Harmonic tremor model during the 2011 Shinmoe-dake eruption, Japan

2020 ◽  
Author(s):  
Minoru Takeo
Keyword(s):  
Global Analysis ◽  
Lumped Parameter Model ◽  
Source Mechanism ◽  
Phase Portraits ◽  
Order System ◽  
Cross Sectional ◽  
Sustained Oscillations ◽  
Harmonic Tremors ◽  
Model Linearization ◽  
Tremor Model

Summary The Shinmoe-dake volcano started with three sub-Plinian eruptions from 26 to 27 January 2011, followed by a magma effusive stage from 28 to 31 January 2011, and Vulcanian eruptions occurred frequently during 1 to 10 February 2011. During the magma effusive and Vulcanian stages, multiple episodes of harmonic tremors were observed at stations near the summit crater. Although harmonic tremors have been observed at various volcanoes worldwide, the source mechanism remains poorly understood. This paper proposes a source model for harmonic tremors, which is composed of a nonlinear viscous fluid flow in a flexible channel. A simple lumped parameter model is used to consider the process. The dynamics are described by a third-order system of ordinary differential equations using model variables for a cross-sectional area of the constricted segment and the fluid velocities in the upstream and downstream tubes. This model produces various kinds of trajectories for self-sustained oscillations that change the reservoir pressure connected on the upstream channel of the model. Linearization analysis around the stationary point and global analysis employing nullcline planes reveal the mechanism of self-sustained oscillations of the system qualitatively. To consider both the frequency peaks of the harmonic tremor and the characteristics of observed phase spectra, the qualitative characteristics of an observed phase portrait are compared to those of a simulated one. This tremor model simulates the frequency peaks and the phase portraits of typical harmonic tremors observed during the 2011 Shinmoe-dake eruption. Because this model involves several geometrical configuration parameters, it has the potential to reveal the source mechanism of various kinds of harmonic tremors.

Public Sector Employment, Quality of Government, and Well-Being: A Global Analysis

2021 ◽  
pp. 223386592110117
Author(s):  
Robert Davidson ◽  
Alexander Pacek ◽  
Benjamin Radcliff
Keyword(s):  
Public Sector ◽  
Global Analysis ◽  
Well Being ◽  
Subjective Well Being ◽  
Cross Sectional ◽  
Political Factors ◽  
The Public ◽  
Employment Quality ◽  
The Impact

While a growing literature within the study of subjective well-being demonstrates the impact of socio-political factors on subjective well-being, scholars have conspicuously failed to consider the role of the size and scope of government as determinants of well-being. Where such studies exist, the focus is largely on the advanced industrial democracies of the Organization for Economic Co-Operation and Development. In this study, we examine the size of the public sector as a determinant of cross-national variation in life satisfaction across a worldwide sample. Our findings strongly suggest that as the public sector grows, subjective well-being increases as well, conditional on the extent of quality of government. Using cross-sectional data on 84 countries, we show this relationship has an independent and separable impact from other economic and political factors.

scholarly journals Global Analysis of a Liénard System with Quadratic Damping

2018 ◽  
Vol 2018 ◽  
pp. 1-9
Author(s):  
Feng Guo
Keyword(s):  
Necessary Conditions ◽  
Global Analysis ◽  
Global Bifurcation ◽  
Phase Portraits ◽  
Liénard System ◽  
Closed Orbits ◽  
Lienard System ◽  
Sufficient And Necessary Conditions ◽  
Global Phase Portrait ◽  
Quadratic Damping

In this paper, the global analysis of a Liénard equation with quadratic damping is studied. There are 22 different global phase portraits in the Poincaré disc. Every global phase portrait is given as well as the complete global bifurcation diagram. Firstly, the equilibria at finite and infinite of the Liénard system are discussed. The properties of the equilibria are studied. Then, the sufficient and necessary conditions of the system with closed orbits are obtained. The degenerate Bogdanov-Takens bifurcation is studied and the bifurcation diagrams of the system are given.

scholarly journals Association between a vegetarian diet and emotional symptoms: a cross-sectional study among adolescents in four developing countries

2018 ◽  
Vol 0 (0) ◽  
Author(s):  
Alejandra Santivañez-Romani ◽  
Valeria Carbajal-Vega ◽  
Reneé Pereyra-Elías
Keyword(s):  
Developing Countries ◽  
Linear Models ◽  
Global Analysis ◽  
Secondary Analysis ◽  
Vegetarian Diet ◽  
Cross Sectional Study ◽  
Self Report ◽  
Sentinel Site ◽  
Emotional Symptoms ◽  
Cross Sectional

