To see the other types of publications on this topic, follow the link: Force coupled oscillator.

Journal articles on the topic 'Force coupled oscillator'

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles

Select a source type:

Consult the top 50 journal articles for your research on the topic 'Force coupled oscillator.'

Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.

You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.

Browse journal articles on a wide variety of disciplines and organise your bibliography correctly.

1

Jose, Sebin, Goutam Chakraborty, and Ranjan Bhattacharyya. "Force transmissibility characteristics of a pseudoelastic oscillator." Journal of Intelligent Material Systems and Structures 31, no. 3 (2019): 349–63. http://dx.doi.org/10.1177/1045389x19888736.

Full text
Abstract:
The force transmissibility characteristics of a passive vibration isolator in the form of shape memory alloy bar are investigated. The shape memory alloy bar, together with a rigid mass, constitutes a single-degree-of-freedom system. The force isolation ability of the oscillator is evaluated for both isothermal and convective environmental conditions. The transmissibility curve of an isothermal pseudoelastic oscillator displays single and double jumps depending upon the forcing amplitude. The shape memory alloy oscillator with coupled thermomechanical behaviour depends on the cooling rate near resonant frequencies. Increased cooling rate reduces both peak amplitude and the resonant frequency of the transmissibility curve. The force isolation provided by shape memory alloy oscillator is independent of the operating conditions.
APA, Harvard, Vancouver, ISO, and other styles
2

Kang, Jaeyoung. "Parametric study on friction-induced coupled oscillator." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 222, no. 8 (2008): 1381–87. http://dx.doi.org/10.1243/09544062jmes987.

Full text
Abstract:
This paper investigates the dynamic instability of a sliding oscillator subjected to non-linear friction force. The dynamic instability is determined by the system eigenvalues of the linearized equation of motion. Mode-coupling type instability and negative slope type instability are considered to be the mechanism generating the friction-induced vibration. The mode coupling between two vibration modes strongly depends on the system parameters such as the spring inclination angle. The conditions for the divergence and dynamic instability are presented in the mathematical form. The damping coefficient of an inclined support arm is seen to determine the modal damping separation influencing on the dynamic instability.
APA, Harvard, Vancouver, ISO, and other styles
3

Kim, Seunghwan, Seon Hee Park, and Chang Su Ryu. "Noise-induced transitions in coupled oscillator systems with a pinning force." Physical Review E 54, no. 6 (1996): 6042–52. http://dx.doi.org/10.1103/physreve.54.6042.

Full text
APA, Harvard, Vancouver, ISO, and other styles
4

Warminski, J., and K. Kecik. "Autoparametric vibrations of a nonlinear system with pendulum." Mathematical Problems in Engineering 2006 (2006): 1–19. http://dx.doi.org/10.1155/mpe/2006/80705.

Full text
Abstract:
Vibrations of a nonlinear oscillator with an attached pendulum, excited by movement of its point of suspension, have been analysed in the paper. The derived differential equations of motion show that the system is strongly nonlinear and the motions of both subsystems, the pendulum and the oscillator, are strongly coupled by inertial terms, leading to the so-called autoparametric vibrations. It has been found that the motion of the oscillator, forced by an external harmonic force, has been dynamically eliminated by the pendulum oscillations. Influence of a nonlinear spring on the vibration absorption near the main parametric resonance region has been carried out analytically, whereas the transition from regular to chaotic vibrations has been presented by using numerical methods. A transmission force on the foundation for regular and chaotic vibrations is presented as well.
APA, Harvard, Vancouver, ISO, and other styles
5

Huang, Z. S., G. L. Gebber, S. Zhong, and S. M. Barman. "Forced oscillations in sympathetic nerve discharge." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 263, no. 3 (1992): R564—R571. http://dx.doi.org/10.1152/ajpregu.1992.263.3.r564.

Full text
Abstract:
Periodic electrical stimulation of the medullary raphe or lateral tegmental field in baroreceptor-denervated cats was used to force the central systems responsible for the 10-Hz and 2- to 6-Hz rhythms in post-ganglionic sympathetic nerve discharge (SND). The 10-Hz rhythm in SND could be entrained either to the frequency of medullary stimulation or to harmonics of the stimulus frequency. The harmonic of the stimulus frequency to which the 10-Hz rhythm was entrained in one postganglionic nerve could be different from that in another nerve. On this basis, we propose that the circuits responsible for the 10-Hz rhythms in SND may be modeled as a system of coupled nonlinear oscillators, each of which either influences one postganglionic nerve or nonuniformly affects different postganglionic nerves. The relatively wide band 2- to 6-Hz component in SND could be forced into a stable oscillatory state by medullary stimulation at frequencies between 3 and 5 Hz. This observation is consistent with the view that the 2- to 6-Hz component reflects the complex behavior of a nonlinear oscillator rather than the output of a physiological noise generator.
APA, Harvard, Vancouver, ISO, and other styles
6

Xia, Ji, Fuyin Wang, Chunyan Cao, Zhengliang Hu, Heng Yang, and Shuidong Xiong. "A Nanoscale Photonic Crystal Cavity Optomechanical System for Ultrasensitive Motion Sensing." Crystals 11, no. 5 (2021): 462. http://dx.doi.org/10.3390/cryst11050462.

Full text
Abstract:
Optomechanical nanocavities open a new hybrid platform such that the interaction between an optical cavity and mechanical oscillator can be achieved on a nanophotonic scale. Owing to attractive advantages such as ultrasmall mass, high optical quality, small mode volume and flexible mechanics, a pair of coupled photonic crystal nanobeam (PCN) cavities are utilized in this paper to establish an optomechanical nanosystem, thus enabling strong optomechanical coupling effects. In coupled PCN cavities, one nanobeam with a mass meff~3 pg works as an in-plane movable mechanical oscillator at a fundamental frequency of πΩm/2π=4.148 MHz. The other nanobeam couples light to excite optical fundamental supermodes at 1542.858 and 1554.464 nm with a Qo larger than 4 × 104. Because of the optomechanical backaction arising from an optical force, abundant optomechanical phenomena in the unresolved sideband are observed in the movable nanobeam. Moreover, benefiting from the in-plane movement of the flexible nanobeam, we achieved a maximum displacement of the movable nanobeam as 1468 fm/Hz1/2. These characteristics indicate that this optomechanical nanocavity is capable of ultrasensitive motion measurements.
APA, Harvard, Vancouver, ISO, and other styles
7

Chen, Yonghong, C. A. Tan, and L. A. Bergman. "Effects of Boundary Flexibility on the Vibration of a Continuum With a Moving Oscillator." Journal of Vibration and Acoustics 124, no. 4 (2002): 552–60. http://dx.doi.org/10.1115/1.1505029.

Full text
Abstract:
In this paper, the problem of an oscillator traversing an elastically supported continuum is studied. The flexibility in the boundaries of the continuum is modeled by linear, transverse springs. The response of the continuum and the dynamic interaction force between the moving oscillator and the continuum are evaluated by an eigenfunction expansion series. To circumvent convergence difficulties associated with the jump in the shear force due to the moving interaction force, an improved series expansion employing the static Green’s function is derived. The coupled governing equations of motion are solved numerically and results are obtained to examine the effects of the boundary flexibility on the response, the dynamic interaction force, the shear force spatial and temporal distributions, as well as the convergence properties of the expansion series. It is found that high order modal terms contribute significantly to the shear force expansion series in the elastically supported model. The presence of large amplitude and high frequency components in the shear force is critical in understanding the cumulative fatigue failure of the structure. A useful and compact formula estimating the value of the support stiffness above which a boundary may be modeled as simply supported is also derived.
APA, Harvard, Vancouver, ISO, and other styles
8

Bocko, Mark F., and Roberto Onofrio. "On the measurement of a weak classical force coupled to a harmonic oscillator: experimental progress." Reviews of Modern Physics 68, no. 3 (1996): 755–99. http://dx.doi.org/10.1103/revmodphys.68.755.

Full text
APA, Harvard, Vancouver, ISO, and other styles
9

Gendelman, O. V., and Yu Starosvetsky. "Quasi-Periodic Response Regimes of Linear Oscillator Coupled to Nonlinear Energy Sink Under Periodic Forcing." Journal of Applied Mechanics 74, no. 2 (2006): 325–31. http://dx.doi.org/10.1115/1.2198546.

