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Liakata, Maria. "Inducing domain theories". Thesis, University of Oxford, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.413107.
Testo completo
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Weibell, Christian J. "Principles of Learning: A Conceptual Framework for Domain-Specific Theories of Learning". BYU ScholarsArchive, 2011. https://scholarsarchive.byu.edu/etd/2759.
Testo completoAbstract (sommario):
This study is predicated on the belief that there does not now exist, nor will there ever exist, any single theory of learning that is broad enough to account for all types of learning yet specific enough to be maximally useful in practical application. Perhaps this dichotomy is the reason for the apparent gap between existing theories of learning and the practice of instructional design. As an alternative to any supposed grand theory of learning—and following the lead of prominent thinkers in the fields of clinical psychology and language teaching—this study proposes a shift toward principles. It presents a principle-based conceptual framework of learning, and recommends use of the framework as a guide for creating domain-specific theories of learning. The purpose of this study was to review theories of learning in the behavioral, cognitive, constructive, human, and social traditions to identify principles of learning local to those theories that might represent specific instances of more universal principles, fundamentally requisite to the facilitation of learning in general. Many of the ideas reviewed have resulted from, or been supported by, direct empirical evidence. Others have been suggested based on observational or practical experience of the theorist. The ideas come from different points in time, are described from a variety of perspectives, and emphasize different aspects and types of learning; yet there are a number of common themes shared among them regarding the means by which learning occurs. It is hypothesized that such themes represent universal and fundamental principles of learning. These principles were the objective of the present study. They have been sought through careful review and analysis of both theoretical and empirical literature by methods of textual research (Clingan, 2008) and constant comparative analysis (Glaser & Strauss, 1967). By way of textual research a methodological lens was defined to identify general themes, and by way of constant comparative analysis these themes were developed further through the analysis and classification of specific instances of those themes in the texts reviewed. Ten such principles were identified: repetition, time, step size, sequence, contrast, significance, feedback, context, engagement, and agency. These ten facilitative principles were then organized in the context of a comprehensive principles-of-learning framework, which includes the four additional principles of potential, target, change, and practice.
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LO, MONACO GABRIELE. "Duality walls and three-dimensional superconformal field theories". Doctoral thesis, Università degli Studi di Milano-Bicocca, 2020. http://hdl.handle.net/10281/257786.
Testo completoAbstract (sommario):
Un’importante classe di teorie 3d superconformi ammette una realizzazione in teoria delle stringhe e può essere ingegnerizzata usando configurazioni di D3, D5 ed NS5 brane, chiamate configurazioni di Hanany-Witten (HW). La dinamica a basse energie di queste teorie sono state ampiamente studiate in passato: un ruolo prominente è giocato dalla mirror symmetry, una dualità tra teorie che possiedono uguale punto fisso nell’infrarosso. Mirror symmetry può essere pensata come un’eredità dell’S-dualità in teoria di stringa. Come osservato da Gaiotto e Witten, le configurazioni di HW possono essere generalizzate aggiungendo nuovi oggetti, chiamati SL(2,Z) duality walls o S-fold. Passando attraverso questa interfaccia, il sistema subisce localmente una trasformazione SL(2,Z). Setup di HW con l’inserzione di un S-fold ammettono anche una descrizione olografica in supergravità di tipo IIB, come mostrato recentemente da Assel e Tomasiello. Da un punto di vista di teoria di campo, l’inserzione di un S-fold si manifesta come una teoria T[U(N)] in cui ogni fattore U(N) nel gruppo di simmetria U(N)x U(N) è gaugiato allo stesso tempo, generando un accoppiamento non banale tra due multipletti vettoriali. In questo senso, T[U(N)] gioca il ruolo di materia non convenzionale. Chiameremo S-fold SCFT una teoria con un accoppiamento T[U(N)] (T-link): queste teorie possono essere pensate come una generalizzazione degli usuali quiver circolari N=4. È importante sottolineare che solo un fattore U(N) del gruppo di simmetria è manifesto nella descrizione Lagrangiana di T[U(N)], mentre l’altro è emergete nell’infrarosso. Per tale motivo, un T-link aggiunge un elemento non-lagrangiano e lo studio delle teorie con S-fold risulta essere un’intrigante sfida da un punto di vista di QFT. Lo scopo di questa tesi è studiare in più dettaglio le S-fold SCFT. Ci concentreremo prevalentemente sullo spazio dei moduli, dualità e la supersimmetria preservata nell’infrarosso.
Lo strumento principale per studiare lo spazio dei moduli è la mirror symmetry. Quando tutti i livelli di Chern-Simons (CS) sono spenti, proponiamo che l’Higgs branch di queste teorie può essere calcolato effettuando un hyperKahler quotient. Inoltre, congetturiamo che il Coulomb branch coincide con il Coulomb branch di un quiver effettivo dove i nodi accoppiati dal T-link sono congelati. Chiamiamo questo fenomeno freezing rule e possiamo interpretarlo come l’impossibilità di una D3 brana di muoversi in certe direzioni nel caso in cui intersechi un S-fold. Generalizziamo anche le S-fold SCFT a casi più generali dove appare una teoria T[G], con G gruppo ortogonale, simplettico o eccezionale. Nel caso di G gruppo classico, proponiamo queste teorie essere duali a configurazioni di HW in cui un S-fold convive con O-piani. In tutti i casi descritti, verifichiamo la consistenza delle nostre proposte con mirror symmetry, calcolando la serie di Hilbert dei moduli space. Nel caso di G non-abeliano e livelli di CS accesi, non siamo in grado di fornire un’unica prescrizione per calcolare il moduli space. Tuttavia, studiamo dettagliatamente i modelli abeliani. Poiché in questo caso T[U(1)] è una teoria quasi vuota contente solo un termine di CS misto, siamo in grado di calcolare il moduli space, provando così a dedurre il modo di contribuire alla dinamica di T[U(N)]. Infine, studiamo l’indice superconforme delle teorie con S-fold. Tale quantità è utile per due scopi. Il primo è studiare dualità tra teorie con S-fold descritte da quiver differenti. In tale contesto, l’indice rivela come gli operatori sono mappati tra loro sotto la dualità. Il secondo scopo è studiare la quantità di supersimmetria preservata da una teoria con S-fold nel IR. Il gauging delle simmetrie globali di T[U(N)] rompe la supersimmetria a N=3. Tuttavia, in molti esempi con N finito, l’indice mostra che la supersimmetria aumenta nell’infrarosso.A notable class of 3d N=4 superconformal field theories admits a string theoretic realization and can be engineered using brane configurations of D3, D5 and NS5 branes, usually called Hanany-Witten (HW) configurations. The low energy dynamics of such theories have been extensively studied in the past year: a prominent role is played by mirror symmetry, a duality between theories having the same conformal fixed point in the infrared. Mirror symmetry can be thought as inherited from string theory S-duality. As observed by Gaiotto and Witten, HW setups can be generalized by adding new objects, SL(2,Z) duality walls, also called S-folds. When passing through this interface, the system undergoes a local SL(2,Z) transformation. HW setups where an S-fold inserted also admit a holographic description in Type-IIB supergravity as recently shown by Assel and Tomasiello. From a QFT side, the insertion of an S-fold manifests itself as a T[U(N)] theory where each U(N) factor in the global symmetry U(N)xU(N) is commonly gauged, thus generating a non-trivial coupling between two vector multiplets. In this sense, T[U(N)] plays the role of unconventional matter. We refer to theories where a T[U(N)]-link (or simply T-link) has been inserted as S-fold theories: they can be thought of as a generalization of usual N=4 circular quivers. It is worth to stress that only one U(N) factor of the global symmetry is manifest in the Lagrangian description of T[U(N)], whereas the other is emergent at the infrared fixed point. In this sense, a T-link adds a non-Lagrangian ingredient and studying S-fold theories turns out to be an intriguing challenge from a quantum field theory point of view. The aim of this thesis is to gain insight about S-fold SCFTs. We mainly focus on their vacuum moduli spaces, dualities and infrared supersymmetry. We study the moduli space of S-fold SCFTs using mirror symmetry as main tool. When all Chern-Simons (CS) levels are turned off, we propose that the Higgs branch of such theories can be computed performing an hyper-Kahler quotient. Moreover, we conjecture that the Coulomb branch is the same of the Coulomb branch of an effective quiver where the T-linked gauge nodes get frozen. We name this phenomenon freezing rule and we interpret as the fact impossibility of D3 branes to move in some directions when intersecting an S-duality wall. We also generalize S-fold SCFTs to more general cases where a T[G] theory appears, with G being orthogonal, symplectic as well as exceptional groups. For G a classical group, we propose that such theories are dual to HW configurations where an S-fold coexists with orientifold planes. In all these cases, we check our proposals computing the Hilbert series associated to each moduli space and checking it against mirror symmetry. When G is non-Abelian and the CS levels are turned on, we are not able to provide a unique prescription in order to compute the moduli space in presence of a T-link. Nevertheless, we study in full details a sub-class consisting of Abelian models. Since in this case T[U(1)] is an almost empty theory with only a mixed CS term, we are able to compute the moduli space, trying to infer how a T[U(N)] theory should enter the dynamics. Finally, we study the superconformal indices of S-fold theories. Such a quantity is useful for two purposes. The first one is to study the duality between S-fold theories with different quiver descriptions. In this context the index reveals how operators get mapped to each other under the duality. The second purpose is to study the amount of supersymmetry possessed by the S-fold theory at low energies. In principle, the gauging of the global symmetries of a T[U(N)] theory generically breaks supersymmetry down to N=3. However, in many examples with finite N, the index showed that supersymmetry gets enhanced in the infrared. This is also consistent with the supergravity duals, which suggest the enhancement of supersymmetry in the large N limit.
