Articles de revues : « Synchronous dynamics »

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Li, Yi Min, Zhi Yong Hao et Jin Li. « Analysis and Research of Dynamic Characteristics of Synchronous Belt of a Diesel Using Multi-Body Dynamics ». Applied Mechanics and Materials 97-98 (septembre 2011) : 721–25. http://dx.doi.org/10.4028/www.scientific.net/amm.97-98.721.

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The dynamic tension of synchronous belt and pulleys forces are obtained by analyzing the dynamic characteristics of timing drive system of a diesel based on muti-body dynamics. The effects of crankshaft speed fluctuation and other excitations on the dynamics characteristics of synchronous belt are illustrated. After the analysis, it is found that crankshaft speed fluctuation has a great influence on the linear and transversal vibrations of synchronous belt. Comparing the simulation results of the original timing system and the one optimized, it is found that the modal frequency of synchronous belt depends on its span. Therefore it is important to control the span of belt and arrange the tensioner pulley properly for timing system design.

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Shi, Yao Chen, Zhan Guo Li et Xiu Guang Yang. « The Tooth Profile of Car Synchronous Belt Influencing on the Stress Distribution ». Applied Mechanics and Materials 602-605 (août 2014) : 339–41. http://dx.doi.org/10.4028/www.scientific.net/amm.602-605.339.

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This paper aim at the ZA type car synchronous belt, using the CATIA software create the synchronous belt and pulleys 3D model, divide synchronous belt mesh with ANSYS software, and import into the multi-body dynamics software RecurDyn and build up the dynamic simulation model of the car synchronous belt transmission through the MFBD (more flexible body dynamics) techniques. Analyzed the transmission performance of the synchronous belt、contact stress of tooth surface and tension stress. It propose the stress distribution between belt and pulley, and the distribution state of the tensile stress. It provide a digital simulation and design method to design the car synchronous belt tooth shape, analysis the transmission performance and select the material of rubber and the reinforcing cords.

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Pavlova, Olga Nikolaevna, Alexyi Aleksandrovich Anisimov, Alexyi Igorevich Nazimov et Alexyi Nikolaevich Pavlov. « Synchronous Dynamics of Nephrons Ensembles ». Izvestiya of Saratov University. New series. Series : Physics 11, n^o 1 (2011) : 3–10. http://dx.doi.org/10.18500/1817-3020-2011-11-1-3-10.

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YANG, XIAO-SONG, et QUAN YUAN. « EMERGENT CHAOS SYNCHRONIZATION IN NONCHAOTIC CNNS ». International Journal of Bifurcation and Chaos 18, n^o 05 (mai 2008) : 1337–42. http://dx.doi.org/10.1142/s0218127408021026.

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It is shown that emergent chaos synchronization can take place in coupled nonchaotic unit dynamical systems. This is demonstrated by coupling two nonchaotic cellular neural networks, in which the couplings give rise to a synchronous chaotic dynamics and in the meanwhile the synchronous dynamics is globally asymptotically stable, thus chaos synchronization takes place under the suitable couplings.

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Hwang, Yunn Lin, et Van Thuan Truong. « A Synchronous Approach for Numerical Simulation of Machine Tools ». Key Engineering Materials 642 (avril 2015) : 317–22. http://dx.doi.org/10.4028/www.scientific.net/kem.642.317.

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In this paper, a synchronous approach for dynamic simulation of machine tools is described. Computer Aided Engineering (CAE) method models and analyzes a dynamical parameter prototype of machine tools. In which, the flexible structure, interactive movement, non-linear factor effects as well as characteristics of resonance frequencies and mechanical transfer function are considered. The integrating Finite Element Method (FEM), Multi-Body Dynamics (MBD) and control carries out a solution of machine tools simulation for predicting dynamic machine behaviors. The static analysis and modal analysis of components are presented with sample examples. Cybernetic characteristics like Bode diagram and such a controller are implemented for movement tailors. The synchronous approach deduces a practically technical method for machines tools.

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Cirillo, Emilio Nicola Maria, Vanessa Jacquier et Cristian Spitoni. « Metastability of Synchronous and Asynchronous Dynamics ». Entropy 24, n^o 4 (24 mars 2022) : 450. http://dx.doi.org/10.3390/e24040450.

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Metastability is a ubiquitous phenomenon in nature, which interests several fields of natural sciences. Since metastability is a genuine non-equilibrium phenomenon, its description in the framework of thermodynamics and statistical mechanics has progressed slowly for a long time. Since the publication of the first seminal paper in which the metastable behavior of the mean field Curie–Weiss model was approached by means of stochastic techniques, this topic has been largely studied by the scientific community. Several papers and books have been published in which many different spin models were studied and different approaches were developed. In this review, we focus on the comparison between the metastable behavior of synchronous and asynchronous dynamics, namely, stochastic processes in discrete time in which, at each time, either all the spins or one single spin is updated. In particular, we discuss how two different stochastic implementations of the very same Hamiltonian give rise to different metastable behaviors.

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Vasseur, David A., Jeremy W. Fox, Andrew Gonzalez, Rita Adrian, Beatrix E. Beisner, Matthew R. Helmus, Catherine Johnson et al. « Synchronous dynamics of zooplankton competitors prevail in temperate lake ecosystems ». Proceedings of the Royal Society B : Biological Sciences 281, n^o 1788 (7 août 2014) : 20140633. http://dx.doi.org/10.1098/rspb.2014.0633.

