42 resultados para Engenharia de cristais


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The struvite precipitation in wastewater treatments plants offer advantages to obtaining a economically viable product, containing phosphorus, nitrogen and magnesium, in a bioavailable conditions to plants. The precipitation process requires ideal conditions, but all of these aspects are difficult to obtain and may result in resistance to collect crystals during the sedimentation process. Therefore, instead find the best conditions for precipitation, we propose the dissolved air flotation as another method to retrieve the crystals. The application of dissolved air flotation method to promote separation of struvite crystals from sewage supernatant, was evaluated in a precipitation-flotation reactor (flotatest) and were compared with the precipitation-sedimentation assays (jar test). Finally, were observed that the dissolved air flotation process was as feasible as sedimentation to promote struvite crystals separation, and the pH are the most influencer factor for an efficient separation

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This study addresses the question of attraction and retention of talent in companies that produce engineering projects in the area of oil and natural gas in the city of Natal. The objectives were to identify the mechanisms that these companies use to attract and retain talented professionals and what the relationship between these practices and performance of these organizations in the market. This is a case study of a qualitative nature which were included in the fullness of companies that work in that class in the capital Potiguar. Have been applied to the managers of these companies structured questionnaires with eleven issues orientativas based on theoretical reference adopted. The research finds that managers understand the word "talent", recognize the importance of the appreciation of its employees and the development of their innate abilities to better organizational performance, much due to the fact they are acting in a market of fierce competition. His companies - though not submit the formal procedures related to the subject in question - have mechanisms that can be characterized as the attraction and retention of talent. The relationships identified in this study are consistent with the results found in other studies and put the information here can serve as the basis for that other managers, including other areas, to reach excellence in their respective industries

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Droughts surfaced in 1877 as a crucial problem for the birthing Brazilian nation. Engineers, who formed the country's technical and scientific elite, took it upon themselves to study, understand and fight the problem through planned actions of intervention on space. This work, based on proposals and discussions contained in engineering magazines and reports, aims to provide elements for the comprehension of how these systematized actions against droughts, in the Iate nineteenth and early twentieth century, contributed to spatial analysis and the formation of a (then-inexistent) regional and territorial planning discipline in Brazi!. Engineers, by taking up the position of masterminds in the country's modernization, guaranteed for themselves personal economic stability, social prestige and political power. By understanding nature, either as a resource to be exploited or an adversary to national progress, they contributed to the delimitation of the region now known as the Northeast. By seeking to understand the drought phenomenon, they created knowledge about the space they sought to intervene on; by constructing their projects amid political and economical difficulty, they changed the organizational structures of cities and country in the northeast. The proposals for açudes (Iarge water reservoirs) allowed the fixation of population and the resistance against droughts; the roads - railroads and automotive roadways - connected the sertão to the capitais and the coast, speeding up help to the affected populations during droughts and allowing the circulation of goods so as to strengthen the local economies in normal rimes. The adopted practices and techniques, adapted from foreign experience and developed through trial and improvement, were consolidated as an eminently spatial intervention course, even if a theoretical body of regional or territorial planning wasn't formed in Brazil. Regional Planning proper was first applied in the country in the Northeast itself, in the 1950s, based off an economical view of reality in order to achieve development. The engineer's work prior tothat date, however, cannot be dlsconsldered. It was proved that, despite facing financial and political hurdles, engineers had a profound commitment to the problem and intended to act systematically to transform the economical and social relations in the region, in order to be victorious in their struggle against droughts

