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A stable staggered-grid finite-difference scheme for acoustic modeling beyond conventional stability limit

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Petroleum Science 2024年第1期21卷 182-194页

作者： Jing-Yi Xu yang liu National Key Laboratory of Petroleum Resources and Engineering China University of Petroleum(Beijing)Beijing 102249China China University of Petroleum(Beijing) Karamay CampusKaramay 834000XinjiangChina

Staggered-grid finite-difference(SGFD)schemes have been widely used in acoustic wave modeling for geophysical *** improved methods are proposed to enhance the accuracy of numerical ***,these methods are inevitably limited by the maximum Courant-Friedrichs-Lewy(CFL)numbers,making them unstable when modeling with large time sampling intervals or small grid *** solve this problem,we extend a stable SGFD scheme by controlling SGFD dispersion relations and maximizing the maximum CFL ***,to improve modeling stability,we minimize the error between the FD dispersion relation and the exact relation in the given wave-number region,and make the FD dispersion approach a given function outside the given wave-number area,thus breaking the conventional limits of the maximum CFL ***,to obtain high modeling accuracy,we use the SGFD scheme based on the Remez algorithm to compute the FD *** addition,the hybrid absorbing boundary condition is adopted to suppress boundary reflections and we find a suitable weighting coefficient for the proposed *** derivation and numerical modeling demonstrate that the proposed scheme can maintain high accuracy in the modeling process and the value of the maximum CFL number of the proposed scheme can exceed that of the conventional SGFD scheme when adopting a small maximum effective wavenumber,indicating that the proposed scheme improves stability during the modeling.

关键词： Acoustic wave Staggered-grid finite-difference(SGFD) modeling Courant-friedrichs-lewy(CFL)number Stability

Precise measurement of geometric and physical quantities in cutting tools inspection and condition monitoring: A review

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Chinese Journal of Aeronautics 2024年第4期37卷 23-53页

作者： Wenqi WANG Wei liu yang ZHANG yang liu Peidong ZHANG Zhenyuan JIA State Key Laboratory of High-Performance Precision Manufacturing Dalian University of TechnologyDalian 116024China

As one of the most important terminals in machining, cutting tools have been widely used for components manufacturing in aerospace and other industries. The quality of these components and processing efficiency are closely linked to the performance of cutting tools. Therefore, it is essential and critical to inspect the cutting tools and monitor the condition during the stage of manufacturing and machining. This review aims to discuss and summarize the key problems, methods,and techniques from the perspective of the tool geometric and the physical quantities measurement,including machine vision, physical sensors and data processing. It is worth mentioning that we focus on the topic of precision measurement methods and discuss universal solutions by identifying the common characteristics of the measured quantities. Eventually, the challenges and future trends for the development of in-depth research and practical applications are concluded. The research and application of precise measurement techniques for geometric and physical quantities will better promote the development of intelligent manufacturing.

关键词： Cutting tools Mechanical measurement Machine vision Physical sensors Tool condition monitoring

Characteristics of bioaerosols under high-ozone periods,haze episodes,dust storms,and normal days in Xi'an,China

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Particuology 2024年第7期90卷 140-148页

作者： Yiming yang liu yang Xiaoyan Hu Zhenxing Shen Department of Environmental Science and Engineering Xi’an Jiaotong UniversityXi’an710049China Key Lab of Aerosol Chemistry&Physics SKLLQGInstitute of Earth EnvironmentChinese Academy of SciencesXi’an710049China

