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Multi-layer quasi-zero-stiffness meta-structure for high-efficiency vibration isolation at low frequency

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Applied Mathematics and Mechanics(English Edition) 2024年第7期45卷 1189-1208页

作者： Jiahao zhou jiaxi zhou Hongbin PAN Kai WANG Changqi CAI Guilin WEN College of Mechanical and Vehicle Engineering Hunan UniversityChangsha410082China State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body The Ministry of Science and TechnologyChangsha410082China School of Mechanical Engineering Zhejiang Sci-Tech UniversityHangzhou310018China School of Mechanical Engineering Yanshan UniversityQinhuangdao066004Hebei ProvinceChina

An easily stackable multi-layer quasi-zero-stiffness(ML-QZS)meta-structure is proposed to achieve highly efficient vibration isolation performance at low ***,the distributed shape optimization method is used to design the unit cel,i.e.,the single-layer QZS(SL-QZS)***,the stiffness feature of the unit cell is investigated and verified through static ***,the unit cells are stacked one by one along the direction of vibration isolation,and thus the ML-QZS meta-structure is ***,the dynamic modeling of the ML-QZS vibration isolation metastructure is conducted,and the dynamic responses are obtained from the equations of motion,and verified by finite element(FE)***,a prototype of the ML-QZS vibration isolation meta-structure is fabricated by additive manufacturing,and the vibration isolation performance is evaluated *** results show that the vibration isolation performance substantially enhances when the number of unit cells *** importantly,the ML-QZS meta-structure can be easily extended in the direction of vibration isolation when the unit cells are properly ***,the ML-FQZS vibration isolation meta-structure should be a fascinating solution for highly efficient vibration isolation performance at low frequency.

关键词： quasi-zero stiffness(QZS) meta-structure high efficiency low frequency vibration isolation

Design of quasi-zero-stiffness elastic diodes for low-frequency nonreciprocity through machine learning

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Acta Mechanica Sinica 2024年第7期40卷 137-151页

作者： Junsen He jiaxi zhou Kai Wang Qiang Wang College of Mechanical and Vehicle Engineering Hunan UniversityChangsha 410082China Key Laboratory of Advanced Design and Manufacturing Technology for Vehicle Hunan UniversityChangsha 410082China Department of Mechanical Engineering Hong Kong Polytechnic UniversityHong KongChina

Elastic diodes with nonreciprocity have the potential to enable unidirectional modulation of elastic ***,it is a challenge to achieve nonreciprocity at low frequencies(<100 Hz)using existing elastic *** paper proposes a quasizero-stiffness(QZS)elastic diode to resolve such a tough issue and fulfill high-quality low-frequency *** proposed elastic diode is invented by combining a QZS locally resonant metamaterial with a linear one,where the beneficial nonlinearity of the QZS metamaterial facilitates opening an amplitude-dependent band gap at very low ***,the dispersion relation of the QZS metamaterial is derived theoretically based on the harmonic balance method(HBM).Then,the transmissibility of the QZS elastic diode in both the forward and backward directions is calculated through theoretical analyses and numerical ***,the influences of system parameters on the low-frequency nonreciprocal effect are *** results indicate that considerable nonreciprocity is observed at a quite low frequency(e.g.,9 Hz),which is achieved by amplitude-dependent local resonance combined with interface ***,a machine learning-based design optimization is introduced to evaluate and enhance the nonreciprocal effect of the QZS elastic *** the aid of machine learning(ML),the computational cost of predicting nonreciprocal effects during design optimization can be significantly *** design optimization,the nonreciprocal frequency bandwidth can be broadened while maintaining considerable isolation quality at low frequencies.

