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Studyon Evaluation Methods for Lateral Stability of High-Speed Trains

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中国铁道科学 2012年第6期33卷 132-139页

作者： YAO jianwei sun Lixia HOU Fuguo Railway Science and Technology Research and Development Center China Academy of Railway Sciences Beijing 100081 China

Taking a high-speed train in China as an example,using computer simulation technology and comparing with the test data,the three current methods including linear stability analysis method,nonlinear stability analysis method and the field testing criterion are studied to evaluate stability of high-speed trains.A new stability evaluation method is proposed which can be used to evaluate lateral stability of high-speed vehicle based on the codes of UIC 515and UIC *** the viewpoint of taking the most unfavorable track conditions into account and improving the safety margin,the new method uses the root mean square of bogie lateral acceleration as a criterion to evaluate the lateral stability of high-speed *** example shows that the proposed method not only considers the forced vibration caused by track irregularities in the actual practice,but also takes the instability self-excited vibration into account,so it can realize early warning of bogie slight unstable oscillation,meanwhile the method itself does not involve complex algorithms which has the possibility of engineering applications.

关键词： High-speed train Lateral stability Critical speed Evaluation method

Passive target tracking using marginalized particle filter

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Journal of Systems Engineering and Electronics 2007年第3期18卷 503-508页

作者： Zhan Ronghui Wang Ling Wan jianwei sun Zhongkang School of Electronic Science and Engineering National Univ. of Defense Technology Changsha 410073 P. R. China

A marginalized particle filtering （MPF） approach is proposed for target tracking under the background of passive measurement. Essentially, the MPF is a combination of particle filtering technique and Kalman filter. By making full use of marginalization, the distributions of the tractable linear part of the total state variables are updated analytically using Kalman filter, and only the lower-dimensional nonlinear state variable needs to be dealt with using particle filter. Simulation studies are performed on an illustrative example, and the results show that the MPF method leads to a significant reduction of the tracking errors when compared with the direct particle implementation. Real data test results also validate the effectiveness of the presented method.

关键词： nonlinear filtering passive target tracking particle filter marginalized particle filter state estimation.

Achieving Physical Layer Security Against Location Unknown Eavesdroppers via Friendly Jammer

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IEEE/CAA Journal of Automatica Sinica 2023年第10期10卷 2038-2040页

作者： Heng Zhang jianwei sun Xin Wang Chenglong Gong School of Computer Engineering Jiangsu Ocean UniversityLianyungang 222000China School of Electronic Engineering Jiangsu Ocean UniversityLianyungang 222000China Shandong Provincial Key Laboratory of Computer Networks Shandong Computer Science CenterQilu University of TechnologyJinan 250014China

Dear Editor, This letter is concerning friendly jamming unmanned aerial vehicles(UAVs) to assist in the safe communication of UAV base stations. Due to the openness of UAV wireless communication, it is vulnerable to attacks leading to information disclosure or blockage. To address this issue, friendly jamming UAVs can assist UAV base stations and improve the security of wireless communications.

关键词： communication letter base

Residual Stress Distribution of Si_(3)N_(4)/SiC Gradient Material and the Effect of Residual Stress on Material Properties

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Journal of Wuhan University of Technology(Materials Science) 2023年第4期38卷 759-765页

作者：赵东升 JING Qiang sun jianwei 张金咏 State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of TechnologyWuhan430070China

The Si_(3)N_(4)/SiC gradient material with a gradient composition structure was prepared by a hot pressing *** sinterability,distribution of residual stress and the effect of residual stress on mechanical properties of Si_(3)N_(4)/SiC gradient materials were *** research results show that,at 1750℃,Si_(3)N_(4)/SiC gradient materials with different ratios can achieve co-sintering,and the overall relative density of the sample reaches 98.5%.Interestingly,the flexural strength of Si_(3)N_(4)/SiC gradient material is related to its loading *** flexural strength of SiC as the loading surface is about 35%higher than that of Si_(3)N_(4)as the loading *** analysis of the residual stress of the material in the gradient structure shows that the gradient stress distribution between the two phases is a vital factor affecting the mechanical properties of the *** the increase of SiC content in the gradient direction,the fracture toughness of each layer of Si_(3)N_(4)/SiC gradient materials gradually *** surface hardness of the pure SiC side is lower than that reported in other literature.

关键词： Si_(3)N_(4) SiC gradient material residual stress mechanical properties

Comparative first-principles study of elastic constants of covalent and ionic materials with LDA,GGA,and meta-GGA functionals and the prediction of mechanical hardness

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Science China(Technological Sciences) 2021年第12期64卷 2755-2761页

作者： XING WanDong MENG FanYan NING JinLiang sun jianwei YU Rong Department of Physics University of Science and Technology BeijingBeijing 100083China National Center for Electron Microscopy in Beijing School of Materials Science and EngineeringTsinghua UniversityBeijing 100084China Department of Physics and Engineering Physics Tulane UniversityNew OrleansLA 70118USA

Accurate prediction of single-crystal elastic constants is critical for materials design and for understanding phase transition and elastic interactions in *** this work,the accuracy of elastic constants calculated with three density functional approximations has been compared,including the local density approximation(LDA),the generalized gradient approximation(GGA),and the recently developed strongly constrained and appropriately normed(SCAN)*** results show that SCAN and PBE describe elastic constants better than *** strong correlation between the mechanical hardness and the stiffness of the softest eigenmode(SSE)has been given for above three density *** correlation is capable of predicting accurately the hardness of covalent,ionic,and mixed covalent-ionic crystals,and providing us a convenient indicator for the discovery of hard or superhard materials.