The characteristics of bioaerosols and their effects on human beings'health have become a major public concern in the recent *** study compared the characteristics of bioaerosols under different types of pollution(high-ozone[HO]episodes,haze episodes,and dust storms[DSs]),with those of bioaerosols on normal days(NDs)in Xi'an,*** concentrations,diurnal variations,and size distribution of bacteria,fungi,and total airborne microbes(TAMs)were *** results showed that the bacterial and fungal concentrations were the highest during DSs and on NDs,reaching 425.2 and 956.9 colony-forming units/m^(3),*** concentration of TAMs was the highest during HO episodes,reaching 10.7×10^(6)cells/m^(3),which was significantly higher than that during the other *** maximum concentrations of bacteria and fungi during HO episodes were observed in the morning,while they appeared separately in the morning and evening during haze *** and TAMs during DSs reached peak concentrations in the morning and evening,which is opposite to the particulate matter(PM)distribution *** NDs,temperature and relative humidity had significant effects on *** size distributions of airborne bacteria exhibited bimodal patterns,whereas unimodal distributions were observed for *** mainly attached in fine particles(<2.1μm)with proportions of 67.4%and 60.5%during haze episodes and DSs,respectively,which means that fungi were easily penetrated into the human respiratory *** evaluation of influence factors revealed that PM_(2.5) and PM10 had negative effects on fungal concentration during DSs,and ozone concentration and temperature were inversely correlated with fungal concentration during HO *** results provide valuable reference data for elucidating the formation and evolution of bioaerosols under different types of pollution.

关键词： Bacteria Fungi Total airborne microbe Different air pollution types Influence factors

Recent advances in phenazine-linked porous catalysts toward photo/electrocatalytic applications and mechanism

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Green Energy & Environment 2024年第10期9卷 1518-1549页

作者： yang liu Yu Zhang Zhao-Di yang Liqiang Jing Heilongjiang Provincial Key Laboratory of CO2 Resource Utilization and Energy Catalytic Materials School of Material Science and Chemical EngineeringHarbin University of Science and Technology Institute of Process Engineering Chinese Academy of Sciences Key Laboratory of Functional Inorganic Materials Chemistry(Ministry of Education) School of Chemistry and Materials Science International Joint Research Center for Catalytic Technology Heilongjiang University

In recent years, porous organic catalysts have been developed and become research hotspots in photo/electrocatalysis due to their inherent pores, high specific surface area, chemical and thermal stability, and diverse functional building blocks. Phenazine-linked organic catalysts,exhibited excellent conjugation, electrical conductivity, chemical, and thermal stability, could bring in N atoms with specific numbers and positions to regulate electron levels, anchor metals, and absorb near-infrared light, which expands solar energy utilization. These advantages of the phenazine-linked catalysts attracted our group and numerous researchers to conduct experimental and computational work on photo/electrocatalytic applications and mechanisms. This review summarizes the recent significant research progress, synthesis methods, photo/electrocatalytic performance, and applications of relative phenazine-linked catalysts. Furthermore, the photo/electrocatalytic mechanism was systematized and summarized by combining experiments and density functional theory calculations simultaneously.

关键词： Phenazine-linked porous catalysts Photo/electrocatalytic applications Catalytic mechanism

Exosomal let-7a-5p derived from human umbilical cord mesenchymal stem cells alleviates coxsackievirus B3-induced cardiomyocyte ferroptosis via the SMAD2/ZFP36 signal axis

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Journal of Zhejiang University-Science B(Biomedicine & Biotechnology) 2024年第5期25卷 422-437页

作者： Xin LI Yanan HU Yueting WU Zuocheng yang yang liu Hanmin liu Department of Pediatric Pulmonology and Immunology West China Second University HospitalSichuan UniversityChengdu 610041China Key Laboratory of Birth Defects and Related Diseases of Women and Children(Sichuan University) Ministry of EducationChengdu 610041China NHC Key Laboratory of Chronobiology(Sichuan University) Chengdu 610041China The Joint Laboratory for Lung Development and Related Diseases of West China Second University Hospital Sichuan University and School of Life Sciences of Fudan UniversityWest China Institute of Women and Children's HealthWest China Second University HospitalSichuan UniversityChengdu 610041China Sichuan Birth Defects Clinical Research Center West China Second University HospitalSichuan UniversityChengdu 610041China Department of Pediatrics the Third Xiangya HospitalCentral South UniversityChangsha 410013China