关键词： Nonreciprocity Low-frequency Elastic diode Quasi-zero-stiffness Nonlinear elastic metamaterials Machine learning

Modeling and analysis of gradient metamaterials for broad fusion bandgaps

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Applied Mathematics and Mechanics(English Edition) 2024年第7期45卷 1155-1170页

作者： Changqi CAI Chenjie ZHU Fengyi ZHANG Jiaojiao SUN Kai WANG Bo YAN jiaxi zhou School of Mechanical Engineering Zhejiang Sci-Tech UniversityHangzhou310018China School of Material and Environmental Engineering Hangzhou Dianzi UniversityHangzhou310018China College of Mechanical and Vehicle Engineering Hunan UniversityChangsha410082China

A gradient metamaterial with varying-stiffness local resonators is proposed to open the multiple bandgaps and further form a broad fusion ***,three local resonators with linearly increasing stiffness are periodically attached to the spring-mass chain to construct the gradient *** dispersion relation is then derived based on Bloch's theorem to reveal the fusion bandgap *** dynamic characteristic of the finite spring-mass chain is investigated to validate the fusion of multiple ***,the effects of the design parameters on multiple bandgaps are *** results show that the metamaterial with a non-uniform stiffness gradient pattern is capable of opening a broad fusion bandgap and effectively attenuating the longitudinal waves within a broad frequency region.

关键词： local resonance mechanism elastic metamaterial stiffness gradient bandgap fusion broadband wave attenuation

Identification and characterization of human hematopoietic mesoderm

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Science China(Life Sciences) 2024年第2期67卷 320-331页

作者： Yuqi Wen Jingjing Zhao Runqing Zhang Fan Liu Xiaoyuan Chen Dan Wu Mengge Wang Cuicui Liu Pei Su Panpan Meng Yiyue Zhang Xin Gao Lu Wang Hongtao Wang jiaxi zhou State Key Laboratory of Experimental Hematology National Clinical Research Center for Blood DiseasesHaihe Laboratory of Cell EcosystemInstitute of Hematology&Blood Diseases HospitalChinese Academy of Medical Sciences&Peking Union Medical CollegeTianjin 300020China Tianjin Institutes of Health Science Tianjin 301600China CAMS Center for Stem Cell Medicine PUMC Department of Stem Cell and Regenerative MedicineTianjin 300020China Division of Cell Developmental and Integrative BiologySchool of MedicineSouth China University of TechnologyGuangzhou 510006China

The embryonic mesoderm comprises heterogeneous cell subpopulations with distinct lineage *** is unclear whether a bias for the human hematopoietic lineage emerges at this early developmental *** this study,we integrated single-cell transcriptomic analyses of human mesoderm cells from embryonic stem cells and embryos,enabling us to identify and define the molecular features of human hematopoietic mesoderm(HM)cells biased towards hematopoietic *** discovered that BMP4 plays an essential role in HM specification and can serve as a marker for HM ***,BMP4 acts as a downstream target of HDAC1,which modulates the expression of BMP4 by deacetylating its *** of HDAC significantly enhances HM specification and promotes subsequent hematopoietic cell *** conclusion,our study identifies human HM cells and describes new mechanisms for human hematopoietic development.

关键词： hematopoietic mesoderm human pluripotent stem cells human embryos BMP4 HDAC1

2000-2020年长江中下游地区耕地生产力对气候变化的动态响应

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应用与环境生物学报 2024年第2期30卷 238-246页

作者：周佳茜蒋艳萍乡市气象局萍乡337000 中南林业科技大学生命科学与技术学院长沙410004 中南林业科技大学南方林业生态应用技术国家工程实验室长沙410004

长江中下游地区是我国重要的粮食产区,探究其耕地生产力对气候变化的动态响应,对于应对日益增长的人类需求和不断加剧的气候变化、保障粮食安全具有重要意义.以植被净初级生产力(NPP)作为耕地生产力的评价指标,从区域尺度和格网尺度上,... 详细信息

长江中下游地区是我国重要的粮食产区,探究其耕地生产力对气候变化的动态响应,对于应对日益增长的人类需求和不断加剧的气候变化、保障粮食安全具有重要意义.以植被净初级生产力(NPP)作为耕地生产力的评价指标,从区域尺度和格网尺度上,分析2000-2020年长江中下游地区耕地NPP的时空变化特征,并量化NPP与气候因子(气温和降水)的相关性.结果显示:(1)从区域尺度上看,研究期间耕地NPP以3.42 g m^(-2)a^(-1)的速率呈波动上升趋势,并且在2013年出现了突变点.长江以南地区的耕地NPP要高于长江以北地区,离长江越远的耕地NPP越高;从格网尺度上看,研究期间大部分耕地的NPP呈上升趋势,但是未来可能呈增长放缓或退化趋势;(2)研究区耕地NPP与年降水量、年均气温呈正相关关系,降水的影响要强于温度;降水量对耕地NPP的影响具有显著的南北差异,降水与NPP呈正相关的耕地大部分位于长江以北地区,呈负相关的耕地大部分位于长江以南地区.气温与耕地NPP的相关关系在沿长江的梯度带上具有显著的空间差异,离长江越近,NPP与气温呈负相关的耕地越多.本研究表明气候变化的湿暖化促进了耕地植被的生长,耕地NPP对气候变化的响应具有显著的空间异质性.(图7表1参45)

