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The Boundary Element Method for Ordinary State-Based Peridynamics

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Computer Modeling in Engineering & Sciences 2024年第6期139卷 2807-2834页

作者： xue liang Linjuan Wang State Key Laboratory for Turbulence and Complex Systems Department of Mechanics and Engineering ScienceCollege of EngineeringPeking UniversityBeijing100871China CAPT-HEDPS and IFSA Collaborative Innovation Center of MoECollege of EngineeringPeking UniversityBeijing100871China School of Astronautics Beihang UniversityBeijing100191China

The peridynamics(PD),as a promising nonlocal continuum mechanics theory,shines in solving discontinuous *** to now,various numerical methods,such as the peridynamic mesh-free particlemethod(PD-MPM),peridynamic finite element method(PD-FEM),and peridynamic boundary element method(PD-BEM),have been ***-BEM,in particular,outperforms other methods by eliminating spurious boundary softening,efficiently handling infinite problems,and ensuring high computational ***,the existing PD-BEM is constructed exclusively for bond-based peridynamics(BBPD)with fixed Poisson’s ratio,limiting its applicability to crack propagation problems and scenarios involving infinite or semi-infinite *** this paper,we address these limitations by introducing the boundary element method(BEM)for ordinary state-based peridynamics(OSPD-BEM).Additionally,we present a crack propagationmodel embeddedwithin the framework ofOSPD-BEM to simulate crack *** validate the effectiveness of OSPD-BEM,we conduct four numerical examples:deformation under uniaxial loading,crack initiation in a double-notched specimen,wedge-splitting test,and threepoint bending *** results demonstrate the accuracy and efficiency of OSPD-BEM,highlighting its capability to successfully eliminate spurious boundary softening phenomena under varying Poisson’s ***,OSPDBEMsignificantly reduces computational time and exhibits greater consistencywith experimental results compared to PD-MPM.

关键词： Ordinary state-based peridynamics boundary element method crack propagation fracture toughness

Open-Shell Oligomers and Polymers: Theory, Characterization Methods, Molecular Design, and Applications

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Chinese Journal of Polymer Science 2024年第4期42卷 417-436页

作者： xue-Qing Wang Cheng song Ting Lei Key Laboratory of Polymer Chemistry and Physics(Ministry of Education) School of Materials Science and EngineeringPeking UniversityBeijing100871China

Open-shell oligomers and polymers have exhibited intriguing electronic and magnetic properties, making them highly desirable for a wide range of applications, including ambipolar organic field-effect transistors (OFETs), photodetectors, organic thermoelectrics, and spintronics. Although open-shell ground states have been observed in certain small molecules and doped organic semiconductors, the exploration of open-shell ground-state conjugated polymers is still limited, and the strategies for designing these polymers remain obscure. This review aims to briefly introduce the theory and characterization methods of open-shell conjugated polymers, along with an overview of recent progress and applications. The objective is to stimulate further advancements and investigations in this promising area by shedding light on the potential of open-shell conjugated polymers and the challenges that lie ahead.

关键词： Conjugated polymers Open-shell molecules High-spin ground state Donor-acceptor(D-A)polymers Optoelectronic and magnetic properties

All types of base conversions allowed by base editors

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Science China(Life Sciences) 2024年第2期67卷 431-433页

作者： Shun-Qing liang Wen xue RNA Therapeutics Institute UMass Chan Medical SchoolWorcester 01655USA Department of Molecular Cell and Cancer BiologyUMass Chan Medical SchoolWorcester 01655USA Department of Molecular Medicine UMass Chan Medical SchoolWorcester 01655USA Li Weibo Institute for Rare Diseases Research UMass Chan Medical SchoolWorcester 01655USA

Base editors(BEs) hold great promise as tools for introducing single-base-pair changes in both basic research and therapeutic applications(Rees and Liu,2018).Base editors are composed of a Cas9 nickase fused to a DNA-modifying enzyme,which chemically modifies nucleobases within a specific targeting window near the Cas9-binding site.

