Nitretação em plasma com gaiola catódica: caracterização e avaliação do desempenho da camada nitretada em facas de corte

Nowadays, in the plastic industry are used mills that accomplish the recycling of residues generated in the production of its components. These mills contain cut sheets that suffer accelerated wear, once they are submitted constantly to the tribologic efforts, decreasing its useful life. To reduce this problem, it s used noble steels or takes place superficial treatments. The ionic nitriding process presents some limitations related to the uniformity of the layer in pieces with complex geometry, committing its application in pieces as knives, head offices, engagements, etc. However, the new technique of nitriding in cathodic cage eliminates some problems, as the restrictions rings, inherent to the conventional ionic nitriding. In present work, was studied the use viabilization of steels less noble, as SAE 1020, SAE 4320 and SAE 4340, nitreded by two different techniques, to substitute the AISI 01 steels, usually used in the cut knifes fabrication, seeking to reduce the costs and at the sane time to increase the useful life of these knifes. The steel most viable was the SAE 4340, nitrided in cathodic cage, because it presented uniformity in thickness and in the hardness of the layer, besides of increased 58% in the average its useful life

Nitretação em plasma com gaiola catódica: caracterização e avaliação do desempenho da camada nitretada em facas de corte

Nowadays, in the plastic industry are used mills that accomplish the recycling of residues generated in the production of its components. These mills contain cut sheets that suffer accelerated wear, once they are submitted constantly to the tribologic efforts, decreasing its useful life. To reduce this problem, it s used noble steels or takes place superficial treatments. The ionic nitriding process presents some limitations related to the uniformity of the layer in pieces with complex geometry, committing its application in pieces as knives, head offices, engagements, etc. However, the new technique of nitriding in cathodic cage eliminates some problems, as the restrictions rings, inherent to the conventional ionic nitriding. In present work, was studied the use viabilization of steels less noble, as SAE 1020, SAE 4320 and SAE 4340, nitreded by two different techniques, to substitute the AISI 01 steels, usually used in the cut knifes fabrication, seeking to reduce the costs and at the sane time to increase the useful life of these knifes. The steel most viable was the SAE 4340, nitrided in cathodic cage, because it presented uniformity in thickness and in the hardness of the layer, besides of increased 58% in the average its useful life

Construção, caracterização e aplicação de eletrodos para descarga por arco de cátodo oco

