Dissertations / Theses: 'Complex Dynamic Systems Theory'

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Beach, Joni Leigh. "A Grounded Theory Study of Systems Theory and Clothing and Textiles Theories for the Development of a Dynamic, Complex Human Systems Theory." Diss., Virginia Tech, 1999. http://hdl.handle.net/10919/29373.

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Metatheory, a study of theories, was the focus of this research study. A qualitative, grounded theory research design was used to examine documents on systems theory found outside the field of Clothing and Textiles (CT) and the social psychological theories used within CT. Recognizing the dynamic, complex nature of the human system and its interaction with multiple other systems led to the question of: What multidimensional theoretical framework would address this complexity and provide an expanded view for research and education in the field of CT? Data were collected from documentary materials pertaining to systems theory and CT theories by the researcher in a library search of the literature. Four domains were identified from the data that were collected and analyzed. The domains were Relationship, Process, Organization, and Outcomes. Then, a holistic, systemic theoretical framework and the Human-Environment Systems model were developed from the integration of systems theory and the CT theories. The model was designed to give a general, abstract visual representation of the theoretical concepts of a holistic, systemic view of the human-environment unit. A discussion of the complex societal issue of body image and eating disorders in females served to illustrate the use of the proposed theoretical framework and model. Recommendations were made for future exploration of the use of a holistic perspective for research and educational practices in the field of CT in order to address dynamic, complex human-environment problems.
Ph. D.

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Chetty, Vasu Nephi. "Theory and Applications of Network Structure of Complex Dynamical Systems." BYU ScholarsArchive, 2017. https://scholarsarchive.byu.edu/etd/6270.

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One of the most powerful properties of mathematical systems theory is the fact that interconnecting systems yields composites that are themselves systems. This property allows for the engineering of complex systems by aggregating simpler systems into intricate patterns. We call these interconnection patterns the "structure" of the system. Similarly, this property also enables the understanding of complex systems by decomposing them into simpler parts. We likewise call the relationship between these parts the "structure" of the system. At first glance, these may appear to represent identical views of structure of a system. However, further investigation invites the question: are these two notions of structure of a system the same? This dissertation answers this question by developing a theory of dynamical structure. The work begins be distinguishing notions of structure from their associated mathematical representations, or models, of a system. Focusing on linear time invariant (LTI) systems, the key technical contributions begin by extending the definition of the dynamical structure function to all LTI systems and proving essential invariance properties as well as extending necessary and sufficient conditions for the reconstruction of the dynamical structure function from data. Given these extensions, we then develop a framework for analyzing the structures associated with different representations of the same system and use this framework to show that interconnection (or subsystem) structures are not necessarily the same as decomposition (or signal) structures. We also show necessary and sufficient conditions for the reconstruction of the interconnection (or subsystem) structure for a class of systems. In addition to theoretical contributions, this work also makes key contributions to specific applications. In particular, network reconstruction algorithms are developed that extend the applicability of existing methods to general LTI systems while improving the computational complexity. Also, a passive reconstruction method was developed that enables reconstruction without actively probing the system. Finally, the structural theory developed here is used to analyze the vulnerability of a system to simultaneous attacks (coordinated or uncoordinated), enabling a novel approach to the security of cyber-physical-human systems.

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Davis, Jacqueline Topsy Mengersen. "The role of culture in children's sex-typed preferences for colours, toys, and affordances : a systems theory approach." Thesis, University of Cambridge, 2019. https://www.repository.cam.ac.uk/handle/1810/289913.

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Children's sex-typed preferences for colours and toys are well-established, and often function as markers of sex-typicality in research on the development of sex-typed behaviour. However, children's sex-typed colour and toy preferences have not been tested cross-culturally, or in remote unindustrialised cultural settings. The present thesis tested children's preferences for sex-typed toys in four cultural settings: Shipibo villages in the Lake Imiria region of the Peruvian Amazon; kastom villages in the mountains of Tanna Island in Vanuatu in the South Pacific; children attending school in Lenakel town on Tanna Island; and in a large industrialised city in Australia. It also tested children's colour preferences in three of these cultures. It was hypothesised that colour and toy preferences would show some similarities across cultures, and further, that similarities in toy preferences across cultures would be explained by the different types of play afforded by the toys. Results suggested that colour preferences, specifically, a sex difference in preference for pink, are specific to industrialised cultures. Results further suggested that some sex differences in toy preferences replicate in different cultures, and that the relationship between toy preferences and children's preferences for play affordances is a potentially important area for further research. The present thesis also provided two demonstrations of how new statistical methods, adapted from complex and dynamic systems theory, could be applied to the cross-cultural dataset. A machine learning method suggested that sex, more than culture, affects children's sex-typed toy preferences. A multistate dynamic method further suggested that sex, more than culture, affects the dynamics of children's toy choices.

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Krishan, Kapilanjan. "Characterizations of spatio-temporal complex systems." Diss., Available online, Georgia Institute of Technology, 2005, 2005. http://etd.gatech.edu/theses/available/etd-05162005-071906/.

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Thesis (Ph. D.)--Physics, Georgia Institute of Technology, 2006.
Schatz, Michael, Committee Chair ; Cvitanovic, Predrag, Committee Member ; Uzer, Turgay, Committee Member ; Grigoriev, Roman, Committee Member ; Mischaikow, Konstantin, Committee Member.

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Siddique, Shahnewaz. "Failure mechanisms of complex systems." Diss., Georgia Institute of Technology, 2014. http://hdl.handle.net/1853/51831.

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Understanding the behavior of complex, large-scale, interconnected systems in a rigorous and structured manner is one of the most pressing scientific and technological challenges of current times. These systems include, among many others, transportation and communications systems, smart grids and power grids, financial markets etc. Failures of these systems have potentially enormous social, environmental and financial costs. In this work, we investigate the failure mechanisms of load-sharing complex systems. The systems are composed of multiple nodes or components whose failures are determined based on the interaction of their respective strengths and loads (or capacity and demand respectively) as well as the ability of a component to share its load with its neighbors when needed. Each component possesses a specific strength (capacity) and can be in one of three states: failed, damaged or functioning normally. The states are determined based on the load (demand) on the component. We focus on two distinct mechanisms to model the interaction between components strengths and loads. The first, a Loss of Strength (LOS) model and the second, a Customer Service (CS) model. We implement both models on lattice and scale-free graph network topologies. The failure mechanisms of these two models demonstrate temporal scaling phenomena, phase transitions and multiple distinct failure modes excited by extremal dynamics. We find that the resiliency of these models is sensitive to the underlying network topology. For critical ranges of parameters the models demonstrate power law and exponential failure patterns. We find that the failure mechanisms of these models have parallels to failure mechanisms of critical infrastructure systems such as congestion in transportation networks, cascading failure in electrical power grids, creep-rupture in composite structures, and draw-downs in financial markets. Based on the different variants of failure, strategies for mitigating and postponing failure in these critical infrastructure systems can be formulated.

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Glazier, Paul S. "Applications of dynamical systems theory and 'complex' analyses to cricket fast bowling." Thesis, Sheffield Hallam University, 2011. http://shura.shu.ac.uk/20686/.

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The aims of this thesis were to: (i) increase understanding of the biomechanical and motor control processes that underpin proficient fast bowling performance using dynamical systems theory and 'complex' analyses; and (ii) demonstrate the application of dynamical systems theory and the utility of 'complex' analyses to performance-oriented sports biomechanics research using cricket fast bowling as a representative task vehicle. Prior to analysing within- and between-bowler differences in coordination patterns at different levels of analysis and their relationship to ball release speed, the suitability of manual coordinate digitising for analysing intra- and inter-individual variability was examined. Both the reliability of time-discrete and time-continuous kinematic variables was considered. Of the 33 time-discrete kinematic variables examined, 31 exhibited between-participant variances and re-digitisation variances that accounted for the largest and smallest portions of total variance, respectively. Furthermore, re-digitisation variance accounted for less than 5% of total variance in 29 of these variables with 15 of these exhibiting less than 1%. For the 45 time-continuous kinematic variables, measurement error accounted for 17.2% of movement variability (range 4.3-41.0%). When considered together, these results indicated that manual coordinate digitising was sufficiently sensitive to reliably measure differences in technique within and between bowlers. Kohonen Self-Organising Maps (SOMs) were used to analyse coordination patterns in cricket fast bowling at a global whole-body level of analysis. Qualitative differences in SOM trajectories between bowlers signified participant-specific coordination patterns, which were attributed to differences in organismic constraints and intrinsic dynamics. A theoretical argument against the common optimal movement pattern concept was constructed and the utility of SOMs was evaluated. Several issues currently limiting their practical application, including the difficulty in linking the SOM trajectory to aspects of technique and the inability of biomechanists to identify optimal sports techniques, were highlighted. A combination of 'complex' analytical techniques was then applied to quantify intersegmental coordination among key limb and torso segments. Cross-correlation functions showed that moderate (0.5+) to very strong (0.9+) coupling relationships existed for the four segment couplings (NBA vs. FL, BA vs. NBA, BA vs. FL, UT vs.P) with the majority of these moving in synchrony. Statistically significant mean differences in both cross-correlation coefficients and average coupling angle for the four segment couplings throughout (0-100%), and during different phases (0-24%, 25-49%, 50-74%, 75-99%) of, the delivery stride provided further evidence of participant-specific coordination patterns. However, no associations between coupling relationships and ball release speed could be identified either within or between bowlers. This study further highlighted the difficulties in making associations between technique and outcomes.It was concluded that, based on the reported research findings, dynamical systems theory and its associated 'complex' analyses could make a substantive contribution to the enhancement of knowledge of cricket fast bowling techniques and also advance applied sports biomechanics research more generally. Further investigations into cricket fast bowling performance, focusing on the link between technique and outcomes using a combination of kinetic, energetic and coordination analyses, were identified as a research priority.

