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Acta Mechanica Sinica 2024年第8期40卷 1-16页

作者： Bei Ding Wei Wang Juliang Xiao Zhiqiang Wu Cheng Liu School of Mechanical Engineering Tianjin UniversityTianjin300350China Tianjin Key Laboratory of nonlinear dynamics and Control Tianjin300350China Key Laboratory of Modern Mechanisms and Equipment Design of the State Ministry of Education Tianjin UniversityTianjin300350China

The shell composed of large-scale parts is the essential component of mechanical structures in the aerospace,shipping,and railway *** workpieces are characterized by thin walls and weak rigidity,thus requiring an effective technology for high-performance ***,an embedded locally resonant metamaterial with double resonators is proposed and combined with the magnetic follow-up support technology to attenuate the vibration of thin-walled parts for the first *** band structures and parametric adjustment laws are systematically investigated and validated by analytical calculation and finite element method,which proves the proposed model is broadband,lightweight,and flexible in low *** characteristics,as well as the relatively simple structure,are unique advantages for thin-walled structure ***,mirror milling experiments have been performed to assess the slave module with the proposed *** the results,the root mean square amplitude of the thin-walled workpiece with the combined device decreases by nearly 9%,which means that the performance has been improved by the combined ***,this work provides an integrated and efficient solution for vibration suppression in thin-walled parts milling,which extends locally resonant metamaterials to practical engineering fields and helps to improve the status quo of mirror milling from the perspective of metamaterials.

关键词： Local resonance Band gap Thin-walled workpieces Vibration suppression

Ultra-wide band gap and wave attenuation mechanism of a novel star-shaped chiral metamaterial

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Applied Mathematics and Mechanics(English Edition) 2024年第7期45卷 1261-1278页

作者： Shuo WANG Anshuai WANG Yansen WU Xiaofeng LI Yongtao SUN Zhaozhan ZHANG Qian DING G.D.AYALEW Yunxiang MA Qingyu LIN Department of Mechanics Tianjin UniversityTianjin300350China Tianjin Key Laboratory of nonlinear dynamics and Control Tianjin UniversityTianjin300350China State Key Laboratory of Metastable Materials Science and Technology Yanshan UniversityQinhuangdao066004Hebei ProvinceChina

A novel hollow star-shaped chiral metamaterial(SCM)is proposed by incorporating chiral structural properties into the standard hollow star-shaped metamaterial,exhibiting a wide band gap over 1500 *** broaden the band gap,solid single-phase and two-phase SCMs are designed and simulated,which produce two ultra-wide band gaps(approximately 5116 Hz and 6027 Hz,respectively).The main reason for the formation of the ultra-wide band gap is that the rotational vibration of the concave star of two novel SCMs drains the energy of an elastic *** impacts of the concave angle of a single-phase SCM and the resonator radius of a two-phase SCM on the band gaps are *** the concave angle leads to an increase in the width of the widest band gap,and the width of the widest band gap increases as the resonator radius of the two-phase SCM ***,the study on elastic wave propagation characteristics involves analyzing frequency dispersion surfaces,wave propagation directions,group velocities,and phase ***,the analysis focuses on the transmission properties of finite periodic *** solid single-phase SCM achieves a maximum vibration attenuation over 800,while the width of the band gap is smaller than that of the two-phase *** metamaterials exhibit high vibration attenuation capabilities,which can be used in wideband vibration reduction to satisfy the requirement of ultra-wide frequencies.

关键词： metamaterial ultra-wide band gap wave propagation vibration suppression

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

dynamics of Ring Dark Solitons and the Following Vortices in Spin-1 Bose–Einstein Condensates

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Chinese Physics Letters 2024年第7期41卷 18-26页

作者：钟毓 Houria Triki 周勤 Research group of nonlinear Optical Science and Technology Research Center of Nonlinear ScienceSchool of Mathematical and Physical SciencesWuhan Textile UniversityWuhan 430200China Radiation Physics Laboratory Department of PhysicsFaculty of SciencesBadji Mokhtar UniversityP.O.Box 1223000 AnnabaAlgeria State Key Laboratory of New Textile Materials and Advanced Processing Technologies Wuhan Textile UniversityWuhan 430200China

This work focuses on the evolution behaviors of ring dark solitons(RDSs) and the following vortices after the collapses of RDSs in spin-1 Bose–Einstein condensates. We find that the weighted average of the initial depths of three components determines the number and motion trajectories of vortex dipoles. For the weighted average of the initial depths below the critical depth, two vortex dipoles form and start moving along the horizontal *** the weighted average depth above the critical depth, two or four vortex dipoles form, and all start moving along the vertical axis. For the RDS with weighted average depth at exactly the critical point, four vortex dipoles form, half of the vortex dipoles initiate movement vertically, and the other half initiate movement *** conclusion is applicable to the two-component system studied in earlier research, indicating its universality.

