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Journal of Materials Science & Technology 2024年第6期173卷 218-224页

作者： L.Y.Hao e.g.fu State Key Laboratory of Nuclear Physics and Technology Department of Technical PhysicsSchool of PhysicsPeking UniversityBeijing 100871China

Superconducting materials with high critical temperature have the potential to revolutionize many fields,including military,electronic communications,and power ***,scientists around the world have been tirelessly working with the ultimate goal of achieving high-temperature *** 2023,a preprint by Lee et *** South Korea claimed the discovery of ultra-high-temperature superconductivity with a critical temperature of up to 423 K in Cu-doped lead-apatite(LK-99)(arXiv:2307.12008,arXiv:2307.12037),which caused a worldwide sensation and ***,the electronic structures,phonon dynamics,and electrical conductivities of LK-99 and its parent compound lead-apatite have been calculated using first-principles *** results show that the lead-apatite compound and the LK-99 compound are insulator and half-metal *** flat band characteristic is consistent with previous *** electrical conductivity of the LK-99 compound shows two extreme points,and the electrical conductivity along the C-axis increases significantly after 400 *** phonon dispersion spectra of the compounds were investigated,demonstrating their dynamic instability.

关键词： Superconductivity LK-99 Lead-apatite First-principles calculation

Approximate Synchronization of Multi-Agent Systems over Finite Fields

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Journal of Systems Science & Complexity 2024年第4期37卷 1561-1580页

作者： YU Miao FeNg Jun-e XIA Jianwei fu Shihua SHeN Hao School of Mathematical Sciences Liaocheng UniversityLiaocheng 252059China School of Mathematics Shandong UniversityJinan 250100China School of electrical and Information engineering Anhui University of TechnologyMaanshan 243002China

In this paper,the approximate synchronization of leader-follower multiagent systems(MASs) over finite fields is studied in regard to local and global ***,the approximately synchronous state set(ASSS) is ***,combined with ASSS and transient periods,some criteria for the local and global approximate synchronization of systems are ***,the algorithms for calculating the maximum approximately synchronous basin(MASB) and the maximum control invariant set(MCIS) are ***,the global approximate synchronization of the system is achieved by designing the state feedback control,and a design algorithm of the controller using the truth matrix method is ***,the results of approximate synchronization are degenerated to complete ***,two examples are shown to demonstrate the results of this paper.

关键词： Approximate synchronization finite field multiagent system semi-tensor product state feedback control

Small Cycles Property of Some Cremer Rational Maps and Polynomials

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Chinese Annals of Mathematics,Series B 2024年第1期45卷 123-136页

作者： Rong fu Ji ZHOU Faculty of Science Yibin UniversityYibin 644000SichuanChina Department of Mathematical Sciences Sichuan Normal UniversityChengdu 610066China

This paper concerns the linearization problem on rational maps of degree d≥2 and polynomials of degree d>2 from the perspective of *** authors introduce a set l_(∞) of irrational numbers and show that if α∈l_(∞),then any rational map is not linearizable and has infinitely many cycles in every neighborhood of the fixed point with multiplier λ=e^(2πiα),Adding more constraints to cubic polynomials,they discuss the above problems by polynomial-like *** the family of polynomials,with the help of Yoccoz's method,they obtain its maximum dimension of the set in which the polynomials are non-linearizable.

关键词： Irrationally indifferent fixed point Linearization problem Small cycles property

A stochastic gradient-based two-step sparse identification algorithm for multivariate ARX systems

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Control Theory and Technology 2024年第2期22卷 213-221页

作者： Yanxin fu Wenxiao Zhao Key Laboratory of Systems and Control Academy of Mathematics and Systems ScienceChinese Academy of SciencesBeijing100190China School of Mathematical Sciences University of Chinese Academy of SciencesBeijing100049China

We consider the sparse identification of multivariate ARX systems, i.e., to recover the zero elements of the unknown parameter matrix. We propose a two-step algorithm, where in the first step the stochastic gradient (Sg) algorithm is applied to obtain initial estimates of the unknown parameter matrix and in the second step an optimization criterion is introduced for the sparse identification of multivariate ARX systems. Under mild conditions, we prove that by minimizing the criterion function, the zero elements of the unknown parameter matrix can be recovered with a finite number of observations. The performance of the algorithm is testified through a simulation example.

