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Design Schemes and Comparison Research of the End-effector of Large Space Manipulator

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Chinese Journal of Mechanical Engineering 2012年第4期25卷 674-687页

作者： FENG fei liu Yiwei liu Hong CAI Hegao State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin 150080 China

The end-effector of the large space manipulator is employed to assist the manipulator in handling and manipulating large payloads on ***,there are few researches about the end-effector,and the existing end-effectors have some disadvantages,such as poor misalignment tolerance capability and complex mechanical *** to the end positioning errors and the residual vibration characters of the large space manipulators,two basic performance requirements of the end-effector which include the capabilities of misalignment tolerance and soft capture are *** the end-effector should accommodate the following misalignments of the mechanical *** translation misalignments in axial and radial directions and the angular misalignments in roll,pitch and yaw are ±100 mm,100 mm,±10°,±15°,±15°,*** end-effector schemes are presented and the capabilities of misalignment tolerance and soft capture are analyzed *** three fingers-three petals end-effector and the steel cable-snared end-effector are the most feasible schemes among the seven schemes,and they are designed in *** capabilities of misalignment tolerance and soft capture are validated and evaluated,through the experiment on the micro-gravity simulating device and the dynamic analysis in ADAMS *** results show that the misalignment tolerance capabilities of these two schemes could satisfy the *** the translation misalignment tolerances in axial and radial directions and the angular misalignment tolerances in roll,pitch and yaw of the steel cable-snared end-effector are 30mm,15mm,6°,3° and 3° larger than those of the three fingers-three petals end-effector,*** the contact force of the steel cable-snared end-effector is smaller and smoother than that of the three fingers-three petals *** end-effector schemes and research methods are beneficial to the developments of the large space manipulator end-effctor and t

关键词： end-effector large space manipulator docking mechanism soft capture misalignment tolerance passive compliance active compliance

Safety assessment of approximate segregated parallel operation on closely spaced parallel runways

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Chinese Journal of Aeronautics 2019年第2期32卷 463-476页

作者： fei liu Xinze liu Mingjiang MOU Zhiqiang WEI Air Traffic Management College Civil Aviation University of China

With the continuous growth of air traffic flow, some airports in China or other countries begin to construct Closely Spaced Parallel Runways(CSPR) to meet the capacity requirement of civil aviation. In this paper, the simulation and calculation method of flight trajectory is developed,as well as the collision risk calculation method and wake vortex encounter risk calculation *** methods for departure and go-around procedures are proposed to achieve approximate segregated parallel operation in an attempt to obtain approximately the same results on closely spaced parallel runways as on widely spaced parallel runways. By comparing with the independent parallel departure and segregated parallel operation in ICAO Doc. 9643, it is found that the lateral separation between aircraft in this proposal is not less than the separations in the other two cases. Based on the simulation calculation of flight trajectories under different conditions, the probabilities of collision conflict and encountering wake vortex are lower than those in current operation *** proposed plan has no special requirements in pilot operation, control command procedures,airport facilities, or meteorological observation and prediction, so it is convenient to promote and implement at the airports with closely spaced parallel runways.

关键词： Air traffic control Air transportation Closely spaced parallel runways Segregated parallel operation Wake vortex encounter Wake vortex separation standards

Influence of the finish rolling temperatures on the microstructure and texture evolution in the ferritic stainless steels

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Acta Metallurgica Sinica(English Letters) 2011年第5期24卷 343-350页

作者： fei GAO Zhenyu liu Haitao liu Guodong WANG The State Key Laboratory of Rolling and Automation Northeastern University Shenyang 110819 China

The influence of the finish rolling temperature on the microstructure and texture evolution of Nb and B micro-alloyed ultra purified Cr17 ferritic stainless steels was investigated. The hot rolled bands were produced by conventional rolling process and the finish rolling at relatively low temperatures or ＂warm rolling＂. The microstructure was observed by optical microscopy, scanning electron microscopy and transmission electron microscopy, and X-ray diffraction was used to characterize the texture evolution processes. The results showed that as compared to conventional hot rolling process, the warm rolling has led to the refined and homogeneous microstructure and uniform recrystallization texture along γ-fiber in final sheets, indicating that the finish rolling at relatively low temperatures can be the effective way to improve significantly the formability of final sheets.

关键词： Ultra purified Cr17 ferritic stainless steel Finish rolling temperature Microstructure Texture

The Unsteady Fluctuating Pressure and Velocity in a Cross Flow Fan

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Journal of Thermal Science 2008年第4期17卷 349-355页

作者： Jiaye Gan fei liu Min liu Keqi Wu State Key Laboratory of Coal Combustion Huazhong University of Science and Technology Wuhan 430074 Chinaganjiaye0775 @ ***

This paper investigates the relations between the fluctuating pressure and velocity of the source by means of nu- merical method and sound pressure in the far field obtained with an noise experiment for a novel cross flow fan. The frequency characteristics of the fluctuating pressure and velocity in a cross flow fan are analyzed by means of spectral analysis and wavelet transform. The fluctuating pressures obtained by large eddy simulation on the casing wall are compared with that of experiments and show good agreement. From the spectral analysis of sound source, it is found that the pressure fluctuating peak is correspond with the sound pressure in the far field.

关键词： cross flow fan spectral analysis aerodynamic noise

An improved quaternion Gauss–Newton algorithm for attitude determination using magnetometer and accelerometer

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Chinese Journal of Aeronautics 2014年第4期27卷 986-993页

作者： liu fei Li Jie Wang Haifu liu Chang School of Mechatronical Engineering Beijing Institute of Technology

For the vector attitude determination, the traditional optimal algorithms which are based on quaternion estimator（QUEST） measurement noise model are complicated for just two observations. In our application, the magnetometer and accelerometer are not two comparable kinds of sensors and both are not small field-of-view sensors as well. So in this paper a new unit measurement model is derived. According to the Wahba problem, the optimal weights for each measurement are obtained by the error variance researches. Then an improved quaternion Gauss–Newton method is presented and adopted to acquire attitude. Eventually, simulation results and experimental validation employed to test the proposed method demonstrate the usefulness of the improved algorithm.

