The Experts below are selected from a list of 246 Experts worldwide ranked by ideXlab platform

Sascha Spors - One of the best experts on this subject based on the ideXlab platform.

  • Simultaneous Measurement of Spatial Room Impulse Responses from Multiple Sound Sources Using a Continuously Moving Microphone
    2018 26th European Signal Processing Conference (EUSIPCO), 2018
    Co-Authors: Nara Hahn, Sascha Spors
    Abstract:

    Continuous measurement techniques aim at identifying a large number of impulse responses from a Signal Captured by a moving microphone. In a recently proposed method, each sample of the Captured Signal is interpreted as a spatio-temporal sample of the sound field, and the individual impulse responses are computed by means of spatial interpolation. In the present study, the approach is extended towards multichannel cases. The superimposed sound field reproduced by multiple sources is recorded with one microphone, and the individual impulse responses are identified. To this end, the sound sources are excited with the same periodic perfect sequence, but a different amount of temporal shift is applied so that the identified impulse responses of different sources do not overlap. An anti-aliasing condition for the microphone speed is derived which is computed based on the spatial bandwidth of the sound field.

  • Continuous measurement of spatial room impulse responses using a non-uniformly moving microphone
    2017 IEEE Workshop on Applications of Signal Processing to Audio and Acoustics (WASPAA), 2017
    Co-Authors: Nara Hahn, Sascha Spors
    Abstract:

    The room impulse responses at multiple receiver positions can be measured efficiently with a continuously moving microphone. The acoustic system is periodically excited by a self-orthogonal Signal, called perfect sequence, and the microphone captures the sound field on a pre-defined path. As shown in recent studies by the authors, the Captured Signal constitutes a spatio-temporal sampling of the sound field, and the impulse responses can be obtained by a spatial interpolation. So far, a uniformly moving microphone was mainly considered for the measurement of spatial room impulse responses. In this paper, the method is applied to non-uniformly moving microphones thereby addressing more general cases. The proposed method is evaluated by numerical simulations where the spatial room impulse responses on a circle are measured using a microphone with a fluctuating angular speed. The accuracy of the impulse responses are compared for varying interpolation orders.

  • Comparison of continuous measurement techniques for spatial room impulse responses
    2016 24th European Signal Processing Conference (EUSIPCO), 2016
    Co-Authors: Nara Hahn, Sascha Spors
    Abstract:

    A large number of spatial room impulse responses can be measured efficiently by using a moving microphone in combination with a time-varying system identification method. The microphone moves on a predefined trajectory and captures the response of the acoustic system which is periodically excited. The instantaneous impulse responses are computed from the Captured Signal by taking the time-variance explicitly into account. In this paper, three different continuous measurement techniques are investigated and compared in a unified framework. It is shown that impulse response estimation constitutes a spatial interpolation process, where each method corresponds to a specific interpolation filter. In numerical simulations the performance of theses approaches are evaluated in terms of system distance and spatial bandwidth.

  • Continuous measurement of impulse responses on a circle using a uniformly moving microphone
    2015 23rd European Signal Processing Conference (EUSIPCO), 2015
    Co-Authors: Nara Hahn, Sascha Spors
    Abstract:

    We propose a continuous measurement technique which can be used to capture a large number of impulse responses within short time. The response of an acoustic system is continuously Captured by a moving microphone, and the instantaneous impulse responses are computed by post-processing. The time-variance due to the movement of the microphone is compensated by employing a recently proposed system identification method. In this method, each sample of the Captured Signal is interpreted as the orthogonal expansion coefficient of the instantaneous impulse response. The impulse responses are computed from the interpolated orthogonal coefficients. This method is applied to the measurement on a circle. Based on the modal bandwidth of the spatio-temporal impulse response, the relation among the length of the impulse response, the angular speed of the microphone, and the effective number of measurements is revealed. The presented measurement technique was used to measure a large number of room impulse responses, and the results were compared with a conventional sequential measurement technique.

Nara Hahn - One of the best experts on this subject based on the ideXlab platform.

  • Simultaneous Measurement of Spatial Room Impulse Responses from Multiple Sound Sources Using a Continuously Moving Microphone
    2018 26th European Signal Processing Conference (EUSIPCO), 2018
    Co-Authors: Nara Hahn, Sascha Spors
    Abstract:

    Continuous measurement techniques aim at identifying a large number of impulse responses from a Signal Captured by a moving microphone. In a recently proposed method, each sample of the Captured Signal is interpreted as a spatio-temporal sample of the sound field, and the individual impulse responses are computed by means of spatial interpolation. In the present study, the approach is extended towards multichannel cases. The superimposed sound field reproduced by multiple sources is recorded with one microphone, and the individual impulse responses are identified. To this end, the sound sources are excited with the same periodic perfect sequence, but a different amount of temporal shift is applied so that the identified impulse responses of different sources do not overlap. An anti-aliasing condition for the microphone speed is derived which is computed based on the spatial bandwidth of the sound field.

