检索结果-南通市图书馆

Microstructural investigation of Nd-rich phase in sintered Nd-Fe-B magnets through electron microscopy

在线全文

学校读者我要写书评

暂无评论

Journal of Rare Earths 2013年第8期31卷 765-771页

作者： FU Xin han Xiaolei DU Zhiwei FENG haibo LI Yanfeng National Center of Analysis and Testing for Non-ferrous Metals & Electronic Materials General Research Institute for Nonferrous Metals Beijing 100088 China Division of Functional Materials Central Iron and Steel Research Institute Beijing 100081 China

The distribution, morphologies and structures of intergranular Nd-rich phase in sintered Nd-Fe-B magnets were studied through electron microscopy. Backscattered electron （BSE） imaging revealed that Nd-rich particles with various morphologies and sizes were randomly distributed at the grain boundaries and the triple junctions of the tetragonal Nd2FelnB matrix. Through selected area electron diffraction （SAED） analysis under a systematic tilting condition, most intergranular Nd-rich phase particles, with sizes ranging from hundreds of nanometres to several micrometres, were identified as face-centred cubic （FCC） structure. Such particles possessed several approximate orientation relationships with their adjacent Nd2FelaB matrix grains, such as （002）Nd2Fe14B/ （200）FCC_Nd-rieh [120] Nd2Fe14B//[001]FCC Nd-fich, （002）Nd2Fe14B//（220）FCC_Nd-rich [110] Nd2Fe14B//[l12]FCC_Nd-rich, as well as （011）Nd2Fe14B// （13 1 ）rcc Nd-rich [111 ] Nd2Fe14B//[ 114]FCC Nd_rich, which could be attributed to minimising interracial energy. The combination of high- resolution electron microscopy with energy-dispersive X-ray spectroscopy revealed the internal inhomogeneous nature of Nd-rich phases. The large lattice distortion and nanoscale-ordered structures within a single Nd2rich grain were observed.

关键词： Nd-rich phases Nd-Fe-B magnets electron microscopy rare earths

Wind Power Fluctuation Compensation by Variable Speed Pumped Storage Plants in Grid Integrated System:Frequency Spectrum Analysis

在线全文

学校读者我要写书评

暂无评论

CSEE Journal of Power and Energy Systems 2021年第2期7卷 381-395页

作者： Minxiao han Girmaw Teshager Bitew Sifrash Amogne Mekonnen Wenli Yan School of Mathematics and Physics North China Electric Power UniversityBeijing 102206China College of Electrical and Computer Engineering Debre Markos UniversityEthiopia Debre Markos University College of Social ScienceEthiopia269.

Electrical power generation from wind technology is the most rapidly growing technology due to its ample ***,because of its stochastic feature,it has the unnecessary impact on the operations and stability of the power grid *** fluctuation of the grid frequency problem,for example,is more *** fluctuation of the frequency in turn impacts even the collapse of the power *** minimize such problems,a droop-vector control strategy applied on a doubly-fed induction machine based(DFIM)variable speed pumped storage(VSPS)system is proposed in this *** method is should be used as a wind power fluctuation compensation solution in the wind farm-grid integration *** system model is made on the basis of the technique called a phasor *** frequency spectrum analysis approach is used in the VSPS plant for determining the dynamic performances of the grid in case of contingencies including wind power fluctuation *** software platform MATLAB/Simulink is used for verifying the performance of the proposed *** results show that the method of the frequency spectrum analysis technique is effective for determining the wind power fluctuation and stability requirements in large power *** control strategy proposed in this paper implementing the VSC-DFIM based VSPS plant integrated with the power gird and wind farm network achieves a well-controlled power flow and stable grid frequency with the deviations being in acceptable ranges.

关键词： AC voltage droop-vector control frequency droop-vector control frequency spectrum analysis modeling and simulation power compensation VSPS VSC-DFIM wind power fluctuation

A Real-time Look-ahead Trajectory Planning Methodology for Multi Small Line Segments Path

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Mechanical Engineering 2023年第3期36卷 76-88页

作者： Sai Zhang Xinjun Liu Bingkai Yan Jie Bi Xiangdong han Department of Mechanical Engineering Tsinghua UniversityBeijing 100084China Robotphoenix Automation Technology Co. Ltd.Jinan 250100China

