Η ευαισθησία των συστημάτων είναι ένα σημαντικό θέμα της Θεωρίας Συστημάτων, το οποίο καλύπτεται σε εισαγωγικό επίπεδο με αυτή την εργασία. Η ευαισθησία αφορά τις διαφορές ανάμεσα στο πραγματικό σύστημα και στο μαθηματικό μοντέλο: αν κάποιες παράμετροι διαφέρουν αρκετά ανάμεσα στο πραγματικό σύστημα και στο μαθηματικό μοντέλο και η συμπεριφορά του συστήματος εξαρτάται κατά μεγάλο βαθμό από αυτές τις παραμέτρους, τότε η χρησιμότητα του μαθηματικού μοντέλου θα είναι πολύ μικρή αν δεν γνωρίζουμε ταυτόχρονα την παραμετρική ευαισθησία του συστήματος, δηλαδή την επίδραση των μεταβολών των παραμέτρων πάνω στην δυναμική συμπεριφορά του συστήματος. Βασικό ρόλο παίζει η προσομοίωση των εξισώσεων ευαισθησίας κατάστασης. Καθορίζουμε αρχικά τις εξισώσεις ευαισθησίας κατάστασης για παραμέτρους τύπου α και δείχνουμε ότι οι συναρτήσεις ευαισθησίας κατάστασης ενός συνεχούς συστήματος με χρονικά αμετάβλητες παραμέτρους καθορίζονται πάντα από ένα γραμμικό σύστημα διαφορικών εξισώσεων με μηδενικές αρχικές συνθήκες. Στην συνέχεια θα επεκταθούμε και στην εύρεση των συναρτήσεων ευαισθησίας κατάστασης για την περίπτωση που έχουμε παραμέτρους τύπου β και θα δούμε ότι και εδώ οι εξισώσεις ευαισθησίας κατάστασης είναι πάντα γραμμικές και οι αρχικές συνθήκες είναι ή μηδέν ή μονάδα. Στη συνέχεια προχωράμε στην εύρεση των συναρτήσεων ευαισθησίας κατάστασης για την περίπτωση που έχουμε παραμέτρους τύπου λ, αφού δούμε πρώτα το πότε μπορούμε να χρησιμοποιήσουμε το μειωμένο ονομαστικό μοντέλο. Επί πλέον, εξετάζουμε εν συντομία και τον καθορισμό των εξισώσεων ευαισθησίας εξόδου. Για την περίπτωση που έχουμε να μελετήσουμε και να συγκρίνουμε την παραμετρική ευαισθησία συστημάτων ανοικτού και κλειστού βρόχου καθώς επίσης και στην σύνθεση συστημάτων "αναίσθητων" σε παραμετρικές μεταβολές, είναι αναγκαίο να έχουμε έναν ορισμό ευαισθησίας που να είναι ανεξάρτητος από την μορφή του σήματος εισόδου, αλλά να εξαρτάται μόνο από την δομή του συστήματος. Αυτή η απαίτηση ικανοποιείται με τους ορισμούς ευαισθησίας στο πεδίο συχνότητας, οι οποίοι βασίζονται στην συνάρτηση μεταφοράς ή στον πίνακα μεταφοράς του συστήματος. Εξετάζουμε τη συνάρτηση ευαισθησίας του Bode, τη συνάρτηση ευαισθησίας του Horowitz και τη συγκριτική συνάρτηση ευαισθησίας των Perkins και Cruz. Η τελευταία μπορεί να γενικευθεί και σε μη γραμμικά, χρονικά μεταβαλλόμενα συστήματα. / The sensitivity of systems is an important theme of Systems Theory, which is covered to an introductory level in this work. The sensitivity concerns differences between the real system and the mathematical model: if some parameters are quite different between the real system and the mathematical model and the behavior of the system depends strongly on these parameters, the utility of the mathematical model will be very little if we do not know both the parametric sensitivity of the system, i.e. the effect of changes in parameters on the dynamic behavior of the system. A key role is played by simulating the state sensitivity equations. First we determine the state of sensitivity equations for parameters of type a and show that the state of sensitivity functions of a continuous system with time invariant parameters are always determined by a linear system of differential equations with zero initial conditions. Then we expand and find the state sensitivity functions for the case where we have parameters of type b and we see that here the situation sensitivity equations are always linear and the initial conditions are zero. Then we move on finding state sensitivity functions for the type lambda parameters, after we look when the reduced nominal model can use. Moreover, we look briefly at the output sensitivity equations. In case we have to study and compare the parametric sensitivity of open and closed-loop systems as well as in the synthesis systems "unconscious" to parametric changes, it is necessary to have a definition of sensitivity that is independent of the input signal format, but can depend only on the structure of the system. This requirement is satisfied by the definitions of sensitivity in the frequency domain, which are based on the transfer function or the system operator panel. We examine the sensitivity function of Bode, the sensitivity function of Horowitz and the comparative context sensitivity of Perkins and Cruz. The latter can be generalized to nonlinear, time-varying systems.

