A dinâmica da atual conjuntura econômica brasileira

Mostra os resultados da política fiscal do governo que poderão demandar mais tempo do que o desejável e que, dificilmente, a economia brasileira escapará de um quadro recessivo em 2016, ao contrário do que imagina o Governo.

Dinâmica da política de saúde na Nova República

Analisa a dinâmica política entre atores do Legislativo e do Executivo federal na Nova República, a partir de dispositivos sobre políticas de saúde inseridos na Constituição de 1988, os quais tentaram estabelecer uma conexão normativa com a legislação que seria necessária à implantação do sistema de saúde.

Modelo de dinámica de sistemas para la implantación de tecnologías de la información en la gestión estratégica universitaria

394 p.

Numerical simulation of a single fluid particle rising in non-Newtonian fluids

In this work, a level set method is developed for simulating the motion of a fluid particle rising in non-Newtonian fluids described by generalized Newtonian as well as viscoelastic model fluids. As the shear-thinning model we use a Carreau-Yasuda model, and the viscoelastic effect can be modeled with Oldroyd-B constitutive equations. The control volume formulation with the SIMPLEC algorithm incorporated is used to solve the governing equations on a staggered Eulerian grid. The level set method is implemented to compute the motion of a bubble in a Newtonian fluid as one of typical examples for validation, and the computational results are in good agreement with the reported experimental data．The level set method is also applied for simulating a Newtonian drop rising in Carreau-Yasuda and Oldroyd-B fluids．Numerical results including noticeably negative wake behind the drop and viscosity field are obtained, and compare satisfactorily with the known literature data.

Investigation on average void fraction for air/non-Newtonian power-law fluids two-phase flow in downward inclined pipes

The present work has been carried out to investigate on the average void fraction of gas/non-Newtonian fluids flow in downward inclined pipes. The influences of pipe inclination angle on the average void fraction were studied experimentally. A simple correlation, which incorporated the method of Vlachos et al. for gas/Newtonain fluid horizontal flow, the correction factor of Farooqi and Richardson and the pipe inclination angle, was proposed to predict the average void fraction of gas/non-Newtonian power-law stratified flow in downward inclined pipes. The correlation was based on 470 data points covering a wide range of flow rates for different systems at diverse angles. A good agreement was obtained between theory and data and the fitting results could describe the majority of the experimental data within ±20%.

Dinâmica populacional de Halodule wrightii Ascherson e sua fauna e flora associada em Cabo Frio RJ

Fanerógamas marinhas (gramas marinhas) são plantas com flores adaptadas ao ambiente marinho costeiro da maioria dos continentes do mundo. As gramas marinhas formam extensos bancos e proveem valiosos recursos em águas costeiras rasas em todo o mundo, servindo de alimento e berçário para espécies importantes de pescados comerciais e recreacionais. Nesse estudo foi realizada uma revisão sobre o estado de conhecimento das fanerógamas marinhas no Brasil até o presente momento; avaliou-se a importância do monitoramento em longo prazo e a influência de fatores ambientais, como o número de manchas solares; pesquisou-se também a distribuição espacial da grama marinha, bem como a fauna e flora associada; e o crescimento de Halodule wrightii em duas condições ambientais extremas (exposta no ciclo de maré baixa e permanentemente submersa). A revisão bibliográfica sobre as gramas marinhas foi abrangente e verificou a existência de algumas lacunas no conhecimento. Através do monitoramento a longo prazo pôde ser observado que o número de manchas solares tem forte relação negativa sobre a altura do dossel das gramas marinhas de região entre marés. A variação de marés na região de mediolitoral está relacionada diretamente com a distribuição espacial de Halodule wrightii e, consequentemente na distribuição da fauna e flora associada. A diferença de crescimento nos eixos de Halodule wrightii em condições ambientais diferentes é compensada pelas variações nas características de distribuição da planta no ambiente, tais como a altura do dossel, a densidade e biomassa de eixos. O monitoramento a longo prazo pode permitir a tomada de ações que auxiliem no manejo e na recuperação desses importantes habitats costeiros.

