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  • 1.
    Akujor, Chidi E.
    et al.
    Onsala Space Observatory, Chalmers University of Technology, Gothenburg, Sweden.
    Bååth, L.B.
    Onsala Space Observatory, Chalmers University of Technology, Gothenburg, Sweden.
    Combined-Array Imaging of Extra-Galactic Radio Sources1994In: Astronomy with Millimeter and Submillimeter Wave Interferometry: IAU Colloquium 140 : Meeting held 5-9 October 1992, Hakone, Japan / [ed] M. Ishiguro & Wm. J. Welch, San Francisco: Astronomical Society of the Pacific , 1994, p. 123-124Conference paper (Refereed)
  • 2.
    Alberdi, A.
    et al.
    Laboratorio de Astrofísica Espacial y Física Fundamental, Madrid, Spain; Instituto de Astrofísica de Andalucía CSIC, Granada, Spain.
    Krichbaum, T.P.
    Max Planck Institut für Radioastronomie, Bonn, Germany.
    Graham, D.A.
    Max Planck Institut für Radioastronomie, Bonn, Germany.
    Greve, A.
    IRAM, Domaine Universitaire, Grenoble, France.
    Grewing, M.
    IRAM, Domaine Universitaire, Grenoble, France.
    Marcaide, J.M.
    Departamento de Astronomía Universitat de Valéncia, Spain.
    Booth, R.S.
    Onsala Space Observatory.
    Bååth, Lars B.
    Onsala Space Observatory.
    Colomer, F.
    Onsala Space Observatory; Observatorio de Yebes, Guadalajara, Spain.
    Doeleman, S.
    NEROC, Haystack Observatory, Westford, Massachusetts, USA.
    Marscher, A.P.
    Boston University, Boston, MA, USA.
    Rogers, A.E.E.
    NEROC, Haystack Observatory, Westford, Massachusetts, USA.
    Schalinski, C.J.
    IRAM, Domaine Universitaire, Grenoble, France; Institut für Weltraumsensorik (DLR), Berlin, Germany.
    Standke, K.
    Max Planck Institut für Radioastronomie, Bonn, Germany.
    The high-frequency compact radio structure of the peculiar quasar 4C 39.251997In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 327, no 2, p. 513-521Article in journal (Refereed)
    Abstract [en]

    We present new high angular resolution images of the compact non-thermal radio source 4C 39.25 obtained from VLBI observations at λ1.3cm, λ7mm, and λ3mm wavelengths. These maps and Gaussian model-fits show that the milli-arcsecond to sub-milliarcsecond structure of 4C 39.25 consists of a complex bent core-jet structure with embedded moving and stationary VLBI components. Facilitated by the small observing beams and high angular resolutions obtained at mm-wavelengths, we measured the relative positions of the jet components with an accuracy of a few hundred micro-arcseconds. This allows the detailed followup of the ongoing merging process of a westward superluminally moving component (b_) with a stationary component a_, located at ~2.9 mas east of the putative core d_. In contrast to the other components of the structure with steeper spectra, the westernmost component d_ exhibits an inverted spectrum peaking between λ7mm and λ3mm, thus further supporting its identification as the VLBI core, self-absorbed at longer wavelengths. From two VLBI maps obtained nearly simultaneously at λ7mm and λ1.3cm, we made the first spectral index map of 4C 39.25 in this wavelength regime. The main characteristics of the spectral index distribution of the jet are pronounced changes of the spectral index between orientations parallel and transverse to the jet axis. Near the merging components a_ and b_ the spectral index steepens with increasing separation from d_. However, in the bridge of emission c_, which connects d_ with a_ and b_, the spectral index gradient has a direction transverse to the jet axis, suggesting a frequency dependent jet curvature and edge-brightening. A brief discussion of this behaviour within current jet models is presented.

  • 3.
    Bartel, N.
    et al.
    Department of Earth and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA; Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA & Harvard-Smithsonian Astrophysical Observatory, Cambridge, MA, USA.
    Shapiro, I.I.
    Department of Earth and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA; Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA & Harvard-Smithsonian Astrophysical Observatory, Cambridge, MA, USA.
    Corey, B.E.
    NEROC, Haystack Observatory, Westford, MA, USA.
    Marcaide, J.M.
    Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA & Max-Planck-Institut für Radioastronomie, Bonn, Germany.
    Rogers, A.E.E.
    NEROC, Haystack Observatory, Westford, MA, USA.
    Whitney, A.R.
    NEROC, Haystack Observatory, Westford, MA, USA.
    Cappallo, R.J.
    NEROC, Haystack Observatory, Westford, MA, USA.
    Kühr, H.
    Steward Observatory, Tucson, AZ, USA.
    Graham, D.
    Max-Planck-Institut für Radioastronomie, Bonn, Germany.
    Bååth, L.B.
    Onsala Space Observatory, Chalmers University of Technology, Gothenburg, Sweden.
    The Compact Radio Source 2021+614: Simultaneous 2.3 and 8.3 GHz Mark III VLBI Observations1984In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 279, no 1, p. 116-121Article in journal (Refereed)
    Abstract [en]

