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Latent ancestral graph of structure vector autoregressive models

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Journal of Systems Engineering and Electronics 2010年第2期21卷 233-238页

作者： Wei Gao1,2and Zheng Tian2,3 1.School of Statistics,Xi’an university of Finance&Economics,Xi’an 710061,p.r.china 2.Department of Applied Mathematics,Northwestern polytechnical university,Xi’an 710072,p.r.china 3.State Key Laboratory of remote Sensing science,institute of remote Sensing Applications,Chinese Academy of sciences,Beijing 100101,p.r.china School of Statistics Xi'an University of Finance & Economics Xi'an 710061 P. R. China Department of Applied Mathematics Northwestern Polytechnical University Xi'an 710072 P. R. China Department of Applied Mathematics Northwestern Polytechnical University Xi'an 710072 P. R. China State Key Laboratory of remote Sensing science Institute of Remote Sensing Applications Chinese Academy of Sciences Beijing 100101 P. R. China

A class of latent ancestral graph for modelling the dependence structure of structural vector autoregressive （VAr） model affected by latent variables is proposed. The graphs are mixed graphs with possibly two kind of edges, namely directed and bidirected edges. The vertex set denotes random variables at dif- ferent times. In Gaussian case, the latent ancestral graph leads to a simple parameterization model. A modified iterative conditional fitting algorithm is presented to obtain maximum likelihood esti- mation of the parameters. Furthermore, a log-likelihood criterion is used to select the most appropriate models. Simulations are performed using illustrative examples and results are provided to demonstrate the validity of the methods.

关键词： multivariate time series latent ancestral graph itera- tive conditional fitting.

On Doubly Degenerate Quasilinear parabolic Equations of Higher Order

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Acta Mathematica Sinica,English Series 2005年第1期21卷 197-208页

作者： Zhen Hai LIU Department of Mathematics,Changsha university of science and technology Changsha 410077,p.r.china Department of Mathematics Changsha University of Science and Technology Changsha 410077 P. R. China

We deal with the existence of periodic solutions for doubly degenerate quasilinear parabolic equations of higher order,which can degenerate,on a part of the boundary,on a segment in the interior of the domain and in t... 详细信息

关键词： Double degeneration Quasilinear parabolic equations periodic solutions

The Synthetic Evaluation of Warhead Overall Efficiency

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Journal of Systems Engineering and Electronics 2003年第1期14卷 12-17页

作者： Gu Xiaohui & Cao Bing College of Mechanics, nanjing university of science & technology, nanjing 210094, p. r. china College of Mechanics Nanjing University of Science & Technology Nanjmg 210094 P. R. China

The evaluation system of smart ammunition warhead overall efficiency has been established in this paper. Allkinds of evaluation methods have been analyzed. Having led the concept of hierarchical structure into technique for orderpreference by similarity to ideal solution (TOpSIS) method, we put forward the step TOpSIS method which is suitable forevaluating the overall efficiency of smart ammunition warheads. In the calculation of index weight, the graded weight cal-culus is put forward which hardly relies on the subjectivity of decision-makers and can reflect the sensitivity and compatibili-ty of the index. In the graded weight calculation, the proportional-arithmetic weight value calculus and sensitivity-compati-bility weight value calculus are given respectively.

关键词： Step analysis TOpSIS method Warhead Efficiency evaluation.

research into a theoretical mode of coherent structures in the wall region of a turbulent boundary layer induced by a wall local disturbance

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progress in Natural science:Materials International 2009年第9期19卷 1119-1124页

作者： Changgen Lua,*, Qinjuan Qi b a College of Atmospheric sciences, nanjing university of Information science & technology, nanjing 210044, china b College of public Management, nanjing university of Information science & technology, nanjing 210044, china College of Atmospheric sciences Nanjing University of Information Science & Technology Nanjing 210044 China College of public Management Nanjing University of Information Science & Technology Nanjing 210044 China

The idea of applying direct numerical simulation (DNS), a theoretical mode of coherent structures in the wall region of a turbulent boundary layer, has been discussed in the literature. The various aspects of the formation mechanism of the coherent structures agree well with both DNS and experimental results. In addition, a close relationship has been found between the evolutional characteristics and factors such as the magnitude and structural distribution of the wall local impulse disturbance, and the amount of energy a local disturbance introduces into the wall region. Moreover, these parameters play key roles in the formation of coherent structures near the wall region of a turbulent boundary layer. Therefore, the wall local impulse disturbance provides a theoretical model for triggering the formation of coherent structures in the wall region of a turbulent boundary layer.

