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He Y.,Guangdong Polytechnic Normal University | Zhu X.,Sun Yat Sen University | Mihalache D.,Horia Hulubei National Institute of Physics and Nuclear Engineering | Liu J.,Guangdong Polytechnic Normal University | Chen Z.,Guangdong Polytechnic Normal University
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2012

We report the existence and stability of lattice solitons in parity-time (PT)-symmetric mixed linear-nonlinear optical lattices in Kerr media. We focus on studying the characteristic effects on soliton propagation in the semi-infinite gap if we consider different amplitudes of real and imaginary parts of both the linear refractive index modulation profile and of periodic nonlinearity-modulation spatial distribution. It was found that the combination of PT-symmetric linear and nonlinear lattices can stabilize lattice solitons and can provide unique soliton properties. It is revealed that the parameters of the linear lattice periodic potential play a significant role in controlling the extent of the stability domains and that the lattice solitons can stably propagate only in the low-power regime. © 2012 American Physical Society.


Xie X.,Sun Yat Sen University | Chen Y.,Guangdong Polytechnic Normal University | Yang K.,Sun Yat Sen University | Zhou J.,Sun Yat Sen University
Physical Review Letters | Year: 2014

The resolution limit of far-field optical microscopy is reexamined with a full vectorial theoretical analysis. A highly symmetric excitation optical field and optimized detection scheme are proposed to harness the total point-spread function for a microscopic system. Spatial resolution of better than 1/6λ is shown to be obtainable, giving rise to a resolution better than 100 nm with visible light excitation. The experimental measurement is applied to examine nonfluorescent samples. A lateral resolution of 1/5λ is obtained in truly far-field optical microscopy with a working distance greater than ∼500λ. Comparison is made for the far-field microscopic measurement with that of a nearfield scanning optical microscopy, showing that the proposed scheme provides a better image quality. © 2014 American Physical Society.


He Y.,Guangdong Polytechnic Normal University | Mihalache D.,Horia Hulubei National Institute of Physics and Nuclear Engineering | Mihalache D.,Academy of Romanian Scientists
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2013

We report the existence, stability, and rich dynamics of dissipative lattice solitons in optical media described by the cubic-quintic complex Ginzburg-Landau model with parity-time (PT) symmetric potentials. We focus on studying the generic spatial soliton propagation scenarios by changing (a) the linear loss coefficient in the complex Ginzburg-Landau model, (b) the amplitudes, and (c) the periods of real and imaginary parts of the complex-valued PT-symmetric optical lattice potential. Generically, it is found that if the period of the real part of the PT-symmetric optical lattice potential is close to π, the spatial solitons are tightly bound and they can propagate straightly along the lattice, while if the period of the real part of the PT-symmetric optical lattice potential is larger than π, the launched solitons are loosely bound and they can exhibit either a transverse (lateral) drift or a persistent swing around the input launching point due to gradient force arising from the spatially inhomogeneous loss. These latter features are intimately related to the dissipative nature of the system under consideration because they do not arise in the conservative counterpart of the dynamical model. These generic propagation scenarios can be effectively managed by properly changing the profile of the spatially inhomogeneous loss. © 2013 American Physical Society.


He Y.,Guangdong Polytechnic Normal University | Malomed B.A.,Tel Aviv University
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2013

We demonstrate the existence of two species of stable bright solitons, fundamental and dipole, in one-dimensional self-defocusing nonlocal media, with the local value of nonlinearity coefficient having one or several minima and growing at any rate faster than |x| at large values of coordinate x. The model can be derived for a slab optical waveguide with thermal nonlinearity. The most essential difference from the local counterpart of this system is the competition between two different spatial scales, one determining the modulation pattern of the nonlinearity coefficient and the other being the correlation length of the nonlocality. The competition is explicitly exhibited by an analytically obtained asymptotic form of generic solutions. Particular exact solutions are found analytically, and full soliton families are constructed in a numerical form. The multichannel settings, with two or three local minima of the nonlinearity coefficient, are considered here for both local and nonlocal models of the present type. States with multiple solitons launched into different channels are stable if the spacing between them exceeds a certain minimum value. A regime of stable Josephson oscillations of solitons between parallel channels is reported too. © 2013 American Physical Society.


