Análise não-linear do campo de temperaturas desenvolvidas durante a soldagem do tipo TIG contínuo em placas delgadas

This study offers an analytical approach in order to provide a determination of the temperature field developed during the DC TIG welding of a thin plate of aluminum. The non-linear characteristics of the phenomenon, such as the dependence of the thermophysical and mechanical properties with temperature were considered in this study. In addition to the conductive heat exchange process, were taken into account the exchange by natural convection and radiation. A transient analysis is performed in order to obtain the temperature field as a function of time. It is also discussed a three-dimensional modeling of the heat source. The results obtained from the analytical model were be compared with the experimental ones and those available in the literature. The analytical results show a good correlation with the experimental ones available in the literature, thus proving the feasibility and efficiency of the analytical method for the simulation of the heat cycle for this welding process.

Análise não-linear de treliças pelo método dos elementos finitos posicional

This work presents the positional nonlinear geometric formulation for trusses using different strain measures. The positional formulation presents an alternative approach for nonlinear problems. This formulation considers nodal positions as variables of the nonlinear system instead of displacements (widely found in literature). The work also describes the arc-length method used for tracing equilibrium paths with snap-through and snap-back. Numerical applications for trusses already established in the literature and comparisons with other studies are provided to prove the accuracy of the proposed formulation

Sobre uma cultura do mal-estar com a política

The current dissertation has as its main object of study the malaise with politics phenomenon. To comprehend it, is carried out in this work a inquiry, in different stages of analysis, based in the empirical data raised by the research Os Processos Sociais de Recepção do Horário Gratuito de Propaganda Eleitoral , made by the Grupo de Estudos Mídia e Poder, of the Universidade Federal do Rio Grande do Norte, during the local elections of 2004 in the city of Natal. Based in the focus group technique, such research raised an ample set of information about the decoding process of the electoral television programs, made by six different groups of citizens from the popular classes. Beginning from the presuppose which such process is influenced by the representations about politics made by those subjects, we use that set of empirical information to inquiry not only the decoding, but that same representations which this process is based. In this way, we analyse, in one side, the globally contrary decoding which subjects made from a conforming code of opposition and, in the other, the structure of feeling which it s based, called structure of feeling of the malaise with politics. Such structure is compound by generating themes which expresses the contraposition about the institutionalized politics and, in the same time, a resignation about politics which fortifies the dominant groups hegemony. We support the thesis which this set of representations about politics is caused by the denial of rights frame which those subjects are immersed

A formação do enfermeiro na reflexividade

The study proposes an understanding of nurses training in reflexivity and the overcome the limits of biomedical formation model, from the thought of John Dewey, inserted in the panorama of the reflective practitioner introduced by Donald Schön and dialoguing with the perspective of the transforming action of Paulo Freire. We used a qualitative approach to collect empirical data through focus groups conducted with nursing students from 3rd to 5th year in the Faculty of Health Sciences, Trairi / UFRN in the year 2012. Data analysis occurred through the technique of thematic content analysis constituted of three stages: pre-analysis, exploration of the material, treatment of results, inference and interpretation of the material. Thus, the categories formulated by organizing, classifying and aggregating the the content of the speeches to groups who shared opinions approximations of thought generating a set of categories of analysis designed from the contents. The results present the experiences of nursing students and their reflections, demonstrating that the process of reflection permeates the journey of life. It is inferred that the knowledge acquired in these experiences do not always participate in this dialogue in this formative process, reducing previous experiences in the field of exemplification of everyday situations. We conclude that it is necessary to consolidate innovative pedagogical proposals that allow the continuous dialogue with reality, breaking with the decontextualized teaching process from reality insertion of the university. Rethinking of the structures is recommended, reinforcing the break with the biomedical model and the integration of knowledge dynamically

Desenvolvimento e teste de um modelo estatístico de identificação das proporções de água produzida em zonas de produção de um campo maduro de petróleo