关键词： Turbulent boundary layer Wall region Coherent structure Local disturbance

NEW WAVE-DEpENDENT FOrMULAE FOr SEA SprAY FLUX AT AIr-SEA INTErFACE

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Journal of Hydrodynamics 2009年第4期21卷 573-581页

作者： SHI Jian ZHAO Dong-liang LI Xun-qiang ZHONG Zhong Key Laboratory of Coastal Disaster and Defense Ministry of Education Hohai University Nanjing 210098 China institute of Meteorology PLA University of Science and Technology Nanjing 211101 China College of physical and Environment Oceanography Ocean University of China Qingdao 266100 China

A bubble-derived Sea Spray Generation Function （SSGF） was deduced, which was integrated into the new wave-dependent SSGF. The effect of sea spray feedback was parameterized by the feedback coefficients A and B. The relationship of A（B） and the wind-sea reynolds number was derived, which shows that the feedback effect of sea spray is decreasing with the wave developing. New sea spray flux formulae, including the new SSGF and new feedback coefficients, were proposed, which can reveal clearly the influence of wave state on sea spray fluxes. Spray fluxes in the Humidity Exchange Over the Sea （HEXOS） experiment were simulated again, and results show that spray momentum flux is small in this experiment, but spray heat flux is large. Comparisons of the sea spray fluxes calculated by two kinds of formulae in different wave states show that previous wave-independent spray flux formulae are the special cases of the presented new wave dependent formulae for sea spray flnx.

关键词： sea sray flux HEXOS wave state Sea Spray Generation Function (SSGF)

A new parameterization scheme for sea surface aerodynamic roughness

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progress in Natural science:Materials International 2008年第11期18卷 1365-1373页

作者： Yuping pan~(a,b) Wenyu Sha~c Shouxian Zhu~c Sufang Ge~(a,*) a nanjing university of Information science and technology,nanjing 210044,china b Air Force Meteorological Center of the nanjing Military region,nanjing 210018,china c Meteorology College,The pla university of Information science and technology,nanjing 211101,china nanjing university of Information science and technology Nanjing 210044 China Air Force Meteorological Center of the nanjing Military region Nanjing 210018 China Meteorology College The PLA University of Information Science and Technology Nanjing 211101 China

The dimensionless roughness length derived from dimensional analysis bears a relation to wave age,and the dimensionless form of roughness length can be expressed with the relation with a significant wave *** on six experiments(HEXMAX,rASEX,BIO steady platform,Lake Ontario data analysis FETCH,CBLAST low wind),we verified that the Charnock parameter,Zch,and dimension- less roughness length,z0/Hs,are dependent on wave age,u*/***,we constructed a new scheme for roughness length,and explored its sensitivity to friction velocity and wave *** the newly developed parameterization scheme(pS07)with COArE (Coupled Ocean-Atmosphere response Experiment V.3.0)algorithm,we calculated the data from the North Sea platform experiment in December,1985,and made an attempt to validate the suitability of the pS07 compared to the other three schemes of *** found that the calculated results based on the pS07 are close to the *** also conducted an experiment in which the pS07 was combined with the nested model of waves coupling in datasets of 3 typhoons that occurred at the Zhanjiang *** comparison results between the calculated and observed waves around the Naozhou Island indicate that the new parameterization scheme(pS07)has a good applicability.