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Although competing species are expected to exhibit compensatory dynamics (negative temporal covariation), empirical work has demonstrated that competitive communities often exhibit synchronous dynamics (positive temporal covariation). This has led to the suggestion that environmental forcing dominates species dynamics; however, synchronous and compensatory dynamics may appear at different length scales and/or at different times, making it challenging to identify their relative importance. We compiled 58 long-term datasets of zooplankton abundance in north-temperate and sub-tropical lakes and used wavelet analysis to quantify general patterns in the times and scales at which synchronous/compensatory dynamics dominated zooplankton communities in different regions and across the entire dataset. Synchronous dynamics were far more prevalent at all scales and times and were ubiquitous at the annual scale. Although we found compensatory dynamics in approximately 14% of all combinations of time period/scale/lake, there were no consistent scales or time periods during which compensatory dynamics were apparent across different regions. Our results suggest that the processes driving compensatory dynamics may be local in their extent, while those generating synchronous dynamics operate at much larger scales. This highlights an important gap in our understanding of the interaction between environmental and biotic forces that structure communities.

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Friston, Karl J. « The labile brain. I. Neuronal transients and nonlinear coupling ». Philosophical Transactions of the Royal Society of London. Series B : Biological Sciences 355, n^o 1394 (29 février 2000) : 215–36. http://dx.doi.org/10.1098/rstb.2000.0560.

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In this, the first of three papers, the nature of, and motivation for, neuronal transients is described in relation to characterizing brain dynamics. This paper deals with some basic aspects of neuronal dynamics, interactions, coupling and implicit neuronal codes. The second paper develops neuronal transients and nonlinear coupling in the context of dynamic instability and complexity, and suggests that instability or lability is necessary for adaptive self–organization. The final paper addresses the role of neuronal transients through information theory and the emergence of spatio–temporal receptive fields and functional specialization. By considering the brain as an ensemble of connected dynamic systems one can show that a sufficient description of neuronal dynamics comprises neuronal activity at a particular time and its recent history. This history constitutes a neuronal transient. As such, transients represent a fundamental metric of neuronal interactions and, implicitly, a code employed in the functional integration of brain systems. The nature of transients, expressed conjointly in distinct neuronal populations, reflects the underlying coupling among populations. This coupling may be synchronous (and possibly oscillatory) or asynchronous. A critical distinction between synchronous and asynchronous coupling is that the former is essentially linear and the latter is nonlinear. The nonlinear nature of asynchronous coupling enables the rich, context–sensitive interactions that characterize real brain dynamics, suggesting that it plays a role in functional integration that may be as important as synchronous interactions. The distinction between linear and nonlinear coupling has fundamental implications for the analysis and characterization of neuronal interactions, most of which are predicated on linear (synchronous) coupling (e.g. crosscorrelograms and coherence). Using neuromagnetic data it is shown that nonlinear (asynchronous) coupling is, in fact, more abundant and can be more significant than synchronous coupling.

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Bolotov, Maxim, Tatiana Levanova, Lev Smirnov et Arkady Pikovsky. « Dynamics of disordered heterogeneous chains of phase oscillators ». Cybernetics and Physics, Volume 8, 2019, Number 4 (30 décembre 2019) : 215–21. http://dx.doi.org/10.35470/2226-4116-2019-8-4-215-221.

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We study the problem of robustness of synchronous states to disorder in the chain of phase oscillators with local coupling. The study combines a numerical determination of the existence and stability of synchronous states with an analytical investigation of the role of the phase shift and the level of disorder in the natural frequencies in the destruction of synchrony. We show that the presence of the phase shift facilitates robustness of the synchronous regime, at least up to its certain threshold value.

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Wallach, Avner, et Shimon Marom. « Interactions between network synchrony and the dynamics of neuronal threshold ». Journal of Neurophysiology 107, n^o 11 (1 juin 2012) : 2926–36. http://dx.doi.org/10.1152/jn.00876.2011.

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Synchronous activity impacts on a range of functional brain capacities in health and disease. To address the interrelations between cellular level activity and network-wide synchronous events, we implemented in vitro a recently introduced technique, the response clamp, which enables online monitoring of single neuron threshold dynamics while ongoing network synchronous activity continues uninterrupted. We show that the occurrence of a synchronous network event causes a significant biphasic change in the single neuron threshold. These threshold dynamics are correlated across the neurons constituting the network and are entailed by the input to the neurons rather than by their own spiking (i.e., output) activity. The magnitude of network activity during a synchronous event is correlated with the threshold state of individual neurons at the event's onset. Recovery from the impact of a given synchronous event on the neuronal threshold lasts several seconds and seems to be a key determinant of the time to the next spontaneously occurring synchronous event. Moreover, the neuronal threshold is shown to be correlated with the excitability dynamics of the entire network. We conclude that the relations between the two levels (network activity and the single neuron threshold) should be thought of in terms that emphasize their interactive nature.

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CIANFRANI, FRANCESCO, et GIOVANNI MONTANI. « SYNCHRONOUS QUANTUM GRAVITY ». International Journal of Modern Physics A 23, n^o 08 (30 mars 2008) : 1149–56. http://dx.doi.org/10.1142/s0217751x08040007.

