Bi anisotropia em antenas de microfita retangular e estruturas circulares modificadas

The microstrip antennas in your simplest form consist of a ground plane and a dielectric substrate which supports a conductive tape. As these antennas have some limitations, this work presents a study of anisotropic substrates, as well as some results in microstrip antennas with circular patch, aiming to overcome these limitations, especially in applications at 4G technology. These anisotropic substrates are those in which electrical permittivity and magnetic permeability are represented by tensors of second order. The study consists of a theoretical analysis of substrates and development of a mathematical formalism, the Transverse Transmission Line Method, aimed the application of these substrates in microstrip antennas. Among the substrates used in this study, there are the ferrimagnetic and metamaterials, in which some miniaturizations of the antennas are achieved. For antennas with circular patch, are considered arrays and modified ground planes in order to achieve improvement in parameters, in particular, gain and bandwidth. Several simulations have been made and antennas were constructed so that the measured values could be compared with the simulated values.

Materiais a base de estruturas carbonáceas para a remoção de ácidos húmicos em soluções aquosas através da adsorção e oxidação

O presente estudo aborda a utilização de carvão ativado comercial na remoção de ácidos húmicos em meio aquoso. O objetivo principal é desenvolver e caracterizar materiais carbonáceos visando aplicações de remoção de ácidos húmicos em meio aquoso por processos de adsorção e oxidação. Testes de remoção do poluente foram desenvolvidos com a utilização do carvão comercial, carvão modificado a partir de tratamentos ácidos e compósito confeccionado com a impregnação de ferro no carvão. Espumas de carbono com dispersões de carvão ativado e óxidos de ferro também foram desenvolvidas buscando aplicações de remoção do poluente através de processos eletroquímicos. Os resultados das caracterizações demonstraram ganho de área superficial a partir do tratamento ácido, a presença dispersa de ferro em todo carvão na forma de fase maghemita com a introdução do metal, e ganho de estabilidade eletroquímica na espuma, com a presença de dispersões de carvão ativados impregnados com ferro. O processo oxidativo Fenton, foto assistido por radiação UV, demonstrou maior eficiência para remoção do ácido húmico em água.

Fabricação e caracterização de um compósito hibrido com resíduo lignocelulósico

This work aims to manufacture and characterize a hybrid plastic composite with the matrix isophthalic polyester resin base and having as reinforcing glass fiber and the dry endocarp of coconut (Coco nucifera Linn) in the form of particles as filler. The composite was made industrially in Tecniplas Industry and Trade LTDA. in the form of plate, and was manufactured process made by the manual lamination (Hand Lay Up). From the plate they were prepared test specimens for testing density, water absorption, uniaxial traction in dry and wet states, and testing of bending, as well as studies on the behavior of the generated fractures, macroscopic and microscopic, in mechanical tests through. All tests were performed in order to find the most viable applications the hybrid composite manufactured. The tensile and bending tests were analyzed last tensile properties, elasticity and deformation module. After the studies, it is observed that the percentage moisture absorbed was 3.03%. The presence of moisture in the tensile test meant a decrease of 19.77% from last stand, and 5.26% in the elastic modulus. For bending tests gave an average value of 69.13 MPa flexural strength. The results show the application of hybrid composite studied in lightweight structures, indoors, which require low / medium performance traction demands, and which involve flexural requests.

Utilização do titâneo na confecção de estruturas metálicas em prótese parcial removível

Due to properties such as excellent biocompatibility, high resistance to corrosion and low specific weight, titanium has been considered a material of great interest for Dentistry. It has been widely used in implants and orthognathic surgeries. Recently, titanium has been seen as a feasible alternative for the fabrication of removable partial denture frameworks, either in pure titanium (99.75%) or in titanium alloy forms (Ti-6Al-4V; Ti-6A1-7Nb). Based on a review of the literature, this work studied the use of titanium for the fabrication of removable partial denture frameworks, focusing on its advantages and disadvantages as well as its characteristics. It was concluded that the use of titanium is a convenient option for partially edentulous arches rehabilitation with quite satisfactory and promising clinical results. However, the need for highly-equipped laboratories increases the cost, preventing its large scale use.

