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Annual International Conference of the IEEE Engineering in Medicine and Biology Society

作者： Abdul Rauf Anwar Kidist Gebremariam Mideska Helge Hellriegel Nienke Hoogenboom Holger Krause Alfons Schnitzler Gunther Deuschl Jan Raethjen Ulrich Heute Muthuraman Muthuraman Faculty of Electrical Engineering Digital Signal Processing and System Theory University of Kiel Department of Neurology Universitatsklinikum Schleswig-Holstein Department of Neurology Heinrich-Heine University

ISBN: (纸本)9781424479276

Owing to the recent advances in multi-modal data analysis, the aim of the present study was to analyze the functional network of the brain which remained the same during the eyes-open (EO) and eyes-closed (EC) resting task. The simultaneously recorded electroencephalogram (EEG) and magnetoencephalogram (MEG) were used for this study, recorded from five distinct cortical regions of the brain. We focused on the 'alpha' functional network, corresponding to the individual peak frequency in the alpha band. The total data set of 120 seconds was divided into three segments of 18 seconds each, taken from start, middle, and end of the recording. This segmentation allowed us to analyze the evolution of the underlying functional network. The method of time-resolved partial directed coherence (tPDC) was used to assess the causality. This method allowed us to focus on the individual peak frequency in the 'alpha' band (7-13 Hz). Because of the significantly higher power in the recorded EEG in comparison to MEG, at the individual peak frequency of the alpha band, results rely only on EEG. The MEG was used only for comparison. Our results show that different regions of the brain start to 'disconnect' from one another over the course of time. The driving signals, along with the feedback signals between different cortical regions start to recede over time. This shows that, with the course of rest, brain regions reduce communication with each another.

关键词： Electroencephalography Brain models Mathematical model Time-frequency analysis Time series analysis Bidirectional control

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Method for temporal interpolation of short-term spectra and its application to adaptive system identification

Method for temporal interpolation of short-term spectra and ...

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International Conference on Acoustics, Speech, and signal processing (ICASSP)

作者： Mohamed Krini Gerhard Schmidt Acoustic Speech Enhancement Research Nuance Communications Aachen GmbH Ulm Germany Digital Signal Processing and System Theory Christian-Albrechts-Universität Kiel Kiel Germany

In this paper an extension of analysis filterbanks utilized in adaptive system identification schemes is presented. The extension operates as a postprocessing stage following conventional polyphase filterbanks or short-term Fourier transforms. The idea of the new method is to exploit the redundancy of succeeding short-term spectra for computing interpolated temporal supporting points. For its efficient implementation some approximations are performed - it can be shown that the postprocessing stage can be easily realized based on the weighted sum of subband signals. The new method allows for significant increase of the frameshift (subsampling rate), leading to a reduction of the computational complexity while keeping the convergence speed and the steady-state performance. Alternatively, the frameshift can be kept unchanged - in this case an improved steady-state convergence can be achieved. Real-time measurements performed with systems for acoustic echo cancellation have shown that significant improvements in terms of echo reduction can be achieved while increasing the amount of required memory only marginally.

关键词： Interpolation Echo cancellers Time frequency analysis Convergence Computational complexity Steady-state Speech

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Self-Tuning Active Sonar signal processing for a Towed Hydrophone Array during a Turn

Self-Tuning Active Sonar Signal Processing for a Towed Hydro...

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Oceans MTS/IEEE Washington (Conference)

作者： Kolja Pikora Frank Ehlers Digital Signal Processing and System Theory Faculty of Engineering University of Kiel Bundeswehr Technical Centre for Ships and Naval Weapons Naval Technology and Research Research Department for Underwater Acoustics and Marine Geophysics

ISBN: (纸本)9781467393744

This paper addresses the problem of hydrophone array shape estimation of a towed array system especially during maneuvers of the tow ship. Uncertainty in the position and velocity of each sensor of the array degrades the performance of a beamformer and, hence, leads to a loss of performance for the entire data processing chain, including target tracking and (if applicable) data fusion. A self-tuning approach is developed which uses information generated by automated target tracking during the period prior to the tow ship maneuver. This information is then used to perform a sequential tracking of the antenna system during the maneuver. The antenna tracking includes the estimation of the sensor positions which is implemented as a Gaussian sum filter. This approach allows to keep the handling of multi-target situations also during the turn. First results of validating the new approach in two simulated scenarios are presented, which indicate that the approach is capable of maintaining good tracking performance during the periods of tow ship maneuvers, whilst assuming only rough knowledge about the antenna in the beamforming leads to the expected performance loss. Tracking performance is expressed in terms of probability of detection and mean squared error of the target positions. For validation purposes, the sensitivity analysis of the new approach contains Monte Carlo (MC) selections of parameters describing both the tow ship maneuver and the multi-target setup.