关键词： base bases allowed

Random Forest-Based Fatigue Reliability-Based Design Optimization for Aeroengine Structures

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Computer Modeling in Engineering & Sciences 2024年第7期140卷 665-684页

作者： xue-Qin Li Lu-Kai song School of Energy and Power Engineering Beihang UniversityBeijing100191China Department of Mechanical Engineering The Hong Kong Polytechnic UniversityKowloonHong Kong999077China Research Institute of Aero-Engine Beihang UniversityBeijing100191China

Fatigue reliability-based design optimization of aeroengine structures involves multiple repeated calculations of reliability degree and large-scale calls of implicit high-nonlinearity limit state function,leading to the traditional direct Monte Claro and surrogate methods prone to unacceptable computing efficiency and *** this case,by fusing the random subspace strategy and weight allocation technology into bagging ensemble theory,a random forest(RF)model is presented to enhance the computing efficiency of reliability degree;moreover,by embedding the RF model into multilevel optimization model,an efficient RF-assisted fatigue reliability-based design optimization framework is *** the low-cycle fatigue reliability-based design optimization of aeroengine turbine disc as a case,the effectiveness of the presented framework is *** reliabilitybased design optimization results exhibit that the proposed framework holds high computing accuracy and computing *** current efforts shed a light on the theory/method development of reliability-based design optimization of complex engineering structures.

关键词： Random forest reliability-based design optimization ensemble learning machine learning

Rainbow Pancyclicity in a Collection of Graphs Under the Dirac-type Condition

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Acta Mathematicae Applicatae Sinica 2024年第2期40卷 269-274页

作者： Lu-yi LI Ping LI xue-liang LI Center for Combinatorics and LPMC Nankai UniversityTianjin 300071China School of Mathematics and Statistics Shaanxi Normal UniversityXi’an 710062China

Let G={Gi:i∈[n]} be a collection of not necessarily distinct n-vertex graphs with the same vertex set V,where G can be seen as an edge-colored(multi)graph and each Gi is the set of edges with color i.A graph F on V is called rainbow if any two edges of F come from different Gis’.We say that G is rainbow pancyclic if there is a rainbow cycle Cℓof lengthℓin G for each integerℓ2[3,n].In 2020,Joos and Kim proved a rainbow version of Dirac’s theorem:Ifδ(Gi)≥2/n for each i∈[n],then there is a rainbow Hamiltonian cycle in *** this paper,under the same condition,we show that G is rainbow pancyclic except that n is even and G consists of n copies of Kn/2,n/*** result supports the famous meta-conjecture posed by Bondy.

关键词： rainbow Hamiltonian cycle rainbow pancyclic meta-conjecture

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A stable implicit nodal integration-based particle finite element method(N-PFEM)for modelling saturated soil dynamics

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第6期16卷 2172-2183页

作者： liang Wang xue Zhang Jingjing Meng Qinghua Lei Department of Earth Sciences ETH ZürichZürich8092Switzerland Department of Civil Engineering and Industrial Design University of LiverpoolLiverpoolL693BXUK Department of Civil Environmental and Natural Resources EngineeringLuleåUniversity of TechnologyLuleå97187Sweden Department of Earth Sciences Uppsala UniversityUppsala75105Sweden

In this study,we present a novel nodal integration-based particle finite element method(N-PFEM)designed for the dynamic analysis of saturated *** approach incorporates the nodal integration technique into a generalised Hellinger-Reissner(HR)variational principle,creating an implicit PFEM *** mitigate the volumetric locking issue in low-order elements,we employ a node-based strain smoothing *** discretising field variables at the centre of smoothing cells,we achieve nodal integration over cells,eliminating the need for sophisticated mapping operations after re-meshing in the *** express the discretised governing equations as a min-max optimisation problem,which is further reformulated as a standard second-order cone programming(SOCP)***,pore water pressure,and displacements are simultaneously determined using the advanced primal-dual interior point ***,our numerical model offers improved accuracy for stresses and pore water pressure compared to the displacement-based PFEM *** experiments demonstrate that the N-PFEM efficiently captures both transient and long-term hydro-mechanical behaviour of saturated soils with high accuracy,obviating the need for stabilisation or regularisation techniques commonly employed in other nodal integration-based PFEM *** work holds significant implications for the development of robust and accurate numerical tools for studying saturated soil dynamics.

关键词： Particle finite element method Nodal integration Dynamic saturated media Second-order cone programming(SOCP)

Mutations in the SARS-CoV-2 spike receptor binding domain and their delicate balance between ACE2 affinity and antibody evasion

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Protein & Cell 2024年第6期15卷 403-418页

作者： song xue Yuru Han Fan Wu Qiao Wang Key Laboratory of Medical Molecular Virology (MOE/NHC/CAMS) Shanghai Institute of Infectious Disease and BiosecurityShanghai Frontiers Science Center of Pathogenic Microorganisms and InfectionSchool of Basic Medical SciencesShanghai Medical CollegeFudan UniversityShanghai 200032China

