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Rudkin, Aaron. "Frame Analysis of Canadian Copyright Reform 2008-2012: From "Made-in-Canada" to a "Balanced Solution"." Thesis, Université d'Ottawa / University of Ottawa, 2014. http://hdl.handle.net/10393/31601.
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From 2008-2012, the Harper government engaged in an effort to reform Canada's copyright legislation. This thesis uses a frame analysis approach to identify two distinct frames advanced by the government during this reform. 2008's Bill C-61 was unsuccessfully framed as a "Made-in-Canada" bill in order to combat opposition claims that American pressure unduly influenced the policy process. Following the failure of this bill, the government embarked on a public consultation on copyright. Although the government did not substantively modify subsequent reform bills, it was able to leverage the consultation process and Supreme Court of Canada jurisprudence to lend legitimacy to its new frame of the reform as a "balanced approach", build a coalition of support, and mitigate opposition. The thesis' analysis supports key conclusions of existing framing literature and creates a space for the role of ideas in the study of copyright reform in Canada.
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Manojlovic, Irena [Verfasser], and Walter [Akademischer Betreuer] Sekundo. "Entwicklung der Hornhautendothelzelldichte (ECD)in der frühen postoperativen Phase nach Kataraktchirurgie in Abhängigkeit von der Verwendung einer hydroxypropylmethylcellulose-haltigen viskoelastischen Substanz versus Balanced Salt Solution während der Intraokularlinsen-Implantation / Irena Manojlovic. Betreuer: Walter Sekundo." Marburg : Philipps-Universität Marburg, 2015. http://d-nb.info/1066815879/34.
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Martin, Xavier. "Modélisation d'écoulements fluides en milieu encombré d'obstacles." Thesis, Aix-Marseille, 2015. http://www.theses.fr/2015AIXM4759/document.
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On s'intéresse dans ce document à la modélisation d'écoulements compressibles en conduite unidimensionnelle (1D) à section variable et dans des domaines bi ou tridimensionnelles encombrés d'obstacles. Le travail est motivé par la modélisation d'écoulements dans les circuits de refroidissement de réacteurs à eau pressurisée (REP). Ainsi ce travail a pour objectif de proposer une nouvelle formulation pour de tels écoulements. L'idée de base consiste a utiliser une formulation intégrale sur la base des équations aux dérivées partielles. Le système de lois de conservation associé aux équations d'Euler (masse, dynamique et énergie) est examiné.Le premier chapitre examine le cas de conduite 1D à section continue ou discontinue. La formulation intégrale est présentée et les résultats numériques sont comparés avec (i) l'approche Well-Balanced et (ii) la solution de référence obtenue sur maillage très fin.Les second et troisième chapitres examinent la modélisation d'écoulements compressibles dans des domaines contenant de nombreux tubes. La formulation intégrale est donnée, et les schémas numériques présentés, afin de gérer les interfaces fluide/fluide et les parois. Les schémas peuvent être explicites (chapitre 2), ou implicites (chapitre 3). Quelques cas tests analytiques sont présentés. On se concentre sur l'écoulement d'un fluide abordant une zone de tubes alignés de petite taille. Ici encore, la comparaison est faite avec la référence fluide; les résultats sont également comparés avec ceux issus de l'approche équilibre classique, et ceux associés à la formulation intégrale unidimensionnelle présentée dans le premier chapitre<br>This document focuses on the modeling of compressible flows in one-dimensional (1D) pipes with variable cross-section, and in two or three-dimensional domains containing many small obstacles. The basic motivation is urged by the modeling of flows in the coolant circuit of pressurised water reactors (PWR). Thus this work aims at providing a new formulation for such a variety of flows. The basic idea consists in using an integral approach that is applied to the governing set of partial differential equations. Here the keystone is the conservative Euler set of equations, including mass, momentum and energy balance for any equation of state.Hence, the first chapter investigates the case of one-dimensional pipes with continuous or discontinuous cross-section. Once the 1D+ integral formulation has been presented, numerical results are compared with : (i) the classical Well-Balanced (WB) approach, and (ii) the reference solution obtained with a multi-dimensional code with huge mesh refinement.The second and third chapters provide some new insight on the numerical modeling of compressible flows in domains obstructed with many tubes. The integral formulation is derived, and numerical schemes are detailed, in order to handle fluid/fluid interfaces and wall boundaries. Schemes may be explicit (chapter 2), or implicit (chapter 3). A few analytic test cases are investigated. Focus is made on the flow incoming a region containing many tiny and aligned tubes. Here again, a comparison with the reference "fluid" solution is achieved; results are also compared with those arising from the WB approach, and with those coming from the 1D+ integral approach proposed in the first chapter
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Goodson, Michael John. "Stochastic solution of multi-dimensional population balances." Thesis, University of Cambridge, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.611934.
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Adam, Catherine. "Molecular balances for measuring non-covalent interactions in solution." Thesis, University of Edinburgh, 2015. http://hdl.handle.net/1842/16466.
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Non-covalent interactions in solution are subject to modulation by surrounding solvent molecules. This thesis presents two experimental molecular balances that have been used to quantify solvent effects on non-covalent interactions, including electrostatic and dispersion interactions. The first chapter introduces literature where non-covalent interactions have been studied in a range of solvents, particularly those where the effects of aqueous or fluorous solvents have been investigated. These solvents are of particular interest as they both invoke solvophobic effects on organic molecules, but have differing chemical and physical properties. The second chapter describes the adaptation of the Wilcox molecular torsion balance to study interactions between organic and fluorinated carbon chains in a range of solvents. Solvent cohesion was found to be the principle force driving both the alkyl and fluorous chains together in aqueous solvents, where no contribution to the interaction energy arising from dispersion forces could be detected. In fluorous and polar organic solvents evidence was found for weak favourable dispersion interactions between the alkyl chains. In contrast dispersion forces between the chains were found to be disrupted by competitive van der Waals interactions with surrounding solvent molecules in apolar organic solvents. Association of the fluorous chains was found to be solely driven by solvent cohesion. The final chapter describes the design and synthesis of a novel synthetic molecular-balance framework and describes its application to simultaneously measure solvent and substituent effects on the position of conformational equilibria. Despite the simplicity of the model system, surprisingly complicated behaviour emerged from the interplay of conformational, intramolecular and solvent effects. Nonetheless, a large data set of experimental equilibrium constants was analysed using a simple solvent model, which was able to account for both the intuitive and more unusual patterns observed. A means of dissecting electrostatic and solvent effects to reveal pseudo gas-phase behaviour has resulted from the analysis of experimental data obtained in many solvents.
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Kirksey, James Frederick. "Improvement of harmonic balance solution routines for nonlinear systems." Thesis, Georgia Institute of Technology, 1988. http://hdl.handle.net/1853/16480.
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Dalal, Abdulsalam Elmabruk Daw. "Shadow Wave Solutions for Some Balance Law Systems." Phd thesis, Univerzitet u Novom Sadu, Prirodno-matematički fakultet u Novom Sadu, 2017. https://www.cris.uns.ac.rs/record.jsf?recordId=104976&source=NDLTD&language=en.
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In the first part, the pressureless gas dynamic system with source (body force) is examined and solved by using Shadow Waves. The source represents gravity and Shadow Wave solution (containing the delta function) shows acceleration (contrary to shocks, for example). In the second part, one will nd numerical calculations that conrms the above results.<br>Rad je posvecen analizi modela gasa bez pritiska uz dodatak izvora. Model je resen koriscenjem senka talasa. U ovom slucaju, izvor predstavlja uticaj gravitacije na cestice u modelu. Za razliku od udarnih talasa, talasi senke koje sadrze delta funkciju, krecu se ubrzano pod gravitacionim uticajem. U drugom delu rada su naprevljeni numericki eksperimenti koji potvrdjuju teoijske rezultate.
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Nicmanis, Mark. "Finite element methods for the solution of population balance equations." Thesis, University of Cambridge, 1998. https://www.repository.cam.ac.uk/handle/1810/275276.
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Cohen, Mark D. Seinfeld John H. Flagan Richard C. "Studies of concentrated electrolyte solutions using the electrodynamic balance /." Diss., Pasadena, Calif. : California Institute of Technology, 1987. http://resolver.caltech.edu/CaltechETD:etd-03202008-105002.
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Obrigkeit, Darren Donald 1974. "Numerical solution of multicomponent population balance systems with applications to particulate processes." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/31099.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 2001.<br>"June 2001."<br>Includes bibliographical references.<br>Population balances describe a wide variety of processes in the chemical industry and environment ranging from crystallization to atmospheric aerosols, yet the dynamics of these processes are poorly understood. A number of different mechanisms, including growth, nucleation, coagulation, and fragmentation typically drive the dynamics of population balance systems. Measurement methods are not capable of collecting data at resolutions which can explain the interactions of these processes. In order to better understand particle formation mechanisms, numerical solutions could be employed, however current numerical solutions are generally restricted to a either a limited selection of growth laws or a limited solution range. This lack of modeling ability precludes the accurate and/or fast solution of the entire class of problems involving simultaneous nucleation and growth. Using insights into the numerical stability limits of the governing equations for growth, it is possible to develop new methods which reduce solution times while expanding the solution range to include many orders of magnitude in particle size. Rigorous derivation of the representations and governing equations is presented for both single and multi-component population balance systems involving growth, coagulation, fragmentation, and nucleation sources. A survey of the representations used in numerical implementations is followed by an analysis of model complexity as new components are added. The numerical implementation of a split composition distribution method for multicomponent systems is presented, and the solution is verified against analytical results. Numerical stability requirements under varying growth rate laws are used to develop new scaling methods which enable the description of particles over many orders of magnitude in size. Numerous examples are presented to illustrate the utility of these methods and to familiarize the reader with the development and manipulations of the representations, governing equations, and numerical implementations of population balance systems.<br>by Darren Donald Obrigkeit.<br>Ph.D.
