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Uncertainties in both loading and structural characteristics can adversely affect the response and reliability of a structure. Parameter uncertainties in structural dynamics can arise due to several sources. These include variations due to intrinsic material property variability, measurement errors, manufacturing and assembly errors, differences in modeling and solution procedures. Problems of structural dynamics with randomly distributed spatial inhomogeneities in elastic, mass, and damping properties, have been receiving wide attention. Several mathematical and computational issues include discretization of random fields, characterization of random eigensolutions, inversion of random matrices, solutions of stochastic boundary-value problems, and description of random matrix products. Difficulties are encountered when one has to include interaction between nonlinear and stochastic system characteristics, or if one is interested in controlling the system response. The study of structural systems including the effects of system nonlinearity in the presence of parameter uncertainties presents serious challenges and difficulties to designers and reliability engineers. In the analysis of large structures, the situation for substructuring frequently arises due to the repetition of identical assemblages (substructures), within a structure, and the general need to reduce the size of the problem, particularly in the case of non-linear inelastic dynamic analysis. A small reduction in the model size can have a large effect on the storage and time requirement. A primary structural dynamic system may be coupled to subsystems such as piping systems in a nuclear reactor or in a chemical plant. Usually subsystem in itself is quite complex and its modeling with finite elements may result in a large number of degrees of freedom. The reduced subsystem model should be of low-order yet capturing the essential dynamics of the subsystem for useful integration with the primary structure. There are two major issues to be studied: one, techniques for analyzing a complex structure into component subsystems, analyzing the individual sub-system dynamics, and from thereon determining the dynamics of the structure after assembling the subsystems. The nonlinearity due to support gap effects such as supports for piping system in nuclear reactors further complicates the problem. The second is the issue of reviewing the methods for reducing the model-order of the component subsystems such that the order of the global dynamics, after assembly, is within some predefined limits. In the reliability analysis of complex engineering structures, a very large number of the system parameters have to be considered as random variables. The parameter uncertainties are modeled as random variables and are assumed to be time independent. Here the problem would be to reduce the number of random variables without sacrificing the accuracy of the reliability analysis. The procedure involves the reduction of the size of the vector of random variables before the calculation of failure probability. The objectives of this thesis are: 1.To use the available model reduction techniques in order to effectively reduce the size of the finite element model, and hence, compare the dynamic responses from such models. 2.Study of propagation of uncertainties in the reduced order/coupled stochastic finite element dynamic models. 3.Addressing the localized nonlinearities due to support gap effects in the built up structures, and also in cases of sudden change in soil behaviour under the footings. The irregularity in soil behaviour due to lateral escape of soil due to failure of quay walls/retaining walls/excavation in neighbouring site, etc. 4.To evolve a procedure for the reduction of size of the vector containing the random variables before the calculation of failure probability. In the reliability analysis of complex engineering structures, a very large number of the system parameters are considered to be random variables. Here the problem would be to reduce the number of random variables without sacrificing the accuracy of the reliability analysis. 