Fundação Carlos Chagas Filho de Amparo a Pesquisa do Estado do Rio de Janeiro / The Amazon river, located in northernBrazil, discharges between 80,000 and 250,000 m3s-1 of water onto the adjacent shelf, creating a plume of brackish water that extends hundreds of kilometers away from the river mouth. This river also carries a large amount of fine sediments to the ocean where fluid mud has been found in the topset and upper foreset layers of the subaqueous delta formed on the mid-shelf. One of the main goals of this dissertation is to describe how turbulence and suspended sediment concentration vary along the Northern Channel of the Amazon river. Water column measurements were carried out in October 2008 at six anchor stations (P1, P3, P5, P6, P8 e P9) located seaward of the river mouth; P1 and P9 were 125 km apart. Each station was occupied during 13 hours during which current speed and direction were continuously sampled with a 600 kHz Teledyne-RDI ADCP; hourly profiles of temperature, salinity, turbidity and depth were also obtained. Water samples were collected for determination of Suspended Particulate Matter (SPM) concentration and calibration of the turbidity sensor. Current speed reached values above 1.5 m s1 in the along-channel direction (NE-SW); a remarkable ebb-flood asymmetry was observed and flows were strongly ebb-dominated. Throughout the water column, SPM concentration at stations P1 and P3 varied between 100 and 300 mg L1 in association with the presence of freshwater. In contrast, a strong salinity gradient was observed between stations P6 and P9, coinciding with the occurrence of concentrations of SPM above 10 g L-1 (fluid mud). At stations P3, P5 and P6, interface between freshwater from the Amazon river and salt water from the continental shelf, shear stresses wereestimated through four diferents methods: Reynolds, Turbulent Kinetic Energy (TKE), modified TKE and Quadratic Law; in the nearbed region (3 mab) the computed values varied between 0 and 3 Pa. At the three stations (P3, P5 and P6) the lowest and the highest shear stress values were obtained through, respectively, the Reynolds and the TKE methods. Over the whole water column turbulence intensity was estimated through the standard deviation of the turbulent component of the along-channel current velocity (root-mean square of u); from these values, it was estimated the turbulent dissipation of energy (G), whose values at 3 mab varied between zero and 20 s1.

<p>We construct two independent hierarchies of&nbsp;moment equations and we apply the maximum&nbsp;entropy principle for polyatomic gases. We&nbsp;formulate multivelocity and multitemperature&nbsp;model of Eulerian polyatomic gases starting from&nbsp;kinetic theory, that is compared in the&nbsp;neighborhood of global equilibrium state to the&nbsp;models based on extended thermodynamics. We&nbsp;analyze diffusion asymptotics of the Boltzmann&nbsp;<br />equations for mixtures of monatomic gases.</p> / <p>Конструишу се две независне хијерархије<br />једначина момената и примењује се принцип<br />максимума ентропије за вишеатомске гасове.<br />Формира се вишебрзински и вишетемпературни<br />модел Ојлерових вишеатомских гасова полазећи<br />од кинетичке теорије и добијени модел се<br />пореди у околини стања глобалне равнотеже са<br />моделом проширене термодинамике. Анализира<br />се дифузиона асимптотика Болцманових<br />једначина за мешавине једноатомских гасова.</p> / <p>Konstruišu se dve nezavisne hijerarhije<br />jednačina momenata i primenjuje se princip<br />maksimuma entropije za višeatomske gasove.<br />Formira se višebrzinski i višetemperaturni<br />model Ojlerovih višeatomskih gasova polazeći<br />od kinetičke teorije i dobijeni model se<br />poredi u okolini stanja globalne ravnoteže sa<br />modelom proširene termodinamike. Analizira<br />se difuziona asimptotika Bolcmanovih<br />jednačina za mešavine jednoatomskih gasova.</p>