Diversidade de cefalópodes e o seu papel no nicho trófico de seus principais predadores nos Arquipélagos de Fernando de Noronha e São Pedro e São Paulo

This study aims, to characterize the diversity of cephalopods by analyzing the stomach contents of fishes caught in the islands of St. Peter and St. Paul (ASPSP) and Fernando de Noronha (AFN). Also, verify the participation of cephalopods in the diet of their main predators. A total of 723 stomachs were collected, from 8 species of fish, caught by the fishery, 471 stomachs were from ASPSP and 252 were from the AFN. It was recorded the occurrence of food items (fish, cephalopods and crustaceans) and the cephalopods were identified to the lowest taxa possible, according to specialized literature. The Ommastrephidae family represented 84.46% of occurrence in the ASPSP and 63.48% in the AFN, confirming the importance of this family in the area studied and also in the diet of their predators. Among the species with greatest occurrence Ornitoteuthis antillarum was the most representative in both regions. This species had an average mantle length of 54.25 mm, thus demonstrating that the majority of this population is in the juvenile stage of development. The smallest species found was Argonauta nodosa with a mantle length of 4.06 mm and the largest was Ommastrephes bartrami, with 223.33 mm. In the AFN, the species richness (d) was 2.318, the diversity index (H ') was 1.454 and the measure of evenness (J) was 0.585. In the ASPSP, the species richness (d) was 2.66, the Shannon diversity index (H ') was 1.013 and the measure of evenness (J) was 0.373. AFN has a greater cephalopod diversity than ASPSP, confirming the pattern suggested by the Theory of Island Biogeography. Among the occurrence of prey items for all predators, the cephalopods are secondary preys. The most important cephalopod species in the diet of Thunnus albacares and Acantocybium solandri was Ornithoteuthis antillarum. These predators have different niche width the diet of Thunnus albacares is more specialized, but they have an overlap of 84.684% in the trophic niche, suggesting that in the ASPSP these two species may use similar niches

Detecção de predadores por dicromatas e tricromatas humanos e a sua implicação na evolução da visão de cores em primatas

Among placental mammals, primates are the only ones to present trichromatic color vision. However, the distribution of trichromacy among primates is not homogeneous: Old World primates shows an uniform trichromacy (with all individuals being trichromats) and New World primates exhibit a color vision polymorphism (with dichromatic males and dichromatic or trichromatic females). Visual ecology studies have investigated which selective pressures may have been responsible for the evolution of trichromacy in primates, diverging from the dichromat standard found in other mammals. Cues associated with foraging and the socio-reproductive status were analyzed, indicating a trichromatic advantage for the rapid detection of visually conspicuous objects against a green background. However, dichromats are characterized by an efficient capture of cryptic and camouflaged stimuli. These advantages regarding phenotype may be responsible for the maintenance of the visual polymorphism in New World primates and for the high incidence of color blindness in humans (standing around 8% in Caucasian men). An important factor that has not yet been experimentally taken into account is the predation risk and its effect on the evolution of trichromacy in primates. To answer this question, we prepared and edited pictures of animals with different coats: oncillas (Leopardus spp.), puma (Puma concolor) and ferret (Galictis cuja). The specimens were taxidermized and the photographs were taken in three different vegetation scenarios (dense forest, cerrado and grassland). The images of the predators were manipulated so that they fit into two categories of stimulus size (small or large). After color calibration and photo editing, these were presented to 40 humans (20 dichromats and 20 trichromats) by a computer program, which presented a set of four photos at a time (one picture containing the taxidermized animal amid the background vegetation and three depicting only the background vegetation) and recorded the response latency and success rate of the subjects. The results show a trichromatic advantage in detecting potential predators. The predator detection was influenced by the background, the predator species, the dimension of the stimulus and the observer s visual phenotype. As humans have a high rate of dyschromatopsias, when compared to wild Catarrhini or human tribal populations, it is possible that the increased rate of dichromats is a result of reduced pressure for rapid predator detection. Since our species came to live in more cohesive groups and resistant to attack by predators, with the advent of agriculture and the formation of villages, it is possible that the lower risk of predation has reduced the selection in favor of trichromats

Efeito da incorporação de diatomita na estabilidade e permeabilidade de compósitos cimentíceos espumados aplicados a poços de petróleo

