Motivée par les travaux précédents sur la stabilisation de systèmes à excitation persistante, cette thèse s'intéresse à la stabilité et à la stabilisation de systèmes linéaires à commutation en dimensions finie et infinie. Après une introduction générale présentant les principales motivations et les résultats importants de la littérature, on aborde quatre sujets.On commence par l'étude d'un système linéaire en dimension finie à commutation aléatoire. Le temps passé en chaque sous-système $i$ est choisi selon une loi de probabilité ne dépendant que de $i$, les commutations entre sous-systèmes étant déterminées par une chaine de Markov discrète. On caractérise les exposants de Lyapunov en appliquant le Théorème Ergodique Multiplicatif d'Oseledets à un système associé en temps discret, et on donne une expression pour l'exposant de Lyapunov maximal. Ces résultats sont appliqués à un système de contrôle à commutation. Sous une hypothèse de contrôlabilité, on montre que ce système peut être stabilisé presque surement avec taux de convergence arbitraire, ce qui est en contraste avec les systèmes déterministes à excitation persistante.On considère ensuite un système de $N$ équations de transport avec amortissement interne à excitation persistante, couplées linéairement par le bord à travers une matrice $M$, ce qui peut être vu comme un système d'EDPs sur un réseau étoilé. On montre que, si l'activité de l'amortissement intermittent est déterminée par des signaux à excitation persistante, alors, sous des bonnes hypothèses sur $M$ et sur la rationalité des rapports entre les longueurs des arêtes du réseau, ce système est exponentiellement stable, uniformément par rapport aux signaux à excitation persistante. Ce résultat est montré grâce à une formule explicite pour les solutions du système, qui permet de bien suivre les effets de l'amortissement intermittent.Le sujet suivant que l'on considère est le comportement asymptotique d'équations aux différences non-autonomes. On obtient une formule explicite pour les solutions en termes des conditions initiales et de certains coefficients matriciels dépendants du temps, qui généralise la formule obtenue pour le système de $N$ équations de transport. Le comportement asymptotique des solutions est caractérisé à travers les coefficients matriciels. Dans le cas d'équations aux différences à commutation arbitraire, on obtient un résultat de stabilité qui généralise le critère de Hale--Silkowski pour les systèmes autonomes. Grâce à des transformations classiques d'EDPs hyperboliques en équations aux différences, on applique ces résultats au transport et à la propagation d'ondes sur des réseaux.Finalement, la formule explicite précédente est généralisée à une équation aux différences contrôlée, dont la contrôlabilité est alors analysée. La contrôlabilité relative est caractérisée à travers un critère algébrique sur les coefficients matriciels de la formule explicite, ce qui généralise le critère de Kalman. On compare également la contrôlabilité relative pour des retards différents en termes de leur structure de dépendance rationnelle, et on donne une borne sur le temps minimal de contrôlabilité. Pour des systèmes avec retards commensurables, on montre que la contrôlabilité exacte est équivalente à l'approchée et on donne un critère qui les caractérise. On analyse également la contrôlabilité exacte et approchée de systèmes en dimension $2$ avec deux retards sans l'hypothèse de commensurabilité. / Motivated by previous work on the stabilization of persistently excited systems, this thesis addresses stability and stabilization issues for linear switched systems in finite and infinite dimensions. After a general introduction presenting the main motivations and important results from the literature, we analyze four problems.The first system we study is a linear finite-dimensional random switched system. The time spend on each subsystem $i$ is chosen according to a probability law depending only on $i$, and the switches between subsystems are determined by a discrete Markov chain. We characterize the Lyapunov exponents by applying Oseledets' Multiplicative Ergodic Theorem to an associated discrete-time system, and provide an expression for the maximal Lyapunov exponent. These results are applied to a switched control system, showing that, under a controllability hypothesis, almost sure stabilization can be achieved with arbitrarily large decay rates, a situation in contrast to deterministic persistently excited systems.We next consider a system of $N$ transport equations with intermittent internal damping, linearly coupled by their boundary conditions through a matrix $M$, which can be seen as a system of PDEs on a star-shaped network. We prove that, if the activity of the intermittent damping terms is determined by persistently exciting signals, then, under suitable hypotheses on $M$ and on the rationality of the ratios between the lengths of the network edges, such system is exponentially stable, uniformly with respect to the persistently exciting signals. The proof of this result is based on an explicit representation formula for the solutions of the system, which allows one to efficiently track down the effects of the intermittent damping.The following topic we address is the asymptotic behavior of non-autonomous difference equations. We obtain an explicit representation formula for their solutions in terms of their initial conditions and some time-dependent matrix coefficients, which generalizes the one for the system of $N$ transport equations. The asymptotic behavior of solutions is characterized in terms of the matrix coefficients. In the case of difference equations with arbitrary switching, we obtain a stability result which generalizes Hale--Silkowski criterion for autonomous systems. Using classical transformations of hyperbolic PDEs into difference equations, we apply our results to transport and wave propagation on networks.Finally, we generalize the previous representation formula to a controlled difference equation, whose controllability is then analyzed. Relative controllability is characterized in terms of an algebraic property on the matrix coefficients from the explicit formula, generalizing Kalman criterion. We also compare the relative controllability for different delays in terms of their rational dependence structure, and provide a bound on the minimal controllability time. Exact and approximate controllability for systems with commensurable delays are characterized and proved to be equivalent. We also describe exact and approximate controllability for two-dimensional systems with two delays not necessarily commensurable.

