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Chinese Journal of Structural Chemistry 2013年第12期32卷 1813-1820页

作者： LIU Lei xu xian-Zhu ZHANG Xiao ZHANG Nan-Xi FAN shu-Ge HUANG Yan-Ping State Key Laboratory of Urban Water Resource and Environment & Academy of Fundamental and Interdisciplinary Sciences Harbin Institute of Technology School of Life Science and Technology Harbin Institute of Technology

A supramolecular compound （C6H6NO2）3（C6H5NO2）（PW12O40）·2H2O including the Keggin-type [PW1O40]3- polyanion, [HC6H5NO2]＋（protonated pyridine-4-carboxylic acid molecule）, C6H5NO2 （pyridine-4-carboxylic acid molecule） and two free H20 molecules has been synthesized by the hydrothermal method and characterized by elemental analysis, IR spectra, single-crystal X-ray diffraction and powder X-ray diffraction. The crystal belongs to orthorhombic, space group Pnnm with a = 1.0483（3）, b = 1.4368（6）, c = 2.0526（7） nm, V= 3.0918（18） nm3,Z = 2, F（000） = 3004, Mr= 3406.07, Dc= 1.757 g.m-3,μ = 41.241 mm-1, the final R = 0.0387 and wR = 0.1089 for 2091 observed reflections withI〉 2σ（I）. A total of 30431 reflections were collected, of which 3083 were independent （Rint = 0.0605）. S is 1.182. The title compound presents a 3-D structure via intermolecular hydrogen bonds among [PW12O40]3- polyanions and pyridine-4-carboxylic acid ligands. The ultraviolet and luminescence spectra have been studied at room temperature, of which the purple fluorescent emission is located at 363 nm when excited at 264 nm. Fluorescent emission of the compound derives from the π-π＊ transitions in the pyridine-4-carboxylic acid ligands.

关键词： polyoxometalates hydrothermal synthesis supramolecule crystal structure,luminescent property

ANTI-DIFFUSIVE FINITE DIFFERENCE WENO METHODS FOR SHALLOW WATER WITH TRANSPORT OF POLLUTANT

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Journal of Computational Mathematics 2006年第3期24卷 239-251页

作者： Zhengfu xu Chi-Wang shu Department of Mathematics Pennsylvania State University University Park PA 16802 USA Division of Applied Mathematics Brown University Providence Rhode Island 02912 USA

In this paper we further explore and apply our recent anti-diffusive flux corrected high order finite difference WENO schemes for conservation laws [18] to compute the SaintVenant system of shallow water equations with pollutant propagation, which is described by a transport equation. The motivation is that the high order anti-diffusive WENO scheme for conservation laws produces sharp resolution of contact discontinuities while keeping high order accuracy for the approximation in the smooth region of the solution. The application of the anti-diffusive high order WENO scheme to the Saint-Venant system of shallow water equations with transport of pollutant achieves high resolution

关键词： Anti-diffusive flux correction Sharpening contact discontinuity High order accuracy Finite difference WENO scheme Saint-Venant system of shallow water Transport of pollutant.

A FEASIBLE DIRECTION ALGORITHM WITHOUT LINE SEARCH FOR SOLVING MAX-BISECTION PROBLEMS

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Journal of Computational Mathematics 2005年第6期23卷 619-634页

作者： Feng-min xu Cheng-xian xu Hong-gang xue Department of Mathematics of Faculty of Science Xi'an Jiaotong University Xi'an 710049 China

This paper concerns the solution of the NP-hard max-bisection problems. NCP functions are employed to convert max-bisection problems into continuous nonlinear programming problems. Solving the resulting continuous nonlinear programming problem generates a solution that gives an upper bound on the optimal value of the max-bisection problem. From the solution, the greedy strategy is used to generate a satisfactory approximate solution of the max-bisection problem. A feasible direction method without line searches is proposed to solve the resulting continuous nonlinear programming, and the convergence of the algorithm to KKT point of the resulting problem is proved. Numerical experiments and comparisons on well-known test problems, and on randomly generated test problems show that the proposed method is robust, and very efficient.

