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Literatura académica sobre el tema "Multi-Scale nonlinear dynamics"

Autor: Grafiati

Publicado: 14 de diciembre de 2024

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Artículos de revistas sobre el tema "Multi-Scale nonlinear dynamics"

Sivapalan, Murugesu, Praveen Kumar y Daniel Harris. "Nonlinear propagation of multi-scale dynamics through hydrologic subsystems". Advances in Water Resources 24, n.º 9-10 (noviembre de 2001): 935–40. http://dx.doi.org/10.1016/s0309-1708(01)00028-8.

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LAMARQUE, C. H., A. TURE SAVADKOOHI, E. ETCHEVERRIA y Z. DIMITRIJEVIC. "MULTI-SCALE DYNAMICS OF TWO COUPLED NONSMOOTH SYSTEMS". International Journal of Bifurcation and Chaos 22, n.º 12 (diciembre de 2012): 1250295. http://dx.doi.org/10.1142/s0218127412502951.

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Dynamical behavior of a nonsmooth master system which is coupled to a nonsmooth Nonlinear Energy Sink (NES) during free and forced oscillations is studied analytically and numerically. Invariant manifolds of the system and their stable zones at different time scales are revealed and finally application of coupled nonsmooth NES to the passive control process of the main nonsmooth system is highlighted.

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Bartelt, Matthias y Michael Groß. "Galerkin-based multi-scale time integration for nonlinear structural dynamics". PAMM 14, n.º 1 (diciembre de 2014): 215–16. http://dx.doi.org/10.1002/pamm.201410095.

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Wu, Zhe, Guang Yang, Qiang Zhang, Shengyue Tan y Shuyong Hou. "Information Dynamic Correlation of Vibration in Nonlinear Systems". Entropy 22, n.º 1 (31 de diciembre de 2019): 56. http://dx.doi.org/10.3390/e22010056.

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In previous studies, information dynamics methods such as Von Neumann entropy and Rényi entropy played an important role in many fields, covering both macroscopic and microscopic studies. They have a solid theoretical foundation, but there are few reports in the field of mechanical nonlinear systems. So, can we apply Von Neumann entropy and Rényi entropy to study and analyze the dynamic behavior of macroscopic nonlinear systems? In view of the current lack of suitable methods to characterize the dynamics behavior of mechanical systems from the perspective of nonlinear system correlation, we propose a new method to describe the nonlinear features and coupling relationship of mechanical systems. This manuscript verifies the above hypothesis by using a typical chaotic system and a real macroscopic physical nonlinear system through theory and practical methods. The nonlinear vibration correlation in multi-body mechanical systems is very complex. We propose a full-vector multi-scale Rényi entropy for exploring the chaos and correlation between the dynamic behaviors of mechanical nonlinear systems. The research results prove the effectiveness of the proposed method in modal identification, system dynamics evolution and fault diagnosis of nonlinear systems. It is of great significance to extend these studies to the field of mechanical nonlinear system dynamics.

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KOVALEV, VLADIMIR F. "LIE GROUP ANALYSIS FOR MULTI-SCALE PLASMA DYNAMICS". Journal of Nonlinear Mathematical Physics 18, sup1 (enero de 2011): 163–75. http://dx.doi.org/10.1142/s1402925111001349.

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KUSKE, R. "MULTI-SCALE DYNAMICS IN STOCHASTIC DELAY DIFFERENTIAL EQUATIONS WITH MULTIPLICATIVE NOISE". Stochastics and Dynamics 05, n.º 02 (junio de 2005): 233–46. http://dx.doi.org/10.1142/s0219493705001390.

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We apply multi-scale analysis to stochastic delay-differential equations with multiplicative or parametric noise, deriving approximate stochastic equations for the amplitudes of oscillatory solutions near critical delays. Reduced equations for the envelope of the oscillations provides an efficient analysis of the dynamics by separating the influence of the noise from the intrinsic oscillations over long time scales. We show how this analysis can be used to compute Lyapunov exponents and extended to nonlinear models where the noise has additional resonances.

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Quaranta, Giuseppe, Giovanni Formica, J. Tenreiro Machado, Walter Lacarbonara y Sami F. Masri. "Understanding COVID-19 nonlinear multi-scale dynamic spreading in Italy". Nonlinear Dynamics 101, n.º 3 (agosto de 2020): 1583–619. http://dx.doi.org/10.1007/s11071-020-05902-1.

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Abstract The outbreak of COVID-19 in Italy took place in Lombardia, a densely populated and highly industrialized northern region, and spread across the northern and central part of Italy according to quite different temporal and spatial patterns. In this work, a multi-scale territorial analysis of the pandemic is carried out using various models and data-driven approaches. Specifically, a logistic regression is employed to capture the evolution of the total positive cases in each region and throughout Italy, and an enhanced version of a SIR-type model is tuned to fit the different territorial epidemic dynamics via a differential evolution algorithm. Hierarchical clustering and multidimensional analysis are further exploited to reveal the similarities/dissimilarities of the remarkably different geographical epidemic developments. The combination of parametric identifications and multi-scale data-driven analyses paves the way toward a closer understanding of the nonlinear, spatially nonuniform epidemic spreading in Italy.

