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A polynomial resultant approach to algebraic constructions of extremal graphs

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Science China Mathematics 2024年

作者： Tao Zhang Zixiang Xu Gennian Ge institute of Mathematics and Interdisciplinary sciences Xidian University School of mathematical sciences Capital Normal University

The Turan problem asks for the largest number of edges ex（n, H） in an n-vertex graph not containing a fixed forbidden subgraph H, which is one of the most important problems in extremal graph theory. However,the order of magnitude of ex（n, H） for bipartite graphs is known only in a handful of cases. In particular,giving explicit constructions of extremal graphs is very challenging in this field. In this paper, we develop a polynomial resultant approach to the algebraic construction of explicit extremal graphs, which can efficiently decide whether a specified structure exists. A key insight in our approach is the multipolynomial resultant, which is a fundamental tool of computational algebraic geometry. Our main results include the matched lower bounds on the Turan number of 1-subdivision of K3,t1and the linear Turan number of the Berge theta hypergraphΘ3B,t2, where t1= 25 and t2= 217. Moreover, the constant t1 improves the random algebraic construction of Bukh and Conlon（2018） and makes the known estimation better on the smallest value of t1 concerning a problem posed by Conlon et al.（2021） by reducing the value from a magnitude of 1056 to the number 25, while the constant t2improves a result of He and Tait（2019）.

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青藏高原地表变暗与北极气候变化间的共振

Science Bulletin 2024年第3期69卷 367-374页

作者：汤舒畅朴世龙 David M.Holland 阚飞汪涛姚檀栋李熙晨 Sino-French institute for Earth System Science College of Urban and Environmental SciencesPeking UniversityBeijing 100871China State Key Laboratory of Tibetan Plateau Earth System Resources and EnvironmentInstitute of Tibetan Plateau ResearchChinese Academy of SciencesBeijing 100085China courant institute of mathematical sciences New York UniversityNew YorkNY 0711USA institute of Atmospheric Physics Chinese Academy of SciencesBeijing 100029China

The Tibetan Plateau(TP)exerts a profound influence on global climate over million-year timescales due to its past ***,whether the ongoing climate changes over the TP,particularly the persistent reduction in its local albedo(referred to as“TP surface darkening”),can exert global impacts remains *** this study,a state-of-the-art coupled land–atmosphere global climate model has been employed to scrutinize the impact of TP darkening on polar climate *** indicate that the projected TP darkening has the potential to generate a stationary Rossby wave train,thereby modulating the atmospheric circulation in the high-latitudes of the Northern Hemisphere and instigating a dipole-like surface air temperature anomaly pattern around the Arctic *** additional experiment suggests that the projected Arctic warming may in return warm the TP,thus forming a bi-directional linkage between these two climate *** their association with vast ice reservoirs,the elucidation of this mechanism in our study is crucial in advancing our comprehension of Earth system climate projections.

关键词： Tibetan Plateau High-latitude Northern Hemisphere Arctic Climate change Albedo Surface darkening

Multi-Objective Optimization of the Ultrasonic Scalpel Rod and Tip with Improved Performance:Vibration Frequency,Amplitude,and Service Life

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Chinese Journal of Mechanical Engineering 2024年第4期37卷 107-119页

作者： Jiaqi Zhao Yuhao Zhai Xuzhe Jia Naiwen Deng Kunxu Li Guangchao Han Rong Chen Dong Wang Wei Bai School of Mechanical Engineering and Electronic Information China University of GeosciencesWuhan 430074China Shenzhen Research institute China University of GeosciencesShenzhen 518057China College of Engineering Mathematics and Physical SciencesUniversity of ExeterExeter EX44QFUK Shenzhen Huazhong University of Science and Technology Research institute Shenzhen 518000China

Ultrasonic scalpel design for minimally invasive surgical procedures is mainly focused on optimizing cutting ***,an important issue is the low fatigue life of traditional ultrasonic scalpels,which affects their long-term reliability and effectiveness and creates hidden dangers for *** this study,a multi-objective optimal design for the cutting performance and fatigue life of ultrasonic scalpels was proposed using finite element analysis and fatigue *** optimal design parameters of resonance frequency and amplitude were *** setting the transition fillet and keeping the gain structure away from the node position to enable the scalpel to have a high service life with excellent cutting *** frequency modulation method of setting the vibration node bosses at the node position and setting the vibration antinode grooves at the antinode position was ***,the mechanism of the influence of various design elements,such as tip,shank,node position,and antinode position,on the resonance frequency,amplitude,and fatigue life of the ultrasonic scalpel was analyzed,and the optimal design principles of the ultrasonic scalpel were *** proposed ultrasonic scalpel design was confirmed by simulations,impedance measurements,and liver tissue cutting experiments,demonstrating its feasibility and enhanced *** research introduces innovative design strategies to improve the fatigue life and performance of ultrasonic scalpels to address an important issue in minimally invasive surgery.

