Segui questo link per vedere altri tipi di pubblicazioni sul tema: Couple dynamic.
Tesi sul tema "Couple dynamic"
Cita una fonte nei formati APA, MLA, Chicago, Harvard e in molti altri stili
Vedi i top-50 saggi (tesi di laurea o di dottorato) per l'attività di ricerca sul tema "Couple dynamic".
Accanto a ogni fonte nell'elenco di riferimenti c'è un pulsante "Aggiungi alla bibliografia". Premilo e genereremo automaticamente la citazione bibliografica dell'opera scelta nello stile citazionale di cui hai bisogno: APA, MLA, Harvard, Chicago, Vancouver ecc.
Puoi anche scaricare il testo completo della pubblicazione scientifica nel formato .pdf e leggere online l'abstract (il sommario) dell'opera se è presente nei metadati.
Vedi le tesi di molte aree scientifiche e compila una bibliografia corretta.
1
Manceau, Charlotte. "Analyse des dynamiques et processus dyadiques sous-jacents à l'expérience du couple confronté à une maladie neuroévolutive". Electronic Thesis or Diss., Université de Lille (2022-....), 2024. https://pepite-depot.univ-lille.fr/ToutIDP/EDSHS/2024/2024ULILH020.pdf.
Testo completoAbstract (sommario):
Les maladies neuroévolutives (MNE) soulèvent de nombreuses implications pour la santé, le bien-être et la qualité de vie des personnes malades et de leur conjoint·e. Face à ces défis, de nombreuses études ont cherché à comprendre le vécu de ces personnes et à évaluer l'efficacité d'interventions centrées sur le bien-être. Si ces approches individuelles sont importantes, la littérature a souligné l'importance de considérer la dyade et les processus relationnels en jeu, notamment pour optimiser ces accompagnements. Or, si de nombreux modèles détaillent la façon dont le couple peut s'ajuster à une maladie chronique, hormis quelques exceptions, les MNE n'y sont pas intégrées. Cela soulève le besoin de s'intéresser davantage au fonctionnement du couple dans le cadre des MNE. Ces travaux de thèse avaient donc pour objectifs de mieux comprendre le vécu des couples et les processus dyadiques sous-jacents à leur fonctionnement, en réalisant tout d'abord une méta-synthèse centrée sur diverses MNE (étude 1), puis deux études centrées sur la maladie de Parkinson (MP) (études 2 et 3). Saisir les changements dans le fonctionnement du couple à travers différents temps de la maladie était un autre objectif. Une synthèse thématique (étude 1) et deux études empiriques qualitatives utilisant une Analyse Interprétative Phénoménologique (étude 2 et 3) ont été réalisées. L'étude 2 explorait le vécu de 15 couples au stade spécifique dit de lune de miel de la MP. L'étude 3 consistait en une mise en parallèle des processus identifiés dans trois échantillons distincts de 15 couples, à trois temps de la MP, afin d'identifier les patterns de fonctionnement prévalents et les transitions dans la dynamique des couples au fil de l'évolution de la maladie. Les études 2 et 3 ont identifié cinq patterns de fonctionnement dyadique, ainsi que des transitions dans la dynamique conjugale, souvent liées à l'évolution des symptômes. Certains partenaires font preuve de soutien mutuel et de réinterprétation positive de leur expérience, ce fonctionnement évoluant vers une dynamique où l'aidant·e apporte une aide subtile pour tenter de préserver cet équilibre. Pour d'autres, cette aide discrète, d'emblée source de négociations au sein du couple, se transforme brutalement en contrôle. Alors que certains conjoint·e·s luttent contre la maladie dès les premiers stades, en exerçant une forme de contrôle, leur partenaire se désengage. Avec l'évolution des symptômes, il n'est plus possible d'éviter ce contrôle qui se transforme en intrusion. De plus, d'autres couples adoptent une hyperprotection rigide face à la détresse induite par la MP, cet évitement se renforçant avec le temps. Enfin, un autre pattern, caractérisé par une difficulté à comprendre la perspective de l'autre et un désengagement mutuel des partenaires, se rigidifie également avec l'évolution de la MP, ce fonctionnement pouvant aboutir à une remise en question de la relation de couple. Ces études ont mis en évidence différentes dynamiques conjugales et plusieurs processus associés dans le cadre des MNE et plus précisément la MP. Les transitions identifiées dans le fonctionnement du couple au fil de l'évolution de la maladie montrent qu'il est important de considérer le vécu du couple dès le début de la maladie et durant son entièreté. Ces travaux sont importants puisqu'ils suggèrent plusieurs types du fonctionnement dyadique face aux MNE. De plus, ils relèvent des similitudes dans les processus observés dans le cadre de la MP, de la maladie d'Alzheimer ou d'autres maladies chroniques. Ces différents aspects sont donc importants pour la création d'interventions transdiagnostiques et de futures recherches visant à explorer les processus dyadiques associés au vécu du couple face à d'autres maladies moins étudiéesNeurodegenerative diseases (NDDs) raise numerous implications for the health, well-being, and quality of life of both the partner with the disease and their caregiving spouses. In the face of these challenges, numerous studies have sought to understand the experiences of these individuals and evaluate the effectiveness of well-being-centered interventions. While individual approaches are important, the literature has underscored the significance of considering the dyad and the relational processes at play, particularly to optimize such interventions. However, while numerous models detail how couples adjust to chronic illness, NDDs are not integrated into these models, except for a few exceptions, indicating the need for further investigation of couple functioning in the context of NDDs. Therefore, the objectives of this thesis were to better understand the experiences of couples and the dyadic processes underlying their functioning, through a meta-synthesis centered on various NDDs (study 1) and two studies and functioning of couples facing Parkinson's disease (PD) (studies 2 and 3). Capturing changes in couple functioning across different stages of the disease was another objective. A thematic synthesis (study 1) and two qualitative empirical studies using Interpretative Phenomenological Analysis (study 2) were conducted. Study 2 explored the experiences of 15 couples at the specific stage known as the honeymoon period of PD. Study 3 involved a comparison of processes identified in three distinct samples of 15 couples, at three stages of PD, to identify prevalent functioning patterns and transitions in couple dynamics throughout the disease progression. Studies 2 and 3 identified five patterns of dyadic functioning, as well as transitions in dyadic dynamics, often linked to symptom progression. Some partners demonstrate mutual support and positive reinterpretation of their experience, evolving towards a dynamic where the caregiver provides subtle assistance to preserve this balance. For others, this discreet help, a subject of negotiation within the couple from the onset of the disease, abruptly transforms into control. While some spouses struggle against the disease from the early stages by exerting a form of control, their partner disengages. With symptom progression, it becomes impossible to avoid this control, which turns into intrusion. Additionally, some couples adopt a rigid hyperprotection against the distress induced by PD, with this avoidance strengthening over time. Finally, another pattern, characterized by difficulty in understanding the other's perspective and by a mutual disengagement shown by partners, also becomes more rigid over time, potentially leading to questioning the couple's relationship. These studies have highlighted different dyadic dynamics and their associated processes within the context of NDDs, specifically PD. The transitions identified in couple functioning throughout the disease progression indicate the importance of considering the couple's experience from the onset of the disease and throughout its evolution. These findings are significant, as they suggest several specificities of dyadic functioning in the face of NDDs. Furthermore, they reveal similarities in processes observed in the context of PD, Alzheimer's disease, or other chronic illnesses. These various aspects are thus important for the development of transdiagnostic interventions and future research aimed at exploring dyadic processes associated with couples' experience of other less studied diseases
2
Meguenani, Anis. "Safe control of robotic manipulators in dynamic contexts". Thesis, Paris 6, 2017. http://www.theses.fr/2017PA066420/document.
Testo completoAbstract (sommario):
L'objectif de cette thèse est d'explorer de nouvelles approches pour le développement de systèmes robotiques capables de partager en toute sécurité leur espace de travail avec des opérateurs humains. Dans ce contexte, le travail présenté est axé principalement sur la problématique de commande. Les questions suivantes sont abordées:- pour des lois de contrôle réactives, c'est-à-dire des problèmes de commande où la tâche à exécuter n'est pas connue à l'avance mais découverte en temps réel, comment est-il possible de garantir à chaque pâs de temps l'existence d'une solution au problème de contrôle? Cette solution devrait permettre au robot d'accomplir au mieux sa tâche préscrite et en même temps de strictement respecter les contraintes existantes, parmi lesquelles, les contraintes liées aux limitations physiques des actionneurs de ses articulations.- Comment intégrer l'opérateur humain dans la boucle de contrôle du robot de manière à ce que le contact physique puisse être engagé et désengagé en toute sécurité? Concernant le premier point, notre travail se présente comme la continuité de résultats antérieurs développés par Sébastien Rubrecht lors de sa thèse de doctorat. Sébastien Rubrecht a introduit le concept d'incompatibilité des contraintes pour des robots contrôlés de manière réactive au niveau cinématique. Le problème de l'incompatibilité des contraintes apparaît par exemple lorsque la formulation de la contrainte sur une position articulaire d'un robot ne tient pas compte de la quantité de décélération produite par son actionneur. Dans ce cas, si la contrainte de position articulaire est activée tardivement, le système peut se retrouver dans une situation où il n'a pas suffisamment de temps pour faire face à la limite de position articulaire imposée considérant ses capacités dynamiques limitésThe intended goal of this thesis is to bring new insights for developing robotic systems capable of safely sharing their workspace with human-operators. Within this context, the presented work focuses on the control problem. The following questions are tackled:-for reactive control laws, i.e., control problems where the task to be performed is not known in advance but discovered on-line, how is it possible to guarantee for every time-step the existence of a solution to the control problem? This solution should allow the robot to accomplish at best its prescribed task and at the same time to strictly comply with existing constraints, among which, constraints related to the physical limitations of its actuators and joints.-How to integrate the human-operator in the control loop of the robot so that physical contact can safely be engaged and de-engaged? Regarding the first point, our work arises as the continuity of previous results developed by Sébastien Rubrecht during his PhD thesis. Sébastien Rubrecht introduced the concept of constraints incompatibility for robots reactively controlled at the kinematic-level. The problem of constraints incompatibility appears for example when the formulation of the constraint on an articular position of a robot does not account for the amount of deceleration producible by its actuator. In such case, if the articular position constraint is activated tardively, the system may not have sufficient time to cope with the imposed joint position limit considering its bounded dynamic capabilities
3
Wei, Chen. "Static force capabilities and dynamic capabilities of parallel mechanisms equipped with safety clutches". Master's thesis, Université Laval, 2014. http://hdl.handle.net/20.500.11794/24810.
