TY  - JOUR
A1  - Voss, Henning U.
A1  - Timmer, Jens
A1  - Kurths, Jürgen
T1  - Modeling and identification of nonlinear systems
Y1  - 2004
SN  - 0218-1274
ER  - 
TY  - JOUR
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
N2  - Using a special technique of data analysis, we have found out 34 grand minima of solar activity in a 7,700 years long C14 record. The method used rests on a proper filtering of the C14 record and the extrapolation of verifiable results for the later history back in time. Additionally, we have applied a method of nonlinear dynamics, the recurrence rate, to back up the results. Our findings are not contradictory to the record of grand minima by Eddy, but constitute a considerable extension. Hence, it has become possible to look closer at the validity of models. This way, we have tested esp. the model of Barnes et al. There are hints for that the grand minima might solely be driven by the 209--year period found in the C14 record.
Y1  - 1996
UR  - http://www.agnld.uni-potsdam.de/~shw/Paper/vks.ps.gz
ER  - 
TY  - JOUR
A1  - Timmer, Jens
A1  - Schwarz, Udo
A1  - Voss, Henning U.
A1  - Wardinski, Ingo
A1  - Belloni, Tomaso
A1  - Hasinger, Günther
A1  - VanDerKlis, Michael
A1  - Kurths, Jürgen
T1  - Linear and Nonlinear Time Series Analysis of the Black Hole Candidate Cygnus X-1
N2  - We analyze the variability in the x-ray lightcurves of the black hole candidate Cygnus X-1 by linear and nonlinear time series analysis methods. While a linear model describes the overall second order properties of the observed data well, surrogate data analysis reveals a significant deviation from linearity. We discuss the relation between shot noise models usually applied to analyze these data and linear stochastic autoregressive models. We debate statistical and interpretational issues of surrogate data testing for the present context. Finally, we suggest a combination of tools from linear and nonlinear time series analysis methods as a procedure to test the predictions of astrophysical models on observed data.
Y1  - 2000
UR  - http://pre.aps.org/
ER  -