Дисертації з теми "Analytic perturbations"
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Coiculescu, Ion. "Dynamics, Thermodynamic formalism and Perturbations of Transcendental Entire Functions of Finite Singular Type." Thesis, University of North Texas, 2005. https://digital.library.unt.edu/ark:/67531/metadc4783/.
Повний текст джерелаGatse, Franchel. "Spectre ordonné et branches analytiques d'une surface qui dégénère sur un graphe." Electronic Thesis or Diss., Orléans, 2020. http://www.theses.fr/2020ORLE3205.
Повний текст джерелаIn this work, we give a general framework of Riemannian surfaces that can degenerate on metric graphs and that we call surfaces made from cylinders and connecting pieces. The latter depend on a parameter t that describes the degeneration. When t goes to 0, the waists of the cylinders go to 0 but their lengths stay fixed. We thus obtain the edges of the limiting graph. The connecting pieces are squeezed in all directions and degenerate on the vertices of the limiting graph. We then study the asymptotic behaviour of the spectrum of these surfaces when t varies from two different points of view, considering the spectrum either as a sequence of ordered eigenvalues or as a collection of analytic eigenbranches. In the case of ordered eigenvalues, we recover a rather classical statement, and prove that the spectrum converges to the spectrum of the limiting object. The study of the analytic eigenbranches is more original. We prove that any such eigenbranch converges and we give a characterisation of the possible limits. These results apply to translation surfaces on which there is a completely periodic direction
Neuner, Christoph. "On Supersingular Perturbations." Doctoral thesis, Stockholms universitet, Matematiska institutionen, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-147396.
Повний текст джерелаAt the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Manuscript. Paper 4: Manuscript.
Pond, Jarrad W. T. "Perturbation analysis of fluctuations in the universe on large scales, including decaying solutions and rotational velocities." Honors in the Major Thesis, University of Central Florida, 2009. http://digital.library.ucf.edu/cdm/ref/collection/ETH/id/1309.
Повний текст джерелаBachelors
Sciences
Physics
Hiller, Steven Mark. "Automatic acoustic analysis of waveform perturbations." Thesis, University of Edinburgh, 1985. http://hdl.handle.net/1842/18962.
Повний текст джерелаROCCHI, Marta. "Ecosystem response to perturbations: insight from qualitative analysis." Doctoral thesis, Università degli studi di Ferrara, 2017. http://hdl.handle.net/11392/2488077.
Повний текст джерелаI cambiamenti ambientali in atto richiedono un miglioramento delle conoscenze su struttura e funzionamento dei sistemi naturali attraverso un approccio olistico. Una visione d’insieme potrebbe aiutare a comprendere meglio la risposta degli ecosistemi alle perturbazioni. E’ stato provato che lo studio dei network ecologici è utile per comprendere la struttura e le dinamiche degli ecosistemi. In questa tesi presento due tecniche modellistiche: l’analisi topologica di food web (capitolo 2) e la loop analysis (capitolo 3 e 4). Entrambi gli studi privilegiano l’analisi qualitativa a quella quantitativa per superare la mancanza di dati. Nel capitolo 2 ho considerato alcune caratteristiche topologiche per lo studio del funzionamento dell’ecosistema di Baja California Sur. Ho identificato, attraverso gli indici di centralità, le specie chiave e analizzato la resilienza del sistema alla rimozione delle specie definite più vulnerabili (es. precedente classificazione di alto, medio e basso rischio). Gli effetti sono stati valutati attraverso indici globali. I risultati evidenziano la resilienza strutturale della food web alle rimozioni, ma anche che la rimozione delle specie più vulnerabili cambia significatamente alcuni attributi del sistema rispetto alle rimozioni random. Nel capitolo 3 ho valutato l’evoluzione dell’ecosistema del Mar Nero nel periodo 1960-1990 attraverso la loop analysis. I modelli qualitativi indagati ricostruiscono la struttura dei legami dell’intera comunità. Ho validato i risultati emersi con indagini statistiche sulle serie temporali di biomasse per capire come la struttura delle interazioni può spiegare le variazioni nei livelli di biomassa delle variabili e quali ipotesi possono essere fatte sui drivers e i meccanismi responsabili dei cambiamenti. Nel capitolo 4 ho costruito un database di food web reali e random, che ho studiato attraverso la loop analysis, per capire come un input positivo sulle specie basali e apicali si ripercuote rispettivamente sulle specie apicali e basali. Lo scopo era quello di identificare possibili differenze nella propagazione degli effetti indiretti in risposta a input positivi che si verificano agli estremi delle food web. Ho confrontato sistemi reali (marini, terrestri e di acqua dolce) con