To see the other types of publications on this topic, follow the link: Stability theory[Forking theory].
Dissertations / Theses on the topic 'Stability theory[Forking theory]'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Stability theory[Forking theory].'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Wagner, Frank O. "Stable groups and generic types." Thesis, University of Oxford, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.258015.
Full text
2
Pourmahdian, M. "Model theory of simple theories." Thesis, University of Oxford, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.325836.
Full text
3
Craft, Colin N. "On Morley's Categoricity Theorem with an Eye Toward Forking." Miami University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=miami1323475348.
Full text
4
Potier, Joris. "A few things about hyperimaginaries and stable forking." Doctoral thesis, Universitat de Barcelona, 2015. http://hdl.handle.net/10803/394029.
Full textAbstract:
The core of this PhD dissertation is basically twofold :
On one hand, I get some new results on the relationship between compact groups and bounded hyperimaginaries, extending a little bit the classical results of Lascar and Pillay in Hyperimaginaries And Automorphism Groups.
On the other hand, I prove some new results around the so called "stable forking" property, more specifically that a simple theory T has stable forking if Teq has. Quite surprisingly, the proof is not so straigtforward.En este texto se trata, por una parte, de la relación entre grupos compactos e hiper-imaginarios acotados, y por otra parte se prueba que una teoría T tiene la propiedad de bifurcación estable si i solo si Teq la tiene.
5
Farina, John Dominic. "Stability properties in ring theory." Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2006. http://wwwlib.umi.com/cr/ucsd/fullcit?p3237384.
Full textAbstract:
Thesis (Ph. D.)--University of California, San Diego, 2006.Title from first page of PDF file (viewed December 8, 2006). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references (p. 86-90).
6
Tsaparas, Panayiotis. "Stability in adversarial queueing theory." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp04/mq28768.pdf.
Full text
7
Haykazyan, Levon. "Aspects of nonelementary stability theory." Thesis, University of Oxford, 2016. https://ora.ox.ac.uk/objects/uuid:940cd0bf-e4bb-4074-a521-d3c139d16743.
Full textAbstract:
This thesis aims to contribute to neostability and in particular to the stability theory of nonelementary classes. The central themes of the thesis are quasiminimality and excellence. We explore both classical and geometric aspects of stability theory for such classes. In particular our methods aim to utilise the topology on the space of types in these settings. Chapter 1 is introductory and sets the necessary background on nonelementary classes. In Chapter 2 we use infinitary methods to study quasiminimal excellent classes. We give a simplified proof of the Categoricity Theorem. In Chapter 3 we study quasiminimality from the first order perspective. We look for conditions on a first order theory that allow us to build quasiminimal models with various additional properties. In Chapter 4 we look at excellent groups. We aim to generalise various results from (geometric) stability theory to this nonelementary setting.
8
Palacín, Cruz Daniel. "Forking in simple theories and CM-triviality." Doctoral thesis, Universitat de Barcelona, 2012. http://hdl.handle.net/10803/84023.
Full textAbstract:
Aquesta tesi té tres objectius. En primer lloc, estudiem generalitzacions de la jerarquia no ample relatives a una família de tipus parcials. Aquestes jerarquies en permeten classificar la complexitat del “forking” respecte a una família de tipus parcials. Si considerem la família de tipus algebraics, aquestes generalitzacions corresponen a la jerarquia ordinària, on el primer i el segon nivell corresponen a one-basedness i a CM-trivialitat, respectivament. Fixada la família de tipus regulars “no one-based”, el primer nivell d'una d'aquestes possibles jerarquies no ample ens diu que el tipus de la base canònica sobre una realització és analitzable en la família. Demostrem que tota teoria simple amb suficients tipus regulars pertany al primer nivell de la jerarquia dèbil relativa a la família de tipus regulars no one-based. Aquest resultat generalitza una versió dèbil de la “Canonical Base Property” estudiada per Chatzidakis i Pillay.
En segon lloc, discutim problemes d'eliminació de hiperimaginaris assumint que la teoria és CM-trivial, en tal cas la independència del “forking” té un bon comportament. Més concretament, demostrem que tota teoria simple CM-trivial elimina els hiperimaginaris si elimina els hiperimaginaris finitaris. En particular, tota teoria petita simple CM-trivial elimina els hiperimaginaris. Cal remarcar que totes les teories omega-categòriques simples que es coneixen són CM-trivials; en particular, aquelles teories obtingudes mitjançant una construcció de Hrushovski.
Finalment, tractem problemes de classificació en les teories simples. Estudiem la classe de les teories simples baixes; classe que inclou les teories estables i les teories supersimples de D-rang finit. Demostrem que les teories simples amb pes finit acotat també pertanyen a aquesta classe. A més, provem que tota teoria omega-categòrica simple CM-trivial és baixa. Aquest darrer fet resol parcialment una pregunta formulada per Casanovas i Wagner.The development of first-order stable theories required two crucial abstract notions: forking independence, and the related notion of canonical base. Forking independence generalizes the linear independence in vector spaces and the algebraic independence in algebraically closed fields. On the other hand, the concept of canonical base generalizes the field of definition of an algebraic variety. The general theory of independence adapted to simple theories, a class of first-order theories which includes all stable theories and other interesting examples such as algebraically closed fields with an automorphism and the random graph. Nevertheless, in order to obtain canonical bases for simple theories, the model-theoretic development of hyperimaginaries --equivalence classes of arbitrary tuple modulo a type-definable (without parameters) equivalence relation-- was required. In the present thesis we deal with topics around the geometry of forking in simple theories. Our first goal is to study generalizations of the non ample hierarchy which will code the complexity of forking with respect to a family of partial types. We introduce two hierarchies: the non (weak) ample hierarchy with respect to a fixed family of partial types. If we work with respect to the family of bounded types, these generalizations correspond to the ordinary non ample hierarchy. Recall that in the ordinary non ample hierarchy the first and the second level correspond to one-basedness and CM-triviality, respectively. The first level of the non weak ample hierarchy with respect to some fixed family of partial types states that the type of the canonical base over a realization is analysable in the family. Considering the family of regular non one-based types, the first level of the non weak ample hierarchy corresponds to the weak version of the Canonical Base Property studied by Chatzidakis and Pillay. We generalize Chatzidakis' result showing that in any simple theory with enough regular types, the canonical base of a type over a realization is analysable in the family of regular non one-based types. We hope that this result can be useful for the applications; for instance, the Canonical Base Property plays an essential role in the proof of Mordell-Lang for function fields in characteristic zero and Manin-Mumford due to Hrushovski. Our second aim is to use combinatorial properties of forking independence to solve elimination of hyperimaginaries problems. For this we assume the theory to be simple and CM-trivial. This implies that the forking independence is well-behaved. Our goal is to prove that any simple CM-trivial theory which eliminates finitary hyperimaginaries --hyperimaginaries which are definable over a finite tuple-- eliminates all hyperimaginaries. Using a result due to Kim, small simple CM-trivial theories eliminate hyperimaginaries. It is worth mentioning that all currently known omega-categorical simple theories are CM-trivial, even those obtained by an ab initio Hrushovski construction. To conclude, we study a classification problem inside simple theories. We study the class of simple low theories, which includes all stable theories and supersimple theories of finite D-rank. In addition, we prove that it also includes the class of simple theories of bounded finite weight. Moreover, we partially solve a question posed by Casanovas and Wagner: Are all omega-categorical simple theories low? We solve affirmatively this question under the assumption of CM-triviality. In fact, our proof exemplifies that the geometry of forking independence in a possible counterexample cannot come from finite sets.