The purpose of this study was to compare the coach-athlete interaction structures of two competitive youth synchronized swimming teams, one more successful with regard to athletes’ performance and personal development than the other. This comparison was conducted through the first application of state space grid (SSG) observational methodology (Hollenstein, 2007; Lewis, Lamey, & Douglas, 1999) in field-based sport psychology research. Both teams (two head coaches and 17 athletes in total) were observed over multiple training sessions. Both coach and athlete behaviour was coded continuously for the duration of each training session. Measures of coach athlete interaction structure, based on dynamic systems concepts, were derived from these coded behaviours and compared between teams. Results revealed significant differences between the two teams on measures of interaction variability, behavioural content patterns, and the sequencing of coach behaviours. The more successful team was characterized by less variable, more patterned interactions between coaches and athletes. This patterning took the form of more individualized technical and positive reinforcement feedback information and significantly less use of negative feedback by the head coach, interspersed with substantial periods of silent observation. The athletes of the more successful team more actively acknowledged the receipt of this feedback from their coach. The sequencing of coach behaviours was more patterned for the coach of the more successful team, with heavy emphasis on the pairing of technical correction and positive reinforcement statements. The findings suggest that a respectful, deliberate pattern of coach-athlete interaction may be associated with youth sport environments producing more positive performance and personal development outcomes for athletes. / Thesis (Master, Kinesiology & Health Studies) -- Queen's University, 2009-12-16 14:46:55.016

In this thesis a model involving two coupled nonlinear PDEs is developed to study instability of a two-component metal film due to horizontal electric field and in a high-temperature environment similar to operational conditions of integrated circuits. The proposed model assumes the anisotropies of the diffusional mobilities for two atomic species, and negligible stresses in the film. The purpose of the modeling is to describe and understand the time-evolution of the shape of the film surface. Toward this end, the linear stability analysis (LSA) of the initially planar film surface with respect to small shape perturbations is performed. Such characteristics of the instability as the perturbation growth rate omega and the cut-off wave number are studied as functions of key physical parameters.

In this work, we introduce several novel approaches to feedback controller design, known collectively as the “Robust Bode” methods, which adapt classical control principles to a modern robust control (H∞) framework. These methods, based on specially modified Bode diagrams extend familiar frequency-domain controller design techniques to linear and nonlinear, single–input/single– output (SISO) and multi–input/multi–output (MIMO) systems with parametric and/or unstructured uncertainties. In particular, we introduce the Contoured Robust Controller Bode (CRCBode) plots which show contours (level-sets) of a robust metric on the Bode magnitude and phase plots of the controller. An iterative loop shaping design procedure is then employed in an attempt to eliminate all intersections of the controller frequency response with certain forbidden regions indicating that a robust stability and performance criteria is satisfied. For SISO systems a robust stability and performance criterion is derived using Nyquist arguments leading to the robust metric used in the construction of the CRCBode plots. For open-loop unstable systems and for non-minimum phase systems the Youla parametrization of all internally stabilizing controllers is used to develop an alternative Robust Bode method (QBode). The Youla parametrization requires the introduction of state-space methods for coprime factorization, and these methods lead naturally to an elegant connection between linear-quadratic Gaussian (LQG) optimal control theory and Robust Bode loop-shaping controller design. Finally, the Robust Bode approach is extended to MIMO systems. Utilizing a matrix norm based robustness metric on the MIMO CRCBode plots allows cross-coupling between all input/output channels to be immediately assessed and accounted for during the design process, making sequential MIMO loop-shaping controller design feasible.