networks random. Ho trovato una sovrarappresentazione di predizioni positive (aumento dell’abbondanza delle specie) e una sottorappresentazione di predizione negative per le specie apicali a seguito di un input positivo sulle specie basali, sia nei sistemi reali che in quelli random. Considerando questi ultimi lo stesso trend (sovrarappresentazione di segni positivi e sottorappresentazione di segni negativi) è stato trovato nelle predizioni riguardanti la risposta delle specie basali a seguito di un input sulle specie apicali. Ho mostrato che questi risultati sono dovuti alla struttura topologica delle food web (es. il numero e la lunghezza dei percorsi trofici) piuttosto che alla forza delle interazioni. Sembra che le risposte delle specie apicali a seguito di perturbazioni delle specie basali siano prevedibili, al contrario delle risposte delle specie basali a seguito di un input sulle apicali. Questi risultati sono particolarmente rilevanti e interessanti considerando l’importanza delle specie basali e apicali come target degli impatti antropici. Questa tesi contribuisce allo sviluppo di un percorso verso: 1)la comprensione degli effetti di disturbo sulle comunità ecologiche e sugli ecosistemi; 2)una migliore comprensione delle interazioni di controllo top-down e bottom-up; 3)la capacità di affrontare l'incertezza per valutare la risposta delle comunità e degli ecosistemi di fronte al disturbo. Nonostante l’uso di metodologie relativamente semplici che si concentrano sulla disposizione qualitativa delle interazioni trofiche, ho dimostrato che vi sono casi in cui anche lo studio di dati qualitativi può essere di cruciale importanza in termini di gestione.
Chang, Xiao-Wen. "Perturbation analysis of some matrix factorizations." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape16/PQDD_0023/NQ29906.pdf.
Повний текст джерелаDendievel, Sarah. "Skip-free markov processes: analysis of regular perturbations." Doctoral thesis, Universite Libre de Bruxelles, 2015. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209050.
Повний текст джерелаThis thesis focuses on a category of methods, called matrix analytic methods, that has gained much interest because of good computational properties for the analysis of a large family of stochastic processes. Those methods are used in this work in order i) to analyze the effect of regular perturbations of the transition matrix on the stationary distribution of skip-free Markov processes; ii) to determine transient distributions of skip-free Markov processes by performing regular perturbations.
In the class of skip-free Markov processes, we focus in particular on quasi-birth-and-death (QBD) processes and Markov modulated fluid models.
We first determine the first order derivative of the stationary distribution - a key vector in Markov models - of a QBD for which we slightly perturb the transition matrix. This leads us to the study of Poisson equations that we analyze for finite and infinite QBDs. The infinite case has to be treated with more caution therefore, we first analyze it using probabilistic arguments based on a decomposition through first passage times to lower levels. Then, we use general algebraic arguments and use the repetitive block structure of the transition matrix to obtain all the solutions of the equation. The solutions of the Poisson equation need a generalized inverse called the deviation matrix. We develop a recursive formula for the computation of this matrix for the finite case and we derive an explicit expression for the elements of this matrix for the infinite case.
Then, we analyze the first order derivative of the stationary distribution of a Markov modulated fluid model. This leads to the analysis of the matrix of first return times to the initial level, a charactersitic matrix of Markov modulated fluid models.
Finally, we study the cumulative distribution function of the level in finite time and joint distribution functions (such as the level at a given finite time and the maximum level reached over a finite time interval). We show that our technique gives good approximations and allow to compute efficiently those distribution functions.
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Un processus markovien est défini par sa matrice de transition. Un processus markovien sans sauts est un processus stochastique de Markov défini par un niveau qui ne peut changer que d'une unité à la fois, soit vers le haut, soit vers le bas. Une perturbation régulière est une modification suffisamment petite d'un ou plusieurs paramètres qui ne modifie pas qualitativement le modèle.
Dans ce travail, nous utilisons des méthodes matricielles pour i) analyser l'effet de perturbations régulières de la matrice de transition sur le processus markoviens sans sauts; ii) déterminer des lois de probabilités en temps fini de processus markoviens sans sauts en réalisant des perturbations régulières.