This study investigates the chemical species produced water from the reservoir areas of oil production in the field of Monte Alegre (onshore production) with a proposal of developing a model applied to the identification of the water produced in different zones or groups of zones.Starting from the concentrations of anions and cátions from water produced as input parameters in Linear Discriminate Analysis, it was possible to estimate and compare the model predictions respecting the particularities of their methods in order to ascertain which one would be most appropriate. The methods Resubstitution, Holdout Method and Lachenbruch were used for adjustment and general evaluation of the built models. Of the estimated models for Wells producing water for a single production area, the most suitable method was the "Holdout Method and had a hit rate of 90%. Discriminant functions (CV1, CV2 and CV3) estimated in this model were used to modeling new functions for samples ofartificial mixtures of produced water (producedin our laboratory) and samples of mixtures actualproduced water (water collected inwellsproducingmore thanonezone).The experiment with these mixtures was carried out according to a schedule experimental mixtures simplex type-centroid also was simulated in which the presence of water from steam injectionin these tanks fora part of amostras. Using graphs of two and three dimensions was possible to estimate the proportion of water in the production area

Desenvolvendo e gerenciando compostagem de resíduos sólidos urbanos: para geração de renda e repasse de tecnologia à acrevi

Nowadays, as well as in the past decades, the dumping of biodegradable organic waste in landfill is common practice in Brazil, as well as in most parts of the world. Nevertheless due to its rapid decomposition and release of odors, this practice hamper’s the operation and implementation of a recycling system. These facts encouraged our research to find an efficient system for the management of organic waste, not only for the use of official workers responsible for managing these wastes, but also for non-governmental institutions. The Recycling for Life Community Association – ACREVI (Associação Comunitária Reciclando para a Vida), together with the municipal authorities of Mossoró-RN, Brazil, have assumed the social role of collecting and recycling solid waste produced by most of the local population. However, it was observed that the organic waste it collected was not receiving any treatment. This present work aims to make compost with mixed waste (green waste and organic household), and then do chemical analysis of the material in view to use the waste as organic fertilizer. The objective being: to share the knowledge acquired by putting it into a very simple language accessible to people with little education. The experiment was conducted at ACREVI, Mossoró (RN), and the compost was obtained following the method "windrow", forming three cells (I, II, III) with conical shape, dimensions of 1.6 meters and 2.0 meters in diameter for cells I and II, and 1.0 meters high and 2.0 meters in diameter for cell III. The process was accompanied by analysis: CHN elemental, a variation of cell temperature, humidity, pH, TKN, bulk density, nutrients and heavy metals. Stabilized organic compounds reached the C/N ratio of 10.4/1 cell I and 10.4/1 in the cell II in the cell, showing how good soil conditions, with potential to improve the physical properties of any soil and pH acid soils, has presented the cell III at the end of the process the C/N 26/1, is a high ratio may be associated with the stack size III, thus changing the optimal conditions for the occurrence of the process. The levels of heavy metals in the analyzed compounds were lower than those established by the SDA normative instruction, Nº 27, of 5 June, 2006. The use of pruning trees and grass are used in small-scale composting, while generating a quality compost in the final process, it also created an important condition for a correct sizing of the composting piles. Under the studied conditions it is not advisable to use cells with a height of 1.00 m in height and 2.00 m in diameter, as these do not prevent the rapid dissipation of heat and thus can not be a good product at the end of composting. The composting process in the shed of the association and the preparation of the primer enabled the development of an alternative technology to generate income for members of ACREVI.

Redução in situ de NIO durante a sinterização de misturas NI/NIO produzidas por metalurgia do pó