9
De, Bruyne Peter J. J. "Aspects of solar coronal stability theory." Thesis, University of St Andrews, 1991. http://hdl.handle.net/10023/14071.
Full textAbstract:
Solar coronal stability theory is a powerful tool for understanding the complex behaviour of the Sun's atmosphere. It enables one to discover the driving forces behind some intriguing phenomena and to gauge the soundness of theoretical models for observed structures. In this thesis, the linear stability analysis of line-tied symmetric magnetohydrostatic equilibria is studied within the framework of ideal MHD, aimed at its application to the solar corona. Firstly, a tractable stability procedure based on a variational method is devised. It provides a necessary condition for stability to disturbances localised about a particular flux surface, and a sufficient condition for stability to all accessible perturbations that vanish at the photosphere. The tests require the minimisation of a line integral along the magnetic field lines. For 1-D equilibria, this can be performed analytically, and simple stability criteria are obtained. The necessary condition then serves as an extended Suydam criterion, incorporating the stabilising effect of line-tying. For 2-D equilibria, the minimisation requires the integration of a system of ordinary differential equations along the field lines. This stability technique is applied to arcade, loop, and prominence models, yielding tight bounds on the equilibrium parameters. Secondly, global modes in 1-D coronal loops are investigated using a normal mode method, in order to clarify their link with localised interchange modes. For nearly force-free fields it is shown that instability to localised modes implies the existence of a fast growing global kink mode driven in the neighbourhood of the radius predicted by the local analysis. This confers a new significance on the study of localised interchange modes and the associated extended Suydam criterion.
10
Cerri, Andrea <1978>. "Stability and computation in multidimensional size theory." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2007. http://amsdottorato.unibo.it/562/.
Full text
11
Dagbovie, Ayawoa. "Applications of stability theory to ecological problems." Thesis, Heriot-Watt University, 2013. http://hdl.handle.net/10399/2795.
Full textAbstract:
The goal of ecology is to investigate the interactions among organisms and their environment. However, ecological systems often exhibit complex dynamics. The application of mathematics to ecological problems has made tremendous progress over the years and many mathematical methods and tools have been developed for the exploration, whether analytical or numerical, of these dynamics. Mathematicians often study ecological systems by modelling them with partial differential equations (PDEs). Calculating the stability of solutions to these PDE systems is a classical question. This thesis first explores the concept of stability in the context of predator-prey invasions. Many ecological systems exhibit multi-year cycles. In such systems, invasions have a complicated spatiotemporal structure. In particular, it is common for unstable steady states to exist as long-term transients behind the invasion front, a phenomenon known as dynamical stabilisation. We combine absolute stability theory and computation to predict how the width of the stabilised region depends on parameter values. We develop our calculations in the context of a model for a cyclic predator-prey system, in which the invasion front and spatiotemporal oscillations of predators and prey are separated by a region in which the coexistence steady state is dynamically stabilised. Vegetation pattern formation in water-limited environments is another topic where stability theory plays a key role; indeed in mathematical models, these patterns are often the results of the dynamics that arise from perturbations to an unstable homogeneous steady state. Vegetation patterns are widespread in semi-deserts and aerial photographs of arid and semi-arid ecosystems have shown several kilometers square of these patterns. On hillsides in particular, vegetation is organised into banded spatial patterns. We first choose a domain in parameter space and calculate the boundary of the region in parameter space where pattern solutions exist. Finally we conclude with investigating how changes in the mean annual rainfall affect the properties of pattern solutions. Our work also highlights the importance of research on the calculation of the absolute spectrum for non-constant solutions.
12
Bahsoon, Rami Khalil. "Evaluating architectural stability with real options theory." Thesis, University College London (University of London), 2006. http://discovery.ucl.ac.uk/1445303/.
Full textAbstract:
Evolution is a key problem in software engineering and exacts huge costs. Industrial evidence even hints that companies spend more resources on maintaining and evolving their software than on the initial development. In managing the change and guiding evolution, considerable emphasis is placed on the architecture of the software system as a key artifact involved. One of the major indicators of the success (failure) of software evolution is the extent to which the software system can endure changes in requirements, while leaving the architecture of the software system intact. We refer to the presence of this "intuitive" phenomenon as architectural stability. We highlight the requirements for evaluating architectural stability. We pursue an economics-driven software engineering approach to address these requirements. We view evolving software as a value-seeking activity: software evolution is as a process in which software is undergoing a change (an incremental) and seeking value. The value is attributed to the flexibility of an architecture in enduring likely changes in requirements. To value flexibility, we contribute to a novel model that builds on an analogy with real options theory. The model examines some likely changes in requirements and values the extent to which the architecture is flexible to endure these changes. The model views an investment in an architecture as an upfront investment plus "continual" increments of future investments in likely changes in requirements. The objective is to provide insights into architectural stability and investment decisions related to the evolution of software architectures. We support the model with a three-phase method for evaluating architectural stability. The method provides guidelines on eliciting the likely changes in requirements and relating architectural decisions to value. The problem of valuing flexibility of an architecture to change requires a comprehensive solution that incorporates multiple valuation techniques, some with subjective estimates, and others based on market data, when available. To introduce discipline into this setting and capture the value from different perspectives, the method outlines a valuation points of view framework as a solution. The framework is flexible enough to account for the economic ramifications of the change on both structural (e.g., maintainability) and behavioral (e.g., throughput) qualities of an architecture and on relevant business goals (e.g., new market products). We report on our experience in using the model and its supporting method with two case studies. In the first case, we show how the model and its supporting method can be used to assess the worthiness of re-engineering a "more" stable architecture in face of likely changes in future requirements. We take refactoring as an example of re-engineering. In the second case, we show how the model and its supporting method can inform the selection of a "more" stable middleware-induced software architecture in the face of future changes in non-functional requirements. We critically discuss and reflect on the strengths and the limitations of our contribution. We conclude by highlighting some open questions that could stimulate future research in architectural stability, relating requirements to software architectures, and architectural economics.