The system built to characterize electrodes and, consequently, deposited fine films are constituted by a hollow cathode that works to discharges and low pressures (approximately 10-3 to 5 mbar), a source DC (0 to 1200 V), a cylindrical camera of closed borossilicato for flanges of stainless steel with an association of vacuum bombs mechanical and spread. In the upper flange it is connected the system of hollow cathode, which possesses an entrance of gas and two entrances for its refrigeration, the same is electrically isolated of the rest of the equipment and it is polarized negatively. In front of the system of hollow cathode there is a movable sample in stainless steel with possibility of moving in the horizontal and vertical. In the vertical, the sample can vary its distance between 0 and 70 mm and, in the horizontal, can leave completely from the front of the hollow cathode. The sample and also the cathode hollow are equipped with cromel-alumel termopares with simultaneous reading of the temperatures during the time of treatment. In this work copper electrodes, bronze, titanium, iron, stainless steel, powder of titanium, powder of titanium and silício, glass and ceramic were used. The electrodes were investigated relating their geometry change and behavior of the plasma of the cavity of hollow cathode and channel of the gas. As the cavity of hollow cathode, the analyzed aspects were the diameter and depth. With the channel of the gas, we verified the diameter. In the two situations, we investigated parameters as flow of the gas, pressure, current and applied tension in the electrode, temperature, loss of mass of the electrode with relationship at the time of use. The flow of gas investigated in the electrodes it was fastened in a work strip from 15 to 6 sccm, the constant pressure of work was among 2.7 to 8 x 10-2 mbar. The applied current was among a strip of work from 0,8 to 0,4 A, and their respective tensions were in a strip from 400 to 220 V. Fixing the value of the current, it was possible to lift the curve of the behavior of the tension with the time of use. That curves esteem in that time of use of the electrode to its efficiency is maximum. The temperatures of the electrodes were in the dependence of that curves showing a maximum temperature when the tension was maximum, yet the measured temperatures in the samples showed to be sensitive the variation of the temperature in the electrodes. An accompaniment of the loss of mass of the electrode relating to its time of use showed that the electrodes that appeared the spherical cavities lost more mass in comparison with the electrodes in that didn't appear. That phenomenon is only seen for pressures of 10-2 mbar, in these conditions a plasma column is formed inside of the channel of the gas and in certain points it is concentrated in form of spheres. Those spherical cavities develop inside of the channel of the gas spreading during the whole extension of the channel of the gas. The used electrodes were cut after they could not be more used, however among those electrodes, films that were deposited in alternate times and the electrodes that were used to deposit films in same times, those films were deposited in the glass substrata, alumina, stainless steel 420, stainless steel 316, silício and steel M2. As the eletros used to deposit films in alternate time as the ones that they were used to deposit in same times, the behavior of the thickness of the film obeyed the curve of the tension with relationship the time of use of the electrode, that is, when the tension was maximum, the thickness of the film was also maximum and when the tension was minimum, the thickness was minimum and in the case where the value of the tension was constant, the thickness of the film tends to be constant. The fine films that were produced they had applications with nano stick, bio-compatibility, cellular growth, inhibition of bacterias, cut tool, metallic leagues, brasagem, pineapple fiber and ornamental. In those films it was investigated the thickness, the adherence and the uniformity characterized by sweeping electronic microscopy. Another technique developed to assist the production and characterization of the films produced in that work was the caloteste. It uses a sphere and abrasive to mark the sample with a cap impression, with that cap form it is possible to calculate the thickness of the film. Through the time of life of the cathode, it was possible to evaluate the rate of waste of its material for the different work conditions. Values of waste rate up to 3,2 x 10-6 g/s were verified. For a distance of the substratum of 11 mm, the deposited film was limited to a circular area of 22 mm diameter mm for high pressures and a circular area of 75 mm for pressure strip. The obtained films presented thickness around 2,1 µm, showing that the discharge of arch of hollow cathode in argon obeys a curve characteristic of the tension with the time of life of the eletrodo. The deposition rate obtained in this system it is of approximately 0,18 µm/min

Plásticos reforçados a base de tecidos híbridos: efeitos da anisotropia e geometria normativa na caracterização mecânica e da fratura

As most current studies, reinforced plastics have been, in recent years, a viable alternative in building structural elements of medium and large, since the lightness accompanied by high performance possible. The design of hybrid polymer composites (combination of different types of reinforcements) may enable structural applications thereof, facing the most severe service conditions. Within this class of composite materials, reinforced the underlying tissues hybrid high performance are taking space when your application requires high load bearing and high rigidity. The objective of this research work is to study the challenges in designing these fabrics bring these materials as to its mechanical characterization and fracture mechanisms involved. Some parameters associated with the process and / or form of hybridization stand out as influential factors in the final performance of the material such as the presence of anisotropy, so the fabric weave, the process of making the same, normative geometry of the specimens, among others. This sense, four laminates were developed based hybrid reinforcement fabrics involving AS4 carbon fiber, kevlar and glass 49-E as the matrix epoxy vinyl ester resin (DERAKANE 411-350). All laminates were formed each with four layers of reinforcements. Depending on the hybrid fabric, all the influencing factors mentioned above have been studied for laminates. All laminates were manufactured industrially used being the lamination process manual (hand-lay-up). All mechanical characterization and study of the mechanism of fracture (fracture mechanics) was developed for laminates subjected to uniaxial tensile test, bending in three and uniaxial compression. The analysis of fracture mechanisms were held involving the macroscopic, optical microscopy and scanning electron microscopy

