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1
Wang, Z., Y. Sun, Wyk BJ van, G. Qi und Wyk MA van. „A 3-D four-wing attractor and its analysis“. Brazilian Journal of Physics, 2009. http://encore.tut.ac.za/iii/cpro/DigitalItemViewPage.external?sp=1001369.
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Abstract
In this paper, several three dimensional (3-D) four-wing smooth quadratic autonomous chaotic systems are
analyzed. It is shown that these systems have a number of similar features. A new 3-D continuous autonomous
system is proposed based on these features. The new system can generate a four-wing chaotic attractor with less
terms in the system equations. Several basic properties of the new system is analyzed by means of Lyapunov
exponents, bifurcation diagrams and Poincare maps. Phase diagrams show that the equilibria are related to the
existence of multiple wings.
2
Lowenberg, Mark H. „Application of bifurcation analysis to multiple attractor flight dynamics“. Thesis, University of Bristol, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.264065.
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3
Rosay, Sophie. „A statistical mechanics approach to the modelling and analysis of place-cell activity“. Thesis, Paris, Ecole normale supérieure, 2014. http://www.theses.fr/2014ENSU0010/document.
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Les cellules de lieu de l’hippocampe sont des neurones aux propriétés intrigantes, commele fait que leur activité soit corrélée à la position spatiale de l’animal. Il est généralementconsidéré que ces propriétés peuvent être expliquées en grande partie par les comporte-ments collectifs de modèles schématiques de neurones en interaction. La physique statis-tique fournit des outils permettant l’étude analytique et numérique de ces comportementscollectifs.Nous abordons ici le problème de l’utilisation de ces outils dans le cadre du paradigmedu “réseau attracteur”, une hypothèse théorique sur la nature de la mémoire. La questionest de savoir comment ces méthodes et ce cadre théorique peuvent aider à comprendrel’activité des cellules de lieu. Dans un premier temps, nous proposons un modèle de cellulesde lieu dans lequel la localisation spatiale de l’activité neuronale est le résultat d’unedynamique d’attracteur. Plusieurs aspects des propriétés collectives de ce modèle sontétudiés. La simplicité du modèle permet de les comprendre en profondeur. Le diagrammede phase du modèle est calculé et discuté en comparaison avec des travaux précedents.Du point de vue dynamique, l’évolution du système présente des motifs particulièrementriches. La seconde partie de cette thèse est à propos du décodage de l’activité des cellulesde lieu. Nous nous demandons quelle est l’implication de l’hypothèse des attracteurs surce problème. Nous comparons plusieurs méthodes de décodage et leurs résultats sur letraitement de données expérimentalesPlace cells in the hippocampus are neurons with interesting properties such as the corre-lation between their activity and the animal’s position in space. It is believed that theseproperties can be for the most part understood by collective behaviours of models of inter-acting simplified neurons. Statistical mechanics provides tools permitting to study thesecollective behaviours, both analytically and numerically.Here, we address how these tools can be used to understand place-cell activity withinthe attractor neural network paradigm, a theory for memory. We first propose a modelfor place cells in which the formation of a localized bump of activity is accounted for byattractor dynamics. Several aspects of the collective properties of this model are studied.Thanks to the simplicity of the model, they can be understood in great detail. The phasediagram of the model is computed and discussed in relation with previous works on at-tractor neural networks. The dynamical evolution of the system displays particularly richpatterns. The second part of this thesis deals with decoding place-cell activity, and theimplications of the attractor hypothesis on this problem. We compare several decodingmethods and their results on the processing of experimental recordings of place cells in afreely behaving rat
4
Villani, Gianluca. „Analysis of an Attractor Neural Network Model for Working Memory: A Control Theory Approach“. Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-260079.
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Working Memory (WM) is a general-purpose cognitive system responsible for temporaryholding information in service of higher order cognition systems, e.g. decision making. Inthis thesis we focus on a non-spiking model belonging to a special family of biologicallyinspired recurrent Artificial Neural Network aiming to account for human experimentaldata on free recall. Considering its modular structure, this thesis gives a networked systemrepresentation of WM in order to analyze its stability and synchronization properties.Furthermore, with the tools provided by bifurcation analysis we investigate the role of thedifferent parameters on the generated synchronized patterns. To the best of our knowledge,the proposed dynamical recurrent neural network has not been studied before froma control theory perspective.Arbetsminne är ett brett, övergripande kognitivt system som ansvarar för temporär informationslagringhos högre ordningens tänkande, såsom beslutsfattning. Denna masteravhandlingämnar sig åt att studera icke-spikande modeller tillhörande en speciell gren avbiologiskt inspirerade återkommande neuronnät, för att redogöra mänsklig experimentelldata för fenomenet free recall. Med avseende på dess modulära struktur, framför denna avhandlingen nätverkssystemsrepresentation av arbetsminne sådant att dess stabilitets- samtsynkroniseringsegenskaper kan granskas. Innebörden av olika systemparametrar av de genereradesynkroniseringsmönstren undersöktes genom användandet av bifurkationsanalys.Som vi förstår, har den föreslagna dynamiska återkommande neuronätet inte studerats frånett reglertekniskt perspektiv tidigare.
5
Doboli, Simona. „Latent Attractors: A Mechanism for Context-Dependent Information Processing in Biological and Artificial Neural Systems“. Cincinnati, Ohio : University of Cincinnati, 2001. http://www.ohiolink.edu/etd/view.cgi?ucin984613871.
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Israel, Haydi. „Comportement asymptotique de modèles en séparation de phases“. Thesis, Poitiers, 2013. http://www.theses.fr/2013POIT2308/document.
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Dans cette thèse, on étudie l'existence, l'unicité et la régularité des solutionsd'équation de type Cahn-Hilliard ainsi que son comportement asymptotiqueen termes d'existence de l'attracteur global et d'un attracteur exponentiel. Cetteéquation est considérée dans un domaine borné et régulier pour différents types denonlinéarités et de conditions au bord.D'abord, on étudie l'équation avec des conditions de type Dirichlet sur le bord etune nonlinéarité régulière. Après, on considère une perturbation du problème et ondémontre l'existence d'une famille robuste d'attracteurs exponentiels lorsque ε tendvers 0.Ensuite, on étudie l'équation avec des conditions dynamiques sur le bord. On considèretout d'abord une nonlinéarité régulière et on donne une étude théorique etnumérique. Après, on illustre ces résultats par des simulations numériques en dimensiondeux d'espace qui permettent d'étudier l'influence des différents paramètres.On termine par une étude du modèle considéré avec une nonlinéarité singulière quel'on approche par des fonctions régulières et on introduit une notion de solutionappropriéeThis thesis is devoted to the study of the existence, uniqueness andregularity of solutions for a Cahn-Hilliard type equation, as well as the asymptoticbehavior in terms of existence of the global attractor and of an exponential attractor.This equation is considered in a bounded and smooth domain under variousassumptions on the nonlinear terms and with different boundary conditions.We start by studying the equation with Dirichlet boundary conditions and a regularnonlinearity. Then, we consider a perturbation of the problem and we prove theexistence of a robust family of exponential attractors as ε tends to 0.For the equation endowed with dynamic boundary conditions, we first consider aregular nonlinearity and we treat the theoretical and numerical analysis. Then, weillustrate the results by numerical simulations in two space dimension which allow usto study the influence of different parameters. Finally, we treat the problem consideredwith a singular nonlinearity which is approximated by regular functions andwe give a suitable notion of solutions
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Křápková, Monika. „Dynamický model produkce polyhydroxyalkonoátů termofilní bakterií S. thermodepolymerans“. Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2021. http://www.nusl.cz/ntk/nusl-442582.
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Tato diplomová práce se zabývá rekonstrukcí dynamického modelu produkce polyhydroxyalkanoátů (PHA) termofilní bakterií Schlegelella thermodepolymerans. První kapitola poskytuje čtenářům krátký úvod do systémové biologie a matematické teorie grafů. Na ni navazuje druhá kapitola zabývající se různými přístupy v dynamickém modelování, včetně běžně používaných nástrojů pro dynamickou analýzu komplexních systémů. Třetí kapitola pak sleduje další pojmy a možnosti týkající se analýzy modelu. Následující kapitola se zaměřuje na metabolomiku a často používané laboratorní techniky a pátá kapitola je pak věnována polyhydroxyalkanoátům, zejména jejich chemické struktuře a vlastnostem. V kapitole šesté je navržen obecný booleovský model pro produkci PHA termofilními bakteriemi. Kapitola sedmá se poté zaměřuje na zdokonalení modelu se zaměřením na S. thermodepolymerans. Výsledný dynamický model je podroben analýze a výsledky jsou diskutovány.
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Erkursun, Nazife. „Convergence Of Lotz-raebiger Nets On Banach Spaces“. Phd thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/3/12612108/index.pdf.
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The concept of LR-nets was introduced and investigated firstly by H.P. Lotz in [27] and by F. Raebiger in [30]. Therefore we call such nets Lotz-Raebiger nets, shortly LR-nets. In this thesis
we treat two problems on asymptotic behavior of these operator nets.
First problem is to generalize well known theorems for Ces`aro averages of a single operator to LR-nets, namely to generalize the Eberlein and Sine theorems. The second problem is related
to the strong convergence of Markov LR-nets on L1-spaces. We prove that the existence of a lower-bound functions is necessary and sufficient for asymptotic stability of LR-nets of
Markov operators.
9
Hesseborn, Alexander, und Mårten Vuorinen. „Correctness Attraction Analysis in C“. Thesis, KTH, Skolan för teknikvetenskap (SCI), 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-233209.
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Is the execution of computer programs really deterministic? Will a perturbation cause the program to break or give an incorrect output?In this project, the goal is to add perturbations to programs in C, and see if we can get the same result as the program executed without said perturbations.The algorithm takes source code and transforms it into XML. The code is transformed in order to identify nodes to perturb. When the nodes are identified we add a perturbation to some node and transform the XML code back to source code. When we have the perturbed code we execute the code and compare it to the code executed without any perturbations.We have, using cPerturb, tested several nodes in five differ- ent programs and identified a subset of these which yields the same result as the unperturbed programs.Måste en körning av ett program gå till på samma sätt för att få samma resultat? En introducerad störning kommer påverka hur koden körs, men behöver det påverka resultatet? Vårt mål med det här projektet var att skapa mjukvara i C som medvetet stör program, och jämföra det med ett program som körts utan störningar. Algoritmen vi tagit fram transformerar källkoden till XML. Därefter identifierar den noder som går att störa, lägger till en störning och transformerar XML-koden tillbaka till käll-kod. Därefter körs den störda koden och jämförs med koden som körts utan störning. Vi har, med hjälp av cPerturb, testat ett flertal noder över fem olika program och därmed identifierat noder som ger samma resultat som den ickestörda koden.