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Knar, Zakaria, Jean-Jacques Sinou, Sébastien Besset y Vivien Clauzon. "An Adapted Two-Steps Approach to Simulate Nonlinear Vibrations of Solid Undergoing Large Deformation in Contact with Rigid Plane—Application to a Grooved Cylinder". Applied Sciences 12, n.º 3 (28 de enero de 2022): 1447. http://dx.doi.org/10.3390/app12031447.

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Simulating the full dynamic response of a rolling sculpted tire requires not only taking into account various non-linearities but also considering the multi-scale nature of the dynamic response itself. On one hand, there is the macroscopic rolling dynamic behavior that operates around the rotating frequency with relatively high amplitudes. On the other hand, the vibratory response operates in a larger frequency window with relatively low amplitudes. In contrast to a straightforward strategy that consists of using an energy-conserving stable time integrator to predict the multi-scale dynamic response, the proposed strategy is based on a two-steps approach to separate the dynamics operating at different scales. This methodology is applied to simulate the nonlinear vibrations of a hyperelastic solid undergoing large deformations in contact with a rigid plane. In order to illustrate the potential of the proposed numerical method, the nonlinear vibrations response of a grooved cylinder rolling on a rigid plane is investigated.

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Rundle, J. B., D. L. Turcotte, P. B. Rundle, G. Yakovlev, R. Shcherbakov, A. Donnellan y W. Klein. "Pattern dynamics, pattern hierarchies, and forecasting in complex multi-scale earth systems". Hydrology and Earth System Sciences Discussions 3, n.º 3 (20 de junio de 2006): 1045–69. http://dx.doi.org/10.5194/hessd-3-1045-2006.

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Abstract. Catastrophic disasters afflicting human society are often triggered by tsunamis, earthquakes, widespread flooding, and weather and climate events. As human populations increasingly move into geographic areas affected by these earth system hazards, forecasting the onset of these large and damaging events has become increasingly urgent. In this paper we consider the fundamental problem of forecasting in complex multi-scale earth systems when the basic dynamical variables are either unobservable or incompletely observed. In such cases, the forecaster must rely on incompletely determined, but "tunable" models to interpret observable space-time patterns of events. The sequence of observable patterns constitute an apparent pattern dynamics, which is related to the underlying but hidden Newtonian dynamics by a complex dimensional reduction process. As an example, we examine the problem of earthquakes, which must utilize current and past observations of observables such as seismicity and surface strain to produce forecasts of future activity. We show that numerical simulations of earthquake fault systems are needed in order to relate the fundamentally unobservable nonlinear dynamics to the readily observable pattern dynamics. We also show that the space-time patterns produced by the simulations lead to a scale-invariant hierarchy of patterns, similar to other nonlinear systems. We point out that a similar program of simulations has been very successful in weather forecasting, in which current and past observations of weather patterns are routinely extrapolated forward in time via numerical simulations in order to forecast future weather patterns.

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Rundle, J. B., D. L. Turcotte, P. B. Rundle, R. Shcherbakov, G. Yakovlev, A. Donnellan y W. Klein. "Pattern dynamics, pattern hierarchies, and forecasting in complex multi-scale earth systems". Hydrology and Earth System Sciences 10, n.º 6 (30 de octubre de 2006): 789–96. http://dx.doi.org/10.5194/hess-10-789-2006.

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Abstract. Catastrophic disasters afflicting human society are often triggered by tsunamis, earthquakes, widespread flooding, and weather and climate events. As human populations increasingly move into geographic areas affected by these earth system hazards, forecasting the onset of these large and damaging events has become increasingly urgent. In this paper we consider the fundamental problem of forecasting in complex multi-scale earth systems when the basic dynamical variables are either unobservable or incompletely observed. In such cases, the forecaster must rely on incompletely determined, but "tunable" models to interpret observable space-time patterns of events. The sequence of observable patterns constitute an apparent pattern dynamics, which is related to the underlying but hidden dynamics by a complex dimensional reduction process. As an example, we examine the problem of earthquakes, which must utilize current and past observations of observables such as seismicity and surface strain to produce forecasts of future activity. We show that numerical simulations of earthquake fault systems are needed in order to relate the fundamentally unobservable nonlinear dynamics to the readily observable pattern dynamics. We also show that the space-time patterns produced by the simulations lead to a scale-invariant hierarchy of patterns, similar to other nonlinear systems. We point out that a similar program of simulations has been very successful in weather forecasting, in which current and past observations of weather patterns are routinely extrapolated forward in time via numerical simulations in order to forecast future weather patterns.

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Tesis sobre el tema "Multi-Scale nonlinear dynamics"

Nishimura, Seiya. "Study on multi-scale nonlinear dynamics of magnetic islands in tokamak plasmas". Aix-Marseille 1, 2009. http://www.theses.fr/2009AIX11060.