  • Continuous measurement of spatial room impulse responses using a non-uniformly moving microphone
    2017 IEEE Workshop on Applications of Signal Processing to Audio and Acoustics (WASPAA), 2017
    Co-Authors: Nara Hahn, Sascha Spors
    Abstract:

    The room impulse responses at multiple receiver positions can be measured efficiently with a continuously moving microphone. The acoustic system is periodically excited by a self-orthogonal Signal, called perfect sequence, and the microphone captures the sound field on a pre-defined path. As shown in recent studies by the authors, the Captured Signal constitutes a spatio-temporal sampling of the sound field, and the impulse responses can be obtained by a spatial interpolation. So far, a uniformly moving microphone was mainly considered for the measurement of spatial room impulse responses. In this paper, the method is applied to non-uniformly moving microphones thereby addressing more general cases. The proposed method is evaluated by numerical simulations where the spatial room impulse responses on a circle are measured using a microphone with a fluctuating angular speed. The accuracy of the impulse responses are compared for varying interpolation orders.

  • Comparison of continuous measurement techniques for spatial room impulse responses
    2016 24th European Signal Processing Conference (EUSIPCO), 2016
    Co-Authors: Nara Hahn, Sascha Spors
    Abstract:

    A large number of spatial room impulse responses can be measured efficiently by using a moving microphone in combination with a time-varying system identification method. The microphone moves on a predefined trajectory and captures the response of the acoustic system which is periodically excited. The instantaneous impulse responses are computed from the Captured Signal by taking the time-variance explicitly into account. In this paper, three different continuous measurement techniques are investigated and compared in a unified framework. It is shown that impulse response estimation constitutes a spatial interpolation process, where each method corresponds to a specific interpolation filter. In numerical simulations the performance of theses approaches are evaluated in terms of system distance and spatial bandwidth.

  • Continuous measurement of impulse responses on a circle using a uniformly moving microphone
    2015 23rd European Signal Processing Conference (EUSIPCO), 2015
    Co-Authors: Nara Hahn, Sascha Spors
    Abstract:

    We propose a continuous measurement technique which can be used to capture a large number of impulse responses within short time. The response of an acoustic system is continuously Captured by a moving microphone, and the instantaneous impulse responses are computed by post-processing. The time-variance due to the movement of the microphone is compensated by employing a recently proposed system identification method. In this method, each sample of the Captured Signal is interpreted as the orthogonal expansion coefficient of the instantaneous impulse response. The impulse responses are computed from the interpolated orthogonal coefficients. This method is applied to the measurement on a circle. Based on the modal bandwidth of the spatio-temporal impulse response, the relation among the length of the impulse response, the angular speed of the microphone, and the effective number of measurements is revealed. The presented measurement technique was used to measure a large number of room impulse responses, and the results were compared with a conventional sequential measurement technique.

Teymoor Ghanbari - One of the best experts on this subject based on the ideXlab platform.

  • Application of an Efficient Rogowski Coil Sensor for Switch Fault Diagnosis and Capacitor ESR Monitoring in Nonisolated Single-Switch DC–DC Converters
    IEEE Transactions on Power Electronics, 2017
    Co-Authors: Ebrahim Farjah, Hadi Givi, Teymoor Ghanbari
    Abstract:

    Power switches and electrolytic capacitors are the most vulnerable components in the power electronic converters. Any failure in these components may result in severe damages, if no remedial action is employed. Prior to any remedy, the first step is fault diagnosis. In this paper, a new type of Rogowski coil sensor is proposed. The sensor captures the inductor current derivative, which contains suitable signatures for switch fault diagnosis and capacitor lifetime monitoring in nonisolated single-switch dc-dc converters. Using the Captured Signal, detection of switch open-circuit and short-circuit faults is realized by a simple logic circuit. Furthermore, a new capacitor lifetime monitoring technique is proposed, which employs this Signal for calculating equivalent series resistance of the capacitor. The proposed sensor has some remarkable advantages. Due to its nonmagnetic core, the problem related to nonlinear response of magnetic cores at high frequencies will not be encountered. Furthermore, the proposed cost-efficient approach can be easily implemented even for already fabricated converters. The performance of the proposed sensor is evaluated using some finite-element simulations and experiments for a buck converter. The results confirm the capabilities of the sensor for switch fault diagnosis and capacitor lifetime monitoring in nonisolated single-switch dc-dc converters.

