Готові списки джерел за темами / Natural oscillatory system

Добірка наукової літератури з теми "Natural oscillatory system"

Автор: Grafiati

Опубліковано: 30 травня 2022

Оновлено: 31 травня 2022

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Статті в журналах з теми "Natural oscillatory system"

Kurkin, Semen A., Danil D. Kulminskiy, Vladimir I. Ponomarenko, Mikhail D. Prokhorov, Sergey V. Astakhov, and Alexander E. Hramov. "Central pattern generator based on self-sustained oscillator coupled to a chain of oscillatory circuits." Chaos: An Interdisciplinary Journal of Nonlinear Science 32, no. 3 (March 2022): 033117. http://dx.doi.org/10.1063/5.0077789.

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We have proposed and studied both numerically and experimentally a multistable system based on a self-sustained Van der Pol oscillator coupled to passive oscillatory circuits. The number of passive oscillators determines the number of multistable oscillatory regimes coexisting in the proposed system. It is shown that our system can be used in robotics applications as a simple model for a central pattern generator (CPG). In this case, the amplitude and phase relations between the active and passive oscillators control a gait, which can be adjusted by changing the system control parameters. Variation of the active oscillator’s natural frequency leads to hard switching between the regimes characterized by different phase shifts between the oscillators. In contrast, the external forcing can change the frequency and amplitudes of oscillations, preserving the phase shifts. Therefore, the frequency of the external signal can serve as a control parameter of the model regime and realize a feedback in the proposed CPG depending on the environmental conditions. In particular, it allows one to switch the regime and change the velocity of the robot’s gate and tune the gait to the environment. We have also shown that the studied oscillatory regimes in the proposed system are robust and not affected by external noise or fluctuations of the system parameters. Moreover, using the proposed scheme, we simulated the type of bipedal locomotion, including walking and running.

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Zaitsev, Valery V., and Alexander V. Karlov. "Quasi-harmonic self-oscillations in discrete time: analysis and synthesis of dynamic systems." Physics of Wave Processes and Radio Systems 24, no. 4 (January 16, 2022): 19–24. http://dx.doi.org/10.18469/1810-3189.2021.24.4.19-24.

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For sampling of time in a differential equation of movement of Thomson type oscillator (generator) it is offered to use a combination of the numerical method of finite differences and an asymptotic method of the slowl-changing amplitudes. The difference approximations of temporal derivatives are selected so that, first, to save conservatism and natural frequency of the linear circuit of self-oscillatory system in the discrete time. Secondly, coincidence of the difference shortened equation for the complex amplitude of self-oscillations in the discrete time with Eulers approximation of the shortened equation for amplitude of self-oscillations in analog system prototype is required. It is shown that realization of such approach allows to create discrete mapping of the van der Pol oscillator and a number of mappings of Thomson type oscillators. The adequacy of discrete models to analog prototypes is confirmed with also numerical experiment.

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GEORGIOU, IOANNIS T., and IRA B. SCHWARTZ. "THE SLOW INVARIANT MANIFOLD OF A CONSERVATIVE PENDULUM-OSCILLATOR SYSTEM." International Journal of Bifurcation and Chaos 06, no. 04 (April 1996): 673–92. http://dx.doi.org/10.1142/s0218127496000345.

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We analyze the motions of a conservative pendulum-oscillator system in the context of invariant manifolds of motion. Using the singular perturbation methodology, we show that whenever the natural frequency of the oscillator is sufficiently larger than that of the pendulum, there exists a global invariant manifold passing through all static equilibrium states and tangent to the linear eigenspaces at these equilibrium states. The invariant manifold, called slow, carries a continuum of slow periodic motions, both oscillatory and rotational. Computations to various orders of approximation to the slow invariant manifold allow analysis of motions on the slow manifold, which are verified with numerical experiments. Motion on the slow invariant manifold is identified with a slow nonlinear normal mode.

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Krak, Michael D., and Rajendra Singh. "Asymptotic trends in time-varying oscillatory period for a dual-staged torsional system." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 231, no. 22 (July 28, 2016): 4126–38. http://dx.doi.org/10.1177/0954406216662087.

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The primary goal of this article is to propose a new analysis tool that estimates the asymptotic trends in the time-varying oscillatory period of a non-linear mechanical system. The scope is limited to the step-response of a torsional oscillator containing a dry friction element and dual-staged spring. Prior work on the stochastic linearization techniques is extended and modified for application in time domain. Subsequently, an instantaneous expected value operator and the concept of instantaneous effective stiffness are proposed. The non-linear system is approximated at some instant during the step-response by a linear time-invariant mechanical system that utilizes the instantaneous effective stiffness concept. The oscillatory period of the non-linear step-response at that instant is then approximated by the natural period of the corresponding linear system. The proposed method is rigorously illustrated via two computational example cases (a near backlash and near pre-load non-linearities), and the necessary digital signal processing parameters for time domain analysis are investigated. Finally, the feasibility and applicability of the proposed method is demonstrated by estimating the softening and hardening trends in the time-varying oscillatory period of the measured response for two laboratory experiments that contain clearance elements and multi-staged torsional springs.

