10 resultados para wear strengthening and toughening

em Universidade Federal do Rio Grande do Norte(UFRN)


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OSAN, R. , TORT, A. B. L. , AMARAL, O. B. . A mismatch-based model for memory reconsolidation and extinction in attractor networks. Plos One, v. 6, p. e23113, 2011.

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OSAN, R. , TORT, A. B. L. , AMARAL, O. B. . A mismatch-based model for memory reconsolidation and extinction in attractor networks. Plos One, v. 6, p. e23113, 2011.

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In the passage of life, the labyrinth of songs and corners are propitious ways for a better comprehension, perception and incorporation of learnings that emerge from our subjectiveness in a magic caught by senses. Eyesight, taste, hearing, touch and smell in communication with the world, put us in front of cultural diversities. The ludicity accumulated by experiences promote the flow of hilarious and concrete discoveries that express themselves in work and leisure demonstrations. Such reflections emerge indicators to the problematic construction centralized in the incorporation of cultural experience knowledge to the formation process and professional interventions in this rule and area. From this significant problematic, aiming to deepen studies, we favored leisure as field of investigative production in full expansion. This, for sure, was an exercise of qualification that guided us through meander of education and made us dip into studies about the corporeity. A research in which the scenery was painted and constructed with the complicity of the culture lived with shine, colors, rhythm and drummings of one of the most present cultural cycles: carnival. Recognized as a stimulant for beauty, participation, socialization, and helped us to enter in the essence of gestures and expressions of corporeity, to think, elaborate and socialize a critic-scientific knowledge which, appropriating from the rhythm of colors, of sounds, of tonalities, of senses and of meanings impregnated in the web of life. All these things seduced the researcher, making imagination flow amid ludic-creative dialogues with the imaginary of researchers creation and production in the rule and area of leisure, education and corporeity. Option that made us outline as objective to investigate and interpret how leisure teachers-researchers, from their studies, researches and interventions, locate and incorporate the knowledge from cultural experience to the formation process and intervention of professionals in this rule and in this area, emphasizing the contributions from this knowledge to fence and qualify this praxis. So, as living each cultural scenery, each epistemological contribution was feeding the production with images of the different versions of the Brazilian breedings, creating and raising expectations and new discoveries and newcomers. With the seriousness of a scientific study, we lived an xxiii academic experience with complex intensity, rigor and coherence, eliminating, step by step, the risks and limitations always present in a work of this magnitude. However, we weren t, even for one moment, alone. Our epistemic regard always maintained mediated by the principles of a methodological approach - the Etnomethodology, that while central guide provided us clues to unveil the lived world by our people-playful , in a universe of 15 members, that allowed themselves to comprehend, comment, analyze. This way, grasping the object in interactions arised and provoked by narrative interview, it was systematically dialected by (re) interpretation of images and formulations of people-playful, enriched by their beliefs, myths, conceptions and rituals inherent to knowledge from cultural experience, which each one attuned with Brazilian and international history, in a mixture of senses echoed from songs and tales. Inspired in drummings and percussions, clothing and choreographies of gestures and expressions, in mixtures produced in unit interactions in the multiplicity shown as necessary requests to the totality of life, with ludicity the rescue of the past, the conquest of present and the construction of future was the axle guide. This rich process of scientific creation made us realize that is possible qualify and empower the praxis in the rule and area of leisure incorporating the knowledge from cultural experience. What also becomes possible is the recuperation of objective revolutionaries and changing conditions of praxis itself with the view of strengthening and triggerment of vital elements in the rule and area of leisure. We also reaffirm that from this praxis emerge elements necessary to human formation in plenitude, by the appropriation of knowledge that guide the facing of challenges of a complex and plural world that valorize education, corporeity and leisure