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Eckstein, Bernd. „Bandcounter: Counting bands of multiband chaotic attractors“. Stuttgart : Universitätsbibliothek der Universität Stuttgart, 2006. http://nbn-resolving.de/urn:nbn:de:bsz:93-opus-28244.
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Cyr, Ciara Yvonne. „Attraction Process Among Identified Sport Fans“. TopSCHOLAR®, 2014. http://digitalcommons.wku.edu/theses/1436.
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Since automatic attention is given to beauty, and appearance is the first thing noticed upon meeting a person, one would assume attractiveness is the more important selection factor for a relationship partner. Theories such as the matching hypothesis and mortality salience dispute this idea. The matching hypothesis proposes selection occurs between individuals similar in attractiveness, not necessarily selecting the most attractive individual available. Mortality salience suggests attractiveness is used in selecting a partner for short-term relationships, but discounts physical attractiveness for long-term relationships. This theory proposes an ideal partner for a long-term relationship is selected based on similarity of beliefs. Mortality salience is centered on beliefs of religious groups, with which individuals can become highly identified. Individuals can also become highly identified with a sport team. This connection can be even stronger than the connection with a religious group. Since this connection is so strong, and identification with a religious group can influence selecting a partner, identification with a sport team might have a similar influence. This study attempts to bridge the gap from attraction and dating to sport fan identification. The first hypothesis is sport fans highly identified with the University of Kentucky men’s basketball team will rate a model fan for that team as more attractive than a model fan from a rival team. The second hypothesis is those fans will rate the model fan for the University of Kentucky’s basketball team as more attractive when prompted with a long-term relationship condition as opposed to a short term condition. Participants in this study completed demographics before being randomly assigned an opposite sex dating profile page. They were informed the website they were evaluating was either for people looking for long-term or short-term relationships. They completed a questionnaire about their opinion of the person in the profile, and the Sport Spectator Identification Scale for both the University of Kentucky and the University of Louisville men’s basketball teams. The hypotheses and previous research were not supported. This study did produce other interesting findings. The additional findings lend some support to the sociometer theory proposing self-esteem as an important relationship factor.
12
Martínez-García, Marina. „Statistical analysis of neural correlates in decision-making“. Doctoral thesis, Universitat Pompeu Fabra, 2014. http://hdl.handle.net/10803/283111.
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We investigated the neuronal processes which occur during a decision-
making task based on a perceptual classi cation judgment.
For this purpose we have analysed three di erent experimental paradigms
(somatosensory, visual, and auditory) in two di erent species (monkey and
rat), with the common goal of shedding light into the information carried by
neurons.
In particular, we focused on how the information content is preserved in
the underlying neuronal activity over time. Furthermore we considered how
the decision, the stimuli, and the con dence are encoded in memory and,
when the experimental paradigm allowed it, how the attention modulates
these features. Finally, we went one step further, and we investigated the
interactions between brain areas that arise during the process of decision-
making.Durant aquesta tesi hem investigat els processos neuronals que es pro- dueixen durant tasques de presa de decisions, tasques basades en un ju- dici l ogic de classi caci o perceptual. Per a aquest prop osit hem analitzat tres paradigmes experimentals diferents (somatosensorial, visual i auditiu) en dues espcies diferents (micos i rates), amb l'objectiu d'il.lustrar com les neurones codi quen informaci on referents a les t asques. En particular, ens hem centrat en com certes informacions estan cod- i cades en l'activitat neuronal al llarg del temps. Concretament, com la informaci o sobre: la decisi o comportamental, els factors externs, i la con- ana en la resposta, b e codi cada en la mem oria. A m es a m es, quan el paradigma experimental ens ho va permetre, com l'atenci o modula aquests aspectes. Finalment, hem anat un pas m es enll a, i hem analitzat la comu- nicaci o entre les diferents arees corticals, mentre els subjectes resolien una tasca de presa de decisions.
13
Durantay, Lionel. „Analyse vibratoire d'un stator de machine électrique asynchrone et modélisation des forces d'attraction électromagnétique d'entrefer“. Vandoeuvre-les-Nancy, INPL, 1994. http://www.theses.fr/1994INPL103N.
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Ce mémoire présente deux contributions à l'analyse vibratoire des machines électriques asynchrones de moyenne puissance. Dans la première partie, nous proposons une simulation 2D des principaux défauts géométriques de l'entrefer et la détermination des résultantes de forces électromagnétiques associées. Un mailleur dédié a été développé intégrant les paramètres de trajectoire rotorique et de défauts géométriques des contours de l'entrefer. Les forces d'attraction magnétique obtenues par méthodes analytiques et numériques sont comparées et validées. Nous réalisons la simulation électromécanique d'un excentrement dynamique du rotor caractérisé par des forces de modulation à très basse fréquences. Ceci est rendu possible par la rapidité de calcul du potentiel vecteur magnétique par l'approximation du premier harmonique. La seconde partie est consacrée à l'étude vibratoire expérimentale d'un stator bobine, imprégné, monté dans sa carcasse, et au calcul des fréquences propres associées. Les modules d'Young des différents matériaux composites et viscoélastiques composant le bobinage sont déterminés à l'aide d'un viscoanalyseur. Les caractéristiques mécaniques des encoches sont estimées par une méthode d'homogénéisation. Les fréquences propres, déformées modales et amortissements sont identifiés par une analyse expérimentale au marteau de choc et au pot vibrant. Le calcul des fréquences propres par modèle dynamique 2D-EF utilise une loi de comportement en déformation plane et un recalage fréquentiel par une méthode d'optimisation de type gradient
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Fälton, Emelie. „The Social Construction of Swedish Nature as a Touristic Attraction“. Thesis, Linköpings universitet, Tema Miljöförändring, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-130538.
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Sweden is a country with a lot of tourism that is dependent on nature as a touristic resource. Nature itself is a complex concept with different interpretations. In this thesis, the social construction of the Swedish nature as a touristic attraction is scrutinized. A total of 671 visual images with belonging descriptive texts has been collected from an online image bank where information about Sweden is available for foreign marketers. The material was analysed in order to answer questions about how the Swedish nature and the touristic approach to it are presented, how nature features are assigned to it and how the relationship between nature and humans is presented. The composition and portraiture of the images and prominent themes and patterns in the textual descriptions have been identified as well. The theoretical framework is based on discourse theory, while the methodological framework is based on inspiration from both discourse analysis and content analysis. The result revealed that Swedish nature is presented as part of the rural Sweden with mountains, forests and littoral areas as the main elements. Swedish nature is foremost portrayed as wild and authentic, but also as sublime and pristine to a lesser extent. It is also portrayed as a place for touristic activities with a focus on the outdoors and physical activity. The relation between nature and humans differ, but the Swedish people are portrayed as more connected to nature than tourists
15
Farmer, George David. „A computational and behavioural analysis of rationality in contextual preference reversals“. Thesis, University of Manchester, 2015. https://www.research.manchester.ac.uk/portal/en/theses/a-computational-and-behavioural-analysis-of-rationality-in-contextual-preference-reversals(cb751b6b-4f09-4a5c-a674-90398a9e30bc).html.
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The attraction effect reveals that people do not compare alternatives independently of one another. Instead, they make comparisons, such that preferences between two alternatives can be reversed by adding or removing otherwise irrelevant alternatives. This behaviour is particularly difficult for rational models of decision making to explain since such models require the independent evaluation of alternatives. As such these models describe preference reversal behaviour as irrational. This thesis examines what rational decision making should look like once a person's cognitive bounds have been taken into account. The key finding is that contextual preference reversals like the attraction effect, far from being irrational, actually result from people making better decisions than they would if they assessed alternatives independently of one another. The research was grouped into three objectives concerning the attraction effect and the rationality of human cognition. The first of these was to identify under what conditions people exhibit the attraction effect, and what consequences the behaviour has for the outcomes they experience. Two experiments revealed that the effect is only exhibited in choice sets where alternatives are approximately equal in value and therefore hard to tell apart. This finding also means that the potential negative consequences of exhibiting the attraction effect are very small, because it only occurs when alternatives are similar in value. The second objective was to develop a computationally rational model of the attraction effect. Computational rationality is an approach that identifies what the optimal behaviour is given the constraints imposed by cognition, and the environment. Our model reveals why people exhibit the attraction effect. With the assumption that people cannot calculate expected value perfectly accurately, the model shows that in choices between prospects, the attraction effect actually results in decisions with a higher expected value. This is because noisy expected value estimates can be improved by taking into account the contextual information provided by the other alternatives in a choice set. The final objective was to provide evidence for our model, and the computational rationality approach, by making a novel prediction. We conducted an experiment to test the model's prediction that the attraction effect should be much reduced in the loss domain. We replicated existing attraction effect studies and extended them to the loss domain. The results replicated previous results in the gain domain and simultaneously revealed the novel finding that people did not exhibit the effect in the loss domain. People exhibit the attraction effect as a result of making the best decision possible given the cognitive resources they have. Understanding decision making as computationally rational can provide deep insights into existing phenomena. The method allows us to ascertain the causal link between cognitive mechanisms, a person's goal, and their decision making.
16
Goldspink, Christopher. „Social attractors : an examination of the applicability of complexity theory to social and organisational analysis /“. Richmond, N.S.W. : University of Western Sydney, Hawkesbury, 1999. http://library.uws.edu.au/adt-NUWS/public/adt-NUWS20030812.094325/index.html.
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Formica, Sandro. „Destination Attractiveness As A Function Of Supply And Demand Interaction“. Diss., Virginia Tech, 2000. http://hdl.handle.net/10919/11273.
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The driving force of the tourism industry is represented by the attractions at destination. Travelers have no reason to visit destinations that have nothing to offer. Tourism research has demonstrated that attraction studies are necessary in the understanding of the elements that encourage people to travel. Achieving the goal of measuring destination attractiveness requires the understanding of its components and their relationships. There are two ways of examining attractiveness: by studying the attractions or by exploring the attractiveness perceptions of those who are attracted by them. As competition among tourism destinations increases and tourist funding decreases, it is of vital importance to understand how the inventory of existing attractions at destination relates to the perceptions that travelers have of those attractions.