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Malik, Zeeshan. "Towards on-line domain-independent big data learning : novel theories and applications". Thesis, University of Stirling, 2015. http://hdl.handle.net/1893/22591.
Testo completoAbstract (sommario):
Feature extraction is an extremely important pre-processing step to pattern recognition, and machine learning problems. This thesis highlights how one can best extract features from the data in an exhaustively online and purely adaptive manner. The solution to this problem is given for both labeled and unlabeled datasets, by presenting a number of novel on-line learning approaches. Specifically, the differential equation method for solving the generalized eigenvalue problem is used to derive a number of novel machine learning and feature extraction algorithms. The incremental eigen-solution method is used to derive a novel incremental extension of linear discriminant analysis (LDA). Further the proposed incremental version is combined with extreme learning machine (ELM) in which the ELM is used as a preprocessor before learning. In this first key contribution, the dynamic random expansion characteristic of ELM is combined with the proposed incremental LDA technique, and shown to offer a significant improvement in maximizing the discrimination between points in two different classes, while minimizing the distance within each class, in comparison with other standard state-of-the-art incremental and batch techniques. In the second contribution, the differential equation method for solving the generalized eigenvalue problem is used to derive a novel state-of-the-art purely incremental version of slow feature analysis (SLA) algorithm, termed the generalized eigenvalue based slow feature analysis (GENEIGSFA) technique. Further the time series expansion of echo state network (ESN) and radial basis functions (EBF) are used as a pre-processor before learning. In addition, the higher order derivatives are used as a smoothing constraint in the output signal. Finally, an online extension of the generalized eigenvalue problem, derived from James Stone’s criterion, is tested, evaluated and compared with the standard batch version of the slow feature analysis technique, to demonstrate its comparative effectiveness. In the third contribution, light-weight extensions of the statistical technique known as canonical correlation analysis (CCA) for both twinned and multiple data streams, are derived by using the same existing method of solving the generalized eigenvalue problem. Further the proposed method is enhanced by maximizing the covariance between data streams while simultaneously maximizing the rate of change of variances within each data stream. A recurrent set of connections used by ESN are used as a pre-processor between the inputs and the canonical projections in order to capture shared temporal information in two or more data streams. A solution to the problem of identifying a low dimensional manifold on a high dimensional dataspace is then presented in an incremental and adaptive manner. Finally, an online locally optimized extension of Laplacian Eigenmaps is derived termed the generalized incremental laplacian eigenmaps technique (GENILE). Apart from exploiting the benefit of the incremental nature of the proposed manifold based dimensionality reduction technique, most of the time the projections produced by this method are shown to produce a better classification accuracy in comparison with standard batch versions of these techniques - on both artificial and real datasets.
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Selander, Keith N. "A function space approach to the generalized nonlinear model with applications to frequency domain spectral estimation". Diss., This resource online, 1992. http://scholar.lib.vt.edu/theses/available/etd-06062008-172034/.
Testo completo
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Gilbert, Gregory Wallace. "The recursive value of non-utilitarian writing as applied to cognitive domain theories". CSUSB ScholarWorks, 1989. https://scholarworks.lib.csusb.edu/etd-project/551.
Testo completo
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Kyselov, Mykola. "Phenomenological theories of magnetic multilayers and related systems". Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2011. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-63594.
Testo completoAbstract (sommario):
In this thesis multidomain states in magnetically ordered systems with competing long-range and short range interactions are under consideration. In particular, in antiferromagnetically coupled multilayers with perpendicular anisotropy unusual multidomain textures can be stabilized due to a close competition between long-range demagnetization fields and short-range interlayer exchange coupling. These spatially inhomogeneous magnetic textures of regular multidomain configurations and irregular networks of topological defects as well as complex magnetization reversal processes are described in the frame of the phenomenological theory of magnetic domains. Using a modified model of stripe domains it is theoretically shown that the competition between dipolar coupling and antiferromagnetic interlayer exchange coupling causes an instability of ferromagnetically ordered multidomain states and results in three possible ground states: ferromagnetic multidomain state, antiferromagnetic homogeneous and antiferromagnetic multidomain states. The presented theory allows qualitatively to define the area of existence for each of these states depending on geometrical and material parameters of multilayers. In antiferromagnetically coupled superlattices with perpendicular anisotropy an applied magnetic bias field stabilizes specific multidomain states, so-called metamagnetic domains. A phenomenological theory developed in this thesis allows to derive the equilibrium sizes of metamagnetic stripe and bubble domains as functions of the antiferromagnetic exchange, the magnetic bias field, and the geometrical parameters of the multilayer. The magnetic phase diagram includes three different types of metamagnetic domain states,
namely multidomains in the surface layer and in internal layers, and also mixed multidomain states may arise. Qualitative and quantitative analysis of step-like magnetization reversal shows a good agreement between the theory and experiment. Analytical equations have been derived for the stray field components of these multidomain states in perpendicular multilayer systems. In particular, closed expressions for stray fields in the case of ferromagnetic and antiferromagnetic stripes are presented. The theoretical approach provides a basis for the analysis of magnetic force microscopy (MFM) images from this class of nanomagnetic systems. Peculiarities of the MFM contrast have been calculated for realistic tip models. These characteristic features in the MFM signals can be employed for the investigations of the different multidomain modes. The methods developed for stripe-like magnetic domains are employed to calculate magnetization processes in twinned microstructures of ferromagnetic shape-memory materials. The remarkable phenomenon of giant magnetic field induced strain transformations in such ferromagnetic shape memory alloys as Ni-Mn-Ga, Ni-Mn-Al, or Fe-Pd arises as an interplay of two physical effects: (i) A martensitic transition creating competing phases, i.e. crystallographic
domains or variants, which are crystallographically equivalent but have different orientation. (ii) High uniaxial magnetocrystalline anisotropy that pins the magnetization vectors along certain directions of these martensite variants. Then, an applied magnetic field can drive a microstructural transformation by which the martensitic twins, i.e. the different crystallographic domains, are redistributed in the martensitic state. Within the phenomenological (micromagnetic) theory the equilibrium parameters of multivariant stripe patterns have been derived as functions of the applied field for an extended single-crystalline plate. The calculated magnetic phase diagram allows to give a detailed description of the magnetic field-driven martensitic twin rearrangement in single crystals of magnetic shape-memory alloys. The analysis reveals the crucial role of preformed twins and of the dipolar stray-field energy for the magnetic-field driven transformation process in magnetic shape-memory materials. This work has been done in close collaboration with a group of experimentalists from Institute of Metallic Materials of IFW Dresden, Germany and San Jose Research Center of
Hitachi Global Storage Technologies, United States. Comparisons between theoretical and experimental data from this cooperation are presented throughout this thesis as vital part of my work on these different subjects.
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Varzinczak, Ivan. "What Is a Good Domain Description? Evaluating & Revising Action Theories in Dynamic Logic". Phd thesis, Université Paul Sabatier - Toulouse III, 2006. http://tel.archives-ouvertes.fr/tel-00319220.
Testo completoAbstract (sommario):
Traditionally, consistency is the only criterion for the quality of a theory in logic-based approaches to reasoning about actions. This work goes beyond that and contributes to the meta-theory of actions by investigating what other properties a good domain description should satisfy. Having Propositional Dynamic Logic (PDL) as background, we state some meta-theoretical postulates concerning this sore spot. When all postulates are satisfied, we call the action theory modular. We point out the problems that arise when the postulates about modularity are violated, and propose algorithmic checks that can help the designer of an action theory to overcome them. Besides being easier to understand and more elaboration tolerant in McCarthy's sense, modular theories
have interesting computational properties. Moreover, we also propose a framework for updating domain descriptions and show the importance modularity has in action theory change.
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Sessa, Mirko. "An SMT-based framework for the formal analysis of Switched Multi-Domain Kirchhoff Networks". Doctoral thesis, Università degli studi di Trento, 2019. http://hdl.handle.net/11572/243432.
Testo completoAbstract (sommario):
Many critical systems are based on the combination of components from different physical domains (e.g. mechanical, electrical, hydraulic), and are mathematically modeled as Switched Multi-Domain Kirchhoff Networks (SMDKN).
In this thesis, we tackle a major obstacle to formal verification of SMDKN, namely devising a global model amenable to verification in the form of a Hybrid Automaton. This requires the combination of the local dynamics of the components, expressed as Differential Algebraic Equations, according to Kirchhoff's laws, depending on the (exponentially many) operation modes of the network.
We propose an automated SMT-based method to analyze networks from multiple physical domains, detecting which modes induce invalid (i.e. inconsistent) constraints, and to produce a Hybrid Automaton model that accurately describes, in terms of Ordinary Differential Equations, the system evolution in the valid modes, catching also the possible non-deterministic behaviors.
The experimental evaluation demonstrates that the proposed approach allows several complex multi-domain systems to be formally analyzed and model checked against various system requirements.
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Sessa, Mirko. "An SMT-based framework for the formal analysis of Switched Multi-Domain Kirchhoff Networks". Doctoral thesis, Università degli studi di Trento, 2019. http://hdl.handle.net/11572/243432.