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Zhang, Daili. "Multi-agent based control of large-scale complex systems employing distributed dynamic inference engine." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/33963.

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Increasing societal demand for automation has led to considerable efforts to control large-scale complex systems, especially in the area of autonomous intelligent control methods. The control system of a large-scale complex system needs to satisfy four system level requirements: robustness, flexibility, reusability, and scalability. Corresponding to the four system level requirements, there arise four major challenges. First, it is difficult to get accurate and complete information. Second, the system may be physically highly distributed. Third, the system evolves very quickly. Fourth, emergent global behaviors of the system can be caused by small disturbances at the component level. The Multi-Agent Based Control (MABC) method as an implementation of distributed intelligent control has been the focus of research since the 1970s, in an effort to solve the above-mentioned problems in controlling large-scale complex systems. However, to the author's best knowledge, all MABC systems for large-scale complex systems with significant uncertainties are problem-specific and thus difficult to extend to other domains or larger systems. This situation is partly due to the control architecture of multiple agents being determined by agent to agent coupling and interaction mechanisms. Therefore, the research objective of this dissertation is to develop a comprehensive, generalized framework for the control system design of general large-scale complex systems with significant uncertainties, with the focus on distributed control architecture design and distributed inference engine design. A Hybrid Multi-Agent Based Control (HyMABC) architecture is proposed by combining hierarchical control architecture and module control architecture with logical replication rings. First, it decomposes a complex system hierarchically; second, it combines the components in the same level as a module, and then designs common interfaces for all of the components in the same module; third, replications are made for critical agents and are organized into logical rings. This architecture maintains clear guidelines for complexity decomposition and also increases the robustness of the whole system. Multiple Sectioned Dynamic Bayesian Networks (MSDBNs) as a distributed dynamic probabilistic inference engine, can be embedded into the control architecture to handle uncertainties of general large-scale complex systems. MSDBNs decomposes a large knowledge-based system into many agents. Each agent holds its partial perspective of a large problem domain by representing its knowledge as a Dynamic Bayesian Network (DBN). Each agent accesses local evidence from its corresponding local sensors and communicates with other agents through finite message passing. If the distributed agents can be organized into a tree structure, satisfying the running intersection property and d-sep set requirements, globally consistent inferences are achievable in a distributed way. By using different frequencies for local DBN agent belief updating and global system belief updating, it balances the communication cost with the global consistency of inferences. In this dissertation, a fully factorized Boyen-Koller (BK) approximation algorithm is used for local DBN agent belief updating, and the static Junction Forest Linkage Tree (JFLT) algorithm is used for global system belief updating. MSDBNs assume a static structure and a stable communication network for the whole system. However, for a real system, sub-Bayesian networks as nodes could be lost, and the communication network could be shut down due to partial damage in the system. Therefore, on-line and automatic MSDBNs structure formation is necessary for making robust state estimations and increasing survivability of the whole system. A Distributed Spanning Tree Optimization (DSTO) algorithm, a Distributed D-Sep Set Satisfaction (DDSSS) algorithm, and a Distributed Running Intersection Satisfaction (DRIS) algorithm are proposed in this dissertation. Combining these three distributed algorithms and a Distributed Belief Propagation (DBP) algorithm in MSDBNs makes state estimations robust to partial damage in the whole system. Combining the distributed control architecture design and the distributed inference engine design leads to a process of control system design for a general large-scale complex system. As applications of the proposed methodology, the control system design of a simplified ship chilled water system and a notional ship chilled water system have been demonstrated step by step. Simulation results not only show that the proposed methodology gives a clear guideline for control system design for general large-scale complex systems with dynamic and uncertain environment, but also indicate that the combination of MSDBNs and HyMABC can provide excellent performance for controlling general large-scale complex systems.

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Penkovsky, Bogdan. "Theory and modeling of complex nonlinear delay dynamics applied to neuromorphic computing." Thesis, Bourgogne Franche-Comté, 2017. http://www.theses.fr/2017UBFCD059/document.

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Cette thèse développe une nouvelle approche pour la conception d'un reservoir computer, l'un des défis de la science et de la technologie modernes. La thèse se compose de deux parties, toutes deux s'appuyant sur l'analogie entre les systèmes optoelectroniques à retard et les dynamiques spatio-temporelles non linéaires. Dans la première partie (Chapitres 1 et 2) cette analogie est utilisée dans une perspective fondamentale afin d'étudier les formes auto-organisées connues sous le nom d'états Chimère, mis en évidence une première fois comme une conséquence de ces travaux. Dans la deuxième partie (Chapitres 3 et 4) la même analogie est exploitée dans une perspective appliquée afin de concevoir et mettre en oeuvre un concept de traitement de l'information inspiré par le cerveau: un réservoir computer fonctionnant en temps réel est construit dans une puce FPGA, grâce à la mise en oeuvre d'une dynamique à retard et de ses couches d'entrée et de sortie, pour obtenir un système traitement d'information autonome intelligent
The thesis develops a novel approach to design of a reservoir computer, one of the challenges of modern Science and Technology. It consists of two parts, both connected by the correspondence between optoelectronic delayed-feedback systems and spatio-temporal nonlinear dynamics. In the first part (Chapters 1 and 2), this correspondence is used in a fundamental perspective, studying self-organized patterns known as chimera states, discovered for the first time in purely temporal systems. Study of chimera states may shed light on mechanisms occurring in many structurally similar high-dimensional systems such as neural systems or power grids. In the second part (Chapters 3 and 4), the same spatio-temporal analogy is exploited from an applied perspective, designing and implementing a brain-inspired information processing device: a real-time digital reservoir computer is constructed in FPGA hardware. The implementation utilizes delay dynamics and realizes input as well as output layers for an autonomous cognitive computing system

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Ladd, Dana Forrest. "Extending Two-Dimensional Knowledge Management System Theory with Organizational Activity Systems' Workflow Dynamics." ScholarWorks, 2016. https://scholarworks.waldenu.edu/dissertations/3305.

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Between 2005 and 2010 and across 48 countries, including the United States, an increasing positive correlation emerged between national intellectual capital and gross domestic product per capita. The problem remains organizations operating with increasingly complex knowledge networks often lose intellectual capital resulting from ineffective knowledge management practices. The purpose of this study was to provide management opportunities to reduce intellectual capital loss. The first research question addressed how an enhanced intelligent, complex, and adaptive system (ICAS) model could clarify management's understanding of organizational knowledge transfer. The second research question addressed how interdisciplinary theory could become more meaningfully infused to enhance management practices of the organization's knowledge ecosystem. The nature of this study was phenomenological to gain deeper understanding of individual experiences related to knowledge flow phenomena. Data were collected from a single historical research dataset containing 11 subject interviews and analyzed using Moustakas' heuristic framework. Original interviews were collected in 2012 during research within a military unit, included in this study based on theme alignment. Organizational, knowledge management, emergent systems, and cognition theories were synthesized to enhance understandings of emergent ICAS forces. Individuals create unique ICAS flow emergent force dynamics in relation to micro- and macro-meso sensemaking and sensegiving. Findings indicated individual knowledge work significantly shapes emergent ICAS flow dynamics. Collectively enhancing knowledge stewardship over time could foster positive social change by improving national welfare.

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Passey, Jr David Joseph. "Growing Complex Networks for Better Learning of Chaotic Dynamical Systems." BYU ScholarsArchive, 2020. https://scholarsarchive.byu.edu/etd/8146.

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This thesis advances the theory of network specialization by characterizing the effect of network specialization on the eigenvectors of a network. We prove and provide explicit formulas for the eigenvectors of specialized graphs based on the eigenvectors of their parent graphs. The second portion of this thesis applies network specialization to learning problems. Our work focuses on training reservoir computers to mimic the Lorentz equations. We experiment with random graph, preferential attachment and small world topologies and demonstrate that the random removal of directed edges increases predictive capability of a reservoir topology. We then create a new network model by growing networks via targeted application of the specialization model. This is accomplished iteratively by selecting top preforming nodes within the reservoir computer and specializing them. Our generated topology out-preforms all other topologies on average.

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Nebel, Anne Louise. "Emerging from the task : a complex dynamic systems theory investigation of English L2 learner- writing task engagement and the phenomenon of complexity." Thesis, Lancaster University, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.658215.

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A number of studies of interest to TBL T and SLA researchers have examined L2 task complexity in pedagogical and assessment contexts by using models of cognitive complexity to predict and account for complexity in learner performances as responses to tasks (e.g. Chalhoub-Deville, 2001; Elder, Iwashita & McNamara, 2002; Robinson, 2001, 2005; Skehan & Foster, 1999,2001; Wigglesworth, 2001). These experimental studies manipulated task variables in order to identify how those variables impact complexity-as determined by quantitative measures of fluency, accuracy and complexity-in the resulting performances. The findings have varied considerably, both within and across studies, however, drawing their underlying assumptions into critical view and creating an opportunity for other theories and methods in applied linguistics to bring new light to the phenomenon of complexity. Complex dynamic systems theory provides a useful framework for better understanding complexity in this applied linguistics problem space (Larsen-Freeman & Cameron, 2008).

