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  • 1.
    Bååth, Lars
    Halmstad University, School of Business and Engineering (SET), Mechanical Engineering and Industrial Design (MTEK), Fotonik.
    Functional surfaces2012Conference paper (Other academic)
  • 2.
    Bååth, Lars
    Halmstad University, School of Business and Engineering (SET), Mechanical Engineering and Industrial Design (MTEK), Fotonik.
    Fundamentals of Optical Measurement Systems: Part 1 - Fundamental of Optics2012Conference paper (Other academic)
  • 3.
    Bååth, Lars
    Halmstad University, School of Business and Engineering (SET), Mechanical Engineering and Industrial Design (MTEK), Fotonik.
    Fundamentals of Optical Measurement Systems: Part 2 - Measurement Systems2012Conference paper (Other academic)
  • 4.
    Bååth, Lars
    Halmstad University, School of Business, Engineering and Science, Mechanical Engineering and Industrial Design (MTEK), Fotonik.
    Noise Spectra from Wind Turbines2013In: Renewable energy, ISSN 0960-1481, E-ISSN 1879-0682, Vol. 57, p. 512-519Article in journal (Refereed)
    Abstract [en]

    This paper presents observations of audio noise in frequency range 20e20 000 Hz from wind turbines. The observations were performed around the theoretically calculated 40 dBA noise perimeter around the wind turbine farm at Oxhult, Sweden. This paper describes a newly designed and constructed a field qualified data acquisition system to measure spectra and total noise level of sound from wind turbines. The system has been calibrated at SP Borås. It is shown that it has a flat frequency response and is linear with amplitude and time.

    The total noise level (as integrated 20e20 000 Hz) is shown to be below 35 dBA (below the reference background noise at 36 dBA) at a 10 m altitude wind speed of 4e5 m/s. The measurements were made along the theoretical 40 dBA border at 8 m/s.

    It is concluded that the theoretical 40 dBA border seems reasonable calculated if the manufacturer specifications are used to extrapolate the sound level to correspond to 8 m/s at 10 m. Our data indicate that a simple sound propagation model is sufficient since the sound level is more affected by the nearby environment than the large scale forest structure. Also, the large scale forestry structure is bound to change with time and the error bars of measurements on total sound level are about 1 dBA, which is larger than any fine tuning with a more sophisticated model. More care should be taken to model the reflections from walls and other obstacles close to the microphones.

    The distribution of the spectral noise level around the turbine farm suggests that the noise originates from individual wind turbines closest to the measurement location rather than from the wind turbine farm as a whole. The spectra show narrow band spectral line features which do not contribute signifi-cantly to the total noise at this level. The narrow band features are only detectable at very long inte-gration time and at 1 Hz spectral resolution. The spectral features are typical to originate from mechanical noise.

    The spectral acquisition method described in this paper can be used as a field qualified system for sound measurements in forest areas. The high spectral resolution is a viable remote diagnostic method for mechanical faults in the turbine machinery. Future work will concentrate on these two areas.

  • 5.
    Bååth, Lars
    et al.
    Halmstad University, School of Business, Engineering and Science, Mechanical Engineering and Industrial Design (MTEK), Fotonik.
    Rosén, Bengt-Göran
    Halmstad University, School of Business, Engineering and Science, Mechanical Engineering and Industrial Design (MTEK), Functional Surfaces.
    Towards New Interferometer Technology for Surface Metrology2012In: Proceedings of the 12th International Conference of the European Society for Precision Engineering and Nanotechnology: June 4th - 7th [8th] 2012, Stockholm, Sweden. Vol. 1 / [ed] P. Shore, H. Spaan & T. Burke, Bedford: EUSPEN , 2012, Vol. 1, p. 158-161Conference paper (Refereed)
    Abstract [en]

    There is an increasing requirement from manufacturing industries for improved technologies to measure surface topography. New instruments have to be accurate; robust to be used on the industry floor; non-invasive; automatic; and sufficiently fast to be used in real time as well as to simultaneously measure over a large area. The industrial applications are plenty:

    • On-line quality control of machined parts,
    • Direct feed back to the manufacturing process,
    • Analysis and selection of surface texture/structure.

