Probability bounds for the system response of non-linear structures

2014 ◽  
pp. 499-502
Author(s):  
R Mullen ◽  
R Muhanna
Keyword(s):  
System Response ◽  
Linear Structures ◽  
Probability Bounds ◽  
Non Linear

scholarly journals Dynamic analysis of space-related linear and non-linear structures

1992 ◽  
Vol 44 (5) ◽  
pp. 1145-1148 ◽  
Author(s):  
P.A. Bosela ◽  
F.J. Shaker ◽  
D.G. Fertis
Keyword(s):  
Dynamic Analysis ◽  
Linear Structures ◽  
Non Linear

Nonlinear Oscillations of an Autoparametrical System With Two Coupled Pendulums

2007 ◽  
Author(s):  
Danuta Sado
Keyword(s):  
Nonlinear Oscillations ◽  
Type System ◽  
Vertical Direction ◽  
Free Vibrations ◽  
System Response ◽  
Main Body ◽  
Bifurcation Diagrams ◽  
Damping Force ◽  
Internal Resonances ◽  
Non Linear

The nonlinear dynamics of a three degree of freedom autoparametrical vibration system with two coupled pendulums in the neighborhood internal and external resonances is presented in this work. It was assumed that the main body is suspended by an element characterized by non-linear elasticity and non-linear damping force and is excited harmonicaly in the vertical direction. The two connected by spring pendulums characterized are mounted to the main body. It is assumed, that the motion of the pendulums are damped by nonlinear resistive forces. Solutions for the system response are presented for specific values of the uncoupled normal frequency ratios and the energy transfer between modes of vibrations is observed. Curves of internal resonances for free vibrations and external resonances for exciting force are shown. In this type system one mode of vibration may excite or damp another one, and except different kinds of periodic vibration there may also appear chaotic vibration. Various techniques, including chaos techniques such as bifurcation diagrams and: time histories, phase plane portraits, power spectral densities, Poincare` maps and exponents of Lyapunov, are used in the identification of the responses. These bifurcation diagrams show many sudden qualitative changes, that is, many bifurcations in the chaotic attractor as well as in the periodic orbits. The results show that the system can exhibit various types of motion, from periodic to quasi-periodic to chaotic, and is sensitive to small changes of the system parameters.

scholarly journals Autonomic nervous system response to remote ischemic conditioning: heart rate variability assessment

2019 ◽  
Vol 19 (1) ◽  
Author(s):  
Daniel Noronha Osório ◽  
Ricardo Viana-Soares ◽  
João Pedro Marto ◽  
Marcelo D. Mendonça ◽  
Hugo P. Silva ◽  
...  
Keyword(s):  
Heart Rate ◽  
Heart Rate Variability ◽  
Nervous System ◽  
Autonomic Nervous System ◽  
Healthy Subjects ◽  
System Response ◽  
Remote Ischemic Conditioning ◽  
Ischemic Conditioning ◽  
Autonomic Nervous ◽  
Non Linear

Abstract Background Remote ischemic conditioning (RIC) is a procedure applied in a limb for triggering endogenous protective pathways in distant organs, namely brain or heart. The underlying mechanisms of RIC are still not fully understood, and it is hypothesized they are mediated either by humoral factors, immune cells and/or the autonomic nervous system. Herein, heart rate variability (HRV) was used to evaluate the electrophysiological processes occurring in the heart during RIC and, in turn to assess the role of autonomic nervous system. Methods Healthy subjects were submitted to RIC protocol and electrocardiography (ECG) was used to evaluate HRV, by assessing the variability of time intervals between two consecutive heart beats. This is a pilot study based on the analysis of 18 ECG from healthy subjects submitted to RIC. HRV was characterized in three domains (time, frequency and non-linear features) that can be correlated with the autonomic nervous system function. Results RIC procedure increased significantly the non-linear parameter SD2, which is associated with long term HRV. This effect was observed in all subjects and in the senior (> 60 years-old) subset analysis. SD2 increase suggests an activation of both parasympathetic and sympathetic nervous system, namely via fast vagal response (parasympathetic) and the slow sympathetic response to the baroreceptors stimulation. Conclusions RIC procedure modulates both parasympathetic and sympathetic autonomic nervous system. Furthermore, this modulation is more pronounced in the senior subset of subjects. Therefore, the autonomic nervous system regulation could be one of the mechanisms for RIC therapeutic effectiveness.

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