Estudo da sinterabilidade de ligas de níquel obtidas por meio dos portadores de liga sic, si3n4 ou si metálico com grafita

Nickel alloys are frequently used in applications that require resistance at high temperatures associated with resistance to corrosion. Alloys of Ni-Si-C can be obtained by means of powder metallurgy in which powder mixtures are made of metallic nickel powders with additions of various alloying carriers for such were used in this study SiC, Si3N4 or Si metal with graphite. Carbonyl Ni powder with mean particle size of 11 mM were mixed with 3 wt% of SiC powders with an average particle size of 15, 30 and 50 μm and further samples were obtained containing 4 to 5% by mass of SiC with average particle size of 15 μm. Samples were also obtained by varying the carrier alloy, these being Si3N4 powder with graphite, with average particle size of 1.5 and 5 μm, respectively. As a metallic Si graphite with average particle size of 12.5 and 5 μm, respectively. The reference material used was nickel carbonyl sintered without adding carriers. Microstructural characterization of the alloys was made by optical microscopy and scanning electron microscopy with semi-quantitative chemical analysis. We determined the densities of the samples and measurement of microhardness. We studied the dissociation of carriers alloy after sintering at 1200 ° C for 60 minutes. Was evaluated also in the same sintering conditions, the influence of the variation of average particle size of the SiC carrier to the proportion of 3% by mass. Finally, we studied the influence of variation of the temperatures of sintering at 950, 1080 and 1200 ° C without landing and also with heights of 30, 60, 120 and 240 minutes for sintering where the temperature was 950 °C. Dilatometry curves showed that the SiC sintered Ni favors more effectively than other carriers alloy analyzed. SiC with average particle size of 15 μm active sintering the alloy more effectively than other SiC used. However, with the chemical and morphological analyzes for all leagues, it was observed that there was dissociation of SiC and Si3N4, as well as diffusion of Si in Ni matrix and carbon cluster and dispersed in the matrix, which also occurred for the alloys with Si carriers and metallic graphite. So the league that was presented better results containing Si Ni with graphite metallic alloy as carriers, since this had dispersed graphite best in the league, reaching the microstructural model proposed, which is necessary for material characteristic of solid lubricant, so how we got the best results when the density and hardness of the alloy

Avaliação da incorporação combinada dos resíduos de cascalho de perfuração de poço de petróleo e de polimento do porcelanato em cerâmica vermelha

Among the industries, those that produce ceramic porcelain for use in construction industry and oil, during the exploration and production period, play an important role in the production of waste. Much research has been carried out both by academia and the productive sector, sometimes reintroducing them in the same production line that generated them, sometimes in areas unrelated to their generation, as in the production of concrete and mortar for the construction, for example, but each one in an isolated way. In this research, the aim is to study the combined incorporation of the waste drill cuttings of oil well and the residue of the polishing of porcelain, generated in the final stage of finishing of this product in a clay matrix, for the production of red pottery, specifically bricks, ceramic blocks and tiles. The clay comes from the municipality of São Gonçalo, RN, the drilling waste is from the Natal basin, in Rio Grande do Norte, and the residue of the polishing proceeds from a ceramic porcelain of the State of Paraíba. For this purpose, we used a mixture of a plastic clay with a non-plastic, in a ratio of 50% each, settling formulations with the addition of these two residues in this clay matrix. In the formulations, both residues were incorporated with a minimum percentage of 2.5% and maximum of 12.5%, varying from 2.5% each, in each formulation, which the sum of the waste be no more than 15%. It should be noted that the residue of the polishing of ceramic porcelain is a IIa class (not inert). The materials were characterized by XRF, XRD, TG, DTA, laser granulometry and the plasticity index. The technological properties of water absorption, apparent porosity, linear shrinkage of burning, flexural tensile strength and bulk density were evaluated after the sintering of the pieces to 850 °C, 950 °C and 1050 °C, with a burning time of 3 hr, 3 hr and 30 minutes, and 3 hr and 50 minutes, respectively, with a heating rate of 10 °C/minute, for all formulations and landing of 30 minutes. To better understand the influence of each residue and temperature on the evaluated properties, we used the factorial planning and its surfaces of response for the interpretation of the results. It was found that the temperature has no statistical significance at a 95% of reliability level in flexural tensile strength and that it decreases the water absorption and the porosity, but increases the shrinkage and the bulk density. The results showed the feasibility of the desired incorporation, but adjusting the temperature to each product and formulation, and that the temperatures of 850 °C and 950 °C were the one that responded to the largest number of formulations

