OALib Journal期刊

ISSN: 2333-9721




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匹配条件: “Zhou Xuan” ,找到相关结果约35029条。
Feature Selection for Image Classification Based on a New Ranking Criterion  [PDF]
Xuan Zhou, Jiajun Wang
Journal of Computer and Communications (JCC) , 2015, DOI: 10.4236/jcc.2015.33013

In this paper, a feature selection method combining the reliefF and SVM-RFE algorithm is proposed. This algorithm integrates the weight vector from the reliefF into SVM-RFE method. In this method, the reliefF filters out many noisy features in the first stage. Then the new ranking criterion based on SVM-RFE method is applied to obtain the final feature subset. The SVM classifier is used to evaluate the final image classification accuracy. Experimental results show that our proposed relief- SVM-RFE algorithm can achieve significant improvements for feature selection in image classification.

Defect Core Structures in Twisted Nematic and Twisted Chiral Liquid Crystals  [PDF]
Xuan Zhou, Guili Zheng, Zhidong Zhang
Journal of Modern Physics (JMP) , 2013, DOI: 10.4236/jmp.2013.42037

The defect structures of s = ±1/2 twist disclinations in twisted nematic and twisted chiral liquid crystals have been investigated within the Landau-de Gennes theory numerically. Our results show that there exists eigenvalue exchange across the defect core of both the two models. The defect core is essentially biaxial and never isotropic. The defect centre is uniaxial and is surrounded by a strong biaxial region.

In Vitro Immersion Behavior of Cold Sprayed Hydroxyapatite/Titanium Composite Coatings  [PDF]
Lin Lu, Xuan Zhou, P. Mohanty
Journal of Biosciences and Medicines (JBM) , 2014, DOI: 10.4236/jbm.2014.22002

In previous study, dense and homogenous 20wt% HAP/Ti composite coatings were successfully deposited on Ti substrates by cold gas dynamic spray technique. The results revealed that the phase composition of the HAP in the deposit is identical to that of the precursor powder and the bonding strength of the deposit is comparable/better to that of the plasma sprayed HAP. A relatively higher corrosion current of HAP/Ti composite than that of pure Ti coating in simulated body fluid indicates a good bioactivity for composite coating. In the present study, in vitro immersion test is carried out for various period of time and the formation of apatite layer on surface of composite coating proves the good bioactivity of the composite coating further. The cold sprayed HAP/Ti composite can be anticipated to be a promising load-bearing implant material for biomedical applications.

Sea surface temperature east of Australia: A predictor of tropical cyclone frequency over the western North Pacific?
BoTao Zhou,Xuan Cui
Chinese Science Bulletin , 2011, DOI: 10.1007/s11434-010-4157-5
Abstract: The relationship between sea surface temperature (SST) east of Australia and tropical cyclone frequency over the western North Pacific (WNPTCF) is analyzed by use of observation data. The WNPTCF from June to October is correlated negatively to spring SST east of Australia. When the spring SST is in the positive phase, a cyclonic circulation anomaly in the upper troposphere and an anticyclonic circulation anomaly in the lower troposphere prevail over the western North Pacific from June to October, concurrent with an anomalous atmospheric subsidence and an enlarged vertical zonal wind shear. These conditions are unfavorable for tropical cyclone genesis, and thus WNPTCF decreases. The negative phase of the spring SST east of Australia leads to more tropical cyclones over the western North Pacific. The spring SST east of Australia may give rise to simultaneous change in tropical atmospheric circulation via the teleconnection wave train, and then subsequently affect atmospheric circulation variation over the western North Pacific.

