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Dissertations / Theses on the topic 'Delay differential equation'
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Gallage, Roshini Samanthi. "Approximation Of Continuously Distributed Delay Differential Equations." OpenSIUC, 2017. https://opensiuc.lib.siu.edu/theses/2196.
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We establish a theorem on the approximation of the solutions of delay differential equations with continuously distributed delay with solutions of delay differential equations with discrete delays. We present numerical simulations of the trajectories of discrete delay differential equations and the dependence of their behavior for various delay amounts. We further simulate continuously distributed delays by considering discrete approximation of the continuous distribution.
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Fontana, Gaia. "Traffic waves and delay differential equations." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2020. http://amslaurea.unibo.it/21211/.
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Questo elaborato si pone l'obiettivo di studiare il problema del traffico, concentrandosi su un modello semplificato in cui i veicoli sono confinati su una circonferenza e la cui velocità è determinata dal modello optimal velocity.
Il discorso si sviluppa su tre capitoli: nel primo viene presentato il modello optimal velocity per il flusso del traffico e si procede a uno studio della stabilità lineare attorno al punto di equilibrio stazionario.
Nel secondo capitolo lo stesso modello viene studiato nel limite termodinamico per un numero infinito di veicoli. Si ricava una soluzione costituita da un'onda di traffico che si propaga in verso opposto al moto delle auto.
Nel terzo e ultimo capitolo il modello viene studiato tramite teoria perturbativa nell'intorno del punto critico, introducendo un potenziale termodinamico e seguendo la teoria di Landau delle transizioni di fase. Vengono infine ricavate le medesime condizioni di stabilità del sistema trovate nel primo capitolo.
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Zhou, Ziqian. "Statistical inference of distributed delay differential equations." Diss., University of Iowa, 2016. https://ir.uiowa.edu/etd/2173.
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In this study, we aim to develop new likelihood based method for estimating parameters of ordinary differential equations (ODEs) / delay differential equations (DDEs) models. Those models are important for modeling dynamical processes that are described in terms of their derivatives and are widely used in many fields of modern science, such as physics, chemistry, biology and social sciences. We use our new approach to study a distributed delay differential equation model, the statistical inference of which has been unexplored, to our knowledge. Estimating a distributed DDE model or ODE model with time varying coefficients results in a large number of parameters. We also apply regularization for efficient estimation of such models. We assess the performance of our new approaches using simulation and applied them to analyzing data from epidemiology and ecology.
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Wang, Yong Tian. "Stochastic differential delay equation with jumps and application to finance." Thesis, Swansea University, 2007. https://cronfa.swan.ac.uk/Record/cronfa43121.
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Olien, Leonard. "Analysis of a delay differential equation model of a neural network." Thesis, McGill University, 1995. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=23927.
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In this thesis I examine a delay differential equation model for an artificial neural network with two neurons. Linear stability analysis is used to determine the stability region of the stationary solutions. They can lose stability through either a pitchfork or a supercritical Hopf bifurcation. It is shown that, for appropriate parameter values, an interaction takes place between the pitchfork and Hopf bifurcations. Conditions are found under which the set of initial conditions that converge to a stable stationary solution is open and dense in the function space. Analytic results are illustrated with numerical simulations.
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Dvořáková, Stanislava. "The Qualitative and Numerical Analysis of Nonlinear Delay Differential Equations." Doctoral thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2011. http://www.nusl.cz/ntk/nusl-233952.
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Disertační práce formuluje asymptotické odhady řešení tzv. sublineárních a superlineárních diferenciálních rovnic se zpožděním. V těchto odhadech vystupuje řešení pomocných funkcionálních rovnic a nerovností. Dále práce pojednává o kvalitativních vlastnostech diferenčních rovnic se zpožděním, které vznikly diskretizací studovaných diferenciálních rovnic. Pozornost je věnována souvislostem asympotického chování řešení rovnic ve spojitém a diskrétním tvaru, a to v obecném i v konkrétních případech. Studována je rovněž stabilita numerické diskretizace vycházející z $\theta$-metody. Práce obsahuje několik příkladů ilustrujících dosažené výsledky.
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Newbury, Golnar. "A Numerical Study of a Delay Differential Equation Model for Breast Cancer." Thesis, Virginia Tech, 2007. http://hdl.handle.net/10919/34420.
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In this thesis we construct a new model of the immune response to the growth of breast cancer cells and investigate the impact of certain drug therapies on the cancer. We use delay differential equations to model the interaction of breast cancer cells with the immune system. The new model is constructed by combining two previous models. The first model accounts for different cell cycles and includes terms to evaluate drug treatments, but ignores quiescent tumor cells. The second model includes quiescent cells, but ignores the immune response and drug treatments. The new model is obtained by combining and modifying these two models to account for quiescent cells, immune cells and includes drug intervention terms. This new model is used to evaluate the effects of pulsed applications of the drug Paclitaxel for models with and without quiescent cells. We use sensitivity equation methods to analyze the sensitivity of the model with respect to the initial number of immune cytotoxic T-cells. Numerical experiments are conducted to compare the model predictions to observed behavior.Master of Science
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Dražková, Jana. "Stability of Neutral Delay Differential Equations and Their Discretizations." Doctoral thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2014. http://www.nusl.cz/ntk/nusl-234204.
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Disertační práce se zabývá asymptotickou stabilitou zpožděných diferenciálních rovnic a jejich diskretizací. V práci jsou uvažovány lineární zpožděné diferenciální rovnice s~konstantním i neohraničeným zpožděním. Jsou odvozeny nutné a postačující podmínky popisující oblast asymptotické stability jak pro exaktní, tak i diskretizovanou lineární neutrální diferenciální rovnici s konstantním zpožděním. Pomocí těchto podmínek jsou porovnány oblasti asymptotické stability odpovídajících exaktních a diskretizovaných rovnic a vyvozeny některé vlastnosti diskrétních oblastí stability vzhledem k měnícímu se kroku použité diskretizace. Dále se zabýváme lineární zpožděnou diferenciální rovnicí s neohraničeným zpožděním. Je uveden popis jejích exaktních a diskrétních oblastí asymptotické stability spolu s asymptotickým odhadem jejich řešení. V závěru uvažujeme lineární diferenciální rovnici s více neohraničenými zpožděními.