关键词： Multi-objective optimal design Minimally invasive surgical procedures Service life Ultrasonic scalpel

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青藏高原地表变暗与北极气候变化间的共振（英文）

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Science Bulletin 2024年第3期 367-374页

作者：汤舒畅朴世龙 David M.Holland 阚飞汪涛姚檀栋李熙晨 Sino-French institute for Earth System Science College of Urban and Environmental Sciences Peking University State Key Laboratory of Tibetan Plateau Earth System Resources and Environment Institute of Tibetan Plateau Research Chinese Academy of Sciences courant institute of mathematical sciences New York University institute of Atmospheric Physics Chinese Academy of Sciences

The Tibetan Plateau(TP) exerts a profound influence on global climate over million-year timescales due to its past uplift. However, whether the ongoing climate changes over the TP, particularly the persistent reduction in its local albedo(referred to as ‘‘TP surface darkening”), can exert global impacts remains elusive. In this study, a state-of-the-art coupled land–atmosphere global climate model has been employed to scrutinize the impact of TP darkening on polar climate changes. Results indicate that the projected TP darkening has the potential to generate a stationary Rossby wave train, thereby modulating the atmospheric circulation in the high-latitudes of the Northern Hemisphere and instigating a dipole-like surface air temperature anomaly pattern around the Arctic region. An additional experiment suggests that the projected Arctic warming may in return warm the TP, thus forming a bi-directional linkage between these two climate systems. Given their association with vast ice reservoirs, the elucidation of this mechanism in our study is crucial in advancing our comprehension of Earth system climate projections.

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Data-driven systematic analysis of waterborne viruses and health risks during the wastewater reclamation process

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Environmental Science and Ecotechnology 2024年第3期19卷 80-90页

作者： Jia-Xin Ma Xu Wang Yi-Rong Pan Zhao-Yue Wang Xuesong Guo Junxin Liu Nan-Qi Ren David Butler Research Center for Eco-Environmental sciences Chinese Academy of SciencesBeijing100085China State Key Laboratory of UrbanWater Resource and Environment School of Civil and Environmental EngineeringHarbin Institute of TechnologyShenzhenShenzhen518055China University of Chinese Academy of sciences Beijing100049China Centre for Water Systems College of EngineeringMathematics and Physical SciencesUniversity of ExeterExeterEX44QFUnited Kingdom

Waterborne viral epidemics are a major threat to public *** interest in wastewater reclamation highlights the importance of understanding the health risks associated with potential microbial hazards,particularly for reused water in direct contact with *** study focused on identifying viral epidemic patterns in municipal wastewater reused for recreational applications based on long-term,spatially explicit global literature data during 2000e2021,and modelled human health risks from multiple exposure pathways using a well-established quantitative microbial risk assessment *** median viral loads in municipal wastewater ranged from 7.92×10^(4)to 1.4×10^(6)GC L^(-1)in the following ascending order:human adenovirus(HAdV),norovirus(NoV)GII,enterovirus(EV),NoV GI,rotavirus(RV),and severe acute respiratory syndrome coronavirus 2(SARSCoV-2).Following secondary or tertiary wastewater treatment,NoV GI,NoV GII,EV,and RV showed a relatively higher and more stable log reduction value with medians all above 0.8(84%),whereas SARSCoV-2 and HAdV showed a relatively lower reduction,with medians ranging from 0.33(53%)to 0.55(72%).A subsequent disinfection process effectively enhanced viral removal to over 0.89-log(87%).The predicted event probability of virus-related gastrointestinal illness and acute febrile respiratory illnesses in reclaimed recreational water exceeded the World Health Organization recommended recreational risk benchmark(5%and 1.9%,respectively).Overall,our results provided insights on health risks associated with reusing wastewater for recreational purposes and highlighted the need for establishing a regulatory framework ensuring the safety management of reclaimed waters.

关键词： Reclaimed water Waterborne virus Recreational Human health Data-driven analysis

The exchange Attack and the Mixture Differential Attack Revisited: From the Perspective of Automatic Evaluation

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Chinese Journal of Electronics 2024年第1期33卷 19-29页

作者： Kexin QIAO Zhiyu ZHANG Zhongfeng NIU Liehuang ZHU School of Cyberspace Science and Technology Beijing Institute of Technology State Key Laboratory of Cryptology institute of Information Engineering Chinese Academy of Sciences School of Cryptography University of Chinese Academy of Sciences

Recent results show that the differential properties within quadruples boom as a new inspiration in cryptanalysis of Advanced Encryption Standard(AES)-like constructions. These methods include the exchange attack proposed in Asiacrypt’19, the mixture differential attack proposed in To SC’18, etc., where the essential properties are obtained by manually scrutinizing the structures of the AES-like constructions. This paper presents a novel framework and an automatic tool based on mixed integer linear programming to search for mixture differential distinguishers for general constructions. This framework considers what equality patterns among quadruples can make a distinguisher and traces how the patterns propagate through cipher components with accurate probability *** this tool, a 5-round AES distinguishing attack with lower complexity and more 6-round distinguishing attacks in the chosen plaintext scenarios are deduced. We prove that no exchange-type or mixture differential distinguisher exists for 7 and above rounds AES if the details of the Sbox and Mix Columns matrix are not taken into account.

