Comportamento magnético de compósitos de matriz polimérica com adição de ferritas

Polymer matrix composites offer advantages for many applications due their combination of properties, which includes low density, high specific strength and modulus of elasticity and corrosion resistance. However, the application of non-destructive techniques using magnetic sensors for the evaluation these materials is not possible since the materials are non-magnetizable. Ferrites are materials with excellent magnetic properties, chemical stability and corrosion resistance. Due to these properties, these materials are promising for the development of polymer composites with magnetic properties. In this work, glass fiber / epoxy circular plates were produced with 10 wt% of cobalt or barium ferrite particles. The cobalt ferrite was synthesized by the Pechini method. The commercial barium ferrite was subjected to a milling process to study the effect of particle size on the magnetic properties of the material. The characterization of the ferrites was carried out by x-ray diffraction (XRD), field emission gun scanning electron microscopy (FEG-SEM) and vibrating sample magnetometry (VSM). Circular notches of 1, 5 and 10 mm diameter were introduced in the composite plates using a drill bit for the non-destructive evaluation by the technique of magnetic flux leakage (MFL). The results indicated that the magnetic signals measured in plates with barium ferrite without milling and cobalt ferrite showed good correlation with the presence of notches. The milling process for 12 h and 20 h did not contribute to improve the identification of smaller size notches (1 mm). However, the smaller particle size produced smoother magnetic curves, with fewer discontinuities and improved signal-to-noise ratio. In summary, the results suggest that the proposed approach has great potential for the detection of damage in polymer composites structures

Design gráfico da pluma de contaminação por compostos orgânicos voláteiss utilizando software CAD na investigação de passivo ambiental em um posto revendedor de combustíveis em Natal/RN

Among the potentially polluting economic activities that compromise the quality of groundwater are the gas stations. The city of Natal has about 120 gas stations, of which only has an environmental license for operation. Discontinuities in the offices were notified by the Public Ministry of Rio Grande do Norte to carry out the environmental adaptations, among which is the investigation of environmental liabilities. The preliminary and confirmatory stages of this investigation consisted in the evaluation of soil gas surveys with two confirmatory chemical analysis of BTEX, PAH and TPH. To get a good evaluation and interpretation of results obtained in the field, it became necessary three-dimensional representation of them. We used a CAD software to graph the equipment installed in a retail service station fuel in Natal, as well as the plumes of contamination by volatile organic compounds. The tool was concluded that contamination is not located in the current system of underground storage of fuel development, but reflects the historical past in which tanks were removed not tight gasoline and diesel

Universidade e educação ambiental

The society consists of the inter-relations between diverse symbolic fields of performance, where some agents if identify for values, habits and goals. The present thesis analyzed, taking for base the Theory of the Social Field of Pierre Bourdieu, the ambient field and the university, leaving of the principle that the university is one of the propitious places for the quarrel, study, knowledge elaboration, and that the ambient education is one of the ways of dissemination of knowledge and action in favor of the ambient question. It was looked to contextualize and to identify the main factors that configure the university while a social field, and to evidence the conflict and connector links with the ambientalism. It is perceived university as space of tensions, whose produced capital stock in the academic scope must be enough convincing in the direction of the social transformation, of the expansion of conscience, the critical matureness, and thus to appear as agent of social transformation. The joint between the diverse social fields, promoted for the university, will be able to contribute for knowledge formularization that can consist base for elaboration of politics and programs to answer to the problems of the society contemporary. It has the inter-relationship between the two fields, however, this relation still is fragile, needing that a continuity practical social that they make possible that the ambient question is part of the culture of the university. This will be able to give with the intensification of the actions and the inclusion of the ambient questions in the communication mechanisms and administrative management. To surpass discontinuities caused for changes of groups leading and for interests politician conjunctural are necessary that they create habitus, what passes for the institutionalization of practical and the constitution of a culture that the agents allow if to reorganize defending the interests of social transformation front to the economic interests, as much in the university how much in the ambient field

