Cálculo de coeficientes de arrasto para satélites artificiais

Pós-graduação em Física - FEG

Estudo numérico de modelos de arrasto e do coeficiente de restituição no escoamento gás-sólido em leito fluidizado

Pós-graduação em Engenharia Mecânica - FEG

Estudo de manobras evasivas com perturbações orbitais

Pós-graduação em Física - FEG

Estimativa da captura total de peixe e camarão das pescarias de emalhe e de arrasto da Baía de Maputo, em 1985

The most important fisheries of Maputo Bay (Mozambique) are the gill netting of the Hilsa kelee and the trawling of the shrimps Penaeus indicus and Metapenaeus monoceros . Data of capture and yields are presented and the number of artisanal fishing boats and semi-industrial fishing vessels is given.

Pesca de Arrasto e Linha na Baia de Inhambane: 1998

The fishing activity in Inhambane Bay is still strictly artisanal, with predominance of trawl and line fishing among other methods. Trawl fishing in particular, is considered to be the most important fishing method in terms of revenue and potential for the future.

Actividade de pesca de emalhe e de arrasto na Baía de Maputo em 1984

The main goal of this paper is to determine the total catch of fish and shrimp made by driftnet fleet and trawling in Maputo Bay in 1984. This estimate is rather primitive in relation to artisanal fisheries. Fishermen show a lack of motivation for registration and data transmition (mainly due to a lack of mobilization and awareness). Then the quality of data is low and the informative system is not effective. The study is based on records of several organizations (Sulpesca, the Maritime Administration of Maputo, Maputo Fisheries Service) and enriched with information collected by samplers of the Instituto de Investigação Pesqueira of Maputo.

Recolha de camarões reprodutores vivos da espécie Fenneropenaeus indicus da pesca de arrasto semi-industrial na Baía de Maputo

The collection of wild breeders of the Indian white prawn Fenneropenaeus indicus from two semi-industrial trawlers fishing in Maputo Bay is assessed for the period between August and November 1993. The daily mean catch (12-21 prawns dayˉ¹) increased until October but monthly yields were not significantly different (P>0.05). The monthly mean mortality ranged between 8% and 20% and was similar for males and females. More than 70% of the catch comprised small (grade B1: 20-39 g) and medium size (grade B2: 40-59 g) prawns. While males were exclusively of grade B1 (99%), the females were predominantly of grades B2 and B3 (60-80 g). The collection of larger breeders (grade B4: >80 g) was low and represented only 1% of total catches and a maximum of 3% of females. The net profit of breeders collection increased with size (grade) of prawns, and represented a maximum yield of 114% for grade B3. The added value of live prawns exceeded 450% of the cost to the fisherman, but decreased with size of breeders. It is considered that the semi-industrial trawling fishery operating in Maputo Bay has potential for supplying wild breeders of the Indian white prawn for aquaculture. This activity can also contribute to value adding of part of the catch traditionally destined for human consumption.

Quantificação das capturas acessórias e rejeições de arrasto de crustáceos na costa do Algarve

Dissertação mest., Biologia Marinha, Universidade do Algarve, 2009

Simulação de fluxo de fluidos em meios porosos desordenados uma análise de efeito de escala na estimativa da permeabilidade e do coeficiente de arrasto

