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Parameter Optimization of a Stability-Training Platform's 4-PSS/PS Parallel Mechanism Based on Training Ability Evaluation Index and PSO Algorithm

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Chinese Journal of Mechanical Engineering 2018年第3期31卷 37-47页

作者： Wei-Guo Wu Li-yang gao School of Mechatronics Engineering Harbin Institute of Technology

The existing mechanism parameter optimization(MPO) method of parallel mechanisms only considers the workspace size and ignores contribution of each configuration's performance. So a novel MPO method is proposed for our serial?parallel mechanism platform,which is used in stability training of legged robots. Regarding the platform's parallel mechanism part,a 4?PSS/PS parallel mechanism,two object functions and three constraint conditions are defined to establish the MPO model. The first object function uses critical motion indexes of the moving platform. The second one uses derivative function of the defined disturbance Lagrange function. After analyzing stability?training require?ments of five existing legged robots,requirements of the platform's motion capability are given out. Regarding each proposed object function separately,the MPO model is solved by the particle swarm optimization(PSO) algorithm. Valid workspace boundaries corresponding to the optimization results are solved by a numerical method. The overall optimal solution is determined based on volume of the valid workspace. It is revealed that the two object functions result in similar optimization solutions,which shows that the proposed object functions can reflect the stability?training ability consistently. This paper proposes and verifies the established MPO model,which considers both the workspace size and configurations' performance evaluation.

关键词： Stability training 4?PSS/PS parallel mechanism Mechanism parameter optimization Singularity analysis Particle swarm optimization

Immunological and virological characteristics of human immunodeficiency virus type i superinfection： implications in vaccine design

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Frontiers of Medicine 2017年第4期11卷 480-489页

作者： yang gao Wen Tian Xiaoxu Han Feng gao Key Laboratory of AIDS Immunology of Nattonal Health and Famdy Plannmg Commtsston Department of Laboratory Medicme The First Affiliated Hospital China Medical University Shenyang 110001 China National Engineering Laboratory for AIDS Vaccine School of Life Sciences Jilin University Changehun 130012 China Department of Medicine Duke University Medical Center Durham NC 27710 USA

Superinfection is frequently detected among individuals infected by human immunodeficiency virus type I （HIV-1）. Superinfection occurs at similar frequencies at acute and chronic infection stages but less frequently than primary infection. This observation indicates that the immune responses elicited by natural HIV-1 infection may play a role in curb of superinfection; however, these responses are not sufficiently strong to completely prevent superinfection. Thus, a successful HIV-1 vaccine likely needs to induce more potent and broader immune responses than those elicited by primary infection. On the other hand, potent and broad neutralization responses are more often detected after superinfection than during monoinfection. This suggests that broadly neutralizing antibodies are more likely induced by sequential immunization of multiple different immunogens than with only one form of envelope glycoprotein immunogens. Understanding why the protection from superinfection by immunity induced by primary infection is insufficient and if superinfection can lead to cross-reactive immune responses will be highly informative for HIV-1 vaccine design.

关键词： human immunodeficiency virus type I superinfection incidence immtme response

Local Government Implicit Guarantees in China＇ s Farmland Financial System

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学术界 2015年第5期 302-307页

作者： gao yang School of Economics Shandong University Jinan Shandong 250100

With the massive and intensive development of the operation mode of rural land in China,the financing problem of the new rural land managers has gradually attracted more *** reasonable design of farmland financial system is of great importance to promote rural financial resource allocation *** paper chooses two types of measures of local government implicit guarantees which are commonly used in promoting rural land mortgage *** measures are establishing guarantee mechanism to provide guaranties to borrowers and purchasing debt assets from financial *** analysis framework is based on the financing ability theory of Holmstrom &*** shows that when considering the collateral disposal cost,the two measures both could contribute to expand the coverage of farmland financial ***,local government implicit guarantees also exists some negative *** suggestions of the paper are reducing the collateral disposal costs of farmland loan /encouraging the market-oriented guarantee institutions to enter the rural credit market further standardizing the operation of policy guarantee mechanism and making the use range of risk fund and disposal fund clear.

关键词：金融机构地方政府担保农地中国农村土地抵押贷款资源配置优化

Analysis of Topological Structure in Transiently Chaotic Neural Networks

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Acta Mathematicae Applicatae Sinica 2018年第3期34卷 610-621页

作者： yang gao Zuo-huan ZHENG Institute of Applied Mathematics Academy of Mathematics and Systems Science Chinese Academy of Sciences

Under the condition that the damping factor is between zero and one, chaotic dynamics is proved to exist in one-dimensional transiently chaotic neural networks by Li-Misiurewicz theorem. This result extends the previous result which is done under the condition that the damping factor is zero. Because the value of damping factor affects the speed of dynamical process of transiently chaotic neural networks, this result provides more complete theoretical basis for applications. Finally, two examples by numerical simulation are given to reinforce and illustrate this result.