关键词： vortex dipole Einstein

Radial solution of the Logarithmic Laplacian system

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Applied Mathematics(A Journal of Chinese Universities) 2024年第1期39卷 114-124页

作者： ZHANG Li-hong NIE Xiao-feng WANG Guo-tao Bashir Ahmad School of Mathematics and Computer Science Shanxi Normal UniversityLinfen 041004China nonlinear Analysis and Applied Mathematics(NAAM)Research group Department of MathematicsFaculty of ScienceKing Abdulaziz UniversityJeddah 21589Saudi Arabia.

The paper generalizes the direct method of moving planes to the Logarithmic Laplacian ***,some key ingredients of the method are discussed,for example,Narrow region principle and Decay at ***,the radial symmetry of th... 详细信息

关键词： the Logarithmic Laplacian system radial symmetry the direct method of moving planes

Ecological network analysis reveals complex responses of tree species life stage interactions to stand variables

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Journal of Forestry Research 2024年第1期35卷 29-43页

作者： Hengchao Zou Huayong Zhang Tousheng Huang Research Center for Engineering Ecology and nonlinear Science North China Electric Power UniversityBeijing 102206People’s Republic of China

Tree interactions are essential for the structure,dynamics,and function of forest ecosystems,but variations in the architecture of life-stage interaction networks(LSINs)across forests is ***,we constructed 16 LSINs in the mountainous forests of northwest Hebei,China based on crown overlap from four mixed forests with two dominant tree *** results show that LSINs decrease the complexity of stand densities and basal areas due to the interaction cluster *** addition,we found that mature trees and saplings play different roles,the first acting as“hub”life stages with high connectivity and the second,as“bridges”controlling information flow with high *** the forests,life stages with higher importance showed better parameter stability within *** results reveal that the structure of tree interactions among life stages is highly related to stand *** efforts contribute to the understanding of LSIN complexity and provide a basis for further research on tree interactions in complex forest communities.

关键词： Tree interactions Life stages Interaction networks Ecological complexity

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

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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 University Department of Mechanics Tianjin University Tianjin Key Laboratory of nonlinear dynamics and Control Tianjin University School of Mechanical and Automotive Engineering Guangxi University of Science and Technology

The suppression of low-frequency vibration and noise has always been an important issue in a wide range of engineering applications. To address this concern,a novel square hierarchical honeycomb metamaterial capable of reducing low-frequency noise has been developed. By combining Bloch's theorem with the finite element method,the band structure is calculated. Numerical results indicate that this metamaterial can produce multiple low-frequency bandgaps within 500 Hz, with a bandgap ratio exceeding50%. The first bandgap spans from 169.57 Hz to 216.42 Hz. To reveal the formation mechanism of the bandgap, a vibrational mode analysis is performed. Numerical 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 vibrations. Additionally, detailed parametric analyses are conducted to investigate the effect of θ, i.e., the angle between the protruding corner of the structure and the horizontal direction, on the band structures and the total effective bandgap width. It is found that reducing θ is conducive to obtaining lower frequency bandgaps. The propagation characteristics of elastic waves in the structure are explored by the group velocity, phase velocity, and wave propagation direction. Finally, the transmission characteristics of a finite periodic structure are investigated experimentally. The 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 O321 LATTICE WAVES GAP

Composite Fractional Trapezoidal Rule with Romberg Integration

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Computer Modeling in Engineering & Sciences 2024年第9期140卷 2729-2745页

作者： Iqbal M.Batiha Rania Saadeh Iqbal H.Jebril Ahmad Qazza Abeer A.Al-Nana Shaher Momani Department of Mathematics Al Zaytoonah University of JordanAmman11733Jordan nonlinear dynamics Research Center(NDRC) Ajman UniversityAjman 346United Arab Emirates Department of Mathematics Faculty of ScienceZarqa UniversityZarqa13110Jordan Department of Mathematics Prince Sattam Bin Abdulaziz UniversityAlkharj11942Saudi Arabia Department of Mathematics The University of JordanAmman11942Jordan

The aim of this research is to demonstrate a novel scheme for approximating the Riemann-Liouville fractional integral *** would be achieved by first establishing a fractional-order version of the 2-point Trapezoidal rule and then by proposing another fractional-order version of the(n+1)-composite Trapezoidal *** particular,the so-called divided-difference formula is typically employed to derive the 2-point Trapezoidal rule,which has accordingly been used to derive a more accurate fractional-order formula called the(n+1)-composite Trapezoidal ***,in order to increase the accuracy of the proposed approximations by reducing the true errors,we incorporate the so-called Romberg integration,which is an extrapolation formula of the Trapezoidal rule for integration,into our proposed *** numerical examples are provided and compared with a modern definition of the Riemann-Liouville fractional integral operator to illustrate the efficacy of our scheme.