Dinâmica de crescimento de Cedrela odorata L. (Meliaceae) na Floresta Atlântica do Estado do Rio de Janeiro: fenologia, atividade cambial e dendrocronologia

Ao longo do século XX, poucos estudos de dendrocronologia foram desenvolvidos com espécies de ambientes tropicais, em função da crença de que as condições climáticas nessas regiões não apresentavam variações suficientemente marcantes e regulares para induzir um ritmo anual de crescimento radial. A realização de trabalhos sobre esse tema nas últimas décadas revelou que a formação de anéis de crescimento anuais nos trópicos pode estar associada a fatores diversos, como: existência de estação seca bem definida, ocorrência de inundações sazonais, respostas ao comportamento fenológico, respostas ao fotoperíodo e a ritmos endógenos. O presente estudo tem por objetivo compreender a dinâmica de crescimento radial de uma espécie da Mata Atlântica se desenvolvendo em ambiente natural. Para tanto, propôs-se: i) investigar a periodicidade da atividade cambial e dos fatores que a influenciam; ii) estimar a idade e taxa de crescimento diamétrico e iii) correlacionar os fatores ambientais com os anéis de crescimento, em indivíduos de Cedrela odorata L. Para o estudo da atividade cambial, foram obtidas amostras de caule a 1,30 m do solo, contendo periderme, faixa cambial e xilema e floema secundários, por métodos não destrutivos. A fenologia vegetativa e a frutificação dos indivíduos amostrados foram acompanhadas durante todo o período do experimento. O material coletado foi processado segundo técnicas usuais em Anatomia Vegetal e analisado sob microscopia óptica e de fluorescência. Os dados de fotoperíodo, precipitação, temperatura e fenologia vegetativa foram correlacionados à atividade cambial. Para o estudo dos anéis de crescimento, as coletas também foram realizadas a 1,30 m do solo, por meio de sonda de Pressler. As amostras obtidas foram polidas e analisadas sob microscópio estereoscópio, para demarcação e aferição do número de anéis de crescimento, e a largura dos anéis foi mensurada para a determinação das taxas de crescimento radial. A série histórica de temperatura e precipitação foi correlacionada à cronologia dos anéis de crescimento. Os resultados indicaram que a atividade cambial segue um ritmo anual de crescimento, correlacionado à sazonalidade do fotoperíodo, da precipitação e da fenologia vegetativa. A análise dos anéis de crescimento permitiu estimar a idade dos indivíduos e determinar a taxa média de incremento e as taxas de incremento diamétrico acumulado e incremento médio anual para a espécie no sítio de estudo. Os dados de incremento radial evidenciaram a ausência de relação entre a idade e o diâmetro das árvores. A análise da variação na largura dos anéis não apresentou correlações significativas com os fatores climáticos analisados.

Kinetic theory of normal quantum fluids

Close to equilibrium, a normal Bose or Fermi fluid can be described by an exact kinetic equation whose kernel is nonlocal in space and time. The general expression derived for the kernel is evaluated to second order in the interparticle potential. The result is a wavevector- and frequency-dependent generalization of the linear Uehling-Uhlenbeck kernel with the Born approximation cross section.

The theory is formulated in terms of second-quantized phase space operators whose equilibrium averages are the n-particle Wigner distribution functions. Convenient expressions for the commutators and anticommutators of the phase space operators are obtained. The two-particle equilibrium distribution function is analyzed in terms of momentum-dependent quantum generalizations of the classical pair distribution function h(k) and direct correlation function c(k). The kinetic equation is presented as the equation of motion of a two -particle correlation function, the phase space density-density anticommutator, and is derived by a formal closure of the quantum BBGKY hierarchy. An alternative derivation using a projection operator is also given. It is shown that the method used for approximating the kernel by a second order expansion preserves all the sum rules to the same order, and that the second-order kernel satisfies the appropriate positivity and symmetry conditions.