Full text
Abstract:
Quasi-periodic response of a linear oscillator attached to nonlinear energy sink with relatively small mass under external sinusoidal forcing in a vicinity of main (1:1) resonance is studied analytically and numerically. It is shown that the quasi-periodic response is exhibited in well-defined amplitude-frequency range of the external force. Two qualitatively different regimes of the quasi-periodic response are revealed. The first appears as a result of linear instability of the steady-state regime of the oscillations. The second one occurs due to interaction of the dynamical flow with invariant manifold of damped-forced nonlinear normal mode of the system, resulting in hysteretic motion of the flow in the vicinity of this mode. Parameters of external forcing giving rise to the quasi-periodic response are predicted by means of simplified analytic model. The model also allows predicting that the stable quasi-periodic regimes appear for certain range of damping coefficient. All findings of the simplified analytic model are verified numerically and considerable agreement is observed.
APA, Harvard, Vancouver, ISO, and other styles
10

Hamed, Y. S., Ali Kandil, and José Tenreiro Machado. "Utilizing Macro Fiber Composite to Control Rotating Blade Vibrations." Symmetry 12, no. 12 (2020): 1984. http://dx.doi.org/10.3390/sym12121984.

Full text
Abstract:
This work applies an active control algorithm, using a macro fiber composite (MFC) to mitigate the unwanted vibrations of a rotating blade. The algorithm is a second-order oscillator, having the positive displacement signal of the blade for input and the suitable control force to actuate the blade for output. This oscillator is linearly coupled with the blade, having in mind that their natural frequencies must be in the vicinity of each other. The rotating blade is modeled by representing two vibrational directions that are linearly coupled. An asymptotic analysis is considered to understand the resulting nonlinear phenomena. Several responses are included to portray the dynamical behavior of the system under control. From the results, we observe the asymmetry between the blade’s vibrational directions. Moreover, a verification is included for comparing the analytical and numerical results.
APA, Harvard, Vancouver, ISO, and other styles
11

Körner, Julia, Christopher F. Reiche, Bernd Büchner, Thomas Mühl, and Gerald Gerlach. "Employing electro-mechanical analogies for co-resonantly coupled cantilever sensors." Journal of Sensors and Sensor Systems 5, no. 2 (2016): 245–59. http://dx.doi.org/10.5194/jsss-5-245-2016.

Full text
Abstract:
Abstract. Understanding the behaviour of mechanical systems can be facilitated and improved by employing electro-mechanical analogies. These analogies enable the use of network analysis tools as well as purely analytical treatment of the mechanical system translated into an electric circuit. Recently, we developed a novel kind of sensor set-up based on two coupled cantilever beams with matched resonance frequencies (co-resonant coupling) and possible applications in magnetic force microscopy and cantilever magnetometry. In order to analyse the sensor's behaviour in detail, we describe it as an electric circuit model. Starting from a simplified coupled harmonic oscillator model with neglected damping, we gradually increase the complexity of the system by adding damping and interaction elements. For each stage, various features of the coupled system are discussed and compared to measured data obtained with a co-resonant sensor. Furthermore, we show that the circuit model can be used to derive sensor parameters which are essential for the evaluation of measured data. Finally, the much more complex circuit representation of a bending beam is discussed, revealing that the simplified circuit model of a coupled harmonic oscillator is a very good representation of the sensor system.
APA, Harvard, Vancouver, ISO, and other styles
12

PHILLIPSON, PAUL E., and PETER SCHUSTER. "BISTABILITY OF HARMONICALLY FORCED RELAXATION OSCILLATIONS." International Journal of Bifurcation and Chaos 12, no. 06 (2002): 1295–307. http://dx.doi.org/10.1142/s0218127402005078.

Full text
Abstract:
Relaxation oscillations appear in processes which involve transitions between two states characterized by fast and slow time scales. When a relaxation oscillator is coupled to an external periodic force its entrainment by the force results in a response which can include multiple periodicities and bistability. The prototype of these behaviors is the harmonically driven van der Pol equation which displays regions in the parameter space of the driving force amplitude where stable orbits of periods 2n ± 1 coexist, flanked by regions of periods 2n + 1 and 2n - 1. The parameter regions of such bistable orbits are derived analytically for the closely related harmonically driven Stoker–Haag piecewise discontinuous equation. The results are valid over most of the control parameter space of the system. Also considered are the reasons for the more complicated dynamics featuring regions of high multiple periodicity which appear like noise between ordered periodic regions. Since this system mimics in detail the less analytically tractable forced van der Pol equation, the results suggest extensions to situations where forced relaxation oscillations are a component of the operating mechanisms.
APA, Harvard, Vancouver, ISO, and other styles
13

GANDHIMATHI, V. M., S. RAJASEKAR, and J. KURTHS. "EFFECTS OF THE SHAPE OF PERIODIC FORCES ON STOCHASTIC RESONANCE." International Journal of Bifurcation and Chaos 18, no. 07 (2008): 2073–88. http://dx.doi.org/10.1142/s0218127408021579.

Full text
Abstract:
We study the influence of the shapes of three different external periodic forces on the stochastic resonance phenomenon in multiple potential well systems with Gaussian noise. We consider as external periodic forces the sine wave, the modulus of sine wave and the rectified sine wave. The systems of our interest are two coupled overdamped anharmonic oscillators and the Duffing oscillator. For fixed values of the parameters, when the intensity D of the external noise is varied, the systems with these periodic forces separately are found to exhibit stochastic resonance. Certain similarities and differences are found in the characteristics of these statistical measures such as signal-to-noise ratio (SNR), response amplitude (Q), time series plot, mean residence time τMR in the potential wells and the distribution P of the normalized residence time for these different forces. Especially, the time series plot at the maximum SNR shows an almost periodic switching between the potential wells for the sine force which is not observed for the other two forces. In the noise-induced intermittent dynamics, τMR is the same in different wells for the sine force, whereas it is different in different wells for the other two forces for each value of the noise intensity D. Further, variation of τMR with D, the value of τMR at the resonance and the distribution P show different features for the different types of forces. We present a detailed comparative study and explanation for the similarities and differences observed in the stochastic resonance dynamics.
APA, Harvard, Vancouver, ISO, and other styles
14

Schneider, Edwin K., and Meizhu Fan. "Observed Decadal North Atlantic Tripole SST Variability. Part II: Diagnosis of Mechanisms." Journal of the Atmospheric Sciences 69, no. 1 (2012): 51–64. http://dx.doi.org/10.1175/jas-d-11-019.1.

Full text
Abstract:
Abstract In Part I of this study, the atmospheric weather noise for 1951–2000 was inferred from an atmospheric analysis in conjunction with SST-forced AGCM simulations and used to force interactive ensemble coupled GCM simulations of the North Atlantic SST variability. Here, results from those calculations are used in conjunction with a simple stochastically forced coupled model of the decadal time scale North Atlantic tripole SST variability to examine the mechanisms associated with the tripole SST variability. The diagnosed tripole variability is found to be characterized by damped, delayed oscillator dynamics, similar to what has been found by other investigators. However, major differences here, affecting the signs of two of the crucial parameters of the simple model, are that the atmospheric heat flux feedback damps the tripole pattern and that a counterclockwise intergyre gyre-like circulation enhances the tripole pattern. Delayed oscillator dynamics are still obtained because the sign of the dynamically important parameter, proportional to the product of these two parameters, is unchanged. Another difference with regard to the dynamical processes included in the simple model is that the major contribution to the ocean’s dynamical heat flux response to the weather noise wind stress is through a delayed modulation of the mean gyres, rather than from the simultaneous intergyre gyre response. The power spectrum of a revised simple model forced by white noise has a less prominent decadal peak using the parameter values and dynamics diagnosed here than in previous investigations. Decadal time scale retrospective predictions made with this version of the simple model are no better than persistence.
APA, Harvard, Vancouver, ISO, and other styles
15

Helm, J. F., W. J. Dodds, J. Christensen, and S. K. Sarna. "Control mechanism of spontaneous in vitro contractions of the opossum sphincter of Oddi." American Journal of Physiology-Gastrointestinal and Liver Physiology 249, no. 5 (1985): G572—G579. http://dx.doi.org/10.1152/ajpgi.1985.249.5.g572.

