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Chinese Journal of Aeronautics 2021年第4期34卷 192-207页

作者： Tingzhang WANG Henan LIU Chunya WU Jian CHEN Mingjun CHEN Center for Precision Engineering Harbin Institute of TechnologyHarbin 150001China

As for ultra-precision grinding of difficult-to-process thin-walled complex components with ball-end grinding wheels,interference is easy to occur.According to screw theory and grinding kinematics,a mathematical model is established to investigate the interference and grinding characteristics of the ball-end wheel.The relationship between grinding wheel inclination angle,C axis rotation angle,grinding position angle and grinding wheel wear are analyzed.As the grinding wheel inclination angle increases,the C axis rotatable range decreases and the grinding position angle increases.The grinding position angle and wheel radius wear show a negative correlation with the C axis rotation angle.Therefore,a trajectory planning criteria for increasing grinding speed as much as possible under the premise of avoiding interference is proposed to design the grinding trajectory.Then grinding point distribution on the ball-end wheel is calculated,and the grinding characteristics,grinding speed and maximum undeformed chip thickness,are investigated.Finally,a complex structural component can be ground without interference,and surface roughness and profile accuracy are improved to 40.2 nm and 0.399 lm,compared with 556 nm and 3.427 lm before ultra-precision grinding.The mathematical model can provide theoretical guidance for the analysis of interference and grinding characteristics in complex components grinding to improve its grinding quality.

关键词： Ultra-precision grinding Complex component Ball-end grinding wheel interference Grinding characteristics

interference torque of a three-floated gyroscope with gas-lubricated bearings subject to a sudden change of the specific force

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Chinese Journal of Aeronautics 2019年第3期32卷 737-747页

作者： Yan LI Fuhai DUAN School of Mechanical Engineering Dalian University of Technology

A numerical study is carried out to investigate the influence of a sudden change of the specific force on a three-floated gyroscope with a rotor supported on gas-lubricated bearings.The interference torque is calculated to evaluate the influence by modeling the transient behavior of the rotor-bearing system. In combination with dynamic equations of the rotor displacement,the Reynolds equation is solved on the surface of spiral-grooved conical bearings. It is assumed that a steady state has been obtained with a constant specific force, and then the specific force is suddenly changed and maintained constant after that. Responses of the sudden change are obtained by solving the equations. Numerical results show that the direction of the sudden change of the specific force is the main factor which influences the interference torque curve. With a sudden change along the input direction, the interference torque fluctuation has a constant frequency and a decreasing amplitude. With a sudden change along the output direction, the interference torque fluctuates in a small range. With a sudden change along the spin direction, the change of the interference torque combines a fluctuation and a gradually-changing quasi-equilibrium value. This study provides a supplement to the steady-state error model of the three-floated gyroscope.

关键词： Conical bearing Gas lubricated bearings interference torque Rotor-bearing system Three-floated gyroscope

interference mechanism analysis and mitigation measures with railway signalling equipment from harmonics in the traction system

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Transportation Safety and Environment 2020年第4期2卷 271-282页

作者： Zhiyu Li Shanghe Liu Shijiazhuang Tiedao University Shijiazhuang 050043China CRSC Research&Design Institute Group Co. Ltd.Beijing 100070China

With the development of high-speed railway and heavy-haul rail transport in China,a large number of new types of electric locomotives and electric multiple units have been put into operation,improving the efficiency and equipment quality of railway transportation.However,harmonics emitted from the traction system and locomotives often interfere with the railway signalling equipment,which can lead to critical malfunction of the equipment.Based on field test data,this paper analyses the interference coupling mechanism and magnitude of traction harmonics to the signalling equipment using a three-element method of interference.It examines the three essential elements of electromagnetic interference,studies harmonic mitigation measures and proposes to solve the problem of inteference with signalling equipment by installing a passive high-pass filter in the coupling path.After comparing the effects of several types of filters using simulation tests,this paper verified the validity of the method and concluded that a second-order passive filter is the optimal solution for harmonic interference mitigation.