Testo completoAbstract (sommario):
Cette thèse étudie les forces potentielles des mécanismes parallèles plans à deux degrés de liberté équipés d'embrayages de sécurité (limiteur de couple). Les forces potentielles sont étudiées sur la base des matrices jacobienne. La force maximale qui peut être appliquée à l'effecteur en fonction des limiteurs de couple ainsi que la force maximale isotrope sont déterminées. Le rapport entre ces deux forces est appelé l'efficacité de la force et peut être considéré ; comme un indice de performance. Enfin, les résultats numériques proposés donnent un aperçu sur la conception de robots coopératifs reposant sur des architectures parallèles. En isolant chaque lien, les modèles dynamiques approximatifs sont obtenus à partir de l'approche Newton-Euler et des équations de Lagrange pour du tripteron et du quadrupteron. La plage de l'accélération de l'effecteur et de la force externe autorisée peut être trouvée pour une plage donnée de forces d'actionnement.This thesis investigates the force capabilities of two-degree-of-freedom planar parallel mechanisms that are equipped with safety clutches (torque limiters). The force capabilities are studied based on the Jacobian matrices. The maximum force that can be applied at the end-effector for given torque limits (safety index) is determined together with the maximum isotropic force that can be produced. The ratio between these two forces, referred to as the force effectiveness, can be considered as a performance index. Finally, some numerical results are proposed which can provide insight into the design of cooperation robots based on parallel architectures. Considering each link and slider system as a single body, approximate dynamic models are derived based on the Newton-Euler approach and Lagrange equations for the tripteron and the quadrupteron. The acceleration range or the external force range of the end-effector are determined and given as a safety consideration with the dynamic models.
4
Tan, Yang. "Transitions continues des tâches et des contraintes pour le contrôle de robots". Thesis, Paris 6, 2016. http://www.theses.fr/2016PA066096/document.
Testo completoAbstract (sommario):
Lors du contrôle de robots, les variations fortes et soudaines dans les couples de commande doivent impérativement être évitées. En effet ces discontinuités peuvent entraîner, en plus des comportements imprévisibles du système, des dommages physiques, notamment au niveau des actionneurs. Pour la réalisation de tâches complexes, un robot à plusieurs degrés de liberté utilise généralement un système de commande multi-objectif avec lequel plusieurs tâches doivent être réalisées et plusieurs contraintes respectées. Le basculement entre ces différentes tâches ainsi que les contraintes causées par un environnemt dynamique et imprévisible sont les causes directes des variations fortes dans les couples de commande. Dans ce travail, les problèmes de transitions de priorités entre les différentes tâches ainsi que la variation des contraintes sont considérées avec pour objectif la des variations fortes dans les couples de commande. Deux contributions principales ont été réalisées.Premièrement, un nouveau contrôleur appelé "contrôle hiérarchique généralisé (GHC)" est implémenté sous forme d’optimisation quadratique pour gérer la priorité des transitions entre les tâches de poids différents. Le projecteur utilisé assure en plus de la continuité des transitions, la gestion de l’ajout et/ou de la suppression de tâches. Les couples de commande sont alors calculés en résolvant un problème d’optimisation prenant en compte en même temps la hiérarchie des tâches et les contraintes égalitaire et inégalitaires.Deuxièmement, nous avons développé une primitive de contrôle à base de Contrôle par Modèle Prédictif (CMP) afin de gérer l’existence des discontinuités des contraintes que doit respecter le robot, tel que le changement d’état des contacts ou l’évitement d'obstacles. Le contrôleur profite ainsi de la formulation prédictive en anticipant l'évolution des contraintes vis-à-vis des scénarios de commande et/ou de l'information des capteurs. Il permet de générer des nouvelles contraintes continues qui remplacent les anciennes contraintes discrètes dans le contrôleur réactif QP. Par conséquent, le taux de changement des couples articulaires est minimisé, comparé aux anciennes contraintes discrètes. Cette primitive de contrôle prédictive ne modifie pas directement les objectifs désirés des tâches mais les contraintes, ce qui permet de s’assurer que les changements de couple sont bien gérés dans les pires scénarios.L'efficacité de la stratégie de contrôle proposée est validée via des expériences en simulation avec le robot Kuka LWR 4+ et le robot humanoïde iCub. Les résultats montrent que l'approche développée peut réduire de manière significative la variation des couples articulaires pendant les changements de priorité des tâches ou sous contraintes discrètesLarge and sudden changes in the torques of the actuators of a robot are highly undesirable and should be avoided during robot control as they may result in unpredictable behaviours. Multi-objective control system for complex robots usually have to handle multiple prioritized tasks while satisfying constraints. Changes in tasks and/or constraints are inevitable for robots when adapting to the unstructured and dynamic environment, and they may lead to large sudden changes in torques. Within this work, the problem of task priority transitions and changing constraints is primarily considered to reduce large sudden changes in torques. This is achieved through two main contributions as follows. Firstly, based on quadratic programming (QP), a new controller called Generalized Hierarchical Control (GHC) is developed to deal with task priority transitions among arbitrary prioritized task. This projector can be used to achieve continuous task priority transitions, as well as insert or remove tasks among a set of tasks to be performed in an elegant way. The control input (e.g. joint torques) is computed by solving one quadratic programming problem, where generalized projectors are adopted to maintain a task hierarchy while satisfying equality and inequality constraints. Secondly, a predictive control primitive based on Model Predictive Control (MPC) is developed to handle presence of discontinuities in the constraints that the robot must satisfy, such as the breaking of contacts with the environment or the avoidance of an obstacle. The controller takes the advantages of predictive formulations to anticipate the evolutions of the constraints by means of control scenarios and/or sensor information, and thus generate new continuous constraints to replace the original discontinuous constraints in the QP reactive controller. As a result, the rate of change in joint torques is minimized compared with the original discontinuous constraints. This predictive control primitive does not directly modify the desired task objectives, but the constraints to ensure that the worst case of changes of torques is well-managed. The effectiveness of the proposed control framework is validated by a set of experiments in simulation on the Kuka LWR robot and the iCub humanoid robot. The results show that the proposed approach significantly decrease the rate of change in joint torques when task priorities switch or discontinuous constraints occur
5
Dunton, Alec. "Topological Data Analysis for Systems of Coupled Oscillators". Scholarship @ Claremont, 2016. http://scholarship.claremont.edu/hmc_theses/79.
Testo completoAbstract (sommario):
Coupled oscillators, such as groups of fireflies or clusters of neurons, are found throughout nature and are frequently modeled in the applied mathematics literature. Earlier work by Kuramoto, Strogatz, and others has led to a deep understanding of the emergent behavior of systems of such oscillators using traditional dynamical systems methods. In this project we outline the application of techniques from topological data analysis to understanding the dynamics of systems of coupled oscillators. This includes the examination of partitions, partial synchronization, and attractors. By looking for clustering in a data space consisting of the phase change of oscillators over a set of time delays we hope to reconstruct attractors and identify members of these clusters.
6
Gu, Bei 1970. "Co-simulation of algebraically coupled dynamic subsystems". Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/8695.
Testo completoAbstract (sommario):
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2001.Includes bibliographical references (leaves 108-110).
In the manufacturing industry out-sourcing/integration is becoming an important business pattern (not a clear statement-integration still done in house-component design and manufacturing outsourced). An engineering system often consists of many subsystems supplied by different companies. Bridge between thoughts is weak. Object-oriented modeling is an effective tool for modeling of complex coupled systems. However, subsystem models have to be assembled and compiled before they can produce simulation results for the coupled system. Compiling models into simulations? is time consuming and often requires a profound understanding of the models. Also, the subsystem makers cannot preserve their proprietary information in the compilation process. This research is intended to address this problem by extending object-oriented modeling to object-oriented simulation called co-simulation. Co-Simulation is an environment in which we can simultaneously run multiple independent compiled simulators to simulate a large coupled system. This research studies a major challenge of object-oriented simulation: incompatible boundary conditions between subsystem simulators caused by causal conflicts. The incompatible boundary condition is treated as an algebraic constraint. The high index of the algebraic constraint is reduced by defining a sliding manifold, which is enforced by a discrete-time sliding mode controller. The discrete-time approach fits well with the numerical simulation since it can guarantee numerical stability.
(cont.) A Boundary Condition Coordinator (BCC), which implements the discrete-time controller, makes the incompatible boundary condition compatible. Multi-rate sliding controllers are developed to guarantee the stability of the sliding manifold with any integration step size for the subsystem simulators. A multi- rate sliding mode scheme is specially devised to minimize information disclosure from the subsystem simulators and to facilitate pure numerical computation. The influence of the BCCs on the rest of the subsystem simulators is studied using the input-output linearization theory. The Co-Simulation software environment is developed in Java. Subsystem simulators and BCCs run as independent processes in the Co-Simulation environment. Class templates containing all necessary functions for different types of subsystems are defined. Engineers can easily build a subsystem simulator by simply providing only the mathematical model, which will be hidden after the subsystem simulator is made. Integration engineers can assemble subsystem simulators into simulation of the large coupled system by merely making connections among subsystems. The object-oriented class design makes it possible to extend the Co-Simulation over the Internet or to compile subsystems into a single thread simulator.
by Bei Gu.
