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Frontiers of Mechanical Engineering 2016年第2期11卷 135-143页

作者： Fugui xie xin-Jun LIU The State Key Laboratory of Tribology & Institute of Manufacturing Engineering Department of Mechanical Engineering Tsinghua Uni- versity Beijing 100084 China Beijing Key Laboratory of Precision/ Ultra-precision Manufacturing Equipment and Control Tsinghua University Beijing 100084 China

This study introduces a high-speed parallel robot with Schonflies motion. This robot exhibits a promising prospect in realizing high-speed pick-and- place manipulation for packaging production lines. The robot has four identical limbs and a single platform. Its compact structure and single-platform concept provides this robot with good dynamic response potential. A line graph method based on Grassmann line geometry is used to investigate the mobility characteristics of the proposed robot. A generalized Blanding rule is also introduced into this procedure to realize mutual conversion between the line graphs for motions and constraints. Subsequently, the inverse kinematics is derived, and the singularity issue of the robot is investigated using both qualitative and quantitative approaches. Input and output transmission singularity indices are defined based on the reciprocal product in screw theory and the virtual coefficient by considering motion/force transmission performance. Thereafter, the singular loci of the proposed robot with specific geometric parameters are derived. The mobility analysis, inverse kinematics modeling, and singularity analysis conducted in this study are helpful in developing the robot.

关键词： parallel robot mobility inverse kinematics,singularity transmission performance

Domination Numbers of Undirected Toroidal Mesh

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Acta Mathematica Sinica,English Series 2012年第3期28卷 453-462页

作者： xin xie Jun Ming XU Department of Mathematics Huangshan University Department of Mathematics University of Science and Technology of China

The （d, m）-domination number γd,m is a new measure to characterize the reliability of resources-sharing in fault tolerant networks, in some sense, which can more accurately characterize the reliability of networks ... 详细信息

关键词： Undirected toroidal mesh reliability m-diameter domination number

THEORETICAL AND EXPERIMENTAL STUDY OF THE WAVE FORCES ACTING ON THE BASE WITHOUT GAP IN SHALLOW SEA

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Journal of Hydrodynamics 1991年第2期3卷 75-80页

作者： xie, Nan Qi, xin-yuan China Ship Scientific Research Cent Wuz China

Wave forces acting on the offshore structure are of importance for the structure design point of view. There is a so called 'Two Tension Leg Buoy Mooring System' designed to open up the oil field in South China Sea. Two bases of the system are sitting on the sea floor of 30 - 40 meters depth of water. In order to confirm the safety of this system, wave forces are investigated experimentally and numerically. Nowadays, the measured materials on this subject are scarce. In the model test of Dr. Chakrabarti, the test set-up necessitated a small uniform gap between the model and tank floor, and the correct results must be come from an adjustment. The authors have solved the problem. In the paper, two numerical methods are adopted: 3-D boundary integral equation method; eigen-function expression and matching method. The former consists of distribution of Haskind Green' function on the body surface. The latter, however, by dividing the whole fluid domain into subregions, the velocity potential for each subregions can be determined uniquely by matching the velocity potential on their common boundaries, which was expressed formally by its eigen function expansion. As an example, experimental and numerical results were given for a circular base in shallow sea. They agree quite well. Although both methods are effective, the matching method has more efficiency.

关键词： Hydrodynamics Fluid Structure Interaction Mathematical Techniques Boundary Element Method Ocean Engineering Structures Water Waves

The thinnest high-temperature superconductor

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National Science Review 2014年第3期1卷 324-325页

作者： xin-cheng xie School of Physics Peking University

Superconductivity is one of the most important topics in physics and materials *** superconducting transition temperature(T C)of a quasi-2D superconductor,a superconductor with one dimension smaller than the coherence length of Cooper pairs,is normally descending with decreasing sample thickness since thermal and quantum luctuations are expected to destroy the superconducting phase coherence even at low *** question of how thin

关键词： STO high UC The thinnest high-temperature superconductor SQUID

Preface： Centennial Physics at Peking University

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Frontiers of physics 2013年第5期8卷 473-474页