Lightweight oilwell cement slurries have been recently studied as a mean to improve zonal isolation and sheath-porous formation adherence. Foamed slurries consisting of Portland cement and air-entraining admixtures have become an interesting option for this application. The loss in hydrostatic pressure as a consequence of cement hydration results in the expansion of the air bubbles entrapped in the cement matrix, thus improving the sheath-porous formation contact. Consequently, slurries are able to better retain their water to complete the hydration process. The main objective of the present study was to evaluate the effect of the addition of an air-entraining admixture on the density, stability and permeability of composite slurries containing Portland cement and diatomite as light mineral load. Successful formulations are potential cementing materials for low fracture gradient oilwells. The experimental procedures used for slurry preparation and characterization were based on the American Petroleum Institute and ABNT guidelines Slurries containing a pre-established concentration of the air-entraining admixture and different contents of diatomite were prepared aiming at final densities of 13 to 15 lb/gal. The results revealed that the reduction of 15 to 25% of the density of the slurries did not significantly affect their strength. The addition of both diatomite and the air-entraining admixture increased the viscosity of the slurry providing better air-bubble retention in the volume of the slurry. Stable slurries depicted bottom to top density variation of less than 1.0 lb/gal and length reduction of the stability sample of 5.86 mm. Finally, permeability coefficient values between 0.617 and 0.406 mD were obtained. Therefore, lightweight oilwell cement slurries depicting a satisfactory set of physicochemical and mechanical properties can be formulated using a combination of diatomite and air-entraining admixtures for low fracture gradient oilwells

Análise paramétrica da simulação composicional do processo de Drenagem Gravitacional Assistida por Gás (GAGD)

In Brazil and around the world, oil companies are looking for, and expected development of new technologies and processes that can increase the oil recovery factor in mature reservoirs, in a simple and inexpensive way. So, the latest research has developed a new process called Gas Assisted Gravity Drainage (GAGD) which was classified as a gas injection IOR. The process, which is undergoing pilot testing in the field, is being extensively studied through physical scale models and core-floods laboratory, due to high oil recoveries in relation to other gas injection IOR. This process consists of injecting gas at the top of a reservoir through horizontal or vertical injector wells and displacing the oil, taking advantage of natural gravity segregation of fluids, to a horizontal producer well placed at the bottom of the reservoir. To study this process it was modeled a homogeneous reservoir and a model of multi-component fluid with characteristics similar to light oil Brazilian fields through a compositional simulator, to optimize the operational parameters. The model of the process was simulated in GEM (CMG, 2009.10). The operational parameters studied were the gas injection rate, the type of gas injection, the location of the injector and production well. We also studied the presence of water drive in the process. The results showed that the maximum vertical spacing between the two wells, caused the maximum recovery of oil in GAGD. Also, it was found that the largest flow injection, it obtained the largest recovery factors. This parameter controls the speed of the front of the gas injected and determined if the gravitational force dominates or not the process in the recovery of oil. Natural gas had better performance than CO2 and that the presence of aquifer in the reservoir was less influential in the process. In economic analysis found that by injecting natural gas is obtained more economically beneficial than CO2

Estudo comparativo da injeção de água usando poços verticais e horizontais

Oil recovery using waterflooding has been until now the worldwide most applied method, specially for light oil recovery, its success is mainly because of the low costs involved and the facilities of the injection process. The Toe- To-Heel Waterflooding TTHWTM method uses a well pattern of vertical injector wells completed at the bottom of the reservoir and horizontal producer wells completed at the top of it. The main producing mechanism is gravitational segregation in short distance. This method has been studied since the early 90´s and it had been applied in Canada with positive results for light heavy oils, nevertheless it hasn´t been used in Brazil yet. In order to verify the applicability of the process in Brazil, a simulation study for light oil was performed using Brazilian northwest reservoirs characteristics. The simulations were fulfilled using the STARS module of the Computer Modelling Group Software, used to perform improved oil recovery studies. The results obtained in this research showed that the TTHWTM well pattern presented a light improvement in terms of recovery factor when compared to the conventional 5- Spot pattern, however, it showed lower results in the economic evaluation

Estudo do processo de drenagem gravitacional do óleo assistido com injeção de vapor e solvente