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Khavanin, Mohammad. "The Method of Mixed Monotony and First Order Delay Differential Equations." Pontificia Universidad Católica del Perú, 2014. http://repositorio.pucp.edu.pe/index/handle/123456789/96643.
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In this paper I extend the method of mixed monotony, to construct monotone sequences that converge to the unique solution of an initial value delay differential equation.En este artículo se prueba una generalización del método de monotonía mixta, para construir sucesiones monótonas que convergen a la solución única de una ecuación diferencial de retraso con valor inicial.
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Magpantay, Felicia Maria. "On the stability and numerical stability of a model state dependent delay differential equation." Thesis, McGill University, 2012. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=106523.
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In this thesis the following model state dependent delay differential equation is considered,epsilon.u'(t) = mu.u(t) + sigma.u(t-a-c.u(t)).For fixed epsilon, a and c, the analytical stability region of this equation is known and it is the same for both the constant delay (c=0) and state dependent delay (c nonzero) cases. Different approaches are used to directly prove stability in parts of this analytic region for the state dependent DDE: first using a Gronwall argument and then using a Lyapunov-Razumikhin method which is a generalisation of the work of Barnea [6] who considered the mu=c=0 case. The parameter regions in which stability is proven by these methods contain the entire delay independent portion of the analytical stability region and parts of the delay dependent portion. These methods are then extended to show the stability of the backward Euler method with linear interpolation applied to the model DDE. Using the Lyapunov-Razumikhin method, stability is proven in larger parameter regions that depend on the stepsize, but always contain the region found for the DDE. Analytic expressions for regions in which general Theta methods are stable were also derived and evaluated numerically. In the last chapter a new scheme for numerically integrating scalar DDEs with multiple state dependent delays is presented. This scheme is based on singularly diagonally implicit Runge-Kutta (SDIRK) methods in order to solve stiff problems such as the equation above with small epsilon. Due to the nature of SDIRK methods, if there is no overlapping then at each step a set of scalar equations are solved one-by-one using a Newton-bisection algorithm. New continuous extensions which are piecewise polynomial are chosen to accompany the SDIRK scheme so as not to destroy the SDIRK structure in the overlapping cases and to avoid the problem of spiking when there is a sharp change in the numerical solution.Dans cette thèse, l'équation différentielle à retard (DDE) modèle d'état dépendant suivante est considérée,epsilon.u'(t) = mu.u(t) + sigma.u(t-a-c.u(t)).Pour epsilon, a et c fixés, la région de stabilité analytique de cette équation est connue et est la même pour le retard constant (c=0) ainsi que pour l'état de retard dépendant (c non nulle). Différentes approches sont utilisées pour prouver directement la stabilité dans certaines parties de cette région analytique pour la DDE d'état dépendant: d'abord en utilisant un argument de Gronwall, puis en utilisant une méthode de Lyapunov-Razumikhin qui est une généralisation du travail de Barnea [6] qui considère le cas mu = c = 0. Les régions de paramètres dans lesquelles la stabilité est prouvée par ces méthodes contiennent la partie entière de retard indépendant de la région de stabilité analytique et certaines parties de la portion de retard dépendant. Ces méthodes sont ensuite étendues pour montrer la stabilité de la méthode d'Euler arrière avec interpolation linéaire appliquée à la DDE modèle. En utilisant la méthode de Lyapunov-Razumikhin, la stabilité est prouvée dans des regions de paramètres plus grandes qui dépendent du pas de discrétisation, mais qui contiennent toujours la région trouvée pour la DDE. Des expressions analytiques pour les régions dans lesquelles les méthodes Theta générales sont stables ont également été tirées et évaluées numériquement. Dans le dernier chapitre d'un nouveau schéma pour intégration numérique des DDE scalaires avec des multiples retards d'état dépendant est présenté. Ce schéma est basé sur des méthodes de Runge-Kutta singulièrement et diagonalement implicites (SDIRK) afin de résoudre des problèmes raides tels que l'équation ci-dessus avec des petites valeurs de epsilon. En raison de la nature des méthodes SDIRK, s'il n'y a pas de chevauchement, alors à chaque iteration un ensemble d'équations scalaires sont résolues, une par une, en utilisant un algorithme de bissection de Newon. Des nouvelles extensions continues qui sont polynomiales par morceaux sont choisies pour accompagner le schéma SDIRK afin de ne pas détruire la structure SDIRK dans les cas de chevauchement et pour éviter le problème des piques quand il y a un changement brusque de la solution numérique.
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Jánský, Jiří. "Delay Difference Equations and Their Applications." Doctoral thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2010. http://www.nusl.cz/ntk/nusl-233892.
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Disertační práce se zabývá vyšetřováním kvalitativních vlastností diferenčních rovnic se zpožděním, které vznikly diskretizací příslušných diferenciálních rovnic se zpožděním pomocí tzv. $\Theta$-metody. Cílem je analyzovat asymptotické vlastnosti numerického řešení těchto rovnic a formulovat jeho horní odhady. Studována je rovněž stabilita vybraných numerických diskretizací. Práce obsahuje také srovnání s dosud známými výsledky a několik příkladů ilustrujících hlavní dosažené výsledky.
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Zhang, Zhengyang. "A class of state-dependent delay differential equations and applications to forest growth." Thesis, Bordeaux, 2018. http://www.theses.fr/2018BORD0062/document.