Testo completoAbstract (sommario):
Many critical systems are based on the combination of components from different physical domains (e.g. mechanical, electrical, hydraulic), and are mathematically modeled as Switched Multi-Domain Kirchhoff Networks (SMDKN).
In this thesis, we tackle a major obstacle to formal verification of SMDKN, namely devising a global model amenable to verification in the form of a Hybrid Automaton. This requires the combination of the local dynamics of the components, expressed as Differential Algebraic Equations, according to Kirchhoff's laws, depending on the (exponentially many) operation modes of the network.
We propose an automated SMT-based method to analyze networks from multiple physical domains, detecting which modes induce invalid (i.e. inconsistent) constraints, and to produce a Hybrid Automaton model that accurately describes, in terms of Ordinary Differential Equations, the system evolution in the valid modes, catching also the possible non-deterministic behaviors.
The experimental evaluation demonstrates that the proposed approach allows several complex multi-domain systems to be formally analyzed and model checked against various system requirements.
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Gao, Yang Verfasser], Martin [Akademischer Betreuer] [Fränzle e Paolo [Akademischer Betreuer] Zuliani. "Verification of Stochastic Systems by Stochastic Satisfiability Modulo Theories with Continuous Domain (CSSMT) / Yang Gao ; Martin Fränzle, Paolo Zuliani". Oldenburg : BIS der Universität Oldenburg, 2017. http://d-nb.info/1147559287/34.
Testo completo
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Gao, Yang [Verfasser], Martin [Akademischer Betreuer] Fränzle e Paolo [Akademischer Betreuer] Zuliani. "Verification of Stochastic Systems by Stochastic Satisfiability Modulo Theories with Continuous Domain (CSSMT) / Yang Gao ; Martin Fränzle, Paolo Zuliani". Oldenburg : BIS der Universität Oldenburg, 2017. http://d-nb.info/1147559287/34.
Testo completo
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Ravyse, Natasha Elfbiede. "Against all odds : the status of Fanagalo in South Africa today / N.E. Ravyse". Thesis, North-West University, 2013. http://hdl.handle.net/10394/10604.
Testo completoAbstract (sommario):
Sub-cultural languages in South Africa – languages which do not enjoy official status amongst other qualities – have not received much attention academically. Existing theories of maintenance and shift accommodate mainstream languages in their role and function within dominant society. However the sub-cultural languages, in which Fanagalo will later be categorised, and their role and function in society are unclear. This may be the result of the inefficiency of current theories of maintenance and shift to explain the functionality of sub-cultural languages and the process they undergo leading to either maintenance or shift. Furthermore, failure to recognise the role and function of such sub-cultural languages may be attributed to their non-official status as they are not officially supported by language policies. The purpose of this study is therefore to understand the process of maintenance or shift a sub-cultural language undergoes. This process is accommodated by developing a theoretical model related to maintenance or shift for sub-cultural languages. This model, specifically based on Fanagalo, will expand on the boundaries set in existing theoretical models of maintenance and shift in order to accommodate sub-cultural language. It is important to stress that the period during which the data was collected on site at Mine X in Rustenburg, is volatile in nature. The unrest in the social context concerning the mine workers themselves during the period in which this data was gathered alludes to the value of the data and provides a unique insight not achievable under non-adverse circumstances. The unrest began in 2012 during which a “strike over pay ha(d) escalated into alleged turf war between unions” (Smith & Macalister, 2012) in Marikana, Rustenburg where more than thirty people were killed on the 17th of August, 2012. A year later, an agreement between Amcu (Association of Mineworkers and Construction Union) and Lonmin was signed which, according to Mathunjwa, president of Amcu, was quoted as saying, ‘This shows that the victims did not die in vain and we pledge to continue with their fight for a living wage” (Mathunjwa, 2013, quoted by Steyn, 2013). This pledge was upheld as on 28 August, 2013, Amcu was, “asking for increases as high as 150%, and Solidarity are still engaging” (Nicolson, 2013). As the interviews as part of the data collection process for this study were conducted on 14 August 2013, the value of the data should not go unrecognised.MA (English), North-West University, Vaal Triangle Campus, 2014
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Riviere, Peter. "Génération automatique d’obligations de preuves paramétrée par des théories de domaine dans Event-B : Le cadre de travail EB4EB". Electronic Thesis or Diss., Université de Toulouse (2023-....), 2024. http://www.theses.fr/2024TLSEP052.
Testo completoAbstract (sommario):
De nos jours, nous sommes entourés de systèmes critiques complexes tels que les microprocesseurs, les trains, les appareils intelligents, les robots, les avions, etc. Ces systèmes sont extrêmement complexes et critiques en termes de sûreté, et doivent donc être vérifiés et validés. L'utilisation de méthodes formelles à états s'est avérée efficace pour concevoir des systèmes complexes. Event-B a joué un rôle clé dans le développement de tels systèmes. Event-B est une méthode formelle de conception de systèmes à états avec une approche correcte par construction, qui met l'accent sur la preuve et le raffinement. Event-B facilite la vérification de propriétés telles que la préservation des invariants, la convergence et le raffinement en générant des obligations de preuve et en permettant de les décharger.Certaines propriétés additionnelles du système, telles que l'absence d'inter-blocage, l'atteignabilité ou encore la vivacité, doivent être explicitement encodées et vérifiées par le concepteur, ou formalisées à l'aide d'une autre méthode formelle. Une telle approche pénalise la réutilisabilité des modèles et des techniques, et peut introduire des erreurs, en particulier dans les systèmes complexes.Pour pallier cela, nous avons introduit un "framework" réflexif EB4EB, formalisé au sein de Event-B. Dans ce cadre, chacun des concepts d'Event-B est formalisé comme un objet de première classe en utilisant la logique du premier ordre (FOL) et la théorie des ensembles. EB4EB permet la manipulation et l'analyse de modèles Event-B, et permet la définition d'extensions afin de réaliser des analyses supplémentaires non intrusives sur des modèles, telles que la validation de propriétés temporelles, l'analyse de la couverture d'un invariant, ou encore l'absence de blocage. Ce framework est réalisé grâce aux théories d'Event-B, qui étendent le langage d'Event-B avec des éléments définis dans des théories, et aussi en formalisant de nouvelles obligations de preuves, qui ne sont pas présentes initialement dans Event-B.De plus, la sémantique opérationnelle d'Event-B (basée sur les traces) a été formalisée, de même qu'un cadre qui sert à garantir la correction des théorèmes définis, y compris les opérateurs et les obligations de preuve. Enfin, le cadre proposé et ses extensions ont été validés dans de multiples études de cas, notamment l'horloge de Lamport, le problème du lecteur/rédacteur, l'algorithme de Peterson, les distributeurs automatiques de billets (DAB), les véhicules autonomes, etcNowadays, we are surrounded by complex critical systems such as microprocessors, railways, home appliances, robots, aeroplanes, and so on. These systems are extremely complex and are safety-critical, and they must be verified and validated. The use of state-based formal methods has proven to be effective in designing complex systems. Event-B has played a key role in the development of such systems. Event-B is a formal system design method that is state-based and correct-by-construction, with a focus on proof and refinement. Event-B facilitates verification of properties such as invariant preservation, convergence, and refinement by generating and discharging proof obligations.Additional properties for system verification, such as deadlock-freeness, reachability, and liveness, must be explicitly defined and verified by the designer or formalised using another formal method. Such an approach reduces re-usability and may introduce errors, particularly in complex systems.To tackle these challenges, we introduced the reflexive EB4EB framework in Event-B. In this framework, each Event-B concept is formalised as a first-class object using First Order Logic (FOL) and set theory. This framework allows for the manipulation and analysis of Event-B models, with extensions for additional, non-intrusive analyses such as temporal properties, weak invariants, deadlock freeness, and so on. This is accomplished through Event-B Theories, which extend the Event-B language with the theory's defined elements, and also by formalising and articulating new proof obligations that are not present in traditional Event-B. Furthermore, Event-B's operational semantics (based on traces) have been formalised, along with a framework for guaranteeing the soundness of the defined theorems, including operators and proof obligations. Finally, the proposed framework and its extensions have been validated across multiple case studies, including Lamport's clock case study, read/write processes, the Peterson algorithm, Automated Teller Machine (ATM), autonomous vehicles, and so on
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Davies, Brian E., Graham M. L. Gladwell, Josef Leydold e Peter F. Stadler. "Discrete Nodal Domain Theorems". Department of Statistics and Mathematics, Abt. f. Angewandte Statistik u. Datenverarbeitung, WU Vienna University of Economics and Business, 2000. http://epub.wu.ac.at/976/1/document.pdf.
Testo completo
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Davies, Brian E., Josef Leydold e Peter F. Stadler. "Discrete Nodal Domain Theorems". Department of Statistics and Mathematics, Abt. f. Angewandte Statistik u. Datenverarbeitung, WU Vienna University of Economics and Business, 2000. http://epub.wu.ac.at/1674/1/document.pdf.
Testo completo
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Biyikoglu, Türker, Josef Leydold e Peter F. Stadler. "Nodal Domain Theorems and Bipartite Subgraphs". Department of Statistics and Mathematics, Abt. f. Angewandte Statistik u. Datenverarbeitung, WU Vienna University of Economics and Business, 2005. http://epub.wu.ac.at/626/1/document.pdf.