Como os recursos de hidrocarbonetos convencionais estão se esgotando, a crescente demanda mundial por energia impulsiona a indústria do petróleo para desenvolver mais reservatórios não convencionais. Os recursos mundiais de betume e óleo pesado são estimados em 5,6 trilhões de barris, dos quais 80% estão localizados na Venezuela, Canadá e EUA. Um dos métodos para explorar estes hidrocarbonetos é o processo de drenagem gravitacional assistido com injeção de vapor e solvente (ES-SAGD Expanding Solvent Steam Assisted Gravity Drainage). Neste processo são utilizados dois poços horizontais paralelos e situados verticalmente um acima do outro, um produtor na base do reservatório e um injetor de vapor e solvente no topo do reservatório. Este processo é composto por um método térmico (injeção de vapor) e um método miscível (injeção de solvente) com a finalidade de causar a redução das tensões interfaciais e da viscosidade do óleo ou betume. O objetivo deste estudo é analisar a sensibilidade de alguns parâmetros operacionais, tais como: tipo de solvente injetado, qualidade do vapor, distância vertical entre os poços, porcentagem de solvente injetado e vazão de injeção de vapor sobre o fator de recuperação para 5, 10 e 15 anos. Os estudos foram realizados através de simulações concretizadas no módulo STARS (Steam Thermal, and Advanced Processes Reservoir Simulator) do programa da CMG (Computer Modelling Group), versão 2010.10, onde as interações entre os parâmetros operacionais, estudados em um modelo homogêneo com características de reservatórios semelhantes aos encontrados no Nordeste Brasileiro, foram observadas. Os resultados obtidos neste estudo mostraram que os melhores fatores de recuperação ocorreram para níveis máximos do percentual de solvente injetado e da distância vertical entre os poços. Observou-se também que o processo será rentável dependendo do tipo e do valor do solvente injetado

Dunas costeiras de Jenipabu: Status de conservação e diretrizes para restauração da vegetação

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

Relações ecologicas entre caranguejos e composição arbórea em bosques de mangue naturais e restaurados no nordeste brasileiro

This study aimed to compare the development of crab and tree communities of two restored mangrove areas, one planted with Rhizophora mangle and the other naturally recovered, and also to compare the predation of Grapsid crab Goniopsis cruentata and the Ocypodid Ucides cordatus over the propagules of three mangrove trees: Rhizophora mangle, Avicennia schaueriana e Laguncularia racemosa. Specifically, we tested the hypothesis that Goniopsis predation is more important that Ucides predation, and that these consumers have antagonist effects over propagule consumption. In each area, 10 quadrates were selected at random to analyze tree richness, diameter, height, tree biomass and crab richness and density five years after restoration experiment start. Results show that tree height, biomass and crab density were significantly higher in artificially restored area. No significant differences were observed in crab species richness between areas, but higher tree richness was observed in self-recovered area. Results suggest that planting propagules of Rhizophora can significantly increase tree recovering if the aim was increase tree biomass and crab density, which can accelerate return of ecological functionality. Goniopsis is a more important propagule predator than Ucides both in natural and restored areas. The effects of Goniopis were higher in absence of Ucides, due to negative interactions among these two predator species. The preference of Goniopsis by Avicennia and Laguncularia can favor the dominance of Rhizophora observed in Neotropical mangroves. This study suggests that propagule predation by Goniopsis should be controlled in restoration programs, if dominance of Rhizophora is undesirable respect to more rich tree communities

Mapeamento de ambientes estruturados com extração de informações geométricas através de dados sensoriais

The objective of this thesis is proposes a method for a mobile robot to build a hybrid map of an indoor, semi-structured environment. The topological part of this map deals with spatial relationships among rooms and corridors. It is a topology-based map, where the edges of the graph are rooms or corridors, and each link between two distinct edges represents a door. The metric part of the map consists in a set of parameters. These parameters describe a geometric figure which adapts to the free space of the local environment. This figure is calculated by a set of points which sample the boundaries of the local free space. These points are obtained with range sensors and with knowledge about the robot s pose. A method based on generalized Hough transform is applied to this set of points in order to obtain the geomtric figure. The building of the hybrid map is an incremental procedure. It is accomplished while the robot explores the environment. Each room is associated with a metric local map and, consequently, with an edge of the topo-logical map. During the mapping procedure, the robot may use recent metric information of the environment to improve its global or relative pose

Análise de onda completa de superfície seletiva em freqüência do tipo anteparo duplo

