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A Generalized Vector-valued Variational Principle in Fréchet Spaces

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Acta Mathematica Sinica,English Series 2010年第11期26卷 2145-2156页

作者： Jing Hui qiu xin Qing YANG Department of Mathematics Suzhou University Suzhou 215006 P. R. China

In the framework of Frechet spaces, we give a generalized vector-valued Ekeland＇s variational principle, where the perturbation involves the subadditive functions of countable generating semi-norms. By modifying and developing the method of Cammaroto and Chinni, we obtain a density theorem on extremal points of the vector-valued variational principle, which extends and improves the related known results.

关键词： Locally convex space Fr^chet space vector-valued variational principle extremal point density

New Positive and Negative Hierarchies of Integrable Differential-Difference Equations and Conservation Laws

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Communications in Theoretical Physics 2009年第1期51卷 17-22页

作者： LI xin-Yue ZHAO qiu-Lan College of Science Shandong University of Science and Technology Qingdao 266510 China

Two hierarchies of nonlinear integrable positive and negative lattice equations are derived from a discrete spectrak problem. The two lattice hierarchies are proved to have discrete zero curvature representations associated with a discrete spectral problem, which also shows that the positive and negative hierarchies correspond to positive and negative power expansions of Lax operators with respect to the spectral parameter, respectively. Moreover, the integrable lattice models in the positive hierarchy are of polynomial type, and the integrable lattice models in the negative hierarchy are of rational type. Further, we construct infinite conservation laws about the positive hierarchy.

关键词： discrete zero curvature equations Liouville integrability discrete Hamiltonian structure conservation laws

Testing Lorentz violation using propagating UHECRs

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Chinese Journal of Astronomy and Astrophysics 2009年第4期9卷 409-421页

作者： Cong-xin qiu Zi-Gao Dai Department of Astronomy Nanjing University Nanjing 210093 China

Lorentz invariant violation （LIV） test is important for studying modem physics. All the known astrophysical constraints either have a very small examinable parameter space or are only suitable for some special theoretical models. Here, we suggest that it is possible to directly detect the time-delay of ultra-high-energy cosmic-rays （UHECRs）. We discuss some difficulties in our method, including the intergalactic magnetic fields. It seems that none of them are crucial, hence this method could give a larger examinable parameter space and a stronger constraint on LIV.

关键词： cosmic rays-gamma rays bursts-ISM magnetic fields-relativity

Magneto-Optic Fiber Gratings Useful for Dynamic Dispersion Management and Tunable Comb Filtering

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Chinese Physics Letters 2010年第6期27卷 225-228页

作者： WU Bao-Jian LU xin qiu Kun Key Lab of Broadband Optical Fiber Transmission and Communication Networks of the Ministry of Education University of Electronic Science and Technology of China Chengdu 611 731

Intelligent control of dispersion management and tunable comb filtering in optical network appfications can be performed by using magneto-optic fiber Bragg gratings （MFBGs）. When a nonuniform magnetic field is applied to the MFBG with a constant grating period, the resulting grating response is equivalent to that of a conventional chirped grating. Under a linearly nonuniform magnetic field along the grating, a linear dispersion is achieved in the grating bandgap and the maximal dispersion slope can come to 1260ps/nm2 for a l0-mm-long fiber grating at 1550nm window. Similarly, a Gaussian-apodizing sarnpled MFBG is also useful for magnetically tunable comb filtering, with potential application to clock recovery from return-to-zero optical signals and optical carrier tracking.

关键词： MAGNETOOPTICS BRAGG gratings DISPERSION COMB filters OPTICAL communications MAGNETIC fields GAUSSIAN processes SIGNAL processing

A compact streamfunction-velocity scheme for the 2-D unsteady incompressible Navier-Stokes equations in arbitrary curvilinear coordinates

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Journal of Hydrodynamics 2019年第4期31卷 827-839页

作者： Jian-xin qiu Bo Peng Zhen-fu Tian Department of Mechanics and Engineering Science Fudan University Shanghai 200433 China

A streamfunction-velocity formulation-based compact difference method is suggested for solving the unsteady incompressible Navier-Stokes equations in the arbitrary curvilinear coordinates, in which the stream function and its first derivatives as the unknown variables are utilized. Numerical examples, involving the boundary layer problem, a constricted channel flow, driven polar cavity flow and trapezoidal cavity flow problem, are solved by the present method. Numerical results demonstrate the accuracy of the proposed scheme and exhibit the numerical capability to simulate the flow problems on geometries beyond rectangular. For driven polar cavity flow problem, the results show that the flow for Re = 5 000 is not steady but time-periodic, and the critical Reynold number (Rec) for the occurrence of a Hopf bifurcation is given.