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The implications of restricting the covariance principle within a Gaussian gauge are developed both on a classical and a quantum level. Hence, we investigate the cosmological issues of the obtained Schrödinger Quantum Gravity with respect to the asymptotically early dynamics of a generic Universe. A dualism between time and the reference frame fixing is then inferred.

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Skantzos, N. S., et A. C. C. Coolen. « Random field Ising chains with synchronous dynamics ». Journal of Physics A : Mathematical and General 33, n^o 9 (28 février 2000) : 1841–55. http://dx.doi.org/10.1088/0305-4470/33/9/309.

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Tagamets, M. A., et Barry Horwitz. « Synchronous dynamics for cognitive coordination : But how ? » Behavioral and Brain Sciences 26, n^o 1 (février 2003) : 106–7. http://dx.doi.org/10.1017/s0140525x03450024.

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AbstractAlthough interesting, the hypotheses proposed by Phillips & Silverstein lack unifying structure both in specific mechanisms and in cited evidence. They provide little to support the notion that low-level sensory processing and high-level cognitive coordination share dynamic grouping by synchrony as a common processing mechanism. We suggest that more realistic large-scale modeling at multiple levels is needed to address these issues.

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Dunn, Aaron, Rémi Dingreville, Enrique Martínez et Laurent Capolungo. « Synchronous parallel spatially resolved stochastic cluster dynamics ». Computational Materials Science 120 (juillet 2016) : 43–52. http://dx.doi.org/10.1016/j.commatsci.2016.04.013.

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Hegazy, Y. G., K. I. Saleh et M. A. Badr. « An efficient identifier for synchronous machine dynamics ». European Transactions on Electrical Power 6, n^o 4 (7 septembre 2007) : 275–81. http://dx.doi.org/10.1002/etep.4450060407.

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Deshmukh, Ankosh D., Nitesh D. Shambharkar et Prashant M. Gade. « Effect of a Mode of Update on Universality Class for Coupled Logistic Maps : Directed Ising to Ising Class ». International Journal of Bifurcation and Chaos 31, n^o 03 (15 mars 2021) : 2150042. http://dx.doi.org/10.1142/s0218127421500425.

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Ising model at zero temperature leads to a ferromagnetic state asymptotically. There are two such possible states linked by symmetry, and Glauber–Ising dynamics are employed to reach them. In some stochastic or deterministic dynamical systems, the same absorbing state with [Formula: see text] symmetry is reached. This transition often belongs to the directed Ising (DI) class where dynamic exponents and persistence exponent are different. In asymmetrically coupled sequentially updated logistic maps, the transition belongs to the DI class. We study changes in the nature of transition with an update scheme. Even with the synchronous update, the transition still belongs to the DI class. We also study a synchronous probabilistic update scheme in which each site is updated with the probability [Formula: see text]. The order parameter decays with an exponent [Formula: see text] in this scheme. Nevertheless, the dynamic exponent [Formula: see text] is less than [Formula: see text] even for small values of [Formula: see text] indicating a very slow crossover to the Ising class. However, with a random asynchronous update, we recover [Formula: see text]. In the presence of feedback, synchronous update leads to a transition in the DI universality class which changes to Ising class for synchronous probabilistic update.

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Santos, Bruno A., Xabier E. Barandiaran et Philip Husbands. « Synchrony and phase relation dynamics underlying sensorimotor coordination ». Adaptive Behavior 20, n^o 5 (11 juillet 2012) : 321–36. http://dx.doi.org/10.1177/1059712312451859.

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Synchronous oscillations have become a widespread hypothetical “mechanism” to explain how brain dynamics give rise to neural functions. By focusing on synchrony one leaves the phase relations during moments of desynchronous oscillations either without a clear functional role or with a secondary role such as a transition between functionally “relevant” synchronized states. In this work, rather than studying synchrony we focus on desynchronous oscillations and investigate their functional roles in the context of a sensorimotor coordination task. In particular, we address the questions: a) how does the informational content of the sensorimotor activity present in a complete dynamical description of phase relations change as such a description is reduced to the dynamics of synchronous oscillations? and b) to what extent are desynchronous oscillations as causally relevant as synchronous ones to the generation of functional sensorimotor coordination? These questions are addressed with a model of a simulated agent performing a functional sensorimotor coordination task controlled by an oscillatory network. The results suggest that: i) desynchronized phase relations carry as much information about sensorimotor activity as synchronized phase relations; and ii) phase relations between oscillators with near-zero frequency difference carry a relatively higher causal relevance than the rest of the phase relations to the sensorimotor coordination; however, overall a privileged functional causal contribution can not be attributed to either synchronous or desynchronous oscillations.

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Liang, Shi-Dong, Haoqi Li et Yuefan Deng. « Mechanism of dynamic phase transition and synchronous stability in Hindmarsh–Rose neuronal network ». International Journal of Modern Physics B 32, n^o 28 (7 novembre 2018) : 1850308. http://dx.doi.org/10.1142/s0217979218503083.