El documento busca analizar el posible impacto del Fondo de Estabilización de los Precios de los Combustibles derivados del petróleo (FEPC) en variables macroeconómicas de interés, como el PBI, la inflación y la Deuda Pública. El punto fundamental del análisis es debido a la inestabilidad que generan las volatilidades de los precios internacionales del petróleo en economías dependientes del recurso, como la es el Perú. Además, de identificar si las herramientas de estabilización, como lo es el fondo, son ejecutadas de manera eficiente sin generar efectos adversos que puedan perjudicar otras aspectos de la economía. En el documento se encontraron evidencias empíricas sobre la finalidad de la estabilización de precios en diversos aspectos, así como el nacimiento de la necesidad de estos dependiendo de la situación del país frente a los recursos extractivos. Se hizo uso de un modelo de vectores de autocorrección (VAR), para estimar el efecto que poseen los diversos tipos de combustibles, haciendo uso de los precios internacionales y los establecidos por el FEPC. Se usaron datos mensuales para realizar la estimación, del periodo 2008-2018 y fueron extraídos del Banco Central de Reserva del Perú y del Organismo Supervisor de la Inversión en Energía y Minería. La síntesis de la investigación indico que el FEPC cumple con su función principal de ejecutar una estabilización de los precios de los combustibles, suavizando los choques externos a la economía peruana; sin embargo, se requieren realizar modificaciones en el fondo debido a efectos colaterales que lo hacen insostenible en el tiempo. / The developed document examines the impact of the Stabilization Fund for the prices of petroleum-derived fuels (FEPC, in Spanish) in macroeconomic variables of interest, such as GDP, inflation and public debt. The main reason for this study is due for the instability generated by volatilities in international oil prices in resource dependent economies, such as Peru. In addition, to identify if the stabilization tools, such as the fund, are executed efficiently without generating adverse effects that could harm other aspects of the economy. The document found empirical evidence on the purpose of price stabilization in various aspects, as well as the birth of their need depending on the country's situation with respect to extractive resources. A model of autocorrect vectors (VAR) was used to estimate the effect of various types of fuels, using international prices and those established by the FEPC. Monthly data were used to make the estimate, for the period 2008-2018 and were extracted from the Central Reserve Bank of Peru and the Supervisory Agency for Investment in Energy and Mining. The synthesis of the investigation indicated that the FEPC fulfills its main function of executing a stabilization of fuel prices, softening external shocks to the Peruvian economy, however, modifications to the fund are required due to collateral effects that they make it unsustainable over time. / Trabajo de investigación