关键词： Max-Bisection problem Feasible direction algorithm NCP function Convergence

Short-Time Decoherence of Solid-State Qubit at Optimal Operation Points

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Communications in Theoretical Physics 2005年第5X期44卷 827-832页

作者： ZHAO xu LIANG xian-Ting Department of Physics and Institute of Modern Physics Ningbo University Ningbo 315211 China

We investigate the short-time decoherence of a solid-state qubit under Ohmic noise at optimal operation points. The decoherence is analyzed by maximum norm of the deviation density operator. It is shown that at the temperature T = 3 mK, the loss of the fidelity due to decoherence is much smaller than the DiVincenzo low decoherence criterion, which means that the mode/may be an optimal candidate of qubit for quantum computation.

关键词： short-time decoherence Josephson junction qubit ohmic noise

Photocatalytic divergent decarboxylative amination: a metal-free access to aliphatic amines and hydrazines

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Science China Chemistry 2021年第10期64卷 1756-1762页

作者： xianli shu Ruting xu Saihu Liao Key Laboratory of Molecule Synthesis and Function Discovery(Fujian Province University) State Key Laboratory of Photocatalysis on Energy and EnvironmentCollege of ChemistryFuzhou UniversityFuzhou 350108China Beijing National Laboratory for Molecular Sciences Beijing 100190China

Nitrogen-containing motifs are widely present in natural products, bioactive molecules, and drugs. Accordingly, effective synthetic methods with high efficiency and diversity are highly desirable. Here, we present the invention of a facile, visible lightmediated decarboxylative C(sp^(3))–N bond-forming reaction by employing abundant carboxylic acids as the feedstock and a commercial diazirine as a nitrogen donor. This process is amenable to access both imines and diaziridines, as the corresponding masked amines and hydrazines, through a selectable single or double nitrogen transfer from the diazirine, respectively. This divergent approach works well in both directions with various alkyl carboxylic acids, including primary, secondary, and tertiary acids, as well as natural products and drugs, thus affording a rapid, metal-free approach to build nitrogen-containing molecule libraries with considerable structural diversity, which could thus benefit the related study in context of chemical biology and drug discovery.

关键词： decarboxylative amination divergent synthesis nitrogen transfer amines diazirines

Are Seyfert 2 Galaxies without Polarized Broad Emission Lines More Obscured?

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Chinese Journal of Astronomy and Astrophysics 2008年第2期8卷 204-210页

作者： Xin-Wen shu Jun-xian Wang Peng Jiang Center for Astrophysics University of Science and Technology of China （USTC） Hefei 230026 Joint Institute for Galaxy and Cosmology USTC and Shanghai Astronomical Observatory ChineseAcademy of Sciences Hefei 230026

New XMM-Newton data of seven Seyfert 2 galaxies with optical spectropolarimetric observations are presented. An analysis of the 0.5 - 10 keV spectra shows that four Seyfert 2 galaxies with polarized broad lines （PBLs） are absorbed by NH 〈 1024 cm^-2, while two of three Seyfert 2 galaxies without PBLs show evidence of Compton-thick obscuration, supporting the conclusion that Seyfert 2 galaxies without PBLs are more obscured than those with PBLs, Adding the measured obscuration indicators （NH, T ratio, and Fe Kα line EW） of six luminous AGNs to our previous sample improves the significance level of the difference in absorption from 92.3% to 96.3% for NH, 99.1% to 99.4% for T ratio, and 95.3% to 97.4% for Fe Kα line EW. The present results support and enhance the suggestions that the absence of PBLs in Seyfert 2 galaxies can be explained by larger viewing angles of the line of sight to the putative dusty toms, which leads to the obscuration of the broad-line scattering screen, as expected in the unification model.