Frequência da infecção por Toxoplasma gondii em galinhas caipira e frangos de corte em regiões dos Estados do Rio Grande do Norte e Paraíba

Toxoplasmosis is a zoonosis caused by Toxoplasma gondii, a protozoan that has a cosmopolitan geographic distribution and low host specificity. Usually a benign and selflimiting, infection can manifest itself in a severe systemic becoming overwhelming in fetuses and patients with immunosuppression. Domestic fowl are considered one of the most important hosts in the epidemiology of toxoplasmosis, since they are potential sources of infection for humans, in addition to playing the role of important indicators of environmental contamination by oocysts of T. gondii. We studied the prevalence of infection by the protozoan in chickens of different breeding systems mesoregions from the states of Rio Grande do Norte and Paraiba: broilers from commercial farms (200/PB) and free-range chickens of small farms (322/RN and PB). Were standardized IFAT and ELISA techniques for detecting specific antibodies in blood samples of birds, and commercial kit was used to determine the prevalence by IHAT. There was no seropositive reaction by T. gondii in the samples of broilers tested, indicating that the particularities of intensive management limit the chances of infection for these animals. Among the hens, the frequency of IgG anti-T. gondii diagnosed by the techniques of IHAT, IFAT and ELISA, respectively, were 3.73% (12/322), 37.88% (122/322) and 40.37% (130/322), for both young and adult animals. Amongst the seropositive samples by IFAT, 33 (27.05%) were positive at a dilution of 1:16, in 1:32, 31 (25.41%), in 1:64, 24 (19.67%), 15 (12.29%) in 1:128, and 19 presented titer greater than or equal to 1:256 (15.57%). The evaluation of the presence of anti-T. gondii should be careful, and reagents IHAT provided erratic results in this measure for the specie studied. This suggests the need for own standardization of the kit before the use in epidemiological studies in animal species. On the other hand, substantial agreement observed between IFAT and ELISA techniques (Kappa = 0.62) enables these methods as effective methodologies for the diagnosis of toxoplasmosis in chickens. The high prevalence of specific antibodies among poultry in the region studied attempts to the potential risk of transmission of toxoplasmosis to humans

A missão política do Supremo Tribunal Federal: análise de sua importância como corte constitucional para o controle do poder no Brasil

The following study proposes an analysis of the politic process which the brazilian constitutional justice faces, emphasizing the Supremo Tribunal Federal . For that purpose, we start by examining the intimate relationship between Politics and Law, in view of the most recent social systems theories, so that the political system is distinguished by the exclusiveness of using the physical force, intending to make coletive tying decisions, and the juridical system as a congruent generalization of the expectations towards the rules and principles, brought together under an interdependence by which both gather legitimacy and effectiveness. In this manner we can notice the political effects of the constitutional interpretation conducted by Judges as well as by other juridical professionals, because these ones decrease the overload of expectations which are pointed to the Judicature. Constitutional interpretation is democratized since the participative democracy arises and stablishes a permanent state of awareness around the exercise of power and favours the preservation of the pluralism (counter-majoritary principle) where we can find the origin of the democratic nature of constitutional courts, once, in most cases, their members are not elected by the people. After that, we analyse the historical posture of the Supremo Tribunal Federal as a constitutional court in Brazil, so we can realize the attempts to make it vulnerable to the appeals of governability and economical aims, agains which this court somehow has resisted, stressing its particularities. At the end, it s concluded that even the so-called acts of government, whose judiciary control is mostly repelled, are subjected to a constitutional analysis, last frontier to be explored by the Supremo Tribunal Federal in its role of exposing our republican Constitution