    Second-epoch VLBI observations of the flat-spectrum radio source 2021+614 made simultaneously at 2.3 and 8.3 GHz with the Mark III system are reported. The maps derived from these observations reveal a complex, frequency-dependent radio structure on the milliarcsecond scale. The object has four nearly collinear components oriented at a position angle of about 35 degrees and embedded in an extended region. Two of these are optically thin, one has a flat spectrum, and the other appears to be synchrotron self-absorbed in the frequency range 2.3-8.3 GHz. No significant structural variation is found at either frequency between epochs separated by about three years. The formal estimate of the transverse velocity between two components, one with a flat and the other with an inverted spectrum, is v/c = 0.7 + or - 2.3. Remarkable similarities between 2021+614 and the unusual source 0316+413 are discussed.

  • 4.
    Booth, R. S.
    et al.
    University of Manchester, Nuffield Radio Astronomy Laboratories, Jodrell Bank, Cheshire, United Kingdom.
    Spencer, R. E.
    University of Manchester, Nuffield Radio Astronomy Laboratories, Jodrell Bank, Cheshire, United Kingdom.
    Stannard, D.
    University of Manchester, Nuffield Radio Astronomy Laboratories, Jodrell Bank, Cheshire, United Kingdom.
    Bååth, L.B.
    Onsala Space Observatory, Chalmers University of Technology, Gothenburg, Sweden.
    High-resolution observations of quasars from the Parkes +/- 4 deg. sample1979In: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 188, p. 159-163Article in journal (Refereed)
    Abstract [en]

    VLBI observations of 20 compact quasars have been made between Jodrell Bank and Onsala at a frequency of 1666 MHz. Twelve of the quasars have inverted or peaked spectra at centimetre wavelengths and these are all unresolved, having angular diameters of less than 0.015 arcsec. Two out of five quasars with overall flat spectra are partially resolved on this scale size, as are three steep-spectrum quasars.

  • 5.
    Borkowski, Kazimierz M.
    et al.
    Toruń Radio Astronomy Observatory, Nicolaus Copernicus University, Toruń, Poland.
    Bååth, L.B.
    Onsala Space Observatory, Chalmers University of Technology, Gothenburg, Sweden.
    Determination of the Toruń Antenna Position from VLBI Observations1992In: Acta Astronomica, ISSN 0001-5237, Vol. 42, p. 371-375Article in journal (Refereed)
    Abstract [en]

    Four strong radio sources were observed over a 12-hr session in March, 1990 between radio telescopes at Onsala and Torun at wavelength of 6 cm in the standard VLBI Mark II setup for the purpose of improving the coordinates of the Torun 15-meter antenna. The Cartesian coordinates of the antenna derived from the presented measurements are (in meters): 3638609.62 +/- 0.19, 1221773.23 +/- 0.54 and 5077024.50 +/- 1.66 in the x, y, and z directions, respectively.

  • 6.
    Bååth, Lars
    Halmstad University, School of Business and Engineering (SET), Mechanical Engineering and Industrial Design (MTEK).
    A method for measuring temperature, molecular composition or molecular densities in gases1994Patent (Other (popular science, discussion, etc.))
  • 7.
    Bååth, Lars
    Halmstad University, School of Business and Engineering (SET), Mechanical Engineering and Industrial Design (MTEK).
    A method for simultaneously measuring the positions of more than one surface in metallurgic processes1994Patent (Other (popular science, discussion, etc.))
  • 8.
    Bååth, Lars
    Halmstad University, School of Business and Engineering (SET), Mechanical Engineering and Industrial Design (MTEK).
    A method to simultaneously measuring the position of more than one surface in metallurgical processes1997Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    A method for measuring the position of at least one surface in a metallurgical process which includes the steps of providing a metallurgical melt, the metallurgical melt including at least a metal portion and a slag layer, providing a signal generator for generating signals at a plurality of frequencies over a frequency band, and providing an antenna for receiving the signals generated by the signal generator and for transmitting circularly polarized radio waves at the plurality of frequencies over the frequency band. The invention further includes the steps of disposing the antenna adjacent the metallurgical melt, transmitting the circularly polarized radio waves from the antenna toward the metallurgical melt, the circularly polarized radio waves being transmitted by the antenna at the plurality of frequencies over the frequency band, receiving reflected images of the transmitted radio waves through the antenna, the received reflected images of the transmitted radio waves having a substantially opposite circular polarization from the transmitted circularly polarized radio waves, determining a phase displacement between the transmitted radio waves and the received reflected images of the transmitted radio waves, transforming the determined phase displacement from a frequency to a time plane, and determining from the time plane transform a position of at least one surface of at least one of the metal portion and the slag layer.

