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517 results on '"Hui, S. Y."'

3. Effect of Forming Process on Microstructure and Shape Memory Effect of Ni50Mn34In14Co2 Alloy.

Author

Dong, G. F., Hui, S. Y., Sun, G. Y., Yan, H. B., Gao, L., and Gao, Z. Y.

Subjects
SHAPE memory effect, MARTENSITIC transformations, MICROSTRUCTURE, ALLOYS, IRON-manganese alloys, SHAPE memory alloys
Abstract

The effects of different forming process on the microstructure, martensitic transformation, and mechanical properties of the Ni50Mn34In14Co2 (numbers indicate at.%) alloys were investigated in detail. The results show that the microstructure of Ni50Mn34In14Co2 alloy consists of the matrix and the second phase by powder hot forging technology under the forces in different directions and spark plasma sintering (SPS), and the prepared sample has obvious preferred orientation by applied force in the three directions. The grain and the second phase of prepared sample were obviously refined by the hot forging technology. The martensitic transformation behavior was almost unchanged by different forming process. In addition, the shape memory effect of prepared Ni50Mn34In14Co2 alloy was significantly enhanced by different forming processes. [ABSTRACT FROM AUTHOR]

Published
2023
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15. Exponential Modulation Integral Observer for Online Detection of the Fundamental and Harmonics in Grid-Connected Power Electronics Equipment

Author

Lam, Hin Sang, Li, Peng, Chen, Boli, Ng, Wai Man, Parisini, Thomas, and Hui, S. Y. R.

Subjects
Active power filters (APFs), fundamental extraction, harmonics detection
Abstract

Harmonic current estimation is required in active power filters for compensation purposes. The most efficient way of calculating the total harmonic current up to the infinite order is to subtract the fundamental component from the distorted current. Direct determination of the fundamental component of a distorted current of mains frequency was realized recently with a third-order modulation integral observer. This article shows that using an exponential modulation function (Exp-MF) for the integral observer will: 1) significantly enhance the robustness of the observer against noise and 2) automatically remove the low-frequency envelope arising from the D/A and A/C sampling processes compared to previous polynomial modulation function. These new and advantageous features are supported with detailed analysis and experimental verification. The robust observer can be implemented in grid-connected power electronics circuits that require the instantaneous information of the fundamental and/or harmonic currents. Practical comparative tests with the adaptive notch filter and recursive discrete Fourier transform (DFT) methods in an active power filter have confirmed the good performance under both the steady and dynamic states of the proposed Exp-MF integral observer.

Published
2021

35. An Adaptive Observer-based Robust Estimator of Multi-sinusoidal Signals

Author

Chen, B., Pin, G., W. M., Ng, Lee, C. K., Hui, S. Y. R., Parisini, T., Chen, B., Pin, G., Ng, W. M., Lee, C. K., Hui, S. Y. R., and Parisini, T.

Subjects
0209 industrial biotechnology, Computer science, 0906 Electrical And Electronic Engineering, Robust statistics, Internal model, Estimator, 020206 networking & telecommunications, 02 engineering and technology, Signal, Stability (probability), Computer Science Applications, Phase-locked loop, Industrial Engineering & Automation, 020901 industrial engineering & automation, Adaptive observers, Control and Systems Engineering, Control theory, 0102 Applied Mathematics, Bounded function, 0202 electrical engineering, electronic engineering, information engineering, Fading, Electrical and Electronic Engineering, 0913 Mechanical Engineering
Abstract

This paper presents an adaptive-observer-based robust estimation methodology of the amplitudes, frequencies, and phases of biased multi-sinusoidal signals in the presence of bounded perturbations on the measurement. The parameters of the sinusoidal components are estimated online, and the update laws are individually controlled by an excitation-based switching logic enabling the update of a parameter only when the measured signal is sufficiently informative. This way doing, the algorithm is able to tackle the problem of overparameterization (i.e., when the internal model accounts for a number of sinusoids that is larger than the true spectral content) or temporarily fading sinusoidal components. The stability analysis proves the existence of a tuning parameter set, for which the estimator's dynamics are input-to-state stable with respect to bounded measurement disturbances. The performance of the proposed estimation approach is evaluated and compared with the other existing tools by extensive simulation trials and real-time experiments.

Published
2018

48. A Parallel Prefiltering Approach for the Identification of a Biased Sinusoid Signal: Theory and Experiments

Author

Chen, B., Pin, G., Ng, W. M., Hui, S. Y. R., PARISINI, Thomas, Chen, B., Pin, G., Ng, W. M., Hui, S. Y. R., and Parisini, Thomas

Subjects
input-to-state stability, sinusoid estimation, adaptive algorithms, input-to-state stability, adaptive algorithms, sinusoid estimation
Abstract

The problem of estimating the amplitude, frequency, and phase of an unknown sinusoidal signal from a noisy-biased measurement is addressed in this paper by a family of parallel prefiltering schemes. The proposed methodology consists in using a pair of linear filters of specified order to generate a suitable number of auxiliary signals that are used to estimate—in an adaptive way—the frequency, the amplitude, and the phase of the sinusoid. Increasing the order of the prefilters improves the noise immunity of the estimator, at the cost of an increase of the computational complexity. Among the whole family of estimators realizable by varying the order of the filters, the simple parallel prefilters of orders 2 C 2 and 3 C 3 are discussed in detail, being the most attractive from the implementability point of view. The behavior of the two algorithms with respect to bounded external disturbances is characterized by input-to-state stability arguments. Finally, the effectiveness of the proposed technique is shown both by comparative numerical simulations and by a real experiment addressing the estimation of the frequency of the electrical mains from a noisy voltage measurement.

Published
2015

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