Ph.D.
7
ABDEL-MOMEN, SHERIF SAMIR. "DYNAMIC RESOURCE BALANCING BETWEEN TWO COUPLED SIMULATIONS". University of Cincinnati / OhioLINK, 2003. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1060893659.
Testo completo
8
Oliviero, Mattia. "Fertility Decisions in Context - Individual and Couple Dynamics". Doctoral thesis, Università degli studi di Trento, 2019. http://hdl.handle.net/11572/243214.
Testo completoAbstract (sommario):
This thesis contributes to enhance our knowledge on fertility decisions by addressing two major issues. First, it contributes to the understanding of the factors behind the differences in fertility levels among European countries by adopting a holistic perspective. Second, it adds to the fertility topic by examining the whole fertility decision-making process using a dyadic and a life-course perspective to address the ‘fertility gap’ that exists between desired family size and the actual number of children. In order to provide these contributions, this thesis is structured as follows. After a detailed review of the literature, major attention is dedicated to the analysis of the differences in terms of fertility levels between the European countries (Chapter 2). Chapter 3 investigates the fertility decision-making process exploiting the unique information of HILDA, which allows for a dyadic as well as longitudinal analysis of the overall process. The last chapter examines in-depth the transition to parenthood among couples of diverse ethnic origins in Australia.
9
Oliviero, Mattia. "Fertility Decisions in Context - Individual and Couple Dynamics". Doctoral thesis, Università degli studi di Trento, 2019. http://hdl.handle.net/11572/243214.
Testo completoAbstract (sommario):
This thesis contributes to enhance our knowledge on fertility decisions by addressing two major issues. First, it contributes to the understanding of the factors behind the differences in fertility levels among European countries by adopting a holistic perspective. Second, it adds to the fertility topic by examining the whole fertility decision-making process using a dyadic and a life-course perspective to address the ‘fertility gap’ that exists between desired family size and the actual number of children. In order to provide these contributions, this thesis is structured as follows. After a detailed review of the literature, major attention is dedicated to the analysis of the differences in terms of fertility levels between the European countries (Chapter 2). Chapter 3 investigates the fertility decision-making process exploiting the unique information of HILDA, which allows for a dyadic as well as longitudinal analysis of the overall process. The last chapter examines in-depth the transition to parenthood among couples of diverse ethnic origins in Australia.
10
Sun, Hongyan. "Coupled nonlinear dynamical systems". Morgantown, W. Va. : [West Virginia University Libraries], 2000. http://etd.wvu.edu/templates/showETD.cfm?recnum=1636.
Testo completoAbstract (sommario):
Thesis (Ph. D.)--West Virginia University, 2000.Title from document title page. Document formatted into pages; contains xi, 113 p. : ill. (some col.). Includes abstract. Includes bibliographical references.
11
Jacob, Persson. "Dynamics of Coupled Spin and Displacement". Thesis, Uppsala universitet, Materialteori, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-294850.
Testo completoAbstract (sommario):
The dynamics of spin and mechanical displacement in ionic materials are independently well understood. This abstract work aims to investigate the spin and the displacement dynamics of two ions, while including coupled interactions between the ions’ spin and displacement. I have found that the dynamics depend on the speed of both the spin and the displacement.Joners spinn- respektive förflyttningsdynamik har väl etablerade teoretiska grunder. Med syftet att utöka den teoretiska kunskapen undersöker jag hur spinn- och förflyttningsdynamiken hos två joner påverkas av kopplade interaktioner mellan deras spinn och förflyttning. Resultatet visar att dynamiken beror på spinnets och förflyttningens farter.
12
Denman-Johnson, Matthew G. "Dynamics of synaptically coupled McKean neurons". Thesis, Loughborough University, 2004. https://dspace.lboro.ac.uk/2134/36171.
Testo completoAbstract (sommario):
The work in this thesis uses geometric dynamical systems methods to derive phase equations for networks of weakly connected McKean relaxation oscillators. Importantly, this particular single neuron model, with appropriate modifications, is shown to mimic very closely the behaviour of the more biophysically complicated Hodgkin-Huxley model, whilst remaining analytically tractable (albeit in some singular limit). We consider realistic forms of axo-dendritic synaptic coupling with chemical synapses modelled as the convolution of some input spike train with an appropriate temporal kernel. Using explicit forms for the phase response curves (PRCs), for a range of single neuron models, we are able to derive explicit formulas for the phase interaction function in an arbitrary synaptically interacting network of neural oscillators. The PRC for the McKean model is calculated exactly, whilst those for other models is found numerically. In both cases we make extensive use of Fourier representations for synaptic currents, to investigate the effects of axonal, synaptic and dendritic delays on the existence and stability of phase-locked states.
13
Matharu, Satpal. "Charge dynamics in coupled semiconductor superlattices". Thesis, Loughborough University, 2015. https://dspace.lboro.ac.uk/2134/17158.
Testo completoAbstract (sommario):
In this thesis, we investigate the collective electron dynamics in single and coupled superlattice systems under the influence of a DC electric field. Firstly, we illustrate that Bloch oscillations suppress electron transport and the resulting charge domains form self-sustained current oscillations. Upon the application of a tilted magnetic field, stochastic web structures are shown to form in the phase space of the electron trajectory. This occurs only when the Bloch and cyclotron frequencies are commensurate allowing the electrons to demonstrate chaotic unbounded trajectories, leading to an increase in transport. The charge domain dynamics also present additional peaks during such resonances. The rapid changes in the dynamical states found is an example of non-KAM chaos. We show then the amplitude and frequency of current oscillations in a single superlattice can be controlled. Secondly, two models are designed to mutually couple two semiconductor superlattices by a common resistive load. We examine the effects of coupling strength and frequency detuning on the collective current dynamics. The devices are considered to be arranged together on a single substrate as well as on individual substrates. Large AC power is witnessed during anti-phase and in-phase synchronization between current oscillations. Finally, two superlattices are coupled through a resonance circuit incorporating single mode resonances from external influences in the circuit. In this system, chaotic current dynamics are induced with regions of chaos separating different regions of synchronization. High frequency oscillations with minimal phase difference cause the largest power generation. In all three coupling models high frequency components are found in the Fourier power spectra. The power generated in the coupled systems is found greater and at times more than double the power generated in the autonomous superlattice. Thus this thesis provides innovative methods of enhancing and controlling powerful high-frequency signals. This effectively gives manipulation over the intensity of the electromagnetic radiation produced by the superlattice.
14
Shim, Sangyun. "Coupled dynamic analysis of floating offshore wind farms". [College Station, Tex. : Texas A&M University, 2007. http://hdl.handle.net/1969.1/ETD-TAMU-2564.
Testo completo
15
Urgueira, Antonio Paulo Vale. "Dynamic analysis of coupled structures using experimental data". Thesis, Imperial College London, 1990. http://hdl.handle.net/10044/1/46590.
Testo completo
16
Liu, Wenjie. "Structural dynamic analysis and testing of coupled structures". Thesis, Imperial College London, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.246801.
Testo completo
17
Hui, Yau-Chee. "Dynamic studies of proximity coupled Josephson junction arrays /". The Ohio State University, 1993. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487848078449018.
Testo completo
18
Wordsworth, John. "Winnerless competition in neural dynamics : cluster synchronisation of coupled oscillators". Thesis, University of Exeter, 2009. http://hdl.handle.net/10036/87314.
Testo completoAbstract (sommario):
Systems of globally coupled phase oscillators can have robust attractors that are heteroclinic networks. Such a heteroclinic network is generated, where the phases cluster into three groups, within a specific regime of parameters when the phase oscillators are globally coupled using the function $g(\varphi) = -\sin(\varphi + \alpha) + r \sin(2\varphi + \beta)$. The resulting network switches between 30 partially synchronised states for a system of $N=5$ oscillators. Considering the states that are visited and the time spent at those states a spatio-temporal code can be generated for a given navigation around the network. We explore this phenomenon further by investigating the effect that noise has on the system, how this system can be used to generate a spatio-temporal code derived from specific inputs and how observation of a spatio-temporal code can be used to determine the inputs that were presented to the system to generate a given coding. We show that it is possible to find chaotic attractors for certain parameters and that it is possible to detail a genetic algorithm that can find the parameters required to generate a specific spatio-temporal code, even in the presence of noise. In closing we briefly explore the dynamics where $N>5$ and discuss this work in relation to winnerless competition.
19
Katsanis, George R. Mr. "Transient Small Wind Turbine Tower Structural Analysis with Coupled Rotor Dynamic Interaction". DigitalCommons@CalPoly, 2013. https://digitalcommons.calpoly.edu/theses/960.
Testo completoAbstract (sommario):
Structural dynamics is at the center of wind turbine tower design - excessive vibrations can be caused by a wide range of environmental and mechanical sources and can lead to reduced component life due to fatigue, noise, and impaired public perception of system integrity. Furthermore, periodic turbulent wind conditions can cause system resonance resulting in significantly increased structural loads. Structural vibration issues may become exacerbated in small wind applications where the analytical and experimental resources for system verification and optimization are scarce. This study combines several structural analysis techniques and packages them into a novel and integrated form that can be readily used by the small wind community/designer to gain insight into tower/rotor dynamic interaction, system modal characteristics, and to optimize the design for reduced tower loads and cost. The finite element method is used to model the tower structure and can accommodate various configurations including fixed monopole towers, guy-wire supported towers, and gin-pole and strut supported towers. The turbine rotor is modeled using the Equivalent Hinge-Offset blade model and coupled to the tower structure through the use of Lagrange’s Equations. Standard IEC Aeroelastic load cases are evaluated and transient solutions developed using the Modal Superposition Method and Runge-Kutta 4th order numerical integration. Validation is performed through comparisons to theoretical closed form solutions, physical laboratory test results, and peer studies. Finally a case study is performed by using the tool to simulate the Cal Poly Wind Power Research Center Wind Turbine and Tower System. Included in the case study is an optimization for hypothetical guy-wire placement to minimize tower stresses and maximize the tower’s natural frequency.