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Cette thèse est consacrée à la modélisation et à la simulation de la dynamique non linéaire d’un îlot magnétique en présence d’un gradient de pression dans un plasma magnétisé de tokamak. Ce mode nommé ‘’drift tearing’’ est en fait un mode de déchirement couplé à une onde de dérive électronique. Les instabilités de déchirement jouent un rôle important dans la stabilité magnétohydrodynamique des plasmas de fusion thermonucléaire. Il est en effet admis que ces instabilités détermineront la limite en pression dans les plasmas du futur tokamak ITER. Il se trouve que de nombreuses questions restent ouvertes concernant les conditions d'apparition ainsi que la dynamique de ces modes en régime non-linéaire. Un point très important est la vitesse de rotation de l'îlot magnétique qui se développe lors de l'apparition d'une instabilité de déchirement. Cette vitesse de rotation, en particulier son signe, conditionne l'évolution non linéaire de l'îlot. Dans cette thèse, les mécanismes physiques sous-jacents à cette rotation sont explorés. Un résultat important est que le sens de la rotation de l'îlot change en fonction de la viscosité et de la résistivité. Afin de comprendre ce phénomène, un modèle analytique a été développé et a permis de comparer favorablement les prédictions théoriques aux simulations numériques de la dynamique de l'îlot en régime non-linéaire. Ce modèle a aussi permis de démontrer un résultat d'application pratique : l'augmentation de la fréquence de rotation avec le nombre de Prandtl magnétique
This thesis is devoted to the modelling and simulation of the nonlinear dynamics of a magnetic island in presence of a pressure gradient in a tokamak plasma. This mode called “drift tearing” is in fact a tearing mode coupled to an electronic drift wave. Tearing instabilities play an important role in the magneto-hydrodynamic stability of thermonuclear fusion plasmas. It is admitted that these instabilities will determine the pressure limit in future plasma tokamak reactors like ITER. There are still many open questions related to the conditions of appearance as well as the nonlinear dynamics of these modes. An important issue is the island rotation which develops during a tearing instability. Indeed, the rotation speed as well as its sign have an important impact on the nonlinear evolution of the magnetic island. In this thesis the physical mechanisms underlying this rotation are explored. An important result is that the rotation direction of the island depends on the viscosity and the resistivity parameters. To understand this phenomenon, a model is developed and validated by numerical simulations. A practical result is derived from this model: the rotation frequency of the magnetic island increases with the magnetic Prandtl number

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Lu, Xiaoxin. "Modélisation électro-mécanique multi-échelle des nanocomposites graphène/polymère". Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLC058/document.

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Cette étude porte sur le développement de modèles et de méthodes numériques pour prédire les propriétés électriques et mécaniques des nanocomposites polymères/graphènes.Dans une première partie, un modèle nonlinéaire de conduction électrique prenant en compte l’effet tunnel est introduit pour déterminer la conductivité effective de ces nanocomposites au travers d’une procédure d’homogénéisation numérique. Celle-ci, basée sur une formulation éléments finis a mis en évidence l’influence des paramètres microstructuraux sur la conductivité effective au travers d’une étude statistique.Ensuite, un modèle atomistique de l’interface polymère/graphène a été proposé pour valuer les propriétés de l'interface et de l'interphase. Les champs de contrainte et de déplacement ont été identifiés par une extension de la procédure d'Hardy-Murdoch à partir des simulations de mécanique moléculaire. À l'aide de ces champs, un modèle élastique continue avec des interfaces imparfaites a été identifié et comparé aux résultats des simulations de mécanique moléculaire. Finalement, le modèle atomistique a permis d’identifier un modèle de zone cohésive nonlinéaire pour modéliser la décohésion à l’interface polymère/graphène. Une procédure d’homogénéisation numérique par la méthode des éléments finis a été introduite pour estimer les propriétés mécaniques effectives dans le cadre des transformations finies. Les microstructures déformées ont été utilisées dans le modèle électrocinétique pour déterminer l’impact de la décohésion interfaciale sur la conductivité effective
This work contributes to developing numerical methodologies for predicting the electrical and mechanical properties of graphene/polymer nanocomposites, which can provide a better view for the design of new materials.First, a nonlinear electrical conduction model taking into account the tunneling effect is introduced to determine the effective conductivity of the graphene/polymer nanocomposites through a numerical homogenization procedure. The influences of barrier height and microstructural parameters on the conductivity were demonstrated.Then, to characterize the properties of interphases and interfaces, we employed the Murdoch-Hardy procedure combined with the molecular dynamics method to study the mechanical properties of the graphene/polymer nanocomposites. The stiffness tensor components of the interphase, interface andnbulk polymer region are identified. Based on these fields, a continuous elastic model with imperfect interface has been identified and compared with the results of molecular dynamics simulations.Finally, the atomistic model was used to identify a nonlinear cohesive zone model to simulate the decohesion at the interface of polymer and graphene. A numerical homogenization procedure by finite element method was introduced to estimate the effective mechanical properties in the framework of the finite strains. The proposed mechanical modeling is finally extended to the finite strain problem to predict the evolution of percolation threshold under tension within the proposed electrical model

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Alsassa, Salma. "Two-dimentional complex modeling of bone and joint infections using agent-based simulation". Thesis, Brest, 2019. http://www.theses.fr/2019BRES0022.

