Resumo: Este artigo aborda as manifestações da precarização do trabalho como uma nova e complexa questão social. Procuramos descrever as dimensões humanas implicadas nesse processo de trabalho, traduzindo o nível de exploração de suas relações precárias. Dentre os resultados, destaca-se a relação que esses trabalhadores fizeram de seus sintomas de saúde com seu vínculo de trabalho. A relação precária de trabalho associada à baixa remuneração pode ter manifestações físicas de insônia e medo, refletindo a perda da autoestima. Discutimos a atual reorganização social da produção, em virtude da crise e reestruturação do capitalismo, no último quartel do século XX, que repercutiu no mundo do trabalho, desordenando as relações que conformaram o Estado de Bem-Estar Social e reordenando-as sob a égide da regulação pelo mercado. Concluímos que o trabalhador, frente à sua relação precária de trabalho, tem como preocupação central a ausência de garantias sociais, e suas consequências no longo prazo, quando não mais será útil a esse modelo de exploração da força de trabalho. A pesquisa foi realizada junto a 112 trabalhadores terceirizados por cooperativa, lotados no Serviço de Enfermagem de uma unidade pública de saúde localizada na cidade do Rio de Janeiro, vinculada ao Ministério da Saúde. Palavras-chave: Trabalho; precarização; saúde do trabalhador; neoliberalismo; Estado de Bem-Estar Social.
The problem of water entry of wedges represents one of the most classic research topics in fluid mechanics. Along the past decades, many different analytical methods have been proposed to calculate pressure distribution and peak loads during the water entry, such as Wagner (1932) and Dobrovol’skaya (1969). Zhao and Faltinsen (1993) and Mei (1995) present numerical solutions based on potential theory assumptions (inviscid, irrotational and incompressible flow). For more complex geometries and cases these methods might not be accurate enough due to the simplifications assumed, and in these cases the use of computational fluid dynamics (CFD) might be an interest tool to provide more accurate analysis.
This work presents CFD results for different conditions of water entry of 2D wedges. The simulations were performed with a marine dedicated flow solver, FINE™/Marine from NUMECA, which features an unsteady Reynolds-averaged Navier-Stokes (URANS) solver and a finite volume method to perform spatial discretization. The multiphase flow is represented through the Volume of Fluid (VOF) method for incompressible and nonmiscible fluids. Different water entry conditions are explored. The effect of the mesh size, time step and other setup parameters over the results are discussed for simulations with 2D wedges to extend to other studies of water impact. The wedge velocity and hydrodynamic pressure distribution along the model’s face are monitored during the water entry and compared to experimental data from previous publication (Yettou et al, 2006) for water entry of wedges during free fall.
When under influence of an incident wave system, any freely floating body presents a general motion with all six degrees of freedom. The Instantaneous Center of Rotation, as defined in classical mechanics, is a concept that allows the description of a general motion in 6 degrees of freedom as a pure rotation around such point. This approach, although not widely used in ocean engineering, might be an alternative tool that allows fast and precise analysis in many cases. Recent studies have shown that under specific conditions, such as a heading wave condition, the ICR varies in time but it is always located along a line for one wave frequency. Similar results were presented regarding beam waves as well.
The present work continues with the investigation regarding the behavior of ICR under more generic conditions, assuming oblique waves exciting a vessel with typical geometry of a FPSO platform. The study extends the knowledge derived based on 2D approaches from previous works, comparing the results obtained from the different methods. An analytical model is presented, assuming only harmonic motion to all 6 degrees of freedom and showing that, similar to what was observed in the simplified 2D cases, the ICR tends to present dependence on the frequency of motion. Numerical data acquired from commercial codes based on potential theory is also presented.
A non-linear mathematical model is presented for the Equation of Motion of the Water Column inside circular cylindrical structures in different cases, comparing to previous models in literature. Experimental model tests were carried out investigating the water column decay under given initial conditions, and an analysis is performed for each cycle showing the dynamic behaviour of OWC evolving in time. The results show asymmetric pattern in the time series acquired in the decay tests as a consequence of variations of the Added Length and quadratic viscous damping as the direction of the flow changes, as observed in previous studies.
A general procedure is proposed to assess the unknown parameters including the quadratic damping viscous coefficients through the concept of “equivalent linear harmonic” as a linearisation of such terms, enlightening its dependence on the motion amplitude as well as the water column draft.
Experimental data for the OWC response under a set of incoming regular waves is also presented, comparing the results to numerical simulation through a solver based on the estimation of the damping coefficients obtained in the decay tests.
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