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Research on the Structural Rigidity Characteristics of a Reconfigurable TBM Thrust Mechanism

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Chinese Journal of Mechanical Engineering 2019年第6期32卷 35-47页

作者： Younan xu Xinjun Liu jiyu xu School of Mechantronics and vehicle Engineering East China Jiaotong UniversityNanchang 330013China Department of Mechanical Engineering Tsinghua UniversityBeijing 100084China Department of Mechanical Engineering and Aerospace Polytechnic of TorinTorin 10135Italy

To improve the adaptability of TBMs in diverse geological environments,this paper proposes a reconfigurable Type-V thrust mechanism(V-TM)with rearrangeable working states,in which structural stiffness can be automatically altered during operation.Therefore,millions of configurations can be obtained,and thousands of instances of working status per configuration can be set respectively.Nonetheless,the complexity of configurations and diversity of working states contributes to further complications for the structural stiffness algorithm.This results in challenges such as difficulty calculating the payload compliance index and the environment adaptability index.To solve this problem,we use the configuration matrix to describe the relationship between propelling jacks under reconfiguration and adopt pattern vectors to describe the working state of each hydraulic cylinder.Then,both the dynamic compatible equation between propeller forces of the hydraulic cylinders and driving forces,and the kinematic harmonizing equation between the hydraulic cylinder displacements and their deformations are established.Next,we derive the stiffness analytical equation using Hooke’s law and the Jacobian Matrix.The proposed approach provides an effective algorithm to support structural rigidity analysis,and lays a solid theoretical foundation for calculating the performance indexes of the V-TM.We then analyze the rigidity characteristics of typical configurations under different working states,and obtain the main factors affecting structural stiffness of the V-TM.The results show the deviation degree of structural parameters in hydraulic cylinders within the same group,and the working status of propelling jacks.Finally,our constructive conclusions contribute valuable information for matching and optimization by drawing on the factors that affect the structural rigidity of the V-TM.

关键词： Reconfigurable TBM thrust mechanism,Structural rigidity characteristics Configuration matrix Patternvector Kinematic harmonizing equation Dynamic compatible equation Structural stiffness equations

Simultaneous switching of supramolecular chirality and organizational chirality driven by Coulomb expansion

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Nano Research 2022年第6期15卷 5316-5321页

作者： Ming-Xia Shi jiyu xu Kai Sun Min-Long Tao Ji-Yong Yang Da-Xiao Yang Zi-Long Wang Zuo Li Jun-Zhong Wang Qi-Kun xue Sheng Meng School of Physical Science and Technology Southwest UniversityChongqing 400715China Institute of Physics Chinese Academy of SciencesBeijing 100190China Department of Physics Tsinghua UniversityBeijing 100084China

Chiral switching is a fascinating topic and plays an important role in construction of homochirality.Nevertheless,due to the complexity and flexibility of noncovalent interactions,switching the chirality of entire supramolecular assemblies has hitherto remained a challenge.Here we report the electric field-controlled chirality switching of pentacene pinwheel arrays and two-dimensional(2D)network domains.Pentacene molecules on Cd(0001)surface form the porous network structure with building blocks of hexamer pinwheels.Driven by the electric field from a scanning tunneling microscopy(STM)tip,the supramolecular chirality of pentacene pinwheels and the organizational chirality of entire network domains can be simultaneously switched from one enantiomorph to another.Furthermore,such chiral switching is reversible and repeatable under successive voltage pulses.First-principles calculations demonstrate that electric field significantly modulates the interfacial charge transfer and induces the Coulomb expansion of pentacene layers,and the subsequent reaggregation leads to the chiral flipping of the supramolecular pinwheels and 2D domains.Our results provide a new strategy for dynamic control of the 2D chiral structures and help to steer the supramolecular assembly toward homochirality.