关键词： ARX system Stochastic gradient algorithm Sparse identification Support recovery Parameter estimation Strong consistency

Prospects and challenges in electrochemical nitrogen activation for ammonia synthesis

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Science China Chemistry 2024年第11期67卷 3510-3514页

作者： Xianbiao fu Ib Chorkendorff Department of Physics Technical University of Denmark

“The fixation of atmospheric nitrogen stands as one of the profound discoveries awaiting the ingenuity of chemists,”proclaimed William Crookes in his 1898 speech [1]. This statement swiftly surged like a colossal wa... 详细信息

关键词： ReDUCTION eFFICIeNCY N-2

Paleoclimatic application of spectral parameters to the eolian red clay of the Jianzha Basin,northeastern margin of the Tibetan Plateau

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Science China earth Sciences 2024年第6期67卷 1952-1966页

作者： Chaofe.g.fu Ju’e TIAN Xinwen XU Yougui SONg Jun ZUO Feng WANg Lin CHeN Pengfei LI Xiaoke QIANg The School of earth Science and Resources Chang’an UniversityXi’an 710054China State Key Laboratory of Loess and Quaternary geology Institute of Earth and EnvironmentCASXi’an 710061China College of Urban and environmental Science Northwest UniversityXi’an 710069China CAS Center for excellence in Quaternary Science and global Change Xi’an 710061China

Reflectance spectroscopy is rapid,inexpensive,and non-destructive and can provide important information about the mineralogy of rocks and *** measured the reflectance spectroscopy of Miocene red clay deposits on the northeastern margin of the Tibetan Plateau,with the aim of developing a rapid methodology for detecting paleoclimatic *** obtained visible/near-infrared(VNIR)and short-wave infrared(SWIR)spectroscopy data from the red clay in the Jianzha Basin,and analyzed their relationship with independent paleoclimatic records,including mineral contents and environmental magnetic *** results show that the VNIR parameters,including D500,D900,R500,and R900(where D and R represent the depth and reflectance of the absorption peaks around 500 and 900 nm,respectively)are temperature-sensitive and correlated with the magnetic susceptibility,frequency-dependent magnetic susceptibility,and the marine δ^(18)O *** results of frequency-domain analysis of the VNIR parameters show that they reflect climate change on orbital *** parameters,such as AS1400,D1400/D1900 and D1900(where AS represents the asymmetry of the absorption peaks around1400 nm),are correlated with the illite and montmorillonite content,and they are sensitive to the weathering *** spectral parameters of the eolian red clay in the Jianzha Basin reflect regional climatic changes caused by the uplift of the Tibetan Plateau at~8.5 Ma and global climatic cooling at~7.2 Ma,and thus they are applicable as both regional and global paleoenvironmental indicators.

关键词： Visible/near-infrared spectroscopy Short-wave infrared spectroscopy Paleoclimatic indicators Red clay Tibetan Plateau

Relationship between seismic structures and the diverse rupture processes of the 2023 Türkiye earthquake doublet

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Science China earth Sciences 2024年第9期67卷 2810-2823页

作者： Zhi WANg Yi fu Shunping PeI CAS Key Laboratory of Ocean and Marginal Sea geology South China Sea Institute of OceanologyChinese Academy of SciencesGuangzhou 510301China Southern Marine Science and engineering guangdong Laboratory(guangzhou) Guangzhou 511458China Key Laboratory of Tibetan Plateau earth System Environment and Resources(TPESER)Institute of Tibetan Plateau ResearchChinese Academy of SciencesBeijing 100101China University of Chinese Academy of Sciences Beijing 100049China

