Alpha‐particle losses from toroidicity‐induced Alfvén eigenmodes. Part I: Phase‐space topology of energetic particle orbits in tokamak plasma

1992 ◽  
Vol 4 (6) ◽  
pp. 1492-1505 ◽  
Author(s):  
C. T. Hsu ◽  
D. J. Sigmar
Keyword(s):  
Phase Space ◽  
Alpha Particle ◽  
Energetic Particle ◽  
Tokamak Plasma ◽  
Space Topology ◽  
Alfven Eigenmodes ◽  
Particle Orbits ◽  
Phase Space Topology

scholarly journals PC Tendon Damage Detection Based on Change of Phase Space Topology

2018 ◽  
Vol 16 (8) ◽  
pp. 416-428 ◽  
Author(s):  
Porjan Tuttipongsawat ◽  
Eiichi Sasaki ◽  
Keigo Suzuki ◽  
Takuya Kuroda ◽  
Kazuo Takase ◽  
...  
Keyword(s):  
Phase Space ◽  
Damage Detection ◽  
Space Topology ◽  
Phase Space Topology

Structural interrogation using phase space topology of the wind-induced responses

2017 ◽  
Vol 24 (14) ◽  
pp. 3148-3172
Author(s):  
Riya C George ◽  
Sudib K Mishra
Keyword(s):  
Phase Space ◽  
Structural Damage ◽  
Model Building ◽  
Chaotic Signal ◽  
Experimental Investigations ◽  
Damage Scenarios ◽  
Space Topology ◽  
Frame Building ◽  
Low Dimensional ◽  
Phase Space Topology

The applicability of the phase space interrogation (PSI) methodology for structural health monitoring (SHM) is limited on account of the fact that the structure needs to be excited by a low dimensional chaotic signal. The present study demonstrates that the phase space interrogation can still be applied to structures subjected to ambient/moderate wind excitations. Key to this extension is the relative low dimensionality of the wind-induced structural responses, amenable to phase space embedding by virtue of Takens’ embedding theorem. The so-formed pseudo-attractor is shown to sufficiently reflect the changes in system dynamics induced by structural damage(s). A widely employed damage feature, namely, the changes in phase space topology (CPST) is subsequently employed to the reconstructed attractor to link it with the presence, severity, as well as localization of damage(s). The CPST is established as a legitimate damage-sensitive feature by studying its variability with alternative damage scenarios in a multistoried frame building subjected to wind excitations. The performance of the methodology is demonstrated under different degrees of noise contamination in the measured responses as well as varying intensity of wind speed. The statistical robustness of the procedure is also assessed. The numerical findings are supported by the evidence from a limited number of experimental investigations carried out on a model building with inflicted damage scenarios. The wind loadings for the tests are simulated using a wind tunnel testing facility. Finally, a simple analysis is presented that establish the viability of the phase space analysis analytically.

Damage Detection Using Dissimilarity in Phase Space Topology of Dynamic Response of Structure Subjected to Shock Wave Loading

2018 ◽  
Vol 1 (4) ◽  
Author(s):  
Lavish Pamwani ◽  
Amit Shelke
Keyword(s):  
Phase Space ◽  
Damage Detection ◽  
System Analysis ◽  
Singular System ◽  
Second Phase ◽  
Progressive Damage ◽  
Damage State ◽  
Space Topology ◽  
Damage States ◽  
Phase Space Topology

Shockwave is a high pressure and short duration pulse that induce damage and lead to progressive collapse of the structure. The shock load excites high-frequency vibrational modes and causes failure due to large deformation in the structure. Shockwave experiments were conducted by imparting repetitive localized shock loads to create progressive damage states in the structure. Two-phase novel damage detection algorithm is proposed, that quantify and segregate perturbative damage from microscale damage. The first phase performs dimension reduction and damage state segregation using principal component analysis (PCA). In the second phase, the embedding dimension was reduced through empirical mode decomposition (EMD). The embedding parameters were derived using singular system analysis (SSA) and average mutual information function (AMIF). Based, on Takens theorem and embedding parameters, the response was represented in a multidimensional phase space trajectory (PST). The dissimilarity in the multidimensional PST was used to derive the damage sensitive features (DSFs). The DSFs namely: (i) change in phase space topology (CPST) and (ii) Mahalanobis distance between phase space topology (MDPST) are evaluated to quantify progressive damage states. The DSFs are able to quantify the occurrence, magnitude, and localization of progressive damage state in the structure. The proposed algorithm is robust and efficient to detect and quantify the evolution of damage state for extreme loading scenarios.

