Sökning: "Imperfections"

Visar resultat 11 - 15 av 129 avhandlingar innehållade ordet Imperfections.

  1. 11. An electronic warfare perspective on time difference of arrival estimation subject to radio receiver imperfections

    Författare :Johan Falk; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Signal processing; Signalbehandling;

    Sammanfattning : In order to ensure secure communication in digital military radio systems, multiple methods are used to protect the transmission from being intercepted by enemy electronic warfare systems. An intercepted transmission can be used to estimate several parameters of the transmitted signal such as its origin (position or direction) and of course the transmitted message itself. LÄS MER

  3. 12. Rolling Contact Fatigue of Railway Wheels Towards Tread Life Prediction through Numerical Modelling Considering Material Imperfections, Probabilistic Loading and Operational Data

    Författare :Anders Ekberg; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY;

    Sammanfattning : Higher train speeds and increased axle loads have led to larger forces acting on the railway wheels. Also, efforts are presently being made to straighten existing tracks, to design new tracks with larger curve radii and to optimize bogie designs. LÄS MER

  4. 13. Train---Track Interaction. Coupling of Moving and Stationary Dynamic Systems: Theoretical and Experimental Analysis of Railway Structures Considering Wheel and Track Imperfections

    Författare :Jens Nielsen; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY;

    Sammanfattning : A general and well-structured method is advanced for analysis of the vertical dynamic interaction between a train and its track. The trains studied are modelled as linear or non-linear discrete mass-spring-damper systems. LÄS MER

  5. 14. Simulation of dynamic instabilities during high rate deformation of ductile bars and plates

    Författare :Kristina Nilsson; Mekanik; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; numerical simulation; non-linear; wave propagation; multiple necking; necking; buckling; fracture; Mechanical engineering; Maskinteknik; finite elements; cohesive elements; dynamic; J2-flow theory; J2-deformation theory; viscoplastic; background inertia;

    Sammanfattning : In this thesis, some of the phenomena occurring in plates and cylindrical bars subjected to dynamic loading are investigated. Numerical simulations using a dynamic finite element code are performed for a number of different sized specimens with various initial surface imperfections. Typically imposed loading velocities are in the range 10m/s.. LÄS MER

  7. 15. On the analysis of cast structure and its changes during hot working of forging ingots

    Författare :Jan Sarnet; Hasse Fredriksson; Alec Mitchell; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Materials science; Teknisk materialvetenskap;

    Sammanfattning : Forging ingots are hot worked to consolidate structural imperfections and refine the microstructure. Possible imperfections are segregations, porosities, cracks, and inclusions. In this thesis, techniques and methods for the characterisation of behaviour and properties of ingots and forgings. LÄS MER