Strongly nonlinear behavior of granular chains and granular composites

2008 ◽  
Vol 123 (5) ◽  
pp. 3271-3271 ◽  
Author(s):  
Vitali F. Nesterenko ◽  
Eric B. Herbold ◽  
David J. Benson ◽  
Jeonghoon Kim ◽  
Chiara Daraio
Keyword(s):  
Nonlinear Behavior ◽  
Strongly Nonlinear ◽  
Granular Chains ◽  
Granular Composites

Nonlinear behavior for periodically excited brushless motor

2019 ◽  
Vol 38 (2) ◽  
pp. 522-535
Author(s):  
Jianzhe Huang ◽  
Xingzhong Xiong
Keyword(s):  
Working Condition ◽  
Analytic Solution ◽  
Nonlinear Behavior ◽  
Analytic Solutions ◽  
Strong Nonlinearity ◽  
Periodic Motions ◽  
Content Type ◽  
Strongly Nonlinear ◽  
Brushless Motor ◽  
Analytic Expressions

Purpose Due to the coupling between the direct-axis current, quadrature-axis current and rotor speed, the dynamic response could be strongly nonlinear. Besides, if the working condition is severe, the loading is no longer constant and multiple harmonics could be introduced. In this paper, the periodic motions for brushless motor will be solved, and accurate analytic solution will be obtained through the proposed method. The purpose of this study is to provide accurate analytic solution of periodic motions for brushless motor with fluctuated loading, which is a dynamic system with strong nonlinearity. Design/methodology/approach A newly developed semi-analytic algorithm called discrete implicit maps is used to give analytic solutions for both stable and unstable motions for such a motor. Findings The accurate analytic expressions for stable and unstable periodic motions have been obtained. For unstable motion, it can stay on the unstable orbit for many periods without any controller. Through bifurcation analysis, the parameter sensitivity has been obtained which can be a suggestion for design and operation. Originality/value This paper provides all possible analytical solutions for period-1 motion as well as the unstable motions in a range of system parameters. It offers a chance to control the unstable motion for such a motor.

Wave-Based Control of a Nonlinear Flexible System

2006 ◽  
Author(s):  
William J. O’Connor ◽  
Francisco Ramos ◽  
Vicente Feliu
Keyword(s):  
Control Strategies ◽  
System Modeling ◽  
Nonlinear Behavior ◽  
Effective Control ◽  
Space Structures ◽  
Large Space ◽  
Flexible System ◽  
Strongly Nonlinear ◽  
Mechanical Waves ◽  
Actuator System

The motivation for this work is the control of flexible mechanical systems, such as long, light robot arms, gantry cranes, and large space structures, with an actuator at one end and a free boundary at the other. Very effective control strategies have recently been developed which are based on interpreting the actuator motion as launching mechanical “waves” (propagating motion) into the flexible system while absorbing returning “waves”. These control systems are robust to system changes and to actuator limitations. They are generic, require very little system modeling, need only local sensing, and are computationally light and easy to implement. In a flexible arm, when elastic deflections are large, frequently there is strongly nonlinear behavior. This paper investigates how such nonlinearities affect the wave-based control strategy. In summary, the news is good. It is found that errors arise only when trajectories are very demanding, and even then the errors are small. Some strategies for correcting these errors are explained: addition of a linear element at the actuator-system interface, error correction by second manoeuver, and redefinition of the waves in a less-than-optimal way. The paper presents these ideas and illustrates them with numerical simulations.

scholarly journals Nonlinear Heat Transport in Superlattices with Mobile Defects

Entropy ◽  
2019 ◽  
Vol 21 (12) ◽  
pp. 1200 ◽  
Author(s):  
David Jou ◽  
Liliana Restuccia
Keyword(s):  
Thermal Conductivity ◽  
Heat Flux ◽  
Heat Conduction ◽  
Thermal Resistance ◽  
Heat Transport ◽  
Concentration Dependence ◽  
Transport Coefficients ◽  
Nonlinear Behavior ◽  
Strongly Nonlinear

We consider heat conduction in a superlattice with mobile defects, which reduce the thermal conductivity of the material. If the defects may be dragged by the heat flux, and if they are stopped at the interfaces of the superlattice, it is seen that the effective thermal resistance of the layers will depend on the heat flux. Thus, the concentration dependence of the transport coefficients plus the mobility of the defects lead to a strongly nonlinear behavior of heat transport, which may be used in some cases as a basis for thermal transistors.

scholarly journals Adaptation in cone photoreceptors contributes to an unexpected insensitivity of On parasol retinal ganglion cells to spatial structure in natural images

2021 ◽  
Author(s):  
Zhou Yu ◽  
Maxwell H Turner ◽  
Fred Rieke
Keyword(s):  
Spatial Structure ◽  
Retinal Ganglion Cells ◽  
Neural Circuits ◽  
Ganglion Cells ◽  
Nonlinear Behavior ◽  
Building Blocks ◽  
Retinal Ganglion ◽  
Cone Photoreceptors ◽  
Strongly Nonlinear ◽  
Visual Inputs

Neural circuits are constructed from nonlinear building blocks, and not surprisingly overall circuit behavior is often strongly nonlinear. But neural circuits can also behave near linearly, and some circuits shift from linear to nonlinear behavior depending on stimulus conditions. Such control of the linearity or nonlinearity of circuit behavior is fundamental to neural computation. Here we study a surprising stimulus dependence of the responses of On (but not Off) parasol retinal ganglion cells: these cells respond nonlinearly to spatial structure in temporally-modulated grating stimuli but linearly to spatial structure in flashed gratings and natural visual inputs. We show that this unexpected response linearity can be explained by a shift in the balance of excitatory and inhibitory synaptic inputs that originates at least in part from adaptation in the cone photoreceptors. More generally, this highlights how subtle asymmetries in signaling - here in the cone signals - can qualitatively alter circuit computation.

