JMC method applied to active control of sound: Theoretical extensions and new source configurations: Dissertation

Seppo Uosukainen

    Research output: ThesisDissertationCollection of Articles

    Abstract

    The active control of sound can be used to control the acoustics of interior spaces, to reduce the sound radiation of machines and equipment, to decrease and even to refine noise in a more comfortable form in, e.g., ducts and vehicles.The JMC method, developed by Jessel, Mangiante and Canévet, is a systematic tool in the active control of sound.It is applied mostly by using scalar weighting, in which all the first-order field quantities and primary source strengths are weighted similarly.In this thesis, a modified JMC method is developed, in which the primary sources remain unchanged in all cases, the situation being more similar to a practical one.On the basis of the modified JMC method, the vector and dyadic weightings are defined, the former weighting the sound pressure and particle velocity independently, and the latter also changing the direction of the particle velocity.These new weightings increase the possibilities in field reshaping.In the JMC method, three types of secondary sources are needed: monopoles, dipoles and quadripoles.It is found that in multi-source configurations, the last ones are automatically generated by the dependence of the dipole distribution on the lateral coordinates.Four three-unit approximations of the JMC element (i.e., detector-actuator combination according to the JMC method) are developed, in which one of either the primary field quantities or the secondary source quantities is approximated by the help of a field impedance function.For waveguides (e.g., ducts), ideal unidirectional three-element and two-element JMC source configurations and their approximations are discovered.The inter-channel delay in the control structure of the two-element actuators may be optimized downstream or upstream, or omitted altogether.Especially the last case turns out to be advantageous in the practical implementation of digital control systems.The adaptive JMC structures for the new ideal two-element solutions are presented.The results of this thesis enlarge the possibilities in the active control of sound and facilitate more useful applications to be realized in ducts and three-dimensional spaces.
    Original languageEnglish
    QualificationDoctor Degree
    Awarding Institution
    • Aalto University
    Supervisors/Advisors
    • Karjalainen, Matti, Supervisor, External person
    Award date28 May 1999
    Place of PublicationEspoo
    Publisher
    Print ISBNs951-38-5377-2
    Electronic ISBNs951-38-5378-0
    Publication statusPublished - 1999
    MoE publication typeG5 Doctoral dissertation (article)

    Fingerprint

    active control
    acoustics
    configurations
    ducts
    theses
    actuators
    dipoles
    dyadics
    sound pressure
    approximation
    monopoles
    upstream
    vehicles
    impedance
    scalars
    waveguides
    detectors
    radiation

    Keywords

    • ducts
    • JMC method
    • JMC element
    • active noise control
    • waveguide
    • unidirectional actuators

    Cite this

    Uosukainen, Seppo. / JMC method applied to active control of sound : Theoretical extensions and new source configurations: Dissertation. Espoo : VTT Technical Research Centre of Finland, 1999. 70 p.
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    title = "JMC method applied to active control of sound: Theoretical extensions and new source configurations: Dissertation",
    abstract = "The active control of sound can be used to control the acoustics of interior spaces, to reduce the sound radiation of machines and equipment, to decrease and even to refine noise in a more comfortable form in, e.g., ducts and vehicles.The JMC method, developed by Jessel, Mangiante and Can{\'e}vet, is a systematic tool in the active control of sound.It is applied mostly by using scalar weighting, in which all the first-order field quantities and primary source strengths are weighted similarly.In this thesis, a modified JMC method is developed, in which the primary sources remain unchanged in all cases, the situation being more similar to a practical one.On the basis of the modified JMC method, the vector and dyadic weightings are defined, the former weighting the sound pressure and particle velocity independently, and the latter also changing the direction of the particle velocity.These new weightings increase the possibilities in field reshaping.In the JMC method, three types of secondary sources are needed: monopoles, dipoles and quadripoles.It is found that in multi-source configurations, the last ones are automatically generated by the dependence of the dipole distribution on the lateral coordinates.Four three-unit approximations of the JMC element (i.e., detector-actuator combination according to the JMC method) are developed, in which one of either the primary field quantities or the secondary source quantities is approximated by the help of a field impedance function.For waveguides (e.g., ducts), ideal unidirectional three-element and two-element JMC source configurations and their approximations are discovered.The inter-channel delay in the control structure of the two-element actuators may be optimized downstream or upstream, or omitted altogether.Especially the last case turns out to be advantageous in the practical implementation of digital control systems.The adaptive JMC structures for the new ideal two-element solutions are presented.The results of this thesis enlarge the possibilities in the active control of sound and facilitate more useful applications to be realized in ducts and three-dimensional spaces.",
    keywords = "ducts, JMC method, JMC element, active noise control, waveguide, unidirectional actuators",
    author = "Seppo Uosukainen",
    note = "Project code: R9SU00259",
    year = "1999",
    language = "English",
    isbn = "951-38-5377-2",
    series = "VTT Publications",
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    JMC method applied to active control of sound : Theoretical extensions and new source configurations: Dissertation. / Uosukainen, Seppo.

