TY  - JOUR
A1  - Kurths, Jürgen
A1  - Schwarz, Udo
A1  - Witt, Annette
T1  - Non-linear data analysis in solar radio astronomy
N2  - We have discussed some tools from nonlinear dynamics which may help to analyze transient phenomena, such as solar bursts. The structure function known from turbulence theory is an appropriate method to find out some scaling behavior of fluctuations in time. More generally, the wavelet analysis, which is some generalization of the power spectrum, exhibits information on the location as well as the size of hidden characteristic features. Applying both techniques to microwave bursts, we have found some scaling properties that refer to the existence of hierarchic time structures. This is in good accordance with the electric circuit model for describing the flare-particle energization process.
Y1  - 1995
UR  - http://www.agnld.uni-potsdam.de/~shw/Paper/lnp.ps.gz
ER  - 
TY  - THES
A1  - Schwarz, Udo
T1  - Zeitreihenanalyse astrophysikalischer Aktivitätsphänomene
Y1  - 1994
ER  - 
TY  - BOOK
A1  - Voss, Henning U.
A1  - Kurths, Jürgen
A1  - Schwarz, Udo
T1  - Reconstruction of grand minima of solar activity from radiocarbon data : linear and nonlinear signal analysis
T3  - Preprint NLD
Y1  - 1996
VL  - 28
PB  - Univ.
CY  - Potsdam
ER  - 
TY  - JOUR
A1  - Spahn, Frank
A1  - Katzorke, Ines
A1  - Petzschmann, Olaf
A1  - Schwarz, Udo
A1  - Kurths, Jürgen
T1  - Cluster instabiliy of granular assemblies
Y1  - 1997
ER  - 
TY  - JOUR
A1  - Spahn, Frank
A1  - Schwarz, Udo
A1  - Kurths, Jürgen
T1  - Clustering of granular assemblies with temperature dependent restitution under Keplerian differential rotation
Y1  - 1997
ER  - 
TY  - JOUR
A1  - Feudel, Ulrike
A1  - Jansen, Wolfgang
A1  - Kurths, Jürgen
A1  - Schwarz, Udo
A1  - Voss, Henning U.
T1  - Solar variability : simple models and proxy data
Y1  - 1997
SN  - 4-274-90187-4
ER  - 
TY  - JOUR
A1  - Schwarz, Udo
T1  - Das Maunder-Minimum : alles sonnenklar, oder?
N2  - Im vorletzten Absatz des o.g. Kurzberichtes befindet sich eine falsche Aussage zur C14-Produktion waehrend des Maunder-Minimums. Wie aus der in meiner Abbildung gezeigten Delta C14-Haeufigkeit fuer den Zeitraum des Maunder-Minimums hervorgeht, war die C14-Produktion zu dieser Zeit erhoeht statt, wie von Herrn Buehrke und anderen Autoren in der Literatur behauptet, erniedrigt. Die allgemein akzeptierte Begruendung fuer die erhoehte C14-Produktion lautet: Der geringere Sonnenwind schirmt die Erde weniger stark von der kosmischen Strahlung ab.
Y1  - 1994
ER  - 
TY  - JOUR
A1  - Kurths, Jürgen
A1  - Schwarz, Udo
T1  - Chaos theory and radio emission
N2  - The application of chaos theory has become popular to understand the nature of various features of solar activity because most of them are far from regular. The usual approach, however, that is basing on finding low- dimensional structures of the underlying processes seems to be successful only in a few exceptional cases, such as in rather coherent phenomena as coronal pulsations. It is important to note that most phenomena in solar radio emission are more complex. We present two kinds of techniques from nonlinear dynamics which can be useful to analyse such phenomena: i] Fragmentation processes observed in solar spike events are studied by means of symbolic dynamics methods. Different measures of complexity calculated from such observations reveal that there is some order in this fragmentation. ii] Bursts are a typical transient phenomenon. To study energization processes causing impulsive microwave bursts, the wavelet analysis is applied. It exhibits structural differences of the pre- and post-impulsive phase in cases where the power spectra of both are not distinct.
Y1  - 1994
UR  - http://www.agnld.uni-potsdam.de/~shw/Paper/Review.ps.gz
ER  - 
TY  - JOUR
A1  - Kurths, Jürgen
A1  - Schwarz, Udo
A1  - Parlitz, Ulrich
A1  - Sonett, Charles P.
T1  - Testing for nonlinearity in radiocarbon data
N2  - The radiocarbon record that has been extended from 7199 BC to 1891 AD is of fundamental importance to understand century-scale variations of solar activity. We have, therefore, studied how to extract information from dynamic reconstructions of this observational record. Using some rather unusual methods of nonlinear dynamics, we have found that the data are significantly different from linear colored noise and that there is some evidence of nonlinear behavior. The method of recurrence plots exhibits that the grand minima of solar activity are quite different in their recurrence. Most remarkably, it suggests that the recent epoch seems to be similar to the Medieval maximum.
Y1  - 1994
UR  - http://www.agnld.uni-potsdam.de/~shw/Paper/n.ps.gz
SN  - 1023-5809
ER  - 
TY  - JOUR
A1  - Bube, Kevin
A1  - Neto, Camilo Rodrigues
A1  - Donner, Reik Volker
A1  - Schwarz, Udo
A1  - Feudel, Ulrike
T1  - Linear and nonlinear characterization of surfaces from a laser beam melt ablation process
N2  - We apply linear and nonlinear methods to study the properties of surfaces generated by a laser beam melt ablation process. As a result we present a characterization and ordering of the surfaces depending on the adjusted process parameters. Our findings give some insight into the performance of two widely applied multifractal analysis methods-the detrended fluctuation analysis and the wavelet transform modulus maxima method-on short real world data
Y1  - 2006
UR  - http://iopscience.iop.org/0022-3727/
U6  - https://doi.org/10.1088/0022-3727/39/7/011
SN  - 0022-3727
ER  -