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Comprehending social representations of users relatives of Psychosocial Care Centers (CAPS) from Natal-RN, about their participation in the activities of these services, was the purpose of this study. The research instrument used was a semi-structured interview, led to 28 relatives of users of East and West CAPS II, East and North CAPS-ad, involved in the Relative Therapeutic Group, in Relative Meeting, in the Assembly of Users, Technicians and Relatives, according to the therapeutic schedule of each health services, between August to November 2007. Data obtained in family and users identification were characterized with the aid of charts and boards in absolute and/or percentage values. The discursive material from the guide from interviews was submitted to the informational resource ALCESTE (Analyse Lexicale par Contexte d'un Ensemble of Segments of Texte), and analyzed on the basis of the Theory of Social Representations and Central Nucleus Theory. Most of the relatives were women, married, aged over 50 years, who participated for more than two years in CAPS activities, and a coexistence of more than 11 years with the user. From the classification system of ALCESTE were selected categories, identified by: Category 1, Treatment Improvements and Expectations; Category 2, Living User Before and After; Category 3, Activities Relevance, Contradictions and Suggestions; Category 4, Guidelines -- Psychopharmacology and Medicalization; Category 5, Family Participation and Activities; and Category 6, Therapeutic Conditions Thanks, Tips and Vulnerability. The social representation of the family exists in the desire for change, identifying that we need to promote change by the continuity of therapeutic activities and overcome the detected inconsistencies, targeted by strengthening and by the stability of improvements in living and health conditions of users, experienced in CAPS treatment. The central nucleus had corresponded to positive changes in health and living conditions of users, and the peripheral elements were constituted by family conducts before and during treatment, and the expectations of changes in activities, especially in workshops. Despite this family participation be considered important, it still does not meet conditions to promote the inclusion of family, under an emancipating point of view, capable of causing in subject the hope for autonomy, initiative, individual and collective growths, a closer and active involvement in therapeutic activities, in workshops and discussions

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Hard metals are the composite developed in 1923 by Karl Schröter, with wide application because high hardness, wear resistance and toughness. It is compound by a brittle phase WC and a ductile phase Co. Mechanical properties of hardmetals are strongly dependent on the microstructure of the WC Co, and additionally affected by the microstructure of WC powders before sintering. An important feature is that the toughness and the hardness increase simultaneously with the refining of WC. Therefore, development of nanostructured WC Co hardmetal has been extensively studied. There are many methods to manufacture WC-Co hard metals, including spraying conversion process, co-precipitation, displacement reaction process, mechanochemical synthesis and high energy ball milling. High energy ball milling is a simple and efficient way of manufacturing the fine powder with nanostructure. In this process, the continuous impacts on the powders promote pronounced changes and the brittle phase is refined until nanometric scale, bring into ductile matrix, and this ductile phase is deformed, re-welded and hardened. The goal of this work was investigate the effects of highenergy milling time in the micro structural changes in the WC-Co particulate composite, particularly in the refinement of the crystallite size and lattice strain. The starting powders were WC (average particle size D50 0.87 μm) supplied by Wolfram, Berglau-u. Hutten - GMBH and Co (average particle size D50 0.93 μm) supplied by H.C.Starck. Mixing 90% WC and 10% Co in planetary ball milling at 2, 10, 20, 50, 70, 100 and 150 hours, BPR 15:1, 400 rpm. The starting powders and the milled particulate composite samples were characterized by X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) to identify phases and morphology. The crystallite size and lattice strain were measured by Rietveld s method. This procedure allowed obtaining more precise information about the influence of each one in the microstructure. The results show that high energy milling is efficient manufacturing process of WC-Co composite, and the milling time have great influence in the microstructure of the final particles, crushing and dispersing the finely WC nanometric order in the Co particles