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Matevosyan, Ashot A., and Aram G. Matevosyan. "PARAMETER ESTIMATION FOR OSCILLATORY SYSTEMS." Proceedings of the YSU A: Physical and Mathematical Sciences 55, no. 2 (255) (August 30, 2021): 131–40. http://dx.doi.org/10.46991/pysu:a/2021.55.2.131.

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Simple harmonic motion was investigated of a rotational oscillating system. The effect of dumping and forcing on motion of the system was examined and measurements were taken. Resonance in a oscillating system was investigated and quality factor of the dumping system was measured at different damping forces using three different methods. Resonance curves were constructed at two different damping forces. A probabilistic model was built and system parameters were estimated from the resonance curves using Stan sampling platform. The quality factor of the oscillating system when the additional dumping was turned off was estimated to be $Q = \num{71 \pm 1}$ and natural frequency $\omega_0 = \num{3.105 \pm 0.008}\, \si{\per\second}$.

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Yelisieiev, Volodymyr, Vasyl Lutsenko, Serhii Shevchenko, Anatolii Shevchenko, Oleksandr Tolstopyat, and Leonid Fleer. "Response of oscillatory system “liquid layer-rod” to driving disturbances." E3S Web of Conferences 109 (2019): 00118. http://dx.doi.org/10.1051/e3sconf/201910900118.

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This article deals with main characteristics of the oscillating system “central body – liquid” by means of its well-known representation in the form of a pendulum mathematical model. It makes possible to evaluate spread of specified disturbances at the general physical level and to determine the most dangerous frequencies that lead to increased amplitudes of fluid oscillations. We propose equations for single-frequency pendulums, which influence each other by means of resistance forces and added mass. Several examples with different natural frequencies of the body are considered. The calculation results showed that besides natural frequencies of the components, system has two more natural frequencies. So, system actually responds only to disturbances which frequencies are close to the natural frequency of the liquid layer. In this case, amplitudes of liquid and the body sharply increase. This fact indicates that in real technological processes frequency of dominant disturbance should be as far from the first resonant frequency of the liquid as possible. The further experimental and theoretical studies that take into account the influence of the following modes on the dynamic picture of the process are also of interest.

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Agrawal, Deepak K., Elisa Franco, and Rebecca Schulman. "A self-regulating biomolecular comparator for processing oscillatory signals." Journal of The Royal Society Interface 12, no. 111 (October 2015): 20150586. http://dx.doi.org/10.1098/rsif.2015.0586.

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While many cellular processes are driven by biomolecular oscillators, precise control of a downstream on/off process by a biochemical oscillator signal can be difficult: over an oscillator's period, its output signal varies continuously between its amplitude limits and spends a significant fraction of the time at intermediate values between these limits. Further, the oscillator's output is often noisy, with particularly large variations in the amplitude. In electronic systems, an oscillating signal is generally processed by a downstream device such as a comparator that converts a potentially noisy oscillatory input into a square wave output that is predominantly in one of two well-defined on and off states. The comparator's output then controls downstream processes. We describe a method for constructing a synthetic biochemical device that likewise produces a square-wave-type biomolecular output for a variety of oscillatory inputs. The method relies on a separation of time scales between the slow rate of production of an oscillatory signal molecule and the fast rates of intermolecular binding and conformational changes. We show how to control the characteristics of the output by varying the concentrations of the species and the reaction rates. We then use this control to show how our approach could be applied to process different in vitro and in vivo biomolecular oscillators, including the p53-Mdm2 transcriptional oscillator and two types of in vitro transcriptional oscillators. These results demonstrate how modular biomolecular circuits could, in principle, be combined to build complex dynamical systems. The simplicity of our approach also suggests that natural molecular circuits may process some biomolecular oscillator outputs before they are applied downstream.

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Stein, George Juraj, Peter Tobolka, and Rudolf Chmúrny. "Preliminary Investigations of Machine Frame Vibration Damping Using Eddy Current Principle." Applied Mechanics and Materials 821 (January 2016): 288–94. http://dx.doi.org/10.4028/www.scientific.net/amm.821.288.

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A novel approach to vibration attenuation, based on the eddy current principle, is described. The combined effects of all magnetic forces acting in the oscillatory system attenuate frame vibrations and, concurrently, decrease the damped natural frequency. A mathematical model of the forces balance in the oscillatory system was derived before. Some experimental results from a mock-up machine frame excited by an asynchronous motor are presented.

