Monday, 16 April 2018 17:15

Flow-induced Noise in Hydroacoustic Sensor Systems

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Talker Dr. Jan Abshagen
Affiliation Wehrtechnische Dienststelle der Bundeswehr für Schiffe und Marinewaffen, Maritime Technologie und Forschung (WTD 71),
Kiel Germany
Date 16.04.2018
Time 17:15 h
Place Aquarium, Building D, Faculty of Engineering,
Kaiserstr. 2., 24143 Kiel

 

Abstract

Sound can propagate over a large distance in the sea without significant attenuation and is therefore of unique importance in underwater communication, navigation, and detection. Underwater sound is received in these applications with hydroacoustic sensor systems that are often attached to or towed behind a vessel. The turbulent flow that forms around the hull of the moving sensor system induces hydroacoustic noise in the interior that dominates the noise level (and therefore limits the performance) at larger speeds due to the strong speed dependence of flow acoustic sources (e.g. Lighthill’s v8-law). In a series of research cruises in recent years the statistical properties and underlying physical mechanisms of interior hydroacoustic noise induced from outer turbulent flows have been investigated under sea conditions with towed measurement systems. The talk will focus on the spatio-temporal correlation of the turbulent noise sources as well as the filter properties of the mechanical hull structure and the embedded hydrophones. The analysis is predominantly performed in wavenumber-frequency space. New developments in piezoelectric thin-film sensor technology allow in principle the design of specific wavenumber filters for flow noise reduction. The potential of such sensors for future underwater applications is discussed.

 

Short biography

Jan Abshagen is a research scientist in experimental and applied underwater acoustics at the Bundeswehr Technical Center for Ships and Naval Weapons, Maritime Technology and Research (WTD 71) in Kiel. He received his physics degree (Diplom) and his doctorate (Dr. rer. nat) from the University of Kiel in 1996 and 2000, respectively (Supervisor: Prof. G. Pfister, IEAP). From 2000 to 2001 he was a Research Associate at the Department of Physics and Astronomy, University of Manchester (UK), and from 2001 to 2005 at IFM-GEOMAR (SFB 460 Dynamics of Thermohaline Circulation Variability) in Kiel. After that he worked as a scientist in a research project (2005-07) funded by the Bundeswehr Research Institute for Underwater Acoustics and Marine Geophysics (FWG) in Kiel, before he became in 2008 a principal investigator on a DFG-funded temporary position at the Institute of Experimental and Applied Physics, University of Kiel. Later in 2008 he changed permanently to FWG and has worked since the integrating of FWG in 2009 at WTD 71. His research interests are in the area of hydroacoustics, vibroacoustics and flow acoustics, with a focus on flow induced noise in sensor systems, as well as in nonlinear dynamics in fluids and the transition to turbulence. He was the principal scientist in several research cruises.

Monday, 27 November 2017 17:15

Digital Road Noise Cancellation System Through Active Noise Control

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Talker Dr.-Ing. Vasudev Kandade Rajan
Affiliation Becker Automotive Systems GmbH,
Straubing, Germany
Date 27.11.2017
Time 17:15 h
Place Aquarium, Building D, Faculty of Engineering,
Kaiserstr. 2., 24143 Kiel

 

Abstract

The application of active noise cancellation in real-world has not been fully realized yet. From reducing environment noise through the usage of headphones, to engine noise on commercial jets there are a number of use cases. Each of these use case brings its own set of challenges which can be understood only through multi-disciplinary work. One such use case the the reduction of road noise in vehicles. Structure-borne road noise dominates the cabin of modern vehicles. Several road noise cancellation (RNC) prototype systems have been implemented and demonstrated. These systems are based mainly on analog sensors. The placement of these sensors has been so far been based on random optimization methods. In this talk I will talk about the challenges in developing a generic digital RNC system which includes problem analysis, sensor placement, and performance. An adaptive algorithm process the acceleration signals with high convergence and reaction time for various speed and surface ranges, in order to maintain high audible effects for the passengers. Several modern vehicle platforms are integrated with the digital RNC system with ANC microphone at the headliners and the standard audio loudspeaker setup in order to integrate the technology with the existing audio layout of the vehicle.