关键词：耕地生产力气候变化植被净初级生产力空间异质性长江中下游地区

赣南兴国—宁都萤石成矿带分形结构及成矿与找矿前景

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吉林大学学报（地球科学版） 2024年第1期54卷 108-124页

作者：崔中良周家喜罗开江西应用科技学院光华宝石与艺术设计学院南昌330100 云南大学地球科学学院昆明650500 云南省高校关键矿产成矿学重点实验室昆明650500

萤石是一种重要的非金属战略性关键矿产资源,其成矿规律及找矿预测广受矿床学界关注。赣南兴国—宁都萤石成矿带地处NE向武夷山成矿带与EW向南岭成矿带交汇复合部位,发育一系列萤石矿床。虽然前人对该区萤石矿床进行过较为系统的研究,... 详细信息

萤石是一种重要的非金属战略性关键矿产资源,其成矿规律及找矿预测广受矿床学界关注。赣南兴国—宁都萤石成矿带地处NE向武夷山成矿带与EW向南岭成矿带交汇复合部位,发育一系列萤石矿床。虽然前人对该区萤石矿床进行过较为系统的研究,认为其主要受断裂构造控制,但区内断裂构造和萤石矿床空间分布的定量表征及两者之间的耦合关系鲜有报道。本文基于分形理论刻画赣南兴国—宁都成矿带断裂构造和萤石矿床之间的分形结构特征,并探讨重点成矿与找矿区域。结果显示:研究区NE-NNE向断裂容量维、信息维和关联维分别为1.6090、1.6089、1.5947,说明本区成矿地质条件优越,NE-NNE向断裂与研究区萤石成矿关系密切。萤石矿床容量维、信息维、关联维分别为0.9379、0.9215、0.9262,含统计中心矿床时,萤石矿床数量分形分维值为0.7841,密度分形分维值为0.784;未含统计中心矿床时,萤石矿床数量分形分维值为1.1296,密度分形分维值为1.130。根据研究区断裂分维值与萤石矿床空间分布的耦合特征、萤石矿床数量及密度分形特征综合圈定了3级有利成矿区,其中Ⅰ级有利成矿区为成矿条件最佳、成矿潜力最大的区域。根据断裂分维值与矿床空间分布的耦合特征、矿床数量及密度分形特征,可快速有效圈定受断裂体系控矿的萤石矿集区或成矿带内的重点找矿区域。

关键词：兴国—宁都成矿带断裂构造萤石矿床分形结构应用前景

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非线性摩擦纳米发电俘能技术的若干进展

力学学报 2024年第9期56卷 2495-2510页

作者：谭栋国池实民欧旭周加喜王凯湖南科技大学土木工程学院湖南湘潭411201 湖南大学机械与运载工程学院长沙410082

摩擦纳米发电技术是一种基于电负性不同的材料,通过静电感应和摩擦起电的耦合作用实现材料间电荷转移,从而将环境能量转化为电能的能量俘获技术.因在物联网及其相关智慧产业以及新能源等领域的巨大应用潜力,摩擦纳米发电俘能技术自被提... 详细信息