  • Switch fault diagnosis and capacitor lifetime monitoring technique for DC–DC converters using a single sensor
    IET Science Measurement & Technology, 2016
    Co-Authors: Hadi Givi, Ebrahim Farjah, Teymoor Ghanbari
    Abstract:

    Owing to the key role of the power electronic converters in various applications, their reliability is an important issue. The electrolytic capacitor and the power switch are the most vulnerable components of the converters. On fault occurrence in these components, a suitable remedial strategy should be employed to prevent further damages. The first step in any remedial strategy is fault diagnosis including fault detection and identification. This study proposes a technique for switch fault diagnosis and capacitor lifetime monitoring in non-isolated single-switch DC-DC converters. The proposed cost-effective method could be easily implemented using a printed circuit board Rogowski coil (PCBRC) on the capacitor terminals. The derivative of the capacitor current is Captured by the PCBRC. The Captured Signal contains suitable signatures for detection of switch open-circuit and short-circuit faults. In addition to switch fault detection, lifetime of the converter capacitor is also monitored by the PCBRC via calculation of the capacitor equivalent series resistance. The proposed technique is implemented for a buck converter. The experimental results confirm the capability of the proposed technique for switch fault diagnosis and capacitor lifetime monitoring in non-isolated single-switch DC-DC converters.

Ebrahim Farjah - One of the best experts on this subject based on the ideXlab platform.

  • Application of an Efficient Rogowski Coil Sensor for Switch Fault Diagnosis and Capacitor ESR Monitoring in Nonisolated Single-Switch DC–DC Converters
    IEEE Transactions on Power Electronics, 2017
    Co-Authors: Ebrahim Farjah, Hadi Givi, Teymoor Ghanbari
    Abstract:

    Power switches and electrolytic capacitors are the most vulnerable components in the power electronic converters. Any failure in these components may result in severe damages, if no remedial action is employed. Prior to any remedy, the first step is fault diagnosis. In this paper, a new type of Rogowski coil sensor is proposed. The sensor captures the inductor current derivative, which contains suitable signatures for switch fault diagnosis and capacitor lifetime monitoring in nonisolated single-switch dc-dc converters. Using the Captured Signal, detection of switch open-circuit and short-circuit faults is realized by a simple logic circuit. Furthermore, a new capacitor lifetime monitoring technique is proposed, which employs this Signal for calculating equivalent series resistance of the capacitor. The proposed sensor has some remarkable advantages. Due to its nonmagnetic core, the problem related to nonlinear response of magnetic cores at high frequencies will not be encountered. Furthermore, the proposed cost-efficient approach can be easily implemented even for already fabricated converters. The performance of the proposed sensor is evaluated using some finite-element simulations and experiments for a buck converter. The results confirm the capabilities of the sensor for switch fault diagnosis and capacitor lifetime monitoring in nonisolated single-switch dc-dc converters.

  • Switch fault diagnosis and capacitor lifetime monitoring technique for DC–DC converters using a single sensor
    IET Science Measurement & Technology, 2016
    Co-Authors: Hadi Givi, Ebrahim Farjah, Teymoor Ghanbari
    Abstract:

    Owing to the key role of the power electronic converters in various applications, their reliability is an important issue. The electrolytic capacitor and the power switch are the most vulnerable components of the converters. On fault occurrence in these components, a suitable remedial strategy should be employed to prevent further damages. The first step in any remedial strategy is fault diagnosis including fault detection and identification. This study proposes a technique for switch fault diagnosis and capacitor lifetime monitoring in non-isolated single-switch DC-DC converters. The proposed cost-effective method could be easily implemented using a printed circuit board Rogowski coil (PCBRC) on the capacitor terminals. The derivative of the capacitor current is Captured by the PCBRC. The Captured Signal contains suitable signatures for detection of switch open-circuit and short-circuit faults. In addition to switch fault detection, lifetime of the converter capacitor is also monitored by the PCBRC via calculation of the capacitor equivalent series resistance. The proposed technique is implemented for a buck converter. The experimental results confirm the capability of the proposed technique for switch fault diagnosis and capacitor lifetime monitoring in non-isolated single-switch DC-DC converters.

I. Borrego - One of the best experts on this subject based on the ideXlab platform.

  • An optimal technique for ECG noise reduction in real time applications
    2006 Computers in Cardiology, 2006
    Co-Authors: M. M. Elena, J. M. Quero, I. Borrego
    Abstract:

    This paper presents a novel and efficient algorithm of ECG compression in real time monitoring systems, updated with each new input Signal sample. This algorithm tries to improve the compression ratio of the Captured Signal by means of an optimal noise threshold in terms of hardware complexity and memory requirements. Threshold estimation is computed, using the instantaneous standard deviation, in order to decrease data sorting and storing resources, and allowing low-cost implementation in portable electronic systems. This method produces the highest number of null samples (more than 88.7%) using a low threshold and Signal errors with very acceptable merit figures (99.876% of EPE, and 0.193% of MSE). The quality of the recovered Signal is good for the clinical diagnosis, obtaining a superior compression rate in spite of using instantaneously Captured ECG Signals.