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

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The environmental impacts, caused by the solid residues generation, are an often quoted concern nowadays. Some of these residues, which are originated from different human activities, can be fully reused, reducing the effects of the poor waste management on the environment. During the salt production process, the first formed crystals are discarded as industrial waste. This is mainly made of gypsum that is a calcium sulfate dihydrate (CaSO4.2H2O). The gypsum in question may go through a calcination process due to the plaster (CaSO4.0,5H2O) production and then the application on the cement industry. Considering the necessity of development and application for these industrial wastes, this paper aims to analyze the plaster, called Salgesso, from the gypsum that was generated during the salt production, and its use viability on the civil construction industry in order to create environmental and economical benefits. For characterization, the following experiments were performed: X-ray Fluorescence (XRF), X-ray Diffraction (XRD), thermal analysis (TG/DTG) and Scanning Electron Microscopy (SEM) with EDS. The following tests were also performed to obtain the mechanical characteristics: Thinness Modulus, Unit Mass, Setting Time and Compressive Resistance. Three commercial plasters used on civil construction were taken as references. All of these tests were performed according to the current standards. It was noticed that although there were some conflicting findings between the salt and commercial plasters in all of the studied properties, the Salgesso has its values within the standard limits. However, there is the possibility to improve them by doing a more effective calcination process. Three commercial plasters, used in construction, were used as reference material. All tests were performed according to standards in force. It was observed that although some tests present conflicting findings between the salt and gypsum plasters commercial properties in all of the studied Salgesso have values within the limits imposed by the standard, but can be improved simply by calcination process more effective

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The general objective of this study was to contribute to the understanding of the chemical evolution of fluids that percolate through carbonate rocks of the Jandaíra Formation. The oxidation and reduction conditions in which grains, source and cement were formed was investigated using the cathodoluminescence technique (CL). The study area is located in the west part of the Potiguar Basin (Fazenda Belém field) and Rosário Ledge (Felipe Guerra municipality, State of Rio Grande do Norte, Brazil). The analysis of thin sections of carbonate rocks under CL revealed that grains (allochemical or not) and diagenetic products (micritization, dolomitization, neomorphism and cementation) exhibit since absence of luminescence the various luminescence colors (yellow, orange, red, brown, and blue) in a variety of intensities. As pure calcite shows dark blue luminescence, the occurrence of different luminescence colors in calcite crystals suggest one or more punctual crystal defects such as free electron, free space and impurity. The dyeing of thin sections with alizarin and potassium ferrocyanide revealed the absence of ferrous carbonate in the different lithotypes of Jandaíra Formation. Therefore, the different colors and intensities of CL observed in these rocks are probably caused by the presence of ion activators such as Mn2+ and is not an activator/inhibitor combination. In the same way, the absence of luminescence is very probably caused by the absence of activator ions and not due to the low concentration of inhibitor ions such as Fe2+. The incorporation of Mn2+ in the different members of the Jandaíra Formation must have been controlled by the redox state of the depositional environment and diagenesis. Therefore, it is possible that the luminescent members have been formed (e.g.,ooids) or have been modified (gastropod neomorphism) under reduction conditions in the depositional environments, in subsurface during the burial, or, in the case of Rosario Ledge samples , during the post-burial return to surface conditions. As regards the sudden changes from low to moderate and to strong luminescence, these features should indicate the precipitation of a fluid with chemical fluctuations, which formed the frequent zonations in the block cement of the Rosario Ledge samples. This study suggests that the different intensities and colors of CL should be correlated with the Mn2+ and Fe2+ contents, and stable isotopes of samples to determine the salinity, temperature, pH e Eh conditions during deposition

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The purpose of this dissertation is to formulate guidelines for the improvement of maturity models, or the development of new ones, aiming at its application to project departments. The maturity of project management has become critical for organizations that develop projects and want to stand out in the market they serve. For this purpose, maturity models provide paths in order to guarantee that the institutionalization of project management is achieved in the best possible way. Generally, these models assess the organization, define its current situation in managing projects and propose steps to be performed in the search of more advanced levels of maturity. With the objective of contributing to the improvement of maturity models for specific cases, a bibliographical research was conducted for the preparation of a comparative analysis matrix and performed a case study for application of two maturity models (MMGP and PMMM levels 2 and 3), selected based on criteria found in the literature, in an engineering department of an oil company. The case study supported the realization of a comparative analysis of models, from which guidelines were formulated for improvement. The results showed that thedepartment is evaluated in a medium stage of maturity, recording significant progress in some dimensions assessed. They also found that the results of applying the two models are presented as complementary, although the model is highlighted by the greater depth of MMGP diagnostic, considering many variables in their levels of maturity than model PMMM (levels 2 and 3).Finally, directions have been formulated that contribute to the improvement of maturity models, taking in account the organizational environment in which this work was developed