Avaliação do programa escola ativa como política pública para escolas do campo com turmas multisseriadas: a experiência em jardim do seridó/rn (1998-2009)

This work aims at developing an evaluation of the implementation of the Program Escola Ativa as a public policy for rural schools with combined grade classrooms in Jardim do Seridó RN (1998 2009) focusing on the following dimensions: school s physical environment, training, follow up, and didactic usage of the methodology. In order to develop this research we refer to the literature that analyzes the cycle of policies (FREY, 2000). In this approach, evaluation represents an important step in the process of analyzing the implementation of public policies, as a way of measuring up their performance, as well as a guide for realignments and redefinitions (PRESSMAN; WILDAVSKY, 1998). In order to accomplish this function, the evaluator of policies must be acquainted with scientific concepts and methods that consist of describing, interpreting and analyzing the policies in the governmental sphere (MENY; THOENIG, 1992; LIMA JÚNIOR, 1978). In this perspective, we intend to investigate whether in its proposition of minimizing the blanks in the Brazilian educational system, the implementation of the Program would be contributing to the improvement of the political-pedagogical practices in the rural schools with combined grade classrooms in Jardim do Seridó RN. In order to do this research, we have developed a theoretical-methodological matrix made of analysis dimensions, variables, indicators and instruments, such as literary revision, documental analysis, semi-structured interviews with four teachers and three supervisors that work and/or have worked in Escola Ativa in that town in the period comprised among 1998 2009, besides notes taken from field observation and photographs from four rural schools with combined grade classrooms. With this research we have identified that the Program, at a national level, has gone through different phases in its implementation process, for the town was not ready to fully take the responsibilities of the autonomous expansion, in 2002. From that period on, the execution of Escola Ativa has suffered several discontinuities, such as the lack of professional training and supervising. It is also noted that the methodology contributes to the dynamization of the didactic-pedagogical activities and promotes the cooperation and autonomy of the students in the organization and the applicability of the components of the curriculum, especially of Governo Estudantil and Cantinhos de Aprendizagem. Although the directions of the Program (BRASIL, 2005) point out that Escola Ativa has among its principles social transformation, we identified that, isolated, the initiative is not capable of promoting the changes that the rural schools need, namely investments in the physical, material, pedagogical and technological infra-structure, besides the estimation and a career plan for the teachers. In a general draft of the results of this research, we realized that some aspects presented about the peculiarities of Escola Ativa in Jardim do Seridó as a governmental Program, reinforce the need for the public policies to be evaluated, in order to confront critic and operationally the planning with the practice, revising action, whenever necessary

CORPOREIDADE E A MELODIA DA EXPERIÊNCIA ESTÉTICA NA FORMAÇÃO HUMANESCENTE DE CANTORES-EDUCADORES

In order for this study to be developed, the central goal on our investigation was defined as analyzing and interpreting the aesthetical experiences meanings lived by singers-educators in the human formation. The interest for the aesthetical experience theme was built from my own experience for the last twelve years as a member of the School of Music Madrigal, the oldest group in the State Federal University, created for research and cultural extension with structural perspective which brings closer teachers, students and the outer community that comes from different social realities to face the challenge of combining the ability of singing, the corporeity involvement and the aesthetical experiences meanings. This paper points out the understanding of art as perceptive expression of human emotions, such as the creation of existential demand, the restructuring of oneself and the constructions which shape beauty. We seek a dense contribution of new challenges to the peculiar demand of human potential in terms of sensibility repertoire, of involvement, of expectation in magnifying the possibilities and the human and social competences. In the formation human process, we find a living field blooming with natural artistical possibilities, experimenting emotions and feelings shared in collective life, and bringing out impulses to unexpected ludic creation, establishing a powerful aesthetical ambience which highlights the symbolic and imaginary with the deepening of rich ludopoiese properties in several meanings. From the guiding principles of etnophenomenology we find structural and indispensable perspectives which contemplate values, desires, archtype images and ideas that impress originality and fertility to the study. On this path we understand the abundance of living moments of intense commitment, acquaintance, challenges, reunions and connections that stand out from fundamental aspects to freedom, autonomy, creativity and new discontinuities. This acknowledgement brings us closer to the enlighted fullness which makes us humans

