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Science China Chemistry 2006年第5期49卷 437-444页

作者： WANG Jingping LI jie niu Jingyang Institute of Molecular and Crystal Engineering Institute of Chemistry and Chemical Engineering Henan University Kaifeng 475001 China Institute of Molecular and Crystal Engineering Institute of Chemistry and Chemical Engineering Henan University Kaifeng 475001 China Institute of Molecular and Crystal Engineering Institute of Chemistry and Chemical Engineering Henan University Kaifeng 475001 China

A two-dimensional network compound [Ce(DMF)4(H2O)][α-BW12O40]·H2O·(HDMA)2 (HDMA = protoned dimethylamine, DMF = N,N-dimethylformamide) was synthesized from α-H5BW12O40·nH2O, Ce(NO3)3·6H2O and DMF and characterized by IR, UV spectra and TG-DTA. The result of the X-ray single crystal diffraction indicates that the crystal is monoclinic, space group P21/n, with unit cell dimensional: a = 1.1983(3), b = 2.4216(5), c = 1.9517(4) nm, β = 92.91(3)°, Z = 4, R1 = 0.07710, wR2 = 0.1416. Structural analysis indicates that every [Ce(DMF)4(H2O)]3+ building block is surrounded by three adjacent [α-BW12O40]5- polyanions, meanwhile, every [α-BW12O40]5- polyanion interconnects with three neighboring [Ce(DMF)4(H2O)]3+ subunits, by making use of which two-dimensional network structure can be constructed. The result of thermogravimetric analysis manifests that the title compound has two-stage weight loss and the decomposition temperature of the title polyanionic framework is 560℃ . The electrochemical analysis shows the title polyanion has three-step redox processes in the pH = 4―7 media.

关键词： borotungstic acid, network structure, polyoxometalates, crytal structure.

Damage identification method of girder bridges based on finite element model updating and modal strain energy

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Science China(Technological Sciences) 2015年第4期58卷 701-711页

作者： niu jie ZONG Zhou Hong CHU Fu Peng School of Civil Engineering Southeast University Vibration Engineering Section College of Engineering Mathematics and Physical Sciences University of Exeter Fujian Academy of Building Research

A timely and accurate damage identification for bridge structures is essential to prevent sudden failures/collapses and other catastrophic *** on response surface model(RSM)updating and element modal strain energy(EMSE)damage index,this paper proposes a novel damage identification method for girder bridge *** effectiveness of the proposed damage identification method is investigated using experiments on four simply supported steel *** Xiabaishi Bridge,a prestressed continuous rigid frame bridge with large span,as the engineering background,the proposed damage identification method is validated by using numerical simulation to generate different bearing damage ***,the efficiency of the method is justified by considering its application to identifying cracking damage for a real continuous beam bridge called Xinyihe *** is concluded that the EMSE damage index is sensitive to the cracking damage and the bearing *** locations and levels of multiple cracking damages and bearing damages can be also *** results illuminate a great potential of the proposed method in identifying damages of real bridge structures.

关键词： damage identification response surface model finite element model updating element modal strain energy damage index girder bridge

Improved HHT and its application in narrowband radar imaging for precession cone-shaped targets

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Journal of Systems Engineering and Electronics 2014年第6期25卷 977-986页

作者： Shen Zhao jie niu Xiang Li Chunjie Qiao College of Mechatronics and Automation National University of Defense Technology Department of Missile Engineering Ordnance Engineering College College of Electronic Science and Engineering National University of Defense Technology

Imaging the spatial precession cone-shaped targets with narrowband radar is a new technical approach in mid-course recognition problem. However, most existing time-frequency methods still have some inevitable deficiencies for extracting microDoppler information in practical applications, which leads to blurring of the image. A new narrowband radar imaging algorithm for the precession cone-shaped targets is proposed. The instantaneous frequency of each scattering point is gained by using the improved Hilbert-Huang transform, then the positions of scattering points in the parameter domain are reconstructed. Numerical simulation and experiment results confirm the effectiveness and high precision of the proposed algorithm.

