scholarly journals Phase Dynamics in Arrays of Coupled Vortex Spin-Torque Nano-Oscillators

2018 ◽  
Vol 185 ◽  
pp. 03010
Author(s):  
Olga Katkova ◽  
Ansar Safin ◽  
Nikolay Udalov ◽  
Mikhail Kapranov
Keyword(s):  
Complex Networks ◽  
Normal Modes ◽  
Mode Analysis ◽  
Spin Torque ◽  
Hamiltonian Approach ◽  
Phase Dynamics ◽  
Normal Coordinates ◽  
Analysis Technique ◽  
Adjacency Matrices

In this work, the mode analysis technique of complex networks nonlinear selfoscillatory vortex-based spin-torque nano-oscillattors (STNOs) with nonidentity and nonisochrony is developed. We construct adjacency matrices of different type of networks and calculate the normal modes. After the calculation of normal modes we shift to truncated equations for slowly varying amplitudes and phases in the normal coordinates using generalized quasi-Hamiltonian approach. Finally, we present the phase dynamics based on the Kuramotoapproach and compare different networks to the ability of synchronization.

A New Method for Vibration Mode Analysis

2005 ◽  
Author(s):  
David Chelidze ◽  
Wenliang Zhou
Keyword(s):  
Modal Analysis ◽  
A Priori ◽  
Normal Modes ◽  
Orthogonal Decomposition ◽  
Mode Analysis ◽  
Continuous Systems ◽  
Analysis Technique ◽  
Priori Information ◽  
Mathematical Justification ◽  
Proper Orthogonal

In this paper, a new modal analysis method based on a novel multivariate data analysis technique called smooth orthogonal decomposition (SOD) is proposed. The development of the SOD and its main properties are described. The mathematical justification for the application in modal analysis is also provided. The proper orthogonal decomposition (POD) and its application in modal analysis are provided for comparison. Numerical simulations of discrete and continuous systems are used in this comparison. It is demonstrated that the SOD-based analysis overcomes main deficiencies of the POD. The SOD identifies linear normal modes and corresponding frequencies without requiring any a priori information about the distribution of mass in the system.

scholarly journals Normal Mode Analysis as a Routine Part of a Structural Investigation

Molecules ◽  
2019 ◽  
Vol 24 (18) ◽  
pp. 3293 ◽  
Author(s):  
Jacob A. Bauer ◽  
Jelena Pavlović ◽  
Vladena Bauerová-Hlinková
Keyword(s):  
Normal Mode ◽  
Structural Study ◽  
Computer Technology ◽  
Structural Investigation ◽  
Normal Mode Analysis ◽  
Computational Cost ◽  
Normal Modes ◽  
Mode Analysis ◽  
Computationally Expensive ◽  
The Web

Normal mode analysis (NMA) is a technique that can be used to describe the flexible states accessible to a protein about an equilibrium position. These states have been shown repeatedly to have functional significance. NMA is probably the least computationally expensive method for studying the dynamics of macromolecules, and advances in computer technology and algorithms for calculating normal modes over the last 20 years have made it nearly trivial for all but the largest systems. Despite this, it is still uncommon for NMA to be used as a component of the analysis of a structural study. In this review, we will describe NMA, outline its advantages and limitations, explain what can and cannot be learned from it, and address some criticisms and concerns that have been voiced about it. We will then review the most commonly used techniques for reducing the computational cost of this method and identify the web services making use of these methods. We will illustrate several of their possible uses with recent examples from the literature. We conclude by recommending that NMA become one of the standard tools employed in any structural study.

scholarly journals Finite-Time Synchronization of Markovian Jumping Complex Networks with Non-Identical Nodes and Impulsive Effects

Entropy ◽  
2019 ◽  
Vol 21 (8) ◽  
pp. 779
Author(s):  
Tao Chen ◽  
Shiguo Peng ◽  
Zhenhua Zhang
Keyword(s):  
Complex Networks ◽  
Finite Time ◽  
Time Synchronization ◽  
Sufficient Conditions ◽  
Impulsive Effects ◽  
Markovian Jumping ◽  
Complex Dynamic Systems ◽  
Synchronization Problem ◽  
Analysis Technique ◽  
Lyapunov Function Method

In this paper, we investigate the finite-time synchronization problem for a class of Markovian jumping complex networks (MJCNs) with non-identical nodes and impulsive effects. Sufficient conditions for the MJCNs are presented based on an M-matrix technique, Lyapunov function method, stochastic analysis technique, and suitable comparison systems to guarantee finite-time synchronization. At last, numerical examples are exploited to illustrate our theoretical results, and they testify the effectiveness of our results for complex dynamic systems.