Utilização do titâneo na confecção de estruturas metálicas em prótese parcial removível

Due to properties such as excellent biocompatibility, high resistance to corrosion and low specific weight, titanium has been considered a material of great interest for Dentistry. It has been widely used in implants and orthognathic surgeries. Recently, titanium has been seen as a feasible alternative for the fabrication of removable partial denture frameworks, either in pure titanium (99.75%) or in titanium alloy forms (Ti-6Al-4V; Ti-6A1-7Nb). Based on a review of the literature, this work studied the use of titanium for the fabrication of removable partial denture frameworks, focusing on its advantages and disadvantages as well as its characteristics. It was concluded that the use of titanium is a convenient option for partially edentulous arches rehabilitation with quite satisfactory and promising clinical results. However, the need for highly-equipped laboratories increases the cost, preventing its large scale use.

Controle ativo de vibração em estruturas inteligentes utilizando um controlador por modos deslizantes com compensação difusa

Smart structures and systems have the main purpose to mimic living organisms, which are essentially characterized by an autoregulatory behavior. Therefore, this kind of structure has adaptive characteristics with stimulus-response mechanisms. The term adaptive structure has been used to identify structural systems that are capable of changing their geometry or physical properties with the purpose of performing a specific task. In this work, a sliding mode controller with fuzzy inference is applied for active vibration control in an SMA two-bar truss. In order to obtain a simpler controller, a polynomial model is used in the control law, while a more sophisticated version, which presents close agreement with experimental data, is applied to describe the SMA behavior of the structural elements. This system has a rich dynamic response and can easily reach a chaotic behavior even at moderate loads and frequencies. Therefore, this approach has the advantage of not only obtaining a simpler control law, but also allows its robustness be evidenced. Numerical simulations are carried out in order to demonstrate the control system performance.

Controle ativo de vibração em estruturas inteligentes utilizando um controlador por modos deslizantes com compensação difusa

Smart structures and systems have the main purpose to mimic living organisms, which are essentially characterized by an autoregulatory behavior. Therefore, this kind of structure has adaptive characteristics with stimulus-response mechanisms. The term adaptive structure has been used to identify structural systems that are capable of changing their geometry or physical properties with the purpose of performing a specific task. In this work, a sliding mode controller with fuzzy inference is applied for active vibration control in an SMA two-bar truss. In order to obtain a simpler controller, a polynomial model is used in the control law, while a more sophisticated version, which presents close agreement with experimental data, is applied to describe the SMA behavior of the structural elements. This system has a rich dynamic response and can easily reach a chaotic behavior even at moderate loads and frequencies. Therefore, this approach has the advantage of not only obtaining a simpler control law, but also allows its robustness be evidenced. Numerical simulations are carried out in order to demonstrate the control system performance.

Efeitos da dieta hipoprotéica na formação e composição de estruturas dentárias: estudo experimental em ratos Wistar

Protein and caloric malnutrition has been considered one of the most concerned endemic diseases in Brazil and in the world. It has been known that depletion or reduction of proteins as far as meals are concerned can steer irreversible damages upon several organic systems. This study had as aim evaluate the effects the low-protein diet had over the formation and composition of the teeth components. 18 females and 6 males were used for the experiment. 12 from the 18 females had undertaken the low-protein diet (DH) for 03 weeks and the other 6, which remained, and those males had undertaken a controlled diet (DC) for the same period. All animals had the diets during their mating, pregnancy and lactation cycle. As soon as the offsprings had been born, 10 young males and females of each group faced a disease hood analysis to check the teeth germs of their lower fore teeth. The rest of the group had their lactation cycle normally 60 days. Then they were put to death and had their lower fore teeth removed both to be analyzed through a scanning electronic microscopy (SEM) of the structure alterations and to have their calcium checked by an atomic absorption of the phosphorus vanadate-molibdate method and by other minerals EDX method. The animals livers were removed to have their hepatic proteins analyzed as well. The histopatologic study showed that at first day of birth, all animals had their lower fore teeth come out. It was verified that 90% of the animals teeth were in an apposition and calcification period and it was possible to observe the dentin formation from 60% of the 90% already mentioned. Through the SEM method it could be realized that 90% of the animals of the DH group had their lower fore teeth easily broken and no definite shape. In this same group itself, it was also observed long micro fissures 369,66 nm ± 3,45 while the DC group had fissures of 174 nm ± 5,72. Now regarding the calcium and phosphorus concentration, it could be noticed that there was a great reduction of these components and other minerals in the DH group. Almost all minerals, except for the Cl and K, presented higher levels in the DC group enamel.The reduction of the protein input greatly influenced the offsprings´ weight and height. However the hepatic proteins had no important difference between the groups what can make one believe that those animals suffered from protein malnutrition of marasmic kind