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Le diagnostic et la prise en charge des infections ostéo-articulaires (IOA) sont souvent complexes occasionnant une perte osseuse irréversible. La variabilité intra et inter-patient en terme de présentation clinique rend impossible le recours à une description systématique ou à une analyse statistique pour le diagnostic et l'étude de cette pathologie. Le développement d'IOA résulte d'interactions complexes entre les mécanismes cellulaires et moléculaires du tissu osseux et les bactéries. L'objectif de cette thèse est de modéliser l'IOA afin de simuler le comportement du système suite à des interactions au niveau cellulaire et moléculaire en utilisant l'approche de modélisation à base d'agents. Nous avons utilisé une méthode basée sur l'analyse bibliographique pour extraire les caractéristiques du modèle et les utiliser pour deux aspects. Le premier consiste en l'élaboration de la structure du modèle en identifiant les agents et les interactions, et le deuxième concerne l'estimation quantitative des différents paramètres du modèle. La réponse du système BJI aux différentes tailles d’inoculum bactérien a été simulée par la variation de différents paramètres. L'évolution des agents simulés a ensuite été analysée en utilisant une modélisant par des systèmes dynamiques non linéaires et une méthodologie "Datadriven", grâce auxquelles nous avons décrit le système d'IOA et identifié des relations plausibles entre les agents. Le modèle a réussi à présenter la dynamique des bactéries, des cellules immunitaires innées et des cellules osseuses au cours de la première étape de l'IOA et pour différentes tailles d'inoculum bactérien. La simulation a mis en évidence les conséquences sur le tissu osseux résultant du processus de remodelage osseux au cours de l'IOA. Ces résultats peuvent être considérés comme une base pour une analyse plus approfondie et pour la proposition de différentes hypothèses et scénarios de simulation qui pourraient être étudiés dans ce laboratoire virtuel
Bone and joint infections are one of the most challenging bone pathologies that associated with irreversible bone loss and long costly treatment. The high intra and inter patient's variability in terms of clinical presentation makes it impossible to rely on the systematic description or classical statistical analysis for its diagnosis or studying. The development of BJI encompasses a complex interplay between the cellular and molecular mechanisms of the host bone tissue and the infecting bacteria. The objective of this thesis is to provide a novel computational modeling framework that simulates the behavior resulting from the interactions on the cellular and molecular levels to explore the BJI dynamics qualitatively and comprehensively, using an agent-based modeling approach. We relied on a meta-analysis-like method to extract the quantitative and qualitative data from the literature and used it for two aspects. First, elaborating the structure of the model by identifying the agents and the interactions, and second estimating quantitatively the different parameters of the model. The BJI system’s response to different microbial inoculum sizes was simulated with respect to the variation of several critical parameters. The simulation output data was then analyzed using a data-driven methodology and system dynamics approach, through which we summarized the BJI complex system and identified plausible relationships between the agents using differential equations. The BJI model succeeded in imitating the dynamics of bacteria, the innate immune cells, and the bone cells during the first stage of BJI and for different inoculum size in a compatible way. The simulation displayed the damage in bone tissue as a result of the variation in bone remodeling process during BJI. These findings can be considered as a foundation for further analysis and for the proposition of different hypotheses and simulation scenarios that could be investigated through this BJI model as a virtual lab

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Singla, Puneet. "Multi-resolution methods for high fidelity modeling and control allocation in large-scale dynamical systems". Texas A&M University, 2005. http://hdl.handle.net/1969.1/3785.

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This dissertation introduces novel methods for solving highly challenging model- ing and control problems, motivated by advanced aerospace systems. Adaptable, ro- bust and computationally effcient, multi-resolution approximation algorithms based on Radial Basis Function Network and Global-Local Orthogonal Mapping approaches are developed to address various problems associated with the design of large scale dynamical systems. The main feature of the Radial Basis Function Network approach is the unique direction dependent scaling and rotation of the radial basis function via a novel Directed Connectivity Graph approach. The learning of shaping and rota- tion parameters for the Radial Basis Functions led to a broadly useful approximation approach that leads to global approximations capable of good local approximation for many moderate dimensioned applications. However, even with these refinements, many applications with many high frequency local input/output variations and a high dimensional input space remain a challenge and motivate us to investigate an entirely new approach. The Global-Local Orthogonal Mapping method is based upon a novel averaging process that allows construction of a piecewise continuous global family of local least-squares approximations, while retaining the freedom to vary in a general way the resolution (e.g., degrees of freedom) of the local approximations. These approximation methodologies are compatible with a wide variety of disciplines such as continuous function approximation, dynamic system modeling, nonlinear sig-nal processing and time series prediction. Further, related methods are developed for the modeling of dynamical systems nominally described by nonlinear differential equations and to solve for static and dynamic response of Distributed Parameter Sys- tems in an effcient manner. Finally, a hierarchical control allocation algorithm is presented to solve the control allocation problem for highly over-actuated systems that might arise with the development of embedded systems. The control allocation algorithm makes use of the concept of distribution functions to keep in check the "curse of dimensionality". The studies in the dissertation focus on demonstrating, through analysis, simulation, and design, the applicability and feasibility of these ap- proximation algorithms to a variety of examples. The results from these studies are of direct utility in addressing the "curse of dimensionality" and frequent redundancy of neural network approximation.

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Kim, Hee Sun. "Nonlinear multi-scale anisotropic material and structural models for prosthetic and native aortic heart valves". Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/29671.

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Thesis (Ph.D)--Civil and Environmental Engineering, Georgia Institute of Technology, 2009.
Committee Chair: Haj-Ali, Rami; Committee Member: White, Donald; Committee Member: Will, Kenneth; Committee Member: Yavari, Arash; Committee Member: Yoganathan, Ajit. Part of the SMARTech Electronic Thesis and Dissertation Collection.