  • 9.
    Bååth, Lars
    Halmstad University, School of Business and Engineering (SET), Mechanical Engineering and Industrial Design (MTEK), Fotonik.
    Functional surfaces2012Conference paper (Other academic)
  • 10.
    Bååth, Lars
    Halmstad University, School of Business and Engineering (SET), Mechanical Engineering and Industrial Design (MTEK).
    Functional surfaces2011Conference paper (Other academic)
  • 11.
    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)
  • 12.
    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)
  • 13.
    Bååth, Lars
    Halmstad University, School of Business and Engineering (SET), Mechanical Engineering and Industrial Design (MTEK).
    Mathod for measuring temperature, molecular composition or molecular densities in gases2001Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    A measuring technique and method are provided to simultaneously determine the molecular density of several molecular species and the temperature within a closed process room in a melting or combustion process. In such processes in the industry, e.g. in metallurgic process industry, it is important to determine the temperature and the contents within the gas or flame without physically connect to or disturb the process. This has shown to raise large problems especially at high temperatures. The radio signal over a frequency band is measured on the outside of the process room through a window in the mantel covering as a function of frequency and registered on a computer as a radio spectrum. The system is calibrated by using a known signal transmitted through the process room. The spectral lines are identified by their frequency from a database. The temperature is determined from several lines of the same molecular specie and the molecular densities are determined from the intensities of the lines. The method is suitable to determine vibrational and rotational excitation of molecular species in the radio wavelength range of 30 micrometers to 500 meters. The densities of molecular species and the temperature can be imaged in three dimensions inside the process room or exhaust channel if interferometers are used for simultaneous two dimensional imaging from several azimuth directions.

  • 14.
    Bååth, Lars
    Halmstad University, School of Business and Engineering (SET), Mechanical Engineering and Industrial Design (MTEK), Fotonik och mikrovågsteknik.
    Method and device for contact level and interface detection2009Patent (Other (popular science, discussion, etc.))
  • 15.
    Bååth, Lars
    Halmstad University, School of Business and Engineering (SET), Mechanical Engineering and Industrial Design (MTEK), Fotonik och mikrovågsteknik.
    Method for analysing a substance in a container2008Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    Method and apparatus for analysing a substance in a container, the method comprising the steps of: disposing antenna means (3) at a predetermined geometrical distance (L) from a container portion (13); transmitting a signal from said antenna means through a surface portion (12) of the substance towards said container portion; receiving a first reflected signal in said antenna means from said container portion; determining a geometrical distance (L 1 ) from the surface portion to the container portion; varying the frequency of the transmitted signal to determine a first phase displacement between the transmitted signal and the first reflected signal; determining an optical distance from the surface portion to the container portion based on the first phase displacement; and determining the index of refraction (n 1 ) of said substance based on the optical and geometrical from the surface portion to the container portion.

  • 16.
    Bååth, Lars
    Halmstad University, School of Business and Engineering (SET), Mechanical Engineering and Industrial Design (MTEK).
    Method for measuring molecular composition or molecular densities in gases2000Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    A measuring technique and method are provided to simultaneously determine the molecular density of several molecular species and the temperature within a closed process room in a melting or combustion process. In such processes in the industry, e.g. in metallurgic process industry, it is important to determine the temperature and the contents within the gas or flame without physically connect to or disturb the process. This has shown to raise large problems especially at high temperatures. The radio signal over a frequency band is measured on the outside of the process room through a window in the mantel covering as a function of frequency and registered on a computer as a radio spectrum. The system is calibrated by using a known signal transmitted through the process room. The spectral lines are identified by their frequency from a database. The temperature is determined from several lines of the same molecular specie and the molecular densities are determined from the intensities of the lines. The method is suitable to determine vibrational and rotational excitation of molecular species in the radio wavelength range of 30.mu.m to 500 m. The densities of molecular species and the temperature can be imaged in three dimensions inside the process room or exhaust channel if interferometers are used for simultaneous two dimensional imaging from several azimuth directions.