Dans la famille des processus markoviens sans sauts, nous nous concentrons en particulier sur les processus quasi-birth-and-death (QBD) et sur les files fluides markoviennes.
Nous nous intéressons d'abord à la dérivée de premier ordre de la distribution stationnaire – vecteur clé des modèles markoviens – d'un QBD dont on modifie légèrement la matrice de transition. Celle-ci nous amène à devoir résoudre les équations de Poisson, que nous étudions pour les processus QBD finis et infinis. Le cas infini étant plus délicat, nous l'analysons en premier lieu par des arguments probabilistes en nous basant sur une décomposition par des temps de premier passage. En second lieu, nous faisons appel à un théorème général d'algèbre linéaire et utilisons la structure répétitive de la matrice de transition pour obtenir toutes les solutions à l’équation. Les solutions de l'équation de Poisson font appel à un inverse généralisé, appelé la matrice de déviation. Nous développons ensuite une formule récursive pour le calcul de cette matrice dans le cas fini et nous dérivons une expression explicite des éléments de cette dernière dans le cas infini.
Ensuite, nous analysons la dérivée de premier ordre de la distribution stationnaire d'une file fluide markovienne perturbée. Celle-ci nous amène à développer l'analyse de la matrice des temps de premier retour au niveau initial – matrice caractéristique des files fluides markoviennes.
Enfin, dans les files fluides markoviennes, nous étudions la fonction de répartition en temps fini du niveau et des fonctions de répartitions jointes (telles que le niveau à un instant donné et le niveau maximum atteint pendant un intervalle de temps donné). Nous montrerons que cette technique permet de trouver des bonnes approximations et de calculer efficacement ces fonctions de répartitions.
Doctorat en Sciences
info:eu-repo/semantics/nonPublished
Preciso, Luca. "Perturbation Analysis of the Conformal Sewing Problem and Related Problems." Doctoral thesis, Università degli studi di Padova, 1998. http://hdl.handle.net/11577/3425905.
Повний текст джерелаOnen, Onursal. "Analytical Modeling, Perturbation Analysis and Experimental Characterization of Guided Surface Acoustic Wave Sensors." Scholar Commons, 2013. http://scholarcommons.usf.edu/etd/4555.
Повний текст джерелаKnudson, Wade E. "Orbital perturbation analysis of earth-crossing asteroids." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1995. http://handle.dtic.mil/100.2/ADA306616.
Повний текст джерелаThesis advisor(s): I.M. Ross. "December 1995." Includes bibliographical references. Also available online.
Adams, Richelle Vive-Anne. "Infinitesimal Perturbation Analysis for Active Queue Management." Diss., Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/19844.
Повний текст джерелаWong, Chin Pin. "Kato's Perturbation Theorem and honesty theory." Thesis, University of Oxford, 2015. https://ora.ox.ac.uk/objects/uuid:c72c308b-d96d-4e31-a854-f2a10e99eeb6.
Повний текст джерелаMichalski, Milosz R. "Perturbation theory for the topological pressure in analytic dynamical systems." Diss., Virginia Tech, 1990. http://hdl.handle.net/10919/39745.
Повний текст джерелаPh. D.
Kawelke, Jens. "Perturbation and error analysis considerations in robust control." Thesis, University of Leicester, 1997. http://hdl.handle.net/2381/30177.
Повний текст джерелаDuTôt, Meghan. "Comparing cell polarization models using local perturbation analysis." Thesis, University of British Columbia, 2014. http://hdl.handle.net/2429/46357.
Повний текст джерелаSutherland, Andrew Mackinnon. "Automatic speaker verification based on waveform perturbation analysis." Thesis, University of Edinburgh, 1989. http://hdl.handle.net/1842/13041.
Повний текст джерелаShankar, Uday J. "Singular-perturbation analysis of climb-cruise-dash optimization." Thesis, Virginia Tech, 1985. http://hdl.handle.net/10919/45736.
Повний текст джерелаMaster of Science
PIETROBON, DAVIDE. "Making the best of cosmological perturbations: theory and data analysis." Doctoral thesis, Università degli Studi di Roma "Tor Vergata", 2010. http://hdl.handle.net/2108/1197.
