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

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

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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

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放顶煤开采顶板控制参数优化研究

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自动化应用 2024年第15期65卷 126-129页

作者：孙永涛山西焦煤霍州煤电豁口煤业有限公司山西临汾041000

针对某矿的放顶煤工艺存在顶板管理及回采率较低的问题,通过分析巷道和破碎顶的顶板管理及回采率低的原因,提出了对采煤工艺的优化设计,具体优化了放煤步距及采放比,并进行实际应用。结果表明,将放煤步距设为1.13 m、采放比设为1.08,使... 详细信息

针对某矿的放顶煤工艺存在顶板管理及回采率较低的问题,通过分析巷道和破碎顶的顶板管理及回采率低的原因,提出了对采煤工艺的优化设计,具体优化了放煤步距及采放比,并进行实际应用。结果表明,将放煤步距设为1.13 m、采放比设为1.08,使用一采一放的放煤工艺后,工作面的回采率达到92.1%,保证了煤炭资源的高效开采。

关键词：放顶煤开采放煤步距回采率顶板管理

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Innovative Thin-Walled Structure with Transverse Negative Poisson’s Ratio for High-Performance Crashworthiness

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Acta Mechanica Solida Sinica 2023年第1期36卷 34-44页

作者： Bin Wang yongtao sun Tianjin Key Laboratory of Soft Soils and Engineering Environment Tianjin Chengjian UniversityTianjin 300384China Department of Mechanics and Tianjin Key Laboratory of Nonlinear Dynamics and Control Tianjin UniversityTianjin 300350China

In this paper,an innovative type of thin-walled structures,the convex-concave honeycomb columns(CCHCs)with transverse negative Poisson’s ratio(NPR),is proposed for energy absorbers by replacing the cell walls of square honeycomb lattice columns with sine-shaped or zigzag-shaped walls of equal *** simulations show that,under axial impact,contrary to the conventional square honeycomb columns of equal mass,the transverse cross section of NPR CCHC shrinks inward,making the cell walls of CCHC contact and interact sufficiently with each other and thus dissipate the impact energy much more *** suitably adjusting the transverse NPR,the CCHC can have the combined advantages of effective total energy absorption,high specific energy absorption and low maximum peak crushing *** research of this paper provides a new strategy for the design of high-performance energy absorbers widely used in the engineering fields of vehicle engineering,aerospace engineering etc.

关键词： Energy absorbers Convex-concave honeycomb columns(CCHC) Transverse negative Poisson’s ratio Axial impact High-performance crashworthiness

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Nonlinear dynamic behavior of a flexible asymmetric aero-engine rotor system in maneuvering flight

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Chinese Journal of Aeronautics 2020年第10期33卷 2633-2648页

作者： Tian GAO Shuqian CAO yongtao sun Department of Mechanics Tianjin UniversityTianjin 300354China Tianjin Key Laboratory of Nonlinear Dynamics and Control Tianjin 300354China National Demonstration Center for Experimental Mechanics Education Tianjin UniversityTianjin 300354China

Aero-engine rotor systems installed in aircraft are considered to have a base *** this paper,a flexible asymmetric rotor system is modeled considering the nonlinear supports of ball bearings and Squeeze Film Dampers(SFDs),and the dynamic characteristics of the rotor system under maneuvering flight are systematically *** of the translational accelerative motions,the angular motions and the pitching flight with combined translational and angular motions on nonlinear dynamic behavior of the rotor system are *** results show that,due to the nonlinear coupled effects among the rotor,ball bearings and SFDs,within the first bending resonance region,responses of the rotor show obvious nonlinear characteristics such as bistable phenomenon,amplitude jumping phenomenon and non-synchronous *** acceleration motion of the aircraft leads to axis offset of the rotor system and thus results in the reduction and the final disappearance of the bistable rotating speed *** pitching angular motion mainly affects rotational vibration of the rotor system,and thus further induces their transverse *** the pitching flight with combined translational and angular motions,a critical flight parameter is found to correspond to the conversion of two steady responses of the rotor system,in which one response displays small amplitude and synchronous vibration,and the other shows large amplitude and non-synchronous vibration.