Testo completoAbstract (sommario):
The Discrete Nodal Domain Theorem states that an eigenfunction of the k-th largest eigenvalue of a generalized graph Laplacian has at most k (weak) nodal domains. We show that the number of strong nodal domains cannot exceed the size of a maximal induced bipartite subgraph and that this bound is sharp for generalized graph Laplacians. Similarly, the number of weak nodal domains is bounded by the size of a maximal bipartite minor. (author's abstract)Series: Preprint Series / Department of Applied Statistics and Data Processing
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Revenko, Artem. "Automatic Construction of Implicative Theories for Mathematical Domains". Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-197794.
Testo completoAbstract (sommario):
Implication is a logical connective corresponding to the rule of causality "if ... then ...". Implications allow one to organize knowledge of some field of application in an intuitive and convenient manner. This thesis explores possibilities of automatic construction of all valid implications (implicative theory) in a given field. As the main method for constructing implicative theories a robust active learning technique called Attribute Exploration was used. Attribute Exploration extracts knowledge from existing data and offers a possibility of refining this knowledge via providing counter-examples. In frames of the project implicative theories were constructed automatically for two mathematical domains: algebraic identities and parametrically expressible functions. This goal was achieved thanks both pragmatical approach of Attribute Exploration and discoveries in respective fields of application. The two diverse application fields favourably illustrate different possible usage patterns of Attribute Exploration for automatic construction of implicative theories.
19
Rinaldi, Davide. "Formal methods in the theories of rings and domains". Diss., Ludwig-Maximilians-Universität München, 2014. http://nbn-resolving.de/urn:nbn:de:bvb:19-175705.
Testo completoAbstract (sommario):
In recent years, Hilbert's Programme has been resumed within the framework of constructive mathematics. This undertaking has already shown its feasability for a considerable part of commutative algebra. In particular, point-free methods have been playing a primary role, emerging as the appropriate language for expressing the interplay between real and ideal in mathematics.
This dissertation is written within this tradition and has Sambin's notion of formal topology at its core. We start by developing general tools, in order to make this notion more immediate for algebraic application. We revise the Zariski spectrum as an inductively generated basic topology, and we analyse the constructive status of the corresponding principles of spatiality and reducibility. Through a series of examples, we show how the principle of spatiality is recurrent in the mathematical practice.
The tools developed before are applied to specific problems in constructive algebra. In particular, we find an elementary characterization of the notion of codimension for ideals of a commutative ring, by means of which a constructive version of Krull's principal ideal theorem can be stated and proved. We prove a formal version of the projective Eisenbud-Evans-Storch theorem. Finally, guided by the algebraic intuition, we present an application in constructive domain theory, by proving a finite version of Kleene-Kreisel density theorem for non-flat information systems.In den vergangenen Jahren wurde das Hilbertsche Programm im Rahmen der konstruktiven Mathematik wiederaufgenommen. Diese Unternehmung hat sich vor allem in der kommutativen Algebra als praktikabel erwiesen. Insbesondere spielen punktfreie Methoden eine wesentliche Rolle: sie haben sich als die angemessene Sprache herausgestellt, um das Zwischenspiel von "real'" und "ideal" in der Mathematik auszudrücken. Die vorliegende Dissertation steht in dieser Tradition; zentral ist Sambins Begriff der formalen Topologie. Zunächst entwickeln wir ein allgemeines Instrumentarium, das geeignet ist, diesen Begriff seinen algebraischen Anwendungen näherzubringen. Sodann arbeiten wir das Zariski-Spektrum in eine induktiv erzeugte "basic topology" um und analysieren den konstruktiven Status der einschlägigen Varianten von Spatialität und Reduzibilität. Durch Angabe einer Reihe von Instanzen zeigen wir, wie häufig das Prinzip der Spatialität in der mathematischen Praxis vorkommt. Die eigens entwickelten Werkzeuge werden schließlich auf spezifische Probleme aus der konstruktiven Algebra angewandt. Insbesondere geben wir eine elementare Charakterisierung der Kodimension eines Ideals in einem kommutativen Ring an, mit der eine konstruktive Fassung des Krullschen Hauptidealsatzes formuliert und bewiesen werden kann. Ferner beweisen wir eine formale Fassung des Satzes von Eisenbud-Evans-Storch im projektiven Fall. Geleitet von der algebraischen Intuition stellen wir zuletzt eine Anwendung in der konstruktiven Bereichstheorie vor, indem wir eine finite Variante des Dichtheitssatzes von Kleene und Kreisel für nicht-flache Informationssysteme beweisen.
20
Biyikoglu, Türker. "A Discrete Nodal Domain Theorem for Trees". Department of Statistics and Mathematics, Abt. f. Angewandte Statistik u. Datenverarbeitung, WU Vienna University of Economics and Business, 2002. http://epub.wu.ac.at/1270/1/document.pdf.
Testo completoAbstract (sommario):
Let G be a connected graph with n vertices and let x=(x1, ..., xn) be a real vector. A positive (negative) sign graph of the vector x is a maximal connected subgraph of G on vertices xi>0 (xi<0). For an eigenvalue of a generalized Laplacian of a tree: We characterize the maximal number of sign graphs of an eigenvector. We give an O(n2) time algorithm to find an eigenvector with maximum number of sign graphs and we show that finding an eigenvector with minimum number of sign graphs is an NP-complete problem. (author's abstract)Series: Preprint Series / Department of Applied Statistics and Data Processing
21
Fulcrand, Julien. "Les changements en chaîne historiques confrontés à la phonologie moderne : Propulsion et traction modélisées par deux approches de préservation". Thesis, Lille 3, 2017. http://www.theses.fr/2017LIL30023/document.
Testo completoAbstract (sommario):
L'objectif de cette thèse est de modéliser les changements en chaîne historiques dans les théories phonologiques modernes. Martinet (1952, 1955, 1970) distingue deux principales catégories de changements en chaîne: les chaînes de propulsion et les chaînes de traction. Les chaînes de propulsion seront traitées dans la première partie de cette thèse (chapitres 2 et 3). Afin de modéliser les chaînes de propulsion, un modèle existant est utilisé: La théorie de préservation du contraste de Łubowicz (2003, 2012). Concernant la modélisation des chaînes de traction, qui sera principalement traitée dans la seconde partie de le thèse (chapitres 4 et 5), une nouvelle théorie sera proposée, basée sur les travaux phonétiques de De Boer (2001). Cette proposition est basée sur la notion des domaines piliers. Le chapitre 1 s'ouvre sur l'observation que ni les théories dérivationnelles orientées vers l'input – type SPE – ni les théories orientées vers l'output, comme la théorie de l'optimalité de Prince & Smolensky (TO) sont en mesure de formaliser les changements en chaîne. Dans les théories dérivationnelles, il est possible d'obtenir une bonne description des changements en chaîne. Cependant, afin de faire cela, nous devons briser les liens unissant les différentes étapes des changements en chaîne. Par conséquent, nous perdons l'interdépendance systémique entre les stades, ce qui est au cœur des changements en chaîne. Concernant la théorie de l'optimalité, sa structure stricte sur deux niveaux se révèle problématique dans le cas des changements en chaîne. Dans un changement en chaîne schématique comme /a/ → [e] > /e/ → [i], il est impossible pour la TO, dans la même analyse, de faire en sorte que [e] soit un candidat optimal et /e/ un candidat bloqué. Dans le chapitre 2, nous analysons et comparons plusieurs amendements à la théorie de l'optimalité proposés pour rendre compte des changements en chaîne. Beaucoup d'entre eux ne sont pas satisfaisants dans le cas des changements en chaîne car ils ne parviennent pas à modéliser la force systémique des changements en chaîne. La seule théorie qui semble accomplir cet objectif est la théorie de préservation du contraste (CPT) de Łubowicz. Cette théorie est basée sur les notions de contraste, préservation du contraste et elle évalue des scénarios au lieu de candidats individuels. La préservation du contraste est accomplie à travers la transformation du contraste. La notion de transformation du contraste signifie que les niveaux de contraste du système pré-changement sont préservés dans le système post-changement mais leur nature change. Une observation sur la CPT est que Łubowicz l'avait originellement conçue pour les changements en chaîne synchroniques. Dans le chapitre 2, nous démontrons que la CPT est en mesure de modéliser la force systémique qui donne aux changements en chaîne diachroniques leur cohérence. Ainsi, dans le chapitre 3, nous décidons de tester la validité de la CPT sur de véritables changements en chaîne historiques. Nous avançons deux études de cas sur deux changements en chaîne. Le premier, bien connu, est le changement en chaîne vocalique du Grand Changement Vocalique Anglais (English Great Vowel Shift). L'autre changement en chaîne est la Seconde Mutation Consonantique allemande (High German Consonant Shift). Nous démontrons que la CPT est en mesure de rendre compte de ces deux changements en chaîne. Au terme du chapitre 3, la CPT est testée sur une autre catégorie de changements en chaîne : les changements en chaîne observés dans l'acquisition de la langue maternelle. Le changement en chaîne étudié est s → θ → f. Ce changement en chaîne est différent des deux autres car il n'y a pas de nouveau niveau de contraste créé. Le dernier stade du changement en chaîne se conclut par une fusion. Encore une fois, la CPT peut rendre compte de ce changement en chaîne de manière satisfaisanteThe aim of this thesis is to formalise historical chain shifts within modern phonological theories. Martinet (1952, 1955, 1970) distinguishes two main categories of chain shifts: push chains and pull chains. Push chains will be dealt with in the first main part of this thesis (chapters 2 and 3). For modelling of push chains, an existing model is used: Łubowicz's (2003, 2012) Contrast Preservation Theory. For modelling pull chains, which will be the focus of the second part of this thesis (chapters 4 and 5), a new theory will be proposed, based on the phonetic work by De Boer (2001). This proposition is based on the notion of the pillar domains (domaines piliers). Chapter 1 starts with the observation that neither the derivational, SPE-like, theories or output driven theories like Prince's & Smolensky's Optimality Theory (OT) are able to formalise chain shifts properly. Within the derivational theories, it is possible to get a correct description of a chain shift. However, in order to do that, we have to break the links between the different stages of the chain shift. Therefore, one loses the systemic interdependence of the different stages, which is the essence of the chain shift. As regards to Optimality Theory, it is the two-level structure of the theory which proves problematic for chain shifts. In a theoretical chain shift such as /a/ → [e] > /e/ → [i], it is impossible for OT to make, in the same analysis, [e] an optimal candidate and /e/ a non-optimal one. In chapter 2, we analyse and compare several output-driven propositions that have been made to account for chain shifts. Many of them are not satisfactory because they do not manage to model the systemic motivation of chain shifts. The only theory that seems able to complete this objective is Łubowicz's Contrast Preservation Theory (CPT). This theory is based on the notions of contrast, contrast preservation and it evaluates scenarios rather than individual candidates. Contrast preservation is achieved through contrast transformation. The term contrast transformation indicates that the contrast levels of the input system are preserved but that their nature is different in the output system. One observation about CPT is that Łubowicz designed it for synchronic chain shifts. In chapter 2, we prove that CPT is able to model the perceptible coherence in diachronic chain shifts. In chapter 3, thus we decide to test the validity of CPT on actual historical chain shifts. It is tested on two cases. One is the well-known vocalic chain shift the Great Vowel Shift in English. The other one is the Second German Sound Shift (or High German Consonant Shift). We demonstrate that CPT is able to account for both of these chain shifts. At the end of chapter 3, CPT is tested on another type of chain shifts, i.e. chain shifts in first-language acquisition. The studied chain shift is s → θ → f. This chain shift is different from the other two because there is no new contrast level created. The last stage of this chain shift ends with a merger . Once again, CPT can account for this chain shift in a coherent way
22
Gibson, Iain R. "Decomposition theorems for quasi-discrete planar domains". Thesis, University of Edinburgh, 2003. http://hdl.handle.net/1842/14905.