Tourism literature provides only a limited number of studies addressing destination attractiveness. Those studies focus exclusively on the measurement aspect of attractiveness and ignore the analysis of its components. The purpose of this study was to generate a new measurement tool for destination attractiveness and to examine the relationship between its elements. The principles of regional analysis, tourism planning, and tourism attraction research provided the foundation for a measurement and hypothesis testing model. This model is based on the assumption that tourism is a system, which is a function of supply and demand interaction.
Four attraction dimensions - tourism services and facilities, cultural/historical, rural lodging, and outdoor recreation - were found to represent the attractiveness portfolio of the destination. According to the findings, no correlations were found between demand and supply importance of the four dimensions. Among demand representatives, market segments perceive and value attractions in different ways. The study explored the attractiveness evaluation of eight tourist regions and discovered correlations between demand and supply indicators. Additionally, it was established that the overall regional measures of demand and supply destination attractiveness explain the economic benefits of tourism in the same region.
Among the contributions of this study is the development of a model that allows the simultaneous empirical assessment of demand and supply indicators of destination attractiveness. The findings of this study provided important implications for the development of robust tourism plans, promotional strategies, and resource allocation policies.Ph. D.
18
Bowman, William John II. „Misattribution of Interpersonal Attraction: A Case of Mistaken Chemistry or Cognition“. TopSCHOLAR®, 1988. https://digitalcommons.wku.edu/theses/2068.
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Prior research endorsed two theories of misattribution of interpersonal attraction. Both the two-component theory and the excitation transfer theory demonstrate misattribution and, in combination, enhance the probability of misattribution. However, which theory provides the primary source of misattribution has not been distinguished. The present study asked 60 undergraduate males to rate their interpersonal attraction toward a female in a video recording engaging in self disclosure. A manipulation of different levels of environmental saliency and physiological arousal was used to determine which condition or combination of conditions is most likely to elicit misattribution of interpersonal attraction. An analysis of variance followed by an analysis of covariance was performed on the interpersonal attraction ratings. The covariate of base pulse rate was used to control for individual difference of arousal. The results did not indicate a statistical difference of misattribution under any of the manipulated conditions. The expansion of the arousal conditions is discussed as a prerequisite of misattribution effects. Further research is recommended in the areas of female misattribution of interpersonal attraction and individual cognitive recovery levels.
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Butler, Christopher L. „UNDERSTANDING THE PERCUSSION WORKS OF ALEJANDRO VIÑAO: AN ANALYSIS AND PERFORMER’S GUIDE OF WATER FOR PERCUSSION ENSEMBLE“. UKnowledge, 2016. http://uknowledge.uky.edu/music_etds/58.
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The music of Alejandro Viñao is driven primarily by rhythm rather than traditional classical music components such as melody, harmony, and formal structures. As such, this focus on rhythm showcases the innovation of multiple time, defined as the musical simulation of various meters and tempi. Pioneered by Conlon Nancarrow, this rhythmic innovation is identified within Water (2013).
The purpose of this dissertation is to provide insight and analysis of the specific musical characteristics of Viñao’s compositional style. These characteristics include the use of rhythmic grooves, attractors, echo effect, tenuto markings, Euclidean rhythms, and water imagery. Once this analysis has been completed, this dissertation then highlights the necessary practicalities of performance by discussing aspects such as conducting, rehearsal preparation, setup configuration, mallet considerations, and the technical aspects of performing bongos and congas.
20
Smith, Hunter Jewel Marianna. „A multidimensional analysis of physical attractiveness in the formation of first impressions“. PDXScholar, 1986. https://pdxscholar.library.pdx.edu/open_access_etds/3634.
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Before any words are spoken, an individual's appearance is his or her first line of nonverbal communication with the rest of the world. Prior research conducted on physical attractiveness has been vague and contradictory and has not assessed its many components. Rather, past investigators have perceived physical attractiveness as a "unidimensional" concept.
Several phases were involved in the task of proving or disproving the hypotheses of the study. The first general phase began with the selection of photographic subjects, progressed into the creation of a set of photographs which were to become the stimuli, and proceeded to the selection of the photo judges, whose evaluations would determine the final select group of 18 photographs and their physical attractiveness intensity levels.
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McMichen, James. „Determination of areas and basins of attraction in planar dynamical systems using meshless collocation“. Thesis, University of Sussex, 2016. http://sro.sussex.ac.uk/id/eprint/65707/.
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This work is focused on the approximation of sets of attractive solutions of planar dynamical systems. Existing work has shown that for many dynamical systems a Riemannian contraction metric can be used to determine sets of solutions with certain attraction properties. For autonomous dynamical systems in R² it has been shown that the Riemannian contraction metric can be reduced to a scalar weight function W. In this work we show that a similar result holds true for finite-time dynamical systems with one spatial dimension. We show how meshless collocation can be used to construct an approximation of W. The approximated weight function can then be used to determine subsets of the area of exponential attraction. This is the first time a method has been introduced to approximate finite-time areas of exponential attraction. We also give a convergence proof for the method. For autonomous dynamical systems in R² there already exists a method that uses W to determine a subset of the basin of attraction of an exponentially stable periodic orbit, Ω. However that method relies on properties of Ω being known. We show that the existing equation for W can be manipulated so that no knowledge of the periodic orbit is required to approximate W. We present a method that utilises meshless collocation to approximate W and show that the method is convergent. The approximant of W is then used to determine subsets of the basin of attraction of Ω.
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Julitz, David. „Numerical analysis of random dynamical systems in the context of ship stability“. Universitätsbibliothek Chemnitz, 2004. http://nbn-resolving.de/urn:nbn:de:swb:ch1-200401234.
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We introduce numerical methods for the analysis of random dynamical systems.
The subdivision and the continuation algorithm are powerful tools which will be
demonstrated for a system from ship dynamics. With our software package we are
able to show that the well known safe basin is a moving fractal set. We will also
give a numerical approximation of the attracting invariant set (which contains a
local attractor) and its evolution.
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Tolliver, Staci. „Hurting the Ones They Love: Character Analysis and Original Screenplay Crimes of Passion“. ScholarWorks@UNO, 2012. http://scholarworks.uno.edu/honors_theses/22.
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The thesis is a ten-page analysis on two films, Fatal Attraction and Lakeview Terrace. The thesis begins with a brief introduction to the horror genre and its subgenre in which the two films and original screenplay are categorized, psychological horror. It covers all the important elements of a film and screenplay: conflict, arc, goal, structure and plot. The thesis also consists of feminists’ reactions to Fatal Attraction, and examines whether the original 60- page screenplay helps or worsens the image of women. The screenplay also raises the question if having the villains need to be insane to prove a point. Further in the thesis is a description of the original screenplay Crimes of Passion and its main characters Jennifer, Alex and Keith. Jennifer, the heroine, becomes the target of scorned lover and police officer Keith. Alex, Keith’s rival, must protect Jennifer. The analysis ends with the restated questions the audience must have in mind and answer while reading the screenplay.
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Insabato, Andrea. „Neurodynamical theory of decision confidence“. Doctoral thesis, Universitat Pompeu Fabra, 2014. http://hdl.handle.net/10803/129463.
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Decision confidence offers a window on introspection and onto the evaluation mechanisms associated
with decision-making. Nonetheless we do not have yet a thorough understanding of its neurophysiological and computational substrate.
There are mainly two experimental paradigms to measure decision confidence in animals: post-decision wagering and uncertain option.
In this thesis we explore and try to shed light on the computational mechanisms underlying confidence based decision-making in both experimental paradigms.
We propose that a double-layer attractor neural network can account for neural recordings and behavior of rats in a post-decision wagering experiment. In this model a decision-making layer takes the perceptual decision and a separate confidence layer monitors the activity of the decision-making layer and makes a judgment about the confidence in the decision.
Moreover we test the prediction of the model by analyizing neuronal data from monkeys performing a
decision-making task. We show the existence of neurons in ventral Premotor cortex that encode decision confidence. We also found that both a continuous and discrete encoding of decision confidence are
present in the primate brain. In particular we show that different neurons encode confidence through three different mechanisms: 1. Switch time coding, 2. rate coding and 3. binary coding.
Furthermore we propose a multiple-choice attractor network model in order to account for uncertain option tasks. In this model the confidence emerges from the stochastic dynamics of decision neurons, thus making a separate monitoring network (like in the model of the post-decision wagering task) unnecessary. The model explains the behavioral and neural data recorded in monkeys lateral intraparietal area as a result of the multistable dynamics of the attractor network, whereby it is possible to make several testable predictions.
The rich neurophysiological representation and computational mechanisms of decision confidence evidence the basis of different functional aspects of confidence in the making of a decision.El estudio de la confianza en la decisión ofrece una perspectiva ventajosa sobre los procesos de introspección y sobre los procesos de evaluación de la toma de decisiones. No obstante todav'ia no tenemos un conocimiento exhaustivo del sustrato neurofisiológico y computacional de la confianza en la decisión. Existen principalmente dos paradigmas experimentales para medir la confianza en la decisión en los sujetos no humanos: apuesta post-decisional (post-decision wagering) y opción insegura (uncertain option). En esta tesis tratamos de aclarar los mecanísmos computacionales que subyacen a los procesos de toma de decisiones y juicios de confianza en ambos paradigmas experimentales. El modelo que proponemos para explicar los experimentos de apuesta post-decisional es una red neuronal de atractores de dos capas. En este modelo la primera capa se encarga de la toma de decisiones, mientras la segunda capa vigila la actividad de la primera capa y toma un juicio sobre la confianza en la decisión. Sucesivamente testeamos la predicción de este modelo analizando la actividad de neuronas registrada en el cerebro de dos monos, mientras estos desempeñaban una tarea de toma de decisiones. Con este análisis mostramos la existencia de neuronas en la corteza premotora ventral que codifican la confianza en la decisión. Nuestros resultados muestran también que en el cerebro de los primates existen tanto neuronas que codifican confianza como neuronas que la codifican de forma continua. Más en específico mostramos que existen tres mecanismos de codificación: 1. codificación por tiempo de cambio, 2. codificación por tasa de disparo, 3. codificación binaria. En relación a las tareas de opción insegura proponemos un modelo de red de atractores para opciones multiplas. En este modelo la confianza emerge de la dinámica estocástica de las neuronas de decisión, volviéndose así innecesaria la supervisión del proceso de toma de decisiones por parte de otra red (como en el modelo de la tarea de apuesta post-decisional). El modelo explica los datos de comportamiento de los monos y los registros de la actividad de neuronas del área lateral intraparietal como efectos de la dinámica multiestable de la red de atractores. Además el modelo produce interesantes y novedosas predicciones que se podrán testear en experimentos futuros. La compleja representación neurofisiológica y los distintos mecanísmos computacionales que emergen de este trabajo sugieren distintos aspectos funcionales de la confianza en la toma de decisiones.