Body art, existência e conhecimento :a percepção do corpo na Educação Física

In the Renaissance, the anatomy project a map of the body. Since then, the human body has been investigated for innumerable techniques, configuring new landscapes on the condition human being and the proper knowledge. In accordance with Merleau-Ponty (1975), All technique is body technique. It configures and extends the Metaphysical structure of our meat. In this direction, any intervention in the human body, a tattooing, a surgery or a performance, extends the perception and the directions of the existence of the subject. Merleau-Ponty (1975) still affirms, that all technique presents objective interventions. However, the body, ahead of these interventions, doesn t have to be considered only object, but subject that, from the interventions, attributes sensible and meanings through the movements, also being this its way of being in the world. Searching to extend this reflection on the discontinuities between the object body and the subject body, as well as, with the objective to reflect on the relation between the corporal techniques and the production of the subjectivity and the knowledge of the physical education, we reflect on the body art, as one technique of body that marks the exterior of the body, exteriorizing the subjectivity, to search new means to the body and that ahead of this, we believe being able to project innumerable directions for the corporal transformations in the contemporarily. As a method for our reflection in we will support them in the phenomenology. IT presents as a new ontology, in which distinction does not occur enters the operating paper of the citizen that knows and the influence of the known object. The phenomenological understanding of body will be able to contribute with the knowledge of the Physical Education, a time that gives us important arguments on the experience of the body in relation with the nature, the culture, history. To be a body is to be tied to a world that we do not possess completive, but that we do not cease to search it

Localização de faltas em linhas de transmissão de múltiplos terminais a partir de registros oscilográficos sincronizados via transformada wavelet

The electric energy is essential to the development of modern society and its increasing demand in recent years, effect from population and economic growth, becomes the companies more interested in the quality and continuity of supply, factors regulated by ANEEL (Agência Nacional de Energia Elétrica). These factors must be attended when a permanent fault occurs in the system, where the defect location that caused the power interruption should be identified quickly, which is not a simple assignment because the current systems complexity. An example of this occurs in multiple terminals transmission lines, which interconnect existing circuits to feed the demand. These transmission lines have been adopted as a feasible solution to suply loads of magnitudes that do not justify economically the construction of new substations. This paper presents a fault location algorithm for multiple terminals transmission lines - two and three terminals. The location method is based on the use of voltage and current fundamental phasors, as well as the representation of the line through its series impedance. The wavelet transform is an effective mathematical tool in signals analysis with discontinuities and, therefore, is used to synchronize voltage and current data. The Fourier transform is another tool used in this work for extract voltage and current fundamental phasors. Tests to validate the location algorithm applicability used data from faulty signals simulated in ATP (Alternative Transients Program) as well as real data obtained from oscillographic recorders installed on CHESF s lines.

Efeito de adições poliméricas na aderência de pastas de cimento a tubos metálicos após ciclagem térmica

Thermal recovery methods, especially steam injection, have been used to produce heavy oils. However, these methods imply that the metallic casing-cement sheath interface is submitted to thermal cycling. As a consequence, cracking may develop due to the thermal expansion mismatch of such materials, which allows the flow of oil and gas through the cement sheath, with environmental and economical consequences. It is therefore important to anticipate interfacial discontinuities that may arise upon Thermal recovery. The present study reports a simple alternative method to measure the shear strength of casing-sheath interfaces using pushthrough geometry, applied to polymer-containing hardened cement slurries. Polyurethane and recycled tire rubber were added to Portland-bases slurries to improve the fracture energy of intrinsically brittle cement. Samples consisting of metallic casing sections surrounded by hardened polymer-cement composites were prepared and mechanically tested. The effect of thermal cycles was investigated to simulate temperature conditions encountered in steam injection recovery. The results showed that the addition of polyurethane significantly improved the shear strength of the casing-sheath interface. The strength values obtained adding 10% BWOC of polyurethane to a Portland-base slurry more than doubled with respect to that of polyurethane-free slurries. Therefore, the use of polyurethane significantly contributes to reduce the damage caused by thermal cycling to cement sheath, improving the safety conditions of oil wells and the recovery of heavy oils