5.To analyze the reduced nonlinear stochastic dynamic system (with phase space reduction), and effectively using the network pruning technique for the solution, and also to use filter theory (wavelet theory) for reducing the input earthquake record to save computational time and cost. It is believed that the techniques described provide highly useful insights into the manner structural uncertainties propagate. The cross-sectional area, length, modulus of elasticity and mass density of the structural components are assumed as random variables. Since both the random and design variables are expressed in a discretized parameter space, the stochastic sensitivity function can be modeled in a parallel way. The response of the structures in frequency domain is considered. This thesis is organized into seven chapters. This thesis deals with the reduced order models of the stochastic structural systems under deterministic/random loads. The Chapter 1 consists of a brief introduction to the field of study. In Chapter 2, an extensive literature survey based on the previous works on model order reduction and the response variability of the structural dynamic systems is presented. The discussion on parameter uncertainties, stochastic finite element method, and reliability analysis of structures is covered. The importance of reducing mechanical models for dynamic response variability, the systems with high-dimensional variables and reduction in random variables space, nonlinearity issues are discussed. The next few chapters from Chapter 3 to Chapter 6 are the main contributions in this thesis, on model reduction under various situations for both linear and nonlinear systems. After forming a framework for model reduction, local nonlinearities like support gaps in structural elements are considered. Next, the effect of reduction in number of random variables is tackled. Finally influence of network pruning and decomposition of input signals into low and high frequency parts are investigated. The details are as under. In Chapter 3, the issue of finite element model reduction is looked into. The generalized finite element analysis of the full model of a randomly parametered structure is carried out under a harmonic input. Different well accepted finite element model reduction techniques are used for FE model reduction in the stochastic dynamic system. The structural parameters like, mass density and modulus of elasticity of the structural elements are considered to be non-Gaussian random variables. Since the variables considered here are strictly positive, the probabilistic distribution of the random variables is assumed to be lognormal. The sensitivities in the eigen solutions are compared. The response statistics based on response of models in frequency domain are compared. The dynamic responses of the full FE model, separated into real and imaginary parts, are statistically compared with those from reduced FE models. Monte Carlo simulation is done to validate the analysis results from SFEM. In Chapter 4, the problem of coupling of substructures in a large and complex structure, and FE model reduction, e.g., component mode synthesis (CMS) is studied in the stochastic environment. Here again, the statistics of the response from full model and reduced models are compared. The issues of non-proportional damping, support gap effects and/local nonlinearity are considered in the stochastic sense. Monte Carlo simulation is done to validate the analysis results from SFEM. In Chapter 5, the reduction in size of the vector of random variables in the reliability analysis is attempted. Here, the relative entropy/ K-L divergence/mutual information, between the random variables is considered as a measure for ranking of random variables to study the influence of each random variable on the response/reliability of the structure. The probabilistic distribution of the random variables is considered to be lognormal. The reliability analysis is carried out with the well known Bucher and Bourgund algorithm (1990), along with the probabilistic model reduction of the stochastic structural dynamic systems, within the framework of response surface method. The reduction in number of random variables reduces the computational effort required to construct an approximate closed form expression in response surface approach. In Chapter 6, issues regarding the nonlinearity effects in the reduced stochastic structural dynamic systems (with phase space reduction), along with network pruning are attempted. The network pruning is also adopted for reduction in computational effort. The earthquake accelerogram is decomposed using Fast Mallat Algorithm (Wavelet theory) into smaller number of points and the dynamic analysis of structures is carried out against these reduced points, effectively reducing the computational time and cost. Chapter 7 outlines the contributions made in this thesis, together with a few suggestions made for further research. All the finite element codes were developed using MATLAB5.3. Final pages of the thesis contain the references made in the preparation of this thesis.