AbstractBackgroundStudies assessing the association between vegetarianism and mental health have found divergent results. Evidence from adolescents in developing countries is scarce.ObjectiveTo evaluate the association between a vegetarian diet and emotional symptoms in 15-year-old adolescents from Ethiopia, India, Peru and Vietnam.MethodsA cross-sectional, secondary analysis of the Young Lives cohort study was used. The exposure variable was the self-report of being a vegetarian (yes or no). The outcome was the level of emotional symptoms, numerically evaluated using the score obtained in the subscale “Emotional Symptoms” of the Strengths and Difficulties Questionnaire (SDQ). We calculated crude and adjusted coefficients (β) with 95% confidence intervals (95% CIs), using generalized linear models of the Gaussian family, considering each sentinel site as a cluster. The analysis was stratified by country. Additionally, we made a global analysis including the four countries.ResultsA total of 3484 adolescents were analyzed. The overall prevalence of vegetarianism was 4.4%, but it varied between countries (from 0.4% in Vietnam to 11.5% in India). The average emotional symptoms score was 3.5 [standard deviation (SD) 2.3] points. The scores were not statistically different between vegetarians and non-vegetarians (p > 0.05). In the adjusted analysis, in Vietnam, vegetarians had lower emotional symptoms scores on average than non-vegetarians [β: −1.79; 95% CI: −3.05 to −0.55]. No differences were found neither in the other countries nor in the overall sample.ConclusionThere was no association between a vegetarian diet and emotional symptoms in the analyzed adolescents of four developing countries.

Dynamical Analysis and Circuit Simulation of a New Fractional-Order Hyperchaotic System and Its Discretization

2016 ◽  
Vol 26 (13) ◽  
pp. 1650222 ◽  
Author(s):  
A. M. A. El-Sayed ◽  
A. Elsonbaty ◽  
A. A. Elsadany ◽  
A. E. Matouk
Keyword(s):  
Fractional Order ◽  
Initial Conditions ◽  
Circuit Simulation ◽  
Equilibrium Points ◽  
Dynamical Behavior ◽  
Phase Portraits ◽  
Control Technique ◽  
Order System ◽  
Qualitative Behavior ◽  
Hyperchaotic System

This paper presents an analytical framework to investigate the dynamical behavior of a new fractional-order hyperchaotic circuit system. A sufficient condition for existence, uniqueness and continuous dependence on initial conditions of the solution of the proposed system is derived. The local stability of all the system’s equilibrium points are discussed using fractional Routh–Hurwitz test. Then the analytical conditions for the existence of a pitchfork bifurcation in this system with fractional-order parameter less than 1/3 are provided. Conditions for the existence of Hopf bifurcation in this system are also investigated. The dynamics of discretized form of our fractional-order hyperchaotic system are explored. Chaos control is also achieved in discretized system using delay feedback control technique. The numerical simulation are presented to confirm our theoretical analysis via phase portraits, bifurcation diagrams and Lyapunov exponents. A text encryption algorithm is presented based on the proposed fractional-order system. The results show that the new system exhibits a rich variety of dynamical behaviors such as limit cycles, chaos and transient phenomena where fractional-order derivative represents a key parameter in determining system qualitative behavior.

Multi-Scale Overlapping Domain Decomposition to Consider Local Deformations in the Analysis of Thin-Walled Members

2014 ◽  
Vol 553 ◽  
pp. 667-672
Author(s):  
R. Emre Erkmen
Keyword(s):  
Numerical Technique ◽  
Global Analysis ◽  
Local Deformation ◽  
Local Analysis ◽  
Type Model ◽  
Cross Sectional ◽  
Multi Scale ◽  
Shell Type ◽  
Thin Walled ◽  
The Cross

Thin-walled members that have one dimension relatively large in comparison to the cross-sectional dimensions are usually modelled by using beam-column type finite element formulations. Beam-column elements however, are based on the assumption of rigid cross-section, thus they cannot consider the cross-sectional deformations such as local buckling and only allows considerations of the beam axis behaviour such as flexural or lateral-torsional buckling. Shell-type finite elements can be used to model the structure in order to consider these local deformation effects. Based on the Bridging multi-scale approach, this study proposes a numerical technique that is able to split the global analysis, which is performed by using simple beam-type elements, from the local analysis which is based on more sophisticated shell-type elements. As a result, the proposed multi-scale method allows the usage of shell elements in a local region to incorporate the local deformation effects on the overall behaviour of thin-walled members without necessitating a shell-type model for the whole member.

scholarly journals Multi-Scale Overlapping Domain Decomposition to Consider Elasto-Plastic Local Buckling Effects in the Analysis of Pipes

2017 ◽  
Vol 17 (01) ◽  
pp. 1750015 ◽  
Author(s):  
R. Emre Erkmen ◽  
Magdi Mohareb ◽  
Ashkan Afnani
Keyword(s):  
Domain Decomposition ◽  
Global Analysis ◽  
Computational Cost ◽  
Industrial Applications ◽  
Local Analysis ◽  
Cross Sectional ◽  
Multi Scale ◽  
Shell Type ◽  
Decomposition Procedure ◽  
Beam Type