关键词： Hydrophone arrays Active sonar Ships Data fusion Beamforming ANTENNA Target tracking visual tracking sensor placement sonar signal processing antennae Turning ANTENNA system

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A Concept for Myocardial Current Density Estimation with Magnetoelectric Sensors

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Current Directions in Biomedical Engineering 2023年第1期9卷 89-92页

作者： Schmidt, Gerhard Engelhardt, Erik Elzenheimer, Eric Hoffman, Johannes Schmidt, Tobias Zaman, Adrian Frey, Norbert Digital Signal Processing and System Theory Institute of Electrical Engineering and Information Technology Faculty of Engineering Kiel University Kaiserstr. 2 Kiel 24143 Germany Medical Department III Specialised in Cardiology and Angiology University Medical Center Schleswig-Holstein Arnold-Heller-Str. 3 / House K3 Kiel 24105 Germany Internal Medicine III: Heart Vascular and Lung University Medical Center Heidelberg Im Neuenheimer Feld 410 Heidelberg 69120 Germany

In this paper we present a novel noninvasive approach to estimate current densities in the heart from magnetocardiography. The proposed algorithm uses nested optimization to model current densities in equally-sized voxels of myocardial tissue. First-order Thiran all-pass filters are used to describe the propagation between *** demonstrate feasibility of the algorithm for a noise-free single-layer simulation. However, challenges remain, such as addressing measurement noise and optimizing propagation velocity. Overall, this approach has the potential to complement or replace invasive catheter-based electrophysiological studies for localization of arrhythmogenic tissue. © 2023 the author(s), published by Walter de Gruyter Berlin/Boston.

关键词： Magnetocardiography

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Reducing Computational Complexity of Gating Procedures Using Sorting Algorithms

Reducing Computational Complexity of Gating Procedures Using...

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International Conference on Information Fusion

作者： Viet Duc Nguyen Tim Claussen Digital Signal Processing and System Theory Christian-Albrechts-Universitat zu Kiel

ISBN: (纸本)9781479902842

Gating is an important part in many data association algorithms, specifically tracking algorithms. Its purpose is the preselection of suitable measurements or observations respectively in order to avoid unlikely measurement-to-track associations. As such, it can be essential for a low computational load. A very common gating method is individual ellipsoidal gating incorporating the Mahalanobis distance. On the one hand it is a reliable gating method used in many different tracking techniques, e.g., the global nearest neighbor method or the Multi-Hypothesis Tracking approach, but on the other hand it can be also very time consuming due to the inversions of covariance matrices related to all the measurement-to-track pairs. In this paper a Gating-by-Sorting approach is proposed to accelerate the gating procedure significantly. It uses sorting algorithms to carry out coarse gating followed by a second ellipsoidal gating step. The gating approach is incorporated into a multi-hypothesis tracker and applied to a real radar dataset. Results are obtained by measuring the computational load within tracking processes. They show that the proposed gating algorithm outperforms classical ellipsoidal gating by orders of magnitude.

关键词： Sorting algorithm complexity classes nearest neighbor algorithm Primary election data association Inversion tracking

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Adaptive Multi-mode Combination for Magnetoelectric Sensors Based on the Delta-E Effect

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Procedia Engineering 2015年 120卷 536-539页

作者： Jens Reermann Gerhard Schmidt Sebastian Zabel Franz Faupel Institute for Electrical and Information Engineering Chair for Digital Signal Processing and System Theory Kiel University Kaiserstraße 2 24143 Kiel Germany Institute for Materials Science Chair for Multicomponent Materials Kiel University Kaiserstraße 2 24143 Kiel Germany

Recently, magnetoelectric sensors have gained importance in medical applications. Among several sensor types microelectromechanical magnetic field sensors are a promising option since they can be manufactured in a very small fashion and can operate at room temperature. In this contribution we present a new readout scheme for such sensors that simultaneously uses amplitude and phase information of a multitude of mechanical modes of a single sensor. The sensors are based on the delta-E effect. All extracted information is optimally combined in order to get a sensor output signal with maximum signal-to-noise ratio (SNR). First measurements have shown very promising results.

关键词： signal Combination Biomagnetic Sensors delta-E Effect

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Comparison of Causality Analysis on Simultaneously Measured fMRI and NIRS signals during Motor Tasks

Comparison of Causality Analysis on Simultaneously Measured ...

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Annual International Conference of the IEEE Engineering in Medicine and Biology Society

作者： Abdul Rauf Anwar Makii Muthalib Stephane Perrey Andreas Galka Oliver Granert Stephan Wolff Guenther Deuschl Jan Raethjen Ulrich Heute Muthuraman Muthuraman Faculty of Digital Signal Processing and System theory University of Kiel Movement to Health (M2H) Euromov Montpellier-1 University Department of Neuropediatrics University of Kiel Department of Neurology University of Kiel Department of Neuroradiology University of Kiel

ISBN: (纸本)9781457702150

Brain activity can be measured using different modalities. Since most of the modalities tend to complement each other, it seems promising to measure them simultaneously. In to be presented research, the data recorded from Functional Magnetic Resonance Imaging (fMRI) and Near Infrared Spectroscopy (NIRS), simultaneously, are subjected to causality analysis using time-resolved partial directed coherence (tPDC). Time-resolved partial directed coherence uses the principle of state space modelling to estimate Multivariate Autoregressive (MVAR) coefficients. This method is useful to visualize both frequency and time dynamics of causality between the time series. Afterwards, causality results from different modalities are compared by estimating the Spearman correlation. In to be presented study, we used directionality vectors to analyze correlation, rather than actual signal vectors. Results show that causality analysis of the fMRI correlates more closely to causality results of oxy-NIRS as compared to deoxy-NIRS in case of a finger sequencing task. However, in case of simple finger tapping, no clear difference between oxy-fMRI and deoxy-fMRI correlation is identified.

