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Stabilization and Blow-up in an Infinite Memory Wave Equation with Logarithmic Nonlinearity and Acoustic Boundary Conditions

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Journal of Systems Science & Complexity 2024年第4期37卷 1368-1391页

作者： PENG Qingqing zhang zhifei School of Mathematics and Statistics Huazhong University of Science and Technology Hubei Key Laboratory of Engineering Modeling and Scientific Computing Huazhong University of Science and Technology

In this paper, the authors consider the stabilization and blow up of the wave equation with infinite memory, logarithmic nonlinearity and acoustic boundary conditions. The authors discuss the existence of global solutions for the initial energy less than the depth of the potential well and investigate the energy decay estimates by introducing a Lyapunov function. Moreover, the authors establish the finite time blow up results of solutions and give the blow up time with upper bounded initial energy.

关键词： Acoustic boundary condition finite time blow-up general decay infinite memory logarithmic nonlinearity

PABP-driven secondary condensed phase within RSV inclusion bodies activates viral mRNAs for ribosomal recruitment

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Virologica Sinica 2024年第2期39卷 235-250页

作者： Qiang zhang Hanzhe Ye Cong Liu Haiwu Zhou Mingbin He Xiaodong Liang Yu Zhou Kun Wang Yali Qin zhifei Li Mingzhou Chen State Key Laboratory of Virology and Modern Virology Research Center College of Life SciencesWuhan UniversityWuhan430072China Taikang Center for Life and Medical Sciences Wuhan UniversityWuhan430072China Hubei Jiangxia Laboratory Wuhan430200China

Inclusion bodies(IBs)of respiratory syncytial virus(RSV)are formed by liquid-liquid phase separation(LLPS)and contain internal structures termed“IB-associated granules”(IBAGs),where anti-termination factor M2-1 and viral mRNAs are concentrated.However,the mechanism of IBAG formation and the physiological function of IBAGs are unclear.Here,we found that the internal structures of RSV IBs are actual M2-1-free viral messenger ribonucleoprotein(mRNP)condensates formed by secondary LLPS.Mechanistically,the RSV nucleoprotein(N)and M2-1 interact with and recruit PABP to IBs,promoting PABP to bind viral mRNAs transcribed in IBs by RNArecognition motif and drive secondary phase separation.Furthermore,PABP-eIF4G1 interaction regulates viral mRNP condensate composition,thereby recruiting specific translation initiation factors(eIF4G1,eIF4E,eIF4A,eIF4B and eIF4H)into the secondary condensed phase to activate viral mRNAs for ribosomal recruitment.Our study proposes a novel LLPS-regulated translation mechanism during viral infection and a novel antiviral strategy via targeting on secondary condensed phase.

关键词： Respiratory syncytial virus(RSV) Inclusion bodies(IBs) Biomolecular condensates Liquid-liquid phase separation(LLPS) Secondary condensed phase mRNA activation

Global well-posedness for the 3-D MHD equations with partial diffusion in the periodic domain

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Science China Mathematics 2022年第2期65卷 309-318页

作者： Wenji Chen zhifei zhang Jianfeng Zhou School of Mathematical Sciences Peking UniversityBeijing 100871China

In this paper, we prove the global well-posedness of the 3-D magnetohydrodynamics(MHD) equations with partial diffusion in the periodic domain when the initial velocity is small and the initial magnetic field is close... 详细信息

关键词： MHD equations global well-posedness Diophantine condition

On the L^(∞) stability of Prandtl expansions in the Gevrey class

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Science China Mathematics 2022年第12期65卷 2521-2562页

作者： Qi Chen Di Wu zhifei zhang School of Mathematical Sciences Peking UniversityBeijing 100871China School of Mathematics South China University of TechnologyGuangzhou 510641China

In this paper, we prove the L^(∞)∩ L^(2) stability of Prandtl expansions of the shear flow type as(U(y/ν1/2), 0)for the initial perturbation in the Gevrey class, where U(y) is a monotone and concave function and ν is the viscosity coefficient. To this end, we develop the direct resolvent estimate method for the linearized Orr-Sommerfeld operator instead of the Rayleigh-Airy iteration method. Our method could be applied to the other relevant problems of hydrodynamic stability.

关键词： Navier-Stokes equations shear flow Prandtl expansion

On the stability of shear flows of Prandtl type for the steady Navier-Stokes equations

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Science China Mathematics 2023年第4期66卷 679-722页

作者： Qi Chen Di Wu zhifei zhang School of Mathematical Sciences Peking UniversityBeijing 100871China School of Mathematics South China University of TechnologyGuangzhou 510641China

In this paper, we study the stability of shear flows of Prandtl type as(U(y/√ν), 0) for the steady Navier-Stokes equations under a natural spectral assumption on the linearized NS operator. The key ingredient is to solve the Orr-Sommerfeld equation. For this, we develop a direct energy method combined with the compactness method, which may be of independent interest.

关键词： Navier-Stokes equations shear flow Prandtl expansion

Outstanding electromechanical performance in piezoelectric ceramics via synergistic effects of defect engineering and domain miniaturization

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Journal of Materials Science & Technology 2023年第27期158卷 1-8页

作者： zhifei zhang Liang Chen Huajie Luo Yueyun zhang Yonghao Yao Guanfu Liu He Qi Jun Chen Beijing Advanced Innovation Center for Materials Genome Engineering Department of Physical ChemistryUniversity of Science and Technology BeijingBeijing 100083China Hainan University Haikou 570228China