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Attarakih, Menwer. "Solution methodologies for the population balance equations describing the hydrodynamics of liquid-liquid extraction contactors." [S.l. : s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=971873631.
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Bartsch, Clemens [Verfasser]. "A Coupled Stochastic-Deterministic Method for the Numerical Solution of Population Balance Systems / Clemens Bartsch." Berlin : Freie Universität Berlin, 2018. http://d-nb.info/1169832105/34.
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Hartman, Bakken Bradley. "Vertebrate solutions to the osmoregulatory quandary posed by nectarivory." Laramie, Wyo. : University of Wyoming, 2008. http://proquest.umi.com/pqdweb?did=1663059741&sid=1&Fmt=2&clientId=18949&RQT=309&VName=PQD.
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Tahri, Yousra. "Vers une meilleure compréhension de la cristallisation en solution de polymorphes : étude expérimentale et modélisation par bilan de population et par équations cinétiques." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSE1159/document.
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La règle des phases d'Ostwald classiquement utilisée pour justifier la cristallisation d'un système polymorphique, stipule que la phase métastable apparait en premier puis subit une transition polymorphique vers la phase stable. Les modèles classiques, qui ne considèrent que la nucléation et la croissance, ne permettent pas de refléter l'avantage cinétique de la phase métastable formulé par la règle d'Ostwald. Cette étude propose d'étudier et de mieux comprendre la cristallisation d'un système polymorphe en prenant en compte le mécanisme de mûrissement d'Ostwald, habituellement négligé. Un produit modèle, l'acide L-Glutamique, est choisi pour l'étude expérimentale menée en milieu agité et stagnant. Deux modèles, l'un basé sur les bilans de population, l'autre basé sur les équations cinétiques, sont développés et qualitativement comparés pour simuler le comportement expérimental des phases polymorphes. Alors que le modèle de bilan de population s'avère limité, le modèle des équations cinétiques a permis de souligner l'effet du mécanisme de mûrissement sur la compétition entre les phases polymorphes et de valider, ainsi, une nouvelle explication pour la règle des phases d'Ostwald<br>The Ostwald rule of stages is conventionally used to explain the crystallization behavior of a polymorphic system. It states that the metastable phase first appears and undergoes a polymorphic transition toward the stable phase, in a second step. The Classical models, which only consider nucleation and growth, fail to reflect the kinetic advantage of the metastable phase formulated by Ostwald’s rule. Hence, this work intends to study and better understand the crystallization of a polymorphic system, taking into account the Ostwald ripening mechanism, usually neglected. A model compound, L-Glutamic acid, is chosen for the experimental study in agitated and stagnant conditions. Two numerical models, one based on the population balance equation and the other based on the kinetic equations, are developed to simulate the behavior of that polymorphic system, observed experimentally. A qualitative comparison between these two models is proposed. The model that relates the population balance equation does not permit correct implementation of all the mechanisms. Conversely, the model based on the kinetic equations highlights the effect of the ripening mechanism on the competition between the two polymorphic phases and allows us to propose a new explanation of the Ostwald rule of stages
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Graham, Gary Thomas. "The effect of nutrient solution ozonation on nutrient balance and lettuce production in a recirculating hydroponic system." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/MQ61898.pdf.
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Ayzac, Virgile. "Engineering new urea-based supramolecular polymers for the charaterization of weak interactions in solution : the supramolecular balance." Electronic Thesis or Diss., Paris 6, 2016. http://www.theses.fr/2016PA066748.
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De nouvelles molécules de bis-urée contenant une fonction ester et ayant la capacité de s’auto-assembler en solution ont été synthétisées. Ces bis-urées ester forment deux types d’assemblages : un filament hélicoïdal et un double filament hélicoïdal. Une transition coopérative entre les deux structures est observée à une température T**. La structure de ces assemblages a été étudiée à l’aide d’une combinaison de FTIR, SANS, CD et modélisation moléculaire. Ce nouveau design permet un accès simplifié à des structures chirales qui ont été utilisées dans le contexte de trois projets différents. (1) Dans le contexte de l’amplification de chiralité, l’effet « majority rules » que présente les bis-urées ester a été étudié de façon à déterminer une relation structure-propriété. (2) Certaines bis-urées ester présentent toutes les propriétés nécessaires à leur utilisation en tant que balance supramoléculaire pour la mesure d’interactions faibles en solution. Nous avons utilisé ce système pour mesurer des interactions halogène···halogène dans des solvants de faible polarité. A notre connaissance, ces dernières n’avaient jamais été observées en solution. (3) Dans le cas de quelques bis-urées ester, un troisième type d’assemblage est observé à plus basse température qui est caractérisé par la formation de liaisons hydrogène entre les groupements urée et ester. De manière surprenante, la réorganisation de ces liaisons hydrogène pendant le chauffage est responsable d’une augmentation de la viscosité. Cette propriété fait de ces composés de potentiels additifs thermoépaississants<br>New self-assembling bis-urea molecules bearing an ester moiety have been synthesized and their properties studied. These ester bis-ureas display two new assemblies: a helical filament and a double helical filament. A cooperative transition is observed between the two structures at a temperature T**. The structure of these assemblies was studied using a combination of FTIR, SANS, CD and molecular modeling. This new design allows an easy access to chiral bis-ureas that were used in the context of three different projects. (1) In the context of chirality amplification, the majority rules effect in ester bis-ureas was studied in order to determine a structure-property relationship. (2) Some ester bis-ureas presented all the necessary properties for their use as a supramolecular balance designed to measure weak interactions in solution. We used this system to measure halogen···halogen interactions in low polarity solvents as those were, to our knowledge, never observed in solution. (3) With specific ester bis-ureas, a third type of assembly was observed at lower temperature that is characterized by the formation of hydrogen bonds between urea and ester moieties. Surprisingly, the reorganization of these hydrogen bonds during heating is responsible for an increase in viscosity. This property allows these compounds to be potential thermothickening additives
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Dhliwayo, Evelyn Chengetanai. "Problem solving in chemical engineering : a study of the solution of mass balance problems by second year students." Master's thesis, University of Cape Town, 2002. http://hdl.handle.net/11427/5376.
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Nourozi, Behrouz. "Sustainable building ventilation solutions with heat recovery from waste heat." Licentiate thesis, KTH, Hållbara byggnader, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-256567.
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The energy used by building sector accounts for approximately 40% of the total energy usage. In residential buildings, 30-60% of this energy is used for space heating which is mainly wasted by transmission heat losses. A share of 20-30% is lost by the discarded residential wastewater and the rest is devoted to ventilation heat loss. The main objective of this work was to evaluate the thermal potential of residential wastewater for improving the performance of mechanical ventilation with heat recovery (MVHR) systems during the coldest periods of year. The recovered heat from wastewater was used to preheat the incoming cold outdoor air to the MVHR in order to avoid frost formation on the heat exchanger surface. Dynamic simulations using TRNSYS were used to evaluate the performance of the suggested air preheating systems as well as the impact of air preheating on the entire system. Temperature control systems were suggested based on the identified frost thresholds in order to optimally use the limited thermal capacity of wastewater and maintain high temperature efficiency of MVHR. Two configurations of air preheating systems with temperature stratified and unstratified tanks were designed and compared. A life cycle cost analysis further investigated the cost effectiveness of the studied systems. The results obtained by this research work indicated that residential wastewater had the sufficient thermal potential to reduce the defrosting need of MVHR systems (equipped with a plate heat exchanger) in central Swedish cities to 25%. For colder regions in northern Sweden, the defrosting time was decreased by 50%. The temperature control systems could assure MVHR temperature efficiencies of more than 80% for most of the heating season while frosting period was minimized. LCC analysis revealed that wastewater air preheating systems equipped with temperature stratified and unstratified storage tanks could pay off their costs in 17 and 8 years, respectively.<br><p>QC 20190830</p>
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Mantri, Yogiraj Verfasser], Sebastian [Akademischer Betreuer] Noelle, and Michael [Akademischer Betreuer] [Herty. "Computing near-equilibrium solutions for hyperbolic balance laws on networks / Yogiraj Mantri ; Sebastian Noelle, Michael Herty." Aachen : Universitätsbibliothek der RWTH Aachen, 2021. http://d-nb.info/1228433038/34.
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Maach, Fatna. "Existence pour des systèmes de réaction-diffusion ou quasi linéaires avec loi de balance." Nancy 1, 1994. http://www.theses.fr/1994NAN10121.
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Notre étude concerne des problèmes d'existence (ou de non-existence) pour des systèmes de réaction-diffusion elliptiques quasi linéaires présentant deux propriétés essentielles et fréquentes dans les applications, à savoir: 1) les solutions (éventuelles) sont positives; 2) la masse totale des composants est a priori contrôlée: ceci correspond à une propriété structurelle des termes non linéaires, par exemple que leur somme est négative ou nulle. Pour les systèmes semi-linéaires deux fois deux, c'est-à-dire lorsque les termes non linéaires sont indépendants des gradients et dans le cas ou l'un des composants est de plus a priori contrôlé, nous faisons une étude complète. Nous analysons en particulier l'influence des données au bord relativement à l'existence ou la non-existence des solutions. Nous montrons ainsi, moyennant certaines hypothèses, que pour la plupart des combinaisons de données au bord, on a existence. Des résultats négatifs sont donnés pour les autres types de données au bord. Quand les termes non linéaires dépendent des gradients et quand cette dépendance est sous-quadratique, nous obtenons l'existence de solutions classiques. Nous donnons également un résultat d'existence lorsque les données sont très peu régulières. Nous étudions enfin le cas de croissance quadratique ou sur-quadratique et nous montrons l'existence de solutions classiques si les operateurs de diffusions sont proportionnels
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Favre, Éric. "Modélisation de l'équilibre de sorption et du transfert de matière dans des membranes à base de polydiméthylsiloxane : application à l'extraction d'alcanols de solutions aqueuses par pervaporation." Vandoeuvre-les-Nancy, INPL, 1994. http://docnum.univ-lorraine.fr/public/INPL_T_1994_FAVRE_E.pdf.