作者： xin-Cheng xie School of Physics Peking University Beijing 100871 China

The Year 2013 is probably as much remarkable for the development of modern physical science in China as it is for School of Physics at Peking University. One hundred years ago, the physics division was born in Peking University, as the very first physics higher education unit having appeared in modern national universities of China. Ill tile first one hundred years, the School has made distinguished contributions to the nation and to the world in both education and academia. As we celebrate the birthday of its first century and set our sights on the next, it is my great pleasure to invite you to this special issue of Frontier of Physics on ＂Centennial Physics at Peking University＂. In 1913, the ＂WuLi Men＂（Physics Division） was established at Peking University, and was later renamed the Department of Physics in 1919. With the reorganization of the Chinese system of higher education in 1952, the new Physics Department of Peking University was created from the merger of the physics departments of Peking University, Tsinghua University and Yenching University. This became the premier center for physics in China. The School of Physics was established in 2001, and includes not only the traditional fields of study in physics, but also related physical sciences. Throughout its history, the School has educated and hosted many prominent physicists, including figures such as Ta-You Wu, C. N. Yang, T. D. Lee, and Kun Huang. Today, the School of Physics includes Physics, Astronomy, Atmospheric ＆： Oceanic Sciences, and Nuclear Science ~： Technology. Research is devoted not only to tile frontiers of fundamental physics but also to the innovation of advanced technology. Major research fields include high energy physics, astroptwsics and cosmology, radioactive nuclear physics, high energy-density physics, key technologies for advanced light sources and particle beams, the interaction of particle beams with materials, mesoscopic semiconductor light emission and laser physics, ultr

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A condition-based maintenance policy for reconfigurable multi-device systems

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Advances in Manufacturing 2024年第2期12卷 252-269页

作者： Shu-lian xie Feng Xue Wei-Min Zhang Jia-Wei Zhu School of Mechanical Engineering Tongji UniversityShanghai201804People’s Republic of China

The exploration of component states for optimizing maintenance schedules in complex systems has garnered significant interest from ***,current literature usually overlooks the critical aspects of system flexibility and *** implementation of system reconfiguration can effectively mitigate system downtime and enhance production *** study proposes a dynamic condition-based maintenance policy considering reconfiguration for reconfigurable systems.A double-layer decision rule was constructed for the devices and *** achieve the best overall maintenance effect of the system,the remaining useful life probability distribution and recommended maintenance time of each device were used to optimize the concurrent maintenance time window of the devices and determine whether to reconfigure them.A comprehensive maintenance efficiency index was introduced that simultaneously considered the maintenance cost rate,reliability,and availability of the system to characterize the overall maintenance *** reconfiguration cost was included in the maintenance *** proposed policy was tested through numerical experiments and compared with different-level *** results show that the proposed policy can significantly reduce the downtime and maintenance costs and improve the overall system reliability and availability.

关键词： Condition-based maintenance(CBM) Reconfigurable system Remaining useful life Maintenance cost System reliability

Numerical Simulation of Coal Floor Fault Activation Influenced by Mining

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Journal of China University of Mining and Technology 2006年第4期16卷 385-388页

作者： WANG lian-guo MIAO xie-xing School of Sciences China University of Mining ＆ Technology Xuzhou Jiangsu 221008 China

By means of the numerical simulation software ANSYS, the activation regularity of coal floor faults caused by mining is simulated. The results indicate that the variation in horizontal, vertical and shear stresses, as well as the horizontal and vertical displacements in the upper and the lower fault blocks at the workface are almost identical. Influ- enced by mining of the floor rock, there are stress releasing and stress rising areas at the upper part and at the footwall of the fault. The distribution of stress is influenced by the fault so that the stress isolines are staggered by the fault face and the stress is focused on the rock seam around the two ends of the fault. But the influence in fault activation on the upper or the lower fault blocks of the workface is markedly different. When the workface is on the footwall of the fault, there is a horizontal tension stress area on the upper part of the fault; when the workface is on the upper part of the fault, it has a horizontal compressive stress area on the lower fault block. When the workface is at the lower fault block, the maximum vertical displacement is 5 times larger then when the workface is on the upper fault block, which greatly in- creases the chance of a fatal inrush of water from the coal floor.