Recent geodetic and seismological observations of two major earthquakes in southeastern Türkiye in February 2023 have revealed complex rupture initiation,propagation,and segmentation along the east Anatolian Fault Zone(eAFZ)and surrounding ***,the role of upper crust structures along the eAFZ in determining the diverse rupture processes of this earthquake doublet remains *** further investigate this,we employed double-difference location and seismic tomography techniques to determine high-resolution seismic velocities(V_(P),V_(S))and Poisson’s ratio(σ)structures using a multiparameter joint tomographic *** dataset includes 100,833 high-quality source-receiver travel-time pairs of P-and *** find that the unique rupture processes of this earthquake doublet were primarily influenced by contrasting crustal seismic structures and localized geological *** M_(w)7.8 mainshock was initiated within a transitional edge zone characterized by a rigid part(asperity)of the seismogenic zone with sharp contrast variations in rock strength ranging from low to high along the *** comparison,the M_(w)7.6 rupture originated in a ductile belt featuring fluid saturation with low-VP,low-VS,and high-σvalues that extended parallel to the Cardak *** pronounced contrast structures observed along the former rupture can be attributed to the oblique collision system between the weakened section of the east Anatolian plateau and the brittle Arabian platform,while the latter rupture was initiated within the ductile structure associated with fluid intrusion caused by the northward subduction of the Cyprus slab and subsequent ***,the occurrence of the first earthquake(e1)serves to alleviate shear stress on the second earthquake(e2)fault,potentially impeding the initiation of an e2 *** the contrary,this event also significantly reduces the normal stress acting on the e2 fault due to a double left-lateral strike-slip system

关键词： 2023 Turkiye earthquake doublet Joint seismic tomography Tomographic transition edge Seismic rupture process Strong fault coupling

Nonlinear uncertainty impact of geometric variations on aerodynamic performance of low-pressure turbine blades with ultra-high loading under extreme operational conditions

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Chinese Journal of Aeronautics 2024年第5期37卷 281-300页

作者： Xiaojing WANg Zhengping ZOU Chao fu Pengcheng DU School of energy and Power engineering Beihang UniversityBeijing 100191China National Key Laboratory of Science and Technology on Aero-engine Aero-Thermodynamics Beihang UniversityBeijing 100191China Research Institute of Aero-engine Beihang UniversityBeijing 100191China

Uncertainty impact of random geometric variations on the aerodynamic performance of low-pressure turbine blades is considerable,which is further amplified by the current ultra-high-lift design trend for weight ***,this uncertainty impact on ultra-highly loaded blades under extreme operational conditions near the margins with potential large-scale open separation is focused on in this *** is demonstrated that this impact is significant,unfavourable,and nonlinear,which is clearly severer under extreme *** addition to the overall attenuation and notable scattering of specific performance,the operational margins with open separation are also notably scattered with great risk of significant *** scattering and nonlinearity are dominated by the variations in leading-edge *** thinning of leading edge triggers local transition,enhancing downstream friction and reducing resistance to open separation,which is further exacerbated by operational ***,the opposite thickening yields less benefit,implying *** unfavourable impact highlights the need for robust aerodynamic design,where both a safer operational condition and a more robust blade are indispensable,i.e.,a compromise among performance,weight,and *** the necessary limitation of loading levels,a mid-loaded design is recommended to reduce adverse pressure gradients in both the leading edge and rear region of the suction side,which helps to decrease the susceptibility of the transition and open separation to random *** improvements can also be achieved by appropriately thickening the leading edge.