关键词： heavy-haul railway traction harmonics interference signalling equipment

interference Cancellation in Device-to-Device Communications underlying MU-MIMO Cellular Networks

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China Communications 2019年第4期16卷 75-88页

作者： Yiyang Ni Yuxi Wang Hongbo Zhu Jiangsu Key Laboratory of Wireless Communications Nanjing University of Posts and Telecommunications Jiangsu Second Normal University

This paper investigates the device-to-device(D2 D) communication underlaying multi-user multi-input multi-output(MU-MIMO) cellular networks. It is assumed that D2 D users reuse the downlink time-frequency resources of cellular links, and the base station(BS) is assumed to be equipped with multiple antennas. We investigate the ergodic achievable sum rate of the system when the interference cancellation(IC) precoding strategy is employed at the BS. The distributions of the received signal-to-interference-plus-noise ratio(SINR) for each link are firstly analyzed, and an exact ergodic achievable sum rate of the whole system with closedform expressions is then derived. Furthermore, we present novel upper and lower bounds with simpler expressions, which are later verified to be fairly close to the Monte-Carlo simulations. All the expressions we presented are suitable for arbitrary network topology and arbitrary number of antennas at BS. Based on the derived bounds, the influence of the antennas at BS on system performance is then analyzed. We reveal that the system performance increases along with the number of antennas at BS in a logarithmic way. The accuracy of our analytical results is validated via comparisons with Monte-Carlo simulations.

关键词： interference cancellation D2D communication ergodic achievable sum rate MU-MIMO

interference Coordination for FD-MIMO Cellular Network with D2D Communications Underlaying

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China Communications 2018年第12期15卷 75-88页

作者： Xiao Li Nana Qin Tingting Sun National Mobile Communications Research Laboratory Southeast University

In this paper, we investigate the interference coordination for downlink full-dimension multiple-input multiple-output(FD-MIMO) systems with device-to-device(D2 D) communications underlaying. With three-dimensional(3 D) beamforming transmission applied for cellular users(CUEs), an approximation of the interference to signal ratio for CUEs is derived, and a coordination strategy is proposed to mitigate the interference from D2 D pairs to CUEs. Based on the lower bound of the interference to signal ratio for D2 D pairs, we propose coordination strategies for D2 D pairs to mitigate the interference caused by base station(BS) and the interference between D2 D pairs. The proposed strategies require only some statistical channel state information(CSI) of each user and the reduced-dimensional effective CSI of a few CUEs and D2 D pairs. Simulation results show that the proposed coordination strategy performs well in terms of achieving good tradeoff between the achievable rate of CUEs and D2 D pairs.

关键词： D2D FD-MIMO 3D beamforming interference coordination

interference-Driven Designs of Nonlinear-Phase FIR Filter with Application in FBMC System

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China Communications 2016年第12期13卷 15-24页

作者： Jiangang Wen Jingyu Hua Sunan Li Kai Zhou Dongming Wang College of Information Engineering Zhejiang University of Technology Zhejiang Key Lab.Commun.Network&Appl. Zhejiang Univ.Tech. National Mobile Communication Research Laboratory Southeast University

In the forthcoming 5G systems, new technologies, such as amorphous networks and non-orthogonal filter bank multicarriers(FBMC), provide an effective way to accommodate high-rate transmissions. Meanwhile, the prototype filter affects the adjacent channel interference, and therefore is important for FBMC systems. Besides, once the amorphous network is taken into account, the requirement for interference controlmust be much stricter. Accordingly, this paper focuses on the design of prototype filter with better ability of interference controlling, where we exploit the nonlinear phase FIR filter(NLPFF) instead of traditional linear phase FIR filter(LPFF) to achieve more optimization spaces under a small sacrifice of linear phase. In ourdesigns, both the amplitude and phase responsesare handled independently to approach the stopband performance enhancements, in while the nearly perfect reconstruction(NPR) conditionsare relaxed by pre-specified thresholds. Computer simulations confirm the effectiveness of the NLPFF designs, and demonstrate the advantages of the proposed NLPFF in FBMC applications.

关键词： constrained minimax constrained least-square FBMC nonlinear-phase filter interference

Intelligent interference Management and Secure Communications for Satellite-Terrestrial Integrated Systems

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China Communications 2022年第7期19卷 I0002-I0004页

作者： Lidong Zhu Michele Luglio Gengxin Zhang Mingchuan Yang University of Electronic Science and Technology of China 不详 Nanjing University of Posts and Telecommunications NanjingChina Communication Research Center Harbin Institute of Technology China

Satellite-terrestrial integrated(STI)systems represent the right solution to meet complex requirements of several services and sharing of the limited spectral resources between satellite systems and terrestrial ones must be considered to optimize performance.Network architectures and traffic demand are different for the satellite component and for the terrestrial 5G/6G one,so that the requirements of spectral resources for satellite and terrestrial systems are expected to vary dynamically in a significant range.