He Y.,Guangdong Polytechnic Normal University | Mihalache D.,Horia Hulubei National Institute of Physics and Nuclear Engineering
Romanian Reports in Physics | Year: 2012

We provide a brief review of recent theoretical studies of optical spatial solitons in parity-time- (PT-) symmetric mixed linear-nonlinear lattices. The existence and stability of optical spatial solitons forming in PT-symmetric lattices with spatially periodic modulation of the Kerr nonlinearity are briefly overviewed. The linear optical lattices are considered to be either regular lattices or superlattices formed by the superposition of two periodic lattice potentials having commensurable lattice periods. The obtained results show that different kinds of linear optical lattices can profoundly affect soliton properties. In particular, by mixing linear and nonlinear optical lattices, a lot of unique spatial soliton properties were put forward. These features may find potential applications in all-optical signal processing and in high-speed circuits for optical communications systems.


Chen Y.,Guangdong Polytechnic Normal University
Nonlinear Dynamics | Year: 2016

Little seems to be known about the homoclinic orbits of hyperchaotic system. Through the deep researches of a 4D Lorenz-type hyperchaotic system, with the help of Fishing Principle, we obtain the existence conditions of homoclinic orbits of this hyperchaotic system. In order to justify the theoretical analysis, by using the numerical methods, a set of approximate bifurcation parameters and its corresponding homoclinic orbits are obtained. © 2016 Springer Science+Business Media Dordrecht


Yan H.,Guangdong Polytechnic Normal University
Applied Mechanics and Materials | Year: 2013

This paper presented a concept of knowledge entropy, and according to this concept the importance of attribute was defined. Algorithms for attribute reduction in rough sets based on concept of knowledge entropy was given, and an example analysis was done in this paper. For the example, the calculation result is coincident with the result calculated by using the traditional method of attribute reduction in rough set theory. © (2013) Trans Tech Publications, Switzerland.


Hu R.,Guangdong Polytechnic Normal University
Applied Mathematics and Information Sciences | Year: 2012

In this paper, a new approach using self-organizing Smart Grid systems is proposed to solve wireless sensor network dynamic channel-assignment. It concerns distribution among Grids whose task is to assign personal station to frequencies with respect to well known constraints. Grids only know their variables and the constraints affecting them, and have to negotiate to find a collective solution. The approach is based on a macro-level management taking the form of a hierarchical group of Grids in the network and handling all RACNs (Regional Radio Access Control Network) in a localized region regardless of the operating band. The approach defines cooperative self-organization as the process leading the collective to the solution: Grids can change the organization by their own decision to improve the state of the system. Our approach has been tested on Shanghai benchmarks of Channel Access Problem. The results obtained are equivalent to those of current existing methods with the benefits that our approach shows more efficiency in terms of flexibility and autonomy. © 2012 NSP Natural Sciences Publishing Cor.


Hu R.,Guangdong Polytechnic Normal University
Applied Mathematics and Information Sciences | Year: 2012

Providing stable compositions of Wireless Sensor Network Service (WSNS) is a challenging issue since the data stream architect often has only a limited control over the stability of the composed services. The architect can instead achieve stability by properly planning the data stream architecture. In this paper, we propose a formal approach which allows a data stream architect to perform stability analysis of WSNS-based security service. The approach exploits the concept of stability methods to evaluate the stability function of a wide class of data streams. The effect of the approach and the operation of the tool are demonstrated with respect to a case study of a business security infrastructure realized by simple security services. © 2012 NSP Natural Sciences Publishing Cor.


Liang Z.,Guangdong Polytechnic Normal University
Procedia Engineering | Year: 2012

Against the lack of existing answering system in terms of intelligence and human-computer interaction, on the basis of the CBR, proposed a design of intelligent question answering system, and study the key technologies of this program, include the automatic segmentation , questions similarity calculation, improve search efficiency. Experiments show that the program can improve the accuracy and intelligence of answering system, has some practical value. © 2011 Published by Elsevier Ltd.

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