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Zeitschriftenartikel

  • E. Schwab
  • S. Pogrebnoj
  • M. Freund
  • Florian Flossmann
  • S. Vogl
  • K.-H. Frommolt

Automated bat call classification using deep convolutional neural networks

In: Bioacoustics - The International Journal of Animal Sound and its Recording pg. 1-16.

  • 18.03.2022 (2022)

DOI: 10.1080/09524622.2022.2050816

Identification of bats is most practically done by exploiting the characteristic features of their echolocation calls. This usually involves expert knowledge, expensive equipment and time-consuming post processing of previously recorded calls. Automated solutions exist, but are usually not as accurate as human experts. We present an automated solution for the processing of bat calls and identification of bat species with extremely high classification accuracy that can be used during live recording or in an automated post-processing software. Our algorithm is the first application of a Deep Convolutional Neural Network to classify bat species based on sound spectrogram images of their echolocation calls. We tested several deep CNN architectures including a modified Google Inception and a ResNet50 architecture. The nets were trained on a very large call database consisting of images of snippets of call spectrograms. All our software was developed in the Python programming language and an executable of the software is available on request.
  • Angewandte Naturwissenschaften und Wirtschaftsingenieurwesen
  • DIGITAL
Patent

  • W. Holzapfel
  • Florian Flossmann

Optische Positionsmessvorrichtung

Deutschland

  • (2011)
  • Angewandte Naturwissenschaften und Wirtschaftsingenieurwesen
Zeitschriftenartikel

  • Florian Flossmann
  • U. Schwarz
  • M. Maier
  • M. Dennis

Stokes parameters in the unfolding of an optical vortex through a birefringent crystal

In: Optics Express vol. 14 pg. 11402-11411.

  • (2006)
Following our earlier work (F. Flossmann et al., Phys. Rev. Lett. 95 253901 (2005)), we describe the fine polarization structure of a beam containing optical vortices propagating through a birefringent crystal, both experimentally and theoretically.We emphasize here the zero surfaces of the Stokes parameters in three-dimensional space, two transverse dimensions and the third corresponding to optical path length in the crystal. We find that the complicated network of polarization singularities reported earlier – lines of circular polarization (C lines) and surfaces of linear polarization (L surfaces) – can be understood naturally in terms of the zeros of the Stokes parameters.
  • Angewandte Naturwissenschaften und Wirtschaftsingenieurwesen
Hochschulschrift

  • Florian Flossmann

Singularitäten von Phase und Polarisation des Lichts

Universität Regensburg Regensburg Naturwissenschaftliche Fakultät II - Physik

  • 2006 (2006)
  • Angewandte Naturwissenschaften und Wirtschaftsingenieurwesen
Zeitschriftenartikel

  • Florian Flossmann
  • U. Schwarz
  • M. Maier

Propagation dynamics of optical vortices in Laguerre-Gaussian beams

In: Optics Communications vol. 250 pg. 218-230.

  • (2005)

DOI: 10.1016/j.optcom.2005.02.032

We have calculated the propagation dynamics of an initial off-axis vortex with topological charge 1 in Laguerre–Gaussian background beams View the MathML source(LG10andLG70), which are examples of background beams with non-generic dislocation surfaces, on which the real and imaginary parts of the light field are zero. When initially a vortex with broad core (e.g., r-vortex) is embedded in the background beam, the dislocation surfaces are destroyed during propagation and two vortices with opposite charge are created per dislocation surface in planes perpendicular to the propagation direction. For a vortex with narrow core (e.g., point vortex) diffraction is important and leads to the birth of more than two vortices per dislocation surface. These results are also valid for other background beams with dislocation surfaces, e.g., Hermite–Gaussian and Ince–Gaussian beams. We investigated experimentally the spatial evolution of the intensity distribution of an initial off-axis vortex with narrow core and topological charge 1 in View the MathML sourceLG10andLG70 background beams. The experimental results are in good agreement with the calculated intensity distributions.
  • Angewandte Naturwissenschaften und Wirtschaftsingenieurwesen
Zeitschriftenartikel

  • Florian Flossmann
  • U. Schwarz
  • M. Maier

Optical Vortices in a Laguerre-Gaussian LG10 beam

In: Journal of Modern Optics vol. 52

  • (2005)
  • Angewandte Naturwissenschaften und Wirtschaftsingenieurwesen