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Search Results: 1 - 10 of 25689 matches for " Yongquan Dong "
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Nonexchangeable Degrees of Best-Possible Bounds for Copulas Specified at a Single Interior Point

DONG Yongquan,

系统科学与数学 , 2008,
Abstract: The degrees of nonexchangeability about the best bounds of Copulas being specified at a single interior point are studied to construct four maximally nonexchangeable Copulas whose features and properties are studied as whell. Moreover this paper define non-radially and non-jointly symmetry about random variables and Copulas, and show that for the four Copulas the three nonexchangeable measures are equivelent. On the other hand, using $L_P$ distance theory we calculate another nonexchangeable degree formulate whose normal coefficient is k_p=3^{p+1}(p+1){{p+2} \over 4}, in particular, the formulate with k_1={27 \over 2} or k_2=81 may be commonly used.
A Novel Method for Extracting Information from Web Pages with Multiple Presentation Templates
Qingzhong Li,Yanhui Ding,An Feng,Yongquan Dong
Journal of Software , 2010, DOI: 10.4304/jsw.5.5.506-513
Abstract: Web information extraction is the key part of web data integration. With the need of e-commerce website and the development of web design, web pages with multiple presentation templates arise. The current web information extraction systems are usually based on single presentation template, so web pages with multiple presentation templates can’t be extracted efficiently. This paper focuses on the extraction problem about web pages with multiple presentation templates. Four different kinds of this problem have been considered, and a novel method based on path entropy, presentation regularity and ontology knowledge is presented. The experiment indicates that this method is very promising and it achieves excellent recall and precision.
The Application of Decellularized Matrices in the Tissue Engineering of Vascular Graft
Jiande DONG,Jian ZHANG,Yongquan GU
Chinese Journal of Lung Cancer , 2009,
Dynamics of a Delay-Varying Computer Virus Propagation Model
Jianguo Ren,Yonghong Xu,Yongchang Zhang,Yongquan Dong,Guosheng Hao
Discrete Dynamics in Nature and Society , 2012, DOI: 10.1155/2012/371792
Abstract: By considering the varying latency period of computer virus, we propose a novel model for computer virus propagation in network. Under this model, we give the threshold value determining whether or not the virus finally dies out, and study the local stability of the virus-free and virus equilibrium. It is found that the model may undergo a Hopf bifurcation. Next, we use different methods to prove the global asymptotic stability of the equilibria: the virus-free equilibrium by using the direct Lyapunov method and virus equilibrium by using a geometric approach. Finally, some numerical examples are given to support our conclusions.
Determination of the Volatile Composition in Essential Oil of Descurainia sophia (L.) Webb ex Prantl (Flixweed) by Gas Chromatography/Mass Spectrometry (GC/MS)
Jing Li,Xingang Liu,Fengshou Dong,Jun Xu,Yongquan Zheng,Weili Shan
Molecules , 2010, DOI: 10.3390/molecules15010233
Abstract: Exhaustive hydro-distillation of Descurainia sophia (L.) Webb ex Prantl (flixweed) collected from two different locations (Cangzhou city-Sample 1 and Beijing city-Sample 2) gave in both cases yellowish colored oils in 0.31 and 0.26% yield, respectively. Detailed chemical composition of the essential oils was analyzed by GC and GC/MS, and forty and thirty-eight compounds were identified. The results indicated that the most abundant component of Sample 1were cis-β-ocimene (20.1%), menthol (11.27%), neoisomenthyl acetate (3.5%), alloaromadendrene (2.28%) and longicyclene (2.25%). Compared with the constituents of Sample 1, several chemical compounds such as 1,8-cineole, α-eudesmol, cis, trans-farnesol and β-pinene were not detected in Sample 2 although it was similarly dominated by cis-β-ocimene (17.12%), menthol (10.7%) and neoisomenthyl acetate (2.96%). Final analysis of the chemical constituents in the essential oils of the two samples showed similarity in their chemical composition, but the relative content of all shared chemical constituents in Sample 2 was lower than that in Sample 1.
Normes invariantes et existence de filtrations admissibles
Yongquan Hu
Mathematics , 2007,
Abstract: Let L be a finite extension of Q_p and d a positive integer. A conjecture, due to C. Breuil and P. Schneider, says that the existence of invariant norms on certain locally algebraic representations of GL_{d+1}(L) should be equivalent to the existence of certain (d+1)-dimensional de Rham representations of Gal(\bar{L}/L). We prove the easy direction of this conjecture: the existence of invariant norms implies the existence of admissible filtrations, by generalizing an idea of M.Emerton.
Sur quelques représentations supersingulières de $GL_2(Q_{p^f})$
Yongquan Hu
Mathematics , 2009,
Abstract: Let p>3 be a prime, f a positive integer and Q_{p^f} the unramified extension of Q_p of degree f. After Breuil and Paskunas, to a generic semi-simple continue modulo p representation of the absolute Galois group of Q_{p^f}, we can associate a parameterized family of smooth admissible modulo p representations of GL_2(Q_{p^f}). In this article, we prove that there are more parameters than those known.
Diagrammes canoniques et representations modulo $p$ de $\GL_2(F)$
Yongquan Hu
Mathematics , 2009,
Abstract: Let $p$ be a prime number and $F$ a local field with residual characteristic $p$. In this article, to an irreducible smooth representation of $GL_2(F)$ over $\bar{\mathbf{F}}_p$ with central character, we associate canonically a diagram which determines the original representation up to isomorphism. We also determine it in some cases.

Dong Zhiyong,Wu Chigong,Yang Yongquan,Zhang Yun,

力学学报 , 1995,
Abstract: This paper investigates behaviour of air ent rained by rollers at the point ofnon-aerated plunging jet entry. Experimental results indicate that air retained from thepoint of jet entry diffuses along shear layer.Air concentration at the point of entry increocseswith water depth decreasing.There is a form of error function for velocity distribution ofair-water mixture in shear laver. Air concentration is correspondent to normal distribution,in internal and external shear layers respectively. The agreement between the theoreticalequations and the experimental results is good.In addition,the thickness of air-water mixinglayer and air flow rate near the point of jet entry are given theoretically.
Preparation and flocculation performance of a polyacrylamide/montmorilonite hybrid flocculant

DONG Yongquan,DENG Anmin,GUO Huabing,TANG Xinghua,

环境科学学报 , 2009,
Abstract: Organophilic-montmorillonite (O-MMT) was prepared by a eation exchange reaction between inorganic ions of montmorillonite and annmonium cations of cetyl trimethyl ammonium bromide ( CTAB ). Montmorilonite/polyacrylamide ( MMT/PAM ) hybrid was then prepared via intercalation polymerization of acrylamide among the lamellae of O-MMT initiated by cerium ammonium nitrate, ( NH_4 )_2Ce( NO_3 )_6. The effects of initiator dosage, polymerization time and MMT content on the intrinsic viscosity of the MMT/PAM hybrid were investigated. The structures of Na-MMT,O-MMT and MMT/ PAM hybrid were characterized by means of X-ray diffraction ( XRD) ., FTIR, transmission electron microscopy (TEM) , and the flocculating effects of MMT/PAM hybrid and pure PAM on chromium trioxide suspension were compared. The results showed that nano-sized MMT was dispersed evenly in the polyaciylamide matrix, and the flocculating effect of MMT/PAM hybrid was better than that of pure PAM for 0. 5% chromium trioxide suspension when the MMT content was kept at 0.5%~5.0%.
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