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MacKenzie, Tony. "Create accurate numerical models of complex spatio-temporal dynamical systems with holistic discretisation." University of Southern Queensland, Faculty of Sciences, 2005. http://eprints.usq.edu.au/archive/00001466/.

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This dissertation focuses on the further development of creating accurate numerical models of complex dynamical systems using the holistic discretisation technique [Roberts, Appl. Num. Model., 37:371-396, 2001]. I extend the application from second to fourth order systems and from only one spatial dimension in all previous work to two dimensions (2D). We see that the holistic technique provides useful and accurate numerical discretisations on coarse grids. We explore techniques to model the evolution of spatial patterns governed by pdes such as the Kuramoto-Sivashinsky equation and the real-valued Ginzburg-Landau equation. We aim towards the simulation of fluid flow and convection in three spatial dimensions. I show that significant steps have been taken in this dissertation towards achieving this aim. Holistic discretisation is based upon centre manifold theory [Carr, Applications of centre manifold theory, 1981] so we are assured that the numerical discretisation accurately models the dynamical system and may be constructed systematically. To apply centre manifold theory the domain is divided into elements and using a homotopy in the coupling parameter, subgrid scale fields are constructed consisting of actual solutions of the governing partial differential equation(pde). These subgrid scale fields interact through the introduction of artificial internal boundary conditions. View the centre manifold (macroscale) as the union of all states of the collection of subgrid fields (microscale) over the physical domain. Here we explore how to extend holistic discretisation to the fourth order Kuramoto-Sivashinsky pde. I show that the holistic models give impressive accuracy for reproducing the steady states and time dependent phenomena of the Kuramoto-Sivashinsky equation on coarse grids. The holistic method based on local dynamics compares favourably to the global methods of approximate inertial manifolds. The excellent performance of the holistic models shown here is strong evidence in support of the holistic discretisation technique. For shear dispersion in a 2D channel a one-dimensional numerical approximation is generated directly from the two-dimensional advection-diffusion dynamics. We find that a low order holistic model contains the shear dispersion term of the Taylor model [Taylor, IMA J. Appl. Math., 225:473-477, 1954]. This new approach does not require the assumption of large x scales, formerly absolutely crucial in deriving the Taylor model. I develop holistic discretisation for two spatial dimensions by applying the technique to the real-valued Ginzburg-Landau equation as a representative example of second order pdes. The techniques will apply quite generally to second order reaction-diffusion equations in 2D. This is the first study implementing holistic discretisation in more than one spatial dimension. The previous applications of holistic discretisation have developed algebraic forms of the subgrid field and its evolution. I develop an algorithm for numerical construction of the subgrid field and its evolution for 1D and 2D pdes and explore various alternatives. This new development greatly extends the class of problems that may be discretised by the holistic technique. This is a vital step for the application of the holistic technique to higher spatial dimensions and towards discretising the Navier-Stokes equations.

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Alharbi, Fahad. "The Dynamics of the L2 Motivational Self System among Saudi Study Abroad Students." Scholar Commons, 2017. http://scholarcommons.usf.edu/etd/6672.

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Adult second language acquisition takes time over an extended period of time during which the L2 motivation of learners goes through periods of ups and downs. Dörnyei, MacIntyre and Henry (2015) recognized the inherently dynamic nature of L2 motivation and called for adopting the Complex Dynamic System Theory (CDST) when studying this phenomenon. While using a CDST perspective, this mixed method study drew on Dörnyei’s (2009b) model of the Motivational Self System to examine the L2 motivation of 86 Saudi study-abroad students. Also, the construct of the Anti-ought to Self (Thompson, 2015) and aspects of the Appraisal Theory (Schumann, 2001) were adopted to guide this examination. The results of the study showed that the L2 motivation of the participants fell into four main motivational patterns. Also, some of the participants shifted into new attractor states over the course of their academic semester. Another important finding was that the Anti-ought to Self appeared as an important construct. The results of the standard multiple regressions showed that the amount of the variance in the Intended Learning Effort that was accounted for by the Anti-ought to Self alone exceeded the amount of the variance accounted for by the other explanatory variables put together. Also, the analysis of the quantitative and qualitative data showed that the use of the Appraisal Theory improved the construct validity of the Learning Experiences. The implications of these findings and future directions of the L2 motivational research were also discussed in the study.

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Molter, Colin. "Storing information through complex dynamics in recurrent neural networks." Doctoral thesis, Universite Libre de Bruxelles, 2005. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/211039.

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The neural net computer simulations which will be presented here are based on the acceptance of a set of assumptions that for the last twenty years have been expressed in the fields of information processing, neurophysiology and cognitive sciences. First of all, neural networks and their dynamical behaviors in terms of attractors is the natural way adopted by the brain to encode information. Any information item to be stored in the neural net should be coded in some way or another in one of the dynamical attractors of the brain and retrieved by stimulating the net so as to trap its dynamics in the desired item's basin of attraction. The second view shared by neural net researchers is to base the learning of the synaptic matrix on a local Hebbian mechanism. The last assumption is the presence of chaos and the benefit gained by its presence. Chaos, although very simply produced, inherently possesses an infinite amount of cyclic regimes that can be exploited for coding information. Moreover, the network randomly wanders around these unstable regimes in a spontaneous way, thus rapidly proposing alternative responses to external stimuli and being able to easily switch from one of these potential attractors to another in response to any coming stimulus.

In this thesis, it is shown experimentally that the more information is to be stored in robust cyclic attractors, the more chaos appears as a regime in the back, erratically itinerating among brief appearances of these attractors. Chaos does not appear to be the cause but the consequence of the learning. However, it appears as an helpful consequence that widens the net's encoding capacity. To learn the information to be stored, an unsupervised Hebbian learning algorithm is introduced. By leaving the semantics of the attractors to be associated with the feeding data unprescribed, promising results have been obtained in term of storing capacity.
Doctorat en sciences appliquées
info:eu-repo/semantics/nonPublished

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Barbaresi, Mattia. "Computational mechanics: from theory to practice." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2018. http://amslaurea.unibo.it/15649/.

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In the last fifty years, computational mechanics has gained the attention of a large number of disciplines, ranging from physics and mathematics to biology, involving all the disciplines that deal with complex systems or processes. With ϵ-machines, computational mechanics provides powerful models that can help characterizing these systems. To date, an increasing number of studies concern the use of such methodologies; nevertheless, an attempt to make this approach more accessible in practice is lacking yet. Starting from this point, this thesis aims at investigating a more practical approach to computational mechanics so as to make it suitable for applications in a wide spectrum of domains. ϵ-machines are analyzed more in the robotics scene, trying to understand if they can be exploited in contexts with typically complex dynamics like swarms. Experiments are conducted with random walk behavior and the aggregation task. Statistical complexity is first studied and tested on the logistical map and then exploited, as a more applicative case, in the analysis of electroencephalograms as a classification parameter, resulting in the discrimination between patients (with different sleep disorders) and healthy subjects. The number of applications that may benefit from the use of such a technique is enormous. Hopefully, this work has broadened the prospect towards a more applicative interest.

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Schwartz, Daniel H. "Exploring Team Dynamics: The Evolution of Coordination in a Complex Command and Control Environment." Wright State University / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=wright1229430203.

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Li, Yao. "Stochastic perturbation theory and its application to complex biological networks -- a quantification of systematic features of biological networks." Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/49013.

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The primary objective of this thesis is to make a quantitative study of complex biological networks. Our fundamental motivation is to obtain the statistical dependency between modules by injecting external noise. To accomplish this, a deep study of stochastic dynamical systems would be essential. The first chapter is about the stochastic dynamical system theory. The classical estimation of invariant measures of Fokker-Planck equations is improved by the level set method. Further, we develop a discrete Fokker-Planck-type equation to study the discrete stochastic dynamical systems. In the second part, we quantify systematic measures including degeneracy, complexity and robustness. We also provide a series of results on their properties and the connection between them. Then we apply our theory to the JAK-STAT signaling pathway network.

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Runge, Jakob. "Detecting and quantifying causality from time series of complex systems." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät, 2014. http://dx.doi.org/10.18452/17017.