The aim of this thesis is to narrow the gap between two different control techniques: the continuous control and the discrete event control techniques DES. This gap can be reduced by the study of Hybrid systems, and by interpreting as Hybrid systems the majority of large-scale systems. In particular, when looking deeply into a process, it is often possible to identify interaction between discrete and continuous signals. Hybrid systems are systems that have both continuous, and discrete signals. Continuous signals are generally supposed continuous and differentiable in time, since discrete signals are neither continuous nor differentiable in time due to their abrupt changes in time. Continuous signals often represent the measure of natural physical magnitudes such as temperature, pressure etc. The discrete signals are normally artificial signals, operated by human artefacts as current, voltage, light etc.Typical processes modelled as Hybrid systems are production systems, chemical process, or continuos production when time and continuous measures interacts with the transport, and stock inventory system. Complex systems as manufacturing lines are hybrid in a global sense. They can be decomposed into several subsystems, and their links. Another motivation for the study of Hybrid systems is the tools developed by other research domains. These tools benefit from the use of temporal logic for the analysis of several properties of Hybrid systems model, and use it to design systems and controllers, which satisfies physical or imposed restrictions.This thesis is focused in particular types of systems with discrete and continuous signals in interaction. That can be modelled hard non-linealities, such as hysteresis, jumps in the state, limit cycles, etc. and their possible non-deterministic future behaviour expressed by an interpretable model description. The Hybrid systems treated in this work are systems with several discrete states, always less than thirty states (it can arrive to NP hard problem), and continuous dynamics evolving with expression: with Ki ¡ Rn constant vectors or matrices for X components vector. In several states the continuous evolution can be several of them Ki = 0.In this formulation, the mathematics can express Time invariant linear system. By the use of this expression for a local part, the combination of several local linear models is possible to represent non-linear systems. And with the interaction with discrete events of the system the model can compose non-linear Hybrid systems.Especially multistage processes with high continuous dynamics are well represented by the proposed methodology. Sate vectors with more than two components, as third order models or higher is well approximated by the proposed approximation. Flexible belt transmission, chemical reactions with initial start-up and mobile robots with important friction are several physical systems, which profits from the benefits of proposed methodology (accuracy).The motivation of this thesis is to obtain a solution that can control and drive the Hybrid systems from the origin or starting point to the goal. How to obtain this solution, and which is the best solution in terms of one cost function subject to the physical restrictions and control actions is analysed. Hybrid systems that have several possible states, different ways to drive the system to the goal and different continuous control signals are problems that motivate this research.The requirements of the system on which we work is: a model that can represent the behaviour of the non-linear systems, and that possibilities the prediction of possible future behaviour for the model, in order to apply an supervisor which decides the optimal and secure action to drive the system toward the goal.Specific problems can be determined by the use of this kind of hybrid models are: - The unity of order.- Control the system along a reachable path.- Control the system in a safe path.- Optimise the cost function.- Modularity of controlThe proposed model solves the specified problems in the switching models problem, the initial condition calculus and the unity of the order models. Continuous and discrete phenomena are represented in Linear hybrid models, defined with defined eighth-tuple parameters to model different types of hybrid phenomena. Applying a transformation over the state vector : for LTI system we obtain from a two-dimensional SS a single parameter, alpha, which still maintains the dynamical information. Combining this parameter with the system output, a complete description of the system is obtained in a form of a graph in polar representation.Using Tagaki-Sugeno type III is a fuzzy model which include linear time invariant LTI models for each local model, the fuzzyfication of different LTI local model gives as a result a non-linear time invariant model. In our case the output and the alpha measure govern the membership function.Hybrid systems control is a huge task, the processes need to be guided from the Starting point to the desired End point, passing a through of different specific states and points in the trajectory. The system can be structured in different levels of abstraction and the control in three layers for the Hybrid systems from planning the process to produce the actions, these are the planning, the process and control layer.In this case the algorithms will be applied to robotics ¡V a domain where improvements are well accepted ¡V it is expected to find a simple repetitive processes for which the extra effort in complexity can be compensated by some cost reductions. It may be also interesting to implement some control optimisation to processes such as fuel injection, DC-DC converters etc.In order to apply the RW theory of discrete event systems on a Hybrid system, we must abstract the continuous