Zhou Xuan,

电子与信息学报 , 1984,
Abstract: The proximity focused microchannel plate (MCP) image intensifier can be used as a fast optical shutter, due to its high temporal and spatial resolution, large spectral and input intensity range, high gain, and possibility of transient recording of single-shot events.A microchannel plate image intensifier combining with a gating pulse generator constitutes the simplest image converter camera with high gain and fast response. Three different gating manners for a typical second generation converter tube (18 mm,ITT-F4111 type) are compared. A new control circuit for gating the photocathode of the image intensifier is developed, and it generates high amplitude nanosecond pulses. The experimental result shows that a camera exposure time of about 2 ns has been obtained with this gating generator. The matching of the gating generator with the image intensifier is also discussed. a simple and efficient method is presented to eliminate the multi-exposure effect which must be avoided in single-shot photography.
New Braided T-Categories over Weak Crossed Hopf Group Coalgebras
Xuan Zhou,Tao Yang
Abstract and Applied Analysis , 2013, DOI: 10.1155/2013/626394
Abstract: Let be a weak crossed Hopf group coalgebra over group ; we first introduce a kind of new α-Yetter-Drinfel’d module categories for and use it to construct a braided -category . As an application, we give the concept of a Long dimodule category for a weak crossed Hopf group coalgebra with quasitriangular and coquasitriangular structures and obtain that is a braided -category by translating it into a weak Yetter-Drinfel'd module subcategory . 1. Introduction Braided crossed categories over a group (i.e., braided ), introduced by Turaev [1] in the study of homotopy quantum field theories, are braided monoidal categories in Freyd-Yetter categories of crossed -sets [2]. Such categories play an important role in the construction of homotopy invariants. By using braided Virelizier [3, 4] constructed Hennings-type invariants of flat group bundles over complements of links in the 3-sphere. Braided also provide suitable mathematical formalism to describe the orbifold models of rational conformal field theory (see [5]). The methods of constructing braided can be found in [5–8]. Especially, in [8], Zunino gave the definition of -Yetter-Drinfel’d modules over Hopf group coalgebras and constructed a braided , then proved that both the category of Yetter-Drinfel’d modules and the center of the category of representations of as well as the category of representations of the quantum double of are isomorphic as braided Furthermore, in [6], Wang considered the dual setting of Zunino’s partial results, formed the category of Long dimodules over Hopf group algebras, and proved that the category is a braided of Yetter-Drinfel’d category . Weak multiplier Hopf algebras, as a further development of the notion of the well-known multiplier Hopf algebras [9], were introduced by Van Daele and Wang [10]. Examples of such weak multiplier Hopf algebras can be constructed from weak Hopf group coalgebras [10, 11]. Furthermore, the concepts of weak Hopf group coalgebras are also regard as a natural generalization of weak Hopf algebras [12, 13] and Hopf group coalgebras [14]. In this paper, we mainly generalize the above constructions shown in [6, 8], replacing their Hopf group coalgebras (or Hopf group algebras) by weak crossed Hopf group coalgebras [11] and provide new examples of braided . This paper is organized as follows. In Section 1, we recall definitions and properties related to braided -categories and weak crossed Hopf group coalgebras. In Section 2, let be a weak crossed Hopf group coalgebra over group ; is a fixed element in . We first introduce the concept of a (left-right)
Dynamics of Order Reconstruction in a Nanoconfined Nematic Liquid Crystal with a Topological Defect
Xuan Zhou,Zhidong Zhang
International Journal of Molecular Sciences , 2013, DOI: 10.3390/ijms141224135