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Present work proposed to map and features the wear mechanisms of structural polymers of engineering derived of the sliding contact with a metallic cylindrical spindle submitted to eccentricity due to fluctuations in it is mass and geometric centers. For this it was projected and makes an experimental apparatus from balancing machine where the cylindrical counterbody was supported in two bearings and the polymeric coupon was situated in a holder with freedom of displacement along counterbody. Thus, the experimental tests were standardized using two position of the two bearings (Fixed or Free) and seven different positions along the counterbody, that permit print different conditions to the stiffness from system. Others parameters as applied normal load, sliding velocity and distance were fixed. In this investigation it was used as coupon two structural polymers of wide quotidian use, PTFE (polytetrafluroethylene) and PEEK (poly-ether-ether-ketone) and the AISI 4140 alloy steel as counterbody. Polymeric materials were characterized by thermal analysis (thermogravimetric, differential scanning calorimetry and dynamic-mechanical), hardness and rays-X diffractometry. While the metallic material was submitted at hardness, mechanical resistance tests and metallographic analysis. During the tribological tests were recorded the heating response with thermometers, yonder overall velocity vibration (VGV) and the acceleration using accelerometers. After tests the wear surface of the coupons were analyzed using a Scanning Electronic Microscopy (SEM) to morphological analysis and spectroscopy EDS to microanalysis. Moreover the roughness of the counterbody was characterized before and after the tribological tests. It was observed that the tribological response of the polymers were different in function of their distinct molecular structure. It were identified the predominant wear mechanisms in each polymer. The VGV of the PTFE was smaller than PEEK, in the condition of minimum stiffness, in function of the higher loss coefficient of that polymer. Wear rate of the PTFE was more of a magnitude order higher than PEEK. With the results was possible developed a correlation between the wear rate and parameter (E/ρ)1/2 (Young modulus, E, density, ρ), proportional at longitudinal elastic wave velocity in the material.

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The present work consists in the analysis of tribologycal properties of basic and multifunctional knitted fabrics. This knowledge has fundamental importance for the textile industry since it can quantify, in an objective way, the tactil. The fabrics used were characterized by friction and mechanical tests for determining the viscoelastic region, wear resistance and friction coefficient of the fabrics used. The stress-strain curve was obtained by the method Kawabata, KES-FB1. Wear tests performed with the aid of equipment Martindale. The measurement of friction coefficient, two methods were used and analyzed comparatively. The first was a method already established worldwide known as KES-FB4 and the second was an innovative method called FRICTORQ, developed by the University of Minho. These two methods were compared taking into account the relative motion between the tribologycal pairs are different from each method. While the first motion is translational, the second is rotational. It was formal that the knitted had a multifunctional fabrics tribologycal performance which was better than the basic knitted fabrics, as the viscoelastic region, was laager highlighting a multifunctional structure, with greater wear resistance mainly on the back side of the knitted fabrics and lower friction coefficient. Performing a comparative analysis between two methods used to measure the friction coefficient, it was formal that both methods were consistent in terms of results. In operational terms, the FRICTORQ showed ease of operation and increased reproducibility of results

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Wear mechanisms and thermal history of two non-conforming sliding surfaces was investigated in laboratory. A micro-abrasion testing setup was used but the traditional rotative sphere method was substituted by a cylindrical surface of revolution which included seven sharp angles varying between 15o to 180o. The micro-abrasion tests lead to the investigation on the polyurethane response at different contact pressures. For these turned counterfaces with and without heat treatment. Normal load and sliding speeds were changed. The sliding distance was fixed at 5 km in each test. The room and contact temperatures were measured during the tests. The polyurethane was characterized using tensile testing, hardness Shore A measurement, Thermogravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC) and Thermomechanical Analyze (TMA). The Vickers micro-hardness of the steel was measured before and after the heat treatment and the metallographic characterization was also carried out. Worn surface of polyurethane was analysed using Scanning Electron Microscope (SEM) and EDS (Electron Diffraction Scanning) microanalyses. Single pass scratch testing in polyurethane using indenters with different contact angles was also carried out. The scar morphology of the wear, the wear mechanism and the thermal response were analyzed in order to correlate the conditions imposed by the pressure-velocity pair to the materials in contact. Eight different wear mechanisms were identified on the polyurethane surface. It was found correlation between the temperature variation and the wear scar morphology.