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This thesis aims at analyzing the perspective of graduates perceived quality of an undergraduate course in order to contribute to continuous improvement. In order to achieve the proposed objectives, we performed a literature search, seeking together the work surrounding this issue, with the intent to update the concepts discussed today on the subject studied, they are: quality management, quality in higher education institutions and the system national assessment of higher education - Sinaes. The methodology is characterized as a case study, quantitative, and the object of study is composed of students who graduated from Production Engineering, Federal University of Rio Grande do Norte, which includes students who graduated from 2002 to 2010; data collection was done through the survey instrument, questionnaire, available online through SurveyMonkey interface, data analysis was done by means of descriptive statistics and multivariate analysis, including factor analysis. The proposed survey instrument consists of questions nineteen and twenty statements that address the central theme of this dissertation. The results show the identification of four latent factors (obtained by exploratory factor analysis), through two perspectives, the analysis of perception and importance, the results were similar in terms of the variable factors. The first factor was related to the support given to students, a factor known to support two extra class, the third factor related aspects of the library, and finalizing the evaluation and approached a factor of 4 facilities. Through research it was concluded that this study presents several points to be improved by the management team, and recommended to continue to evaluate the perceptions of graduates, seeking continuous improvement in service delivery by the university

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

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This Master of Science Thesis deals with applying DEA (Data Envelopment Analysis) to the academic performance evaluation of graduate programs in Brazil, exploring it on a Mechanical and Production Engineering Program 2001-2003 data. The data used is that of the national assessment carried by CAPES, the governmental body in charge for graduate program assessment and certification. It is used the CCR output oriented DEA model, the CCR-Output with Assurance Region, and Window Analysis. The main findings are first that the CCR has the concerning problem of zero values of weights of outputs that is not appropriate in a sense that a graduate program has the higher efficiency score zeroing some output (e.g., number of academic papers published). Secondly, the Assurance Region method proved useful. Third, the Window Analysis also gave some light to the consistency of the performance in the time frame analysed. Also, the analysis results in the understanding that the Mechanics and Production Engineering should not be assessed jointly like currently applied by CAPES and rather should be assessed in its own field separately. Finally, the result of the DEA analysis showed some serious inconsistencies with the CAPES method. Graduate programs considered excellent has got low performance score and vice versa. This Thesis provides a strong argument in order to use DEA at least as a complimentary methodology for graduate program performance evaluation in Brazil

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This research aims at to contribute to show the consolidation of the area of Information Systems (IS) as area of knowledge in Production Engineering. For this, it according to presents a scenery of the publication in IS in the field of the Production Engineering in Brazil amount of articles, the authorship profile, the methodologies, the citations, the research thematic and the continuity of the research thematic. The base for this study was the works published in the National Meeting of Production Engineering - ENEGEP of years 2000, 2001, 2002, 2003 and 2004, inside of the area of Information Systems. Classified as bibliographical research, of applied nature, quantitative boarding, of the point of view of the objectives description-exploration was called and for the collection of data its comment was systematic with bibliographical survey. As field research, the method of collection of data if constituted of the elaboration of an analysis protocol and, to arrive itself at the final diagnosis, it operation the data through the statistical method, with the accomplishment of descriptive analyses. It approached concepts of IS and the seek areas and, it studied research correlate in Production Engineering, in Information Systems, in Information Science and other areas of the knowledge. How much to the results one concluded that the national and international contents are compatible and that the area of IS is in constant evolution. For the continuity of research lines it was observed that the majority of the authors was faithful to the area of Systems of Information. Amongst other found results, some institutions must try to increase its volume of publications and research, while others must look for to keep its reached mark already in the last years