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Starks, Tyrel J. „Psychometric analysis of the Attraction/Intimacy Assessment Inventory : outlining the construct of sexual orientation and assessing its components /“. Available to subscribers only, 2009. http://proquest.umi.com/pqdweb?did=1895040751&sid=1&Fmt=2&clientId=1509&RQT=309&VName=PQD.
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Thesis (Ph. D.)--Southern Illinois University Carbondale, 2009."Department of Psychology." Keywords: Sexual orientation, Sexual behavior, Sexual attraction, Sexual identity, Gay, Lesbian, Bisexual, Bisexual mental health, Assessment, Attraction/Intimacy Assessment Inventory Includes bibliographical references (p.148-157). Also available online.
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Battin, Justin M. „Attracted to the Medium: An Analysis of Social Behaviors, Advertising, and Youth Culture in the Emerging Mobile Era“. Thesis, University of North Texas, 2011. https://digital.library.unt.edu/ark:/67531/metadc84172/.
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This thesis is a reception study that examines potential reasons why the adolescent to college aged demographic of youth culture is embracing communicative and informational mobility. The project attests that the move to mobility is motivated by two major factors, the attraction of being an early adopter of technology and the way social behaviors are made attractive in mobile marketing. Chapter 1 explores the importance of these social behaviors, as they are very much intertwined and contribute to how youth acclimate into society. Chapter 2 demonstrates that creating social distinction and cultural capital is linked to being an early adopter of technology. The remaining portion of the document examines recent mobile advertisements and why youth would be attracted to the aesthetic and thematic elements contained in the advertisements. Chapter 3 examines how Blackberry utilizes the behavior of creating and expressing identity in their advertisements. Chapter 4 focuses on how Apple has worked to create a community centered around their brand. Finally, Chapter 5 looks at how Google/Android has highlighted the acquisition, sharing, and utilization of content through the phenomenon of applications. With this project, I hope to illustrate the rationale why youth would be attracted to communicative and informational mobility.
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OLIVEIRA, JOSANE GOMES WEBER. „FACTORS OF ATTRACTION AND MAINTENANCE OF SOFTWARE FIRMS IN JUIZ DE FORA: AN ANALYSIS FROM THE PERSPECTIVE OF SUSTAINABLE REGIONAL DEVELOPMENT“. PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2005. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=6660@1.
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A partir de meados do século XX, os avanços científicos e
tecnológicos
desencadearam uma onda de transformações que vem atingindo
as sociedades em
seus aspectos: cultural, social, político, comportamental e
econômico. Neste
contexto, empresas intensivas em conhecimento ou de base
tecnológica, como as
do setor de software, vêm ganhando espaço no cenário
econômico e galgando
importantes posições nos mercados. Há um resgate da
dimensão local na atividade
produtiva e a discussão sobre temas como desenvolvimento
regional sustentável,
Arranjos Produtivos Locais - APLs e PLOLHX de inovação tem
sido cada vez mais
constante. O presente trabalho buscou analisar, sob o ponto
de vista dos atores
locais, os fatores de atração e fixação de empresas de
software na região do
município de Juiz de Fora, Zona da Mata de Minas Gerais.
Para tanto, foram
levantados alguns dados e realizadas entrevistas com
diferentes atores, cuja
análise permitiu entender melhor as possibilidades e
dificuldades da região em
relação ao processo de atração e manutenção das empresas
deste setor e sugerir
caminhos, que possam levar a forma mais adequada para
realização dos dois
processos supracitados. Este estudo pretende fornecer
subsídios para futuras
políticas de atração de investimentos para a região e para
a busca de alternativas
de desenvolvimento regional sustentado.From the late 20th century on all the scientific and technological advances occurred have brought a wave of changing`s on several aspects of our society such as cultural, political, behaviorism and economical which have made intensive knowledge enterprises or those based in technologies like software production ones to win more space in the economic scenario and reach important positions in the markets. There has been a rescue of the local dimension in the productive activities and the discussions around subjects as sustainable developing in particular regions, Local Productive Arrangements - APL, new ways of innovation, among others, have been getting more importance each day. This work has the intention of analyzing the factors of attraction and establishment of software enterprises in the Juiz de Fora, Minas Gerais surroundings, under the local actors` point of view. Therefore some data were obtained from interviews with different actors and their analysis is going to make it better to understand both the possibilities and difficulties in the processes of attracting and maintaining these kind of enterprises in the considered region and it`s going to suggest actions to bring the most suitable ways to make sure the two of the processes already mentioned happen. This study is also going to present sources for future investment policies to the region and alternatives for sustainable developing.
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Ruben, Jennifer Lynn. „Illusionary Strength; An Analysis of Female Empowerment in Science Fiction and Horror Films in Fatal Attraction, Aliens, and The Stepford Wives“. Wright State University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=wright1355753729.
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Nogueira, Fernando Antonio Nunes. „The policy to attract industrial investments of CearÃ, and the impact on jobs: an analysis of period 2002 - 2005“. Universidade Federal do CearÃ, 2008. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=2705.
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nÃo hÃThis study aims to empirically assess the effectiveness of the Fund for Industrial Development (FDI) in the generation of employment, including the period from 2002 to 2005. Through the database of information from companies that received tax incentives to install, upgrade or relocate their investments in the State, were estimated two models: the first uses information cross-section and aims to raise the rate of employment growth formal. The other, using panel data, to investigate the effect of GDP per capita, the stock of human capital and consumption of electric power on the stock of formal jobs With regard to results, we can infer that the FDI was ineffective on its goal of generating jobs, is seen that the impact on the stock or the rate of formal job growth was zero, so future policies for industrial development the state of Cearà can be corrected (or revised) on how to
O presente trabalho objetiva avaliar empiricamente a eficÃcia do Fundo de Desenvolvimento Industrial â FDI na geraÃÃo de emprego, compreendendo o perÃodo 2002 a 2005. AtravÃs da base de dados com informaÃÃes das empresas que receberam incentivo fiscal para se instalar, modernizar ou realocar seus investimentos no estado, foram estimados dois modelos: o primeiro utiliza informaÃÃes âcross-sectionâ e tem por finalidade captar a taxa de crescimento do emprego formal. O outro, utiliza dados em painel, para averiguar o efeito do PIB per capita, do estoque de capital humano e do consumo de energia elÃtrica sobre o estoque de empregos formais. No tocante aos resultados, pode-se inferir que o FDI foi ineficaz quanto à sua meta de gerar empregos, haja vista que o impacto no estoque e na taxa de crescimento de postos de trabalhos formais foi nulo; desta forma, futuras polÃticas de desenvolvimento industrial do estado do Cearà poderÃo ser corrigidas (ou revistas) quanto à forma de implementaÃÃo.
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Quest, A. Del. „Out of the Way and Out of Place: An Interpretative Phenomenological Analysis of the Experiences of Social Interactions of Bisexually Attracted Young People“. PDXScholar, 2014. https://pdxscholar.library.pdx.edu/open_access_etds/2002.
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Research addressing the concerns of bisexually attracted youth has markedly increased in the past few years, yet remains limited in comparison to that addressing the issues of lesbian and gay youth (Brewster & Moradi, 2010). Those few studies treating bisexual participants as distinct from lesbian and gay participants have findings indicating that some youth who identify as bisexual experience higher rates of depression, pregnancy, substance abuse, suicidal ideations, and suicide attempts compared to their lesbian and gay peers (Kennedy & Fisher, 2010; Lewis, Derlega, Brown, Rose, & Henson, 2009; Saewyc, Homma, Skay, Bearinger, Resnick, & Reis, 2009). Most commonly, however, research studies examine all lesbian, gay, bisexual, transgender, and queer participants as one group, and little is known about the ways in which these distinct groups differ. Biphobia, defined as the aversion felt toward bisexuality and bisexuals as a social group or as individuals, contributes to barriers in addressing this gap.
The primary objective of this study was to gain an understanding of how the participants recalled their social interactions and how they made sense of them. In depth, semi-structured interviews were conducted with ten young people who were bisexually attracted when they were of high school age. Results were analyzed and discussed using an Interpretative Phenomenological Analysis (IPA) approach. Analyses of these accounts revealed the ways these young people made sense of feeling dismissed, isolated, invisible, and unsafe in their environments and the ways they used their observations to control future interactions. The participants discussed their experiences with coming out to family members and friends and the strain of choosing to hide their attractions to more than one gender.
These findings indicate the need for services offering specific supports and interventions for bisexually attracted youth. Social workers, youth workers, and educators can best serve this population by acknowledging the uniqueness of their experiences. Future research, focused on group specific concerns, could close the existing gap in the knowledge base.
31
Chen, Jing. „SOLUTION AND SOLID STATE INTERACTIONS BETWEEN IONIC π-SYSTEMS“. UKnowledge, 2006. http://uknowledge.uky.edu/gradschool_diss/289.
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Although attractive interactions between π systems (π-π interaction) have been known for many years, understanding of its origin is still incomplete. Quantitative measuring of π-stacking is challenging due to the weak nature of the π-π interaction. This dissertation aims at elucidating a quantitative conformational analysis by NMR ring current anisotropy of an organic compound capable of intramolecular π-stacking in solution and studying charge effects on the stacking of π-systems. This dissertation offers four contributions to the area. (1) A general approach to four-state, conformational analysis based on the magnetic anisotropy of molecules undergoing fast dynamic exchange is described. (2) Study unveiled the importance of charges in the conformation of a dication in the solution. (3) Novel aromatic salt pairs of triangulene derivatives with the delocalized cation-anion interaction were synthesized and studied. (4) Study unveiled ionic π-systems preferred face-to-face stacking due to strong cation-π and anion-cation attractions.
A general protocol for the application of magnetic anisotropy to quantitative multi-state conformational analysis of molecules undergoing fast conformational exchange was suggested in the current study. The reliability of this method of conformational analysis was checked by the mass balance. VT-NMR was also conducted to study the enthalpic parameters. This technique can be further used to study canonical interactions such as ion pairing, hydrogen boning, and molecular recognition.