When a robot is required to machine a complex curved workpiece with high precision and speed,the tool path is typically dispersed into a series of points and transmitted to the *** conventional trajectory planning method requires frequent starts and stops at each dispersed point to complete the *** method not only reduces precision but also causes damage to the motors and robot.A real-time look-ahead algorithm is proposed in this paper to improve precision and minimize *** proposed algorithm includes a path-smoothing algorithm,a trajectory planning method,and a bidirectional scanning *** path-smoothing method inserts a quintic Bezier curve between small adjacent line segments to achieve G^(2)continuity at the *** trajectory planning method utilizes a quartic polynomial and a double-quartic polynomial that can achieve a constant velocity at the velocity *** bidirectional scanning module calculates the velocity at each trajectory planning segment point,simplifying calculation complexity and can be run in real *** feasibility of the proposed algorithm is verified through simulations and experiments,which can be run in real *** addition,high machining precision can be achieved by adjusting the relevant parameters.

关键词： Look-ahead Bidirectional scanning Transition scheme Bezier curve G^(2)continuity

Kinsenoside attenuates osteoarthritis by repolarizing macrophages through inactivating NF-κB/MAPK signaling and protecting chondrocytes

在线全文

学校读者我要写书评

暂无评论

Acta Pharmaceutica Sinica B 2019年第5期9卷 973-985页

作者： Feng Zhou Jingtian Mei Xiuguo han hanjun Li Shengbing Yang Minqi Wang Linyang Chu han Qiao Tingting Tang Shanghai Key Laboratory of Orthopaedic Implants Department of Orthopaedic Surgery Shanghai Ninth People’s Hospital Shanghai Jiao Tong University School of Medicine

The objective was to investigate the effect of kinsenoside(Kin) treatments on macrophage polarity and evaluate the resulting protection of chondrocytes to attenuate osteoarthritis(OA) ***264.7 macrophages were polarized to M1/M2 subtypes then administered with different concentrations of Kin. The polarization transitions were evaluated with quantitative real-time polymerase chain reaction(q RT-PCR), confocal observation and flow cytometry analysis. The mechanism of Kin repolarizing M1 macrophages was evaluated by Western blot. Further, macrophage conditioned medium(CM) and IL-1β were administered to chondrocytes. Micro-CT scanning and histological observations were conducted in vivo on anterior cruciate ligament transection(ACLT) mice with or without Kin treatment. We found that Kin repolarized M1 macrophages to the M2 phenotype. Mechanistically, Kin inhibited the phosphorylation of IκBα, which further reduced the downstream phosphorylation of P65 in nuclear factor-κB(NF-κB) signaling. Moreover, Kin inhibited mitogen-activated protein kinases(MAPK) signaling molecules p-JNK, p-ERK and p-P38. Additionally, Kin attenuated macrophage CM and IL-1β-induced chondrocyte damage. In vivo, Kin reduced the infiltration of M1 macrophages,promoted M2 macrophages in the synovium, inhibited subchondral bone destruction and reduced articular cartilage damage induced by ACLT. All the results indicated that Kin is an effective therapeutic candidate for OA treatment.

关键词： Kinsenoside Osteoarthritis Macrophages Polarization Chondrocytes

Physical Background of the Unified Scaling Law in Spiral Galaxies

在线全文

学校读者我要写书评

暂无评论

Chinese Physics Letters 2000年第12期17卷 935-936页

作者： ZOU Zhen-Long han Jin-Lin Beijing Astronomical Observatory and Beijing Astrophysical Center National Astronomical ObservatoriesChinese Academy of SciencesBeijing 100012

We discussed the physical background of the unified scaling law in spiral galaxies,and qualitatively obtained the power index of the empirical relation among the luminosity L,radius R and the rotation velocity *** also discussed the possible causes for the data dispersion on the plane in three-dimensional space of these parameters.

关键词： parameters galaxies rotation

Adaptive sampling for corrugated plate digitization using a laser displacement sensor

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2024年第5期67卷 1510-1523页

作者： WU ChengXing QI Qi CHEN BaiJin YANG JiXiang DING han State Key Laboratory of Intelligent Manufacturing Equipment and Technology School of Mechanical Science and EngineeringHuazhong University of Science and TechnologyWuhan430074China State Key Laboratory of Intelligent Manufacturing Equipment and Technology School of Materials Science and EngineeringHuazhong University of Science and TechnologyWuhan430074China