Piezoelectric ceramics with high mechanical quality factor Q_(m) and large piezoelectric coefficient d_(33) are urgently required for advanced piezoelectric applications.However,obtaining both of these prop-erties simultaneously remains a difficult challenge due to their mutually restrictive relationship.Here 0.5Pb(Ni_(1/3)Nb_(2/3))O_(3)-0.5Pb(Zr_(0.3)Ti_(0.7))O_(3) piezoceramic with tetragonal(T)-rich MPB is designed as a matrix to construct the defect engineering by doping low-valent Mn ions.The strong coupling of defect dipole and T-rich phase can effectively hinder the rotation of P_(s),restrict domain wall motion and improve Q_(m).At the same time,the substituted Mn ions will introduce local random field,destroying the long-range or-dering of ferroelectric domain and reducing domain size.The miniaturized domain structure can increase poling efficiency and inhibit the reduction of d_(33).Guided by this strategy,Q_(m) has increased by more than 10 times and d_(33) has only decreased by about 25%.The optimized electromechanical performance with Q_(m)=822,d_(33)=502 pC/N,k_(p)=0.55 and tanδ=0.0069 can be obtained in the present study.

关键词： PNN-PZT ceramics Defect engineering Domain miniaturization High mechanical quality factor Q_(m) Large piezoelectric coefficient d_(33)

Quantitative Green's function estimates for lattice quasi-periodic Schr?dinger operators

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Science China Mathematics 2023年

作者： Hongyi Cao Yunfeng Shi zhifei zhang School of Mathematics Sichuan University School of Mathematical Sciences Peking University

In this paper, we establish quantitative Green’s function estimates for some higher-dimensional lattice quasi-periodic (QP) Schr?dinger operators. The resonances in the estimates can be described via a pair of symmetric zeros of certain functions and the estimates apply to the sub-exponential-type non-resonance conditions. As the application of quantitative Green’s function estimates, we prove both the arithmetic version of Anderson localization and the finite volume version of (1/2-)-H?lder continuity of the integrated density of states (IDS) for such QP Schr?dinger operators. This gives an affirmative answer to Bourgain’s problem in Bourgain (2000).

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车身多性能约束下的一体压铸三角梁轻量化设计

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中国机械工程 2024年第4期35卷 691-699页

作者：苏永雷张志飞重庆大学机械与运载工程学院重庆400044 上海小米智能技术有限公司上海200012 小米汽车科技有限公司北京100000

系统性地构建了一体压铸结构的优化方法,基于车身系统超单元模型实现多性能约束下的车身压铸件轻量化设计。首先,缩减复杂的车身系统,针对连续的车体结构,提出了子系统划分原则和方法,分别对各子系统进行超单元缩减,保证车身系统模型的... 详细信息

系统性地构建了一体压铸结构的优化方法,基于车身系统超单元模型实现多性能约束下的车身压铸件轻量化设计。首先,缩减复杂的车身系统,针对连续的车体结构,提出了子系统划分原则和方法,分别对各子系统进行超单元缩减,保证车身系统模型的分析精度并提高计算效率,为快速优化奠定基础;其次,同步考虑压铸结构单体性能和车身系统性能,采用折衷规划法归一化静动态子目标并构建综合目标函数,应用层次分析法得到子目标权重系数,进而开展了多模型拓扑优化,确定了加强筋位置分布;进一步地,同步考虑可设计与可制造性,对压铸结构变厚度拔模面进行参数化定义,并在优化过程中施加制造约束,基于构造的组合代理模型完成厚度参数设计。研究结果表明:在保证分析精度的前提下,缩减的车身系统模型可节省97.3%的计算资源;通过优化,在大幅提高车身一体压铸三角梁结构相关性能的同时,可实现轻量化,表明了所提方法的正确性和实用性。

关键词：压铸结构模型缩减拓扑优化代理模型轻量化

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Dawn of complex animal food webs:A new predatory anthozoan(Cnidaria)from Cambrian

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The Innovation 2022年第1期3卷 83-90页

作者： Qiang Ou Degan Shu zhifei zhang Jian Han Heyo Van Iten Meirong Cheng Jie Sun Xiaoyong Yao Rong Wang Georg Mayer Early Life Evolution Laboratory State Key Laboratory of Biogeology and Environmental GeologyChina University of GeosciencesBeijing 100083China Department of Zoology University of KasselKassel 34132Germany Shaanxi Key Laboratory of Early Life and Environment State Key Laboratory of Continental DynamicsDepartment of GeologyNorthwest UniversityXi’an 710069China Department of Geology Hanover CollegeHanoverIN 47243USA Cincinnati Museum Center Department of Invertebrate Paleontology1301 Western AvenueCincinnatiOH 45203USA School of Earth Science and Resources Chang’an UniversityXi’an 710054China

Cnidarians diverged very early in animal evolution;therefore,investigations of the morphology and trophic levels of early fossil cnidarians may provide critical insights into the evolution of metazoans and the origin of modern marine food webs.However,there has been a lack of unambiguous anthozoan cnidarians from Ediacaran assemblages,and undoubted anthozoans from the Cambrian radiation of metazoans are very rare and lacking in ecological evidence.Here,we report a new polypoid cnidarian,Nailiana elegans gen.et sp.nov.,represented by multiple solitary specimens from the early Cambrian Chengjiang biota(-520 Ma)of South China.These specimens show eight unbranched tentacles surrounding a single opening into the gastric cavity,which may have born multiple mesenteries.Thus,N.elegans displays a level of organization similar to that of extant cnidarians.Phylogenetic analyses place N.elegans in the stem lineage of Anthozoa and suggest that the ancestral anthozoan was a soft-bodied,solitary polyp showing octoradial symmetry.Moreover,one specimen of the new polyp preserves evidence of predation on an epifaunal lingulid brachiopod.This case provides the oldest direct evidence of macrophagous predation,the advent of which may have triggered the emergence of complex trophic/ecological relationships in Cambrian marine communities and spurred the explosive radiation of animal body plans.

关键词： China Cambrian solitary