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Xiangtan, China

Xiangtan University, or XTU , is a university located in Xiangtan, Hunan. It was founded in 1958 and is organized into 22 Schools and Departments.Xiangtan University, located in Xiangtan City, the home town of Mao Zedong, is a comprehensive university operating under the joint support of the Hunan Provincial Government and the Ministry of Education. It is one of China’s first educational institutes authorized to award master’s degrees and is also among the earliest schools approved to enroll overseas students and students of national defense. In an evaluation conducted by the Ministry of Education, the university’s bachelor degree education was rated as excellent. Wikipedia.

Wang J.,Guizhou University | Zhou Y.,Xiangtan University
Nonlinear Analysis: Real World Applications | Year: 2011

In this paper, we prove the existence and controllability results for fractional semilinear differential inclusions involving the Caputo derivative in Banach spaces. The results are obtained by using fractional calculation, operator semigroups and BohnenblustKarlin's fixed point theorem. At last, an example is given to illustrate the theory. © 2011 Elsevier Ltd. All rights reserved.

Pei Y.,Xiangtan University | Zeng X.C.,University of Nebraska - Lincoln
Nanoscale | Year: 2012

Unlike bulk materials, the physicochemical properties of nano-sized metal clusters can be strongly dependent on their atomic structure and size. Over the past two decades, major progress has been made in both the synthesis and characterization of a special class of ligated metal nanoclusters, namely, the thiolate-protected gold clusters with size less than 2 nm. Nevertheless, the determination of the precise atomic structure of thiolate-protected gold clusters is still a grand challenge to both experimentalists and theorists. The lack of atomic structures for many thiolate-protected gold clusters has hampered our in-depth understanding of their physicochemical properties and size-dependent structural evolution. Recent breakthroughs in the determination of the atomic structure of two clusters, [Au 25(SCH 2CH 2Ph) 18] q (q = -1, 0) and Au 102(p- MBA) 44, from X-ray crystallography have uncovered many new characteristics regarding the gold-sulfur bonding as well as the atomic packing structure in gold thiolate nanoclusters. Knowledge obtained from the atomic structures of both thiolate-protected gold clusters allows researchers to examine a more general "inherent structure rule" underlying this special class of ligated gold nanoclusters. That is, a highly stable thiolate-protected gold cluster can be viewed as a combination of a highly symmetric Au core and several protecting gold-thiolate "staple motifs", as illustrated by a general structural formula [Au] a+a′[Au(SR) 2] b[Au 2(SR) 3] c[Au 3(SR) 4] d[Au 4(SR) 5] e where a, a′, b, c, d and e are integers that satisfy certain constraints. In this review article, we highlight recent progress in the theoretical exploration and prediction of the atomic structures of various thiolate-protected gold clusters based on the "divide-and-protect" concept in general and the "inherent structure rule" in particular. As two demonstration examples, we show that the theoretically predicted lowest-energy structures of Au 25(SR) 8 - and Au 38(SR) 24 (-R is the alkylthiolate group) have been fully confirmed by later experiments, lending credence to the "inherent structure rule". This journal is © 2012 The Royal Society of Chemistry.

Wang J.,Guizhou University | Zhou Y.,Xiangtan University
Nonlinear Analysis: Real World Applications | Year: 2011

This paper concerns the existence of mild solutions for semilinear fractional evolution equations and optimal controls in the α-norm. A suitable α-mild solution of the semilinear fractional evolution equations is introduced. The existence and uniqueness of α-mild solutions are proved by means of fractional calculus, singular version Gronwall inequality and LeraySchauder fixed point theorem. The existence of optimal pairs of system governed by fractional evolution equations is also presented. Finally, an example is given for demonstration. © 2010 Published by Elsevier Ltd. All rights reserved.

Chen Y.,South China Normal University | Lu Z.,Xiangtan University
Computer Methods in Applied Mechanics and Engineering | Year: 2010

In this paper we study the fully discrete mixed finite element methods for quadratic convex optimal control problem governed by semilinear parabolic equations. The space discretization of the state variable is done using usual mixed finite elements, whereas the time discretization is based on difference methods. The state and the co-state are approximated by the lowest order Raviart-Thomas mixed finite element spaces and the control is approximated by piecewise constant elements. By applying some error estimates techniques of mixed finite element methods, we derive a priori error estimates both for the coupled state and the control approximation. Finally, we present a numerical example which confirms our theoretical results. © 2009.

Tang X.,Xiangtan University
Journal of Physics Condensed Matter | Year: 2011

A toroidal carbon nanowire (TCNW) model is proposed for an ideal one-dimensional mesoscopic ring, consisting of a toroidal carbon nanotube (TCN) and an encapsulated carbon ring, of which the electronic structure and thus the persistent current (Ipc) are investigated within the tight-binding formalism. The tube-ring interactions lead to a charge transfer from the inner ring to the outer TCN, and thus the Fermi level rises and the band overlaps in a certain flux range. In zigzag TCNWs with a metallic TCN, the actual magnetic response, the amplitude and the period of Ipc in the primary carbon ring are concealed by those in the resultant TCNW; in zigzag TCNWs with a semiconducting TCN, Ipc exhibits the same behavior as that in their primary carbon rings. The results show that Ipc in the sample ring depends strongly on the surrounding environment and thus a semiconducting or insulating matrix may provide a desired environment for measuring persistent current in mesoscopic rings. © 2011 IOP Publishing Ltd.

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