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Vallet, Anais. "Etude de la balance Excitatiοn/Ιnhibitiοn de régiοns cérébrales impliquées dans une tâche de cοntrôle inhibiteur : mοdélisatiοn de dοnnées οbtenues en Ιmagerie par Résοnance Μagnétique fοnctiοnnelle et inversiοn". Electronic Thesis or Diss., Normandie, 2024. http://www.theses.fr/2024NORMC014.

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En psychologie, le contrôle inhibiteur est un mécanisme cognitif qui permet de stopper une ré-ponse motrice, émotionnelle ou cognitive non adaptée pour la réalisation d’un but désiré. Au niveaucérébral, le contrôle inhibiteur est associé au fonctionnement en réseau de régions cérébrales, quipeut être mesuré à partir du signal BOLD en IRMf. Des régions de contrôle préfrontales abaissentl’activité BOLD de régions cibles. L’IRMf permet de mesurer de manière indirecte l’activité desneurones. Comment peut-on alors inférer à partir de données d’IRMf des propriétés excitatriceset inhibitrices (E/I) neurales au sein de régions cérébrales impliquées dans une tâche de contrôleinhibiteur ?Nous partons d’un modèle biophysique non linéaire, hiérarchique qui décrit les évolutions tempo-relles des activités neurales excitatrice et inhibitrice par région (Naskar et al., 2021). Ces varia-tions d’activité produisent des changements BOLD dans chaque région cérébrale. L’analyse de cemodèle nous permet de : 1) identifier des paramètres neuraux de la balance E/I ; 2) montrer quel’augmentation d’activité BOLD d’une région de contrôle ne permet pas d’abaisser l’activité BOLDd’une région cible parce que les régions sont connectées par leurs neurones excitateurs uniquement ;3) proposer une nouvelle architecture de connectivité pour le permettre ; 4) étudier comment labaisse d’activité de la région cible dépend de la balance E/I dans la cible. Nous proposons alorsune nouvelle procédure d’inversion. Nous en vérifions la fiabilité avec des simulations, avant deprésenter une preuve de concept sur les données d’un sujet pendant une tâche de Think/NoThink,un paradigme d’étude du contrôle inhibiteur des intrusions mnésiques (Mary et al., 2020)
In psychology, inhibitory control is a cognitive mechanism that stops a motor, emotional orcognitive response from achieving a desired goal. At cerebral level, inhibitory control is associatedwith a network of brain regions, whose function may be measured using BOLD signals from fMRI.Prefrontal control regions lower the BOLD activity of target regions. fMRI provides an indirectmeasure of the activity of neurons. How can we then infer from fMRI data, neural excitatory andinhibitory (E/I) properties of brain regions involved in an inhibitory control task ?We start with a non-linear biophysical model that describes by region the temporal evolutionof neural excitatory and inhibitory activities (Naskar et al., 2021). These variations in activityproduce BOLD changes in each brain region. Analysis of this model enables us to : 1) identifyneural parameters of the E/I balance ; 2) show that increasing the BOLD activity of a controlregion does not lower the BOLD activity of a target region, since these regions are connected bytheir excitatory neurons only ; 3) propose a new connectivity architecture to enable this ; 4) studyhow the lowering of activity in the target region depends on the E/I balance in the target region.We then propose a new inversion procedure. We check its reliability through simulations, beforepresenting a proof-of-concept using real data from a subject during a Think/No-Think task, aparadigm used for studying the inhibitory control of memory intrusions (Mary et al., 2020)

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Montegiglio, Pasquale. "Nonlinear Circuit Models for EH Applications Including Multiple Scales". Doctoral thesis, 2019. http://hdl.handle.net/11589/161060.

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Il presente lavoro di tesi è incentrato sulla modellazione dinamica dei dispositivi per l’energy harvesting basati su materiali piezoelettrici. L’indagine mira allo studio ed alla riproduzione dei comportamenti non lineari ascrivibili a due differenti cause: non linearità costitutive del materiale elettroattivo; non linearità legate ad effetti geometrici. Gli approcci adottati perfezionano i classici modelli di ordine ridotto attraverso l’inclusione di effetti dovuti sia all’isteresi ferroelettrica/ferroelastica dei materiali piezoelettrici sia alle grandi deformazioni, pervenendo, in ultimo, a sintetiche ed efficaci rappresentazioni circuitali in grado di fornire un’interpretazione intuitiva dei processi di trasduzione energetica in atto. Le due differenti cause di non linearità vengono esaminate separatamente. La riproduzione delle dinamiche non lineari dei domini di un cristallo di PZT è affidata ad un modello basato sulla fisica. L’adozione di tale approccio permette di esplorare le possibilità di miglioramento delle performance dei dispositivi basati su materiali piezoceramici, attraverso un’opportuna ingegnerizzazione del materiale. In merito alla seconda causa di non linearità, viene adottata una strategia computazionale ibrida, finalizzata a riprodurre gli effetti delle non linearità geometriche sulla dinamica di dispositivi flessibili in PVDF sottoposti a grandi deformazioni. La procedura proposta, validata sperimentalmente, dimostra di ridurre in modo significativo l’onere computazionale necessario allo sviluppo di analisi dinamiche non lineari multiscala, preservando un livello di accuratezza più che soddisfacente.
This thesis focuses on modeling the dynamic behavior of piezoelectric energy harvester devices. Nonlinearities arising from different aspects, such as material and geometrical effects, are taken into account. Classical reduced-order modeling approaches have been enhanced by including effects of ferroelastic and ferroelectric hysteresis and large deformations, yielding to effective circuit representations that allow for an intuitive insight in the energy transduction processes characterizing the considered class of devices. Nonlinearity sources have been assessed in a separate way. A physics-based model has been employed in order to reproduce hysteretic dynamics of PZT crystal domains. This provides an insight on how, through an engineered crystal design, material nonlinearities can be exploited in order to improve generation performances of piezoceramic-based harvesters. Moreover, an effective hybrid compu- tational framework is proposed for modeling geometric nonlinear effects on the response of flexible PVDF-based harvesters under large deformations. The procedure, experimentally validated, significantly reduce the computational effort for nonlinear dynamic multiscale analysis, while preserving a satisfactory accuracy.