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Khoroshev, K. G., and S. V. Kykot. "Eigenfrequencies and eigenforms of regular chain oscillatory systems." Bulletin of Taras Shevchenko National University of Kyiv. Series: Physics and Mathematics, no. 4 (2021): 88–93. http://dx.doi.org/10.17721/1812-5409.2021/4.14.

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The classical approach in the investigation of natural oscillations of discrete mechanical oscillatingsystems is the solution of the secular equation for finding the eigenfrequencies and the system of algebraic equations for determining the amplitude coefficients (eigenforms). However, the analytical solution of the secular equation is possible only for a limited class of discrete systems, especially with a finite degree of freedom. This class includes regular chain oscillating systems in which the same oscillators are connected in series. Regular systems are divided into systems with rigidly fixed ends, with one or both free ends, which significantly affects the search for eigenfrequencies and eigenforms. This paper shows how, having a solution for the secular equation of a regular system with rigidly fixed ends, it is possible to determine the eigenfrequencies and eigenforms of regular systems with one or both free ends.

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Gale, Steven, Mario Prsa, Aaron Schurger, Annietta Gay, Aurore Paillard, Bruno Herbelin, Jean-Philippe Guyot, Christophe Lopez, and Olaf Blanke. "Oscillatory neural responses evoked by natural vestibular stimuli in humans." Journal of Neurophysiology 115, no. 3 (March 1, 2016): 1228–42. http://dx.doi.org/10.1152/jn.00153.2015.

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While there have been numerous studies of the vestibular system in mammals, less is known about the brain mechanisms of vestibular processing in humans. In particular, of the studies that have been carried out in humans over the last 30 years, none has investigated how vestibular stimulation (VS) affects cortical oscillations. Here we recorded high-density electroencephalography (EEG) in healthy human subjects and a group of bilateral vestibular loss patients (BVPs) undergoing transient and constant-velocity passive whole body yaw rotations, focusing our analyses on the modulation of cortical oscillations in response to natural VS. The present approach overcame significant technical challenges associated with combining natural VS with human electrophysiology and reveals that both transient and constant-velocity VS are associated with a prominent suppression of alpha power (8–13 Hz). Alpha band suppression was localized over bilateral temporo-parietal scalp regions, and these alpha modulations were significantly smaller in BVPs. We propose that suppression of oscillations in the alpha band over temporo-parietal scalp regions reflects cortical vestibular processing, potentially comparable with alpha and mu oscillations in the visual and sensorimotor systems, respectively, opening the door to the investigation of human cortical processing under various experimental conditions during natural VS.

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Дисертації з теми "Natural oscillatory system"

Грицунов, А. В., И. Н. Бондаренко, А. Б. Галат, О. В. Глухов, and А. Г. Пащенко. "On the quantum electrodynamics of nanosystems." Thesis, Kharkiv, bookfabrik, 2019. http://openarchive.nure.ua/handle/document/10408.

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Problems of quantum dynamics of nanoobjects essential for development of new nanoelectronic systems are discussed. According to the theory of natural oscillatory systems (NOSs), “interaction” between the objects is interpreted as a quantum-dynamic phenomenon meaning a stable trend arising from the quantum chaos. As an opposite, “interchange” is denominated as the permanent stochastic exchange with action quanta between different NOSs in 4D spacetime, being the physical base of the quantum chaos. The Tetrode-Wheeler-Feynman’s concept of “direct interparticle action” is reconciled with both the quantum radiation-absorption and the Coulomb interaction. A conservation law for the action is supposed as a necessary condition for the momentum-energy conservation. The “classic” conservation law for the momentum-energy is considered as derivative, being valid for the momentum as well as some physical value that is an integral over 3D space from a linear combination of stress-energy tensor principal diagonal terms. Such redefinition enables the unconditional quantization of the energy unlike “orthodox” quantum theory.

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Грицунов, А. В., И. Н. Бондаренко, and И. Ю. Близнюк. "Stochastic wave packets of natural oscillatory systems." Thesis, Харьковский национальный университет радиоэлектроники, 2017. http://openarchive.nure.ua/handle/document/6891.

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De Broglie waves are interpreted as oscillations of generalized coordinates of natural oscillatory systems with distributed parameters (NOSs). The action four-scalar and the momentum- energy four-vector both are assimilated with the geometry of NOS eigenmodes in the Minkowski spacetime. A conservation law for the action is supposed as a necessary condition for the energy-momentum conservation. The Wheeler-Feynman’s concept of “direct interparticle action” is developed for both the quantum radiation-absorption and the Coulomb interaction. The spatio-temporal localization of NOS wave packets and Heisenberg’s “uncertainty principle” both are assumed to be results of stochastic exchange with action quanta between different NOSs. The simplest examples of NOS wave packets are given. Some outcomes of application of this theory to solid state phenomena are discussed.