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The neuronal dynamics plays an important role in understanding the neurological phenomena. We study the mechanism of the dynamic phase transition and its Lyapunov stability of a single Hindmarsh–Rose (HR) neuronal model. We propose an index [Formula: see text] to express the dynamical phase of the HR neurons. When [Formula: see text] the neuron is in the pure resting state, and when [Formula: see text] the neuron closes to the pure spiking phase, while when [Formula: see text] the neuron runs in the bursting phase. Based on this method, we investigate numerically the phase diagram of the HR neuronal model in the parameter space. We find that two mechanisms governed the HR neuronal dynamic phase transition, the phase transition and crossover transition in the different regions of the parameter space. Moreover, we analyze the equilibrium point stability of the HR neuronal model based on the Lyapunov stability method. We study the synchronous stability of the HR neuronal network based on the master stability function method and give the phase diagrams of the maximum Lyapunov exponents in the parameter space of networks. The regions of the synchronous stabilities in the parameter space depend on the couplings of the HR neurons of the membrane potential and the flux of the fast ion channel between the HR neurons. These results help to understand the HR neuronal dynamics and the synchronous stability of the HR neuronal networks.

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Rogers, Tanya L., et Stephan B. Munch. « Hidden similarities in the dynamics of a weakly synchronous marine metapopulation ». Proceedings of the National Academy of Sciences 117, n^o 1 (23 décembre 2019) : 479–85. http://dx.doi.org/10.1073/pnas.1910964117.

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Populations of many marine species are only weakly synchronous, despite coupling through larval dispersal and exposure to synchronous environmental drivers. Although this is often attributed to observation noise, factors including local environmental differences, spatially variable dynamics, and chaos might also reduce or eliminate metapopulation synchrony. To differentiate spatially variable dynamics from similar dynamics driven by spatially variable environments, we applied hierarchical delay embedding. A unique output of this approach, the “dynamic correlation,” quantifies similarity in intrinsic dynamics of populations, independently of whether their abundance is correlated through time. We applied these methods to 17 populations of blue crab (Callinectes sapidus) along the US Atlantic coast and found that their intrinsic dynamics were broadly similar despite largely independent fluctuations in abundance. The weight of evidence suggests that the latitudinal gradient in temperature, filtered through a unimodal response curve, is sufficient to decouple crab populations. As unimodal thermal performance is ubiquitous in ectotherms, we suggest that this may be a general explanation for the weak synchrony observed at large distances in many marine species, although additional studies are needed to test this hypothesis.

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PASEMANN, FRANK. « SYNCHRONOUS AND ASYNCHRONOUS CHAOS IN COUPLED NEUROMODULES ». International Journal of Bifurcation and Chaos 09, n^o 10 (octobre 1999) : 1957–68. http://dx.doi.org/10.1142/s0218127499001425.

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The parametrized time-discrete dynamics of two recurrently coupled neuromodules is studied analytically and by computer simulations. Conditions for the existence of synchronized dynamics are derived and periodic as well as quasiperiodic and chaotic attractors constrained to a synchronization manifold M are observed. Stability properties of the synchronized dynamics is discussed by using Lyapunov exponents parallel and transversal to the synchronization manifold. Simulation results are presented for selected sets of parameters. It is observed that locally stable synchronous dynamics often coexists with asynchronous periodic, quasiperiodic or even chaotic attractors.

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Long, Yi, et Xiao Jun Yang. « Robust Adaptive Sliding Mode Synchronous Control for a Planar Redundantly Actuated Parallel Manipulator ». Advanced Materials Research 605-607 (décembre 2012) : 1583–88. http://dx.doi.org/10.4028/www.scientific.net/amr.605-607.1583.

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To obtain better trajectory tracking, a new synchronous control with sliding mode surface is proposed. Based on Kane equation, the dynamics model of a planar 2-DOF redundantly actuated parallel mechanism was formulated. With trajectory contour error, the synchronization error was defined and the sliding surface was determined. After dynamic equation linearization, a robust adaptive sliding mode synchronous controller was designed with stability analysis. After Matlab simulation, figures of tracking errors and synchronization errors changing with time compared with computed torque method were plotted. Results show that the robust adaptive sliding mode synchronous control can be able to achieve good trajectory tracking compared with computed torque controller.

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NEMES, LÁSZLÓ, et LEON O. CHUA. « THE SPATIOTEMPORAL PRISONER'S DILEMMA ». International Journal of Bifurcation and Chaos 10, n^o 07 (juillet 2000) : 1623–44. http://dx.doi.org/10.1142/s021812740000102x.

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A novel platform, the cellular neural network universal machine (CNN-UM) model is proposed to simulate the spatial prisoner's dilemma (SPD) game introduced in [Nowak & May, 1992]. The application of CNN is motivated by both its high conformity with the modeled natural phenomena (analog dynamics) and its superior speed enabling the exploration of the SPD's vast parameter space. Several models are shown as examples of CNN implementation. In particular, a synchronously updated model is introduced using strategy based on best individual strategy (BIS). A new synchronous model is shown based on better average strategy (BAS). Stemming from the CNN implementation of synchronous SPD an asynchronous model has been developed employing BIS, and the survival of clusters of cooperating individuals is demonstrated. This seems to contradict the view elaborated in [Huberman & Glance 1993] claiming that the viability of cooperation is an artifact of synchronous updating in SPD.

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Zhang, Yao, Jiajun Mou, Fan Zhang et Na Huang. « Modeling and Stability Analysis Based on Internal Voltage Dynamics in Synchronverter ». Electronics 12, n^o 3 (31 janvier 2023) : 700. http://dx.doi.org/10.3390/electronics12030700.

