Equações diferenciais de quarta ordem aparecem naturalmente na modelagem de oscilações de estruturas elásticas, como aquelas observadas em pontes pênseis. São considerados dois modelos que descrevem as oscilações no tabuleiro de uma ponte. No modelo unidimensional estudamos blow up em espaço finito de soluções de uma classe de equações diferenciais de quarta ordem. Os resultados apresentados solucionam uma conjectura apresentada em [F. Gazzola and R. Pavani. Wide oscillation finite time blow up for solutions to nonlinear fourth order differential equations. Arch. Ration. Mech. Anal., 207(2):717752, 2013] e implicam a não existência de ondas viajantes com baixa velocidade de propagação em uma viga. No modelo bidimensional analisamos uma equação não local para uma placa longa e fina, suportada nas extremidades menores, livre nas demais e sujeita a protensão. Provamos existência e unicidade de solução fraca e estudamos o seu comportamento assintótico sob amortecimento viscoso. Estudamos ainda a estabilidade de modos simples de oscilação, os quais são classificados como longitudinais ou torcionais. / Fourth order differential equations appear naturally when modeling oscillations in elastic structures such as those observed in suspension bridges. Two models describing oscillations in the roadway of a bridge are considered. In the one-dimensional model we study finite space blow up of solutions for a class of fourth order differential equations. The results answer a conjecture presented in [F. Gazzola and R. Pavani. Wide oscillation finite time blow up for solutions to nonlinear fourth order differential equations. Arch. Ration. Mech. Anal., 207(2):717752, 2013] and imply the nonexistence of beam oscillation given by traveling wave profile with low speed propagation. In the two-dimensional model we analyze a nonlocal equation for a thin narrow prestressed rectangular plate where the two short edges are hinged and the two long edges are free. We prove existence and uniqueness of weak solution and we study its asymptotic behavior under viscous damping. We also study the stability of simple modes of oscillations which are classified as longitudinal or torsional.

Equações diferenciais de quarta ordem aparecem naturalmente na modelagem de oscilações de estruturas elásticas, como aquelas observadas em pontes pênseis. São considerados dois modelos que descrevem as oscilações no tabuleiro de uma ponte. No modelo unidimensional estudamos blow up em espaço finito de soluções de uma classe de equações diferenciais de quarta ordem. Os resultados apresentados solucionam uma conjectura apresentada em [F. Gazzola and R. Pavani. Wide oscillation finite time blow up for solutions to nonlinear fourth order differential equations. Arch. Ration. Mech. Anal., 207(2):717752, 2013] e implicam a não existência de ondas viajantes com baixa velocidade de propagação em uma viga. No modelo bidimensional analisamos uma equação não local para uma placa longa e fina, suportada nas extremidades menores, livre nas demais e sujeita a protensão. Provamos existência e unicidade de solução fraca e estudamos o seu comportamento assintótico sob amortecimento viscoso. Estudamos ainda a estabilidade de modos simples de oscilação, os quais são classificados como longitudinais ou torcionais. / Fourth order differential equations appear naturally when modeling oscillations in elastic structures such as those observed in suspension bridges. Two models describing oscillations in the roadway of a bridge are considered. In the one-dimensional model we study finite space blow up of solutions for a class of fourth order differential equations. The results answer a conjecture presented in [F. Gazzola and R. Pavani. Wide oscillation finite time blow up for solutions to nonlinear fourth order differential equations. Arch. Ration. Mech. Anal., 207(2):717752, 2013] and imply the nonexistence of beam oscillation given by traveling wave profile with low speed propagation. In the two-dimensional model we analyze a nonlocal equation for a thin narrow prestressed rectangular plate where the two short edges are hinged and the two long edges are free. We prove existence and uniqueness of weak solution and we study its asymptotic behavior under viscous damping. We also study the stability of simple modes of oscillations which are classified as longitudinal or torsional.

在這篇論文中，我們將考慮2個具有初值及邊界值的非線性波方程。首先，考慮一個具有某種阻尼項 (強阻尼、 線性阻尼及非線性阻尼) 的積分--微分方程。我們利用 Fadeo-Galerkin及 Contraction Mapping Principle的方法來建立局部存在性和唯一性，並且使用 Nako 的不等式 ([40]) 來討論解的長時間存在 (global existence) 及漸進行為( asymptotic behavior) 。至於在解的有限時間爆增 (finite time blow-up) 方面，我們使用直接方法 ([33]) 來探討具有強阻尼及線性阻尼的問題。另一方面，我們利用能量法 (energy method) 來討論非線性阻尼問題的有限時間爆增現象。其次，我們考慮一個具有特殊邊界值的 Kirchhoff方程， 我們利用擾動的能量法 (perturbed energy method) ([56]) 來研究解的漸進行為，並且使用直接方法 ([33]) 來探討解的有限時間暴增問題。最後，我們提出一些與本文相關的有趣問題以作為未來的研究。 / In this thesis, we shall consider two initial-boundary value problems for nonlinear wave equations. First, we consider a nonlinear integro- differential equation with some kind of damping terms - the strong damping term or the linear damping term or the nonlinear damping term. We establish the existence and uniqueness of local solutions by using Faedo-Galerkin method and Contraction Mapping Principle. We shall discuss the asymptotic behavior of global solutions by using Nako’s inequality ([40]). Moreover, the blow-up properties of local solutions with non-positive initial energy and small positive initial energy for strong or linear damping case are obtained by using direct method ([33]). On the other hand, for the nonlinear damping case, we apply the energy method to deduce the blow-up of local solutions with negative initial energy, vanishing initial energy and small positive initial energy. The estimates of lifespan of solutions are also given in each case. Secondly, we shall consider an initial-boundary value problem for a wave equation of Kirchhoff type with a linear boundary damping term. The asymptotic behavior of global solutions is investigated by using perturbed energy method ([56]). Moreover, the blow-up phenomena with the initial energy being non-positive and positive and the estimates for the blow-up time are obtained by direct approach ([33]). Finally, a list of some interesting problems related to our model is posed for further research.

