The Experts below are selected from a list of 110802 Experts worldwide ranked by ideXlab platform
Mohd Amran Mohd Radzi - One of the best experts on this subject based on the ideXlab platform.
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operation of three level inverter based shunt active power filter under nonideal grid voltage conditions with dual Fundamental Component extraction
IEEE Transactions on Power Electronics, 2018Co-Authors: Yap Hoon, Mohd Amran Mohd Radzi, Mohd Khair Hassan, Nashiren Farzilah MailahAbstract:In this paper, a new reference current generation method is proposed for effective harmonics mitigation and reactive power compensation of three-level neutral-point diode clamped inverter-based shunt active power filter (SAPF) under nonideal grid voltage conditions. The proposed method is named as dual Fundamental Component extraction algorithm. In operation, the proposed algorithm extracts at the same time, the desired Fundamental current and voltage Components for generating reference current and synchronization phases, respectively. As a result, the proposed algorithm is able to generate reference current that ensures in phase operation of SAPF with the operating power system, without depending on any phase-locked loop elements. Besides, the proposed algorithm employs self-tuning filter (STF) for accurate computation of the Fundamental Components. Design concept and effectiveness of the proposed algorithm are thoroughly studied and evaluated in MATLAB–Simulink. Additionally, a laboratory prototype utilizing TMS320F28335 digital signal processor is built to validate its feasibility. Encouraging findings obtained from both simulation and experimental works demonstrate effectiveness of the proposed algorithm under both ideal and nonideal grid voltage conditions.
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Dual Function of Unified Adaptive Linear Neurons Based Fundamental Component Extraction Algorithm for Shunt Active Power Filter Operation
International Review of Electrical Engineering (IREE), 2015Co-Authors: Nor Farahaida Abdul Rahman, Mohd Amran Mohd Radzi, Azura Che Soh, Norman Mariun, Nasrudin Abd RahimAbstract:Unified Adaptive Linear Neurons (ADALINEs) based Fundamental Component extraction algorithm is presented for better operation of a Shunt Active Power Filter (SAPF). The proposed algorithm is developed for dual functionality. The first role is to generate a reference current for the SAPF. Whilst, the second function is to coordinate the phase of the generated reference current with the phase of any operating power system. Consequently, the operation of the SAPF will be synchronized with the operating power system. Hence, it replaces the necessity of using conventional synchronization algorithms such as Phase-Locked Loops (PLLs) and Zero-Crossing Detectors (ZCDs). In this work, the proposed algorithm is executed using an integration of two ADALINEs based Fundamental current and voltage extraction algorithms. Also, it implements the modified on-line Widrow-Hoff (W-H) weight updating algorithm for high speed extraction process. The effectiveness of the proposed algorithm has been verified in both simulation and experimental works.
Massimo Mischi - One of the best experts on this subject based on the ideXlab platform.
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Effects of a mono-disperse bubble population on the cumulative phase delay between second harmonic and Fundamental Component
The Journal of the Acoustical Society of America, 2017Co-Authors: Libertario Demi, Hessel Wijkstra, Wim Van Hoeve, Ruud J. G. Van Sloun, Massimo MischiAbstract:A positive cumulative phase delay (CPD) between the second-harmonic and Fundamental Component of ultrasound waves is a marker specific to ultrasound contrast agents. Dynamic contrast-enhanced ultrasound images generated by using this marker have already been reported in the literature. However, only results obtained with a poly-disperse contrast agent (SonoVue®) have been presented. In this study, we compared CPD values obtained with standard SonoVue® and with a mono-disperse contrast agent (MDCA); the latter consisted of 4-μm microbubbles produced with a MicroSphere Creator®. The same as with SonoVue®, MDCA microbubbles were made of SF6 gas encapsulated in a monolayer phospholipid shell. An ULA-OP research platform equipped with an LA332 linear-array probe was employed to image a dedicated gelatin flow-phantom. Different frequencies (1.5 to 3.5 MHz) with a mechanical index of 0.7 were used. Images were reconstructed in a tomographic fashion, and the contrast to tissue ratio (CTR) evaluated. When imaging ...