signals and to project the events generated for these signals, to obtain new sets of observable and controllable events. Ramadge & Wonham¡¦s theory along with the TCT software give a Controllable Sublanguage of the legal language generated for a Discrete Event System (DES). Continuous abstraction transforms predicates over continuous variables into controllable or uncontrollable events, and modifies the set of uncontrollable, controllable observable and unobservable events. Continuous signals produce into the system virtual events, when this crosses the bound limits. If this event is deterministic, they can be projected. It is necessary to determine the controllability of this event, in order to assign this to the corresponding set, , controllable, uncontrollable, observable and unobservable set of events.Find optimal trajectories in order to minimise some cost function is the goal of the modelling procedure. Mathematical model for the system allows the user to apply mathematical techniques over this expression. These possibilities are, to minimise a specific cost function, to obtain optimal controllers and to approximate a specific trajectory.The combination of the Dynamic Programming with Bellman Principle of optimality, give us the procedure to solve the minimum time trajectory for Hybrid systems. The problem is greater when there exists interaction between adjacent states.In Hybrid systems the problem is to determine the partial set points to be applied at the local models. Optimal controller can be implemented in each local model in order to assure the minimisation of the local costs. The solution of this problem needs to give us the trajectory to follow the system. Trajectory marked by a set of set points to force the system to passing over them.Several ways are possible to drive the system from the Starting point Xi to the End point Xf. Different ways are interesting in: dynamic sense, minimum states, approximation at set points, etc. These ways need to be safe and viable and RchW. And only one of them must to be applied, normally the best, which minimises the proposed cost function. A Reachable Way, this means the controllable way and safe, will be evaluated in order to obtain which one minimises the cost function.Contribution of this work is a complete framework to work with the majority Hybrid systems, the procedures to model, control and supervise are defined and explained and its use is demonstrated. Also explained is the procedure to model the systems to be analysed for automatic verification.Great improvements were obtained by using this methodology in comparison to using other piecewise linear approximations. It is demonstrated in particular cases this methodology can provide best approximation.The most important contribution of this work, is the Alpha approximation for non-linear systems with high dynamics While this kind of process is not typical, but in this case the Alpha approximation is the best linear approximation to use, and give a compact representation.

A useful model of spiritual development in the public educative care of children must: specify the meaning and nature of spirituality; clarify its relationship to an underlying ontology; identify in what sense spirituality is developmental; be consistent with a justifiable paradigm of human development; explain the role and status of such spiritual development with a secular system of educative care; and specify practical implications flowing from these matters. Using narrative criticism within an evangelical framework, the biblical descriptions of spirituality and childhood were critically examined as a basis for such a model. Biblical spirituality was developmental and was identified with encounters, usually naturally mediated, between human spirits and God's Spirit, and spirits which alienate from God's Spirit. All children, without qualification of belief, community, rite or age, were identified as spirits who share a special relationship with God's Spirit both ontologically and experientially. Biblical childhood was not defined chronologically but functionally by inability to take responsibility for one's own spiritual life because of openness to God's and other spirits. Principles of 'magician systems' in Dynamic Systems Theory parallel phenomena of human development and those commonly designated as spiritual. Consequently, a dynamic model of spiritual development is proposed which is consonant with biblical teaching and grounded in an established scientific paradigm. This indicates that spirituality is an inescapable aspect of any educative care setting or system and need not be introduced as though children lack it. Spiritually salient aspects of educative care will lead children to spiritual encounters which are derivative of a positive life affirming principle or fundamentally destructive and alienating. These aspects encompass the spiritual ontology of the setting, the children, the personnel, the physical environment, the nature and quality of relationships, the curriculum, religious activities, the nurture provided, and the wider context, all of which are of spiritual moment.

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[pt] É considerado o problema da estabilidade de sistemas dinâmicos bilineares em ambiente estocástico. Após a apresentação de uma coletânea de resultados já existentes, são propostas novas condições de estabilidade para sistemas discretos utilizando o método direto de Lyapunov. Tais resultados são comparados com os já existentes. / [en] The stability of bilinear dynamic systems in a stochastic environment is considered, including a survey on this field. New conditions for stability of discrete systems using the direct method of Lyapunov are proposed. The results developed here are compared with chose in the current literature.