Повний текст джерелаCosmology has entered the precision epoch thanks to several very accurate experiments. Cosmologists now have access to an array of tools to test the cosmological concordance model and constrain its parameters; the Cosmic Microwave Background radiation (CMB), in particular, has been playing a crucial role in this ambition. Many questions remain nonetheless unanswered, especially concerning the physics of the early Universe, the infl ationary mechanism which set the initial conditions for the Universe expansion, and the nature of the late time acceleration of the Universe expansion. My research contributes to both of these sub jects, the common ground being the development of a statistical tool - needlets, a new "frame" on the sphere - to analyse the CMB. By means of needlets, we measure the Integrated Sachs Wolfe effect by cross-correlating WMAP and NVSS datasets and characterise dark energy properties using a phenomenological fluid model. Motivated by our findings, we study in detail a parameterisation of the dark components, dark matter and dark energy, which makes use of an affine equation of state, constraining the parameters of the model by combining WMAP and SDSS datasets. We apply needlets to the WMAP 5-year data release testing the Gaussianity of the CMB perturbations. Our approach is twofold: we first focus on the maps, detecting anomalous spots located in the southern hemisphere and check their effect on the angular power spectrum. We next measure the needlet three-point correlation function (bispectrum) and characterise it in terms of its overall amplitude, constraining the primordial fNL parameter, and considering its properties according to the geometry of the triangle configurations which contribute to the total power. We find a significant anomaly in the isosceles confi gurations, again in the southern hemisphere. Finally we focus on the construction of an optimal estimator for the (needlets) bispectrum, taking into account foreground residuals due mainly to Galactic emission.
Lemaitre, Paul. "Analyse de sensibilité en fiabilité des structures." Thesis, Bordeaux, 2014. http://www.theses.fr/2014BORD0061/document.
Повний текст джерелаThis thesis' subject is sensitivity analysis in a structural reliability context. The general framework is the study of a deterministic numerical model that allows to reproduce a complex physical phenomenon. The aim of a reliability study is to estimate the failure probability of the system from the numerical model and the uncertainties of the inputs. In this context, the quantification of the impact of the uncertainty of each input parameter on the output might be of interest. This step is called sensitivity analysis. Many scientific works deal with this topic but not in the reliability scope. This thesis' aim is to test existing sensitivity analysis methods, and to propose more efficient original methods. A bibliographical step on sensitivity analysis on one hand and on the estimation of small failure probabilities on the other hand is first proposed. This step raises the need to develop appropriate techniques. Two variables ranking methods are then explored. The first one proposes to make use of binary classifiers (random forests). The second one measures the departure, at each step of a subset method, between each input original density and the density given the subset reached. A more general and original methodology reflecting the impact of the input density modification on the failure probability is then explored.The proposed methods are then applied on the CWNR case, which motivates this thesis
Kyriakopoulos, Nikos. "Flocking in active matter systems : structure and response to perturbations." Thesis, University of Aberdeen, 2016. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=231666.
Повний текст джерелаLi, Yuemeng. "Spectral Analysis of Directed Graphs using Matrix Perturbation Theory." Thesis, The University of North Carolina at Charlotte, 2017. http://pqdtopen.proquest.com/#viewpdf?dispub=10618933.
Повний текст джерелаThe spectral space of the adjacency matrix contains important structural information of a given network (graph), where such information can be leveraged in developing a variety of algorithms in applications such as graph partition, structural hierarchy discovery, and anomaly detection. Although many prominent works have laid the foundation for studying the graph spectra, it is still challenging to analyze the spectral space properties for directed graphs due to possible complex valued decompositions. Matrix factorization techniques such as Laplacian and normalized Laplacian have been widely adopted to study the associated spectral spaces, but network structural properties may not be well preserved in those spectral spaces due to transformations.
In this dissertation work, we explore the adjacency eigenspace of directed graphs using matrix perturbation theory and examine the relationships between graph structures and the spectral projection patterns. We study how to detect dominant structures such as clusters or anomalous nodes by establishing a connection between the connectivity of nodes and the geometric relationships in the adjacency eigenspace. We leverage selected key results from perturbation theory, linear algebra and graph theory as our tools to derive theoretical results that help to elaborate observed graph spectral projection patterns. In order to validate our theoretical results, novel algorithms including spectral clustering for both signed and unsigned networks, asymmetry analysis for network dominance, and anomaly analysis for streaming network data are developed and tested on both synthetic and real datasets. The empirical evaluation results suggest that our algorithms performs better when compared with existing state-of-the-art methods.