Full text
Abstract:
We evaluated the control mechanism of peristaltic contractions in the opossum sphincter of Oddi (SO) by means of an in vitro preparation. At each of four sites spaced uniformly along the sphincter segment, a force transducer recorded contractions while a monopolar electrode recorded myoelectric activity. Spontaneous myoelectric and contractile activity occurred in 15 of the 20 intact SO specimens studied. Electrical recordings showed characteristic control waves and response activity. Each control wave was invariably accompanied by a phasic contraction, irrespective of whether or not response activity was superimposed on the control wave. The predominant motor activity of the SO was antegrade peristalsis. Retrograde peristalsis occurred when antegrade peristalsis failed to traverse the entire sphincter. Spontaneous SO phasic contractions were not antagonized by tetrodotoxin. Muscle rings sectioned from the SO exhibited spontaneous phasic contractions with a proximal-to-distal gradient of intrinsic contraction frequencies. We conclude that a) the frequency of SO phasic contractions is determined by control wave frequency, b) spontaneous SO peristalsis is myogenic in origin and may be modeled by a linear array of bidirectionally coupled relaxation oscillators, c) the predominance of antegrade peristalsis may be explained by a high-frequency oscillator in the proximal SO that drives the slower, more distal oscillators, d) retrograde peristalsis is initiated by an ectopic oscillator in the distal SO when antegrade contractions fail to propagate the entire length of the SO, and e) ectopic SO contractions can propagate retrograde when the more proximal oscillators are not in their absolutely refractory state.
APA, Harvard, Vancouver, ISO, and other styles
16

Wang, Chunzai. "A review of ENSO theories." National Science Review 5, no. 6 (2018): 813–25. http://dx.doi.org/10.1093/nsr/nwy104.

Full text
Abstract:
Abstract The El Niño and the Southern Oscillation (ENSO) occurrence can be usually explained by two views of (i) a self-sustained oscillatory mode and (ii) a stable mode interacting with high-frequency forcing such as westerly wind bursts and Madden-Julian Oscillation events. The positive ocean–atmosphere feedback in the tropical Pacific hypothesized by Bjerknes leads the ENSO event to a mature phase. After ENSO event matures, negative feedbacks are needed to cease the ENSO anomaly growth. Four negative feedbacks have been proposed: (i) reflected Kelvin waves at the ocean western boundary, (ii) a discharge process due to Sverdrup transport, (iii) western-Pacific wind-forced Kelvin waves and (iv) anomalous zonal advections and wave reflection at the ocean eastern boundary. These four ENSO mechanisms are respectively called the delayed oscillator, the recharge–discharge oscillator, the western-Pacific oscillator and the advective–reflective oscillator. The unified oscillator is developed by including all ENSO mechanisms, i.e. all four ENSO oscillators are special cases of the unified oscillator. The tropical Pacific Ocean and atmosphere interaction can also induce coupled slow westward- and eastward-propagating modes. An advantage of the coupled slow modes is that they can be used to explain the propagating property of interannual anomalies, whereas the oscillatory modes produce a standing oscillation. The research community has recently paid attention to different types of ENSO events by focusing on the central-Pacific El Niño. All of the ENSO mechanisms may work for the central-Pacific El Niño events, with an addition that the central-Pacific El Niño may be related to forcing or processes in the extra-tropical Pacific.
APA, Harvard, Vancouver, ISO, and other styles
17

Carboni, Biagio, Walter Lacarbonara, Patrick T. Brewick, and Sami F. Masri. "Dynamical response identification of a class of nonlinear hysteretic systems." Journal of Intelligent Material Systems and Structures 29, no. 13 (2018): 2795–810. http://dx.doi.org/10.1177/1045389x18778792.

Full text
Abstract:
The experimental dynamical response of three types of nonlinear hysteretic systems is identified employing phenomenological models togheter with the Differential Evolutionary algorithm. The mass–spring–damper system is characterized by hysteretic restoring forces provided by assemblies of shape memory and steel wire ropes subject to flexure or coupled states of tension and flexure. The energy dissipation due to phase transformations and inter-wire friction and the stretching-induced geometric nonlinearities give rise to different shapes of hysteresis cycles. The mechanical device subject to strong seismic excitations is investigated in its ultimate limit state whereby inelastic strains are induced in the steel wires together with a global nonsymmetric response of the system. The targeted dynamical characterization of the hysteretic oscillator up to its ultimate limit state has a special meaning when the device is employed in the field of vibration control. The dynamical response is identified exploiting the measurements of the oscillating mass relative displacement and inertia force that must be balanced, at each time instant, by the overall restoring forces provided by the mechanism. The restoring force is assumed to be the sum of different contributions such as a cubic nonsymmetric elastic force and a nonsymmetric hysteretic force modeled according to a modified version of the Bouc–Wen model. The parameters are identified minimizing the difference between the numerical and the experimental restoring force histories. High levels of accuracy are achieved in the identification with mean square errors lower than 2%.
APA, Harvard, Vancouver, ISO, and other styles
18

Avitabile, D., M. Homer, A. R. Champneys, J. C. Jackson, and D. Robert. "Mathematical modelling of the active hearing process in mosquitoes." Journal of The Royal Society Interface 7, no. 42 (2009): 105–22. http://dx.doi.org/10.1098/rsif.2009.0091.

Full text
Abstract:
Insects have evolved diverse and delicate morphological structures in order to capture the inherently low energy of a propagating sound wave. In mosquitoes, the capture of acoustic energy and its transduction into neuronal signals are assisted by the active mechanical participation of the scolopidia. We propose a simple microscopic mechanistic model of the active amplification in the mosquito species Toxorhynchites brevipalpis . The model is based on the description of the antenna as a forced-damped oscillator coupled to a set of active threads (ensembles of scolopidia) that provide an impulsive force when they twitch. This twitching is in turn controlled by channels that are opened and closed if the antennal oscillation reaches a critical amplitude. The model matches both qualitatively and quantitatively with recent experiments: spontaneous oscillations, nonlinear amplification, hysteresis, 2 : 1 resonances, frequency response and gain loss owing to hypoxia. The numerical simulations presented here also generate new hypotheses. In particular, the model seems to indicate that scolopidia located towards the tip of Johnston's organ are responsible for the entrainment of the other scolopidia and that they give the largest contribution to the mechanical amplification.
APA, Harvard, Vancouver, ISO, and other styles
19

Dodla, Ramana, and Charles J. Wilson. "Effect of Phase Response Curve Shape and Synaptic Driving Force on Synchronization of Coupled Neuronal Oscillators." Neural Computation 29, no. 7 (2017): 1769–814. http://dx.doi.org/10.1162/neco_a_00978.

Full text
Abstract:
The role of the phase response curve (PRC) shape on the synchrony of synaptically coupled oscillating neurons is examined. If the PRC is independent of the phase, because of the synaptic form of the coupling, synchrony is found to be stable for both excitatory and inhibitory coupling at all rates, whereas the antisynchrony becomes stable at low rates. A faster synaptic rise helps extend the stability of antisynchrony to higher rates. If the PRC is not constant but has a profile like that of a leaky integrate-and-fire model, then, in contrast to the earlier reports that did not include the voltage effects, mutual excitation could lead to stable synchrony provided the synaptic reversal potential is below the voltage level the neuron would have reached in the absence of the interaction and threshold reset. This level is controlled by the applied current and the leakage parameters. Such synchrony is contingent on significant phase response (that would result, for example, by a sharp PRC jump) occurring during the synaptic rising phase. The rising phase, however, does not contribute significantly if it occurs before the voltage spike reaches its peak. Then a stable near-synchronous state can still exist between type 1 PRC neurons if the PRC shows a left skewness in its shape. These results are examined comprehensively using perfect integrate-and-fire, leaky integrate-and-fire, and skewed PRC shapes under the assumption of the weakly coupled oscillator theory applied to synaptically coupled neuron models.
APA, Harvard, Vancouver, ISO, and other styles
20

Abundis-Fong, H. F., J. Enríquez-Zárate, A. Cabrera-Amado, and G. Silva-Navarro. "Optimum Design of a Nonlinear Vibration Absorber Coupled to a Resonant Oscillator: A Case Study." Shock and Vibration 2018 (2018): 1–11. http://dx.doi.org/10.1155/2018/2107607.