Geometria e simetria nas rendas de bilro: contribuições para matemática escolar

A tese tem como objetivo descrever e analisar características e princípios dos padrões das rendas de bilro de modo a estabelecer relações com a Matemática escolar, principalmente, no que se refere aos tópicos como Geometria, simetria, isometria, área, perímetro, entre outros. Desse modo, elaboramos atividades didáticas, com base na Matemática explorada nos padrões da criação da renda de bilro, visando concretizar um exercício investigatório nas aulas de Matemática, de modo que, sejam estabelecidas relações conceituais entre a prática investigada e os conteúdos da Matemática escolar. Para satisfazer esses objetivos, buscamos apoio metodológico na pesquisa bibliográfica, do tipo documental em catálogos como o da Professora Valdelice Girão (1984) e também o de Dawson (1984). Realizamos também a pesquisa empírica durante as visitas ao Museu do Ceará e ao Centro das Rendeiras na Prainha, em Aquiraz, no Ceará. Para realizar as atividades didáticas, apoiamo-nos em Mendes (2009). Consideramos relevante essa abordagem de ensino porque pressupõe a experiência direta do aprendiz com situações reais vivenciadas, nas quais a abordagem instrucional é centrada no aluno. Desse modo, concluímos que para o ensino de conteúdos como Geometria, simetria, isometria, relação entre perímetro e área, entre outros que são abordados na Educação Básica, os modelos decorrentes da criação renda de bilro e outros modelos já descritos na tradição cearense podem ser usados como artefato cultural na criação de atividades didáticas

Estudo do comportamento no estado fresco e endurecido do concreto com incorporação de resíduo de corte de botão

This works aims at investigating the effects of adding waste from RCBP-polyester button manufacturing to Portland cement concrete, particularly regarding its consistency and mechanic strength. The RCBP used came from a button factory located in Parnamirim, RN, Brazil. The waste was added to the concrete on different ratios: 5 %, 10 %, 15 % and 20 % of the total cement mass. A sample of concrete without the RCBP was used as reference, 1:1,33:2,45:0,50. For the mechanic strength test four samples were tested with different ages (3, 7 and 28 days old) and mixtures. Furthermore, a Slump Test was also conducted in order to verify the concrete s consistency. A tendency to a reduction in the compression resistance was noticed for all samples. For the samples with 5 % and 10 %, there was also an increase in the traction resistance during inflexion, regarding the reference concrete. In the microstructural analysis, the RBCP was observed to show an irregular and porous surface, thus explaining the consistency decrease

Uma proposta de FSS fractal com geometria simplificada

Frequency Selective Surfaces (FSS) are periodic structures in one or two dimensions that act as spatial filters, can be formed by elements of type conductors patches or apertures, functioning as filters band-stop or band-pass respectively. The interest in the study of FSS has grown through the years, because such structures meet specific requirements as low-cost, reduced dimensions and weighs, beyond the possibility to integrate with other microwave circuits. The most varied applications for such structures have been investigated, as for example, radomes, antennas systems for airplanes, electromagnetic filters for reflective antennas, absorbers structures, etc. Several methods have been used for the analysis of FSS, among them, the Wave Method (WCIP). Are various shapes of elements that can be used in FSS, as for example, fractal type, which presents a relative geometric complexity. This work has as main objective to propose a simplification geometric procedure a fractal FSS, from the analysis of influence of details (gaps) of geometry of the same in behavior of the resonance frequency. Complementarily is shown a simple method to adjust the frequency resonance through analysis of a FSS, which uses a square basic cell, in which are inserted two reentrance and dimensions these reentrance are varied, making it possible to adjust the frequency. For this, the structures are analyzed numerically, using WCIP, and later are characterized experimentally comparing the results obtained. For the two cases is evaluated, the influence of electric and magnetic fields, the latter through the electric current density vector. Is realized a bibliographic study about the theme and are presented suggestions for the continuation of this work

Tecnologia mais limpa para produção de mel seco de cana e sua inclusão em rações de frangos de corte