Luo, Min. "Perturbation analysis and optimization of fork-join queueing networks." Diss., Georgia Institute of Technology, 1992. http://hdl.handle.net/1853/14901.
Повний текст джерелаAhmad, M. Masood. "Sensitivity estimates via perturbation analysis in power system simulations." Diss., Georgia Institute of Technology, 1993. http://hdl.handle.net/1853/15408.
Повний текст джерелаIvandich, Steven A. "Performance analysis of adaptive arrays with projected perturbation sequences." Thesis, Curtin University, 1999. http://hdl.handle.net/20.500.11937/94.
Повний текст джерелаIvandich, Steven A. "Performance analysis of adaptive arrays with projected perturbation sequences." Curtin University of Technology, Australian Telecommunications Research Institute, 1999. http://espace.library.curtin.edu.au:80/R/?func=dbin-jump-full&object_id=10431.
Повний текст джерелаBennett, James Cameron, and james bennett@student rmit edu au. "Mathematical Analysis of Film Blowing." RMIT University. Mathematical and Geospatial Sciences, 2008. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20081128.115021.
Повний текст джерелаFarina, Sofia. "A physical interpretation of network laplacian: role of perturbations and masses." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2018. http://amslaurea.unibo.it/16345/.
Повний текст джерелаMetelkina, Asya. "Perturbations à oscillations lentes de l'opérateur de Schrödinger périodique." Phd thesis, Université Paris-Nord - Paris XIII, 2011. http://tel.archives-ouvertes.fr/tel-00714033.
Повний текст джерелаEttenhuber, Christian. "Computational approaches for metabolic flux analysis in 13C perturbation experiments." [S.l. : s.n.], 2005. http://deposit.ddb.de/cgi-bin/dokserv?idn=974209961.
Повний текст джерелаPang, Wyming Lee. "Quantitative analysis of genetic expression responses to dynamic microenvironmental perturbation." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2007. http://wwwlib.umi.com/cr/ucsd/fullcit?p3245319.
Повний текст джерелаTitle from first page of PDF file (viewed March 2, 2007). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references (p. 320-337).
Howell, William Casey. "Simulation optimization of traffic light signal timings via perturbation analysis." College Park, Md. : University of Maryland, 2006. http://hdl.handle.net/1903/3779.
Повний текст джерелаThesis research directed by: Applied Mathematics and Scientific Computation Program. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
Koreshi, Zafar-Ullah. "Monte Carlo perturbation applications for nuclear fusion reactor blanket analysis." Thesis, University of Cambridge, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.386090.
Повний текст джерелаHoffmann, Peter, and Christoph Jacobi. "Analysis of planetary waves seen in ionospheric total electron content (TEC) perturbations." Universität Leipzig, 2006. https://ul.qucosa.de/id/qucosa%3A15490.
Повний текст джерелаThe DLR Neustrelitz regularly produces maps of the total total electron content (TEC) on a global scale using the navigation satellite systems GPS and GLONASS to forecast space weather. In this study we turn our attention to the higher middle latitudes TEC variations during September to November 2004 in a long-period range of several days with a zonal wavenumber up to 5. The results are compared with a planetary wave analysis using assimilated stratospheric data, mesosphere/lower thermosphere radar temperature data at Collm observatory (51.3◦N, 13.0◦E) and the ionosonde observed critical plasma frequency of the F2-layer (f0F2) at Juliusruh (54.6◦N, 13.4◦E) to investigate the meteorological influences on ionospheric variability.
Nardone, Marco. "Analysis of Voice Perturbations Using an Asymmetric Model of the Vocal Folds." Bowling Green State University / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1183755009.
Повний текст джерелаHoffmann, Peter, and Christoph Jacobi. "Analysis of planetary waves seen in ionospheric total electron content (TEC) perturbations." Universitätsbibliothek Leipzig, 2017. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-221930.
Повний текст джерелаThe DLR Neustrelitz regularly produces maps of the total total electron content (TEC) on a global scale using the navigation satellite systems GPS and GLONASS to forecast space weather. In this study we turn our attention to the higher middle latitudes TEC variations during September to November 2004 in a long-period range of several days with a zonal wavenumber up to 5. The results are compared with a planetary wave analysis using assimilated stratospheric data, mesosphere/lower thermosphere radar temperature data at Collm observatory (51.3◦N, 13.0◦E) and the ionosonde observed critical plasma frequency of the F2-layer (f0F2) at Juliusruh (54.6◦N, 13.4◦E) to investigate the meteorological influences on ionospheric variability
Anselmi, Stefano. "Semi-analytical approaches to cosmological perturbations in the mildly non-linear regime." Doctoral thesis, Università degli studi di Padova, 2011. http://hdl.handle.net/11577/3421616.
