103 resultados para Reatores eletrônicos


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Nowadays several electronics devices support digital videos. Some examples of these devices are cellphones, digital cameras, video cameras and digital televisions. However, raw videos present a huge amount of data, millions of bits, for their representation as the way they were captured. To store them in its primary form it would be necessary a huge amount of disk space and a huge bandwidth to allow the transmission of these data. The video compression becomes essential to make possible information storage and transmission. Motion Estimation is a technique used in the video coder that explores the temporal redundancy present in video sequences to reduce the amount of data necessary to represent the information. This work presents a hardware architecture of a motion estimation module for high resolution videos according to H.264/AVC standard. The H.264/AVC is the most advanced video coder standard, with several new features which allow it to achieve high compression rates. The architecture presented in this work was developed to provide a high data reuse. The data reuse schema adopted reduces the bandwidth required to execute motion estimation. The motion estimation is the task responsible for the largest share of the gains obtained with the H.264/AVC standard so this module is essential for final video coder performance. This work is included in Rede H.264 project which aims to develop Brazilian technology for Brazilian System of Digital Television

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The ferromagnetic materials play an important role in the development of various electronic devices and, have great importance insofar as they may determine the efficiency, cost and, size of the devices. For this reason, many scientific researches is currently focused on the study of materials at ever smaller scales, in order to understand and better control the properties of nanoscale systems, i.e. with dimensions of the order of nanometers, such as thin film ferromagnetic. In this work, we analyze the structural and magnetic properties and magnetoresistance effect in Permalloy-ferromagnetic thin films produced by magnetron sputtering. In this case, since the magnetoresistance effect dependent interfaces of thin films, this work is devoted to the study of the magnetoresistance in samples of Permalloy in nominal settings of: Ta[4nm]/Py[16nm]/Ta[4nm], Ta[4nm]/Py[16nm]/O2/Ta[4nm], Ta[4nm]/O2/Py[16nm]/Ta[4nm], Ta[4nm]/O2/Py[16n m]/O2/Ta[4nm], as made and subjected to heat treatment at temperatures of 160ºC, 360ºC e 460ºC, in order to verify the influence of the insertion of the oxygen in the layer structure of samples and thermal treatments carried out after production of the samples. Results are interpreted in terms of the structure of the samples, residual stresses stored during deposition, stresses induced by heat treatments and magnetic anisotropies

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The study of the elementary excitations such as photons, phonons, plasmons, polaritons, polarons, excitons and magnons, in crystalline solids and nanostructures systems are nowdays important active field for research works in solid state physics as well as in statistical physics. With this aim in mind, this work has two distinct parts. In the first one, we investigate the propagation of excitons polaritons in nanostructured periodic and quasiperiodic multilayers, from the description of the behavior for bulk and surface modes in their individual constituents. Through analytical, as well as computational numerical calculation, we obtain the spectra for both surface and bulk exciton-polaritons modes in the superstructures. Besides, we investigate also how the quasiperiodicity modifies the band structure related to the periodic case, stressing their amazing self-similar behavior leaving to their fractal/multifractal aspects. Afterwards, we present our results related to the so-called photonic crystals, the eletromagnetic analogue of the electronic crystalline structure. We consider periodic and quasiperiodic structures, in which one of their component presents a negative refractive index. This unusual optic characteristic is obtained when the electric permissivity and the magnetic permeability µ are both negatives for the same range of angular frequency ω of the incident wave. The given curves show how the transmission of the photon waves is modified, with a striking self-similar profile. Moreover, we analyze the modification of the usual Planck´s thermal spectrum when we use a quasiperiodic fotonic superlattice as a filter.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico

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Aborda o tratamento técnico informacional de discos sonoros na Biblioteca Especializada em Música Pe. Jaime Diniz, da Universidade Federal do Rio Grande do Norte. Caracteriza os discos sonoros enquanto suporte informacional. Relata as dificuldades encontradas no processo de tratamento da informação musical em materiais especiais. Objetiva estabelecer diretrizes para a análise, representação e organização do acervo de discos sonoros. Utiliza a pesquisa bibliográfica em fontes impressas e eletrônicas para o suporte teórico, tendo como metodologia o estudo de caso. Conclui que as regras e padrões para o tratamento técnico da informação no campo da Biblioteconomia podem sofrer adaptações para melhor representar o conteúdo musical dos discos sonoros, considerando a necessidade do profissional da informação em aperfeiçoar seus conhecimentos em música.

