Remote Temperature Monitoring in Furnaces and Boilers

Remote Temperature Monitoring in Furnaces and Boilers

Remote Temperature Monitoring in Furnaces and Boilers Temperature changes influence the speed of sound Harsh environment – low SNR High temperature gradient – use bent rays for modeling sound propagation Solve non-linear optimization Temperature monitoring inside furnace Projects3D automated whole breast ultrasound imaging Improved focusing in HIFU and SWL 3D automatic breast boundary detection Beamforming in acoustic tomography Ultrasound tomography with learned dictionaries Ultrasound tomography for breast screening Remote Temperature Monitoring in Furnaces and Boilers Temperature and flow estimation in the atmosphere Compact loudspeaker arrays for directional sound reproduction Automatic multi-channel room acoustics correction Sound field rendering ⇦ ALL PROJECTS Interested in working together? We are currently looking for partners that will actively support our development. Contact...
Temperature and flow estimation in the atmosphere

Temperature and flow estimation in the atmosphere

Temperature and flow estimation in the atmosphere Overview Sound propagation in the atmosphere is strongly influenced by temperature and wind, and, therefore, it can be used to measure these physical phenomena. It is also important that the atmosphere is very transparent to low frequency sound, so that the acoustic signal can be transmitted over distances of several hundred meters with low attenuation. The advantage of tomography methods to provide a number of measurements proportional to the square of the number of sensors, can be well used to obtain high resolution reconstructions of temperature and wind fields. It then can be particularly useful for the study of small scale temperature variations and wind turbulences. In the atmosphere, the transmitted signal has low frequency, that ranges from 100 Hz for the distances of few hundreds meters to 50 KHz for the distances up to ten meters. To be able to sample this signal without any aliasing, we need a sampling card that works at a frequency only twice higher that the maximal frequency of our signal. Hence, an accurate time-of-flight estimation can be achieved without using expensive and fast audio acquisition cards (A/D convertors). Experimental Setup The setup consists of 12 emitters and 12 receivers placed on a 1 m radius ring. Piezoelectric transducers are used to send and receive the acoustic signal.  The emitters are equipped with amplifiers, and the receivers with preamplifiers, in order to guarantee the signal levels compatible with the audio card (Motu 24I/O card). This card is used to interface the transmitted and the acquired signals with a personal computer. To suppress the sound reflections the ring is covered with a foam. Time of flight estimation...
Compact loudspeaker arrays for directional sound reproduction

Compact loudspeaker arrays for directional sound reproduction

Compact loudspeaker arrays for directional sound reproduction Loudspeakers and loudspeaker arrays that reproduce sound highly directionally are interesting in a variety of applications, such as generating spatial effects and ambience, mitigating the room effects, or directional sound reproduction for public address systems and teleconferencing terminals. Our loudspeaker array is a result of combining signal processing and acoustical design. Its directional reproduction is highly consistent over a wide range of frequencies and without noticeable coloration. Additionally, thanks to the loudspeaker arrangement, reproduced sound can be steered towards multiple directions, which comes in handy for targeted sound reproduction and multichannel sound reproduction in rooms. Related publications M. Kolundzija, “Spatial acoustic signal processing,” PhD Thesis, 2012. [Bibtex] @phdthesis{kolundzijaspatial, title={Spatial Acoustic Signal Processing}, author={Kolundzija, Mihailo}, year={2012}, school={PhD thesis, {EPFL}, Lausanne, Switzerland} } M. Kolundzija, C. Faller, and M. Vetterli, “Design of a compact cylindrical loudspeaker array for spatial sound reproduction,” in Audio Engineering Society Convention 130, 2011. [Bibtex] @inproceedings{kolundzija2011design, title={Design of a Compact Cylindrical Loudspeaker Array for Spatial Sound Reproduction}, author={Kolundzija, Mihailo and Faller, Christof and Vetterli, Martin}, booktitle={{A}udio {E}ngineering {S}ociety {C}onvention 130}, year={2011}, organization={Audio Engineering Society} } M. Kolundzija, C. Faller, and M. Vetterli, “Baffled circular loudspeaker array with broadband high directivity,” in Acoustics Speech and Signal Processing (ICASSP), 2010 IEEE International Conference on, 2010, pp. 73-76. [Bibtex] @inproceedings{kolundzija2010baffled, title={Baffled circular loudspeaker array with broadband high directivity}, author={Kolundzija, Mihailo and Faller, Christof and Vetterli, Martin}, booktitle={{A}coustics {S}peech and {S}ignal {P}rocessing ({ICASSP}), 2010 {IEEE} {I}nternational {C}onference on}, pages={73--76}, year={2010}, organization={IEEE} } Projects3D automated whole breast ultrasound imaging Improved focusing in HIFU and SWL 3D automatic breast boundary detection Beamforming in acoustic tomography Ultrasound...
Automatic multi-channel room acoustics correction

