A brief analysis of the use of non-linear time-frequency filtering for processing ECG signals

Author(s):  
Yeldos A. Altay ◽  
◽  
Artem S. Kremlev
2012 ◽  
Vol 12 (05) ◽  
pp. 1240033 ◽  
Author(s):  
OLIVER FAUST ◽  
V. RAMANAN PRASAD ◽  
G. SWAPNA ◽  
SUBHAGATA CHATTOPADHYAY ◽  
TEIK-CHENG LIM

A large section of the world's population is affected by diabetes mellitus (DM), commonly referred to as "diabetes." Every year, the number of cases of DM is increasing. Diabetes has a strong genetic basis, hence it is very difficult to cure, but can be controlled with medications to prevent subsequent organ damage. Therefore, early diagnosis of diabetes is very important. In this paper, we examine how diabetes affects cardiac health, which is reflected through heart rate variability (HRV), as observed in electrocardiography (ECG) signals. Such signals provide clues for both the presence and severity of diabetes as well as diabetes-induced cardiac impairments. Heart rate (HR) is a non-linear and non-stationary signal. Thus, extracting useful information from HRV signals is a difficult task. We review several sophisticated signal processing and information extraction methods in order to establish measurable relationships between the presence and the extent of diabetes as well as the changes in the HRV signals. Furthermore, we discuss a typical range of values for several statistical, geometric, time domain, frequency domain, time–frequency, and non-linear features for HR signals from 15 normal and 15 diabetic subjects. We found that non-linear analysis is the most suitable approach to capture and analyze the subtle changes in HRV signals caused by diabetes.


2009 ◽  
Vol 413-414 ◽  
pp. 531-538
Author(s):  
Giacomo V. Demarie ◽  
Donato Sabia ◽  
Rosario Ceravolo

The identification of non-linear systems is an important topic in structural health monitoring of structures undergoing non-stationary behavior. In general, a non-linear or hysteretic response is typical for buildings, bridges, dampers and structural elements not only as a consequence of strong excitations (i. e. earthquake), but also for low to medium loading levels, due to the constitutive behavior of structural elements or joints. This paper focuses on the non-linear identification of a RC beam-column joint, modeled as a SDoF system, subjected to non-stationary loading: the technique used entails the definition of proper instantaneous estimators of the system dynamic properties by using a linear time-varying approximation of the actual system dynamics and representing the structural response in the joint time-frequency domain.


Author(s):  
Ray Huffaker ◽  
Marco Bittelli ◽  
Rodolfo Rosa

In the process of data analysis, the investigator is often facing highly-volatile and random-appearing observed data. A vast body of literature shows that the assumption of underlying stochastic processes was not necessarily representing the nature of the processes under investigation and, when other tools were used, deterministic features emerged. Non Linear Time Series Analysis (NLTS) allows researchers to test whether observed volatility conceals systematic non linear behavior, and to rigorously characterize governing dynamics. Behavioral patterns detected by non linear time series analysis, along with scientific principles and other expert information, guide the specification of mechanistic models that serve to explain real-world behavior rather than merely reproducing it. Often there is a misconception regarding the complexity of the level of mathematics needed to understand and utilize the tools of NLTS (for instance Chaos theory). However, mathematics used in NLTS is much simpler than many other subjects of science, such as mathematical topology, relativity or particle physics. For this reason, the tools of NLTS have been confined and utilized mostly in the fields of mathematics and physics. However, many natural phenomena investigated I many fields have been revealing deterministic non linear structures. In this book we aim at presenting the theory and the empirical of NLTS to a broader audience, to make this very powerful area of science available to many scientific areas. This book targets students and professionals in physics, engineering, biology, agriculture, economy and social sciences as a textbook in Nonlinear Time Series Analysis (NLTS) using the R computer language.


2020 ◽  
Author(s):  
E. Priyadarshini ◽  
G. Raj Gayathri ◽  
M. Vidhya ◽  
A. Govindarajan ◽  
Samuel Chakkravarthi

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