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Cette thèse est consacrée à l'étude d'une classe d'équations différentielles à retard dépendant de l'état -- ces équations provenant d'un modèle structuré en taille. La principale motivation de cette thèse provient de la volonté d'ajuster les paramètres du système d'équations étudiées vis-à-vis des données générées par un simulateur de forêts, appelé SORTIE. Deux types de forêts sont étudiés ici: d'une part une forêt ne comportant qu'une seule espèce d'arbre, et d'autre part une forêt comportant deux espèces d'arbres (au chapitre 2). Les simulations numériques du système d'équations correspondent relativement bien aux données générées par SORTIE, ce qui montre que le système considéré peut être utilisé afin d'écrire la dynamique de populations d'une forêt. De plus, un modèle plus étendu prenant en compte la position spatiale des arbres est proposé dans le chapitre 2, dans le cas de forêts possédant deux espèces d'arbres. Les simulations numériques de ce modèle permettent de visualiser la propagation spatiale des forêts. Les chapitres 3 et 4 se concentrent sur l'analyse mathématique des équations différentielles à retard considérées. Les propriétés du semi-flot associé au système sont étudiées au chapitre 3, où l'on démontre en particulier que ce semi-flot n'est pas continu en temps. Le caractère dissipatif et borné du semi-flot, pour des modèles de forêts comportant une ou deux espèces d'arbres, est étudié dans le chapitre 4. En outre, afin d'étudier la dynamique de population d'une forêt (d'une seule espèce d'arbre) après l'introduction d'un parasite, nous construisons dans le chapitre 5 un système proie-prédateur dont la proie (à savoir la forêt) est modélisée par le système d'équations différentielles à retard dépendant de l'état étudié auparavant, et dont le prédateur (à savoir le parasite) est modélisé par une équation différentielle ordinaire. De nombreuses simulations numériques associées à différents scénarios sont faites, afin d'explorer le comportement complexe des solutions du au couplage proie-prédateur et les équations à retard dépendant de l'étatThis thesis is devoted to the studies of a class of state-dependent delay differential equations. This class of equations is derived from a size-structured model.The motivation comes from the parameter fittings of this system to a forest simulator called SORTIE. Cases of both single species forest and two-species forest are considered in Chapter 2. The numerical simulations of the system correspond relatively very well to the forest data generated by SORTIE, which shows that this system is able to be used to describe the population dynamics of forests. Moreover, an extended model considering the spatial positions of trees is also proposed in Chapter 2 for the two-species forest case. From the numerical simulations of this spatial model one can see the diffusion of forests in space. Chapter 3 and 4 focus on the mathematical analysis of the state-dependent delay differential equations. The properties of semiflow generated by this system are studied in Chapter 3, where we find that this semiflow is not time-continuous. The boundedness and dissipativity of the semiflow for both single species model and multi-species model are studied in Chapter 4. Furthermore, in order to study the population dynamics after the introduction of parasites into a forest, a predator-prey system consisting of the above state-dependent delay differential equation (describing the forest) and an ordinary differential equation (describing the parasites) is constructed in Chapter 5 (only the single species forest is considered here). Numerical simulations in several scenarios and cases are operated to display the complex behaviours of solutions appearing in this system with the predator-prey relation and the state-dependent delay
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Kumar, Chaman. "Explicit numerical schemes of SDEs driven by Lévy noise with super-linear coeffcients and their application to delay equations." Thesis, University of Edinburgh, 2015. http://hdl.handle.net/1842/15946.
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We investigate an explicit tamed Euler scheme of stochastic differential equation with random coefficients driven by Lévy noise, which has super-linear drift coefficient. The strong convergence property of the tamed Euler scheme is proved when drift coefficient satisfies one-sided local Lipschitz condition whereas diffusion and jump coefficients satisfy local Lipschitz conditions. A rate of convergence for the tamed Euler scheme is recovered when local Lipschitz conditions are replaced by global Lipschitz conditions and drift satisfies polynomial Lipschitz condition. These findings are consistent with those of the classical Euler scheme. New methodologies are developed to overcome challenges arising due to the jumps and the randomness of the coefficients. Moreover, as an application of these findings, a tamed Euler scheme is proposed for the stochastic delay differential equation driven by Lévy noise with drift coefficient that grows super-linearly in both delay and non-delay variables. The strong convergence property of the tamed Euler scheme for such SDDE driven by Lévy noise is studied and rate of convergence is shown to be consistent with that of the classical Euler scheme. Finally, an explicit tamed Milstein scheme with rate of convergence arbitrarily close to one is developed to approximate the stochastic differential equation driven by Lévy noise (without random coefficients) that has super-linearly growing drift coefficient.
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Béreš, Lukáš. "Matematické modelování pomocí diferenciálních rovnic." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2017. http://www.nusl.cz/ntk/nusl-318707.
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Diplomová práce je zaměřena na problematiku nelineárních diferenciálních rovnic. Obsahuje věty důležité k určení chování nelineárního systému pouze za pomoci zlinearizovaného systému, což je následně ukázáno na rovnici matematického kyvadla. Dále se práce zabývá problematikou diferenciálních rovnic se zpoždéním. Pomocí těchto rovnic je možné přesněji popsat některé reálné systémy, především systémy, ve kterých se vyskytují časové prodlevy. Zpoždění ale komplikuje řešitelnost těchto rovnic, což je ukázáno na zjednodušené rovnici portálového jeřábu. Následně je zkoumána oscilace lineární rovnice s nekonstantním zpožděním a nalezení podmínek pro koeficienty rovnice zaručující oscilačnost každého řešení.
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Obrátil, Štěpán. "Vyšetřování stability numerických metod pro diferenciální rovnice se zpožděným argumentem." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2019. http://www.nusl.cz/ntk/nusl-400513.
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The thesis deals with numerical analysis of delay differential equations. Particularly, the -method is applied to the pantograph equation considering equidistant and quasi-geometric mesh. Qualitative properties of the numerical methods are demonstrated on several special cases of the pantograph equation.
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Berntson, B. K. "Integrable delay-differential equations." Thesis, University College London (University of London), 2017. http://discovery.ucl.ac.uk/1566618/.