In the current study, dependence of the probe conformations on the dispersive interactions at the aromatic edges between solvent and probes was tested by conformational distributions of the fluorinated derivatives (2b and 2c) of the probe molecule (1a). Solution and solid studies of these molecules put the previous conclusion drawn by the Cammers group in question. Current studies show that the dispersive interaction at the aromatic edge could not be the predominant force on the conformational changes in the probe molecule 1a during the fluoroalkanol perturbation. This study indicated that charges might be important in the formation of the folding conformations in the solution and solid state of 1a, 2b, and 2c. A contribution of this thesis was to prepare and study a conformational model that lacked charges. The previous molecules were charged.
The solid-state structures of pyridinium-derived aromatic rings from the CSD (Cambridge Structural Database) were studied to investigate the π-π interaction between cationic π-systems in solid state. Novel aromatic salt pairs of triangulene derivatives with the delocalized cation-anion interaction were synthesized to study the π-π interaction between two aromatic rings that carried opposite charges. This study showed that the interaction between ionic π-systems can be enhanced by cation-π and anion-cation attractions. The stackings of these π-systems introduce more overlap, closer packing and stronger atomic contact than that of the solid states of comparable neutral species. Cation-π and anion-cation attractions are synergistic in aromatic salts.
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Khawaja, Masud S. „The Mediating Role of Positive and Negative Emotional Attractors between Psychosocial Correlates of Doctor-Patient Relationship and Treatment Adherence in Type 2 Diabetes“. Case Western Reserve University School of Graduate Studies / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=case1283995516.
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33
Scoppa, Martin Dennis. „Towards a theory of distributed attraction: the effects of street network configuration upon the distribution of retail in the city of Buenos Aires“. Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/47568.
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This dissertation tests the proposition that the spatial structure of street networks affects the distribution of urban land use. Specifically, it examines patterns of commercial land use utilizing parcel based data on retail and service businesses location. While previous studies report a correlation between spatial structure and patterns of commercial land use, these studies do not typically control for the effect of key variables likely to contribute to the spatial distribution of retail and service establishments. In order to redress this balance, and using the City of Buenos Aires as a case study, this dissertation studies the correlation between commercial land use frontage and street connectivity measures, while controlling for street widths, density of population and employment, interstore externalities, zoning regulations, and distance to transit stations. Buenos Aires is chosen for its regular plan radiating from a well-defined CBD, a plan which would be expected to conform to standard urban attraction models of retail location. Results of multiple regression models indicate that, after controlling for these variables, measures of street connectivity account for key aspects of the distribution of retail, including linear distributions along major radial and peripheral streets at a distance from the CBD. Thus, the dissertation supports the thesis that "urban attraction" should not be conceptualized in terms of distances from a unique central location, or a number of central locations, but rather in terms of a model of distributed centrality governed by the structure of street networks.
34
Rana, Tejsingh. „Enhancement of Predictive Capability of Transit Boardings Estimation and Simulation Tool (TBEST) Using Parcel Data: An Exploratory Analysis“. Scholar Commons, 2010. http://scholarcommons.usf.edu/etd/3468.
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TBEST is a comprehensive third generation transit demand forecasting model, developed by the FDOT Public Transit Office (PTO) to help transit agencies in completing their Transit Development Plans (TDPs). The on-going project funded by FDOT, related to TBEST, aims at further enhancing the capabilities of the TBEST model based on additional opportunities identified by the research team. The project focuses on enhancing TBEST’s capabilities in following areas: 1) Improving the precision of socio- demographic data by using property appraisal data (parcel data) and, 2) Improving the quality of data regarding trip attraction. Based on the improvement areas, this study aims at performing an exploratory analysis to 1) Identify the differences in activity levels (population and employment) within transit stop buffers due to change in input data i.e. from aggregate census data to disaggregate parcel data. 2) Explore various strategies (development of employment based trip attraction and, parcel land use based trip attraction and exploring how special generators are dealt with in the past studies) to enhance the trip attraction capability of the TBEST model. The results obtained from this analysis provide insights on the strategies and helps define suggestions to further enhance the precision of TBEST model. The results show that use of parcel level data improves the accuracy in capturing the activity levels within the catchment area of each stop. The results also suggest use of parcel land use based trip attraction for stops with special generators or use of interaction variable (interaction between special generator dummy and size (square footage etc.) of the special generator) to enhance the trip attraction capability of the TBEST model.
35
Hendon, Adrienne Leigh. „Pick-Up lines: To Use a Neg or a Flippant?“ Digital Commons @ East Tennessee State University, 2012. https://dc.etsu.edu/etd/1446.
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Pick-up lines are a "ritual that tries to turn strangers into lovers" (Murray, 1985, p.17). By studying how pick-up lines are perceived by the population, we might learn how the phenomenon of short- or long-term mating is initiated. By taking into account mating strategies, mate value, attractiveness, and flirting strategies, a pattern of behaviors and reactions may be observed. This study examines perceived pick-up line appropriateness and effectiveness when the attractiveness of the man delivering them varies. To test the effectiveness of 2 different types of pick-up lines, an online survey featuring 1 of 4 videos was administered. Results indicated that a humorous pick-up line was perceived as more effective and favorable than a slightly insulting one. An attractive man was perceived to be more communicatively competent than an unattractive man. Men, regardless of attractiveness, were perceived as more socially attractive when using a humorous pick-up line.
36
Raman, Dhruva Venkita. „On the identifiability of highly parameterised models of physical processes“. Thesis, University of Oxford, 2016. https://ora.ox.ac.uk/objects/uuid:f58aa335-db0a-495b-8eef-1ddb363cbd19.
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This thesis is concerned with drawing out high-level insight from otherwise complex mathematical models of physical processes. This is achieved through detailed analysis of model behaviour as constituent parameters are varied. A particular focus is the well-posedness of parameter estimation from noisy data, and its relationship to the parametric sensitivity properties of the model. Other topics investigated include the verification of model performance properties over large ranges of parameters, and the simplification of models based upon their response to parameter perturbation. Several methodologies are proposed, which account for various model classes. However, shared features of the models considered include nonlinearity, parameters with considerable scope for variability, and experimental data corrupted by significant measurement uncertainty. We begin by considering models described by systems of nonlinear ordinary differen- tial equations with parameter dependence. Model output, in this case, can only be obtained by numerical integration of the relevant equations. Therefore, assessment of model behaviour over tracts of parameter space is usually carried out by repeated model simulation over a grid of parameter values. We instead reformulate this as- sessment as an algebraic problem, using polynomial programming techniques. The result is an algorithm that produces parameter-dependent algebraic functions that are guaranteed to bound user-defined aspects of model behaviour over parameter space. We then consider more general classes of parameter-dependent model. A theoretical framework is constructed through which we can explore the duality between model sensitivity to non-local parameter perturbations, and the well-posedness of parameter estimation from significantly noisy data. This results in an algorithm that can uncover functional relations on parameter space over which model output is insensitive and parameters cannot be estimated. The methodology used derives from techniques of nonlinear optimal control. We use this algorithm to simplify benchmark models from the systems biology literature. Specifically, we uncover features such as fast-timescale subsystems and redundant model interactions, together with the sets of parameter values over which the features are valid. We finally consider parameter estimation in models that are acknowledged to im- perfectly describe the modelled process. We show that this invalidates standard statistical theory associated with uncertainty quantification of parameter estimates. Alternative theory that accounts for this situation is then developed, resulting in a computationally tractable approximation of the covariance of a parameter estimate with respect to noise-induced fluctuation of experimental data.
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Pitarch, Pérez José Luis. „Contributions to fuzzy polynomial techniques for stability analysis and control“. Doctoral thesis, Universitat Politècnica de València, 2014. http://hdl.handle.net/10251/34773.
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The present thesis employs fuzzy-polynomial control techniques in order to
improve the stability analysis and control of nonlinear systems. Initially, it
reviews the more extended techniques in the field of Takagi-Sugeno fuzzy systems,
such as the more relevant results about polynomial and fuzzy polynomial
systems. The basic framework uses fuzzy polynomial models by Taylor series
and sum-of-squares techniques (semidefinite programming) in order to obtain
stability guarantees.
The contributions of the thesis are:
¿ Improved domain of attraction estimation of nonlinear systems for both
continuous-time and discrete-time cases. An iterative methodology based
on invariant-set results is presented for obtaining polynomial boundaries
of such domain of attraction.
¿ Extension of the above problem to the case with bounded persistent disturbances
acting. Different characterizations of inescapable sets with
polynomial boundaries are determined.
¿ State estimation: extension of the previous results in literature to the
case of fuzzy observers with polynomial gains, guaranteeing stability of
the estimation error and inescapability in a subset of the zone where the
model is valid.
¿ Proposal of a polynomial Lyapunov function with discrete delay in order
to improve some polynomial control designs from literature. Preliminary
extension to the fuzzy polynomial case.
Last chapters present a preliminary experimental work in order to check
and validate the theoretical results on real platforms in the future.Pitarch Pérez, JL. (2013). Contributions to fuzzy polynomial techniques for stability analysis and control [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/34773
TESIS
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Devar, Madhrie. „An analysis of the attraction and retention of women in higher education institutions : a case study of the University of Pretoria and the University of KwaZulu-Natal“. Diss., University of Pretoria, 2017. http://hdl.handle.net/2263/60533.
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Human Resources have become a serious issue for present-day universities, as a result of the increased pressure from governments and global markets. The ability to attract and retain women in higher educational institutions has become a crucial challenge in terms of under-representation and gender equality. The study analyses the attraction and retention of women in higher educational institutions both in the University of KwaZulu-Natal and the University of Pretoria as case studies. For South Africa, it has become even more challenging; since South African universities have adopted drastic measures, in order to reform their systems over the past 20 years, and especially to meet the terms of socio-economic, political and equitable congruency.
Although many higher education institutions in South Africa have mission statements and equity plans to address the issues of attraction and retention, there is little that specifically targets women. The purpose of this study was to critically analyse the policy initiatives in place for the attraction and retention of women in higher educational institutions; to analyse the factors that drive the attraction and retention of women in higher education institutions; and to investigate the representation of women in senior academic and management positions, and to develop a framework for the attraction and retention of women in higher education institutions.
For the purpose of this study, human-resource strategies in terms of the attraction and retention of women and designated groups was scrutinised both for the universities under study and the higher educational policies in terms of the recruitment of women were identified and analysed.Dissertation (MAdmin)--University of Pretoria, 2017.
School of Public Management and Administration (SPMA)
MAdmin
Unrestricted
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Carranza, López José Camilo. „On the synchronization of two metronomes and their related dynamics /“. Ilha Solteira, 2017. http://hdl.handle.net/11449/151204.