    This paper presents new developments in interferometer techniques for new robust area-based topographic instruments.

  • 6.
    Hashemzadeh, Parham
    Halmstad University, School of Business and Engineering (SET), Mechanical Engineering and Industrial Design (MTEK), Fotonik.
    Parametric Reconstruction of Objects Using Microwave Measurements2009Doctoral thesis, comprehensive summary (Other academic)
  • 7.
    Singaravelu, Praveen Kumar
    et al.
    Halmstad University, School of Business, Engineering and Science, Mechanical Engineering and Industrial Design (MTEK), Fotonik.
    Mohammad, Tawhidul Alam
    Halmstad University, School of Business, Engineering and Science, Mechanical Engineering and Industrial Design (MTEK), Fotonik.
    Electrical and Optical Characterization of InAsP/InP Nanowire-Based Avalanche Photodetectors2016Independent thesis Advanced level (degree of Master (One Year)), 40 credits / 60 HE creditsStudent thesis
    Abstract [en]

    The availability of new manufacturing methodology in solid state physics makes it possible to grow nano-photonic devices for better performance and unique properties. In this thesis work, we use I-V and FTIR spectroscopy to study the electrical and optical properties of InAsP/InP nanowire-based array avalanche photodetectors for near infrared applications. Measurements are performed at 300K and 5K for different applied biases under darkness and illumination conditions. I-V curves are plotted to understand the charge carrier transport in nanowire photodetectors and also to improve the device fabrication. I-V characteristics display non-optimal diode properties with large dark leakage currents. From spectrally resolved photocurrent measurements, peaks appear at photon energies of 1.34eV and 1.4eV respectively, corresponding to the bandgap of zinc blende (ZB) and wurtzite (WZ) InP. An additional photocurrent peak at 1.25eV agrees with the bandgap of the included InAsP segments. The Schottky-like contacts present at the top of the nanowires most likely generate additional photocurrent at higher photon energies. No breakdown effect is observed for the array devices. Complementary single-nanowire devices indicate an avalanche breakdown effect at  VR=-35V.

  • 8.
    Speich, M.
    et al.
    University Aalen, Aalen, Germany.
    Bååth, Lars
    Halmstad University, School of Business, Engineering and Science, Mechanical Engineering and Industrial Design (MTEK), Fotonik.
    Boerret, R.
    University Aalen, Aalen, Germany.
    Harrison, D.K.
    Glasgow Caledonian University, Glasgow, United Kingdom.
    Rosén, Bengt-Göran
    Halmstad University, School of Business, Engineering and Science, Mechanical Engineering and Industrial Design (MTEK), Functional Surfaces.
    Robot assisted steel polishing and surface characterisation2012In: Proceedings of the 12th International Conference of the European Society for Precision Engineering and Nanotechnology, EUSPEN 2012 / [ed] Spaan H., Burke T. & Shore P., Cranfield, Bedfordshire: euspen , 2012, Vol. 2, p. 205-208Conference paper (Refereed)
    Abstract [en]

    Polymer optics is a growing market both for medium quality optics and precision optics. Steel moulds for polymer optics are normally produced in several process steps; the last step before moulding is manual polishing. This step requires skilled experts and is very time-consuming. The focus of this paper is on robot polishing of steel moulds for polymer injection moulding of optics. The goal of this work is to replace manual polishing and other process steps with robot polishing. Therefore a new process has been developed to minimize the number of required process steps.

    Steel moulds for polymer optics demand high standards of roughness and shape accuracy. To reach the required specifications concerning roughness and shape accuracy different measurement and characterization methods are necessary. A combination of parameters determined with different measurement instruments is needed to validate the polishing results.

    This project was started by Aalen University and UVEX Safety Group together with the Experimental Ophthalmology Group Homburg/Saar. The goal for this new process is to produce a ready to use steel mould with a shape accuracy better than 4µm and a micro roughness of less than 5nm rms; with just one process step after grinding.

1 - 8 of 8
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