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Der technologische Fortschritt hat in jüngster Zeit zu einer großen Zahl von Zeitreihenmessdaten über komplexe dynamische Systeme wie das Klimasystem, das Gehirn oder das globale ökonomische System geführt. Beispielsweise treten im Klimasystem Prozesse wie El Nino-Southern Oscillation (ENSO) mit dem indischen Monsun auf komplexe Art und Weise durch Telekonnektionen und Rückkopplungen in Wechselwirkung miteinander. Die Analyse der Messdaten zur Rekonstruktion der diesen Wechselwirkungen zugrunde liegenden kausalen Mechanismen ist eine Möglichkeit komplexe Systeme zu verstehen, insbesondere angesichts der unendlich-dimensionalen Komplexität der physikalischen Prozesse. Diese Dissertation verfolgt zwei Hauptfragen: (i) Wie können, ausgehend von multivariaten Zeitreihen, kausale Wechselwirkungen praktisch detektiert werden? (ii) Wie kann die Stärke kausaler Wechselwirkungen zwischen mehreren Prozessen in klar interpretierbarer Weise quantifiziert werden? Im ersten Teil der Arbeit werden die Theorie zur Detektion und Quantifikation nichtlinearer kausaler Wechselwirkungen (weiter-)entwickelt und wichtige Aspekte der Schätztheorie untersucht. Zur Quantifikation kausaler Wechselwirkungen wird ein physikalisch motivierter, informationstheoretischer Ansatz vorgeschlagen, umfangreich numerisch untersucht und durch analytische Resultate untermauert. Im zweiten Teil der Arbeit werden die entwickelten Methoden angewandt, um Hypothesen über kausale Wechselwirkungen in Klimadaten der vergangenen hundert Jahre zu testen und zu generieren. In einem zweiten, eher explorativen Schritt wird ein globaler Luftdruck-Datensatz analysiert, um wichtige treibende Prozesse in der Atmosphäre zu identifizieren. Abschließend wird aufgezeigt, wie die Quantifizierung von Wechselwirkungen Aufschluss über mögliche qualitative Veränderungen in der Klimadynamik (Kipppunkte) geben kann und wie kausal treibende Prozesse zur optimalen Vorhersage von Zeitreihen genutzt werden können.
Today''s scientific world produces a vastly growing and technology-driven abundance of time series data of such complex dynamical systems as the Earth''s climate, the brain, or the global economy. In the climate system multiple processes (e.g., El Nino-Southern Oscillation (ENSO) or the Indian Monsoon) interact in a complex, intertwined way involving teleconnections and feedback loops. Using the data to reconstruct the causal mechanisms underlying these interactions is one way to better understand such complex systems, especially given the infinite-dimensional complexity of the underlying physical equations. In this thesis, two main research questions are addressed: (i) How can general causal interactions be practically detected from multivariate time series? (ii) How can the strength of causal interactions between multiple processes be quantified in a well-interpretable way? In the first part of this thesis, the theory of detecting and quantifying general (linear and nonlinear) causal interactions is developed alongside with the important practical issues of estimation. To quantify causal interactions, a physically motivated, information-theoretic formalism is introduced. The formalism is extensively tested numerically and substantiated by rigorous mathematical results. In the second part of this thesis, the novel methods are applied to test and generate hypotheses on causal interactions in climate time series covering the 20th century up to the present. The results yield insights on an understanding of the Walker circulation and teleconnections of the ENSO system, for example with the Indian Monsoon. Further, in an exploratory way, a global surface pressure dataset is analyzed to identify key processes that drive and govern interactions in the global atmosphere. Finally, it is shown how quantifying interactions can be used to determine possible structural changes, termed tipping points, and as optimal predictors, here applied to the prediction of ENSO.

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Marques, Pedro Jorge da Silva. "A metÃfora e a metonÃmia sob a perspectiva dos sistemas dinÃmicos complexos e da teoria fractal no processo de conceitualizaÃÃo da violÃncia urbana na cidade de Fortaleza-CE." Universidade Federal do CearÃ, 2014. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=11786.

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FundaÃÃo de Amparo Ã Pesquisa do Estado do CearÃ
A metÃfora sempre ocupou um lugar de destaque nos estudos do significado e, com o avanÃo das pesquisas em LinguÃstica Cognitiva, essa figura apresenta-se mais evidente quando posta em relaÃÃo com a metonÃmia, que ganha pouco destaque nas pesquisas acadÃmicas. Nesse contexto, a presente pesquisa tem como objetivos: (i) estabelecer a primazia da metonÃmia sobre a metÃfora por meio da anÃlise dinÃmica do discurso dos participantes de grupos focais, ao discutirem a violÃncia urbana na cidade de Fortaleza; (ii) verificar se as relaÃÃes metonÃmicas dÃo-se tanto em nÃvel contextual como de enunciado; e (iii) demonstrar que as metonÃmias sÃo responsÃveis pela emergÃncia de grande parte dos veÃculos metafÃricos, tÃo importantes para a construÃÃo do sentido. Para tanto, fez-se necessÃrio discutir as principais abordagens dos fenÃmenos Ã luz da teoria dos Sistemas DinÃmicos Complexos, ancorados em Larsen-Freeman (1997); Larsen-Freeman e Cameron (2008), na teoria fractal, com fundamentos em Paiva (2010) e Mandelbrot (1982), assim como Capra (2006). Esse referencial teÃrico serviu de base para verificarmos a hipÃtese de que grande parte das metÃforas serÃ oriunda de metonÃmia e de que as relaÃÃes que contribuem para a emergÃncia dessa figura deram-se tanto em nÃvel contextual como de enunciado, surgindo de forma fragmentada no discurso real dos participantes dos grupos focais. AlÃm disso, a pesquisa propÃe-se tambÃm a descrever o processo de conceitualizaÃÃo da violÃncia urbana com base nos critÃrios do paradigma da complexidade, mostrando sua importÃncia para as atuais pesquisas. Para dar consistÃncia Ã nossa discussÃo, embasamo-nos em autores como Goosens (1990, 1995), Barcelona (1997) e Radden (2003) que tambÃm discutem a complexa relaÃÃo entre metÃfora e metonÃmia. Nosso estudo estÃ pautado em uma pesquisa qualitativa e teÃrica, que nos permite refletir acerca da primazia da metonÃmia em relaÃÃo Ã metÃfora, analisando a transcriÃÃo de trÃs grupos focais que discutiram a questÃo da violÃncia urbana na cidade de Fortaleza-CE. A anÃlise permitiu constatar, atÃ o momento que, em alguns casos, no processo de conceitualizaÃÃo da violÃncia urbana, a metÃfora tem procedÃncia na metonÃmia, visto que as relaÃÃes que estruturam a metonÃmia, como parte pelo todo, instituiÃÃo pelos responsÃveis, efeito pela causa, entre outros, permeiam tanto o enunciado como o contexto da discussÃo dos participantes dos grupos focais. Isso nos fez chegar Ã conclusÃo de que uma sÃrie de metÃforas provÃm de metonÃmias o que mostra que, apesar de a metÃfora e a metonÃmia interagirem entre si, em alguns casos, hÃ primazia desta sobre aquela.
The metaphor has always occupied an important place in meaning studies and with the advances on Cognitive Linguistics researches this figure presents itself more evident when put in relation with metonym, which has less importance on academic researches. In this context, this very work aims: (i) establish the primacy of metonym over metaphor by the dynamic discourse analysis of focal group participants when discussing urban violence in the city of Fortaleza; (ii) verify if the metonymic relations appear both in context and wording; and (iii) demonstrate that metonyms are responsible for the emerging of great part of metaphorical vehicles, so important to the construction of meaning. Thus, it was necessary to discuss the main approaches of these phenomena in light of Complex Dynamic Systems theory, anchored on Larsen-Freeman (1997); Larsen-Freeman e Cameron (2008), on fractal theory, based in Paiva (2010) e Mandelbrot (1982), as Capra (2006). This theoretical reference served as base to verify the hypothesis that great part of metaphors emerge from metonyms and that the relations contribute to the emerging of that both contextual and wording levels arise fragmented in the real discourse of focal group participants. Furthermore, the research proposes itself to also describe the process of conceptualization of urban violence based in the criteria of complexity paradigm, showing its importance to the current researches. To give consistency to that discussion we based ourselves in authors such as Goosens (1990, 1995), Barcelona (1997) and Radden (2003), who also discuss the complex relation between metaphor and metonym. Our study is ruled by a qualitative and theoretical research that allows us to reflect about the primacy of metonym over metaphor, analyzing the transcription of three focal groups that discussed the urban violence in the city of Fortaleza. The analysis allowed until this moment the ascertainment that in some cases, in the process of conceptualization, the metaphor arises from metonym, as relations that structure metonym, such as take a tree for a forest, institution for its responsible ones, effect by cause, permeate both wording and context of the discussion of the focal group participants. This made us come to the conclusion that a series of metaphors come from metonyms, what shows that although metaphor and metonym interact themselves, there is a primacy of the second over the first in some cases.

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Russell, Scott Raymond. "Interacting constraints shape emergent decision-making of referees." Thesis, Queensland University of Technology, 2013. https://eprints.qut.edu.au/61021/1/Scott%20Russell%20Thesis.pdf.

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How and why football referees made decisions was investigated. A constructivist grounded theory methodology was undertaken to tap into the experiential knowledge of referees. The participant cohort comprised 7 A-League referees (aged 23 to 35) and 8 local Brisbane league referees (aged 20 to 50), spanning the lowest to highest levels of competition in men’s football in Australia. Results found that referees used ‘four pillars’ to underpin their judgments, these were conceptual notions of: safety, fairness, accuracy and entertainment. A fifth pillar ‘consistency’ referred to the referee’s ‘contextual sensitivity’. Results were explained using an ecological dynamics framework that emphasises the individual-environment scale of analysis. It was concluded that interacting constraints shape emergent decision-making in referees which are nested in task goals.

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Blanc, Jean-luc. "Transmission de l'information et complexité des activités de populations neuronales." Thesis, Aix-Marseille, 2012. http://www.theses.fr/2012AIXM4720/document.