Testo completo
23
Elzaidi, Salaeddin Mohamad. "Some theorems concerning linear differential equations in the complex domain". Thesis, University of Nottingham, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.320786.
Testo completo
24
Winterstein, Daniel. "Using diagrammatic reasoning for theorem proving in a continuous domain". Thesis, University of Edinburgh, 2005. http://hdl.handle.net/1842/642.
Testo completoAbstract (sommario):
This project looks at using diagrammatic reasoning to prove mathematical theorems. The work is motivated by a need for theorem provers whose reasoning is readily intelligible to human beings. It should also have practical applications in mathematics teaching. We focus on the continuous domain of analysis - a geometric subject, but one which is taught using a dry algebraic formalism which many students find hard. The geometric nature of the domain makes it suitable for a diagram-based approach. However it is a difficult domain, and there are several problems, including handling alternating quantifiers, sequences and generalisation. We developed representations and reasoning methods to solve these. Our diagram logic isn't complete, but does cover a reasonable range of theorems. It utilises computers to extend diagrammatic reasoning in new directions – including using animation. This work is tested for soundness, and evaluated empirically for ease of use. We demonstrate that computerised diagrammatic theorem proving is not only possible in the domain of real analysis, but that students perform better using it than with an equivalent algebraic computer system.
25
Fusacchia, Gabriele. "Injective modules over semistar Noetherian domains". Doctoral thesis, Università degli studi di Padova, 2011. http://hdl.handle.net/11577/3427410.
Testo completoAbstract (sommario):
We approach the problem of classifying injective modules over an integral domain by using the tool of semistar operations. In light of the classical results obtained by Matlis in the case of Noetherian rings, we first study the structure of the so called semistar Noetherian domains, then we discuss how every semistar operation over a semistar Noetherian domain determines a special subclass of the injective modules which can be successfully classified in terms of cardinal invariants.Questo lavoro affronta il problema della classificazione dei moduli iniettivi su di un dominio integro, usando lo strumento delle operazioni semistar. Prendendo spunto dai risultati classici di Matlis per il caso Noetheriano, viene prima studiata la struttura dei cosiddetti domini semistar Noetheriani, quindi viene mostrato come ogni operazione semistar su un tale dominio determini una sottoclasse speciale dei moduli iniettivi che può essere classificata in termini di invarianti cardinali.
26
Rinaldi, Davide [Verfasser], e Peter [Akademischer Betreuer] Schuster. "Formal methods in the theories of rings and domains / Davide Rinaldi. Betreuer: Peter Schuster". München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2014. http://d-nb.info/1062492641/34.
Testo completo
27
Kara, F. "The domain hydrodynamic and hydroelastic analysis of floating bodies with forward speed". Thesis, University of Strathclyde, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.366659.
Testo completo
28
Gonzalez, Espinoza Luis. "The Knaster-Kuratowski-Mazurkiewicz theorem and abstract convexities". Diss., Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/28640.
Testo completo
29
Dinnie, Keith. "Conceptualising nation branding : a qualitative inquiry into an under-theorised domain in marketing". Thesis, Glasgow Caledonian University, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.422048.
Testo completo
30
Bartolini, Gabriel. "On Poicarés Uniformization Theorem". Thesis, Linköping University, Department of Mathematics, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-7968.
Testo completoAbstract (sommario):
A compact Riemann surface can be realized as a quotient space $\mathcal{U}/\Gamma$, where $\mathcal{U}$ is the sphere $\Sigma$, the euclidian plane $\mathbb{C}$ or the hyperbolic plane $\mathcal{H}$ and $\Gamma$ is a discrete group of automorphisms. This induces a covering $p:\mathcal{U}\rightarrow\mathcal{U}/\Gamma$.
For each $\Gamma$ acting on $\mathcal{H}$ we have a polygon $P$ such that $\mathcal{H}$ is tesselated by $P$ under the actions of the elements of $\Gamma$. On the other hand if $P$ is a hyperbolic polygon with a side pairing satisfying certain conditions, then the group $\Gamma$ generated by the side pairing is discrete and $P$ tesselates $\mathcal{H}$ under $\Gamma$.
31
Backhouse, Kevin Stuart. "Abstract interpretation of domain-specific embedded languages". Thesis, University of Oxford, 2002. http://ora.ox.ac.uk/objects/uuid:9138936a-145a-4e0e-9a59-f432f8c4e9d0.
Testo completoAbstract (sommario):
A domain-specific embedded language (DSEL) is a domain-specific programming language with no concrete syntax of its own. Defined as a set of combinators encapsulated in a module, it borrows the syntax and tools (such as type-checkers and compilers) of its host language; hence it is economical to design, introduce, and maintain. Unfortunately, this economy is counterbalanced by a lack of room for growth. DSELs cannot match sophisticated domain-specific languages that offer tools for domainspecific error-checking and optimisation. These tools are usually based on syntactic analyses, so they do not work on DSELs. Abstract interpretation is a technique ideally suited to the analysis of DSELs, due to its semantic, rather than syntactic, approach. It is based upon the observation that analysing a program is equivalent to evaluating it over an abstract semantic domain. The mathematical properties of the abstract domain are such that evaluation reduces to solving a mutually recursive set of equations. This dissertation shows how abstract interpretation can be applied to a DSEL by replacing it with an abstract implementation of the same interface; evaluating a program with the abstract implementation yields an analysis result, rather than an executable. The abstract interpretation of DSELs provides a foundation upon which to build sophisticated error-checking and optimisation tools. This is illustrated with three examples: an alphabet analyser for CSP, an ambiguity test for parser combinators, and a definedness test for attribute grammars. Of these, the ambiguity test for parser combinators is probably the most important example, due to the prominence of parser combinators and their rather conspicuous lack of support for the well-known LL(k) test. In this dissertation, DSELs and their signatures are encoded using the polymorphic lambda calculus. This allows the correctness of the abstract interpretation of DSELs to be proved using the parametricity theorem: safety is derived for free from the polymorphic type of a program. Crucially, parametricity also solves a problem commonly encountered by other analysis methods: it ensures the correctness of the approach in the presence of higher-order functions.
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JUVANON, DU VACHAT REGIS. "Initialisation intrinseque par modes normaux. Theorie et application a un modele a domaine limite". Paris 6, 1989. http://www.theses.fr/1989PA066691.
Testo completoAbstract (sommario):
Un schema d'initialistion qui ne necessite pas le calcul explicite des modes normaux des equations linearisees a ete formule. Un tel schema est interessant pour les modeles a domaine limite pour lesquels les modes normaux ne peuvent etre aisement calcules du fait de leur non separabilite. Des experiences variees ont ete realisees avec des modeles barotropes a domaine limite, demontrant l'efficacite d'un tel schema pour filtrer les ondes de gravite durant les simulations
33
Revenko, Artem [Verfasser], Bernhard [Akademischer Betreuer] Ganter, Gernot [Akademischer Betreuer] Salzer e Sebastian [Gutachter] Rudolph. "Automatic Construction of Implicative Theories for Mathematical Domains / Artem Revenko ; Gutachter: Sebastian Rudolph ; Bernhard Ganter, Gernot Salzer". Dresden : Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2016. http://d-nb.info/111406761X/34.