<p>Enligt Standish Group är det endast cirka 35 % av alla systemutvecklingsprojekt som avslutas på ett lyckat sätt när det gäller tid, budget och resurser. Inom systemutveckling är fastprisprojekt, där systemets kostnad är förbestämd, allt mer populärt. Dynamic Systems Development Method (DSDM) är en modell för utveckling som fokuserar på fasta resurser och tid med funktionalitet som den flexibla variabeln. Syftet med den här uppsatsen är att se om man kan driva fastprisprojekt med en modell som DSDM på ett sätt som gör det till en bra lösning för både beställare och leverantör.</p><p>Min slutsats är att det största problemet med DSDM är att få beställaren att godkänna den som projektmodell. Ett annat stort problem är att många projekt med DSDM blir stressiga eftersom tiden är fast. Flexibiliteten med funktionaliteten räcker med andra ord inte till. Önskvärda förbättringar inom DSDM är att ge mer underlag för hur man skall få en ny beställare att godkänna modellen. Dessutom att tillhandahålla guidelines för hur man kan hantera ett projekt med många och detaljerade krav. En annan viktig faktor som måste förbättras är hur man får projekt med DSDM att bli mindre stressiga.</p><p>DSDM är en modell som uppskattas av dem som har erfarenhet av den och som anses resultera i lyckade projekt, för både beställare och leverantör. Mina slutsatser är därför att DSDM kan fungera bra men att det ställer höga krav på projektet. Både beställare och leverantör måste vara engagerade. Beställaren måste kunna prioritera sina krav och räkna med att en del funktionalitet inte kommer med. Dessutom måste det finnas stor användarinvolvering och projektgruppen måste ha beslutsmandat.</p>

Contemporary theories frame emotion as an intra-personal system comprised of subcomponents such as experience, expressive behaviors, and physiology that interact over time to give rise to emotional episodes. Emotional episodes occur in the context of a social interaction or an ongoing relationship making it important to also conceptualize the inter-personal emotion system in which the subcomponents of the emotional response interact not only within the individual but across the partners as well. Emotion theory has been constricted by a dominant linear information processing metaphor and has not yet fully embraced a dynamic systems approach integrating concepts of open, self-organizing systems to interpersonal emotion regulation processes. To address these limitations, this study examined the emergence of structure and patterns in real-time dyadic interactions between pairs of female strangers where one partner is purposefully regulating her emotional responding. One member of each dyad was randomly assigned to suppress, positively reappraise, or act normally during an interaction task. Three subcomponents of emotion were examined (expressive behaviors, experience, and physiology) along with three features of dynamic systems (attractor basins, flexibility/entropy, and physiological linkage). Results indicate differences in the emergence of structure and patterns in real-time dyadic interactions that varies by emotional responding type. Suppression dyads were characterized by a non-emotional response attractor, reduced behavioral flexibility, stronger physiological linkage as compared to control and reappraisal dyads. Reappraisal dyads expressed more positive emotions during the interaction than control or suppression dyads, and reappraisal partners showed evidence of positive physiological linkage with the reappraiser. In conclusion, structural patterns do differ by emotion regulation condition indicating the importance of intrapersonal phenomena on the emergence of interpersonal system dynamics.

Approved for public release; distribution is unlimited / The development of a dynamic computational model capable of predicting, with the requisite design certainty, the transient thermal response of jet vane thrust control systems has been undertaken. The modeling and simulation procedures utilized are based on the concept that the thermal processes associated with jet vane operation can be put into a transfer function form commonly found in the discipline of automatic controls. Well established system identification methods are employed to formulate and verify the relationships between the various gains and frequencies of the transfer function model and experimental data provided by Naval Weapons Center, China Lake. / http://archive.org/details/modelingofjetvan00hatz / Lieutenant, United States Navy

Thesis advisor: Jeffrey Bloechl / This dissertation takes up Maurice Merleau-Ponty's unfinished project of developing an ontology of nature whose concepts are drawn from the phenomenon of life, rather than from human techne. I argue that the question of life has been hopelessly obscured by the collapse, in the Modern era, of the distinction between nature and artifice. We cannot hope to understand the difference between life and non-life until we understand the difference between the living body and the machine. Merleau-Ponty's constant aim was to show that the living body is not a blind mechanism, and that the body has its own endogenous sense which is not projected onto it by a disembodied consciousness. Central to these efforts were the phenomena of learning and development, and the concept