Wardkein, Paramote
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Wardkein, Paramote
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Wardkein, P.
Wardkein, Pramote
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paramote.wa@kmitl.ac.th
39 results
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Item type:Publication, Direct frequency estimation based adaptive algorithm for a second-order adaptive FIR notch filter(2008-02-01); 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. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, A Photoplethysmographic Signal Isolated from an Additive Motion Artifact by Frequency Translation(2018-08-01); Acquiring a precise percentage of oxygen saturation (SpO2) from a finger-probe pulse oximeter is dependent on both artifact-free red and infrared photoplethysmoghaphic (PPG) signals. Nonetheless, in real-life situations, these PPG signals are corrupted by a motion artifact (MA) signal that is generated from either finger or hand movement. To resolve this MA interference, the cause of the adulteration of PPG signals by the MA signal is examined. The MA signal is found to behave like an additive noise. Additionally, the frequency responses of the MA and PPG signals show that these signals are in the same frequency band. Hence, instead of direct current, a sinusoidal wave alternating current is proposed to drive an LED source in order to shift the PPG frequency band away from the MA frequency band. Experimentally, a commercial finger-probe pulse oximeter is employed. To determine the performance of the presented scheme, the resulting PPG signals are compared with those from employing the old-fashioned LED-driving method. In addition, the accuracy is verified by computing the SpO2 value. The results reveal that the proposed approach successfully retains the fundamental morphologies of the PPG structures when motion occurs. Moreover, the calculated SpO2 values from the proposed technique provide an average error of approximately 1.4%, whereas the conventional method yields a mean error approximately 4.2%. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Heart detection and diagnosis based on ECG and EPCG relationships(2011-08-26); ; Yupapin, PPA 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. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Effects of hot air temperature on moisture reduction and drying time of turmeric in a closed-system herb dryer: kinetics and models(2023-11-01); Chantrawongphisal, BorisutThe primary objective of this research was to devise a model focused on the drying kinetics of turmeric, utilizing a closed-system herb dryer to facilitate energy conservation. Drying turmeric within this closed-system herb dryer involves a heat source—specifically, an electric coil heater powered at 3500 W and a humidity controller. The drying condition includes an air volume of 0.039 kg/s, the temperature at 40, 50, and 60 °C with initial moisture of the turmeric at 667.53 %db. The result of drying turmeric was analyzed using a thin-layer drying model for 8 models: Newton, Page, Logistic, Henderson and Pabis, Logarithmic, Two-Term, Approximation of Diffusion, Midill et al. The result shows that Midill et al. equation was the best model for predicting the drying behavior of turmeric. Therefore, this insinuates that the Midill model is superior to its contemporaneous counterparts in terms of accuracy. It offered the highest coefficient of determination R <sup>2</sup> (0.9998, 0.9996, 0.9999), the most root mean square error (RMSE) (3.39×10<sup>−9</sup>, 2.37×10<sup>−5</sup>, 3.10×10<sup>−5</sup>), the last chi-square χ <sup>2</sup> (3.39×10<sup>−9</sup>, 2.85×10<sup>−5</sup>, 3.99×10<sup>−5</sup>), and a temperature of 40, 50, and 60 °C, respectively. The study revealed that implementing a closed-system herb dryer could potentially manufacture high-value commodities while preserving their fundamental attributes. The closed-system herb dryer has been ingeniously designed as a proficient approach to diminish the drying time and improve the end product’s quality. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Reliability optimization of topology communication network design using an improved ant colony optimization(2009-09-01) - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Wide-band amplitude control of the second-order oscillator circuit(2008-10-01); ; Koseeyaporn, PoolsakIn this paper, a new analysis technique of an ordinary second-order oscillator which is based on multi-time concept is proposed. This mathematical analysis results in a new closed-form solution of a system complete response. It is found that amplitude of the natural response is not constant but varied with the forced response of the system. For a constant forcing function proposed, the new analysis is identical to the conventional analysis. In the case of time-varying forcing function, however, it is different from the conventional approach. Based on such analysis, it implies that the amplitude of a second-order oscillator can easily be controlled by forced response of the system. Hence, the obtained result based on the proposed analysis technique provides a proper mathematical solution for the system, especially in a time-varying forcing function. Moreover, the mathematical analysis for the wide-band characteristic of a second-order oscillator is also described. The experimental results demonstrate the responses of the oscillator which agree well between the theoretical and simulation results. © 2007 Elsevier GmbH. All rights reserved. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Novel Double Slope Frequency Shift Chirp Symbol(2024-01-01); One of the most significant concerns in serial digital communication is the synchronization of data bits between the transmitter and receiver. Therefore, the preferred coding symbols should contain an inherited clock signal. The cyclic-shift chirp, which is primarily used in long-range systems, employs a single slope in a symbol, which contains few information for synchronization. Hence, two new forms of cyclic-shift chirp symbols are proposed herein. The associated coding schemes are based on the use of a dual slope within one symbol. Synchronization is inherited in the coding symbol using a dual slope. Additionally, both proposed coding schemes utilize the same decoding technique. The decoded chirp symbol is in the form of a pulse width modulation signal, which can be used for synchronization and retrieving data bits from their duty cycle. The simulation results show that the coding and decoding processes of the proposed coding schemes align with those of a theoretical framework. The error performance analysis for the proposed detection scheme is given and the results of error probability analysis are consistent with the simulation results. Moreover, under a Rayleigh fading channel, the proposed coding schemes provide superior performance compared with other comparable coding schemes. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, DSSZ-SM: A Simplified Chirp Coding Scheme with Inherent Clock Synchronization(2026-06-01) - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Indirect frequency estimation based on second-order adaptive FIR notch filter(2009-07-01); This paper deals with estimating the frequency of sinusoidal signal buried in broad band noise. The simple unbiased indirect frequency estimation (IFE) algorithm is proposed for a second-order adaptive finite impulse response (FIR) notch filter with constrained zeros. The technique of estimating input noise variance is employed to remove the bias existing in the estimated filter parameter. Also, the difference equation for the convergence of the expectation of the estimated parameter and the closed-form of steady state estimation mean square error (MSE) are derived. In addition, extensive simulations are conducted to corroborate the efficiency of the proposed estimator with the theoretical analysis. © 2009 Elsevier B.V. All rights reserved. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Current controlled oscillator based on translinear conveyors(1996-07-18)