Scattering of Solitary Waves and Excitation of Transient Breathers in Granular Media by Light Intruders and No Precompression

2011 ◽  
Vol 79 (1) ◽  
Author(s):  
Yuli Starosvetsky ◽  
K. R. Jayaprakash ◽  
Alexander F. Vakakis
Keyword(s):  
Granular Medium ◽  
Granular Media ◽  
Multiple Scale ◽  
Hertzian Contact ◽  
Reduced Models ◽  
Strongly Nonlinear ◽  
Granular Chains ◽  
Low Amplitude ◽  
Excitation Conditions ◽  
Nonlinear Regimes

We analyze the dynamics of strongly nonlinear granular chains of beads in Hertzian contact with light intruders. We show that the interactions of the light intruders with solitary pulses propagating through the granular medium can be approximately studied by reduced models of the intruders with only their neighboring beads under similar excitation conditions. Studying the reduced models, we identify weakly and strongly nonlinear regimes in the dynamics, depending on the degree of compression between beads and on the occurrence of separation between neighboring beads leading to collisions. We analyze weakly and strongly nonlinear oscillatory regimes of the intruder dynamics by multiple-scale analysis, and by applying special nonsmooth coordinate transformations. When separation between beads occurs, localized transient breathers are excited, corresponding to repeated collisions of an intruder with its neighbors. This leads to high-frequency scattering energy, and to radiation of energy in the granular medium in the form of low-amplitude slowly modulated oscillatory pulses. We find that repeated excitation of localized transient breathers by an array of periodically placed intruders can result in drastic reduction of the amplitude of a solitary wave propagating through the granular medium. This indicates that this type of granular media can be designed as effective shock attenuators.

Seismic Performance of a Historical Apartment Building Using a Barcelona Model (BM) Adapted for Masonry Walls

2017 ◽  
Vol 747 ◽  
pp. 646-652 ◽  
Author(s):  
Izabela J. Drygala ◽  
Joanna M. Dulinska ◽  
Łukasz Bednarz ◽  
Jerzy Jasienko
Keyword(s):  
Seismic Event ◽  
Three Dimensional ◽  
Nonlinear Behavior ◽  
Fe Model ◽  
Inelastic Behavior ◽  
Apartment Building ◽  
Strongly Nonlinear ◽  
Seismic Shock ◽  
Historical Masonry ◽  
Standard Software

The main objective of this study was to examine the dynamic response of a masonry monumental apartment building subjected to a strong seismic event. A three-dimensional FE model of the building was prepared with the ABAQUS Standard software program. Three components of the registered seismic event were applied as seismic excitation acting in three directions. To represent the inelastic behavior of the masonry elements of the structure under the earthquake, a Barcelona Model (BM) was assumed as a constitutive model for the masonry elements. The analysis proved that strongly nonlinear behavior of the masonry monumental apartment building was observed under the strong seismic shock. The plastic strains as well as the tensile damage (cracking) were obtained in some zones of the walls of the structure after seismic shock. In the paper authors also discussed the methodology for strengthening and structural health monitoring dedicated for historical masonry structures.

scholarly journals Strongly nonlinear waves in locally resonant granular chains

Nonlinearity ◽  
2016 ◽  
Vol 29 (11) ◽  
pp. 3496-3527 ◽  
Author(s):  
Lifeng Liu ◽  
Guillaume James ◽  
Panayotis Kevrekidis ◽  
Anna Vainchtein
Keyword(s):  
Nonlinear Waves ◽  
Strongly Nonlinear ◽  
Granular Chains

scholarly journals Observation of Two-Wave Structure in Strongly Nonlinear Dissipative Granular Chains

2007 ◽  
Vol 98 (16) ◽  
Author(s):  
Alexandre Rosas ◽  
Aldo H. Romero ◽  
Vitali F. Nesterenko ◽  
Katja Lindenberg
Keyword(s):  
Wave Structure ◽  
Strongly Nonlinear ◽  
Granular Chains

Computer Simulation of Stick-Slip Friction in Mechanical Dynamic Systems

1985 ◽  
Vol 107 (1) ◽  
pp. 100-103 ◽  
Author(s):  
Dean Karnopp
Keyword(s):  
Computer Simulation ◽  
Dynamic Systems ◽  
Nonlinear Behavior ◽  
Stick Slip ◽  
Strongly Nonlinear ◽  
Zero Velocity ◽  
Straightforward Method ◽  
Performance Limitations ◽  
Almost All

Stick-slip friction is present to some degree in almost all actuators and mechanisms and is often responsible for performance limitations. Simulation of stick-slip friction is difficult because of strongly nonlinear behavior in the vicinity of zero velocity. A straightforward method for representing and simulating friction effects is presented. True zero velocity sticking is represented without equation reformulation or the introduction of numerical stiffness problems.

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