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contrast enhanced ultrasound tomography by means of the cumulative phase delay between second harmonic and Fundamental Component
Internaltional Ultrasonics Symposium, 2015Co-Authors: Libertario Demi, Hessel Wijkstra, Ruud J. G. Van Sloun, Massimo MischiAbstract:Standard dynamic contrast-enhanced ultrasound (DCE-US) imaging detects and estimates ultrasound-contrastagent (UCA) concentration based on the amplitude of the harmonic Components generated during ultrasound (US) propagation through UCAs. However, harmonic generation is not specific to UCAs, as it also occurs for US propagating through tissue. Moreover, nonlinear artifacts affect standard DCE-US imaging, causing contrast to tissue ratio (CTR) reduction, and resulting in possible tissue misclassification and misinterpretation of UCA concentrations. Especially for US tomography, no contrast-specific modality exists. Recently, a new marker for UCAs was discovered. A cumulative phase delay (CPD) between the second harmonic (2H) and Fundamental (F0) Component is in fact observable for US propagating through UCAs, and is absent in tissue. In this paper, CPD based tomographic US images are presented and compared to standard US tomography. By testing its applicability on gelatin phantoms with cylindrical cavities filled with a SonoVue® UCA dilution, we showed that CPD tomography outperforms standard US tomography by speed of sound and dispersion analysis, yielding a superior CTR: 32.2 dB vs. 0.06 and 4.6 dB, respectively.
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Observed cumulative time delay between second harmonic and Fundamental Component of pressure wave fields propagating through ultrasound contrast agents
The Journal of the Acoustical Society of America, 2013Co-Authors: Libertario Demi, G Giovanna Russo, Hessel Wijkstra, Massimo MischiAbstract:Several studies on the propagation velocity of pressure wave fields through ultrasound contrast agents (UCAs) have been reported in the literature. However, the variation of propagation velocity between the Fundamental and the second harmonic Component generated during the propagation of ultrasound through UCAs has, to our knowledge, not been studied yet. To this scope, dedicated transmission and backscattering measurements of pressure wave fields propagating through SonoVue and Definity contrast agents, are analyzed. Results show the occurrence of a cumulative delay between the time signals related to the second harmonic and Fundamental Component, suggesting a smaller propagation velocity for the second harmonic as compared to the Fundamental Component. Moreover, this time delay increases with increasing UCA concentration and propagation path length of ultrasound trough microbubbles, depends on mechanical index and frequency, and, most importantly, is not observed in the absence of UCAs. These results may be relevant to contrast-enhanced ultrasonography, opening up to new possibilities to increase contrast-to-tissue ratios and to quantify UCA concentrations.
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Observed cumulative time delay between second harmonic and Fundamental Component of pressure wave fields propagating through ultrasound contrast agents
2013Co-Authors: Libertario Demi, Hessel Wijkstra, Giovanna Russo, Massimo MischiAbstract:To our knowledge, despite several studies on the propagation velocity of pressure wave fields through ultrasound contrast agents (UCAs) have been conducted, the variation of propagation velocity between the Fundamental and second harmonic Component generated during the propagation of ultrasound through UCAs has not been studied yet. For this purpose, transmission and backscattering measurements of pressure wave fields propagating through gelatin phantoms containing cylindrical cavities of different diameter, filled with different concentrations [0 to 240 μL/L] of SonoVue® contrast agent, are conducted. Different frequencies [2, 2.5, and 3 MHz] and mechanical indices [0.05, 0.1, and 0.2] are investigated. Moreover, measurements obtained with Definity® contrast agent are also analyzed. Results show the occurrence of a cumulative delay between the time signals related to the second harmonic and Fundamental Component, suggesting a smaller propagation velocity for the second harmonic as compared to the Fundamental Component. Moreover, this delay increases with increasing microbubble concentration and diameter of the cavity, it depends on mechanical index and frequency, and, most importantly, it is not observed in the absence of UCAs. These results may be relevant for contrast-enhanced ultrasonography, providing new possibilities to increase contrast-to-tissue ratios and to quantify UCA concentration
Nasrudin Abd Rahim - One of the best experts on this subject based on the ideXlab platform.
