Sökning: "Johan Alfredsson"

Hittade 5 avhandlingar innehållade orden Johan Alfredsson.

  1. 1. Improving the Energy Efficiency of Cellular IoT Device

    Författare :Muhammad Tahir Abbas; Karl-Johan Grinnemo; Johan Eklund; Mohammad Rajiullah; Stefan Alfredsson; Peter Sjödin; Karlstads universitet; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; CIoT; 3GPP; energy saving; mMTC; NB-IoT; LTE-M; EC-GSM- IoT; Computer Science; Datavetenskap;

    Sammanfattning : Cellular Internet of Things (CIoT) has emerged as a promising technology to support applications that generate infrequent data. One requirement on these applications, often battery-powered devices, is low energy consumption to enable extended battery life. LÄS MER

  3. 2. A numerical and experimental investifgation on surface and sub-surface initiation of contact fatigue cracks at cylindrical contacts

    Författare :Johan Dahlberg; Bo Alfredsson; Johas Ringsberg; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Other engineering mechanics; Övrig teknisk mekanik;

    Sammanfattning : .... LÄS MER

  4. 3. On the asperity point load mechanism for rolling contact fatigue

    Författare :Johan Dahlberg; Bo Alfredsson; Sören Sjöström; KTH; []
    Nyckelord :Rolling contact fatigue; Spalling; Asperity contact; Point load; Micro-cracks; Traction; Applied slip; TECHNOLOGY; TEKNIKVETENSKAP;

    Sammanfattning : Rolling contact fatigue is a damage process that may arise in mechanical applications with repeated rolling contacts. Some examples are: gears; cams; bearings; rail/wheel contacts. The resulting damage is often visible with the naked eye as millimeter sized surface craters. LÄS MER

  5. 4. Effect of drag reducing plasma actuators using LES

    Författare :Romain Futrzynski; Gunilla Efraimsson; P. Henrik Alfredsson; Emma Alenius; Johan Revstedt; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; flow control; drag reduction; plasma actuator; DMD; LES; optimization; pulsating flow; strömningskontroll; motståndsminskning; plasmaaktuator; DMD; LES; optimering; pulserande strömning; Engineering Mechanics; Teknisk mekanik;

    Sammanfattning : The work performed in this thesis explores new ways of reducing the drag of ground vehicles. Specifically, the effect of plasma actuators are investigated numerically with the intention to delay separation around a half-cylinder, a geometry chosen to represent a simplified A-pillar of a truck. LÄS MER

  7. 5. High Temperature Fatigue Crack Growth in a Ni-based Superalloy : Modelling Including the Interaction of Dwell Times

    Författare :Erik Storgärds; Kjell Simonsson; Johan Moverare; Tomas Månsson; Bo Alfredsson; Linköpings universitet; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY;

    Sammanfattning : Safe life of gas turbines is always of major concern for manufacturers in order to ensure passenger safety and stable continuous power output. An increasing amount of resources have been put into research and development to assure that all safety aspects are covered in the design of new turbines and to ensure that enough frequent service intervals are scheduled to avoid complications. LÄS MER