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Dans cette thèse, nous abordons les problèmes de la transmission et du traitement de l'information par les assemblées de neurones, du point de vue de l'approche inter-disciplinaire des systèmes complexes en nous référant principalement aux formalismes de la théorie de l'information et de la théorie des systèmes dynamiques. Dans ce contexte, nous nous focalisons sur les mécanismes de représentation de l'information sensorielle par les activités neuronales à travers le codage neuronal. Nous explorons la structure de ce code, à plusieurs échelles grâce à l'étude de différents signaux électrophysiologiques issus de populations de neurones (signaux unitaires, LFP et EEG). Sur le plan méthodologique, nous avons implémenté différents indices permettant d'extraire objectivement l'information des activités neuronales, mais également d'en caractériser la dynamique sous-jacente à partir de séries temporelles de taille finie (le taux d'entropie). Nous avons également étudié un indicateur peu utilisé (le taux d'information mutuelle), qui permet de quantifier l'auto-organisation et les relations de couplage entre deux systèmes. Grâce à des approches théoriques et numériques, nous analysons les propriétés caractéristiques de ces indices et proposons leur utilisation dans le cadre de l'étude des systèmes neuronaux. Ce travail permet de caractériser la complexité de différentes activités neuronales associées aux dynamiques de transmission de l'information
In this thesis, we address the problem of transmission and information processing by neuronal assemblies, in terms of the interdisciplinary approach of complex systems by referring mainly to the formalisms of information theory and dynamical systems. In this context, we focus on the mechanisms underlying sensory information representation by neuronal activity through neural coding. We explore the structure of this code under several scales through the study of different neuronal population electrophysiological signals (singel unit, LFP and EEG). We have implemented various indices in order to extract objectively information from neural activity, but also to characterize the underlying dynamics from finite size time series (the entropy rate). We also defined a new indicator (the mutual information rate), which quantifies self-organization and relations of coupling between two systems. Using theoretical and numerical approaches, we analyze some characteristic properties of these indices and propose their use in the context of the study of neural systems. This work allows us to characterize the complexity of different neuronal activity associated to information transmission dynamics

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White, Jeffrey. "An Inquiry into Factors of Leadership and Cohesion in Complex Teams." ScholarWorks, 2017. https://scholarworks.waldenu.edu/dissertations/4487.

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The external competitive environments and internal group dynamics of organizations are increasing in complexity resulting in new challenges for organizational leaders to improve performance in underperforming teams. The purpose of this phenomenological study was to address what factors led to high-innovation outcomes in complex adaptive systems using a framework constructed from elements of complexity leadership theory and group dynamics research. An in-depth interviewing approach was used to collect data on the lived experience and meaning the participants attributed to their experiences regarding improved team performance. A total of 21 participants were selected from multiple business settings where their team experienced adaptive tension and improved group cohesion. Their stories were reduced into themes using an inductive process and later analyzed through the lens of complexity leadership theory. The factors that emerged in this study, leveraging tension in the group dynamics enabled through objectivity, roles, alignment, capability, execution, purpose, and work ethic that led to mutual respect, directness, and reliance, offer leaders an effective method for achieving sustained team performance. These factors can be used by organizational leaders to improve team performance and consistency in team outcomes over traditional command and control approaches with a work exchange that benefits individual team members. The findings from this study contribute to social change by improving not only team performance, but also member satisfaction. When leadership is viewed from the perspective of the whole system instead of from the perspective of the individual, the relationships between people emerge as the primary enabling factor for high-innovation outcomes.

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Kashinath, Karthik. "Nonlinear thermoacoustic oscillations of a ducted laminar premixed flame." Thesis, University of Cambridge, 2013. https://www.repository.cam.ac.uk/handle/1810/264291.

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Finding limit cycles and their stability is one of the central problems of nonlinear thermoacoustics. However, a limit cycle is not the only type of self-excited oscillation in a nonlinear system. Nonlinear systems can have quasi-periodic and chaotic oscillations. This thesis examines the different types of oscillation in a numerical model of a ducted premixed flame, the bifurcations that lead to these oscillations and the influence of external forcing on these oscillations. Criteria for the existence and stability of limit cycles in single mode thermoacoustic systems are derived analytically. These criteria, along with the flame describing function, are used to find the types of bifurcation and minimum triggering amplitudes. The choice of model for the velocity perturbation field around the flame is shown to have a strong influence on the types of bifurcation in the system. Therefore, a reduced order model of the velocity perturbation field in a forced laminar premixed flame is obtained from Direct Numerical Simulation. It is shown that the model currently used in the literature precludes subcritical bifurcations and multi-stability. The self-excited thermoacoustic system is simulated in the time domain with many modes in the acoustics and analysed using methods from nonlinear dynamical systems theory. The transitions to the periodic, quasiperiodic and chaotic oscillations are via sub/supercritical Hopf, Neimark-Sacker and period-doubling bifurcations. Routes to chaos are established in this system. It is shown that the single mode system, which gives the same results as a describing function approach, fails to capture the period-$2$, period-$k$, quasi-periodic and chaotic oscillations or the bifurcations and multi-stability seen in the multi-modal case, and underpredicts the amplitude. Instantaneous flame images reveal that the wrinkles on the flame surface and pinch off of flame pockets are regular for periodic oscillations, while they are irregular and have multiple time and length scales for quasi-periodic and chaotic oscillations. Cusp formation, their destruction by flame propagation normal to itself, and pinch-off and rapid burning of pockets of reactants are shown to be responsible for generating a heat release rate that is a highly nonlinear function of the velocity perturbations. It is also shown that for a given acoustic model of the duct, many discretization modes are required to capture the rich dynamics and nonlinear feedback between heat release and acoustics seen in experiments. The influence of external harmonic forcing on self-excited periodic, quasi-periodic and chaotic oscillations are examined. The transition to lock-in, the forcing amplitude required for lock-in and the system response at lock-in are characterized. At certain frequencies, even low-amplitude forcing is sufficient to suppress period-$1$ oscillations to amplitudes that are 90$\%$ lower than that of the unforced state. Therefore, open-loop forcing can be an effective strategy for the suppression of thermoacoustic oscillations. This thesis shows that a ducted premixed flame behaves similarly to low-dimensional chaotic systems and that methods from nonlinear dynamical systems theory are superior to the describing function approach in the frequency domain and time domain analysis currently used in nonlinear thermoacoustics.

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Ingram, David. "Using systems theory to do philosophy : one approach, and some suggested terminology : a thesis submitted in fulfilment of the requirements for the degree of Master of Arts in Philosophy in the University of Canterbury /." Thesis, University of Canterbury. Philosophy and Religious Studies, 2007. http://hdl.handle.net/10092/1022.

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This thesis employs perspectives inspired by General Systems Theory to address issues in philosophy, including moral philosophy and philosophy of mind. I present an overview of a range of ideas from the study of physical systems that may be used to provide a firm physicalist foundation to explorations of some common questions in philosophy. I divide these topics into three categories: the Physical Category, the Relevance Category and the Signal Elements Category. I interpret concepts from General Systems Theory, including information and entropy, in a way that I believe facilitates their incorporation into philosophical discussion. I also explain various points arising from General Systems Theory, such as order and disorder, stability, complexity, and self-organisation, and show how ideas from these areas can be applied to certain philosophical problems. I explain relevance in terms of stability, in order to link these scientific perspectives to questions in moral philosophy. I suggest a possible physical foundation for a theory of morality, which takes the form of a variety of Utilitarianism, intended to balance the competing needs of open systems to manage entropy. Such a theory of morality must be capable of dealing with limitations arising from the physicality of information; I propose game theory as a solution to this problem. This thesis also covers issues connected to the above points regarding the nature of consciousness and communication. In particular, I examine the role of linguistic associations in consciousness; and some related features of language and other non-linear representational schemes.

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Staniczenko, Phillip P. A. "Structure, dynamics, and robustness of ecological networks." Thesis, University of Oxford, 2011. http://ora.ox.ac.uk/objects/uuid:3e7b120c-79b0-46ef-b0da-d589578db212.

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Ecosystems are often made up of interactions between large numbers of species. They are considered complex systems because the behaviour of the system as a whole is not always obvious from the properties of the individual parts. A complex system can be represented by a network: a set of interconnected objects. In the case of ecological networks and food webs, the objects are species and the connections are interactions between species. Many complex systems are dynamic and exhibit intricate time series. Time series analysis has been developed to understand a wide range of natural phenomena. This thesis deals with the structure, dynamics, and robustness of ecological networks, the spatial dynamics of fluctuations in a social system, and the analysis of cardiac time series. Biodiversity on Earth is decreasing largely due to human-induced causes. My work looks at the effect of anthropogenic change on ecological networks. In Chapter Two, I investigate predator adaptation on food-web robustness following species extinctions. I identify a new theoretical category of species that may buffer ecosystems against environmental change. In Chapter Three, I study changes in parasitoid-host (consumer-resource) interaction frequencies between complex and simple environments. I show that the feeding preferences of parasitoid species actively change in response to habitat modification. Ecological networks are embedded in spatially-heterogeneous landscapes. In Chapter Four, I assess the role of geography on population fluctuations in an analogous social system. I demonstrate that fluctuations in the number of venture capital firms registered in cities in the United States of America are consistent with spatial and temporal contagion. Understanding how physiological signals vary through time is of interest to medical practitioners. In Chapter Five, I present a technique for quickly quantifying disorder in high frequency event series. Applying the algorithm to patient cardiac time series provides a rapid way to detect the onset of heart arrhythmia. Increasingly, answers to scientific questions lie at the intersection of traditional disciplines. This thesis applies techniques developed in physics and mathematics to problems in ecology and medicine.

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Arbex, Hassan Costa [UNESP]. "Dinâmica não linear de sistemas de levitação magnética." Universidade Estadual Paulista (UNESP), 2012. http://hdl.handle.net/11449/97025.