关键词： terrestrial Communications interference

Flexible and transparent graphene/silver-nanowires composite ?lm for high electromagnetic interference shielding effectiveness

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Science Bulletin 2019年第8期64卷 540-546页

作者： Ning Zhang Zhe Wang Rongguo Song Qianlong Wang Hongye Chen Bin Zhang Haifei Lv Zhi Wu Daping He Hubei Engineering Research Center of RF-Microwave Technology and Application School of Science Wuhan University of Technology Shenzhen Institute of Advanced Graphene Application and Technology (SIAGAT)

Herein, an efficient approach to prepare flexible, transparent, and lightweight films based on graphene nanosheets(GNS) and silver nanowires(AgNWs) for high electromagnetic interference(EMI) shielding effectiveness(SE) has been explained. High-conductive GNS were fabricated by liquid phase stripping and composited with AgNWs by a two-step spin-coating method. Owing to the high transparency, good conductivity, and homogeneous distribution of both GNS and AgNWs, the obtained GNS/AgNWs film exhibits superb EMI SE and light transmittance, yielding a significantly high EMI SE up to 26 dB in both Ku-band and K-band and light transmittance higher than 78.4%. Moreover, this GNS/AgNWs film shows good flexibility and excellent structural stability. The obtained flexible, light and transparent film could have a great potential for transparent EMI shielding and smart electronics.

关键词： Flexibility Transparent Electromagnetic interference shielding Graphene Silver nanowires

An Intelligent Optimization Approach to Non-stationary interference Suppression for Wireless Networks

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IEEE/CAA Journal of Automatica Sinica 2019年第2期6卷 452-459页

作者： Lichuan Liu the Department of Electrical Engineering Northern Illinois University

In this paper, we propose a new technique to effectively suppress non-stationary interference signal for wireless networks. This technique combines a new scheme of interference signal estimation with the intelligent optimization projection. In order to capture interference signal's subspace, a time-varying method is used to estimate the non-stationary interference.Orthogonal polynomials are used for the basis function instead of the power of the time to reduce the computational complexity.The interference is then removed from the corrupted signal by subspace projection, resulting in less distortion to the desired signal. The performance of this approach is validated by computer simulation.

关键词： interference non-stationary projection suppression time-varying wireless networks

Larval interference competition between the native Neotropical mosquito Limatus durhamii and the invasive Aedes aegypti improves the fitness of both species

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Insect Science 2018年第6期25卷 1102-1107页

作者： Stanislas Talaga Alain Dejean Clémence Mouza Yves Dumont Céline Leroy lnsUtut Pasteur de la Guyane Unitéd'Entomologie MédicaleCayenne cedexFrance CNRS UMR EcoFoGAgroParisTechCiradINRAUniversitédes AntillesUniversitéde GuyaneKourouFrance CNRS INPTUPSEcolabUniversitéde ToulouseToulouseFrance AMAP CIRADCNRSINRAIRDUniversit6MontpellierMontpellierFrance

Interspecific competition with native species during biological invasions can sometimes limit alien expansion.We aimed to determine the potential ecological effects of Limatus durhamii Theobald 1901,a native Neotropical mosquito (Diptera:Culicidae) species,on the invasive species Aedes (Stegomyia)aegypti (Linnaeus 1762)that breeds in the same artificial water containers.Development time and adult dry mass were measured in 3 rearing conditions:control (a single larva),intraspecific competition (2 conspecific larvae),and interspecific competition (2 heterospecific larvae).Food was provided ad libitum to eliminate exploitative competition.For Ae.aegypti,development time was not affected by interspecific interference competition (nonsignificant differences with the control)and the adult dry mass was significantly higher,meaning that individual fitness likely increased.Yet,because previous studies showed longer development time and lighter adults during competition with other invasive mosquitoes,it is likely that Ae.aegypti can express a different phenotype depending on the competing species.The similar pattern found for Li.durhamii females and the nonsignificant difference with the control for males explain in part why this species can compete with Ae.aegypti.

关键词： Aedes aegypti increased fitness interference competition Limatus durhamii phenotypic plasticity resistance to invasion