Modelagem e controle de um microveículo aéreo: uma aplicação de estabilidade robusta com a técnica backstepping em uma estrutura hexarrotor

In this Thesis, the development of the dynamic model of multirotor unmanned aerial vehicle with vertical takeoff and landing characteristics, considering input nonlinearities and a full state robust backstepping controller are presented. The dynamic model is expressed using the Newton-Euler laws, aiming to obtain a better mathematical representation of the mechanical system for system analysis and control design, not only when it is hovering, but also when it is taking-off, or landing, or flying to perform a task. The input nonlinearities are the deadzone and saturation, where the gravitational effect and the inherent physical constrains of the rotors are related and addressed. The experimental multirotor aerial vehicle is equipped with an inertial measurement unit and a sonar sensor, which appropriately provides measurements of attitude and altitude. A real-time attitude estimation scheme based on the extended Kalman filter using quaternions was developed. Then, for robustness analysis, sensors were modeled as the ideal value with addition of an unknown bias and unknown white noise. The bounded robust attitude/altitude controller were derived based on globally uniformly practically asymptotically stable for real systems, that remains globally uniformly asymptotically stable if and only if their solutions are globally uniformly bounded, dealing with convergence and stability into a ball of the state space with non-null radius, under some assumptions. The Lyapunov analysis technique was used to prove the stability of the closed-loop system, compute bounds on control gains and guaranteeing desired bounds on attitude dynamics tracking errors in the presence of measurement disturbances. The controller laws were tested in numerical simulations and in an experimental hexarotor, developed at the UFRN Robotics Laboratory

Territorialidade e pesca: atualidades e tradições no uso dos recursos pesqueiros na comunidade litorânea da praia da Pipa Rio Grande do Norte

The need for sustainability in the exploitation of natural resources in coastal areas has been out in recent years, as well as the social and cultural sustainability of traditional communities in these regions. Coastal and estuarine wild areas are influenced directly or indirectly by a set of human activities such as artisanal fishing. Therefore, there is a demand for an integrated design of these areas and according to the landing values, a pattern of unsustainable development of national marine fishing activity. The study was conducted in the coastal community of Praia da Pipa, Tibau do Sul municipality, RN, between june 2009 and june 2010 and aimed to characterize the fishery performed, its socio-economic strategies and fishing areas, as well as to identify ichthyofauna, to assess the sustainability of the major resources and to identify cultural traits related to artisanal fisheries, their problems and prospects; linking tradition and the present fishing activity carried out in the community. For this study, a total of 67 structured interviews were collected, including qualitative and quantitative data. A total of 133 fish landings and direct observations were performed. Informants were identified according to one of the following categories: fishermen, vessel masters and members of the local population with offspring. Applications SPSS 10.0, Paint.Ink and Microsoft Office Excel 2007 were used for tabulation and analysis of results. Local fishermen are, on average, 25 years fishing, have 40 years old and the average monthly income is up to 03 minimum wages. The local fleet consists of 20 vessels, that uses different line sizes and types of networks, operating in 21 fishing grounds and showing a reduction in the vessel numbers by 66% in the last decade. We recorded 76 species of fish, captured by the local fleet and the top 5 were quantitatively analyzed serra spanish mackarel (Scomberomorus brasiliensis), little tunny (Euthynnus alleteratus), yellowtail snapper (Ocyurus chrysurus), red snapper (Lutjanus analis) and common snook (Centropomus undecimalis), accounting for 46,5% of production in the period. The capture of these species was composed mostly of adults. Data analysis showed a significant decrease of the local fishing activity over the last decade due to the weakness displayed by the political-social category, the devaluation of local knowledge and the emergence of new sources of income through increased tourism. The characteristics of the fishing community suggest it to pass through significant changes as the appreciation of their cultural and traditional aspects. We identified a tendency to sustainability of main species caught, suggesting that public policies to be adopted locally comply with the current characteristics of fishing undertaken in the community and knowledge of fishermen related to the environment, allowing environmental, as well as social and cultural sustainability of the community involved.