20
Dies, Miracle Marta. "Coupled dynamical processes in bacteria". Doctoral thesis, Universitat Politècnica de Catalunya, 2015. http://hdl.handle.net/10803/401630.
Testo completoAbstract (sommario):
The main object of this Thesis is the study of the dynamical coupling between cellular processes, and how this coupling gives rise to a well-defined behavior in the presence of non-linearities and noise. Cell functioning relies on the exquisite coordination between a large number of dynamical nonlinear processes subject to fluctuations, which simultaneously operate within the cell. Many cellular dynamical processes occur in the form of periodic oscillations in the expression and/or activation of proteins. However more complex dynamics have been identified recently in the form of transient pulses occurring at random. These types of dynamical processes do not occur in isolation in a cell but they do so simultaneously, and therefore it is necessary to establish the origin and level of coordination between them. All these issues still remain unanswered.
In Part I we introduce and motivate the two types of cellular dynamics studied in this Thesis. Part II is devoted to pulses of protein expression or activity (Chapters 2 and 3), whereas in Part III we concentrate in periodic oscillations in protein expression (Chapter 4). Specifically, in Chapter 2 we focus on how the coupling of certain inputs affect the response of the circuit regulating competence for DNA uptake in Bacillus subtilis. In wild-type cells, under certain environmental stress conditions, competence has been found to follow a stochastic pulsing dynamics. Here we study how the dynamical response of the competence circuit varies from excitable pulses to bistability and oscillations depending on the joint action of two coupled inputs applied to the system. The phenotypical effects reported in this Chapter are caused by changes in the dynamical behavior of the underlying genetic circuit. The stability analysis of a theoretical model of the competence circuit establishes the various dynamical regimes that the circuit can exhibit, which are in very good quantitative agreement with experimental results.
Still dealing with pulsing dynamics, in Chapter 3 we study the dynamical coupling between pulses of protein activity in single cells. For that purpose, in collaboration with Prof. M. Elowitz's laboratory from the California Institute of Technology, we concentrated in the alternative sigma factors family in B. subtilis. Sigma factors are proteins that reversibly bind to core RNA polymerase thus giving the formed holoenzyme promoter-recognition properties. In this Chapter we show for the first time that several alternative sigma factors present stochastic pulses in their activation, and that these pulses take place in conditions of competition for core RNA polymerase. In the light of these results, we propose a new mechanism, ¿time-sharing¿, in which sigma factors take turns in order to use most of the available RNA polymerase, with only one or a few sigma factors being simultaneously active in a given cell. We also develop several mathematical models that shed light on how pulsing and competition affect RNAP allocation.
In Chapter 4 we study how a synthetic genetic oscillator is coupled to cell division and replication. We took advantage of a synthetic oscillator developed for Escherichia coli in the laboratory of Prof. J. Hasty at the University of California San Diego. We have shown that the bacterial cell cycle is able to partially entrain the synthetic oscillations consistently under normal growth conditions, by driving the periodic replication of the genes involved in the oscillator. We have also shown that synchronization between the two periodic processes increases when the synthetic oscillator is coupled back to cell cycle via the expression of an inhibitor of replication initiation. Additionally, we have developed a computational toy model that confirmed this effect. Finally, in Part IV (Chapter 5) we summarize and discuss the main results presented in this Thesis, and suggest directions for future research.L’objectiu d’aquesta Tesi és l’estudi de l’acoblament dinàmic entre processos cel·lulars, i de com aquest acoblament genera un comportament ben definit en presència de no-linealitats i soroll. Un funcionament cel·lular correcte depèn de la coordinació exquisida entre un gran nombre de processos dinàmics no lineals subjectes a fluctuacions, que s’esdevenen simultàniament dins la cèl·lula. Aquests tipus de processos dinàmics no tenen lloc de manera aïllada en una cèl·lula sinó que ocorren de manera simultània, essent per tant necessari establir l’origen i el grau de coordinació entre ells. Totes aquestes qüestions romanen encara sense resposta. A la Part I introduïm i motivem els dos tipus de dinàmiques cel·lulars que hem estudiat en aquesta Tesi. Dediquem la Part II als polsos d’expressió o activitat de proteïnes (Capítols 2 i 3), mentre que ens concentrem en les oscil·lacions periòdiques d’expressió de proteïnes a la Part III (Capítol 4). Concretament, en el Capítol 2 abordem la qüestió sobre com l’acoblament de certs senyals d’entrada afecten la resposta del circuit que regula la competència per a la incorporació d’ADN en Bacillus subtilis. En cèl·lules silvestres i sota determinades condicions d’estrès ambiental, s’ha determinat que l’estat de competència segueix una dinàmica de polsos estocàstics. Aquí estudiem com la resposta dinàmica del circuit de competència varia des de polsos excitables fins a la biestabilitat i les oscil·lacions, depenent de l’acció conjunta de les dues entrades acoblades aplicades al sistema. Els efectes fenotípics reportats en aquest Capítol són causats per canvis en el comportament dinàmic del circuit genètic subjacent. L’anàlisi d’estabilitat d’un model teòric del circuit de competència estableix els diferents règims dinàmics que pot exhibir el circuit, els quals estan quantitativament d’acord amb els resultats experimentals. Seguint amb dinàmiques de polsos, al Capítol 3 estudiem l’acoblament dinàmic entre polsos d’activitat de proteïnes en cèl·lules individuals. A aquest efecte, en col·laboració amb el laboratori del Prof. M. Elowitz de l’Institut de Tecnologia de Califòrnia, vàrem concentrar-nos en la família de factors sigma alternatius en B. subtilis. Els factors sigma són proteïnes que s’uneixen a l’ARN polimerasa de manera reversible, fent possible el reconeixement de promotors específics per part de l’holoenzim format. En aquest Capítol mostrem que diversos factors sigma alternatius presenten polsos estocàstics en la seva activació, i que aquests polsos competeixen per l’ARN polimerasa. A la llum d’aquests resultats proposem un nou mecanisme de repartiment, que anomenem en anglès “time-share”, pel qual els factors sigma fan torns en el temps per utilitzar la majoria d’ARN polimerasa disponible. D’aquesta manera, només un o molt pocs factors sigma estarien actius simultàniament en una mateixa cèl·lula. També hem desenvolupat una sèrie de models matemàtics que revelen com els polsos i la competició afecten la distribució de l’ARN polimerasa. Al Capítol 4 estudiem com un oscil·lador genètic sintètic està acoblat a la replicació i la divisió cel·lular. Vam utilitzar l’oscil·lador sintètic desenvolupat per a Escherichia coli al laboratori del Prof. J. Hasty a la Universitat de Califòrnia San Diego. Mostrem com el cicle cel·lular bacterià és capaç d’entrenar parcialment les oscil·lacions sintètiques de manera consistent en condicions de creixement normal, tot dirigint la replicació periòdica dels gens involucrats en l’oscil·lador. També exposem que la sincronització entre els dos processos periòdics s’incrementa si l’oscil·lador sintètic es retroacobla al cicle cel·lular mitjançant l’expressió d’un inhibidor de la iniciació de la replicació. A més, hem desenvolupat un model computacional simplificat que confirma aquest efecte. Finalment, a la Part IV (Capítol 5) resumim i discutim els principals resultats presentats en aquesta Tesi, i suggerim direccions futures cap a on ampliar la recerca.
21
Garira, Winston. "Synchronisation of coupled dynamical systems". Thesis, University of London, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.399495.
Testo completo
22
Heath, Ted H. "Synchronization and phase dynamics of coupled oscillators". Diss., Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/30310.
Testo completo
23
Reed, Rebecca Ginny. "Interpersonal Immune and Emotion Dynamics in Couples". Diss., The University of Arizona, 2015. http://hdl.handle.net/10150/556225.
Testo completoAbstract (sommario):
Social relationships affect a range of health outcomes, including even mortality risk. However, important questions remain concerning the precise mechanisms through which close relationships exert their influence. The present research focuses specifically on immunological and interpersonal emotion processes that may link social relationships and health. The specific aims of this study were to: (1) determine: a) how long it takes for adults' inflammatory levels to recover after an interpersonal laboratory stressor, and b) whether there are associations between allostatic load indicators of cardiovascular functioning and lipid/fat metabolism and immune recovery; (2) determine whether partners' immune patterns are linked, above and beyond the expected diurnal rhythm; and (3) examine the moderating effects of interpersonal emotion regulation patterns on partners' immune functioning. A final goal of the present study was to test the feasibility of conducting such a study in a naturalistic setting with multiple ambulatory immune measures per day, across multiple days. Twenty-four committed heterosexual couples collected their own salivary immune samples 4 times each day (upon waking, mid-morning, later afternoon, and before bed) for 5 consecutive days, including 2 days before a laboratory dyadic stressor (discussing an area of disagreement in the relationship), the day of, and 2 days after, to capture normative baseline diurnal variability and immune recovery post-stressor. Four additional saliva samples were collected on the lab stressor day at baseline, immediately after the disagreement conversation, 30-min. post-conversation, and 90-min. post conversation, for a total of 8 samples collected on the lab stressor day. Salivary samples were assayed for interleukin(IL)-6 using ELISAs (Salimetrics, LLC). As predicted, after the interpersonal laboratory stressor, immune recovery occurred within 48 hours of the stressor, and in fact recovered as early as the evening of the stressor. However, on the day of the lab stressor, IL-6 levels appeared to still be elevated at the later afternoon time point, approximately 3 hours after the stressor had ended. Contrary to my hypothesis, allostatic load indicators of cardiovascular functioning and lipid/fat metabolism did not moderate immune recovery. Secondly, as expected, partners displayed physiological (immune) linkage; specifically, couples showed "anti-phase" physiological linkage on the day of the lab stressor, and "in-phase" linkage on all other days, pooled together, suggesting that couples may have engaged in more of a regulatory effort on the day of the lab stressor, whereas on all other days, there was a relaxation of regulation and enhanced emotional connection. Third, couples' interpersonal emotion dynamics moderated the diurnal pattern of IL-6 such that couples who exhibited disconnected negative emotions, disconnected positive emotions, and displayed indeterminate patterns in their positive emotions, showed dysregulated diurnal IL-6 slopes. Lastly, the methodology of the present study proved to be feasible, and the study was accomplished without unforeseen problems. Ultimately, studying these immune and emotion processes as they occur in every-day life may help to uncover patterns in couples' biology and emotions that may accumulate over time to set people on different health trajectories.
