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Heart detection and diagnosis based on ECG and EPCG relationships
(2011-08-26)
Phanphaisarn, W.
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Roeksabutr, A.
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Wardkein, P.
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Koseeyaporn, J.
;
Yupapin, PP
A new design of a system for preliminary detection of defective hearts is proposed which is composed of two subsystems, in which one is based on the relationship between the electrocardiogram (ECG) and phonocardiogram (PCG) signals. The relationship between both signals is determined as an impulse response (h(n)) of a system, where the decision is made based on the linear predictive coding coefficients of a heart's impulse response. The other subsystem uses a phase space approach, in which the mean squared error between the distance vectors of the phase space of the normal heart and abnormal heart is judged by the likelihood ratio test (Λ) value, on which the decision is made. The advantage of the proposed system is that a heart's diagnosis system based on the ECG and EPCG signals can lead to high performance heart diagnostics. © 2011 Phanphaisarn et al, publisher and licensee Dove Medical Press Ltd.
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Direct frequency estimation based adaptive algorithm for a second-order adaptive FIR notch filter
(2008-02-01)
Punchalard, R.
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Lorsawatsiri, A.
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Loetwassana, W.
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Koseeyaporn, J.
;
Wardkein, P.
This work deals with the problem of the frequency estimation of a sinusoidal signal corrupted by broad-band noise. The direct frequency estimation based adaptive algorithm for a second-order adaptive finite impulse response (FIR) notch filter (AFNF) is thus proposed. The proposed algorithm employs the bias removal technique to remove the bias existing in the estimated parameter. The performances including the rate of convergence and the mean square error (MSE) can be easily controlled by using only one parameter, i.e., step size parameter. Moreover, the proposed filter is simple to implement and suitable for real-time applications. In addition, the difference equations for the convergence in the mean and mean square, and the closed form expressions for the steady-state estimation bias and MSE are also carried out. Finally, the simulation results are provided to confirm the theoretical analysis. © 2007 Elsevier B.V. All rights reserved.
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Adaptive IIR notch filters based on new error criteria
(2008-03-01)
Punchalard, R.
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Lorsawatsiri, A.
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Koseeyaporn, J.
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Wardkein, P.
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Roeksabutr, A.
Modified indirect and direct plain gradient (MIPG and MDPG) algorithms using new error criteria for second-order adaptive IIR (infinite-impulse response) notch filters (ANFs) with constrained poles and zeros are proposed in this paper. The proposed techniques are based on modifying error functions of the standard indirect and direct ANFs. In this work, the proposed error criteria are modified as the mean value of the product of the two signals which are, respectively, produced by the FIR (finite-impulse response) and IIR sections of the ANFs. Due to a non-zero slope straight line-like characteristic of the new cost functions, the gradient based adaptive algorithm rapidly converges to an optimum solution resulting in faster convergence speed than that of the conventional method. The closed form expressions for steady-state estimation bias and mean square error (MSE) of the proposed algorithms are also carried out. In addition, extensive simulations of the proposed algorithms compared to other methods are provided to support the theoretical analyses. Although, there are some limitations in the proposed algorithms, however, the demonstrated results obtained from tested algorithms at the same condition confirm that the proposed MIPG and MDPG algorithms are superior to others in convergent speed. © 2007 Elsevier B.V. All rights reserved.
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Unbiased equation error adaptive IIR notch filter
(2007-12-01)
Punchalard, R.
;
Lorsawatsiri, A.
;
Loetwassana, W.
;
Koseeyaporn, J.
;
Wardkein, P.
This paper presents the unbiased gradient algorithm for the equation error adaptive IIR notch filter (UEANF). The proposed algorithm employs the bias removal technique to remove the bias existing in the estimated parameter, resulting in obtaining good estimate of the parameter. Moreover, the convergence property is improved as compared with the conventional adaptive IIR notch filter (ANF). The computer simulations are provided to confirm the performances of the proposed technique. ©2007 IEEE.
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Unbiased plain gradient algorithm for adaptive IIR notch filter with constrained poles and zeros
(2007-12-01)
Punchalard, R.
;
Lorsawatsiri, A.
;
Loetwassana, W.
;
Koseeyaporn, J.
;
Wardkein, P.
An unbiased plain gradient (UPG) algorithm for a constrained adaptive IIR notch filter (ANF) is presented in this paper. The proposed algorithm employs the bias removal technique to remove the bias existing in the estimate of the filter parameter, resulting in good estimation. The computer simulation results have shown that the proposed technique is unbiased. ©2007 IEEE.
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Steady-state analysis of an unbiased equation error adaptive IIR notch filter
(2007-12-01)
Punchalard, R.
;
Lorsawatsiri, A.
;
Loetwassana, W.
;
Koseeyaporn, J.
;
Wardkein, P.
This paper presents the steady-state analysis of the unbiased equation error adaptive IIR notch filter (UEANF). The difference equation for the convergence in the mean and the steady-state estimation bias is derived in closed forms. In addition, the simulation results are provided to confirm the theoretical analysis. Finally, the comparisons among the UEANF, the equation error adaptive IIR notch filter (EANF) and the output error adaptive IIR notch filter (ANF) based on theory as well as simulations have shown that the UEANF outperforms the ANF in its convergence rate and it provides unbiased estimate of the desired parameter as compared with the EANF and the ANF as well. ©2007 IEEE.
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Unbiased constrained adaptive IIR notch filter using direct frequency estimation algorithm
(2007-12-01)
Punchalard, R.
;
Lorsawatsiri, A.
;
Loetwassana, W.
;
Koseeyaporn, J.
;
Wardkein, P.
An unbiased constrained direct adaptive IIR notch filter is presented in this paper. The proposed algorithm employs the bias removal technique to remove the bias existing in the estimate of the filter parameter, resulting in good estimate of filter parameter. The theoretical analysis for the difference equation for the convergence in the mean is derived in closed form and confirmed by the computer simulations. ©2007 IEEE.
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An applicator for uniform heating using perpendicular slots on a concentric cylindrical cavity excited by perpendicular waveguides
(2006-05-01)
Sangdao, C.
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Roeksabutr, A.
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Krairiksh, M.
This paper presents an applicator that provides uniform heating by using perpendicular slots on a concentric cylindrical cavity excited by perpendicular waveguides. A concentric cylindrical cavity is designed to operate in both the TM<sup>Z</sup> and TE<sup>Z</sup> modes simultaneously. These modes are excited by perpendicular waveguides. The slot array of each mode is cut along the circumference of the inner surface of the applicator. Appropriate cavity dimension, slot length and position, improve the temperature distribution. The combination of two applicators aligned in an overlapped fashion realizes uniform temperature distribution in the material to be heated. This applicator is suitable for continuous microwave heating systems in agricultural product dryer.

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