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Search Results: 1 - 10 of 95419 matches for " Chen Zeng-Qiang "
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Low dimensional chaos in the AT and GC skew profiles of DNA sequences

Zhou Qian,Chen Zeng-Qiang,

中国物理 B , 2010,
Abstract: This paper investigates the existence of low-dimensional deterministic chaos in the AT and GC skew profiles of DNA sequences. It has taken DNA sequences from eight organisms as samples. The skew profiles are analysed using continuous wavelet transform and then nonlinear time series methods. The invariant measures of correlation dimension and the largest Lyapunov exponent are calculated. It is demonstrated that the AT and GC skew profiles of these DNA sequences all exhibit low dimensional chaotic behaviour. It suggests that chaotic properties may be ubiquitous in the DNA sequences of all organisms.
Evolutionary Pseudo-Relaxation Learning Algorithm for Bidirectional Associative Memory
Sheng-Zhi Du,Zeng-Qiang Chen,Zhu-Zhi Yuan,
Sheng-Zhi Du
,Zeng-Qiang Chen,and Zhu-Zhi Yuan

计算机科学技术学报 , 2005,
Abstract: This paper analyzes the sensitivity to noise in BAM (Bidirectional Associative Memory), and then proves the noise immunity of BAM relates not only to the minimum absolute value of net inputs (MAV) but also to the variance of weights associated with synapse connections. In fact, it is a positive monotonically increasing function of the quotient of MAV divided by the variance of weights. Besides, the performance of pseudo-relaxation method depends on learning parameters (λ and ξ), but the relation of them is not linear. So it is hard to find a best combination of λ and ξ which leads to the best BAM performance. And it is obvious that pseudo-relaxation is a kind of local optimization method, so it cannot guarantee to get the global optimal solution. In this paper, a novel learning algorithm EPRBAM (evolutionary psendo-relaxation learning algorithm for bidirectional association memory) employing genetic algorithm and pseudo-relaxation method is proposed to get feasible solution of BAM weight matrix. This algorithm uses the quotient as the fitness of each individual and employs pseudo-relaxation method to adjust individual solution when it does not satisfy constraining condition any more after genetic operation. Experimental results show this algorithm improves noise immunity of BAM greatly. At the same time, EPRBAM does not depend on learning parameters and can get global optimal solution. Supported by the National Natural Science Foundation of China (Grant No.60374037)
A novel chaotic system with one source and two saddle-foci in Hopfield neural networks

Chen Peng-Fei,Chen Zeng-Qiang,Wu Wen-Juan,

中国物理 B , 2010,
Abstract: This paper presents the finding of a novel chaotic system with one source and two saddle-foci in a simple three-dimensional (3D) autonomous continuous time Hopfield neural network. In particular, the system with one source and two saddle-foci has a chaotic attractor and a periodic attractor with different initial points, which has rarely been reported in 3D autonomous systems. The complex dynamical behaviours of the system are further investigated by means of a Lyapunov exponent spectrum, phase portraits and bifurcation analysis. By virtue of a result of horseshoe theory in dynamical systems, this paper presents rigorous computer-assisted verifications for the existence of a horseshoe in the system for a certain parameter.
Hyperchaos--chaos--Hyperchaos Transition in a Class of On--Off Intermittent Systems Driven by a Family of Generalized Lorenz Systems

ZHOU Qian,CHEN Zeng-Qiang,YUAN Zhu-Zhi,

中国物理快报 , 2008,
Abstract: Blowout bifurcation in nonlinear systems occurs when a chaotic attractor lying in some symmetric subspace becomes transversely unstable. A class of five-dimensional continuous autonomous systems is considered, in which a two-dimensional subsystem is driven by a family of generalized Lorenz systems. The systems have some common dynamical characters. As the coupling parameter changes, blowout bifurcations occur in these systems and brings on change of the systems' dynamics. After the bifurcation the phenomenon of on--off intermittency appears. It is observed that the systems undergo a symmetric hyperchaos--chaos--hyperchaos transition via or after blowout bifurcations. An example of the systems is given, in which the drive system is the Chen system. We investigate the dynamical behaviour before and after the blowout bifurcation in the systems and make an analysis of the transition process. It is shown that in such coupled chaotic continuous systems, blowout bifurcation leads to a transition from chaos to hyperchaos for the whole systems, which provides a route to hyperchaos
Local bifurcation analysis of a four-dimensional hyperchaotic system