摩擦纳米发电技术是一种基于电负性不同的材料,通过静电感应和摩擦起电的耦合作用实现材料间电荷转移,从而将环境能量转化为电能的能量俘获技术.因在物联网及其相关智慧产业以及新能源等领域的巨大应用潜力,摩擦纳米发电俘能技术自被提出后便受到极大地关注并成为国内外的研究热点.将非线性力学机制拓展至摩擦纳米发电俘能技术构造的非线性摩擦纳米发电机在低频环境激励下具有复杂的非线性动力学行为,可以产生大幅值动力学响应,进而高效地将低频环境能量转化为电能.文章首先简要介绍了摩擦纳米发电俘能原理与非线性摩擦纳米发电机的基本工作原理,然后从双稳态摩擦纳米发电俘能、多稳态摩擦纳米发电俘能和准零刚度摩擦纳米发电俘能等3个方面详细总结了非线性摩擦纳米发电俘能方法的研究工作.此外,从碰撞式摩擦纳米发电俘能、混合机制摩擦纳米发电俘能等两个方面详细阐述了非线性摩擦纳米发电俘能系统的性能提升策略.最后,通过总结非线性摩擦纳米发电俘能技术的研究进展,分析了目前研究中的不足,并对未来非线性摩擦纳米发电俘能技术的研究方向进行了展望.

关键词：能量俘获非线性系统摩擦纳米发电低频区域环境能量

Geology and C-O isotope geochemistry of carbonate-hosted Pb-Zn deposits, NW Guizhou Province, SW China

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Chinese Journal Of Geochemistry 2013年第1期32卷 7-18页

作者： DOU Song zhou jiaxi Yunnan Nonferrous Metals Geological Bureau School of Geoscience and Info-Physics Central South University State Key Laboratory of Ore Deposit Geochemistry Institute of Geochemistry Chinese Academy of Sciences

The Pb-Zn metallogenic district in NW Guizhou Province is an important part of the Yun-nan-Sichuan-Guizhou Pb-Zn metallogenic province, and also is one of the most important Pb-Zn producers in China. The hosting rocks of the Pb-Zn deposits are Devonian to Permian carbonate rocks, and the basement rocks are meta-sedimentary and igneous rocks of the Proterozoic Kunyang and Huili groups. The ore minerals are composed of sphalerite, galena and pyrite, and the gangue minerals are include calcite and dolomite. Geology and C-O isotope of these deposits were studied in this paper. The results show that δ13C and δ18O values of hydrothermal calcite, altered wall rocks-dolostone, sedimentary calcite and hosting carbonate rocks range from -5.3‰ to -0.6 ‰ (mean -3.4‰) and +11.3‰ to +20.9 ‰ (mean +17.2‰), -3.0‰ to +0.9 ‰ (mean -1.3‰) and +17.0‰ to +20.8‰ (mean +19.7‰), +0.6‰ to +2.5 ‰ (mean +1.4‰) and +23.4‰ to +26.5 ‰ (mean +24.6‰), and -1.8‰ to +3.9‰ (mean +0.7‰) and +21.0‰ to +26.8‰ (mean +22.9‰), respectively, implying that CO2 in the ore-forming fluids was mainly a result of dissolution of Devonian and Carboniferous carbonate rocks. However, it is difficult to evaluate the contribution of sediment de-hydroxylation. Based on the integrated analysis of geology, C and O isotopes, it is believed that the ore-forming fluids of these carbonate-hosted Pb-Zn deposits in this area were derived from multiple sources, including hosting carbonate rocks, Devonian to Permian sedimentary rocks and basement rocks (the Kun-yang and Huili groups). Therefore, the fluids mixing is the main precipitation mechanism of the Pb-Zn deposit in this province.

关键词：铅锌矿床碳酸盐岩碳氧同位素综合地质中国西南同位素地球化学贵州省托管

2002—2022年萍乡市气候变化对水稻生长及产量的影响

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南方农业 2024年第6期18卷 83-85页

作者：周佳茜张碧旋萍乡市气象局江西萍乡337000 莲花县气象局江西莲花337100

为探析气候变化对水稻生长情况及产量的影响,选取2002—2022年江西省萍乡市水稻生长期的气候数据进行统计整理,深入分析各气候变化对水稻生长及产量的影响。结果表明,高温对水稻的生长和发育有一定的影响,早稻生殖生长阶段的最高气温与... 详细信息

为探析气候变化对水稻生长情况及产量的影响,选取2002—2022年江西省萍乡市水稻生长期的气候数据进行统计整理,深入分析各气候变化对水稻生长及产量的影响。结果表明,高温对水稻的生长和发育有一定的影响,早稻生殖生长阶段的最高气温与气候产量呈显著负相关。

关键词：气候变化水稻江西省萍乡市

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