Análise de fadiga em pontes rodoviárias de concreto armado

As pontes rodoviárias de concreto armado estão sujeitas às ações dinâmicas variáveis devido ao tráfego de veículos sobre o tabuleiro. Estas ações dinâmicas podem gerar o surgimento das fraturas ou mesmo a sua propagação na estrutura. A correta consideração destes aspectos objetivou o desenvolvimento de um estudo, de forma a avaliar os esforços do tráfego de veículos pesados sobre o tabuleiro. As técnicas para a contagem de ciclos de esforços e a aplicação das regras de dano acumulado foram analisadas através das curvas S-N de diversas normas estudadas. A ponte rodoviária investigada é constituída por quatro vigas longitudinais, três transversinas e por um tabuleiro de concreto armado. O modelo computacional, desenvolvido para a análise dinâmica da ponte, foi concebido com base no emprego de técnicas usuais de discretização através do método dos elementos finitos. O modelo estrutural da obra de arte rodoviária estudada foi simulado com base no emprego de elementos finitos sólidos tridimensionais. Os veículos são representados a partir de sistemas massa-mola-amortecedor. O tráfego dessas viaturas é considerado mediante a simulação de comboios semi-infinitos, deslocando-se com velocidade constante sobre o tabuleiro da ponte. As conclusões deste trabalho versam acerca da vida útil de serviço dos elementos estruturais de pontes rodoviárias de concreto armado submetidas às ações dinâmicas provenientes do tráfego de veículos pesados sobre o tabuleiro.

Full and Model-Reduced Structure-Preserving Simulation of Incompressible Fluids

This thesis outlines the construction of several types of structured integrators for incompressible fluids. We first present a vorticity integrator, which is the Hamiltonian counterpart of the existing Lagrangian-based fluid integrator. We next present a model-reduced variational Eulerian integrator for incompressible fluids, which combines the efficiency gains of dimension reduction, the qualitative robustness to coarse spatial and temporal resolutions of geometric integrators, and the simplicity of homogenized boundary conditions on regular grids to deal with arbitrarily-shaped domains with sub-grid accuracy.

Both these numerical methods involve approximating the Lie group of volume-preserving diffeomorphisms by a finite-dimensional Lie-group and then restricting the resulting variational principle by means of a non-holonomic constraint. Advantages and limitations of this discretization method will be outlined. It will be seen that these derivation techniques are unable to yield symplectic integrators, but that energy conservation is easily obtained, as is a discretized version of Kelvin's circulation theorem.

Finally, we outline the basis of a spectral discrete exterior calculus, which may be a useful element in producing structured numerical methods for fluids in the future.

A molecular dynamics study of the microscopic properties of simple dense fluids

The microscopic properties of a two-dimensional model dense fluid of Lennard-Jones disks have been studied using the so-called "molecular dynamics" method. Analyses of the computer-generated simulation data in terms of "conventional" thermodynamic and distribution functions verify the physical validity of the model and the simulation technique.

The radial distribution functions g(r) computed from the simulation data exhibit several subsidiary features rather similar to those appearing in some of the g(r) functions obtained by X-ray and thermal neutron diffraction measurements on real simple liquids. In the case of the model fluid, these "anomalous" features are thought to reflect the existence of two or more alternative configurations for local ordering.

Graphical display techniques have been used extensively to provide some intuitive insight into the various microscopic phenomena occurring in the model. For example, "snapshots" of the instantaneous system configurations for different times show that the "excess" area allotted to the fluid is collected into relatively large, irregular, and surprisingly persistent "holes". Plots of the particle trajectories over intervals of 2.0 to 6.0 x 10^-12 sec indicate that the mechanism for diffusion in the dense model fluid is "cooperative" in nature, and that extensive diffusive migration is generally restricted to groups of particles in the vicinity of a hole.

A quantitative analysis of diffusion in the model fluid shows that the cooperative mechanism is not inconsistent with the statistical predictions of existing theories of singlet, or self-diffusion in liquids. The relative diffusion of proximate particles is, however, found to be retarded by short-range dynamic correlations associated with the cooperative mechanism--a result of some importance from the standpoint of bimolecular reaction kinetics in solution.