Full text
Abstract:
This paper presents the optimal design of a passive autoparametric cantilever beam vibration absorber for a linear mass-spring-damper system subject to harmonic external force. The design of the autoparametric vibration absorber is obtained by using an approximation of the nonlinear frequency response function, computed via the multiple scales method. Based on the solution given by the perturbation method mentioned above, a static optimization problem is formulated in order to determine the optimum parameters (mass and length) of the nonlinear absorber which minimizes the steady state amplitude of the primary mass under resonant conditions; then, a PZT actuator is cemented to the base of the beam, so the nonlinear absorber is made active, thus enabling the possibility of controlling the effective stiffness associated with the passive absorber and, as a consequence, the implementation of an active vibration control scheme able to preserve, as possible, the autoparametric interaction as well as to compensate varying excitation frequencies and parametric uncertainty. Finally, some simulations and experimental results are included to validate and illustrate the dynamic performance of the overall system.
APA, Harvard, Vancouver, ISO, and other styles
21

Castro, A. S. M. de, and V. V. Dodonov. "Quantum coupled oscillators versus forced oscillator." Journal of Optics B: Quantum and Semiclassical Optics 3, no. 4 (2001): 228–37. http://dx.doi.org/10.1088/1464-4266/3/4/306.

Full text
APA, Harvard, Vancouver, ISO, and other styles
22

PHILLIPSON, PAUL E., and PETER SCHUSTER. "AN ANALYTIC PICTURE OF NEURON OSCILLATIONS." International Journal of Bifurcation and Chaos 14, no. 05 (2004): 1539–48. http://dx.doi.org/10.1142/s0218127404010151.

Full text
Abstract:
Current induced oscillations of a space clamped neuron action potential demonstrates a bifurcation scenario originally encapsulated by the four-dimensional Hodgkin–Huxley equations. These oscillations were subsequently described by the two-dimensional FitzHugh–Nagumo Equations in close agreement with the Hodgkin–Huxley theory. It is shown that the FitzHugh–Nagumo equations can to close approximation be reduced to a generalized van der Pol oscillator externally driven by the current. The current functions as an external constant force driving the action potential. As a consequence approximate analytic expressions are derived which predict the bifurcation scenario, the amplitudes of the oscillations and the oscillation periods in terms of the current and the physiological constants of the FitzHugh–Nagumo model. A second reduction permits explicit analytic solution and results in a spiking model which can be multiply coupled and extended to include the dynamics of phase locking, entrainment and chaos characteristic of time-dependent synaptic inputs.
APA, Harvard, Vancouver, ISO, and other styles
23

Brumley, Douglas R., Marco Polin, Timothy J. Pedley, and Raymond E. Goldstein. "Metachronal waves in the flagellar beating of Volvox and their hydrodynamic origin." Journal of The Royal Society Interface 12, no. 108 (2015): 20141358. http://dx.doi.org/10.1098/rsif.2014.1358.

Full text
Abstract:
Groups of eukaryotic cilia and flagella are capable of coordinating their beating over large scales, routinely exhibiting collective dynamics in the form of metachronal waves. The origin of this behaviour—possibly influenced by both mechanical interactions and direct biological regulation—is poorly understood, in large part due to a lack of quantitative experimental studies. Here we characterize in detail flagellar coordination on the surface of the multicellular alga Volvox carteri , an emerging model organism for flagellar dynamics. Our studies reveal for the first time that the average metachronal coordination observed is punctuated by periodic phase defects during which synchrony is partial and limited to specific groups of cells. A minimal model of hydrodynamically coupled oscillators can reproduce semi-quantitatively the characteristics of the average metachronal dynamics, and the emergence of defects. We systematically study the model's behaviour by assessing the effect of changing intrinsic rotor characteristics, including oscillator stiffness and the nature of their internal driving force, as well as their geometric properties and spatial arrangement. Our results suggest that metachronal coordination follows from deformations in the oscillators' limit cycles induced by hydrodynamic stresses, and that defects result from sufficiently steep local biases in the oscillators' intrinsic frequencies. Additionally, we find that random variations in the intrinsic rotor frequencies increase the robustness of the average properties of the emergent metachronal waves.
APA, Harvard, Vancouver, ISO, and other styles
24

Westre, S. G., X. Liu, J. D. Getty, and P. B. Kelly. "A force field analysis of the methyl radicalX̃ 2A‘2state stretching potential using the local mode—coupled Morse oscillator model." Journal of Chemical Physics 95, no. 12 (1991): 8793–802. http://dx.doi.org/10.1063/1.461812.

Full text
APA, Harvard, Vancouver, ISO, and other styles
25

Tsiatas, George C., and Dimitra A. Karatzia. "Reliability analysis of the hysteretic nonlinear energy sink in shock mitigation considering uncertainties." Journal of Vibration and Control 26, no. 23-24 (2020): 2261–73. http://dx.doi.org/10.1177/1077546320919304.

Full text
Abstract:
The reliability of the hysteretic nonlinear energy sink in shock mitigation is investigated herein. The hysteretic nonlinear energy sink is a passive vibration control device which is coupled to a primary linear oscillator. Apart from its small mass and a nonlinear elastic spring of the Duffing oscillator, it also comprises a purely hysteretic and a linear elastic spring of potentially negative stiffness. The Bouc–Wen model is used to describe the force produced by both the purely hysteretic and linear elastic springs. The hysteretic nonlinear energy sink protects the primary system through the energy pumping mechanism which transfers energy from the primary system and dissipates it in the hysteretic nonlinear energy sink. Three nonlinear equations of motion describe the resulting two-degree-of-freedom system response. The parameters of the system to be considered as uncertain are the natural frequency of the primary system and the hysteretic nonlinear energy sink linear elastic spring, which follow a normal distribution. A reliability analysis is then performed to evaluate the robustness of the coupled system in the presence of uncertainty. Specifically, the reliability index is calculated based on first passage probabilities of distinct dissipation energy level crossings using the Monte Carlo method. Several examples are examined considering various levels of initial input energy, and useful conclusions are drawn concerning the influence of uncertainty in the system robustness.
APA, Harvard, Vancouver, ISO, and other styles
26

Birnholtz, Ofek, Shahar Hadar, and Barak Kol. "Radiation reaction at the level of the action." International Journal of Modern Physics A 29, no. 24 (2014): 1450132. http://dx.doi.org/10.1142/s0217751x14501322.

Full text
Abstract:
The aim of this paper is to highlight a recently proposed method for the treatment of classical radiative effects, in particular radiation reaction, via effective field theory methods. We emphasize important features of the method and in particular the doubling of fields. We apply the method to two simple systems: a mass–rope system and an electromagnetic charge-field system. For the mass–rope system in 1 + 1 dimensions we derive a double-field effective action for the mass which describes a damped harmonic oscillator. For the EM charge-field system, i.e. the system of an accelerating electric charge in 3 + 1 dimensions, we show a reduction to a 1 + 1 dimensions radial system of an electric dipole source coupled to an electric dipole field (analogous to the mass coupled to the rope). For this system we derive a double-field effective action and reproduce in an analogous way the leading part of the Abraham–Lorentz–Dirac force.
APA, Harvard, Vancouver, ISO, and other styles
27

DANA, SYAMAL KUMAR, BRAJENDRA K. SINGH, SATYABRATA CHAKRABORTY, et al. "MULTISCROLL IN COUPLED DOUBLE SCROLL TYPE OSCILLATORS." International Journal of Bifurcation and Chaos 18, no. 10 (2008): 2965–80. http://dx.doi.org/10.1142/s0218127408022196.

