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Low-frequency bandgap and vibration suppression mechanism of a novel square hierarchical honeycomb metamaterial

Applied mathematics and Mechanics(English Edition) 2024年第10期45卷 1841-1856页

作者： Xingjian DONG Shuo WANG Anshuai WANG Liang WANG Zhaozhan ZHANG Yuanhao TIE Qingyu LIN Yongtao SUN State Key laboratory of Mechanical Systems and Vibration Shanghai Jiao Tong UniversityShanghai 200240China Department of Mechanics Tianjin UniversityTianjin 300350China Tianjin Key laboratory of nonlinear Dynamics and Control Tianjin UniversityTianjin 300350China School of Mechanical and Automotive Engineering Guangxi University of Science and TechnologyLiuzhou 545006Guangxi Zhuang Autonomous RegionChina

The suppression of low-frequency vibration and noise has always been an important issue in a wide range of engineering *** address this concern,a novel square hierarchical honeycomb metamaterial capable of reducing low-frequency noise has been *** combining Bloch’s theorem with the finite element method,the band structure is *** results indicate that this metamaterial can produce multiple low-frequency bandgaps within 500 Hz,with a bandgap ratio exceeding 50%.The first bandgap spans from 169.57 Hz to 216.42 *** reveal the formation mechanism of the bandgap,a vibrational mode analysis is *** analysis demonstrates that the bandgap is attributed to the suppression of elastic wave propagation by the vibrations of the structure’s two protruding corners and overall expansion ***,detailed parametric analyses are conducted to investigate the effect ofθ,i.e.,the angle between the protruding corner of the structure and the horizontal direction,on the band structures and the total effective bandgap *** is found that reducingθis conducive to obtaining lower frequency *** propagation characteristics of elastic waves in the structure are explored by the group velocity,phase velocity,and wave propagation ***,the transmission characteristics of a finite periodic structure are investigated *** results indicate significant acceleration amplitude attenuation within the bandgap range,confirming the structure’s excellent low-frequency vibration suppression capability.

关键词： wave propagation vibration suppression metamaterial low-frequency bandgap

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INVARIANTS-PRESERVING DU FORT-FRANKEL SCHEMES AND THEIR ANALYSES FOR nonlinear SCHRÖDINGER EQUATIONS WITH WAVE OPERATOR

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Journal of Computational mathematics 2024年第3期42卷 814-850页

作者： Dingwen Deng Zhijun Li College of mathematics and Information science Nanchang Hangkong UniversityNanchang 330063China

Du Fort-Frankel finite difference method(FDM)was firstly proposed for linear diffusion equations with periodic boundary conditions by Du Fort and Frankel in *** is an explicit and unconditionally von Neumann stable ***,there has been no research work on numerical solutions of nonlinear Schrödinger equations with wave operator by using Du Fort-Frankel-type finite difference methods(FDMs).In this study,a class of invariants-preserving Du Fort-Frankel-type FDMs are firstly proposed for one-dimensional(1D)and two-dimensional(2D)nonlinear Schrödinger equations with wave *** using the discrete energy method,it is shown that their solutions possess the discrete energy and mass conservative laws,and conditionally converge to exact solutions with an order of for ofο(T^(2)+h_(x)^(2)+(T/h_(x))^(2))1D problem and an order ofο(T^(2)+h_(x)^(2)+h_(Y)^(2)+(T/h_(X))^(2)+(T/h_(y))^(2))for 2D problem in ***,τdenotes time-step size,while,hx and hy represent spatial meshsizes in x-and y-directions,***,by introducing a stabilized term,a type of stabilized invariants-preserving Du Fort-Frankel-type FDMs are *** not only preserve the discrete energies and masses,but also own much better stability than original ***,numerical results demonstrate the theoretical analyses.

关键词： nonlinear Schrodinger equations with wave operator Du Fort-Frankel finite difference methods Discrete energy and mass conservative laws Numerical convergence

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Divergence-Free Virtual Element Method for the Stokes Equations with Damping on Polygonal Meshes

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Numerical mathematics(Theory,Methods and Applications) 2024年第1期17卷 210-242页

作者： Yu Xiong Yanping Chen Jianwei Zhou Qin Liang School of mathematics and Computational science Hunan Key Laboratory for Computation and Simulation in Science and EngineeringXiangtan UniversityXiangtan 411105P.R.China School of mathematics and Statistics Linyi University Linyi 276005P.R.China School of Mathematical sciences South China Normal UniversityGuangzhou 510631P.R.China

In this paper,we construct,analyze,and numerically validate a family of divergence-free virtual elements for Stokes equations with nonlinear damping on polygonal *** virtual element method is H1-conforming and exact *** virtue of these properties and the topological degree argument,we rigorously prove the well-posedness of the proposed discrete *** con-vergence analysis is carried out,which imply that the error estimate for the velocity in energy norm does not explicitly depend on the *** experiments on various polygonal meshes validate the accuracy of the theoretical analysis and the asymptotic pressure robustness of the proposed scheme.

