Sökning: "rolling"

Visar resultat 11 - 15 av 380 avhandlingar innehållade ordet rolling.

  1. 11. Roller skis' rolling resistance and grip characteristics : influences on physiological and performance measures in cross-country skiers

    Författare :Mats Ainegren; Peter Carlsson; Marko Laaksonen; Mittuniversitetet; []
    Nyckelord :MEDICIN OCH HÄLSOVETENSKAP; MEDICAL AND HEALTH SCIENCES; MEDICIN OCH HÄLSOVETENSKAP; MEDICAL AND HEALTH SCIENCES; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Adjustable grip; blood lactate; centre of pressure; cycle length; cycle rate; economy; efficiency; friction coefficient; heart rate; normal force; OBLA; oxygen uptake; power; ratcheted wheel; ratings of perceived exertion; roller skis; rolling resistance; tangential force; time to exhaustion;

    Sammanfattning : The aim of this thesis was to investigate roller ski characteristics; classical and freestyle roller skis’ rolling resistance coefficients (μR) and classical style roller skis’ static friction coefficients (μS), and to study the influence of different μR and μS on cross-country skiers’ performance and both physiological and biomechanical indices. The aim was also to study differences in skiing economy and efficiency between recreational skiers, female and male junior and senior elite cross-country skiers. LÄS MER

  3. 12. The influence of modelling parameters on the simulation of car tyre rolling losses and rolling noise

    Författare :Carsten Hoever; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; rolling resistance; modelling parameters; parameter study; radiation; tyre road noise; tyres; tyre road interaction; waveguide finite element;

    Sammanfattning : Due to legislative changes within the EU there is an increased demand for improvement in car tyre rolling resistance and noise generation. Yet, apart from empirical data based on measurements, there is little information concerning the relationship between rolling resistance and rolling noise generation. LÄS MER

  4. 13. Vibrations induced by surface roughness in nonlinear rolling contacts

    Författare :Oskar Erik Lundberg; Ines Lopez Arteaga; Svante Finnveden; Will Graham; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Rolling contact; nonlinear contact; contact stiffness; contact filter; state-dependent method; relative displacement; wheel-rail contact; Vehicle and Maritime Engineering; Farkostteknik;

    Sammanfattning : For efficient transportation in either trains, busses or passenger cars, rolling elements such as wheels, tyres, bearings and transmission elements are fundamental. The energy efficiency and the generation of noise and vibrations in rolling contacts depend on the surface roughness of contacting bodies. LÄS MER

  5. 14. Modelling and experimental testing of truck tyre rolling resistance

    Författare :Jukka Hyttinen; Lars Drugge; Jenny Jerrelind; James Busfield; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Truck tyre; PRF; filler-reinforced rubber; ambient temperature; rubber testing; constitutive modelling; parametrisation; rolling resistance; load cell; Fletcher-Gent effect; Payne effect; Lastbilsdäck; PRF; förstärkande fyllmedel; gummi; omgivningstemperatur; gummiprovning; konstitutiv modellering; parametrisering; rullmotstånd; lastcell; Fletcher-Gent effekt; Payne effekt; Teknisk mekanik; Engineering Mechanics;

    Sammanfattning : Truck transport offers a versatile way to ship goods in regional, long haulage and urban applications. However, the heavy truck sector accounts for 6 % of total greenhouse gas emissions in the European Union. Therefore, there is a need for a substantial reduction of these emissions to secure the sustainability of Earth for future generations. LÄS MER

  7. 15. Keep it rolling : Straight-line orientation in South African ball-rolling dung beetles

    Författare :Lana Khaldy; Funktionell zoologi; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Ball-rolling dung beetle; Orientation; Heading direction network; Compass; Weighting; Celestial cues; Sun; Polarised light;

    Sammanfattning : Representing a substantial range and variety in morphological and ecological niche, found on all continents of the globe (except for the Antarctic), the ball-rolling dung beetles provide an excellent model in which to study the heading direction network and the factors by which it is influenced. As soon as a ball-rolling dung beetle has located a fresh dung pile to feed on, it immediately starts shaping a piece of dung into a ball, rolling it away from the dung pat in as straight of a trajectory as the terrain allows. LÄS MER