of form or Gestalt. Development is what distinguishes the living body, which is an open-ended process of becoming, from the machine, whose possibilities are determined in advance by its creator. In order to conceptualize the phenomenon of development, Merleau-Ponty appropriated from psychology the concept of form (Gestalt): a dynamic, self-organizing whole that cannot be decomposed into independent parts. Where the conception of nature as mechanism implies that everything is determined in advance, Merleau-Ponty's conception of nature as Gestalt allows for the genesis of genuinely new phenomena through nature's own self- organizing movement. We would thus be able to understand the genesis of sense in nature as a process of morphogenesis--the genesis of form. However, Merleau-Ponty struggled to clarify the ontological status of form. He lacked the conceptual resources to explain form in its own terms, rather than by contrast with the decomposable wholes of human artifice. This dissertation attempts to locate these conceptual resources in the science of complexity that has emerged since Merleau- Ponty's death, and whose descriptions of complex systems are uncannily anticipated in Merleau-Ponty's writings. I take from this new science the conception of form as asymmetry or difference, and of morphogenesis as symmetry-breaking or self-differentiation. In order to investigate how meaning emerges out of form, I turn to recent work in biology and psychology that applies the concept of symmetry-breaking to the phenomena of anatomical growth and motor development. By studying the development of the living body and its behavior, I show how nature articulates itself into perceiver and perceived. In the movement of the living body, form folds back upon itself, giving rise to a new kind of meaning: a pre-reflective, motor significance that is neither mechanism nor mental representation. In Chapter One, I distinguish the living body from a machine or artifact by distinguishing between manufacturing and growth. This distinction, which seemed obvious to the Ancients, has been obscured by Modern science's pivotal decision to treat nature as if it were a product of human artifice. This decision has committed us to an atomistic ontology, which takes nature to be a synthetic whole composed of mutually indifferent parts. However, this ontology faces a basic problem, which I call the problem of form: how to explain the synthesis of indifferent atoms into the complex, harmonious wholes we observe in nature, without appealing to an intelligent designer. Nowhere is this problem more acute than in the phenomenon of anatomical development or embryogenesis. I argue that biology has been unable to explain this phenomenon in mechanical or atomistic terms: the Neo-Darwinist view of the living body as a synthetic whole determined in advance by a genetic blueprint or program has succeeded not by explaining development, but rather by ignoring it. In Chapter Two, I argue that the problem of form--and of living form in particular--can only be resolved by abandoning our atomistic ontology, and with it our synthetic understanding of form as a shape imposed on an indifferent material. Recent developments in the science of complexity have yielded a new definition of form as asymmetry or difference. On this view, the genesis of form in nature is not the synthesis of wholes out of pre-existing parts, but the self-differentiation of wholes into parts through symmetry-breaking. In order to understand how natural wholes become less symmetrical over time, I introduce three further concepts from the science of complexity: nonlinearity, stability, and instability. With these concepts in hand, I return to the problem of embryogenesis, in order to show how complex living forms can develop reliably and robustly without being determined in advance by a design or program. In Chapter Three, I turn from anatomical development to the development of behavior, in order to see how the genesis of form becomes a genesis of sense. I begin by criticizing three mechanistic theories of behavior--Behaviorism, Cognitivism, and Connectionism--which suffer from the same problem of form that plagues mechanistic theories of anatomical development. Behavior grows like an organ: by symmetry-breaking, not by synthesis. Learning is not a matter of association, but of differentiation: the perception of increasingly subtle asymmetries in the body's environment through increasingly asymmetrical movements. It is the world that teaches the organism how to move--but a world that is only revealed to the organism by its own movements. Thus the living body and its world grow together dialectically, each driving the other to become more determinate through its own increasing determinacy. / Thesis (PhD) — Boston College, 2012. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Philosophy.