  • 17.
    Bååth, Lars
    Halmstad University, School of Business and Engineering (SET), Mechanical Engineering and Industrial Design (MTEK).
    Method for measuring temperature of at least one of gas and a flame in a combustion process1998Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    A measuring technique and method are provided to simultaneously determine the molecular density of several molecular species and the temperature within a closed process room in a melting or combustion process. In such processes in the industry, e.g. in metallurgic process industry, it is important to determine the temperature and the contents within the gas or flame without physically connect to or disturb the process. This has shown to raise large problems especially at high temperatures. The radio signal over a frequency band is measured on the outside of the process room through a window in the mantel covering as a function of frequency and registered on a computer as a radio spectrum. The system is calibrated by using a known signal transmitted through the process room. The spectral lines are identified by their frequency from a database. The temperature is determined from several lines of the same molecular specie and the molecular densities are determined from the intensities of the lines. The method is suitable to determine vibrational and rotational excitation of molecular species in the radio wavelength range of 500 m et 30 m. The densities of molecular species and the temperature can be imaged in three dimensions inside the process room or exhaust channel if interferometers are used for simultaneous two dimensional imaging from several azimuth directions.

  • 18.
    Bååth, Lars
    Halmstad University, School of Business and Engineering (SET), Mechanical Engineering and Industrial Design (MTEK).
    Multi-dimensional imaging method and apparatus2007Patent (Other (popular science, discussion, etc.))
  • 19.
    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.

  • 20.
    Bååth, Lars
    Halmstad University, School of Business and Engineering (SET), Mechanical Engineering and Industrial Design (MTEK), Fotonik och mikrovågsteknik.
    Position measuring system2003Patent (Other (popular science, discussion, etc.))
  • 21.
    Bååth, Lars
    Halmstad University, School of Business, Engineering and Science, Mechanical Engineering and Industrial Design (MTEK).
    To See What You Cannot See2003In: Image Analysis: 13th Scandinavian Conference, SCIA 2003, Halmstad, Sweden, June 29 - July 2, 2003, Proceeding / [ed] Josef Bigun, Tomas Gustavsson, Heidelberg: Springer Verlag , 2003, p. 108-108Chapter in book (Other (popular science, discussion, etc.))
    Abstract [en]

    This paper discusses imaging with complex data from micro-wave, mm-wave, and optical interferometers. An overview of methods to extract physical parameters as images from interferometer data is made and two- and three-dimensional images of gas flows, quasi-stellar objects, steel melts, and fiber material such as wood are presented.

  • 22.
    Bååth, Lars B.
    Halmstad University, School of Business and Engineering (SET).
    3-dimensional imaging of refractory material at Pilkington Halmstad1996Report (Refereed)
  • 23.
    Bååth, Lars B.
    Halmstad University, School of Business and Engineering (SET).
    Analys av avgaser med mikrovågspektroskopi2004Report (Refereed)
    Abstract [sv]

    Inom projektet har hittills genomförts följande aktiviteter:

    1. Inhämtat teoretiska kunskaper inom området mikrovågsteknik
    2. Genomfört studier avseende vilka molekyler som är av intresse för stål- och metallindustrin att mäta på.
    3. Kontrollerat mot JPL databas samt NBS om dessa molekyler finns definierade i mikrovågsområdet av det elektromagnetiska spektret och då på vilka frekvenser.
    4. Designat och tillverkat en sensor, bestående av antenner, mixer samt LO, som klarar av att mäta vid de relevanta molekylära frekvenserna.
    5. Testat och utvärderat sensortekniken på laboratorienivå avseende signalkarak- täristik.
    6. Genomfört pilotförsök på MEFOS: i. Höga gastemperaturer; ii. Olika gaskoncentrationer
    7. Genomförtverksförsök: i. LKAB, Rotary Kiln; ii. Boliden Mineral, Kopparkonverter
    8. Utvärderat försöksdata
  • 24.
    Bååth, Lars B.
    Halmstad University, School of Business and Engineering (SET).
    Delivery test of the EISCAT Svalbard Radar Antenna1996Report (Refereed)
  • 25.
    Bååth, Lars B.
    Agellis Group AB, Lund, Sweden.
    Method and device for contactless level and interface detection2006Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    Method and apparatus for determining the thickness of material layers of a container-held substance comprising a first material disposed in an upper layer and a second material disposed in a lower layer, by transmitting a radio signal through the substance towards a container portion; receiving reflected signals from a surface of the upper layer, a surface of the second layer, and the container portion; varying the frequency of the transmitted signal to determine phase displacement between transmitted and reflected signals; determining optical distances to the surfaces and the container portion, dependent on the phase displacements; determining the thickness of one of said layers dependent on phase displacement through and index of refraction of that layer; and determining the thickness of the other layer dependent on the thickness of said one of said layers.