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Made available in DSpace on 2014-06-11T19:28:33Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-07-05Bitstream added on 2014-06-13T20:08:53Z : No. of bitstreams: 1 arbex_hc_me_bauru.pdf: 6292419 bytes, checksum: 8c3b08ad3eb377db975bacb303c4ceda (MD5)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
O propósito deste trabalho foi estudar as não linearidades na dinâmica de sistemas mecânicos e eletromecânicos. Entre eles inclui-se um corpo em levitação. As não linearidades levam o movimento da estrutura para o Efeito Sommerfeld. Por este fato, o trabalho do motor fica próximo ou na frequência de ressonância. Quando a estrutura atinge a condição de ressonância, a melhor parte da energia é consumida para gerar vibrações de grande amplitude sem nenhuma mudança sensível na frequência do motor. Neste trabalho, foi verificado o fenômeno para alguns sistemas não ideais inclusive o sistema com levitação magnética, discutindo uma forma de conduzir o sistema à condição de ressonância e evitar o absorvedor de energia que ocorre com o efeito Sommerfeld
This paper studies the nonlinearities in dynamics of mechanics and electro mechanics non ideal systems. One of them is a magnetically levitated body. These nonlinearities lead the motion of the structure to the Sommerfeld Effect. For this reason the motor's near or in resonance frequency. When the structure achieves resonance condition, the best part of the energy is consumed to generate large amplitude vibration, with no sensitive change in the motor frequency. In this paper, is checked whether the phenomenon in some non ideal systems and also, if occurs with magnetic levitation. Will be discussed how to drive the system to ressonance condition and to avoid the energy sink that occurs with the Sommerfeld effect

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Arbex, Hassan Costa. "Dinâmica não linear de sistemas de levitação magnética /." Bauru : [s.n.], 2012. http://hdl.handle.net/11449/97025.

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Orientador: José Manoel Balthazar
Banca: Júlio Cesar Ruiz Claeyssen
Banca: Bento Rodrigues de Pontes Junior
Resumo: O propósito deste trabalho foi estudar as não linearidades na dinâmica de sistemas mecânicos e eletromecânicos. Entre eles inclui-se um corpo em levitação. As não linearidades levam o movimento da estrutura para o Efeito Sommerfeld. Por este fato, o trabalho do motor fica próximo ou na frequência de ressonância. Quando a estrutura atinge a condição de ressonância, a melhor parte da energia é consumida para gerar vibrações de grande amplitude sem nenhuma mudança sensível na frequência do motor. Neste trabalho, foi verificado o fenômeno para alguns sistemas não ideais inclusive o sistema com levitação magnética, discutindo uma forma de conduzir o sistema à condição de ressonância e evitar o "absorvedor de energia" que ocorre com o efeito Sommerfeld
Abstract: This paper studies the nonlinearities in dynamics of mechanics and electro mechanics non ideal systems. One of them is a magnetically levitated body. These nonlinearities lead the motion of the structure to the Sommerfeld Effect. For this reason the motor's near or in resonance frequency. When the structure achieves resonance condition, the best part of the energy is consumed to generate large amplitude vibration, with no sensitive change in the motor frequency. In this paper, is checked whether the phenomenon in some non ideal systems and also, if occurs with magnetic levitation. Will be discussed how to drive the system to ressonance condition and to avoid the "energy sink" that occurs with the Sommerfeld effect
Mestre

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28

Ziadat, Wael. "A meta-analysis study of project and programme management complexity in the oil and gas sector of the Middle East and North Africa region." Thesis, University of Manchester, 2018. https://www.research.manchester.ac.uk/portal/en/theses/a-metaanalysis-study-of-project-and-programme-management-complexity-in-the-oil-and-gas-sector-of-the-middle-east-and-north-africa-region(1fb607f9-b665-4dbd-9f10-9ef5f73d43e9).html.

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Projects and programmes are inherently complex; the interaction of people, systems, processes and data within a dynamic environment creates an intricate network of agents whose behaviour can be unpredictable and unexpected. The management of this complexity is ordinarily concerned with the implementation of tools and techniques to ensure that projects are completed within the desired cost and time, at the agreed level of performance and quality â€“ this is often referred to as the â€ ̃iron triangleâ€TM. However, the impact of a dynamic external environment on the â€ ̃softâ€TM boundaries of the project domain can lead to extreme difficulty in attempting to forecast or predict outcomes and system behaviours. This thesis contends that there is a clear desideratum for a new paradigm in project management practice and research that moves beyond the traditionalist (reductionist) approach to one that embraces, rather than attempts to simplify complexity. The research described in this thesis seeks to uncover the characteristics of complexity, in the context of projects and programmes, in an attempt to uncover if complexity is a factor in the determination of â€ ̃valuableâ€TM outcomes. Subsequently, and through the theoretical lens of complexity theory, this research seeks to highlight the importance of our understanding and treatment of complexity in the execution and management of projects and programmes. The research further seeks to demonstrate how complexity thinking may inform a more sophisticated understanding of how projects, programmes and portfolios delivered successfully (Ziadat, 2017). The context of the research is the oil and gas (O & G) engineering sector in the Middle East and North Africa (MENA) region. A two stage qualitative and quantitative methodology is applied, based on deductive reasoning. The first stage involves the development of a questionnaire and a series of unstructured interviews to gain an understanding of the practical consideration that emerges from the literature review. The second stage of the research involves the application of meta-analysis to study the correlation between the complexity factors identified in the first stage, aiming for heterogeneity, identification of patterns and directing to achieve robust conclusions by using sensitivity analysis. The thesis proposes a new model of complexity factors for oil & gas engineering projects in the MENA region. The model is designed to facilitate the analysis of the project complexity landscape and to define requirements for oil & gas organisations involved with the delivery of projects and programmes to cope with different complexity factors within and across the MENA region. The outcomes include substantial relationship between technical and health, safety & environment complexity factors and project performance despite the mediation of project management complexity factors, yet the organizational complexity factors can be observed at a significant level when project management in complexity factors are considered as a mediator in the model (Ziadat, 2016).

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Bondorowicz, Stefan. "Adaptive control of complex dynamic systems." Thesis, University of Oxford, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.302787.

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Martinet, Lucie. "Réseaux dynamiques de terrain : caractérisation et propriétés de diffusion en milieu hospitalier." Thesis, Lyon, École normale supérieure, 2015. http://www.theses.fr/2015ENSL1010/document.

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Durant cette thèse, nous nous sommes intéressés aux outils permettant d'extraire les propriétés structurelles et temporelles de réseaux dynamiques ainsi que les caractéristiques de certains scénarios de diffusion pouvant s'opérer sur ces réseaux. Nous avons travaillé sur un jeu de données spécifiques, issu du projet MOSAR, qui comporte entre autre le réseau de proximité des personnes au cours du temps durant 6 mois à l'hôpital de Berk-sur-mer. Ce réseau est particulier dans le sens où il est constitué de trois dimensions: temporelle, structurelle par la répartition des personnes en services et fonctionnelle car chaque personne appartient à une catégorie socio-professionnelle. Pour chacune des dimensions, nous avons utilisé des outils existants en physique statistique ainsi qu'en théorie des graphes pour extraire des informations permettant de décrire certaines propriétés du réseau. Cela nous a permis de souligner le caractère très structuré de la répartition des contacts qui suit la répartition en services et mis en évidence les accointances entre certaines catégories professionnelles. Concernant la partie temporelle, nous avons mis en avant l'évolution périodique circadienne et hebdomadaire ainsi que les différences fondamentales entre l'évolution des interactions des patients et celle des personnels. Nous avons aussi présenté des outils permettant de comparer l'activité entre deux périodes données et de quantifier la similarité de ces périodes. Nous avons ensuite utilisé la technique de simulation pour extraire des propriétés de diffusion de ce réseau afin de donner quelques indices pour établir une politique de prévention
In this thesis, we focus on tools whose aim is to extract structural and temporal properties of dynamic networks as well as diffusion characteristics which can occur on these networks. We work on specific data, from the European MOSAR project, including the network of individuals proximity from time to time during 6 months at the Brek-sur-Mer Hospital. The studied network is notable because of its three dimensions constitution : the structural one induced by the distribution of individuals into distinct services, the functional dimension due to the partition of individual into groups of socio-professional categories and the temporal dimension.For each dimension, we used tools well known from the areas of statistical physics as well as graphs theory in order to extract information which enable to describe the network properties. These methods underline the specific structure of the contacts distribution which follows the individuals distribution into services. We also highlight strong links within specific socio-professional categories. Regarding the temporal part, we extract circadian and weekly patterns and quantify the similarities of these activities. We also notice distinct behaviour within patients and staff evolution. In addition, we present tools to compare the network activity within two given periods. To finish, we use simulations techniques to extract diffusion properties of the network to find some clues in order to establish a prevention policy

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Faller, Daniel. "Analysis and dynamic modelling of complex systems." [S.l. : s.n.], 2003. http://www.freidok.uni-freiburg.de/volltexte/777.

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Garcia, Cantu Ros Anselmo. "Thermodynamic and kinetic aspects of interaction networks." Doctoral thesis, Universite Libre de Bruxelles, 2007. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/210420.