O método aqui desenvolvido, bem como as aplicações feitas ao estudo de sistemas clássicos da dinâmica não-linear, tiveram por objetivo construir uma ferramenta adequada à descrição das características globais de fenômenos complexos da dinâmica não-linear. Uma característica típica da descrição probabilística do comportamento dinâmico de um sistema é sua expressão em termos da evolução temporal da função densidade de probabilidade dos estados, que é governada por uma equação diferencial linear, em contraste com a descrição temporal convencional, utilizada em dinâmica não-linear. Enquanto esta última, comumente dita determinística, exibe fenômenos tais como instabilidades, bifurcações, sensibilidade a condições iniciais etc, a descrição probabilística se manifesta, quando o sistema dinâmico detém propriedades de ergodicidade, em uma evolução não-reversível da função densidade de probabilidade em direção a um estado final invariante, mais especificamente tendendo ao equilíbrio global de um sistema linear. Este trabalho visa a aplicação da teoria probabilística da evolução de densidades de probabilidade em um problema de capotamento de veículos. Para isso, a teoria é descrita por meio de seus fundamentos e aplicada primeiramente em modelos clássicos da dinâmica não-linear, que, por serem bem estudados, podem comprovar a validade, bem como a extensão dessa forma de análise. / The method developed in this work, as well as its application in classical non-linear dynamics systems, had the main purpose of building a suitable tool in describing global complex phenomena of non-linear dynamics. A typical feature of the probabilistic approach of dynamics systems behavior is the ability to express it as a temporal probability density function evolution in terms of a linear evolution equation, which is ruled by a linear differential equation, as opposed to the regular temporal description used in non-linear dynamics. While the aforementioned description, also called deterministic, may face a variety of phenomena such as instabilities, bifurcation, high sensibility to initial conditions etc, in the probabilistic approach, as long as the dynamic system enjoys some ergodic properties, the probability density function will be driven irreversibly to a final invariant state, towards a global equilibrium of a linear system. This work consists in the application of probabilistic theory of density evolution in the problem of vehicle rollover subject to a certain maneuver. In order to accomplish that, all theory described is firstly applied to classical problems of nonlinear dynamics, since they have many established results, and as such, can validate and extend this sort of analysis for any dynamic system.

Neste trabalho analisamos o comportamento dinâmico de um modelo clássico e de um modelo quântico de spins na presença de um campo magnético externo. Para estudar a dinâmica de um sistema de spins clássico utilizamos um modelo de Ising bidimensional com interações entre spins primeiros vizinhos na direção vertical diferente daquelas entre spins primeiros vizinhos na horizontal. Através do formalismo da equação mestra, e considerando o processo estocático de Glauber dentro da aproximação de pares dinâmica, determinamos os diagramas de fases estacionários para o modelo na presença de campos magnéticos estáticos e oscilantes no tempo. Dependendo dos valores da razão entre os acoplamentos na horizontal e na vertical, da frequência e da amplitude do campo oscilante, obtemos diagramas de fases onde estão presentes os ordenamentos ferromagnético, paramagnético e antiferromagnético. Além disso, a transição entre as fases pode ser contínua ou descontínua dependendo dos valores dos parâmetros. O modelo também pode apresentar um comportamento tricrítico. O modelo de Ising em um campo transverso unidimensional à temperatura nula foi o modelo escolhido para estudarmos a resposta de sistemas quânticos de spins sujeitos a campos magnéticos que oscilam periodicamente no tempo. Usamos a aproximação de campo médio e simulações de Monte Carlo para determinar a linha de transição contínua entre as fases ferromagnética e paramagnética presentes no diagrama de fases dinâmico do modelo. / In this work we have analized the dynamical behavior of a classical and of a quantum spin model subject external magnetic fields. For a better understanding of the dynamics of a classical spin system we have chosen a two-dimensional Ising model with interactions between first neighbors in the horizontal direction different from that of the vertical direction. By using the master-equation formalism and taking the stochastic Glauber process, within the dynamical pair approximation, we have determined the stationary phase diagrams of the model for static and oscillating magnetic fields. Depending on the values of the ratio between the horizontal and vertical couplings, the frequency and the amplitude of the time dependent field, we have obtained phase diagrams where the ferromagnetic, paramagnetic and antiferromagnetic phases are present. Besides, the transition between these phases can be continuous or discontinuous depending on the values of the parameters. The model may display also a tricritical behavior. We have also chosen the transverse Ising model in one dimension at zero temperature to study the response of the quantum spin systems subject to time dependent external fields. We have used the mean-field approximation and the Monte Carlo simulations to determine the continuous transition line between the ferromagnetic and paramagnetic phases.