Full text
Abstract:
A unidirectional coupling scheme is investigated in double scroll type chaotic oscillators that reveal interesting multiscroll dynamics. Instead of using self-oscillatory systems, in this scheme, double scroll chaos from one oscillator is forced into another similar oscillator in a resting state. This coupling scheme is explored in the Chua oscillator, a modified Chua oscillator and the Lorenz oscillator. We have modified the Chua oscillator by simply changing its piecewise linear function slightly, thereby deriving a new 3-scroll attractor. We have observed 4-scroll, 6-scroll attractors in the driven Chua oscillator and the modified Chua oscillator respectively in an intermittency regime of weaker coupling. We have extended the coupling scheme to the Lorenz system when even more interesting multiscroll dynamics (3-, 4-, 5-, 6-scroll) is observed with decreasing coupling strength. It appears as if a hidden multiscroll structure unfolds with weakening coupling interactions. One after another, additional scrolls appear in the driven Lorenz system when the coupling strength is gradually decreased in the weaker coupling regime. The origin of such multiscroll dynamics is explained using eigenvalue analysis and a bifurcation diagram. A schematic diagram of the multiscroll trajectories is presented to further elucidate the evolution of the scrolls. Experimental evidence is also presented using the Chua circuit and an electronic analog of the Lorenz system.
APA, Harvard, Vancouver, ISO, and other styles
28

WESTRE, S. G., X. LIU, J. D. GETTY, and P. B. KELLY. "ChemInform Abstract: A Force Field Analysis of the Methyl Radical X2A′′ 2 State Stretching Potential Using the Local Mode-Coupled Morse Oscillator Model." ChemInform 23, no. 19 (2010): no. http://dx.doi.org/10.1002/chin.199219039.

Full text
APA, Harvard, Vancouver, ISO, and other styles
29

Granada, Adrián E., Trinitat Cambras, Antoni Díez-Noguera, and Hanspeter Herzel. "Circadian desynchronization." Interface Focus 1, no. 1 (2010): 153–66. http://dx.doi.org/10.1098/rsfs.2010.0002.

Full text
Abstract:
The suprachiasmatic nucleus (SCN) coordinates via multiple outputs physiological and behavioural circadian rhythms. The SCN is composed of a heterogeneous network of coupled oscillators that entrain to the daily light–dark cycles. Outside the physiological entrainment range, rich locomotor patterns of desynchronized rhythms are observed. Previous studies interpreted these results as the output of different SCN neural subpopulations. We find, however, that even a single periodically driven oscillator can induce such complex desynchronized locomotor patterns. Using signal analysis, we show how the observed patterns can be consistently clustered into two generic oscillatory interaction groups: modulation and superposition. In seven of 17 rats undergoing forced desynchronization, we find a theoretically predicted third spectral component. Combining signal analysis with the theory of coupled oscillators, we provide a framework for the study of circadian desynchronization.
APA, Harvard, Vancouver, ISO, and other styles
30

Bell, Andrew, and Hero P. Wit. "The vibrating reed frequency meter: digital investigation of an early cochlear model." PeerJ 3 (October 13, 2015): e1333. http://dx.doi.org/10.7717/peerj.1333.

Full text
Abstract:
The vibrating reed frequency meter, originally employed by Békésy and later by Wilson as a cochlear model, uses a set of tuned reeds to represent the cochlea’s graded bank of resonant elements and an elastic band threaded between them to provide nearest-neighbour coupling. Here the system, constructed of 21 reeds progressively tuned from 45 to 55 Hz, is simulated numerically as an elastically coupled bank of passive harmonic oscillators driven simultaneously by an external sinusoidal force. To uncover more detail, simulations were extended to 201 oscillators covering the range 1–2 kHz. Calculations mirror the results reported by Wilson and show expected characteristics such as traveling waves, phase plateaus, and a response with a broad peak at a forcing frequency just above the natural frequency. The system also displays additional fine-grain features that resemble those which have only recently been recognised in the cochlea. Thus, detailed analysis brings to light a secondary peak beyond the main peak, a set of closely spaced low-amplitude ripples, rapid rotation of phase as the driving frequency is swept, frequency plateaus, clustering, and waxing and waning of impulse responses. Further investigation shows that each reed’s vibrations are strongly localised, with small energy flow along the chain. The distinctive set of equally spaced ripples is an inherent feature which is found to be largely independent of boundary conditions. Although the vibrating reed model is functionally different to the standard transmission line, its cochlea-like properties make it an intriguing local oscillator model whose relevance to cochlear mechanics needs further investigation.
APA, Harvard, Vancouver, ISO, and other styles
31

Manna, Raj Kumar, Oleg E. Shklyaev, and Anna C. Balazs. "Chemical pumps and flexible sheets spontaneously form self-regulating oscillators in solution." Proceedings of the National Academy of Sciences 118, no. 12 (2021): e2022987118. http://dx.doi.org/10.1073/pnas.2022987118.

Full text
Abstract:
The synchronization of self-oscillating systems is vital to various biological functions, from the coordinated contraction of heart muscle to the self-organization of slime molds. Through modeling, we design bioinspired materials systems that spontaneously form shape-changing self-oscillators, which communicate to synchronize both their temporal and spatial behavior. Here, catalytic reactions at the bottom of a fluid-filled chamber and on mobile, flexible sheets generate the energy to “pump” the surrounding fluid, which also transports the immersed sheets. The sheets exert a force on the fluid that modifies the flow, which in turn affects the shape and movement of the flexible sheets. This feedback enables a single coated (active) and even an uncoated (passive) sheet to undergo self-oscillation, displaying different oscillatory modes with increases in the catalytic reaction rate. Two sheets (active or passive) introduce excluded volume, steric interactions. This distinctive combination of the hydrodynamic, fluid–structure, and steric interactions causes the sheets to form coupled oscillators, whose motion is synchronized in time and space. We develop a heuristic model that rationalizes this behavior. These coupled self-oscillators exhibit rich and tunable phase dynamics, which depends on the sheets’ initial placement, coverage by catalyst and relative size. Moreover, through variations in the reactant concentration, the system can switch between the different oscillatory modes. This breadth of dynamic behavior expands the functionality of the coupled oscillators, enabling soft robots to display a variety of self-sustained, self-regulating moves.
APA, Harvard, Vancouver, ISO, and other styles
32

Gao, Guanghai, Xiao Cong, Yunjing Cui, and Xingqi Qiu. "Study on Vortex-Induced Vibration of Deep-Water Marine Drilling Risers in Linearly Sheared Flows in consideration of Changing Added Mass." Mathematical Problems in Engineering 2020 (February 13, 2020): 1–16. http://dx.doi.org/10.1155/2020/7687280.

Full text
Abstract:
In order to more accurately predict the coupled in-line and cross-flow vortex-induced vibration (VIV) response of deep-water marine drilling risers in linearly sheared flows, an improved three-dimensional time-domain coupled model based on van der Pol wake oscillator models was established in this paper. The impact of the in-line and cross-flow changing added mass coefficients was taken into account in the model. The finite element, Newmark-β, and Newton–Raphson methods were adopted to solve the coupled nonlinear partial differential equations. The entire numerical solution process was realized by a self-developed program based on MATLAB. Comparisons between the numerical calculations and the published experimental tests showed that the improved model can more accurately predict some main features of the coupled in-line and cross-flow VIV of long slender flexible risers in linearly sheared flows to some extent. The coupled in-line and cross-flow VIV of a real-size marine drilling riser, usually used in the deep-water oil/gas industry in the South China Sea, was analyzed. The influence of top tension force and seawater flow speed, as well as platform heave amplitude and frequency, on the riser in-line and cross-flow VIV was also discussed. The results show that the platform heave motion increases the VIV displacements and changes the magnitudes of peak frequencies as well as the components of frequencies. The platform heave motion also has a significant influence on the vibration modes of the middle and upper sections of the riser. The impact level of each factor on the in-line and cross-flow VIV response of the riser is different. The improved model and the results of this paper can be used as a reference for the engineering design of deep-water marine drilling risers.
APA, Harvard, Vancouver, ISO, and other styles
33

HUANG, WEIWEI, CHEE-MENG CHEW, YU ZHENG, and GEOK-SOON HONG. "BIO-INSPIRED LOCOMOTION CONTROL WITH COORDINATION BETWEEN NEURAL OSCILLATORS." International Journal of Humanoid Robotics 06, no. 04 (2009): 585–608. http://dx.doi.org/10.1142/s0219843609001929.

Full text
Abstract:
Central Pattern Generator (CPG) is used in bipedal locomotion control to provide the basic rhythm signal for actuators. Generally, the CPG is composed of many neural oscillators coupled together. In this paper, the coordination between neural oscillators in CPG is studied to achieve robust rhythm motions. By using the entrainment property of the neural oscillator, we develop a method which uses the difference between oscillator's output and desired output to adjust the inner states of neural oscillators. In the simulation, a CPG structure with coordination between neural oscillators is used to control a 2D bipedal robot. The robot can walk continuously when several external forces are applied on the robot during walking. The method is also implemented on our humanoid robot NUSBIP-III ASLAN for the test of walking forward. With the coordination between neural oscillators, the CPG generated rhythmic and robust control signals which enable the robot to walk forward stably.
APA, Harvard, Vancouver, ISO, and other styles
34

Xiao, Heng, and Carlos R. Mechoso. "Correlative Evolutions of ENSO and the Seasonal Cycle in the Tropical Pacific Ocean." Journal of the Atmospheric Sciences 66, no. 4 (2009): 1041–49. http://dx.doi.org/10.1175/2008jas2573.1.