  • 26.
    Bååth, Lars B.
    Agellis Group AB, Lund, Sweden.
    Method for analysing a substance in a container2006Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    Method and apparatus for analyzing a substance in a container, the method comprising the steps of: disposing antenna means (3) at a predetermined geometrical distance (L) from a container portion (13); transmitting a signal from said antenna means through a surface portion (12) of the substance towards said container portion; receiving a first reflected signal in said antenna means from said container portion; determining a geometrical distance (L1) from the surface portion to the container portion; varying the frequency of the transmitted signal to determine a first phase displacement between the transmitted signal and the first reflected signal; determining an optical distance from the surface portion to the container portion based on the first phase displacement; and determining the index of refraction (nt) of said substance based on the optical and geometrical from the surface portion to the container portion.

  • 27.
    Bååth, Lars B.
    Onsala Space Observatory, Onsala, Sweden.
    mm VLBI1993In: VLBI Technology – Progress and Future Observational Possibilities: Proceedings of the International Symposium Held at Kyoto International Conference Hall on September 6-10, 1993 / [ed] Tetsuo Sasao, Seiji Manabe, Osamu Kameya & Makoto Inoue, Tokyo: Terra Scientific Publishing Company , 1993, p. 70-74Chapter in book (Refereed)
    Abstract [en]

    Very long Baseline Interferometry (VLBI) has now made its break-through into the mm wavelength regime. A global VLBI array has produced maps of radio sources at 3 mm since 1988 and development is under way to improve the sensitivity for VLBI also at 1 mm. This contribution discusses the present state of mm VLBI and the future developments.

  • 28.
    Bååth, Lars B.
    Halmstad University, School of Business and Engineering (SET).
    Radio Wave Interferometer Measurements of Slag Depth2003In: Iron & Steel society international technology conference and exposition 2003, Iron and Steel Society , 2003, p. 875-882Conference paper (Other academic)
    Abstract [en]

    During the past decade software to control metallurgical processes has improved to require new physical sensors for feedback. We present a non-invasive interferometric technique to simultaneously measure multiple levels in dynamic metallurgical processes, e.g. the foam-, slag-, emulsion-, and steel-layers in furnaces. The measurements are continuous and on-line during production.

  • 29.
    Bååth, Lars B.
    Halmstad University, School of Business and Engineering (SET).
    Tests of VLBI systems at Shanghai and Urumqi1996Report (Refereed)
  • 30.
    Bååth, Lars B.
    et al.
    Halmstad University, School of Business and Engineering (SET), Mechanical Engineering and Industrial Design (MTEK).
    Abu Dalou, Sadi Khalid
    Halmstad University, School of Business and Engineering (SET), Mechanical Engineering and Industrial Design (MTEK).
    Rosén, Bengt-Göran
    Halmstad University, School of Business and Engineering (SET), Mechanical Engineering and Industrial Design (MTEK).
    Surface topography with PDI holography2008In: Proceedings of the XII. International Colloquium on Surfaces / [ed] Michael Dietzsch, Aachen: Shaker Verlag, 2008, p. 10-Conference paper (Other academic)
    Abstract [en]

    This paper presents topographic measurements of metal surface with Point Diffraction Interferometer (PDI) technique. Interferogram of a surface is created and recorded with different phase offsets. These are then combined to create a phase offset map of the surface. We demonstrate the use with the presentation of our first surface topographic map

  • 31.
    Bååth, Lars B.
    et al.
    Halmstad University, School of Business and Engineering (SET).
    Buretta, Thomas A.
    Haystack Observatory.
    Clark, Thomas A.
    NASA Goddard Space Flight Center.
    Corey, Brian E.
    Haystack Observatory.
    Himwich, William E.
    NVI, Inc.lGoddard Space Flight Center.
    Ma, Chopo
    NASA Goddard Space Flight Center.
    Team China report1998Report (Refereed)
  • 32.
    Bååth, Lars B.
    et al.
    Halmstad University, School of Business and Engineering (SET), Mechanical Engineering and Industrial Design (MTEK).
    Löfgren, Hans
    Halmstad University, School of Business and Engineering (SET), Mechanical Engineering and Industrial Design (MTEK).
    Ny teknologi för avisning av vindkraftvingar2008Conference paper (Other academic)
  • 33.
    Bååth, Lars B.
    et al.
    Halmstad University, School of Business and Engineering (SET).
    Tilmaz, Jasin
    Halmstad University, School of Business and Engineering (SET).
    Kaestner, Anders
    Halmstad University, School of Business and Engineering (SET).
    Silverberg, Per
    Halmstad University, School of Business and Engineering (SET).
    Imaging with Interferometers1998In: Proceedings SSAB Symposium on Image Analysis, 1998, p. 4-Conference paper (Other academic)
    Abstract [en]

    A scanning device based on changes in the reflections of an electromagnetic wave for use on wood the image can be calculated.