On the Importance of Shear Deformation, Rotatory Inertia, and Coriolis Forces in Turbine Blade Vibrations

1986 ◽  
Vol 108 (2) ◽  
pp. 319-324 ◽  
Author(s):  
K. A. Ansari
Keyword(s):  
Shear Deformation ◽  
Turbine Blade ◽  
Normal Modes ◽  
Functional Method ◽  
Lumped Parameter Model ◽  
Rotatory Inertia ◽  
Blade Vibration ◽  
Coriolis Forces ◽  
Analysis Technique ◽  
Blade Vibrations

This paper is concerned with the significance of the effects of shear deformation, rotatory inertia, and Coriolis forces in the analysis of turbine blade vibrations. Since these are quite pronounced at the high frequency ranges encountered in turbine blade vibration problems, they should not be overlooked although their inclusion paves the way for a complicated nonlinear analysis. An approximate analysis technique is presented which involves an application of the stationary functional method using the normal modes of a discretized model. Numerical results for a typical blade are obtained and discussed. An advantage of this analysis as applied to a lumped parameter model is that nonlinear modes higher than the fundamental can also be easily computed and assessed.

Effect of initial stress and rotation on magneto-thermoelastic material with voids and energy dissipation

2017 ◽  
Vol 13 (2) ◽  
pp. 331-346 ◽  
Author(s):  
Mohamed Ibrahim A. Othman ◽  
Mohamed Ibrahim M. Hilal
Keyword(s):  
Laser Pulse ◽  
Initial Stress ◽  
Pulse Heating ◽  
Normal Mode Analysis ◽  
Mode Analysis ◽  
Content Type ◽  
Thermoelastic Material ◽  
Analysis Technique ◽  
Laser Pulse Heating ◽  
Physical Quantities

Purpose The purpose of this paper is to study the effect of rotation and initial stress on magneto-thermoelastic material with voids heated by a laser pulse heating. Design/methodology/approach The analytical method used was the normal mode analysis technique. Findings Numerical results for the physical quantities were presented graphically and analyzed. The graphical results indicate that the effect of rotation, initial stress and magnetic fields are observable physical effects on the thermoelastic material with voids heated by a laser pulse. Comparisons are made with the results in the absence and the presence of the physical operators, also at various times. Originality/value In the present work, the authors shall investigate the effect of the rotation, initial stress, magnetic field and laser pulse on thermoelastic material with voids subjected to a laser pulse heating acting as a thermal shock. A comparison is also made between the two types (types II and III) of Green-Naghdi theory in the absence and the presence of the physical operators. Such problems are very important in many dynamical systems.

Complex Modal Analysis of a Nonmodally Damped Continuous Beam

2015 ◽  
Vol 137 (4) ◽  
Author(s):  
Xing Xing ◽  
Brian F. Feeny
Keyword(s):  
Finite Element ◽  
Eigenvalue Problem ◽  
Normal Modes ◽  
Damping Coefficient ◽  
Mode Analysis ◽  
Element Analysis ◽  
Assumed Mode Method ◽  
State Variable ◽  
Complex Modes ◽  
Assumed Mode

This work represents an investigation of the complex modes of continuous vibration systems with nonmodal damping. As an example, a cantilevered beam with damping at the free end is studied. Assumed modes are applied to discretize the eigenvalue problem in state-variable form and then to obtain estimates of the true complex normal modes and frequencies. The finite element method (FEM) is also used to get the mass, stiffness, and damping matrices and further to solve a state-variable eigenvalue problem. A comparison between the complex modes and eigenvalues obtained from the assumed-mode analysis and the finite element analysis shows that the methods produce consistent results. The convergence behavior when using different assumed mode functions is investigated. The assumed-mode method is then used to study the effects of the end-damping coefficient on the estimated normal modes and modal damping. Most modes remain underdamped regardless of the end-damping coefficient. There is an optimal end-damping coefficient for vibration decay, which correlates with the maximum modal nonsynchronicity.

scholarly journals Frequencies and Normal Modes of Vibration of Benz[a]anthracene Radical Ions

2005 ◽  
Vol 60 (3) ◽  
pp. 158-164
Author(s):  
Rehab M. Kubba ◽  
Raghida I. Al-ani ◽  
Muthana Shanshal
Keyword(s):  
Radical Cation ◽  
Normal Modes ◽  
Equilibrium Geometry ◽  
Vibration Frequencies ◽  
Radical Ions ◽  
Normal Coordinates ◽  
Bond Alternation ◽  
Out Of Plane ◽  
Modes Of Vibration ◽  
Stretching Vibrations