Automatic multi-channel room acoustics correction

Automatic multi-channel room acoustics correction We developed a low-frequency automatic room acoustics correction approach for single- and multi-channel sound reproduction setups. Our approach alleviates the variability of the room impulse response in a wide listening area, while automatically detecting and mitigating the effects of strong resonances. The room correction filters are optimized in order to avoid the problems such as loudspeaker frequency distortions, sound localization bias, and temporal distortions in the form of pre- and post-echoes. Related publications M. Kolundzija, “Spatial acoustic signal processing,” PhD Thesis, 2012. [Bibtex] @phdthesis{kolundzijaspatial, title={Spatial Acoustic Signal Processing}, author={Kolundzija, Mihailo}, year={2012}, school={PhD thesis, {EPFL}, Lausanne, Switzerland} } M. Kolundzija, C. Faller, and M. Vetterli, “Multi-channel low-frequency room equalization using perceptually motivated constrained optimization,” in Acoustics, Speech and Signal processing (ICASSP), 2012 IEEE international conference on, 2012, pp. 533-536. [Bibtex] @inproceedings{kolundzija2012multi, title={Multi-channel low-frequency room equalization using perceptually motivated constrained optimization}, author={Kolundzija, Mihailo and Faller, Christof and Vetterli, Martin}, booktitle={{A}coustics, {S}peech and {S}ignal Processing ({ICASSP}), 2012 {IEEE} International Conference on}, pages={533--536}, year={2012}, organization={IEEE} } Projects3D automated whole breast ultrasound imaging Improved focusing in HIFU and SWL 3D automatic breast boundary detection Beamforming in acoustic tomography Ultrasound tomography with learned dictionaries Ultrasound tomography for breast screening Remote Temperature Monitoring in Furnaces and Boilers Temperature and flow estimation in the atmosphere Compact loudspeaker arrays for directional sound reproduction Automatic multi-channel room acoustics correction Sound field rendering ⇦ ALL PROJECTS Interested in working together? We are currently looking for partners that will actively support our development. Contact...
Sound field rendering

Sound field rendering

Sound field rendering Given a large number of transducers, one can attempt to reproduce a desired sound field in a domain of interest. This is of particular interest in sound reproduction for a big audience, where one desires an auditory experience independent of the listening spot. We developed an approach for optimal sound field reconstruction in an extended continuous listening space using an array of transducers. The technique is general and flexible, capable of automatically accounting for the propagation characteristics of the medium, and the directivity of the used transducers and reproduced sound sources. Related publications M. Kolundzija, “Spatial acoustic signal processing,” PhD Thesis, 2012. [Bibtex] @phdthesis{kolundzijaspatial, title={Spatial Acoustic Signal Processing}, author={Kolundzija, Mihailo}, year={2012}, school={PhD thesis, {EPFL}, Lausanne, Switzerland} } M. Kolundzija, C. Faller, and M. Vetterli, “Reproducing sound fields using MIMO acoustic channel inversion,” Journal of the Audio Engineering Society, vol. 59, iss. 10, pp. 721-734, 2011. [Bibtex] @article{kolundzija2011reproducingsoundfields, title={Reproducing sound fields using {MIMO} acoustic channel inversion}, author={Kolundzija, Mihailo and Faller, Christof and Vetterli, Martin}, journal={Journal of the {A}udio {E}ngineering {S}ociety}, volume={59}, number={10}, pages={721--734}, year={2011}, publisher={Audio Engineering Society} } M. Kolundzija, C. Faller, and M. Vetterli, “Designing practical filters for sound field reconstruction,” in Audio Engineering Society Convention 127, 2009. [Bibtex] @inproceedings{kolundzija2009designing, title={Designing Practical Filters For Sound Field Reconstruction}, author={Kolundzija, Mihailo and Faller, Christof and Vetterli, Martin}, booktitle={{A}udio {E}ngineering {S}ociety {C}onvention 127}, year={2009}, organization={Audio Engineering Society} } M. Kolundzija, C. Faller, and M. Vetterli, “Sound field reconstruction: an improved approach for wave field synthesis,” in Audio Engineering Society Convention 126, 2009. [Bibtex] @inproceedings{kolundzija2009sound, title={Sound field reconstruction: An improved approach for wave field synthesis}, author={Kolundzija, Mihailo and Faller, Christof...