关键词： Aero-engine rotor system Ball bearings Maneuvering flight Nonlinear dynamics Squeeze film dampers

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考虑各向异性变形的人耳鼓膜纤维增强细观本构模型

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Acta Mechanica Sinica 2024年第5期40卷 184-197页

作者：向书毅杜智博施汇斌严子铭孙永涛王杰柳占立 School of Aerospace Engineering Tsinghua University Beijing China Department of Mechanics and Tianjin Key Lab of Nonlinear Dynamics and Control Tianjin University Tianjin China Department of Otorhinolaryngology Head and Neck Surgery Beijing Tongren Hospital Capital Medical University Beijing China Beijing Engineering Research Center of Audiological Technology Beijing China

鼓膜是听觉系统的重要组成部分,位于外耳道末端,是一种含胶原的多层软组织膜。鼓膜的纤维沿着径向和环向方向高度取向,其独特而复杂的超微结构使得力学行为呈现各向异性非线性,这对于声音传输很重要.然而,同时包含这两个特征的鼓膜本构... 详细信息

鼓膜是听觉系统的重要组成部分,位于外耳道末端,是一种含胶原的多层软组织膜。鼓膜的纤维沿着径向和环向方向高度取向,其独特而复杂的超微结构使得力学行为呈现各向异性非线性,这对于声音传输很重要.然而,同时包含这两个特征的鼓膜本构模型尚未提出.在本研究中,我们建立了考虑鼓膜纤维分布的细观本构模型,模型能够同时捕捉各向异性和非线性弹性力学行为.鼓膜被认为是包含两族胶原纤维的连续纤维增强复合材料,并通过整合沿厚度方向异质材料性质建立整体力学性质.均匀化的力学性质被假定沿着厚度方向均匀分布,并由径向胶原纤维,环向胶原纤维和等效各向同性基质的三个非耦合弹性贡献叠加组成.通过逆方法并使用文献数据校准模型.仿真结果表明,特定的胶原纤维排列是鼓膜条带试样变形呈现显著空间非均匀性及各向异性的原因。通过与纤维变形相关的强度准则,可以捕获在实验中观察到的鼓膜条带各向异性局部化失效模式。胶原纤维束的旋转和非线性性质是单轴加载下鼓膜条带非线性力学行为的起源.该细观本构模型为鼓膜的各向异性和非线性弹性力学行为提供了不同的视角.这项研究提高了我们对鼓膜力学行为的理解,并有助于仿生移植物的发展.

关键词：非线性弹性力学胶原纤维细观本构模型移植物空间非均匀性非线性性质听觉系统非线性力学行为

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Moving Toward a Functional Cure for HIV-1

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Infectious Diseases & Immunity 2021年第3期1卷 161-168页

作者： Wen Kang yongtao sun Department of Infectious Diseases Tangdu HospitalThe Fourth Military Medical UniversityXi’an 710038China

Despite the recent success of suppressing human immunodeficiency virus 1(HIV-1)replication in the peripheral blood with antiretroviral therapy,elimination of the provirus from infected cells remains challenging because the virus can integrate into the host genome and become a latent proviral *** removal of these latent viral reservoirs from tissue containing infected resting memory CD4+T cells remains a major barrier to developing a cure for *** novel strategies have recently been developed for curing HIV *** include stem cell transplantation with CCR5-D32 mutated cells,initial antiretroviral treatment in the very early stage of HIV infection,gene editing to excise the HIV genome or generate CCR5-mutated HIV-1-resistant cells,“shock-and-kill”to reactivate latent HIV using latency reversal agents combined with enhanced immune clearance methods,and an emerging“block-and-lock”strategy to reactivate latent HIV using latency reversal agents combined with enhanced immune clearance ***,the high risks and limitations to scale-up in clinics,as well as poor performance in clinical trials,have hampered these *** review aims to describe the present efforts that are being made to combat HIV latency,and critically discuss the limitations and future of the cure for HIV-1.