Viral myocarditis(VMC)is one of the most common acquired heart diseases in children and ***,its pathogenesis is still unclear,and effective treatments are *** study aimed to investigate the regulatory pathway by which exosomes alleviate ferroptosis in cardiomyocytes(CMCs)induced by coxsackievirus B3(CVB3).CVB3 was utilized for inducing the VMC mouse model and cellular *** echocardiography,left ventricular ejection fraction(LVEF),and left ventricular fractional shortening(LVFS)were implemented to assess the cardiac *** CVB3-induced VMC mice,cardiac insufficiency was observed,as well as the altered levels of ferroptosis-related indicators(glutathione) peroxidase 4(GPX4),glutathione(GSH),and malondialdehyde(MDA).However,exosomes derived from human umbilical cord mesenchymal stem cells(hucMSCs-exo)could restore the changes caused by CVB3 ***-7a-5p was enriched in hucMSCs-exo,and the inhibitory ffect of hucMSCs-exoa-ie-pmimo on CVB3-induced ferroptosis was higher than that of hucMSCs-exommie N(NC:negative control).Mothers against decapentaplegic homolog 2(SMAD2)increased in the VMC group,while the expression of zinc-finger protein 36(ZFP36)***-7a-5p was confirmed to interact with SMAD2 messenger RNA(mRNA),and the SMAD2 protein interacted directly with the ZFP36 *** SMAD2 and overexpressing ZFP36 inhibited the expression of ferroptosis-related ***,the levels of GPX4,solute carrier family 7,member 11(SLC7A11),and GSH were lower in the SMAD2 overexpression plasmid(oe-SMAD2)+let-7a-5p mimic group than in the oe-NC+let-7a-5p mimic group,while those of MDA,reactive oxygen species(ROS),and Fe^(2+)*** conclusion,these data showed that ferroptosis could be regulated by mediating SMAD2 ***-let-7a-5p derived from hucMSCs could mediate SMAD2 to promote the expression of ZFP36,which further inhibited the ferroptosis of CMCs to alleviate CVB3-induced VMC.

关键词： Exosome Let-7a-5p Mothers against decapentaplegic homolog 2(SMAD2) Coxsackievirus B3(CVB3) Ferroptosis

Divalent anion intercalation and etching-hydrolysis strategies to construct ultra-stable electrodes for seawater splitting

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Science China Chemistry 2024年第2期67卷 687-695页

作者： Jiajia Lu yang liu Han-Pu Liang Key Laboratory of Biofuels Qingdao Institute of Bioenergy and Bioprocess TechnologyChinese Academy of SciencesQingdao266101China Henan Provincial Key Laboratory of Nanocomposites and Applications Institute of Nano-Structured Functional MaterialsHuanghe Science and Technology CollegeZhengzhou450006China School of Materials Science and Engineering Henan Normal UniversityXinxiang453007China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing100049China Shandong Energy Institute Qingdao266101China

Developing stable electrodes for seawater splitting remains a great challenge due to the detachment of catalysts at a large operating current and severe anode corrosion caused by ***,divalent anion intercalation and etching-hydrolysis strategies are deployed to synthesize the ultra-stable anode,dendritic Fe(OH)_(3) grown on Ni(SO_4)_(0.3)(OH)_(1.4)–Ni(OH)_(2).Experimental results reveal that the anode exhibits good activity and excellent stability in alkaline simulated *** 500 h,the current density operated at 1.72 V remains 99.5%,about 210 m A cm^(-2).The outstanding stability originates from the etchinghydrolysis strategy,which strengthens the interaction between the catalyst and the carrier and retards thus the detachment of catalysts at a large current ***,theoretical simulations confirm that the intercalated divalent anions,such as SO_4^(2-) and CO_(3)^(2-),can weaken the adsorption strength of chlorine on the surface of catalysts and hinder the coupling and hybridization between chlorine and nickel,which slows down the anode corrosion and improves catalytic ***,the twoelectrode system shows the remarkable 95.1% energy efficiency at 2,000 A m-2and outstanding stability in 6 mol L^(-1) KOH +seawater at 80 ℃.