The nickel alloys are widely used in the production of various materials, especially those that require mechanical strength characteristics associated with resistance to corrosion, for example, the stainless steel. Another use is the production of nickel alloy sintered from powder of metallic nickel. A promising alternative for the production of sintered components of nickel with an important reduction in costs of starting material is the use of mixtures of powders of Ni-NiO. This work aimed to study in situ reduction of NiO during sintering mixtures of Ni / NiO produced by powder metallurgy. The nickel mixtures have been processed by the technique of powder metallurgy and were pre-sintered in an oven under plasma reducing atmosphere of hydrogen. Mixtures Ni +15%NiO, Ni +25%NiO and Ni +35%NiO were studied and compared with samples consisting only of metallic Ni. Dilatometric tests were performed to study the sintering conditions of the mixtures. The consolidated material was analyzed for their microstructure and microhardness. Dilatometry graphs showed that the addition of nickel oxide in all compositions the active sintering the mixtures studied. In tests of microhardness indentations were made at different points of the sample surface. All compositions showed microhardness values close to the consolidated material from metallic nickel. However, sample containing Ni+35% NiO, showed a large dispersion of the values of microhardness tests performed at different points of the sample surface. Microstructural analysis of the material showed a higher concentration of voids and the presence of oxides in the waste composition of the mixtures Ni 35% NiO. The samples containing Ni+15%NiO showed microstructural characteristics and mechanical properties similar to metallic nickel consolidated under the same conditions of the compositions studied in this work and therefore had great potential for production of sintered nickel alloys

Análise numérica do efeito de fatores influentes da reação álcali-agregado no desempenho de estruturas de concreto

The aim of this work is the numerical simulation of the mechanical performance of concrete affected by Alkali-Aggregate Reaction or RAA, reported by Stanton in 1940. The RAA has aroused attention in the context of Civil Engineering from the early 80, when they were reported consequences of his swelling effect in concrete structures, including cracking, failure and loss of serviceability. Despite the availability of experimental results the problem formulation still lacks refinement so that your solution remains doubtful. The numerical simulation is important resource for the assessment of damages in structures caused by the reaction, and their recoveries The tasks of support of this work were performed by means of the finite element approach, about orthotropic non-linear formulation, and, thermodynamic model of deformation by RAA. The results obtained revealed that the swelling effect of RAA induced decline of the mechanical performance of concrete by decreasing the margin of safety prior to the material failure. They showed that the temperature influences, exclusively, the kinetics of the reaction, so that the failure was the more precocious the higher the temperature of the solid mass of concrete

Desenvolvimento de um ressoador retangular de fenda com múltiplas camadas de substrato e com utilização de material PBG para sistema de comunicação sem fio

In the globalized world modern telecommunications have assumed key role within the company, causing a large increase in demand for the wireless technology of communication, which has been happening in recent years have greatly increased the number of applications using this technology. Due to this demand, new materials are developed to enable new control mechanisms and propagation of electromagnetic waves. The research to develop new technologies for wireless communication presents a multidisciplinary study that covers from the new geometries for passive antennas, active up to the development of materials for devices that improve the performance at the frequency range of operation. Recently, planar antennas have attracted interest due to their characteristics and advantages when compared with other types of antennas. In the area of mobile communications the need for antennas of this type has become increasingly used, due to intensive development, which needs to operate in multifrequency antennas and broadband. The microstrip antennas have narrow bandwidth due to the dielectric losses generated by irradiation. Another limitation is the degradation of the radiation pattern due to the generation of surface waves in the substrate. Some techniques have been developed to minimize this limitation of bandwidth, such as the study of type materials PBG - Photonic Band Gap, to form the dielectric material. This work has as main objective the development project of a slot resonator with multiple layers and use the type PBG substrate, which carried out the optimization from the numerical analysis and then designed the device initially proposed for the band electromagnetic spectrum between 3-9 GHz, which basically includes the band S to X. Was used as the dielectric material RT/Duroid 5870 and RT/Duroid 6010.LM where both are laminated ceramic-filled PTFE dielectric constants 2.33 and 10.2, respectively. Through an experimental investigation was conducted an analysis of the simulated versus measured by observing the behavior of the radiation characteristics from the height variation of the dielectric multilayer substrates. We also used the LTT method resonators structures rectangular slot with multiple layers of material photonic PBG in order to obtain the resonance frequency and the entire theory involving the electromagnetic parameters of the structure under consideration. xviii The analysis developed in this work was performed using the method LTT - Transverse Transmission Line, in the field of Fourier transform that uses a component propagating in the y direction (transverse to the real direction of propagation z), thus treating the general equations of the fields electric and magnetic and function. The PBG theory is applied to obtain the relative permittivity of the polarizations for the sep photonic composite substrates material. The results are obtained with the commercial software Ansoft HFSS, used for accurate analysis of the electromagnetic behavior of the planar device under study through the Finite Element Method (FEM). Numerical computational results are presented in graphical form in two and three dimensions, playing in the parameters of return loss, frequency of radiation and radiation diagram, radiation efficiency and surface current for the device under study, and have as substrates, photonic materials and had been simulated in an appropriate computational tool. With respect to the planar device design study are presented in the simulated and measured results that show good agreement with measurements made. These results are mainly in the identification of resonance modes and determining the characteristics of the designed device, such as resonant frequency, return loss and radiation pattern