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Delay-differential equations are differential-difference equations in which the derivatives and shifts are taken with respect to the same variable. This thesis is concerned with these equations from the perspective of the theory of integrable systems, and more specifically, Painlevé equations. Both the classical Painlevé equations and their discrete analogues can be obtained as deautonomizations of equations solved by two-parameter families of elliptic functions. In analogy with this paradigm, we consider autonomous delay-differential equations solved by elliptic functions, delay-differential extensions of the Painlevé equations, and the interrelations between these classes of equations. We develop a method to identify delay-differential equations that admit families of elliptic solutions with at least two degrees of parametric freedom and apply it to two natural 16-parameter families of delay-differential equations. Some of the resulting equations are related to known models including the differential-difference sine-Gordon equation and the Volterra lattice; the corresponding new solutions to these and other equations are constructed in a number of examples. Other equations we have identified appear to be new. Bäcklund transformations for the classical Painlevé equations provide a source of delay-differential Painlevé equations. These transformations were previously used to derive discrete Painlevé equations. We use similar methods to identify delay-differential equations with continuum limits to the first classical Painlevé equation. The equations we identify are solved by elliptic functions in particular limits corresponding to the autonomous limit of the classical first Painlevé equation.
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Bou, Saba David. "Analyse et commande modulaires de réseaux de lois de bilan en dimension infinie." Thesis, Lyon, 2018. http://www.theses.fr/2018LYSEI084/document.
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Les réseaux de lois de bilan sont définis par l'interconnexion, via des conditions aux bords, de modules élémentaires individuellement caractérisés par la conservation de certaines quantités. Des applications industrielles se trouvent dans les réseaux de lignes de transmission électriques (réseaux HVDC), hydrauliques et pneumatiques (réseaux de distribution du gaz, de l'eau et du fuel). La thèse se concentre sur l'analyse modulaire et la commande au bord d'une ligne élémentaire représentée par un système de lois de bilan en dimension infinie, où la dynamique de la ligne est prise en considération au moyen d'équations aux dérivées partielles hyperboliques linéaires du premier ordre et couplées deux à deux. Cette dynamique permet de modéliser d'une manière rigoureuse les phénomènes de transport et les vitesses finies de propagation, aspects normalement négligés dans le régime transitoire. Les développements de ces travaux sont des outils d'analyse qui testent la stabilité du système, et de commande au bord pour la stabilisation autour d'un point d'équilibre. Dans la partie analyse, nous considérons un système de lois de bilan avec des couplages statiques aux bords et anti-diagonaux à l’intérieur du domaine. Nous proposons des conditions suffisantes de stabilité, tant explicites en termes des coefficients du système, que numériques par la construction d'un algorithme. La méthode se base sur la reformulation du problème en une analyse, dans le domaine fréquentiel, d'un système à retard obtenu en appliquant une transformation backstepping au système de départ. Dans le travail de stabilisation, un couplage avec des dynamiques décrites par des équations différentielles ordinaires (EDO) aux deux bords des EDP est considéré. Nous développons une transformation backstepping (bornée et inversible) et une loi de commande qui, à la fois stabilise les EDP à l'intérieur du domaine et la dynamique des EDO, et élimine les couplages qui peuvent potentiellement mener à l’instabilité. L'efficacité de la loi de commande est illustrée par une simulation numériqueNetworks of balance laws are defined by the interconnection, via boundary conditions, of elementary modules individually characterized by the conservation of physical quantities. Industrial applications of such networks can be found in electric (HVDC networks), hydraulic and pneumatic (gas, water and oil distribution) transmission lines. The thesis is focused on modular analysis and boundary control of an elementary line represented by a system of balance laws in infinite dimension, where the dynamics of the line is taken into consideration by means of first order two by two coupled linear hyperbolic partial differential equations. This representation allows to rigorously model the transport phenomena and finite propagation speed, aspects usually neglected in transient regime. The developments of this work are analysis tools that test the stability, as well as boundary control for the stabilization around an equilibrium point. In the analysis section, we consider a system of balance laws with static boundary conditions and anti-diagonal in-domain couplings. We propose sufficient stability conditions, explicit in terms of the system coefficients, and numerical by constructing an algorithm. The method is based on reformulating the analysis problem as an analysis of a delay system in the frequency domain, obtained by applying a backstepping transform to the original system. In the stabilization work, couplings with dynamic boundary conditions, described by ordinary differential equations (ODE), at both boundaries of the PDEs are considered. We develop a backstepping (bounded and invertible) transform and a control law that at the same time, stabilizes the PDEs inside the domain and the ODE dynamics, and eliminates the couplings that are a potential source of instability. The effectiveness of the control law is illustrated by a numerical simulation
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Allen, Brenda. "Non-smooth differential delay equations." Thesis, University of Oxford, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.390472.
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Norton, Trevor Michael. "Galerkin Approximations of General Delay Differential Equations with Multiple Discrete or Distributed Delays." Thesis, Virginia Tech, 2018. http://hdl.handle.net/10919/83825.
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Delay differential equations (DDEs) are often used to model systems with time-delayed effects, and they have found applications in fields such as climate dynamics, biosciences, engineering, and control theory. In contrast to ordinary differential equations (ODEs), the phase space associated even with a scalar DDE is infinite-dimensional. Oftentimes, it is desirable to have low-dimensional ODE systems that capture qualitative features as well as approximate certain quantitative aspects of the DDE dynamics. In this thesis, we present a Galerkin scheme for a broad class of DDEs and derive convergence results for this scheme. In contrast to other Galerkin schemes devised in the DDE literature, the main new ingredient here is the use of the so called Koornwinder polynomials, which are orthogonal polynomials under an inner product with a point mass. A main advantage of using such polynomials is that they live in the domain of the underlying linear operator, which arguably simplifies the related numerical treatments. The obtained results generalize a previous work to the case of DDEs with multiply delays in the linear terms, either discrete or distributed, or both. We also consider the more challenging case of discrete delays in the nonlinearity and obtain a convergence result by assuming additional assumptions about the Galerkin approximations of the linearized systems.Master of Science
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Piddubna, Ganna Konstantinivna. "Lineární maticové diferenciální rovnice se zpožděním." Doctoral thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2014. http://www.nusl.cz/ntk/nusl-233626.
