RF Nonlinearities in an Analog Optical Link and Their Effect on Radars Carrying Linear and Nonlinear Frequency Modulated Pulses

2012 ◽  
Vol 30 (22) ◽  
pp. 3475-3483 ◽  
Author(s):  
Lior Yaron ◽  
Moshe Tur
Keyword(s):  
Nonlinear Frequency ◽  
Optical Link ◽  
Linear And Nonlinear

Linear and nonlinear frequency shifts in acoustical resonators with varying cross sections

2001 ◽  
Vol 110 (1) ◽  
pp. 109-119 ◽  
Author(s):  
Mark F. Hamilton ◽  
Yurii A. Ilinskii ◽  
Evgenia A. Zabolotskaya
Keyword(s):  
Cross Sections ◽  
Nonlinear Frequency ◽  
Frequency Shifts ◽  
Linear And Nonlinear

scholarly journals Numerical analysis of weak acoustic shocks in aperiodic array of rigid scatterers

2020 ◽  
Author(s):  
Michael Muhlestein ◽  
Carl Hart
Keyword(s):  
Numerical Experiments ◽  
Periodic Structures ◽  
Nonlinear Propagation ◽  
Nonlinear Frequency ◽  
Relative Importance ◽  
Frequency Content ◽  
Rectangular Waveguides ◽  
Initial Shock ◽  
Linear And Nonlinear ◽  
Kzk Equation

Nonlinear propagation of shock waves through periodic structures have the potential to exhibit interesting phenomena. Frequency content of the shock that lies within a bandgap of the periodic structure is strongly attenuated, but nonlinear frequency-frequency interactions pumps energy back into those bands. To investigate the relative importance of these propagation phenomena, numerical experiments using the Khokhlov-Zabolotskaya-Kuznetsov (KZK) equation are carried out. Two-dimensional propagation through a periodic array of rectangular waveguides is per-formed by iteratively using the output of one waveguide as the input for the next waveguide. Comparison of the evolution of the initial shock wave for both the linear and nonlinear cases is presented.

scholarly journals Technique of Definition of Relative Mean Square Assessment of Distortions of the Range of the Signal with Angular Modulation in Digital Synthesizers with Uniform Sampling

2019 ◽  
pp. 1-13
Author(s):  
Dmitry S. Viktorov ◽  
Ekaterina V. Plastinina
Keyword(s):  
Nonlinear Frequency ◽  
Mean Square ◽  
Uniform Sampling ◽  
Linear And Nonlinear ◽  
Definition Of ◽  
Frequency Modulations

In the article the technique allowing to calculate relative mean square assessment of the distortions of a range caused by sampling of a nonquantized signal with angular modulation is considered. For two types of signals, with linear and nonlinear frequency modulations, have calculated the dependences allowing to determine the necessary frequency of sampling by a preset value of relative mean square assessment of distortions of signals

Effect of Negative Stiffness Content on the Periodic Motion of Nonlinearly Coupled Oscillators

2021 ◽  
Vol 16 (11) ◽  
Author(s):  
Mohammad A. Al-Shudeifat
Keyword(s):  
Coupled Oscillators ◽  
Dynamical Behavior ◽  
Negative Stiffness ◽  
Nonlinear Frequency ◽  
Nonlinear Stiffness ◽  
Nonlinear Coupling ◽  
Nonlinear Dynamical ◽  
Wide Range ◽  
Coupling Force ◽  
Linear And Nonlinear

Abstract The linear and nonlinear stiffness coupling forces in dynamical oscillators are usually dominated by positive stiffness components. Therefore, plotting the resultant force in y-axis with respect to the change in displacement in x-axis results in an odd symmetry in the first and third quadrants of the xy-plane. However, the appearance of negative stiffness content in coupling elements between dynamical oscillators generates a force that can be dominated by an odd symmetry in the second and fourth quadrants. The underlying nonlinear dynamical behavior of systems employing this kind of force has not been well-studied in the literature. Accordingly, the considered system here is composed of two linear oscillators that are nonlinearly coupled by a force of which the negative stiffness content is dominant. Therefore, the underlying dynamical behavior of the considered system in physical and dimensionless forms is studied on the frequency-energy plots where many backbone curves of periodic solution have been obtained. It is found that within a wide range of nonlinear frequency levels, the nonlinear coupling force is dominated by a strong negative stiffness content at the obtained frequency-energy plots backbones.