关键词： Accelerometer Attitude determination Gauss-Newton algorithm Magnetometer Measurements

Electrical switching of spin-polarized current in multiferroic tunneling junctions

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npj Computational Materials 2022年第1期8卷 1877-1885页

作者： Ligong Zhang Yuchen Wang Xiaoyan liu fei liu School of Integrated Circuits Peking University100871BeijingChina Beijing Advanced Innovation Center for Integrated Circuits 100871BeijingChina

The generation and manipulation of spin-polarized current are critical for spintronic *** this work,we propose a mechanism to generate and switch spin-polarized current by an electric field in multiferroic tunnel junctions(MFTJs),with symmetric interface terminations in an antiparallel magnetic *** such devices,different spin tunneling barriers are realized by the magnetoelectric coupling effect,resulting in a spin-polarized *** reversing the electric polarization of the ferroelectric layer,the spin polarization of current is efficiently switched for the exchange of spin tunneling *** first-principles quantum transport calculations,we show that a highly spin-polarized current is obtained and manipulated by the electric field in hafnia-based MFTJs based on the proposed *** also demonstrate that four resistance states are realized in Co/HfO_(2)/Co junctions with asymmetric interface *** work provides a promising approach for realizing the electrical control of spin current for spintronic applications.

关键词： mechanism. polarized tunneling

Monitoring Computer Numerical Control Machining Progress Based on Information Fusion

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Chinese Journal of Mechanical Engineering 2011年第6期24卷 1074-1082页

作者： TONG Liang YAN Ping liu fei State Key Laboratory of Mechanical Transmission Chongqing UniversityChongqing 400030China Chongqing Engineering Research Center of Networked Manufacturing Chongqing UniversityChongqing 400030China

To cope with the market demand dynamically,enterprise needs to obtain the production status of work in process real-timely,but the information of machining progress has feature of uncertainty and can not reflect the status of production field *** this work,to overcome the ineffectiveness of computer numerical control(CNC) machining progress information extraction and its application restriction in practice because of heterogeneous system of CNC machine,based on information fusion by analyzing multi-sources information,estimating CNC machining status and predicting the machining progress through tracking tool coordinates,a CNC machining progress monitoring method is *** multi-sources heterogeneous information includes machining path,real-time spindle power information,manual input data and tool *** the method of obtaining this multi-sources heterogeneous information,the method which helps explore numerical control(NC) program,monitor spindle power of CNC,collect human-computer interaction(HCI) information,obtain real-time tool coordinates and express the knowledge concerned in this field is analyzed; The decision rule of CNC machining status in the way of fusing multi-sources information in manufacturing process is summarized,as well as the machining progress tracking method in accordance with real-time tool coordinates and machining path is ***,the method discussed is proved feasible by the verification of machining progress tracking through simulation *** proposed research realizes the effective integration of CNC machining progress information,and enables enterprises an efficient way to share CNC information and configure CNC resources optimally.

关键词： machining progress information fusion machining path CNC machining process track

Analyses of mechanically-assembled 3D spiral mesostructures with applications as tunable inductors

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Science China(Technological Sciences) 2019年第2期62卷 243-251页

作者： ZHANG Fan liu fei ZHANG YiHui Key Laboratory of Applied Mechanics of Ministry of Education Department of Engineering Mechanics Tsinghua University Center for Flexible Electronics Technology and Center for Mechanics and Materials Tsinghua University

Mechanically-guided assembly allows the formation of 3D spiral-shaped inductors through controlled buckling, which could provide an increased quality(Q) factor and broadened working angle in near field communication, as compared to the planar design. An understanding of the microstructure-property relationship is essential in the design optimization of the assembly process. This work presents a theoretical model to analyze the deformations during the assembly of the 3D spiral-shaped mesostructure from a bilayer precursor that consists of a supporting ribbon and a 2D coil on its top. As validated by both the experiments and finite element analyses(FEA), this mechanics model allows accurate predictions of the assembled 3D configurations. In combination of electromagnetic simulations, we investigated the effects of various key design parameters on the final 3D configuration and the Q factor when operated as an inductor. The results suggest a significant role of the gravity effect on the assembled spiral configuration, especially for flexible coil designs with relative small cross-sectional areas or long *** study can serve as a reference for the design of spiral-shaped 3D inductors in different device applications.

关键词： 3D assembly modeling buckling multilayer tunable inductor

SHARING AND PLANNING OF DISTRIBUTED EQUIPMENT FOR NETWORKED MANUFACTURING

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Chinese Journal of Mechanical Engineering 2007年第1期20卷 73-76页

作者： CAO Le liu fei School of Mechanical Engineenng Chongqing University Chongqing 400030 China

Efficient utilization of the equipment distributed in different enterprises and optimal allocation of these resources is an important concern for networked manufacturing. The third party based equipment sharing approach is put forward to optimize the utilization of distributed equipment for networked manufacturing; Taking advantage of the shared equipment offered by equipment providers by means of lease agreement, the third party carries out production by establishing networked virtual factory. Operational mechanism of the third party based equipment sharing is discussed, and characteristics of this approach in achieving resource allocation are analyzed. Shared equipment planning is formulated as an optimization problem with the objective of maximizing profits for equipment coordinator, a mathematical model for shared equipment planning is developed. Finally a case study is discussed to show the effectiveness of the planning model.

关键词： Networked manufacturing Equipment sharing Equipment planning