Testo completo
34
Revenko, Artem Verfasser], Bernhard [Akademischer Betreuer] Ganter, Gernot [Akademischer Betreuer] [Salzer e Sebastian [Gutachter] Rudolph. "Automatic Construction of Implicative Theories for Mathematical Domains / Artem Revenko ; Gutachter: Sebastian Rudolph ; Bernhard Ganter, Gernot Salzer". Dresden : Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2016. http://d-nb.info/111406761X/34.
Testo completo
35
Azizoglu, Suha Alp. "Time Domain Scattering From Single And Multiple Objects". Phd thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/12609413/index.pdf.
Testo completoAbstract (sommario):
The importance of the T-matrix method is well-known when frequency domain scattering problems are of interest. With the relatively recent and wide-spread interest in time domain scattering problems, similar applications of the T-matrix method are expected to be useful in the time domain. In this thesis, the time domain spherical scalar wave functions are introduced, translational addition theorems for the time domain spherical scalar wave functions necessary for the solution of multiple scattering problems are given, and the formulation of time domain scattering of scalar waves by two spheres and by two scatterers of arbitrary shape is presented. The whole analysis is performed in the time domain requiring no inverse Fourier integrals to be evaluated. Scattering examples are studied in order to check the numerical accuracy, and demonstrate the utility of the expressions.
36
Nédellec, Claire. "Apt, apprentissage interactif de regles de resolution de problemes en presence de theorie du domaine". Paris 11, 1994. http://www.theses.fr/1994PA112045.
Testo completoAbstract (sommario):
Cette these propose au travers du systeme apprenti apt (apprentice tool) un cycle complet d'apprentissage interactif de regles de resolution de probleme. Apt fonctionne selon deux modes, un mode de resolution et un mode d'acquisition de connaissances par apprentissage automatique destine a ameliorer la resolution. L'apprentissage lui-meme s'organise en cinq phases qui sont: l'acquisition d'un exemple initial de regle de resolution de probleme aupres d'un expert, la completion de l'exemple et de la theorie du domaine en vue de l'apprentissage, la generalisation incrementale de l'exemple complete basee sur des exemples generes automatiquement, la validation de la definition de concept apprise et, si necessaire, la revision de la definition apprise et de la theorie. Pour chacune de ces etapes nous presentons une methode originale d'apprentissage qui prend en charge une partie de la tache de modelisation des connaissances laissee habituellement a la charge de l'utilisateur. Les connaissances ainsi modelisees sont les exemples et la theorie du domaine necessaires a l'apprentissage. Les algorithmes d'apprentissage de apt sont decrits, d'une part, en utilisant le formalisme des reseaux semantique et d'autre part, dans un sous-ensemble de la logique d'ordre un qui nous permet de presenter une comparaison detaillee avec d'autres methodes d'apprentissage. Un exemple d'application de apt comme outil d'acquisition des connaissances pour l'attribution de prets bancaires est egalement detaille
37
Huffman, Brian Charles. "HOLCF '11: A Definitional Domain Theory for Verifying Functional Programs". PDXScholar, 2011. https://pdxscholar.library.pdx.edu/open_access_etds/113.
Testo completoAbstract (sommario):
HOLCF is an interactive theorem proving system that uses the mathematics of domain theory to reason about programs written in functional programming languages. This thesis introduces HOLCF '11, a thoroughly revised and extended version of HOLCF that advances the state of the art in program verification: HOLCF '11 can reason about many program definitions that are beyond the scope of other formal proof tools, while providing a high degree of proof automation. The soundness of the system is ensured by adhering to a definitional approach: New constants and types are defined in terms of previous concepts, without introducing new axioms. Major features of HOLCF '11 include two high-level definition packages: the Fixrec package for defining recursive functions, and the Domain package for defining recursive datatypes. Each of these uses the domain-theoretic concept of least fixed points to translate user-supplied recursive specifications into safe low-level definitions. Together, these tools make it easy for users to translate a wide variety of functional programs into the formalism of HOLCF. Theorems generated by the tools also make it easy for users to reason about their programs, with a very high level of confidence in the soundness of the results. As a case study, we present a fully mechanized verification of a model of concurrency based on powerdomains. The formalization depends on many features unique to HOLCF '11, and is the first verification of such a model in a formal proof tool.
38
Ciraud-Lanoue, Perrine. "Prépositions, préverbes et postverbes en anglais et en français. Le cas de away, off et out. Approche syntaxique et sémantique". Thesis, Poitiers, 2013. http://www.theses.fr/2013POIT5019/document.
Testo completoAbstract (sommario):
Dressant le constat que le traitement classique des différentes valeurs des particules et verbes à particule en termes de métaphore spatio-temporelle et de degré d'idiomaticité ne fait qu'entretenir l'impression que le "sens" de ces verbes composés est une donnée fondamentalement imprévisible et aléatoire, ce travail s'efforce de montrer qu'il est, au contraire, possible de rendre compte de la complexité des phénomènes mis en jeu par ceux-ci tout en en soulignant les régularités. A travers l'exemple du triplet de marqueurs away, off, et out, démonstration est faite qu'à l'issue d'un examen systématique des valeurs d'une particule donnée, et en recourant aux outils développés dans le cadre de la Théorie des Opérations Enonciatives, une forme schématique stable, définie à partir d'opérations de repérage abstrait, peut être dégagée, qui permet de placer tous ses emplois sur un même plan, comme produits de la variation en co-texte de ladite forme schématique. On est alors en mesure de s'intéresser à certains des ressorts de l'interaction entre verbe et particule à la faveur d'une étude de casWhen traditional analyses of particles and phrasal verbs in terms of space and time metaphor and degree of idiomaticity only reinforce the impression that their meanings are of a fundamentally random and unpredictable nature, this work tries to prove that it is in fact possible to account for the complexity and diversity of phenomena involved by phrasal verbs while emphasizing how constant and consistent their behaviour is. Via the example of the three markers away, off and out, it is shown that, following a thorough examination of the values of a given particle, and using the conceptual tools developed within the framework provided by the Theory of Enunciative Operations, a stable schematic form can be isolated, which is defined from operations of abstract location. Thanks to it, all of that particle's uses are put on the same level, as resulting from the variation of its schematic form when it enters into relation with the co-text. The focus can then shift to the understanding of some of the principles that govern the interaction between verb and particle through a sample case study
39
Biyikoglu, Türker, Wim Hordijk, Josef Leydold, Tomaz Pisanski e Peter F. Stadler. "Graph Laplacians, Nodal Domains, and Hyperplane Arrangements". Department of Statistics and Mathematics, Abt. f. Angewandte Statistik u. Datenverarbeitung, WU Vienna University of Economics and Business, 2002. http://epub.wu.ac.at/1036/1/document.pdf.
Testo completoAbstract (sommario):
Eigenvectors of the Laplacian of a graph G have received increasing attention in the recent past. Here we investigate their so-called nodal domains, i.e., the connected components of the maximal induced subgraphs of G on which an eigenvector \psi does not change sign. An analogue of Courant's nodal domain theorem provides upper bounds on the number of nodal domains depending on the location of \psi in the spectrum. This bound, however, is not sharp in general. In this contribution we consider the problem of computing minimal and maximal numbers of nodal domains for a particular graph. The class of Boolean Hypercubes is discussed in detail. We find that, despite the simplicity of this graph class, for which complete spectral information is available, the computations are still non-trivial. Nevertheless, we obtained some new results and a number of conjectures. (author's abstract)Series: Preprint Series / Department of Applied Statistics and Data Processing
40
Wang, Xiaoguang. "Dynamics of McMullen maps and Thurston-type theorems for rational maps with rotation domains". Angers, 2011. http://www.theses.fr/2011ANGE0067.
Testo completoAbstract (sommario):
Cette thèse comporte essentiellement deux parties. La première concerne la connexité locale des ensembles de Julia des fractions rationnelles. Nous utilisons les puzzles de Yoccoz pour étudier les applications de McMullen et montrons que la frontière du bassin de l'infini est toujours une courbe de Jordan. Ceci donne une réponse positive à une question de Devaney. Nous montrons également que ces ensembles de Julia sont localement connexes sauf pour certains cas spéciaux. La deuxième partie concerne la théorie de Thurston sur une caractérisation des fractions rationnelles. Nous établissons un théorème de décomposition : tout revêtement ramifié ayant un domaine de rotation se décompose, suivant une multicourbe, en un nombre fini d'applications de Siegel et de Thurston, tel que les combinatoires et le problème de réalisation rationnelle de ces pièces décomposées dominent essentiellement ceux de l'application originale. En guise d'application, nous démontrons un théorème à la Thurston pour une classe de fractions rationnelles ayant des anneaux d'HermanThe thesis mainly consists of two subjects : the first subject relates to the local connectivity of Julia sets for rational maps. We develop Yoccoz puzzle techniques to study McMullen maps and show that the boundary of the bassin of infinity is always a Jordan curve if the Julia set is not a Cantor set. This give a positive answer to a question of Devaney. We also show the Julia set of McMullen is locally connected except some special cases. The second concerns with Thurston's theory on characterization of rational maps. We establish a "decomposition theorem" : every branched covering with rotation domains can be decomposed along a stable multicurve into finitely many Siegel maps or Thurston maps, such that the combinatorics and rational realizations of these resulting maps essentially dominate the original one. As an application, we prove a Thurston type theorem for a class rational maps with Herman rings
41
Ostier, Pierre. "Hypotheses Domains System : un système d'inférence pour la construction de preuves naturelles et la production d'hypothèses". Université Joseph Fourier (Grenoble), 1997. http://www.theses.fr/1997GRE10257.