Reprodução do capital e metamorfoses espaciais : um estudo da verticalização de Ponta Negra, Natal/RN

The broach presented in this dissertation, linked to post graduate Geography´s of the Universidade Federal do Rio Grande do Norte - UFRN, more exactly about the research group entitled interdisciplinary studies unit on space and housing built . The research developed through this study has this central theme on vertical grounding of the construction in the neighborhood of ponta negra in Natal, Rio Grande do Norte. Realizing this momentum as a way of accumulation of capital in city. Rio Grande do Norte´s city. During the 2000 s , the neighborhood of Ponta Negra went through an intense process of vertical integration of its ground, Provided by many factor of conditions created from new economic, political and social functions which start to be outlined mainly from the tourism development in this neighborhood since the 80´s decade. The Tourism development and the landing planning of the ponta negra´s neighborhood promoted for the government by using order to police the city´s urbanization, beyond the sense of the civilian building actors. They enabled this neighborhood to become propitious to the real estate investments. Many ventures were built before the year of 2010 while another are on building, which, over the years, changed the sociospatyal dinamics of the neighborhood. Considering the urban space is socially built, product and condition for the reproductive process of the capitalist society, the goal of this research is to investigate the verticalization of the ground, for capital reproduction purposes. This research aims to analyze the vertical this quarter through the theory of social production of space by Henri Lefebvre. The Methodology adopted pervades for secondary and primary research, compound for bibliographic research, documentary, journal, magazines, camp research and interview, to reach the best way to analyse the dynamics of the refered neighborhood

Uma abordagem ergonômica para análise da qualidade do pescado, desde sua captura ao seu desembarque na praia, resultante da atividade dos jangadeiros de Ponta Negra - Natal/RN

The artisan fishing activity, which involves historical - cultural, environmental, social, political, economi c, among other factors, presents, nowadays, as an important source of income, creating jobs and food, contributing to the permanence of man in their own birthplace. However, the fish, considered one of the most perishable foods, requires a proper handling and conservation, from capture to its availability in the market, in order to slow the deterioration process. Thereby, this dissertation aims to study the effect of the manipulation practices on fish quality, from capture to its landing on the beach, resul ting from fisherman’s activity from Ponta Negra - Natal/RN. It also presents the purpose of analyzing the quality of the fish and propose recommendations for their proper handling and possible solutions to add value to the product, through the improvement of the quality and good handling practices. For this purpose, the methodology used was based on ergonomic analysis of their work through observational techniques and interactional with the focus group, the jangadeiros, to understand their activity and eval uated the freshness and quality of the fish by sensory analysis, and microbiological parameters and physicochemical from existing legislation Ordinance No. 185 of May 13, 1997 and RIISPOA - amended on December 1, 2007 and RDC No. 12, dated January 2, 2001. According to the results obtained in laboratory tests, it can be established, the acceptable quality of fish as the existing rules and regulations parameters , not getting significant deterioration caused by poor handling and improper storage of fish.