Full text
Abstract:
Abstract This study examines whether shifts between the correlative evolutions of ENSO and the seasonal cycle in the tropical Pacific Ocean can produce effects that are large enough to alter the evolution of the coupled atmosphere–ocean system. The approach is based on experiments with an ocean general circulation model (OGCM) of the Pacific basin, in which the seasonal and nonseasonal (interannually varying) components of the surface forcing are prescribed with different shifts in time. The shift would make no difference in terms of ENSO variability if the system were linear. The surface fluxes of heat and momentum used to force the ocean are taken from 1) simulations in which the OGCM coupled to an atmospheric GCM produces realistic ENSO variability and 2) NCEP reanalysis data corrected by Comprehensive Ocean–Atmosphere Data Set climatology for the 20-yr period 1980–99. It is found that the response to the shifts in terms of eastern basin heat content can be 20%–40% of the maximum interannual anomaly in the first experiment, whereas it is 10%–20% in the second experiment. In addition, the response to the shift is event dependent. A response of this magnitude can potentially generate coupled atmosphere–ocean interactions that alter subsequent event evolution. Analysis of a selected event shows that the major contribution to the response is provided by the anomalous zonal advection of seasonal mean temperature in the equatorial band. Additional OGCM experiments suggest that both directly forced and delayed signals provide comparable contributions to the response. An interpretation of the results based on the “delayed oscillator” paradigm and on equatorial wave–mean flow interaction is given. It is argued that the same oceanic ENSO anomalies in different times of the oceanic seasonal cycle can result in different ENSO evolutions because of nonlinear interactions between equatorially trapped waves at work during ENSO and the seasonally varying upper-ocean currents and thermocline structure.
APA, Harvard, Vancouver, ISO, and other styles
35

Armin, Milad, Sandy Day, Madjid Karimirad, and Mahdi Khorasanchi. "On the development of a nonlinear time-domain numerical method for describing vortex-induced vibration and wake interference of two cylinders using experimental results." Nonlinear Dynamics 104, no. 4 (2021): 3517–31. http://dx.doi.org/10.1007/s11071-021-06527-8.

Full text
Abstract:
AbstractA nonlinear mathematical model is developed in the time domain to simulate the behaviour of two identical flexibly mounted cylinders in tandem while undergoing vortex-induced vibration (VIV). Subsequently, the model is validated and modified against experimental results. Placing an array of bluff bodies in proximity frequently happens in different engineering fields. Chimney stacks, power transmission lines and oil production risers are few engineering structures that may be impacted by VIV. The coinciding of the vibration frequency with the structure natural frequency could have destructive consequences. The main objective of this study is to provide a symplectic and reliable model capable of capturing the wake interference phenomenon. This study shows the influence of the leading cylinder on the trailing body and attempts to capture the change in added mass and damping coefficients due to the upstream wake. The model is using two coupled equations to simulate the structural response and hydrodynamic force in each of cross-flow and stream-wise directions. Thus, four equations describe the fluid–structure interaction of each cylinder. A Duffing equation describes the structural motion, and the van der Pol wake oscillator defines the hydrodynamic force. The system of equations is solved analytically. Two modification terms are added to the excitation side of the Duffing equation to adjust the hydrodynamic force and incorporate the effect of upstream wake on the trailing cylinder. Both terms are functions of upstream shedding frequency (Strouhal number). Additionally, the added mass modification coefficient is a function of structural acceleration and the damping modification coefficient is a function of velocity. The modification coefficients values are determined by curve fitting to the difference between upstream and downstream wake forces, obtained from experiments. The damping modification coefficient is determined by optimizing the model against the same set of experiments. Values of the coefficients at seven different spacings are used to define a universal function of spacing for each modification coefficient so that they can be obtained for any given distance between two cylinders. The model is capable of capturing lock-in range and maximum amplitude.
APA, Harvard, Vancouver, ISO, and other styles
36

QUINN, D. DANE, and FANG WANG. "SYNCHRONIZATION OF COUPLED OSCILLATORS THROUGH CONTROLLED ENERGY TRANSFER." International Journal of Bifurcation and Chaos 10, no. 06 (2000): 1521–35. http://dx.doi.org/10.1142/s0218127400000918.

Full text
Abstract:
We study the phenomena of synchronization in a system of two coupled oscillators. The oscillators, identical when decoupled, model forced pendula and are coupled with a linear torsional spring. Using the idea of energy transfer between the two oscillators, we derive nonlinear control laws which stabilize the in-phase motion. Physically, the additional control terms act through a controlled transfer the energy between the two oscillators. Thus the mechanical energy of the system remains constant as the oscillators are synchronized. Trajectories of the controlled system are required to remain on the constant energy surface of the Hamiltonian of the uncontrolled system, which represents the mechanical energy of the coupled oscillator system.
APA, Harvard, Vancouver, ISO, and other styles
37

Rauk, A., J. L. McCann, H. Wieser, P. Bour, Yu I. El'natanov, and R. G. Kostyanovsky. "Skeletal vibrational circular dichroism of a series of bicyclic dilactones: the fingerprint region?" Canadian Journal of Chemistry 76, no. 6 (1998): 717–25. http://dx.doi.org/10.1139/v98-015.

Full text
Abstract:
The vibrational circular dichroism (VCD) spectra of 2,5-dioxabicyclo[2.2.1]heptane-3,6-dione 1 (R = H) and the 1,4-dialkyl derivatives, 1 (R = Me) and 1 (R = t-Bu), were calculated by the ab initio magnetic field perturbation (MFP) procedure with a B3LYP/6-31G* force field, and the VCD spectra of the dimethyl and di-t-butyl derivatives were measured in the region 800-1500 cm-1. While the absolute configurations of 1 (R = Me) and 1 (R = t-Bu) could be assigned unambiguously by comparison of the experimental and predicted spectra, there is little obvious correspondence between the spectra of the series of compounds. The VCD spectra are analysed on the basis of operation of a coupled oscillator mechanism involving motions of the polar bonds. In the case of the parent dihydro system, bridgehead C-H bond motions appear to dominate contributions to the VCD of vibrational transitions into which they are mixed.Key words: vibrational circular dichroism (VCD), 2,5-dioxabicyclo[2.2.1]heptane-3,6-dione, dilactones, optical activity.
APA, Harvard, Vancouver, ISO, and other styles
38

Yoshida, Shinya, Hiroshi Miyaguchi, and Tsutomu Nakamura. "Prototyping of an All-pMOS-Based Cross-Coupled Voltage Multiplier in Single-Well CMOS Technology for Energy Harvesting Utilizing a Gastric Acid Battery." Electronics 8, no. 7 (2019): 804. http://dx.doi.org/10.3390/electronics8070804.

Full text
Abstract:
A gastric acid battery and its charge storage in a capacitor are a simple and safe method to provide a power source to an ingestible device. For that method, the electromotive force of the battery should be boosted for storing a large amount of energy. In this study, we have proposed an all-p-channel metal-oxide semiconductor (pMOS)-based cross-coupled voltage multiplier (CCVM) utilizing single-well CMOS technology to achieve a voltage boosting higher than from a conventional complementary MOS (CMOS) CCVM. We prototyped a custom integrated circuit (IC) implemented with the above CCVMs and a ring oscillator as a clock source. The characterization experiment demonstrated that our proposed pMOS-based CCVM can boost the input voltage higher because it avoids the body effect problem resulting from an n-channel MOS transistor. This circuit was also demonstrated to significantly reduce the circuit area on the IC, which is advantageous as it reduces the chip size or provides an area for other functional circuits. This simple circuit structure based on mature and low-cost technologies matches well with disposal applications such as an ingestible device. We believe that this pMOS-based CCVM has the potential to become a useful energy harvesting circuit for ingestible devices.
APA, Harvard, Vancouver, ISO, and other styles
39

Zhogoleva, Nadiia, and Volodymyr Shcherbak. "Damping parameters indentification of Lienard polynomial system." Proceedings of the Institute of Applied Mathematics and Mechanics NAS of Ukraine 34 (April 24, 2021): 28–35. http://dx.doi.org/10.37069/1683-4720-2020-34-4.