24
Beasley, Benjamin S. "Coupled Barrier Island Shoreline and Shoreface Dynamics". ScholarWorks@UNO, 2018. https://scholarworks.uno.edu/td/2508.
Testo completoAbstract (sommario):
In Louisiana, barrier islands are undergoing morphological change driven by high rates of relative sea-level rise and interior wetland loss. Previous works utilized historical region-scale bathymetry and shoreline change analyses to assess coastal evolution. However, more localized assessments considering the role of sediment transport processes in regional evolution are lacking. This is essential to predicting coastal change trajectories and allocating limited sand resources for nourishment. Using bathymetric and shoreline data, 100-m spaced shore-normal transects were created to track meter-scale elevation change for 1880s, 1930s, 1980s, 2006, and 2015. An automated framework was used to quantify and track parameters such as shoreline change, barrier island area and width, bathymetric isobath migration, and shoreface slope. Our results illustrate that monitoring subaerial island erosion rates are insufficient for evaluating regional sediment dynamics of transgressive coastal systems. Advances in understanding these processes will facilitate more informed planning, management, and mitigation of transgressive barrier islands.
25
Adams, Daniel J. "Magnetization Dynamics in Coupled Thin Film Systems". ScholarWorks@UNO, 2019. https://scholarworks.uno.edu/td/2578.
Testo completoAbstract (sommario):
A study is presented detailing experimental investigations of magnetization dynamics in nanostructured systems which are coupled magnetically. This work seeks to characterize the anisotropy of such systems through experimental techniques which probe microwave resonant absorption in the materials.
A custom-built experimental setup, designed and assembled in our labs, is explained in detail. This setup allows for angular-dependent ferromagnetic resonance (FMR) measurements in the sample plane through vector network analyzer spectroscopy and is adaptable to two different types of coplanar waveguides. This technique has proven effective for characterization of multiple types of magnetic systems, including multilayered structures as detailed here, with different types of anisotropies while allowing us to draw analogies with more common characterization techniques. The angular FMR setup has been used to study coupled systems, such as those coupled through the Ruderman–Kittel–Kasuya–Yosida interaction as well as exchange-biased structures. These types of coupled systems have technological impacts and are highly applied in the components of magnetoresistive random access memory. Using this new characterization technique, properties of synthetic antiferromagnets have been revealed which had not been observed before.
In addition to these experiments, magnetic susceptibility and FMR in exchange biased systems have been investigated at temperatures as low as 2 K. This investigation used a new FMR spectrometer and was one of the first studies to use this instrument.
For the first time a new method of identifying several types of coupling which can be present in layered nanostructures is presented and supported through comparison with known techniques, thus connecting a new characterization technique for layered structures with decades-old procedures. Many results within this work are also supported theoretically with computer simulations.
26
Scuse, Paul Donald. "The odd couple, a developmental perspective in pastoral relationship dynamics". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0003/NQ40323.pdf.
Testo completo
27
Tierney, Christopher John. "Non-linear dynamics of couple SQUID ring : tank circuit systems". Thesis, University of Sussex, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.360589.
Testo completo
28
Rose, Alexander. "The dynamic coupling interface of G-protein coupled receptors". Doctoral thesis, Humboldt-Universität zu Berlin, Lebenswissenschaftliche Fakultät, 2015. http://dx.doi.org/10.18452/17215.
Testo completoAbstract (sommario):
Um mit ihrer Umgebung zu kommunizieren verfügen lebende Zellen über Rezeptoren, welche die umschließende Membran überbrücken. Die vorherrschende G-Protein-gekoppelte Rezeptoren (GPCR) erhalten Informationen von Außerhalb durch Bindung eines Liganden, wodurch der Rezeptor aktiviert wird. Während der Aktivierung bildet sich innerzellulär ein offener Spalt, in den ein G-Protein (Gαβγ, G) mit seinem C-terminalen Ende koppeln kann. Die Bindung an einen GPCR führt in der Gα-Untereinheit vom Gαβγ zu einen GDP/GTP-Austausch, welcher für die weitere Signalübertragung ins Zellinnere notwendig ist. Die Kopplung von Rezeptor und Gαβγ umfasst eine Reihe von dynamischen strukturellen Änderungen, die Geschwindigkeit und Spezifität der Interaktion regeln. Hier haben wir MD-Simulationen (Molekulardynamik) verwendet, um die molekularen Details der GPCR Gαβγ Kopplung vor und während der GPCR-Gαβγ-Komplexbildung bis hin zum GDP/GTP-Austausch zu untersuchen.To communicate with their environment, living cells feature receptors that provide a bridge across the enclosing membrane. The prevalent G protein-coupled receptors (GPCR) receive outside information through the binding of a ligand, which activates the receptor. During activation, an open intracellular crevice forms, to which a G protein (Gαβγ, G) can couple with its Gα C-terminus. Binding to GPCRs triggers GDP/GTP exchange in the Gα subunit of Gαβγ, necessary for further signal transfer within the cell. The coupling between receptor and Gαβγ involves a series of dynamic structural changes that govern speed and specificity of the interaction. Here we used molecular dynamics (MD) simulations to elucidate molecular details of the GPCR Gαβγ coupling process before and during GPCR Gαβγ complex formation up to the GDP/GTP exchange.
29
Restrepo, Juan Gabriel. "Dissertation prospectus : dynamics on networks of coupled oscillators". College Park, Md. : University of Maryland, 2005. http://hdl.handle.net/1903/2425.
Testo completoAbstract (sommario):
Thesis (Ph. D.) -- University of Maryland, College Park, 2005.Thesis research directed by: Applied Mathematics and Scientific Computation Program. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
30
Sanchez, Jose Luis Hernandez. "A Study of Dynamics of Coupled Nonlinear Circuits". Diss., Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/6984.
Testo completoAbstract (sommario):
We consider a type of forced "Van Der Pol" oscillator where the forced function is periodic and oscillatory around the t-axis. This problem derived from an electrical model. The important issues here is that this circuits presents the spiking phenomena over a one time period and it has important applications in signal processing and digital communication. The three most important problems that we addressed here in this thesis are to compute the number of spikes a solution completes in one time period (it can be used to transform the analog signal into digital information), how the dynamics of the number of spikes change with respect to the parameters amplitude (k) and frequency (w), and when the coupled circuits synchronize (i.e., the driver and the respond are on synchronous). Sophisticated mathematical and numerical analysis has been developed that enable us to give a complete study of the problems above described.
31
Bitar, Diala. "Collective dynamics of weakly coupled nonlinear periodic structures". Thesis, Bourgogne Franche-Comté, 2017. http://www.theses.fr/2017UBFCD002/document.
Testo completoAbstract (sommario):
Bien que la dynamique des réseaux périodiques non-linéaires ait été investiguée dans les domainestemporel et fréquentiel, il existe un réel besoin d’identifier des relations pratiques avec lephénomène de la localisation d’énergie en termes d’interactions modales et topologies de bifurcation.L’objectif principal de cette thèse consiste à exploiter le phénomène de la localisation pourmodéliser la dynamique collective d’un réseau périodique de résonateurs non-linéaires faiblementcouplés.Un modèle analytico-numérique a été développé pour étudier la dynamique collective d’unréseau périodique d’oscillateurs non-linéaires couplés sous excitations simultanées primaire et paramétrique,où les interactions modales, les topologies de bifurcations et les bassins d’attraction ontété analysés. Des réseaux de pendules et de nano-poutres couplés électrostatiquement ont étéinvestigués sous excitation extérieure et paramétrique, respectivement. Il a été démontré qu’enaugmentant le nombre d’oscillateurs, le nombre de solutions multimodales et la distribution desbassins d’attraction des branches résonantes augmentent. Ce modèle a été étendu pour investiguerla dynamique collective des réseaux 2D de pendules couplés et de billes sphériques en compressionsous excitation à la base, où la dynamique collective est plus riche avec des amplitudes de vibrationplus importantes et des bandes passantes plus larges. Une deuxième investigation de cettethèse consiste à identifier les solitons associés à la dynamique collective d’un réseau périodique etd’étudier sa stabilitéAlthough the dynamics of periodic nonlinear lattices was thoroughly investigated in the frequencyand time-space domains, there is a real need to perform profound analysis of the collectivedynamics of such systems in order to identify practical relations with the nonlinear energy localizationphenomenon in terms of modal interactions and bifurcation topologies. The principal goal ofthis thesis consists in exploring the localization phenomenon for modeling the collective dynamicsof periodic arrays of weakly coupled nonlinear resonators.An analytico-numerical model has been developed in order to study the collective dynamics ofa periodic coupled nonlinear oscillators array under simultaneous primary and parametric excitations,where the bifurcation topologies, the modal interactions and the basins of attraction havebeen analyzed. Arrays of coupled pendulums and electrostatically coupled nanobeams under externaland parametric excitations respectively were considered. It is shown that by increasing thenumber of coupled oscillators, the number of multimodal solutions and the distribution of the basinsof attraction of the resonant solutions increase. The model was extended to investigate the collectivedynamics of periodic nonlinear 2D arrays of coupled pendulums and spherical particles underbase excitation, leading to additional features, mainly larger bandwidth and important vibrationalamplitudes. A second investigation of this thesis consists in identifying the solitons associated tothe collective nonlinear dynamics of the considered arrays of periodic structures and the study oftheir stability
32
Fabiny, Larry. "Dynamics of a coupled solid state laser array". Diss., Georgia Institute of Technology, 1992. http://hdl.handle.net/1853/30509.