  • 34.
    Bååth, Lars
    et al.
    Halmstad University, School of Business, Engineering and Science, Mechanical Engineering and Industrial Design (MTEK), Fotonik och mikrovågsteknik.
    Löfgren, Hans
    Halmstad University, School of Business, Engineering and Science, Mechanical Engineering and Industrial Design (MTEK).
    Ny teknik för avisning av vindkraftsvingar2008Report (Other academic)
    Abstract [en]

    This is a pilot study to investigate icing on wings of wind power turbines. In this report we present and discuss various ways and means to either heat water droplets or melt ice when formed on the wings of wind turbines. The situation is different from icing on wings of airplanes in that (1) the wings of wind turbines spend all of their time in the atmosphere where the risk of icing is highest and (2) the speed of wing to air varies over the wing where it is constant for an airplane. The form of the wind turbine wings also varies from tip to centre, to compensate for the varying relative air speed.

    We have concentrated on icing conditions at temperatures -10°C – 0°C and droplet sizes of 1-10 μm. Icing occurs also at much lower temperatures, but this will probably be because of direct freezing of water vapour to ice. This is presently outside the scope of our pilot project report.

    We conclude that

    • The form of the wing, especially on the contact area may be crucial to the icing problem.
    • Also the nano-metric structure of the wing surface can probably be designed so that the water droplets have a minimized contact area to the wing.

    Our pilot investigation also suggests the following:

    • Microwaves are much too inefficient to heat water or melt ice. Direct microwave devices should therefore not be developed. Indirect heating with microwaves is possible.
    • Millimeter waves are sufficiently efficient, but the generation is most probably too inefficient to be of any practical use.
    • Infrared waves are very efficient to heat water and melt ice and should be investigated.
    • Heat conduction is also efficient and should be pursued. Using microwaves to heat the wing surface which then conduct heat to the water/ice is a very efficient and robust method.

    Our pre-study suggests that the solution to avoid icing or de-ice wings of wind turbines most probably is not one single technology. The form and surface structure of the wings play important role for icing conditions. Both variables have to be modified depending on the latitude and atmospheric climate. The surface structure also has to be designed to vary over the wing, both along and across to be optimized for the mean conditions at the site. In addition, heating of the impact area, or at least the possibility to heat this, may be important to avoid loss of energy output due to ice.

    Further research is required. We strongly suggest investigating the water droplet flow over the wing as function of the cross section form, and the contact with the wing surface as function of the surface structure (e.g. Lotus effect).

    The present report is the result of a pre-study project. We will now continue with a deeper project which will concentrate on the form and surface structure suggestions which results from our analysis and flow simulations.

  • 35.
    Bååth, Lars
    et al.
    Halmstad University, School of Business, Engineering and Science, The Rydberg Laboratory for Applied Sciences (RLAS).
    Mantovani, F.
    Istituto di Radioastronomia del C.N.R., Bologna, Italy.
    Rantakyrö, F.T.
    Istituto di Radioastronomia del C.N.R., Bologna, Italy.
    High resolution interferometry of the QSO 1422+2021997In: Astronomy and Astrophysics. Supplement Series, ISSN 1286-4846, Vol. 125, no 1, p. 453-458Article in journal (Refereed)
    Abstract [en]

    We present VLA A-array observations at 8.4 and 15GHz and European VLBI Network (EVN) observations at 1.6GHz of the radio source 1422+202. It is suggested that 1422+202 is a Medium-size Object in the evolutionary sequence from Compact Steep-spectrum Sources to larger sized radio sources. The VLBI data were analysed with the phase referencing technique and we show that the EVN can work as a phase stable instrument for separations between the calibrator source and the target source up to ~ 10 degrees. With the VLA and VLBI observations we investigate some of the issues about the nucleus of 1422+202 and we discuss the possible cause for the low frequency variability detected while monitoring the source.