关键词： transiently chaotic neural networks Li-Yorke chaos no division

Wiener Filtration Algorithm of an Ensemble Pulsar Timescale Based on a Power-law Model of Pulsar Power Spectrum

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Research in Astronomy and Astrophysics 2022年第10期22卷 129-140页

作者： Ting-gao yang Ming-Lei Tong Yu-Ping gao National Time Service Center Chinese Academy of SciencesXi'an 710600China Key Laboratory of Time and Frequency Primary Standards Chinese Academy of SciencesXi'an 71000China University of Chinese Academy of Sciences Beijing 100049China

An ensemble pulsar timescale derived from the traditional Wiener filtration still contains some high level *** improve this situation we developed a Wiener filtration algorithm of the ensemble pulsar timescale based on a power-law model of power spectrum for *** algorithm has three strengths:(1)mitigating spectral leakage between frequency bins for Fourier techniques;(2)using a power-law model for power spectrum;(3)signal realization in original residuals of data set by the power-law *** to improved algorithm we constructed an ensemble pulsar timescale EPT-TAI using timing data with respect to International Atomic Time(TAI)about 16 yr time span of ten pulsars from International Pulsar Timing Array second data release(version A).The results show that EPT-TAI detected correctly the differences TT(BIPM2015)-TAI between terrestrial time TT(BIPM2015)and *** frequency stabilityσzanalysis shows that EPT-TAI does not indicate red noise for 16 yr time interval,and fractional frequency stability for 8 yr and longer time intervals is slightly better than that of TT(BIPM2015)-*** for short time intervals of TT(BIPM2015)-TAI is better than that of EPT-TAI,but TT(BIPM2015)-TAI shows red noise for longer time *** the same algorithm we also derived an ensemble pulsar timescale EPT-TT(BIPM2015)with respect to TT(BIPM2015).The fractional frequency stability curve of EPT-TT(BIPM2015)shows similar characteristics as that of EPT-TAI but with slightly lower values.

关键词： (stars:)pulsars general-time-methods data analysis

Joint number and DOA estimation via the eigen-beam mCapon method for closely spaced sources

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Science China(Information Sciences) 2015年第12期58卷 217-219页

作者： gao yang XU Jia JIA Xin Academy of Equipment School of Information and Electronics Beijing Institute of Technology

Dear editor,The source number and direction of arrival(DOA)estimation are two important subjects in array signal processing[1,2].Many algorithms for estimating these parameters have been proposed in the past

关键词： DOA Joint number and DOA estimation via the eigen-beam mCapon method for closely spaced sources MUSIC

Creep rate sensitivities of materials by a depth-sensing indentation technique

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Journal of University of Science and Technology Beijing 2006年第4期13卷 308-312页

作者： yang gao Shengping Wen Feng Pan Laboratory of Advanced Materials Department of Materials Science and Engineering Tsinghua University Beijing 100084 China

The strain rate sensitivity to creep of single crystal Cu（110）, metal tantalum, and 128°Y-X LiNbO3 piezoelectric single crystal were measured at room temperature by MTS Nanoindenter XP. Among the three kinds of materials studied, Cu showed the highest degree of resistance to creep-induced deformation, which is followed by Ta, while the LiNbO3 single crystal deformed more readily than the others. The values of the steady-state strain rate sensitivities determined by the indentation methods are in the range of 0.002-0.006, 0.02-0.06 and 0.02-0.03 for Cu, Ta, and LiNbO3, respectively. The mechanisms for the indentation-induced creeping behavior and the factors that influenced the creeping are discussed.

关键词： indentation creep strain rate sensitivity copper tantalum LiNbO3 piezoelectric single crystal

Regioselective Polymerizations of α-Olefins with an α-Diamine Nickel Catalyst

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Chinese Journal of Polymer Science 2019年第10期37卷 959-965,I0003页

作者： Heng Liao Jie gao Liu Zhong Hai-yang gao Qing Wu School of Materials Science and Engineering PCFM Lab GD HPPC Lab Sun Yat-sen University

Polymerizations of linear α-olefins(CnH2n, CH2=CH―R, R = Cn-2) catalyzed by early transition metals typically afford amorphous polymers with alkyl chains(Cn-2), while chain-straightening polymerizations of α-olefins with nickel-based catalysts produce semicrystalline polyolefins. Polymerizations of various α-olefins were carried out using an α-diamine nickel catalyst with a significantly distorted chelating ring. The influences of temperature, monomer concentration, and chain length of α-olefins on polyolefin microstructure were examined in detail. The α-diamine nickel catalyst realized highly regioselective 2,1-insertion of α-olefins regardless of reaction temperature and monomer concentration. Increased chain length of α-olefins led to the formation of more linear *** polyolefins with high melting temperatures(Tm) were made from α-olefins through highly regioselective 2,1-insertion and precise chain-straightening.

关键词： Nickel catalyst α-Olefin Polymerization Regioselectivity Chain walking

A Quick Convex Hull Building Algorithm Based on Grid and Binary Tree

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Chinese Journal of Electronics 2015年第2期24卷 317-320页

作者： gao yang CHENG Yuhu WANG Xuesong School of Information and Electrical Engineering China University of Mining and Technology

A quick convex hull building algorithm using grid and binary tree is proposed for the minimum convex buidling of planar point set. Grids are used to assess and eliminate those interior points wihtout any contribution to convex hull building and points are sought in the boundary grid only so as to enhance the efficiency of algorithm. The minimum convex bull is built by taking such advantages of binary tree as quick, convenient and applicable for various point sets with different distributions, so as to resolve the description problem of concave point. The time complexity of the algorithm is low because of grid pretreatment. As the results of comparative expriment of random point and actual picture show, the proposed algorithm can obtain the best profile of 2D planar picture with minimum time, which is applicable for describing the shape of irregular convex-concave objects.

关键词： Convex hull Gird Binary tree Concave point Time complexity