TY  - JOUR
A1  - Wessel, Niels
A1  - Voss, Andreas
A1  - Malberg, Hagen
A1  - Ziehmann, Christine
A1  - Voss, Henning U.
A1  - Schirdewan, Alexander
A1  - Meyerfeldt, Udo
A1  - Kurths, Jürgen
T1  - Nonlinear analysis of complex phenomena in cardiological data
N2  - The main intention of this contribution is to discuss different nonlinear approaches to heart rate and blood pressure variability analysis for a better understanding of the cardiovascular regulation. We investigate measures of complexity which are based on symbolic dynamics, renormalised entropy and the finite time growth rates. The dual sequence method to estimate the baroreflex sensitivity and the maximal correlation method to estimate the nonlinear coupling between time series are employed for analysing bivariate data. The latter appears to be a suitable method to estimate the strength of the nonlinear coupling and the coupling direction. Heart rate and blood pressure data from clinical pilot studies and from very large clinical studies are analysed. We demonstrate that parameters from nonlinear dynamics are useful for risk stratification after myocardial infarction, for the prediction of life-threatening cardiac events even in short time series, and for modelling the relationship between heart rate and blood pressure regulation. These findings could be of importance for clinical diagnostics, in algorithms for risk stratification, and for therapeutic and preventive tools of next generation implantable cardioverter defibrillators.
Y1  - 2000
ER  - 
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  - Timmer, Jens
A1  - Kurths, Jürgen
T1  - Nonlinear dynamical system identification from uncertain and indirect measurements
N2  - We review the problem of estimating parameters and unobserved trajectory components from noisy time series measurements of continuous nonlinear dynamical systems. It is first shown that in parameter estimation techniques that do not take the measurement errors explicitly into account, like regression approaches, noisy measurements can produce inaccurate parameter estimates. Another problem is that for chaotic systems the cost functions that have to be minimized to estimate states and parameters are so complex that common optimization routines may fail. We show that the inclusion of information about the time-continuous nature of the underlying trajectories can improve parameter estimation considerably. Two approaches, which take into account both the errors-in-variables problem and the problem of complex cost functions, are described in detail: shooting approaches and recursive estimation techniques. Both are demonstrated on numerical examples
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  - 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  - Voss, Henning U.
A1  - Kurths, Jürgen
T1  - Test for nonlinear dynamical behavior in symbol sequences
Y1  - 1998
ER  - 
TY  - JOUR
A1  - Voss, Henning U.
A1  - Kurths, Jürgen
T1  - Reconstruction of nonlinear time delay models from data by the use of optimal transformations
Y1  - 1997
ER  - 
TY  - JOUR
A1  - Voss, Henning U.
A1  - Kurths, Jürgen
T1  - Reconstruction of nonlinear time-delayed feedback models from optical data
Y1  - 1999
ER  - 
TY  - JOUR
A1  - Voss, Henning U.
A1  - Bünner, M. J.
A1  - Abel, Markus
T1  - Identification of continuous, spatiotemporal systems
Y1  - 1998
UR  - http://www.stat.physik.uni-potsdam.de/~markus/papers/PRE57-2820.pdf
ER  - 
TY  - THES
A1  - Voss, Henning U.
T1  - Nichtlineare statistische Methoden zur Datenanalyse
Y1  - 1998
ER  -