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Orientador: Michael John BrennanResumo: Nesta tese são investigadas, teórica e experimentalmente, a sincronização em fase e a sincronização em anti-fase de dois metrônomos oscilando sobre uma base móvel, a partir de um modelo aqui proposto. Uma descrição do funcionamento do mecanismo de escapamento dos metrônomos é feita, junto a um estudo da relação entre este e o oscilador de van der Pol. Também uma aproximação experimental do valor do amortecimento do metrônomo é fornecida. A frequência instantânea das respostas, numérica e experimental, do sistema é usada na analise. A diferença de outros trabalhos prévios, os dados experimentais têm sido adquiridos usando vídeos dos experimentos e extraídos com ajuda do software Tracker. Para investigar a relação entre as condições iniciais do sistema e seu estado final de sincronização, foram usados mapas bidimensionais chamados ‘basins of attraction’. A relação entre o modelo proposto e um modelo prévio também é mostrada. Encontrou-se que os parâmetros relevantes em relação a ambos os tipos de sincronização são a razão entre a massa do metrônomo e a massa da base, e o amortecimento do sistema. Tem-se encontrado, tanto experimental quanto teoricamente, que a frequência de oscilação dos metrônomos aumenta quando o sistema sincroniza-se em fase, e se mantém a mesma de um metrônomo isolado quando o sistema sincroniza-se em anti-fase. A partir de simulações numéricas encontrou-se que, em geral, incrementos no amortecimento do sistema levam ao sistema se sincronizar mais em fase d... (Resumo completo, clicar acesso eletrônico abaixo)
Doutor
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Dimara, Evanthia. „Information Visualization for Decision Making : Identifying Biases and Moving Beyond the Visual Analysis Paradigm“. Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLS367/document.
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Certains problèmes ne peuvent être résolus ni par les ordinateurs seuls ni par les humains seuls. La visualisation d'information est une solution commune quand il est nécessaire de raisonner sur de grandes quantités de données. Plus une visualisation est efficace, plus il est possible de résoudre des problèmes complexes. Dans la recherche en visualisation d'information, une visualisation est généralement considérée comme efficace quand elle permet de comprendre les données. Les méthodes d'évaluation cherchent à déterminer si les utilisateurs comprennent les données affichées et sont capables d'effectuer des tâches analytiques comme, par exemple, identifier si deux variables sont corrélées. Cette thèse suggère d'aller au-delà de ce ``paradigme de l'analyse visuelle'' et élargir le champ de recherche à un autre type de tâche: la prise de décision. Les tâches de décision sont essentielles à tous, du directeur d'entreprise qui doit prendre des décisions importantes à l'individu ordinaire qui choisit un plan de carrière ou désire simplement acheter un appareil photo. Néanmoins, les décisions ne se résument pas à la simple compréhension de l'information et sont difficiles à étudier. Elles peuvent impliquer des préférences subjectives, n'ont pas toujours de vérité de terrain, et dépendent souvent de connaissances externes aux données visualisées. Pourtant, les tâches de décision ne font pas partie des taxonomies de tâches en visualisation et n'ont pas été bien définies. De plus, la recherche manque de métriques, de méthodes et de travaux empiriques pour valider l'efficacité des visualisations pour la prise de décision. Cette thèse offre une définition opérationnelle pour une classe particulière de tâches de décision, et présente une analyse systématique qui identifie les visualisations multidimensionnelles compatibles avec ces tâches. Elle présente en outre la première comparaison empirique de techniques de visualisation multidimensionnelle basée sur leur capacité à aider la décision, et esquisse une méthodologie et des métriques pour évaluer la qualité des décisions. Elle explore ensuite le rôle des instructions dans les tâches de décision et des tâches analytiques équivalentes, et identifie des différences de performance entre les deux tâches. De même que les sciences de la vision informent la visualisation d'information sur les limites de la vision humaine, aller au-delà du paradigme de l'analyse visuelle implique de prendre en compte les limites du raisonnement humain. Cette thèse passe en revue la théorie de la décision afin de mieux comprendre comment les humains prennent des décisions, et formule une nouvelle taxonomie de biais cognitifs basée sur la tâche utilisateur. En outre, elle démontre empiriquement que des biais peuvent être présents même quand l'information est bien visualisée, et qu'une décision peut être ``correcte'' mais néanmoins irrationnelle, dans le sens où elle est influencée par des informations non pertinentes. Cette thèse examine finalement comment mitiger les biais. Les méthodes pour améliorer le raisonnement humain reposent souvent sur un entraînement intensif à des principes et à des procédures abstraites, qui se révèlent souvent peu efficaces. Les visualisations offrent une opportunité dans la mesure où ses concepteurs peuvent remodeler l'environnement pour changer la façon dont les utilisateurs assimilent les données. Cette thèse passe en revue la théorie de la décision pour identifier de possibles solutions de conception. De plus, elle démontre empiriquement que supplémenter une visualisation par des interactions qui facilitent des stratégies de décision alternatives peut mener à des décisions plus rationnelles. Via des études empiriques, cette thèse suggère que le paradigme de l'analyse visuelle n'est pas en mesure de relever tous les défis de la prise de décision aidée de la visualisation, mais qu'aller au-delà peut contribuer à faire de la visualisation un puissant outil de prise de décisionThere are problems neither humans nor computers can solve alone. Computer-supported visualizations are a well-known solution when humans need to reason based on a large amount of data. The more effective a visualization, the more complex the problems that can be solved. In information visualization research, to be considered effective, a visualization typically needs to support data comprehension. Evaluation methods focus on whether users indeed understand the displayed data, can gain insights and are able to perform a set of analytic tasks, e.g., to identify if two variables are correlated. This dissertation suggests moving beyond this "visual analysis paradigm" by extending research focus to another type of task: decision making. Decision tasks are essential to everybody, from the manager of a company who needs to routinely make risky decisions to an ordinary person who wants to choose a career life path or simply find a camera to buy. Yet decisions do not merely involve information understanding and are difficult to study. Decision tasks can involve subjective preferences, do not always have a clear ground truth, and they often depend on external knowledge which may not be part of the displayed dataset. Nevertheless, decision tasks are neither part of visualization task taxonomies nor formally defined. Moreover, visualization research lacks metrics, methodologies and empirical works that validate the effectiveness of visualizations in supporting a decision. This dissertation provides an operational definition for a particular class of decision tasks and reports a systematic analysis to investigate the extent to which existing multidimensional visualizations are compatible with such tasks. It further reports on the first empirical comparison of multidimensional visualizations for their ability to support decisions and outlines a methodology and metrics to assess decision accuracy. It further explores the role of instructions in both decision tasks and equivalent analytic tasks, and identifies differences in accuracy between those tasks. Similarly to vision science that informs visualization researchers and practitioners on the limitations of human vision, moving beyond the visual analysis paradigm would mean acknowledging the limitations of human reasoning. This dissertation reviews decision theory to understand how humans should, could and do make decisions and formulates a new taxonomy of cognitive biases based on the user task where such biases occur. It further empirically shows that cognitive biases can be present even when information is well-visualized, and that a decision can be ``correct'' yet irrational, in the sense that people's decisions are influenced by irrelevant information. This dissertation finally examines how biases can be alleviated. Current methods for improving human reasoning often involve extensive training on abstract principles and procedures that often appear ineffective. Yet visualizations have an ace up their sleeve: visualization designers can re-design the environment to alter the way people process the data. This dissertation revisits decision theory to identify possible design solutions. It further empirically demonstrates that enriching a visualization with interactions that facilitate alternative decision strategies can yield more rational decisions. Through empirical studies, this dissertation suggests that the visual analysis paradigm cannot fully address the challenges of visualization-supported decision making, but that moving beyond can contribute to making visualization a powerful decision support tool
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Ilicheva, Elena. „Discounts as a marketing tool for attraction and retention of customers in e-commerce through the example of a comparative analysis of the specificity of fashion e-shops in Russia and Sweden“. Thesis, Högskolan i Borås, Akademin för textil, teknik och ekonomi, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:hb:diva-838.
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This study provides a comparative analysis of pricing promotions, which create an incentive to buy in Russian and Swedish fashion e-shops. The aim of this work is to determine the national differences in sales promotions used in e-commerce in these countries. This work confirms the existence of modern marketing trend in the e-commerce, which uses discounts as a tool for communication with consumers and for retaining them in the shop as a regular customer, and not just for traditional use of discounts as a way to sell remaining goods. To conduct the study the collected data obtained through systematic observation of application of discounts and promotions as marketing tools in the e-shops in these countries. Following the comparative analysis of statistical data we were able to determine the difference in the periods of sales, the maximum and minimum level of price falls, to create a typology of discounts, typical for both countries and for each of them separately. The recommendations for online retailers who develop the markets of these countries with regard to national specifics in communication with the consumer and based on the most popular types of discounts and promotions are also the important part of this work. The results of this study refute the words of the expert Simonetta Carbonaro that the modern approach to pricing policy in the e-commerce is a "suicide of fashion retail."
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Boore, Graeme C. „Directed graph iterated function systems“. Thesis, University of St Andrews, 2011. http://hdl.handle.net/10023/2109.
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This thesis concerns an active research area within fractal geometry. In the first part, in Chapters 2 and 3, for directed graph iterated function systems (IFSs) defined on ℝ, we prove that a class of 2-vertex directed graph IFSs have attractors that cannot be the attractors of standard (1-vertex directed graph) IFSs, with or without separation conditions. We also calculate their exact Hausdorff measure. Thus we are able to identify a new class of attractors for which the exact Hausdorff measure is known. We give a constructive algorithm for calculating the set of gap lengths of any attractor as a finite union of cosets of finitely generated semigroups of positive real numbers. The generators of these semigroups are contracting similarity ratios of simple cycles in the directed graph. The algorithm works for any IFS defined on ℝ with no limit on the number of vertices in the directed graph, provided a separation condition holds. The second part, in Chapter 4, applies to directed graph IFSs defined on ℝⁿ . We obtain an explicit calculable value for the power law behaviour as r → 0⁺ , of the qth packing moment of μ[subscript(u)], the self-similar measure at a vertex u, for the non-lattice case, with a corresponding limit for the lattice case. We do this (i) for any q ∈ ℝ if the strong separation condition holds, (ii) for q ≥ 0 if the weaker open set condition holds and a specified non-negative matrix associated with the system is irreducible. In the non-lattice case this enables the rate of convergence of the packing L[superscript(q)]-spectrum of μ[subscript(u)] to be determined. We also show, for (ii) but allowing q ∈ ℝ, that the upper multifractal q box-dimension with respect to μ[subscript(u)], of the set consisting of all the intersections of the components of F[subscript(u)], is strictly less than the multifractal q Hausdorff dimension with respect to μ[subscript(u)] of F[subscript(u)].