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Jayakumar, J. S. "Analysis Of Two Phase Natural Circulation System Under Oscillatory Conditions." Thesis, 1999. http://etd.iisc.ernet.in/handle/2005/1519.

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Грицунов, А. В., И. Н. Бондаренко, А. Г. Пащенко, and О. Ю. Бабиченко. "Theory of Natural Oscillatory Systems and Advance in Nanoelectronics." Thesis, 2018. http://openarchive.nure.ua/handle/document/6897.

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Specific treatments of some quantum phenomena substantial for progress in nanotechnology and nanoelectronics are presented. De Broglie waves are interpreted as oscillations of the generalized coordinates of natural oscillatory systems with distributed parameters (NOSs). The spatio-temporal localization of the NOS wave packets and Heisenberg’s uncertainty principle both are assumed to be results of the stochastic exchange with action quanta between different NOSs. The quantum kinematics (spatio-temporal evolution of NOS wave packets), quantum dynamics (interaction by means of random exchange with momentum-energy quanta between wave packets of different NOSs), and quantum statistics (probability laws for the stochastic exchange with action quanta between the wave packets in the Minkowski spacetime) are discussed. Both the action four-scalar and the momentum-energy four-vector, as the directional flow of action through 3D world, are assimilated with the geometry of NOS eigenmodes in the Minkowski spacetime. The conservation law for the action is supposed as a necessary condition for the energy-momentum conservation. The simplest examples of NOS wave packets are given. Some outcomes of application of this theory to solid-state phenomena are discussed.

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Книги з теми "Natural oscillatory system"

Boudreau, Joseph F., and Eric S. Swanson. Nonlinear dynamics and chaos. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198708636.003.0013.

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Simple maps and dynamical systems are used to explore chaos in nature. The discussion starts with a review of the properties of nonlinear ordinary differential equations, including the useful concepts of phase portraits, fixed points, and limit cycles. These notions are developed further in an examination of iterative maps that reveal chaotic behavior. Next, the damped driven oscillator is used to illustrate the Lyapunov exponent that can be used to quantify chaos. The famous KAM theorem on the conditions under which chaotic behavior occurs in physical systems is also presented. The principle is illustrated with the Hénon-Heiles model of a star in a galactic environment and billiard models that describe the motion of balls in closed two-dimensional regions.

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Epstein, Irving R., and John A. Pojman. An Introduction to Nonlinear Chemical Dynamics. Oxford University Press, 1998. http://dx.doi.org/10.1093/oso/9780195096705.001.0001.

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Just a few decades ago, chemical oscillations were thought to be exotic reactions of only theoretical interest. Now known to govern an array of physical and biological processes, including the regulation of the heart, these oscillations are being studied by a diverse group across the sciences. This book is the first introduction to nonlinear chemical dynamics written specifically for chemists. It covers oscillating reactions, chaos, and chemical pattern formation, and includes numerous practical suggestions on reactor design, data analysis, and computer simulations. Assuming only an undergraduate knowledge of chemistry, the book is an ideal starting point for research in the field. The book begins with a brief history of nonlinear chemical dynamics and a review of the basic mathematics and chemistry. The authors then provide an extensive overview of nonlinear dynamics, starting with the flow reactor and moving on to a detailed discussion of chemical oscillators. Throughout the authors emphasize the chemical mechanistic basis for self-organization. The overview is followed by a series of chapters on more advanced topics, including complex oscillations, biological systems, polymers, interactions between fields and waves, and Turing patterns. Underscoring the hands-on nature of the material, the book concludes with a series of classroom-tested demonstrations and experiments appropriate for an undergraduate laboratory.

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Tiwari, Sandip. Semiconductor Physics. Oxford University Press, 2020. http://dx.doi.org/10.1093/oso/9780198759867.001.0001.

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A graduate-level text, Semiconductor physics: Principles, theory and nanoscale covers the central topics of the field, together with advanced topics related to the nanoscale and to quantum confinement, and integrates the understanding of important attributes that go beyond the conventional solid-state and statistical expositions. Topics include the behavior of electrons, phonons and photons; the energy and entropic foundations; bandstructures and their calculation; the behavior at surfaces and interfaces, including those of heterostructures and their heterojunctions; deep and shallow point perturbations; scattering and transport, including mesoscale behavior, using the evolution and dynamics of classical and quantum ensembles from a probabilistic viewpoint; energy transformations; light-matter interactions; the role of causality; the connections between the quantum and the macroscale that lead to linear responses and Onsager relationships; fluctuations and their connections to dissipation, noise and other attributes; stress and strain effects in semiconductors; properties of high permittivity dielectrics; and remote interaction processes. The final chapter discusses the special consequences of the principles to the variety of properties (consequences of selection rules, for example) under quantum-confined conditions and in monolayer semiconductor systems. The text also bring together short appendices discussing transform theorems integral to this study, the nature of random processes, oscillator strength, A and B coefficients and other topics important for understanding semiconductor behavior. The text brings the study of semiconductor physics to the same level as that of the advanced texts of solid state by focusing exclusively on the equilibrium and off-equilibrium behaviors important in semiconductors.