13
Luo, Xiao 1975. "Information, knowledge, and stability : essays in game theory." Thesis, McGill University, 2000. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=36778.
Full textAbstract:
This dissertation contains three essays in game theory, focusing particularly on the issues of information, knowledge, and stability in complex interactions. It begins with an introductory overview.Chapter 2 offers a general framework for analyzing complex economic and social environments. Specifically, I introduce new notions of a general system and a ϕ-stable set. By making use of Tarski's fixed point theorem, I then establish the existence of a ϕ-stable set. I further apply the proposed notions to game theory, e.g., rationalizability is derived from the largest ϕ-stable set.
Chapter 3 establishes epistemic foundations for the criterion of "stability." Specifically, in strategic games, achieving common knowledge of rationality (CKR) implies an internally ϕ-stable set that is contained in an externally ϕ-stable set and, moreover, whenever mutually known, a ϕ-stable set is implied by rationality alone. In the case of two-person games, achieving CKR implies a ϕ-stable set. In extensive games with perfect information, achieving CKR implies a unique ϕ-stable set. On the other hand, in both strategic and extensive games, any of the commonly known ϕ-stable sets implies CKR. Furthermore, any ϕ-stable set can be achieved in terms of CKR.
Chapter 4 presents a new solution concept of stable equilibrium in beliefs (SEB) by assuming it is common knowledge that players are uncertainty averse. By making use of an appealing criterion of "stability," an SEB is defined as a strategy profile supported by a stable belief system. It is shown that all SEBs constitute a unique stable belief system, and an SEB satisfies subgame perfectness; moreover, it is shown that the notion of SEB "refines" that of subgame perfect equilibrium in terms of path of play. Finally, we establish the epistemic foundation for the notion of SEB.
14
Sofer, Miguel Marcelo. "On equilibrium, stability and nonlocality in elasticity theory /." [S.l.] : [s.n.], 1991. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=9420.
Full text
15
Choi, Yam-ming Kelvin. "Use of block theory in tunnel stability analysis /." View the Table of Contents & Abstract, 2006. http://sunzi.lib.hku.hk/hkuto/record/B36616710.
Full text
16
Magyari-Köpe, Blanka. "Structural stability of solids from first principles theory." Doctoral thesis, KTH, Physics, 2002. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3366.
Full text
17
Choi, Yam-ming Kelvin, and 蔡任明. "Use of block theory in tunnel stability analysis." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2006. http://hub.hku.hk/bib/B45014358.
Full text
18
Rogers, Thomas Alexander. "Feedback and stability theory for linear multipass processes." Thesis, University of Sheffield, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.385814.
Full text
19
Coombs-Reyes, Jerome D. "Customer allocation policies in a two server network stability and exact asymptotics /." Diss., Available online, Georgia Institute of Technology, 2004:, 2003. http://etd.gatech.edu/theses/available/etd-03292004-141826/unrestricted/coombs-reyes%5Fjerome%5Fd%5F200312%5Fphd.pdf.
Full text
20
Alva, Samson. "Essays on Matching Theory and Networks." Thesis, Boston College, 2013. http://hdl.handle.net/2345/bc-ir:104379.
Full textAbstract:
Thesis advisor: Utku UnverThis dissertation is composed of three essays in microeconomic theory. The first and second essays are in the theory of matching, with hierarchical organizations and complementarities being their respective topic. The third essay is in on electoral competition and political polarization as a result of manipulation of public opinion through social influence networks. Hierarchies are a common organizational structure in institutions. In the first essay, I offer an explanation of this fact from a matching-theoretic perspective, which emphasizes the importance of stable outcomes for the persistence of organizational structures. I study the matching of individuals (talents) via contracts with institutions, which are aggregate market actors, each composed of decision makers (divisions) enjoined by an institutional governance structure. Conflicts over contracts between divisions of an institution are resolved by the institutional governance structure, whereas conflicts between divisions across institutions are resolved by talents' preferences. Stable market outcomes exist whenever institutional governance is hierarchical and divisions consider contracts to be bilaterally substitutable. In contrast, when governance in institutions is non-hierarchical, stable outcomes may not exist. Since market stability does not provide an impetus for reorganization, the persistence of markets with hierarchical institutions can thus be rationalized. Hierarchies in institutions also have the attractive incentive property that in a take-it-or-leave-it bargaining game with talents making offers to institutions, the choice problem for divisions is straightforward and realized market outcomes are pairwise stable, and stable when divisions have substitutable preferences. Complementarity has proved to be a challenge for matching theory, because the core and group stable matchings may fail to exist. Less well understood is the more basic notion of pairwise stability. In a second essay, I define a class of complementarity, asymmetric complements, and show that pairwise stable matchings are guaranteed to exist in matching markets where no firm considers workers to be asymmetric complements. The lattice structure of the pairwise stable matchings, familiar from the matching theory with substitutes, does not survive in this more general domain. The simultaneous-offer and sequential-offer versions of the worker-proposing deferred acceptance algorithm can produce different matchings when workers are not necessarily substitutable. If no firm considers workers to be imperfect complements, then the simultaneous-offer version produces a pairwise stable matching, but this is not necessarily true otherwise. If no firm considers workers to be asymmetric complements, a weaker restriction than no imperfect complements, then the sequential-offer version produces a pairwise stable matching, though the matching produced is order-dependent. In a third essay, I examine electoral competition in which two candidates compete through policy and persuasion, and using a tractable two-dimensional framework with social learning provide an explanation for increasing political polarization. Voters and candidates have policy preferences that depend upon the state of the world, which is known to candidates but not known to voters, and are connected through a social influence network that determines through a learning process the final opinion of voters, where the voters' initial opinions and the persuasion efforts of the candidates affect final opinions, and so voting behavior. Equilibrium level of polarization in policy and opinion (of both party and population) increases when persuasion costs decrease. An increase in homophily increases the equilibrium level of policy polarization and population opinion polarization. These comparative static results help explain the increased polarization in both the policy and opinion dimensions in the United States
Thesis (PhD) — Boston College, 2013
Submitted to: Boston College. Graduate School of Arts and Sciences
Discipline: Economics
21
Sallam, M. H. M. "Aspects of stability and bifurcation theory for multiparameter problems." Thesis, University of Strathclyde, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.371969.
Full text
22
Wei, Mengyang. "Study of the banking system's stability using control theory." Thesis, University of Kent, 2017. https://kar.kent.ac.uk/61734/.