 

Short biography

Vasudev Kandade Rajan received Bachelors degree in Electronics and Communication from Visvesvaraya Technological University, Bangalore, India. He joined as Project Research Assistant in July 2008 in the Electrical Communication Engineering Dept, Indian Institute of Science, Bangalore. There he worked on performance management of IEEE 802.11 WLANs until Sept 2009. He then went to obtain his Masters degree (MSc.) in Digital Communications, 2011 and PhD degree in Signal Processing, 2017 from Universtiy of Kiel, Germany. Currently he is working in the R&D department of Harman Becker Automotive Systems GmbH, Straubing, Germany.

Monday, 20 November 2017 17:15

Artificial Bandwidth Extension using Deep Neural Networks

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Talker Jonas Sautter
Affiliation Nuance Communications,
Ulm, Germany
Date 20.11.2017
Time 17:15 h
Place Aquarium, Building D, Faculty of Engineering,
Kaiserstr. 2., 24143 Kiel

 

Abstract

In mobile communication, the bandwidth of transferred speech signals is either narrow-band (300Hz – 3.4kHz) or wide-band (50Hz – 7kHz or higher). As the limitation to 3.4kHz degrades the speech quality and intelligibility, it is of great interest to artificially extend narrow-band speech signals to wide-band speech.

This talk presents a deep neural network (DNN) approach to artificial bandwidth extension with a focus on robustness in practical applications.

It is based on the source-filter model which decomposes the signal into two parts:

  • an excitation signal and
  • a spectral envelope.

The excitation (source part) describes the fine spectral structure which consists of white noise for unvoiced speech and an impulse train for voiced speech. The spectral envelope (filter part) describes the coarse spectral structure, i.e. the formants or resonance frequencies that make up different phonemes.

While the extension of the excitation signal can be done with simple mathematical methods that do not introduce strong artifacts, the envelope is much more relevant for the quality of the reconstructed wide-band signal. That is why the wide-band envelope is estimated with DNNs in this approach, which are trained on a large speech corpus.

 

Short biography

Jonas Sautter studied Electrical Engineering, Information Technology and Computer Engineering at RWTH Aachen University, Germany. He received his Master of Science degree in 2016. The Master’s thesis with the title “Digital Robust Control for Active Noise Cancellation in Headphones and Hearing Aids” was composed at the Institute of Communication Systems at RWTH Aachen. Since November 2016, he is a PhD student at Nuance Communications in Ulm, supervised by Professor Gerhard Schmidt, Head of the Digital Signal Processing and System Theory group at Christian-Albrechts-Universität, Kiel.

Thursday, 14 September 2017 17:00

Physiology of Peripheral Nerve Conduction from a Signal Analysis Point of View

Details    
Talker Prof. Dr. med. Wilhelm Schulte-Mattler
Affiliation Neurologische Klinik und Poliklinik,
Universität Regensburg
Date 14.09.2017
Time 17:00 h
Place Aquarium, Building D, Faculty of Engineering,
Kaiserstr. 2., 24143 Kiel

 

German title

Physiologie peripherer Nerven aus Sicht der Signalverarbeitung

 

Abstract

To transmit information, peripheral nerve fibers locally change their electrical membrane properties. The changed regions move along the fibers causing traveling electrical fields, causing changes in voltage over time that depend both on where the voltage is recorded and on the nerve’s properties. Things are complicated by the nerves being composed of many thousands of fibers.

A simple model that explains these voltage changes, namely the signals that are recorded from actively transmitting nerves, will be presented. These signals provide information about the nerve’s function. Both, the influence of the recording conditions and the influence of various nerve disorders on the recorded waveforms will be presented. The usefulness of simple measures, such as amplitude and duration, is established. More advanced signal analysis indeed provides more information about peripheral nerve disorders.

 

Short biography

Wilhelm Schulte-Mattler studied Mathematics and Physics, followed by Medicine. He graduated at the University of Würzburg in 1988. His thesis was on Quantification of recruitment in needle-EMG. He specialized in Neurology in 1993. After heading Clinical Neurophysiology in the Dept. of Neurology, University of Halle-Wittenberg; since the year 2000, he is head of Clinical Neurophysiology in the Dept. of Neurology, University of Regensburg. A significant part of his work is on waveform analysis in clinical neurophysiology, particularly in electromyography and in electroneurography.