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Le but de ce travail est d'étudier l'extraction de composés organiques de solutions aqueuses par pervaporation sous l'angle du transfert de matière dans la membrane; l'équilibre de sorption et la diffusion de l'eau et d'une série d'alcanols (éthanol à pentanols) dans le polydimethylsiloxane (PDMS) ont été étudiés. La théorie de Flory-Huggins classique ne permet pas de décrire correctement les isothermes de sorption obtenus; une analyse des données d'équilibre, basée sur un critère thermodynamique (Zimm & Lundberg), montre que les molécules d'alcanols ont une tendance à l'autoassociation dans le PDMS (formation de clusters). Les résultats sont correctement décrits par une nouvelle approche mécanistique, postulant l'existence d'affinités élémentaires entre les molécules de solvant et la matrice polymère d'une part, les molécules congénères d'autre part; le modèle conduit à une équation d'équilibre contenant deux paramètres ajustables qui permet la description correcte de nombreux systèmes binaires dans les polymères. La diffusion d'un perméant unique dans le PDMS a été étudiée par la technique de perméation de vapeur; la tendance à la décroissance des coefficients de diffusion avec la fraction volumique en pénétrant correspond qualitativement à l'ordre de tendance à la formation de clusters, dégagé de l'étude de sorption. Dans le dernier chapitre, l'influence de la concentration en alcool et de la température de la charge sur les flux partiels de pervaporation est présentée
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Guglielmo, Thomas P. "Comparative international air cargo solutions: the pathway to a resilient, adaptable, balanced and sustainable secure global air cargo supply chain." Thesis, Monterey, California: Naval Postgraduate School, 2013. http://hdl.handle.net/10945/38939.
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CHDS State/Local<br>A substantial challenge to reducing security gaps in the international air cargo supply chain is the lack of a method of evaluating existing levels of risk based upon points of origin, points of departure and cargo and aircraft type. This is particularly challenging since the current United States air cargo security protocol requires the 100 percent screening of all air cargo without objectively analyzing or evaluating the risk posed by the air cargo. This thesis proposes a risk-based intelligence driven approach to identify and mitigate the threat of the successful introduction of an improvised explosive device into the international air cargo supply chain. The primary thrust of this research effort is to conduct a comparative analysis of the United States international air cargo policies and the European Unions international air cargo policies as a means of evaluating and proposing a risk based intelligence driven international air cargo policy that capitalizes on the strengths of United States and European Unions systems.
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Di, Marcantonio Miriam [Verfasser], and Gerd [Akademischer Betreuer] Bacher. "Modification of charge balance in light emitting electrochemical cells for efficient solution-based devices / Miriam Di Marcantonio ; Betreuer: Gerd Bacher." Duisburg, 2020. http://d-nb.info/1221061844/34.
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van, Heyningen Jan Pieter. "Finding the Balance Between Human Activity and Nature in the Development Debate : -Analyzing interpretations of the ‘problem-solution’ via a Genealogical & Archaeological method -." Thesis, Mälardalen University, School of Sustainable Development of Society and Technology, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-5627.
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<p><em>[This thesis deals with alternate understandings of the relational balance between human activity and global eco-systems. This general understanding shall be conveyed as the ‘problem’ and ‘problem-solution’ for the reason of abstraction from conceptual limitation. However, also capable of mutation and metamorphosis in terms of meaning, the ‘problem’ concept retains in essence the understanding of imbalance between human activity and the global eco-system. Via this tool, the thesis journeys on through various interpretations of the ‘problem’, from a more theoretical set to more practical interpretations with an ‘operationalization’ of one such interpretation at the business level. Simultaneously, the thesis makes use of a Genealogical and Archaeological method of analysis. Therefore, the thesis does not attest to any chronological master narrative, where one event necessarily follows on from another. This thesis seeks to reject that idea, the purpose of which is both to keep a distance and merge with the discourse itself, and to reveal the emergence of three ‘dominant’ power structures of the interpretation of the ‘problem’. In so doing the author is able to reveal several interpretations, reinterpretations of the ‘problem’, as well as the effect lesser power structures have on the various dominant power structures throughout instances in time. Furthermore, this method is able to incorporate a grand scale perspective on the ‘problem’ idea, which serves as an excellent base from which to assess, analyze and reveal assumptions, gaps and contradictions of the various power structures. Consequently the thesis is able to provide calculated solutions on a theoretical level that does not remain one-dimensional but multi-dimensional.] </em></p>
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Larsson, Niklas, and Josefsson Fredrik Ågren. "A study of slow denial of service mitigation tools and solutions deployed in the cloud." Thesis, Linköpings universitet, Institutionen för datavetenskap, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-157721.
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Slow rate Denial of Service (DoS) attacks have been shown to be a very effective way of attacking vulnerable servers while using few resources. This thesis investigates the effectiveness of mitigation tools used for protection against slow DoS attacks, specifically slowheader and slow body. Finally, we propose a service that cloud providers could implement to ensure better protection against slow rate DoS attacks. The tools studied in this thesis are, a Web Application firewall, a reverse proxy using an event-based architecture and Amazon’s Elastic Load Balancing. To gather data a realistic HTTP load script was built that simulated load on the server while using probe requests to gather response time data from the server. The script recorded the impact the attacks had for each server configuration.The results show that it’s hard to protect against slow rate DoS attacks while only using firewalls or load balancers. We found that using a reverse proxy with an event-based architecture was the best way to protect against slow rate DoS attacks and that such a service would allow the customer to use their server of choice while also being protected.
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Vigué, Pierre. "Solutions périodiques et quasi-périodiques de systèmes dynamiques d'ordre entier ou fractionnaire : applications à la corde frottée." Thesis, Aix-Marseille, 2017. http://www.theses.fr/2017AIXM0306/document.
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L'étude par continuation des solutions périodiques et quasi-périodiques est appliquée à plusieurs modèles issus du violon. La continuation pour un modèle à un degré de liberté avec friction régularisée permet de montrer la préservation, par rapport à la friction de Coulomb, des bifurcations de cycle limite (une vitesse maximale et une force minimale permettant le mouvement de Helmholtz) et de propriétés globales de la branche de solution (croissance de l'amplitude avec la vitesse, décroissance de la fréquence avec la force normale). L'équilibrage harmonique est évalué sur la friction régularisée et a des propriétés de convergence intéressantes (erreur faible, monotone, à décroissance rapide). La continuation sur un modèle à deux modes donne accès aux solutions de registres supérieurs, dont la stabilité coïncide avec l'expérience. La valeur retenue pour l'inharmonicité peut modifier fortement le diagramme de bifurcation. Une nouvelle méthode de continuation des solutions quasi-périodiques est proposée. Elle associe l'EH étendu à deux pulsations avec la Méthode Asymptotique Numérique. Une attention particulière est portée à la rapidité des calculs, face à la croissance rapide de la taille des systèmes à inverser. Un modèle de friction prenant en compte la température au point de contact est reformulé à l'aide d'une dérivée fractionnaire. Nous proposons une méthode de continuation de solutions périodiques de systèmes contenant des dérivées ou intégrales fractionnaires. Nous établissons une condition suffisante pour que les cycles asymptotiques du cadre causal (Caputo) soient solutions du cadre que nous avons choisi<br>The continuation of periodic and quasi-periodic solutions is performed on several models derived from the violin. The continuation for a one degree-of-freedom model with a regularized friction shows, compared with Coulomb friction, the persistence of limit cycle bifurcations (a maximum bow speed and a minimum normal force allowing Helmholtz motion) and of global properties of the solution branch (increase of amplitude with respect to the bow speed, decrease of frequency with respect to the normal force). The Harmonic Balance Method is assessed on this regularized friction system and shows interesting convergence properties (the error is low, monotone and rapidly decreasing). For two modes the continuation shows higher register solutions with a plausible stability. A stronger inharmonicity can greatly modify the bifurcation diagram. A new method is proposed for the continuation of quasi-periodic solutions. It couples a two-pulsations HBM with the Asymptotic Numerical Method. We have taken great care to deal efficiently with large systems of unknowns. A model of friction that takes into account temperature of the contact zone is reformulated with a fractional derivative. We then propose a method of continuation of periodic solutions for differential systems that contain fractional operators. Their definition is usually restricted to causal solutions, which prevents the existence of periodic solutions. Having chosen a specific definition of fractional operators to avoid this issue we establish a sufficient condition on asymptotically attractive cycles in the causal framework to be solutions of our framework
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Ali, Qasim. "Contribution to the mathematical modeling of immune response." Phd thesis, Ecole Nationale Supérieure des Mines de Saint-Etienne, 2013. http://tel.archives-ouvertes.fr/tel-00905603.
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The early steps of activation are crucial in deciding the fate of T-cells leading to the proliferation. These steps strongly depend on the initial conditions, especially the avidity of the T-cell receptor for the specific ligand and the concentration of this ligand. The recognition induces a rapid decrease of membrane TCR-CD3 complexes inside the T-cell, then the up-regulation of CD25 and then CD25-IL2 binding which down-regulates into the T-cell. This process can be monitored by flow cytometry technique. We propose several models based on the level of complexity by using population balance modeling technique to study the dynamics of T-cells population density during the activation process. These models provide us a relation between the population of T-cells with their intracellular and extracellular components. Moreover, the hypotheses are proposed for the activation process of daughter T-cells after proliferation. The corresponding population balance equations (PBEs) include reaction term (i.e. assimilated as growth term) and activation term (i.e. assimilated as nucleation term). Further the PBEs are solved by newly developed method that is validated against analytical method wherever possible and various approximate techniques available in the literature.