关键词： network switched expansion

Water transport through subnanopores in the ultimate size limit: Mechanism from molecular dynamics

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Nano Research 2019年第3期12卷 587-592页

作者： jiyu xu Chongqin Zhu Yifei Wang Hui Li Yongfeng Huang Yutian Shen Joseph S. Francisco Xiao Cheng Zeng Sheng Meng Institute of Physics Chinese Academy of Sciences Beijing 100190 China School of Physical Sciences University of Chinese Academy of Sciences Beijing 100049 China Department of Chemistry University of Nebraska Lincoln NE 68588 USA Beijing Advanced Innovation Center for Soft Matter Science and Engineering Beijing University of Chemical Technology Beijing 100029 China

Ab initio and classical molecular dynamics simulations show that water can flow through graphdiyne—an experimentally fabricated graphene-like membrane with highly dense (2.4 × 10^18 pores/m^2), uniformly ordered, subnanometer pores (incircle diameter 0.57 nm and van der Waals area 0.06 nm^2). Water transports through subnanopores via a chemical-reaction-like activated process. The activated water flow can be precisely controlled through fine adjustment of working temperature and pressure. In contrast to a linear dependence on pressure for conventional membranes, here pressure directly modulates the activation energy, leading to a nonlinear water flow as a function of pressure. Consequently, high flux (1.6 L/Day/cm^2/MPa) with 100% salt rejection efficiency is achieved at reasonable temperatures and pressures, suggesting graphdiyne can serve as an excellent membrane for water desalination. We further show that to get through subnanopores water molecule must break redundant hydrogen bonds to form a two-hydrogen-bond transient structure. Our study unveils the principles and atomistic mechanism for water transport through pores in ultimate size limit, and offers new insights on water permeation through nanochannels, design of molecule sieving and nanofluidic manipulation.

关键词： graphdiyne subnanopore molecular dynamics water transport desalination

藏药三果汤调节Nrf2/HO-1信号通路干预高脂血症大鼠的作用机制

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中国现代应用药学 2024年第6期41卷 743-749页

作者：蒋艳赵琳琳马静彭岩枫徐继玉张得钧青海大学高原医学研究中心西宁810001 高原医学教育部重点实验室西宁810001 青海省高原医学应用基础重点实验室(青海-犹他高原医学联合重点实验室) 西宁810001 青海大学生态环境工程学院西宁810016

目的基于Nrf2/HO-1信号通路探讨藏药三果汤对高脂血症大鼠保护作用及相关作用机制。方法雄性SD大鼠48只,随机分为6组,即正常对照组、模型对照组、辛伐他汀组(3.5 mg·kg^(-1)),藏药三果汤低、中、高剂量组(0.43,0.86,1.72 g·kg^(-1)),... 详细信息

目的基于Nrf2/HO-1信号通路探讨藏药三果汤对高脂血症大鼠保护作用及相关作用机制。方法雄性SD大鼠48只,随机分为6组,即正常对照组、模型对照组、辛伐他汀组(3.5 mg·kg^(-1)),藏药三果汤低、中、高剂量组(0.43,0.86,1.72 g·kg^(-1)),每组8只。正常对照组给予基础饲料喂养,其余各组给予H10060高脂饲料喂养,制备高脂血症大鼠模型,造模的同时,各给药组每天1次给予相应药物灌胃,正常对照组、模型对照组给予等体积的生理盐水(1次·d^(-1)),连续灌胃6周。实验期间每周固定时间称取各组大鼠体质量1次,6周后试剂盒检测血清中血脂[总胆固醇(totalcholesterol,TC)、甘油三酯(triglyceride,TG)、低密度脂蛋白(low density lipoprotein,LDL)、高密度脂蛋白(high density lipoprotein,HDL)]及氧化指标[丙二醛(malondialdehyde,MDA)、超氧化物歧化酶(superoxide dismutase,SOD)、谷胱甘肽(glutathione,GSH)]的水平。Western blotting测定肝组织中核因子E2相关因子2(nuclear factor erythroid 2-related factor 2,Nrf2)、血红素氧合酶1(heme oxygenase 1,HO-1)、Keap1、醌氧化还原酶1(quinone oxidoreductase,NQO1)蛋白表达,采用Person相关性分析血脂与氧化指标之间的相关性。结果与正常对照组比较,模型对照组的体质量明显增加,血清中的TC、TG、LDL、MDA含量明显升高,而血清中HDL含量明显减低,SOD、GSH活力明显减低;与模型对照组比较,各给药组的体质量减轻,血清中的TC、TG、LDL、MDA含量明显减低,血清中的HDL含量明显升高,SOD、GSH活力明显升高。与正常对照组比较,模型对照组Keap1蛋白水平表达明显上调,Nrf2、HO-1与NQO1蛋白水平表达明显下调;与模型对照组比较,三果汤低、高剂量肝组织中的Keap1蛋白水平表达明显下调,Nrf2、HO-1与NQO1蛋白水平表达明显上调。相关性分析可见TG与SOD、HO-1及NQO1呈负相关,与Keap1呈正相关,TC与SOD、HO-1、GSH及Nrf2呈负相关,与Keap1及MDA呈正相关。结论藏药三果汤可改善高脂血症大鼠体质量及血脂水平,其机制可能与调节Nrf2/HO-1信号通路,改善氧化应激有关。