  • 36.
    Bååth, Lars
    et al.
    Halmstad University, School of Business and Engineering (SET), Mechanical Engineering and Industrial Design (MTEK), Fotonik och mikrovågsteknik.
    Nilsson, Emil
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS).
    Method and device for multidimensional imaging2007Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    PROBLEM TO BE SOLVED: To provide a method and system using transmission of an electromagnetic signal in order to determine the positions of reflection points by detecting the signals reflected at the reflection points in space. ; SOLUTION: The present invention provides a method, antenna, and system for defining the positions of the reflection points using microwave. The electromagnetic signal is generated at a determined frequency, and is transmitted by an antenna unit. The antenna unit comprises a transmitting antenna, and many receiving antennas that are separated at a known interval in the direction perpendicular to the main visual axis and are designed to receive a part of the reflected wave of the transmitted wave. A phase comparing means is connected to the transmitting antenna and receiving antennas, and a control unit connected to the phase comparing means can calculate an angle to the reflection points and calculate the distances to the reflection points. ; COPYRIGHT: (C)2007,JPO&INPIT

  • 37.
    Bååth, Lars
    et al.
    Halmstad University, School of Business and Engineering (SET), Mechanical Engineering and Industrial Design (MTEK), Fotonik och mikrovågsteknik.
    Nilsson, Emil
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS).
    Multi-dimensional imaging method and apparatus2007Patent (Other (popular science, discussion, etc.))
  • 38.
    Bååth, Lars
    et al.
    Halmstad University, School of Business and Engineering (SET), Mechanical Engineering and Industrial Design (MTEK).
    Nilsson, Emil
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS).
    Multi-dimensional imaging method and apparatus2007Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    A method, an antenna, and a system for determining positions for reflection points using microwaves. An electromagnetic wave signal is generated at a defined frequency, and transmitted by an antenna unit the antenna unit includes a transmitter antenna and a plurality of receiver antennas, separated by a known spacing perpendicular to a main line of sight and devised to receive reflected portions of the transmitted wave. Phase comparator means are connected to the transmitter antenna and the receiver antennas, and a control unit connected to the phase comparator means is operable to calculate an angle to a reflection point from detected phase difference between at least two receiver antennas and the spacing between said at least two receiver antennas, and to calculate a distance to the reflection point from detected phase difference between the transmitter antenna and a receiver antenna dependent on the frequency.

  • 39.
    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.

  • 40.
    Bååth, L.B.
    Onsala Space Observatory, Chalmers University of Technology, Gothenburg, Sweden.
    A closer look at active galactic nuclei — the great engines of the universe1992In: Physica scripta. T, ISSN 0281-1847, Vol. T43, p. 57-66Article in journal (Refereed)
    Abstract [en]

    The intensive radio emission from powerful radio galaxies and quasars Make these attractive candidates to become "standard candles" to probe the Universe. This paper discusses this possibility and the physics of the radio sources.

  • 41.
    Bååth, L.B.
    Onsala Space Observatory, Onsala, Sweden.
    AGN Variability and VLBI1994In: Multi-Wavelength Continuum Emission of Agn: Proceedings of the 159th Symposium of the International Astronomical Union, Held in Geneva, Switzerland, August 30 – September 3, 1993 / [ed] T.J.-L. Courvoisier & A. Blecha, Dordrecht: Kluwer Academic Publishers, 1994, p. 181-186Chapter in book (Refereed)
    Abstract [en]

    This contribution discusses the connection between variability in radio and optical with structural variations observed with VLBI. Structural changes do not have to start in the core, and intensity variations may be caused by components in the jet outside the core. The scenario is probably more complicated than present day theories assume.

  • 42.
    Bååth, L.B.
    Onsala Space Observatory, Chalmers University of Technology, Gothenburg, Sweden.
    Astrophysical global interferometry at Onsala Space Observatory1982In: Reports from the Observatory of Lund, ISSN 0349-4217, Vol. 18, p. 23-25Article in journal (Refereed)
  • 43.
    Bååth, L.B.
    Onsala Space Observatory, Chalmers University of Technology, Gothenburg, Sweden.
    Global Fringe Fitting Applied to 100 GHZ VLBI Data1991In: Frontiers of VLBI: Proceedings of the International VSOP Symposium held at the Institute of Space and Astronautical Science on December 5-7, 1989, and Proceedings of the mm-Wave VLBI Workshop held at the Nobeyama Radio Observatory on December 8-9, 1989 / [ed] H. Hirabayashi, M. Inoue & H. Kobayashi, Tokyo: Universal Academy Press , 1991, p. 353-359Chapter in book (Refereed)
    Abstract [en]

    Earlier epoches of mm VLBI observations relied on single baseline fit of delays and rates to find the fringes. This approach does not, however, make use of all available information and therefore is less sensitive than is necessary. Global fringe fitting makes use of all simultaneous data to find station related clock offsets and rates over a certain period of time. © Universal Academy Press, Inc.

  • 44.
    Bååth, L.B.
    Onsala Space Observatory, Chalmers University of Technology, Gothenburg, Sweden.
    Global fringe fitting applied to Mk3 VLBI data1991In: Radio Interferometry: Theory, Techniques, and Applications / [ed] T.J. Cornwell & R.A. Perley, San Francisco, USA: Astronomical Society of the Pacific , 1991, p. 321-325Conference paper (Refereed)
    Abstract [en]

    A system has been developed where data from a Mk3 VLBI processor can be read into the AIPS-package. Multiband and single-band delays can then be fitted globally by station. The technique has been used to phasereference a background to two radiogalaxies in the Abell cluster A2634.