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V předložené práci se zabýváme hledáním řešení lineární diferenciální maticové rovnice se zpožděním x'(t)=A0x(t)+A1x(t-tau), kde A0, A1 jsou konstantní matice, tau>0 je konstantní zpoždění. Dále se zabýváme odvozením podmínek stability řešení systému a řiditelnosti daného systému. Pro řešení tohoto systému byla použita metoda "krok za krokem". Řešení bylo nalezeno jak v rekurentní formě tak i v obecném tvaru. Je provedena analýza stability a asymptotické stability řešení systému. Jsou zformulovány podmínky stability. Hlavní roli v analýze stability měla metoda Lyapunovových funkcionálů. Jsou zformulovány nutné a postačující podmínky řiditelnosti pro případ systémů se stejnými maticemi a je zkonstruována řídící funkce. Jsou odvozeny postačující podmínky pro řiditelnost v případě komutujících matic a v případě obecných matic a je sestrojena řídící funkce. Všechny výsledky jsou ilustrovány na netriviálních příkladech.
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Taylor, S. Richard. "Probabilistic Properties of Delay Differential Equations." Thesis, University of Waterloo, 2004. http://hdl.handle.net/10012/1183.
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Systems whose time evolutions are entirely deterministic can nevertheless be studied probabilistically, i. e. in terms of the evolution of probability distributions rather than individual trajectories. This approach is central to the dynamics of ensembles (statistical mechanics) and systems with uncertainty in the initial conditions. It is also the basis of ergodic theory--the study of probabilistic invariants of dynamical systems--which provides one framework for understanding chaotic systems whose time evolutions are erratic and for practical purposes unpredictable. Delay differential equations (DDEs) are a particular class of deterministic systems, distinguished by an explicit dependence of the dynamics on past states. DDEs arise in diverse applications including mathematics, biology and economics. A probabilistic approach to DDEs is lacking. The main problems we consider in developing such an approach are (1) to characterize the evolution of probability distributions for DDEs, i. e. develop an analog of the Perron-Frobenius operator; (2) to characterize invariant probability distributions for DDEs; and (3) to develop a framework for the application of ergodic theory to delay equations, with a view to a probabilistic understanding of DDEs whose time evolutions are chaotic. We develop a variety of approaches to each of these problems, employing both analytical and numerical methods. In transient chaos, a system evolves erratically during a transient period that is followed by asymptotically regular behavior. Transient chaos in delay equations has not been reported or investigated before. We find numerical evidence of transient chaos (fractal basins of attraction and long chaotic transients) in some DDEs, including the Mackey-Glass equation. Transient chaos in DDEs can be analyzed numerically using a modification of the "stagger-and-step" algorithm applied to a discretized version of the DDE.
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Ron, Eyal [Verfasser]. "Hysteresis-Delay Differential Equations / Eyal Ron." Berlin : Freie Universität Berlin, 2016. http://d-nb.info/1121588026/34.
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Hines, Gwendolen. "Dependence of the attractor on the delay for delay-differential equations." Diss., Georgia Institute of Technology, 1993. http://hdl.handle.net/1853/28954.
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Zhang, Wenkui. "Numerical analysis of delay differential and integro-differential equations." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0011/NQ42489.pdf.
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Bahar, Arifah. "Applications of stochastic differential equations and stochastic delay differential equations in population dynamics." Thesis, University of Strathclyde, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.415294.
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Rossi, Marcelo. "Modelo matemático da resposta imune à infecção pelo vírus HIV-1." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/87/87131/tde-12012009-150807/.
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Avanços recentes nos conhecimentos sobre a infecção viral e AIDS tem levado pacientes soropositivos a uma melhor qualidade de vida. A determinação de quais populações celulares ou qual mecanismo imunológico seja mais relevante para instalação da epidemia conduz a novos patamares de possibilidades de novas drogas antiretrovirais e tratamento mais eficientes. O uso de modelagem matemática, para a epidemiologia, correlaciona indivíduos (neste caso células) e doença (o vírus) através de equações diferenciais, onde se quer observar as condições necessárias para a instalação ou não da doença. Neste trabalho, observou-se através das simulações, que o componente mais importante, depois do linfócito TCD4+, é a célula macrófago (por ser um reservatório de proliferação viral), que a infecção ocorre várias vezes ao longo do tempo (devido o processo de apresentação de antígenos) e que os linfócitos CTL são ineficientes em erradicar a infecção pelo vírus HIV-1, que pode ser um simples fenômeno de co-adaptação.Recent advances in knowledge about the viral infection and AIDS seropositive patients has led to a better life quality. The determination of what people or cellular immune mechanism which is more relevant for the epidemic installation leads to new levels of possibilities to new antiretroviral drugs discovers and more efficient treatment. Mathematical modeling use on epidemiology, correlates individuals (this case cells) and illness (the virus) through differential equations, where want to observe the conditions necessary to the installation or not the disease. In this study, it was observed through simulations, that the most important component, after lymphocyte CD4 T cells, macrophages is the cell (as a reservoir of viral proliferation) that the infection occurs repeatedly over time (because of the antigen presenting process) and CTL lymphocytes are inefficient in eradicating the infection by HIV-1, which may be a simple phenomenon of co-adaptation.
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Dokyi, Martha. "Diferenciální rovnice se zpožděním v dynamických systémech." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2021. http://www.nusl.cz/ntk/nusl-445464.
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Tato práce je přehledem zpožděných diferenciálních rovnic v dynamických systémech. Počínaje obecným přehledem zpožděných diferenciálních rovnic představujeme koncept zpožděných diferenciálů a použití jeho modelů, od biologie a populační dynamiky po fyziku a inženýrství. Poskytneme také přehled Dynamické systémy a diferenciální rovnice zpoždění v dynamických systémech. Oblastí pro modelování s rovnicemi zpožďovacích diferenciálů je Epidemiologie. Důraz je kladen na vývoj epidemiologického modelu Susceptible-Infected-Removed (SIR) bez časového zpoždění. Analyzujeme naše dva modely v rovnováze a lokální stabilitě pomocí předpokládaných dat COVID -19. Výsledky by byly porovnány mezi modelem bez zpoždění a modelem se zpožděním.
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Vittadello, Sean T. "Mathematical models for cell migration and proliferation informed by visualisation of the cell cycle." Thesis, Queensland University of Technology, 2020. https://eprints.qut.edu.au/204074/1/Sean_Vittadello_Thesis.pdf.