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This research aims at studying the use of greeting cards, here understood as a literacy practice widely used in American society of the United States. In American culture, these cards become sources of information and memory about people‟s cycles of life, their experiences and their bonds of sociability enabled by means of the senses that the image and the word comprise. The main purpose of this work is to describe how this literacy practice occurs in American society. Theoretically, this research is based on studies of literacy (BARTON, HAMILTON, 1998; BAYHAM, 1995; HAMILTON, 2000; STREET, 1981, 1984, 1985, 1993, 2003), the contributions of social semiotics, associated with systemic-functional grammar (HALLIDAY; HASAN 1978, 1985, HALLIDAY, 1994, HALLIDAY; MATTHIESSEN, 2004), and the grammar of visual design (KRESS; LEITE-GARCIA, VAN LEEUWEN, 1997, 2004, 2006; KRESS; MATTHIESSEN, 2004). Methodologically, it is a study that falls within the qualitative paradigm of interpretative character, which adopts ethnographic tools in data generation. From this perspective, it makes use of “looking and asking” techniques (ERICKSON, 1986, p. 119), complemented by the technique of "registering", proposed by Paz (2008). The corpus comprises 104 printed cards, provided by users of this cultural artifact, from which we selected 24, and 11 e-cards, extracted from the internet, as well as verbalizations obtained by applying a questionnaire prepared with open questions asked in order to gather information about the perceptions and actions of these cards users with respect to this literacy practice. Data analysis reveals cultural, economic and social aspects of this practice and the belief that literacy practice of using printed greeting cards, despite the existence of virtual alternatives, is still very fruitful in American society. The study also allows users to comprehend that the cardholders position themselves and construct identities that are expressed in verbal and visual interaction in order to achieve the desired effect. As a result, it is understood that greeting cards are not unintentional, but loaded with ideology and power relations, among other aspects that are constitutive of them.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES

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The main objective of the present work is to contribute to the development of the coordination chemistry of macromolecules such as resorcinarene with the synthesis and characterization of new copper complexes with chloride, vanillin and resorcinarene binders, all coordinated to phenanthroline, a biologically active molecule with important properties in biological systems. The complex [(Cu(phen))4(resvan)], was synthesized from the direct reaction of the metals with resorcinarene and generates several possibilities for coordination, which hinders its characterization. Therefore, in order to limit the coordination sites of the ligand, the complex [(Cu(phen))4(resvan)]Cl4 was formed from a new synthetic methodology. The complex cis-[Cu(phen)Cl2], cis-[Cu(phen)(van)]Cl, [(Cu(phen))4(resvan)] and [(Cu(phen))4(resvan)]Cl4 were characterized by spectroscopic techniques such as IR, UV-vis and EPR. By using infrared it has been possible to demonstrate the presence of the phenanthroline ligand in the synthesized complexes, and vanillin in the complex cis- [Cu(phen)(van)]Cl and resvan ligand in the complex [(Cu(phen))4(resvan)], besides this indicating the formation of resorcinarene in the complex [(Cu(phen))4(resvan)]Cl4. The electronic spectra of these coordination compounds indicated the presence of the phenanthroline ligand, by its intense bands in the ultraviolet region. For the complex cis- [Cu(phen)(van)]Cl it still indicated the presence of the ligand vanillin based on intraligand bands of vanillin and charge transfer, LMCT. Furthermore, the spectra showed d-d bands, confirming the formation of metal compounds. The amount of copper atoms present in the complex [(Cu(phen))4(resvan)]Cl4 was estimated from a comparative analysis of the absorbances of solutions of the same concentration of [(Cu(phen))4(resvan)]Cl4 and cis- [Cu(phen)(van)]Cl, which indicates that these compounds have copper atoms in the ratio 4:1. The EPR spectra of the complex cis-[Cu(phen)Cl2], cis-[Cu(phen)(van)]Cl and [(Cu(phen))4(resvan)]Cl4 showed axial profiles, while the complex [(Cu(phen))4(resvan)] showed of axial and rhombic profiles, indicating a change in the symmetry of the Cu (II) to this complex environment. The binders vanillin and resvan underwent biological assays with satisfactory results, both exhibited antioxidant activity and low toxicity, as well vanillin present antitoxoplásmico character.

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The present work aimed first, the theoretical study of tetrahedral intermediate stability formed from carbonyl addition reactions using the second (MP2) and third (MP3) order Møller–Plesset perturbation theory. Linear correlations between electronic energy difference of reactions with Wiberg Indexes and C-O bond lengths were obtained, and was observed that the stability of adducts formed depends directly of electronic density involved between these atoms. The knowing of electronic parameters of these structures has an important hole due to the large use on reactions that in his course forms this tetrahedral intermediate. Employing the ONIOM (B3LYP:AMBER) methodology, was evaluated the stereoselectivity of a enzymatic reaction between CAL B enzyme and a long chain ester. In this study, were obtained the electronic energies of ground state and intermediate state of transesterification rate-determing step from two possible proquirals faces Re and Si. The objective was study the enantioselectivity of CAL B and rationalizes it using quantum theory of atoms in molecules (QTAIM). A theoretical study employing inorganic compounds was performed using ab initio CBS-QB3 method aiming to find a link between thermodynamic and equilibrium involving acids and bases. The results observed showed an excellent relationship between difference in Gibbs free energy, ΔG of acid dissociation reaction and ΔG of hydrolysis reaction of the corresponding conjugate base. It was also observed, a relationship between ΔG of hydrolysis reaction of conjugate acids and their corresponding atomic radius showing that stability plays an important role in hydrolysis reactions. The importance of solvation in acid/base behavior when compared to theoretical and experimental ΔG´s also was evaluated.