Повний текст джерелаUna delle sfide più importanti della cosmologia riguarda la comprensione della formazione e dell'evoluzione delle strutture. Questi processi fisici ci forniscono informazioni fondamentali sulla natura del nostro Universo. L'analisi della crescita delle perturbazioni di densita' e di velocita' ci offre un'importante opportunita' per quantificare con piu' accuratezza la percentuale di materia oscura o comprendere le cause che guidano l'espansione accelerata dell'Universo (il cosiddetto problema dell'Energia Oscura). A grandi scale la crescita delle fluttuazioni puo' essere descritta con la teoria delle perturbazioni lineari. I risultati a queste scale sono stati largamente confermati dalla simulazioni numeriche e utilizzati nell'analisi dei dati reali. Le future osservazioni di galassie ci permetteranno di porre dei vincoli sulla crescita delle perturbazioni con una precisione mai raggiunta prima. Inoltre, informazioni fisiche rilevanti sono presenti a scale piu' piccole di O(100 Mpc), dove le strutture sono molto piu' raggruppate e la teoria delle perturbazioni lineare non e' piu' valida. Le tecniche piu' utilizzate per affrontare il problema della formazione delle strutture sono le simulazioni ad N-corpi, anche se mostrano alcuni inconvenienti. Infatti, le simulazioni rendono piu' difficile la comprensione della fisica rispetto all'approccio analitico e semi-analitico. Inoltre le simulazioni sono limitate dal lungo tempo di calcolo che caratterizza questi studi. Date le precedenti motivazioni, differenti approcci semi-analitici al problema sono apparsi negli ultimi anni. Essi sono basati sulla possibilita' di riformulare la serie di perturbazioni cosmologiche in maniera appropriata. La maggior parte di queste nuove teorie riorganizza l'espansione in serie ridefinendo le grandezze fondamentali dello sviluppo perturbativo. In particolare il propagatore non lineare assume un ruolo fondamentale ed e' stato calcolato analiticamente con approcci differenti. Esso rappresenta il cross-correlatore tra le perturbazioni finali e iniziali di densita', o di velocita'. L'obiettivo principale di questa tesi e' quello di andare oltre le approssimazioni note relative al calcolo del propagatore non lineare facendo uso delle equazioni esatte di evoluzione per il propagatore. Abbiamo sviluppato e motivato un metodo di approssimazione analitico che ci ha permesso di includere una piu' ampia classe di correzioni perturbative che sono state trascurate in altre risommazioni analitiche. In particolare, questo metodo ci permette di considerare le correzioni date da un generico spettro di potenza non lineare. Inoltre abbiamo calcolato il propagatore non lineare considerando due differenti approssimazioni per lo spettro di potenza esatto. Questo problema e' stato trattato sia con tecniche analitiche che numeriche. Come risultato generale, abbiamo trovato che gli approcci predenti portano ad un risultato errato per quanto riguarda il segno delle correzioni del propagatore. Questo chiarisce un problema controverso e suggerisce che sono necessari ulteriori confronti con le simulazioni a N-corpi. Abbiamo trovato che le nuove correzioni sono significative alle scale rilevanti e quindi non possono essere trascurate in uno schema di risommazione che mira a raggiungere un'accuratezza compatibile con le future osservazioni astrofisiche. Inoltre proponiamo un metodo per calcolare lo spettro di potenza tenendo conto di questi risultati.
Blenkinsop, Glen M. "Postural control : learning to balance and responses to mechanical and sensory perturbations." Thesis, Loughborough University, 2015. https://dspace.lboro.ac.uk/2134/17109.
Повний текст джерелаDalla, Riva Matteo. "Potential theoretic methods for the analysis of singularly perturbed problems in linearized elasticity." Doctoral thesis, Università degli studi di Padova, 2008. http://hdl.handle.net/11577/3426270.
Повний текст джерелаBirman, Michael, Tatyana Suslina, and tanya@petrov stoic spb su. "Threshold Effects near the Lower Edge of the Spectrum for Periodic." ESI preprints, 2001. ftp://ftp.esi.ac.at/pub/Preprints/esi992.ps.