Estudo da sinterabilidade de ligas de níquel obtidas por meio dos portadores de liga sic, si3n4 ou si metálico com grafita

Nickel alloys are frequently used in applications that require resistance at high temperatures associated with resistance to corrosion. Alloys of Ni-Si-C can be obtained by means of powder metallurgy in which powder mixtures are made of metallic nickel powders with additions of various alloying carriers for such were used in this study SiC, Si3N4 or Si metal with graphite. Carbonyl Ni powder with mean particle size of 11 mM were mixed with 3 wt% of SiC powders with an average particle size of 15, 30 and 50 μm and further samples were obtained containing 4 to 5% by mass of SiC with average particle size of 15 μm. Samples were also obtained by varying the carrier alloy, these being Si3N4 powder with graphite, with average particle size of 1.5 and 5 μm, respectively. As a metallic Si graphite with average particle size of 12.5 and 5 μm, respectively. The reference material used was nickel carbonyl sintered without adding carriers. Microstructural characterization of the alloys was made by optical microscopy and scanning electron microscopy with semi-quantitative chemical analysis. We determined the densities of the samples and measurement of microhardness. We studied the dissociation of carriers alloy after sintering at 1200 ° C for 60 minutes. Was evaluated also in the same sintering conditions, the influence of the variation of average particle size of the SiC carrier to the proportion of 3% by mass. Finally, we studied the influence of variation of the temperatures of sintering at 950, 1080 and 1200 ° C without landing and also with heights of 30, 60, 120 and 240 minutes for sintering where the temperature was 950 °C. Dilatometry curves showed that the SiC sintered Ni favors more effectively than other carriers alloy analyzed. SiC with average particle size of 15 μm active sintering the alloy more effectively than other SiC used. However, with the chemical and morphological analyzes for all leagues, it was observed that there was dissociation of SiC and Si3N4, as well as diffusion of Si in Ni matrix and carbon cluster and dispersed in the matrix, which also occurred for the alloys with Si carriers and metallic graphite. So the league that was presented better results containing Si Ni with graphite metallic alloy as carriers, since this had dispersed graphite best in the league, reaching the microstructural model proposed, which is necessary for material characteristic of solid lubricant, so how we got the best results when the density and hardness of the alloy

Avaliação da incorporação combinada dos resíduos de cascalho de perfuração de poço de petróleo e de polimento do porcelanato em cerâmica vermelha

Among the industries, those that produce ceramic porcelain for use in construction industry and oil, during the exploration and production period, play an important role in the production of waste. Much research has been carried out both by academia and the productive sector, sometimes reintroducing them in the same production line that generated them, sometimes in areas unrelated to their generation, as in the production of concrete and mortar for the construction, for example, but each one in an isolated way. In this research, the aim is to study the combined incorporation of the waste drill cuttings of oil well and the residue of the polishing of porcelain, generated in the final stage of finishing of this product in a clay matrix, for the production of red pottery, specifically bricks, ceramic blocks and tiles. The clay comes from the municipality of São Gonçalo, RN, the drilling waste is from the Natal basin, in Rio Grande do Norte, and the residue of the polishing proceeds from a ceramic porcelain of the State of Paraíba. For this purpose, we used a mixture of a plastic clay with a non-plastic, in a ratio of 50% each, settling formulations with the addition of these two residues in this clay matrix. In the formulations, both residues were incorporated with a minimum percentage of 2.5% and maximum of 12.5%, varying from 2.5% each, in each formulation, which the sum of the waste be no more than 15%. It should be noted that the residue of the polishing of ceramic porcelain is a IIa class (not inert). The materials were characterized by XRF, XRD, TG, DTA, laser granulometry and the plasticity index. The technological properties of water absorption, apparent porosity, linear shrinkage of burning, flexural tensile strength and bulk density were evaluated after the sintering of the pieces to 850 °C, 950 °C and 1050 °C, with a burning time of 3 hr, 3 hr and 30 minutes, and 3 hr and 50 minutes, respectively, with a heating rate of 10 °C/minute, for all formulations and landing of 30 minutes. To better understand the influence of each residue and temperature on the evaluated properties, we used the factorial planning and its surfaces of response for the interpretation of the results. It was found that the temperature has no statistical significance at a 95% of reliability level in flexural tensile strength and that it decreases the water absorption and the porosity, but increases the shrinkage and the bulk density. The results showed the feasibility of the desired incorporation, but adjusting the temperature to each product and formulation, and that the temperatures of 850 °C and 950 °C were the one that responded to the largest number of formulations