O presente trabalho, de fonética acústica, visa a investigar dois aspectos referentes ao desenvolvimento multilíngue, à luz da Teoria dos Sistemas Dinâmicos, Adaptativos Complexos (BECKNER et al., 2009; DE BOT et al., 2013, SILVA, 2014): i. a (multi) direcionalidade da transferência vocálica em falantes plurilíngues de espanhol como língua materna (L1), inglês como segunda língua (L2) e português como segunda língua (L2) ou terceira língua (L3) e ii. a premissa de que uma mudança em qualquer parte do sistema pode gerar alteração nas outras partes do(s) sistema(s) linguístico(s). Com vistas a investigar o primeiro aspecto, foi conduzido um estudo transversal, em que foram realizados dois tipos de análises. A análise do tipo inter-grupo contou com cinco grupos formados a fim de realizarmos as comparações entre os valores formânticos e de duração das produções vocálicas de cada grupo. Para o cumprimento de tal objetivo, o primeiro grupo foi formado por 5 monolíngues do português brasileiro, residentes em Porto Alegre, RS, para que servisse de grupo controle, a fim de prover os valores formânticos e padrões de duração referentes às vogais do sistema-alvo, o português. O segundo grupo contou com 5 falantes monolíngues de espanhol (variedade rio-platense), residentes na Argentina, e também serviu como controle para a coleta de valores de formantes e de duração para a comparação com as produções dos falantes multilíngues nativos de espanhol que possuem a L2 (inglês ou português) ou a L2 e a L3 (inglês e português) A comparação deste grupo de participantes monolíngues com os participantes dos grupos descritos a seguir possibilitou a verificação de alterações nos valores formânticos e de duração da L1 (espanhol rio-platense), com base no argumento de que os participantes que dispõem de outros sistemas linguísticos apresentam diferenças formânticas e temporais das vogais dos monolíngues argentinos. O terceiro grupo, por sua vez, foi composto por 5 falantes bilíngues de espanhol (variedade rio-platense) como língua materna e português como L2. O quarto grupo foi composto por 5 falantes de espanhol (variedade rio-platense) como L1, inglês como L2 e português como L3, o que possibilitou a verificação do papel do inglês na aquisição do português por falantes de espanhol, quando as vogais do português (L2) desses aprendizes foram comparadas com as dos aprendizes do grupo anterior, que possuem o português, mas não o inglês. Ambos os grupos apresentaram um período de residência no Brasil de, no mínimo, 3 anos.O quinto grupo foi composto por 5 falantes de espanhol (variedade rio-platense) como L1 e aprendizes de inglês como L2, residentes na Argentina. Em relação ao nível de proficiência desses aprendizes em inglês, foi realizado o teste de nivelamento de Oxford (Oxford Online Placement Test, PURPURA, 2007), para que os aprendizes deste grupo e os aprendizes trilíngues (conforme descrição acima) apresentassem o mesmo grau de proficiência em língua inglesa A comparação das vogais do inglês (L2) dos participantes do quinto grupo, que não possuem o português (L3), com as vogais em inglês (L2) dos participantes do quarto grupo anterior, que possuem o português (L3), possibilitou a análise quanto ao papel da L3 sobre a L2. Além desta análise inter-grupo, foi conduzida, também, uma descrição do tipo intra-grupo, que consistiu na descrição dos valores formânticos e de duração de todos os sistemas vocálicos de cada grupo de participantes, tomados individualmente, para que fossem verificadas as possíveis formações de categorias no novo sistema. Para os propósitos supracitados, cada grupo foi solicitado a ler uma lista de palavras nas línguas de seu conhecimento. Os resultados aqui encontrados, em consistência com a Teoria dos Sistemas Dinâmicos, a Teoria da Complexidade e a Teoria do Caos, indicam que a fala dos participantes, não somente nos sistemas de L2 e L3, mas também no próprio sistema de L1, sofre múltiplas alterações devido à interação com agentes internos e externos. Em adição, as formas vocálicas encontradas neste experimento se compõem como formas híbridas, que mesclam características de todos os sistemas linguísticos dos participantes. Em razão da gama de múltiplos fatores envolvidos neste processo de desenvolvimento do sistema linguístico, as análises individuais tomadas longitudinalmente parecem conter informações mais ricas do que as análises transversais. Assim, um estudo longitudinal é capaz de apontar mais do que o simples “retrato” ou estágio em que o aprendiz se encontra no momento da coleta Nesse sentido, conduziu-se o segundo estudo, de cunho longitudinal, que contou com instrução formal de base comunicativa e articulatória sobre os sons vocálicos presentes