关键词： Optimal error estimates divergence-free virtual element nonlinear damping term.

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Generating barcodes for nanopore sequencing data with PRO

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Fundamental Research 2024年第4期4卷 785-794页

作者： Ting Yu Zitong Ren Xin Gao Guojun Li Renmin Han Research Center for mathematics and Interdisciplinary sciences Frontiers Science Center for Nonlinear Expectations(Ministry of Education)Shandong UniversityShandong 266000China Computer Electrical and Mathematical Sciences and Engineering Division&Computational Bioscience Research CenterKing Abdullah University of Science and TechnologyThuwal 23955Saudi Arabia

DNA barcodes,short and unique DNA sequences,play a crucial role in sample identification when processing many samples simultaneously,which helps reduce experimental ***,the low quality of long-read sequencing makes it difficult to identify barcodes accurately,which poses significant challenges for the design of barcodes for large numbers of samples in a single sequencing ***,we present a comprehensive study of the generation of barcodes and develop a tool,PRO,that can be used for selecting optimal barcode sets and *** formulate the barcode design problem as a combinatorial problem and prove that finding the optimal largest barcode set in a given DNA sequence space in which all sequences have the same length is theoretically *** practical applications,we developed the novel method PRO by introducing the probability divergence between two DNA sequences to expand the capacity of barcode kits while ensuring demultiplexing ***,the maximum size of the barcode kits designed by PRO is 2,292,which keeps the length of barcodes the same as that of the official ones used by Oxford Nanopore Technologies(ONT).We validated the performance of PRO on a simulated nanopore dataset with high error *** demultiplexing accuracy of PRO reached 98.29%for a barcode kit of size 2,922,4.31%higher than that of Guppy,the official demultiplexing *** the size of the barcode kit generated by PRO is the same as the official size provided by ONT,both tools show superior and comparable demultiplexing accuracy.

关键词： Third-generation sequencing Nanopore sequencing DNA barcode Farthest point sampling algorithm High throughput

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High-Q resonant terahertz metasurfaces

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Opto-Electronic Advances 2024年第4期7卷 1-3页

作者： Manukumara Manjappa Yuri Kivshar Department of Instrumentation and Applied Physics Indian Institute of ScienceBengaluru 560012India nonlinear Physics Center Australian National UniversityCanberra ACT 2601Australia

In photonics, the quest for high-quality (high Q) resonances driven by the physics of bound states in the continuum (BIC)1,2has motivated researchers to explore innovative avenues for realizing groundbreaking applications in lasing3, sensing4and nonlinear photonics5. A conventional strategy to harness the properties of BICs involves breaking the symmetry of resonators in a uniform lattice, allowing uncoupled modes to interact with free space that opens a leaky channel in the form of socalled (quasi) q BIC6modes.

关键词： breaking resonant symmetry

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Mathematical model and optimal control analysis of coffee berry borer with temperature and rainfall variability

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International Journal of Biomathematics 2024年第5期17卷 177-204页

作者： Abdisa Shiferaw Melese Department of Applied mathematics Adama Science and Technology UniversityAdamaEthiopia

This study focuses on a nonlinear deterministic mathematical model for coffee berry borer(Hypothenemus hampei)with temperature and rainfall *** the model analysis,CBB free and coexistence equilibria are *** basic reproduction numbers at a minimum and maximum temperature and rainfall are *** qualitative analysis of the model revealed the scenario for equilibria together with basic reproduction *** local stability of equilibria is established through the Jacobian matrix and the Routh-Hurwitz criteria,while the global stability of equilibria is demonstrated using an appropriate Lyapunov *** normalized sensitivity analysis has also been performed to observe the impact of different parameters on basic reproduction *** proposed model is extended into an optimal control problem by incorporating two control variables,namely,the preventive measure variable based on the separation of susceptible coffee berries from contacting the pests based on biological control and an increase in the death rate of colonizing females of CBB based on chemical *** disease control analysis is examined using Pontryagin's minimum ***,the numerical simulations are performed based on analytical results and are discussed ***,the cost-effectiveness of control strategies to determine the best approach to minimize the CBB burden was *** study is significant in providing reliable information on how one can use mathematical modeling to improve the roles of control strategies and prevention in CBB transmission in a coffee *** outcome of the study may guide public agriculture policymakers on optimal control strategies to control the *** particular,using chemical pesticides is very effective to combat pests with minimum costs.