Full textAbstract:
The 2007-2009 financial meltdown reflected the failure of the regulators to address financial fragility and it has clearly showed that regulating banks on an individual basis was an ineffective approach to prevent financial crises. Before the crisis, financial regulation was primarily focused on managing the risk of individual banks by requiring them to keep sufficient reserves to safeguard themselves from the inherent risk of their own investments. Since they ignored the risks that are generated by links between the banks, i.e. interbank borrowing and lending, a failure in a small number of banks could spread to other banks, and cause the paralysis of the whole banking system. Therefore, there is the need to give special emphasis to systemic risk, rather than consider the risk at an individual level. From an academic research point of view, the 2007-2009 financial crisis renewed the interest in finding new ways of studying financial systems. More specifically, since then new modelling frameworks have been proposed that incorporate the interconnected nature of the banking system. Network models have been used to investigate the stability of the banking system under different conditions, e.g. different banks' size and connectivity. This thesis proposes a new dynamic network model based on ordinary differential equations, which represents the banking system and seeks to interface the network model approach with control engineering. Control theory is an interdisciplinary branch of engineering, which is used to study the behaviour of dynamical systems, and how their behaviour can be modified by feedback mechanisms to achieve a desirable performance. In this work control theory is applied for the first time to analyse a model of the banking system and to propose feedback mechanisms, which preserve the stability of the system and that can ultimately inform financial regulators.
23
Takahashi, Tomohiro. "Stability Analysis of Black Hole Solutions in Lovelock Theory." 京都大学 (Kyoto University), 2013. http://hdl.handle.net/2433/175117.
Full text
24
Huertas, Chacon Marco Antonio. "Applications of effective field theory/density functional theory to ground-state properties of nuclei far from stability." W&M ScholarWorks, 2003. https://scholarworks.wm.edu/etd/1539623424.
Full textAbstract:
The applicability of a new approach, developed by Furnstahl, Serot and Tang, to describe the nuclear many-body system is studied for nuclei far from stability. This approach combines elements of effective field theory (EFT) and density functional theory (DFT) and has already been tested in the stability region. In this thesis, several steps are taken to address the question of the applicability of the EFT/DFT formulation to nuclei far from stability. First the convergence of the approach is studied by applying it directly to selected doubly-magic nuclei far from stability. An independently developed code, which can incorporate various levels of approximation of the chiral effective lagrangian, is used to solve the self-consistent relativistic Hartree equations. This program is used to obtained results for ground-state properties such as binding energies, single-particle level structure, and densities of the doubly-magic nuclei 132,100Sn and 48,78Ni. Second, the accuracy of the calculation of the ground-state density is indirectly studied by using the single-particle (Kohn-Sham) wave functions to calculate weak transitions. The weak currents used correspond to the Noether currents derived from the effective lagrangian. The calculations use a general expression for single-particle transition matrix elements, derived here, from which any semi-leptonic weak rate can be calculated. Attention is focused on beta-decay processes in nuclei neighboring 132Sri and the results are compared with available experimental data. Finally calculations are extended to determine total binding energies and single-particle and single-hole binding energies, spins, and parities for isotopes with magic numbers N = 28, 50, 82, 126, and isotopes with Z = 28, 50, 82. The results of this thesis indicate that the EFT/DFT formulation of Furnstahl, Serot and Tang is capable of reproducing the relevant ground-state binding energies to within 1%, chemical-potentials with an average accuracy of 10%, and ground-state spins and parities, at least if the neutron level density is not too high.
25
Feyzbakhsh, Soheyla. "Bridgeland stability conditions, stability of the restricted bundle, Brill-Noether theory and Mukai's program." Thesis, University of Edinburgh, 2018. http://hdl.handle.net/1842/31485.
Full textAbstract:
In [Bri07], Bridgeland introduced the notion of stability conditions on the bounded derived category D(X) of coherent sheaves on an algebraic variety X. This topic is originally inspired by concepts in string theory and mathematical physics and has many interesting applications in algebraic geometry. In the first part of the thesis, we provide a direct proof of an important result in [Bri08, BMS16] which states there is a two dimensional family of weak Bridgeland stability conditions on the bounded derived category D(X) of coherent sheaves on a variety X. As a first application of this result, we prove an effective restriction theorem which provides sufficient conditions on a stable locally free sheaf on a projective variety such that its restriction to a hypersurface remains stable. Secondly, we extend and complete Mukai's program to reconstruct a K3 surface from a curve on that surface. We show that the K3 surface containing the curve can be obtained uniquely as a Fourier-Mukai partner of a suitable Brill-Noether locus of vector bundles on the curve.
26
Xue, Licun. "Coalitional stability in strategic situations." Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=40287.
Full textAbstract:
In many (social, economic, and political) strategic situations, conflict and cooperations coexist and group (or coalitional) behavior is as important as individual behavior. This dissertation studies several issues in such situations.Chapter 1 provides an overview of the theoretical background and motivates the analysis undertaken.
Chapter 2 analyzes strategic situations with diverse coalitional interactions to ascertain the "stable" outcomes that will not be replaced by any rational (hence farsighted) coalition of individuals, and the coalitions that are likely to form. The analysis takes into full account the perfect foresight of rational individuals, which has been overlooked in the literature.
Chapter 3 defines "negotiation-proof Nash equilibrium", a notion that applies to environments where players can negotiate openly and directly prior to the play of a noncooperative game. The merit of the notion of negotiation-proof Nash equilibrium is twofold: (1) It resolves the nestedness and myopia embedded in the notion of coalition-proof Nash equilibrium. (2) The negotiation process, which is formalized by a "graph", serves as a natural alternative to the approach that models pre-play communication by an extensive form game.
Chapter 4 examines the notion of "renegotiation-proofness" in infinitely repeated games. It is shown that imposing renegotiation in all contingencies creates both conceptual and technical difficulties. A notion of self-enforcing agreements is offered: an agreement is self-enforcing if it is immune to any deviation by any coalition which cannot (confidently) count on renegotiation.
27
Ranjan, Pawas. "Discrete Laplace Operator: Theory and Applications." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1343832381.
Full text
28
Wadee, Mohammad Khurram. "Elements of a Lagrangian theory of localized buckling." Thesis, Imperial College London, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.325494.
Full text
29
August, Elias. "Stability and dissipativity theory for nonnegative and compartmental dynamical systems." Thesis, Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/13068.
Full text
30
Stonier, D. J., and mikewood@deakin edu au. "Stability theory and numerical analysis of non-autonomous dynamical systems." Deakin University. School of Information Technology, 2003. http://tux.lib.deakin.edu.au./adt-VDU/public/adt-VDU20051125.113243.