The surface quality of a corrugated plate directly determines the heat transfer property of the thermal power mechanical *** detection methods are impractical for real-world production,being slow and *** contrast,the point laser displacement sensor,employing the optical triangle method,emerges as a promising device for assessing parts with variable curvature and highly reflective *** its benefits,high-density sampling by an innate frequency introduces challenges such as data redundancy and a poor signal-to-noise ratio,potentially affecting the efficiency and precision of subsequent data *** address these challenges,adjustable frequency data sampling has been developed for this sensor,allowing adaptive sampling for corrugated plate *** process begins with surface digitization to extract discrete points,which are transformed into intersection curves using the B-spline fitting ***,dominant points are identified,considering multigeometric constraints for curvature and arch ***,the sampling signal is adjusted based on the distribution information of dominant *** results indicate that the proposed method effectively minimizes redundant sampling without compromising the accurate capture of essential geometric features.

关键词： corrugated plate laser displacement sensor adaptive sampling dominant point curvature arch height

Acute myocardial necrosis caused by aconitine poisoning:A case report

在线全文

学校读者我要写书评

暂无评论

World Journal of Clinical Cases 2022年第33期10卷 12416-12421页

作者： Yu-Ping Liao Li-han Shen Li-Hua Cai Jie Chen han-Quan Shao Department of Critical Care Medicine Dongguan People’s HospitalDongguan 523058Guangdong ProvinceChina

BACKGROUND Herbal medicine has a long history of use in the prevention and treatment of disease and is becoming increasingly popular ***,there are also widespread concerns about its *** them,the cardiotoxicity of aconitine has been *** SUMMARY We report a case of a 61-year-old male with aconitine poisoning presenting with malignant arrhythmia and severe cardiogenic shock,which was successfully managed with aggressive advanced life support and heart *** This is the first case wherein in vivo cardiac pathology was obtained,confirming that aconitine caused acute myocardial necrosis.

关键词： Aconitine ECMO Myocardial necrosis Ventricular arrhythmia Herbal medicine Case report

Micromechanical mode-localized electric current sensor

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Microsystems & Nanoengineering 2022年第2期8卷 49-58页

作者： han Li Zhao Zhang Luhan Zu Yongcun Hao Honglong Chang Ministry of Education Key Laboratory of Micro and Nano Systems for Aerospace School of Mechanical EngineeringNorthwestern Polytechnical University127 Youyi West RoadBeilin DistrictXi'an 710072China

This paper outlines the design of a novel mode-localized electric current sensor based on a mechanically sensitive element of weakly coupled resonator *** the advantage of a high voltage sensitivity of weakly coupled resonator systems,the current under test is converted to voltage via a silicon shunt resistor,which causes stiffness perturbation to one *** mode-localization phenomenon alters the energy distribution in the weakly coupled resonator system.A theoretical model of current sensing is established,and the performance of the current sensor is determined:the sensitivity of the electric current sensor is 567/A,the noise floor is 69.3 nAA/Hz,the resolution is 183.6 nA,and the bias instability is 81.6 *** mode-localized electric current sensor provides a new approach for measuring sub-microampere currents for applications in nuclear physics,including for photocurrent signals and transistor leakage *** could also become a key component of a portable mode-localized multimeter when combined with a mode-localized *** addition,it has the potential for use in studying sensor arrays to achieve higher resolution.

关键词： mode weakly resonator

Local Buckling-Induced Forming Method to Produce Metal Bellows

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Mechanical Engineering 2023年第1期36卷 104-114页

作者： Tianyin Zhang dongqing Li Tianjiao Xu Yongfeng Sui Xianhong han Institute of Forming Technology&Equipment School of Materials Science and EngineeringShanghai Jiao Tong UniversityShanghai200030China hangzhou Steam Turbine&Power Group Co. LtdHangzhou310100China National Engineering Research Center of Die and Mold CAD Shanghai Jiao Tong UniversityShanghai200030China

A novel buckling-induced forming method is proposed to produce metal *** tube billet is firstly treated by local heating and cooling,and the axial loading is applied on both ends of the tube,then the buckling occurs at the designated position and forms a *** this paper,a forming apparatus is designed and developed to produce both discontinuous and continuous bellows of 304 stainless steel,and their characteristics are discussed ***,the influences of process parameters and geometric parameters on the final convolution profile are deeply studied based on FEM *** results suggest that the steel bellows fabricated by the presented buckling-induced forming method have a uniform shape and no obvious reduction of wall ***,the forming force required in the process is quite small.

关键词： Buckling-induced forming Dieless No wall-thinning Stainless-steel bellows