na L3, mas ausentes na L1. Através da instrução formal, visou-se a causar uma modificação acelerada no sistema fonético-fonológico de L3 do aprendiz, para se verificar se tal modificação ocasionaria efeitos sobre a L1 e a L2. O estudo contou com um aprendiz trilíngue falante do espanhol (variedade mexicana) como L1, inglês como L2 e português como L3. A instrução deu-se ao longo de 4 meses, com uma aula de 90 minutos por semana. As coletas tiveram o mesmo instrumento do estudo transversal, isto é, as listas de palavras nas três línguas referidas, e ocorreram anteriormente ao período de instrução, durante (a cada 4 semanas) e ao término da instrução formal, de modo a totalizar 5 coletas com o participante. Os achados deste estudo longitudinal evidenciaram que as alterações em um sistema como o português (L3), aceleradas pela instrução fornecida, causaram alterações na produção vocálica dos demais sistemas, devido à interconexão dos sistemas do falante multilíngue. As alterações ocorreram tanto em termos de valores formânticos quanto em termos de duração absoluta e relativa Considerando uma perspectiva dinâmica e complexa, esta pesquisa fundamenta-se na pressuposição de que é necessário rejeitar a noção unidirecional de transferência linguística. A partir de tais resultados, podemos afirmar que uma L2 deve ser considerada como um sistema híbrido, que carrega características tanto da L1 quanto da L3. A L3, sob essa perspectiva, carrega aspectos das L1 e da L2. Além disso, a própria L1, ainda que de forma mais moderada, sofre influência dos outros sistemas que se estabelecem neste espaço fonológico comum. É rejeitada, portanto, a noção de direção singular quanto à transferência das L1 e L2 na L3, de modo que se possa assumir, assim, uma transferência multidirecional. / This study, within acoustic phonetics, aims to address two aspects concerning multilingual development, under the Dynamic Complex-Adaptive System Theory (BECKNER et al., 2009; DE BOT et al., 2013, SILVA, 2014): (i) the multi-directionality of vowel transfer in the speech production of L1 Spanish speakers of English (L2) and Portuguese (L2/L3), and (ii) the assumption that some changes in a given language system may account for the co-ocurrence of changes in the other systems. Given the first aspect, a cross-sectional experiment was conducted, in which speech production data were collected from 5 groups in order to compare formant and vowel duration values among groups. This experiment tested the hypothesis that formant and vowel duration values would differ among groups due to the existence of additional systems. In order to do so, the first group had 5 Porto-Alegre monolingual Brazilian Portuguese speakers, in order to provide native formant and durational values of Southern Brazilian Portuguese vowels. The second group had 5 monolingual Riverplate Spanish speakers (from Argentina) and also served as a control group, in order to provide the formant and durational values of Riverplate Spanish vowels The vowel productions of these participants were compared to those produced by the participants who spoke English or Portuguese as L2/L3, as described as follows. This allowed us to test if bilingual and trilingual native speakers of Spanish (L1) would present altered vowel formant and duration values from those found in the productions by monolingual speakers of Spanish. The third group had 5 bilingual speakers of Riverplate Spanish (L1) and Portuguese (L2), and the fourth group consisted of 5 trilingual speakers of Riverplate Spanish (L1), English (L2), and Portuguese (L3). The comparison between the vowel systems of these two groups allowed for the investigation of the influence of English in the development of Portuguese by L1 Spanish speakers, considering that one group lacks the English system. Both groups of participants had a similar length of residence in Brazil. Finally, the fifth group consisted of 5 bilingual speakers of L1 Spanish and English (L2) who live in Argentina. The comparison between the English vowels produced by this group (whose participants do not speak Portuguese) and the fourth group (which has developed the Portuguese language) made it possible to explore the role of the L3 on the L2, in terms of formant values and duration With regard to proficiency in English, all participants in the fourth and fifth groups were required to take the Oxford Online Placement Test (PURPURA, 2007), which indicated that the participants presented an upper-intermediate or advanced level of proficiency in the target language. In addition, an intra-group analysis was conducted, in which the duration and frequency values of each one of the vowel systems produced by each group of participants