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Molecular simulation study of the microstructures and properties of pyridinium ionic liquid[HPy][BF_(4)]mixed with acetonitrile

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原子与分子物理学报 2025年第4期42卷 27-32页

作者： xu jian-Qiang MA Zhao-Peng CHENG Si LIU Zhi-Cong ZHU Guang-Lai Department of Physics School of Physics and Electronic InformationAnhui Normal UniversityWuhu 241002China

The microstructures and thermodynamic properties of mixed systems comprising pyridinium ionic liquid[HPy][BF_(4)]and acetonitrile at different mole fractions were studied using molecular dynamics simulation in this *** following properties were determined:density,self-diffusion coefficient,excess molar volume,and radial distribution *** results show that with an increase in the mole fraction of[HPy][BF_(4)],the self-diffusion coefficient ***,the excess molar volume initially decreases,reaches a minimum,and then *** rules of radial distribution functions(RDFs)of characteristic atoms are *** increasing the mole fraction of[HPy][BF_(4)],the first peak of the RDFs of HA1-F decreases,while that of CT6-CT6 rises at first and then *** indicates that the solvent molecules affect the polar and non-polar regions of[HPy][BF_(4)]differently.

关键词： Pyridinium ionic liquids Thermodynamic properties Molecular dynamics simulation Radial distribution functions

An analytical method for studying double Hopf bifurcations induced by two delays in nonlinear differential systems

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Science China(Technological Sciences) 2020年第4期63卷 597-602页

作者： GE JuHong xu jian Department of Mathematics and Information Science Henan University of Economics and LawZhengzhou 450046China Shanghai Institute of Intelligent Science and Technology Tongji UniversityShanghai 200092China

An analytical method is introduced to investigate double Hopf bifurcations induced by two delays qualitatively and *** an illustrative example,the clear procedure is demonstrated to study delay-induced weak resonant double Hopf bifurcation in a nonlinear system with multiple *** two delays are close to double Hopf bifurcation point,all solutions derived from the bifurcation are classified qualitatively and expressed *** simulations are a good agreement with our theoretical analysis,and also already work in *** results show that our work in this paper proposes a simple and valid method for investigating delay-induced double Hopf *** important feature of our work is that the explicit expression of periodic solutions is easy to be obtained by solving algebraic equations.

关键词： analytical methods multiple delays double Hopf bifurcation the coexistence of periodic motion

Reductivity and bundle shifts

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Applied Mathematics(A Journal of Chinese Universities) 2019年第1期34卷 27-32页

作者： xu An-jian College of Science Chongqing University of Technology

For the Hardy space H_E^2(R) over a ?at unitary vector bundle E on a ?nitely connected domain R, let TE be the bundle shift as [3]. If B is a reductive algebra containing every operator ψ(TE) for any rational functi... 详细信息

关键词： reductivity bundle shift multiply-connected domain

Quantized innovations Kalman filter: stability and modification with scaling quantization

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Journal of Zhejiang University-Science C(Computers and Electronics) 2012年第2期13卷 118-130页

作者： jian xu jian-xun LI Sheng xu Science and Technology on Avionics Integration Laboratory Shanghai Jiao Tong UniversityShanghai 200240 MOE Key Laboratory of System Control and Information Processing Shanghai Jiao Tong UniversityShanghai 200240China School of Mechanical Engineering Shanghai Jiao Tong UniversityShanghai 200240China

The stability of quantized innovations Kalman filtering (QIKF) is analyzed. In the analysis, the correlation between quantization errors and measurement noises is considered. By taking the quantization errors as a random perturbation in the observation system, the QIKF for the original system is equivalent to a Kalman-like filtering for the equivalent state-observation system. Thus, the estimate error covariance matrix of QIKF can be more exactly analyzed. The boundedness of the estimate error covariance matrix of QIKF is obtained under some weak conditions. The design of the number of quantized levels is discussed to guarantee the stability of QIKF. To overcome the instability and divergence of QIKF when the number of quantization levels is small, we propose a Kalman filter using scaling quantized innovations. Numerical simulations show the validity of the theorems and algorithms.