关键词： seawater splitting stability divalent anion intercalation etching-hydrolysis

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Transition metal clusters with precise numbers of atoms anchored on graphdiyne as multifunctional electrocatalysts for OER/ORR/HER:a computational study

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Rare Metals 2024年第7期43卷 3107-3117页

作者： Xin-yang liu Jing-Wei liu Gang Li Jing-Xiang Zhao College of Chemistry and Chemical Engineering Harbin Normal UniversityHarbin 150025China

Subnanometer metal clusters play an increasingly important role in heterogeneous catalysis due to their high catalytic activity and *** this work,by means of the density functional theory(DFT) calculations,the catalytic activities of transition metal clusters with precise numbers of atoms supported on graphdiyne(TM_(1-4)@GDY,TM=V,Cr,Mn,Fe,Co,Ni,Cu,Ru,Rh,Pd,Ir,Pt) were investigated for oxygen evolution reactions(OER),oxygen reduction reactions(ORR) and hydrogen evolution reactions(HER).The computed results reveal that the Pd_(2),Pd_(4) and Pt_(1) anchored graphdiyne can serve as trifunctional catalysts for OER/ORR/HER with the overpotentials of 0.49/0.37/0.06,0.45/0.33/0.12 and 0.37/0.43/0.01 V,respectively,while Pd_(1) and Pt_(2)@graphdiyne can exhibit excellent catalytic performance for water splitting(OER/HER) with the overpotentials of 0.55/0.17 and 0.43/0.03 *** addition,Ni_(1) and Pd_(3) anchored GDY can perform as bifunctional catalysts for metal-air cells(OER/ORR) and fuels cells(ORR/HER) with the overpotentials of 0.34/0.32 and 0.42/0.04 V,***,by precisely controlling the numbers of atoms in clusters,the TM_(1-4) anchored graphdiyne can serve as promising multifunctional electrocatalysts for OER/ORR/HER,which may provide an instructive strategy to design catalysts for the energy conversation and storage devices.

关键词： Density functional theory Graphdiyne Single-cluster catalysts Multifunctional electrocatalysts Overpotential

A Correlation-Based Stochastic Model for Massive MIMO Channel

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China Communications 2024年第1期21卷 175-187页

作者： yang liu Gang Li Chengxiang Wang National Mobile Communications Research Laboratory School of Information Science and EngineeringSoutheast UniversityNanjing 211189China School of Internet of Things Engineering Jiangnan UniversityWuxi 214122China Pervasive Communication Research Center Purple Mountain LaboratoriesNanjing 211111China

In this paper,the channel impulse response matrix(CIRM)can be expressed as a sum of couplings between the steering vectors at the base station(BS)and the eigenbases at the mobile station(MS).Nakagami distribution was used to describe the fading of the coupling between the steering vectors and the *** measurements were carried out to evaluate the performance of this proposed ***,the physical implications of this model were illustrated and the capacities are *** addition,the azimuthal power spectrum(APS)of several models was ***,the channel hardening effect was simulated and *** showed that the proposed model provides a better fit to the measured results than the other CBSM,i.e.,Weichselberger ***,the proposed model can provide better tradeoff between accuracy and complexity in channel *** CIRM model can be used for massive MIMO design in the future communication system design.

关键词： CBSM channel capacity channel hardening channel modeling massive MIMO

On the Probability of Generating a Primitive Matrix

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Journal of Systems Science & Complexity 2024年第4期37卷 1755-1771页

作者： CHEN Jingwei FENG Yong liu yang WU Wenyuan Chongqing Key Laboratory of Automated Reasoning and Cognition Chongqing Institute of Green and Intelligent TechnologyChinese Academy of SciencesChongqing 400714China Chongqing College University of Chinese Academy of SciencesChongqing 400714China Key Laboratory of Advanced Manufacturing Technology of Ministry of Education Guizhou UniversityyGuiyang 550025China Information Science and Engineering Chongqing Jiaotong UniversityChongqing 400074China

Given a k×n integer primitive matrix A(i.e.,a matrix can be extended to an n×n unimodular matrix over the integers)with the maximal absolute value of entries‖A‖bounded by an integer λ from above,the authors study the probability that the m×n matrix extended from A by appending other m-k row vectors of dimension n with entries chosen randomly and independently from the uniform distribution over{0,1,…,λ-1}is still *** authors present a complete and rigorous proof of a lower bound on the probability,which is at least a constant for fixed m in the range[k+1,n-4].As an application,the authors prove that there exists a fast Las Vegas algorithm that completes a k×n primitive matrix A to an n×n unimodular matrix within expected O(n^(ω)log‖A‖)bit operations,where O is big-O but without log factors,ω is the exponent on the arithmetic operations of matrix multiplication.

关键词： Integer matrix matrix completion probabilistic algorithm unimodular matrix