Testo completoAbstract (sommario):
Dans cette these, nous presentons un nouveau systeme d'inference pour la logique du premier ordre appele hypotheses domains system (h. D. S. ). Ce systeme d'inference, destine a une utilisation en enseignement de la geometrie, a pour objectifs : - de mettre en uvre des schemas de raisonnement naturels pour l'utilisateur, - de prendre en compte la negation de la logique du premier ordre et d'assurer la completude des deductions, - d'offrir la possibilite de produire des informations utiles a l'utilisateur si une preuve echoue. Le systeme h. D. S. Est constitue de quatre regles d'inference qui operent sur ce que nous appelons des litteraux etendus. Le caractere explicable des preuves obtenues par h. D. S. Resulte de l'interpretation intuitive de ces litteraux etendus et de ces regles d'inference. Nous montrons la consistance et la completude du systeme d'inference et discutons des aspects lies a la calculabilite. Le systeme est compare a d'autres approches existantes dont le systeme modified problem reduction format de plaisted qu'il etend de facon significative. Les capacites abductives du systeme, completes selon le pouvoir d'expression autorise par les litteraux etendus, sont detaillees. Un demonstrateur base sur le systeme h. D. S. A ete mis en uvre en prolog iv et experimente dans le cadre de la preuve de proprietes geometriques. Pour resoudre les problemes d'efficacite, plusieurs strategies, dependantes ou non du domaine d'application, ont ete concues et integrees. La non remise en cause par ces strategies des proprietes theoriques, notamment completude du systeme, est justifiee. Enfin, l'utilisation d'une evaluation sur un modele numerique pour guider la recherche des preuves est decrite, et ses limites actuelles presentees.
42
Mohammadi, Leila. "The study of social egg freezing applying theories of framing and social domains: from the communicative treatment to the perception". Doctoral thesis, Universitat Oberta de Catalunya, 2019. http://hdl.handle.net/10803/667736.
Testo completoAbstract (sommario):
L'objectiu general d'aquest estudi és explorar el tractament comunicatiu que les clíniques de fertilitat fan servir als seus llocs web per oferir tractaments de congelació d'òvuls per raons socials i entendre les percepcions i les experiències de les dones sobre aquest fenomen des de teories de framing i domini social. En coherència amb aquest marc teòric, l'estudi va utilitzar un enfocament de mètodes mixtos: 442 dones van respondre els qüestionaris, incloent-hi 23 usuàries de la tecnologia de congelació d'òvuls. Entre elles, 18 usuàries van ser entrevistades mitjançant entrevistes semiestructurades, amb la posterior anàlisi de contingut i discurs de la informació. S'ha identificat un patró centrat en el màrqueting per als llocs web de clíniques de fertilitat, en què la informació pretenia promoure la congelació dels òvuls, en lloc de ser informativa. La tecnologia social de congelació d'òvuls va ser entesa pels participants com una assegurança per a la seva futura vida fèrtil. Aquest moment adequat va estar relacionat amb la preparació social i emocional. La utilització de teories de framing i del domini social, així com els conceptes de neoliberalisme i consumisme, van demostrar com la percepció de les dones sobre la tecnologia social de congelació d'òvuls està influïda per factors sociològics, incloses experiències individuals; parella i parentiu, i la situació laboral i el lloc de treball.El objetivo general de este estudio es explorar el tratamiento comunicativo que utilizan las clínicas de fertilidad en sus sitios web para ofrecer tratamientos de congelación de óvulos por razones sociales y entender las percepciones y experiencias de las mujeres en relación con este fenómeno desde teorías de framing y dominio social. De acuerdo con este marco teórico, el estudio utilizó un enfoque de métodos mixtos: 442 mujeres respondieron cuestionarios, incluidas 23 usuarias de la tecnología de congelación de óvulos. Entre ellas, 18 usuarias fueron entrevistadas a través de entrevistas semiestructuradas, de las que se realizó un análisis del contenido y el discurso de la información. Se ha identificado un patrón centrado en el marketing para los sitios web de clínicas de fertilidad, en los que la información tenía como objetivo promover la congelación de óvulos en lugar de ser informativa. Los participantes entendieron la tecnología social de congelación de óvulos como un seguro futuro para su vida fértil. Este momento adecuado estaba relacionado con la preparación social y emocional. Utilizando la teoría de framing y el dominio social, así como los conceptos de neoliberalismo y consumismo, el estudio demostró cómo la percepción de las mujeres sobre la tecnología social de congelación de óvulos está influenciada por factores sociológicos que incluyen experiencias individuales; pareja y parentesco, y la situación laboral y el puesto de trabajo.
The overall objective of this study is twofold. It aims to explore the communication strategies fertility clinics use on their websites to offer egg-freezing treatments for social reasons, and to understand women's perception and experience of this phenomenon using theories of framing and social domain. In line with this theoretical framework, the study used a mixed methods approach: questionnaires, responded to by 442 women ¿ including 23 users of egg-freezing technology, and semi-structured interviews with 18 users, with subsequent content and discourse analysis. The results showed a markedly marketing-centred pattern on fertility clinic websites, where the information was aimed more at promoting egg freezing than informing. Social egg-freezing technology was understood by the participants as insurance for their future fertility, and they associated the right moment to try to conceive with being socially and emotionally prepared. Using theories of framing and social domain, as well as concepts of neoliberalism and consumerism, this study demonstrates how women's perception of social egg-freezing technology is influenced by sociological factors as well as individual experiences involving partner and family, their job situation or the workplace.
43
Cherif, Mohamed Raouf. "Theories et procedures numeriques visant a ameliorer l'efficacite du calcul par elements finis". Paris 6, 1986. http://www.theses.fr/1986PA066627.
Testo completoAbstract (sommario):
Le travail que nous presentons consiste a evaluer des theories et des procedures numeriques afin d'ameliorer le calcul par elements finis des problemes poses par les singularites geometriques (problemes numeriques de precision et de convergence). Dans la premiere partie, on a etudie les possibilites d'une modelisation plus fine (par rapport aux modelisations classiques) construite sur une formulation de second ordre permettant de pallier les problemes signales ci-dessus. Dans la deuxieme partie, on s'est interesse a developper des elements de raccordements differents en forme et en raffinement bases sur l'emploi d'une methode de transformation des matrices de rigidite. Dans la troisieme partie, on a teste une procedure de modification de la matrice de rigidite globale assemblee pour traiter les problemes de diversite de profils sur une meme structure standart. Dans la quatrieme partie, nous avons effectue des analyses theorique et numerique confrontees avec une analyse experimentale d'un modele industriel pratique d'une filiere a divers profils de filage en flexion
44
Schwarzbach, Christoph. "Stability of finite element solutions to Maxwell's equations in frequency domain". Doctoral thesis, Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola", 2009. http://nbn-resolving.de/urn:nbn:de:bsz:105-24780.
Testo completoAbstract (sommario):
Eine Standardformulierung der Randwertaufgabe für die Beschreibung zeitharmonischer elektromagnetischer Phänomene hat die Vektor-Helmholtzgleichung für das elektrische Feld zur Grundlage. Bei niedrigen Frequenzen führt der große Nullraum des Rotationsoperators zu einem instabilen Lösungsverhalten. Wird die Randwertaufgabe zum Beispiel mit Hilfe der Methode der Finiten Elemente in ein lineares Gleichungssystem überführt, äußert sich die Instabilität in einer schlechten Konditionszahl ihrer Koeffizientenmatrix. Eine stabilere Formulierung wird durch die explizite Berücksichtigung der Kontinuitätsgleichung erreicht. Zur numerischen Lösung der Randwertaufgaben wurde eine Finite-Elemente-Software erstellt. Sie berücksichtigt unter anderem unstrukturierte Gitter, räumlich variable, anisotrope Materialparameter sowie die Erweiterung der Maxwell-Gleichungen durch Perfectly Matched Layers. Die Software wurde anhand von Anwendungen in der marinen Geophysik erfolgreich getestet. Insbesondere demonstriert die Einbeziehung von Seebodentopographie in Form einer stetigen Oberflächentriangulierung die geometrische Flexibilität der SoftwareThe physics of time-harmonic electromagnetic phenomena can be mathematically described by boundary value problems. A standard approach is based on the vector Helmholtz equation in terms of the electric field. The curl operator involved has a large, non-trivial kernel which leads to an instable solution behaviour at low frequencies. If the boundary value problem is solved approximately using, e. g., the finite element method, the instability expresses itself by a badly conditioned coefficient matrix of the ensuing system of linear equations. A stable formulation is obtained by taking the continuity equation explicitly into account. In order to solve the boundary value problem numerically a finite element software package has been implemented. Its features comprise, amongst others, the treatment of unstructured meshes and piecewise polynomial, anisotropic constitutive parameters as well as the extension of Maxwell’s equations to the Perfectly Matched Layer. Successful application of the software is demonstrated with examples from marine geophysics. In particular, the incorporation of seafloor topography by a continuous surface triangulation illustrates the geometric flexibility of the software
45
Otto, Andreas. "Frequency domain methods for the analysis of time delay systems". Doctoral thesis, Universitätsbibliothek Chemnitz, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-208749.