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Libros sobre el tema "Multi-Scale nonlinear dynamics"

Zeitlin, Vladimir. Geophysical Fluid Dynamics. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198804338.001.0001.

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The book explains the key notions and fundamental processes in the dynamics of the fluid envelopes of the Earth (transposable to other planets), and methods of their analysis, from the unifying viewpoint of rotating shallow-water model (RSW). The model, in its one- or two-layer versions, plays a distinguished role in geophysical fluid dynamics, having been used for around a century for conceptual understanding of various phenomena, for elaboration of approaches and methods, to be applied later in more complete models, for development and testing of numerical codes and schemes of data assimilations, and many other purposes. Principles of modelling of large-scale atmospheric and oceanic flows, and corresponding approximations, are explained and it is shown how single- and multi-layer versions of RSW arise from the primitive equations by vertical averaging, and how further time-averaging produces celebrated quasi-geostrophic reductions of the model. Key concepts of geophysical fluid dynamics are exposed and interpreted in RSW terms, and fundamentals of vortex and wave dynamics are explained in Part 1 of the book, which is supplied with exercises and can be used as a textbook. Solutions of the problems are available at Editorial Office by request. In-depth treatment of dynamical processes, with special accent on the primordial process of geostrophic adjustment, on instabilities in geophysical flows, vortex and wave turbulence and on nonlinear wave interactions follows in Part 2. Recently arisen new approaches in, and applications of RSW, including moist-convective processes constitute Part 3.

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Zeitlin, Vladimir. Resonant Wave Interactions and Resonant Excitation of Wave-guide Modes. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198804338.003.0012.

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The idea of resonant nonlinear interactions of waves, and of resonant wave triads, is first explained using the example of Rossby waves, and then used to highlight a mechanism of excitation of wave-guide modes, by impinging free waves at the oceanic shelf, and at the equator. Physics and mathematics of the mechanism, which is related to the phenomena of parametric resonance and wave modulation, are explained in detail in both cases. The resulting modulation equations, of Ginzburg–Landau or nonlinear Schrodinger type, are obtained by multi-scale asymptotic expansions and elimination of resonances, after the explanation of this technique. The chapter thus makes a link between geophysical fluid dynamics and other branches of nonlinear physics. A variety of nonlinear phenomena including coherent structure formation is displayed. The resonant excitation of wave-guide modes provides an efficient mechanism of energy transfer to the wave guides from the large to the small.

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Capítulos de libros sobre el tema "Multi-Scale nonlinear dynamics"

Cui, Dongze, Mohamed Ichchou, Abdel-Malek Zine y Noureddine Atalla. "Multi-scale Dynamics and Nonlinear Eigenvalue Problem of Heterogeneous Metastructures Using a Wave Finite Element Scheme and Modal Strain Energy Method". En Advances in Nonlinear Dynamics and Control of Mechanical and Physical Systems, 141–52. Singapore: Springer Nature Singapore, 2024. http://dx.doi.org/10.1007/978-981-99-7958-5_11.

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Yang, Huiyi, Dongwu Li y Chao Xu. "A Novel Tangential Friction Modelling Approach Considering Multi-scale Contact Pressure Distribution for Predicting the Nonlinear Dynamics of a Bolted Joint". En Lecture Notes in Mechanical Engineering, 3675–88. Singapore: Springer Nature Singapore, 2024. http://dx.doi.org/10.1007/978-981-99-8048-2_256.

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Popel, Sergey I. "Fine Particles and Nonlinear Processes in Plasma Heliogeophysics". En Multi-scale Dynamical Processes in Space and Astrophysical Plasmas, 197–208. Berlin, Heidelberg: Springer Berlin Heidelberg, 2012. http://dx.doi.org/10.1007/978-3-642-30442-2_22.

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Browning, Philippa K., Michael R. Bareford y Mykola Gordovskyy. "Relaxation and Heating Triggered by Nonlinear Kink Instability: Application to Solar Flares and Coronal Heating". En Multi-scale Dynamical Processes in Space and Astrophysical Plasmas, 69–75. Berlin, Heidelberg: Springer Berlin Heidelberg, 2012. http://dx.doi.org/10.1007/978-3-642-30442-2_8.

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Actas de conferencias sobre el tema "Multi-Scale nonlinear dynamics"

Littell, Justin, Michael Seal, Edwin Fasanella, Karen Jackson y Martin Annett. "The Development of Two Composite Energy Absorbers for Use in a Transport Rotorcraft Airframe Crash Testbed (TRACT 2) Full-Scale Crash Test". En Vertical Flight Society 71st Annual Forum & Technology Display, 1–18. The Vertical Flight Society, 2015. http://dx.doi.org/10.4050/f-0071-2015-10141.