were compared and analyzed, in order to test category formation in each new language system. For each purpose mentioned above, participants were asked to read a list of words in the languages spoken by them. Results show that the speech produced by the multilingual participants seems to be affected by the interaction with and among the other language systems, besides the fact that their L1 does not seem to reflect the monolingual L1 System. Besides, their target language shows productions that reflect hybrid forms, which merge characteristics from all systems involved. Our data confirm the complexity of the multilingual development process and corroborate the premises of a view of Language as a Complex, Adaptive System Following the tenets of Complex Adaptive System Theory, the second assumption investigated in this research follows the current theoretical framework that views that any change in the developmental process can modify all the other parts of the system. Due to a great number of factors involved in this process, individual analyses across time seem to reveal richer information about the language development process than the cross-sectional analyses do. For this reason, a longitudinal experiment seems to offer more than just a picture of the development process, as it rather presents a longer part of the process. Based on this premise, a Spanish L1 (Mexican variety) speaker of English (L2) who had been learning Portuguese (L3) in Porto Alegre in 2015 was taught a 4 month-course of a Portuguese phonetic syllabus which focused on the open vowels of the target systems [ε] and [ͻ] and their counterparts [e] and [o]. We aimed to verify if the development of Portuguese open vowels [ε] and [ͻ], which are not produced in their L1, would play a role in the development of the open vowels [ͻ, ε, æ, ɑ] in the L2 (English), as well as in [e] and [o], the mid vowels in their L1 (Spanish). Our investigation considered not only these vowels, but the development of the entire vowel system in each language Instruction consisted of a weekly 90-minute class and took place along 4 months. Recordings were conducted in the same way of the cross-sectional study, in which there were lists of words to be read in the three languages. The first recording was conducted before the period of instruction, the next three recordings were conducted after every four classes, and the fifth recording was conducted at the end of the experiment, totaling 5 recordings. The findings of the longitudinal study provided evidence to the premise that alterations in one system such as Portuguese (L3), which has been accelerated by formal instruction, may cause alterations in the production of the vowels of the other languages, due to the interrelation among the language systems of this multilingual speaker. Departing from a view of language as a Complex, Adaptive System, the findings in this research reject the unidirectional account of language transfer. Results suggest that the L2 system can be seen as a hybrid system, which carries characteristics from both the L1 and the L3. The L3, under this perspective, also carries aspects from the L1 and L2 systems. Besides, the L1, even being the most dominant language, seems to suffer some moderate influence from the L2 and the L3, as the three systems coexist in the same phonological setting. This considered, a view of multi-directional transfer is adopted.

Made available in DSpace on 2014-06-11T19:25:32Z (GMT). No. of bitstreams: 0 Previous issue date: 2007-07-02Bitstream added on 2014-06-13T18:53:38Z : No. of bitstreams: 1 ferro_l_me_rcla.pdf: 3692564 bytes, checksum: d242c88fdfc24677645cf32fa498c692 (MD5) / Neste trabalho construímos modelos de redes neurais artificiais recorrentes com dois, com quatro, com seis e com oito neurônios na tentativa de simular computacionalmente como os neurônios receptores olfativos dos vertebrados, em especial dos seres humanos, conseguem identificar e reconhecer as diferentes moléculas odoríferas (ou odorantes) transportadas pelo ar. Para isso, usamos uma rede que evolui de um sistema dinâmico caótico, na ausência de odorantes, para o não-caótico, quando do reconhecimento de um odor constituído, no máximo, de até três odorantes. / We built models of recurrent artificial neural networks with two, four, six and eight neurons in order to simulate, using computational simulation, the way vertebrate s olfactory neurons, in special the humans, identify and recognize different odoriferous molecules (or odorants) in the air. For that purpose, we used a network that evolves from a chaotic dynamic system, in the absence of odorants, to the non-chaotic, when it recognizes an odor that is made of, at most, three odorants.