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Bergsten, Johannes. „Taxonomy, phylogeny, and secondary sexual character evolution of diving beetles, focusing on the genus Acilius“. Doctoral thesis, Umeå : Univ., Ekologi, miljö och geovetenskap, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-527.
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Grievink, Liat Shavit. „Lineage specific evolution and phylogenetic analysis : a thesis presented in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Biomathematics at Massey University, Palmerston North, New Zealand“. Massey University, 2009. http://hdl.handle.net/10179/1048.
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Phylogenetic models generally assume a homogeneous, time reversible, stationary process. These assumptions are often violated by the real, far more complex, evolutionary process. This thesis is centered on non-homogeneous, lineage-specific, properties of molecular sequences. It consist several related but independent studies. LineageSpecificSeqgen, an extension to the Seq-Gen program, which allows generation of sequences with changes in the proportion of variable sites, is introduced. This program is then used in a simulation study showing that changes in the proportion of variable sites can hinder tree estimation accuracy, and that tree reconstruction under the best-fit model chosen using a relative test can result in a wrong tree. In this case, the less commonly used absolute model-fit was a better predictor of tree estimation accuracy. This study found that increased taxon sampling of lineages that have undergone a change in the proportion of variable sites was critical for accurate tree reconstruction and that, in contrast to some earlier findings, the accuracy of maximum parsimony is adversely affected by such changes. This thesis also addresses the well-known long-branch attraction artifact. A nonparametric bootstrap test to identify changes in the substitution process is introduced, validated, and applied to the case of Microsporidia, a highly reduced intracellular parasite. Microsporidia was first thought to be an early branching eukaryote, but is now believed to be sister to, or included within, fungi. Its apparent basal eukaryote position is considered a result of long-branch attraction due to an elevated evolutionary rate in the microsporidian lineage. This study shows that long-branch estimates and basal positioning of Microsporidia both correlate with increased proportions of radical substitutions in the microsporidian lineage. In simulated data, such increased proportions of radical substitutions leads to erroneous long-branch estimates. These results suggest that the long microsporidian branch is likely to be a result of an increased proportion of radical substitutions on that branch, rather than increased evolutionary rate per se. The focus of the last study is the intriguing case of Mesostigma, a fresh water green alga for which contradicting phylogenetic relationships were inferred. While some studies placed Mesostigma within the Streptophyta lineage (which includes land plants), others placed it as the deepest green algae divergence. This basal positioning is regarded as a result of long-branch attraction due to poor taxon sampling. Reinvestigation of a 13- taxon mitochondrial amino acid dataset and a sub-dataset of 8 taxa reveals that site sampling, and in particular the treatment of missing data, is just as important a factor for accurate tree reconstruction as taxon sampling. This study identifies a difficulty in recreating the long-branch attraction observed for the 8-taxon dataset in simulated data. The cause is likely to be the smaller number of amino acid characters per site in simulated data compared to real data, highlighting the fact that there are properties of the evolutionary process that are yet to be accurately modeled.
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ConceiÃÃo, Ilze Eneida Paris da. „Potencial do turismo internacional de Cabo Verde“. Universidade Federal do CearÃ, 2014. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=14466.
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CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel SuperiorAo longo dos anos, o turismo internacional vem crescendo rapidamente ao ponto de ser considerado a maior indÃstria do mundo, com contribuiÃÃes significativas na economia e no desenvolvimento de pequenos paÃses. Cabo Verde à um pequeno Estado insular, composto por dez ilhas, especializado na indÃstria do turismo, com forte Ãnfase na demanda turistica internacional. Considerando que o turismo internacional tem grande participaÃÃo no produto interno bruto e no setor de serviÃos de Cabo Verde, à essencial que o paÃs continue a atrair e reter turistas para apoiar o desenvolvimento da economia e do paÃs. Para isso, à necessÃrio saber o que influencia a demanda turÃstica internacional no paÃs. Destarte, o objetivo da pesquisa à analisar o potencial do mercado turÃstico internacional de Cabo Verde, com destaque para a capacidade de atraÃÃo da demanda internacional e a anÃlise da competitividade turÃstica das ilhas que compÃem o arquipÃlago. Trata-se de uma pesquisa analÃtica, com enfoque quantitativo, utilizando dados secundÃrios fornecidos pelo Instituto Nacional de EstatÃstica de Cabo Verde e pelo Banco Central de Cabo Verde. Os dados foram analisados no software estatÃstico Eviews7Â, por meio de um modelo economÃtrico autorregressivo. Calcularam-se ainda Ãndices de preferÃncia e de saturaÃÃo turÃstica das ilhas de Cabo Verde, assim como suas quotas de mercado. Os resultados mostraram que a demanda turÃstica internacional por Cabo Verde à influenciada positivamente pela oferta hoteleira, pelo fluxo turÃstico passado e pela taxa de cÃmbio. Os Ãndices de preferÃncia turÃstica indicam que as ilhas do Sal e da Boavista sÃo as que mais atraem turistas em Cabo Verde, mas tambÃm apresentam problemas de saturaÃÃo turÃstica, o que pode culminar em danos sociais e ambientais. Conclui-se que Cabo Verde reflete problemas de saturaÃÃo turÃstica, o que mostra a necessidade de planejamento integrado e detalhado no sentido de minimizar problemas sociais e ambientais, bem como direcionar investimentos para ilhas preteridas, inovando para tornÃ-las atrativas de modo que possam contribuir para o desenvolvimento e a formulaÃÃo de estratÃgias que promovam o turismo sustentÃvel no paÃs.
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González, Germán Iván Temoatzin. „Contributions to analysis and control of Takagi-Sugeno systems via piecewise, parameter-dependent, and integral Lyapunov functions“. Doctoral thesis, Universitat Politècnica de València, 2018. http://hdl.handle.net/10251/101282.
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Esta tesis considera un enfoque basado en Lyapunov para el análisis y control de sistemas no lineales cuyas ecuaciones dinámicas son reescritas como un modelo Takagi-Sugeno o uno polinomial convexo. Estas estructuras permiten resolver problemas de control mediante técnicas de optimización convexa, más concretamente desigualdades matriciales lineales y suma de cuadrados, que son eficientes herramientas desde un punto de vista computacional. Después de proporcionar una visión general básica del estado actual en el campo de los modelos Takagi-Sugeno, esta tesis aborda cuestiones sobre las funciones de Lyapunov por trozos, dependiente de parámetros e integral de línea, con las siguientes contribuciones:
Un algoritmo mejorado para estimaciones del dominio de atracción de sistemas no lineales para sistemas de tiempo continuo. Los resultados se basan en funciones de Lyapunov por trozos, desigualdades matriciales lineales y argumentaciones geométricas; enfoques basados en conjuntos de nivel en la literatura previa se han mejorado significativamente.
Una función Lyapunov generalizada dependiente de parámetros para la síntesis de controladores para sistemas Takagi-Sugeno. El enfoque propone una ley de control multi-índice que retroalimenta la derivada del tiempo de las funciones de membresía del modelo Takagi-Sugeno para anular los términos que causan localidad a priori en el análisis de Lyapunov.
Una nueva función integral de Lyapunov para el análisis de estabilidad de sistemas no lineales. Estos resultados generalizan aquellos basados en funciones de Lyapunov integral de línea al marco polinomial; resulta que los requisitos de independencia del camino pueden ser anulados por una definición adecuada de una función Lyapunov con términos integrales.This thesis considers a Lyapunov-based approach for analysis and control of nonlinear systems whose dynamical equations are rewritten as a Takagi-Sugeno model or a convex polynomial one. These structures allow solving control problems via convex optimisation techniques, more specifically linear matrix inequalities and sum-of-squares, which are efficient tools from the computational point of view. After providing a basic overview of the state of the art in the field of Takagi-Sugeno models, this thesis address issues on piecewise, parameter-dependent and line-integral Lyapunov functions, with the following contributions: An improved algorithm to estimate the domain of attraction of nonlinear systems for continuous-time systems. The results are based on piecewise Lyapunov functions, linear matrix inequalities, and geometrical argumentations; level-set approaches in prior literature are significantly improved. A generalised parameter-dependent Lyapunov function for synthesis of controllers for Takagi-Sugeno systems. The approach proposed a multi-index control law that feeds back the time derivative of the membership function of the Takagi-Sugeno model to cancel out the terms that cause a priori locality in the Lyapunov analysis. A new integral Lyapunov function for stability analysis of nonlinear systems. These results generalise those based on line-integral Lyapunov functions to the polynomial framework; it turns out path-independency requirements can be overridden by an adequate definition of a Lyapunov function with integral terms.
Aquesta tesi considera un enfocament basat en Lyapunov per a l'anàlisi i control de sistemes no lineals les equacions dinàmiques dels quals són reescrites com un model Takagi-Sugeno o un de polinomial convex. Aquestes estructures permeten resoldre problemes de control mitjançant tècniques d'optimització convexa, més concretament desigualtats matricials lineals i suma de quadrats, que són eines eficients des d'un punt de vista computacional. Després de proporcionar una visió general bàsica de l'estat actual en el camp dels models Takagi-Sugeno, aquesta tesi aborda qüestions sobre les funcions de Lyapunov per trossos, dependent de paràmetres i integral de línia, amb les següents contribucions: Un algoritme millorat per a estimar el domini d'atracció de sistemes no lineals per a sistemes de temps continu. Els resultats es basen en funcions de Lyapunov per trossos, desigualtats matricials lineals i argumentacions geomètriques; enfocaments basats en conjunts de nivell en la literatura prèvia s'han millorat significativament. Una funció Lyapunov generalitzada dependent de paràmetres per a la síntesi de controladors per a sistemes Takagi-Sugeno. L'enfocament proposa una llei de control multi-índex que retroalimenta la derivada del temps de les funcions de membres del model Takagi-Sugeno per anul·lar els termes que causen localitat a priori en l'anàlisi de Lyapunov. Una nova funció integral de Lyapunov per a l'anàlisi d'estabilitat de sistemes no lineals. Aquests resultats generalitzen aquells basats en funcions de Lyapunov integral de línia al marc polinomial; resulta que els requisits d'independència del camí poden ser anul·lats per una definició adequada d'una funció Lyapunov amb termes integrals.
