChina

Objective This study aimed to investigate the potential relationship between urinary metals copper(Cu),arsenic(As),strontium(Sr),barium(Ba),iron(Fe),lead(Pb)and manganese(Mn)and grip *** We used linear regression models,quantile g-computation and Bayesian kernel machine regression(BKMR)to assess the relationship between metals and grip *** In the multimetal linear regression,Cu(β=−2.119),As(β=−1.318),Sr(β=−2.480),Ba(β=0.781),Fe(β=1.130)and Mn(β=−0.404)were significantly correlated with grip strength(P<0.05).The results of the quantile g-computation showed that the risk of occurrence of grip strength reduction was−1.007(95%confidence interval:−1.362,−0.652;P<0.001)when each quartile of the mixture of the seven metals was *** kernel function regression model analysis showed that mixtures of the seven metals had a negative overall effect on grip strength,with Cu,As and Sr being negatively associated with grip strength *** the total population,potential interactions were observed between As and Mn and between Cu and Mn(P_(interactions) of 0.003 and 0.018,respectively).Conclusion In summary,this study suggests that combined exposure to metal mixtures is negatively associated with grip ***,Sr and As were negatively correlated with grip strength levels,and there were potential interactions between As and Mn and between Cu and Mn.

关键词： Urinary metals Handgrip strength Quantile g-computation Bayesian kernel machine regression

Detecting bulk and edge exceptional points in non-Hermitian systems through generalized Petermann factors

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Frontiers of physics 2024年第2期19卷 169-177页

作者： yue-yu Zou Yao Zhou Li-mei Chen Peng Ye School of Physics State Key Laboratory of Optoelectronic Materials and Technologiesand Guangdong Provincial Key Laboratory of Magnetoelectric Physics and DevicesSun Yat-sen UniversityGuangzhou 510275China

Non-orthogonality in non-Hermitian quantum systems gives rise to tremendous exotic quantum phenomena,which can be fundamentally traced back to *** this paper,we introduce an interesting quantity(denoted asη)as a new variant of the Petermann factor to directly and efficiently measure non-unitarity and the associated non-Hermitian *** tuning the model parameters of underlying non-Hermitian systems,we find that the discontinuity of bothηand its first-order derivative(denoted as■η)pronouncedly captures rich physics that is fundamentally caused by *** concretely,in the 1D non-Hermitian topological systems,two mutually orthogonal edge states that are respectively localized on two boundaries become non-orthogonal in the vicinity of discontinuity ofηas a function of the model parameter,which is dubbed"edge state transition".Through theoretical analysis,we identify that the appearance of edge state transition indicates the existence of exceptional points(EPs)in topological edge *** the discontinuity of■η,we investigate a two-level non-Hermitian model and establish a connection between the points of discontinuity of■ηand EPs of bulk *** studying this connection in more general lattice models,we find that some models have discontinuity of■η,implying the existence of EPs in bulk states.

关键词： non-Hermitian Su−Schrieffer−Heeger(SSH)model exceptional point

The new challenges for the development of NH_(3)-SCR catalysts under new situation of energy transition in power generation industry

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Chinese Chemical Letters 2024年第6期35卷 95-103页

作者： Feibin Wei Yongfang Rao yu Huang Wei Wang Hui mei Science and Technology on Thermostructural Composite Materials Laboratory School of Materials Science and EngineeringNorthwestern Polytechnical UniversityXi’an 710072China Key Laboratory of Aerosol Chemistry and Physics State Key Laboratory of Loess and Quaternary Geology(SKLLQG)Institute of Earth EnvironmentChinese Academy of SciencesXi’an 710061China Center of Excellence in Quaternary Science and Global Change Chinese Academy of SciencesXi’an 710061China University of Chinese Academy of Sciences Beijing 100049China Department of Environmental Science and Engineering Xi’an Jiaotong UniversityXi’an 710049China

NH_(3)-SCR was one of the most promising de NO_x technologies and it has been widely applied in industrial NO_x ***,with the further development of energy transformation in power generation sector,the development of NH_(3)-SCR catalysts is facing some new *** is becoming an urgent problem to solve low catalytic activity and stability of NH_(3)-SCR catalysts at the working condition of ultra-low temperature(≤200℃)and high concentrations of H_(2)O+SO_(2) due to the gradual deployment of new energy power ***,the traditional coal-fired power plants would need flexible operation with the increasing share of renewable energy *** NH_(3)-SCR catalysts which were applied in coal-fired power industry would be requested to work in a wide temperature window from 200℃ to 500℃ in the near ***,in this review,we summarized the progress of NH_(3)-SCR catalysts in solving these different industrial problems in recent *** the research directions which were deserved to be focused on the development of NH_(3)-SCR catalysts for the energy transition of power generation sector are proposed.

关键词： NH_(3)-SCR NOx reduction Power generation Ultra-low temperature Wide temperature windows

Resolution Enhancement of SOHO/MDI Magnetograms

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Research in Astronomy and Astrophysics 2024年第6期24卷 358-367页

作者： Ying qin Kai-Fan Ji Hui Liu Xiao-Guang yu yunnan Observatories Chinese Academy of SciencesKunming 650011China University of Chinese Academy of Sciences Beijing 100049China yunnan Key Laboratory of Solar Physics and Space Science Kunming 650216China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of SciencesKunming 650216China

Research on the solar magnetic field and its effects on solar dynamo mechanisms and space weather events has benefited from the continual improvements in instrument resolution and measurement *** augmentation and assimilation of historical observational data timelines also play a significant role in understanding the patterns of solar magnetic field *** the realm of astronomical data processing,super-resolution(SR)reconstruction refers to the process of using a substantial corpus of training data to learn the nonlinear mapping between low-resolution(LR)and high-resolution(HR)images,thereby achieving higherresolution astronomical *** paper is an application study in high-dimensional nonlinear *** learning models were employed to perform SR modeling on SOHO/MDI magnetograms and SDO/HMI magnetograms,thus reliably achieving resolution enhancement of full-disk SOHO/MDI magnetograms and enhancing the image resolution to obtain more detailed *** this study,a data set comprising 9717pairs of data from 2010 April to 2011 February was used as the training set,1332 pairs from 2011 March were used as the validation set and 1034 pairs from 2011 April were used as the test *** data preprocessing,we randomly cropped 128×128 sub-images as the LR cases from the full-disk MDI magnetograms,and the corresponding 512×512 sub-images as HR ones from the HMI full-disk magnetograms for model *** tests conducted have shown that the study successfully produced reliable 4×SR reconstruction of full-disk MDI *** MESR model's results(0.911)were highly correlated with the target HMI magnetographs as indicated by the correlation coefficient ***,the method achieved the best PSNR,SSIM,MAE and RMSE values,indicating that the MESR model can effectively reconstruct magnetograms.

关键词： magnetic fields techniques:image processing virtual observatory tools Sun:magnetic fields