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A major and growing problems faced by modern society is the high production of waste and related effects they produce, such as environmental degradation and pollution of various ecosystems, with direct effects on quality of life. The thermal treatment technologies have been widely used in the treatment of these wastes and thermal plasma is gaining importance in processing blanketing. This work is focused on developing an optimized system of supervision and control applied to a processing plant and petrochemical waste effluents using thermal plasma. The system is basically composed of a inductive plasma torch reactors washing system / exhaust gases and RF power used to generate plasma. The process of supervision and control of the plant is of paramount importance in the development of the ultimate goal. For this reason, various subsidies were created in the search for greater efficiency in the process, generating events, graphics / distribution and storage of data for each subsystem of the plant, process execution, control and 3D visualization of each subsystem of the plant between others. A communication platform between the virtual 3D plant architecture and a real control structure (hardware) was created. The goal is to use the concepts of mixed reality and develop strategies for different types of controls that allow manipulating 3D plant without restrictions and schedules, optimize the actual process. Studies have shown that one of the best ways to implement the control of generation inductively coupled plasma techniques is to use intelligent control, both for their efficiency in the results is low for its implementation, without requiring a specific model. The control strategy using Fuzzy Logic (Fuzzy-PI) was developed and implemented, and the results showed satisfactory condition on response time and viability

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The goal set for this work was to synthesize and to characterize new iron and copper complexes with the Schiff base 3-MeOsalen and ligands of biological relevance, whose formulas are [Fe(3-MeOsalen)NO2], [Fe(3-MeOsalen)(etil2-dtc)], [Fe(3-MeOsalen)NO] and Na[Cu(3-MeOsalen)NO2]. The compounds were characterized by vibrational spectroscopy in the infrared region (IV) and Electronic spectroscopy in the ultraviolet and visible region (Uv-Vis). From the analysis of infrared spectra, they proved to formation of precursor complexes, as evidenced by changes in the vibrationals frequencies ν(C=N) e ν(C-O) and the emergence of vibrationals modes metal-oxygen and metal-nitrogen. For nitro complexes of iron and copper were observed ν(NO2)ass around 1300 cm-1 e ν(NO2)sim in 1271 cm-1 , indicating that the coordination is done via the nitrogen atom. The complex spectrum [Fe(3-MeOsalen)(etil2-dtc)] exhibited two bands, the ν(C-NR2) in 1508 cm-1 e ν(C-S) in 997 cm-1 , the relevant vibrational modes of coordinating ligand in the bidentate form. For the complex [Fe(3-MeOsalen)NO] was observed a new intense band in 1670 cm-1 related to the ν(NO). With the electronic spectra, the formation of complexes was evidenced by shifts of bands intraligands transitions and the emergence of new bands such as LMCT (p Cl-  d* Fe3+) in [Fe(3-MeOsalen)Cl] and the d-d in [Cu(3-MeOsalen)H2O]. As for the [Fe(3-MeOsalen)NO2] has highlighted the absence of LMCT band present in the precursor complex as for the [Cu(3-MeOsalen)NO2] found that the displacement of the band hipsocrômico d-d on 28 nm. The electronic spectrum of [Fe(3-MeOsalen)(etil2-dtc)] presented LMCT band shifts and changes in intraligantes transitions. With regard to [Fe(3-MeOsalen)NO], revealed a more energetic transitions intraligands regions from the strong character π receiver NO and MLCT band of transition dπFe(II)π*(NO).

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Conselho Nacional de Desenvolvimento Científico e Tecnológico - CNPq

