Dipolar resonance frequency shifts in1H MR spectra of skeletal muscle: Confirmation in rats at 4.7 Tin Vivo and observation of changes postmortem

1997 ◽  
Vol 38 (1) ◽  
pp. 33-39 ◽  
Author(s):  
Vasilis Ntziachristos ◽  
Roland Kreis ◽  
Chris Boesch ◽  
Bjørn Quistorff
Keyword(s):  
Skeletal Muscle ◽  
Resonance Frequency ◽  
Frequency Shifts

scholarly journals Damage Identification in Plate Structures Using Sparse Regularization Based Electromechanical Impedance Technique

Sensors ◽  
2020 ◽  
Vol 20 (24) ◽  
pp. 7069
Author(s):  
Xingyu Fan ◽  
Jun Li
Keyword(s):  
Resonance Frequency ◽  
Structural Damage ◽  
Damage Identification ◽  
Physical Parameters ◽  
Inverse Identification ◽  
Plate Structures ◽  
Frequency Shifts ◽  
Sparse Regularization ◽  
Electromechanical Impedance ◽  
Damage Quantification

This paper proposes a novel structural damage quantification approach using a sparse regularization based electromechanical impedance (EMI) technique. Minor structural damage in plate structures by using the measurement of only a single surface bonded lead zirconate titanate piezoelectric (PZT) transducer was quantified. To overcome the limitations of using model-based EMI based methods in damage detection of complex or relatively large-scale structures, a three-dimensional finite element model for simulating the PZT–structure interaction is developed and calibrated with experimental results. Based on the sensitivities of the resonance frequency shifts of the impedance responses with respect to the physical parameters of plate structures, sparse regularization was applied to conduct the undetermined inverse identification of structural damage. The difference between the measured and analytically obtained impedance responses was calculated and used for identification. In this study, only a limited number of the resonance frequency shifts were obtained from the selected frequency range for damage identification of plate structures with numerous elements. The results demonstrate a better performance than those from the conventional Tikhonov regularization based methods in conducting inverse identification for damage quantification. Experimental studies on an aluminum plate were conducted to investigate the effectiveness and accuracy of the proposed approach. To test the robustness of the proposed approach, the identification results of a plate structure under varying temperature conditions are also presented.

Nonlinear resonance frequency shifts in acoustical resonators with varying cross sections.

2008 ◽  
Vol 124 (4) ◽  
pp. 2491-2491 ◽  
Author(s):  
Yurii A. Ilinskii ◽  
Mark F. Hamilton ◽  
Evgenia A. Zabolotskaya
Keyword(s):  
Resonance Frequency ◽  
Cross Sections ◽  
Nonlinear Resonance ◽  
Frequency Shifts
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