Nonlinear Behaviors of Round Corner Steel Box-Section Piers

2018 ◽  
pp. 365-372 ◽  
Author(s):  
Mitao Ohga ◽  
Shinichiro Takemura ◽  
Satoru Imamura
Keyword(s):  
Box Section ◽  
Nonlinear Behaviors

Convergence in per capita carbon footprint and ecological footprint for G7 countries: Evidence from panel Fourier threshold unit root test

2021 ◽  
pp. 0958305X2110114
Author(s):  
Veli Yilanci ◽  
Muhammed Sehid Gorus ◽  
Sakiru Adebola Solarin
Keyword(s):  
Unit Root ◽  
Structural Breaks ◽  
Structural Changes ◽  
Unit Root Test ◽  
G7 Countries ◽  
Convergence Hypothesis ◽  
International Climate ◽  
Per Capita ◽  
Nonlinear Behaviors ◽  
Nonlinear Unit Root Tests

This paper aims to explore the convergence of per capita carbon and ecological footprints in G7 countries during 1961–2016. For this purpose, we propose a new unit root test in the panel setting–the panel Fourier threshold unit root test. This test takes into consideration both multiple smooth structural changes and nonlinearity. According to the literature, the power of the nonlinear unit root tests is reduced in the case of ignoring structural breaks. Therefore, we expect to get more reliable empirical findings by utilizing this methodology. The empirical results of this paper show that these series have nonlinear behaviors for the period 1961–2016. Furthermore, they demonstrate that the absolute convergence hypothesis is valid in G7 countries for both regimes. Thus, governments can conduct common environmental policies, including international climate summits and agreements, instead of national-based policies to mitigate environmental deterioration in their countries.

scholarly journals Period-doubling bifurcation analysis and chaos control for load torque using FLC

2021 ◽  
Author(s):  
Eman Moustafa ◽  
Abdel-Azem Sobaih ◽  
Belal Abozalam ◽  
Amged Sayed A. Mahmoud
Keyword(s):  
Floquet Theory ◽  
Chaos Control ◽  
Fuzzy Logic Controller ◽  
Chaotic Behavior ◽  
Period Doubling ◽  
Parameter Variation ◽  
Period Doubling Bifurcation ◽  
Load Torque ◽  
Nonlinear Behaviors ◽  
Scientific Fields

AbstractChaotic phenomena are observed in several practical and scientific fields; however, the chaos is harmful to systems as they can lead them to be unstable. Consequently, the purpose of this study is to analyze the bifurcation of permanent magnet direct current (PMDC) motor and develop a controller that can suppress chaotic behavior resulted from parameter variation such as the loading effect. The nonlinear behaviors of PMDC motors were investigated by time-domain waveform, phase portrait, and Floquet theory. By varying the load torque, a period-doubling bifurcation appeared which in turn led to chaotic behavior in the system. So, a fuzzy logic controller and developing the Floquet theory techniques are applied to eliminate the bifurcation and the chaos effects. The controller is used to enhance the performance of the system by getting a faster response without overshoot or oscillation, moreover, tends to reduce the steady-state error while maintaining its stability. The simulation results emphasize that fuzzy control provides better performance than that obtained from the other controller.

Study of nonlinear behaviors of geological materials

2011 ◽  
Vol 6 (5) ◽  
pp. 1613-1620
Author(s):  
Tsun-Hui Huang ◽  
Shyue-Cheng Yang ◽  
Chiou-Fen Shieh
Keyword(s):  
Geological Materials ◽  
Nonlinear Behaviors

Bifurcation Trees of Periodic Motions to Chaos in a Parametric, Quadratic Nonlinear Oscillator

2014 ◽  
Vol 24 (05) ◽  
pp. 1450075 ◽  
Author(s):  
Albert C. J. Luo ◽  
Bo Yu
Keyword(s):  
Fourier Series ◽  
Nonlinear Systems ◽  
Analytical Solutions ◽  
Nonlinear Oscillator ◽  
Series Solution ◽  
Parametric Oscillator ◽  
Periodic Motions ◽  
Parametric Oscillators ◽  
Harmonic Term ◽  
Nonlinear Behaviors

