Cinética de degradação do sistema resina epóxi/fibra de carbono

With the increasing demand for electricity, the retraining of transmission lines is necessary despite environmental restrictions and crossings in densely populated areas to build new transmission and distribution lines. Solution is reuse the existent cables, replacing the old conductor cables for new cables with higher capacity power transmission, and control of sag installed. The increasing demand for electrical power has increased the electric current on the wires and therefore, it must bear out temperatures of 150°C or more, without the risk of the increasing sag beyond the established limits. In the case of long crossings or densely populated areas, sag is due to high weight of the cable on clearance. The cable type determines the weight, sag, height and the towers dimensions, which are the items that most influence the investment of the transmission line. Hence, to reduce both cost of investment and maintenance of the line, the use of a lighter cable can reduce both number and the height of the towers, with financial return on short and long term. Therefore, in order to increase the amount of transmitted energy and reduce the number of built towers and sag, is recommended in the current work substitute the current core material (steel or aluminium) for alternatives alloys or new materials, in this case a composite, which has low density, elevated stiffness (elasticity module), thus apply the pultruded carbon fiber with epoxy resin as matrix systems and perform the study of the kinetics of degradation by thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA) and differential scanning calorimetry (DSC), according to their respective standards

Análise teórica e simulação computacional de um sistema de resfriamento líquido de processadores de computadores pessoais

This paper aims to study the thermal aspects involved in a liquid cooling system for processors, analyzing their competitiveness and efficiency across the fins and fan system usually used by personal computers, because electronic components become more potent and consequently current methods of cooling are becoming ineffective. The liquid cooling system and air cooling system have different heat transfer mechanisms that involve mainly convection and conduction heat transfer modes, and, furthermore, requires an analysis of fluid dynamics, which can evaluate the losses involved in the closed system, consisting in an exchanger heat pipe and water blocks in liquid cooling system or heat sink and turbo-axial fan in the air cooling system

Colheita de energia usando dispositivos baseados em materiais piezoelétrico

Recently, research on energy harvesting has increased substantially. Many researchers have concentrated their efforts to find the best configuration for these systems and to optimize their output power. In the process of energy harvesting, the electric energy is obtained by converting mechanics energy created by an environment vibration source by a transducer, for example, a thin piezoceramic film. That vibration source is, for example, a beam suffering some mechanic force able to generate a vibration in it, an oscillating beam is the best properly used example. Different mechanisms of electromechanical coupling have been developed to harvesting devices, and a particular interest has been given to the use of models that transform the mechanical vibration into electrical current using a piezoelectric element. In this paper we propose a model to energy harvesting from vibrations, from an oscillating beam, including non-linearities in the piezoelectric coupling and a non-ideal excitation in the material. From this model, it was developed a system to obtain some results about the harvested power by the material. It was demonstrated that the power captured was influenced by the effect of the nonlinearities of the piezoelectric coupling, modifying the system dynamic behavior

Estudo teórico da contribuição do espalhamento nuclear não elástico na trajetória de prótons de energias entre 50 e 250 MeV em materiais de interesse em radiologia: aplicação em tomografia com prótons

The goal of this work is to study the process of interaction of protons with matter through Monte Carlo simulation. For this purpose, it was employed the SRIM program (Stopping and Range of Ions in Matter ) and MCNPX (Monte Carlo N-Particle eXtended) v2.50. This work is going to support the development of a tomography system with protons. It was studied the interaction of proton with the follow materials: Polimethyl Mehacralate (PMMA), MS20 Tissue Substitute and water. This work employed energies in range of 50 MeV and 250 MeV, that is the range of clinical interest. The energy loss of proton after cross a material layer, the decreasing of its intensity, the angular and lateral de ection of incident beam, including and excluding nuclear interactions. This work is related with Medical Physics and Material Physics, like interaction of radiation with matter, particle transport phenomena, and the experimental methods in Nuclear Physics like simulation and computational by Monte Carlo method

Processamento de peças em materiais compósitos para o projeto BAJA SAE

The weight of a vehicle has always been considered an extreme important factor, because it interferes in the performance, steering, consume, environmental impact, wear of components, among the others. Because of the new demand, consume reduction aim and gases emission increased the necessity to manufacture lighter vehicles, guaranteeing the complying with the gas emission international law. Besides the legal demand, the low weight will certainly be essential for the competitiveness for the next generation of vehicles. It is with this thinking the composite materials have been introduced in the automobilist industry, because those materials show an excellent relation of strength/weight, providing a reduction of consume and the increase of load capacity. Those factors justify the increase of interest of industry and the necessity of optimization of those materials and of their process. For this research, the field of application will be the Baja SAE Project, a project that is fully developed by engineering students, where they build a prototype single seat, off-road category, for use on hilly slopes with obstacle. This research aims to study two key components of the prototype are made of composite materials, analyzing all the processing. In addition, there is the analysis of the viability of this production parts to a Baja SAE vehicle, in order to increase their performance and reduce their weight without reducing the safety and robustness of the prototype. It was possible to achieve weight reduction of the steering subsystem with manufacturing the flywheel hybrid composite (carbon/glass) and the replacement of SAE 1010 steel by hybrid composite (carbon/aramid) in CVT box. The importance of this study is to obtain a good project for the vehicle of technical and scientific manner, contributing to the know-how to the team and providing a basis for optimization for upcoming projects