Intensive selection pressure constrains the evolutionary trajectory of SARS-CoV-2 genomes and results in various novel variants with distinct mutation *** mutations,particularly those within the receptor binding domain(RBD)of SARS-CoV-2 spike(S)protein,lead to the functional alteration in both receptor engagement and monoclonal antibody(mAb)***,we review the data of the RBD point mutations possessed by major SARS-CoV-2 variants and discuss their individual effects on ACE2 affinity and immune *** single amino acid substitutions within RBD epitopes crucial for the antibody evasion capacity may conversely weaken ACE2 binding ***,this weakened effect could be largely compensated by specific epistatic mutations,such as N501Y,thus maintaining the overall ACE2 affinity for the spike protein of all major *** predominant direction of SARS-CoV-2 evolution lies neither in promoting ACE2 affinity nor evading mAb neutralization but in maintaining a delicate balance between these two ***,this review interprets how RBD mutations efficiently resist antibody neutralization and meanwhile how the affinity between ACE2 and spike protein is maintained,emphasizing the significance of comprehensive assessment of spike mutations.

关键词： ACE2 affinity maintained

Stereoselective synthesis of substituted 1,3-dienes from propargylic esters: electrophilic-metal or redox catalysis?

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Science China Chemistry 2024年第5期67卷 1384-1396页

作者： Mengfu Dai liangliang song liang-An Chen Jiangsu Collaborative Innovation Center of Biomedical Functional Materials Jiangsu Key Laboratory of New Power BatteriesSchool of Chemistry and Materials ScienceNanjing Normal UniversityNanjing 210023China Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources International Innovation Center for Forest Chemicals and MaterialsCollege of Chemical EngineeringNanjing Forestry UniversityNanjing 210037China

1,3-Diene architectures are not only widely present in natural products, pharmaceuticals, and functional organic materials but also serve as versatile building blocks to furnish important functionalized molecules in synthetic chemistry due to conjugated repeating C=C units. Accordingly, various strategies to access substituted 1,3-dienes in a stereoselective manner have been developed. However, chemo-, regio-and stereoselective synthesis of highly substituted 1,3-dienes still remains elusive and challenging. Readily available propargylic esters have emerged as an appealing class of synthetic intermediates for accessing functionalized 1,3-dienes, especially challenging tri-or tetrasubstituted variants, via transition-metal catalysis, including electrophilic metal and redox neutral catalysis. This review, for the first time, systematically highlights recent advances in transitionmetal catalyzed synthesis of substituted 1,3-dienes from propargylic esters, discusses the mechanisms and synthetic utilities, and gives the remaining challenges and potential opportunities in this field.

关键词： 1 3-diene propargylic ester Lewis acid redox catalysis transition metal

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Full waveform inversion based on hybrid gradient

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Petroleum Science 2024年第3期21卷 1660-1670页

作者： Chuang Xie Zhi-liang Qin Jian-Hua Wang Peng song Heng-Guang Shen Sheng-Qi Yu Ben-Jun Ma xue-Qin Liu Qingdao Innovation and Development Base Harbin Engineering UniversityQingdao266000ShandongChina Qingdao Innovation and Development Center Harbin Engineering UniversityQingdao266000ShandongChina CNOOC Research Institute Co. Ltd.Beijing100028China College of Marine Geoscience Ocean University of ChinaQingdao266100ShandongChina Weihai Sunfull Geophysical Exploration Equipment Co. Ltd.Weihai264209ShandongChina

The low-wavenumber components in the gradient of full waveform inversion(FWI)play a vital role in the stability of the ***,when FWI is implemented in some high frequencies and current models are not far away from the real velocity model,an excessive number of low-wavenumber components in the gradient will also reduce the convergence rate and inversion *** solve this problem,this paper firstly derives a formula of scattering angle weighted gradient in FWI,then proposes a hybrid *** hybrid gradient combines the conventional gradient of FWI with the scattering angle weighted gradient in each inversion frequency band based on an empirical formula derived *** weighted hybrid mode,we can retain some low-wavenumber components in the initial lowfrequency inversion to ensure the stability of the inversion,and use more high-wavenumber components in the high-frequency inversion to improve the convergence *** results of synthetic data experiment demonstrate that compared to the conventional FWI,the FWI based on the proposed hybrid gradient can effectively reduce the low-wavenumber components in the gradient under the premise of ensuring inversion *** also greatly enhances the convergence rate and inversion accuracy,especially in the deep part of the *** the field marine seismic data experiment also illustrates that the FWI based on hybrid gradient(HGFWI)has good stability and adaptability.

关键词： Full waveform inversion Hybrid gradient Scattering angle weighted Low-wavenumber component