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Liu, Weiji. "Rôle de la micelle de caséine sur la dénaturation thermique des solutions de protéines de lactosérum et les mécanismes d'encrassement." Electronic Thesis or Diss., Université de Lille (2022-....), 2022. http://www.theses.fr/2022ULILR014.
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Le présent travail est une contribution pour mieux comprendre l’influence des micelles de caseine sur l’encrassement de solutions de protéines sériques. En particulier, des approches expérimentales et numériques ont été réalisées, à des tailles laboratoires et pilotes, pour décrire les phénomènes de dénaturation et mieux cerner le rôle du calcium dans les mécanismes d’encrassement. Tout d'abord, l'effet du ratio massique caséine / lactosérum sur les performances d'encrassement des protéines de lactosérum a été étudié dans un échangeur à Plaques à l'échelle pilote. La masse totale du dépôt d'encrassement chute d’abord de manière significative avec l'augmentation de la concentration en caséine, atteignant un minimum quand le ratio vaut 0,2. Au-delà de cette valeur, la masse de dépôt réaugmente. La chute de la masse du dépôt, pour un ratio ≤ 0,2, ne semble pas être corrélée à la dénaturation thermique du BLG mais plus probablement due à la modification des interactions minérales introduites par la caséine. L'augmentation de la masse de dépôt, pour un ratio ≥ 0,2, semble être liée à une co-précipitation du complexe BLG-caséine qui augmente l'encrassement. Il est suggéré que la présence de caséine micellaire modifie profondément l'équilibre calcique en solution et que la teneur en nanocluster de Ca-P modifie fortement les interactions entre les espèces protéiques et les minéraux (calcium ionique, Ca-P) affectant ainsi la dénaturation des protéines et la précipitation des minéraux. Un nouveau modèle cinétique concernant le dépliement thermique et l'agrégation de BLG a été établi. Ce modèle est en mesure de justifier la rupture de pente dans le diagramme d'Arrhenius et de fournir des informations thermodynamiques détaillées pour les processus de dépliement et d'agrégation. Sur la base de ce modèle, il a été confirmé que le calcium ionique avait un rôle protecteur sur le dépliement thermique du BLG à basse température. En revanche, à des températures plus élevées, le calcium favorise l'agrégation et la formation d'espèces BLG dépliées. Un dispositif d'encrassement à l'échelle laboratoire a été construit et tester avec des protéines de lactosérum en régime laminaire. Un modèle CFD 3D réaliste a été implémenté simulant à la fois les réactions au cœur du fluide et en surface. Les résultats ont montré une relation linéaire entre le facteur pré-exponentiel et la concentration de calcium, ce qui suggère que l'encrassement nécessite qu’une seule molécule de calcium soit associée à une protéine de BLG. Il est confirmé que le calcium est essentiel à l'encrassement avec des effets significatifs à la fois sur les processus de dénaturation thermique et sur la croissance du dépôt. Enfin, l'effet du ratio caséine / lactosérum sur l'encrassement a été étudié avec un dispositif d'encrassement de laboratoire. Les résultats laboratoires montrent que la caséine réduit l’aptitude à l’encrassement comme déterminé précédemment avec l’installation pilote. Cependant, dans ce cas, l'encrassement reste à un niveau faible y compris pour des ratios élevés (jusqu'à 4). La présence de caséines individuelles dans la phase sérique a été considérée comme responsable de cette atténuation de l'encrassement, probablement par leurs activités de type chaperon. Cependant, quand le pH de la solution d'encrassement est fixé à 6,6, il est démontré que la caséine perd son effet d'atténuation de l'encrassement pour des ratios plus élevés. Ce comportement est lié à sa faible capacité de micelle de caséine à contrôler le calcium ionique dans la phase sérique à un pH plus bas, entraînant une concentration plus élevée en calcium facilitant la dénaturation de la BLG et l'accumulation de dépôts. Une quantité plus faible de caséines dissociées dans la phase sérique à pH 6,6 pourrait aussi expliquer l'augmentation de la masse d'encrassement car elles ne sont pas en concentration suffisantes pour remplir des fonctions de type chaperon<br>The present work is a contribution to better understand the influence of casein micelles on the fouling of serum whey protein solutions. In particular, experimental and numerical approaches have been carried out, at laboratory and pilot scales, to describe denaturation phenomena and better understand the role of calcium in fouling mechanisms. First of all, the effect of casein/whey mass ratio on the whey protein fouling performance was investigated in a pilot-scale PHE. The total fouling deposit mass drop significantly with the addition of casein, resulting in a minimum value located at Casein/WPI of 0.2. Exceeding this critical ratio, fouling deposit increased with elevated casein concentrations. The deposit mass drop (Casein/WPI ≤ 0.2) is unlikely to be linked to the thermal denaturation of BLG and is more probably due to the change in mineral interactions introduced by casein. The increased fouling mass (Casein/WPI ≥ 0.2) was attributed to a co-precipitation of BLG-casein complex that enhances the fouling. It is proposed that micellar casein change deeply the calcium balance and the content of CaP nanocluster modifies sharply the interactions which occur between protein species (BLG, caseins) and mineral elements (ionic calcium, Ca-P) thereby affecting the protein denaturation and fouling behavior. A novel kinetic model concerning thermal unfolding and aggregation of BLG was established. This model interprets mathematically the break-slope behavior in the Arrhenius plot and provides detailed thermodynamic information for both unfolding and aggregation processes. Based on this model, it was confirmed that ionic calcium has a protective role on the thermal unfolding of BLG at low temperature. In contrast, at higher temperatures, calcium promotes aggregation and the formation of unfolded BLG species. A bench-scale fouling rig was built to perform whey protein fouling experiments in a laminar regime. A realistic 3D CFD model was achieved to simulate both the bulk and surface reactions. Results showed a linear relationship between the deposition pre-exponential factor and calcium concentration, suggesting the fouling is built in such a pattern that only one calcium ion per BLG molecule is involved. Calcium was confirmed to be essential to fouling growth with significant effects both on the thermal denaturation and deposition processes. Finally, the effect of casein/whey ratio on the whey protein fouling was investigated in the laboratory-scale fouling device. Results revealed a similar effect of casein on fouling mitigation as those found in the pilot plant. However, in this case, the fouling was suppressed and maintained at a low extent even at high Casein/WPI ratios (up to 4). The presence of individual caseins in the serum phase was considered to be responsible for this fouling mitigation probably through their chaperon-like activities. However, when the pH of the fouling solution is set at 6.6, casein is shown to lose its fouling-mitigating effect at higher ratios. This behavior is related to its weak ability of casein micelle to control ionic calcium in the serum phase at lower pH, resulting in higher calcium concentration facilitating BLG denaturation and deposition accumulation. A lower amount of dissociated caseins in the serum phase at pH 6.6 could also explain the increase in fouling mass because they are not in sufficient concentration to perform chaperone-like functions
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Shah, Neelkamal P. "Entropy Maximisation and Queues With or Without Balking. An investigation into the impact of generalised maximum entropy solutions on the study of queues with or without arrival balking and their applications to congestion management in communication networks." Thesis, University of Bradford, 2014. http://hdl.handle.net/10454/7500.
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An investigation into the impact of generalised maximum entropy solutions on the study of queues with or without arrival balking and their applications to congestion management in communication networks
Keywords: Queues, Balking, Maximum Entropy (ME) Principle, Global Balance (GB), Queue Length Distribution (QLD), Generalised Geometric (GGeo), Generalised Exponential (GE), Generalised Discrete Half Normal (GdHN), Congestion Management, Packet Dropping Policy (PDP)
Generalisations to links between discrete least biased (i.e. maximum entropy (ME)) distribution inferences and Markov chains are conjectured towards the performance modelling, analysis and prediction of general, single server queues with or without arrival balking. New ME solutions, namely the generalised discrete Half Normal (GdHN) and truncated GdHN (GdHNT) distributions are characterised, subject to appropriate mean value constraints, for inferences of stationary discrete state probability distributions. Moreover, a closed form global balance (GB) solution is derived for the queue length distribution (QLD) of the M/GE/1/K queue subject to extended Morse balking, characterised by a Poisson prospective arrival process, i.i.d. generalised exponential (GE) service times and finite capacity, K. In this context, based on comprehensive numerical experimentation, the latter GB solution is conjectured to be a special case of the GdHNT ME distribution.
ii
Owing to the appropriate operational properties of the M/GE/1/K queue subject to extended Morse balking, this queueing system is applied as an ME performance model of Internet Protocol (IP)-based communication network nodes featuring static or dynamic packet dropping congestion management schemes. A performance evaluation study in terms of the model’s delay is carried out. Subsequently, the QLD’s of the GE/GE/1/K censored queue subject to extended Morse balking under three different composite batch balking and batch blocking policies are solved via the technique of GB. Following comprehensive numerical experimentation, the latter QLD’s are also conjectured to be special cases of the GdHNT. Limitations of this work and open problems which have arisen are included after the conclusions
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Shah, Neelkamal Paresh. "Entropy maximisation and queues with or without balking : an investigation into the impact of generalised maximum entropy solutions on the study of queues with or without arrival balking and their applications to congestion management in communication networks." Thesis, University of Bradford, 2014. http://hdl.handle.net/10454/7500.
