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Author: search.filters.author.Paithoonwattanakij, KittiHas files: No

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    Fractional dynamics in calcium oscillation model
    (2015-01-01)
    Suansook, Yoothana
    ;
    Paithoonwattanakij, Kitti
    The calcium oscillations have many important roles to perform many specific functions ranging from fertilization to cell death. The oscillation mechanisms have been observed in many cell types including cardiac cells, oocytes, and hepatocytes. There are many mathematical models proposed to describe the oscillatory changes of cytosolic calcium concentration in cytosol. Many experiments were observed in various kinds of living cells. Most of the experimental data show simple periodic oscillations. In certain type of cell, there exists the complex periodic bursting behavior. In this paper, we have studied further the fractional chaotic behavior in calcium oscillations model based on experimental study of hepatocytes proposed by Kummer et al. Our aim is to explore fractional-order chaotic pattern in this oscillation model. Numerical calculation of bifurcation parameters is carried out using modified trapezoidal rule for fractional integral. Fractional-order phase space and time series at fractional order are present. Numerical results are characterizing the dynamical behavior at different fractional order. Chaotic behavior of the model can be analyzed from the bifurcation pattern.
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    Adaptive pixel-selection using chaotic map lattices for image cryptography
    (2014-02-24)
    Sittigorn, Jirasak
    ;
    Paithoonwattanakij, Kitti
    ;
    Surawatpunya, Charray
    Chaotic theory has been used in cryptography application for generating a sequence of data that is close to pseudorandom number based on an adjusted initial condition and a parameter. However, data recovery becomes a crucial problem due to the precision of the parameters. This difficulty leads to limited usage of Chaotic-based cryptography especially for error sensitive applications such as voice cryptography. In order to enhance the encryption security and overcome this limitation, an Adaptive Pixel-Selection using Chaotic Map Lattices (APCML) is proposed. In APCML, the encryption sequence has been adaptively selected based on chaos generator. Moreover, the chaotic transformation and normalization boundary have been revised to alleviate the rounding error and inappropriate normalization boundary problems. In the experiments, the measurement indices of originality preservation, visual inspection, and statistical analysis are used to evaluate the performance of the proposed APCML compared to that of the original CML. Consequently, the APCML algorithm offers greater performance with full recovery of the original message. © 2014 Copyright SPIE.
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    Dynamic of logistic model at fractional order
    (2009-12-01)
    Suansook, Yoothana
    ;
    Paithoonwattanakij, Kitti
    In this paper we have obtain the generalized form of the logistic model to arbitrary order using fractional calculus. The model is explained the population growth. The discrete version of the model have important role in studying the chaotic dynamic. The fractional calculus is feasible to evaluate the differential and integral of non integer order. This mathematical subject is helping fine tune analysis the chaotic properties of the logistic model. The numerical results show the Lyapunov exponent at various fractional orders. The positive Lyapunov exponent is indicate that the system is chaotic at fractional order. The periodic solutions of half fractional order are also present. ©2009 IEEE.
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    Bifurcation and lyapunov exponent in optical injected laser
    (2009-11-18)
    Suansook, Yoothana
    ;
    Paithoonwattanakij, Kitti
    The long distance communication today and high data rate transmission or higher bandwidth is feasible because of the optical fiber. The light propagates through fiber with less attenuation compare to electrical cables and not affected by electrical interference. The optical fiber with laser light source from semiconductor with injection locked has an important role in ultrahigh speed modulation in passive optical network. The irregularity pattern that arise in this type of laser are described by a set of deterministic equation which different from random fluctuation based on stochastic process is involved in system stability. In this paper, we study the chaotic property of optical injected lasers from the rate equations. The nonlinear dynamics property of the system can explain by the divergent rate of Lyapunov exponent and corresponding bifurcation diagram of related parameters. © 2009 IEEE.
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    Bifurcation and lyapunov exponent in orthogonal frequency division multiplexing
    (2008-12-01)
    Suansook, Yoothana
    ;
    Paithoonwattanakij, Kitti
    In this paper we have review the effective transmission technique called Orthogonal Frequency Division Multiplexing (OFDM) that use in high-speed bidirectional wireless data transfer and mobile data transfer. We have presented the bifurcation diagram and divergence rate of the function that arises in transmission technique the sinc function. The parameters are nonlinear indicators that explained how nonlinear system changes from periodic to chaotic behavior. Bifurcation diagram of the system is characterized when the system can exhibit the chaotic behavior. The Lyapunov exponent is characterized the divergence rate of dynamical system. © 2008 IEEE.
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    Wind farm generator control using self-tuning fuzzy controller
    (2006-01-01)
    Boonpirom, Nimit
    ;
    Paithoonwattanakij, Kitti
    In this paper, the wind farm generator controlled based on the squirrel cage induction using self-tuning fuzzy controller (SFLC) and conventional fuzzy controller (FLC) for voltage source converter (VSC) controlled in HVDC system are purposed. The performance of active power flow between induction generator and D.C link system via the sending side converter is improved by employing the SFLC of which scale factor of SFLC will be adjusted. Moreover, the FLC is also applied in the receiving side inverter in order to regulate the D.C. voltage level for the power balancing between D.C. system and grid line system. Finally, the simulation results show that the proposed method can effectively response to input power, output power, and D.C. voltage in case of steady state condition and the transient response when transmission line fault is occurred.
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    Power system stabilizer using self-tuning fuzzy controller
    (2005-12-01)
    Boonpirom, Nimit
    ;
    Paithoonwattanakij, Kitti
    This paper presents a design of Power System Stabilizer (PSS) using self-tuning fuzzy controller (SFLC). The power system stability (PSS) would be used to enhance transient stability by increasing terminal voltage. The objective of this paper is to adjust the terminal voltage by controlling excitation voltage. Self-tuning is applied to adjust the scaling factor to increase the sensitivity of controller. For the simulation results, a comparison between without PSS, with PSS, and SFLC on multi generator system is presented. The investigated result shows that the proposed method can effectively and efficiently response to power oscillation, transient terminal voltage and damping of generator rotor angle swings.
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    Image segmentation by fuzzy rule and Kohonen-constraint satisfaction fuzzy c-mean
    (1997-12-01)
    Khunkay, Suraphon
    ;
    Paithoonwattanakij, Kitti
    In this paper, we present a new algorithm that can segment a fuzzy data. This method is based on fuzzy logic and neural network, and a concept of constraint satisfaction problem (CSP). Firstly, pre-processing by creating a new pixel value on fuzzy rule has ability to describe the effect of neighborhood pixel in degree of membership value or linguistic variables which are utilized to activate a rule base. Secondly, the feature extraction employs Kohonen feature mapping (SOM), which can learn a feature without prior knowledge. Finally, a fuzzy c-mean (FCM) adapts to CSP structure by constituting a interconnection weight for all membership value of fuzzy c-mean with a global consistency situation. The result of this method have been tested on a varieties images.