关键词： fMRI brain activity NOC2L gene State space models

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The performance of the spatiotemporal Kalman filter and LORETA in seizure onset localization

The performance of the spatiotemporal Kalman filter and LORE...

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Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC)

作者： Laith Hamid Masoud Sarabi Natia Japaridze Gert Wiegand Ulrich Heute Ulrich Stephani Andreas Galka Michael Siniatchkin Department of Medical Psychology and Medical Sociology University of Kie1 Kiel Germany Department of Neuropediatrics University of Kiel Kie1 Germany Digital Signal Processing and System Theory University of Kiel Kie1 Germany

ISBN: (纸本)9781424492695

The assumption of spatial-smoothness is often used to solve the bioelectric inverse problem during electroencephalographic (EEG) source imaging, e.g., in low resolution electromagnetic tomography (LORETA). Since the EEG data show a temporal structure, the combination of the temporal-smoothness and the spatial-smoothness constraints may improve the solution of the EEG inverse problem. This study investigates the performance of the spatiotemporal Kalman filter (STKF) method, which is based on spatial and temporal smoothness, in the localization of a focal seizure's onset and compares its results to those of LORETA. The main finding of the study was that the STKF with an autoregressive model of order two significantly outperformed LORETA in the accuracy and consistency of the localization, provided that the source space consists of a whole-brain volumetric grid. In the future, these promising results will be confirmed using data from more patients and performing statistical analyses on the results. Furthermore, the effects of the temporal smoothness constraint will be studied using different types of focal seizures.

关键词： Electroencephalography Laplace equations Brain modeling Kalman filters Inverse problems Oscillators Magnetic resonance imaging

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Coherent source and connectivity analysis on simultaneously measured EEG and MEG data during isometric contraction

Coherent source and connectivity analysis on simultaneously ...

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Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC)

作者： M. Muthuraman H. Hellriegel N. Hoogenboom A. R. Anwar K. G. Mideksa H. Krause A. Schnitzler J. Raethjen G. Deuschl Department of Neurology Christian Albrecht's university Kiel Germany Department of Neurology Heinrich-Heine University Dusseldorf Germany Institute for Digital Signal Processing and System Theory Faculty of Engineering Christian Albrecht's university Kiel 24143 Germany

The most well-known non-invasive electric and magnetic field measurement modalities are the electroencephalography (EEG) and magnetoencephalography (MEG). The first aim of the study was to implement the recently developed realistic head model which uses an integrative approach for both the modalities. The second aim of this study was to find the network of coherent sources and the modes of interactions within this network during isometric contraction (ISC) at (15-30 Hz) in healthy subjects. The third aim was to test the effective connectivity revealed by both the modalities analyzing them separately and combined. The Welch periodogram method was used to estimate the coherence spectrum between the EEG and the electromyography (EMG) signals followed by the realistic head modelling and source analysis method dynamic imaging of coherent sources (DICS) to find the network of coherent sources at the individual peak frequency within the beta band in healthy subjects. The last step was to identify the effective connectivity between the identified sources using the renormalized partial directed coherence method. The cortical and sub-cortical network comprised of the primary sensory motor cortex (PSMC), secondary motor area (SMA), and the cerebellum (C). The cortical and sub-cortical network responsible for the isometric contraction was similar in both the modalities when analysing them separately and combined. The SNR was not significantly different between the two modalities separately and combined. However, the coherence values were significantly higher in the combined modality in comparison to each of the modality separately. The effective connectivity analysis revealed plausible additional connections in the combined modality analysis.

关键词： Electroencephalography Coherence Brain modeling Electromyography Electrodes Head Magnetic heads

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A Concept for Myocardial Current Density Estimation with Magnetoelectric Sensors

A Concept for Myocardial Current Density Estimation with Mag...

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作者： Schmidt, Gerhard Engelhardt, Erik Elzenheimer, Eric Hoffman, Johannes Schmidt, Tobias Zaman, Adrian Frey, Norbert Digital Signal Processing and System Theory Institute of Electrical Engineering and Information Technology Faculty of Engineering Kiel University Kaiserstr. 2 Kiel24143 Germany Medical Department III Specialised in Cardiology and Angiology University Medical Center Schleswig-Holstein Arnold-Heller-Str. 3 / House K3 Kiel24105 Germany Internal Medicine III: Heart Vascular and Lung University Medical Center Heidelberg Im Neuenheimer Feld 410 Heidelberg69120 Germany

关键词： Magnetocardiography

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