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An investigation into the impact of generalised maximum entropy solutions on the study of queues with or without arrival balking and their applications to congestion management in communication networks Keywords: Queues, Balking, Maximum Entropy (ME) Principle, Global Balance (GB), Queue Length Distribution (QLD), Generalised Geometric (GGeo), Generalised Exponential (GE), Generalised Discrete Half Normal (GdHN), Congestion Management, Packet Dropping Policy (PDP) Generalisations to links between discrete least biased (i.e. maximum entropy (ME)) distribution inferences and Markov chains are conjectured towards the performance modelling, analysis and prediction of general, single server queues with or without arrival balking. New ME solutions, namely the generalised discrete Half Normal (GdHN) and truncated GdHN (GdHNT) distributions are characterised, subject to appropriate mean value constraints, for inferences of stationary discrete state probability distributions. Moreover, a closed form global balance (GB) solution is derived for the queue length distribution (QLD) of the M/GE/1/K queue subject to extended Morse balking, characterised by a Poisson prospective arrival process, i.i.d. generalised exponential (GE) service times and finite capacity, K. In this context, based on comprehensive numerical experimentation, the latter GB solution is conjectured to be a special case of the GdHNT ME distribution. ii Owing to the appropriate operational properties of the M/GE/1/K queue subject to extended Morse balking, this queueing system is applied as an ME performance model of Internet Protocol (IP)-based communication network nodes featuring static or dynamic packet dropping congestion management schemes. A performance evaluation study in terms of the model’s delay is carried out. Subsequently, the QLD’s of the GE/GE/1/K censored queue subject to extended Morse balking under three different composite batch balking and batch blocking policies are solved via the technique of GB. Following comprehensive numerical experimentation, the latter QLD’s are also conjectured to be special cases of the GdHNT. Limitations of this work and open problems which have arisen are included after the conclusions.
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Kovář, Jan. "Metody pro řešení spínaných obvodů." Doctoral thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2012. http://www.nusl.cz/ntk/nusl-233575.
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The dissertation deals with simulations of the DC-DC converters in their basic configurations (Buck, Boost, Buck-boost, Cuk, SEPIC). In the first part of the thesis derivation of transfer functions Line-to-Output (LTO) and Control-To-Output (CTO) can be found. These symbolic responses are derived for three types of basic converters (Buck, Boost, Buck-boost) using well-known average model [1]. Derived expressions are very complicated. For reduction of these expressions symbolic approximation method was used, however the generality is lost. The average model was used to for decreasing the computational effort of analysis of DC-DC converters in the time domain. For these simulations VHDL-AMS language was used. The main topic of the thesis is harmonic balance method, which was adapted to DC-DC converters. Because conditions and assumptions for LTO and CTO functions are very different, harmonic balance method was derived into two variants. For obtaining of LTO response, duty cycle of switching signal can be considered as constant in time. Spectrum of this signal is simple as follows from well-known sinc function. For obtaining of CTO response PWM modulation must be used. Compared to sinc function spectrum of PWM modulation is richer (contains more combination frequencies). Many types of PWM modulation is described in [31]. For simulation PWM modulation with uniform sampling in two variants (single and double edge) was used. Non-ideal switching of PWM switch was modeled by PWM pulse with defined slew rate. Last section deals with comparison of all derived functions (LTO, CTO, modulation type, defined slew rate) with well-known averaged model.
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Bouaniche, Alexandre. "A hybrid stochastic-sectional method for the simulation of soot particle size distributions Vitiated high karlovitz n-decane/air turbulent flames: scaling laws and micro-mixing modeling analysis A hybrid stochastic/fixed-sectional method for solving the population balance equation." Thesis, Normandie, 2019. http://www.theses.fr/2019NORMIR23.
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Les particules de suie (qui sont un type de particules ultrafines) peuvent être produites et émises dans des conditions de combustion riche. Les secteurs comme les transports (routier et aérien), où l'industrie sont des contributeurs significatifs aux émissions de particules. Celles-ci sont habituellement considérées comme des polluants dans la mesure où leur impact négatif sur la santé a été mesuré. Dans certains cas spécifiques comme la production de nanomatériaux, elles peuvent être synthétisées de manière volontaire. Dans les deux cas, une compréhension précise et une capabilité de prédiction de la distribution de tailles de particules (PSD en anglais) sont nécessaires, pour une meilleure conception des chambres de combustion. Dans cette thèse, une méthode innovante est proposée pour la prédiction de l'évolution de la distribution de tailles de particules (PSD). Elle consiste en une approche hybride composée de particules stochastiques représentant une fonction de densité de probabilité (PDF en anglais) et de sections fixes. L'objectif est de résoudre de manière précise le terme source de croissance/oxydation, en traitant le problème de diffusion numérique rencontré par des méthodes sectionnelles classiques. D'autre part, la méthode proposée est moins coûteuse qu'une méthode de Monte Carlo complète. D'abord, le contexte et les motivations de cette thèse sont expliqués. Les concepts et modèles pour les termes sources physiques de suie sont brièvement résumés. Ensuite, l'équation de bilan de population (PBE en anglais) qui pilote l'évolution de la distribution de tailles de particules (PSD), est présentée, ainsi que les différentes classes de méthodes utilisées pour sa résolution. La nouvelle méthode hybride est introduite. Sa précision et son efficacité sont démontrées sur des cas tests analytiques. Enfin, la méthode est appliquée sur une flamme prémélangée d'éthylène<br>Soot particles (which are one kind of ultra-fine particles) can be produced and emitted in fuel rich combustion conditions. Sectors like road and air transportation, or industry are significant contributors to soot particles emissions. Soot particles are usually considered as a pollutant as their negative impact on health has been assessed. In some specific cases like nanomaterials production, they can be synthesized on purpose. In both cases, accurate understanding and prediction capability of the Particle Size Distribution (PSD) is needed, for a better combustors design. In this thesis, a novel numerical method is proposed to predict the Particle Size Distribution (PSD) evolution. It consists in a hybrid approach featuring stochastic particles representing a Probability Density Function (PDF), and fixed sections. The objective is to solve accurately for the surface growth/oxidation term, mitigating the problem of numerical diffusion encountered in some classical sectional methods. On the other hand, the proposed method is less expensive than a full Monte Carlo method. First, the context and motivation of the thesis are explained. Concepts and models for soot physical source terms are shortly reviewed. Then, the Population Balance Equation (PBE), which drives the evolution of the Particle Size Distribution (PSD), is presented as well as the different classes of numerical methods used for its resolution. Subsequently, the novel hybrid method is introduced. Its accuracy and efficiency are demonstrated on analytical test cases. Finally, the method is applied on a premixed ethylene sooting flame
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Nguyen, Thanh Don. "Impact de la résolution et de la précision de la topographie sur la modélisation de la dynamique d’invasion d’une crue en plaine inondable." Thesis, Toulouse, INPT, 2012. http://www.theses.fr/2012INPT0093/document.
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Nous analysons dans cette thèse différents aspects associés à la modélisation des écoulements à surface libre en eaux peu profondes (Shallow Water). Nous étudions tout d’abord le système d’équations de Saint-Venant à deux dimensions et leur résolution par la méthode numérique des volumes finis, en portant une attention particulière sur les aspects hyperboliques et conservatifs. Ces schémas permettent de traiter les équilibres stationnaires, les interfaces sec/mouillé et aussi de modéliser des écoulements subcritique, transcritique et supercritique. Nous présentons ensuite la théorie de la méthode d’assimilation variationnelle de données adaptée à ce type d’écoulement. Son application au travers des études de sensibilité est longuement discutée dans le cadre de l'hydraulique à surface libre. Après cette partie à caractère théorique, la partie tests commence par une qualification de l’ensemble des méthodes numériques qui sont implémentées dans le code DassFlow, développé à l’Université de Toulouse, principalement à l’IMT mais aussi à l’IMFT. Ce code résout les équations Shallow Water par une méthode de volumes finis et est validé par comparaison avec les solutions analytiques pour des cas tests classiques. Ces mêmes résultats sont comparés avec un autre code d’hydraulique à surface libre aux éléments finis en deux dimensions, Telemac 2D. Une particularité notable du code DassFlow est de permettre l’assimilation variationnelle de données grâce au code adjoint permettant le calcul du gradient de la fonction coût. Ce code adjoint a été obtenu en utilisant l'outil de différentiation automatique Tapenade (Inria). Nous testons ensuite sur un cas réel, hydrauliquement complexe, différentes qualités de Modèles Numériques de Terrain (MNT) et de bathymétrie du lit d’une rivière. Ces informations proviennent soit d’une base de données classique type IGN, soit d’informations LIDAR à très haute résolution. La comparaison des influences respectives de la bathymétrie, du maillage et du type de code utilisé, sur la dynamique d’inondation est menée très finement. Enfin nous réalisons des études cartographiques de sensibilité aux paramètres du modèle sur DassFlow. Ces cartes montrent l’influence respective des différents paramètres ou de la localisation des points de mesure virtuels. Cette localisation optimale de ces points est nécessaire pour une future assimilation de données efficiente<br>We analyze in this thesis various aspects associated with the modeling of free surface flows in shallow water approximation. We first study the system of Saint-Venant equations in two dimensions and its resolution with the numerical finite volumes method, focusing in particular on aspects hyperbolic and conservative. These schemes can process stationary equilibria, wetdry interfaces and model subcritical, transcritical and supercritical flows. After, we present the variational data assimilation method theory fitted to this kind of flow. Its application through sensitivity studies is fully discussed in the context of free surface water. After this theoretical part, we test the qualification of numerical methods implemented in the code Dassflow, developed at the University of Toulouse, mainly at l'IMT, but also at IMFT. This code solves the Shallow Water equations by finite volume method and is validated by comparison with analytical solutions for standard test cases. These results are compared with another hydraulic free surface flow code using finite elements in two dimensions: Telemac2D. A significant feature of the Dassflow code is to allow variational data assimilation using the adjoint method for calculating the cost function gradient. The adjoint code was obtained using the automatic differentiation tool Tapenade (INRIA). Then, the test is carried on a real hydraulically complex case using different qualities of Digital Elevation Models (DEM) and bathymetry of the river bed. This information are provided by either a conventional database types IGN or a very high resolution LIDAR information. The comparison of the respective influences of bathymetry, mesh size, kind of code used on the dynamics of flooding is very finely explored. Finally we perform sensitivity mapping studies on parameters of the Dassflow model. These maps show the respective influence of different parameters and of the location of virtual measurement points. This optimal location of these points is necessary for an efficient data assimilation in the future
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Karkar, Sami. "Méthodes numériques pour les systèmes dynamiques non linéaires : application aux instruments de musique auto-oscillants." Phd thesis, Aix-Marseille Université, 2012. http://tel.archives-ouvertes.fr/tel-00742651.