Full textAbstract:
The development and use of cocycles for analysis of non-autonomous behaviour is a technique that has been known for several years. Initially developed as an extension to semi-group theory for studying rion-autonornous behaviour, it was extensively used in analysing random dynamical systems [2, 9, 10, 12].
Many of the results regarding asymptotic behaviour developed for random dynamical systems, including the concept of cocycle attractors were successfully transferred and reinterpreted for deterministic non-autonomous systems primarily by P. Kloeden and B. Schmalfuss [20, 21, 28, 29]. The theory concerning cocycle attractors was later developed in various contexts specific to particular classes of dynamical systems [6, 7, 13], although a comprehensive understanding of cocycle attractors (redefined as pullback attractors within this thesis) and their role in the stability of non-autonomous dynamical systems was still at this stage incomplete.
It was this purpose that motivated Chapters 1-3 to define and formalise the concept of stability within non-autonomous dynamical systems. The approach taken incorporates the elements of classical asymptotic theory, and refines the notion of pullback attraction with further development towards a study of pull-back stability arid pullback asymptotic stability. In a comprehensive manner, it clearly establishes both pullback and forward (classical) stability theory as fundamentally unique and essential components of non-autonomous stability. Many of the introductory theorems and examples highlight the key properties arid differences between pullback and forward stability. The theory also cohesively retains all the properties of classical asymptotic stability theory in an autonomous environment. These chapters are intended as a fundamental framework from which further research in the various fields of non-autonomous
dynamical systems may be extended.
A preliminary version of a Lyapunov-like theory that characterises pullback attraction is created as a tool for examining non-autonomous behaviour in Chapter 5. The nature of its usefulness however is at this stage restricted to the converse theorem of asymptotic stability.
Chapter 7 introduces the theory of Loci Dynamics. A transformation is made to an alternative dynamical system where forward asymptotic (classical asymptotic) behaviour characterises pullback attraction to a particular point in the original dynamical system. This has the advantage in that certain conventional techniques for a forward analysis may be applied.
The remainder of the thesis, Chapters 4, 6 and Section 7.3, investigates the effects of perturbations and discretisations on non-autonomous dynamical systems known to possess structures that exhibit some form of stability or attraction. Chapter 4 investigates autonomous systems with semi-group attractors, that have been non-autonomously perturbed, whilst Chapter 6 observes the effects of discretisation on non-autonomous dynamical systems that exhibit properties of forward asymptotic stability. Chapter 7 explores the same problem of discretisation, but for pullback asymptotically stable systems. The theory of Loci Dynamics is used to analyse the nature of the discretisation, but establishment of results directly analogous to those discovered in Chapter 6 is shown to be unachievable. Instead a case by case analysis is provided for specific classes of dynamical systems, for which the results generate a numerical approximation of the pullback attraction in the original continuous dynamical system.
The nature of the results regarding discretisation provide a non-autonomous extension to the work initiated by A. Stuart and J. Humphries [34, 35] for the numerical approximation of semi-group attractors within autonomous systems. . Of particular importance is the effect on the system's asymptotic behaviour over non-finite intervals of discretisation.
31
Pearce, S. P. "Bifurcation and stability of elastic membranes : theory and biological applications." Thesis, Keele University, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.518311.
Full text
32
Förster, Annette. "Decent peace, stability and justice : John Rawls's international theory applied." Thesis, London School of Economics and Political Science (University of London), 2012. http://etheses.lse.ac.uk/470/.
Full textAbstract:
John Rawls’s international theory, The Law of Peoples, has been read and criticized as “A Theory of International Justice”. His major objective, however, is not the establishment of a just (liberal) world order, but to guide liberal societies towards a reasonable peaceful, stable and just international system. From this starting point, the thesis assesses whether Rawls’s international theory can meet its task to function as a guideline for the promotion of international peace, stability and justice and how that peace might be conceived. The author argues that Rawls sketches the path to a “decent peace”. The scrutiny of the issue takes the form of an in-depth analysis and discussion of The Law of Peoples and a systematic investigation of a number of cases. The dissertation examines the possible contribution of Rawls’s ideas, primarily the Society of Peoples and the principles of the Law of Peoples, to international peace, stability and justice. As the focus lies on decent regimes and a decent peace, three actual decent societies are identified (Oman, Qatar and Singapore), in order to highlight the applicability of the notion to the international system, as well as to ensure that decent regimes are not mere constructions serving to justify imposing liberal principles of non-liberal regimes. The dissertation finally investigates the enlargement of the democratic peace thesis towards a decent peace; it discusses the arguments for a democratic peace and applies them to Rawls’s conception of decent peoples as well as to the identified regimes. It concludes asserting that the decent peace thesis is theoretically wellfounded, whereas the empirical evidence is – due to only three identified regimes – rather weak. As a guideline for the foreign policy of liberal (and decent) societies The Law of Peoples can contribute to more stability and justice in the international realm and promote a decent peace.
33
O'Rourke, Colm J. "Decentralized power systems : reference-frame theory and stability region generation." Thesis, Massachusetts Institute of Technology, 2020. https://hdl.handle.net/1721.1/127082.
Full textAbstract:
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, May, 2020Cataloged from the official PDF of thesis.
Includes bibliographical references (pages 87-91).
Electricity provides the foundation for many of today's technological advances. The desire for energy security, a reduction in carbon dioxide emissions and a diversification of resources are all motivations for changes in how electricity is generated and transmitted. Recent alternatives to traditional centralized power-plants include technologies that are decentralized and intermittent, such as solar photovoltaic and wind power. This trend poses considerable challenges in the hardware making up these systems, the software that control and monitor power networks and their mathematical modelling. This thesis presents a set of contributions that address some of the aforementioned challenges. Firstly, we examine the fundamental theories used in modelling and controlling power systems. We expand previous work on reference-frame theory, by providing an alternative interpretation and derivation of the commonly used Park and Clarke transformations. We present a geometric interpretation that has applications in power quality. Secondly, we introduce a framework for producing regions of stability for power systems using conditional generative adversarial neural networks. This provides transmission and distribution operators with an accurate set of control options even as the system changes significantly.
by Colm J. O'Rourke.
Ph. D.
Ph.D. Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science
34
Mulzet, Alfred Kenric. "Exponential Stability for a Diffusion Equation in Polymer Kinetic Theory." Diss., Virginia Tech, 1997. http://hdl.handle.net/10919/30473.