Повний текст джерелаCivin, Damon. "Stability of charged rotating black holes for linear scalar perturbations." Thesis, University of Cambridge, 2015. https://www.repository.cam.ac.uk/handle/1810/247397.
Повний текст джерелаHamouda, Makram. "Perturbations singulières pour des EDP linéaires et non linéaires en presence de discontinuités." Phd thesis, Université Paris Sud - Paris XI, 2001. http://tel.archives-ouvertes.fr/tel-00001931.
Повний текст джерелаWiklund, Susanne. "Spectroscopic data and multivariate analysis : tools to study genetic perturbations in poplar trees." Doctoral thesis, Umeå : Department of Chemistry, Umeå Univ, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-1396.
Повний текст джерелаCox, Neil Bernard. "Assessment of vocal pathology through computerized analysis of perturbation in vowels." Thesis, University of British Columbia, 1988. http://hdl.handle.net/2429/29081.
Повний текст джерелаApplied Science, Faculty of
Electrical and Computer Engineering, Department of
Graduate
Abedi, Vida. "System-identification of gene regulatory networks by systematic gene perturbation analysis." Thesis, University of Ottawa (Canada), 2009. http://hdl.handle.net/10393/28254.
Повний текст джерелаKebarighotbi, Ali. "Perturbation analysis in fluid scheduling and optimization of stochastic hybrid systems." Thesis, Boston University, 2012. https://hdl.handle.net/2144/31576.
Повний текст джерелаPLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at open-help@bu.edu. Thank you.
This dissertation is dedicated to optimization of Stochastic Hybrid Systems (SHS). The concentration is on both online optimization of these systems and extending the known optimal policies in Discrete-Event Systems (DES) to a broader context of SHS. A SHS involves both continuous and discrete dynamics and is suitable for modeling almost any physical system of interest. The first part of this dissertation focuses on applications of SHS and, particularly, a subclass known as Stochastic Flow Models (SFM) used in fluid scheduling. To this end, a classic problem for optimally allocating a resource to multiple competing user queues is considered in the DES context and placed in the framework of SFMs. Infinitesimal Perturbation Analysis (IPA) is used to calculate the gradient estimates for the average holding cost of this system with respect to resource allocation parameters. The monotonicity property of these estimates allows us to prove the optimality of a well-known rule called the "c - mu-rule" under non-idling policies. Furthermore, nonlinear cost functions are considered, yielding simple distribution-free cost sensitivity estimates. Next, we take the first step in using IPA for optimally calculating timeout thresholds in SHS. A Transmission Control Protocol (TCP) communication link is used to examine the effectiveness of SHS and IPA in calculating derivative estimates of a goodput objective with respect to a timeout parameter. The analysis is also extended to the case of multinode communications. Our results reveal a great potential in using IPA to control delay thresholds and motivate more investigations in future. Finally, we propose a general framework for analysis and on-line optimization of SHS which facilitates the use of IPA. In doing so, we modify the previous structure of a Stochastic Hybrid Automaton (SHA) and show that every transition is associated with an explicit event which is defined through a "guard function." This enables us to uniformly treat all events observed on the sample path of the SHS. As a result, a unifying matrix notation for IPA equations is developed which eliminates the need for the case-by-case analysis of event classes as usually done in prior works involving IPA for SHS.
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Neugebauer, Christoph Johannes. "Perturbation theory analysis of non-equilibrium lattice models with spatial heterogeneity." Thesis, University of Cambridge, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.611122.
Повний текст джерелаAshokkumar, C. R. "Eigenvalue/eigenvector perturbation for time response analysis of linear uncertain systems /." The Ohio State University, 1994. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487858417983696.
Повний текст джерелаDE, SANTI FRANCESCA. "Perturbation dynamics in laminar and turbulent flows. Initial value problem analysis." Doctoral thesis, Politecnico di Torino, 2015. http://hdl.handle.net/11583/2613156.
Повний текст джерелаDavoren, Elmarie. "A metabolomics study of selected perturbations of normal human metabolism / Elmarie Davoren." Thesis, North-West University, 2010. http://hdl.handle.net/10394/4219.
Повний текст джерелаThesis (M.Sc. (Biochemistry))--North-West University, Potchefstroom Campus, 2010.