MINDO/3-FORCES calculations were carried out for the radical ions of benz[a]anthracene. Both ions exhibit Cs symmetry with C-C bond alternation in all four rings. The obtained equilibrium geometry was applied for the calculation of all 3N − 6 vibration frequencies of each ion, and for the analysis of their normal coordinates. The so calculated frequencies of the radical cation were close to the experimental frequencies and those of the ab initio calculations. They fall in the ranges νCHstr. (3034 - 3087 cm−1), νCCstr. (1237 - 1609 cm−1), δCH (1142 - 1216 cm−1). Interesting correlations could be obtained for the frequencies of similar vibrations, e. g. νsymCHstr. >νasymCHstr. Exception is the frequency of vibration of CHα in ring A for the radical cation and the same bond in ring D for the radical anion. The vibration frequencies for the CH bonds depend on the σ -electron densities of the corresponding carbon atoms, i. e. νCH.+str. >νCHstr. >νCH.−str., where σ −ρĊ+ >σ −ρC >σ −ρĊ− . For the C-C stretching vibrations the relation ν(C-C)str. >ν(C-C).−str. >ν(C-C).+str. holds, with the exception of the Cβ -Cβ bond, for which the relation ν(C-C)str. >ν(C-C).+str. >ν(C-C).−str. is found. As for the in-plane and out of-plane deformations, the following general correlations δ (CH) >δ (CH).− >δ (CH).+ and γ (CC) >γ (CC).− >γ (CC).+.

scholarly journals ProMode-Oligomer: Database of Normal Mode Analysis in Dihedral Angle Space for a Full-Atom System of Oligomeric Proteins

2012 ◽  
Vol 6 (1) ◽  
pp. 9-19 ◽  
Author(s):  
Hiroshi Wako ◽  
Shigeru Endo
Keyword(s):  
Normal Mode ◽  
Protein Complexes ◽  
Normal Mode Analysis ◽  
Normal Modes ◽  
Point Of View ◽  
Mode Analysis ◽  
Dihedral Angles ◽  
Oligomeric Proteins ◽  
Displacement Vectors ◽  
Atom System

The database ProMode-Oligomer (http://promode.socs.waseda.ac.jp/promode_oligomer) was constructed by collecting normal-mode-analysis (NMA) results for oligomeric proteins including protein-protein complexes. As in the ProMode database developed earlier for monomers and individual subunits of oligomers (Bioinformatics vol. 20, pp. 2035–2043, 2004), NMA was performed for a full-atom system using dihedral angles as independent variables, and we released the results (fluctuations of atoms, fluctuations of dihedral angles, correlations between atomic fluctuations, etc.). The vibrating oligomer is visualized by animation in an interactive molecular viewer for each of the 20 lowest-frequency normal modes. In addition, displacement vectors of constituent atoms for each normal mode were decomposed into two characteristic motions in individual subunits, i.e., internal and external (deformation and rigid-body movements of the individual subunits, respectively), and then the mutual movements of the subunits and the movement of atoms around the interface regions were investigated. These results released in ProMode-Oligomer are useful for characterizing oligomeric proteins from a dynamic point of view. The analyses are illustrated with immunoglobulin light- and heavy-chain variable domains bound to lysozyme and to a 12-residue peptide.

scholarly journals Comparing Data-Driven Methods for Extracting Knowledge from User Generated Content

2019 ◽  
Vol 5 (4) ◽  
pp. 74 ◽  
Author(s):  
Jose Ramon Saura ◽  
Ana Reyes-Menendez ◽  
Ferrão Filipe
Keyword(s):  
Complex Networks ◽  
Latent Dirichlet Allocation ◽  
Knowledge Extraction ◽  
Marketing Strategies ◽  
User Generated Content ◽  
Digital Marketing ◽  
Analysis Technique ◽  
Three Phase ◽  
Networks Analysis ◽  
Visualization Techniques

This study aimed to compare two techniques of business knowledge extraction for the identification of insights related to the improvement of digital marketing strategies on a sample of 15,731 tweets. The sample was extracted from user generated content (UGC) from Twitter using two methods based on knowledge extraction techniques for business. In Method 1, an algorithm to detect communities in complex networks was applied; this algorithm, in which we applied data visualization techniques for complex networks analysis, used the modularity of nodes to discover topics. In Method 2, a three-phase process was developed for knowledge extraction that included the application of a latent Dirichlet allocation (LDA) model, a sentiment analysis (SA) that works with machine learning, and a data text mining (DTM) analysis technique. Finally, we compared the results of each of the two techniques to see whether or not the results yielded by these two methods regarding the analysis of companies’ digital marketing strategies were mutually complementary.

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