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Nonlinear oscillations, bifurcations and chaos in ocean mooring systemsGottlieb, Oded 03 December 1991 (has links)
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
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The study of chaotic phase synchronization of nonlinear electronic circuits and solid-state laser systemsLin, Chien-Hui 12 July 2012 (has links)
We study the chaotic phase synchronization (CPS) between the external periodically driving signals and the nonlinear dynamic systems. The periodical signal was applied to drive the Chua circuit system with two-scroll attractor and the four-scroll attractor circuit system. The phase synchronization between the outputs of these two circuit systems and the driving signals were investigated. Besides, the chaotic phase synchronization of the periodically pump-modulated microchip Nd:YVO4 laser and the microchip Nd:YVO4 laser with optical feedback were also examined in this study.
Phase synchronization (PS) transition of these periodically driven nonlinear dynamic systems exhibited via the stroboscopic technique and recurrence probability. The recurrence probability and correlation probability of recurrence were utilized to estimate the degree of PS. In this thesis, the degree of PS was studied by taking into account the amplitude and frequency of the external driving signal. The experimental compatible numerical simulations also reflected the fact that the Arnold tongues are experimentally and numerically exhibited in the periodically driven nonlinear dynamic systems.
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Chaotic Demodulation Under InterferenceErdem, Ozden 01 September 2006 (has links) (PDF)
Chaotically modulated signals are used in various engineering areas such as communication systems, signal processing applications, automatic control systems. Because chaotically modulated signal sequences are broadband and noise-like signals, they are used to carry binary signals especially in secure communication systems.
In this thesis, a target tracking problem under interference at chaotic communication systems is investigated. Simulating the chaotic communication system, noise-like signal sequences are generated to carry binary signals. These signal sequences are affected by Gaussian channel noise and interference while passing through the communication channel. At the receiver side, target tracking is performed using Optimum Decoding Based Smoothing Algorithm. The estimation performances of optimum decoding based smoothing algorithm at one dimensional chaotic systems and nonlinear chaotic algorithm map are presented and compared with the performance of the Extended Kalman Filter application.
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Mechanisms of instability in Rayleigh-Bénard convectionPerkins, Adam Christopher 25 August 2011 (has links)
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.
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Nekilnojamojo turto plėtros tendencijų ir problemų analizė / The Analysis of Tends and Problems of Real Estate DevelopmentBakšytė, Vaida 01 February 2012 (has links)
Baigiamajame magistro darbe nagrinėjama darnios nekilnojamojo turto plėtros problemos ir tendencijos, pateikiamos pasaulinės urbanizacijos keliamos grėsmės ir chaotiškos plėtros problematika, aprašomos Lietuvos gyvenamųjų pastatų plėtros perspektyvos ir atliekama pasirinktų Lietuvoje vykdomų nekilnojamojo turto plėtros projektų analizė. / The tends and problems of sustainable real estate development are analysed, the global threat posed by urbanization and chaotic development issues are given, Lithuanian residential development perspectives are described and analyzed in the final master's work.
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Chaotic Digital Modulation And DemodulationOzturk, Uygar 01 December 2005 (has links) (PDF)
This thesis considers a communication system with chaotic modulation. Noise-like signals are generated by chaotic systems with different parameters to modulate binary digital signals. Demodulation is performed by both the Extended Kalman Filter (EKF) and Optimum Decoding Based Smoothing Algorithm (ODSA). Simulations are performed using both of these algorithms for different parameters affecting the performance of the communication system. Simulation results of these algorithms are compared.
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Thermal and hydrodynamic interactions between a liquid droplet and a fluid interfaceGreco, Edwin F. 15 January 2008 (has links)
The research presented in this thesis was motivated by the desire to understand the flow field within a new digital microfluidic device currently under development. This required an investigation of the dynamics of a droplet migrating along the surface of another fluid due to interfacial surface tension gradients. The quantitative analysis of the flow field presented in this thesis provides the first known solution for the velocity field in a migrating droplet confined to an interface.
The first step towards gaining insight into the flow field was accomplished by using the method of reflections to obtain an analytical model for a submerged droplet migrating near a free surface. The submerged droplet model enabled the analysis of the velocity field and droplet migration speed and their dependence on the fluid properties. In general, the migration velocity of a submerged droplet was found to differ dramatically from the classic problem of thermocapillary migration in an unbounded substrate.
A boundary-collocation scheme was developed to determine the flow field and migration velocity of a droplet floating trapped at the air-substrate interface. The numerical method was found to produce accurate solutions for the velocity and temperature fields for nearly all parameters. This numerical scheme was used to judge the accuracy of the flow field obtained by the submerged droplet model. In particular, the model was tested using parameter values taken from a digital microfluidic device. It was determined that the submerged droplet model captured most of the flow structure within the microfluidic droplet. However, for a slightly different choice of parameters, agreement between the two methods was lost. In this case, the numerical scheme was used to uncover novel flow structures.
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Chaos, yet no chance to get lost order and structure in the chaotic dynamical behaviour of one-dimensional noninvertible axiom a mappings, arising in discrete biological models /Nusse, Helena Engelina, January 1900 (has links)
Thesis (doctoral)--Rijksuniversiteit te Utrecht, 1983. / "Stellingen": [6] p. inserted. Includes bibliographical references (p. 253-257) and index.
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Models of EEG data mining and classification in temporal lobe epilepsy: wavelet-chaos-neural network methodology and spiking neural networks /Ghosh Dastidar, Samanwoy, January 2007 (has links)
Thesis (Ph. D.)--Ohio State University, 2007. / Title from first page of PDF file. Includes bibliographical references (p. 204-214).
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Δημιουργία προγραμματιστικού περιβάλλοντος για επεξεργασία βιομαγνητικών σημάτων (bio signal processing software)Σκαρλάς, Λάμπρος Β. 01 September 2010 (has links)
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