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Two composite energy absorbers were developed and evaluated at NASA Langley Research Center through multi-level testing and simulation performed under the Transport Rotorcraft Airframe Crash Testbed (TRACT) research program. A conical-shaped energy absorber, designated the conusoid, was evaluated that consisted of four layers of hybrid carbon-Kevlar® plain weave fabric oriented at [+45°°/-45°/-45°/+45°] with respect to the vertical direction. A sinusoidal-shaped energy absorber, designated the sinusoid, was developed that consisted of hybrid carbon-Kevlar® plain weave fabric face sheets, two layers for each face sheet oriented at ±45° with respect to the vertical direction, and a closed-cell ELFOAM® P200 polyisocyanurate (2.0-lb/ft3) foam core. The design goal for the energy absorbers was to achieve average floor-level accelerations of between 25- and 40-g during the full-scale crash test of a retrofitted CH-46E helicopter airframe, designated TRACT 2. Variations in both designs were assessed through dynamic crush testing of component specimens. Once the designs were finalized, subfloor beams of each configuration were fabricated and retrofitted into a barrel section of a CH-46E helicopter. A vertical drop test of the barrel section was conducted onto concrete to evaluate the performance of the energy absorbers prior to retrofit into TRACT 2. The retrofitted airframe was crash tested under combined forward and vertical velocity conditions onto soft soil. Finite element models were developed of all test articles and simulations were performed using LS-DYNA®, a commercial nonlinear explicit transient dynamic finite element code. Test-analysis results are presented for each energy absorber as comparisons of time-history responses, as well as predicted and experimental structural deformations and progressive damage under impact loading for each evaluation level.

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JI, JUNYI, Derek Gloudemans, Gergely Zachár, William Barbour, Jonathan Sprinkle, Benedetto Piccoli y Daniel Work. "Poster: Multi-scale dynamics of nonlinear traffic waves". En 77th Annual Meeting of the APS Division of Fluid Dynamics. American Physical Society, 2024. http://dx.doi.org/10.1103/aps.dfd.2024.gfm.p2685652.

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Hramov, Alexander E., Vladimir Makarov, Daniil Kirsanov, Mikhail Goremyko y Andrej Andreev. "Nonlinear dynamics of the complex multi-scale network". En Saratov Fall Meeting 2017: Fifth International Symposium on Optics and Biophotonics: Laser Physics and Photonics XIX; Computational Biophysics and Analysis of Biomedical Data IV, editado por Vladimir L. Derbov y Dmitry E. Postnov. SPIE, 2018. http://dx.doi.org/10.1117/12.2315095.

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Montegiglio, Pasquale, Claudio Maruccio, Giuseppe Acciani, Gianluca Rizzello y Stefan Seelecke. "Nonlinear Multi-Scale Dynamics Modeling of a Piezoelectric Energy Harvester". En 2018 IEEE International Conference on Environment and Electrical Engineering and 2018 IEEE Industrial and Commercial Power Systems Europe (EEEIC / I&CPS Europe). IEEE, 2018. http://dx.doi.org/10.1109/eeeic.2018.8493962.

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Sepehri, A. y K. Farhang. "A Multi-Scale Account of Friction-Vibration Interaction". En STLE/ASME 2008 International Joint Tribology Conference. ASMEDC, 2008. http://dx.doi.org/10.1115/ijtc2008-71256.

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Using a nonlinear model of a two disk brake system, coupled equations of motion are found for their frictional interaction. The mathematical formulation relates the tribological events at micron scale and the macroscopic scale vibration response of a two-disk brake system. This is accomplished by a viscoelastic account of interaction at the micron scale, its statistical quantification through the approximate analytical representation of the statistical expectation of contact force and the introduction of the contact force into the macro-scale dynamics of the two-disk system. Steady-state analysis of the system establishes the relation between friction torque and speed and supports observed behavior of many mechanical systems with friction. It is shown that, as a result of coupling of the macro-system’s dynamics and contact, there are combinations of parameters at the micro- and macro-scale that yield negative slope in friction torque/sliding speed relation, a well known source of dynamic instability. This results in an effective negative damping that tends to decrease with decrease in the normal load and/or increase in structural damping of the system.

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Roy, Samit, Avinash Akepati y Nicholas Hayes. "Multi-scale Modeling of Nano-Particle Reinforced Polymers in the Nonlinear Regime". En 53rd AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference
20th AIAA/ASME/AHS Adaptive Structures Conference
14th AIAA. Reston, Virigina: American Institute of Aeronautics and Astronautics, 2012. http://dx.doi.org/10.2514/6.2012-1822.

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Weiss, M., S. Ture y C.-H. Lamarque. "MULTI-SCALE ENERGY PUMPING BETWEEN A MAIN OSCILLATOR INCLUDING SAINT-VENANT TERM AND A NONLINEAR ENERGY SINK". En 4th International Conference on Computational Methods in Structural Dynamics and Earthquake Engineering. Athens: Institute of Structural Analysis and Antiseismic Research School of Civil Engineering National Technical University of Athens (NTUA) Greece, 2014. http://dx.doi.org/10.7712/120113.4634.c1121.