Laminados compósitos de PRFV: efeitos da descontinuidade geométrica e do envelhecimento ambiental acelerado

The growing demand in the use of composite materials necessitates a better understanding of its behavior related to many conditions of loading and service, as well as under several ways of connections involved in mechanisms of structural projects. Within these project conditions are highlighted the presence of geometrical discontinuities in the area of cross and longitudinal sections of structural elements and environmental conditions of work like UV radiation, moisture, heat, leading to a decrease in final mechanical response of the material. In this sense, this thesis aims to develop studies detailed (experimental and semi-empirical models) the effects caused by the presence of geometric discontinuity, more specifically, a central hole in the longitudinal section (with reduced cross section) and the influence of accelerated environmental aging on the mechanical properties and fracture mechanism of FGRP composite laminates under the action of uniaxial tensile loads. Studies on morphological behavior and structural degradation of composite laminates are performed by macroscopic and microscopic analysis of affected surfaces, in addition to evaluation by the Measurement technique for mass variation (TMVM). The accelerated environmental aging conditions are simulated by aging chamber. To study the simultaneous influence of aging/geometric discontinuity in the mechanical properties of composite laminates, a semiempirical model is proposed and called IE/FCPM Model. For the stress concentration due to the central hole, an analisys by failures criteria were performed by Average-Stress Criterion (ASC) and Point-Stress Criterion (PSC). Two polymeric composite laminates, manufactured industrially were studied: the first is only reinforced by short mats of fiberglass-E (LM) and the second where the reinforced by glass fiber/E comes in the form of bidirectional fabric (LT). In the conception configurations of laminates the anisotropy is crucial to the final mechanical response of the same. Finally, a comparative study of all parameters was performed for a better understanding of the results. How conclusive study, the characteristics of the final fracture of the laminate under all conditions that they were subjected, were analyzed. These analyzes were made at the macroscopic level (scanner) microscope (optical and scanning electron). At the end of the analyzes, it was observed that the degradation process occurs similarly for each composite researched, however, the LM composite compared to composite LT (configurations LT 0/90º and LT ±45º) proved to be more susceptible to loss of mechanical properties in both regarding with the central hole as well to accelerated environmental aging

Descontinuidade na seção transversal em laminados compósitos poliméricos: efeitos e propriedades

The growing demand in the use of composite materials necessitates a better understanding its behavior to many conditions of loading and service, as well as under several ways of connections involved in mechanisms of structural projects. It is know that most of the structural elements are designed with presence of geometric discontinuities (holes, notches, etc) in their longitudinal sections and / or transversals, and that these discontinuities affect the mechanical response of these elements. This work has aims to analyze a study of the mechanical response, when in the presence geometric discontinuity, of polymer matrix composite laminates (orthophthalic polyester) to the uniaxial tensile test. The geometric discontinuity is characterized by the presence of a center hole in the transversal section of the composite. In this study, different kinds of stacking sequences are tested, with and without the presence of the hole, so as to provide better understanding of the mechanical properties. This sense, two laminates were studied: the first is only reinforced by with seven layers short mats of fiberglass-E (CM) and the second where the reinforcement of fiberglass-E comes in the form of bidirectional fabric (CT), with only four layers. The laminate CT has the presence of anisotropy (sense of continuous fibers with respect to the applied load) as the main parameter influencing its mechanical behavior, behavior this, not observed for the CM. In addition to the mechanical properties was also studied the fracture characteristics developed in each composite laminated. The results also showed that the presence of the hole in the transversal section decreased the ultimate strength of laminates and changed the final characteristic of fracture in all kinds of composite laminated studied