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Since the 1970s, Brazil has gone through several changes in its economic and productive structures, which have symbiotic relationship with the organization and dynamics of the Brazilian territory. This set of economic, social and technical-scientific transformations developed in the amid the productive capital restructuring, a process that occurs on a global scale, but that effective with particularities in different places. Adopting this presuposition the present research had as main objective analyze the productive restructuring of the dairy sector in Rio Grande do Norte, highlighting its relationship with production process / organization of space and its impact on the social relations of production. The adopted methodology to elaborate of this study was based on the achievement a bibliographic review with regard to proceedings of production of space and productive restructuring, document research about the dynamics of the dairy sector in Rio Grande do Norte, as well as on regulatory instructions governing the dairy production in Brazil, we achieve parallel secondary data collection, with official organs such as IBGE, EMATER and SINDLEITE. Another important methodological resource was the realization of the field research, which enabled us to empirically understand the distinct realities lived by agents acting on milk production system in Rio Grande do Norte. The analyzes performed nevertheless evidence that the restructuring process in the dairy sector is fomented, greatly by state,that finance, encourages and normatizes the production of milk in the country. In the specific case of Rio Grande do Norte, this process is boosted by the creation of "Programa do Leite," which by constituting of an institutional market, contributes to the strengthening and expansion of industries, the detriment of the artisanal processing sector. Nevertheless family farmers continue to act in the activity, be only producing and trading fresh milk, supplying milk to processing units, mediating the production of their peers or by the craft benefiting milk in traditional cheese factories presents in the entire state of Rio Grande do Norte. The results reveal that it is a complex web of social relations of production that are established at the heart of laticinista activity in the Rio Grande Norte, these are summarily marked by relations of competition and complementarity between industrial and artisanal processing of milk

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This master thesis has the main goal investigate how families are inserted in the socioeducational process of teenagers who are undergoing social measures of liberty deprivation. The specific objectives are: to characterize the family´s living together of adolescents deprived of their freedom and their families, from the actions and routines of the socio-educational system; to assess the professional working links in the context of socio-education, in order to care and strengthening families of the adolescents; to investigate how families evaluate the operation of socio-educational process in which adolescents are met. Method: to achieve the proposed objectives, data collection occurred in complementary steps: the first phase took place from visits to socioeducational units of liberty deprivation of RN, and dialogues with professionals working in socio-education. Subsequently, action research stage was carried out, from the insertion of the researcher in the extension project Family and the struggle for the effectiveness of the National Socio Service System, that aimed to strengthen monitoring the adolescents socio-education by their families, and had as methodology the conversation circles and thematic workshops. Lastly, were performed reading and analysis of the references to the family in the Individual Care Plans (PIAs) for adolescents. The information gathered was recorded in field diaries and subjected to thematic content analysis. This research was guided by the Marxist theoretical framework, structured on the understanding of the involvement of adolescents with illegal acts as a development and expression of the social question. From this theoretical framework, the prevailing view in the capitalist society of adolescents in conflict with the law as individuals who are treated by means of repression and segregation and the weakness of social policies is questioned, both in the execution of their own socioeducational measures as the articulation of network services for adolescent protection and strengthening your family. Results: in relation to the operation of the socioeducational system in RN in general, it was observed a state of unhealthy physical spaces and institutional practices that violate human rights, idleness and lack of access to social rights, and criminalization and institutionalization of poor young people and their families. With regard to family´s living together, it was noticed great distance between principles and guidelines recommended by the SINASE, about acquaintanceship and family strengthening, and every day practices of socio-education in RN: serious violations were observed that undermine the family´s living together, as the distance between the socio-educational units of deprivation of liberty and the cities where families live; absence, irregularity and poor conditions in carrying out the family visits; lack of conjugal visits; restricted and unarticulated actions for the care and strengthening of the families of adolescents, most of whom live in poverty or extreme poverty. Finally, it was found a number of blamefully and punishments to the family, including practices such as inward inspection (visual inspection while naked and squant), plus a series of violence and omissions care that sick family members and weaken the links between adolescents and their families.