Testo completo
33
Doster, Juliane [Verfasser]. "Dynamics of coupled nanomechanical pillar resonators / Juliane Doster". Konstanz : KOPS Universität Konstanz, 2021. http://d-nb.info/1229727388/34.
Testo completo
34
Hernández, José Luis Sánchez. "A study of dynamics of coupled nonlinear circuits". Available online, Georgia Institute of Technology, 2005, 2004. http://etd.gatech.edu/theses/available/etd-12192004-194550/unrestricted/sanchez%5Fjose%5Fl%5F200505%5Fphd.pdf.
Testo completoAbstract (sommario):
Thesis (Ph. D.)--Mathematics, Georgia Institute of Technology, 2005.Feodor Vainstein, Committee Member ; Dieci Luca, Committee Member ; Yi Yingfei, Committee Member ; Wang Yang, Committee Member ; Shui-Nee, Chow, Committee Chair. Vita. Includes bibliographical references.
35
Tong, William. "Coupled Rigid Body Dynamics with Application to Diving". Thesis, The University of Sydney, 2015. http://hdl.handle.net/2123/14577.
Testo completoAbstract (sommario):
Platform and springboard diving is a sport involving athletes falling or jumping into a pool of water, usually while performing acrobatic manoeuvres. At the highest level it challenges the physical laws of gravity as athletes try to outperform each other by executing more sophisticated dives. With a mathematical model we are able to assist the athletes and coaches by providing some insight into the mechanics of diving, which hopefully gives them an edge during competition. In this thesis we begin with an introduction to rigid body dynamics and then extend the results to coupled rigid bodies. We generalise Euler's equations of motion and equations of orientation for rigid bodies to be applicable for coupled rigid bodies. The athlete is represented as a mathematical model consisting of ten simple geometric solids, which is used to conduct three projects within this thesis. In the first project we look at somersaults without twists, which provides a significant reduction as the model becomes planar. The equations of motion and equations of orientation reduce from vector form to a single scalar differential equation for orientation, since angular momentum is conserved. We digitise footage of an elite diver performing 107B (forward 3.5 somersault in pike) from the 3m springboard, and feed that data into our model for comparison between the theoretically predicted and observed result. We show that the overall rotation obtained by the athlete through somersault is composed of two parts, the major contribution coming from the dynamic phase and a small portion from the geometric phase. We note that by modifying the digitised dive slightly we can leave the dynamic phase intact, but change the geometric phase to provide a small boost in overall rotation. The technique involved in doing so is not practical for actual diving though, so we move away from this idea and devise another way of optimising for the overall rotation. We find that by shape changing in a particular way that takes slightly longer than the fastest way of moving into and out of pike, the overall rotation achieved can be improved by utilising the geometric phase. In the second project we use the model to simulate divers performing forward m somersaults with n twists. The formulas derived are general, but we will specifically look at 5132D, 5134D, 5136D, and 5138D (forward 1.5 somersaults with 1, 2, 3, and 4 twists) dives. To keep the simulation as simple as possible we reduce the segment count to two by restricting the athlete to only using their left arm about the abduction-adduction plane of motion. We show how twisting somersaults can be achieved in this manner using this simple model with predetermined set of motor actions. The dive mechanics consist of the athlete taking off in pure somersaulting motion, executing a shape change mid-flight to get into twist position, perform twisting somersaults in rigid body motion, and then executing another shape change to revert the motion back into pure somersaulting motion to complete the dive. In the third and final project we use our model to show how a 513XD dive (forward 1.5 somersaults with 5 twists) is performed. This complicated dive differs from all currently performed dives in that once the diver initiates twist in the somersaulting motion via shape change, they need to perform another appropriately timed shape change to speed up the twist rather than stopping the twist, and only then is five twists obtainable with practical parameters. Such techniques can be found in aerial skiing where the airborne time is longer, but our theory shows that it may also be applicable to platform and springboard diving too. To date, no athlete has ever attempted a 513XD in competition, nor does the International Swimming Federation (FINA) cover dives with five twists in their degree-of-difficulty formula. Our theory shows that 513XD dive is theoretically possible, and with extrapolation we estimate it would have a degree-of-difficulty of 3.9.
36
Bano, Rakhshinda. "Coupled human-water interactions in formal-informal dynamics". Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2023. https://ro.ecu.edu.au/theses/2697.
Testo completoAbstract (sommario):
Urban water supply systems in developing world are complex due to the involvement of numerous stakeholders, compounded by poor management, exacerbated by the impacts of population and economic growth as well as climate change. As a result, there is a need to comprehensively comprehend the complex interactions between humans and water, especially as formal-informal water supply dynamics continue to emerge. This understanding is crucial in informing policy decisions that support the advancement of sustainable urban water systems. Therefore, analysing the coevolving dynamics and feedbacks associated with water systems where formal and informal components coexist is essential.
To better comprehend the intricacies of human-water interactions in developing countries, an integrated System Dynamics (SD) model has been developed. This model employs both qualitative and quantitative systems modelling techniques. Causal Loop Diagrams (CLDs) are utilized to display the relationships and identify system behaviour patterns, which are also known as system archetypes. Meanwhile, stock and flow diagrams are used in Stella Architect to quantify interlinkages. To verify the model, expert consultations, re-evaluation of data from government and private research organizations, statistical data analysis, and mapping of land use and land cover change (LULC) are utilized.
The findings indicate that the coexistence of formal and informal water systems can give rise to common system patterns or archetypes that have implications for the future of urban water management. These archetypes include 'fixes that fail', 'shifting the burden', 'limits to growth/success', and 'growth and underinvestment'. Quantification of these interactions revealed a weak association between informal demand and lower formal tariff recovery rates, with household income playing a significant role. The financial balance of the formal water supply system (FWSS) seems to be less influenced by tariff recovery rates and more dependent on infrastructure condition.
The presence of informal water supply systems is observed to decrease the reliability of the overall system due to higher inflation rates, increased theft by informal suppliers, and lower informal supply capacity. The supply-demand gap is further exacerbated by seasonal water supply changes and competing agricultural demands, which could be addressed by improving agricultural efficiency. To achieve integrated urban water management, it is essential to understand the boundaries of the system and the interactions among its components, in order to make changes to the urban water balance.
To achieve our goal of providing a comprehensive and integrated approach to evaluating formal-informal water supply dynamics at the urban level, we aggregated our assessments at multiple levels, thereby minimizing heterogeneities such as differences among socio-economic groups in evaluating household demand, variations in non-domestic users such as commercial and industrial, types of informal suppliers, and water quantity and quality. This study primarily aims to provide a general overview of how formal and informal water supply systems at a broader level contribute to defining urban water supply reliability and how this reliability is impacted by other variables in the system over time.
37
Hughes, John K. "The dynamic response of the global atmosphere-vegetation coupled system". Thesis, University of Reading, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.397768.
Testo completo
38
Hassan, Mohamed. "INELASTIC DYNAMIC BEHAVIOR AND DESIGN OF HYBRID COUPLED WALL SYSTEMS". Doctoral diss., University of Central Florida, 2004. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4437.
Testo completoAbstract (sommario):
A key consideration in seismic design of buildings is to ensure that the lateral load resisting system has an appropriate combination of strength, stiffness and energy dissipation capacity. Hybrid coupled wall systems, in which steel beams are used to couple two or more reinforced concrete shear walls in series, can be designed to have these attributes and therefore have the potential to deliver good performance under severe seismic loading. This research presents an investigation of the seismic behavior of this type of structural system. System response of 12- and 18-story high prototypes is studied using transient finite element analyses that accounts for the most important aspects of material nonlinear behavior including concrete cracking, tension stiffening, and compressive behavior for both confined and unconfined concrete as well as steel yielding. The developed finite element models are calibrated using more detailed models developed in previous research and are validated through numerous comparisons with test results of reinforced concrete walls and wall-beam subassemblages. Suites of transient inelastic analyses are conducted to investigate pertinent parameters including hazard level, earthquake record scaling, dynamic base shear magnification, interstory drift, shear distortion, coupling beam plastic rotation, and wall rotation. Different performance measures are proposed to judge and compare the behavior of the various systems. The analyses show that, in general, hybrid coupled walls are particularly well suited for use in regions of high seismic risk. The results of the dynamic analyses are used to judge the validity of and to refine a previously proposed design method based on the capacity design concept and the assumption of behavior dominated by the first vibration mode. The adequacy of design based on the pushover analysis procedure as promoted in FEMA-356 (2000) is also investigated using the dynamic analysis results. Substantial discrepancies between both methods are observed, especially in the case of the 18-story system. A critical assessment of dynamic base shear magnification is also conducted, and a new method for estimating its effects is suggested. The method is based on a modal combination procedure that accounts for presence of a plastic hinge at the wall base. Finally, the validity of limitations in FEMA-368 (2000) on building height, particularly for hybrid coupled wall systems, is discussed.Ph.D.
Department of Civil and Environmental Engineering
Engineering and Computer Science
Civil and Environmental Engineering
39
Huang, Elaine Annabelle 1981. "Dynamic analysis of concrete coupled wall structures : a parametric study". Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/31116.
Testo completoAbstract (sommario):
Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2005.Pages [34]-[104] numbered by hand on odd-numbered p.
Includes bibliographical references (p. 32-33).