Identification of mechanical properties of adhesive joints using ANN

2017 ◽  
Vol 89 (6) ◽  
pp. 928-935
Author(s):  
Kamran Pazand ◽  
A.S. Nobari
Keyword(s):  
Neural Network ◽  
Mechanical Properties ◽  
Artificial Neural Network ◽  
Natural Frequencies ◽  
Adhesive Joints ◽  
Nonlinear Frequency ◽  
Content Type ◽  
Linear And Nonlinear ◽  
Artificial Neural ◽  
Effective Mechanical Properties

Purpose This paper aims to present a new approach to the fast determination of the effective, dynamic, mechanical properties of an adhesive for linear and nonlinear regions of the adhesive response, for both healthy and damaged states of the bond. Design/methodology/approach The proposed approach is based on the measurement of the linear and nonlinear frequency response function (FRF) of adhesive-bonded structure and using artificial neural network identification technique. For this purpose, linear and nonlinear FRFs are measured for several single-lap joint specimens that are fabricated in healthy and damaged configurations of the bond. The measured FRFs of healthy and damaged specimens are then used to identify the natural frequencies of the specimens. The experimental natural frequencies, in turn, would be used to train artificial neural network (ANN) which would be able to predict the effective Young’s and shear moduli and damping of adhesive in healthy and damaged specimens, for any given excitation level and frequency, within the training domain. Findings Simultaneous identification of the effective mechanical properties of adhesive for linear and nonlinear response regions, as well as healthy and damages states of the adhesive bond. Practical implications The introduced method is effective to model the assembled structures with the viscoelastic adhesive joints, for linear and nonlinear regions. Originality/value A fast methodology, using ANN, for identification the effective mechanical properties of adhesives, compared to other methods for both linear and nonlinear regions.

scholarly journals Interplay of Linear and Nonlinear Localization Mechanisms in Spin-Torque Oscillators with a Field Well

2019 ◽  
Vol 64 (10) ◽  
pp. 947 ◽  
Author(s):  
R. V. Verba
Keyword(s):  
Wave Mode ◽  
Spin Torque ◽  
Nonlinear Frequency ◽  
Magnetization Dynamics ◽  
Nonlinear Localization ◽  
Generation Mode ◽  
Spin Wave Mode ◽  
Linear And Nonlinear ◽  
Generation Power ◽  
Nonlinear Frequency Shift

The magnetization dynamics in a spin-torque oscillator with nonuniform profile of a static magnetic field creating a field well is studied by analytic calculations and numerical simulations. It is demonstrated that, in the case of sufficiently deep and narrow field well, the linear localization in the field well dominates the nonlinear self-localization, despite a negative nonlinear frequency shift. A change of the localization mechanism results in a qualitatively different dependence of the generation power on the driving current. For the dominant linear localization, the soft generation mode is realized, while, for the nonlinear self-localization, we observe a hard mode of auto-oscillator excitation. Simultaneously, a difference in the profiles of the excited spin-wave mode can become evident and distinguishable in experiments only in the case of a nonsymmetric field well.

Comparison of Linear and Nonlinear Frequency Domain Methods for Flutter Analysis

2018 ◽  
Author(s):  
Hans-Peter Kersken ◽  
Graham Ashcroft ◽  
Christian Frey ◽  
Nina Wolfrum ◽  
Oliver Pütz
Keyword(s):  
Frequency Domain ◽  
Harmonic Balance Method ◽  
Frequency Domain Method ◽  
Nonlinear Frequency ◽  
Solution Approach ◽  
Time Solution ◽  
Domain Method ◽  
Frequency Domain Methods ◽  
Flutter Analysis ◽  
Linear And Nonlinear

Both linear and nonlinear frequency domain methods have been applied successfully to the investigation of time-periodic phenomena in turbomachinery. Linear methods allow to perform flutter analysis of turbomachinery blade rows very efficiently. Nonlinear frequency domain method can be applied to flutter analysis as well. If a pseudo-time solution algorithm is employed as a solver the nonlinear frequency domain method takes advantage of the stabilizing effect of the nonlinear coupling of the harmonics. Additionally, it allows studying the influence of nonlinear effects on the flutter stability. A linear GMRes based method and a harmonic balance method using a pseudo-time solution approach are compared with respect to computational efficiency when applied to the flutter analysis of blades of a stationary gas turbine and a low pressure turbine of a jet engine. It is shown that both methods have their merits and limitation depending on the type of problem at hand.

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