895 resultados para Agregados de antenas


Relevância:

10.00% 10.00%

Publicador:

Resumo:

In Natal/RN, 68% of the population uses some kind of individual system for their domestic sewers treatment, being that the most used it is septic tank, followed by sumidouro. Every treatment system of sewers, usually used, generates a by-product denominated sludge. That residue presents some components, in its constitution, undesirable under the environmental and sanitary point of view. In such case, to assure that the system treatment has satisfactory results, it is necessary to do the adjusted disposition of the sludge sewage. Several countries are looking for technical alternatives for the use and disposition of residues. Under technical and environmental conditions appropriate, these materials can be used, decreasing the consumption of the natural resources and the treatment need, storage or elimination of the wastes, what decrease the risks created. Some of the alternatives of recycling of the sludge sewage are: the application in the agriculture, in the production of energy and as raw material in the civil construction. This study evaluated asphalt mixtures behavior that partially substituted conventional aggregates by septic tank sludge. The septic tank sludge gave origin to two raw materials called raw sludge and sludge ash. The raw sludge was put as a small aggregate and the sludge ash as filler. In the first experiment it was made a comparison between the mixture with conventional aggregates and the mixtures that replaced sand by raw sludge in the proportions from 5% to 40%. In the second experiment, it was made comparison between mixtures with 1%, 2% and 3% of sludge ash and cement. The stages developed along the study were: physical characterization of the conventional materials; physical, chemistry, thermal, mineralogical characterizations and analysis of environmental risk of the raw sludge; physical characterization and analysis of environmental risk of the sludge ash; analysis of the mixtures performance through its volumetric and mechanical characteristics; forecast of the mixtures susceptibility in the moisture presence. For the grain size composition used and with the percentage asphalt adopted, the mixtures with up to 7,5% of raw sludge in his composition attend to the National Department of Transports Infrastructure (DNIT) specifications. However, in agreement with the mixtures susceptibility in the moisture presence, the mixtures with addition of raw sludge don't present satisfactory acting. In such case, they could be used in arid and semi-arid areas. The raw sludge application in mixtures increased their voids volume and their stability. However, it damaged mixtures adhesiveness. Mixtures with sludge ash and with cement presented similar behavior. However, mixtures with sludge ash presented a better performance than mixtures with cement as for their stability and their tensile strength ratio. The mixture with 1% of sludge ash is better. The wastes studied don't represent environmental risk

Relevância:

10.00% 10.00%

Publicador:

Resumo:

A mistura de tensoativos com água, em determinadas proporções, na ausência ou na presença de substâncias lipofílicas pode formar diferentes tipos de agregados, entre os quais agregados polimorfos representados pelas microemulsões (ME) e mesofases liotrópicas - os cristais líquidos (LC), que estão intimamente ligados com a proporção e a natureza dos componentes da mistura. Nesse trabalho, foi discutido o papel desses sistemas na incorporação de fármacos com diferentes propriedades físico-químicas, influenciando fortemente a liberação, assim como a biodisponibilidade dos fármacos. Aspectos sobre a formação e a caracterização de microemulsões e cristais líquidos também foram discutidos. A análise da literatura indicou que, dependendo da polaridade do fármaco, o efeito da ME ou LC pode ser usado para otimizar o efeito terapêutico por meio do controle da velocidade ou do mecanismo de liberação do fármaco.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The use of habitat is an important part of a species biology. One resource of great importance for the survivor and reproduction of an individual is the food resource. Thus, the social interactions an animal has during the feeding activities are of extremely importance within its behavioral aspects, which represents the part of an organism trough which it interacts with the environment, adapting to changes and variations. Herons are known to form feeding aggregations of even more than thousands of individuals, in which social components of foraging have been identified and studied for several species. More profound studies of these aspects are yet to poor for the Little Blue Heron, Egretta caerulea. Therefore, the aim of this study was to describe the social behavior (display postures, vocalizations and co-specific interactions) and the territoriality of the specie during the feeding period in an area of mud bank in the estuarine system of Cananéia, south coast of São Paulo state, Brazil. The defense of a fixed and exclusive area, closest to the mangrove, trough expulsion was observed; some thing that have not yet been registered with concrete data for the specie. Higher capture and success rates, and lower investment rates (steps/min and stabs/min) were registered for individuals foraging in areas corresponding to the defended territory. This could be one of possible reasons for the establishment of territories in the area. Four display postures were registered for the specie, two of then new in the literature, which are used in the interactions between individuals; one vocalization, that apparently is important in the social context of foraging for the specie and, possibly, has a function of advertising and proclaiming the dominance position of the territorial individual within the group. A territorial individual uses three behaviors, of the ones described: expulsion, vocalization and encounter (agonistic encounter between individuals, without physical aggression). Of these, the expulsion is apparently used in the actual defense, actively; while the other two behaviors are used in a more passive way, in the maintenance of the dominance position of the individual, helping it in the defense of its territory in a less direct manner. Therefore, with the results presented in here, new components of the social utilization of the feeding resource for the Little Blue Heron were identified, incorporating aspects of the territorial behavior for a future understanding of its possible adaptive significance. And it also reinforces the importance of the social interactions of herons foraging in great aggregations, in areas ecologically important