Concrete coupled wall structure is a system that can efficiently dissipate energy under the effect of lateral loads. It has been widely used in medium height buildings for several decades. While researchers have conducted both experimental and analytical investigations in order to improve the performance of concrete shear wall, there is a lack of systematic comparison of coupled wall behavior due to variation of parameters. Therefore, this report will carry out a parametric study by varying the height of the building, the degree of coupling (DC), and the shape of the wall piers. A computer-simulated study was carried out on the performance of coupled wall structures. The research process was divided into two phases with the first focusing on only on the shear wall system and the second on the interaction between the building and the core shear wall structure. Static pushover analysis was applied in Phase I, and acceleration response spectrum was employed in Phase II. The comparison of the results from both phases provided valuable insight on the structural behaviors of shear walls. The Phase I results showed that C-shaped coupled wall were more efficient than rectangular wall piers. From further investigation in Phase II, it was found that C-shaped wall with 15 degree opening could achieve the greatest stiffness. Same-size coupling beams could create DC in shorter buildings in Phase I, but the result was contradicted in Phase II testing. However, both Phases displayed the fact that shear stiffness played a more important role in affecting DC than flexural stiffness.
(cont.) Pushover analysis and response spectrum analysis both suggested that the DC of coupled wall structure decreased after concrete cracked and the horizontal force was then withstood by base moment. While concrete shear wall reduced lateral deflection of buildings, Phase II displayed the fact that floor frames could bend and form a sagging shape when interacting with coupled walls in an earthquake. Further study can be focused on more detailed modeling to investigate the behavior of concrete shear walls for efficient and economic design.
by Elaine Annabelle Huang.
M.Eng.
40
Withee, Jon E. "Fully coupled dynamic analysis of a floating wind turbine system". Thesis, Monterey, California. Naval Postgraduate School, 2004. http://hdl.handle.net/10945/1471.
Testo completoAbstract (sommario):
CIVINSThe use of wind power is in a period of rapid growth worldwide and wind energy systems have emerged as a promising technology for utilizing offshore wind resources for the large scale generation of electricity Drawing upon the maturity of wind turbine and floater technologies developed by the wind energy and oil and gas industries, respectively, large offshore wind energy systems have been developed and are being proposed for operation in offshore areas where environmental restrictions are less restrictive, large wind resources exist, and open sea areas are available for wind farm development. A fully coupled dynamic analysis/technique was developed to predict the response of a floating wind turbine system in a stochastic wind and wave environment This technique incorporated both non-linear wave loading on the submerged floater and the aerodynamic loading on the wind turbine A tension leg spar buoy was designed to support the wind turbine This design was chosen due to its relatively small size and hence lower potential cost per wind turbine The system's tethers were attached to the ends of spokes which radiated out from the spar cylinder This arrangement of lines and spokes promised to be very stiff in the roll and pitch modes of motion.
41
Li, Yuwei. "Coupled computational fluid dynamics/multibody dynamics method with application to wind turbine simulations". Diss., University of Iowa, 2014. https://ir.uiowa.edu/etd/4681.
Testo completoAbstract (sommario):
A high fidelity approach coupling the computational fluid dynamics method (CFD) and multi-body dynamics method (MBD) is presented for aero-servo-elastic wind turbine simulations. The approach uses the incompressible CFD dynamic overset code CFDShip-Iowa v4.5 to compute the aerodynamics, coupled with the MBD code Virtual.Lab Motion to predict the motion responses to the aerodynamic loads. The IEC 61400-1 ed. 3 recommended Mann wind turbulence model was implemented in this thesis into the code CFDShip-Iowa v4.5 as boundary and initial conditions, and used as the explicit wind turbulence for CFD simulations. A drivetrain model with control systems was implemented in the CFD/MBD framework for investigation of drivetrain dynamics. The tool and methodology developed in this thesis are unique, being the first time with complete wind turbine simulations including CFD of the rotor/tower aerodynamics, elastic blades, gearbox dynamics and feedback control systems in turbulent winds.
Dynamic overset CFD simulations were performed with the benchmark experiment UAE phase VI to demonstrate capabilities of the code for wind turbine aerodynamics. The complete turbine geometry was modeled, including blades and approximate geometries for hub, nacelle and tower. Unsteady Reynolds-Averaged Navier-Stokes (URANS) and Detached Eddy Simulation (DES) turbulence models were used in the simulations. Results for both variable wind speed at constant blade pitch angle and variable blade pitch angle at fixed wind speed show that the CFD predictions match the experimental data consistently well, including the general trends for power and thrust, sectional normal force coefficients and pressure coefficients at different sections along the blade.
The implemented Mann wind turbulence model was validated both theoretically and statistically by comparing the generated stationary wind turbulent field with the theoretical one-point spectrum for the three components of the velocity fluctuations, and by comparing the expected statistics from the simulated turbulent field by CFD with the explicit wind turbulence inlet boundary from the Mann model.
The proposed coupled CFD/MBD approach was applied to the conceptual NREL 5MW offshore wind turbine. Extensive simulations were performed in an increasing level of complexity to investigate the aerodynamic predictions, turbine performance, elastic blades, wind shear and atmospheric wind turbulence. Comparisons against the publicly available OC3 simulation results show good agreements between the CFD/MBD approach and the OC3 participants in time and frequency domains. Wind turbulence/turbine interaction was examined for the wake flow to analyze the influence of turbulent wind on wake diffusion.
The Gearbox Reliability Collaborative project gearbox was up-scaled in size and added to the NREL 5MW turbine with the purpose of demonstrating drivetrain dynamics. Generator torque and blade pitch controllers were implemented to simulate realistic operational conditions of commercial wind turbines. Interactions between wind turbulence, rotor aerodynamics, elastic blades, drivetrain dynamics at the gear-level and servo-control dynamics were studied, showing the potential of the methodology to study complex aerodynamic/mechanic systems.
42
Huynh, Quang-Nghi. "CoModels, engineering dynamic compositions of coupled models to support the simulation of complex systems". Thesis, Paris 6, 2016. http://www.theses.fr/2016PA066565/document.
Testo completoAbstract (sommario):
L'objectif initial de cette thèse est d'apporter une solution à ce problème en proposant, premièrement, une approche cognitive basée sur le paradigme appelé Belief-Desire-Intention (BDI) pour représenter les processus de prise de décision des acteurs humains, et deuxièmement, une validation de cette approche dans le contexte d'un modèle complet de changement d'usage des sols dans lequel la plupart des facteurs cités ci-dessus sont également simulés. Le résultat de ce travail est une approche générique qui a été validée sur un modèle intégrant le changement d'usage des sols d'une région située dans le Delta du Mékong au Vietnam. Nos contributions principales sont les suivantes : Intégration d'une architecture BDI au sein d'une plateforme de modélisation à base d'agents (GAMA) ; Conception d'un cadre générique baptisé " Multi-Agent Based Land-Use Change " (MAB-LUC) permettant de modéliser et de simuler les changements d'usage des sols en prenant en compte les décisions des agriculteurs ; Proposition d'une solution permettant d'intégrer et d'évaluer les facteurs socio-économiques et environnementaux dans le cadre de la planification agraire et d'intégrer MAB-LUC dans le processus existant proposé par la FAO. Ce travail, au-delà du cas d'étude concernant le Delta du Mékong, a enfin été conçu de façon générique afin que la méthodologie utilisée puisse être généralisée à la modélisation de systèmes socio-écologiques où les facteurs humains doivent être représentés avec précisionIntegrated modeling approaches (multi-simulation, multimodeling, etc.) have proven challenging in practice. The first challenge deals with the technical aspects of coupling different computational or mathematical components. The second challenge lies in the alignment of the semantics of these components so that their integration does make sense, which is particularly critical in pluridisciplinary models. A number of approaches have been proposed in the last 20 years but none of them is really suitable to our context . We propose in this thesis an alternate approach, called co-modeling, which borrows concepts and tools from agent-based modeling, agent-oriented software engineering and multimodel ecologies. Simply speaking, a co-model can be defined as a multi-agent system of models and datasets. Each model or dataset is represented by one or several agents interacting with one another within the context of a larger representation of their — potentially dynamic — environment. The proposed approach does not aim at providing a general solution to the two challenges above, but at providing a framework in which modelers can easily implement their solution or test different coupling solutions. The proposed approach is fully implemented within the GAMA agent-based modeling platform. Its advantages are shown in terms of flexibility, composability and reusability in a number of case studies. The first case study is the dynamic coupling of equation-based and agent-based models to obtain “switching” models dynamically. The second one is the design of a complex integrated model where three formalisms and four modeling approaches have been successfully coupled
43
De, Queiroz Lima Roberta. "Modeling and simulation in nonlinear stochastic dynamic of coupled systems and impact". Thesis, Paris Est, 2015. http://www.theses.fr/2015PEST1049/document.