Materiais supercondutores HTS para arranjos de antenas e aplicação de PBG para micro-ondas

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

Análise de desempenho de um fogão solar com parabola fabricada em material compósito

It is presented a solar cooker made with a parabolic reflector composed by a composite material. For this purpose, it was utilized a cast concrete with a parabolic profile obtained by means of modeling. It will be demonstrated the manufacturing process and settings, as well as tests results, in order to determine the contact temperature and cooking time of some foods. This solar cooker presents the following main characteristics: the concentration method, low cost and easy manufacturing process. It was performed by employing recycled materials such as cement, plaster, crushed polystyrene and wheels. The captation area measures 1 square meter and its parabole was covered with a mirrors measuring 25 cm2. A temperature higher than 650°C was obtained. Furthermore, it has been demonstrated that the cooking viability for several type of foods such as beans, potatoes, rice, yams and pasta can be used in two meals for a family of four. In addition, the advantages of this cooker were analysed in comparison with others described in literature as well as those operating on gas. Especially in Northeast of Brazil, where there is a potential for solar energy, this prototype is an important tool, because it avoids not only desertification, but also pollutants from burning firewoods which cause ecological imbalance

Desenvolvimento e análise de material compósito a base de penas de frango (fibras de queratina-KF) e matriz de poliéster insaturado

Use of natural fibres as a reinforcement material in the manufacture of composites show a series of advantages: availability, biodegradability, low weight and regeneration in relation to synthetic fibres, thus justifying its utilization. In the present research work, composites were developed with chicken feathers (KF), using unsaturated polyester resin as matrix, for diversified applications, mainly in the furniture/timber industry.At present, in Brazil the chicken feathers are used as part of the animal feed, even though this material possesses low aggregated value. The chicken feathers are hollow, light and resistant. After washing with water at room temperature, a part of the chicken feathers were treated with 2% NaOH. Composites were manufactured using treated and untreated chicken feathers with unsaturated orthothalic polyester resin and 1% peroxide as catalyser, obtained in the commerce. Samples with size 150x25x3 mm for mechanical tests were cut by laser in the composite plate. Mechanical analyses were carried out in the Laboratório de Metais e Ensaios Mecânicos UFRN. All the analyses were in accordance with ASTM standards. SEM analyses were also carried out on the samples.In the analyses of the results obtained, it was observed that the composites made with untreated chicken feathers showed better results (Traction 11.406 MPa and 9.107 MPa Bending 34.947 and 20.918 MPa for samples with and without treatment respectively) compared to the composite with treated feathers. Very low values of the water absorption results, evidenced the impermeability characteristic of the feathers. From the SEM images, the structure, fracture and the fibre/matrix adsorption can be evidenced. In the flammability test, it was observed that despite the feathers having sulfur as a constituent, natural inhibitor of flame, no burning support of the composites, because the manufacturing process of the composite

Caracterização e análise das propriedades da fibra de Macambira (Bromelia Laciniosa)