scholarly journals A Review of Phase Space Topology Methods for Vibration-Based Fault Diagnostics in Nonlinear Systems

2019 ◽  
Vol 8 (3) ◽  
pp. 393-401 ◽  
Author(s):  
T. Haj Mohamad ◽  
Foad Nazari ◽  
C. Nataraj
Keyword(s):  
Phase Space ◽  
Nonlinear Systems ◽  
Dynamic Systems ◽  
Dynamical Behavior ◽  
Fault Diagnostics ◽  
Nonlinear Dynamical ◽  
Space Topology ◽  
Nonlinear Features ◽  
Phase Space Topology

Abstract Background In general, diagnostics can be defined as the procedure of mapping the information obtained in the measurement space to the presence and magnitude of faults in the fault space. These measurements, and especially their nonlinear features, have the potential to be exploited to detect changes in dynamics due to the faults. Purpose We have been developing some interesting techniques for fault diagnostics with gratifying results. Methods These techniques are fundamentally based on extracting appropriate features of nonlinear dynamical behavior of dynamic systems. In particular, this paper provides an overview of a technique we have developed called Phase Space Topology (PST), which has so far displayed remarkable effectiveness in unearthing faults in machinery. Applications to bearing, gear and crack diagnostics are briefly discussed.

Non-universality of anomalous transport

1998 ◽  
Vol 59 (4) ◽  
pp. 671-682 ◽  
Author(s):  
G. M. ZASLAVSKY
Keyword(s):  
Phase Space ◽  
Hamiltonian Systems ◽  
Parameter Space ◽  
Chaotic Dynamics ◽  
Anomalous Transport ◽  
Kinetic Description ◽  
Space Topology ◽  
Low Dimensional ◽  
Phase Space Topology

For low-dimensional Hamiltonian systems with chaotic dynamics, we discuss the differences in the kinetic description, and the necessity of windowing of the time and parameter space, which is imposed by the differences in the phase-space topology and by the stickiness of trajectories at island boundaries.

Mahalanobis distance among the phase portraits as damage feature

2017 ◽  
Vol 17 (4) ◽  
pp. 869-887 ◽  
Author(s):  
Riya C George ◽  
Sudib K Mishra ◽  
Mohit Dwivedi
Keyword(s):  
Phase Space ◽  
Phase Portrait ◽  
Mahalanobis Distance ◽  
Distance Measure ◽  
Dynamic Responses ◽  
Phase Portraits ◽  
Wheel Load ◽  
Space Topology ◽  
Bridge Model ◽  
Phase Space Topology

A number of damage-sensitive features have been proposed based on the damage-induced changes in the phase portrait, reconstructed from the measured dynamic responses of structure. Of a number of alternatives, the change in phase space topology is the most widely acclaimed for assessment of structural health. In this study, a damage feature is proposed by contrasting the damaged phase portrait with the pristine one. The contrast is expressed using the Mahalanobis distance measure, which is remarkably simpler than the change in phase space topology in algorithmic aspect. The feature is referred as Mahalanobis distance among the phase portraits. The performance of the feature is demonstrated by its sensitivity and localization of damage. The noise immunity study reveals reasonable tolerance to the measurement noise. The feature is numerically illustrated on a shear building subjected to Lorentz chaotic excitations and natural wind excitations. The feature is experimentally verified in a railway bridge model subjected to moving wheel load of a model train. The results show the effectiveness of the feature for localizing both the support damage (as in bearing) and damage in the span. Simple analytical argument is also provided to link the phase portrait distortion with the extent and localization of damage(s).

scholarly journals PC Tendon Damage Detection Based on Phase Space Topology Changes in Different Frequency Ranges

2019 ◽  
Vol 17 (8) ◽  
pp. 474-488
Author(s):  
Porjant Tuttipongsawat ◽  
Eiichi Sasaki ◽  
Keigo Suzuki ◽  
Masato Fukuda ◽  
Naoki Kawada ◽  
...  
Keyword(s):  
Phase Space ◽  
Damage Detection ◽  
Space Topology ◽  
Topology Changes ◽  
Phase Space Topology
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