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Ces travaux s'articulent autour du calcul des solutions périodiques dans les systèmes dynamiques non linéaires, au moyen de méthodes numériques de continuation. La recherche de solutions périodiques se traduit par un problème avec conditions aux limites périodiques, pour lequel nous avons implémenté deux méthodes d'approximation : - Une méthode spectrale dans le domaine fréquentiel : l'équilibrage harmonique d'ordre élevé, qui repose sur une formulation quadratique des équations. Nous proposons en outre une formulation originale permettant d'étendre cette méthode aux cas de non-linéarités non rationnelles. - Une méthode pseudo-spectrale par éléments dans le domaine temporel : la collocation à l'aide fonctions polynômiales par morceaux. Ces méthodes transforment le problème continu en un système d'équations algébriques non linéaires, dont les solutions sont calculées par continuation à l'aide de la méthode asymptotique numérique. L'ensemble de ces outils, intégrés au code de calcul MANLAB et complétés d'une analyse linéaire de stabilité, sont alors utilisés pour l'étude des régimes périodiques d'une classe particulière de systèmes dynamiques non linéaires : les instruments de musique auto-oscillants. Un modèle physique non-régulier de clarinette est étudié en détail : à partir de la branche de solutions statiques et ses bifurcations, on calcule les différentes branches de solutions périodiques, ainsi que leur stabilité et leurs bifurcations. Ce modèle est ensuite adapté au cas du saxophone, pour lequel on intègre une caractérisation acoustique expérimentale, afin de mieux tenir compte de la géométrie complexe de l'instrument. Enfin, nous étudions un modèle physique simplifié de violon, avec une non-régularité liée frottement de Coulomb. Cette dernière application illustre ainsi la polyvalence des outils développés face aux différents types de non-régularité.
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MACÊDO, Hildênio José. "Existência de soluções de equilíbrios tipo Instanton para uma equação de evolução com convolução." Universidade Federal de Campina Grande, 2011. http://dspace.sti.ufcg.edu.br:8080/jspui/handle/riufcg/1242.
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Previous issue date: 2011-05<br>CNPq<br>Na presente dissertação, estudamos a existência e unicidade de solução para o
problema de Cauchy associado a equação de evolução não local (Baixar arquivo para ver a equação). Exibimos um funcional energia, associado a esta equação, e verificamos que ele satisfaz a propriedade de Lyapunov. Além disso, usamos este funcional para mostrar a existência e estabilidade local de uma solução de equilíbrio referida na literatura como instanton.<br>In this work we prove existence and uniqueness of solution for the Cauchy problem
corresponding to nonlocal evolution equation (Download file to see the equation). We exhibit an energy functional associated to this equation, and verify that it satisfies the Lyapunov property. Moreover, use this function to show the existence and local stability of a equilibrium solution reported in the literature as instanton.
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Stauffert, Maxime. "Simulation numérique d'écoulements compressibles complexes par des méthodes de type Lagrange-projection : applications aux équations de Saint-Venant." Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLV045/document.
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On étudie dans le cadre de la thèse une famille de schémas numériques permettant de résoudre les équations de Saint-Venant. Ces schémas utilisent une décomposition d'opérateur de type Lagrange-projection afin de séparer les ondes de gravité et les ondes de transport. Un traitement implicite du système acoustique (relié aux ondes de gravité) permet aux schémas de rester stable avec de grands pas de temps. La correction des flux de pression rend possible l'obtention d'une solution approchée précise quel que soit le régime d'écoulement vis-à-vis du nombre de Froude. Une attention toute particulière est portée sur le traitement du terme source qui permet la prise en compte de l'influence de la topographie. On obtient notamment la propriété dite équilibre permettant de conserver exactement certains états stationnaires, appelés état du "lac au repos". Des versions 1D et 2D sur maillages non-structurés de ces méthodes ont été étudiées et implémentées dans un cadre volumes finis. Enfin, une extension vers des méthodes ordres élevés Galerkin discontinue a été proposée en 1D avec des limiteurs classiques ainsi que combinée avec une boucle MOOD de limitation a posteriori<br>In this thesis we study a family of numerical schemes solving the shallow water equations system. These schemes use a Lagrange-projection like splitting operator technique in order to separate the gravity waves and the transport waves. An implicit-explicit treatment of the acoustic system (linked to the gravity waves) allows the schemes to stay stable with large time step. The correction of the pressure fluxes enables the obtain of a precise approximation solution whatever the regime flow is with respect to the Froude number. A particular attention has been paid over the source term treatment which permits to take the topography into account. We especially obtain the so-called well-balanced property giving the exact conservation of some steady states, namely the "lake at rest" state. 1D and 2D versions of this methods have been studied and implemented in the finite volumes framework. Finally, a high order discontinuous Galerkin extension has been proposed in 1D with classical limiters along with a combined MOOD loop a posteriori limiting strategy
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min-yi, Wu, and 吳旻益. "Study of the Balanced Realization on the solution of SNP Problem." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/01378704014425015675.
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Liu, Pei-Chun, and 劉倍君. "Exploring Project Management Methodology as a Practical Solution for Balanced Scorecard Process." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/06270426338632551204.
Full textAbstract:
碩士<br>長榮大學<br>企業管理學系碩士班<br>97<br>Abstract
Most companies recognize the need to use the balance scorecard (BSC) in order to assess and measure how corporate efforts contribute to overall organizational objectives. By using the project management (PM) methodology in BSC implementation, project managers can understand problem areas as well as improving current projects, which would enhance their abilities to take corrective actions that ensure and maximize successful outcomes from implemention (Muller, 2007). The main purpose of study is to explore all those preceding problems, and success factors of BSC implemented could be solved by PM methodology. It is expected that this integration will help make the BSC a more viable strategy implementation tool (Othman, 2006). The method of literature review is used in this study. By collecting those literatures about executing BSC implementation with respect to the PM methodology is fairly treated and reviewed sequentially. This study results showed that PM has positive impacts on some issues of the BSC, with relation to management of time, cost, quality, or some of them. Nevertheless, some sub-processes in the fields of procurement are sometimes ignored when firm implemented BSC. Therefore, BSC implementation would be effective achieve organization’s strategy objectives if firms consider the whole PM framework in the future. To conclude, the PM methodology spanning all nine knowledge through BSC implementation are beyond tradition. This study also demonstrates the PM methodology would be full of flexibility to provide a practical solution for BSC implementation.
Keyword: Project Management, Balanced Scorecard
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Pillay, Krishnan. "Comparative in vitro analysis of a balanced electrolyte solution versus an unbalanced electrolyte solution, for processing of residual pump blood using cell saver for patients undergoing elective cardiac surgery." Thesis, 2016. http://hdl.handle.net/10321/1735.
Full textAbstract:
Submitted in fulfillment for the degree of Master of Technology, Clinical Technology: Cardiovascular Perfusion, Durban University of Technology, Durban, South Africa, 2016.<br>Introduction:
A large volume of residual haemodilute blood remains in the cardiopulmonary bypass (CPB) circuit after termination of the bypass. It is common practice in many centres to process residual pump blood with an autologus cell salvage system (ACSS), thereby producing a re-suspended red blood cell (RBC) concentrate and attenuating the need for donor blood RBC concentrate. It has also become standard practice to wash donor pack red blood cells (PRBC) before adding it to neonate cardiopulmonary circuits (Swindell et al., 2007). Manufactures of ACSS recommend 0.9% sodium chloride (NaCl) as a wash solution for processing salvaged blood. Previous studies have demonstrated that washing PRBC with normal saline results in acid-base (Huber et al., 2013) and electrolyte derangements (Varghese et al., 2007). Infusion of normal saline in healthy volunteers also results in significant changes in osmolality (Williams et al., 1999). The use of normal saline as a wash solution in processing residual CPB blood requires investigation.
Aims and Objectives:
This was a prospective, quantitative in vitro investigation to analyze and compare the quality of residual pump blood post CPB that had been washed with either an unbalanced electrolyte solution (0.9% normal saline) or a balanced electrolyte solution (Balsol®). Both are crystalloid solutions. The primary objective of the present study was to measure and compare the pH, electrolytes, metabolites, osmolality and strong ion difference (SID) of residual pump blood to the pH, electrolytes, metabolites, osmolality and SID of processed cell saver blood, which was washed with either 0.9% normal saline or Balsol® solution. The secondary objective was to measure and compare protein levels (albumin and total protein) in residual pump blood to protein levels in processed cell saver blood, that is washed with either 0.9% normal saline or Balsol® solution. The final objective was to determine the volume, haematocrit and haemoglobin yield post cell saver processing, from the input volume of residual pump blood when washed with either 0.9% normal saline or Balsol® solution. This was the first study of this nature done in the South African population group.
Methodology:
In this investigation in a series of forty patients (n=40) undergoing elective cardiac surgery with CPB, the first twenty patients were allocated to the NaCl control group (n=20) and the second twenty patients were allocated to the Balsol® interventional group (n=20). The extracorporeal circuit consisted of a standard integral hollow fibre membrane oxygenator and tubing that was primed with 1500-1800 millilitres of balanced crystalloid solution (Balsol®), for both the control group and the interventional group, and addition of 5000 iu heparin. The balanced crystalloid solution (Balsol®) is the approved standard CPB priming solution for all cardiac procedures at Inkosi Albert Luthuli Central Hospital.