关键词： improved Hilbert-Huang transform(HHT) instanta-neous frequency narrowband radar imaging precession cone-shaped targets

CF_4 decomposition without water over a solid ternary mixture consisting of NaF,silicon and one metal oxide

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Journal of Natural Gas Chemistry 2011年第5期20卷 543-546页

作者： Xiufeng Xu Xianjun niu jie Fan Yanan Wang Ming Feng School of Chemistry and Biology Yantai University Yantai 264005 Shandong China

A solid ternary mixture consisting of NaF, silicon and one of the metal oxides such as Al2O3, MgO, CaO, SrO, BaO was prepared and used as a defluorinated reagent for CF4 decomposition. The results show that the initial conversion of CF4 reached 100% over NaF-Si-MgO and NaF-Si-CaO at 850°C, and the reagent with NaF/Si/MgO molar ratio of 33/34/33 exhibited a high reactivity with a full conversion of CF4 lasting for 57 min. The plausible paths of CF4 decomposition over NaF-Si-Al2O3, NaF-Si-MgO, NaF-Si-CaO, NaF-Si-SrO and NaF-Si-BaO are proposed.

关键词： CF4 decomposition without water solid ternary mixture defluorinated reagent reactivity

Finite element model validation of bridge based on structural health monitoring——Part I: Response surface-based finite element model updating

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Journal of Traffic and Transportation Engineering(English Edition) 2015年第4期2卷 258-278页

作者： Zhouhong Zong Xiaosong Lin jie niu School of Civil Engineering Southeast University School of Civil Engineering Fujian University of Technology

In the engineering practice, merging statistical analysis into structural evaluation and assessment is a tendency in the future. As a combination of mathematical and statistical techniques, response surface （RS） methodology has been successfully applied to design optimization, response prediction and model validation. With the aid of RS methodology, these two serial papers present a finite element （FE） model updating and validation method for bridge structures based on structural health monitoring. The key issues to implement such a model updating are discussed in this paper, such as design of experiment, parameter screening, construction of high-order polynomial response surface model, optimization methods and precision inspection of RS model. The proposed procedure is illustrated by a prestressed concrete continuous rigid-frame bridge monitored under operational conditions. The results from the updated FE model have been compared with those obtained from online health monitoring system. The real application to a full-size bridge has demonstrated that the FE model updating process is efficient and convenient. The updated FE model can relatively reflect the actual condition of Xiabaishi Bridge in the design space of parameters and can be further applied to FE model validation and damage identification.

关键词： Response surface methodologyFinite element model updatingStructural health monitoringParameter screeningFinite element model validationContinuous rigid frame bridgemodel

Finite element model validation of bridge based on structural health monitoring——Part Ⅱ:Uncertainty propagation and model validation

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Journal of Traffic and Transportation Engineering(English Edition) 2015年第4期2卷 279-289页

作者： Xiaosong Lin Zhouhong Zong jie niu aSchool of Civil Engineering Fujian University of Technology School of Civil Engineering Southeast University

Because of uncertainties involved in modeling, construction, and measurement systems, the assessment of the FE model validation must be conducted based on stochastic mea- surements to provide designers with confidence for further applications. In this study, based on the updated model using response surface methodology, a practical model vali- dation methodology via uncertainty propagation is presented. Several criteria of testing/ analysis correlation are introduced, and the sources of model and testing uncertainties are also discussed. After that, Monte Carlo stochastic finite element （FE） method is employed to perform the uncertainty quantification and propagation. The proposed methodology is illustrated with the examination of the validity of a large-span prestressed concrete continuous rigid frame bridge monitored under operational conditions. It can be concluded that the calculated frequencies and vibration modes of the updated FE model of Xiabaishi Bridge are consistent with the measured ones. The relative errors of each frequency are all less than 3.7%. Meanwhile, the overlap ratio indexes of each frequency are all more than 75%; The MAC values of each calculated vibration frequency are all more than 90%. The model of Xiabaishi Bridge is valid in the whole operation space including experimental design space, and its confidence level is upper than 95%. The validated FE model of Xia- baishi Bridge can reflect the current condition of Xiabaishi Bridge, and also can be used as basis of bridge health monitoring, damage identification and safety assessment.

关键词： Bridge engineeringModel validationCorrelation of testing/analysisUncertainty quantification andpropagationEvaluation of model precision

A new method of micro-motion parameters estimation based on cyclic autocorrelation function

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Science China(Information Sciences) 2013年第10期56卷 21-31页

作者： niu jie LI KangLe JIANG WeiDong LI Xiang KUANG GangYao ZHU HongYu Institute of Space Electronics Information Technology National University of Defense Technology Jiangnan Institute of Computing Technology

Signals with sinusoidal frequency modulation(FM)are the general form of micro-Doppler signals in radar echoes from targets with *** paper derives the cyclic autocorrelation function of a sinusoidal FM signal using its cyclostationary characteristics,and estimates the parameters of amplitude,modulation index,micro-motion period and noise power based on cyclic autocorrelation *** estimation method is robust in noise environment when compared with conventional time-frequency analysis ***,the performances of estimation by utilizing the simulation data and darkroom measurement are shown in *** Monte-Carlo simulation results show that the estimator is asymptotically optimal at SNR above6 dB.