关键词： mining fault activation: simulation

One more step to realistic CO_(2) reduction reactions——geometric structures evolutions at gas-solid interface

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Rare Metals 2024年第2期43卷 849-852页

作者： Ya-Qiang xie xin Yu Ting Wang College of the Environment and Ecology Xiamen UniversityXiamen361102China

A rational design of copper(Cu)nanocatalyst is critical to the efficient carbon dioxide(CO_(2))conversion toward C1/C2 chemical ***,the lack of actual information on the vicinal Cu interfaces hinders the intrinsic activitystructure correlation *** with atomic-scale in situ characterizations(AP-STM and synchrotron-based AP-XPS),Park and co-workers study and identify the adsorbate-driven morphological evolution of Cu nanoclusters on the Cu(997)surface,providing real-space evidence for the critical role of vicinal structures on Cu *** observed surface roughening trends caused by dissociated atomic oxygen and CO adsorbates subsequently affect the result of successive catalytic reactions to produce critical intermediates,such as carbonate and formate,during the CO_(2)reduction reaction.

关键词： reaction critical rational

Magnetically Recoverable PEI/Titanate@Fe_3O_4 Photocatalysts: Fabrication and Photocatalytic Properties

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Journal of Wuhan University of Technology(Materials Science) 2018年第6期33卷 1387-1394页

作者： SUN Dongya HE Liwen lian Jiqiong xie An LIN Bizhou Key Laboratory of Functional Materials and Applications of Fujian Province College of Materials Science and Engineering Xiamen University of Technology Fujian Key Laboratory of Photoelectric Functional Materials Huaqiao University

The magnetically separable ternary polyetherimide/titanate@Fe3O4(PTF) photocatalysts of special heterostructure between magnetite(Fe3O4) microspheres and titanates nanosheets modified by polyetherimide(PEI) were successfully fabricated via a simple facile hydrothermal deposition method. The as-prepared photocatalysts were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, Transmission electron microscopy and UV-vis diffuse reflectance spectroscopy etc. The results showed that the as-fabricated material had a structure of Fe3O4microspheres coated with titanates nanosheets modified by PEI. The special interfacial contact between 3 D microsphere and 2 D nanosheets in the nanoarchitectures was formed via electrostatic attraction. Furthermore, the resulted photocatalysts were tested by degradation reaction of methylene blue under visible light irradiation and demonstrated an enhanced performance than the pure Fe3O4microspheres, and the photocatalytic activity enhanced with the molar ratio of Fe3O4microspheres and modified titanate gradually, which was attributed to the expansion of the surface area and the different electrostatic contact between the Fe3O4microspheres and titanate nanosheets. Moreover, the obtained results revealed the high yield magnetic separation and efficient reusability of PTF-5(96.7%) over 3 times reuse.

关键词： Fe3O4 microspheres titanate recyclability polyetherimide photocatalyst

QoE oriented intelligent online learning evaluation technology in B5G scenario

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Digital Communications and Networks 2024年第1期10卷 7-15页

作者： Mingzi Chen xin Wei Peizhong xie Zhe Zhang School of Communications and Information Engineering Nanjing University of Posts and TelecommunicationsNanjing210003China Key Lab of Broadband Wireless Communication and Sensor Network Technology(Nanjing University of Posts and Telecommunications) Ministry of EducationNanjing210003China Institute of Higher Education Nanjing University of Posts and TelecommunicationsNanjing210003China

Students'demand for online learning has exploded during the post-COvID-19 pandemic ***,due to their poor learning experience,students'dropout rate and learning performance of online learning are not always *** technical advantages of Beyond Fifth Generation(B5G)can guarantee a good multimedia Quality of Experience(QoE).As a special case of multimedia services,online learning takes into account both the usability of the service and the cognitive development of the *** that affect the Quality of Online Learning Experience(OL-QoE)become more *** get over this dilemma,we propose a systematic scheme by integrating big data,Machine Learning(ML)technologies,and educational psychology ***,we first formulate a general definition of OL-QoE by data analysis and experimental *** formula considers both the subjective and objective factors(i.e.,video watching ratio and test scores)that most affect ***,we induce an extended layer to the classic Broad Learning System(BLS)to construct an Extended Broad Learning System(EBLS)for the students'OL-QoE *** the extended layer can increase the width of the BLS model and reduce the redundant nodes of BLS,the proposed EBLS can achieve a trade-off between the prediction accuracy and computation ***,we provide a series of early intervention suggestions for different types of students according to their predicted OL-QoE *** timely interventions,their OL-QoE and learning performance can be *** results verify the effectiveness oftheproposed scheme.

关键词： B5G Online learning Quality of experience