关键词： Ultra-highly loaded turbine blade geometric variations Uncertainty analysis Operational margins Robust aerodynamic design Nonlinearity

Safety,immunogenicity and protective effect of sequential vaccination with inactivated and recombinant protein COVID-19 vaccine in the elderly:a prospective longitudinal study

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Signal Transduction and Targeted Therapy 2024年第6期9卷 2738-2747页

作者： Hong-Hong Liu Yunbo Xie Bao-Peng Yang Huan-Yue Wen Peng-Hui Yang Jin-e Lu Yan Liu Xi Chen Meng-Meng Qu Yang Zhang Wei-guo Hong Yong-gang Li Junliang fu fu-Sheng Wang Out-patient Department of Day Diagnosis and Treatment The Fifth Medical Center of Chinese PLA General HospitalBeijing 100039China Senior Department of Infectious Diseases The Fifth Medical Center of Chinese PLA General HospitalNational Clinical Research Center for Infectious DiseasesBeijing 100039China Chinese PLA Medical School Chinese PLA General HospitalBeijing 100039China Hunyuan County People’s Hospital Datong 037499 Shanxi ProvinceChina Faculty of Hepato-Pancreato-Biliary Surgery Institute of Hepatobiliary SurgeryThe First Medical CenterChinese PLA General HospitalBeijing 100853China

The safety and efficacy of COVID-19 vaccines in the elderly,a high-risk group for severe COVID-19 infection,have not been fully *** clarify these issues,this prospective study followed up 157 elderly and 73 young participants for 16 months and compared the safety,immunogenicity,and efficacy of two doses of the inactivated vaccine BBIBP-CorV followed by a booster dose of the recombinant protein vaccine *** results showed that this vaccination protocol was safe and tolerable in the *** administering two doses of the BBIBP-CorV,the positivity rates and titers of neutralizing and anti-RBD antibodies in the elderly were significantly lower than those in the young *** the ZF2001 booster dose,the antibody-positive rates in the elderly were comparable to those in the young;however,the antibody titers remained ***,age,and underlying diseases were independently associated with vaccine immunogenicity in elderly *** pseudovirus neutralization assay showed that,compared with those after receiving two doses of BBIBP-CorV priming,some participants obtained immunological protection against BA.5 and BF.7 after receiving the ZF2001 *** infection symptoms last longer in the infected elderly and pre-infection antibody titers were negatively associated with the severity of post-infection *** antibody levels in the elderly increased significantly after breakthrough infection but were still lower than those in the *** data suggest that multiple booster vaccinations at short intervals to maintain high antibody levels may be an effective strategy for protecting the elderly against COVID-19.

关键词： vaccination vaccine doses

Towards rational design in electrochemical denitrification by analyzing pH dependence

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National Science Review 2024年第6期11卷 223-232页

作者： Huan Li Dong Luan Jun Long Xiaoyan fu Jianping Xiao State Key Laboratory of Catalysis Dalian Institute of Chemical Physics Chinese Academy of Sciences University of Chinese Academy of Sciences

A small fraction of NOx（<1%） always exists in CO2feedstock（e.g. exhausted gas）, which can significantly reduce the efficiency of CO2electroreduction by ～30%. Hence, electrochemical denitrification is the precondi... 详细信息

A small fraction of NOx（exists in CO2feedstock（e.g. exhausted gas）, which can significantly reduce the efficiency of CO2electroreduction by ～30%. Hence, electrochemical denitrification is the precondition of CO2electroreduction. The pH effect is a key factor, and can be used to tune the selectivity between N2and N2O production in electrochemical denitrification. However, there has been much controversy for many years about the origin of pH dependence in electrocatalysis. To this end, we present a new scheme to accurately model the pH dependence of the electrochemical mechanism. An extremely small pH variation from pH 12.7 to pH 14 can be accurately reproduced for N2O production. More importantly,the obviously different pH dependence of N2production, compared to N2O, can be attributed to a cascade path. In other words, the N2was produced from the secondary conversion of the as-produced N2O molecule（the major product）, instead of the original reactant NO. This is further supported by more than 35 experiments over varying catalysts（Fe, Ni, Pd, Cu, Co, Pt and Ag）, partial pressures（20%, 50% and100%） and potentials（from -0.2 to 0.2 V vs. reversible hydrogen electrode）. All in all, the insights herein overturn long-lasting views in the field of NO electroreduction and suggest that rational design should steer away from catalyst engineering toward reactor optimization.

关键词： electrocatalysis denitrification pH-dependence nitric oxide reduction reaction mechanism