Pipatsart, Surasak

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Pipatsart, Surasak
Alternative Name
Pipatsart, S.
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surasak.pi@kmitl.ac.th

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    Geometrically distributed one-dimensional photonic crystals for all angle optical filters
    (2012-11-01)
    Teeka, C.
    ;
    Pipatsart, S.
    ;
    Yupapin, P. P.
    We present the general formulation of light reflection using a series of one-dimensional (1D) photonic crystals (PCs) with different periods, which is made of nonabsorptive materials of any refractive indices.To have a large bandgap, the spectral range of reflection, the periods of 1D PCs must be distributed in a geometrical progression with a common ratio, r, smaller than a maximum value of r <inf>c</inf>. In this letter, the exact expressions for rc, the bandgap to mid gap ratio of the PC heterostructure and the minimum number of PCs to achieve the desired range of bandgap in single and all angles of incidence have been presented. The proposed method can be used to design the optical filters for vast range of applications such as ultraviolet (UV) filters (i.e., sunglasses, eye safety glasses, UV photography filters) and visible light filters. © 2012 Wiley Periodicals, Inc.
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    An investigation of dark soliton behaviors within the nonlinear micro and nano ring resonators
    (2010-11-01)
    Sangwara, N.
    ;
    Teeka, C.
    ;
    Pipatsart, S.
    ;
    Yupapin, P. P.
    We firstly propose the interesting results of a dark soliton pulse propagating within the nonlinear micro and nano waveguides. The system consists of nonlinear micro and nano ring resonators, whereas the dark soliton is input into the system and traveling within the waveguide. A continuous dark soliton pulse is chopped to be the smaller pulses by the nonlinear effects known as chaos. The nonlinear behaviors such as chaos, bistability and bifurcation are analyzed and discussed. The power amplification is the property that can be used to perform the long distance link, where the security is the dominant reason. © 2009 Elsevier GmbH. All rights reserved.
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    Multitweezers generation using dark soliton pulses and applications
    (2011-08-01)
    Jukgoljun, B.
    ;
    Pipatsart, S.
    ;
    Jalil, M. A.
    ;
    Yupapin, P. P.
    ;
    Ali, J.
    Multi-dark soliton pulses have been successfully generated by using forward and backward pumping of the S-band erbium doped fiber in the fiber optic loop, where the Stimulated Brillouin Scattering (SBS) is a nonlinear interaction between pump fields with Stokes field through acoustic wave. Results obtained have shown that the dark soliton trains can be generated and configured as the multi-optical tweezers. The advantage is that the generated tweezers are in the form of dynamic tweezers, where they can transmit/transport via the soliton communication link. The single dark soliton is also experimentally generated by using the different fiber optic scheme. We have also theoretically shown that the dynamic tweezers can be controlled and tuned, which is available for trapping and transportation in the communication link via a wavelength router. The quantum states of the transported atoms/molecules by the dynamic tweezers can be performed by using the quantum processing unit incorporating in the system. © 2010 Elsevier GmbH. All rights reserved.
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    Acoustic cardiac signals analysis: A Kalman filter-based approach
    (2012-12-05)
    Salleh, Sheik Hussain
    ;
    Hussain, Hadrina Sheik
    ;
    Swee, Tan Tian
    ;
    Ting, Chee Ming
    ;
    Noor, Alias Mohd
    Auscultation of the heart is accompanied by both electrical activity and sound. Heart auscultation provides clues to diagnose many cardiac abnormalities. Unfortunately, detection of relevant symptoms and diagnosis based on heart sound through a stethoscope is difficult. The reason GPs find this difficult is that the heart sounds are of short duration and separated from one another by less than 30 ms. In addition, the cost of false positives constitutes wasted time and emotional anxiety for both patient and GP. Many heart diseases cause changes in heart sound, waveform, and additional murmurs before other signs and symptoms appear. Heart-sound auscultation is the primary test conducted by GPs. These sounds are generated primarily by turbulent flow of blood in the heart. Analysis of heart sounds requires a quiet environment with minimum ambient noise. In order to address such issues, the technique of denoising and estimating the biomedical heart signal is proposed in this investigation. Normally, the performance of the filter naturally depends on prior information related to the statistical properties of the signal and the background noise. This paper proposes Kalman filtering for denoising statistical heart sound. The cycles of heart sounds are certain to follow first-order Gauss-Markov process. These cycles are observed with additional noise for the given measurement. The model is formulated into state-space form to enable use of a Kalman filter to estimate the clean cycles of heart sounds. The estimates obtained by Kalman filtering are optimal in mean squared sense. © 2012 Zeng et al, publisher and licensee Dove Medical Press Ltd.