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Cell migration and proliferation are essential for normal physiological processes, however their misregulation contributes to pathologies including cancer. In this thesis we develop and analyse new mathematical models of cell migration and proliferation, based on new experimental studies that provide visualisation of cell cycle progression, to improve understanding of the migration and proliferation of cells. In particular, we investigate cell migration as a function of cell cycle dynamics, normally-hidden cell synchronisation in cellular assays, whether cell migration and proliferation are mutually exclusive processes, and cellular mechanisms that contribute to heterogeneous cell proliferation.
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Reiss, Markus. "Nonparametric estimation for stochastic delay differential equations." [S.l.] : [s.n.], 2002. http://deposit.ddb.de/cgi-bin/dokserv?idn=964782480.
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Ballinger, George Henri. "Qualitative theory of impulsive delay differential equations." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/NQ51178.pdf.
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Wille, David Richard. "The numerical solution of delay-differential equations." Thesis, University of Manchester, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.291519.
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Lumb, Patricia M. "Delay differential equations : detection of small solutions." Thesis, University of Chester, 2004. http://hdl.handle.net/10034/68595.
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This thesis concerns the development of a method for the detection of small solutions to delay differential equations. The detection of small solutions is important because their presence has significant influence on the analytical prop¬erties of an equation. However, to date, analytical methods are of only limited practical use. Therefore this thesis focuses on the development of a reliable new method, based on finite order approximations of the underlying infinite dimen¬sional problem, which can detect small solutions. Decisions (concerning the existence, or otherwise, of small solutions) based on our visualisation technique require an understanding of the underlying methodol¬ogy behind our approach. Removing this need would be attractive. The method we have developed can be automated, and at the end of the thesis we present a prototype Matlab code for the automatic detection of small solutions to delay differential equations.
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Ezeofor, Victory S. "Analysis of differential-delay equations for biology." Thesis, University of Nottingham, 2017. http://eprints.nottingham.ac.uk/39940/.
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In this thesis, we investigate the role of time delay in several differential-delay equation focusing on the negative autogenous regulation. We study these models for little or no delay to when the model has a very large delay parameter. We start with the logistic differential-delay equation applying techniques that would be used in subsequent chapters for other models being studied. A key goal of this research is to identify where the structure of the system does change. First, we investigate these models for critical point and study their behaviour close to these points. Of keen interest is the Hopf bifurcation points where we analyse the parameter associated with the Hopf point. The weakly nonlinear analysis carried out using the method of multiple time scale is used to give more insight to these model. The centre manifold method is shown to support the result derived using the multiple time scale. Then the second study carried out is the study of the transition from a sinelike wave to a square wave. This is analysed and a scale deduced at which this transition gradually takes place. One of the key areas we focused on in the large delay is to solve for a certain constant a' associated with the period of oscillation. The effect of the delayed parameter is shown throughout this thesis as a major contributor to the properties of both the logistic delay and the negative autogenous regulation.
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Reiß, Markus. "Nonparametric estimation for stochastic delay differential equations." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät II, 2002. http://dx.doi.org/10.18452/14741.
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Sei (X(t), t>= -r) ein stationärer stochastischer Prozess, der die affine stochastische Differentialgleichung mit Gedächtnis dX(t)=L(X(t+s))dt+sigma dW(t), t>= 0, löst, wobei sigma>0, (W(t), t>=0) eine Standard-Brownsche Bewegung und L ein stetiges lineares Funktional auf dem Raum der stetigen Funktionen auf [-r,0], dargestellt durch ein endliches signiertes Maß a, bezeichnet. Wir nehmen an, dass eine Trajektorie (X(t), -r 0, konvergiert. Diese Rate ist schlechter als in vielen klassischen Fällen. Wir beweisen jedoch eine untere Schranke, die zeigt, dass keine Schätzung eine bessere Rate im Minimax-Sinn aufweisen kann. Für zeit-diskrete Beobachtungen von maximalem Abstand Delta konvergiert die Galerkin-Schätzung immer noch mit obiger Rate, sofern Delta is in etwa von der Ordnung T^(-1/2). Hingegen wird bewiesen, dass für festes Delta unabhängig von T die Rate sich signifikant verschlechtern muss, indem eine untere Schranke von T^(-s/(2s+6)) gezeigt wird. Außerdem wird eine adaptive Schätzung basierend auf Wavelet-Thresholding-Techniken für das assoziierte schlechtgestellte Problem konstruiert. Diese nichtlineare Schätzung erreicht die obige Minimax-Rate sogar für die allgemeinere Klasse der Besovräume B^s_(p,infinity) mit p>max(6/(2s+3),1). Die Restriktion p>=max(6/(2s+3),1) muss für jede Schätzung gelten und ist damit inhärent mit dem Schätzproblem verknüpft. Schließlich wird ein Hypothesentest mit nichtparametrischer Alternative vorgestellt, der zum Beispiel für das Testen auf Gedächtnis verwendet werden kann. Dieser Test ist anwendbar für eine L^2-Trennungsrate zwischen Hypothese und Alternative der Ordnung T^(-s/(2s+2.5)). Diese Rate ist wiederum beweisbar optimal für jede mögliche Teststatistik. Für die Beweise müssen die Parameterabhängigkeit der stationären Lösungen sowie die Abbildungseigenschaften der assoziierten Kovarianzoperatoren detailliert bestimmt werden. Weitere Resultate von allgemeinem Interessen beziehen sich auf die Mischungseigenschaft der stationären Lösung, eine Fallstudie zu exponentiellen Gewichtsfunktionen sowie der Approximation des stationären Prozesses durch autoregressive Prozesse in diskreter Zeit.Let (X(t), t>= -r) be a stationary stochastic process solving the affine stochastic delay differential equation dX(t)=L(X(t+s))dt+sigma dW(t), t>= 0, with sigma>0, (W(t), t>=0) a standard one-dimensional Brownian motion and with a continuous linear functional L on the space of continuous functions on [-r,0], represented by a finite signed measure a. Assume that a trajectory (X(t), -r 0. This rate is worse than those obtained in many classical cases. However, we prove a lower bound, stating that no estimator can attain a better rate of convergence in a minimax sense. For discrete time observations of maximal distance Delta, the Galerkin estimator still attains the above asymptotic rate if Delta is roughly of order T^(-1/2). In contrast, we prove that for observation intervals Delta, with Delta independent of T, the rate must deteriorate significantly by providing the rate estimate T^(-s/(2s+6)) from below. Furthermore, we construct an adaptive estimator by applying wavelet thresholding techniques to the corresponding ill-posed inverse problem. This nonlinear estimator attains the above minimax rate even for more general classes of Besov spaces B^s_(p,infinity) with p>max(6/(2s+3),1). The restriction p >= 6/(2s+3) is shown to hold for any estimator, hence to be inherently associated with the estimation problem. Finally, a hypothesis test with a nonparametric alternative is constructed that could for instance serve to decide whether a trajectory has been generated by a stationary process with or without time delay. The test works for an L^2-separation rate between hypothesis and alternative of order T^(-s/(2s+2.5)). This rate is again shown to be optimal among all conceivable tests. For the proofs, the parameter dependence of the stationary solutions has to be studied in detail and the mapping properties of the associated covariance operators have to be determined exactly. Other results of general interest concern the mixing properties of the stationary solution, a case study for exponential weight functions and the approximation of the stationary process by discrete time autoregressive processes.