Elevated pipelines are commonly encountered in petro-chemical and industrial applications. Within these applications, pipelines normally span hundreds of meters and are thus analyzed using one-dimensional (1D) beam-type finite elements when the global behavior of the pipeline is sought at a reasonably low computational cost. Standard beam-type elements, while computationaly economic, are based on the assumption of rigid cross-section. Thus, they are unable to capture the effects of cross-sectional localized deformations. Such effects can be captured through shell-type finite element models. For long pipelines, shell models become prohibitively expensive. Within this context, the present study formulates an efficient numerical modeling which effectively combines the efficiency of beam-type solutions while retaining the accuracy of shell-type solutions. An appealing feature of the model is that it is able to split the global analysis based on simple beam-type elements from the local analysis based on shell-type elements. This is achieved through domain-decomposition procedure within the framework of the Bridging multi-scale method of analysis. Solutions based on the present model are compared to those based on full shell-type analysis. The comparison demonstrates the accuracy and efficiency of the proposed method.

Motorcycle Local Stability Analysis Under Acceleration and Braking by Model Linearization and Eigenproblem Solution

2007 ◽  
Author(s):  
Giuseppe Catania ◽  
Nicolo` Mancinelli
Keyword(s):  
Local Stability ◽  
Graphical Representation ◽  
Virtual Work ◽  
Structural Parameters ◽  
Equilibrium Points ◽  
Oscillatory Behavior ◽  
Operating Conditions ◽  
Lumped Parameter Model ◽  
Symbolic Form ◽  
Model Linearization

A study on the dynamic stability of a motorcycle under severe acceleration and braking conditions is presented. The purpose is to analyze the experimentally observed oscillatory behavior, such as wheel bounce or chatter and rear suspension pitch. This phenomenon greatly affects the handling performance and the safety of sports motorcycles. A plane motion lumped parameter model of the vehicle is defined by the variational virtual work approach. Tire longitudinal forces are modeled using Pacejka’s nonlinear equations for quasi steady states; the kinematical model of the chain drive system is also included. The obtained nonlinear system of second order ordinary differential equations is linearized in symbolic form and transformed into the state space. The same equations of motion are numerically integrated in a commercial multibody code to compute the time histories simulating different maneuvers at quasi constant values of vehicle longitudinal acceleration. Local stability is evaluated via the model eigenvalues that are computed with respect to instantaneous equilibrium points evaluated by numerical integration. Root locus plots are traced to evaluate the graphical representation of damping and frequency associated with previously obtained eigenvalues, under different operating conditions. Coupling of standard key vehicle modes (front/rear wheel hop and suspension pitch) are also visualized by eigenvector animations. The influence of tire characteristics on the damping values of these key motorcycle modes is pointed out. The sensitivity of structural parameters on the stability of the lightly damped and critical modes is then discussed in detail.

scholarly journals Dynamics Analysis and Control of a Five-Term Fractional-Order System

2018 ◽  
Vol 2018 ◽  
pp. 1-10
Author(s):  
Li-xin Yang ◽  
Xiao-jun Liu
Keyword(s):  
Fractional Order ◽  
Equilibrium Points ◽  
Fractional Order System ◽  
Phase Portraits ◽  
Order System ◽  
Bifurcation Diagrams ◽  
Compound Structure ◽  
Dynamical Properties ◽  
The Stability ◽  
And Control

This paper proposes a new fractional-order chaotic system with five terms. Firstly, basic dynamical properties of the fractional-order system are investigated in terms of the stability of equilibrium points, Jacobian matrices theoretically. Furthermore, rich dynamics with interesting characteristics are demonstrated by phase portraits, bifurcation diagrams numerically. Besides, the control problem of the new fractional-order system is discussed via numerical simulations. Our results demonstrate that the new fractional-order system has compound structure.

Forest Cover Change in the Northeastern U.S.

2013 ◽  
Vol 4 (3) ◽  
pp. 1-18
Author(s):  
George C. Bentley ◽  
Robert G. Cromley ◽  
Dean M. Hanink ◽  
C. Patrick Heidkamp
Keyword(s):  
Forest Cover ◽  
Global Analysis ◽  
Local Analysis ◽  
Kuznets Curve ◽  
Forest Cover Change ◽  
Cross Sectional ◽  
Spatial Error ◽  
Explanatory Variables ◽  
Per Capita ◽  
Environmental Good

An analysis of the association of forest cover, treated as an environmental good, and income at the county scale in the Northeastern United States was conducted for 2006. Global analysis using a spatial error regression model indicates an environmental Kuznets curve (EKC) type of relationship, with total forest cover, percent forest cover, and forest cover per capita is better associated with per capita income and is better specified as a polynomial rather than in linear terms. Local analysis, using geographically weighted regression, indicates that sub-regional effects are pronounced, and that conformity to an EKC varies spatially and by forest cover measure. The findings should be interpreted strictly within their context of a cross-sectional analysis and within certain statistical limitations, primarily engendered by multicollinearity of the explanatory variables in the regression models.

Sign in / Sign up

Export Citation Format

Share Document