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Mathematics of Continuous and Discrete Dynamical Systems (Contemporary Mathematics). Amer Mathematical Society, 2012.

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Частини книг з теми "Natural oscillatory system"

Garrett, Steven L. "The Simple Harmonic Oscillator." In Understanding Acoustics, 59–131. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-44787-8_2.

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Abstract This chapter will introduce a system that is fundamental to our understanding of more physical phenomena than any other. Although the “simple” harmonic oscillator seems to be only the combination of the most mundane components, the formalism developed to explain the behavior of a mass, spring, and damper is used to describe systems that range in size from atoms to oceans. Our investigation goes beyond the “traditional” treatments found in the elementary physics textbooks. For example, the introduction of damping will open a two-way street: a damping element (i.e., a mechanical resistance, Rm) will dissipate the oscillator’s energy, reducing the amplitudes of successive oscillations, but it will also connect the oscillator to the surrounding environment that will return thermal energy to the oscillator. The excitation of a harmonic oscillator by an externally applied force, displacement, or combination of the two will result in a response that is critically dependent upon the relationship between the frequency of excitation and the natural frequency of the oscillator and will introduce the critical concepts of mechanical impedance, resonance, and quality factor. Finally, the harmonic oscillator model will be extended to coupled oscillators that are represented by combinations of several masses and several springs.

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Landa, P. S. "Natural oscillations of non-linear oscillators." In Nonlinear Oscillations and Waves in Dynamical Systems, 71–84. Dordrecht: Springer Netherlands, 1996. http://dx.doi.org/10.1007/978-94-015-8763-1_8.

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Wang, Tianshi, and Jaijeet Roychowdhury. "PHLOGON: PHase-based LOGic using Oscillatory Nano-systems." In Unconventional Computation and Natural Computation, 353–66. Cham: Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-08123-6_29.

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Landa, P. S. "Natural oscillations in systems of coupled oscillators." In Nonlinear Oscillations and Waves in Dynamical Systems, 85–105. Dordrecht: Springer Netherlands, 1996. http://dx.doi.org/10.1007/978-94-015-8763-1_9.

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Dean, Jeffrey. "Locomotion in Insects: Patterns Generated by Interacting Oscillators." In Prerational Intelligence: Adaptive Behavior and Intelligent Systems Without Symbols and Logic, Volume 1, Volume 2 Prerational Intelligence: Interdisciplinary Perspectives on the Behavior of Natural and Artificial Systems, Volume 3, 391–405. Dordrecht: Springer Netherlands, 2000. http://dx.doi.org/10.1007/978-94-010-0870-9_26.

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Epstein, Irving R., and John A. Pojman. "Biological Oscillators." In An Introduction to Nonlinear Chemical Dynamics. Oxford University Press, 1998. http://dx.doi.org/10.1093/oso/9780195096705.003.0019.

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Including a chapter on biological oscillators was not an easy decision. In one sense, no book on nonlinear chemical dynamics would be complete without such a chapter. Not only are the most important and most numerous examples of chemical oscillators to be found in living systems, but the lure of gaining some insight into the workings of biological oscillators and into the remarkable parallels between chemical and biological oscillators attracts many, perhaps most, new initiates to the study of “exotic” chemical systems. On the other hand, it is impossible for us to do even a minimal job of covering the ground that ought to be covered, either in breadth or in depth. To say that the subject demands a whole book is to understate the case badly. There are indeed whole books, many of them excellent, devoted to various aspects of biological oscillators. We mention here only four of our favorites, the volumes by Winfree (1980), Glass and Mackey (1988), Murray (1993) and Goldbeter (1996). Having abandoned the unreachable goal of surveying the field, even superficially, we have opted to present brief looks at a handful of oscillatory phenomena in biology. Even here, our treatment will only scratch the surface. We suspect that, for the expert, this chapter will be the least satisfying in the book. Nonetheless, we have included it because it may also prove to be the most inspiring chapter for the novice. The range of periods of biological oscillators is considerable, as shown in Table 13.1. In this chapter, we focus on three examples of biological oscillation: the activity of neurons; polymerization of microtubulcs; and certain pathological conditions, known as dynamical diseases, that arise from changes in natural biological rhythms. With the possible exception of the first topic, these are not among the best-known nor the most thoroughly studied biological oscillators; they have been chosen because we feel that they can be presented, in a few pages, at a level that will give the reader a sense of the fascinating range of problems offered by biological systems.