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Modified polyacrylamides with ≅ 0.2 mol % of N,N-dihexylacrylamide and hydrolysis degree from 0 to 25 % were synthesized by micellar copolymerization. The hydrophobic monomer was obtained by the reaction between acryloyl chloride and N,Ndihexylamine and characterized by infrared (IR) and proton nuclear magnetic resonance (1H NMR) spectroscopy. The polymer molecular structures were determined through 1H and 13C NMR spectroscopy and the polymers were studied in dilute and semi-dilute regimes by viscometry, rheometry, static light scattering and photon correlation spectroscopy, at the temperature range from 25 to 55 ºC. The data obtained by viscometry showed that the intrinsic viscosity from the hydrolyzed polymers is larger than the precursor polymers at the same ionic strength. The comparison between the charged polymers showed that the polymer with higher hydrolysis degree has a more compact structure in formation water (AFS). The increase of temperature led to an enhanced reduced viscosity to the polymers in Milli-Q water (AMQ), although, in brine, only the unhydrolyzed polymer had an increase in the reduced viscosity with the temperature, and the hydrolyzed derivatives had a decrease in the reduced viscosity. The static light scattering (SLS) analyses in salt solutions evidenced a decrease of weight-average molecular weight (⎯Mw) with the increase of the hydrolysis degree, due to the reduction of the thermodynamic interactions between polymer and solvent, which was evidenced by the decrease of the second virial coefficient (A2). The polymers showed more than one relaxation mode in solution, when analyzed by photon correlation spectroscopy, and these modes were attributed to isolated coils and aggregates of several sizes. The aggregation behavior depended strongly on the ionic strength, and also on the temperature, although in a lower extension. The polymers showed large aggregates in all studied conditions, however, their solutions did not displayed a good increase in water viscosity to be used in enhanced oil recovery (EOR) processes