Full textAbstract:
In this paper we present an exponential stability result for a
diffusion equation arising from dumbbell models for
polymer flow. Using the methods of semigroup theory, we
show that the semigroup U(t) associated with the diffusion
equation is well defined and that all solutions converge
exponentially to an equilibrium solution. Both finitely and
infinitely extensible dumbbell models are considered. The
main tool in establishing stability is the proof of
compactness of the semigroup.Ph. D.
35
Mihirig, Ali Mohamed. "Transient stability analysis of multimachine power systems by catastrophe theory." Thesis, University of British Columbia, 1987. http://hdl.handle.net/2429/29022.
Full textAbstract:
Transient stability analysis is an important part of power system planning and operation. For large power systems, such analysis is very demanding in computation time. On-line transient stability assessment will be necessary for secure and reliable operation of power systems in the near future because systems are operated close to their maximum limits.
In the last two decades, a vast amount of research work has been done in the area of fast transient stability assessment by direct methods. The major difficulties associated with direct methods are the limitations in the power system model, determination of transient stability regions and adaptation to changes in operating conditions. In this thesis catastrophe theory is used to determine the transient stability regions. Taylor series expansion is used to find the energy balance equation in terms of clearing time and system transient parameters. The energy function is then put in the form of a catastrophe manifold from which the bifurcation set is extracted. The bifurcation set represents the transient stability region in terms of the power system transient parameters bounded by the transient stability limits. The transient stability regions determined are valid for any changes in loading conditions and fault location. The transient stability problem is dealt with in the two dimensions of transient stability limits and critical clearing times. Transient stability limits are given by the bifurcation set and the critical clearing times are calculated from the catastrophe manifold equation. The method achieves a breakthrough in the modelling problem because the effects of exciter response, flux decay and systems damping can all be included in the transient stability analysis. Numerical examples of one-machine infinite-bus and multi-machine power systems show very good agreement with the time solution in the practical range of first swing stability analysis. The method presented fulfills all requirements for on-line assessment of transient stability of power systems.Applied Science, Faculty of
Electrical and Computer Engineering, Department of
Graduate
36
Matros, Alexander. "Stochastic stability and equilibrium selection in games." Doctoral thesis, Stockholm : Economic Research Institute, Stockholm School of Economics (Ekonomiska forskningsinstitutet vid Handelshögsk.) (EFI), 2001. http://www.hhs.se/efi/summary/571.htm.
Full text
37
徐善強 and Sin-keung Chui. "Stability and bifurcation in flow induced vibration." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1997. http://hub.hku.hk/bib/B31235724.
Full text
38
Chui, Sin-keung. "Stability and bifurcation in flow induced vibration /." Hong Kong : University of Hong Kong, 1997. http://sunzi.lib.hku.hk/hkuto/record.jsp?B1904155X.
Full text
39
Atalayer, Senem Hayriye. "Analysis Of Stability And Transition In Flat Plate Compressible Boundary Layers Using Linear Stability Theory." Master's thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/2/12605366/index.pdf.
Full textAbstract:
In this study, numerical investigations of stability and transition problems were performed for 2D compressible boundary layers over a flat plate in adiabatic wall condition. Emphasis was placed on linear stability theory. The mathematical formulation for 3D boundary layers with oblique waves including detailed theoretical information was followed by use of the numerical techniques for the solution of resulting differential system of the instability problem, consequently an eigenvalue problem.
First, two-dimensional sinusoidal disturbances were analyzed at various Mach numbers including the subsonic, transonic, supersonic and even hypersonic flow speeds. In this case, the second mode (acoustic mode), namely the Mack mode, and its behavior with the increasing Mach number were visualized. The results were then compared with the available data in literature concluding with good agreements.
Secondly, similar analysis was carried out for oblique waves. Here, not only the effect of flow speed but also the effect of wave orientation was demonstrated. For this purpose, instability problem was solved for several wave angles at each Mach number in the range of M=0 and M=5. In this respect, the angle at which the waves were most unstable was also obtained at each investigated flow speed. The resultant stability diagrams corresponding to M=4 and higher Mach numbers for which both first and the second modes appear revealed that plane waves were more stable than oblique waves for the Tollmien-Schlichting mode, however, this was the opposite for the acoustic mode where oblique waves were observed to be more stable.
As a final step, estimation of the transition location was handled for the most unstable wave condition. Smith-Van Ingen transition method was applied as the prediction device. The results representing the influence of Mach number on transition Reynolds number were then compared with the experimental data as well as the numerical ones in literature ending up with very good agreements.
40
Chow, Po Chung. "Moral stability and liberal justification : an examination of the notion of stability in Rawls' theory." Thesis, London School of Economics and Political Science (University of London), 2006. http://etheses.lse.ac.uk/2802/.
Full textAbstract:
This thesis offers a comprehensive examination of the notion of moral stability in Rawls's political philosophy. I argue that the problem of stability is essentially concerned with the motivational priority of a sense of justice. A conception of justice is justified if and only if it can effectively motivate rational agents to act as justice requires. It is a constitutive condition of justifiability rather than a practical matter of feasibility. I vindicate my claim through a philosophical interpretation of Rawls's account of practical reason for action. I then contend that stability plays an essential role in Rawls's two stage justification. At the first stage, taking place in the original position, stability is one of the main grounds for Rawls's principles. Nevertheless, I argue that the motive for contractors to adopt the maximin rule stems from moral considerations rather than an egoistic rational choice. At the second stage, the question of how to reconcile justice and goodness arises. We need to consider whether the regulative desire to act justly is congruent with a person's own good. This concern leads to Rawls's congruence argument through a Kantian interpretation of human nature. I suggest that this interpretation has turned Rawls into a liberal perfectionist within a classical teleological framework - a position inconsistent with Rawls's desire-based conception of prudential rationality. It is this internal inconsistency which makes the congruence argument fundamentally flawed. I then turn to examine political liberalism and point out that the idea of an overlapping consensus fails to justify the priority of political values over non-political ones. Finally, I propose an idea of potential congruence to support justice as fairness as a stable conception of justice. I conclude that this is the right direction to resolve the problem of stability and justification.
41
Jennings, Otis Brian. "Multiclass queueing networks with setup delays : stability analysis and heavy traffic approximation." Diss., Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/25190.
Full text
42
Hasenbein, John Jay. "Stability, capacity, and scheduling of multiclass queueing networks." Diss., Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/24836.
Full text
43
Liu, Fang. "Forced convection in curved ducts multiplicity and stability /." Click to view the E-thesis via HKUTO, 2006. http://sunzi.lib.hku.hk/hkuto/record/B37015837.
Full text
44
Kubelec, Christopher J. "Macroeconomic policy and stability in international financial markets." Thesis, University of Warwick, 2005. http://wrap.warwick.ac.uk/2458/.