The diploma thesis assesses the current state of the Hulín gravel and sand plant and pays attention to abrasions of severely damaged banks of the reservoir. With the help of the design of a suitable biotechnical stabilization, the receding of the shoreline in the section of interest will be prevented. The basis for the processing of appropriate bank stabilization proposals is the results achieved using a method of determining shore retreat. The individual developed variants of the bank remediation solution emphasize the use of vegetation support, especially suitable bank stands to ensure the stability of the banks and protection against abrasion.

As the Congolese conflict marks the 20th year, and the peace process 17 years, the apparent question is why is the search for peace in the DRC proving elusive? Spoilers and other impediments to the peace process in the DRC have been studied and UN peacekeepers have been operational in the country for nearly seventeen years, but the conflict continues. This study therefore seeks to understand the potential of UN peacekeeping to hinder the peace process in the DRC, and the United Nations Organization Stabilization Mission in the Democratic Republic of the Congo (MONUSCO) constitutes a study case. MONUSCO has been in operation for six years today succeeding the United Nations Organization Mission in the Democratic Republic of Congo (MONUC), and is still operating. Inasmuch as it looks early to gauge whether MONUSCO is contributing to progress or hindering the peace process in the DRC, this study focuses on the practices of UN peacekeepers under MONUSCO and their potential to delay peace initiatives. Using secondary data as the main source of information, i.e., books, articles, journals, news, UN reports and resolutions, triangulation and Game Theory, especially the Prisoners’ Dilemma Analytical Framework derived from the Prisoners’ Dilemma Game Matrix, this study finds that the Stabilization Mission is inconsistent, i.e., UN peacekeepers are performing controversial tasks: use of force to protect civilians, engaging in battles to neutralize armed militias and investigation of war crimes and human rights, tasks that have generated resentment from the FARDC/Kinshasa government and the armed militias, making the search for peace a one actors responsibility [MONUSCO’s task]. A clear indication that MONUSCO is hindering the peace process in the DRC. The thematic analysis details five (5) themes and indicates that; cooperation is problematic, use of force to protect civilians is controversial, there is a mismatch between doctrine and practice, i.e., deviation of UN peacekeeping from the basic principles, the justice dilemma, and an understanding of peace as absence of war and fighters. The thesis concludes that practices of MONUSCO need revisiting, dialogue should be encouraged, revision of peacekeeping principles and accurate timing of interventions, so as to enhance progress in the search for peace in DRC. / <p>This thesis is a true representation of my artistic academic work, written passiantely and informed with logical interpretation of other authors' perepectives, i.e., it is a deskstudy. It took me 10 weeks to produce this piece of work which adds to the ongoing debate on the Congolese process and UN peacekeeping in the DRC and other parts of the world. Written in Linnaeus University, Småland Sweden. </p> / Masters Thesis

Thesis. 1978. Sc.D.--Massachusetts Institute of Technology. Dept. of Civil Engineering. / Vita. / Bibliography: leaves 342-349. / Sc.D.

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第18519号 / 工博第3911号 / 新制||工||1601(附属図書館) / 31405 / 京都大学大学院工学研究科社会基盤工学専攻 / (主査)教授 白土 博通, 教授 宮川 豊章, 教授 八木 知己 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

京都大学 / 0048 / 新制・課程博士 / 博士(農学) / 甲第21277号 / 農博第2293号 / 新制||農||1062(附属図書館) / 学位論文||H30||N5141(農学部図書室) / 京都大学大学院農学研究科森林科学専攻 / (主査)教授 杉山 淳司, 教授 吉村 剛, 教授 渡邊 隆司, 教授 高妻 洋成 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DFAM

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