Concern for the environment and the exploitation of natural resources has motivated the development of research in lignocellulosic materials, mainly from plant fibers. The major attraction of these materials include the fact that the fibers are biodegradable, they are a renewable natural resource, low cost and they usually produce less wear on equipment manufacturing when compared with synthetic fibers. Its applications are focused on the areas of technology, including automotive, aerospace, marine, civil, among others, due to the advantageous use in economic and ecological terms. Therefore, this study aims to characterize and analyze the properties of plant fiber macambira (bromelia laciniosa), which were obtained in the municipality of Ielmo Marino, in the state of Rio Grande do Norte, located in the region of the Wasteland Potiguar. The characterization of the fiber is given by SEM analysis, tensile test, TG, FTIR, chemical analysis, in addition to obtaining his title and density. The results showed that the extraction of the fibers, only 0.5% of the material is converted into fibers. The results for title and density were satisfactory when compared with other fibers of the same nature. Its structure is composed of microfibrils and its surface is roughened. The cross section has a non-uniform geometry, therefore, it is understood that its diameter is variable along the entire fiber. Values for tensile strength were lower than those of sisal fibers and curauá. The degradation temperature remained equivalent to the degradation temperatures of other vegetable fibers. In FTIR analysis showed that the heat treatment may be an alternative to making the fiber hydrophobic, since, at high temperature can remove the hemicellulose layer, responsible for moisture absorption. Its chemical constitution is endowed with elements of polar nature, so their moisture is around 8.5% which is equivalent to the percentage of moisture content of hydrophilic fibers. It can be concluded that the fiber macambira stands as an alternative materials from renewable sources and depending on the actual application and purpose, it may achieve satisfactory results

Análise estrutural e avaliação do efeito condroitim sulfato extraído de tilápia (Oreochromis niloticus) em modelo de peritonite aguda

Chondroitin sulfate (CS) is a naturally glycosaminoglycan found in the extracellular matrix of connective tissues and it may be extracted and purified those tissues. CS is involved in various biological functions, which may be related to the having structural variability, despite the simplicity of the linear chain structure from this molecule. Researches in biotechnology and pharmaceutical field with wastes from aquaculture has been developed in Brazil. In recent decades, tilapia (Oreochromis niloticus), native fish from Africa, has been one of the most cultivated species in various regions of the world, including Brazil. The tilapia farming is a cost-effective activity, however, it generates large amount of wastes that are discarded by producers. It is understood that waste from tilapia can be used in research as a source of molecules with important biotechnological applications, which also helps in reducing environmental impacts and promote the development of an ecofriendly activity. Thus, nile tilapia viscera were subjected to proteolysis, then the glycosaminoglycans were complexed with ion exchange resin (Lewatit), it was fractionated with increasing volumes of acetone and purified by ion exchange chromatography DEAE-Sephacel. Further, the fraction was analyzed by agarose gel electrophoresis and nuclear magnetic resonance (NMR). The electrophoretic profile of the compound together the analysis of 1H NMR spectra and the HSQC correlation allow to affirm that the compound corresponds to a molecule like chondroitin sulfate. MTT assay was used to assess cell viability in the presence of CS tilapia isolated and showed that the compound is not cytotoxic to normal cells such as cells from the mouse embryo fibroblast (3T3). Then, this compound was tested for the ability to reduce the influx of leukocytes in model of acute peritonitis (in vivo) induced by sodium thioglycolate. In this context, it was done total and differential leukocytes counting in the blood and peritoneal fluid collected respectively from vena cava and the peritoneal cavity of the animals subjected to the experiment. The chondroitin sulfate for the first time isolated from tilapia (CST ) was able to reduce the migration of leukocytes to the peritoneal cavity of inflamed mice until 80.4 per cent at a dose 10µg/kg. The results also show that there was a significant reduction (p<0.001) of the population of polymorphonuclear leukocytes from peritoneal cavity in the three tested doses (0.1µg/kg; 1µg/kg and 10µg/kg) when it was compared to the positive control (just thioglycolate). Therefore, since the CST structure and mechanism of action has been completely elucidated, this compound may have potential for therapeutic use in inflammatory diseases

Avaliação do banco de dissertações e teses da associação brasileira de antropologia: uma análise cienciométrica

VITULLO, Nadia Aurora Vanti. Avaliação do banco de dissertações e teses da Associação Brasileira de Antropologia: uma análise cienciométrica. 2001. 143 f. Dissertaçao (Mestrado) - Curso de Mestrado em Biblioteconomia e Ciência da Informação, Pontifícia Universidade Católica de Campinas, Campinas, 2001.