关键词： hardness indicator elastic constants stiffness of softest eigenmode superhard materials

Design method for a bionic wrist based on tensegrity structures

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Biosurface and Biotribology 2020年第2期6卷 31-36页

作者： jianwei sun Xuemin Cao Guangsheng Song School of Mechanical Engineering Chang Chun University of TechnologyJilin 130012People’s Republic of China Key Laboratory for Terrain-machine Bionics Engineering Jilin UniversityRenMinStreet 5988Changchun130022 JilinPeople’s Republic of China

The traditional bionic upper limb structure design is limited by the motion pair and cannot guarantee the flexibility of the mechanical *** tensegrity structure has the characteristics of high deformability,strong self-adaptability,and resistance to multi-directional *** to the biological characteristics of the upper limbs of the human body,an anatomical study is performed on the upper limb wrist joints that achieve adduction/abduction,flexion/extension,to obtain the relationship between the movements of the related bones and muscles,and to simplify the shape and structure of the *** mapping of a mechanical model based on two-bar tensile *** the contraction and stretching of the spring,the movement characteristics of the human muscles are realised,and the optimised bionic upper limb wrist tensioning robot without motion pair is further *** simulation is used to verify that the bionic tensile wrist can simulate the change movement of the human *** experimental platform was built and a physical prototype was made and the prototype was *** results show that the bionic tensile wrist can realise the adaptive motion characteristics of the human wrist well and stably,which proves the validity and feasibility of this design method.

关键词： ionic structure stretching

Chiral phosphoric acid-catalyzed regio- and enantioselective reactions of functionalized propargylic alcohols

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Organic Chemistry Frontiers 2022年第5期9卷 1234-1240页

作者： Chenxiao Qian Meiwen Liu jianwei sun Pengfei Li Shenzhen Grubbs Institute and Department of Chemistry Guangdong Provincial Key Laboratory of CatalysisCollege of ScienceSouthern University of Science and TechnologyShenzhenGuangdong518055China Department of Chemistry The Hong Kong University of Science and TechnologyClear Water BayKowloonHong Kong SARChina

Propargylic alcohols have been known as useful substrates in a wide range of asymmetric *** particular,chiral phosphoric acid(CPA)catalyzed reactions of functionalized propargylic alcohols have opened robust access to... 详细信息

关键词： alcohols catalyzed chiral

Electrochemical synthesis of β-hydroxy-, β-alkoxy-, and β-carbonyloxy sulfones by vicinal difunctionalization of olefins

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Chinese Chemical Letters 2019年第8期30卷 1509-1511页

作者： Zhefan Zhang Jiyao Yan Dengke Ma jianwei sun Shenzhen Research Institute The Hong Kong University of Science and Technology(HKUST)Shenzhen 518057China Department of Chemistry The Hong Kong University of Science and Technology(HKUST)Hong KongChina

An electrochemical vicinal heterodifunctionalization of olefins for the synthesis ofβ-oxysulfones is *** suitable choice of the conditions,including current,electrodes,and electrolyte,this oxidation reaction proceeded efficiently in an undivided cell without the use of a stoichiometric chemical *** addition to the previously established synthesis ofβ-hydroxysulfones in the presence of water,minor modification of this protocol by using either external alcohol nucleophiles or internal carboxylic acid nucleophile also led to the synthesis ofβ-alkoxysulfones,andβ-sulfonyl lactones.

关键词： Olefins Difunctionalization Electrochemical synthesis Sulfones

Intelligent optimization methods of phase-modulation waveform

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Journal of Systems Engineering and Electronics 2022年第4期33卷 916-923页

作者： sun jianwei WANG Chao SHI Qingzhan REN Wenbo YAO Zekun YUAN Naichang College of Electronic Science and Technology National University of Defense TechnologyChangsha 410073China State Key Laboratory of Complex Electromagnetic Environment Effects on Electronics and Information System National University of Defense TechnologyChangsha 410073China

With the continuous improvement of radar intelligence, it is difficult for traditional countermeasures to achieve ideal results. In order to deal with complex, changeable, and unknown threat signals in the complex electromagnetic environment, a waveform intelligent optimization model based on intelligent optimization algorithm is proposed. By virtue of the universality and fast running speed of the intelligent optimization algorithm, the model can optimize the parameters used to synthesize the countermeasure waveform according to different external signals, so as to improve the countermeasure *** algorithm(GA) and particle swarm optimization(PSO)are used to simulate the intelligent optimization of interruptedsampling and phase-modulation repeater waveform. The experimental results under different radar signal conditions show that the scheme is feasible. The performance comparison between the algorithms and some problems in the experimental results also provide a certain reference for the follow-up work.

关键词： waveform optimization intelligent optimization phase-modulation genetic algorithm(GA) particle swarm optimization(PSO)