A new, semi-empirical treatment for relative diffusion in liquids is developed, and is shown to reproduce the relative diffusion phenomena observed in the model fluid quite accurately. When incorporated into the standard Smoluchowski theory of diffusion-controlled reaction kinetics, the more exact treatment of relative diffusion is found to lower the predicted rate of reaction appreciably.

Finally, an entirely new approach to an understanding of the liquid state is suggested. Our experience in dealing with the simulation data--and especially, graphical displays of the simulation data--has led us to conclude that many of the more frustrating scientific problems involving the liquid state would be simplified considerably, were it possible to describe the microscopic structures characteristic of liquids in a concise and precise manner. To this end, we propose that the development of a formal language of partially-ordered structures be investigated.

The instability of fluids with time dependent heating

The stability of a fluid having a non-uniform temperature stratification is examined analytically for the response of infinitesimal disturbances. The growth rates of disturbances have been established for a semi-infinite fluid for Rayleigh numbers of 10³, 10⁴, and 10⁵ and for Prandtl numbers of 7.0 and 0.7.

The critical Rayleigh number for a semi-infinite fluid, based on the effective fluid depth, is found to be 32, while it is shown that for a finite fluid layer the critical Rayleigh number depends on the rate of heating. The minimum critical Rayleigh number, based on the depth of a fluid layer, is found to be 1340.

The stability of a finite fluid layer is examined for two special forms of heating. The first is constant flux heating, while in the second, the temperature of the lower surface is increased uniformly in time. In both cases, it is shown that for moderate rates of heating the critical Rayleigh number is reduced, over the value for very slow heating, while for very rapid heating the critical Rayleigh number is greatly increased. These results agree with published experimental observations.

The question of steady, non-cellular convection is given qualitative consideration. It is concluded that, although the motion may originate from infinitesimal disturbances during non-uniform heating, the final flow field is intrinsically non-linear.

Turbulent buoyant jets into stratified or flowing ambient fluids

Theoretical and experimental studies were made on two classes of buoyant jet problems, namely:

1) an inclined, round buoyant yet in a stagnant environment with linear density-stratification;

2) a round buoyant jet in a uniform cross stream of homogenous density.

Using the integral technique of analysis, assuming similarity, predictions can be made for jet trajectory, widths, and dilution ratios, in a density-stratified or flowing environment. Such information is of great importance in the design of disposal systems for sewage effluent into the ocean or waste gases into the atmosphere.

The present study of a buoyant jet in a stagnant environment has extended the Morton type of analysis to cover the effect of the initial angle of discharge. Numerical solutions have been presented for a range of initial conditions. Laboratory experiments were conducted for photographic observations of the trajectories of dyed jets. In general the observed jet forms agreed well with the calculated trajectories and nominal half widths when the value of the entrainment coefficient was taken to be α = 0.082, as previously suggested by Morton.

The problem of a buoyant jet in a uniform cross stream was analyzed by assuming an entrainment mechanism based upon the vector difference between the characteristic jet velocity and the ambient velocity. The effect of the unbalanced pressure field on the sides of the jet flow was approximated by a gross drag term. Laboratory flume experiments with sinking jets which are directly analogous to buoyant jets were performed. Salt solutions were injected into fresh water at the free surface in a flume. The jet trajectories, dilution ratios and jet half widths were determined by conductivity measurements. The entrainment coefficient, α, and drag coefficient, C_d, were found from the observed jet trajectories and dilution ratios. In the ten cases studied where jet Froude number ranged from 10 to 80 and velocity ratio (jet: current) K from 4 to 16, α varied from 0.4 to 0.5 and C_d from 1.7 to 0.1. The jet mixing motion for distance within 250D was found to be dominated by the self-generated turbulence, rather than the free-stream turbulence. Similarity of concentration profiles has also been discussed.