Complex nonlinear and chaotic responses have been recently observed in various compliant ocean systems. These systems are characterized by a nonlinear mooring restoring force and a coupled fluid-structure interaction exciting force. A general class of ocean mooring system models is formulated by incorporating a variable mooring configuration and the exact form of the hydrodynamic excitation. The multi-degree of freedom system, subjected to combined parametric and external excitation, is shown to be complex, coupled and strongly nonlinear. Stability analysis by a Liapunov function approach reveals global system attraction which ensures that solutions remain bounded for small excitation. Construction of the system's Poincare map and stability analysis of the map's fixed points correspond to system stability of near resonance periodic orbits. Investigation of nonresonant solutions is done by a local variational approach. Tangent and period doubling bifurcations are identified by both local stability analysis techniques and are further investigated to reveal global bifurcations. Application of Melnikov's method to the perturbed averaged system provides an approximate criterion for the existence of transverse homoclinic orbits resulting in chaotic system dynamics. Further stability analysis of the subharmonic and ultraharmonic solutions reveals a cascade of period doubling which is shown to evolve to a strange attractor. Investigation of the bifurcation criteria obtained reveals a steady state superstructure in the bifurcation set. This superstructure identifies a similar bifurcation pattern of coexisting solutions in the sub, ultra and ultrasubharmonic domains. Within this structure strange attractors appear when a period doubling sequence is infinite and when abrupt changes in the size of an attractor occur near tangent bifurcations. Parametric analysis of system instabilities reveals the influence of the convective inertial force which can not be neglected for large response and the bias induced by the quadratic viscous drag is found to be a controlling mechanism even for moderate sea states. Thus, stability analyses of a nonlinear ocean mooring system by semi-analytical methods reveal the existence of bifurcations identifying complex periodic and aperiodic nonlinear phenomena. The results obtained apply to a variety of nonlinear ocean mooring and towing system configurations. Extensions and applications of this research are discussed. / Graduation date: 1992

In many systems, instabilities can lead to time-dependent behavior, and instabilities can act as mechanisms for sustained chaos; an understanding of the dynamical modes governing instability is thus essential for prediction and/or control in such systems. In this thesis work, we have developed an approach toward characterizing instabilities quantitatively, from experiments on the prototypical Rayleigh-Bénard convection system. We developed an experimental technique for preparing a given convection pattern using rapid optical actuation of pressurized SF6, a greenhouse gas. Real-time analysis of convection patterns was developed as part of the implementation of closed-loop control of straight roll patterns. Feedback control of the patterns via actuation was used to guide patterns to various system instabilities. Controlled, spatially localized perturbations were applied to the prepared states, which were observed to excite the dominant system modes. We extracted the spatial structure and growth rates of these modes from analysis of the pattern evolutions. The lifetimes of excitations were also measured, near a particular instability; a critical wavenumber was found from the observed dynamical slowing near the bifurcation. We will also describe preliminary results of using a state estimation algorithm (LETKF) on experimentally prepared non-periodic patterns in a cylindrical convection cell.

Thesis (doctoral)--Rijksuniversiteit te Utrecht, 1983. / "Stellingen": [6] p. inserted. Includes bibliographical references (p. 253-257) and index.

Thesis (Ph. D.)--Ohio State University, 2007. / Title from first page of PDF file. Includes bibliographical references (p. 204-214).

M. Tech. Electrical Engineering. / Proposes a public-key encryption scheme based on Qi hyperchaos, which is considered much better than chaos and other hyperchaos in terms of pseudo-randomness. In an environment where digital information is being extensively used, a cat map based hyperchaotic system is proposed. This map is used to design the public key encryption scheme that uses private keys, public keys and shared private keys. This encryption is tested successfully on text messages and images. The application of the hyperchaos-based scheme on a web server client platform concludes this work. MATLAB is used for simulation. PHP, HTML, and C are used in the development of the web form and the chat application.

Orientador: Marco Antonio Teixeira / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Matemática, Estatística e Computação Científica / Made available in DSpace on 2018-08-20T09:21:57Z (GMT). No. of bitstreams: 1 Damacena_ThaisBorges_M.pdf: 1821590 bytes, checksum: 6b7242d4adbe1ac4b9b0dcbe04dd70b7 (MD5) Previous issue date: 2012 / Resumo: Um campo vetorial descontínuo 3D sobre uma superfície suave de codimensão um, pode ser genericamente tangente a ambos os lados da superfície em um ponto p. Os pontos onde esse fenômeno ocorre são chamados de singularidade dobra-dobra. Nesse trabalho, estudamos a dinâmica local de um sistema dinâmico suave por partes tri-dimensional em uma dobra-dobra. Vimos que a dinâmica local depende principalmente de um único parâmetro que controla uma bifurcação. Especificamente no caso onde as dobras são ambas invisíveis, a chamada singularidade Teixeira, encontramos que o sistema pode admitir um fluxo exibindo dinâmica caótica, mas não determinística / Abstract: A 3D discontinuous vector field on a smooth surface of codimension one, can be generically tangent to both sides of the surface at a point p. The points where this phenomenon occurs are called two-fold singularities. In this project, we study the local dynamics of a three-dimensional piecewise smooth dynamical systems at a two-fold. We have seen that the local dynamics depends mainly on a single parameter that controls a bifurcation. Specifically in the case where the folds are both invisibles, the so-called singularity Teixeira, we find that the system can admit a flow exhibiting chaotic but non-deterministic dynamics / Mestrado / Matematica / Mestre em Matemática