关键词： galaxies: active -- galaxies: individual (NGC 513 NGC 1144 NGC 6890 NGC 7682 MCG -3-58-7 F02581-1136 UGC 6100) -- galaxies: Seyfert -- X-rays: galaxies -- polarization

Harmonic Amplification Analysis of Cable Lines with Distributed Parameters Based on Kalman Filter and Convolution Inversion

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Journal of Modern Power Systems and Clean Energy 2023年第6期11卷 1804-1813页

作者： Yang Pu Qin shu Fangwei xu College of Electrical Engineering Sichuan UniversityChengdu 610065China IEEE

Harmonic amplification phenomena could appear at the point of common connection(PCC) of the cable line terminal. However, the distributed parameter model of the cable line contains hyperbolic functions with plural variables, which makes it challenging to obtain the harmonic amplification factor(HAF). Hence, a time-domain method combining the Kalman filter and convolution inversion(KFCI) methods is proposed to address this problem. First, the Kalman filter method optimizes the square wave pulse response(SWPR) with measurement error. Then, the optimized SWPR data are used to get the HAF by the convolution inversion method. Next, the harmonic amplification characteristics of cable lines are explored. Finally, an experimental simulation model is built on the PSCAD software, verifying the optimization effectiveness of Kalman filter for the SWPR with error and the accuracy of the HAF calculated by the proposed method. The analysis rationality of harmonic amplification properties is also demonstrated.

关键词： Cable line distributed parameter Kalman filter convolution inversion harmonic amplification

Decay Rate of Quasilinear Wave Equation with Viscosity

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Acta Mathematicae Applicatae Sinica 2012年第3期28卷 591-596页

作者： Yu-ming QIN Xin LIU shu-xian DENG Department of Applied Mathematics College of SciencesDonghua UniversityShanghai 201620China College of Information Sciences and Technology Donghua UniversityShanghai 201620China

This paper is concerned with the decay rate of solutions for a quasilinear wave equation with viscosity. We use a so-called energy perturbation method to establish decay rate of solutions in terms of energy norm for a class of nonlinear functions. With the help of a comparison lemma of differential inequalities, we establish a relationship between decay rate of solutions and f.

关键词： decay rate energy inequality quasilinear wave equation

Oscillation control for n-dimensional congestion control model via time-varying delay

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Science China(Technological Sciences) 2011年第8期54卷 2044-2053页

作者： ZHANG shu xu Jian School of Aerospace Engineering and Applied Mechanics Tongji University Shanghai 200092 China

Time delay or round trip time (RTT) is an important parameter in the model of Internet congestion control. On the one hand, the delay may induce oscillation via the Hopf bifurcation. In the present paper, a congestion control model of n dimensions is considered to study the delay-induced oscillation. By linear analysis of the n-dimensional system, the critical delay for the Hopf bifurcation is obtained. To describe the relation between the delay and oscillation analytically, the method of multiple scales (MMS) is employed to obtain the bifurcating periodic solution. On the other hand, it can be understood that the oscillation will increase the risk of congestion for the network system. To avoid the congestion derived from the oscillation, a new control scheme is proposed by perturbing the delay periodically. Particularly, according to our study, it is possible to control the oscillation by perturbing only one of the n delays. This provides a practical scheme for the oscillation control in the real network system. By MMS, the strengths of the perturbations are predicted analytically such that the oscillation disappears. To give an example, an eight-dimensional model is studied in detail. The analytical results are in good agreement with the numerical simulations.

关键词： internet congestion control high-dimensional system Hopf bifurcation time-varying delay method of multiple scales

Mass Spectrometric Fragmentation of 1-(Benzyloxycarbonyl)amino-2-alkyl/cycloalkyl Thioacetates:a Thioester Pyrolysis-type Rearrangement under Electron Impact Ionization

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Chinese Chemical Letters 2006年第8期17卷 1069-1072页

作者： shu xu Jia Xi xu Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education College of Chemistry and Molecular Engineering Peking University Beijing 100871

The mass spectrometric fragmentation of 1-（benzyloxycarbonyl）amino-2-alkyl/cycloalkyl thioacetates has been studied with the aid of mass-analysed ion kinetic energy spectrometry under electron impact ionization. All compounds show a tendency to eliminate a ketene, thioacetic acid, and benzyl carbamate molecule, or an acetyl and benzyloxy radicals. A thioester pyrolysis-type rearrangement under electron impact ionizations was observed.

关键词： Electron impact ionization mass spectrometry rearrangement thioacetate.