Caracterização da liga do sistema binário Ti-15Mo para aplicações biomedicas

As they have excellent mechanical properties, corrosion resistance and biocompatibility, much research has been conducted with respect to biomedical applications of titanium alloys. This work aims to study the experimental system binary alloy Ti-15Mo, in the raw state of fusion and heat treatment after homogenization, solubilization and calcination (simulating conditions employed for nanotube growth) targeting biomedical applications. Samples were obtained by casting the components in an electric arc furnace with inert atmosphere of argon. After obtaining the alloy, it was heat treated at three different heat treatments, namely homogenizing, calcining and simulation solubilization. The phases present were analyzed by X-ray diffraction, optical microscopy and microhardness testing

Desvendando o sistema ABO: subsídios para o ensino de ciências e biologia

O conteúdo “Grupos sanguíneos” é abordado principalmente no ensino de biologia no Ensino Médio e está atrelado a diversas questões biológicas relevantes ao ensino básico. Além disso, sabe-se que esse tema é de cunho abstrato aos alunos, o que muitas vezes dificulta a apropriação do conteúdo pelo aluno. Nesse contexto, se torna relevante a elaboração de materiais que contribuam para um melhor processo de ensino e aprendizagem desse tema, além da incorporação da dimensão lúdica no universo escolar. Assim, a proposta do presente trabalho foi a elaboração de dois modelos didáticos de célula que facilitem a visualização da relação direta existente entre os genes responsáveis pela manifestação dos antígenos do sistema ABO, os genótipos dos diferentes indivíduos e as possibilidades de transfusão sanguínea existentes dentro de cada grupo sanguíneo. Além disso, foi construído um jogo didático de perguntas e respostas que envolvem os conhecimentos adquiridos durante a explanação teórica do professor com o intuito de fixação do conteúdo. O conteúdo fornecido neste trabalho foi baseado em livros didáticos, possibilitando aulas com conteúdo programático adequado e evitando erros conceituais

Efeitos dos parâmetros de usinagem no acabamento superficial de materiais cerâmicos a verde

Pós-graduação em Engenharia Mecânica - FEB

Analise de desgaste em materiais aplicados em discos de freio

Baja SAE competitions challenge engineering students to design and build offroad vehicles, preparing them for the competitive job market. This monograph aims to study a part of the braking of a Baja SAE vehicle system, the brake disc. Giving attention to the wear suffered by discs of two different materials, steel 1045 and stainless steel 304, helping the team Piratas do Vale Bardahl in the best selection between them. Braking tests were performed on a test bench. Both discs have suffered the same braking conditions. Brake pads material, brake line pressure, braking time, number of braking, were parameters which were repeated in the testing of different types of disk, in order to ensure a high power comparison between the obtained data. Before and after the disk tests were weighed and measured, to make a comparison. After the brake tests, the disks were subjected to hardness and surface roughness testing. With the data collected and observations made in the worn parts, the comparison between these two materials was made, obtaining a selection of the best material for the team. The tests showed that steel 1045 has more advantages, compared to stainless steel 304, when applied to brake discs, on the tested conditions

Evidência da presença do sistema AGR, expressão de toxinas e resistência aos antimicrobianos em estafilococos coagulase-negativa isolados de hemoculturas

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Disponibilidade de fósforo em solo tratado com resíduos urbanos e industriais sob sistema de plantio direto cultivado com soja

Pós-graduação em Agronomia (Agricultura) - FCA

Gestão de resíduos sólidos urbanos: contribuições socioambientais de duas cooperativas de catadores de materiais recicláveis na região do Médio Paranapanema

Pós-graduação em Biociências - FCLAS

Relação entre materiais dentários e o complexo dentino-pulpar

Despite the strong valorization of the esthetics and its relationship with restorative materials, the biological principles of any clinical procedure are extremely important to maintain the vitality of the dentin-pulp complex. Dentin and pulp tissue are susceptible to different kinds of irritants such as toxins from microorganisms, traumatic procedures of cavity preparation, as well as toxic components released by restorative materials applied in non recommended clinical situations. Initially, the pulp responds to irritation by starting an inflammatory reaction which involves outward movement of dentinal fluid and intratubular deposition of immunoglobulins, upregulation of odontoblast activities, presence of immune cells and their cytokines as well as local expression of neuropeptides and chemokines. After these initial events, the inflammation process can be resolved associated or not to sclerotic dentin formation and reactionary dentin deposition. If high intensity offensive stimuli are applied to the dentin-pulp complex, death of odontoblasts takes place and consequently pulp ageing or even partial necrosis of this tissue may occurs. Thereby, clinicians need to be aware about the physiological and pathological features of the dentin-pulp complex as well as the possible biological consequences of different clinical procedures. In this way, the dentists should be able to carry out minimally aggressive operative techniques and to select the more appropriate restorative materials for each specific clinical situation in order to obtain excellent clinical results associated to the maintenance of pulp vitality.

Reabilitação estética do sorriso por meio do sistema cerâmico dissilicato de lítio: relato de caso

The reestablishment of a harmonious smile through dental ceramics, when properly conducted and with specific indications, can achieve extremely predictable results. For aesthetic and functional rehabilitation, many ceramic materials can be used such as zirconia, leucite, alumina, feldspar, and lithium disilicate. Among these materials the lithium disilicate stands out due to the following characteristics: its resistance to wear, to chemical attack, high temperatures and oxidation; low electrical conductivity; near zero thermal expansion; good optical properties and biocompatibility with periodontal; excellent esthetics; color stability and reinforcement of tooth structure. The indications for the use of lithium disilicate are not limited to multiple facets of teeth in cases where there was no favorable response to tooth whitening, and also comprehend teeth with multiple restorations, diastema closure, shape alteration, and dental contouring, replacement of missing or fractured teeth, among others. The versatility of lithium disilicate ceramics allows its utilization in several clinical situations. The concomitant use of lithium disilicate for veneers and over metal has satisfactory aesthetic results, as reported in the present studying cases that require both aesthetics and resistance.