Full text
Abstract:
In many applications of physics, biology, and other sciences, an approach based on the concept of model equations is used as an approximate model of complex nonlinear processes. The basis of this concept is the provision that a small number of characteristic types movements of simple mathematical models inherent in systems give the key to understanding and exploring a huge number of different phenomena. In particular, it is well known that the complex oscillatory motion can be modeled by a system consisting of one or more coupled nonlinear oscillators that governs by differential equation of a second-order. A Lienard system, namely $ \ddot x(t)+f(x(t))\dot x(t)+g(x(t)) = 0$, is a generalization of the such models. Here $f(x(t))$ and $g(x(t))$ are functions that represent various nonlinear phenomena. The typical sources of nonlinearities in Lienard systems are as follows: large displacements of the structure provoking geometric nonlinearities, a nonlinear material behavior, complex law of damping dissipation, etc. In fact, parameter identification is the base of several engineering tasks: identification can be used for the following: (i) to gain knowledge about the process behavior, (ii) to validate theoretical models, (iii) to tune controller parameters, (iv) to design adaptive control algorithms, (v) to process supervision and fault detection, (vi) to on-line optimization. Hence, in order to represent these nonlinearities, identifying the parameters characterizing their behaviors is essential. The problem of constructing globally convergent identificator for polynomial representation of damping force in general Lienar oscillator is addressed. The method of invariant relations is used for identification scheme design. This aproach is based on dynamical extension of original system and construct of appropriate invariant relations, from which the unknowns parameters can be expressed as a functions of the known quantities on the trajectories of extended system. The final synthesis is carried out from the condition of obtaining asymptotic estimates of unknown parameters. It is shown that an asymptotic estimate of the unknown states can be obtained by rendering attractive an appropriately selected invariant manifold in the extended state space.
APA, Harvard, Vancouver, ISO, and other styles
40

Schwarzenbach, Dieter, Henrik Birkedal, Marc Hostettler, and Peter Fischer. "Neutron diffraction investigation of the temperature dependence of crystal structure and thermal motions of red HgI2." Acta Crystallographica Section B Structural Science 63, no. 6 (2007): 828–35. http://dx.doi.org/10.1107/s0108768107043327.

Full text
Abstract:
The structure of, and anisotropic thermal motions in, the red semiconductor tetrahedral layer structure of HgI2 have been studied with neutron powder diffraction as a function of temperature from 10 to 293 K. Average thermal displacement parameters U eq of the two atoms are comparable in size at 10 K, but U eq(Hg) increases considerably faster with temperature than U eq(I), the Hg—I bond being highly non-rigid. The anisotropic displacement tensor U (I) is strongly anisotropic with one term about twice as large as the others, while U (Hg) is nearly isotropic. All displacement tensor elements, except U 22(I), increase faster with temperature than harmonic quantum oscillator curves indicating a softening of the isolated-atom potentials at large amplitudes. A lattice dynamical model provides arguments that the anisotropic thermal motions of I are dominated by a soft mode with a wavevector at the [½ ½ 0] boundary of the Brillouin zone consisting essentially of coupled librations of the HgI4 tetrahedra, and by translations of the entire layer. The large vibration amplitudes of Hg suggest weak Hg–I force constants compared with the I–I force constants, allowing Hg to move quite freely inside the tetrahedra. The libration mode induces dynamic deformations of the Hg—I bond with twice its frequency. This provides a mechanism for the anharmonicity and may explain the lightening of the color from red to orange upon cooling at ca 80 K.
APA, Harvard, Vancouver, ISO, and other styles
41

Jiao, Guyue. "Design of a Magnetic Interaction-Based Vibration Absorber for Continuous Beam." Shock and Vibration 2020 (June 22, 2020): 1–18. http://dx.doi.org/10.1155/2020/6384308.

Full text
Abstract:
Classical absorber for vibration suppression of a continuous structure is constructed as a spring-mass oscillator, which only provides coupling force to suppress the vibration of primary structure. In this study, absorber beam is introduced and coupled on the continuous primary beam with magnetic interaction. Thus, the magnetic interaction and coupling bending moment affect the responses of primary beam. Based on the model of the system and Galerkin truncation, the natural frequencies for different magnetic parameters are obtained, which demonstrates that the fundamental frequency can be reduced to zero and the vibration of primary beam can be suppressed in a wide frequency band. Considering the vibration suppression on frequency band, we propose two criteria to evaluate the vibration suppression effect: one is the width of band for vibration suppression and the other is the width for vibration absorption. The two criteria not only show the vibration reduction effect but also correspond to different vibration suppression mechanism. Due to the advantages of zero fundamental frequency induced by the proposed magnetic interaction coupling and wide vibration suppression frequency band, utilizing absorber beam in vibration suppression of continuous structure has potential applications for flexible aim in the fields of manufacturing and aerospace.
APA, Harvard, Vancouver, ISO, and other styles
42

Tass, Peter A. "Estimation of the transmission time of stimulus-locked responses: modelling and stochastic phase resetting analysis." Philosophical Transactions of the Royal Society B: Biological Sciences 360, no. 1457 (2005): 995–99. http://dx.doi.org/10.1098/rstb.2005.1635.

Full text
Abstract:
A model of two coupled phase oscillators is studied, where both oscillators are subject to random forces but only one oscillator is repetitively stimulated with a pulsatile stimulus. A pulse causes a reset, which is transmitted to the other oscillator via the coupling. The transmission time of the cross-trial (CT) averaged responses, i.e. the difference in time between the maxima of the CT averaged responses of both oscillators differs from the time difference between the maxima of the oscillators' resets. In fact, the transmission time of the CT averaged responses directly corresponds to the phase difference in the stable synchronized state with integer multiples of the oscillators' mean period added to it. With CT averaged responses it is impossible to reliably estimate the time elapsing, owing to the stimulus' action being transmitted between the two oscillators.
APA, Harvard, Vancouver, ISO, and other styles
43

Grover, Francis M., Sarah M. Schwab, Paula L. Silva, Tamara Lorenz, and Michael A. Riley. "Flexible organization of grip force control during movement frequency scaling." Journal of Neurophysiology 122, no. 6 (2019): 2304–15. http://dx.doi.org/10.1152/jn.00416.2019.

Full text
Abstract:
The grip force applied to maintain grasp of a handheld object has been typically reported as tightly coupled to the load force exerted by the object as it is actively manipulated, occurring proportionally and consistently in phase with changes in load force. However, continuous grip force-load force coupling breaks down when overall load force levels and oscillation amplitudes are lower (Grover F, Lamb M, Bonnette S, Silva PL, Lorenz T, Riley MA. Exp Brain Res 236: 2531–2544, 2018) or more predictable (Grover FM, Nalepka P, Silva PL, Lorenz T, Riley MA. Exp Brain Res 237: 687–703, 2019). Under these circumstances, grip force is instead only intermittently coupled to load force; continuous coupling is prompted only when load force levels or variations become sufficiently high or unpredictable. The current study investigated the nature of the transition between continuous and intermittent modes of grip force control by scaling the load force level and the oscillation amplitude continuously in time by means of scaling the required frequency of movement oscillations. Participants grasped a cylindrical object between the thumb and forefinger and oscillated their arm about the shoulder in the sagittal plane. Oscillation frequencies were paced with a metronome that scaled through an ascending or descending frequency progression. Due to greater accelerations, faster frequencies produced greater overall load force levels and more pronounced load oscillations. We observed smooth but nonlinear transitions between clear regimes of intermittent and continuous grip force-load force coordination, for both scaling directions, indicating that grip force control can flexibly reorganize as parameters affecting grasp (e.g., variations in load force) change over time. NEW & NOTEWORTHY Grip force (GF) is synchronously coupled to changing load forces (LF) during object manipulation when LF levels are high or unpredictable, but only intermittently coupled to LF during less challenging grasp conditions. This study characterized the nature of transitions between synchronous and intermittent GF-LF coupling, revealing a smooth but nonlinear change in intermittent GF modulation in response to continuous scaling of LF amplitude. Intermittent, “drift-and-act” control may provide an alternative framework for understanding GF-LF coupling.
APA, Harvard, Vancouver, ISO, and other styles
44

de la Cruz, H., J. C. Jimenez, and R. J. Biscay. "On the oscillatory behavior of coupled stochastic harmonic oscillators driven by random forces." Statistics & Probability Letters 146 (March 2019): 85–89. http://dx.doi.org/10.1016/j.spl.2018.11.001.

