The Experts below are selected from a list of 324 Experts worldwide ranked by ideXlab platform
Xingyao Yin - One of the best experts on this subject based on the ideXlab platform.
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Broadband Seismic Inversion for Low-Frequency Component of the Model Parameter
IEEE Transactions on Geoscience and Remote Sensing, 2018Co-Authors: Zhaoyun Zong, Yurong Wang, Xingyao YinAbstract:Seismic inversion is an important approach in parameters estimation in the fields of geosciences. The low-Frequency Component of the model parameter plays an important role in seismic inversion. The emergence of broadband seismic data acquisition and processing technologies is pushing the attention of the low Frequency to a new level. With the review of the research status of the estimation of the low-Frequency models in history and the low-Frequency Component contained in the complex Frequency domain, a novel broadband seismic Bayesian inversion approach in the complex Frequency domain is proposed to implement the estimation of the low-Frequency Component of the model parameter. The proposed approach makes full use of the advantage of broadband seismic data and the low-Frequency Component of the damped wave fields in the complex Frequency domain. The kernel function of the proposed inversion approach is built with Bayesian inference. Synthetic examples demonstrate the feasibility and robustness of the proposed inversion approach in the estimation of the low-Frequency Component of the model parameter. A field data example verifies the feasibility and reasonability of the proposed inversion approach in application. Finally, the estimated low-Frequency Component of the model parameter is utilized as the initial model for the suggested seismic Bayesian inversion method in time domain. Model and field data examples further verify the effectiveness and superiority of the proposed inversion method in the final estimation of the model parameter by comparing with the conventional inversion approach.
George E Billman - One of the best experts on this subject based on the ideXlab platform.
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low Frequency Component of the heart rate variability spectrum a poor marker of sympathetic activity
American Journal of Physiology-heart and Circulatory Physiology, 1999Co-Authors: Melanie S Houle, George E BillmanAbstract:The low-Frequency Component of the heart rate variability spectrum (0.06–0.10 Hz) is often used as an accurate reflection of sympathetic activity. Therefore, interventions that enhance cardiac symp...
Jin-lung Guan - One of the best experts on this subject based on the ideXlab platform.
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real time measurement approach for tracking the actual coefficient of spl delta v spl delta v sub 10 of electric arc furnace
IEEE Transactions on Power Delivery, 2004Co-Authors: Jin-lung GuanAbstract:This investigation develops a new definition of the voltage fluctuation (/spl Delta/V) electric arc furnace. Analysis of voltage flicker spectrum in the 0.25-30-Hz range reveals that the magnitude of each modulation Frequency Component decreases with Frequency, while the standard deviation of each Frequency Component is high. From the statistics of electric arc furnace real time test data, the loads can be classified as weakly stationary processes, but lack a Gauss probability distribution. Traditionally, the equivalent 10-Hz voltage fluctuation (/spl Delta/V/sub 10/) value can be obtained from /spl Delta/V/3.6. However, the real world tests and statistics indicate that the ratios of /spl Delta/V//spl Delta/V/sub 10/ are 1.8, not 3.6.
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Real-time measurement approach for tracking the actual coefficient of /spl Delta/V//spl Delta/V/sub 10/ of electric arc furnace
IEEE Transactions on Power Delivery, 2004Co-Authors: Jin-lung GuanAbstract:This investigation develops a new definition of the voltage fluctuation (/spl Delta/V) electric arc furnace. Analysis of voltage flicker spectrum in the 0.25-30-Hz range reveals that the magnitude of each modulation Frequency Component decreases with Frequency, while the standard deviation of each Frequency Component is high. From the statistics of electric arc furnace real time test data, the loads can be classified as weakly stationary processes, but lack a Gauss probability distribution. Traditionally, the equivalent 10-Hz voltage fluctuation (/spl Delta/V/sub 10/) value can be obtained from /spl Delta/V/3.6. However, the real world tests and statistics indicate that the ratios of /spl Delta/V//spl Delta/V/sub 10/ are 1.8, not 3.6.
Sang-hee Kang - One of the best experts on this subject based on the ideXlab platform.
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A DC offset removal algorithm based on AR model
Journal of International Council on Electrical Engineering, 2018Co-Authors: Sang-hee KangAbstract:ABSTRACTThis work proposes an auto-regressive (AR) model-based algorithm that can eliminate the adverse influence of the exponentially decaying DC offset in the phasor estimation process using discrete Fourier transform (DFT). The proposed algorithm comprises three stages: DFT, AR model implementation, and compensation. First, DFT can eliminate all harmonic Components and estimate the phasor of the fundamental Frequency Component. Second, the AR model is used to calculate the error caused by the exponentially decaying DC offset in the phasor value estimated by DFT. A second-order AR model that uses three successively estimated phasor values is utilized. Finally, the phasor of the fundamental Frequency Component can be accurately estimated by compensating the error caused by the exponentially decaying DC offset. The performance of the proposed algorithm is evaluated for a-phase to ground fault on a 154 kV 25 km overhead transmission line. Electromagnetic Transients Program is used to generate fault signals...