This work presents a theoretical analysis and numerical and experimental results of the scattering characteristics of frequency selective surfaces, using elements of type patch perfectly conductor. The structures are composed of two frequency selective surfaces on isotropic dielectric substrates cascaded, separated by a layer of air. The analysis is performed using the method of equivalent transmission line in combination with the Galerkin method, to determine the transmission and reflection characteristics of the structures analyzed. Specifically, the analysis uses the impedance method, which models the structure by an equivalent circuit, and applies the theory of transmission lines to determine the dyadic Green's function for the cascade structure. This function relates the incident field and surface current densities. These fields are determined algebraically by means of potential incidents and the imposition of the continuity of the fields in the dielectric interfaces. The Galerkin method is applied to the numerical determination of the unknown weight coefficients and hence the unknown densities of surface currents, which are expanded in terms of known basis functions multiplied by these weight coefficients. From the determination of these functions, it becomes possible to obtain numerical scattered fields at the top and bottom of the structures and characteristics of transmission and reflection of these structures. At work, we present numerical and experimental results for the characteristics of transmission and reflection. Comparisons were made with other results presented in literature, and it was observed a good agreement in the cases presented suggestions continuity of the work are presented

Desenvolvimento de um Sistema de Visão Global para uma Frota de Mini-Robôs Móveis

Navigation based on visual feedback for robots, working in a closed environment, can be obtained settling a camera in each robot (local vision system). However, this solution requests a camera and capacity of local processing for each robot. When possible, a global vision system is a cheapest solution for this problem. In this case, one or a little amount of cameras, covering all the workspace, can be shared by the entire team of robots, saving the cost of a great amount of cameras and the associated processing hardware needed in a local vision system. This work presents the implementation and experimental results of a global vision system for mobile mini-robots, using robot soccer as test platform. The proposed vision system consists of a camera, a frame grabber and a computer (PC) for image processing. The PC is responsible for the team motion control, based on the visual feedback, sending commands to the robots through a radio link. In order for the system to be able to unequivocally recognize each robot, each one has a label on its top, consisting of two colored circles. Image processing algorithms were developed for the eficient computation, in real time, of all objects position (robot and ball) and orientation (robot). A great problem found was to label the color, in real time, of each colored point of the image, in time-varying illumination conditions. To overcome this problem, an automatic camera calibration, based on clustering K-means algorithm, was implemented. This method guarantees that similar pixels will be clustered around a unique color class. The obtained experimental results shown that the position and orientation of each robot can be obtained with a precision of few millimeters. The updating of the position and orientation was attained in real time, analyzing 30 frames per second

Desenvolvimento e teste de um protótipo de reator de plasma com gaiola catódica rotatória para nitretação em lote de pequenas peças

The technique of ion nitriding, despite being fully consolidated in the industry, has great limitations when applied to the treatment of small parts. This is because effects that occur due to non-uniformity of the electric field, generate localized heating in parts, damaging the uniformity of nitrided layer. In addition, because the samples are treated static parts thereof are untreated. To expand the use of plasma nitriding, this work presents the development, assembly and testing of a prototype plasma reactor with rotatory cathodic cage [patent pending], able to meet these needs, giving the material a uniform treatment and opening doors to industrial scale production. The samples tested with hexagonal nuts are 6.0 mm in diameter, made of stainless steel AISI 304 nitrided at a pressure of 1 mbar in an atmosphere of 20% H2 + 80% N2 for 1 h. After treatment, testing visual inspection, optical microscopy and microhardness were carried out to check the effectiveness of the process for uniformity and hardness of the parts. All samples exhibited uniform color, and matte brownish, unlike the untreated samples, silver color and gloss. The hardness of the surface (top and sides) was 65% and even higher than the original hardness. The nitrided layer showed great uniformity in microstructure and thickness. It is concluded, therefore, that the unit was effective constructed for the purposes for which it was designed

Utilização de uma coluna de flotação para remoção de compostos orgânicos da água de produção

Innovative technologies using surfactant materials have applicability in several industrial fields, including petroleum and gas areas. This study seeks to investigate the use of a surfactant derived from coconut oil (SCO saponified coconut oil) in the recovery process of organic compounds that are present in oily effluents from petroleum industry. For this end, experiments were accomplished in a column of small dimension objectifying to verify the influence of the surfactant SCO in the efficiency of oil removal. This way, they were prepared emulsions with amount it fastens of oil (50, 100, 200 and 400 ppm), being determined the great concentrations of surfactant for each one of them. Some rehearsals were still accomplished with produced water of the industry of the petroleum to compare the result with the one of the emulsions. According to the experiments, it was verified that an increase of the surfactant concentration does not implicate in a greater oil removal. The separation process use gaseous bubbles formed when a gas stream pass a liquid column, when low surfactant concentrations are used, it occurs the coalescence of the dispersed oil droplets and their transport to the top of the column, forming a new continuous phase. Such surfactants lead to a gas-liquid interface saturation, depending on the used surfactant concentration, affecting the flotation process and influencing in the removal capacity of the oily dispersed phase. A porous plate filter, with pore size varying from 40 to 250 mm, was placed at the base of the column to allow a hydrodynamic stable operation. During the experimental procedures, the operating volume of phase liquid was held constant and the rate of air flow varied in each experiment. The resulting experimental of the study hydrodynamic demonstrated what the capturing of the oil was influenced by diameter of the bubbles and air flow. With the increase flow of 300 about to 900 cm3.min-1, occurred an increase in the removal of oil phase of 44% about to 66% and the removal kinetic of oil was defined as a reaction of 1° order