Desenvolvimento de um sistema para análise de integridade estrutural de equipamentos estáticos baseado em cad vps micro cracks e ultrassom

In general, the designs of equipment takes into account the effects and processes of deterioration it will undergo and arrives at an approximate useful life. However, changes in operational processes and parameters, the action of external agents, the kind of maintenance conducted, the means of monitoring, and natural and accidental occurrences completely modify the desired performance of the equipment. The discontinuities that occur in anisotropic materials often and due to different factors evolve from being subcritical to critical acquiring the status of defect and compromising the physical integrity of the equipment. Increasingly sophisticated technological means of detection, monitoring and assessment of these discontinuities are required to respond ever more rapidly to the requirements of industry. This paper therefore presents a VPS (Virtual Pipe System) computational tool which uses the results of ultrasonic tests on equipment, plotting the discontinuities found in models created in the CAD and CAE systems, and then simulates the behavior of these defects in the structure to give an instantaneous view of the final behavior. This paper also presents an alternative method of conventional ultrasonic testing which correlates the integrity of an overlay (carbon steel and stainless steel attached by welding) and the reflection of ultrasonic waves coming from the interface between the two metals, thus making it possible to identify cracks in the casing and a shift of the overlay

Compósito Polimérico Híbrido: Comportamento Mecãnico, Descotinuidade Geométrica e Resistência Residual

The growing demand in the use of hybrid composite materials makes it essential a better understanding of their behavior face of various design conditions, such as the presence of geometric discontinuities in the cross section of structural elements. This way, the purpose of this dissertation is a study of the mechanical response (strength and stiffness), modes (characteristics) of fracture and Residual Strength of an hybrid polymeric composite with and without a geometric discontinuity in its longitudinal section (with a reduction in the cross section) loaded by uniaxial tension. This geometric discontinuity is characterized by central holes of different diameters. The hybrid composite was fabricated as laminate (plate) and consisting of ortho-tereftalic polyester matrix reinforced by 04 outer layers of Jute fibers bidirectional fabrics and 01 central layer of E-glass bidirectional fabric. The laminate was industrially manufactured (Tecniplas Nordeste Indústria e Comércio Ltda.), obtained by the hand lay-up technique. Initially, a study of the volumetric density of the laminate was made in order to verify its use in lightweight structures. Also were performed comparative studies on the mechanical properties and fracture modes under the conditions of the specimens without the central hole and with the different holes. For evaluating the possible influence of the holes in the structural stability of the laminate, the Residual Strength of the composite was determined for each case of variation in hole diameter. As a complementary study, analyses of the macroscopic final fracture characteristic of the laminates were developed. The presence of the central hole of any sizes, negatively changed the ultimate tensile strength. Regarding the elastic modulus, moreover, the difference found between the specimens was within the range of tests displacement, showing the laminate stability related to the stiffness

Memórias midiatizadas: percepções sobre ciência reconfiguradas a partir do consumo midiático

This piece focuses on the issue of media in the contemporary context, taking for its object the sociocultural phenomenon of mediatization‟, understood as the dilution of media culture in the everyday life, according to the perspective from Fausto Neto (2008) e Sodré (2002). This phenomenon is viewed from the angle of reception, that is, one that considers the individuals as pro-actives in this dynamic. The media culture is perceived as a fundamental element in the process of social structuring, and also is taken as a symbolic arm of great importance for the elaboration of the notion of reality as it interferes with the flow of information. Thus, we emphasize the process of symbolic consumption that we do with media content (Canclini, 1999), through a dynamic of appropriation and reframing, given from the interweaving of the meanings proposed with extra-media elements, recaptured from the perspective of mediations, by Barbero (2006), which concerns the articulation of the contents we appropriate from media with interactions from other social practices. We also consider the dimension of memory according to Sarlo (2007) and Halbwachs (2004) in order to, through speeches made in its scope, reach empirically the phenomenon of mediatization‟, and overlapping it, the media consumption on a specific theme, "science". Nevertheless, in terms of field work, we use the technique of in-depth interviews, so that the speech of our interviewers was our corpus. Through their narratives, speeches considered by us as memory-related, we visualize the dynamics of media consumption on given topic. At the level of conclusions, we realize that mediatization‟ as a phenomenon occurred, but its flows and orders showed discontinuities and pluralities not initially conceived; regarding the consumption of science through media, we see hybrid perceptions by our respondents, that is, one that include both elements aligned with the positivist conception of science - which we consider to be the view of science proposed by the media and elements that would contradict this view