关键词： Kalman filtering Quantized innovation Stability Scaling quantization Wireless sensor network

Role of late transition metals on pitting resistance of Zr-Ti-(Cu, Ni,Co)-Al bulk metallic glasses in 0.6 M NaCl aqueous solution

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Journal of Materials Science & Technology 2017年第11期33卷 1278-1288页

作者： Yu Li jian xu Shenyang National Laboratory for Materials Science Institute of Metal Research Chinese Academy of Sciences Graduate School University of Chinese Academy of Sciences

Four quanternary Zr-based bulk metallic glasses（BMGs）were selected,including the Zr_（46）Ti_2Cu_（45）Al_7,Zr_（61）Ti_2Cu_（25）Al_（12）,Zr_（55）Ti_4Ni_（22）Al_（19）and Zr_（55）Ti_2Co_（28）Al_（15）,due to their robust glass-forming ability and containing a single species of late transition metal（LTM）in *** pitting resistances in 0.6 M Na Cl aqueous solution were investigated to examine the role of LTM elements in the alloys,with electrochemical measurements,surface morphology observation and x-ray photoelectron spectrometry *** is shown that in comparision with two Cu-bearing BMGs,Zr_（55）Ti_4Ni_（22）Al_（19）and Zr_（55）Ti_2Co_（28）Al_（15）BMGs exhibited significantly superior resistance to ***_（61）Ti_2Cu_（25）Al_（12）,Zr_（55）Ti_4Ni_（22）Al_（19）and Zr_（55）Ti_2Co_（28）Al_（15）BMGs manifested distinct passivation behaviour,because of the formation of surface passive film mainly comprising of Zr O_2,Ti O_2and Al_2O_***,no significant differences in the electrochemical resistive properties and thicknesses of passive films were found between Zr_（61）Ti_2Cu_（25）Al_（12）and Zr_（55）Ti_4Ni_（22）Al_（19）***,at the passive film/metal interface,copper enrichment took place in Zr_（61）Ti_2Cu_（25）Al_（12）,whereas the nickel was slightly deficient at the interface in Zr_（55）Ti_4Ni_（22）Al_（19）.During pitting propagation,selective dissolution of the zirconium,titanium and aluminum over the copper took place in Zr_（61）Ti_2Cu_（25）Al_（12）,but it was not the case in Zr_（55）Ti_4Ni_（22）Al_（19）.For the two Cu-bearing BMGs,reduction of passive base metal elements in composition resulted in local selective dissolution,even absence of the passivation.

关键词： Bulk metallic glass Pitting corrosion Electrochemical behavior Passive film

Experimental studies on active control of a dynamic system via a time-delayed absorber

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Acta Mechanica Sinica 2015年第2期31卷 229-247页

作者： jian xu Yixia Sun School of Aerospace Engineering and Applied Mechanics Tongji University

The traditional passive absorber is fully effective within a narrow and certain frequency *** solve this problem,a time-delayed acceleration feedback is introduced to convert a passive absorber into an active *** the inherent and the intentional time delays are *** former mainly comes from signal acquiring and processing,computing,and applying the actuation force,and its value is *** latter is introduced in the controller,and its value is actively ***,the mechanical model is established and the frequency response equations are *** regions of stability are delineated in the plane of control ***,the design scheme of control parameters is performed to help select the values of the feedback gain and time ***,the experimental studies are *** of both negative and positive feedback control are *** results show that the proper choices of control parameters may broaden the effective frequency band of vibration ***,the time-delayed absorber greatly suppresses the resonant response of the primary system when the passive absorber totally *** experimental results are in good agreement with the theoretical predictions and numerical simulations.