关键词： Hypothenemus hampei climate variability optimal control cost-effective analysis numerical simulation

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Micropillar compression using discrete dislocation dynamics and machine learning

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Theoretical & Applied Mechanics Letters 2024年第1期14卷 39-47页

作者： Jin Tao Dean Wei Junshi Yu Qianhua Kan Guozheng Kang Xu Zhang School of Mechanics and Aerospace Engineering Southwest Jiaotong UniversityChengdu 610031China State Key laboratory of nonlinear Mechanics Institute of MechanicsChinese Academy of SciencesBeijing 100190China

Discrete dislocation dynamics(DDD)simulations reveal the evolution of dislocation structures and the interaction of *** study investigated the compression behavior of single-crystal copper micropillars using fewshot machine learning with data provided by DDD *** types of features are considered:external features comprising specimen size and loading orientation and internal features involving dislocation source length,Schmid factor,the orientation of the most easily activated dislocations and their distance from the free *** yielding stress and stress-strain curves of single-crystal copper micropillar are predicted well by incorporating both external and internal features of the sample as separate or combined *** is found that the machine learning accuracy predictions for single-crystal micropillar compression can be improved by incorporating easily activated dislocation features with external ***,the effect of easily activated dislocation on yielding is less important compared to the effects of specimen size and Schmid factor which includes information of orientation but becomes more evident in small-sized ***,incorporating internal features,especially the information of most easily activated dislocations,improves predictive capabilities across diverse sample sizes and orientations.

关键词： Discrete dislocation dynamics simulations Machine learning Size effects Orientation effects Microstructural features

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Output Feedback Stabilization of High-Order nonlinear Time-Delay Systems With Low-Order and High-Order nonlinearities

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IEEE/CAA Journal of Automatica Sinica 2024年第5期11卷 1304-1306页

作者： Meng-Meng Jiang Kemei Zhang Xue-Jun Xie School of mathematics science Liaocheng UniversityLiaocheng 252059China School of mathematics science Qufu Normal UniversityQufu 273165China Institute of Automation Qufu Normal UniversityQufu 273165China

Dear Editor,to This letter deals with the output feedback stabilization of a class of high-order nonlinear time-delay systems with more general low-order and high-order *** constructing reduced-order observer,based on homogeneous domination theory together with the adding a power integrator method,an output feedback controller is developed guarantee the equilibrium of the closed system globally uniformly asymptotically stable.

关键词： nonlinear stabilization guarantee

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A Study on the Transmission Dynamics of the Omicron Variant of COVID-19 Using nonlinear Mathematical Models

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Computer Modeling in Engineering & sciences 2024年第6期139卷 2265-2287页

作者： S.Dickson S.Padmasekaran Pushpendra Kumar Kottakkaran Sooppy Nisar Hamidreza Marasi Department of mathematics Periyar UniversitySalemTamilnadu636011India Faculty of Engineering and Natural sciences Istanbul Okan UniversityIstanbulTurkey Department of mathematics College of Science and Humanities in AlkharjPrince Sattam Bin Abdulaziz UniversityAlkharj11942Saudi Arabia Department of Applied mathematics Faculty of MathematicsStatistics and Computer ScienceUniversity of TabrizTabrizIran

This research examines the transmission dynamics of the Omicron variant of COVID-19 using SEIQIcRVW and SQIRV models,considering the delay in converting susceptible individuals into infected *** significant delays eventually resulted in the pandemic’s *** ensure the safety of the host population,this concept integrates quarantine and the COVID-19 *** investigate the stability of the proposed *** fundamental reproduction number influences stability *** to our findings,asymptomatic cases considerably impact the prevalence of Omicron infection in the *** real data of the Omicron variant from Chennai,Tamil Nadu,India,is used to validate the outputs.

关键词： Omicron local stability reproduction number steady states global stability

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An electromagnetic semi-active dynamic vibration absorber for thin-walled workpiece vibration suppression in mirror milling

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Applied mathematics and Mechanics(English Edition) 2024年第8期45卷 1315-1334页

作者： Jianghua KONG Bei DING Wei WANG Zhixia WANG Juliang XIAO Hongyun QIU School of Mechanical Engineering Tianjin UniversityTianjin 300350China Tianjin Key laboratory of nonlinear Dynamics and Control Tianjin 300350China Key laboratory of Modern Mechanisms and Equipment Design of the State Ministry of Education Tianjin UniversityTianjin 300350China

As critical components of aircraft skins and rocket fuel storage tank shells,large thin-walled workpieces are susceptible to vibration and deformation during machining due to their weak local *** address these challenges,we propose a novel tunable electromagnetic semi-active dynamic vibration absorber(ESADVA),which integrates with a magnetic suction follower to form a followed ESADVA(follow-ESADVA)for mirror *** system combines a tunable magnet oscillator with a follower,enabling real-time vibration absorption and condition feedback throughout the milling ***,the device supports self-sensing and frequency adjustment by providing feedback to a linear actuator,which alters the distance between *** resolves the traditional issue of being unable to directly monitor vibration at the machining point due to space constraints and tool *** frequency shift characteristics and vibration absorption performance are comprehensively *** and experimental results demonstrate that the prototyped follow-ESADVA achieves frequency synchronization with the milling tool,resulting in a vibration suppression rate of approximately 47.57%.Moreover,the roughness of the machined surface decreases by18.95%,significantly enhancing the surface *** results of this work pave the way for higher-quality machined surfaces and a more stable mirror milling process.

关键词： semi-active dynamic vibration absorber(SADVA) mirror milling selfsensing vibration absorption tuning thin-walled workpiece

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