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Chitosan is a biopolymer derived from the shells of crustaceans, biodegradable, inexpensive and renewable with important physical and chemical properties. Moreover, the different modifications possible in its chemical structure generate new properties, making it an attractive polysaccharide owing to its range of potential applications. Polymers have been used in oil production operations. However, growing concern over environmental constraints has prompted oil industry to search for environmentally sustainable materials. As such, this study sought to obtain chitosan derivatives grafted with hydrophilic (poly(ethylene glycol), mPEG) and/or hydrophobic groups (n-dodecyl) via a simple (one-pot) method and evaluate their physicochemical properties as a function of varying pH using rheology, small-angle Xray scattering (SAXS), dynamic light scattering (DLS) and zeta potential. The chitosan derivatives were prepared using reductive alkylation under mild reaction conditions and the chemical structure of the polymers was characterized by nuclear magnetic resonance (1H NMR) and CHN elemental analysis. Considering a constant mPEG/Chitosan molar ratio on modification of chitosan, the solubility of the polymer across a wide pH range (acidic, neutral and basic) could only be improved when some of the amino groups were submitted to reacetylation using the one-pot method. Under these conditions, solubility is maintained even with the simultaneous insertion of n-dodecyl. On the other hand, the solubility of derivatives obtained only through mPEG incorporation using the traditional methodology, or with the ndodecyl group, was similar to that of its precursor. The hydrophilic group promoted decreased viscosity of the polymer solutions at 10 g/L in acid medium. However, at basic pH, both viscosity and thermal stability increased, as well as exhibited a pronounced pseudoplastic behavior, suggesting strong intermolecular associations in the alkaline medium. The SAXS results showed a polyelectrolyte behavior with the decrease in pH for the polymer systems. DLS analyses revealed that although the dilute polymer solutions at 1 g/L and pH 3 exhibited a high density of protonated amino groups along the polymer chain, the high degree of charge contributed significantly to aggregation, promoting increased particle size with the decrease in pH. Furthermore, the hydrophobic group also contributed to increasing the size of aggregates in solution at pH 3, whereas the hydrophilic group helped reduce their size across the entire pH range. Nevertheless, the nature of aggregation was dependent on the pH of the medium. Zeta potential results indicated that its values do not depend solely on the surface charge of the particle, but are also dependent on the net charge of the medium. In this study, water soluble associative polymers exhibit properties that can be of great interest in the petroleum industry

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Helicobacter pylori is the main cause of gastritis, gastroduodenal ulcer disease and gastric cancer. The most recommended treatment for eradication of this bacteria often leads to side effects and patient poor compliance, which induce treatment failure. Magnetic drug targeting is a very efficient method that overcomes these drawbacks through association of the drug with a magnetic compound. Such approach may allow such systems to be placed slowed down to a specific target area by an external magnetic field. This work reports a study of the synthesis and characterization of polymeric magnetic particles loaded with the currently used antimicrobial agents for the treatment of Helicobacter pylori infections, aiming the production of magnetic drug delivery system by oral route. Optical microscopy, scanning electron microscopy, transmission electron microscopy, x-ray powder diffraction, nitrogen adsorption/desorption isotherms and vibrating sample magnetometry revealed that the magnetite particles, produced by the co-precipitation method, consisted of a large number of aggregated nanometer-size crystallites (about 6 nm), creating superparamagnetic micrometer with high magnetic susceptibility particles with an average diameter of 6.8 ± 0.2 μm. Also, the polymeric magnetic particles produced by spray drying had a core-shell structure based on magnetite microparticles, amoxicillin and clarithromycin and coated with Eudragit® S100. The system presented an average diameter of 14.2 ± 0.2 μm. The amount of magnetite present in the system may be tailored by suitably controlling the suspension used to feed the spray dryer. In the present work it was 2.9% (w/w). The magnetic system produced may prove to be very promising for eradication of Helicobacter pylori infections

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Peng was the first to work with the Technical DFA (Detrended Fluctuation Analysis), a tool capable of detecting auto-long-range correlation in time series with non-stationary. In this study, the technique of DFA is used to obtain the Hurst exponent (H) profile of the electric neutron porosity of the 52 oil wells in Namorado Field, located in the Campos Basin -Brazil. The purpose is to know if the Hurst exponent can be used to characterize spatial distribution of wells. Thus, we verify that the wells that have close values of H are spatially close together. In this work we used the method of hierarchical clustering and non-hierarchical clustering method (the k-mean method). Then compare the two methods to see which of the two provides the best result. From this, was the parameter � (index neighborhood) which checks whether a data set generated by the k- average method, or at random, so in fact spatial patterns. High values of � indicate that the data are aggregated, while low values of � indicate that the data are scattered (no spatial correlation). Using the Monte Carlo method showed that combined data show a random distribution of � below the empirical value. So the empirical evidence of H obtained from 52 wells are grouped geographically. By passing the data of standard curves with the results obtained by the k-mean, confirming that it is effective to correlate well in spatial distribution

Relevância:

10.00% 10.00%

Publicador:

Resumo:

As miopatias em equinos são classificadas de acordo com aspectos clínicos, morfológicos e moleculares, em três grandes grupos: não associadas ao exercício, associadas ao exercício e devido alteração da condução elétrica do sarcolema. Apesar dos avanços no diagnóstico, a literatura ainda relata surtos de miopatia em equinos sem etiologia esclarecida em diversos países. O objetivo desse estudo foi descrever as alterações histológicas e histoquímicas de biópsias musculares de equinos acometidos por miopatia. Sete equinos da raça Quarto de Milha, com 18-24 meses de idade, apresentaram sinais clínicos de miopatia. Dentre esses animais, cinco apresentaram sinais subagudos leves a moderados e dois apresentaram sinais hiperagudos severos e decúbito lateral. Foram realizadas biópsias musculares utilizando a técnica percutânea, por agulha tipo Bergström, no músculo glúteo médio em todos os animais acometidos. As amostras foram processadas por meio de técnicas histológicas (HE, Tricrômio de Gomori modificado) e histoquímicas (PAS, NADH, ATPase). Nos quadros clínicos mais leves, a principal alteração encontrada foi a presença de fibras vermelhas rajadas do tipo I e IIA, que estão associadas às alterações do metabolismo oxidativo e das funções mitocondriais, como ocorrem nas miopatias mitocondriais. Também foram observadas fibras atróficas do tipo I e IIA, além da presença de agregados subsarcolemais. Nos quadros mais severos o tecido muscular apresentou infiltrado inflamatório, aumento de colágeno, fagocitose, necrose, calcificação e regeneração muscular. Diante dos achados morfológicos, da resposta à terapia com vitamina E e Se e da baixa mortalidade quando comparado aos relatos de miopatia atípica, conclui-se que esse surto foi desencadeado por lesões mitocondriais, caracterizadas pelas fibras musculares vermelhas rajadas, possivelmente devido uma quebra da homeostase de vitamina E e Se, sendo compatível com o diagnóstico de miopatia nutricional.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The great interest observed in wireless communication systems has required the development of new configurations of microstrip antennas, because they are easily built and integrated to other microwave circuit components, which is suitable for the construction and development of planar antenna arrays and microwave integrated circuits. This work presents a new configuration of tapered microstrip antenna, which is obtained by impressing U-slots on the conducting patch combined with a transmission line matching circuit that uses an inset length. It is shown that the use of U-slots in the microstrip antenna conducting patch excites new resonating modes, that gives a multiband characteristic for the slotted microstrip antenna, that is suitable for applications in communication systems that operates several frequencies simultaneously. Up to this date, the works reported in the literature deals with the use of Uslotted microstrip rectangular antennas fed by a coaxial probe. The properties of a linear array of microstrip patch tapered antennas are also investigated. The main parameters of the U slotted tapered microstrip antennas are investigated for different sizes and locations of the slots impressed on the conducting patch. The analysis of the proposed antenna is performed by using the resonant cavity and equivalent transmission line methods, in combination with a parametric study, that is conducted by the use of the Ansoft Designer, a commercial computer aided microwave software well known by its accuracy and efficiency. The mentioned methods are used to evaluate the effect in the antennas parameters, like resonant frequency and return loss, produced by variations of the antenna structural parameters, accomplished separately or simultaneously. An experimental investigation is also developed, that consists of the design, construction and measurement of several U slotted microstrip antenna prototypes. Finally, theoretical and simulated results are presented that are in agreement with the measured ones. These results are related to the resonating modes identification and to the determination of the main characteristics of the investigated antennas, such as resonant frequency, return loss, and radiation pattern