Estruturas cerâmicas a base de zircônia e alumina utilizadas na confecção de infra - estruturas para coroas e pontes fixas

The continuous advances in ceramic systems for crowns and bridges infrastructure getting researchers and manufacturers looking for a material that has good mechanical properties and aesthetic. The purpose of this study was to verify in which composition and sintering temperature the ceramic system for infrastructure composed of alumina and zirconia would have the best mechanical properties. With this objective we made in UFRN laboratories 45 test bodies in the form of rectangular bars with the following dimensions: 30mm x 8mm x 3mm, where we separated by the sintering temperature: 1200°C, 1300ºC and 1400ºC, and by comp osition: 33% Zirconia + 67% Alumina; 50% Zirconia + 50% Alumina and 25% Zirconia + 75% Alumina, these test bodies were not infiltrated with glass. Also, were made nine test bodies by a technical from a laboratory with a commercial ceramic system: in the Ceram Zircônia (Vita - Zahnfabrik) with the following dimensions: 20mm x 10mm x 0.5mm, these test bodies following all recommendations of the manufacturer and were infiltrated with glass. Were realized optical and electronic microscopy analyses, hardness testing, resistance to bending in three points, porosity and bulk density. After analysis of the results we verified that with the increasing of sintering temperature, increased the value of resistance to bending, but with the same temperature there was no significant difference between the different compositions, samples made with the commercial ceramic that were infiltrated, presented a resistance to bending six times greater than the samples sintered to 1400°C and which have not been infiltra ted. There was no significant difference between the values of apparent porosity for the samples made in UFRN laboratories, but the samples of commercial ceramic obtained 0% in porosity apparent value. In tests of Rockwell Hardness there is an increase in the value of Hardness, with the increase of sintering temperature for the samples not infiltrated. Samples infiltrated showed similar values as the samples sintered in 1400°C. There was no significant difference between the values of apparent density among samples manufactured in UFRN laboratories and samples made with a commercial ceramic

Análise gráfica de estruturas porosas sobre a ótica da estereologia

In this work we developed a computer simulation program for physics porous structures based on programming language C + + using a Geforce 9600 GT with the PhysX chip, originally developed for video games. With this tool, the ability of physical interaction between simulated objects is enlarged, allowing to simulate a porous structure, for example, reservoir rocks and structures with high density. The initial procedure for developing the simulation is the construction of porous cubic structure consisting of spheres with a single size and with varying sizes. In addition, structures can also be simulated with various volume fractions. The results presented are divided into two parts: first, the ball shall be deemed as solid grains, ie the matrix phase represents the porosity, the second, the spheres are considered as pores. In this case the matrix phase represents the solid phase. The simulations in both cases are the same, but the simulated structures are intrinsically different. To validate the results presented by the program, simulations were performed by varying the amount of grain, the grain size distribution and void fraction in the structure. All results showed statistically reliable and consistent with those presented in the literature. The mean values and distributions of stereological parameters measured, such as intercept linear section of perimeter area, sectional area and mean free path are in agreement with the results obtained in the literature for the structures simulated. The results may help the understanding of real structures.

Simulação computacional de medidas estereológicas em estruturas de metal duro (WC-Co)

This work focuses on the creation and applications of a dynamic simulation software in order to study the hard metal structure (WC-Co). The technological ground used to increase the GPU hardware capacity was Geforce 9600 GT along with the PhysX chip created to make games more realistic. The software simulates the three-dimensional carbide structure to the shape of a cubic box where tungsten carbide (WC) are modeled as triangular prisms and truncated triangular prisms. The program was proven effective regarding checking testes, ranging from calculations of parameter measures such as the capacity to increase the number of particles simulated dynamically. It was possible to make an investigation of both the mean parameters and distributions stereological parameters used to characterize the carbide structure through cutting plans. Grounded on the cutting plans concerning the analyzed structures, we have investigated the linear intercepts, the intercepts to the area, and the perimeter section of the intercepted grains as well as the binder phase to the structure by calculating the mean value and distribution of the free path. As literature shows almost consensually that the distribution of the linear intercepts is lognormal, this suggests that the grain distribution is also lognormal. Thus, a routine was developed regarding the program which made possible a more detailed research on this issue. We have observed that it is possible, under certain values for the parameters which define the shape and size of the Prismatic grain to find out the distribution to the linear intercepts that approach the lognormal shape. Regarding a number of developed simulations, we have observed that the distribution curves of the linear and area intercepts as well as the perimeter section are consistent with studies on static computer simulation to these parameters.

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