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         A3US – Research Interests and Applications          

The research envisaged at the A3US laboratory covers a broad spectrum of issues related to Signal Processing, Acoustics, Computed Imaging, Digital Communication and Image Processing . In the following, we will shortly describe the mainstreams of our research, from a methodological point of view, and the related application domains .

Array Signal Processing
A3US research is focused on spatial filtering aspects, which are at the basis of many advanced applications. In general we are interested in data-independent beamforming, data-dependent beamforming, near-field processing, wideband pulse beamforming, and broadband beamforming. Among our research activities, the following topics receive particular attention:
1. Stochastic methods for the synthesis of the lay-out and the weighting window of sparse planar arrays or, more in general, for the robust synthesis of any parameter affecting an array that should be optimized for a specific goal;
2. Beamforming algorithms in the frequency domain, characterized by a moderate computational burden, especially for 3-D real-time beamforming;
3. Synthesis methods to design a filter-&-sum beamforming structure with a robust, super-directive, and frequency-independent beam pattern.
4. Joint spectral and spatial processing to avoid or exploit harmonic signal components produced by nonlinear propagation or scattering.

Acoustical Imaging
We are interested in all the signal processing methods devoted to allow or improve the acoustical imaging (especially the array-based methods), in different application contexts, from synthetic aperture to sub-aperture processing. In particular, we address the following topics:
1. Array processing strategies for the 3-D, real-time, near-field, wideband acoustical imaging, and investigation of the related computational architecture.
2. Simulation of the signals acquired by a specific imaging system, for different scenarios and application contexts. This enables a cost-effective design of innovative and expensive imaging systems.
3. Methods to optimize all the signal and array parameters that make it possible to produce an acoustic beam with the desired characteristics, both in transmission and in reception, in terms of beam pattern, depth of field, pressure profile over distance, lateral resolution over distance etc.
4. Application of synthetic aperture and 3-D imaging concepts to improve the ultrasound non-destructive testing of mechanical parts.

Acoustic Signal & Image Processing

Research in this field is very spread, strictly depending on applications, and focused on underwater propagation modeling, advanced spectral analysis, jointly time-spectral analysis, reverberation and speckle reduction, underwater communication techniques, image enhancement and contrast equalization, image projection and interpolation (specially working on band-pass signals), signal detection and object detection, feature extraction and classification, 3-D image processing and segmentation, reconstruction of 3-D objects and augmented reality. In particular, we are developing:
1. Methods and tools for the underwater acoustic digital communication, including aspect of covertness, privacy, shallow-water multipath, dynamic Doppler shift, etc.
2. A signal processing framework for the detection, localization, and characterization of the ultrasound contrast agents (i.e., a micro-bubbles dispersion) used for medical diagnosis
3. A set of processing techniques for the improvement and the automatic analysis of the images produced by mechanically scanned high-frequency sonar systems
4. A simulation framework to investigate oceanogaphic micro-scale phenomena by means of advanced acoustic instrumentation


  Application Domains

Ultrasound medical imaging

with special emphasis on advanced and original methods for:
  • optimization of the array parameters (positions, weights, time-delays, frequencies, envelopes, etc.),
  • ultrasound contrast agent detection, characterization and imaging,
  • tissue harmonic imaging,
  • resolution, contrast and focusing improvement in medical scanners,
  • sparse array design,
  • 3-D real-time imaging ,
  • speckle reduction,
  • image interpolation and rendering.

Sonar systems

with special emphasis on advanced and original methods for:
  • performance estimation of active and passive sonar systems,
  • analysis of interferences and deployment problems
  • frequency-domain, dynamically-focused beamforming,
  • sparse array design,
  • 3-D real-time imaging systems,
  • analysis of the objects embedded in the seafloor,
  • ray-tracing for exact cell projection and image composition,
  • processing and analysis of 3-D images, 
  • interferometric bathymetry,
  • processing of high-frequency images and object tracking.

Underwater acoustics

with special emphasis on advanced and original methods for:
  • digital communication (covertness, privacy, shallow-water, etc.)
  • simulation of the signals received by a sonar array,
  • reduction of reverberation ,
  • signal detection, especially for the detection of objects embedded in the seafloor,
  • source localization,
  • oceanic tomography,
  • analysis of the informative content of underwater signals.

Microphone arrays

with special emphasis on advanced and original methods for:
  • broadband, passive, super-directive processing applied to advanced hearing aids
  • broadband, passive processing applied to speech processing and recognition systems
  • aerial acoustical imaging systems for robotic application

Non-destructive testing

with special emphasis on advanced and original methods for:
  • 2-D and 3-D imaging techniques based on the synthetic aperture concept.

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   last update: 26 March 2009