关键词： Streamfunction-velocity formulation arbitrary curvilinear coordinates compact scheme unsteady incompressible flow

Molecular Dynamics Simulations of Atomistic Hydration Structures of Poly(vinyl methyl ether)

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Chinese Journal of Polymer Science 2016年第11期34卷 1396-1410页

作者：吴荣亮 xin-long qiu Xiao-zhen Yang College of Material Science and Engineering State Key Laboratory for Modification of Chemical Fibers and Polymer Materials Donghua University Shanghai 201620 China Beijing National Laboratory for Molecular Sciences State Key Laboratory of Polymer Science and Engineering Joint Laboratory of Polymer Science and Materials Institute of Chemistry Chinese Academy of Sciences Beijing 100190 China

Molecular dynamics simulations have been performed on the aqueous solutions of poly（vinyl methyl ether）（PVME） at various concentrations. Both radial and spatial distribution functions are used to investigate the detailed hydration structures. The structures of water are found to get increasingly concentrated when polymers are introduced and the water motions are severely hindered by the polymer matrix. At low concentrations, larger populations of tt conformers in meso dyads than those at higher concentrationsare found and this phenomenon is believed to be due to the increasing in bonding of water molecule to two ether oxygens in meso dyad. At higher concentrations, the size and conformations of polymers are quite similar to those in bulk. A transition of hydrogen bond fractions between PVME and water at around the concentration of 0.3 is observed and this value is perfectly in agreement with the results of conformational analysis and Raman spectra. Second neighbor hydrogen bond statistics revealed the domination of complicated hydrogen bond networks at low concentrations, but single hydrogen bonds as well as isolated clusters composed of 2-4 water molecules are usual around each polymer repeat unit.

关键词： vinyl conformational chains bonding perfectly backbone hydration hydrophilic bonds hydrophobic

Novel insights into the mechanisms whereby isoflavones protect against fatty liver disease

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World Journal of Gastroenterology 2015年第4期21卷 1099-1107页

作者： Long-xin qiu Tong Chen School of Life Sciences Longyan University Key Laboratory of Preventive Veterinary Medicine and Biotechnology of Fujian Province

Fatty liver disease(FLD) is a growing public health problem worldwide. There is an urgent requirement for alternative and natural medicine to treat this disease. As phytochemicals, isoflavones have attracted considerable attention for the prevention of FLD. Numerous studies have revealed that isoflavones protect against FLD through various pathways which modulate fatty acid β-oxidation, lipid synthesis, and oxidative stress. Recently, the aldose reductase(AR)/polyol pathwayhas been reported to be involved in the development of FLD by modulating hepatic fructose production, peroxisome proliferator-activated receptor(PPAR)α activity, cytochrome P450(CYP)2E1 expression, and gut bacterial endotoxin-induced cytokine release. It has been reported that some isoflavones are potent AR inhibitors. Here, we review the anti-FLD actions of isoflavones and the proposed mechanism whereby isoflavones protect against FLD, with regard to the AR/polyol pathway. We propose that isoflavones block the AR/polyol pathway and in turn reduce fructose production and subsequent fat accumulation in the liver in diabetic or high-glucose-diet mice. In addition, in rodents with alcoholic liver disease or nonalcoholic fatty liver disease/nonalcoholic steatohepatitis, inhibition of AR by isoflavones may improve PPARα-mediated fatty acid oxidation, reduce hepatic steatosis, and attenuate CYP2E1-mediated oxidative stress or AR/gut bacterial endotoxin-mediated cytokine overproduction, to alleviate progression of FLD.

关键词： Isoflavones Fatty liver disease Aldose reductase F

Investment in deepwater oil and gas exploration projects:a multi-factor analysis with a real options model

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Petroleum Science 2015年第3期12卷 525-533页

作者： xin-Hua qiu Zhen Wang Qing Xue School of Business Administration China University of Petroleum Academy of Chinese Energy Strategy China University of Petroleum

Deepwater oil and gas projects embody high risks from geology and engineering aspects, which exert substantial influence on project valuation. But the uncer- tainties may be converted to additional value to the projects in the case of flexible management. Given the flexibility of project management, this paper extends the classical real options model to a multi-factor model which contains oil price, geology, and engineering uncertainties. It then gives an application example of the new model to evaluate deepwater oil and gas projects with a numerical analytical method. Compared with other methods and models, this multi-factor real options model contains more project information. It reflects the potential value deriving not only from oil price variation but also from geology and engi- neering uncertainties, which provides more accurate and reliable valuation information for decision makers.

关键词： Investment decision - Real options Multi-factor model Option pricing - Deepwater oil and gas

Elliptical Galaxies with Emission Lines from the Sloan Digital Sky Survey

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Chinese Journal of Astronomy and Astrophysics 2006年第1期6卷 15-24页

作者： Ying-He Zhao qiu-Sheng Gu Zhi-xin Peng Lei Shi xin-Lian Luo qiu-He Peng Department of Astronomy Nanjing University Nanjing 210093

As part of a study of star formation history along the Hubble sequence, we present here the results for 11 elliptical galaxies with strong nebular emission lines. After removing the dilution from the underlying old stellar populations by use of stellar population synthesis model, we derive the accurate fluxes of all the emission lines in these objects, which are then classified, using emission line ratios, into one Seyfert 2, six LINERs and four HII galaxies. We also identify one HII galaxy （A1216＋04） as a hitherto unknown Wolf-Rayet galaxy from the presence of the WolfRayet broad bump at 4650A. We propose that the star-forming activities in elliptical galaxies are triggered by either galaxy-galaxy interaction or the merging of a small satellite/a massive star cluster, as has been suggested by recent numerical simulations.

关键词： Galaxies: elliptical and lenticular cD Galaxies: starburst - Galaxies:individual: A1212+06 A1216+04 CGCG13-83 IC 225