This setup was used with the Stockert S5 roller pump heart lung machine. The operations were performed as per protocol with standard non-pulsatile CPB and hypothermia was maintained at 28 – 32 ºC (core) and haemodilution (haematocrit 20 % to 30 %). A standard flow rate of 2.4 L/min/m² was used. Cardio protection consisted of either cold Blood Cardioplegia using the Buckberg 4:1 ratio, being four parts blood to one part cardioplegia (with the 35ml of 20 % Dextrose + 1 gram Magnesium Sulphate added per 500ml), or 20ml/kg cold St Thomas II cardioplegia (with addition of 10ml of 8.5% NaHCO3 + 100mg lignocain per litre). Topical cooling was achieved with ice cold 0.9 % saline. Maintenance fluid used during CPB was Balsol® for both the control and the interventional groups. Calcium, potassium and sodium bicarbonate was administered as required during CPB to correct deficits for both groups. Weaning of CPB was performed after re-warming to a rectal temperature of at least 35 ºC for both study groups.
Immediately on termination of CPB a blood sample was taken from the sampling manifold of the CPB circuit for pre wash analysis. Residual pump blood was then flushed out with one litre of Balsol® solution for both groups and collected into the Medtronic autolog cell saver reservoir to be processed. In the control study group 0.9% NaCl was used as the wash solution and in the interventional study group Balsol® solution was used as the wash solution. After processing of the salvaged blood is complete, a blood sample was taken for post wash analysis. Clinical data recorded for pre and post wash samples included: pH, pCO2, pO2, [K+], [Na+], [Cl-], [Ca2+], lactate, glucose, [HCO3-], TCO2, haematocrit, haemoglobin (GEM 4000® premier™ blood gas analyser) blood volume (Medtronic autolog) and SID (calculated as per equation). Inorganic phosphate, total magnesium, albumin, total protein (Siemens Advia 1800 blood gas analyser) and osmolality (Gonotech osmometer) were also measured.
Results:
There was a highly significant decrease (p < 0.05) within the NaCl group after washing with pCO2 (28.3 ± 2.9 vs. <6.0 ± 0.0), [K+] (4.5 ± 0.5 vs. 1.0 ± 0.7), total magnesium (1.7 ± 0.7 vs. 0.29 ± 0), ionized calcium (1.0 ± 0.09 vs. 0.1 ± 0.03), inorganic phosphate (0.9 ± 0.4 vs. 0.09 ± 0.04) and SID (27.1 ± 2.1 vs. 18.4 ± 2.2). There was a highly significant increase (p < 0.05) within the NaCl group after washing with pH (7.5 ± 0.1 vs. 7.7 ± 0.1), [Na+] (132.9 ± 3.2 vs. 146.3 ± 1.9), [Cl-] (107.8 ± 3.1 vs. 127.4 ± 2.1) and osmolaltity (256.9 ± 38.4 vs. 296.2 ± 57.5).
There were highly significant decrease (p < 0.05) within the Balsol® group after washing with pCO2 (30.15 ± 6.0 vs. 18.9 ± 4.9), [Na+] (134.7 ± 2.2 vs. 125.6 ± 1), [Cl-] (108.8 ± 2.7 vs. 100.2 ± 1.4), ionized calcium (0.9 ± 0.1 vs. 0.02 ± 0.04), inorganic phosphate (0.8 ± 0.2 vs. 0.1 ± 0.024) and osmolality (288.8 ± 20.6 vs. 272.8 ± 19.9). There were highly significant increase (p < 0.05) within the Balsol® group after washing with pH (7.5 ± 0.1 vs. 7.7 ± 0.1), [K+] (4.2 ± 0.4 vs 4.6 ± 0.3). Total magnesium and SID were similar after washing within the Balsol® group. Albumin and total protein revealed similar significant decreases within both groups after washing.
There was a highly significant difference (p < 0.05) in the change between groups after washing in all the variables measured, except for pH, inorganic phosphate, lactate, glucose, albumin, total protein, haematocrit, haemoglobin, and blood volume. Total carbon dioxide and [HCO3-] were not compared because they were incalculable by blood gas analyser in the NaCl group.
Conclusion:
This investigation concluded that the balanced electrolyte solution Balsol® used for washing residual CPB blood results in a re-suspended RBC concentrate, with an osmolality and electrolyte profile that is superior compared to washing residual CPB blood with 0.9% NaCl solution.<br>M
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"Following a "balanced" trajectory from an infeasible point to an optimal linear programming solution with a polynomial-time algorithm." Alfred P. Sloan School of Management, Massachusetts Institute of Technology, 1992, 2003. http://hdl.handle.net/1721.1/2428.
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Mungkasi, Sudi. "A study of well-balanced finite volume methods and refinement indicators for the shallow water equations." Phd thesis, 2012. http://hdl.handle.net/1885/10301.
Full textAbstract:
This thesis studies solutions to the shallow water equations analytically and numerically. The study is separated into three parts. The first part is about well-balanced finite volume methods to solve steady and unsteady state problems. A method is said to be well-balanced if it preserves an unperturbed steady state at the discrete level. We implement hydrostatic reconstructions for the well-balanced methods with respect to the steady state of a lake at rest. Four combinations of quantity reconstructions are tested. Our results indicate an appropriate combination of quantity reconstructions for dealing with steady and unsteady state problems.
The second part presents some new analytical solutions to debris avalanche problems and reviews the implicit Carrier-Greenspan periodic solution for flows on a sloping beach. The analytical solutions to debris avalanche problems are derived using characteristics and a variable transformation technique. The analytical solutions are used as benchmarks to test the performance of numerical solutions. For the Carrier-Greenspan periodic solution, we show that the linear approximation of the Carrier-Greenspan periodic solution may result in large errors in some cases. If an explicit approximation of the Carrier-Greenspan periodic solution is needed, higher order approximations should be considered. We propose second order approximations of the Carrier-Greenspan periodic solution and present a way to get higher order approximations. The third part discusses refinement indicators used in adaptive finite volume methods to detect smooth and nonsmooth regions. In the adaptive finite volume methods, smooth regions are coarsened to reduce the computational costs and nonsmooth regions are refined to get more accurate solutions. We consider the numerical entropy production and weak local residuals as refinement indicators. Regarding the numerical entropy production, our work is the first to implement the numerical entropy production as a refinement indicator into adaptive finite volume methods used to solve the shallow water equations. Regarding weak local residuals, we propose formulations to compute weak local residuals on nonuniform meshes. Our numerical experiments show that both the numerical entropy production and weak local residuals are successful as refinement indicators.
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César, Mariana Ferreira. "A framework for analysing the effectiveness of Fnac´s CRM solution." Master's thesis, 2021. http://hdl.handle.net/10400.14/35037.
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Fnac, as a highly competitive retailer, performs several Customer Relationship Management (CRM) initiatives not only to build a stronger relationship with the customer but also to gain customer knowledge. CRM initiatives can sometimes become hard to quantify. Therefore, this research aimed to build a dashboard of metrics specifically for Fnac to monitor their CRM initiatives performance.
This dissertation includes a Literature Review section, in which CRM was introduced as a profitable strategy to follow, that although used by many companies is still lacking proper measuring tools. Additionally, in this chapter, some measuring frameworks were presented as a solution to build a CRM measuring model for Fnac. In the following section, several methods were chosen to face the challenge proposed. The first was a benchmarking analysis to the main competitors to analyse their current CRM strategy and respective measurement solution. The other method applied was replicating a model previously presented in the Literature Review section adapted for Fnac. As a complement to the last method, a customer survey was performed.
Conclusion and recommendations for each method applied in the analysis were gathered in the last chapter. Based on the benchmarking analysis, a few of the approaches performed by the competitors were suggested as a possible implementation for Fnac. From the model replication and the customer survey, Fnac’s weaknesses and strengths were highlighted.<br>A Fnac, como retalhista altamente competitivo, desempenha iniciativas de Customer Relationship Management (CRM) para, não só, construir um relação mais forte com o cliente mas também conseguir obter conhecimento sobre os segmentos dos consumidores. As iniciativas de CRM podem ser difíceis de quantificar, assim, esta tese teve como objetivo construir uma tabela de métricas especificamente para a Fnac poder monitorizar o desempenho de suas iniciativas de CRM.
Este estudo inclui uma Revisão de Literatura, na qual o CRM foi apresentado como uma estratégia lucrativa, que embora seja utilizada por muitas empresas, ainda carece de ferramentas de medição adequadas. Adicionalmente, ainda neste capítulo, algumas ferramentas de medição foram apresentadas como possíveis soluções para construir um modelo de medição de CRM para Fnac. No capitulo seguinte, vários métodos foram selecionados para resolver o desafio proposto. O primeiro método foi uma análise de benchmarking aos principais concorrentes para analisar sua atual estratégia de CRM e respetiva solução de medição. O outro método aplicado foi a aplicação de um modelo previamente apresentado na seção Revisão da Literatura que foi adaptado para a Fnac. Como complemento ao último método, foi realizada também um questionário aos clientes.
As conclusões e recomendações para cada método usado na análise foram reunidas no último capítulo. Com base na análise de benchmarking, algumas das abordagens referidas pelos concorrentes foram sugeridas para serem implementadas no futuro pela Fnac. A partir da aplicação do modelo e do questionário, os pontos fortes e fracos da Fnac foram destacados.
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Strydom, Petrus Johannes. "Balance sheet management solution: integrating credit, interest and liquidity cost." Thesis, 2018. https://hdl.handle.net/10539/25873.
Full textAbstract:
Degree of Doctor of Philosophy:
A Thesis submitted to the Faculty of Science, University of the Witwatersrand,
Johannesburg, in fulfillment of the requirements for the Doctor of Philosophy.
May 29, 2018<br>This thesis main contribution is the model framework based on the projection of
the banks' balance sheet taking all major nancial risks into account. Real bank
data is used to support this analysis, covering a large range of customer and product
level data across both retail and corporate products. This thesis explicitly explores
the link between retail customers from a deposit, lending activity and performance
and other market driven factors such as liquidity risk premium of cost of funding.
Various optimization techniques are tested, con rming the value of a strategy that
dynamically re-balance the funding pro le of the bank versus a more static approach.