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In view of the fact that a same complex phenomenon can be approached by different conceptual frameworks, it is natural to inquire on the possibility to find connections between different types of quantities, such as topological, dynamical, statistical or thermodynamical, characterizing the same system. The present work is built on the idea that this line of approach can provide interesting insights on possible universal principles governing complex phenomena. In Chapter I we introduce concepts and tools of dynamical systems and thermodynamics as applied in macroscopic scale description as well as, for a later use, a number of selected representative models. In Chapter II we briefly present the elements of the theory of Markov processes describing a large class of stochastic process and also introduce some important concepts on the probabilistic description of deterministic systems. This chapter ends with a thermodynamic formulation accounting for the evolution of the entropy under the effect of stochastic fluctuations. In Chapter III, after introducing the main concepts and recent advances in network theory, we provide a connection between dynamical systems and network theory, which shows how universal structural properties of evolving networks can arise from deterministic dynamics. More specifically, we show explicitly the relation between the connectivity patterns of these networks and the indicators of the underlying dynamics, such as the local Lyapunov exponents. Our analysis is applied to representative models of chaotic maps, chaotic flows and is finally extended to stochastic processes. In Chapter IV we address the inverse problem, namely, processes whose dynamics is determined, in part, by the structure of the network in which they are embedded. In particular, we focus on systems of particles diffusing on a lattice and reacting instantaneously upon encountering each other. We study the role of the topology, the degree of synchronicity of motion and the reaction mechanism on the efficiency of the process. This lead us to identify a common generic mechanism responsible for the behavior of the efficiency, as a function of the control parameters. Finally, in Chapter V we study the connection between the topology and the thermodynamic properties of reaction networks, with focus on the entropy production and the system’s efficiency at nonequilibrium steady states. We also explore the connection between dynamic and thermodynamic properties of nonlinear feedbacks, as well as the response properties of reaction networks against both deterministic and stochastic external perturbations. We address networks of varying topologies, from regular lattices to complex structures./Le présent travail s’inscrit dans le domaine de recherche sur les systèmes complexes. Différentes approches, basées des systèmes dynamiques, de la thermodynamique des systèmes hors d’équilibre, de la physique statistique et, plus récemment, de la théorie des réseaux, sont combinés afin d’explorer des liens entre différentes types de grandeurs qui caractérisent certaines classes de comportements complexes. Dans le Chapitre I nous introduisons les principaux concepts et outils de systèmes dynamiques et de thermodynamique. Dans le Chapitre II nous présentons premièrement des éléments de la théorie de processus de Markov, ainsi que les concepts à la base de la description probabiliste des systèmes déterministes. Nous finissons le chapitre en proposant une formulation thermodynamique qui décrit l’évolution de l’entropie hors d’équilibre, soumis à l’influence de fluctuations stochastiques. Dans le Chapitre III nous introduisons les concepts de base en théorie des réseaux, ainsi qu’un résumé générale des progrès récents dans le domaine. Nous établissons ensuite une connexion entre la théorie des systèmes dynamiques et la théorie de réseaux. Celle-ci permet d’approfondir la compréhension des mécanismes responsables de l’émergence des propriétés structurelles dans des réseaux crées par des lois dynamiques déterministes. En particulier, nous mettons en évidence la relation entre des motifs de connectivité de ce type de réseaux et des indicateurs de la dynamique sous-jacente, tel que des exposant de Lyapounov locaux. Notre analyse est illustrée par des applications et des flots chaotiques et étendue à des processus stochastiques. Dans le Chapitre IV nous étudions le problème complémentaire, à savoir, celui de processus dont la dynamique est déterminée, en partie, par la structure du réseau dans lequel elle se déroule. Plus précisément, nous nous concentrons sur le cas de systèmes de particules réactives, diffusent au travers d’un réseau et réagissant instantanément lorsqu’un rencontre se produit entre elles. Nous étudions le rôle de la topologie, du degré de synchronicité des mouvements et aussi celui du mécanisme de réaction sur l’efficacité du processus. Dans les différents modèles étudiés, nous identifions un mécanisme générique commun, responsable du comportement de l’efficacité comme fonction des paramètres de contrôle. Enfin, dans le Chapitre V nous abordons la connexion entre la topologie et les propriétés thermodynamiques des réseaux de réactions, en analysant le comportement local et global de la production d’entropie et l’efficacité du système dans des état stationnaires de non-équilibre. Nous explorons aussi la connexion entre la dynamique et les propriétés de boucles de rétroaction non linéaires, ainsi que les propriétés de réponse des réseaux de réaction à des perturbations stochastiques et déterministes externes. Nous considérons le cas de réseaux à caractère régulier aussi bien que celui de réseaux complexes.

Doctorat en Sciences
info:eu-repo/semantics/nonPublished

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Mihata, Kevin K. "How to build a complex theory : complex systems, computer simulation, and sociological theory /." Thesis, Connect to this title online; UW restricted, 2000. http://hdl.handle.net/1773/8928.

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Ding, Limei. "On modeling and control of complex dynamic systems." Licentiate thesis, Luleå, 2000. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-26097.

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Nonlinear complex multi-input multi-output process is very troublesome to control. It is usually also ill-modeled. The problem of such process both in control and modeling requires a comprehensive utilization of various techniques. The thesis presents the methods for the modeling and control of complex systems. A typical example of complex processes is mineral flotation that characterized by multivariable, nonlinearities, strong interactions, stochastic disturbances, and large and variable delay times. The dynamic nonlinear model of a inverse continuous flotation process is developed based on the first order kinetics. The complexity of mineral flotation in modeling and control is shown by the analysis of the dynamic model and the relation between the process inputs and the process parameters. As an attractive alternative of conventional control technologies, fuzzy logic control is discussed for the control of an MIMO nonlinear flotation system and the simulation of the control system is carried out. LQG optimal control of the pulp level, a subsystem in a flotation process is studied and the robustness is analyzed based on the structured singular value. The control of infinite dimensional systems is known to all a knotty problem. Orthogonal collocation method, which is one of the methods of weighted residual, is employed to reduce the infinite dimensional model of the systems. In a case study a time delay system is approximated using the orthogonal collocation and a robust controller of the delay system is synthesized based on the method introduced by Glover and McFarlane in 1989. The robustness degradation caused by model reduction is discussed. The results show that the strategies studied in the thesis are available to solve the relevant modeling and control problems of complex systems.

Godkänd; 2000; 20070318 (ysko)

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Gupta, Amit. "Model reduction and simulation of complex dynamic systems /." Online version of thesis, 1990. http://hdl.handle.net/1850/11265.

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Turalska, Malgorzata A. "Temporal Properties Of Dynamic Processes On Complex Networks." Thesis, University of North Texas, 2011. https://digital.library.unt.edu/ark:/67531/metadc103403/.

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Many social, biological and technological systems can be viewed as complex networks with a large number of interacting components. However despite recent advancements in network theory, a satisfactory description of dynamic processes arising in such cooperative systems is a subject of ongoing research. In this dissertation the emergence of dynamical complexity in networks of interacting stochastic oscillators is investigated. In particular I demonstrate that networks of two and three state stochastic oscillators present a second-order phase transition with respect to the strength of coupling between individual units. I show that at the critical point fluctuations of the global order parameter are characterized by an inverse-power law distribution and I assess their renewal properties. Additionally, I study the effect that different types of perturbation have on dynamical properties of the model. I discuss the relevance of those observations for the transmission of information between complex systems.

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Frenken, Koen. "Understanding product innovation using complex systems theory." [S.l. : Amsterdam : s.n.] ; Universiteit van Amsterdam [Host], 2001. http://dare.uva.nl/document/61019.

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Yang, Ang Information Technology &amp Electrical Engineering Australian Defence Force Academy UNSW. "A networked multi-agent combat model : emergence explained." Awarded by:University of New South Wales - Australian Defence Force Academy. School of Information Technology and Electrical Engineering, 2007. http://handle.unsw.edu.au/1959.4/38823.

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Simulation has been used to model combat for a long time. Recently, it has been accepted that combat is a complex adaptive system (CAS). Multi-agent systems (MAS) are also considered as a powerful modelling and development environment to simulate combat. Agent-based distillations (ABD) - proposed by the US Marine Corp - are a type of MAS used mainly by the military for exploring large scenario spaces. ABDs that facilitated the analysis and understanding of combat include: ISAAC, EINSTein, MANA, CROCADILE and BactoWars. With new concepts such as networked forces, previous ABDs can implicitly simulate a networked force. However, the architectures of these systems limit the potential advantages gained from the use of networks. In this thesis, a novel network centric multi-agent architecture (NCMAA) is pro-posed, based purely on network theory and CAS. In NCMAA, each relationship and interaction is modelled as a network, with the entities or agents as the nodes. NCMAA offers the following advantages: 1. An explicit model of interactions/relationships: it facilitates the analysis of the role of interactions/relationships in simulations; 2. A mechanism to capture the interaction or influence between networks; 3. A formal real-time reasoning framework at the network level in ABDs: it interprets the emergent behaviours online. For a long time, it has been believed that it is hard in CAS to reason about emerging phenomena. In this thesis, I show that despite being almost impossible to reason about the behaviour of the system by looking at the components alone because of high nonlinearity, it is possible to reason about emerging phenomena by looking at the network level. This is undertaken through analysing network dynamics, where I provide an English-like reasoning log to explain the simulation. Two implementations of a new land-combat system called the Warfare Intelligent System for Dynamic Optimization of Missions (WISDOM) are presented. WISDOM-I is built based on the same principles as those in existing ABDs while WISDOM-II is built based on NCMAA. The unique features of WISDOM-II include: 1. A real-time network analysis toolbox: it captures patterns while interaction is evolving during the simulation; 2. Flexible C3 (command, control and communication) models; I 3. Integration of tactics with strategies: the tactical decisions are guided by the strategic planning; 4. A model of recovery: it allows users to study the role of recovery capability and resources; 5. Real-time visualization of all possible information: it allows users to intervene during the simulation to steer it differently in human-in-the-loop simulations. A comparison between the fitness landscapes of WISDOM-I and II reveals similarities and differences, which emphasise the importance and role of the networked architecture and the addition of strategic planning. Lastly but not least, WISDOM-II is used in an experiment with two setups, with and without strategic planning in different urban terrains. When the strategic planning was removed, conclusions were similar to traditional ABDs but were very different when the system ran with strategic planning. As such, I show that results obtained from traditional ABDs - where rational group planning is not considered - can be misleading. Finally, the thesis tests and demonstrates the role of communication in urban ter-rains. As future warfighting concepts tend to focus on asymmetric warfare in urban environments, it was vital to test the role of networked forces in these environments. I demonstrate that there is a phase transition in a number of situations where highly dense urban terrains may lead to similar outcomes as open terrains, while medium to light dense urban terrains have different dynamics

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Sanguinetti, Guido. "Complex geometry of dual isomonodromic systems." Thesis, University of Oxford, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.275207.