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Nishiguchi, Junya. "Retarded functional differential equations with general delay structure." 京都大学 (Kyoto University), 2017. http://hdl.handle.net/2433/225381.
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Zhang, Yandong Sinha S. C. "Some techniques in the control of dynamic systems with periodically varying coefficients." Auburn, Ala., 2007. http://hdl.handle.net/10415/1346.
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Ogrowsky, Arne [Verfasser]. "Random Differential Equations with Random Delay / Arne Ogrowsky." München : Verlag Dr. Hut, 2011. http://d-nb.info/1017353352/34.
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Karoui, Abderrazek. "On the numerical solution of delay differential equations." Thesis, University of Ottawa (Canada), 1992. http://hdl.handle.net/10393/7673.
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A numerical method for the treatment of non-vanishing lag state dependent delay differential equations is developed in this work. This method is based on a (5,6) Runge-Kutta formula pair. The delayed term is approximated by a three-point Hermite polynomial. In order to obtain a highly accurate numerical scheme, special attention is given to the characterization and the localization of the derivative jump discontinuities of the solution. Some real-life problems are used to test the new method and compare it with existing ones.
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Guillouzic, Steve. "Fokker-Planck approach to stochastic delay differential equations." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/NQ58279.pdf.
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Losson, Jérôme. "Multistability and probabilistic properties of differential delay equations." Thesis, McGill University, 1991. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=60514.
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The dynamics of a class of nonlinear delay differential equations (D.D.E's) is studied. We focus attention on D.D.E's with a discrete delay used as models for production/destruction processes. The design of an electronic analog computer simulating an integrable D.D.E is presented. This computer is used to illustrate the presence of bistable solutions in the system. The multistability is investigated numerically with an analytic integration algorithm. Higher order multistability is reported, and the structure of basin boundaries in the space of initial functions is investigated. Pathological dependence of solution behavior on the initial function is shown to be present in large regions of parameter space. A D.D.E obtained as the singular perturbation of the one dimensional "hat map" is studied numerically. Several schemes to undertake a statistical analysis of the equation are presented. We first focus attention on the construction of densities along trajectories, and then on the construction of densities for ensembles of trajectories generated by ensembles of initial functions. A cycling of densities is observed in both cases, and compared to the asymptotic periodicity of the Frobenius-Perron operator for the hat map. Functional analytic techniques used for the analysis of stochastic wave propagation in continuous media and in quantum field theory are extended to the statistical study of D.D.E's, and provide a theoretical framework within which to study D.D.E dynamics in the spirit of ergodic theory and statistical mechanics.
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Tannerah, Lamees Hassan. "Modelling a dairy herd using delay differential equations." Thesis, University of Liverpool, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.427024.
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Ribeiro, Maria de Fátima Fabião. "Equação diferencial com atraso das funções geradoras até à função W-Lambert : Contributo para uma Aplicação à Economia, Introdução do Efeito de Atraso no Modelo de Solow." Doctoral thesis, Instituto Superior de Economia e Gestão, 2005. http://hdl.handle.net/10400.5/4719.
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Doutoramento em Matemática Aplicada à Economia e GestãoO objectivo desta dissertação é obter a solução da equação diferencial com atraso de primeira ordem com coeficientes constantes expressa em termos da função W-Lambert. Ao definir o Problema Inicial Básico (PIB) como um caso particular daquela equação e aplicado o Método do Passo, captou-se um tipo de estrutura em árvore nas soluções definidas em cada passo do método. Esta constatação levou ao desenvolvimento de um processo construtivo da solução do PIB. Com este procedimento obtiveram-se dois resultados principais. O primeiro consiste na validade da conjectura feita inicialmente sobre a solução do PIB, a de que existe uma função geradora de uma classe específica de polinómios no atraso. O segundo revela a estrutura combinatória associada às equações diferenciais com atraso, mostrando como a relação existente entre a função W-Lambert e a função árvore justifica o efeito em árvore que então se intuiu. Pretendeu-se ainda, através de uma aplicação à Economia, avaliar as alterações que o modelo de Solow reflecte quando nele é introduzido o efeito do atraso na modelação do progresso tecnológico e da força laboral, modificando as hipóteses que habitualmente são formuladas sobre aquelas variáveis económicas.
The scope of this dissertation is to obtain the solution of the first order delay differential equation with constant coefficients expressed in terms of the W-Lambert function. Defining the Basic Initial Problem (BIP) as being a particular case of those equations, and applying the step method, a type of tree structure was captured in the solutions defined in each step of the method. This observation led to the development of a constructive process of the BIP solution. With this procedure two main conclusions were achieved. The first consists on the validation of the conjecture initially made about the BIP solution that generating function of a specific class of polynomials in the delay exists. The second reveals a combinatorial structure associated with the delay differential equations, therefore showing how the existent relation between W-Lambert function and tree function justifies the tree effect as foreseen. Furthermore it was attempted, through an application to Economics, to evaluate the changes that the Solow model reflects when introducing the effect of the delay on modeling the technical progress and the labour force, modifying the assumptions that are usually formulated about those economic variables.