This study analyzed the effects of adding dry sugar cane molasses (MSC) to the feed of broiler chickens, and determining the economic feasibility of use of this type of diet; 240 male Ross race broiler chickens, one day in age, were utilized in this study. The experimental desing was a completely randomized whit 6 treatments and 4 replications, in 24 portions of 10 birds per parcel. The treatments corresponded to 6 rations (T1-T6) in phase initial (1-21 days) and 6 rations (T1-T6) in phasem finish (22-42 days) characterized by substitution of corn meal in levels increase 0, 5, 10, 15, 20 e 25% by the molasse dried sugar-cane. The birds received water and free ration during the whole creation phase, being the iso-proteins and iso-calories rations. The variance analysis showed the 1 a 21 days significant differences for average gain weight (P<0,05), average consumption of ration (P<0,05) and average alimentary conversion (P<0,05) and the 22 a 42 days, the analysis of variance showed significant differences for gain in weight (P<0,01) and average alimentary conversion (P<0,05). There no difference significant on average consumption of ration (P>0,05) the 22 a 42 days of age. Results showed out that is possible to use molasse dried sugar-cane up to 8,3 % in broilers ration. It was concluded the level of 8,3 % of addition gave the best economical returns in the experimental conditions

A modelagem matemática como alternativa de ensino e aprendizagem da geometria na educação de jovens e adultos

This is work itself insert in the mathematics education field of the youth and adult education to aim to practitioners of the educational action into the mathematics area performing to with this is teaching kind, adopting to as parameter the Mathematics Molding approach. The motive of the research is to draw up a application proposal of the molding mathematics as teaching and learning geometry alternative in the youth and adult education. The research it develops in three class of the third level (series 5th and 6th) of he youth and adults education in the one school municipal from the Natal outskirts. Its have qualitative nature with participating observation approach, once performing to directly in to research environment as a mathematics teacher of those same classes. We are used questionnaires, lesson notes and analyses of the officials documents as an basis of claim instruments. The results indicates that activity used the mathematic moldings were appreciated the savoir-faire of the student in to knowledge construction process, when search develop to significant learning methods, helping to student build has mathematics connections with other knowledge areas and inside mathematics himself, so much that enlarges your understanding and assist has in your participation in the other socials place, over there propitiate to change in student and teacher posture with relation to mathematic classroom dynamics

Geometria e arirmética numa visão multicultural: uma experiência pedagógica

This paper aims to build a notebook of activities that can help the teacher of elementary school mathematics. Topics covered are arithmetic and geometry and the activities proposed here were developed aiming print them a multicultural character. We take as a base line developed by Claudia Zaslavsky multiculturalism and reflected in his books "Games and activities worldwide" and "More games and activities worldwide." We structure our work around four themes: the symbol of the Olympic Games, the pyramids of Egypt, the Russian abacus abacus and Chinese. The first two themes allow you to explore basic concepts of geometry while the latter two themes allow us to explore numerical notation and arithmetic operations

Geometrias não-eucludianas como anomalias: implicações para o ensino de geometria e medidas

This present research the aim to show to the reader the Geometry non-Euclidean while anomaly indicating the pedagogical implications and then propose a sequence of activities, divided into three blocks which show the relationship of Euclidean geometry with non-Euclidean, taking the Euclidean with respect to analysis of the anomaly in non-Euclidean. PPGECNM is tied to the line of research of History, Philosophy and Sociology of Science in the Teaching of Natural Sciences and Mathematics. Treat so on Euclid of Alexandria, his most famous work The Elements and moreover, emphasize the Fifth Postulate of Euclid, particularly the difficulties (which lasted several centuries) that mathematicians have to understand him. Until the eighteenth century, three mathematicians: Lobachevsky (1793 - 1856), Bolyai (1775 - 1856) and Gauss (1777-1855) was convinced that this axiom was correct and that there was another geometry (anomalous) as consistent as the Euclid, but that did not adapt into their parameters. It is attributed to the emergence of these three non-Euclidean geometry. For the course methodology we started with some bibliographical definitions about anomalies, after we ve featured so that our definition are better understood by the readers and then only deal geometries non-Euclidean (Hyperbolic Geometry, Spherical Geometry and Taxicab Geometry) confronting them with the Euclidean to analyze the anomalies existing in non-Euclidean geometries and observe its importance to the teaching. After this characterization follows the empirical part of the proposal which consisted the application of three blocks of activities in search of pedagogical implications of anomaly. The first on parallel lines, the second on study of triangles and the third on the shortest distance between two points. These blocks offer a work with basic elements of geometry from a historical and investigative study of geometries non-Euclidean while anomaly so the concept is understood along with it s properties without necessarily be linked to the image of the geometric elements and thus expanding or adapting to other references. For example, the block applied on the second day of activities that provides extend the result of the sum of the internal angles of any triangle, to realize that is not always 180° (only when Euclid is a reference that this conclusion can be drawn)