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The use of Multiple Input Multiple Output (MIMO) systems has permitted the recent evolution of wireless communication standards. The Spatial Multiplexing MIMO technique, in particular, provides a linear gain at the transmission capacity with the minimum between the numbers of transmit and receive antennas. To obtain a near capacity performance in SM-MIMO systems a soft decision Maximum A Posteriori Probability MIMO detector is necessary. However, such detector is too complex for practical solutions. Hence, the goal of a MIMO detector algorithm aimed for implementation is to get a good approximation of the ideal detector while keeping an acceptable complexity. Moreover, the algorithm needs to be mapped to a VLSI architecture with small area and high data rate. Since Spatial Multiplexing is a recent technique, it is argued that there is still much room for development of related algorithms and architectures. Therefore, this thesis focused on the study of sub optimum algorithms and VLSI architectures for broadband MIMO detector with soft decision. As a result, novel algorithms have been developed starting from proposals of optimizations for already established algorithms. Based on these results, new MIMO detector architectures with configurable modulation and competitive area, performance and data rate parameters are here proposed. The developed algorithms have been extensively simulated and the architectures were synthesized so that the results can serve as a reference for other works in the area

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Difusive processes are extremely common in Nature. Many complex systems, such as microbial colonies, colloidal aggregates, difusion of fluids, and migration of populations, involve a large number of similar units that form fractal structures. A new model of difusive agregation was proposed recently by Filoche and Sapoval [68]. Based on their work, we develop a model called Difusion with Aggregation and Spontaneous Reorganization . This model consists of a set of particles with excluded volume interactions, which perform random walks on a square lattice. Initially, the lattice is occupied with a density p = N/L2 of particles occupying distinct, randomly chosen positions. One of the particles is selected at random as the active particle. This particle executes a random walk until it visits a site occupied by another particle, j. When this happens, the active particle is rejected back to its previous position (neighboring particle j), and a new active particle is selected at random from the set of N particles. Following an initial transient, the system attains a stationary regime. In this work we study the stationary regime, focusing on scaling properties of the particle distribution, as characterized by the pair correlation function ø(r). The latter is calculated by averaging over a long sequence of configurations generated in the stationary regime, using systems of size 50, 75, 100, 150, . . . , 700. The pair correlation function exhibits distinct behaviors in three diferent density ranges, which we term subcritical, critical, and supercritical. We show that in the subcritical regime, the particle distribution is characterized by a fractal dimension. We also analyze the decay of temporal correlations

Relevância:

10.00% 10.00%

Publicador:

Resumo:

This work shows a integrated study of modern analog to fluvial reservoirs of Açu Formation (Unit 3). The modern analog studied has been Assu River located in the same named city, Rio Grande do Norte State, Northeast of Brazil. It has been developed a new methodology to parameterizating the fluvial geological bodies by GPR profile (by central frequency antennas of 50, 100 and 200 MHz). The main parameters obtained were width and thickness. Still in the parameterization, orthophotomaps have been used to calculate the canal sinuosity and braided parameters of Assu River. These information are integrated in a database to supply input data in 3D geological models of fluvial reservoirs. It was made an architectural characterization of the deposit by trench description, GPR profile interpretation and natural expositions study to recognize and describe the facies and its associations, external and internal geometries, boundary surfaces and archtetural elements. Finally, a three-dimensional modeling has been built using all the acquired data already in association with real well data of a reservoir which Rio Assu is considered as analogous. Facies simulations have been used simple kriging (deterministic algorithm), SIS and Boolean (object-based, both stochastics). And, for modeling porosities have used the stochastic algorithm SGS