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With the large-scale centralized penetration of renewable energy represented by wind turbine and photovoltaic power generation, the equivalent inertia and synchronous torque of traditional power grids have decreased, which is worsening the frequency dynamics and threatening the stability and reliability of power grids. Virtual synchronous generators (VSGs) are a type of grid-friendly inverter in microgrids (MGs) that mimic rotational synchronous generators (SGs) to maintain system stability with the increasing penetration of power electronic converters. In this paper, the stability analysis method of one type of VSG, synchronverter, is investigated based on internal voltage dynamics. The torque components affecting the stability mechanism of synchronizing, inertia, and damping torque is introduced, which offers a physical insight into transient stability and dynamic performance. Insufficiency in either damping or synchronizing torque would increase the unstable possibility. The characterization method of stability mechanisms can be illustrated by the phasor diagram of synchronverter internal voltage. Some cases under different disturbances which change the pattern of synchronizing and damping torque and in turn influence the internal voltage dynamics of synchronverters, are also discussed. In addition, an auxiliary correction control loop is proposed and added in the synchronverter control loop to enhance the robustness of the synchronverter against disturbances. The tunable coefficient of the correction loop is analyzed based on the internal voltage method. Simulation results verify the validity of the internal voltage stability method in synchronverters.

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Forte, N., F. Binda, A. Contestabile, F. Benfenati et P. Baldelli. « Synapsin I Synchronizes GABA Release in Distinct Interneuron Subpopulations ». Cerebral Cortex 30, n^o 3 (30 août 2019) : 1393–406. http://dx.doi.org/10.1093/cercor/bhz174.

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Abstract Neurotransmitters can be released either synchronously or asynchronously with respect to action potential timing. Synapsins (Syns) are a family of synaptic vesicle (SV) phosphoproteins that assist gamma-aminobutyric acid (GABA) release and allow a physiological excitation/inhibition balance. Consistently, deletion of either or both Syn1 and Syn2 genes is epileptogenic. In this work, we have characterized the effect of SynI knockout (KO) in the regulation of GABA release dynamics. Using patch-clamp recordings in hippocampal slices, we demonstrate that the lack of SynI impairs synchronous GABA release via a reduction of the readily releasable SVs and, in parallel, increases asynchronous GABA release. The effects of SynI deletion on synchronous GABA release were occluded by ω-AgatoxinIVA, indicating the involvement of P/Q-type Ca2+channel-expressing neurons. Using in situ hybridization, we show that SynI is more expressed in parvalbumin (PV) interneurons, characterized by synchronous release, than in cholecystokinin or SOM interneurons, characterized by a more asynchronous release. Optogenetic activation of PV and SOM interneurons revealed a specific reduction of synchronous release in PV/SynIKO interneurons associated with an increased asynchronous release in SOM/SynIKO interneurons. The results demonstrate that SynI is differentially expressed in interneuron subpopulations, where it boosts synchronous and limits asynchronous GABA release.

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Stowell, Frank, et Shavindrie Cooray. « Addressing Team Dynamics in Virtual Teams ». International Journal of Information Technologies and Systems Approach 9, n^o 1 (janvier 2016) : 32–53. http://dx.doi.org/10.4018/ijitsa.2016010103.

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Computer Mediated Communication (CMC) is providing businesses with the means of assembling virtual teams comprising of members in diverse locations. However research shows that virtual team dynamics are different from face to face dynamics. Recent research adds force to the view that conflicts are more prevalent within virtual teams since participants are less likely to change their initial points of view when discussions are held virtually. This insight has implications for IS development since many IS are developed by virtual project teams. It is relevant to systems analysis since according to systems thinkers the process should include a discussion about alternative points of view leading to a group level shared view of the situation under analysis. If recent research is taken into account then conflict resolution in virtual teams is difficult which raises doubts about whether a group level view of a situation can be reached during systems analysis. In this paper, the authors strive to identify challenges associated with the application of soft methods in synchronous virtual teams since a review of literature shows that soft methods have not been used previously in synchronous virtual teams. The authors also explore if concerns about conflicts in synchronous virtual teams can be overcome through the use of soft systems methods.

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Zhang, WanFu, JianGang Yang, QingShui Gao et Jie Li. « Reducing the influence of partial admission on unstable synchronous vibration of turbines by bearing elevation optimization ». Proceedings of the Institution of Mechanical Engineers, Part C : Journal of Mechanical Engineering Science 228, n^o 1 (21 mars 2013) : 56–66. http://dx.doi.org/10.1177/0954406213481715.

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To investigate the rotor-bearing dynamics and solve the unstable synchronous vibration problem under partial admission conditions in axial steam turbines, a three-dimensional computational fluid dynamics model of the governing stage for a 350 MW turbogenerator unit was established. Steam force under different partial admission cases was calculated. Results show that the uneven steam force in the horizontal direction was fairly as strong as that in the vertical direction. The maximal horizontal steam force was about 40% of the high intermediate pressure cylinder rotor weight. Synchronous vibration faults caused by partial admission may occur in practice. The finite element model was further built to analyze the rotor-bearing dynamics under partial admission conditions. Large fluctuation of the synchronous vibration was observed during the variation of control valve sequence. Finally, the effect of bearing elevation on the rotor-bearing dynamics was studied. The sensitivity of bearing load varies for different bearing elevations. An effective solution to the unstable synchronous vibration faults caused by partial admission was achieved by optimizing the distribution of bearing elevation. A relevant case was presented through practical test.