    Espoo : VTT Technical Research Centre of Finland, 1999. 70 p.

    Research output: ThesisDissertationCollection of Articles

    TY - THES

    T1 - JMC method applied to active control of sound

    T2 - Theoretical extensions and new source configurations: Dissertation

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    Y1 - 1999

    N2 - The active control of sound can be used to control the acoustics of interior spaces, to reduce the sound radiation of machines and equipment, to decrease and even to refine noise in a more comfortable form in, e.g., ducts and vehicles.The JMC method, developed by Jessel, Mangiante and Canévet, is a systematic tool in the active control of sound.It is applied mostly by using scalar weighting, in which all the first-order field quantities and primary source strengths are weighted similarly.In this thesis, a modified JMC method is developed, in which the primary sources remain unchanged in all cases, the situation being more similar to a practical one.On the basis of the modified JMC method, the vector and dyadic weightings are defined, the former weighting the sound pressure and particle velocity independently, and the latter also changing the direction of the particle velocity.These new weightings increase the possibilities in field reshaping.In the JMC method, three types of secondary sources are needed: monopoles, dipoles and quadripoles.It is found that in multi-source configurations, the last ones are automatically generated by the dependence of the dipole distribution on the lateral coordinates.Four three-unit approximations of the JMC element (i.e., detector-actuator combination according to the JMC method) are developed, in which one of either the primary field quantities or the secondary source quantities is approximated by the help of a field impedance function.For waveguides (e.g., ducts), ideal unidirectional three-element and two-element JMC source configurations and their approximations are discovered.The inter-channel delay in the control structure of the two-element actuators may be optimized downstream or upstream, or omitted altogether.Especially the last case turns out to be advantageous in the practical implementation of digital control systems.The adaptive JMC structures for the new ideal two-element solutions are presented.The results of this thesis enlarge the possibilities in the active control of sound and facilitate more useful applications to be realized in ducts and three-dimensional spaces.

    AB - The active control of sound can be used to control the acoustics of interior spaces, to reduce the sound radiation of machines and equipment, to decrease and even to refine noise in a more comfortable form in, e.g., ducts and vehicles.The JMC method, developed by Jessel, Mangiante and Canévet, is a systematic tool in the active control of sound.It is applied mostly by using scalar weighting, in which all the first-order field quantities and primary source strengths are weighted similarly.In this thesis, a modified JMC method is developed, in which the primary sources remain unchanged in all cases, the situation being more similar to a practical one.On the basis of the modified JMC method, the vector and dyadic weightings are defined, the former weighting the sound pressure and particle velocity independently, and the latter also changing the direction of the particle velocity.These new weightings increase the possibilities in field reshaping.In the JMC method, three types of secondary sources are needed: monopoles, dipoles and quadripoles.It is found that in multi-source configurations, the last ones are automatically generated by the dependence of the dipole distribution on the lateral coordinates.Four three-unit approximations of the JMC element (i.e., detector-actuator combination according to the JMC method) are developed, in which one of either the primary field quantities or the secondary source quantities is approximated by the help of a field impedance function.For waveguides (e.g., ducts), ideal unidirectional three-element and two-element JMC source configurations and their approximations are discovered.The inter-channel delay in the control structure of the two-element actuators may be optimized downstream or upstream, or omitted altogether.Especially the last case turns out to be advantageous in the practical implementation of digital control systems.The adaptive JMC structures for the new ideal two-element solutions are presented.The results of this thesis enlarge the possibilities in the active control of sound and facilitate more useful applications to be realized in ducts and three-dimensional spaces.

    KW - ducts

    KW - JMC method

    KW - JMC element

    KW - active noise control

    KW - waveguide

    KW - unidirectional actuators

    M3 - Dissertation

    SN - 951-38-5377-2

    T3 - VTT Publications

    PB - VTT Technical Research Centre of Finland

    CY - Espoo

    ER -

    Uosukainen S. JMC method applied to active control of sound: Theoretical extensions and new source configurations: Dissertation. Espoo: VTT Technical Research Centre of Finland, 1999. 70 p.