Testo completoAbstract (sommario):
In this thesis a new frequency domain approach for the analysis of time delay systems is presented. After linearization of a nonlinear delay differential equation (DDE) with constant distributed delay around a constant or periodic reference solution the so-called Hill-Floquet method can be used for the analysis of the resulting linear DDE. In addition, systems with fast or slowly time-varying delays, systems with variable transport delays originating from a transport with variable velocity, and the corresponding spatially extended systems are presented, which can be also analyzed with the presented method. The newly introduced Hill-Floquet method is based on the Hill’s infinite determinant method and enables the transformation of a system with periodic coefficients to an autonomous system with constant coefficients. This makes the usage of a variety of existing methods for autonomous systems available for the analysis of periodic systems, which implies that the typical calculation of the monodromy matrix for the time evolution of the solution over the principle period is no longer required. In this thesis, the Chebyshev collocation method is used for the analysis of the autonomous systems. Specifically, in this case the periodic part of the solution is expanded in a Fourier series and the exponential behavior of the solution is approximated by the discrete values of the Fourier coefficients at the Chebyshev nodes, whereas in classical spectral or pseudo-spectral methods for the analysis of linear periodic DDEs the complete solution is expanded in terms of basis functions. In the last part of this thesis, new results for three applications with time delay effects are presented, which were analyzed with the presented methods. On the one hand, the occurrence of diffusion-driven instabilities in reaction-diffusion systems with delay is investigated. It is shown that wave instabilities are possible already for single-species reaction diffusion systems with distributed or time-varying delay. On the other hand, the stability of metal cutting vibrations at machine tools is analyzed. In particular, parallel orthogonal turning processes with multiple discrete delays and turning processes with a time-varying delay due to a spindle speed variation are studied. Finally, the stability of the synchronized solution in networks with heterogeneous coupling delays is studied. In particular, the eigenmode expansion for synchronized periodic orbits is derived, which includes an extension of the classical master stability function to networks with heterogeneous coupling delays. Numerical results are shown for a network of Hodgkin-Huxley neurons with two delays in the couplingIn dieser Dissertation wird ein neues Verfahren zur Analyse von Systemen mit Totzeiten im Frequenzraum vorgestellt. Nach Linearisierung einer nichtlinearen retardierten Differentialgleichung (DDE) mit konstanter verteilter Totzeit um eine konstante oder periodische Referenzlösung kann die sogenannte Hill-Floquet Methode für die Analyse der resultierende linearen DDE angewendet werden. Darüber hinaus werden Systeme mit schnell oder langsam variierender Totzeit, Systeme mit einer variablen Totzeit, resultierend aus einem Transport mit variabler Geschwindigkeit, und entsprechende räumlich ausgedehnte Systeme vorgestellt, welche ebenfalls mit der vorgestellten Methode analysiert werden können. Die neu eingeführte Hill-Floquet Methode basiert auf der Hillschen unendlichen Determinante und ermöglicht die Transformation eines Systems mit periodischen Koeffizienten auf ein autonomes System mit konstanten Koeffizienten. Dadurch können zur Analyse periodischer Systeme auch eine Vielzahl existierender Methoden für autonome Systeme genutzt werden und die Berechnung der Monodromie-Matrix für die Lösung des Systems über eine Periode entfällt. In dieser Arbeit wird zur Analyse des autonomen Systems die Tschebyscheff-Kollokationsmethode verwendet. Im Speziellen wird bei diesem Verfahren der periodische Teil der Lösung in einer Fourierreihe entwickelt und das exponentielle Verhalten durch die Werte der Fourierkoeffizienten an den Tschebyscheff Knoten approximiert, wohingegen bei klassischen spektralen Verfahren die komplette Lösung in bestimmten Basisfunktionen entwickelt wird. Im Anwendungsteil der Arbeit werden neue Ergebnisse für drei Beispielsysteme präsentiert, welche mit den vorgestellten Methoden analysiert wurden. Es wird gezeigt, dass Welleninstabilitäten schon bei Einkomponenten-Reaktionsdiffusionsgleichungen mit verteilter oder variabler Totzeit auftreten können. In einem zweiten Beispiel werden Schwingungen an Werkzeugmaschinen betrachtet, wobei speziell simultane Drehbearbeitungsprozesse und Prozesse mit Drehzahlvariationen genauer untersucht werden. Am Ende wird die Synchronisation in Netzwerken mit heterogenen Totzeiten in den Kopplungstermen untersucht, wobei die Zerlegung in Netzwerk-Eigenmoden für synchrone periodische Orbits hergeleitet wird und konkrete numerische Ergebnisse für ein Netzwerk aus Hodgkin-Huxley Neuronen gezeigt werden
46
Attou, Djelloul. "Theorie asymptotique des plaques minces electro ou magnetoelastiques". Paris 6, 1988. http://www.theses.fr/1988PA066029.
Testo completoAbstract (sommario):
La methode d'integration asymptotique de gol'denveizer et le formalisme variationnel de ciarlet et destuynder (connu aussi comme la technique du zoom) ont montre leur efficacite pour etablir des theories de corps elastiques elances tels que les plaques minces. La meme idee est utilisee ici pour obtenir differentes approximations a la theorie des plaques electro ou magnetoelastiques. La metode et les resultats critiques sont illustres sur trois exemples. Le premier, traite en quasi-electrostatiqus, concerne les plaques piezoelectriques. Le second, traite en quasi-magnetostatique, concerne la theorie des plaques elastiques ferromagnetiques (non conductrices). Le troisieme cas s'applique aux plaques conductrices de courant electrique
47
Hamadi, Riad. "Méthodes de décompositions de domaines pour la résolution des CSP : application au système OSIRIS". Université Joseph Fourier (Grenoble ; 1971-2015), 1997. http://www.theses.fr/1997GRE10203.
Testo completoAbstract (sommario):
La premiere partie de ce travail presente une approche de decomposition de domaines pour resoudre les problemes de satisfaction de contraintes (csp) discrets et continus lineaires. L'approche repose sur : 1 - la representation d'un csp par un graphe appele la micro-structure du csp. 2- la decomposition du csp en sous-csp definis a partir de cliques maximales de la micro-structure. Dans la premiere partie, on presente la methode de decomposition de domaine developpee par jegou en 1993 pour resoudre les csp binaires discrets. Puis on propose une extension de cette methode pour resoudre les csp discrets n-aires et les csp continus lineaires. La seconde partie de ce travail presente l'utilisation de la methode de decomposition de domaine pour definir et resoudre les csp discrets et continus lineaires dans un systeme de representation de connaissances, osiris, ainsi que l'utilisation de micro-structures pour le classement d'objets.
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Otto, Michael. "Symplectic convexity theorems and applications to the structure theory of semisimple Lie groups". Connect to this title online, 2004. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1084986339.
Testo completoAbstract (sommario):
Thesis (Ph. D.)--Ohio State University, 2004.Title from first page of PDF file. Document formatted into pages; contains v, 88 p. Includes bibliographical references (p. 87-88). Available online via OhioLINK's ETD Center
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Nägele, Philipp [Verfasser], e Michael [Akademischer Betreuer] Růžička. "Monotone operator theory for unsteady problems on non-cylindrical domains = Monotone Operatoren-Theorie für instationäre Probleme auf nicht-zylindrischen Gebieten". Freiburg : Universität, 2015. http://d-nb.info/111932758X/34.
Testo completo
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KRASTEV, KRASSIMIR. "Structures periodiques a une et deux dimensions pour le domaine des rayons x : miroirs multicouches, reseaux multicouches - theorie, modelisation, experience". Paris 6, 1997. http://www.theses.fr/1997PA066404.
Testo completoAbstract (sommario):
Ce travail concerne une etude theorique et experimentale des dispositifs spectroscopiques pour le domaine des rayons x : des reseaux lamellaires graves dans des structures multicouches periodiques. Leur efficacite a ete calculee dans des conditions generales d'incidence de l'onde electromagnetique, ce que l'on appelle generalement incidence conique. Le probleme des instabilites des calculs observees jusqu'a present a ete resolu grace a la methode de propagation des champs a travers la structure stratifiee proposee. Cette methode est communement appele methode r. La theorie de l'incidence conique, developpee dans plusieurs laboratoires de recherche dans le monde pour des reseaux massifs de diffraction a ete modifiee et appliquee avec succes dans l'etude des reseaux multicouches. La methode de propagation r precedemment mentionnee est indispensable dans ce type d'etude. Les resultats de la modelisation sont en parfaite correspondance avec les resultats experimentaux obtenus en utilisant le reflectometre du groupe d'optique x, du laboratoire de chimie physique, matiere et rayonnement. Une etude experiementale du spectre des sources inconnues de rayonnement a l'aide des reseaux multicouches grace a l'effet polychromateur est presentee. Un parallele entre les resultats obtenus dans les etudes des structures periodiques a deux et trois dimensions, dites cristaux photoniquese et les resultats theoriques concernant les reseaux multicouches a ete etabli.