关键词： Composite fractional Trapezoidal rule Romberg integration

Tracing Sources of Geochemical Anomalies in a Deeply Buried Volcanic-Related Hydrothermal Uranium Deposit:the Daguanchang Deposit,Northern Hebei Province,North China Craton

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Journal of Earth Science 2024年第4期35卷 1186-1195页

作者： Yangyang Zhang Yuelong Chen Dapeng Li Huan Kang Mingliang Fang Yunliang Xu School of Earth Science and Resources China University of GeosciencesBeijing100083China State Key Laboratory of Earthquake dynamics Institute of GeologyChina Earthquake AdministrationBeijing100083China Jinchuan group Company Limited Jinchang737104China China-Explo Tian Cheng(Beijing)Technology Company Limited Beijing100093China

Radon(Rn)and helium(He)gases from uranium decay form distinct anomalies related to buried uranium *** order to trace the geochemical anomalous sources from the volcanic-related uranium deposits in deeply buried areas,systematical Rn contents and He isotope ratios were analyzed from the Daguanchang uranium *** soil gas Rn concentrations above the deep uranium are ten times higher than those in barren areas,indicating that instantaneous Rn content measurements can be used to detect deeply buried *** helium isotope ratios(^(3)He/^(4)He)of the unmineralized samples from the mineralized drill hole(ZK1)are relatively lower and uniform compared to those of the samples from no-mineral drill hole(ZK2).However,the Th and U contents of the drill core samples from ZK1 are slightly lower than those of the samples from ZK2,indicating that the lower 3He/4He ratios in ZK1 are most likely due to the addition of 4He from underlying uranium *** differences in the instantaneous Rn contents are consistent with the variations in the He isotope ratios of the drill core *** results demonstrate that soil gas Rn and ^(3)He/^(4)He ratios are useful tracers and can indicate the existence of deeply buried volcanic-related hydrothermal uranium ores.

关键词： tracers radon helium ^(3)He/^(4)He ratio uranium deposits Daguanchang deposit

A method for extracting the preseismic gravity anomalies over the Tibetan Plateau based on the maximum shear strain using GRACE data

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Earth and Planetary Physics 2024年第4期8卷 589-608页

作者： Hui Wang DongMei Song XinJian Shan Bin Wang College of Oceanography and Space Informatics China University of Petroleum(East China)Qingdao 266580China PCI Technology group Co. Ltd.Guangzhou 510660China Laboratory for Marine Mineral Resources Qingdao National Laboratory for Marine Science and TechnologyQingdao 266200China State Key Laboratory of Earthquake dynamics Beijing 100029China

The occurrence of earthquakes is closely related to the crustal geotectonic movement and the migration of mass,which consequently cause changes in *** Gravity Recovery And Climate Experiment(GRACE)satellite data can be used to detect gravity changes associated with large ***,previous GRACE satellite-based seismic gravity-change studies have focused more on coseismic gravity changes than on preseismic gravity ***,the noise of the north–south stripe in GRACE data is difficult to eliminate,thereby resulting in the loss of some gravity information related to tectonic *** explore the preseismic gravity anomalies in a more refined way,we first propose a method of characterizing gravity variation based on the maximum shear strain of gravity,inspired by the concept of crustal *** offset index method is then adopted to describe the gravity anomalies,and the spatial and temporal characteristics of gravity anomalies before earthquakes are analyzed at the scales of the fault zone and plate,*** this work,experiments are carried out on the Tibetan Plateau and its surrounding areas,and the following findings are obtained:First,from the observation scale of the fault zone,we detect the occurrence of large-area gravity anomalies near the epicenter,oftentimes about half a year before an earthquake,and these anomalies were distributed along the fault ***,from the observation scale of the plate,we find that when an earthquake occurred on the Tibetan Plateau,a large number of gravity anomalies also occurred at the boundary of the Tibetan Plateau and the Indian ***,the aforementioned experiments confirm that the proposed method can successfully capture the preseismic gravity anomalies of large earthquakes with a magnitude of less than 8,which suggests a new idea for the application of gravity satellite data to earthquake research.

关键词： Gravity Recovery And Climate Experiment(GRACE)data maximum shear strain offset index K preseismic gravity anomalies Tibetan Plateau fault zone