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The need to preserve the environment has led to the search for new materials for efficient disposal of chemical compounds that alter the stability of our natural resources. Among these resources, stands in first place the water, as a precious commodity and scarce, leading to the proper use and reuse. As a result, the World Health Organization has established maximum permissible values in drinking water, such as: 50 mg/L, 0, 1 mg/L and 0, 5 mg/L to at-3, at-2, NH 4, respectively. For these reasons, assesses the implementation of new materials and water treatment processes aiming at the removal of these compounds, such as alumina, in the form of powder or as a support for a catalytic system using inorganic membranes capable of supporting more severe conditions of temperature and pressure by opening new possibilities for applications of membrane reactors; and also for electrochemical treatments with doped diamond bobo electrodes (BDD) as anode and copper as cathode. For such purpose, was conducted the study of adsorption of nitrate in different times to assess the time required to achieve equilibrium by employing three commercial alumina called: acidic, basic and neutral alumina, with subsequent treatment only in the acidic alumina impregnating metals (PdCu/Al2O3) for the catalytic reaction. The materials were previously characterized by XRD, SEM techniques and ABET. Aluminas presented a considerable adsortive capacity of nitrate in the first thirty minutes, equivalent to 50% of removal reaching equilibrium in that time. After treatment, using alumina as catalyst for the reaction in batch reactor (Pd-Cu/Al2O3), the results were more favourable, totalling 64% reduction of ion NO3-at the end of three hours. On the other hand, the results for the catalytic reaction using the catalytic support Pd-Cu/TiO2 in membrane reactor proved to be low. -if, in this way, improve the conditions of catalytic system to optimize the process. Already, for the electrochemical tests using DDB1 electrodes as anode, and Cu, as cathode, there was a fairly significant nitrate reduction, approximately 80% of ion removal during three hours and cost viable applications.

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The detection of emerging interest microcontaminants in environmental samples of surface water, groundwater, drinking water, wastewater and effluents from water and sewage treatment plants (WTP and STP), in many countries, suggests these pollutants are widespread in the environment, mainly in urban areas. This is a reason for great concern, since many of these compounds are potentially harmful for humans other living beings, and they are not efficiently removed in the majority of WTP and STP, which is exacerbated by precariousness of water supply and sanitation services. In Natal, like other Brazilian cities, the sewage system serves only part of the urban area (about 30%), so that the rest of the wastewater is infiltrated in the sandy soil of the region in cesspool-dry well systems. This has resulted in contamination of groundwater in the area (sand-dune barrier aquifer, which supplies more than 50% of the city population), which has been observed by the increase in nitrate concentration in supply wells. The vulnerability of the sanddune barrier aquifer, combined with reports of the presence of emerging interest microcontaminants in Brazil and worldwide, led to this research, which investigated the occurrence of fifteen microcontaminants in Natal groundwater and sewage. Samples were collected at five wells used for water supply, the raw sewage and the effluents from biological reactors from STP (UASB and activated sludge reactors). Two samples of each sample were taken, with one week apart between the samples. To determine the contaminants, extraction of aquifer water, and raw and treated sewage samples were performed, through the technique of using SPE Strata X cartridge (Phenomenex®) to the aquifer water, and Strata SAX and Strata X (Phenomenex® ) for samples of raw and treated sewage. Subsequently the extracts were analyzed using GC-MS technique. Much of the analyzed microcontaminants were detected in groundwater and sewage. The concentrations in groundwater are generally lower than those found in the sewers. Some of the compounds (estrone, estradiol, bisphenol A, caffeine, diclofenac, naproxen, paracetamol and ibuprofen) are partially removed at STP.

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Composite NiO-C0.9Gd0.1O1.95 (NiO-GDC), one of the materials most used for the manufacture of anodes of Cells Solid Oxide Fuel (SOFC) currently, were obtained by a chemical route which consists in mixing the precursor solution of NiO and CGO phases obtained previously by the Pechini method. The nanopowders as-obtained were characterized by thermal analysis techniques (thermogravimetry and Differential Scanning Calorimetry) and calcined materials were evaluated by X-ray diffraction (XRD). Samples sintered between 1400 and 1500 ° C for 4 h were characterized by Archimedes method. The effects of the composition on the microstructure and electrical properties (conductivity and activation energy) of the composites sintered at 1500 ° C were investigated by electron microscopy and impedance spectroscopy (between 300 and 650 ° C in air). The refinement of the XRD data indicated that the powders are ultrafine and the crystallite size of the CGO phase decreases with increasing content of NiO. Similarly, the crystallite of the NiO phase tends to decrease with increasing concentration of CGO, especially above 50 wt % CGO. Analysis by Archimedes shows a variation in relative density due to the NiO content. Densities above 95% were obtained in samples containing from 50 wt % NiO and sintered between 1450 and 1500 °C. The results of microscopy and impedance spectroscopy indicate that from 30-40 wt.% NiO there is an increase in the number of contacts NiO - NiO, activating the electronic conduction mechanism which governs the process of conducting at low temperatures (300 - 500 °C). On the other hand, with increasing the measuring temperature the mobility of oxygen vacancies becomes larger than that of the electronic holes of NiO, as a result, the high temperature conductivity (500-650 ° C) in composites containing up to 30-40 wt.% of NiO is lower than that of CGO. Variations in activation energy confirm change of conduction mechanism with the increase of the NiO content. The composite containing 50 wt. % of each phase shows conductivity of 19 mS/cm at 650 °C (slightly higher than 13 mS/cm found for CGO) and activation energy of 0.49 eV.