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Prudence Marthange, Yagbanga Niella, Shangzhi Li et Shangjiang Guo. « Synchronous dynamics of a delayed two-coupled oscillator ». Electronic Journal of Qualitative Theory of Differential Equations, n^o 52 (2017) : 1–20. http://dx.doi.org/10.14232/ejqtde.2017.1.52.

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Abad, E., G. Nicolis, Jonathan L. Bentz et John J. Kozak. « Synchronous vs. asynchronous dynamics of diffusion-controlled reactions ». Physica A : Statistical Mechanics and its Applications 326, n^o 1-2 (août 2003) : 69–87. http://dx.doi.org/10.1016/s0378-4371(03)00272-3.

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Lumer, Erik D., et Grégoire Nicolis. « Synchronous versus asynchronous dynamics in spatially distributed systems ». Physica D : Nonlinear Phenomena 71, n^o 4 (mars 1994) : 440–52. http://dx.doi.org/10.1016/0167-2789(94)90010-8.

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Bowman, Jeff, Dennis Donovan et Richard C. Rosatte. « NUMERICAL RESPONSE OF FISHERS TO SYNCHRONOUS PREY DYNAMICS ». Journal of Mammalogy 87, n^o 3 (juin 2006) : 480–84. http://dx.doi.org/10.1644/05-mamm-a-202r2.1.

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Rybak, A. T., A. R. Temirkanov et O. V. Lyakhnitskaya. « Dynamics of Synchronous Hydromechanical Drive in Mobile Machine ». Russian Engineering Research 38, n^o 9 (septembre 2018) : 702–4. http://dx.doi.org/10.3103/s1068798x18090253.

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He, Ren, et Qingzhen Han. « Dynamics and Stability of Permanent-Magnet Synchronous Motor ». Mathematical Problems in Engineering 2017 (2017) : 1–8. http://dx.doi.org/10.1155/2017/4923987.

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The aim of this article is to explore the dynamic characteristics and stability of the permanent-magnet synchronous motor (PMSM). PMSM equilibrium local stability condition and Hopf bifurcation condition, pitchfork bifurcation condition, and fold bifurcation condition have been derived by using the Routh-Hurwitz criterion and the bifurcation theory, respectively. Bifurcation curves of the equilibrium with single and double parameters are obtained by continuation method. Numerical simulations not only confirm the theoretical analysis results but also show one kind of codimension-two-bifurcation points of the equilibrium. PMSM, with or without external load, can exhibit rich dynamic behaviors in different parameters regions. It is shown that if unstable equilibrium appears in the parameters regions, the PMSM may not be able to work stably. To ensure the PMSMs work stably, the inherent parameters should be designed in the region which has only one stable equilibrium.

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Varghese, A., P. W. Sauer et M. A. Pai. « Synchronous machine block diagram analysis with fast dynamics ». International Journal of Electrical Power & ; Energy Systems 11, n^o 4 (octobre 1989) : 239–47. http://dx.doi.org/10.1016/0142-0615(89)90034-3.

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Zhang, Yunfei, Can Zhao, Bin Dai et Zhiheng Li. « Dynamic Simulation of Permanent Magnet Synchronous Motor (PMSM) Electric Vehicle Based on Simulink ». Energies 15, n^o 3 (3 février 2022) : 1134. http://dx.doi.org/10.3390/en15031134.

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As an important component of vehicle design and energy conservation, electric vehicle dynamics simulation is essential, especially under complicated testing conditions. The current commercial vehicle simulation software is mostly used for fuel vehicle dynamics simulation, which lacks accurate electric powertrain parts and open sources. To address this problem, this paper proposes an open-source and flexible vehicle dynamics simulation platform that includes 27 degrees of freedom (DOFs) based on Simulink, which can compatibly support both traditional vehicle dynamics simulations and electric vehicle dynamics simulations. In addition, the platform can support module customization, which is convenient for researchers. Although this platform still needs some iterations to reach industrial and commercial standards, it can already achieve parameter consistency under the stability demands in general scenarios. We believe this work should receive research attention and participation to provide lower thresholds and more references to the dynamic simulation of electric vehicles to reduce vehicle energy consumption.

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Kurilova, E. V., et M. P. Kulakov. « STUDY OF CONDITIONS FOR COMPLEX DYNAMIC REGIMES IN THE FAST-SLOW MODEL OF COMMUNITIES COUPLED BY MIGRATION ». Regional problems 25, n^o 3 (2022) : 174–76. http://dx.doi.org/10.31433/2618-9593-2022-25-3-174-176.

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The paper deals with the study of dynamics of fast-slow system consisting of two non-identical communities «predator – prey» coupled by migration. We study the mechanisms that lead to the complex space-time structures in the case of a weak coupling between very different communities. The community dynamics in this case is non-synchronous or partially synchronous.

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Böttcher, Philipp C., Dirk Witthaut et Leonardo Rydin Gorjão. « Dynamic stability of electric power grids : Tracking the interplay of the network structure, transmission losses, and voltage dynamics ». Chaos : An Interdisciplinary Journal of Nonlinear Science 32, n^o 5 (mai 2022) : 053117. http://dx.doi.org/10.1063/5.0082712.