Made available in DSpace on 2016-04-27T19:31:40Z (GMT). No. of bitstreams: 1 Valdemar Gomes de Souza Junior.pdf: 490610 bytes, checksum: 43c6d4b878c22488c3460164173c8809 (MD5) Previous issue date: 2007-11-09 / Fundação Ford / This work intends to contribute in the analysis of the paper of the press in the military blow of 1964. The brazilian historiography that produced a variety of research on the Military Blow of 1964, has a shortage of studies on the role of the press in the articulation of the coup. Despite the historiography recognize the importance of media activity in the conspiracy, which ensured unity within the rebel group and the support of the middle classes, it is only from the 1990 that began to appear scholarly works on media and the military coup. But still remains a subject little explored. In order to understand a little better the relationship between the press and the coup, chose the editorial of Folha de S. Paulo, produced between january 1963 and april 1964, as a source document for our study. This period follows the duration of the Goulart government under the presidential system and ends in the first month of the military dictatorship. The main objective of the research is to establish the connections between the constituent newspaper and the social forces that, under the tip of the bayonet, ended with a legitimately constituted government and at the same time recover the social function that the journal fulfilled. Far from recognizing the newspaper as a tool to verify facts and provide subsidies to interpretation, deep inside the newspaper to understand it as a producer of ideology and diffuser of a particular vision of the world. The research shows that the Folha de S. Paulo to adopt a responsible position in the editorial that the government Goulart, for its inability administration, the infiltration of communism in Brazil and the political crisis of the period, give legitimacy to military intervention, the coup brother / Este trabalho pretende contribuir na análise do papel da imprensa no golpe militar de 1964. Já que a historiografia brasileira, que produziu uma variedade de pesquisas a respeito do Golpe Militar de 1964, possui uma escassez de estudos sobre o papel da imprensa na articulação do golpe. Apesar da historiografia reconhecer a importância dos meios de comunicação na atividade conspiratória, que garantiu unidade no interior do grupo golpista e o apoio das classes médias, é somente a partir dos anos 1990 que começaram a aparecer trabalhos acadêmicos sobre mídia e o golpe militar. Porém, ainda continua sendo um tema pouco explorado. Com a finalidade de compreender um pouco melhor a relação entre a imprensa e o golpe, escolhemos os editoriais da Folha de S.Paulo, produzidos entre janeiro de 1963 e abril de 1964, como fonte documental para nosso estudo. Este período acompanha a duração do governo Goulart sob o regime presidencialista e termina no primeiro mês da ditadura militar. O objetivo principal da pesquisa é estabelecer os nexos constitutivos entre o jornal e as forças sociais que, sob a ponta da baioneta, acabaram com um governo legitimamente constituído e, ao mesmo tempo, recuperar a função social que o periódico cumpriu. Longe de reconhecer o jornal como simples instrumento para comprovar fatos e fornecer subsídios a interpretações mergulhamos no interior do jornal para compreendê-lo como produtor de ideologia e difusor de uma visão particular de mundo. A pesquisa demonstra que a Folha de S. Paulo ao adotar um posicionamento nos editoriais que responsabiliza o governo Goulart, por sua incapacidade administrativa, pela infiltração do comunismo no Brasil e pela crise política do período, dará legitimidade à intervenção militar, o golpe bonapartista

在這篇論文,我們考慮半線性微分方程式的初始邊界值問題之解u,的存在性,唯一性,和他的行為. (i) t^{-sigma}u''(t)=r_1u(t)^p+r_2u(t)^p(u'(t))^2, u(1)=u_0,u'(1)=u_1, 其中 p>1 為常數. 對t≥1,sigma>0,p>1 為偶數,r_1>0,r_2>0,u_0>0,u_1>0. 我們得到以下的結果.