González Germán, IT. (2018). Contributions to analysis and control of Takagi-Sugeno systems via piecewise, parameter-dependent, and integral Lyapunov functions [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/101282
TESIS
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Fassoni, Artur César. „Sistemas dinâmicos: bacias de atração e aplicações“. Universidade Federal de Viçosa, 2012. http://locus.ufv.br/handle/123456789/4917.
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The present work proposes to present a description of the theory on the basins of attraction of hyperbolic equilibrium points of continuous dynamical systems, to develop a method for the numerical determination of these basins and to examine the results of applying the theory and method in models of population dynamics. The determination of the basins of attraction allows the study of control strategies on the parameters, in order to increase or decrease such regions, as interest. From the biological phenomena viewpoint, these predictions are very important, because if an equilibrium point represents the extinction of a species that must be preserved, then one seeks to guarantee that the natural initial conditions do not are in the basin of attraction of that point. This is made by studying control strategies on the parameters, for that the point basin decreases suficiently. From the viewpoint of stability analysis of equilibrium points of dynamical systems, the theory of basins of attraction brings topological consequences to the phase space which allow, indirectly, conduct a global analysis in the parameters space, allowing wider results of which are generally obtained without this theory.
O presente trabalho propõe-se a apresentar uma descrição da teoria sobre as bacias de atração de pontos de equilíbrio hiperbólicos de sistemas dinâmicos em tempo contínuo, a desenvolver um método para a determinação numérica dessas bacias e a examinar os resultados da aplicação da teoria e do método em modelos de dinâmica de populações. A determinação das bacias de atração permite o estudo de estratégias de controle sobre os parâmetros, de modo a aumentar ou diminuir tais regiões, conforme o interesse. Do ponto de vista de fenômenos biológicos, estas previsões são importantes, pois, se um ponto de equilíbrio representa a extinção de uma espécie que deve ser preservada, então procura-se garantir que as condições iniciais naturais não estejam na bacia de atração do mesmo, estudando-se estratégias de controle sobre os parâmetros para que a bacia do ponto diminua suficientemente. Do ponto de vista da análise de estabilidade dos pontos de equilíbrio de um sistema, a teoria de bacias de atração traz consequências topológicas ao espaço de fase que permitem, de forma indireta, realizar uma análise global, no espaço de parâmetros, da estabilidade dos pontos de equilíbrio, garantindo resultados mais amplos dos que se obtêm geralmente, quando não se faz uso desta teoria.
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Chikhaoui, Khaoula. „Conception robuste de structures périodiques à non-linéarités fonctionnelles“. Thesis, Bourgogne Franche-Comté, 2017. http://www.theses.fr/2017UBFCD029/document.
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L’analyse dynamique des structures de grandes dimensions incluant de nombreux paramètres incertains et des non-linéarités localisées ou réparties peut être numériquement prohibitive. Afin de surmonter ce problème, des modèles d’approximation peuvent être développés pour reproduire avec précision et à faible coût de calcul la réponse de la structure.L’objectif de la première partie de ce mémoire est de développer des modèles numériques robustes vis-à-vis des modifications structurales (non-linéarités localisées, perturbations ou incertitudes paramétriques) et « légers » au sens de la réduction de la taille. Ces modèles sont construits, selon les approches de condensation directe et par synthèse modale, en enrichissant des bases de réduction tronquées, modale et de Craig-Bampton respectivement, avec des résidus statiques prenant compte des modifications structurales. Pour propager les incertitudes, l’accent est mis particulièrement sur la méthode du chaos polynomial généralisé. Sa combinaison avec les modèles réduits ainsi obtenus permet de créer des métamodèles mono et bi-niveaux, respectivement. Les deux métamodèles proposés sont comparés à d’autres métamodèles basés sur les méthodes du chaos polynomial généralisé et du Latin Hypercube appliquées sur des modèles complets et réduits. Les métamodèles proposés permettent d’approximer les comportements structuraux avec un coût de calcul raisonnable et sans perte significative de précision.La deuxième partie de ce mémoire est consacrée à l’analyse dynamique des structures périodiques non-linéaires en présence des imperfections : perturbations des paramètres structuraux ou incertitudes paramétriques. Deux études : déterministe ou stochastique, respectivement, sont donc menées. Pour ces deux configurations, un modèle analytique discret générique est proposé. Il consiste à appliquer la méthode des échelles multiples et la méthode de perturbation pour résoudre l’équation de mouvement et de projecter la solution obtenue sur des modes d’ondes stationnaires. Le modèle proposé conduit à un ensemble d’équations algébriques complexes couplées, fonctions du nombre et des positions des imperfections dans la structure. La propagation des incertitudes à travers le modèle ainsi construit est finalement assurée par les méthodes du Latin Hypercube et du chaos polynomial généralisé. La robustesse de la dynamique collective vis-à-vis des imperfections est étudiée à travers l’analyse statistique de la dispersion des réponses fréquentielles et des bassins d’attraction dans le domaine de multistabilité. L’étude numérique montre que la présence des imperfections dans une structure périodique renforce sa non-linéarité, élargit son domaine de multistabilité et génère une multiplicité de branches multimodaleDynamic analysis of large scale structures including several uncertain parameters and localized or distributed nonlinearities may be computationally unaffordable. In order to overcome this issue, approximation models can be developed to reproduce accurately the structural response at a low computational cost.The purpose of the first part of this thesis is to develop numerical models which must be robust against structural modifications (localized nonlinearities, parametric uncertainties or perturbations) and reduce the size of the initial problem. These models are created, according to the direct condensation and the component mode synthesis, by enriching truncated reduction modal bases and Craig-Bampton transformations, respectively, with static residual vectors accounting for the structural modifications. To propagate uncertainties through these first-level and second-level reduced order models, respectively, we focus particularly on the generalized polynomial chaos method. This methods combination allows creating first-level and second-level metamodels, respectively. The two proposed metamodels are compared to other metamodels based on the polynomial chaos method and Latin Hypercube method applied on reduced and full models. The proposed metamodels allow approximating the structural behavior at a low computational cost without a significant loss of accuracy.The second part of this thesis is devoted to the dynamic analysis of nonlinear periodic structures in presence of imperfections: parametric perturbations or uncertainties. Deterministic or stochastic analyses, respectively, are therefore carried out. For both configurations, a generic discrete analytical model is proposed. It consists in applying the multiple scales method and the perturbation theory to solve the equation of motion and then on projecting the resulting solution on standing wave modes. The proposed model leads to a set of coupled complex algebraic equations, depending on the number and positions of imperfections in the structure. Uncertainty propagation through the proposed model is finally done using the Latin Hypercube method and the generalized polynomial chaos expansion. The robustness the collective dynamics against imperfections is studied through statistical analysis of the frequency responses and the basins of attraction dispersions in the multistability domain. Numerical results show that the presence of imperfections in a periodic structure strengthens its nonlinearity, expands its multistability domain and generates a multiplicity of multimodal branches
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Forsthoefel, David J. „A molecular genetic analysis of the role of the Guanine Nucleotide Exchange Factor Trio during Axon Pathfinding in the Embryonic CNS of Drosophila melanogaster“. Connect to resource, 2005. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1127241654.
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Ben, Abdallah Emna. „Étude de la dynamique des réseaux biologiques : apprentissage des modèles, intégration des données temporelles et analyse formelle des propriétés dynamiques“. Thesis, Ecole centrale de Nantes, 2017. http://www.theses.fr/2017ECDN0041.
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Au cours des dernières décennies, l’émergence d’une large gamme de nouvelles technologies a permis de produire une quantité massive de données biologiques (génomique, protéomique...). Ainsi, une grande quantité de données de séries temporelles est maintenant élaborée tous les jours. Nouvellement produites, ces données peuvent nous fournir des nouvelles interprétations sur le comportement des Systèmes Biologiques (SB). Cela conduit alors à des développements considérables dans le domaine de la bioinformatique qui peuvent tirer profit de ces données. Ceci justifie notre motivation pour le développement de méthodes efficaces qui exploitent ces données pour l’apprentissage des Réseaux de Régulation Biologique (RRB) modélisant les SB. Nous introduisons alors, dans cette thèse, une nouvelle approche qui infère des RRB à partir des données de séries temporelles. Les RRB appris sont présentés avec un nouveau formalisme, introduit dans cette thèse, appelé " réseau d’automates avec le temps" (T-AN). Ce dernier assure le raffinement de la dynamique des RRB, modélisés avec le formalisme des réseaux d’automates (AN), grâce à l’intégration d’un paramètre temporel (délai) dans les transitions locales des automates. Cet enrichissement permet de paramétrer les transitions entre les états locaux des automates et aussi entre les états globaux du réseau. À posteriori de l’apprentissage des RRB, et dans le but d’avoir une meilleure compréhension de la nature du fonctionnement des SB, nous procédons à l’analyse formelle de la dynamique des RRB. Nous introduisons alors des méthodes logiques originales (développées en Answer Set Programming) pour déchiffrer l’énorme complexité de la dynamique des SB. Les propriétés dynamiques étudiées sont : l’identification des attracteurs (ensemble d’états globaux terminaux dont le réseau ne peut plus s’échapper) et la vérification de la propriété d’atteignabilité d’un objectif (un ensemble de composants) à partir d’un état global initial du réseauOver the last few decades, the emergence of a wide range of new technologies has produced a massive amount of biological data (genomics, proteomics...). Thus, a very large amount of time series data is now produced every day. The newly produced data can give us new ideas about the behavior of biological systems. This leads to considerable developments in the field of bioinformatics that could benefit from these enormous data. This justifies the motivation to develop efficient methods for learning Biological Regulatory Networks (BRN) modeling a biological system from its time series data. Then, in order to understand the nature of system functions, we study, in this thesis, the dynamics of their BRN models. Indeed, we focus on developing original and scalable logical methods (implemented in Answer Set Programming) to deciphering the emerging complexity of dynamics of biological systems. The main contributions of this thesis are enumerated in the following. (i) Refining the dynamics of the BRN, modeling with the automata Network (AN) formalism, by integrating a temporal parameter (delay) in the local transitions of the automata. We call the extended formalism a Timed Automata Network (T-AN). This integration allows the parametrization of the transitions between each automata local states as well as between the network global states. (ii) Learning BRNs modeling biological systems from their time series data. (iii) Model checking of discrete dynamical properties of BRN (modeling with AN and T-AN) by dynamical formal analysis : attractors identification (minimal trap domains from which the network cannot escape) and reachability verification of an objective from a network global initial state