This study investigated relationships between marketing success, the level of external environmental complexity and turbulence, and marketing mix tactics. The literature suggested that more successful companies in simple and stable environments use stabilising marketing tactics, while more successful companies in complex and turbulent environments use destabilising tactics, regardless of industry habits, management preferences or market sector. A marketing mix model for the different environments was developed using a chaos and complexity theory perspective. The study was exploratory, using a qualitative, case study technique. Data was collected via depth interviews and document analysis from four companies in the information technology (IT) and packaging industries. These industries were identified as, respectively, the most complex and turbulent, and the simplest and most stable, South African environments. Two companies from each industry were chosen to reflect more successful and less successful companies. The more successful company in the complex/turbulent environment was found to use destabilising tactics, as did the more successful company in the simple/stable environment. Therefore, contrary to expectations, it appears that destabilising tactics contribute more to success than stabilising tactics do, regardless of the environment. It was also found, contrary to expectations, that stabilising tactics were used by both the less successful companies. The research concluded that destabilising tactics are related to more success and stabilising tactics to less success. The lack of clear differentiation between the two industries may be because the whole South African environment is complex and turbulent, because the packaging industry is not sufficiently simple and stable to differentiate it from the IT industry or because packaging industry managers perceive their industry to be complex and turbulent and act accordingly. Despite these uncertainties, the research showed the marketing mix model to be reasonably accurate for the complex/turbulent environment, and therefore of potential value to South African companies. To overcome the equivocal findings, further research is recommended in different industries, in countries with different levels of complexity and turbulence and into specific marketing mix tactics. Research into managers’ perceptions of environmental complexity and turbulence and into co-evolution of marketing tactics and external environments would also be of value.

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Orientador: Kyoko Furuya / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Fisica Gleb Wataghin / Made available in DSpace on 2018-08-04T01:53:26Z (GMT). No. of bitstreams: 1 SousaJunior_DelcidesFlaviode_M.pdf: 32680218 bytes, checksum: aa259799e554166260b37c235e19a803 (MD5) Previous issue date: 1998 / Resumo:Apresentamos nesta dissertação um estudo da conexão entre a Mecânica Clássica e a Mecânica Quântica através dos diagramas de energia vs. período para as principais famílias de órbitas periódicas de um dado sistema dinâmico. O diagrama quântico é definido através do espectro do sistema quântico correspondente, que mostra cicatrizes dessas famílias no regime semiclássico. Dois sistemas hamiltonianos, com dois graus de liberdade e apresentando comportamento misto ( caótico e regular ) , são estudados. O primeiro é o pêndulo elástico, usado como paradigma de caos clássico. Aspectos essenciais da sua dinâmica são estudados e o diagrama clássico de energia vs. período com as principais famílias de órbitas periódicas é construido. O segundo sistema é o Hamiltoniano Spin-Bóson, um sistema quântico para o qual trabalhos anteriores definiram um análogo clássico, para o qual estudou-se o comportamento caótico e famílias de órbitas periódicas. Uma versão quântica deste diagrama de energia vs. período é mostrada para este modelo. As duas versões são comparadas no regime de caos misto e o ajuste no limite semiclássico discutido. Uma concordância qualitativa é obtida, com indicações de que as cicatrizes são mais acentuadas nas regiões onde ocorrem bifurcações de órbitas periódicas / Abstract:We study the connection between Classical and Quantum Mechanics using the plots of Energy VS. Period for the main families of periodic orbits of certain dynamical system .The quantum E-t plot is defined through the spectrum of the corresponding quantum system, which shows scars of the classical families in the semiclagsical regime. Two Hamiltonian systems with two degrees of freedom both displaying mixed (chaotic and regular) behaviour are analized. The first one is the elastic pendulum, its behaviour ususally presented as a paradigm of classical chaos. Essential aspects of its dinamics are studied to some extent and the classical (E, t ) plot is shown. The second system is the Spin- Boson Hamiltonian, a quantum system for which previous works have defined a classical analogue with chaotic behaviour and compiled the main families of periodic orbits. A quantum version of the (E, t ) plot for this model is shown, and the classical and quantum plots are compared in the regime of soft chaos. The fitting in the semiclassical limit is discussed with a qualitative agreement that indicates enhancements of the scars in the regions where bifurcations of period orbits occur / Mestrado / Física / Mestre em Física

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