关键词： Ciphers Estimation Encryption Mixed integer linear programming Complexity theory Standards

Correcting Climate Model Sea Surface Temperature Simulations with Generative Adversarial Networks:Climatology,Interannual Variability,and extremes

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Advances in Atmospheric sciences 2024年第7期41卷 1299-1312页

作者： Ya WANG Gang HUANG Baoxiang PAN Pengfei LIN Niklas BOERS Weichen TAO Yutong CHEN BO LIU Haijie LI State Key Laboratory of Numerical Modeling for Atmospheric sciences and Geophysical Fluid Dynamics Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China Laboratory for Regional Oceanography and Numerical Modeling Qingdao National Laboratory for Marine Science and TechnologyQingdao 266237China College of Earth and Planetary sciences University of Chinese Academy of SciencesBeijing 100049China Earth System Modelling School of Engineering and DesignTechnical University of MunichOttobrunn 85521Germany Potsdam institute for Climate Impact Research Potsdam 14412Germany Department of Mathematics and Global Systems institute University of ExeterExeter EX44QEUK CMA Earth System Modeling and Prediction Centre(CEMC) Chinese Academy of Meteorological SciencesBeijing 100081China

Climate models are vital for understanding and projecting global climate change and its associated ***,these models suffer from biases that limit their accuracy in historical simulations and the trustworthiness of future *** these challenges requires addressing internal variability,hindering the direct alignment between model simulations and observations,and thwarting conventional supervised learning ***,we employ an unsupervised Cycle-consistent Generative Adversarial Network(CycleGAN),to correct daily Sea Surface Temperature(SST)simulations from the Community Earth System Model 2(CESM2).Our results reveal that the CycleGAN not only corrects climatological biases but also improves the simulation of major dynamic modes including the El Niño-Southern Oscillation(ENSO)and the Indian Ocean Dipole mode,as well as SST ***,it substantially corrects climatological SST biases,decreasing the globally averaged Root-Mean-Square Error(RMSE)by 58%.Intriguingly,the CycleGAN effectively addresses the well-known excessive westward bias in ENSO SST anomalies,a common issue in climate models that traditional methods,like quantile mapping,struggle to ***,it substantially improves the simulation of SST extremes,raising the pattern correlation coefficient(PCC)from 0.56 to 0.88 and lowering the RMSE from 0.5 to *** enhancement is attributed to better representations of interannual,intraseasonal,and synoptic scales *** study offers a novel approach to correct global SST simulations and underscores its effectiveness across different time scales and primary dynamical modes.

关键词： generative adversarial networks model bias deep learning El Niño-Southern Oscillation marine heatwaves

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How Does ESG Performance Impact Corporate Financing Costs?An Empirical Study in China

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Journal of Systems Science and Information 2024年第2期12卷 229-244页

作者： Wei LI Mei MEI Xiaoyan YU Jiahao WANG Tiangeng (Becky) GENG School of Economics and Management University of Chinese Academy of SciencesBeijing 100190China institute of Medical Information&Library Chinese Academy of Medical SciencesBeijing 100005China Business and Management Royal HollowayUniversity of LondonSurrey TW200EXUK Krieger School of Arts and sciences Johns Hopkins UniversityBaltimore MD 21218USA

In the background of the green transformation of the economy and society,the ESG performance of enterprises has been paid more and more attention in the investment ***,previous studies have inadequately explored how the ESG performance affects corporate financing *** on the information asymmetry theory,this paper analyzes the impact mechanism of ESG performance on corporate financing ***,taking 1044 A-share listed companies in2016–2020 as a sample,through the sorting and analysis of ESG report disclosure and rating data,the company’s ESG performance indicators are obtained,and an empirical model is built to test the relationship between ESG performance and corporate financing *** paper constructs a panel regression model using ESG rating data and corporate financial data and finds that in the overall sample,the higher the ESG performance,the lower the equity financing cost;The higher the ESG performance,the lower the debt financing *** addition,it also discussed the moderating effect of enterprise scale and media attention on the impact of ESG performance on enterprise financing *** empirical results show that the influence of company size on ESG performance on financing costs has a moderating effect and a positive moderating effect.

关键词： ESG performance financing cost corporate heterogeneity media attention

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Artificial intelligence is transforming the research paradigm of environmental science and engineering

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Environmental Science and Ecotechnology 2024年第3期19卷 1-3页

作者： Xu Wang Guangtao Fu Nan-Qi Ren State Key Laboratory of Urban Water Resource and Environment School of Civil and Environmental EngineeringHarbin Institute of TechnologyShenzhenShenzhen518055China Centre for Water Systems College of EngineeringMathematics and Physical SciencesUniversity of ExeterExeterEX44QFUnited Kingdom

Artificial intelligence(AI),particularly through its datacrunching powerhouse,machine learning(ML),is revolutionizing the way we approach high-throughput data to obtain underlying mechanisms,characterizing,forecasting,and making evidencebased decisions in many fundamental science ***,a pressing question has emerged in the scientific community in recent years:How can we effectively interpret AI algorithms and gauge their contributions to fundamental research?

关键词： has gauge forecasting