Browsing by Author "Maunuksela, J."

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  • Kinetic Roughening in Slow Combustion of Paper
    (1997) Maunuksela, J.; Myllys, M.; Kähkönen, O.-P.; Timonen, J.; Provatas, N.; Alava, M. J.; Ala-Nissilä, Tapio
     School of Science | A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    We present results from an experimental study on the kinetic roughening of slow combustion fronts in paper sheets. The sheets were positioned inside a combustion chamber and ignited from the top to minimize convection effects. The emerging fronts were videotaped and digitized to obtain their time-dependent heights. The data were analyzed by calculating two-point correlation functions in the saturated regime. Both the growth and roughening exponents were determined and found consistent with the Kardar-Parisi-Zhang equation, in agreement with recent theoretical work.
  • Kinetic roughening in slow combustion of paper
    (2001) Myllys, M.; Maunuksela, J.; Alava, M.; Ala-Nissilä, Tapio; Merikoski, J.; Timonen, J.
     School of Science | A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    Results of experiments on the dynamics and kinetic roughening of one-dimensional slow-combustion fronts in three grades of paper are reported. Extensive averaging of the data allows a detailed analysis of the spatial and temporal development of the interface fluctuations. The asymptotic scaling properties, on long length and time scales, are well described by the Kardar-Parisi-Zhang (KPZ) equation with short-range, uncorrelated noise. To obtain a more detailed picture of the strong-coupling fixed point, characteristic of the KPZ universality class, universal amplitude ratios, and the universal coupling constant are computed from the data and found to be in good agreement with theory. Below the spatial and temporal scales at which a crossover takes place to the standard KPZ behavior, the fronts display higher apparent exponents and apparent multiscaling. In this regime the interface velocities are spatially and temporally correlated, and the distribution of the magnitudes of the effective noise has a power-law tail. The relation of the observed short-range behavior and the noise as determined from the local velocity fluctuations is discussed.
  • Maunuksela et al. Reply to the comment of Amaral and Makse
    (1998) Maunuksela, J.; Myllys, M.; Timonen, J.; Kuittu, M.; Ala-Nissilä, Tapio; Alava, M. J.; Provatas, N.
     School of Science | B1 Kirjoitus tieteellisessä aikakauslehdessä
    A Reply to the Comment by Luis A. Nunes Amaral and Hernan A. Makse.
  • Reply to the comment of Makse and Amaral
    (1998) Maunuksela, J.; Myllys, J.; Timonen, J.; Ala-Nissilä, T.; Kuittu, M.; Alava, M.J.; Provatas, N.
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    A Reply to the Comment by Luis A. Nunes Amaral and Hernan A. Makse.
  • Scaling and Noise in Slow Combustion of Paper
    (2000) Myllys, M.; Maunuksela, J.; Alava, M. J.; Ala-Nissilä, Tapio; Timonen, J.
     School of Science | A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    We present results of high resolution experiments on kinetic roughening of slow combustion fronts in paper, focusing on short length and time scales. Using three different grades of paper, we find that the combustion fronts show apparent spatial and temporal multiscaling at short scales. The scaling exponents decrease as a function of the order of the corresponding correlation functions. The noise affecting the fronts reveals short range temporal and spatial correlations, and non-Gaussian noise amplitudes. Our results imply that the overall behavior of slow combustion fronts cannot be explained by standard theories of kinetic roughening.
  • Temporal and Spatial Persistence of Combustion Fronts in Paper
    (2003) Merikoski, J.; Maunuksela, J.; Myllys, M.; Timonen, J.; Alava, Mikko J.
     School of Science | A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    The spatial and temporal persistence, or first-return distributions are measured for slow-combustion fronts in paper. The stationary temporal and (perhaps less convincingly) spatial persistence exponents agree with the predictions based on the front dynamics, which asymptotically belongs to the Kardar-Parisi-Zhang universality class. The stationary short-range and the transient behavior of the fronts are non-Markovian, and the observed persistence properties thus do not agree with the predictions based on Markovian theory. This deviation is a consequence of additional time and length scales, related to the crossovers to the asymptotic coarse-grained behavior.
  • Temporal and spatial persistence of combustion fronts in paper
    (2003-01-17) Merikoski, J.; Maunuksela, J.; Myllys, Markko; Timonen, J.; Alava, M. J.
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    The persistence properties of fluctuating combustion fronts in paper were studied. Asymptotically both temporal and spatial persistence follow the theoretical expectations for the stationary case. For the short-range behaviors, the KPZ physics is irrelevant, and the first-return distributions deviate from those based on a stationary Markovian stochastic process. Instead, the physics indicates the presence of memory effects.