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Dynamic stability is imperative for the operation of the electric power system. This article provides analytical results and effective stability criteria focusing on the interplay of network structures and the local dynamics of synchronous machines. The results are based on an extensive linear stability analysis of the third-order model for synchronous machines, comprising the classical power-swing equations and the voltage dynamics. The article addresses the impact of Ohmic losses, which are important in distribution and microgrids but often neglected in analytical studies. We compute the shift of the stability boundaries to leading order, and thus provide a detailed qualitative picture of the impact of Ohmic losses. A subsequent numerical study of the criteria is presented, without and with resistive terms, to test how tight the derived analytical results are.

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Shi, Yao Chen, Zhan Guo Li et Qi Long Liu. « Automotive Synchronous Belt Transmission Stationarity Simulation Analysis Based on the Rigid-Flexible Coupling ». Applied Mechanics and Materials 602-605 (août 2014) : 342–44. http://dx.doi.org/10.4028/www.scientific.net/amm.602-605.342.

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In this paper, Using rigid-flexible coupling method the auto synchronous belt drive system dynamics model is established. We can make the rigid-flexible coupling analysis of auto synchronous belt drive system through Recurdyn, designed and auto synchronous belt vibration displacement measurement device was developed, measuring the midpoint of the belt in the process of synchronous belt transmission vibration curve of change over time. Has an important value to improve auto synchronous belt transmission stability and reduce the transmission noise.

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He, Xiang Xin, Jian Guo Li et Yue Hua Pang. « Modeling and Simulation of Electromechanical Coupling Dynamics for Permanent Magnet Synchronous AC Servomotor ». Advanced Materials Research 418-420 (décembre 2011) : 2106–9. http://dx.doi.org/10.4028/www.scientific.net/amr.418-420.2106.

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Lagrange-Maxwell equations and Park transform are adopted based on electrical and mechanical energy equations consisting of servomotor parameters. Lagrange-Maxwell equations are transformed from three-phase stator reference coordinates to two-phase rotor reference coordinates. Electromechanical coupling dynamics equations of permanent magnet synchronous servomotor in two-phase reference coordinates are obtained. In this dynamical modeling method of electromechanical coupling system, to establish dynamical differential equations needs to measure amplitude of the flux induced by the permanent magnets and the winding's inductance in dq0 reference of the motor but needs not to measure the size of magnetic circuit. The equations deduced is terse, efficient, and the equations easy to use. Electromechanical coupling dynamics system, servomotor is simulated. Simulation results show that the electromechanical coupling dynamics equations deduced for servomotor are correct, and current control schemes are reasonable.

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Delisle, J. B., A. C. M. Correia, A. Leleu et P. Robutel. « Spin dynamics of close-in planets exhibiting large transit timing variations ». Astronomy & ; Astrophysics 605 (septembre 2017) : A37. http://dx.doi.org/10.1051/0004-6361/201730755.

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We study the spin evolution of close-in planets in compact multi-planetary systems. The rotation period of these planets is often assumed to be synchronous with the orbital period due to tidal dissipation. Here we show that planet-planet perturbations can drive the spin of these planets into non-synchronous or even chaotic states. In particular, we show that the transit timing variation (TTV) is a very good probe to study the spin dynamics, since both are dominated by the perturbations of the mean longitude of the planet. We apply our model to KOI-227 b and Kepler-88 b, which are both observed undergoing strong TTVs. We also perform numerical simulations of the spin evolution of these two planets. We show that for KOI-227 b non-synchronous rotation is possible, while for Kepler-88 b the rotation can be chaotic.

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Li, Ming, Zi Gang Li et Ping Xue. « Nonlinear Dynamic Behaviors of Rotor System with Misaligned Journal Bearings ». Applied Mechanics and Materials 271-272 (décembre 2012) : 1032–38. http://dx.doi.org/10.4028/www.scientific.net/amm.271-272.1032.

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The dynamic modeling of a rotor system on misaligned journal bearings is discussed and its nonlinear dynamic behaviors are considered in this paper. Firstly, a dynamic model of six degrees of freedom system is established under the conditions of the long bearings, small bearing misalignment and mass unbalance. Then, the nonlinear dynamics of the rotor-bearing system, such as the displacement response and its frequency spectrum, rotor orbit and its Poincare map are analyzed by the Runge-Kutta method. The results show that at low speed the steady-state responses of the rotor system in lateral direction is synchronous, as the speed increases a serious of bifurcation phenomena and chaotic oscillations occur. In many cases, there exist the integer multiples components of the rotating speed except the synchronous one in displacement responses.

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Ding, Q., et A. Y. T. Leung. « Numerical and Experimental Investigations on Flexible Multi-bearing Rotor Dynamics ». Journal of Vibration and Acoustics 127, n^o 4 (7 juillet 2004) : 408–15. http://dx.doi.org/10.1115/1.1898336.