Estratégia reprodutiva do peixe-voador, Hirundichthys affinis e do peixe agulha preta, Hemiramphus brasiliensis no litoral de Caiçara do Norte, Rio Grande do Norte, Brasil

The flyingfish, Hirundichthys affinis (Günther, 1866) (Exocoetidae) and ballyhoo half beak, Hemiramphus brasiliensis (Linnaeus, 1758) (Hemiramphidae) are marine fish species of commercial value, which contribute to artisanal fishery production of Rio Grande do Norte, Brazil. Besides the economic importance, these fish are important from an ecological point of view, being components in pelagic food chain, where they are the preferred prey of larger predators of high commercial value. This study aimed to determine the reproductive strategies of H. affinis and H. brasiliensis and the fishery production of H. affinis in the northern coast of Rio Grande do Norte. The results are presented in the form of six cientific articles and a review paper. The first article presents the morphometric measurements and meristic counts which confirmed the taxonomic status, population structure in length-weight and the gonad development of H. affinis through macroscopic observations of the ovaries and testes. Females of this species were bigger and heavier than males. The second article describes the reproductive tactics, such as, sex ratio, length at first sexual maturity, histological aspects of gonads, fecundity and spawning season, that indicate the reproductive strategy of H. affinis. The third article shows annual changes in the fishery production of H. affinis in Caiçara do Norte, during the period of 1993 to 2010, emphasizing the relevance of this fish in total fishery production of Rio Grande do Norte, besides registering the fall in production in the years 2008 to 2010. The fourth article describes the population structure, with respect to the length and weight, the length-weight relationship, growth type and sex ratio of Hemiramphus brasiliensis. The fifth article describes the reproductive biology of H. brasiliensis, with details about sex ratio, length at first sexual maturity, fecundity, type of breeding and spawning season. The sixth article deals with the reproductive strategy of H. brasiliensis. The review paper presents the topic of age determination of tropical fish using analysis of otoliths. Both species use the coastal waters of Caiçara do Norte for reproductive purposes. The flying fish, H. affinis migrates from the oceanic waters to the coastal waters to reproduce, coinciding with the rainy season. H. affinis presents total spawning and a seasonal reproductive strategy. However, H. brasiliensis lives and reproduces in the coastal waters displaying partial spawning and an equilibrium reproductive strategy

Utilização de uma coluna de flotação para remoção de compostos orgânicos da água de produção

Innovative technologies using surfactant materials have applicability in several industrial fields, including petroleum and gas areas. This study seeks to investigate the use of a surfactant derived from coconut oil (SCO saponified coconut oil) in the recovery process of organic compounds that are present in oily effluents from petroleum industry. For this end, experiments were accomplished in a column of small dimension objectifying to verify the influence of the surfactant SCO in the efficiency of oil removal. This way, they were prepared emulsions with amount it fastens of oil (50, 100, 200 and 400 ppm), being determined the great concentrations of surfactant for each one of them. Some rehearsals were still accomplished with produced water of the industry of the petroleum to compare the result with the one of the emulsions. According to the experiments, it was verified that an increase of the surfactant concentration does not implicate in a greater oil removal. The separation process use gaseous bubbles formed when a gas stream pass a liquid column, when low surfactant concentrations are used, it occurs the coalescence of the dispersed oil droplets and their transport to the top of the column, forming a new continuous phase. Such surfactants lead to a gas-liquid interface saturation, depending on the used surfactant concentration, affecting the flotation process and influencing in the removal capacity of the oily dispersed phase. A porous plate filter, with pore size varying from 40 to 250 mm, was placed at the base of the column to allow a hydrodynamic stable operation. During the experimental procedures, the operating volume of phase liquid was held constant and the rate of air flow varied in each experiment. The resulting experimental of the study hydrodynamic demonstrated what the capturing of the oil was influenced by diameter of the bubbles and air flow. With the increase flow of 300 about to 900 cm3.min-1, occurred an increase in the removal of oil phase of 44% about to 66% and the removal kinetic of oil was defined as a reaction of 1° order.