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"Perturbation Methods for Oscillatory Systems." In Mathematical Methods for the Natural and Engineering Sciences, 321–66. World Scientific, 2017. http://dx.doi.org/10.1142/9789813202719_0008.

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"Perturbation Methods for Oscillatory Systems." In Mathematical Methods for the Natural and Engineering Sciences, 357–407. WORLD SCIENTIFIC, 2004. http://dx.doi.org/10.1142/9789812562548_0008.

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Murray, Richard M. "Biological Circuit Components." In Biomolecular Feedback Systems. Princeton University Press, 2014. http://dx.doi.org/10.23943/princeton/9780691161532.003.0005.

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This chapter describes some simple circuit components that have been constructed in E. coli cells using the technology of synthetic biology and then considers a more complicated circuit that already appears in natural systems to implement adaptation. It first analyzes the negatively autoregulated gene fabricated in E. coli bacteria, before turning to the toggle switch, which is composed of two genes that mutually repress each other. The chapter next illustrates a dynamical model of a “repressilator”—an oscillatory genetic circuit consisting of three repressors arranged in a ring fashion. The activator–repressor clock is then considered, alongside an incoherent feedforward loop (IFFL). Finally, the chapter examines bacterial chemotaxis, which E. coli use to move in the direction of increasing nutrients.

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Epstein, Irving R., and John A. Pojman. "Introduction—A Bit of History." In An Introduction to Nonlinear Chemical Dynamics. Oxford University Press, 1998. http://dx.doi.org/10.1093/oso/9780195096705.003.0006.

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Oscillations of chemical origin have been present as long as life itself. Every living system contains scores, perhaps hundreds, of chemical oscillators. The systematic study of oscillating chemical reactions and of the broader field of nonlinear chemical dynamics is of considerably more recent origin, however. In this chapter, we present a brief and extremely idiosyncratic overview of some of the history of nonlinear chemical dynamics. In 1828, Fechner described an electrochemical cell that produced an oscillating current, this being the first published report of oscillations in a chemical system. Ostwald observed in 1899 that the rate of chromium dissolution in acid periodically increased and decreased. Because both systems were inhomogeneous, it was believed then, and through much of our own century, that homogeneous oscillating reactions were impossible. Degn wrote in 1972 (p. 302): “It is hard to think of any other question which already occupied chemists in the nineteenth century and still has not received a satisfactory answer.” In that same year, though, answers were coming. How it took so long for the nature of oscillating chemical reactions to be understood and how that understanding eventually came about will be the major focus of this chapter. Although oscillatory behavior can be seen in many chemical systems, we shall concentrate primarily on homogeneous, isothermal reactions in aqueous solution. In later chapters, we shall broaden our horizons a bit. While the study of oscillating reactions did not become well established until the mid-1970s, theoretical discussions go back to at least 1910. We consider here some of the early theoretical and experimental work that led up to the ideas of Prigogine on nonequilibrium thermodynamics and to the experimental and theoretical work of Belousov, Zhabotinsky, Field, Körös, and Noyes, all of whom did much to persuade chemists that chemical oscillations, traveling fronts, and other phenomena that now comprise the repertoire of nonlinear chemical dynamics were deserving of serious study. Alfred Lotka was one of the more interesting characters in the history of science. He wrote a handful of theoretical papers on chemical oscillation during the early decades of this century and authored a monograph (1925) on theoretical biology that is filled with insights that still seem fresh today.

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Тези доповідей конференцій з теми "Natural oscillatory system"

Kamakura, Katsuyoshi, and Hiroyuki Ozoe. "OSCILLATORY DOUBLE DIFFUSIVE NATURAL CONVECTION IN A TWO-LAYER SYSTEM." In International Heat Transfer Conference 10. Connecticut: Begellhouse, 1994. http://dx.doi.org/10.1615/ihtc10.3590.

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Rivera Ramírez, José Luis, and Luis Omar Becerra Santiago. "Natural Gas Density Measurement with an Oscillator type Density meter." In NCSL International Workshop & Symposium. NCSL International, 2020. http://dx.doi.org/10.51843/wsproceedings.2020.28.

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The density results of a natural gas sample are presented, which were obtained by making the measurement experimentally using an oscillatory type density meter. This instrument is used in applications for research and development of measurement systems, as well as in industries. The measurement system that was designed to determine the density of natural gas was worked with pressure values within the range of 80 to 1 000 kPa and at a constant temperature of 20 ° C. The experimental results of the density of natural gas were compared with results obtained with the calculation according to ISO 9676: 2016 standard, obtaining satisfactory conclusions.