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Ding, Limei. "Modeling control and analysis of complex dynamic chemical systems /." Luleå, 2003. http://epubl.luth.se/1402-1544/2003/28.

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Sprittles, James Edward. "Dynamic wetting/dewetting processes in complex liquid-solid systems." Thesis, University of Birmingham, 2010. http://etheses.bham.ac.uk//id/eprint/1095/.

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In this thesis, the phenomenon of a microdrop impacting onto and spreading over surfaces of constant and variable wettability is investigated. The study is motivated by wide-ranging industrial applications of ink-jet printing technologies, in particular used by our industrial sponsor Kodak Ltd. Mathematical models for dynamic wetting phenomena are incorporated into a specially developed finite element based numerical platform. By examining different models, it was found for the first time that the interface formation model is capable of describing the experimentally observed non-uniqueness of the relationship between the contact-line speed and the dynamic contact angle. It is shown that, the interface formation model naturally captures the effect which variations in the wettability of the solid surface have on an adjacent flow, so that the model can be used, without any ad-hoc alterations, to consider the spreading of microdrops on such solids. An investigation of the effect that variation of the model's parameters has on the characteristics of the impact and spreading of microdrops has been carried out.

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Ludlow, Richard Frederick. "Molecular networks : from dynamic combinatorial libraries to complex systems." Thesis, University of Cambridge, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.611116.

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Tong, Xiao Thomas. "Statistical Learning of Some Complex Systems: From Dynamic Systems to Market Microstructure." Thesis, Harvard University, 2013. http://dissertations.umi.com/gsas.harvard:10917.

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A complex system is one with many parts, whose behaviors are strongly dependent on each other. There are two interesting questions about complex systems. One is to understand how to recover the true structure of a complex system from noisy data. The other is to understand how the system interacts with its environment. In this thesis, we address these two questions by studying two distinct complex systems: dynamic systems and market microstructure. To address the first question, we focus on some nonlinear dynamic systems. We develop a novel Bayesian statistical method, Gaussian Emulator, to estimate the parameters of dynamic systems from noisy data, when the data are either fully or partially observed. Our method shows that estimation accuracy is substantially improved and computation is faster, compared to the numerical solvers. To address the second question, we focus on the market microstructure of hidden liquidity. We propose some statistical models to explain the hidden liquidity under different market conditions. Our statistical results suggest that hidden liquidity can be reliably predicted given the visible state of the market.
Statistics

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Bremner, Jonathan James. "Complex torque coefficient analysis of multi-device power systems." Thesis, University of Glasgow, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.362955.

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Lee, Chae Young. "Analysis and optimization of complex nonserial dynamic programming network systems." Diss., Georgia Institute of Technology, 1985. http://hdl.handle.net/1853/24355.

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Vasandani, Vijay. "Intelligent tutoring for diagnostic problem solving in complex dynamic systems." Diss., Georgia Institute of Technology, 1991. http://hdl.handle.net/1853/24934.

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Ganapathy, Subhashini. "HUMAN-CENTERED TIME-PRESSURED DECISION MAKING IN DYNAMIC COMPLEX SYSTEMS." Wright State University / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=wright1152229142.

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Schön, Thomas B. "Estimation of Nonlinear Dynamic Systems : Theory and Applications." Doctoral thesis, Linköpings universitet, Reglerteknik, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-7124.

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This thesis deals with estimation of states and parameters in nonlinear and non-Gaussian dynamic systems. Sequential Monte Carlo methods are mainly used to this end. These methods rely on models of the underlying system, motivating some developments of the model concept. One of the main reasons for the interest in nonlinear estimation is that problems of this kind arise naturally in many important applications. Several applications of nonlinear estimation are studied. The models most commonly used for estimation are based on stochastic difference equations, referred to as state-space models. This thesis is mainly concerned with models of this kind. However, there will be a brief digression from this, in the treatment of the mathematically more intricate differential-algebraic equations. Here, the purpose is to write these equations in a form suitable for statistical signal processing. The nonlinear state estimation problem is addressed using sequential Monte Carlo methods, commonly referred to as particle methods. When there is a linear sub-structure inherent in the underlying model, this can be exploited by the powerful combination of the particle filter and the Kalman filter, presented by the marginalized particle filter. This algorithm is also known as the Rao-Blackwellized particle filter and it is thoroughly derived and explained in conjunction with a rather general class of mixed linear/nonlinear state-space models. Models of this type are often used in studying positioning and target tracking applications. This is illustrated using several examples from the automotive and the aircraft industry. Furthermore, the computational complexity of the marginalized particle filter is analyzed. The parameter estimation problem is addressed for a relatively general class of mixed linear/nonlinear state-space models. The expectation maximization algorithm is used to calculate parameter estimates from batch data. In devising this algorithm, the need to solve a nonlinear smoothing problem arises, which is handled using a particle smoother. The use of the marginalized particle filter for recursive parameterestimation is also investigated. The applications considered are the camera positioning problem arising from augmented reality and sensor fusion problems originating from automotive active safety systems. The use of vision measurements in the estimation problem is central to both applications. In augmented reality, the estimates of the camera’s position and orientation are imperative in the process of overlaying computer generated objects onto the live video stream. The objective in the sensor fusion problems arising in automotive safety systems is to provide information about the host vehicle and its surroundings, such as the position of other vehicles and the road geometry. Information of this kind is crucial for many systems, such as adaptive cruise control, collision avoidance and lane guidance.

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Schön, Thomas B. "Estimation of Nonlinear dynamic systems : theory and applications /." Linköping : Univ, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-7124.

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ROA, GONZÁLEZ Iván René. "The h-theory: universality classes of hierarchical complex systems." Universidade Federal de Pernambuco, 2017. https://repositorio.ufpe.br/handle/123456789/25596.

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ROA GONZÁLEZ, Iván René, também é conhecido em citações bibliográficas por: GONZÁLEZ, Iván René Roa
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CNPq
Complex dynamical systems can be characterized through the time series associated with dynamical variables, which yield important information on the underlying stochastic process. The probability density function, the temporal correlation function, the power spectrum, and the memory function are examples of statistical properties that can be extracted from the time series. In this thesis, we are particularly interested in describing complex phenomena in which the stationary distribution of the time series of the main dynamical variable (the signal) exhibits large deviations from Gaussian statistics, possibly showing long and heavy tails. This kind of phenomena is present in many areas of physics, biology, and economics. However, our interest is focused on spectral fluctuations in non-integrable ballistic cavities, intensity fluctuations in random lasers, turbulence in fluids, stock prices fluctuations in financial markets. We shall attempt to describe these phenomena as a composition of distributions with distinct space/time scales which arise from a hierarchical dynamics with a coupling between contiguous scales. The model to be used, denominated H-Theory, was recently proposed by our research group and consists of a set of coupled stochastic differential equations, whose stationary solution leads to a parametric family of distributions represented by Fox H-function. This result unifies and generalizes the universality classes of superstatistics, which is a formalism that has been successfully used to describe systems with two separated time scales.
na caracterização de sistemas complexos nos quais a distribuição estacionária da série temporal da variável dinâmica principal (o sinal) desvia-se substancialmente da gaussiana, podendo exibir caudas longas e pesadas. Exemplos de sistemas deste tipo podem ser encontrados em diversas áreas da física, da biologia e da economia. Contudo, centraremos nosso foco nos fenômenos de flutuações espectrais em turbulência em fluidos, variações nos preços de ações no mercado financeiro, flutuações de intensidade em lasers aleatórios em fibra óptica e estatística espectral de cavidades balísticas não-integráveis. Caracterizamos esses fenômenos como resultado da composição de distribuições com distintas escalas espaçiais/temporais que resultam de uma dinâmica hierárquica com acoplamento entre escalas contíguas. O modelo a ser usado, denominado teoria H, foi recentemente proposto por nosso grupo de pesquisa e consiste de um sistema de equações diferenciais estocásticas acopladas, cuja solução estacionária produz uma família paramétrica de distribuições representadas por funções H de Fox. Este resultado unifica e estende para múltiplas escalas as classes de universalidade da superestatística, que é um formalismo que tem sido usado com sucesso para descrever sistemas dinâmicos complexos com duas escalas temporais separadas.

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Dissertations / Theses on the topic 'Complex Dynamic Systems Theory'

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