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Williams, Todd. "A New Type of General Theory for the Development of Nonlinear, Multi-scale Plate Theories". En 49th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference
16th AIAA/ASME/AHS Adaptive Structures Conference
10t. Reston, Virigina: American Institute of Aeronautics and Astronautics, 2008. http://dx.doi.org/10.2514/6.2008-2305.

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Shukla, Amit. "Classification of Nonlinear Dynamics of Human Posture Using Support Vector Machines". En 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/detc2013-13609.

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Human postural control can be modeled as a complex, non-linear multi-sensory and multi actuation system. Postural control requires a balance between various sensory inputs and the corresponding response in a motor control framework. Various motor control disorders result in a propensity for fall. In this paper, a classification scheme using support vector machines (SVM) is investigated to classify individuals between healthy and those prone to balance disorders including falls. First, a computational model is described to illustrate the proposed approach. It is shown that using SVM, in conjunction with L2 Norm associated with the phase space trajectories, it is possible to classify fallers and non-fallers. This metric can then be utilized for clinical application upon further evaluation. This may benefit clinical evaluation of Parkinson’s subjects by complementing the widely used UPDRS scale.

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Heinze, Torsten, Lars Panning-von Scheidt, Jörg Wallaschek y Andreas Hartung. "Rotational Speed-Dependent Contact Formulation for Nonlinear Blade Dynamics Prediction". En ASME Turbo Expo 2018: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/gt2018-75290.

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Considering rotational speed-dependent stiffness for vibrational analysis of friction-damped bladed disk models has proven to lead to significant improvements in nonlinear frequency response curve computations. The accuracy of the result is driven by a suitable choice of reduction bases. Multi-model reduction combines various bases which are valid for different parameter values. This composition reduces the solution error drastically. The resulting set of equations is typically solved by means of the harmonic balance method. Nonlinear forces are regularized by a Lagrangian approach embedded in an alternating frequency/time domain method providing the Fourier coefficients for the frequency domain solution. The aim of this paper is to expand the multi-model approach to address rotational speed-dependent contact situations. Various reduction bases derived from composing Craig-Bampton, Rubin-Martinez, and hybrid interface methods will be investigated with respect to their applicability to capture the changing contact situation correctly. The methods validity is examined based on small academic examples as well as large-scale industrial blade models. Coherent results show that the multi-model composition works successfully, even if multiple different reduction bases are used per sample point of variable rotational speed. This is an important issue in case that a contact situation for a specific value of the speed is uncertain forcing the algorithm to automatically choose a suitable basis. Additionally, the randomized singular value decomposition is applied to rapidly extract an appropriate multi-model basis. This approach improves the computational performance by orders of magnitude compared to the standard singular value decomposition, while preserving the ability to provide a best rank approximation.

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Informes sobre el tema "Multi-Scale nonlinear dynamics"

RESEARCH ON DYNAMIC LOAD CARRYING CAPACITY OF ASSEMBLED INTERNAL STIFFENING WIND TURBINE TOWER BASED ON MULTI-SCALE MODELING. The Hong Kong Institute of Steel Construction, agosto de 2022. http://dx.doi.org/10.18057/icass2020.p.513.

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"The development of wind power technology requires higher and larger wind turbines, which requires the bearing tower to increase its height and diameter. The assembled internal stiffened wind turbine tower divides the tower into multiple arc plates along the longitudinal direction, which can be easy transported to the site for assembly. That can solve the problem of height limit in highway transportation. At the same time, the internal stiffener provides better stability and can replace the bottom tower section of conventional wind turbine tower. In this study, the tower section of assembled internal stiffened wind turbine is modeled, and the longitudinal segmented tower section is assembled to the actual full-scale tower section model for nonlinear dynamic analysis. The influence of weld is considered by multi-scale modeling, combined with the plastic damage theory of steel materials. The whole collapse process of tower wall instability and deformation failure of wind turbine tower under the extreme wind condition is simulated, and the influence of various parameters of tower section on its bearing capacity is analysed. The damage position and damage development during tower collapse are predicted by using plastic damage theory, so as to provide reference for the design of assembled internally stiffened wind turbine tower."

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RESEARCH ON DYNAMIC LOAD CARRYING CAPACITY OF ASSEMBLED INTERNAL STIFFENING WIND TURBINE TOWER BASED ON MULTI-SCALE MODELING. The Hong Kong Institute of Steel Construction, marzo de 2023. http://dx.doi.org/10.18057/ijasc.2023.19.1.11.

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The development of wind power technology requires higher and larger wind turbines, which requires the bearing tower to increase its height and diameter. The assembled internal stiffened wind turbine tower divides the tower into multiple arc plates along the longitudinal direction, which can be easy transported to the site for assembly. That can solve the problem of height limit in highway transportation. At the same time, the internal stiffener provides better stability and can replace the bottom tower section of conventional wind turbine tower. In this study, the tower section of assembled internal stiffened wind turbine is modeled, and the longitudinal segmented tower section is assembled to the actual full-scale tower section model for nonlinear dynamic analysis. The influence of weld is considered by multi-scale modeling, combined with the plastic damage theory of steel materials. The whole collapse process of tower wall instability and deformation failure of wind turbine tower under the extreme wind condition is simulated, and the influence of various parameters of tower section on its bearing capacity is analysed. The damage position and damage development during tower collapse are predicted by using plastic damage theory, so as to provide reference for the design of assembled internally stiffened wind turbine tower.

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