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fourier transform based modified phasor estimation method immune to the effect of the dc offsets
Power and Energy Society General Meeting, 2009Co-Authors: Sang-hee Kang, Peter A. Crossley, Yong Cheol KangAbstract:This paper proposes a Fourier transform-based modified phasor estimation method to eliminate the adverse influence of the exponentially decaying dc offsets when Discrete Fourier Transform (DFT) is used to calculate the phasor of the fundamental Frequency Component in a relaying signal. By subtracting the result of odd-sample-set DFT from the result of even-sample-set DFT, the information of dc offsets can be obtained. Two dc offsets in a secondary relaying signal are treated as one dc offset which is piecewise approximated in one cycle data window. The effect of the dc offsets can be eliminated by the approximated dc offset. The performance of the proposed algorithm is evaluated by using computer-simulated signals and EMTP-generated signals. The algorithm is also tested on a hardware board with TMS320C32 microprocessor. The evaluation results indicate that the proposed algorithm can estimate the accurate phasor of the fundamental Frequency Component regardless of not only the primary decaying dc offset but also the secondary decaying dc offset caused by CT circuit itself including its burden.
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fourier transform based modified phasor estimation method immune to the effect of the dc offsets
IEEE Transactions on Power Delivery, 2009Co-Authors: Sang-hee Kang, Peter A. Crossley, Yong Cheol KangAbstract:This paper proposes a Fourier transform-based modified phasor estimation method to eliminate the adverse influence of the exponentially decaying dc offsets when discrete Fourier transform (DFT) is used to calculate the phasor of the fundamental Frequency Component in a relaying signal. By subtracting the result of odd-sample-set DFT from the result of even-sample-set DFT, the information of dc offsets can be obtained. Two dc offsets in a secondary relaying signal are treated as one dc offset which is piecewise approximated in one cycle data window. The effect of the dc offsets can be eliminated by the approximated dc offset. The performance of the proposed algorithm is evaluated by using computer-simulated signals and Electromagnetic Transients Program-generated signals. The algorithm is also tested on a hardware board with TMS320C32 microprocessor. The evaluation results indicate that the proposed algorithm can estimate the accurate phasor of the fundamental Frequency Component regardless of not only the primary decaying dc offset but also the secondary decaying dc offset caused by CT circuit itself including its burden.
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An Analytic Method for Measuring Accurate Fundamental Frequency Components
IEEE Power & Energy Magazine, 2002Co-Authors: Soon-ryul Nam, Sang-hee Kang, Jong-keun ParkAbstract:This paper proposes an analytic method for measuring the accurate fundamental Frequency Component of a fault current signal distorted with a DC-offset, a characteristic Frequency Component, and harmonics. The proposed algorithm is composed of four stages: sine filter, linear filter, Prony's method, and measurement. The sine filter and the linear filter eliminate harmonics and the fundamental Frequency Component, respectively. Then Prony's method is used to estimate the parameters of the DC-offset and the characteristic Frequency Component. Finally, the fundamental Frequency Component is measured by compensating the sine-filtered signal with the estimated parameters. The performance evaluation of the proposed method is presented for a-phase to ground faults on a 345 kV 200 km overhead transmission line. The electromagnetic transient program (EMTP) is used to generate fault current signals under different fault locations and fault inception angles. It is shown that the analytic method accurately measures the fundamental Frequency Component regardless of the characteristic Frequency Component as well as the DC-offset.
Toshiaki Shiomi - One of the best experts on this subject based on the ideXlab platform.
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augmented very low Frequency Component of heart rate variability during obstructive sleep apnea
Sleep, 1996Co-Authors: Izumi Hirota, Ryujiro Sasanabe, Toshiaki Shiomi, Masato Maekawa, Christian Guilleminault, Tadashi KobayashiAbstract:Abstract After documenting the presence of obstructive sleep apnea syndrome (OSAS) through polysomnographic monitoring, we performed simultaneous ambulatory recordings of electrocardiogram, oronasal airflow, and pulse oximetry on 12 OSAS patients with normal autonomic nervous function for a period of 24 hours. The power spectrum of heart rate variability was investigated before and during treatments using dental appliances. Freuquency domain analysis showed that the very low Frequency Component of heart rate (0.008-0.04 Hz) was increased in OSAS patients and that a very low Frequency peak appeared during episodes of obstructive sleep apnea. The increase in very low Frequency identification was synchronized with episodes of absence of air exchange or hypoxemia (decreased arterial oxygen saturation) that occurred repeatedly at a cycle length of 25-120 seconds in our subjects. Frequency domain analysis of heart rate variability before and during prosthetic mandibular advancement treatment showed that only the very low Frequency was significantly decreased during prosthetic mandibular advancement treatment, whereas the other frequencies, i.e. high, low, and ultralow Frequency Component values, showed no significant changes. Time domain analysis of heart rate variability before and during prosthetic mandibular advancement treatment showed no significant changes in any of these parameters. Frequency domain analysis of heart rate variability during nocturnal sleep, especially investigation of very low Frequency and very low Frequency peak, can be a noninvasive low-cost approach to diagnose and even better monitor subjects undergoing treatment at home, particularly considering that R-R intervals can be extracted from pulse oximetry and that analysis software programs are already commercially available.