关键词：藏药三果汤高脂血症大鼠氧化应激 Nrf2/HO-1

Water on surfaces from first-principles molecular dynamics

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Chinese Physics B 2020年第11期29卷 37-43页

作者：游佩桅徐纪玉张萃孟胜 Beijing National Laboratory for Condensed Matter Physics and Institute of Physics Chinese Academy of SciencesBeijing 100190China Songshan Lake Materials Laboratory Dongguan 523808China School of Physical Sciences University of Chinese Academy of SciencesBeijing 100049China Collaborative Innovation Center of Quantum Matter Beijing 100190China

Water is ubiquitous and so is its presence in the proximity of surfaces.To determine and control the properties of interfacial water molecules at nanoscale is essential for its successful applications in environmental and energy-related fields.It is very challenging to explore the atomic structure and electronic properties of water under various conditions,especially at the surfaces.Here we review recent progress and open challenges in describing physicochemical properties of water on surfaces for solar water splitting,water corrosion,and desalination using first-principles approaches,and highlight the key role of these methods in understanding the complex electronic and dynamic interplay between water and surfaces.We aim at showing the importance of unraveling fundamental mechanisms and providing physical insights into the behavior of water on surfaces,in order to pave the way to water-related material design.

关键词： first-principles molecular dynamics water at surfaces reaction mechanism

基于分布式电源主动控制的配电网合环电压波动抑制方法

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电力自动化设备 2024年第1期44卷 49-56页

作者：欧阳金鑫陈纪宇袁毅峰许守东重庆大学输配电装备及系统安全与新技术国家重点实验室重庆400044 广东电网有限责任公司东莞供电局广东东莞523009 云南电网有限责任公司电力科学研究院云南昆明650217

配电网合环操作可能导致节点电压波动甚至越限,不仅影响负荷的正常运行,还威胁分布式电源(DG)的安全。为此,提出了一种通过DG主动控制,以抑制配电网合环电压波动的新思想。通过分析合环过程中电压波动的产生机理和影响因素,量化了抑制... 详细信息

配电网合环操作可能导致节点电压波动甚至越限,不仅影响负荷的正常运行,还威胁分布式电源(DG)的安全。为此,提出了一种通过DG主动控制,以抑制配电网合环电压波动的新思想。通过分析合环过程中电压波动的产生机理和影响因素,量化了抑制合环过程电压波动的控制需求,进而构建了抑制合环电压波动的DG可行功率集;通过刻画DG的功率可控范围,提出了基于可行功率集与功率可控范围交集判别的DG最优控制点计算方法,并提出了基于DG主动控制的配电网合环电压波动抑制方法。算例表明,该方法能够最大限度上抑制配电网故障恢复过程的合环电压波动,有效提升故障恢复过程的安全性和可靠性。

关键词：主动配电网分布式电源故障恢复电压波动功率控制

中国大陆高密度城市公园建设水平演变特征分析——从1996年到2019年

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上海城市规划 2022年第6期6卷 82-88页

作者：徐吉羽刘志强余慧洪亘伟苏州科技大学建筑与城市规划学院

高密度城市的人口与绿地矛盾日益突出,准确研判其公园建设水平的时空演变规律对新型城镇化建设有重要意义。以人口密度和经济密度综合表征城市密度,在我国2019年266个地级及以上城市基础上,遴选出当年的26个高密度城市,并以此为研究单... 详细信息