关键词： Vibration absorber Time-delayed feedback Vibration control Stability

EXPLAINING THE CHANGES IN ALPS BY IDENTIFYING ALPS-IMPORTANT COEFFICIENTS:AN EMPIRICAL APPLICATION OF CHINA

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Journal of Systems Science & Complexity 2013年第3期26卷 383-406页

作者： LU Xiaolin xu jian Management School University of Chinese Academy of Sciences

This paper establishes the relation between APLs and direct input coefficients through Sherman-Morrison *** such a basis,elasticity matrix can be calculated for each element of the APLs matrix,which measures the percentage change in the APLs-matrix element brought by one percentage change in every direct input ***,the percentage change in each APLs-matrix element caused by the real percentage change in each coefficient with other coefficients fixed can be drawn,from which it is easily to find out the APLs-important coefficients and is useful to explain the reason for change in the *** empirical application studies the Chinese ***'s more,the method is applied under different level of *** comparison between the APLs matrix of 1997 and 2002 allows the authors to visualize the elements that change *** the methodology above is applied to explain the change from the perspective of direct input coefficients and find out the important coefficients to the Chinese APLs matrix.

关键词： APLs-important coefficients APLs matrix direct input coefficients elasticity matrix Sherman-Morrison formulation.

Parameter design for a vibration absorber with time-delayed feedback control

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Acta Mechanica Sinica 2019年第3期35卷 624-640页

作者： Feng Wang jian xu School of Aerospace Engineering and Applied Mechanics Tongji UniversityShanghai 200092China

Traditional passive vibration absorbers are effective only when their natural frequencies are close to those of the excitations. To solve this problem, a vibration absorber with time-delayed feedback control is proposed to suppress vibration of the primary system under excitation with changing frequency. Firstly, the mechanical model of the delay coupled system is established. Then, the displacement transfer ratio of the system is obtained. The stability of the system is analyzed since delay may result in destabilization. Next, in order to design the control parameters, the vibration absorption performances of the proposed time-delayed vibration absorber are studied. The vibration absorption region is shown. The results show that time-delayed feedback control is able to change the response of the system. The effective vibration absorption frequency band is adjustable by tuning the control gain and time delay. The effective frequency band can be widened when choosing appropriate control parameters. The vibration absorption performances can be greatly improved by the time-delayed absorber. In addition, the optimum control parameters are obtained. Finally, the experimental prototype is constructed. Several tests with different control parameters are taken. The experimental and analytical results match quite well.

关键词： Vibration absorber Time-delayed feedback control Vibration absorption Experiments Parameter design

Study on tidal gravity observations obtained at stations Zhongshan and Changcheng, Antarctic

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Acta Seismologica Sinica(English Edition) 2001年第3期14卷 325-332页

作者： xu jian-qiao Laboratory of Dynamic Geodesy Institute of Geodesy and Geophysics Chinese Academy of Sciences

Based on the international tidal gravity reference values at station Wuhan, the tidal gravity parameters, including the amplitude factors and phase differences are determined accurately by using the observations with three La-Coste-Romberg (LCR) gravimeters (G-589, ET-20 and ET-21) at stations Zhongshan and Changcheng in the Antarctic, respectively. The standard deviations of the determined amplitude factors of the main tidal waves are better than 0.5%. The amplitude of each tidal wave observed at station Zhongshan is much less than that of the same wave at station Changcheng. The differences of amplitude factors in the diurnal band (O1) at these two stations are less than 7% while those in the semi-diurnal band (M2) are larger than 40%. The influences of meteorology factors, such as atmospheric pressure and temperature, on the tidal gravity observations are very obvious. The oceanic loading effects on the tidal gravity are also very prominent. It is found that the amplitude of the final residual vector of every tidal wave reduces significantly after oceanic correction based on the Schwiderski's global co-tides. However, because the local oceanic loading is not taken into account, the discrepancies of amplitude factors of wave O1 observed at Zhongshan from the corresponding values of theoretical tidal model are about 4%, and 9% at Changcheng.

关键词： stations Zhongshan and Changcheng Antarctic tidal gravity observations international tidal gravity reference values theoretical tidal model P223.9