Análise das curvas de luz do CoroT usando diferentes processos comparativos: estimando períodos de rotação estelar

One of the main goals of CoRoT Natal Team is the determination of rotation period for thousand of stars, a fundamental parameter for the study of stellar evolutionary histories. In order to estimate the rotation period of stars and to understand the associated uncertainties resulting, for example, from discontinuities in the curves and (or) low signal-to-noise ratio, we have compared three different methods for light curves treatment. These methods were applied to many light curves with different characteristics. First, a Visual Analysis was undertaken for each light curve, giving a general perspective on the different phenomena reflected in the curves. The results obtained by this method regarding the rotation period of the star, the presence of spots, or the star nature (binary system or other) were then compared with those obtained by two accurate methods: the CLEANest method, based on the DCDFT (Date Compensated Discrete Fourier Transform), and the Wavelet method, based on the Wavelet Transform. Our results show that all three methods have similar levels of accuracy and can complement each other. Nevertheless, the Wavelet method gives more information about the star, from the wavelet map, showing the variations of frequencies over time in the signal. Finally, we discuss the limitations of these methods, the efficiency to give us informations about the star and the development of tools to integrate different methods into a single analysis

Sobre a relação entre rotação, atividade crosmosférica e abundância de lítio em estrelas subgigantes

The connection between rotation, CaII emission flux and lithium abundance is analyzed for a sample of subgiant stars, with evolutionary status was determined from the Toulouse-Geneve code and HlPPARCOS trigonometric parallax measurements. We noted that the distribution of rotation and CaII emission flux, as a function of effective temperature, shows a discontinuity located around the same spectral type, F8IV. Stars located blueward of this spectral type, exhibit a large spread of values of rotation and CaII flux, whereas stars redward of F8lV show essentially low ratation anel low CaII flux. The strength of these declines nevertheless, depends on stellar mass. The distribution of lithium abundances also shows a discontinuity, however with behavior a little more complex for subgiants with mass lower than about 1.2 Solar Masses, this decrease is observed later than that in rotation and CaII flux, whereas for masses higher than 1.2 Solar Masses the decrease in lithium abundance is located around the spectral type F8IV. The discrepancy between the location of the discontinuities of rotation and CaII flux and log n(Li) for stars with masses lower than 102 Solar Masses, seems to reflect the sensitivity of these phenomena to the mass of the convective envelope. The drop in rotation, which results mostly from a magnetic braking, requires an increase in the mass of the convective envelope less than that required for the decrease in lithium abundance The location of the discontinuity in log n( Li) in the same region of the discontinuity ties in rotation and CaII flux, for stars with masses higher than 1.2 Solar Masses, may also be explained by the behavior of the deepening of the convective envelope. In contrast to the relationship between rotation and CaII flux the relationship between lithium abundance and rotation shows no dear tendency toward linear behavior. Similarly, the same tendency is observed in the relationship between lithium abundance and CaII flux in spite of these facts, subgiants with high lithium content also have high rotation and high CaII emission flux. We also observed that stars with high lithium content present, in its majority, an undeveloped convective envelope, whereas stars with low lithium content have a developed convective envelope. In the case of the rotation, stars with undeveloped convective envelope, show rotational velocities as much high as low, whereas stars with developed convective envelope only present low rotation