关键词： HIV Block-and-lock Deep latency HIV latency Shock-and-kill Transcriptional reactivation

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Dynamic web service composition based on OWL-S

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Science in China(Series F) 2006年第6期49卷 843-863页

作者： Jing DONG yongtao sun Sheng YANG Kang ZHANG Department of Computer Science University of Texas at Dallas Richardson TX 75083 USA American Airlines 4333 Amon Carter Blvd Fort Worth TX 76155 USA

Composing existing web services for enterprise applications may enable higher level of reuse. However the composition processes are mostly static and lack of support for runtime redesign. In this paper, we describe our approach to the extension of the OWL-S ontology framework for dynamic web service composition. We raise the level of abstraction and propose an abstract service layer so that web services can be composed at the abstract service level instead of the concrete level. Each abstract service is attached with an instance pool including all instances of the abstract service to facilitate fail-over and dynamic compositions.

关键词： web service instance pool abstract service ontology dynamic composition

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3.5%NaCl环境中S32205双相不锈钢与N09925镍基合金的钝化膜特征及耐蚀性

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腐蚀与防护 2024年第6期45卷 15-20页

作者：卢道胜刘慧枫孙永涛董社霞杜宇峰林学强中海油田服务股份有限公司天津分公司天津300451 中国石油大学(华东)材料科学与工程学院青岛266580

采用莫特肖特基(Mott-Schottky)分析方法、电化学阻抗谱(EIS)和X射线光电子能谱(XPS)等,对比研究了S32205双相不锈钢和N09925镍基合金在3.5%NaCl溶液中的钝化膜特征和耐蚀性。结果表明:N09925镍基合金表面钝化膜的缺陷密度低于S32205双... 详细信息

采用莫特肖特基(Mott-Schottky)分析方法、电化学阻抗谱(EIS)和X射线光电子能谱(XPS)等,对比研究了S32205双相不锈钢和N09925镍基合金在3.5%NaCl溶液中的钝化膜特征和耐蚀性。结果表明:N09925镍基合金表面钝化膜的缺陷密度低于S32205双相不锈钢,两种材料表面的钝化膜中均存在Fe和Cr元素富集,主要成分为Cr和Fe的氧化物和氢氧化物;S32205双相不锈钢表面钝化膜中含有少量金属Ni,N09925镍基合金表面钝化膜中Ni含量较高,还含有Ni的氧化物和氢氧化物;N09925镍基合金的阻抗值更高,其膜层电阻和电荷传递电阻均高于S32205双相不锈钢,N09925镍基合金表面钝化膜的保护性高于S32205双相不锈钢。

关键词： S32205双相不锈钢 N09925镍基合金钝化膜电化学测试 X射线光电子能谱(XPS)

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Design and Wave Propagation Characterization of Starchiral Metamaterials

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Acta Mechanica Solida Sinica 2022年第2期35卷 215-227页

作者： Yajun Xin Han Wang Cong Wang Jinxin Yao Qian Ding Haoqiang Gao Shuliang Cheng yongtao sun Key Laboratory of Green Construction and Intelligent Maintenance for Civil Engineering of Hebei Province Yanshan UniversityQinhuangdao 060000China Hebei Province Low-Carbon and Clean Building Heating Technology Innovation Center Yanshan UniversityQinhuangdao 060000China Department of Mechanics and Tianjin Key Laboratory of Nonlinear Dynamics and Control Tianjin UniversityTianjin 300072China State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao UniversityShijiazhuang 050043China

Metamaterials with simple artificial topological properties made from industrially produced single-phase materials have extraordinary innovation and *** this paper,we investigated wave propagation characteristics of a hexastarchiral lattice metamaterial with periodic assemblies and used the finite element(FE)method to study the band gap ***,in order to understand the mechanism of band gaps,we discussed the mode shapes of unit cells and found that the bending of the ligament and the overall rotation have a high correlation with the generation of omnidirectional band *** relationships bet ween geometric parameters and band gap properties have also been systematically studied,which demonstrated that the band gaps of the proposed metamaterial could be reasonably predicted through the evolution of geometric ***,the transmission characteristics of finite sandwich panel structures composed of periodic unit cells were calculated to verify the correctness of the band gap simulation results,which proved that the proposed artificial metastructure has potential application value in vibration and noise reduction projects.

关键词： Hexastarchiral lattice metamaterials Band gap properties Finite element method Rotational resonance

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