关键词： Sea surface roughness parameterization scheme Significant wave height Wave age COArE algorithm

A method of constructing a database-free optimal dynamical system and a global optimal dynamical system

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science china(physics,Mechanics & Astronomy) 2008年第7期51卷 905-915页

作者： WU ChuiJie1? & WANG Liang2 1 State Key Laboratory of Structural Analysis for Industrial Equipment, Dalian university of technology, Dalian 116024, china 2 research Center for Fluid Dynamics, School of science, pla university of science and technology, nanjing 211101, china State Key Laboratory of Structural Analysis for Industrial Equipment Dalian University of Technology Dalian China research Center for Fluid Dynamics School of Science PLA University of Science and Technology Nanjing China

In this paper, to overcome the drawbacks of pOT which minimize the reminder, not only the optimal functional with minimal residual is put forward, but also the method of global optimization is used. Under the condition of large reminder, the optimal bases can also be obtained through the method of pOTres without the approaching of initial conditions. In addition, compared with local optimization, the advantage of global optimization is remarkable. On the one hand, we can expect that the dynamical system based on the global optimal bases will include more information than the ones based on the local optimal bases, since the global optimal bases are much more precise than the local optimal bases. On the other hand, from the point of view of error, the global optimal bases are independent of the choice of the object functional and the initial bases.

关键词： dynamical system residual global optimization

Syntheses of amphiphilic biodegradable copolymers of poly(ethyl ethylene phosphate) and poly(3-hydroxybutyrate) for drug delivery

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science china Chemistry 2009年第7期52卷 961-968页

作者： CHENG Jing1 & WANG Jun2 1 Department of polymer science and Engineering, university of science and technology of china, Hefei 230026, china 2 Hefei National Laboratory for physical sciences at Microscale, School of Life sciences, university of science and technology of china, Hefei 230027, china Department of polymer science and Engineering University of Science and Technology of China Hefei China Hefei National Laboratory for physical sciences at Microscale School of Life Sciences University of Science and Technology of China Hefei China

Biodegradable and amphiphilic triblock copolymers poly(ethyl ethylene phosphate)-poly(3-hydroxybutyrate)-poly(ethyl ethylene phosphate) (pEEp-b-pHB-b-pEEp) have been successfully synthesized through ring-opening polymerization. The structures are confirmed by gel permeation chromatography and NMr analyses. Crystallization investigated by X-ray diffraction reveals that the block copolymer with higher content of poly(ethyl ethylene phosphate) (pEEp) is more amorphous, showing decreased crystallizability. The obtained copolymers self-assemble into biodegradable nanoparticles with a coreshell micellar structure in aqueous solution, verified by the probe-based fluorescence measurements and transmission electronic microscopy (TEM) observation. The hydrophobic poly(3-hydroxybutyrate) (pHB) block serves as the core of the micelles and the micelles are stabilized by the hydrophilic pEEp block. The size and size distribution are related to the compositions of the copolymers. paclitaxel (pTX) has been encapsulated into the micelles as a model drug and a sustained drug release from the micelles is observed. MTT assay also demonstrates that the block copolymers are biocompatible, rendering these copolymers attractive for drug delivery.

关键词： poly(3-hydroxybutyrate) polyphosphoester drug delivery polymeric nanoparticles

TWO-GrID METHOD FOr CHArACTErISTICS FINITE-ELEMENT SOLUTION OF 2D NONLINEAr CONVECTION-DOMINATED DIFFUSION prOBLEM

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Applied Mathematics and Mechanics(English Edition) 2005年第11期26卷 1506-1514页

作者：秦新强School of sciences Xi’an Jiaotong university Xi’an 710049 p.r.china School of sciences Xi’an university of technology Xi’an 710048 p.r.china) 马逸尘章胤 School of sciences Xi’an Jiaotong UniversityXi’an 710049 P.R.China School of sciences Xi’an University of TechnologyXi’an 710048 P.R.China

For two-dimension nonlinear convection diffusion equation, a two-grid method of characteristics finite-element solution was constructed. In this method the nonlinear iterations is only to execute on the coarse grid and the fine-grid solution can be obtained in a single linear step. For the nonlinear convection-dominated diffusion equation, this method can not only stabilize the numerical oscillation but also accelerate the convergence and improve the computational efficiency. The error analysis demonstrates if the mesh sizes between coarse-grid and fine-grid satisfy the certain relationship, the two-grid solution and the characteristics finite-element solution have the same order of accuracy. The numerical is more efficient than that of characteristics example confirms that the two-grid method finite-element method.

关键词： convection-diffusion equation characteristics finite-element two-grid method convergence