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In the recovering process of oil, rock heterogeneity has a huge impact on how fluids move in the field, defining how much oil can be recovered. In order to study this variability, percolation theory, which describes phenomena involving geometry and connectivity are the bases, is a very useful model. Result of percolation is tridimensional data and have no physical meaning until visualized in form of images or animations. Although a lot of powerful and sophisticated visualization tools have been developed, they focus on generation of planar 2D images. In order to interpret data as they would be in the real world, virtual reality techniques using stereo images could be used. In this work we propose an interactive and helpful tool, named ZSweepVR, based on virtual reality techniques that allows a better comprehension of volumetric data generated by simulation of dynamic percolation. The developed system has the ability to render images using two different techniques: surface rendering and volume rendering. Surface rendering is accomplished by OpenGL directives and volume rendering is accomplished by the Zsweep direct volume rendering engine. In the case of volumetric rendering, we implemented an algorithm to generate stereo images. We also propose enhancements in the original percolation algorithm in order to get a better performance. We applied our developed tools to a mature field database, obtaining satisfactory results. The use of stereoscopic and volumetric images brought valuable contributions for the interpretation and clustering formation analysis in percolation, what certainly could lead to better decisions about the exploration and recovery process in oil fields

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The main purpose of this dissertation, consists of the study and analysis of the PBG (Photonic Band Gap )..tecnology incorporated in optical fiber structures. So, we'l1 present a complete PBG structure theory, and folowing this, we'l1 present also a chapter for convencional optical fiber, due to the need to construct the base theory of them, and latter a more complete work about photonic crystal fiber. Finaly, we'l1 show the results of the signals , dispersion, and obtained curves under the right dimensions according to the required signals, for convencional optical and photonic crystal fiber. Knowing that PBG crystals with low losses act as perfect mirrors for forbidden frequences and knowing that the persence of structures of PBG as substrates, brings some desirable characteristics such as spontaneous emition supression and superficial waves. We' 11 show according to these characteristics its applications in telecomunication. Therefore, the enphasis of this work is to show that the optical fibers are the only practible thing to integrate the enormous quantity of data and video at intemet' s market, developing, manipulating, changing, and multiplexing the optical fibers chanels in an area where we expect that the photonic crystals has an important hole, since the photonic crystals can be projected and made to avoid losses in the bands of certain wavelength which permits the increase in efficiency ofthe optical components projected with crystals. A sequence of this work would be the utilisation of the PBG structures in the new system of optical network without fiber developed by Bell laboratories of the lucent tecnology, last year using light rays for transmiting information through the air. The new system of optical networks without fiber will permit sending the data of 15 cd-rooms in less then one second, what represents 65 times more information than those transmitted through the actual radio frequences

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The manufacturing of above and below-knee prosthesis starts by taking surfac measurements of the patient s residual limb. This demands the making of a cartridg with appropriate fitting and customized to the profile of each patient. The traditiona process in public hospitals in Brazil begins with the completion of a record file (according to law nº388, of July 28, 1999 by the ministry of the health) for obtaining o the prosthesis, where it is identified the amputation level, equipment type, fitting type material, measures etc. Nowadays, that work is covered by the Brazilian Nationa Health Service (SUS) and is accomplished in a manual way being used commo measuring tapes characterizing a quite rudimentary, handmade work and without an accuracy.In this dissertation it is presented the development of a computer integrate tool that it include CAD theory, for visualization of both above and below-knee prosthesis in 3D (i.e. OrtoCAD), as well as, the design and the construction a low cos electro-mechanic 3D scanner (EMS). This apparatus is capable to automatically obtain geometric information of the stump or of the healthy leg while ensuring smalle uncertainty degree for all measurements. The methodology is based on reverse engineering concepts so that the EMS output is fed into the above mentioned academi CAD software in charge of the 3D computer graphics reconstruction of the residualimb s negative plaster cast or even the healthy leg s mirror image. The obtained results demonstrate that the proposed model is valid, because it allows the structura analysis to be performed based on the requested loads, boundary conditions, material chosen and wall thickness. Furthermore it allows the manufacturing of a prosthesis cartridge meeting high accuracy engineering patterns with consequent improvement in the quality of the overall production process

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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.