Abstract: At the wall in a hybrid nematic cell with strong anchoring, the nematic director is parallel to one wall and perpendicular to the other. Within the Landau-de Gennes theory, we have investigated the dynamics of s = ±1/2 wedge disclinations in such a cell, using the two-dimensional finite-difference iterative method. Our results show that with the cell gap decreasing, the core of the defect explodes, and the biaxiality propagates inside the cell. At a critical value of d c* ≈ 9ξ (where ξ is the characteristic length for order-parameter changes), the exchange solution is stable, while the defect core solution becomes metastable. Comparing to the case with no initial disclination, the value at which the exchange solution becomes stable increases relatively. At a critical separation of d c ≈ 6ξ, the system undergoes a structural transition, and the defect core merges into a biaxial layer with large biaxiality. For weak anchoring boundary conditions, a similar structural transition takes place at a relative lower critical value. Because of the weakened frustration, the asymmetric boundary conditions repel the defect to the weak anchoring boundary and have a relatively lower critical value of d a, where the shape of the defect deforms. Further, the response time between two very close cell gaps is about tens of microseconds, and the response becomes slower as the defect explodes.
Generalized Yetter-Drinfel'd module categories for regular multiplier Hopf algebras
Tao Yang,Xuan Zhou
Mathematics , 2013,
Abstract: For a regular multiplier Hopf algebra $A$, the Yetter-Drinfel'd module category ${}_{A}\mathcal{YD}^{A}$ is equivalent to the centre $Z({}_{A}\mathcal{M})$ of the unital left $A$-module category ${}_{A}\mathcal{M}$. Then we introduce the generalized $(\alpha, \beta)$-Yetter-Drinfel'd module categories ${}_{A}\mathcal{GYD}^{A}(\alpha, \beta)$, which are treated as components of a braided $T$-category. Especially when $A$ is a coFrobenius Hopf algebra, ${}_{A}\mathcal{YD}^{A}(\alpha, \beta)$ is isomorphic to the unital $\hat{A} \bowtie A(\alpha, \beta)$-module category ${}_{\hat{A} \bowtie A(\alpha, \beta)}\mathcal{M}$. Finally for a Yetter-Drinfel'd $A$-module algebra $H$, we introduce Yetter-Drinfel'd $(H, A)$-module category, which is a monoidal.
Transmutation Theory and Quantization Approach for Quantum Groupoids
Xuan Zhou,Tao Yang
Mathematics , 2011,
Abstract: Let $H$ and $L$ be quantum groupoids. If $H$ has a quasitriangular structure, then we show that $L$ induces a Hopf algebra $C_{L}(L_s)$ in the category $_{H}\mathcal{M}$, which generalizes the transmutation theory introduced by Majid. Furthermore, if $H$ is commutative, we can construct a Hopf algebra $C_H(H_s)_F$ in the category $_H\mathcal{M}_F$ for a weak invertible unit 2-cocycle $F$, which generalizes the results in \cite{D83}. Finally, we consider the relation between two Hopf algebras: $C_H(H_s)_F$ and $C_{\widetilde H}(\widetilde{H}_s)$, and obtain that they are isomorphic as objects in the category $_{\widetilde H}\mathcal{M}$, where $(\widetilde H, \widetilde{\mathcal{R}})$ is a new quasitriangular quantum groupoid induced by $(H, \mathcal{R})$.
On Synchronization of Pinning-Controlled Networks with Reducible and Asymmetric Coupling Matrix  [PDF]
Xuan Zhou, Hui Feng, Jianwen Feng, Yi Zhao
Communications and Network (CN) , 2011, DOI: 10.4236/cn.2011.32014
Abstract: This paper investigates the synchronization of directed networks whose coupling matrices are reducible and asymmetrical by pinning-controlled schemes. A strong sufficient condition is obtained to guarantee that the synchronization of the kind of networks can be achieved. For the weakly connected network, a method is presented in detail to solve two challenging fundamental problems arising in pinning control of complex networks: (1) How many nodes should be pinned? (2) How large should the coupling strength be used in a fixed complex network to realize synchronization? Then, we show the answer to the question that why all the diagonal block matrices of Perron-Frobenius normal matrices should be pinned? Besides, we find out the relation between the Perron-Frobenius normal form of coupling matrix and the differences of two synchronization conditions for strongly connected networks and weakly connected ones with linear coupling configuration. Moreover, we propose adaptive feedback algorithms to make the coupling strength as small as possible. Finally, numerical simulations are given to verify our theoretical analysis.

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