Testo completoAbstract (sommario):
Dans cette Thèse, la conception robuste avec un modèle incertain d'un système électromécanique avec vibro-impact est fait. Le système électromécanique est constitué d'un chariot, dont le mouvement est excité par un moteur à courant continu et un marteau embarqué dans ce chariot. Le marteau est relié au chariot par un ressort non linéaire et par un amortisseur linéaire, de façon qu'un mouvement relatif existe entre eux. Une barrière flexible linéaire, placé à l'extérieur du chariot limite les mouvements de marteau. En raison du mouvement relatif entre le marteau et la barrière, impacts peuvent se produire entre ces deux éléments. Le modèle du système développé prend en compte l'influence du courant continu moteur dans le comportement dynamique du système. Certains paramètres du système sont incertains, tels comme les coefficients de rigidité et d'amortissement de la barrière flexible. L'objectif de la Thèse est de réaliser une optimisation de ce système électromécanique par rapport aux paramètres de conception afin de maximiser l'impact puissance sous la contrainte que la puissance électrique consommée par le moteur à courant continu est inférieure à une valeur maximale. Pour choisir les paramètres de conception dans le problème d'optimisation, une analyse de sensibilité a été réalisée afin de définir les paramètres du système les plus sensibles. L'optimisation est formulée dans le cadre de la conception robuste en raison de la présence d'incertitudes dans le modèle. Les lois de probabilités liées aux variables aléatoires du problème sont construites en utilisant le Principe du Maximum l'Entropie et les statistiques de la réponse stochastique du système sont calculées en utilisant la méthode de Monte Carlo. L'ensemble d'équations non linéaires sont présentés, et un solveur temporel adapté est développé. Le problème d'optimisation non linéaire stochastique est résolu pour différents niveaux d'incertitudes, et aussi pour le cas déterministe. Les résultats sont différents, ce qui montre l'importance de la modélisation stochastiqueIn this Thesis, the robust design with an uncertain model of a vibro-impact electromechanical system is done. The electromechanical system is composed of a cart, whose motion is excited by a DC motor (motor with continuous current), and an embarked hammer into this cart. The hammer is connected to the cart by a nonlinear spring component and by a linear damper, so that a relative motion exists between them. A linear flexible barrier, placed outside of the cart, constrains the hammer movements. Due to the relative movement between the hammer and the barrier, impacts can occur between these two elements. The developed model of the system takes into account the influence of the DC motor in the dynamic behavior of the system. Some system parameters are uncertain, such as the stiffness and the damping coefficients of the flexible barrier. The objective of the Thesis is to perform an optimization of this electromechanical system with respect to design parameters in order to maximize the impact power under the constraint that the electric power consumed by the DC motor is lower than a maximum value. To chose the design parameters in the optimization problem, an sensitivity analysis was performed in order to define the most sensitive system parameters. The optimization is formulated in the framework of robust design due to the presence of uncertainties in the model. The probability distributions of random variables are constructed using the Maximum Entropy Principle and statistics of the stochastic response of the system are computed using the Monte Carlo method. The set of nonlinear equations are presented, and an adapted time domain solver is developed. The stochastic nonlinear constrained design optimization problem is solved for different levels of uncertainties, and also for the deterministic case. The results are different and this show the importance of the stochastic modeling
44
Pade, Jan Philipp. "Synchrony and bifurcations in coupled dynamical systems and effects of time delay". Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät, 2015. http://dx.doi.org/10.18452/17293.
Testo completoAbstract (sommario):
Dynamik auf Netzwerken ist ein mathematisches Feld, das in den letzten Jahrzehnten schnell gewachsen ist und Anwendungen in zahlreichen Disziplinen wie z.B. Physik, Biologie und Soziologie findet. Die Funktion vieler Netzwerke hängt von der Fähigkeit ab, die Elemente des Netzwerkes zu synchronisieren. Mit anderen Worten, die Existenz und die transversale Stabilität der synchronen Mannigfaltigkeit sind zentrale Eigenschaften. Erst seit einigen Jahren wird versucht, den verwickelten Zusammenhang zwischen der Kopplungsstruktur und den Stabilitätseigenschaften synchroner Zustände zu verstehen. Genau das ist das zentrale Thema dieser Arbeit. Zunächst präsentiere ich erste Ergebnisse zur Klassifizierung der Kanten eines gerichteten Netzwerks bezüglich ihrer Bedeutung für die Stabilität des synchronen Zustands. Folgend untersuche ich ein komplexes Verzweigungsszenario in einem gerichteten Ring von Stuart-Landau Oszillatoren und zeige, dass das Szenario persistent ist, wenn dem Netzwerk eine schwach gewichtete Kante hinzugefügt wird. Daraufhin untersuche ich synchrone Zustände in Ringen von Phasenoszillatoren die mit Zeitverzögerung gekoppelt sind. Ich bespreche die Koexistenz synchroner Lösungen und analysiere deren Stabilität und Verzweigungen. Weiter zeige ich, dass eine Zeitverschiebung genutzt werden kann, um Muster im Ring zu speichern und wiederzuerkennen. Diese Zeitverschiebung untersuche ich daraufhin für beliebige Kopplungsstrukturen. Ich zeige, dass invariante Mannigfaltigkeiten des Flusses sowie ihre Stabilität unter der Zeitverschiebung erhalten bleiben. Darüber hinaus bestimme ich die minimale Anzahl von Zeitverzögerungen, die gebraucht werden, um das System äquivalent zu beschreiben. Schließlich untersuche ich das auffällige Phänomen eines nichtstetigen Übergangs zu Synchronizität in Klassen großer Zufallsnetzwerke indem ich einen kürzlich eingeführten Zugang zur Beschreibung großer Zufallsnetzwerke auf den Fall zeitverzögerter Kopplungen verallgemeinere.Since a couple of decades, dynamics on networks is a rapidly growing branch of mathematics with applications in various disciplines such as physics, biology or sociology. The functioning of many networks heavily relies on the ability to synchronize the network’s nodes. More precisely, the existence and the transverse stability of the synchronous manifold are essential properties. It was only in the last few years that people tried to understand the entangled relation between the coupling structure of a network, given by a (di-)graph, and the stability properties of synchronous states. This is the central theme of this dissertation. I first present results towards a classification of the links in a directed, diffusive network according to their impact on the stability of synchronization. Then I investigate a complex bifurcation scenario observed in a directed ring of Stuart-Landau oscillators. I show that under the addition of a single weak link, this scenario is persistent. Subsequently, I investigate synchronous patterns in a directed ring of phase oscillators coupled with time delay. I discuss the coexistence of multiple of synchronous solutions and investigate their stability and bifurcations. I apply these results by showing that a certain time-shift transformation can be used in order to employ the ring as a pattern recognition device. Next, I investigate the same time-shift transformation for arbitrary coupling structures in a very general setting. I show that invariant manifolds of the flow together with their stability properties are conserved under the time-shift transformation. Furthermore, I determine the minimal number of delays needed to equivalently describe the system’s dynamics. Finally, I investigate a peculiar phenomenon of non-continuous transition to synchrony observed in certain classes of large random networks, generalizing a recently introduced approach for the description of large random networks to the case of delayed couplings.
45
Swanepoel, Pieter Frederick Renier. "Dynamic compensation for performance characteristic differences of wind generator coupled pumps". Thesis, Port Elizabeth Technikon, 2000. http://hdl.handle.net/10948/25.
Testo completoAbstract (sommario):
The lack of services such as electricity in the rural areas of South Africa has given rise to the use of pump water and the windmills. The ones in use currently are maintenance intensive. There is a corrosive element in water and this sometimes requires plastic or other non-corrosive materials to be used for pump components and pipes. Solar panels are expensive and have low efficiencies. Alternative energy systems such as diesel engine driven- mono pumps or -turbines or windmills are costly, which means that the overall efficiency must be maximized to reduce these costs.
46
Chaker, Driss. "Effect of building height on dynamic inelastic response of coupled walls". Thesis, University of Ottawa (Canada), 1990. http://hdl.handle.net/10393/5653.
Testo completoAbstract (sommario):
Coupled wall structures when subjected to earthquakes possess both strength and deformation capacity beyond the elastic range. Although coupled wall systems have a long history of satisfactory use in stiffening multistory buildings, there is a need for information on the behavior of such structures under strong earthquake motions. Inelastic dynamic analysis was carried out in this research project to develop charts that show variation in ductility requirement with structure height when other structural and ground motion parameters are kept constant. Three structures with different building height, and the same overall geometry were selected for analysis. A total of 20 coupled wall structures were analyzed in this investigation. Each structure was analyzed with different levels of yield strength and two different levels of beam-to-wall strength ratio. The objective of the current study is to establish a relationship between height, strength and ductility requirement. An effort was made to express maximum wall and beam ductility requirement analytically for the coupled wall structures considered in this investigation.
47
So, Richard Hau Yue. "Optimising the response of head-coupled systems to dynamic head movements". Thesis, University of Southampton, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.261967.
Testo completo
48
Meng, Jiulong. "Coupled wave propagation in a rod with a dynamic absorber layer". Thesis, Massachusetts Institute of Technology, 1991. http://hdl.handle.net/1721.1/38719.
Testo completo
49
Martone, Giovanni Italo. "Static and dynamic properties of spin-orbit-coupled Bose-Einstein condensates". Doctoral thesis, Università degli studi di Trento, 2014. https://hdl.handle.net/11572/367751.
Testo completoAbstract (sommario):
The recent realization of synthetic spin-orbit coupling represents an outstanding achievement in the physics of ultracold quantum gases. In this thesis we explore the properties of spin-orbit-coupled Bose-Einstein condensates with equal Rashba and Dresselhaus strengths. These systems present a rich phase diagram, which exhibits a tricritical point separating a single-minimum phase, a spin-polarized plane-wave phase, and a stripe phase. In the stripe phase translational invariance is spontaneously broken, in analogy with supersolids. Spin-orbit coupling also strongly affects the dynamics of the system. In particular, the excitation spectrum exhibits intriguing features, including the suppression of the sound velocity, the emergence of a roton minimum in the plane-wave phase, and the appearance of a double gapless band structure in the stripe phase. Finally, we discuss a combined procedure to make the stripes visible and stable, thus allowing for a direct experimental detection.
50
Martone, Giovanni Italo. "Static and dynamic properties of spin-orbit-coupled Bose-Einstein condensates". Doctoral thesis, University of Trento, 2014. http://eprints-phd.biblio.unitn.it/1365/1/Martone_thesis.pdf.
Testo completoAbstract (sommario):
The recent realization of synthetic spin-orbit coupling represents an outstanding achievement in the physics of ultracold quantum gases. In this thesis we explore the properties of spin-orbit-coupled Bose-Einstein condensates with equal Rashba and Dresselhaus strengths. These systems present a rich phase diagram, which exhibits a tricritical point separating a single-minimum phase, a spin-polarized plane-wave phase, and a stripe phase. In the stripe phase translational invariance is spontaneously broken, in analogy with supersolids. Spin-orbit coupling also strongly affects the dynamics of the system. In particular, the excitation spectrum exhibits intriguing features, including the suppression of the sound velocity, the emergence of a roton minimum in the plane-wave phase, and the appearance of a double gapless band structure in the stripe phase. Finally, we discuss a combined procedure to make the stripes visible and stable, thus allowing for a direct experimental detection.