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Avila, Ruben, and Eduardo Ramos. "The Influence of a Harmonic Motion on a Melting Process With Natural Convection." In ASME 2013 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/imece2013-64833.

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We study the heat transfer rate in an oscillatory, two dimensional solid-liquid system which is melted from below. As the phase change process takes place, the height of the fluid layer in the lower part of the cavity is continuously enlarged. The influence of the angular frequency of the motion (Taylor number) and the melting rate (Stefan number) on: (i) the heat transfer in the liquid (Nusselt number), (ii) the temperature field and (iii) the shape of the interface, is analyzed. The governing equations together with the Stefan condition at the interface are solved by using a spectral element method. It is observed that as the height of the liquid layer increases, a non-steady unicellular flow appears, and it leads to an oscillatory behaviour of the Nusselt number. As the height of the liquid layer increases further, the onset of the thermal convection and its instabilities modify the shape of the interface, and the heat transfer rate in the molten material. We find that (i) for large Stefan numbers, the heat is transported mostly along the inclined walls, while for low Stefan numbers, a Rayleigh-Bénard type convection is dominant, and (ii) for large Taylor numbers, the motion induced by the oscillation is small, resulting in a Nusselt number that decreases monotonously as a function of time, in contrast, for small Taylor numbers, an oscillatory Nusselt number is displayed.

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Jeong, Youn-Ju, Young-Jun You, Du-Ho Lee, and Min-Su Park. "Experimental Study on Water Damping Effects of Hybrid Floating Structure." In ASME 2013 32nd International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/omae2013-10161.

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In this study, in order to evaluate water damping effects of hybrid pontoon system with cylinders, experimental studies were carried out. At first, in order to evaluate oscillatory motions, three small-scale models of hybrid, tapered, and pontoon were fabricated and tested under the still-water condition. Four acceleration gauges were attached on the top edges and acceleration of top edge were measured during the oscillation. Then, oscillatory motions of oscillation period and stabilizing time to steady-state were analyzed. Finally, based on the oscillatory motions, damping properties of the logarithmic decrement, damping ratio, and natural frequency of damped system were calculated and compared with each other. As the results of this study, it was found that hybrid model presented about 3.67 times higher decay rate of amplitude of the oscillatory motion than the pontoon model. Also, hybrid model presented about 3.67 times higher damping ratio than the pontoon model. Whereas the natural frequency of the pontoon and tapered model were nearly same with the natural frequency of undamped system, that of the hybrid model presented some difference with the that of the undamped system. In addition, periods of floating body at the wet mode presented about 1.5∼3.0 times longer periods than the dry mode, and it was expected that there was not possibility for the resonance. Therefore, it was expected that the hybrid model of this study should contribute to improve serviceability and safety of offshore floating structures as decreasing oscillatory motions.

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Costa, José Lucas De Melo, Asdrubal N. Queiroz Filho, Ismael H. F. Santos, Rodrigo Augusto Barreira, Anna Helena Reali Costa, Edson Satoshi Gomi, and Eduardo Aoun Tannuri. "FPSO Mooring Line Integrity Supervising System Based on Motion Data and Natural Frequency Estimation." In ASME 2021 40th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/omae2021-62991.

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Abstract Offshore production facilities play a central role in the oil industry given the growing demand for energy resources. The mooring system of these floating structures is a critical component for safety maintenance. The timely identification of mooring lines failures can prevent environmental pollution, property losses and further system failures. In this paper we propose a system to detect and classify failures of the mooring lines based on the natural period in the longitudinal axis and in the lateral axis of the long drift oscillatory motion of the platform. The proposal starts from the hypothesis that when a line break occurs, the natural period of oscillation of the platform is increased, and this difference may indicate the malfunction of the mooring system. The proof of concept developed for the proposed system demonstrates the potential of using the natural period to detect failures in mooring lines for floating vessels, validating the initial hypothesis that the difference in a natural period appears when a line breaks and that this difference may detect line break.

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Mojahedi, Mahdi, Keikhosrow Firoozbakhsh, and Mohammad Taghi Ahmadian. "The Oscillatory Behavior of Doubly Clamped Microgyroscopes Under Electrostatic Actuation and Detection." In ASME 2013 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/detc2013-12202.

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In MEMS gyroscopes, it is essential to use matched resonance frequencies of the drive and sense vibrational modes for improving the sensitivity. For this end, the natural frequencies can be tuned by voltages. In this study, a new model is utilized to determine the natural frequencies of the doubly clamped beam microgyroscope. In the model, nonlinear electrostatic forces, fringing fields and mid-plane stretching of the beam are considered. The system is actuated and sensed by electrostatic force and its natural frequencies and stiffness are detuned by DC voltages. The oscillatory problem of the gyroscope is analytically solved versus DC voltages for different design parameters.