Nas últimas décadas, vários sistemas de comunicação baseados em sincronismo caótico têm sido propostos na literatura como alternativa a sistemas de espalhamento espectral que melhoram o nível de privacidade na transmissão da mensagem. No entanto, devido à falta de robustez do sincronismo caótico, um pequeno nível de ruído ou uma simples imperfeição no canal é suficiente para impedir a comunicação. Neste trabalho, equalizadores adaptativos são utilizados para permitir a comunicação em um sistema de comunicação baseado em caos quando a resposta em frequência do canal não é ideal. São propostos algoritmos de equalização baseados em versões modificadas do algoritmo normalized least-mean-squares para a versão de tempo discreto do sistema de comunicação baseado no modelo de sincronismo de Wu e Chua. Para esses algoritmos, é calculado o intervalo para a escolha do passo de adaptação para evitar a divergência. Como geradores de sinais caóticos (GSC), são utilizados os mapas de Hénon e de Ikeda e, para a codificação da mensagem, são consideradas duas funções, sendo uma baseada na multiplicação da mensagem por um dos estados do GSC e a outra baseada na soma da mensagem com um dos estados do GSC. Os resultados de simulação indicam que os algoritmos propostos são capazes de equalizar o canal de comunicação e permitir o sincronismo caótico em diferente cenários. / In the last decades, many communication systems applying synchronism of chaotic systems have been proposed as an alternative spread spectrum modulation that improves the level of privacy in data transmission. However, due to the lack of robustness of chaos synchronization, even a low level of noise or minor channel imperfections are enough to hinder communication. In this work, adaptive equalizers are used to enable chaotic synchronization when the communication channel is not ideal. Adaptive equalization algorithms are proposed based on a modified version of the normalized least-mean-squares algorithm, considering the discrete-time version of the communication system based on Wu and Chuas synchronization model. For these algorithms, the interval for the choice of the step-size is computed, in order to avoid divergence. The Hénon and the Ikeda maps are used as chaotic signal generators (CSG) and two functions are considered to encode the message, one based on the multiplication of the message by one of the states of the CSG and the other based on the addition of the message to one of the states of the CSG. Simulation results show that the proposed algorithms can successfully equalize the channel in different scenarios.

Alguns métodos aproximados são sugeridos na literatura relacionada para encontrar a resposta de sistemas com amortecimento não-proporcional. Muitas vezes procura-se estabelecer um critério para aproximar o amortecimento não-proporcional por um modelo de amortecimento proporcional. Neste trabalho foram utilizadas simulações de modelos dinâmicos com três graus de liberdade, com amortecimento não proporcional, a fim de analisar os valores obtidos para as freqüências naturais, estimados a partir dos autovalores resultantes desses modelos. Os cálculos das freqüências naturais e dos amortecimentos modais foram feitos admitindo-se a validade das relações entre estes parâmetros e os autovalores do problema como são bem conhecidas no caso do amortecimento proporcional. Observa-se que, para o caso de amortecimento não-proporcional, este procedimento pode levar a erros significativos na avaliação destes parâmetros. Nos problemas simulados é possível quantificar os erros nas avaliações das freqüências naturais, sendo significativos para fatores de amortecimentos altos. Observa-se que para os fatores de amortecimento não é possível quantificar estes erros, sendo que seus valores são apenas aproximações baseadas na teoria de amortecimento proporcional. Este trabalho apresenta dados que possibilitam uma discussão sobre as diferenças encontradas entre os valores das freqüências naturais e os valores estimados pelas expressões clássicas do amortecimento proporcional. / Some approximate methods are suggested in the related literature to find the output of mechanical systems with non-proportional damping. Often they try to establish a criterion that approximates the non-proportional damping to proportional damping model. In this work, stimulations of dynamics models of three degree of freedom with non-proportional damping were used to examine the values of natural frequencies, estimated from the eigenvalues obtained by these models. The calculations of natural frequencies and modal damping ratio were performed assuming the validity of the relationship between these parameters and the well known eigenvalues of the problem in the proportional damping case. In the simulated problems is possible to quantify the errors in the evaluations of the natural frequencies and this errors are significant for the case where the damping factors are high. It is observed that for the damping factors it is not possible to quantify these errors, and their magnitudes are only approximations based on the theory of proportional damping. This work presents data which enables a discussion about the differences between the magnitude of natural frequencies and the magnitude estimated by the classic equations of proportional damping.