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Dual Function of Unified Adaptive Linear Neurons Based Fundamental Component Extraction Algorithm for Shunt Active Power Filter Operation
International Review of Electrical Engineering (IREE), 2015Co-Authors: Nor Farahaida Abdul Rahman, Mohd Amran Mohd Radzi, Azura Che Soh, Norman Mariun, Nasrudin Abd RahimAbstract:Unified Adaptive Linear Neurons (ADALINEs) based Fundamental Component extraction algorithm is presented for better operation of a Shunt Active Power Filter (SAPF). The proposed algorithm is developed for dual functionality. The first role is to generate a reference current for the SAPF. Whilst, the second function is to coordinate the phase of the generated reference current with the phase of any operating power system. Consequently, the operation of the SAPF will be synchronized with the operating power system. Hence, it replaces the necessity of using conventional synchronization algorithms such as Phase-Locked Loops (PLLs) and Zero-Crossing Detectors (ZCDs). In this work, the proposed algorithm is executed using an integration of two ADALINEs based Fundamental current and voltage extraction algorithms. Also, it implements the modified on-line Widrow-Hoff (W-H) weight updating algorithm for high speed extraction process. The effectiveness of the proposed algorithm has been verified in both simulation and experimental works.
Nashiren Farzilah Mailah - One of the best experts on this subject based on the ideXlab platform.
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operation of three level inverter based shunt active power filter under nonideal grid voltage conditions with dual Fundamental Component extraction
IEEE Transactions on Power Electronics, 2018Co-Authors: Yap Hoon, Mohd Amran Mohd Radzi, Mohd Khair Hassan, Nashiren Farzilah MailahAbstract:In this paper, a new reference current generation method is proposed for effective harmonics mitigation and reactive power compensation of three-level neutral-point diode clamped inverter-based shunt active power filter (SAPF) under nonideal grid voltage conditions. The proposed method is named as dual Fundamental Component extraction algorithm. In operation, the proposed algorithm extracts at the same time, the desired Fundamental current and voltage Components for generating reference current and synchronization phases, respectively. As a result, the proposed algorithm is able to generate reference current that ensures in phase operation of SAPF with the operating power system, without depending on any phase-locked loop elements. Besides, the proposed algorithm employs self-tuning filter (STF) for accurate computation of the Fundamental Components. Design concept and effectiveness of the proposed algorithm are thoroughly studied and evaluated in MATLAB–Simulink. Additionally, a laboratory prototype utilizing TMS320F28335 digital signal processor is built to validate its feasibility. Encouraging findings obtained from both simulation and experimental works demonstrate effectiveness of the proposed algorithm under both ideal and nonideal grid voltage conditions.
Li Tian-yun - One of the best experts on this subject based on the ideXlab platform.
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A Method to Detect Fundamental Component by Symmetrical Component under Inter-Harmonics
Power system technology, 2006Co-Authors: Li Tian-yunAbstract:A method to detect Fundamental Component by symmetrical Component under inter-harmonics is presented. In this method the three-phase harmonic current signals containing inter-harmonics is projected on system frequency within the period of Fundamental Component to obtain Fundamental Component and harmonic Components, and symmetrical Component transform of positive, negative and zero sequences are conducted to implement the decoupling of Fundamental Component and harmonic Components, and then Fundamental Component can be obtained by low pass filter, finally the instantaneous value of Fundamental Component can be solved by inverse transformation of positive, negative and zero sequences. The presented method is not affected by such factors as the disequilibrium of both amplitudes and initial phase of three-phase currents, voltage distortion and frequency deviation. This method possesses better anti-interference performance which is independent for each phase. Simulation results show that the presented method is effective.