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Caruntu, Dumitru I., and Le Luo. "Reduced Order Model of CNT Cantilever Resonators Under AC Voltage Near Half Natural Frequency." In ASME 2013 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/imece2013-64075.

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This paper deals with electrostatically actuated Carbon Nano-Tubes (CNT) cantilevers using Reduced Order Model method. The system consists of a CNT parallel to a ground plate. An alternating current (AC) voltage is considered between the two. The CNT undergoes an oscillatory motion due to the electrostatic force generated by the voltage. Another two forces act on the CNT, namely a damping force, and a van der Waals force due to gaps less than 50 nm. The Method of Multiple Scales (MMS) and the Reduced Order Model (ROM) method (using AUTO solver) are used to investigate the system under soft excitations and/or weak nonlinearities. The frequency response is found in the case of AC near half natural frequency.

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Liao, Yixiang, Christoph Schuster, Suqing Hu, and Dirk Lucas. "CFD Modelling of Flashing Instability in Natural Circulation Cooling Systems." In 2018 26th International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/icone26-81787.

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Passive cooling systems driven by natural circulation are common design features of proposals for advanced reactors. The natural circulation systems are inherently more unstable than forced circulation ones due to its nonlinear nature and low driving force. Any disturbance, e.g. flashing or boiling inception, in the driving force will affect the flow which in turn will influence the driving force leading to an oscillatory behavior. Owing to safety concerns, flashing instability particularly for advanced boiling water reactors has been broadly investigated, and many test facilities have been constructed in the past. A number of numerical analyses of experimental test cases are available. Nevertheless, there exists a need to update the method from one-dimensional system codes to high-resolution computational fluid dynamics (CFD). In the present work flashing-induced instability behavior and flow pattern in the riser of the GENEVA facility, which is a downscale of a reactor containment passive cooling system, is investigated using the commercial CFD code ANSYS CFX. A two-fluid model is adopted for the unstable turbulent gas-liquid flow, and the HZDR baseline closure is used to model interphase mass, momentum, heat transfer as well as bubble-induced turbulence. The simulated fluid temperature, pressure and local void fraction at different heights of the riser are compared with the measured ones. The limitation and possibility of the CFD technique for such complex two-phase scenarios are discussed, and suggestions for improving the predictability of simulations are made.

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Zhu, Yong, and Eric J. Barth. "Energy-Based Control of a Pneumatic Oscillator With Application to Energy Efficient Hopping Robots." In ASME 2006 International Mechanical Engineering Congress and Exposition. ASMEDC, 2006. http://dx.doi.org/10.1115/imece2006-15015.

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This paper presents an energetically derived control methodology to specify and regulate the frequency and amplitude of oscillatory motion of a pneumatic actuation system. A lossless horizontal pneumatic actuation system with an inertia is energetically shown to represent an oscillator with a stiffness, and hence frequency, related to the equilibrium pressures in the actuator. Following from an analysis of the conservative energy storage elements in the system, a control methodology is derived to sustain a specified frequency and amplitude of oscillation in the presence of energy dissipation. The control strategy takes advantage of the natural passive dynamics of the system to provide much of the required actuation forces, while the remaining forces needed to overcome the energy dissipation present in a non-ideal system with losses are provided by a nonlinear control law for the charging and discharging of the actuator. This control methodology is demonstrated experimentally to provide accurate and repeatable frequency and amplitude control of oscillation in the presence of dissipative forces. Finally, the energetic analysis of the horizontal pneumatic system is extended to the vertical case where gravity is present. This extension provides an energetically efficient hopping control methodology for pneumatically actuated robots.

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Daboin, Jose, and Parisa Saboori. "Effect of Shaking at or Near Resonance of a Simple Head Model on Skull/Brain Connectors." In ASME 2021 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/imece2021-69054.

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Abstract A solid model of a six-month-old child has been developed using average human anatomical characteristics combined with crash test dummy dimensions. The model consisted of a body and limbs, and a neck and head combination with the head being hollow and housing a hemispherical brain. This model was then exposed to a linear sinusoidal input displacement to the chest, and the angular displacement of the skull and brain were observed. The resulting data showed that the oscillatory behavior was a function of frequency, and maximal oscillations existed at a frequency close to the expected natural frequency of the head/neck system, and at a frequency one order of magnitude greater than this frequency. In addition, when a square wave was applied, rather than a sine wave, the resulting oscillation proved to be more violent; and finally, a real input was applied to the model, from previous tests, to discover if a different oscillatory behavior resulted.

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