Full textAbstract:
This thesis examines two key areas where macroeconomic policy and stability in international financial markets intersect. Part one examines the extent to which economic policy can limit the development of misalignments in exchange rates, without sacrificing policy tools that are needed to maintain internal macroeconomic balance. This issue is addressed in a model where endogenous exchange rate fluctuations are generated by traders selecting alternative forecasting strategies on the basis of an ‘evolutionary fitness rule’, in the spirit of work by Brock and Hommes (1997, 1998). In this setting it is shown how, by changing the relative profitability of available strategies, sterilized intervention can coordinate traders onto strategies based on macroeconomic fundamentals. Empirical evidence in support of the model is provided based on data from interventions by the Japanese authorities in the 1990’s. In addition, simulations of the estimated model are used to calculate confidence intervals for the ex ante probability that interventions of a given size will be effective in pricking bubbles in the exchange rate. Part two moves on to examine the implications for macroeconomic policy of the exponential growth in recent years of the use of financial derivatives. A theoretical model is developed which demonstrates how firms’ use of derivatives for risk management purposes, while increasing the robustness of the financial system to shocks, at the same time reduces the impact of monetary policy on the macroeconomy. This effect arises because the agency costs, which enhance the impact of monetary policy through the credit channel, are reduced by firms’ usage of hedging instruments, in particular interest rate swaps. Using quarterly data on total outstanding swap contracts from 1990, empirical evidence is then presented to show how increased usage of derivatives may have influenced the impact of monetary policy in the United States.
45
Galanis, Giorgos. "Heterogeneous economies : implications for inequality and financial stability." Thesis, University of Warwick, 2017. http://wrap.warwick.ac.uk/92769/.
Full textAbstract:
In the first chapter we explore the relationship between income inequality and the Utilitarian ethic in a dynamic environment with endogenous preferences. Classical Utilitarians, like Bentham, believed that utilitarian principles are compatible with egalitarian ones. Although this claim is not uncontroversial, this relation holds for a utilitarian distribution of a given good among people, with identical concave utilities and exogenously set preferences. This idea breaks down if the preferences are different. In this paper we allow for endogenous preferences influenced by the existence of habits. We show how the inclusion of habit formation, studied in a dynamic environment, has egalitarian implications for a classical utilitarian distribution. Based on this result we are able to argue that Bentham’s positive views of decreasing inequality due to different consumption habits are consistent with his normative views regarding distribution. The second chapter explores the question of whether long-term income inequality consistent with equality of opportunity (EOp) ethic. In order to provide an answer we study the effectiveness of intergenerational EOp policies in an environment with two social groups and infinite generations of individuals, where the outcomes of one generation define the circumstances of the next. Circumstances in this paper have to do either with different preferences among individuals from different social groups or with both resources and preferences due to these resources. We show that in the former case EOp policies reduce inequality and also the EOp policy is the same as the Utilitarian one. In the latter case, inequality is not reduced and its level depends on the relative population of the two social groups. The third chapter studies an economy where privately informed hedge funds trade a risky asset in order to exploit potential mispricings. Hedge funds are allowed to have access to credit, by using their risky assets as collateral. We analyse the role of the degree of heterogeneity among hedge funds’s demand for the risky asset in the emergence of clustering of defaults. We find that fire-sales caused by margin calls is a necessary, yet not a sufficient condition for defaults to be clustered. We show that when the degree of heterogeneity is sufficiently high, poorly performing hedge funds are able to obtain a higher than usual market share at the end of the leverage cycle, which leads to an improvement of their performance. Consequently, their survival time is prolonged, increasing the probability of them remaining in operation until the downturn of the next leverage cycle. This leads to the increase of the probability of poorly and high-performing hedge funds to default in sync at a later time, and thus the probability of collective defaults.
46
Asık, Gunes. "Empirical essays on employment, financial development and stability." Thesis, London School of Economics and Political Science (University of London), 2014. http://etheses.lse.ac.uk/1077/.
Full textAbstract:
This thesis is a collection of essays on the important problems in developing countries and aims to contribute to the empirical literature on the i) financial services sector expansion and its implications on formal employment, i) impact of early retirement incentives on labour force participation rates and finally on the iii) effectiveness of stabilization funds on reducing the boom and bust cycles in light of fluctuating international commodity prices. Chapter 1 investigates the role of financial services expansion, especially the impact of increase in consumer credits on the reduction of informal employment. I argue that liberalization should naturally lead to a decline in the share of informal employment due to the fact that international firms are less likely to employ informally and consumers whose borrowing constraints are relaxed due to more credit availability are more likely to prefer goods that are paid with consumer credits. I test this hypothesis by exploiting the regional variation in Turkey. Due to the possible endogeneity problem, I employ several instruments and find positive impact of consumer services expansion on formal employment. Two unique datasets that I explore for for possible instruments are i) the religiosity and political tendencies surveys of 2011 and 2013, and ii) regional Armenian population loss data between 1914-1917 in the former Ottoman Empire that preceded the Turkish Republic. The exogenous variation that I seek to explore accordingly are; i) Islam bans all sorts of interest charges in financial transactions and therefore residents of more conservative regions are on average less likely to demand consumer credits, and ii) Armenians were the trading and artisan class of the Empire and therefore the main users of the financial instruments and when they perished. Chapter 2 is about the impact of a Social Security System that allowed women and men to retire as early as 38 and 44 years old on labour supply decisions in Turkey. Before the pension reform of 1999, the Law 3774, dated 1992 brought incentives to those individuals who several conditions to retire at a much earlier age than the conventional 60-65 years window. Using the Statistics on Income and Living Condition (SILC) panel dataset between 2007-2010 in a Fuzzy Regression Continuity Design, we find that these incentives let to an average decline of about 16.9 hours in weekly hours worked by men aged 44-52 and 20.6 hours decline in weekly hours worked by women who are aged between 39-49 in a bandwidth of three years around the eligible age for retirement. Moreover, we find that the entitlement for retirement after 44 years old reduced the probability of labour force participation of men by about 28% to 37% while we did not find a statistically meaningful impact on the participation decisions of women. Chapter 3 explores whether sovereign wealth or stabilization funds created by governments in oil rich countries are effective in reducing volatility and ensuring a counter-cyclical or acyclical fiscal policy in line with the optimal fiscal policy literature or whether they are just another government account in practise. The existing literature on the effectiveness of stabilization funds suffers from endogeneity problems, namely i) the endogeneity between gdp and government expenditures and ii) the endogenity of the decision to establish stabilization funds. In this paper, I contribute to the literature by addressing both of these problems by using a series of Two Stage Least Square Estimations and find positive evidence in favour of stabilization funds in reducing volatility and pro-cyclicality of the fiscal policy in oil rich countries. The findings are relevant for the wider discussion of the procyclicality in developing countries, as one third of the countries which are documented to improve fiscal policy cyclicality seem to be the ones that are resource rich and have a stabilization fund in place.