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Because the penetration depth of Ground Penetrating Radar (GPR) signals is very limited in high conductive soils, the usefullness of this method in tropical regions is not yet completly known. The main objective of this researh is to test the usefullness of the method in Brazil. Two typical problems where GPR has been used in Europe and North American were choosed for this test: the first one is to characterize the internal structures of a sand body and the second problem is the localization of old buried pipes lines. The first test was done near the city of São Bento do Norte, in the northern coast of Rio Grande do Norte state, NE Brazil. In this region, there is a sand dune that is migrating very fast in the direction of adjacent settling areas. To characterize the internal structure of the dune and its relationship to the prevailing wind direction, as a preliminary step to understand the dune migration, GPR profiles using the 400 MHz frequency were performed in E-W, N-S, NE-SW, and SE-NW directions over the sand dune intersecting at the top of the dune. The practical resolution of the GPR data is around 30 cm; this was sufficient to distinguish individual foresets inside the dune. After applying the elevation correction to the data, we identified that dips of bedding structures are smallest for the N-S profile, which is perpendicular to the dominant wind direction, largest for the E-W profile, and intermediate for the SW-NE and SE-NW profiles. Foresets in the E-W profile dip with angles varying from 2 to 6 degrees. In the E-W profile, the water table and a horizontal truncation interface separating two generations of dunes were identified, as well as an abrupt directional change in the foreset patterns associated to a lateral contact between two dune generations, the older one extending to the west. The used high frequency of 400 Mhz does not allow a penetration deep enough to map completely these internal contacts. The second test was done near Estreito, a small town near Carnaúbais city, also in Rio Grande do Norte state. In this locality, there are several old pipe lines buried in area covered by plantations where digging should be minimized. Several GPR profiles using the 400 and 200 MHz frequency were performed trying to intercept perpendicularly the possible pipe lines. Because of the high conductivity of the soil, the raw original data can hardly be use to identify the pipe lines. However, after an adequate processing over the 200 MHz profiles, six pipe lines were identified. As a global result of the tests, GPR can be very usefull if the conductivity of the ground is low or, in the case of medium conductivities of the soils, if adequate processing is performed

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The current work was developed on the dune systems of the Parque das Dunas and Barreira do Inferno. These places are located in the cities of Natal and Parnamirim (RN, Brazil), respectively. This project has the purpose of developing the deterministic model on a specific blowout at Parque das Dunas, based in the geophysical interpretations of the lines gotten with the Ground Penetration Radar and the planialtimetric acquisitions of the topographical surface of the land. Also analyses of the vulnerability/susceptibility of these dune systems had been done in relation to the human pressures. To develop its deterministic model, it is necessary to acquire inner and outer geometries of the cited blowout. In order to depict inner geometries underneath the surface are used the GPR observing the altimetric control for topographical correction of the GPR lines. As for the outer geometries, the geodesic GPS gives us the planialtimetric points (x, y and z points) with milimetric precision, resulting in high-resolution surfaces. Using interpolation methods of the planialtimetric points was possible create Digital Elevations Models (DEM´s) of these surfaces. As a result, 1,161.4 meters of GPR lines were acquired on the blowout at the Parque das Dunas and 3,735.27 meters on the blowout at the Barreira do Inferno. These lines had been acquired with a 200 MHz antenna, except the 7 and 8 lines, for which we had been used a 100 MHz antenna. The gotten data had been processed and interpreted, being possible to identify boundary surfaces of first, second and third order. The first order boundary surface is related with the contact of the rocks of the Barreiras Group with the aeolian deposits. These deposits had been divided in two groups (Group 1 and Group 2) which are related with the geometry of stratum and the dip of its stratifications. Group 1 presented stratum of sigmoidal and irregular geometries and involved bodies where the reflectors had presented dips that had varied of 20 to the 28 degrees for the Parque das Dunas blowout and of 22 to the 29 degrees for the Barreira do Inferno blowout. Usually, it was limited in the base for the first order surface and in the top for the second order surface. Group 2 presented stratum of trough, wedge or lens geometries, limited in the base for the second order vi surface, where the corresponding deposits had more shown smoothed reflectors or with dips of low angle. The Deterministic and Digital Elevation Models had been developed from the integration and interpretation of the 2D data with the GOCAD® program. In Digital Elevations Models it was possible to see, for the localities, corridor or trough-shaped blowouts. In Deterministic Model it was possible to see first and second order boundary surfaces. For the vulnerability/susceptibility of the dune systems it was applied the methodology proposal by Boderè al (1991); however the same one did not show adequate because it evaluates actual coastal dunes. Actual coastal dunes are dunes that are presented in balance with the current environmental conditions. Therefore, a new methodology was proposal which characterizes the supplying and activity sedimentary, as well as the human pressures. For the methodology developed in this work, both the localities had presented a good management. The Parque das Dunas was characterized as a relic dune system and the Barreira do Inferno was characterized as a palimpsestic dune system. Also two Thematic Maps had been elaborated for the environmental characterization of the studied dune systems, with software ArcGis 8.3, and its respective data bases