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Search Results: 1 - 10 of 28126 matches for " Xin-Chu Weng "
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Antioxidant Activity of Polyphenolic Compounds from Dalbergia odorifera T. Chen
Jian-Ping Hou,Hou Wu,Chi-Tang Ho,Xin-Chu Weng
Pakistan Journal of Nutrition , 2011,
Abstract: Seven compounds were isolated from Dalbergia odorifera T. Chen and their antioxidant activities were studied with Oil Stability Index (OSI) method, reducing power and radical scavenging methods. The compounds were identified by spectroscopic methods as (1) pinocembrin (2) biochanin A (3) sativanone (4) biochanin B (5) naringenin (6) 3'-hydroxymelanettin and (7) eriodictoyl. Results showed that compounds 6 and 7 exhibited stronger antioxidant activity than commonly used synthetic antioxidant BHT in the presented study.
Symbolic analysis for some planar piecewise linear maps
Xin-Chu Fu,Peter Ashwin
Physics , 2003,
Abstract: In this paper a class of linear maps on the 2-torus and some planar piecewise isometries are discussed. For these discontinuous maps, by introducing codings underlying the map operations, symbolic descriptions of the dynamics and admissibility conditions for itineraries are given, and explicit expressions in terms of the codings for periodic points are presented.
Infinite-Dimensional Linear Dynamical Systems with Chaoticity
Xin-Chu Fu,Jinqiao Duan
Physics , 1998,
Abstract: The authors present two results on infinite-dimensional linear dynamical systems with chaoticity. One is about the chaoticity of the backward shift map in the space of infinite sequences on a general Fr\'{e}chet space. The other is about the chaoticity of a translation map in the space of real continuous functions. The chaos is shown in the senses of both Li-Yorke and Wiggins. Treating dimensions as freedoms, the two results imply that in the case of an infinite number of freedoms, a system may exhibit complexity even when the action is linear. Finally, the authors discuss physical applications of infinite-dimensional linear chaotic dynamical systems.
Topology Identification of General Dynamical Network with Distributed Time Delays

WU Zhao-Yan,FU Xin-Chu,

中国物理快报 , 2009,
Abstract: General dynamical networks with distributed time delays are studied. The topology of the networks are viewed as unknown parameters, which need to be identified. Some auxiliary systems (also called the network estimators) are designed to achieve this goal. Both linear feedback control and adaptive strategy are applied in designing these network estimators. Based on linear matrix inequalities and the Lyapunov function method, the sufficient condition for the achievement of topology identification is obtained. This method can also better monitor the switching topology of dynamical networks. Illustrative examples are provided to show the effectiveness of this method.
Symbolic Representations of Iterated Maps
Xin-Chu Fu,Weiping Lu,Peter Ashwin,Jinqiao Duan
Physics , 2000,
Abstract: This paper presents a general and systematic discussion of various symbolic representations of iterated maps through subshifts. We give a unified model for all continuous maps on a metric space, by representing a map through a general subshift over usually an uncountable alphabet. It is shown that at most the second order representation is enough for a continuous map. In particular, it is shown that the dynamics of one-dimensional continuous maps to a great extent can be transformed to the study of subshift structure of a general symbolic dynamics system. By introducing distillations, partial representations of some general continuous maps are obtained. Finally, partitions and representations of a class of discontinuous maps, piecewise continuous maps are discussed, and as examples, a representation of the Gauss map via a full shift over a countable alphabet and representations of interval exchange transformations as subshifts of infinite type are given.
Invariant sets for discontinuous parabolic area-preserving torus maps
Peter Ashwin,Xin-Chu Fu,Takashi Nishikawa,Karol Zyczkowski
Physics , 1999, DOI: 10.1088/0951-7715/13/3/317
Abstract: We analyze a class of piecewise linear parabolic maps on the torus, namely those obtained by considering a linear map with double eigenvalue one and taking modulo one in each component. We show that within this two parameter family of maps, the set of noninvertible maps is open and dense. For cases where the entries in the matrix are rational we show that the maximal invariant set has positive Lebesgue measure and we give bounds on the measure. For several examples we find expressions for the measure of the invariant set but we leave open the question as to whether there are parameters for which this measure is zero.
Investigation of a Unified Chaotic System and Its Synchronization by Simulations*

WU Qing-Chu,FU Xin-Chu,Michael Small,

中国物理快报 , 2010,
Abstract: We investigate a unified chaotic system and its synchronization including feedback synchronization and adaptive synchronization by numerical simulations. We propose a new dynamical quantity denoted by K, which connects adaptive synchronization and feedback synchronization, to analyze synchronization schemes. We find that K can estimate the smallest coupling strength for a unified chaotic system whether it is complete feedback or one-sided feedback. Based on the previous work, we also give a new dynamical method to compute the leading Lyapunov exponent.
Epidemic thresholds in a heterogenous population with competing strains

Wu Qing-Chu,Fu Xin-Chu,Yang Meng,

中国物理 B , 2011,
Abstract: Among many epidemic models, one epidemic disease may transmit with the existence of other pathogens or other strains from the same pathogen. In this paper, we consider the case where all of the strains obey the susceptible-infected-susceptible mechanism and compete with each other at the expense of common susceptible individuals. By using the heterogenous mean-field approach, we discuss the epidemic threshold for one of two strains. We confirm the existence of epidemic threshold in both finite and infinite populations subject to underlying epidemic transmission. Simulations in the Barabasi-Albert (BA) scale-free networks are in good agreement with the analytical results.
Fitness-driven deactivation in network evolution
Xin-Jian Xu,Xiao-Long Peng,Michael Small,Xin-Chu Fu
Computer Science , 2010, DOI: 10.1088/1742-5468/2010/12/P12020
Abstract: Individual nodes in evolving real-world networks typically experience growth and decay --- that is, the popularity and influence of individuals peaks and then fades. In this paper, we study this phenomenon via an intrinsic nodal fitness function and an intuitive aging mechanism. Each node of the network is endowed with a fitness which represents its activity. All the nodes have two discrete stages: active and inactive. The evolution of the network combines the addition of new active nodes randomly connected to existing active ones and the deactivation of old active nodes with possibility inversely proportional to their fitnesses. We obtain a structured exponential network when the fitness distribution of the individuals is homogeneous and a structured scale-free network with heterogeneous fitness distributions. Furthermore, we recover two universal scaling laws of the clustering coefficient for both cases, $C(k) \sim k^{-1}$ and $C \sim n^{-1}$, where $k$ and $n$ refer to the node degree and the number of active individuals, respectively. These results offer a new simple description of the growth and aging of networks where intrinsic features of individual nodes drive their popularity, and hence degree.

HUANG Qing-hua,SONG Xin-chu,

地球学报 , 1992,
Abstract: The stress is an important factor in the research on the crustal stability of a given region. Its occurring and developing is closely related to the earthquake and fault action. So it's an important method to evaluate the crustal stability of a given region from the stress. Mathematical stimulating model has been established according to the seismic and geological structure and recent crustal acting and so on in Beijing area (Fig. 1). On the above-mentioned method the authors calcaulated the field of recent structural stress and the fields of regulating influence as the increasing of fractural action in Beijing area(Fig. 4-Fig. 10), and established the field of comprehensive reguting influence as the increasing of fractural action on the basis of every field of regulating influence (Fig. 11). The authors also analysis and compare the relative grade of crustal stability of Beijing area and the relative grade of crustal stability of Beijing city in Beijing area, and get a conclusion that the increasing of Nankao-Sunhe fault action is rather affecting to the crustal stability of Beijing city.
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