The present study provides a methodology that gives a predictive character the computer simulations based on detailed models of the geometry of a porous medium. We using the software FLUENT to investigate the flow of a viscous Newtonian fluid through a random fractal medium which simplifies a two-dimensional disordered porous medium representing a petroleum reservoir. This fractal model is formed by obstacles of various sizes, whose size distribution function follows a power law where exponent is defined as the fractal dimension of fractionation Dff of the model characterizing the process of fragmentation these obstacles. They are randomly disposed in a rectangular channel. The modeling process incorporates modern concepts, scaling laws, to analyze the influence of heterogeneity found in the fields of the porosity and of the permeability in such a way as to characterize the medium in terms of their fractal properties. This procedure allows numerically analyze the measurements of permeability k and the drag coefficient Cd proposed relationships, like power law, for these properties on various modeling schemes. The purpose of this research is to study the variability provided by these heterogeneities where the velocity field and other details of viscous fluid dynamics are obtained by solving numerically the continuity and Navier-Stokes equations at pore level and observe how the fractal dimension of fractionation of the model can affect their hydrodynamic properties. This study were considered two classes of models, models with constant porosity, MPC, and models with varying porosity, MPV. The results have allowed us to find numerical relationship between the permeability, drag coefficient and the fractal dimension of fractionation of the medium. Based on these numerical results we have proposed scaling relations and algebraic expressions involving the relevant parameters of the phenomenon. In this study analytical equations were determined for Dff depending on the geometrical parameters of the models. We also found a relation between the permeability and the drag coefficient which is inversely proportional to one another. As for the difference in behavior it is most striking in the classes of models MPV. That is, the fact that the porosity vary in these models is an additional factor that plays a significant role in flow analysis. Finally, the results proved satisfactory and consistent, which demonstrates the effectiveness of the referred methodology for all applications analyzed in this study.

Bioecologia da ictiofauna marinha descartada pelo arrasto camaroeiro em praias da Bacia Potiguar, Brasil

The composition of ichthyofauna discarded by trawling shrimping, their reproductive status and feeding ecology were studied on the beaches of Basin Rio Grande do Norte, Brazil. Fish were collected monthly in the year of 2012. During biometrics, portions of the digestive tract and of gonads were removed, fixed in formalin 10% and Bouin, respectively, for be submitted to histological processing by the techniques of hematoxylin-eosin. Stomach content analyzes were performed using the methods of Frequency of Occurrence and Volumetric and was calculated the repletion index. Throughout the study period were recorded a total of 49 species. The fish assemblages differed between sections monitoring, with the highest abundance, biomass and indices of richness and diversity in sections B, D and C. Already the excerpt A, showed higher values for dominance and equitability. In the cluster analysis according to the faunal similarity was observed the formation of three groups: group I formed by excerpts B and D, group II by excerpt C and group III formed by excerpt A. The assessment of reproductive stage revealed that the fish assemblages discarded by trawling are composed mainly of juveniles. Regarding the feeding ecology, the species Larimus breviceps, Menticirrhus littoralis and Pomadasys corvinaeformis characterized as carnivorous with tendency to carcinofagia. Already Conodon nobilis characterized as carnivorous with tendency to piscivory, but all proved generalist-opportunistic with increase of feeding activity during drought. The dendrogram of grouping of the species developed based on the food items used shows the formation of four groups: Group I consists of species that feed mainly of "gastropod" and "sediment"; group II of "teleost fish"; the group III of "crustacea" and group IV of "echinodermata" and "bivalve". The anatomical and histological characteristics of the digestive tract were consistent with the dietary habits of the analyzed species. In this context, the Costa Branca of Rio Grande do Norte can be considered a feeding site and recruitment for juveniles, which, opportunistically, utilize resources associated with the background

Conseqüencias do arrasto viscoso no modelo Fermi-Ulam

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Dissipação via arrasto viscoso como mecanismo de supressão da aceleração de Fermi no bilhar elíptico-ovoide com fronteira dependente do tempo

Pós-graduação em Física - IGCE

Interação de tartarugas marinhas com a pesca de arrasto de fundo de camarão no municipío de Ubatuba-SP

Não disponível

Captura gravitacional de pequenos corpos por arrasto em um gás modelado usando equações hidrodinâmicas

In this work we have developed an apparatus in order to study the capture of asteroids by planets surrounded by a gas envelope during y-by, to do this we have brought an innovation by using a hydrodynamical gas. We began such project by studying particles trajectories with a code based on the analytical gas. After being used to this model we have started a process to elaborate a code which uses the gas in a numerical way. The hydrodynamical gas is described by equations which are not solved analytically. Therefore, it was used an algorithm able to model the gas by keeping all information of the gas in cells. Thus we have made a code to read such cell`s information and then to solve all calculations. Once this process is done, the program inform us all date about the simulated trajectories