Wu Wen-Juan,Chen Zeng-Qiang,Yuan Zhu-Zhi,

中国物理 B , 2008,
Abstract: Local bifurcation phenomena in a four-dimensional continuous hyperchaotic system, which has rich and complex dynamical behaviours, are analysed. The local bifurcations of the system are investigated by utilizing the bifurcation theory and the centre manifold theorem, and thus the conditions of the existence of pitchfork bifurcation and Hopf bifurcation are derived in detail. Numerical simulations are presented to verify the theoretical analysis, and they show some interesting dynamics, including stable periodic orbits emerging from the new fixed points generated by pitchfork bifurcation, coexistence of a stable limit cycle and a chaotic attractor, as well as chaos within quite a wide parameter region.
Implementation of LT codes based on chaos

Zhou Qian,Li Liang,Chen Zeng-Qiang,Zhao Jia-Xiang,

中国物理 B , 2008,
Abstract: Fountain codes provide an efficient way to transfer information over erasure channels like the Internet. LT codes are the first codes fully realizing the digital fountain concept. They are asymptotically optimal rateless erasure codes with highly efficient encoding and decoding algorithms. In theory, for each encoding symbol of LT codes, its degree is randomly chosen according to a predetermined degree distribution, and its neighbours used to generate that encoding symbol are chosen uniformly at random. Practical implementation of LT codes usually realizes the randomness through pseudo-randomness number generator like linear congruential method. This paper applies the pseudo-randomness of chaotic sequence in the implementation of LT codes. Two Kent chaotic maps are used to determine the degree and neighbour(s) of each encoding symbol. It is shown that the implemented LT codes based on chaos perform better than the LT codes implemented by the traditional pseudo-randomness number generator.
K-Means Clustering Based on Genetic Algorithm
基于遗传算法的K均值聚类分析

WANG Chang CHEN Zeng-Qiang YUAN Zhu-Zhi,
王敞
,陈增强

计算机科学 , 2003,
Abstract: This paper proposes a K-Means clustering method based on genetic algorithm. We compare our method with the traditional K-Means method and clustering method based on simple genetic algorithm. The comparison proves that our method achieves a better result than the other two. The drawback of this method is a comparably slower speed in clustering.
Phase transitions and elementary excitations in spin-1 Bose gases with Raman induced spin-orbit coupling
Zeng-Qiang Yu
Physics , 2015,
Abstract: We study the ground state phase diagram and the quantum phase transitions in spin-1 Bose gases with Raman induced spin-orbit coupling. In addition to the Bose-Einstein condensates with uniform density, three types of stripe condensation phases that simultaneously break the U(1) and the translation symmetry are identified in presence of spin-dependent interactions. The transitions between these phases are characterized by the spin magnetization and different crystalline orders, and the occurrences of the various tricritical points are predicted. The excitation spectra in the plane-wave phase and the zero-momentum phase show rich roton-maxon structures, and their instabilities indicate the tendency to develop crystalline orders. We propose the atomic gas of $^{23}$Na could be a candidate for observing the stripe condensate with high contrast fringes.
Equation of state and phase transition in spin-orbit-coupled Bose gases at finite temperature: A perturbation approach
Zeng-Qiang Yu
Physics , 2014, DOI: 10.1103/PhysRevA.90.053608
Abstract: We study two-component Bose gases with Raman induced spin-orbit coupling via a perturbation approach at finite temperature. For weak coupling, free energy is expanded in terms of Raman coupling strength up to the second order, where the coefficient (referred to as Raman susceptibility) is determined according to linear response theory. The equation of state for the stripe phase and the plane-wave phase are obtained in Popov approximation, and the first order transition between these two phases is investigated. As temperature increases, we find the phase boundary bends toward the stripe phase side in most temperature regions, which implies the ferromagnetic order is more robust than the crystalline order in presence of thermal fluctuations. Our results qualitatively agree with the recent experimental observation in rubidium atomic gases. A method to measure the Raman susceptibility through the two-photon Bragg scattering experiment is also discussed.
Ground-state phase diagram and critical temperature of two-component Bose gases with Rashba spin-orbit coupling
Zeng-Qiang Yu
Physics , 2013, DOI: 10.1103/PhysRevA.87.051606
Abstract: Ground-state phase diagram of two-component Bose gases with Rashba spin-orbit coupling is determined via a variational approach. A phase in which the fully polarized condensate occupies zero momentum is identified. This zero-momentum phase competes with the spin density wave phase when interspecies interaction is stronger than intraspecies interaction, and the former one is always the ground state for weak spin-orbit coupling. When the energies of these two phases are close, there is a phase separation between them. At finite temperature, such a zero-momentum condensation can be induced by a ferromagnetic phase transition in normal state. The spontaneous spin polarization removes the degeneracy of quasiparticles' energy minima, and consequently the modified density of state accommodates a Bose condensation to appear below a critical temperature.
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