47
Pu, Bing-Yin. "Studies on the stability of liquid/liquid dispersions : theory and practice /." Zürich, 1995. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=11315.
Full text
48
Assaf, Noura. "Consociational theory and democratic stability : a re-examination : case study, Lebanon." Thesis, University of Warwick, 2004. http://wrap.warwick.ac.uk/1203/.
Full textAbstract:
The present thesis re-assesses the utility of the theory of consociational democracy as a prescriptive conflict-regulation mechanism for plural societies, by re-examining the significance of the so-called causative/positive relationship between consociationalism and democratic stability. This re-assessment is based on a twin-fold examination of the internal constructs and logic of consociational theory, their political/economic procedural aspects and their societal manifestations. This examination is undertaken in two complex historical contexts, pre-war and post-war Lebanon. Mainly, the internal weaknesses of the theory have to do with its inherently flawed assumptions and the imprecise definitions of its main components, which make it problematic to analytically and empirically establish a causative link between consociationalism and democratic stability. Thus, to undertake a meaningful discussion of the ability of consociationalism to deliver on the promise of democratic stability, the thesis elaborates on the definitions of the main components and concepts of consociational theory (as they relate to the Lebanese context). It also examines their relations to democratic theory. Equally, starting with the observations that many countries of the world adopt consociational practices and mechanisms of rule and that consociational theory continues to receive significant scholarly attention, the continuous development and elaboration of the consociational model appear to be a way of alleviating the weaknesses of the theory and expanding its prescriptive power. Hence, particular emphasis is placed on an original elaboration of the definition, concept and representative scope of the grand coalition for two major reasons. First, this is so in the light of the centrality of the notion of elites and their role in consociational democracies (consociationalism being an actor-centered model). Second, this is the case in the light of the fact that executive decision-making power effectively lies within the ruling grand coalition. Based on the complex societal stage on which the thesis unfolds, (i. e., the Lebanese context), the findings of the thesis reveal that the consociational model of democracy is at times unable in very many ways to operate as the consociational theory of democracy suggests. Most importantly for the purposes of the present dissertation, the Lebanese experiments with consociationalism reveal that the model is unable at times to prevent the outbreak of communal conflict involving violence. Furthermore, it does not seem to work properly without a heavy dose of internal mediation and external arbitration. Additionally, it prevents the Lebanese state and social systems from reaching the political maturity necessary for stability. In other words, the Lebanese consociational structure of governance appears to work effectively at ensuring relative stability only if it is continuously assisted by additional mechanisms of conflict-regulation (those of mediation and arbitration). Indeed, the Lebanese consociational model functions relatively well when it borrows from the above-mentioned mechanisms provided by the literature on conflict regulation in plural societies. As such, consociationalism's so-called ability to deliver, alone, on the promise of democratic stability for Lebanon's plural society is seriously questioned.
49
Thomas, Neil B. "The analysis and control of nonlinear systems using Lyapunov stability theory." Thesis, This resource online, 1996. http://scholar.lib.vt.edu/theses/available/etd-08292008-063459/.
Full text
50
De, Brito Cardeliquio Caetano. "Contributions to the Theory of Time-Delay Systems : Stability and Stabilisation." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLC080/document.
Full textAbstract:
Le but de cette thèse est de présenter de nouveaux résultats sur l'analyse et la synthèse de systèmes à retard. Dans la première partie, nous étendons l'utilisation du système invariant d'ordre fini, appelé "système de comparaison", à la conception d'un contrôleur qui dépend non seulement de la sortie à l'heure actuelle et du délai maximum, mais également d'un nombre arbitraire de valeurs entre celles-ci. Cette approche nous permet d'augmenter le délai maximal stable sans exiger d'informations supplémentaires. Les méthodes présentées ici concernent la conception de systèmes de contrôle avec des retards en utilisant des routines numériques classiques basées sur la théorie Hoo. La deuxième partie de ce travail traite d'une nouvelle approche pour développer une enveloppe englobant tous les pôles d'un système à retard. Grâce aux LMIs, nous sommes en mesure de déterminer les enveloppes pour les systèmes à retard du type retardé et du type neutre. Les enveloppes proposées sont non seulement plus étroites que celles de la littérature, mais, avec notre procédure, elles peuvent également être appliquées pour vérifier la stabilité du système et pour projeter contrôleurs de retour d'état qui répondent aux exigences de conception relatives à alpha-stabilité et sont robustes face aux incertitudes paramétriques. Les systèmes fractionnaires sont également discutés dans les deux chapitres mentionnés ci-dessus. La troisième et dernière partie étudie les systèmes stochastiques avec des retards. Nous discutons d'abord des systèmes à temps continu soumis à des sauts de Markov. Nous définissons la stabilité et obtenons des LMIs pour le contrôle par retour d'état de telle sorte que la relation entre les taux de transition entre les modes soit affine, ce qui permet donc de traiter le cas dans lequel les taux sont incertains. Nous discutons ensuite des systèmes positifs avec retards, tant pour le cas continu que pour le cas discret. Des systèmes équivalents sont obtenus et la stabilité dépendante du retard est abordée. De nombreux exemples sont illustrés tout au long de la thèseThe aim of this dissertation is to present new results on analysis and control design of time-delay systems. On the first part, we extend the use of a finite order LTI system, called 'comparison system', to design a controller which depends not only on the output at the present time and maximum delay, but also on an arbitrary number of values between those. This approach allows us to increase the maximum stable delay without requiring any additional information. The methods presented here consider time-delay systems control design with classical numeric routines based on Hoo theory. The second part of this work deals with a new approach to develop an envelope that engulfs all poles of a time-delay system. Through LMIs, we are able to determine envelopes for retarded and neutral time-delay systems. The envelopes proposed are not only tighter than the ones in the literature but, with our procedure, they can also be applied to verify the stability of the system and design state-feedback controllers which cope with design requirements regarding alpha-stability and are robust in face of parametric uncertainties. Fractional systems are also discussed for both chapters mentioned above. The third and last part studies stochastic time-delay systems.First we discuss continuous-time systems that are subjected to Markov jumps. We define stability and obtain LMIs for the state-feedback control in such a way that the relation with the transition rates between the modes is affine, allowing, therefore, to treat the case in which the rates are uncertain. We then discuss positive systems with delays, both for the continuous case as for the discrete case. Equivalent systems are obtained and delay dependent stability is addressed. A fair amount of examples are presented throughout the dissertation