关键词： micro-motion cyclic autocorrelation function sinusoidal frequency modulation signal parameter estimation

Hybrid Tungstocuprate [Cu(2,2′-bpy)_3]_2H_4[CuW_(12)O_(40)]·6H_2O Based on Keggin Polyoxoanion [CuW_(12)O_(40)]^(6-) with Cu~Ⅱas Heteroatom

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Chemical Research in Chinese Universities 2007年第3期23卷 263-267页

作者： WANG Jing-ping MA Peng-tao LI jie niu Jing-yang Institute of Molecular and Crystal Engineering School of Chemistry and Chemical Engineering Henan University Kaifeng 475001 P. R. China

A novel hybrid tungstocuprate （ Ⅱ ） [ Cu （2,2＇-bpy） 3 ] 2 H4 [ CuW12O40 ] · 6H2O （ 2,2＇-bpy = 2,2＇-bipyfidine） was synthesized via hydrothermal method and characterized using elemental analyses, IR, UV, XPS, TG-DSC, EPR, and X-ray single crystal diffraction. The structural analysis shows that the complex consists of an unusual Keggin-type polyoxoanion [ CuW12O40 ]^6- and a pair of chiral complex cations [ Cu（2,2＇-bpy） 3 ]^＋ together with four protons and six crystallization water molecules, and the Keggin polyoxoanion is connected with [ Cu （2,2＇-bpy）3 ]^＋v/a multiple C-H…O hydrogen bonds resulting in a dimer.

关键词： Hydrothermal synthesis Polyoxometalates Keggin Tungstocuprate

■-dressing Method for the Coupled Two-component Kundu-Eckhaus Equations

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Acta Mathematicae Applicatae Sinica 2024年

作者： Zhen-jie niu Biao LI School of Mathematics and Statistics Ningbo University

In this paper,■-dressing method based on a local 3×3 matrix ■-problem with non-normalization boundary conditions is used to investigate coupled two-component Kundu-Eckhaus ***,we propose a new compatible system with singular dispersion relation,that is time spectral problem and spatial spectral problem of coupled two-component Kundu-Eckhaus equations via constraint ***,we derive a hierarchy of nonlinear evolution equations by introducing a recursive *** last,by solving constraint matrixes,a spectral transform matrix is given which is sufficiently important for finding soliton solutions of potential function,and we obtain N-soliton solutions of coupled two-component Kundu-Eckhaus equations.

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Digital simulation of 3D turbulence wind field of Sutong Bridge based on measured wind spectra

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2012年第2期13卷 91-104页

作者： Hao WANG Zhou-hong ZONG Ai-qun LI Teng TONG jie niu Wen-ping DENG Key Laboratory of Concrete and Prestressed Concrete Structures of Ministry of Education Southeast UniversityNanjing 210096China Key Laboratory of Environmental Impact and Structural Safety in Engineering China University of Mining&TechnologyXuzhou 221116China

Time domain analysis is an essential implement to study the buffeting behavior of long-span bridges for it can consider the non-linear effect which is significant in long-span bridges. The prerequisite of time domain analysis is the accurate description of 3D turbulence winds. In this paper, some hypotheses for simplifying the 3D turbulence simulation of long-span cable-stayed bridges are conducted, considering the structural characteristics. The turbulence wind which is a 3D multivariate stochastic vector process is converted into four independent 1D univariate stochastic processes. Based on recorded wind data from structural health monitoring system (SHMS) of the Sutong Bridge, China, the measured spectra expressions are then presented using the nonlinear least-squares fitting method. Turbulence winds at the Sutong Bridge site are simulated based on the spectral representation method and the Fast Fourier transform (FFT) technique, and the relevant results derived from target spectra including measured spectra and recommended spectra are compared. The reliability and accuracy of the presented turbulence simulation method are validated through comparisons between simulated and target spectra (measured and recommended spectra). The obtained turbulence si-mulations can not only serve further analysis of the buffeting behavior of the Sutong Bridge, but references for structural anti-wind design in adjacent regions.

关键词： Turbulence simulation Spectral representation method Fast Fourier transform (FFT) Cable-stayed bridges Struc-tural health monitoring system (SHMS) Power spectral density