Possible areas of improving the efficiencies of the Lincoln University flame weeder are identified and investigated. The Hoffmann burner initially used in the Lincoln University flame weeder was found not to entrain sufficient air to allow complete combustion of the LPG used. A new burner, the Modified Lincoln University burner, was designed to improve the entrainment of air. Results show that the new design entrained sufficient air to theoretically allow complete combustion of the LPG, and this resulted in a 22.7% increase in heat output per Kg of LPG used over the Hoffmann burner. Temperature x time exposure constants required to kill weeds 0 - 15, 15 - 30, and 30 - 45 mm in size, were found to be respectively 750, 882, and 989 degrees Celsius.Seconds. These constants can be used to calculate the maximum speed of travel an operator can use a flame weeder at, once the temperature profile underneath its shields are established at various travel speeds, and therefore ensure that the flame weeder is used at its maximum efficiency. The constants can also be used to establish the cost efficiency of any flame weeder (in $/Ha), depending on the size of the weeds to be treated. The materials and methods used in establishing the temperature x time exposure constants can be used to establish the temperature x time exposure constant of any weed species at any size.

<p>In the theory of holomorphic functions of one complex variable it is often useful to study subharmonic functions. The subharmonic can be described using the Laplace operator. When one studies holomorphic functions of several complex variables one should study the plurisubharmonic functions instead. Here the complex Monge--Ampère operator has a role similar to that of the Laplace operator in the theory of subharmonic functions. The complex Monge--Ampère operator is nonlinear and therefore it is not as well understood as the Laplace operator. We consider two types of boundary value problems for the complex Monge--Ampere equation in certain pseudoconvex domains. In this thesis the right-hand side in the Monge--Ampère equation will always be smooth, strictly positive and meet a monotonicity condition. The first type of boundary value problem we consider is a Dirichlet problem where we look for plurisubharmonic solutions which are zero on the boundary of the domain. We show that this problem has a unique smooth solution if the domain has a smooth bounded plurisubharmonic exhaustion function which is globally Lipschitz and has Monge--Ampère mass larger than one everywhere. We obtain some results on which domains have such a bounded exhaustion function. The second type of boundary value problem we consider is a boundary blow-up problem where we look for plurisubharmonic solutions which tend to infinity at the boundary of the domain. Here we also assume that the right-hand side in the Monge--Ampère equation satisfies a growth condition. We study this problem in strongly pseudoconvex domains with smooth boundary and show that it has solutions which are Hölder continuous with arbitrary Hölder exponent α, 0 ≤ α < 1. We also show a uniqueness result. A result on the growth of the solutions is also proved. This result is used to describe the boundary behavior of the Bergman kernel.</p>

In the theory of holomorphic functions of one complex variable it is often useful to study subharmonic functions. The subharmonic can be described using the Laplace operator. When one studies holomorphic functions of several complex variables one should study the plurisubharmonic functions instead. Here the complex Monge--Ampère operator has a role similar to that of the Laplace operator in the theory of subharmonic functions. The complex Monge--Ampère operator is nonlinear and therefore it is not as well understood as the Laplace operator. We consider two types of boundary value problems for the complex Monge--Ampere equation in certain pseudoconvex domains. In this thesis the right-hand side in the Monge--Ampère equation will always be smooth, strictly positive and meet a monotonicity condition. The first type of boundary value problem we consider is a Dirichlet problem where we look for plurisubharmonic solutions which are zero on the boundary of the domain. We show that this problem has a unique smooth solution if the domain has a smooth bounded plurisubharmonic exhaustion function which is globally Lipschitz and has Monge--Ampère mass larger than one everywhere. We obtain some results on which domains have such a bounded exhaustion function. The second type of boundary value problem we consider is a boundary blow-up problem where we look for plurisubharmonic solutions which tend to infinity at the boundary of the domain. Here we also assume that the right-hand side in the Monge--Ampère equation satisfies a growth condition. We study this problem in strongly pseudoconvex domains with smooth boundary and show that it has solutions which are Hölder continuous with arbitrary Hölder exponent α, 0 ≤ α &lt; 1. We also show a uniqueness result. A result on the growth of the solutions is also proved. This result is used to describe the boundary behavior of the Bergman kernel.

Oil well blow outs are investigated to determine methods to quickly and accurately respond to an emergency situation. Flow rate is needed to guide containment and dispersal operations. The Stratified Integral Multiphase Plume, SIMP, model was used to investigate the range of initial conditions available to integral modeling. Sensitivity to initial conditions is modest, but without experimental data at the appropriate scale the most accurate condition is unable to be determined. Flow rates are difficult to directly measure in blow out situations, so another method must be determined; therefore, sensitivity of several parameters to flow rate was also evaluated. Methane concentration in the first intrusion can be used in conjunction with velocity and trap height measurements to determine flow rate using an integral model. Plume width and temperature were determined to have little sensitivity. Separately, a containment dome was tested in the laboratory to determine if a full scale dome can be used to contain an oil leak in the field. The dome was found to have satisfactory entrapment in the designed position.

On étudie l'existence de 'blow-up' et l'ensemble des points de 'blow-up' pour une équation de type chaleur dégénérée ou non avec un terme source uniforme fonction non linéaire de la température instantanée en un point fixé du domaine. L'étude est conduite par les méthodes d'analyse classique (fonction de Green, développements en fonctions propres, principe du maximum) ou fonctionnelle (semi-groupes d'opérateurs linéaires).