Full text
APA, Harvard, Vancouver, ISO, and other styles
45

Dao, Nguyen Van. "Connected oscillations in a nonlinearly coupled system." Vietnam Journal of Mechanics 25, no. 3 (2003): 129–36. http://dx.doi.org/10.15625/0866-7136/25/3/6585.

Full text
Abstract:
A single-mass plane system subjected to symmetric restoring forces can strongly oscillate in the direction which is free from the external excitation. The raising oscillation is called the connected one. This phenomenon exists only in nonlinear systems under certain resonance conditions and was first investigated by Kononenko V. 0.
APA, Harvard, Vancouver, ISO, and other styles
46

Chan, Whei-Ching C., and Yi-Duo Chao. "Synchronization of Coupled Forced Oscillators." Journal of Mathematical Analysis and Applications 218, no. 1 (1998): 97–116. http://dx.doi.org/10.1006/jmaa.1997.5749.

Full text
APA, Harvard, Vancouver, ISO, and other styles
47

Jia, Jinda, Xiaobiao Shan, Deepesh Upadrashta, Tao Xie, Yaowen Yang, and Rujun Song. "Modeling and Analysis of Upright Piezoelectric Energy Harvester under Aerodynamic Vortex-induced Vibration." Micromachines 9, no. 12 (2018): 667. http://dx.doi.org/10.3390/mi9120667.

Full text
Abstract:
This paper presents an upright piezoelectric energy harvester (UPEH) with cylinder extension along its longitudinal direction. The UPEH can generate energy from low-speed wind by bending deformation produced by vortex-induced vibrations (VIVs). The UPEH has the advantages of less working space and ease of setting up an array over conventional vortex-induced vibration harvesters. The nonlinear distributed modeling method is established based on Euler–Bernoulli beam theory and aerodynamic vortex-induced force of the cylinder is obtained by the van der Pol wake oscillator theory. The fluid–solid–electricity governing coupled equations are derived using Lagrange’s equation and solved through Galerkin discretization. The effect of cylinder gravity on the dynamic characteristics of the UPEH is also considered using the energy method. The influences of substrate dimension, piezoelectric dimension, the mass of cylinder extension, and electrical load resistance on the output performance of harvester are studied using the theoretical model. Experiments were carried out and the results were in good agreement with the numerical results. The results showed that a UPEH configuration achieves the maximum power of 635.04 μW at optimum resistance of 250 kΩ when tested at a wind speed of 4.20 m/s. The theoretical results show that the UPEH can get better energy harvesting output performance with a lighter tip mass of cylinder, and thicker and shorter substrate in its synchronization working region. This work will provide the theoretical guidance for studying the array of multiple upright energy harvesters.
APA, Harvard, Vancouver, ISO, and other styles
48

Holzmann, Daniela, Matthias Sonnleitner, and Helmut Ritsch. "A Versatile Quantum Simulator for Coupled Oscillators Using a 1D Chain of Atoms Trapped near an Optical Nanofiber." Photonics 8, no. 6 (2021): 228. http://dx.doi.org/10.3390/photonics8060228.

Full text
Abstract:
The transversely confined propagating light modes of a nanophotonic optical waveguide or nanofiber can effectively mediate infinite-range forces. We show that for a linear chain of particles trapped within the waveguide’s evanescent field, transverse illumination with a suitable set of laser frequencies should allow the implementation of a coupled-oscillator quantum simulator with time-dependent and widely controllable all-to-all interactions. Using the example of the energy spectrum of oscillators with simulated Coulomb interactions, we show that different effective coupling geometries can be emulated with high precision by proper choice of laser illumination conditions. Similarly, basic quantum gates can be selectively implemented between arbitrarily chosen pairs of oscillators in the energy as well as in the coherent-state basis. Key properties of the system dynamics and states can be monitored continuously by analysis of the out-coupled fiber fields.
APA, Harvard, Vancouver, ISO, and other styles
49

Szűcs, Attila, Robert C. Elson, Michail I. Rabinovich, Henry D. I. Abarbanel, and Allen I. Selverston. "Nonlinear Behavior of Sinusoidally Forced Pyloric Pacemaker Neurons." Journal of Neurophysiology 85, no. 4 (2001): 1623–38. http://dx.doi.org/10.1152/jn.2001.85.4.1623.

Full text
Abstract:
Periodic current forcing was used to investigate the intrinsic dynamics of a small group of electrically coupled neurons in the pyloric central pattern generator (CPG) of the lobster. This group contains three neurons, namely the two pyloric dilator (PD) motoneurons and the anterior burster (AB) interneuron. Intracellular current injection, using sinusoidal waveforms of varying amplitude and frequency, was applied in three configurations of the pacemaker neurons: 1) the complete pacemaker group, 2) the two PDs without the AB, and 3) the AB neuron isolated from the PDs. Depending on the frequency and amplitude of the injected current, the intact pacemaker group exhibited a wide variety of nonlinear behaviors, including synchronization to the forcing, quasiperiodicity, and complex dynamics. In contrast, a single, broad 1:1 entrainment zone characterized the response of the PD neurons when isolated from the main pacemaker neuron AB. The isolated AB responded to periodic forcing in a manner similar to the complete pacemaker group, but with wider zones of synchronization. We have built an analog electronic circuit as an implementation of a modified Hindmarsh-Rose model for simulating the membrane potential activity of pyloric neurons. We subjected this electronic model neuron to the same periodic forcing as used in the biological experiments. This four-dimensional electronic model neuron reproduced the autonomous oscillatory firing patterns of biological pyloric pacemaker neurons, and it expressed the same stationary nonlinear responses to periodic forcing as its biological counterparts. This adds to our confidence in the model. These results strongly support the idea that the intact pyloric pacemaker group acts as a uniform low-dimensional deterministic nonlinear oscillator, and the regular pyloric oscillation is the outcome of cooperative behavior of strongly coupled neurons, having different dynamical and biophysical properties when isolated.
APA, Harvard, Vancouver, ISO, and other styles
50

Widiasari, Fransiska R., Alexander A. Iskandar, and May-On Tjia. "Validity of classical coupled oscillators model for elucidating surface plasmon effects on optical scattering by silver nanocylinders." Journal of Nonlinear Optical Physics & Materials 25, no. 01 (2016): 1650006. http://dx.doi.org/10.1142/s0218863516500065.

Full text
Abstract:
A study is conducted to examine the possibility of explaining the spectral features TE wave scattered by a single and two silver nanocylinders on the basis of a classical coupled oscillators model. The two oscillators representing the nanocylinder are specified by separate eigen frequencies and damping factors with a coupling constant between them, while the influences of the incoming wave on the oscillators are represented by separate driving forces. The validity of the model is examined by the quality of fitting and its resulted spectral profiles with those calculated from the exact formulation of Mie theory. In the case of a single nanocylinder, excellent fit of [Formula: see text] is found for cylinder radius ranging from 20[Formula: see text]nm to 40[Formula: see text]nm. The best fitted parameters show that the so-called dark oscillator has a narrow spectral profile representing the contribution of surface plasmon resonance while the other so-called bright oscillator has a broad spectral profile that can be associated with the contribution of the slowly-varying scattered background. For scattering by two nanocylinders with separation [Formula: see text], excellent fits are also obtained for wide range of [Formula: see text] from 15[Formula: see text]nm to 100[Formula: see text]nm by introducing Lorentzian-like dispersive coupling between the dark oscillators for both incident light normal and along the axis connecting the cylinders. This study has thus demonstrated the roles of surface plasmon and the plasmonic interactions for the appearance of Fano-like asymmetric cross-section profile.
APA, Harvard, Vancouver, ISO, and other styles
We offer discounts on all premium plans for authors whose works are included in thematic literature selections. Contact us to get a unique promo code!