  • 45.
    Bååth, L.B.
    Onsala Space Observatory, Chalmers University of Technology, Gothenburg, Sweden.
    High resolution images of Blazar cores1992In: Variability of Blazars: Proceedings of a conference in honour of the 100th anniversary of the birth of academician Yrjö Väisälä, held at Tuorla Observatory, University of Turku, Finland, January 6-10, 1991 / [ed] E. Valtaoja & M. Valtonen, Cambridge, UK: Cambridge University Press, 1992, p. 196-204Conference paper (Refereed)
  • 46.
    Bååth, L.B.
    Onsala Space Observatory, Chalmers University of Technology, Gothenburg, Sweden.
    High Resolution Observations of Low Frequency Variables at 932 MHz1987In: The Impact of VLBI on Astrophysics and Geophysics: Proceedings of the 129th Symposium of the International Astronomical Union held in Cambridge, Mass., U.S.A., May 10-15, 1987 / [ed] Reid, M. J. & Moran, J. M., Dordrecht: Kluwer Academic Publishers, 1987, p. 117-118Chapter in book (Refereed)
    Abstract [en]

    Fifteen sources known to be varying at low frequencies have been observed at six epochs during 1983–84 with a global VLBI array. Some of the sources show structural variations similar to the superluminals. Beaming effect may therefore play an important role at low as well as at higher frequencies.

  • 47.
    Bååth, L.B.
    Onsala Space Observatory, Chalmers University of Technology, Gothenburg, Sweden.
    Mapping in Practice1989In: Very Long Baseline Interferometry: Techniques and Applications / [ed] Felli, Marcello & Spencer, Ralph E., Dordrecht: Kluwer Academic Publishers, 1989, p. 199-230Chapter in book (Refereed)
    Abstract [en]

    The purpose of this lecture is to introduce the VLBI user to the practical details of mapping radio sources. I will concentrate on data processing and mapping with the AIPS (Thompson and D’Addario, 1982)-package. Other data reduction systems do exist, e.g. the Caltech-package and OLAF. These differ from AIPS mostly in the strategy for reaching the final and “best” map. It is more important to know the method and to be careful than what reduction procedure is used.

  • 48.
    Bååth, L.B.
    Onsala Space Observatory, Chalmers University of Technology, Gothenburg, Sweden.
    Millimetre VLBI capability status1993In: Sub-arcsecond Radio Astronomy: Proceedings of the Nuffield Radio Astronomy Laboratories' conference, held in Manchester, July 20–24, 1992 / [ed] R. J. Davis & R. S. Booth, Cambridge: Cambridge University Press, 1993, p. 431-433Chapter in book (Refereed)
    Abstract [en]

    The development of new reveiver and data reduction techniques have now made VLBI at mm wavelengths possible. This contribution discusses the capability of the present and future VLBI networks at λ1 and 3mm and compares with radio interferometers at other wavelength regimes.

  • 49.
    Bååth, L.B.
    Onsala Space Observatory, Chalmers University of Technology, Gothenburg, Sweden.
    mm VLBI vs. VSOP1991In: Frontiers of VLBI: Proceedings of the International VSOP Symposium held at the Institute of Space and Astronautical Science on December 5-7, 1989, and Proceedings of the mm-Wave VLBI Workshop held at the Nobeyama Radio Observatory on December 8-9, 1989 / [ed] H. Hirabayashi, M. Inoue & H. Kobayashi, Tokyo: Universal Academy Press , 1991, p. 197-201Chapter in book (Refereed)
    Abstract [en]

    VSOP-to-ground VLBI and mm VLBI are both needed if we want to further increase our knowledge of quasars, radio galaxies and their radio jets, mm VLBI will be a better instrument to study the "central engine" while satellite VLBI will better show the structure of the jets. The two instruments complement each other, and it is important to have a close collaboration. © Universal Academy Press, Inc.

  • 50.
    Bååth, L.B.
    Onsala Space Observatory, Chalmers University of Technology, Gothenburg, Sweden.
    New millimetric VLBI results1992In: Extragalactic radio sources - from beams to jets: Proceedings of the 7th IAP Meeting held at the Institut d'Astrophysique de Paris, Paris, France 2-5 July 1991 / [ed] J. Roland, H. Sol and G. Pelletier, Cambridge: Cambridge University Press, 1992, p. 137-144Conference paper (Refereed)
123 1 - 50 of 144
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