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An experimental test rig is built to verify the dynamics of a multi-bearing rotor. It consists of two flexibly coupled shafts and is connected to a motor at one end via a flexible coupling. Each of the shafts is supported at the ends by two hydrodynamic bearings and is attached with two disks with equal and unequal masses, respectively. The mathematical model of the test rig is developed and is simulated numerically. The non-stationary dynamic responses of the system during speed-up with a constant angular acceleration are shown, respectively, by the non-stationary bifurcation diagrams, the selected time flows, and the spectrum cascades. Experiments are then carried out on the test rig. Generally, the numerical results are verified qualitatively by the experiments. Both results indicate that the non-synchronous whirls of the two shafts influence each other when flexibly coupled together. In particular, a new phenomenon is found for the four-bearing rotor system: the pre-existing non-synchronous whirl/whip resulted from the instability of one shaft can activate the onset of oil instability of another shaft. In the theoretical simulation, this phenomenon represents the rapid increase of the non-synchronous whirl orbit, whereas in the experiment, it represents the simultaneous existence of two whirl/whip frequencies in the spectra.

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Zhong, You Kun. « Design of Synchronous Machine Model Based on PRO/E and Dynamic Simulation ». Applied Mechanics and Materials 246-247 (décembre 2012) : 1220–25. http://dx.doi.org/10.4028/www.scientific.net/amm.246-247.1220.

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With the increasing of the number of cars, people are also getting higher and higher demands on the performance of the car, and especially pay attention to the improvement and optimization of automobile transmission system. The transmission is a key part of automobile transmission system, and transmission performance and stability depend on the synchronous machine, so in order to make the vehicle transmission system with higher efficiency, it is necessary to study the synchronous machine. On the basis of elaborating synchronous machine working principle, the use of dynamics theory to establish mathematical model of synchronous machine system, and to carry out the simulation of synchronous machine three-dimensional model in PRO/E environment, then the use of virtual prototype technology to optimize the parameters of synchronous machine, thereby improving the performance of synchronous machine.

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Vittek, Ján, Slavomír Seman et Daniel Vaňko. « Sensorless control of synchronous motor drive with forced dynamics ». Communications - Scientific letters of the University of Zilina 1, n^o 3 (30 septembre 1999) : 13–22. http://dx.doi.org/10.26552/com.c.1999.3.13-22.

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MacMinn, Stephen R., et Robert J. Thomas. « Microprocessor Simulation of Synchronous Machine Dynamics in Real-Time ». IEEE Power Engineering Review PER-6, n^o 8 (août 1986) : 49–50. http://dx.doi.org/10.1109/mper.1986.5527801.

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叶, 正伟. « Stochastic Dynamics Analysis of Permanent Magnet Synchronous Motor Model ». Advances in Applied Mathematics 09, n^o 04 (2020) : 539–50. http://dx.doi.org/10.12677/aam.2020.94065.

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Jing, Zhujun, Chang Yu et Guanrong Chen. « Complex dynamics in a permanent-magnet synchronous motor model☆ ». Chaos, Solitons & ; Fractals 22, n^o 4 (novembre 2004) : 831–48. http://dx.doi.org/10.1016/j.chaos.2004.02.054.

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Kanter, I. « Synchronous or asynchronous parallel dynamics. Which is more efficient ? » Physica D : Nonlinear Phenomena 42, n^o 1-3 (juin 1990) : 273–80. http://dx.doi.org/10.1016/0167-2789(90)90082-z.

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CHIAPPALONE, MICHELA, ALESSANDRO VATO, LUCA BERDONDINI, MILENA KOUDELKA-HEP et SERGIO MARTINOIA. « NETWORK DYNAMICS AND SYNCHRONOUS ACTIVITY IN CULTURED CORTICAL NEURONS ». International Journal of Neural Systems 17, n^o 02 (avril 2007) : 87–103. http://dx.doi.org/10.1142/s0129065707000968.

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Neurons extracted from specific areas of the Central Nervous System (CNS), such as the hippocampus, the cortex and the spinal cord, can be cultured in vitro and coupled with a micro-electrode array (MEA) for months. After a few days, neurons connect each other with functionally active synapses, forming a random network and displaying spontaneous electrophysiological activity. In spite of their simplified level of organization, they represent an useful framework to study general information processing properties and specific basic learning mechanisms in the nervous system. These experimental preparations show patterns of collective rhythmic activity characterized by burst and spike firing. The patterns of electrophysiological activity may change as a consequence of external stimulation (i.e., chemical and/or electrical inputs) and by partly modifying the "randomness" of the network architecture (i.e., confining neuronal sub-populations in clusters with micro-machined barriers). In particular we investigated how the spontaneous rhythmic and synchronous activity can be modulated or drastically changed by focal electrical stimulation, pharmacological manipulation and network segregation. Our results show that burst firing and global synchronization can be enhanced or reduced; and that the degree of synchronous activity in the network can be characterized by simple parameters such as cross-correlation on burst events.

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Xu, Fei, Jiqian Zhang, Tingting Fang, Shoufang Huang et Maosheng Wang. « Synchronous dynamics in neural system coupled with memristive synapse ». Nonlinear Dynamics 92, n^o 3 (20 février 2018) : 1395–402. http://dx.doi.org/10.1007/s11071-018-4134-0.

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Zharov, V. P., et A. T. Rybak. « Modeling the synchronous hydromechanical system and analyzing its dynamics ». Russian Engineering Research 27, n^o 5 (mai 2007) : 283–87. http://dx.doi.org/10.3103/s1068798x07050103.

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