In this paper, bifurcation trees of periodic motions to chaos in a parametric oscillator with quadratic nonlinearity are investigated analytically as one of the simplest parametric oscillators. The analytical solutions of periodic motions in such a parametric oscillator are determined through the finite Fourier series, and the corresponding stability and bifurcation analyses for periodic motions are completed. Nonlinear behaviors of such periodic motions are characterized through frequency–amplitude curves of each harmonic term in the finite Fourier series solution. From bifurcation analysis of the analytical solutions, the bifurcation trees of periodic motion to chaos are obtained analytically, and numerical illustrations of periodic motions are presented through phase trajectories and analytical spectrum. This investigation shows period-1 motions exist in parametric nonlinear systems and the corresponding bifurcation trees to chaos exist as well.

Three-Dimensional Seismic Response Analysis of Buried Continuous or Jointed Pipelines

1987 ◽  
Vol 109 (1) ◽  
pp. 80-87 ◽  
Author(s):  
S. Takada ◽  
K. Tanabe
Keyword(s):  
Seismic Behavior ◽  
Ground Motions ◽  
Three Dimensional ◽  
Response Analysis ◽  
Ground Deformations ◽  
Pipe Systems ◽  
Experimental Values ◽  
Earthquake Response Analysis ◽  
Nonlinear Behaviors ◽  
Torsional Properties

This paper presents a three-dimensional quasi-static analysis of continuous or jointed pipelines. Transfer Matrix Method was applied to the analysis providing for nonlinear behaviors of joints and soil frictions. An improved computer program ERAUL-II (Earthquake Response Analysis of Underground Lifelines-II) was developed for numerical computations. First, numerical response analyses were carried out for three-dimensional pipe systems with steel or cast iron pipe materials subject to large ground deformations or seismic ground motions. Analytical results show that torsional properties of pipes are also important factors for seismic behavior, which cannot be known by two-dimensional analyses. Second, experimental test data of three-dimensional steel pipe systems were simulated by using the ERAUL-II program. Simulated results agree well with the experimental values.

Experimental investigation of tsunami bore-induced forces and pressures on skewed box section bridges

2021 ◽  
Vol 224 ◽  
pp. 108730
Author(s):  
Farzad Farvizi ◽  
Bruce W. Melville ◽  
Asaad Y. Shamseldin ◽  
Seyedreza Shafiei ◽  
Ehsan Hendi
Keyword(s):  
Experimental Investigation ◽  
Box Section

Nonlinear dynamics of a spur gear pair with tooth root crack based on an amplitude modulation function

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Nan Gao ◽  
Shiyu Wang ◽  
Muhammad Asad Ur Rehman Bajwa
Keyword(s):  
Nonlinear Dynamics ◽  
Amplitude Modulation ◽  
Spur Gear ◽  
Dynamic Mesh ◽  
Gear Pair ◽  
Mesh Stiffness ◽  
Chaotic Motions ◽  
Content Type ◽  
Modulation Function ◽  
Nonlinear Behaviors

PurposeGear transmissions are widely utilized in practice. This paper aims to uncouple the crack feature from the cracked time-varying mesh stiffness (TVMS) and investigate the effects of the crack on the nonlinear dynamics of a spur gear pair.Design/methodology/approachAn approximate method to simulate the cracked TVMS is proposed by using an amplitude modulation function. The ratio of mesh stiffness loss is introduced to estimate the TVMS with different crack depths and angles. The dynamic responses are obtained by solving a torsional model which takes the non-loaded static transmission error, the backlash and the cracked TVMS into account. By using the bifurcation diagram, the largest Lyapunov exponent (LLE) and dynamic mesh force, the influences of crack on nonlinear behaviors are examined. The dynamic characteristics are identified from the phase diagram, Poincaré map, dynamic mesh force, time series and FFT spectra.FindingsThe comparison between the healthy and cracked gear pairs indicates that the crack affects the system motions, such as the obvious changes of impact force and unpredictable instability. Besides, the additive and difference combination frequencies can be found in periodic-1 and -2 motions, but they are covered in periodic-3 and chaotic motions. Deeper crack is an important determinant of the nonlinear behaviors at a higher speed.Originality/valueThe research provides an interesting perspective on cracked TVMS and reveals the connection between crack and nonlinear behaviors of the gear pairs.

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