高密度城市的人口与绿地矛盾日益突出,准确研判其公园建设水平的时空演变规律对新型城镇化建设有重要意义。以人口密度和经济密度综合表征城市密度,在我国2019年266个地级及以上城市基础上,遴选出当年的26个高密度城市,并以此为研究单元探究1996—2019年高密度城市公园建设水平的演变特征。从时序来看,公园建设态势为“快速提升—增速减缓—稳步推进”,建设模式以公园个数的增加引领公园规模、公园密度的高速发展。从城市类型来看,经济密度是影响高密度进程速度和公园建设基础的重要因素,而人口密度的影响逐渐加强;“人口、经济密度极高”型、“高密度进程较快”型公园建设“主增个数,辅增规模”;“人口、经济密度双高”型、“高密度进程平稳”型公园配置最为协调。提出“重密度、重配置”“重系统、重需求”“重低碳、重效能”等发展对策,以期为“公园城市”背景下高密度城市的绿色、可持续发展提供有益探索。

关键词：高密度城市公园建设水平演变人口密度经济密度中国

基于模型识别的有源配电网单相接地故障定位方法

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电力系统保护与控制 2024年第5期52卷 51-60页

作者：许守东欧阳金鑫陈宇捷陈纪宇王建熊小伏输配电装备及系统安全与新技术国家重点实验室(重庆大学) 重庆400044

分布式电源(distributed generation,DG)大量接入使配电网继电保护面临严峻挑战。单相接地故障发生概率大,但故障信息十分微弱,特别是在DG多样化故障输出特性的影响下,有源配电网单相故障定位的准确性常难以保证。为此,提出了一种基于... 详细信息

分布式电源(distributed generation,DG)大量接入使配电网继电保护面临严峻挑战。单相接地故障发生概率大,但故障信息十分微弱,特别是在DG多样化故障输出特性的影响下,有源配电网单相故障定位的准确性常难以保证。为此,提出了一种基于模型识别的有源配电网单相接地故障定位方法。分析了配电网单相接地故障下DG的输出特性,建立了在不同故障位置下有源配电网的正序增广网络,构建了故障位置关于馈线出口以及DG输出电流的函数,建立了配电网单相接地故障位置模型,利用不同故障位置下短路电流矢量占比系数的差异性构建了新的故障定位判据。通过将单相接地故障定位问题转化为故障位置模型系数的求解问题,提高了故障定位的准确性和实用性。理论和仿真分析表明,在不同故障位置、不同过渡电阻下均能准确定位单相接地故障,具有原理清晰、故障特征量采集便捷、灵敏性和可靠性高的优点。

关键词：配电网分布式电源单相接地故障故障区段定位故障测距

纳米尺度下表界面水行为的多尺度分子动力学模拟

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中国科学：物理学、力学、天文学 2016年第5期46卷 46-58页

作者：李晖徐纪玉孟胜中国科学院物理研究所北京凝聚态物理国家实验室北京100190

表面界面处水的结构和性质是物理、生物、材料、化学、地质和纳米科学等领域里重要的研究课题.在当今对表界面水的科学研究当中,基于经典力场和第一性原理计算的分子动力学(MD)模拟起到了至关重要的作用.笔者与合作者多年来从事表界面... 详细信息

表面界面处水的结构和性质是物理、生物、材料、化学、地质和纳米科学等领域里重要的研究课题.在当今对表界面水的科学研究当中,基于经典力场和第一性原理计算的分子动力学(MD)模拟起到了至关重要的作用.笔者与合作者多年来从事表界面水的多尺度MD模拟研究,取得了一系列进展.本评述文章介绍了我们近5年来在该领域所做的一系列贡献.主要包括以下几个方面:(1)纳米水滴的接触角与衬底晶格结构的关系;(2)界面诱导的二维冰结构;(3)纳米孔道里的一维冰与铁电性;(4)纳米孔的水输运;(5)水合离子动力学与离子选择通道的微观机制.

关键词：水浸润表面第一性原理分子动力学模拟