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Swain, Robin. "The Morris-Lecar equations with delay /." Internet access available to MUN users only, 2003. http://collections.mun.ca/u?/theses,162993.
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René, Alexandre. "Spectral Solution Method for Distributed Delay Stochastic Differential Equations." Thesis, Université d'Ottawa / University of Ottawa, 2016. http://hdl.handle.net/10393/34327.
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Stochastic delay differential equations naturally arise in models of complex natural phenomena, yet continue to resist efforts to find analytical solutions to them: general solutions are limited to linear systems with additive noise and a single delayed term. In this work we solve the case of distributed delays in linear systems with additive noise. Key to our solution is the development of a consistent interpretation for integrals over stochastic variables, obtained by means of a virtual discretization procedure. This procedure makes no assumption on the form of noise, and would likely be useful for a wider variety of cases than those we have considered. We show how it can be used to map the distributed delay equation to a known multivariate system, and obtain expressions for the system's time-dependent mean and autocovariance. These are in the form of series over the system's natural modes and completely define the solution. — An interpretation of the system as an amplitude process is explored. We show that for a wide range of realistic parameters, dynamics are dominated by only a few modes, implying that most of the observed behaviour of stochastic delayed equations is constrained to a low-dimensional subspace. — The expression for the autocovariance is given particular attention. A recurring problem for stochastic delay equations is the description of their temporal structure. We show that the series expression for the autocovariance does converge over a meaningful range of time lags, and therefore provides a means of describing this temporal structure.
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Gimeno, i. Alquézar Joan. "Effective methods for recurrence solutions in delay differential equations." Doctoral thesis, Universitat de Barcelona, 2020. http://hdl.handle.net/10803/668438.
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This thesis deals with the jet transport for numerical integrators and
the effective invariant object computation of delay differential
equations.
Firstly we study how automatic differentiation (AD) affects when they
are applied to numerical integrators of ordinary differential
equations (ODEs). We prove that the use of AD is exactly the same as
considering the initial ODE and add new equations to the calculation
of the variational flow up to a certain order.
With this result we propose to detail the effective computation when
these equations are affected by a delay. In particular, the
computation of the stability of equilibrium points, the computation of
periodic orbits as well as their stability and continuation. Similarly
the computation of quasi-orbits periodic and its stability. For such
computations, we avoid the explicit generation of the Jacobian matrix
and we only require the matrix-vector evaluation.
Finally, we cover the existence, uniqueness and numerical computation
of the slowest direction of the stable manifold of a limit cycle of a
state-dependent delay equation differential. The results are
formulated in a posteriori format, which leads to rigorous proofs of
numerical experiments. Specifically our result is applicable when you
have a delayed perturbation and it depends on the state of an ODE in
the plane.
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Bennett, Deborah. "Applications of delay differential equations in physiology and epidemiology." Thesis, University of Surrey, 2005. http://epubs.surrey.ac.uk/842713/.
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The primary aim of this thesis has been to study examples of the application of delay differential equations to both physiology and epidemiology. As such, the thesis has two main strands. The physiological application is represented by mathematical models of the glucose-insulin interaction in humans. We provide a detailed introduction to recent and current literature associated with this area, together with an overview of the physiological processes involved. Two systems explicitly incorporating a discrete delay are proposed and positivity and boundedness of solutions to these models are established. Sufficient conditions for global stability of the steady state of both systems are derived using both Lyapunov methods and comparison principles. Physiological interpretations of the analysis are provided. The simpler of the two models is then extended to represent a person being given periodic infusions of both insulin and glucose. Positivity of solutions of this system is established and the existence of a positive periodic solution is proved using the coincidence degree theory method. The epidemiological application of delay differential equations is represented by mathematically modelling the transmission dynamics of tuberculosis. A brief overview of the current impact of the disease is given and some of the problems public health officials face in combatting it are discussed. A summary of work in the literature on this subject is provided. The effect of migration on the spread of tuberculosis is considered. Patch type models consisting of just two patches are proposed, each patch considered to be a country. We allow for the possibility that migration between two countries is often more one way than the other so diffusion is not the discrete analogue of Fickian diffusion. Conditions for both local and global stability of the disease-free steady state are determined using a variety of methods. A model with a continuous representation of space incorporating Fickian diffusion is then proposed. This is assumed to be more appropriate for various animal species than for humans. The possibility of a travelling wave-front solution is investigated and the minimum speed of such a solution is determined. Numerical simulations support these results. Finally the model is adapted to incorporate the tendency to move towards a focal point. Using numerical simulations, the effect of random dispersal and purposeful movement towards a focal point are investigated.
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Weedermann, Marion. "On perturbations of delay-differential equations with periodic orbits." Diss., Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/27972.
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Caberlin, Martin D. "Stiff ordinary and delay differential equations in biological systems." Thesis, McGill University, 2002. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=29416.
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The Santillan-Mackey model of the tryptophan operon was developed to characterize the anthranilate synthase activity in cultures of Escherichia coli. Similarly, the GABA reaction scheme was formulated to characterize the response of the GABAA receptor at a synapse, and the Hodgkin-Huxley model was developed to characterize the action potential of a squid giant axon. While the Hodgkin-Huxley model has been studied in great detail from a mathematical vantage, much less is known about the preceding two models in this regard. This work examines the stiffness of all three models; a novel perspective for both the Santillan-Mackey model and the GABA reaction. The characterization of the stiffness in these problems gives theoretical biologists insight into the dynamics of the reactions. It also enables them to select more computationally efficient methods for numerical simulations. The discovery of invariant manifolds in the Santillan-Mackey model and the GABA reaction in this work present experimentalists with concrete assays, against which the models can be tested.
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Zhuang, Dawei. "Stability analysis of stochastic differential delay equations with jumps." Thesis, Swansea University, 2011. https://cronfa.swan.ac.uk/Record/cronfa42955.
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Liu, Yunkang. "On functional differential equations with proportional delays." Thesis, University of Cambridge, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.364534.
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