Avaliação de pastagens tropicais em sistemas de produção de ovinos de corte no nordeste brasileiro

He aim of this study was to evaluate the structural characters, herbage accumulation, nutritive value and performance of sheep in different tropical pastures. The treatments were two cultivars and two of the genera Panicum Brachiaria pastures under intermittent stocking and variable stocking rate, in the rainy season. We evaluated the masses and the components of herbage pre grazing in two layers, and after grazing. Chemical analyzes were made of the stems and leaf blades pre grazing in two layers. We used 48 male sheep and whole for the assessment of individual weight gain and area, and anestrous females to adjust the stocking rate. In the cv. Massai showed the highest herbage mass, leaf blades and dead material, and the largest volume density and leaf blade: stem pre grazing. There was no difference among cultivars for the percentage of leaf blade (PLB) in both strata, but the higher the PLB was higher than the bottom. The highest percentage of dead material (PDM) was observed in cvs. Massai and Marandu in the two strata. In cvs. Massai and Piatã were observed lower levels of crude protein in stem and leaf. In stratum 0-25 cm lower nutritional value was observed in the stem in the leaf blades did not grant the nutritional value among the strata. Herbage mass, leaf blade, PLB and proportion of stem in the residue of the Massai pastures were higher than cv. Aruana. There was no difference for efficiencies in harvest leaf and stem between the cultivars. The cv. Massai got the higher accumulation of leaf per cycle per day. Animals kept in grass swards Aruana had the highest average daily gain. The higher stocking rates and earnings per area were observed in grass swards and Marandu Massai. The cultivars are suitable for sheep meat production in the rainy season

Suplementacao de zinco orgânico na racão de frangos de corte alojados em cama nova ou reutilizada

Abstract: Several factors can affect the development of the broiler, among them we can highlight nutrition and management. In the context nutritional, mineral supplementation is a necessary practice because, in general, the diets did not contain these elements in sufficient quantity to meet the needs of poultry. Zinc is a trace mineral essential to life, participating in several important functions in the body. Generally zinc is added to diets of birds in inorganic forms (oxides, carbonates or sufatos), however in its organic form or chelated presents more bioavailable. The objective of this study was to evaluate the effect of levels of organic zinc (ZnO) in the diet of broilers from 1 to 42 days, housed in new or reused litter. The experiment was conducted in the poultry sector of the Special Unit for Agricultural Sciences EAJ / UFRN. 576 chicks were used 1 day of commercial strain Cobb, distributed in a completely randomized in a 4x2 factorial arrangement with four levels of ZnO 0, 40, 80 and 120 ppm and two environments, new bed (COn) and reused litter (CRE) resulting in eight treatments with six replications of 12 birds. In the pre-initial responses were linearly increasing levels of ZnO on feed intake and quadratic effect on body weight and weight gain. The levels of 72.41 and 70.05 ppm of ZnO in the diet of chicks improved body weight and weight gain, respectively. There was interaction between ZnO and the type of bedding used. The ZnO did not affect broiler performance in the growing phase. There was an interaction between levels of ZnO and type of bed used. The levels of 61.50 and 85.30 ppm organic zinc improves immunity and increases the deposition of zinc in tibia of broilers at 42 days, respectively. ZnO also increases the resistance of the skin of broilers at 42 days of age. Using Cre improves performance of broilers from 1 to 42 days old