In this thesis, we apply two optimisation frameworks to determine the optimal
wholesale funding mix of a bank, given uncertainty in both credit and liquidity
risk. A stochastic linear programming method is used to nd the optimal strategy
to be maintained across all scenarios. A recursive learning method is developed to
provide the bank with a trading signal to dynamically adjust the wholesale funding
mix as the macroeconomic environment changes. The performance of the two
methodologies is compared in chapter 3. The optimisation target is the net interest
income of the bank. The on-line recursive learning method provides superior results
as this allows the bank to dynamically adjust the funding pro le.
This thesis integrates the sub-components underlying the bank's balance sheet to
facilitate the projection of the net interest income allowing for both liquidity, interest
and credit risk. The sub-components include retail and wholesale loans, retail
and wholesale deposits and bank issued debt instruments. Actual historical data
was obtained from a South African bank to calibrate a model for each of these subcomponents
(discussed in chapters 4-7).<br>MT 2018
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Cohen, Mark Daniel. "Studies of Concentrated Electrolyte Solutions Using the Electrodynamic Balance." Thesis, 1987. https://thesis.library.caltech.edu/1036/4/Cohen_md_1987.pdf.
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<p>An electrodynamic balance has been used to measure the water activity as a function of solute concentration at 20 °C for eleven single-electrolyte aqueous solutions - NaCl, NaBr, KCl, KBr, NH<sub>4</sub>Cl, Na<sub>2</sub>SO<sub>4</sub>, (NH<sub>4</sub>)<sub>2</sub>SO<sub>4</sub>, CaCl<sub>2</sub>, MnCl<sub>2</sub>, MnSO<sub>4</sub> and FeCl<sub>3</sub> - and three mixed-electrolyte aqueous solutions - NaCl-KCl, NaCl-KBr, and NaCl-(NH<sub>4</sub>)<sub>2</sub>SO<sub>4</sub>. The measurements were performed by levitating single, charged, 20-micron diameter droplets of these solutions within the balance and measuring the mass of the particles as a function of the surrounding relative humidity. The deliquescence behavior of the particles was also observed.</p>
<p>Heterogeneous nucleation was inhibited due to the absence of container walls and because the small droplets were less likely than a bulk sample to contain foreign particles. Thus, this technique allowed the thermodynamics of highly concentrated solutions to be studied. For most of the solutions, water activity measurements were made to higher solute concentrations than have previously been reported. At low concentrations, the results were consistent with previously published data. Nucleation theory was used to estimate the surface excess free energy and critical nucleus size from the measured supersaturation at which nucleation occurred.</p>
<p>For the single-electrolyte solutions, the dependence of the solute activity coefficient on concentration was calculated, and the features of this dependence are discussed in relationship to ionic hydration and association. Several semi-empirical electrolyte solution models were tested against the data, and it was found that salt-specific model parameters estimated from low concentration data could not be reliably used to predict the solution behavior at high concentrations. However, with estimated parameters based on the full range of the data, the models were able to represent the experimental data for single-electrolyte solutions to within the uncertainty in the measurements.</p>
<p>Three models of mixed-electrolyte solutions — the Zdanovskii-Stokes-Robinson, Reilly-Wood-Robinson and Pitzer methods — agreed well with the experimental data for the NaCl-KCl and NaCl-KBr systems over the range of concentration that the models could be applied. The mixing rules' predictions were consistent with the experimental observations for the NaCl-(NH<sub>4</sub>)<sub>2</sub>SO<sub>4</sub> particles assuming a small amount of water was retained in the dry state.</p>
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Chang, Yuan, and 張淵. "Global Weak Solutions to the Cauchy Problem ofNonlinear Balance Laws." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/79227012584072387846.
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博士<br>國立中央大學<br>數學研究所<br>96<br>This thesis is divided into two parts. The part I is: Existence and Uniqueness of Lax-Type Solutions to the Riemann Problem of Scalar Balance Law with Singular Source Term,and the part II is: Globally Lipschitz Continuous Solutions to a Class of Quasilinear Wave Equations.
In the part I of the thesis we give a new approach of constructing the generalized entropy solutions to the Riemann problem of scalar nonlinear balance laws. The source term of equation is singular in the sense that it is a product of delta function and a discontinuous function. By re-formulating the source term, we study the corresponding perturbed Riemann problem. The existence and stability of perturbed Riemann solutions is established, and the generalized entropy solutions of Riemann problem are constructed as the limit of corresponding perturbed Riemann solutions. The self-similarity of generalized entropy solutions is also obtained so that Lax''s method can be extended to the scalar nonlinear balance laws with singular source terms.
In the part II of the thesis we investigate the existence of globally Lipschitz continuous solutions to a class of Cauchy problem of quasilinear wave equations. Applying the Lax''s method and generalized Glimm''s method, we construct the approximate solutions of the corresponding perturbed Riemann problem and establish the global existence for the derivatives of solutions. Then, the existence of global Lipschitz continuous solutions can be carried out by showing the weak convergence of residuals for the source term of equation.
Keywords. Conservation laws; Nonlinear balance laws; Riemann problems; Perturbed Riemann problems; Characteristic method; Lax''s method; Quasilinear wave equations; Hyperbolic systems of balance laws; Cauchy problem; Generalized Glimm''s method.
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Lee, Yu-cheng, and 李育誠. "Global Classical Solutions for the 2 × 2 Nonlinear Balance Laws." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/74709341019960714764.
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碩士<br>國立中央大學<br>數學研究所<br>98<br>In this thesis, we consider the Cauchy problem of 2 × 2 nonlinear hyperbolic balance laws whose source terms consist of the integral of unknowns. Such nonlinear balance laws arise in, for instance, the compressible Euler-Poisson equations of gas dynamics in Lagrangian coordinate. We are concerned with the global existence of classical solutions to the Cauchy problem of such differential-integro systems. We extend the results by Ta-tsien Li for quasilinear hyperbolic systems to our nonlinear balance laws. The method in this thesis based on the following three steps: (1) the theory of local classical solutions, (2) uniform a priori estimate, (3) global existence or blow up of classical solutions. We find the transformation so that the 2 × 2 system for the first derivatives of Riemann invariants are de-coupled under this transformation. So, the characteristic method for scalar equations can be applied.
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Chou, Shih-Wei, and 周世偉. "Classical Solution to the Perturbed Riemann Problem of Scalar Nonlinear Balance Law." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/79556876654862577009.
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碩士<br>國立中央大學<br>數學研究所<br>95<br>In this paper we study the global existence of classical solutions to the perturbed Riemann problem of scalar nonlinear balance law. The characteristic method is used to establish the existence of classical perturbed Riemann solutions. Moreover, the generalized solutions of Riemann problem to scalar balance law is obtained by taking the limit of perturbed Riemann solutions. Furthermore, we also obtain the self-similarity of generalized Riemann solutions (rarefaction waves) which enables us to apply Lax''s method to the Riemann problem of scalar nonlinear balance laws.
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Lin, Yu-Min, and 林育民. "Study of the periodic solutions of ball-type automatic balancer systems." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/76743578712128979929.
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碩士<br>國立臺灣大學<br>機械工程學研究所<br>96<br>Many devices have been proposed for the reduction of the rotational vibrations of optical disk drives. Among these vibration-reduction devices, the ball-type automatic balancer is most popular and has been analyzed comprehensively. However, most of the studies on the automatic balancers to date focused on the local dynamical characteristics of the system about the equilibrium positions. In order to have a global analysis of the system, one has to determine the periodic solutions of the system first. The periodic motions of the balls can be classified into two types: oscillatory and rotary periodic motions. Little attention has been paid to the determination of rotary periodic motions of a dynamic system. In this paper, we modify the incremental harmonic balance method such that the rotary periodic motions can be determined efficiently as well as the oscillatory periodic motions. Using this method, we perform global dynamic analysis of the automatic balancer system. We scan the parametric space for possible periodic motions and determine the associated existence regions. The stable regions of the periodic motions are compared with those of the equilibrium positions. Where there exist multiple attractors, the domains of attraction of the attractors in the state space are determined. Under some conditions, the boundary of the basin of attraction of the perfect balancing positions is quite complicated. In this case, the performance of the automatic balancer is sensitive to the initial states of the system.
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Io, Man-meng, and 姚文銘. "Classical Solutions to the Perturbed Riemann Problem of Scalar Resonant Balance Law." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/zm28b2.
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碩士<br>國立中央大學<br>數學研究所<br>96<br>In this paper we study the classical solutions to the perturbed Riemann problem of some scalar nonlinear balance law in resonant case. The equation with source term is equivalent to a 2×2 nonlinear balance laws as described in [6, 7], and it is a resonant system due to the fact that the speeds of waves in the solution to this 2×2 system coincide. The characteristic method in [8] is applied to construct the classical solutions of perturbed Riemann problem. Moreover, we show that, the pointwise limit of classical solutions, which are defined as the
measurable solutions to the corresponding Riemann problem (with singular source) of perturbed Riemann problem, are self-similar as described in [12].
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Tien, Meng-Hsuan, and 田孟軒. "Numerical and Experimental Study of Periodic Solutions of Ball-Type Automatic Balancer Systems." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/76873629505916915843.
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碩士<br>國立臺灣大學<br>機械工程學研究所<br>99<br>Under proper working conditions, a ball-type automatic balancer can adjust the positions of its balls according to the imbalance of the rotor and significantly reduces the rotational vibrations. As a consequence, ball-type automatic balancers are widely applied to rotor systems. However, when the rotational speed is above the natural frequency of the system, the balls may not settle to the perfect balancing positions but keep circulating or oscillating around the disk and result in large vibrations. Moreover the rotary periodic motions can’t be determined by the existing numerical methods used for the detection of periodic solutions. In this study, we employed the modified incremental harmonic balance method to analyze all kind of periodic motions, obtain the existence regions in the η-Ω plane and determine the corresponding stability. Then a comprehensive parametric study was performed and the results were verified experimentally.