Sökning: "Physics modeling"

Visar resultat 21 - 25 av 361 avhandlingar innehållade orden Physics modeling.

  1. 21. Multiscale modeling of atomic transport phenomena in ferritic steels

    Författare :Luca Messina; Pär Olsson; Nils Sandberg; Pål Efsing; Pascal Bellon; KTH; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; diffusion; impurities; iron; metals; kinetic Monte Carlo; ab initio; mean field; defects; embrittlement; reactor pressure vessel; neural networks; Fysik; Physics;

    Sammanfattning : Defect-driven transport of impurities plays a key role in the microstructure evolution of alloys, and has a great impact on the mechanical properties at the macroscopic scale. This phenomenon is greatly enhanced in irradiated materials because of the large amount of radiation-induced crystal defects (vacancies and interstitials). LÄS MER

  3. 22. Ghosts and machines : regularized variational methods for interactive simulations of multibodies with dry frictional contacts

    Författare :Claude Lacoursière; Bo Kåggström; Ander Klarbring; Umeå universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Discrete mechanics; Variational method; Contact problems; Impacts; Least action principle; Saddle point problems; Lagrange Multipliers; Constrained systems; Multibody Systems; Numerical regularization; Constraint realization; Constraint stabilization; Dry friction; Differential Algebraic Equations; Nonsmooth problems; Linear Complementarity; Quaternion algebra; Numerical linear algebra; Physics modeling; Interactive simulation; Numerical stability; Rigid body dynamics; Dissipative systems; Computational physics; Beräkningsfysik;

    Sammanfattning : A time-discrete formulation of the variational principle of mechanics is used to provide a consistent theoretical framework for the construction and analysis of low order integration methods. These are applied to mechanical systems subject to mixed constraints and dry frictional contacts and impacts---machines. LÄS MER

  4. 23. Numerical modeling of auroral processes

    Författare :Jörgen Vedin; Kjell Rönnmark; Robert Lysak; Umeå universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; space plasma physics; auroral acceleration region; auroral current circuit; Alfvén waves; parallel electric fields; equation of state; fluid simulation; PIC simulation; Space physics; Rymdfysik;

    Sammanfattning : One of the most conspicuous problems in space physics for the last decades has been to theoretically describe how the large parallel electric fields on auroral field lines can be generated. There is strong observational evidence of such electric fields, and stationary theory supports the need for electric fields accelerating electrons to the ionosphere where they generate auroras. LÄS MER

  5. 24. Determining and Optimizing the Current and Magnetic Field Dependence of Spin-Torque and Spin Hall Nano-Oscillators : Toward Next-Generation Nanoelectronic Devices and Systems

    Författare :Seyed Amir Hossein Banuazizi; Johan Åkerman; Erik Wahlström; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; nanoelectronics; spintronics; nanomagnetism; ferromagnetic materials; microwave oscillators; magnetization dynamics; spin waves; giant magneto-resistance; spin Hall effect; spin-torque nano-oscillators; spin Hall nano-oscillators; numerical modeling; electrical characterization; microwave characterization; magnetic force microscopy.; Fysik; Physics; Teknisk materialvetenskap; Materials Science and Engineering; Informations- och kommunikationsteknik; Information and Communication Technology; Electrical Engineering; Elektro- och systemteknik;

    Sammanfattning : Spin-torque and spin Hall nano-oscillators are nanoscale devices (about 100 nm) capable of producing tunable broadband high-frequency microwave signals ranging from 0.1 GHz to over 65 GHz that several research groups trying to reach up to 200 - 300 GHz. LÄS MER

  7. 25. Developing semi-empirical ab initio based potentials in materials modeling

    Författare :Jie Fu; Anatoly Belonoshko; Michael Odelius; KTH; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Fysik; Physics;

    Sammanfattning : Ab initiocalculation based on density function theory (DFT) is an accu-rate and efficient method for modelling material properties. It is performedby solving the Shrödinger equations with a few assumptions to obtain thephysical properties of the system. It is very computational demanding whendealing with large systems or long-time simulations. LÄS MER