Perturbation of renewal processes

Perturbation of renewal processes

Date: May 2008
Creator: Akin, Osman Caglar
Description: Renewal theory began development in the early 1940s, as the need for it in the industrial engineering sub-discipline operations research had risen. In time, the theory found applications in many stochastic processes. In this thesis I investigated the effect of seasonal effects on Poisson and non-Poisson renewal processes in the form of perturbations. It was determined that the statistical analysis methods developed at UNT Center for Nonlinear Science can be used to detect the effects of seasonality on the data obtained from Poisson/non-Poisson renewal systems. It is proved that a perturbed Poisson process can serve as a paradigmatic model for a case where seasonality is correlated to the noise and that diffusion entropy method can be utilized in revealing this relation. A renewal model making a connection with the stochastic resonance phenomena is used to analyze a previous neurological experiment, and it was shown that under the effect of a nonlinear perturbation, a non-Poisson system statistics may make a transition and end up in the of Poisson basin of statistics. I determine that nonlinear perturbation of the power index for a complex system will lead to a change in the complexity characteristics of the system, i.e., the system will reach ...
Contributing Partner: UNT Libraries
A dynamic and thermodynamic approach to complexity.

A dynamic and thermodynamic approach to complexity.

Date: August 2003
Creator: Yang, Jin
Description: The problem of establishing the correct approach to complexity is a very hot and crucial issue to which this dissertation gives some contributions. This dissertation considers two main possibilities, one, advocated by Tsallis and co-workers, setting the foundation of complexity on a generalized, non-extensive , form of thermodynamics, and another, proposed by the UNT Center for Nonlinear Science, on complexity as a new condition that, for physical systems, would be equivalent to a state of matter intermediate between dynamics and thermodynamics. In the first part of this dissertation, the concept of Kolmogorov-Sinai entropy is introduced. The Pesin theorem is generalized in the formalism of Tsallis non-extensive thermodynamics. This generalized form of Pesin theorem is used in the study of two major classes of problems, whose prototypes are given by the Manneville and the logistic map respectively. The results of these studies convince us that the approach to complexity must be made along lines different from those of the non-extensive thermodynamics. We have been convinced that the Lévy walk can be used as a prototype model of complexity, as a condition of balance between order and randomness that yields new phenomena such as aging, and multifractality. We reach the conclusions that ...
Contributing Partner: UNT Libraries
Site correlation, anomalous diffusion, and enhancement of the localization length

Site correlation, anomalous diffusion, and enhancement of the localization length

Date: November 1, 1996
Creator: Allegrini, Paolo; Bonci, Luca; Grigolini, Paolo & West, Bruce J.
Description: This article discusses site correlation, anomalous diffusion, and enhancement of localization length.
Contributing Partner: UNT College of Arts and Sciences
Reply to the Comment  "Intercluster correlation in Seismicity" by Helmstetter and Sornette

Reply to the Comment "Intercluster correlation in Seismicity" by Helmstetter and Sornette

Date: September 15, 2003
Creator: Mega, Mirko S.; Allegrini, Paolo; Grigolini, Paolo; Latora, Vito; Palatella, Luigi; Rapisarda, Andrea et al.
Description: This paper is a reply to the comment by Helmstetter and Sornette titled "Intercluster correlation in Seismicity" which addresses an important point in a paper written by the authors that needs to be clarified.
Contributing Partner: UNT College of Arts and Sciences
Mega et al. Reply

Mega et al. Reply

Date: March 26, 2004
Creator: Mega, Mirko S.; Allegrini, Paolo; Grigolini, Paolo; Latora, Vito; Palatella, Luigi; Rapisarda, Andrea et al.
Description: This article is a reply to a comment by A. Helmstetter and D. Sornette about the article 'Power-Law Time Distribution of Large Earthquakes' from 2003.
Contributing Partner: UNT College of Arts and Sciences
Scaling Breakdown: A Signature of Aging

Scaling Breakdown: A Signature of Aging

Date: July 12, 2002
Creator: Allegrini, Paolo; Bellazzini, Jacopo; Bramanti, G.; Ignaccolo, Massimiliano; Grigolini, Paolo & Yang, J.
Description: In this article, the authors prove that the Lévy walk is characterized by bilinear scaling. This effect mirrors the existence of a form of aging that does not require the adoption of nonstationary conditions.
Contributing Partner: UNT College of Arts and Sciences
Long- and Short-Time Analysis of Heartbeat Sequences: Correlation with Mortality Risk in Congestive Heart Failure Patients

Long- and Short-Time Analysis of Heartbeat Sequences: Correlation with Mortality Risk in Congestive Heart Failure Patients

Date: 2003
Creator: Allegrini, Paolo; Balocchi, Rita; Chillemi, Santi; Grigolini, Paolo; Hamilton, P.; Maestri, Roberto et al.
Description: Article discussing long- and short-time analysis of heartbeat sequences and the correlation with mortality risk in congestive heart failure patients.
Contributing Partner: UNT College of Arts and Sciences
Real event detection and the treatment of congestive heart failure: an efficient technique to help cardiologists to make crucial decisions

Real event detection and the treatment of congestive heart failure: an efficient technique to help cardiologists to make crucial decisions

Date: September 2002
Creator: Allegrini, Paolo; Balocchi, Rita; Chillemi, Santi; Grigolini, Paolo; Hamilton, P.; Maestri, Roberto et al.
Description: Paper discussing the treatment of congestive heart failure. Abstract: Using a method of entropic analysis of time series we establish the correlation between heartbeat long-range memory and mortality risk in patients with congestive heart failure.
Contributing Partner: UNT College of Arts and Sciences
Networking of psychophysics, psychology, and neurophysiology

Networking of psychophysics, psychology, and neurophysiology

Date: November 5, 2012
Creator: West, Bruce J. & Grigolini, Paolo
Description: Article discussing the dynamic networking and dynamic networks in complex research on psychophysics, psychology, and neurophysiology.
Contributing Partner: UNT College of Arts and Sciences
Scaling in Non-stationary Time Series II: Teen Birth Phenomenon

Scaling in Non-stationary Time Series II: Teen Birth Phenomenon

Date: February 2, 2008
Creator: Ignaccolo, Massimiliano; Allegrini, Paolo; Grigolini, Paolo; Hamilton, P. & West, Bruce J.
Description: This paper is devoted to the problem of statistical mechanics raised by the analysis of an issue of sociological interest: the teen birth phenomenon.
Contributing Partner: UNT College of Arts and Sciences
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