Sökning: "frequency variations"

Visar resultat 1 - 5 av 341 avhandlingar innehållade orden frequency variations.

  1. 1. The Frequency of the Frequency : On Hydropower and Grid Frequency Control

    Författare :Linn Saarinen; Urban Lundin; Per Norrlund; Bengt Carlsson; Kjetil Uhlen; Uppsala universitet; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; hydropower; frequency control; governors; power system stability; inertia; primary control; Engineering Science with specialization in Science of Electricity; Teknisk fysik med inriktning mot elektricitetslära;

    Sammanfattning : Variations in the electricity consumption and production connected to the power system have to be balanced by active control. Hydropower is the most important balancing resource in the Nordic system, and will become even more important as the share of variable renewable energy sources increases. LÄS MER

  3. 2. Graphene field-effect transistors for high frequency applications

    Författare :Muhammad Asad; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; high frequency; Graphene; transit frequency; transconductance; maximum frequency of oscillation; contact resistance; microwave electronics; field-effect transistors;

    Sammanfattning : Rapid development of wireless and internet communications requires development of new generation high frequency electronics based on new device concepts and new materials. The very high intrinsic velocity of charge carriers in graphene makes it promising new channel material for high frequency electronics. LÄS MER

  4. 3. Trapezius muscle fatigue and electromyographic frequency analysis

    Författare :Tommy Öberg; Linköpings universitet; []
    Nyckelord :EMG; Spectrum; Frequency; Fatigue; Trapezius; Myalgia; MEDICINE; MEDICIN;

    Sammanfattning : This study, comprising 6 separate articles, is concerned with different validity and reliability aspects of the electromyogram mean power frequency (MPF) as an estimator of localized musele fatigue in the trapezius muscle. A series of new, and partly controversial and problematic findings are reported. LÄS MER

  5. 4. Recombination frequency variations in Drosophila melanogaster

    Författare :Jack Valentin; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES;

    Sammanfattning : .... LÄS MER

  7. 5. Optimization modeling of frequency reserves and inertia in the transition to a climate-neutral electricity system

    Författare :Jonathan Ullmark; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; generation expansion planning; frequency reserves; inertia; Energy system modeling; synthetic inertia; frequency control;

    Sammanfattning : The ongoing transition towards electricity production systems that are dominated by wind and solar power challenge both the traditional strategy for meeting a varying electricity demand and the traditional way of controlling the AC frequency of the electricity grid. This work investigates how frequency reserves (FR) and inertia, as well as inter-hourly variation management interact in the transition to a climate-neutral electricity system. LÄS MER